Asbestos in soil and made ground: a guide to understanding...

The term ‘asbestos’ relates to several fibrous minerals regulated under UK law that areknown to cause serious health effects (including mesothelioma and lung cancer) wheninhaled. Asbestos containing materials (ACMs) were widely used in construction, and thisguide identifies several key areas of uncertainty in current understanding, withrecommendations future research and policymaking in order to address them.

However, due to these uncertainties, the characterisation and assessment of potentialrisks is not straightforward, and similar difficulties are being encountered in otherdeveloped countries. This guide recommends a ‘lines of evidence’ approach wherebymore than one method is used to estimate the airborne fibre concentrations likely to begenerated from soils at the site.

C733

C73

3Asbestos

insoiland

made

ground:aguide

tounderstanding

andm

anagingrisks

CIRIA9 780860 177371

Asbestos in soil and made ground:a guide to understanding

and managing risks

Licensed copy:Arup, 15/08/2016, Uncontrolled Copy, © CIRIA

Errata Readers are advised that Box 13.3 on page 110 has been revised to include a new graph from Addison et al (1988).

The correct pages are included on page 2 here.

We apologise for any inconvenience this may have caused.

Publication C733

Asbestos in soil and made ground: a guide to understanding and managing risks


CIRIA, C733110

�� measured soil concentrations of asbestos fibres (per cent) are available

�� the likely soil dust in air concentrations (mg/m3) can be estimated or measured.

Box 13.3 Example calculation based on predictive modelling (after Addison et al, 1988)

The Addison et al (1988) data was gathered under controlled laboratory conditions, which reduces the variation inherent in site measurements (ie dilution rates, weather, wind speeds and directions). The predictive modelling approach can also be very flexible. By using appropriate assumptions, it can take account of:

�� different types of activity

�� different climates and soil moistures

�� different asbestos type(s) (eg bound ACM, friable ACM or free fibres)

�� future changes in the condition of ACM due to weathering, degradation etc

Predictive modelling approaches are the only feasible way to estimate this expected future release from friable ACMs that will continue to weather in soils or be physically degraded by site activities.

However, the Addison data involved mixtures of dried and milled soils and pure asbestos fibres (not ACM) under disturbance conditions more extreme than are likely to be encountered at most sites and “moderately aggressive in comparison to other methods” (page 19 of Addison et al, 1988). The resulting predictions are therefore likely to be cautious, and careful consideration should be given to all assumptions and inputs if an overly conservative estimate of airborne fibre concentration is to be avoided in ‘real world’ conditions. The relevance of predictions made using such predictive modelling should be clearly established on a site-specific basis by the risk assessor, including a consideration of differences in soil type, form of ACM etc.

An example of how predictive modelling can be used to estimate airborne concentrations is presented in Box 13.3. However, this example relies entirely on the data from a single study.

13.4.1 Appropriate soil concentrationThere is likely to be considerable variation within the reported asbestos in soil concentrations at any given site. The implications of such variation should be carefully considered before selecting the

The results of Addison et al (1988) in Figure 13.1 were used to estimate the likely asbestos in air concentration based on measurements of concentrations of asbestos in representative soil samples taken from a single domestic garden. The asbestos concentration in soil was estimated to be 0.1 per cent amosite. The soil was clay.

The predicted normalised fibre concentration from the graph was 0.1 f/ml per mg/m3. The concentration of soil dust during gardening activities in dry and dusty conditions was estimated at about 100 μg/m3 (ie 0.1 mg/m3), based on ambient urban dust levels and ART modelling of shovelling dry powders. Therefore, an airborne fibre concentration during such activities in dry and dusty conditions was estimated to be 0.01 f/ml (Ci), and assumed to be insignificant at other times. Residents were assumed to conduct activities in gardens under dry and dust conditions for an average of 90 hours per year (Fi.Ti).

So [annual] exposure would have to be:

Ei = Ci × Fi × Ti

Ei = 0.01 f/ml × 90 hours/year = 0.9 f/ml.hours/year

For a young child this would amount to say Yi = 6 years so cumulative exposure would be:

CEi = Ei × Yi

CEi = 0.9 f/ml.hours/year × 6 years = 5.4 fibre/ml.hours = 5.4/2000 fibre/ml.years= 0.0027 fibre/ml.years

Monitoring for asbestos in air provided data to support the assumption that concentrations would be insignificant under Part 2A in wet or damp weather/soil conditions.

Figure 13.1 Amosite in clay


Who we areEstablished in 1960, CIRIA is a highly regarded, industry-responsive, not for profit research and information association, which encompasses the construction and built environment industries.

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CIRIA C733 London, 2014

Asbestos in soil and made ground: a guide to understanding and

managing risksP Nathanail Land Quality Management Ltd

and University of NottinghamA Jones Institute of Occupational Medicine

R Ogden Land Quality Management LtdA Robertson Institute of Occupational Medicine

Griffin Court, 15 Long Lane, London, EC1A 9PNTel: 020 7549 3300 Fax: 020 7549 3349Email: [email protected] Website: www.ciria.org


CIRIA, C733ii

Asbestos in soil and made ground: a guide to understanding and managing risks

Nathanail, C P, Jones, A, Ogden, R, Robertson, A

CIRIA

C733 RP961 © CIRIA 2014 ISBN: 978-0-86017-737-1

British Library Cataloguing in Publication Data

A catalogue record is available for this book from the British Library

Keywords

Contaminated land, ground engineering, sustainability

Reader interest

This guide provides coherent information for clients, landowners or developers and their advisors, regulators and other stakeholders on the safe investigation, assessment and remediation of soil and made ground containing, or suspected of containing, free asbestos fibres or asbestos-containing materials. It contains a digest of contemporary information and guidance with the aim of raising current good practice.

Classification

Availability Unrestricted

Content Advice/guidance

Status Committee-guided

Users Clients, landowners, developers, house builders, local authorities, other regulators, consultants and contractors

Published by CIRIA, Griffin Court, 15 Long Lane, London EC1A 9PN, UK

This publication is designed to provide accurate and authoritative information on the subject matter covered. It is sold and/or distributed with the understanding that neither the authors nor the publisher is thereby engaged in rendering a specific legal or any other professional service. While every effort has been made to ensure the accuracy and completeness of the publication, no warranty or fitness is provided or implied, and the authors and publisher shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from its use.

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, without the written permission of the copyright holder, application for which should be addressed to the publisher. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature.

If you would like to reproduce any of the figures, text or technical information from this or any other CIRIA publication for use in other documents or publications, please contact the Publishing Department for more details on copyright terms and charges at: [email protected] Tel: 020 7549 3300.

Front cover: Amiandos mine, Troodos, Cyprus. From the archives of Jules Chr. Parisinos 1924–2009 (courtesy Marina Parisinou)


Asbestos in soil and made ground iii

Summary

The term ‘asbestos’ relates to several fibrous minerals regulated under UK law that are known to cause serious health effects (including mesothelioma and lung cancer) when inhaled. Asbestos containing materials (ACMs) were widely used in construction, and it is difficult (and sometimes not possible) to ensure that all asbestos is removed before demolition. Building rubble is liable to contain ACM, and may contain free fibres. ACM fragments in rubble or soil can be difficult to detect by the naked eye whereas free fibres in rubble or soil are generally not visible.

The Control of Asbestos Regulations (CAR) 2012 requires actions to ensure the protection of workers and general public from asbestos exposures resulting from work activities. However, current case law suggests that landowners and developers could find themselves liable for claims under the Compensation Act 2006 in the future, even if CAR and planning requirements have been satisfied. In order to avoid such claims, adequate attention needs to be paid to potential risks from asbestos-containing soils (ACSs) during all redevelopment.

The concentration of airborne fibres released is influenced by many factors including asbestos type, ACM type and condition/state, depth, distribution and concentration in soil, soil type, and soil moisture content. There is limited data on the release of airborne fibres from soils in real world environments, but soil moisture content has a particularly significant impact. Increasing amounts of fibres are likely to be released over time as ACMs deteriorate. Friable ACMs (eg lagging and asbestos insulating board) release fibres much more easily, and are likely to deteriorate faster, than firmly bound materials (eg asbestos cement), which may take a very long time to degrade, if undisturbed.

In principle, the general tiered approach to the assessment and management of potential risks posed by ACSs is the same as that for any other contaminant. However, the unique nature of asbestos means that different methods of analysis, exposure estimation and risk estimation are required. Importantly, soil and air analysis methods may need to be more detailed than those currently commonly used to demonstrate compliance with CAR.

This guide identifies several key areas of uncertainty in current understanding, and recommendations are made for future research and policy making in order to address them. However, due to these uncertainties, the characterisation and assessment of potential risks is not straightforward, with similar difficulties also being encountered in other developed countries. This guide recommends a ‘lines of evidence’ approach whereby more than one method is used to estimate the airborne fibre concentrations likely to be generated from soils at the site. Except at low-risk sites, measuring soil concentrations alone is unlikely to be sufficient. Based on the estimated airborne concentrations, cumulative exposures can be estimated for exposure scenarios relevant to the site under assessment, and existing exposure-risk models are available to indicate the level of risk such exposures may pose. Asbestos in soil thresholds cited for other purposes (such as the hazardous waste threshold and the detection limit mentioned in ICRCL, 1990) should not be used for the assessment of risk.

The requirements of CAR 2012 and other relevant legislation (eg relating to waste and the carriage of dangerous goods) need to be complied with throughout. Due to high public awareness of the dangers of asbestos, effective risk communication will also be required at many affected sites.


CIRIA, C733iv

Acknowledgments

The project was carried out under contract to CIRIA by a consortium led byLand Quality Management Ltd and Institute of Occupational Medicine. This project is funded by Campbell Reith Hill LLP, ICE (Research and Development Enabling Fund), National Grid, Crossrail, Chemtest, Hydrock, Peter Bretts Associates LL, SNIFFER, Akzonobel, Lucion, RSK, Taylor Wimpey, Redhills and CIRIA Core members.

Authors

Paul Nathanail MA(Cantab) MSc DIC PhD EuroGeol CGeol SILC

Paul Nathanail is professor of engineering geology at the University of Nottingham and managing director of Land Quality Management Ltd. He runs the Nottingham e-learning Masters course in contaminated land management. He is a chartered geologist and Specialist in Land Condition (SiLC). The pioneering work of LQM in developing generic assessment criteria for substances for which no SGV was available revolutionised generic quantitative risk assessment under the planning regime. The LQM/CIEH Dose Response Roadmaps have since been developed to assist local authorities in evaluating whether or not sites pose a significant possibility of significant harm.

Alan Jones BSc (Hons) MPhil PhD

Alan Jones is a senior consultant at IOM. He has been involved in health and safety research at IOM for over 30 years, and has assisted or led many studies relating to asbestos. He has worked with a wide variety of clients, including UK Government departments, HSE, Defra, local authorities, US NIOSH, UK and international companies. Alan is currently associated with expert witness work (concerning asbestos litigation) and provides advice on asbestos in soils and also incidents involving exposures to asbestos. Alan has written over 100 published papers and reports.

Richard Ogden BSc (Hons) PhD

Richard Ogden is a senior environmental scientist at Land Quality Management Ltd, and has over 10 years’ experience in the field of contaminated land assessment and remediation. He gained a degree in biochemistry and marine biology and went on to study the genetic and molecular bottlenecks in the biological remediation of BTEX, PAHs and PCBs at the University of Wales, Bangor. Richard is a member of the team responsible for the development of the LQM/CIEH Dose Response Roadmaps and both first and second editions of the LQM/CIEH GAC.

Alastair Robertson BSc (Hons) PhD

Alastair Robertson has recently retired from his post as a senior consultant at IOM. He was involved in IOM’s research and consultancy relating to health at work and in the general environment for almost 40 years. He was a member of IOM’s Board of Management for 18 years and was in charge of IOM’s consultancy and services work for 10 years. His experience in asbestos in soils extends over 25 years, working more recently on major, ground-breaking projects for both public and private sector clients.

Project steering groupRachael Adams Ministry of Defence (MoD)

Bill Baker Independent consultant (representing Chartered Institute of Environmental Health

Chris Barrett Arup


Asbestos in soil and made ground v

Jane Beckmann Health and Safety Executive (HSE)

Adam Binney Network Rail

Seamus Lefroy Brooks LBH Wembley Geotechnical and Environmental (also representing Association of Geotechnical and Geoenvironmental Specialists)

Stuart Chandler Peter Brett Associates

James Clay Campbell Reith Hill LLP

Hazel Davidson DETS

Claire Dickinson AECOM (chair)

Frank Evans National Grid

Steve Forster IEG Technologies UK Limited (also representing EIC-CL:AIRE Joint Industry Working Group on Asbestos in Soil, Made Ground and Construction & Demolition Materials)

Matt Hussey OAMP (formerly Tyser)

Paul Gribble ALcontrol Laboratories

Matt Griggs Redhills

Simon Hay Arcadis

Ian Heasman Taylor Wimpey (also representing Soil and Groundwater Technology Association

Phil Hellier Chemtest

Ursula Lawrence Crossrail

Ian Martin Environment Agency

David Robinson Transport for London

Phil Rozier Lucion Environmental Ltd

Carl Slater Waterman

Chris Vincett Hydrock

Paula Whittell Independent (formerly Berrymans Lace Mawer)

George Wilkinson Akzonobel

Rebecca Williams SNIFFER

Project managersChris Chiverrell Project director

Joanne Kwan Project manager

Other contributorsThe project team would also like to thank many people and organisations who have provided advice and information during the project. This includes members of the EIC-CL:AIRE Joint Industry Working Group on Asbestos in Soil, Made Ground and Construction & Demolition Materials, the Soil and Groundwater Technology Association (SAGTA), VSD Avenue (a consortium comprising VolkerStevin Ltd, Sita Remediation NV and DEME Environmental Contractors BV), Charles Feeny, Barrister, St Johns Buildings, Liverpool, and contributing editor, Pro-Vide-law.co.uk

This guide represents the views of the authors who are grateful for all the comments and suggestions received from the people and organisations listed. However, the authors acknowledge that the information presented in this guide does not reflect all the views expressed.


CIRIA, C733vi

Contents

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

Abbreviations and acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

1.1 Aim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Structure of the guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.4 What are ‘soil’ and ‘made ground’? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.5 Legal context . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.6 Units of measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.7 Function and Limitations of the guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Client requirements for assessment and management of risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

2.1 Legislation and policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2 Existing UK and other national guidance on asbestos in soil and made ground . . . . . . . . . . . . . . . . 72.3 Health effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.4 Human exposures to asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.5 Release of airborne fibres from asbestos-containing soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.6 Complying with the Control of Asbestos Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.7 Appointment of specialists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.8 Preliminary risk assessment (PRA) and developing the conceptual site model (CSM) . . . . . . . . . . . 92.9 Soil sampling and analysis of asbestos in soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112.10 Air monitoring and analysis of asbestos in air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112.11 Exposure estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122.12 Risk estimation and evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122.13 Remediation and management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142.14 Risk communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142.15 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Part 1 Understanding the risks of asbestos in soil and made ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3 Legislation relating to asbestos in soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183.1.1 Control of Asbestos Regulations 2012 (CAR 2012) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .203.1.2 Construction (Design and Management) Regulations 2007 (CDM). . . . . . . . . . . . . . . . .233.1.3 The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013 (RIDDOR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

3.2 The common law of negligence and nuisance (including the Compensation Act 2006) . . . . . . . . .243.2.1 Sienkiewicz v Greif (UK) Limited and Knowsley Metropolitan Borough Council v Willmore, [2011, UKSC 10] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263.2.2 Williams v Birmingham University [2011] (EWCA Civ 1242). . . . . . . . . . . . . . . . . . . . . . .26

3.3 Planning, Development Control and the Environmental Protection Act 1990 . . . . . . . . . . . . . . . . .273.3.1 The planning system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273.3.2 Part 2A of the Environmental Protection Act 1990. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

3.4 Environmental Damage (Prevention and Remediation) Regulations 2009 . . . . . . . . . . . . . . . . . . .293.4.1 Summary of regulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303.4.2 Applicability to asbestos-containing soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31


Asbestos in soil and made ground vii

3.5 Waste legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313.6 Waste classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333.7 Registration, Evaluation, Authorisation & restriction of CHemicals Regulations 2008 (REACH). . . . . .333.8 Packaging and Labelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

4 Asbestos types, uses and products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.1 Types of asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .374.2 Asbestos uses and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .384.3 Asbestos-containing demolition materials and construction waste . . . . . . . . . . . . . . . . . . . . . . . . .38

5 Asbestos and health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.1 Non-malignant pleural disease. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .395.2 Asbestosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .395.3 Asbestos-related cancers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

5.3.1 Lung cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .405.3.2 Mesothelioma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .405.3.3 Indications of disease caused by environmental exposures . . . . . . . . . . . . . . . . . . . . . .41

5.4 Fibre potency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415.5 Fibre size. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425.6 Clearance mechanisms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425.7 What is an appropriate basis for assessing asbestos-containing soils? . . . . . . . . . . . . . . . . . . . . .42

5.7.1 Threshold or non-threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435.7.2 Carcinogenic mode of action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435.7.3 Metric of exposure and thresholds for environmental exposures . . . . . . . . . . . . . . . . . .44

6 Human exposures to asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

6.1 Occupational exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .466.2 Para-occupational exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .466.3 Environmental exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

6.3.1 Background concentrations in outdoor air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .476.3.2 Background concentrations in indoor air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .486.3.3 Background concentration of asbestos in soil and made ground . . . . . . . . . . . . . . . . . .48

7 Existing UK and other national guidance on asbestos in soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

7.1 ‘Asbestos on contaminated sites’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .507.2 AGS interim guidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .517.3 Applicability of other guidance to the UK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

8 Complying with CAR: risk assessments, licensing and training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

8.1 CAR Risk assessments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .548.1.1 During site reconnaissance visits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .558.1.2 During site investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .558.1.3 During remediation, redevelopment and construction activities. . . . . . . . . . . . . . . . . . .558.1.4 Respiratory protective equipment (RPE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

8.2 Licensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .568.3 Training requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

8.3.1 Unique requirements for site reconnaissance, site investigation and remediation workers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .588.3.2 Health and safety training required under CAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

8.3.2.1 Asbestos awareness training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .598.3.2.2 Training requirements when ACMs will be disturbed . . . . . . . . . . . . . . . . . . . . .59

8.3.3 Proficiency training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .608.3.4 Training vs. competence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

9 Releaseofairbornefibresfromasbestos-containingsoils(ACSs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

9.1 Release of wind-blown fibres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .639.2 Release of fibres by physical disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .649.3 Consideration of depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66


CIRIA, C733viii

9.4 Consideration of land use and activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .669.5 Consideration of asbestos type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .679.6 Consideration of different types of ACM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

9.6.2 Weathering and degradation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .709.7 Consideration of soil characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

9.7.1 Influence of soil type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .709.7.2 Influence of soil moisture content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Part 2 Managing the risks of asbestos in soil and made ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

10 Preliminary risk assessment and developing the conceptual site model . . . . . . . . . . . . . . . . . . . . . . . . . .74

10.1 General principles of conceptual site modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7410.2 Potential sources: scope and considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

10.2.1 Manufacturing sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7510.2.2 Waste management sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7510.2.3 Demolition sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7610.2.4 Sites affected by imported materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7610.2.5 Mode of deposition and proposed earthworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

10.3 Potential exposure pathways: scope and considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7710.3.1 Exposure via outdoor inhalation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7710.3.2 Exposure via indoor inhalation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7810.3.3 Waterborne fibres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

10.4 Potential receptors: scope and considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7910.4.1 The receptors to be considered for asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7910.4.2 Receptors not relevant for asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

10.5 Preliminary risk assessment (PRA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7910.5.1 Desk study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8010.5.2 Site reconnaissance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

11 Soil sampling and analysis of asbestos in soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8411.1.1 What type of data is required? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84

11.2 Soil sampling strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8811.2.1 Access methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8911.2.2 Soil sampling protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91

11.3 Analysis of asbestos in soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9411.3.1 Soil analysis using optical microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9411.3.2 Other methods of quantifying asbestos. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9611.3.3 Measurement of ‘fibre release potential’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9611.3.4 Analysis of indoor surface dust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9711.3.5 Accreditation of testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

12 Air monitoring and analysis of asbestos in the air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

12.1 Sampling and analytical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10012.1.1 Accreditation of air testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10212.1.2 Analytical errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102

12.2 Air monitoring strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10212.2.1 Ambient air monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10312.2.2 Indoor air monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10412.2.3 Activity based sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

13 Exposure estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

13.1 Principles of exposure assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10613.1.1 Local climate and other considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

13.2 Calculating exposures and cumulative exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10713.3 Use of outdoor air monitoring data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10813.4 Use of published soil-to-air relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109


Asbestos in soil and made ground ix

13.4.1 Appropriate soil concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11013.4.2 Deriving soil-dust in air concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11113.4.3 Friability of different ACMs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111

13.5 Use of ‘potential fibre release’ tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11113.6 Atmospheric dispersion and dilution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11213.7 Use of indoor exposure information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11213.8 Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

14 Risk estimation and evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

14.1 Qualitative risk evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11514.2 Generic quantitative risk assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11514.3 Detailed quantitative risk assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

14.3.1 The basis for risk modelling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11614.3.2 Mesothelioma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11714.3.3 Lung cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11914.3.4 Overall excess lifetime risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11914.3.5 Data requirements for predicting risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

14.4 Potency differences of asbestos minerals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12014.4.1 Mesothelioma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12014.4.2 Lung cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

14.5 Uncertainty in the models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12114.5.1 Exposures in epidemiological studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12214.5.2 Applicability to non-occupational exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12214.5.3 Extended exposure duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

14.6 Risk evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12414.6.1 Unacceptable levels with respect to Part 2A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12514.6.2 Acceptable levels with respect to redevelopment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

15 Remediation and risk management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

15.1 Remediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12815.2 Leave in situ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

15.2.1 Cover systems and capping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13015.3 On-site reuse or treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

15.3.1 On-site reuse of asbestos-containing soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13115.3.2 On-site disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13115.3.3 On-site treatment of asbestos-containing soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13215.3.4 Hand-picking of visible asbestos from soil or rubble . . . . . . . . . . . . . . . . . . . . . . . . . . 13215.3.5 Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13315.3.6 Solidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13415.3.7 Off-site disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13415.3.8 Off-site treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

15.4 Future and emerging technologies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13415.4.1 Soil washing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13515.4.2 In situ vitrification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13515.4.3 Plasma arc technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13515.4.4 Thermo-chemical conversion technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13515.4.5 Acid destruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13515.4.6 Microwave destruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

15.5 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13615.6 Importing soils and aggregates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13715.7 Documenting the presence of asbestos-containing soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13715.8 Additional liability transfer mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

16 Risk communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

16.1 Potential blight, commercial liability and reputational damage. . . . . . . . . . . . . . . . . . . . . . . . . . . .14116.2 Good practice in communicating the risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141


CIRIA, C733x

17 Appointment of consultants, contractors and specialists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

17.1 Issues to consider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14317.1.1 Insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

17.2 Competencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14417.2.1 Contaminated land competencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14417.2.2 Asbestos-related competencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

18 Conclusions and recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

18.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14818.1.1 Historical asbestos legacy for redevelopment sites in the UK (Chapters 4 and 11) . 14818.1.2 Health risks from asbestos (Chapter 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14818.1.3 Regulation of work with asbestos (Chapter 8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14818.1.4 Preliminary risk assessment and developing the conceptual site model (Chapter 10) . . .14918.1.5 Sampling and analysis of soil samples (Chapter 12) . . . . . . . . . . . . . . . . . . . . . . . . . . .14918.1.6 Air monitoring and analysis of asbestos in air (Chapter 13). . . . . . . . . . . . . . . . . . . . . 15018.1.7 Exposure estimation (Chapter 14) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15018.1.8 Risk estimation and evaluation (Chapter 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15118.1.9 Remediation and management (Chapter 16) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15118.1.10 Risk communication (Chapter 16) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152

18.2 Recommendations for further developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15218.2.1 Hazard classification of ACSs and when CAR 2012 will apply to such soils . . . . . . . . .15218.2.2 Guidance on LW and NLW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15218.2.3 Adapting laboratory analytical reports to suit the purpose of quantitative site risk assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15318.2.4 Fibre releasability database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15318.2.5 Commercial fibre release testing for site-specific soil . . . . . . . . . . . . . . . . . . . . . . . . . 15318.2.6 Current background concentrations of asbestos in air and soils . . . . . . . . . . . . . . . . 15318.2.7 Using Dutch research on negligible risk levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15318.2.8 Software implementation of models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15318.2.9 Appropriate record keeping on the presence of asbestos in soils. . . . . . . . . . . . . . . . 15318.2.10 Better understanding of the risk from low levels of non-occupational exposure . . . . 15418.2.11 Comparative studies to define cost effective methods and requirements for environmental monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

Statutes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

Useful websites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

A1 ACMsinbuildingslistedinorderofeaseoffibrerelease(afterAppendix2ofHSE,2010) . . . . . . . . . 167

A2 Case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

A3 Review of Australian and New Zealand policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

A3.1 Guidelines on the assessment, remediation and management of asbestos-contaminated sites in Western Australia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

A4 Review of Netherlands policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

A4.1 Dutch policy on asbestos in air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187A4.2 Derivation of a generic assessment criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188A4.3 Tiered approach to asbestos in soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

A5 Review of US EPA policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

Boxes

Box 3.1 Sienkiewicz v Greif (UK) Limited and Knowsley Metropolitan Borough Council v Willmore, [2011, UKSC 10] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Box 3.2 Williams v Birmingham University [2011] (EWCA Civ 1242) (cf BAILII, 2011) . . . . . . . . . . . .27Box 3.3 National planning policy guidance in England, Wales and Scotland . . . . . . . . . . . . . . . . . . . .28


Asbestos in soil and made ground xi

Box 5.1 Possible modes of action for asbestos proposed by ATSDR (2001 and 2010) . . . . . . . . . . .44Box 5.2 Definition of fibre equivalents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44Box 9.1 Vermiculite mining and natural contamination in Libby, Montana . . . . . . . . . . . . . . . . . . . . .66Box 11.1 Encountering ACM during a site investigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92Box 11.2 The main steps commonly used in the quantification of asbestos in soil . . . . . . . . . . . . . . .95Box 11.3 Certificates of analysis for quantification of asbestos in soil . . . . . . . . . . . . . . . . . . . . . . . . .95Box 11.4 Outline of various ‘fibre release potential’ tests from around the world. . . . . . . . . . . . . . . . .97Box 12.1 Outdoor air monitoring alongside various rights of way in Cambridgeshire . . . . . . . . . . . . .103Box 13.1 Rights of way and byways in Cambridgeshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109Box 13.2 Example calculation based on air monitoring data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109Box 13.3 Example calculation based on predictive modelling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110Box 13.4 Hypothetical example of the use of ‘potential fibre release test data . . . . . . . . . . . . . . . . 112Box 14.1 Hypothetical worked example – risk from environmental exposure . . . . . . . . . . . . . . . . . . 120Box 14.2 Mesothelioma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121Box 14.3 Lung cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121Box 15.1 Receptor modification strategies applicable to asbestos-contaminated soils . . . . . . . . . 129Box 15.2 Outline of the application of solidification/stabilisation to asbestos-containing soils . . . 134Box 15.3 Application of ‘lines of evidence’ approach to asbestos-containing soils . . . . . . . . . . . . . 136Box 16.1 Risk perceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141Box 16.2 Risk communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141Box 16.3 Communication strategy, Wolverhampton City Council, UK. . . . . . . . . . . . . . . . . . . . . . . . . .142Box A4.5 Outline of the tiered assessment process adopted in the Netherlands. . . . . . . . . . . . . . . 189

Case studies

Case study A2.1 Part 2A inspection of a housing estate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174Case study A2.2 Former large industrial site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176Case study A2.3 Woolston Riverside (former Vosper Thornycroft Shipyard). . . . . . . . . . . . . . . . . . . . . . . . . . .177Case study A2.4 Housing development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178Case study A2.5 Former industrial site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179Case study A2.6 Former brickworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180CAse study A2.7 Former landfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181Case study A2.8 Asbestos on rights of way in South Cambridgeshire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

Figures

Figure 2.1 Flowchart of a preliminary risk assessment (PRA) process . . . . . . . . . . . . . . . . . . . . . . . . . . .10Figure 2.2 Flowchart of a risk estimation and risk evaluation process. . . . . . . . . . . . . . . . . . . . . . . . . . .13Figure 3.1 Vehicle placard and warning sign for asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35Figure 3.2 UN compliant packaging for asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35Figure 5.1 Asbestos imports compared to actual and predicted mesothelioma deaths . . . . . . . . . . . .41Figure 8.1 Sample containing asbestos (courtesy DETS Laboratories) . . . . . . . . . . . . . . . . . . . . . . . . . .59Figure 8.2 Examples of asbestos and ACMs in soils and made ground . . . . . . . . . . . . . . . . . . . . . . . . . .60Figure 9.1 Average airborne asbestos concentrations from simulated and field measurements . . . . .66Figure 9.2 Showing the dust raised during dry weather by lorry movements on a track partly

surfaces with crushed asbestos cement (a), and a close-up of the asbestos cement fragments at the track surface (b). For scale, the sample vial is roughly 10 cm in height . . .67

Figure 9.3 Indicating the effect of asbestos type on airborne fibre . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68Figure 9.4 ‘Respirable’ asbestos fibres fraction for amphibole and chrysotile asbestos according

to bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69Figure 9.5 Relative release of PCM fibres in dustiness tester for different types of asbestos-

containing materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69Figure 9.7 Indicating the potential reductions in airborne fibre count with increasing soil moisture. . . 71Figure 10.1 Examples of ACMs encountered at the surface during a site walkover . . . . . . . . . . . . . . . . .82Figure 10.2 Potential sources of asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83Figure 11.1 Suspected ACM fragment collected from soil. Later laboratory analysis confirmed the

presence of asbestos within this material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93


CIRIA, C733xii

Figure 15.1 Construction of a cap over a deep pocket of asbestos-containing soil . . . . . . . . . . . . . . . 130Figure 15.2 Damping down and use atomised water sprays to inhibit the release of airborne

asbestos fibres during a skip being loaded (a), and soil stockpiling (b) . . . . . . . . . . . . . . . .131Figure 15.3 Handpicking of asbestos and ACMs from stockpiled soil. . . . . . . . . . . . . . . . . . . . . . . . . . . 133Figure A4.1 Dutch tiered site specific human health risk assessment framework for asbestos-

containing soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190Figure A5.1 Flow diagram for investigating asbestos-contaminated superfund sites adopted by

the US EPA (2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

Tables

Table 1.1 Conversion between standard units used for soil concentrations (milligrams per kilogram soil (mg/kg) and percentage asbestos by weight (%)) and air concentrations (fibres per millilitre (f/ml) and fibres per cubic metre (- f/m3)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Table 3.1 Main UK law relevant to aspects of asbestos-containing soils . . . . . . . . . . . . . . . . . . . . . . . .19Table 3.2 Commentary on selected parts of Control of Asbestos Regulations 2012 . . . . . . . . . . . . . .21Table 6.1 Background asbestos concentrations reported in indoor and outdoor air. . . . . . . . . . . . . . .48Table 8.1 Suitable types of RPE for most short duration non-licensed asbestos work . . . . . . . . . . . . .56Table 8.2 Existing asbestos-related BOHS proficiency training modules . . . . . . . . . . . . . . . . . . . . . . . .61Table 9.1 Factors affecting the release of airborne fibres from asbestos-containing soils. . . . . . . . . .63Table 10.1 Industries as particularly significant sources of asbestos in soils . . . . . . . . . . . . . . . . . . . . .75Table 11.1 Comparing the potential advantages and disadvantages of different lines of evidence for

use in estimating potential human exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86Table 11.2 Factors to be considered in designing an investigation of asbestos-containing soils. . . . . .88Table 11.3 Some common access methods and considerations for use with asbestos-containing soils . . . .90Table 11.4 BDA site designation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91Table 14.1 Risk summary statements for mesothelioma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Table 14.2 Age adjustment factors for mesothelioma risk dependant on the age at which

exposure starts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Table 14.3 Risk summary statements for asbestos-related lung cancer . . . . . . . . . . . . . . . . . . . . . . . 119Table 14.4 Categories of land with respect to ‘significant possibility of significant harm’ to human

health (England and Wales only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125Table 17.1 The range of asbestos-related competencies potentially needed by consultants, and

consortia, investigating and assessing the risks posed by ACSs at contaminated sites for three illustrative scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

Table A3.1 The three types of asbestos defined in Western Australia. . . . . . . . . . . . . . . . . . . . . . . . . . 185Table A3.2 Showing generic soil asbestos criteria adopted in Western Australia . . . . . . . . . . . . . . . . 185Table A4.1 Comparison of the existing maximum permissible risk (MPR) and negligible risk (NR)

levels for asbestos in air with revised levels proposed by the Health Council of the Netherlands. All values are expressed in fibres/m3 as measured using transmission electron microscopy (TEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187


Asbestos in soil and made ground xiii

Glossary

Asbestiform Having the form or structure of asbestos. It implies a particular kind of fibrosity in which fibres have high tensile strength and flexibility (from Merriam-Webster online dictionary).

Asbestos cement “Material which is predominantly a mixture of cement and chrysotile and which when in a dry state absorbs less than 30% water by weight“ (CAR 2012).

Asbestos coating A surface coating which contains asbestos for fire protection, heat insulation or sound insulation but does not include textured decorative coatings (CAR 2012).

Asbestos insulating “Any flat sheet, tile or building board consisting of a mixture of asbestos and other board material except:

(a) asbestos cement

(b) any article of bitumen, plastic, resin or rubber which contains asbestos, and the thermal or acoustic properties of the article are incidental to its main purpose” (CAR 2012).

Asbestos insulation “Any material containing asbestos which is used for thermal, acoustic or other insulation purposes (including fire protection) except:

(a) asbestos cement, asbestos coating or asbestos insulating board

(b) any article of bitumen, plastic, resin or rubber which contains asbestos and the thermal and acoustic properties of that article are incidental to its main purpose” (CAR 2012).

Asbestos-containing Any material that contains asbestos above trace quantities. material(ACM)

Aspect ratio The ratio of the length of a fibre to its diameter.

Bonded ACM Material where the asbestos fibres are contained in a matrix, such as resins or cement (locked into a matrix, eg asbestos cement, vinyl tiles). If in reasonable condition, the release of respirable fibres from bonded ACMs in soils is likely to be low. HSE (2010) (Appendix 2) gives a table of ACMs in buildings, listed in order of ease of fibre release.

Brownfieldsite A site that has been affected by former uses of the site or surrounding land, is derelict or underused, is mainly in fully or partly developed urban areas, requires intervention to bring it back to beneficial use, and may have real or perceived contamination problems.

Cement-bonded Collective term for materials containing asbestos in a cement matrix, including high asbestos density (eg asbestos cement) and low density (eg asbestos insulating board)

materials.

Cohort A designated group of people followed or traced over a period of time.

Conceptual site A diagrammatic and tabular representation of the characteristics of the site model shows the possible relationships between contaminants, pathways and receptors as

well as relevant uncertainties.

Control limit “A concentration of asbestos fibres in the atmosphere when measured in accordance with the 1997 WHO recommended method, or by a method giving equivalent results to that method approved by the HSE of 0.1 f/ml of air (100,000 fibres/m3) averaged over a continuous period of 4 hours” (CAR 2012).


CIRIA, C733xiv

Environmental Exposures that result from background concentrations of asbestos in air (ie (exposure) exposures other than occupational or para-occupational exposures).

Exposure scenario Detailed description of all events likely to result in human exposure to airborne asbestos fibres from soil, and the factors and considerations that influence these potential exposures.

Fibre A particle that is 5 µm or longer, with a length-to-width aspect ratio of 3:1 or longer.

Fibril A fine filament or fibre approximately 150 Angstroms in diameter (Naumann and Dresher, 1966).

Friable ACM These release asbestos fibres easily. They ”may be crumbled or pulverised or reduced to powder by hand pressure when dry, eg pipe insulation, sprayed insulation, millboard. Disturbance of these materials can generate large quantities of ‘respirable’ fibres (AIOH, 2008). Bonded ACMs not in reasonable condition may also be regarded as friable.

Interferences Fibrous substances that, if present, may interfere with asbestos analysis. Some commonly occurring non-asbestos fibres are “natural organic fibres (such as cotton and hair), synthetic organic fibres (such as aramid, polyester and rayon), man-made mineral fibres (for example, mineral wool and glass fibre), and naturally occurring mineral ‘fibres’ (such as Wollastonite and diatom fragments)” (HSE, 2005 para A2.14), and according to OSHA (1974) fibreglass, anhydrite, plant fibres, perlite veins, gypsum, membrane structures, sponge spicules, and microorganisms.

The use of electron microscopy or optical tests such as polarised light, and dispersion staining may be used to differentiate these materials from asbestos when necessary.

Genotoxic A chemical that induces tumours via a mechanism involving damage to the genetic carcinogen material.

Greenfieldsite A site that has not been previously developed.

Joint and several Where in law two or more parties can be sued for causing the same damage. Each liability party can be liable for a part of the damage (jointly with others) or the whole

amount of the damage alone (severally liable).

Latency period Period between exposure and the onset of asbestos-related disease (ie first appearance of symptoms or diagnosis).

Occupational Exposure that occurs directly as a result of work activities. exposure

Para-occupational Exposure that occurs in household members who live with an occupationally exposure exposed worker, but who are not themselves occupationally exposed. Such exposure

might occur, for example, when laundering contaminated clothing.

Peritoneum Self-lubricating membrane lining of the lower digestive tract and abdominal cavity.

Pleura Self-lubricating membrane lining of the lung and chest cavity.

Prescribed disease A disease arising from a person’s occupation and not a risk common to everybody.

Respirablefibres Respirable fibres are very small fibres (ie <3 µm diameter, usually longer than 5 µm and have aspect ratios of at least 3:1) that can be inhaled into the lower regions of the lung and are generally acknowledged to be most important predictor of hazard and risk for cancers of the lung.

Trace HSE (2005) refers to “trace asbestos identified” where “1 or 2 fibres are seen and identified as asbestos”.


Asbestos in soil and made ground xv

Abbreviations and acronyms

ABS Activity-based sampling

AC Asbestos cement (see Glossary)

ACM Asbestos-containing material

ACOP Approved code of practice

ACS Asbestos-containing soil

AIB Asbestos Insulating Board

AGS Association of Geotechnical and Geoenvironmental Specialists

AIMS Asbestos In Materials Scheme (quality assurance scheme)

ART Advanced Reach Tool

ASM Asbestos source material

ATAC Asbestos Testing and Consultancy

ATSDR US Agency for Toxic Substances and Disease Registry

BAT Best available technology

BOHS British Occupational Hygiene Society

BREF BAT reference documents

CAR Control of Asbestos Regulations 2012

CAS Chemical abstracts service

CDG The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009

CDM The Construction (Design and Management) Regulations 2007

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 1980 (‘Superfund’)

CIEH Chartered Institute of Environmental Health

CL:AIRE Contaminated Land: Applications in Real Environments

CLEA Contaminated Land Exposure Assessment model

CLR Contaminated Land Research reports

CSM Conceptual site model

Defra Department for Environment, Food and Rural Affairs

DETR Department of the Environment, Transport and the Regions

DOE Department of Environment

ED Electron diffraction

EDR Environmental Damage (Prevention and Remediation) Regulations 2009

EDXA Energy dispersive x-ray analysis

ELCR Excess lifetime cancer risk

EPA Environmental Protection Act 1990

EU European Union

GAC Generic Assessment Criteria

HEI Health Effects Institute

HPA Health Protection Agency (now Public Health England)

HSE Health and Safety Executive

HSL Health and Safety Laboratory


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HSWA Health and Safety at Work etc. Act 1974

IARC International Agency for Research on Cancer

ICRCL Interdepartmental Committee on the Redevelopment of Contaminated Land

IOM Institute of Occupational Medicine

JIWG Joint Industry Working Group Asbestos in Soil, Made Ground, Construction and Demolition Materials

LPA Local planning authority

LQM Land Quality Management Ltd

LW Licensable work

MCERTs Environment Agency’s Monitoring Certification Scheme

MMMF Man-made mineral fibre

MPR Maximum permissible risk level (the Netherlands)

NBC Normal background concentrations

NICOLE Network for Industrially Contaminated Land in Europe

NOA Naturally occurring asbestos

NNLW Notifiable non-licensable work

NPPF National Planning Policy Framework for England

NR Negligible risk level (the Netherlands)

OSHA Occupational Safety & Health Administration

PCOM Phase contrast optical microscopy

PHE Public Health England (formerly Health Protection Agency)

PI Professional Indemnity (insurance coverage)

PLM Polarised light microscopy

PPE Personal protective equipment

PRA Preliminary risk assessment

PSD Particle size distribution

RBCA Risk based corrective action

REACH Registration, Evaluation, Authorisation and Restriction of Chemicals

RIVM National Institute for Public Health and the Environment (the Netherlands)

RoGEP Registered Ground Engineering Professional

RSPH Royal Society for Public Health

RPE Respiratory protective equipment

SEM Scanning electron microscopy

SiLC Specialist in Land Condition

SEPA Scottish Environment Protection Agency

SNIFFER Scotland and Northern Ireland Forum for Environmental Research

SNRHW Stable non-reactive hazardous waste

SPOSH Significant possibility of significant harm

TEM Transmission electron microscopy

UKAS United Kingdom Accreditation Service

US EPA US Environmental Protection Agency

WAC Waste acceptance criteria

WHO World Health Organisation

WATCH Working Group on Action to Control Chemicals


Asbestos in soil and made ground 1

1 Introduction

Asbestos is a natural fibrous material. It is known to cause serious illnesses, including lung cancer and mesothelioma. Once thought to be safe, it was widely used for many decades in the UK as a durable, fire-proof and cost-effective material. Historical waste management and demolition practice has resulted in asbestos-containing materials (ACMs) being potentially present in the soil or made ground at any brownfield site. ACMs may have been buried on site intact, broken up and mixed with other demolition wastes, and also potentially imported on site as a contaminant in recycled aggregates/made ground materials. Asbestos cement wastes were also used to improve paths and farm tracks on otherwise greenfield sites.

As the health effects became known, legal controls to protect the health and safety of workers and the public developed. For example, Regulation 16 of the Control of Asbestos Regulations 2012 (CAR) imposes a duty on every employer to “prevent or, where this is not reasonably practicable, reduce to the lowest level reasonably practicable the spread of asbestos from any place where work under his control is carried out”. Other current relevant legislation includes the Construction (Design & Management) Regulations 2007 (CDM) and the Health and Safety at Work Act 1974 (HSWA). These also extend to asbestos found during site reconnaissance visits, ground investigations and other similar activities.

The numbers of deaths from asbestos-related diseases in the UK has risen in recent decades – mesothelioma is no longer a rare form of cancer in the UK. There continues to be unintentional exposure to asbestos in the UK, especially in the construction and building maintenance sectors. To try to prevent such exposure, publicity campaigns (notably the HSE Hidden Killer campaign, see Useful websites) have raised awareness among workers and there continues to be a need to ensure that all workers are alerted to the hazards, including those posed by asbestos-containing soils (ACSs). However, such publicity has resulted in widespread fear of asbestos among the public such that the mere presence of asbestos can result in disproportionate alarm. Consequently, taking account of the risks perceived by workers and the public is important when dealing with ACSs.

Land contamination is considered in risk-based land management frameworks embedded in a wide range of legislation that seeks to protect human health and the environment. The starting point of any risk assessment is the legal context within which the assessment is being carried out coupled with the conceptual site model (CSM) of exposure (SNIFFER, 2007). The Environment Agency (2004) provides a step-wise approach to carrying out risk assessment and remediation.

Although there is considerable guidance on investigating, assessing, and managing occupational exposure to asbestos, there is limited guidance on assessing and managing environmental or non-occupational risks from asbestos in the ground in the context of, for example, common law, planning or Part 2A of the Environmental Protection Act 1990. In addition to addressing non-occupational risks, there is also a need to sign-post existing occupational guidance documents/requirements on asbestos for those undertaking ground investigations.

Recent changes to the Part 2A regime in England and Wales and a review of the regime in Scotland make it timely to provide guidance on risk assessment under Part 2A. Recent court rulings have refined the understanding of liability under the tort of negligence and have implications on risk assessment aimed at ensuring new development is suitable for use.

In compiling this guide, national and international guidance and practice, as well as the limited scientific literature and available case studies, have been reviewed in order to form a defensible evidence base. This review has also allowed the identification of critical gaps and uncertainties in the present understanding of the risks posed by asbestos in soil and made ground.


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1.1 AImThe aim of this guide is to improve the confidence in and performance of risk assessment and risk management on sites that contain soils or made ground potentially contaminated by asbestos.

1.2 ObjeCtIveSThe overall objectives of this guide are to help practitioners:

�� understand the risks to health posed by asbestos that may be buried in the ground or dispersed within soils and made ground

�� know how to comply with relevant legislation when managing sites where asbestos may be present in the ground or soil, including the Part 2A and planning regimes, the Control of Asbestos Regulations 2012, relevant codes of practice, duty of care, and hazardous waste obligations

�� know how to comply with the civil liabilities in negligence and nuisance

�� plan effectively for dealing with the possibility of asbestos in any field investigation including advice for desk studies and preliminary site surveys

�� know what options are available if asbestos is discovered on-site

�� know what to look for and the requirements for laboratory testing including a discussion of ACM and the identification/quantification of asbestos fibres in soil and made ground

�� understand how the tiered approach to the risk assessment applies to asbestos taking into account the legislative context

�� know and assess the advantages and limitations of various remediation approaches through different project scenarios

�� understand the importance of multi-disciplinary teams to the investigation, assessment and remediation of sites affected by asbestos

�� know how and when to appoint and manage specialists and how to ensure that they will follow good practice

�� specify and record adequate monitoring

�� keep verification reports and records of asbestos known to be present in specific media and locations.

1.3 StRuCtuRe Of the GuIdeThis guide consists of two main parts:

Part 1 (Chapters 3 to 9) contains essential background information and forms the basis for Part 2

Part 2 (Chapters 10 to 17) contains more practical information on the methods and procedures used in the assessment and management of affected sites.

In order to understand the relevance of the methods and procedures and to appreciate the sources of uncertainty involved in Part 2, it is important that readers have a thorough understanding of Part 1. Each chapter starts by stating what it aims to achieve and concludes with a summary of the key findings.

Chapter 2 comprises a short summary of requirements for the assessment and management of risks from ACSs. This is intended to help clients, landowners or developers appreciate the technical and legal issues associated with ACSs and to increase their awareness of what is involved in the appropriate investigation, assessment, remediation and management of asbestos in soil. However, it is not intended as an alternative for consultants and other professionals to reading the detailed guidance contained in Parts 1 and 2.



Part 1Chapter 3 describes the relevant legislation

Chapter 4 outlines the legal and mineralogical definitions of asbestos and the range of products containing asbestos.

Chapter 5 describes the effects on human health of asbestos inhalation.

Chapter 6 summarises the types and potential magnitude of exposures to inhalable asbestos in the UK.

Chapter 7 summarises practices in other countries.

Chapter 8 addresses compiance with CAR 2012: risk assessments, licensing and training.

Chapter 9 reviews the release of airborne fibres from asbestos in soil.

Part 2Chapter 10 outlines the requirements for preliminary risk assessment, including the role of the conceptual site model.

Chapter 11 describes the sampling and analysis of soils containing asbestos.

Chapter 12 describes air monitoring and the analysis of asbestos in air.

Chapter 13 describes the process of exposure assessment and how potential airborne fibre concentrations may be estimated.

Chapter 14 describes the process of risk estimation and risk evaluation under specific legal regimes.

Chapter 15 summarises management and remediation options.

Chapter 16 discusses good practice approaches to communicating the potential risks to the public and other stakeholders of identifying asbestos in soils at a site.

Chapter 17 identifies issues to consider when appointing specialists.

Chapter 18 draws general conclusions about current understanding and gaps in knowledge of asbestos in soil and made ground, including recommendations for future work.

1.4 WhAt ARe ‘SOIl’ And ‘mAde GROund’?Within this guide ‘soil’ is used to mean both naturally occurring and man-made unbound mixtures of solid particles of varying size and composition at various moisture levels. Man-made soils are generally referred to as ‘made ground’ and when engineered to a specification are referred to as ‘fill’.

Made ground has been artificially deposited on the former, natural ground surface. It includes engineered fill (such as road, rail, reservoir and screening embankments), flood defences, spoil (waste) heaps, coastal reclamation fill, offshore dumping grounds, constructional fill (eg bunds, landrise), and infilling of excavated voids, such as pits, quarries, opencast sites (Rosenbaum et al, 2003). Associated terms include ‘landscaped ground’ where remodelling of the original ground surface obscures the boundary between excavated and infilled ground. Basements, old tanks, gas holder bases and other voids were commonly used to dispose of demolition and other debris on clearing a site. In the 1970s such spaces were often specifically used to dispose of asbestos-contaminated materials.


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1.5 leGAl COntextThe approach taken to the characterisation and assessment of risks relating to ACSs will be heavily influenced by the legal context. Existing developments are likely to be assessed under Part 2A of the Environmental Protection Act 1990 (see Section 3.3.2). For land to be declared as contaminated under this regime, local authorities need to show either that significant harm is being caused or that there is a significant possibility of significant harm (SPOSH). In the planning process for new developments (see Section 3.3.1), if soil contamination is identified as an issue, responsibility for securing a safe development rests with the developer and/or landowner. Under both contexts, the local authority acts as the primary regulator with reference to land contamination either via environmental health officers or specialist contaminated land officers.

Unless otherwise stated the discussion in this guide focuses on the situation as it pertains to England after April 2012. Specific reference is made to the situation in Scotland, Wales and Northern Ireland.

It should be noted that planning and Part 2A legislation differ between the four countries of the UK. The Control of Asbestos Regulations 2012 apply in England, Wales and Scotland, and in Northern Ireland the Control of Asbestos Regulations (Northern Ireland) 2012 apply.

Civil law (here contract and tort) requires work to be done as accurately as is reasonably possible and also imposes duties to take reasonable care of those who might be affected by works, which includes practitioners, contractors, the public, developers, landowners and other stakeholders.

Standards for what is an acceptable asbestos exposure have become more stringent over the past 50 years. For example, a quantitative occupational exposure limit for asbestos was first introduced into the UK in 1960. That limit has, in effect, become 300-times more stringent over the past 50 years. Given the ongoing concern surrounding asbestos and the incidence of asbestos-related disease, it is also possible that the acceptable criteria for asbestos in soils will progressively tighten in the future.

It is possible that criteria used to define SPOSH under Part 2A may change during the probable lifetime of developments that are currently being constructed. As additional remediation of ACSs post-development is generally hugely expensive, developers may wish to adopt a precautionary approach (additional voluntary remediation) to the assessment and remediation of ACSs during any development.

1.6 unItS Of meASuRementA variety of different units are used within the literature cited in this guide relating to asbestos concentrations in soil and air. Within this guide values have been cited in the same units as the source. Where the reader needs to make comparisons, units can be easily inter-converted as shown in Table 1.1. The concentration of asbestos in soil and made ground is expressed in terms of the weight of asbestos per unit weight of soil calculated on a dry weight basis. It is usually reported as a percentage by weight but can also be expressed in mg/kg. The concentration of asbestos in air is usually reported in terms of the number of fibres per unit volume in units of fibres per millilitre of air or fibres per cubic metre of air (Table 1.1). In this guide units of f/ml are used unless the source document does otherwise.



Table 1.1 Conversion between standard units used for soil concentrations (milligrams per kilogram soil (mg/kg) and percentage asbestos by weight (%)) and air concentrations (fibres per millilitre (f/ml) and fibres per cubic metre (f/m3))

mg/kg % f/m3 f/ml

10 000 1% 1 0.000001

1000 0.1% 10 0.00001

100 0.01% 100 0.0001

10 0.001% 1000 0.001

1 0.0001% 10 000 0.01

0.1 0.00001% 100 000 0.1

0.01 0.000001% 1 000 000 1

note

Fibres per millilitre (f/ml) and fibres per cubic centimetre (f/cc; f/cm3) are synonymous.

The health risks from airborne asbestos are usually associated with cumulative exposures, which are representative of the accumulated fibre burden inhaled into the lungs. Cumulative exposures are usually estimated as the product of the airborne fibre concentration (usually in f/ml) and the period of exposure (eg in hours or years) and reported as f/ml.hours or f/ml.years. The calculation of cumulative exposures is described in detail in Chapter 13.

1.7 funCtIOn And lImItAtIOnS Of the GuIdeThis guide provides coherent information for clients, landowners or developers and their advisors, regulators and other stakeholders on the safe investigation, assessment and remediation of soil and made ground containing, or suspected of containing, free asbestos fibres or ACMs.

It may be used by clients to inform procurement and by professional advisors in demonstrating adherence to good practice. Chapter 2 has been written specifically with clients in mind. It contains a distillation of the key messages of the whole guide.

Phrases such as ‘risk assessment’ and ‘assess the risk’ have multiple interpretations within this guide. The authors have tried to discriminate between ‘health and safety risk assessments’ required under occupational health and safety legislation (such as HSWA and CAR) and ‘soil risk assessments’ needed under development control, Part 2A or other environmental legislation. Both are equally important with respect to the aims of this guide. However, where the distinction is not explicit, the reader will need to infer the appropriate context.

This guide is intended to be read and referred to by practitioners and their clients, landowners or developers, by regulators, policy makers, project managers and other stakeholders. It contains a digest of contemporary information and guidance with the aim of raising current good practice. CIRIA guides are widely recognised as being authoritative and robust but they are only to be used as guidance and have no legal standing per se.

The guide does not seek to be the code of practice being developed by the EIC-CL:ARE Joint Industry Working Group on Asbestos in Soil, Made Ground and Construction & Demolition Materials.

This guide does not include detailed comment on all legal source material – the law changes over time. Also, it should be used only as a starting point when evaluating legal duties and responsibilities, and further research will be necessary.

This guide is up-to-date at the time of writing (2014), however the user should check for any changes in regulations or statutory guidance as well as keeping track of scientific and technical developments.


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2 Client requirements for assessment and management of risks

The term ‘asbestos’ refers mainly to six fibrous minerals that are known to cause serious health effects when inhaled. The main commercially-exploited forms are chrysotile (white asbestos), amosite (brown asbestos) and crocidolite (blue asbestos).

Unlike some parts of the world, including parts of California, USA, naturally occurring asbestos (NOA) is not commonly found in UK soils but in the past large volumes of asbestos have been imported. Between 1900 and 1980, asbestos was widely used in a plethora of construction and insulation products due to the physical, thermal and chemical properties of the fibres. The importation of crocidolite had ceased by 1970 (except for limited specialised applications such as battery casings). The importation of amosite ceased in 1980. The importation and use of asbestos in the UK was finally banned (for nearly all purposes) in 1999.

Robust science has demonstrated that exposure to asbestos fibres in air is linked to a number of fatal conditions, and is currently responsible for about 4500 deaths annually in the UK. There is no known safe threshold of exposure to airborne asbestos, but the risk is proportional to the level of exposure. It is widely accepted that (usually small amounts of) asbestos are commonly encountered during the development of urban brownfield land. However, due to the lack of available policy, guidance and assessment criteria, assessment of asbestos on redevelopment sites to date has been variable across the industry.

2.1 leGISlAtIOn And pOlICyThe protection of workers and the general public from exposure to asbestos from work activities is regulated by the Control of Asbestos Regulations (CAR) 2012. Among other things it requires employers (and clients) to ensure exposures are prevented or minimised through the use of appropriate risk assessments and the adoption of appropriate control measures. This legislation applies to any work commissioned in relation to ACSs, including site investigations and remediation works. Additional requirements are imposed by other legislation such as the Construction (Design and Management) Regulations 2007 (CDM).

ACSs could also result in common law liability for clients and landowners if ‘negligence’ triggers the ‘ joint and several liability’ provisions of the Compensation Act 2006, which makes specific provisions for asbestos. Clients and landowners with responsibilities for ACSs may also incur liabilities under contaminated land legislation, such as Part 2A of the Environmental Protection Act 1990, or redevelopment legislation (ie the planning process). Note that the contaminated land regime is designed to address very serious problems, whereas liabilities to humans for exposure dealt with under common law can consider much lower levels of risk to be a breach of the duty of care. Releases of asbestos into soil after March 2009 could be regulated under the Environmental Damage Regulations 2009.

AimThis chapter distils key points described in this guide, to provide clients, landowners and problem holders etc with an overview of what is needed to effectively manage asbestos in soil and made ground. It does not contain sufficient detail for consultants, contractors or advisors upon which to formulate their advice, procedures and methods. Notable issues include health risks, commercial risks, legal duties, assessment procedures and techniques, the roles of specialists and the decision making process. Asbestos is a common and important contaminant in soil and made ground. Its presence in soils is particularly challenging in several ways. Asbestos is very durable and will remain as a contaminant in soils indefinitely unless remediated, and may become more available when and if materials that contain asbestos degrade in the soil leading to a greater potential for release into the air.



The guide also endeavours to make clients aware of the duties placed on them, and their contractors, by waste legislation, and the carriage and labelling requirements regarding materials containing or suspected of containing asbestos, including ACSs.

2.2 exIStInG uK And OtheR nAtIOnAl GuIdAnCe On ASbeStOS In SOIl And mAde GROund

Health and Safety Executive (HSE) guidance on asbestos, while not directly related to soil, is still useful, informative and sometimes sets a standard.

This guide is part of an ongoing joint industry initiative to develop understanding, guidance and eventually a code of practice on the management of asbestos in soil, made ground and demolition debris.

Now outdated UK-specific guidance relating to ACSs was issued by ICRCL (1990). This highlighted that levels of airborne asbestos in excess of the then occupational exposure limits can, in some circumstances, be generated from soils containing very low levels of asbestos (ie <0.001 per cent). However, this guidance is now largely outdated and has been superseded by other international research and guidance.

Guidance specifically relating to asbestos in soils has also been published by several organisations in the USA, the Netherlands and in Western Australia. Although technically informative, much of this guidance is driven by national and state policy and legal considerations and so is not directly applicable in the UK (see Chapter 7).

The Association of Geotechnical and Geoenvironmental Specialists has published interim guidance on protecting workers and the public during site investigations (AGS, 2013).

2.3 heAlth effeCtSInhaling asbestos fibres significantly increases the risk of asbestos-related diseases, particularly lung cancers and mesothelioma (see Chapter 5). There is a long latency period (usually more than 20 years) between exposure to asbestos and the onset of such cancers. Because airborne asbestos fibres are very thin and are not visible to the naked eye, asbestos is often referred to as the ‘invisible killer’ in the media (most notably in the eponymous HSE campaign, see Useful websites).

2.4 humAn expOSuReS tO ASbeStOSThe extensive use of asbestos has resulted in low, but detectable, background concentrations of airborne asbestos fibres in the UK and other industrialised countries, especially in urban areas.

Background levels are likely to be declining due to the cessation of use, the removal and disposal of ACM from the built environment, and improved controls during removal. These low level exposures may be important as there is evidence that low or unrecognised exposures to asbestos may be responsible for significant numbers of mesothelioma cases each year in the UK (Peto et al, 2009).

Historically, regulatory effort focused on minimising the exposure of workers in the asbestos manufacturing and other high risk industries. In the last 20 years, attention has been on the construction industry, which accounts for nearly half the current incidence of mesothelioma in the UK. Currently, asbestos in soil is not given the same degree of attention as ACM in buildings but could become a recognised source of exposure in the future.

Exposure to asbestos is expressed in terms of the concentration of asbestos fibres in air (fibres/ml) and the duration of exposure (eg hours) giving a cumulative exposure (in fibre/ml.hours). Exposure concentrations from work activities on ACMs could range widely, and many activities were associated with concentrations of 1 to 20 fibres/ml with some activities producing much higher concentrations.


CIRIA, C7338

Naturally-occurring asbestos is not commonly found, in the UK but large quantities of asbestos were imported. So almost all current and future asbestos exposure will arise from the ongoing presence of ACMs either as soil contamination or in the built environment.

2.5 ReleASe Of AIRbORne fIbReS fROm ASbeStOS-COntAInInG SOIlS

Asbestos fibres are hazardous and pose a health risk when released into the air and inhaled. In general, higher concentrations of asbestos in soil have the capacity to liberate higher concentrations of asbestos fibres into the air but this is also very dependent on the type of ACM present and its ability to release fibres.

Free asbestos fibres at the surface can become airborne due to wind (usually a minor consideration) or by physical disturbance during either site development (eg construction, remediation or earthworks) or site use (eg gardening and children playing). Soil moisture, particularly on the surface, is a major inhibitor of fibre release. Other factors that will reduce the release of airborne dust and fibres include dense vegetation or other coverings such as paving slabs or tarmac (see Chapter 9).

Release of asbestos fibres from ACMs is determined by the friability of the original ACM and the degree of degradation and wear. For example, lagging and asbestos insulating board (AIB) may deteriorate relatively quickly but the degradation of firmly bound materials (eg asbestos cement) may take a very long time (see Chapter 9). Research is needed to determine the rate and potential significance of such degradation (see Chapter 18).

2.6 COmplyInG WIth the COntROl Of ASbeStOS ReGulAtIOnS

Where work involves (or is likely to involve) contact with asbestos, then CAR 2012 requires a risk assessment, including whether or not the work is licensed or notifiable non-licensed work, to be made. CAR will require some remediation work (eg where asbestos in soil is a remediation driver) and occasionally work involved in site investigations (eg where asbestos is known to be present) to be licensed work (LW) and undertaken by licensed contractors. Investigations and remediation on some other sites may involve notifiable non-licensed work (NNLW).

All staff likely to encounter asbestos at work require appropriate information, instruction and training to comply with CAR. Additional proficiency training is likely to be required, for example to ensure staff can identify potential ACMs in soil and made ground. Generic training on work in ACSs would help ensure that the requirements of CAR are followed, but site specific training may be needed. Factors to be considered include the tasks undertaken, amount and nature of asbestos in the ground, the ground conditions, and an individual’s previous experience and training.

2.7 AppOIntment Of SpeCIAlIStSEffective management of ACSs may require a multi-disciplinary team comprising contaminated land specialists and asbestos specialists. In order to form and benefit from such teams, the client needs an outline understanding of the issues involved, a clear idea of the investigation or remediation objectives and the required outcomes.

This guide is intended to provide clients with the understanding needed to commission such projects and to assist individual specialists and practitioners to discern the complexities associated with managing ACSs.

Any contaminated land risk assessment should consider all potential contaminants of concern, which may include asbestos. Where asbestos is a potential contaminant of concern, additional skills, experience and competencies may be required in order to adequately investigate and assess the potential risks



while complying with CAR. Contaminated land practitioners will be needed at all sites, but may require varying degrees of input from asbestos specialists depending on the nature of the site. Significant input from asbestos specialists may be required at sites where asbestos is a major contaminant and/or the type(s) and form(s) of asbestos present may pose elevated levels of risk. Such sites may best be addressed by a multidisciplinary team rather than an individual consultant. Clients need to provide a clear specification for the investigation, including its aims and scope of works, and look for evidence that the appointed contractors have the relevant training, knowledge, competencies and experience appropriate for the site under consideration.

Under CAR, clients have legal duties that cannot be delegated. Clients, consultant(s) and contractor(s) must work together as a team to effectively investigate, assess and manage any risks relating to ACSs. Clients who attempt to delegate responsibility to the consultant may find they are in breach of legislation and fail to fully understand the liabilities and costs involved.

2.8 pRelImInARy RISK ASSeSSment (pRA) And develOpInG the COnCeptuAl SIte mOdel (CSm)

It should be noted that a ‘greenfield’ site does not necessary imply there is no asbestos contamination.

The potential for ACSs to be present should be considered during the PRA at all sites unless adequate justification for not doing so can be documented (eg are records of the pre-demolition survey available and records of any subsequent asbestos removal and disposal?). This is in-line with former Department of the Environment DOE Industry profiles and CAR although further guidance is needed on this (see Chapter 18).

It should also be noted that CAR and associated guidance primarily concerns asbestos in buildings and does not explicitly mention asbestos in soils. However, CAR does specifically cover the ‘curtilage’ of a building, which legally includes the soil at the site. Decisions regarding whether CAR applies and whether asbestos is a contaminant of concern should be made on a site-by-site basis.

The potential presence of ACSs should be considered during the PRA at all sites. A summary of the process is shown in Figure 2.1. Some specific industries are known to be associated with significant asbestos contamination but a much larger number of sites have lower levels of asbestos associated with demolition activities, waste deposition and/or illegal dumping.

Having established the legal context, a PRA is carried out by “develop[ing] an initial conceptual model of the site and establish[ing] whether or not there are potentially unacceptable risks” (Environment Agency, 2004). Without an effective conceptual site model (CSM) it is not possible to design a field investigation that will adequately and robustly characterise the potential risks posed by ACSs.

A robust PRA should include both a desk study and a site reconnaissance survey to explore the likelihood that ACSs are present. If there are grounds for believing that asbestos may be present, the site reconnaissance must be conducted in accordance with CAR 2012 by appropriately trained and experienced personnel.

Information on the age of demolished structures, details of any development and/or refurbishment work that may have taken place and information on when and how they were demolished may allow the likelihood of asbestos contamination in arisings to be assessed. However, where insufficient information is available, on a precautionary basis asbestos should be considered a potential risk driver at the site.

Clients should ensure that work specifications require that the potential for ACSs is adequately addressed during any desk study and site reconnaissance, that CAR 2012 will be complied with and that any report will provide sufficient details to plan, design and implement any subsequent site investigation works.


CIRIA, C73310

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ract

eris

tics

of th

e si

te a

nd it

s se

ttin

g

Is a

sbes

tos

unlik

ely

to b

e pr

esen

t in

soils

?

Step

4b

Asb

esto

s is

not

a m

ajor

contam

inantofconcern(CoC).

Upda

te c

once

ptua

l mod

el

and

pollu

tant

link

ages

Step

5b

Cond

uct r

econ

nais

sanc

e vi

sit i

n re

latio

n to

oth

er C

oC

Step

5a

Cond

uct r

econ

nais

sanc

e in

rela

tion

to a

ll Co

C, in

clud

ing

asbe

stos

CAR

app

lies

to re

conn

aiss

ance

vi

sit .

Prep

are

suita

ble

risk

asse

ssm

ent a

nd m

etho

d st

atem

ent

Step

4a

Asbe

stos

is a

maj

or C

oC . U

pdat

e co

ncep

tual

mod

el a

nd p

ollu

tant

link

ages

StO

p W

OR

K!

