RAAF Base Townsville - Seasonal Monitoring Report 1 - PFAS€¦ · 4.2 dsi csm ... 8.3.1 source area impacts..... 104 8.3.2 off-base impacts..... 107 8.3.3 interpreted plume of groundwater

DEPARTMENT OF DEFENCE

RAAF BASE TOWNSVILLE - SEASONAL MONITORING REPORT 1 - PFAS VOLUME 1: MAIN REPORT

DECEMBER 2019

PUBLIC

VOLUME 1 (this document)

GLOSSARY .................................................................................... XII

ABBREVIATIONS ......................................................................... XIV

EXECUTIVE SUMMARY ............................................................. XVII

1 INTRODUCTION ................................................................... 1

1.1 PREAMBLE................................................................................. 1

1.2 BACKGROUND .......................................................................... 1

1.3 OBJECTIVE ................................................................................ 2 1.3.1 PROGRAM STRATEGIC AIM ............................................................... 2 1.3.2 PROJECT KEY OBJECTIVES............................................................... 2

1.4 CONTEXT OF THE DSI .............................................................. 2

1.5 SCOPE OF WORKS ................................................................... 3 1.5.1 DSI ......................................................................................................... 3 1.5.2 SEASONAL MONITORING REPORT 1 ................................................ 3 1.5.3 ANALYTICAL SUITE ............................................................................. 4

2 SITE IDENTIFICATION AND BACKGROUND ................. 8

2.1 THE BASE ................................................................................... 8

2.2 INVESTIGATION AREA ............................................................. 9 2.2.1 TOWNSVILLE AIRPORT ....................................................................... 9 2.2.2 TCC AREAS ........................................................................................ 10 2.2.3 ECOLOGICAL AREA ........................................................................... 10

2.3 ENVIRONMENTAL SETTING ................................................... 11 2.3.1 TOPOGRAPHY AND PHYSIOGRAPHY ............................................. 11 2.3.2 CLIMATE ............................................................................................. 12 2.3.3 GEOLOGY ........................................................................................... 12 2.3.4 HYDROGEOLOGY .............................................................................. 14 2.3.5 GROUNDWATER USE ....................................................................... 17 2.3.6 SURFACE WATER .............................................................................. 17 2.3.7 FLOOD HAZARD ................................................................................. 19 2.3.8 SURFACE WATER – GROUNDWATER INTERACTIONS ................. 19 2.3.9 SENSITIVE LOCAL ENVIRONMENTAL RECEPTORS ...................... 20

2.4 PROPERTIES OF PFAS ........................................................... 22 2.4.1 PHYSICAL AND CHEMICAL PROPERTIES OF

PFOS/PFOA/PFHXS ........................................................................... 22 2.4.2 KEY PFAS MIGRATION PROCESSES AT THE IA ............................. 24 2.4.3 PFAS ANALYSIS AND DATA INTERPRETATION

CONSIDERATIONS ............................................................................ 24

TABLE OF CONTENTS

CONTENTS (Continued) 2.5 THE INVESTIGATION AREA, CONTAMINANT

CHARACTERISTICS AND LIMITATIONS OF THE SEASONAL MONITORING REPORT 1 ................................... 26

3 SITE HISTORY REVIEW ....................................................28

3.1 PREVIOUS INVESTIGATIONS................................................. 29

3.2 POTENTIAL IMPLICATIONS OF PFAS EXPOSURE.............. 30

4 DSI CONCEPTUAL SITE MODEL ....................................31

4.1 DEFINITION OF SOURCE-PATHWAY-RECEPTOR LINKAGES ................................................................................ 31

4.2 DSI CSM .................................................................................... 31

5 APPROACH AND METHODOLOGY ...............................34

5.1 APPROACH AND SAMPLING RATIONALE ........................... 34 5.1.1 TECHNICAL AND REGULATORY FRAMEWORK .............................. 34 5.1.2 ENVIRONMENTAL VALUES ............................................................... 35 5.1.3 RATIONALE ........................................................................................ 42

5.2 METHODOLOGY ...................................................................... 44 5.2.1 SOIL .................................................................................................... 44 5.2.2 GROUNDWATER ................................................................................ 45 5.2.3 SURFACE WATER .............................................................................. 46 5.2.4 SEDIMENT SAMPLING ....................................................................... 47 5.2.5 RESIDENTIAL BORE SAMPLING ....................................................... 47 5.2.1 RESIDENTIAL SWIMMING POOL SAMPLING ................................... 48 5.2.2 RESIDENTIAL BIOTA SAMPLING ...................................................... 48

5.3 LABORATORY ANALYSIS ...................................................... 49

6 ASSESSMENT CRITERIA .................................................50

6.1 OVERVIEW ............................................................................... 50

6.2 SOIL ASSESSMENT CRITERIA .............................................. 50

6.3 SEDIMENT ASSESSMENT CRITERIA .................................... 50

6.4 WATER ASSESSMENT CRITERIA.......................................... 51

7 RESULTS .............................................................................55

7.1 RAINFALL DURING THE SEASONAL MONITORING............ 55

CONTENTS (Continued) 7.2 SUB-SURFACE CONDITIONS ................................................. 56 7.2.1 SUB-SURFACE SOIL .......................................................................... 56 7.2.2 ON-BASE SURFACE SEDIMENT ....................................................... 57 7.2.3 OFF-BASE SURFACE SEDIMENT ..................................................... 59 7.2.1 PARTICLE SIZE DISTRIBUTION ........................................................ 62

7.3 HYDROGEOLOGY ................................................................... 64 7.3.1 RESIDENTIAL BORE USE SURVEY AND TARGET BORES............. 64 7.3.2 GROUNDWATER ELEVATION AND FLOW DIRECTION .................. 65 7.3.3 GROUNDWATER GEOCHEMICAL PARAMETERS ........................... 65 7.3.4 HYDRAULIC CONDUCTIVITY ............................................................ 66

7.4 SURFACE WATER CONDITIONS ........................................... 66 7.4.1 OBSERVED CONDITIONS – GENERAL ............................................ 66 7.4.2 SURFACE WATER HYDROCHEMICAL PARAMETERS .................... 68 7.4.3 AQUATIC BIOTA / SURFACE WATER CO-LOCATIONS ................... 70

7.5 SOIL ANALYTICAL RESULTS ................................................ 71 7.5.1 ON-BASE SOURCE AREAS ............................................................... 72 7.5.2 OFF-BASE SOIL RESULTS ................................................................ 73 7.5.3 RESIDENTIAL SOIL RESULTS ........................................................... 73

7.6 GROUNDWATER ANALYTICAL RESULTS ........................... 74 7.6.1 ON-BASE SOURCE AREAS ............................................................... 75 7.6.2 OFF-BASE ........................................................................................... 79 7.6.3 RESIDENTIAL PROPERTY EXTRACTION BORES ........................... 82 7.6.4 COMMERCIAL PROPERTY EXTRACTION BORES AND

MONITORING WELLS ........................................................................ 82 7.6.5 TOP ASSAY ........................................................................................ 83 7.6.6 HYDROGEOCHEMISTRY ................................................................... 84

7.7 SURFACE WATER ANALYTICAL RESULTS ......................... 87 7.7.1 DISCHARGE SAMPLING .................................................................... 87 7.7.2 POST-WET SEASON SURFACE WATER SAMPLING ...................... 88 7.7.3 HYDROCHEMISTRY ........................................................................... 91

7.8 SEDIMENT ANALYTICAL RESULTS ...................................... 92 7.8.1 ON-BASE ............................................................................................ 92 7.8.2 OFF-BASE ........................................................................................... 93 7.8.3 TOP ASSAY ........................................................................................ 94

7.9 BIOTA RESULTS ...................................................................... 95

7.10 QUALITY ASSURANCE AND QUALITY CONTROL .............. 95

CONTENTS (Continued)

8 DISCUSSION .......................................................................99

8.1 NATURE AND EXTENT OF SOIL IMPACT ............................. 99 8.1.1 ON-BASE SOURCE AREAS – SOIL IMPACTS .................................. 99 8.1.2 OFF-BASE SECONDARY SOURCE AREAS – SOIL

IMPACTS ........................................................................................... 100

8.2 HYDROGEOLOGY ................................................................. 101 8.2.1 THICKNESS AND EXTENT OF LOCAL AQUIFERS ......................... 101 8.2.2 GROUNDWATER RECHARGE ......................................................... 101 8.2.3 GROUNDWATER ELEVATION FLUCTUATIONS ............................ 101 8.2.4 SHALLOW GROUNDWATER/SURFACE WATER

INTERACTION .................................................................................. 102 8.2.5 HYDRAULIC CONDUCTIVITY ESTIMATES ..................................... 102 8.2.6 ESTIMATING GROUNDWATER FLOW VELOCITY ......................... 103

8.3 NATURE AND EXTENT OF GROUNDWATER IMPACT ................................................................................... 104

8.3.1 SOURCE AREA IMPACTS ................................................................ 104 8.3.2 OFF-BASE IMPACTS ........................................................................ 107 8.3.3 INTERPRETED PLUME OF GROUNDWATER IMPACTS ............... 110 8.3.4 COMPARISON OF POST-WET SEASON GROUNDWATER

RESULTS WITH PREVIOUS INVESTIGATIONS .............................. 110 8.3.5 POTENTIAL MECHANISMS OF PFAS BEHAVIOUR

EXPLAINING WET SEASON GROUNDWATER RESULTS ............. 116

8.4 NATURE AND EXTENT OF SURFACE WATER AND SEDIMENT IMPACT ............................................................... 118

8.4.1 SURFACE WATER HYDROLOGY .................................................... 118 8.4.2 SOURCE AREAS AND SURFACE WATER ...................................... 119 8.4.3 PFAS MIGRATION TO SURFACE WATER ...................................... 120 8.4.4 SIGNIFICANT RAINFALL EVENT DISCHARGE ............................... 121 8.4.5 NATURE AND EXTENT OF SURFACE WATER AND

SEDIMENT IMPACT .......................................................................... 122 8.4.6 TEMPORAL VARIATION IN SURFACE WATER AND

SEDIMENT ........................................................................................ 126

9 CONCEPTUAL SITE MODEL ........................................ 129

9.1 INTRODUCTION ..................................................................... 129

9.2 PFAS CONTAMINANTS OF POTENTIAL CONCERN .......... 129

9.3 SUMMARY OF SOURCES OF CONTAMINATION ............... 129

9.4 MIGRATION PATHWAYS ...................................................... 130

9.5 EXPOSURE PATHWAYS ....................................................... 131

9.6 POTENTIAL RECEPTORS ..................................................... 132

CONTENTS (Continued) 9.7 SUMMARY OF SOURCE-PATHWAY-RECEPTOR

LINKAGES .............................................................................. 132

9.8 AREAS OF UNCERTAINTY ................................................... 138 9.8.1 SOIL ASSESSMENT ......................................................................... 138 9.8.2 GROUNDWATER ASSESSMENT .................................................... 138 9.8.3 SURFACE WATER AND SEDIMENT ASSESSMENT ...................... 139 9.8.4 BIOTA ................................................................................................ 139 9.8.5 PROPOSED FURTHER ASSESSMENT ........................................... 139

10 CONCLUSIONS ............................................................... 140

10.1 SITE SETTING ........................................................................ 140

10.2 PFAS SOURCES (SOIL) ........................................................ 140

10.3 GROUNDWATER ................................................................... 141

10.4 SURFACE WATER AND SEDIMENTS .................................. 141

10.5 BIOTA ...................................................................................... 142

10.6 COMPARISON OF DRY AND WET SEASON PFAS CONCENTRATIONS ............................................................... 142

10.7 CONCEPTUAL SITE MODEL ................................................. 142

10.8 ONGOING WORKS ................................................................ 143

11 LIMITATION STATEMENT: ENVIRONMENTAL SITE ASSESSMENT ....................................................... 144

12 REFERENCES ................................................................. 146

LIST OF TABLES TABLE 1.1 DQO PROCESS ............................................................................ 6 TABLE 2.1 SUMMARY OF GENERAL BASE INFORMATION ........................ 8 TABLE 2.2 SUMMARY OF GENERAL TOWNSVILLE AIRPORT

INFORMATION ............................................................................. 9 TABLE 2.3 REGISTERED GROUNDWATER MONITORING

BORES WITHIN THE IA .............................................................. 15 TABLE 2.4 CHEMICAL AND PHYSICOCHEMICAL PROPERTIES

OF PFOS, PFOA AND PFHXS .................................................... 23 TABLE 2.5 POTENTIAL UNCERTAINTIES IN PFAS ANALYSIS

AND INTERPRETATION ............................................................. 24 TABLE 2.6 CHARACTERISTICS OF POTENTIAL LIMITATIONS

AND STRATEGIES EMPLOYED ................................................ 26 TABLE 4.1 DSI CSM ..................................................................................... 31 TABLE 5.1 PRESCRIBED WATER ENVIRONMENTAL VALUES

WITHIN THE IA ........................................................................... 35 TABLE 5.2 SANDY FRESHWATER AQUIFER ENVIRONMENTAL

VALUES ...................................................................................... 36 TABLE 5.3 CLAYEY SALINE AQUIFER ENVIRONMENTAL

VALUES ...................................................................................... 39 TABLE 5.4 SURFACE WATER ENVIRONMENTAL VALUES ....................... 41 TABLE 5.5 SAMPLING RATIONALE ............................................................. 42 TABLE 5.6 SOIL ASSESSMENT METHODOLOGY ...................................... 44 TABLE 5.7 GROUNDWATER ASSESSMENT METHODOLOGY ................. 45 TABLE 5.8 SURFACE WATER ASSESSMENT METHODOLOGY ............... 46 TABLE 5.9 SEDIMENT SAMPLING METHODOLOGY ................................. 47 TABLE 5.10 RESIDENTIAL BORE SAMPLING METHODOLOGY ................. 47 TABLE 5.11 SWIMMING POOL SAMPLING METHODOLOGY ...................... 48 TABLE 5.12 BIOTA SAMPLING METHODOLOGY ......................................... 48 TABLE 6.1 SOIL INVESTIGATION LEVELS ................................................. 53 TABLE 6.2 GROUNDWATER INVESTIGATION LEVELS............................. 54 TABLE 6.3 SURFACE WATER INVESTIGATION LEVELS .......................... 54 TABLE 7.1 RAINFALL DURING FIELDWORK – SEASONAL

MONITORING FIELDWORKS WERE UNDERTAKEN IN MARCH 2018 – SEPTEMBER 2018 ........................................... 55

TABLE 7.2 INGHAM ROAD SPORTS FIELDS OBSERVED SOIL LITHOLOGY SUMMARY ............................................................. 56

TABLE 7.3 GARBUTT COMMUNITY OBSERVED SOIL LITHOLOGY SUMMARY ............................................................. 56

TABLE 7.4 PALLARENDA OBSERVED SOIL LITHOLOGY SUMMARY .................................................................................. 56

TABLE 7.5 ROWES BAY OBSERVED SOIL LITHOLOGY SUMMARY .................................................................................. 57

LIST OF TABLES (CONTINUED) TABLE 7.6 BASE SEDIMENT SAMPLE ID AND LITHOLOGY

SUMMARY .................................................................................. 57 TABLE 7.7 CLEVELAND BAY (THREE MILE CREEK

CATCHMENT) SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ............................................................. 59

TABLE 7.8 ROWES BAY & BELGIAN GARDENS (MUNDY CREEK CATCHMENT) SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ............................................................. 59

TABLE 7.9 GARBUTT (MUNDY CREEK CATCHMENT) SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ................................ 60

TABLE 7.10 GARBUTT (LOUISA AND PEEWEE CREEK CATCHMENT) SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ............................................................. 60

TABLE 7.11 BOHLE RIVER SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ............................................................. 61

TABLE 7.12 TOWN COMMON (LOUISA CREEK CATCHMENT) SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ............. 61

TABLE 7.13 BACKGROUND LOCATIONS (STUART AND ALTHAUS CREEK CATCHMENT AND ROSS CREEK CATCHMENT) SEDIMENT SAMPLE ID AND LITHOLOGY SUMMARY ............................................................. 62

TABLE 7.14 SUMMARY OF ON-BASE PARTICLE SIZE DISTRIBUTION RESULTS .......................................................... 62

TABLE 7.15 SUMMARY OF OFF-BASE PARTICLE SIZE DISTRIBUTION RESULTS .......................................................... 63

TABLE 7.16 GROUNDWATER GAUGING DATA ........................................... 65 TABLE 7.17 SURFACE WATER DISCHARGE HYDROCHEMICAL

PARAMETERS (DISCHARGE SAMPLING EVENT) ................... 68 TABLE 7.18 ON-BASE SURFACE WATER HYDROCHEMICAL

PARAMETERS (POST WET-SEASON SAMPLING EVENT) ....................................................................................... 69

TABLE 7.19 OFF-BASE SURFACE WATER HYDROCHEMICAL PARAMETERS ............................................................................ 70

TABLE 7.20 FRESH SURFACE WATER HYDROCHEMICAL PARAMETERS ............................................................................ 71

TABLE 7.21 ESTUARINE SURFACE WATER HYDROCHEMICAL PARAMETERS ............................................................................ 71

TABLE 7.22 SUMMARY OF PFAS SOIL RESULTS AT INGHAM SPORTS FIELDS ........................................................................ 72

TABLE 7.23 SUMMARY OF PFAS SOIL RESULTS IN THE VICINITY OF THE OLAS ............................................................................. 72

TABLE 7.24 SUMMARY OF PFAS SOIL RESULTS AT THE FORMER FIRE TRAINING GROUND NQ0054 ........................... 73

LIST OF TABLES (CONTINUED) TABLE 7.25 SUMMARY OF PFAS SOIL RESULTS AT THE

EASTERN BASE BOUNDARY AT GARBUTT ............................ 73 TABLE 7.26 SUMMARY OF PFAS SOIL RESULTS IN

RESIDENTIAL PROPERTY SOILS ............................................. 74 TABLE 7.27 SUMMARY OF PFAS GROUNDWATER RESULTS AT

FIRE TRAINING GROUND NQ0105 ........................................... 75 TABLE 7.28 SUMMARY OF PFAS GROUNDWATER RESULTS AT

FIRE TRAINING GROUND NQ0106 AND THE OLAS ................ 75 TABLE 7.29 SUMMARY OF PFAS GROUNDWATER RESULTS AT

PAD BRAHMAN AND THE NORTH-WESTERN BASE BOUNDARY ................................................................................ 76

TABLE 7.30 SUMMARY OF PFAS GROUNDWATER RESULTS AT RUNWAY 13/31 AND WESTERN BASE BOUNDARY ............... 76

TABLE 7.31 SUMMARY OF PFAS GROUNDWATER RESULTS AT MOUNT ST JOHN ....................................................................... 76

TABLE 7.32 SUMMARY OF PFAS GROUNDWATER RESULTS AT FUEL FARM 2 NQ0099 ............................................................... 77

TABLE 7.33 SUMMARY OF PFAS GROUNDWATER RESULTS AT FIRE STATION NQ0055, FIRE TRAINING GROUND NQ0107 AND SURROUNDS....................................................... 77

TABLE 7.34 SUMMARY OF PFAS GROUNDWATER RESULTS AT 5 AVN .......................................................................................... 78

TABLE 7.35 SUMMARY OF PFAS GROUNDWATER RESULTS AT 38 SQN AND THE DOMESTIC AREA ........................................ 78

TABLE 7.36 SUMMARY OF PFAS GROUNDWATER RESULTS AT FIRE TRAINING GROUND NQ0054 AND FUEL FARM 1 NQ0052 ......................................................................... 79

TABLE 7.37 SUMMARY OF PFAS GROUNDWATER RESULTS AT INGHAM ROAD SPORTS FIELDS .............................................. 79

TABLE 7.38 SUMMARY OF PFAS GROUNDWATER RESULTS AT THE TOWN COMMON ................................................................ 79

TABLE 7.39 SUMMARY OF PFAS GROUNDWATER RESULTS AT PALLARENDA AND CLEVELAND BAY ...................................... 80

TABLE 7.40 SUMMARY OF PFAS GROUNDWATER RESULTS AT FORMER ROWES BAY LANDFILL ............................................. 80

TABLE 7.41 SUMMARY OF PFAS GROUNDWATER RESULTS AT ROWES BAY ............................................................................... 80

TABLE 7.42 SUMMARY OF PFAS GROUNDWATER RESULTS AT BELGIAN GARDENS .................................................................. 81

TABLE 7.43 SUMMARY OF PFAS GROUNDWATER RESULTS AT GARBUTT ................................................................................... 81

TABLE 7.44 SUMMARY OF PFAS GROUNDWATER RESULTS AT BUSHLAND BEACH, MOUNT ST JOHN AND BOHLE ............... 82

LIST OF TABLES (CONTINUED) TABLE 7.45 SUMMARY OF PFAS GROUNDWATER RESULTS IN

RESIDENTIAL PROPERTY EXTRACTION BORES ................... 82 TABLE 7.46 SUMMARY OF PFAS GROUNDWATER RESULTS IN

COMMERCIAL PROPERTY EXTRACTION BORES .................. 83 TABLE 7.47 SUMMARY OF GROUNDWATER GEOCHEMISTRY, IA ........... 84 TABLE 7.48 SUMMARY OF PFAS DISCHARGE SURFACE WATER

RESULTS .................................................................................... 87 TABLE 7.49 SUMMARY OF PFAS ON-BASE SURFACE WATER

RESULTS .................................................................................... 88 TABLE 7.50 SUMMARY OF PFAS OFF-BASE UPGRADIENT

(GARBUTT) SURFACE WATER RESULTS................................ 89 TABLE 7.51 SUMMARY OF PFAS OFF-BASE DOWNGRADIENT

MUNDY CREEK CATCHMENT SURFACE WATER RESULTS .................................................................................... 90

TABLE 7.52 SUMMARY OF PFAS OFF-BASE DOWNGRADIENT THREE MILE CREEK CATCHMENT SURFACE WATER RESULTS ...................................................................... 90

TABLE 7.53 SUMMARY OF PFAS OFF-BASE DOWNGRADIENT TOWN COMMON SURFACE WATER RESULTS ...................... 90

TABLE 7.54 SUMMARY OF PFAS OFF-BASE BACKGROUND AND DOWNGRADIENT BOHLE RIVER SURFACE WATER RESULTS .................................................................................... 91

TABLE 7.55 SUMMARY OF PFAS OFF-BASE BACKGROUND SURFACE WATER RESULTS .................................................... 91

TABLE 7.56 SUMMARY OF SURFACE WATER MAJOR ION CHEMISTRY ............................................................................... 91

TABLE 7.57 SUMMARY OF PFAS ON-BASE SEDIMENT RESULTS ............ 93 TABLE 7.58 SUMMARY OF PFAS OFF-BASE UP-GRADIENT

(GARBUTT) SEDIMENT RESULTS ............................................ 93 TABLE 7.59 SUMMARY OF PFAS OFF-BASE DOWNGRADIENT

MUNDY CREEK CATCHMENT SEDIMENT RESULTS .............. 93 TABLE 7.60 SUMMARY OF PFAS OFF-BASE DOWNGRADIENT

THREE MILE CREEK CATCHMENT SEDIMENT RESULTS .................................................................................... 93

TABLE 7.61 SUMMARY OF PFAS OFF-BASE DOWNGRADIENT TOWN COMMON SEDIMENT RESULTS ................................... 94

TABLE 7.62 SUMMARY OF PFAS OFF-BASE BACKGROUND AND DOWNGRADIENT BOHLE RIVER CATCHMENT SEDIMENT RESULTS ................................................................ 94

TABLE 7.63 SUMMARY OF PFAS OFF-BASE BACKGROUND SEDIMENT RESULTS ................................................................ 94

TABLE 8.1 SUMMARY OF ON-BASE SOIL SCREENING RESULTS .................................................................................... 99

LIST OF TABLES (CONTINUED) TABLE 8.2 SUMMARY OF ON-BASE GROUNDWATER

SCREENING RESULTS ............................................................ 104 TABLE 8.3 ON-BASE CHANGES IN CONCENTRATIONS OF

PFOS + PFHXS BETWEEN DRY AND WET PERIOD SAMPLING ................................................................................ 111

TABLE 8.4 OFF-BASE CHANGES IN CONCENTRATIONS OF PFOS + PFHXS BETWEEN DRY AND WET SEASON SAMPLING ................................................................................ 113

TABLE 8.5 PFAS SOURCE AREA SURFACE WATER DRAINAGE .......... 119 TABLE 8.6 SURFACE WATER CHANGES IN CONCENTRATIONS

OF PFOS + PFHXS BETWEEN DRY AND WET PERIOD SAMPLING ................................................................. 127

TABLE 9.1 SOURCES AND SIGNIFICANCE OF PFAS IMPACT BY IA CATCHMENT ........................................................................ 130

TABLE 9.2 CONCEPTUAL SITE MODEL FOR THE THREE MILE CREEK CATCHMENT ............................................................... 133

TABLE 9.3 CONCEPTUAL SITE MODEL FOR THE LOUISA CREEK/TOWN COMMON/BOHLE RIVER CATCHMENT ............................................................................ 134

TABLE 9.4 CONCEPTUAL SITE MODEL FOR THE MUNDY CREEK CATCHMENT ............................................................... 136

LIST OF FIGURES FIGURE 2.1 FLOOD OVERLAY OF IA (TOWNSVILLE CITY PLAN

2017) ........................................................................................... 19 FIGURE 2.2 FISH HABITAT AREAS (NPRSR 2012) ...................................... 21 FIGURE 2.3 AQUATIC ECOLOGICAL CONSERVATION

ASSESSMENT MAP (ROLLASON AND HOWELL 2017) ........... 21 FIGURE 2.4 REGULATED VEGETATION MANAGEMENT MAP

(RVM CATEGORY C – HIGH VALUE REGROWTH VEGETATION IS NOT PRESENT IN THE FIGURE) .................. 22

FIGURE 7.1 PIPER DIAGRAM FOR ON-BASE WELLS ................................. 85 FIGURE 7.2 PIPER DIAGRAM FOR OFF-BASE WELLS................................ 86 FIGURE 8.1 RELATIONSHIP OF CHANGES GROUNDWATER

PFOS+PFHXS CONCENTRATIONS AND GROUNDWATER LEVELS BETWEEN AUGUST 2017 AND APRIL 2018 ....................................................................... 117

FIGURE 8.2 PFOS + PFHXS IN SOIL AND GROUNDWATER ..................... 118 FIGURE 8.3 APRIL 2018 – PFOS + PFHXS IN SURFACE WATER

AND SEDIMENT ....................................................................... 120 FIGURE 8.4 DISCHARGE SAMPLING PFOS+PFHXS AND EC................... 122

VOLUME 2 LIST OF APPENDICES APPENDIX A FIGURES

APPENDIX B TABLES

APPENDIX C DATA VALIDATION

APPENDIX D SITE PHOTOGRAPHS

APPENDIX E LABORATORY DOCUMENTATION

Project No PS102571 RAAF Base Townsville - Seasonal Monitoring Report 1 - PFAS Volume 1: Main Report Department of Defence

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GLOSSARY TERM DEFINITION

Adsorption The attachment of molecules of a solute in a liquid as a thin film on the outside surface or internal surfaces of a solid material (especially soil or organic material).

Aquifer A geologic formation capable of conducting and transmitting water.

Biodegradation The process by which organic substances are decomposed by micro-organisms into simpler substances such as water, carbon dioxide and ammonia.

Catchment The area from which a surface watercourse or a groundwater system derives its water.

Conceptual Site Model A representation of site-related information regarding contamination sources, receptors and exposure pathways between those sources and receptors.

Desorption The process in which atomic or molecular species leave the surface of a solid into a surrounding solute; the reverse of adsorption.

Diffuse source A source of PFAS with no specific point of discharge.

Hydrogeology The study of subsurface water in its geological context.

Hydrolysis The chemical breakdown of a compound due to reaction with water.

Hydrophobic Tending to repel or fail to mix with water.

Impact Influence or effect exerted by a substance or activity on the natural, built and community environment.

Investigation Area RAAF Base Townsville and surrounding areas defined on Figure 1, Appendix A.

Legacy Firefighting Foam

Firefighting foam which contained PFAS such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) as active ingredients and often contained other PFAS such as perfluorohexane sulfonate (PFHxS) as an impurity in the manufacturing process. In 2004, Defence commenced phasing out its use of legacy firefighting foam containing PFOS and PFOA as active ingredients and transitioned to a more environmentally safe product called Ansulite for use on the Defence estate.

Lipophilic Tending to combine with or dissolve in lipids, fats and oils.

Pathway The mechanism by which PFAS may reach and be exposed to a given receptor.

Photolysis The decomposition or separation of molecules by the action of light.

Point Source Single identifiable source of potential PFAS impact (e.g. storage tank).

Precursor A substance from which PFOS and PFOA may be formed through (bio)chemical reactions.

Receptor A person, animal, plant, ecosystem, property or controlled water body that may be detrimentally affected by exposure to PFAS.

Risk assessment A systematic process of evaluating the potential risk that may be posed by a hazardous substance (PFAS in the context of this DSI) to a receptor.

Soluble Susceptible to being dissolved in a liquid, especially water.


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TERM DEFINITION

Source A potentially hazardous substance that may be released to the environment (PFAS in the context of this DSI).

Standing water level The surface of saturation in a shallow aquifer at which the pressure of the water is equal to that of the atmosphere (also known as water table).

Volatility Tendency of a substance to evaporate at normal temperatures.


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ABBREVIATIONS 5 AVN 5th Aviation Regiment

38 SQN 38 Squadron

AEP annual exceedance probability

AFFF aqueous film forming foam

ALS Australian Laboratory Services

ANZECC Australian and New Zealand Environment Conservation Council

ARMCANZ Agriculture and Resources Management Council of Australia and New Zealand

AS Australian Standard

BOD biological oxygen demand

BOM Bureau of Meteorology

COC chain of custody

COD chemical oxygen demand

COPC contaminants of potential concern

CP Crown Plan

CSM Conceptual Site Model

DES Department of Environment and Science, Queensland

DNPSR Department of National Parks, Sports and Racing, Queensland

DNRM Department of Natural Resources and Mines, Queensland

DoEE Department of Environment and Energy (Commonwealth of Australia)

DOH Department of Health, Queensland

DOD Department of Defence (Commonwealth of Australia)

DQI data quality indicator

DQO data quality objective

DSI Detailed Site Investigation

EC electrical conductivity

ECC Environmental Clearance Certificate

EHP (Department of) Environment and Heritage Protection (now DES), Queensland

EMP Environmental Management Plan

ERA Ecological Risk Assessment

FSANZ Food Standards Australia and New Zealand

GME groundwater monitoring event

GPS global positioning system


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GSE Ground Support Equipment

ha hectare

HBGV Health-Based Guidance Value

HDPE high-density polyethylene

HEPA Head of Environmental Protection Authorities

HESP Health Environment and Safety Plan

HHRA Human Health Risk Assessment

IA Investigation Area

ILs Investigation Levels

K hydraulic conductivity

L/sec Litres per second

LGA Local Government Area

LOR limit of reporting

mAHD metres Australian Height Datum

mBGL metres below grade level

mBTOC metres below top of casing

m/day metres per day

MGA Map Grid of Australia

mg/kg milligrams per kilogram

mg/L milligrams per litre

MSES matter of State environmental significance

mV millivolts

NAPL non-aqueous phase liquids

NATA National Association of Testing Authorities

NEPC National Environment Protection Council

NHMRC National Health and Medical Research Council

NRMMC National Resource Management Ministerial Council

NUDLC National Uniform Drillers Licencing Committee

OEH Office of Environment and Heritage

OLA ordnance loading apron

OMP Ongoing Monitoring Plan

QA quality assurance

QC quality control

PFAA perfluoroalkyl acids


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PFAS per- and poly-Fluoroalkyl Substances

PFAS NEMP PFAS National Environmental Management Plan

PFCA perfluoroalkane carboxylic acids

PFHxS perfluoro-n-hexane sulfonic acid

PFOA perfluoro-n-octanoic acid

PFOS perfluoro-n-octane sulfonic acid

PFSA perfluoroalkane sulfonic acids

PMAP PFAS Management Area Plan

PSD particle size distribution

RAAF Royal Australian Air Force

RAAF TVL Royal Australian Air Force Base Townsville

RP Registered Plan

RPD relative percent difference

RWL relative water level

SAQP Sampling, Analysis and Quality Plan

SQP Suitably Qualified Person

SP Survey Plan

SPP State Planning Policy

SWL Standing Water Level

TA Technical Advisor

TAPL Townsville Airport Proprietary Limited

TCC Townsville City Council

TDS total dissolved solids

TOC total organic carbon

TOP total oxidisable precursor

TSS total suspended solids

USCS Unified Soil Classification System

US EPA United States Environmental Protection Agency

WQ water quality

WSP WSP Australia Pty Ltd

WTP water treatment plant

µg/L micrograms per litre

µS/cm microsiemens per centimetre


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EXECUTIVE SUMMARY

BACKGROUND WSP (May 2018) completed a Detailed Site Investigation (DSI) for the assessment of per- and poly-fluoroalkyl substances (PFAS) at the Royal Australian Air Force (RAAF) Base Townsville (RAAF TVL) (the ‘Base’) and surrounding areas. The purpose of the investigations was to, where reasonably practical, quantify potential risk to human health and the environment associated with the use of legacy aqueous film forming foam (AFFF) at the Base. These legacy firefighting foams contained PFAS as active ingredients.

Additional wet season groundwater, soil, surface water and sediment investigations were undertaken as an extension to the DSI to close DSI data gaps and to provide further information about the nature and distribution of PFAS on-Base and off-Base during periods of increased rainfall. The additional investigations targeted the Base and surrounding off-Base areas, including the Townsville Town Common Conservation Park (the Town Common) and the suburbs of Garbutt, Rose Bay, Belgian Gardens and Pallarenda (the ‘Investigation Area’ (IA)).

This report presents the findings of the Seasonal Monitoring Report 1 for the assessment of PFAS at RAAF TVL and surrounding areas.

OBJECTIVES The primary objective of the DSI was to understand potential human health and environmental risks both on the Base and to the surrounding area, resulting from legacy AFFF usage at the Base.

The key objectives of the DSI component of the project were to:

— improve the understanding of the historical and current use of AFFF at the Base and other potential point and diffuse sources of PFAS within the IA

— improve the understanding of the distribution and nature of PFAS impact in soil, sediments, groundwater and surface water at the Base

— assess the nature and extent of PFAS distribution (if any) in soil, groundwater, surface water, sediments and biota at the location of potential receptors (i.e. within IA)

— define the conceptual site model (CSM) to describe PFAS sources, pathways and potentially exposed human and environmental receptors within IA

— generate input data for the development of the Human Health Risk Assessment (HHRA) and Environmental Risk Assessment (ERA); and

— generate input data for the development of the PFAS Management Area Plan (PMAP) for PFAS management within the Base.

The objectives of the wet season investigation were to supplement the DSI data with specific information regarding PFAS behaviour in the IA during and after the wet season. A number of data gaps in the DSI soil investigation were also filled through near-surface soil sampling at selected locations.

The Seasonal Monitoring Report 1 is the fourth major deliverable for the project and will inform next stages of work, ultimately contributing to the overarching project objectives being met.


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SCOPE OF WORKS The scope of works for the Seasonal Monitoring Report 1 investigation was developed and conducted with reference to the National Environment Protection Council (NEPC) (2013) National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1). The works comprised:

— surface water discharge sampling following a significant rainfall event in March 2018 — a post-wet season sampling event comprising groundwater, surface water and sediment sampling, conducted in April

2018 — collection of soil samples on-Base to fill data gaps from the DSI — collection of soil, groundwater, swimming pool and fruit and vegetable samples from selected residences in the IA to

inform the HHRA (WSP 2018a) — analysis of soil, sediment, groundwater and surface water samples for PFAS, including quality assurance (QA) and

quality control (QC) analysis (intra- and inter-laboratory duplicates, equipment rinsate blanks and trip blanks) — comparison of analytical laboratory results against adopted published investigation criteria — discussion of results, including the refinement of the DSI CSM to identify relevant source – receptor pathways — identification of gaps and uncertainties with recommendations for further assessment.

FINDINGS

SITE SETTING

The Base contains and is surrounded by several features that are considered to be sensitive environmental receptors: the on-Base wetlands; the wetlands on the Town Common; Louisa, Three Mile and Mundy Creeks and associated wetlands; and the Bohle River. The residential suburb of Garbutt is adjacent to the Base to the east. Industrial land is located to the south and west of the Base in Garbutt and Mount Louisa.

During the post-wet season sampling event (9–20 April 2018) completed for the Seasonal Monitoring Report 1, there was little to no rainfall, however, some grassed areas on the Base were saturated from the flooding experienced in March 2018. Aside from tidal flows and the Bohle River, no flowing water was observed in streams in the IA during the post-wet season groundwater sampling. Pooled water was observed in several locations off-Base.

SURFACE WATER DISCHARGE SAMPLING

During and immediately after the significant rainfall event on 1 March 2018, discharge sampling was undertaken at the Base. Flooding was observed across the Base and surrounds with significant flows observed to be discharging off-Base. Pumping of surface water from the runway surrounds into Lake Lydeamore and Three Mile Creek was active during this time. Flowing water was observed at several creeks off-Base and pooled water was observed in most surrounding low-lying areas such as parks, grassed areas and in the Town Common.

Surface water discharge sampling conducted immediately following the significant rainfall event in March 2018 returned results indicating that during periods of significant rainfall, PFAS impacted surface water and, to a lesser extent, physically transported sediments is being discharged from the Base into the Louisa Creek, Town Common, Three Mile Creek and Mundy Creek catchments at concentrations generally well in excess of the recreational Health-Based Guidance Values (HBGV).


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SOILS

Soil samples were collected at Ingham Road Sports Fields and on the eastern boundary of the Base to close soil data gaps (vertical delineation) that had been identified in the DSI (WSP 2018a). The shallow soil samples returned concentrations of PFAS compounds below the nominated (HBGV), effectively closing out the soil data gap.

Soil samples were also collected from five properties in Garbutt, Rowes Bay and Pallarenda where PFAS-impacted groundwater was reported in the DSI (WSP 2018a) and irrigation of lawns, gardens and vegetable gardens was/had reportedly been undertaken. PFOS + perfluoro-n-hexane sulfonic acid (PFHxS) in excess of the residential HBGVs and PFOS in excess of the residential ecological guidelines were recorded in eight soil samples collected on three properties. The PFAS impact is considered to be a result of long-term irrigation with PFAS impacted groundwater, although biomagnification processes in the root zones of fruit trees may be contributing to the elevated concentrations in some soil samples. These results have been utilised in the HHRA (WSP 2018b), which identified the health risk from PFAS in soil at these locations to be low and acceptable.

POST-WET SEASON GROUNDWATER, SURFACE WATER AND SEDIMENT SAMPLING

Groundwater levels across the IA were higher than the DSI (WSP 2018a) monitoring results, showing that groundwater rose in response to rainfall during the wet season. Groundwater flow directions and rates were generally the same as during the DSI investigation (WSP 2018b). The total dissolved solids (TDS) concentrations in the groundwater were lower than the DSI results (WSP 2018b) in 67% of the wells.

Groundwater sampled from all monitoring wells on the Base during the post-wet season monitoring returned above detection PFAS concentrations, indicating widespread PFAS groundwater impact beneath the Base. During the DSI (WSP 2018a) the absence of PFAS in isolated monitoring wells (MW104, MW140 and MW142) suggested that there was not one continuous PFAS ‘plume’ beneath the Base, but a series of PFAS ‘plumes’ and multiple pathways related to specific source areas and possibly surface water bodies. Groundwater samples that had previously returned concentrations below the laboratory limit of reporting (LOR) in the DSI were selected for ultra-trace PFAS analysis as part of the post-wet season monitoring event. The ultra-trace analysis has shown that PFAS appears to be ubiquitous in groundwater beneath the Base; however, isolated, elevated concentrations are associated with individual source areas.

The detection of PFAS in all off-Base monitoring wells (with the exception of monitoring wells analysed at a higher detection limit – MW202, MW204, MW205, MW207 and MW212) to the north-west, north, north-east, south-east and east of the Base suggests that groundwater ‘plumes’ have transported PFAS off-Base in these directions. However, irregularities in the results, such as the anomalously high results in MW206 and MW216, suggest that the groundwater impacts are not continuous plumes’ in the traditional hydrogeological sense i.e. a relatively homogeneous dissolved mass of chemical with steadily declining concentration away from the primary source. Elevated concentrations of PFAS in groundwater at a distance from the Base are considered more likely to be a result of surface water PFAS transport with subsequent infiltration of PFAS impacted water into the underlying aquifer. The discharge monitoring undertaken during March 2018 supports this theory, with large volumes of surface water with relatively high concentrations of PFAS observed to be draining off the Base into the surface water bodies of the Town Common and the Three Mile Creek and Mundy Creek catchments.

PFAS concentrations in the post-wet season groundwater samples were generally higher than in the DSI samples; however this trend was not consistent, with 29% of locations recording lower PFAS concentrations during the post-wet season as compared to the corresponding DSI samples. The groundwater impact to the south (up-gradient) and south-east (across-gradient) of the Base is considered likely to be the result of an unidentified off-Base source.

PFAS was detected in surface water and sediment on- and off-Base at concentrations in exceedance of the nominated guidelines during the post-wet season sampling event. It is unclear whether the PFAS impacted sediments found at a distance from the Base have been transported to those locations, or whether dissolved phase PFAS has been transported to the location and then bound to the sediments.

PFAS concentrations in surface water were generally slightly higher in the post-wet season sampling event than in the DSI, which was conducted during the 2017 dry season. Sediment PFAS concentrations did not show an obvious trend.


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Results of samples collected up-gradient of the Base indicate a potential background source of PFAS exists in the upper catchments of Louisa and Peewee creeks and in the middle reaches of the Bohle River. However, compared with the concentrations recorded in surface waters discharging from the Base, the background up-gradient input of PFAS concentrations to the IA is considered to be minor in the context of the investigation.

BIOTA (FRUIT AND VEGETABLES)

Selected sampling of fruit and vegetables was undertaken at residences who identified that they irrigated their gardens with groundwater, and whose groundwater bore samples returned positive PFAS detections during the DSI (WSP 2018a).

No PFAS was detected in any fruit sample obtained and PFOS was only detected in one sample of spinach at a concentration of 0.002 mg/kg. These results were used in the HHRA, which identified a low and acceptable health risk associated with the ingestion of home-grown fruit and vegetables in the IA.

CONCEPTUAL SITE MODEL The CSM presented in the DSI was updated on the basis of the Seasonal Monitoring Report 1 findings and has been presented in three parts, representing the three primary receiving surface water catchments in the IA (Three Mile Creek; Louisa Creek/Town Common; Mundy Creek). A summary of the linkages between identified sources, exposure pathways and sensitive receptors for the three catchments is in a graphical representation below.


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Figure ES.1 Conceptual Site Model for the Three Mile Creek catchment


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Figure ES.2 Conceptual Site Model for the Louisa Creek/Town Common/Bohle River catchment


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Figure ES.3 Conceptual Site Model for the Mundy Creek catchment


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The CSMs were refined by comparing sample concentrations against the relevant ‘Tier 1’ screening criteria (ILs) developed consistent with National Environment Protection Council (NEPC) (2013) National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1), which is considered to be protective of the specific receptor/pathway combination. Where PFAS concentrations were detected below the relevant screening criteria, the exposure pathway was considered to be incomplete.

Where a potentially complete exposure pathway from source to receptor is identified, the next step is to undertake a risk assessment to evaluate the potential for adverse health or ecological effects. The potentially complete pathways identified above are addressed in the separate HHRA (WSP 2018b) and ERA (WSP 2019a) inclusive of results presented in this Seasonal Monitoring Report 1.

CONCLUSIONS PFAS impact has been identified in surface water, sediment and groundwater off-Base.

Based on the findings of the DSI (WSP 2018) and this Seasonal Monitoring Report 1, the following additional works have been triggered and have been completed:

— a HHRA (WSP 2018b) has been completed and published on the Defence website (http://www.defence.gov.au/Environment/PFAS/docs/Townsville/Reports/HumanHealthRiskAssessmentReportBody.pdf). The HHRA assesses potential risk to human health associated with the potentially complete source-pathway-receptor exposure linkages identified in the CSM

— an ERA (WSP 2019a) has been completed to assess potential risk associated with the potentially complete ecological source-pathway-receptor exposure linkages identified in the CSMs; and

— a PMAP (WSP 2019b) has been completed to provide management plans to mitigate the potential impact to human health and the environment from identified PFAS in the IA and to mitigate the potential migration of PFAS off-Base.


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1 INTRODUCTION

1.1 PREAMBLE WSP Australia Pty Ltd (WSP) was engaged by the Department of Defence (Defence) to undertake a Detailed Site Investigation (DSI) at the Royal Australian Air Force (RAAF) Base Townsville (RAAF TVL), herein referred to as the ‘Base’, located on Ingham Road, Garbutt, Queensland. The DSI included investigation of the Base and surrounding off-Base areas, including the Townsville Town Common Conservation Park (the Town Common) and the suburbs of Garbutt, Rose Bay, Belgian Gardens and Pallarenda (‘the Investigation Area’ (IA)). The IA is presented on Figure 1, Appendix A.

The DSI was based on the Sampling, Analysis and Quality Plan (SAQP), developed by WSP (WSP, 2017) and the DSI report (WSP 2018a) was presented to Defence in May 2018.

The purpose of the investigation was to, where reasonably practical, quantify potential risk to human health and the environment associated with the use of legacy aqueous film forming foam (AFFF). These legacy firefighting foams contained per- and poly-fluoroalkyl substances (PFAS) as active ingredients.

This Seasonal Monitoring Report 1 is a progression of the DSI and includes findings from a wet season groundwater monitoring event (GME), surface water and sediment investigation, plus additional targeted sampling of surface soil across the IA and various media on residential properties.

A Queensland Department of Environment and Science (DES) accredited auditor, Phil Sinclair of Coffey, was engaged by Defence as the technical advisor (TA) and third party reviewer of technical deliverables for the project, including this Seasonal Monitoring Report 1.

1.2 BACKGROUND Defence has commenced a national program to review its estate and investigate and implement a comprehensive approach to manage the impacts of PFAS on, and in the vicinity of, some of its bases around Australia. The Base was identified as one with known historical and current AFFF use.

AFFF is the primary product stored and used by Defence at the Base for fire-fighting purposes, including routine testing and in emergency fire-fighting response practice drills.

Older formulations of firefighting foam used at the base included perfluoro-n-octane sulfonic acid (PFOS) and perfluoro-n-octanoic acid (PFOA) as active ingredients. Firefighting foams containing PFAS were used extensively worldwide and within Australia by both civilian and military authorities due to their effectiveness in extinguishing liquid fuel fires.

In 2003, Defence became aware that PFOS was an emerging contaminant and in 2004, Defence commenced phasing out its use of legacy firefighting foam containing PFOS and PFOA as active ingredients and transitioned to a more environmentally safe AFFF product called Ansulite for use on the Defence estate.

The Base is a joint military and civilian airfield, with adjacent/nearby residential communities of Garbutt, Rowes Bay, Belgian Gardens and Pallarenda. The Base is also adjacent to the Town Common, a wetland listed on the Commonwealth estate that is used by migratory birds and is a barramundi breeding area.

Broadly, the Project has been defined to consist of the following phases:

— Phase 1: DSI – Published 9 May 2018 (WSP 2018a) and supported by this Seasonal Monitoring Report 1 — Phase 2A: Human Health Risk Assessment (HHRA) – Published 31 October 2018 (WSP 2018b) — Phase 2B: Ecological Risk Assessment (ERA) – under development; and — Phase 3: PFAS Management Area Plan (PMAP) – under development.


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The HHRA was issued as a separate report, but incorporated the findings of the DSI and this Seasonal Monitoring Report 1. The ERA and PMAP are to be issued as separate reports, incorporating the findings of the DSI and Seasonal Monitoring Report 1.

This Seasonal Monitoring Report 1 presents the results of the additional wet season sampling and should be read in conjunction with the DSI Report (WSP 2018a) and the HHRA (WSP 2018b).

