Stage 1 and 2 Environmental Investigations NT/K · 6 csr section - nt0054, ust canteen 7 csr...

Environmental Resources Management Australia

Level 1, 60 Leichhardt St, Spring Hill QLD 4004

Telephone +61 7 3839 8393Facsimile +61 7 3839 8381

www.erm.com

FINAL REPORT

Department of Defence

Stage 1 and 2 EnvironmentalInvestigations NT/KRAAF Base Tindal

June 2007

FOI 463/17/18 Item 6 Serial # 1

Page 317 of 4750

FINAL REPORT

Department of Defence

Stage 1 and 2 EnvironmentalInvestigationsRAAF Base Tindal

June 2007

Reference: 0042239 RP1 Stage 1 & 2 Tindal

This report has been prepared in accordance with thescope of services described in the contract or agreementbetween Environmental Resources ManagementAustralia Pty Ltd ACN 002 773 248 (ERM) and theClient. The report relies upon data, surveys,measurements and results taken at or under theparticular times and conditions specified herein. Anyfindings, conclusions or recommendations only apply to the aforementioned circumstances and no greaterreliance should be assumed or drawn by the Client.Furthermore, the report has been prepared solely for use by the Client and ERM accepts no responsibility for itsuse by other parties

For and on behalf of Environmental Resources ManagementAustralia

Approved by:

Signed:

Position:

Date June 2007


s47G

s47G

Page 318 of 4750

CONTENTS

EXECUTIVE SUMMARY

GLOSSARY

1 INTRODUCTION

1.1 TERMS OF REFERENCE 1.11.2 APPROACH AND TARGET LIST OF SITES 1.11.2.1 APPROACH UNDER NEPM (SITE CONTAMINATION) 1.11.2.2 DEFENCE APPROACH TO SITE CONTAMINATION AND CSR 1.21.2.3 CSR SITES AT RAAF TINDAL 1.31.3 TARGET SITES INVESTIGATED UNDER THIS COMMISSION 1.51.4 PROJECT GOALS AND OBJECTIVES 1.81.5 STRUCTURE OF THIS REPORT 1.9

2 STAGE 1 AND 2 GENERAL SCOPE AND METHODOLOGY

2.1 GENERAL PROCEDURE 2.12.2 STAGE 1 SCOPE OF WORKS AND METHODOLOGY 2.12.2.1 REPORTS AND DATA REVIEWED 2.12.2.2 DESKTOP SITE HISTORY REVIEW AND SITE RECONNAISSANCE 2.22.2.3 IDENTIFIED AREAS AND CHEMICALS OF CONCERN 2.32.2.4 CONCEPTUAL SITE MODEL 2.32.2.5 STAGE 1 RISK ASSESSMENT 2.42.2.6 SAMPLING AND ANALYSIS PLAN 2.42.3 STAGE 2 GENERAL SCOPE OF WORKS AND METHODOLOGY 2.52.4 SELECTION OF ASSESSMENT CRITERIA 2.62.5 DEFENCE RISK ASSESSMENT PROTOCOL 2.82.6 PROJECT TEAM 2.1

3 RAAF BASE TINDAL – GENERAL SITE DESCRIPTION

3.1 BASE LAYOUT AND FUNCTIONS 3.13.1.1 CURRENT AND PROPOSED FACILITY ACTIVITIES 3.23.1.2 FUTURE/ PROPOSED LAND USES 3.33.2 GEOLOGY AND SOILS 3.33.3 HYDROGEOLOGY 3.43.3.1 GROUNDWATER USAGE AND RECORDS 3.43.3.2 SURFACE WATER AND DRAINAGE 3.73.4 SURROUNDING LAND USE 3.8

4 CATCHMENT WIDE GROUNDWATER MONITORING

4.1 SUMMARY OF GROUNDWATER CHARACTERISTICS 4.2

5 CSR SECTION – NT0072, MEOMS


19 of 4750

CONTENTS

6 CSR SECTION - NT0054, UST CANTEEN

7 CSR SECTION – NT0064, FIRE TRAINING GROUND

8 CSR SECTION – NT0076, FUEL FARM 1

9 CSR SECTION – NT0077, FUEL FARM 2

10 RECOMMENDATIONS AND SUMMARY OF OUTCOMES

10.1 CONCEPTUAL SITE MODEL 10.110.1.1 SOURCES 10.110.1.2 RECEPTORS 10.110.1.3 PATHWAYS 10.210.1.4 SUMMARY 10.210.2 COMPARISON OF STAGE 1 AND STAGE 2 RISK ASSESSMENT RESULTS. 10.210.3 SUMMARY OF OUTCOMES 10.410.4 MONITORING PROGRAMME 10.810.4.1 GROUNDWATER MONITORING 10.810.4.2 SURFACE WATER AND SEDIMENT MONITORING 10.11

11 LIMITIATIONS EXCEPTION OF ASSESSMENT

12 REFERENCES

ANNEX A STANDARD OPERATING PROCEDUREANNEX B CONTAMINATION RISK ASSESSMENT GUIDANCEANNEX C PREVIOUS GROUNDWATER MONITORNG GAUGING AND ANALYTICAL DATAANEEX D LABORATORY CERTIFICATESANNEX E QA/QC VALIDATIN SECTION


Page 320 of 4750

ENVIRONMENTAL RESOURCES MANAGEMENT AUSTRALIA 0042239 RAAF BASE TINDAL V1/ FINAL REPORT/JUNE 2007

i

EXECUTIVE SUMMARY

Environmental Resources Management were appointed by the Department of Defence(DoD), Corporate Services and Infrastructure Group (Defence) to undertake a Stage1 & 2 Environmental Investigation at RAAF Base Tindal located approximately13km to the south east of the township of Katherine in the Northern Territory.

The project represents an element of the Defence risk management strategy requiring the investigation and assessment of target sites which have been identified as havingthe potential to have caused contamination of soil and groundwater. The works arealso required to identify improvements that can be made to site activities to minimise the potential for future impacts.

The programme of environmental investigation undertaken at Defence facilitiesacross the country, of which this package of works comprises just one component, has been implemented by the Department of Defence National Contamination Unit inCanberra to ensure a risk based approach is applied to the investigation andassessment process in order to deliver consistent outcomes.

Nine sites located within RAAF Tindal were identified for investigation under thiscommission. The sites are listed on a Defence Contaminated Site Register (CSR)which is a database consisting of decontaminated or potentially contaminated sitesmaintained by the Department of Defence. The sites were selected for Stage 1 andStage 2 Environmental Investigation based on the perceived level of risk to theenvironment or human health. The target sites are set out below.

Target List of Sites for Stage 1 and Stage 2 Investigation

CSR Reference Title Issue

NT0064 Fire training Ground Hydrocarbons and chemicals of oncern associated with AFFF in soil and groundwater

NT0054 UST Canteen Potential for hydrocarbon impact in soil and groundwater associated with bulk fuel handling and storage in USTs.

