Landfill Guidelines - Towards Sustainable Waste Management In ...

Centre for Advanced EngineeringUniversity of Canterbury Christchurch New Zealand

LandfillGuidelines

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without the prior permission of the Centre for Advanced Engineering.

Landfill Guidelines

ISBN 0-908993-23-4

Printing History

First Published: April 2000

Copyright

© 2000 Centre for Advanced Engineering

PublisherCentre for Advanced EngineeringUniversity of CanterburyPrivate Bag 4800ChristchurchNew Zealand

Editorial Services, Graphics and Book Design

Charles Hendtlass, Centre for Advanced Engineering

Printing

Wickliffe Press, Christchurch

Cover Design

Hudson Design, Christchurch

Disclaimer

It will be noted that the authorship of this document has been attributed to the manyindividuals and organisations who have been involved in its production. While allsections have been subject to review and final editing, the opinions expressed remainthose of the authors responsible and do not necessarily reflect the views of the Centre forAdvanced Engineering. Although the authors have exercised due care in writing thisreport, no responsibility can be taken in its application by the authors, their employers,or the sponsoring organisations. Recommendations in the report need to be interpretedwith care and judgement.

This publication has been produced with financial support from the Sustainable Management Fund (SMF).

In addition to SMF funding, the project has been notable for the wide support it has received from local and regionalgovernment.

CAE is most grateful to the following organisations for their financial support of this project.

List of Project Sponsors

Sponsors• Dunedin City Council

• Environment BOP (Bay of Plenty Regional Council)

• Invercargill City Council

• Rotorua District Council

• South Taranaki District Council

• Taranaki Regional Council

• Wellington City Council

Joint Associate Sponsors• Canterbury Regional Council

• Horizons.mw (Manawatu-Wanganui Regional Council)

• New Plymouth City Council

• North Shore City Council

• Waitaki District Council

Associate Sponsors• Auckland City Council

• Buller District Coucil

• Central Hawkes Bay District Council

• Hauraki District Council

• Horowhenua District Council

• Matamata-Piako District Council

• Porirua City Council

• Southland Regional Council

Financial Supporter• Gisborne District Council

• Grey District Council

• Manawatu District Council

• Ruapehu District Council

• Timaru District Council

• Wanganui District Council

• Westland District Council

Acknowledgements

CAE, the Centre for Advanced Engineering, was es-tablished in May 1987, as a centre for the promotion ofinnovation and excellence in engineering and technol-ogy, to commemorate the centenary of the School ofEngineering at the University of Canterbury.

Vision Statement

To benefit New Zealand through promoting and en-couraging the application of advanced engineering andtechnology.

Objective

CAE aims to enhance engineering knowledge withinNew Zealand by technology transfer and the applica-tion of New Zealand and overseas research to engi-neering-related issues of national importance.

Key Activities

• CAE undertakes major projects that bring togetherselected groups of practising and research engi-neers and other experts from industry, researchorganisations, local and central government, terti-ary institutions, and the engineering profession.

• CAE also carries out smaller projects and organisesseminars, workshops and conferences as opportu-nities arise.

CAE projects aim to:

• Be of national importance with wide public appealand with tangible results.

• Facilitate technological co-operation amongst com-mercial and government organisations, tertiary in-stitutions and the engineering profession.

• Identify deficiencies in New Zealand’s technologi-cal capability and take action to promote the ad-dressing of these deficiencies.

• Undertake technology transfer rather than originalresearch.

Funding

CAE is an independent, non-profit organisation, fi-nanced mainly from the earnings of its trust fund. Thisfund, which currently stands at approximately $2.3million, consists of monies donated initially by 150corporate donors and 750 individual donors during the1987 Centennial Appeal, and more recently supple-mented by further donations during the 10th Anniver-sary Appeal. Other income is derived from sponsor-ship for specific projects, book sales and seminars. TheUniversity of Canterbury continues to make a majorcontribution to CAE by providing accommodation andfinancial services.

Administration

CAE is controlled by a Board of Directors comprisingrepresentatives from industry and commerce (includ-ing government and consulting engineers), the Univer-sity of Canterbury and other tertiary educational insti-tutions. The present Chairman is Dr Francis Small ofWellington. The Trust Fund is currently administeredby the University of Canterbury under the direction offour trustees. CAE has two executive staff and threeother staff engaged on publications and secretarialduties.

Executive Director John Blakeley has overall respon-sibility for CAE activities and Projects Director JohnLumsden co-ordinates CAE projects. From 1 May2000, Dr George Hooper succeeds John Blakeley asExecutive Director.

Principal Corporate Donors

Founders:

BHP New Zealand Steel Limited

Earthquake Commission

Electricity Corporation of New Zealand

Fisher & Paykel Industries Limited

Mainzeal Property and Construction Limited

McDonnell Dowell Constructors Limited

Opus International Consultants Limited

TransAlta New Zealand Limited

10th Anniversary Appeal:

Transpower New Zealand Limited

Contact:

CAE, University of Canterbury, Private Bag 4800

Christchurch, New Zealand

Street Address:

39 Creyke Road, Christchurch 8004

Telephone: +64-3-364-2478

Fax: +64-3-364-2069

e-mail: [email protected]

http://www.cae.canterbury.ac.nz

Executive Director: John P Blakeley(to April 30, 2000)

Dr George Hooper(from 1 May, 2000)

Projects Director: John L Lumsden

Publications Editor: Charles A Hendtlass

Centre for Advanced Engineering

Contributors

The following companies and individuals had input into the preparation of these Landfill Guidelines.

Task Group Leader

Laurence Dolan, Woodward-Clyde (NZ) Limited

Task Group Members

Tui Gilling, Ministry for the Environment

Peter Higgs, Perry Waste Services, Landfill Operators Group

Tony Kortegast, Tonkin and Taylor Limited

Mark Milke, University of Canterbury

Tom Wetherill, SCS-Wetherill Environmental, WasteMINZ

Consultants

Individual sections and sub-sections of this document were prepared by the following consultants and individuals:

Bell Gully (Ian Cowper)

Environment and Business Group (Conway Stewart, Susie Wood)

Peter Nelson

Pattle Delamore and Associates (Alan Pattle)

SCS-Wetherill Environmental (Murray Stirling, Tom Wetherill)

Taylor Baines and Associates (James Baines, Nick Taylor)

Tonkin and Taylor Limited (Arthur Amputch, Milind Khire, Tony Kortegast)

Woodward-Clyde (NZ) Limited (Laurence Dolan, Martin Evans, Ian Jenkins, Matthew Reed, Wayne Russell)

Reviewers

Mark Drury, Woodward-Clyde

Brian Gallagher, Timaru District Council

Jim Bradley, Ian Rowden, Montgomery Watson

Jenny Chetwynd, Carla Thorn, Ministry for the Environment

Contents • i

Contents

1 Introduction .............................................................................................................................. 11.1 Foreword ........................................................................................................................................ 1

1.2 Objectives and Aims ...................................................................................................................... 1

1.3 Waste Classification and Landfill Types ....................................................................................... 2

1.4 Layout of the Guidelines ................................................................................................................ 4

2 Landfills and Legislation ......................................................................................................... 52.1 Introduction .................................................................................................................................... 5

2.2 Resource Management Act (1991)................................................................................................. 5

2.3 Resource Consents ......................................................................................................................... 6

2.4 Resource Consent Application Process ......................................................................................... 11

3 Landfill Siting ........................................................................................................................... 133.1 Introduction ................................................................................................................................... 13

3.2 Landfill Siting Philosophy ............................................................................................................ 13

3.3 Strategic Planning ......................................................................................................................... 13

3.4 Site Selection Process ................................................................................................................... 14

3.5 Landfill Siting Criteria .................................................................................................................. 17

4 Landfill Design ......................................................................................................................... 234.1 Introduction ................................................................................................................................... 23

4.2 Design Philosophy ........................................................................................................................ 23

4.3 Design Considerations .................................................................................................................. 25

4.4 Groundwater Management and Control ........................................................................................ 30

4.5 Surface Water and Stormwater Management ............................................................................... 30

4.6 Leachate Generation and Characteristics ...................................................................................... 31

4.7 Leachate Retention and Liner Systems ......................................................................................... 35

4.8 Leachate Collection and Removal Systems .................................................................................. 38

4.9 Leachate Recirculation .................................................................................................................. 38

4.10 Leachate Treatment and Disposal ............................................................................................... 39

4.11 Landfill Gas Management ........................................................................................................... 40

4.12 Landfill Cover Systems ............................................................................................................... 43

4.13 Construction Quality Assurance and Construction Quality Control ........................................... 46

5 Landfill Operations ................................................................................................................. 515.1 Introduction ................................................................................................................................... 51

5.2 Landfill Management Plan ............................................................................................................ 51

5.3 Staffing and Training .................................................................................................................... 51

5.4 Health and Safety .......................................................................................................................... 52

5.5 Site Access .................................................................................................................................... 52

5.6 Waste Acceptance and Monitoring ............................................................................................... 52

5.7 Roading ......................................................................................................................................... 55

5.8 Visual Impacts ............................................................................................................................... 55

ii • Landfill Guidelines

5.9 Waste Compaction ........................................................................................................................ 55

5.10 Cover ........................................................................................................................................... 56

5.11 Nuisance Control ......................................................................................................................... 57

5.12 Fire Prevention ............................................................................................................................ 60

5.13 Water Control .............................................................................................................................. 60

5.14 Landfill Gas Management ........................................................................................................... 62

5.15 Closure and After-care ................................................................................................................ 63

6 Landfill Monitoring ................................................................................................................. 656.1 Introduction ................................................................................................................................... 65

6.2 Objectives of Monitoring .............................................................................................................. 65

6.3 Leachate Monitoring ..................................................................................................................... 65

6.4 Groundwater Monitoring .............................................................................................................. 66

6.5 Surface Water Monitoring............................................................................................................. 73

6.6 Analysis and Review of Monitoring Data ..................................................................................... 77

6.7 Landfill Gas Monitoring ............................................................................................................... 79

Glossary ........................................................................................................................................ 85

Bibliography................................................................................................................................. 89

Appendices ................................................................................................................................... 91Appendix 1: Relevant Case Law ......................................................................................................... 91

Appendix 2: Relevant Regulatory and Best Practice Background...................................................... 93

Appendix 3: Landfill Management Plan Outline Table of Contents .................................................. 99

Appendix 4: Waste Classification for Landfill Disposal ................................................................... 101

Appendix 5: USEPA Toxicity Characteristic Leaching Procedure Limits ........................................ 105

Appendix 6: NSWEPA Leachable Concentrations and Total Concentration Values for Solid Waste Landfills .............................................................................................. 107

Index ............................................................................................................................................ 109

FiguresFigure 1.1: Environmental protection — illustrations of source/receptor/pathway ............................. 2

Figure 4.1: Typical operational plan for landfill site .......................................................................... 29

Figure 4.2: Landfill water balance issues ............................................................................................ 34

Figure 4.3: Recommended liner designs ............................................................................................. 36

Figure 4.4: Example of passive landfill gas venting well ................................................................... 42

Figure 4.5: Example of passive landfill gas venting system ............................................................... 43

Figure 4.6: Example of landfill gas extraction well ............................................................................ 44

Figure 4.7: Examples of final cover designs ....................................................................................... 45

TablesTable 2.1: Regulatory authority resource consent responsibilities ...................................................... 9

Table 4.1: Changes in leachate composition in different stages of a landfill ..................................... 32

Table 4.2: Leachate characteristics at selected New Zealand landfills ............................................... 33

Contents • iii

Table 4.3: Typical constituents found in landfill gas .......................................................................... 41

Table 4.4: Soils - recommended tests and testing frequencies for material qualification before construction........................................................................................ 46

Table 4.5: Soils - recommended tests and testing frequencies prior to installation ............................ 47

Table 4.6: Soils - recommended tests and testing frequencies during construction ........................... 47

Table 4.7: Geotextile - recommended tests and testing frequencies ................................................... 48

Table 4.8: Geomembrane - recommended tests and testing frequencies ............................................ 48

Table 4.9: Geosynthetic clay liner - recommended tests and testing frequencies .............................. 49

Table 4.10: Geocomposite - recommended tests and testing frequencies .......................................... 49

Table 6.1: Example leachate monitoring programme for a regional landfill ...................................... 67

Table 6.2: Example groundwater monitoring programme for a regional landfill ............................... 71

Table 6.3: Example surface water monitoring programme for a regional landfill .............................. 75

Table 6.4: Example surface water monitoring strategy ...................................................................... 77

iv • Landfill Guidelines

Introduction • 1

Chapter 1Introduction

1.1 ForewordThese Landfill Guidelines are a revision of the CAELandfill Engineering Guidelines, originally publishedin “Our Waste: Our Responsibility” (1992).

Landfill siting, design, operations and monitoring haveundergone major advances over the last thirty years.Awareness of the issues related to managing variouscategories of waste, together with growing concernsover the environmental effects of waste disposal, haveseen significant improvement in the siting, design,operation and monitoring of waste disposal facilities incountries where waste disposal practices are not dic-tated entirely by cost.

However, current practice remains variable through-out New Zealand.

These revised guidelines have been written to:

• reinforce key components of the 1992 LandfillEngineering Guidelines;

• outline key issues and requirements with respect tothe applicable legislation;

• provide additional guidance on siting, design andconstruction, with respect to new landfills andlateral expansions of existing landfills; and

• provide additional guidance on operations andmonitoring at all operating landfills.

1.2 Objectives and AimsThe objectives of these Landfill Guidelines are to:

• provide the basis for siting, design, development,operation and monitoring of landfills in New Zea-land in an environmentally acceptable and sustain-able manner;

• provide practical guidance to landfill owners, op-erators and regulatory authorities in meeting theirrequirement to avoid, remedy or mitigate the ad-verse effects of landfill disposal, in accordancewith the Resource Management Act (1991);

• reflect current recommended waste industry prac-tice (both private and local authority) for key as-

pects of siting, design, operation and monitoring ofmunicipal solid waste landfills, both new and ex-tensions of existing sites, in the light of:

— developments in the practice of landfill siting,design, operation and monitoring;

— experience in the use and implementation of the1992 Landfill Engineering Guidelines by landfilloperators and regulatory authorities; and

— experience in the implementation of the Re-source Management Act (1991).

In achieving these objectives these guidelines aim to:

• outline the key considerations in the siting, designoperation and monitoring of landfills on a site-specific basis; and

• provide a consistent approach to landfill design andmanagement to reduce the actual and potentialeffects of landfills on the environment.

These guidelines deal specifically with municipal solidwaste landfills intended to accept municipal solidwaste, as defined in Section 1.3 below.

Within New Zealand there are no specific and legally-binding requirements for the siting, design, operationand monitoring of landfills.

The final decision on site-specific requirements ismade by the appropriate regulatory authority, or theEnvironment Court, under the provisions of the Re-source Management Act (1991), following a site-spe-cific assessment of effects on the environment.

Siting, designing and operating landfills, after consid-eration of the issues and, in accordance with recom-mendations contained in these guidelines, is expectedto provide a reasonable assurance that the landfill sitewill not have significant adverse effects on the envi-ronment.

In developing and evaluating landfill proposals, landfillowners, operators and regulatory authorities need toconsider in detail the resulting actual and potentialeffects on the environment taking into account thefollowing:

• landfill size;

2 • Landfill Guidelines

• landfill location and site characteristics;

• surrounding environment; and

• local community.

Specifics of siting, design, operations and monitoringwill be determined following detailed technical, andnon-technical, investigation and analysis.

Therefore, these guidelines do not eliminate the neces-sity for the development of site-specific requirementsfor investigations, design, operations and monitoring.

Figure 1.1 indicates the general issues associated withlandfills and protection of the surrounding environ-ment.

These guidelines are not intended to be a detailedtechnical manual, but rather a basis for landfill opera-tors and regulatory authorities to seek detailed techni-cal, planning and legal advice from appropriately quali-fied and experienced individuals and companies.

1.3 Waste Classification andLandfill TypesIn this document waste classification and landfill typesare defined as follows.

Waste ClassificationWaste is classified into four general categories:

• cleanfill material (or inert waste);

• municipal solid waste;

• industrial waste; and

• hazardous waste.

Cleanfill Material (or Inert Waste)

Cleanfill material, or inert waste, is waste that does notundergo environmentally-significant physical, chemi-cal, or biological transformations, and has no poten-tially hazardous content once landfilled. It must not becontaminated or mixed with any other material.

Cleanfill material is defined as:

• Material that when discharged to the environmentwill not pose a risk to people or the environment,and includes natural materials, such as clay, soiland rock, and other materials, such as concrete,brick or demolition products, that are free of:

— combustible, putrescible, degradable orleachable components;

— hazardous substances or materials (such as

Gases and odours

Evaporation

WASTE

Infiltration

Noise, dust, litterand visual effects

Contaminatedsurface water

runoff

DitchRiver

PeopleHousing

Supplyborehole

Woodland

CLAY

SAND

Saturated zone

Unsaturated zone

Methane migration infissures or permeable zones

Seepage of leachate

Leachate level within site

Groundwater

Precipitation

Prevailing wind direction

Figure 1.1: Environmental protection — Illustrations of source/receptor/pathway

(Modified Figure 3.4 from UK Department of the Environment Waste Management Paper No. 26 B (1995))

Introduction • 3

municipal solid waste) likely to create leachateby means of biological breakdown;

— any products or materials derived from hazard-ous waste treatment, stabilisation or disposalpractices;

— materials such as medical and veterinary waste,asbestos, or radioactive substances that maypresent a risk to human health if excavated; and

— contaminated soil and other contaminated ma-terials.

Municipal Solid Waste

Municipal solid waste is any non-hazardous, solidwaste from a combination of domestic, commercialand industrial sources. It includes putrescible waste,garden waste, uncontaminated biosolids and clinicaland related waste (including contaminated waste steri-lised to a standard acceptable to the Department ofHealth). All municipal solid waste should have anangle of repose of greater than five degrees (5˚) andhave no free liquids.

It is recognised that municipal solid waste is likely tocontain a small proportion of hazardous waste fromhouseholds and small commercial premises that stand-ard waste screening procedures will not detect. How-ever this quantity should not generally exceed 200 ml/tonne or 200 g/tonne.

Industrial Waste

Industrial waste is that waste specific to a particularindustry or industrial process. It may contain some-what higher levels of contaminants, such as heavymetals and human-made chemicals, than municipalsolid waste and needs to be managed with environmen-tal controls appropriate to the specific waste(s) beinglandfilled.

Hazardous Waste

Hazardous waste is waste that poses a present or futurethreat to people or the environment as a result of one ormore of the following characteristics:

• explosiveness;

• flammability;

• capacity to oxidise;

• corrosiveness;

• toxicity; and/or

• eco-toxicity.

Hazardous waste contains contaminants such as heavymetals and human-made chemicals, at levels highenough to require treatment to render them safe beforelandfill disposal.

For further discussion on hazardous waste refer to theCAE document Management of Hazardous Waste(2000). For recommendations on landfill waste ac-ceptance criteria with respect to hazardous waste, referto Section 5.6 of these guidelines.

Landfill TypesLandfills are classified into four categories:

• cleanfill;

• municipal solid waste landfill;

• industrial waste landfill; and

• hazardous waste landfill or hazardous waste con-tainment facility.

Cleanfill

A cleanfill, or inert waste landfill, is any landfill thataccepts only cleanfill material and inert wastes, includ-ing clean excavated natural materials. In general theonly effective environmental controls on discharges toland and water from cleanfills relate to waste accept-ance criteria.

Municipal Solid Waste Landfill (MSWL)

A municipal solid waste landfill (MSWL), also oftenreferred to as a sanitary landfill, is any landfill thataccepts municipal solid waste. A municipal solid wastelandfill may also receive inert waste.

Industrial Waste Landfill (IWL)

An industrial waste landfill (IWL) is a landfill that isdesigned to accept predominantly industrial waste. Inmany cases industrial waste landfills are monofills,associated with a specific industry or industrial loca-tion (for example mining, forestry and smelting) anddesigned and operated in accordance with the specificwastes targeted. Design, operation and monitoringrequirements may be more, or less, stringent than formunicipal solid waste landfills. An industrial wastelandfill may also receive municipal solid waste andinert waste, depending on design.

Hazardous Waste Landfill (HWL)

A hazardous waste landfill (HWL), or hazardous wastecontainment facility (HWCF) is any landfill that ac-cepts waste formally defined as “hazardous waste” instatutory instruments, or as specifically determined


through any special requirements that may be set by theEnvironmental Risk Management Authority (ERMA).

Siting, design, operations and monitoring requirementsfor landfills accepting hazardous waste will be consid-erably more stringent than for landfills accepting onlymunicipal solid wastes.

For further discussion on hazardous waste landfillsrefer to the CAE document Management of HazardousWaste (2000).

1.4 Layout of the GuidelinesThese Guidelines are set out in the following sections:

• landfills and legislation;

• siting;

• design;

• operations; and

• monitoring.

Landfills and Legislation • 5

Chapter 2Landfills and Legislation

2.1 IntroductionThis section provides a description of the legislativerequirements with respect to landfills. It addresses therequirements in the Resource Management Act (1991)(the Act), including the following:

• requirements for designations and resource con-sents; and

• the resource consent application process.

Relevant case law is provided in Appendix 1.

2.2 Resource ManagementAct (1991)

Purpose and PrinciplesOn 1 October 1991 the Resource Management Act(1991) became the legislation controlling resource usein New Zealand. Part II of the Act sets out the purposeand principles. The purpose of the Act is:

“To promote the sustainable manage-ment of natural and physical resources”.

The Act provides a definition of “sustainable manage-ment”. Essentially, the term means communities man-aging resources to provide for their social, economic,and cultural well-being and for their health and safetywhile meeting certain environmental imperatives. Thepotential of natural and physical resources to meet thereasonably foreseeable needs of future generationsmust be sustained, the life-supporting capacity of re-sources must be safeguarded and adverse effects ofactivities on the environment must be avoided, rem-edied or mitigated. This last focus upon the effects ofactivities is a key feature of the regime introduced bythe Act.

The Act also sets out a number of matters of nationalimportance (including the preservation of the coastalenvironment, wetlands, lakes and rivers, the protectionof outstanding natural features, landscapes and signifi-cant indigenous vegetation). Other matters to whichdecision-makers must have regard include the intrinsicvalue of ecosystems and the maintenance and enhance-ment of amenity values.

The Act introduces specific emphasis on the interestsand resource management concerns of Maori.

Jurisdiction of Local GovernmentLocal government functions are divided between re-gional councils and territorial authorities (district andcity councils). Sections 30 and 31 of the ResourceManagement Act (1991) set out in detail the differentfunctions of regional councils and territorial authori-ties.

Regional CouncilsUnder section 30 of the Act, the functions of regionalcouncils include:

• the preparation, implementation and review of ob-jectives, policies and methods to achieve integratedmanagement of natural and physical resources ofthe region;

• the preparation and implementation of policies inrelation to the actual or potential effects of the use,development or protection of land, which are ofregional significance;

• the control of the use of water and land for soilconservation;

• the control of the discharge of contaminants;

• avoidance of natural hazards;

• maintenance of water quality;

• the prevention of adverse effects of hazardoussubstances; and

• activities in, or affecting, the coastal marine area.

Issues, objectives, policies and rules in relation to theseresource management functions within a region arecontained within its regional policy statement andregional plans.

A regional council is responsible for assessing re-source consent applications for activities where itspolicy statement or a regional plan requires this. Thesecan be any of the following:

• a discharge permit;


• a water permit;

• a land use consent; or

• a coastal permit.

Territorial Authorities (District and CityCouncils)The functions of territorial authorities include:

• preparation of district plans, which state the re-source management issues, objectives, policies andmethods to be used and environmental results en-visaged for the district;

• control of the actual or potential effects of activitieson land and on the surface of water in lakes andrivers;

• the prevention or mitigation of the actual or poten-tial effects of natural hazards and storage, use,disposal, or transportation of hazardous substances;

• the control of the subdivision of land; and

• control of noise.

2.3 Resource ConsentsThere are five different types of resource consent.These are:

• discharge permit;

• water permit;

• land use consent;

• coastal permit; and

• subdivision consent.

A description of those consents that are particularlyrelevant to refuse landfills is set out below.

Discharge PermitsUnder the Act, a landfill falls within the definition of“industrial or trade premises” as:

“Any premises used for the storage,transfer, treatment, or disposal of wastematerials or for other waste manage-ment purposes, or used for compostingorganic materials”.

Accordingly, under section 15 of the Act, no personmay discharge any contaminant to air, water or landassociated with the landfill unless expressly allowedby a rule in a regional plan or proposed regional plan,

a resource consent, or a regulation. Regional councilsare responsible for assessing applications for resourceconsents (discharge permits) relating to discharges toland, air and water.

Discharge to Land

Landfills require a discharge permit for any dischargeof water or contaminants directly onto land unlessexpressly provided for in a regional plan, proposedregional plan, resource consent or regulation.

A single generic discharge permit is usually used tocover all discharges of solid waste to land at thelandfill.

Discharge permits for the discharge of solid waste toland generally contain conditions relating to:

• location of solid waste discharges;

• quantity of solid waste to be discharged;

• waste acceptance criteria;

• liner and leachate collection systems;

• cover systems;

• acceptance of designs;

• peer review (in some circumstance); and

• bond or financial assurance (in some circumstances).

Discharge to Water

Landfills require a discharge permit for any dischargeof water and/or contaminants directly into water (sec-tion 15(1)(a)), or onto land in circumstances where itmay result in a contaminant entering water (section15(1)(b)), unless provided for in a plan, proposed plan,resource consent or regulation.

Activities that require a discharge permit under section15(1)(a) include discharges of clean and/or contami-nated surface stormwater and groundwater from agroundwater control system. In some cases a singleconsent may be used for all surface water, orgroundwater discharges, within a single defined catch-ment. In others, a separate permit may be required foreach separate discharge.

The disposal of collected uncontaminated water mayrequire a discharge permit if this is directly to water.

Discharge permits for discharges of contaminants, orwater, to water at landfills generally contain conditionsrelating to:

• location of discharges;


• design and integrity of structures;

• quantity of contaminants or water to be discharged;

• quality of discharges;

• monitoring of discharges; and

• scour protection.

Activities that require a discharge permit under section15(1)(b) include discharges of leachate from closedlandfills to groundwater, discharge of leachate fromoperating landfills to groundwater, and spray irrigationof leachate onto land.

Discharge permits for discharges of contaminants onto,or into land, in circumstances that may result in con-taminants entering water at landfills, generally containconditions relating to:

• location of discharges;

• liner and leachate collection systems;

• landfill cover system;

• quantity of leachate discharge;

• leachate monitoring;

• groundwater monitoring;

• surface water monitoring;

• contingency measures for unacceptable levels ofgroundwater or surface water contamination; and


Discharge to Air

Landfills require a discharge permit for any dischargeof water or contaminants into air unless expresslyprovided for by a regional plan, proposed regionalplan, resource consent or a regulation.

Three types of discharges to air may occur:

• the emission of decomposition gases such as meth-ane, or other greenhouse gases, and odorous com-pounds;

• dust; and/or

• smoke resulting from the burning of rubbish.

It is important to note that open burning in a landfill isillegal for most sites unless allowed by a regional plan.Under section 418 of the Resource Management Act,only those activities that were legal under the Clean AirAct can continue under the Resource Management Actuntil it is restricted by a regional plan. Open burning at

landfills was banned under the Clean Air Act 1972, andis therefore illegal under the Resource ManagementAct 1991.

Furthermore, a variety of hazards arise when burningoccurs within a landfill site, and these may presentsignificant risks to both the health and safety of sitepersonnel and the public. The Health and Safety inEmployment Act 1992 places specific requirements onemployers and those in control of a place of work, toprevent harm to employees (section 6 of the Act) andothers (sections 15 and 16 of the Act) who may beaffected by activities at the workplace. There wouldseem little doubt that fires at a landfill, whether plannedor accidental, would be regarded as giving rise to anumber of significant hazards, any of which may posea risk to employees in the workplace.

Discharge permits for discharges of contaminants intothe air from landfills generally contain conditionsrelating to:

• compliance provisions for effects of odour and dustdischarges;

• monitoring for landfill gas discharges and migra-tion;

• collection and flaring or utilisation of landfill gas;

• operation, performance and monitoring of landfillgas flares; and

• odour monitoring provisions (for example “sniff”panels) in some circumstances.

Water PermitsLandfills require a water permit from a regional coun-cil for the collection and control of stormwater unlessit is expressly allowed by a rule in a regional plan orproposed regional plan, or a resource consent, or is anexisting use under section 20 of the Act.

In practice, regional councils generally require waterpermits for diversion or damming of natural streams onor around the landfill site and taking of groundwater bya groundwater control system. A water permit may alsobe required for the diversion of stormwater around alandfill site. In some cases a single consent may beused to enable all diversions or takes within a singledefined catchment. In others, a separate permit may berequired for each separate diversion.

Water permits for the taking, use, damming or diver-sion of water at landfills generally contain conditionsrelating to:

• location of takes, dams or diversions;

• design and integrity of structures; and


• scour protection.

Land Use Consents“Use of land” includes “any deposit of any substancein, on, or under the land” (section 9(4)(d) of the Act).Under section 9, no person may use land in a mannerthat contravenes a rule in a district plan or proposeddistrict plan, or a regional plan or proposed regionalplan, unless allowed by a resource consent or hasexisting use rights.

Since it would be unusual for a regional or territorialauthority to make any general provision for a landfillwithin a plan or proposed plan, under normal circum-stances a landfill will require a land use consent fromeither a territorial authority, regional authority, or both.

Land use consents issued by territorial authorities inrespect of landfills may contain conditions relating to:

• development plans;

• noise;

• roading and traffic;

• litter;

• nuisance from birds, flies and vermin;

• fencing;

• separation distances;

• site rehabilitation;

• landscaping and visual effects; and


A land use consent may also be necessary from theregional council if a landfill proposal involves excava-tion or filling, or is otherwise contrary to the provisionsof a regional policy statement or a regional plan.

Land use consents for excavation or filling generallycontain conditions relating to:

• erosion; and

• silt control.

The resource consent process is outlined in more depthin Section 2.4.

Coastal PermitsIn the coastal marine area (that is, below mean highwater spring tide), the regional council is responsiblefor assessing coastal permit applications. A coastalpermit would be required before a landfill could be

developed in the coastal marine area (for example, inthe intertidal area) or, if there is likely to be anydischarge into the coastal marine area.

Subdivision ConsentsSubdivision is the responsibility of district/city coun-cils. Subdivision may be a necessary part of a landfillproject if there are roads to vest in the council orreserves to be set aside as a consequence of the landfilldevelopment.

Existing Use RightsIn some circumstances, landfills that were establishedsome years ago may be able to claim existing userights. Sections 10 and 20 of the Resource Manage-ment Act provide requirements that must be met if landis to continue to be used in a manner that contravenesa rule in a district plan or a proposed district plan. Thefirst is that the land use was lawfully established beforethe rule became operative. This can include a land useestablished by a designation that has subsequentlybeen removed.

The second requirement is that the effects of the use arethe same or similar in character, intensity and scale tothose which existed before the rule became operativeor the proposed plan was notified or the designationwas removed.

The Act also provides that:

• consents granted under the Town and CountryPlanning Act become land use consents (section383); and

• water rights under the Water and Soil ConservationAct 1967, are deemed to be ‘existing rights andauthorities’ (section 386), and become either waterpermits or discharge permits, expiring on either 1October 2001 or 2026, depending upon their origi-nal duration; and

• for the numerous landfills that did not have waterrights and/or land use consents at the time ofenactment of the Resource Management Act 1991,no lawful consents exist.

The Suite of Typically NecessaryConsentsThe establishment of a landfill under the ResourceManagement Act 1991 may require a number of con-sents from a regional council and/or district/city coun-cil. The number and type of consents required, and thedetail of information necessary may vary depending onthe type of landfill, and its siting and surroundingenvironment.


The types of consent that may be necessary for alandfill, and the authorities from which they must besought are set out in Table 2.1.

DesignationsA designation is a provision in a district plan, thatprovides for a particular public work or project of arequiring authority. Designations for landfills can onlybe required by a Minister of the Crown, or a regional,district or city council. In the case of landfills, thedesignation procedure is not available to private or-ganisations.

A designation for a landfill provides for the use of theland as a landfill. However, resource consents from theregional council will still be necessary for excavation/filling, discharges of contaminants and stormwater,and use of water.

A subdivision consent from the district/city councilmay still be necessary, but the presence of a designa-tion does away with the need for a land use consentfrom the district council.

A notice of requirements to designate land can bepublicly notified as if they were applications for re-source consents and there is provision for public sub-mission and appeal. Designations with respect tolandfills generally contain conditions similar to condi-tions in a land use consent.

District PlansCouncils may make provision for landfills in theirdistrict plans under Clause 6, Part II, of the Second

Schedule. This states that one of the matters that maybe included in the district plan is:

“The scale, sequence, timing and rela-tive priority of public works, goods andservices including public utility networksand any provision for land used or to beused for a public work for which theterritorial authority has financial re-sponsibility.”

Any person can request a change to an operativedistrict plan that would make provision for a landfill(section 73). This request could be for either:

• a site-specific provision; or

• a general provision within the district plan thatwould permit landfills to be established, subject tocertain criteria.

An application for a plan change is a public process,with extensive opportunity for public submissions.Any person who has made a submission has a right toappeal the council’s decision to the Environment Court.

A request for a plan change requires a considerableamount of information. Reference should be made toPart II of the First Schedule to the Act that sets out theinformation requirements. In general terms this in-cludes:

• a clear definition of the change sought; and

• a description of the environmental results antici-pated as a result of the change.

A description of the environmental results anticipated

Authority Consent Type Purpose

Regional Council Discharge Permit Discharge of contaminants to:

• land

• water

• air

Water Permit The taking, use, damming or divertingof water

Land Use Consent Excavation or filling of the land

District /City Council Land Use Consent Use of land for purposes of a landfill

Subdivision Consent This may be necessary if the project involvesany amalgamation of titles, vesting of roadsor reserves, or partition of the land intodifferent ownerships

Table 2.1 Regulatory authority resource consent responsibilities


as a result of the change should be prepared in accord-ance with the Fourth Schedule (of the Act) and anassessment of any significant adverse effects on theenvironment is necessary.

Section 32 of the Act also requires that the costs andbenefits of the proposed change, and the alternatives,and the need for the change, are adequately investi-gated and considered before the plan change is adopted.Effectively this means for a private plan change that thework must be done before the application for thechange is made with the council.

The approximate time to prepare the necessary docu-mentation to support a plan change is 6-12 months.Once the application has been lodged, the approximateminimum time to obtain a decision from the council isabout 12 months.

An additional 6-12 months should be allowed forappeals to the Environment Court.

Consultation/Liaison with ConsentAuthoritiesThe appropriate regulatory authorities, be they re-gional, district or city councils, should be consulted atthe earliest opportunity to confirm their requirementsin respect of resource consent applications and toestablish pre-application consultation links with staff.The advantages of this early liaison cannot be over-stated.

Consultation with tangata whenua should be under-taken, and any affected parties identified and con-sulted.

Consultation is important to ensure the resource con-sent application is sufficiently clear, thorough andcomplete in its assessment of effects on the environ-ment.

Enforcement Mechanisms in theResource Management ActThe Act provides a number of enforcement mecha-nisms to ensure compliance with the district and re-gional plan requirements, designations and resourceconsents. There are three levels of enforcement:

• administrative enforcement, which may take theform of declarations, abatement notices, excessivenoise directions and infringement offence provi-sions, all instigated by the relevant territorial au-thority or regional council;

• civil enforcement through enforcement orders, is-sued by the Environment Court at the instigation ofa council or a member of the public; and

• offence provisions.

Administrative Enforcement

The Environment Court may issue declarations toclarify any matter concerning the Act or a plan. Dec-larations are usually used to clarify responsibilities orpowers under the Act, or to determine the correctinterpretation of a document.

