Environmental Audit Report for Shell of 38 McMinn Street Darwin - Aug 2014

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Shell Company Australia

Environmental Audit Report

38 McMinn Street, Darwin, NT

August 2014

Statement of Environmental Audit
Zone A

This Statement provides a summary of the findings of an Environmental Audit of Zone A of the property located at 38 McMinn Street, Darwin, Northern Territory in accordance with Section
47d of the Waste Management and Pollution Control Act (NT). The site is defined on Figure 1 in
Statement - Attachment A.

Name of Auditor Dr Peter Nadebaum

Term of appointment of Auditor 16 May 1990 to 25 September 2015

Date Audit requested 11 June 2010

Owners of the site Shell Company of Australia Limited

Person requesting a Certificate Peter Oxnam of Shell Company of Australia Limited
(SCOA)

Planning Authority Development Consent Authority

Title Information Lot 5649, Town of Darwin

Area of the Site 23329 m²

Zoning Central Business under the Northern Territory Planning
Scheme

Address of the Site McMinn Street, Darwin, Northern Territory

Current Occupier Unoccupied

Site Assessor URS Australia Pty Ltd (URS)

Audit Completion Date 4 August 2014

The audit has had regard to, amongst other things:

 The Waste Management and Pollution Control Act NT 1998.

 The National Environmental Protection Measure for Assessment of Site Contamination
1999 (NEPM, 1999).

 The NT Water Act 1992.

 Advice provided by the Northern Territory Environment Heritage & Arts Division, Department of Natural Resources Environment & the Arts (EHA/DNRETA).
 The general principles for undertaking audits, as outlined by Part IXD of the Victorian
Environment Protection Act, 1970, and the associated policies and guidelines.

Summary of findings

The site was held as Crown land and unoccupied in its natural state until Shell purchased the site circa 1930 and commenced operation as the Shell Terminal in 1937. The site was established for bulk storage and handling of hydrocarbon products. Remediation of the Site has been undertaken to the extent practicable and to make the Site suitable for future development. The development and ongoing use of the Site is subject to certain conditions and the Site Contamination Management Plan (SMP) and Groundwater Quality Management Plan (GQMP) attached to this Statement of Environmental Audit.

The following information is relevant regarding the condition of the Site:

 All on site infrastructure potentially containing hydrocarbons including ASTs, USTs, loading gantries, valve exchanges and associated product delivery lines were decommissioned and removed from site in 2005/2006.

Soil

 Large portions of hydrocarbon impacted unconsolidated material in the lower site area were excavated (in Areas 2 and 3). Land farming of hydrocarbon contaminated soil was carried out to reduce the mass of hydrocarbon contamination in the impacted unconsolidated material through the central portion of the Site (Areas 2 and 3).

 During the Site works undertaken in 2011, fragments of suspected asbestos containing material were observed and in Area 1. This material was removed and validated. Visual inspection for ACM was undertaken across other areas of the site at the time of site surface vegetation removal and observation, and there was no evidence of fragments of asbestos containing material remaining at the site.

 Soil hydrocarbon impacts remain at the top of and within the bedrock in areas closely associated with former infrastructure across the Site. The risk posed by this residual contamination has been assessed, and it is concluded that the site is not suitable for unrestricted sensitive use, and restrictions on allowable building types have been defined in the SMP.

 The site has been divided into five (5) development zones (Zones A to E) that correspond to certain types of development that are acceptable in view of the remaining contamination. The zones are shown in Figure 1 of Statement Attachment A. It is noted:

– The restrictions placed on development in each of the zones are precautionary, and it is possible that other development scenarios or land uses may be allowable either through the use of engineering controls, or if further more intensive sampling is undertaken that confirms that the residual contamination does not pose an unacceptable risk to the proposed land use. It is noted that natural degradation of the residual hydrocarbon contamination continues to occur, and it is possible that in the future the residual concentrations will not pose a risk to more sensitive uses.
– If the use of engineering controls is proposed to reduce risks and allow other land uses, the proposed controls should be reviewed by an environmental auditor.
– If further soil, soil vapour or groundwater sampling is undertaken to define the residual contamination, the results should be compared to the criteria listed in this report, or other risk-based criteria developed by an appropriately experienced and qualified specialist in risk assessment, and the conclusions reviewed and confirmed by an environmental auditor.
 With respect to below ground works, the assessment has concluded that the residual contamination does not pose an unacceptable risk to persons working above bedrock level. It is noted:

– The SMP requires that, if works are proposed to be undertaken within bedrock, consideration be given to the engagement of an appropriately qualified and experienced environmental consultant to assess potential for contamination within bedrock fractures and zones of weathering.
 Hydrocarbon odours may be observed during excavations or construction in parts of the site previously impacted when the soil is disturbed (such as in the north-eastern corner of the site); however, it is expected that odorous material will be minor, limited in extent, and the odours will be transitory.

 This report included an assessment for the potential for UXO which found no evidence that explosive ordnance had impacted the site, and that the risk rating for the site was low, refer to Section 6.5.4. The work undertaken to assess contamination has included field surveys and extensive intrusive environmental investigations during 2006, 2008 and
2011, including broad scale excavation over areas of unconsolidated material and outcropping bedrock. This work did not identify material that would suggest that impact from EO or UXO is present.

Groundwater

 There are four plumes of dissolved phase groundwater contamination beneath the site, three of which overlap in the northern section of the site (Area 2).

 The TDS of the groundwater is low (<1000 mg/L) making it potentially suitable for all beneficial uses, however yield is low and the nature of the development and location of the site in the Darwin CBD (with reticulated water supply) means that uses such as agricultural/irrigation, primary contact recreation, potable and industrial uses are unlikely to occur. The auditor has been previously advised by the NT Government that these beneficial uses do not require protection within the Darwin CBD, and the auditor has assumed that these beneficial uses of groundwater are not relevant at the site.

 Plumes 1, 2 and 4 do not pose an unacceptable risk for residents and commercial
workers for the various residential and commercial building scenarios that were modelled.

 Plume 3, located in the northern portion of the site (centred around the former footprint of AST2), can give rise to concentrations of volatile contaminants that may exceed acceptable levels for residents living on the ground floor of a slab-on- ground residential building and to occupational workers working in a slab-on-ground commercial building. Because of this, the development of the area of the site in the vicinity of MW07 and MW207 will be restricted and designated as open space. This area has been defined as Development Zone E.

The auditor concludes that, with the restrictions on land use in this area as proposed by URS, volatile contamination in groundwater will not pose an unacceptable risk to residents or commercial workers.

 Minor groundwater impact has been observed offsite to the north and north east.
Monitoring has shown that the impact is localised and restricted to an area close to the site boundary, and is stable and not migrating towards the Bay.

 The land down-gradient of the site to the north and north-east is vacant Crown Land and zoned Proposed Main Road. The auditor consulted with the relevant Government planning department to determine the potential for development of this land. The Department noted that it potentially could be developed for a range of uses, but is a natural drainage area. The auditor advised that localised contamination close to the boundary might require controls if development were to involve basements.

 In their letter dated 23 May 2014 (Appendix B), the NT EPA requested that “In relation to the adjacent lots, Barneson Street Road Reserve and Crown Land Lot 6663, that have residual groundwater impact, Shell make formal written notification to the Department of Transport and the Department of Land, Planning and the Environment informing them of the status of the groundwater impact and the statement of environmental audit and associated conditions”.

 Consideration has been given as to whether further clean up should take place. It has been determined that clean up has been carried out to the extent practicable, and NT EPA has advised that it has reviewed the report and is in agreement with the proposed actions.

 As groundwater contamination remains at the site and further clean up of this contamination will be achieved through the process of monitored natural attenuation, ongoing groundwater monitoring will be required until it has been confirmed that the contamination is reducing and the risk is such that further monitoring is not necessary. A Groundwater Quality Management Plan (GQMP) has been prepared by URS and is attached as Appendix B of the SMP (attached as Statement Attachment B of this report).

A site contamination management plan (SMP) has been prepared to outline site management practices which will ensure residual contamination does not cause adverse impact on human health, the environment or otherwise affect the amenity of the site. The SMP includes guidance for future owners of the site including:

 Soil excavation and intrusive works.

 Groundwater abstraction and incidental contact.

 Property management activities.

The Groundwater Management Plan provides information on the requirements for ongoing monitoring of groundwater at the Site.

Note that this audit considers only contamination of the soil and groundwater by potentially hazardous substances, and does not consider or advise on geotechnical conditions, suitability of soil and fill for planting from the perspective of nutrient content and physical form, the possible presence of unexploded ordnance, and other aspects of the suitability of the land for development that are not related to hazardous substances.

Suitability of the site – Zone A

On the basis of the work undertaken, the auditor is of the opinion that the Site (Zone A) is suitable for the intended purpose, that being a development of high density residential and/or commercial retail/office space as outlined in the site contamination management plan (Attachment B) comprising:

 High density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

1. All future development and maintenance works at the site involving excavation, and disposal of soil and fill shall be carried out in accordance with the Site Contamination Management Plan (Attachment B).

2. All garden areas shall be backfilled with at least 1.0 metre of clean fill/topsoil.

3. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

4. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring
Other related information:

The reader should note that the SMP and GQMP are subject to review and will be updated as appropriate. The GQMP is expected to cover a minimum period of four years. After this time it may be reviewed and updated, and in this instance the SMP and GQMP attached to this statement may be superseded.