1.3 OBJECTIVE

1.3.1 PROGRAM STRATEGIC AIM

The strategic aim of the (Defence) National (PFAS) Plan is to manage potential risk to human health, or the ecological environment posed by the legacy PFAS impact from the Defence estate.

1.3.2 PROJECT KEY OBJECTIVES

Defence’s primary project objective was to understand potential human health and environmental risks both on the Base and to the surrounding areas, resulting from legacy AFFF usage at the Base.

The key objectives of the DSI component of the project were to:

— improve the understanding of the historical and current use of AFFF at the Base and other potential point and diffuse sources of PFAS within the IA

— improve the understanding of the distribution and nature of PFAS impact in soil, sediments, groundwater and surface water at the Base

— assess the nature and extent of PFAS distribution (if any) in soil, groundwater, surface water, and sediments at the location of potential receptors (i.e. within IA)

— define the conceptual site model (CSM) to describe PFAS sources, pathways and potentially exposed human and environmental receptors within IA

— generate input data for the development of the HHRA and ERA; and — generate input data for the development of the PMAP for PFAS management within the Base.

The objectives of the Seasonal Monitoring Report 1 were to supplement the DSI data with specific information regarding PFAS behaviour in the IA during and after the wet season. A number of data gaps in the DSI soil investigation were also filled through near-surface soil sampling at selected locations.

In addition to Defence technical guidelines, the DSI design was developed with reference to the National Environment Protection Council (NEPC) (2013) National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1). Some aspects of the DSI varied from industry-standard approach, including seeking to obtain data on potential impacts to both on- and off-Base receptors as early in the program as practicable, rather than following traditional methods of progressively stepping-out from known or suspected sources towards receptors. These approaches remain technically robust but were undertaken to accelerate end point achievement for Defence, rather than the traditional approach of staging time and cost. In addition, historical titles for the Base were not interrogated, as the land is known to have been used as an Air Force Base since World War II, years before the advent of PFAS-containing AFFF, and the historical titles would not have added to the knowledge of AFFF use at the Base and the IA.

1.4 CONTEXT OF THE DSI Numerous previous investigations have been undertaken at the Base, investigating the nature and distribution of a broad suite of contaminants including PFAS in soils, groundwater and sediments (Section 3.1). A review of the available documentation was undertaken by WSP and the DSI scope of works was developed in order to fill knowledge gaps at the Base (source areas, geographical, media and analytical) and predict likely off-Base migration pathways and potential receptors of PFAS impact.


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The works undertaken by WSP since engagement (in 2017) to date has included:

— Seasonal Monitoring Report 1 (this report): supplementary Phase 2 wet season investigations into PFAS concentrations in on-Base and off-Base groundwater, surface water and sediment.

— DSI (WSP 2018a): Phase 1 investigations including historical reviews, interviews with former users of AFFF, environmental setting of Base and surrounding area; and Phase 2 investigations into PFAS concentrations in on-Base and off-Base soil, groundwater and sediment, off-Base residential water bores and detailed hydrogeological investigations. It is noted that off-Base biota sampling has not been presented or discussed in detail in this report, rather they are discussed in the HHRA and ERA (refer below).

— HHRA (WSP 2018b): multiple pathway HHRA to evaluate the potential human health risks from PFAS impact to identified potential receptors in the IA. This report included consideration of direct exposures to environmental media (e.g. soil, groundwater, surface water and sediment) and secondary exposures via dietary intake, such as the consumption of seafood sourced from within the IA.

— ERA (WSP 2019a): multiple pathway ERA to evaluate the potential risk from PFAS impact to identified ecological receptors in the IA. The ERA will also consider the potential for wider ecosystem impacts from the accumulation of PFAS in aquatic and terrestrial organisms exposed to PFAS impacted media.

— Community Engagement: support Defence with the facilitation of community engagement and communication as related to the DSI, HHRA and ERA, including water use surveys; newsletters, advertising, a webpage and hotline; and community information events.

— PMAP (WSP 2019c): development of management plans to mitigate the potential impact to human health and the environment from identified PFAS in the IA and to mitigate the potential migration of PFAS off-Base.

1.5 SCOPE OF WORKS

1.5.1 DSI

The scope of works completed to develop the DSI are detailed in WSP (2018a) and included:

— desktop investigation — site inspection — PFAS historical study — on-Base groundwater, surface water and sediment sampling — off-Base groundwater, surface water and sediment sampling — residential bore sampling — commercial bore sampling; and — biota sampling.

The supplementary scope of works completed following the wet season and reported in this Seasonal Monitoring Report 1 are detailed in Section 1.5.2.

1.5.2 SEASONAL MONITORING REPORT 1

ON-BASE SOIL, GROUNDWATER, SURFACE WATER AND SEDIMENT SAMPLING

— Liaison with Defence for airside access.

— Collection and PFAS analysis of discharge surface water samples from four Base perimeter locations, generally twice a day, for five days immediately following the rainfall event of 1 and 2 March 2018 (Section 7.7).

— Collection and PFAS analysis of ten surface soil samples to assist with closing a data gap from the DSI (Section 7.5.1).


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— Collection of 91 groundwater samples from 69 monitoring wells to provide ‘post-wet season’ data; samples from 23 wells were split with one fraction unfiltered and the other fraction filtered, with both fractions analysed for PFAS. The wells were sampled using Hydrasleeves™ (Section 7.6.1).

— Collection and PFAS analysis of 32 surface water samples from 22 locations in existing drains and open channels to provide ‘wet season’ data; samples from 10 locations were split with one fraction unfiltered and the other fraction filtered, with both fractions analysed for PFAS (Section 0).

— Collection and PFAS analysis of 26 sediment samples from existing drains and open channels from selected locations to provide ‘wet season’ data (Section 7.8.1).

OFF-BASE SOIL, GROUNDWATER, SURFACE WATER, SEDIMENT SAMPLING

— Liaison with Townsville City Council (TCC), Townsville Airport Proprietary Limited (TAPL) and Queensland Department of National Parks, Sports and Racing (DNPSR) for permitting and access.

— Collection and analysis of groundwater samples from 54 monitoring wells using Hydrasleeves™ to provide ‘post-wet season’ data (Section 7.6.2).

— Collection and analysis of 32 surface water samples from creeks and channels to provide ‘post-wet season’ data (Section 7.7.2.2).

— Collection and analysis of 31 sediment samples from targeted locations in existing drains, open channels, creeks and estuaries to provide ‘wet season’ data (Section 7.8.2).

RESIDENTIAL SAMPLING

Residents with known bores were contacted with an offer to collect a post-wet season sample from their bores. 26 bores were sampled and analysed for PFAS.

— Water from operational bores (18) was sampled from the ‘first flush’ from a tap connected to the bore. Non-operational bores (four) were sampled by grab sample from the screened section of the bore using a Hydrasleeve™ (Section 7.6.3).

Additional water, soil and biota sampling was undertaken from selected residences to inform the HHRA (WSP 2018b).

— collection and PFAS analysis of one pool water sample from one residence — collection and PFAS analysis of 31 surface soil samples from seven residences — collection and PFAS analysis of seven biota (fruit and vegetables) samples from three residences.

COMMERCIAL BORE SAMPLING

Commercial residents with known or assumed bores were contacted with an offer to collect a post-wet season sample from their bores; 15 bores were sampled and analysed for PFAS. Several bores were inaccessible due to flooding.

— Water from operational bores (one) was sampled from the ‘first flush’ from a tap connected to the bore. Monitoring and non-operational bores (14) were sampled by grab sample from the screened section of the bore using a Hydrasleeve™ (Section 7.6.4).

1.5.3 ANALYTICAL SUITE Laboratory analysis of all samples was undertaken for the key contaminant of potential concern (COPC), namely 28 PFAS compounds. The minimum required suite of PFAS compounds for analysis was provided by Golder Associates (Golder 2017) and Department of Defence Guidance Document E (DoD 2018) and included:

— Perfluorobutanoic acid (PFBA) — Perfluoro pentanoic acid (PFPA or PFPeA) — Perfluoro-n-hexanoic acid (PFHxA) — Perfluoro-n-heptanoic acid (PFHpA) — Perfluoro-n-octanoic acid (PFOA)


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— Perfluoro-n-nonanoic acid (PFNA) — Perfluoro-n-decanoic acid (PFDA) — Perfluoro-n-undecanoic acid (PFUnDA) — Perfluoro-n-dodecanoic acid (PFDoDA) — Perfluoro-n-tridecanoic acid (PFTriDA) — Perfluoro-n-tetradecanoic acid (PFTeDA) — Perfluorobutane sulfonic acid (PFBS) — Perfluoro-n-pentane sulfonic acid (PFPeS) — Perfluoro-n-hexane sulfonic acid (PFHxS) — Perfluoro-n-heptane sulfonic acid (PFHpS) — Perfluoro-n-octane sulfonic acid (PFOS) — Perfluoro-n-decane sulfonic acid (PFDS) — Perfluorooctane sulphonamide (PFOSA) — N-Methylperfluoro-1-octane sulphonamide (N-MeFOSA) — N-Ethylperfluoro-1-octane sulphonamide (N-EtFOSA) — 2-(N-Methylperfluoro-1-octane sulphonamide)-ethanol (N-MeFOSE) — 2-(N-Ethylperfluoro-1-octane sulphonamide)-ethanol (N-EtFOSE) — N-Methyl perfluorooctane sulphonamidoacetic acid (MeFOSAA) — N-Ethyl perfluorooctane sulphonamidoacetic acid (EtFOSAA) — 4:2 Fluorotelomer sulfonic acid (4:2 FTS) — 6:2 Fluorotelomer sulfonic acid (6:2 FTS) — 8:2 Fluorotelomer sulfonic acid (8:2 FTS); and — 10:2 Fluorotelomer sulfonic (10:2 FTS).

In addition, approximately 1 in 20 samples (soils and sediment) were selected and analysed for total oxidisable precursor (TOP) assay, to provide an indication of the potential future concentration (if any) of PFAS compounds in the samples not captured by analysis of the 28-compound analytical suite above.

Samples were selected for either standard trace or ultra-trace PFAS analysis (groundwater and surface water) or standard or super-trace PFAS analysis (soil and sediment). Ultra-trace PFAS analysis was selected on samples from locations that previously (WSP 2018a) returned results below the laboratory limit of reporting (LOR), or a concentration lower than twice the standard LOR (0.10 µg/L in groundwater, 0.20 µg/L in surface water and 10 µg/kg in sediment).

Selected split samples were filtered in the laboratory before analysis of the PFAS 28-suite to provide an understanding of the concentrations of dissolved and total PFAS in the groundwater and surface water.

In addition, a selection of samples were analysed for turbidity, total suspended solids (TSS), major/minor cations and anions, ferrous iron, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) to provide groundwater chemical information that may be used to inform future remediation programs.

A selection of sediment samples were analysed for pH, electrical conductivity (EC), total organic carbon (TOC) and clay content to provide soil geochemistry information that may inform future remediation programs. Particle size distribution (PSD) analysis was also conducted on samples that had sufficient material, to assist in the confirmation of field sediment texture observations and to assist in determining the origin of the sediments.

DATA QUALITY OBJECTIVES

Systematic planning is critical to successful implementation of an environmental assessment (in this instance, the DSI and Seasonal Monitoring Report 1) and is used to define the type, quantity and quality of data needed to inform decisions. The United States Environmental Protection Agency (US EPA) has defined a process for establishing data quality objectives (DQOs) in Guidance on Systematic Planning Using the Data Quality Objectives Process (EPA QA/G-4: EPA/240/B-06/001), (US EPA, 2006), which has been referenced in the Australian NEPC (2013).


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DQOs ensure that:

— the study objectives are set — appropriate type of data is collected (based on contemporary land use and chemicals of concern); and — the tolerance levels are set for potential decision making errors.

The DQO process is a seven-step iterative planning approach. The outputs of the DQO process are qualitative and quantitative statements which are developed in the first six steps. They define the purpose of the data collection effort, clarify what the data should represent to satisfy this purpose and specify the performance requirements for the quality of information to be obtained from the data. The output from the first six steps is then used in the seventh step to develop the data collection design that meets all performance criteria and other design requirements and constraints. The DQO process adopted for the assessment program across the IA is outlined in Table 1.1.

Table 1.1 DQO process

STEP DESCRIPTION OUTCOMES

1 State the problem The purpose of the assessment was to quantify contaminant concentrations in on-Base and off-Base media (soil, sediment, surface water, groundwater and biota) and potential seasonal (rainfall) variation (sediment, surface water and groundwater) to assist in:

— quantifying the potential risk to on-Base and off-Base receptors associated with legacy AFFF use at the Base; and

— allowing determination of pragmatic and technically defensible management options, including remediation options, for the Base to assist in reducing potential risk(s) to receptors (beyond the scope of the current project).

2 Identify the decisions/goal of the investigation

The decisions to be made based on the results of the investigation are as follows:

— Have all potential source areas, media, exposure pathways and receptors been defined? — Has the contaminant plume been adequately delineated? — Has the media been adequately sampled? — Has surface water flux from the Base been adequately measured? — Were all the contaminants of concern analysed? — Can the potential risk to a receptor(s) be determined or is additional investigation

required? — Is there sufficient data to expand the SAQP for the additional assessment?

3 Identify the inputs to the decision

The inputs required to make the above decisions are as follows:

— base and regional history assessment — physical setting — IA inspection and PFAS historical review — behaviour of contaminants of concern in the environment — concentrations of COPC in media — assessment criteria (outlined in Section 6) — observation data including presence of ‘foaming’, field water quality parameters and

presence of other contaminants (e.g. hydrocarbon) — distribution, extent and severity of identified contamination; and — trends of contaminant concentrations, where applicable.

4 Define the study boundaries/ constraints on data

The boundaries of the investigation have been identified as follows:

— Spatial boundaries: the spatial boundary of the IA is defined as the extent shown on Figure 1, Appendix A, and the depth of the investigation point. The boundary was established on the basis of the Desktop Investigation, Site Inspection, PFAS Historical Study and iterative, delineation sampling during the DSI.

— Temporal boundaries: the date of the project inception (March 2017) through to the end of DSI investigations in September 2018, with the potential for extension noted.


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STEP DESCRIPTION OUTCOMES

5 Develop a decision rule

The purpose of this step is to define the parameters of interest, specify the action levels and combine the outputs of the previous DQO steps into an ‘if…then…’ decision rule that defines the conditions that would cause the decision maker to choose alternative actions.

The parameter of interest is the concentrations of PFAS COPC in media. If there is exceedance of a PFAS investigation level (IL), the location of the sample point is to be assessed to determine if there is delineation towards the receptors, and if not, then additional investigation(s) may be recommended to quantify risk.

If the PFAS COPC is below the IL and/or the source has been delineated towards the receptor, then no additional action may be necessary other than perhaps routine monitoring (e.g. groundwater monitoring event).

All recommendations will be grounded in the CSM and an informed judgement of practicality and benefit.

6 Specify limits on decision errors

The acceptable limits on decision errors to be applied in the investigation and the manner of addressing possible decision errors have been developed based on the data quality indicators (DQIs) of precision, accuracy, representativeness, comparability and completeness and are presented in Appendix C.

7 Optimise the design for obtaining data

The purpose of this step is to identify a resource-effective data collection design for generating data that satisfies the DQOs.

This Seasonal Monitoring Report 1 assessment has been designed considering the information and data obtained from the Desktop Investigation, Site Inspection, PFAS Historical Study and DSI. The resource effective data collection design that is expected to satisfy the DQOs is described in detail in Section 5.2 (methodology).

To ensure the design satisfies the DQOs, DQIs (for accuracy, comparability, completeness, precision and reproducibility) have been established to set acceptance limits on field methodologies and laboratory data collected.

All investigation works were undertaken under the supervision and delegation of the Lead Consultant, who is also a Suitably Qualified Person (SQP) in accordance with the Queensland Environmental Protection Act 1994 and a Contaminated Land Assessment Specialist – Certified Environmental Practitioner (Environment Institute of Australia and New Zealand).


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2 SITE IDENTIFICATION AND BACKGROUND

2.1 THE BASE The Base identification details are provided in Table 2.1. A layout of the Base is provided on Figure 2, Appendix A.

Table 2.1 Summary of general Base information

BASE ADDRESS INGHAM ROAD, GARBUTT, QUEENSLAND 4814

Legal identification (and area1) — Lot 282 on Crown Plan (CP) EP566 (3.202 hectares, (ha))

— Lot 418 on CP EP1061 (0.414 ha) — Lot 24 on CP EP2392 (1.349 ha) — Lot 23 on CP EP802462 (25.790 ha) — Lot 185 on Registered Plan (RP)

713911 (71.326 ha) — Lot 2 on RP713978 (3.286 ha) — Lot 249 on RP714146 (6.692 ha) — Lot 299 on RP716007 (2.972 ha) — Lot 314 on RP716876 (0.081 ha) — Lot 2 on RP720375 (2.023 ha) — Lot 2 on RP722429 (2.750 ha) — Lot 3 on RP722429 (2.640 ha)

— Lot 4 on RP722429 (2.483 ha) — Lot 1 on RP723988 (8.210 ha) — Lot 2 on RP723988 (2.135 ha) — Lot 3 on RP724098 (120.255 ha) — Lot 2 on RP746229 (7.898 ha) — Lot 1 on RP747057 (4.885 ha) — Lot 22 on RP748033 (401.856 ha) — Lot 1 on RP728951 (3.436 ha) — Lot 1 on RP802442 (0.068 ha) — Lot 7 on RP859800 (58.620 ha) — Lot 119 on RP907107 (5.427 ha) — Lot 100 on Survey Plan (SP) 100497

(1.700 ha)

Latitude -19.249217°S (approximate centre of Base – airport tower building)

Longitude 146.767146°E (approximate centre of Base – airport tower building)

Total Base area 738.327 ha

Current Base name RAAF Base Townsville (RAAF TVL)

Current Base use Joint use military and civilian airfield facility

Local government area (LGA) and zoning

The Base is not classified under the Townsville City Plan 2014 as it is Commonwealth land and not subject to state or local government planning instruments.

1 Areas of Lot/Plans gained from QueenslandGlobe™


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BASE ADDRESS INGHAM ROAD, GARBUTT, QUEENSLAND 4814

PFAS source areas Previous investigations (WSP 2018a) have identified the following potential PFAS source areas on-Base:

— Fire Training Areas (NQ0053, NQ0054, NQ0106, NQ0107 & Pad Brahman) — Fire Station (NQ0055) — Fuel farms (NQ0052 and NQ0099) — PFAS soil containment cell — Hangars in 5 AVN with AFFF-charged fire deluge systems — Areas where Open Day demonstrations including production of foam occurred;

and — Water treatment plant.

These source areas are detailed in Section 4 and presented on Figure 3, Appendix A. There are likely to be additional sources of PFAS on-Base such as emergency response locations and unrecorded equipment testing locations; however, it is considered that these additional sources are likely to provide a relatively small contribution of PFAS impact within the IA.

2.2 INVESTIGATION AREA The IA is not specifically defined by survey but is generally the area shown on Figure 1, Appendix A and comprises:

— the Base (RAAF TVL) as described in Section 2.1 — Townsville Airport — Townsville City Council (TCC) areas (including residential communities); and — the Ecological area, consisting of the Town Common and the Bohle River estuary and banks upstream to the Bruce

Highway Bridge (Ingham Road).

2.2.1 TOWNSVILLE AIRPORT

Townsville Airport adjoins the south-east portion of the Base and is located on John Melton Black Drive, Garbutt, Queensland. Identification details for Townsville Airport are provided in Table 2.2.

Table 2.2 Summary of general Townsville Airport information

SITE ADDRESS JOHN MELTON BLACK DRIVE, GARBUTT, QUEENSLAND 4814

Legal identification and area (QueenslandGlobe™)

— Lot 21 on RP 748033 (67.400 ha) — Lot 2 on RP748023 (7.504 ha) — Lot 7 on RP802404 (5.682 ha)

Latitude -19.25228°S (approximate centre of Townsville Airport – north-western corner of Lot 2 RP748023)

Longitude 146.77389°E (approximate centre of Townsville Airport – north-western corner of Lot 2 RP748023)

Total Base area 80.586 ha

Current site name Townsville Airport

Current site use Civilian airfield facility including terminals, maintenance and storage hangars, aircraft refuelling facilities, car parking and associated commercial businesses (couriers, Northern Australian Aerospace Centre of Excellence, cafes and bars).


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SITE ADDRESS JOHN MELTON BLACK DRIVE, GARBUTT, QUEENSLAND 4814

Local government area (LGA) and zoning

Townsville Airport is not classified under the Townsville City Plan 2014 as it is Commonwealth land and not subject to state or local government planning instruments.

PFAS source areas No confirmed potential PFAS source areas are known on Townsville Airport.

The grassed area in the northern section of Townsville Airport may have been used to clean fire-fighting equipment, including cleaning out AFFF tanks (GHD 2011).

2.2.2 TCC AREAS

The TCC Areas located in the IA include the suburbs of Mount St John, Bohle, Pallarenda and Rowes Bay, and parts of Belgian Gardens, Garbutt, West End, Mount Louisa, and Cosgrove, and has an area of approximately 2,506 ha.

The suburbs of Pallarenda, Rowes Bay, West End and Belgian Gardens are primarily residential; however, various public facilities and parklands also exist in these suburbs, including:

— Queensland Police Training Centre — Cleveland Youth Detention Centre — Belgian Gardens Cemetery — Cutharinga Park, West End — Garden Settlement Nursing Home (currently unoccupied – future land use is unknown) — Rowes Bay Golf Club — Pallarenda Surf Lifesaving Club; and — Robertson Park, Pallarenda.

The suburb of Garbutt includes the Base and Townsville Airport and is a mix of approximately 50% residential and 50% commercial/light industrial land use. Garbutt State School, Melrose Park and Harold Phillips Park are also located within the IA.

The section of Mount Louisa located within the IA is zoned commercial/light industrial land use under the Townsville City Plan 2014 (TCC 2014).

Mount St John is zoned commercial/light industrial (TCC 2014), with the exception of the Mount St John Water Treatment Plant, which is zoned “Dwelling – Townsville City Council” (TCC 2014).

The suburb of Bohle is zoned commercial/light industrial, with the exception of the Defence Facility on Everett Road, Mount St John, which is zoned “Defence Establishments – Army Rate Notice” (TCC 2014).

The section of Cosgrove located within the IA is “vacant land or reserve for park” (TCC 2014).

Surrounding land uses that present potential additional sources of PFAS contamination in the IA are introduced in the CSM, Table 4.1.

2.2.3 ECOLOGICAL AREA

The part of the IA referred to as the Ecological Area comprises:

— the Town Common, which is zoned “Public Utilities – Townsville City Council (Reserves)” and “Special Uses – National Parks” (TCC 2014)

— the Bohle River and Bohle River estuary, which is unzoned; and — the banks of the Bohle River and Bohle River Estuary, including parts of the suburbs of Bushland Beach, Mount

Low, Burdell, Bohle and Cosgrove. The zoning for this land is either “Vacant Land”, “Rural – Cattle Grazing (Breeding & Fattening)” or “Special Uses – Parks and Recreation (Reserves)” (TCC 2014).

The total area of the Ecological Area is approximately 4,460 ha.

The Town Common was historically used for the grazing of cattle; however, this practice was halted in the 1990s and all “wild” cattle were removed from the Town Common in the 2000s.


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2.3 ENVIRONMENTAL SETTING

2.3.1 TOPOGRAPHY AND PHYSIOGRAPHY

The topography of the IA is shown on Figure 4a, Appendix A, with the detail of the Base shown on Figure 4b, Appendix A. The general topography of the area is low lying associated with the Bohle River and part of the Town Common wetlands system. The IA covers a large section of Townsville and as described in Section 2.2, the IA is not specifically defined by survey, but rather split into four sections of the Base, Townsville Airport, TCC and Ecological Area.

BASE

The topography of the Base is generally flat with overall elevation of <10 metres Australian Height Datum (mAHD). According to the Queensland Globe (State of Queensland 2017), the ground elevation on the Base is roughly between 2 mAHD and 5 mAHD and has a minor decline from south-west to north-west. The Base is low lying and is subject to flooding as it is part of the Town Common wetlands system, with Louisa Creek running along the western side of the Base.

TOWNSVILLE AIRPORT

The topography of the Townsville Airport is similar to the Base topography as it shares the same runways and is located immediately adjacent to the Base. The airport is low-lying flood prone land and often experiences inundation from Louisa Creek and Peewee Creek. It has a flat topography with an overall elevation of <10 mAHD, and a slight decline from south-west to north-west. The general elevation of the airport is 3.8 mAHD to 5 mAHD.

TCC AREA

The TCC Area within the IA includes the suburbs as mentioned in Section 2.2.2.

The northern section of the TCC, including the suburb Pallarenda, has an overall elevation of 2 mAHD to 180 mAHD (given the occurrence of Many Peaks Range).

The north-eastern portion of the TCC Area includes the suburb of Rowes Bay and parts of Belgian Gardens. This area has an elevation of 3 mAHD to 35.5 mAHD with the highest point at the mid-section of Rowes Bay, north of Old Common Road. The area also has a slight rise in elevation towards the east.

The eastern section of the TCC Area includes the suburbs of Garbutt and part of the suburb of West End. The topography is generally flat, with a rise in topography to the north-east at the lower slopes of Castle Hill.

The southern area of the TCC Area includes the suburbs of Garbutt, Mount St John, and the northern portion of the suburb of Mount Louisa. The southern area has a generally flat topography of 4 mAHD to 6 mAHD in Garbutt, with a slight rise towards the south/south-west of the suburb. There is a rise in elevation to 20 mAHD in Mount St John towards the south side of the suburb. Parts of the suburb are low lying and can be subjected to flooding as Louisa Creek runs through Mount St John.

The western portion of the TCC Area includes the suburb of Bohle and the Bohle River. This suburb has a decline from east to west towards Bohle River, but has a generally flat topography with an elevation of less than 10 mAHD.

ECOLOGICAL AREA

The Ecological Area consists of the Town Common and the Bohle River estuary and banks upstream to the Bruce Highway. The topography of this area is generally flat and low lying, with an elevation of 2 mAHD to 5.7 mAHD; however, it has a significant rise in elevation towards the northern section of the Town Common and Shelly Beach. The northern section of the Ecological Area has an elevation of 10 mAHD to 213 mAHD, indicating a mountainous/hilly region across the northern section of the Town Common (Many Peaks Range).


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2.3.2 CLIMATE

The climate statistics of Townsville were obtained from the Bureau of Meteorology (BOM) (Station 032040: Townsville Aero). The climate statistics provided are an average from 1940 until 2018 (as of September 2018). A review of the climate statistics provided by BOM, indicated the following:

— The average maximum temperature annually is 28.9°C and the average minimum temperature annually is 19.8°C. The monthly mean maximum temperature occurs in December with a mean maximum temperature of 31.5°C. The monthly mean minimum temperature is 13.7°C and occurs in July.

— The annual average rainfall is 1127.9 mm, with the mean minimum rainfall occurring in September with a rainfall of 10.3 mm and a mean maximum rainfall of 296.4 mm occurring in February.

— Over a 58-year period (1957 to 2016), it was observed that the mean sunshine is 8.5 hours per day.

— Over a 61-year period (1940 to 2010 with data gaps), it was observed that the mean 9 am relative humidity annually is 66% and 3 am relative humidity is 58%. The month of February is observed to have the highest mean relative humidity annually, with 75% relative humidity at 9 am and 67% at 3 am.

2.3.3 GEOLOGY

The general underlying geology of the IA is Quaternary alluvium comprising of clay, silt, sand and gravel (DME 1997). The surface geology of the IA is presented on Figure 5, Appendix A. As the IA is split into four investigation areas, the geology of the four separate areas is described below as follows:

BASE

The geology of the Base has previously been described by several reports, including:

— SKM (2008) RAAF Base Townsville: Stage 2 Environmental Investigation — Maunsell (2005) Stage 1 Environmental Investigation, RAAF Base Townsville; and — Woodward Clyde (1999) Environmental Impact Assessment for RAAF Base Redevelopment.

Geological information was also sourced from the Townsville, Queensland, Sheet SE55-14, Australian 1:250,000 Geological Series (DME 1997). From the Townsville sheet, it is indicated that the Base has an underlying geology of Quaternary alluvium comprised of silt and clay of intertidal deposits, underlain by shelly quartz sand of beach barrier deposits; estuarine, alluvial clay, silt and sand; which are underlain by older clay, silt, sand, gravel from flood plain alluvium on high terraces.

Woodward Clyde (1999), describes that the underlying geology is underlain by basement, comprising of Permo-Carboniferous granitoids, which outcrop at Mount St John to the west and Jimmy’s Lookout to the east. This conflicts with the Townsville Geological Sheet (DME 1997), which describes the underlying basement as Julago Volcanics, comprising rhyolitic to andesitic lava, tuff, volcanic breccia, agglomerate with some conglomerate, sandstone, siltstone, shale and coal seams.

SKM (2008) explained the geology in more detail and describe that the basal sediments comprise of Pleistocene, quartzose, fluviatile sands and gravels deposited by the Ross/Bohle River Systems during the most recent glacial period approximately 15,000 BP (years before present). Furthermore, in the early Holocene (8,000 BP), deposition was dominated by shallow marine and estuarine clays, as mentioned above, and is overlain by coastal plain sediments comprising silts, clays and minor sands; sandy palaeo-channels; and the development of small strand plain of shallow sand dunes and swales along the shores of Rowes Bay (SKM 2008).

Previous investigations by Maunsell (2005) noted that the typical soil lithology is as follows:

— Sandy to clay-sand fill (0.6–1.0 m) — Grey clay with high plasticity (1.2–1.8 m), becoming brown silty clay; and — Coarse sand from the Holocene to Pleistocene fluvial sands and gravels.


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SKM (2008) added that these lithologies grade into deeper sands and gravels linked to paleo-drainages of the Ross River and Louisa Creek systems.

The sub-surface conditions encountered on-Base during the DSI (WSP 2018a) varied between locations but generally consisted of clay and silty and/or sandy clay with some layers of silty, fine to coarse grained sand. This lithology is consistent with previous investigations (SKM 2008, GHD 2011).

TOWNSVILLE AIRPORT

The underlying geology of the Townsville Airport is Quaternary alluvium comprising of clay, silt, sand and gravel; and flood plain alluvium on high terraces overlain by estuarine and alluvial clay, silt and sand in some areas towards the west, adjacent to the Base (DME 1997).

TCC AREA

The TCC Area covered by this investigation includes the suburbs of Pallarenda, Rowes Bay, parts of Town Common, Belgian Gardens, West End, Mount Louisa, Garbutt, Mount St. John and Bohle.

The suburbs of Town Common, Pallarenda, Rowes Bay, Belgian Gardens, West End and Garbutt have an underlying geology of quartz sand with minor shells from beach barrier deposits overlain by silt and clay from intertidal deposits (DME 1997).

Garbutt is underlain by clay, silt, sand, gravel and flood plain alluvium (DME 1997). The lithology encountered during the DSI (WSP 2018a) was consistent with DME (1997). Silty/sandy clays were found to the maximum depth of investigation (11 metres below grade level (mbgl)) at Garbutt and a two metre interval of gravel was intersected in MW216, at Belgian Gardens, which may be representative of the fluvial sand and gravel hosted aquifers that have been reported to underlie the Late Holocene sediments (SKM 2008). The eastern part of Belgian Gardens and the northern section of West End are underlain by the Permian Castle Hill Granite, comprised of biotite leucogranite and microgranite with minor granophyre and granodiorite (DME 1997).

Mount St John has an underlying geology of Permian Julago Volcanics comprised of rhyolitic to andesitic lava, tuff, volcanic breccia, agglomerate, some conglomerate, sandstone, siltstone, shale and coal seams. It is overlain by Quaternary alluvium comprising of estuarine and alluvial clay, silt and sand; and further overlain by silt and clay from intertidal deposits (DME 1997).

Bohle has an underlying geology of Quaternary alluvium comprising of estuarine and alluvial clay, silt and sand; and further overlain by clay, silt, sand, gravel and flood plain alluvium. The northern part of Bohle is also underlain by silt and clay from intertidal deposits (DME 1997).

The sub-surface lithologies encountered during the DSI (WSP 2018a) across the suburbs of Garbutt, Mount Louisa and Bohle correlate with the Late Holocene coastal plains sediments comprising silts, clays and sands as described by SKM (2008).

Clayey sand and fine grained sand was identified at depths of 5 mbgl to 7 mbgl in several of the soil bores installed in the south of the IA (MW225, MW229 and MW236). It is possible that these sands may represent the top of the underlying fluvial sediments; however, this material does not appear to be significantly different to the sands found interbedded with the clays and silts on the Base. Therefore, for the purposes of site conceptualisation, these sands have been interpreted to be part of the Late Holocene coastal plains sediments. In the Town Common and at Belgian Gardens the sands were underlain by silty/sandy clays, indicating the sands become thinner further from the coast, pinching out approximately 1 km from the coast at Rowes Bay/Belgian Gardens and approximately 2 km from the coast in the Town Common.

ECOLOGICAL AREA

The Ecological Area of the IA consists of the Town Common, Shelly Beach, Bohle River estuary and banks upstream of the Bruce Highway.

The mountainous regions on the north side of Town Common have an underlying geology of Early Permian Julago Volcanics, comprising Rhyolitic to andesitic lava, tuff, volcanic breccia, agglomerate, some conglomerate, sandstone, siltstone, shale, and coal seams (DME 1997).


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The rest of the Ecological Area has an underlying geology of Quaternary (Holocene) alluvium comprising of silt and clay from intertidal deposits underlain by quartz sand and minor shells from beach barrier deposits (DME 1997). The southern area of the Town Common is underlain by estuarine and alluvial clay, silt and sand, and a small part of the Town Common is further underlain by Quaternary colluvium comprising of boulders and cobbles with interstitial sand and clay, and talus deposits.

2.3.4 HYDROGEOLOGY

BASE

SKM (2008) compiled groundwater data from previous investigations by ERM (2005) and Woodward Clyde (1999) and proposed that there are three distinct aquifers underlying the Base:

— A shallow perched unconfined aquifer in the western, north-western and northern sections of the Base, which is perched on shallow marine clays (approximately 1 mbgl to 2 mbgl). It is not known if the aquifer is discontinuous. Shallow groundwater is anticipated to form a direct connection with surface water in wetlands as base-flow.

— A middle, semi-confined aquifer located in Pleistocene to Holocene fluvial sand and gravel deposits (approximately 5 mbgl to 10 mbgl).

— A deeper, semi-confined aquifer located in sands and gravels associated with Quaternary paleo-channels located between 15 mbgl and 40 mbgl. From the previous investigations it is not known if a deeper aquifer exists within the basement granites.

From SKM’s (2008) report, it was observed that local coastal plain sediments consist of interdigitated riverine sand, beach sand, salt flat, mangrove and bay-mud sediments, which is a product of sea-level changes over the last 100,000 years. In turn, a complex series of aquifers are developed and usually interconnected in three dimensions, which contain weathered products of the parent rocks and anoxic muds. SKM’s (2008) groundwater monitoring investigation supported the Maunsell (2005) findings of the three-dimensional interconnection of the aquifers.

Groundwater contours derived by SKM (2008) showed a general groundwater flow direction to the west north-west with local easterly flows in the vicinity of NQ0099 Fuel Farm 2, located in the centre of the Base.

The findings of the DSI (WSP 2018a) led to a re-interpretation of the above hydrogeological conceptualisation. No evidence was observed to support the existence of a shallow perched aquifer in the top ‘one to two metres’ at the Base, including in the review of historical groundwater investigations. It is considered likely that the interbedded clays, silts and sands form a connected, semi-confined aquifer across the Base, with a water depth of approximately 1.5 mbgl to 2.5 mbgl. It is likely this semi-confined aquifer is at least partially connected to the underlying fluvial sand and gravel-hosted aquifers, which are reported to be present at a depth of 5 mbgl to 10 mbgl (SKM 2008), but were not confidently identified in this investigation (WSP 2018a).

The clay/silt/sand aquifer appears to have a depth of at least the maximum depth of investigation, which was 11 mbgl in Garbutt and 8 mbgl on-Base. Therefore, the clay/silt/sand aquifer has a thickness of at least 5.5 m to 9.5 m. This aquifer was intersected below the coastal sands on-Base, at the Town Common, Rowes Bay and in Belgian Gardens, and is likely to underlie the sands beneath the coastal sand dunes. Similar material was intersected at Bohle, suggesting that the unit extends across the entire coastal plain between the coastal sands and the outcropping granites and volcanics of Castle Hill, Mount Louisa and Many Peaks Range.

The sand-hosted aquifer in Cleveland Bay, Rowes Bay and Pallarenda had a maximum depth of 6.5 mbgl in MW210, which was the maximum depth of investigation in this area. The sand aquifer is likely to be several metres thicker in the centre of the sand dunes running parallel to the coast, thinning both eastwards and westwards. The eastern extent of this aquifer is not known, as it extends offshore beneath Cleveland Bay. The sand aquifer extends approximately 2 km inland in the Town Common and narrows to the south, extending approximately 1 km inland at the Base and 500 m inland at Rowes Bay and Belgian Gardens.

A groundwater bore search of the IA was conducted using the Department of Natural Resources and Mines (DNRM) groundwater database, accessed via Queensland Globe, which identified 23 registered groundwater bores within the IA.


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Details of the groundwater bores found within the IA are presented in Table 2.3 and locations of the registered bores are shown on Figure 6, Appendix A.

There are two registered bores within the Base itself (RN166762 and RN166765). RN166762 is located at the south-western corner between 5th Aviation Regiment (5 AVN) and Ingham Road. According to the groundwater database, the bore is a monitoring bore with a depth of 11 m, screened in silt with a standing water level (SWL) of 3.9 m with saline water reported. RN166765 was previously identified as an off-Base well, however, a comparison of the groundwater gauging record (MW140_D) and the registered bore card suggests this is an on-Base monitoring bore. The bore is screened through sand and sandy clay with a total depth of 13 m and a standing water level of 0.769 m as at April 2018.

A summary of the findings from the groundwater database available at Queensland Globe for the other areas in the IA are as follows:

TOWNSVILLE AIRPORT

Groundwater has a SWL of 1.6 m – 4.0 m AHD and was encountered in sandy clay with a yield of 0.2 litres per second (L/sec).

TCC AREA

— Garbutt: Groundwater was encountered between 4 m and 5 m in clay and sandy clay in the south-west area of the suburb. A more detailed groundwater report was recorded for well 175132. From this groundwater monitoring well, it was found that the aquifer details are recorded to be between 3 m and 6 m with a SWL at 4 m, with salty water (10 000 microsiemans per centimetre (µS/cm)) and yield of 0.8 L/sec.

— Rowes Bay: Groundwater north of the suburb, closer to the ocean side, has an aquifer above 4.0 m in sand, with SWL at 2 m and 4 m. The water encountered was of potable and fresh quality with yields around 0.2 L/sec. Groundwater on the south of the suburb was encountered in between the 7 m and 9 m layer with salty water and a yield of 12.6 L/sec.

ECOLOGICAL

No groundwater information was available for the Ecological Area.

Table 2.3 Registered groundwater monitoring bores within the IA

BORE ID LOCATION STATUS AND PURPOSE TOTAL DEPTH (mbgl)

STANDING WATER

LEVEL (mbgl)

SCREEN INTERVAL

(m)

153310 TCC; Garbutt. ~380 m south of Base

Existing. Sub-artesian monitoring.

7.0 – 3.0



7.0 – 3.0



7.0 – 3.0


Abandoned and destroyed. Water supply.

7.5 – –



7.5 – 3.0



7.2 – 2.7



7.2 – 3.0


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BORE ID LOCATION STATUS AND PURPOSE TOTAL DEPTH (mbgl)

STANDING WATER

LEVEL (mbgl)

SCREEN INTERVAL

(m)



7.2 – 3.0



7.2 – 3.0



7.2 – 3.0



7.2 – 3.0

153364 TCC; Garbutt. ~780 m south-west of Base


7.0 – 3.0

153365 TCC; Garbutt. ~780 m south-west of Base


7.0 – 3.0

175132 TCC; Garbutt. ~850 m east of the Base

Existing. Water supply. 14.0 4.0 5.0

166772 TCC; Rowes Bay. ~840 m NE of the Base


166731 TCC; Rowes Bay. ~1 km NE of the Base


166681 TCC; Belgian Gardens. ~1.5 km NE of the Base


73.0 – –

166975 TCC; Rowes Bay. ~1.3 km E of the Base

Existing. Water supply. 9.0 2.0 –

140410 TCC; Bohle. ~3.8 km SW of the Base

Abandoned and destroyed. Stratigraphic investigation.

48.0 – –


Existing. Water supply. 21 4.0 6.0



3 – –

166765 Townsville Airport, east, near the border of the Base

Existing, Sub-artesian monitoring.

13.0 1.60 11.0

166762 Base. Southern border Existing, Sub-artesian monitoring.

11.0 3.90 6.0

The DNRM bore card lithologies support the geological findings above. The bores located in Garbutt are generally screened in clay, with some sandy clay and coarse sand/gravel at a depth >9 mbgl in RN175132. The bores in Rowes Bay are screened in sand, with granite intersected in RN166975 at a depth of 12 mbgl.


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2.3.5 GROUNDWATER USE

According to the DNRM groundwater database, five of the existing registered bores in the IA are recorded as being used for “water supply”. As part of the DSI (WSP 2018a), a Water Use Survey was distributed to all properties within the IA. Participation in the survey was voluntary and not all questions were mandatory. As at 30 September 2018, 168 Water Use Surveys have been received via mail, email, phone and in person. Twenty-eight respondents to the survey indicated that they had bores on their property, 22 of which were operable and 18 of which were actively in use for water supply.

With the exception of two residents in Pallarenda and one resident in Garbutt, all landholders who responded regarding the use of extracted groundwater on their properties stated that the water was not used for drinking or domestic use. The two Pallarenda residents indicated they used their bore water “intermittently” on their vegetable gardens, with use limited to watering lawns and gardens. The resident in Garbutt indicated they used their bore water to water fruit trees and lawns but not their gardens.

Resident’s extraction bores were either in disuse or connected directly to garden/lawn irrigation systems and/or hoses.

One resident identified that the previous owner of the property had used groundwater to fill their swimming pool. No extracted groundwater was identified to be stored in tanks.

High salinity is likely to preclude potable domestic use of groundwater in the areas of Garbutt, Mount St John and Bohle; however, bores located in Rowes Bay and Pallarenda may have potable water quality. Although all properties in the IA are within the TCC and are therefore likely to be connected to reticulated town water, the use of fresh bore water for domestic water and drinking cannot be discounted.

2.3.6 SURFACE WATER

The IA has three main surface water catchments, the Bohle River drainage sub-basin, Three Mile Creek and Mundy Creek (Figure 4a and 4b, Appendix A). The surface water setting of each area of the IA is described as follows:

BASE

An investigation of the Base hydrology by SMEC (2012a; 2012b) reported:

— There are three main sources of water that flow into the Base, including Louisa Creek, Peewee Creek and Mount St John Drain. The main inflow comes from Louisa Creek, with an upper catchment of approximately 745 ha and high peak flows with little potential for ground infiltration due to the topography, which is generally flat and urbanised.

— Peewee Creek drains a mostly urban catchment of 156 ha to the south-east of the Base. It is a small urbanised water course that terminates at Ingham Road and flows into Louisa Creek via culverts under Blakey Street; however, in high flow events it flows directly into the Base, overtopping Ingham Road.

— Drainage of a catchment to the west enters the Base through the Mount St John Drain. The Mount St John Drain is separated from Louisa Creek by an elevated ridge line and the Mount St John water treatment plant (WTP). The primary flow path of the drain is north, away from the Base; however, in high flow events there is potential for flow to back up around the ridge line into Louisa Creek, impacting the Base.

— The internal catchment of the Base catchment is approximately 700 ha, most of which drains towards the north-west into the Louisa Creek flood plain and the Bohle Estuary. The catchment is made up of mostly mixed grassed and wetland areas, including Lake Lydeamore, with the remainder being buildings and hardstand. There are localised drainage issues within the south-western section of the Base due to the concentrated proportion of impervious area (5 AVN) and minimum hydraulic capacity of the drainage network. The on-Base wetlands are generally internally draining, only discharging at times of heavy rainfall, as was observed during the March rainfall sampling event.

Four other known catchments exist on the Base:

— A network of drains in the south-east corner of the Base flow off-Base to the east and then north into the Mundy Creek catchment and, in turn, Rowes Bay. The catchment consists of a mixture of hardstand, buildings and grassed areas, the largest grassed area being the former firefighting grounds (NQ0054).


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— A drainage network runs north between the ordnance loading aprons (OLAs) and Runway 01/19, which discharges from the Base through valved pipework on the Base’s northern boundary. The discharge then runs northerly through a network of wetlands past the Rowes Bay Golf Club and into Three Mile Creek. A drain runs along the Base’s eastern boundary at the northern end of the Base beyond Runway 01/19 and discharges at the Base’s north-eastern corner into the wetlands that run north past Rowes Bay Golf Club.

— A drainage network runs north between Runway 01/19 and the eastern boundary of the Base. These drains run north and south and discharge into the drain at the end of Old Common Road. This watercourse flows east into Mundy Creek and then Rowes Bay.

— The area to the north of Runway 01/19 along the eastern boundary of the Base appears to drain east into the watercourse that runs south-east to the north of the Belgian Gardens Cemetery, joining Mundy Creek before flowing into Rowes Bay.

Sections of the Base adjacent to the runways subject to inundation have pumping networks designed to prevent flooding of the runways. Surface waters are pumped from sumps into the wetlands on the western, north-western and northern sides of the Base. The pumps were operational during the discharge sampling event in March 2018. One of the pump locations was specifically sampled (SW102).

TOWNSVILLE AIRPORT

As Townsville Airport shares the same runway (Runway 01/19) as the Base, the drains near the runway and on the eastern border of the Base, run through Townsville Airport, into Rowes Bay and exit at Mundy Creek.

TCC AREA

— At the northern suburb of Pallarenda, Three Mile Creek runs from the Town Common and branches-out south towards Rowes Bay and the mouth of the Creek into the ocean, north of Rowes Bay Park. The watercourse is part of the Bohle drainage division.

— Drainage from the eastern and northern parts of Garbutt, Belgian Gardens and the northern part of West End run through a network of drains to the north, joining Mundy Creek and running into Rowes Bay.

— There are two perennial lakes within the suburb of Bohle; one located north-west of the suburb, bordering the Town Common, and another on the south-west corner, bordering Cosgrove. Bohle is adjacent to the Bohle River, and has major watercourses (Louisa Creek and canals running from Mount Louisa) running on the east, south and west side of the suburb. A perennial lake located on the north-west corner of Cosgrove, approximately 150 m east of the Bohle River, is also included in the IA.

— There are canals running through the south-western section of Garbutt, which flow west into Peewee Creek, which then flows north from Mt Louisa, joining Louisa Creek in the wetlands to the west of the Base.

— Within the suburb of Mount St John, rural water storage is located south-west of the suburb, north of Crocodile Crescent. Canals/drainage flowing from Mount Louisa terminate on the south side of Mount St John. Drainage and some canals also run through the perimeter of the industrial area, north of Mount St John. The canals on the northern section flow into Louisa Creek. These canals relate to the drainage catchment to the west of the Base mentioned previously.

— The south-western section of Garbutt and most of the suburb of West End drain to the south, entering the unnamed lake between Ingham Road and Woolcock Street, which overflows eastward into National Creek. National Creek joins Ross Creek approximately 1.5 km east of the IA, which then flows north-east, entering Cleveland Bay at the Port of Townsville.


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ECOLOGICAL AREA

The Ecological Area of the IA includes a large part of the estuarine system and drainage from the Bohle River, including Peewee Creek, Louisa Creek, and Three Mile Creek. Within the Town Common, a 1.07 ha perennial lake is located near Causeway Road and Freshwater Lagoon Road. There were approximately three rural water storage areas in the Town Common, which now act as natural lagoons. The Town Common receives surface water run-off from the Base and from the TCC suburbs of Bohle, Mount Louisa and part of Garbutt.