NT0076 Fuel farm 1 Potential for hydrocarbon impact in soil andgroundwater associated with bulk fuel handlingand storage in ASTs.

NT0077 Fuel farm 2 Potential for hydrocarbon impact in soil andgroundwater associated with bulk fuel handlingand storage in ASTs.

NT0072 MEOMs Area (inclusive of the following 5 maintenance areas)

NT0053 UST Motor Transport Operation Facility

Known previous hydrocarbon impact in soil and groundwater associated with bulk fuel handling and storage in USTs.

NT0066 Ground Support Equipment maintenance workshops

Potential for hydrocarbon impact to surface water through site discharges to stormwater drainage.


Page 321 of 4750

ENVIRONMENTAL RESOURCES MANAGEMENT AUSTRALIA 0042239 RAAF BASE TINDAL V1/ FINAL REPORT/JUNE 2007

ii

CSR Reference Title Issue

NT0070 Battery Charging Building Potential for impacts to soil and groundwater from battery maintenance including an underground acid neutralisation pit.

NT0259 Special Purpose Vehicles Potential for hydrocarbon impact in soil and groundwater associated with waste oil handling and storage in USTs.

NT0260 Tanker Maintenance Facility Potential for impact to soil and groundwater by hydrocarbons associated with maintenance of tanker fleet.

The Stage 1 Investigations of the sites were undertaken in February 2006 andcomprised site reconnaissance and interviews with key stakeholders. Sampling andAnalytical Plans for Stage 2 Investigations were developed and agreed with Defenceon completion of the Stage 1 Investigations.

The Stage 2 site investigation works were undertaken between March and June 2006.The scope of works included the drilling soils bores and installation of monitoringwells at selected locations within the target sites. Soil samples, groundwater samplesand surface water samples were collected and submitted for analysis for a range ofchemicals of potential concern.

The results of the analysis of samples taken from each site have been compared against available assessment criteria to identify and characterise any sources ofcontamination present.

In general the Stage 2 Investigations have not encountered significant or extensivesources of contamination at the target CSR sites in RAAF Tindal although thefollowing impacts were observed:

Hydrocarbons (diesel range) in soil and as dissolved phase in groundwater in the vicinity of the Motor Transport Unit (NT0053);

PFOS (associated with AFFF use) in soil and groundwater at the FireTraining Area (NT0064);

Hydrocarbon in sediments in drainage channels at Fuel farm 1 (NT0076 and Ground Support Equipment (NT0066)

A refined Conceptual Site Model (CSM) was developed for each site based on thefindings of the investigation and assessment of the laboratory data. The CSM wasused to provide a context to undertake a Stage 2 Risk Assessment using the DefenceContamination Risk Assessment Tool.

Based on the findings of the investigation and consideration of the results of the riskassessment, a review of alternate management strategies was undertaken for each site.The recommended strategy and associated estimated costs at each site are summarised in the following table.


Page 322 of 4750

ENVIRONMENTAL RESOURCES MANAGEMENT AUSTRALIA 0042239 RAAF BASE TINDAL V1 /FINAL REPORT/JUNE 2007

iii

Summary of Proposed Management Strategies

Target Site Stage 2 Risk Band / Priority

Recommended Management Strategy Residual Risk Priority

NT0054: Canteen UST. L/205

Routine (initially biannual) groundwater monitoring to review groundwater quality anprovide an indication of any future impacts with a focus on the down gradient wells.

Routine (annual) tank integrity testing should be completed and establish reporting regimfor tank reconciliations.

Consideration should also be given to the installation of an interceptor on the discharge of surface run-off to the stormwater drainage system

L/210

NT0064 Fire Training Area. H/133

Development of site specific risk based screening criteria.

Undertake a Remediation Pilot Study for ex-situ treatment of PFOS impacted soils.

Groundwater Monitoring including installation of additional wells.

Additional General Management Measures should also be considered:

Secondary Containment for Fuel Bowser and upgrade/ maintenance of bowser.

Discharge from the Settlement Lagoons. Provision of interceptor on the discharge tremove any free or emulsified product present in the effluent.

Provision of permanent fence to control access to Fire Training Area

High – The recommended strategy will not mitigate the current source but establish level of

environmental risk and establish potential

treatment options.

NT0076: Fuel Farm 1. L/193

Provision should also be made clear hydrocarbon impacted sediment from the stormwatedrainage around the site where high concentrations of hydrocarbons may be accumulating isediments (076SS02) and providing an ongoing source of hydrocarbons which may breleased to surface water receptors (Tindal Creek). Thereafter, provision should be made foannual inspections of the drain to establish if further cleaning is required. As part of thimanagement provision, it is recommended that Defence ensure that their Duty of Care

L/210


S47G

Page 323 of 4750

ENVIRONMENTAL RESOURCES MANAGEMENT AUSTRALIA 0042239 RAAF BASE TINDAL V1 /FINAL REPORT/JUNE 2007

iv

Target Site Stage 2 Risk Band / Priority

Recommended Management Strategy Residual Risk Priority

obligations in respect of waste handling are being realised and that waste soils are beingdisposed to an appropriately licensed landfill under the necessary waste transferdocumentation.

Routine (annual) groundwater monitoring to review groundwater quality and provide anindication of any future impacts with a focus on the down gradient wells.

NT0077: Fuel Farm 2. L/210Routine (annual) groundwater monitoring to review groundwater quality and provide anindication of any future impacts with a focus on the down gradient wells. L/210

NT0053 Meoms: UST at Motor Transport M/195

The following recommendations should be considered:Undertake routine passive recovery of product from 053MWA and 053MWB.

Provide additional down gradient monitoring well to augment the monitoring network forfuture assessment of water quality and natural attenuation. In particular a well isrequired to the west south west of the Motor Transport facility;

Undertake routine groundwater monitoring (initially biannual) of selected wells at thesite (NT053). Include monitoring of the Golf Course Bore (Bore No. 2); and

Undertake annual tank integrity testing and establish reporting regime for tankreconciliations.

L/210

NT0066 Meoms: Ground Support Equipment. M/191

Installation of an interceptor to prevent direct discharge of heavily impacted effluent tostormwater drainage. Assume three stage concrete chamber interceptor installed on thestormwater discharge at the site boundary. Costs include for the excavation and removal ofexisting impacted sediments but exclude disposal costs.