Abatement notices are used to enforce compliancewith the Act and various planning instruments, and toensure that the duty to avoid adverse effects on theenvironment is observed. Enforcement officers ap-pointed by local authorities can issue abatement no-tices. A person must comply with an abatement noticeserved on them within the period specified in thenotice, unless they decide to appeal.

Civil Enforcement

Only the Environment Court, on application, can makeenforcement orders. The potential scope of enforce-ment orders is wide. Orders may require a person tocease a certain activity or take positive action to rem-edy adverse effects on the environment. Interim en-forcement orders are designed for use in emergencysituations and are, in that sense, similar to injunctionproceedings. If a Judge considers it necessary, thenotice and hearing requirements can be dispensedwith, so that interim enforcement applications may bedealt with on an ex parte basis where the person againstwhom the order is sought is not present.

Examples of what may be required in an enforcementorder issued against a landfill operation include:

• cessation or prohibition of an activity that contra-venes or is likely to contravene the Resource Man-agement Act 1991, any regulations, rule in a plan,requirement, heritage order, or resource consent;

• cessation of an activity that is likely to be noxious,dangerous, offensive or objectionable, or where ithas or is likely to have an adverse effect on theenvironment. It should be noted, however, that thisremedy is not available in certain circumstanceswhere the person is acting in pursuance of a re-source consent or rule in a plan (section 219(2));

• compliance with any rules, regulations, heritageorder or resource consent; and

• avoidance, remedy or mitigation of actual or likelyadverse effects.

Offence Provisions

The most serious offences are punishable by a fine of


up to $200,000 and a prison sentence of up to two years.For a continuing offence, a fine of up to $10,000 perday may be imposed. Any person may lay an informa-tion (the first step in a prosecution) within six monthsof the time when the offence first became known, orshould have become known to the local authority inquestion. These are offences of strict liability, whichmeans that it is not necessary to prove that the defend-ant intended to commit the offence.

An ‘emergency’ defence is available where a defend-ant is able to establish that an event or action was anemergency measure, that the defendant’s conduct wasreasonable and that following the event he or sheadequately mitigated or remedied any adverse effectson the environment.

Alternatively, a defence may be made out by establish-ing that the event or action was beyond the defendant’scontrol by virtue of an event such as a natural disaster,mechanical failure or sabotage. To succeed with itsdefence, the action or event must not have been reason-ably foreseeable by the defendant, and he or she musthave also adequately mitigated or remedied any ad-verse effects on the environment.

A defence of due diligence is available in circum-stances where the defendant did not know and couldnot reasonably be expected to have known of theoffence, or where the defendant took all reasonablesteps to prevent the commission of the offence. Ineither case, the defendant must additionally prove thatall reasonable steps were taken to remedy the effects ofthe offence.

2.4 Resource ConsentApplication Process

Resource Consent Process “Resource consent” is an umbrella term covering fivedifferent types of consents. A resource consent permitssomething to be done that would otherwise be re-stricted by a rule in a plan. As indicated already, aresource consent includes:

• discharge permit;

• water permit;

• land use consent;

• coastal permit; and

• subdivision consent.

Landfill activities are not usually provided for specifi-cally within district or regional plans and resourceconsents are usually required.

When lodging applications for resource consents, anapplicant must also provide an Assessment of Effectson the Environment (AEE) with respect to the pro-posal. This assessment is required to be in sufficientdetail to enable both the consent agency and membersof the public to form an appreciation of the effects ofthe proposal. The scope of an assessment is prescribedin the Fourth Schedule to the Act.

An AEE should also contain a description of how alandfill will be operated, to minimise any adverseeffects on the environment. It may contain variousmanagement plans covering such matters as routineoperations, daily cover, leachate collection and treat-ment, control of noise, rodent and bird pests, andlandscaping. It should also include the outcome of anypublic consultation that has been undertaken.

NotificationA presumption in section 94 of the Act is that applica-tions for resource consents will be publicly notified.Experience has been that most councils do in factnotify applications for resource consent in respect oflandfills. Notification provides an opportunity for anymember of the public to lodge a submission either infavour of or in opposition to a proposal. Submitters canalso present their submissions in person at the councilhearing of submissions, and subsequently take an ap-peal to the Environment Court if they are dissatisfiedwith the decision of the council.

Applications may proceed without public notificationin certain circumstances. These include:

• where the consent of persons affected has beenobtained in advance; and

• where any adverse effects on the environment areminor.

How Long Does the Resource ConsentProcess Take?Once an application for a resource consent has beenlodged, the consent authority first decides whether ornot to notify the application. The timing of each proc-ess is set out below.

Notified application

• Ten working days to publicly notify the applica-tion.

• Twenty working days to receive submissions.

• Twenty-five working days after closing of submis-sions to hold a hearing. At least 10 working daysnotice must be given of the time and place of thehearing.


• Council’s decision within 15 working days of thehearing.

• Appeal to the Environment Court by applicant orany submitter.

Note that under section 92 of the Act, the council mayrequest further information from the applicant at anytime up to the time of the hearing. Once such a requesthas been made the consent authority may postpone thenotification of the application or the hearing of theapplication until it is satisfied that the information hasbeen provided.

Approximate time to decision — 70 working days(allow four months).

Appeal time — an additional 6-12 months minimum.

Non-notified application

• decision made not to notify within 10 working daysof receipt of all further information;

• assessment of application;

• council’s decision within 20 working days of re-ceipt of all further information;

• appeal to the Environment Court by applicant only(in respect of refusal or condition on which theconsent is granted).

Note that section 92 (further information required) canapply to the non-notified process as well.

Approximate time to decision — 30 working days (sixweeks).

Appeal time — an additional 6-12 months minimum,only if the applicant is not satisfied with the conditionsof consent, since there will have been no submitters inopposition.

Council Hearings and Appeal RightsIf resource consents are required from both a territorialauthority and a regional authority, joint hearings areoften held. An applicant and any submitter may appearand present evidence. The application is usually heardby a sub-committee of elected council officers orindependent commissioners. A council planner and/ortechnical expert(s) will attend the hearing to assist the

committee where necessary. Involvement in a councilhearing does not create any liability for any otherparty’s costs; however, the applicant pays the cost ofpreparation for the hearing and council’s costs. Thesecosts can be significant for an applicant.

If consent is refused, or granted subject to conditionsthe applicant does not accept, the applicant may appealto the Environment Court. If consent is granted, anysubmitter has a right of appeal. Any appeal must belodged within 15 days of receiving the decision. Oncesuch an appeal is lodged, it will typically take at leastfour months before the Environment Court sets ahearing date.

An Environment Court decision may be appealed tothe High Court and Court of Appeal, but only on pointsof law.

The Environment CourtThis court is a separate and independent judicial bodyestablished under the Act. It has jurisdiction for allappeals to decisions under the Resource ManagementAct.

The appeal process is a lengthy one. An appeal to theEnvironment Court is likely to delay a proposal byabout 12 months or more.

The costs of bringing an appeal in the EnvironmentCourt are substantial and include the preparation oflegal submissions and evidence from the applicant and,if necessary, technical experts, and attendance at thehearing. Costs for preparing and attending an appealhearing escalate rapidly for appeals requiring a varietyof experts to be involved.

Appeals in the Environment Court are open to award ofcosts. Typically, a successful party may seek costsfrom the other parties, and the Environment Courtmakes this decision.

A party may seek security for costs from another partyin litigation, where there is an apprehension that thatparty may not have sufficient funds to meet a success-ful claim for costs.

Many appeals are resolved by mediation and negotia-tion. The Court actively encourages this approach andprovides expert assistance where necessary.

Landfill Siting • 13

Chapter 3Landfill Siting

3.1 IntroductionSelection of appropriate sites for new landfills is fun-damental to the long-term protection of the environ-ment, both human and physical, from the potentialeffects of landfilling operations.

Engineered liner systems have a finite lifetime soconsideration needs to be made of the ability of theunderlying materials to keep discharges from the site toa level that will not cause significant adverse effects onthe surrounding environment.

New landfill proposals are commonly subject to sig-nificant public debate and opposition. Traditionally,opposition has been in response to the likelihood thatparticular effects will impact selectively on some sec-tions of the community.

Examples of impacts include traffic hazards, noise,unpleasant odours, windblown litter and dust, an in-crease in the populations of vermin and wild cats, andthreats to household water supplies.

In addition, some people are philosophically opposedto the idea of continued landfilling as a means of refusedisposal.

Even though there is a national trend towards fewer,larger landfills, with consequent economies of scale,large new facilities are not more appealing to potentialhost communities.

The countryside of New Zealand is becoming morepopulated. As a result, becomes increasingly difficultto find potential landfill sites that do not pose somesort of conflict with other uses.

Opposition to new landfill sites can be expected tocontinue, and probably intensify in future. Oppositionto a landfill proposal can be manifested by attacks onboth the specifics of a proposal and the whole processof site selection.

This section addresses the following:

• landfill siting philosophy;

• strategic planning;

• site selection process; and

• landfill siting criteria.

3.2 Landfill Siting PhilosophyThe philosophy behind these landfill site selectionguidelines is to assist in the selection of sites thatprovide both a high level of containment, through theirnatural, geological, hydrogeological and topographi-cal characteristics, and are located so as to causeminimum disruption to the community in the areasurrounding the site.

The use of a robust site selection process and sitingcriteria to select the most appropriate landfill sites willhelp avoid or reduce potential environmental problemsby reducing the potential impact on people and envi-ronmental receptors. In addition, appropriate siteselection may:

• reduce reliance on engineered liner systems;

• reduce requirements for technically-based contin-gency and mitigation measures;

• allow more efficient and effective site manage-ment;

• result in savings in development and operatingcosts;

• reduce levels of public concern and opposition; and

• avoid potential delays in obtaining the necessaryresource consents.

The criteria set out in this section are applicable to allmunicipal solid waste landfills, whether for small ruralcommunities or large metropolitan areas. The samebasic processes apply irrespective of the scale of opera-tion.

3.3 Strategic PlanningSelection of a landfill site should ideally involve con-sideration of strategic waste management issues.

The need for a new landfill site usually results fromeither a community’s solid waste management plan-ning process, or a private company’s commercial deci-sion (or possibly a combination of the two).

Consultation undertaken during the strategic planningphase should, ideally, be linked through to appropriate


stages in the site selection process to provide continu-ity with respect to the various individuals, groups orcommunities involved.

Issues to consider during the strategic planning stageinclude:

• size of site required to meet current and futuredisposal requirements;

• potential for, or likely effects of, the use of otherwaste management options including

— reduction

— re-use

— recycling

— composting, and

— incineration

• waste management plan of the district in which thelandfill is to be located;

• waste management plans of the districts that thelandfill will service;

• regional policy statement and applicable regionalplan(s);

• location with respect to communities from whichthe refuse will come; and

• access to transport, either on the appropriate stand-ard of roads or rail access.

3.4 Site Selection ProcessSiting of solid waste landfills requires a careful exami-nation and evaluation of all of the parameters that couldpotentially result in adverse effects on the environ-ment.

The site selection process and criteria set out belowshould not be viewed as absolute. All potential loca-tions need to be considered in the light of site-specificcharacteristics, which may result in some parametersbeing given a greater weighting than others.

The primary consideration in the landfill siting processshould be the selection of a location, which reduces thepotential for adverse effects on the environment, basedon sound scientific and engineering principals.

Landfill siting should also take into account, designand operational aspects of the landfill. Many siteparameters can be improved by engineering designand/or potential adverse effects mitigated through ap-propriate operational methods.

Siting decisions should also be made with regard tolocal community issues, including needs, expectationsand resources.

While landfill siting should be based primarily ontechnical factors, community perception and valuesmay also be critical to the acceptability of a landfill site.Therefore, it is essential to involve the local commu-nity early in the site selection process.

The site selection process should normally include thefollowing processes:

• initial desk top study;

• site investigations;

• economic assessment (repeated at different stagesof the process); and

• consultation (at different stages of the process).

Initial Desk-top StudyA number of possible localities or sites should beidentified using the following general criteria:

• geology;

• hydrogeology;

• surface hydrology;

• stability;

• topography; and

• compatibility with surrounding land use.

Information from a number of sources can be used inthis process, including:

• geological maps;

• topographical maps;

• meteorological rainfall maps;

• Department of Conservation conservation man-agement strategies;

• Historic Places Trust Register;

• district plans;

• regional plans; and

• local knowledge.

Site InvestigationsSite investigations should generally follow a stagedapproach using:


• preliminary investigations;

• initial technical investigations;

• non-technical investigations; and

• detailed technical investigations.

Preliminary Investigations

A walkover survey should be undertaken at sites iden-tified by the desk-top study. Each site should beassessed with respect to the criteria listed above. Anyobvious fatal flaws with respect to geology, surfacehydrology and stability should also be identified.

Following this survey, sites should be ranked to deter-mine a shortlist of sites for further investigation.

Care should be exercised when ranking sites as:

• design and operational techniques may elevate, orreduce, the initial status; and

• community issues may affect the status of a site.

Initial Technical Investigations

The purpose of initial technical investigations onshortlisted sites is to identify potential fatal flaws andreduce the shortlist of identified sites to one or moresites for more detailed technical investigations.

Initial investigations should include:

• detailed mapping of site geology;

• geotechnical investigation, by way of pit investiga-tions to assess site soils with respect to contain-ment, stability, seismic risk and suitability for lin-ing and cover material;

• identification of nearby groundwater wells andusers;

• review of historical information on groundwaterlevel and quality, if available;

• shallow groundwater bores to assess hydrogeology— ideally these bores should be located where theycan be used for monitoring during landfill opera-tion and following closure, if the site proceeds;

• sampling of surface water quality and, possibly,groundwater quality; and

• assessment of sensitivity of biota and fauna at thesite and downstream.

Non-technical Investigations

Non-technical issues such as local social, cultural and

amenity values can be the issues of greatest concern tothe local community, and can be the determining factoron site acceptability. The following factors should beassessed before detailed technical investigations areundertaken at a site:

• location of site neighbours;

• location of any sites of cultural significance, in-cluding, rivers, streams, Marae, ancestral land,waahi tapu and other taonga (it should be noted thatsome of these site are not always identifiable);

• potential for nuisances associated with odour, ver-min, birds and flies, noise, litter, dust and visualeffects;

• access to the site and potential traffic effects; and

• location of sites of historical significance.

Detailed Technical Investigations

The results of initial technical and non-technical inves-tigations, coupled with preliminary economic assess-ments, should result in a shortlist of priority sitesworthy of more detailed technical investigations.

An investigation programme should be developed on asite-specific basis. It should address the site selectioncriteria detailed in Section 3.5, and potential design,operational and monitoring requirements.

Following detailed investigations, economic assess-ment and consultation, it should be possible to deter-mine the most appropriate location with which toproceed with the resource consent application process.

Economic AssessmentA preliminary economic assessment should be under-taken for shortlisted sites so that the costs of develop-ing and operating landfills at the different sites can becompared.

This assessment should be undertaken using a fullcosting process, in which all real, definable and meas-urable costs from all sources, which are paid for by thelandfill operator, are identified.

The types of costs that need to be identified anddetailed include:

• management, administration and organisationaloverhead costs;

• planning and resource consent costs;

• land cost;

• development costs, including investigations, de-


sign and construction;

• operational costs;

• monitoring costs;

• closure, rehabilitation and aftercare costs; and

• potential mitigation costs.

Where incomes, other than gate charges, are expected(for example, sale of landfill gas, lease of land not usedfor landfilling) these should also be included.

Comparison should be made in terms of present valueper unit volume, or tonnage, of landfill capacity. Sen-sitivity with respect to changing costs for key variablesshould also be checked.

The costs of transporting refuse to different landfillsites should also be taken account of when comparingsites.

Economic assessments should be repeated as theshortlisted number of sites is reduced and more infor-mation on site conditions and engineering require-ments becomes available.

Additional information on full costing of landfill op-tions is provided in the Landfill Full Costing Guide,MfE (1998).

ConsultationConsultation with the community is a critical compo-nent of any landfill site selection process.

All consultation undertaken with persons interestedin or affected by a proposal should be formally re-corded.

While the decisions on the type and degree of consul-tation will be specific to each different proposal, theplanning of the site selection process should considerthe following:

• which parties should be involved in each stage ofthe selection process;

• the ways in which parties should be involved; and

• the roles of different parties in the process.

The use of community working parties or liaisongroups can be an effective means of identifying andtaking account of potential community concerns fromthe strategic planning stage onwards.

There are no standard requirements as to the formconsultation must take. Any form of oral or writteninterchange that allows adequate expression and con-

sideration of views is appropriate. There is also nostandard as to the duration of the consultation. It couldrange from one telephone call to many meetings overa number of years. However, the following providesome useful principles and practices to be guided by:

• Ministry for the Environment practical guides toconsultation, including;

— Striking a Balance: A Practice Guide on Consul-tation and Communication for Project Advo-cates (September 1999); and

— Case Law on Tangata Whenua Consultation(1999).

• The New Zealand Association for Impact Assess-ment, which has members with considerable expe-rience of consultation activities.

There is a growing body of case law regarding essentialprinciples of good consultation. The most frequentlycited court judgement in New Zealand comes from thecase of Wellington International Airport Ltd v Air NewZealand [1991]1 .

These principles from the Appeal Court decision pro-vide good guidance for those planning or involved in aconsultation process:

• a description of the proposal should be in its con-ceptual form and not yet finally decided upon;

— start consultation early

— give yourself the chance to benefit from others’suggestions

— don’t be embarrassed by finding a fatal flaw justwhen you’ve finished the plan

• allow sufficient time for consultation;

— other people are busy too

— people need time to digest information

— try to accommodate interest groups’ existingmeeting schedules (e.g. monthly); don’t im-pose the burden of additional meetings if thiscan be avoided

• make a genuine effort to consult;

— be proactive

— get out and consult

— don’t expect people to come to you

1 New Zealand Law Reports 671


— think of a variety of ways to exchange informa-tion

• conduct the process in mutual good faith;

— show that you are trying to understand howother people see the proposal

— be open to any suggestions for alternatives ormitigation of effects

— be prepared to offer your own suggestions un-solicited

— cross check with others — beware of capture bythe “squeeky wheel”

• provide enough information to enable the partybeing consulted to make intelligent and usefulresponses;

— don’t hold back information because you thinkpeople will react negatively to it

— don’t adopt the attitude that it’s alright so longas you present relevant information at the hear-ing

— the sooner people know about issues and ef-fects, the more time there is to explore mitiga-tion possibilities

• hold meetings, provide relevant and further infor-mation on request;

— if you offer further information, provide itpromptly

— don’t be afraid to call people’s bluff — ask forevidence to back up assertions

• r e-open the consultation process if necessary;

— be flexible and responsive to reasonable andgenuine requests — but don’t be spineless.

It should be noted that consultation is not:

• merely telling or presenting;

• intended to be a charade; or

• the same as negotiation.

3.5 Landfill Siting CriteriaThe following landfill siting criteria detail the keyissues that need to be considered when:

• identifying potential landfill sites; and

• planning site investigations and assessing the

suitability of a site for landfilling.

It is unlikely that any site will meet all criteria. There-fore the assessment of the suitability of a site for alandfill becomes a balance of trade-offs with respectto:

• comparison of site characteristics with alternativelocations;

• the potential for engineered systems to overcomesite deficiencies;

• methods of operation proposed for the site; and

• social and cultural issues associated with the site.

In order to minimise future risk to the environmentfrom landfilling activities, primary consideration shouldbe given to key issues and potential fatal flaws withrespect to geology, hydrogeology, surface hydrologyand site stability.

GeologySuitable geology is important to ensure containment ofleachate in the long term, or in the case of failure ofengineered containment systems. Geology should beassessed with respect to the movement of leachate andlandfill gas.

Areas of low permeability in-situ material are pre-ferred. Because engineered liner systems have a finitelifetime, the ability of the underlying materials tominimise the potential for liquids to migrate out of thelandfill into the environment should the liner eitherdegrade, tear, or crack needs careful consideration.

Due to risk of off-site movement of leachate andlandfill gas, it is generally undesirable to site a landfillin areas with the following characteristics:

• high permeability soils, sands, gravels, or sub-strata;

• high permeability seams or faults; and/or

• Karst geology — regions with highly soluble rocks,sinks and caverns (for example, limestone areas).

Where a landfill is developed in these geologicalenvironments, the design should incorporate a higherlevel of engineered leachate containment and appro-priate contingency measures.

An assessment of geology and site soils should con-sider:

• the availability of on-site materials for lining, coverand capping. Soils with a high percentage of clayparticles (but which are workable in wet condi-tions) are generally the preferred soil type;


• the suitability of on-site materials for the construc-tion of dams and drainage systems;

• potential sediment management problems, withhighly erodible soils;

• existing site contamination and discharges, ifpresent;

• suitability for on-site disposal of leachate by sur-face or subsurface irrigation; and

• the potential effects of failure of leachate contain-ment and collection systems.

Geological factors also influence stormwater, silt andgroundwater controls, the containment and control ofleachate and gas, as well as the availability of finalcover materials.

Site StabilitySite stability should be considered from both short-and long-term perspectives, including the effects ofsettlement.

It is generally undesirable to site a landfill in thefollowing areas:

• areas subject to instability, except where the insta-bility is of a shallow or surface nature that can beovercome, in perpetuity, by engineering works;

• active geological faults;

• areas of geothermal activity; and/or

• Karst terrain — regions with highly soluble rocks,sinks and caverns (for example, limestone areas).

In assessing the suitability of a site for a landfill thelocal soils need to be considered with respect to thefollowing:

• Localised subsidence areas. Differential move-ment could render a landfill unusable due to ruptureof liners, leachate drains or other structures.

• Landslide prone areas. The future weight could,through a wide variety of mass movement,destabilise the landfill. Instability may also betriggered by earthquakes, rain, freezing and thaw-ing, and seepage.

• Local/onsite soil conditions that may result in sig-nificant differential settlement, for example com-pressible (peat) or expansive soil, or sensitive claysor silts.

Where there is potential seismic impact, the ability todesign containment structures, including liner, leachate

collections systems and surface water control systems,to resist the maximum acceleration in lithified earthmaterial for the site, must be assessed.

HydrogeologyA suitable hydrogeological location is important toprotect groundwater resources and understand the likelyfate and rate of discharge of contaminants which mayenter groundwater.


• areas overlying drinking water aquifers; and/or

• areas where, after taking into account specificdesign proposals, there could be a risk of causingunacceptable deterioration of the groundwater qual-ity in the locality.

In assessing the suitability of a site for a landfill withrespect to hydrogeology, the following need to beconsidered:

• depth to water table and seasonal water table fluc-tuations;

• location of aquifer recharge areas, seeps or springs;

• distance to water users;

• sensitivity of water users;

• dispersion characteristics of aquifers;

• variations in groundwater levels;

• rate and direction of groundwater flow;

• existence of groundwater divides;

• baseline water quality; and

• the potential effects of failure of leachate contain-ment and collection systems.

Surface hydrologyThere are risks of surface water pollution if landfills aresited in close proximity to waterways. The potentialimpact of water pollution is greater in those waterwaysused for drinking water or aquaculture.


• flood plains — these are generally areas whichcould be affected by a major (1 in 100 year) floodevent;

• land that is designated as a water supply catchmentor reserves for public water supply;


• gullies with significant water ingress, except wherethis can be controlled by engineering works with-out risk to the integrity of the landfill;

• water courses and locations requiring culvertsthrough the site and beneath the landfill (if water-ways are unable to be diverted); or

• estuaries, marshes and wetlands.

In assessing the suitability of a site for a landfill, thelocal surface hydrology needs to be considered withrespect to the sensitivity of the receiving environment,including the following:

• the proximity of waterbodies or wetlands;

• the risks of pollution of waterbodies used for drink-ing water or aqua-culture;

• sensitive aquatic ecosystems; and

• potential for impact from cyclones and tsunamis.

An assessment of the stormwater catchment above thesite should be made to identify the extent of anydrainage diversion requirements that may need to beaddressed.

TopographySite topography can reduce or increase the potential foradverse effects on the environment from odour, noise,litter, and visual effects on neighbouring properties.

In considering potential landfill sites an assessment ofthe potential for existing topographical features toassist in minimising impacts should be made.

Modest slopes enable easier stormwater control,leachate control and site stability measures, as well asfacilitating the operation of the site. Engineering tech-niques can also improve site stability.

Climatic ConditionsClimatic conditions will have an influence on thechoice of a preferred site. The following should beconsidered during site selection.

Rainfall

Areas where topographical features are likely to causehigher than average rainfall are generally undesirable.Landfills in higher rainfall areas require greater atten-tion to drainage than those in drier areas.

Sunshine

Higher sunshine areas and north facing slopes reduceinfiltration by increased evaporation.

Wind

Natural shelter from winds will reduce the nuisance ofwindblown refuse and dust. Escarpments or valleysfacing the prevailing wind should normally be avoided.

Environmentally Sensitive AreasLandfills should generally be located to avoid areaswhere sensitive natural ecosystems would be adverselyaffected, such as:

• significant wetlands;

• inter-tidal areas;

• significant areas of native bush including the ForestPark and areas able to comply with the require-ments for QEII Trust status;

• recognised wildlife habitats;

• national/regional and local parks and reserve lands(for example, cemeteries); and

• any areas where release of contaminants from thesite could severely affect fish/wildlife/aquatic re-sources.

Other areas that should be avoided include:

• sites of historical or cultural significance; and

• historic and scenic reserves.

Access and trafficLandfill development and operations can generatesignificant flows of heavy vehicle traffic. Thereforesite access should be as close as possible to main feederroutes. The following need to be considered whenlocating and determining access to landfills:

• type and number of vehicles accessing the site;

• other types of traffic using feeder roads;

• the standard and capacity of the road network, withrespect to accommodation of traffic generated bythe landfill;

• whether the traffic can avoid residential areas;

• road safety considerations with respect to the landfillentrance (vehicles using the landfill should not berequired to queue on the highway).

Compatibility with surrounding land useThe proximity of a potential landfill site to existing, orproposed, land uses needs to be considered.

Separation distances, or buffer areas, can be used to


preserve the amenity of surrounding areas. The re-quirement for and extent of buffer areas should bedetermined on a site-specific basis. Where possible,the buffer area should be controlled by the landfilloperator.

An assessment of the suitability of a site for a landfill,and/or appropriate buffer areas, with respect to reduc-ing the potential for adverse effects on surroundingland use should consider:

• existing property boundaries and ownership;

• statutory planning constraints including;

— zoning (the protection of amenity associatedwith residential, commercial or rural zones fromnuisances associated with odour, vermin, birdsand flies, noise, litter, dust and visual effects, orfailure of containment, leachate collection orlandfill gas systems)

— land designated for a special purpose (for exam-ple, hospitals, schools)

• airport safety; and

• proximity to sites with cultural or historical signifi-cance.

Leachate ManagementLandfill siting should take account of the potentialmethods of leachate treatment and disposal and itseffect on site neighbours.

Methods of leachate treatment and/or disposal couldinclude the following:

• Discharge to community sewerage system, with orwithout treatment.

• Discharge to land by spray or subsurface irrigation,with or without treatment. Effects of runoff, odoureffects from leachate storage ponds, odour andspray drift from irrigation systems and effects onsoil structure need to be assessed.

• Discharge to natural water after treatment. Culturalconsiderations need to be taken into account.

• Treatment by recirculation within the landfill. Ef-fects of increased landfill gas production, odourand potential for differential settlement, leachatebuild-up on the base of the landfill, decreasedstability of the refuse mass and leachate breakouton surface slopes needs to be considered.

• Evaporation using heat generated from the com-bustion of landfill gas.

Landfill Gas ManagementLandfill gas can give rise to adverse effects such as:

• odour nuisance;

• greenhouse effects of methane;

• migration in surrounding sub-strata;

• vegetation die off within or on the completed landfillsurface and adjacent areas;

• explosions or fires due to gas release through cracksand fissures at the surface, or in confined spacessuch as manholes, chambers and poorly-ventilatedareas of buildings on or adjacent to the site; and

• asphyxiation of personnel entering trenches, man-holes or buildings on or near the landfill site.

The potential for landfill gas migration in surroundingsub-strata needs to be considered with respect to con-tainment proposals.

Landfill siting should take account of the potentialmethods of landfill gas treatment and disposal and itseffect on site neighbours.

Methods of landfill gas treatment and/or disposalcould include those listed below:

• Venting of landfill gas. Effects of odour and non-methane organic compounds (NMOCs) on siteneighbours need to be assessed. Greenhouse gasemissions should also be assessed.

• Flaring of landfill gas. Visual (light) and noiseeffects of landfill gas flares need to be considered.

• On-site power generation. The effects of generatornoise and backup flares need to be considered.

• On-site treatment or gas stripping prior to off-siteuse. The potential odour effects and effects frombackup flares needs to be considered.

Community IssuesThe local community will have a significant input intodetermining whether or not a site is suitable for devel-opment as a landfill. Many of the issues, which can beof greatest concern to the local community, may not bethose identified through technical studies or investiga-tions.

These issues, many of which are detailed above, in-clude, but are not limited to:

• design life of the landfill;

• nuisances associated with odour, vermin, birds andflies, noise, litter, dust and visual effects;


• the potential effects of failure of containment,leachate collection or landfill gas systems;

• protection of local amenity values;

• traffic effects;

• health risks;

• cultural issues;

• heritage issues;

• loss of property values;

• long-term compliance with consent requirements;and/or

• end use of the site.

Consultation and negotiation with the community dur-ing the siting process is required to determine issues ofsite-specific importance, the actual, or perceived, risksand appropriate measures to avoid, remedy or mitigateadverse effects on the environment.

Landfill Design • 23

Chapter 4Landfill Design

4.1 IntroductionThe landfill design process is affected by the followingfactors:

• size and scale of the proposed landfill operation;

• site location and characteristics;

• surrounding environment; and

• type of waste to be deposited in the landfill.

Internationally, a range of legislative instruments anddesign guidelines are used to control landfill design.The principal ones relevant to the New Zealand contextare summarised in Appendix 2.

As outlined in Chapter 1, these guidelines focus onmunicipal solid waste landfills.

Many of the principles involved are also relevant to thedesign of cleanfill sites, industrial waste landfills (in-cluding monofills), and to hazardous waste landfills,but these are beyond the scope of these guidelines. Inthe case of cleanfills, most regions have specific provi-sions for the design of such facilities included in theirregional plans.

This section is intended as a guideline for landfilldevelopers, designers and regulatory authorities. Itdoes not attempt to repeat the wide range of designmaterial that already exists, but focuses on key princi-ples and applicable approaches.

Key points to note are:

• the acceptance of any design by a regulatory au-thority will be based on an assessment of actualand potential effects on the environment, whichrequires detailed technical evaluation and justifica-tion; and

• the guidelines refer to designs considered to pro-vide a suitable level of leachate retention, thusproviding a reasonable assurance of protection ofthe receiving environment.

These design guidelines are not prescriptive. They areintended to provide design guidance based on industrybest practice and consistent with processes set out inthe Resource Management Act (1991).


• design philosophy;

• design considerations;

• groundwater management and control;

• surface water and stormwater management;

• leachate management and control;

• leachate containment and liner systems;

• landfill gas management;

• landfill cover systems; and

• construction quality assurance and constructionquality control.

4.2 Design Philosophy

GeneralThe design of a landfill should ensure that biological,biochemical and physico-chemical interactions withinthe waste are promoted, fostering naturally-generatedprocesses that both degrade and stabilise wastes, andultimately render the resulting residues benign to theenvironment.

Enhanced degradation, and consequent reduction inthe time required to stabilise wastes, can be achievedby:

• leachate recirculation;

• bioreactor design and operation; and

• aerobic landfill design and operation.

Leachate recirculation is used at some sites in NewZealand and could be implemented more in the nearfuture, both for leachate treatment and to enhancedegradation. It is discussed in Section 4.9.

A bioreactor landfill is a landfill operated for thepurpose of transforming and stabilising the readily andmoderately decomposable organic waste constituentswithin 5 to 10 years following closure by purposefulcontrol to enhance microbiological processes. A


bioreactor landfill is an extension of a leachaterecirculation landfill, except that water may be addedor substituted for leachate (depending on climaticconditions) and other process-enhancing strategies,such as waste shredding, pH adjustment, nutrient addi-tion and temperature management, may be included.Bioreactor design and operation involves more inten-sive design, management and monitoring to carefullycontrol waste moisture content and leachate chemistryto optimize degradation.

Aerobic landfill design and operation aims to maintainwaste in an aerobic state to achieve faster degradationthan would result from anaerobic breakdown.

Bioreactor and aerobic landfills have not been de-signed or operated in New Zealand to date. They haveconsiderably more detailed design, operations andmonitoring requirements in terms of leachate contain-ment and recirculation and landfill gas management,than more traditional approaches.

Bioreactor and aerobic landfills are currently in thedevelopment and research stage worldwide. Bioreactorand aerobic landfills are unlikely to be developed inNew Zealand in the near future and therefore guide-lines for their design, operation and monitoring areconsidered to be beyond the scope of these guidelines.

However, it is important to continue monitoring over-seas research and trials to identify aspects of bioreactorlandfill design principles, which may be applicable inthe New Zealand situation.

Irrespective of design philosophy, protectinggroundwater and surface water from leachate contami-nation, and people from the adverse effects of landfillgas, remain the principal environmental performanceobjectives with respect to landfill design. While manyof the potential risks associated with landfills can bemitigated by judicious siting, appropriate design iscritical in avoiding adverse effects on the environmentdue to leachate and gas discharges.

International Trends in MSWL DesignInternational trends in MSWL design are summarisedin Appendix 2. In all cases, the primary objective of thedesign process, or stipulated standard designs (legalrequirements in some instances), is to protect theenvironment around the landfill. In the past, the focushas tended to be on the prevention of leachate escapeand consequential effects on groundwater and surfacewater. However, experience in New Zealand andelsewhere over the past 10 years in particular, hasindicated that other environmental issues are also veryimportant. Such issues include odorous waste accept-ance, odour and landfill gas (LFG) control, stormwater

and sediment effects on surface waters, and dust man-agement. Consideration of these issues as part of thedesign process has been incorporated in these guide-lines.

New Zealand Landfill Design TrendsIn New Zealand a number of trends (paralleling over-seas practice) have emerged over the past 10 years orso in relation to MSWL design. These include:

• general improvement in design standards, particu-larly with regard to liner and cover systems, leachatecollection and treatment, and landfill gas control atnew or large sites;

• resistance to upgrading costs and consequent costs,especially for smaller sites;

• centralisation of landfill facilities and an increasein waste transfer to fewer, larger (sometimes sub-regional) facilities;

• greater recognition of the siting sensitivity attachedto landfills and the need for both good design andstringent operating practices;

• adoption of overseas (often USA-based) practicesfor barrier system design (particularly for largersites) in some areas;

• inadequacy of design in the absence of binding(legal) requirements for design and the relative lackof case law under the RMA in some areas;

• an increasing focus on the consequential effectsassociated with larger sites (e.g. local amenity andodour issues); and

• debate over the level of prescriptive design appro-priate in the New Zealand context, and the ad-equacy of “effects-based” design in the absence ofsite-specific performance data.

Design ObjectivesThe design of a municipal solid waste landfill shouldprovide for the following, to a degree appropriate to thelandfill’s size and location:

• a leachate retention system to protect ground andsurface water;

• a leachate management system;

• landfill gas control and/or monitoring;

• a surface water management system;

• site capping and rehabilitation;

• environmental monitoring; and


• site security and ancillary facilities.

In addition, management procedures should be pro-vided to:

• track the types, quantities and sources of wastesreceived;

• adequately monitor the compaction of the wastesand record the position of certain special wastesburials; and

• provide quality assurance procedures for construc-tion, operation and aftercare of the site.