2.3.7 FLOOD HAZARD

The Townsville City Plan (TCC 2017) was reviewed to provide an indication of the likelihood of flooding in the IA. The City Plan flood hazard overlay’ which is presented in Figure 2.1, shows that significant areas of the Base and the IA have been mapped as ‘high flooding hazard’ (dark blue) or ‘medium flooding hazard’ (blue). The flood mapping has defined the high hazard areas to have a 2% annual exceedance probability (AEP) and the medium hazard areas to have a 1% AEP. The flood mapping indicates that low-lying areas of the IA are potentially subject to regular inundation.

Figure 2.1 Flood overlay of IA (Townsville City Plan 2017)

2.3.8 SURFACE WATER – GROUNDWATER INTERACTIONS

Studies undertaken by SKM (2008) showed that groundwater levels in the western area of the Base (former bore RAAFTVL001 and monitoring well MW057 – Figure 10a and 10b, Appendix A) increased by approximately 0.6 m within three to eight days of an 80 mm rainfall event. This indicates the intimate connection between surface water and groundwater in the IA, resulting from the permeable near-surface soils and shallow groundwater table. Large areas of grassed ground, including unlined surface drains, provide substantial groundwater recharge for the shallow aquifer. Groundwater infiltration from the wetlands on the Base and in the Town Common is also likely. Potential surface water – groundwater interactions in the IA are likely via:


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— rainfall infiltration from the grassed areas of the runway surrounds and between infrastructure on the Base — leakage/seepage from unlined drains on-Base and drainage channels running from the eastern boundary of the Base

into the Mundy Creek catchment — infiltration from standing water bodies on-Base (Lake Lydeamore), Louisa Creek wetlands and overland flow during

wet season events — infiltration from wetlands in the Town Common and the upper reaches of Three Mile Creek and Mundy Creek.

These wetlands receive surface runoff from the Base, which may present a pathway for PFAS transported by surface water from the Base to infiltrate into the underlying groundwater at a distance from any secondary sources at the Base

— at times when the groundwater table is elevated groundwater is likely to seep into some drains on Base and the lower reaches of Mundy Creek.

2.3.9 SENSITIVE LOCAL ENVIRONMENTAL RECEPTORS

Sensitive receptors are people or organisms that may be adversely impacted by exposure to chemicals in the environment. Environmental receptors are non-human sensitive receptors.

Surface water from the Base drains directly into Peewee and Louisa Creeks and the Town Common to the Base’s west and north-west, eventually discharging to Halifax Bay via the Bohle River estuary. Drainage from the north of the Base flows into the Three Mile Creek catchment and runoff from the east of the Base drains into the Mundy Creek catchment; both of these creeks discharge into Rowes Bay. The sensitive environmental receptors identified in proximity to the Base are:

— The Town Common — Louisa Creek and associated wetlands (including Peewee Creek) — Three Mile Creek and associated wetlands — Mundy Creek and associated wetlands; and — Bohle River.

Whilst Halifax Bay and Rowes Bay receive waters from the receptors identified above, the bays were not considered potential sensitive receptors for the DSI until it could be demonstrated (or otherwise) that the immediate receptors contained PFAS impact.

The majority of the Town Common is designated a Conservation Park under the Nature Conservation Act 1992. The Town Common and the estuarine reaches of the Bohle River are part of the Bohle River Fish Habitat Area (FHA-027), which is designated ‘Management Level B’ (DNPRSR 2012) for its importance to recreational, traditional and commercial fisheries (NPSR 2012) (Figure 2.2). No part of the IA is designated ‘Management Level A’. The estuarine reaches of the Town Common and Bohle River, including the on-Base wetlands to the west and south of the OLAs, are mapped as having very high and high aquatic conservation values respectively under the Queensland Aquatic Conservation Assessment (AquaBAAM) mapping (Rollason and Howell 2012) (Figure 2.3). The freshwater wetlands are mapped as having high ecological significance and matters of State environmental significance (MSES) under the State Planning Policy (SPP) (DILGP 2017).

The Town Common is classified ‘Category B – Remnant vegetation’ on the Regulated Vegetation Management Map, with a section at the centre of the Town Common classified as ‘Essential Habitat Category A or B’ (Figure 2.4). The lower reaches of the Bohle River are classified as ‘Category R – Reef regrowth watercourse vegetation’.

A review of previous ecological assessments (AECOM 2015) and database records demonstrates that the Town Common and Bohle River support a diverse community of commonly occurring aquatic biota and variety of aquatic habitats including freshwater wetlands and waterways, and estuarine wetlands and waterways (supporting mangroves, saltmarsh and claypans).


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The wetlands in the upper reaches of Three Mile Creek between the Base and the former Rowes Bay Landfill are mapped as having high aquatic conservation values under AquaBAAM mapping (State of Queensland 2017) (Figure 2.3). The lower reaches of Three Mile Creek are also included in the Bohle River Fish Habitat Area (Figure 2.2). Portions of the Three Mile Creek and Mundy Creek wetlands are classified ‘Category B – Remnant vegetation’ on the Regulated Vegetation Management Map, with the banks of the lower reaches classified as ‘Category R – Reef regrowth watercourse vegetation’ (Figure 2.4).

Figure 2.2 Fish habitat areas (NPRSR 2012)

Figure 2.3 Aquatic ecological conservation assessment map (Rollason and Howell 2017)


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Figure 2.4 Regulated vegetation management map (RVM category C – high value regrowth vegetation is not

present in the figure)

2.4 PROPERTIES OF PFAS PFAS and their derivatives have been used in industrial processes and consumer products since the 1950s. Uses relevant to the DSI include AFFF for firefighting and training and in aviation hydraulic fluid. There are at least 3,000 PFAS on the global market, with an estimated 200 to 600 different chemicals believed to occur in, or result from AFFF (Wang et al, 2017). The primary AFFF product in use at Defence sites prior to 2005 was 3M Lightwater™, which is known to contain several PFAS compounds, including PFOS and PFOA. Ansulite® replaced 3M Lightwater™ at Defence sites after 2005 (DoD 2007). 3M Lightwater™ and Ansulite® are the only AFFF products known to have been used at the Base.

The PFAS compounds that are most commonly found in the environment and for which the most scientific information exists are PFOS, PFOA and PFHxS (CONCAWE 2016, CRC CARE 2107) and are analytes for which Australian-derived PFAS screening criteria exist. The following sections summarise the key physical and chemical characteristics of PFAS relevant to the investigation, focussing on the better-known species, PFOS, PFOA and PFHxS.

2.4.1 PHYSICAL AND CHEMICAL PROPERTIES OF PFOS/PFOA/PFHXS

PFOS, PFOA and PFHxS are manufactured chemicals that are chemically and biologically stable and hence are persistent in the environment. The compounds are resistant to biodegradation, atmospheric photooxidation, direct photolysis and hydrolysis (US EPA 2014).

PFAS are moderately to highly soluble in water; PFHxS and PFOA are highly soluble and PFOS is moderately soluble (CONCAWE 2016). Therefore, PFOS, PFHxS and PFOA are readily dissolved/leached from soils by infiltrating rainwater, surface water or groundwater. Their resistance to hydrolysis leads to persistence and long half-lives in water (CRC CARE 2017). Many PFAS appear to show little chemical/physical retardation (adsorption and/or degradation) during transport, probably due to their hydrophobic and lipophilic end groups; however, they have been found to partition from the groundwater into sediments and/or soils rich in organic matter due to their propensity to sorb to natural organic matter (CRC CARE 2017).

Biodegradation of PFAS compounds is not known to occur; however, microbial degradation or metabolic processes of larger organisms can form PFOS and PFOA through the breakdown of longer-chain ‘precursor’ compounds or related substances (CRC CARE 2017).


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PFAS compounds generally have low volatility; however, transport of PFAS for considerable distances as aerosols or dust particles may be possible because of their long atmospheric half-lives (US EPA, 2014).

The combination of the above physical and chemical characteristics results in PFAS being readily transported from primary and secondary (soil and sediment) sources via groundwater and surface water with little to no concentration decrease from adsorption or degradation. This has led previous investigations (e.g. AECOM, 2016c) to consider PFOS and PFOA to be persistent chemicals in the environment and assume no chemical retardation of contaminant migration for assessment purposes.

Key physical and chemical properties of PFOS, PFOA and PFHxS are listed in Table 2.4.

Table 2.4 Chemical and physicochemical properties of PFOS, PFOA and PFHxS

PROPERTY PFOS PFOA PFHXS

Formula of typical substance C8HF17O3S C8HF15O2 C6HF13O3S

Appearance at normal temperature and pressure

White powder (potassium salt) White to off-white powder White crystalline powder

Molecular mass (g/mol) 500.13 414.07 400.12

Melting point (°C) 54 (potassium salt) 37–60 No known data

Boiling point (°C) 258–260 (potassium salt) 192.4 114.7

Density at 20°C (g/mL) ~ 0.6 (potassium salt) 1.792 1.84

Water solubility at 25°C (mg/L)

520–570 3,400–9,500 2,300

Octanol-water partition coefficient (log Kow)

6.43 5.3 5.17

Acid disassociation constant (pKa)

~ 3.3 (estimated) Debated (0.5 estimated, 2.8–3.8 reported)

0.14

Organic-carbon partition coefficient (log Koc)

2.57–4.2 2.06–3.7 1.78

Henry’s Law constant (atm-m3/mol)

3.05 x 10-9 Not measurable Not available

Air/water partition coefficient

<2 x 10-6 Not available Not available

Source: (DoH, 2017; CRC CARE, 2017, CONCAWE, 2016) Notes: g/mol – grams per mole; °C – degrees Celsius; g/mL – grams per millilitre; mg/L – milligrams per litre; atm-m3/mol – atmosphere – cubic metres per mole.


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2.4.2 KEY PFAS MIGRATION PROCESSES AT THE IA

As PFAS is generally highly soluble and persistent in water, PFAS is liable to be transported by surface waters from primary sources and leached from secondary sources by infiltrating rainfall into underlying groundwater and/or surface waters and further transported through these media. Potential PFAS source areas are discussed in Sections 3 and 4.

The key migration processes for PFAS impacted water at the Base and throughout the IA include:

— surface water drainage on-Base via Peewee Creek in the Base’s south-west portion — surface water drainage off-Base to the north-west into the Louisa Creek and Town Common catchments via Peewee

Creek, piped networks, concrete lined drains and unlined, grassed channels — surface water drainage off-Base to the north-east into the Mundy Creek catchment via piped networks, concrete lined

drains and unlined, grassed drains — surface water drainage off-Base to the north into the Three Mile Creek catchment via concrete lined drains and

unlined, grassed drains — discharge of excess overland flow from the runway areas via pumping to the Town Common and Three Mile Creek

catchment; and — groundwater transport via the shallow, unconfined aquifer in the north and north-west of the Base and the semi-

confined sand and gravel-hosted aquifer across the remainder of the Base.

PFAS may also be transported through the air as aerosols and dust particles. The relative importance of the contribution to transport fluxes by this mechanism are not well understood, but are considered likely to be significantly lower when compared with transport by surface water and groundwater.

PFAS precursors may be converted into PFOS and PFOA through metabolic processes in fauna (enHealth 2016). PFAS precursors transported by surface water or groundwater downgradient may be converted to PFAS/PFOA at a distance from the source.

2.4.3 PFAS ANALYSIS AND DATA INTERPRETATION CONSIDERATIONS

The Seasonal Monitoring Report 1 has considered PFAS analysis from a range of media (water, soil, sediment and biota). The investigation has been designed to minimise uncertainty wherever possible. Potential sources of uncertainty and the strategies employed during this investigation to minimise uncertainty are detailed in Table 2.5. Additional quality assurance (QA) and quality control (QC) considerations are included in Appendix C and additional information regarding the laboratories used for the Seasonal Monitoring Report 1 are included in Section 7.9.

Table 2.5 Potential uncertainties in PFAS analysis and interpretation

ASPECT POTENTIAL UNCERTAINTY INVESTIGATION STRATEGY

Accuracy of analytical techniques

The analytical techniques for many of the PFAS compounds considered in this investigation are relatively new and inaccuracies in the results may result from variability in implementing these new techniques.

Australian Laboratory Services (ALS) were used as the primary laboratory for all analyses and Eurofins MGT were used as the secondary laboratory for all secondary analyses. Both laboratories are National Association of Testing Authorities (NATA) accredited for all compounds analysed.

Extensiveness of analytical suite

There are estimated to be over 3,000 PFAS compounds in existence, 200 to 600 of which have been used in AFFF (Wang et al 2017). At the time of the Seasonal Monitoring Report 1, commercially available analytical techniques in Australia were limited to 28 species.

The entire available commercial PFAS suite, as recommended by Golders (2017) and DoD (2018) was analysed in the Seasonal Monitoring Report 1. Approximately 1 in 20 samples was also analysed for TOP assay to provide an indication of the potential concentration (if any) of unknown PFAS compounds present in the samples.


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Low assessment criteria

The available published assessment criteria adopted for the DSI are at sub-microgram per litre levels. At such low concentrations, very small absolute differences in concentrations may appear as seemingly large relative differences between results.

Consideration of the very low level of reporting and assessment criteria have been made when comparing results between sample locations, sampling events and duplicate/triplicate pairs.

Short timeframe of DSI

Natural fluctuations in PFAS concentrations in waters may not be evident in the limited number of sampling events in the DSI / Seasonal Monitoring Report 1 which has been limited to one dry and one wet season event.

Historical data on the Base, where available and reliable, has been incorporated into the Seasonal Monitoring Report 1. No historical information is available for PFAS contamination off-Base. Potentially, years of sampling are required to gain a full understanding of the variation of PFAS within surface and groundwater in the IA.

The potential variability in the data has been taken into account when interpreting the results of the Seasonal Monitoring Report 1 to allow an assessment of potential risk to be made within a realistic timeframe.

Historical data The historical data from on-Base used in the DSI (WSP 2018a) was collected by a variety of consultants at different times who may have used differing sampling techniques, different laboratories and may have had different objectives for the collection of their samples. This may have introduced uncertainty into the historical data compared with results gained during the Seasonal Monitoring Report 1.

The historical data has only been used to gain an understanding of the longer-term trends of PFAS in the surface water and groundwater at the Base and to develop the CSM. Only results gained from the DSI (WSP 2018a) and the Seasonal Monitoring Report 1 have been used in the interpretation of the nature and extent of PFAS impact in the IA, the refinement of the CSM and to inform the HHRA and ERA.

Background concentrations

Ongoing research has determined that PFAS is prevalent throughout the environment, with many industrial and domestic sources other than AFFF. Unidentified off-Base sources of PFAS may confound the results of the Seasonal Monitoring Report 1.

A desktop investigation was undertaken to identify off-Base sources of PFAS in the vicinity of the Base and to inform the extent of the IA. Background wells were installed up-gradient of the Base to determine background concentrations of PFAS in the IA. Chemical results were investigated to identify any PFAS signatures that could be used to discriminate between differing sources of PFAS in the IA.

Mixing Zones The receiving surface waters at Townsville are tidal in their lower reaches. This results in a mixing zone with seawater inflow that may result in dilution, spread of PFAS into reaches of the estuaries and deposition of PFAS due to salinity increases. Surface waters from upstream also mix with surface water discharges from the Base, leading to mixing with waters that may have background concentrations of PFAS.

Sampling locations have been positioned to include up-gradient areas and potential estuarine mixing zones in the Bohle River, Louisa Creek and Mundy Creek catchments. This will characterise background and estuarine mixing zone PFAS distributions.


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Cross contamination

PFAS is used in many products such as water-proof clothing, food packaging and plastics. The potential for cross contamination of samples exists during sample handling, particularly if PFAS containing products (e.g. Teflon-lined sample jars) are used in investigations.

Sampling methodologies took into account the presence of PFAS in many products and methodologies and controls were specifically developed for the Seasonal Monitoring Report 1 to minimise the potential for cross contamination (refer Section 5.2).

2.5 THE INVESTIGATION AREA, CONTAMINANT CHARACTERISTICS AND LIMITATIONS OF THE SEASONAL MONITORING REPORT 1

The IA covers a large (7,784 ha) area with variable site uses and physical characteristics, including a complex history of human activity over the past 50 years. This, combined with the complicated chemical and physical behaviour of PFAS compounds, was considered likely to lead to technical limitations of the Seasonal Monitoring Report 1.

The characteristics of these potential limitations and the strategies employed to minimise uncertainties associated with the limitations are detailed in Table 2.6.

Table 2.6 Characteristics of potential limitations and strategies employed

ASPECT POTENTIAL LIMITATION INVESTIGATION STRATEGY

Scale and complexity of IA

The IA covers over 7,700 ha of terrestrial and estuarine environment with environmental settings varying from light industrial and commercial, low density residential and highly disturbed ecosystems comprising wetlands, saline flats and estuarine waterways. Hydrological and hydrogeological knowledge of the area, particularly off-Base, is limited. Thorough coverage of the entire IA is impossible given acceptable timeframes and knowledge gaps are likely to persist at the completion of the Seasonal Monitoring Report 1.

The Seasonal Monitoring Report 1 has been designed with the specific objective of targeting potential receptors and gaining sufficient information on PFAS pathways to these receptors to inform whether human health or environmental impacts from PFAS is likely to occur. Interpolation and interpretation between data points is commonly undertaken in contaminated land investigations and is likely to be required for the Seasonal Monitoring Report 1.

Limited knowledge of PFAS and complexity of behaviour

Many PFAS compounds are believed to exist in the environment with different chemical and physical properties and different behaviours in the environment; however, little is known about the vast majority of them.

The Seasonal Monitoring Report 1 objective was to gain a better understanding of the nature and distribution of PFAS in the IA following the wet season, particularly with regard to potential receptors. The Seasonal Monitoring Report 1 is constrained by current scientific knowledge and commercially available analytical methods.


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ASPECT POTENTIAL LIMITATION INVESTIGATION STRATEGY

Source complexity

Multiple potential sources of PFAS exist across the IA, particularly on the Base. A history of unrecorded AFFF use and storage has resulted in uncertainty regarding the specific quantity and location of PFAS sources at the Base. Despite numerous previous investigations at the Base, potential uncertainties remain.

The DSI included a detailed desktop historical review of available information and involved interviews with personnel with historical knowledge of Base operations. This provided a better understanding of the extent and relative importance of different source areas, including the identification of new potential source areas to the extent practicable.

Access limitations

Areas of the IA could not be accessed due to flooding, ground conditions (wetlands) or health and safety concerns (high grass and snake risk).

Where possible, locations that proved to be inaccessible were re-located to the nearest safely accessible location that would serve the purpose of the originally planned location.


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3 SITE HISTORY REVIEW A limited historical review of the Base and IA was undertaken as part of the DSI to establish historical activities and use of the Base, with a focus on the known and potential storage, handling and use of AFFF (WSP 2018a). A summary of the findings of the historical review follows.

The Base was established during World War II, in the early 1940’s. The civilian airport was established in 1964. Significant developments at the Base include the development of 5 Aviation (5 AVN) in the 1970’s, expansion of 5 AVN and the civilian terminal in the early 1990’s and the construction of the OLAs and 38 Squadron (38 SQN) between 2000 and 2001.

The aerial photographs show that the residential portions of the suburbs of Garbutt and Belgian Gardens have been generally unchanged from the 1960s, whereas the suburbs of Rowes Bay and Pallarenda reached their current extents in the 1970s. The industrial section of Garbutt, Mt Louisa and Bohle were largely developed in the 1980s and 1990s, whereas Mount St John was developed in the 2000s, including the Mount St John WTP. The Town Common has remained relatively unchanged since the earliest aerial photograph of that area (1961).

The review and interviews undertaken by WSP (2018a) identified the following on-Base activities involving AFFF that may have contributed to PFAS impact of soil, surface water and groundwater:

— storage and handling of AFFF — fire training activities at designated (e.g. fire training grounds) and non-designated areas (e.g. fuel storage areas) — firefighting activities at incidents where there was a potential for fuel ignition — routine operation of fire deluge systems; and — discharges from water treatment plants.

Previously identified sources of PFAS soil and groundwater impact were confirmed and further characterised at the following locations across the Base:

— historical fire training at the former fire training ground NQ0106 — unknown activities, possibly equipment testing and sparging of fire truck tanks at Fuel Farm 2 NQ0099 — historical fire training, equipment testing and sparging of fire truck tanks and AFFF spills at the fire station NQ0055 — accidental discharges and spills from AFFF-containing fire deluge systems in hangars (Buildings 236 and 295) at

5 AVN — historical fire training and equipment testing and purging at the former fire training ground NQ0054 — historical fire training at the former fire training ground NQ0105 — historical fire training and AFFF spill at Pad Brahman — historical fire training, sparging of fire truck tanks, AFFF spills and storage of PFAS impacted soil at disused

Runaway 13/31 — historical fire training by cadets and production of foam as part of Open Day demonstrations at the former Cadet

training area — possible emergency responses adjacent to Runway 07/25 and Runway 01/19 — historical fire training activities at former fire training ground NQ0107 — equipment testing and AFFF storage at the 5 AVN wash point (Building 366) and Ground Support Equipment (GSE)

compound; and — historical production of foam as part of Open Day demonstrations at the Ingham Road sports fields.


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The desktop review identified a number of off-Base facilities and operations in the IA that may have been/be potential sources of PFAS. The following operations and facilities have either potentially stored and/or used AFFFs, or may have treated PFAS contaminated water:

— Woodland Fire Station, at 1 Cosgrove Drive, Cosgrove, where AFFF storage and fire training may occur. — Queensland Fire and Emergency Services Northern Region Mechanical Workshop (38–40 Auscan Crescent,

Garbutt), where AFFF storage and fire training may occur. — North Queensland Resource Recovery at 77–103 Enterprise Street, Bohle, where treatment of PFAS impacted soil

and water may have occurred (with trade waste potentially being sent to the local water treatment plant). — Chubb Fire and Safety at 10–11 Trade Crescent, Bohle, where AFFF storage may occur. — Mount St John WTP, Mount St John Road, Mount St John, where treatment of PFAS-impacted water may have

occurred. — Former Bohle WTP, formally located at 64 Enterprise Street, Bohle, which was operational prior to the

commissioning of the Mount St John Water Treatment Plant and may have treated PFAS-impacted water. — Rowes Bay Golf Club, Cape Pallarenda Road, Rowes Bay, which receives treated water from the Mount St John

WTP for irrigation purposes. The efficacy of PFAS removal from water by the WTP is unknown.

No known industrial fires or industrial activities that may have involved the use of AFFF or the generation of products using PFAS chemicals are known to have occurred in the IA.

3.1 PREVIOUS INVESTIGATIONS Previous investigations relevant to PFAS assessment and contamination at the Base are listed below. The key outcomes of these reports and other reports reviewed as part of the investigation are summarised in the DSI report (WSP 2018a).

— Woodward Clyde, 1999. RAAF Base Townsville Redevelopment Environmental Impact Assessment (EIA) Volumes 1 & 2, Section 15-C Site Contamination.

— SKM, 2008. RAAF Base Townsville, Department of Defence, Stage 2 Environmental Investigation. — ENSR, 2008. Groundwater Sample Report for RAAF Base Townsville – Sampled 8–18 July 2008. — ENSR, 2009b. Groundwater Sample Report for RAAF Base Townsville – Sampled 3–7 November 2008. — ENSR, 2009c. Water Monitoring Program for RAAF Base Townsville, Annual Report (NQ1998). — ENSR, 2009d. RAAF Townsville Environmental Monitoring Program for Water Quality (NQ1998). — GHD, 2009. Report for MRH-90 Facilities Upgrade, Site Contamination and Acid Sulfate Soil Assessment. — GHD, 2011. Report for AZ4561 Environmental Investigation of Fire Training Areas, RAAF Base Townsville. — NRA, 2012. NQ2340, Surface Water Sample Report for RAAF Base Townsville. — Golder, 2012a. Initial Investigation Report, BQ2125.05 – RAAF Base Townsville. — Golder, 2012b. Townsville RAAF Base MRH Stage 6 – AFFF Assessment, Structure 271. — AECOM, 2012. RAAF Base Townsville 5th Aviation Regiment, Facility 271, Pre-Works Contamination

Assessment. — AECOM, 2013a. RAAF Base Townsville 5th Aviation Regiment Pollution Control Project (NQ2305) Pre-Works

Contamination Assessment – Addendum relating to Excavations to the East of Hangar 295. — AECOM, 2013b. RAAF Base Townsville 5th Aviation Regiment Pollution Control Project (NQ2305) Pre-Works

Contamination Assessment – Addendum relating to Excavations to the West of Hangar 295. — NRA, 2013. Surface Water Monitoring, NQ2809.01-RBT (0874) Relocation of Contaminated Soils. — NRA, 2014. NQ2802 Surface Water Sample Report for RAAF Townsville, 2 February 2017. — AECOM, 2016a. Spoil Management Plan – Part B, Defence DFI Remediation, RAAF Base Townsville. — AECOM, 2016b. RFI NQ – Spill Pond Update (RAAF TVL). Email to FKG Gardner, 1 April, 2016. — Jacobs, 2016a. North Queensland Water Quality Monitoring, Department of Defence, RAAF Townsville

Groundwater Monitoring Report, Post Dry Season.


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— Jacobs, 2016b. North Queensland Water Quality Monitoring, Department of Defence, RAAF Townsville Groundwater Monitoring Report, Post Wet Season.

— Jacobs, 2016c. North Queensland Water Quality Monitoring, Department of Defence, RAAF Townsville Surface Water Monitoring Report.

— GHD, 2016. Defence per- and pol-fluoralkyl Substances (PFAS) Environmental Management Preliminary Sampling Program, Final Report.

— WSP, 2018a. RAAF Base Townsville Detailed Site Investigation – PFAS, Volume 1: Main Report. — WSP, 2018b. RAAF Base Townsville Human Health Risk Assessment.

3.2 POTENTIAL IMPLICATIONS OF PFAS EXPOSURE In April 2017, the Commonwealth Department of Health (DoH) released health based guidance values for PFAS substances for use in site investigations in Australia (DoH 2017). The guidance values were established using the findings of the Food Standards Australia New Zealand (FSANZ) report Perfluorinated Chemicals in Food (FSANZ 2017).

The findings noted that there is no consistent evidence that exposure to PFAS causes adverse health effects in humans. However, due to the fact that these chemicals persist in humans and the environment, it was recommended that human exposure to these chemicals be minimised. The health based guidance values are a precautionary measure to protect human health while further research is conducted into the potential health impacts of PFAS (DoH, 2017).

Water-borne PFAS exposure has been shown to be toxic to freshwater and marine aquatic organisms, resulting in adverse effects on reproduction, immunology and development in exposed organisms (CRC CARE, 2017). Less information is available on the potential effect of PFAS exposure on terrestrial organisms.


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4 DSI CONCEPTUAL SITE MODEL Information obtained during the DSI (WSP 2018a), including desktop investigations, interviews with current and former Base personnel, review of previous investigations and publicly available information and a general inspection of the Base and IA (as presented in Sections 2 and 3), was used to prepare a preliminary CSM.

This preliminary CSM was updated following the DSI (WSP 2018a) field works and receipt and interpretation of laboratory analysis. A summary of the DSI is presented in Section 4.2. The CSM was refined following the Seasonal Monitoring Report 1 (Section 9).

4.1 DEFINITION OF SOURCE-PATHWAY-RECEPTOR LINKAGES

In accordance with national guidance on the assessment and management of contaminated land (NEPC 2013), potential risks to receptors are based on three components:

— Source: a potentially hazardous substance that may be released to the environment (PFAS in the context of this Seasonal Monitoring Report 1).

— Pathway: a mechanism by which the hazardous substance may reach and be exposed to receptors. — Receptors: person(s) or ecosystem(s) that may be detrimentally affected by exposure to the hazardous substance.

If all three components are present in a system, the source-pathway-receptor linkage is considered complete and a receptor is potentially at risk. If one of the components is absent, no risk is present.

4.2 DSI CSM The CSM is summarised in Table 4.1.

Table 4.1 DSI CSM

LIKELY SOURCES OF PFAS IMPACT

Likely sources of impact at the Base are listed below: — Fire training activities at designated (e.g. fire training grounds) and non-designated areas

(e.g. fuel storage areas), including spill emergency response and equipment cleaning: — Aircraft washing facility and fire training ground (NQ0054) — Fire station (NQ0055) — Former fire training ground (NQ0105) — Former fire training ground (NQ0106) — Former fire training ground (NQ0107) — Pad Brahman — Disused Runway 13/31 — Fuel Farm 1 (NQ0052); and — Fuel Farm 2 (NQ0099).

— Firefighting activities for incidents where fuel ignition was a potential: — Runways 01/19 and 07/25.

— Routine operation of fire deluge systems: — 5 AVN Regiment Hangars (Buildings 236 and 295).

— Equipment testing and tank washing/purging: — 5 AVN wash point.


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— Production of foam as part of Open Day demonstrations: — Former Cadet training area — Ingham Road sports fields.

There are also likely to be background (i.e. off-Base) sources of PFAS within the IA and these include the following: — Woodlands Fire Station where PFAS handling and fire training may occur. — Bohle Fire Station where PFAS handling and fire training may occur. — Queensland Fire and Emergency Services Northern Region Mechanical Workshop, located

at 38–40 Auscan Crescent, Garbutt, where fire training and PFAS handling may occur. — Mount St John WTP where treatment of PFAS contaminated water may have occurred. — Rowes Bay Golf Club (refer discussion below). — The former Bohle WTP (that was operational prior to commissioning of the Mount St John

WTP). Up-gradient PFAS was detected in Louisa and Peewee Creeks and the Bohle River in the DSI (WSP 2018a), indicating the potential presence of off-Base PFAS sources in Garbutt and Bohle. However, the relative contribution of PFAS from these background sources is considered minor when compared with the contribution from the Base.

POTENTIALLY IMPACTED MEDIA

Soil, sediment, surface water, groundwater and biota.

CONTAMINANTS OF CONCERN

PFAS contaminants of concern comprise the following, which correspond to analytes for which there are criteria under the Heads of Environmental Protection Authorities (HEPA) PFAS National Environmental Management Plan (PFAS NEMP) (HEPA 2018) (Section 6.2): — PFOS — PFOA; and — PFHxS. Other PFAS analytes are to be included in the analysis suite from the laboratory based on DoD Guideline E (DoD 2018).

MIGRATION PATHWAYS

Potential migration pathways for PFAS once discharged to the environment include: — discharge/spill of AFFF onto ground, infiltration into soil and sorption to soil and organic

matter — discharge or spill of AFFF into drainage channels and flowing off-Base into the

catchments of Mundy Creek, Louisa Creek, Peewee Creek, Three Mile Creek and The Common

— pumping of impacted surface water from on-Base catchments into the Louisa Creek and Three Mile Creek catchments (occurring during the discharge sampling in March 2018 but not at the time of the DSI or Seasonal Monitoring Report 1)

— sorption of PFAS onto sediment particles — physical transport of sediments off-Base as suspended solids (due to heavy rainfall or

maintenance works in drains) in surface water into the Mundy Creek, Louisa Creek, Peewee Creek, Three Mile Creek and the Town Common catchments

— desorption of PFAS from impacted sediments into surface waters of Mundy Creek, Louisa Creek, Three Mile Creek and the Town Common

— leaching of PFAS from soils into surface water runoff or vadose zone waters and discharge into drainage channels

— vertical migration of PFAS leached from the vadose zone by infiltrating rain/surface water to shallow groundwater

— lateral migration of dissolved PFAS with groundwater flow


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— sorption of PFAS to soil beneath the groundwater table during migration of groundwater – sorbed PFAS will leach with changing groundwater conditions, acting as a secondary source

— infiltration of impacted surface water from water bodies under losing conditions (when surface water levels are higher than the groundwater table). This is inferred to occur in the Town Common, Three Mile Creek and the upper and middle reaches of Mundy Creek. This may lead to groundwater impacts with no direct groundwater connection to groundwater impact at the primary source

— discharge of impacted groundwater to on-Base drains and the lower reaches of Mundy Creek

— PFAS ingestion by aquatic organisms and bio-magnification in the food web, including the human consumption of fish/seafood.

POTENTIAL SENSITIVE RECEPTORS

Based on the Base setting, sensitive receptors potentially include: — on-Base personnel and temporary residents accessing exposed areas of the Base — on-Base and off-Base sub-surface maintenance or construction workers — on-Base child care or kindergarten attendees — aquatic ecosystems of the Town Common, Louisa Creek, Peewee Creek, Three Mile

Creek, Mundy Creek and the Bohle River — terrestrial ecosystems connected with the above aquatic ecosystems (particularly the Town

Common) through the food web — consumers of recreational fishing catch and aquatic organisms (fish, crustaceans,

molluscs) collected for consumption from the Town Common, Three Mile Creek, Mundy Creek, Bohle River, Halifax Bay and Rowes Bay

— off-Base residential users of groundwater extracted from private groundwater bores for domestic (potable and non-potable) purposes.

POTENTIAL EXPOSURE PATHWAYS

Potential exposure pathways include: — ecological receptors in direct contact with PFAS impacted soil, surface water and

groundwater. Particularly in the on-Base wetlands, receiving wetlands of the Town Common and Louisa Creek, Peewee Creek, Three Mile Creek and Mundy Creek

— biomagnification through the food web — incidental ingestion of on-Base PFAS impacted soil — direct contact (dermal contact and incidental ingestion) with PFAS impacted surface

waters and sediments through recreational use (swimming, fishing, crabbing) — ingestion of PFAS impacted aquatic organisms (fish, crustaceans, molluscs) through

consumption of recreational fishing catch — incidental ingestion or aerosol inhalation of PFAS impacted extracted groundwater from

private residential bores through irrigation misting or sprinkler play — consumption of domestically grown plants or animals which are PFAS impacted through

irrigation and/or watering with PFAS impacted extracted groundwater from private residential bores.

Note that inhalation of PFAS vapour is not considered to be a potentially complete exposure pathway given that on the basis of current information, PFAS analytes are non-volatile.

The exposure pathway for human consumption of terrestrial biota within the Town Common is expected to be incomplete given the National Park status and the prohibition of collection of terrestrial biota for consumption. Defence liaison with Indigenous communities that reside in the IA established that consumption of ‘bush tucker’ does not occur within the IA. The HHRA (WSP 2018b) did not identify any unacceptable risks associated with the consumption of terrestrial flora and fauna.

WSP recognise that there is a complete exposure pathway for non-domestic terrestrial biota via mechanisms including consumption of water and aquatic biota. The assessment of these terrestrial receptors has been considered as a component of the ERA (WSP 2019a).


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5 APPROACH AND METHODOLOGY 5.1 APPROACH AND SAMPLING RATIONALE WSP’s proposed approach to deliver the DSI (WSP 2018a) was detailed in the SAQP (WSP 2017 – 2270642A-CLM-REP-001 Rev4) which was approved by the Technical Advisor and Defence. The assessment of receiving water environmental values as set out in the Queensland Environmental Protection (Water) Policy (2009) has been used to develop the sampling rationale for the surface water and groundwater aspects of the DSI (WSP 2018a) and the DSI Addendum.

5.1.1 TECHNICAL AND REGULATORY FRAMEWORK

The DSI (WSP 2018a) and Seasonal Monitoring Report 1 have been undertaken with reference to the following guidelines:

— Australian Standard AS4482.1 2005, Guide to the investigation and sampling of sites with potentially contaminated soil – Part 1: Non-volatile and semi-volatile compounds.

— Australian Standard AS4482.2 1999, Guide to the sampling and investigation of potentially contaminated soil – Part 2: Volatile substances.

— Australian Standard AS5667.1 1998, Water quality – sampling. Part 1: Guidance on the design of sampling programs, sampling techniques and the preservation and handling of samples.

— Department of Defence 2016a, PFAS Guidance Document A: PFAS Source and Receptor Identification Framework, November 2016.

— Department of Defence 2017b, PFAS Guidance Document D: Non PFAS Analysis of Other Chemicals of Potential Concern, February 2017.

— Department of Defence 2018, PFAS Guidance Document E: Standard PFAS Analytical Suite for Detailed Site Investigations, March 2018.

— Department of Defence 2012, Defence Contamination Directive #7, Naming Convention – Surface Water, Groundwater Bore, Soil and Sediment Sampling Identification, July 2012.

— Department of Defence 2017a, Defence Contamination Directive #8 (Amendment 1) Interim Screening Criteria, Defence Project Guidance for Per- and Poly-Fluoroalkyl Substances (PFAS), September 2016.

— Department of Environment and Energy (DoEE) 2016, Draft Commonwealth Environmental Management Guidance on Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA), October 2016.

— Department of Health (DoH) 2017, Health Based Guidance Values for PFAS for use in Site Investigations in Australia.

— enHealth 2016, enHealth Statement: Interim National Guidance on Human Health Reference Values for Per- and Poly-Fluoroalkyl Substances for Use in Site Investigations in Australia, June 2016.

— HEPA 2018, PFAS National Environmental Management Plan, January 2018. — National Environment Protection Council (NEPC) 1999 Amended, National Environment Protection (Assessment of

Site Contamination) Amendment Measure 2013 (No. 1). — National Uniform Drillers Licencing Committee (NUDLC) 2012, Minimum Construction Requirements for Water

Bores in Australia, Third Edition. — NSW Environment Protection Authority (EPA) 2016, Guidance Note: Designing Sampling Programs for Sites

Potentially Contaminated by PFAS, November 2016. — NSW Office of Environment and Heritage (OEH) 2017, Draft PFAS Screening Criteria (May 2017), Contaminants

and Risk, Environment Protection Science Branch, May 2017. — Queensland Department of Environment and Heritage Protection (EHP), July 2018, Queensland Auditor Handbook

for Contaminated Land. Module 6: Content requirements for contaminated land investigation documents, a certifications and audit reports.

— Queensland Environmental Protection Act 1994. — Queensland Environmental Protection Regulation 2008. — Queensland Environmental Protection (Water) Policy (2009). — Queensland EHP 2009a, Monitoring and Sampling Manual, Version 2, July 2013.


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— Queensland EHP 2009b, Queensland Water Quality Guidelines (2013a).

5.1.2 ENVIRONMENTAL VALUES

Prescribed environmental values for receiving waters from the Base that lie within the area subject to the Ross River Basin and Magnetic Island Environmental Values and Water Quality Objectives (EHP 2013) have been reproduced in Table 5.1 and are consistent with the DSI (WSP 2018a).

Furthermore, under the Environmental Protection Act 1994, general obligations associated with public safety and amenity (e.g. vapour intrusion, direct contact in a utility trench) also potentially apply where applicable and have been presented in Table 5.1.

Table 5.1 Prescribed water environmental values within the IA

PRESCRIBED ENVIRONMENTAL VALUE

GR

OU

ND

WA

TER

S

TOW

N C

OM

MO

N

FRES

H &

EST

UA

RIN

E W

ATE

RS

BO

HLE

RIV

ER

ESTU

AR

INE

WA

TER

S

LOU

ISA

CR

EEK

FR

ESH

& E

STU

AR

INE

WA

TER

S

RO

SS C

REE

K F

RES

H

WA

TER

S

PALL

AR

END

A F

RES

H

& E

STU

AR

INE

WA

TER

S

Aquatic ecosystems

Irrigation

Farm supply/use

Stock water

Aquaculture

Human consumer

(2)

Primary recreation

Secondary recreation

(1)

Visual recreation

Drinking water

Industrial use

Cultural & spiritual values

Public amenity & safety

Notes:


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(1) Fresh water only (2) Estuarine water only

Within the NEPM source-pathway-receptor framework, the environmental values above have only been assessed where the exposure pathway can be reasonably demonstrated to be complete.

5.1.2.1 SHALLOW SANDY FRESHWATER AQUIFER

Utilising the matrix in Table 5.1, prescribed environmental values for the shallow sandy freshwater aquifer in the north-eastern portion of the IA include the following:

— aquatic ecosystem — irrigation — farm supply/use — stock water

— aquaculture — human consumer — primary recreation — secondary recreation

— visual recreation — drinking water — cultural and spiritual values; and — public safety and amenity.

The averaged total dissolved solids (TDS) (878 mg/L) of the shallow sandy freshwater aquifer proximate to Cleveland Bay (WSP 2018a) have been compared against literature limits on water quality for the potential environmental values and presented in Table 5.2.

Table 5.2 Sandy freshwater aquifer environmental values

ITEM TDS RANGE (mg/L) DETAIL

Aquatic ecosystems Not applicable Not applicable The salinity of the aquifer is a natural feature and so

groundwater is suitable for discharge to aquatic ecosystems.

Irrigation The shallow freshwater aquifer may be suitable for

irrigation of most plant species except those sensitive to salinity.

Yield from this aquifer is unlikely to be a limitation to this environmental value in a built-up landscape where there are limited extractors.

— Sensitive crops <420 (1) (4)

— Moderately sensitive crops <845 (1) (4)

— Moderately tolerant crops <1,885 (1) (4)

— Tolerant crops <3,800 (1) (4)

— Very tolerant crops <5,265 (1) (4)

— Generally too saline >5,265 (1) (4)

Farm supply/use Hardness used

as criteria not applicable The shallow freshwater aquifer may be suitable for

farm supply/use, although properties within the IA are on reticulated potable town water and so non-potable domestic use of groundwater is expected to have low likelihood.



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Stock water The shallow freshwater aquifer may be suitable for

stock water purposes, although properties within the IA are on reticulated potable town water and so stock water use of groundwater is expected to be likely limited to poultry. Extraction of groundwater in the Town Common for cattle is no longer undertaken.


— Beef cattle <4,000 (1)

— Dairy cattle <2,400 (1)

— Sheep, horses & pigs <4,000 (1)

— Poultry <2,000 (1)


Aquaculture Not applicable Not applicable The shallow freshwater aquifer may be suitable for

aquaculture, although there are no known aquaculture extractors within the IA.

Yield from this aquifer may be a limitation to this environmental value given the expected limited extent of the shallow freshwater aquifer adjacent to Cleveland Bay.

Human consumer TDS not

applicable TDS not

applicable This environmental value is applicable and may include potential exposure where contaminants bioaccumulate in biota that are consumed by the community and applies where groundwater discharges into waterways (EHP, 2013) and so dilution is expected to be a consideration.

Primary recreation <1,200 (1) This environmental value is applicable to incidental

exposure during recreational activities such as swimming and applies where groundwater discharges into waterways (EHP, 2013) and so dilution is expected to be a consideration.

Secondary recreation

TDS not applicable

TDS not applicable

This environmental value is applicable to incidental exposure during recreational activities such as boating and applies where groundwater discharges into waterways (EHP, 2013) and so dilution is expected to be a consideration.

Visual recreation TDS not

applicable TDS not

applicable This environmental value is applicable to non-contact exposure (e.g. sheen, odour) and applies where groundwater discharges into waterways (EHP, 2013) and so dilution is expected to be a consideration.


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Drinking water <600 (2) (3) The shallow freshwater aquifer is not considered

suitable for ingestion given the total dissolved solids. Residences within the IA are on municipal water supply and unlikely to be using bore water for regular drinking. This is supported by the water use survey, which identified no drinking water use in the IA. However, parts of the aquifer in Rowes Bay and Pallarenda may have potable water quality, therefore the use of bore water for domestic water and drinking cannot be discounted.

Cultural and spiritual values

TDS not applicable

TDS not applicable

This environmental value is applicable and may include potential exposure at indigenous cultural sites and/or impacts on totemic species.

Public amenity and safety

TDS not applicable

TDS not applicable

This environmental value is applicable and may include potential exposure pathways such as direct contact in a utility trench.

Notes:

(1) ANZECC & ARMCANZ 2000, Australian and New Zealand Water Quality Guidelines for Fresh and Marine Waters (2) NHMRC & NRMMC 2011, Australian Drinking Water Guidelines 6 (3) Aesthetic criteria (NHMRC & NRMMC 2011) (4) TDS = 0.65 x EC (ANZECC & ARMCANZ 2000)

mg/L = milligrams per litre

Utilising a risk assessment framework outlined in Establishing Draft Environmental Values, Management Goals and Water Quality Objectives (EHP 2013), the suitability of the water for its use for several prescribed environmental values can be integral to the applicability of the environmental value. On this basis, TDS may not be the only criteria, as yield can also determine if criteria are applicable. Considering the physiochemical limitation (TDS) and the physical limitation (yield) of a sandy aquifer, applicable groundwater environmental values for the shallow freshwater sandy aquifer are:

— aquatic ecosystem (groundwater discharged to waterways) — irrigation (non-potable domestic irrigation) — farm supply/use (non-potable domestic use) — stock water (poultry most probable use) — human consumer (groundwater discharged to waterways) — primary recreation (groundwater discharged to waterways) — secondary recreation (groundwater discharged to waterways) — visual recreation (groundwater discharged to waterways) — cultural and spiritual values (groundwater discharged to waterways); and — public amenity and safety.

The environmental values considered are consistent with the DSI (WSP 2018a).

Prescribed environmental values for drinking water for groundwater from the sandy freshwater aquifer is not considered to be a potentially complete exposure pathway for this aquifer.


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5.1.2.2 SHALLOW CLAYEY SALINE AQUIFER

Utilising the matrix in Table 5.1, potential environmental values for the shallow clayey saline aquifer that extends across most of the Investigation Area include the following:

— aquatic ecosystem — irrigation — farm supply/use — stock water

— aquaculture — human consumer — primary recreation — secondary recreation

— visual recreation — drinking water — cultural and spiritual values; and — public safety and amenity.

The averaged TDS (20,420 mg/L) of the shallow saline clayey aquifer that dominates the IA (WSP 2018a) has been compared against literature limits on water quality for the prescribed environmental values and presented in Table 5.3.

Table 5.3 Clayey saline aquifer environmental values


Aquatic ecosystems Not applicable Not applicable The salinity of the aquifer is a natural feature and so

groundwater is suitable for discharge to aquatic ecosystems.

Irrigation With the potential exception of areas proximate for

freshwater waterways, the shallow saline aquifer is unlikely to be suitable for irrigation of crops based on the total dissolved solids.

Yield from this aquifer is likely to be a limitation to this environmental value given the clayey lithology.

— Sensitive crops <420 (1) (4)

— Moderately sensitive crops <845 (1) (4)

— Moderately tolerant crops <1,885 (1) (4)

— Tolerant crops <3,800 (1) (4)

— Very tolerant crops <5,265 (1) (4)

— Generally too saline >5,265 (1) (4)

Farm supply/use Hardness used

as criteria n/a The shallow saline aquifer is unlikely to be suitable

for farm supply/use due to likely fouling and corrosion issues.

Yield from this aquifer is likely to be a limitation to this environmental value given the clayey lithology.

Stock water The shallow saline aquifer is unlikely to be suitable

for stock water uses due to salinity.


— Dairy cattle <2,400 (1)

— Sheep, horses & pigs <4,000 (1)

— Poultry <2,000 (1)


Aquaculture TDS not

applicable TDS not

applicable The shallow saline aquifer is unlikely to be suitable for aquaculture uses due to salinity.


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applicable TDS not

applicable This environmental value is applicable and may include potential exposure where contaminants bioaccumulate in biota that are consumed by the community and applies where groundwater discharges into waterways (EHP 2013) and so dilution is expected to be a consideration.

Primary recreation <1,000 (1) This environmental value is still applicable to

incidental exposure during recreational activities such as swimming and applies where groundwater discharges into waterways (EHP 2013) and so dilution is expected to be a consideration.

Secondary recreation TDS not

applicable TDS not

applicable This environmental value is applicable to incidental exposure during recreational activities such as boating and applies where groundwater discharges into waterways (EHP 2013) and so dilution is expected to be a consideration.


applicable TDS not

applicable This environmental value is applicable to non-contact exposure (e.g. sheen, odour) and applies where groundwater discharges into waterways (EHP 2013) and so dilution is expected to be a consideration.

Drinking water <600 (2) (3) The shallow saline aquifer is not considered suitable

for ingestion given the TDS. Residences within the IA are on municipal water supply and unlikely to be using bore water for regular drinking. This is supported by the water use survey, which identified no drinking water use in the IA.