The limitations outlined in Section 1.7 of this report should be referred to. DATED: 4 August 2014
SIGNED:

PETER NADEBAUM

Environmental Auditor (Appointed Pursuant to the Victorian Environmental Protection Act 1970) and recognised in the Northern
Territory under section 68 of the Waste Management and Pollution Control Act (NT). Statement Attachment A: Site Development Zones and restrictions
Statement Attachment B Site Contamination Management Plan (SMP) – Current version as at 16/7/2014

Statement of Environmental Audit
Zone B

This Statement provides a summary of the findings of an Environmental Audit of Zone B of the property located at 38 McMinn Street, Darwin, Northern Territory in accordance with Section
47d of the Waste Management and Pollution Control Act (NT). The site is defined on Figure 1 in
Statement Attachment A.

Name of Auditor Dr Peter Nadebaum

Term of appointment of
Auditor

16 May 1990 to 25 September 2015

Date Audit requested 11 June 2010

Owners of the site Shell Company of Australia Limited

Person requesting a
Certificate

Peter Oxnam of Shell Company of Australia Limited (SCOA)

Planning Authority Development Consent Authority

Title Information Lot 5649, Town of Darwin

Area of the Site 2231 m²

Zoning Central Business under the Northern Territory Planning
Scheme

Address of the Site McMinn Street, Darwin, Northern Territory

Current Occupier Unoccupied

Site Assessor URS Australia Pty Ltd (URS)

Audit Completion Date 4 August 2014

The audit has had regard to, amongst other things:

 The Waste Management and Pollution Control Act NT 1998.

 The National Environmental Protection Measure for Assessment of Site Contamination
1999 (NEPM, 1999).

 The NT Water Act 1992.

Summary of findings

The following information is relevant regarding the condition of the Site:

Soil

Groundwater

 There are four plumes of dissolved phase groundwater contamination beneath the site, three of which overlap in the northern section of the site (Area 2).

 Plumes 1, 2 and 4 do not pose an unacceptable risk for residents and commercial
workers for the various residential and commercial building scenarios that were modelled.

 Soil excavation and intrusive works.

 Groundwater abstraction and incidental contact.

 Property management activities.

The Groundwater Management Plan provides information on the requirements for ongoing monitoring of groundwater at the Site.

Suitability of the site – Zone B

On the basis of the work undertaken, the auditor is of the opinion that the Site (Zone B) is suitable for the intended purpose, that being a development of high density residential and/or commercial retail/office space as outlined in the site contamination management plan (Attachment B) comprising:

 High density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

1. Buildings must be constructed above open ground level parking

2. No slab on grade

3. No basement car parks

5. All garden areas shall be backfilled with at least 1.0 metre of clean fill / topsoil

6. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

7. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring
Other related information:

The limitations outlined in Section 1.7 of this report should be referred to. DATED: 4 August 2014
SIGNED:

PETER NADEBAUM

Statement of Environmental Audit
Zone C

This Statement provides a summary of the findings of an Environmental Audit of Zone C of the property located at 38 McMinn Street, Darwin, Northern Territory in accordance with Section
47d of the Waste Management and Pollution Control Act (NT). The site is defined on Figure 1 in
Statement Attachment A.

Name of Auditor Dr Peter Nadebaum

Term of appointment of
Auditor

16 May 1990 to 25 September 2015

Date Audit requested 11 June 2010

Owners of the site Shell Company of Australia Limited

Person requesting a
Certificate

Peter Oxnam of Shell Company of Australia Limited (SCOA)

Planning Authority Development Consent Authority

Title Information Lot 5649, Town of Darwin

Area of the Site 21,668 m²

Zoning Central Business under the Northern Territory Planning Scheme

Address of the Site McMinn Street, Darwin, Northern Territory.

Current Occupier Unoccupied

Site Assessor URS Australia Pty Ltd (URS)

Audit Completion Date 4 August 2014

The audit has had regard to, amongst other things:

 The Waste Management and Pollution Control Act NT 1998.

 The National Environmental Protection Measure for Assessment of Site Contamination
1999 (NEPM, 1999).

 The NT Water Act 1992;

 Advice provided by the Northern Territory Environment Heritage & Arts Division, Department of Natural Resources Environment & the Arts (EHA/DNRETA), and

 The general principles for undertaking audits, as outlined by Part IXD of the Victorian
Environment Protection Act, 1970, and the associated policies and guidelines.

Summary of findings

The following information is relevant regarding the condition of the Site:

Soil

Groundwater

 There are four plumes of dissolved phase groundwater contamination beneath the site, three of which overlap in the northern section of the site (Area 2).

 Plumes 1, 2 and 4 do not pose an unacceptable risk for residents and commercial
workers for the various residential and commercial building scenarios that were modelled.

 Soil excavation and intrusive works.

 Groundwater abstraction and incidental contact.

 Property management activities.

The Groundwater Management Plan provides information on the requirements for ongoing monitoring of groundwater at the Site.

Suitability of the site – Zone C

On the basis of the work undertaken, the auditor is of the opinion that the Site (Zone C) is suitable for the intended purpose, that being a development of medium and/or density residential and/or commercial retail/office space as outlined in the site contamination management plan (Attachment B) comprising:

 Medium and/or high density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

2. All garden areas shall be backfilled with at least 1.0 metre of clean fill / topsoil.

3. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

4. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring.
5. If a basement car park is proposed, it can be expected to include a moisture/vapour barrier beneath the basement slab to prevent water ingress during the wet season when the water table is high.

Other related information:

The limitations outlined in Section 1.7 of this report should be referred to. DATED: 4 August 2014
SIGNED:

PETER NADEBAUM

Statement of Environmental Audit
Zone D

This Statement provides a summary of the findings of an Environmental Audit of Zone D of the property located at 38 McMinn Street, Darwin, Northern Territory in accordance with Section
47d of the Waste Management and Pollution Control Act (NT). The site is defined on Figure 1 in
Statement Attachment A.

Name of Auditor Dr Peter Nadebaum

Term of appointment of
Auditor

16 May 1990 to 25 September 2015

Date Audit requested 11 June 2010

Owners of the site Shell Company of Australia Limited

Person requesting a
Certificate

Peter Oxnam of Shell Company of Australia Limited (SCOA)

Planning Authority Development Consent Authority

Title Information Lot 5649, Town of Darwin

Area of the Site 18705m²

Zoning Central Business under the Northern Territory Planning Scheme

Address of the Site McMinn Street, Darwin, Northern Territory.

Current Occupier Unoccupied

Site Assessor URS Australia Pty Ltd (URS)

Audit Completion Date 4 August 2014

The audit has had regard to, amongst other things:

 The Waste Management and Pollution Control Act NT 1998.

 The National Environmental Protection Measure for Assessment of Site Contamination
1999 (NEPM, 1999).

 The NT Water Act 1992.

 Advice provided by the Northern Territory Environment Heritage & Arts Division, Department of Natural Resources Environment & the Arts (EHA/DNRETA).

 The general principles for undertaking audits, as outlined by Part IXD of the Victorian
Environment Protection Act, 1970, and the associated policies and guidelines.

Summary of findings

The following information is relevant regarding the condition of the Site:

Soil

Groundwater

 There are four plumes of dissolved phase groundwater contamination beneath the site, three of which overlap in the northern section of the site (Area 2).

 Plumes 1, 2 and 4 do not pose an unacceptable risk for residents and commercial
workers for the various residential and commercial building scenarios that were modelled.

 Soil excavation and intrusive works.

 Groundwater abstraction and incidental contact.

 Property management activities.

The Groundwater Management Plan provides information on the requirements for ongoing monitoring of groundwater at the Site.

Suitability of the site – Zone D

On the basis of the work undertaken, the auditor is of the opinion that the Site (Zone D) is suitable for the intended purpose, that being a development of medium and/or density residential and/or commercial retail/office space as outlined in the site contamination management plan (Attachment B) comprising:

 Medium and/or high density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

2. Medium or high density residential must be constructed above open ground level parking.

3. Larger scale commercial retail/office space may be constructed as slab on grade or above open ground level parking
4. Smaller scale commercial retail/office space must be constructed above open ground level parking
5. No Slab on grade for residential or small scale commercial retail/office

6. If a basement car park is proposed, it can be expected to include a moisture/vapour barrier beneath the basement slab to prevent water ingress during the wet season when the water table is high.

7. All garden areas must be backfilled with at least 1.0 metre of clean fill / topsoil

8. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

9. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring

Other related information:

The limitations outlined in Section 1.7 of this report should be referred to. DATED: 4 August 2014
SIGNED:

PETER NADEBAUM

Statement of Environmental Audit
Zone E

This Statement provides a summary of the findings of an Environmental Audit of Zone E of the property located at 38 McMinn Street, Darwin, Northern Territory in accordance with Section
47d of the Waste Management and Pollution Control Act (NT). The site is defined on Figure 1 in
Statement Attachment A.

Name of Auditor Dr Peter Nadebaum

Term of appointment of
Auditor

16 May 1990 to 25 September 2015

Date Audit requested 11 June 2010

Owners of the site Shell Company of Australia Limited

Person requesting a
Certificate

Peter Oxnam of Shell Company of Australia Limited (SCOA)

Planning Authority Development Consent Authority

Title Information Lot 5649, Town of Darwin

Area of the Site 4231 m²

Zoning Central Business under the Northern Territory Planning Scheme

Address of the Site McMinn Street, Darwin, Northern Territory.

Current Occupier Unoccupied

Site Assessor URS Australia Pty Ltd (URS)

Audit Completion Date 4 August 2014

The audit has had regard to, amongst other things:

 The Waste Management and Pollution Control Act NT 1998.

 The National Environmental Protection Measure for Assessment of Site Contamination
1999 (NEPM, 1999).

 The NT Water Act 1992.

 Advice provided by the Northern Territory Environment Heritage & Arts Division, Department of Natural Resources Environment & the Arts (EHA/DNRETA).

 The general principles for undertaking audits, as outlined by Part IXD of the Victorian
Environment Protection Act, 1970, and the associated policies and guidelines.