4.3 Design Considerations

Landfill SitingLocation is a primary determinant of the extent towhich a landfill poses an environmental risk. Judiciouslocation of a landfill is the single most effective envi-ronmental management tool. The aim is to minimisethe need for impact mitigation and ongoing manage-ment by selecting a site where natural conditionsprotect environmental quality and where there will notbe adverse impact on existing and future development.

The hydrogeological characteristics of a site have acritical bearing on the need for, and nature of, measuresto control leachate. The potential for environmentaldamage by leachate is more critical if the landfill islocated where there is significant downstream use ofsurface or groundwater resources or where conditionsresult in significant physical or local amenity risk.Landfills can also cause a localised loss of amenity dueto litter, dust, odour, noise, and vermin problems.Proximity to existing and proposed developments, theadequacy of proposed site management proceduresand local climatic conditions are key issues in thisregard.

Investigations and Site CharacterisationInvestigation requirements for a landfill will vary fromsite to site. For a particular site the extent of investiga-tions will depend on:

• geological/geotechnical complexity;

• hydrogeological complexity; and

• site and landfill size.

Sufficient investigations, testing and preparatory workneed to be undertaken to provide:

• characterisation of the geological, hydrogeologicaland geotechnical conditions at the site;

• specific data on site soil properties, including, forrelevant materials, where a soil liner is involved:

— index tests, water content, Atterberg limits,grain size and solid density;

— compaction characteristics (generally the NewZealand Heavy compaction test should be used);

— permeability determined at optimum water con-tent or wetter to simulate soil remoulding atfield target water content (testing should bepressure permeability in a triaxial cell using tapwater as the permeate, or leachate if conditionswarrant); and

— soil security tests, pinhole dispersion, Emersoncrumb test, and, where appropriate, tests onstabilised soils appropriate to the materials andsite location;

• definition and characterisation of surface waters,including receiving waters;

• base contour information for design purposes (col-our aerial photographs are also very useful fordesign development and presentation of concepts);and

• photomontages for assessment of visual and land-scape effects.

Access

Public Access or Not?

Landfilling operations should, ideally, exclude publicaccess to the working face.

There are significant disadvantages in allowing publicaccess to the working area of a landfill. These disad-vantages include:

• lack of control on placing of refuse;

• the need to provide vehicle control, larger refusedischarging areas, and better roading to the work-ing face;

• having a larger (wider) tipping face open, with theconsequences of more litter control problems,greater rodent and bird problems, increasedstormwater infiltration, greater fire risk and morecover material required;

• public health risk, particularly from special wastesand scavenging; and

• additional transportation costs to the community.

A transfer station or reception facility should be estab-


lished, either at the landfill (remote from the tippingface) or at some other location closer to the centre ofrefuse generation.

The distance of the landfill from the centre of refusegeneration will influence the economics of providing atransfer station there, or a reception facility at thelandfill site.

Access to the landfill by larger-volume refuse contrac-tors should be allowed by special arrangement, butonly where it is more economical than accepting thismaterial at a transfer station.

External Access

A landfill will generate heavy vehicle movements. Thestandard and construction of all roads and bridgesforming part of the principal access route to the landfillwill need to be reviewed. Upgrading of roads andbridges may be required.

Access to a landfill should be planned in such a waythat it creates minimal hindrance to existing road users.Access should, where possible, be on sealed roads toreduce dust and mud nuisance, reduce maintenanceand facilitate cleaning.

Careful consideration should be given to the require-ments of the road control authority, that is, Transit NewZealand or the territorial local authority.

Internal Access

The layout of the site entrance should facilitate smoothtraffic flow. Access from a public road should be bya sealed road to the reception control facility, laid outso that queuing vehicles do not back up on publicroads.

The appearance of the accessway is important as thiswill influence the users’ perception and, hence, behav-iour in the landfill area.

Traffic control by clear, attractive signage and appro-priate roading layout is required to direct vehicles tothe weighbridge, payment booth and unloading area(s).

At larger landfills, where internal roads should eitherbe permanent or have a substantial service period,roads should be sealed, particularly if on steep gradi-ents. Temporary access roads should be constructed toan all-weather standard.

If a special reception area is available to the public,particular care will be required in the design, layout andoperation of traffic control systems. Unloading areasshould provide, separately, for both small and largevehicles.

Site Facilities

Site Entrance Notification

Signs should be provided to ensure all users are madeaware of the following:

• access restrictions;

• days and hours of opening;

• acceptable (or prohibited) wastes;

• materials accepted for recycling;

• disposal charges;

• documentation that must accompany any wasteload;

• level of control and inspection of wastes to beundertaken;

• name and emergency contact number of the facilityoperator; and

• name of the facility owner.

Directional signage should be provided to assist smoothtraffic flow to the reception facilities, weighbridge,payment booth, recycling compound and unloadingareas, as appropriate.

All signs, should give information in a concise, easy-to-read and attractive manner.

Weighbridge

Accurate data on the quantity of waste disposed of inthe landfill is important for operational control, futuredevelopment of the site and long-term planning. Themost accurate way of obtaining the required data is toweigh incoming refuse.

A weighbridge provides the most equitable method forassessing charges to users, particularly commercialusers. It can also assist in determining in-place densi-ties of the filling area for landfill control purposes.

The importance of data for deriving waste quantitiesnow means that weighbridges may be justified even forlandfills for relatively small communities.

Charging Booth

A booth should be provided for the gathering of fees orcoupons and the recording of user data to enableinvoicing of frequent, large-volume users.

Important aspects to consider for the booth are:

• siting;


— cannot be avoided or bypassed;

— flat area to enable vehicles to stop;

— space for vehicle queue within the site;

— minimum disruption to traffic flow;

• security for the cash and the cashier; and

• accounting procedures.

Operational Facilities

The nature and extent of facilities related to the opera-tional needs of the landfill will, to some extent, dependon the size of the operation.

Facilities that would normally be required include:

• staff washroom (toilets and possibly showers);

• staff lunchroom;

• first-aid and emergency equipment; and

• fire-fighting equipment.

Other facilities, such as plant storage sheds and main-tenance facilities, may be required for large operations.

Services

Services including telephone, power, water supply andsewage disposal should normally be provided on thesite. Often, due to the remoteness of the landfill fromserviced urban development, water supply and sewagedisposal on the site will need to be self-contained.

Water should be available in adequate quantity for fire-fighting. Piped (domestic) supplies may be supple-mented for this purpose by making provision for waterto be pumped from on-site ponds.

Hazardous Waste Reception and StorageCompound

Consideration may need to be given to the receptionand storage of small quantities of hazardous materials(for example, used oil), particularly if there is no otherfacility for hazardous waste treatment or disposal withina reasonable distance.

Important features of a hazardous waste storage com-pound are:

• secure and lockable;

• bunded, sealed floor to contain spills;

• completely covered, including walls, but well ven-tilated; and

• good access for the handling of drums.

Temporary storage could also be provided for possiblyhazardous waste awaiting analysis and classificationbefore appropriate decisions can be made regardingdisposal.

Wheel Wash Facilities

Wheel wash facilities should be provided where soiltype will cause a major off-site nuisance, such astracking mud on to public roads. Typical problem soilsare clays and sensitive silts. Adequate internal roadingconstructed with good metal or seal can eliminate theneed for wheel wash facilities.

Wash water should be tested for contamination anddrained to sedimentation ponds prior to discharge. Ifcontaminated, wash water may need to be disposed ofto the leachate disposal system.

Fencing and GateLandfills should be fully fenced along all site bounda-ries to ensure the safety of the general public andprevent unauthorised entry and disposal.

Consideration should be given to the security of the siteoutside the hours of operation to prevent damage tobuildings and equipment and/or danger to unauthor-ised personnel.

LandscapingIt is desirable that the landfill should present an attrac-tive appearance to the passing public. Areas of the site,which are not screened by natural topography or exist-ing vegetation, should be surrounded by a tastefullydesigned fence or planted shelter-belt to screen opera-tions from the view of the passing public and anynearby residences. The establishment of a plantedshelter-belt requires early planning to allow for ad-equate growth before landfilling commences.

In some cases there could be advantages in contouringthe perimeter of the site to provide screening by earthmounds, and these could also be planted. Earth banksor bunds can also provide effective noise barriers.

Final Use and Final LandformKey aspects of landfill design are the determination ofthe final landform, the method of final reinstatementand final uses for the site.

The most common final uses for completed landfillsare:

• passive recreation (gardens, parks, golf courses);and


• controlled farming (agriculture or horticulture).

Integrating the issues of final use and final landformwill be significant in the determination of criticalparameters such as fill volume and potential lifespan.Factors to consider include:

• points of access;

• drainage patterns; and

• landfill cap requirements.

The end use options and final landform should becanvassed during the initial site selection, public con-sultation and resource consent processes. The plan ofthe final landform contours should be prepared as partof the design process prior to consent applications.

The final filling levels should be carefully controlled inaccordance with this plan.

Site CapacityHaving determined the final shape of the completedlandfill relative to the initial contours, the total volumeable to be contained on the site can be calculated.

An estimate of the compacted density of the refuse thatwill be achieved on the site, and of the compactedvolume of daily, intermediate and final cover requiredover the life of the site, must be made in order toestimate the total refuse tonnage that can be accommo-dated.

A target minimum in-situ density, excluding cover, of0.8 tonnes per cubic metre is readily achievable andshould be used in design for larger sites (>50,000 tpy).For smaller sites and sites without specialisedcompaction equipment a figure of between 0.6 and 0.8tonnes per cubic metre is more likely.

To make an allowance for daily cover, a waste to dailycover volume of between 4:1 and 5:1 can be expected.Intermediate and final cover volumes can be estimatedfrom their thickness.

The source of material for linings, daily refuse cover,intermediate cover and final capping materials must bedetermined. In many cases at least some of this materialmay be able to be excavated progressively from withinthe refuse fill area. This will increase the refuse volumeable to be disposed of in the site. The balance of thematerial not available on-site will have to be importedand an allowance for its volume must be made.

Assuming the refuse stream to the site can be quanti-fied (making due allowance for predicted changes overthe life of the facility), the likely lifespan of the facilitycan then be predicted.

The appropriate range of design densities for com-pacted refuse will depend on the compaction plantavailable, effort applied (as in earth compaction), andoperation methods adopted. For example, where arefuse landfill is operated by contract, a paymentsystem that rewards the achievement of high densitiesand penalises the non-achievement of target densities,is more likely to consistently achieve the waste densityadopted for design purposes.

Staging of Site DevelopmentMuch of New Zealand is subject to relatively highrainfall and short duration, high intensity rainfall events.These factors make it important that measures aretaken to reduce rainfall infiltration into the landfilledrefuse, and control leachate production.

It is essential to develop and operate the site in distinctstages, undertaking landfilling operations on as smalla part of the total site as possible at any one time. Areasnext required for filling should be prepared just prior tobeing used, and areas no longer being filled, or used fora period of time, should be capped, topsoiled andgrassed, and surface water drainage and erosion con-trol measures installed.

A development programme for the proposed landfillshould be prepared, using a series of plans that showthe areas and sequencing of the landfill operation.These should outline the measures required at eachstage for leachate collection, treatment and disposal,stormwater drainage and silt control, cover materialsource, and access roading, and how these will beprovided throughout the life of the site.

Figure 4.1 shows a typical operational plan for alandfill site.

Cells

One method of landfilling involves placing wasteswithin pre-bunded areas to form cells. This methodcan be used on medium-sized to large landfills, andencourages progressive filling and restoration.

Cells can vary in size depending on:

• rainfall;

• absorptive capacity of waste;

• filling rate; and

• number of vehicle movements.

Daily cells may be constructed within a larger cell iffilling rates are high. Using the cell method allowssurface water accumulating in prepared landfill areasto be treated as stormwater, prior to coming into


Coverstorage

area

Leachatetreatment

lagoon

Top-soilstore

Subsoilstore

PHASE 6 PHASE 4 PHASE 1

PHASE 5 PHASE 3 PHASE 2

Leachatecollection point

Surface watercollection point

Parkingarea

Wheel cleaningfacility

One-waytrafficsystem

Directionof filling

Sitecontroloffice

Waitingarea

Maintenanceworkshop

Sitecompound

Gate

Flow toexistingdrainagesystem

Fence

Settlement pond forsurface water with

dischargeto drain

Concrete road

Public Highway

Cut-off drain aroundperimeter of landfill

Figure 4.1: Typical operational plan for landfill site

(Figure 5.16B From UK Department of the Environment Waste Management Paper No. 26 (1986))

contact with refuse and also minimises leachate pro-duction. Cells constructed within the landfill should be

built from a suitably inert and free-draining material toavoid stratified layers within the landfill.


If the cell method of landfilling is used, the designbalance between lost landfill space versus cell sizeshould be considered. Cell walls should exceed refuseheight during filling, and hydraulic lift must be consid-ered in sites prone to varying groundwater tables.

Cell walls may be constructed in low permeabilitymaterial to retain leachate if this is consistent with thedesign of the leachate collection and removal system.It is important that cell wall construction is carried outwith suitable structural stability to ensure the contin-ued retention of waste and in such a way that the wallmay, if required, be removed when the adjoining cell isconstructed. Care should be taken to ensure that leachatebreakout does not occur through the wall.

4.4 Groundwater Managementand Control

GeneralGroundwater management is an important considera-tion in the design and operation of a landfill. Thegroundwater needs to be managed so that:

• the groundwater does not adversely affect thelandfill, in particular the liner system; and

• the normal flow of groundwater is not adverselyaffected by the landfill.

Site investigations should clearly determinegroundwater flows in the area of the site and themaximum range of groundwater levels.

Normally the landfill liner system should be locatedabove the groundwater table with an unsaturated zoneimmediately below the liner. Stringent management isrequired for groundwater seepages from either thesides or base of landfills located in excavations belowthe groundwater table. In such cases it is necessary torelieve hydrostatic pressures that may otherwise causeuplift forces on the landfill liner and hence potentialinstability or rupture.

The protection of groundwater from the impact oflandfill leachate is covered in Section 4.6.

Groundwater DrainageIn situations where the landfill is located below thewater table, an under drainage system should be pro-vided to intercept groundwater seepages and to controlgroundwater levels beneath the landfill area. A gravitydrainage system is preferred for all long-term require-ments.

Design of an under drainage system should consider

the following:

• pipes designed to allow inspection and mainte-nance and to carry the maximum probable flow;

• incorporation of specific drainage requirements toaccommodate discrete spring flows;

• careful selection of filter stone or filter fabric sizeto avoid potential clogging of drainage layers byfine materials; and

• protection of pipes to ensure risk of damage isnegligible.

In general, the designer will need to demonstrate byway of calculation that the proposed design is robust.

Drainage layers and pipes should be over-designed toallow for clogging and possible deterioration. In addi-tion, it is preferable to design the under drainagesystem to enable use of closed circuit television (CCTV)and remote control hydro-jetting equipment for in-spection and cleaning of pipework.

Groundwater drainage discharge flowrate and qualityshould be regularly monitored to detect any leachatecontamination. This is discussed in Section 6.4.

4.5 Surface Water andStormwater Management

GeneralSurface water and stormwater management are two ofthe most important aspects of successful landfill opera-tion. Stormwater control is a critical aspect of landfilldesign and generally cannot be successfully retrofit-ted. Surface water management is required to ensurethat:

• contaminated surface run-off from the active fillarea does not enter water courses;

• rainfall run-off from surrounding areas does notdrain into the landfill;

• surface water and stormwater does not generateexcessive quantities of leachate; and

• ponding and erosion on filled and capped landfillsurfaces is minimised.

Surface Water and Stormwater ControlThe surface water management objectives listed abovemay be achieved by the following control measures.

• Interception drains surrounding the active fill area


to prevent overland flow from entering the activefill area should be provided.

• Rainfall falling on the active fill area should becollected and managed as leachate via the leachatecollection, treatment and disposal system.

• Rainfall run-off from slopes outside and above thelandfill should be intercepted and diverted to wa-tercourses. These diversion drains/channels mayrequire invert protection to prevent scour and/orlining to prevent leakage into the landfill.

• Drainage channels or drains constructed on thecompleted landfill surface should be designed andconstructed to accommodate settlement, minimiseor eliminate erosion, and cope with localised de-sign storms.

• Completed fill areas and areas of intermediatecover should be contoured to direct stormwater intodrains leading away from the active filling area andworking face.

• Permanent or temporary access roads should bedesigned to prevent them acting as stormwaterchannels that may direct water into the landfill.

Surface Water DischargesWater discharged from any of the above sources tosurface water courses must be disposed in accordancewith the discharge permit(s), which may stipulate bothquality and quantity limits.

Any stormwater that has been diverted from the fillingsite is likely to carry a high silt load and should be heldin sedimentation ponds prior to discharge.

Sedimentation ponds should be developed prior todischarge of surface waters to natural stream or riverflows. The ponds and traps should be designed toensure easy maintenance and cleaning.

4.6 Leachate Generation andCharacteristics

Leachate CharacteristicsNumerous physiochemical and biological processesgovern the production and composition of landfillleachates. In general, the composition of leachate willbe a function of the types and age of waste deposited,the prevailing physiochemical conditions, and themicrobiology and water balance of the landfill.

Decomposition of the putrescible waste takes place bythe action of microbes. It occurs in three stages. In the

first stage, degradable waste is attacked by aerobicorganisms, resulting in production of organic com-pounds, carbon dioxide and water. Heat is generatedand the aerobic organisms multiply.

The second stage commences when all the oxygen isconsumed or displaced by carbon dioxide. Aerobicorganisms, which thrived when oxygen was available,die off. The degradation process is then taken over byfacultative organisms that can thrive in either thepresence or absence of oxygen. These organisms canbreak down the large organic molecules present infood, paper and similar waste into more simple com-pounds such as hydrogen, ammonia, water, carbondioxide and organic acids. During this stage carbondioxide concentration can reach a maximum of 90percent, although concentrations of about 50 percentare more usual.

In the third and final stage (the anaerobic, ormethanogenic phase) methane-forming organismsmultiply and break down organic acids to form meth-ane gas and other products. The water soluble degra-dation products from these biological processes, to-gether with other soluble components in the waste, arepresent in leachate. In addition, pH changes and acidformation may mobilise metals and increase theircontent in the leachate. Table 4.1 shows the changes inleachate composition that occur as a landfill proceedsthrough the various phases of decomposition.

The main components in the leachate from landfillsites may be conveniently grouped into four classes asfollows:

• Major elements such as calcium, magnesium, iron,sodium, ammonia, carbonate, sulphate and chlo-ride.

• Trace metals such as manganese, chromium, nickel,lead and cadmium.

• A wide variety of organic compounds, which areusually measured as total organic carbon (TOC) orchemical oxygen demand (COD). Individual or-ganic species such as phenol can also be of concern.

• Microbiological components.

Household waste is reasonably consistent in composi-tion over all landfill sites, as is the resulting leachate.Leachate composition at sites accepting predominantlyindustrial waste is much more variable.

The composition of leachates is generally in the formof a clear liquid which turns black and odorous uponcontact with air. The rate of generation of leachate isclosely linked to the water balance within the landfill,but even in very dry landfills there is enough moistureto generate small quantities of leachate.


In order to determine leachate composition, leachateanalysis needs to be undertaken at regular intervals.

It is important to note that leachate monitored at acollection point receiving leachate from different areasof a landfill can be a mixture of old and new, weak andstrong leachate. In addition, leachate concentrationscan be lower than those presented above for themethanogenic phase for very stable landfills or thosewith a high degree of water infiltration.

Leachate Characteristics at NewZealand LandfillsThe leachate characteristics for a number of NewZealand landfills are listed in Table 4.2.

This data reflects the differences in the monitoringconditions set for each landfill. For example, at theHorotiu Landfill, leachate from 14 cells is required tobe monitored. The low concentrations given for Horotiuare from a cell closed for more than 10 years and the

high concentrations are from a currently operating cell.At the Rosedale Rd Landfill, the high leachate concen-trations are from a currently operating cell and the lowconcentrations are composite leachate from the wholesite prior to sewer discharge. The highs and lows atRedruth, Redvale and Southern Landfills represent themaximum and minimum levels in the range of resultsobtained for leachate collected from the same locationover time.

Factors Affecting Leachate GenerationThe factors that influence leachate generation at landfillsinclude:

• Climate: Climate at the site significantly influ-ences the leachate generation rate. All other factorsbeing equal, a site located in an area of highprecipitation can be expected to generate moreleachate.

• Topography: Topography affects the site’s runoff

Parameters with differences between aceticand methanogenic phase

Parameters for which no differences betweenphases could be observed

Acetic phase Average Range Average Range

PH 6.1 4.5-7.5 Cl (mg/l) 2100 100-5000

BOD5 (mg/l) 13000 4000-40000 Na (mg/l) 1350 50-4000

COD (mg/l) 22000 6000-60000 K (mg/l) 1100 10-2500

BOD5 /COD 0.58 -- Alkalinity (mg CaCO3/l) 6700 300-11500

SO4 (mg/l) 500 70-1750 NH4 (mg N/l) 750 30-3000

Ca (mg/l) 1200 10-2500 OrgN (mg N/l) 600 10-4250

Mg (mg/l) 470 50-1150 Total N (mg N/l) 1250 50-5000

Fe (mg/l) 780 20-2100 NO3 (mg N/l) 3 0.1-50

Mn (mg/l) 25 0.3-65 NO2 (mg N/l) 0.5 0-25

Zn (mg/l) 5 0.1-120 Total P (mg P.l) 6 0.1-30

AOX (ug/Cl/l)* 2000 320-3500

Methanogenic phase As (ug/l) 160 5-1600

pH 8 7.5-9 Cd (ug/l) 6 .5-140

BOD5 (mg/l) 180 20-550 Co (ug/l) 55 4-950

COD (mg/l) 3000 500-4500 Ni (ug/l) 200 20-2050

BOD5 /COD 0.06 -- Pb (ug/l) 90 8-1020

SO4 (mg/l) 80 10-420 Cr (ug/l) 300 30-1600

Ca (mg/l) 60 20-600 Cu (ug/l) 80 4-1400

Mg (mg/l) 180 40-350 Hg (ug/l) 10 0.2-50

Fe (mg/l) 15 3-280

Mn (mg/l) 0.7 0.03-45 * adsorbable organic halogen

Zn (mg/l) 0.6 0.03-4

Table 4.1: Changes in leachate composition in different stages of a landfill

(Source: Ehrig, H. J., “Water and Element Balances of Landfills” in Lecture Notes in

Earth Sciences: The Landfill, 1989)


Tab

le 4

.2:

Lea

chat

e ch

arac

teri

stic

s at

sel

ecte

d N

ew Z

eala

nd

lan

dfi

lls

Hor

otiu

19

99

1R

ed

vale

19

99

2R

ed

ruth

19

99

3Y

ork

Val

ley

19

98

4

Om

aru

nu

i

19

98

5S

ou

the

rn

19

98

-99

6R

osed

ale

Rd

19

98

7G

ree

nm

ou

nt

19

98

7

Pa

ram

ete

ru

nits

low

hig

hlo

wh

igh

low

hig

hlo

wh

igh

low

hig

hA

lkal

inity

mg

/l2

64

68

20

**

12

00

38

00

18

60

35

00

**

12

60

47

23

*A

lum

iniu

mm

g/l

0.0

46

4.1

0.1

63

.17

0.0

57

.9*

0.0

60

.01

91

90

**

*A

mm

onia

cal

nitr

ogen

mg

/l6

7.1

14

40

50

28

50

.13

40

02

90

42

83

.44

71

78

.47

66

68

4A

rsen

icm

g/l

0.0

06

0.1

80

.00

80

.07

0.0

04

0.1

70

.14

0.0

19

0.0

13

0.0

55

0.0

07

30

.08

45

0.1

91

Bo

ron

mg

/l0

.54

19

3.4

20

.11

.15

.87

.21

00

.61

1.1

2.1

7.9

8.0

6B

iolo

gica

l ox

ygen

de

ma

nd

mg

/l1

41

66

50

38

67

14

>2

20

53

01

00

12

40

<2

32

20

23

0

Ca

dm

ium

mg

/l<

0.0

01

<0

.00

10

.00

04

0.0

1<

0.0

06

<0

.05

0.0

03

0.0

00

80

.00

03

0.0

01

<0

.00

5<

0.0

05

<0

.00

5C

alci

umm

g/l

85

38

06

46

20

36

37

0*

95

**

69

86

92

.5C

hlor

ide

mg

/l7

4.9

14

50

45

75

86

90

73

00

41

02

58

41

30

28

32

94

10

24

86

7C

hro

miu

mm

g/l

0.0

12

0.1

20

.03

50

.4<

0.0

50

.11

0.0

80

.10

.00

50

.16

0.0

15

0.2

18

0.1

3C

hem

ical

oxy

gen

de

ma

nd

mg

/l2

13

19

50

84

50

90

**

12

00

12

60

10

91

36

**

10

40

Con

duct

ivity

S

/cm

19

05

15

65

02

30

02

43

00

30

82

54

6*

11

45

01

51

30

27

90

03

28

01

13

10

92

90

Dis

solv

ed r

eact

ive

ph

osp

ho

rus

mg

/l0

.01

26

.54

0.0

30

.32

**

**

0.1

0.1

0.0

4*

*

Iro

nm

g/l

3.7

32

1.6

19

83

.51

41

78

21

52

20

8.2

7.5

72

.87

Le

ad

mg

/l0

.00

10

.01

40

.00

70

.17

0.0

89

*0

.02

<0

.01

0.0

01

0.4

2<

0.0

2<

0.0

20

.09

Ma

gn

esi

um

mg

/l2

02

00

81

17

51

06

90

*1

40

**

36

.58

28

7.5

Ma

ng

an

ese

mg

/l0

.67

40

.45

5.5

0.4

95

.24

.60

.55

10

12

**

0.8

94

Nic

kel

mg

/l0

.01

20

.14

0.0

51

9.5

0.0

19

0.0

37

0.0

30

.35

0.0

01

0.1

40

.03

40

.09

30

.12

4N

itrat

e ni

trog

enm

g/l

0.0

03

0.1

20

.01

1.1

<0

.01

0.0

17

0.0

62

.10

.01

0.0

9*

**

pH

pH U

nits

5.9

7.4

6.3

8.2

6.5

7.7

*8

.56

.26

.5*

*7

.5P

ota

ssiu

mm

g/l

80

74

02

04

35

87

.23

80

15

07

20

**

13

1.2

54

03

06

Sili

cam

g/l

12

36

**

**

**

**

**

*S

od

ium

mg

/l5

79

70

50

07

55

20

42

50

29

01

36

0*

*2

22

81

27

80

Su

lph

ate

mg

/l1

49

97

45

22

78

03

22

3*

*1

8.5

53

.18

4.7

Sus

pend

ed s

olid

sm

g/l

**

18

60

48

50

11

0*

**

**

**

Tot

al K

jeld

hal

nitr

ogen

mg

/l7

0.5

13

70

**

**

**

**

18

67

93

*T

otal

oga

nic

carb

onm

g/l

87

.38

22

**

17

.26

40

*3

78

**

**

*T

otal

har

dnes

sm

g/l

**

22

70

62

71

50

37

60

**

**

17

2.5

21

52

31

.3T

otal

phe

nols

mg

/l*

**

**

**

0. 0

04

6*

**

**

Vol

atile

aci

dsm

g/l

**

**

<4

67

2*

0.3

2*

**

**

Zin

c

mg

/l0

.01

50

.80

.13

24

.20

.11

1.6

0.6

0.0

09

1.1

0.1

45

0.1

58

0.2

33

Tot

al V

OC

**m

g/l

0.2

20

.87

0.0

03

23

.40

.10

0.1

5*

<LO

D*

**

*0

.11

Tot

al S

VO

C**

mg

/l0

.06

0.1

50

.00

06

8.7

<LO

D<

LOD

*<

LOD

**

**

0.0

04

Met

als

anal

yses

are

for t

otal

met

als

*

not r

epor

ted

*

* ex

clud

ing

LOD

val

ues

(LO

D =

Lim

it of

Det

ectio

n)S

ourc

e: 1

- H

amilt

on C

ity C

ounc

il, 2

- W

aste

Man

agem

ent N

Z L

td,

3 -

Tim

aru

Dis

tric

t Cou

ncil,

4 -

Nel

son

City

Cou

ncil,

5 -

Has

tings

Dis

tric

t Cou

ncil,

6 -

Wel

lingt

on C

ity C

ounc

il ,

7 -

Env

irow

aste

Ser

vice

s Lt

d


pattern and the amount of water entering and leav-ing the site. Landfills should be designed to limitleachate generation from areas peripheral to the siteby constructing perimeter stormwater drainagesystems to divert surface water “run-on” awayfrom the site and by constructing the landfill coverto promote runoff and reduce infiltration. All areasof a landfill should maintain at least two percentgrade over the waste at all times to prevent pondingof surface water.

• Landfill Cover: Landfill cover at the site affectsthe amount of water percolating into the landfill toform leachate. In general, as the permeability of thesoil used for final cover increases, leachate produc-tion rates increase.

• Vegetation: Vegetation plays an integral part inleachate control. It limits infiltration by intercept-ing precipitation directly (thereby improving evapo-ration from the surface) and by taking up soilmoisture and transpiring it back to the atmosphere.A landfill with poor vegetative cover may experi-ence erosion that cuts gullies through the cover soiland allows precipitation to flow directly into thelandfilled waste.

• Type of waste: The type of waste, the water content

of the waste and the form that it is in (bulk, shred-ded, etc.) affect both the composition and quantityof leachate. Wetter wastes, for example, will gen-erate more leachate.

Predicting Leachate Production RatesSound landfill design requires calculation of expectedleachate production. The amount of leachate gener-ated will affect operating costs if leachate collectionand treatment are provided. The amount of leachateformed also affects the potential for liner leakage andhence the potential for groundwater contamination. Italso affects the cost of post-closure care.

Predicting leachate generation quantities requires wa-ter balance calculations. The issues to consider indeveloping a site water balance are illustrated in Figure4.2. A water balance equation is presented below.

L0 = P – SRO – ET – DS

where

L0 = leachate production (m3/year)

P = precipitation (m3/year)

SRO = surface runoff (m3/year)

Watertable

Surface waterinfiltration

Sub-surfacewater infiltration

Final coverSurface water

run-off

Groundwater flow

Migration of leachate in groundwater

Leachate production

Level ofleachatewithinlandfill

Infiltration (Landfill)Waste uptake

of liquid

Precipitation

Water losswith gas release

Evapo-tra

nspira

tion

Figure 4.2 Landfill water balance issues

(Figure 3.3 from UK Department of the Environment Waste Management Paper No. 26 (1986))


ET = evapotranspiration (m3/year)

DS = change in leachate storage of the waste(m3/year)

The equation estimates the amount of water from rainor melting snow that will percolate through the landfillcover. Over time, the volume of percolating water willnearly equal the volume of leachate produced. Theremay be a lag between the time percolating water entersthe fill material and the time leachate emanates con-tinuously from the base of the fill. During this lagperiod the landfilled wastes increase in moisture con-tent until their field capacity is reached (field capacityis defined as the moisture content of the waste abovewhich downward flow of moisture will occur under theinfluence of gravity). Some leachate will be generatedintermittently (almost immediately in wet climates),because of water channelling through the wastes.However, once field capacity is achieved, leachateproduction should be more consistent.

The USEPA, in co-operation with the Army Corps ofEngineers Waterways Experiment Laboratory, has pre-pared a computer program, Hydrologic Evaluation ofLandfill Performance (HELP), to calculate the waterbalance of landfills. The HELP model version 3.0 hasweather records in data files and a weather generatorprogram to generate site-specific precipitation, air tem-perature and solar radiation data and offers options forpredicting leachate generation under many combina-tions of cover conditions.

The accuracy of HELP model predictions can be aidedby calibrating the model using actual field measure-ments of leachate generation at the landfill, or at otherlandfills in areas with a similar climate.

4.7 Leachate Retention andLiner SystemsBoth new landfills and lateral extensions of existinglandfills need to provide an appropriate level of reten-tion to protect the environment from the adverse ef-fects of leachate entering the aquifer system and sur-face waters. This would generally comprise:

• a leachate retention (or liner) system; and

• a leachate collection system.

At some sites, significant retention and attenuation canpotentially be provided by the underlying geology ofthe site, which may be able to act as a component of theliner system. At others, it will be necessary to rely ona well-engineered liner system over the entire base areaof the landfill for both retention and attenuation.

These guidelines, while recognising the statutory re-quirements for site-specific, effects-based design, alsoincorporate designs shown to provide a suitable levelof leachate retention at sites with a good level of naturalretention, selected in accordance with the site selectioncriteria in Chapter 3.

In preparing a leachate retention system design, a site-specific assessment of effects on the environment mustbe prepared to characterise the site and local environ-ment, identify environmental receptors and evaluatethe potential risks due to the landfill. This assessmentwill need to address:

• geology;

• hydrogeology;

• surface hydrology;

• stability; and

• environmentally sensitive areas.

In order to obtain sufficient information to assessactual and potential effects that could result from theuse of a design, specific investigations and studiesshould include:

• sufficient surface and subsurface investigations, bymapping, test pitting, drilling and monitoring to;

— develop geological cross-sections for materialsbeneath the site

— determine depth to water table and seasonalwater table fluctuations

— confirm the existence of groundwater divides

— measure hydraulic conductivities of materialsbeneath the site

— determine rate and direction of groundwaterflow, both vertical and horizontal

— identify potential preferential flowpaths forleachate and groundwater movement

— determine the dispersion characteristics of theaquifer

— locate aquifer recharge and discharge areas,seeps and springs

— determine baseline groundwater and surfacewater quality

— determine distance to and sensitivity ofgroundwater and surface water receptors orusers


— determine stability of materials underlying thelandfill site

• an assessment of likely quantity and quality ofleachate produced;

• an assessment of potential effects of failure ofleachate retention and collection systems; and

• an initial evaluation of potential contingency meas-ures to remediate the effects of retention systemfailure.

It is important to note that an engineered liner systemis not a perfectly impermeable barrier, and over time itwill allow relatively minor amounts of leachate into theunderlying soil and groundwater system. The linerneeds to be designed to ensure that the quantity ofleachate leakage and its concentration do not pose arisk to the environment. Design needs to take intoaccount the combination of liner hydraulic and chemi-cal diffusion and attenuation performance.

Leachate discharges from a landfill will potentially

occur over a period of time in excess of 30-50 yearsfollowing closure, with the leachate varying in strengthover time. It is difficult to predict the rate and quantityof leachate discharges, both over time and in responseto various events that could result in liner failure, andthe likely effects of these discharges. Therefore, adegree of redundancy is required in any liner design.

The following three liner designs, illustrated in Figure4.3, are recommended, as they have been shown toprovide a suitable level of protection to the receivingenvironment, for a landfill sited in accordance withthese guidelines.

(a)A single liner comprising 900 mm of clay or otherlow permeability soils compacted in layers a maxi-mum of 150 mm thick, to achieve a coefficient ofpermeability not exceeding 1 x 10-9 m/sec;

(b) A composite liner comprising a synthetic flexiblemembrane, 1.5 mm thick, overlying 600 mm ofclay with a coefficient of permeability not exceed-ing 1 x 10-9 m/sec;

900 mm

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaDrainage Layer

Perforated leachatecollection pipe

300 mm

Permeability < 1 x 10-9 m/s

Soil Subgrade

CompactedClayLiner

(a) Compacted clay liner

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaDrainage Layer


300 mm

Soil Subgrade

600 mm

CompactedClayLiner


1.5 mm syntheticflexible membrane

(b) Composite liner 1aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaDrainage Layer


300 mm

Soil Subgrade

600 mm

CompactedClayLiner


1.5 mm syntheticflexible membrane

Geosyntheticclay liner

(c) Composite liner 2

Figure 4.3 Recommended liner designs


(c) A composite liner comprising a synthetic flexiblemembrane 1.5 mm thick, overlying a geosyntheticclay liner (GCL), a minimum of 5 mm thick, witha coefficient of permeability not exceeding1 x 10-11 m/s, overlying a 600 mm thick compactedsub-base layer with a coefficient of permeabilitynot exceeding 1 x 10-8 m/s.