TDS not applicable

TDS not applicable



TDS not applicable

TDS not applicable


Notes:

(1) ANZECC & ARMCANZ 2000, Australian and New Zealand Water Quality Guidelines for Fresh and Marine Waters (2) NHMRC & NRMMC 2011, Australian Drinking Water Guidelines 6 (3) Aesthetic criteria (NHMRC & NRMMC 2011) (4) TDS = 0.65 x EC (ANZECC & ARMCANZ 2000)



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Utilising a risk assessment framework outlined in Establishing Draft Environmental Values, Management Goals and Water Quality Objectives (EHP 2013), the suitability of the water for its use for several prescribed environmental values can be integral to the applicability of the environmental value. On this basis, TDS may not be the only criteria, as yield can also determine if criteria are applicable. For example, the definition for ‘irrigation’ states:

— Suitability of water supply for irrigation, for example, irrigation of crops, pastures, parks, gardens and recreational areas.

In a low yielding aquifer, the supply of water cannot be sustained. Thus, several environmental values are not applicable for the shallow saline clayey aquifer based on expected yield alone. Groundwater extraction from the shallow saline clayey aquifer that dominates the IA is also limited in extent given that properties are connected to the mains reticulated water supply. Considering the physiochemical limitation (TDS) and the physical limitation (yield) of a clayey aquifer, applicable groundwater environmental values for the shallow saline clayey aquifer are:

— aquatic ecosystem (groundwater discharged to waterways) — human consumer (groundwater discharged to waterways) — primary recreation (groundwater discharged to waterways) — secondary recreation (groundwater discharged to waterways) — visual recreation (groundwater discharged to waterways) — cultural and spiritual values (groundwater discharged to waterways); and — public amenity and safety.

The environmental values considered are consistent with the DSI (WSP 2018a).

Prescribed environmental values for drinking water, irrigation, stock water and farm supply/use for groundwater from the clayey saline aquifer are not considered to be a potentially complete exposure pathway for this aquifer.

5.1.2.3 SURFACE WATER

Utilising the matrix in Table 5.1, prescribed environmental values for the surface water from the Base in waterways surrounding the Base may include the following:

— aquatic ecosystem — human consumer — primary recreation

— secondary recreation — visual recreation

— cultural and spiritual values; and

— public safety and amenity.

Table 5.4 Surface water environmental values


Aquatic ecosystems Not applicable Not applicable The salinity of surface water run-off is likely to be

comparable to natural levels given contact with land.


applicable TDS not

applicable This environmental value is applicable and may include potential exposure where contaminants bioaccumulate in biota that are consumed by the community.

Primary recreation <1,200 (1) This environmental value is applicable to incidental

exposure during recreational activities such as swimming. However, this is considered unlikely in areas where crocodiles and/or Irukandji jellyfish are endemic and so only applies to freshwater areas of the Bohle River.


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Secondary recreation TDS not

applicable TDS not

applicable This environmental value is applicable to incidental exposure during recreational activities such as boating.


applicable TDS not

applicable This environmental value is applicable to non-contact exposure (e.g. sheen, odour).


TDS not applicable

TDS not applicable



TDS not applicable

TDS not applicable


Notes:

(1) ANZECC & ARMCANZ 2000, Australian and New Zealand Water Quality Guidelines for Fresh and Marine Waters


The prescribed environmental values of receiving waterways around the Base will be the adopted environmental values for the Seasonal Monitoring Report 1, and are consistent with the DSI (WSP 2018a).

5.1.3 RATIONALE

The rationale for sampling and field observations within the IA are detailed below. The rationale is generally consistent with that selected for the DSI (WSP 2018a).

Table 5.5 Sampling rationale

TASK FIELD ACTIVITIES APPROACH AND RATIONALE

Surface water sampling

Collection of surface water samples for the purpose of characterising drainage areas that may carry PFAS solution from secondary sources, particularly following a wet weather event.

The sample design was for surface water samples to be collected up-gradient (i.e. coming onto Base), from source areas and down-gradient of source areas.

Unless a PFAS product was in use during or immediately prior to sample collection, surface water samples will help demonstrate the on-going mobilisation of PFAS into surface water from secondary sources at the Base. These may include releases from sediments, soil and groundwater.

Surface water samples were collected where ponded water was present. Whilst the proposition was to collect surface water samples collocated with sediment samples, where a location was dry, the sediment sample was the only sample collected.


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TASK FIELD ACTIVITIES APPROACH AND RATIONALE

Sediment sampling Collection of sediment samples for the purpose of characterising drainage areas that may have carried PFAS solution, particularly following a wet weather event.

The sample design was for sediment samples to be collected up-gradient (i.e. coming onto Base), from source areas and down-gradient of source areas.

Sediment samples help demonstrate the on-going mobilisation of PFAS into surface water as a secondary source at the Base.

Where safe to do so, sediment samples were collected collocated with surface water samples. Safety risks (such as crocodiles and confined spaces) were identified and managed through the project Health, Safety and Environment Management Plan (HESP).

Soil sampling Collection of soil samples to further characterise the Ingham Road Playing fields, delineate near-surface PFAS soil impact between the Base and residences within Garbutt, and to investigate potential soil impacts from residents irrigating with PFAS-impacted groundwater.

Near surface soil samples were collected on a grid pattern at the Ingham Road Playing fields where the drill rig was not able to access during the DSI investigations (WSP 2018b).

Near surface samples were collected outside the eastern Base boundary between the Base and residences in Garbutt.

Shallow soil samples were collected from selected properties that had been identified to be irrigating lawns, vegetable gardens and fruit trees with PFAS-impacted groundwater.

Groundwater sampling

Collection of groundwater samples for laboratory analysis from all groundwater monitoring wells that were previously sampled as part of the DSI (WSP 2018a).

All groundwater monitoring wells that had been sampled for PFAS during the DSI (WSP 2018a), were sampled again as part of this Seasonal Monitoring Report 1. Samples were analysed for the 28 PFAS suite, with wells that returned dry season results of <0.10 µg/L selected for the ultra-trace 28 PFAS suite.

Biota sampling Collection of fruit and vegetable samples to investigate potential plant impacts as a result of irrigation with PFAS-impacted groundwater.

Available fruits and vegetables were collected from selected properties that were identified to irrigate gardens and fruit trees with PFAS-impacted groundwater. Mature fruits and vegetables were selected for sampling.


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5.2 METHODOLOGY The wet season discharge water sampling event was conducted 1–5 March 2018 and involved sampling four base discharge locations (SW102, SW123, SW131 and SW132) every day for five days.

The wet season GME investigation was conducted between 9–20 April 2018 and mirrored the sampling (locations and methodology undertaken during the DSI (WSP 2018a), undertaken from August 2017 to January 2019, to facilitate a direct comparison of ‘dry’ and ‘wet’ weather analytical results.

On-Base soil sampling was conducted on 17 April 2018 and 25 June 2018. Off-base soil sampling was undertaken on 25–27 June 2018, 3 August 2018 and 28 September 2018. The additional soil sampling was undertaken to address data gaps identified in the DSI (WSP 2018a).

Biota (fruit and vegetables) sampling was conducted off-base on 3 August 2018 and 28 September 2018. The sampling was undertaken to inform the HHRA on potential exposure pathways identified after the completion of the DSI (WSP 2018a).

No additional installation of groundwater monitoring wells was conducted as part of the Seasonal Monitoring Report 1.

5.2.1 SOIL

All soils samples collected for the Seasonal Monitoring Report 1 were taken from within 0.3 m of the surface using a hand trowel. Therefore, no service clearance or exploded/unexploded ordnance clearance was required. The soil assessment methodology is summarised in Table 5.6.

Table 5.6 Soil assessment methodology

ACTIVITY DETAILS

Soil sample collection

Soil samples were collected at near the surface (0–0.3 m) on-Base and off-Base. Samples were collected using a stainless steel hand trowel. Samples were collected directly from the hand-trowel with single-use disposable gloves and placed into laboratory-supplied glass jars without Teflon lids.

Sample containers were placed into iced, insulated containers and transported to the laboratory under chain of custody (COC) protocols.

Soil logging Soil descriptions were recorded on based on the Unified Soil Classification System (USCS) and Australian Standard (AS) 4482.1-1997.

Decontamination The hand trowel was rinsed in a three-stage procedure using certified PFAS-free detergent, Liquinox®.

Waste All excavated soil was used as sample and no waste was generated.

Soil bore locations All soil bore locations were measured using a Magellan handheld global positioning system (GPS) with coordinates recorded in Map Grid of Australia (MGA1984) datum.


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5.2.2 GROUNDWATER

The groundwater assessment methodology is summarised in Table 5.7.

Table 5.7 Groundwater assessment methodology

ACTIVITY DETAILS

Well gauging All sampled on-Base and off-Base monitoring wells were gauged using a decontaminated oil/water interface probe to detect SWL and possible non aqueous phase liquids (NAPLs). Gauging data is presented in Table 1 in Appendix B.

Groundwater sampling

Groundwater samples were collected from all on-and-off-Base monitoring wells using PFAS-free high-density polyethylene (HDPE) Hydrasleeves™ with samples decanted into clean laboratory-supplied containers. All bottles were labelled clearly with the well identification and the sampling date.

The methodology for sampling with Hydrasleeves™ is as follows:

— The Hydrasleeve™ (with anchor attached) was affixed to nylon-twine and lowered to the base of the monitoring well.

— The Hydrasleeve™ was then retrieved, drawing with it a volume of groundwater. — The groundwater was transferred directly from the Hydrasleeve™ into the laboratory-

supplied bottles. — A number of deploys and retrievals of the Hydrasleeve™ was necessary to attain sufficient

groundwater to fulfil the minimum volume requirement for all analysis at locations where extended suite or duplicates and triplicates were collected. The PFAS sample was always collected from the first deploy.

— Following sealing of the sample bottles, the bottles were transferred into an insulated container with free ice present and delivered directly to the laboratory under COC protocols for analysis.

Field hydrochemical parameters

A calibrated water quality (WQ) meter was used to collect hydrochemical parameters. WQ measurements were recorded in-situ where the standing water level permitted, or ex-situ where the standing water level was lower than the length of the water quality meter cable. Water quality measurements were recorded following sample collection and observations were recorded once quality parameters stabilised.

Decontamination Single-use disposable gloves were used to collect each groundwater sample. A dedicated HydrasleeveTM was used at each monitoring well. Decontamination of the HydrasleeveTM

anchors, interface probe and water quality meter was undertaken by three-stage wash and rinse using certified PFAS-free detergent (Liquinox®), mains water and demineralised water.

Waste Waste groundwater was generated during sampling and from the decontamination of field equipment. This waste water was stored in a 1 m3 intermediate bulk container for off-Base disposal in accordance with the Environmental Management Plan (EMP) and the Defence-issued Environmental Clearance Certificate (ECC).


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5.2.3 SURFACE WATER

The surface water assessment methodology is summarised in Table 5.8.

Table 5.8 Surface water assessment methodology

ACTIVITY DETAILS

Surface water sampling

Surface water samples were collected from the same on-and-off-Base locations sampled in the DSI (WSP 2018a). The locations were identified using GPS coordinates and a hand-held GPS field meter. Water samples were collected from ground surface, open drains, channels, creeks and the Bohle River.

Samples were collected using a telescopic pole sampler with stainless steel scoop. The samples were collected from approximately 100 mm below the water surface where water depth allowed sample collection without disturbance of sediments. The sample was transferred to laboratory supplied containers with no identifiable headspace and the cap was immediately applied. The samples were placed into an insulated container with free ice present and transported to the laboratory under COC protocols.

Due to the potential health and safety risks associated with crocodiles, a boat was required at some locations.

Field hydrochemical parameters

A calibrated WQ meter was used to measure hydrochemical parameters ex-situ. Surface water was collected using a telescopic pole sampler with stainless steel scoop and transferred into a HDPE PFAS sample bottle with the neck removed to allow the WQ meter to be placed within the container. Readings were recorded after parameter equilibration. General observations regarding the surface water appearance, quality and flow were documented.

Decontamination Single-use disposable nitrile gloves were used to collect each surface water sample. Decontamination of the sampling scoop and WQ meter probes was conducted prior to sampling from each location, using three-stage washing with PFAS-free detergent (Liquinox®), mains water and demineralised water.


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5.2.4 SEDIMENT SAMPLING Table 5.9 Sediment sampling methodology

ACTIVITY DETAILS

Sediment sampling Sediment samples were collected from open drains and channels on- and off-Base and creeks and the Bohle River off-Base. All sediment sampling locations were co-located with a surface water sampling location where surface water was present.

Sediment samples collected from areas accessible by land. Samples were collected using either a telescopic pole sampler with stainless steel scoop or a hand-trowel, and were scraped from the surface of the sediments to a maximum depth of approximately 0.1 mbgl.

Where sediment samples were collected from the Bohle River, a stainless steel ‘bomb sampler’ was deployed into the water column to facilitate sample collection.

Samples were collected directly from the stainless steel scoop, hand-trowel or bomb sampler and were transferred to laboratory supplied glass jars with Teflon-free lids. The samples were placed into an insulated container with free ice present and transported to the laboratory under COC protocols.

Sediment logging Sediment samples were logged generally in accordance with the UCSC.

Decontamination Single-use disposable nitrile gloves were used to collect each sediment sample. Decontamination of the stainless steel scoop, hand-trowel and bomb sampler was conducted prior to sampling from each location, using three-stage washing with PFAS-free detergent (Liquinox®), mains water and demineralised water.

5.2.5 RESIDENTIAL BORE SAMPLING

The specific methodology for the collection of groundwater from residential bores was dependent on the specific use and infrastructure present at each bore. The residential water bore sampling methodologies are summarised in Table 5.10.

Table 5.10 Residential bore sampling methodology

ACTIVITY DETAILS

Bore sampling Where possible, water samples were collected directly from the point of use, being a tap or pipe outlet. To collect the “first flush” of water sample, the laboratory supplied containers were placed directly beneath the outlet and the tap slowly opened whilst the pump was running. The sample bottle was filled with no identifiable headspace remaining and the cap immediately applied. The samples were then placed into an insulated container with free-ice present.

Where no tap or pipe outlet convenient for sampling was present, samples were collected directly from the bore using a Hydrasleeve™, using the groundwater sampling methodology described in Table 5.7.

Field water quality parameters

Water quality parameters of a subset sample collected from the bore were measured using a calibrated WQ meter. General observations of water colour, odour and turbidity were recorded at the time of sampling.

Decontamination Single-use disposable nitrile gloves were used to collect each water sample. No sampling equipment was reused in the sampling of the residential water bores; therefore, decontamination was not necessary.


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5.2.1 RESIDENTIAL SWIMMING POOL SAMPLING

One sample was collected from the full swimming pool at a private residence in Pallarenda. The sampling location has not been shown on any figures to protect the resident’s privacy.

The swimming pool sampling methodology is summarised in Table 5.11.

Table 5.11 Swimming pool sampling methodology

ACTIVITY DETAILS

Water sampling The water sample was collected directly into the laboratory supplied container, which was held by hand at approximately 100 mm below the water surface and inverted to allow water ingress. The sample bottle was filled with no identifiable headspace remaining and the cap immediately applied.

Sample preparation Following collection, the sample was placed into an insulated container with free-ice present and delivered to the laboratory for analysis.

Decontamination Single-use disposable nitrile gloves were used to collect the water biota sample. No sampling equipment was reused in the sampling of the swimming pool; therefore, decontamination was not necessary.

5.2.2 RESIDENTIAL BIOTA SAMPLING

Biota sampling was limited to the collection of fruit and vegetables from resident’s gardens. Biota sampling locations have not been shown on any figures to protect resident’s privacy.

The fruit and vegetable sampling methodology is summarised in Table 5.12.

Table 5.12 Biota sampling methodology

ACTIVITY DETAILS

Fruits and vegetables Fruit and vegetables were sampled by hand by directly removing the sample from the tree or ground.

Sample preparation Following collection, all samples (whole) were placed individually in appropriate/approved storage containers. Samples were then placed into an insulated container with free-ice present and delivered to the laboratory for analysis.

Decontamination Single-use disposable nitrile gloves were used to collect and prepare each biota sample.


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5.3 LABORATORY ANALYSIS Primary analysis for the investigation was undertaken by ALS Smithfield, NSW for the PFAS suite of analytes. ALS methods for analysis were certified by NATA.

Eurofins MGT conducted the secondary (‘check’) analysis for the DSI. Eurofins MGT is NATA accredited for all sediment and water analyses undertaken.

All sediment, soil, surface water and groundwater and biota samples submitted for analysis were analysed for the 28-analyte PFAS suite (DoD 2018), presented in Section 1.5.3. Selected samples were also analysed for TOP assay. In order to assist hydrogeological conceptualisation, groundwater samples were also analysed for:

— Major cations – calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na); and — Major anions – chloride (Cl), sulfate (SO4), hydroxide alkalinity (OH), bicarbonate alkalinity (HCO3) and carbonate

alkalinity (CO3).

Selected on-Base groundwater samples were also analysed for a comprehensive suite of water quality parameters as follows:

— Nutrients – nitrogen, nitrate, nitrite, ammonia, total kjedahl nitrogen, reactive phosphorus, phosphorus — General parameters – BOD, COD, TDS, TSS — Metals – aluminium, iron, ferrous iron, manganese, phosphorus; and — Fluoride.

In order to gain an understanding of certain parameters that may influence PFAS behaviours in sediments, selected sediment samples collected from on-Base were also analysed for the following:

— TOC — PSD — Exchangeable calcium, magnesium, potassium and sodium — pH; and — Iron.


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6 ASSESSMENT CRITERIA

6.1 OVERVIEW Assessment criteria, also known as Investigation levels (ILs), have been selected in accordance with NEPC (2013) and Defence requirements with Australian endorsed criteria referenced and presented in the following sections. The assessment criteria selected for the Seasonal Monitoring Report 1 are consistent with those selected for the DSI (WSP 2018a).

In the event that an analyte was reported in excess of the LOR and no Australian endorsed and/or defensible criteria exists, an IL could be sourced from a guidance authored by a reputable international agency utilising methodologies applicable to the derivation of criteria in Australia. Agencies that may be considered include those in North America (United States and Canada) and Europe (United Kingdom and the Netherlands).

It is noted that additional human health guideline values had become available since the commencement of the project (HEPA 2018, DoH 2017) and those values have been incorporated into both the DSI (WSP 2018a) and this Seasonal Monitoring Report 1.

6.2 SOIL ASSESSMENT CRITERIA Soil ILs have been selected from publications in accordance with the methodology in NEPC (2013) and the current most sensitive land use adjacent to the sample collection point. As a result, soil ILs for which criteria have been established are presented in Table 6.1, adopted from the following guidelines:

— HEPA 2018, PFAS National Environmental Management Plan, January 2018. Human Health-based guidance values HBGV):

— Residential with garden/accessible soil — Residential with minimal opportunities for soil access — Public open space — Industrial/commercial areas.

— HEPA 2018, PFAS National Environmental Management Plan, January 2018. Interim soil – ecological guidelines:

— Public open space – ecological direct exposure — Residential – ecological indirect exposure — Industrial/commercial – ecological indirect exposure.

WSP acknowledge that the criteria for residential land uses has been developed to include an apportionment to the uptake by occupants through the consumption of homegrown produce both on- and off-Base. On the basis of the DSI (WSP 2018a), this exposure pathway is considered incomplete for the domestic area on-Base; however, for the kindergarten, and immediately surrounding areas the residential land use criteria for PFAS has been applied as a protective (and conservative) measure for soil screening purposes.

6.3 SEDIMENT ASSESSMENT CRITERIA Specific guidelines for PFAS contamination in sediments are not available. Sediment PFAS results in conjunction with biota PFAS results will be used in the HHRA and ERA to establish the potential risk posed to human and ecological receptors by PFAS in the sediment via direct contact with and/or incidental ingestion (where relevant).


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6.4 WATER ASSESSMENT CRITERIA Water ILs have been selected from publications in accordance with the methodology in NEPC (2013). Water ILs were selected based on water environmental values of the Ross River Basin and Magnetic Island Environmental Values and Water Quality Objectives (EHP 2013) for groundwater, The Town Common, Ross Creek, Bohle River and Pallarenda waters.

Prescribed environmental values for which the source-pathway-receptor linkages are potentially complete for surface water are listed below (refer Section 5.1.2):

— aquatic ecosystem — human consumer — primary recreation — secondary recreation — visual recreation — cultural and spiritual values; and — public amenity and safety.

Prescribed environmental values for groundwater for which the source-pathway-receptor linkages are potentially complete are listed below and these vary depending on whether the aquifer is freshwater or saline, with the latter having substantially diminished value (refer Section 5.1.2):

— aquatic ecosystem (groundwater discharged to waterways) — irrigation (non-potable domestic irrigation) — farm supply/use (non-potable domestic use) — stock water (poultry most probable use) — human consumer (groundwater discharged to waterways) — primary recreation (groundwater discharged to waterways) — secondary recreation (groundwater discharged to waterways) — visual recreation (groundwater discharged to waterways) — cultural and spiritual values (groundwater discharged to waterways); and — public amenity and safety.

Thus, the ILs for which criteria have been established are presented in Table 6.2 and Table 6.3 and have been adopted from the following guidelines:

— HEPA 2018, PFAS National Environmental Management Plan, January 2018.

— freshwater and marine water, 95% level of protection (% species) due to the moderately disturbed ecosystems of the Town Common, Bohle River and Cleveland Bay (EHP, 2013b).

— freshwater and marine water, 99% level of protection (% species) due to the moderately disturbed ecosystems of the Town Common, Bohle River and Cleveland Bay (EHP, 2013b).

— DoH 2017, Health Based Guidance Values for PFAS for use in Site Investigations in Australia.

— drinking water quality value — recreational water quality value.

WSP acknowledge that the criteria for recreational water is based on incidental ingestion of water by human receptors, such as in the event of swimming and sprinkler-play, on the same frequency as drinking (i.e. daily). With the exception of domestic scenarios, it is unlikely that incidental ingestion of water would occur at this frequency in the waterways within the IA. This assumption is made because submersion in natural waters in this landscape pose unacceptable acute safety risks associated with wildlife, including Saltwater Crocodiles and Irukandji Jellyfish. The recreational value has still been adopted as a conservative approach in the DSI (WSP 2018a) and Seasonal Monitoring Report 1, however exceedance of


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this trigger level outside of a domestic setting does not equate to a potentially unacceptable risk given this conservatism, as assessed in the HHRA (WSP 2018b).

WSP acknowledge that the PFAS NEMP (HEPA 2018) advises that the 99% species level of protection be applied to moderately disturbed systems for chemicals that bioaccumulate and biomagnify in wildlife (such as PFAS). However, planned advancement of biota sampling in the aquatic ecosystems of the IA renders the application of the 99% screening criteria redundant and the 95% criteria is considered adequate at this stage of the investigation.


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Table 6.1 Soil investigation levels

ANALYTE EXPECTED UNDILUTED LEVEL OF

REPORTING

HUMAN HEALTH(1) ECOLOGICAL(2)

Residential with garden/ accessible

soil

Residential with minimal opportunities for soil access

Public open space

Commercial/ Industrial areas

Public open space – direct

exposure

Residential – indirect exposure

Commercial/Industrial – indirect exposure

PFAS

PFOS 0.0002 mg/kg 0.009 mg/kg 2 mg/kg 1 mg/kg 20 mg/kg 1 mg/kg 0.01 mg/kg 0.14 mg/kg

PFHxS 0.0002 mg/kg NE NE NE

PFOA 0.0002 mg/kg 0.1 mg/kg 20 mg/kg 10 mg/kg 50 mg/kg 10 mg/kg NE NE

(1) HEPA 2018 PFAS National Environmental Management Plan. Human Health screening values

(2) HEPA 2018 PFAS National Environmental Management Plan. Interim soil ecological guidelines

NE: Non existent


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Table 6.2 Groundwater investigation levels


REPORTING

POTENTIAL AQUIFER ENVIRONMENTAL VALUE


Drinking water Direct contact/ recreation

Maintenance of ecosystem (95% species protection)

Stock water

Irrigation/ agriculture

Aquaculture

Ingestion Aesthetics Fresh Marine

PFAS

PFOS 0.01 µg/L NR 0.07 µg/L (1) NE 0.7 µg/L (1) 0.13 µg/L (2) 32 µg/L (2) NE NE NE

PFHxS 0.01 µg/L NR NE NE NE NE NE NE

PFOA 0.01 µg/L NR 0.56 µg/L (1) NE 5.6 µg/L (1) 220 µg/L (2) 220 µg/L (2) NE NE NE

(1) DoH 2017 Health Based Guidance Values for PFAS for use in Site Investigations in Australia (2) HEPA 2018 PFAS National Environmental Management Plan.

NE: Non existent NR: Not relevant

Table 6.3 Surface water investigation levels


REPORTING

POTENTIAL AQUIFER ENVIRONMENTAL VALUE


Drinking water Direct contact/ recreation

Maintenance of ecosystem (95% species protection)

Stock water

Irrigation/ agriculture

Aquaculture

Ingestion Aesthetics Fresh Marine

PFAS

PFOS 0.01 µg/L NR 0.07 µg/L (1) NE 0.7 µg/L (1) 0.13 µg/L (2) 32 µg/L (2) NE NE NE

PFHxS 0.01 µg/L NR NE NE NE NE NE NE

PFOA 0.01 µg/L NR 0.56 µg/L (1) NE 5.6 µg/L (1) 220 µg/L (2) 220 µg/L (2) NE NE NE

(1) DoH 2017 Health Based Guidance Values for PFAS for use in Site Investigations in Australia (2) HEPA 2018 PFAS National Environmental Management Plan

NE: Non existent NR: Not relevant


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7 RESULTS

7.1 RAINFALL DURING THE SEASONAL MONITORING The Seasonal Monitoring field work was undertaken between March and September 2018.

Records of rainfall that occurred before and during the fieldwork program were obtained from the BOM Townsville Airport weather station (station identification 032040). Rainfall data is summarised in Table 7.1.

Discharge water sampling was conducted between 1 to 5 March 2018 during and immediately following a peak rainfall event and the ‘post-wet season’ environmental sampling (sediment, surface water and groundwater) was conducted between 9 to 20 April 2018, approximately one month after the conclusion of the rainfall event. A description of surface water conditions during this event is presented in Section 7.4.1.

Surface soil sampling and residential bore sampling was conducted in June 2018.

Additional soil and biota sampling was conducted on 3 August and 28 September 2018.

During the March 2018 discharge sampling event, 166.6 mm of rainfall occurred over the first two days of sampling, and no precipitation was reported for the remaining three days of the sampling event.

The monthly rainfall for March was significantly above the monthly mean for March; however, the majority of this rainfall fell on one day (1 March 2018).

During the April ‘post-wet weather’ sampling investigation, 0.6 mm of rainfall fell over the last two days of the first week of sampling and 0.2 mm fell on Sunday 15 April, with the remainder of the sampling period experiencing no precipitation. The highest daily rainfall total for April was 6.6 mm, which fell 7 days prior to the start of the groundwater, surface water and sediment sampling program.

Table 7.1 Rainfall during fieldwork – Seasonal Monitoring fieldworks were undertaken in March 2018 – September 2018

MONTH MONTHLY RAINFALL TOTAL (mm)

MEAN MONTHLY RAINFALL (mm)

HIGHEST DAILY RAINFALL TOTAL (mm)

May 2017 166.4 33.5 120.8

June 2017 0.4 21.0 0.4

July 2017 0.6 14.7 0.4

August 2017 4.4 15.9 4.0

September 2017 0.8 10.4 0.8

October 2017 76.8 24.1 20.2

November 2017 34.4 58.1 19.8

December 2017 16.8 125.0 6.0

January 2018 115.7 266.7 31.4

February 2018 285.0 305.5 93.6

March 2018 343.2 194.0 147.6

April 2018 10.2 65.0 6.6

May 2018 1.8 33.1 0.8


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MONTH MONTHLY RAINFALL TOTAL (mm)

MEAN MONTHLY RAINFALL (mm)

HIGHEST DAILY RAINFALL TOTAL (mm)

June 2018 2.2 20.7 1.0

July 2018 13.6 14.7 12.4

August 2018 0.0 15.9 0.0

September 2018 16.4 10.3 13.4

7.2 SUB-SURFACE CONDITIONS

7.2.1 Sub-surface Soil

The sub-surface conditions encountered in the IA during the Seasonal Monitoring were restricted to shallow samples collected from within 0.1 m of the surface at the Ingham Road Sports Fields, in Garbutt on the eastern boundary of the Base and to a maximum depth of 0.3 m in a number of selected residences in Garbutt, Rowes Bay and Pallarenda.

Non-residential soil sample locations are shown on Figure 7, Appendix A. Residential soil sample locations are not shown to protect resident’s privacy.

A more detailed description of the individual sample locations and associated lithology are provided below.

Table 7.2 presents a descriptive summary of the lithology encountered in the area of the Ingham Road sports fields (BH063 – BH066).

Table 7.2 Ingham Road sports fields observed soil lithology summary

LITHOLOGY DESCRIPTION

TOPSOIL Sandy soil with minor angular gravel was encountered. The soil was light brown, with some fine angular gravel, organic matter and roots. The soil was dry and hard.

Table 7.3 to Table 7.5 present a descriptive summary of the lithology encountered during the off-Base investigation at Garbutt, Pallarenda and Rowes Bay.

Table 7.3 Garbutt community observed soil lithology summary


FILL Fill was encountered in both locations sampled immediately to the east of the Base in Garbutt (BH061 & BH062). The fill consisted of sand and fine gravel with some roots and fragments of glass. The fill was dry and hard.

TOPSOIL Soil samples were collected from private resident’s lawns and garden at two locations in Garbutt. Samples comprised dry sandy soil and moist organic-rich garden soil.

Table 7.4 Pallarenda observed soil lithology summary


TOPSOIL Topsoil was collected from a garden bed at a private resident’s property in Pallarenda. The soil was sandy with a high percentage of organic material including roots and plant matter. The soil was moist.


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Table 7.5 Rowes Bay observed soil lithology summary


TOPSOIL Topsoil was collected from private resident’s lawns and garden at two locations in Rowes Bay. Soils were sandy with a high percentage of organic material including roots and plant matter. The soil was moist.

7.2.2 ON-BASE SURFACE SEDIMENT

Sediment samples were collected during the Seasonal Monitoring, between 9 and 20 April 2018, at specified drainage locations across the Base. Sample locations are shown on Figure 8, Appendix A and are generally consistent with DSI (WSP 2018a) sampling locations. Photos of sample locations are included in Appendix D.

The surface conditions encountered in the on-Base drains consisted of either concrete, asphalt, grass or natural wetland. Only locations containing deposited material were selected for sediment sampling, five target sample locations were devoid of sediment and are not discussed further. Four samples collected from grass-covered swales were logged as sediment but are considered more akin to soil samples (SD023a, SD23b, SD23c and SD122), and have been considered as such for screening purposes.

Table 7.6 presents a descriptive summary of the sediments encountered during the Seasonal Monitoring sampling.

Table 7.6 Base sediment sample ID and lithology summary

LOCATION SITE ID DRAIN TYPE SEDIMENT DESCRIPTION

Domestic area, eastern boundary of Base

SD001A Concrete drain Gravelly sand; brown, fine to coarse grained sand, fine gravel, sub-angular, wet.

Domestic area SD010S Concrete Sandy silt; brown/black, fine to coarse grained sand, wet.

North-western Base boundary

SD012 Natural watercourse, edge of bank with standing water

Clay, grey, moderate plasticity, wet.

North-western Base boundary

SD013 Natural watercourse, dry bed of pond

Silt; grey, fine grained with organic matter and rootlets, wet.

Western Base boundary

SD015 Unlined table drain Gravelly sand; brown/grey with fine to coarse grained sand and fine gravel, wet.

Western Base boundary

SD016 Concrete drain Silt; grey with traces of fine gravel, wet.

5 AVN SD019 Unlined table drain, downstream of 5 AVN separator

Silty sand; grey with trace low plasticity clay, fine to coarse grained sand, wet.

Ingham Road sports fields

SD020 Grassed swale Silty sand with traces of gravel; pale brown, fine to coarse grained sand, fine gravel, sub-angular, loose, poorly sorted, some organic matter, wet.

Ingham Road sports fields

SD021 Unlined table drain Silty sandy clay; dark brown, low plasticity, fine to coarse grained sand, organic matter, wet.

OLAs SD023a Grassed swale Gravelly sandy clay fill; brown with low plasticity, coarse grained sand and fine to medium gravel, dry.


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LOCATION SITE ID DRAIN TYPE SEDIMENT DESCRIPTION

OLAs SD023b Grassed swale Gravelly sandy clay fill; brown with low plasticity, coarse grained sand and fine to medium gravel, dry.

OLAs SD023c Grassed swale Silty clay fill with trace fine grained sand; dark brown with organic matter and roots, organic odour, moist.

Fuel farm SD024 Grassed swale Silty sand; brown, fine to coarse grained, dry.

38 SQN SD025 Asphalt Silty sand; brown silt with brown fine to coarse grained sand, dry.

Fire training ground NQ0105 and NQ0107

SD039 Grassed swale Silty clay; black, trace fine to coarse grained sand, organic matter.

Fire training ground NQ0105 – northern boundary of site

SD103 Concrete drain Clayey silt with trace fine gravel; brown with low plasticity, organic matter, wet.

Fire training ground NQ0105 – north of main runway

SD104 Concrete drain Clayey silt; fine to medium grained sand with organic material, wet.

Fire training ground NQ0105 – north of main runway

SD105 Concrete drain Sandy silt; brown, fine grained sand, dry.

Domestic area, eastern boundary of Base

SD121 Concrete drain Gravelly sand; brown, fine to coarse gravel, angular to sub-angular, fine to coarse grained sand, dry.

Former fire training ground NQ0054 –

SD122 Grassed swale Fine grained sand with some gravel, dry.

5 AVN SD123 Unlined table drain, above triple interceptor

Clayey silt; grey, low plasticity with traces of fine to coarse gravel, wet.

Wetlands to west of 5 AVN

SD124 Natural wetland, dry bed of pond

Silty sandy clay; brown, low plasticity, fine grained sand, moist.

North of 5 AVN hardstand

SD125 Natural watercourse, bed of pond

Silt; grey with traces of fine gravel, wet.

OLAs SD126 Natural watercourse, bed of pond

Silty clay; dark brown, low plasticity, organic matter rich, organic odour, wet.

OLAs SD131 Natural watercourse, bed of pond

Silty-clay, dark brown, organic matter rich.

OLAs – fire training ground NQ0106

SD301 Concrete drain Silty clay; brown with low plasticity, dry.

OLAs – fire training ground NQ0106

SD302 Concrete drain Silty clay; brown with low plasticity, dry.


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7.2.3 OFF-BASE SURFACE SEDIMENT

Sediment samples were collected from a variety of man-made and natural drainage channels across off-Base areas within the IA. Sample locations are shown on Figure 8, Appendix A and are generally consistent with DSI (WSP 2018a) sampling locations. Some sample locations were inaccessible due to flooding and safety concerns associated with long reeds and the possibility of snake bite.

Table 7.7 to Table 7.13 present a descriptive summary of the sediments encountered during the off-Base investigations at Cleveland Bay, Rowes Bay, Garbutt, Bohle, Town Common and the background locations.

Table 7.7 Cleveland Bay (Three Mile Creek Catchment) sediment sample ID and lithology summary

LOCATION SITE ID

WATERCOURSE DESCRIPTION

SEDIMENT DESCRIPTION

Outside northern Base boundary, upstream of golf course

SD101 Unlined grass swale Silty clayey sand; brown, organic matter, wet.

Outside northern boundary of Base, at Base discharge

SD102 Natural watercourse, bed of pond

Silty clay with decomposing organic matter; wet, organic odour.

East of the northern Base boundary, upstream of Base discharge

SD107 Natural wetland, edge of pond

Gravelly sandy clay with organic matter; brown, wet, mild organic odour.

Mouth of Three Mile Creek SD210 Natural estuary, tidal Silty clay; brown/black, organic odour, wet.

Table 7.8 Rowes Bay & Belgian Gardens (Mundy Creek Catchment) sediment sample ID and lithology summary

LOCATION SITE ID WATERCOURSE DESCRIPTION

SEDIMENT DESCRIPTION

East of Base, channel behind Rowes Bay

SD108 Natural wetland, tidal Silty clay with sand and some gravel; dark brown with organic matter, fine to coarse grained sand, organic odour, wet.

East of Base, mouth of Mundy Creek

SD109 Natural watercourse modified into drain, tidal

Sandy silt; pale brown, wet.

East of Base, Mundy Creek downstream of Belgian Gardens Cemetery


Silty sandy clay; grey with organic matter, strong organic odour, wet.

East of Base, Mundy Creek adjacent to Cleveland Bay Youth Detention Centre



East of Base, Mundy Creek at entrance to Belgian Gardens Cemetery




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Table 7.9 Garbutt (Mundy Creek Catchment) sediment sample ID and lithology summary

LOCATION SITE ID

DRAIN TYPE SEDIMENT DESCRIPTION

East of Base boundary, drain from northern section of Townsville Airport

SD113 Unlined table drain Silty sandy clay; grey with organic matter, strong organic odour, wet.

East of Base, at Old Common Road crossing of drain


East of Base, at John Milton Black Drive crossing of drain

SD117 Unlined table drain Silty sandy clay; dark grey/brown with low plasticity, wet.

East of Base, lower end of drain that drains southern Townsville Airport area and domestic area of Base


Drain on eastern boundary of domestic area of Base

SD121 Unlined table drain Gravelly sand; brown, fine to coarse grained sand, fine to coarse gravel, angular to sub-angular, dry.

Table 7.10 Garbutt (Louisa and Peewee Creek Catchment) sediment sample ID and lithology summary

LOCATION SITE ID


Louisa Creek at Ingham Road crossing

SD014 Natural watercourse Clay, dark brown, organic rich.

South of Base, headwaters of Peewee Creek

SD120 Unlined table drain Silty sandy clay; dark brown with organic matter, saturated with slight organic odour.

Louisa Creek at Woolcock Street crossing

SD127 Natural watercourse, edge of bank adjacent to standing water

Silty sandy clay; brown, fine grained sand, wet.

Louisa Creek at Bayswater Road crossing

SD128 Natural watercourse modified into drain

Silty gravelly sand; brown, fine to coarse grained sand, fine to medium gravel, sub-angular, wet.


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Table 7.11 Bohle River sediment sample ID and lithology summary

LOCATION SITE ID


Bohle River at Bruce Highway crossing

SD129 Natural watercourse Sand; brown, fine to coarse grained sand, wet.

Bohle River upstream of Bruce Highway crossing

SD201 Natural watercourse Sand; brown, fine to coarse grained sand, wet.

Bohle River upper estuary SD202 Natural estuary, tidal Sandy silty clay; brown/black, fine grained sand, wet.

Bohle River lower estuary SD203 Natural estuary, tidal Sand; brown, fine to coarse grained sand, wet.

Mouth of Bohle River SD204 Natural estuary, tidal Sandy silty clay; brown/black, fine grained sand, wet.

Table 7.12 Town Common (Louisa Creek Catchment) sediment sample ID and lithology summary

LOCATION SITE ID


North-west of Base, southern section of Town Common

SD110 Natural wetland Silty clay; brown/black, organic matter rich with roots, organic odour, wet.

North-west of Base, southern section of Town Common

SD111 Natural wetland Sandy gravel with silt; brown, fine to coarse grained sand, fine gravel.

West of Base, outfall of Mount St John waste water treatment plant

SD112 Unlined table drain Silty clay; brown/grey with organic matter, wet.

North-west of Base, Louisa Creek upper estuary

SD205 Natural estuary, tidal Clayey silty sand; brown/black, fine grained sand, sticky, organic matter, wet.

North-west of Base, Louisa Creek lower estuary

SD206 Natural estuary, tidal Gravelly sand; brown, fine to coarse grained sand, fine to coarse gravel, some coral, wet.

North-west of Base, northern section of Town Common

SD207 Natural estuary, tidal Clayey silty sand; brown/black, fine grained sand, sticky, organic matter, wet.


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Table 7.13 Background locations (Stuart and Althaus Creek Catchment and Ross Creek Catchment) sediment sample ID and lithology summary

LOCATION SITE ID


South east of Base, Ross Creek catchment (approximately 1.6 km), up-gradient

SD130 Sedimentation basin Sandy silty clay; dark brown, low plasticity, organic matter rich, organic odour, wet.

Alligator Creek freshwater, approximately 24 km south-east of Base

SD211 Natural watercourse Silty sand, light brown, low plasticity, organic matter rich.

Stuart Creek estuary, approximately 10 km south-east of Base

SD212 Natural estuary Silty clay; brown with organic matter, saturated with organic odour.

Mouth of Althaus Creek, approximately 20 km north-west of Base

SD213 Natural estuary Silty clay; brown/black with organic matter, saturated with organic odour.

7.2.1 PARTICLE SIZE DISTRIBUTION

All sediment samples were submitted for PSD, with the exception of locations with insufficient sediment sample. A summary of on-and-off-Base PSD results is presented in Table 7.14 and Table 7.15.

Table 7.14 Summary of on-Base particle size distribution results

LOCATION SAMPLE ID SAMPLE DEPTH (mbgl)

CLAY IN SOIL %

SILT (2–75 µm)

%

SAND (0.075–

2 mm) %

GRAVEL (2-60 mm)

%

Domestic area SD010S <0.1 <1 49 46 5

NW Base boundary SD012 <0.1 <1 91 9 <1

NW Base boundary SD013 <0.1 <1 69 24 7

W Base boundary SD015 <0.1 9 1 35 55

5AVN SD019 <0.1 14 21 59 6

Ingham Rd Sports Fields

SD020 <0.1 11 – – –

Ingham Rd Sports Fields

SD021 <0.1 12 – – –

NQ0055 & NQ0107 SD039 <0.1 41 42 16 1

NQ0105 SD101 <0.1 8 – – –

NQ0105 SD102 <0.1 25 – – –

Mount St John SD112 <0.1 18 15 57 10

Domestic area SD121 <0.1 2 4 71 23

5AVN SD123 <0.1 22 19 51 8


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CLAY IN SOIL %

SILT (2–75 µm)

%

SAND (0.075–

2 mm) %

GRAVEL (2-60 mm)

%

5AVN SD124 <0.1 28 35 35 2

W of Runway 13/31 & Emergency Response Areas

SD125 <0.1 <1 41 45 14

The Common discharge SD131 <0.1 53 41 3 3

NQ0106 & OLAs SD301 <0.1 4 36 8 52

Table 7.15 Summary of off-Base particle size distribution results


CLAY IN SOIL %

SILT (2–75 µm)

%

SAND (0.075–2 mm) %

GRAVEL (2-60 mm)

%

Louisa Creek SD014 <0.1 16 7 74 3

Louisa Creek SD127 <0.1 20 26 42 12

Louisa Creek SD128 <0.1 18 21 55 6

Louisa Creek SD205 <0.1 29 17 45 9

Louisa Creek SD206 <0.1 22 11 50 17

Rowes Bay Wetland SD107 <0.1 18 16 62 4

Rowes Bay Wetland SD108 <0.1 31 28 38 3

Mundy Creek SD109 <0.1 33 55 12 <1

Mundy Creek SD114 <0.1 19 35 44 2

Mundy Creek SD115 <0.1 33 56 10 1

Mundy Creek SD116 <0.1 24 14 60 2

Mundy Creek SD117 <0.1 27 33 28 12

Mundy Creek SD118 <0.1 29 50 21 <1

Mundy Creek SD121 <0.1 2 4 71 23

Mundy Creek SD208 <0.1 33 55 12 <1

Town Common SD110 <0.1 14 – – –

Town Common SD111 <0.1 9 – – –

Town Common SD207 <0.1 29 32 35 4

Peewee Creek SD120 <0.1 12 13 63 12

Bohle River SD129 <0.1 3 3 93 1

Bohle River SD201 <0.1 <1 <1 68 32

Bohle River SD202 <0.1 37 48 15 <1


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CLAY IN SOIL %

SILT (2–75 µm)

%

SAND (0.075–2 mm) %

GRAVEL (2-60 mm)

%

Bohle River SD203 <0.1 6 <1 93 1

Bohle River SD204 <0.1 28 24 39 9

Three Mile Creek SD210 <0.1 20 31 49 <1

Alligator Creek SD211 <0.1 4 4 58 34

Stuart Creek SD212 <0.1 25 24 37 14

Althaus Creek SD213 <0.1 33 58 7 2

7.3 HYDROGEOLOGY

7.3.1 RESIDENTIAL BORE USE SURVEY AND TARGET BORES

As part of the DSI (WSP 2018a), a Water Use Survey was distributed to all properties within the IA between 5 June to 9 June 2017. As at 30 September 2018, 168 Water Use Surveys have been received via mail, email, phone and in person. Twenty-eight respondents to the survey indicated that they had bores on their property, 22 of which were operable and 18 of which were actively in use for water supply. These bores were sampled between August 2017 and September 2018 and results are contained in the DSI (WSP 2018a).

Post-wet season sampling was conducted at all of the previously sampled residential bores where the landholder was able to be contacted to schedule the sampling event. Twenty two landholders granted access to their properties and samples were collected as per Section 5.2.5. One sample was also collected from a swimming pool that had been filled using groundwater (reportedly by a previous resident). Analytical results are summarised in Section 7.6.4.

With the exception of three residents, all residents who responded regarding the use of extracted groundwater on their properties stated that the water was not used for drinking or domestic use.

Two residents in Pallarenda, indicated they used their bore water intermittently on their vegetable gardens, and one resident in Garbutt, indicated they used their bore water occasionally to water their fruit trees. Use of groundwater at all three sites was anecdotally limited to watering lawns and gardens. The extraction bores were either in disuse or connected directly to garden/lawn irrigation systems and/or hoses.

One resident in Pallarenda had a swimming pool that had been topped-up with groundwater by the previous resident and this water was sampled. No extracted groundwater was identified to be stored in tanks.


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7.3.2 GROUNDWATER ELEVATION AND FLOW DIRECTION

Groundwater gauging was undertaken at each monitoring well during the post-wet season groundwater monitoring event (GME) undertaken on 9–20 April 2018. Groundwater gauging was undertaken prior to sample collection. The locations of groundwater wells sampled as part of the Seasonal Monitoring are shown on Figure 11, Appendix A. Groundwater gauging data from the Seasonal Monitoring is presented in Table 1, Appendix B and summarised in Table 7.16.

Table 7.16 Groundwater gauging data

GAUGING EVENT NO. WELLS

MIN SWL (mbtoc)

MAX SWL (mbtoc)

MIN RWL (m AHD)

MAX RWL (m AHD)

GME: 09–20 April 2018 134 0.240 (MW121_S) 6.195 (MW261_S) 0.568 (MW231_S) 10.387 (MW261_S)

Note: mbtoc = metres below top of casing SWL = standing water level RWL = relative water level mAHD = metres Australian Height Datum

Groundwater elevation maps which have been extrapolated based on groundwater gauging data from the post-wet season sampling event are presented in Figures 11, Appendix A. Groundwater levels were generally higher than observed during the DSI (Section 8.2.3).

Based on the groundwater elevation data, groundwater is inferred to generally flow in a northerly direction across the IA towards the Town Common and Rowes Bay. An elongated piezometric high extends from Garbutt south of the Base in a north-north-easterly direction through the domestic area of the Base to Townsville Airport. Therefore, groundwater flow from the Base is partially radial, being westward from 5 AVN, north-westerly from the fire station and OLAs, north-easterly from Townsville Airport and easterly from the domestic area of the Base. Groundwater flows westerly to Peewee Creek/Louisa Creek, north-westerly to the Town Common wetlands and north-easterly and easterly to the Mundy Creek catchment and Rowes Bay. Areas of elevated water levels appear to exist in the palaeodune system at Rowes Bay. This is generally consistent with the groundwater flow directions observed in the DSI (WSP 2018a).

The regional groundwater gradient has been calculated to be approximately 0.0007 m/m to the north; however, local hydraulic gradients from 5 AVN to the north-west and from the domestic area of the Base to the east north-east are calculated to be approximately 0.002 m/m. These gradients are similar to those observed during the DSI (WSP 2018a).