Impl

emen

t em

erge

ncy

proc

edur

es to

preventexposureandre-evaluaterisks

No

furt

her a

ctio

n w

ith

resp

ect t

o as

best

os

Go

to e

xpos

ure

estim

atio

n/ris

k ev

alau

atio

n

Is a

sbes

tos

unlik

ely

to

be p

rese

nt in

soi

ls?

Is a

sbes

tos

poss

ibly

pr

esen

t in

soils

?

Is a

sbes

tos

high

ly li

kely

to

be

pres

ent i

n so

ils?

Is a

sbes

tos

know

n to

be

pres

ent i

n so

ils?

Is u

nexp

ecte

d as

best

os

enco

unte

red

durin

g re

conn

aiss

ance

vis

it?

Yes

No

Yes

No

Yes

No

Yes

Yes

Don

’t kn

ow

No



2.9 SOIl SAmplInG And AnAlySIS Of ASbeStOS In SOIlCAR 2012 places legal duties on clients commissioning work at sites where ACSs may be present. Specifications should ensure that potential contractors are suitably qualified and experienced, and are aware of the requirements of CAR 2012 (including the use of suitably accredited testing) and any notification or licensing requirements.

Normal site investigation techniques, such as boreholes, trial pits, trenches etc, can be used for ACSs but it is important that site workers are protected and CAR 2012 is complied with. A range of analytical methods for the identification and quantification of asbestos in soil are available from UK laboratories and contractors. However, analytical methods are still being developed both in the UK and elsewhere. For example, ‘fibre release potential tests’ measure the ability of ACSs to release airborne fibre. This may represent a better basis for exposure estimation than simple quantification of asbestos in soil. Such tests are currently available in the UK but on only a limited basis.

Careful consideration of the objectives of the investigation is needed to ensure a suitable quantity and quality of data is obtained, particularly where the data will be used to inform an assessment of potential risks. If the analysis goes beyond the requirements of CAR, then laboratories may be able to undertake additional tests that help assessments under, for example, the planning or contaminated land regimes.

2.10 AIR mOnItORInG And AnAlySIS Of ASbeStOS In AIRModelling techniques that allow potential airborne exposures to be estimated from soil concentration data do exist. However, due to uncertainties associated with such estimates, additional lines of evidence are often needed to support any exposure assessment. This may include direct measurements of asbestos fibre concentrations in outdoor and/or indoor air and dust (ie if the tracking back of soil-derived asbestos fibres is suspected). However, such measurements do not account for increases in future exposure due to the deterioration of ACMs or changes in exposure due to changes in ground profile.

There are internationally accepted technical standards for the sampling and analysing of asbestos in air in the work place. Air is drawn through a filter at a known flow rate for a known period of time. The filter is treated in a manner appropriate to the analytical method to be used and fibres are identified and counted manually using phase contrast optical microscopy (PCOM). Such methods normally provide a limit of quantification (LoQ) of ~0.01f/ml (fibres of asbestos per millilitre of air) and provide poor fibre discrimination (eg non asbestos fibres can be counted as asbestos fibres). Such methods are not sufficiently sensitive or selective for assessing environmental exposures but may suffice for perimeter monitoring as a first check that fibre concentrations during remediation do not exceed legal limits. However, perimeter monitoring to demonstrate that airborne asbestos concentrations are not significantly increased by site activities will require methods with a much lower LoQ.

Background concentrations in the general environment can be 0.0001f/ml or less (eg WHO, 2000, Shuker et al, 1997). Assessing potential risks associated with long-term exposure to such environmental concentrations (such as required to demonstrate suitability for use under the planning regime) requires measurements with lower LoQ and better fibre discrimination capability than are offered by such occupational monitoring. However, some UK suppliers do have the relevant accreditation to provide suitable methods, which generally involve modification of the flow rate, flow duration and/or the use of transmission electron microscopy (TEM) or scanning electron microscopy (SEM). TEM and SEM can visualise finer fibres and better discriminate between asbestos and non-asbestos fibres (which are common in environmental samples) and between the different types of asbestos fibres.

Clients should ensure that work specifications clearly state the requirements for any air monitoring and that it has appropriate accreditations to comply with CAR 2012. It should also ensure that any contractors are suitably trained and experienced.


CIRIA, C73312

2.11 expOSuRe eStImAtIOnIn order to estimate risk, it is necessary to estimate the exposure to airborne asbestos that workers, residents, or children may realistically receive, based on available soil and air sampling data.

Such estimates may be calculated from air monitoring, fibre release tests or from soil concentration data using predictive modelling. Because each strategy has strengths and weaknesses, a ‘lines of evidence’ approach involving more than one exposure assessment strategy is often required in order to produce a robust exposure estimate.

Laboratory-derived soil-to-air relationships (such as those based on Addison et al, 1988) can be used to predict airborne fibre concentrations based on soil measurements, which can inform site specific quantitative risk assessments. The use of such soil-to-air relationships can take account of the deterioration of the ACM, the likely soil dust in air concentrations, the type of soil, and the type of asbestos using qualitative assumptions. Considerable uncertainty exists in such estimates, particularly at low soil concentrations, but such modelling may be the only way to assess exposures that are likely to arise (eg from proposed use or future activities).

2.12 RISK eStImAtIOn And evAluAtIOnModels can correlate exposure to airborne asbestos with risk based on the rates of mesothelioma and lung cancer seen in workers historically exposed to asbestos in factories and mines. These models are extrapolated to predict the health risks (ie excess lifetime cancer risks) associated with long-term exposure to the lower airborne asbestos concentrations that may be associated with ACSs. The predicted health risk can then be assessed against legislation-specific criteria to indicate its acceptability or otherwise, and hence the need for risk management. For example, under Part 2A the local authority needs to be satisfied that intervention is justified and under planning the developer has to demonstrate a site is safe for its intended use.

Where the PRA shows that the risks may be of concern, a detailed quantitative risk assessment (using exposure-risk models) will be required (Figure 2.2) since there are currently no suitable UK generic assessment criteria for asbestos in soil. As generic assessment criteria needs to be “produced in an objective, scientifically robust and expert manner by reputable organisations” (Defra 2012a), the hazardous waste threshold (see Section 3.6) and the value of 0.001 per cent mentioned by ICRCL (1990) should not be used in this capacity (see Section 7.1).

Exposure-risk models can predict the likely health effects of exposure to airborne asbestos. Decisions or recommendations regarding the acceptability or unacceptability of the estimated risks produced using such models should take full account of the considerable uncertainties involved. Any reports should fully describe and justify the assessment process used and the uncertainties, with reference to the specific legal context.



Figu

re 2

.2

Flow

char

t of a

risk

est

imat

ion

and

risk

eval

uatio

n pr

oces

s

from

pha

se 1

Step

1Confirm

ou tlineconceptual

m

odel

and

con

text

of R

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3Defineinform

ationandlines

of e

vide

nce

need

ed to

sup

port

DQRA(seeChapters 12

and13)

Ris

k co

mm

unic

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n?

Rec

ord

in a

sbes

tos

regi

ster

?

Com

ply

with

HSE

requ

irem

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no

furt

her a

ctio

n(updateconceptualmodel

and pollutantlinkages)

Rev

iew

con

text

, crit

eria

and

in

form

atio

n to

dec

ide

next

ste

p

Is it

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able

and

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st e

ffec

tive

to c

olle

ct a

ll in

form

atio

n/lin

es o

f evi

denc

e?

CAR

app

lies

to s

ite w

orks

. Pr

epar

e su

itabl

e ris

k as

sess

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ts a

nd m

etho

d st

atem

ents

No

GAC

for a

sbes

tos

avai

labl

e in

the

UK .

Det

aile

d qu

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ativ

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k as

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t req

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d

Step

8Ev

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isks

ta

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acc

ount

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tabl

ish

eval

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n cr

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(seeSection15

.6)

Step

6Es

timat

e ris

ks a

ssoc

iate

d w

ith s

uch

pote

ntia

l exp

osur

es

(seeChapter15)

Step

5Es

timat

e ex

posu

re o

f po

tent

ial r

ecep

tors

to

airborneasbestosfibres

Step

4Co

nduc

t site

wor

ks to

col

lect

in

form

atio

n an

d ot

her l

ines

of

evidenceidentifiedinStep3

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Go

to o

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ns a

ppra

isal

(asdescribedinCLR11

)

No

Yes

Cons

ider

wha

t fur

ther

risk

as

sess

men

t is

need

ed

No

Yes

No

Yes

No

Don

’t kn

ow

Yes

Step

2Define/refineobjectivesf orR

A


CIRIA, C73314

2.13 RemedIAtIOn And mAnAGementAs asbestos fibres are effectively chemically and biologically inert, the remedial options for ACSs are limited, mainly involving removing the asbestos, capping or physical processing of the soils. Available remedial approaches in the UK are described in Chapter 15, together with some potential emerging technologies.

Historically, the default action at many sites has been to remove any ACSs, which can be costly and may increase the risks to workers and the public. Increasingly the default is to reuse material on site using the Definition of waste: Development Industry Code of Practice (CL:AIRE, 2011). However, several alternative remedial approaches are currently available in the UK. Some of these approaches are potentially applicable to a wide range of contaminants in addition to asbestos (eg cover systems and capping, soil washing and solidification). The potential drawbacks, such as ongoing liabilities, property blight and potential health and safety concerns, need to be carefully evaluated during the options appraisal process. Another key consideration will be the attitude and stance of the relevant regulators, including the relevant local authority and environmental protection agency (ie Environment Agency, Natural Resources Wales, Scottish Environment Protection Agency, and Northern Ireland Environment Agency). There can even be variation within the different agencies, regional offices or even between different individuals in such organisations. So, early and continued consultation and discussion with the relevant regulators is essential.

Careful verification of any remedial action is likely to be critical in maintaining public confidence. Following remediation, any residual liability can be addressed using financial liability transfer mechanisms, such as insurances etc.

2.14 RISK COmmunICAtIOnRisk communication comprises the formal and informal processes of communication among various parties who are potentially at risk from or are otherwise interested in the site. Due to the public perception of asbestos, even low concentrations of asbestos in soil have the potential to cause property blight, commercial risks and reputation damage for organisations and individuals. It is particularly important that clients are aware of the importance of risk communication with respect to sites where there is asbestos in soil. This may require input from qualified public communication and media relations specialists.

US EPA (1988) gives ‘seven cardinal rules’, which are relevant to asbestos as well as to other land contamination issues:

Rule 1 – Accept and involve the public as a legitimate partner.

Rule 2 – Listen to the audience.

Rule 3 – Be honest, frank, and open.

Rule 4 – Co-ordinate and collaborate with other credible sources

Rule 5 – Meet the needs of the media.

Rule 6 – Speak clearly and with compassion.

Rule 7 – Plan carefully and evaluate performance.

2.15 COnCluSIOnSAsbestos only becomes a risk to health when and if it becomes airborne, and where people are exposed to the airborne dust. The health effects from asbestos inhalation are well recognised. Poor demolition and material handling practices in the past mean asbestos contamination in soils and made ground is commonplace.



Detection and especially quantification of asbestos contamination is not easy but it is important that it should be done well. Asbestos contamination is very durable and it will remain in soil. Many common ACMs may degrade if left in soils or made ground leading to more asbestos fibres being released in the future.

Where asbestos is present in gross quantities, deciding that remediation is needed is relatively straightforward.

Where asbestos is present in significant but variable quantities, then more careful investigation may be needed to assess the extent and level of its presence. Modelling techniques are available to estimate the potential for asbestos fibres to become airborne from asbestos in soils and cause exposure to humans. However, such models contain considerable uncertainty as they are based on limited laboratory experimentation.

Scientific links between health effects and exposure to asbestos offer a sound basis for assessing the potential risk from estimated, modelled or measured airborne exposures from asbestos in soil. However, there are uncertainties in such predictions. Demonstrating that a site is safe for its intended use under planning may need to consider the upper limit of the risk predictions while such an approach may not be compatible with the Part 2A contaminated land regimes. In either case, it is important to realise that substantial civil liabilities can arise from making only a small contribution to the risk of any subsequent mesothelioma victims.

It is easier and less expensive to deal with asbestos contamination in the early stages of a development than later on when access to a site becomes more complex and restricted. Good use of skilled multi-disciplinary teams of contaminated land and asbestos specialists is recommended.

There are several areas where additional research effort is needed to reduce important uncertainty. However, until such time as robust real world data are available, the present knowledgebase provides a defensible basis for understanding and managing the risks to human health posed by asbestos in soil under a variety of legal contexts across the UK.


CIRIA, C73316



part 1understanding the risks of asbestos in soil and made ground


CIRIA, C73318

3 legislation relating to asbestos in soil

3.1 IntROduCtIOnThis chapter provides an outline of the UK legislation, and recent case law, to guide the technical practitioner in general terms. It is intended to be read in conjunction with the legislative documents and guidance, and aims to signpost key issues that are important in dealing with asbestos-containing land. It does not contain the regulations that apply specifically to licensed asbestos contractors. Where such specialists are retained, readers should supply them with all relevant information that they hold and rely on their expertise. It is also necessary to ensure that appropriate health and safety risk assessments and method statements are prepared for the work and amended when situations change during the project.

A wide range of legislation applies to ACSs (Table 3.1), and this varies from country to country within the UK. Readers should refer to the primary and secondary legislation and any judgments that may become available as well as to relevant approved codes of practice (ACOPs) and guidance for full details of current legislation and/or seek professional advice. In addition to statutes, a range of civil and case law is applicable to ACSs. Readers should presume the law relates to England only unless stated otherwise. On a given site, different legal contexts can apply both consecutively and/or simultaneously. This brief commentary is intended to alert the reader to the issues that may need further consideration.

The following commentary is based on the law as it applies to England. Equivalent provisions apply in the other three countries unless explicitly stated. These provisions are listed in Table 3.1. The law changes over time, so it is important that the reader regularly checks for the most up-to-date legislation.

ACOPs have a special legal status. If employers are prosecuted for a breach of health and safety law, and it is proved that they have not followed the relevant provisions of the ACOP, a court can find them at fault unless they can show that they have complied with the law in some other way.

The HSWA 1974 gives the Secretary of State power to issue regulations on various relevant aspects. The two particularly pertinent to asbestos in soil and made ground are CAR 2012 and CDM 2007.

AimThis chapter is intended to provide an overview of UK legislation and recent case law concerning asbestos, asbestos in soil, worker protection and risk-based land management.



Table 3.1 Main UK law relevant to aspects of asbestos-containing soils (after legislation.gov.uk)

Aspect Relevant legislationCountry

England Wales Scotland Northern Ireland

Prot

ectio

n of

wor

kers

and

gen

eral

pub

lic

Control of Asbestos Regulations 2012

Health & Safety at Work etc. Act 1974

Construction (Design and Management) Regulations 2007

Management of Health and Safety at Work Regulations 1999

Common law of negligence or public nuisance Construction (Design and Management) Regulations (Northern Ireland) 2007

Control of Asbestos Regulations (Northern Ireland) 2012

Health and Safety at Work (Northern Ireland) Order 1978 Management of Health and Safety at Work Regulations (Northern Ireland) 2000

Who

is li

able

for r

emed

iatio

n co

sts?

Part 2A of the Environmental Protection Act 1990 Environmental Damage (Prevention and Remediation) Regulations 2009 (as amended)

Those who are found liable in law for such costs either in breach of contract or under the common laws of negligence or public nuisance

Part III of the Waste and Contaminated Land (Northern Ireland) Order 1997 (not yet enacted)

The Environmental Liability (Prevention and Remediation) Regulations (Northern Ireland) 2009

Part IIA of the Environmental Protection Act 1990

The Environmental Liability (Scotland) Regulations 2009 Environmental Damage (Prevention and Remediation) Regulations 2009

Who

is

liabl

e fo

r co

mpe

nsat

ing

mes

othe

liom

a vi

ctim

s?

Those found liable under common laws of negligence or public nuisance or breach of statutory duty

The Compensation Act 2006 provides that any liability for damages arising whether statutory or at common law is joint and several.

Site

inve

stig

atio

n ac

tiviti

es

In addition to all those applying to protection of workers and the general public:

Construction (Design and Management) Regulations, 2007

Construction (Design and Management) Regulations (Northern Ireland) 2007

Those found liable in law for such costs either in breach of contract or under the common laws of negligence or public nuisance

Dis

posa

l of A

CSS

and

othe

r as

best

os w

aste

s

In addition to all those applying to protection of workers and the general public:

Hazardous Waste (England and Wales) 2005 and Hazardous Waste (Wales) Regulations 2005 and subsequent amendments (there have been several)

Control of Asbestos Regulations 2012

Control of Asbestos Regulations (Northern Ireland) 2012

The Hazardous Waste Regulations (Northern Ireland) 2005 and subsequent amendments (there have been several)

Regulations relating to the definition transfer and disposal of wastes by Approved Asbestos Contractors


CIRIA, C73320

Doe

s th

e la

nd c

onta

inin

g as

best

os re

quire

rem

edia

tion?

Environmental Damage (Prevention & Remediation) Regulations 2009 (as amended)

Part 2A of the Environmental Protection Act 1990 The Environmental Permitting (England and Wales) Regulations 2010

Town and Country Planning Acts

Common law of nuisance and negligence

Planning (Northern Ireland) Order 1991 Pollution Prevention and Control Regulations (NI) 2003 (as amended)

The Environmental Liability (Prevention and Remediation) Regulations (Northern Ireland) 2009

Waste Management Licensing Regulations (Northern Ireland) 2003 (as amended)

Environmental Liability (Scotland) Regulations 2009 (as amended)

Part IIA of the Environmental Protection Act 1990

Town and Country Planning (Scotland) Acts Environmental Damage (Prevention and Remediation) Regulations 2009

Note

The practice used by the UK Government to denote the geographical coverage of an Act of Parliament has been adopted in this table.

3.1.1 ControlofAsbestosRegulations2012(CAR2012)This section briefly highlights key points in CAR 2012 in relation to asbestos-containing land (Table 3.2). Readers should consult the relevant ACOP (HSE, 2013) for a full understanding of its requirements. The ACOP for CAR 2012 (HSE 2013) was published after the preparation of this guide, while the ACOP relating to CAR 2006 (HSE, 2008) was primarily referred to in the preparation of this guide.

CAR 2012 and CAR (Northern Ireland) 2012 set out several important duties that are likely to be relevant where land contains more than ‘trace’ asbestos content.

CAR apply to ‘premises’, which legally include both buildings and the land surrounding them. They also apply to work places in general including work outdoors and would be relevant to any work activity conducted on asbestos-containing land. Consequently, CAR is relevant to works at any site with ACSs (including walkovers, site investigations and remediation). CAR also apply to employers at commercial or industrial premises built on sites with ACSs. However, CAR is unlikely to be applicable to the protection of residents in properties built on such sites. The protection of such residents should be ensured through the planning and Part 2A contaminated land regimes.

CAR places many duties on the ‘employer’ with respect to employees and extends those duties, so far as is reasonably practicable, to other persons who may be affected by the work activity. This includes subcontractors, members of public and residents ‘adjacent’ to development sites during re-development works. Failure to pass on important information to sub-contractors in order to prevent their exposure to asbestos has been found to be a consequence of poor planning (HSE, 2012d).

CAR sets control limits (0.1 f/ml over four hours and 0.6 f/ml over 10 minutes) and a clearance indicator threshold (<0.01 f/ml) for the concentration of asbestos in air associated with work activities. However, employers are required to reduce exposures to asbestos to the lowest level reasonably practicable below the control limit. No limits are set with respect to concentrations in soils.

Table 3.1 Main UK law relevant to aspects of asbestos-containing soils (after legislation.gov.uk) (contd)



CAR requires that the known presence of asbestos at a ‘premises’ be recorded in an ‘asbestos register’, which is an important part of the asbestos management plan. Although not explicitly referred to by the HSE, this could include the known presence of asbestos in soil (discussed further in Section 15.7). It is also arguable that the presumption of asbestos where full inspection had not been possible, which applies under CAR, should also apply to the presence of asbestos in soil (see Regulation 5, Table 3.2).

Table 3.2 Commentary on selected parts of Control of Asbestos Regulations 2012

Regulation Scope

Part 1 Preliminary

1 CAR came into effect on 6 April 2012.

2

CAR defines asbestos as the fibrous silicate minerals as listed in Section 2.1 and the control limit as 0.1 fibres per cubic centimetre of air averaged over a continuous period of 4 hours. This limit is much higher than the background levels of asbestos discussed in Chapter 6. So, compliance with the control limit does not necessarily mean that adequate control of environmental pollution has been achieved. (Compliance with the control limit does not even mean that adequate control of workplace exposure has been achieved. Workplace exposure should be kept as low as reasonably practicable.) Monitoring to detect lower concentrations is needed to ensure developments are ‘safe’ under the planning system, but that is not addressed by CAR.

3

Defines the scope for notification under the Regulations and the key section is the following from Regulation 3:“(2) Regulations 9 (notification of work with asbestos), 18(1)(a) (designated areas) and 22 (health records

and medical surveillance) do not apply where:(a) the exposure to asbestos of employees is sporadic and of low intensity; and(b) it is clear from the risk assessment that the exposure to asbestos of any employee will not exceed the

control limit; and (c) the work involves:

(i) short, non-continuous maintenance activities in which only non-friable materials are handled, or(ii) removal without deterioration of non-degraded materials in which the asbestos fibres are firmly

linked in a matrix, or(iii) encapsulation or sealing of asbestos-containing materials which are in good condition, or(iv) air monitoring and control, and the collection and analysis of samples to ascertain whether a

specific material contains asbestos”.Conditions (a), (b) and (c) all have to hold if the duties on notification, designated areas, health records and medical surveillance do not apply. The types of work mentioned within paragraph (c) are alternatives. The definition of what would be covered by non-friable materials (para. (c) (i) may need to be considered in relation to the condition of ACMs found in the land. For example, asbestos cement would normally be considered a non-friable material but historically crushed asbestos cement (where there are fragments and dust from the asbestos cement) is in a condition such that fibres would be easily released and therefore would appear to be a friable material.The conditions in Regulation 3(2) (a), (b) and (c) have changed between CAR 2006 and CAR 2012. The wording is substantially more stringent in limiting the types of work activity that would meet the exemption. For example, paragraph (c)(ii) refers to “removal without deterioration of non-degraded materials” whereas the 2006 version did not mention ‘non-degraded’. It would be necessary to consider whether materials that have lain in soils would remain ‘non-degraded’. As degradation might depend on various factors (the type of ACM, the soil conditions and site activities), decisions may need to be site specific. However, AIB, lagging and loose insulation will almost certainly be defined as ‘degraded’ after years in the soil. Regulations 9, 18(1)(a) and 22 are likely to [continue to] apply to remediation of land containing large amounts of these materials (eg where the asbestos is driving the need for remediation or influencing how the remediation is being carried out). For strongly bound materials such as asbestos cement and bitumen, the extent of any degradation may be most readily demonstrated by the condition of materials found in the land.The CAR requirements make it quite likely that work undertaken to deal with ACSs may not be exempt under Regulation 3, particularly if it contains friable ACMs such as AIB, lagging and loose insulation.

Part 2 General requirements

4

Sets out several requirements on a duty holder (essentially anyone who has some control or say in what happens on that land) to ensure that exposure of workers and the public to asbestos is prevented. The essence of the requirements is that “in order to manage the risk from asbestos in non-domestic premises, the duty holder must ensure that a suitable and sufficient assessment is carried out as to whether asbestos is or is liable to be present in the premises.”The HSE does not believe the requirements under Regulation 4 were written with anything other than buildings in mind. If it is known that asbestos is present or there is a strong suspicion (eg it is the site of a former asbestos manufacturing activity, demolition of commercial and industrial buildings between, for example, 1940 and sometime around 2000, visual evidence of ACMs in the ground or asbestos being found during screening before analysis of other possible contaminants) then there could be grounds for owners surveying their land for the presence of asbestos.


CIRIA, C73322

4

Regulations 4, 5, 6, 7 and 10 will all apply to site investigation; redevelopment and remediation work on sites containing asbestos. If asbestos is identified as being present in soil, then there needs to be an adequate written plan to ensure that measures are taken to control the risks from that asbestos. A sufficient and suitable plan should be included in all site investigation plans where the former land use suggests asbestos may be present.

5

Requires that before undertaking works (which might disturb asbestos, if present), an employer:(a) “must … have carried out a suitable and sufficient assessment as to whether asbestos, what type of

asbestos, contained in what material and in what condition is present or is liable to be present in those premises; or

(b) if there is doubt as to whether asbestos is present in those premises, that employer:(i) assumes that asbestos is present, and that it is not chrysotile alone(ii) observes the applicable provisions of these Regulations.”

The presumption should apply that in terms of site investigation, where there is demolition or other construction-related material (eg recycled in-fill or fly-tipping), there is likely to be “a doubt as to whether asbestos is present” unless there is reliable information to the contrary.In order to avoid disproportionate responses to this regulation, any brownfield site development could have a contingency plan saying what to do if suspicious material is found (whether asbestos, arsenic, aniline, unexploded ordnance or indeed any other hazardous material). Any asbestos encountered would then be dealt with under CAR.

6

Requires that an employer “must not carry out work which is liable to expose employees of that employer to asbestos unless that employer has:(a) made a suitable and sufficient assessment of the risk created by that exposure to the health of those

employees and of the steps that need to be taken to meet the requirements of these Regulations;(b) recorded the significant findings of that risk assessment as soon as is practicable after the risk

assessment is made; and (c) implemented the steps referred to in sub-paragraph (a).”There are further requirements regarding obtaining information to support a risk assessment, keeping records of such risk assessments and updating the assessments. The legal liabilities for consultants and subcontractors associated with exposing workers to asbestos, mean that it is essential that suitable and sufficient health and safety documentation (including method statements and risk assessments) is prepared, particularly if ACS may be present.

7

Regulation 7(1) requires that: “An employer must not undertake any work with asbestos without having prepared a suitable written plan of work detailing how that work is to be carried out.” The regulation specifies what must be in the plan and the need to work in accordance with the plan and record any subsequent changes to the plan.Work that is more than very minimal, ie as described in exemptions set out Regulation 3(2), will need to be notified in advance to the appropriate enforcing authority (HSE or HSE NI). CAR extended the requirement for notification beyond licensed works (ie notifiable non-licensed work).

9

Sets out requirements that apply to licensed asbestos contractors. The definition of licensed work changed from the 2006 regulations, but the overall meaning appears essentially the same. The preliminaries to CAR specify that ‘licensable work with asbestos’ is “work:(a) where the exposure to asbestos of employees is not sporadic and of low intensity; or(b) in relation to which the risk assessment cannot clearly demonstrate that the control limit will not be

exceeded; or(c) on asbestos coating; or(d) on asbestos insulating board or asbestos insulation for which the risk assessment

(i) demonstrates that the work is not sporadic and of low intensity, or(ii) cannot clearly demonstrate that the control limit will not be exceeded, or(iii) demonstrates that the work is not short duration work.”

10

Requires every employer to ensure that the employer gives any employee [appropriate and] adequate information, instruction and training where that employee:(a) is or is liable to be exposed to asbestos, or if that employee supervises such employees; and(b) carries out work in connection with the employer’s duties under CAR, so that the employee can carry out

that work effectively.

Table 3.2 Commentary on selected parts of Control of Asbestos Regulations 2012 (contd)



11

Sets out a duty on employers to prevent exposure to asbestos so far as is reasonably practicable and in any case minimise any exposure to asbestos and use respiratory protection (for employees) in addition to control exposure. Where exposure is likely to exceed the control limit, the respiratory protection must provide sufficient protection to reduce the actual received exposure to below the control limit and should minimise the exposure as far as reasonably practicable.The duty on exposure extends (beyond employees) to preventing exposure arising from a work activity to anyone (but does not extend to residents/occupants once development has been completed).

15

Covers the arrangements to deal with accidents, incidents and emergencies. Where an unplanned release of asbestos tales place, employers must ensure that immediate steps are taken to:(a) mitigate the effects of the event, restore the situation to normal, and inform any person who may be

affected; and(b) ensure that only those responsible for carrying out repairs and other necessary work are permitted in

the affected area and are provided with: appropriate respiratory protective equipment and protective clothing, and any necessary specialised safety equipment and plant, which must be used until the situation is restored to normal.

16

An important duty that will affect any land that contains asbestos is the duty to prevent or reduce the spread of asbestos: “Every employer must prevent or, where this is not reasonably practicable, reduce to the lowest level reasonably practicable the spread of asbestos from any place where work under the employer’s control is carried out.” These will cover spread in the air and inadvertent tracking of asbestos within and out of the site. Suitable working methods must be adopted and enforced.There are further duties that define requirements for air monitoring, standards to be observed in air testing and site clearance certification, health records and medical surveillance. These will affect the undertaking of work on land containing asbestos.

17 Relates to the cleanliness of premises. There is often temporary accommodation on contaminated land sites. The CAR risk assessment should determine whether clean areas are required etc.

22 Regulation 22 provides for different requirements for medicals and health surveillance depending on whether the work is “licensable work with asbestos” or not.

Part 3 Prohibitions and related provisions

27

There is a requirement under Regulation 27 that any products containing asbestos (supplied under exemptions) must be labelled as containing asbestos. This appears to imply that any recycled soil products that contain asbestos may need to be labelled accordingly or at least labelled that no asbestos was detected above the relevant reporting limit.

3.1.2 Construction(DesignandManagement)Regulations2007(CDM)The Construction (Design and Management) Regulations 2007 (CDM) are intended to improve health and safety in the construction industry. Most projects considering asbestos in soil or made ground will be part of a construction project and fall under the remit of CDM.

It is arguable that site investigations to inform a soil risk assessment under Part 2A are not part of a construction project and therefore fall outside the CDM Regulations. However, the principles are still valid and ought to be considered and applied in the majority of cases where the history of the site suggests that asbestos is present. Site investigations to inform the remediation design even under Part 2A would be part of a construction project (the remediation) and so CDM would apply.

CDM 2007 places legal duties on almost everyone involved in construction work. Those with legal duties are commonly known as ‘duty holders’:

�� clients (including landowners and developers)

�� CDM co-ordinators

�� designers

�� principal contractors

�� contractors

�� workers.

Generic advice on CDM is provided by the HSE (see Useful websites). Practical advice is also contained in the relevant ACOP.

Table 3.2 Commentary on selected parts of Control of Asbestos Regulations 2012 (contd)


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3 .1 .3 The Reporting of Injuries, Diseases and Dangerous OccurrencesRegulations2013(RIDDOR)

Mesothelioma and lung cancer are ‘reportable diseases’ under the provisions of the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR) 2013.

The HSE advises that exposure to asbestos is reportable under RIDDOR when “a work activity causes the accidental release or escape of asbestos fibres into the air in a quantity sufficient to cause damage to the health of any person” (see Useful websites). It is possible that activities involving ACS could cause such a release if they are conducted without suitable controls, or the controls fail. Such events would be classed as a ‘dangerous occurrence’ under RIDDOR and should be reported. If a dangerous occurrence relating to asbestos has been reported, the asbestos management plan or working practices should be reviewed.

3.2 the COmmOn lAW Of neGlIGenCe And nuISAnCe (InCludInG the COmpenSAtIOn ACt 2006)

The UK common law is a set of principles of law that have grown from court judgments over the years. The law of tort, which includes negligence and nuisance, is an example of this. In contrast to the law of contract, where (except in exceptional circumstances) only those contracted with can receive the benefit of the agreement, the duty of care in tort is owed to all those who might be affected by any acts or omissions.

For example, employers have a common law duty of care to the general public and, in addition to their statutory duties, to their staff. If they are negligent then they can be liable for compensating those whom they have injured or damaged. This includes those who have contracted asbestos-related diseases.

The investigations into common law cases begin with the facts: what happened, when, where, to whom and by whom, from the available evidence, both documentary and orally from witnesses. Then the judge makes findings of facts from the evidence presented. The findings of facts are not generally capable of challenge on appeal so it is vitally important that all documents are retained to show clearly what was done.

In asbestos-related disease, there is usually a time interval of decades after the exposure and before the onset of the disease. This often means that the case investigations can run into evidential difficulties, eg memories and documents are lost or imprecise. However, the judge can decide as findings of fact matters that may be in doubt.

To the facts, the judge then applies the relevant statutes and legal case precedents and arrives at a judgement. The more relevant the case precedents to that being tried, and the higher the court that heard the case precedents, the more weight it carries.

The judgements are public documents and the more important ones are published. The British and Irish Legal Information Institute is an easy way to find the rulings (see Useful websites).

The claimant has to prove each of four aspects of their case to succeed:

1 That the defendant owed him a duty of care at the time of the negligent act or omission.

2 That there was a breach of that duty by the defendant.

3 That damage or personal injury has been suffered by the claimant.

4 That the damage or personal injury was caused directly by the defendant’s breach.

noteContracting pleural plaques is not currently accepted as sufficient damage in England and Wales.



This is the same for all negligence cases. Liability (issues 1 and 2) has to be proved before the causation (issues 3 and 4) will be considered.

The test for causation in cases of mesothelioma is treated quite differently to that for other diseases or injuries. Ordinarily in common law, the claimant must show that but for the defendant’s tortious conduct they would not have suffered the damage. While mesothelioma is almost exclusively caused by asbestos exposure, it is not possible for a claimant to prove the ‘but for’ test here because there is not enough scientific knowledge as to which of a number of likely exposures was the specific cause of the mesothelioma. This had the potential result of some tortious defendants escaping liability for the fatal injuries of the claimant.

The case that addressed this conundrum was Fairchild v Glenhaven Funeral services (BAILII, 2002), which reached the House of Lords [now the Supreme Court]. A number of claimants, former employees, claimed that they had been negligently exposed to asbestos, but they could not show which of their former employer defendants had provided the precise fibres that led to the cell mutations ultimately leading to the cancer. The court held that in these circumstances instead of the claimants failing at the last hurdle of proof, causation, each defendant would be liable for the whole claim, as long as there was a ‘material increase’ in the risk created by the exposure.

The courts cannot be more specific about what quantity ‘material increase’ means. This is because the science has not advanced to that point. Currently, it is known that mesothelioma is almost exclusively caused by asbestos exposure and it is thought that there is no minimum exposure to asbestos to avoid illness. The phrase currently means an exposure more than background exposure, which the defendant has caused by their negligence. The test may well change in the future as science advances.

A later House of Lords case sought to water down this outcome by allowing defendants to apportion by reference to relative contribution to risk. Parliament intervened to pass the Compensation Act 2006, which applies in England and Wales, in Scotland (with some changes in terminology) and (with certain exclusions) in Northern Ireland. Where liability arises at common law or under statute, it makes each and every defendant in any mesothelioma claim specifically jointly and severally liable for the losses. Where there is more than one defendant they can apportion the damages between them, either equally or by reference to factors such as intensity and duration of exposure and fibre type. However, even if they claim that others were liable, they have to bear all the claimant’s losses and then take out separate proceedings to recover those contributions from the other defendants.

The Compensation Act 2006 does not really supplant the ‘but for’ test of causation either because section 3 only applies once a defendant is liable (ie once breach is proved, and once causation is proved on a material increase in risk basis). The basis for the ‘material increase in risk test’, which is what supplants ‘but for’ as a test, is case law Fairchild v Glenhaven Funeral Services. So, in effect, the Compensation Act 2006 affects neither the breach nor the causation analysis – liability is already established by the time Section 3 is considered. The Act states that you cannot apportion (ie you cannot just pay your aliquot share) once you are liable at common law or in breach of some other statutory provision, you are liable for the lot.

But what is negligent exposure? The following sections describe a number of cases where this question has been considered.

noteSection 3 of the Act deals with damages relating to mesothelioma.

So, where a ‘responsible person’, ie the defendant, has negligently or in breach of statutory duty caused or permitted ‘another person’, ie the claimant, to be exposed to asbestos so as to have contracted mesothelioma, then the defendant becomes liable for that exposure in the law of Tort, and will be liable to pay the whole of the claimant’s losses, even if the claimant was also exposed negligently on other occasions by other people.


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3.2.1 SienkiewiczvGreif(UK)LimitedandKnowsleyMetropolitanBorough Council v Willmore, [2011, UKSC 10]

The Supreme Court heard both cases together and gave one combined judgement, as is often done when the issues raised by more than one case are so similar that they would be best heard together (Box 3.1).

Box 3.1 Sienkiewicz v Greif (UK) Limited and Knowsley Metropolitan Borough Council v Willmore, [2011, UKSC 10]

The case indicated that Courts would be expected to assess what would constitute a ‘material contribution’ on a case-by-case basis. As indicated by Lord Philips in Box 3.1, a responsibility for even a small proportion of an overall exposure may be considered material, and the indications from the higher courts are that anything that is ‘more than minimal’ in the sense of elevating the exposure above background levels will suffice.

3.2.2 WilliamsvBirminghamUniversity[2011](EWCACiv1242)A subsequent case in the Court of Appeal, the Williams case (Box 3.2), led to a judgment that accepted that a defendant who had followed the standard of conduct of that time would not be regarded as being in breach of duty and hence not liable. This is a ‘breach of duty’ case.

The Court of Appeal also endorsed that any claimant must first establish negligence or a breach of duty as a matter of common law before joint and several liability under the Compensation Act 2006 becomes an issue.

For the person responsible in law for the asbestos-containing land, and for those on site who otherwise have a level of control over exposure risks, the prospect of civil litigation potentially arising at some time in the future from a very small contribution to the asbestos exposure of someone who subsequently develops mesothelioma should not be overlooked. It is important to keep all records in order to show a judge the work that has been carried out and to present the facts accurately.

In Sienkiewicz v Greif (UK) Limited, Enid Costello worked between 1966 and 1984 in an office in a factory that made steel drums, and which released asbestos as part of the process. She had a light environmental exposure to asbestos as she moved about the factory and in the area where she lived. Her daughter brought the claim after her death.

In Willmore v Knowsley MBC, the husband of the deceased, Dianne Willmore, claimed that she had been exposed to asbestos when work was being carried out at her secondary school run by the council including:

�� work to corridor ceiling tiles (over a few days only)�� completion of the original construction work (not proved in court)�� installation of a suspended ceiling (not proved in court)�� disturbance of ceiling tiles by unruly pupils�� ceiling tiles stored in the girls’ toilets (over a period of two weeks).

The first instance judge in the case of Sienkiewicz v Greif (UK) Limited heard the expert evidence and made a finding of fact that the claimant’s exposure to asbestos had increased her risk of mesothelioma by 4.39 in a million, an increase of 18 per cent from a background risk of 24 in a million. The higher courts did not overturn this calculation, but the decision on liability arising from this exposure was overturned from the defendant’s favour at first instance to the claimant’s favour in both of the higher courts (the Court of Appeal and the Supreme Court).

There was no such detailed calculation in the Willmore case. The first instance judge found that each of the three periods of exposure was more than minimal and was foreseeably hazardous. The council appealed to the Court of Appeal, where it lost and then to the Supreme Court where again it lost.

In his Supreme Court judgement, Lord Phillips, presiding, followed this course. Lord Phillips described (Para 142) this situation in the following way: “Of course, the Fairchild [the ‘but for’ test explained above] exception was created only because of the present state of medical knowledge. If the day ever dawns when medical science can identify which fibre or fibres led to the malignant mutation and the source from which that fibre or those fibres came, then the problem which gave rise to the exception will have ceased to exist. At that point, by leading the appropriate medical evidence, claimants will be able to prove, on the balance of probability, that a particular defendant or particular defendants were responsible. So the Fairchild exception will no longer be needed. But, unless and until that time comes, the rock of uncertainty which prompted the creation of the Fairchild exception [endorsed in the Compensation Act] will remain.”



Box 3.2 Williams v Birmingham University [2011] (EWCA Civ 1242) (cf BAILII, 2011)

3.3 plAnnInG, develOpment COntROl And the envIROnmentAl pROteCtIOn ACt 1990

Both the planning system and Part 2A of the Environmental Protection Act 1990 take a risk-based approach to the management of soil contamination in which the local authority acts as the primary regulator. The criteria for the decisions are, however, very different and for good reasons as explained in the following sections.

3 .3 .1 The planning systemPlanning consent from the relevant local planning authority (LPA) gives approval for a site to be used for the approved purpose for the foreseeable future. Planning is a devolved matter so guidance differs among the four countries (Box 3.3).

Michael Williams had studied physics as an undergraduate at the University of Birmingham and in 1974, his final year at the University, he undertook scientific experiments in a service tunnel under central heating pipes in the ceiling lagged with asbestos.

The University’s defence was that although the claimant had been exposed to asbestos, the extent and the circumstances of the exposure to asbestos were so small as to be irrelevant. The University pleaded that it had not breached any duty of care to Mr Williams and, it claimed, nor was any of the admitted exposure to asbestos causative of his mesothelioma.

After hearing the evidence, the first instance judge found as a fact that

�� the lagging in the tunnel was in a bad condition and that the University should have been aware of this (based on the admission by the University, since there was no direct evidence on the state of the lagging either way)

�� the claimant’s exposure in the tunnel to asbestos fibres, particularly crocidolite fibres was at a level close to or above 0.1 fibres per ml but less than 0.2 fibres/ml (this depended on the first finding)

�� that each period of Mr Williams’ work in the tunnel amounted to between 52 and 78 hours in total.

In applying the law, the judge then concluded that this exposure ‘materially increased’ (the legal test for negligent levels of exposure) the probability of the claimant’s contracting mesothelioma as a result of his exposure to asbestos fibres in the tunnel, which would have contained crocidolite. The judge also concluded that the University knew or ought to have known that the pipe lagging in the tunnel contained asbestos and that low-level exposure, particularly to crocidolite, could cause mesothelioma.

However the Court of Appeal, while accepting the findings of fact as to the level of exposure, found that the judge had misdirected herself as to the legal liability. The standard of conduct to be expected from the University was that relating to 1974 in light of the knowledge about asbestos at that time. So Lord Justice Aikens said that the questions to be asked were

(1) the actual level of exposure to asbestos fibres to which the claimant was exposed(2) what knowledge the University ought to have had in 1974 about the risks posed by that degree of exposure to as-

bestos fibres(3) whether, with that knowledge, it was (or should have been) reasonably foreseeable to the University that, with that

level of exposure, the claimant was likely to be exposed to asbestos-related injury(4) the reasonable steps that the University ought to have taken in the light of the exposure to asbestos fibres to which

the claimant was exposed in fact(5) whether the University negligently failed to take the necessary reasonable steps.The Court found that the University would not have known in 1974 that this level of exposure would have given rise to the risk of contracting mesothelioma (question 3) and so they could have done nothing to eliminate the exposure (question 4). This knowledge was critical to the success of the claimant’s claim, so the claim failed at the appeal stage.

Key to the analysis is the official guidance issued by Government Agencies at the time (1974). Guidance Note TDN13 provided a ‘no prosecution’ indication at levels of 2.0 f/ml for white and brown fibres and 0.2 f/ml for blue asbestos. From 1976, when guidance note EH10 was issued, the advice was to reduce exposures to levels as far as reasonably practicable below the TDN13 limits, which would potentially make a “Williams argument” more problematic. The exposure standards, or TLVs (threshold limit values) have of course been reduced further since that time in any event such that running a breach of duty argument in, say, 25 years’ time relating to any measurable exposure occurring today would in practice be unrealistic.

Note: the health risks of asbestos exposure are now better known and so for present day exposures, harm is now reasonably foreseeable. Albeit that practices vary and evolve, evidence that good practice and legislative compliance of the time was adhered will assist in any future claims of negligence in demonstrating that reasonable steps were taken.


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Where contamination (including asbestos) is suspected, proposals for ensuring land is suitable for its intended new use must be submitted by developers to the LPA for approval. This may require a desk study, an intrusive investigation, an assessment of risks and, where necessary, a remediation strategy (and subsequent verification report). These are normally assessed on behalf of the LPA by a contaminated land officer or environmental health officer. It is recommended that developers consult the LPA and their advisors early, particularly if ACSs may be an issue. Remediation requirements can be taken into account as the application proceeds, as there are more options for effective management of contamination. Dealing with contamination, especially involving asbestos, is often easier at the initial stages of development rather than after its completion.

It is appropriate that the planning process adopt a more stringent standard for the levels of soil contamination than are relevant under Part 2A. This prevents developments being determined as ‘contaminated land’ in the future when, and if, acceptable exposures to contaminants change. This is particularly relevant to asbestos, as there is a long history of limits of acceptable exposures to asbestos becoming more stringent.

Box 3.3 National planning policy guidance in England, Wales and Scotland

englandThe National Planning Policy Framework for England (CLG, 2012) does not substantially change the requirements that were in the now withdrawn PPS 23 Annex 2 (CLG, 2004). It makes no mention of asbestos but does refer to contamination and natural hazards.

Local plans, developed by local authorities, should “set out environmental criteria, in line with the policies in this Framework, against which planning applications will be assessed so as to ensure that permitted operations do not have unacceptable adverse impacts on the natural and historic environment or human health, including from … migration of contamination from the site” (CLG, 2012 Para 143).

With respect to the development of individual sites, Para 120 requires that “Where a site is affected by contamination or land stability issues, responsibility for securing a safe development rests with the developer and/or landowner”. Para 121 notes that “Planning policies and decisions should also ensure that … the site is suitable for its new use taking account of ground conditions and land instability, including from natural hazards or former activities such as mining, pollution arising from previous uses and any proposals for mitigation including land remediation or impacts on the natural environment arising from that remediation”. Para 121 goes on to point out that “after remediation, as a minimum, land should not be capable of being determined as contaminated land under Part IIA of the Environmental Protection Act 1990”.

ScotlandPAN 33 (Scottish Executive, 2000) refers to land contamination, and specifically to the ‘suitable for use approach’ (Paragraph 19) as:

(i) ensuring that land is suitable for its current use – in other words identifying land where contamination is causing unacceptable risks to human health and the environment and returning it to a condition where such risks no longer arise

(ii) ensuring that land is made suitable for any new use as planning permission is given for that new use – in other words assessing the potential risks from contamination on the basis of the proposed future use and where neces-sary to avoid unacceptable risks to human health and the environment, remediating the land before the new use commences.

It goes on (Paragraph 75) to state that “it is in the developer’s interests to ensure that development of the site will not result in designation as contaminated land under Part IIA”.

WalesNew Welsh planning policy guidance was published in November 2012 (Welsh Government, 2012). While it makes no specific mention of asbestos, it does require local planning authorities to consider the level of contamination in deciding which sites to allocate for housing in their development plans (Para 9.2.9). In addition it is up to the developer to ensure that the land is suitable for the development proposed (Para 13.5.1) and to carry out “a specialist investigation and assessment” (Para 13.7.1). LPAs however are advised that “development plans should indicate the general location of known areas of contamination and may also include specific proposals for sites known to be contaminated or where the site history suggests a risk of contamination or the land is designated as contaminated land under Part IIA” (Para 13.6.2).



3 .3 .2 Part 2A of the Environmental Protection Act 1990Section 78A(2) of the Environmental Protection Act 1990 states that ‘contaminated land’ is “any land which appears to the local authority in whose area it is situated to be in such a condition, by reason of substances in, on or under the land that – (a) significant harm is being caused or there is a significant possibility of such harm being caused; or (b) significant pollution of controlled waters is being caused, or there is a significant possibility of such pollution being caused”.

The local authority is the primary regulator under the regime and its responsibilities include the identification, investigation and assessment of land. Over the last decade, many Part 2A investigations have focused on, or included, a consideration of asbestos in soil.

Asbestos can, and does, lead to harm to human health that is ‘significant’. Where a population has been exposed to ACSs for many years, it is possible that those exposures caused or contributed to diseases that have already occurred but not been linked with the contamination at that site. This is because the claimant first looks to any potential occupational exposure as the cause of the problem. However, this can mask cases of environmental exposure.

It should be noted that, although the application of Part 2A at sites affected by asbestos might reduce the exposure of prescribed receptors to a low level (ie no longer a “significant possibility of significant harm”), it is not its purpose to remove risk entirely. So, duties under common law may not be met merely by complying with a Part 2A remediation notice.

The regulations and statutory guidance underpinning Part 2A is different in England, Scotland and Wales.

England and WalesThe statutory guidance for England (Defra, 2012a) and for Wales (Welsh Government, 2012) defines the ’significant possibility of significant harm’ to human health in terms of four categories. Categories 1 and 2 meet the definition of contaminated land. Category 3 may include “land where the risks are not low, but … intervention is not warranted” while Category 4 is land where there is no risk or that the level of risk is insignificant or low. These categories are discussed in terms of asbestos in soil in Table 14.4.

ScotlandThe statutory guidance for Scotland (Scottish Executive, 2006) refers to “unacceptable intake” in the discussion on ‘significant possibility of significant harm’. Scottish Government is currently reviewing this guidance and is expected to consult on a new version in the near future. There is no indication whether a similar site categorisation system to that in England will be introduced or not.

3.4 envIROnmentAl dAmAGe (pReventIOn And RemedIAtIOn) ReGulAtIOnS 2009

The European Environmental Liability Directive (Directive 2004/35/CE) imposes obligations and liability on operators of certain activities for ‘environmental damage’. The Directive has been implemented throughout the UK but separate statutory instruments exist for England, Wales, Scotland and Northern Ireland (Table 3.1).

Liability only applies to damage that took place after the inception date:

�� in England, the Environmental Damage (Prevention and Remediation) Regulations 2009 came into force on 1 March 2009

noteScotland has retained the designation ‘Part IIA’ whereas Part 2A has been generally adopted in England and Wales. This is an important legal distinction but in the remainder of this guide references to Part 2A include Part IIA in Scotland.


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�� the Environmental Damage (Prevention and Remediation) (Wales) Regulations 2009 came into force on 6 May 2009

�� the Environmental Liability (Scotland) Regulations 2009 came into force on 24 June 2009

�� the Environmental Liability (Prevention and Remediation) Regulations (Northern Ireland) 2009 came into force on 24 July 2009.

The following discussions are based on the provisions presented in the Environmental Damage (Prevention and Remediation) Regulations 2009 (EDR) for England and relevant guidance (Defra, 2009).

3 .4 .1 Summary of regulationsEnvironmental damage is defined as damage to (a) protected species or natural habitats, or a site of special scientific interest, (b) surface water or groundwater, or (c) land if there is “a significant risk of adverse effects to human health” (EDR 2009 Regulation 4).

For EDR 2009 to apply there needs to be a relevant case where there is an imminent threat of damage or reasonable grounds to believe that there is environmental damage. The operator of the activity (defined as the person(s) who control the activity and so can extend beyond site owners to contractors or third parties) is then under a statutory duty to notify the enforcing authority (either the local authority, environmental protection agency or other agency). The operator is then also under a duty to take steps to limit or prevent further damage.

EDR 2009 apply to certain defined activities. The most pertinent when considering ACSs are:

�� activities regulated under the Environmental Permitting Regulations 2010

�� the transport of dangerous goods.

The enforcing authority has a mandatory obligation to establish whether damage is ‘environmental damage’ under EDR 2009. If so, and if voluntary remediation by the operator is not proposed or accepted, the enforcing authority has a duty to serve a remediation notice or at its discretion can elect to undertake remediation and recover the costs from the operator. It is an offence to fail to report a case or comply with a remediation notice.

Regulation 7(1) states that the EDR are without prejudice to any other legislation relating to damage to the environment, ie in some cases, either the EDR or another environmental regime will apply, and in some cases both regimes may apply. Where there is an imminent threat of damage, the EDR always apply.

Defra (2009 Annex 4) gives some guidance on the interface between the environmental liability regime and other regimes for remediation. In the case of contaminated land, the regimes will be applied in the following order:

�� environmental liability regime

�� planning regime

�� contaminated land regime under Part 2A of the Environmental Protection Act (EPA) 1990.

As well as requiring the remediation of environmental damage of land, EDR also allows pre-emptive notices detailing preventative measures to be served on an operator. It is an offence to fail to comply with such a notice.

Regulation 29 also gives scope for “requests for action by interested parties” requiring the enforcing authority to take action. Given the public perception of asbestos, the potential influence accessible via the EDR may make this the legal mechanism of choice for local campaigners to ensure adequate controls on remediation projects involving ACSs.



Liability is ‘ joint and several’, if multiple parties are involved, and enforcement action can be taken against companies and/or individual managers or staff who gave consent or are proven to be negligent.

There has been little use of this legislation to date (under 10 incidents in each of years 2009 and 2010), and the EDR are intended to be renewed in 2014. As the EDR give substantial powers to enforcing authorities, its interpretation will need to be clarified by future case law from the appeals process.

3.4.2 Applicabilitytoasbestos-containingsoilThe regulations and guidance make no specific reference to asbestos. However, asbestos has the potential to cause environmental damage to land.

It is important to note that diffuse pollution (ie pollution that cannot easily be traced back to a single or definitive source) is excluded from the Regulations unless it is possible to establish a causal link between the damage and the specific activity. This is particularly significant to ACSs, as a causal link may be proven where damage to land could be as a result of emissions of migratory airborne asbestos fibres.

Any operations on asbestos-contaminated land need to be properly planned to ensure that works do not cause further or wider asbestos contamination that may be deemed ‘environmental damage’ under the regulations.

There are exemptions from liability under the EDR that might cover some asbestos-contaminated land such as:

�� historic activities (demolition and dumping etc) that ceased before the inception date of the regulations

�� damage that occurs after this inception date if it arises from a historic incident or event

�� damage from an incident or event after inception if the activity causing it took place, started and finished before the event.

On this basis the ‘old’ activities, which may be responsible for the actual presence of asbestos in soil, may not be covered. However, ‘new’ activities involving historic contamination that then results in environmental damage could fall under the regulations. For example, demolition and remediation works under an environmental permit may include the movement of ACSs and could cause ‘damage’.

3.5 WASte leGISlAtIOnSection 34 of the EPA 1990 imposes a duty of care on persons concerned with ‘controlled waste’. The duty applies to anyone who produces, imports, carries, keeps, treats or disposes of controlled waste. The duty is intended to ensure that waste is managed properly and recovered or disposed of safely.

Waste legislation is complex, as is defining what is a ‘controlled waste’ for the purpose of fulfilling obligations because there is no single factor that can be used to determine if something is a waste or when it ceases to be waste (Defra, 2012b). It is beyond the scope of this guide to detail the extensive legislation with which those licensed to work with, transport and dispose of asbestos have to comply. The following summary is intended as a brief guide to raise awareness of the legislation that may affect a person’s ability to comply with their waste duty of care. It is not exhaustive and should not be relied on to demonstrate compliance. Detailed consideration of the legislation should be taken on a case-by-case basis. Health and safety legislation should also be adhered to for asbestos-contaminated waste soils. Significant amounts of guidance are available on these issues.

Soils and made ground, whether affected by contamination or not, may become waste once they have been excavated. Waste producers (ie anyone whose activities produce waste) are solely responsible for the care of their waste while they hold it.


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Earthworks during construction or remediation phases of a development that involve the movement of ACSs may also fall within the remit of waste legislation. For example, where ACSs are to be reused at depth or under hard surfacing or where foundations are to be excavated in ACSs. Great care should be taken in seeking regulatory approval for such activities.

Soils and made ground that fall within the remit of the Definition of Waste: Development Industry code of practice (CL:AIRE, 2011), are not regarded as waste and are not regulated as such. Although the code of practice makes no specific reference to asbestos, its principles apply to ACSs as to other forms of contaminated soil in England and Wales. In particular, it may be relevant to the reuse of ACSs at the site of origin – the export of ACSs for use at ‘receiver’ sites is unlikely to be acceptable. Any such reuse of ACSs would need to be fully documented in the materials management plan and verification report.

Waste soil can be left at premises but someone needs to be the owner of the waste and take on the duty of care for it. To avoid having the duty inferred, clear agreement should be reached between the parties on a site as to who is responsible for the waste soils. Care and diligence should be exercised when looking at both storage and disposal. If waste is stored on-site then the quantities, method of storage and the duration it is to be held for will need thought as storage may be covered by the EPR 2010. If it is removed off site, the waste soil must be consigned (as evidenced by a waste transfer note or consignment note) to avoid an offence being committed.

There are significant legal restrictions and requirements for the disposal of asbestos waste, such as ACSs. These can have a significant effect on waste disposal costs during both site characterisation works and, particularly, remediation. Costs may arise from:

�� health and safety precautions associated with materials loading and off-site transport (PPE, training, vehicle washdown etc)

�� transport costs (ie an appropriate landfill may not be available locally)

�� packaging and labelling requirement

�� landfill gate prices

�� landfill tax.

Where there are different parties on site, for example contractors, the division of services and the waste produced will need collaborative thought to consider the registration requirements of each party or to ensure that parties do not exceed their permitted quantities and thereby commit an offence.

The producer also has responsibility for ensuring that the descriptions of waste on disposal are accurate and contain all necessary information for safe handling, disposal, treatment or recovery. Using a registered, or exempt, carrier to transport the waste does not necessarily let a producer out of all responsibility for checking the later stages of the disposal of his waste. Checks should be made that the waste carriers and the final destination have appropriate environmental permits to transport and receive the waste, respectively. Waste transfer notes, consignment notes and a copy of the permits should be retained.

In order to reduce disposal costs it is important that potentially asbestos-containing wastes (including soils) are suitably characterised to allow accurate waste classification. Consideration should also be given to the segregation of asbestos-containing wastes from other hazardous and non-hazardous wastes.

The potential cost reductions achievable through treatment methods (see Section 15.3) either to separate ACM (for subsequent disposal) from reusable soils or to lower the waste classification, would need to be investigated on a site-by-site basis.

The requirements of the CAR and The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009 should also be adhered to in respect of the packaging, labelling and transportation of asbestos wastes (see Section 3.8).



3.6 WASte ClASSIfICAtIOnHSE (2012b) notes that “any asbestos product or material that is ready for disposal is defined as asbestos waste” and advises that “if in doubt, always treat waste as ‘hazardous’ or ‘special’”.

The waste classification of ACSs and made ground is not straightforward. Coding and classification of hazardous wastes is described in technical guidance by the Environment Agency (2013). Waste containing asbestos will be hazardous waste if it contains more than 0.1 per cent by weight of asbestos (refers to asbestos and not ACMs), or if it contains less than 0.1 per cent by weight of asbestos but has been deliberately mixed to lower the bulk concentration of asbestos. Mixing hazardous waste with non-hazardous waste is prohibited unless permitted and performed in accordance with an environmental permit. It will also be hazardous waste where any discrete, identifiable fragments of asbestos or ACM (if any fragment contains more than 0.1 per cent asbestos by weight) are present. Guidance is issued by the relevant regulatory bodies in England, Wales, Scotland, and Northern Ireland (for example, Environment Agency, 2013 and SEPA, 2005). Further work on asbestos in soil is being undertaken by the JIWG and may result in changes to that guidance in the future.

Care needs to be taken to ensure that waste ACSs are not mixed with other waste soils during their excavation, storage and handling. In England and Wales, sites producing waste soils that are hazardous may need to register with the Environment Agency (subject to the quantities involved).

Non-hazardous wastes containing asbestos can be disposed of to a suitable non-hazardous landfill authorised to accept low levels of asbestos. Waste soils that are hazardous solely due to the presence of asbestos may be disposed of at a hazardous landfill authorised to receive asbestos, or in a stable non-reactive hazardous waste cell at a non-hazardous landfill authorised to receive asbestos. Waste acceptance criteria (WAC) apply at both classes of landfill and these must be met. If waste soils are hazardous due to the presence of asbestos and other hazardous substances, it may only be disposed of at a hazardous landfill authorised to receive asbestos, subject to achieving WAC for that class of site.

It is important to note that the hazardous waste threshold only applies to the classification of waste and is hazard-based. It is not a level below which risks are acceptable and so it is not an appropriate generic assessment criterion, or remediation target, for ACSs. It is possible for soils containing >0.1 per cent asbestos to safely remain on-site and it is also possible for soils containing much less that 0.1 per cent to pose unacceptable risks.

3.7 ReGIStRAtIOn, evAluAtIOn, AuthORISAtIOn & ReStRICtIOn Of ChemICAlS ReGulAtIOnS 2008 (ReACh)

The EU Directive Registration, Evaluation, Authorisation and restriction of Chemicals Regulations 2008 (REACH) came into force on 1st June 2007 and replaced a number of European Directives and Regulations with a single system. REACH has several aims:

�� to provide a high level of protection of human health and the environment from the use of chemicals

�� to make the people who place chemicals on the market (manufacturers and importers) responsible for understanding and managing the risks associated with their use

�� to allow the free movement of substances on the EU market

�� to enhance innovation in, and competitiveness of, the EU chemicals industry

note‘Hazardous waste’ refers to England, Wales and Northern Ireland, while the analogous term ‘special waste’ has been retained in Scotland


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�� to promote the use of alternative methods for the assessment of the hazardous properties of substances (eg quantitative structure-activity relationships (QSAR)) and read across.

REACH may be relevant in terms of the supply of soils and aggregates that may contain (very low levels of) asbestos. However, NetRegs observed that where wastes are handled but no chemical substances are produced REACH is unlikely to apply. This would appear to be the case for the movement of ACSs.

Annex VI of Regulation (EC) No 1272/2008 states that all forms of asbestos have the following hazard statement codes:

�� H350 – which may cause cancer

�� H372 – which causes damage to organs.

Waste materials from construction and demolition activities are classed as waste according to Directive 2006/12/EC. While a material is classed as waste, it is completely exempted from REACH (it is not even considered to be a substance at this point). REACH can potentially apply when substances are recovered from waste. However, there is derogation from the registration part of REACH for recovered substances that have already been registered by any other supplier.

For inert construction and demolition waste an end-of-waste protocol must be met for it to cease to be waste. Only when this protocol is met does REACH need to be considered. For aggregates that do meet the end-of-waste protocol, the shape of the aggregates is more important to their function than their chemical composition. This means that under REACH, they are treated as articles. Further details on this are given in the REACH guidance on recovered substances (ECHA, 2010). Wastes with significant amounts of asbestos are unlikely to meet the end of waste protocol. Additionally, asbestos normally needs to be removed separately before full demolition so it would seem unlikely that material meeting the protocol would contain asbestos.

The restriction in Annex XVII of REACH applies to placing on the market materials or objects to which asbestos has been intentionally added. So, a material that contains asbestos as an unintended impurity would not be covered by the restriction.

3.8 pACKAGInG And lAbellInGThe United Nations (UN) has established a universal system for the classification, packaging, marking and labelling of dangerous goods to facilitate their safe transport. National and international regulations governing road, rail, sea and air transport are all based on the UN system. Under the regulations, packaging must meet or exceed minimum standards of performance before it can be authorised for the carriage of dangerous goods.

Asbestos-contaminated soil or waste rubble falls within UN 2212 or UN2590, Class 9. Such material should be transported in certified packaging (available in up to 2 tonnes capacity bags) within a skip or freight container (Figures 3.1 and 3.2). The HSE provides guidance on packaging and documentation requirements for carrying asbestos and asbestos waste (see Useful websites).

Packaging for asbestos-containing waste is tested with surrogate materials such as wetted rock wool or sand, plastics pellets and foam. The UK competent authority is the Secretary of State for Transport. The Vehicle Certification Agency (VCA) Dangerous Goods Office (DGO) operates the UN package certification scheme in accordance with the “arrangements for performance testing, certification and marking of packaging for dangerous goods”, on behalf of the Secretary of State. The VCA packaging approvals database contains details of current certified packages (see Useful websites).

The packaging and labelling of soil samples is described in Section 11.2.2.



Figure 3.1 Vehicle placard and warning sign for asbestos

Figure 3.2 UN compliant packaging for asbestos

3.9 CARRIAGe Of dAnGeROuS GOOdS ReGulAtIOnS 2009 (CdG)

CDG 2009 implement the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR). They came into force on 1 July 2009, replacing the 2007 regulations. All asbestos waste is subject to Schedule 2 of CAR 2012. Most waste is subject to CDG 2009. ARCA (2006) is a useful guide, which advises that:

�� firmly bound asbestos, ie asbestos cement and articles with asbestos reinforcement, does not release hazardous or respirable fibres easily and the CDG does not apply

�� CDG 2009 applies for all other asbestos waste

�� there are no special provisions for low concentrations in soil.

The transport of soil samples is described in Section 11.2.20.

Vehicle placard Asbestos warning sign


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With respect to the transport of larger volumes (eg wastes from remediation), the term ‘light provisions’ apply to the transport of up to 1000 kg of chrysotile-containing soil or 333 kg of soil containing any amphibole asbestos:

�� the driver does not have to have received formal training but must demonstrate awareness of the nature of the load

�� a 2 kg dry powder fire extinguisher must be carried

�� the material must be segregated from any others and safely secured

�� there are no requirements for markings.

The full requirements apply to any larger volumes:

�� the driver must hold a certificate for the correct category (there are nine), allowing transport of dangerous goods

�� the correct markings must be displayed, ie hazard placards, and correct fire extinguishers etc carried.

In both scenarios, the material must be in UN certified packing – a sheeted wagon is not sufficient.

Summary

�� CAR 2012 is the most important legislation for protection of workers and general public from asbestos exposures resulting from work activities

�� CAR impose duties on clients as well as consultants and contractors�� CAR and CDM require adequate protection of any workers who may be

exposed to asbestos during the investigation, assessment, management or remediation of ACSs

�� common law liability through negligence could trigger joint and several liability through the provisions of the Compensation Act 2006 for the owners and occupiers of sites affected by asbestos in soils or their advisors

�� soil risk assessments under planning require developers to show the development will be safe and the planning system to ensure that the site is suitable for use

�� soil risk assessments under Part 2A would need to suggest that there is a ‘significant possibility of significant harm’ (SPOSH) to justify determination as ‘contaminated land’

�� however, meeting the objectives of the planning or Part 2A regimes may not be sufficient to avoid liabilities under common law

�� disposal options of ACSs and other asbestos wastes vary with the asbestos content of the waste

�� carriage and labelling restrictions apply to materials containing or suspected of containing asbestos.



4 Asbestos types, uses and products

4.1 typeS Of ASbeStOSAsbestos is a general name given to the needle or fibre shaped forms of several naturally-occurring fibrous silicate minerals.

The Control of Asbestos Regulations 2012 defines asbestos as the following:

“ fibrous silicates:

(a) asbestos actinolite, CAS No 77536-66-4

(b) asbestos grunerite (amosite), CAS No 12172-73-5

(c) asbestos anthophyllite, CAS No 77536-67-5

(d) chrysotile, CAS No 12001-29-5 or CAS No 132207-32-0

(e) crocidolite, CAS No 12001-28-4

(f) asbestos tremolite, CAS No 77536-68-6.”

There are also other asbestiform minerals (eg Richterite and Winchite) that are not legally classed as “asbestos with potential health hazards”. These are unlikely to be encountered and are not specifically considered in this guide. However, if present, it would be advisable to treat them as asbestos.