L/210

NT0070 Meoms: Battery Charge. L/210 Establish management protocols to monitor the use and maintenance of Acid Neutralisation

Pits. L/210

NT0259 Meoms: Underground Waste Oil

Tank.L/210 Establish management protocols for routine tank inspection and integrity testing. L/210

NT0260 Meoms Tanker Maintenance Unit. L/210 Establish management protocols for managing waste oils in the maintenance facility. L/210

FOI 463/17/18 Item 6 Serial # 1S47G

Page 324 of 4750

ENVIRONMENTAL RESOURCES MANAGEMENT AUSTRALIA 0042239 RAAF BASE TINDAL V1/FINAL REPORT/JUNE 2007

v

In addition to the recommended management strategies for each of the sites targeted under thiscommission, the Stage 2 Investigation works have provided a network of wells to allow futureenvironmental monitoring of groundwater quality. A comprehensive monitoring regime can now beestablished through sampling of selected wells with some supplementary wells (including someexisting registered bores at the site and the installation of up to six additional wells in targetedlocations around the catchment). This can be augmented by undertaking targeted monitoring ofsurface water and sediment conditions in surface water drainage channels and Tindal Creek. Regular monitoring is recommended and would provide a comprehensive time variant assessment ofgroundwater quality and a measure of environmental impacts across the base. Details are provided for establishing a monitoring regime in this report.


S47G

Page 325 of 4750


1.1

1 INTRODUCTION

1.1 TERMS OF REFERENCE

ERM was appointed by Department of Defence, Corporate Services andInfrastructure Group (Defence) to undertake a Stage 2 EnvironmentalInvestigation at RAAF Base Tindal (Tender No. AZ3170) locatedapproximately 320km south east of and around 13km south east of thetownship of Katherine in the Northern Territory as shown NT.TIN.001,located in the Attachment at the end of Section 4.0.

The appointment is based on ERM, the tender submission dated the 26th ofOctober 2005, and the subsequent tender clarification latter dated the 24th ofNovember, 2005. The Terms of Engagement are set out in ERM’s PanelAgreement with Defence. The letter of confirmation from Defence was datedthe 8th December 2005. The works were authorised under Defence PurchaseOrders 4500498554 and 4500494035.

The Stage 1 & 2 Environmental Contamination Investigation has beenundertaken in general accordance with either the National EnvironmentProtection (Assessment of Site Contamination) Measure 1999 or NEPMGuidelines, and as such comprises a combined Desk Study Review (Stage 1)of relevant information followed by site-specific intrusive investigation works (Stage 2) where significant risks were identified on the completion of Stage 1. The scope of Stage 2 was agreed during the project in conjunction withDefence and the Technical Advisor (TA) appointed to this project by Defence: Bengt von Schwerin of Earthtech.

At each Stage in the project, the assessment of risk has been undertaken using the “Contamination Risk Assessment Guidance” published by Defence(Version 1, dated 28 June 2005), which is a tool for quantifying the “true” risk to Defence.

A Stage 1 Contamination Assessment of selected sites at RAAF Tindal wascompleted by ERM in 2005. The findings of this earlier Stage 1 Reportprovided the basis for the scope of the current report.

1.2 APPROACH AND TARGET LIST OF SITES

1.2.1 Approach under NEPM (Site Contamination)

The National Environmental Protection (Site Contamination) Measure, 1999(NEPM) was developed by the National Environmental Protection Council inassociation with the National Health and Medical Research Council primarilyto enable a nationally consistent approach to the assessment of site


Page 326 of 4750


1.2

contamination and to help achieve adequate protection of human health andthe environment.

The NEPM comprises two schedules (Schedule A and B) designed to identifythe recommended process and guidelines for the assessment of sitecontamination. Schedule A of the NEPM provides recommendations for thegeneral process of assessment of site contamination including the threegeneral tiers of assessment:

Preliminary Investigations;

Detailed investigations; and

Risk assessment.

The NEPM Schedule B provides guidelines for data collection, sample designand reporting and supporting documents for the preliminary assessment ofhuman and ecological risks.

The NEPM (Site Contamination) is currently under review. The approach and site Environmental Investigation processes outlined (including the guidelines) are not expected to change significantly.

1.2.2 Defence Approach to Site Contamination and CSR

The potential for significant environmental impact to arise as a result ofactivities previously or currently undertaken on Defence sites represent apotential risk to the environment and Defence operations. These risks havetypically been identified within Environmental Management Plansdeveloped for Defence sites. In response, programs of assessment andmonitoring have been progressively rolled out across selected sites toproactively manage these risks and allow early intervention where significant issues are identified or confirmed.

Defence are currently undertaking works to actively manage risks associated with environmental contamination on Defence land in Australia.

Contaminated Sites Register (CSR)

A strategic, qualitative risk-based approach to the management ofcontaminated Defence land has been adopted by the Directorate ofEnvironmental Impact Management (DEIM). This has resulted in the listingof a Defence Contaminated Sites Register (CSR). A number of medium andhigh-risk sites have been identified at RAAF Base Tindal for assessmentunder this appointment.

The contamination status assigned to the sites at RAAF base Tindal has been based on previous desk top studies and/ or information from a range ofsources including:


Page 327 of 4750


1.3

The EMP for the base;

Information provided by regional Environmental Officers (REOs); and

Anecdotal information from various sources on historical activities.

A number of these sites were the subject of the Stage 1 Assessment completed in April 2005 by ERM.

Since completion of Stage 1 assessments in April 2005, the Defence riskassessment protocols have been revised under the guidance documentpublished in July 2005. The selected sites are to be amended initially at Stage1 under this current project to confirm the risk ranking under the newprotocol.

The risk ranking attributed to each CSR entry is used as a decision makingtool for implementation of associated management options includingremediation strategies where identified.

This programme of assessment is currently being progressed across manysites by a number of different consultants. The risk assessment protocol, and the appointment of technical Advisers to the projects provides for a nationalconsistency in dealing with contamination issues ensuring that Defence canhave confidence in the decisions made.

1.2.3 CSR Sites at RAAF Tindal

Those sites at RAAF Base Tindal currently listed on the Defence database arelisted in Table 1.1 below. The risk level assigned to each site has been derivedusing the former Defence Risk Assessment Protocol and has been establishedeither by Defence or as the result of the Stage 1 Investigation completed byERM in 2005.


Page 328 of 4750

of 4750


1.5

1.3 TARGET SITES INVESTIGATED UNDER THIS COMMISSION

Of the CSR sites listed in Table 1.1 only selected issues were taken forward toStage 1 or Stage 1 and 2 investigations under this commission as set out in the table below.

Table 1.2 Scope of Assessment Work Completed Under This Commission.

CSRReference

SiteDescription

Stage of Work to Be

Completed(Tender

RequirementNov 2005)

Actual Stage of Work Completed

Rationale

NT0046 Burial/Landfill Sites

2 1 The weather conditions encountered during the period of the fieldworks precluded investigation in these areas.

NT0047 Landfill (green and otherwaste)

1 1 Stage 1 completed as proposed however, the weather conditions during the wet season precluded access for intrusive investigation.

NT0048 WasteDisposal nearold hangararea


NT0049 Wastedisposal nearSAR


NT0050 WasteDisposal nearordnancepreparationarea


NT0051 Hornet aircraftand tacticalunmannedaerial vehicleburial site



Page 330 of 4750


1.6

NT0052 Ordnance andexplosivedetonationarea nearquarry


NT0053 UST Motortransportoperationfacility

2 2 Completed as proposed.