7.3.3 GROUNDWATER GEOCHEMICAL PARAMETERS

Groundwater geochemical parameters were measured during the GME. Readings were collected in situ except where the water table was too deep for the WQ meter cable to reach the groundwater table. Readings were collected post-sampling and are considered representative of in situ groundwater quality. Measurements and field observations are presented in Table 2, Appendix B.

Geochemical parameters measured during the GME are summarised below.

— Dissolved oxygen ranged from 0.04 mg/L (MW112) to 3.44 mg/L (MW269), indicating anaerobic to oxidising conditions.

— EC measurements ranged from 16.32 µS/cm (MW213) to 120,406 µS/cm (MW203), indicating fresh to hypersaline conditions. No apparent trends are discernible in salinity across the IA, except that the wells located on Rowes Bay are generally fresh.

— pH measurements ranged between 3.67 (MW207) and 8.34 (MW090) pH units; however, the majority of readings were between 6.0 and 7.5 pH units, indicating slightly acidic to neutral conditions. The acidic wells are generally located in the Town Common or the Louisa Creek wetlands and north of Townsville Airport, and are potentially associated with potential acid sulfate soils.


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— Redox measurements were between -198.2 (MW208) and 177 (MW207) millivolts (mV), indicating reducing to moderately oxidising conditions. No discernible trends are apparent in the distribution of redox measurements across the IA, except the wells along the shore front at Rowes Bay, where groundwater exhibits reducing conditions.

— Groundwater temperatures ranged from 21.5 degrees Celsius (°C) (MW009) and 29.9°C (MW260), with the majority of samples ranging between 25°C and 31°C.

7.3.4 HYDRAULIC CONDUCTIVITY

Hydraulic conductivities (K) for groundwater were derived from previous investigations at the Base (ERM 2005, SKM 2008). No additional hydraulic conductivity investigations were undertaken during the post-wet season GME. The results of the various investigations are presented in Section 7.3.4 of the DSI (WSP 2018a).

In summary, the hydraulic conductivity of the sandy/silty clays beneath the Base range from 1.89 x 10-7 to 4.5 x 10-6

m/sec, with an average of 1.55 x 10-7 m/sec (0.013 m/day). The silty clays in the western area of the Base (MW100, MW101, MW105, MW106, MW108, MW112 and MW113) have a slightly lower K (average of 7.70 x 10-7 m/sec) than the sandy silty clays beneath the former fire training ground NQ0054 (MW116, MW118 and MW119), which have an average K of 3.71 x 10-6 m/sec. The sands beneath the former Rowes Bay landfill have a hydraulic conductivity of approximately 1.35 x 10-5 m/sec (1.2 m/day).

7.4 SURFACE WATER CONDITIONS

7.4.1 OBSERVED CONDITIONS – GENERAL

Immediately after the heavy rainfall event on 1 March 2018, discharge sampling was undertaken at the Base. Flooding on the Base prohibited sampling in two locations (SW131 and SW102) on the first of the five day sampling program. Flooding receded sufficiently to allow surface water sampling at all four target locations by 2 March 2018; however, pooled water remained in several areas across the Base. Flowing water was observed at several creeks off-Base and pooled water was observed in most low-lying areas in parks, grassed areas and in the Town Common during the heavy rainfall event.

During the post-wet season GME (9–20 April 2018) there was little to no rainfall, however, some grassed areas on the Base were saturated from the flooding experienced in March 2018. Aside from tidal flows and the Bohle River, no flowing water was observed in streams in the IA during the GME. Pooled water was observed in several locations off-Base.

Target sample locations are shown on Figure 9, Appendix A. Photographs of discharge sampling locations are included in Appendix D.

7.4.1.1 ON-BASE

Surface water conditions observed during the March 2018 discharge sampling differed to those encountered during the DSI (WSP 2018a) and the post-wet weather GME conducted in April 2018.

In March 2018, pooled water was observed at all discharge locations and on grassed, hardstand, concreted and asphalted areas across the Base. Pooled water covered the road to the southwest of runway 07/25. Active discharge off-Base was observed through drainage runoff into Mundy Creek and via pumping from ponded areas into lake Lydeamore and Three Mile Creek.

Surface conditions remained predominantly dry for the period of the GME and no pooled surface water was observed on any grassed, hardstand, concreted or asphalted areas. Several wetland areas on-Base remained inundated with water from the March 2018 rainfall event and the standing water in these areas remained for several weeks after the rainfall event.


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Several concrete-lined drainage channels had minimal standing water remaining after the wet season (<0.10 m deep). Organic matter was present in some sample locations and turbidity (visually assessed) ranged between low to moderate during the GME.

7.4.1.2 OFF-BASE

THE TOWN COMMON

Widespread flooding in the Town Common was observed from Castle Hill during the March 2018 discharge sampling event. The road leading to the Town Common Conservation Park was closed from the gated entrance due to flooding and pooled water was observed near the roads leading to the Town Common.

The Town Common was inaccessible during the first week of the post-wet season GME in April 2018, due to localised flooding and ‘boggy’ conditions. Where access was restricted, samples were collected from the edges of the main waterbody in the southern section of the Base (SW110 and SW111). Waters had receded sufficiently by the second week of the GME to access the north section of the Town Common. The water was brown and had an observable organic sheen on the surface in places and floating organic matter.

BOHLE RIVER

Surface water sampling along the Bohle River was undertaken during the post-wet season sampling event and conducted from a boat. The height of the water level altered with the tide but generally the River had a maximum of approximately between 1 to 2.5 m of its banks exposed. The river water was observed to be clear to brown with low to high turbidity in the upstream reaches, but became less turbid and light brown in colour as the tidal influence increased.

MUNDY CREEK

The upper reaches of the Mundy Creek catchment have been heavily modified into unlined drains, except the wetlands between Rowes Bay residential area and Belgian Gardens Cemetery, which has not been dredged. The drains were heavily infested with reeds and weeds during the post wet-season sampling event until the tidal and saltwater influential point is reached, at which point mangroves line the banks of the drains and the watercourses are clear. No running water was observed in the catchment above the tidal zone; however, sufficient standing water was present to allow sampling in all target sampling locations.

LOUISA AND PEEWEE CREEKS

The upper reaches of Louisa and Peewee Creeks had no running water during the post wet-season sampling event and were heavily reed and weed infested. The waters were generally clear. The discharge from the Mount St John WTP enters Louisa Creek approximately 800 m downstream of the Base, and water was observed to be flowing intermittently downstream of this point. Tidal influence was observed approximately 2 km downstream of the discharge point, and mangroves line the creek banks downstream from this location. Fish and invertebrates were commonly observed downstream of the tidal zone.

THREE MILE CREEK

The upper reaches of Three Mile Creek receive water from the Base via the valved pipework on the northern boundary. The water in the tidal section of Three Mile Creek was flowing and at the top of the bank during the discharge sampling in March 2018.

During the post wet-season sampling event the wetlands that feed Three Mile Creek on the northern boundary of the Base contained stagnant ponds of brown water that were heavily weed infested. There was no observed flow from the Base or the wetlands downstream into Three Mile Creek at the time of the sampling event and the tidal section of the creek was separated from surface waters by predominantly dry saline claypans that contained small areas of pooled water.

Rowes Bay Golf Course uses treated water from the Mount St John WTP for irrigation. Runoff from the golf course discharges to Three Mile Creek.


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7.4.2 SURFACE WATER HYDROCHEMICAL PARAMETERS

7.4.2.1 ON-BASE SURFACE WATER HYDROCHEMICAL PARAMETERS

Hydrochemical parameters for surface water samples collected during the March 2018 discharge sample event are summarised below and in Table 7.17 and are included in Table 3, Appendix B. Surface water sampling locations are presented on Figure 9, Appendix A.

— pH ranged between 7.1 and 9.1 indicating neutral to alkaline conditions. — Dissolved oxygen ranged between 1.91 mg/L and 17.86 mg/L indicating aerobic conditions. — Conductivity ranged between 91.3 µS/cm and 1940 µS/cm indicating surface water at the Base is fresh. — Oxidation reduction potential ranged between 76.7 mV and 173.8 mV indicating surface water on the Base exhibits

oxidising conditions.

Surface waters were generally clear during the discharge sampling, with turbidity and EC increasing as flow rates lessened (Table ).

Table 7.17 Surface water discharge hydrochemical parameters (discharge sampling event)

SURFACE WATER ID

DATE SAMPLED

PH TEMPERATURE (°C)

EC (µS/cm) REDOX (MV) DO (mg/L)

SW132 1/03/2018 7.75 27.9 843 173.8 8.48

2/03/2018 8.29 29.7 984 127.2 12.72

3/03/2018 8.90 33.4 1532 76.7 16.64

4/03/2018 9.10 31.7 1836 101.2 17.86

5/03/2018 9.03 32.8 1940 89.1 17.19

SW123 1/03/2018 7.76 27.0 127.6 141.0 4.43

2/03/2018 7.76 29.6 133.9 128.9 6.82

3/03/2018 8.52 31.4 219.8 94.8 8.80

4/03/2018 8.29 30.6 551 111.3 9.06

5/03/2018 7.63 32.0 932 117.6 7.80

SW131 1/03/2018 Unable to access due to flooding

2/03/2018 7.10 30.2 490.8 105.9 1.91

3/03/2018 7.31 32.2 573 91.3 2.07

4/03/2018 7.40 33.4 539 128.6 4.79

5/03/2018 7.70 35.6 953 114.6 10.67

SW102 1/03/2018 Unable to access due to flooding

2/03/2018 7.27 30.8 91.3 129.2 5.18

3/03/2018 7.30 30.5 161.2 110.5 4.44

4/03/2018 7.21 29.2 232.8 124.0 2.13

5/03/2018 7.21 33.0 322.7 122.8 3.29


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Hydrochemical parameters for surface water samples collected on-Base during the post wet-season sampling event are summarised below and in Table 7.18 and are included in Table 3, Appendix B. Surface water sampling locations are presented on Figure 9, Appendix A.

— pH ranged between 6.33 and 9.08 indicating neutral to alkaline conditions. — Dissolved oxygen ranged between 2.44 mg/L and 9.96 mg/L indicating aerobic conditions. — Conductivity ranged between 679 µS/cm and 9,990 µS/cm indicating surface water at the Base is fresh. — Oxidation reduction potential ranged between -14.3 mV and 35 mV indicating surface water on the Base exhibits

reducing and oxidising conditions.

Hydrochemical parameters during the post wet-season GME were generally similar to those recorded during the DSI (WSP 2018a).

Table 7.18 On-Base surface water hydrochemical parameters (post wet-season sampling event)

SURFACE WATER ID


EC (µS/cm) REDOX (ORP) DO (mg/L)

SW001A 9.08 27.9 3,147 42.3 9.96

SW010S 8.19 32.4 1,915 19.0 4.05

SW016 6.33 24.6 679 -14.3 2.48

SW019 8.91 25.2 3,135 53.0 9.69

SW039 7.76 35.0 9,990 33.8 4.97

SW103 7.03 25.7 1,620 38.2 2.44

SW121 Dry

SW122 Dry

SW123 7.96 30.2 1,103 5.0 6.46

SW125 7.54 30.3 2,526 4.6 3.55

7.4.2.2 OFF-BASE SURFACE WATER HYDROCHEMICAL PARAMETERS

Hydrochemical parameters for surface water samples collected off-Base are summarised below, presented in Table 7.19 and are included in Table 3, Appendix B. Figure 9, Appendix A displays surface water sampling locations.

— pH ranged between 6.36 and 8.54 indicating neutral to alkaline conditions. — Dissolved oxygen ranged between 0.002 mg/L and 7.23 mg/L indicating aerobic conditions. — Conductivity ranged between 228.5 µS/cm and 36,951 µS/cm indicating surface water off-Base ranged from fresh

to marine salinity. — Oxidation reduction potential ranged between -75.6 mV and 446.5 mV indicating surface water off-Base exhibits

reducing and oxidising conditions.


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Table 7.19 Off-Base surface water hydrochemical parameters

SURFACE WATER ID



SW014 6.36 26.7 2,092 16.8 2.49

SW017 7.07 27.5 3,287 86.2 1.79

SW020 7.67 29.8 228.5 56.1 6.20

SW021 Dry

SW107 6.47 23.6 14,688 -75.6 0.14

SW108 8.54 32.7 19,049 43.6 7.23

SW109 7.82 29.6 36,951 59.6 4.18

SW110 6.36 25.9 958 42.9 –

SW111 6.37 26.7 696 33.1 –

SW112 6.38 28.6 1,420 21.9 5.65

SW113 6.86 27.6 1,390 61.0 –

SW114 6.89 29.4 1,915 88.1 4.05

SW115 7.00 29.1 990.0 -2.4 2.20

SW116 7.11 28.5 10,678 77.5 –

SW117 7.62 29.5 3,958.0 446.5 1.70

SW118 6.83 28.3 1,291 51.1 0.02

SW120 7.42 28.0 3,601 -22.1 1.04

SW126 7.94 30.0 738 16.3 0.55

SW127 8.20 22.6 3,729 59.2 –

SW128 7.61 28.7 1,857 72.8 –

SW129 7.86 28.2 936 15.7 5.48

7.4.3 AQUATIC BIOTA / SURFACE WATER CO-LOCATIONS

Aquatic biota samples were not collected during the Seasonal Monitoring.

Surface water samples were collected from twelve locations that were co-located with biota sampling completed by WSP in July 2017, including two freshwater and ten estuarine locations (Figure 9, Appendix A). One location (SW209) could not be accessed due to flooding and is not discussed further. Water at the freshwater sites was flowing and turbidity was low. Hydrochemical parameters for surface water samples collected from the biota co-locations during the post wet-weather event are summarised below and presented in Table 7.20 (freshwater) and

Table 7.21 (estuarine).

— At the two freshwater sites (SW201 and SW211) pH ranged between 6.37 and 7.00 indicating slightly acidic to neutral conditions. At the eight estuarine sites (SW202-SW206, SW208, SW210, and SW212) pH ranged between 6.22 and 7.65 indicating slightly acidic to neutral conditions.


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— Dissolved oxygen at the freshwater sites ranged between 4.82 mg/L and 5.13 mg/L indicating aerobic conditions. Dissolved oxygen at the estuarine sites ranged between 0.1 mg/L and 5.25 mg/L indicating anaerobic to aerobic conditions.

— At the two freshwater sites conductivity ranged between 600 µS/cm and 735 µS/cm indicating surface water was fresh. At the eight estuarine sites conductivity ranged between and 15,143 µS/cm and 51,542 µS/cm, indicating that surface water was of marine salinity.

— Oxidation reduction potential ranged between -2.3 mV and 8.5 mV at the two freshwater sites, and between 34.1 mV and 105.8 mV at the estuarine sites indicating surface water exhibits reducing and oxidising conditions.

Table 7.20 Fresh surface water hydrochemical parameters

SURFACE WATER ID



SW201 7.0 27.2 735 8.5 4.82

SW211 6.37 25.3 600 -2.3 5.13

Table 7.21 Estuarine surface water hydrochemical parameters

SURFACE WATER ID



SW202 6.35 28.5 32,002 40.4 5.25

SW203 6.22 28.6 48,692 39.9 5.14

SW204 6.34 28.2 51,542 78.6 5.12

SW205 6.33 27.4 15,143 63.2 3.78

SW206 6.38 28.5 38,640 70.7 5.22

SW208 7.52 31.8 23,890 105.8 –

SW210 7.65 28.3 39,366 34.1 0.10

SW212 6.36 27.6 22,736 50.3 4.51

7.5 SOIL ANALYTICAL RESULTS Soil analytical results are presented on Figures 12 and 13, Appendix A, and in Table 5, Appendix B, with laboratory certificates contained in Appendix E.

Shallow soil samples were collected from selected residences in Garbutt, Rowes Bay and Pallarenda. Four samples collected from grass-covered swales were logged as sediment but are considered more akin to soil samples (SD023a, SD23b, SD23c and SD122), and have also been considered as such for screening purposes.

Summaries of the results for soil samples against the ILs (Tier 1 screening criteria) detailed in Section 6.2 are tabulated in the sections below for each of the on-Base source areas (Section 7.5.1), off-Base areas of interest (Section 7.5.2) and selected residences (Section 7.5.3). Exceedances of the nominated guidelines are shown on the table in bold text.

In summary:

— PFOS was the most commonly detected PFAS and generally had the highest concentrations in soil — PFHxS was detected in approximately half of the samples in which PFOS was detected, always at lower

concentrations


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— PFOA was only detected at one location (SS204) at a lower concentration than PFOS — other species of PFAS were generally only detected where concentrations of PFOS and PFHxS were elevated; no

other species of PFAS were detected where PFOS was absent — PFHxA, PFHpA, PFDA, PFDoDA and PFUnDA were only detected at one location (SS204) at concentrations

lower than PFOS — PFPeA was detected at one location (SS203) at a concentration lower than PFOS — one exceedance of the commercial/industrial HBGVs for PFOS + PFHxS was detected in soils on-Base (total of

eight samples); and — eight exceedances of the residential HBGV for PFOS and PFHxS were detected in residential soil in Garbutt, Rowes

Bay and Pallarenda (total of 30 samples).

7.5.1 ON-BASE SOURCE AREAS

A summary of the soil results for the Ingham Sports Fields (BH063 – BH066) is presented in Table 7.22.

Table 7.22 Summary of PFAS soil results at Ingham Sports Fields

ANALYTE HEPA 2018 ENVIRONMENTAL

VALUE (mg/kg)

HEPA HEALTH 2018 (mg/kg)

ANALYTICAL RESULTS (mg/kg)

Public Open Space Public Open Space

Maximum Concentration (unsaturated

zone)

Maximum Concentration

(saturated zone)

Samples with Exceedances

PFOS 1 – 0.0134 (BH066) NA NA

PFHxS – 0.0005 (BH064) NA NA

Sum of PFOS & PFHxS

– 1 0.0136 (BH066) NA NA

PFOA 10 10 <LOR <LOR NA

A summary of the soil results from the vicinity of the OLAs (SD023A, SD023B, SD023C) is presented in Table 7.23.

Table 7.23 Summary of PFAS soil results in the vicinity of the OLAs


VALUE (mg/kg)



Industrial / Commercial



zone)


(saturated zone)


PFOS 0.140 – 0.0234 (SD023C)

NA NA

PFHxS – – 0.0131 (SD023C)

NA NA

Sum of PFOS & PFHxS

– 20 0.0365 (SD023C)

NA NA

PFOA – 50 0.0008 (SD023A)

NA NA


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A summary of the soil results from the former fire training ground (NQ0054) (SD122) is presented in Table 7.24.

Table 7.24 Summary of PFAS soil results at the former fire training ground NQ0054


VALUE (mg/kg)






zone)


(saturated zone)


PFOS 0.140 – 0.301 (SD122) NA SD122

PFHxS – – 0.0277 (SD122) NA NA

Sum of PFOS & PFHxS

– 20 0.3290 (SD122) NA NA

PFOA – 50 0.0084 (SD122) NA NA

7.5.2 OFF-BASE SOIL RESULTS

A summary of the soil results collected from the eastern Base boundary in Garbutt (BH061 – BH062) is presented in Table 7.25.

Table 7.25 Summary of PFAS soil results at the eastern Base boundary at Garbutt


VALUE (mg/kg)



Residential Residential Maximum Concentration (unsaturated

zone)


(saturated zone)

Samples with

Exceedances

PFOS 0.01 – 0.0014 (BH061) NA NA

PFHxS – – <LOR NA NA

Sum of PFOS & PFHxS

– 0.009 0.0014 (BH061) NA NA

PFOA – 0.1 <LOR NA NA

7.5.3 RESIDENTIAL SOIL RESULTS

Soil samples were collected from five properties in the suburbs of Garbutt, Rowes Bay and Pallarenda. A summary of the soil results (SS200 – SS206) is presented in Table 7.26.


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Table 7.26 Summary of PFAS soil results in residential property soils


VALUE (mg/kg)



Residential Residential Maximum Concentration (unsaturated

zone)


(saturated zone)


PFOS 0.01 – 0.501 (SS202_1_0.3)

NA SS202_1_0.1, SS202_1_0.3, SS204, SS206, SS206_1_0.1, SS206_1_0.3

PFHxS – – 0.0617 (SS202_1_0.3)

NA NA

Sum of PFOS & PFHxS

– 0.009 0.573 (SS202_1_0.3)

NA SS202_1_0.1, SS202_1_0.3,

SS204, SS204_03, SS204_04,

SS206, SS206_1_0.1, SS206_1_0.3

PFOA – 0.1 0.0086 (SS202_1_0.3)

NA NA

7.6 GROUNDWATER ANALYTICAL RESULTS Groundwater samples were collected from 136 locations, comprising 68 on-Base and 68 off-Base monitoring wells. The groundwater samples were analysed for either the standard suite or ultra-trace 28 PFAS analytical suite (as detailed in Section 1.5.3), major anions and cations. In addition, a selection of samples were analysed for turbidity, total suspended solids, major/minor cations and anions, nutrients (nitrogen, nitrate, nitrite, phosphorus), ferrous iron, BOD, COD and a filtered PFAS 28-suite. The groundwater analytical results are presented in Table 6, Appendix B and shown on Figure 14 to 16 in Appendix A.

Summaries of the results for groundwater sampling against the Tier 1 Screening criteria detailed in Section 6.3 are tabulated in the sections below for each of the on-Base (Section 7.6.1) and off-Base (Section 7.6.2) areas of interest and Residential Bores (Section 7.6.3). It should be noted that the guidelines are applicable at the point of receptor (e.g. surface water discharge, groundwater extraction), not at the point of measurement; therefore, as groundwater is not extracted on-Base, the drinking water and recreational water guidelines are included in the on-Base results for comparative purposes only. Exceedances of the nominated guidelines (ANZECC PFAS freshwater 95%) are shown on the table in bold text.

In summary:

— PFOS was the most commonly detected PFAS and generally had the highest concentrations in groundwater — PFHxS was generally detected where PFOS was detected, usually at lower concentrations — PFOA was usually detected where PFOS was detected, but predominantly at lower concentrations


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— other species of PFAS were generally only detected where concentrations of PFOS and PFHxS were elevated, with the exception of filtered samples, in which lighter species (PFPeS, PFBS, PFPeA, PFBA, PFHxA, PFHpA, PFOA) were detected but PFOS and PFHXs were absent

— PFBS, PFPeS, PFHpS, PFBA, PFPeA, PFHxA and PFHpA were generally detected in wells with high impact, the other PFAS compounds were only detected in isolated wells, though not always those with the highest PFOS and PFHxS concentrations

— the compounds PFTeDA, MeFOSA, EtFOSA, MeFOSE, EtFOSE, EtFOSAA and 10:2 FTS were not detected in on-Base groundwater during the investigation

— the compounds PFDS, PFDoDA, PFTeDA, PFUnDA, PFTrDA, 4:2/6:2/8:2/10:2 FTS, MeFOSA, MeFOSAA, MeFOSE, EtFOSA, EtFOSAA, EtFOSE were not detected in off-Base groundwater during the investigation

— seventy-eight exceedances of drinking water HBGVs and 59 exceedances of ecological ILs were detected on the Base (total of 92 samples); and

— forty-one exceedances of drinking water HBGVs and 21 exceedances of ecological ILs were detected off-Base in the Town Common, Rowes Bay, Belgian Gardens, Garbutt and Bohle (total of 93 samples).

7.6.1 ON-BASE SOURCE AREAS

A summary of the groundwater results for the former fire training area NQ0105 (MW241 and MW242) is presented in Table 7.27.

Table 7.27 Summary of PFAS groundwater results at fire training ground NQ0105

ANALYTE ENVIRONMENTAL VALUE (µg/L) ANALYTICAL RESULTS (µg/L)

Freshwater 95% Species Protection

Drinking Water

Recreational Water Maximum Concentration


PFOS 0.13 – – 0.22 (MW242) MW242

PFHxS – – – 2.23 (MW241) NA

Sum of PFOS & PFHxS

– 0.07 0.7 2.30 (MW241) MW241, MW242

PFOA 220 0.56 5.6 0.0046 (MW243) NA

A summary of the groundwater results for the former fire training ground NQ0106 and the surrounding monitoring wells in the vicinity of the OLAs (MW004, MW122, MW136, MW243 and MW265) is presented in Table 7.28.

Table 7.28 Summary of PFAS groundwater results at fire training ground NQ0106 and the OLAs



Drinking Water

Recreational Water



PFOS 0.13 – – 366 (MW243) MW136, MW243, MW265

PFHxS – – – 1010 (MW243) NA

Sum of PFOS & PFHxS

– 0.07 0.7 1380 (MW243) MW004, MW122, MW136, MW243, MW265

PFOA 220 0.56 5.6 49.2 (MW243) MW243


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A summary of the groundwater results for Pad Brahman and the north-western Base boundary (MW002, MW121, MW135 and MW244) is presented in Table 7.29.

Table 7.29 Summary of PFAS groundwater results at Pad Brahman and the north-western Base boundary



Drinking Water

Recreational Water



PFOS 0.13 – – 16.2 (MW244) MW002, MW121, MW135, MW244

PFHxS - - – 25.9 (MW244) NA

Sum of PFOS & PFHxS

– 0.07 0.7 42.1 (MW244) MW002, MW121, MW135, MW244

PFOA 220 0.56 5.6 0.84 (MW244) MW244

A summary of the groundwater results for the former Runway 13/31 and the western Base boundary (MW056, MW057, MW102, MW104, MW112, MW245 and MW246) is presented in Table 7.30.

Table 7.30 Summary of PFAS groundwater results at Runway 13/31 and western Base boundary



Drinking Water



PFOS 0.13 – – 198 (MW246) MW056, MW057, MW112, MW245, MW246

PFHxS – – – 259 (MW245) NA

Sum of PFOS & PFHxS

– 0.07 0.7 319 (MW245) MW056, MW057, MW102, MW104, MW112, MW245,

MW246

PFOA 220 0.56 5.6 21.0 (MW245) MW112, MW245, MW246

A summary of the groundwater results for Mount St John (MW230, MW234, MW235 and MW255) is presented in Table 7.31.

Table 7.31 Summary of PFAS groundwater results at Mount St John


Freshwater 95% Species

Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 0.54 (MW230) MW230, MW255

PFHxS - – – 0.80 (MW230) NA

Sum of PFOS & PFHxS

– 0.07 0.7 1.34 (MW230) MW230, MW234, MW235, MW255

PFOA 220 0.56 5.6 0.171 (MW235) NA


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A summary of the groundwater results for Fuel Farm 2 NQ0099 (MW005, MW046, MW081 and MW090) is presented in Table 7.32.

Table 7.32 Summary of PFAS groundwater results at Fuel Farm 2 NQ0099



Drinking Water



PFOS 0.13 – – 1,800 (MW081) MW005, MW046, MW081, MW090

PFHxS – – – 3,320 (MW081) NA

Sum of PFOS & PFHxS

– 0.07 0.7 5,120 (MW081) MW005, MW046, MW081, MW090

PFOA 220 0.56 5.6 146 (MW081) MW005, MW046, MW081

A summary of the groundwater results for the fire station NQ0055, former fire training area NQ0107 and surrounding area (MW015, MW016, MW021, MW054, MW055, MW109, MW110, MW138, MW139, MW250 and MW251) is presented in Table 7.33.

Table 7.33 Summary of PFAS groundwater results at fire station NQ0055, fire training ground NQ0107 and surrounds



Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 1,660 (MW139) MW015, MW016, MW021, MW054, MW055, MW109, MW110, MW138, MW139,

MW250, MW251

PFHxS – – – 2,580 (MW015) NA

Sum of PFOS & PFHxS

– 0.07 0.7 3,540 (MW015) MW015, MW016, MW021, MW054, MW055, MW109, MW110, MW138, MW139,

MW250, MW251

PFOA 220 0.56 5.6 86.3 (MW015) MW015, MW016, MW021, MW054, MW055, MW109, MW110, MW138, MW139,

A summary of the groundwater results for 5 AVN (MW009, MW038, MW043, MW114, MW125, MW142, MW247, MW248 and MW249) is presented in Table 7.34.


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Table 7.34 Summary of PFAS groundwater results at 5 AVN



protection

Drinking Water



PFOS 0.13 – – 1,510 (MW248) MW009, MW038, MW043, MW114, MW125, MW142, MW247, MW248, MW249

PFHxS – – – 727 (MW248) NA

Sum of PFOS & PFHxS

– 0.07 0.7 2,240 (MW248) MW009, MW038, MW043, MW114, MW125, MW142, MW247, MW248, MW249

PFOA 220 0.56 5.6 61 (MW248) MW038, MW043, MW114, MW125, MW247, MW248

A summary of the groundwater results for 38 SQN and domestic area of the Base (MW006, MW036, MW049, MW061, MW063, MW224 and MW232) is presented in Table 7.35.

Table 7.35 Summary of PFAS groundwater results at 38 SQN and the domestic area


Freshwater 95% species protection

Drinking water

Recreational water Maximum Concentration

Samples with exceedances

PFOS 0.13 – – 28.3 (MW063) MW006, MW036, MW049, MW061, MW063, MW224,

MW232

PFHxS – – – 15.3 (MW063) NA

Sum of PFOS & PFHxS

– 0.07 0.7 43.6 (MW063) MW006, MW036, MW049, MW061, MW063, MW224,

MW232

PFOA 220 0.56 5.6 1.20 (MW063) MW049, MW061, MW063

A summary of the groundwater results for the former fire training ground – NQ0054 and Fuel Farm 1 – NQ0052 (MW013, MW026, MW033, MW034, MW051, MW116, MW118, MW120, MW126 and MW129) is presented in Table 7.36.


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Table 7.36 Summary of PFAS groundwater results at fire training ground NQ0054 and Fuel Farm 1 NQ0052



Drinking Water

Recreational Water



PFOS 0.13 – – 342 (MW126) MW013, MW026, MW033, MW034, MW051, MW116, MW118, MW126, MW129

PFHxS – – – 81.8 (MW126) NA

Sum of PFOS & PFHxS

– 0.07 0.7 424 (MW126) MW013, MW026, MW033, MW034, MW051, MW116, MW118, MW120, MW126,

MW129

PFOA 220 0.56 5.6 16.1 (MW126) MW013, MW033, MW116, MW120, MW126, MW129

A summary of the groundwater results for the Ingham Road sports fields (MW226 - MW229) is presented in Table 7.37.

Table 7.37 Summary of PFAS groundwater results at Ingham Road sports fields



Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 0.124 (MW229) NA

PFHxS – – – 0.16 (MW227) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.215 (MW229) MW226, MW227, MW228, MW229

PFOA 220 0.56 5.6 0.0056 (MW229) NA

7.6.2 OFF-BASE

A summary of the groundwater results for the Town Common (MW201 – MW208) is presented in Table 7.38.

Table 7.38 Summary of PFAS groundwater results at the Town Common



Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 0.06 (MW208) NA

PFHxS – – – 4.54 (MW206) NA

Sum of PFOS & PFHxS

– 0.07 0.7 4.54 (MW206) MW206, MW208

PFOA 220 0.56 5.6 0.03 (MW206) NA


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A summary of the groundwater results for Pallarenda and Cleveland Bay (MW209 – MW211, MW233, MW252 and MW253) is presented in Table 7.39.

Table 7.39 Summary of PFAS groundwater results at Pallarenda and Cleveland Bay



Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 0.22 (MW209) MW209

PFHxS – – – 0.22 (MW209) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.44 (MW209) MW209, MW211

PFOA 220 0.56 5.6 0.02 (MW209) NA

A summary of the groundwater results for the former Rowes Bay landfill (MWRB1, MWRB2, MWRB3 and MWRB5) is presented in Table 7.40.

Table 7.40 Summary of PFAS groundwater results at former Rowes Bay landfill



Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 0.1 (MWRB1) NA

PFHxS – – – 0.07 (MWRB5) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.14 (MWRB5) MWRB1, MWRB5

PFOA 220 0.56 5.6 0.0021 (MWRB3)

NA

A summary of the groundwater results for Rowes Bay (MW212, MW213 and MW264) is presented in Table 7.41.

Table 7.41 Summary of PFAS groundwater results at Rowes Bay



Drinking Water

Recreational Water



PFOS 0.13 – – 0.0438 (MW264) NA

PFHxS – – – 0.904 (MW264) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.948 (MW264) MW264

PFOA 220 0.56 5.6 0.017 (MW264) NA


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A summary of the groundwater results for Belgian Gardens (MW214 – MW216, MW256, MW261 and MW269) is presented in Table 7.42.

Table 7.42 Summary of PFAS groundwater results at Belgian Gardens


Freshwater 95%

Species Protection

Drinking Water

Recreational Water



PFOS 0.13 – – 0.19 (MW216) MW216

PFHxS – – – 0.38 (MW216) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.57 (MW216) MW214, MW216, MW256

PFOA 220 0.56 5.6 0.0118 (MW256) NA

A summary of the groundwater results for Garbutt (MW217 – 223, 225, MW236, MW257 – MW260, MW263, MW266 – MW270) is presented in Table 7.43.

Table 7.43 Summary of PFAS groundwater results at Garbutt



Protection

Drinking Water

Recreational Water




MW267

PFHxS – – – 5.25 (MW222) NA

Sum of PFOS & PFHxS

– 0.07 0.7 14.5 (MW223) MW218, MW220, MW221, MW222, MW223, MW225, MW257, MW258, MW259, MW260, MW263, MW267

PFOA 220 0.56 5.6 0.37 (MW223) NA

A summary of the groundwater results for Bushland Beach (MW231), Mount St John (MW254 and MW262) and Bohle (MW237 – MW240) is presented in Table 7.44.


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Table 7.44 Summary of PFAS groundwater results at Bushland Beach, Mount St John and Bohle



Drinking Water

Recreational Water

Maximum Concentratio

n


PFOS 0.13 – – 0.285 (MW239) MW239, MW240

PFHxS – – – 0.137 (MW239) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.422 (MW239) MW237, MW238, MW239, MW240

PFOA 220 0.56 5.6 0.0386 (MW238)

NA

7.6.3 RESIDENTIAL PROPERTY EXTRACTION BORES

Samples were collected from 24 private groundwater extraction bores in the suburbs of Pallarenda, Rowes Bay, Belgian Gardens, West End and Garbutt. A summary of the groundwater results is presented in Table 7.45.

Table 7.45 Summary of PFAS groundwater results in residential property extraction bores



Drinking Water

Recreational Water



PFOS 0.13 – – 0.556 (BW015) BW015, BW030

PFHxS – – – 1.84 (BW030) NA

Sum of PFOS & PFHxS

– 0.07 0.7 2.07 (BW030) BW006, BW015, BW030

PFOA 220 0.56 5.6 0.0895 (BW030) NA

The locations of these samples are not shown on the Figures in Appendix A to deidentify property owners bores for privacy purposes.

One sample was collected from a swimming pool that the residents identified had been historically topped up with groundwater by the previous owners. The sample returned PFOS+PFHxS and PFOA concentrations above the detection limit but below the nominated ILs (0.0019 µg/L for both species).

7.6.4 COMMERCIAL PROPERTY EXTRACTION BORES AND MONITORING WELLS

Samples were collected from four commercial groundwater extraction bores and 18 commercial groundwater monitoring wells in the suburb of Belgian Gardens and Garbutt. A summary of the groundwater results is presented in Table 7.46.


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Table 7.46 Summary of PFAS groundwater results in commercial property extraction bores



Drinking Water

Recreational Water




MW460

PFHxS – – – 3. 91 (MW460) NA

Sum of PFOS & PFHxS

– 0.07 0.7 8.25 (MW457) MW405, MW414, MW415, MW437, MW439, MW455, MW456, MW457, MW459,

MW460, MW463

PFOA 220 0.56 5.6 0.39 (MW457) NA

All commercial property owners requested that their property details be deidentified for privacy reasons and the sample locations are not shown on the figures in Appendix A.

7.6.5 TOP ASSAY

TOP assay was undertaken on eight selected groundwater samples (approximately 1 in 20 of samples collected). TOP assay is used to indicate the potential for degradation of non-reported PFAS to further contribute to PFAS impact in the future.

It is noted within the industry that there are limitations with TOP assay assessment and the practicality of interpreting the results is not well understood.

The locations that had TOP assay undertaken during the DSI (WSP 2018a) were selected for analysis in Seasonal Monitoring Report 1 to provide an indication of whether the potential presence of PFAS precursor compounds has changed between sampling events.

Groundwater samples were prepared in the laboratory (ALS) by extract incubation with potassium persulfate and sodium hydroxide at 85°C for six hours as per the method described in Houtz and Sedlak (2012). Samples were then neutralised and analysed for the full suite of PFAS compounds. The Seasonal Monitoring Report 1 results are presented and compared in Tables 10 to 12, Appendix B.

The sum of perfluoralkane carboxylic acids (PFCA) post-TOP assay ranged from - 61% lower to 1,219% higher than the sum of PFCA in the conventional PFAS analysis, with the majority of this increase being PFHxA and increases in PFBA and PFPeA. All samples, except MW265, showed an increase in the sum of PFCAs, indicating a potential for the presence of precursor compounds in groundwater at the Base.

The >1,000% increase in the sum of PFCAs at MW126 suggests the presence of significant unidentified precursors in the groundwater at this location. However, the concentrations of other PFAS such as PFOS and PFHxS show a similar increase in this sample. The TOP assay result from January 2018 (WSP 2018a) showed a sum of PFCA increase of 68%, with a sum of PFCA of 360–380 µg/L, which is an order of magnitude lower than the sum of PFCA returned from the post TOPA assay in April 2018 (2,526 µg/L). It is considered that the April 2018 post TOP assay result for MW126 may be a statistical outlier.

Whilst all but one of the TOP assays results showed an increase >40% of PFCAs, excluding MW126, the absolute concentrations of the increase ranged from 1.83 µg/L to 631 µg/L, which comprised approximately 10–15% of the sum of PFHxS and PFOS in the same sample. Therefore, although precursors maybe present in groundwater at the Base, they are considered of minor consequence when assessing groundwater impacts in the IA, as the addition of potential


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precursor concentrations to the current PFOS + PFHxS concentrations does not change the identified level of impact against the investigation criteria. The relatively minor concentrations of PFAS precursors in most groundwater samples at the Base suggests that the PFAS is likely aged and in a weathered state and much of the oxidisable precursors that may have previously existed in the soils have been oxidised.

Excluding MW126, the largest increase in PFCA concentrations post TOP assay was observed in MW081, which was also the case in the DSI (WSP 2018a). MW081 is located at Fuel Farm 2 (NQ0099), where there is no record of fire training activities.

TOP assay does not give an indication of the rate of degradation of PFAS precursors and the rate of degradation in the natural environment may be slow and take years for significant increases in PFAS concentrations to occur.

7.6.6 HYDROGEOCHEMISTRY

Groundwater across the IA (i.e. both on- and off-Base) was analysed for major cations (calcium, magnesium, potassium and sodium) and major anions (chloride, sulfate and carbonate/bicarbonate) during the post-wet season monitoring event, to assist in understanding groundwater chemistry and whether any distinct groundwater facies could be identified in the IA. The Seasonal Monitoring groundwater geochemistry results are presented in Table 6, Appendix B and are summarised in Table 7.47.

Table 7.47 Summary of groundwater geochemistry, IA

ANALYTE CONCENTRATION RANGE (mg/L)

Bicarbonate alkalinity as CaCO3 <1 – 1,230

Chloride 17 – 52,600

Sulfate as SO42- <1 – 11,700

Calcium 1 – 1,120

Magnesium <1 – 5,190

Potassium <1 – 614

Sodium 8 – 27,700

The groundwater ranges from very fresh to hypersaline. The major ion characteristics of groundwater samples collected from on-Base and off-Base wells are shown on the piper diagrams in Figure 7.1 and Figure 7.2, respectively. A piper diagram is a graphical representation of the relative concentrations of major ions (Ca2+, Mg2+, Na+, K+, Cl-, HCO3

- and SO4

2-), and is used to distinguish the chemical profile of major water types.


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Figure 7.1 Piper diagram for on-Base wells

On-Base groundwater is dominated by the major ions sodium and chloride with a distinct trend towards bicarbonate. Although the wells with the highest bicarbonate influence are generally located in the south-eastern section of the Base (38 SQN and fire training ground NQ0054) the chemical trend is not purely driven by location, as only approximately half of the wells in this area show elevated bicarbonate.


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Figure 7.2 Piper diagram for off-Base wells

Various trends are visible in the off-Base groundwater. Groundwater from Garbutt and Bohle is similar to on-Base groundwater, being sodium/chloride dominated, although the strong bicarbonate trend evident in the on-Base data is not present in the off-Base data. Groundwater from the private bores is mostly from the coastal sand dune hosted aquifer and show higher concentrations of calcium than the on-Base wells. The wells located in the Town Common show a distinct sulfate influence, which may be related to sulphide-rich clay soils. The Rowes Bay wells show variable hydrochemistry, indicating possible mixing between the three different groundwater facies.

Comparison of EC between the DSI investigation and the post wet-season sampling showed a decreased EC in 67% of the monitoring wells. However, a third of the wells returned a higher EC than the dry season result, and no definite trend was evident in any of the monitoring areas on- or off-Base.

Town Common

Rowes Bay

Garbutt

Bohle

SO4Mg

HCO3+CO3Na + K

Cl

Cl + SO4 Ca + Mg

Cations Anions


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7.7 SURFACE WATER ANALYTICAL RESULTS

7.7.1 DISCHARGE SAMPLING

Surface water samples were collected from three on-Base locations (SW132, SW123 and SW131) and one off-Base locations (SW102) between 1 and 5 March 2018. SW102 was adjacent to a running pump at the time of discharge sampling.

SW123 is located at the discharge point on the western boundary of the Base, which discharges surface water and stormwater runoff from 5 AVN. SW131 is located to the west of the OLAs on the wetland that discharges into the Town Common to the north-west of the Base. This drainage system collects surface water runoff from Fire Station NQ0055, former fire training area NQ0107, Fuel Farm 2 NQ0099, former fire training area NQ106 and the northern half of Runway 13/31. SW102 is located off-Base immediately downstream of the discharge pump on the northern boundary of the Base. Surface water runoff from former fire training area NQ105 and parts of Runway 01/19 is discharges at this location into the Three Mile Creek catchment. SW132 is located at the point where surface water runoff and stormwater from the south-eastern section of the Base discharges into the Mundy Creek catchment. Surface water runoff from the former fire training area NQ0054, Fuel Farm 1 NQ0052 and the former cadet training ground discharges at this location.

All surface water samples were analysed for ultra-trace 28 PFAS suite. Selected samples were analysed additionally for turbidity, TDS, TSS, ferrous iron, metals (Al, Fe, Mn), TOC, BOD and COD.

A summary of the discharge surface water results (SW102, SW123, SW131 and SW132) is presented in Table 7.48.

Table 7.48 Summary of PFAS discharge surface water results



Drinking water

Recreational water Maximum concentration

Samples with exceedances

PFOS 0.13 – – 35.6 (SW132) SW102, SW123, SW131, SW132

PFHxS – – – 23.4 (SW123) NA

Sum of PFOS & PFHxS

– 0.07 0.7 50.3 (SW132) SW102, SW123, SW131, SW132

PFOA 220 0.56 5.6 5 (SW132) SW123, SW132

In summary:

— concentrations of PFAS increased and plateaued with time during the discharge event, with concentrations in SW123 increasing significantly on the third day of sampling

— PFOS had the highest concentrations in surface waters and exceeded ANZECC PFAS freshwater 95% species protection criteria (HEPA 2018) in all samples

— PFHxS was detected where PFOS was detected at lower concentrations — PFOS+PFHxS exceeded drinking water HBGVs in all samples and recreational HBGVs in all but the first two

samples collected from SW102 — PFOA was detected where PFOS was detected with one exception, and always at lower concentrations; drinking

water guidelines were exceeded in two samples collected from SW123 and all four samples collected from SW132 — the compounds PFDA, PFDoDA, PFTeDA, PFTrDA, MeFOSA, MeFOSAA, EtFOSA, MeFOSE, EtFOSE,

EtFOSAA, 4:2 FTS and 10:2 FTS were not detected in surface water during the investigation.


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7.7.2 POST-WET SEASON SURFACE WATER SAMPLING

Surface water samples were collected from 51 locations between 9 and 20 April 2018.

12 locations were associated with the co-located biota sampling points assessed in the DSI (WSP 2018a). Twenty surface water sampling locations were on-Base and 31 were off-Base.

The surface water samples were analysed for either the standard or ultra-trace PFAS analytical suite (Section 1.5.3), major anions and cations, with selected samples also analysed for turbidity, total suspended solids, minor cations and anions, aluminium, ferrous iron, manganese, BOD, COD and a filtered 28 PFAS suite. The surface water analytical results are presented in Table 8, Appendix B and shown on Figures 17 to 19 in Appendix A.

Summaries of the results for surface water sampling against the Tier 1 Screening criteria detailed in Section 6.3 are tabulated in the sections below for each of the on-Base (Section 0) and off-Base areas of interest (Section 7.7.2.2). Exceedances of the nominated ILs are shown in the tables as bold text.

In summary:

— PFOS was the most commonly detected PFAS and had the highest concentrations in surface waters in 60% of samples

— PFHxS was generally detected where PFOS was detected, and had the highest concentrations in surface waters in 40% of samples

— PFOA was usually detected where PFOS was detected, but always at lower concentrations — other species of PFAS were only detected when PFOS and PFHxS were detected, and generally only when PFOS

and PFHXs were elevated — the compounds PFDoDA, PFTrDA, PFTeDA, MeFOSA, EtFOSA, MeFOSE, EtFOSE, MeFOSAA, EtFOSAA,

4:2 FTS and 10:2 FTS were not detected in surface water during the investigation — eighteen exceedances of drinking water HBGVs and 16 exceedances of ecological ILs were detected on the Base;

and — twenty exceedances of drinking water HBGVs and 14 exceedance of ecological ILs were detected off-Base in

Garbutt (up-gradient), Mundy Creek catchment, Three Mile Creek catchment, Town Common and the Bohle River.

The composition of PFAS compounds in surface water is generally similar to the composition of PFAS in groundwater.

7.7.2.1 ON-BASE

A summary of the on-Base surface water results (SW001A, SW010S, SW012, SW013, SW015, SW016, SW019, SW020, SW039, SW101, SW102, SW103, SW104, SW112, SW123, SW124, SW125, SW126, SW131, SW132) is presented in Table 7.49.

Table 7.49 Summary of PFAS on-Base surface water results



Drinking Water



PFOS 0.13 – – 141 (SW039) SW001A, SW010S, SW012, SW013, SW015, SW019, SW039, SW101, SW102, SW103, SW123, SW,124, SW125, SW126, SW131,

SW132

PFHxS – – – 314 (SW039) NA


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Drinking Water



Sum of PFOS & PFHxS

– 0.07 0.7 455 (SW039) SW001A, SW010S, SW012, SW013, SW015, SW016, SW019, SW039, SW101, SW102, SW103, SW104, SW112, SW123, SW,124, SW125, SW126, SW131,

SW132

PFOA 220 0.56 5.6 14.1 (SW039) SW001A, SW019, SW039, SW123, SW132

7.7.2.2 OFF-BASE

A summary of the off-Base up-gradient surface water (SW014, SW017, SW120, SW127, SW128) and down gradient surface water (SW130) results are presented in Table 7.50. Up-gradient samples were obtained from Garbutt (Louisa Creek and Peewee Creek).

Table 7.50 Summary of PFAS off-Base upgradient (Garbutt) surface water results



Drinking Water



PFOS 0.13 – – 0.1 (SW017, SW120)

NA

PFHxS – – – 0.15 (SW120) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.25 (SW120) SW017, SW120,

PFOA 220 0.56 5.6 0.04 (SW120) NA


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A summary of the off-Base downgradient (Mundy Creek catchment) surface water results (SW108, SW109, SW113, SW114, SW115, SW116, SW117, SW118, SW208) is presented in Table 7.51.