All asbestiform minerals readily split longitudinally into fibres (HPA, 2007). Asbestos fibres neither dissolve in water nor evaporate, and they are resistant to heat, fire, chemical and biological degradation and are mechanically strong. Due to these properties, asbestos was widely used in many products including insulation material, friction products and fire breaks.

There are two groups of asbestos types: amphibole and serpentine:

�� serpentines: chrysotile is the only asbestiform serpentine mineral. It is a magnesium silicate, often referred to as ‘white asbestos’. Chrysotile fibres are soft, flexible and usually curved. They may be separated easily into small bundles and individual fibrils. Due to their structure they may be woven and can withstand mechanical treatment better than the amphibole fibres. Chrysotile is not resistant to acids but is resistant to attack by alkalis

�� amphiboles: crocidolite (‘blue asbestos’), amosite (‘brown asbestos’), asbestos anthophyllite, asbestos tremolite and asbestos actinolite are all amphiboles. Not all amphibole minerals are asbestiform (fibrous) and the names anthophyllite, actinolite and tremolite can also refer to the non-asbestiform varieties whereas amosite and crocidolite refer explicitly to the asbestiform variety. Fibres have a rod- or needle- shaped appearance. They are more resistant to heat and to attack from acids than chrysotile fibres. All varieties of asbestos are resistant to attack by alkalis.

Chrysotile, amosite and crocidolite were the main asbestos types used commercially. Commercial imports of chrysotile into the UK continued until 1999 whereas amosite and crocidolite imports ended in 1980 and 1972 respectively. In total, about seven million tonnes of asbestos were imported into the UK. About 90 per cent of imports were chrysotile, about 10 per cent amosite and approximately one per cent crocidolite.

AimThis chapter defines what ‘asbestos’ means, the different types of asbestos minerals and the wide range of ACMs that they were used in, and the uses for these materials. It will also summarise the amounts of asbestos imported into the UK in the past.


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4.2 ASbeStOS uSeS And mAteRIAlSAsbestos and ACMs were widely used in buildings. Shuker et al (1997) estimated that asbestos was in 75 per cent of commercial buildings. Watson (2010) estimated that asbestos was present in 2.4 million homes and that it was present in 30 per cent of houses and 60 per cent of flats built between 1965 and 1984.

Informal and formal prohibitions on the types and forms of asbestos in use were progressively applied from 1969 onwards, and amphibole asbestos was rarely used after 1980 and formally prohibited from 1 January 1986. Chrysotile use was also progressively restricted during this period but was only formally prohibited in 1999. So, it is possible that asbestos is present in any building constructed before 2000.

Common uses for asbestos include sprayed coating (eg on steel framework and ceilings for fire protection and as an acoustic absorbent surface), lagging (on boilers, furnaces, pipework), insulating boards (for insulation and general building purposes), asbestos cement (roof sheets, pipes, tiles, preformed cement goods), ropes (for seals and insulation), cloth (fire and heat protection), car brakes and clutches, ceiling and floor tiles, coated metal, textured paints and reinforced plastic among others. HSE (2010) describes a wide range of ACMs, also supported by photographs. Appendix A1 of this guide is taken from HSE (2010). It lists and describes common ACMs in order of their friability (or propensity to release airborne asbestos fibres).

4.3 ASbeStOS-COntAInInG demOlItIOn mAteRIAlS And COnStRuCtIOn WASte

It is not uncommon for small amounts of ACM and/or asbestos fibres to be present in contemporary demolition materials. While it is unlikely that substantial amounts of asbestos contamination will result from responsible contemporary demolition, it can be difficult to remove all asbestos from a building before demolition. Some ACMs (such as Artex or bitumastic materials containing asbestos) may be intentionally left in place, and mistakes do occur.

Fly tipped demolition and construction materials frequently contain asbestos. HSE (2012c) has published guidance on dealing with asbestos in fly tipped materials.

In contrast, uncontrolled demolition of buildings and structures in the past generated a wide variety of heterogeneous waste. Many such wastes are likely to contain ACMs, including cement sheeting, insulating boards, fire protection insulation, thermal insulation and blinding layers, and in some cases free fibres will be present. These wastes may have been mixed into the ground, used to backfill holes, disposed of in basements or the base of structures (such as gas holders) or used as foundation materials for new construction.

The importance of identifying the potential for such demolition wastes during the desk study and walkover to ensure appropriate health and safety provisions are implemented are discussed in Chapter 10.

Summary

�� the term asbestos relates to one of several fibrous minerals regulated under UK law that are known to cause serious health effects when inhaled

�� large amounts of chrysotile and smaller amounts of amosite and crocidolite were imported into the UK in the 20th century

�� ACMs were widely used as construction materials, and it is difficult (often not possible) to ensure that all asbestos is removed before demolition

�� building rubble is liable to contain ACM, and may contain free fibres. Such asbestos can be difficult to detect and may not be visible.



5 Asbestos and health

Inhaling asbestos fibres can cause asbestosis, lung cancer and mesothelioma as well as non-malignant pleural disease. Asbestos fibres that are not in the air cannot be inhaled and do not pose a risk to health until they become airborne (and able to be inhaled). The main asbestos-related diseases are:

�� non-malignant pleural disease

�� asbestosis

�� lung cancer

�� mesothelioma.

5.1 nOn-mAlIGnAnt pleuRAl dISeASeNon-malignant pleural disease is a non-cancerous condition affecting the outer lining of the lung (the pleura). It includes two disabling forms of disease, diffuse pleural thickening and the less serious pleural plaques.

A substantial number of cases continue to occur each year in the UK, mainly due to workplace asbestos exposures many years ago. However, this disease is not considered to be a concern at environmental exposure levels, including those arising from ACSs, and is not discussed further.

5.2 ASbeStOSISAsbestosis is a fibrosis of the lung, and it occurs only after very heavy industrial exposure. However, this disease is not considered to be a concern at environmental exposure levels, including those arising from ACSs and is not discussed further.

5.3 ASbeStOS-RelAted CAnCeRSThe primary diseases of concern at environmental exposure levels are the asbestos-related cancers, which are lung cancers and mesotheliomas. There is no specific data on what contribution ACSs make towards background environmental exposures to asbestos in the UK (Section 6.3). To date no cases of asbestos-related cancer in the UK have been directly linked to exposures from ACSs.

The relationship between exposure to asbestos and the incidence of lung cancers and mesotheliomas has been assessed based on about 20 epidemiological studies of populations exposed in traditional asbestos industries (HEI, 1991, Hodgson and Darnton, 2000, and Berman and Crump, 2008). These studies provide a sound body of evidence demonstrating the link between exposure to asbestos and these diseases. Where ACSs give rise to airborne exposures, developers and landowners could, in the future, be deemed to have contributed to the causation of, and be liable for, any asbestos-related cancers that occur.

There is considerable uncertainty as to whether children are more susceptible to asbestos-related cancers than adults (Section 14.5). However, given the longer life expectancy after exposure, the predicted lifetime risks will be higher for those exposed during childhood than those with similar exposure in adulthood.

The risk of lung cancer and mesothelioma, and the uncertainties in the various models used to predict them, are discussed in more depth in Chapter 14.

AimThis chapter summarises the known health effects of asbestos exposure and indicates the main characteristics of the connections between exposure to asbestos and the risk of these health effects.


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5 .3 .1 Lung cancerGlobally, smoking is the most significant cause of lung cancer (WHO, 2000), but asbestos exposure has also been shown to increase the incidence of several forms of lung cancer, including bronchial carcinoma and adenocarcinoma. In the UK, lung cancer is much more common than mesothelioma but, in the vast majority of cases, is attributable to causes other than asbestos exposure, such as smoking and exposure to natural radon.

The risk of lung cancer increases with cumulative exposure. However there is a latency period (the period after exposure but before disease occurs). This can be as short as five years but is normally more than 20 years (Doll and Peto, 1985).

Asbestos exposure causes approximately the same percentage increase in existing risk for smokers and non-smokers, but since the pre-existing risk is much greater in smokers, most additional lung cancers caused by asbestos occur in smokers.

5 .3 .2 MesotheliomaMesothelioma is a cancer of the lining of the lung (the pleura) or the abdominal cavity (the peritoneum). Mesothelioma is a painful and disabling disease that is inevitably fatal, usually within 18 months of diagnosis of the disease.

The risk of mesothelioma increases with cumulative exposure. The latency period (the period before disease occurs) is usually between 10 and 60 years, with an average of around 40 years. Unlike lung cancer, the risks of mesothelioma are believed to be independent of smoking habits.

It is generally accepted that almost all of these cases of mesothelioma are associated with exposure to asbestos (Peto et al, 1995, Peto et al, 2009). However, due to the historical preponderance of men in the occupations most at risk of asbestos exposure, mesothelioma is currently much less common in females than in males. It is considered that a spontaneous background incidence for all cancers occurs, but for mesothelioma it is estimated that this accounts for only a small percentage of diagnoses (Burdett pers comm).

In the UK, the number of mesothelioma deaths has increased from 153 in 1968 to 2347 in 2010 (HSE, 2012a). The incidence of mesothelioma has followed the pattern of asbestos use within the UK (Figure 5.1). The incidence of mesothelioma rose rapidly about 30 years after the rapid increase of asbestos imports around the early 1960s. Despite the ban on the use of asbestos, mesothelioma deaths were still rising in 2008 (Figure 5.1). Based on the pattern of asbestos imports, HSE (2011) predicted a peak of ~2100 deaths in males in 2016 followed by a rapid decline.

The increasing lag between the time of imports and disease incidence is attributed to the pattern of use of asbestos. Up until the 1970s, exposures predominantly occurred during manufacturing and installation of ACMs. However, the rapid reduction in manufactured ACMs during the 1970s meant that exposures were increasingly due only to the disturbance of ACMs by tradesmen during refurbishment etc. As a result, significant occupational exposures have continued beyond the peak in imports.

Britain currently has the highest rate of mesothelioma per population and this may be related to the historical use of amosite (mainly in AIB) in the UK (Peto et al, 2009). Britain was the world’s largest importer of amosite. The USA, in contrast, used similar amounts of chrysotile and much more crocidolite and has a third to a fifth the mesothelioma rates of Britain (Peto et al, 2009).

There is evidence that the background incidence of mesothelioma in the UK has been rising recently (Rake et al, 2009, and Peto et al, 2009). It currently stands at about 100 to 200 cases per year. Many of these cases may be related to unrecognised exposures or low level environmental exposures. The lack of information on background asbestos concentrations in soils (see Section 6.3.3) and the extent to which such soils release airborne fibres (see Chapter 9), mean that the extent to which ACSs may be contributing to such increases (and whether further increases are likely) is not known.



Figure 5.1 Asbestos imports compared to actual and predicted mesothelioma deaths (after Peto et al, 1995)

More recent estimates (HSE, 2011) predict lower peak death rates.

5 .3 .3 Indications of disease caused by environmental exposuresMost assessments of the incidence of disease that may be caused by environmental exposure to asbestos are based on extrapolation of relationships between exposure and incidence from populations with substantial exposures (for example as described by WHO, 2000). However, the implications of environmental or other low level exposure have also been indicated by a different type of study. Rake et al (2009) conducted telephone interviews with 622 mesothelioma patients (512 men, 110 women) and 1420 population controls. They obtained lifetime and residential histories of exposure to asbestos. They noted that this was the first such population-based study in the UK, and the largest worldwide. They commented, that:

“The cumulative female mesothelioma death-rate by age 70 is now more than three times higher in the UK (0.037%) than in the US (0.012%). If this is due to differences in asbestos exposure, more than two thirds of mesotheliomas in British women born since the 1930s are caused by asbestos, far more than the 38% (Table 6: 42.0/110) that were attributed to identified exposures in our study. A similar conclusion is suggested by the three-fold increase in the death-rate in British women between 1975–1979 and 2000–2004. This would imply that at least 30% of female cases (of the order of 100 per year) are caused either by environmental asbestos exposure or by occasional or ambient exposure in occupational settings that we have classified as low risk. If so, there is presumably a similar number in men. Many apparently spontaneous mesotheliomas are therefore likely to be due to an increase in ambient asbestos exposure that coincided with the widespread occupational exposures of the 1960s and 1970s.”

Incidence of mesothelioma has also been associated with environmental exposures to asbestos in specific areas where land has been contaminated with asbestos in Libby, Montana (see Chapter 10) and in Goor in the Netherlands (Health Council of the Netherlands, 2010).

5.4 fIbRe pOtenCyAnalysis of the various epidemiological studies (HEI, 1991, Hodgson and Darnton, 2000, and Berman and Crump, 2008) clearly shows that there are differences in the cancer-causing power, or potency, of the different asbestos types (ie crocidolite, amosite and chrysotile).

In the case of both lung cancer and mesothelioma, chrysotile is generally accepted as posing lower, but not negligible, risks than amphibole fibres (ie crocidolite and amosite). However, there remains some controversy about the magnitude of the difference in relative potency.

Differences in potency are discussed further in Section 14.4.


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5.5 fIbRe SIzeFibre concentrations are traditionally measured (by the Phase contrast optical microscope method) in terms of concentrations of fibres thinner than 3 µm, aspect ratio greater than 3 to 1, and length greater than 5 µm. (In comparison, a human hair is 40 to 120 microns (µm) in diameter.) This is regarded as an index of fibre concentration rather than being precisely aligned with counting the fibres of sizes considered to pose the greatest risk. The resolution limit of the optical microscopy technique is such that fibres thicker than about 0.2 µm are visible under the phase contrast microscope.

The relationship between fibre size and disease is uncertain but statistical analysis of animal experiments tends to show that the longer (>5 µm) and thinner fibres (<0.15 µm) are likely to be the most carcinogenic. This has implications for the use of Phase Contrast Optical Microscopy (PCOM) in measuring airborne asbestos exposures as the thinner fibres cannot be counted by this method. However, unless the proportion of thin fibres in environmental exposures (eg from ACSs) is greater than in historical occupational exposures, PCOM can still provide valid exposure measurement for estimating risk.

The strengths and weaknesses of PCOM and other methods are discussed in Chapter 12.

5.6 CleARAnCe meChAnISmSOnce inside the lungs, there are several clearance mechanisms that will remove fibres from their site of deposition (WHO, 2000), including:

�� mucociliary clearance

�� translocation within alveolar macrophages

�� uptake by epithelial cells.

These mechanisms usually remove 95 to 98 per cent of deposited fibres, as most of the fibres have lengths less than about 5 µm. Fibres less than 15 µm long are often engulfed by macrophages. Longer fibres are have been shown (eg Berman and Crump, 2008) to have greater health effects possibly because they are more difficult to clear from the lungs.

Asbestos usually occurs as bundles of smaller fibres (fibrils), and the different types and sources of asbestos will have different dimensions but they may be up to several millimetres in length (eg Virtal, 2006). Although both chrysotile and amphibole asbestos are generally insoluble, within the lungs chrysotile fibres can subdivide into the constituent fibrils that will partially dissolve. In contrast, the amphibole asbestos types are less soluble in lung fluids, and so are more durable and have an extended residence time in the lungs (WHO, 2000). Such differences have been suggested as mechanisms to explain the different potencies observed for the different asbestos types.

For example, Berry (1999) used modelling approaches to show that the slow rate of elimination of amphibole fibre, coupled with the faster rate for chrysotile, could be an important factor in explaining the higher rate of mesotheliomas in people exposed to amphibole compared with chrysotile. Based on this work Berry has suggested modifications to the usual power relationship used to model risks by including a term reflecting a gradual elimination of asbestos from the lungs over time (Berry, 1991, Berry, 1993, and Berry, 1995). However, this is a relatively minor correction to the modelled risks.

5.7 WhAt IS An AppROpRIAte bASIS fOR ASSeSSInG ASbeStOS-COntAInInG SOIlS?

It is generally accepted that asbestos is a genotoxic carcinogen, although these is no direct evidence that a genotoxic mode of action is responsible for the observed mesothelioma incidence.



Environment Agency guidance on the toxicological assessment of contaminants in soil (Hosford, 2009), describes differing approaches for contaminants exhibiting threshold and non-threshold toxicity:

�� for threshold toxicity there is “some, non-zero, measurable amount of exposure (dose) that is required before a biological threshold is breached and an adverse effect is produced”

�� non-threshold toxicity relates to contaminants where the mode of action “is such that there is no basis to assume a threshold exists. This is most notably the case for many mutagens and genotoxic carcinogens”.

5.7.1 Thresholdornon-thresholdSome uncertainty exists as to whether or not a “safe” level of airborne asbestos fibre exists below which there is no further increase in risk, but the issue has been analysed and argued in the published literature (Smith and Saunders, 2007, and Hodgson and Darnton 2000).

It is generally accepted that it is impossible to prove the existence of any such threshold based on epidemiological studies. In 2011, HSE’s WATCH sub-committee concluded that:

“… there are risks of asbestos-induced cancer arising from work-related cumulative exposures below 0.1 fibres/ml.years. The risk will be lower, the lower the exposure, but “safe” thresholds are not identifiable. Where potential exposures to amphiboles, particularly crocidolite, are below 0.1 fibres/ml.years (for example, 0.01 fibres/ml.years), the available scientific evidence suggests no basis for complacency, but rather a basis for active risk management” (WATCH, 2011).

In such circumstances the appropriate public health position is to assume that no threshold exists (Smith and Saunders, 2007). Hodgson and Darnton (2000) concluded that any such threshold, if it exists, would be “very low”. However, the existence of a threshold would have significant implications for the assessment of ACSs, as in many circumstances the resulting exposures are likely to be very low.

All current asbestos exposure-risk models (Chapter 14) assume that no threshold exists and that risks continue to diminish as exposures reduce.

5 .7 .2 Carcinogenic mode of actionAs no threshold can be demonstrated, consideration has been given to whether asbestos is or is not a genotoxic carcinogen, as by definition no threshold can exist for the latter. However, it seems unlikely that this line of reasoning will establish if asbestos should be treated as a threshold or non-threshold carcinogen in the near future.

The International Agency for Research on Cancer (IARC) has reconfirmed that asbestos is a human carcinogen, based primarily on epidemiological evidence supported by evidence of carcinogenesis in animals (IARC, 2012).

Many studies have investigated the potential genotoxic or mutagenic action of asbestos but the evidence is equivocal. For example, roughly half the studies reviewed by the ATSDR (2001) were positive for genotoxicity and mutagenicity (ie damage to DNA or chromosomal aberrations). It is generally accepted that asbestos is a genotoxic carcinogen, although these is no direct evidence that a genotoxic mode of action is responsible for the observed mesothelioma incidence (ATSDR, 2001, and 2010).

Although the mechanisms of carcinogenesis are not fully understood, it is generally agreed that physical-chemical properties of the fibres (including fibre dimensions, durability and iron content) are important in determining their potency and that fibres in the lungs initiate a variety of responses leading to inflammation and cell and tissue damage (ATSDR, 2001).

A number of direct and indirect mechanisms have been proposed, and interactions between them may be involved. ATSDR (2001 and 2010) identified three current hypotheses (see Box 5.1).


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Box 5.1 Possible modes of action for asbestos proposed by ATSDR (2001 and 2010)

The HSE (1996) have described a mode of action for asbestos and other fibres analogous to point 3 in Box 5.1, and have restated this relating specifically to asbestos in a report to WATCH Committee (WATCH, 2008).

5 .7 .3 Metric of exposure and thresholds for environmental exposures

Guidance on the selection of appropriate toxicological benchmarks for the assessment of soil contaminants in the UK (Hosford, 2009) points out that for most contaminants assessments can be based on contaminant mass, but for asbestos “it is the number of (appropriately sized) asbestos fibres that determines the risk”. So, for asbestos the appropriate metric of exposure is its concentration in inhaled air (eg f/ml or f/m3).

The Dutch have defined negligible risk (NR) (0.001 f equivalents per ml) and maximum permissible risk (MPR) concentrations of asbestos in air (0.1 f equivalents per ml) for use in assessing risks from environmental exposures (Swartjes and Tromp, 2003, 2008). The definition of fibre equivalents is given in Box 5.2. It should be noted that these negligible risk and MPR are ‘yearly average’ values. Recent recommendations from the Dutch Health Council (2010) have proposed new lower recommended values.

Box 5.2 Definition of fibre equivalents (Swartjes and Tromp, 2003 and 2008)

WHO (2000) published air quality guidelines for a number of substances including asbestos. They concluded that “no safe level can be proposed for asbestos” and that “exposure should therefore be kept as low as possible”. They also presented estimates produced by others that lifetime exposure to 0.0005 f/ml of a population of whom 30 per cent are smokers, would result in lung cancer risks in the order of 10-6–10-5 and mesothelioma risks in the range 10-5–10-4. It was proposed that this may provide adequate health protection, but acknowledged that “their validity is difficult to judge”.

In the UK, no thresholds for environmental exposures to asbestos have been set to protect the UK population from non-occupational exposures and this seems unlikely to change in the foreseeable future. It should be noted that the control limits (0.1 f/ml over four hours and 0.6 f/ml over 10 minutes) and clearance indicator threshold (<0.01 f/ml) set for occupational exposures in the UK under CAR are orders of magnitude higher than the environmental thresholds proposed by WHO. Furthermore, the ACOP for CAR 2012 (HSE, 2013) clearly states that the clearance indicator threshold “should be taken only as a transient indication of site cleanliness … and not as an acceptable, permanent environmental level.” The current control limits are also not appropriate thresholds for the assessment of environmental exposures.

Acceptable and unacceptable environmental exposures are discussed further in Section 14.6.

1 Direct interaction with cellular macromolecules: surface charge on asbestos fibres leads to potential interaction with cellular macromolecules (eg proteins, DNA and RNA) and membranes. Such interactions are believed to result in conformational changes that may impair function. Asbestos has been shown to reduce enzyme function, and chromosome segregation.

2 Generation of reactive oxygen species: the presence of asbestos fibres is believed to result in the formation of hydroxyl radicals etc and associated damage within the cells. Asbestos fibres have been shown to induce lipid per-oxidation, and induce cellular enzymes that mitigate reactive oxygen damage.

3 Othercell-mediatedmechanisms(especiallyinflammation): such mechanisms are not well understood, but it is known that asbestos fibres cause the release of cellular factors that co-ordinate protective responses including inflammation, immune responses, cell proliferation and cell death. Because long asbestos fibres are not effectively eliminated from the lungs, it is suggested that the chronic stimulation of these responses results in carcinogenesis.

Dutch policy defines 1 chrysotile fibre with a length > 5 μm=1 fibre equivalents, chrysotile fibre with a length < 5 μm= 0.1 fibre equivalents; 1 amphibole asbestos fibre with a length > 5 μm= 10 fibre equivalents and 1 amphibole asbestos fibre with a length < 5 μm= 1 fibre equivalents. These definitions are not compatible with UK policy and guidance.



Summary

�� the risk from asbestos is related to the inhalation and retention of airborne fibres in the lungs. The risk increases with cumulative exposure

�� there is a long latency (usually between 10 and 60 years) between exposure to asbestos and the onset of asbestos-related lung cancer or mesothelioma – there are no apparent ill effects at the time of inhalation

�� the fibres that give rise to these disease are very thin, and are not visible to the naked eye. HSE has used the phrase “the invisible killer” to describe the risks from exposure to airborne asbestos fibres. The fibres counted by phase contrast optical microscopy are regarded as an index of exposure and are used to measure the exposure for assessing the risk

�� the epidemiological evidence relating occupational exposure to asbestos and the subsequent occurrence of mesothelioma (and lung cancers) is stronger than for most other potential soil contaminants. Carcinogenicity of asbestos has also been demonstrated in animal studies

�� there are clear differences in carcinogenic potency between the different types of asbestos: crocidolite> amosite> chrysotile. The magnitudes of these differences in the potencies are subject to debate, but it is clear that the differences are real and substantial

�� despite extensive research into the toxicological mechanisms of asbestos, there is still much we do not fully understand about how it causes mesothelioma/lung cancer. Several different mechanisms may be involved.


CIRIA, C73346

6 human exposures to asbestos

6.1 OCCupAtIOnAl expOSuReSThe long history of industrial uses for asbestos has resulted in substantial occupational exposures, most notably during the historical manufacture of asbestos-containing products and, more recently, by tradesmen disturbing ACM during building maintenance work etc.

Occupational exposure to asbestos is reported by the HSE to be “the single greatest cause of work-related deaths in the UK” (see Useful websites). Past practices often involved no protection or inadequate protection for those working directly with asbestos or asbestos-containing products. There are many accounts in the public domain of working conditions that involved substantial exposure to asbestos. In particular, ACMs were widely used in the construction of buildings in the 1960s and 1970s. For example, workers installing asbestos panels into Glasgow’s Red Row Flats in the 1960s were nicknamed the ‘white mice’ because of the coating of asbestos dust on their clothes (Johnson and McIvor, 2000). The consequences are seen in the incidence of asbestos-related disease. National statistics show that nine out of the 20 occupational groups (for males) with the highest incidence (in 2002 to 2005) of asbestos-related mesothelioma were within the construction sector. The four occupational groups at highest risk are in the construction sector (HSE, 2008a). Earlier McElvenny et al (2005) reviewed data from 1968 to 2001 and reported metal plate workers and vehicle body builders as being the highest risk occupations for males.

Increasingly stringent controls on occupational exposures to asbestos have led to significant reductions in such exposures. However, the annual death rate from mesothelioma is still increasing and is expected to continue to rise for a few more years before decreasing as the efforts to prevent exposure bring their benefit.

6.2 pARA-OCCupAtIOnAl expOSuReAsbestos-related deaths have also been reported in the household of occupationally-exposed workers, particularly where work wear was taken into the home. Such exposure of the families of workers is termed ‘para-occupational’ or ‘take-home’ exposure. The levels of exposure are difficult to determine but they may have been substantial in the era when heavily contaminated work clothes were taken into workers’ homes.

In a study of the risks of mesothelioma from occupational, domestic or environmental exposures, Rake et al (2009) commented that “The only substantial risk factor in those with no direct occupational exposure was living with a high-risk worker, a hazard that has been recognised for many years.”

A recent review by Donovan et al (2012) considered literature from around the world, commenting on published ‘household cases’ (ie cases attributed to exposure in the home), and concluded that “the vast majority of household cases reported in the literature occurred among individuals living with one or more family members who worked in industries characterized (sic) by high exposures, nearly always to amphibole fibers (sic), and frequently during the 1930s–1960s”. It was also stated that for the United States “using these cases to characterize the risks associated with exposures that have occurred since about 1975 is not recommended, since not only have workplace asbestos concentrations decreased as a whole, but the use of amphiboles has also dropped dramatically and regulations that forbid removal of contaminated clothing from the workplace have been in place since the early 1970s”.

AimThis chapter summarises the types and potential magnitude of inhalation exposures to asbestos in the UK. An understanding of current background environmental concentrations and the extent of the resulting exposures may be relevant to evaluating the significance of risks posed by ACSs.



In summary, para-occupational exposure was previously a significant risk in industries where workers were permitted to return home wearing their work overalls. In the UK, workers known to be working with asbestos (or at risk of asbestos contamination) are required to change from work overalls before going home.

Donovan et al (2012) also concluded that the available data did not suggest chrysotile was a significant cause of disease for household contacts. This is consistent with the differences in risk between chrysotile and amphibole asbestos as described later in this guide (see Chapter 14).

6.3 envIROnmentAl expOSuReSWidespread use of asbestos has resulted in detectable background environmental concentrations of asbestos, particularly in urban areas. For instance, based on data mainly collected in 1980s, WHO (2000) reported concentrations ranging “from below one hundred to several thousand fibres per m3”, equivalent to <0.0001 to >0.001 f/ml. Such background concentrations (both indoors and outdoors) lead to non-occupational or environmental exposures of the general population in most western countries, including the UK. It is widely recognised that asbestos fibres are detected in the lungs of urban dwellers at post mortem.

The potential health implications of environmental exposure have been estimated by extrapolation of the exposure-risk models derived from occupational epidemiology studies and have been the subject of much speculation.

People with no obvious occupational exposure to asbestos have succumbed to mesothelioma. Annually, 100 to 200 deaths may be attributed to ambient, or unreported, exposure to asbestos (Rake et al, 2009 and Peto et al, 2009). As CAR continues to reduce occupational exposures, the relative importance of non-occupational and environmental exposures may increase. In the future, the contribution of such environmental exposures to cases of asbestos-related diseases may increasingly become the focus of compensation claims, particularly where obvious occupational exposures cannot be identified. However, currently there are no plans for statutory regulation of such environmental exposures.

6 .3 .1 Background concentrations in outdoor airAccurate measurement of the concentration of asbestos in outdoor air is difficult and often confounded by weather conditions.

Measurements collected in the 1980s (Table 6.1) suggested that background concentrations of asbestos in outdoor air in urban areas were around 0.0001 f/ml while those in more rural locations were roughly 10 times lower. Background concentrations were also reviewed in by HEI (1991) in the US and Shuker et al (1997) in the UK. The latter noted that concentrations of respirable fibres in air were generally in the range 0.0001 to 0.000001 to fibres/ml, but also noted that “a significant proportion of the recorded data comprises concentration levels below the detection limit of the method of analysis”. More recently, Lee and Van Orden (2008) measured air concentrations within buildings in the US and provided outdoor measurements for comparison. These measurements are in-line with those previously cited.

However, most data pre-date the end of asbestos importation, the bans on the use of asbestos in vehicle brakes, and the parallel improvements in asbestos management practices over the past 20 years. Also, although little more contemporary data exists, it is likely that environmental concentrations of asbestos in the UK are now lower than those previously reported. However, environmental concentrations will still result in some degree of background exposure to the UK population.


CIRIA, C73348

Table 6.1 Background asbestos concentrations reported in indoor and outdoor air (after WHO, 2000)

Outdoor air1,2

Rural areas (remote from asbestos emission sources) Below 100 F/m3

Urban areas General levels may vary from below 100 to 1000 F/m3

Near various emission sources the following figures have been measured as yearly averages

�� downwind from an asbestos-cement plant 300m: 2200 F/m3, at 700 m: 800 F/m3, at 1000 m: 600 F/m3

�� at a street crossing with heavy traffic 900 F/m3

�� on an express-way, up to 3300 F/m3

Indoor air1,2

In buildings without specific asbestos sources Concentrations are generally below 1000 F/m3

In buildings with friable asbestos Concentrations vary irregularly, usually less than 1000 F*/m3 are found but in some cases exposure reaches 10000 F*/m3

notes:

F* In the final cell of this table, this indicates fibres counted by optical microscopy, all other measurements are by electron microscopy methods.1 The data represents a range of different sampling and analytical techniques and was collected for a variety of purposes. A direct

comparison between different values is not appropriate.2 Much of this data relates to measurements collected in the 1980s. The more stringent restrictions and controls implemented in many

countries since then mean that current background concentrations would be expected to be lower than those cited.

6 .3 .2 Background concentrations in indoor airFor obvious reasons, indoor air concentration data tends to be biased towards buildings known to contain asbestos. Mean indoor concentrations of 0.00051, 0.00019 and 0.0002 f/ml in schools, homes and public buildings were estimated for the US during the 1980s (HEI, 1991). WHO estimates of background asbestos fibre concentrations in indoor air are presented in Table 6.1. In the UK, potential indoor exposures have been reviewed by Shuker et al (1997).

In the US, ATSDR (2001) concluded that “In general, levels of asbestos in air inside and outside buildings with undisturbed asbestos-containing materials are low, but indoor levels may be somewhat higher than outside levels”.

Smith and Saunders (2007) calculated that an urban population exposed to 0.00003 f/ml in outdoor air would inhale roughly 15 million fibres over a lifetime (assuming a 70 year lifespan and a breathing rate of ~20m3 per day, and that all fibres in the breathed volume are inhaled). They also calculated that a population exposed to median concentrations of 0.0004 to 0.0005 f/ml in indoor air could inhale roughly 200 million fibres over a lifetime (with the same assumptions).

Reductions in the use of ACMs in contemporary homes and buildings are likely to have reduced indoor exposures since the 1980s, but a large proportion of the UK housing stock was constructed before the ban on the importation and use of asbestos in the UK. So, as residents etc spend a greater proportion of their time indoors, indoor exposures may be higher than those from background concentrations of asbestos in outdoor air and should not be ignored.

6 .3 .3 Background concentration of asbestos in soil and made ground

There are well-documented examples of naturally-occurring asbestos being found in soils in several countries, including the El Dorado Hills and Clear Creek in California or the Amiandos area of Cyprus. However, there is little collated information on the occurrence and distribution of asbestos in soils in the UK, whether from natural or anthropogenic sources.

It is unclear to what extent asbestos minerals are present in the igneous rock formations of the UK, and to what extent (if any) these have been mined. Small amounts of naturally-occurring asbestos have been reported on a localised basis, for example actinolite has been collected in Devon (Addison et al, 1997).



Such deposits have not supported large-scale mining, but there are some limited reports of historical small-scale mining in parts of Scotland (Johnston and McIvor, 2000). Apart from these localised sources, naturally-occurring asbestos has not been reported in UK soils.

Defra funded research, focusing on England, undertaken by a team led by the British Geological Survey (BGS) reported that a “lack of data on the occurrence of naturally occurring asbestos minerals in soil meant it was inappropriate to determine [normal background concentrations] NBCs for asbestos” (Johnson et al, 2012). However BGS reported that “unexploited areas of natural asbestos in England can only be considered to be a very minor source contributing to the normal background (Studds, undated). The lack of information on asbestos in soils, outside targeted site investigations, cannot be considered a significant gap in knowledge. For asbestos minerals the question is not what constitutes a NBC, rather whether such harmful minerals are present or absent.” (Ander et al, 2011).

Where asbestos has been identified in soils, it is almost invariably the result of man’s activities. The wide-spread historical use of ACMs (see Section 4.2) is likely to have resulted in some degree of background concentration of asbestos in urban soils but there is no published data available to quantify its distribution. Work conducted in a housing development in the West Midlands (Robertson et al, 2011) suggests that background concentrations in soil are generally below the detection limit of current analysis techniques (ie <0.001 per cent).

noteNon-asbestos amphibole minerals are common in UK geology. Natural weathering of such minerals can generate cleavage fragments and crystals, which are common components of UK soils and have been reported as being difficult to distinguish from asbestos (Addison, 2009).

Summary

�� historically, occupational and para-occupational exposures have been the most important sources of asbestos exposure in the UK and have been the focus of regulatory efforts to prevent exposure to reduce the future occurrence of asbestos-related deaths

�� the widespread use of ACMs in the past has resulted in environmental exposure of the UK population to a low background concentration of airborne asbestos fibres, especially in urban environments

�� the current background concentration of asbestos fibres in outdoor air in the UK is not known. Most published measurements of ambient asbestos in air concentrations were made over 20 years ago and do not relate to the UK. Banning the use of ACMs and improving management control will have led to a decline in asbestos exposures over recent decades

�� ACMs are still potentially present in a large number of domestic and commercial premises and this is also likely to be resulting in background exposure of the UK population

�� in general, naturally-occurring asbestos is not commonly found in UK soils. Most ACSs in the UK are the result of anthropogenic sources originating from imported asbestos

�� there is little information on the concentration and distribution of ACSs in the UK. Background concentrations are believed to be low but asbestos is commonly found in brownfield sites.


CIRIA, C73350

7 existing uK and other national guidance on asbestos in soils

Although there are numerous documents considering the identification and management of ACMs in buildings and building materials published by the HSE, these are primarily concerned with occupational health and safety legislation. As they are not directly relevant to long-term environmental exposures and do not specifically consider ACSs they are discussed in other chapters of this guidance.

There is extensive guidance relating to the investigation assessment and remediation of contaminated soils (eg Defra, 2012a). This provides a generic framework for dealing with ACSs but does not address specific issues that arise from the particular properties of asbestos and ACMs. The only existing UK guidance specifically considering ACS was published by ICRCL (1990), and by the AGS (2013).

A brief commentary on other national guidance (from Australia, the Netherlands and the USA) indicates how that guidance may inform soil risk assessments in the UK, and points out where applicability to the UK is likely to be constrained by differences in national policies or environmental circumstances. This guidance is reviewed in more detail in Appendices A3, A4 and A5.

7.1 ‘ASbeStOS On COntAmInAted SIteS’ (ICRCl, 1990)ICRCL 64/85 was first published in 1985, and later updated in 1990 (ICRCL, 1990). Although this is now outdated (particularly with respect to asbestos-related legislation and the risks associated with low-level asbestos exposure), it remains the most relevant guidance on the investigation and management of asbestos-containing soil in the UK.

ICRCL (1990) aimed to provide “general guidance on the identification, assessment and treatment of” formerly industrial premises or waste disposal sites with asbestos. It advocated a similar phased investigation process to that commonly used at any potentially-contaminated site. However, it provides little practical detail on the procedures that should be followed at such sites.

ICRCL (1990) recommended desk study and site reconnaissance, including an assessment of the types of documents and information sources that are commonly consulted (RPS Consultants, 1994) to identify the potential for asbestos in soil. This would be followed by a preliminary visual inspection of the surface and exposed areas of the site during which any suspected asbestos or fibrous materials are recorded for subsequent sampling and identification. It also suggests that wetting the soils makes any asbestos more visible.

Where asbestos is suspected to be present below the surface (such as infilled areas, underground structures etc), a field investigation based on a systematic sampling grid is recommended within the suspected areas. Grid spacing should be sufficient to provide adequate characterisation of the suspected area. Sampling should be conducted to a depth of at least two metres (greater depths may be appropriate if any buried asbestos is likely to be disturbed by landscaping or construction activities) using either trial pits or borehole techniques. The latter is preferable if the site is heavily contaminated as health and safety risks are considered more easily controlled.

The publication of the second edition (ICRCL, 1990) was prompted by the findings of research conducted by Addison et al (1988), which showed that soils containing as little as 0.001 per cent free asbestos fibres could liberate airborne fibre concentrations greater than 0.01 f/ml (ie the clearance indicator level) when the dust concentration was less than 5 mg/m3, the contemporary occupational

AimThis section summarises existing UK guidance relating to ACSs. Guidance available in the US, the Netherlands and Australia is also discussed along with its applicability to the UK context.



exposure limit for nuisance dust. Based on this report, ICRCL (1990) recommended that where discrete fragments of asbestos are present, the affected area should be regarded as contaminated and appropriate measures implemented. However, where visible asbestos is not present, samples should be analysed using methods with a limit of quantification for respirable fibres of at least 0.001 per cent by weight. Where samples exceed this level, further confirmatory sampling in the vicinity is recommended to determine if the results indicate serious contamination. The document concludes that even on sites where asbestos is not found during such sampling, it cannot be concluded that it is not present elsewhere.

Very little detail is provided with respect to assessing the risks posed by any asbestos identified in the field investigation. In particular, no guideline values or assessment criteria were recommended by the ICRCL (1990). A concentration of 0.001 per cent (of asbestos in soil) is cited as a level potentially able to generate significant airborne fibre concentrations. So, further investigation or assessment is justified above this level. It is also recommended as a minimum limit of detection for soil analysis. It is not a level below which ICRCL considered that risks are acceptable or below which potential civil liabilities could be assumed to be negligible. So, it is not an appropriate generic assessment criterion for ACSs.

The document recommends that as part of a soil risk assessment consideration should be given to the:

�� amount and form of the asbestos present in the soil

�� location of the site, and its position in relation to housing, schools etc

�� present use of the land

�� ease of public access

�� proposed future use of the land, including construction activities.

Finally, the document outlines contemporary remedial methods considered appropriate for ACSs. These included excavation and disposal, re-burial on site, capping, compaction, solidification and vitrification. The option of sealing affected areas under buildings, roads, pavements, parking etc is also discussed. However, overall it is recommended that sites affected by asbestos in soil should be put to industrial or commercial uses in preference to residential, and that any asbestos found and actions taken should be fully documented and cross-referenced to land ownership and planning records for future reference.

The requirement for adequate and appropriate health and safety precautions in accordance with relevant legislation is repeatedly highlighted in ICRCL (1990). In particular, precautions are needed to prevent the spread or off-site migration of asbestos fibres and contamination and to minimise the generation of dust, eg by ‘damping down’ work areas. Decontamination facilities for workers and vehicles are also recommended for ‘large-scale excavation’. Requirements for appropriate health and safety risk assessments, health surveillance for worker and compliance monitoring are also mentioned based on legislation and occupational exposure limits existing at that time. However, this legislation and exposure limits have since been superseded.

7.2 AGS InteRIm GuIdAnCeAGS (2013) suggested a process for completing a site investigation asbestos risk assessment (SIARA) to ensure site investigation personnel are adequately protected. It suggests that where there may be a risk that works release airborne asbestos concentrations above 0.1 f/ml the works are “almost certainly notifiable under CAR 2012” and where there is a risk of releasing concentrations above this level “the work is almost certainly Licensable under CAR 2012”. The SIARA guidance is intended to make AGS members aware of their responsibilities under CAR 2012 and to offer a practical means of discharging their duties pending the publication of new guidance from HSE.

noteAlthough contemporary methods for the analysis of bulk materials could theoretically achieve a limit of detection of 0.001 per cent, such methods could not accurately determine asbestos concentrations in soil. This significantly inhibited application of the guidance. Suitable quantitative methods have subsequently been developed (Davies et al, 1996, and Schneider et al, 1998), and are now available from several commercial soil analysis laboratories in the UK.


CIRIA, C73352

The SIARA site usage form illustrates low, medium and high risk uses:

�� low risk: greenfield sites

�� moderate risk: sites developed, altered or refurbished in 1930s to 1980s. Landfills. Made ground (fill). Allotments

�� high risk: all buildings and refurbishments 1960s to 1970s. Asbestos product works.

The SIARA site features form illustrates low, medium and high risk features:

�� low risk: undisturbed hard cover

�� moderate risk: crushed recycled aggregate, building and demolition waste, backfilled basements, bare soil with potential to generate dust in dry condition

�� high risk: visible asbestos. Dust (especially demolition and where nearby asbestos working/storage).

7.3 ApplICAbIlIty Of OtheR GuIdAnCe tO the uKThe UK generally promotes a phased approach to the investigation and risk assessment of potentially contaminated sites, which is similar to that in Australian, Dutch and US EPA guidance for asbestos in soils (see Appendices A3, A4 and A5 respectively). Consequently, the basic assessment process recommended in such guidance, and potentially details of sampling techniques etc, may be directly applicable to sites in the UK.

However the risk evaluation stage is likely to be different for the following reasons:

�� the Dutch framework is based on national criteria for airborne asbestos fibres concentrations. Recommendations based on a re-analysis of asbestos epidemiology have been made for a substantial reduction in these levels (Health Council of the Netherlands, 2010). No analogous levels have been set for the chronic exposure of the UK population and existing guidance states that the clearance indicator threshold cannot be used as “an acceptable permanent environmental level” (HSE, 2008). Use of the Dutch thresholds is likely to require significant clarification in order to demonstrably comply with UK policy and guidance

�� the US EPA framework appears to be derived for a drier, dustier climate than is commonly encountered in the UK and adopts risk models and approaches that may not be compatible with UK policy and guidance

�� the Australian framework is essentially based on that proposed in the Netherlands with additional pragmatic policy assumptions to account for Australia’s drier climate and other country-specific considerations.

The US and Dutch frameworks appear to be aimed more towards assessing risks at existing sites rather than predicting potential risks at proposed new developments. For example, both frameworks recommend direct measurement of asbestos contamination within existing buildings. While such approaches may be relevant to assessments under Part 2A of the Environmental Protection Act 1990, they would be very difficult to apply in a redevelopment scenario, where such a building does not yet exist.

In the absence of detailed UK guidance, contaminated land practitioners can develop site-specific approaches to the assessment of risks from ACSs by referring to other international guidance. However, while the general principles and techniques described in such guidance may seem transferable, care should be taken to ensure that such guidance is compatible with existing UK policy, guidance and legislation (including CAR).

Part 2A Statutory Guidance (Defra, 2012a) requires soil risk assessments to be “based on information which is: (a) scientifically-based; (b) authoritative; (c) relevant to the assessment of risks arising from



the presence of contaminants in soil; and (d) appropriate to inform regulatory decisions in accordance with Part 2A … ”. As the planning system is required to ensure that land is ‘safe’ and ‘suitable for use’, and “after remediation, as a minimum, land should not be capable of being determined” under Part 2A (DCLG, 2012), soil risk assessments under planning should also comply with these requirements. With respect to the assessment of risks from ACSs, if models, techniques or threshold values described in international guidance are to be used in the UK, practitioners will need to justify and document that they are ‘scientifically-based’, ‘authoritative’ in the UK (ie contradictory guidance has not been published by the UK Government, its agencies or advisory committees), and is ‘relevant’ and ‘appropriate’ to the site-specific circumstances. Similar justifications are required where non-UK thresholds (eg Dutch values) or risk assessment tools (eg RBCA) are used for any other contaminant. In the case of asbestos, this should include consideration of:

�� differences in national policy, guidance and assumptions relating to soil risk assessment

�� differences in asbestos risk modelling and toxicological approaches

�� potencies of the different asbestos types (eg chrysotile <<amosite <crocidolite)

�� differences in climate (eg temperature, rain fall) and soil type

�� whether the adopted approach is likely to underestimate or overestimate risks in a UK context

�� appropriateness and applicability of thresholds or toxicological benchmarks under the appropriate UK legal context (eg Part 2A and planning).

Failure to consider these issues on a case-by-case basis may result in significant legal and financial liability for both clients and contractors, for example, if Part 2A or planning decisions are challenged on the basis that the soil risk assessment contradicts existing authoritative UK advice.

Summary

�� the only available previous published UK guidance specifically on ACSs and made ground is contained in ICRCL (1990)

�� this guidance from ICRCL stresses the potential for ACSs to liberate potentially hazardous levels of airborne fibres but it does not provide enough guidance to enable the risk-based management of such soils

�� some relevant guidance is available internationally, notably from the US, the Netherlands and Australia. Although this guidance is informative, many technical aspects are driven by national policy decisions that are not applicable in the UK.


CIRIA, C73354

8 Complying with CAR: risk assessments, licensing and training

8.1 CAR RISK ASSeSSmentSStaff safety should be paramount at all times and a precautionary approach should be adopted if in doubt. This applies to all the expected safety hazards on brownfield and construction sites, chemicals and other hazards from soil contamination and asbestos.

CAR requires an assessment of work which exposes employees to asbestos that specifically addresses all potential risks to workers for any work involving asbestos – the CAR risk assessment.

There is a wealth of helpful guidance on the CAR regulations and risk assessments on the HSE website, including asbestos essentials (see Useful websites). This chapter does not attempt to repeat this, but rather it concentrates on where risk assessments may be relevant in relation to sites (potentially) affected by asbestos contamination in the soil and some special features.

The main activities with a potential for asbestos exposure during work on brownfield sites suspected of containing asbestos are site reconnaissance visits, site investigations (whether or not the investigation is directed at asbestos) and site remediation. CAR risk assessments are needed for all three but these need not be onerous and at the investigation stages, they may be an adjunct to the health and safety risk assessment. (Laboratories undertaking sample analysis should have appropriate risk assessments and asbestos control procedures but this is not specific to contaminated land and is not addressed in this guide.)

Among other requirements, the risk assessment must:

�� identify the type of asbestos to which employees are liable to be exposed, where possible, or assume it is present and is not chrysotile alone

�� determine the nature and degree of exposure that may occur in the course of the work

�� set out the steps to be taken to prevent that exposure or reduce it to the lowest level reasonably practicable

�� consider the effects of control measures that have been or will be taken.

It should include any additional information (such as the desk study) that may be needed to complete the risk assessment. As it is not known whether asbestos is present at the site reconnaissance and investigation stages, the employer should assume that asbestos (and not just chrysotile) could be present and observe the applicable provisions of CAR.

For all investigation and remediation of ACSs, a detailed written work plan should be produced and followed. The HSE website and CAR define what this should contain.

The CAR risk assessments for specific investigations or remediation projects, will determine whether or not work is ‘licensable work’ (LW), ‘notifiable non-licensable work’ (NNLW) or ‘non-licensed work’ (NLW). Licensing is discussed further in Section 8.2.

AimThis chapter outlines CAR risk assessments and where they should be applied in relation to assessing and remediating brownfield sites. It identifies the different classifications of work with asbestos under CAR and discusses the legal requirements for asbestos awareness training for all involved in the investigation and management of ACSs. It also discusses the potential requirements for suitable proficiency training relating specifically to ACSs.



Training requirements are also defined by the CAR risk assessment. Such requirements are discussed in more detail in Section 8.3.

8 .1 .1 During site reconnaissance visitsInvestigators may inadvertently disturb asbestos during site reconnaissance visits. The desk study should consider the likely extent, types, forms, potential for fibre release, location and depths of any asbestos contamination. This information should inform the CAR risk assessment. It is likely that asbestos exposures during reconnaissance visits to most sites will be very low and precautions taken should be simple and proportionate. For example, at most sites controls may include avoiding stirring up dust during the visit, cleaning footwear before leaving site, removing and bagging any overalls for disposal/laundering. However, at high risk sites where large amounts of asbestos are suspected further controls, including respirators and hygiene facilities may be appropriate.

8 .1 .2 During site investigationsIf a site is suspected of being contaminated by asbestos, a CAR risk assessment is required for any on-site investigation involving ground disturbance, whether or not asbestos is the subject of that investigation.

The CAR risk assessment should include consideration of information from the desk study, the site walkover and the proposed method of investigation.

Control measures should be designed to control the hazards on that site. Asbestos should not be considered in isolation. The asbestos mitigation measures taken should be proportionate. In general, greater control measures will be required if more friable ACM is expected, higher concentrations of asbestos are likely or there is an increased likelihood of amphibole asbestos. For example, depending on the site and the investigation procedures, respirators may be deemed necessary, disposable overalls may be required, segregated welfare units may be needed. Wetting ground before sampling will reduce fibre release but may not be appropriate for other analytes. It is important that investigation techniques, particularly on high risk sites, are designed to minimise soil disturbance, asbestos spread and dust and fibre generation. Careful design of the investigation and selection of sampling procedures will reduce the need for investigations to be deemed LW.

8 .1 .3 During remediation, redevelopment and construction activitiesWith respect to remediation, the findings of any site investigation should also be considered within the CAR risk assessment. In particular, the extent of asbestos contamination, asbestos type, ACMs found and remediation method statement should all be considered, in addition to the desk study.

Where previous risk management activities involved the use of capping layers and break layers, serious consideration should be given to leaving these areas undisturbed during remediation and redevelopment.

The remediation of sites affected by asbestos may involve ‘licensable work’, ‘notified non-licensable work’ or simply non-licensable work. The risk assessment and work plan will be site-specific and must cover all aspects of the remediation involving ACS.

The likely airborne fibre concentrations released from ACSs will depend on the types of activities involved (hand digging, mechanical digging, pneumatic drilling etc), the amount and types of ACMs being disturbed and the level of mitigation measures employed. Vehicular traffic is another possible source of dust and fibres, particularly during dry periods. Good site awareness, site management, asbestos-specific mitigation measures and training will reduce worker exposure to airborne dust and fibres. In order to avoid subsequent civil liabilities, mitigation measures need to prevent exposure of neighbouring residents and the public to levels, which might be deemed ‘significant’ in the future. This is a more stringent requirement than currently necessary under CAR.


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The risk assessment will define the mitigation measures required, the need for, and specification of, personal protective equipment (PPE) and decontamination facilities (eg clean and dirty areas for site workers, showering facilities, disposable PPE or laundering clothing), and the need for air monitoring (see Chapter 12). The required mitigation measures will depend on the working methods, the nature and extent of the asbestos and the ACMs present and ground conditions. Mitigation measures to minimise asbestos exposures and prevent the spread of asbestos may include ‘damping down’ of all site materials, managing stockpiles, segregated areas, wheel washes, road wetting and road cleaning, as appropriate.

Remedial projects usually involve multiple contaminants and often involve remediation of both soils and groundwater etc. It is rare that only ACSs require remedial intervention, indeed asbestos may only be a minor element of a much larger remedial scheme. Asbestos remediation contractors and asbestos specialists engaged to implement asbestos investigations and works, should normally be part of a wider specialist contaminated land team and have awareness training of the risks from chemical contamination.

8.1.4 Respiratoryprotectiveequipment(RPE)The need for, and type of, RPE required, is defined by the CAR risk assessment. Respirators are the last line of defence against hazardous materials. To work effectively, they need to fit correctly, be clean, in good condition and be well maintained.

If it is deemed that RPE is necessary, the correct respirators should be worn. HSE (2013b) advises that RPE should have an assigned protection factor of 20 or more for all work with asbestos. In certain instances, full face-piece, positive pressure respirators with a protection factor of 40 are necessary (to EN 12942:1998, TM3). People wearing these respirators should be clean shaven.

Employers must ensure that all workers have appropriate RPE, up-to-date face fit tests and training in when and how to wear, use, clean and store RPE correctly. Also, employers and employees should ensure that all non-disposable RPE is in good working order and serviced according to the manufacturer’s requirements.

Table 8.1 Suitable types of RPE for most short duration non-licensed asbestos work

Disposable respirator to standards EN149 (type FFP3) or EN1827 (type FMP3)

Half mask respirator (to standard EN140) with P3 filter

Semi-disposable respirator (to EN405) with P3 filter

The equipment in Table 8.1 is not suitable for people with beards or stubble, or for long periods of continuous use, and powered equipment (eg meeting EN12941:1998) is normally needed for such situations.

There are occasions in non-licensed and licensed work where other chemical hazards are present and respirators are also required to protect against these. In these circumstances, disposable respirators are unlikely to be appropriate and combined dust and vapour respirator filters are required for half face-piece or full face-piece respirators. Employers should consult HSG53 (HSE, 2013b) in these circumstances to ensure employees are properly protected.

8.2 lICenSInGCAR defined certain types of activities involving asbestos as ‘licensable work’ (LW) or as ‘notifiable non-licensable work’ (NNLW). All other work would be ‘non-licensable work’ (NLW).



LW is defined as:

�� work where exposure is not ‘sporadic and low intensity’

�� work where the risk assessment cannot demonstrate that the control limits (four hour and 10 minute limits) will not be exceeded

�� work on asbestos coating

�� work on AIB or insulation where risk assessment is either of first two points above or not of short duration (where short duration is defined for any work liable to disturb asbestos as taking less than two hours per week (including ancillary work) and no one person carries out that work for more than one hour).

NNLW includes work with:

�� AIB or asbestos insulation of short duration that is not licensable

�� fire-damaged asbestos cement or asbestos cement damaged so as to create significant dust and debris

�� asbestos ropes, yarns, woven cloths in poor condition or handling cutting or breaking up the materials

�� asbestos papers, felts and cardboard in poor condition, unencapsulated or not bound into another material.

Work with weathered asbestos cement, air monitoring and collecting samples of ACM in buildings would not normally be notifiable.

It is impossible to specify definitively what activities will and will not be licensable. This decision should be made as part of the CAR risk assessment. CAR is not primarily aimed at work with ACSs and there is little published information on airborne asbestos concentrations during work with ACSs. Nevertheless, CAR will require some remediation projects, and occasionally site investigations, to be LW. Investigations on other sites may involve NNLW. The decision as to whether work is LW or NNLW should be made during the CAR risk assessment by those in charge of the brownfield site investigations and remediation projects.

8.3 tRAInInG RequIRementSThose involved in the investigation, assessment and management of sites where ACSs are known, or suspected, to be present will need training. This is to both comply with the information, instruction and training requirements under CAR and to ensure that they are technically competent to conduct the specified works. The amount and content of the training will vary depending on their role, experience and duties. It is the role of the employer to identify the information, instruction and training needed on a case-by-case basis.

Those managing or supervising site work, particularly those preparing health and safety documentation, may need additional instruction in their legal responsibilities and how to complete the suitable and sufficient method statements and CAR risk assessments.

The information, instruction and training requirements of CAR are described in Regulation 10, which begins:

“Every employer shall ensure that adequate information, instruction and training is given to those of his employees –

(a) who are or who are liable to be exposed to asbestos, or who supervise such employees, so that they are aware of –

noteThe HSE website gives full information on licensed and non-licensed asbestos work: www .hse .gov .uk

Asbestos essentials has helpful guidance: www .hse .gov .uk/asbestos/essentials/index .htm


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(i) he properties of asbestos and its effects on health, including its interaction with smoking,

(ii) the types of products or materials likely to contain asbestos,

(iii) the operations which could result in asbestos exposure and the importance of preventive controls to minimise exposure,

(iv) safe work practices, control measures, and protective equipment,

(v) the purpose, choice, limitations, proper use and maintenance of respiratory protective equipment,

(vi) emergency procedures,

(vii) hygiene requirements,

(viii) decontamination procedures,

(ix) waste handling procedures,

(x) medical examination requirements, and

(xi) the control limit and the need for air monitoring.”

Any training needs to be given at regular intervals to be relevant to the work being undertaken and updated to reflect any significant changes in the type of work or working methods.

Asbestos health and safety courses are offered by a number of providers in the UK. The HSE website lists, but do not endorse, several umbrella organisations that audit and/or approve asbestos training providers and courses (see Useful websites). However, such training has generally been developed for those working directly with ACMs in buildings (ie the construction, building maintenance and demolition industries) and is unlikely to be suitable for employees working with ACSs. They would not, for example, include the problem of identifying ACMs buried in soils.

8 .3 .1 Unique requirements for site reconnaissance, site investigation and remediation workers

Expertise and competence in recognising potential ACMs in soils is vital for a reliable site reconnaissance and site investigation, both in terms of worker safety and effective delineation of any asbestos contamination. So, in addition to the statutory training required under CAR (see Section 8.3.2) ground workers are likely to need further proficiency training on the difficulties of identifying ACMs within a soil matrix.

Recognising potential ACMs within buildings can be challenging, but the recognition of potential ACMs is typically more difficult where fragments have been buried for some time and may have become the same colour as the surrounding soil etc. Also, soils and made ground contain a wide range of non-ACM particles, including natural cobbles and gravels as well as fragments of glass, brick, tile, ceramics, ash, clinker and other wastes, all of which will be smeared with soil. Consequently, field experience in the identification of potential ACMs in soil will be a vital element of any such training.

However, training for ground workers may also need to address other issues unique to the contaminated land industry such as:

�� what site investigation techniques are most likely to release airborne fibres from soils

�� under what conditions is the release of fibres more likely

�� potential control measures applicable to ACSs, such as damping down and temporary surface covers

�� how to take representative samples of ACSs safely

�� how to label and package soil samples for transport to the laboratory

�� what analytical tests are available, their limits of detection/quantification and when to schedule them.



Figure 8.1 Sample containing asbestos (courtesy DETS Laboratories)

8 .3 .2 Health and safety training required under CARTraining requirements are discussed in the CAR ACOP (HSE, 2013a). This recognises three types of information, instruction and training:

�� asbestos awareness

�� non-licensable work (including notifiable non-licensable work)

�� licensable work with asbestos.

8.3.2.1 Asbestos awareness trainingAwareness training is for those who may disturb asbestos while carrying out their normal work or for those who instruct, or have influence on the methodology of such work. It ensures that people, and those they are managing or instructing, know how to avoid the risks of, and protect themselves from, asbestos. The ACOP suggests that awareness training is needed unless it can be demonstrated that the premises are free of ACMs. Awareness training is only intended to allow employees to recognise potential ACMs, avoid disturbing them and to then initiate established emergency procedures.

Awareness training generally includes basic information of the properties of asbestos and its effects on health, the types, uses and likely occurrence of asbestos and ACMs, how to avoid exposure and emergency procedures to follow if suspected asbestos is encountered. Full details are provided within the ACOP.

Awareness training alone is not enough for anyone working with, or likely to disturb asbestos or ACMs. Asbestos awareness training alone may be appropriate for employees undertaking site reconnaissance, site investigation or remediation tasks at sites where there is a low probability of encountering asbestos. However, to be effective, such training would need to address the difficulties of identifying ACMs within a soil matrix.

8.3.2.2 Training requirements when ACMs will be disturbedWhere it is known or likely that work will involve disturbing ACMs, task-specific information, instruction and training needs to be provided to employees in addition to basic awareness training. Such training is likely to be needed by employees undertaking site reconnaissance, site investigation or remediation tasks at sites where the probability of encountering asbestos is not low. The exact requirements will be dictated by the classification of the work (ie licensable or non-licensable work) and the findings of the CAR risk assessment.

As a minimum, employees should receive information relating to the risk assessment and work plan but may also need, for example, details of the control measures employed, details of air monitoring and results and results of any RPE face fit tests etc.


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In addition, this level of instruction and training should also include an introduction to the relevant regulations, ACOPs and guidance, which tasks or activities could result in asbestos exposure, how to assess the risks, safe work practices, control measures to be implemented and any PPE requirements, how to use the PPE and the relevant control limits and the purpose of occupational air monitoring. Instruction and training should also include how the spread of asbestos will be limited, decontamination and waste handling protocols and the emergency procedures to take if, for example, larger quantities of suspected ACMs are encountered than anticipated. Full details are provided within the ACOP.

For awareness training, the difficulties of identifying ACMs in a soil matrix would need to be addressed. Most existing training, which is generally based on the generic requirements for licensed or non-licensed work, is unlikely to meet all the needs of ground workers and personnel involved in site reconnaissance, site investigation and site remediation activities.

8.3.3 ProficiencytrainingIn addition to health and safety training, some staff involved in the technical identification on site of ACMs, sampling and analysis may require technical proficiency training (sometimes referred to as competency training).

The British Occupational Hygiene Society (BOHS) have generated recognised syllabi for several proficiency training modules (Table 8.2), which can be delivered by third party providers registered with BOHS. Alternatively, equivalent syllabi to some of these modules have been prepared by the Royal Society of Public Health (RSPH), which are offered by the Asbestos Testing and Consultancy (ATAC). BOHS or RSPH qualifications are required for UKAS accreditation of laboratories and building surveyors and analysts. However, these qualifications do not cover all that is needed for asbestos in soil investigations. BOHS are currently developing further curricula that would include asbestos in soil.

Figure 8.2 Examples of asbestos and ACMs in soils and made ground (courtesy VSD Avenue, a consortium comprising VolkerStevin Ltd, Sita Remediation NV and DEME Environmental Contractors BV)



Figure 8.2 Examples of asbestos and ACMs in soils and made ground (courtesy VSD Avenue, a consortium comprising VolkerStevin Ltd, Sita Remediation NV and DEME Environmental Contractors BV) (contd)

Table 8.2 Existing asbestos-related BOHS proficiency training modules

P401 Identification of asbestos in bulk samples (PLM)

P402 Buildings surveys and bulk sampling for asbestos (including risk assessment and risk management strategies)

P403 Asbestos fibre counting (PCM) (including sampling strategies)

P404 Air sampling of asbestos and MMMF and requirements for a certificate of reoccupation following clearance of asbestos

P405 Management of asbestos in buildings

P406 Supervision and management of the safe removal and disposal of asbestos

P407 Managing asbestos in premises, the duty holder requirements

8 .3 .4 Training vs . competenceHSE (2005) sets out guidance intended for analysts undertaking asbestos work. This includes the specification for training but notes that “Training alone does not make people competent. Training must be consolidated by practical experience so that the person becomes confident, skilful and knowledgeable in practice on the job.” For example, to achieve UKAS accreditation as a building surveyor (which is non-mandatory), a trainee asbestos surveyor for buildings will normally accompany an experienced surveyor for at least six months, and will then lead surveys and be audited to verify his/her competence.

While there is no comparable requirement to demonstrate competence for those surveying ACSs, it is critical that those undertaking this type of work are competent to do it. Persons undertaking these types of tasks should be able to provide the employer with details of relevant field experience alongside any training and examples of previous work and references.


http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/P401_Syllabus.pdf

http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/P402_Syllabus.pdf

http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/GC.1__010310__P403_Syllabus.pdf

http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/GD.1__010310__P404_Syllabus.pdf

http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/GE.1__010310__P405_Syllabus.pdf

http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/GF.1__010310__P406_Syllabus.pdf

http://www.bohs.org/uploadedFiles/Development/Examinations/Pages/GX.1%20%28010311%29%20P407%20Syllabus.pdf

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Summary

�� where work involves (or is likely to involve) contact with asbestos, then CAR requires a risk assessment to be made

�� the decision as to whether work is LW or NNLW should be made during the CAR risk assessment

�� it is likely that CAR will require some remediation work and occasionally work involved in site investigations to be LW

�� it is likely that investigations and remediation on some other sites may involve NNLW

�� only licensed contractors can conduct LW. This is likely to increase costs for such activities

�� all staff likely to encounter asbestos at work require appropriate information, instruction and training to comply with CAR

�� most currently available training does not adequately address the difficulties involved in identifying ACMs with soils

�� asbestos awareness training allows workers to avoid ACMs and implement emergency procedures if it is encountered. This may be sufficient for ground workers at sites were asbestos is not suspected to be present

�� at sites were asbestos is suspected or known to be present, in addition to awareness training, ground workers require more detailed, task-specific information, instruction and training. The exact requirements will depend on the CAR risk assessment based on factors such as the nature of the tasks, the amount and nature of asbestos in the ground and an individual’s previous experience and training

�� additional proficiency training may be required, for example to ensure staff can identify potential ACMs in soil and made ground

�� there are currently no recognised syllabi for such training and appropriate training will need to be provided in-house or as bespoke training from a third party provider

�� unless and until appropriate commercial training relating to asbestos in soil becomes available, employers will need to identify appropriate levels of instruction, information, training and supervision through a ‘training needs analysis’.



9 Releaseofairbornefibresfromasbestos-containing soils (ACSs)

Asbestos, including ACSs, only presents a risk to health if airborne fibres are released into the atmosphere (Chapter 5). The number of fibres released into the air from ACS is likely to be influenced by range of site-specific factors (eg RIVM, 2003, and Addison et al, 1988), some of which are summarised in Table 9.1.

Table 9.1 Factors affecting the release of airborne fibres from asbestos-containing soils

Characteristics of the asbestos or ACM

�� concentration of asbestos in soil�� degree of heterogeneity�� depth to ACS in relation to (final) ground level�� volume or surface area of ACS�� type(s) of asbestos present�� type(s) and condition of ACMs�� extent of bonding/friability�� weathering, degradation or physical deterioration�� fraction of free respirable fibres�� shape of the asbestos fibres.

Characteristics of the soil

�� soil type including particle size distribution�� (micro) relief of soil surface�� soil moisture content�� presence of surface vegetation�� presence of hard landscaping or cover.

Weather influences

�� air humidity�� precipitation�� temperature �� ground freezing�� wind speed and direction.

Land use/soil-disturbing activities

�� behaviour of receptor(s)�� distance of receptor(s) from the source of asbestos�� type(s) of activities�� duration and frequency of activities�� any dust mitigation measures employed.