Summary of findings

The following information is relevant regarding the condition of the Site:

Soil

Groundwater

 There are four plumes of dissolved phase groundwater contamination beneath the site, three of which overlap in the northern section of the site (Area 2).

 Plumes 1, 2 and 4 do not pose an unacceptable risk for residents and commercial
workers for the various residential and commercial building scenarios that were modelled.

 Soil excavation and intrusive works.

 Groundwater abstraction and incidental contact.

 Property management activities.

The Groundwater Management Plan provides information on the requirements for ongoing monitoring of groundwater at the Site.

Suitability of the site – Zone E

On the basis of the work undertaken, the auditor is of the opinion that the Site (Zone E) is suitable for the intended purpose, that being open space parklands and landscaped gardens as
outlined in the site contamination management plan (Attachment B).

6. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

7. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring
8. In their letter dated 23 May 2014 (Appendix B), the NT EPA requested that “In relation to the adjacent lots, Barneson Street Road Reserve and Crown Land Lot
6663, that have residual groundwater impact, Shell make formal written notification
to the Department of Transport and the Department of Land, Planning and the Environment informing them of the status of the groundwater impact and the statement of environmental audit and associated conditions”.

Other related information:

The limitations outlined in Section 1.7 of this report should be referred to. DATED: 4 August 2014
SIGNED:

PETER NADEBAUM

Statement Attachment A

Site Development Plan and Surveyed
Plan of Site Boundaries

GHD | Report for Shell Company Australia - Environmental Audit Report, 22/15171/104595

A! MW113

A! MW112

A! MW121
A! MW111

ZONE D - MD / C-R
MW 122 MW 117 MEDIUM DENSITY
A! A! Residential & Commericial - no slab on grade or basement
ZONE E - OS MW 118 & Commercial (bulky goods) - no basement
OPEN SPACE A!
MW08 MW 120
A! MW 119 A! A!
A! A! A! A MW 110 A!
MW205 MW204 MW203 !A! MW 109 MW21
MW17 A!
4231m² A!
A!MW207 A! MW 116
A A! A! MW22
MW15
! MW07
MW206 MW201 A! A! MW09 A!
MW16
A! MAW20
!

A! A! MW06 A!
MW11

MW 114
18705m²
MW10 MW18
ZONE A - HD A! A! MW 105
HIGH DENSITY A!
Residential - no restriction

MW 115
A!
MW12
A!

A! MW04 M A! 5 MW19
W0
A!
23329m² A!
MW 102 MW13 MW 106
A! M A! A!
W03

ZONE C - MD MEDIUM DENSITY
MW 103 21668m² Residential - no restriction
M A! 1 A! A! MW14
W0

2231m²
A! MW 101
MW02
A!
MW 107
A!

MW 104
MWA! A!
23

MW 108
A! ZONE B - HD-R HIGH DENSITY
Residential - no basement

Legend

A! Monitoring wells included in the
SMP monitoring schedule
A! Monitoring wells not included in the
SMP monitoring schedule
Escarpment approximate location
Zoning Areas
HD HD-R MD MD/C-R OS
Former Fuel Lines
Former Infrastructure
W Water Services S Sewer Sevices P Power Services

0 10 20 30 40 50 m
Drawn: JD Approved: TS Date: MAY 2014
Job No: 42213921 File No: 42213921-045.mxd
Client

The Shell Company of Australia Pty
Project

MCMINN STREET FORMER SHELL TERMINAL
Title
SITE MANAGEMENT PLAN - DEVELOPMENT ZONES AND RESTRICTIONS

Figure: 1 Rev: A
A3

drw T:\Jobs\42213921\General figures\MXD

Residential & Commericial - no slab on grade or basement

drw T:\Jobs\42213921\General figures\MXD

Statement Attachment B

Site Contamination Management Plan (SMP)
– Current version as at 16/7/2014

GHD | Report for Shell Company Australia - Environmental Audit Report, 22/15171/104595

Site Contamination Management Plan

Site Contamination Management Plan - Former Shell
McMinn Terminal, Darwin

16/7/14

Prepared for
Shell Company of Australia Pty Ltd

8 Redfern Road Hawthorn East Victoria 3123

42213921

Project Manager:

Principal-In-Charge:

…………………………… Tim Smith
Senior Environmental
Geologist

…………………………… Andrew Piggin
Senior Principal Engineer

URS Australia Pty Ltd

Level 3, 93 Mitchell Street
Darwin, NT 0800
GPO Box 2005, Darwin NT 0801
Australia

T: 61 8 8980 2900
F: 61 8 8941 3920

Author:

…………………………… Tim Smith
Senior Environmental
Geologist

Reviewer:

…………………………… Gary Smith
Senior Principal Engineer

Date: Reference: Status:

16/7/14
42213921/SMP/02
F

Document delivery

URS Australia provides this document in either printed format, electronic format or both. URS Australia considers the printed version to be binding. The electronic format is provided for the client’s convenience and URS Australia requests that the client ensures the integrity of this electronic information is maintained. Storage of this electronic information should at a minimum comply with the requirements of the Electronic Transactions Act 2000 (Cth).

SUMMARY OF DEVELOPMENT ZONES AND DEFINITIONS ..................................v

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

1.1 General................................................................................................................ 1

1.2 Objectives ........................................................................................................... 2

1.3 Scope of Work .................................................................................................... 2

1.4 Development at the Site Allowable Under the Statement of
Environmental Audit .......................................................................................... 3

1.5 Notes on use of the SMP ................................................................................... 4

2 Background.............................................................................................................5

2.1 Site Details.......................................................................................................... 5

2.2 Site Description / History .................................................................................. 5

2.3 Development Restrictions Resulting from Soil and Groundwater
Impacts ............................................................................................................... 5

2.3.1 Residual Soil Impact Background..................................................................................5

2.3.2 Development Restriction Zones Resulting from Soil Impact ......................................6

2.3.3 Residual Groundwater Impact Background..................................................................7

2.3.4 Development Restriction Zones Resulting from Groundwater Impact ......................7

2.3.5 Free Product (light non-aqueous phase liquid – LNAPL) ............................................8

2.4 Regulatory Framework ...................................................................................... 8

2.4.1 Land Uses .........................................................................................................................9

2.4.2 Groundwater.....................................................................................................................9

2.4.3 Existing and Potential Future Land and Groundwater Uses .......................................9

3 Post-Remediation Environmental Management Plan .......................................11

3.1 Responsible Parties......................................................................................... 11

3.2 Key Stakeholders and Communications Plan............................................... 11

3.3 Future Soil Excavation and Intrusive Works ................................................. 11

3.3.1 Trigger Events for Soil ..................................................................................................12

3.4 Groundwater Abstraction and Incidental Contact ........................................ 13

3.4.1 Incidental Contact with Groundwater ..........................................................................13

3.4.2 Trigger Events for Groundwater ..................................................................................13

3.5 Groundwater Monitoring Plan ........................................................................ 14

3.5.1 Maintenance of Wells ....................................................................................................14

Table of Contents

3.5.2 Decommissioning of Wells ...........................................................................................15

4 Property Management ..........................................................................................17

4.1 Property Management Activities by Site Owner ........................................... 17

4.1.1 Restricted Use of Groundwater ....................................................................................17

5 Reporting...............................................................................................................19

5.1 Review and Cessation of Site Management Plan ......................................... 19

5.2 Future Site Audit .............................................................................................. 19

6 Frequently Asked Questions ...............................................................................21

7 References ..............................................................................................................1

8 Limitations ..............................................................................................................3

8.1 Definitions .......................................................................................................... 3

8.2 Conclusions and Limitations ............................................................................ 3

Tables

Table 1-1 Allowable Development and Restrictions ......................................................................... 3

Table 2-1 Site Identification............................................................................................................... 5

Table 2-2 Relevant Legislation.......................................................................................................... 8

Table 3-1 Key Stakeholders ............................................................................................................ 11

Appendices

Appendix A Figures

Appendix B Groundwater Quality Management Plan

Appendix C Outline for Development of a Construction and Environmental Management Plan

Appendix D Additional CEMP considerations

Abbreviation Description
AAPA Aboriginal Areas Protection Authority
ANZECC Australian and New Zealand Environment and Conservation Council
BFV Barmah Forest virus
CBD Central Business District
CEMP Construction Environmental Management Plan
COPC Chemical of Potential Concern CUTEP Clean-up to the Extent Practicable dB(A) Decibel – A-weighted
DCC Darwin City Council
DLPE Department of Lands, Planning and the Environment (NT) E&SCP Erosion and Sedimentation Control Plan
EMP Environmental Management Plan

EPBC Act Environment Protection and Biodiversity Conservation Act 1999 (Commonwealth)
ERP Emergency Response Plan
ESA Environmental Site Assessment
ESD Ecologically Sustainable Development
GHG Greenhouse gasses
GME Groundwater Monitoring Event
GQMP Groundwater Quality Management Plan
HASP Health and Safety Plan
HD High Density
HD-R High Density with restrictions
HERA Human Health and Environmental Risk Assessment km Kilometre
KMP Key Management Plan
KUNV Kunjin virus
LNAPL Light Non-Aqueous Phase Liquid m metres
MD Medium Density
MD-R Medium Density with restrictions NES National Environmental Significance MVEV Murray Valley encephalitis virus
NT Northern Territory
NTG Northern Territory Government

NT EPA Northern Territory Environmental Protection Authority (Formerly NRETAS – Department of Natural Resources, Environment, The Arts and Sport)
ODS Ozone depleting gasses
OHS Occupational Health and Safety
OS Open Space
PWC PowerWater Corporation
RRV Ross River virus
SEPP State Environment Protection Policy (Victoria) Shell Shell Company of Australia Limited

Abbreviation Description
SMP Site Management Plan
TDS Total Dissolved Solids
TRH Total Residual Hydrocarbon
URS URS Australia Pty Ltd UXO Unexploded Ordnance Vic EPA Victorian EPA
WMPC Act Waste Management and Pollution Control Act (NT)

SUMMARY OF DEVELOPMENT ZONES AND DEFINITIONS

For the purpose of this Site Management Plan the following general definitions of site use are made:

• High Density Residential is considered to consist of multi-storey high rise residential units with minimal access to garden and soil.
• Medium Density Residential is considered to consist of multi-storey and/or semi-detached
residential units or apartments with minimal access to garden and soil.
• Commercial Retail/Office Space is considered to consist of

— larger scale commercial retail (such as a supermarket, bulky goods retail or other open plan commercial retail space) or larger open plan office space, or
— smaller scale commercial retail (such as newsagent, restaurants, convenience store etc.) or smaller office space/consulting rooms

• Accessible gardens and soil are considered to be areas where residents may regularly dig in site derived soils for the purpose of maintaining a garden or to grow produce for consumption.