Table 7.51 Summary of PFAS off-Base downgradient Mundy Creek catchment surface water results



Drinking Water

Recreational Water



PFOS 0.13 – – 18.4 (SW117) SW108, SW109, SW113, SW114, SW115, SW116, SW117, SW118, SW208

PFHxS – – – 13.9 (SW117) NA

Sum of PFOS & PFHxS

– 0.07 0.7 32.3 (SW117) SW108, SW109, SW113, SW114, SW115, SW116, SW117, SW118, SW208

PFOA 220 0.56 5.6 1.88 (SW117) SW117

A summary of the off-Base downgradient (Three Mile Creek catchment) surface water results (SW101, SW102, SW107, SW210) is presented in Table 7.52.

Table 7.52 Summary of PFAS off-Base downgradient Three Mile Creek catchment surface water results



Drinking Water

Recreational Water



PFOS 0.13 – – 0.7 (SW102) SW101, SW102

PFHxS – – – 0.68 (SW102) NA

Sum of PFOS & PFHxS

– 0.07 0.7 1.38 (SW102) SW101, SW102, SW107, SW210

PFOA 220 0.56 5.6 0.0212 (SW101) NA

A summary of the off-Base downgradient (Town Common) surface water results (SW110, SW111, SW112, SW205, SW206, SW207) is presented in Table 7.53.

Table 7.53 Summary of PFAS off-Base downgradient Town Common surface water results



Drinking Water

Recreational Water



PFOS 0.13 – – 3.45 (SW110) SW110, SW111, SW112, SW205, SW207

PFHxS – – – 2.87 (SW110) NA

Sum of PFOS & PFHxS

– 0.07 0.7 6.32 (SW110) SW110, SW111, SW112, SW205, SW206, SW207

PFOA 220 0.56 5.6 0.23 (SW1110) NA


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A summary of the off-Base background (SW129, SW201, SW202) and downgradient (SW203, SW204) Bohle River catchment surface water results is presented in Table 7.54.

Table 7.54 Summary of PFAS off-Base background and downgradient Bohle River surface water results



Drinking Water

Recreational Water



PFOS 0.13 – – 0.125 (SW202) NA

PFHxS – – – 0.153 (SW202) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.278 (SW202) SW202

PFOA 220 0.56 5.6 0.0111 (SW202) NA

A summary of the off-Base background (Ross, Alligator, Stuart and Althaus Creek) surface water results (SW130, SW211, SW212, SW213) is presented in Table 7.55.

Table 7.55 Summary of PFAS off-Base background surface water results



Drinking Water

Recreational Water



PFOS 0.13 – – 0.165 (SW130) SW130

PFHxS – – – 0.0808 (SW130) NA

Sum of PFOS & PFHxS

– 0.07 0.7 0.246 (SW130) SW130

PFOA 220 0.56 5.6 0.0139 (SW130) NA

7.7.3 HYDROCHEMISTRY

All surface water samples across the IA (i.e. both on and off-Base) were analysed for major cations (calcium, magnesium, potassium and sodium) and major anions (chloride, sulfate and carbonate/bicarbonate) to assist in understanding hydrochemistry within the IA. The surface water results are presented in Table 8, Appendix B and are summarised in Table 7.56.

Table 7.56 Summary of surface water major ion chemistry


Carbonate alkalinity as CaCO3 <1 – 53

Hydroxide alkalinity as CaCO3 <1,000

Bicarbonate alkalinity as CaCO3 16– 408

Chloride 12 – 17,500

Sulfate as SO42- 2 – 2,610


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Calcium 2 – 397

Magnesium 2 – 1,370

Potassium 1 – 501

Sodium 10 – 10,100

The surface water in the IA ranges from very fresh to saline. Salinity generally increases towards the coast; however, some of the wetlands on the Base contained relatively high concentrations of chloride and sodium. Surface water on the Base was not flowing at the time of the post-wet season sampling event, which may have resulted in slightly elevated salinities through evaporation.

7.8 SEDIMENT ANALYTICAL RESULTS Sediment samples were collected from 55 locations, co-located with the surface water sampling locations (where sufficient sample was available), comprising 26 on-Base locations and 29 off-Base locations.

The sediment samples were analysed for the standard PFAS 28 analytical suite or super-trace suite (Section 1.5.3), major anions and cations and 1 in 20 samples were analysed for TOP assay.

As discussed in Section 7.2.2, some samples collected from grass-covered swales were logged as sediment but are considered more akin to soil samples, and have been considered as such for screening purposes.

The sediment analytical results are presented in Table 7, Appendix B and shown on Figures 20 to 22, Appendix A. Summaries of the results for sediment sampling are tabulated in the sections below for each of the on-Base (Section 7.8.1) and off-Base areas of interest (Section 7.8.2). As there are currently no sediment screening levels for PFAS in Australia, no exceedances of ILs have been shown in the tables.

In summary:

— PFOS was the most commonly detected PFAS and had the highest concentrations in sediment in all samples but one — PFHxS was generally detected where PFOS was detected, at lower concentrations in all cases but one — PFOA was usually detected where PFOS was detected, but always at lower concentrations — other species of PFAS were only detected when PFOS and PFHxS were detected, and generally only when PFOS

and PFHXs were elevated — PFBS, PFPeS, PFHpS, PFHxA and PFHpA were generally detected in impacted samples; other PFAS compounds

(PFDS, PFBA, PFPeA, PFNA, PFUnDA, FOSA, 8:2 FTS) were only detected in isolated sediment samples, usually the ones with the highest PFOS and PFHxS concentrations; and

— the compounds PFDA, PFDoDA, PFTeDA, PFTrDA, EtFOSE, EtFOSAA EtFOSA, MeFOSA, MeFOSE, MeFOSAA, 4:2/6:2 and 10:2 FTS were not detected in sediment during the investigation.

The composition of PFAS compound concentrations in sediments is generally similar to the composition of PFAS concentrations in surface water.

7.8.1 ON-BASE

A summary of the on-Base sediment PFAS results (SD001A, SD010S, SD012, SD013, SD015, SD016, SD019, SD020, SD021, SD024, SD025, SD039, SD101, SD102, SD103, SD104, SD123, SD124, SD126, SD131, SD301, SD302) is presented in Table 7.57.


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Table 7.57 Summary of PFAS on-Base sediment results

ANALYTE ANALYTICAL RESULTS (mg/kg)

Maximum Concentration Samples with Exceedances

PFOS 80.2 (SD024) NA

PFHxS 13.4 (SD024) NA

Sum of PFOS & PFHxS 93.6 (SD024) NA

PFOA 0.625 (SD024) NA

7.8.2 OFF-BASE

A summary of the off-Base up-gradient (Garbutt) sediment PFAS results (SD014, SD120, SD127, SD128) is presented in Table 7.58.

Table 7.58 Summary of PFAS off-Base up-gradient (Garbutt) sediment results



PFOS 0.0010 (SD127) NA

PFHxS <0.0002 NA


PFOA <0.0002 NA

A summary of the off-Base downgradient (Mundy Creek catchment) sediment PFAS results (SD108, SD109, SD113, SD114, SD115, SD116, SD117, SD118, SD121, SD208) is presented in Table 7.59.

Table 7.59 Summary of PFAS off-Base downgradient Mundy Creek catchment sediment results



PFOS 0.205 (SW113) NA

PFHxS 0.0384 (SW113) NA

Sum of PFOS & PFHxS 0.243 (SW113) NA

PFOA 0.0033 (SW113) NA

A summary of the off-Base downgradient (Three Mile Creek catchment) sediment PFAS results (SD101, SD102, SD107, SD210) is presented in Table 7.60.

Table 7.60 Summary of PFAS off-Base downgradient Three Mile Creek catchment sediment results



PFOS 0.0192 (SD102) NA

PFHxS 0.0017 (SD102) NA


PFOA <0.0002 NA


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A summary of the off-Base downgradient (Town Common) sediment PFAS results (SD110, SD111, SD112, SD205, SD206, SD207) is presented in Table 7.61.

Table 7.61 Summary of PFAS off-Base downgradient Town Common sediment results



PFOS 0.096 (SD110) NA

PFHxS 0.0094 (SD110) NA


PFOA 0.0009 (SD110) NA

A summary of the off-Base background (SD129, SD201, SD202) and downgradient (SD203, SD204) Bohle River catchment sediment PFAS results is presented in Table 7.62.

Table 7.62 Summary of PFAS off-Base background and downgradient Bohle River catchment sediment results



PFOS 0.0012 (SD202) NA

PFHxS <0.0002 NA


PFOA <0.0002 NA

A summary of the off-Base background (Alligator, Stuart and Althaus Creek) sediment PFAS results (SD211, SD212, SD213) is presented in Table 7.63.

Table 7.63 Summary of PFAS off-Base background sediment results



PFOS 0.0022 (SD213) NA

PFHxS <0.0002 NA


PFOA <0.0002 NA

7.8.3 TOP ASSAY

TOP assay was undertaken on three selected sediment samples (approximately 1 in 10 of samples collected) during the Seasonal Monitoring investigation.

It is noted within the industry that there are limitations with TOP assay assessment and the practicality of interpreting the results is not well understood.

Samples were selected to provide a range of detected PFAS concentrations (PFOS concentrations ranged from 0.0194 mg/kg to 2.75 mg/kg) and an even geographical distribution across the IA in order to investigate the potential presence of PFAS compounds not included in the standard 28 species analytical suite. Sediment samples were prepared and analysed in the laboratory (ALS) as per the methodology used on soils described in Section 7.5. The results are presented and compared in Table 10, Appendix B.


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The sum of PFCA post-TOP assay ranged from 76% to 552% higher than the sum of PFCA in the conventional PFAS analysis, with the majority of this increase being PFHxA. These results showed an increase in the sum of PFCAs >10%, indicating a potential for the presence of precursor compounds in sediments at the Base.

Whilst the three TOP assays results showed an increase >10% of PFCAs, the absolute concentrations of the increase ranged from 0.0089 mg/kg to 0.0685 mg/kg, which comprised approximately 50 to 100% of the sum of PFHxS and PFOS in the same sample. Therefore, although precursors maybe present in sediments at the Base, they are considered of minor consequence when assessing current sediment impacts in the IA. The relatively minor concentrations of PFAS precursors at the Base suggests that the PFAS is likely aged and in a weathered state and much of the oxidisable precursors that may have previously existed in the sediments have been oxidised.

7.9 BIOTA RESULTS Seven biota (fruit and vegetable) samples were collected from three residences in Garbutt and Pallarenda. Biota results have not been shown on any figures to protect the resident’s privacy. Results are presented in Table 9, Appendix B, with laboratory certificates contained in Appendix E.

No PFAS was detected in any fruit sample and PFOS was only detected in one sample of spinach at a concentration of 0.002 mg/kg. These results were used in the HHRA (WSP 2018b), which identified a low and acceptable health risk associated with the ingestion of home-grown fruit and vegetables in the IA.

7.10 QUALITY ASSURANCE AND QUALITY CONTROL The QA and QC program implemented for the investigation was completed in accordance with the seven-step DQO process as described in Section 1.5.3. In total, 374 primary soil, sediment, surface water, swimming pool, groundwater and biota samples, 42 intra-laboratory duplicates and 28 inter-laboratory duplicates were analysed. A review of the work undertaken against the DQOs was demonstrated by reference to the DQIs (Appendix C). Field duplicate and triplicate comparisons are tabulated in Table 1 and Table 2, Appendix C.

Appendix C documents isolated non-conformances under the analysis requirement as follows:

— Holding times – Six sediment laboratory work orders had holding time breaches for soil pH, EC and organic matter and ten water laboratory work orders had holding time breaches for pH, turbidity, major cations, reactive phosphorus and BOD.

— Duplicate reproducibility – relative percent differences (RPDs) outside of acceptable range for blind intra laboratory and split inter laboratory duplicates.

— Analytes with holding breaches limited to soil pH, EC and organic matter and water pH, turbidity, major cations, reactive phosphorus and BOD.

— Sediment breaches were a result of laboratory delays outside control of WSP.

— Water holding breaches were due to the short holding times of the analytes in question and the distance between the IA and the analytical laboratory. Samples collected on Friday were not able to be extracted within the holding times. No holding time breaches for contaminants of concern, and are not considered to have impacted the results of the investigation.

A detailed analysis of the parent/duplicate comparative results was undertaken to identify whether the differences between parent and blind and/or split duplicate may have affected the findings of the investigation. Results were interrogated to identify occasions where the parent exceeded the nominated criteria but one or both of the duplicates did not (false positive) or where the parent was below the nominated criteria but one or both of the duplicates were (false negative).


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In the case of soil and sediment analyses, there were no parent/duplicate pairs identified where the parent was below the nominated ILs, but the duplicate was above the guidelines for these analytes (i.e. a possible false negative). There were also no parent/duplicate pairs identified where the parent was above the ILs, but the duplicate was below the guidelines for these analytes (i.e. a possible false positive). The RPD non-compliances in the soil and sediment samples are not considered to have impacted the findings of the investigation.

The groundwater QA/QC data showed two parent/duplicate pairs samples where variability in results may lead to mis-interpretation against the guidelines. The fact that the detection level is less than half an order of magnitude below some of the nominated criteria has exacerbated this.

MW205/QC1MW_180413_02 returned concentrations of PFOS + PFHxs below the LOR but returned a concentration of 0.08 µg/L in the split duplicate, above the drinking water criteria. This may represent a false negative in the parent sample. The difference is likely due to heterogeneous distribution of PFAS in the groundwater coupled with the low concentrations of the samples and differences in laboratory analyses. In the DSI (WSP 2018a), this well returned a similar concentration to that returned by the split duplicate, which is therefore considered to be the relevant result in this case. Future analysis from this well will benefit from ultra-trace analysis.

MW214 returned a concentration of 0.102 µg/L for PFOS + PFHxS, which is above the nominated drinking water IL (HEPA 2018). The split duplicate returned a PFOS + PFHxS concentration of 0.051 µg/L, below the drinking water IL of 0.07 µg/L. This may represent a false positive in the parent sample. The difference is likely due to heterogeneous distribution of PFAS in the groundwater coupled with the low concentrations of the samples and differences in laboratory analyses. The parent and blind duplicate samples are considered to be the relevant results in this case.

The surface water QA/QC data showed several parent / duplicate pairs samples where variability in results may lead to mis-interpretation against the guidelines. The fact that the detection level is less than half an order of magnitude below some of the nominated criteria has exacerbated this.

SW015/QC2SW_180418_01 returned concentrations of PFOS + PFHxs above the recreational water criteria in the parent (0.856 µg/L) and split duplicate (0.89 µg/L) but below the recreational water IL in the blind duplicate. This may represent a false positive in the parent sample. The difference is likely due to heterogeneous distribution of PFAS in the water and differences in laboratory analyses. The parent and split duplicate samples are considered to be the relevant results in this case.

SW123_180302_F/QC1SW_180302 returned concentrations of PFOA below the drinking water criteria in the parent sample (0.107 µg/L) and blind duplicate (0.165 µg/L) but above the drinking water IL in the split duplicate (1.5 µg/L). This may represent a false negative in the parent sample. The difference may be due to inconsistent approaches by the laboratories, but may also be the result of assignation of incorrect primary to duplicate/triplicate pairs. These samples were proposed for filtration, which may not have occurred for the split duplicate. The parent/blind duplicate are considered to be the relevant results in this case. PFOS + PFHxS concentrations were above the ILs in the parent and duplicate samples so the CSM is unaffected by this RPD difference.

SW123_180305_F returned a concentrations of PFOA above the drinking water criteria in the parent sample (2.71 µg/L) but below the drinking water IL in the split duplicate (0.15 µg/L). This may represent a false positive in the parent sample. The difference may be due to inconsistent approaches by the laboratories, but may also be the result of assignation of incorrect primary to duplicate/triplicate pairs. These samples were proposed for filtration, which may not have occurred for the parent. The split duplicate is considered to be the relevant result in this case. PFOS + PFHxS concentrations were above the ILs in the parent and duplicate samples so the CSM is unaffected by this RPD difference.

SW123_180302 and SW123_180305 and associated duplicates were sampled during high flow sampling. The poor reproducibility in these QA/QC sets was not replicated during normal sampling (excepting SW119 and SW128 discussed below), and may be related to water heterogeneity during high flow flood events. Future sampling events during high flow events may need to take this into account. The poor reproducibility in the discharge sampling QA/QC duplicate sets are not considered to make a material difference to the investigation findings as all values are well over the relevant assessment criteria. The objective of the discharge sampling was to gain an understanding of concentrations


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leaving site during flow events to test the conceptualisation of surface water being the main mechanism for PFAS leaving the base. Results support this theory despite the elevated RPDs of QA/QC pairs.

SW119_180420 returned concentrations of PFOS + PFHxS and PFOA well above the drinking water criteria in the parent sample but below the criteria in the blind duplicate QC1SW_180420_02. Conversely, SW128_180420 returned concentrations of PFOS + PFHxS and PFOA below the drinking water criteria in the parent sample but well above the criteria in the blind duplicate QC1SW_180420_01. This may represent a false positive in SW119 and a false negative in SW128. It is considered possible that the blind duplicates for these two samples were miscorrelated as the results for SW119 are similar to QC1SW_180420_01 and the results for SW128 are similar to QC1SW_180420_02; all samples were collected on the same day. Given the results of these locations in the DSI (WSP 2018a) sampling event, the parent samples are considered to be the relevant results.

In summary, the non-conformances for RPDs in the QA/QC samples for the investigation have not resulted in any changes to the findings of the Seasonal Monitoring investigation or CSM.

The small number (~0.003%) of detects in field, rinsate and trip blanks should be taken with consideration of the overall number of samples and non-detects. Most of the detects were marginally above detection limits; however, one rinsate blank was over an order of magnitude above the LOR. In-field SOPs, including specific procedures to minimise potential contamination of samples by PFAS, were adhered to during the investigation; therefore no obvious explanation for the detection of PFAS in some blanks is available. The presence of PFAS in some blank samples infers the possibility of false detects in groundwater and surface water samples. The worst case scenario for the investigation in this event is that clean samples return PFAS detects.

In consideration of the nature and magnitude of the variations as detailed above, it was considered that the results and overall conclusions of the Seasonal Monitoring Report 1 had not been significantly affected by the identified non-conformances in sampling procedures and analytical processes.

TOP ASSAY QA/QC

In addition to the DQO process discussed above, the PFAS NEMP (HEPA 2018) prescribes the following QA/QC checks for TOP assay analysis:

— The total PFAS concentration post-TOPA should be greater or equal to the total PFAS concentration pre-TOPA, which signifies no material losses observed in preparation steps, noting a decrease of up to 10% might be expected due to normal analytical variability.

— The sum of PFCA post-TOPA should be equal to or greater than the sum of PFCA pre-TOPA, which signifies any precursors being converted to PFCA products.

— The sum of perfluoralkane sulfonic acids (PFSA) post-TOPA should approximate the sum of PFSA pre-TOPA, signifying that precursors did not convert to PFSA products.

— For a full oxidation, no PFAA precursors (e.g. 6:2 FTS, FOSA) are detectable post oxidation, signifying complete oxidation.

— For situations where a near complete oxidation is acceptable, minimal perfluoroalkyl acids (PFAA) precursors are detectable post oxidation signified by:

— for aqueous samples, sum of [PFAA precursors] divided by sum of [Total PFAS] <5% — for soil samples, sum of [PFAA precursors] divided by sum of [Total PFAS] <10%; and — noting greater leniency may be applied for samples where PFAS were detected ≤ 10 times LOR.

Post TOP assay sum of PFAS concentrations were lower than the conventional sum of PFAS concentration by >10% in three of eight groundwater samples and one of three surface water samples, with up to 78% less PFAS in soils and 50% less in surface water. Conversely, in sediment samples, post TOP assay sum of PFAS concentrations were up to 44% higher than the conventional PFAS analysis.


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One groundwater sample returned post TOP assay sum of PFCA concentrations >10% lower than the conventional PFAS sum of PFCA concentrations. None of the sediment or surface water samples returned post TOP assay sum of PFCA concentrations lower than the conventional PFAS sum of PFCA concentrations.

Post TOP assay sum of PFSA concentrations were >10% less than the conventional PFAS sum of PFSA concentrations in three of eight groundwater samples and one of three surface water samples, with up to 81% less in groundwater and 15% less in surface water. Conversely, post TOP assay sum of PFSA concentrations were >10% more than the conventional PFAS sum of PFAS concentrations in one groundwater sample pair (440%) and one sediment sample pair (50%).

No samples contained PFAS precursors in their post TOP assay analysis.

In summary, several soil and sediment samples showed anomalously decreased PFAS and PFSA concentrations post TOP assay; however, there were no precursor concentrations remaining post TOP assay. According to the laboratory (ALS, J Pickering 2017, pers comm., 1 November 2017), control samples have previously shown that under the conditions of TOP assay, PFSAs are stable and their concentrations should not decrease after the assay. As the laboratory collected separate sub-samples from the sample container to undertake the original sample and the TOP assay, sample heterogeneity may be responsible for the observed differences. ALS are aware that in actual field samples there may be certain situations where the presence of other oxidisable material (such as high organic carbon) changes the reaction mechanism leading to lower results after the assay (J Pickering 2017, pers comm., 1 November 2017). The mechanism is believed to be due to the oxidisable material competing for the hydroxyl radicals. The action of the remaining sulfate radicals can lead to chain shortening, yielding PFAS that will not be reported post-assay. ALS have found that certain foam preparations that contain organic materials as thickeners (xanthan gum) confirm this effect.

The QA/QC exceedances discussed above are considered of minor consequence when assessing impacts on the DSI Addendum, as the addition of potential precursor concentrations to the PFOS + PFHxS concentrations does not materially change the identified level of impact against the investigation criteria.


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8 DISCUSSION

8.1 NATURE AND EXTENT OF SOIL IMPACT Soil PFAS results are presented in Table 5, Appendix B and shown on Figure 12 to Figure 13, Appendix A.

PFOS and PFHxS were detected at higher concentrations and more frequently then PFOA; therefore, the sum of PFOS and PFHxS is selected as the indicator parameter for impact, which aligns with the available human health soil guidelines.

All soil sampled during the Seasonal Monitoring investigations reported detectable PFOS + PFHxS concentrations; however, human health guideline exceedances were only reported at three residences that irrigate lawns and gardens with groundwater. No on-Base samples returned PFOS + PFHxS above the HEPA 2018 public open space or commercial/industrial land use HBGVs.

PFOS + PFHxS was detected off-Base on three residences (two in Garbutt, one in Pallarenda) at concentrations above the soil residential HBGVs. PFOS was detected at these locations at concentrations above the ecological screening levels.

It should be noted that the focus of the Seasonal Monitoring soil investigations was to target gaps in the near surface soil database and to investigate soils at residences that irrigated lawns and gardens using groundwater with elevated PFAS.

Four samples collected from grass-covered swales were logged as sediment but are considered more akin to soil samples (SD023a, SD23b, SD23c and SD122) and are interpreted in this section.

8.1.1 ON-BASE SOURCE AREAS – SOIL IMPACTS

A summary of the soil screening results for the Base is provided in Table 8.1.

Table 8.1 Summary of on-Base soil screening results

BASE SOURCE AREA

SCREENING LEVEL

EXCEEDANCE?

NO. OF SAMPLES IN EXCEEDANCE OF INDUSTRIAL/

COMMERCIAL ECOLOGICAL ILS (TOTAL SAMPLE

NO. IN BRACKETS)

NO. OF SAMPLES IN EXCEEDANCE OF RESIDENTIAL HBGVS (TOTAL SAMPLE NO. IN

BRACKETS)

NO. OF SAMPLES IN EXCEEDANCE OF

INDUSTRIAL/ COMMERCIAL

HBGVS (TOTAL SAMPLE NO. IN

BRACKETS)

OLAs No 0 (3) NA 0 (3)

Fire training ground NQ0054

Yes 1 (1) NA 0 (1)

Ingham Road sports field*

No 0 (4) 0 (4) 0 (4)

* Soil results from Ingham Road sports fields were compared against public open space guidelines.

OLAs

Three surface soil samples were collected from the northern OLAs. These samples were located in grassed swales and were logged as sediments, but have been screened as soil samples. PFOS and PFHxS were detected in all samples; however, no exceedances of commercial/industrial HBGVs or ecological guidelines were reported. Although the PFAS concentrations are relatively low in these samples, their location in drainage channels indicates they likely provide a secondary source for surface water / groundwater PFAS impact to the Town Common.


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FORMER FIRE TRAINING AREA NQ0054

One sample (SD122) was analysed from the grassed swale that drains the former fire training area NQ0054. PFOS and PFHxS were detected in this sample, with concentrations of PFOS in exceedance of the nominated soil commercial/industrial ecological guidelines. However, the concentrations of PFOS+PFHxS were below human health guidelines.

The swale that the sample was collected from drains water from the former fire training area into the Mundy Creek catchment. Therefore, the soils are considered a secondary source of PFAS, providing a source for potential on-Base human health risk, and surface water/groundwater PFAS impact to the Mundy Creek catchment and Garbutt groundwater users.

INGHAM ROAD SPORTS FIELD

Four surface soil samples were analysed from the centre of the two playing fields at the Ingham Road sports field. These samples were collected to fill a data gap from the DSI (WSP 2018a) as the soil samples previously collected from this area were associated with monitoring well installation and were obtained from the edges of the playing fields and at depths of 0.5 mbgs or greater. A data gap existed with respect to PFAS concentrations in shallow surface soil.

PFAS was detected in all four samples, with no exceedances of the HEPA 2018 human health or ecological guidelines for public open space or industrial/commercial land use. The relatively low concentrations of PFAS in this area reflects the historic intermittent nature of AFFF use (reportedly annually for open day events).

The soils beneath the Ingham Road sports fields are considered to be a secondary source of PFAS, providing a source for surface water and groundwater PFAS impact to Peewee Creek; however, the relatively low concentrations of PFAS in the soils at this location suggest that the area is a relatively insignificant source in the context of the wider investigation at the Base.

8.1.2 OFF-BASE SECONDARY SOURCE AREAS – SOIL IMPACTS

The two soil samples (BH061 and BH062) collected from immediately east of the Base boundary in Garbutt returned PFOS + PFHxS concentrations below the residential HBGV (Section 7.5.2). Soil samples collected during the DSI (WSP 2018a) identified shallow soil impact in Fuel Farm 1 NQ0052, which was not delineated between this area and the residential suburb of Garbutt. The low PFAS concentrations in BH061 and BH062 have effectively delineated the on-Base shallow soil impact identified and the domestic area.

Thirty-one soil samples were collected from seven residences in Garbutt (three properties), Rowes Bay (two properties) and Pallarenda (two properties). The DSI (WSP 2018a) reported that one residence was regularly inundated with overflow from the channels that drain the south-eastern section of the Base and a sample was collected from this location to investigate whether the soils in their lawns had PFAS impact, potentially adsorbed from this water. The DSI (WSP 2018a) reported the other five residences irrigated their lawns and gardens with PFAS impacted groundwater, and as such, these properties were sampled to investigate whether shallow soils had been impacted by this activity.

Trace (<0.005 mg/kg) concentrations of PFOS were detected in near-surface soils collected from the residence that had been regularly flooded. Trace concentrations of PFAS below the investigation criteria were also detected in three of the residences that irrigated with groundwater (one in Garbutt, Pallarenda and Rowes Bay).

Three residences (one each in Garbutt, Rowes Bay and Pallarenda) returned PFOS+PFHxS concentrations above the residential HBGVs (maximum 0.573 mg/kg). The PFAS impact is considered to be a result of long-term irrigation with PFAS impacted groundwater, although biomagnification processes in the root zones of fruit trees may be contributing to the elevated PFAS concentrations in some soil samples. These exceedances have been considered in the HHRA (WSP 2018b).


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8.2 HYDROGEOLOGY

8.2.1 THICKNESS AND EXTENT OF LOCAL AQUIFERS

During the DSI (WSP 2018a), no evidence was observed to support the existence of a shallow perched aquifer in the top one to two metres at the Base, including in the review of historical groundwater investigations. It is considered likely that the interbedded clays, silts and sands form a connected, semi-confined aquifer across the Base, with a water depth of approximately 0.5 mbgl to 2.5 mbgl. It is likely this semi-confined aquifer is at least partially connected to the underlying fluvial sand and gravel-hosted aquifers, which are reported to be present at a depth of 5 mbgl to 10 mbgl (SKM 2008), but were not confidently identified in this investigation.

The clay/silt/sand aquifer was intersected across the whole IA which suggests that the unit extends across the entire coastal plain between the coastal sands and the outcropping granites and volcanics of Castle Hill, Mount Louisa and Many Peaks Range.

The sand-hosted aquifer in Cleveland Bay, Rowes Bay and Pallarenda runs parallel to the coast and thins both eastwards and westwards. The eastern extent of this aquifer is not known as it extends offshore beneath Cleveland Bay. The sand aquifer extends approximately 2 km inland in the Town Common and narrows to the south, extending approximately 1 km inland at the Base and 500 m inland at Rowes Bay and Belgian Gardens.

8.2.2 GROUNDWATER RECHARGE

The majority of the Base has a sandy/silty clay shallow sub-surface, which implies that both rainfall infiltration through the surface soil, and groundwater recharge would be slow.

Standing surface water covered several areas of the Base following the large rainfall event experienced in March 2018, with standing water also observed along the water front at Rowes Bay and Pallarenda at this time. This water receded very slowly, with large pools remaining across the Base throughout the five day discharge sampling event in March 2018, suggesting slow infiltration into the groundwater. However, groundwater levels recorded across the IA in the post-wet season groundwater sampling (April 2018) averaged 0.55 m higher than groundwater levels in the DSI (WSP 2018a). This conversely suggests that groundwater recharge is relatively rapid and that the permeability of the shallow soils is higher than that expected from the field observations.

Photos of standing water at each discharge sampling point and at Rowes Bay and Pallarenda during the discharge monitoring in March 2018 are presented in Appendix D.

8.2.3 GROUNDWATER ELEVATION FLUCTUATIONS

Groundwater levels at the Base are known to fluctuate with the dry and wet seasons, generally reaching a low point near the end of the year prior to the start of the wet season in November/December (SKM 2008). Monitoring wells that were gauged in multiple monitoring events during the dry season (August and December 2017 and January 2018) (WSP 2018a) showed variable water level changes, with the SWL increasing in some wells and decreasing in others between events (Table 1, Appendix B).

Standing groundwater levels across the IA were predominantly higher during the post-wet season GME in April 2018 than were encountered during previous monitoring events (WSP 2018a), with the average increase being 0.55 m. The groundwater increase varied by up to 0.6 m between wells located within the same area of the Base, indicating the magnitude of increase was variable across the Base with no discernible trends.

Two on-Base wells recorded a lower SWL during the post-wet season GME (MW121 and MW235). Both wells are located to the north-west of the Base in the direction of groundwater flow. Only one off-Base groundwater well had a lower SWL during the post-wet season GME compared to the DSI (August 2017). This well (MW439) is located to the north-east of the Base and reported a 0.49 m difference in SWL. The reason for the groundwater level decrease in these wells is not known but given the isolated nature of the anomalies, is not considered to impact on the CSM.


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8.2.4 SHALLOW GROUNDWATER/SURFACE WATER INTERACTION

The reported surface water and groundwater level elevations show that the groundwater was likely to be receiving from the surface waters at the time of the Seasonal Monitoring investigation. The drain on the western boundary of the Base at 5 AVN has an elevation of 3 mAHD, approximately 0.3 m higher that the groundwater levels in MW248, but approximately the same level as the groundwater in MW247. This suggests that in the wet season, groundwater daylights in this drainage channel.

Surface water elevations in the drains on the south-eastern boundary of the Base are approximately 0.2 m to 0.8 m higher than the groundwater levels in the underlying aquifer.

The surface water in the wetlands between the Base and the former Rowes Bay landfill have an elevation of approximately 2 mAHD, which is 0.2 m to 0.4 m higher than the monitoring wells located in the northern section of the Base (MW241 and MW242). The groundwater beneath the former Rowes Bay landfill has an elevation at approximately the same level as the surface water in the wetland to the west, indicating that groundwater from the dunes likely daylights in these wetlands.

The surface water elevations of the wetlands in the Town Common are at approximately 2 mAHD (Townsville City Council Townsville MAPS Premium), which is approximately equal to 0.4 m lower than the groundwater elevations in the adjacent monitoring wells (MW204 – MW207), indicating that during the wet season the surface water from the Town Common is likely connected to the shallow aquifer.

The surface water elevations of Mundy Creek and tributaries to the north of Garbutt upstream of tidal influence are at approximately 2 mAHD, which is approximately 0.1 m higher than the groundwater levels in that area (MW217 and MW218).

The lower reaches of Mundy Creek and associated wetlands are tidal and the surface water elevations are at or close to sea level. The groundwater elevation in monitoring wells MW212, MW213, MW214 and MW215 are approximately 0.8 m to 2.0 m higher than sea level, suggesting that the surface water may be gaining from the aquifer, especially during low tide. At the time of the post-wet season sampling event, surface water in Mundy Creek near MW216 was approximately 0.3 m lower than the groundwater elevation at MW216. Therefore, the transition between Mundy Creek losing to groundwater upstream and gaining from groundwater downstream was inferred to be between MW216 and MW217 at this time.

8.2.5 HYDRAULIC CONDUCTIVITY ESTIMATES

The hydraulic conductivity of groundwater beneath the Base and Rowes Bay landfill has been calculated by ERM (2005) and SKM (2008) using the results of slug tests that were conducted on a number of monitoring wells (Section 7.3.4). The average hydraulic conductivities derived from the tests were 1.55 x 10-7 m/sec (0.013 m/day) for the sandy/silty clays beneath the Base and approximately 1.35 x 10-5 m/sec (1.2 m/day) for the sands beneath the former Rowes Bay landfill.

The values for the sandy/silty clays are considered representative of the aquifers beneath Garbutt and the Town Common. The values for the sands at the former Rowes Bay landfill are considered representative of the sand dunes and swales of Rowes Bay, Cleveland Bay and Pallarenda.

Uncertainties exist in hydraulic conductivity values derived by slug testing due to aquifer heterogeneity and well construction issues; however, notwithstanding these uncertainties, the values above correspond to published values for similar geological material and are considered adequate to use for groundwater flow velocity calculation.


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8.2.6 ESTIMATING GROUNDWATER FLOW VELOCITY

The groundwater flow velocity of an aquifer can be calculated based on Darcy’s Law:

ν = Κ x (dh/dl)/ne

Where:

ν = the average linear groundwater velocity Κ = hydraulic conductivity dh/dl = horizontal hydraulic gradient or rise/run ne = effective porosity

The values used to derive the groundwater flow velocity for the silty/sandy clays found in the central and western areas of the Base were:

— Κ = 0.013 m/day (SKM 2008) — dh/dl = 0.001 m/m (calculated from the groundwater elevations in Section 7.3.2); and — ne = 0.05 – 0.15 (derived from literature values (Domenico and Schwartz 1990) for porosity of silty clay (lower

bound) and silty sand (upper bound) as per the logging descriptions and PSD results).

A groundwater velocity of approximately 0.03 m/year to 0.1 m/year has been calculated for the silty/sandy clay aquifer beneath the central and western areas of the Base.

The values used to derive the groundwater flow velocity for the silty/sandy clays found in the south-eastern area of the Base were:

— Κ = 0.32 m/day (SKM 2008) — dh/dl = 0.002 m/m (calculated from the groundwater elevations in Section 7.3.2); and — ne = 0.05 – 0.15 (derived from literature values (Domenico and Schwartz 1990) for porosity of silty clay (lower

bound) and silty sand (upper bound) as per the logging descriptions and PSD results).

A groundwater velocity of approximately 1.6 m/year to 4.7 m/year has been calculated for the silty/sandy clay aquifer beneath the central and western areas of the Base.

The values used to derive the groundwater flow velocity for the sand aquifer at Rowes Bay were:

— Κ = 1.2 m/day (SKM 2008) — dh/dl = 0.002 m/m (calculated from the groundwater elevations in Section 7.3.2); and — ne = 0.1 – 0.3 (derived from literature values (Domenico and Schwartz 1990) for porosity of fine (lower bound) to

medium (upper bound) grained sand as per the logging descriptions and PSD results).

A groundwater velocity of approximately 2.8 m/year to 8.8 m/year has been calculated for the sand aquifer at Rowes Bay.

Should the effective porosity in the silty/sandy clays or sands be higher than estimated, the groundwater flow velocity will be lower. Heterogeneities in the aquifers, especially sandy layers in the silty/sandy clays, may have higher flow velocities than those calculated above, and may act as preferential pathways for groundwater.

Possible shallow palaeochannels that anecdotally exist beneath the residential section of Garbutt (WSP 2018a) could act as a preferential pathway for PFAS impacted groundwater from the Base.


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8.3 NATURE AND EXTENT OF GROUNDWATER IMPACT Groundwater PFAS results are presented in Table 6, Appendix B and the extent of interpreted PFAS groundwater impact is shown on Figure 14 to Figure 16, Appendix A.

PFOS and PFHxS were detected at higher concentrations and more frequently then PFOA; therefore, the sum of PFOS and PFHxS is selected as the indicator parameter for impact, which aligns with the available human health water guidelines. It should be noted that the adopted guidelines are applicable to the point of receptor and have been conservatively applied to groundwater at the Base as a means of clearly identifying the important sources and the migration of PFAS in groundwater both beneath the Base and off-Base.

PFAS was detected in the majority of groundwater wells at the Base, with plumes interpreted to extend to the east and north-east from the south-eastern section of the Base, west and north-west from 5 AVN and north from the northern end of the runway. The highest PFAS concentrations were generally reported from monitoring wells installed at the known source areas or immediately downgradient of the source areas.

PFAS was detected in off-Base monitoring wells in the Town Common to the north-west, Bohle and Mount St John to the west, Pallarenda, Cleveland Bay and Rowes Bay to the north, Belgian Gardens to the north-east and Garbutt to the north-east and east of the Base. The highest PFAS concentrations were not always in the wells closest to the Base, with concentrations above the adopted ILs at a considerable distance from the Base in Bohle and Belgian Gardens.

A discussion on the temporal variation of the PFAS concentrations in groundwater (i.e. how the results compare to those reported in the DSI (2018a)) is provided in each of the following sections and considered holistically in Section 8.3.4, including a tabulated comparison of results between the monitoring programs.

8.3.1 SOURCE AREA IMPACTS

A summary of the source area on-Base groundwater impacts is provided in Table 8.2.

Table 8.2 Summary of on-Base groundwater screening results

BASE SOURCE AREA SCREENING LEVEL EXCEEDANCE?

NO. OF SAMPLES IN EXCEEDANCE OF ECOLOGICAL ILS

(TOTAL SAMPLE NO., IN BRACKETS)

NO. OF SAMPLES IN EXCEEDANCE OF HBGVS (TOTAL SAMPLE NO., IN

BRACKETS)

Fire training ground NQ0105 Yes 1 (2) 2 (2)

Fire training ground NQ0106 and OLAs

Yes 3 (6) 5 (6)

Pad Brahman Yes 3 (5) 3 (5)

Runway 13/31 Yes 4 (6) 6 (6)

Mount St John Yes 2 (4) 4 (4)

Fuel Farm 2 NQ0099 Yes 4 (4) 4 (4)

Fire station NQ0055 & fire training ground NQ0107

Yes 11 (11) 11 (11)

5 AVN Yes 9 (9) 9 (9)

38 SQN & domestic area Yes 7 (7) 7 (7)

Fire training ground NQ0054 & Fuel Farm 1 NQ0052

Yes 9 (9) 9 (9)

Ingham Road sports field Yes 0 (4) 4 (4)


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FORMER FIRE TRAINING GROUND NQ0105

Groundwater sampled from both monitoring wells in the area of fire training ground NQ0105 (MW241 and MW242) returned concentrations of PFOS + PFHxS in excess of the adopted human health screening criteria for drinking water and recreational use (2.30 µg/L and 0.43 µg/L respectively). These results have increased in MW241 and decreased in MW242 as compared to the ‘dry season’ results reported in the DSI (WSP 2018a). PFOS concentrations were above the adopted ecological criteria in MW242 only (0.22 µg/L), which is a decrease in concentration from the DSI (WSP 2018a) where PFOS returned a concentration of 1.06 µg/L.

Groundwater elevations in this area show a very slight gradient to the north-east, which has reversed since the dry season. PFAS impacted groundwater from fire training ground NQ0105 is interpreted to flow in a north-easterly direction towards the wetlands to the north of the Base.

FORMER FIRE TRAINING GROUND NQ0106 AND OLA

Groundwater sampled from one monitoring well in the area of fire training ground NQ0106 (MW243) returned a concentration of 1,380 µg/L for PFOS + PFHxS which is 1,322.5 µg/L higher than concentrations reported during the DSI (WSP 2018a). MW136 and MW265 are located to the north and north-east of the location of known fire training in area NQ0106. These two wells returned PFOS + PFHxS concentrations >1 µg/L and a significant increase was seen in PFAS concentrations in MW265 from the concentrations recorded in December 2017 (WSP 2018a).

Groundwater is interpreted to flow in a north-westerly to northerly direction from NQ016. Groundwater transport of PFAS from this area may be responsible for the PFOS + PFHxS detected in MW004 (0.14 µg/L) and MW122 (0.10 µg/L); however, local recharge of impacted surface water may also contribute to the PFAS concentrations in these wells. PFAS impact in MW004 and MW122 indicate that PFAS impacted groundwater is likely flowing off-Base to the north-west and north in this location.

PAD BRAHMAN AND NORTHWESTERN SITE BOUNDARY

Groundwater sampled from both monitoring wells at Pad Brahman (MW121 and MW244) returned concentrations of PFOS + PFHxS above the adopted human health drinking water and recreational use criteria (2.71 µg/L and 42.1 µg/L respectively), which were slightly higher than the concentrations reported during the DSI (WSP 2018a).

Groundwater elevations indicate that groundwater flow is towards the north at this location. PFOS + PFHxS concentrations at the Base boundary in MW002 (6.67 µg/L) and MW135 (8.76 µg/L) indicate that PFAS impacted groundwater is likely flowing off-Base into the Town Common to the north at this location. The PFAS impact in MW002 and MW135 is considered likely to be sourced from a combination of flow of PFAS impacted groundwater from Pad Brahman and impacted surface water flow and recharge of the aquifer in the vicinity of these wells.

RUNWAY 13/31 AND WESTERN SITE BOUNDARY

Groundwater sampled from both of the monitoring wells installed on the edge of Runway 13/31 (MW245 and MW246) returned concentrations of PFOS + PFHxS above the adopted human health drinking water and recreational use criteria (319 µg/L and 252 µg/L respectively) and PFOS above the adopted ecological guideline (60.2 µg/L and 198 µg/L respectively). These wells reported order-of-magnitude increases in PFAS concentrations compared with the ‘dry season’ DSI results (WSP 2018a).

The groundwater in this location is interpreted to flow to the north-west and west in the direction of Lake Lydeamore, and continues off-Base. Groundwater sampled from all of the five monitoring wells to the west of Lake Lydeamore (MW056, MW057, MW102, MW104 and MW112) returned concentrations of PFOS + PFHxS above the nominated human health criteria. PFAS concentrations increased in all of these wells in the post-wet season sampling event, with an order of magnitude increase reported in MW112.

PFOS + PFHxS was detected in groundwater from all three monitoring wells installed within the Base, but to the west of Louisa Creek (MW234, MW235 and MW255) at concentrations of 0.15 µg/L, 0.251 µg/L and 0.20 µg/L, respectively. Relatively small concentration increases were recorded in MW234 and MW235, and a small decrease in concentrations was recorded in MW255. Groundwater elevations suggest these wells are located across hydraulic gradient from the Base. The PFAS detected in these wells may be representative of off-Base sources, such as the Mount St John WTP;


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however, it is possible that there is a contribution from Base surface water runoff into Louisa and Peewee Creeks with subsequent groundwater recharge in the vicinity of these wells, particularly MW255 and MW234.

MW230, located on the south-western corner of the Base to the west of Louisa Creek returned a PFOS + PFHxS concentration of 1.34 µg/L, showing a significant increase in PFAS concentrations in the post-wet season sampling event. The up-gradient location of this well suggests that the PFAS detected in the groundwater is related to the up-gradient surface water impact detected in Louisa Creek (Section 8.4.5).

FUEL FARM 2 NQ0099

Groundwater sampled from all four monitoring wells at Fuel Farm 2 NQ0099 (MW005, MW046, MW081 and MW090) returned concentrations of PFOS + PFHxS above the adopted human health criteria for drinking water and recreational use, including MW081, which contained the highest concentrations of PFOS, PFHxS and PFOA at the Base (1,800 µg/L, 3,320 µg/L and 146 µg/L respectively). In contrast to the majority of results from the post-wet season sampling event, the PFAS concentrations decreased in all wells in this area compared with the DSI (August 2017) monitoring. The mechanism of this decrease in unclear.

Local groundwater elevations indicate that groundwater flow is towards the north in this location. During the DSI (WSP 2018a) significant PFAS concentrations were detected in the soil bores at this location, suggesting that the groundwater impact is from a local PFAS source rather than groundwater transport from a distant source. It is considered likely that the impact in this area is a result of firefighting systems testing and water truck purging, rather than fire training activities.

FIRE STATION NQ0055 AND FORMER FIRE TRAINING AREA NQ0107

Groundwater sampled from all monitoring wells in the area of the fire station NQ0055, fire training ground NQ0107 and surrounds returned concentrations of PFOS + PFHxS in exceedance of the adopted human health criteria for drinking water and recreational use, and the adopted ecological guidelines. The concentrations of PFOS + PFHxS were amongst the most elevated at the Base, ranging from 15.6 µg/L to 3,540 µg/L.

There was no discernible trend in PFAS concentration changes from the dry season to the wet season in this area, with six wells showing increases in PFAS concentrations and five wells showing decreases in PFAS concentrations. Local groundwater elevations indicate that groundwater flow from this area is north-west, towards the wetlands north-west of the OLAs.

5 AVN

Groundwater from all nine monitoring wells sampled at 5 AVN and surrounds returned concentrations of PFOS + PFHxS in exceedance of the adopted human health drinking water and recreational use criteria (0.477 µg/L – 2,240 µg/L) and concentrations of PFOS above the adopted ecological guideline. During the DSI (WSP 2018a), PFAS was not detected in MW142. Ultra-trace PFAS analysis was selected for MW142 during the post-wet season monitoring event and a PFOS+PFHxS concentration of 0.477 µg/L was reported.

Increases in PFAS concentrations were recorded for most of the wells in this area in the post-wet season sampling event, with small decreases in MW009 and MW249 the exception. Concentration increases were relatively small, with the exception of MW038, in which a two order of magnitude increase was recorded.

Local groundwater elevations indicate that groundwater flow from 5 AVN is to the west and north-west, towards Peewee Creek and Louisa Creek. The presence of PFAS in the monitoring wells along the western Base boundary in this area (MW009, MW043, MW125, MW247 and MW248) suggests that PFAS impacted groundwater is flowing off-Base from 5 AVN.

38 SQN AND DOMESTIC AREA

PFAS was detected in groundwater in all seven monitoring wells sampled at 38 SQN and the domestic area (MW006, MW036, MW049, MW061, MW063, MW224 and MW232) at concentrations above the adopted human health drinking water and recreational use criteria (0.39 µg/L – 43.6 µg/L) and concentrations of PFOS in all monitoring wells above the adopted ecological guideline (0.20 µg/L – 28.3 µg/L). Apart from the former Cadet training area (historic Cadet fire


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training and open day demonstrations on this field), no potential PFAS sources are known in the 38 SQN or domestic areas. Groundwater PFAS concentrations in the post-wet season sampling event increased slightly in five on the seven wells in this area, with slight decreases recorded in MS049 and MW232.

Groundwater elevations indicate that the domestic area is located on a piezometric high, from which groundwater may flow to the west, north and east. It is considered unlikely that the limited use of AFFF at the former Cadet training area would be responsible for the PFAS detected in groundwater beneath 38 SQN. Across gradient, groundwater flow from fire training ground NQ0054 may have contributed to the groundwater impact at 38 SQN; however, historical, local and unrecorded AFFF use is considered more likely to be the source.