NT0054 UST Canteen 2 2 Completed as proposed.

NT0061 Sewagetreatmentponds


NT0064 Fire TrainingArea


NT0066 Groundequipmentmaintenanceworkshops

1 2 This site is located within MEOMS (NT0072). The site was included to take advantage of the synergies realised by undertaking a holistic approach to this part of the RAAF Base.

NT0069 KatherineAirport

1 1 Completed as proposed although issues relating to access and ownership precluded the site being taken forward to any further stage.

NT0070 Batterychargingbuilding

1 2 This site is located within MEOMS (NT0072). The site was included to take advantage of the synergies realised by undertaking a holistic approach to this part of the RAAF Base.

NT0071 Old HangarArea


NT0072 322CSSMaintenanceArea

2 2 Completed as proposedand given discrete CSR Reference NT0259.


Page 331 of 4750


1.7

NT0072 322 GeneralengineeringSectionWorkshops

1 2 Completed as proposed and given discrete CSR Reference NT0260.

NT0076 Fuel Farm 1 2 2 Completed as proposed.

NT0077 Fuel Farm 2 2 2 Completed as proposed.

NT0079 AST SercoDepot


None NorForce/ICLS Depot


The final scope of investigation and assessment undertaken at each site wasagreed with the Defence Project Manager and the Technical Adviser.

The sites which were only taken to Stage 1 Assessment at this time asidentified in Table 1.2 above are the subject of a separate report prepared byERM.

The sites for which a full Stage 1 and 2 Investigation have been undertaken,and are considered in this report, are summarised in the following table.

Table 1.3 Areas of Investigation for Stage 1 and 2 Site Investigations Under this Report

CSRNumber

Details Assigned Risk Level(April 2005).

NT0064 Fire training Ground high

NT0054 UST Canteen medium

NT0076 Fuel farm 1 low

NT0077 Fuel farm 2 high

NT0072 MEOMs Area (inclusive of the following 5 maintenance areas) high

NT0053 UST Motor Transport Operation Facility high

NT0066 Ground Support Equipment maintenance workshops high

NT0070 Battery Charging Building high

NT0259 Special Purpose Vehicles high

NT0260 Tanker Maintenance Facility high

In general, only high risk sites were selected to be taken straight to a Stage 2Assessment. This included the high risk sites identified by ERM in April 2005 including the Fire Training Area, the Fuel Farm 2 and the MEOMS facility.Whilst it was recognised that a number of the features considered under the


Page 332 of 4750


1.8

Fire Training Area were potential of less significant risk, the opportunity toinvestigate these during this phase of work was taken to take advantage of the synergies that could be realised by approaching this are holistically.

The inclusion of Fuel Farm 1, which was assigned a Low Risk Level in 2005,was undertaken for comparative purposes with Fuel Farm 2. Similarly, theUST canteen was included despite being a medium risk for comparativepurpose with the Motor Transport facility where significant impacts havebeen reported previously.

The location of the areas of investigation for Stage 1 and 2 investigations arepresented on Figure NT.TIN.002, in the Attachment at the end of Section 4.0.

1.4 PROJECT GOALS AND OBJECTIVES

The Stage 2 Environmental Investigations represent an element of theDepartment of Defence risk management strategy. The project goals andobjectives relate to the assessment of potential risks to Defence capability and human health and the environment both on-site and off-site. As the facilitiesunder investigation are to continue under Defence use, the ultimateconsideration relates potential impacts under current usage (refer Section 3.0for description of current site use).

As such, whilst there is a clear desire to identify, and as necessary manage orremediate, existing contamination issues in order to mitigate associated risksto human health or the environment, the works are also required to identifyimprovements that can be made to site activities to minimise the potential for future impacts. Both outcomes will be pursued to a level consistent withDefence duty of care to the environment and delivery of Defence capability at any given time.

The current programme of environmental investigation being undertaken atfacilities across the country, of which this package of works comprises justone component, is being implemented by the Department of Defence National Contamination Unit in Canberra to ensure a risk based approach is applied to the investigation and assessment process in order to deliver consistentoutcomes.

The success of this project can be measured in terms of delivery against thefollowing objectives:

Verify the nature and extent of anticipated areas of contaminationidentified from the Stage 1 Assessment Programme for the specified sites.

Build and develop a holistic understanding of the fate and transportmechanisms at the site which preferentially act to facilitate the migration of contaminants through the various environmental media to impact on-siteand off-site receptors.


Page 333 of 4750


1.9

Establish the “true risk” to Defence from contamination identified at eachof the sites allowing the risks to be ranked and the issues prioritised.

Identify and develop optimum management strategies for each siteincorporating, as required, remediation strategies which will effectivelymitigate the identified risks to Defence.

Provide a permanent record of the works in “useable” reports that presentthe data collected, the output from the data evaluation, the contaminationsources, migration mechanisms and receptors (Conceptual Site Models),the results of qualitative and quantitative risk assessments of thecontamination issues together with proposed management options(incorporating remediation strategies as required).

Provide a permanent groundwater and surface water monitoring networkto review current and future groundwater/surface water quality,considering impacts in the vicinity of contamination areas and at siteboundaries (to identify any cross boundary issues), and reflecting the range of catchments present at each site.

1.5 STRUCTURE OF THIS REPORT

The report has been structured to present the information behind thedecisions made at each Stage in the investigation process and in this waydocument the development from the original Stage 1 Investigation (ERM2005) through the current Stage 1 and Stage 2 Investigation. As such, thereport is structured as follows:

Section 2.0 Scope and Methodology: This section of the report provides anoutline of the methodology implemented under the general approachdescribed. The section discusses the methodology for Stage 1 and Stage 2separately. A discussion on the selection of assessment criteria and theapplication of the defence risk assessment protocols is also presented in thissection.

Section 3.0 Tindal Site Description: This section provides general backgroundinformation on the Tindal site including current site use and layout, historical development and environmental setting.

Section 4.0 Groundwater Monitoring: A number of monitoring wells wereinstalled across Tindal to supplement those targeted to consider the specificCSR sites. This was undertaken to provide a network of monitoring wellsacross the catchment to allow future assessment of groundwater quality at the barracks. The general information is presented before discussions of thespecific CSR sites in subsequent Sections as the information gathered isrelevant to the interpretation and assessment of the data at each site.


Page 334 of 4750


1.10

Section 5.0 to Section 9.0: CSR Assessments: Each of the following four sections is dedicated to the complete discussion of a single or group of CSR areas ofinvestigation. The sections provide a detailed background to the site use,history and environmental setting, establishes a Conceptual Site Model andpresents the Stage 1 Risk Assessment. Based on the results of this riskassessment the decision on whether to take the site forward to Stage 2 ispresented and discussed. Where Stage 2 Environmental Investigations arejustified, the scope, rationale and findings are presented within the relevantsection. Based on these findings the section presents the results of the Stage 2 Risk Assessment together with a consideration of the potential managementoptions available to mitigate the identified risks. Supporting figures, borelogs and data tables relevant to each of these sections are included as attachmentsto the sections. In this way, relevant information for each individual CSR orgroup of CSRs can be extracted from the report without requiring the entiredocument to be reproduced.