The following table defines currently allowable land uses across the five (5) development zones. Restrictions are based on residual contamination remaining beneath portions of the site.

It is noted that some development types that are listed as non-allowable may be allowed where additional controls such as sub-slab moisture/vapour barriers or further excavation, removal and assessment of residual contamination beneath building footprints are implemented. In this instance further consultation with an appropriately qualified and experienced environmental consultant and an environmental auditor would be required.

Development Zones
Allowable Development under
Environmental Audit Conditions
Non-allowable Development under
Environmental Audit Conditions

Zone A
HD – high density High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed above a basement car park
— constructed as slab on grade
— constructed above open ground level parking
Residual contamination within Zone A
does not preclude
— Deep excavations
— Swimming pool

No accessible gardens or soil

Zone B
HD-R – high density with some restrictions High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed above open ground level parking
Residual contamination within Zone A
does not preclude
• Deep excavations
• Swimming pool

No accessible gardens or soil
No slab on grade*
No basement car park*

*slab on grade and basement car park may be allowable with consideration of additional engineering controls (e.g. moisture/ vapour barrier beneath slab)

Zone C
MD – medium density Medium and/or High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking No accessible gardens or soil
No restrictions to the type of medium density residential apartments or commercial retail/office space

*however basement car parking has not been considered a likely use without moisture/vapour barriers beneath the basement slab to prevent likely

— constructed above a basement car park
Residual contamination within Zone C
does not preclude
• Deep excavations
• Swimming pool water ingress from seasonal waterlogging of soils and shallow groundwater

Zone D
MD-R – medium density with some restrictions
Medium and/or High density residential apartments with any of the following scenarios:
— constructed above open ground level parking
Larger scale commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking
Smaller scale commercial retail/office space with any of the following scenarios:
— constructed above open ground level parking
Residual contamination within Zone D
does not preclude
• Deep excavations
• Swimming pool

No accessible gardens or soil
No medium density residential constructed as slab on grade**
No small scale commercial retail/office space constructed as slab on grade**
No basement car park**

**Basement car park and medium density residential constructed as slab on grade may be allowable with consideration of additional engineering controls (e.g. moisture/ vapour barrier beneath slab, sub slab venting)

Zone E
OS – open space

• Open space parklands and landscaped gardens
• Deep excavations
No accessible gardens or soil
No slab on grade habitable structures
No swimming pool with enclosed change room/toilets or filter room

1
1Introduction

1.1 General

URS Australia Pty Ltd (URS) was engaged by the Shell Company of Australia Limited (Shell) to prepare this Site Contamination Management Plan (SMP) for the former Shell McMinn Street Terminal (the Site), located at 38 McMinn Street, Darwin, Northern Territory (Figure 1).

The site was formerly used as a petroleum terminal until 2006 which resulted in hydrocarbon contamination in soil and groundwater beneath the site. Clean-up has since occurred however some residual impacts remain at the site which require ongoing management

The Site is currently under a Statutory Environmental Audit under the Northern Territory Waste Management and Pollution Control Act (WMPC Act). The environmental audit of the site has been undertaken by Dr Peter Nadebaum of GHD Pty Ltd in accordance with the WMPC Act.

It is understood that the Northern Territory Environmental Protection Authority (NT EPA) intends to issue a Pollution Abatement Notice (PAN) once the audit is complete to ensure management of residual contamination. The environmental audit of the site consists of five (5) individual audit statements that correspond to the different risk profiles for specific areas of the site (Zones A to E – Figure 2).

This document provides guidance to assist developers and occupiers to manage residual contamination. At the date of this SMP, there is no current PAN issued for the Site.

A Clean-up to the Extent Practicable (CUTEP) submission has been prepared for the site to demonstrate to the Auditor and NT EPA that site clean-up to the extent practicable has been achieved. Shell is committed to developing and implementing strategies and associated activities to guide management of post-active remediation soil and groundwater impacts at, and in the vicinity of, the Site through the generation and implementation of this SMP. Following site divestment, the new owner will be responsible for maintaining the conditions of the SMP for as long as residual hydrocarbon impacts at the Site restrict beneficial uses of land and/or groundwater. This SMP includes actions for:

• Site restoration from historical soil and groundwater impacts;
• Mitigation of risks to, and protection of, land and groundwater beneficial uses;
• Minimisation of human health and environmental risk;
• Monitor groundwater impacts to ensure that they remain acceptable;
• Management of post-remediation hydrocarbon impacted areas;
• Decommissioning of monitoring wells at the end of service life or when no longer necessary for monitoring;
• Stakeholder and community relations; and
• Post-remediation Site operations and maintenance activities, as required.

The main stakeholders in the project are Shell (site owner), URS (assessor), GHD (auditor), future site owners, the NT EPA (environmental regulator), future site developers, the Northern Territory Department of Lands, Planning and the Environment (DLPE), the Northern Territory Development Consent Authority (DCA) and Darwin City Council (DCC).

Following completion of Site audit-related investigations including completion of a Validation Report (detailing post-remediation Site conditions), a Human Health and Environmental Risk Assessment (HERA), a Site Contamination Management Plan (this report), a Clean-Up to the Extent Practicable (CUTEP) report, and a Statement of Environmental Audit for each of the five (5) development

restriction zones (submitted by the Auditor to NT EPA for consideration), the anticipated end use for specific areas of the site includes high and medium density residential development, commercial bulky goods development, with parks and open space for the remainder of the site.

1.2 Objectives

The objectives of this SMP are to:

1. Outline site management practices which will limit the potential adverse impacts on human health, the environment or the amenity of the site resulting from residual contamination;
2. Outline ongoing groundwater monitoring requirements;
3. Detail triggers for stakeholder engagement related to site contamination;
4. Outline trigger events for additional assessment of future groundwater beneficial use impacts;
5. Detail actions that should be followed in the event that and environmental trigger occurs;
6. Provide an ongoing schedule for assessing when Site restoration is complete.

It is assumed that the NT EPA, DCA, DLPE and Darwin City Council will prescribe allowable land use activities within residual impact areas, in accordance with long term land use zoning and planning.

1.3 Scope of Work

To achieve SMP objectives, the following plans and activities are required and addressed herein:

• Groundwater Quality Management Plan (GQMP – Appendix B) including requirements for ongoing periodic monitoring of groundwater impacts, focussed on sentinel monitoring wells located along the northern boundary of the Site and monitoring wells used as inputs for modelling in the HERA (detailed in Appendix B);
• Construction and Environmental Management Plan (CEMP – Appendix C) including requirements
for management of impacted soil and groundwater during construction, implementation of health and safety measures to reduce potential contact with impacted soil and groundwater, implementation of conditions and specifications contained within the audit statement.
• Establishment of trigger event criteria that may instigate additional investigation, monitoring or
assessment of impacts to future soil and groundwater beneficial uses;
• Detail of actions and/or communication should trigger events occur;
• Detail restrictions on use post development of the site; and
• Communication of the development conditions stipulated for the site in co-operation with NT EPA, DCA, DLPE and DCC to alert parties of impact areas on-site.

Roles and responsibilities for implementing the SMP, including the GQMP and CEMP, will be retained by the site owner.

1.4 Development at the Site Allowable Under the Statement of
Environmental Audit

This SMP has been developed based on the conditions in the five (5) Statements of Environmental
Audit and the assumed development scenarios1 for the site being high and medium density

1 It is noted that alternative development scenarios may be proposed but will require further assessment by an accredited environmental auditor.

1 Introduction

residential/commercial apartment development, commercial bulky goods development, with parks and open space for the remainder of the site.

For clarity the development zones (Zones A to E) supporting these development scenarios are included in Figure 2 and summarised in Table 1-1 below.