9.1 ReleASe Of WInd-blOWn fIbReSThe generation of wind-blown dust from soil has been relatively well studied (Environment Agency 2009), but far less data is available concerning the release of asbestos fibres from contaminated soils.

Wind action can release fine respirable dust particles (RIVM, 2003) and asbestos fibres from the soil surface when dry even when coarser soil fractions (eg silts, sands and gravels) are unlikely to become airborne. The main factors affecting this release are weather (eg wind speed, wind direction, rainfall, soil moisture) and vegetation, both of which can vary with time.

AimThis chapter summarises current knowledge regarding the factors influencing the release of inhalable asbestos fibres from ACSs and made ground. Consideration of these factors will be needed when assessing risks, either from acute exposures under CAR etc or chronic exposures under Part 2A or planning regimes.


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However, where wet soil migrates (eg on feet, animals, equipment or machinery) onto hard standing, such as paths, pavements, roads, patios etc it can rapidly dry out and form dust at any time of the year, even under overcast condition. The liberation of airborne fibres from such dusts could result in a greater exposure than would be expected from the soil alone.

In urban areas, children playing, cycle tracks etc all damage the soil surface and vegetation and increase the likelihood of wind-blown asbestos being released. Where they are present, burrowing animals (eg moles, badgers, foxes or rabbits) can also bring up asbestos previously buried at a significant depth and expose it at the soil surface.

In rural areas, the probability of asbestos being present is much less but is sometimes encountered. Grazing animals (eg cattle, sheep, horses) and farming activities (eg harrowing, ploughing, harvesting) can disturb any asbestos present near the surface, increasing airborne fibre concentrations.

In most situations, physical disturbance of ACSs are likely to result in larger exposures than wind-blown fibres, particularly if only bound asbestos materials are present. However, where friable materials and free asbestos fibres are present in soils, airborne concentrations that are of concern could be generated by areas of bare soil during dry conditions. In such cases it may be necessary assess the risks to those living or working downwind, although such risks are likely to decline rapidly at increasing distances from the source.

9.2 ReleASe Of fIbReS by phySICAl dIStuRbAnCeThere is little published data relating to the release of fibres from ACSs following physical disturbances (eg digging, excavation, rotavating, vehicle movements, cycling or children playing) either in the UK or elsewhere. However, it is clear that risk mainly relate to dry soils and dusts (<10 per cent moisture).

One of the few empirical studies was conducted by Addison et al (1988) at the Institute of Occupational Medicine (IOM). In laboratory simulations they studied the release of three types of asbestos fibre (chrysotile, amosite and crocidolite) from three spiked soils (sandy, intermediate and clay) using mechanical dust generators. They prepared soil-asbestos mixtures for each form of asbestos and each soil type at asbestos concentrations of one per cent, 0.1 per cent, 0.01 per cent and 0.001 per cent mass concentration using blenders and food processors. For each of the 36 resulting mixtures, airborne fibre concentrations were measured relative to the respirable soil dust concentrations generated. The results were discussed in relation to the prevailing occupational exposure limit for respirable nuisance dust, 5 mg/m3. The effects on fibre release of different levels of moisture content in the soils (weight water to weight dry soil percentages) were also studied.

Addison et al (1988) remains one of the most relevant studies regarding fibre release from ACSs and showed that:

�� for a given combination of soil type, asbestos mineral and constant soil dust in air concentration, the concentrations of asbestos in air were roughly proportional to the percentage of asbestos in the soil

�� for a given asbestos type, sandy soil released more asbestos fibre than intermediate soil than clay

�� for a given soil type, crocidolite was released more readily than amosite which, in turn, was released more readily than chrysotile

�� at 0 per cent moisture in the soil, concentrations of airborne asbestos exceeding the occupational control limits (>0.1 fibres/ml) could be generated from soils containing as little as 0.001 per cent while respirable dust concentrations were at or below the prevailing occupational exposure limit of 5mg/m3

�� the release of airborne asbestos was strongly influenced by soil moisture content (see Section 9.7.2). The addition of five per cent moisture reduced airborne asbestos by 80 to 95 per cent and no airborne fibres were detected above 15 per cent moisture

�� at soil concentrations below 0.01 per cent asbestos, SEM showed that non-asbestos particles accounted for a substantial proportion of the fibre-like structures in air samples. However, many



of these fibres would probably not have been counted by PCOM and so should not have unduly affected the overall results.

These finding (particularly the elevated airborne asbestos concentrations) led directly to the updated ICRCL (1990) guidance on asbestos in soil (see Section 7.1). However, the applicability of the Addison et al (1988) to made ground, bound ACMs or soils not containing uniformly distributed asbestos is rarely evaluated by practitioners.

Subsequently, a large amount of work has been conducted in the Netherlands as part of an initiative to derive policy on ACSs (RIVM, 2003, and Swartjes and Tromp 2008). More than 1000 measurements of airborne fibre concentrations were collated representing either “worst case simulation experiments” or “field experiments from daily practice activities”. Data is reported for both ‘friable’ and ‘bound’ ACMs (such as asbestos cement). This data is summarised in Figure 9.1.

The main conclusions drawn from the data were:

�� no airborne fibres were detected in field measurements from soils containing bound asbestos at concentrations up to one per cent (total of 350 measurements)

�� for friable asbestos, higher soil concentrations generate higher airborne fibre concentrations. In field trials, mean airborne fibre concentrations ranged from around 0.0001 f/ml at 0.01 per cent up to around 0.05 f/ml at over one per cent (total of 200 measurements)

�� the variability in the data is high. For example, the highest airborne concentration measured at 0.01 per cent exceeds the lowest measurement at one per cent in soil

�� in general, ‘worst case’ laboratory simulations predict higher airborne concentrations than are seen in field measurements.

The data presented in Figure 9.1 represents a substantial body of information. However, full details of the laboratory and field measurement methodologies are not provided in the available reports (the underlying study is available only in Dutch). So, it is difficult to gauge the statistical significance of the results because it is not clear how many measurements each data point in Figure 9.1 represents. In terms of the field measurements, RIVM (2003) acknowledges that “measurement conditions were frequently not well defined and the soil was often (made) damp”, implying that standard health and safety procedures, such as damping down, may have been applied and that weather conditions may also have affected the measurements. Also, the concentrations of asbestos in soil cited for the field measurements will be less precise than for laboratory simulations, due to sampling and analytical uncertainties and the heterogeneity of asbestos in soils on such sites. The data in Figure 9.1, while informative, should be interpreted with caution.

Figure 9.1 suggests a broadly similar trend between airborne asbestos and ‘friable’ asbestos in soil as indicated by Addison et al (1988). The variation in the field measurements is not surprising given the many variables that would affect such measurements. A difference in airborne concentrations measured in the laboratory and in the field is not surprising because the dilution rate is controlled in laboratory simulations. The fact that the trends in the data are nearly parallel means that the simulations are consistent with the field measurements. Unlike Addison et al (1988) however, the Dutch reports did not give the concentrations of soil dust in air, which can act as a valuable comparator for airborne fibre concentrations.

noteLaboratory simulations involved “using a wind blower with dry soil and loose asbestos fibres” and the field measurements were described as “driving on contaminated roads and digging, dumping and sifting of humid soil with a mixture of friable and bound asbestos” (Swartjes and Tromp, 2008).

noteRIVM (2003) and Swartjes and Tromp (2008) evaluated the air concentrations in terms of Dutch air standards for asbestos (ie negligible risk and maximum permissible levels). The applicability of these assessment limits to the UK is discussed in Section 7.3.


CIRIA, C73366

Nevertheless the Dutch study, and those of naturally-occurring asbestos carried out by US EPA in the EI Dorado Hills and Clear Creek areas of California, show that physical disturbance of ACSs can generate significant levels of airborne asbestos fibres.

Figure 9.1 Average airborne asbestos concentrations from simulated and field measurements (after Swartjes and Tromp, 2008)

9.3 COnSIdeRAtIOn Of depthIn the absence of significant physical disturbance, exposure to airborne asbestos fibres from soil will be from friable materials or asbestos fibres present at, or very close to, the soil surface (ie the soil-air interface). Materials that have been buried or are below the soil surface will pose lower (or less immediate) risks as these materials cannot release airborne fibres unless brought to the surface by physical disturbance.

Consequently, soil risk assessments for buried asbestos primarily need to consider the likelihood that such materials may reach the surface due to the action of burrowing animals or human activities. The latter includes both disturbances during any redevelopment (eg earthworks or construction activities, remediation and earthworks) and permitted activities under the current planning consent. At residential sites this may include children playing, gardening, building maintenance and improvements, landscaping and tree planting.

9.4 COnSIdeRAtIOn Of lAnd uSe And ACtIvItIeSActivities that disturb dry soils generate dust and disturbing ACSs is also likely to liberate airborne asbestos fibres. However, the main source of published information on the airborne asbestos levels generated from ACSs (RIVM, 2003, and Swartjes and Tromp 2008) appear to relate solely to construction activities and provide little information on what, if any, control measures were in place by different types of activities or land uses.

Box 9.1 Vermiculite mining and natural contamination in Libby, Montana

Key

Measurements (symbols) in fibres/m3air and 95 per cent confidence intervals (hyphens), from worst case simulation experiments (�), from field measurements with friable () and bound () asbestos, as a function of asbestos concentration in soil. The sloping lines are assumed to represent the trends in the simulated and field data.

There is widespread asbestos contamination in Libby, Montana, associated with vermiculite mining and natural ground contamination. Weis (2001) reported an asbestos in air concentration of 0.066 fibre/ml in personal sampling during rototilling of soils in Libby. The ground being worked was reported as contaminated but the level of contamination and moisture content are not clear. This work demonstrates a clear link between asbestos in soil and exposure to significant concentrations of airborne asbestos fibres during soil disturbance. There is excess mesothelioma in Libby, eg Sullivan (2007) and Antao et al (2012). Asbestos exposures and risks are higher for those occupationally than those only environmentally exposed. Asbestos-related radiographic abnormalities (which have a shorter latency than mesothelioma) have also been observed in the Libby population. Environmental exposures and other non-occupational risk factors were important predictors of these asbestos-related radiographic abnormalities.



Redevelopment and construction activities (including earthworks, remediation and utilities work) are likely to involve significant soil disturbance. Consequently, the airborne fibre concentrations are likely to exceed those typically encountered after development. Effective dust control measures can be implemented during such works, but these measures are unlikely to be appropriate or practical to control any fibre release associated with the post-development land use. The assessment and control of such airborne fibres under CAR is described in Section 8.1.3.

The long-term environmental exposure of residents, workers, neighbours or the general public to airborne asbestos fibres following the completion of any development or remedial activities will depend on the nature of the land use and likely soil disturbing activities that may occur within the existing planning permission. For example, there is no legal impediment to home owners removing patios or other hard landscaping from their gardens or even breaching capping layers while installing ponds or planting trees etc. The extent of any such exposures will heavily depend on the frequency, duration, and nature of the soil disturbance and the distance of the receptor from such activities. The calculation of potential exposures is discussed in detail in Chapter 13.

Outdoor activities at allotments, gardens and parks, such as manual gardening activities or children playing, may result in the release of airborne fibres. The movement of vehicles or bicycles on contaminated soils, tracks or paths etc could also release airborne fibres. Where asbestos fibres may be ‘tracked back’ indoors, exposures may also be significant, particularly for residential land uses.

Estate management activities at residential, commercial or public buildings may also have the potential to result in occupational asbestos exposures to gardeners and estates staff.

Airborne fibres will predominantly be released only from exposed soil. Any form of hard standing (road, pavement, paving, car park etc) is likely to prevent the release of airborne fibres from the soils directly beneath it. However, such surfaces will also provide an area upon which asbestos fibres contained in mud and surface runoff can dry out and so are liable to wind-blown disturbance or disturbance by moving vehicles.

The release of airborne fibres will also be influenced by the presence and types of surface vegetation. Fibres will be more easily released from bare soil than from lawns or heavily planted areas.

Figure 9.2 Showing the dust raised during dry weather by lorry movements on a track partly surfaces with crushed asbestos cement (a), and a close-up of the asbestos cement fragments at the track surface (b). For scale, the sample vial is roughly 10 cm in height

9.5 COnSIdeRAtIOn Of ASbeStOS typeAddison et al (1988) suggests that the three asbestos types studied (ie chrysotile, amosite and crocidolite) generated slightly different airborne fibre concentrations. Amphibole types appeared to generate


CIRIA, C73368

higher airborne concentrations than chrysotile. This is consistent with HSE findings that removal of asbestos lagging resulted in higher concentrations for lagging containing crocidolite. The, comparatively small, differences between asbestos types are shown in Figure 9.3. The relatively constant conditions in laboratory tests enable the influence of asbestos type to be observed.

Figure 9.3 Indicating the effect of asbestos type on airborne fibre (from Table 3.1, Addison et al, 1988)

9.6 COnSIdeRAtIOn Of dIffeRent typeS Of ACmWhere ACMs (rather than free fibres) are present in soils, the asbestos fibres may become dispersed into the air either after being released from the matrix into the soil and/or by the ACM being disturbed when it is on the surface. The rate of release of asbestos fibres for different types of ACM will depend on factors such as:

�� the friability of the ACM (ie the degree to which asbestos fibres are bound within a matrix)

�� the degree of weathering or degradation

�� physical wear or breakdown (eg by traffic)

�� the asbestos concentration within the ACM. Some ACM products contained 100 per cent asbestos (such as asbestos quilt insulation etc) while others contained less than 10 per cent asbestos bound in a cohesive matrix, such as linoleum (eg tiles), bitumen (eg felts) or asbestos cement.

Asbestos fibres disperse very slowly in undisturbed soils, so the potential hazard may increase over time as more fibres are released. However, the timescales involved will vary considerable depending on the type of ACM and weathering/degradation mechanisms (see Section 9.6.1). There is almost no data on the rates at which different ACM weather and degrade in the soil environment. Friable materials (eg AIB, lagging) might be expected to deteriorate relatively quickly (years) while more tightly bound materials (eg asbestos cement, bitumen products) are likely to deteriorate very slowly over decades or longer (RIVM, 2003).

9 .6 .1 Friability of ACMsFriable ACMs release fibres more easily (and probably at a higher rate) than tightly bound ACMs (Figure 9.4), resulting in more free fibres in soil and potentially higher concentrations of airborne fibres too (Burdett, undated, RIVM, 2003, Swartjes and Tromp, 2008). A range of ACMs are presented in order of friability in Appendix A1.

note:

For each type of asbestos, a combined mean for three soil types (sand, intermediate and clay) and four concentrations (1 to 0.001 per cent w/w) is presented ± 99 per cent confidence interval (n=12). In all cases, airborne fibre counts have been normalised relative to that observed for crocidolite (confidence interval =0).



However, work in the Netherlands (RIVM, 2003, and Swartjes and Tromp, 2008) suggested that almost no fibres were released from bound asbestos cement, with all but one of 350 field measurements producing no detectable increase in airborne fibres even at soil concentrations in excess of 10 000 mg/kg (>one per cent asbestos). The only exception related to measurements of a road surfaced with pure asbestos cement (>10 per cent asbestos), which was reported as being significantly degraded/broken. Similarly, tests at the HSL found detectable levels of free fibre were not generated from intact asbestos cement but were from asbestos cement fragments (Figure 9.5). This is believed to be due to the increased surface area and physical degradation of the cement matrix at the edges of each fragment.

notes

Estimates are based on soil analyses carried out by TNO over a 10-year period.Note they had a specific definition of what was meant by ‘respirable’ fibres.

Figure 9.4 ‘Respirable’ asbestos fibres fraction for amphibole and chrysotile asbestos according to bonding (after RIVM, 2003)

notes

AC = asbestos cementAIB = Asbestos insulation board (after Burdett undated).

Figure 9.5 Relative release of PCM fibres in dustiness tests for different types of asbestos-containing materials


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9 .6 .2 Weathering and degradationPhysical and chemical degradation of ACMs due to mechanical wear, natural weathering and chemical leaching will promote primary release of fibres into the soil.

Although, the HSE have estimated rates of fibre emission for activities with asbestos cement products, AIB, and asbestos insulation above ground (eg HSE, 1983), there are only a few scientific studies regarding fibre emission from such materials in or on the ground (Jones et al, 2005, RIVM, 2003, and Swartjes and Tromp, 2008).

The extent to which bound asbestos materials (eg asbestos cement) will break down will vary with the types of activity on the site. Heavy vehicular trafficking is likely to generate smaller fragments and particles and cause primary release of some fibres. This was observed where roads and tracks have been surfaced with asbestos-cement wastes in Cambridgeshire (Jones et al, 2005) and the Netherlands (RIVM, 2003). For example, as part of an environmental risk assessment Jones et al (2005) measured airborne concentrations of up to 0.0007 f/ml (averaged over seven days and when there was little vehicular traffic, and LoQ of <0.00001 f/ml) at locations adjacent to six farm tracks and rights of way.

However, in the absence of such physical wear, the degradation rate of bound materials may be negligible. RIVM (2003) reported that “the majority of asbestos cement products only show a slight amount of weathering after decades”. This is supported by the practical experience of the authors.

The uncertainties over weathering and degradation rates for buried ACMs (particularly asbestos cement) and the resulting fibre release rates are a significant limitation of current understanding of the risks posed by such materials. The need for further studies of fibres release rates for bound asbestos in soils was highlighted by Swartjes and Tromp (2008).

9.7 COnSIdeRAtIOn Of SOIl ChARACteRIStICS

9.7.1 InfluenceofsoiltypeThe engineering geological properties of a soil can have a major influence on the release of asbestos fibres. Such properties include moisture content, total and water filled porosity, particle size distribution (PSD), density, cohesion and surface cover.

Addison et al (1988) studied the release of airborne asbestos from three natural soils, termed sandy, intermediate and clay (partial descriptions are presented in the report). All particles coarser than 3mm were removed before experimentation and the soils were mixed in blenders and food processors. They showed that the three soil types generally produced different airborne fibre concentrations, with the sandy soil generally producing higher concentrations than the clay soil (Figure 9.6). It was suggested that this represented, in part, an inhibitory or competitive effect of clay particles, which reduces the effective release of asbestos fibres from fine grained soils (Addison et al, 1988). Similar results have been reported by others (RIVM, 2003).

For each soil type, a combined mean for chrysotile, amosite or crocidolite at three concentrations (1 to 0.01 per cent w/w) is presented ± 99 per cent confidence interval (n=9). Data for 0.001 per cent asbestos was excluded as it was too susceptible to random variation in fibre counts. In all cases, airborne fibre counts have been normalised relative to that observed for sand (confidence interval = 0).

However, the three soils studied by Addison et al (1998) are not necessarily representative of made ground materials such as those identified by Rosenbaum et al (2003). If made ground materials have a larger particle size than the sands used by Addison et al, it is possible that they would allow greater fibre release than observed in the laboratory tests. So, the tests could be extended to be more relevant to made ground found at most post-industrial brownfield sites. It is not clear if variation in other soil properties (eg organic matter content) would have any effect on airborne fibre concentrations.



Figure 9.6 Indicating the effect of soil type on airborne fibre release (from Table 3.1, Addison et al, 1988)

9.7.2 InfluenceofsoilmoisturecontentThe moisture content of the soil is one of the most important factors dictating the emission of airborne asbestos fibres from soil. Minor increases in moisture content significantly reduce the release of fibres (Figure 9.7).

Figure 9.7 Indicating the potential reductions in airborne fibre count with increasing soil moisture (from Table 4.3, Addison et al, 1988)

For each moisture level, a combined mean for chrysotile, amosite or crocidolite at four concentrations (1 to 0.001 per cent w/w) and in three different soil types is presented ± 99 per cent confidence interval (n~36). In all cases, airborne fibre counts have been normalised relative to that observed at 0 per cent moisture. A hypothetical trend in the means is presented for illustration only

Addison et al (1988) investigated the effect of soil moisture (between 0 and 50 per cent w/w) on airborne fibre release and showed that the addition of 10 per cent water (to dry soil) decreased the release of asbestos to air by a factor of between 2 and 10, depending on the mixture tested. Figure 9.7 shows the


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average results of Addison et al (1988) normalised to fibre release from dry soil. Similar findings were reported from the Netherlands (RIVM, 2003).

It should be noted that the moisture contents reported by Addison et al (1988) are based on the addition of water to a soil containing zero per cent moisture (ie dried at 50°C until they were of stable weight). This differs from current geotechnical methods (eg BS 1377-1 1990) for determining soil moisture content. Soil moistures derived by such geotechnical tests should not be compared directly with the Addison data.

In the UK, most soils, even after long dry periods, are likely to have about five per cent moisture apart from extreme or very localised situations, both of which are likely to represent a relatively small proportion of time or space on a site. It is the moisture content at the soil surface that dictates the release of airborne fibres, which will vary relatively rapidly based on local weather conditions. The desiccation of soil-derived dusts on paths, drives, roads and patios etc should also be considered.

This observation is the basis for ‘damping down’ as a mitigation measure to control occupational exposures to airborne asbestos. The application of water (eg using hoses, sprays or mists) can significantly, if not completely, suppress the release of airborne dust and asbestos during the investigation, or remediation of ACSs, or general earthworks that disturb such materials.

Summary

�� the primary release of asbestos fibres in to the soil from buried ACMs is determined by the type(s) of ACM present, the asbestos content, the type of matrix material and the durability and friability of the ACM. Soil conditions and physical disturbance will also have an impact

�� increasing amounts of free fibres are likely to be released into the soil from ACMs over time – all ACMs will deteriorate/degrade eventually but the processes are poorly constrained

�� firmly bound materials (eg asbestos cement) may release few fibres when in good condition and may take a very long time to degrade, if undisturbed

�� friable materials (eg AIB and lagging) are likely to release fibres more easily and deteriorate relatively rapidly within soils

�� the secondary release of asbestos fibres from the soil into the air can occur via wind-blown disturbance or physical disturbance either during site development (eg construction, remediation or earthworks) or during site use (eg gardening and children playing)

�� the ability for fibres to be released to air is influenced by many factors including asbestos type, ACM type, depth and concentration in soil, soil type, and soil moisture content

�� soil moisture content also has a significant effect. The addition of five per cent moisture to dry soil reduced airborne fibre release (in laboratory tests) by 80 to 95 per cent, and no airborne fibre were detected above 40 per cent soil moisture content

�� the level of any exposure to a receptor will depend on the rate that respirable fibres are released into the air, exposure duration and frequency, distance to the receptor and climatic factors (precipitation, temperature, wind direction, wind speed and turbulence etc). Estimating human exposures is discussed in detail in Chapter 13.



part 2managing the risks of asbestos in soil and made ground


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10 preliminary risk assessment and developing the conceptual site model

10.1 GeneRAl pRInCIpleS Of COnCeptuAl SIte mOdellInG

Having established the legal context, a preliminary risk assessment (PRA) is carried out by “develop[ing] an initial conceptual model of the site and establish[ing] whether or not there are potentially unacceptable risks” (Environment Agency, 2004). Similar provisions are contained in BS 10175:2011+A1:2013. The potential for ACSs to be present should be considered during the PRA at all sites unless adequate justification for not doing so can be documented (eg there are records of the pre-demolition survey available and records of any subsequent asbestos removal and disposal). This is in-line with the information in the DoE’s industry profiles and the requirements of CAR. Some industries have an elevated likelihood of asbestos being present.

A thorough and robust PRA should include both a desk study and a site reconnaissance survey to explore the likelihood that ACSs are present. Where there is a reasonable possibility that asbestos may be present, it should be clearly reported in the PRA, together with indications of the likely form, type and location(s) etc, and included in the initial CSM. The CSM should summarise the site, its history, all potential contaminant linkages and the major sources of uncertainty. It is a central component of the investigation and management of land contamination (Environment Agency, 2004, and Nathanail et al, 2007).

The development of a robust CSM is particularly important in the case of asbestos in soils and made ground, as exposure has particularly serious health consequences and its distribution is usually highly heterogeneous in comparison to other commonly encountered soil contaminants. Without an effective CSM it is not possible to design an appropriate field investigation to adequately and robustly characterise the potential risks posed by ACSs.

10.2 pOtentIAl SOuRCeS: SCOpe And COnSIdeRAtIOnSIndustries, structures and features that were particularly significant sources of asbestos in soils have been identified by ICRCL (1990) and Western Australia (2009a). These are summarised in Table 10.1. Also, asbestos is cited as a possible contaminant of concern in all 48 industry profiles published by the Department of the Environment in 1995 to 1996. Steeds et al (1996) also identifies 12 industries that have an elevated likelihood of asbestos, and asbestos is cited in several ‘special site’ guidance documents.

There are three main classes of sites where ACSs may well be present:

�� manufacturing sites where asbestos was handled and/or ACMs or products were manufactured

�� waste management, disposal and processing sites (such as scrap yards and landfills)

�� demolition sites where buildings (industrial and residential), and other structures, plant or services containing asbestos or ACMs, have been demolished.

AimThis chapter summarises the considerations needed to construct a conceptual site model (CSM) based on the desk study and site reconnaissance. The CSM underpins the soil risk assessment and should reflect the nature, potential distribution and likely behaviour of ACMs that may be present. It highlights issues and sources of information that are specific to ACSs that are not normally considered for other soil contaminants.



However, there is an increasingly common fourth class of sites where ACSs or aggregates have been imported during current or previous redevelopment activities. The quantities of asbestos identified in these cases may be low but its presence can still be problematic given the current uncertainties in the risk assessment process.

Table 10.1 Industries as particularly significant sources of asbestos in soils

Railway land, especially large workshops, depots and siding areas but also including track ballast etc

Heavy engineering sites, for example ship builders, ship repairers and ship breakers

Old waste disposal sites, particularly those pre-dating current legislation and controls

Scrap yards

Power stations, including boiler houses at industrial sites

Pre-1980s buildings and structures damaged by fire or storm

Land with fill or foundation material of unknown composition

Sites with buildings containing ACM or asbestos insulation materials (eg asbestos roofing, sheds, garages, water tanks and boilers)

Sites where pre-1980s buildings and structures were improperly demolished or renovated, or where relevant documentation is lacking

Disused services with ACM piping

10 .2 .1 Manufacturing sitesThe limited numbers of sites in the UK where asbestos was handled and/or ACMs or products were manufactured are highlighted in “The Industry Profile on Former Asbestos Manufacturing Works” (DOE, 1995). Both the potential for diffuse contamination in surface soils and historical waste disposal practices at such sites should be considered.

Waste asbestos that could not be reused (eg fines from dust extraction systems) was often dumped or buried on-site or at other sites (which may be some distance from the original factory). Later experience suggests that off-site exportation was particularly prevalent in the case of asbestos cement wastes. Such wastes were regarded as useful for “making up ground and as foundation material for new buildings, car parks etc” (DOE, 1995). Indeed there is now extensive experience indicating that such wastes were given, or even sold, as aggregate to local third parties (eg landowners, developers and farmers etc). As a result, such materials may be found some distance from the original asbestos factory and have resulted in ACSs across a broad area. For example, the use of asbestos cement as hard-core surfacing for roads and tracks several miles from the original manufacturing sites has been documented in Cambridgeshire and in the Netherlands. NHBC (pers comm) have also reported an increase in reports of asbestos cement infill materials being encountered during the redevelopment of sites close to former asbestos cement factories.

In addition, the management of wastes and demolition arisings following the closure of asbestos manufacturing facilities should also be established, particularly if this occurred before legislation controlling such activities came into effect circa 2000.

Finally, consideration should also be given to the potential deposition of airborne fibres from nearby manufacturing facilities. In at least one case in the UK, atmospheric fibre emissions from an asbestos factory had apparently affected houses up to 1600 m away (Cherrie et al, 2001, and Cherrie et al, 2005). In these studies asbestos was found inside homes but no data was collected on whether detectable amounts of asbestos were present in the surrounding soil.

10 .2 .2 Waste management sitesAsbestos should be anticipated at any sites previously engaged with waste management, disposal or


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processing, particularly those pre-dating current legislation and controls. A wide range of materials, potentially including demolition and other wastes containing asbestos could have been disposed of at such sites. Asbestos may be distributed throughout the waste mass or be present as isolated deposits within it, depending on the nature and practices at that site.

As well as commercial facilities for municipal and commercial wastes, many large industrial sites would have operated informal landfills. Increasingly stringent legal controls of asbestos during the 20th century often led to ACM being stripped from operational areas and being disposed in these landfills. Until controls were fully implemented, all forms of asbestos may have been stripped or dumped on such sites and so may be present near the surface.

10 .2 .3 Demolition sitesAlmost all brownfield sites have a history of demolition, reconstruction and filling/raising the ground. So demolition arisings from on-site or off-site sources may be encountered on most sites. There is a corresponding potential for ACM and fibres to be present in such made ground.

Unless completely removed before demolition, buildings, structures and services still contain asbestos, ACMs or asbestos-containing products and equipment (eg gaskets, rope, fire blankets) when demolished. This applies to most former industrial sites but asbestos and ACMs were also widely used in a diversity of domestic, commercial or public building. Many such buildings built before the 1980s may contain significant amounts of ACMs

Any site where buildings have been demolished may potentially be affected by ACSs (Watson, 2010), but this does not mean that asbestos is present in large quantities or that the risks to human health are unacceptable at all such sites. Due to improved demolition practices, the risk of encountering ACSs following the demolition of buildings built on greenfield sites after 2000 (or demolition of structures that have had a full asbestos survey confirming a low likelihood of ACM) is quite low. Where buildings were built on brownfield sites, there remains a significant possibility that demolition of the foundations will expose previous contamination.

10 .2 .4 Sites affected by imported materialsAn emerging class of asbestos-containing sites are those affected by imported materials (eg soils and aggregates) derived from, or contaminated by, demolition arisings. There are several cases where soils containing low levels of asbestos are likely to have arisen from ‘topsoil’ imported in the 1960s, 1970s, 1980s and 1990s, and that detectable levels of asbestos are relatively common in modern recycled aggregates.

Low levels of asbestos fibres may also be encountered within sediments and dredgings from docks, rivers and canals, particularly those in urban environments. Such dredgings have been historically disposed of on surrounding land or to raise nearby development sites.

So unless its exclusion can be justified, the PRA should also consider the possibility for ACSs being present where:

�� previous activities are known to have included the importation of such materials (particularly if large volumes were involved)

�� the source of such materials is considered high risk (eg in the vicinity of asbestos factories, railway sidings, or major industrial sites)

�� such materials are exposed at the surface.

10 .2 .5 Mode of deposition and proposed earthworksAsbestos is often encountered as discrete deposits, or caches, such as those relating to on-site disposal of stripped asbestos, waste tips or ACSs capped during earlier risk management activities. Such discrete and localised asbestos caches may be simpler to characterise and, if necessary, remediate than ACSs



that are dispersed and heterogeneous (eg demolition wastes, imported topsoil and airborne deposition). However, the inadvertent spread of such caches during development can lead to post-development risks and liabilities. So, it is important that the PRA also addresses the possible presence of such discrete deposits of asbestos at the site.

Because asbestos does not diffuse through soils nor spread through soils by dissolution in water (unlike liquid or soluble chemicals), the presence of asbestos is likely to be much more variable in the soil or made ground. Where the history of the site indicates that made ground has been through processing, then there may an expectation that the heterogeneity will be reduced – but any contamination problem may have become more widespread.

As with all contaminants, but particularly for asbestos, the PRA should also take account of any anticipated earthworks, proposed site layout and final levels, where available. Asbestos caches buried at depth may be exposed during subsequent ‘cut and fill’ operations or the excavations of footings and service corridors etc. Competent management of such caches during redevelopment is essential to minimise future risks.

Likewise, the nature of surfacing across the site should be considered at an early stage where ACSs may remain on-site post-development. Careful site layout and design has the potential to deliver substantial cost savings while minimising the potential exposure of workers, subsequent site occupants and the public.

To avoid potential problems and maximise potential cost-savings, significant collaboration will be required between all parties (owners, developers and consultants) to communicate the proposed layouts, earthworks and changes to site levels at an early stage. This would be in compliance with duties imposed on all employers under CAR to identify and minimise asbestos exposures and any potential spread of asbestos. The exposure and redistribution of ACSs should also be considered where such materials are reused on-site under the waste code of practice by CL:AIRE (2011).

10.3 pOtentIAl expOSuRe pAthWAyS: SCOpe And COnSIdeRAtIOnS

Asbestos does not form vapours or occur as a gas and the risks from ingestion are generally considered to be negligible, so asbestos risk is considered in terms of the inhalation of fibres. So the only pathways that normally need to be addressed for ACSs involve outdoor and indoor inhalation.

10 .3 .1 Exposure via outdoor inhalationMeasurements have shown that outdoor air in the UK contains background concentrations of asbestos fibres (see Section 6.3). Background concentrations were measured in the 1970s and 1980s and may now be lower due to decreased use of asbestos in the UK. As other sources become rarer and better controlled, the potential exposure of residents, workers or the public in the vicinity of affected sites may become more prominent.

The limited empirical evidence concerning the release of airborne fibres from ACSs are discussed in Chapter 9. However, there is little, if any, relevant data (ie at sufficiently low detection limits and monitored over appropriate timescales and under appropriate conditions) that can demonstrate whether airborne fibres are (or are not) not released from soils in the UK at concentrations above ambient background concentrations. Field measurements from the Netherlands (see Section 9.2) demonstrate that disturbing friable asbestos in soils can generate airborne concentrations well above expected background concentrations, and that greater concentrations of friable ACMs in soil result in higher concentrations of asbestos fibres in air. Only at concentrations well above one per cent were airborne fibres detected from bound ACMs. However, in at least one case in the UK, measurements have demonstrated that the presence of bound ACMs on tracks does give rise to measureable asbestos in air when the ACMs are subjected to crushing by vehicles (Box 13.1).


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Even where friable ACM or free asbestos fibres are present in soil, concentrations of airborne fibres in most situations are likely to be low. However, unacceptable risks may still occur during dry weather if soil-disturbing activities (such as ground works, maintenance activities), or recreational activities (such as gardening or children playing) result in infrequent exposures to elevated fibre concentrations. This is particularly true if amphibole asbestos is present.

The estimation of potential outdoor exposures is discussed in detail in Chapter 13.

10 .3 .2 Exposure via indoor inhalationContaminated land guidance in the UK, such as by Jeffries and Martin (2009), includes consideration of soil contamination ‘tracked back’ into the home/workplace. The extent to which asbestos fibres in soil are transported to the indoor environment on shoes and clothing etc has not been well studied. However, it has been speculated that once inside the home/workplace asbestos fibres may accumulate and be constantly re-suspended by activities such as vacuuming, cleaning, dusting, children playing or simply moving about (RIVM, 2004).

The potential risks via this indoor dust inhalation pathway should not be assumed to be minimal, particularly in residential scenarios. RIVM (2004) noted that children spend longer periods indoors than adults, are shorter than adults and have a greater propensity to disturb dust than adults. Children may also be more susceptible to asbestos than adults (WATCH, 2011). All these factors should be considered when assessing risks in a residential scenario.

The experience of the authors suggests that ACS generally do not result in detectable levels of asbestos fibres inside adjacent buildings. However, it should be noted that most of these sites have bound asbestos in soils with limited amounts of free fibres, and that under such circumstances, the track back of asbestos fibres would be expected to be low. Tracking back of asbestos was investigated at three residential properties with gardens containing an average of between 0.03 per cent and 0.17 per cent amosite asbestos in the form of loose insulation in the surface layers (Robertson et al, 2011). One garden was bare earth and small children lived in the property. In all properties, tracking back was found to be only a minor cause of asbestos exposure. In a review, RIVM (2004) suggested that a significant impact on indoor air may be expected where soil adjacent to properties contained more than 100mg/kg of friable asbestos. However, there is considerable uncertainty in that estimate.

The relative importance of indoor and outdoor exposures is likely to depend on the site-specific situation. Unsurprisingly, markedly different approaches to soil risk assessment have been adopted at various sites – some focusing on characterising long-term low level indoor exposure and others on outdoor exposures due to occasional disturbance of dry and dusty soils. Published information (RIVM, 2004) suggests that, at the very least, indoor inhalation of fibres should be considered (in addition to outdoor exposure) where soils contain greater than 0.01 per cent asbestos.

The estimation of potential indoor exposures is discussed in detail in Chapter 13.

10.3.3 WaterbornefibresIn rare instances, it may be necessary to consider the migration of asbestos fibres via surface runoff and surface waters, if fibres could be deposited and exposed in populated areas (eg during hot periods or low flow events). For example, runoff may be carried by surface water drains or sustainable urban drainage systems that pass through a residential estate. Or, as another example, erosion of buried asbestos deposits by a nearby stream may result in substantial amounts of asbestos fibres being deposited downstream.

Sediments in urban watercourses may commonly contain low levels of asbestos fibres. Care should be taken in disposing of dredgings etc as, once dry, airborne fibres may be released from such materials.

Exposure via ingestion of fibres in potable water supplies is not considered a significant risk. Asbestos cement was widely used for water supplies and asbestos has been used in wine filtration.



10.4 pOtentIAl ReCeptORS: SCOpe And COnSIdeRAtIOnS

10 .4 .1 The receptors to be considered for asbestosThe only receptors of interest with respect to asbestos in soils and made ground are humans exposed via inhalation. This may include current and future residents/occupants/employees, neighbours, utilities workers and the public (including trespassers). Risks may also exist to workers during any investigation, remediation and construction works involving ACSs. The assessment and control of such occupational risks should be in accordance with CAR 2012 and other relevant health and safety legislation and guidance.

10 .4 .2 Receptors not relevant for asbestosUnlike many other contaminants, asbestos does not pose risks to buildings and services (except to the human users of such structures) and is unlikely to pose any risks to the water environment.

There is no evidence that asbestos poses a risk to plants or invertebrates (which cannot inhale asbestos fibres). Even though exposure of vertebrates, particularly burrowing animals (eg rabbits, foxes, badgers) may occur, it is unlikely to lead to mortality or to any impairment of ecological function. At present there are no scientific reports of animal mortality or ecosystem effect, even in the vicinity of asbestos mines and areas of NOA. Also, as the ingestion of asbestos fibres poses negligible risks, there should be no concerns even where potentially exposed domestic livestock or game species will be consumed by the public.

10.5 pRelImInARy RISK ASSeSSment (pRA)General guidance on conducting a PRA is contained in BS 10175:2011+A1:2013 and CLR11 (Environment Agency, 2004).

The PRA should involve the collection and review of documentary evidence, and a site reconnaissance survey, in order to record possible contaminant linkages within the CSM (Environment Agency, 2004). Information is also need to inform decisions regarding:

�� whether further field investigation is required

�� whether any special health and safety precautions are needed during any site inspection or investigation

�� the design of any field investigation and/or remedial measures.

Multiple potential contaminants will need to be considered at most redevelopment sites, of which one may be asbestos. Due to its unique nature and potential significance, asbestos should be considered within a specific section of any report but a separate report is not usually required. However, in some circumstances, this may assist in risk communication and risk management at the site.

The potential presence of ACSs does not alter the basic aims or approaches needed for a PRA. However, where asbestos is a potential contaminant of concern, the health and safety duties imposed by CAR 2012 may require additional diligence and resources in order to inform an appropriate health and safety risk assessment for subsequent site reconnaissance and any field investigation works. For example, demolition arisings are commonly encountered during field investigations, it is essential that the PRA identify this possibility before works start so that workers can be adequately protected. A ‘greenfield’ site does not necessarily mean that there is no asbestos.

A robust PRA is particularly important since the presence of asbestos can complicate and disrupt the redevelopment of brownfield sites. The disruption is greater if asbestos is only discovered after redevelopment has started and may be worse still if it is only discovered after the development is completed. “Asbestos contamination needs to be identified early and properly handled, to ensure subsequent disturbance and dissemination does not occur across the site and result in costly delays and extra investigative and remediation effort” (Western Australia, 2009a).


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10 .5 .1 Desk studyGuidance on conducting a desk study to identify the past uses of a site from maps and other documentary sources is provided in CLR3 (DoE, 1994), BS 10175:2011+A1:2013 and CLR11 (Environment Agency, 2004). With respect to asbestos in soils and made ground, the desk study should be sufficient to enable the identification of all potential sources (Section 10.2), pathways (Section 10.3) and receptors (Section 10.4) relevant to the site under consideration. It should also provide the basis for a suitable and sufficient health and safety risk assessment for a site reconnaissance visit.

A wide-range of documentary sources are normally considered during a desk study (see Table 3 of BS 10175:2011+A1:2013) but, where ACSs may be present, additional documentation may provide more specific information. This may involve contacting former landowners, operators or contractors to obtain details of:

�� the asbestos register (required for all commercial premises since 2004)

�� any asbestos surveys undertaken

�� any asbestos removal before demolition (including waste disposal records)

�� cross check asbestos removal records with asbestos registers, including any demolition survey data

�� any current or historical demolition activities (including waste disposal records or areas affected by demolition wastes)

�� any previous remediation relating to ACSs

�� any on-site waste disposal activities.

The Goad Fire insurance maps and plans (British Library, undated) are also worth consulting as obvious ACMs (eg asbestos cement roofing) were sometimes noted due to their fire-proofing potential.

Where historical on-site waste disposal or burial of asbestos materials is suspected, a thorough effort to identify the exact location of such activities should be made, including an inspection of relevant aerial photography to indicate details of the construction of historical structures, tip sites and other on-site activities. Where relevant individuals can be identified, interviews should also be used to obtain details of the use and disposal of ACMs at the site.

Full details should be documented as they may be required as defence evidence in any future legal cases relating to exposure to ACSs.

10 .5 .2 Site reconnaissanceA site reconnaissance survey is an integral part of the PRA process and complements the desk study. The general objectives of a site reconnaissance are listed in BS 10175:2011+A1:2013. Additional objectives in relation to asbestos in soils and made ground are likely to be site-specific but may include:

�� identify any areas where potential ACMs are visible (particularly when not indicated in the desk study)

�� confirm the presence of visible potential ACMs associated with waste disposal areas, demolished buildings or areas of fill or rubble identified in the desk study

�� evidence of potential asbestos or ACMs in extant buildings and structures

�� evidence of undocumented demolition, waste disposal or imported soils/aggregates.

The critical importance of complying with CAR, and other health and safety considerations, when working with ACSs (including the need for a suitable CAR risk assessment and appropriate training) is discussed in Chapter 8.

Experience in the UK and elsewhere (eg Western Australia, 2009a) indicates that while the desk study should provide indicative evidence for the presence of ACSs, the visual inspection during the site reconnaissance is often the most informative element of the PRA, particularly in relation to



surface contamination. Note that such inspections can only identify visible fragments of potential ACM. Free fibres cannot be seen and so the absence of visible ACM does not mean that asbestos fibres are not present.

The intensity of the walkover needs to be determined on a site-by-site basis but should include the exposed areas of the site, potentially asbestos-containing buildings and structures (or their footprints if they have been demolished) and any debris, rubble or arisings. A systematic grid-based inspection of the site, or individual zones of the site, may be required to effectively identify areas where visible asbestos is present in surface soils (ICRCL, 1990, and Western Australia, 2009a). Waste disposal areas etc may be overgrown and care should be taken that surface asbestos obscured by vegetation is not overlooked, which may require the prior clearance of heavily vegetated sites. CAR 2012 should be complied with during any such clearance and such work may be licensable. Recognising asbestos on a brownfield site is difficult. Those undertaking the site reconnaissance should be, or be accompanied by someone who is, competent in identifying ACMs on brownfield sites (see Chapter 9).

Detailed records of any potential asbestos/ACMs observed during the walkover should be documented and an additional photographic record is recommended. Records should include:

�� type(s) of potential ACMs encountered (eg loose insulation, asbestos cement) plus an indication of the amount encountered (ie five fragments per square metre) (see Figure 10.1)

�� area of the site affected based on visual evidence (where significant free fibre may have been released the surrounding area should also be included)

�� any indication of likely depth

�� condition (ie weathering and friability) based on the most degraded samples found in that area.

Soil sampling is not normally conducted as part of a site reconnaissance (BS 10175:2011+A1:2013), but consideration should be given to the potential advantages of limited sampling with respect to ACSs. For example, samples may be sent for laboratory analysis to confirm the identity of suspected ACM fragments found at surface or to determine if non-visible asbestos fibres are present in surface soils – and this has been recommended elsewhere (eg Western Australia, 2009a). Alternatively, a more-detailed forensic examination of surface soil samples may be conducted on-site to identify the presence of suspected asbestos fragments (these could be submitted for subsequent laboratory confirmation). In the Netherlands, an on-site visual inspection of sampled soils is required as part of an ‘exploratory survey’ under NEN 5707:2003. However, it should be stressed that visual identification of asbestos on site cannot replace the need for soil samples to be analysed in a laboratory – fine fibres are unlikely to be visible to the naked eye. Recognition of soil smeared ACM or even raw asbestos can be difficult!


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note

All these materials were encountered at the same site and illustrate the difficulty of identifying ACMs visually and the need for trained personnel.

Figure 10.1 Examples of ACMs encountered at the surface during a site walkover (courtesy Hydrock)

a Length of yarn (chrysotile) b Textile (chrysotile)

c Fragment of asbestos insulation board (amosite) d Loose insulation (amosite and crocidolite)

e Textiles (crocidolite) f Textiles (crocidolite)

g Fragments of asbestos cement (chrysotile) h Gaskets (chrysotile)



Figure 10.2 Potential sources of asbestos (courtesy VSD Avenue, a consortium comprising VolkerStevin Ltd, Sita Remediation NV and DEME Environmental Contractors BV)

a Asbestos-cement pipework b On-site ‘tip’ containing suspected ACMs at a former industrial site

Summary

�� all of the DoE industry profiles identify asbestos as a potential contaminant of concern

�� some industries have a high likelihood of asbestos, such as railway workshops, depots and siding areas, including ballast, ship builders, repairers and breakers, old waste disposal sites and made ground, scrap yards, power stations, including boiler houses, pre-1980s fire or storm damage, sites with buildings, or former buildings, containing ACM or asbestos insulation materials (eg asbestos roofing, sheds, garages, water tanks and boilers), and disused services with ACM piping

�� the potential for ACSs to be present should be considered during the PRA at all sites unless adequate justification for not doing so can be documented (eg records of the pre-demolition survey available and records of any later asbestos removal and disposal).

�� although less likely, asbestos may be present at greenfield sites, as asbestos-containing wastes could have been imported, tipped or deposited

�� where structures have been demolished the potential for asbestos to be present and the likely type and amounts of such materials should be adequately considered based on factors such as the age of the demolished structures and when the demolition occurred

�� where asbestos may be present additional sources should be sought and consulted as part of the desk study in order to adequately characterise the potential for asbestos to be present in soils and made ground

�� any site reconnaissance where ACSs may be present must be conducted in compliance with CAR

�� such site reconnaissance surveys should be undertaken by appropriately experienced and trained personnel capable of identifying potential ACMs, even when smeared with soil etc

�� site reconnaissance surveys may include limited sampling of soils or suspected ACMs

�� significant amounts of asbestos fibres or ACM may be present but not visible. A site reconnaissance cannot rule out the presence of asbestos, but can only confirm that it is present

�� a good desk study suggesting that asbestos is unlikely and a site reconnaissance by a competent person confirming the desk study are enough to confirm “asbestos is not a problem here and further investigation is unnecessary”. However, site management should remain vigilant during investigations and remediation and act quickly should asbestos be encountered.


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11 Soil sampling and analysis of asbestos in soil

11.1 IntROduCtIOnGeneral guidance on designing and implementing a field investigation is given in BS 10175:2011+A1:2013, in the Secondary Model Procedures report (Environment Agency, 2000) and for hotspot delineation in CLR 4 (DoE, 1994).

Once the desk study and preliminary site visit and walkover have informed a conceptual site model (CSM), the important uncertainties identified should drive the site investigation objectives. Due to the highly heterogeneous nature of ACSs, any site investigation should be designed based on a robust CSM. Data from a limited number of random soil samples with no supporting PRA and likely sources etc should never be used to demonstrate the absence of asbestos at any site.

The objectives of the field investigation will be site-specific, but may include:

�� confirming whether asbestos is present on a site

�� quantifying the amount of asbestos and ACMs present

�� waste classification of soils

�� establishing the distribution of asbestos (including locating any caches)

�� informing the human health risk assessment.

To achieve these, appropriate site-specific sampling and analytical strategies are required to ensure appropriate sampling and analytical methods are adopted that yield information that is fit for purpose and of a suitable quantity and quality.

The critical importance of complying with CAR 2012, and other health and safety considerations, when working with ACSs (including the need for a suitable CAR risk assessment and appropriate training) is discussed in Chapter 8.

11 .1 .1 What type of data is required?To date, most field investigations involving ACSs have solely focused on the collection and analysis of soil samples as is common for all other soil contaminants, but in the case of asbestos in soils other techniques may also be needed to support an appropriate soil risk assessment. Guidance from Western Australia (2009a) recommends that such a ‘weight of evidence’ approach is adopted in the case of ACSs, rather than any single method of sampling or analysis, due to the inherent uncertainties associated with ACSs.

Determining the presence and extent of asbestos in the ground is an essential starting point for all investigations. However, any assessment of the potential risks posed by ACSs should also consider the likely circumstances that can lead to the inhalation of respirable asbestos fibres. With no specific UK guidance on the investigation and assessment of such sites, a range of different types of data have so far been used to assess the risks from ACSs in the UK, including:

AimThis chapter describes and reviews sampling and analytical requirements, strategies and methods used to provide the information needed for soil risk assessments associated with ACSs. The ‘toolbox’ of methods potentially able to inform this risk assessment is also presented. Quality assurance, errors, accreditation and the skills sets required of individuals undertaking these measurements are also reviewed.



Asbestos in the soil:

�� qualitative tests for the presence of ACM (and free fibres) in soil samples (note that historically some qualitative tests only reported the presence of fragments of ACM and were not sufficiently detailed to determine if free fibres were or were not present)

�� quantitative measurement of the concentration of ACMs (excluding free fibres) in soil samples

�� quantitative measurement of the concentration of ACMs and free fibres in soil samples.

Potential release of asbestos:

�� measurement of the potential fibre release using laboratory tests of soil samples (known as ‘dustiness’ testing).

Indoor spread:

�� measurement of asbestos fibres in indoor dust deposits.

Airborne asbestos:

�� measurement of airborne asbestos in indoor air (including static and ‘activity-based sampling’ methods)

�� measurement of airborne asbestos in outdoor air (including static and ‘activity-based sampling’ methods).

Some advantages and disadvantages of available methods are summarised in Table 11.1. Depending on the circumstances, one or a combination of methods may be appropriate, but site-specific considerations and the data requirements of the intended soil risk assessment should determine the methods adopted.

The data requirements should have a significant influence on the investigation design, which should be clearly reported in the sampling strategy and subsequent reporting. So, for ACSs (as for other contaminants) access, sampling and analysis methods are separate components of the overall investigation design that cannot be considered in isolation. The sampling methodology should be compatible with the analysis and with the means of accessing the material to be sampled.


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Advantages disadvantages

Soil sampling and quantitative analysisSee Sections 11.2 and 11.3

�� ascertains whether or not asbestos, particularly fibres and fragments too small to be visible, is present in soil

�� the analytical methods are based on standard techniques well proven for asbestos in bulk materials

�� testing is commercially available in the UK

�� guidance is available on developing soil sampling strategies for specific sites and appropriate sampling procedures

�� unaffected by weather during sampling (unlike air monitoring methods)

�� moderate cost allows large numbers of samples to be collected, if needed, to adequately characterise the site.

�� samples may not be representative of the site as a whole due to heterogeneity

�� accuracy may differ between soil types and for different ACMs etc

�� airborne fibre concentrations (needed for use in quantitative health risk assessment) can only be estimated indirectly and are subject to significant uncertainty

�� estimating actual airborne fibre concentrations requires assumptions regarding respirable dust concentrations

�� assumes that soil samples collected are representative of the entire site/zone (note that contamination is generally highly heterogeneous and localised caches may exist).

Outdoor environmental air monitoringSee Chapter 12

Note: this differs from the occupational air monitoring required under CAR

�� provides direct measurement of outdoor exposure to airborne asbestos fibres, which can be used to calculate the risk (under current site conditions)

�� measurements are representative of large areas of the site (including heterogeneity)

�� the analytical methods are based on standard well-proven occupational hygiene methods

�� testing available through commercial companies and laboratories in the UK

�� guidance is available on appropriate sampling strategies for specific sites and appropriate sampling procedures.

�� cannot be measured during unfavourable weather conditions (ie wet ground, cold, high humidity, rain, snow)

�� requires representative site activities to occur during sampling period

�� temporal variations�� potential limits on the duration of sampling or access�� may require upwind and downwind sampling to

attribute the source�� only representative of surface conditions and

activities on site during sampling�� does not represent potential future exposure

following degradation and weathering of ACMs in soil�� many companies/laboratories are often unable or

unwilling to modify standard occupational methods (ie low detection limits). Requires equipment capable of longer term/higher volume sampling to achieve required LoQ

�� SEM/TEM will be required for accurate fibre discrimination and low detection limits, resulting in increased costs.

Activity-based samplingSee Section 12.2.3

�� provides direct measurement of outdoor exposure to airborne asbestos fibres, which can be used to calculate the risk (under current site conditions)

�� uses methods and equipment commonly used for occupational monitoring

�� method recommended by US EPA.

�� cannot be measured during unfavourable weather conditions (ie wet ground, cold, high humidity, rain, snow) unless by enclosing area and drying the ground, which is not always practicable

�� data is only representative of a small area of the site�� potentially incompatible with CAR due to ‘intentional

exposure to asbestos’�� does not represent potential future exposure

following degradation and weathering of ACMs in soil�� relatively labour-intensive, so costly.

Table 11.1 Comparing the potential advantages and disadvantages of different lines of evidence for use in estimating potential human exposure



Advantages disadvantages

Indoor surface dust samplingSee Section 11.3.4

�� can indicate the potential presence of asbestos fibres in indoor air

�� may indicate ‘track back’ of asbestos from exterior soils

�� samples can be collected quickly and simply

�� indicates conditions over a considerable period before sampling.

�� interpretation is difficult and cannot be used to determine indoor air concentrations or exposures

�� no standard sampling or analysis method in the UK and sampling efficiencies can vary between surfaces

�� may require electron microscopy due to the fine asbestos fibres and non-asbestos fibres encountered

�� results reflect the activities of the current occupancy of the building and, in domestic housing, do not take account of different lifestyles

�� cannot be used to assess contribution from outdoor soil in houses that have ACMs or in houses from which ACMs have recently been removed owing to difficulty in attributing the source

�� may be affected by other sources, eg occupants may bring contamination from occupational exposure to asbestos, which could lead to para-occupational exposure

�� access required to private properties�� does not account for future weathering of ACMs.

Indoor air monitoringSee Chapter 12

�� provides direct measurement of indoor exposure to airborne asbestos fibres, which can be used to calculate risk

�� the analytical methods are based on standard, well proven occupational hygiene methods

�� testing available through commercial companies and laboratories in the UK

�� common household activities that disturb dust can be replicated during sampling to increase representativeness.

�� results reflect the activities of the current occupancy of the building and, in domestic housing, do not take account of different lifestyles

�� many companies/laboratories are often unable or unwilling to modify standard occupational methods (ie unable to monitor to low detection limits)

�� relatively high non-asbestos fibre concentrations in residential properties make fibre counting by PCOM inappropriate

�� SEM/TEM is usually required to discriminate between different fibre types increasing costs

�� the contribution from outdoor soil to indoor airborne asbestos may be difficult to distinguish from other sources if there are ACMs in the building or ACMs have recently been removed from within the building. The presence and possible significance of other sources needs to be assessed

�� access required to private properties�� does not account for future weathering of ACMs.

Measurement of fibre release potentialSee Section 11.3.3

�� provides a direct measurement of the normalised airborne fibre concentration that can be generated from soil samples

�� unaffected by weather during sampling (unlike air monitoring methods)

�� possibly more useful for research into soil-to-air relationships, but may be appropriate for routine testing when justified by special site requirements

�� not widely available in the UK, but HSL do offer such testing of soils (see Box 11.4)

�� tests are relatively expensive compared with soil analysis. Testing a small number of samples may not be representative of the entire site/zone, due to heterogeneity etc

�� fibre concentrations in tests do not directly reflect actual asbestos exposures and need to be normalised against airborne soil-dust concentrations

�� additional allowance may be needed for the aggressive disturbance involved during the test

�� additional allowance may be needed for the low moisture content of the materials necessary during the test, ie to estimate airborne concentrations that will arise over time given the variable moisture conditions on site

�� estimating exposures also requires assumptions regarding respirable dust concentrations

�� does not represent potential future exposure following degradation and weathering of ACMs in soil.

Table 11.1 Comparing the potential advantages and disadvantages of different lines of evidence for use in estimating potential human exposure (contd)


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11.2 SOIl SAmplInG StRAteGyThe principles of decision making described in BS 10175:2011+A1:2013 apply to asbestos in much the same way as to other contaminants. Soil sampling is needed to establish if asbestos is dispersed in soils (including the types and concentrations) but the extent of soil sampling will depend on the aims of the investigation and context (eg site history, findings of preliminary investigations, CSM, nature of the site and its current and future use) (Table 11.2). Higher sampling densities than normally employed for most other contaminants should be considered due to heterogeneous asbestos content.

Where localised asbestos caches, such as buried asbestos cement or board, waste disposal pits and dumps, are suspected, the sampling strategy may consider:

�� likely locations for such caches (from desk study information)

�� the potential risks to workers involved in disturbing such materials

�� the current (and future) land uses

�� the intended management option for such areas (eg are such materials likely to be left in situ?)

�� what information is required:

i Is it sufficient to simply confirm the presence of buried materials?

ii Does the lateral extent need to be determined?

iii Does the vertical depth need to be determined?

However, it is generally impossible to rule out the presence of such caches, and effective procedures are needed to manage them if they are encountered during redevelopment.

In some instances, there may be benefits in conducting the investigation in phases, with supplementary phases required to assess the nature and size of localised caches or resolve spatial uncertainty.

Table 11.2 Factors to be considered in designing an investigation of asbestos-containing soils

Component of soil sampling strategy Examplesoffactorsinfluencingthesamplingstrategy

Data requirements (quantity, type and quality) for the planned soil risk assessment

The likely target requirements for acceptable levels of asbestos, which will depend on the proposed or current land use. (In all cases the methods need to be capable of measuring free fibres and ACMs in soil).Variation between samples can be large if the asbestos is present in relatively large fragments of ACM. Asbestos is stable and not mobile in soil, so adjacent samples can contain very different quantities of asbestos. This can preclude standard statistical approaches to data analysis and decision making (in particular guidance from Harris et al (2008) is likely to be of extremely limited use), particularly in small areas. Large inter-sample differences can be real and are not a sign of false measurements. Decisions may need to be made on the basis of a ‘balance of probabilities’.

Site zoningZones may be appropriate, for example, on larger sites where there are suspected localised caches or if sites have been re-profiled.Alternatively a receptor-focused averaging area approach may be adopted.

Distribution of samples

Sampling locations will be determined by site size, site history and findings of the PRA as well as the aims of the investigation.The samples should, at least, delineate the horizontal extent of asbestos.Sampling would normally be targeted at areas of concern identified in the PRA (where sufficient information is available), but it may also be necessary to consider other areas of the site.Grid-based sampling may be required to counter the usual heterogeneity in the distribution of asbestos in soils (even when sampling is targeted).Greater sampling densities and volumes should be adopted than normally employed for other contaminants.The locations from which samples were taken need to be accurately recorded to inform subsequent data evaluation and remediation option appraisal.



Depth of sampling

It is vital that samples are collected from appropriate depths in order to support a robust assessment of potential risks.Sampling depth will be determined by the current or future use of the site and the findings of the PRA.The depth of sampling should also take account of ‘cut-and-cover’ or ‘cut and fill’ operations that will alter site levels. In all redevelopment situations, sample depth should relate to final site levels as only these will be representative of the potential post-development exposures.The depths from which samples were taken need to be accurately recorded to inform subsequent data evaluation and remediation option appraisal.

Sample size and sampling protocol

Sample size influences how representative the sample is of the soil being investigated. The sample size should be determined by the best compromise between obtaining a representative sample and what can be reasonably handled by laboratories. Smaller samples are less representative but require less on-site handling so reduces worker exposure. A balance needs to be struck between operator safety, sample size and sample numbers.BS10175 generally advises against composite sampling for any contaminants.

Where assessment of imminent risks is the primary aim, sampling should normally be concentrated on near surface soils (ie <0.2 m below ground level (mbgl)) from which asbestos can become airborne. Greater depths should be sampled where there is a reasonable likelihood that burrowing animals or physical disturbance may bring asbestos to the surface. Double digging by keen gardeners may expose soils from ~0.6 mbgl and the installation of a garden pond from >0.9mbgl. Generally, sampling from even greater depths will only be needed to estimate remediation volumes or to characterise potential occupational risks from earthworks involving these deeper materials.

The chemical and physical stability of asbestos and its relative immobility in soil mean that hydrology and hydrogeology do not require special consideration except in the situation where gross washout from a site is expected as this may result in the spread of ACSs and sediment.

In summary, there is no single sampling strategy applicable to ACSs and strategies need to be developed on a site-by-site basis. Any strategy also needs to collect adequate data on other potential contaminants. This can make the design of such investigations more challenging and require innovative solutions.

11 .2 .1 Access methodsMethods of accessing the relevant soils for sampling or inspection need to suit the size of the site and the available access. For the investigation of ACSs, the potential for fibre release during access and transport and post-sampling (ie asbestos exposed at the site surface following trial pitting etc) should also be considered. BS 10175:2011+A1:2013 (Section 8) outlines various access methods, their advantages and disadvantages and the space required for undertaking the investigation but does not specifically deal with issues regarding asbestos. Some specific asbestos issues for common sampling procedures are outlined in Table 11.3.

Table 11.2 Factors to be considered in designing an investigation of asbestos-containing soils (contd)


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Table 11.3 Some common access methods and considerations for use with asbestos-containing soils

Sampling method Asbestos considerations

Rotary boreholes�� potential poor recovery of superficial materials�� high potential for fibre release (do not use air flush)�� able to access much deeper depths.

Cable percussive

�� low potential for fibre release in saturated soils�� lengthy set-up time if many samples required�� equipment size a disadvantage in confined areas.�� able to reach deeper depths�� suction of shell withdrawal could generate airborne fibres in dry made ground.

Hand auger

�� suitable sample size for sending directly to a laboratory, so no on-site treatment�� easy access for gardens or similar�� little mess�� minimal disturbance. Lower potential for fibre release.

Hand pits�� on-site sample treatment before despatch to laboratory�� small potential for fibre release but readily controlled.

Dynamic sampling�� small sample size, no treatment but may be less representative�� percussive driven sampling will increase potential for fibre release.

Trench/trial pit

�� some potential for fibre release, particularly in dry conditions. May be controllable with effective damping down and PPE etc

�� exposure of the public should be considered (eg excavations near boundaries)�� allows large sample sizes to be collected (but this may require on-site preparation)�� potential for spread of asbestos, particularly at surface�� lots of damage�� provides greater visualisation of soil horizons, increasing chances of identifying

heterogeneous ACM.

Power driven augers�� sample size suitable for sending directly to a laboratory�� higher potential for fibre release than hand auger.

Sonic drilling�� good recovery of superficial materials, gravel and cobble sized fragments�� able to reach greater depths�� increased potential for fibre release.

Historical UK guidance (ICRCL, 1990) only suggested that “Trial pits have the advantage of allowing the ground conditions at depth to be observed directly, but if the site is heavily contaminated it may be better to use boreholes in order to minimise disturbance”. Steeds et al (2000) have also stated that rotary and down the hole hammer drilling are unlikely to be suitable but that “Window sampling is, under controlled conditions, suitable for investigations into ground known to contain difficult to manage materials such as asbestos and highly odorous wastes as only very small quantities are brought to the surface, very little ground is opened up and excess spoil requiring specialist disposal can be avoided.” Similar comments are made with respect to hand-held drilling tools. Steeds et al (2000) also advised that “if unmanageable materials (eg unexpected friable asbestos) are encountered:

the trial pit should be aborted and backfilled and the method of investigation and health and safety arrangements re-appraised. If large amounts of contaminated materials or dusty/odorous conditions etc are present, trial pits may be an inappropriate method for investigation drilling should be halted (leaving augers in the ground), the hole covered with a sheet, board or otherwise and method of investigation and health and safety arrangements re-appraised.”

It should also be noted that under CAR, the known or likely presence of asbestos needs to be explained and communicated to any drilling or earthworks subcontractor. Such sites would be classified as ‘red’ under the British Drilling Association’s site designation system (see Table 11.4) and so additional costs are likely to be incurred.



Table 11.4 BDA site designation (after BDA, 2008)

designation broad description Comments with respect to asbestos in soil

RED

Substances that could subject persons to risk of death, injury or impairment of health. Examples would be any substances that are corrosive, acidic, carcinogenic, cause skin irritation or respiratory problems, affect the nervous system, affect the organs etc.See [below] in respect of ground gas.

Sites known to have or with a history making it highly likely that they have ACSs

YELLOW

Substances that are not sufficiently harmful to potentially cause death, injury or impairment of health but nevertheless require protection to be worn to ensure that any health issues do not arise. Examples would be waste food, vegetable matter, household and garden waste, leather, tyres, rubber, latex, electrical goods and fittings, non-toxic metals, bitumen, fuel ash and solidified wastes.Where there is potential for significant volumes of ground gas at concentrations that arc toxic, flammable or could cause explosion, then a RED category should be used.

Sites where ACSs may be present.In such cases the possibility of asbestos being encountered should be considered in the health and safety risk assessment and suitable procedures be put in place should ACSs be encountered.

GREEN

Substances that have little potential to cause significant permanent harm to humans. Examples would be uncontaminated natural materials including topsoil, hard core, bricks, stone, concrete, excavated road materials, glass, ceramics, abrasives, wood, paper, fabrics, cardboard, plastics, metal components, wool, cork, ash, clinker etc provided that these do not contain other substances that could be significantly harmful to humans.Note that topsoil and sub-soil may be contaminated and that there is a possibility of bonded asbestos being present in otherwise inert areas. In these cases a YELLOW category applies.

Sites where asbestos is not expected.

notes

1 A greenfield site would normally be included in the GREEN category unless there is evidence to indicate a YELLOW category.2 Indiscriminate dumping (or in the case of older sites, uncontrolled/unlicensed landfilling) may have taken place on a site and this should

be taken into consideration when determining the appropriate category.3 Landfill sites or other sites where significant deposits of bound or unbound asbestos occur should have a RED designation. However,

other sites may have only very small quantities of asbestos, often present as asbestos cement, which whilst presenting a hazard may not on its own justify the highest level of protection. In these cases it may be sufficient to simply add water to the borehole or other form of intrusive activities to prevent asbestos fibres becoming airborne and hence available for inhalation and to wear disposable masks suitable for low levels of asbestos.