However, other designs could be suitable at some sites,after taking into account one or more of the followingfactors:

• landfill size;

• favourable geological and natural containment char-acteristics;

• unfavourable geological or hydrogeological char-acteristics; and/or

• proximity to, and sensitivity of, surrounding envi-ronments.

In considering alternative design requirements a quan-titative evaluation of retention system leakage and aquantitative assessment of effects on the receivingenvironment, including a quantitative assessment ofleachate migration and attenuation should be under-taken. This is likely to require significantly moreinvestigation and consent documentation than wouldbe necessary for the recommended designs, and in-clude:

• an assessment of the quantity of leachate leakagethrough the retention system, by both advectionand diffusion;

• leachate attenuation tests on materials underlyingthe site, using leachate similar to that expected atthe site;

• an assessment of likely leachate concentration ingroundwater at the site boundary or receiving envi-ronment; and

• an assessment of the effects of leachate contamina-tion on the receptor environment(s).

Where groundwater resources, with existing or poten-tial users, exist within 1000 metres of the landfill, thena risk analysis should be undertaken to confirm theadequacy of design.

Where the containment is based on natural site charac-teristics, an engineered barrier layer comprising one ofthe following should be used to reduce the potential forleakage due to inconsistencies in the natural site mate-rials:

• re-compaction of site soils to achieve a minimum

300 mm thick layer of demonstrated permeabilityof < 1 x 10-9 m/s, suitably protected from damageor desiccation; and

• an FML barrier, suitably protected from damage,over prepared in-situ low permeability soils.

The permeability of less than 1 x 10-9 m/s, recom-mended for the clay liner component of the first twodesigns, is aimed at ensuring that overall installed linerpermeability is not great enough to result in significantleakage, when scale, construction and post-construc-tion effects are allowed for. Permeability of linermaterials should be determined using pressure perme-ability methods (such as in a triaxial cell) and usingNew Zealand heavy compaction to simulate fieldcompaction of liner materials.

In all cases the emphasis must be on adequately dem-onstrating that the design will avoid potential adverseeffects and not result in long-term environmental deg-radation.

It should be noted that, due to the long-term potentialfor discharges from landfills, a lack of monitored orobserved adverse effects from an existing landfill siteis not in itself sufficient justification for a lateralexpansion using past design practices, without addi-tional investigations on areas proposed for expansion.The potential for cumulative effects from old and newareas of a site also needs to be considered with respectto lateral expansions.

Liner Construction IssuesLow permeability soils are often used for the construc-tion of landfill liners and, where they are available in-situ, they provide a cost-effective solution. They areoften used in conjunction with synthetic flexible mem-branes.

The design and construction of an engineered linermust be undertaken with an extensive quality assur-ance and quality control (QA/QC) programme, com-plemented by a well-defined materials testing pro-gramme.

Permeability specifications for clay liners are based onin-situ field permeability measurements.

In-situ testing of the permeability of the installed lineris not straightforward. Therefore, proof testing is bestundertaken by monitoring dry density and water con-tent of the installed liner and correlating this data to thelaboratory-measured permeability data obtained bytesting the clay compacted at various water contentsalong the compaction curve.

Soil liner material may originate at the site or be hauled


from a nearby borrow area. Soil additives, such asbentonite (montmorillonitic clay), may also be intro-duced to decrease the hydraulic conductivity of theliner material.

It should be noted that certain organic solvents inleachate can shrink the thickness of compacted clays.Consequently, the permeability of compacted claymay increase for certain leachates.

The joining or seaming of synthetic flexible mem-branes is critical as the seams are the most likely sourceof failure. Under the site-specific QA/QC plan, thejoints or seams should be tested for any potentialdefects.

The strength and stability of basement materials mustbe adequate to ensure the integrity of the liner for aslong as is required to ensure protection of the environ-ment.

Liner stability against slope failure also needs to beconsidered, along with construction practicalities, par-ticularly at the boundaries of segmented constructionphases for large landfills.

Penetrations and appurtenances need special care in allliner systems to ensure no leakage path is created.These should be avoided if at all possible.

Section 4.13 addresses QA/QC tests and testing fre-quencies for liner construction.

4.8 Leachate Collection andRemoval SystemsThe leachate collection and removal system is placedat the base of the landfill above the retention system.The functions of the leachate collection and removalsystem are:

• to remove leachate for treatment, disposal, and/orrecirculation into the landfill; and

• to control the head of leachate on the liner systemto minimise the quantity of leachate leakage.

The design and effectiveness of a leachate collectionand removal system is site-specific and depends on thedesign of the liner and the leachate collection pipes.General shape of the site, phase shapes, and overallslope and topography affect the layouts of the liner andpipe network systems.

A typical leachate collection and removal system shouldinclude the following components:

• a high-permeability drainage layer constructed of

either natural granular materials (sands and grav-els) or a synthetic drainage material (Geonet). Thedrainage layer is generally placed directly on theliner;

• perforated leachate collection pipes and/or boulderdrains within the high-permeability drainage layerto collect the leachate and carry it rapidly to acollection sump;

• sump(s) at low points within the system from whereleachate can be collected; and

• graded filter layers, as appropriate, over the high-permeability drainage layer and collection pipesand/or boulder drains to prevent physical cloggingof the material.

The design and construction of the collection systemneeds to be undertaken with great care to ensure that thesystem remains operable throughout the life and after-care period of the landfill. Failure of a componentcould render the whole system useless.

The collection system should be designed to ensurethat a minimum depth of leachate is retained over thelandfill liner. This depth can be calculated by takinginto account the quantity of leachate likely to beproduced, bottom slope, pipe spacing and drainagelayer hydraulic conductivity, by using the HELP model(referred to in Section 4.6), or using analytical equa-tions proposed by Giroud and Houlihan in the paperDesign of Leachate Collection Layers (1995). Thetarget maximum depth for leachate on the liner shouldnot exceed 300 millimetres.

The gradient of the collection system needs to beadequate to ensure that the leachate readily drains tothe collection sumps. A minimum gradient of 1 in 50(2 percent) is recommended.

Reliance on small diameter perforated pipes should beavoided to prevent clogging of the perforations. Aminimum diameter of 150 mm is recommended.

Piping design needs to consider not only hydrauliccapacity, but also structural strength to accommodatethe weight of refuse above them. Spacing should bedetermined by the maximum leachate head allowed inthe design.

Allowance should be made for additional lining pro-tection beneath leachate collection pipes and sumps asthese areas have the potential for the highest leachateheads.

4.9 Leachate RecirculationLeachate recirculation has been shown to offer signifi-


cant benefits in reducing the strength of leachate interms of BOD and some metal ion concentrations.

The other benefits of leachate recirculation include:

• increase in the rate of waste stabilisation and settle-ment;

• increase in the quantity and quality of methane gasproduction; and

• provision of a viable on-site leachate managementmethod.

Generally, leachate should only be recirculated in thelandfills that are designed and equipped with a linerand leachate collection system constructed for a target300 mm depth of leachate over the liner.

Leachate recirculation systems require design to ad-dress potential problems associated with:

• leachate seepages and breakout on side slopes;

• increase in leachate head on the base of the landfill;

• initial increase in leachate strength;

• increase in landfill gas production and odour nui-sance;

• differential settlement; and

• stability of the waste mass.

Leachate recirculation should be provided for as soonas it is practicable to do so. Leachate produced frommore recent areas of the landfill should be collectedand discharged to areas containing aged refuse. Dis-charge is generally via a subsoil perforated pipe over alength of trench constructed just below the surface ofthe fill and remote from the leachate collection system,to maximise the percolation distance. Recirculatedleachate should not be sprayed onto the surface of oldareas of the landfill as problems of contaminatedsurface runoff and odour could result.

Rates of recirculation should be carefully monitoredand controlled to ensure that areas of refuse do notbecome saturated, as this could result in surface out-breaks, and could potentially jeopardise the slope sta-bility of the landfill. Rates and areas of recirculationshould be carefully chosen and will invariably requireseasonal adjustment to maintain optimum landfill per-formance.

4.10 Leachate Treatment andDisposalLeachate collected from landfill drainage systems needs

to be pre-treated and/or disposed of carefully, to reducethe risk of pollution.

Methods of leachate treatment and/or disposal include:

• discharge to a community sewerage system, with orwithout pre-treatment;

• discharge to land by spray or subsurface irrigation,with or without pre-treatment;

• discharge to natural water following treatment;

• treatment by recirculation within the landfill; and

• evaporation using heat generated from the combus-tion of landfill gas.

At present, the dominant method of disposal is thedischarge of leachate to a sewer, land or watercourse.

Where discharge is to a sewer, treatment of the leachatetakes place at the sewage treatment plant. Where vol-umes of leachate generated are low, tankering leachateto a sewage plant may be the most appropriate methodof disposal. Since leachate strengths are significantlygreater than normal municipal waste waters, care shallbe taken to avoid overloading the sewage treatmentplant. Studies have shown that sewage treatment plantoperation has been disrupted when leachate exceeds 2percent of the hydraulic loading.

A further option for off-site treatment is at a specialisedhazardous or toxic waste centre, where leachate fromlandfills in the region is accepted.

The volume and strength of leachate produced atlandfill sites is subject to large seasonal variations.Wide fluctuations in flow and concentration can beminimised by balancing leachate flow, either by stor-age within already deposited waste or by using alagoon, so reducing the required treatment capacity byremoving the peak loadings. However, concentrationsof components in leachate also change with its age.Treatment strategies must therefore adapt to changes inleachate volumes and strengths both during the fillingstage of the landfill and after its completion.

Leachate, particularly that from recently placed wastes,contains high concentrations of readily biodegradablematerial (principally organic acids) which is amenableto biological treatment. Leachate from wastes thathave been deposited for a longer time is generallylower in organic content, less readily biodegradableand may contain relatively high concentrations ofammonia or iron. Thus, leachate from aged waste mayrequire a combination of processes for effective treat-ment.

The method and degree of leachate treatment neces-


sary will be site-specific and dependent on the type ofwaste deposited, any expected variation in flow, strengthof toxic components and the nature of the receivingenvironment.

On-site Treatment TechnologiesTechnologies for on-site treatment of leachates in-clude:

• biological anaerobic or aerobic systems;

• chemical oxidation and reduction;

• precipitation;

• air stripping; and

• carbon adsorption.

The selection of a treatment process should be based onleachate quality, laboratory evaluation studies and,where possible, on pilot-scale studies. Where noleachate data exist, such as at the design stage for a newlandfill, an alternative approach is required. In thissituation leachate quality may be predicted fromleachate generation calculations, experience at othersites, and leaching tests for typical industrial and otherwastes expected to be received.

Land Treatment and DisposalSpray irrigation, or subsurface irrigation, of treatedleachate is an effective disposal method where suitableland areas and soil types are available. Department ofHealth guidelines on waste irrigation recommend thatonly pre-treated effluent be irrigated. Subject to site-specific requirements, oxidation ponds with minimumdetention of 30 days or, alternatively, two-stage aer-ated lagoons with a minimum total detention of 10days, may be appropriate.

Spraying of treated leachate onto land can result in asignificant reduction in its volume, due toevapotranspiration. Additionally, as the leachate per-colates through vegetated soils, opportunities are pro-vided for microbial degradation of organic compo-nents, removal of inorganic ions by precipitation or ionexchange, and the possibility of rapid uptake by plantsof constituents such as nitrate (from soil bacteria oxi-dation of ammonia).

Intermittent spraying throughout each day will providemore effective evaporation than a single daily applica-tion. Transpiration by vegetation will account for asubstantial proportion of the total loss. The possibilityof spreading harmful pathogens by spraying leachateneeds to be considered, but evidence to date suggeststhat this is not a problem provided appropriately treated

leachate is applied and the operation is properly man-aged.

Little information is available on the long-term effectsof continual spraying of leachate onto land. The spray-ing of leachates containing metals or persistent organiccompounds is not recommended because of their accu-mulation in soils and plant material. In this respect,reference should be made to publications on the appli-cation of sewage sludge to land.

4.11 Landfill Gas Management

GeneralIn general terms, landfill gas will be produced in almostall landfills. Gas is produced as an end product ofbiological decomposition. Although mainly methaneand carbon dioxide, it may also contain other gases,including volatile organic compounds. Table 4.3 givesa typical composition of landfill gas. In the earlyaerobic decomposition phase, the gas is predominantlycarbon dioxide. In the later anaerobic decompositionphase, the gas has a relatively high methane content.Methane may be generated in commercial quantities.

Potential Problems Associated WithLandfill GasPotential problems as a result of landfill gas include:

• detrimental effects on soils and vegetation withinthe completed landfill and adjacent sites;

• risks to human health (on-site and off-site);

• risks of explosions or fires due to gas migrating andcollecting in confined spaces such as manholes andchambers and poorly ventilated areas of buildingson or adjacent to the site;

• odour nuisance;

• ignition of landfill gas upon release through cracksand fissures at the surface (methane fires are gener-ally not visible in daylight); and

• asphyxiation of personnel entering trenches, man-holes or buildings on or near the landfill site.

Landfill Gas ProductionThe rate of gas production can be controlled to a largeextent by the adoption of appropriate landfill manage-ment techniques. Site design may require that gasproduction be either encouraged or minimised, de-pending on whether or not the gas is to be utilised.Where accelerated stabilisation is an objective, a sub-stantially greater rate of gas production will result. The


rate of gas generation can be influenced by controllingconditions within the fill, particularly moisture, throughsuch measures as controlling the integrity of surfacecapping, recirculating leachate through the landfill, orirrigation.

Ensuring that the waste is well-chopped and com-pacted as it is placed will hasten the onset of theanaerobic phase of degradation for the more readilydegradable materials. Rapid filling of small areas ofthe site will shorten the aerobic degradation phase andtend to keep waste temperatures down.

Where large volumes of high BOD leachate are pro-duced and removed from the site without recirculation,the resultant loss of nutrients, on which gas productionrelies, will reduce the overall quantities of gas pro-duced.

Daily or intermediate cover and the use of low perme-ability materials in cell construction may result in thedevelopment of perched water tables and have effectson moisture movement, transmission of gases andbuffering of leachates. Such effects will be importantin terms of gas production, migration pathways andproposed methods of gas control. Even active gasextraction systems can further contribute to the gasproduction process by drawing moist saturated gasesthrough the body of the fill.

Landfill Gas ControlThe requirement for a landfill gas control system willdepend on:

• the quantity and rate of landfill gas production;

• the potential for odour nuisance to site neighbours;and

• potential risks associated with landfill gas migra-tion.

A landfill gas control system, if required, would gen-erally incorporate:

• a system to retain gas within the landfill site andprevent offsite migration;

• a landfill gas collection and utilisation or flaringsystem;

• a separate system for controlling gas migration atthe perimeter of the site that is capable of independ-ent operation from the collection system for gaswithin the waste body;

• gas monitoring boreholes/wells outside the wasteboundary;

To effectively design and operate a landfill gas controlsystem it is necessary to understand that two largelyindependent mechanisms for gas migration exist;

• gaseous diffusion (concentration gradient); and

• advection (pressure gradient).

In order to make the gas control system robust, it isusually necessary to have more than one level ofcontrol at any site. The levels of control must be sitespecific.

Migration Control and Monitoring

It is important to detect possible gas migration from thesite towards sensitive areas. Purpose-designed gasmonitoring boreholes should be installed between thesite and sensitive property boundaries and regularmonitoring should be undertaken. Landfill gas moni-toring is discussed in more detail in Section 6.7.

Component Percent

(dry volume basis)

Methane 45 - 60

Carbon Dioxide 40 - 60

Nitrogen 2 - 5

Oxygen 0.1 - 1.0

Sulphides, Disulphides, Mercaptans, etc. 0 - 1.0

Hydrogen 0 - 0.2

Carbon Monoxide 0 - 0.2

Trace Constituents 0.01 - 0.6

Table 4.3 : Typical constituents found In landfill gas

(Source: Trace Organic Constituents in Landfill Gas, Department Civil Engineering, University

of California, Davis, November, 1987)


Appropriate measures should be taken to adequatelycontrol the accumulation and migration of landfill gas.Migration control systems should primarily be estab-lished and concentrated around the perimeter of thelandfill if there is a risk of lateral migration towardsadjacent developed property. Control systems shouldbe progressively installed as filling is completed adja-cent to susceptible areas.

No single form of gas migration control may be ad-equate to protect sensitive adjacent property. Thus, inaddition to an on-site gas collection system, othermeasures, such as the use of low-permeability barriersbetween the site and the adjacent strata, may be neces-sary. Because of differences in the viscosity of liquidsand gas, clay and bentonite clay barriers are orders ofmagnitude less effective at restricting the flow of gasthan that of leachate. Hence the designer may need toconsider whether the proposed leachate retention liner/barrier is adequate for gas control or whether a higherspecification liner using a synthetic flexible membraneis required for gas control purposes.

Currently three types of systems are used, either indi-vidually or in combination, to control lateral migrationof landfill gas. These are:

• passive venting;

• physical barriers; and

• suction-driven landfill gas extraction.

Passive venting systems should only be used in landfillswhere the rate of gas generation is low (e.g. small orbiologically old sites).

Physical barriers range from stone-filled trenches tolow permeability constructions including combina-tions of flexible geomembranes, bentonite slurry wallsand piles and cut-off walls. To be fully effectiveagainst gas migration, clay barriers should incorporatea geomembrane. The performance of all physicalbarriers is improved when combined with a means ofgas removal (i.e. extraction using suction or passiveventing).

Examples of passive landfill gas venting systems areshown in Figures 4.4 and 4.5.

Design of passive venting systems needs to take ac-count of hazardous area classifications (NZS/AS 2430,Classification of Hazardous Areas) potential as odoursources and potential flammability at the dischargepoint.

Landfill gas extraction systems comprise up to fivemain components and rely on suction to extract landfillgas from the landfill. The five main components of thesystem are:

• gas wells or drains constructed in the landfill;

• associated pipe network and pumping mains;

• condensate traps for the removal of condensedliquid from the system;

• landfill gas extraction pumps (blowers); and

• landfill gas diffusers, flares or a utilisation plant.

Individual gas wells should be located to achieve anappropriate radius of influence for gas extraction, withdue regard to any possible end use restriction. Gaswells should be sited to avoid penetrating the liner andavoid coincidence with special waste burial locationsas identified by the special waste survey (disposallocation) records.

An example of a gas extraction well for use in activesystems is shown in Figure 4.6.

It may also be possible to collect gas using leachaterecirculation trenches.

Landfill Gas DisposalDisposal of gas from a collection system is a continu-ous process. Landfill gas should either be flared orotherwise used to provide an economic return in suchprocesses as electricity generation or leachate evapora-tion.

Cap/restoration layerBentonite/clay/concreteseal, approx. 2 to 3 m

Vent pipe1.5 m high

WASTES

Selectedno-finesaggregate

Perforated/slottedHDPE pipe or similarup to 225 mm diameter

Figure 4.4 Example of passive landfill gas

venting well

(Figure 8.2 from UK Department of the Environment

Waste Management Paper No 27 (1991 ))


Regardless of the end use of the gas, some provision forflaring should be made, particularly if migration is aconcern. Flaring might be necessary to deal withexcess gas flow and instances when the utilisationprocess is not operational.

Flare systems should be designed to ensure that the gasis completely burnt at the highest possible temperature.Enclosed flares will provide the best combustion, how-ever open, or candle, flares may be appropriate, de-pending on landfill size and location.

Energy recovery should always be considered in pref-erence to flaring as landfill gas utilisation, as besidesbeing environmentally beneficial, it helps offset thecosts of landfill gas control. Where there are localusers, direct use of the gas is more efficient thanelectricity generation.

4.12 Landfill Cover SystemsLandfill covers fall into three categories having differ-ent functions:

• daily cover to reduce:

— windblown litter;

— odour;

— vermin; and

— birds.

• intermediate cover to:

— minimise water ingress;

— complete cells; and

— provide fire protection.

• final cover to:

— control water ingress;

— reduce leachate generation;

— provide final contour;

— provide gas control;

— allow plant growth; and

— permit end use.

Landfill cover is addressed in more detail, with respectto landfill operations, in Section 5.10.

Daily CoverDaily cover typically consists of a minimum of 150mm thick earthen layer or an alternative material suchas:

• geosynthetic blankets;

• shredded green waste;

• sawdust;

• spray on foam;

• contaminated soil (that complies with waste ac-ceptance criteria);

• ash (that complies with waste acceptance criteria);

• stabilised sludge;

• paper pulp;

• composted material;

Gas vent

Top layer

Low-permeability layer

Vent layer

Waste

FML

Perforated pipe

Figure 4.5 Example of passive landfill gas venting system

(Figure 3-4 from USEPA Solid Waste Disposal Facility Criteria Technical Manual (1993))


Flow meterGas sampling

valve

Topworksprotection1

Landfill cap

Cement grout

Dry cement mix

Waste

Selectedaggregate

approx 1 m

3 - 5 munperforatedpipe2

Pipe clearance abovebase to allow forsettlement andwater table

Base oflandfill

Well diameter4

Perforatedwell casing3

1 Topworks may be suitably protected aboveground by a robust ventilated enclosure, or belowground in a manhole which does not compromisethe integrity of the cap

2 Exact length of unperforated pipe depends onwaste depth and presence of water/leachatetable

3 Approximately 10% of pipe area should beperforated, at least 100 mm diameter, UPVC,MDPE, HDPE or polypropylene

4 Overall diameter determined by extraction raterequired, established by static tests

Figure 4.6: Example of landfill gas extraction well

(Figure 8.3 from UK Department of the Environment Waste Management Paper No 27 (1991))

• small weave netting; and

• heavy duty reusable plastic sheets or tarpaulins.

Intermediate CoverIntermediate cover typically consists of a compactedsoil layer. The thickness and hydraulic conductivity ofthe layer depends on:

• type of soils available on-site;

• slope and topography of the top of the refuse;

• area of the cell; and

• duration between the proposed placement of thefinal cover and the intermediate cover.

Final CoverFinal cover design is largely dictated by site design andmanagement provisions with respect to enhanced deg-radation (i.e. leachate recirculation), landfill gas man-agement and the proposed end use for the site. Never-theless, the following is considered the minimum rec-ommended specification for a final cover system:

• a compacted earth layer at least 600 mm thick, witha maximum hydraulic conductivity of 10-7 m/s; and


600 mm

150 mm

600 mm

600 mm

300 mm

300 mm

300 mm

Vegetation layer

Infiltration layer - compacted soil(K 1 x 10-7 m/s)

Refuse

<

Refuse

Vegetation layer

Filter layer

Biotic barrier layer

Drainage layer

Compacted clay layer

Gas venting layer

FML

Figure 4.7: Examples of final cover designs

• topsoil at least 150 mm thick that is capable ofsustaining plant growth.

Examples of final cover designs are shown in Figure4.7.

Other issues that need to be considered in the designinclude the following:

• Surface gradients. These will be influenced by theproposed final use of the site, but should be gener-ous enough to ensure effective shedding of precipi-tation. A minimum gradient of 1V:20H is recom-mended to promote drainage of the top of thelandfill; a maximum gradient of 1V:3H is recom-mended to minimise erosion and post-closure careproblems.

• Effects of settlement, which may cause cracking orponding of water.

• Vegetation cover. For example, if the area is to begrassed then it is important to avoid creating a verylow permeability hard pan under a shallow layer oftopsoil. In such a case, the topsoil will tend tobecome soggy in winter and dry out in summer,inhibiting grass growth. A granular drainage layerimmediately above the cap may be required. Theadvice of a professional soil scientist is recom-mended.

Where leachate is recirculated to enhance waste degra-dation, the following issues need careful considerationwith respect to cover design:

• Gas production will be accelerated, and the poten-tial for adverse effects from odour, due to gasescape through the cover, increases.

• Settlement rates of the refuse are increased so thatthe bulk of settlement occurs much sooner.

• After-care requirements can potentially be reduced,and with them the potential for longer-term adverseenvironmental impact.

Where the final cover is designed to minimise theinfiltration of water into the waste and reduce the rateof degradation, a combination of a flexible membraneliner (1 mm to 1.5 mm thick), or geosynthetic clay linerand compacted soil layer, is typically used.

The following advantages and disadvantages need tobe considered.

Advantages

• The quantity of leachate generated at any one timeis much lower.

• Leachate treatment costs can be significantly less.

• If leachate is pumped at the rate it is generated,leachate heads on the liner can be significantlysmaller.

• Potential for landfill gas to escape from the cover isvery low, hence the potential for odour problemswill be small.

Disadvantages

• The breakdown of materials in the landfill will bevery slow.

• Leachate generation and gas production will con-tinue for longer periods.


Soil Component Test Name and Parameter(s) determined Test Method(ASTM or Equivalent)

Minimum TestingFrequency

Compacted clay linerMoisture Content ASTM D2216 1 per 2,000 m3 or each

change in material type

Sieve Analysis: Particle size distribution of fine and coarse aggregates. ASTM C136 1 per 5,000 m3 or eachchange in material type

Hydrometer Analysis: Particle size distribution of fine fraction of soils. ASTM D422 1 per 5,000 m3 or eachchange in material type

Atterberg Limits: Liquid limit and plastic limit ASTM D4318 1 per 5,000 m3 or eachchange in material type

Soil Classification: Classification of soil ASTM D2487 1 per 5,000 m3 or eachchange in material type

Standard or Modified Proctor: Moisture and density relationship ASTM D698/1557 1 per 5,000 m3 or eachchange in material type

Hydraulic Conductivity: Permeability of aggregates (exclude for beddinggravel) ASTM D2434 1 per 10,000 m3 or each


Granular leachatedrainage layer andbedding gravel

Sieve Analysis: Particle size distribution of fine and coarse aggregates

Soil Classification: Classification of soil

Hydraulic Conductivity: Permeability of aggregates (exclude for beddinggravel)

Carbonate Content: Insoluble residue in carbonate aggregates

ASTM C136

ASTM D2487

ASTM D2434

ASTM D3042

per source

1 per source

1 per source

1 per source

Structural fill and finalcover protective layer

Moisture Content


Atterberg Limits: Liquid limit and plastic limit


Standard or Modified Proctor: Moisture and density relationship

ASTM D2216

ASTM C136

ASTM D4318

ASTM D2487

ASTM D698/1557

1 per source

1 per source

1 per source

1 per source

Note: Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for Waste Containment Facilities”, EPA/600/R-93/182

Table 4.4: Soils - recommended tests and testing frequencies for material qualification

before construction

• Gas, leachate and settlement may become prob-lems decades after refuse placement, resulting in amajor after-care burden for the responsible authori-ties.

4.13 Construction QualityAssurance and ConstructionQuality ControlConstruction quality assurance (CQA) and construc-tion quality control (CQC) are critically importantfactors for overall performance of landfills. In orderfor the design to translate into a landfill that is protec-tive of human health and the environment, it has to beproperly constructed.

The manufacturing quality assurance (MQA) and manu-facturing quality control (MQC) are also equally im-portant for the geosynthetic materials used in landfillconstruction. The geosynthetic materials refer to fac-tory fabricated polymeric materials like geomembranesor flexible membrane liners, geotextiles, geosynthetic

clay liners, or geocomposites that include geonet andgeotextiles.

This section presents the recommended tests and test-ing frequencies for the soil and geosynthetic compo-nents of landfills. The testing frequencies presented inthis section should be used for guidance only. Actualtesting frequencies should be decided based on site-specific and project-specific factors such as variabilityof material, experience and qualification of the con-tractor and the supervising technician or engineer. Therecommended tests and testing frequencies for the soiland geosynthetic components of a landfill are pre-sented in Tables 4.4 to 4.10. For details on the rationalefor the tests and testing frequencies, the reader shouldrefer to the CQA and CQC Guidance Document by theUSEPA (1993).

The acceptance criteria, or the pass/fail decision for theconstructed soil components and installed geosyntheticcomponents, should be based on site-specific factorsand the maximum allowable risk to human health andthe surrounding environment from the landfill.




Subgrade for layingliner

Visual Observation:

Monitor unsuitable soil zones, uneven ground surface.

N/A As required

Compacted clay liner Moisture Content ASTM D2216 1 per 2,000 m3 or eachchange in material type







ASTM D2434 1 per 10,000 m3 or eachchange in material type

Granular LeachateDrainage Layer andBedding Gravel


Carbonate Content2: Insoluble residue in carbonate aggregates


ASTM C136

ASTM D3042

ASTM D2434

1 per 2,000 m3

1 per 2,000 m3

1 per 2,000 m3

Structural Fill andFinal Cover ProtectiveLayer

Sieve Analysis: Particle size distribution of fine and coarse aggregates.




ASTM C136

ASTM D4318

ASTM D2487

ASTM D698/1557

1 per 2,500 m3

1 per 2,500 m3

1 per 2,500 m3

1 per 4,000 m3

Note: Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for Waste Containment Facilities”, EPA/600/R-93/182.

Table 4.5: Soils — recommended tests and testing frequencies prior to installation



Compacted clay linerMoisture Content ASTM D2216 1 per 2,000 m3 or each








ASTM D2434 1 per 10,000 m3 or eachchange in material type

Granular leachatedrainage layer andbedding gravel




Carbonate Content: Insoluble residue in carbonate aggregates

ASTM C136

ASTM D2487

ASTM D2434

ASTM D3042

1 per source

1 per source

1 per source

1 per source

Structural fill and finalcover protective layer

Moisture Content





ASTM D2216

ASTM C136

ASTM D4318

ASTM D2487

ASTM D698/1557

1 per source

1 per source

1 per source

1 per source

1 per source

Note: Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for Waste Containment Facilities”, EPA/600/R-93/182.

Table 4.6: Soils — recommended tests and testing frequencies during construction


Test Name Test Method (ASTM orEquivalent)

Minimum Testing Frequency

Specific gravity ASTM D792 Method A 1 test per 10,000 m2

Thickness ASTM D751 1 test per 10,000 m2

Tensile strength at yield ASTM D638 1 test per 10,000 m2

Tensile strength at break ASTM D638 1 test per 10,000 m2

Elongation at yield ASTM D638 1 test per 10,000 m2

Elongation at break ASTM D638 1 test per 10,000 m2

Tear resistance ASTM D1004, Die C 1 test per 10,000 m2

Carbon black content ASTM D1603 1 test per 10,000 m2

Carbon dispersion ASTM D3015 1 test per 10,000 m2

Peel adhesion2 ASTM D44373 1 test every 150 m of seam length

Bonded seam strength2 ASTM D44374 1 test every 150 m of seam length

Vacuum testing2 - 100% of extrusion welded seams

Air testing2 - 100% of dual hot wedge or dual trackwelded seams

Notes:1. Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for Waste Containment

Facilities”, EPA/600/R-93/182.2. Applicable to geomembrane seams.3. For peel adhesion, seam separation shall not extend more than 10 per cent into the seam interface. Testing shall be discontinued

when the sample has visually yielded.4. For shear tests, the sheet shall yield before failure of the seam.5. Testing shall be carried out at a frequency of one per lot or at the above listed frequency, whichever is less.

Table 4.8: Geomembrane — recommended tests and testing frequencies



Mass per unit area ASTM D3776 1 test per 10,000 m2

Grab strength ASTM D4362 1 test per 10,000 m2

Mullen burst ASTM D3786 1 test per 10,000 m2

Puncture resistance ASTM D4833 1 test per 10,000 m2

Permeability (for filterapplication only) ASTM D4491 1 test per 10,000 m2

Apparent opening size (forfilter application only) ASTM D4751 1 test per 10,000 m2

Trapezoidal tear strength ASTM D4533 1 test per 10,000 m2

Thickness (for cushionapplication only) ASTM D1777 1 test per 10,000 m2

Notes:1. Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for Waste

Containment Facilities”, EPA/600/R-93/182.2. Testing should be carried out at a frequency of one per lot or at the above listed frequency, whichever is less.

Table 4.7: Geotextile — recommended tests and testing frequencies



Minimum Testing Frequency

Density ASTM D1505 1 test per 10,000 m2


Mass per Unit Area ASTM D3776 1 test per 10,000 m2

Hydraulic Conductivity ASTM D5084 1 test per 10,000 m2

Notes:

1. Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for WasteContainment Facilities”, EPA/600/R-93/182.

2. Testing shall be carried out at a frequency of one per lot or at the above listed frequency, whichever is less.

Table 4.9: Geosynthetic clay liner — recommended tests and testing frequencies



Geonet Component:

Carbon Black Content ASTM D1603 1 test per 10,000 m2

Density ASTM D1505 1 test per 10,000 m2


Geotextile Components:

Mullen burst strength ASTM D3786 1 test per 10,000 m2

Mass per unit area ASTM D3776 1 test per 10,000 m2

Apparent opening size (filterapplication only)

ASTM D4751 1 test per 10,000 m2

Hydraulic conductivity (filterapplication only)

ASTM D4491 1 test per 10,000 m2

Grab strength ASTM D4632 1 test per 10,000 m2

Trapezoid tear strength ASTM D4533 1 test per 10,000 m2

Puncture resistance ASTM D4833 1 test per 10,000 m2

Geocomposite:

Hydraulic transmissivity ASTM D4716 1 test per 10,000 m2

Peel strength ASTM F904 1 test per 10,000 m2

Notes:1. Source: USEPA (September 1993), “Technical Guidance Document, Quality Assurance and Quality Control for Waste Containment

Facilities”, EPA/600/R-93/182.2. Testing shall be carried out at a frequency of one per lot or at the above listed frequency, whichever is less.

Table 4.10: Geocomposite — recommended tests and testing frequencies

Landfill Operations • 51

Chapter 5Landfill Operations

5.1 IntroductionThe operational procedures employed at any landfillsite will have a significant bearing on its planneddevelopment, performance and potential effects on theenvironment, particularly effects on site neighbours.


• landfill management plan;

• staffing and training;

• health and safety;

• site access;

• waste acceptance and monitoring;

• roading;

• visual impacts;

• waste compaction;

• cover;

• nuisance control;

• fire prevention;

• water control;

• landfill gas management; and

• closure and aftercare.

5.2 Landfill Management PlanAll operations at a landfill should be undertaken inaccordance with a predetermined Landfill Manage-ment Plan. This plan should cover all aspects oflandfill operations, with detailed descriptions of:

• site management structure and responsibilities;

• design parameters;

• site development and filling sequence;

• daily operating procedures;

• types of equipment to be used on the site;

• monitoring requirements;

• emergency and contingency procedures;

• record keeping and reporting; and

• closure and aftercare of completed cells and thewhole landfill.

A recommended outline table of contents for a landfillmanagement plan is provided in Appendix 3.

The following sections provide details of the aspects oflandfill operations that should be addressed in thelandfill management plan and options for operatingprocedures.

5.3 Staffing and Training

StaffingThe level of staffing should be adequate for environ-mentally-responsible and safe management of thelandfill. Staffing requirements will vary as a functionof size, types of wastes, and diversity and complexityof site operations. Landfill operators should provideadequate staffing to ensure that during operating hoursall continuous tasks (including waste reception, andsecurity, compaction and covering) are completed inaccordance with the landfill management plan.

TrainingManagement and operating personnel must be familiarwith the landfill facilities (including environmentalprotection systems), operational practices, the status ofsite activities, and resource consent conditions, and alloperational staff should undertake training coursesrelevant to their particular duties. As a minimum, stafftraining should ensure that:

• staff who inspect or direct the placement of incom-ing wastes are capable of accurate data recording,and skilled at identifying wastes that are unaccept-able (these staff include supervisors, inspectors,equipment operators and weighbridge attendants);

• operators of compaction or earthworks equipmentare skilled at undertaking all tasks required of them;

• staff who undertake sampling or testing are famil-iar with required testing and sampling protocols;


• all staff are familiar with site safety practices andprocedures; and

• all staff are familiar with site emergency proce-dures.