Section 10.0: Recommendations & Summary of Outcomes: This sectionpresents a summary of all recommended management options at each CSRand provides a comparison of the Risk Band and Risk Level to demonstratethe risk reduction that can be achieved following implementation of therecommendations.

Section 11.0: Limitations Exceptions of Assessment: This section presents thelimitations of the investigation with respect to interpreting and using theresults.

Section 12.0: References

The annexes are included after Section 12.0. These include the standardoperating procedure for the field works (methodology), the ContaminationRisk Assessment Guidelines, the analytical certificates provided by thelaboratory and the results of the analytical data validation assessment.


Page 335 of 4750


2.1

2 STAGE 1 AND 2 GENERAL SCOPE AND METHODOLOGY

2.1 GENERAL PROCEDURE

The general procedure developed by ERM is illustrated in the flow chartdescribed on Figure NT.TIN.003 provided in the Attachment at the end ofSection 4.0. The procedure described in the chart is consistent with theapproach described in the NEPM and the outcomes required under thestatement of requirements provided by Defence at the tender Stage.

The scope and methodology undertaken to implement this approach for eachof the target sites includes Stage 1 and Stage 2 investigations and is describedin more detail in the following sections. This approach has been applied to all sites considered in this report however, it should be appreciated that only site NT0054 was not included in the previous Stage 1 assessment undertaken byERM in 2005.

2.2 STAGE 1 SCOPE OF WORKS AND METHODOLOGY

The Stage 1 scope of works included the following:

Data review including previous reports;

Interviews with site personnel;

A site inspection;

The review of historical records and photos where available;

The identification of chemicals of concern based on current and historic site activities;

The development of a conceptual site model (CSM) to assess viableexposure pathways and development of the risk assessment process;

Risk assessment carried out in accordance with Defence Risk AssessmentProtocol; and

The development of a sampling analysis plan (SAP) based on results of risk assessment and Stage 1.

2.2.1 Reports and Data Reviewed

An electronic copy of documents and previous reports relevant to RAAF Base Tindal were provided by the NT/K CSI group. This data included some 653files (76 folders) containing correspondence, reports, letters, e-mails/communications, notes and information relevant to contamination issues and


Page 336 of 4750


2.2

development at RAAF Base Tindal. The information reviewed included thefollowing reports, considered particularly relevant to this assessment:

HLA- Envirosciences Pty Ltd, RAAF Base Tindal, Water QualityInvestigation 2002-2003

HLA- Envirosciences Pty Ltd, RAAF Base Tindal, Water QualityInvestigation 2003-2004

Sinclair Knight Merz, Environmental Management Plan for RAAF BaseTindal, 19th July 2001, Ref. DNR04674

SKM, Phase 1: Initial Environmental Review (IER) for RAAF Base Tindal,17 August 2000

SKM, Phase 3 Environmental Management Plan for RAAF Base Tindal,Final, DR04674, 19 July, 2001

SKM, Phase 3 Environment and Heritage Strategy/Implementation Planfor RAAF Base Tindal, Draft 2 DR04674, 16 May, 2001

URS, Contamination Investigation, Fire Testing Area, RAAF Base Tindal,URS, 14 June 2002

SKM, EMS Development Phase 1 Environmental Review Report RAAFBase Tindal, Draft, 28 January 2005

ERM, Stage 1 Environmental Investigation, RAAF Base Tindal, NorthernTerritory, 2005

2.2.2 Desktop Site History Review and Site Reconnaissance

Initial Stage 1 investigations were carried out selected High Risk Sites on the19-20th April 2005. Stage 1 site inspections conducted as part of the Stage 2Project were carried out in January and February 2006. Defence personnelwere interviewed during and post the site visits.

The objectives of the desktop Site History Review were to provide a sitehistory review that identified potentially contaminating activities that havebeen performed on the site in the past or are currently being performed on the site and describe the potential Areas of Environmental Concern (AECs) andassociated chemicals of concern (CoCs).

The desktop Site History Review included the following:

Review of previous investigations (including the initial Stage 1investigation results) and reports related to the site;

Review of historical files, records and aerial photographs related to the site;


Page 337 of 4750


2.3

Interviews with previous owners/ personnel at the site and relevantpersons;

Review and summary of relevant State/ Local Government records andavailable information; and

Data assessment

The site history review prepared by ERM was based on the following:

Interviews with current site managers and personnel

Review of previous and current activities

A historical title information (where available);

A review of DoD records on the site;

A review of historical aerial photography over the past 40-50 years;

A review of groundwater records;

A review of a preliminary water investigations on the site;

Site visits/ inspections.

2.2.3 Identified Areas and Chemicals of Concern

The aim of this Stage of assessment was to identify specific areas ofenvironmental concern (AEC) and identify associated potential chemicals ofconcern (CoC) at the selected CSR sites based on the previous use of the siteand the conditions observed during the site visit.

2.2.4 Conceptual Site Model

The development of a conceptual site model was included in the Stage 1Environmental Investigation in order to better describe and identify potentialsensitive environmental and human receptors and associated potentialexposure pathways.

A CSM is the qualitative description of all plausible mechanisms by whichreceptors may be exposed to site contamination. For exposure to beconsidered possible, some mechanism (‘pathway’) must exist by whichcontamination from a given source can reach a given receptor. Such complete ‘source-pathway-receptor’ exposure mechanisms are commonly termed‘pollutant linkages’. Exposure via these pollutant linkages is quantified andevaluated at later stages in the assessment. Pollutant sources, exposuremechanisms and receptors at the site are discussed below.


Page 338 of 4750


2.4

Potential exposure pathways are evaluated for completeness based on theexistence of:

A source of chemical contamination;

A mechanism for release of contaminants from identified sources;

A contaminant retention or transport medium (e.g. soil, air, groundwateretc.);

Potential receptors of contamination; and

A mechanism for chemical intake by the receptors at the point of exposure (i.e. ingestion, dermal contact or inhalation).

Whenever one or more of the above elements is missing, the exposurepathway is incomplete and there is therefore no risk to human health forexample. An exposure pathway can be either “direct”, where the receptorcomes into direct contact with the affected environmental media (eg. soilingestion) and “indirect”, where exposure occurs at a different location or in a different medium than the source (eg. soil vapours volatilising to ambient air).

2.2.5 Stage 1 Risk Assessment

A risk assessment of issues identified upon completion of the Stage 1Environmental Investigation has been undertaken in accordance with theDefence Risk Assessment Protocol. The methodology is described in Section2.5.

2.2.6 Sampling and Analysis Plan

The results of the desk top site history review were use to develop samplingand analysis plans (SAPs) for each site where risk levels indicated that further investigation was required. The objective of the SAP was to provide asampling and analysis plan for consideration by the DoD for Stage 2. TheSAP’s were developed and refined with consideration of the following:

The sampling strategy;

Sampling density; and

Sampling frequency.