Table 1-1 Allowable Development and Restrictions

Development Zones Allowable Development under
Environmental Audit Conditions Non-allowable Development under
Environmental Audit Conditions

Zone A
HD – high density
High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed above a basement car park
— constructed as slab on grade
— constructed above open ground level parking
Residual contamination within Zone A
does not preclude
— Deep excavations
— Swimming pool

No accessible gardens or soil

No accessible gardens or soil
No slab on grade*
No basement car park*

*slab on grade and basement car park may be allowable with consideration of additional engineering controls (e.g. moisture/ vapour barrier beneath slab)

Zone C
MD – medium density Medium and/or High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking
— constructed above a basement car park
Residual contamination within Zone C
does not preclude
• Deep excavations
• Swimming pool

No accessible gardens or soil
No restrictions to the type of medium density residential apartments or commercial retail/office space

*however basement car parking has not been considered a likely use without moisture/vapour barriers beneath the basement slab to prevent likely water ingress from seasonal waterlogging of soils and shallow groundwater

Zone D
MD-R – medium density with some restrictions Medium and/or High density residential apartments with any of the following scenarios:
— constructed above open ground level parking
Larger scale commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking No accessible gardens or soil
No medium density residential constructed as slab on grade**
No small scale commercial retail/office space constructed as slab on grade**
No basement car park**

Development Zones Allowable Development under
Environmental Audit Conditions Non-allowable Development under
Environmental Audit Conditions
Smaller scale commercial retail/office
space with any of the following scenarios:
— constructed above open ground level parking
Residual contamination within Zone D
does not preclude
• Deep excavations
• Swimming pool

Zone E
OS – open space
• Open space parklands and landscaped gardens
• Deep excavations No accessible gardens or soil
No slab on grade habitable structures
No swimming pool with enclosed change room/toilets or filter room

1.5 Notes on use of the SMP
• The SMP is not intended to provide detailed information on site environmental conditions at the time of completion of the audit. The site owner, regulatory authorities, development consent authority, environmental consultants, developers of the site, the body corporate or other persons who need to rely on such information, should refer to the Statement of Environmental Audit prepared by Dr Peter Nadebaum of GHD for the site and any referenced environmental reports.
• It should be noted that site environmental conditions will change over time, residual hydrocarbons
in soil and groundwater will degrade and there may be new sources of contamination. The reports related to the site represent the environmental conditions at the time of completion of the audit.
• This SMP is intended to address the management of residual site soil and groundwater impacts,
however compliance with this document does not relieve parties from their responsibility to comply with all occupational health and safety and environmental requirements in accordance with statutory Acts or regulations, by-laws, rules and other special requirements of relevant Authorities

A discussion of relevant environmental legislation is presented as Section 2.4.

To aid persons with a non-technical background in environmental assessments and environmental audits a Frequently Asked Questions section has been prepared in Section 6. This section aims to state in plain language some of the potential issues that may arise during and following development of a former petroleum storage and handling facility and some of the ways in which these issues should be addressed when they are encountered.

2
2Background

2.1 Site Details

Site Identification details and background information are presented in Table 2-1 below. Site locality and surrounding land use is shown on Figure 1, with the development zones shown on Figure 2.

Table 2-1 Site Identification

Site Identification Former Shell McMinn Street Terminal, Darwin
Site Location: 38 McMinn Street, Darwin, Northern Territory
Site Area: 70,200 m2
Property Zoning: Central Business Darwin (CB)

2.2 Site Description / History

The site commenced operations as a petroleum terminal circa 1937 (Coffey Environments, ESA,
2006) where hydrocarbon products were handled and stored. The site ceased operation in October
2005 and, excluding the site office, fire water mains and off-site product delivery line, was decommissioned with petroleum related infrastructure removed in June 2006.

2.3 Development Restrictions Resulting from Soil and Groundwater
Impacts

There are five (5) development zones across the site (Zones A to E see Figure 2), each development zone has been evaluated separately given the different risk profiles associated with each development zone. Assessment in this way makes it clear to future users of the site what development options would be appropriate for particular parcels of land across of the Site, as part of managing residual impacts.

2.3.1 Residual Soil Impact Background

Soil remediation was conducted during 2011. Soil was excavated, treated on-site by land farming, and reinstated. In areas where bedrock was encountered, excavation of contamination was not practicable. Post-remediation conditions are as follows:

• The western, northern, eastern and central portions of the site retain residual soil hydrocarbon impacts, primarily as residual non-volatile diesel/fuel oil hydrocarbons within the underlying bedrock.
• An additional control measure was implemented with the covering of reinstated remediated areas
with at least 1 m of non-impacted soil to prevent direct dermal contact. The 1 m of non-impacted soil cover is an important control measure at the site and should be maintained at all times. Where the cover is disturbed or removed it should be replaced with similar material to maintain this direct contact barrier.
• The southern corner of the site between the site boundary and the open storm water drain mostly
consists of exposed bedrock and has no hydrocarbon impacts.

Soil vapour monitoring within Zones A, B and E of the site found little or no volatile hydrocarbons that were found to pose a human health or environmental risk as detailed in the HERA (URS 2013b).

2.3.2 Development Restriction Zones Resulting from Soil Impact

There are two areas of the site that have development restrictions as a result of residual soil impact as detailed below. It is important to note that these areas are suitable for the stipulated site use where the specified controls/restrictions are applied. It is also noted that alternative building/development types may be proposed within these zones, however, an environmental auditor would need to be engaged and additional engineering controls may be required to prevent ingress of contaminated vapours or groundwater.

Zone B – HD-R

Allowable uses include:

High density residential and/or commercial retail/office space constructed above open ground level car park

As a result of shallow soil impacts that may pose an unacceptable vapour intrusion risk to slab on grade high density residential buildings or commercial retail/office space.

• Restrictions within Zone B include

— No accessible gardens or soil
— No slab on grade*
— No basement car park*

*slab on grade and basement car park may be allowable with consideration of additional engineering controls (e.g. moisture/ vapour barrier beneath slab)

Zone D – MD-R

Allowable uses include:

Medium and/or high density residential constructed above open ground level car park and/or
Smaller scale commercial retail/office space constructed above open ground level car park and/or
Larger scale commercial retail (bulky goods) or office space constructed slab on grade

As a result of soil impact at depths of greater than 1 m that may pose an unacceptable vapour intrusion risk to slab on grade medium and high density residential buildings or smaller scale commercial retail/office space.

• Restrictions within Zone D include

— No accessible gardens or soil
— No medium or high density residential constructed as slab on grade**
— No small scale commercial retail/office space constructed as slab on grade**
— No basement car park**

2 Background

2.3.3 Residual Groundwater Impact Background

There are four distinct residual groundwater impact areas identifiable beneath the site, three of which overlap in the northern and north eastern portion of the site. The identified impact areas are as follows:

1. Kerosene/jet fuel/diesel and lubrication oil type impact centred on Zone B (Figure 2) located within elevated western area of the site (Zone A). There are no unacceptable vapour risks to high density residential development resulting from this groundwater plume as detailed in the HERA (URS
2013b).

2. Kerosene/jet fuel/diesel type impact centred on monitoring wells located to the north east of the site centre within Zone D. There are no unacceptable vapour risks to medium density residential buildings resulting from this groundwater plume as detailed in the HERA (URS 2013b).

3. Predominantly avgas/unleaded/leaded type impact centred on monitoring wells located in the northern corner of the site (Zone E). The HERA (URS 2013b) indicated that as a result of potential vapour intrusion risk to habitable enclosed structures, this area is currently not suitable for slab-on- ground residential or commercial use, but is suitable for public open space use.

4. Kerosene/jet fuel/diesel type impact located within Zone E in the northern corner of the site. There are no unacceptable vapour risks resulting from this groundwater plume as detailed in the HERA (URS 2013b).

These four residual impact areas are discussed in more detail in the updated HERA (URS 2013b).

Overall for site impacted groundwater, consolidation of groundwater data from 2006 to 2013 has demonstrated that the dissolved phase hydrocarbon impact is generally decreasing with time, spatially stable, and mostly delineated on-site – noting that there is some seasonal variability in observed COPC concentrations related to the timing and magnitude of wet season rainfall events and seasonal total rainfall. It is noted that impacted groundwater located along the northern site boundary in Zone E and extending off-site is delineated by off-site wells. Former product lines to the BP, Mobil, Caltex and Shell Harvey Street sites were located in the vicinity of this residual impact area.

2.3.4 Development Restriction Zones Resulting from Groundwater Impact There is one area of the site that has development restrictions as a result of residual groundwater impact detailed below. It is important to note that this area is suitable for the stipulated site use where
the specified controls/restrictions are applied

Zone E – OS

Allowable uses include

Open space parklands and landscaped gardens

As a result of groundwater impacts that may pose an unacceptable vapour intrusion risk within habitable structures.

• Restrictions within Zone E include

— No accessible gardens or soil
— No slab on grade habitable structures
— No swimming pool with enclosed change room/toilets or filter room

It is also noted that alternative building/development types may be proposed within this zone, however, an environmental auditor would need to be engaged and additional engineering controls may be required to prevent ingress of contaminated vapours or groundwater.

2.3.5 Free Product (light non-aqueous phase liquid – LNAPL)

Free product (as opposed to hydrocarbons dissolved in the groundwater) has not been observed at the site since 2006, with the exception of one well (MW07 located close to the western boundary of Zone E) during one monitoring event in 2013. Three centimetres of product was detected floating on the groundwater in well MW07. This is inferred to be associated with very low groundwater levels allowing the release of localised pockets of hydrocarbon contamination trapped in the fractured rock beneath the site and does not indicate that any significant pockets of residual hydrocarbons remain. This well is located in a contamination source area and monitoring results indicate that the extent is localised. Construction of buildings within Zone E is not permitted

2.4 Regulatory Framework

This SMP has been prepared to be consistent with the provisions and land and groundwater protection obligations of relevant Northern Territory and Victorian legislation. Where legislation exists in the Northern Territory that legislation takes precedence over Victorian legislation.