4 The presence of radioactive materials on a site is not included in the above guidance and appropriate references on this should be consulted including regulations.

5 A desk study and a risk assessment must be carried out before the site is categorised (see Chapter 5). As part of the desk study, a site walk over must be undertaken. This should look at both the site and the land usage surrounding the site.

6 If the site itself has an indicative classification, eg YELLOW, but it is believed that surrounding site usage may have caused contamination to the site that would be classified as RED, the site classification must be upgraded to RED.

7 If after carrying out the desk study and reviewing the previous usage there is doubt as to which category should be assigned, the higher of the two categories under consideration should be taken.

8 Once the site category has been determined this should lead to requirements for safe working practices and the use of appropriate PPE and RPE.9 If, after a category has been assigned to a site, further information becomes available that warrants a change of category then the category

should be changed accordingly and all site personnel immediately informed. This includes information from the investigation itself.10 If changing a site category results in the required PPE and/or safety equipment not being available then the work must be suspended

until they are available.

11 .2 .2 Soil sampling protocolWhere samples are required for laboratory testing, a sampling protocol should be prepared on a site-specific basis. Guidance on sampling is given in BS 10175:2011+A1:2013, which notes that composite sampling should not normally be used but introduced the concept of ‘cluster sampling’ as an appropriate strategy for surface samples and in certain other circumstances.

No guidance on an appropriate sampling protocol for asbestos in soil has been published in the UK, but a number of proposed protocols have been published in the US (eg Berman and Kolk, 2000) and the Netherlands (NEN 5707:2003).

In order to address the heterogeneity inherent in ACSs, many of these protocols involve the collection of very large samples and/or composite sampling. However, to produce a sample of suitable size for


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off-site analysis (normally between 0.5 and 1.5 kg) such protocols usually involve significant on-site mixing, treatment and sub-sampling, which has the disadvantage of increasing potential exposure of site workers. Also, compositing introduces significant problems if the physical extent of contamination across a site needs to be determined, hides the true variability of asbestos across the site, and can prevent the application of a (geo)statistical evaluation to the distribution of asbestos or any other contaminant in such samples. Compositing samples may also require mixing and sub-sampling on site.

There are technical and quality advantages and disadvantages to on-site processing and sub-sampling. Done correctly, it means that samples are representative of larger volumes of soil and results are more representative of the material being sampled. However, there are pitfalls. Asbestos is often found in large fragments that need to be treated correctly to avoid error. Ignoring or excluding such fragments from sampling leads to erroneously low results. Retaining too many large fragments leads to excessively high results. One solution is to weigh the original sample on site and remove large fragments of suspect ACMs before coning and quartering (or other sub-sampling processes). However, as results are reported on a dry weight basis, this also requires the moisture content of the soil and ACM fragments to be estimated. The large fragment(s) can be returned to the laboratory where it can be analysed and its contribution to the asbestos content of the initial sample can be calculated.

Where contamination is dispersed, then the sub-sampling is more reliable and can be conducted with soil samples in dried controlled conditions. Only a trained and demonstrably competent operator should undertake on-site sub-sampling. Any lesser quality control in on-site sample preparation could add significant error into the results. The practicalities of on-site work – especially in poor weather and light conditions – make stringent quality control inherently more difficult.

Occasionally the nature of ACMs make sub-sampling impracticable. This was the case as described by Robertson et al (2011) where large fragments of loose amosite insulation were found in domestic gardens. This precluded sub-sampling as it could have released significant amounts of loose fibre. Larger samples were sent to the laboratory where they could be handled in controlled conditions. The main drawbacks of this approach were difficulties in sample transport and storage and the generation of large quantities of waste.

With regard to assessing the potential for ground gas generation, Card and Wilson (2011) recently proposed the use of forensic description to provide more detail on made ground composition than is usually captured in investigation logs. A similar on-site approach has been applied in the UK to the characterisation of ACSs and made ground (Box 11.1), but avoids some of the drawbacks associated with other sub-sampling methods. The Dutch NEN5707:2003 standard is also understood to include a similar visual inspection of soil samples as part of an ‘exploratory survey’. However, such descriptions cannot be used to demonstrate that asbestos is not present as the identification of asbestos fibres requires laboratory analysis of soil samples.

A sampling protocol that is appropriate to the site, the objectives of the investigation and the requirements of the soil risk assessment, should be prepared for each investigation. It should clearly outline the sampling method to be employed and the justification for its selection.

Box 11.1 Encountering ACM during a site investigation (courtesy James Clay, Campbell Reith Hill LLP)

Site worksA site-wide investigation identified suspected ACM during trial pitting. Supplemental works, under the supervision of a trained asbestos supervisor with full health and safety provisions and monitoring, were then completed using trial pits. The intent behind this work was to prove the viability of a site based remediation for substantially asbestos-contaminated soils and a different, and more simplified, quantification approach can be taken when considering purely quantum (rather than risk).

The works were specified and tendered as part of an exercise to both delineate and quantify asbestos in soils across an area of the site and also then to compare the quantification results obtained from different forms of available analytical techniques.

The works comprised the completion of 20 no. trial pits and linear trenches, which were visually logged in duplicate by a trained asbestos surveyor and an experienced environmental scientist. The asbestos specialist produced detailed schedules of the potential asbestos type, form, condition, depth and frequency while the environmental scientist closely recorded the strata (recognising that both moisture and soil structure have a substantial effect on fibre liberation). This



Box 11.1 Encountering ACM during a site investigation (courtesy James Clay, Campbell Reith Hill LLP) (contd)

HSE (2005) states that all samples “must be individually sealed in their own uniquely labelled container, which is then sealed in its own second container or polythene bag”. Soil samples that may contain asbestos fibres or fragments of ACM should be treated in the same manner and labelled as ‘potential asbestos’ before being dispatched to an off-site laboratory. The Royal Mail classes ‘asbestos’ as a ‘prohibited item’ and so ACS should not be sent by post, but may be sent via a courier who is willing to carry such materials or delivered to the laboratory by the sampler.

was to facilitate a corroborated visual description of the ground and types of potential ACM within it.

A detailed sampling and analysis protocol was then devised. Duplicate 2.5 kg samples (A and B) were taken at one metre intervals throughout each trial pit. B samples were retained for later reference and A samples combined in the manner described in a draft HSL method (later withdrawn) and submitted for both experimental analysis by the HSL (water suspension tests and dustiness tests) and ‘routine’ commercial laboratory analysis (using polarised light microscopy according to HSE (2005) protocols). Geotechnical testing was also completed to determine soil particle size, moisture content, plasticity and other parameters that would affect the viability of soils treatment.

The inspection works identified a pattern of occurrence of suspected ACM in particular strata and locations and also their primary forms (cement sheet, fibrous insulation, paper, gasket and cloth), and allowed visualisation of asbestos occurrence.

AsbestosfibrereleaseworkThe laboratory analysis assessed in parallel for the samples:

�� the calculation of overall asbestos content in weight�� asbestos content according to HSE (2005) method (bulk and soil fibre bundles ID)�� the number of fibres released via water suspension tests�� the number of fibres released via experimental dustiness release testing.

A tabulation of the various tests was then produced and a statistical examination made of the correlation between tests for samples.

There was a very poor association between the amount of bulk asbestos products noted within the soil profile and the level of dispersed asbestos by weight (which in-turn reflect a greater risk).

hazard assessmentUltimately a hazard weighting was produced. This comprised producing a hazard weighting, which considered the proportion of free asbestos in soils, and applied a mesothelioma risk adjusted weighing factor, which considered the different types of asbestos within a sample and their associated potential to cause harm. This was expressed as a hazard weighting and later compared to dustiness testing results.

health and safety controlsThe site investigation and a site-based remedial trial were completed in tandem. The works were specified and agreed with the HSE who also attended the site briefing and awareness training for all personnel involved in the work. Full CDM documentation (including health and safety plan and F10 form) were prepared by the successful contractor for the investigation and remedial trials and the works were continually overseen through by an independent asbestos specialist who completed air and health and safety monitoring services. Health and safety protocols considered HSG 66 (HSE 1991) and a decontamination unit to [HSE standards on hygiene facilities for work with asbestos insulation and coatings].

Figure 11.1Suspected ACM fragment collected from soil. Later laboratory analysis confirmed the presence of asbestos within this material (courtesy VSD Avenue, a consortium comprising VolkerStevin Ltd, Sita Remediation NV and DEME Environmental Contractors BV)


CIRIA, C73394

11.3 AnAlySIS Of ASbeStOS In SOIlA range of potential analytical methods and tests are available in UK laboratories that can be applied to samples of ACS. The method(s) required should be defined on a site-specific basis based on the CSM and overall aim of the investigation. The accreditation requirements for soil analysis are discussed in Section 11.3.5.

Where asbestos concentrations in soil are to be used to assess potential risks to human health, any analysis should be conducted using a validated method with both detection limits and quantification limits of 0.001 per cent or less (ICRCL, 1990).

Such quantitative analysis of asbestos in soils can be undertaken successfully using techniques based on optical microscopy but under some circumstances more sensitive or selective test may be needed (eg using electron microscopy) or a different type of test may be more appropriate (eg measurement of fibre release potential).

To adequately characterise the risks, any analysis of soils should also include identification of the type of asbestos present (ie chrysotile, amosite and crocidolite) as well as the quantity. For the large fibres commonly found in ACMs and soils, fibre identification by PLM is definitive.

11 .3 .1 Soil analysis using optical microscopyThere is currently no standard methodology for the quantification of asbestos in soils, and different laboratories apply different in-house methods. The range of methods is evolving to meet client requirements. However, a summary of the general techniques commonly employed at present is as follows.

The identification of asbestos in bulk materials, including soil, is currently dominated by methods based on polarised light microscopy (PLM). In the UK, these are generally based on the methods described by the HSE in HSG248 (HSE, 2005), which involve an analyst visually identifying asbestos fibres using an optical microscope. Although it does not currently make specific reference to the analysis of soil samples, the methods for the analysis of asbestos in bulk materials (HSG248 Appendix 2) can be applied to ACSs. It is a qualitative method to identify if any asbestos is present, and if so, the type(s) of asbestos present. The analysis begins with a visual analysis by picking through the whole of the ~ 1 kg soil sample in a tray for ACMs or larger bundles of fibre. This is followed by progressive sub- sampling to examine 20 g to 30 g under a stereo microscope and then < 1 g at ×100 – ×500 magnification. The type of any asbestos identified is determined by PLM. HSG248 (HSE, 2005) states that “with careful application of this method, a single fibre may be found in a few milligrams of dispersed material. In theory, for a fibre about 100 µm long by about 2 µm diameter, this implies a detection limit in the order of 1 ppm by mass”. This is equivalent to a detection limit of at least 0.001 per cent, but it is debatable if this can be achieved routinely for ACSs. Theoretically, the detection limit can be extremely low, simply by continuing the inspection for longer.

If the mass of asbestos needs to be quantified, procedures described by Davies et al (1996) and further developed by Schneider et al (1998) can be used. These methods include an additional water dispersion step that assists in quantifying fine fibres. These methods can routinely achieve a limit of quantification of 0.001 per cent in soil, including free fibres. A similar water dispersion method is described in the Dutch NEN 5707:2003 standard.

This step-wise process means that quantitative analysis can be phased, such that subsequent steps are only conducted if they are required to meet the analytical objectives. For soil risk assessment purposes, it is the concentrations of ‘releasable fibres’ that are of greatest concern. Where friable or degraded ACMs are visible, this is likely to constitute the majority of the ‘releasable fibres’ and further quantification of free fibres may be deemed unnecessary. However, where visible ACM is not present, or is primarily well-bonded asbestos cement, it may be important to quantify free fibre concentrations. Consultants need to justify their analytical strategy on a site-specific basis.



It should be noted that quantitative analysis is also used for waste classification, but methods designed only to determine if the hazardous waste threshold (see Section 3.6) is exceeded are unlikely to be appropriate for soil risk assessment. So, care should be taken when commissioning quantitative analysis to ensure that it meets the objectives. Accreditation requirements for such testing are discussed in Section 11.3.5.

Box 11.2 The main steps commonly used in the quantification of asbestos in soil (based on HSE, 2005, and Davies et al, 1996)

Inter-laboratory studies (of ‘selected’ participants) in Europe led to results ranging up to two orders of magnitude. The accuracy of such measurements should be considered where such data is being used to estimate potential exposures. The reproducibility in the analysis differs between ‘picking and weighing’ of ACM fragments and ‘fibre counting and sizing’ of individual fibres. IOM experience is that the reproducibility of picking and weighing using individual kg samples is in the order of ±10 per cent. In samples with heavier contamination, most asbestos is normally found by the picking and weighing process. With optical fibre counting and sizing, measurement uncertainty is greater. Sizing to nearest 0.5 µm width and 5µm length by visual comparison gives significant rounding errors and operator differences in addition to the usual uncertainties associated with fibre counting of ±20 per cent. For mixtures with 0.001 to 1 per cent asbestos, the mean determination of asbestos content made by two analysts was between 0.5 and two times the true quantity of asbestos. Results reported by two counters for the same sample differed on average by 40 per cent of the mean value. So, the relative uncertainties are greatest for samples with low asbestos contents, but this represents a small amount of asbestos in the soil.

The manual nature of the visual identification using a microscope means that it is time consuming and taxing for the analysts involved. For this reason, HSE (2005 Table A2.4) states the maximum number of soil samples an analyst can usually analyse in a 24 hour period is 20, and that if more samples than this are to be analysed “at least 20% of the extra samples should be reanalysed, preferably by a second analyst”. Such a relatively low throughput per analyst necessarily makes such testing more expensive than many other tests routinely applied to contaminated soils.

Box 11.3 Certificates of analysis for quantification of asbestos in soil

�� weighing the dried soil sample�� hand-picking and collecting ACM in the soil sample�� weighing each type of collected ACM and, using standard percentages of asbestos in given ACMs, calculating the

mass and percentage of asbestos in ACMs in the soil�� dispersing a weighed portion of soil, suspending it in aqueous solution (ie ‘water dispersion’), filtering aliquots

through a membrane filter and measuring and counting the asbestos fibres using phase contrast optical microscopy (PCOM), similar to that used for air monitoring (see Chapter 12). The volume of free fibres counted is converted to mass of asbestos and the percentage of asbestos as free fibres in the sample calculated

�� the total asbestos content is calculated as the sum of the percentages of asbestos in ACMs and as free fibres. In most, but not all, instances where high asbestos in soil concentrations are found, the majority is present in ACMs.

�� name of the client/client organisation�� description, or reference, of the method used�� client sample number (if supplied to the laboratory)�� date when the sample was collected (if supplied to the

laboratory)�� date received by the laboratory

�� the sample location and depth (if supplied to the laboratory)�� whether asbestos is present and, if so, the type(s) of

asbestos�� the type of ACM (if any)�� the amount of asbestos in the soil (mass percentage)�� the limit of quantification.

Certificates of analysis for quantification of asbestos in soil should include:


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11 .3 .2 Other methods of quantifying asbestosA wide range of other methods have been used to quantify asbestos in soil both in the UK and internationally:

�� some laboratories use methods similar to the quantitative method described in Section 11.3.1 but weigh asbestos rather than measure and count the individual free fibres. This will reduce the errors associated with measuring individual fibres but will introduce others as it requires the identification and removal of asbestos from soil samples

�� PLM methods are used in the CARB (1991) test method. The protocol incorporates crushing and grinding of rock aggregate, and then sieving (200 mesh) to generate a relatively homogeneous material of sufficient particle size to include asbestos fibres. This method is defined as reliable at concentrations >0.5 per cent (US EPA, 2008) and so is not sensitive enough for UK assessments of contaminated land

�� the US EPA (1997) published a screening method for asbestos in soils. This is not fit for the purpose of assessing asbestos in soils

�� SEM and TEM (rather than optical microscopy) have been used to identify and quantify asbestos types in soil samples (US EPA, 2008). These procedures are expensive, involve substantial sample preparation and, at the time of writing, very few laboratories in the UK are set up to undertake routine soil analysis. The benefits of SEM and TEM are that finer fibres can be detected and identified than by PLM. However, this is of limited value for soil samples where the asbestos is most commonly present in either ACMs and/or free fibres that are sufficiently large to be seen by optical microscopy.

�� US EPA (2012) has reported a developmental, rapid-screening infrared method for use in determining the presence of Libby natural amphibole asbestos in soil at low concentrations. Note that at the time of writing, the sensitivity of this procedure or its application to ACMs in brownfield sites was not known.

11.3.3 Measurementof‘fibrereleasepotential’Such tests generally measure both respirable dust concentrations and airborne asbestos concentrations in air generated from a dry soil sample by applying vigorous physical disturbance. They are also referred to as ‘dustiness tests’.

Data on the ability of ACSs to liberate airborne asbestos fibres would be very useful in assessing the risks posed by such soils. Ideally this would involve on-site measurements, using air monitoring or activity based sampling (see Chapter 12), during worst case dry and dusty conditions. However, such conditions rarely occur during on-site measurements, which are also affected by other variables. Conducting measurements under controlled conditions in the laboratory seeks to minimise such variables. Such tests measure the current ‘releasability’ of asbestos fibres. They cannot be used to predict future airborne fibre concentrations following prolonged weathering and degradation of ACMs in soils but the vigorous process will go some way to accelerating such weathering and degradation during the test procedure.

The pioneering work of Addison et al (1989) was essentially based on the use of two experimental test methods. The first used equipment for animal dust inhalation experiments, which generated continuous stable dust concentrations. Samples were collected from an aluminium and Perspex chamber (1.3 m3) supplied with an air flow of 10 to 40 L/min. Soil-derived dust was produced by a modified Timbrell dust dispenser and introduced to an air stream to maintain a respirable dust concentration of ~5 mg/m3. The second design comprised a Perspex box (0.9 m3) in which a transient dust cloud was generated from a 2 g soil sample in a chimney-type device using compressed air (two seconds at 20 psi).

However, a number of alternative methods have now been developed in laboratories in the UK, Netherlands and the USA.

All methods generally apply worst case conditions – they involve vigorous physical disturbance in a confined air volume, which limits dilution, and are normally carried out on dried soils. They generate



much higher levels of airborne dust and asbestos fibres than are likely to be encountered on site. To account for this the results are usually reported as normalised airborne fibre concentrations (ie the ratio of airborne asbestos fibres (f/ml) to respirable dust (mg/m3)). Such normalised data can then be converted to a likely airborne fibre concentration at any given respirable dust concentration. This is discussed further in Chapter 13.

Despite the apparent usefulness of such data in estimating the risks posed by ACSs, such tests are not widely available in the UK. However, a method developed by HSL (see Box 11.4) is available. To date such testing has mainly been used to determine whether areas of low asbestos contamination require remediation or if remediation has successfully reduced asbestos releases to air. Access to such tests could provide risk assessors with a powerful tool in providing robust site-specific assessments of the risks posed by ACSs. However, there are considerable practical and cost difficulties to overcome in ensuring fibre release test results are representative. Dust generation would need to be selected to represent the nature of the activity on the site. The costs would be high to allow for potentially extensive sample preparation, testing, and equipment cleaning to ensure safe operation. It is also likely that electron microscopy would be needed to discriminate between non-asbestos fibres present in the soils. The extent to which these methods would need official validation or accreditation before their use in the UK is contested. Such an undertaking would only be justifiable if it offered a substantial improvement over risk evaluation based on results obtained by data from contemporary analysis of soil samples followed by interpretation based on the findings of Addison et al (1988) and consideration of the ACMs present and ground conditions.

Box 11.4 Outline of various ‘fibre release potential’ tests from around the world

At the very least, research using such methods would allow the current database regarding the release of airborne asbestos (and associated respirable soil dust) from soils, which is essentially limited to that reported by Addison et al (1988), to be expanded to include a wider range of soils and made ground types. This would significantly enhance the robustness of models used to predict such fibre release based on the current limited database.

11 .3 .4 Analysis of indoor surface dustIn addition to the quantification of asbestos in soil, the analysis of asbestos fibres in dust on indoor surfaces may also be of use in indicating the potential for exposure via indoor air.

The HSL has developed a ‘dustiness’ test to assess the potential for soils, and other materials, to release asbestos fibres. This test is based on BS EN 15051:2006. It has been applied to a variety of non-asbestos fibrous materials (Burdett and Bard, 2006) but data on its application to ACSs has not been published. The method involves samples placed in a rotating drum with eight internal vanes through which air is drawn at 38 L/min. Dust and fibres are collected over a one minute period on a series of filters.

The Dutch national framework allows for the use of such a test during Tier 3 assessments. The proposed method involves the collection of a large (>25 kg) composite sample and calculate its moisture content by drying it. The sample is then spread out over an area of 1 m2 in an appropriate extractor cabinet and an adjustable fan is used to apply an air speed over the entire area of 3 to 5 m/s. The airborne fibre concentration is measured at a height of 1.5 m using standard air monitoring methods. Not surprisingly given the test conditions (eg a constant wind direction in the laboratory tests, controlled wind speed, controlled dilution into airborne dust, deliberately dry conditions) such laboratory tests generally produced higher levels of airborne fibres than actual field measurements. It has been speculated that the higher values in the lab tests may also be due to health and safety precautions applied in the field that control airborne fibre emissions (RIVM, 2003).

US EPA developed several test methods including the US EPA Region 10’s glovebox method and the EPA 540-R-97-028 Berman Elutriator method (Berman and Kolk, 1997 and 2000). The latter describes a complex field sampling and preparation procedure to separate and then homogenise the fine fraction (<1 cm) before laboratory analysis. In the laboratory, samples are placed in the tumbler of a dust generator. After conditioning, continuous dust sampling allows the gravimetric determination of cumulative dust loss and TEM analysis is used to identify and quantify airborne asbestos concentrations. Dust and asbestos concentrations in the water-trap scrubber are also determined. Results are presented as asbestos fibres per unit mass of respirable dust and per unit mass of original sample.

An alternative method involving a qualitative asbestos sampler that operates as a fluidised bed is also under development with the aim of being quicker, simpler and cheaper than existing methods (Wright and O’Brien, 2007). This is still believed to be in development and has not yet been validated but it has been employed experimentally at a limited number of sites.


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There are many sampling and analysis techniques in use. Sampling techniques for surface dust are reviewed by Schneider et al (2000). Those that may be suitable for asbestos include micro-vacuuming, wet wipes and various types of adhesive (tapes or gelatine). PLM is routinely used in the UK for asbestos fibre identification in surface dust using the analytical procedures in HSG248 (HSE, 2005). Quantification may be more complex, involving SEM or TEM analysis. Several US standards for quantitative analysis of asbestos in surface dust, published by ASTM (eg D5755-09(2009), D5756-02(2008), D6480-05(2010) D7390-07(2012)) use TEM.

As indoor surface dust levels cannot be used to estimate risks nor definitively link any asbestos fibres detected to ACSs outdoors, such measurements have limited use in soil risk assessment.

11 .3 .5 Accreditation of testingRegulation 21 of CAR 2012 requires testing of “any material to determine whether it contains asbestos” to be accredited to ISO/IEC 17025:2005, or equivalent. This includes the identification of asbestos in soils. It should also be noted that CAR place a duty on anyone procuring such testing to ensure that it is accredited. While CAR only strictly relate to the identification of asbestos, and not to quantification, in practice only accredited laboratories should be used for both.

In the UK, ISO/IEC 17025:2005 accreditation is awarded on a test by test basis by UKAS, so the accreditation of each test needs to be ascertained (UKAS, 2010). There are many UK laboratories that have UKAS accreditation for analysis of materials sampled during building surveys, but a much smaller number of laboratories have the required UKAS accreditation for analysis of ACSs.

UKAS offers three levels of accreditation potentially relevant to ACSs (UKAS, 2010):

�� analysis of pieces of ACM removed from soil samples can be conducted in accordance with the bulk analysis method within HSG248 HSE (2005) to identify the presence and type(s) of asbestos present. However, the reported matrix will relate to the ACM only (eg asbestos cement). Such results will not be representative of the soil as a whole, so such data is of limited value in characterising overall risks

�� tests accredited by UKAS as ‘soil – screening and identification’ will report the presence/absence of asbestos and ACM and determine the types of asbestos involved. The matrix will be stated as ‘soil’ but no quantification of the amount of asbestos can be reported

�� tests accredited by UKAS as ‘soil – screening, identification and quantification’ will report the types and amounts of asbestos present. The matrix will be stated as ‘soil’.

UKAS do not accredit ‘visual screen’ methods that do not involve microscopic examination as these are only capable of identifying ACM fragments. Historically, such methods were widely used within the contaminated land industry. UKAS only accredit laboratories for analysing asbestos in soils using methods that cover all ACMs, fibre bundles and free fibres. It should also be noted that UKAS require all asbestos analysts, as a minimum, to be qualified to BOHS P401 (or RSPH equivalent, if available) and undergo colour blindness tests. In the case of quantification by water dispersion, UKAS also strongly recommend that at least one person per laboratory holds BOHS P403, or RSPH equivalent (if available).

UKAS do not stipulate the analytical methods or procedures used, for example methods may by gravimetric and/or optical and/or electron microscopy. Details of the method should be clearly stated on each laboratory’s test schedule. Accreditation does not guarantee that the detection limit is appropriate for soil risk assessment purposes, for example, some laboratories may hold accreditation for ‘soil – screening, identification and quantification’ only to the hazardous waste threshold (see Section 3.6). So, discussion with the laboratory will be needed to ensure that the testing will be to an appropriate detection limit (UKAS pers comm).

To comply with CAR, care should be taken in ensuring that laboratories have the relevant accreditation for all testing of ACSs. Laboratory accreditations can be reviewed on the UKAS website (see Useful



websites). However, care should be taken to ensure the methods and detection limits are appropriate and that the resulting data will also be fit for its intended purpose.

Accreditation for the analysis of ACSs is not currently available under the Environment Agency’s Monitoring Certification Scheme (MCERTS) (Environment Agency, 2012).

The HSL run a quality assurance scheme, known as the Asbestos In Materials Scheme (AIMS), for laboratories undertaking the analysis of bulk materials using the method described in HSG248 (HSE, 2005). Satisfactory participation in this scheme is mandatory for UKAS accredited laboratories performing asbestos analysis of bulk materials, but it does not include application of the method to soils. A scheme specifically for soil testing, known as the Asbestos in Soils Scheme (AISS), has recently been established by HSL and covers both qualitative and quantitative analysis of soils. Round 1 of the scheme ran between July and September 2013 and the results were not available (at the time of writing). Participation in this scheme is not currently mandatory for UKAS accreditation of asbestos in soil analysis.

Summary

�� soil sampling and analysis should provide data suitable for the intended use (eg waste classification, soil risk assessment)

�� the analysis strategy should be justified on a site-specific basis�� the sampling and analysis have to be carried out in such a way that

personnel are protected and that complies with CAR�� standard intrusive techniques can be used for asbestos in soil despite the

special requirements arising from the immobility of asbestos in soils and the specific health and safety issues

�� there are a range of analytical methods for the identification and quantification of asbestos in soil. Detection and quantification limits should be no higher than 0.001 per cent

�� reports of identification of asbestos in soils and of quantitative analysis of asbestos should report the nature of any ACMs present

�� CAR 2012 requires the use of UKAS accredited methods for asbestos identification in soils

�� methods of asbestos identification based on PLM are appropriate for analysing asbestos in soils

�� quantification of asbestos in soils may be required to inform health and safety risk assessments, quantitative soil risk assessments and for waste classification purposes. Optical microscopy (PLM) and weighing of ACMs and fibre bundles will satisfactorily quantify asbestos in many circumstances but counting of free fibres (by PCOM) may be necessary

�� the detailed method adopted needs to be appropriate for the purpose of the investigation

�� fibre release potential testing of ACSs from sites is not currently a practical option (for site specific testing) but it should be applied in research investigations to investigate the release of fibres from free asbestos fibres and ACMs in a wide range of soils and made ground types to strengthen risk assessment.


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12 Air monitoring and analysis of asbestos in the air

The prediction of risk requires estimates of potential cumulative exposure to be produced. Measurement of the current concentration of asbestos fibres in air (in f/ml) can be used to estimate contemporary exposures (in fibre/ml.hours or fibre/ml.years). However, assumptions may be needed to predict the concentrations in air that may arise in the future, taking account of all foreseeable changes to the land use etc. Airborne fibre concentrations are also very sensitive to weather conditions, so air monitoring data may also need to be extrapolated to allow for annual climatic variations. Obviously, assumptions are also needed to predict the likely concentrations of fibres in air based on soil concentrations as discussed in Section 13.4. As there is uncertainty in all these methods of predicting future air concentrations, a ‘lines of evidence’ approach should be adopted. The inclusion of air monitoring data is likely to be helpful in soil risk assessment at most sites.

The air monitoring strategy should explicitly aim to obtain results relevant to the intended exposure assessment and risk estimation. The air monitoring can be directed towards asbestos in ambient air (on, adjacent to or distant from a site believed to contain asbestos), or asbestos in indoor air, or personal exposures to airborne asbestos during specific activities. A combination of these measurements may be needed. Monitoring may be needed on several occasions and under a range of conditions to accurately assess potential long-term exposures. Specific strategies may need to be used to determine the source of the exposure (eg upwind and downwind sampling, indoor sampling). All air monitoring results need to be reported in conjunction with a detailed description of method used and the conditions during sampling.

As with any other hazardous substance, environmental air monitoring data should only be collected where it is safe and ethical to do so and will be cost effective and proportionate to potential risks at the site. It should neither delay urgent action nor place sampling personnel or the public at risk.

12.1 SAmplInG And AnAlytICAl methOdSThere are internationally accepted technical standards for sampling and analysing asbestos in air. Sampling and analysis are considered together here as most published standard methods cover both.

The principles of all widely-used methods for monitoring asbestos in air are similar. Air is drawn through a filter at a known flow rate for a known period of time. The filter collects all airborne fibres, including asbestos fibres. The filter is treated in a manner appropriate to the analytical method to be used and fibres are identified and counted manually using a microscope. In all these methods only a small portion of the total surface area of the filter is analysed.

The methods are normally based on fibres being counted by PCOM (eg HSE, 2005), SEM (eg ISO 14966:2002) or TEM (eg BS ISO 10312:1995 and BS ISO 13794:1999).

Published background concentrations of asbestos in air have been measured using electron microscopy, normally TEM. Most of the published measurements were produced in the 1980s or 1990s, and there is little more contemporary data. The reported background concentrations in the general environment can be 0.0001f/ml or less (eg WHO, 2000, and Shuker et al, 1997). When monitoring around sites with

AimThis chapter discusses the methods and techniques available to sample indoor and outdoor air and to analyse samples in order to determine concentrations of airborne asbestos fibres. It considers only air monitoring for asbestos for assessing the effect of ACSs on airborne asbestos exposures and consequent risks to health.



ACSs, if civil liabilities are to be avoided it will often be necessary to demonstrate that airborne asbestos concentrations do not exceed such background levels. Such analytical sensitivities can be achievable if much large portions of the filter are examined (involving additional analytical time and expense), larger volumes of air are sampled or if samples taken on consecutive days are pooled to calculate a time-weighted average concentration. Depending on the conditions, it should be possible to achieve analytical sensitivities of less than 0.0001 f/ml using electron microscopy. In any case, to be representative sampling needs to coincide with suitable site activities and weather conditions etc. However, at such levels the impact of false positives associated with non-asbestos fibres can be considerable.

According to HSG248 (HSE, 2005), non-asbestos fibres encountered in air samples include natural organic fibres (eg cotton, hair), synthetic organic fibres (eg aramid, polyester, rayon), man-made mineral fibres (eg mineral wool and glass fibre), and naturally occurring mineral ‘fibres’ (such as wollastonite and diatom fragments). In addition, Burdett (2005) reported high concentrations of gypsum fibres that fit the definition of countable respirable fibres by PCOM. Very high levels of non-asbestos fibres can be present in indoor air but they may also be encountered during outdoor air monitoring at brownfield sites.

Methods involving PCOM are widely used for occupational air monitoring but are generally not sufficiently sensitive or selective for assessing such environmental exposures, and may also miss finer fibres. The PCOM method described in HSG248 (HSE, 2005) involves a minimum sample volume of 480 litres and a minimum count of 200 graticule areas. This has a detection limit of 0.01 fibres/ml, which is not sufficient for monitoring background ambient concentrations. PCOM methods may be suitable for occupational activity-based sampling and may suffice for perimeter monitoring as a first check that fibre concentrations during remediation are not out of control. However, HSE (1998) notes that, if parts of the filter are retained, it is possible for samples initially analysed by PCOM to be re-analysed by either TEM or SEM.

PCOM will give only a total fibre concentration rather than asbestos fibre concentration. So, the presence of non-asbestos fibres can result in false positives where elevated fibre concentrations are reported when asbestos concentrations are actually low. This can lead to severe risk communication issues, the need for additional monitoring, or even unnecessary remedial action, and cause project delays. An example of these problems occurred at Cwmcarn High School, in Caerphilly. The school was closed down on the basis of total fibre counts by PCOM. An HSL investigation using electron microscopy (TEM) discriminated between asbestos and non-asbestos fibres and demonstrated that the concentrations of asbestos fibres in air were much lower than previously reported (SHP, 2013 and links therein).

Although PCOM cannot reliably discriminate fibre types, HSE (1998) describes the use of PCOM fibre counting to enable discrimination of some non-asbestos fibres. The method works for fibres thicker than about 0.8 µm width, but for thinner fibres interference from the filter mount makes it impossible to identify asbestos type using the required optical properties, it cannot achieve the detection limits needed for monitoring ambient air and it is not widely available. So, discrimination between asbestos and non-asbestos fibres is usually facilitated by the use SEM and TEM, which is also described by HSE (1998).

SEM with energy dispersive x-ray analysis (EDXA) allows analysts to effectively discriminate between asbestos and non-asbestos fibres and between amphibole and chrysotile asbestos. SEM can also resolve finer fibres than PCOM, but discrimination of those very fine fibres by EDXA becomes more difficult and is not always achievable. SEM is suitable for most ambient monitoring, indoor air monitoring and activity based monitoring. A special type of filter and specialist pumps may be required. SEM analysis is substantially more expensive (approximately x10) than PCOM and currently only offered by specialist laboratories.

TEM with EDXA and electron diffraction (ED) is the analytical gold standard. The BS ISO 10312:1995 standard allows the analyst to count and identify all asbestos fibres (eg very fine ones) or just the fibres that would be visible by PCOM. TEM gives better resolution, contrast and visibility of fibres than PCOM or SEM and allows definitive fibre identification (including discrimination between amphiboles). The cost depends on the analytical requirements, but for routine analysis TEM is more expensive, and less available in the UK, than SEM.


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Electron microscopy can detect fibres that are not visible by PCOM so the results may not be directly comparable. However any discrepancy is usually limited, as SEM analysis is generally carried out at a magnification that gives similar visibility of fibres to PCOM, and TEM results should report PCOM equivalent (PCMe) concentrations as well as the concentration of other fibre sizes.

Both TEM and SEM are widely used for monitoring background concentrations of asbestos in ambient air.

12 .1 .1 Accreditation of air testingUnder CAR 2012, organisations undertaking air monitoring and fibre counting by PCOM must be accredited to ISO/IEC 17025:2005, or equivalent. To carry out fibre discrimination, the laboratory must be accredited for the discrimination method as well as fibre counting. Individual accreditations are also awarded for the various electron microscopy analyses. To qualify for ISO/IEC 17025:2005, all staff conducting air sampling are required to have, as a minimum, BOHS P404 (or RSPH equivalent, if available), and all analysts conducting fibre counting by PCOM are required to have, as a minimum, BOHS P403 (or RSPH equivalent, if available). In both cases a Certificate of Competence in Asbestos (CoCA) is also acceptable. Satisfactory participation in the Regular Inter-laboratory Counting Scheme (RICE) proficiency scheme is also a precondition for ISO/IEC 17025:2005 accreditation for fibre counting by PCOM.

In the UK, ISO/IEC 17025:2005 accreditation is awarded on a test by test basis by UKAS, so the accreditation of each test needs to be ascertained (UKAS, 2010). There are many UK laboratories and asbestos specialist that are UKAS accredited for monitoring and/or analysis of airborne asbestos fibre concentrations by PCOM. Fewer laboratories are accredited for SEM or TEM.

CAR place a duty on anyone procuring air monitoring to ensure that it is suitably accredited. Clients commissioning monitoring and testing should clarify that laboratories and specialists hold suitable accreditations before commissioning works.

For ambient air monitoring (which is not necessarily covered or required by CAR), electron microscopy techniques and low detection limits are recommended. However, it is recommended that laboratories or asbestos specialists contracted to undertake such work should also be accredited to ISO/IEC 17025:2005 for the relevant methods and detection limits. Accreditation for air sampling according to HSG248 (HSE, 2005), which specifies sampling flow rates and minimum sample volumes, need not prevent the sampling of large volumes to achieve lower detection limits.

12 .1 .2 Analytical errorsCounting errors from a random distribution of fibres on the filter are of the order of ±20 per cent if 100 fibres are counted but at the background levels few fibres will be counted and the variation may be a factor of two or more. Technical errors associated with sampling are in the order of +/-10 per cent. These errors are insignificant compared with the variation in concentrations associated with different activities and in different weather and ground conditions. For example, Addison et al (1988) indicated that the addition of 10 per cent moisture to dry soil reduced its propensity to produce airborne fibres by a factor of between 3 and 15. Also, changes in wind direction can simply remove the effect of a source from a sampling location.

12.2 AIR mOnItORInG StRAteGyGuidance on the occupational air monitoring required under CAR is described in HSG248 (HSE, 2005). The remainder of this chapter refers to ambient air monitoring to inform soil risk assessment and to demonstrate the protection of the public and the local community.

The air monitoring strategy needs to be specific to the site. It will be informed by the CSM, including the desk study and the results of any surveys of ACSs. It will depend on the purpose of the monitoring, the



location of the site, its use and the activities (or proposed activities) on the site, the nature and extent of any asbestos contamination and ground and weather conditions.

The strategy should produce data that can be related, either directly or indirectly, to the concentration of airborne asbestos in the breathing zone of potential receptors.

The strategy should be proportionate (the need for ambient air monitoring during redevelopment can be driven as much by community relations as risk assessment requirements). For example, little or no air monitoring would be necessary to demonstrate the protection of the public in remote sites but monitoring may be required if the site is in a residential setting. Low concentrations of chrysotile asbestos in bonded material in undisturbed soils would require much less (if any) air monitoring compared to the disturbance of high concentrations of amphibole asbestos in friable materials. Weather conditions are likely to be important in determining the extent of asbestos fibre release.

In the absence of UK policy regarding environmental levels of asbestos, sampling methods and procedures should be sufficiently sensitive to discriminate between background asbestos concentrations in ambient air (see Section 6.3) and any low level exposures from ACS that could cause a significant risk to health. Background concentrations in outdoor air were reportedly 0.0001 to 0.00001 f/ml in the 1980s and may have fallen since (Section 6.3.1). So, the air monitoring methods selected for ambient monitoring need to achieve detection limits of 0.00001 fibres/ml or less. Similar detection limits are recommended for indoor air monitoring due to the long exposure durations involved. For activity-based environmental monitoring and occupational health monitoring, detection limits of 0.0001 and 0.001 fibres/ml, respectively would be acceptable.

In addition, the methods selected should discriminate between asbestos and non-asbestos fibres (eg organic fibres, MMMF or gypsum) and between the different asbestos minerals (or at least amphibole and chrysotile fibres).

12 .2 .1 Ambient air monitoringAmbient air monitoring for asbestos associated with ACSs requires secure monitoring points that are accessible to operatives. The locations should be selected according to the nature of the site and the aim of the assessment. Normally, monitoring points would include locations representing sensitive receptors. Also, there is often value in measuring concentrations unlikely to be affected by the site in question but within the same general area to help assess whether any airborne asbestos detected may be from another source or local background levels. Sampling periods are normally defined by the required detection limit – longer periods giving lower detection limits (Box 12.1). In the case of ambient air, the necessary sampling period for a sample can be up to one week to detect even a doubling or tripling of ambient airborne asbestos concentrations. Concentrations at the monitoring point depend on the weather conditions, in particular, wind direction and rainfall, and soil moisture. Ideally, monitoring should represent long-term average conditions (ie over 12 months) to allow for weather and activity variations but this is rarely practical. In the absence of such data, several weeks of sampling during a dry period may suffice (although it is not always possible to arrange). Exposure calculations based on this measurement data need to take account of the proportion of the year that dry weather prevails and the site activities both during sampling and in normal years in order to predict a typical annual airborne asbestos concentration.

Box 12.1 Outdoor air monitoring alongside various rights of way in Cambridgeshire

As well as detailed records of sampling periods, flow rates and sample maintenance, records should be kept of weather and ground conditions during the sampling period, activities on the site suspected of containing asbestos and other relevant activities such as construction or maintenance work on utilities.

Standard air samplers were run for 24 hours/day over a seven day period. To achieve this, the air pumps were powered by car batteries that were changed at regular intervals. Samples collected over four weeks provided a basis for estimating annual average concentrations from modelling the observed dependence on the weather conditions


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The results of this type of exercise provide valuable evidence on airborne concentrations and the potential for exposure. However, they only reflect likely exposure during the sampling period. For example, if the ground was wet during air sampling, asbestos emissions will be lower than for drier conditions. Such measurements also take no account of the future disintegration of ACMs within the soil.

12 .2 .2 Indoor air monitoringAsbestos can be ‘tracked back’ from outdoor soils to indoor environments inadvertently on shoes, clothes and pets and result in exposure via indoor air.

Surface dust sampling (see Section 11.3.4) can only indicate a potential for indoor exposure to occur. Indoor air monitoring can provide direct measurements of indoor airborne fibre concentrations. Sampling inside a building is made relatively easy by the availability of mains power and dry conditions. Static sampling in occupied areas, preferably close to the route outside, for periods of one or two days will provide substantial amounts of information. However, general household activities produce a wide-range of non-asbestos fibres (skin fragments, gypsum, paper fibres and textile lint etc). SEM or TEM techniques are required if false positives are to be avoided.

To replicate normal exposures, samples can be collected while typical activities are conducted (such as vacuuming, dusting, disturbing and beating curtains and soft furnishings). An appropriate method statement and risk assessment would be needed and any personnel involved provided with appropriate RPE and PPE etc. However, it should be noted that the high levels of general household dust generated by such activities, particularly in residential properties, may overload the samplers. If necessary, sample preparation procedures can remove organic dust and organic fibres and some relatively soluble minerals before analysis by electron microscopy. These sample preparation procedures are complex but minimise the need to reduce the sampling volume and maintains measurement sensitivity.

Indoor asbestos in air measurements may be a direct indication of the importance of ACS as a source of indoor air contamination but the measurements need to be interpreted carefully. Their value is limited if the fabric of building contains ACMs, so before any such monitoring, a survey should be conducted to identify alternative sources of asbestos. Indoor air monitoring only informs the assessment of current risks as it cannot account for future degradation of ACMs that may increase the risks of fibre release from ACSs or changes in behaviour that may lead to increased soil tracking.

Indoor air monitoring is only possible where buildings are already present. This means it has limited use, for example, under redevelopment scenarios where houses have yet to be built.

Indoor air monitoring as a component of a Part 2A assessment may prove difficult in residential properties where owner consent is not forthcoming or where the disruption to residents is considered unacceptable etc. However, such issues can often be overcome by effective communication with residents (see Chapter 16).

12 .2 .3 Activity based samplingActivity based sampling (ABS) is the preferred method for characterising the release of airborne asbestos fibres from soils in the US (US EPA, 2008). However, there are no established procedures for its use in the UK. Its use may be restricted if it is considered by HSE to breach CAR (by not preventing asbestos exposure ‘as far as is reasonably practicable’). However, personal monitoring is conducted during the site investigation (ie digging and soil sampling) for occupational hygiene purposes. The resulting data may be of use in lieu of actual ABS data. It is strongly recommended (except in unusual circumstances) to consult the HSE before undertaking any activity-based sampling.

ABS involves measuring airborne asbestos fibre concentrations during simulated activities involving ACSs. Such activities may include outdoor recreational activities (children playing, walking, gardening etc) or outdoor work activities, such as site development or sample collection. Samples are collected using personal monitoring methods (ie the sampler is worn by the receptor and air is sampled in the individual’s breathing zone). A risk assessment should be carried out to determine the level of protection



needed (ie RPE and PPE) for the sampling personnel and how the public can be excluded from the area during sampling.

Sample periods are much shorter than for indoor or ambient air monitoring, so the detection limits are higher. However, the concentrations of airborne asbestos generated by the activity may be significantly higher than background levels.

As with other forms of air monitoring, ABS needs to be conducted when the soil is dry and dusty. However, unlike other forms of air monitoring, it may be possible to tent and dry the area before sampling, if it is specifically established that this is not a breach of CAR.

Activity-based sampling is potentially a powerful tool for assessing exposure from ACSs. However, the activity-based sampling should be undertaken on an area that is representative of the site. The results apply only to the conditions at the time of sampling, the measured concentrations will be particularly susceptible to ground conditions and the measurement does not take account of any future degradation of ACM matrices.

Summary

�� where ACSs are present, air monitoring may provide valuable data that can support a robust soil risk assessment

�� air monitoring provides the only direct measurement of potential exposure, but the context of any measurements needs to be evaluated carefully to understand how, or if, it is representative of likely exposures

�� depending on the objectives, monitoring may be of outdoor air or indoor air (where soil-derived asbestos may have been tracked back into buildings)

�� activity-based sampling is widely used in the US, but it may not comply with CAR in cases where asbestos fibres are expected to be present

�� any monitoring and analysis must be conducted in-line with CAR and by a suitably accredited organisation

�� ambient monitoring and analysis also needs to be appropriate to the data requirements (eg limits of detection and quantification). This requires sampling methods different to those generally used for occupational hygiene and described in HSG248 (HSE, 2005)

�� electron microscopy methods (ie SEM or TEM) are generally required to achieve the specificity and low detection limits required for monitoring environmental situations

�� PCOM is prone to producing false positives as there is no discrimination between fibre types. It is suitable for occupational health monitoring and compliance monitoring under CAR and may suffice for any activity-based sampling and for perimeter monitoring as a first check that control measures for airborne dust and asbestos have not failed

�� detailed discussions with subcontractors will be needed to confirm that they can achieve the required analytical specifications as such methods are not commonly requested.


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13 exposure estimation

The risks to human health from airborne asbestos fibres are related to cumulative exposure, which is dictated by the magnitude and duration of exposure(s). Cumulative exposure is expressed in fibre/ml.hours or as fibre/ml.years. Cumulative exposure estimates should represent all exposures/activities from both indoor and outdoor air suggested within the CSM. Exposure estimation involves measuring, or predicting, potential airborne fibre concentrations, estimating likely exposures during current and foreseeable activities on a site and then calculating the additional total cumulative exposure that the receptor may receive as a result of the asbestos present on that site.

Exposures are dependent on many site-specific factors and so should be calculated based on the sum of information collated during the PRA and field investigations. As a minimum, this should include:

�� details of the current or future land use, including likely receptors

�� the extent, location and depth of asbestos contamination

�� the type, form, condition and concentrations of asbestos and ACMs in soils.

The remainder of this chapter discusses estimating the cumulative exposure as part of a human health risk assessment for a defined area of asbestos-impacted land for the purposes of either planning or Part 2A. The cumulative exposure can then be used to assess the risks of the receptor developing lung cancer or mesothelioma in the future (Chapter 14).

13.1 pRInCIpleS Of expOSuRe ASSeSSmentUnlike other common contaminants, the risks associated with ACSs result from the potential to release airborne fibres. So, an assessment cannot be conducted simply in terms of soil concentrations unless there is almost no or a huge amount of asbestos present. To be scientifically valid, the assessment should be based on the resulting airborne fibre concentration.

A fundamental component of exposure assessment is to estimate, measure or predict the concentrations of airborne asbestos that could arise from the ACSs on site. While each has limitations, this guide presents a ‘toolbox’ of methods and techniques that can inform this process.

The most direct way to assess airborne concentrations is by direct measurement of asbestos fibre in air (Section 12.2). However, such measurements represent a snapshot and so do not necessarily reflect changes over time (such as weather, eg dry, wet, damp, disturbance activities, wind strength, deterioration of ACM and direction, location of receptors). If suitable measurements are available, the influence that such changes may have on long-term exposures should be taken into account.

Site investigation data will provide details of the concentration and extent of asbestos contamination within the soils - only if specialist testing has been conducted will any information on air concentrations be available. Although the concentration in soil cannot be used directly to assess risks, predictive modelling can be used to estimate potential airborne fibre concentrations.

In most cases air monitoring alone will not be able to provide robust data on likely long-term exposures due to the technical difficulties in making the required measurements (Section 12.2).

So, the only feasible option in most cases is to use predictive modelling approaches (while taking account of its limitations).

AimThis chapter summarises the currently available methods for estimating potential exposures to airborne asbestos fibres derived from ACSs. It is necessary to estimate the potential airborne asbestos concentration that may be released by ACSs in order to then estimate the potential risks.



13 .1 .1 Local climate and other considerationsAs airborne fibres are only likely to be released when the soil surface is dry and dusty, the local climate is an important consideration in any prediction. The length of time that soil is dry and dusty depends on prevailing rainfall and temperature as well as numerous other factors such as soil type, vegetation cover, organic matter content, porosity, capillary action and depth to groundwater.

Rainfall varies greatly across the UK, with extremes being in NW Scotland where the annual rainfall is around 4000 mm and in East Anglia where the average annual rainfall can be less than 600 mm. However, the number of dry days may be a better indicator of potential fibre release. Data on daily rainfall is available since 1931 for different regions of the UK from the Met Office Hadley Centre Observation Data (see Useful websites). Where downwind or off-site receptors may be affected by wind-blown fibres, site-specific variation in wind speed and direction would also be an important consideration.

Asbestos fibres can also only be released from exposed soil – release will be strongly inhibited by vegetative cover and prevented by any hard surfacing.

No matter how airborne fibre concentrations have been measured or estimated, the impact of local climate and surface cover on likely exposures at the site should always be considered.

13.2 CAlCulAtInG expOSuReS And CumulAtIve expOSuRe

The exposure scenario needs to be defined that lists and describes, in detail, all events during which the receptor is reasonably likely to be exposed to airborne asbestos deriving from the soils at the site. Such events may occur repeatedly over a number of years, there may be more than one type of event and exposures may occur both indoors and outdoors. The exposure scenario should include all events and exposures, which may include outdoors activities that disturb soil and asbestos or disturb surface ACMs, outdoors exposure to windblown dust, indoors activities that redispersion tracked in contamination (eg vacuuming, dusting, DIY). Any major errors in the exposure scenario will result in under or over estimation of the cumulative exposure.

The exposure scenario should also include all other factors likely to affect exposures at the site, such as local climate, vegetative cover and hardstanding (ie extent of exposed soil) and the potential for ‘track back’ resulting secondary exposures indoors. The exposure scenario may also need to discriminate between passive and vigorous activities as the levels of airborne asbestos disturbed will be different – exposure from many passive activities (sitting inside, walking in the garden) may be insignificant compared with vigorous activities (vacuuming carpets or digging in the garden).

An assessment of the potential risk should consider all the relevant exposures that the receptor is reasonably likely to experience during the entire period they are exposed to site-derived soils. This overall exposure is known as the ‘cumulative exposure’.

Exposure and cumulative exposure are normally expressed in fibre/ml.hours or as fibre/ml.years. As the lung cancer and mesothelioma models (see Chapter 14) are based on occupational exposures, converting from hours to years needs to be based on the number of hours in an occupational working year, generally taken to be 48 weeks of 40 hours (sometimes rounded to 2000 hours).

Exposure from each event in the exposure scenario is the product of the airborne asbestos concentration during the event and the period of time that the exposure lasts. Each event should be considered separately. The annual exposure (Ei) from each event, i, can be expressed in fibre/ml.hours as:

Ei = Ci × Fi × Ti


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whereCi = the estimated concentration (f/ml) for the eventFi = the frequency of the event per yearTi = the period of time that the event lasts in hours

The frequency and period of the event will depend on the exposure scenario. For example, if the site is woodland being restored for public access, exposure is likely to be infrequent and of short duration. By contrast, in domestic situations some people spend several hours a day in their garden. It should also be remembered that a high proportion of time is spent indoors by most people, particularly young children and the elderly.

Cumulative exposure for each event is the sum of the relevant annual exposures. So, the cumulative exposure for event i, CEi, is the annual exposure for the event multiplied by the number of years that the event is predicted to occur.

CEi = Ei × Yi

whereYi = the number of years that exposure event i will occur.

Where site-specific information is not available, or where general assumptions are appropriate, the standard UK exposure durations (years), exposure frequencies (days per year) and occupancy periods (hours per day), such as those presented by Jeffries and Martin (2009), may be appropriate. However, the standard receptors (eg the 0 to 6 year old female child for residential scenarios) should not be relied upon when assessing asbestos. The exposure scenario should instead contain realistic assumptions regarding who is likely to be the critical receptor and exposure duration (in some cases this may be an entire lifetime). For example, exposure during childhood is generally regarded as more serious than exposure in later life (see Section 14.3).

Where the exposure scenario describes more than one type of event, the total cumulative exposure (CEtot) is the sum of the cumulative exposures for all relevant events (ie CEtot = ∑CEi).

Assessing the potential risks associated with the derived cumulative exposure is described in Chapter 14.

13.3 uSe Of OutdOOR AIR mOnItORInG dAtAAn example of how air monitoring data may be used to calculate exposure is presented in Box 13.2.

Where sites are under development and asbestos in soil is encountered, occupational air monitoring is often undertaken to demonstrate that dust suppression and other control measures are being effective. Measurements taken under these conditions do not represent concentrations of airborne dust and fibre that may arise post-development (eg large-scale soil disturbance may occur but dust suppression and other control measures are usually in place during construction) and should not be relied upon in exposure estimation.

Where relevant airborne asbestos fibre concentration data is available, this can be used directly to estimate exposure. However, air monitoring can only measure concentrations under the conditions at the time of sampling. Assumptions and/or modelling will be required to take account of changes in condition (eg future degradation of ACM, weather, wind strength and direction) or changes in activities.

Any assumptions, estimations or modelling used needs to be fully explained and documented. In the UK, one of the significant practical difficulties can be in arranging for air monitoring under conditions when fibre release is most likely (eg hot and dry and during disturbance activities). Where the data collected does not represent such conditions, extrapolation is likely to be required to account for these factors. This is particularly challenging if conditions remain wet during sampling and measurements are below detection limits (which is common) – it is possible to extrapolate down to below detection limits but not from below detection limits.



For example, the use of airborne asbestos concentration measurements may need to consider issues such as:

�� how closely the measured airborne fibre concentrations are likely to represent the actual exposure (were the activities typical, more vigorous or less vigorous, creating more or less soil disturbance than usual?)

�� what were the weather and ground conditions during monitoring?

�� the variation in the behaviours of potential receptors (eg a small number of residents may be keen gardeners but most will not be –was the active gardener represented in the measurements?).

Box 13.1 Rights of way and byways in Cambridgeshire

Box 13.2 Example calculation based on air monitoring data

13.4 uSe Of publIShed SOIl-tO-AIR RelAtIOnShIpSData on such relationships have been published by RIVM (2003), and Addison et al (1988).

As described elsewhere in this guide, Addison et al (1988) published data on relationship between the release of asbestos fibres (in units of f/ml per mg/m³ respirable dust) and asbestos-in-soil concentration (per cent by weight) for dry soils (0% moisture). The relationship applies over a wide range of concentrations of asbestos fibres in soil, although there is some uncertainty at concentrations at or below 0.01 per cent. These findings, in conjunction with a number of assumptions, can be used to derive cautious estimates of the potential release of airborne fibres where:

�� the site soil is similar to the ‘clay’, ‘sandy’ or ‘intermediate’ soils prepared by Addison et al (note that made ground was not included)

Air monitoring data was used to estimate exposures in the assessment of potential risks to residents posed by rights of way and byways in Cambridgeshire that had been surfaced with asbestos cement wastes (Jones et al, 2005). The rights of way were regularly used by small numbers of vehicles (ie residents’ vehicles and service vehicles). So there was regular disturbance and sampling of airborne asbestos concentrations was possible.

Sampling for airborne asbestos concentration was undertaken for seven day periods, over four weeks during September. The weather conditions over the period ranged from mostly dry days with sunshine to mostly wet days with much less sunshine.

It was possible to develop a simple model of the effect of weather conditions to extrapolate from the four week sampling to estimate annual average concentrations of asbestos in air.

Activity-based sampling has been conducted in back gardens at a retirement village during gardening and sweeping activities during a hot spell in the summer. The airborne fibre concentration measured was 0.005 fibres/ml (Ci). Regional meteorological data support the assumption that such dry conditions are encountered for 15 days a year. It is reasonable to assume that the retired residents may spend one hour a day on average gardening. So, assuming that an exposure event is only possible on dry and dusty days, Fi can be assumed to be 15 per year, and an exposure event could only last a maximum of one hour (Ti). So annual exposure during gardening (Ei) may be:

Ei = Ci × Fi × Ti

Ei = 0.005 f/ml × 15 per year × 1 hour = 0.075 fibre/ml.hours/year

Assuming that residents typically live at the retirement village for 12 years (Yi), the cumulative exposure (CEi) during gardening may be:

CEi = Ei × Yi

CEi = 0.075 fibre/ml.hours/year × 12 years= 0.9 fibre/ml.hours= 0.9/2000 fibre/ml.years= 0.00045 fibre/ml.years

The uncertainties that would need to be considered may include whether grandchildren may spend time with grandparents in the gardens, and whether they would be liable to disturb soil dust in playing. Children aged 5 are 50 times more at risk from a given exposure than adults aged 55 (Hodgson and Darnton, 2000) (see Chapter 15). It is also important to consider the extent to which asbestos concentrations in the soil may vary between gardens. Information on asbestos in soils (quantitative concentrations or qualitative prevalence) may inform the assessment of differences between gardens.


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�� measured soil concentrations of asbestos fibres (per cent) are available

�� the likely soil dust in air concentrations (mg/m3) can be estimated or measured.

Box 13.3 Example calculation based on predictive modelling (after Addison et al, 1988)

The Addison et al (1988) data was gathered under controlled laboratory conditions, which reduces the variation inherent in site measurements (ie dilution rates, weather, wind speeds and directions). The predictive modelling approach can also be very flexible. By using appropriate assumptions, it can take account of:

�� different types of activity

�� different climates and soil moistures

�� different asbestos type(s) (eg bound ACM, friable ACM or free fibres)

�� future changes in the condition of ACM due to weathering, degradation etc

Predictive modelling approaches are the only feasible way to estimate this expected future release from friable ACMs that will continue to weather in soils or be physically degraded by site activities.

However, the Addison data involved mixtures of dried and milled soils and pure asbestos fibres (not ACM) under disturbance conditions more extreme than are likely to be encountered at most sites and “moderately aggressive in comparison to other methods” (page 19 of Addison et al, 1988). The resulting predictions are therefore likely to be cautious, and careful consideration should be given to all assumptions and inputs if an overly conservative estimate of airborne fibre concentration is to be avoided in ‘real world’ conditions. The relevance of predictions made using such predictive modelling should be clearly established on a site-specific basis by the risk assessor, including a consideration of differences in soil type, form of ACM etc.

An example of how predictive modelling can be used to estimate airborne concentrations is presented in Box 13.3. However, this example relies entirely on the data from a single study.

13 .4 .1 Appropriate soil concentrationThere is likely to be considerable variation within the reported asbestos in soil concentrations at any given site. The implications of such variation should be carefully considered before selecting the concentration at which to predict an airborne concentration (eg minimum, maximum or some estimate of central tendency). Careful consideration should be given to the implications of any value selected

The results of Addison et al (1988) were used to estimate the likely asbestos in air concentration based on measurements of concentrations of asbestos in representative soil samples taken from a single domestic garden. The asbestos concentration in soil was estimated to be 0.1 per cent amosite. The soil was clay.

The predicted normalised fibre concentration from the graph was 0.1 f/ml per mg/m3. The concentration of soil dust during gardening activities in dry and dusty conditions was estimated at about 100 μg/m3 (ie 0.1 mg/m3), based on ambient urban dust levels and ART modelling of shovelling dry powders. Therefore, an airborne fibre concentration during such activities in dry and dusty conditions was estimated to be 0.01f/ml (Ci), and assumed to be insignificant at other times. Residents were assumed to conduct activities in gardens under dry and dust conditions for an average of 90 hours per year (Fi.Ti).

So [annual] exposure would have to be:

Ei = Ci × Fi × Ti

Ei = 0.01 f/ml × 90 hours/year = 0.9 f/ml.hours/year

For a young child this would amount to say Yi = 6 years so cumulative exposure would be

CEi = Ei × Yi

CEi = 0.9 f/ml.hours/year × 6 years = 5.4 fibre/ml.hours = 5.4/2000 fibre/ml.years= 0.0027 fibre/ml.years

Monitoring for asbestos in air provided data to support the assumption that concentrations would be insignificant under Part 2A in wet or damp weather/soil conditions.



with respect to the exposure scenario. For example, the use of mean soil concentration implies that the receptor will be equally exposed to fibres released from all the soils at the site. Careful zoning of the site, including a consideration of depth, may be required to adequately reflect likely exposures.

The type and condition of any ACM should also be considered. Predictive modelling assumes that the soil concentrations used represents free asbestos fibres in the soil (or ACM liable to release free fibres in the foreseeable future). In contrast, asbestos cement is expected to deteriorate slowly in soils – it has been shown to release few fibres by RIVM (2003) in real situations and by Burdett (undated) in laboratory tests. As a result, it may be appropriate to exclude such durable materials when predicting airborne fibre concentrations. Robertson et al (2011) excluded durable ACM in predictions of fibre release.

13.4.2 Derivingsoil-dustinairconcentrationsThe Addison et al (1988) data was reported relative to respirable dust concentrations (ie f/ml per mg/m3 dust). So, the concentration of airborne soil dust (eg PM10) used in the predictive modelling will have a direct effect on the estimated airborne concentrations of asbestos fibres. Great care needs to be taken in selecting, and justifying, an appropriate value of airborne dust that is consistent with the exposure scenario as an overly cautious value will result in unrealistically high predictions of airborne asbestos fibres. However, the difficulty in identifying a defensible value should not be underestimated.

Respirable dust concentrations can be measured on-site (under relevant conditions), based on literature values for activities similar to those being considered, or based on measurement at other similar sites. In addition, predictive models such as the ART model (an occupational dust exposure tool) can give indicative concentrations of soil dust in air for some activities (see Useful websites).

While the ART user guide points out that the model is not calibrated for asbestos fibres per se, it can be used to predict levels of dusts generated from soils. Robertson et al (2011) used both site measurements and ART predictions in estimating the likely concentrations of soil dust in air during activities in domestic gardens.

13 .4 .3 Friability of different ACMsTests by the HSL (Burdett, undated) have been used to compare the release of free fibres from different ACMs (see Section 9.6.1). Such data provide a basis for making allowance for the type of ACM in so far as it affects the primary release of asbestos fibres. The effect of degradation of ACMs over time in soils may require judgment.

In order to use this information, the asbestos content in soil samples needs to be reported in terms of the approximate amount of asbestos within each category of ACM found (eg loose insulation, AIB, textiles and asbestos cement). Currently, such details are often not reported by laboratories.

13.5 uSe Of ‘pOtentIAl fIbRe ReleASe’ teStSSoil testing for the potential fibre release is not widely available in the UK (see Section 11.3.3). If such tests become commercially available, they could be used to directly measure potential fibre release from soil samples under ‘worst case’ conditions (ie dry, dusty and vigorously disturbed soils). If sufficient representative samples were tested, such measurements are likely to better reflect the soil type and type/concentration of asbestos present etc than values derived by predictive modelling. However, they may not be representative of the long-term release of fibres if substantial degradation of the ACMs is anticipated in the future.

As such tests would most likely report data relative to respirable dust concentrations (eg f/ml per mg/m3 dust), the issues discussed in Section 13.4.2 would still be relevant.

An example of how such data could be used to estimate exposure is presented in Box 13.4.


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Box 13.4 Hypothetical example of the use of ‘potential fibre release test data

13.6 AtmOSpheRIC dISpeRSIOn And dIlutIOnIn indoor air, dispersion and dilution are likely to be negligible and airborne asbestos fibres can remain suspended for significant periods.

However, where the receptor may be outdoors some distance from the ACS, it is important to allow for dispersion and dilution. For example, HSE (1976) estimated that asbestos concentrations at a distance of 20 to 30 feet (ie 7 m to 10 m) from construction processes are about one-tenth of the concentration at the activity.

Atmospheric dispersion models may be used to estimate potential exposures in such situations. For example, where on-site measurements close to a source of exposed asbestos fibres at a derelict site detect airborne fibres released by wind erosion, the potential exposures of off-site receptors downwind could be estimated using atmospheric dispersion modelling. All aspects of any modelling would need to be justified and documented, including input parameters relating to local climate and prevailing wind direction etc. A similar approach was used to model dispersion of historical emissions from an asbestos factory in Leeds to support assumptions relating to the attenuation of airborne asbestos with distance (Cherrie et al, 2005).

There are no specific models for asbestos assessment. However Swartjes and Tromp (2008) described the use of PLUIM-PLUS, which was designed for gases, vapours and dusts (PM10) but that has reportedly now been partially validated for asbestos fibres. The type and selection of model will depend on the site and the pathways likely to result in human exposure, but given the large uncertainties in determining the rate of release of asbestos from ACS, relatively simple models of dispersion may be sufficient.

13.7 uSe Of IndOOR expOSuRe InfORmAtIOnThere may be several lines of evidence that help assess whether the presence of asbestos in soils is likely to lead to exposure indoors including:

�� Is track back of contamination likely based on site observations?

�� Is there evidence of asbestos in surface dust indoors, and if so how prevalent?

�� Is data available on the concentration of asbestos fibres in indoor air?

There is some concern regarding long-term asbestos exposure for sportsmen at a playing field. Ten surface soil samples were subjected to potential fibre release testing. The average result was 0.1 f/ml per mg/m3 dust. Personal dust monitoring of home players was conducted throughout the season and suggested average airborne soil-dust concentrations of 25 μg/m3. This measurement is assumed to be representative of the local climate and account for grass cover. Based on these measurements, the annual average airborne fibre concentration encountered during play was estimated to be 0.0025 fibres/ml (Ci).