Groundwater flow from 38 SQN is interpreted to be west north-westerly towards 5 AVN and Runway 07/25.

FORMER FIRE TRAINING AREA NQ0054 AND FUEL FARM 1 NQ0052

PFOS + PFHxS was detected in groundwater from all ten monitoring wells sampled at NQ0052 and NQ0054 and surrounds (MW013, MW026, MW033, MW034, MW051, MW116, MW118, MW120, MW126 and MW129) at concentrations in exceedance of the adopted human health criteria for drinking water and recreational use (1.39 µg/L – 424 µg/L) and PFOS concentrations above the adopted ecological guideline (0.79 µg/L – 342 µg/L). Groundwater PFAS concentration changes between the dry and wet season varied across this area, with small increases in six wells and small decreases in four wells.

Groundwater elevations indicate this area is located on a piezometric high, with groundwater flow directions potentially varying from west north-westerly to north north-easterly. Groundwater transport of PFAS may be responsible for the PFOS + PFHxS impact identified in MW222 and MW223 on the eastern Base boundary in this area (7.51 µg/L and 14.5 µg/L respectively). These concentrations are higher than those reported during the dry season GME (0.34 µg/L and 11.6 µg/L respectively) which suggests that historical surface water transport of PFAS and subsequent groundwater recharge may have also contributed to this PFAS groundwater impact.

Groundwater flow from these areas to the north, north-east and east are potentially transporting PFAS off-Base into Townsville Airport and Garbutt.

INGHAM ROAD SPORTS FIELD

Groundwater sampled from the four monitoring wells installed at the Ingham Road sports field (MW226 – MW229) returned concentrations of PFOS + PFHxS above the adopted human health criteria for drinking water (0.091 µg/L, 0.184 µg/L, 0.115 µg/L and 0.215 µg/L respectively). PFAS concentrations were higher in all wells than in the dry season (WSP 2018a). The use of AFFF at the fields during annual open day events is likely to have resulted in the infiltration of PFAS impact into groundwater beneath the fields. However, the relative contribution of PFAS to groundwater from this area is considered relatively minor compared with impacts at other areas of the Base.

Groundwater elevations indicate that groundwater flow from beneath the fields is to the north-west towards 5 AVN and Peewee Creek.

8.3.2 OFF-BASE IMPACTS

ECOLOGICAL AREA – THE TOWN COMMON

PFOS + PFHxS was detected in groundwater sampled from four of the eight monitoring wells installed at the Town Common, with one well (MW206) reporting concentrations of PFOS + PFHxS above the adopted human health drinking water and recreational use criteria and one well (MW208) reporting concentrations above the adopted drinking water criteria only. PFOS concentrations were not detected above the adopted 95% ecological criteria, but did exceed the 99% ecological criteria in all eight monitoring wells. The highest PFOS + PFHxS concentration was in MW206 (4.54 µg/L), which is located approximately 1,100 m north of the Base and is approximately 650 m further north of the Base than MW207, in which PFOS + PFHxS was not detected. This suggests that groundwater may not be the most important medium for the transport of PFAS in the Town Common. As MW206 is located closer to the perennial wetland in the centre of the Town Common than MW207, it is considered likely that surface water transport of PFAS off the Base with


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subsequent groundwater recharge into the underlying aquifer is responsible for the elevated PFOS + PFHxS concentrations in MW206.

PFAS concentrations in groundwater generally decreased in the wells at the Town Common in the post-wet season sampling event as compared to the DSI (WSP 2018a). Issues with detection limits obscure this trend slightly; however, it can be concluded that no significant increases were observed in groundwater PFAS concentrations in this area. Groundwater flow from the Town Common is considered to generally flow to the north-west towards Pallarenda.

PALLARENDA

Three groundwater monitoring wells (MW233, MW252, MW253) sampled at Pallarenda reported concentrations of PFOS + PFHxS above the laboratory LOR but below the adopted human health drinking water criteria and the ecological criteria (95% species protection). PFAS concentrations in Pallarenda groundwater have decreased slightly from the DSI (August 2017 monitoring). The mechanism of this decrease in unclear.

Groundwater elevations suggest that the aquifer beneath Pallarenda is likely connected to Three Mile Creek to the south-west of the residential areas. The low PFAS concentrations in these wells may be a result of groundwater recharge by impacted surface waters of the Common or impacted back-flow up Three Mile Creek during periods of high tide and/or flooding.

CLEVELAND BAY AND ROWES BAY

Groundwater from all four of the monitoring wells sampled at the former Rowes Bay landfill and five of the six monitoring wells installed along the Cleveland Bay and in Rowes Bay reported concentrations of PFOS + PFHxS above laboratory LOR, with five of the monitoring wells returning concentrations at or above the adopted human health drinking water criteria (MWRB1, MWRB5, MW264, MW209, and MW211). MW209 was the only location to exceed the adopted 95% ecological criteria, reporting a concentration of 0.22 µg/L for PFOS.

PFAS concentrations decreased in the post-wet season sampling event in all four wells at the former Rowes Bay landfill by minor amounts compared with the DSI (August 2017) results. Conversely, PFAS concentrations along the Cleveland Bay waterfront and in Rowes Bay increased slightly or were unchanged.

During the DSI (WSP 2018a) PFHxS was the only species of PFAS detected in MW264 at a concentration just above the laboratory LOR. The absence of appreciable PFAS in this well suggested no significant PFAS impact resulted from historical fire training activities reportedly conducted in this area. However, April 2018 sampling reported a concentration of 0.948 µg/L for PFOS + PFHxS, and several other common PFAS species were detected. It is unknown whether the identified PFAS impact is sourced from the suspected former fire training ground in the vicinity or from off-Base groundwater migration / surface water migration and subsequent groundwater recharge.

Post-wet season groundwater elevations suggest that the aquifer hosted by the dunes running parallel to the shoreline may receive recharge from the wetlands to the north of the Base, which receive PFAS impacted surface water discharge from the Base. It is possible that the PFAS detected in the Rowes Bay monitoring wells may be derived from recharge of this surface water.

Further south at the suburb of Rowes Bay, groundwater elevations suggest that a piezometric high exists between the wetlands of the Mundy Creek tributaries and the shoreline. Wet season recharge of this aquifer from the Mundy Creek wetlands may occur, which may explain low PFAS concentrations in MW211, MW212 and MW213.

BELGIAN GARDENS

Of the three monitoring wells sampled along the eastern side of Mundy Creek in Belgian Gardens (MW214 – MW216), groundwater in two (MW214 and MW216) returned PFOS + PFHxS concentrations above the nominated human health drinking water criteria. MW216 returned a PFOS concentration of 0.19 µg/L, which is above the adopted ecological guideline. Of the three wells sampled further to the east on the lower slopes of Castle Hill (MW256, MW261 and MW269), MW256 returned PFOS + PFHxS concentrations just above the nominated human health drinking water criteria. PFAS concentrations in all wells in this area increased slightly from the DSI (August 2017 sampling).


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Groundwater elevations indicate a general groundwater flow to the north-east in the vicinity of Mundy Creek; however, local contours suggest groundwater also flows south-eastwards from Rowes Bay towards MW215 and north-westwards from Castle Hill towards Mundy Creek.

The relatively elevated PFOS + PFHxS concentration in MW216 (0.57 µg/L) is anomalous when compared with the results of monitoring wells nearer to known PFAS sources. Discounting an unknown local PFAS source, impacted surface water from Mundy Creek would appear to be the most logical source for the PFAS in this well. The slightly elevated concentration in MW256, which is up-gradient from the rest of the IA, suggests an unidentified background source of PFAS in this vicinity.

GARBUTT

Groundwater sampled from the monitoring wells installed in the suburb of Garbutt, to the immediate east of the Base, generally followed a pattern of higher PFOS + PFHxS concentrations at or near the Base boundary (6.84 µg/L in MW221, 7.51 µg/L in MW222 and 14.5 µg/L in MW223) with downgradient monitoring wells reporting lower concentrations (0.0021 µg/L in MW217, 0.13 µg/L in MW218, 0.0140 µg/L in MW219 and 0.0776 µg/L in MW220). All of these concentrations are higher than those reported in the August 2017 monitoring event (WSP 2018a). Ultra-trace PFAS analysis was conducted during the post-wet season sampling event and as a result, some concentrations that were reported below the laboratory LOR during the DSI now have reportable concentrations due to the sensitivity of the analysis undertaken. MW221, MW222, MW223, MW225, MW258, MW263 and MW267 all exceeded the adopted ecological criteria with PFOS concentrations reported of 0.23 µg/L – 2.26 µg/L.

The elevated PFAS concentrations in MW263 compared with the surrounding groundwater results support the concept of a palaeochannel forming a preferential pathway for PFAS impacted groundwater migration off-Base in this area.

Groundwater elevations indicate a north-easterly to easterly groundwater flow direction from the Base towards the Mundy Creek catchment (Figure 11). The groundwater contours suggest MW225 to be across hydraulic gradient from the south-eastern corner of the Base. The relatively elevated PFOS + PFHxS concentration reported from MW225 (0.43 µg/L) is considered unlikely to be a result of a cross-gradient groundwater transport approximately 300 m from Base.

Delineation to below detection levels was not attained as across gradient well MW266 returning PFOS + PFHxS concentrations of 0.0074 µg/L and up-gradient wells MW257 – MW260 recorded PFOS + PFHxS concentrations of 0.0914 µg/L to 0.49 µg/L. The source of PFAS impact in these wells is uncertain, but may be representative of background groundwater concentrations in this section of Garbutt. No off-Base potential sources of AFFF or PFAS use are known in the area.

Up-gradient well MW236 returned a concentration of PFOS + PFHxS of 0.0086 µg/L, demonstrating the common occurrence of low-concentration PFAS in groundwater in Garbutt.

BOHLE

Concentrations of PFOS + PFHxS above the adopted human health criteria concentration were detected in groundwater from MW237 (0.0801 µg/L), MW238 (0.0890 µg/L), MW239 (0.422 µg/L) and MW240 (0.358 µg/L). These concentrations are higher than those reported during the DSI (WSP 2018a), with order of magnitude increases reported in MW239 and MW240. Remobilisation of PFAS in pore spaces or adsorbed to soil in the capillary zone through groundwater level rise may be responsible for this concentration increase.

Groundwater elevations of these four wells indicate local groundwater flow to the north-west, towards the Bohle River. One or more of the identified potential off-Base sources of PFAS in this area are considered to have contributed to groundwater PFAS impact in the area, and are potential contributors to the surface water PFAS impact identified in the upper and middle reaches of the Bohle River. However, the absolute values of PFOS + PFHxS and other PFAS compounds in these wells suggests that the overall contribution of PFAS to the Bohle River catchment from these off-Base sources is minor relative to the flux from Base.


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MOUNT ST JOHN

Two monitoring wells in the industrial section of Mount St John, to the west of the Mount St John WTP (MW254 and MW262) were sampled and analysed for the ultra-trace PFAS suite due to concentrations being below the laboratory LOR during the DSI (WSP 2018a). Both wells reported concentrations of PFOS + PFHxS of 0.0062 µg/L. There were no exceedances of any adopted human health drinking or recreational water or 95% species protection ecological criteria; however, both samples exceeded the 99% species protection ecological criteria. The low concentration of PFAS in these two wells suggest that low concentrations of PFAS may be entering the Town Common through north-easterly groundwater movement.

PRIVATE WATER BORES

Confidentiality prevents the discussion of results from individual private water bores. The results gained from samples collected from private water bores agree with the results from the other monitoring wells sampled and analysed as part of the investigation.

8.3.3 INTERPRETED PLUME OF GROUNDWATER IMPACTS

Groundwater sampled from all monitoring wells on the Base returned elevated PFAS concentrations, indicating widespread PFAS in groundwater impact beneath the Base. During the DSI (WSP 2018a) the absence of PFAS in isolated monitoring wells (MW104, MW140 and MW142) suggested that there was not one continuous PFAS ‘plume’ beneath the Base, but a series of PFAS ‘plumes’ and multiple pathways related to specific source areas and possibly surface water bodies. To increase the data set from the DSI, groundwater sampling locations that had previously returned concentrations below the LOR were selected for ultra-trace PFAS analysis for the post-wet season monitoring event. Ultra-trace analysis has shown that PFAS appears to be ubiquitous in groundwater beneath the Base; however, elevated concentrations are associated with individual source areas rather than being at a uniform concentration across the IA .

The detection of PFAS in all off-Base monitoring wells (with the exception of monitoring wells analysed at a higher detection limit - MW202, MW204, MW205, MW207 and MW212) to the north-west, north, north-east, south-east and east of the Base suggests that groundwater ‘plumes’ have transported PFAS off-Base in these directions. However, irregularities in the results, such as the anomalously high results in MW206 and MW216, suggest that the groundwater impacts are not continuous plumes’ in the traditional hydrogeological sense i.e. a relatively homogeneous dissolved mass of chemical with steadily declining concentration away from the primary source. Elevated concentrations of PFAS in groundwater at a distance from the Base are considered more likely to be a result of surface water PFAS transport with subsequent infiltration of PFAS impacted water into the underlying aquifer.

The discharge monitoring undertaken during March 2018 supports this theory, with large volumes of surface water with relatively high concentrations of PFAS observed to be draining off the Base into the surface water bodies of the Town Common and the Three Mile Creek and Mundy Creek catchments.

The groundwater impact to the south (up-gradient) and south-east (across-gradient) of the Base is considered likely to be the result of an unidentified off-Base source.

8.3.4 COMPARISON OF POST-WET SEASON GROUNDWATER RESULTS WITH PREVIOUS INVESTIGATIONS

A detailed historical review of PFAS concentrations in groundwater at the Base prior to 2017 is included in the DSI (WSP 2018a). The review revealed significant variability (over three orders of magnitude) between monitoring events in some monitoring wells; however, since 2016, the results rarely varied by more than an order of magnitude. Significant variability was observed in the results of multiple samples collected from some individual wells, despite being collected using the same sampling methodology and approximately six weeks apart. Natural variability in PFAS distribution was considered to be the most likely cause for the variability in repeated groundwater test results.

Comparisons of the PFAS concentrations in groundwater between the DSI (August 2017) and post-wet season (April 2018) monitoring events was undertaken to investigate the potential impact of the wet season and the subsequently


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elevated groundwater levels (generally) which remained for some time following the significant rainfall event in March 2018.

Table 8.3 below presents the changes in PFOS + PFHxS concentrations in groundwater sampled on-Base in the dry and wet periods.

Table 8.3 On-Base changes in concentrations of PFOS + PFHxS between dry and wet period sampling

LOCATION WELL ID AUGUST 2017 PFOS + PFHXS

CONCENTRATION (µg/L)

APRIL 2018 PFOS + PFHXS


CHANGES (µg/L)

(+ INCREASE / - DECREASE)

Former Fire Training Area

NQ0105

MW241 0.08 2.30 +2.22

MW242 1.74 0.43 -1.31

Former Fire Training Area

NQ0106

MW004 0.06 0.14 +0.08

MW122 0.13 0.10 -0.03

MW136 1.77 1.73 -0.04

MW243 57.5 1,380 +1,323

MW265 – 2.46 +2.46

Pad Brahman and north-western Base boundary

MW002 5.55 6.67 +1.12

MW121 2.25 2.71 +0.46

MW135 11.2 8.76 -2.44

MW244 39.6 42.1 +2.5

Runway 13/31 and western Base

boundary

MW056 2.13 3.46 +1.33

MW057 11.9 24.3 +12.4

MW102 2.31 2.96 +0.65

MW104 <0.05 0.15 +0.15 (*)

MW112 4.22 38.3 +34.08

MW245 24.7 319 +294.3

MW246 32.4 252 +219.6

Mount St John (on-Defence land)

MW230 – 1.34 +1.34

MW234 0.13 0.15 +0.02

MW235 0.06 0.251 +0.191

MW255 – 0.20 +0.20

Fuel Farm 2 NQ0099

MW005 622 405 -217

MW046 346 238 -108

MW081 6,360 5,120 -1,240

MW090 7.06 4.03 -3.03


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CHANGES (µg/L)


Fire station NQ0055, fire

training ground NQ0107

MW015 530 3,540 +3,010

MW016 928 1,400 +472

MW021 708 513 -195

MW054 50.5 126 +75.5

MW055 290 51.7 -238.3

MW109 1,270 970 -300

MW110 1,220 2,000 +780

MW138 291 156 -135

MW139 862 2,220 +1,358

MW140 <0.05 0.139 +0.139 (*)

MW250 30.2 26.0 -4.2

MW251 1.18 17.3 +16.12

5 AVN MW009 20.6 15.4 -5.2

MW038 6.33 1,050 +1,044

MW043 273 316 +43

MW114 24.6 71.5 +46.9

MW125 66.2 1,300 +1,234

MW142 <0.05 0.477 +0.477 (*)

MW247 102 129 +27

MW248 1,170 2,240 +1,070

MW249 155 4.40 -150.6

38 SQN and Domestic Area

MW006 0.25 0.39 +0.14

MW036 1.82 5.53 +3.71

MW049 3.86 2.30 -1.56

MW061 21.6 29.4 +7.8

MW063 30.4 43.6 +13.2

MW224 0.79 2.03 +1.24

MW232 22.5 13.8 -8.7

MW013 172 340 +168

MW026 35.6 15.6 -20

MW033 38.6 38.7 +0.1

MW034 17.0 17.2 +0.2

MW051 1.79 1.39 -0.4


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CHANGES (µg/L)


Former fire training ground

NQ0054 and Fuel Farm 1 NQ0052

MW116 316 83.2 -232.8

MW118 4.15 1.60 -2.55

MW120 37.9 52.7 +14.8

MW126 452 424 -28

MW129 41.8 52.0 +10.2

Ingham Road playing fields

MW226 0.06 0.0911 +0.0311

MW227 0.08 0.184 +0.104

MW228 <0.05 0.115 +0.115 (*)

MW229 <0.05 0.215 +0.215 (*)

Notes:

– Samples not collected. (*) Samples were below the laboratory LOR

Table 8.4 below presents the changes in PFOS + PFHxS concentrations in groundwater sampled off-Base in the dry and wet periods.

Table 8.4 Off-Base changes in concentrations of PFOS + PFHxS between dry and wet season sampling





CHANGES (µg/L)

(INCREASE / DECREASE)

Town Common MW201 <0.01 0.0285 +0.0285 (*)

MW202 0.02 <0.10 -0.02(*)

MW203 <0.01 0.0041 +0.0041(*)

MW204 0.03 <0.01 -0.03

MW205 0.74 <0.05 -0.74(*)

MW206 15.9 4.54 -11.36

MW207 0.08 <0.05 -0.08(*)

MW208 0.14 0.15 +0.01

Cleveland Bay MW209 0.19 0.44 +0.25

MW210 0.02 0.07 +0.05

MW211 0.07 0.15 +0.08

Rowes Bay MW212 0.01 <0.01 -0.01 (*)

MW213 <0.01 0.0107 +0.0107 (*)

MW264 – 0.948 +0.948


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CHANGES (µg/L)


Belgian Gardens MW214 <0.05 0.102 +0.102 (*)

MW215 0.02 0.0477 +0.0277

MW256 – 0.095 +0.095

MW261 – 0.0391 +0.0391

MW269 – 0.0407 +0.0407

Garbutt MW216 0.35 0.57 +0.22

MW217 <0.05 0.0021 +0.0021 (*)

MW218 0.08 0.13 +0.05

MW219 <0.01 0.0140 +0.0140 (*)

MW220 0.03 0.0776 +0.0476

MW221 5.70 6.84 +1.14

MW222 0.34 7.51 +7.17

MW223 11.6 14.5 +2.9

MW225 0.32 0.43 +0.11

MW236 <0.01 0.0086 +0.0086 (*)

MW257 – 0.0914 +0.0914

MW258 – 0.49 +0.49

MW259 – 0.25 +0.25

MW260 – 0.24 +0.24

MW263 – 1.09 +1.09

MW266 – 0.0074 +0.0074

MW267 – 0.90 +0.90

MW268 – 0.0011 +0.0011

MW270 – 0.0032 +0.0032

Bushland Beach MW231 0.06 0.0313 -0.0287

Bohle MW237 <0.01 0.0801 +0.0801 (*)

MW238 <0.05 0.0890 +0.089 (*)

MW239 0.06 0.422 +0.362

MW240 0.09 0.358 +0.268

Pallarenda MW233 – 0.01 -0.01

MW252 – 0.0114 +0.0114

MW253 – 0.0055 +0.0055

Mount St John (off Defence land)

MW254 – 0.0062 +0.0062

MW262 – 0.0062 +0.0062


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CHANGES (µg/L)


Off-Base commercial

monitoring wells

MW401 0.10 – -0.10

MW402 0.33 – -0.33

MW403 0.09 – -0.09

MW405 0.82 1.98 +1.16

MW406 1.49 – -1.49

MW414 1.44 1.60 +0.16

MW415 3.09 4.34 +1.25

MW422 0.29 0.05 -0.24

MW437 0.21 0.31 +0.10

MW439 0.33 0.66 +0.33

MW455 5.08 0.65 -4.43

MW456 0.93 0.99 +0.06

MW457 2.42 8.25 +5.83

MW459 5.24 6.66 +1.42

MW460 0.06 4.06 +4.00

MW463 0.05 0.823 +0.773

MW465 0.80 0.02 -0.78

MW466 0.98 <0.01 -0.98 (*)

Former Rowes Bay Landfill

MWRB1 0.12 0.10 -0.02

MWRB2 0.08 0.0576 -0.0224

MWRB3 0.05 0.0311 -0.0189

MWRB5 0.47 0.14 -0.33

Notes:

– Samples not collected. (*) Samples were below the laboratory LOR

PFAS concentrations increased in the post-wet season sampling in more wells (57%) than wells in which the PFAS concentration decreased (29%). Concentrations were approximately the same or below detection limit in 14% of the wells. However, the majority of the differences in concentration were less than an order of magnitude (62%). Significant differences (greater than an order of magnitude) were observed in 42% of wells with increased concentrations, but only 27% of wells with decreased concentrations. Three monitoring wells (MW038, MW125 and MW243) showed two order of magnitude increases in concentration in the post-wet season sampling event, but no wells showed a two order of magnitude decrease.

Fourteen wells (10 on-Base) that previously reported PFAS concentrations below a particular HBGV (drinking water or recreational water guidelines, HEPA 2018) in the DSI (August 2017) now reported a result above that HBGV (April 2018). Conversely, decreases in concentration resulted in seven wells (one on-Base) that previously had PFAS concentrations above a particular HBGV, now returning concentrations below that HBGV.


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Significant variability in repeated groundwater test results during 2017 (WSP 2018a) was generally only observed in highly impacted wells and on no occasion did results alter the screening result against the nominated guideline. Comparison of the post-wet season and DSI results; however, indicates that the screening results for a particular well may vary significantly between wet and dry periods. This reinforces the need for wet and dry season monitoring in the IA. No definitive trends were discernible in the data set. Additional monitoring events would be required to confirm whether observed increases/decreases in specific wells between wet and dry seasons are repeatable and a result of mechanisms such as increased mobilisation from source zones, increased transportation along groundwater flow paths and increased recharge from surface water, or are due to natural variability within the groundwater column.

8.3.5 POTENTIAL MECHANISMS OF PFAS BEHAVIOUR EXPLAINING WET SEASON GROUNDWATER RESULTS

The fact that PFAS compounds do not readily breakdown in surface water or groundwater means that the main mechanisms for the attenuation of PFAS in these media are dilution and sorption. A predisposition for a compound to sorb to soil particles or organic matter may lead to retardation of the compounds movement in groundwater, or the removal of the compound from surface water. A potential mechanism for PFAS re-mobilisation in groundwater is desorption from the soil in the ‘smear’ zone i.e. the zone where the water table fluctuates up and down. As the water table drops dissolved PFAS may be trapped in pore spaces within the soil/rock or the PFAS may adsorb to clays and organic materials within the soils. When the groundwater table rises again, the trapped and / or adsorbed PFAS may be liberated into the groundwater. This may explain why concentrations of PFAS are higher during the post-wet season sampling event in the majority of the wells, particularly those with elevated PFAS concentrations near identified PFAS sources on-Base.

A comparison of changes in SWL and concentrations in groundwater wells between the dry period and wet season is shown on Figure 8.1. All wells that show significant increase in PFOS+PFHxS concentration had an increase in SWL; however the positive correlation is not strong.


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Figure 8.1 Relationship of changes groundwater PFOS+PFHxS concentrations and groundwater levels between August 2017 and April 2018

As part of the DSI (WSP 2018a), an attempt was made to calculate a partition coefficient (Kd) using soil and groundwater concentrations collected from the same interval of newly installed monitoring wells. However, a limited data set (seven data pairs) was available and the highly variable results (Kd of 0.3 to 42) implied that a meaningful result could not be calculated. Figure 8.2 shows the comparative concentrations of PFOS + PFHxS in the seven monitoring wells for which data was available. No monitoring wells were installed during the Seasonal Monitoring; therefore, no additional data was available to increase the data set.

A positive correlation between PFOS + PFHxS in soil and groundwater is shown on Figure 8.2 for the limited data available. The results indicate that PFAS is likely being adsorbed by the aquifer matrix in impacted groundwater, leading to retardation of PFAS transport in groundwater. However, the scale and implications for PFAS transport in groundwater are currently unquantifiable.

-1500

-1000

-500

0

500

1000

1500

2000

2500

3000

3500

-1 -0.5 0 0.5 1 1.5 2 2.5

Diff

eren

ce in

PFO

S+PF

Hx

conc

entra

tion

betw

een

Aug

st 2

017

& A

pril

2018

(µg/

L)

Statigroundwater level between Augut 2017 & April 2018 (m)

Groundwater


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Figure 8.2 PFOS + PFHxS in soil and groundwater

8.4 NATURE AND EXTENT OF SURFACE WATER AND SEDIMENT IMPACT

Sediment and surface water PFAS results are presented in Tables 7 and 8, respectively, Appendix B and the extent of interpreted PFAS surface water and sediment impact is shown on Figures 17 to Figure 22, Appendix A. PFOS and PFHxS were detected at higher concentrations and more frequently than PFOA; therefore, the sum of PFOS and PFHxS is selected as the indicator parameter for impact, which aligns with the available human health water guidelines.

8.4.1 SURFACE WATER HYDROLOGY

The topography of the IA is generally flat, with surface water gradients being shallow and creating a low-energy environment. This leads to low flow rates during dry periods, sediment deposition and heavily vegetated water bodies. During the significant rainfall event in March 2018, the surface drains contained significant flow that was sufficiently swift to allow disturbance and transport of the previously deposited sediments. Flows in the drains stopped within two to three weeks of this rainfall event, with no flow or minor flow observed in all watercourses during the subsequent post-wet season (April 2018) monitoring event. The lower reaches of the watercourses in the IA are tidally influenced, as evidenced by the elevated salinity of the surface water at these points.

Large ponded water bodies occur in the wetlands on the western side of the Base and in the Town Common. Based on their size, these water bodies are likely to be permanent except for in the severest drought. Smaller ponds are present to the north of the Base in the upper reaches of Three Mile Creek and the tributaries of Mundy Creek. Large areas of the Base became inundated during the significant rainfall event in March 2018, with active pumping into Lake Lydeamore and the wetlands to the north of the Base observed. Significant volumes of water flowed off-Base into the surrounding wetlands to the north-west, north and north-east during this event.

0

20

40

60

80

100

120

140

160

180

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14

Gro

undw

ater

PFO

S +

PFH

xS (µ

g/L)

Soil PFOS + PFHxS (mg/kg)


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8.4.2 SOURCE AREAS AND SURFACE WATER

A summary of the surface water drainage networks at each of the potential PFAS source areas is presented in Table 8.5.

Table 8.5 PFAS source area surface water drainage

PFAS SOURCE AREA NATURE OF DRAINAGE NETWORK RECEIVING WATER BODY

Former fire training area NQ0105

Grassed swales to concrete-floored open drain.

Northern and western sections to Three Mile Creek; eastern section to Mundy Creek.

Former fire training area NQ0106

Grassed swales to concrete-floored open drain.

Northern section to internally draining pond at OLAs; southern section to on-Base wetlands, ultimately to the Town Common.

Pad Brahman No formed drains, overland flow. On-Base wetlands, ultimately to the Town Common/Louisa Creek.

Runway 13/31 No formed drains, overland flow off runway.

Lake Lydeamore, ultimately to Louisa Creek.

Fuel Farm 2 Grassed swales and overland flow. On-Base wetlands, ultimately to the Town Common.

Fire station NQ0055 & former fire training area NQ0107

Grassed swales and overland flow. On-Base wetlands, ultimately to the Town Common.

5 AVN Hangar areas have stormwater drains discharging to a separation tank which discharges to a concrete floored drain and off-Base via a triple interceptor; the wash bay area drains to a grassed swale to concrete-floored drain.

Peewee Creek and Louisa Creek.

Domestic Area Overland flow from grassed field to stormwater drains to concrete drains.

Mundy Creek

Former fire training area NQ0054 & Fuel Farm 1 NQ0052

Grassed swales to concrete-floored drains and concrete drains.

Mundy Creek

Ingham Road Sports Fields Grassed swales to unlined drains. Peewee Creek

Table 8.5 indicates that most of the source areas are drained by unlined or partially-lined drains, resulting in surface water readily infiltrating into the subsurface. However, during significant rainfall events, these drains flow relatively swiftly to the on-Base wetlands and/or off-Base for a short period (one or two weeks in March 2018).


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8.4.3 PFAS MIGRATION TO SURFACE WATER

The primary mechanisms for PFAS migration into surface waters at the Base are considered to be:

— surface water (rainfall, irrigation water or wash-water) dissolving PFAS in soils or pavements on the ground surface and discharging directly into the drainage network

— historical AFFF use directly discharging into the surface drainage system, or carried by wind into surface drains; and

— vadose zone water dissolving PFAS in soil and discharging into deeper surface water drains via their embankments during periods of heavy rainfall.

A graph of April 2018 surface water PFOS + PFHxS concentrations against sediment PFOS + PFHxS concentrations is shown in Figure 8.3. The graph shows a positive correlation between sediment and surface water concentrations, which shows a similar trend to the DSI (August 2017) results, suggesting that the storage of PFAS in sediments and subsequent desorption of PFAS into surface waters from the sediments may be an important mechanism for the transport of PFAS in surface waters off-Base. However, the reverse mechanism may also occur, whereby PFAS impacted surface water flows off-Base to a still or slow-moving water body. If the PFAS comes into contact with clays or organic matter in the water body, the PFAS may sorb to the clay or organic material, forming a PFAS sink, which may later desorb back into the surface water or into vadose zone water, potentially reaching groundwater at a distance from the original PFAS source.

Figure 8.3 April 2018 – PFOS + PFHxS in surface water and sediment

0.0001

0.001

0.01

0.1

1

10

100

0.0001 0.001 0.01 0.1 1 10 100 1000

Surf

ace

Wat

er P

FOS

+ PF

HxS

(µg/

L)

Sediment PFOS + PFHxS (mg/kg)

Surface water vs Sediment PFOS + PFHxS


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8.4.4 SIGNIFICANT RAINFALL EVENT DISCHARGE

Surface water sampling was conducted from four locations on-Base, where accessible, immediately following the significant rainfall event that occurred in March 2018.

Surface water was discharging from the Base into the wetlands to the north of the Base following the rainfall event. Due to accessibility issues, a surface water sample was not collected from SW102 on the 1 March 2018. Samples were collected from this location over the period 2 March – 5 March 2018; however, with PFOS + PFHxS concentrations reporting 0.529 µg/L, 0.437 µg/L, 0.787 µg/L and 0.763 µg/L, respectively, showing a slight increase with time.

These results indicate that during periods of significant rainfall, PFAS impacted surface water is being discharged from the Base into the Three Mile Creek catchment at concentrations close to the recreational HBGV. The PFAS in this water is likely sourced from the former fire training grounds NQ0105 with some input from runway 01/19 and the OLAs.

Surface water was discharging from the Base into the wetlands to the west of the Base formed by the overflow of Louisa Creek and Peewee Creek following the significant rainfall event. Surface water samples were collected at SW123 from 1 March – 5 March 2018, with PFOS + PFHxS concentrations reporting 2.44 µg/L, 6.38 µg/L, 9.89 µg/L, 35.4 µg/L and 37.1 µg/L, respectively, showing a steady increase over the first three days followed by a significant increase on the fourth and fifth days of sampling.

These results indicate that during periods of significant rainfall, PFAS impacted surface water is being discharged from the Base into the Three Mile Creek catchment at concentrations one to two orders of magnitude greater than the recreational HBGV. The PFAS in this water is likely sourced from the hangars and wash points at 5 AVN. The jump in concentrations coincided with a decrease in flow on these dates. Comparison of the surface water and groundwater levels in April 2018 (Section 8.2.4) suggested that the groundwater daylighted in this channel. The significant increase in PFAS concentrations at this sampling location may represent groundwater contribution to the surface water following a rise in the groundwater table.

The surface water discharge locations on the north-western boundary of the Base (SW013 and SW016) were not able to be accessed. A new location (SW131) between the OLAs and Pad Brahman was selected to capture discharge concentrations from the OLAs NQ0106, Fire Station NQ0055, Fuel Farm 2 NQ0099 and the northern side of Runway 13/31. Surface water samples were collected at SW131 from 2 March – 5 March 2018, with PFOS + PFHxS concentrations reporting 5.52 µg/L, 4.54 µg/L, 6.88 µg/L and 5.09 µg/L, respectively, showing no appreciable change in concentration over the period of sampling.

These results indicate that during periods of significant rainfall, PFAS impacted surface water is being discharged from the Base into the on-Base wetlands and the off-Base Town Common wetlands at concentrations an order of magnitude greater than the recreational HBGV (HEPA 2018). Pump locations are shown on Figure 4b, Appendix A.

A new surface water location (SW132) was also selected at the discharge point of the Base into the Mundy Creek catchment to capture runoff from the former fire training ground NQ0054, Fuel Farm 1 NQ0052 and the domestic area. Surface water samples were collected at SW132 from 1 March – 5 March 2018, with PFOS + PFHxS concentrations reporting 41.7 µg/L, 42.1 µg/L, 40.5 µg/L, 46.4 µg/L and 39.7 µg/L, respectively, showing no appreciable change in concentration over the period of sampling.

Figure 8.4 shows a comparison of PFOS+PFHxS against EC in surface water samples during the March 2018 discharge sampling. A relationship of increased PFAS with increased EC appears to be observable; however, inspection of individual results shows that, with the exception of SW123, PFAS concentrations did not increase with increased EC. The increased concentrations and EC in SW123 may be a result of groundwater discharge.


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Figure 8.4 Discharge sampling PFOS+PFHxS and EC

These results indicate that during periods of significant rainfall, PFAS impacted surface water is being discharged from the Base into the Mundy Creek catchment at concentrations two and a half orders of magnitude greater than the recreational HBGV (HEPA 2018).

8.4.5 NATURE AND EXTENT OF SURFACE WATER AND SEDIMENT IMPACT

The following sections discuss the PFAS impact identified in on-Base and off-Base surface waters and associated sediments. Results are discussed by catchment, with on-Base source areas linked to off-Base catchments. Sediments have been discussed in association with surface waters as they are considered to be intimately linked in PFAS distribution mechanisms in the IA on the basis of both DSI and post wet-season results and published data.

THREE MILE CREEK

On-Base surface waters that ultimately discharge to Three Mile Creek were represented by samples SW103 and SW104, which returned PFOS + PFHxS concentrations of 1.39 µg/L and 1.24 µg/L, respectively. Sediments collected from the drain that collects surface runoff from former fire training area NQ0105 and between the OLAs and Runway 01/19 (SD103, SD104 and SD105) reported PFOS + PFHxS concentrations ranging from 29.1 µg/kg to 105 µg/kg.

The concentration of PFOS + PFHxS was slightly higher in SW103 during the post-wet season sampling event. No surface water was present at SW104 during the DSI. PFOS + PFHxS concentrations in sediments were slightly higher in SD103 during the post-wet season sampling event but slightly lower in SD104. No sample was collected from location SD105 during the DSI. PFAS concentrations in surface water were higher during the post-wet season sampling event than they were during the discharge sampling event (Section 8.4.4).

Surface water samples from wetlands to the immediate north of the Base (SW101, SW102 and SW107) reported PFOS + PFHxS concentrations in exceedance of the ecological screening levels (1.04 µg/L, 1.38 µg/L and 0.613 µg/L, respectively). Sediments from these locations reported PFOS + PFHxS concentrations of 6.9 µg/kg to 12.6 µg/kg, with the highest concentrations reported from the natural pool immediately downstream of the Base discharge point.

Post-wet season surface water concentrations of PFOS + PFHxS were higher than the DSI (WSP 2018a) results at SW102 and SW107. No surface water was present at SW101 during the DSI. Sediment PFOS + PFHxS concentrations decreased by half an order of magnitude from the DSI, excepting SD101, which doubled in PFOS + PFHxS concentration.

PFAS is being transported by surface waters from the Base into the Three Mile Creek catchment. It is unclear whether the sediments are transporting PFAS off-Base as well, or whether the PFAS is binding to the sediments from impacted surface waters. Surface water collected from the mouth of Three Mile Creek (SW210) returned a PFOS + PFHxS

0

500

1000

1500

2000

2500

0 10 20 30 40 50 60 70 80

EC (µ

S/cm

)

PFOS + PFHxS (µg/L)

Surface water PFOS+PFHxS vs EC - DIscharge sampling March 2018

SW102

SW123

SW131

SW132


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concentration of 0.0764 µg/L. No PFAS was detected at this location during the DSI (WSP 2018a). Sediments collected at this location returned a PFOS + PFHxS concentration of 1.5 µg/kg during the post-wet season sampling event, which was slightly lower than the DSI.

The wet season results from Three Mile Creek suggest that PFAS has potentially desorbed from sediments and shallow sub-surface soils and become mobile through the flow of surface water and has been discharged from the Base. The detection of PFAS at the mouth of Three Mile Creek suggests that with stronger freshwater flow in the estuary, PFAS is remaining dissolved in the surface water closer to the waters of Cleveland Bay.

THE TOWN COMMON WETLANDS

On-Base drainage lines that ultimately discharge to the Town Common wetlands include those that drain the potential PFAS source areas of the former fire training ground NQ0106, fire station NQ0055, former fire training area NQ0107, Pad Brahman, the northern side of Runway 13/31 and Fuel Farm 2 NQ099. Surface water samples collected from these source areas (SW039 and SW126) returned PFOS + PFHxS concentration of 455 µg/L and 5.69 µg/L, respectively. Sampling locations SW012 and SW013, on the Base’s northern boundary, returned PFOS + PFHxS concentrations of 6.59 µg/L and 9.50 µg/L, respectively. Sediments from the source areas reported PFOS + PFHxS concentrations ranging from 0.384 mg/kg to 93.6 mg/kg. Sediments on the northern boundary of the Base returned PFOS + PFHxS concentrations of 0.0147 mg/kg (SD012) and 0.109 mg/kg (SD013).

Post-wet season surface water PFOS + PFHxS concentrations were slightly lower than the DSI sample concentrations (WSP 2018a). Conversely, post-wet season sediment PFOS + PFHxS concentrations were up to an order of magnitude higher than the DSI results, with the exception of SD302, in which PFOS + PFHxS concentrations decreased by an order of magnitude.

Surface water samples were collected from the eastern margin of the main water body in the Town Common (SW110 and SW111). These two locations reported PFOS + PFHxS surface water concentrations of 6.32 µg/L and 4.17 µg/L, respectively. Sediment PFOS + PFHxS concentrations at these locations were 105 µg/kg and 21.2 µg/kg, respectively.

Post-wet season PFOS + PFHxS concentrations were slightly higher than DSI concentrations in sediments and surface water samples at SW110 / SD110. However, post-wet season PFOS + PFHxS concentrations in sediments and surface water samples at SW111 / SD111 were slightly lower than DSI results (WSP 2018a). The PFAS concentration changes are considered to be indicative of the natural variability of PFAS within the sample media.

These results indicate that surface water containing PFAS impact above the ecological screening levels has been transported at least 1.2 km into the Town Common from the Base. Whether the sediments have been physically transported to their current location containing the PFAS, or the organic-rich sediments have bound PFAS from the overlying surface water is unclear.

LOUISA AND PEEWEE CREEKS UPSTREAM

Five surface water and sediment samples in total were collected from Louisa Creek (SW014, SW127 and SW128) and Peewee Creek (SW017 and SW120) upstream of any potential PFAS influence from the Base. PFOS + PFHxS was detected in all surface water samples during the post-wet season sampling, at concentrations of 0.0543 µg/L to 0.0650 µg/L in Louisa Creek and 0.210 µg/L to 0.250 µg/L in Peewee Creek. PFOS + PFHxS was not detected in sediments collected from Peewee Creek, but in Louisa Creek one sediment sample (SD127) reported a PFOS + PFHxS concentration of 0.001 mg/kg, whilst the other two locations were below detection limits.

Post-wet season surface water concentrations of PFOS + PFHxS were lower by an order of magnitude in Louisa Creek and slightly lower in Peewee Creek than in the DSI. Sediment PFOS + PFHxS concentrations, when detected, were slightly lower in the post-wet season event than the DSI results. Dilution from low-PFAS concentration floodwaters upstream of the Base may have caused the decrease in PFAS concentrations in the post-wet season samples.

These results indicate a background source of PFAS exists in the upper catchments of Louisa and Peewee Creeks, with some surface water concentrations above drinking water guidelines (HEPA 2018). However, compared with the concentrations recorded in surface waters discharging from the Base, the background input of PFAS is considered to be minor.


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LOUISA CREEK DOWNSTREAM

Louisa Creek receives surface water runoff from the potential on-Base PFAS sources of the western side of Runway 13/31 (via Lake Lydeamore in periods of high flow), the western section of 5 AVN and, via Peewee Creek, the eastern section of 5 AVN and the Ingham Road sports fields.

— The waters of Lake Lydeamore returned a PFOS + PFHxS concentration of 6.69 µg/L (SW125), and sediments collected from the channel that discharges water from Lake Lydeamore to Louisa Creek (SD015) reported a PFOS + PFHxS concentration of 0.0017 mg/kg. Concentrations of surface water and sediment were lower in the post-wet season samples than the DSI results.

— The channel that drains the western section of 5 AVN reported surface water PFOS + PFHxS concentrations of 131.0 µg/L (SW019) and 42.5 µg/L (SW123) and sediment PFOS + PFHxS concentrations of 0.125 mg/kg (SD019) and 0.150 mg/kg (SD123). Surface water PFOS + PFHxS concentrations during the post-wet season sampling were higher than the DSI 2017 results, whereas sediment PFOS + PFHxS concentrations during the post-wet season sampling were significantly lower than the DSI results.

— The samples collected downstream from the Ingham Road sports field returned a surface water PFOS + PFHxS concentration of 0.0452 µg/L (SW020) and sediment PFOS + PFHxS concentrations of 0.006 mg/kg (SD020), 0.0039 mg/kg (SD021) and below laboratory LOR (SD021). Concentrations of PFAS were lower in the post-wet season event in both surface waters and sediments.

These results indicate that PFAS impacted surface water is discharging into Louisa Creek from 5 AVN via the drain on the western side of the Base. PFAS impacted surface water is also discharging from Runway 13/31 via Lake Lydeamore during times of flow. Minor quantities of PFAS impacted surface water was identified downstream from the Ingham Road sports fields, which is likely a result of historical PFAS use on the sports fields; however, a background source may also be responsible for the identified PFAS.

Sampling location SW112/SD112 is located downstream of the Mount St John WTP discharge and reported PFOS + PFHxS concentrations in surface water and sediment of 0.302 µg/L and 0.004.1 mg/kg, respectively. Post-wet season PFAS concentrations were slightly higher than the DSI results.

Downstream of the Base, PFAS concentrations in surface water decreased with distance away from the Base, although PFOS + PFHxS was still detected in Louisa Creek at levels above the ecological screening criteria (SW05 – 0.40 and SW206 – 0.16 µg/L) and at elevated levels in sediments (SD206 – 0.0006 mg/kg) up to approximately 5 km downstream of the Base. Post-wet season surface water concentrations of PFOS + PFHxS were higher in SW205 but lower in SW206 in than the DSI results. Sediment PFOS + PFHxS concentrations were slightly higher in post-wet season than the DSI.

MUNDY CREEK

Mundy Creek accepts surface water runoff from potential PFAS source areas on the Base, namely the former fire training ground NQ0054, Fuel Farm 1 NQ0052, domestic area, the eastern side of Runway 01/19 and the eastern section of former fire training ground NQ0105. On-Base surface water samples from this catchment were limited to SW001A, which receives runoff from Fuel Farm 1 NQ0052 and former fire training ground NQ0054; and SW010S, which receives stormwater from the domestic area, including the former Cadet training area.

Surface water PFOS + PFHxS concentrations of 85.4 µg/L and 1.93 µg/L were reported from SW001A and SW010S, respectively. Sediments collected from SD001A reported a PFOS + PFHxS concentration of 0.0807 mg/kg, while SD010 reported a PFOS + PFHxS concentration of 0.0144 mg/kg. Surface water concentrations were higher in the post-wet season event than in the DSI, whereas sediment PFAS concentrations were lower in the post-wet season event.

Surface water sampled from immediately downstream of the domestic area (SW119) recorded a PFOS + PFHxS concentration of 35.8 µg/L. SW121 contained no water at the time of post-wet season event. Sediments collected from SD121 reported a PFOS + PFHxS concentration of 0.0009 mg/kg. SD119 contained no sediment at the time of Seasonal Monitoring investigation. No comparison with DSI surface water sampling results was possible as no surface water was encountered during the DSI program. The PFAS concentration in sediments at SD121 was three orders of magnitude less than in sediments collected from this location during the DSI.


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These results indicate that during periods of flow, PFAS is being transported off-Base by surface waters from former fire training ground NQ0054 and, to a lesser extent, from Fuel Farm 1 NQ0052 and the former Cadet training area.

Surface water and sediment samples collected from the Mundy Creek catchment downstream of the Base during the post-wet season event showed decreasing PFOS + PFHxS concentrations with increasing distance from the Base. Surface water PFAS concentrations decreased from 32.3 µg/L at SW117, approximately 650 m from the domestic area, to 1.84 µg/L at SW115, approximately 1,600 m from the Base, and PFAS concentrations in sediments decreased from 0.0878 mg/kg to 0.0656 mg/kg at the corresponding sampling points. Surface water and sediments collected from SW109 and SD109 at the mouth of Mundy Creek reported PFOS + PFHxS concentrations of 0.275 µg/L and 0.0043 mg/kg, respectively. PFOS + PFHxS concentrations in surface water and sediment were higher in the post-wet season event at all locations.

These results indicate PFAS is being transported in surface water at concentrations in exceedance of the adopted human health and ecological screening levels (HEPA 2018). Attenuation or dilution of PFAS is likely occurring in this watercourse, possibly through the adsorption of PFAS onto organic matter, which is abundant in the collected sediments.

PFOS + PFHxS was detected in samples collected in the tributary that drains the eastern side of Runway 01/19 (SW113 – 8.41 µg/L and SD113 – 0.243 mg/kg). These concentrations were higher than the results gained in the August 2017 event. Due to extensive flooding, SW106/SD106 and SW209/SD209 could not be accessed or sampled. These results indicate PFAS is being transported off-Base at concentrations in exceedance of the human health and ecological screening levels into the Mundy Creek catchment from the eastern and north-eastern sections of the Base.

BOHLE RIVER

Surface water and sediment samples collected from the Bohle River upstream of tidal influence (SW201 and SD201) returned a surface water PFOS + PFHxS concentration of 0.0039 µg/L and a sediment concentration below the laboratory LOR. The detection of PFAS in surface water at these locations demonstrates the presence of an unknown background source of PFAS in the upper Bohle River catchment.