All new employees should receive basic training aspart of their orientation and refresher training shouldbe performed on an annual basis. Documentation oftraining should be maintained in the site operatingrecord.

5.4 Health and SafetyLandfill operations must be performed in accordancewith the requirements of the Health and Safety inEmployment Act 1992, and a Health and Safety Planshould be prepared for each site setting out the proce-dures to satisfy each of the requirements of the Act.These include the following:

• The identification of hazards present on the site.Examples include traffic (including landfillcompaction equipment), landfill gas (LFG), sharp(injurious) refuse, steep and uneven terrain, andillegal disposal of hazardous waste.

• Hazard control, including elimination of the hazardwhere possible, isolation where elimination is notpracticable or not complete, or minimisation (in-cluding use of personal protective equipment) whereelimination and isolation are not practicable.

• The provision of information concerning identifiedhazards, control procedures, and possible emer-gency occurrences to employees engaged on thesite.

• Appropriate training and supervision of employeesat the site, including provision and use of safetyequipment.

• Development of emergency procedures, also knownas a contingency plan.

• Recording, reporting and investigation of acci-dents.

The Health and Safety Plan will apply to all employees,subcontractors and visitors at the site. Attention mustalso be paid to ensuring that any capital works contrac-tors engaged on the site are fully conversant with theHealth and Safety Plan. These contractors should bemade fully aware of potential hazards associated withthe landfill operations activities.

The Health and Safety Plan should be reviewed regu-larly to ensure that all hazards are identified andcontrolled, training and supervision are provided in a

satisfactory and timely manner, and accident and nearmiss reporting systems are operational.

5.5 Site AccessUnauthorised entry to landfills can lead to illegal wastedumping, exposures to landfill hazards, fires, and van-dalism of pollution control devices, as well as loss ofamenity. In order to control site access, the perimeterof the landfill site should be securely fenced and thegates locked outside normal operating hours. Closecontrol over the issue of keys to the landfill should bemaintained to ensure public health is adequately safe-guarded and the operational procedures are compliedwith at all times. All incoming vehicles should reportto the weighbridge or reception office before proceed-ing further to waste reception or working areas. Alllandfill sites should be sign-posted at each entrancewith the following information:

• landfill name;

• owner and operator;

• contact details for the owner and operator, includ-ing after-hours telephone contact for senior sitestaff;

• emergency telephone contacts;

• hours of operation;

• a general description of the types of wastes ac-cepted at the site;

• a generalised list of prohibited wastes; and

• the requirement for a waste acceptance agreementto be in place before the site is used for wastedisposal.

5.6 Waste Acceptance andMonitoring

Waste Acceptance CriteriaThe purpose of establishing waste acceptance criteria(WAC) is to ensure that all wastes being disposed inthe landfill are compatible with the operation of thelandfill and do not lead to immediate or longer-termadverse environmental effects. Waste acceptance cri-teria should be determined during the resource consentprocess, based on landfill siting and design of reten-tion, leachate collection and treatment/disposal sys-tems.

Development of waste acceptance criteria should take


into account the need to protect landfill processes, thepotential for discharge of hazardous substances to theenvironment, and the need to minimise the risks asso-ciated with hazardous substances, such as effects onhuman health and safety.

The codisposal, or joint disposal, of untreated hazard-ous waste with municipal solid waste is no longerconsidered an appropriate management practice. Cur-rently all but a few hazardous wastes are able to be pre-treated to render them non-hazardous with respect todisposal in well-sited and well-designed municipalsolid waste landfills.

It is recognised that the municipal solid waste streamcontains a small proportion of hazardous waste fromhouseholds and small commercial premises that stand-ard waste screening procedures will not exclude fromlandfills.

Waste acceptance criteria should comprise prescribedlists that set out those wastes that are not acceptable andleachability criteria for wastes, which may includetreated hazardous waste, that may be accepted.

Prohibited Wastes

Prohibited wastes are those, which due to their inher-ent characteristics, can impact on the safe operation ofa landfill and pose a threat to people and the environ-ment. A detailed list of characteristics of wastes thatshould be prohibited from municipal solid wastelandfills, and types of waste that may exhibit thesecharacteristics, is contained in Appendix 4 (Section A).

Some prohibited wastes may be acceptable in landfillsthat have engineered retention and high standardleachate collection and treatment systems, followingtreatment to remove their hazardous characteristic(s).

Acceptable Wastes

A detailed list of characteristics and types of wastes,which may be acceptable in a municipal solid wastelandfill following treatment to render them non-haz-ardous with respect to landfill disposal, and types ofwaste that may exhibit these characteristics, is con-tained in Appendix 4 (Section B).

Waste acceptance criteria for these wastes shouldensure that:

• landfill leachate does not differ from that whichwould be expected from non-hazardous municipalsolid waste; and

• there is no threat to groundwater and/or surfacewater receptors from wastes deposited in the landfill.

In the absence of any national requirements for landfill

waste acceptance criteria, the following approach isrecommended for well-sited landfills, which providean equivalent level of environmental protection asthose using designs recommended in Section 4.7.

Use of the USEPA Toxicity Characteristic LeachingProcedure (TCLP) and maximum leachability limitsusing the following are recommended in setting wasteacceptance criteria:

• USEPA TCLP criteria, detailed in Appendix 5; and

• NSWEPA leachability criteria for “Solid WasteLandfills”, detailed in Appendix 6.

The NSWEPA waste acceptance criteria for “SolidWaste Landfills” also include total concentration lim-its to be used together with leachability limits, inaccordance with the NSWEPA assessment procedures.

The use of the above as acceptance criteria provides areasonable assurance that wastes accepted at an appro-priately sited and designed landfill will not result inadverse effects on the surrounding environment.

For contaminants where appropriate TCLP limits donot already exist, it is recommended that TCLP limitsbe set by a site-specific risk analysis based on thecontaminant’s characteristics and flowpaths togroundwater and surface water receptors, or settinglimits at the “lesser of” following;

• NZS 9201 Model Trade Waste Bylaw limits;

• 100 times the New Zealand drinking water stand-ard;

• 1000 times the guidelines for protection of aquaticspecies.

Landfills that do not have demonstrated retention andleachate collection systems, or where groundwater orsurface water is already contaminated, should usemore stringent acceptance criteria.

Notification of CustomersThe next step in controlling the entry of wastes intolandfills is to notify potential customers, landfill opera-tors and regulators of the waste acceptance policy forthe various sites. Specific policies and procedures fornotification of customers are discussed below.

Waste Disposal Application

Commercial and industrial landfill users should com-plete a formal application to deposit waste prior tobecoming a user of a site, or in the case of regulardeliveries, before there is a change to the nature orvolume of the waste being disposed of at a site. The


application should identify the nature and volume ofthe waste to be disposed of at a site, and any additionalrelevant information. The applicant should be requiredto agree not to dispose of waste of a different nature ormarkedly different volume except with the prior con-sent of the landfill owner/operator and to attest to theveracity of the information contained within the appli-cation.

The disclosure of the nature of the waste will allow theowner/operator to evaluate the waste in a careful man-ner, requiring the generator to perform whatever testsare needed to characterise the waste. The disclosurealso provides the basis for a record of the nature andvolume of the waste disposed of to the landfill. (If anational manifest system for the storage, use and dis-posal of hazardous substances were to be implemented,the final copy of the manifest would form part of thedisposal records of the site.)

Assessment of Application

The landfill owner/operator should evaluate the com-pleted application against the specific requirements ofthe WAC. Wastes that meet the criteria could beadmitted and disposed in the landfill. If additionaltests to better characterise the waste are required, thegenerator should arrange for these tests to be per-formed.

Those wastes that do not meet the requirements may beable to be treated in such a way that they meet thecriteria before being accepted at the landfill. Somewastes may not be able to be accepted regardless oftreatment. Failing successful treatment, alternative dis-posal facilities will need to be identified and used. Insome cases involving complex waste issues, assess-ment of the application by a regulatory authority maybe necessary.

Acceptance Agreement

Acceptance of a satisfactorily completed waste dis-posal application provides the basis of a waste accept-ance agreement. The agreement should also containdetails of sanctions available to the landfill operatorshould the applicant breach the terms of the agreementto accept waste. It should also set out the rights of thelandfill operator to inspect, challenge, sample, test and,if necessary, reject any waste brought by the applicantto the site for disposal.

Notification of Alternatives

If the application for disposal of waste cannot beaccepted, then the operator of the landfill should berequired to advise the applicant of any known facilitiesthat are able to accept the waste for storage or disposal.

Alternatively, the landfill owner/operator should referthe waste generator or transporter to the regional coun-cil or other entity for further information on suitabledisposal facilities.

A similar procedure should be followed if waste was tobe turned away from the landfill following inspectionand an identified breach of the acceptance agreement.In that case, the landfill owner/operator should alsoadvise the regulatory authority that the particular wastehad been illegally presented for disposal and rejected.

Site ProceduresThe final step in controlling the entry of waste intolandfills is to implement policies and procedures todetect and deter illegal disposal of these wastes. Spe-cific procedures that should be implemented are de-scribed below.

Random Load Inspections

The landfill owner/operator should implement a pro-gramme that involves performing random inspectionsof incoming waste. This should involve detailed screen-ing of loads to confirm the nature of the waste. Themethodology should allow for selecting loads on arandom basis, and the frequency of inspections shouldbe based on the type and quantity of wastes receivedand the findings from previous inspections.

Random inspection of one load in every 50 commercialand industrial loads is suggested as an initial guide.However, if these inspections or other findings indi-cate that inappropriate waste is being received at a site,then the random programme should be modified toincrease the frequency of inspections.

Notification of Authorities

The landfill owner/operator should notify appropriateauthorities if hazardous waste is presented at the landfillfor disposal without prior approval and appropriatedocumentation. These authorities may include the re-gional council or unitary authority, or other appropri-ate organisation.

If the landfill owner/operator identifies the hazardouswaste while it is in the possession of the transporter, theload should be rejected and will remain the responsibil-ity of the transporter.

If the hazardous waste is identified after deposition atthe tipping face, then immediate steps must be taken tosecure the waste. Contingency plans for identificationof the waste must be urgently implemented. If thewaste is identified as unacceptable then a plan forremoval or neutralisation of the waste must be actionedas quickly as practicable. Landfill users and staff must


be protected from any health and safety hazards thatmight be caused by the hazardous waste.

Record Keeping

Landfill owners/operators should maintain an operat-ing record that includes information on waste accept-ance, on-site recycling, load inspections, and opera-tional activities. Information on waste acceptance andon-site recycling should include the quantity and, wherepossible, classification of wastes according to the Min-istry for the Environment’s Waste Analysis Protocol.

Information on load inspections should include:

• date and time wastes were received for inspection;

• sources of the wastes;

• vehicle and driver identification;

• observations made by the inspector;

• notification of violations; and

• notification of authorities.

Information on operational activities should includerecording of disposal locations and training.

Supervision of the Tipping Face

Supervision of the disposal activity at the working faceshould be maintained when wastes are received at thelandfill to ensure the accountability of those depositingunacceptable wastes at the site. Where a facility re-ceives in excess of 500 tonnes per week (25,000 tonnesper annum), this supervision should be undertaken bysomeone other than the compactor driver.

Recording of Disposal Location

A landfill owner/operator at a site receiving wastes thatrequire special handling procedures (for example,treated hazardous waste) should record the location ofthose wastes when placed into the landfill, including:

• type of waste;

• quantity of waste; and

• location of waste (surveyed or identified on a siteplan).

5.7 RoadingRoads at landfill sites provide access to the site gener-ally, the working face, special facilities (such as leachatecontrol systems, stormwater control systems, andlandfill gas control equipment), and for construction

traffic. Permanent access roads between the site bound-ary and entrance facilities, including reception areas,weighbridge and wash-down facility, should, ideally,be sealed to a good standard.

Internal access roads beyond the entrance facilitiesshould be aligned with easy gradients and should,wherever practicable, follow perimeter routes on goodfounding to minimise reconstruction and relocation asfilling progresses. Any access road that will be inservice for six months or longer should ideally besealed. Access across the refuse should be constructedfrom a layer of heavy road metal.

5.8 Visual ImpactsVisual impacts associated with the operation of landfillscan be minimised by following the recommendedoperating practices and conducting waste disposalactivities behind purpose-built earth screening bunds.Landfills can also be screened by means of vegetationand/or placing shade-cloth screening at specific loca-tions around the property. The benefit of these meas-ures is to reduce visual impacts associated with landfilloperations.

Planting around the perimeter of the site should becommenced at the earliest opportunity, utilising fast-growing varieties of vegetation in order to establishboth a visual barrier and some degree of wind protec-tion to site operations.

5.9 Waste Compaction

Equipment SelectionA landfill should utilise appropriate equipment forenvironmentally responsible and safe operation of thesite. A number of factors should be taken into accountwhen selecting equipment to be used on-site, includ-ing:

• site characteristics;

• site preparation requirements;

• daily waste input quantity;

• type of waste;

• density of waste;

• cover requirements including the type of cover; and

• operator comfort and safety.

Backup equipment should be available for use in the


event of mechanical breakdown and also to cover fornormal maintenance downtime.

Waste PlacementThe width of the working face should be kept as narrowas possible in order to minimise the area of exposedrefuse. There must, however, be sufficient room topermit vehicles to manoeuvre and unload quickly andsafely. A balance must be achieved between the numberof incoming vehicles and the need to minimisestormwater infiltration, cover requirements and odourand litter nuisances.

Waste CompactionThe amount of landfill space and land used to disposeof waste can be minimised by proper compaction.Compaction also improves the stability of landfills,and minimises the voids that would encourage vermin,fires or excess generation of leachate.

Refuse should be placed against a clay starter embank-ment or the previous day’s refuse. As soon as it isunloaded, the refuse should be spread out in thin layersto form individual lifts. Pushing waste over a verticalface is not considered to be acceptable. The layersshould be sloped away from the sides and final surfacesof the landfill, so as to minimise the chance of leachatetracking to the edge of the fill and breaking out on thesurface.

Each progressive layer should be 300 mm to 600 mmthick. The number of passes by a machine over thewaste to achieve optimum compaction will depend ona number of factors, including the type of machine, itsground pressure, the type of waste and the slope.Obviously, the more passes made over the waste, thebetter its compaction, but operational considerationsgenerally limit the number to between three and fivepasses.

Typically, lifts are between two and four metres thick,depending on the daily volume of refuse deposited atthe site, however, heights of up to ten metres can becommon in large operations.

Landfill operators are expected to ensure that maxi-mum compaction is achieved for the capacity of themachines used. For landfills receiving over 50,000tonnes of waste per annum, the waste compaction goalshould be at least 800 kg/m3, excluding cover material,as measured by a compaction test. For landfills receiv-ing less than 50,000 tonnes of waste per annum, thewaste compaction goal should be at least 600 kg/m3,excluding cover material.

Bulky refuse items require special measures in their

placement. Such items should be crushed by somemechanical means to reduce void space prior to place-ment at the base of the working face. These itemsshould not be placed in the first lift of refuse, due to therisk of liner damage. Similarly, bulky items should notbe placed in the final lift since settlement of the refusemay result in such items piercing the cap.

5.10 CoverUse of soil cover material helps to provide the fullrange of environmental management objectives bylimiting run-on and infiltration of water, controllingand minimising risk of fire, minimising emissions oflandfill gas, suppressing site odour, reducing fly propa-gation and rodent attraction, and decreasing litter gen-eration. Similarly, scavenging is reduced by removingthe waste from view.

Daily CoverDaily soil cover should be provided at all landfills,except where it can be shown that no significantadverse impact would occur without cover. Daily covermay be of any soil type and should only be applied afterthe refuse has been placed, compacted, and trimmed tothe proper grade. A minimum of 150 mm of covermaterial should be placed over exposed refuse at theend of each operating day.

If low permeability soils are used it may be necessaryto penetrate daily cover prior to refuse placement toavoid problems associated with perched water tables.

To ensure that there will always be sufficient covermaterial available to meet performance requirements,operators should maintain a stockpile or an area wherecover can be won on-site in all weather conditions,which will be adequate to meet cover requirements ofthe landfill for two weeks.

Alternative Daily CoverIn order to maximise the available landfill capacity andavoid excessive stratification of the refuse, considera-tion should be given to the use of alternative daily covermaterials. Alternative daily cover is typically placedon the active face in lieu of soil. Types of alternativedaily cover include:

• geosynthetic blankets;

• shredded green waste;

• sawdust;

• spray on foam;


• contaminated soil (that complies with waste ac-ceptance criteria);

• ash (that complies with waste acceptance criteria);

• stabilised sludge;

• paper pulp;

• composted material;

• small weave netting; and

• heavy-duty reusable plastic sheets or tarpaulins.

The selection and use of appropriate alternative covermaterials requires consideration of a number of fac-tors, including:

• availability of material;

• ease of material handling;

• climatic conditions;

• additional nuisance potential;

• potential contaminants within the material; and

• potential effect on site stability.

Landfill operators can specify alternative cover mate-rials provided they can demonstrate compliance withperformance requirements.

Intermediate CoverIntermediate cover is used to close off a cell that willnot receive additional lifts of refuse or final cover forsome time. A minimum thickness of 300 mm of soilshould be placed as soon as the refuse achieves therequired cell profile. Intermediate cover surfaces thatwill remain exposed for a period exceeding threemonths should be temporarily grassed using conven-tional methods or by hyroseeding.

When refuse is placed over an area where an interme-diate cover has been applied, it is important to ensurethat the cover is adequately penetrated or removed torender the surface permeable to gas and leachate. Ifthis is not done, the landfill may become stratified withimpermeable layers, and perched leachate lenses coulddevelop, with the possibility of surface breakouts. Gascould be horizontally dispersed with a tendency forlateral migration.

Final CoverSite capping and revegetation should ensure that thefinal surface provides an appropriate barrier to waterinfiltration in accordance with design philosophy, con-trols emissions to water and the air, promotes sound

land management and conservation, prevents hazardsand protects amenity. A final cover system generallyincludes (from bottom to top):

• intermediate soil cover;

• low permeability layer; and

• topsoil layer.

In addition, a final cover system can also include agranular gas drainage blanket, or a geosynthetic mem-brane below a subsoil drainage layer. Final covermaterial should be placed as soon as practicable overfinished areas of the landfill above the previouslyplaced intermediate cover, when weather conditionsare suitable.

Details of final cover design are discussed in Section4.12.

Vegetation on the final cover should be establishedimmediately following completion of the cover.

The achievement of design objectives for the sitedepends on final cover being installed diligently inaccordance with design requirements. Ongoing moni-toring and maintenance of final cover following place-ment is also necessary to remedy the effects of settle-ment, cracking or vegetation die-off.

5.11 Nuisance Control

LitterUncontrolled litter can contribute significantly to theloss of amenity experienced at a landfill site. As a basicrule, all litter outside the tipping area should be re-trieved on a daily basis.

Litter control nets and fences should be erected aroundthe perimeter of the area being filled. Relocatablebarrier-type fences can also be placed immediatelyadjacent to the active working face as required. Netsand fences should be inspected and cleared regularlyon a daily basis, or more often if needed.

DustThe main activities responsible for dust generation onsite are:

• disturbance of dried soils on access roads as a resultof wind or traffic movements;

• earthworks, such as the placing of cover materialduring dry periods; and

• filling and compaction of dust-type refuse.


In order to minimise dust emissions, permanent accessroads between the site boundary and entrance facili-ties, including reception areas, weighbridge and wash-down facility, should be sealed to a good standard.Unsealed roads should also be sprayed by water cartand sealed roads cleaned by mechanical road sweepersas required, especially during dry periods. If roadshave speed humps and are properly maintained, dustproblems will be kept to a minimum.

Modern landfill design and operation is based oncareful control of liquids which may enter the landfill.Water, as a dust control measure, must be used verycarefully. Water can enter the landfill and contribute tothe formation of leachate. Indiscriminately appliedwater can also enter the groundwater and impact thegroundwater monitoring wells.

In addition, dust-type waste should be considered a“special” or difficult disposal waste. The waste gen-erator or transporter should be required to dampendown the load before delivery to the site.

Dust controls should minimise pollutants leaving thesite as airborne dust, reduce stormwater sediment load,and protect local amenity. The generally expectedmaximum level for dust deposition is 4 gm/m2 permonth as an annual mean for total solids, but the limitcould be lower for landfills adjacent to sensitive areas.The deposition rate from the landfill should not beexceeded outside the site boundary.

OdourThe main sources of odour on a landfill site are:

• inadequately covered waste at the working face;

• highly putrescible loads of refuse;

• excavations into old refuse;

• leachate; and

• landfill gas.

The landfill operator needs to take appropriate goodhousekeeping steps to prevent the production of odours.The size of the working face should be kept to aminimum and the use of daily cover and immediateattention to odorous waste loads will minimise thetransmission of odours off-site.

Odour from incoming waste loads should also beminimised by requiring the generators of odorouswaste to deliver the waste prior to putrefaction or, ifappropriate, treat it to combat odours before delivery.Loads not complying with these requirements shouldbe refused entry and returned for treatment. Odoursoriginating from the generation of landfill gas can be

controlled by the implementation of landfill gas con-trol systems.

Application of deodorant chemicals by spray near theworking face, or in areas of excavation in old refuse canbe used to control odours. Excavations in old refuseshould be kept to a minimum.

Odours can also be caused by emission of landfill gasand release of volatile organic compounds fromleachate. Odours from landfill gas will be minimisedby timely cover system construction and maintenance,and implementation of landfill gas controls. Leachateodours can be controlled by using pipes and coveredstorage facilities to limit escape of volatile organiccompounds.

A landfill that is identified as having a potential odourimpact should install and operate an on-site meteoro-logical station which monitors wind speed, wind direc-tion, fluctuations in wind direction, and temperature.The landfill operator should maintain a record ofcomplaints regarding odours. This should be corre-lated with weather conditions and deliveries of particu-lar wastes.

BirdsBirds, particularly gulls, can be attracted to landfillsites in large numbers for water, food, nesting orroosting. The birds may transfer pathogens to drinkingwater collection or storage areas and crops, as well asdepositing excreta and food scraps. Birds can alsopresent a hazard if the landfill is located near anairfield.

Birds should be discouraged from the landfill site fromits establishment so behavioural problems do not be-come established. In addition, sudden imposed controlon access by birds to landfilled refuse can lead to birdsseeking alternative food sources. This can impact onother bird species, including endangered native spe-cies, whose eggs can become a food source for thelandfill birds.

Landfills that do not operate continuously often pro-vide a unique roosting habitat due to elevated groundtemperatures and freedom from disturbance. Nestingcan be minimised by examining the nesting patternsand requirements of undesirable birds and designingcontrols accordingly. For example, nesting can becontrolled for certain species by mowing and mainte-nance schedules.

Measures can be adopted to minimise the attraction ofbirds to the landfill. These include:

• good litter control;


• minimising the uncovered working face;

• prompt and thorough compaction of refuse;

• covering refuse at the end of each day;

• special handling of highly organic waste; and

• minimising exposed earthworks and shallow poolsand puddles of water.

If birds start to develop a pattern of attraction to the sitethere are additional control measures that can be imple-mented, including:

• increasing cover thickness;

• changing cover type, density or frequency of appli-cation;

• use of mobile high wires;

• special kites, including realistic models of the bird’snatural predators;

• bird scare audio recordings;

• shooting of species not protected by law;

• composting or processing of organic wastes beforedisposal; and

• shredding, milling or baling of waste containingfood sources.

Varying bird control techniques may prevent birdsfrom adjusting to a single method.

FliesFlies may become a problem during the summer months,particularly when there are delays between collectionand deposition of waste. Eggs laid in putrescible refusemay hatch over this period. Flies are capable oftransmitting salmonella and other food-borne diseasesthrough mechanical transmission.

Prompt, good compaction and application of cover areessential to the control of flies. This eliminates food,shelter and breeding areas. In bad cases of fly infesta-tion the application of insecticides may be necessary.

VerminRats can spread disease, cause property destructionand contaminate food. They are difficult to eliminateonce a colony is established. Rat populations occurbecause they are brought to the site in loads or migrateto the site. Appliance storage areas, voids in bulky ordemolition wastes, or poorly compacted cover soilscan create shelter.

The most satisfactory way to counter rat infestation is

by effective site management. Prompt, good compactionand application of cover are essential to the control ofrats. It is also desirable to arrange a system of regularvisits and precautionary action by a pest control con-tractor.

Measures that can be adopted to minimise the attrac-tion of vermin to the landfill include:

• increasing cover thickness;

• changing cover type, density or frequency of appli-cation;

• composting or processing of organic wastes beforedisposal;

• shredding, milling or baling of waste containingfood sources; and

• use of poison bait.

If alternative cover materials or systems are used, thelandfill operator should identify the method by whichit can quantitatively monitor changes in vermin popu-lation as a result of the new cover. A plan to managevermin should be developed.

NoiseExcessive noise can also contribute significantly to theloss of amenity experienced at a landfill site. The noisegenerated during the operation of a landfill should bemanaged so that the following objectives can be met:

• noise from any single source does not intrudegenerally above the prevailing background noiselevel; and

• the background noise level does not exceed thelevel appropriate for the particular locality andland-use.

The determination of an appropriate noise limit for asite will therefore depend on the adjacent land use, theexisting background noise and the nature of the noisesource.

Acceptable noise attenuation measures could includebuffer zones, acoustical barriers, and acoustical treat-ment of equipment. Good bunding design will ensurelimitation of noise from the site. All on-site mechani-cal plant and equipment should be maintained in a goodstate of repair and be fitted with appropriate silencersor mufflers to minimise noise. Particular attentionshould also be paid to the design of items such as speedhumps and vibration grids to prevent noise generation.Effective noise control can also be accomplished byrestricting hours of operation to coincide with adjacentland uses.


5.12 Fire PreventionLandfill fires can cause health effects to people ex-posed to the emission of pollutants from burning refusesmoke. This is due to the low burning temperature andincomplete oxidation of the burning refuse. In addi-tion, landfill fires can create physical hazards forlandfill personnel and users, such as burns, explosions,subsidence, and exposure to hazardous materials.

Landfill fires can generally be attributed to one of thefollowing factors:

• delivery of undetected burning material;

• delivery of highly flammable materials;

• combination of reactive materials within the fill;

• spontaneous combustion through aerobic decom-position;

• malicious intent by site trespassers;

• cigarette smoking; and/or

• flammable debris on hot parts of equipment.

The adoption of good site management practices shouldminimise the risk of fire from any of these factors.Landfill fires can generally be classified either assurface fires or deep-seated fires. Surface fires are firesin recently deposited refuse in the landfill workingface. Deep-seated fires are found at depth in materialdeposited months or years previously.

Surface FiresSurface fires can be started by any of the causes listedabove.The best way to control and extinguish a surfacefire is to smother it with large volumes of wet or dampsoil. To accomplish this fire fighters may have to wetthe fire to extinguish any flames and cool the area. Thefire should then be covered as rapidly as possible.

Deep-seated FiresDeep-seated fires are started by spontaneous combus-tion through aerobic decomposition. Ensuring thatrefuse is placed in a well-compacted state shouldprevent the occurrence of deep-seated internal fires.However, care should also be taken to ensure that theinterior of the fill is maintained in an oxygen depletedstate. In particular, an active landfill gas extractionsystem in the vicinity of the working face, or areas withonly intermediate cover, can result in high oxygenlevels in the refuse and the establishment of aerobicconditions. The resulting temperature rise can lead tocombustion within the fill. Increased temperatures atgas extraction points may indicate that aerobic condi-tions are developing.

The area of the deep-seated fire should be identifiedand surcharged with large volumes of clay or similarmaterial. This minimises the number of outlets forgases to escape and reduce the entry of air to the fire.The area should be checked daily for heat, smoke,cracking and subsidence. Landfill gas extraction shouldbe stopped in the vicinity of the fire, but wells shouldbe checked for temperature and carbon monoxide.Landfill gas vents and extraction wells should besealed to prevent escape of combustion gases and entryof oxygen. If practical, the area of the fire can beisolated by deep trenches backfilled with clay.

Management ProvisionsGood landfill management practices should minimisethe potential for fires. These practices should include:

• fire breaks constructed around landfill cells;

• prohibition on all forms of deliberate burning;

• no smoking on site;

• screening of wastes;

• close control of waste deposition; and

• good compaction and cover.

Fire-fighting equipment should be maintained on-siteand operations staff should be trained in the use of suchequipment and techniques for dealing with surfacefires and deep-seated fires. The Fire Service should beconsulted regarding training and establishment of fire-fighting procedures.

Equipment available on site should include:

• an adequate permanent water supply;

• fire extinguishers; and

• protective clothing and breathing gear.

In addition, at larger landfills equipment should in-clude:

• a water cart fitted with a high-pressure hose system;and

• specialist chemical spill agents and foams.

Further information on landfill fires is contained in thedocument Hazards of Burning at Landfills (MfE, 1997).

5.13 Water Control

Leachate

Leachate Generation

The control of leachate is fundamental to the protection


of water quality. Surface water should be controlled toprevent water ingress into the landfill and consequentformation of leachate. Groundwater entry is anotherpotential contributory source to the formation ofleachate. Control of groundwater entry is primarilydependent on the design and construction of the landfillliner system.

Prohibition of the disposal of bulk liquid wastes shouldalso be implemented to control waste that may alsobecome a source of leachate. Liquid waste refers to anywaste material that is determined to contain free liq-uids. This is usually defined by SW-846 (USEPA,1987) “Method 9095 – Paint Filter Liquids Test”. Onecommon waste stream that may contain a significantquantity of liquid is sludge.

Leachate Control

Leachate collection, removal and disposal systemsshould be fully operable prior to the disposal of refusein a particular area. A regular programme of preventa-tive maintenance for leachate control systems shouldbe required. Typical items that should be addressedinclude:

• regular inspection of leachate drainage and treat-ment systems;

• flushing of leachate systems; and

• servicing of pumps.

To improve the flow of leachate and prevent perchedleachate lenses, the operator should break up or removepreviously applied daily or intermediate cover prior tofurther filling.

Leachate should generally be disposed by one of thefollowing methods:

• discharge to community sewerage system, with orwithout pre-treatment;

• discharge to land by spray or subsurface irrigation,with or without pre-treatment;

• discharge to natural water after treatment;

• injection/recirculation into the landfill; and

• evaporation using heat generated from the combus-tion of landfill gas.

Leachate Monitoring

Because of the complex processes operating within thelandfill, and their potential environmental effects, moni-toring is required to confirm that the landfill is behav-ing as predicted and to provide management informa-

tion. It can indicate the effectiveness of attenuationprocesses or any treatment processes (such asrecirculation) used. Changes in composition can act asa warning and assist in identifying problems such asoverloading with a particular waste. Environmentalmonitoring will generally also be necessary to confirmthat effluent quality is within the discharge consentconditions.

The monitoring programme will be site-specific, butambient measurements should be obtained prior tocommencement of operations to determine the envi-ronmental effect that can be directly attributed tolandfilling operations.

Stormwater

Stormwater Control

Stormwater should be controlled to prevent wateringress into the landfill and consequent formation ofleachate. In addition, stormwater should be controlledto prevent erosion and excessive sediment discharge towaterways.

Surface water from outside the area of exposedearthworks should be diverted around the perimeter ofthe works. Surface water from within the area ofexposed landfill earthworks should be treated in siltretention systems prior to discharge in accordance withresource consent requirements. The access road to theworking face should be aligned to prevent it fromchannelling surface water to the face. Side channels onaccess roads should be intercepted short of the face anddiverted away from the filling area. Surface water thatcomes into contact with waste should be treated asleachate.

A regular programme of preventative maintenance forstormwater control systems should be undertaken.Typical items that should be addressed include:

• regular inspection of stormwater drainage and treat-ment systems;

• cleaning sumps;

• dredging silt ponds;

• clearing culverts;

• servicing pumps; and

• reinstatement of eroded areas.

The exposed or cleared areas of the landfill should beminimised at all times, and topsoil set aside forrevegetation purposes. All completed areas of thelandfill should be progressively revegetated, and any


areas exposed for greater that a month should bestabilised to minimise soil erosion.

Landfill washouts can occur during periods of highintensity rainfall. Remedial work must be undertakenas soon as practicable to minimise any adverse envi-ronmental effect. If not repaired, relatively minorwashouts can result in a release of refuse, leachate andgas, and promote landfill instability. Depending on theseverity of the washout, proper repair and reinstate-ment may involve substantial effort.

Stormwater Monitoring

Because of potential environmental effects, monitor-ing is essential to confirm that the stormwater controlsystem is behaving in the ways predicted when the sitewas designed and permitted, and to provide manage-ment information. Environmental monitoring will alsobe necessary to confirm that water quality is within thedischarge consent conditions. The monitoring pro-gramme will be site-specific, but ambient measure-ments should be obtained prior to commencement ofoperations to determine the environmental effect thatcan be directly attributed to landfilling operations.

5.14 Landfill Gas Management

Landfill Gas GenerationLandfill gas is produced when solid wastes decom-pose. The quantity and the composition of gas dependon the types of solid waste that are decomposing.Methane (CH4) and carbon dioxide (C02) are the majorconstituents of landfill gas. Other gases are alsopresent and some may impart odour. Hydrogen sul-phide may be generated at a landfill if it contains a largeamount of sulphate such as gypsum board. Non-methane organic compounds (NMOCs) are also presentand may impact on air quality when emitted throughthe cover or vent systems.

Landfill Gas ControlA landfill gas control system can have a number ofobjectives, including:

• sub-surface migration control, to reduce or elimi-nate the risk of explosion on or off the site;

• odour control, to eliminate odour nuisance that canaffect neighbours and site personnel;

• landfill gas to energy by electricity generation ordirect gas use; and

• greenhouse gas emission control, to reduce themethane discharge to the atmosphere.

Landfill operations should encourage gas movementsthat are consistent with the collection system provided.The landfill will generally be stratified in a way thatresults in horizontal gas flow within the layers. Thesepathways should be intercepted by elements of the gascollection system. These will include horizontal col-lectors, vertical extraction wells, or cut-off trenches ifmigration is severe. Care should be taken to ensure thatno unintentional gas routes (for example servicetrenches) result in uncontrolled gas migration.

Gas will build up under the finished landfill final coversystem. Gas migration or emission is likely if measuresare not taken to prevent pressure build up and maintainthe integrity of the cover system. This can be particu-larly important in times of very dry weather if the finalcover system is susceptible to cracking. Other factorsto be taken into account from an operational perspec-tive include the effect of a change in atmosphericpressure on gas migration patterns.

Any landfill gas condensate collected should be han-dled in the same manner as leachate, with the exceptionthat it should not be spray irrigated because of low pHand potential odour.

A regular programme of preventative maintenance forall gas control systems should be undertaken. A large,complex landfill gas control system may require dedi-cated technical staff to be established on-site. Simplesystems may only require routine inspection. Servicepersonnel should normally be available on an on-callbasis in the event of a system malfunction.

Landfill Gas MonitoringLandfill gas monitoring should be undertaken at alllandfill sites, primarily to determine whether gas pro-duction is giving rise to a hazard or nuisance. Monitor-ing should commence approximately six months afterestablishment of the landfill and continue until landfillgas production has fallen below the level where itconstitutes a risk. For most sites this will be in excessof 30 years after closure.

Control system monitoring should include the quan-tity, temperature (in the landfill), pressure and primarycomposition of gas extracted from the landfill. Minorconstituents (hydrogen sulphide, non-methane organiccompounds) should be monitored depending on thetreatment (if any) of the landfill gas.

Migration monitoring should be concentrated at loca-tions considered to be most at risk and should providea clear indication of the changes in gas quantity,composition and movement with respect to time. Pres-sure and temperature can also be relevant.