The club plays 15 home games per year and runs a maximum of 35 training sessions (90 minutes). So, Fi can be assumed to be 50 per year, and Ti is 1.5 hours. Assuming attendance at all games and training, the maximum annual exposure for a club player (Ei) may be:

Ei = Ci × Fi × Ti

Ei = 0.0025 fibres/ml × 50 per year × 1.5 hours = 0.1875 fibre/ml.hours/year

Club members are typically only active players between the ages of 19 and 29. If a typical value for Yi is assumed to be 10 years, the cumulative exposure (CEi) may be:

CEi = Ei × Yi

CEi = 0.1875 fibre/ml.hours/year × 10 years= 1.88 fibre/ml.hours= 1.88/2000 fibre/ml.years= 0.00094 fibre/ml.years



A consideration of potential indoor exposures may be critical to the overall cumulative exposure, because of the extended exposure frequencies and durations potentially involved. For example, in a residential scenario, a 0 to 4 year old child is expected to spend 23 hours per day 365 days per year inside the home (Jeffries and Martin, 2009). So, exposures at very low concentrations indoors (well below 0.01 f/ml) can result in significantly elevated cumulative exposures. For example, exposure of such a child at an average concentration of 0.0003 fibres/ml would give a cumulative exposure of 10 fibre/ml.hours, which is equivalent to 0.005 fibre/ml.years. As shown in Chapter 15, if the exposure involved amphibole asbestos it would represent a substantial lifetime risk (eg about 66 in 100,000 for crocidolite).

The presence of asbestos in settled dust, such as that inside homes, outbuildings, sheds or offices, suggests that airborne asbestos fibres have been present in indoor air, and so provides evidence for potential exposure. However, quantifying such exposure may require measurement of indoor airborne fibre concentration. Re-suspension of asbestos is difficult to model as it depends on a large number of factors including the surface, the nature of the asbestos fibres, the nature of other dust present and the nature of the disturbance and humidity. These problems are illustrated by the variation in experimental measurement of re-suspension factors for asbestos, which range from 10-2 to 10-8 (eg Fowler and Chatfield, 1997). Where asbestos is present in settled dust, the need for indoor air monitoring should be considered in order to quantify the potential exposures.

Where indoor air monitoring data is available, it can be used directly to calculate exposures in a similar manner to outdoor air monitoring data (Section 13.3). Exposures should be calculated based on the durations (years), frequencies (days per year) and occupancy periods (hours per day) for indoor exposures described in the exposure scenario. However, where there is evidence of asbestos fibres indoors (either in settled dust or air monitoring), it should always be considered whether this relates to ACM within the fabric of the building, or other potential sources, rather than from nearby ACSs. Exposures due to other sources would normally be excluded from an assessment of risks from ACSs.

13.8 RepORtInGFull, transparent reporting of the exposure estimation process and findings, including disclosure of the uncertainties involved and the rationale supporting the use of any models and all assumptions is essential.

The level of detail required should allow a competent reader to replicate the estimation process. The information that needs to be reported in an assessment of exposure would include:

�� the types of asbestos found

�� the concentrations of ACM fragments and free fibres in soils

�� the state of ACM and its likelihood to degrade to fibres

�� exposure pathways (is indoor exposure significant?)

�� the locations sampled (soil samples and any air monitoring etc)

�� the distribution of asbestos contamination on the site

�� locations where asbestos in air concentrations are observed or expected

�� exposure scenario(s) for which cumulative exposures have been estimated including:

�� who the critical receptor is

�� the age at which exposure started

�� the exposure duration and exposure frequency

�� how cumulative exposures (fibre/ml.years) were calculated

�� what cumulative exposures (fibre/ml.years) were predicted.


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Summary

�� an exposure scenario should be defined that describes all events reasonably likely to result in exposure of the receptor to asbestos from the soil and should include any factors likely to have a significant influence on such exposures

�� estimates of the airborne asbestos concentration the receptor may encounter are needed for quantitative assessment of risk relating to ACSs. Estimates can be based on air monitoring, ‘fibre release potential’ tests or from soil concentrations using predictive modelling. Because each approach has strengths and weaknesses, a lines of evidence approach involving more than one is usually required for robust risk estimation

�� representative air monitoring data will be a valuable line of evidence at most sites but it should be interpreted with care as it may underestimate future exposures dependant on the future land use and the conditions under which the monitoring occurred

�� published information on the soil-to-air relationship provides normalised airborne fibre concentrations relative to soil dust in air concentrations. In order to estimate actual airborne fibre concentrations, the likely respirable soil dust concentration needs to be estimated based on measurements or other predictive tools

�� a cumulative exposure to asbestos from the ACS can be derived as the sum of all events listed in the exposure scenario based on the airborne asbestos concentrations, frequency and duration of each event

�� the method used to estimate exposure, inherent limitations and the exposure scenario considered should all be clearly presented in any report.



14 Risk estimation and evaluation

Any decision regarding the acceptability or otherwise of the risks posed by ACSs requires the agreement of the relevant regulators, in most cases this will be the local authority.

In order to interpret the acceptability and significance of exposures to airborne asbestos (estimated in the previous chapter), it may be necessary to make quantitative estimations of the likely extra lifetime risk that may result from exposure to the ACS at the site. For example, under planning the risk will need to be low enough to ensure the site is suitable for its intended use, while under Part 2A the possibility of significant harm should be a significant one (ie a ‘significant possibility of significant harm’).

The Part 2A Statutory Guidance (Defra, 2012a) advises that “The uncertainty underlying risk assessments means there is unlikely to be any single ‘correct’ conclusion on precisely what is the level of risk posed by land, and it is possible that different suitably qualified people could come to different conclusions when presented with the same information. It is for the local authority to use its judgement to form a reasonable view of what it considers the risks to be on the basis of a robust assessment of available evidence”. For Part 2A, the local authority uses its judgement while having regard to the broad objectives of the regime and that the starting assumption should be that land does not pose a ‘significant possibility of significant harm’ unless there is reason to consider otherwise.

14.1 quAlItAtIve RISK evAluAtIOnIn cases where there is no pathway or no receptor then the decision not to remediate can be taken on the basis of qualitative risk evaluation based on the CSM.

In some cases, the decision to remediate (either localised areas or the site as a whole) will be obvious even without quantified estimates of the potential risks. This may include sites where public concern makes remedial intervention a political necessity or where gross contamination is present at or near the surface and exposure is certain. However, even in these cases, there may be a need for a quantitative assessment of risk to determine the remediation criteria and/or the extent and volume of material that requires treatment or disposal.

If the qualitative risk assessment shows that there may be a risk of concern, then a quantitative risk assessment will be required (Environment Agency, 2004).

14.2 GeneRIC quAntItAtIve RISK ASSeSSmentA generic quantitative risk assessment would involve selecting or deriving a generic assessment criterion (GAC), such as a soil guideline value (SGV), which could be used to screen out low risk substances. If the levels of asbestos in soil at a site fell below the GAC then the level of risk would not be of concern. Deriving a GAC is a function of the fate, transport and toxicological properties of the contaminant and of the exposure scenario being considered (Nathanail et al, 2009).

In the case of asbestos in soil there is no published SGV or C4SL and none are in preparation. Indeed, agreement has yet to be reached in the UK on an appropriate toxicological criterion on which such a GAC could be based (see Section 5.7).

AimThis chapter outlines how the exposure to asbestos (estimated as in the previous chapter) can be used within exposure-risk models to predict the lifetime risk from such exposure and how that risk can be evaluated under different legal contexts (see Chapter 3).


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Based on current knowledge, it is believed that a scientifically defensible UK GAC for asbestos in soil cannot be developed or imported. While the dose-response relationship for asbestos is relatively well understood and asbestos is known to be resilient in the soil environment, the transport properties are very poorly constrained – particularly the soil-to-air relationship (Chapter 9). Using generic fibre release data, such as that described by Addison et al (1988) simplistically to derive a GAC would result in either a non-precautionary value, which may result in undesirable residual risks to human health, or in an unhelpfully low assessment value.

Where qualitative risk assessment shows that there may be a risk of concern, a detailed quantitative risk assessment using exposure risk modelling is recommended.

14.3 detAIled quAntItAtIve RISK ASSeSSmentA detailed quantitative risk assessment can be conducted using predicted cumulative exposures associated with ACSs (Chapter 13) and risk prediction models. This approach allows the likelihood that such exposures would cause, or contribute to causing, asbestos-related diseases to be estimated. The risk is a function of the composition and quantity of fibres released from the soil, the exposure scenario and the critical receptor.

14 .3 .1 The basis for risk modellingAsbestos is unusual in that there is so much data on the relationship between exposure and the incidence of asbestos-related disease. The relationships between exposure to asbestos and both mesothelioma and lung cancer have been extensively explored in epidemiological studies of thousands of individuals who were exposed to asbestos in various work situations (eg mines, textile factories, friction product factories, and gas mask factories). The key studies (reviewed by Peto and Doll, 1985, and HEI 1991, and in meta-analyses by Hodgson and Darnton, 2000, and Berman and Crump, 2008) have shown:

�� clear links between the extent of cumulative exposure (eg expressed as fibre/ml.years) and the incidence and prevalence of disease (asbestosis, mesothelioma, and lung cancer)

�� differences in the potencies of the different types of asbestos (eg for mesothelioma crocidolite is more potent than amosite, which in turn is more potent than chrysotile)

�� latency periods of generally at least 20 and commonly 30 to 40 years or more between exposure and the onset of mesothelioma or lung cancer

�� risks increasing with extent of cumulative exposure

�� mesothelioma risk increasing strongly with time elapsed from first exposure, indicating a greater risk for those exposed early in life.

While there are substantial differences between individual epidemiological studies relating to study methods (how exposure has been assessed, statistical approaches etc), meta-analyses combine information from a substantial number of individual epidemiological studies. The various epidemiological studies and meta-analyses have confirmed the strong and robust causal link between asbestos inhalation and the incidence of lung cancers and mesothelioma following occupational exposure (HEI, 1991, Hodgson and Darnton, 2000, and Berman and Crump, 2008). For example, the meta-analysis of Hodgson and Darnton (2000) is based on 17 different epidemiological studies and thousands of individuals. Each epidemiological study generally examines the number of asbestos-related deaths over time in ‘cohorts’ of employees exposed to asbestos at specific mines or factories from countries including the US, Canada, UK, South Africa and Australia.

noteThe hazardous waste threshold (see Section 3.6), the value of 0.001 per cent mentioned in ICRCL (1990) (see Section 7.1), the clearance indicator threshold (0.01 f/ml) or the control limit (0.1 f/ml) are not appropriate generic criteria for assessing the long-term risks posed by ACSs. The use of criteria from other countries (see Chapter 7) would require an understanding of how and why they were originally derived, and justification as to why they are relevant to UK policy and guidance.



Each meta-analysis generally derives two equations (or models): one relating exposure to lung cancer incidence and the other exposure to the incidence of mesothelioma. The different meta-analyses have produced subtly different exposure-risk models for both lung cancer and mesothelioma risk associated with exposure to asbestos. The levels of disease predicted by all these models generally show a good correlation with the observed incidence of asbestos-related deaths.

It is possible to use the existing exposure-risk models to estimate the risks posed by ACSs in two ways. Both involve extrapolation beyond the observed epidemiological data down to the low levels of environmental exposure (see Section 14.5).

1 The first approach is to use the full mathematical models to predict risk explicitly for the exposure concentration, period duration and starting age of exposure. This approach requires a detailed understanding of the models and interpretation of the output. Unfortunately, software implementing the various models is not widely available and considerable effort and knowledge is required to develop in-house models from the descriptions in the scientific literature.

2 The other approach can be used without detailed knowledge of the full models. This approach draws upon tabulated risk summaries generated from the models to estimate risk at the relevant cumulative exposure (f/ml.years). This approach is illustrated in the following sections.

There are benefits in the detailed modelling, but the simple approach of extrapolating from risk summary tables may serve as a first indication of the likely level of risk. Where this indicates that risks may be of concern more detailed modelling may be required and expert input should be ensured.

14 .3 .2 MesotheliomaHodgson and Darnton (2000) present a useful risk summary of the indicative risks that would arise from different cumulative exposures. The summary for mesothelioma is presented in Table 14.1. These values assume exposure started at age 30, but can be adjusted for exposures starting at other ages using the factors presented in Table 14.2.

The risk estimates for mesothelioma for the amphiboles appear to be reasonably consistent between different models and can be regarded as generally well established. The risks for chrysotile (relative to those for the amphibole asbestos) are subject to ongoing dispute and debate in the scientific literature (see Section 14.4).


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Table 14.1 Risk summary statements for mesothelioma (after Table 11, Hodgson and Darnton, 2000)

Cumulative exposure (from age 30, over 5 years) mesothelioma – lifetime risk per 100 000 exposed

Fibre/ml.years Crocidolite Amosite Chrysotile

100 40000 (up to 2-fold uncertainty) 6500 (up to 2-fold uncertainty)

200 (up to 3-fold uncertainty)

10 4000 (up to 2-fold uncertainty) 650 (up to 2-fold uncertainty)

20 (up to 3-fold uncertainty)

1 650 (highest arguable estimate 1500 lowest 250)

90 (highest arguable estimate 300 lowest 15)

5 (highest arguable estimate 20 lowest 1)

0.1 100 (highest arguable estimate 350 lowest 25)

15 (highest arguable estimate 80 lowest 2) (highest 4)

0.01 20 (highest arguable estimate 100 lowest 2) 3 (highest 20)

0.005 About 10 (highest arguable estimate 55, lowest ‘insignificant’)

About 2 (highest arguable 15) insignificant

0.00007 Highest arguable becomes insignificant

0.000006 Highest arguable becomes ‘insignificant’

notes

1 Cumulative exposures (fibre/ml.years) are expressed in terms of occupational years, which are assumed to be about 2000 hours (see Chapter 13).2 The risks all apply to exposure starting at age 30, for exposures starting at younger ages the appropriate age-adjustment factor from

Table 14.2 should be applied.3 The risks assume that the cumulative exposure is received over five years. Where exposure scenarios involve exposures over longer

periods, a cautious estimate of risk can be obtained by assuming the total cumulative exposure is received over only five years in the table and applying the age-adjustment factor for the lowest relevant age. A more accurate estimate could be obtained by summing the risks for exposures received in successive five year increments and applying the relevant age-adjustment factor to each.

4 The term ‘insignificant’ is used in a colloquial rather than legal sense by Hodgson and Darnton (2000).

In non-legal terms, Hodgson and Darnton described some risks (below 1 in 100 000) as “probably insignificant”. However, risks of mesothelioma are higher for exposure starting at a younger age. As a result, some of the cells in Table 14.1 where risks from exposure are described as “probably insignificant” may become significant where a given exposure starts at a younger age.

Table 14.2 Age adjustment factors for mesothelioma risk dependant on the age at which exposure starts (adapted from HEI, 1991)

Age at which exposure commencesfactor – to adjust risk from table 14.1

(taking risk as persisting for 60 years) (taking risk as persisting for 80 years)

0 2.8 6.6

5 2.7 5.2

10 2.6 4

15 2.5 3

20 2.1 2.1

25 1.5 1.5

30 1 1

35 0.6 0.6

40 0.4 0.4

45 0.3 0.3

50 0.2 0.2

55 0.1 0.1

note

It is normal practice to consider that risks persist for 80 years (Hodgson and Darnton, 2000). The values given for exposures at age below 20 reflect one of the uncertainties in extrapolating models to exposures at younger age. However, they make no adjustment for possible greater vulnerability of the young.



14 .3 .3 Lung cancerThe risk summary for lung cancer presented by Hodgson and Darnton (2000) is shown Table 14.3. Again these values assume exposure started at age 30 for five years, however lung cancer risks are not age-dependant and so age adjustment factors are not required. As for mesothelioma, whether cumulative exposure occurred over five, 10 or 15 years etc has only a limited effect.

Table 14.3 Risk summary statements for asbestos-related lung cancer (after Table 11, Hodgson and Darnton, 2000). Risks below 1 in 100 000 were described by Hodgson and Darnton as ‘probably insignificant’

Cumulative exposure (from age 30, over 5 years) lung cancer – lifetime risk per 100,000 exposed

Fibre/ml.years Crocidolite Amosite Chrysotile

100 35000 (55000 to 25000) Same as for crocidolite 500, perhaps 3000, ‘in exceptional circumstances 10 000’

10 1500 (1000 to 2500) Same as for crocidolite 50, perhaps 300 ‘in exceptional circumstances 1000’

1 85 (20 to 250) Same as for crocidolite 2 perhaps 30, ‘in exceptional circumstances 100’

0.1 4 (<1 to 25) Same as for crocidolite ‘probably insignificant’, perhaps 3, ‘in exceptional circumstances 10’

0.01 1 to 3 (mesothelioma now dominant) Same as for crocidolite

notes

1 Cumulative exposures (fibre/ml.years) are expressed in terms of occupational years. An occupational year is assumed to be about 2000 hours (see Chapter 13).

2 The risks assume that the cumulative exposure is received over five years. Where exposure scenarios involve exposures over longer periods, a cautious estimate of risk can be obtained by assuming the total cumulative exposure is received over only five years in the table. A more accurate estimate could be obtained by summing the risks for exposures received in successive five year increments.

3 The term ‘insignificant’ is used in a colloquial rather than legal sense by Hodgson and Darnton (2000)

The risk summary statements produced by Hodgson and Darnton (2000) for asbestos-related lung cancer were based on an average pattern of smoking in the British population. The effect of asbestos exposure is generally accepted as being multiplicative with the effect of smoking, so the asbestos-related risks are actually much higher in smokers and lower for non-smokers.

Hodgson and Darnton (2000) stated that the estimates of lung cancer risk were based on British male mortality in 1997 when 9.5 per cent of male deaths at ages 40 to 79 were due to lung cancer. This represented an average for a population with a past pattern of smoking similar to that of older British men. In 1996, 23 per cent of men over 60 had never (or only occasionally) smoked and 25 per cent were regular smokers. They also stated that for lifetime smokers the asbestos-related lung cancer risk would be about double the levels in Table 14.3, and for non-smokers about one-sixth (if the interaction with asbestos is multiplicative) or about one-third if the relative risk is higher than in non-smokers as suggested by Berry et al (1985).

14 .3 .4 Overall excess lifetime riskThe overall excess lifetime cancer risk is the sum of the mesothelioma and lung cancer risks. Hodgson and Darnton (2000) commented that treating the two risks as independent is a satisfactory approximation unless estimated risks exceed 30 per cent.


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Box 14.1 Hypothetical worked example – risk from environmental exposure

14 .3 .5 Data requirements for predicting riskExposure-risk models for asbestos (HEI, 1991, Hodgson and Darnton 2000, and Berman and Crump 2008) show that the risks of asbestos-related cancer depend on the cumulative exposure (expressed in fibre/ml.years) and, for mesothelioma, on the time elapsed since exposure. These models assume non threshold behaviour. It is well recognised that there is uncertainty in extrapolating down to lower concentrations than the available data.

The data required to predict risk using the exposure-risk models include:

�� the estimated exposure, eg in f/ml.hours (as estimated in the previous chapter)

�� the type of asbestos

�� the duration of exposure

�� the age of the subject when exposure started

�� some models (eg HEI, 1991) require information on whether the exposed individual is a smoker.

For the approximate calculation of likely risk, it is possible with the acknowledged uncertainties entailed to extrapolate downwards from the summarised risk estimates from Hodgson and Darnton in Table 14.1. Then it is necessary to correct the risk to match with the approximate age at start of exposure (using factors from Table 14.2).

Simple linear extrapolation may be adequate. Because the Hodgson and Darnton best-fit model is non-linear, slightly different estimates are obtained by extrapolating linearly to intermediate values (such as the 0.02 fibres/ml.years) from the value above (0.1 fibre/ml.years) or value below (0.01 fibres/ml.years)

14.4 pOtenCy dIffeRenCeS Of ASbeStOS mIneRAlS

14 .4 .1 MesotheliomaWith respect to mesothelioma, crocidolite is more potent than amosite, which is generally regarded as much more potent than chrysotile. There is reasonable agreement between researchers regarding the potencies of amosite and crocidolite (HEI, 1991, Hodgson and Darnton 2000, and Smith and Saunders, 2007) but the relative potency of chrysotile remains contested.

If it is estimated that a child is exposed to airborne crocidolite while indoors for 23 hours per day, 365 days per year, for the first five years of life, that would amount to 23 × 365 × 5 ≈ 42 000 hours.

If the exposure concentration is 0.001 fibres/ml (ie 10 per cent of the clearance level) then the cumulative exposure would be 0.001 fibre/ml × 42 000 hours = 42 fibre/ml.hours. That is equivalent to 0.02 fibre/ml.years.

Mesothelioma risk: according to Table 14.1, the lifetime risk of mesothelioma for an adult exposed to 0.01 fibre/ml.years of crocidolite is ~20 per 100 000 exposed. So the risks at 0.02 fibre/ml.years will be roughly twice this value. However, this needs to be corrected for the increased risk resulting from exposure in childhood using the appropriate adjustment factor from Table 14.2. The factor for a child exposed from 0 to 5 years, assuming that risk persists for at least 80 years, is 6.6. This gives an estimated lifetime risk of mesothelioma of 2 × 20 × 6.6 ≈ 260 in 100 000 people exposed .

Lung cancer risk: according to Table 14.3, the lifetime risk of lung cancer from a cumulative exposure to 0.01 fibre/ml.years of crocidolite is ~2 per 100 000 exposed. So the risk at 0.02 fibre/ml.years will be ~4 per 100 000 people exposed . No age adjustment factor should be applied . Risks for smokers would be higher.

Excess lifetime cancer risk: is the sum of the mesothelioma and lung cancer risks (ie 260 + 4), which equals 264 per 100 000 people exposed.



Box 14.2 Mesothelioma

14 .4 .2 Lung cancerWith respect to lung cancer, there are widely varying estimates of the potency of chrysotile compared to amphibole asbestos. The clear implication is that it is necessary to be cautious about assuming that the chrysotile risks are as low as indicated in Tables 14.1 and 14.2.

Box 14.3 Lung cancer

14.5 unCeRtAInty In the mOdelSRisk assessors, and those reviewing or relying on the resulting reports, should be aware of the uncertainties from using the current models as these can have an impact on the evaluation under different legal contexts of the risk estimates.

The use of models from human epidemiology means that there is no uncertainty arising from interspecies differences. There is no extrapolation from small numbers (of animals in experimental studies) to very small risks in very large populations. The exposure risk models used for asbestos are based on epidemiological studies and/or meta-analyses of epidemiological studies. The studies are based on strong evidence from many thousands of exposed people and many hundreds of deaths from asbestos-related disease. The studies will have included sensitive individuals, but not children. There are reports of mesothelioma from exposure in infancy (eg Wagner, 1991). However there is extrapolation from the usually high levels of exposure down to the low doses relevant to exposure from asbestos in soil. So, the level of risk predicted from these models at the low doses of interest to environmental exposure depends to some extent (as previously highlighted) on the form of extrapolation adopted.

The risk predictions from Hodgson and Darnton are broadly consistent with results from the meta-analysis by Berman and Crump (2008). The linear risk prediction model from the HEI review (HEI, 1991) gives similar estimates to the Hodgson and Darnton best-fit model.

The HEI model (1991) indicates that the mesothelioma risks for amosite compared to chrysotile may be in the proportion 3.2:1 but the Hodgson and Darnton (2000) model suggests that the ratio may be 100:1. However, Hodgson and Darnton’s result for chrysotile greatly depends on the data from chrysotile miners, and there were apparent differences compared to other cohorts although those differences did not reach statistical significance (Hodgson and Darnton, 2010). A recent independent analysis by Berman and Crump (2008) suggested a similar ratio to that reported by Hodgson and Darnton (2000).

Loomis et al (2009) reported mesothelioma cases in a textile plant using only chrysotile. Hodgson and Darnton (2010) commented on this work and noted that, while still an order magnitude lower than those from amosite, the risk from chrysotile are much higher than those reported in their own earlier paper. Hodgson and Darnton (2010) concluded that the results of Loomis et al (2009) “certainly strengthen the case for the proposition that the ‘per fibre’ risk of mesothelioma from chrysotile in textile plants is greater than it is in the mines”.

Finkelstein and Meisenkothen (2010) and Burdorf and Heederik (2011) have also questioned the predicted risks of mesothelioma from chrysotile exposure. Also, Peto et al (2009) speculated that there may be an interaction in the development of mesothelioma where small amounts of amosite are inhaled with chrysotile.

Hodgson and Darnton (2000) estimated that the lung cancer risk for amosite exposure is 10 to 50 times that for a similar exposure to chrysotile. The HEI (1991) model indicates that the lung cancer risk from amosite is four times that of chrysotile, while Stayner et al, (1996) concluded that “it is prudent to treat chrysotile with virtually the same level of concern as the amphibole forms of asbestos”.

Berman and Crump (2008) found that there was a wide dispersion of estimated lung cancer potencies of chrysotile and amphiboles in different studies, with one of the highest potencies being found in a study of asbestos textile mill workers where the exposure was almost exclusively to chrysotile.

Burdorf and Heederik (2011) found that if papers that failed their quality criteria for exposure were excluded, the estimated risks of lung cancer from chrysotile exposure were between three and six times higher than if those papers had been included. They also noted that “for lung cancer, it cannot be excluded that the suggested differences in potency between chrysotile and other types of asbestos may be entirely due to quality issues since too many studies had major limitations in their exposure assessment”.

Hodgson and Darnton (2010) accepted that there appeared to be a real difference of about ten-fold in risk (relative to exposure) between chrysotile miners and cohorts of textile workers.


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In addition, Peto (1995) predicted, with remarkable accuracy, the dramatic increase in mesothelioma deaths many years before it peaked using risk modelling. There is substantial circumstantial evidence that extrapolation of the risk data to much lower exposures has validity as there have been many cases of mesothelioma where low level asbestos exposure is the most likely cause (Peto, 2009).

14 .5 .1 Exposures in epidemiological studiesThe accuracy of asbestos exposure estimated in epidemiological studies is a major source of uncertainty in current models.

Mesothelioma and/or lung cancer occur typically between 20 to 60 years after first exposure to asbestos. Due to this time lag, all the epidemiological studies relate to exposures that occurred in the 1930s, 1940s, 1950s, 1960s or 1970s. The exposure information in each study is based on various different types of measurement or evidence. In the later periods, there are measurements by phase contrast optical microscopy counts of fibres, but for some periods there are dust counts and sampling by other methods, and for some early periods measurements are absent. Therefore, some of the epidemiological evidence relies on estimations or assumptions, particularly regarding conversion of historical asbestos in air concentration into a form comparable with modern airborne fibre counts.

Tables 14.1 and 14.3 include the estimates of the uncertainty in the predictions, as stated by Hodgson and Darnton.

14.5.2 Applicabilitytonon-occupationalexposuresThe models of the exposure-risk relationships are based on occupational exposures generally at high concentrations for protracted periods. There is obvious uncertainty in extrapolating to much lower, non-occupational, environmental exposures, which may include exposure at a younger age. For example, the meta-analysis by Hodgson and Darnton (2000) estimated that the average cumulative exposures of the different cohorts ranged between 13 to 750 f/ml.year. As shown by the values in Tables 14.1 and 14.2, the models produced by such meta-analyses can be regarded as robust and valid for such occupational exposures. Inevitably the confidence in a model’s prediction reduces when it is used outside of the range of data from which it has been derived or calibrated (ie extrapolation), so the greater the extrapolation the lower the confidence (reflected in Tables 14.1 and 14.3).

Children are considered the ‘critical receptors’ in the assessment of land contamination for residential and allotment land uses (Jeffries and Martin, 2009). The UK Committee on Carcinogenicity (CoC) has recently considered the relative vulnerability of children to asbestos compared to adults (CoC, 2013). They identified two key considerations:

1 The effect of age at exposure and life expectancy.

2 A child’s intrinsic susceptibility to injury from asbestos.

Models for mesothelioma risk suggest that individuals exposed in childhood are at greater risk than those exposed later in life, because their longer life expectancy post exposure gives longer for the disease to manifest itself. The age adjustment factors in Table 14.2 for mesothelioma allow this to be accounted for in the assessment. In contrast, lung cancer models suggest there will be little or no increase in lung cancer risk whether exposure starts at age five or 50.

With respect to the intrinsic susceptibility of a child, CoC (2013) concluded that “From the available, albeit limited, data it is not possible to say whether children are intrinsically more susceptible to asbestos-related injury.” The current mesothelioma and lung cancer models are based on adult physiology and do not take account of the rapid growth rate and the different, and developing, physiology of children. So it is possible that childhood exposure to asbestos might result in greater mesothelioma and lung cancer risks than suggested by current models.



14 .5 .3 Extended exposure durationThe contribution to cumulative exposure matters when deciding if there a significant risk to health from asbestos in soil. So, risk assessments take into account both the duration and intensity of exposure. Concentrations of asbestos in air may vary with conditions and a single value for instantaneous concentration may be misleading.

Estimates of risks from current models are based on cumulative exposures over the course of a year (or for Hodgson and Darnton (2000) over five years). The risk estimated for 1 fibre/ml.years (or 2000 fibre/ml.hours) would be the same if the exposure occurred in one month or was spread over all 12 months. With the five year periods considered by Hodgson and Darnton (2000), this can be accommodated by calculating the equivalent cumulative exposure over five year periods. The risks from successive five year periods can be summed to give an overall risk (eg risk from exposure from age 0 to 20 could be accommodated by summing the risks from four successive five year periods with exposures starting at age 0, 5 10 and 15).

WATCH (2011) identified differences in exposure patterns as a limitation to the application of the Hodgson and Darnton (2000) model to non-occupational exposures. The occupational exposures that formed the basis of the current models were from exposure during the working day and over periods of up to a working life. This is likely to be different from many non-occupational and environmental exposure patterns. For example, a residential scenario could involve exposure from childhood through to old age (more than 70 years) and for at least 12 hours per day (potentially 24 hours per day during the initial years). Other scenarios, such as dog walking or sports activities, may involve exposure for a few hours every week over a lifetime.

Differences in the hours per day of exposure can be accommodated by calculating the cumulative exposure in fibre/ml.hours and then converting to fibre/ml.years by dividing by the number of working hours in a standard industrial working year (eg 48 weeks of 40 hours =1920 hours. Hodgson and Darnton assumed approximately 2000 hours).

The use of exposure-risk models is highly technical and taking the numerical output of such models at face value is too simplistic. Where such models are used with respect to ACSs it is important that all relevant uncertainties are clearly acknowledged within the report (especially about the accuracy of these models when applied to non-occupational asbestos exposures, particularly at low airborne concentrations) and the results interpreted with due caution. For example, commenting specifically on the application of the Hodgson and Darnton (2000) model to such situations, WATCH (2011) referred to the uncertainties mentioned earlier and stated that:

“WATCH considers that all of these uncertainties impose limitations on the reliability of risk estimates produced by the H&D model, particularly when it is extrapolated to exposure situations and populations beyond those covered by observed data. Hence WATCH confirms the statement in its 2008 conclusion that risk estimates derived by extrapolation of the model should not be taken to be reliable absolute risk values. The limitations on the reliability of risk estimates derived using the H&D model become more pronounced the further the model is extrapolated from the occupational exposure scenarios and data on which it is based.”

The uncertainty in the risk estimate, however, should be considered against the severity of the potential consequences of asbestos exposure given the legal context under which the assessment is being carried out. Despite the recognised uncertainties, the models remain an appropriate approach to estimating risks from exposure to asbestos (WHO, 2000, and WATCH, 2011). This implies that extrapolated risk estimates generated by the models might be most useful as rough indicators of the magnitude of risk

noteModels for past occupational levels of exposures can be extrapolated to environmental exposure levels where the level of risk is currently unknown. Extrapolation over many orders of magnitude means that resulting risk estimates can only be indicative and should not be used as absolute values. However, more research is needed in this area (see Chapter 18).


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that might be involved in different situations, and also the relative extent of concern and risk management action that can be justified under different legal contexts.

14.6 RISK evAluAtIOnThe numeric risk estimates produced by exposure-risk models need to be evaluated to determine their significance under specific legal contexts. The models generate risk estimates that can be expressed either as absolute risks (ie a probability of excess lifetime cancer, such as 0.0002) or as risks per population size (eg 20 cancers per 100 000). As each model produces a separate risk estimate for mesothelioma and lung cancer, these are summed to indicate the overall excess lifetime cancer risk (ELCR).

Determining the significance of the estimated ELCR, will also require site-specific consideration by the risk assessor as the level of risk deemed acceptable (eg under planning) or unacceptable (eg under the Environmental Protection Act 1990) will vary.

Risk evaluation in the UK is complicated by the lack of authoritative guidance on what ELCR may be considered ‘acceptable’ or ‘unacceptable’ as regards to exposures to environmental contaminants. Practitioners often rely on extrapolating guidance produced by the HSE with reference to occupational risks (eg HSE, 2001). However, there are additional considerations regarding exposure to environmental contaminants, such as the lack of control or consent regarding such exposures of the public.

The HSE (2001) generally consider occupational risks within three categories:

�� unacceptable

�� tolerable

�� broadly acceptable.

However, it is acknowledged that the concept of ‘acceptable’ risks relates to societal perception and that the classification of risk is complex and dynamic as the public perception of risk can change over time. For occupational activities, the HSE (2001) suggest that “an individual risk of death of one in a million per annum for both workers and the public corresponds to a very low level of risk and should be used as a guideline for the boundary between the broadly acceptable and tolerable regions”. Assuming a 70 year lifetime, this equates to risk of death of seven in a 100 000 over a lifetime.

UK guidance on toxicological assessment of soil contaminants (Hosford, 2009) suggests that where suitable human cancer data is available, and while acknowledging the imprecision of quantitative estimates of cancer risk, an ELCR of 1 in a 100 000 would represent ‘a minimal excess risk of cancer’. Similarly, WHO (2011) use an ELCR of 1 in a 100 000 as the basis for setting guideline values for genotoxic carcinogens in drinking water. Consequently, ELCR below this level are often considered to be ‘acceptable’.

It is important for landowners and developers to realise that the levels of risk that may be relevant to determining the condition of land in Part 2A or redevelopment scenarios may not be the same as the levels of risk considered important for decisions in civil litigation. As described and discussed earlier (see Chapter 3), the Supreme Court ruling in Sienkiewicz v Greif concluded that a four in a million (or 0.4 in 100 000) increase in the lifetime risk of mesothelioma amounted to a material contribution to the risk of the Claimant developing her mesothelioma (UKSC, 2011). So, it is possible that ‘negligent’ landowners responsible for ACSs may be liable to future compensation claims arising from alleged exposure at such levels of risk even if such levels would put land into Category 3 or 4 and outside the definition of statutory contaminated land.

note‘Tolerable’ in this context refers to “a willingness by society as a whole to live with a risk so as to secure certain benefits in the confidence that the risk is one that is worth taking and that it is being properly controlled. However, it does not imply that the risk will be acceptable to everyone, ie that everyone would agree without reservation to take the risk or have it imposed on them” (HSE, 2001).



It is also important to consider that ACSs are currently one of the few sources of asbestos exposure that are not directly regulated. So, consideration should be given as to whether landowners may face additional liabilities in the future if regulation over ACSs becomes more stringent. For example, the occupational exposure limit for asbestos has fallen by a factor of about 300 since 1960. The incidence of asbestos-related disease is still rising in the UK (mainly due to historical industrial exposures) and there is growing concern about more recent exposures from asbestos materials in buildings, such as schools built in the 1960s and 1970s. It is conceivable that such concerns may extend to environmental exposures in the future.

14 .6 .1 Unacceptable levels with respect to Part 2AThe Part 2A Statutory Guidance for England (Defra, 2012a) and Wales (Welsh Government, 2012) sets out general principles for determining risks that would lead to the determination of land as contaminated under the Environment Protection Act 1990, Part 2A, in England and Wales (see Table 14.4). The guidance adopts a narrative rather than numerical description of different levels of risk. Defra (2012a) emphasise that local authorities keep in mind the overall objectives of Part 2A in making any determination.

The changes to the statutory guidance made by Defra and the Welsh Government in 2012 have added detail to those circumstances that constitute ‘significant possibility of significant harm’. Since the guidance does not specifically discuss asbestos, an attempt has been made to map the definitions of Ccategories 1 to 4 on to asbestos-related evidence (see Table 14.4).

Different guidance is in force in Scotland, which refers to an undefined ‘unacceptable intake’.

Table 14.4 Categories of land with respect to ‘significant possibility of significant harm’ to human health (England and Wales only). For definitive descriptions of the categories, see Defra (2012a) or Welsh Government (2012)

Category description potential interpretation for asbestos in soil

1

(a) Similar land or situations are known, or are strongly suspected on the basis of robust evidence, to have caused such harm before in the United Kingdom or elsewhere; or

(b) Similar degrees of exposure (via any medium) to the contaminant(s) in question are known, or strongly suspected on the basis of robust evidence, to have caused such harm before in the United Kingdom or elsewhere;

(c) Significant harm may already have been caused by contaminants in, on or under the land, and that there is an unacceptable risk that it might continue or occur again if no action is taken. Among other things, the authority may decide to determine the land on these grounds if it considers that it is likely that significant harm is being caused, but it considers either: (i) that there is insufficient evidence to be sure

of meeting the “balance of probability” test for demonstrating that significant harm is being caused; or

(ii) that the time needed to demonstrate such a level of probability would cause unreasonable delay, cost, or disruption and stress to affected people particularly in cases involving residential properties.

Comparison against similar circumstances.


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2

There is a strong case for considering that the risks from the land are of sufficient concern that the land poses a significant possibility of significant harm. Category 2 may include land where there is little or no direct evidence that similar land, situations or levels of exposure have caused harm before, but nonetheless the authority considers on the basis of the available evidence, including expert opinion, that there is a strong case for taking action under Part 2A on a precautionary basis.

Asbestos contamination is present in soil to an extent and in a condition that the potential exposure to airborne asbestos for humans is likely to give rise to significant probability of disease.Direct measurements or robustly modelled estimates of airborne fibre concentrations from the significant contaminant linkage are at levels comparable with those associated with adverse health effects in the literature, particularly in documents from authoritative organisations such as HPA, HSE, WHO, ATSDR.

3

The strong case described [above] does not exist, and therefore the legal test for significant possibility of significant harm is not met. Category 3 may include land where the risks are not low, but nonetheless the authority considers that regulatory intervention under Part 2A is not warranted.

Airborne asbestos levels above potential background concentrations (eg >0.0001 f/ml) (see Section 6.3).Land that is not causing exposure above the clearance indicator threshold’ but that cannot be placed into Category 4.Needs to be read alongside the judgements in the Sienkiewicz (UKSC, 2011) and Williams (BAILII, 2011) cases.

4

(a) Land where no relevant contaminant linkage has been established.

b) Land where there are only normal levels of contaminants in soil.

(c) Land that has been excluded from the need for further inspection and assessment because contaminant levels do not exceed relevant generic assessment criteria.

(d) Land where estimated levels of exposure to contaminants in soil are likely to form only a small proportion of what a receptor might be exposed to anyway through other sources of environmental exposure (eg in relation to average estimated national levels of exposure to substances commonly found in the environment, to which receptors are likely to be exposed in the normal course of their lives).

CSM shows no source or no pathway or no receptor.Airborne asbestos levels below potential background concentrations (ie <0.0001 f/ml) (see Section 6.3).Estimated cumulative exposure to airborne asbestos is sufficiently low for risks to be deemed insignificant (from Tables 14.1 and 14.3).Johnson et al (2012) were not able to define normal background concentrations (NBC) for asbestos in soil.There are no relevant GAC for asbestos at the time of writing.Direct measurement difficult in many circumstances as weather is an issue.

Under Part 2A, the considerable variation in land use possible within an existing planning consent needs to be considered. For example, a domestic garden currently paved, may in future be cultivated by either an existing or future resident without requiring new planning approval. The temporary nature of the paving and its protective effect would need to be considered in any detailed assessment of the property under Part 2A.

14 .6 .2 Acceptable levels with respect to redevelopmentHuman health risk assessments made by or on behalf of the developer or owner for the purpose of planning need to demonstrate the process of “securing a safe development” (DCLG, 2012, and Welsh Government, 2012). In practice this is achieved through a [soil] risk assessment of the land contamination. While the technical details for assessing the risks from asbestos in soil differ from other contaminants, the general principles still apply.

Table 14.4 Categories of land with respect to ‘significant possibility of significant harm’ to human health (England and Wales only). For definitive descriptions of the categories, see Defra 2012a or Welsh Government, 2012 (contd)



Summary

�� there are currently no suitable generic assessment criteria for assessing risks from asbestos in soil in the UK. In particular, the hazardous waste threshold(seeSection3.6)andthevalueof0.001percentmentionedinICRCL(1990)shouldnotbeused

�� due to the limited current understanding of the soil-to-air fibre release relationship for asbestos, it is inappropriate to attempt to calculate any such generic assessment criteria for soil at present, unless supported by new UK policy decisions

�� the most scientifically-valid approach to assessing the risks from ACS is to estimate potential cumulative exposures to airborne fibres and calculate the associated risks using exposure-risk models

�� potential exposures can be estimated based on air monitoring data or predicted from soil concentrations using empirical relationships or measure the fibre release potential of soils samples. There are significant strengths and weaknesses in all approaches. The use of multiple lines of evidence is recommended

�� exposure-risk models are available for asbestos that will predict the lung cancer and mesothelioma risks associated with exposure to airborne asbestos. A simple procedure for employing the model described by Hodgson and Darnton (2000) to assess exposures from soils has been presented

�� these models are robust for past occupational levels of exposures and they can be extrapolated to environmental exposure levels

�� the actual risks from low exposures to asbestos are currently unknown. Extrapolation over many orders of magnitude means that resulting risk estimates are indicative rather than absolute

�� decisions or recommendations regarding the acceptability or unacceptability of the estimated risks produced should take full account of the uncertainties involved

�� any reports should fully describe and justify the assessment process used and the uncertainties, with reference to the specific legal context.


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15 Remediation and risk management

15.1 RemedIAtIOnIf the risk evaluation concludes the site poses, for example, a significant possibility of significant harm (Part 2A) or is not demonstrably safe (DCLG, 2012) then remedial action is needed. Currently, the default action at many sites is to remove any ACSs that are present or encountered during remediation. This can be costly, unnecessary and indeed may increase the risks to workers and the public.

A wide range of alternative remedial technologies and techniques are currently available in the UK. However, the application of many of these to ACSs is limited by the very properties that made asbestos such a widely used material in the first place. Asbestos does not burn or vaporise, it is biologically inert and persistent, and it is chemically unreactive. So, the application of most biological, thermal and chemical remediation methods to ACSs will not be successful. Some other remedial approaches also have significant drawbacks in the case of asbestos, such as ongoing liabilities, property blight and potential health and safety concerns.

At each site the selection of an appropriate risk management option(s) will be influenced by a wide-range of factors including:

�� type and levels of asbestos present

�� area or volume of soil

�� timescale and budget

�� other contamination at the site

�� current or proposed land use

�� community support or opposition.

It is also particularly important to consider the occupational health and safety implications of any management or remedial solution.

Another key consideration will be the attitude and stance of the relevant regulators, including the relevant local authority, HSE and environmental regulator (eg Environment Agency in England and Wales, SEPA in Scotland, and NIEA in Northern Ireland). There can even be variation within the different agencies, regional offices or even between different individuals in such organisations. So, early and continued consultation and discussion with the relevant regulators is essential.

Several of the techniques described here are applicable to a wide-range of contaminants in addition to asbestos (eg cover systems and capping, off-site disposal, soil washing and solidification). When developing a remedial strategy, the potential cost-savings available by employing a single such technique to treat asbestos and other contaminants should be explored. Implementing a separate asbestos-specific solutions may not be the optimal approach at some sites.

Guidance on the selection of appropriate remedial options and the development of a remedial strategy is presented in CLR11 (Environment Agency, 2004). However, it is important to remember that the aim

AimThis chapter summarises current and emerging approaches to the management and remediation of ACSs, highlighting relevant considerations when leaving them in situ or capping, treating or disposing of them to landfill. The verification requirements are summarised as are requirements for documenting where ACSs are present post remediation. The availability of additional liability transfer solutions for any residual risks is noted. In any event, any remediation involving ACS must comply with CAR 2012.



of any risk management actions is to ensure that all risks (real or perceived) are reduced to minimal or acceptable levels and that this requires appropriate risk management measures, not necessarily remedial intervention. It is important to have an ‘open mind’ during any options appraisal process to ensure that all feasible options are considered in order to derive an optimal and cost-efficient solution.

The critical importance of complying with CAR and other health and safety considerations when working with ACSs (including the need for a suitable CAR risk assessment and appropriate training) is discussed in Chapter 8.

15.2 leAve iN situThe presence of ACSs does not necessarily require them to be removed or treated. Where the soil risk assessment has shown that ACSs pose negligible risks, it may be appropriate to leave them in situ and undisturbed without further control measures. This is likely to apply particularly to asbestos in made ground at depth (eg deeper than 1.5mbgl).

Even when an initial soil risk assessment indicates unacceptable risks, leaving the materials in situ but applying various receptor modification strategies (see Box 15.1) should be assessed to see if these would provide adequate risk management. Such strategies may prove significantly more cost effective than classic remediation options. Suitable strategies are available that may, in some circumstances, meet the requirements under either Part 2A or redevelopment contexts.

The principal advantage of leaving ACS in situ is that it minimises potential exposure to workers or the public during remedial works. It also entails little or no disposal costs.

Where ACSs are to be left in situ, measures will be needed to ensure that other works during the remediation and/or redevelopment of the site do not increase the risks, for example by exposing buried asbestos at the surface. Adequate documentation will be needed to ensure that subsequent owners/occupiers are aware of the location of the ACS and the nature and limitations of the control measures (see Section 15.7).

Due to the real and perceived risks associated with asbestos, leaving ACSs in situ may have limited applicability to sensitive land uses (eg residential developments) or at sites where future disturbance may occur (eg agricultural land, allotments, gardens) (ICRCL, 1990). A ‘do nothing’ approach may meet with opposition from some enforcement authorities or the wider community. Where that is the optimal solution, it may be more appropriate to invest in informing site occupants and neighbours why this is the preferred option, rather than adopt alternative methods or additional sampling and analysis, which may not add value to the process (enHealth, 2005).

Box 15.1 Receptor modification strategies applicable to asbestos-contaminated soils

Receptor modification strategies applicable to ACSs include:

�� change the layout or design of the site (eg placing buildings, roads, pavements, car parks, paving or other hard landscaping over the affected areas of the site)

�� change proposed land use (from residential) to one that is less sensitive with respect to asbestos (less sensitive land uses may include, for example, industrial, commercial, car parks)

�� implement site security measures to prevent exposure to the public or trespassers�� implement asbestos mitigation measures to minimise exposures for site workers.

Such approaches may be advantageous where:

�� the ACSs are already buried at reasonable depth�� the distribution of ACSs is complex or difficult to determine�� ACSs cover a large area�� the site does, or will, include large areas of hardstanding�� redevelopment of the site will already require capping the site with clean fill (ie for geotechnical or other purposes).

If necessary, these options can be used in conjunction with other techniques that address the ACS source, such as caps, barriers, excavation or treatments, to result in a cost-effective risk management approach for the site as a whole.


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15 .2 .1 Cover systems and cappingIf the soil risk assessment shows that leaving the affected soils in situ will pose potentially unacceptable risks, then more proactive intervention is required. It may still be possible to leave the materials in situ if additional surface cover, or a cap, is provided across the affected area. It may also be appropriate to reduce the risks by treating the soils using an in situ technique, such as hand-picking or solidification. The presence of asbestos below the surface cover or cap would need to be adequately documented (see Section 15.7).

Such caps may be made of soil, sand, aggregate, rubble or clay etc. Any cap should also be designed to withstand the anticipated erosion due to physical wear, water runoff and wind etc. It is also common to include break or marker layers at the base of the capping layer to indicate the presence of asbestos in the ground below. Such layers are commonly geotextiles, which should be water permeable, rot-proof and chemically resistant and have high tensile strength. They should be applied across the total surface of the ACSs (preferably extend beyond the boundary) and parallel layers should be suitably secured together or overlapped by at least 20 cm.

The required depth of cover or capping is a contentious issue in the UK, as there is no statutory minimum depth. The guidance provided by Tedd et al (2004) relies on dilution of chemical contamination. This guidance should not be applied to ACSs, as it will not ensure that asbestos fibres are not exposed at the soil surface. In general, the depth should be based on factors that include the type, amount, concentration and condition of the asbestos, the current or future land use and the client’s or landowner’s position on residual risks. However, the overriding factor will be demonstrating that inadvertent disturbance of the ACS is sufficiently unlikely. The depth of any cap for ACSs requires regulatory approval from the local authority and, potentially, other regulators.

In cases of significant levels of asbestos at privately-owned housing, a depth of 0.6 m to 1 m of cover may be required to provide adequate protection, given that some gardeners may double dig to 0.6 m, and the installation of a pond may require excavation to at least 0.9 m. Even this may not be sufficient in some instances. The use of a geotextile barrier may make a lesser depth sufficient where this is justified by the risk assessment. Shallower depths may also be appropriate in non-domestic situations (eg commercial and industrial developments, civic buildings, prisons, schools) where an appropriate asbestos management plan (see Section 15.7) can be enforced to provide additional levels of protection.

In some very low-risk situations, well-established and properly maintained vegetation may provide an appropriate level of protection on its own or may be used to provide additional protection to a soil capping layer from subsequent erosion (enHealth, 2005, and ICRCL, 1990). However, arrangement for regular inspection and ongoing maintenance of such a vegetative barrier would be needed to ensure the robustness of the solutions.

note

The cap consisted of a break layer of 1000 gauge geotextile protected with 300 mm of imported aggregate (Type 1), topped with 1.0 m of formation materials. Any visible asbestos was hand-picked from the surface before the geo-textile was put down. The area was surveyed so that it could be re-located accurately and details entered into the health and safety file.

Figure 15.1 Construction of a cap over a deep pocket of asbestos-containing soil (courtesy Hydrock)



15.3 On-SIte ReuSe OR tReAtmentWhere ACSs cannot remain in situ and will be excavated, it may be appropriate to reuse, treat or dispose of the arisings. According to the waste hierarchy, the disposal of ACSs should be a last resort and such soils should be reused (treated or untreated) wherever possible. However, in some situations disposal may be the only practicable remedial option.

Further advice on the reuse of soils may be found in the current version of CL:AIRE (2011).

The exposure of site workers during any excavation, storage, treatment, placement or disposal of such ACSs should be assessed and managed in accordance with the requirements of CAR. Consideration should be given to the fact that excavation in itself may be sufficient to break and disperse very friable materials. The damping down of soils before and during excavation etc (Figure 15.2) can significantly reduce the release of airborne fibres. However, additional controls, such as cleaning and wetting roadways, managing stockpiles, wheel washes, vehicle washes, PPE, RPE, hygiene facilities and sealed vehicle cabs with filtered air supplies, may need to be considered.

Figure 15.2 Damping down and use atomised water sprays to inhibit the release of airborne asbestos fibres during a skip being loaded (a), and soil stockpiling (b) (courtesy Hydrock)

15.3.1 On-sitereuseofasbestos-containingsoilsACSs are commonly reused at sites in the UK, particularly those containing ‘trace’ amounts of asbestos and as fill materials to be placed at depth. Any such reuse of ACSs needs to be adequately documented (see Section 15.7).

The reuse of such soils needs to be supported by a valid soil risk assessment and any movement of ACSs conducted in-line with CAR and current waste legislation. In any case, on-site reuse of ACSs needs to be carried out with care if future legal liabilities are to be minimised and early consultation with the relevant regulators is also recommended.

Many of the considerations applicable to leaving soils in situ and the use of cover and capping systems (Section 15.2) are also relevant to the on-site reuse of ACSs. This includes a consideration of:

�� the depth at which such materials are to be placed

�� any relevant institutional controls

�� the location of the materials relative to the site design and layout.

15.3.2 On-sitedisposalHistorically, in the UK and elsewhere, the possibility of on-site disposal of ACSs has been suggested (Western Australia, 2009a and ICRCL, 1990). This has historically been described as “burial at depth” and differs from reuse (see Section 15.3.1) in that the primary objective is the disposal of such materials.

a b


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Under current legislation such approaches would generally be regarded as waste disposal activities and be subject to all legislation relevant to the operation of a landfill. Consequently, such an approach will require significant legal and regulatory liaison as such a facility will require separate planning permission and an environmental permit.

Despite the effort needed to obtain the relevant approvals, this option may be applicable at a limited number of UK sites where sufficient space is available for the construction of an appropriate landfill cell and where the reduced costs compared with traditional off-site disposal make it cost effective. Such an approach may also be advantageous at heavily contaminated sites where off-site transportation of ACSs may result in the spread of asbestos off-site and exposure of the general public, or would be politically unacceptable.

15.3.3 On-sitetreatmentofasbestos-containingsoilsWhere the soil risk assessment demonstrates that the ACSs are not suitable for reuse on-site, a number of on-site treatment techniques are available. Such treatment may require authorisation from the relevant regulatory authorities. The treated materials may then be suitable for reuse on-site, but such techniques have also been used to pre-treat soils before disposal. Pre-treatment may be necessary for waste soils destined for landfill but may also reduce disposal costs, for example if treatment can reduce hazardous waste soils to a non-hazardous waste, or if a significant volume reduction is achieved. Such treated materials should not be reused off-site, unless the recipient is aware of the source and nature of the potential contamination and adequate regulatory approval has been obtained.

Most treatment techniques, seek to separate fragments of asbestos from the soils. The asbestos removed by such methods is usually then disposed of as asbestos. Friable ACM will be more difficult to remove from the soil and is likely to involve removal of associated soil to ensure any fibres are also removed. Advice should be sought from specialists before any form of asbestos waste is removed from site. If necessary, consult the HSE regarding appropriate packaging and transport arrangements.

For quality control and verification purposes, sampling and analysis of the treated soils is usually required to ensure removal efficiencies are maintained and that site-specific remedial objectives are met. This is particularly true if the treated soils are to be left exposed at the soil surface. Such analysis should include microscopy methods capable of detecting free fibres, which may be liberated from ACM during excavation and processing activities.

Treatment of ACSs will inevitably increase the potential exposure of workers to asbestos. Also, other health and safety issues, and the costs involved, should be a significant consideration during the options appraisal process. Compliance with CAR 2012 will require suitable and sufficient health and safety risk assessments for all the activities involved and appropriate control measures, where necessary, and monitoring the release of airborne fibres. As a minimum this will involve damping down procedures and air monitoring to ensure the protection of workers and the public, but may include enclosure of the treatment process within temporary structures (such as tented areas), which may be under continuous negative pressure. The remediation will need to comply with CAR 2012 (see Section 8.1.3).

If excavated soils are to be stockpiled before treatment, controls will also be needed to ensure that they do not give rise to airborne fibres. This may involve covering the stockpiles, damping down procedures or the use of temporary enclosures. Similar precautions should be applied to any stockpiles of treated soils, particularly until the residual levels of asbestos have been quantified.

15.3.4 Hand-pickingofvisibleasbestosfromsoilorrubbleHand-picking is the manual removal of visible asbestos from soil or rubble. It is suited to the removal of asbestos cement and other non-friable materials. Hand-picking of friable materials is less effective and more dangerous, and the health and safety precautions mean that it is likely to be more costly. It is not applicable to the treatment of free-fibres. All hand-picking must comply with CAR 2012.



Hand-picking has been widely used at UK sites, with treatment having been implemented with the soils in situ or ex situ following excavation, often in temporary enclosures.

In situ methods usually involve one or more trained operatives, supported by appropriate health and safety support and supervision, systematically searching and examining the surface of the affected area. Manual disturbance using spades, hoes or rakes etc may also be involved to remove visible asbestos from soils just below the surface. Raking, hoeing, digging and mechanical tilling are all dusty activities. The CAR risk assessment should help identify appropriate control measures to minimise workers’ exposures. Mechanical tilling may also be used. Depending on the removal efficiency required to meet the site-specific remedial objectives, hand-picking may be quick and target only reasonably sized pieces of ACM or it may be slow removing all visual ACM. Multiple passes across the area may be required. In the UK this is sometimes referred to as ‘potato picking’ and in Australia as the ‘emu-bob’, presumably due to the actions involved in picking up fragments of asbestos. Alternatively, for buried asbestos, hand-picking can be integrated with careful mechanical excavation with the excavation arisings or face of the excavation being picked over.

However, at many sites more robust occupational control measures have required enclosed ex situ hand-picking. Suspected ACS is excavated and transferred to a designated treatment area. The treatment area is usually laid out to assist operatives find, identify and remove ACM. For example, the excavated soil may travel past the operatives on conveyor belts while being misted with water and special hoppers may be located at each work station to collect the removed ACMs.

Figure 15.3 Handpicking of asbestos and ACMs from stockpiled soil (courtesy VSD Avenue, a consortium comprising VolkerStevin Ltd, Sita Remediation NV and DEME Environmental Contractors BV)

15 .3 .5 ScreeningScreening usually refers to the ex situ removal of asbestos cement fragments by mechanical screens, trommels and or sieving methods. Soils would generally be excavated and stockpiled for treatment at a designated treatment area. The minimum size of the fragments removed is defined by the specification of the equipment used, particularly by the mesh size employed. However, the shape and nature of the ACMs involved are also important. For example, while fragments of asbestos cement can be removed efficiently, asbestos rope has proved more problematic due to its flexibility.

Due to the mechanical action of these treatments airborne asbestos fibre may be generated, so such methods are most applicable to firmly bound materials (eg asbestos cement) that can withstand processing. They would not generally be appropriate for soils containing friable materials (including degraded asbestos cement). CAR 2012 requires appropriate control measures to control any dust generated during screening of ACSs.

Screening works most effectively for loose, granular or sandy soils, so compacted soils or soils with high clay content may also not be suitable for treatment. The oversize materials removed by screening will include large fragments of ACM but also rubble, boulders, scrap metal etc. As a result, large volumes of


CIRIA, C733134

waste may be generated where soils contain significant amounts of demolition rubble etc. The resulting disposal costs may make this option uneconomical.

15.3.6 SolidificationSolidification/stabilisation (Box 16.2) is now an accepted treatment for a wide range of contaminants in the UK, but elsewhere it is also routinely applied to ACSs.

In situ treatment would involve mixing appropriate binders into near surface ACSs using harrows or rotavator-type equipment, or using augers or other devices to treat deeper soils.

In a typical ex situ treatment, the affected soil is excavated, moved to a designated treatment area and them mixed with the binder using appropriate plant and equipment. The mixed materials would normally be replaced in a suitable location at the site. Once solidified the treated materials are likely to have considerable load bearing strength, so such materials are frequently used as sub-base for pavements, roads, buildings or car parking.

Box 15.2 Outline of the application of solidification/stabilisation to asbestos-containing soils

15.3.7 Off-sitedisposalDisposal of ACSs at an appropriate off-site landfill offers a number of advantages in terms of reliability, predictability, certainty and minimal residual risk to future land. Indeed, in some situations off-site disposal may be the only practicable remedial option.

Off-site disposal is subject to current waste legislation, including the legal duty of care. Before removing any ACSs from site, advice should be sort from specialists and the relevant regulator (ie HSE and Environment Agency) regarding appropriate packaging and transport arrangements.

ACSs may be classed as hazardous waste and the resulting costs (including pre-treatment and transport costs) can be substantial, particularly if large volumes of soils are involved. In such cases, on-site treatment (see Section 15.3.3) may reduce the costs by significantly reducing the volume of material requiring disposal or its waste classification.

15.3.8 Off-sitetreatmentTo date there are no known soil treatment centres, or CLUSTER projects (CL:AIRE 2012), specifically aimed at ACSs. However, off-site application of some or all of the on-site treatment technologies described here may be practical, particularly solidification. Such soil treatment may become available in the future. It is also possible that some of the future or emerging technologies described in the following section may become established for the off-site treatment of ACSs particularly if low cost and zero carbon sources of electricity are available.

15.4 futuRe And emeRGInG teChnOlOGIeSThe known hazard and lack of appropriate disposal options for asbestos materials, has led to several potential innovations being brought to market. Although these are primarily aimed at disposing of undiluted asbestos wastes, they may be relevant to soil treatment at some sites. They may also be appropriate for the disposal of asbestos removed from soils by hand-picking, screening etc.

Solidification/stabilisation techniques use a variety of binder substances to impart physical/dimensional stability and to contain the asbestos in a solid product (or monolith). This is normally achieved using cement or lime based binders although a variety of secondary additives may also be added (eg pulverised fuel ash or ground granulated blast furnace slag). An appropriate blend of such additives will produce a dense solid concrete-like material from the original soil, within which any asbestos materials will be trapped and sealed. However, a variety of other binders have also been used for solidification including thermoplastic resins, polymer cement and asphalts and bitumens, which may all be used with or without secondary additives. Once encapsulated in such a matrix any asbestos is unable to escape into the air or surrounding soil.



15 .4 .1 Soil washingSoil washing removes contaminants by exploiting differences in solubility, particle size and density and is now regularly used on granular soils in the UK. Compared with screening methods, the release of airborne fibres is likely to be minimal due to the water added during soil washing. However, where the waste arisings (including waste water) contain asbestos they will require appropriate treatment or disposal.

There are reports of soil washing being applied to ACSs in the UK, but in these cases asbestos appears to have been a minor contaminant. Soil washing will be difficult to apply to free fibres in soil and may not be easy if the soil contains diverse ACMs with various different densities.

15 .4 .2 In situvitrificationIn situ vitrification involves solidifying contaminated soils by the melting of the silica component (ie sand or glass cullet added to soils) to form a very low permeability and durable obsidian-like material. The heat required is usually supplied by applying very high voltages to electrodes sunk into the soil. Although asbestos does not burn, it will melt at the temperatures needed for vitrification, and so permanently destroying asbestos fibres. Although it is costly, its ability to simultaneously treat a wide range of other contaminants with very high efficiencies means that it may be a cost-effective solution at some sites. In situ vitrification is commercially available worldwide, but to date it is not believed to have been applied at sites in the UK. Vitrification may be viable for ACMs containing a significant percentage of asbestos (eg greater than 10 per cent, but will be less viable for soils with low asbestos content where a very high proportion of the energy will be expended on the non-asbestos content. (This is also relevant to techniques in the following sections –plasma arc, thermo-chemical conversion, and microwave destruction).

15 .4 .3 Plasma arc technologyTetronics and Europlasm (see Useful websites) are currently commercialising plasma arc technology to destroy asbestos and produce an inert slag material that can be reused as aggregate or in construction products etc. As for vitrification, it should also be able to treat other contaminants and so could potentially offers a single cost-effective solution in specific cases. Although the treatment of contaminated soils has been discussed, it is now known if any UK projects involving ACSs have been successful.

15.4.4 Thermo-chemicalconversiontechnologyThermo-chemical conversion is a patented process for the treatment of asbestos wastes from ARI Technologies Inc. (see Useful websites). It uses chemical fluxing agents to minimise the temperature at which asbestos remineralises, which allows asbestos to be destroyed at lower temperatures than other technologies (European Commission, 2006). It is understood that ACSs have been treated using a 20 ton/day demonstration plant and is being considered for full-scale implementation at several sites in the US (ARI Technologies pers comm). The commercial viability of the technology for the treatment of asbestos wastes (including soils) in the UK is currently being assessed (ARI Technologies pers comm).

15 .4 .5 Acid destructionDigestion material for asbestos (DMA) technology was developed in the late 1990s and has subsequently been licensed to a number of US suppliers (see Useful websites). It uses a phosphoric acid-based foam to treat chrysotile (in porous materials such as sprayed fireproofing) while still in place within buildings. In contact with chrysotile asbestos it initiates chemical digestion of the fibres, dissolving them and forming apparently harmless mineral fibres, which retains the function of the asbestos in the material but is no longer regulated as such. It is not effective in treating amphibole asbestos types. It is not known if this technology has been evaluated for use on ACSs but it may have some applicability as an in situ treatment although the use of large quantities of phosphoric acid in situ may raise other environmental contamination issues.


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15 .4 .6 Microwave destructionThere is currently considerable research regarding the use of advanced microwave technology in the destruction of asbestos wastes with the aim of producing an inert vitrified waste. Research in this area has been published by Università di Modena e Reggio Emilia, Italy, and the company ATON-HT S.A, Poland (see Useful websites). The technology appears to still be in development and it is not clear if it has been deployed commercially for ACSs.

15.5 veRIfICAtIOnExtensive guidance has been published on the verification of land remediation (Environment Agency, 2004 and 2010). Some issues and considerations particularly relevant to asbestos remediation projects are highlighted as follows. Verification reports should also meet any requirements stated by regulators, including the local authority.

The current guidance highlights the need for robust verification using multiple lines of evidence (See Box 16.3) to demonstrate site-specific remediation objectives have been met. These objectives are likely to be site-specific thresholds for soil concentrations (or potentially air concentrations) or the characteristics of containment solutions (eg minimal depths and construction of cover systems, density and design life of solidified materials). In any case the objectives should be based on a scientifically robust site-specific soil risk assessment and agreed with the relevant regulators.

Box 15.3 Application of ‘lines of evidence’ approach to asbestos-containing soils

As well as setting such remediation objectives, the nature, quality and quantity of evidence that will be provided to demonstrate compliance with the objectives should also be agreed. This may, for example, include the number of soil or air samples that will be collected, a description of the sampling and analytical procedures (eg LoD) that will be used to analyse them and a description of how compliance will be assessed. Agreeing such factors beforehand with relevant regulators and stakeholders may go a long way in pre-empting later disagreements and health scares.

Visual screening should not be relied upon to demonstrate that soils are suitable for reuse, or asbestos fibres are not present, without laboratory confirmation.

The use of mobile facilities can help rapid provision of results to aid decision making. The asbestos industry routinely uses on-site (optical) microscopy laboratories to allow rapid analysis of air samples. However, any air samples requiring analysis by electron microscopy will need to be sent to an offsite laboratory. Mobile laboratories can also be used for qualitative analysis of soil samples etc but are less common. In principle, an on-site laboratory could also be set up for quantitative analysis of soil samples

Many of the lines of evidence applied to chemical contaminants (such as geochemical and biodegradation indicators, stable isotope analysis) are not relevant to asbestos, which is non-biodegradable and chemically stable. However, a ‘lines of evidence’ approach should still be employed. For example, where picking or sorting approaches have been used to remove ACM and achieve a specified reduction in asbestos in soil levels, primary evidence of compliance is likely to relate to laboratory soil asbestos tests, but this could be supported by, for example

�� photographic evidence of the picking/sorting activities�� photographs of soils pre and post treatment�� detailed records of the origins and destination of the treated soils�� data on the mass and types of ACM removed�� waste transfer records for the disposal of these materials.

None of these data alone would provide robust verification, but collectively they provide strong supporting evidence that the remedial objective has been achieved.