Based on the proposed use of the site to continue as an operational Defencefacility and the findings of the site history review, ERM considered that acombined targeted soil sampling and groundwater sampling plan wasappropriate for the site. The combined targeted soil sampling andgroundwater monitoring program was proposed to assess the potential


Page 339 of 4750


2.5

impacts of identified activities on the site and sensitive receptors and toprovide an ongoing means of assessment.

The sampling strategy included consideration of the identified areas ofconcern and a combination of targeted and stratified sampling. The selectedsampling density and frequency for each site was determined based on thepotential extent and delineation of impacted soil/water and sediment. TheSAPs were reviewed by a DoD appointed third party technical reviewer.

A targeted sampling (judgemental sampling) program was recommended forthis site to allow for assessment of specific locations identified where (basedon the site history) there is considered a higher probability of contaminationoccurring that may present a risk to the environment or site users.

As far as possible, groundwater monitoring wells was designed to focus ondown gradient areas, however, it should be appreciated that the location ofthe wells was based on assumptions of likely groundwater regime as nodetailed groundwater data was available during the Stage 1.

2.3 STAGE 2 GENERAL SCOPE OF WORKS AND METHODOLOGY

The general scope of works involved in the Stage 2 investigations included the following:

The development/ refinement of the sampling and analysis plan,following third party technical review;

Development of project support documentation and procedures, includingStandard Operating Procedures (SOPs), a Health and Safety Action Plan(HASAP), an Environmental Management Plan (EMP) andCommunications Plan;

Implementation of soil, groundwater (and surface water as appropriate)and sediment sampling programme to assess potential site contaminationimpacts from site activities and historical site use. Works executed inaccordance with the ERM Standard Operating Procedures Annex A;

Analyses of soil, groundwater (and surface water as appropriate) andsediment samples based on identified chemicals of concern;

Assessment of analysis results against selected criteria;

Stage 2 risk assessment based on site investigation results, and

The development of management and/or remediation recommendationsbased on results.

The risk assessment of issues identified in the refined CSM developed uponcompletion of the Stage 2 Environmental Investigation was undertaken in


Page 340 of 4750


2.6

accordance with the Defence Risk Assessment Protocol. The methodology isdescribed in Section 2.5.

The CSM was refined based on the observed ground conditions (particularlythe established groundwater regime) confirmation of the identified receptorsand establishment of a viable source of impact by the identified chemicals ofconcern. The analytical results for soil and groundwater were comparedagainst available published guideline criteria for soil and groundwater toidentify sources of impact.

A range of guideline criteria are available for considering concentrations of arange of analytes soil and groundwater soil and groundwater for a range ofdifferent exposure scenarios. These guidelines generally provide genericcriteria which are not site specific and are inherently conservative. As such,further studies and derivation of site specific criteria can be undertaken toreduce the conservatism and produce criteria appropriate to specific exposure scenarios and site settings where exceedences are identified; however, in most instances the initial screening provides an adequate level of assessment toallow a refined assessment of the true risk to defence to be established.

The selection of guideline criteria are discussed in the following section.

2.4 SELECTION OF ASSESSMENT CRITERIA

The assessment of the analytical data is achieved through comparison of theresults against published assessment guidelines for different environmentalmedia such as soil or water. This assessment provides a preliminaryidentification of potential issues.

Published Australian guidelines have been adopted for this project. However, where required standards were unavailable, guideline values from othercountries including the United States, Canada, UK/EU and preferred sources(e.g. World Health Organisation, USEPA), have been sought to assist in theassessment of particular compounds in sampled environmental media.

Guidelines considered for the assessment of the target sites are presented inthe following sections. Analytes with no readily available published guideline value are highlighted for further investigation depending on analyticalresults.

Justification for selection of specific criteria at each site is presented in the CSR Chapters.

Soil Assessment Criteria

Soil sample analysis results have been compared to available SoilInvestigation Levels in Schedule B (1) of the NEPM and based on Schedule B(7A) and Health Investigation Levels for Commercial or Industrial Use sites.


Page 341 of 4750


2.7

National Environment Protection (Assessment of Contaminated Sites)Measure (1999), Schedule B (1) Guideline on the Investigation Levels forSoil and Groundwater. Commercial and Industrial Land Uses – HealthInvestigation Level F.

Additional criteria have been used for Total Petroleum Hydrocarbons andbenzene as follows:

QLD EPA guidelines for the assessment of Total Petroleum Hydrocarbonconcentrations; and

NSW EPA (119) Guidelines for Assessing Service Station Sites for benzene.

In general, NEPM Environmental Investigation Levels (EIL’s) for soil have not been used in the assessment as EIL’s are not considered suitable criteria forthis assessment due to the generally low ecological sensitivity in theimmediate vicinity of the specific target CSRs on the base. However, it isrecognised that the wider environment around RAAF Tindal does represent a more sensitive ecological system. In this regard, ecological consideration isaddressed by considering impacts to the aquatic environment throughconsideration of concentrations of chemicals of concern in groundwater andsurface water (see below).

Groundwater Assessment Criteria

The following available guideline criteria have been adopted to considerissues in terms of aquatic ecosystems and human health.

National Environment Protection (Assessment of Contaminated Sites)Measure (1999), Schedule B (1) Guideline on the Investigation Levels forSoil and Groundwater. (i.e. ANZECC/ARMCANZ, 2000). Australian andNew Zealand Guidelines for Fresh and Marine Waters; and

NHMRC/ARMCANZ (2004) Australian Drinking Water Guidelines.

A discussion on the site setting is presented in Section 3.0, however, it is noted that the Tindal aquifer is used regionally as a source of drinking water andthat there are provisions to use some abstraction points on the base forproviding a drinking supply. In addition, all surface water drainageultimately discharge to Tindal Creek and it is anticipated that groundwaterflow will also be in hydraulic continuity with this surface water receiver

On this basis, results of groundwater analysis are considered in the context of both the drinking water standards and fresh water criteria however, theadopted assessment criteria are presented in the tabulated data included ineach CSR section and a statement in the selection of assessment criteria is also presented in each CSR chapter.


Page 342 of 4750


2.8

Sediment Assessment Criteria

The ANZECC/ARMCANZ Interim Sediment Quality guidelines werepublished in 2003 to provide a preliminary mechanism for assessing sediment quality in terms of chemical testing. The guidelines consider exposure ofbenthic fauna (e.g. sediment/bottom feeding fauna).

The guidelines are published for a limited suite of chemicals and are designed to provide a preliminary stage in a tiered approach to sediment assessmentwhich can also include toxicity testing. The guidelines have been adoptedhere to provide a preliminary screening of sediment results.