Surface emission monitoring should demonstrate that


the cover material and extraction system is controllingthe emission of landfill gas. The landfill operatorshould arrange testing of the atmosphere with appro-priate equipment a short distance above the groundsurface in areas of intermediate or final cover wherewastes have been placed.

The safety of personnel involved in monitoring mustbe carefully considered. Written safe working proce-dures should be adopted and practised prior to under-taking gas monitoring.

5.15 Closure and After-care

ClosureUpon completion of waste disposal operations in partof a landfill, closure works should be undertaken assoon as practical. The closure works will include:

• construction of the final cover system, includingfinal stormwater and erosion control structures;

• revegetation of the landfill cap; and

• construction of the final landfill gas and leachatecontrol structures.

Construction of ground water control systems may alsobe necessary for old landfills that are subject togroundwater ingress.

The aim of these works is to provide for the continueddecomposition of the disposed wastes in a safe andenvironmentally-sound landfill structure. Site cappingand revegetation should ensure that the final surfaceprovides a barrier to migration of water into the wasteand controls discharges of landfill gas and leachate. Itshould also promote sound land management andconservation, prevent hazards and protect amenity.

During the closure process operations personnel willbe required to maintain leachate, stormwater and landfillgas control systems while the final cover system isunder construction. Additional care will be required tomaintain surface water standards during the earthworks

associated with final cover construction. Monitoringshould continue during the closure works.

After-careThe natural processes within landfills continue to pro-duce leachate and gas that require environmental man-agement for many years after landfilling. Operationsto support environmental management should be un-dertaken in the post-closure period. Post-closure op-erations should follow the direction of a closure planprepared to reassess the provisions made during thedevelopment of the landfill. The plan should take intoaccount the status of the landfill and the degree ofcontrol over the release or migration of contaminantsfrom the landfill. The plan should specify:

• the steps to be taken in stabilising the site and thetime frame required;

• the requirements for all leachate, landfill gas, andstormwater control systems, and monitoring andreporting practises to be maintained during theafter-care period; and

• contact arrangements for adjacent property ownersto maintain communications with operations per-sonnel.

These operations would typically include:

• leachate collection and disposal;

• landfill gas control;

• monitoring of site integrity;

• repairs to the final cover system;

• maintenance and control of vegetation;

• stormwater and sediment control; and

• monitoring of groundwater, surface water andlandfill gas.

Monitoring for environmental effects and site integrityshould be continued until the landfill no longer has thepotential for adverse environmental effects. Remedialactions should be completed as required.

Landfill Monitoring • 65

Chapter 6Landfill Monitoring

6.1 IntroductionMonitoring of landfills is necessary to confirm thatthey are performing as expected, in accordance withdesign, operational practices and regulatory require-ments, and that discharges are not resulting, or likely toresult, in adverse effects on the environment.

Monitoring requirements need to be developed on asite-specific basis, taking into account:

• landfill size;

• geological and hydrogeological characteristics ofthe site; and

• proximity to, and sensitivity of, surrounding envi-ronments.

This section addresses:

• objectives of monitoring;

• leachate monitoring;

• groundwater monitoring;

• surface water monitoring;

• analysis and review of monitoring data; and

• landfill gas monitoring.

6.2 Objectives of MonitoringThe physical, chemical and biological breakdown ofrefuse within a landfill produces leachate and landfillgas.

Leachate discharging through the base of a landfill cancontaminate groundwater, leading to contamination ofsurface water. Leachate can also contaminate surfacewater via discharges from the landfill surface andstormwater management systems.

Landfill gas can give rise to asphyxiation and explo-sion hazards, and odour nuisance.

The objectives of monitoring at and around landfillsites are to:

• determine baseline environmental conditions atand around the landfill site;

• determine processes occurring within landfillsthrough monitoring of leachate production, leachatecomposition and landfill gas composition;

• determine effects on the environment due to thelandfill through monitoring of groundwater, sur-face water and landfill gas;

• check compliance with resource consent(s) andother regulatory requirements; and

• identify the need for, and the extent of, remedial/mitigation measures to reduce effects on the envi-ronment.

Monitoring of groundwater, surface water and landfillgas needs to be continued during the aftercare period ofthe landfill, until the strength of any discharges hasreduced to a level at which they are unlikely to have anyadverse effects on the environment. This aftercareperiod is likely to be at least 30 to 50 years.

6.3 Leachate Monitoring

Purpose of Leachate MonitoringThe quantity, composition and strength of leachateproduced from a landfill depends on the compositionof the landfilled waste and the rate of infiltration ofrainwater and, possibly, groundwater.

Leachate monitoring should be undertaken at anylandfill where it is collected in order to:

• monitor the degradation processes taking placewithin the landfill;

• manage and protect leachate treatment and dis-posal systems;

• monitor compliance with trade waste dischargelimits (where applicable); and

• refine groundwater and surface water monitoringprogrammes.

Monitoring should include:

• regular measurement of the quantity of leachateproduced;

• determination of leachate strength and composi-tion; and


• monitoring changes in leachate strength and com-position over time.

Monitoring LocationsIn order to monitor landfill processes in different partsof the site and over time, it is preferable to monitorleachate quantity and composition from each discretecell, or each leachate abstraction location.

Monitoring Parameters and FrequencyIn general, leachate should be monitored regularly fora full range of parameters appropriate to the types ofrefuse accepted at the site.

Analysis of the leachate chemistry can be used tomodify the parameters to be monitored in groundwaterand surface water, in cases where monitoring uses asmall number of leachate indicator parameters.

If the concentration of a parameter increases by asignificant amount in leachate it should be added togroundwater and surface water monitoring pro-grammes, particularly if leachate contamination isalready evident.

Leachate monitoring should, ideally, be undertaken onat least an annual basis, and more frequently dependingon:

• requirements for the management of leachate treat-ment/disposal systems;

• groundwater level fluctuations; and

• rate of leachate migration or groundwater flow.

Table 6.1 gives is a list of chemical parameters thatwould typically be included in a leachate monitoringprogramme for a regional landfill.

Detection LimitsA detection limit relates to the lowest level that aparticular analysis method can detect a parameter 99%of the time. Detection limits should be set within asampling plan and be based on the likely concentrationrange of the parameter in leachate. Because of theconcentrated nature of leachate, use of detection limitssignificantly higher than those required for groundwaterand surface water monitoring may be possible for someparameters.

6.4 Groundwater Monitoring

Purpose of Groundwater MonitoringAs prime receptors of wastes located within natural

settings, landfills inherently pose issues for retentionof contaminants. Groundwater can be at risk fromescape of leachates through the base of the fill mate-rials and/or from ancillary activities such ascomposting. In some situations, groundwater can bedirectly disturbed by site construction activities.Groundwater monitoring seeks to identify actual orpotential effects on the resource as part of the overallenvironmental management of the site. In particular,groundwater monitoring seeks to achieve the follow-ing purposes:

• provide data for engineering design and obtainingregulatory consent for a landfill;

• provide pre- and post- construction baseline waterquality data;

• check compliance with landfill operating and regu-latory standards; and

• identify any need for mitigation and/or remediation.

Objectives of Groundwater MonitoringMonitoring objectives usually seek to achieve reliable,long-term information about the behaviour ofgroundwater at a site and the effects from the landfill.However, obtaining reliable and pertinent informationon groundwater behaviour and characteristics requiresa sufficient understanding of hydrogeological condi-tions in the site vicinity. The basic details of a moni-toring programme cannot be developed without knowl-edge of fundamental information on groundwater flowdirections, aquifer configuration and characteristics.Due to the high cost of typical groundwater investiga-tion programmes, monitoring and investigation objec-tives are often integrated so that boreholes serve bothpurposes as much as possible.

Specific objectives for investigation/monitoring in-clude:

• characterisation of the groundwater regime includ-ing pressures, flows and quality;

• identification and tracking of baseline conditionsover time;

• characterisation and tracking of effects of the landfillon groundwater;

• characterisation of the interactions of groundwaterwith surface waters; and

• characterisation of the interactions of leachate com-ponents with groundwater, migration pathwaysand attenuating effects likely in the groundwatersystem.


PARAMETERS UNITS MONITORINGFREQUENCY

Physico-chemical parameters Bi-annual/Annual

Alkalinity g/m3 ✔

Aluminium g/m3 ✔

Ammoniacal Nitrogen g/m3 ✔

Arsenic g/m3 ✔

Biological Oxygen Demand g/m3 ✔

Boron g/m3 ✔

Cadmium g/m3 ✔

Calcium g/m3 ✔

Chloride g/m3 ✔

Chromium g/m3 ✔

Chemical Oxygen Demand g/m3 ✔

Conductivity mSm-1 ✔

Dissolved Reactive Phosphorous g/m3 ✔

Total Hardness g/m3 ✔

Iron g/m3 ✔

Lead g/m3 ✔

Magnesium g/m3 ✔

Manganese g/m3 ✔

Nickel g/m3 ✔

Nitrate Nitrogen g/m3 ✔

pH ✔

Potassium g/m3 ✔

Sodium g/m3 ✔

Sulphate g/m3 ✔

Suspended Solids** g/m3 ✔

Silica g/m3 ✔

Total Kjeldahl Nitrogen g/m3 ✔

Total Organic Carbon g/m3 ✔

Zinc g/m3 ✔

Total Phenols g/m3 ✔

Volatile Acids g/m3 ✔

Volatile Organic Compounds g/m3 ✔

Semi-volatile Organic Compounds g/m3 ✔

Table 6.1: Example leachate monitoring programme for a regional landfill

Groundwater Drainage DischargeMonitoring

At sites where a groundwater drainage system is in-stalled beneath the liner, groundwater dischargeflowrate and quality need to be regularly monitored todetect any leachate contamination. This should formpart of the overall landfill monitoring programme.

In the first instance, monitoring could be for an indica-tor prevalent in leachate. If contamination is indicatedthen more detailed analysis is required to determine thecharacteristics of the contaminant.

Chemical parameters and characteristics that wouldgenerally be measured include:

• pH;


• conductivity;

• chloride; and

• ammoniacal nitrogen.

The results of regular sampling and analysis provide anaudit to ensure that the liner retains its integrity.

Design of a Groundwater MonitoringProgrammeMonitoring programmes for groundwater require theintegration of many factors that can influence the valueof the results obtained. Consideration needs to be givento:

• purposes of groundwater monitoring;

• specific objectives in relation to each purpose;

• integration of objectives to achieve efficiency andrationalised outcomes;

• selection of monitoring locations and target strata;

• monitoring well design;

• selection of suitable monitoring parameters;

• monitoring frequency;

• sampling methods and requirements;

• analytical detection limits;


• trigger levels.

Determining Numbers and Locations ofMonitoring PointsAppropriate positioning of monitoring points in agroundwater monitoring network is a key aspect of anymonitoring programme. Selection of well locationsneeds to consider the potential pathways for migrationof contaminants and travel rates. Degree of certainty inunderstanding the ground conditions affects the numberof wells. Complex hydrogeology normally requires alarger number of wells than simple, uniform condi-tions. Various analytical or computer analysis meth-ods can be applied to estimate the possible positions ofcontaminant plumes from landfills to assist in theselection of well locations (Haduk, 1998).

Sensitivity of the surrounding environment is an im-portant factor in monitoring well network selection. Inshallow aquifers with a water table where the environ-mental risk is low, a basic monitoring well systemcould comprise one well hydraulically upgradient, andthree wells hydraulically downgradient of the landfill.

For large-scale regional landfill facilities, 20 to 50monitoring/investigation wells may be required. As aminimum for landfill sites that cover only a small area,it is recommended that at least one upgradient and twodowngradient groundwater monitoring wells (possi-bly screened at different depths) be installed.

Key factors for selecting well sites include:

• potential sources and nature of contaminants withinthe landfill site, including refuse, transfer stationsand composting areas, if appropriate;

• sources of contaminants from external unrelatedactivities such as industry, farming and mining/quarrying;

• design of leachate retention systems;

• potential pathways for migration of contaminantsduring movement below ground;

• potential rate of travel along migration pathways;

• potential residence time of leachate species in thegroundwater system from source location to poten-tial receptor. Priority should focus on pathwaysections with residence times of less than 200years;

• changes to pathways and characteristics due toongoing landfilling or other new developments;and

• proximity of potential receptors along pathwaysand associated environmental/health risks.

Pathways for the movement of contaminants can beaffected by:

• the nature of the unsaturated zone;

• the presence of perched aquifers;

• fractured or porous aquifers;

• geological formation boundaries;

• bedding and tilting of strata;

• geological faults;

• groundwater divides;

• seasonal and short-term climatic influences; and

• neighbouring pumping wells.

The rate of movement of contaminants along the path-ways is controlled by four key hydrogeological param-eters that usually require field and laboratory testing inorder to be determined adequately:


• Hydraulic conductivity, K

— very slow K < 10-8m/s

— slow 10-6 > K > 10-8 m/s

— medium 10-4 > K > 10-6 m/s

— rapid K > 10-4 m/s;

• Effective porosity;

• Hydraulic gradient; and

• Soil/rock/leachate species interaction as given bythe Distribution Coefficient, Kd

— very mobile Kd < 1 ml/g

— mobile 100 ml/g > Kd > 1 ml/g

— immobile Kd > 100 ml/g.

Design Requirements for MonitoringWellsThe purpose of monitoring wells is to provide ‘repre-sentative’ samples of the groundwater in terms of itsphysical and chemical properties. Most wells are alsoused to monitor groundwater level. The design needsto consider the potential configuration and nature ofthe contaminants in the groundwater, the potential forchemical alteration of the samples and the samplingtechniques to be used.

Wells can use single or multiple monitoring facilities.Multilevel installations, where two or more casing/screen units are placed in the same borehole at differentlevels can offer cost savings, but introduce the risk ofcross-leakage. Post construction testing is necessary toconfirm the integrity of seals.

Well design should cover:

• Screen Length and Position. Screens are normally1 m to 3 m long. Longer screens loose detectionsensitivity to vertically variable water quality andprovide only a gross measure of contamination.Screens should be positioned on main flow path-ways and intersect the water table, where immisci-ble floating contaminants such as petrol, and somesolvents are likely to be found, if present.

• Casing and Screen Materials. Common practice isto use PVC materials due to their chemical andcorrosion resistance. Stainless steel is also suit-able. Joints should use mechanical connectionswithout the use of glues that can affect the sampleintegrity.

• Casing Diameter. 50 mm diameter casing meetscommon sampling and construction objectives.

Special sampling tools are available for smallerdiameters.

• Drilling and Construction Limitations. Drillingmethods need to be appropriate for the target zone(s)and soil/rock type, along with secure emplacementand sealing of screen sections. Wells should bedeveloped following construction to remove drill-ing fluid contaminants, clean the well and removefines from around screens.

• Filter Pack and Annular Seals for Screened Zones.Filter materials selected for packing screens shouldbe nonreactive to the groundwater environment.Geotextile sheaths can be appropriate for fine-grained formation materials but are susceptible toclogging and no data on the adsorption of organicsand other compounds is available. Annular sealsusing cement should not be used in screen zones toavoid leached residues from the cement impactingwater quality.

• Surface Completion. Security of the well head fromsurface water ingress and external damage areprime design considerations.

• Quality Assurance/Quality Control Procedures.Specifications for monitoring well constructionneed to cover quality requirements for materials,methods and testing to ensure satisfactory perform-ance of the completed well.

Monitoring ParametersContaminants that enter groundwater systems undergovarious degrees of transformation depending on theirchemical composition and the nature of the groundwaterenvironment. Factors such as soil/rock geochemistry,redox state, and background groundwater quality, canaffect the evolution of groundwater chemistry alongflow paths. Parameters selected for groundwater moni-toring programmes need to:

• characterise the overall background chemistry ofthe natural groundwater;

• characterise the range of contaminant sources likelyto be at the landfill; and

• be measured consistently, quickly and cost-effec-tively.

Generally, contaminants that move in groundwatersystems are in a dissolved form. Unless the stratacontain large openings such as sometimes occur infractured rock or dissolved cavity aquifers (for exam-ple, karst limestone aquifers), entrained solids in fluidcontaminants are filtered in the first layers of soil.However, some contaminants may be in pure liquid


form (such as petroleum products) beneath or floatingon the water table. Others, such as some metals, maymove by intermittently changing between solid anddissolved phases. In cavity flow systems, contami-nants can move by attachment to colloids or very finesediment.

The main focus is normally on parameters that aresoluble in the ambient groundwater at the site.

Table 6.2 contains a list of parameters that could bemeasured for a regional scale municipal solid wastelandfill. The list is by way of example and may needto be amended for specific situations according to thecharacteristics of the wastes in the landfill.

As a minimum, for small landfill sites, it is recom-mended that groundwater monitoring be undertakenfor the following, as leachate indicator parameters:

• water level;

• pH;

• conductivity;

• alkalinity;

• chloride;

• ammoniacal nitrogen;

• nitrate nitrogen, or total nitrogen;

• total organic carbon; and

• soluble zinc.

If the concentrations of these chemical parametersincrease by a significant amount, or show a trend ofincreasing concentration, then monitoring should becarried out for a more comprehensive suite of param-eters.

Monitoring Frequency and TimingDevelopment of specifications describing when andhow often samples should be taken, needs to be set inthe context of an overall monitoring strategy. Keyfactors that influence frequency and timing includethose discussed above that determine the positioning ofmonitoring wells. Other factors are:

• velocity of groundwater movement;

• regulatory requirements;

• operational factors such as landfill developmentstaging, and leachate, stormwater and gas control;and

• the cost and value of each data item within the

overall programme.

These objectives are normally achieved by a monitor-ing programme that has a tiered structure to provideinformation on the behaviour of the groundwater sys-tem and any contaminants within it, in a reliable andefficient manner. Each tier defines a parameter, timingand frequency suite that achieves a specific purposeaccording to the particular site conditions and require-ments. Most tiered systems will contain at least thefollowing basic elements:

• A baseline or pre-existing conditions tier.

• An indicator tier that tracks short-term behaviour.

• A comprehensive tier that tracks long-term changes.Sometimes this tier is split into two parts thatallows more costly measurements to be made on aless frequent basis.

• A contingency tier that is implemented followingabnormal results from the indicator tier. Generally,this tier results in the comprehensive tier beingundertaken on a more frequent basis while thecause is investigated and remedied.

The tiered system in Table 6.2 shows measurementsbeing taken on a fortnightly/monthly, quarterly/bi-annual and yearly basis. Actual monitoring frequencyshould be determined based on groundwater velocityand travel time to environmental receptors. This shouldensure that contaminants can be detected before reach-ing receiving environments.

Normally, there is no requirement for continuous moni-toring of groundwater, except perhaps if water levelsfluctuate daily in an irregular manner or if groundwateris being extracted under a contingency action follow-ing a contamination incident.

The timing of quarterly, six monthly and annual moni-toring rounds should consider seasonal groundwaterbehaviour to incorporate extremes in the variability ofparameter values. Co-ordination with the surface wa-ter monitoring programme is desirable where objec-tives are not compromised. This can achieve efficiencyand provide advantages in the assessment of interac-tions between the two types of water body.

As a minimum for small landfill sites, it is recom-mended that groundwater monitoring be undertaken atleast twice a year, to coincide with high and lowgroundwater levels.

Sampling and Analytical RequirementsThe capture of representative groundwater samples,and the achievement of a subsequent unbiased analysis


PARAMETERS UNITS MONITORING TIER

Baseline Indicator Comprehensive*

Fortnightly/Quarterly

Quarterly/Bi-annual

Yearly

Physico-chemical parameters

Water Level m ✔ ✔ ✔

Alkalinity g/m3 ✔ ✔

Aluminium g/m3 ✔ ✔

Ammoniacal Nitrogen g/m3 ✔ ✔ ✔

Arsenic g/m3 ✔ ✔

Boron g/m3 ✔ ✔

Cadmium g/m3 ✔ ✔

Calcium g/m3 ✔ ✔

Chloride g/m3 ✔ ✔

Chromium g/m3 ✔ ✔

Chemical Oxygen Demand g/m3 ✔ ✔

Conductivity mSm-1 ✔ ✔ ✔

Dissolved ReactivePhosphorous

g/m3✔ ✔

Total Hardness g/m3 ✔ ✔

Iron g/m3 ✔ ✔

Lead g/m3 ✔ ✔

Magnesium g/m3 ✔ ✔

Manganese g/m3 ✔ ✔

Nickel g/m3 ✔ ✔

Nitrate Nitrogen g/m3 ✔

pH ✔ ✔ ✔

Potassium g/m3 ✔ ✔

Sodium g/m3 ✔ ✔

Sulphate g/m3 ✔ ✔

Suspended Solids** g/m3 ✔ ✔ ✔

Silica g/m3 ✔ ✔

Total Kjeldahl Nitrogen g/m3 ✔

Total Organic Carbon g/m3 ✔ ✔

Zinc g/m3 ✔ ✔

Organic Screen

Total Phenols g/m3 ✔ ✔

Volatile Acids g/m3 ✔ ✔

Volatile Organic Compounds g/m3 ✔ ✔

Semi-volatile OrganicCompounds

g/m3 ✔ ✔

Notes:* this parameter list also applies for contingency monitoring** only where samples are not pre-filtered

Table 6.2: Example groundwater monitoring programme for a regional landfill


of results, can present considerable challenges forgroundwater monitoring programmes. A groundwatersample may be subjected to several different environ-ments and ambient conditions before it is analysed.Programmes need to recognise the physical and chemi-cal changes that can occur through the various stages ofsampling and analysis, and be tailored according to theobjectives for each sample. Often, the most sensitivespecies to be measured controls the approach andprotocols that are used.

A sampling programme should consider the followingfactors in its compilation:

• ambient conditions in the aquifer;

• location, condition and access constraints to sam-pling points;

• the range of parameters to be tested;

• number and frequency of samples;

• appropriate sampling protocols and equipment;

• sample field pre-treatment requirements includingfiltration and preservation;

• sample shipment to the analytical laboratory;

• sample documentation;

• sample chemical analysis protocols; and

• QA/QC requirements.

Factors that need to be taken into account in these stepsinclude:

• Sampling Methods and Equipment. Methods forsampling groundwater range widely and are con-tinually being improved. In general, the less distur-bance that a sample receives before capture in asample bottle, the more likely it is to retain itsintegrity. Some types of pumps, for example, mayrelease volatile components such as benzene fromthe sample, while others may draw in sediment bypumping too hard.

• Sample Collection Protocols. The well should bepurged of stagnant water before taking a sample.Normal practice is to purge three to five wellvolumes. Samples for trace metals analysis shouldnormally be field-filtered prior to placement in thesample bottle. In some cases, laboratory pre-filter-ing may be more practical if samples are highlyturbid and transit time to the laboratory is short.Micro-purging (Stone, 1997) is an alternativemethod, usually undertaken at pumping rates ofless that 1 L/min, that can avoid highly turbid

samples (and the need for pre-filtering) and largepurge volumes.

• Sample Storage and Transport. The use of labora-tory supplied bottles and transport containers isusually the most secure and quality-assured sampleholding method.

• Sample Analysis Protocols. Selection of analysismethods needs to consider factors including likelyparameter concentrations, detection limits, regula-tory requirements, and cost. More details of ana-lytical methods can be found in APHA (1998) .

• QA/QC Requirements. QA/QC requirements varydepending on elements of the monitoring pro-gramme. Some standardisation is possible butspecific plans are required for each site. Approxi-mately 10% to 15% of the sampling effort shouldbe devoted to QA/QC (ANZECC, 1992). Plansshould cover:

— cleaning and decontamination of samplingequipment;

— maintenance and calibration of instrumenta-tion;

— requirements for field blanks, bottle blanks, andreplicate samples;

— laboratory safeguards including reagent blanks,duplicates and reference materials;

— requirements for independent certification ofthe laboratory test method;

— checks by independent third parties; and

— checking of analysis results by comparisonwith previous measurements.

Detection LimitsA detection limit relates to the lowest level that aparticular method of analysis can detect a parameter99% of the time. Detection limits should be set withina sampling plan and be based on:

• the likely concentration range of the parameter inthe groundwater;

• applicable regulatory or performance standards,including trigger levels for the groundwater at thesite; and

• practical limitations of the sampling and analysisprocess.

Detection limits should be set in prior consultationwith the laboratory to ensure that the objectives of the


sampling can be met. Normally they should be set 10times or more below the applicable site standard toprovide clear indication of any adverse trends.

6.5 Surface Water Monitoring

Purpose of Surface Water MonitoringLandfill operations may present a range of adverseenvironmental effects and risks to surface waters,including water quality and aquatic biota. Surfacewater monitoring is a key tool to:

• warn of potential significant adverse environmen-tal effects on surface water resources;

• identify the need for mitigation and remediation;and

• check compliance with landfill operations and regu-latory requirements.

Leachate and sediment runoff pose the primary risks ofcontamination by landfills to surface waters. Overall,landfill operations with the potential to contaminatesurface waters include:

• sub-surface migration of leachate as a result ofnormal seepage or an accidental breach/failure ofthe landfill liner;

• discharge of sediments from the landfill as a resultof earthworks or structural failure;

• above-surface leachate break-outs or spills;

• other surface spills of hazardous substances; and

• other activities with the potential to contaminatesurface waters, for example discharge of vehicle ormachinery wash water.

Surface water monitoring programmes are usuallybased on a tiered strategy, according to the followingstructure:

• Baseline monitoring to establish the general statusof surface waters prior to commencement of, orchange to, landfill operations.

• Comprehensive monitoring to establish any changesto the general status of surface waters once landfilloperations have commenced/changed.

• Indicator monitoring based on selected key indica-tor parameters to provide rapid feedback on opera-tional processes and any problems such as a leachateescapes and excessive sediment runoff.

Prior to embarking on a surface water monitoring

programme, it is important to establish the objectivesfor surface water monitoring and to develop a monitor-ing plan. Both the objectives and the monitoring planare landfill and site-specific. The following sectionsprovide guidance on undertaking this process.

Controls for Surface Water MonitoringSurface water monitoring programmes need to becarefully designed. They must protect the receivingenvironment while enabling effective management ofthe landfill. They should also be designed to enable thereliable collection of information, to avoid the accu-mulation of redundant data, and to be cost-effective.

To be able to operate effectively, any surface monitor-ing programme must have controls in place. Theseinclude statistical reliability, temporal and spatial con-trols, and quality assurance and control (QA/QC) meas-ures, as follows:

• The design of a surface water monitoring pro-gramme must be based on statistical considera-tions. These must take into account the variabilityand accuracy of the data collected and their abilityto identify change and non-compliances.

• Temporal controls are normally in the form ofbaseline data. These are collected to document thestatus of surface water quality before landfill op-erations commence or change. They are used as abenchmark for evaluating changes in surface waterquality once the landfill is operating.

• Spatial controls are usually based on control sites.These are placed at an upstream location fromlandfill operations or in nearby, similar surfacewaters that are unaffected by landfill operations.Again, data collected from such sites serve asbenchmarks against which any changes in surfacewater quality resulting from landfill operations canbe evaluated.

QA/QC measures form an important part of any sur-face monitoring programme. They are based on suit-able procedures to ensure that monitoring data areaccurate and reliable.

Design of a Surface Water MonitoringProgrammeThe design of a surface monitoring programme forlandfill operations should take into account a numberof key considerations, including:

• the objectives of the monitoring programme;

• nature and location of hazards with the potential tocontaminate surface waters;


• selection of suitable monitoring points;

• selection of suitable monitoring parameters;

• monitoring frequency;

• sampling requirements;

• analytical detection limits;


• trigger levels.

Determining Locations for Stormwaterand Surface Water MonitoringLocations for a surface monitoring programme need tocover all surface water resources that could potentiallybecome contaminated by landfill operations. Key cri-teria that should be considered when selecting moni-toring stations include:

• potential sources of contamination associated withthe landfill and their above and below groundpathways;

• other external sources of contamination that mayaffect surface water resources;

• location of surface water sources, in particularsensitive environments;

• requirements for control site(s);

• extent of receiving water dilution and mixing; and

• site accessibility.

Parameters for Surface Water QualityMonitoringSurface water monitoring programmes require a rangeof parameters to be monitored. It is important thatparameters are carefully selected at the outset. Param-eters chosen for surface water monitoring programmesshould be able to:

• adequately describe the overall status of surfacewaters, including water/sediment quality and aquaticecology;

• reliably pick up contaminants discharged from thelandfill or other relevant sources; and

• be measured consistently, quickly and cost-effec-tively.

Physico-chemical Water Quality

Table 6.3 provides a list of water quality parametersthat are typically included in a surface water monitor-

ing programme for a regional landfill, including pa-rameters for baseline, comprehensive and indicatormonitoring.

While the list is representative, it needs to be reviewedfor different landfill operations and locations. Forsmaller landfills, some parameters may be omitted.Conversely, for a regional landfill that receives largequantities of treated hazardous waste, specific param-eters may need to be added.

Sediment Quality

Monitoring of sediment quality may be necessary forthose landfills located in the vicinity of depositingsurface water environments such as slow-flowing riv-ers, lakes or estuaries. In these environments, certaincontaminants with an affinity to particulate matter mayaccumulate in sediments, particularly trace metals andorganic constituents. Table 6.3 lists the parametersthat are appropriate for inclusion into a sediment moni-toring programme.

Biological Quality

The monitoring of aquatic biological parameters maybecome necessary for those landfills located in thevicinity of sensitive and/or valuable surface waterenvironments. A number of biological parameters canbe monitored, including aquatic plants (emergent andsub-surface, higher and lower plants), fish and benthicinvertebrates (bottom-dwelling lower animals).

Mostly, biological parameters are used for baseline orcomprehensive monitoring to describe the generalstatus of surface water resources. They are less suitablefor indicator monitoring because of their high inherentlevel of variability and associated high sampling andanalytical costs. Further, destructive sampling meth-ods may contribute to the degradation of biologicalindicators that are monitored.

Overall, the need for biological monitoring needs to beevaluated carefully for each landfill operation andlocation, based on the above considerations. In mostcases, specialist technical expertise is needed to ensurethat biological sampling and data analysis is carried outin a competent and reliable manner.

Whole Effluent Toxicity Testing

Whole Effluent Toxicity (WET) tests are commonlyused in the US to test the toxicity of effluents to selectedaquatic organisms. WET tests enable the assessmentof complex mixtures of chemicals on the environment.

The application of WET tests in landfill surface watermonitoring programmes in New Zealand has been


PARAMETERS UNITS MONITORING TIER

Water Quality SedimentQuality

Baseline Indicator Comprehensive

Continuous FortnightlyMonthly

QuarterlyBi-annual

Yearly Yearly

Physico-chemical parameters

Flow l/s ✓ ✓ ✓

alkalinity g/m3 ✓ ✓

Aluminium (TOT/AS) g/m3 ✓ ✓ ✓ ✓

Ammoniacal Nitrogen g/m3 ✓ ✓ ✓

Arsenic (AS) g/m3 ✓ ✓ ✓ ✓

Boron g/m3 ✓ ✓

Cadmium (AS) g/m3 ✓ ✓ ✓ ✓

Calcium g/m3 ✓ ✓

Chloride g/m3 ✓ ✓ ✓

Chromium (AS) g/m3 ✓ ✓ ✓ ✓

Chemical Oxygen Demand g/m3 ✓ ✓ ✓

Conductivity mSm-1 ✓ ✓ ✓ ✓

Copper (AS) ✓ ✓ ✓ ✓

Dissolved ReactivePhosphorous

g/m3 ✓ ✓

Total Hardness g/m3 ✓ ✓

Iron (TOT/AS) g/m3 ✓ ✓ ✓ ✓ ✓

Lead (AS) g/m3 ✓ ✓ ✓ ✓

Magnesium g/m3 ✓ ✓

Manganese (TOT/AS) g/m3 ✓ ✓ ✓ ✓

Nickel (AS) g/m3 ✓ ✓ ✓ ✓

Nitrate Nitrogen g/m3 ✓ ✓

pH g/m3 ✓ ✓ ✓

Potassium g/m3 ✓ ✓

Sodium g/m3 ✓ ✓

Sulphate g/m3 ✓ ✓

Suspended Solids g/m3 ✓ ✓ ✓

Temperature g/m3 ✓ ✓

Total Kjeldahl Nitrogen g/m3 ✓ ✓ ✓

Total Organic Carbon g/m3 ✓ ✓ ✓

Turbidity NTU ✓ ✓ ✓

Zinc (AS) g/m3 ✓ ✓ ✓ ✓ ✓

Organic Screens

Total Phenols g/m3 ✓ ✓

Volatile Acids g/m3 ✓ ✓

Volatile Organic Compounds g/m3 ✓ ✓ ✓

Semi-volatile OrganicCompounds

g/m3 ✓ ✓ ✓

Biological Parameters

Aquatic Biota ✓ ✓ ✓

WET ✓

Table 6.3: Example surface water monitoring programme for a regional landfill


limited to date, as leachate is rarely discharged directlyto the environment. Although WET protocols havebeen used to test receiving water toxicity in surfacewaters below landfills with leachate irrigation sys-tems, the effectiveness of such testing is limited due tothe high variability of receiving waters and the currenthigh costs of WET tests.

Monitoring Frequency and TimingThe requirements for the frequency and timing ofsurface water monitoring varies between landfills,depending on:

• landfill layout and operations;

• sensitivity of the receiving environment; and

• variability of the receiving environment.

Frequency and timing of surface water monitoringvary from landfill to landfill, depending on location,size, operations and environmental risks or events(such as heavy rainfall or flooding). For example,where leachate is treated and irrigated on-site or in thevicinity of sensitive surface water resources, surfacewater monitoring should be more frequent. Require-ments for monitoring frequency may be reduced overtime if a high level of landfill performance can bedemonstrated.

Monitoring frequency and timing must also take intoaccount the variability of the receiving environmentthrough time and space, such as high and low tides inestuarine/marine environments, seasonal low and highflows in rivers, or daily water quality changes in lakes.Therefore, monitoring needs to reflect the spectrum ofenvironmental change and, as a minimum, worst caseconditions. Worst case conditions are represented byextreme conditions where the risk of adverse environ-mental effects is high, such as during low flow or hightemperatures.

To optimise monitoring efforts and costs, surface wa-ter monitoring strategies are often based on a tieredapproach where monitoring frequency and timing vary.Table 6.4 outlines an example of a tiered monitoringstrategy for surface waters.

Sampling and Analytical RequirementsAs part of implementing a surface water monitoringstrategy, a sampling plan is required. This plan needsto specify:

• a schedule for sampling locations, parameters, fre-quency and timing;

• sampling and analytical protocols;

• requirements for sample handling, preservation,processing, transport and storage; and

• QA/QC requirements.

The sampling schedule also needs to specify the number(replicates) of samples to be collected at any time.Ideally, the number of samples is determined by anacceptable level of uncertainty specified at the 95%confidence level. However, due to the high costsincurred by replication, this guideline is seldomachieved. Rather, the approach taken to reduce theuncertainty of monitoring data is to average them overtime or space.

Sampling and analytical protocols should specify themethods used for visual observations, field measure-ments, sample collection and analytical testing. Thereare a number of references that may be used for thispurpose, including APHA (1991), Hellawell (1978),Metcalfe-Smith (1992) and Standards Association ofAustralia (1987). A full range of references is providedin ANZECC (1992). Protocols must be passed on toexternal contractors involved in the monitoring pro-gramme.

Sampling protocols also need to address sample han-dling, preservation, processing, transport and storage.It is beyond the scope of this document to go intodetails, but a range of references may be used for thispurpose (see Bibliography).

Processing of water samples for trace metal analyses isan issue that has received specific attention over recentyears. As metals have an affinity to adsorb to particulatematter, they tend to be only partially available toaquatic organisms and therefore exhibit only limitedtoxicity. Historically, the trend has been to measuremetals using total extraction techniques. Recentrecommendations by the USEPA indicate that onlysoluble metals need to measured. However, the prac-tice in New Zealand over recent years has been to adoptacid-soluble processing techniques, where trace met-als adsorbed to sediments are partially extracted by aweak acid prior to analysis.