Table 2-2 below summarises the key relevant legislation under which this SMP has been prepared:

Table 2-2 Relevant Legislation

Legislation Key Considerations

Northern Territory Waste Management and Pollution Control Act (2013) • Primary statutory law of the environment
• Provides for the protection of the environment through encouragement of effective waste management and pollution prevention and control practices and for related purposes
• Defines overall principles of environment management
• Defines responsibility of stakeholders for environmental management
• Water quality objectives for the site defined by Water Quality Objectives for the Darwin Harbour Region – Background Document (2010)
Northern Territory Water Act (2011) • provides for the investigation, allocation, use, control, protection, management and administration of water resources, and for related purposes
Northern Territory Environmental
Offences and Penalties Act (2011) • establishes penalties for certain offences under prescribed Acts, and for related purposes
National Environment Protection Council (Northern Territory) Act (2004) • provides for the establishment of a National Environment
Protection Council, and for related purposes
• enacts the National Environment Protection (Assessment of Site Contamination) Measure 1999, amended 2013 – establishes and identifies the beneficial uses for the land to be protected
National Environment Protection (Assessment of Site Contamination) Measure 1999, amended 2013 • Establishes and Identifies the beneficial uses for the land to be protected
Given the site is currently under assessment by an Independent Environmental Auditor accredited by the Victorian EPA and recognised by the NT EPA the following Victorian legislation has also been considered as guidance.

2 Background

Legislation Key Considerations
SEPP (Prevention and Management of Contaminated Land) • Establishes and Identifies the beneficial uses for the land to be protected
• Provides a statutory framework for protecting people and the environment from the effects of polluted land.
• Sets measures to prevent and manage contamination and aims to maintain and improve the condition of land to protect current and future uses from contamination.
SEPP (Waters of Victoria) • Establishes and Identifies the beneficial uses for water in Victoria to be protected
SEPP (Groundwaters of Victoria) • Establishes and Identifies specific beneficial uses for groundwater in Victoria to be protected
• Provides direction to stakeholders regarding the management of polluted groundwater zones with the implementation of a groundwater quality restricted use zone – no mechanism to enact this in the NT.
• Section 18 was considered at this site: “where non-aqueous phase liquid (NAPL) is present in the aquifer, it must be removed unless the authority is satisfied that there is no unacceptable risk posed to any beneficial use by the NAPL.” The authority in this instance is the NT EPA.

EPA Publication 840 (The Clean Up and Management of Polluted Groundwater)
• Provides further direction to stakeholders regarding the clean-up and management of polluted groundwater zones, and defines Clean Up to the Extent Practicable (CUTEP).

2.4.1 Land Uses

The site is situated within the central business area of Darwin. The site is surrounded by a mixture of commercial, residential and waterfront and maritime industrial properties including Frances Bay Mooring and Fishermen’s Wharf. The planned end use for the site is designated areas of high and medium density residential development, commercial bulk goods storage and related uses, with parks and open space for the remainder of the site. Surrounding land uses are summarised in Table 2-5.

The site is suitable for high and medium density residential use, commercial use and public open space within the conditions detailed in the Statement of Environmental Audit (prepared by Dr Peter Nadebaum of GHD).

The site is not suitable for unrestricted low density residential use.

2.4.2 Groundwater

The groundwater beneath the site is inherently suitable for a range of beneficial uses based on freshwater quality, however it is considered that extraction for beneficial use is unlikely based on poor aquifer yield and ready availability of reticulated supply. Additionally as a result of historical contamination groundwater beneath the site is not suitable for extraction for beneficial uses including drinking water, irrigation and primary contact recreational waters. These beneficial uses are not
considered relevant to the Darwin CBD by the NT EPA (see Section 2.4.3).

2.4.3 Existing and Potential Future Land and Groundwater Uses

The proposed redevelopment of the site is for high and medium density residential with some commercial use and designated open space, in accordance with the current zoning.

Previous discussions and correspondence by the Auditor with the NT EPA have indicated that the groundwater beneficial uses of agricultural / irrigation, primary contact recreation, potable and industrial uses are not relevant at sites within the Darwin CBD.

For the purpose of assessing the appropriate screening level guidelines and undertaking the HERA, some beneficial uses were not considered on the basis of the low-yielding aquifer, no identified abstraction of groundwater for beneficial uses within 1 km radium of the site, readily available reticulated domestic supply, surrounding land uses, and proposed development at the site. Potential groundwater beneficial uses in the vicinity of the site are considered to be limited to the protection of marine ecosystems, located approximately 300 m down-gradient of the site.

3
3 Post-Remediation Environmental Management Plan

The measures to be undertaken to manage the Site during post-remediation conditions have been developed to ensure environmental, social and financial factors are considered and incorporated into SMP activities.

3.1 Responsible Parties

The implementation of this SMP following on-site remediation and related risk assessment activities is the overall responsibility of the property owner. Day-to-day implementation of SMP activities may be delegated to a Consultant/Contractor.

The party responsible for residual impacts lingering from the previous use of the terminal is the Shell
Company of Australia Pty Ltd (current property owner).

Compliance with overall regulatory requirements as identified herein is the responsibility of the NT EPA, the NT Development Consent Authority, the site owner/developer/development contractors and the body corporate assigned at the completion of development.

3.2 Key Stakeholders and Communications Plan

The following table lists the key stakeholders for the project.

Table 3-1 Key Stakeholders

Stakeholder Who

Current Site Owner
Shell Australia Pty Ltd

Future Site Owner
Unknown (likely a local or regional land developer)

Environmental Auditor
Dr Peter Nadebaum

Remediation and Environmental Consultant
URS Australia Pty Ltd

Environmental Regulator
Northern Territory Environmental Protection Authority
(NT EPA)

Planning Department Development Consent Authority division of Northern Territory Department of Lands, Planning and the Environment
Local Council Darwin City Council
Traditional Owners Larrakeyah Aboriginal People
Down Gradient Landowner (neighbouring property to north) Crown Land – Northern Territory Government

The site owner will notify stakeholders when significant activities occur at the Site that may influence surrounding property owners, the overall community, or regulatory agencies. Examples of environmental activities or events that may trigger a communications event are site flooding during deluge rainfall events, or generation of nuisance odours during site construction.

3.3 Future Soil Excavation and Intrusive Works

Historically impacted soils in the middle of the site were remediated to the extent practicable (to the underlying rock) in 2011, with additional impacted soil disposed off-site in 2012. Areas of residual soil impact are characterised in the Environmental Validation Report (URS 2013a). The HERA (URS
2013b) considered the risks to on-site and off-site intrusive workers as a result of residual soil and

groundwater impacts and concluded that it was low and acceptable when working above bedrock level.

The owner of the site is responsible for implementation of management processes and procedures resulting from residual soil and groundwater impacts at the site during any future redevelopment. An outline for the development of a Construction and Environmental Management Plan (CEMP) is included in Appendix C.

3.3.1 Trigger Events for Soil

Trigger events described below are indicators of a potential change in the soil risk profile for the Site. If a contingency event is triggered, remedial or administrative actions will be required in accordance with the SMP procedures.

The following information has been provided to assist site personnel in taking appropriate occupational health and safety (OHS) precautions when working on the site. This document is intended as guidance information only and does not replace the requirement for preparation of a site-specific HSE or OHS plan specific to the maintenance or construction work undertaken. All works must be completed under the requirements of the NT Work Health and Safety (National Uniform Legislation) Act (2011), Work Health and Safety (National Uniform Legislation) Regulations (2012) and associated Work Health Court’s rulings.

Any work in confined spaces requires specialist training and procedures and falls outside the scope of these recommendations. Appropriate checks on air quality should be undertaken prior to commencement of any confined space works. This information relates to the management of site contamination issues only.

Change of Land Use

If a change of land use to a more sensitive use is proposed, the SMP will need to be reviewed to take account of potential new risks to land beneficial uses or receptors.

Odorous Material

The risk assessment undertaken for the site concluded that the risks to an intrusive worker undertaking excavation works in contaminated soil at this site are low and acceptable. To provide additional protection to the finding of the risk assessment, it is recommended that contact with odorous, potentially contaminated soil be minimised by appropriate use of Personal Protective Equipment (PPE) and Personal Hygiene.

Odours from excavated soil should not be detected beyond the boundary of the premises. If odours may be detected beyond the site boundary, management measures should be implemented to prevent this occurring.

Where unexpected odorous material is encountered during excavation for construction of a slab-on- ground or basement type dwelling or habitable structure, it is recommended that works be temporarily suspended and the situation assessed by an appropriately qualified and experienced environmental consultant. Odorous material should be stockpiled on plastic sheeting or in a skip bin and should be protected from rainfall and potential run-off.

Where unexpected odorous material is encountered during excavation for a non-habitable structure, service trenches, swimming pools or landscaping in the upper 1 m of soil, it is recommended that this material be assessed and disposed off-site in accordance with the requirements of the receiving site, where the site is not a licenced facility it is recommended that the material be assessed by an appropriately qualified and experienced environmental consultant to ensure no potential harm to human health or the environment. Where this material is encountered greater than 1 m below the site finished surface it may be reintroduced to the excavation with not less than 1 m of clean fill cover.

Dusts

High winds and excavation activities can result in airborne hazards. The potential for dust generation during any site excavation activities should be assessed. Should dust be produced during invasive operations, dust should be suppressed with a fine spray of water or equivalent methods.

3.4 Groundwater Abstraction and Incidental Contact

Previous discussions and correspondence by the Auditor with the NT EPA have indicated that the beneficial uses of agricultural/irrigation, primary contact recreation, potable and industrial uses are not considered relevant at sites within the Darwin CBD. Given the low yield and presence of a reticulated water supply it is not considered likely that groundwater supply bores will be approved or installed on or in the vicinity of the site. Groundwater may be sampled periodically for monitoring purposes by an environmental consultant.

The Groundwater Quality Management Plan (GQMP) is included in Appendix B and includes detail of monitoring procedures and trigger events. The GQMP is a stand-alone document and should be consulted for management of any potential groundwater impact issue.

3.4.1 Incidental Contact with Groundwater

Incidental contact could occur at the site during or following wet season rainfall events where groundwater may seep to the surface. This is most likely to occur at the lower elevations of the escarpment or other low lying areas of the site. Areas of seepage are unlikely to be in areas where the groundwater is impacted. During activities where incidental contact with groundwater may occur, the recommended minimum level of clothing and equipment in the HSEP should be applied.