2.5 DEFENCE RISK ASSESSMENT PROTOCOL

Defence’s Contamination Risk Assessment Guidance has been used to assessthe risks associated with the sites investigated. This risk assessment approach has been developed to be expressly used in conjunction with Stage 1 , Stage 2and Stage 3 site investigations on Defence sites using the NationalEnvironment Protection (Assessment of Site Contamination) Measure 1999(NEPC, 1999) risk based approach. A copy of the risk assessment guidancedocument is included in Annex B.

The methodology provides an approach which can consider risks for each CSR site in the context of “Risk Dimensions” which are of importance to Defence.Risk can be considered in terms of these dimensions which are identified as:

Capability;

Occupational Health andSafetyy (Staff and Public);

Legislative Compliance;

Environment and Heritage;

Financial Efficiency;

Personnel; and

Reputation.


Page 343 of 4750

of 4750


2.2

Table 2.2 Stage 1 and 2 Site Investigation Personnel

InvestigationDates

Personnel Role/Expertise

Primary Project Team

Jan-July 2006Feb-July 2006March-May 2006March-May 2006Feb-July 2006May-June 2006March-May 2006March-May 2006

Additional Technical/Support Personnel

May 2006May 2006April-May 2006


s47G

s47G

Page 345 of 4750


3.1

3 RAAF BASE TINDAL – GENERAL SITE DESCRIPTION

3.1 BASE LAYOUT AND FUNCTIONS

The RAAF Base Tindal is located approximately 320km south east of Darwinand around 13km south east of the township of Katherine in the NorthernTerritory. RAAF Base Tindal contains the following main site features andstructures as illustrated on Figure NT.TIN.004, in the Attachment at the end ofSection 4.0.

Defence Personnel Service Facilities:

Married Quarters (north side, approximately 3km south of the StuartHighway)

Messes and football oval (south of the married quarters)

Frontline Canteen & Service Station (west of the married quarters)

Golf Course (south-west of the married quarters)

Sewage Treatment Plant & Horse Paddock (effluent irrigation area, farsouth west of site)

Vehicle Maintenance, Workshops and Storage Areas:

Hazardous Materials Storage and

Ordnance Storage (West of Golf course)

Ordnance Loading Aprons (either side of former Stuart Highway)

75 Squadron workshops and QA/QC labs

Other ordnance preparation and storage areas

Dog Complex (east of the golf course, south of married quarters)

Other Defence Operational Facilities:

Fuel Farm No. 2 and Fuel Farm No. 1

RAAF Air movements

Civilian Airport

Fire Brigade and Search and Rescue Section

Fire Training Area


Page 346 of 4750


3.2

3.1.1 Current and Proposed Facility Activities

RAAF Base Tindal currently operates as a joint civil-military airfieldemploying some 600 military and civilian personnel. The primary role ofRAAF Base Tindal is to provide an operational base for 75 Squadron whichforms part of the Air Force’s Tactical Fighter Force.

RAAF Base Tindal as it exists today was first established in 1987 and iscurrently under the control of 322 Combat Support Wing (322 CSW). The Hill 202 Radar Facility, also established in 1987 is located approximately 4 km east of Tindal.

There are a number of activities undertaken at Tindal which include (but arenot limited to) the following:

Ordnance preparation, storage and assembly;

Refuelling of vehicles and aircraft;

Aircraft maintenance, washing and painting;

Fuel testing;

Light engineering works (vehicle maintenance, welding, aircraft engineworks and body works, including painting);

Security, including police dog training;

Radar communications;

Medical facilities;

Catering;

Photography of aircraft and personnel (and photo processing);

Fire fighting services;

Accommodation;

Ground defence training;

Search and rescue (SAR) undertaken by contractors Lloyds;

Lease of land to Frontline who run a canteen and service station for private use by Base personnel and the public;

Lease of land to Katherine Town Council who manage the KatherineAirport; and

Air movements of military passengers and cargo.


Page 347 of 4750


3.3

3.1.2 Future/ Proposed Land Uses

It is understood the Base is likely to undergo redevelopment and expansion as a priority Defence establishment. The site is therefore likely to continue to beused in its current form. It should be noted that although RAAF Tindal isconsidered an operational Defence facility, and may be categorised as acommercial/ industrial land use, the presence of Defence accommodation and residential housing on the base constitutes a potentially more sensitive landuse, and this is therefore taken into account in the selection of assessmentcriteria and risk assessment where this is relevant to the individual CSR under consideration. These more sensitive land uses are identified in the individual CSR sections.

3.2 GEOLOGY AND SOILS

The 1:250,000 Geological Map Series for Katherine SD 53-9, 1994 describes theregional geology of the Tindal area as belonging to the Daly Basin dominated by lowland plains, and consisting of limestone, mudstone, dolostone andminor sandstone deposited in peritidal to open shelf marine environments.Quaternary laterite ferricrete and residual loamy sands overlay the limestonein much of the Tindal area.

Geology and soils information reported in previous assessments (SKM, 2001)describes the Tindal area as belonging to the Cambrian land system, which isan area of extensive stony erosional plains. These erosional plains arecharacterised by loamy red earths, with the occasional limestone outcrops,scattered sinkholes, shallow depressions and stream channels incised inbedrock. A number of soil groups have been identified in the Tindal area, and include the following broad groups (in order of occurrence):

Red earths - sandy and loamy red earths derived from silicified sandstoneand limestone;

Earthy sands - dark-reddish brown, loose, clayey sand profile and aregenerally well-drained;

Yellow earths - similar to red earths but tend to become water loggedduring the wet season;

Lateritic podzols (used extensively as borrow pits during the constructionof RAAF Base Tindal)

Lithosols - containing high amounts of rock fragments and confined toareas where rock outcrops are common;

Grey-brown clays - clay textured soils that crack widely and are very dry.


Page 348 of 4750


3.4

3.3 HYDROGEOLOGY

Information provided by the Northern Territory Department of Infrastructure, Planning and Environment (Conservation and Natural Resources Group – DIPE), for the Daly River Catchment Aquifer Formation is summarised asfollows (The DIPE publication is reproduced as Figure NT.TIN.005, in theAttachment at the end of Section 4.0:

The Tindal and Katherine region is underlain by the Daly River formationknown throughout the region as ‘Tindal Limestone’.

The limestone aquifer is a generally deep unconfined aquifer ranging indepth from the surface (in the Katherine River area) down toapproximately 650m AHD around 50km south west of Katherine.

The Tindal Limestone aquifer is thought to be over 100km wide and over300km long.

Perched above the Tindal limestone aquifer is the Jinduckin formation,however the Limestone aquifer is observed close to or at the surface inmany locations within the Tindal area.

Significant groundwater flow towards the Daly River Catchment Area and the Tindal Limestone Aquifer has been noted at estimated flow rates of 90-180ML/day.

Tindal Creek is understood to flow into the Katherine River, which is animportant drinking water source for the local community and surrounding area. The Tindal Limestone Aquifer also provides base flow to theKatherine River.