The sample plan also needs to outline a series of QA/QC protocols, specifically relating to:

• maintenance and calibration of field instrumenta-tion;

• use of field and bottle blanks to verify sampling andbottle cleanliness;

• use of reagent blanks, duplicates, known additionsand references material by laboratories involved inanalytical testing;


• use of independently certified contractors (for ex-ample, Telarc registered laboratories); and

• checks by independent third parties.

Approximately 10% to 15% of the total effort of asurface water monitoring programme should be de-voted to QA/QC (USEPA, 1992). All QA/QC protocolsand results should be documented in a manner thatenables them to pass regulatory authority scrutiny.

Detection LimitsDetection limits refer to the level that a measurementor an analysis of a monitoring parameter must achieve.The setting of detection limits is usually based on thefollowing criteria:

• the ability to provide useful information for man-agement purposes;

• applicable environmental performance standards

or trigger levels (as a rule, detection limits shouldbe set an order of magnitude lower than applicabletrigger levels); and

• practical limitations, such as the reliability of anobserver, or the sensitivity of an instrument or ananalytical analysis.

Detection limits for surface water monitoring pro-grammes must be determined at the outset, and anyexternal parties, such as analytical laboratories, mustbe advised. This enables data to be collected andevaluated in a consistent and standard manner.

6.6 Analysis and Review ofMonitoring Data

GeneralMonitoring data from landfill sites needs to be collated,reviewed and analysed to:

Monitoring Tier Frequency/Description ofParameters

Purpose

Baseline Monthly to quarterly monitoring of general water and sedimentquality (refer Table 6.3) andbiological parameters

Establish the status of existing surface waterresources at selected monitoring stationsbefore commencement or a change inlandfill operations

Indicator

Continuous record of flow

Automatic flow meter installed at one ormore stations to record catchment andlandfill runoff and identify the need for flow-related controls

Continuous record of conductivity

Automatic meter installed at one or morestations to pick up any escapes of leachateto surface waters

Continuous record of turbidity

Automatic meter installed above and/orbelow stormwater ponds to check treatmentefficiency and measure compliance

Daily visual inspectionsVisual inspection of stormwater controlsystems and surface waters downstream oflandfill

Fortnightly water quality sampling (refer Table 6.3)

Short list of parameters aimed at checkinggeneral water quality and picking upleachate contaminants

ContingencyLong list of parameters to be sampled onlywhen indicator monitoring data indicatesregulatory exceedence

ComprehensiveQuarterly sampling (refer Table 6.3)

Long list of parameters checking generalwater quality and a wide range of possiblecontaminants (some parameters used as forbaseline monitoring)

Yearly samplingSelected parameters including organicscreening tests, sediment and biologicalsampling, WET tests (optional)

Table 6.4: Example surface water

monitoring strategy


• establish baseline conditions;

• track changes to baseline conditions in relation tosite activities, climatic and external factors;

• provide a basis for interpretation of overallgroundwater and surface water behaviour and ef-fects over time;

• check compliance against site performance stand-ards and resource consent requirements;

• provide information for reporting to regulatoryauthorities;

• reviewing QA/QC information;

• process and storage of data (preferably usingcomputer software); and

• prepare monitoring reports.

Analytical methods applied to the data should takeaccount of:

• the purpose of the analysis;

• the form, precision and spread of the data;

• the validity of the method and its professionalacceptance; and

• the form and ease of interpretation of the results.

Leachate

Leachate monitoring data from landfill sites needs tobe analysed to:

• establish leachate volume produced;

• track changes in leachate strength; and

• determine if additional parameters should be addedto, or removed from, groundwater and surfacewater monitoring programmes.

GroundwaterData from groundwater monitoring usually has bothspatial and temporal components. Interpretation ofspatial data involves assessment of conditions through-out the zone of interest based on the available measure-ment points. In the first instance, interpolation needsto be limited within zones of hydrogeological similar-ity, taking account of features such as faults, strataboundaries and hydraulic conductivity conditions.Common methods of interpolation include contouringand kriging. Numerical groundwater flow and trans-port models can be used for complex situations.

Temporal analysis can involve simple time-series plotsor more detailed statistical analysis. There are a numberof methods and tools that can be used, depending on theanalysis objectives and complexity of the data. Mostcomputer spreadsheet programs will perform regres-sion and variance-type analyses.

For contaminant detection, assessment tests of statisti-cal significance are used. These assist in determiningwhether a data set shows evidence of contamination ornatural variability. Packages such as GRITS/STAT(USEPA, 1992) or general statistics type packages (egSYSTAT ) can be used. A discussion of methods isgiven in Neilson (1991) and Lachance and Stoline(1995).

Surface WaterStatistical methods should be applied to surface watermonitoring data to:

• examine data variability;

• evaluate the significance of adverse environmentaleffects; and

• determine compliance with trigger levels.

A detailed description of statistical methods availableto evaluate surface water monitoring data exceeds thescope of this document. However, a range of statisticalterms are used to describe the variability of monitoringdata, including means, medians, standard deviationsand percentiles. Similarly, there is a range of statisticalmethods to test the significance of the difference be-tween groups of data (for example, the difference inwater quality between an upstream and a downstreammonitoring location).

In applying statistical tests, care must be taken to checkwhether monitoring data is normally distributed or not.This will determine whether parametric or non-para-metric tests need to be applied. Suitable computersoftware to undertake such tests includes EXCEL

and SYSTAT . Useful references include McBride(1998), Ward et al. (1990), Keith (1988) and Sanders etal. (1983).

Trigger LevelsTrigger levels consist of specified numerical values ornarrative descriptors for the protection of groundwaterand surface water resources that must be met by thelandfill.

Trigger levels can be used:

• by landfill operators for operational purposes; and

• by consent authorities to set regulatory limits.


Landfill operators will normally set triggers on param-eters that have been set by the consent authority, but atlower levels to provide early warning of possiblecompliance issues. Other parameters relevant to theiroperational requirements are often measured also.

In New Zealand, a common approach is to adopt a two-tier trigger level system for surface water monitoringregimes. The first tier (TL1) has a mainly landfill-management related function. It is designed to alertmanagement to the fact that the landfill is about todeviate from normal operating conditions and is lead-ing to regulatory non-compliance. Therefore, TL1levels serve as an indicator of landfill operations formanagement purposes only.

Exceedance of the TL1 trigger level requires a speci-fied response to investigate the cause of the exceedanceand to remedy/mitigate the cause as necessary. TL1trigger levels are normally set at a specified level orpercentage of the regulatory binding TL2 trigger levelthat is suitable for management purposes — for exam-ple at 70% of the TL2 level.

The second tier of trigger levels (TL2) consists ofregulatory binding environmental performance stand-ards. Exceedance of a TL2 trigger level indicates non-compliance with the resource consent conditions im-posed on the landfill.

Groundwater

Trigger levels provide warning that something is hap-pening in the groundwater system that is abnormal andshould be investigated. Where data from monitoringrounds are normally fully collated and analysed sixmonthly or yearly, trigger levels provide a ready com-parator to test for any problems from each round ofmonitoring.

Trigger levels set for the detection of effects from thelandfill activities are usually compiled from an assess-ment of the natural baseline conditions. Where thebaseline conditions vary uniformly and can be de-scribed statistically by a normal distribution, the base-line for any parameter can be set as an envelope withinsome number of standard deviations from the meanvalue. Three standard deviations from the mean areused by some regulatory authorities which relatesapproximately to the 95% confidence level.

Trigger levels may also reflect drinking water or aquaticlife standards (e.g. Ministry of Health (1995) orANZECC (1992)) as appropriate for the likely down-gradient use of the groundwater.

Surface Water

Performance standards form the basis to determine

compliance of landfill operations with operational andresource consent requirements for surface waters.

For surface monitoring programmes, TL2 trigger lev-els are usually based on:

• national/international criteria for the protection ofaquatic life (for example, USEPA (1991) orANZECC (1992));

• average background levels established for controlsites (usually based on the mean plus three timesthe standard deviation [x + 3 x STD] ); and

• visual controls, such as photographs and maps.

To be able to evaluate compliance of monitoring datawith surface water performance standards or triggerlevels, it is necessary to specify what an exceedance is.Examples are listed below.

• For continuous (i.e. half-hourly) measurements ofturbidity and conductivity, compliance with triggerlevels can be assessed by using running averagescalculated over 12 successive measurements (i.e. 6hours total).

• For fortnightly monitoring data, compliance can beassessed using running averages over three succes-sive sampling occasions. Also, non-compliancecan be deemed to have occurred if more than one ofthe three data points exceeds the trigger level.

• For quarterly and annual monthly monitoring data,compliance with trigger levels can be assessedusing individual data points.

6.7 Landfill Gas Monitoring

Purpose of Landfill Gas MonitoringMonitoring of landfill gas is important to enable effec-tive management of on-site and off-site risks. Onlandfills operating active gas extraction systems, thesurface and sub-surface monitoring results also pro-vide supplementary information for the effective op-eration of the extraction system. Monitoring resultsprovide the ability to:

• determine the effectiveness of landfill gas controlmeasures and identify any requirements for modi-fication;

• permit a gas field to be “tuned” effectively toprovide optimum gas control;

• determine the extent of landfill gas migration offsite;

• identify migration pathways;


• assess risks to neighbouring properties; and

• assess the fire risk potential of the landfill gas bothwithin and outside the refuse.

Characteristics Affecting MonitoringRequirementsThe nature and frequency of landfill gas monitoring isgoverned by a number of site parameters including:

• landfill size;

• refuse type and age;

• surrounding land use;

• site geology and groundwater conditions;

• landfill gas control measures in place; and

• results from previous monitoring.

Subsurface Gas MonitoringWhere developments are within 250 metres of a landfillsite, or underlying geology makes migration likely,landfill gas should be monitored using installed probesaround the site boundary. As a preliminary assess-ment, and to assist the siting of monitoring probes, itmay be useful to conduct a gas spiking survey aroundthe landfill site boundary. Spiking surveys involvecreating holes in the ground and measuring gas con-centrations via a tube inserted into the hole (with a sealaround tube at top of hole made during sampling).Spiking surveys are only of limited use if gas migrationat depth is occurring.

Permanent monitoring probes should consist of a lengthof pipe made from an inert material such as PVC witha perforated section over the required sampling length.The pipe is usually installed in a gravel pack andappropriately sealed over the upper one metre. Asampling point should be installed in the capped top ofthe probe to enable measurement of landfill gas with-out having to open the sampling probe. Probe depthsshould generally be at least 3 metres, although deeperprobes may be required in areas of low groundwatertables, where deep unsaturated permeable layers/fis-sures exist, or refuse depths are high and water levelslow.

At some sites it may be necessary to install stackedprobes, which incorporate several pipes with screens atdiscrete depths (corresponding to differing strata/fis-sures) with seals between each screen.

Monitoring of the probes is preferable during low andfalling barometric pressures as these conditions pro-vide closer to “worst case” results in terms of gasmigration. A systematic procedure should be used for

monitoring the probes to ensure consistency and shouldinclude:

• recording barometric pressure and ground pres-sure; and

• measurement of concentrations of methane, carbondioxide and oxygen, purging the probe of at leasttwice the probe volume using an intrinsically safevacuum pump to provide a representative gassample.

The probe should remain sealed between monitoringperiods. Opening of the probe cap (to obtain watertable levels, etc.) should only be done at the completionof a monitoring procedure.

The number and locations of monitoring probes de-pends on a number of site parameters as listed earlier.Probe spacing and depths will be site specific andshould be determined only after a detailed review ofsite conditions by specialists in the field of landfill gasmonitoring.

Monitoring Frequency

Probe monitoring frequencies will vary depending onsite circumstances. Where site conditions change (e.g.extraction rates, surrounding landuse, water table), thefrequency of monitoring should be increased until gasconcentrations are found to stabilise.

As a minimum, monitoring of each probe should becarried out six monthly until probe gas concentrationshave stabilised below 1% by volume methane and1.5% by volume carbon dioxide.

In the absence of buildings within 250 metres of thelandfill boundary, the USEPA guidance value, abovewhich gas control is required, is 5% methane in aboundary probe.

More frequent monitoring will be required where gasis found in close proximity to properties. In the case ofresidential properties, permanent gas monitoring equip-ment may be necessary.

Surface Gas MonitoringSeveral techniques exist for monitoring surface emis-sions from a landfill. It is unlikely that all techniqueswill be required for any one landfill, however they havebeen listed below for completeness:

• Visual Inspection — although not adequate in itselfas a means of monitoring, visual inspection canprovide useful information as to potential areas ofelevated landfill gas emissions. Key indicators areareas of distressed vegetation, evidence of cappingcracking and discernible landfill gas odours. Find-


ings from a visual inspection should be confirmedusing instantaneous surface monitoring.

• Instantaneous surface monitoring (ISM) — an ISMis conducted over a prescribed or random walkpattern across a site using a flame ionisation detec-tor (FID). Methane is sampled via a wand with afunnelled inlet held 50 mm to 100 mm above theground surface. Site conditions should be dry andwind velocities less than 15 km/hr on average.During the monitoring process the technician makesrecordings at regular intervals and includes anyareas of elevated emission levels.

• Integrated surface sampling (ISS) — an ISS issimilar to instantaneous surface monitoring withthe exception that gas collected during the walkpattern is pumped to a non-contaminating samplebag. The methane reading in the bag can then bemeasured, giving an average concentration overthe walk pattern. Trace constituents can also bemeasured from the gas sample. Extreme care isrequired using this system in order to obtain repre-sentative results.

• Ambient Air Sampling — ambient air up-wind anddown-wind of a site is collected via integratedambient air samplers into non-contaminating bags.This form of sampling is usually focused on meas-uring total non-methane hydrocarbons and tracepollutants and is likely to be required only inexceptional and specific circumstances.

• Flux Box Testing — flux boxes are containers(typically drums cut lengthways) with the open endembedded approximately 2 cm into the landfillsurface. A small hole is formed in the side of thecontainer to allow venting. A flux box testingprogramme requires a specific design to ensure thata dependable outcome is achieved.

Where surface emissions may present a risk to a site, orcreate an odour nuisance, visual inspections and ISMsurveys should be carried out to assess areas requiringremedial work. Other techniques may be utilised inspecific situations. For sites with active gas extraction,ISM results can also provide useful information foroptimising the effectiveness of the extraction systemand capping maintenance.

Monitoring in BuildingsWhere a building is determined to be at potential risk,based on probe monitoring results or other monitoringinformation, the building should be regularly monitor-ing to check for the presence of landfill gas. During themonitoring, a portable gas sampler should be used tomeasure methane and carbon dioxide concentrations in

all voids and areas in the basement and/or ground floorand wall cavities of the building. If possible, measure-ments should be made in each location before allowingventilation to occur (e.g. measure under a door beforeopening).

If landfill gas is detected, the cause should be remediedas soon as practically possible. Generally, if methanein excess of 10% LEL is detected, gas control measureswill be required. If concentrations are found to exceed1% by volume methane or 1.5% by volume carbondioxide, the building should be evacuated, all ignitionsources (including electricity) switched off, and reme-dial work carried out as soon as possible under anapproved health and safety plan prior to reoccupation.

Monitoring frequencies will vary depending on thelevel of risk to the building and/or occupiers. Gener-ally monitoring should be carried out at least every sixmonths and stopped only if risks can be demonstratedto be low. For higher risk situations it is advisable toinstall a permanent gas monitor, an alarm system, andto establish clear protocols in the event of an alarmactivating.

Landfill Gas Control System MonitoringWhere landfill gas is actively collected and flared, and/or removed from site for utilisation, monitoring of thesystem is necessary to ensure:

• air is not sucked into the landfill, creating thepotential for an underground fire;

• gas quality is appropriate for the flaring system orend use;

• gas is flared at an adequate destruction efficiency(where a flare is used);

• there is adequate control to permit areas of the siteto be isolated or gas extraction rates adjusted; and

• condensate from the gas extraction system is ad-equately managed.

Monitoring requirements will be specific to the designof the control system. However, monitoring for thefollowing parameters should generally be undertakenat each well head, or combination of well heads, and atall flare or gas utilisation facilities:

• gas pressure;

• gas flow;

• methane;

• carbon dioxide;

• oxygen;


• residual nitrogen (by calculation);

• temperature (as an indicator of landfill fire); and

• carbon monoxide (as an indicator of landfill fire).

Monitoring frequency should be as frequent as possi-ble and ideally weekly. However monthly monitoringis commonly adopted once a gas field has been “tuned”(adjusted to a stable condition).

In addition, monitoring of hydrogen sulphide and non-methane organic compounds (NMOCs) may need to beundertaken to check for total NMOCs emissions.

FlaresThere are two common types of flare used, candle(open flame) flares and ground flames. Ground flaresprovide a significantly higher level of gas combustioncontrol capability. Both types of flare station must befitted with appropriate safeguards to prevent flameflashback or ignition of the incoming gas stream.Typically these safeguards will include:

• a flame arrestor;

• an automatic slam-shut isolation valve; and

• an oxygen sensor.

It is usual for the oxygen sensor to alarm at between 4%to 6% oxygen (depending on gas control requirements)and automatically shutdown the extraction system.

Candle flares are typically monitored for methane flowrate and oxygen on the incoming gas contents. Thereare usually no specific combustion controls other thanflame outage monitoring equipment.

Ground flares usually have facilities to measure meth-ane flow rate and oxygen on the incoming gas, com-bustion temperature monitoring and also facilities forhigh temperature gas sampling.

It is important that all flare stations comply with theappropriate hazardous area classifications in terms ofall electrical and control equipment installed.

ReferencesANZECC, 1992. Australian Water Quality Guidelines

for Fresh and Marine Waters. Australia andNew Zealand Environment and ConservationCouncil.

APHA, 1998. Standard Methods for the Examinationof Water and Wastewater. 20th edition. Ameri-can Public Health Association, Washington.

Haduk P F, 1998. “A method for designing configura-tions of nested monitoring wells near landfills”.Hydrogeology Journal (1998) 6:341-348.

Hellawell, J M, 1978. Biological Surveillance ofRivers. Water Research Centre, Stevenage,United Kingdom.

Keith, L H (Editor), 1988. Principles of EnvironmentalSampling. ACS Professional Reference Books,American Chemical Society.

Lachance A D and M R Stoline, 1995. “The applicationof a statistical trend analysis model to groundwater monitoring data from solid wastelandfills”. Ground Water Monitoring andRemediation, Vol XV No 4.

McBride G, 1998. “When differences are equivalent”.Water and Atmosphere Vol. 6 No.4. NationalInstitute of Water and Atmospheric Research,Christchurch, New Zealand.

Metcalfe-Smith, 1992. “Biological water quality as-sessment of rivers based on macroinvertebratecommunities”. In: Rivers Handbook, edited byCalow, P and Petts, G E. Blackwell ScientificPublications, Oxford.

Ministry of Health, 1995. Drinking Water Standardsfor New Zealand.

Nielson David M (ed.) 1991. Practical Handbook ofGround-Water Monitoring. Lewis Publishers

Sanders T G, Ward J C, Loftis T D, Steele T D, AdrianD D and V Yevyevich, 1983. “Water qualitymonitoring - a systems and stochastic perspec-tive”. In: Design of Networks for MonitoringWater Quality. Water Resources Publications,Lyttleton.

Standards Association of Australia, 1987. AS2031 –The Selection of Containers and Preservationof Water Samples for Chemical and Microbio-logical Analyses. Standards Association ofAustralia, Canberra.

Stone W J, 1997. “Low flow ground water sampling –is it a cure-all?” Groundwater Monitoring andRemediation, Vol XV11 No 2

United States Environmental Protection Agency 1991.Water Quality Criteria.

USEPA ,1992. A Ground Water Information TrackingSystem with Statistical Analysis CapabilityGRITS/STAT v4.2. US Environmental Protec-tion Agency, Office of Research and Develop-ment, Office of Solid Waste, and Region VII.EPA/625/11-91/002.


Ward, R C, Loftis, J C and McBride, G B 1990. Designof Water Quality Monitoring Systems. VanNostrand Reinhold, New York.

Glossary • 85

Glossary

Aquifer

A geologic formation or layer of rock or soil that isable to hold or transmit water.

Background Level

Ambient level of a contaminant in the local area ofthe site under consideration.

Bio-accumulation

Accumulation within the tissues of living organ-isms.

Cleanfill

A cleanfill is any landfill that accepts only cleanfillmaterial and inert wastes, including clean exca-vated natural materials.

Cleanfill Material

Material that when discharged to the environmentwill not pose a risk to people or the environment,and includes natural materials such as clay, soil,rock and such other materials as concrete, brick ordemolition products that are free of:

• combustible, putrescible or degradable compo-nents;

• hazardous substances or materials (such asmunicipal solid waste) likely to create leachateby means of biological breakdown;

• any products or materials derived from hazard-ous waste treatment, stabilisation or disposalpractices;

• materials such as medical and veterinary waste,asbestos or radioactive substances that maypresent a risk to human health if excavated; and

• contaminated soil and other contaminated ma-terials.

Closed Landfill

Any landfill that no longer accepts waste for dis-posal.

Co-disposal

The disposal of hazardous waste by mixing in aninformed and predetermined manner, with munici-

pal refuse, so as to use the attenuation and bio-chemical processes operating within the landfill toreduce the environmental impact from the mixedwaste to an insignificant level.

Contaminant

Any substance (including gases, liquids, solids,and microorganisms) or energy (excluding noise)or heat, that either by itself or in combination withthe same, similar, or other substances, energy orheat:

a) when discharged into water, changes or is likelyto change, the physical, chemical or biologicalcondition of water; or

b) when discharged onto or into land or into air,changes or is likely to change, the physical,chemical or biological condition of the land orair onto or into which it is discharged.

Corrosivity

The ability of a substance to corrode metals or tocause severe damage by chemical action when incontact with living tissue.

Discharge

Includes emit, deposit and allow to escape.

Discharge Permit

A consent to do something that otherwise wouldcontravene section 15 of the RMA.

Ecosystem

A dynamic complex of plant, animal and micro-organism communities and their non-living envi-ronment, interacting as a functional unit.

Ecotoxicity

Adverse toxic effects on ecosystems or ecologicalcommunities.

Environment

Includes:

• ecosystems, including people and communi-ties: and

• all natural and physical resources; and


• those qualities and characteristics of an areathat contribute to the community’s reasonableenjoyment; and

• the cultural, economic, aesthetic, and socialconditions that affect the above.

Flammability

The ability of a substance to be ignited and tosupport combustion.

Geomembrane

A polymeric sheet material that is impervious toliquid as long as it maintains its integrity.

Geosynthetic Clay Liner (GCL)

A relatively thin layer of processed clay (typicallybentonite) either bonded to a geomembrane orfixed between two sheets of geotextile.

Geotextile

A woven or non-woven sheet material less imper-vious to liquid than a geomembrane, but moreresistant to penetration damage.

Hazardous Waste

Hazardous waste is waste that poses a present orfuture threat to people or the environment as a resultof one or more of the following characteristics:

• explosiveness;

• flammability;

• capacity to oxidise;

• corrosiveness;

• toxicity; and

• eco-toxicity.

Hazardous Waste Landfill

A hazardous waste landfill is any landfill thataccepts waste formally defined as "hazardous waste"in statutory instruments or as specifically deter-mined through any special requirements that maybe set by the Environmental Risk ManagementAuthority (ERMA).

Industrial or Trade Premises

• Any premises used for industrial or trade pur-poses; or

• Any premises used for the storage, transfer,treatment or disposal of waste materials or for

other waste management purposes, or used forcomposting organic materials; or

• Any other premises from which a contaminantis discharged in connection with any industrialor trade process and includes any factory farm,but does not include production land.

Industrial Waste

Industrial waste is that waste specific to a particularindustry or industrial process. It typically containssomewhat higher levels of contaminants (up to fourtimes), such as heavy metals and human-madechemicals, than municipal solid waste and needs tobe managed with environmental controls appropri-ate to the specific waste(s) being landfilled.

Industrial Waste Landfill

An industrial waste landfill is a landfill that isdesigned to accept predominantly industrial waste.

Land Use Consent


Landfill

A waste disposal site used for the controlled depositof solid wastes onto or into land.

Landfill Gas

Gas generated as a result of decomposition proc-esses on biodegradable materials deposited in alandfill. It consists principally of methane andcarbon dioxide, but includes minor amounts ofother components.

Leachate

The liquid effluent produced by the action of waterpercolating through waste, and that contains dis-solved and/or suspended liquids and/or solids and/or gases.

Municipal Solid Waste

Municipal solid waste is any non-hazardous, solid,degradable waste from a combination of domestic,commercial and industrial sources. It includesputrescible waste, garden waste, uncontaminatedbiosolids and clinical and related waste. All mu-nicipal solid waste shall have an angle of repose ofgreater than five degrees (5) and have no freeliquids.

Municipal Solid Waste Landfill

A municipal solid waste landfill is any landfill thataccepts municipal solid waste.

Glossary • 87

Oxidise

In relation to a capacity to oxidise, the ability of asubstance to cause or contribute to the combustionof other material by yielding oxygen.

Resource Consent

A coastal permit, discharge permit, land use con-sent or water permit.

Biosolids

The semi-liquid residue from sewage treatmentplants, septic tanks and the processing of organicmaterials.

Toxicity

The adverse effects caused by a toxin (poison) that,when introduced into or absorbed by a living organ-ism, destroys life or injures health. Acute toxicitymeans the effects that occur a short time followingexposure to the toxin, and chronic toxicity meansthe effects that occur either after prolonged expo-sure or an extended period after initial exposure.

Transfer Station

A facility where wastes are transferred from smallervehicles (cars, trailers, trucks) into larger vehiclesfor transport to a disposal site.

Treatment

In relation to wastes, any physical, chemical orbiological change applied to a waste material priorto ultimate disposal, in order to reduce potentialharmful impacts on the environment.

Waste

Any contaminant, whether liquid, solid, gaseous, orradioactive, which is discharged, emitted or depos-ited in the environment in such volume, constitu-ency or manner as to cause an adverse effect on theenvironment and which includes all unwanted andeconomically unusable by-products at any giventime, and any other matter which may be discharged,accidentally or otherwise, into the environment.

Water Permit


Bibliography • 89

Bibliography

IntroductionMinistry for the Environment (MfE) (November 1992).Landfill Guidelines including Landfill EngineeringGuidelines produced by the Centre for Advanced En-gineering, University of Canterbury, New Zealand.

New South Wales Environmental Protection Author-ity (1996). Environmental Guidelines: Solid WasteLandfills, Australia.

Landfills and LegislationMinistry for the Environment (MfE) (1994). Wasteand the RMA.

Resource Management Act (1991).

Landfill SitingDepartment of Urban Affairs and Planning (DUAP)(1996). Landfilling: EIS Guideline, New South Wales,Australia.

DOE. Landfill Design Construction and OperationalPractice, Waste Management Paper No 26B (1995),Department of Environment, London, U.K.

Ministry for the Environment (MfE) (November 1992).Landfill Guidelines including Landfill EngineeringGuidelines produced by the Centre for Advanced En-gineering, University of Canterbury, New Zealand.


United States Environmental Protection Agency (1997).Code of Federal Regulations, Title 40, Part 258 SolidWaste Disposal Facility Criteria.

United States Environmental Protection Agency (1993).Solid Waste Disposal Facility Criteria TechnicalManual.

Landfill DesignAugenstein, D, Morck, R, Pacey, J, Reinhart, D andYazdani, R (1999). The Bioreactor Landfill, An Inno-vation in Solid Waste Management, Solid Waste Asso-ciation of North America White Paper.

Daniel, D E (ed.) (1993). Geotechnical Practice forWaste Disposal, Chapman & Hall, London.

Department of Urban Affairs and Planning (DUAP)(1996). Landfilling: EIS Guideline, New South Wales,Australia.

DoE (1994). Licensing of Waste Management Facili-ties, Waste Management Paper No. 4, Department ofEnvironment, London, U.K.

DoE (1995). Landfill Design Construction and Op-erational Practice, Waste Management Paper No 26B,Department of Environment, London, U.K.

Gartung, E (1995). “German practice for landfills,”Proc. 1st Landfill Containment Seminar, Glasgow,Scotland, November 28, pp 8-24.

Gartung, E (1996). “Landfill liners and covers,” Proc.Geosynthetics: Applications, Design and Construc-tion, A. A. Balkema, Maastricht, The Netherlands, pp.55-70.

Giroud and Houlihan (1995). “Design of leachatecollection layers”, Proceedings of the Fifth Interna-tional Landfill Symposium, Volume 2, October 1995,pp. 613-640, Sardinia, Italy.

Koerner, RM (1994). Designing with Geosynthetics,3rd Edition. Prentice Hall Inc. New Jersey, USA.

Koerner, R M and Daniel, DE (1997). Final Covers forSolid Waste Landfills and Abandoned Dumps, ThomasTelford, London, U.K. and ASCE Press, Virginia,U.S.A, pp 4-17.

Ministry for the Environment (MfE). Landfill Guide-lines (November 1992) including Landfill Engineer-ing Guidelines produced by the Centre for AdvancedEngineering, University of Canterbury, New Zealand.

New South Wales Environmental Protection Author-ity (NSWEPA)(1996). Environmental Guidelines:Solid Waste Landfills, Australia.

New South Wales Environmental Protection Author-ity (NSWEPA) (1998). Draft Environmental Guide-lines for Industrial Waste Landfilling, Addendum toEnvironmental Guidelines: Solid Waste Landfills(1996), Australia.

T.A Siedlungssabfall (1991). Second General Admin-istrative Provision to the Waste Avoidance and WasteManagement Act, “Part 1: Technical instructions onthe storage, chemical, physical and biological treat-ment, incineration and disposal of waste requiring


particular supervision of 12.3”, M¸ll-Handbuch, E.Schmidt, Berlin, Vol. 1, 0670, pp. 1-136 (In German).

T. A Siedlungssabfall (1993). Third General Adminis-trative Provision to the Waste Avoidance and WasteManagement Act: Technical Instructions on Recy-cling, Treatment and Storage of Municipal Waste of14.5, M¸ll-Handbuch, E. Schmidt, Berlin, Vol. 1, 0675,pp. 1-152 (In German).

United States Environmental Protection Agency (1996).Landfill Bioreactor Design and Operation, EPA/600/R-95/146, September, 230 pages.

United States Environmental Protection Agency (1997).Municipal Solid Waste Factbook (revised November1997). Title 40, Part 258 of the Code of FederalRegulations.

United States Environmental Protection Agency (Sep-tember 1993). Technical Guidance Document, QualityAssurance and Quality Control for Waste Contain-ment Facilities, EPA/600/R-93/182.

Landfill OperationsNew South Wales Environmental Protection Author-ity (1999). Environmental Guidelines: Assessment andManagement of Liquid and Non-liquid Wastes, Aus-tralia.


Solid Waste Association of North America (SWANA)(1998). Training Sanitary Landfill Operating Person-nel.

United States Environmental Protection Agency (1997).Solid Waste Disposal Facility Criteria. Title 40, Part258 of the Code of Federal Regulations.

United States Environmental Protection Agency (1997).Land Disposal Restrictions. Title 40, Part 258 of theCode of Federal Regulations.

Ministry for the Environment (MfE) (1997). Hazardsof Burning at Landfills.

Ministry for the Environment (MfE) (November 1992).

Landfill Guidelines, including Landfill EngineeringGuidelines produced by the Centre for Advanced En-gineering, University of Canterbury, New Zealand.

Ministry for the Environment (MfE) (1999). WasteAcceptance Criteria at Landfills.

Recommended Further ReadingAlley, WM (ed.) (1993). Regional Ground-WaterQuality, Van Nostrand Reinhold, New York.

Bolton, N (1995). Handbook of Landfill Operations,Blue Ridge Solid Waste Consulting, USA.

Christenson, TH, Cossu, R, Stegmann, R (1992).Landfilling of Waste: Leachate, E&FN Spon, London.

Christenson, TH, Cossu, R, Stegmann, R (1992).Landfilling of Waste: Barriers, E&FN Spon, London.

Christenson, TH, Cossu, R, Stegmann, R (1992).Landfilling of Waste: Biogas, E&FN Spon, London.

DoE (1993). The Potential for Woodland Establish-ment on Landfill Sites, HMSO, London.

McBean, EA, Rovers, FA and Farquhar, GJ (1995).Solid Waste Landfill Engineering and Design, PrenticeHall, USA.

Nielsen, DM (ed.) (1991). Practical Handbook ofGroundwater Monitoring, Lewis Publishers, USA.

Qasim, SR and Chiang, W (1994). Sanitary LandfillLeachate: Generation, Control and Treatment,Technomic, USA.

Reinhart, DR and Townsend, TG (1998). LandfillBioreactor Design and Operation, Lewis Publishers,USA.

Rowe, RK, Quigley, RM and Booker, JR (1995). ClayBarrier Systems for Waste Disposal Facilities, E & FNSpon, London.

Sharma, HD and Lewis, SP (1994). Waste Contain-ment Systems, Waste Stabilization, and Landfills, Wiley,New York.

Tchobanoglous, G, Theisen, H and Vigil, SA (1993.Integrated Solid Waste Management, McGraw Hill,New York.

Appendix 1: Relevant Case Law • 91

Appendix 1Relevant Case Law

1.1. IntroductionSet out below is a summary of the recent case lawrelating to the establishment and operation of landfillsunder the Resource Management Act. It is importantto seek specific legal advice for particular issues.

1.2 Discharge of ContaminantsThe discharge of a contaminant into a stormwater drainthat in turn discharges into water is not a discharge ofa contaminant into water (section 15(1)(a)) but a dis-charge in terms of section 15(1)(b); see Southland RCv Southern Delight Ice Cream Co (1995) 2 ELRNZ, 34.

The definition of discharge in section 2 allows forsomething broader than merely the direct action of aperson. Instead the consequences of a person’s activityare included by the words “emit” or “allow to escape”.Consistent with the policy of preventing contamina-tion in waterways and with Union Steam Ship Co of NZLtd v Northland Harbour Board [1980] 1 NZLR 273(CA), a person can be indirectly liable for a dischargeof contaminant through a failure to act on their behalfor an action of an employee. The causal link betweenthe person charged and the discharge will be a questionof fact in each case.

In AFFCO NZ Ltd v Far North DC (No 2) [1994]NZRMA 224 (PT), the Tribunal accepted that somedischarges to air are so insignificant that they could beignored under the principle of de minimis non curat lex.However, it rejected the proposition that because thedischarges were not discernible beyond the boundariesof the site the principle applied. In particular, unlikedischarges to water, the RMA does not provide formixing zones for discharges to air (section 107(1)).

1.3 Existing Use RightsA private individual cannot rely on section 10(1)(b) toestablish existing use rights. In Wilson v Dunedin CityCouncil (decision no. C50/94), the Tribunal doubtedsection 10(1)(b) was ever intended to provide privatelyowned and operated activities with the benefits ofexisting use rights acquired by virtue of the lawful

establishment of a public work. Designation proce-dures apply only to the activities of Ministers of theCrown, local authorities and duly appointed networkutilities operators.

In assessing an application for the expansion of exist-ing activities, councils may take into account the pastrecord of operators. See Philp v Taranaki RegionalCouncil (decision no. W186/96).

1.4 Application for ResourceConsentSufficient particulars need to be given with an applica-tion to enable those who might wish to make submis-sions on it to be able to assess the effects of theproposed activity on the environment and on their owninterests. See Affco v Far North DC (No. 2), [1994]NZLR 224.

When such an assessment is deficient, the Council andEnvironment Court may have no jurisdiction to hearthe case, see Scott v New Plymouth DC [1993] 2NZPTD 116. See also Affco NZ Ltd v Far NorthDistrict Council [1994] NZRMA 224.

Where several resource consent applications are re-quired for the same project, their assessment shouldtake into account the relevant cumulative effects of thedevelopment as a whole: see Burton v Auckland CC[1994] NZRMA 544.