3.4.2 Trigger Events for Groundwater

The trigger events described below are indicators of a potential change in the risk profile for the Site. If a contingency event is triggered, remedial or administrative actions will be required in accordance with the actions detailed below.

Change of Land Use

If a change of land use to a more sensitive use is proposed, the SMP will need be reviewed to take account of potential new risks to land use or groundwater beneficial uses.

Installation of Groundwater Supply Abstraction Bores

Groundwater beneath the site is impacted by residual petroleum hydrocarbons and should not be abstracted or used.

Change in Groundwater Conditions

If monitoring indicates that the on-site dissolved phase groundwater impact is no longer stable or decreasing, the NT EPA and the Department of Land, Planning and Environment should be notified, and potentially an environmental auditor to discuss implementation of potential corrective measures. Notification and discussion with the above mentioned parties is of particular importance where off-site conditions are affected.

3.5 Groundwater Monitoring Plan

Details of further groundwater monitoring at selected indicator wells to assess on-going site conditions are included in the GQMP in Appendix B.

Based on groundwater monitoring from 2006 - 2013, the conclusions of the HERA report, and CUTEP submission for the site, further groundwater monitoring for site characterisation is not considered necessary. This conclusion is based on the following:

• No potential primary sources of impact have been present at the site since 2005.
• Extensive areas of impacted soil (secondary source) were excavated, remediated by land farming
(65-85% reduction in impact) and reinstated at the site, with a 1 m clean soil cover.
• Groundwater impact at the site is well characterised and spatially stable and remains mostly within the site boundary.
• Groundwater impact does not pose a risk to on-site or off-site intrusive workers.
• Residual groundwater impact vapour risk to slab-on-grade commercial and residential development has been identified in one area of the site as identified herein and such development is not permitted in this area of the site.
• Groundwater impact extending along the north boundary is spatially stable, well characterised and
presents no vapour intrusion risks to slab-on-grade development or intrusive workers.
• Natural attenuation of dissolved phase hydrocarbons is active at the site and as such it is expected that concentrations will continue to reduce with time.
• The down gradient site is owned by the Northern Territory Government and at present is zoned
‘PM – proposed main road’ (currently under development application for that purpose).
• Previous discussions and correspondence by the Auditor with the NT EPA have indicated that the beneficial uses of agricultural/irrigation, primary contact recreation, potable and industrial uses are not considered relevant at sites within the Darwin CBD. Given the low yield and presence of a reticulated water supply it is not considered likely that groundwater supply bores will be approved or installed on or in the vicinity of the site.

3.5.1 Maintenance of Wells

A reduced network of monitoring wells will be required at the completion of the site audit. The site owner should maintain a minimal network of monitoring wells as recommended in the GQMP (Appendix B) in an operational state until the NT EPA supports cessation of monitoring, at which time it is considered remaining monitoring wells should be decommissioned. Monitoring wells not considered required for ongoing monitoring should be decommissioned as soon as is feasible with the approval of the NT EPA.

3.5.2 Decommissioning of Wells

Well abandonment/decommissioning will be conducted by the site owner at the completion of environmental assessment work in accordance with the requirements of the NT Water Act (2011), and in consultation with the NT EPA.

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4
4Property Management

4.1 Property Management Activities by Site Owner

The site owner will be responsible for maintenance of the site such that it does not pose a nuisance or hazard to surrounding properties and users. Activities during construction will be managed by a CEMP, the guidelines for which are included in Appendix C. Management activities at the site may include the following:

• Periodic monitoring of groundwater at the site boundary;
• Erosion and runoff control measures to ensure the site does not generate nuisance or potentially contaminated sediment during the wet season;

Additional management activities unrelated to site contamination may also be required and are not detailed in this SMP.

4.1.1 Restricted Use of Groundwater

Previous discussions and correspondence by the Auditor with the NT EPA have indicated that the beneficial uses of agricultural/irrigation, primary contact recreation, potable and industrial uses are not relevant at sites within the Darwin CBD. Given the low yield and presence of a reticulated water supply it is not considered likely that groundwater supply bores will be approved or installed on or in the vicinity of the site.

The Water Resources Division of the Department of Land Resource Management administers the regulatory functions of the NT Water Act. This includes permits and licences for Groundwater extraction and water bore drilling. The section also assesses compliance under the NT Water Act in relation to Groundwater Extraction Licences, Bore Construction Permits and the investigation of breaches under the NT Water Act.

Information relating to bore construction permits and licenced drillers is available at this website:

http://lrm.nt.gov.au/water/permits?_sm_au_=iVVPk57SWZpSH8M5#.UjeWYNJmhcY .

Darwin CBD and the site does not fall within a water control district which means there is no requirement to apply for a bore licence with the Water Resources Division of the Department of Land Resource Management.

However if a proponent/driller wishes to install a commercial or domestic potable supply bore it is a requirement to notify the Environmental Health Branch of the Department of Health. The use of such bores for potable supply is controlled under the NT Public and Environmental Health Act 2011 and Public Health Regulations.

Information about supply of potable water is included in an information sheet available at this website including guidance for separation distances from potential contamination sources such as septic systems, etc. and advice to “only extract groundwater from a place where subsurface contaminants are unlikely. Avoid sites with known contaminants, including heavy industrial and intensive agriculture areas.”

http://www.health.nt.gov.au/library/scripts/objectifyMedia.aspx?file=pdf/42/67.pdf&siteID=1&str_title=G
uidelines%20for%20Private%20Water%20Supplies.pdf

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5.1 Review and Cessation of Site Management Plan

This SMP will be reviewed by the site owner every four years, or during change in ownership of the property, or prior to the commencement of construction works at the site, or at the time and in the event of a significant trigger exceedance, such as a new environmental threat to groundwater beneficial uses.

In the event that the SMP needs to be modified, this should be completed in accordance with the procedures contained in this SMP, and in consultation with the NT EPA.

The SMP will cease to be necessary at the site when 1) the owner receives permission from NT EPA to cease site monitoring activities, or 2) practicable groundwater beneficial uses have been restored. Consultation with the NT EPA will be necessary for the cessation of site management.

5.2 Future Site Audit

If deemed necessary by NT EPA at the time of cessation of site management, the owner will retain an accredited independent environmental Auditor to perform a closeout VicEPA 53V audit of the site. The responsibility for appointing and retaining a site auditor will be retained by the site owner and be determined at the time of the audit requirement imposed by NT EPA.

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6
6Frequently Asked Questions

What does this document mean to a property owner wishing to plant a tree, install a landscape irrigation system, or install a pool; or to a tradesperson coming to site to perform works? The intent of this section is to direct potential enquiries to the appropriate section of this Site Management Plan or provide a contact for further information.

This site was formerly a petroleum terminal facility and portions of the site are contaminated. In the first instance you should engage an appropriately qualified and experienced environmental consultant to review the audit report and attached assessment reports for the purpose of understanding the potential contamination issues in the relevant area, where excavations greater than 1 m are proposed.

What should I do if I wish to excavate on the site?

Before you plan any excavation you should engage an appropriately qualified and experienced environmental consultant as recommended above. If, following review of the appropriate site reports, excavation is considered appropriate then you should consider the following during planning.

You should first obtain dial-before-you-dig plans (available on-line at http://1100.com.au/ or call 1100). You should also consult as-built plans available from the body corporate or NT Planning Authority. You should also consider engaging a service location contractor to confirm the presence of service lines on the property.

How deep can I excavate?

As recommended above before you plan any excavation you should engage an appropriately qualified and experienced environmental consultant. If, following review of the appropriate site reports, excavation is considered appropriate then, as a rule-of-thumb across the site, it is recommended that you dig no deeper than approximately 0.75 m.

Across much of the site, bedrock is close to the surface (less than 0.5 m) particularly the elevated areas of the site around Barneson and McMinn Streets. In the central area of the site, it is possible to excavate deeper, however the clean soil cover may be disturbed. Where this clean soil cover is disturbed a minimum 1.0 m of clean soil cover will need to be reinstated at the completion of works. During excavation soils from the upper 1 m should be kept separate from deeper excavated soil and rock to prevent mixing with potentially contaminated deeper soils and rock. Excavated soils from beneath the 1m cover cannot be placed for reuse on the surface.

What if I want to build an in-ground swimming pool?

It is possible to build a swimming pool at the site within Zones A, B, C and D, however given the depth of excavation required it is recommended that you be aware that odorous and potentially contaminated soil and groundwater may be encountered during excavation works. It is recommended that a construction and environmental management plan (CEMP) be prepared to limit direct contact with potentially contaminated soil, accumulation of hydrocarbon vapours in the open excavation, address confined space entry requirements and other health and safety considerations during excavation (outside the scope of this document) as well as disposal of excavated soil (at a higher cost than clean fill).

It is recommended that an appropriately qualified and experienced environmental consultant be engaged prior to works to aid in preparation of a CEMP and assess whether excavated soil requires

disposal to an appropriately licenced facility. It is also recommended that Section 3.3 of this SMP be consulted for specific trigger events during excavation works.

It is also possible that bedrock may be encountered and require extensive work with a rock breaker and large excavator (particularly in the upper area of the site where rock is hard), it is recommended that an appropriately qualified and experienced environmental consultant be engaged to consider specific potential contamination considerations in hard rock in addition to the CEMP measures detailed above.

What if I notice odours when I dig in the garden?

It is not anticipated that persistent odours will be encountered while digging in the top 1 m of soils across the site.

Prior to areas of the site being used for accessible gardens, an appropriately qualified and experienced environmental consultant should be engaged and the area specific information in the SMP should be reviewed.