The DIPE publication suggests that groundwater flow in the region of RAAFTindal is reported as being towards the Katherine River to the north west (atan estimated flow rate of 90-180ML/day).

3.3.1 Groundwater Usage and Records

The Northern Territory Department of Infrastructure, Planning andEnvironment (DIPE) maintain a register of groundwater bores in NorthernTerritory. A search of NT DIPE records of monitoring bores within a 2kmradius of the site revealed the following list of bores (yielding 0.1L or more).


Page 349 of 4750

of 4750

1 of 4750


3.7

monitoring events. A copy of the gauging data provided is included in AnnexC.

A number of these bores are currently used for irrigation purposes with meter records reported for Bores 1, 2, 21, 20 and 27 (Annex C). No abstraction isreported from any of the other bores at the site.

It is also understood that bores located on the base, including a bore locatedon the golf course (Bore 2) can provide a domestic supply in emergencysituations (Reported by SKM, August 2000).

It is understood Spotless undertake sampling of water samples from selectedbores identified in Figure NT.TIN.007, Attachment 1. Results from analysis forTindal Bores for “Bacteriological Analysis” and “Physical – ChemicalAnalysis” were provided to ERM during site visits in February 2006. Theresults relate to samples collected from the bores in 2005. Copies of the dataprovided are included in Annex C.

The results indicate that coliform counts were detected in a number of boresacross the site and are flagged as failing the test in respect of the adoptedassessment criteria. Failures reported included the Golf Club Bore, Bore 2,which is reportedly available to provide emergency supply (see above).

The presence of the unconfined Tindal Limestone Aquifer beneath Tindal that feeds into the Katherine River which in turn provides a source of drinkingwater for the township of Katherine, represents a potential pathway for soiland/or water contamination to reach sensitive environmental and humanreceptors. The presence of numerous groundwater bores down-gradient of the base also presents a potential exposure pathway and on that basis presents apotential risk to Defence.

3.3.2 Surface Water and Drainage

The dominant surface water near RAAF Base Tindal is Tindal Creek (alsoreferred to as Four Mile Creek) which flows from the south of the base westnorth-west towards Katherine. The creek passes south of the runway, crosses the Stuart Highway twice between Tindal and Katherine and is understood to enter the Katherine River downstream of the township. The location of thecreek is shown in Figure NT.TIN.004, in the Attachment at the end of Section4.0.

Tindal Creek is ephemeral and although it has a catchment area of around 175 km2, it is understood to be dry between May and November. Stormwater run-off and drainage across RAAF Tindal is generally in the direction of the westand southwest, towards and into Tindal Creek.

The Katherine River is understood to be the primary source of potabledrinking water for Katherine and RAAF Base Tindal.


Page 352 of 4750


3.8

3.4 SURROUNDING LAND USE

The base covers an estimated area of 122 square kilometres, however much of this area is covered by mixed Eucalypt bushland and open forest and less than one twentieth of this area contains hard stand and structures.

The surrounding land use can be summarised as follows:

The site is bounded by the Stuart Highway to the north, with grazing andrural/residential land to the north (including Jarridale Station).

Partially disturbed bushland rural land and mango farms to the east andthe Township of Katherine 13km east-north east.

Cutta Cutta Caves National Park to the south.

Grazing land and a quarry, from which blue metal road base is mined, tothe west.


Page 353 of 4750


4.1

4 CATCHMENT WIDE GROUNDWATER MONITORING

The original tender for the works at RAAF Tindal included groundwater,surface water and sediment monitoring across the base to consider catchment wide and off-site issues. Due to flooding and access limitations the catchment wide monitoring program was not undertaken. However, the monitoringwells located as part of the Stage 2 investigations at the target CSR sitesprovide a wide network of wells which can be used to establish thegroundwater regime across the base.

A total of 23 groundwater wells were installed across the base at the CSRareas of investigation shown on Figure NT.TIN.003, included in the Attachmentto this chapter.

A summary of the groundwater depths and reduced groundwater levels areprovided in the table below. Field parameters and groundwater analyticalresults are presented within the following CSR sections.

Table 4.1 Catchment Wide Groundwater Gauging Data (May 2006)

Monitoring Well Depth toGroundwater

(mbtoc)

Top of Casing Level (mAHD)

ReducedGroundwater Levels

(mAHD)CSR077 MW01 1.90 131.43 129.53CSR077 MW02 1.83 131.19 129.37CSR077 MW03 2.03 131.42 129.39CSR054 MW01 8.32 143.94 135.63CSR054 MW02 8.71 144.33 135.63CSR054 MW03 9.01 144.46 135.45CSR053 MW01 8.36 143.11 134.75CSR053 MW02 8.27 142.96 134.69CSR053 MW03 8.72 142.99 134.27CSR053 MW04 8.22 142.85 134.63CSR260 MW02 9.21 143.44 134.23CSR260 MW01 8.74 144 135.27CSR066 MW01 10.32 145.24 134.93CSR070 MW01 8.51 143.29 134.78CSR070 MW02 8.62 143.42 134.81CSR259 MW01 8.97 143.72 134.76CSR072 MW01 10.59 145.43 134.85CSR076 MW01 5.49 139.7 134.22CSR076 MW02 5.39 139.46 134.07CSR076 MW03 5.62 139.29 133.67CSR064 MW01 4.46 134.07 129.62CSR064 MW02 4.81 134.42 129.61CSR064 MW03 4.56 134.29 129.731. mbtoc – metres below top of casing2. mAHD = metres relative to Australian Height Datum


Page 354 of 4750


4.2

4.1 SUMMARY OF GROUNDWATER CHARACTERISTICS

Groundwater wells were installed broadly across the primary areas of thebase with the greatest coverage over the north-eastern (MEOMS) area, thewest, north-western area, the south-western area (Fire Training Ground) andthe south-eastern area (Fuel Farm 1).

Groundwater was intercepted across the site at levels between 2 and 10mbelow ground level or approximately 129-135mAHD. Contours ofgroundwater levels are illustrated on Figure NT.TIN.009, in the Attachment atthe end of this Section, and show groundwater flow towards the west southwest at a gradient of approximately 1(vertical) in 400 (horizontal).

Groundwater flow direction was generally observed to flow towards theTindal Creek. It is noted that the observed groundwater levels represent theend of wet season (and post flood) conditions. It should be appreciated thatgroundwater levels in this environment are likely to be sensitive to significant seasonal fluctuations.

The above observations contradict the data reported by DIPE which suggestsflow in the underlying Tindal Limestone aquifer will be towards the NorthWest in the direction of the Katherine River (Section 3.2.1 and FigureNT.TIN.005).


Page 355 of 4750

RAAF Base Tindal

Attachment 1

Figures


Page 356 of 4750

of 4750

Stage 1 and 2 Environmental Investigations NT/K · 6 csr section - nt0054, ust canteen 7 csr...

Documents

Transcript of Stage 1 and 2 Environmental Investigations NT/K · 6 csr section - nt0054, ust canteen 7 csr...