Immediately downstream of the Woodlands Fire Station (SW129 and SD129), surface water and sediment PFOS + PFHxS concentrations were 0.0059 µg/L and 0.0003 mg/kg, respectively. Approximately 3.8 km downstream (SW202 and SD202), PFOS + PFHxS surface water and sediment concentrations increased to 0.278 µg/L and 0.0012 mg/kg, respectively. PFOS + PFHxS concentrations were lower in the post-wet season event than the DSI, except for the surface water concentrations in SW202. These concentrations may be indicative of impact from off-Base PFAS sources in Bohle (Section 3); however, tidal mixing of waters from Louisa Creek upstream into the Bohle River estuary may also be contributing to this impact.

The lower reaches of the Bohle River, downstream of the confluence with Louisa Creek, reported PFOS + PFHxS surface water concentrations of 0.0452 µg/L (SW203) and 0.0232 µg/L (SW204). Sediment PFOS + PFHxS sediment concentrations were 0.0004 µg/kg (SD203) and 0.0006 µg/kg (SD204). Surface water concentrations were higher in the post-wet season event; however, sediment concentrations were lower. PFAS present in the surface water and sediments at these locations indicate that PFAS impact, potentially from the Base but possibly with some background source contribution, reaches as far as the mouth of the Bohle River.

BACKGROUND

Surface water and sediment samples were collected from three background locations (Figure 8, Appendix A). Surface water concentrations of PFOS + PFHxS in surface water from SW211, SW212 and SW213 were 0.0005 µg/L, 0.0156 µg/L and 0.0025 µg/L, respectively. The concentrations of PFOS + PFHxS in sediments from SD211 and SD212 were below the laboratory LOR, and in SD213 were 0.0022 µg/kg. Surface water concentrations were higher in the post-wet season event than the DSI, whereas sediment results were variable. These results indicate that low concentrations of PFAS are common in surface waters and sediments within the greater Townsville area, suggesting the existence of unidentified PFAS sources.


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8.4.6 TEMPORAL VARIATION IN SURFACE WATER AND SEDIMENT

Historical PFAS results for sediments on the Base are limited to published sampling undertaken by GHD (GHD 2011, GHD 2016), and the previous sampling locations are not directly correlated to the DSI (WSP 2018a) and post-wet season sampling locations.

Previous sediment PFOS + PFHxS analysis from the grassed swale that drains former fire training ground NQ0054 returned concentrations from 0.0851 mg/kg to 0.4296 mg/kg (GHD 2011). Concentrations of PFOS + PFHxS in sediment from this area reported during the DSI (WSP 2018a) were 0.107 mg/kg (SD121). Concentrations of PFOS + PFHxS in sediment collected in the post-wet season event from SD121 were only 0.0009 mg/kg.

Historical surface water PFAS data is also intermittent with meaningful long-term data only available at SW013, SW017 and SW019. No trend is discernible at SW013, suggesting surface water PFAS discharge from the Base into the Town Common has remained relatively stable for the past six years. PFAS concentrations have increased in SW019 in the DSI and Seasonal Monitoring (post-wet season) investigations compared with the previous monitoring (Jacobs 2016b); however, PFOS concentrations were relatively stable from 2011 to 2016 (GHD 2011, Jacobs 2016b); therefore, insufficient data exists to determine whether an increasing trend is present at this location. A slight increasing trend in PFAS concentrations is observed in upstream location SW017.

There was no investigation-wide trend between the DSI and the post-wet season surface water or sediment PFAS concentrations (Table 8.6). However, where surface water concentrations had increased, sediment concentrations tended to have decreased, with the opposite relationship also apparent. This reinforces the sediment – water relationship discussed in Section 8.4.3.

Generally, local trends were observed whereby surface waters shedding off source zones showed an increase in surface water PFAS concentrations in post-wet season samples, whereas surface waters in background areas showed a decrease in PFAS concentrations in post-wet season samples. Surface water concentrations were generally higher in the post-wet season event in the Three Mile Creek and Mundy Creek catchments, whereas surface water concentrations in the Louisa Creek and Town Common catchments were generally lower in the post-wet season event. This may be due to the relative contributions to the surface water flow from the Base, with a high proportion of the Mundy Creek and Three Mile Creek flows derived from the Base, whereas Louisa Creek receives a higher proportion of flow from upstream of the Base, with lower PFAS concentrations. The Town Common results may be lower due to dilution from local flooding by rainfall.

However, there are numerous exceptions to the observed trends and the seasonal variation and rainfall response of PFAS concentrations in surface water and sediments at the IA are not well understood. Additional monitoring events would be required to confirm whether observed increases/decreases in surface water and sediments between wet and dry seasons are repeatable or are due to natural variability.


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Table 8.6 Surface water changes in concentrations of PFOS + PFHxS between dry and wet period sampling





CHANGES (µg/L)


On-Base – Mundy Ck catchment

SW001A 67.2 85.4 +18.2

SW010 0.29 1.93 +1.64

SW132 NS 44.4 -

On-Base Louisa Ck Town Common Catchment

SW012 Dry 6.59 -

SW013 14.8 9.5 -5.3

SW015 Dry 0.856 -

SW016 0.5 0.165 -0.335

SW019 58.6 131 +72.4

SW020 Dry 0.0452 -

SW021 0.3 NA -

SW039 29.7 455 +425.3

SW106 27.7 NA -

SW119 Dry 35.8 -

SW123 25.3 42.5 +17.2

SW124 NA 18.6 -

SW125 5.21 6.69 +1.48

SW126 6.84 5.69 -1.15

SW131 NS 4.99 -

On-Base Three Mile Ck catchment

SW103 1.00 1.39 +0.39

SW104 Dry 1.24 -

Off-Base Louisa Ck & Peewee Ck catchment

SW014 0.12 0.065 -0.055

SW017 0.24 0.21 -0.03

SW120 0.26 0.25 -0.01

SW127 0.11 0.0543 -0.0557

SW128 0.10 0.0574 -0.0426

Off-Base Three Mile Ck catchment

SW101 Dry 1.04 -

SW102 0.92 1.38 +0.46

SW107 0.29 0.613 +0.323

SW210 <0.05 0.0764 +0.0264


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CHANGES (µg/L)


Off-Base Mundy Ck catchment

SW108 <0.05 0.335 +0.285

SW109 <0.05 0.275 +0.225

SW113 3.79 8.41 +4.62

SW114 0.07 0.27 +0.20

SW115 0.04 1.84 +1.80

SW116 0.03 0.872 +0.842

SW117 24.9 32.3 +7.40

SW118 10.1 13.2 +3.10

SW208 0.02 0.559 +0.539

Off-Base Town Common

SW110 6.26 6.32 +0.06

SW111 6.06 4.17 -1.89

SW112 0.10 0.302 +0.202

SW205 0.40 0.87 +0.47

SW206 0.39 0.16 -0.23

SW207 0.36 0.39 +0.03

Off-Base Bohle River SW129 0.10 0.0059 -0.0941

SW201 0.005 0.0039 -0.0011

SW202 0.19 0.278 +0.088

SW203 <0.05 0.0452 -

SW204 <0.05 0.0232 -

Background Ross Ck, ALthaus Ck, Alligator Ck & Stuart Ck

SW130 NS 0.246 -

SW211 <0.05 0.0005 -

SW212 <0.05 0.0156 -

SW213 <0.05 <0.05 -

NS – Not sampled

NA – Not accessible


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9 CONCEPTUAL SITE MODEL

9.1 INTRODUCTION A preliminary CSM was developed after the first phase of investigations (desktop and site walkover) to inform the SAQP for the DSI. The CSM was then updated following the drilling and sampling investigations (WSP 2018a) as detailed in Section 4.

Following the receipt and interpretation of results in this Seasonal Monitoring Report 1, the CSM has been updated to provide a description of the current understanding of source-pathway-receptor linkages for PFAS impact in the IA. The HHRA (WSP 2018b) utilised data reported in the Seasonal Monitoring and thus the risk estimates detailed in the HHRA are current to the Seasonal Monitoring.

The CSM has been presented in three parts, representing the three receiving surface water catchments in the IA (Louisa Creek/Town Common/Bohle River; Three Mile Creek; Mundy Creek). A revised graphical representation of the CSM is shown on Figure 23a, Figure 23b and Figure 23c Appendix A.

Sampling and PFAS analysis of aquatic and semi-terrestrial biota was undertaken and reported as a component of the HHRA (WSP 2018b) and ERA (WSP 2019a). PFAS impact in biota is considered in the CSM as a source (ecological) or migration pathway (human health and terrestrial biota) as PFAS was detected in aquatic and semi-terrestrial biota in the IA. The human health implications of the presence of PFAS in aquatic biota were assessed and reported in the HHRA (WSP 2018b).

9.2 PFAS CONTAMINANTS OF POTENTIAL CONCERN All samples submitted for analysis as part of this investigation were analysed for the 28-compound PFAS suite (Golder 2017). All compounds in the suite were detected during the investigation in various media with the exception of EtFOSA. In all investigated media, PFOS and PFHxS returned the highest concentrations, and PFOA was usually detected where PFOS and PFHxS were detected, but at lower concentrations.

Currently, human health and ecological guidelines only exist for PFOS, PFHxS and PFOA, rendering meaningful analysis of the results of the other 24 detected PFAS compounds difficult. In addition, limited information exists on the different behaviours of the other PFAS compounds in soil, sediment, surface water and groundwater. Therefore, for the purposes of this investigation, PFOS, PFHxS and PFOA are considered the COPC, and the behaviours of these three compounds are assumed to be similar in the media investigated.

9.3 SUMMARY OF SOURCES OF CONTAMINATION During the DSI (WSP 2018a), PFAS was detected in all but three soil bores drilled on-Base for the investigation. The highest concentrations were generally associated with previously identified potential source areas; however, the presence of lower concentrations in shallow soils across the Base appears to be almost ubiquitous. Up-gradient PFAS was detected in Louisa and Peewee Creeks and the Bohle River, indicating the potential presence of off-Base PFAS sources in Garbutt and Bohle. However, the relative contribution of PFAS from these background sources is considered minor when compared with the contribution from the Base.

A summary of the sources and significance of PFAS impact in the IA by catchment is provided in Table 9.1.


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Table 9.1 Sources and significance of PFAS impact by IA catchment

CATCHMENT MOST SIGNIFICANT PFAS IMPACT

POTENTIALLY SIGNIFICANT PFAS IMPACT

RELATIVELY MINOR PFAS IMPACT

Louisa Creek / Town Common / Bohle River

Historical fire training at the former fire training ground NQ0106

Historical fire training and AFFF spill at Pad Brahman

Possible emergency responses adjacent to Runway 07/25 and Runway 01/19

Unknown activities, possibly emergency response on a reported fuel spill at Fuel Farm 2 NQ0099

Historical fire training, sparging of fire truck tanks, AFFF spills and storage of PFAS impacted soil at disused Runaway 13/31

Historical fire training activities at former fire training ground NQ0107

Historical fire training, equipment testing and sparging of fire truck tanks and AFFF spills at the fire station NQ0055

Equipment testing and AFFF storage at the 5 AVN wash point (Building 366) and GSE compound

Accidental discharges and spills from AFFF-containing fire deluge systems in hangars (Buildings 236 and 295) at 5 AVN

Historical production and use of foam during open day demonstrations at the Ingham Road sports fields

Mundy Creek Historical fire training and equipment testing and purging at the former fire training ground NQ0054

Historical fire training by cadets and production of foam during open day demonstrations at the former Cadet training area

–

Three Mile Creek – Historical fire training at the former fire training ground NQ0105

–

9.4 MIGRATION PATHWAYS The following migration pathways are considered to have resulted in the transport of PFAS from the Base:

— Discharge/spill of AFFF onto ground, infiltration into soil and sorption to soil and organic matter.

— Discharge or spill of AFFF into drainage channels and flowing off-Base into the catchments of Mundy Creek, Louisa Creek, Peewee Creek, Three Mile Creek and The Common.

— Pumping of impacted surface water from on-Base catchments into the Louisa Creek and Three Mile Creek catchments (typically following a significant rainfall event).

— Sorption of PFAS onto sediment particles which transport off-site during a significant rainfall event.

— Physical transport of sediments off-Base as suspended solids (due to heavy rainfall or maintenance works in drains) in surface water into the Mundy Creek, Louisa Creek, Peewee Creek, Three Mile Creek and the Town Common catchments.


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— Desorption of PFAS from impacted sediments into surface waters of Mundy Creek, Louisa Creek, Three Mile Creek and the Town Common.

— Leaching of PFAS from soils into surface water runoff or vadose zone waters and discharge into drainage channels.

— Vertical migration of PFAS leached from the vadose zone by infiltrating rain/surface water to shallow groundwater.

— Lateral migration of dissolved PFAS with groundwater flow.

— Sorption of PFAS to soil beneath the groundwater table during migration of groundwater – sorbed PFAS will leach with changing groundwater conditions, acting as a secondary source.

— Infiltration of impacted surface water from water bodies under losing conditions (when surface water levels are higher than the groundwater table). This is inferred to occur in the Town Common, Three Mile Creek and the upper and middle reaches of Mundy Creek. This may lead to groundwater impacts with no direct groundwater connection to groundwater impact at the primary source.

— PFAS ingestion by aquatic organisms and bio-magnification in the food web, including the human consumption of fish/seafood.

— Airborne transport of PFAS impacted soil-derived particles.

9.5 EXPOSURE PATHWAYS The following potential exposure pathways have been identified in the IA:

— Ecological receptors in direct contact with PFAS impacted soil, surface water and groundwater. Particularly in the on-Base wetlands, receiving wetlands of the Town Common and Louisa Creek, Peewee Creek, Three Mile Creek and Mundy Creek.

— Biomagnification through the food web.

— Incidental ingestion of on-Base PFAS impacted soil.

— Direct contact (dermal contact and incidental ingestion) with PFAS impacted surface waters and sediments through recreational use (swimming, fishing, crabbing).

— Ingestion of PFAS impacted aquatic organisms (fish, crustaceans, molluscs) through consumption of recreational fishing catch.

— Incidental ingestion or aerosol inhalation of PFAS impacted extracted groundwater from private residential bores through irrigation misting or sprinkler play.

— Consumption of domestically grown plants or animals which are PFAS impacted through irrigation and/or watering with PFAS impacted extracted groundwater from private residential bores.

— Inhalation of soil-derived airborne particulates.


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9.6 POTENTIAL RECEPTORS — On-Base personnel and temporary residents accessing exposed areas of the Base.

— On-Base and off-Base sub-surface maintenance or construction workers.

— On-Base child care or kindergarten attendees.

— Aquatic ecosystems of the Town Common, Louisa Creek, Peewee Creek, Three Mile Creek, Mundy Creek and the Bohle River.

— Terrestrial ecosystems connected with the above aquatic ecosystems (particularly the Town Common) through the food web.

— Recreational users of Mundy Creek, Three Mile Creek, the Town Common and Bohle River.

— Consumers of recreational fishing catch and aquatic organisms (fish, crustaceans, molluscs) collected for consumption from the Town Common, Three Mile Creek, Mundy Creek, Bohle River, Halifax Bay and Rowes Bay.

— Off-Base residential users of groundwater extracted from private groundwater bores for domestic (potable and non-potable) purposes.

9.7 SUMMARY OF SOURCE-PATHWAY-RECEPTOR LINKAGES

A summary of the linkages between identified sources, exposure pathways and sensitive receptors for catchments of Three Mile Creek, Louisa Creek/the Town Common/Bohle River, and Mundy Creek are provided in Table 9.2, Table 9.3 and Table 9.4. A diagrammatical representation of the CSMs are provided as Figures 23a, 23b and 23c Appendix A.


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Table 9.2 Conceptual Site Model for the Three Mile Creek catchment

SOURCE TRANSPORT MECHANISM

ROUTE OF EXPOSURE

POINT OF EXPOSURE

POTENTIAL RECEPTOR

RECEPTOR MEDIA POTENTIALLY COMPLETE PATHWAY

PFAS impacted soils at former fire training ground NQ0105

Surface water discharge off-Base naturally or pumped, PFAS desorbed from sediments into surface water

Direct contact (human health)

Three Mile Creek Recreational user Surface water

Ingestion (human health) Aquatic organisms caught in Three Mile Creek

Consumers of recreation catch

Seafood

Direct contact (ecological)

Three Mile Creek and associated wetlands

Aquatic Ecosystems Surface water

Surface water infiltrating to shallow groundwater

Ingestion (human health) Private groundwater bores

Consumers of groundwater extracted from private groundwater bores

Groundwater (extracted)

Ingestion (human health) Produce or stock grown with water extracted from private groundwater bores

Consumers of produce or stock grown with water extracted from private groundwater bores

Plant matter

Ingestion/aerosol inhalation (human health)

Private groundwater bores

Recreational users of water extracted from private groundwater bores


Sediment dispersed as suspended solids


Three Mile Creek and associated wetlands

Aquatic Ecosystems Sediment

Biomagnification Ingestion (ecological) Aquatic organisms in Three Mile Creek and wetlands

Terrestrial and aquatic predators

Aquatic organisms

Notes: = exposure pathway may potentially be completed (or completed) = exposure pathway considered to be negligible or not considered to be complete (or completed)


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Table 9.3 Conceptual Site Model for the Louisa Creek/Town Common/Bohle River catchment


ROUTE OF EXPOSURE

POINT OF EXPOSURE

POTENTIAL RECEPTOR


PFAS impacted soils at former fire training ground NQ0106, Pad Brahman, Runway 13/31, fire station NQ0055, Fuel Farm 2 NQ0099 and 5 AVN



Bohle River, Louisa Creek, Town Common wetlands

Recreational user Surface water

Ingestion (human health) Aquatic organisms caught in Bohle River, Louisa Creek and the Town Common


Biota - Fish and seafood


Town Common wetlands, Louisa Creek and Bohle River








Fruit and vegetables






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ROUTE OF EXPOSURE

POINT OF EXPOSURE

POTENTIAL RECEPTOR






Biomagnification Ingestion (ecological) Aquatic organisms in Town Common wetlands, Louisa Creek, Mundy Creek and Bohle River


Aquatic species

Groundwater transport Ingestion (human health) Private groundwater bores










Groundwater mixing with surface water





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Table 9.4 Conceptual Site Model for the Mundy Creek catchment


ROUTE OF EXPOSURE

POINT OF EXPOSURE

POTENTIAL RECEPTOR


PFAS impacted soils at former fire training ground NQ0054, former Cadet training area and eastern section of former fire training ground NQ0105

Water and wind erosion, excavation and exposure of soils during excavation activities

Incidental ingestion (human health)

Excavation works, exposed soils, outdoor air

On-Base workers, residents and attendees at kindergarten

Soil


Excavation works, exposed soils, outdoor air

On-Base workers, residents and attendees at kindergarten

Soil



Mundy Creek Recreational user Surface water

Ingestion (human Health) Aquatic organisms caught in Mundy Creek


Biota – fish & seafood


Mundy Creek and associated wetlands










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ROUTE OF EXPOSURE

POINT OF EXPOSURE

POTENTIAL RECEPTOR










Biomagnification Ingestion (ecological) Aquatic organisms in Mundy Creek and associated wetlands


Aquatic species

Groundwater transport Ingestion (human health) Private groundwater bores










Groundwater mixing with surface water





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Where a potentially complete exposure pathway from source to receptor is identified, the next step is to undertake a risk assessment to evaluate the potential for adverse health or ecological effects. The potentially complete pathways identified above are addressed in the separate HHRA (WSP 2018b) and ERA (WSP 2019a).

The results of the Seasonal Monitoring Report 1 were utilised in the HHRA and ERA and the risk assessments are current to this Seasonal Monitoring Report 1.

9.8 AREAS OF UNCERTAINTY At the completion of the DSI (WSP 2018a), a number of areas of uncertainty were identified both on-Base and off-Base. The works reported in the Seasonal Monitoring Report 1 have been designed to address certain data gaps that were considered important to the preparation of the HHRA and ERA. Whilst some data gaps have been closed, as is common with detailed, complex investigations covering a large area, areas of uncertainty still remain that may require further investigation to fully assess the on-Base and off-Base PFAS impacts in the IA.

9.8.1 SOIL ASSESSMENT

Considering the results from the GHD investigation (GHD 2011) for areas that WSP could not access, the soil investigation undertaken during the DSI (WSP 2018a) and the supplementary sampling on the Ingham Road sports fields and eastern site boundary undertaken as part of this Seasonal Monitoring (Section 8.1), it is considered primary PFAS source areas have been suitably identified and targeted to characterise the nature and extent of PFAS impacts and to subsequently assess potential risks to human health and the environment. The data is considered of sufficient robustness and quality to inform the development of the PMAP, thereby achieving the objectives of the assessment. However, the soil investigation is not likely to provide adequate certainty and delineation of the nature and extent of PFAS impact in soil for the development of specific strategies and costs for future management or remediation of each source area (if required).

Soil sampling was undertaken at selected residences in Garbutt, Rowes Bay and Pallarenda to investigate the potential for accumulation of PFAS in soils as a result of irrigating with PFAS impacted groundwater. In most cases these results closed out the potential for human health impact from this pathway (as ‘pathway not complete’). However, three residences (one each in Garbutt, Rowes Bay and Pallarenda) returned PFOS+PFHxS concentrations above the residential HBGVs (maximum 0.573 mg/kg). The PFAS impact is considered to be a result of long-term irrigation with PFAS impacted groundwater, although biomagnification processes in the root zones of fruit trees may be contributing to the elevated PFAS concentrations in some soil samples. These exceedances have been considered in the HHRA (WSP 2018b). Where possible, fruit and vegetable samples were collected from these residences (Section 7.9) and all results were below HBGVs (note that the LOR for PFHxS+PFOS for fruit and vegetables was 0.001 µg/kg, which is above the FSANZ trigger point for fruit (0.0006 µg/kg).

9.8.2 GROUNDWATER ASSESSMENT

On-Base delineation of groundwater impact from specific source areas was not an objective of the investigations. Therefore; uncertainty exists with regards to the extent and severity of groundwater impact beneath the Base.

Vertical delineation of PFAS impact in groundwater has not been advanced at the Base. Hydrogeological conceptualisation of the IA suggests limited connection between the shallow aquifer and deeper aquifers beneath the IA. However, no groundwater bores are known to be screened deeper than the shallow aquifers that were intersected during this investigation. If PFAS impact has infiltrated to intersect the deeper aquifers, no sensitive receptors have been identified and no source-pathway-receptor linkage is considered likely to exist.

The delineation of the PFAS groundwater plume to the south, east and south-east of the Base to below the LOR has not been completed, and uncertainty regarding groundwater flow directions beneath Garbutt exist. The identification of PFAS impact in surface waters and groundwater up-gradient from the Base suggests an unidentified source may exist in


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this area of the IA. The risk posed to sensitive receptors by impacted groundwater to the south, east and south-east of the Base is considered likely to be low and no further delineation investigations are considered warranted in this area.

9.8.3 SURFACE WATER AND SEDIMENT ASSESSMENT

The DSI (WSP 2018a) was conducted during a prolonged dry period, which resulted in several of the surface water locations containing insufficient water for sample collection. Uncertainties also existed regarding the flow directions, rates, volumes, water levels, PFAS concentrations and loads that occur during a wet season or significant rainfall event. The Seasonal Monitoring investigation was conducted immediately after a significant rainfall event during the wet season, and surface water samples were able to be obtained from all of the proposed sample locations. These results have closed the information gap regarding PFAS concentrations during periods of surface water flow on and off-Base, and provide a greater understanding of the interaction of surface water and groundwater during the wet season. Loads are not able to be estimated due to the uncertainties regarding flow rates during the discharge event.

9.8.4 BIOTA

Selected sampling of fruit and vegetables was undertaken at residences who identified that they irrigated their gardens / trees with groundwater, and whose groundwater bore samples returned positive PFAS detections. However, not all species of fruit tree present were fruiting (mangoes). Studies of PFAS uptake into plants have indicated that PFAS accumulation in fruit is lower than in vegetables irrigated with the same water and soil conditions (AECOM 2017). Although this study did not include mangoes, it is considered likely that mangoes irrigated by PFAS-impacted groundwater in the IA are unlikely to contain significant concentrations of PFAS. The HHRA (WSP 2018b) has included an assessment of fruit and vegetable intake in the IA.

9.8.5 PROPOSED FURTHER ASSESSMENT

The following further investigations (not including works being conducted as part of the ERA or PMAP development) may be required to reduce the uncertainties listed above:

— Ongoing monitoring is recommended to identify changes in the PFAS impact over time in the investigation area. An ongoing monitoring plan (OMP) is proposed for inclusion in the PMAP (WSP 2019b).


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10 CONCLUSIONS The objective of this Seasonal Monitoring Report 1 was to close data gaps identified in the DSI (WSP 2018a), with a focus on developing an understanding of how the potential risks to human health and the environment posed by the historical use of AFFF at the Base may have altered following a significant rainfall event. This Seasonal Monitoring Report 1 is the third major deliverable for the project and will inform next stages of work, ultimately contributing to the project objectives being met.

The specific objectives of the Seasonal Monitoring Report 1 were to:

— improve the understanding of the distribution and nature of PFAS impact in, groundwater, surface water and sediments at the Base during times of surface water flow and increased rainfall

— assess the nature and extent of PFAS distribution (if any) in groundwater, surface water and sediments at the location of potential receptors (i.e. within IA), during times of increased surface water flow and increased rainfall

— address data gaps (soils on- and off-Base, fruits and vegetables grown in residences using groundwater for irrigation) identified in the DSI (WSP 2018a)

— update the DSI CSM with the additional data as applicable to PFAS sources, pathways and potentially exposed human and environmental receptors within IA

— generate additional input data for the development of the HHRA and ERA (if required); and — generate additional input data for the development of the PMAP for PFAS impact management within the Base.

10.1 SITE SETTING The Base contains and is surrounded by several features that are considered to be sensitive environmental receptors; the on-Base wetlands; the wetlands on the Town Common; Louisa, Three Mile and Mundy Creeks and associated wetlands; and the Bohle River.

The residential suburb of Garbutt is adjacent to the Base to the east. Industrial land is located to the south and west of the Base in Garbutt and Mount Louisa. Residential groundwater users have been identified in the surrounding suburbs of Garbutt, Belgian Gardens, Rowes Bay and Pallarenda.

Geology and environmental setting are described in the DSI (WSP 2018a).

10.2 PFAS SOURCES (SOIL) As an extension to the PFAS sources identified in the DSI (WSP 2018a):

— Four soil samples collected from the Ingham Road sports fields returned PFAS concentrations below the applicable HBGV (HEPA 2018- Public Open Space). As such, the sports fields have been confirmed as a relatively minor PFAS source area and PFAS in soil and groundwater at this location is not considered to present an unacceptable risk to human health or the environment.

— Two soil samples collected from immediately east of the Base boundary returned PFAS concentrations below the applicable HBGVs (HEPA 2018 – Residential). These samples effectively delineated the shallow soil impact identified on-Base in the domestic area and at Fuel Farm 1 NQ0052.

— Secondary sources of PFAS were identified in soil at some residences in Garbutt, Rowes Bay and Pallarenda. Three samples returned PFOS+PFHxS concentrations above the residential HBGVs. The PFAS impact is considered to be a result of long-term irrigation with PFAS impacted groundwater, although biomagnification processes in the root zones of fruit trees may be contributing to the elevated PFAS concentrations in some soil samples. These exceedances have been considered in the HHRA (2018b) and in this document are considered to present an acceptable human health risk.


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10.3 GROUNDWATER PFAS was detected in groundwater from all sampled monitoring wells on the Base, indicating widespread groundwater impact beneath the Base. During the DSI (WSP 2018a) the absence of PFAS in isolated monitoring wells (MW104, MW140 and MW142) suggested that there was not one continuous PFAS ‘plume’ beneath the Base, but a series of PFAS ‘plumes’ and multiple pathways related to specific source areas and possibly surface water bodies.

Groundwater samples that had previously returned concentrations below the LOR in the DSI were selected for ultra-trace PFAS analysis as part of the post-wet weather sampling. Ultra-trace analysis detected PFAS and as such, has shown that PFAS appears to be ubiquitous in groundwater beneath the Base; although, isolated elevated concentrations are associated with individual source areas.

The detection of PFAS in all off-Base monitoring wells (with the exception of monitoring wells analysed at a higher detection limit – MW202, MW204, MW205, MW207 and MW212) to the north-west, north, north-east, south-east and east of the Base suggests that groundwater ‘plumes’ have transported PFAS off-Base in these directions. However, irregularities in the results, such as the anomalously high results in MW206 and MW216, suggest that the groundwater impacts are not continuous plumes’ in the traditional hydrogeological sense i.e. a relatively homogeneous dissolved mass of chemical with steadily declining concentration away from the primary source. Elevated concentrations of PFAS in groundwater at a distance from the Base are considered more likely to be a result of surface water PFAS transport with subsequent infiltration of PFAS impacted water into the underlying aquifer.

The discharge monitoring undertaken during March 2018 (Section 10.4) supports this theory, with large volumes of surface water with relatively high concentrations of PFAS observed to be draining off the Base into the surface water bodies of the Town Common and the Three Mile Creek and Mundy Creek catchments.

The groundwater impact to the south and south-east of the Base is considered likely to be the result of an unidentified off-Base source. The wet season results have reinforced this theory and additional investigations are not considered warranted as the risk posed to sensitive receptors by impacted groundwater in this area is considered to be low.

10.4 SURFACE WATER AND SEDIMENTS Discharge sampling conducted immediately following the significant rainfall event in March 2018 returned results indicating that during periods of significant rainfall, PFAS impacted surface water is being discharged from the Base into the Louisa Creek, Town Common, Three Mile Creek and Mundy Creek catchments at concentrations generally in excess of the recreational HBGV. PFAS concentrations remained relatively constant at three locations during the five days of sampling; however, concentrations increased significantly at the discharge point into Louisa Creek on the fourth day of sampling. This may be a result of impacted groundwater daylighting into the drainage channel following a rise in the groundwater table as a direct result of the rainfall event.

PFAS was detected in surface water and sediment on- and off-Base at concentrations in exceedance of the nominated guidelines during the post-wet season sampling event. The results indicate that PFAS is being transported by surface waters from the Base into the Town Common, Louisa Creek, Three Mile Creek and Mundy Creek catchments. Significant volumes of water were flowing off the Base during the rainfall event in March 2018; however, at the time of the post-wet season monitoring event (April 2018) surface water flow from the Base had ceased.

During times of high flow it was observed that PFAS impacted water and, to a lesser extent physically transported sediments, are discharged from the Base. It is unclear whether the PFAS impacted sediments found at a distance from the Base have been transported to those locations, or whether dissolved phase PFAS has been transported to the location and then bound to the sediments.

Results of samples collected up-gradient of the Base indicate a potential background source of PFAS exists in the upper catchments of Louisa and Peewee Creeks and in the middle reaches of the Bohle River. However, compared with the concentrations recorded in surface waters discharging from the Base, the background up-gradient input of PFAS concentrations to the IA as a whole, is considered to be minor.


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10.5 BIOTA No PFAS was detected in any of the fruit samples and PFOS was only detected in one sample of spinach at a concentration of 0.002 mg/kg. These results were used in the HHRA (WSP 2018b), which identified a low and acceptable health risk associated with the ingestion of home-grown fruit and vegetables in the IA.

10.6 COMPARISON OF DRY AND WET SEASON PFAS CONCENTRATIONS

PFAS concentrations in the post-wet season monitoring groundwater samples were generally higher than in the DSI results; however this trend was not consistent, with 29% of locations recording lower PFAS concentrations than the corresponding DSI samples.

PFAS concentrations in surface water were generally slightly higher in the post-wet season sampling event than in the DSI. Sediment PFAS concentrations did not show an obvious trend.

10.7 CONCEPTUAL SITE MODEL The CSM identifies the following receptors that are considered to be potentially at risk from Base-derived PFAS impact due to a complete source-pathway-receptor linkage:

— on-Base workers, residents and attendees at the kindergarten from incidental ingestion of impacted air borne particles and exposed soils

— on-Base workers, residents and attendees at the kindergarten from direct contact with impacted air borne particles and exposed soils

— recreational users of Three Mile Creek, The Town Common, Louisa Creek, Bohle River and Mundy Creek from direct contact with impacted surface water

— consumers of impacted aquatic organisms caught recreationally from Three Mile Creek, Louisa Creek, Bohle River and Mundy Creek

— recreational users of water extracted from private groundwater bores in the Garbutt area from incidental ingestion and aerosol inhalation of impacted groundwater

— aquatic ecosystems of The Town Common, Three Mile Creek, Louisa Creek, Bohle River and Mundy Creek through direct contact with impacted surface water, sediments and discharged groundwater; and

— terrestrial and aquatic predators of the Town Common, Louisa Creek, Bohle River and Mundy Creek and associated wetlands.

Where a potentially complete exposure pathway from source to receptor is identified, the next step is to undertake a risk assessment to evaluate the potential for adverse health or ecological effects. The potentially complete pathways identified above are addressed in the separate HHRA (WSP 2018b) and ERA (WSP 2019a), inclusive of results presented in this Seasonal Monitoring Report 1.


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10.8 ONGOING WORKS Based on the findings of the DSI, the following works have been triggered and have been completed:

— a HHRA (WSP 2018b) has been completed and published on the Defence website (http://www.defence.gov.au/Environment/PFAS/docs/Townsville/Reports/HumanHealthRiskAssessmentReportBody.pdf). The HHRA assesses potential risk to human health associated with the potentially complete source-pathway-receptor exposure linkages identified in the CSM

— an ERA (WSP 2019a) has been completed to assess potential risk associated with the potentially complete ecological source-pathway-receptor exposure linkages identified in the CSMs; and

— a PMAP (WSP 2019b) has been completed to provide management plans to mitigate the potential impact to human health and the environment from identified PFAS in the IA and to mitigate the potential migration of PFAS off-Base. The PMAP will contain an ongoing PFAS monitoring plan for the Base and IA.


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11 LIMITATION STATEMENT: ENVIRONMENTAL SITE ASSESSMENT

This Report is provided by WSP Australia Pty Limited (WSP) for the Commonwealth of Australia as represented by the Department of Defence (Client) in response to specific instructions from the Client and in accordance with the Deed of Standing Offer with the Client dated 10 October 2016 (Deed).

PERMITTED PURPOSE

This Report is provided by WSP for the purpose described in the Deed and no responsibility is accepted by WSP for the use of the Report in whole or in part, for any other purpose (Permitted Purpose). No responsibility is accepted by WSP for the use of the Report in whole or in part for any purpose, goal, interest, need, circumstance or project other than the Permitted Purpose

QUALIFICATIONS AND ASSUMPTIONS

The services undertaken by WSP in preparing this Report are limited to those specifically detailed in the Report and are subject to the scope limitations set out in the Report. The findings contained in the Report are subject to the qualifications and assumptions set out in the Report or otherwise communicated to the Client.

Except as otherwise stated in the Report and to the extent that statements, opinions, facts, conclusion and / or recommendations in the Report (Conclusions) are based in whole or in part on information provided by the Client and other parties identified in the report, those Conclusions are based on assumptions by WSP of the reliability, adequacy, accuracy and completeness of the Information and have not been verified. WSP accepts no responsibility for the Information.

The Conclusions are reflective of the current Site conditions and cannot be regarded as absolute without further extensive intrusive investigations, outside the scope of the services set out in the Deed and are indicative of the environmental condition of the Site at the time of preparing the Report. As a general principle, vertical and horizontal soil or groundwater conditions are not uniform. No monitoring, common or intrusive testing or sampling technique can eliminate the possibility that monitoring or testing results or samples taken, are not totally representative of soil and / or groundwater conditions encountered at the Site. It should also be recognised that Site conditions, including subsurface conditions can change with time due to the presence and concentration of contaminants, changing natural forces and man-made influences.

Within the limitations imposed by the scope of the services undertaken by WSP, the monitoring, testing (intrusive or otherwise), sampling for the preparation of this Report has been undertaken and performed in a professional manner in accordance with generally accepted practices, using a degree of skill and care ordinarily exercised by reputable environmental consultants under similar circumstances. No other warranty, expressed or implied, is made.

WSP has prepared the Report without regard to any special interest of any person other than the Client when undertaking the services described in the Deed or in preparing the Report.

USE AND RELIANCE

This Report should be read in its entirety and must not be copied, distributed or referred to in part only. The Report must not be reproduced without the written approval of WSP. WSP will not be responsible for interpretations or conclusions drawn. This Report (or sections of the Report) should not be used as part of a specification for a project or for incorporation into any other document without the prior agreement of WSP.

WSP is not (and will not be) obliged to provide an update of this Report to include any event, circumstance, revised Information or any matter coming to WSP’s attention after the date of this Report. Data reported and conclusions drawn


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are based solely on the information made available to WSP at the time of preparing the Report. The passage of time, manifestations of latent conditions or impact of future events (including (without limitation) changes in legislation, guidelines, scientific knowledge), may require further investigation or subsequent re-evaluation of the Conclusions.

The Report does not purport to recommend or induce a decision to make (or not make) any purchase, disposal, investment, divestment, financial commitment or otherwise. It is the responsibility of the Client to accept (if the Client so chooses) the Conclusions and implement any recommendations in an appropriate, suitable and timely manner.

In the absence of express written consent of WSP, no responsibility is accepted by WSP for the use of the Report in whole or in part by any party other than the Client for any purpose whatsoever. Without the express written consent of WSP, any use which a third party makes of this Report or any reliance on (or decisions to be made) based on this Report is at the sole risk of those third parties without recourse to WSP. Third parties should make their own enquiries and obtain independent advice in relation to any matter dealt with or conclusions expressed in the Report.

DISCLAIMER

No warranty, undertaking or guarantee whether expressed or implied, is made with respect to the data reported or the conclusions drawn.

To the fullest extent permitted at law, WSP, its related bodies, corporate and its officers, employees and agents assumes no responsibility and will not be liable to any third party for, or in relation to, any losses, damages or expenses (including any indirect, consequential or punitive losses or damages or any amounts for loss of profit, loss of revenue, loss of opportunity to earn profit, loss of production, loss of contract, increased operational costs, loss of business opportunity, site depredation costs, business interruption or economic loss) of any kind whatsoever, suffered or incurred by a third party.


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12 REFERENCES — AECOM, 2012, RAAF Base Townsville 5th Aviation Regiment, Facility 271, Pre-Works Contamination Assessment,

6 December 2012.

— AECOM 2013a, RAAF Base Townsville 5th Aviation Regiment Pollution Control Project (NQ2305) Pre-Works Contamination Assessment - Addendum relating to Excavations to the East of Hanger 295, 29 April 2013.

— AECOM 2013b, RAAF Base Townsville 5th Aviation Regiment Pollution Control Project (NQ2305) Pre-Works Contamination Assessment - Addendum relating to Excavations to the West of Hanger 295, 29 April 2013.

— AECOM 2015, Town Common Rehabilitation and Maintenance Management, Mt St John WWTP, 10 November 2015.

— AECOM 2016a, Spoil Management Plan - Part B, Defence DFI Remediation, RAAF Base Townsville, 8 February 2016.

— AECOM 2016b, email: RFI NQ - Spill Pond Update (RAAF TVL), 1 April 2016.

— AECOM 2016c, Stage 2B Environmental Investigation Report RAAF Base Williamtown, Williamtown NSW, 30 June 2016, Revision 1.

— AECOM 2017, Off-Site Human Health Risk Assessment, December 2017. RAAF Base Williamtown, Stage 2B Environmental Investigations. 1 December 2017, Revision 1 – Final.

— ANZECC & ARMCANZ 2000, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, National Water Quality Management Strategy, Australian & New Zealand Environment & Conservation Council and Agriculture & Resource Management Council of Australia and New Zealand.

— Bureau of Meteorology 2018, viewed 1 November 2018, http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type=dailyDataFile&p_startYear=&p_c=&p_stn_num=032040.

— CONCAWE 2016, Environmental fate and effects of poly- and perfluoroalkyl substances (PFAS), CONCAWE Report No. 8/16, CONCAWE Soil and Groundwater Taskforce, Brussels, Belgium, June 2016.

— CRC CARE 2017, Assessment, management and remediation guidance for perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), CRC CARE Technical Report no. 38, CRC for Contamination Assessment and Remediation of the Environment, Newcastle, Australia.

— Department of Defence 2012, Defence Contamination Directive #7, Naming Convention – Surface Water, Groundwater Bore, Soil and Sediment Sampling Identification, 27 July 2012.

— Department of Defence 2016, PFAS Guidance Document A: PFAS Source and Receptor Identification Framework, November 2016.

— Department of Defence 2017a, Defence Contamination Directive #8 (Amendment 2) Screening Criteria, Defence Project Guidance for Per- and Poly-Fluoroalkyl Substances (PFAS), May 2017.

— Department of Defence 2017b, PFAS Guidance Document D: Non PFAS Analysis of Other Chemicals of Potential Concern, February 2017.

— Department of Defence 2018, PFAS Guidance Document E: Standard PFAS Analytical suite for Detailed Site investigations, March 2018.

— Department of Environment and Energy 2016, Draft Commonwealth Environmental Management Guidance on Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA), October 2016.

http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type=dailyDataFile&p_startYear=&p_c=&p_stn_num=032040

http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type=dailyDataFile&p_startYear=&p_c=&p_stn_num=032040


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— Department of Environment and Heritage Protection 2009a, Monitoring and Sampling Manual 2001, Version 2, July 2013.

— Department of Environment and Heritage Protection 2009b, Queensland Water Quality Guidelines, Version 3, July 2013.

— Department of Environment and Heritage Protection 2013, Ross River Basin and Magnetic Island Environmental Values and Water Quality Objectives, August 2013.

— Department of Environment and Heritage Protection 2018, Queensland Auditor Handbook for Contaminated Land. Module 6: Content requirements for contaminated land investigation documents, certifications and audit reports, July 2018.

— Department of Health 2017, Final Health Based Guidance Values for PFAS for use in site investigations in Australia.

— Department of Infrastructure, Local Government and Planning 2017, State Planning Policy Interactive Mapping System, accessed 21 July 2017 <https://spp.dsdip.esriaustraliaonline.com.au/geoviewer/map/planmaking>

— Department of Mines and Energy 1997. Australia 1:250,000 Geological Series, Townsville, Queensland, Sheet SE 55-14, DME, Mercury-Walch, Hobart.

— Department of National Parks, Recreation, Sport and Racing 2012, Bohle River Fish Habitat Area, DNPRSR, Brisbane.

— Department of Natural Resources and Mines 2017, Groundwater Database, accessed via Queensland Globe, viewed 21 July 2017, <https://qldglobe.information.qld.gov.au/>

— Domenico, PA & Schwartz, FW 1990, Physical and Chemical Hydrogeology, Volume 1. John Wiley & Sons, New York.

— enHealth 2016, enHealth Statement: Interim National Guidance on Human Health Reference Values for Per- and Poly-Fluoroalkyl Substances for Use in Site Investigations in Australia, June 2016.

— ENSR 2008, Groundwater Sample Report for RAAF Base Townsville – Sampled 8 – 18 July 2008, July 2008.

— ENSR 2009a, Groundwater Sample Report for the former Rowes Bay Landfill – Sampled 10 November 2008, November 2008.

— ENSR 2009b, Groundwater Sample Report for RAAF Base Townsville – Sampled 3 – 7 November 2008, March 2009.

— ENSR 2009c, Water Monitoring Program for RAAF Base Townsville, Annual Report (NQ1998), May 2009.

— ENSR 2009d, RAAF Townsville Environmental Monitoring Program for Water Quality (NQ1998), May 2009.

— ERM 2005, Groundwater Quality Monitoring Report: RAAF Base Townsville and Rowes Bay Landfill Site, February 2005.

— FSANZ 2017, Perfluorinated Chemicals in Food, Food Standards Australia and New Zealand.

— GHD 2009, Report for MRH-90 Facilities Upgrade, Site Contamination and Acid Sulfate Soil Assessment, May 2009.

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— Golder Associates 2012b, Townsville RAAF Base MRH Stage 6 - AFFF Assessment, Structure 271, 31 August 2012.

— Golder Associates 2017, Technical Memorandum Laboratory Analysis Suite, 30 March 2017.

— HEPA 2018, PFAS National Environmental Management Plan, Heads of EPAs Australia and New Zealand (HEPA), January 2018.

— Houtz EF and Sedlak DL, 2012, Oxidative Conversion as a Means of Detecting Precursors to Perfluoroalkyl Acids in Urban Runoff, Environmental Science and Technology, 46, 9342 – 9349.

— Jacobs 2016a, North Queensland Water Quality Monitoring, Department of Defence, RAAF Townsville Groundwater Monitoring Report, Post Dry Season, 1 September 2016.

— Jacobs 2016b, North Queensland Water Quality Monitoring, Department of Defence, RAAF Townsville Groundwater Monitoring Report, Post Wet Season, 1 September 2016.

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— Maunsell 2005, Stage 1 Environmental Investigation RAAF Base Townsville, December 2005.

— National Environment Protection Council 2013, National Environmental Protection (Assessment of Site Contamination) Amendment Measure 1999 (No.1), NEPC, Canberra.

— NHMRC & NRMMC 2011, Australian Drinking Water Guidelines Paper 6 National Water Quality Management Strategy, National Health and Medical Research Council, National Resource Management Ministerial Council, Commonwealth of Australia, Canberra.

— NRA 2012a, NQ2340, Surface Water Sample Report for RAAF Base Townsville, March 2012.

— NRA 2013, Surface Water Monitoring, NQ2809.01 - RBT (0874) Relocation of Contaminated Soils, 22 November 2013.

— NRA 2014, NQ2802 Surface Water Sample Report for RAAF Townsville, 2 February 2017, 4 March 2014.

— NSW Environment Protection Authority (EPA) 2016, Guidance Note: Designing Sampling Programs for Sites Potentially Contaminated by PFAS, November 2016.

— NSW Office of Environment and Heritage (OEH) 2017, Draft PFAS Screening Criteria (May 2017), Contaminants and Risk, Environment Protection Science Branch, May 2017.

— NUDLC 2012, Minimum Construction Requirements for Water Bores in Australia, Third Edition. National Uniform Drillers Licencing Committee. West Lakes, South Australia, February 2012.

— Rollason, SN & Howell, S 2012, Aquatic Conservation Assessments (ACA), using AquaBAMM, for the non-riverine wetlands of the Great Barrier Reef catchment, Version 1.3. Department of Environment Resource Management, Brisbane.

— SKM 2008, RAAF Base Townsville, Department of Defence Stage 2 Environmental Investigation, May – June 2008.

— SMEC 2012a, RAAF Base Townsville Airfield Drainage Works – Desktop Environmental Assessment, June 2012.

— SMEC 2012b, NQ2114-RBT/0874 CF3P2 RAAF Base Townsville Drainage Works Airfield, Phase 1, October 2012.

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— Townsville City Council 2014. Townsville City Plan (Version 2017/04).

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— United States Environmental Protection Agency 2014, Emerging contaminants – perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), Emerging contaminants fact sheet – PFOS and PFOA, viewed 23 July 2017, <www2.epa.gov/sites/production/files/2014-04/documents/factsheet_contaminant_pfos_pfoa_march2014.pdf>.

— Wang Z, DeWitt J, Higgens C, Cousins I 2017, A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFAS)?, Environmental Science and Technology, 51, 2508-2518.

— Woodward and Clyde 1999, RAAF Base Townsville Redevelopment Environmental Impact Assessment, Volumes 1 & 2, 1999.

— WSP 2017, RAAF Base Townsville: Comprehensive Investigation of PFAS. Sampling, Analysis and Quality Plan: Version 3, May 2017 (reference 2270642A-CLM-REP-001 REV4).

— WSP 2018a, RAAF Base Townsville Detailed Site Investigation – PFAS, Volume 1: Main Report, May 2018 (Final – reference PS102571-ENV-REP-002 RevD_Vol 1-Main Report).

— WSP 2018b, RAAF Base Townsville Human Health Risk Assessment, October 2018 (Final – reference PS102571-CLM-REP-004 Rev I Main Report).


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RAAF Base Townsville - Seasonal Monitoring Report 1 - PFAS€¦ · 4.2 dsi csm ... 8.3.1 source area impacts..... 104 8.3.2 off-base impacts..... 107 8.3.3 interpreted plume of groundwater