1.5 Plan ChangeNote that the provision for a private-initiated planchange request to a district plan applies only to anoperative district plan, not to a proposed district plan.See Hall v Rodney DC [1995] NZRMA 537. Becausea request for a plan change cannot be rejected on theground that the district plan is proposed but not yetoperative (Clause 25 of the First Schedule), a proposeddistrict plan cannot be changed until it becomes opera-tive. However, notification of a requested change canproceed.

Appendix 2: Relevant Regulatory and Best Practice Background • 93

Appendix 2Relevant Regulatory and Best

Practice Background

2.1 USA

Legislation and RegulationsNew waste containment facilities (both hazardous andnon-hazardous) are regulated at the federal level underthe Resource Conservation and Recovery Act (RCRA).

Abandoned dumps and other contaminated sites thatrequire corrective action are regulated under the Com-prehensive Environmental Response, Compensation,and Liability Act (CERCLA), commonly known asSuperfund.

Under the RCRA, hazardous and non-hazardous solidwaste landfills are regulated differently. Hazardouswaste landfills are regulated under “subtitle C” andnon-hazardous waste landfills are regulated under “Sub-title D”. Regulated non-hazardous solid waste landfillscan be of two types: industrial waste and municipalsolid waste (MSW). Municipal solid wastes are regu-lated under Subtitle D of the RCRA, hence, MSWlandfills are known as RCRA Subtitle D or USEPASubtitle D landfills.

GeneralIn the USA, regulation is also implemented at the statelevel. In most states, the state regulatory agency has theactual authority for implementing RCRA solid wastelandfill permitting and compliance monitoring. Manystates have their own set of regulations, which cannotbe less stringent than federal regulations. Thus, federalregulations set what is known as “minimum technol-ogy guidance” or MTG.

USA Municipal Solid Waste Landfills(MSWL), i.e. Subtitle D LandfillsRegulations covering all aspects of municipal solidwaste landfills in the United States are found in Title40, Part 258 of the Code of Federal Regulations. Thecitation for the applicable regulation is thus 40CFR258.

Landfill liner for MSWLs (i.e. Subtitle DLandfills)The landfill liner shall consist of a composite liner and

a leachate collection system that is designed and con-structed to maintain less than a 30 cm depth of leachateover the liner.

Composite liner means a system consisting of twocomponents. The upper component must consist of aminimum 30 mil (0.75 mm) flexible membrane liner(FML) and the lower component must consist of atleast a two foot (600 mm) layer of compacted soil witha hydraulic conductivity of no more than 1 x 10-9 m/s.FML components consisting of high densitypolyethylene (HDPE) shall be at least 60 mil (1.5 mm)thick. The FML component must be installed in directand uniform contact with the compacted soil compo-nent.

An alternative liner system may be approved. Thealternative design must ensure that the concentrationvalues of chemicals listed in Table 1 of Section 258.40(Design Criteria) will not be exceeded in the upper-most aquifer at the relevant point of compliance, asspecified by the Director of an approved state.

Landfill Covers for MSWLs (i.e. SubtitleD landfills)The final cover must be designed to minimise infiltra-tion and erosion. The final cover must be designed andconstructed to:

• have a permeability less than or equal to the perme-ability of any bottom liner system or natural subsoilspresent, or a permeability no greater than 1 x 10-7

m/s, whichever is less; and

• minimise infiltration through the closed MSWL byuse of an infiltration layer that contains a minimum450 mm of earthen material; and

• minimise erosion of the final cover by use of anerosion layer that contains a minimum 150 mm ofearthen material that is capable of sustaining nativeplant growth.

An alternative final cover design that includes anequivalent infiltration and erosion layer may be ap-proved.


Post closure care and maintenance is required for atleast 30 years, unless a different period is approved.

2.2 Germany

LegislationIn Germany it is mandatory to handle waste in such away that any contamination of the ground, as well asground and surface water is prevented. Cognisant ofthis, the Federal Government enacted the Waste Act(Abfallgesetz (AbfG)) and the Water Act(Wasserhaushaltsgesetz (WHG)). In addition, specifictechnical instructions have been promulgated underfederal law with the objective being the establishmentof a technical framework to reach the same degree ofsafety in containment, disposal, and management ofwaste materials in all German states.

For the protection of the groundwater, there is the “1st

General Administrative Instruction on the Protectionof Groundwater for Storage and Deposition of Waste”.For hazardous and for municipal waste landfills, thefederal government has issued “Technical Instructionson the Storage, Chemical, Physical and BiologicalTreatment, Incineration and Landfilling of Waste”(TA Abfall 10.04.1990 GMB1.2.170; or TA-A) and“Technical Instructions on Recycling, Treatment andother Management of Municipal Waste” (TASiedlungsabfall, 01.06.1993, Bundesanzeiger or TA-SI).

As in the USA, German states have supplementedthese federal regulations with their own state regula-tions.

Furthermore, there are government-appointed taskgroups and professional groups, which establish tech-nical guidance. For example, during the past 15 years,the geotechnical aspects of solid waste landfills havebeen compiled by a task group of the GermanGeotechnical Society and edited as technical recom-mendations under the German title “Empfehlungendes Arbeitskreises Geotechnik der Deponien undAltalsten” or GDA. The topics covered by the GDArecommendations were adapted to both internationaland European conditions and published as “Geotechnicsof Landfill Design and Remedial Works: TechnicalRecommendations”.

GeneralThe German regulations specify minimum require-ments for the geological features of landfill sites.Special attention is paid to the properties and theplacement of the waste material. The waste body isconsidered a barrier by itself.

Three categories of solid waste landfills are distin-guished with respect to the deposited waste material.The technical requirements of the three landfill catego-ries are documented in the Federal Technical Instruc-tions (TA-A and TA-SI). The chemical composition ofthe constituents of the waste is the governing criterionfor the assignment of the landfill category.

Municipal Solid Waste Landfills (MSWL)i.e. Category II LandfillsThe landfill Category II comprises the majority of solidwaste landfills, since typical municipal solid waste andsimilar materials with respect to their contents ofdangerous substances are assigned to them. Followingthe philosophy that the waste body itself is an impor-tant barrier against the contamination of the environ-ment, very strict criteria have to be met for solid wasteassigned to Category II landfills. The most stringentrequirement is that the content of organic carbon of thewaste material is not allowed to exceed 5% by weight.This means that essentially all domestic waste must betreated in an incinerator, i.e. waste received at Cat-egory II landfills by the year 2005 will be mainlyincinerator ash.

Landfill Liner for MSWLs (Category IILandfills)The liner must be a composite liner of 750 mm ofcompacted clay, placed in three lifts and a geomembraneof 2.5 mm minimum thickness. The hydraulic conduc-tivity of the compacted clay must be less than 5 x 10-10

m/s in all cases. In order to achieve the same quality inall German states, geomembranes used in landfill con-struction must be approved by the Federal Institutionfor Material Research and Testing.

Leachate Collection and RemovalThe lining system includes a drainage blanket abovethe geomembrane liner. The drainage blanket is speci-fied to consist of gravel or coarse rock of no less than16 mm to 32 mm grain diameter.

Landfills must be designed in such a way that theleachate collection and removal system works by gravi-tational flow. Perforated HDPE collection pipes areinstalled at spacings of 30 metres or less. Presentpractice in Germany uses HDPE pipes of at least 200mm internal diameter and wall thickness of about 15 to40 mm, depending on the waste overburden.

Landfill Covers for MSWLs (Category IILandfills)German cover regulations are focussed on surface/protection layers, drainage layers, barrier layers andgas venting/foundation layers. The surface/protection


layer must be adequate for long-term maintenance andreliability. The drainage layer placed above the hy-draulic barrier layer, according to German regulations(TA-A and TA-SI), is a layer of granular soil at least300 mm thick with a minimum hydraulic conductivityof 0.1 cm/s (1 x 10-3 m/s). At many sites, the same 16/32 mm rounded stone required in the leachate collec-tion system is used in the cover system as well.

The German regulations (TA-SI) do not give detailedrequirements for the hydraulic barrier layer of oldCategory II landfill covers. Most barriers are similar toCategory I, i.e. a 500 mm thick compacted clay layerplaced in two 250 mm thick lifts, with a hydraulicconductivity of 5 x 10-9 m/s or less.

The hydraulic barrier system for Category II landfillswill eventually consist of a geomembrane over com-pacted clay. The compacted clay is described above.The geomembrane, by German TA-SI regulations,must be high density polyethylene (HDPE) with aminimum thickness of 2.5 mm. The regulations permitthe use of recycled polymers, however none have beenapproved to date.

A gas venting layer must be provided in current Cat-egory II landfills accepting degradable municipal solidwaste. For future Category II landfills where no gas isgenerated, a gas venting layer will not be necessary.

The soil foundation layer placed directly over thewaste is critical in setting the grade (minimum gradientis 5% and the maximum slope is not steeper than3H:1V) for all the overlying cover layers.

2.3 Australia (New SouthWales)

Legislation and RegulationsThe Waste Minimisation and Management Act (1995)introduced a state-wide scheme for licensing wasteactivities and the Waste Minimisation and Manage-ment Regulation (1996) detailed the state-wide licens-ing and reporting scheme.

In NSW, landfills are subject to environmental protec-tion regulation in two stages: planning and operation.

Regulation at the planning stage is via the Environ-mental Planning and Assessment Act and at opera-tional stage through the new waste licensing schemevia the Waste Minimisation and Management Regula-tion.

The State Environmental Planning Policy (SEPP) es-tablishes the Minister of Urban Affairs and Planning as

the consent authority for regional putrescible landfillproposals from local councils, waste planning andmanagement boards or from the waste service. Localcouncils are still responsible for determining applica-tions for individual local council landfills.

Assessment and classification of waste for landfilldisposal is addressed in the Environmental Guidelines:Assessment, Classification and Management of Non-Liquid Wastes 1997 (Waste Guidelines).

In short, NSW classifies waste in the following order,ranging from the least harmful to the most harmful tothe environment:

• inert waste;

• solid waste;

• industrial waste; and

• hazardous waste.

The 1996 EPA Landfill Guidelines (“EnvironmentalGuidelines: Solid Waste Landfills”) outlined the envi-ronmental performance requirements and providedbenchmark techniques for the operation of solid wastelandfills. The 1998 EPA draft addendum to the LandfillGuidelines (Draft Environmental Guidelines for In-dustrial Waste Landfilling, April 1998) set out theadditional management requirements for industrialwaste landfilling.

Leachate Barrier System (Landfill Liner)for Solid Waste LandfillsCharacteristics of a suitable liner include:

• recompacted clay or modified soil liner at least 900mm thick with an in-situ permeability less than1 x 10-9 m/s;

• liner or barrier surface should be formed so thatonce settling is finished, the upper surface of theliner or barrier must have a longitudinal gradient ofgreater than 1% and transverse gradient of greaterthan 3%; and

• if the landfill is located in an area of poor hydrologi-cal conditions or otherwise poses a significantthreat to groundwater or surface water, the com-pacted clay or modified soil liner should be overlainwith a flexible membrane liner (FML) at least 1.5mm thick and with a minimum permeability of 1 x10-14 m/s.

Leachate Collection System for SolidWaste LandfillsAcceptable designs include the following:


• A drainage layer with permeability greater than 1 x10-3 m/s and at least 300 mm thick should beinstalled over the liner.

• Gravel or a combination of gravel and a geonet maybe used. The gravel should ideally be rounded,smooth surfaced, of grain size greater than 20 mm,relatively uniform in grain size, non-reactive inmildly acidic conditions, and free of carbonates.

• Perforated collector pipes placed within the drain-age layer should not be at intervals of more than 50metres. Pipes should generally be a minimum of150 mm in diameter and have a minimum longitu-dinal gradient of 1%.

Landfill Covers for Solid Waste LandfillsThe landfill final capping should consist of:

• the seal bearing surface — designed and engi-neered layer;

• the gas drainage layer — minimum thickness 300mm;

• the sealing layer — compacted clay (permeabilityless than 1 x 10-8 m/s) of 500 mm minimumthickness;

• the infiltration drainage layer — minimum thick-ness 300 mm, permeability greater than 1 x 10-5 m/s; and

• the revegetation layer — minimum thickness 1000mm.

The final settlement of the seal bearing surface shouldleave a gradient of greater than 5% to defined drainagepoints.

2.4 United Kingdom

Legislation and RegulationsAll landfill sites in the UK are subject to legislativecontrols and landfill development cannot proceed with-out necessary consents.

There are three main areas of legislative control relat-ing to landfill developments:

• the planning system, which controls the develop-ment and use of land in the public interest, andaffects the choice of site location;

• pollution control legislation, incorporating wastemanagement licensing and measures for environ-mental protection; and

• regulations and statutory controls to protect healthand safety and ensure minimum standards for engi-neering construction.

Legislation and guidance on its application are foundin a range of documents including:

• The Environmental Protection Act, 1990;

• The Water Resources Act, 1991;

• The Controlled Waste Regulations, 1992;

• The Waste Management Licensing Regula-tions,1994;

• The Environmental Protection (Duty of Care) Regu-lations, 1991;

• The Special Waste Regulations, 1995;

• The Town and Country Planning Act, 1990;

• The Government and Industry Codes of Practice;and

• The Department of Environment (DoE) circulars,guidance notes and waste management papers.

Planning control is exercised through the local authori-ties, whilst waste management licensing is the respon-sibility of the waste regulatory body, at present theWaste Regulation Authority (WRA). Water pollutioncontrol is a function of the National Rivers Authority(NRA) in England and Wales and the River Purifica-tion Authorities (RPA) in Scotland.

GeneralThe DoE’s Waste Management Paper No 26B pro-vides guidance on the overall development of landfillsites, encompassing landfill design, construction andoperational practice.

WMP26B’s guidance to Waste Regulation Authorities(WRAs) is non-statutory: a WRA is thus not obliged tohave regard to it. In substituting its own view, how-ever, the WRA should ensure that it informs licensees,applicants and intending applicants what its intentionsand requirements are. To do otherwise might be todisregard the statutory guidance in Waste Manage-ment Paper No 4 (WMP4:Licensing of Waste Manage-ment Facilities).

The guidance embodied in WMP26B is based on:

• a holistic approach to landfill design and operation,utilising scientific and engineering skills as anintegrated process from initial conception throughto final capping, restoration and aftercare; and


• use of a site-specific risk assessment, rather than aprescriptive approach to environmental protection,for each element and at each stage in the project, inorder to determine the overall design and opera-tional practices appropriate to the environmentalsettling of each individual landfill site.

Design standards fall into the categories of:

• absolute standards;

• performance standards; and

• guidelines.

Landfill LinersThe selection of a liner system is a complex processwhich should be determined on a site-specific basis.

Liner systems include single-liner, composite-liner,double-liner, or multiple-liner systems

For clay liners, a typical specification is that “thematerial should be placed and compacted in layers toform a homogeneous layer with a total thickness noless than 1000 mm with a hydraulic conductivity of nogreater than 1 x 10-9 m/s

For composite-, double- or multiple-liner systems, thethickness of the clay liner should never be less than 600mm.

Leachate Collection and RemovalThe NRA (1995) Internal Guidance Note No 8Leachate Management suggests the following stand-ards for construction of leachate collection systems:

• base slope 2%;

• drainage blanket 300 mm Type B filter drainagemedia;

• 200 mm diameter perforated smooth bore pipes;and

• possible geotextile or geonet at waste/drainageblanket interface.

Landfill CoverThe five possible components are the:

• surface layer;

• protection layer;

• drainage layer, pipework zone;

• barrier layer; and

• gas collection layer.

Detailed guidance on the design and construction ofthe capping system is given in Waste ManagementPaper No 26E, Landfill Restoration and Post ClosureManagement (1995).

Appendix 3: Landfill Management Plan Outline Table of Contents • 99

Appendix 3Landfill Management Plan Outline

Table of Contents

IntroductionApprovalsDesign ParametersStagingProjected LifeEnd Use

ManagementSite Owner and OperatorManagement StructureLandfill Operations ContractRight of AccessOperating HoursStaff RequirementsTrainingOccupational Safety and HealthOperators GuideAnnual Review and Reporting

Landfill OperationsSite Preparation— Tip head— Signs— Screens— Perimeter FencingWater Control— Stormwater— Leachate

Landfill Gas Control

Waste Acceptance

— Prohibited Wastes— Acceptable Wastes— Waste Acceptance Criteria— Areas for Disposal— Method of Disposal— Documentation and Record Keeping

Tipping

— Access Roads— Method of Tipping— Size of Face

— Height of Lifts

Compaction

— Method of Compaction— Degree of Compaction— Method of Compaction Testing— Frequency of Compaction Testing

Cover Material

— Daily Cover Requirements— Intermediate Cover Requirements— Final Cover Requirements— Importing of Cover Material— Stockpiling of Cover Material— Vegetation

Control of Nuisances

— Spillages— Noise— Odour— Litter— Dust— Vermin— Birds— Scavengers

Monitoring

— Groundwater— Surface Water— Landfill Gas— Refuse Quantities— Complaints— Reporting

Emergency Procedures

— Fire— Landfill— First Aid— Emergency Contacts

ReinstatementFinal LandformClosure and Aftercare

Appendix 4: Waste Classification for Landfill Disposal • 101

Appendix 4Waste Classification for Landfill

Disposal

NOTES: Numbering and terminology used are gener-ally consistent with the ANZECC classification sys-tem and refer in the first instance to untreated wastes.As the system contains both waste types and constitu-ents, more than one category may be applicable to aparticular waste and therefore all categories need to bechecked to determine whether landfill disposal may beappropriate.

A Waste Prohibited from Landfills

1 Characteristics

H1 Explosives

H2 Gases

H3 Flammable liquids

H4.1 Flammable solids

H4.2 Substances or wastes liable tospontaneous combustion

H4.3 Substances or wastes, which in contactwith water emit flammable gases

H5.1 Oxidising substances

H5.2 Organic peroxides

H6.2 Infectious substances

H7 Radioactive materials1

H8 Corrosives

H10 Liberation of toxic gases in contact with airor water

H13 Capable, by any means after disposal, ofyielding another material, e.g. leachate,which possess any of the above character-istics

2 Waste types which may exhibit the abovecharacteristics

Cyanides, surface treatment and heat treatmentwastes

A100 Cyanide containing waste from treatmentof metals

A110 Cyanide containing waste from heat treat-ment and tempering

A120 Complexed cyanides

A130 Other cyanides

Acids

B100 Sulphuric acid

B110 Hydrochloric acid

B120 Nitric acid

B130 Phosphoric acid

B140 Chromic acid

B150 Hydrofluoric acid

B160 Sulphuric/hydrochloric acid mixtures

B170 Other mixed acids

B180 Organic acids

Alkalis

C100 Caustic soda, potash, alkaline cleaners

C110 Ammonium hydroxide

C140 Other (hazardous substances must bespecified)

Inorganic chemicals

D100 Metal carbonyls

D120 Mercury

D280 Alkali metals

D330 Sulphur

Reactive chemicals

E100 Oxidising agents

E110 Reducing agents

E120 Explosives

E130 Highly reactive chemicals


Paints, lacquers, varnishes, inks, dyes, pigments,adhesives

F200 Uncured adhesives or resins

Organic solvents

G100 Ethers

G110 Non-halogenated (FP>61oC), n.o.s.

G120 Non-halogenated (FP<61oC), n.o.s.

G130 Halogenated (FP>61oC), n.o.s.

G140 Halogenated (FP<61oC), n.o.s.

G150 Halogenated n.o.s.

G160 Wastes from the production and formula-tion of organic solvents

G180 Others (hazardous substances must bespecified)

Pesticides

H100 Inorganic, organometallic pesticides

H110 Organophosphorus pesticides

H120 Nitrogen-containing pesticides

H130 Halogen-containing pesticides

H140 Sulphur-containing pesticides

H150 Mixed pesticide residues

H160 Copper-chrome-arsenic (CCA)

H170 Other inorganic wood preserving com-pounds

H180 Organic wood preserving compounds

Oils, hydrocarbons, emulsions

J100 Waste mineral oils unfit for their originalintended use (lubricating, hydraulic)

J110 Waste hydrocarbons

J120 Waste oils/water, hydrocarbon/water mix-tures, emulsions (mainly oil and or hydro-carbons, i.e. >50%)

J130 Waste oils/water, hydrocarbon/water mix-tures, emulsions (mainly water, i.e. >50%)

J140 Transformer fluids (excluding PCBs)

J150 Other (cutting, soluble oils)

J160 Tars and tarry residues (including tarry

residues arising from refining and anypyrolytic treatment)

Putrescible, organic wastes

K100 Liquid animal effluent (poultry and fishprocessing)

K150 Liquid vegetable oils and derivatives

K170 Liquid animal oils and derivatives

K180 Abattoir effluent

K200 Food processing effluent

Industrial washwaters, effluents

L100 Truck, machinery washwaters with or with-out detergents

L101 Car wash waters with or without deter-gents

L120 Cooling tower washwater

L130 Fire wastewaters

L140 Textile effluent

L150 Other industrial plant washdown water

Organic chemicals

M100 Polychlorinated biphenyls (PCBs)and/or polyterphenyl (PCTs) and/orpolybrominated biphenyls (PBBs)

M110 Equipment containing PCBs and/or PCTsand/or PBBs

M120 Solvents and materials contaminated withPCBs and/or PCTs and/or PBBs

M150 Phenols, phenol derivatives includingchlorophenols

M160 Halogenated compounds n.o.s.

M170 Any congener of poly-chlorinated dibenzo-furan

M180 Any congener of poly-chlorinated dibenzo-p-dioxin

M210 Organic cyanides

M250 Liquid surfactants and detergents

Clinical and pharmaceutical wastes

R100 Infectious substances

R110 Pathogenic substances

Appendix 4: Waste Classification for Landfill Disposal • 103

R130 Cytotoxic substances

Miscellaneous

T100 Waste chemical substances arising fromresearch and development or teaching ac-tivities, which are not identified

B Wastes possibly suitable formunicipal landfill disposal— solids and sludges

1 Characteristics

H6.1 Poisonous substances

H11 Toxic substances (chronic or delayed ef-fects)

H12 Eco-toxic

2 Waste types which may exhibit the abovecharacteristics

Alkalis

C120 Waste lime and cement

C130 Lime/caustic neutralised wastes contain-ing metallic constituents

Inorganic chemicals

D110 Inorganic fluoride compounds

D120 Mercury compounds

D121 Equipment and articles containing mer-cury

D130 Arsenic, arsenic compounds

D140 Chromium, chromium compounds

D141 Tannery wastes containing chromium

D150 Cadmium, cadmium compounds

D160 Beryllium, beryllium compounds

D170 Antimony, antimony compounds

D180 Thallium, thallium compounds

D190 Copper compounds

D200 Cobalt, cobalt compounds

D210 Nickel, nickel compounds

D220 Lead, lead compounds

D230 Zinc compounds

D240 Selenium, selenium compounds

D250 Tellurium, tellurium compounds

D260 Silver compounds

D261 Photographic waste containing silver

D270 Vanadium, vanadium compounds

D280 Alkali metal containing compounds

D290 Barium, barium compounds

D310 Boron, boron compounds

D320 Inorganic non-metallic phosphorus com-pounds

D330 Inorganic sulphur containing compounds

D340 Other inorganic compounds and complexes

Putrescible, organic wastes

K100 Animal residues (poultry and fish process-ing wastes)

K101 Scallop processing residues

K120 Grease interceptor trap waste – domestic

K130 Bacterial sludge (septic tank)

K132 Sewage sludge and residues

K140 Tannery wastes not containing chromium

K150 Vegetable oil derivatives

K160 Vegetable wastes

K170 Animal oil derivatives (e.g. tallow)

K180 Abattoir residues

K190 Wool scouring wastes

Organic chemicals

M130 Non-halogenated (non-solvent) n.o.s.

M140 Heterocyclic organic compounds

M190 Organic phosphorus compounds

M200 Organic sulphur compounds

M220 Organic isocyanates

M230 Amines and other nitrogen compounds(aliphatic)

M240 Amines and other nitrogen compounds(aromatic)


M250 Surfactants and detergents

M260 Highly odorous (eg. mercaptans, acrylate)

M270 Methacrylate compounds

M280 Other (hazardous substances must be speci-fied)

Solid/sludge requiring special handling

N100 Drums which have contained hazardoussubstances (and which have been triple-rinsed)

N110 Containers and bags which have containedhazardous substances (hazardous sub-stances must be specified)

N120 Contaminated soils (hazardous substancesmust be specified)

N130 Spent catalysts (contaminants must bespecified)

N140 Fire debris

N150 Fly ash

N160 Encapsulated wastes

N170 Chemically fixed wastes

N180 Solidified or polymerised wastes

N190 Ion-exchange column residues

N200 Industrial waste treatment sludges andresidues n.o.s.

N210 Residues from pollution control operations

N220 Asbestos2

N230 Synthetic mineral fibres

Clinical and pharmaceutical wastes3

R120 Pharmaceuticals and residues

R140 Wastes from the production and prepara-tion of pharmaceutical products

Miscellaneous

T120 Scrubber sludge

T130 Photographic chemicals which do not con-tain silver

T140 Inert sludges/slurries (eg. clay, ceramicsuspensions)

T150 Used tyres/tyre wastes

T190 Other (hazardous substances must be speci-fied)

1 Some radioactive wastes may be able to be landfilled-refer Guidelines for Disposal of Radioactive Substances– National Radiation Laboratory

2 Refer to Asbestos Regulations 1983

3 Some clinical wastes such as non-sharp, non-infectiousand non-pathological wastes may be able to be landfilled—Department of Health

Appendix 5: USEPA Toxicity Characteristic Leaching Procedure Limits • 105

Appendix 5USEPA Toxicity Characteristic Leaching

Procedure LimitsIn the case of a Category A or B waste (as detailed inAppendix D) that has received treatment, if the follow-ing limits are exceeded by a leachate extract of the

waste with respect to any of the listed constituents, thenthe material is not suitable for unrestricted landfilldisposal.

Contaminant Examples Maximum Concentration(mg per litre)

Arsenic 5.0Barium 100.0Benzene 0.5Cadmium 1.0Carbon Tetrachloride 0.5Chlordane 0.03Chlorobenzene 100.0Chloroform 6.0Chromium 5.0Endrin 0.02m-Cresol 200.0*o-Cresol 200.0*p-Cresol 200.0*1,4-Dichlorobenzene 7.51,2-Dichloroethane 0.51,1-Dichloroethylene 0.72,4-Dinitrotoluene 0.132,4-Dichlorophenoxyacetic acid 10.0Heptachlor 0.008Hexachloro – 1,3-butadiene 0.5Hexachlorobenzene 0.13Hexachloroethane 3.0Lead 5.0Lindane 0.4Mercury 0.2Methoxychlor 10.0Methyl ethyl ketone 200.0Nitrobenzene 2.0Pentachlorophenol 100.0Pyridine 5.0Selenium 1.0Silver 5.0Tetrachloroethylene 0.7Toxaphene 0.5Trichloroethylene 0.72,4,5-Trichlorophenol 400.02,4,5-Trichlorophenoxypropionic acid 1.02,4,6-Trichlorophenol 2.0Vinyl chloride 0.2Sulphides 50 ppmCyanides 50 ppmAsbestos Any amount if unbound in matrix

(so as to prevent fibres beingairborne)

Total Halogenated CompoundsTotal Synthetic Non-halogenated CompoundsPolychlorinated Biphenyls

1,000 ppm10,000 ppm 50 ppm

* Total of all cresols not to exceed 200

Appendix 6: NSWEPA Values for Solid Waste Landfills • 107

Appendix 6NSWEPA Leachable Concentration and

Total Concentration Values for SolidWaste Landfills

Contaminant threshold (CT) is the maximum allow-able concentration if a TCLP test is not carried out.Leachable concentration limits and total concentration

limits are used together in accordance with NSWEPA(1999) Environmental Guidelines: Assessment andManagement of Liquid and Non-liquid Wastes.

Contaminant ContaminantThreshold

(mg per litre)

LeachableConcentration(mg per litre)

TotalConcentration(mg per litre)

Arsenic 100 5.0 500Benzene 10 0.5 18Benzo(a)pyrene 0.8 0.04 10Beryllium 20 1.0 100Cadmium 20 1.0 100Carbon Tetrachloride 10 0.5 18Chlorobenzene 2000 100 3600Chloroform 120 6 216Chromium (VI) 100 5 1900m-Cresol 4000 200 7200o-Cresol 4000 200 7200p-Cresol 4000 200 7200Cresol (total) 4000 200 7200Cyanide (amenable) 70 3.5 300Cyanide (total) 320 16 59002,4-D 200 10 3601,2-Dichlorobenzene 86 4.3 1551,4-Dichlorobenzene 150 7.5 2701,2-Dichloroethane 10 0.5 181,1-Dichloroethylene 14 0.7 25Dichloromethane 172 8.6 3102,4-Dinitrotoluene 2.6 0.13 4.68Ethylbenzene 600 30 1080Fluoride 3000 150 10000Lead 100 5 1500Mercury 4 0.2 50Methyl ethyl ketone 4000 200 7200Molybdenum 100 5 1000Nickel 40 2 1050Nitrobenzene 40 2 72C6-C9 petroleum hydrocarbons N/A N/A 650C10-C36 petroleumhydrocarbons

N/A N/A 10000

Phenol (non-halogenated) 288 14.4 518Polychlorinated biphenyls N/A N/A <50Polycyclic aromatichydrocarbons (total)

N/A N/A 200


Contaminant ContaminantThreshold

(mg per litre)

LeachableConcentration(mg per litre)

TotalConcentration(mg per litre)

Scheduled chemicals * N/A N/A <50Selenium 20 1 50Silver 100 5.0 180Styrene (vinyl benzene) 60 3 1081,1,1,2 - Tetrachloroethane 200 10 3601,1,2,2 - Tetrachloroethane 26 1.3 46.8Tetrachloroehylene 14 0.7 25.2Toluene 288 14.4 5181,1,1 – Trichloroethane 600 30 10801,1,2 – Trichloroethane 24 1.2 43.2Trichloroethylene 10 0.5 182,4,5-Trichlorophenol 8000 400 144002,4,6-Trichlorophenol 40 2 72Vinyl chloride 4 0.2 7.2Xylenes 1000 50 1800

*Scheduled Chemicals

AldrinBenzene, hexachloroBenzene, pentachloronitroAlpha-BHCBeta-BHCGamma-BHC LindaneDelta-BHCChlordaneDDDDDEDDTDieldrinEndrinEndrin aldehydeHeptachlorHeptachlor epoxideHexachloropheneIsodrinPentachlorobenzenePentachlorophenol1,2,4,5-tetrachlorobenzene2,3,4,6- trichlorobenzene2,4,5-trichlorophenoxyacetic acid, saltsand esters

Index • 109

Index

Aacceptable wastes 53access and traffic 19, 25-26, 52aerobic landfill 24after-care 63alternative daily cover 56analysis and review of monitoring data 77 - 78

statistical methods 78trigger levels 78trigger level system 79

Assessment of Effects on the Environment (AEE) 11

Bbiological quality, water 74bioreactor landfill 23birds 58

Ccells 28-30Clean Air Act(1972) 7closure 63community issues 20-21compaction 56construction, QA/QC 46consultation 16cover systems

advantages and disadvantages 45alternate daily cover 56daily cover 43, 56final cover 44, 57intermediate cover 44, 57

Ddaily cover 56density, compacted refuse 28density, target 28design considerations

access 25, 52cells 28charging booth 26final use 27investigations and site characterisation 25landfill siting 25landscaping 27objectives 24transfer station 25weighbridge 26

designations 9desk-top study 14discharge permits

to air 7to land 6to water 6

district plans 9-11dust 57

Eeconomic assessment 15

engineered liner systems 13Environment Court 12Environmental Risk Management Authority (ERMA) 4equipment selection 55existing use rights 8

Ffinal cover 44, 57fire prevention 59

deep-seated fires 60flares 82Hazards of Burning at Landfills 60management provisions 60surface fires 60

flares 82flies 59flood plains 18

Ggeology 17geosynthetic materials 46groundwater drainage 30groundwater management 30groundwater monitoring 66 - 73

design requirements 69detection limits 72frequency and timing 70monitoring parameters 69monitoring points 68sampling requirements 70

Hhazardous waste storage compartment 27Health and Safety in Employment Act 7, 52health and safety plan 52hydrogeology 18

Iintermediate cover 44, 57

KKarst geology 17Karst terrain 18

Lland use consents 8landfill cover systems 43landfill design trends

international 24New Zealand 24

Landfill Engineering Guidelines (1992) 1landfill gas 40-43, 62-63

control 62generation 62monitoring 62

landfill gas management 20, 40-42advection 41


gas control 41gaseous diffusion 41gas disposal 42gas production 40monitoring 41-42, 62potential problems 40

landfill gas migration 41 - 42passive venting 42physical barriers 42suction driven extraction 42

landfill gas monitoring 79 - 82spiking surveys 80

landfill management plan 51landfill site capacity 28landfill siting criteria 17landfill types 3

cleanfill 3hazardous waste 3industrial waste 3municipal solid waste 3

landscaping 27leachate

control 61factors affecting generation 32field capacity 35generation 60Hydrological Evaluation of Landfill Performance(HELP) 35monitoring 61, 65production rates 34recirculation 38water balance equation 34

leachate characteristics 31anaerobic phase 31facultative organisms 31main components 31New Zealand landfills 32

leachate collection and removal systems 35 - 38leachate management 20leachate recirculation 23leachate retention system 35 - 38leachate treatment and disposal 39 - 40

land treatment and disposal 40on-site treatment technologies 40spray irrigation 40subsurface irrigation 40

liner constuctionbentonite additive 37 - 38liner designs 36permeability specifications 37

litter 57

MManagement of Hazardous Waste 3management plan 51monitoring locations, leachate 66monitoring of landfills 65

Nnoise 59notification

non-notified application 12notified application 11

nuisance control 57

Oodour 58

Pphysico-chemical water quality 74prohibited wastes 53putrescible waste 31

Qquality assurance/quality control 46

Rrandom load inspections 54record keeping 55Regional Councils, functions 5retention and liner systems, leachate 35Resource consents

application process 11coastal permits 8discharge permits 6discharge to air 6discharge to land 6discharge to water 6subdivision consents 8

Resource Management Act (1991) 1, 5administrative enforcement 10civil enforcement 10enforcement orders 10offence provisions 10

roading 55

Ssampling protocols

analysis 72collection 72methods and equipment 72QA/QC requirements 72storage and transport 72

sediment quality 74site access criteria 52site capacity 28site investigations 14-15site selection 13-17

consultation 14, 16desk-top study 14economic assessment 14, 15site investigations 14

site stability 18siting criteria 17, 25staffing 51strategic waste management issues 13stormwater control 61subsurface gas monitoring 80surface gas monitoring 80

ambient air sampling 81flame ionisation detection 81flux box testing 81instantaneous surface monitoring 81integrated surface sampling 81visual inspection 80

surface hydrology 18surface water and stormwater management 30, 61surface water monitoring

detection limits 77

Index • 111

locations for monitoring 74monitoring programme 73parameters for quality monitoring 74sampling and analytical protocols 76Whole Effluent Toxicity (WET) test 74

synthetic drainage material (Geonet) 38

TTerritorial Authorities

designations 9district plans 9functions 6

topography 19Town and Country Planning Act 8Toxicity Characteristic Leaching Procedure (TCLP) 53training 51trigger levels 78-79

Vvermin 59visual impacts 55

WWaste Analysis Protocol 55waste acceptance criteria (WAC) 52waste classification 2

cleanfill material 2hazardous waste 3industrial waste 3municipal solid waste 3

waste compaction 55waste disposal application 53Water and Soil Conservation Act (1967) 8water permits 7whole effluent toxicity testing 74wheel wash facilities 27

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