In the case of containment solutions (capping or stabilisation), there may be less scope for multiple lines of evidence. So, uncertainty in the primary evidence on the effectiveness of the containment (depth of cover, or integrity of solidified materials etc) may need to be addressed through the data density (ie the number of test locations), applying safety margins to the remedial design (ie increased depth of cover) and/or by incorporating additional layers of protection (eg geotextile break layers with asbestos warning information).



but costs would be high and suitable accommodation is not available at most sites. However, quantitative analysis of soil samples is more complex and time consuming, so the transport time is not usually the rate controlling step. As a result, most soil samples are sent to an off-site laboratory for quantitative analysis.

Where any qualitative or quantitative analysis of soils is performed on site, some confirmatory samples may still need to be sent for off-site analysis.

It is important that any testing performed on soil samples complies with specification in the verification plan – and this specification may differ significantly from that normally conducted in the laboratory. For example, lower limits of detection and quantification and specific details of the numbers of free fibres may be needed (see Chapter 11).

Due to the risk perception issues surrounding asbestos, it is particularly important that once a verification plan has been agreed with the regulators, the required data is collected diligently so that a scientifically-valid verification report can be prepared. Finally, consideration should be given to how the verification should be communicated to stakeholders (see Chapter 17). This is likely to be critically important in maintaining public confidence in the remedial process.

15.6 ImpORtInG SOIlS And AGGReGAteSIt is relatively common to encounter between 0.01 to <0.001 per cent asbestos in modern recycled aggregates. The authors are aware of several recent cases where supposedly ‘asbestos-free’ aggregate and BS 3882:2007-compliant topsoil has later proven to contain asbestos fibres or ACMs. Indeed, some topsoil and secondary aggregate suppliers have employed disclaimers warning that material may contain up to 0.1 per cent asbestos.

Developers and landowners currently importing soil and aggregate (as part of remedial schemes or otherwise) should have due regard to possible asbestos contamination as such certification may provide only limited defence where strict liability applies. For example, it may be appropriate to test all imported materials, even those previously certified, to demonstrate their suitability for use at the site.

15.7 dOCumentInG the pReSenCe Of ASbeStOS-COntAInInG SOIlS

Following the soil risk assessment and/or remediation process, ACSs can remain on-site under a variety of situations, including:

�� where a soil risk assessment has demonstrated that, although asbestos is present, remediation is currently not justified

�� where ACSs have been left in situ

�� where cover or capping systems have been employed

�� where ACSs (treated or untreated) have been reused

�� where imported soils are not necessarily free of asbestos.

Where such ACSs are known to be present at non-domestic premises, CAR 2012 requires adequate documentation to ensure that inadvertent exposure to asbestos can be prevented and exposures during subsequent planned disturbance of the soils can be controlled and managed. However, there is currently no guidance on how the presence of ACSs should be recorded.

Full details of the ACSs, including the location and depth, asbestos type, form, condition and concentration etc should be recorded. The appropriate documents could include one (or more) of the following:


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1 Asbestos register: an asbestos register is required under CAR 2012 for any non-domestic premises where asbestos is present. The relevant duty holder is then required to formulate an asbestos management plan, which describes how future exposure will be managed and controlled. Although legally a ‘premises’ includes the surrounding soils, ACSs are currently not routinely recorded in asbestos registers. It would, however, be good practice to store information on asbestos in soils alongside the asbestos register as this will minimise the likelihood of future inadvertent exposure.

The requirement under CAR 2012 for an asbestos register applies specifically to non-domestic premises. However, employers must protect employees from asbestos when working in domestic premises. It would be good practice to store information on asbestos in soils relevant to domestic premises where it would be available to employers who may have to undertake ground works in the future (eg building an extension, repairing drains).

3 Health and safety file: under CDM, a health and safety file will be prepared following construction of the owners/occupiers of any commercial or industrial premises. This should include documentation adequately recording the presence of any ACSs. This CDM requirement does not apply to residential redevelopment.

4 Contaminated Land Register: where properties have been determined under Part 2A, details of any ACSs remaining (subsequent to the relevant remedial actions) must be recorded in the Authority’s Contaminated Land Register.

Any investigation, assessment and remediation of ACSs will generate a variety of reports, documents and letters etc. These are likely to include the relevant information but as the availability of these documents to the relevant owners and duty holders cannot be guaranteed, they should not be relied upon as an adequate record of ACSs under CAR 2012.

At redevelopment sites involving privately-owned residential properties, alternative means to adequately document the presence of ACSs should be sought. This may involve notices in the deeds to the property, which would ensure that next, and future, home-owners are aware of the ACSs and can make appropriate decisions regarding its disturbance (eg during home-improvement works). Such declarations may have an impact on property values, but failing to document and adequately communicate these facts could also result in future liabilities for developers.

15.8 AddItIOnAl lIAbIlIty tRAnSfeR meChAnISmSWhere there is any doubt about the long-term integrity or success of the remedial solution, particularly where ACSs remain on-site, interested parties may wish to consider further liability transfer arrangements, such as insurance products. For example, specialist asbestos-related environmental impairment liability insurance is available to cover non-negligent residual post remediation costs.

This is true for any contaminated land clean up, but is likely to be particularly relevant to ACSs due to the nature, and public perception, of the risks involved and the increasing frequency of litigation in relation to alleged asbestos exposure. Further guidance has been provided by Finnamore et al (2000) and Heasman et al (2011).



Summary

�� remedial options for ACSs are limited, but a range of potentially applicable techniques are available in the UK

�� compliance with the CAR 2012 is a critical factor in developing the remedial strategy

�� where permitted by the soil risk assessment, ACSs may be left in situ, or reused following on-site treatment, but adequate documentation is needed to ensure exposure to such soils is suitably controlled in the future

�� off-site disposal to landfill may be the only practical solution at some sites but will require compliance with the prevailing waste legislation and may be expensive

�� careful verification is likely to be critical in maintaining public confidence in the remedial process

�� care should be taken when importing soils and aggregates as asbestos is a common contaminant, even in certified materials

�� any residual liability relating to ACSs can be addressed using financial liability transfer mechanisms, such as insurances.


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16 Risk communication

It is important to be aware that, understandably, the possibility of asbestos in soil can cause alarm. Much of the public is well aware that asbestos is dangerous, due to extensive publicity. Indeed, asbestos has regularly featured in the popular press in human interest stories, and continues to do so.

Some types of risk have characteristics that make them much more alarming whereas some risks are accepted as part of daily life. The risks from asbestos relate to disease that may occur many years later, the level of exposure and risk are difficult to assess for the lay person, and any risk from environmental exposure may be seen as being imposed without consent. These are characteristics that make risks difficult to accept. Publicity about asbestos is often aimed at making workers careful to prevent exposure. The phrase “one fibre may kill” is no longer considered scientifically justified, but has often been quoted in the popular press and is a memorable phrase that remains part of the public perception. The risks from a low level of exposure, including that from asbestos in soil, may be extremely small but that does not make them readily acceptable to those subjected involuntarily to the risks. The HSE publicity (aimed at workers) refers to asbestos as the “hidden killer” and that is a realistic description of the hidden presence of ACMs and the respirable airborne fibres that are invisible to the naked eye (see Useful websites). In preparing communications, it is important to appreciate that environmental exposure to asbestos is difficult for the lay person to assess.

It is very important to take the public perception of asbestos and asbestos-related risks into account when dealing with land containing asbestos.

The estimated magnitude of risk does not necessarily determine the relative importance that people will attach to risks from asbestos. This is very much the case when asbestos is compared to risks from other hazards (see Box 17.1).

Asbestos-related diseases are very unpleasant, painful, slow causes of death. A small risk – if it eventuates – is devastating to the individual and their relatives. For those subjected to exposure to asbestos, the perceptions of asbestos-related risks can result in significant anxiety and stress, which should be treated with due care and respect. Public concerns, regarding environmental asbestos from a site, may include:

�� future health impacts on residents and their families, especially for their children

�� property blight and loss of asset value

�� the potential cost of remediation (under Part 2A)

�� job security if businesses are forced to close.

Good communication that effectively explains low levels of risk related to ACS can help to minimise stress-related health impacts, which are themselves important.

AimThis chapter discusses the potential implications of identifying asbestos in soils at a site and good practice approaches to communicating the potential risks to the public and other stakeholders.



Box 16.1 Risk perceptions (after SNIFFER, 2010)

16.1 pOtentIAl blIGht, COmmeRCIAl lIAbIlIty And ReputAtIOnAl dAmAGe

The presence of asbestos on a site can have consequences beyond the risk to health. The presence of asbestos, even at very low levels, can lead to public alarm. Also, the possibility that land may be contaminated with asbestos can lead to property blight and reputational damage to companies and organisations associated with the site (eg housing developers, former owners and local authorities).

On development sites, the presence of asbestos can also become a commercial risk, as it may reduce the sale price of properties. Consequently, developers involved in sites where asbestos is present may wish to involve representatives from sales and marketing departments in any decisions relating to the management of asbestos. Finance teams should also be aware of the potential financial liabilities associated with asbestos. Developers should consider that the most cost-effective technical solution may not be acceptable to a company as a whole and that the remediation of asbestos post-development will be much more difficult and costly.

16.2 GOOd pRACtICe In COmmunICAtInG the RISKSGeneral guidance on risk communication has been published by SNIFFER (2010) and NICOLE (Schelwald-vd Kley, 2004).

Giving careful thought to the communication of asbestos-related risks and providing good reliable information are important if undue alarm is to be avoided (see Box 17.2). Communications about the presence of asbestos also need to be timely and respectful of all the issues and interests of the various parties who are involved.

Box 16.2 Risk communication (after Schelwald-vd Kley, 2004)

The assessment of the risks posed by ACSs is technically-challenging and complex. Stakeholders are likely to require a detailed description of the process in accessible language, and the risks communicated in an easy to understand form, if the outcome is to be accepted. However, in some circumstances, there may be merit in remediating to a higher standard than technically necessary in order to minimise the impact on public perception.

A local authority identified that a housing estate had been built over a landfill site. The landfill contained a variety of wastes, including asbestos. In addition to the contamination from the waste placed within the landfill, biodegradation of the waste was generating methane gas. Risk assessments identified that the potential risk posed by the methane gas was greater than the risk posed by the contaminated waste. This was because the waste was encapsulated within the ground, whereas the methane gas was potentially entering people’s homes and posing an explosion risk.

When the information on ground conditions was conveyed to the local community, they were more concerned about the presence of asbestos (rather than methane).

The risk that their families might be affected by a disease at some time in the future was more alarming than the larger, current risk from methane.

One factor may have been that the local residents were well aware of the consequences of exposure to asbestos, through friends and relatives suffering asbestos-related diseases from exposure associated with local industries.

Asbestos-related disease is no longer rare in the UK, with about 4000 deaths annually attributed to asbestos exposure.

Good risk communication led to a positive outcome in the redevelopment of a former asbestos factory in Sweden. The developer reported that the key ingredients to allaying public concerns were to “explain what you are going to do before starting the work; Make sure that all concerned parties receive the same information on the same day; Have a qualified media consultant on the team to check communication messages and give other strategic advice.”

One additional piece of advice for developers might be “then, do what you said you would do”. Unexplained deviations from the plan can cause alarm.


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Box 16.3 Communication strategy, Wolverhampton City Council, UK

In dealing with residential properties with gardens affected by asbestos contamination, Wolverhampton City Council adopted a proactive communication strategy to ensure that the residents would receive reliable information directly from the Council. They involved their in-house media communications department to ensure that the message was communicated clearly and honestly to all residents affected.

Summary

�� the health impacts from the past use of asbestos in the UK have been large, and asbestos-related cancers are now much more common

�� the perception of asbestos-related risks is affected by more than just the simple numerical level of risk. People realise that, although the risk may be small, asbestos-related cancers are terminal for those who contract them

�� Comparison with other risks in normal life can help explain the significance of estimated levels of risk

�� even low concentrations of asbestos in soil have the potential to cause property blight, commercial risks and reputational damage for those involved

�� guidance is available on how to best communicate the risk associated with land contamination to the public. This is particularly important in the case of asbestos in soil

�� communication of the soil risk assessment methodology and the resulting risks will need to be presented in a form accessible to the non-specialist. Communication specialists have a useful role to perform.



17 Appointment of consultants, contractors and specialists

It is essential that the client appoints contractors, consultants and specialists who can ensure that the environmental risks from all potential contaminants, including asbestos, are addressed while complying with all relevant health and safety legislation, including CAR 2012.

Historically, the contaminated land and asbestos sectors have operated relatively independently. They have developed different cultures, skill sets and terminology because of the different legislative requirements. For example, contaminated land specialists assess long-term exposures under environmental legislation, while the asbestos industry is traditionally concerned with the management of occupational asbestos exposure under CAR and other health and safety legislation, with much of the remediation work being concerned with short-term exposures. Currently, the asbestos sector primarily applies its asbestos surveying and analytical skills to buildings, building materials and associated asbestos remediation and removals, not to ACSs. The successful investigation, assessment and management of ACSs at many sites will require skills, knowledge and experience from both sectors but the exact mix of skills required will differ from site to site.

At lower risk sites where only small amounts of asbestos may be present, contaminated land practitioners with appropriate experience and training may be able to adequately investigate, assess and manage any asbestos-related risks, either alone or with the guidance of an asbestos specialist. However, at sites where asbestos is a major contaminant of concern, a multidisciplinary team involving both contaminated land and asbestos professionals may be required. It should also be remembered that if any of the tasks are LW, licensed contractors will also be required.

17.1 ISSueS tO COnSIdeRA DETR (1997) report on quality in contaminated land consultancy services recognises that:

�� the removal of asbestos is an example of a specialist service

�� the procurement of quality consultancy revolves around adequately defining, and managing the services required.

So, clients will need an outline understanding of the principles described in this guide in order to develop an appropriate scope of works before procuring services relating to ACSs. Clients, landowners and developers should also remember that all work that may disturb asbestos must be carried out in accordance with CAR 2012 (see Section 3.1.1 and Chapter 8), which places some duties directly on clients.

Clients should seek to appoint consultants and contractors who can demonstrate that they can successfully fulfil this scope of works. Clients need to look for evidence of relevant training, qualifications, experience and competences (see Section 17.2) in the information supplied by candidates. However, it should be remembered that, at most sites, asbestos will be one of many contaminants, all of which should be adequately addressed as part of the investigation and assessment.

AimThis chapter is intended to help clients ensure they procure the right combination of land contamination and asbestos investigation, assessment and remediation skills. Regulators will also benefit from an enhanced awareness of the range of expertise that ought to have been deployed in preparing reports submitted to them.


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There remain considerable scientific knowledge gaps and uncertainties in the understanding of the release of asbestos fibres from soils and made ground and also in the assessment of the risks they pose. While it is essential to have due regard to the health risks and uncertainties, there may be a tendency for some consultants and contractors to adopt overly cautious assumptions and precautionary approaches to the assessments of ACSs. It is important that any assessment is balanced, proportionate and transparent. To be robust and scientifically valid it should take full account of the extent and nature of any asbestos contamination, the nature of the ACMs, the site situation and the current or proposed use of the site.

Clients need to consider the track record of candidates and may wish to follow up on references relating to similar projects involving ACSs. Clients should also consider their attitude to commercial risk, which is not defined by current scientific knowledge. Risk-averse clients can either adopt more cautious and costly approaches with respect to asbestos or consider the use of additional risk transfer mechanisms, such as environmental insurances.

17 .1 .1 InsuranceOrganisations working in both the contaminated land and asbestos sectors should carry appropriate insurances, including those covering employer’s liability and professional indemnity. However, it is important to note that such insurance can have a variety of limitations, such as maximum values (individually or in the aggregate) and may exclude certain activities. Importantly, some insurances may specifically exclude asbestos-related work. Clients should ensure that all insurances offered are valid and specifically include the type(s) of tasks with ACSs that are proposed.

17.2 COmpetenCIeSLike other jurisdictions, the UK does not have a means of independently accrediting or certifying the skills, experience and competencies of those working with ACSs.

Examples of the range of competencies relevant to the investigation and assessment of three generic scenarios of sites are presented in Table 17.1. This may assist clients in ensuring that they appoint suitable consultants to assess the potential risks posed by ACSs. However, the competencies required for any remedial works will need to be considered case-by-case based on the conclusions of the site assessment report, the nature of the remedial measures to be implemented and the nature of the site (ie size, location and type of neighbouring properties).

17 .2 .1 Contaminated land competenciesCompetence in the assessment of land contamination is essential at all sites, whether asbestos is likely to be present or not. Competence in land contamination can be demonstrated by a combination of experience and relevant professional qualifications. A spectrum of skills is needed. For example, initially site walkovers can require general awareness of what to look for as well as how to protect oneself and then as the stage of work progresses the specialist knowledge levels should be increasing along relevant lines.

Many professional bodies are relevant to land contamination management (Nathanail, 2013). There are two professional qualifications explicitly in land contamination. A registered Specialist in Land Condition (SiLC) is a chartered senior practitioner who has a broad awareness, knowledge and understanding of land condition issues, providing impartial and professional advice in their field of expertise. Engineers and geologists on the Register of Ground Engineering Professionals (RoGEP) who list contaminated land expertise as one of their main areas of expertise have a professional qualification in land contamination. Some highly experienced senior practitioners have no professional qualification.

The technical abilities and experience of contaminated land practitioners in the UK varies greatly. It is important that consultants and contractors appointed to work with ACSs are able and knowledgeable. In particular, they should appreciate the current state of knowledge regarding the risks posed by ACSs



and resulting uncertainties in any soil risk assessment. Less able consultants may adopt unreasonably cautious assumptions in response to such uncertainties, which may result in unnecessary public concern and remedial costs.

Specific competences needed to investigate any potentially contaminated site, including those affected by asbestos, include:

�� knowledge of the relevant legal context and associated guidance (such as Part 2A or redevelopment regimes in the appropriate country)

�� knowledge of relevant good practice guidance and industry standards, such as BS 10175:2011+A1:2013 and CLR11

�� knowledge and experience of relevant health and safety regulations (eg CDM) and appropriate control measures and PPE etc

�� experience in conducting a PRA and developing an initial CSMs outlining the potential contaminant linkages

�� experience in designing suitable sampling and analytical strategies that will meet the data quality requirements of the investigation

�� experience in the safe supervision of site works, including the installation of gas and groundwater monitoring installations

�� ability to collect high quality soil, water, and other environmental samples for subsequent analysis and in situ monitoring of ground gas and groundwater regimes

�� experience in exposure assessment and risk evaluation for all non-asbestos contamination

�� knowledge of available remedial options relating to non-asbestos contaminants.

17.2.2 Asbestos-relatedcompetenciesThe competencies of an asbestos specialist will become increasingly important as the potential asbestos risks increase (ie greater amounts of asbestos, the presence of friable or degraded ACMs or free asbestos fibres and/or the presence of amphibole asbestos). There are a range of recognised technical and professional proficiency modules and qualifications within the asbestos industry. Currently none of these, on their own, can demonstrate overall competence in the investigation, assessment and management of ACSs. However, they are prerequisites for demonstrating competence in activities such as air monitoring, identification of ACMs and the application of CAR 2012 to investigation and remediation works. Asbestos specialists may be needed solely to provide occupational health and safety support to contaminated land practitioners (eg advice on CAR 2012 compliance or to undertake occupational air monitoring) and, where deemed necessary, to spot ACMs on the surface or in large soil samples before coning and quartering. However, at complex sites, they may be an integral part of a multidisciplinary team undertaking various types of air monitoring, collecting and analysing indoor dust or air monitoring, assessing likely exposures, and predicting and interpreting potential risks.


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Table 17.1 The range of asbestos-related competencies potentially needed by consultants, and consortia, investigating and assessing the risks posed by ACSs at contaminated sites for three illustrative scenarios

Scenario 1: sites where low levels of asbestos may be present in soils and made ground. It is assumed that asbestos is not a significant contaminant of concern but that some asbestos may be present and that a simple risk assessment based primarily on the presence/absence of ACMs in soils will be sufficient.Scenario 2: sites where only moderate levels of asbestos cement (or very small amounts of chrysotile fibres) are likely to be present in soils and made ground. It is assumed that, in addition to other substances, asbestos may be a significant contaminant of concern and that a qualitative or semi-quantitative risk assessment based on the asbestos types, the ACMs present, condition, depth and concentrations of asbestos will be sufficient.Scenario 3: sites where significant levels of asbestos (including crocidolite and amosite) are likely to be present in soils and made ground. It is assumed that asbestos is a significant contaminant of concern and that a full quantitative risk assessment based on a ‘lines of evidence’ estimate of airborne asbestos concentrations will be required.

Asbestos-related competencies or ability within the investigative team: Scenario 1 Scenario 2 Scenario 3

Able to produce a suitable and sufficient CAR risk assessment 3* 3* 3*

All site staff. and managers, have appropriate asbestos awareness training 3* 3* 3*

Evidence of appropriate insurances that include asbestos-related liabilities 2 3 3

Knowledge and experience in identifying potential ACMs within soils and made ground 3 3 3

Experience in designing sampling and analytical strategies suitable for the assessment of ACSs, taking account of the likely hazards, relevant uncertainties and heterogeneity issues

3 3 3

Experience in the safe supervision of works involving ACSs, including appropriate control measures, RPE and PPE requirements 3 3 3

Ability to safely collect, label, package and dispatch samples of suspected ACM and/or asbestos-containing soil for laboratory analysis 3 3 3

All identification of asbestos in soil will be UKAS accredited 3* 3* 3*

All quantification of asbestos in soil will be UKAS accredited 3 3 3

All occupational air monitoring (both sampling and PCOM analysis) will be UKAS accredited 1* 2* 3*

Awareness of the ‘toolbox’ of other techniques and tests that can inform estimates of asbestos exposure 1 2 3

Experience, and preferably UKAS accreditation, for environmental air monitoring 1 2 3

All identification and quantification of environmental air monitoring (PCOM, SEM or TEM) will be UKAS accredited 1 2 3

Sampling and analysis of settled dust samples 1 1 2

Knowledge and experience of estimating potential cumulative exposures relating to ACSs 1 2 3

Knowledge and experience of applying asbestos exposure-risk models to ACSs – including an appreciation that if overly cautious assumptions are adopted the resulting risk estimates will be unrealistic

1 2 3

Key

1 = unlikely to be required2 = probably required3 = definitely required* = mandatory under CAR, if needed.

notes

1 CAR must be complied with on all sites during all activities that may disturb asbestos.2 The exact requirements of health risk assessments should be ascertained on a site by site basis. The requirements will depend, as

appropriate, on site location, site use, surveying procedures, remediation methods and current and future site use. eg Sites in sensitive areas that will be used for domestic properties with gardens may require more comprehensive site investigations.

3 These competencies and abilities are in addition to basic contaminated land competencies (Section 9.2.1) needed for all sites


147Asbestos in soil and made ground

Summary

�� any contaminated land risk assessment should consider all potential contaminants of concern, which may include asbestos

�� where asbestos is a potential contaminant of concern, additional skills, experience and competencies may be required in order to adequately investigate and assess the potential risks while complying with CAR 2012

�� contaminated land practitioners will be needed at all sites, but may require varying degrees of input from asbestos specialists depending on the nature of the site

�� significant input from asbestos specialists may be required at sites were asbestos is a major contaminant and/or the type(s) and form of asbestos present may pose elevated levels of risk. Such sites may best be addressed by a multidisciplinary team rather than an individual consultant

�� clients need to provide a clear specification for the investigation, including its aims and scope of works, and look for evidence that the appointed contractors have the relevant training, knowledge, competencies and experience appropriate for the site under consideration

�� the client, consultant(s) and contractor(s) should work together as a team with a common goal. Handing the responsibility of a complex investigation entirely to the consultant and letting them ‘get on with it’ can lead to disappointment and friction.


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18 Conclusions and recommendations

The preparation of this guide has involved reviewing all the issues relevant to dealing with asbestos affected land and discussions of drafts with the project steering group. The body of information in this guide will help stakeholders increase their confidence in and improve the quality of risk management on sites that contain soils or made ground potentially contaminated by asbestos.

There are a number of conclusions regarding the current situation.

18.1 COnCluSIOnS

18 .1 .1 Historical asbestos legacy for redevelopment sites in the UK (Chapters4and11)

Asbestos was used in huge quantities in the UK in the 20th century, and in a wide variety of materials. Many of these materials were used in the fabric of buildings or the insulation of industrial plant and equipment, until all sale or installation of asbestos was essentially banned in 1999.

Redevelopment of brownfield sites and industrial processes has led to asbestos contamination of ground at many sites. However, the extent of this contamination is not known.

Asbestos contamination is very durable and it will remain in soil indefinitely. Many common ACMs may degrade in the soil environment, releasing durable asbestos fibres into the soil. The rates of such deterioration and release are unknown.

18.1.2 Healthrisksfromasbestos(Chapter5)Asbestos only poses a risk to health if and when fibres become airborne and are inhaled.

The health risks potentially posed by environmental exposures, such as those that may be generated under some circumstances by ACS, are mainly limited to lung cancers and mesothelioma.

The epidemiological evidence linking asbestos exposure with these diseases is very robust.

Scientific understanding of the risks from low level exposure to asbestos has continued to develop and there is strong evidence that it poses a small, but real risk to health.

Chrysotile asbestos is less potent than amosite, which in turn is less potent than crocidolite, but all forms can result in fatal disease (see Boxes 14.2 and 14.3).

18.1.3 Regulationofworkwithasbestos(Chapter8)CAR 2012 applies to all site reconnaissance visits, site investigations and remediation projects where asbestos, ACMs or ACSs will be disturbed.

To comply with CAR, a suitable and sufficient risk assessment must be completed for every task. It should be proportionate to the task and the risk posed by the land.

This risk assessment is also the key to identifying what, if any, control measures, PPE and RPE may be required and if some or all activities are deemed LW, NNLW or NLW under CAR.



CAR also requires that appropriate health and safety training must be provided for all those who may be exposed, including asbestos awareness training. Additional proficiency training may also be required.

The expectations and standards for preventing and controlling exposure to asbestos have become ever tighter over the past 50 years. Developments in Europe suggest that standards will continue to tighten.

Unfortunately, the extensive past use of ACMs has meant that many sites in the UK are affected by the presence of asbestos. Levels of asbestos contamination that might have been ignored in the past are now recognised as significant.

18 .1 .4 Preliminary risk assessment and developing the conceptual sitemodel(Chapter10)

The principles behind the PRA and the CSM are the same as those used for any other chemical contaminants.

The potential for ACSs to be present should be considered during the PRA at all sites. This potential and the likely type of asbestos, form of material and amounts of such materials should be adequately considered using factors such as the age and history of the demolished structures and when the demolition occurred.

For sites where asbestos may be present, additional sources of information should be sought and consulted as part of the desk study.

Site reconnaissance surveys should be undertaken by appropriately experienced and trained personnel capable of identifying potential ACMs, even when the ACMs are in fragments, have deteriorated, or are smeared with soil etc. These surveys may include limited sampling of soils or suspected ACMs. Significant amounts of asbestos fibres or ACM may be present but not visible.

A site reconnaissance cannot rule out the presence of asbestos, but can only confirm that it is present.

The PRA and CSM should provide sufficient information to identify any potential contaminant linkages involving asbestos. Contaminant linkages require the presence of a potential sources, valid route(s) of exposure (ie mechanisms that can release airborne asbestos fibres), and potential receptors (ie residents, workers, the public). Assessing the overall significance any potential linkages forms the basis for deciding whether further site investigations in relation to asbestos are necessary and, if so, the nature and extent of these investigations.

18.1.5 Samplingandanalysisofsoilsamples(Chapter12)Soil sampling and analysis should be carried out with due consideration of the purpose for which the resulting data will be used.

Standard intrusive techniques can be used for asbestos in soil. However, selecting appropriate procedures will require consideration of the site under investigation, the special requirements arising from the immobility of asbestos in soils and the specific asbestos health and safety issues.

CAR 2012 requires all analysis to identify asbestos in soils to be conducted using UKAS accredited methods.

The analysis needs to have adequate sensitivity. Detection and quantification limits should be no more than 0.001 per cent. The precise analytical method adopted should be appropriate for the purpose of the investigation.

Methods of asbestos identification based on the PLM method in HSG248 (HSE, 2005) are appropriate for analysing asbestos in soils.


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Quantification of asbestos in soils is normally only necessary if it is deemed that a quantitative health risk assessment may be required. Satisfactory quantification of asbestos in soils can sometimes be achieved using optical microscopy techniques (including PLM and PCOM) to pick and weigh ACM fragments and fibre bundles alone, but additional quantification of free fibres may be necessary. Electron microscopy (ie SEM and TEM) is rarely justified for soil samples. Laboratories selected for this work should have UKAS accreditation for quantifying asbestos in soils.

Reports of identification of asbestos in soils and of quantitative analysis of asbestos should report the nature of any ACMs present as well as the types of asbestos found and, where appropriate, the amounts present.

18.1.6 Airmonitoringandanalysisofasbestosinair(Chapter13)Where ACSs are present, ambient and occupational air monitoring may provide data relevant to supporting a robust soil risk assessment.

Occupational asbestos in air monitoring is covered by CAR 2012 and is well described in HSG248 (HSE, 2005) and on the HSE website (see Useful websites).

Depending on the objectives, monitoring may be of outdoor air or indoor air (where soil-derived asbestos may have been tracked back into buildings).

Any monitoring and analysis must be conducted in-line with CAR 2012 and by a suitably accredited organisation.

Sampling methods for monitoring non-occupational exposures may be different to those generally used for occupational hygiene and described in HSG248 (HSE 2005).

Detection limits for environmental and indoor air monitoring need to be of the order of 0.00001 f/ml to assess the risks from ACSs to the health of neighbours and building occupants. This requires long sampling periods.

Outdoor asbestos in air monitoring in wet weather will produce very low concentrations in almost all situations. If ambient air monitoring is to be used as the main source of air concentrations for exposure determination in any risk assessment, some monitoring in dry conditions is necessary.

PCOM is suitable for the occupational health monitoring and compliance monitoring required by CAR 2012. PCOM alone cannot discriminate between fibre types. So, it may produce false positives and is not suitable for environmental asbestos in air monitoring designed to support bystander risk assessments.

Electron microscopy methods (ie SEM or TEM) are likely to be required for sample analysis to achieve the specificity and low detection limits required for monitoring environmental situations.

18.1.7 Exposureestimation(Chapter14)Environmental exposure assessment and quantitative soil risk assessment only becomes necessary if there is sufficient evidence from soil analysis and/or air monitoring to cause concern or uncertainty regarding current or future health risks.

The risks to human health from airborne asbestos are related to cumulative exposure, which is determined by the magnitude and duration of exposure(s).

Cumulative exposure is expressed in fibre/ml.hours or as fibre/ml.years.

A conceptual exposure model should be defined describing all reasonably likely exposures and other factors likely to influence exposure.



All relevant sources from the contaminated soil should be considered in the exposure assessment. Possible exposures from outdoor activities in the contaminated area such as estate management work or playing, presence outdoors in the contaminated area and indoor exposures from tracked back asbestos should all be included.

Proper account should be taken of different weather and ground conditions during the different seasons.

Estimated concentrations may be calculated from air monitoring, ‘fibre release potential’ tests or from soil concentrations using predictive modelling. A ‘lines of evidence’ approach involving more than one may be required for robust risk estimation.

The method used to estimate exposure, inherent limitations, the conceptual exposure model assumed and the estimated exposures should be clearly presented in any report.

18.1.8 Riskestimationandevaluation(Chapter15)There are currently no suitable generic assessment criteria for assessing the significance (for risk to health) of asbestos in soil in the UK.

Due to the limited current understanding of the soil-to-air relationships for asbestos and ACMs, it is inappropriate to attempt to calculate any such generic assessment criteria for concentration of asbestos in soil.

The most scientifically-valid approach to assessing the risks from asbestos in soil is to estimate potential cumulative exposures to airborne fibres and calculate the associated risks using exposure-risk models. A detailed quantitative risk assessment using this approach should be undertaken where a qualitative assessment shows that the exposures may be of concern.

Exposure-risk models available for asbestos will predict the likely health effects of exposure to airborne asbestos. However, extrapolation of the available models over many orders of magnitude means that resulting risk estimates are indicative only and should not be used as accurate absolute values.

A simple procedure for employing the model derived by Hodgson and Darnton (2000) to assess exposures from soils has been presented.

Decisions or recommendations regarding the acceptability or unacceptability of the estimated risks produced need to take full account of the uncertainties involved.

Any reports should fully describe and justify the assessment process used and the uncertainties, with reference to the specific legal context (eg planning, Part 2A or civil liability).

18.1.9 Remediationandmanagement(Chapter16)Remedial options for ACSs are limited, but a range of potentially applicable techniques are available in the UK.

Compliance with CAR 2012 is a critical factor in developing the remedial strategy.

Careful verification is likely to be critical in maintaining public confidence in the remedial process.

Where permitted by the soil risk assessment, ACSs may be left in situ, or reused following on-site treatment, but adequate documentation is needed to ensure exposure to such soils is suitably controlled in the future.

noteThe hazardous waste threshold (see Section 3.6) and the value of 0.001 per cent (asbestos in soil) mentioned by ICRCL (1990) should not be used as indicators of acceptability of risk.


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Off-site disposal to landfill may be the only practical solution at some sites but will require compliance with the prevailing waste legislation and may be expensive.

Care should be taken when importing soils and aggregates as asbestos is a common contaminant, even in certified materials. Test certificates should be checked to ensure the limits of quantification are appropriate.

Verification reports are a vital record of any remedial intervention but this is particularly important for the treatment of ACSs. It is vital that adequate records of the types, depths and locations of any ACSs remaining on-site are kept within these reports or in other official documentation to prevent future exposures during subsequent earthworks at the site.

Any residual liability relating to ACSs can be addressed using financial liability transfer mechanisms, such as insurances.

18.1.10Riskcommunication(Chapter17)Even low concentrations of asbestos in soil have the potential to cause community concerns, property blight, commercial risks and reputation damage for those involved.

Extensive guidance has been published on how to best communicate the risk associated with land contamination to the public. This is particularly important in the case of asbestos.

In some instances, regular, open, honest and clear communications with the local community are essential.

Communications on the soil risk assessment methodology and the resulting risks will need to be understandable and in plain English if public support is to be maintained.

The involvement of qualified public relations and media consultants should be considered for complex and/or sensitive situations.

18.2 ReCOmmendAtIOnS fOR fuRtheR develOpmentSThe following further developments are recommended.

18.2.1 HazardclassificationofACSsandwhenCAR2012willapplyto such soils

Given the ubiquitous reference to asbestos in all DoE’s industry profiles (see Section 11.2), it is impossible to guarantee that the soils at any given site are completely free from asbestos. In particular, clarifying the definition of ‘trace’ quantities of asbestos would be particularly helpful. It is understood that this issue is currently being reviewed by the Joint Industry Working Group Asbestos in Soil, Made Ground, Construction and Demolition Materials (JIWG) in conjunction with the HSE (note that because the quantification method is slightly different from that for identification, the detection limit and quantification limits may be the same). In the longer term, a matrix or checklist approach, which would allow a ‘site score’ to be produced from the desk study information and/or site investigations may be appropriate. It will be difficult to future-proof such an approach given the lack of data on the deterioration of ACMs in soils (see Section 18.2.2).

18 .2 .2 Guidance on LW and NLWThe existing guidance on what constitutes LW appears to be based on what is needed for ACMs in buildings. There has been less practice in applying the guidance to ACMs or asbestos fibres in soils. This is an area where expansion of guidance to include ACSs explicitly would assist the development industry.



18 .2 .3 Adapting laboratory analytical reports to suit the purpose of quantitative site risk assessment

Ensure laboratory analysis reports for asbestos in soil provide sufficient detail to inform an adequate risk assessment. The conclusions (Section 18.1) state the requirements.

18 .2 .4 Fibre releasability database The information produced by Addison et al (1988) (on release of fibres from soils, and on the effect of moisture content) and by Burdett (undated) (on relative release of fibres from ACMs) provides a basis for making estimates of the likely release of fibres from soils that contain asbestos or ACMs. There may well be a benefit in extending the database to a wider range of soil types (including made ground and aggregates) containing a more representative range of ACMs and asbestos.

18.2.5 Commercialfibrereleasetestingforsite-specificsoilThere may be requirement, and it has been used in a case study described in this guide (see Case study A2.3). However, it is a time consuming and costly test, and would require testing large numbers of samples to take adequate account of variation in the amount and type of ACM in soil samples. The asbestos content would also need to be quantified to verify the consistency. It may be worth examining the feasibility of making it a commercial test. Such testing is unlikely to be used routinely.

18 .2 .6 Current background concentrations of asbestos in air and soilsCurrent data on background airborne asbestos concentrations in different parts of the UK would be of significant use in comparing potential risks from soil sources with ubiquitous environmental exposures.

Data on the levels of asbestos in soils, particularly in urban environments, should be collated to indicate the scale and extent across the UK. However, it is acknowledged that there will be difficulties in comparing data or deriving quantitative summaries due to the range of soils analysis employed historically and the extreme heterogeneity encountered. Such data would not demonstrate that such concentrations are ‘safe’ or acceptable under planning. In England and Wales, such data may be of use in defining ‘normal background concentrations’ that could assist decision making under Part 2A.

18 .2 .7 Using Dutch research on negligible risk levelsIn the UK, no threshold comparable to the Dutch ‘negligible risk’ level has been set for the protection of the UK population from long-term non-occupational environmental exposures to airborne asbestos. There would be value in using the research behind the Dutch levels to develop values appropriate to the UK.

18 .2 .8 Software implementation of modelsSoftware implementing the exposure-risk models recommended for use in the UK should be developed and made available to the contaminated land community to support site-specific soil risk assessments. However, the use of such software requires significant scientific expertise and additional training for risk assessors.

18 .2 .9 Appropriate record keeping on the presence of asbestos in soilsThere is no doubt that the presence of ACSs needs to be adequately recorded in order to ensure the safety of residents and workers post-development. Consideration should be given to the appropriate places to record this information.


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18.2.10Betterunderstandingoftheriskfromlowlevelsofnon-occupational exposure

More research is needed to understand the risks relating to chronic non-occupational exposure to low levels of airborne asbestos and so reduce reliance on extrapolation from higher levels of occupational exposure.

18.2.11Comparativestudiestodefinecosteffectivemethodsandrequirements for environmental monitoring

Comparative studies are needed to determine the feasibility, cost and benefits of different monitoring techniques in the assessment of environmental exposures. This will help practitioners choose the appropriate approaches and understand the uncertainties in the resulting data.



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HSE (2012a) Mesothelioma mortality in Great Britain 1968-2010, Health and Safety Executive, Sudbury, UK. Go to: www.hse.gov.uk/statistics/causdis/mesothelioma/mesothelioma.pdf

HSE (2012b) Disposal of asbestos waste, EM9 Health and Safety Executive, Sudbury, UK. Go to: www.hse.gov.uk/pubns/guidance/em9.pdf

HSE (2012c) How to deal with fly-tipped asbestos waste, Asbestos Essentials (a38), Health and Safety Executive, Sudbury, UK. Go to: www.hse.gov.uk/pubns/guidance/a38.pdf

HSE (2012d) Contractors failed to alert workers to presence of asbestos, HSE SE/184/12. Health and Safety Executive, Sudbury, UK. Go to: www.hse.gov.uk/press/2012/rnn-se-18412.htm

HSE (2013a) Managing and working with asbestos – Control of Asbestos Regulations 2012: Approved Code of Practice and guidance, L143 (second edition), HSE Books, Health and Safety Executive, Sudbury, UK (ISBN: 978-0-71766-618-8). Go to: www.hse.gov.uk/pubns/books/l143.htm

HSE (2013b) Respiratory protective equipment at work: A practical guide, HSG53, Health and Safety Executive, Sudbury, UK. Go to: www.hse.gov.uk/pubns/books/hsg53.htm


CIRIA, C733160

IARC (2012) Arsenic, metals, fibres, and dusts, International Agency for Research on Cancer, Lyon, France (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 100C). Go to: monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-11.pdf

ICRCL (1990) Asbestos on contaminated sites (second edition), Guidance Note 64/85, Interdepartmental Committee on the Redevelopment of Contaminated Land, London, UK

IMRAY, P and LANGLEY, A (2001) Health-based soil investigation levels, enHealth Council, Wueensland Department of Health, Australia (ISBN: 0-73085-674-7). Go to: http://tinyurl.com/pljm678

JEFFRIES, J and MARTIN, I (2009) Updated technical background to the CLEA model, Science Report: SC050021/SR3, Environment Agency, Bristol, UK (ISBN: 978-1-84432-856-7). Go to: http://tinyurl.com/qdeu3bb

JOHNSON, C C, ANDER, E L, CAVE, M R and PALUMBO-ROE, B (2012) Normal background concentrations (NBCs) of contaminants in English soils: Final project report, Science Facilities Directorate, British Geological Survey, Commissioned Report CR/12/035, Department for the Environment, Food and Rural Affairs, London

JOHNSTON, R and MCIVOR, A J (200) Lethal work: a history of the asbestos tragedy in Scotland. Tuckwell Press Ltd, Edinburgh (ISBN: 978-1-86232-178-6)

JONES, A, CHERRIE J, COWIE, H and SOUTAR, A (2005) An assessment of risks due to asbestos on farm tracks and rights of way in South Cambridgeshire, Research Report TM/05/07, Institute of Occupational Medicine, Edinburgh, UK

LEE, R J and VAN ORDEN, D R (2008) “Airborne asbestos in buildings” Regulatory Toxicology and Pharmacology, vol 50, 2, Elsevier BV, UK, pp 218–225

LOOMIS, D, DEMENT, J M, WOLF, S H and RICHARDSON, D B (2009) “Lung cancer mortality and fibre exposures among North Carolina asbestos textile workers” Occup Environ Med, vol 66, 8, School of Community Health Sciences, University of Nevada, USA, pp 535–542

MADEP (2007) Asbestos-in-soil: Draft final regulations and policy, Massachusetts Department of Environmental Protection, Boston, MA. Go to: www.mass.gov/dep/service/regulations/proposed/aisfindr.pdf

MCELVENNY, D M, DARNTON, A J, PRICE, M J and HODGSON, J T (2005) Mesothelioma mortality in Great Britain from 1968 to 2001, Occup Med (Lond), vol 55, 2, Health & Safety Executive, Bootle, UK, pp 79–87

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OSHA (1974) PART 1910 Occupational Safety and Health Standards, Appendix B to 1910.1001, Detailed procedures for asbestos sampling and analysis – non-mandatory. Go to: http://tinyurl.com/q5myrqy

OTNESS, P, FELDWICK, M and DI MARCO, P (2003) “Asbestos - Recent developments and implications for health policy”. In: Proc of the fifth national workshop on the assessment of site contamination, A Langley, M Gilbey and B Kennedy (eds), May 2002, NEPC Services Corporation, Adelaide, Australia, (ISBN: 0-64232-355-0), pp 243–252

PETO, J, HODGSON, J T, MATTHEWS, F E and JONES, J R (1995) “Continuing increase in mesothelioma mortality in Britain” The Lancet, vol 345, 8949, Institute of Cancer Research, Surrey, UK, pp 535–539



PETO, J, RAKE, C, GILHAM, C and HATCH, J (2009) Occupational, domestic and environmental mesothelioma risks in Britain: A case-control study, HSE RR696, HSE Books, Health and Safety Executive, Sudbury, UK. Go to: www.hse.gov.uk/research/rrpdf/rr696.pdf

RAKE, C, GILHAM, C, HATCH, J, DARNTON, A, HODGSON, J and PETO, J (2009) “Occupational, domestic and environmental mesothelioma risks in the British population: a case–control study” British Journal of Cancer, vol 100, 7, Nature Publishing Group, UK, pp 1175–1183

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RIVM (2004) Relevance of human exposure via house dust to the contaminants lead and asbestos, RIVM report 711701037, National Institute of Public Health and the Environment, RIVM, Bilthoven, the Netherlands

ROBERTSON, A, JONES, A, MOORBY, N, CLARK, S, SPINKS, A, DYE, A and DONEY, J (2011) Asbestos contamination in garden soils on the site of the former Courtaulds Dunstall Hall Works, Wolverhampton, IOM report No 629-00300, Institute of Occupational Medicine and Johnson Poole & Bloomer for Wolverhampton City Council

ROSENBAUM, M S, MCMILLAN, A A, POWELL, J H, COOPER, A H, CULSHAW, M G and NORTHMORE, K J (2003) “Classification of artificial (man-made) ground” Engineering Geology, vol 69, 3, Elsevier BV, UK, pp 399–409

RPS CONSULTANTS LTD (1994) Documentary research on industrial sites, R&D Publication CLR3, Department of the Environment, HMSO, London, UK. Go to: www.eugris.info/envdocs/CLR03_00.pdf

SCHELWALD-van der KLEY, A J M (2004) Communication on contaminated land, NICOLE, Schelwald-van der Kley consultancy BV, the Netherlands. Go to: http://tinyurl.com/pj8a383

SCHNEIDER, T, DAVIES, L S, BURDETT, G, TEMPELMAN, J, PULEDDA, S, JORGENSEN, O, BUCHANAN, D and PAOLETTI, L (1998) “Development of a method for the determination of low contents of asbestos fibres in bulk material”, Analyst, vol 123, 6, National Institute of Occupational Health, Copenhagen, Denmark, pp 1393–1400

SCHNEIDER, T, CHERRIE, W, VERMEULEN, R and KROMHOUT, H (2000) “Dermal exposure assessment” The Annals of Occupational Hygiene, vol 44, 7, Elsevier Science Ltd, UK, pp 493–499

SCOTTISH EXECUTIVE (2000) Planning Advice Note (PAN) 33 Development of Contaminated Land (Revised Oct 2000), The Scottish Government, Edinburgh

SCOTTISH EXECUTIVE (2006) Part IIA Contaminated Land Statutory Guidance: Edition 2, Paper SE/2006/44, The Scottish Government, Edinburgh (ISBN: 0-75596-097-1)

SEPA (2005) Asbestos contaminated waste, Special Waste Advisory Note (SWAN/12), v 1.0, Scottish Environment Protection Agency, Stirling, Scotland. Go to: http://tinyurl.com/poswgwf

SHP (2013) “School’s asbestos risk overestimated, new HSL tests find”, Safety and Health Practitioner, The Official Magazine of IOSH, UBM plc, London. Go to: http://tinyurl.com/nw5grra

SHUKER, L, HARRISON, P and POOLE, S (eds) (1997) Fibrous materials in the environment, Institute for Environment and Health (IEH), Leicester, UK (ISBN: 1-89911-017-8)

SMITH, K R and SAUNDERS, P J (2007) The public health significance of asbestos exposure from large-scale fires, HPA-CHaPD-003, Health Protection Agency, Didcot, UK (ISBN: 978-0-85951-607-5)

SNIFFER (2007) Assessment of environmental legislative and associated guidance requirements for the protection of human health, UKCC02, Scotland and Northern Ireland Forum for Environmental Research (Edinburgh, Scotland). Go to: www.sniffer.org.uk/files/9113/4183/7997/UKCC02_Electronic_Project_Summary.pdf

SNIFFER (2010) Communicating understanding of contaminated land risks, UKLQ13, Scotland and Northern Ireland Forum for Environmental Research (Edinburgh, Scotland). Go to: http://tinyurl.com/qe4h99t


CIRIA, C733162

STAYNER, L T, DANKOVIC, D A and LEMEN, R A (1996) “Occupational exposure to chrysotile asbestos and cancer risk: a review of the amphibole hypothesis” American Journal of Public Health, vol 86, 2, American Public Health Association, Washington DC, USA, pp 179–186

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SULLIVAN, P A (2007) “Vermiculite, respiratory disease, and asbestos exposure in Libby, Montana: Update of a cohort mortality study” Environ Health Perspect, vol 115, 4, National Institute of Environmental Health Science, USA, pp 579–585

SWARTJES, F A and TROMP, P (2008) “A tiered approach for the assessment of the human health risks of asbestos in soils” Soil and Sediment Contamination, vol 17, 2, Taylor & Francis Online, UK, pp 137–149

TEDD, P, WITHERINGTON, P, EARLE, D, HOLLINGSWORTH, S, FURLONG, B, BRADLEY, L, MALLETT, H and LAIDLER, D (2004) Cover systems for land regeneration – thickness of cover systems for contaminated land, BRE Report 465, BRE Press, London (ISBN: 1-86081-684-3)

UKAS (2010) Asbestos technical Bulletin – Issue 1, UKASATB001, April 2010, United Kingdom Accreditation Service, Middlesex, UK. Go to: http://tinyurl.com/p93sewt

UKSC (2011) Judgment. Sienkiewicz (Administratrix of the Estate of Enid Costello Deceased) (Respondent) v Greif (UK) Limited (Appellant) Knowsley Metropolitan Borough Council (Appellant) v Willmore (Respondent), UK Supreme Court 10. Go to: http://tinyurl.com/62b7o48

US EPA (1988) Seven cardinal rules of risk communication, OPA-87-020, United States Environmental Protection Agency, Washington DC, USA. Go to: www.epa.gov/care/library/7_cardinal_rules.pdf

US EPA (1997) Superfund method for determination of releasable asbestos in soils and bulk materials (Interim version), EPA 540-R-97-028, United States Environmental Protection Agency, Washington, DC, USA

US EPA (2002) Region 8: Libby Asbestos, United States Environmental Protection Agency, Washington DC, USA. Go to: www.epa.gov/libby/

US EPA (2008) Framework for investigating asbestos-contaminated superfund sites, OSWER Directive#9200.0-68, Technical Review Workgroup Asbestos Committee, United States Environmental Protection Agency, Washington DC, USA. Go to: http://tinyurl.com/q7lwos2

VARNEY, R, BISBEE, G and O’BRIEN, P (2000) Guidance for managing risks asbestos disposal, NHDES-WMD-00-1, New Hampshire Department of Environmental Services, New Hampshire, USA. Go to: http://des.nh.gov/organization/commissioner/pip/publications/wmd/documents/wmd-00-1.pdf

VIRTA, R L (2006) “Asbestos”. In: Kogel, J E, Trivedi, N C, Barker, J M and Krukowski, S T (eds) Industrial minerals and rocks society for mining, metallurgy, and exploration, 7th edition, Society for Mining, Metallurgy, and Exploration, USA (ISBN: 978-0-87335-233-8), pp 195–217

VROM (2000) Circular on target values and intervention values for soil remediation, Ministry of Housing, Spatial Planning and Environment, the Netherlands. Go to: http://tinyurl.com/o5pf8m9

WAGNER, J C (1991) “The discovery of the association between blue asbestos and mesotheliomas and the aftermath” British Journal of Industrial Medicine, vol 48, 6, BMJ Group, UK, pp 399–403

WATSON, G (2007) “Estimating figures for England and Wales”. In: Asbestos surveys in premises and new guidance, ATAC BOHS Seminars 2010. Go to www.bohs.org/uploadedFiles/Events/Past_Events/martin%20gibson.pdf

WEIS, C P (2001) Memorandum: Amphibole mineral fibers in source materials in residential and commercial areas of Libby Pose an imminent and substantial endangerment to public health, United States Environmental protection Agency, Colorado, USA. Go to: http://tinyurl.com/pnhwtnn



WELSH GOVERNMENT (2012) Planning Policy Wales (Edition 5), Welsh Government, Cardiff (ISBN: 978-075048-211-0). Go to: http://wales.gov.uk/docs/desh/publications/121107ppwedition5en.pdf

WESTERN AUSTRALIA (2009a) Guidance for the assessment, remediation and management of asbestos-contaminated sites in Western Australia, Environmental Health Directorate, Department of Health, Perth, Australia. Go to: http://tinyurl.com/oprnnzw

WESTERN AUSTRALIA (2009b) Management of small-scale low-risk soil asbestos contamination, Department of Health, Government of Western Australia, Perth, Australia. Go to: http://tinyurl.com/nghy4no

WATCH (2008), Insights from available animal toxicological data, Annex 6 of WATCH/2007/8, Working Group on Action to Control Chemicals. Go to: www.hse.gov.uk/aboutus/meetings/iacs/acts/watch/agendas.htm

WATCH (2011) Final WATCH position on asbestos risk assessment: February 2011, Working Group on Action to Control Chemicals. Go to: www.hse.gov.uk/aboutus/meetings/iacs/acts/watch/240211/agenda.htm

WHO (1997) Determination of airborne fibre concentrations. A recommended method, by phase-contrast optical microscopy (membrane filter method), World Health Organisation, Geneva (ISBN: 9-24154-496-1). Go to: www.who.int/occupational_health/publications/en/oehairbornefibre.pdf

WHO (2000) Air quality guidelines for Europe. Second edition, European series, No. 91, Regional Office for Europe, World Health Organization, Copenhagen, Denmark (ISBN: 9-28901-358-3). Go to: www.euro.who.int/__data/assets/pdf_file/0005/74732/E71922.pdf

WHO (2011) Guidelines for drinking-water quality. Fourth edition, Geneva, Switzerland (ISBN: 978-9-24154-815-1). Go to: http://whqlibdoc.who.int/publications/2011/9789241548151_eng.pdf

WRIGHT, K E and O’BRIEN, B H (2007) Fluidized bed asbestos sampler design and testing, INL/EXT-07-13122, Idaho National Laboratory, US Department of Energy National Laboratory, Idaho, USA. Go to: www.inl.gov/technicalpublications/Documents/3952792.pdf


CIRIA, C733164

StAtuteS

ActsCompensation Act 2006 (c. 29)

Part 2A of the Environmental Protection Act 1990 (c.43)

Environmental Protection Act (EPA) 1990 (c.43)

DirectivesDirective 2004/35/CE of the European Parliament and of the Council of 21 April 2004 on environmental liability with regard to the prevention and remedying of environmental damage (European Environmental Liability Directive)

Directive 2006/12/EC of the European Parliament and of the Council of 5 April 2006 on waste

Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008 on waste and repealing certain Directive (WFD)

RegulationsThe Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations (CDG) 2009 (No 1348)

The Construction (Design and Management) (CDM) Regulations 2007 (No. 320)

The Control of Asbestos Regulations (CAR) 2006 (No. 2739)

The Control of Asbestos Regulations (CAR) 2012 (No. 632)

The Environmental Damage (Prevention and Remediation) Regulations 2009 (No. 153)

The Environmental Damage (Prevention and Remediation) (Amendment) Regulations 2010 (No. 587)

European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) 2013

Registration, Evaluation, Authorisation & Restriction of Chemicals Regulations (REACH) 2008

The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (No. 3163)

Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), establishing a European Chemicals Agency, amending Directive 1999/45/EC and repealing Council Regulation (EEC) No 793/93 and Commission Regulation (EC) No 1488/94 as well as Council Directive 76/769/EEC and Commission Directives 91/155/EEC, 93/67/EEC, 93/105/EC and 2000/21/EC

Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006. Go to: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:353:0001:1355:EN:PDF

Standards

The NetherlandsNEN 5707:2003 Soil – investigation, sampling and analysis of asbestos in soil

NEN 2991:2005 Air – risk assessment n and around buildings or building construction which contain asbestos materials



BS ISO 13794:1999 Ambient air. Determination of asbestos fibres. Indirect-transfer transmission electron microscopy method

ISO 14966:2002 Ambient air. Determination of numerical concentration of inorganic fibrous particles. Scanning electron microscopy method

ISO/IEC 17025:2005 General requirements for the competence of testing and calibration laboratories

ISO/IEC 17020:2012 Conformity assessment. Requirements for the operation of various types of bodies performing inspection

BS ISO 10312:1995 Ambient air. Determination of asbestos fibres. Direct-transfer transmission electron microscopy method

UKBS 1377-1:1990 Methods of test for soils for civil engineering purposes. General requirements and sample preparation

BS 3882:2007 Specification for topsoil and requirements for use

BS EN 15051:2006 Workplace atmospheres. Measurement of the dustiness of bulk materials. Requirements and reference test methods

BS 10175:2011+A1:2013 Investigation of potentially contaminated sites – code of practice

USAASTM D5756-02 (2008) Standard test method for microvacuum sampling and indirect analysis of dust by transmission electron microscopy for asbestos mass surface loading. Go to: www.astm.org/Standards/D5756.htm

ASTM D5755-09 (2009) Standard test method for microvacuum sampling and indirect analysis of dust by transmission electron microscopy for asbestos structure number surface loading.Go to: www.astm.org/Standards/D5755.htm

ASTM D6480-05 (2010) Standard test method for wipe sampling of surfaces, indirect preparation, and analysis for asbestos structure number concentration by transmission electron microscopy.Go to: www.astm.org/Standards/D6480.htm

ASTM D7390-07 (2012) Standard guide for evaluating asbestos in dust on surfaces by comparison between two environments. Go to www.astm.org/Standards/D7390.htm


CIRIA, C733166

uSeful WebSIteS

HSEAsbestos: www.hse.gov.uk/asbestos/index.htm

Construction design and management (CDM): www.hse.gov.uk/construction/cdm.htm

Hidden killer: www.hse.gov.uk/ASBESTOS/hiddenkiller/index.htm

Packaging and documentation: www.hse.gov.uk/cdg/manual/commonproblems/asbestos.htm

RIDDOR: www.hse.gov.uk/riddor

VCA Packaging approvals database: www.dft.gov.uk/vca/dangerousgoods/packaging-approvals.asp

Other sourcesBritish and Irish Legal Information Institute: www.bailii.org.uk

The Association of Geotechnical and Geoenvironmental Specialists: www.ags.org.uk

Advanced Reach Tool (ART): www.advancedreachtool.com

British Occupational Hygiene Society: www.bohs.org

BAT reference documents: http://eippcb.jrc.es/reference

Chartered Institute of Environmental Health: www.cieh.org

Contaminated Land: Applications In Real Environments: www.claire.co.uk

Health Protection Agency (now Public Health England): www.hpa.org.uk

Health and Safety Executive: www.hse.gov.uk

Health and Safety Executive (training): www.hse.gov.uk/asbestos/training.htm

Health and Safety Laboratory: www.hsl.gov.uk

Institute of Occupational Medicine: www.iom-world.org

Land quality management: www.lqm.co.uk

Monitoring Certification Scheme: www.mcerts.org

Network for Industrially Contaminated Land in Europe (NICOLE): www.nicole.org

National Institute for Public Health and the Environment, the Netherlands: www.rivm.nl

Registered Ground Engineering Professional: www.ice.org.uk/topics/groundengineering/Registration-of-Ground-Engineering-Professionals

Specialist in Land Condition: www.silc.org.uk

Scotland and Northern Ireland Forum for Environmental Research: www.sniffer.org.uk

United Kingdom Accreditation Service: www.ukas.com

US EPA: http://epa.gov/superfund/health/contaminants/asbestos

Working Group on Action to Control Chemicals (WATCH) – a Government Scientific Advisory Committee and scientific and technical subcommittee of the HSC’s Advisory Committee on Toxic Substances (ACTS): www.hse.gov.uk/aboutus/meetings/iacs/acts/watch



A1 ACms in buildings listed in order ofeaseoffibrerelease(afterAppendix 2, hSe, 2010)


CIRIA, C733168

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els,

ca

lorifi

ers

etc.

All t

ypes

of a

sbes

tos

have

bee

n us

ed. C

roci

dolit

e us

ed

in la

ggin

g un

til 1

970.

Am

osite

was

pha

sed

out b

y th

e m

anuf

actu

rers

dur

ing

the

1970

s. C

onte

nt v

arie

s 6–

85%

. Va

rious

ad

hoc

mix

ture

s w

ere

hand

-app

lied

on jo

ints

an

d be

nds

and

pipe

runs

. Pre

-form

ed s

ectio

ns w

ere

wid

ely

used

, eg

‘85%

mag

nesi

a’ c

onta

ined

15%

am

osite

, ‘C

apos

il’ c

alci

um s

ilica

te s

labs

and

blo

cks

cont

aine

d 8–

30%

am

osite

whi

le ‘C

apos

ite’ s

ectio

ns c

onta

ined

~

85%

am

osite

. Bla

nket

s, fe

lts, p

aper

s, ta

pes

and

rope

s w

ere

usua

lly ~

100%

chr

ysot

ile.

The

ease

of fi

bre

rele

ase

ofte

n de

pend

s on

the

type

of

lagg

ing

used

and

the

surf

ace

trea

tmen

t. O

ften

it w

ill

be e

ncap

sula

ted

with

cal

ico

and

pain

ted

(eg

PVA,

EVA

, la

tex,

bitu

men

or p

ropr

ieta

ry p

olym

er e

mul

sion

s or

PVC

, ne

opre

ne s

olut

ions

), eg

‘Dec

adex

’ fini

sh is

a p

ropr

ieta

ry

poly

mer

em

ulsi

on. A

har

der c

hem

ical

-/w

eath

er-re

sist

ant

finis

h is

kno

wn

as ‘B

ulld

og’.

Asb

esto

s bo

ards

‘Mill

boar

d’‘M

illbo

ard’

was

use

d fo

r gen

eral

hea

t ins

ulat

ion

and

fire

prot

ectio

n. A

lso

used

for i

nsul

atio

n of

ele

ctric

al

equi

pmen

t and

pla

nt.

Croc

idol

ite w

as u

sed

in s

ome

mill

boar

d m

anuf

actu

re

betw

een

1896

and

196

5, u

sual

ly c

hrys

otile

. Mill

boar

ds

may

con

tain

37–

97%

asb

esto

s, w

ith a

mat

rix o

f cla

y an

d st

arch

.

Asbe

stos

‘mill

boar

d’ h

as a

hig

h as

best

os c

onte

nt a

nd

low

den

sity

so

is q

uite

eas

y to

bre

ak a

nd th

e su

rfac

e is

su

bjec

t to

abra

sion

and

wea

r.



Insu

latin

g bo

ard

Used

for fi

re p

rote

ctio

n, th

erm

al a

nd a

cous

tic in

sula

tion,

re

sist

ance

to m

oist

ure

mov

emen

t and

gen

eral

bui

ldin

g bo

ard.

Fou

nd in

ser

vice

duc

ts, fi

rebr

eaks

, infi

ll pa

nels

, pa

rtiti

ons

and

ceili

ngs

(incl

udin

g ce

iling

tile

s), r

oof

unde

rlay,

wal

l lin

ings

, sof

fits,

ext

erna

l can

opie

s an

d po

rch

linin

gs.

Croc

idol

ite u

sed

for s

ome

boar

ds u

p to

196

5, a

mos

ite

up to

198

0, w

hen

man

ufac

ture

cea

sed.

Usu

ally

15–

25%

am

osite

or a

mix

ture

of a

mos

ite a

nd c

hrys

otile

in c

alci

um

silic

ate.

Old

er b

oard

s an

d so

me

mar

ine

boar

ds c

onta

in u

p to

40%

asb

esto

s.

AIB

can

be re

adily

bro

ken,

giv

ing

sign

ifica

nt fi

bre

rele

ase.

Al

so s

igni

fican

t sur

face

rele

ase

is p

ossi

ble

by a

bras

ion,

bu

t sur

face

is u

sual

ly p

aint

ed o

r pla

ster

ed. S

awin

g an

d dr

illin

g w

ill a

lso

give

sig

nific

ant r

elea

ses.

‘Asb

esto

lux’,

‘T

urna

sbes

tos’

, ‘LD

R’, ‘

asbe

stos

wal

lboa

rd’,

‘insu

latio

n bo

ard’

. Mar

ine

boar

ds k

now

n as

‘Mar

inite

’ or ‘

Ship

boar

d’.

Insu

latin

g bo

ard

in c

ores

an

d lin

ings

of c

ompo

site

pr

oduc

ts

Foun

d in

fire

doo

rs, c

ladd

ing

infil

l pan

els,

dom

estic

boi

ler

casi

ngs,

par

titio

n an

d ce

iling

pan

els,

ove

n lin

ings

and

su

spen

ded

floor

sys

tem

s. U

sed

as th

erm

al in

sula

tion

and

som

etim

es a

s ac

oust

ic a

tten

uato

rs.

Croc

idol

ite u

sed

for s

ome

boar

ds u

p to

196

5, a

mos

ite u

p to

198

0, w

hen

man

ufac

ture

cea

sed.

16–

40%

am

osite

or

a m

ixtu

re o

f am

osite

and

chr

ysot

ile.

Can

be b

roke

n by

impa

ct. S

igni

fican

t sur

face

rele

ase

poss

ible

by

abra

sion

, but

usu

ally

pai

nted

or p

last

ered

. Sa

win

g an

d dr

illin

g w

ill a

lso

give

sig

nific

ant r

elea

ses.

‘Asb

esto

lux’.

Cap

osil.

Pape

r, fe

lt an

d ca

rdbo

ard

Used

for e

lect

rical

/hea

t ins

ulat

ion

of e

lect

rical

eq

uipm

ent.

Also

use

d in

som

e ai

r-con

ditio

ning

sys

tem

s as

insu

latio

n an

d ac

oust

ic li

ning

. Asb

esto

s pa

per h

as

also

bee

n us

ed to

rein

forc

e bi

tum

en a

nd o

ther

pro

duct

s an

d as

a fa

cing

/lin

ing

to fl

oorin

g pr

oduc

ts, c

ombu

stib

le

boar

ds, fl

ame-

resi

stan

t lam

inat

e. C

orru

gate

d ca

rdbo

ard

has

been

use

d fo

r duc

t and

pip

e in

sula

tion.

Asbe

stos

pap

er c

an c

onta

in ~

100%

chr

ysot

ile

asbe

stos

but

may

be

inco

rpor

ated

as

a lin

ing,

faci

ng

or re

info

rcem

ent f

or o

ther

pro

duct

s, e

g ro

ofing

felt

and

dam

p-pr

oof c

ours

es, s

teel

com

posi

te w

all c

ladd

ing

and

roofi

ng (s

ee b

elow

), vi

nyl fl

oorin

g. A

sbes

tos

pape

r is

also

so

met

imes

foun

d un

der M

MM

F in

sula

tion

on s

team

pi

pes.

Pape

r mat

eria

ls, i

f not

enc

apsu

late

d/co

mbi

ned

with

in

viny

l, bi

tum

en, o

r bon

ded

in s

ome

way

, can

eas

ily b

e da

mag

ed a

nd re

leas

e fib

res

whe

n su

bjec

t to

abra

sion

or

wea

r (eg

wor

n flo

orin

g su

rfac

e w

ith p

aper

bac

king

). As

best

os p

aper

, asb

esto

s fe

lt, ‘N

ovilo

n’ fl

oorin

g,

Dur

aste

el la

min

ates

, vin

yl a

sbes

tos

tile,

roofi

ng fe

lt an

d da

mp-

proo

f cou

rse

etc.

‘Pax

felt’

, ‘Vi

cero

y’ (f

oil-c

oate

d pa

per),

‘Ser

val’.

Text

iles

Rope

s an

d ya

rns

Used

as

lagg

ing

on p

ipes

(see

abo

ve),

join

ting

and

pack

ing

mat

eria

ls a

nd a

s he

at/fi

re-re

sist

ant b

oile

r, ov

en

and

flue

seal

ing.

Cau

lkin

g in

bric

kwor

k. P

laite

d as

best

os

tubi

ng in

ele

ctric

cab

le.

Croc

idol

ite a

nd c

hrys

otile

wer

e w

idel

y us

ed d

ue to

leng

th

and

flexi

bilit

y of

fibr

es. O

ther

type

s of

asb

esto

s ha

ve

occa

sion

ally

bee

n us

ed in

the

past

. Chr

ysot

ile a

lone

si

nce

at le

ast 1

970.

Asb

esto

s co

nten

t app

roac

hing

100

%

unle

ss c

ombi

ned

with

oth

er fi

bres

.

Wea

ving

redu

ces

fibre

rele

ase

from

pro

duct

s, b

ut

abra

ding

or c

uttin

g th

e m

ater

ials

will

rele

ase

fibre

s, li

kely

to

deg

rade

if e

xpos

ed, b

ecom

ing

mor

e fr

iabl

e w

ith a

ge. I

f us

ed w

ith c

aulk

ing,

fibr

es w

ill b

e en

caps

ulat

ed a

nd le

ss

likel

y to

be

rele

ased

.

Clot

h

Ther

mal

insu

latio

n an

d la

ggin

g (s

ee a

bove

), in

clud

ing

fire-

resi

stin

g bl

anke

ts, m

attr

esse

s, p

rote

ctiv

e cu

rtai

ns,

glov

es a

pron

s an

d ov

eral

ls. C

urta

ins,

glo

ves

etc

wer

e so

met

imes

alu

min

ised

to re

flect

hea

t.

All t

ypes

of a

sbes

tos

wer

e us

ed. S

ince

the

mid

-196

0s

the

vast

maj

ority

hav

e be

en c

hrys

otile

. Asb

esto

s co

nten

t ap

proa

chin

g 10

0%.

Fibr

es m

ay b

e re

leas

ed if

mat

eria

l is

abra

ded.

Gas

kets

and

was

hers

Used

wid

ely

in d

omes

tic a

nd in

dust

rial p

lant

and

pip

e sy

stem

s ra

ngin

g fr

om h

ot w

ater

boi

lers

to in

dust

rial

pow

er a

nd c

hem

ical

pla

nt.

Varia

ble

but u

sual

ly a

roun

d 90

% a

sbes

tos,

cro

cido

lite

used

for a

cid

resi

stan

ce a

nd c

hrys

otile

for c

hlor

-alk

ali.

Som

e ga

sket

mat

eria

ls c

ontin

ued

to b

e us

ed a

fter

as

best

os p

rohi

bitio

n in

199

9 (th

roug

h ex

empt

ion)

.

May

be

dry

and

dam

age

easi

ly w

hen

rem

oved

. Mai

nly

a pr

oble

m fo

r mai

nten

ance

wor

kers

. ‘Kl

inge

rit’,

‘Lio

n jo

intin

g’, ‘

Perm

anite

’, ‘C

AF’ –

com

pres

sed

asbe

stos

fibr

e or

‘It’

in G

erm

an g

aske

ts.

Strin

gsUs

ed fo

r sea

ling

hot w

ater

radi

ator

s.St

rings

hav

e as

best

os c

onte

nt a

ppro

achi

ng 1

00%

.


CIRIA, C733170

Fric

tion

prod

ucts

Resi

n-ba

sed

mat

eria

lsTr

ansp

ort,

mac

hine

ry a

nd li

fts,

use

d fo

r bra

kes

and

clut

ch

plat

es.

30–7

0% c

hrys

otile

asb

esto

s bo

und

in p

heno

lic re

sins

. Us

ed u

p to

Nov

embe

r 199

9.

Nor

mal

han

dlin

g w

ill p

rodu

ce lo

w e

mis

sion

s. M

inor

em

issi

ons

whe

n br

akin

g. D

ust m

ay b

uild

up

with

fric

tion

debr

is. G

rindi

ng b

rake

and

clu

tch

com

pone

nts

to fi

t and

br

ushi

ng o

r blo

win

g cl

ean

can

prod

uce

sign

ifica

nt p

eak

airb

orne

leve

ls.

Driv

e be

lts/c

onve

yor b

elts

Engi

nes,

con

veyo

rs.

Chry

sotil

e te

xtile

s en

caps

ulat

ed in

rubb

er.

Low

fria

bilit

y, ex

cept

whe

n w

orn

to e

xpos

e te

xtile

.

Cem

ent p

rodu

cts

Profi

led

shee

tsRo

ofing

, wal

l cla

ddin

g. P

erm

anen

t shu

tter

ing,

coo

ling

tow

er e

lem

ents

.

10–1

5% a

sbes

tos

(som

e fle

xibl

e sh

eets

con

tain

a

prop

ortio

n of

cel

lulo

se).

Croc

idol

ite (1

950–

1969

) an

d am

osite

(194

5–19

80) h

ave

been

use

d in

the

man

ufac

ture

of a

sbes

tos

cem

ent,

alth

ough

chr

ysot

ile

(use

d un

til N

ovem

ber 1

999)

is b

y fa

r the

mos

t com

mon

ty

pe fo

und.

Like

ly to

rele

ase

incr

easi

ng le

vels

of fi

bres

if a

brad

ed,

hand

saw

n or

wor

ked

on w

ith p

ower

tool

s. E

xpos

ed

surf

aces

and

aci

d co

nditi

ons

will

rem

ove

cem

ent m

atrix

an

d co

ncen

trat

e un

boun

d fib

res

on s

urfa

ce a

nd s

heet

la

ps. C

lean

ing

asbe

stos

-con

tain

ing

roof

s m

ay a

lso

rele

ase

fibre

s.

Asbe

stos

cem

ent,

Traf

ford

tile

, ‘Bi

gsix

’, ‘D

oubl

esix

’, ‘S

uper

six’,

‘Tw

in tw

elve

’, ‘C

ombi

ned

shee

t’, ‘G

len

six’,

‘3’

and

6’ c

orru

gate

d’, ‘

Fort

’, ‘M

onad

’, ‘T

roug

hsec

’, ‘M

ajor

tile

an

d Ca

nada

tile

’, ‘P

anel

she

et’,

‘Cav

ity d

ecki

ng’

Sem

i-com

pres

sed

flat s

heet

an

d pa

rtiti

on b

oard

Part

ition

ing

in fa

rm b

uild

ings

and

infil

l pan

els

for h

ousi

ng,

shut

terin

g in

indu

stria

l bui

ldin

gs, d

ecor

ativ

e pa

nels

for

faci

ngs,

bat

h pa

nels

, sof

fits,

lini

ngs

to w

alls

and

cei

lings

, po

rtab

le b

uild

ings

, pro

paga

tion

beds

in h

ortic

ultu

re,

dom

estic

str

uctu

ral u

ses,

fire

sur

roun

ds, c

ompo

site

pa

nels

for fi

re p

rote

ctio

n, w

eath

er b

oard

ing.

As fo

r pro

filed

she

ets.

Als

o 10

–25%

chr

ysot

ile a

nd

som

e am

osite

for a

sbes

tos

woo

d us

ed fo

r fire

doo

rs

etc.

Com

posi

te p

anel

s co

ntai

ned

~ 4%

chr

ysot

ile o

r cr

ocid

olite

.

Rele

ase

as fo

r pro

filed

she

ets.

Fla

t bui

ldin

g sh

eets

, pa

rtiti

on b

oard

, ‘Po

ilite

’.

Fully

com

pres

sed

flat s

heet

us

ed fo

r tile

s, s

late

s, b

oard

As a

bove

, but

whe

re s

tron

ger m

ater

ials

are

requ

ired,

and

as

sla

tes,

boa

rd c

ladd

ing,

dec

king

and

roof

sla

tes

(eg

rolle

r-ska

ting

rinks

, lab

orat

ory

wor

ktop

s). H

ighe

r asb

esto

s co

nten

t she

ets

prod

uced

for i

ndus

tria

l app

licat

ions

as

a hi

gh g

rade

arc

and

hea

t-res

ista

nt m

ater

ial.

As fo

r pro

filed

she

ets.

Up to

50%

chr

ysot

ile.

Rele

ase

as fo

r pro

filed

she

ets.

Asb

esto

s-co

ntai

ning

ro

ofing

sla

te (e

g ‘E

tern

it’, ‘

Turn

ers’

, ‘Sp

eake

rs’),

Eve

rite’

, ‘T

urna

ll’, ‘

Dia

mon

d AC

’, ‘JM

sla

te’,

‘Gla

sal A

C’, ‘

Emal

ie,

Eflex

’, ‘C

olou

rgla

ze’,

‘Thr

uton

e’, ‘

Wea

ther

all’.

‘Sin

dany

o’.

Pre-

form

ed m

ould

ed

prod

ucts

and

ext

rude

d pr

oduc

ts

Cabl

e tr

ough

s an

d co

ndui

ts. C

iste

rns

and

tank

s.

Dra

ins

and

sew

er p

ress

ure

pipe

s. F

enci

ng. F

lue

pipe

s.

Rain

wat

er g

oods

. Roo

fing

com

pone

nts

(fasc

ias,

sof

fits

etc)

. Ven

tilat

ors

and

duct

s. W

eath

er b

oard

ing.

Win

dow

si

lls a

nd b

oxes

, bat

h pa

nels

, dra

inin

g bo

ards

, ext

ract

ion

hood

s, c

opin

gs, p

rom

enad

e til

es e

tc.

As fo

r pro

filed

she

ets.

Rele

ase

as fo

r pro

filed

she

ets.

‘Eve

rite’

, ‘Tu

rnal

l’,

‘Pro

men

ade

tiles

’.



Oth

er e

ncap

sula

ted

mat

eria

ls

Text

ured

coa

tings

Dec

orat

ive/

flexi

ble

coat

ings

on

wal

ls a

nd c

eilin

gs.

3–5%

chr

ysot

ile a

sbes

tos.

Chry

sotil

e ad

ded

up to

198

4 bu

t old

sto

ck m

ay h

ave

been

us

ed fo

r sev

eral

mor

e ye

ars.

Non

-asb

esto

s ve

rsio

ns w

ere

avai

labl

e fr

om th

e m

id-1

970s

.

Gen

eral

ly fi

bres

are

wel

l con

tain

ed in

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.


CIRIA, C733172



A2 Case studies


CIRIA, C733174

CASe Study A2.1pARt 2A InSpeCtIOn Of A hOuSInG eStAte

Case study name Part 2A inspection of a housing estate

Consultant Land Quality Management Ltd

Country England

Source of asbestos Nearby former asbestos cement factory

type of asbestos Mainly chrysotile with smaller amounts of amosite (one analysis of ACM suggested 15 per cent chrysotile, 0.05 per cent amosite)

form of asbestosMainly broken asbestos cement sheets and other wastes (including slurry). But some evidence of highly degraded cement or “loose insulation material poss[ible] frag[ment] or lagging” or possible floor sweepings

Soil types Varied (including topsoil/made ground (gravely sand, sandy clay) overlying weathered chalk/sands and gravels

legal context Part 2A

Risk evaluation

As residents tend to spend more time inside rather than outside the home, and asbestos particles may be brought into the house on footwear and clothing or be blown in, residents’ greatest exposure is expected to be via inhalation of indoor dust. So, initial monitoring would involve sampling indoor air at selected properties. Monitoring would use optical microscopy techniques routinely used in the UK to certify when properties are ‘safe’ for reoccupation following asbestos removal works. However, it should be noted that as domestic air is expected to contain a high concentration of non-asbestos fibres, electron microscopy methods may also need to be employed. Monitoring would require air sampling at several appropriate locations within each property (in conjunction with ‘disturbance activities’ designed to replicate reasonable worst case conditions). In the absence of UK long-term environmental thresholds, the fibre counts from such monitoring would then be compared with the normal ‘clearance indicator threshold’ of less than 0.01 fibres/ml. This value was adopted as a decision support criteria (DSC) on the basis that the clearance indicator threshold, while “only a transient indicator of cleanliness … and not an acceptable permanent environmental level” (HSE, 2008b), logically should be less than the unacceptable level of exposure required by Part 2A.In addition to indoor air, residents, neighbours and the general public may be exposed to airborne asbestos in outdoor air. So, outdoor air monitoring should also be conducted. Such monitoring would also be assessed against the DSC. It is reassuring to note that asbestos levels when such monitoring was conducted in and around the estate did not exceed the DSC.Where all indoor air samples fall below the 0.01 fibres/ml threshold, no further action is warranted and it is unlikely that residents of the property could be considered at significant possibility of significant harm (SPOSH) from asbestos. If airborne asbestos concentrations exceed 0.01 fibres/ml and free fibres can be detected in garden soils, the Council should consider determining the property/area as contaminated land under Part 2A of the Environmental Protection Act 1990.



Risk evaluation

A draft investigation protocol was based on the clearance procedures used for enclosures during asbestos removal work but included ‘aggressive disturbance’ activities to simulate ‘reasonable worst case’ exposure of residents during cleaning, tidying or moving furniture etc. This draft procedure was tested at an unoccupied but furnished property, which indicated that the expected high levels of background dust generated by the aggressive disturbance were a challenge to usual optical microscopy analysis. Changes were made to the draft protocol to rectify this, including reducing the volume of air sampled and employing electron microscopy analysis.The final testing protocol was employed to measure the concentration of airborne asbestos fibres at four locations on the ground floor of 26 properties at the estate (~10 per cent of properties). No asbestos fibres were detected in the majority of these samples. However, a single amphibole fibre was detected in one sample at both Property 17 and Property 26, but the asbestos concentrations were still below the DSC. As a result, according to the pre-agreed DSC and associated procedures, no further action under Part 2A is warranted at 25 of the 26 properties tested.However, at one property (Property 15) one sample did exceed the DSC and contained a number of chrysotile asbestos fibres. This result was confirmed on additional samples taken at the same location but further sampling conducted without ‘aggressive disturbance’ indicated that the normal concentration of airborne fibres at the property was below the DSC. A number of actions were then taken:�� a survey was conducted, which identified a number of potential ACM within the property

that may have been a source for the fibres detected. However, the only materials shown to actually contain asbestos were floor tiles and adhesive, which it was deemed were highly unlikely to the source. Consequently, no internal source of asbestos could be identified for the fibres found in indoor air at the property

�� 10 soil samples were collected – five from the front gardens and five from the rear gardens. Testing of these samples identified small fragments of ‘lagging’ and asbestos cement in samples from the rear garden but no free asbestos fibres were identified. It is believed that free fibres would need to be present for asbestos to be transported into the property. As a result, the soil at the site did not appear to be the source of the fibres found in indoor air at the property

�� an ‘intensive environmental clean’ of the property was conducted by licensed contractors. No exceedance of the DSC was obtained when the property was re-tested with ‘aggressive disturbance’.

Reassurance and background monitoring of outside air, including that conducted as part of the stage 1 investigation, has repeatedly shown that the concentrations of airborne asbestos fibres at the estate are below the DSC.Under Part 2A of the EPA 1990, the Council does not have to demonstrate that the site is ‘safe’ or that no risk exists but rather to decide if the levels of asbestos contamination ‘in on or under the land’ represent SPOSH. As previously described, the results of the air monitoring at 25 of the properties do not indicate SPOSH. At Property 15, given that only a single sample within the initial sampling marginally exceeded the DSC and that monitoring without aggressive disturbance indicated that the DSC was not exceeded under normal conditions, it could be considered that residents at the property were unlikely to routinely encounter such airborne asbestos fibres. So, it is unlikely that SPOSH existed at the property even before the intensive environmental clean and certainly not afterwards.Based on the currently available evidence, LQM do not consider that a determination of the entire estate nor property 15 is justified under Part 2A. Assessment of additional properties at the estate does not appear to be justified under Part 2A as it is unlikely to result in an alternative conclusion. However, this conclusion should be reviewed as and when relevant authoritative UK guidance is published or if there are any changes to the legislation and guidance underpinning the DSC.The project did not considered other legislative regimes that may be relevant to the potential presence of asbestos in soils at a residential estate. It is understood that the Council continues to offer advice and support to residents relating to ACSs, including a free picking surface for any ACM exposed at the soil surface.


CIRIA, C733176

CASe Study A2.2fORmeR lARGe InduStRIAl SIte

Case study name Former large industrial site

Site –

Country Scotland

Source of asbestosAlthough a programme of safe asbestos removal had been undertaken before the demolition of site structures, fibres were later detected in several samples of made ground associated with earthworks in former process areas

type of asbestos Amosite, chrysotile and crocidolite

form of asbestos Fibres (not bulk ACMs) within made ground

Soil types Made ground, generally either gravelly fine to coarse sand or reworked glacial till and blaes, variably with cobbles and intermixed ash, brick, slag, metal, plastic and concrete

legal context

The site was being considered for redevelopment, so planning guidance (Scottish Executive, 2000) was applicable to ensure that the suitability of the site for its proposed use. A parallel assessment of the suitability of the site for its current use was also being undertaken, as parts of the site were not planned for redevelopment for several years.The management framework set out in Regulation 4 of CAR 2006 (now 2012) was also applied. This legislation, while originally designed to enforce the management of asbestos in buildings, is equally applicable to asbestos in soils.

Risk evaluation

Following the identification of asbestos fibres in several samples of made ground, it was acknowledged that there was no repeatable, scientific method of predicting the release of asbestos fibres from soils and the associated risks to human health.The US EPA’s (1997) Superfund approach was adopted, whereby in situations where asbestos is found to be present in soils under circumstances that may give rise to the release of asbestos fibres in air, the associated risks to human health are assessed through consideration of the nature, type and concentration of asbestos in soils in conjunction with activity based air monitoring.The activity based monitoring was undertaken in optimum (dry) weather conditions following US EPA (1997) guidance, which comprised continuous monitoring of air at set receptor points over two hour periods, during which time the surface soils over an area of ‘10 by 10’ were agitated using raking and a leaf blower.Three continuous air samples were taken during each monitoring event (one upwind, one downwind and one in the breathing zone of the analyst agitating the soils) and analysed for the presence of respirable fibres.All of the sample results were found to be lower than the limit of detection of the technique (<0.01 f/ml) and there was no statistically significant difference between the downwind, the upwind, or the personal exposure samples.The activity-based monitoring, in conjunction with soil testing and a robust CSM, was able to demonstrate that the fibres identified in made ground soils should not pose a significant risk to site users.Following consultation with regulators and peers, the findings of the asbestos risk assessment were incorporated into an asbestos management plan, in accordance with CAR 2012.

Remediation method

No immediate remediation was required, based on the risk evaluation. The safety of the future use of the area will be ensured though a remediation strategy linked with the site’s asbestos management plan.



CASe Study A2.3WOOlStOn RIveRSIde (fORmeR vOSpeR thORnyCROft ShIpyARd)

Case study name Woolston Riverside

Consultant Campbell Reith Hill LLP working for SEEDA (now HCA)

Site Former Vosper Thornycroft Shipyard, Victoria Road, Woolston

Country England

Source of asbestosMaterials from the site buildings and products associated with ship construction were used to raise levels on the southern part of the site. Normal investigations, using trial pits and boreholes, identified up to eight metres of made ground that incorporated ACM

type of asbestos Chrysotile was most frequently identified but crocidolite and amosite were also detected

form of asbestos The ACM included cement sheet, fibrous insulation, paper, gasket, plasticised products and cloth. Asbestos insulation board was also found occasionally

Soil types

The ACM was most apparent in gravel – cobble sized inclusions within the made ground, which occurred in lenses associated with the original tipping operation. However, later analysis also identified the presence of asbestos fibres in the sand-sized portion of the made ground. Cohesive made ground was not affected by ACM. The made ground was variable in nature from cohesive to granular. The made ground was underlain by river terrace deposits and alluvium, which were unaffected by ACM.

legal context

Works were completed in order to render the site ‘suitable for use’ under the planning PPS23 at that time (CLG, 2004 withdrawn). The works were also controlled by a wide range of other relevant regulation including in particular the Waste Management Regulations (and overseen by the HSE).

Risk evaluation

Initially the site wide investigation identified suspected ACM during trial pitting in the affected area.Supplementary works, under the supervision of a trained asbestos supervisor with full health and safety provisions and monitoring, were then completed using trial pits.A qualitative description of the types and forms of ACM and their distribution was then provided, which informed an initial qualitative appraisal of risk across the area affected.Detailed laboratory analysis of soil samples was then completed using a range of techniques to assess:�� the overall weight of asbestos in soils (gravimetric methods, which counted/weighed bulk

and soil asbestos fibre bundles)�� water suspension tests to count fibre numbers in solution (‘drop tests’)�� experimental dustiness release testing.

The results were assessed by the application of the Environment Agency survey algorithm [then in development by HSL] to rank areas and made ground material types for their hazard potential considering the form and type of asbestos and a risk factor associated with the type of asbestos. The water suspension tests were also used to consider fibre release potential. A hazard ranking was provided by this work and combined with GIS used to consider the areas that required treatment.The results of the dustiness release tests were evaluated using a modified (low-level extrapolation) Hodgson and Darnton (2000) risk assessment algorithm in order to express annual and lifetime risks from exposure to the ACSs. This informed the implications of any treated materials (which still contained some asbestos) being exposed on a temporary basis after the remediation.

Remediation method

A remediation trail was implemented to appraise the viability of soil screening and soil washing to remove ACM. This was completed in an existing building on site, which was approved by the HSE as a controlled enclosure. The results of this trail and the preceding evaluations were used to demonstrate the viability of the remediation strategy with respect to asbestos affected soils.The main remediation comprised the controlled treatment of the affected soils via soil screening/picking and the removal of the extracted bulk asbestos. The remainder of materials were placed in a pre-defined area of the site in an area proposed for a car park. The treated materials were placed under a 1.5 m engineered capping layer with a geotextile marker layer.


CIRIA, C733178

CASe Study A2.4hOuSInG develOpment

Case study name Feltham housing site

Site Feltham

Consultant Campbell Reith Hill LLP

Country England

Source of asbestosSuspected cement bound ACMs were identified at the formation level across the site following the start of ground works on a frequent basis. Asbestos cement was identified beneath the floor slab of some former structures and could also have arisen during demolition

type of asbestosThe ACM was typically in the form of cement in readily visible pieces. Asbestos was not determined to be present in a dispersed form of within the soils: this was confirmed by independent laboratory inspection

form of asbestos Mostly chrysotile containing cement sheet

Soil types Brown and grey silty sandy clay with gravel and brick, rubble, ash. In places clayey, sandy gravel

legal context

The development was planning led. Campbell Reith used IOM, an occupational asbestos specialist, to assist in the investigation, confirm visual descriptions of suspected ACM and advise on (and supervise on a full-time basis) health and safety matters for works. It was determined that the works could be completed under damp conditions with normal PPE due to the form of ACM present.

Risk evaluation

A forensic inspection was undertaken in an attempt to properly describe the nature of asbestos that had become apparent in the groundworks pre-enabling works. Close inspection was undertaken from trial pits on a 5 m to 10 m grid across the site.Stage 1 involved filling a 1 kg plastic sampling tub with the made ground arising from each trial pit based on random selection. The sample was then weighed and spread out across a polythene sheet and a detailed forensic inspection made for the presence of potential bulk ACM. Where these were identified, they were removed from the sample, collectively weighed and a correction factor applied based on the probable asbestos content for that type of material considering tables presented in HSEG 264 (HSE, 2005) (in this case a multiplier of 0.1 applied to the ACM weight as asbestos cement usually contains approximately 10 per cent asbestos). This allowed a simple calculation of asbestos weight in the soil sample.Stage 2 was competed as an additional exercise when suspected ACM were noted in the trial pit face and/or arisings. The stockpile of material from the trial pits was hand-picked for suspected ACM, and the dimensions of the trial pit recorded to calculate the overall volume. The handpicked material was weighed and an estimate of the amount of asbestos made (as above) and the overall weight of asbestos expressed in relation to the approximate weight of soil arisings, based upon a conversion factor.The reconstituted samples from Stage 1 and suspected ACM materials from Stage 2 were submitted for laboratory analysis for verification purposes. Analysis was also undertaken to determine the presence of asbestos fibres in soils, which would not necessarily be visible.The conclusion of work was that the level of suspected ACM was typically 0.01 per cent or less of the overall soils weight and in a readily identifiable and relatively stable form. This allowed a more pragmatic arrangement for health and safety provisions during the associated earthworks and a more cost effective landfill solution. This approach allowed a site wide inspection in a semi-quantitative manner, rather than sole reliance on sample analysis.

Remediation method Soils were removed to landfill under an Environmental Permit and appropriate health and safety controls



CASe Study A2.5fORmeR InduStRIAl SIte

Case study name Former industrial site

Site –

Country England

Source of asbestos –

type of asbestos Predominantly loose insulation, lagging-type material

form of asbestos Predominantly amosite with some chrysotile

Soil types –

legal context Part 2A

Risk evaluation

Approximately six soil samples per garden were collected (using a hand corer) from the surface 40 cm in the gardens of a large number of residential properties. Qualitative examination under PLM (HSE, 2005) was used to identify the presence of ACMs and/or free asbestos fibres. Where free fibres were detected, they were quantified by water suspension separation technique and fibre counting and fibre sizing. Amosite was identified in 36 per cent of samples and chrysotile in 11 per cent. Asbestos was mostly in friable forms (free fibres in 25 per cent and loose lagging in 15 per cent of samples) but some bound were also found ACM (cement in 2.6 per cent and AIB 0.8 per cent of samples).Outdoor air monitoring was conducted at seven locations over seven day period and filters analysed by SEM/EDXA for maximum sensitivity and fibre discrimination/identification. It was intended to monitor during dry and dusty weather in August and September, but rain was still encountered on eight of the 22 days of sampling. Most fibres identified were organic in nature. No asbestos fibres were detected in any samples and airborne concentrations were <0.00003 f/ml.Indoor monitoring was conducted at three properties with significant levels of asbestos in soils in order to assess ‘track back’ and potential indoor exposure. The properties were initially surveyed to identify any ACM within the fabric. Potential ACM was identified at all three properties but was not confirmed by sampling. Samples of deposited dust were then collected from carpets and surfaces using vacuum and swab sampling methods. Traces of amosite asbestos were detected in samples at all three properties, suggesting some degree of ‘track back’. However, indoor air monitoring conducted over a 24-hour period while residents continued normal activities demonstrated that normal airborne concentrations were low (<0.0002 fml) in all three properties.Personnel involved in soil sampling wore personal air monitoring equipment (~two hour samples). Sixteen filters from gardens with elevated asbestos concentrations were later analysed. Airborne asbestos was not detected when the soil was wet (ie winter) but airborne fibres were sometimes detected when sampling dry soils containing between 0.02 and 0.13 per cent asbestos. However, even these soils had been wetted before sampling for health and safety reasons. The concentrations in these 16 samples were below the LoQ (~0.005 f/ml). These levels are less than half those predicted in the subsequent exposure assessment.An exposure assessment (primarily relating to amosite) was conducted based on a number of assumptions:�� no exposure during wet weather�� indoor exposure is insignificant�� exposure is only likely during vigorous soil disturbance (digging/children playing) in dry

conditions. Such activities may generate dust concentrations of 100 μg/m3

�� such activities would be limited to ~90 hours/year and occur for a maximum of 15 years (ie 1350 hours)

�� only surface soils (<0.4 mbgl) are likely to be disturbed and release fibres�� release from dry soils would be similar to the data for amosite in clay reported by Addison et

al (1988).Based on these assumptions and using the HEI (1991) model, it was estimated that for a five year old child who became a smoker the combined excess lifetime cancer risk would exceed 1:100 000 (ie a minimal risk level) at amosite concentrations above 0.02 per cent. This value was used to define detailed criteria describing high, intermediate and low-risk properties based on asbestos in soil data.Properties rated as ‘hgh risk’ were recommended for determination under Part 2A and subsequent remediation.


CIRIA, C733180

CASe Study A2.6fORmeR bRICKWORKS

Case study name Former brickworks

Site –

Country –


type of asbestos –

form of asbestos –

Soil types –

legal context –

Risk evaluation

In 2004, a former brickworks was redeveloped as a small residential development. It was reported that full asbestos survey had been conducted and all ACM removed before demolition. Soil testing before construction did not identify any asbestos.In 2006 a resident raised concerns about the poor physical quality of soils within their garden, which resulted in the identification of asbestos cement fragments in the soil. Residents were advised to minimise soil disturbance until investigations were complete. Indoor and outdoor air monitoring was implemented and confirmed that there were no immediate health risks.A more detailed desktop study revealed that before 1960 the brickworks had used a steam cure process involving autoclave, boiler and steam engine. The potential asbestos contamination (surface and buried) relating to the decommissioning and disposal of this equipment had not been considered during the redevelopment.An intrusive investigation using a 10 m by 9 m-offset grid was undertaken under appropriate health and safety supervision to identify the extent of asbestos contamination within surface made ground (<1 mbgl).Representative samples of all fibrous materials were submitted for accredited analysis and identification. Where practical, a gravimetric assessment of a large sample (20 kg) was assessed on-site to quantify bulk asbestos content, but additional samples were collected for laboratory quantification of asbestos fibres. Made ground was typically gravelly silt or clay with variable proportions of brick and chalk and generally 0.5 m deep (max 1 m). ACM was found sporadically in the made ground, often immediately beneath the surface turf. ACM comprised predominately asbestos cement (chrysotile), but thermal insulation (chrysotile, amosite and crocidolite) was encountered. Fibrous materials exceeded 0.001 per cent at some locations (maximum 3.14 per cent). Laboratory testing identified occasional free fibres of chrysotile. The loose insulation materials and free fibres were considered to pose the greatest risks at the site, but air monitoring was considered essential to determine if significant exposures could be occurring.Air monitoring (personal and static sampling) was carried out before and during the excavation of trial pits as an indication of ‘worst case’ soil disturbance activities (ie digging and moving soils). Although countable fibres were detected, all air monitoring was below the relevant LoQ (<0.16-0.24 and <0.01 f/ml, respectively), but it should be noted that heavy rain was experienced during the works. Deposited dust samples were also collected within the properties.The HPA advised that an environmental level of 0.0005 f/ml had unofficially been adopted for other sites to assess adequate health protection. Air monitoring during the excavation works identified one to five airborne fibres (not necessarily asbestos fibres). The maximum fibre count could equate to an airborne fibre concentration of 0.0025 f/ml, which was considered a worst case theoretical level. A more reasonable average daily concentration was assumed to be 0.001 f/ml (assuming 12 hours/day in the garden but only six hours digging flower beds etc). This exceeds 0.0005 f/ml and was assumed to indicate a potentially unacceptable risk and so remedial measures were warranted.Costs for undertaking investigation works were approximately £30 000 and remedial activities believed at around £1m. Some of the costs were borne by the original investigation company.



CASe Study A2.7fORmeR lAndfIll

Case study name Former landfill

Site –

Country –


type of asbestos –

form of asbestos –

Soil types –

legal context –

Risk evaluation

The landfill operated from the early 1960s until 2005 and mainly received foundation excavation material and wastes from building maintenance. Due to a lack of records, the waste was investigated extensively in 2003, with the excavation of 28 trial pits. Analysis reported the presence of amosite in 143 of the 193 samples collected and chrysotile in 17. However, the form and condition of the ACMs was not apparent nor was the LoD of the analysis conducted.The waste mass was re-profiled over a one-month period in the summer of 2011, before capping and restoration. This involved excavating 27 700 m3 of asbestos-containing wastes using mechanical excavators and transporting it across parts of the site in trucks. During these works visible asbestos was removed and bagged - 70 standard asbestos bags were later disposed. Another 31.12 tonnes of potentially chemically-contaminated material was also disposed of as asbestos-contaminated waste.Because of the known presence of pervasive asbestos contamination, extensive precautions were taken during re-profiling. All workers used disposable coveralls over a change barrier. Appropriate masks were used, a high capacity water supply was available for dust suppression, and monitoring of asbestos in air was undertaken.Hourly meteorological data for the period suggests wind speed varied between 0.5 and 19 m/s (mean 5.4m/s), air temperatures were above 5.7°C throughout, humidity ranged between 54 and 98 per cent (mean 84 per cent) and rainfall was low (mean 1.8 mm per day).Reassurance monitoring was conducted immediately adjacent to the excavation and/or at the boundary of the landfill during works. Fibres were identified in all but one of the air samples collected, but the concentration was below the relevant LoQ (0.01 f/ml). This is also the contemporary control limit for asbestos. However, it should be noted that water sprays were reportedly being used during the collection of roughly 50 per cent of the samples. This would be expected to significantly reduce or prevent any fibre release.The fibre counts suggest that the average concentration of airborne fibre concentration surrounding the excavation could be 0.002 f/ml. Such levels are above background levels reported in urban environments in the 1980s (0.0001 f/ml).Personal monitors were also worn by workers at the excavation. Fibres were identified in all but one of the air samples collected, but the concentration was below the relevant Limit of Quantification (0.1 f/ml). This is also the contemporary ‘clearance indicator’ threshold. However, it should be noted that water sprays were reportedly being used during the collection of roughly 25% of the samples.


CIRIA, C733182

CASe Study A2.8ASbeStOS On RIGhtS Of WAy In SOuth CAmbRIdGeShIRe

Case study name Asbestos on rights of way in South Cambridgeshire

Consultant IOM Consulting Ltd

Site South Cambridgeshire, several rights of way

Country England

Source of asbestos Asbestos cement on tracks as infill

type of asbestos Chrysotile, amosite

form of asbestos Fibres in dust originating from crushed asbestos cement, pieces of asbestos cement

Soil types Track surface

legal context Relevant to Part 2A and Planning

Risk evaluation

Original assessment (Jones, 2005) indicated a measurable airborne fibre concentrations at track-side but low cumulative exposures, and so a low risk for nearby residents or for track users based on information on time spent on the track.An updated report commented on increased dust to be expected from increased traffic on one of the rights of way. The reassessed exposure suggested remediation was needed and we understand that has been required as a condition in a planning consent.

Remediation method Not known



A3 Review of Australian and new zealand policy

A number of documents relating to asbestos contamination in soils have been published by the enHealth Council or other authoritative bodies in Australia and New Zealand.

Imray and Langley (2001) describe and justify the derivation of health-based investigation levels (HILs) for a wide variety of soil contaminants. However, a HIL was not set for asbestos. Instead it was recommended that “appropriate site-specific measurements on a site are warranted if there are sufficient concerns based on site conditions and the nature of the asbestos”.

In 2003, Otness et al (2003) reported that although suitable analytical methods were not currently available, a criterion of <0.001 fibres/ml in air or <0.001 per cent in soil had been proposed to classify sites as ‘uncontaminated’ and ‘suitable for all land uses’, based on the work of Addison et al (1988). It also noted the lack of reliable and validated data on the relationship between soil and air levels and the fact that the epidemiological and exposure data are not sufficiently reliable to allow a dose response relationship to be identified for non-occupational situations. There is also a reported “inability or unwillingness to set acceptable ambient air levels of asbestos globally, except for occupational exposure” (Otness et al, 2003).

A report by enHealth (2005) acknowledges the need for risk assessment and management activities before redevelopment and the issues relating to the recycling of demolition arisings containing asbestos. Potentially affected sites included:

�� industrial land, eg asbestos cement manufacturing facilities, former power stations, rail yards and shipyards, especially large workshops and depots

�� discarded asbestos waste at old waste disposal sites or other locations, eg asbestos cement products, building waste and insulation material

�� asbestos waste from mining or manufacture of asbestos products used as infill

�� fire and storm damaged buildings

�� urban land with fill of unknown composition

�� sites where buildings or structures have been demolished or renovated, including residential land

�� disused services with asbestos concrete piping, eg water pipes, telecommunications trenches or pits, usually found within one metre of the surface.

It was stated that any soil guidelines should only be used “to enable classification of contaminated sites and to provide permission for development (not to determine health risk)” (enHealth, 2005).

A detailed desktop study is recommended that should include interviews with people with knowledge about the site and the source, type and amount of asbestos (eg building owners, occupiers or landowners), and an assessment of the age of existing or demolished buildings or structures at the site. This should be followed by a preliminary visual inspection of exposed areas of the site and, if necessary, samples taken to confirm the type of asbestos present. Random digging is preferred to systematic sampling because of the ‘likely variable distribution’. However, enHealth (2005) caution that expensive sampling and analysis plans that add little value to the risk assessment and management decisions should be avoided. A sample inspection checklist is provided in an appendix to their document.

However, enHealth (2005) did not specify an appropriate risk assessment process other than stating that a qualitative or quantitative assessment should be conducted, which considers issues such as:


CIRIA, C733184

�� the type, amount and condition/age of the asbestos

�� soil type (including moisture content) and surfacing (eg paved, grassed or exposed)

�� exposed surface area, depth and distribution

�� location and accessibility of the site

�� likely activities at the site.

enHealth (2005) also described a number of possible risk management options for ACSs, which are supported by case studies.

Guidance with a similar title has been published by New Zealand (Ministry of Health, 2007). This guidance is primarily aimed at regulators dealing with environmental health concerns relating to asbestos and does not specifically refer to asbestos in soil.

A3.1 GuIdelIneS On the ASSeSSment, RemedIAtIOn And mAnAGement Of ASbeStOS-COntAmInAted SIteS In WeSteRn AuStRAlIA

In 2009, the state of Western Australia produced guidelines on the assessment, remediation and management of ACSs (Western Australia, 2009a and 2009b). This comprehensive guidance takes a “risk-based and, where necessary, conservative approach to the uncertainties associated with protecting the public from asbestos-contaminated sites” but is designed to comply with the policy and legislation relevant to Western Australia. The assessment is based on classifying any asbestos in soil into three different types (see Table A3.1).

The guidance is based on the general principles described by enHealth (2005) but also adopts a number of additional policy-based decisions:

�� an investigation criterion or clean-up goal of 0.001 per cent asbestos in soil (w/w) for fibrous asbestos and free fibres

�� depending on site use, a criteria at least 10-fold higher can be used for bound ACMs in good condition (eg asbestos cement fragments)

�� for remediation purposes, the top 10 cm of soil should be free of visible asbestos or ACM

�� the asbestos air-quality limit for public protection around contaminated sites is 0.01 fibres/ml

�� the health risks from chrysotile and amphibole fibres are treated as being equivalent

�� the potential future release of free fibre from bound ACM should be considered

�� the excess lifetime cancer risk from asbestos should be kept “as low as practical and preferably no more than one in a million for the exposed population”.

A preliminary site investigation (PSI) should include a desktop review and a site walkover (potentially including preliminary sampling) to identify possible ACSs at the site. A detailed site investigation (DSI) is only needed where risk management measures require these areas to be better characterised and delineated, for example, a DSI may be needed when:

1 Remediation or management activities will involve the removal of soils.

2 Asbestos is present in the form of friable materials or free fibres.

3 The nature and extent of the asbestos will determine the future land use and site layout etc.

If a DSI is required it should involve a comprehensive sampling programme targeted at suspected areas of ACSs.

A tiered approach is also adopted to assessing the potential risks identified in the DSI:



�� Tier 1 screening risk assessment.

�� Tier 2 intermediate (simple) risk assessment.

�� Tier 3 detailed (site-specific) risk assessment.

Note that a simplified qualitative approach has also been developed for low-risk sites involving single properties affected by bonded asbestos as a result of on-site demolition or dumping (Department of Health, 2009b).

At Tier 1 asbestos concentrations are compared with generic soil asbestos criteria. The historical ad hoc use of the 0.001 per cent asbestos in soil criteria (Otness et al, 2003) were reviewed in light of the research conducted in the Netherlands (RIVM, 2003, and Swartjes and Tromp, 2008). Generic soil asbestos criteria for Western Australia have been derived by reducing the Dutch thresholds by one order of magnitude in order to account for the drier climate and treat chrysotile and amphibole asbestos equivalently. So, the Dutch limit for friable asbestos (0.01 per cent) becomes 0.001 per cent w/w for FA and AF, and the Dutch value of 0.1 per cent for non-friable asbestos is equivalent to 0.01 per cent for ACM in Western Australia. However, Western Australia also discriminates between different land uses based on assumed exposure ratios between them (see Table A3.2).

Note that the basis for the existing Dutch thresholds is currently under review, which may result in a significant reduction. Further details are discussed in Appendix A4.

Table A3.1 The three types of asbestos defined in Western Australia (Western Australia, 2009a)

type of asbestos Definition

Asbestos-containing material (ACM)�� asbestos is bound in a matrix (eg asbestos fencing or vinyl tiles)�� is in sound condition, although possibly broken or fragmented�� is restricted to material that cannot pass through a 7 mm × 7 mm sieve.

Fibrous asbestos (FA)

Friable asbestos, including:�� severely weathered ACM�� loose fibrous materials, such as insulation products�� can be broken or crumbled by hand pressure.

Asbestos fines (AF)�� free fibres of asbestos�� small fibre bundles�� ACM fragments that pass through a 7 mm × 7 mm sieve.

Table A3.2 Showing generic soil asbestos criteria adopted in Western Australia (Western Australia, 2009a)

Soil asbestos investigation criteria Asbestos type land use

0.001% w/w FA and AF (ie friable materials and free fibres) All land uses

0.01% w/w ACM (ie bound materials)Residential (including day care centres, preschool etc)

0.04% w/w ACM (ie bound materials) Residential with minimal soil access

0.02% w/w ACM (ie bound materials)Parks, public open spaces and playing field etc

0.05% w/w ACM (ie bound materials) Commercial and industrial

Following an appropriate investigation, if these limits are not exceeded no remedial action or management is required. However, where they are exceeded they can be used as clean-up goals, or site-specific assessment criteria can be developed by taking account of various mitigating factors (Tier 2 and 3). This may require a more detailed characterisation of the ACSs. Mitigating factors may include depth of contamination, form of contamination, binding or stabilising soil characteristics, likely activities at the site, or the nature of surface cover.


CIRIA, C733186

The guidance points out the difficulty in estimating the health risks associated with asbestos in soils and that quantitative assessments may not be possible. So, semi-quantitative and qualitative assessments may need to be used based on a reasonable worst case scenario. It is noted that the risk assessment may be an iterative process, as the emerging risks will drive, then be moderated by, the nature and effectiveness of management measures.

The document also described options for in situ management and treatment options, such as hand-picking and screening, and excavation with on or off-site disposal. Where remediation is required, an additional requirement is applied for the surface 10 cm to be completely free of visible asbestos, either by the placement of 10 cm of clean cover or hard surfacing. It is of note that Western Australia considers “that the health risks posed by an appropriately managed site, whereby the asbestos remains in situ subject to controls, are likely to be negligible and often preferable to removing the asbestos-containing materials from site”. It is also stressed that it is “important that the overall process be transparent, logical and reliable” and so the outcome of the risk assessment should be fully documented and explained, including a discussion of the uncertainties involved. Also, where the community has particular concerns, consideration should be given to managing perceived, as well as real, risks from asbestos.



A4 Review of netherlands policy

In comparison to the UK, the Netherlands has a history of publishing national guidance and assessment criteria for asbestos in soils (RIVM, 2003, and Swartjes and Tromp, 2008). This included an ad hoc intervention value in 1993, which was revised significantly when new values were published in 2000 (VROM, 2000). Then in 2002, an “interim policy on asbestos in soil, soil material and debris (granulate)” was published, which again suggested an alternative intervention value for asbestos in soils.

In 2003, RIVM produced a report for several Dutch government ministries (RIVM, 2003), which proposed a national framework for assessing risks from asbestos in soil. The tiered assessment process has subsequently been summarised and published in the scientific literature (Swartjes and Tromp, 2008). They describe new policy on soil contamination published by the Dutch government in 2006.

A4.1 dutCh pOlICy On ASbeStOS In AIRThe procedure proposed by RIVM (2003) and Swartjes and Tromp (2008) is based on Dutch policy on the assessment of risks from asbestos in air.

The Dutch Health Council considers that there is a difference in mesothelioma potency between chrysotile and amphibole (eg crocidolite and amosite) asbestos and between long (>5 µm) and short (<5 µm) fibres. Based on these assumptions they have stipulated a range of equivalence factors, which allow a single ‘fibre equivalents’ value to be calculated for any mixture of airborne asbestos fibres. These equivalence factors are:

�� 1 chrysotile fibre with a length > 5 µm: equivalence factor 1

�� 1 chrysotile fibre with a length < 5 µm: equivalence factor 0.1

�� 1 amphibole fibre with a length > 5 µm: equivalence factor 10

�� 1 amphibole fibre with a length < 5 µm: equivalence factor 1

Based on these equivalence factors, the Health Council of the Netherlands established a maximum permissible risk level (MPR) of 100 000 fibre equivalents per m3 of air (annual average) and a negligible risk level (NR) as one per cent of the MPR (ie an annual average of 1000 fibre equivalents per m3 of air).

Recently, however, a review of the epidemiological evidence conducted for the Health Council applied quality criteria and derived substantially different estimates for the relative potency of chrysotile and amphibole fibres (Burdorf and Heederik, 2011). Based on this work, the Health Council has recently proposed significant changes that would amend the equivalence factors and substantially reduce the existing MPR and NR levels. The proposed levels would also relate to measurements using TEM and consider both mesothelioma and lung cancer risks (see Table A4.1). For more information see Health Council of the Netherlands (2010).

Table A4.1 Comparison of the existing maximum permissible risk (MPR) and negligible risk (NR) levels for asbestos in air with revised levels proposed by the Health Council of the Netherlands. All values are expressed in fibres/m3 as measured using transmission electron microscopy (TEM)

existing values proposed new values

100% Chrysotile 100% Amphibole 100% Chrysotile Chrysotile with up to 20% amphibole 100% Amphibole

MPR 100 000 10 000 2800 1300 300

NR 1000 100 28 13 3


CIRIA, C733188

It is currently unclear how these proposed changes, if adopted, would affect the assessment of soils in the Netherlands. However, they could result in significant reductions to the intervention values and other criteria used in the tiered process described here.

A4.2 deRIvAtIOn Of A GeneRIC ASSeSSment CRIteRIOnIn the Netherlands, intervention values, which are derived using the Dutch national exposure model (CSOIL), are used as generic soil standards (Tier 0) to trigger remediation. However, the urgency of any remediation is determined based on a site-specific risk assessment where unacceptable risks are assumed unless there is evidence to the contrary (Swartjes and Tromp, 2008).

However, the CSOIL model was not considered appropriate for the assessment of ACSs because:

�� the model is based on fugacity theory and convective-diffusive transport, which are not applicable to asbestos fibres (Swartjes and Tromp, 2008)

�� the model does not consider factors such as soil moisture content and site activity patterns, which are essential in determining the risks from asbestos in soil (Swartjes and Tromp, 2008).

Instead, Intervention Values for ACSs were derived pragmatically, based on a database of over 1000 measurements of airborne fibre concentrations associated with ACSs resulting from either ‘worst case’ laboratory simulations or field experiments.

By comparing the airborne fibre equivalent concentrations with the existing NR and MPR levels, it was determined that at an Intervention Value of 100 mg/kg dw (for the sum of chrysotile and 10 times the amphibole asbestos) it was unlikely that the NR in air would be exceeded, even under worst case conditions. This value is applicable to both bound and friable asbestos but only “applied where no mechanical activities (digging, dumping or sifting etc) are expected to occur and the soil surface is likely to remain damp for most of the year (Swartjes and Tromp, 2008). RIVM (2003) concluded that, at this level, even if earthworks occur and the soil is dry, it is “unlikely that the MPR level in the air will be exceeded”. However, it was concluded that there was insufficient data to demonstrate the safety of raising the Intervention Value further.

Although the data suggested that bound asbestos would hardly ever result in airborne concentrations above the NR level, this is only considered during subsequent site-specific tiers of the risk assessment because it is too difficult to define when weathering and degradation of bound asbestos materials would result in friable materials (Swartjes and Tromp, 2008). However, RIVM (2003) had previously reported that, although rubble crushing of materials containing more than 10 000 mg/kg dw (asbestos equivalents) of bound asbestos produced elevated airborne fibre concentrations, a limit of 1000 mg/kg dw (asbestos equivalents) could safely be applied to ‘durable’ bound forms of asbestos.

The intervention value is also considered an appropriate residual concentration for recycled soils and granular demolition wastes in the Netherlands.

A4.3 tIeRed AppROACh tO ASbeStOS In SOIlA classic tiered approach to the assessment of ACSs has been proposed for use in the Netherlands and is summarised in Box A4.5 and Figure A4.1 (RIVM, 2003, and Swartjes and Tromp, 2008). The default assumption is that remediation is required unless the evidence to the contrary is demonstrated using the tiered framework. As with any tiered approach, conservatism is decreased but the complexity of the assessment increased at each successive tier: “simple when possible and complex when necessary” (Swartjes and Tromp, 2008).

noteDutch policy differs from that in the UK, and so these values are not directly applicable to the UK. However, no equivalent values have been set by the UK Government.



The approach requires all sampling and soil analysis to be compliant with NEN 5707:2003, which describes all aspects of the soil survey including sampling strategy, soil sampling protocol and laboratory analysis.

Box A4.5 Outline of the tiered assessment process adopted in the Netherlands (after RIVM, 2003, and Swartjes and Tromp, 2008)

RIVM (2003) had previously suggested that any hard-surfacing or paving (eg asphalt, concrete, tiles or clinker) should only be considered if it was 5 cm thick and that buildings should only be considered if they did not have ventilation spaces. An additional category of exclusion had also been proposed, namely “The land is not a sports ground, or track/road surfaced with asbestos-containing fill or if there are no buildings within 100 m”. However, these criteria were not listed in the later report of Swartjes and Tromp (2008).

Swartjes and Tromp (2008) state that “the decision on the degree of erosion is subjective. However, in a simple testing procedure in tier 1 a material is considered non-friable if it cannot be broken manually.”

Details of any changes required to this process, and the criteria used within it, in light of the recommendations of the Health Council to reduce the MPR and NR levels by over an order of magnitude, are awaited and may be significant.

Comparison with intervention value (tier 0):�� simple screen: compare the soil concentrations (mg/kg dw asbestos equivalents) with the intervention value

Simple qualitative testing (tier 1):�� requires no additional testing or analysis�� considers factors such as the form and condition of the asbestos (eg bound or friable), the intended land use and

site layout�� exposure regarded as impossible, or very unlikely, if:

�� asbestos is only present under buildings, paved areas or a water body (in sediment), on condition that no excavation or dredging activities are expected

�� asbestos is present at a soil depth of more than 0.5 m, on condition that no excavation activities are expected�� the site is permanently, year round, completely covered in vegetation�� for bound (non-friable) asbestos only: the average soil concentration does not exceed 1000 mg/kg dw (asbestos

equivalents), on condition that the bound materials are not seriously weathered or eroded.

Measurementofrespirablefibresinsoil(tier2):�� determine concentration of potentially respirable fibres (ie <3 µm diameter and <200 µm length) in the upper soil

layer in accordance with NEN 5707:2003 (involves a sedimentation procedure and SEM/EDXA analysis)�� where track back of soil/fibres to the indoor environment cannot be excluded, the amount of asbestos in household

dust must also be determined according to NEN 2991:2005�� risks can be considered highly unlikely if respirable fibre concentration is less than 10 mg/kg dw asbestos

equivalents (ie 4.3 E10 fibre equivalents/kg in soil or 100 fibre equivalents/cm2 in indoor dust)

Measurementofasbestosfibresinair(tier3):�� measurement of airborne asbestos fibres in outdoor air by:

�� field measurements under ‘standardised realistic worst case’ conditions�� laboratory simulation under ‘worst case’ conditions

�� measurement of airborne asbestos fibres in indoor air in houses or buildings no more than 100 m from the affected soil using NEN 2991 (only if appropriate and where friable asbestos is involved). However, a subsequent report (RIVM, 2004) showed that background house dust concentrations and background airborne fibre concentrations in the Netherlands may already exceed the proposed tiers 2 and 3 thresholds.�� testing should be conducted in rooms where fibres have been found in house dust and/or rooms with high

exposure potential�� measurements should be over six to eight hours duration and include simulated ‘daily practice activities’

�� fibre counts and analysis should be by SEM/EDXA analysis (ISO 14966:2002)�� risks can be considered negligible if the airborne fibre concentrations are below 1000 fibre equivalents/m3.


CIRIA, C733190

Figure A4.1 Dutch tiered site specific human health risk assessment framework for asbestos-containing soils (RIVM, 2003)

Tier 2:Respirablefibresdetermination

Tier3(indoors):Site-specificindoorairmeasurement

Tier 1:Simple assessment

Asbestos concentrations >100mg/kgdm(weighted)?

Asbestosunderroad-metallayer, buildings or 0 .5 m soil

No sports ground, no asbestos road and no buildings at

distance <100 m

Asbestos in wet sediment?

Bound asbestos concentration <1000mg/kgdm(weighted)?

Respirablefibresconcentration <10mg/kgdm(weighted)?

Asbestosfibreconcentrationinair<1000fibre

equivalents/m3(NRlevel)?

Contamination adjoins buildings, is regularly accessed and is also

located at ground level?

Sedimentedasbestosfibresassessment: is indoor air measurement necessary?

Asbestosfibreconcentrationinair<1000fibre

equivalents/m3(NRlevel)?

Site-specificriskspresent

Nosite-specificrisks

Tier3(outdoors):Site-specificoutdoorair measurement: site measurement(a)orlaboratorysimulation(b)

No

Yes

Yes

No

Yes

Yes

Yes

No

Site-specificrisksassessment(in3tiers):

No

No

Yes

No



A5 Review of uS epA policy

A significant amount of work has been conducted in the US, by both US EPA and at state-level, relating to the measurement and assessment of ACSs. In addition to the various guidance discussed here, there are a large number of documents relating to the investigation, assessment and remediation of the town of Libby, Montana, where the mining of vermiculite containing tremolite asbestos has resulted in wide-spread contamination of residential and non-residential areas of the town. Population screening suggested that Libby residents exhibited disproportionate pleural abnormalities and deaths by asbestos-related diseases (see US EPA, 2002).

Historically, US EPA use a one per cent asbestos rule in making decisions relating to the need for action relating to ACMs. In 2004, however, this rule was withdrawn because soils at Libby containing less than one per cent asbestos had been shown to release unacceptable airborne fibre concentrations. The rule was replaced by a requirement for site-specific sampling to quantify possible airborne fibre concentrations (Colorado Department of Public Health and Environment, 2007).

Subsequently, US EPA (2008) published a federal framework but no individual state has yet finalised guidance on the investigation and assessment of ACSs at state level, although various draft and discussion documents have been published.

In 2000, Pennsylvania Department of Environmental Protection published a report on asbestos in soil (PEP, 2000). This highlighted that different analytical techniques are required for asbestos compared to other contaminants. It also stated that standard algorithms for estimating dust inhalation from soil contamination may not be appropriate for asbestos and suggested that the regulation of ACSs should be based on airborne fibre concentrations.

The New Hampshire Department of Environmental Services published basic guidance for property owners covering the identification, remediation and management of asbestos wastes sites associated with historical asbestos manufacturing in the state (Varney et al, 2000).

In 2006, the state of Colorado published draft guidance, which was then updated in April 2007 (Colorado Department of Public Health and Environment, 2007). This is a comprehensive document that includes detailed descriptions of site survey and site investigation techniques appropriate for ACSs and consideration and precautions required during any remediation works. However, the document does not provide a detailed risk assessment framework for Colorado that can determine when remedial action is required. It should be noted many of the recommendations are driven by legislation specific to the US and the State of Colorado. To date this guidance does not appear to have been finalised.

In 2007, the Massachusetts Department of Environmental Protection released draft regulations and policy relating to asbestos in soil (MADEP, 2007). However the document is only a ‘draft for working group review’ and mainly describes changes to existing waste and soil reuse regulations with respect to asbestos in soil. It does not present any guidance on the assessment and management of such soils. As with the Colorado guidance, it is highly specific to US and state legislation. It is proposed that the waste classification and reuse of asbestos in soil will be based on the concentration of ‘asbestos source material’ (ASM) as determined using a sieving method, but it will not require measurements of asbestos fibres in soil. ASM is defined as friable ACMs with more than one per cent asbestos. The proposed regulations would apparently allow soils containing less than 150 mg ASM/kg to be reused, soils containing up to 1000 mg ASM/kg may be used as landfill daily or intermediate cover, soils containing up to 8000 mg ASM/kg may be used as pre-capping contouring materials (eg grading and shaping materials) at landfills and materials containing over 8000 mg ASM/kg should be disposed of as ‘special waste’. At the time of writing this guide, the proposed policy had yet to be adopted by MADEP.


CIRIA, C733192

At a federal level, the US EPA (2008) has published a framework US EPA, which recommends a tiered approach to the investigation and characterisation of health risks from ACSs. It is also supported by additional information and support via a dedicated website (see Useful websites). It should be noted that the framework is specific to asbestos and is limited in its remit by the wording and specific exclusions contained in Comprehensive Environmental Response, Compensation, and Liability Act 1980 (CERCLA). Such limitations may affect its direct applicability in the UK, where legislation has very different wording and remits.

According to the US EPA (2008), the framework is designed to address “the unique scientific and technical” challenges of asbestos in soil by providing flexible strategies “based on the best available science” and the use of common occupational hygiene methods for characterising asbestos exposure. It also acknowledges that the relationship between concentrations of asbestos in soil and levels of airborne asbestos fibres is complex and that there is currently no reliable method to predict one from the other. Consequently, the framework adopts empirical methods involving a combination of soil, dust and air monitoring. Also, on-site measurement of airborne fibre concentrations at distance from the soil source is recommended in preference to atmospheric dispersion models, which have not been validated for ACSs.

The recommended tiered framework, which is summarised in Figure A5.1, involves six tiers, or steps, that allow for assessment through to remedial/management actions at sites where asbestos is present in soils (excluding schools, building demolition and naturally-occurring asbestos). The framework is not prescriptive and allows the assessor to change focus from assessment of risks to design of appropriate remedial actions at any point. The document expresses a strong preference for the use of personal air monitors rather than static samplers, on the basis that these better estimate the actual exposure of the human receptors. It also recommends that all (or at least a subset) of samples are analysed using electron microscopy in order to obtain detailed information on the mineralogy of the fibres present.

Step 1 involves the review of current and historical information. Where asbestos can reasonably be expected to be present in soil, or if there is insufficient data, the assessment should proceed to step 2. Asbestos should be considered a potential contaminant at sites where one or more of the following sources may be present:

�� sites involved in the manufacture, transport or storage of ACMs and products, but also sites handling materials contaminated with asbestos (eg vermiculite from the Libby mine, Montana where remolite asbestos contamination from the mine is a significant issue in the USA)

�� sites with buildings built before 1970, which potentially contained ACM in their construction

�� sites authorised under the National Emissions Standards for Hazardous Air Pollutants (NESHAP) regulations, which included activities processing, handling and disposal of asbestos as well as demolishing or renovation of buildings containing ACM

�� sites affected by naturally occurring asbestos (NOA). In the USA, unlike the UK, significant areas are affected by NOA, particularly near to current and former asbestos mines etc.

Step 2 considers whether there is likely to have been (or there is a future threat of) a release of asbestos to the environment in which case the assessment should proceed to Step 3, unless the evidence supports immediate remedial intervention (Step 6). The framework suggests that at asbestos manufacturing sites etc the release of asbestos due to normal operations as well as disposal activities should be considered as potentially of concern unless strong evidence is present to the contrary.

Contemporary demolition of pre-1970s buildings in the US is covered by legislation that should preclude the release of asbestos (eg NESHAP). However, where such buildings were demolished, or destroyed (eg by fire) outside of these controls asbestos-containing debris may remain on-site. Such debris, even if it has been buried, should be considered as potentially of concern as it may be disturbed during redevelopment.

note‘Superfund’ refers to sites covered by CERCLA 1980. This legislation provides federal (rather than state) authority to identify and clean-up (sic) sites contaminated with hazardous substances.



Step 3 considers whether human exposure is likely taking account of the current and/or planned land use and the likely effects of weathering, migration and erosion on the asbestos materials involved. This involves evaluating if potential pathway(s) for human exposure exists at or near the site as part of a CSM. The pathways of concern are primarily outdoor inhalation of asbestos fibres from soil and indoor inhalation of asbestos fibres in dust. This assessment should include any reasonably anticipated changes in future and use, the current and future accessibility of the site and community awareness of the potential hazards. Such an assessment may also involve a review or collection of soil analysis data, but the inability of some testing methods (such as those based on PLM) to detect potentially hazardous level of asbestos in soils is highlighted. If pathways that may allow human exposure exist, the assessment should proceed to step 4 unless the evidence supports immediate remedial intervention (step 6).

Step 4 consists of preliminary environmental sampling to allow sites that are unlikely to pose significant risks under reasonable worst case conditions to be screened out using risk-based site-specific air action levels (AALs), which are derived using an appropriate epidemiological model.

US EPA (2008) recommends assessing potential outdoor exposure to fibres from soils using an appropriate activity-based sampling (ABS) method, which may include:

�� selection of a source area (~10 feet × 10 feet) that is likely to represent the highest levels of surface asbestos contamination at the site

�� operatives conducting vigorous disturbance activities, such as soil raking

�� personal monitoring equipment is used to estimate likely exposure to airborne asbestos fibres over a period of at least two hours

�� sampling conducted under reasonable worst case weather conditions (ie dry with light wind).

The type of disturbance activities employed should take account of the likely current and/or future activities at the site (if multiple exposure scenarios can be envisaged, multiple disturbance activities may need to be tested), likely variations in soil type, soil moisture and weather conditions etc.

Exposure to indoor dust can also be estimated by ABS using disturbance activities that are likely to maximise the re-suspension of settled dust. However, settled dust or wipe samples may also be used.

The exposure estimates obtained from ABS are then compared to AALs. If there is sufficient confidence that the AALs are unlikely to be exceeded (ie sampling adequately represents likely worst case exposures at the site), then no further assessment of asbestos risks should be required. However, if the AAL is exceeded in one or more ABS samples, the assessor may recommend further assessment (step 5) or the implementation of remedial measures (step 6) on a site-specific basis.

Step 5 is intended to provide a more detailed, site-specific and reliable estimate of the likely exposure at the site via indoor and/or outdoor inhalation. Such data will again involve ABS, but Step 5 sampling is likely to be more extensive and be more representative of actual site activities and the likely locations and exposure durations involved (US EPA, 2005). At this level of assessment, the exposure estimates obtained from the ABS would be used to estimate likely lung cancer and mesothelioma risks using an appropriate epidemiological model. If the level of risk predicted, together with a consideration of uncertainty, is below a site-specific risk management criteria no further action is needed. If the site-specific risk management criteria are exceeded, remedial measures (step 6) should be implemented.

Any remedial measures (or response actions) would be implemented in-line with CERCLA, which is specific to the US and not relevant to UK legislation and practice.

noteThe modelling approach described by US EPA (2008) is based on the concept of ‘inhalation unit risk’ for asbestos fibres. This is not an approach usually adopted in the UK for asbestos and care should be taken before applying it in a UK-context. Alternative models for asbestos risk are available and widely used in UK legal and occupational hygiene settings.


CIRIA, C733194

Figure A5.1 Flow diagram for investigating asbestos-contaminated superfund sites adopted by the US EPA (2008)

Step 1: Review historical and current data

�� does (did) the site use asbestos or materials contaminated with asbestos?�� do site buildings contain asbestos-containing material (ACM) or asbestos?�� does the asbestos contamination at the site fall outside the purview of other

authorities?�� is the site located within or near naturally-occurring asbestos (NOA) deposits?

Step2:Hastherebeen(oristhereathreatof)areleasetotheenvironmentdueto:

�� airborne release of fibres or disposal of asbestos-containing solid wastes?�� ACM-building debris remaining on site?�� disturbance of NOA by human activities?

Step 3: Is human exposure likely under current or future site conditions?

�� assess current activities at the site�� assess reasonable future land use activities at the site�� PLM source sampling

Step4:Preliminary(screeninglevel)environmentalsampling

�� conduct activity based sampling at a location with high source concentration and under conditions of high-end disturbance

Step5:Environmentalsampling:site-specificactivitybasedsampling(ABS)ofindoor and outdoor scenarios

�� develop and follow a QAPP�� conduct activity based sampling to determine air concentration to support

risk based site evaluation

Step 6: Response action and/or institutional controls

Risk management decison point 1 (see text)

Risk management decison point 2 (see text)

NFA

NFA

NFA

NFA

NFA

No

No

No

Yes

Yes

Yes

Revi

ew o

f site

con

ditio

ns s

uppo

rts

a re

spon

se a

ctio

n w

ithou

t add

ition

al in

vest

igat

ion

NFA = no further action


AECOM Ltd

Arcadis UK Ltd

Arup Group Ltd

Atkins Consultants Limited

Balfour Beatty Civil Engineering Ltd

BAM Nuttall Ltd

Black & Veatch Ltd

Bureau Veritas

Buro Happold Engineers Limited

BWB Consulting Ltd

Cardiff University

Environment Agency

Galliford Try plc

Gatwick Airport Ltd

Geotechnical Consulting Group

Golder Associates (Europe) Ltd

Halcrow Group Limited

Health & Safety Executive

Heathrow Airport Holdings Ltd (formerly BAA)

Highways Agency

Homes and Communities Agency

HR Wallingford Ltd

Institution of Civil Engineers

Lafarge Tarmac

London Underground Ltd

Loughborough University

Ministry of Justice

Morgan Sindall (Infrastructure) Plc

Mott MacDonald Group Ltd

MWH

Network Rail

Northumbrian Water Limited

Rail Safety and Standards Board

Royal HaskoningDHV

RSK Group Ltd

RWE Npower plc

Sellafield Ltd

Severn Trent Water

Sir Robert McAlpine Ltd

SKM Enviros Consulting Ltd

SLR Consulting Ltd

Temple Group Ltd

Thames Water Utilities Ltd

United Utilities Plc

University College London

University of Bradford

University of Reading

University of Salford

University of Southampton

WYG Group (Nottingham Office)

February 2014

Core and Associate members


The term ‘asbestos’ relates to several fibrous minerals regulated under UK law that areknown to cause serious health effects (including mesothelioma and lung cancer) wheninhaled. Asbestos-containing materials (ACMs) were widely used in construction, and thisguide identifies several key areas of uncertainty in current understanding, withrecommendations for future research and policymaking in order to address them.

Due to these uncertainties, the characterisation and assessment of potential risks is notstraightforward, and similar difficulties are being encountered in other developedcountries. This guide recommends a ‘lines of evidence’ approach whereby more than onemethod is used to estimate the airborne fibre concentrations likely to be generated fromsoils at the site.

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3Asbestos

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CIRIA9 780860 177371

Asbestos in soil and made ground:a guide to understanding

and managing risks


Asbestos in soil and made ground: a guide to understanding...

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