If persistent odours are encountered in areas of the site where they are not anticipated be present (i.e. within 1 m of the site surface and within Zones A and C) an appropriately qualified and experienced environmental consultant should be engaged to assess the soil. An environmental auditor may also need to be consulted.

Notice to residents:

Most odours if encountered are likely to be transient in nature and not generally noticeable a short distance from the excavation. If persistent odours are noticed while digging in gardens (i.e. excavated soils are still odorous when sitting undisturbed approximately 15 or 20 minutes after excavation), simply place the soil back in the hole, wash your hands, and contact the body corporate.

Can I excavate or blast bed rock?

Hydrocarbon contamination is flammable and residual contamination may be ignited by blasting or heat/sparks generated by excavation in rock. This potential risk must be considered and managed during works.

Yes you can excavate bedrock however if excavation of bedrock is undertaken for a dwelling or habitable structure it may alter the exposure scenarios modelled in the risk assessment. It is recommended you engage an appropriately qualified and experienced environmental consultant to assess the proposed design against the site Human Health and Environmental Risk Assessment (HERA). It is also possible that excavated bedrock may be contaminated, and may require disposal to an appropriately licenced facility.

Additional health and safety measures unrelated to potential residual soil impacts will need to be applied at the site for blasting and excavation works.

What if I notice groundwater seepage at the surface?

It is expected that in some areas of the site groundwater may come to the surface as seepage or a spring during and immediately following the wet season. This is most likely to occur towards the base of the escarpment and in the lowest elevations of the site. This is normal and is not expected to pose a potential risk to human health or the environment.

6 Frequently Asked Questions

If odorous seepage is encountered it is recommended that you notify the site owner/developer/development contractors or body corporate.

What if I notice sheen on groundwater seepage at the surface or in an excavation?

In most instances the sheen that is noticed is likely to be the result of iron deposition (red/orange colouration), a silvery film/sheen at the surface (commonly associated with iron reducing bacteria) or natural oils where decomposing organic matter is present. This can sometimes be mistaken for hydrocarbon sheen.

If you notice a “rainbow” coloured sheen on surface water, it is recommended that you avoid incidental contact and inform the site owner/developer/development contractors or the body corporate.

What happens if deep excavations are proposed?

If deep excavations are proposed or undertaken it may alter the exposure scenarios modelled in the risk assessment. It is recommended that an appropriately qualified and experienced environmental consultant and an environmental auditor be engaged to consider the proposed design against the assumptions in the site specific Human Health and Environmental Risk Assessment (HERA).

It is also possible that excavated bedrock may be contaminated and that ingress of potentially contaminated groundwater will occur into excavations. It is recommended that an appropriately qualified and experienced environmental consultant be engaged prior to and during deep excavation works to assess potentially contaminated soil and groundwater for on-site re-use or off-site disposal.

Additionally, it is recommended that a construction and environmental management plan (CEMP) be prepared to limit direct contact with potentially contaminated soil/rock, accumulation of hydrocarbon vapours in the open excavation, address confined space entry requirements and other health and safety considerations during excavation (outside the scope of this document).

I’ve noticed a monitoring well, what is it for and what should I do?

There are a number of monitoring bores on or around the site that you may notice as a small round lid approximately 20 cm across. Please do not tamper with or attempt to open monitoring bores. These are important to enable monitoring of the groundwater beneath the site to inform the NT EPA if there are any changes to site conditions. Residual groundwater impacts are naturally attenuating at the site. If you notice damage to a monitoring well please inform the site owner/developer/development
contractors or the body corporate.

Are there any risks of exposure to contamination when I take my children to play in the open space areas of the site?

Soil contamination is present in some areas of the site however it occurs at a depth of greater than
1 m in the open space area of the site or within bedrock in the upper portion of the site. Therefore the potential for direct contact with residual site contamination under normal play uses is negligible.

As detailed in the Human and Environmental Risk Assessment for the site, the risk to human health posed by soil and groundwater contamination in the open spaces of the site is low and acceptable.

Groundwater contamination is present beneath some areas of the site and is largely inaccessible. There are some instances where groundwater may intersect the surface of the site as seeps. If this does occur refer to “What if I notice groundwater seepage at the surface?” above.

Can I grow vegetables in the garden?

It is possible to grow vegetables in gardens at the site however as a precaution it is not recommended that vegetables are grown in gardens consisting of soil derived from the site.

This recommendation is not based on potentially adverse human health risks but is a precaution based on historical use of the site as a petroleum terminal.

It is noted that much of the site consists of outcropping rock but where soil is present the upper 1 m consists of site-won clean fill which is intended to act as a buffer to prevent direct contact with potentially contaminated soils at greater than 1 m depth. This soil consists of orange brown sandy clayey silt with 5-10% rocky inclusions, contains limited organic matter and would likely require significant work to support a productive vegetable garden.

It is recommended that if vegetables are to be grown that they be grown in raised beds of soil imported to site more suitable to gardening for fresh produce.

7
7References

ANZECC/ARMCANZ, (2000). Australian Water Quality Guidelines for the Protection of Aquatic
Ecosystems.

Australian and New Zealand Environmental and Conservative Council, (2004). Australian Water
Quality Guidelines for Fresh and Marine Waters.

Northern Territory Environmental Offences and Penalties Act (2011)

Northern Territory National Environment Protection Council (Northern Territory) Act (2004) Northern Territory Waste Management and Pollution Control Act (2013)
Northern Territory Water Act (2011)

Victorian EPA Publication 840 (The Clean Up and Management of Polluted Groundwater) Victorian SEPP (Groundwaters of Victoria)
Victorian SEPP (Prevention and Management of Contaminated Land) Victorian SEPP (Waters of Victoria)
URS Australia Pty Ltd, 2013a. Final Draft Environmental Validation Report, Former Shell Terminal, McMinn Street Darwin, Northern Territory. Published May 2013.

URS Australia Pty Ltd, 2013b. Final Draft Human Health and Environmental Risk Assessment, Former
Shell Terminal, McMinn Street Darwin, Northern Territory. Published May 2013.

URS Australia Pty Ltd, 2013c. Draft Clean-Up to the Extent Practicable Report, Former Shell Terminal, McMinn Street Darwin, Northern Territory. Published June 2013.

Water Quality Objectives for the Darwin Harbour Region – Background Document (2010)

http://lrm.nt.gov.au/

data/assets/pdf_file/0005/16565/WQGO_for_DH_Feb_2010_final.pdf?_s

m_au_=iVVHNnnRFBhvSvRM .

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8
8Limitations

8.1 Definitions
Report means this document and all appendices, tables, figures and other attachments to this Report. Pre-Existing Reports means those documents which are referred to in this Report and/or attached as appendices to this Report.

8.2 Conclusions and Limitations

This SMP report was prepared to provide support for the Auditor’s (Dr Peter Nadebaum of GHD) CUTEP submission to the Northern Territory Environment Protection Authority (NT EPA). The document is an active document for the management of residual risks at the site and assigns responsibilities for those management actions to various stakeholders.

This conclusion and all information in this Report is given strictly in accordance with and subject to the following limitations and recommendations:

a) URS Pty Ltd (URS) has prepared this report in accordance with the usual care and thoroughness of the consulting profession for the use of Shell Company of Australia Pty Ltd.
b) Except as required by law, no third party may use or rely on, this Report unless otherwise agreed by URS in writing. Where such agreement is provided, URS will provide a letter of reliance to the agreed third party in the form required by URS.
c) This Report should be read in full and no excerpts are to be taken as representative of the findings.
No responsibility is accepted by URS for use of any part of this Report in any other context.
d) This Report was prepared between 7 June 2013 and 30 May 2014. Report and conclusion are based solely on the information and findings contained in this Report and/or any Pre-Existing Reports, and on the conditions encountered and information reviewed at the time of preparation of the Report and/or any Pre-Existing Reports. URS accepts no responsibility for any events arising from any changes in site conditions or in the information reviewed that have occurred after this period of time.
e) This Report should be read in conjunction with any Pre-Existing Reports and is subject to all limitations and recommendations included in any Pre-Existing Reports.
f) This conclusion is based solely on the scope of work agreed between URS and Shell and described in Section 1.3 Scope of Works of this Report.
g) To the extent permitted by law, URS expressly disclaims and excludes liability for any loss, damage, cost or expenses suffered by any third party relating to or resulting from the use of, or reliance on, any information contained in this Report. URS does not admit that any action, liability or claim may exist or be available to any third party.
h) URS does not represent that this Report is suitable for use by any third party in deciding whether to enter a transaction in relation to the Property or to put the Property to a particular use.
i) Except as specifically stated in this section, URS does not authorise the use of this Report by any third party.
j) It is the responsibility of third parties to independently make inquiries or seek advice in relation to their particular requirements and proposed use of the Property.
k) URS has been retained to prepare this Report as an independent contractor of Shell and not as an agent of Shell. Shell is not to be taken as making under any circumstances whatsoever or on any account whatsoever, any statement, representation, warranty or endorsement as to the adequacy or otherwise of the Report.

8 Limitations

l) The assessments and/or investigations carried out for the purposes of the Report have been undertaken, and the Report has been prepared, in accordance with current professional practice and by reference to applicable environmental regulatory authority and industry standards, guidelines and assessment criteria in existence at the date of this Report and any Pre-Existing Reports.
m) Where this Report indicates that information has been provided to URS, or prepared by third
parties, URS has made no independent verification of this information except as expressly stated in the Report.
n) URS has considered and/or tested for only those chemicals specifically referred to in this Report.
URS makes no statement or representation as to the existence (or otherwise) of any other chemicals.
o) Assessments and/or investigations undertaken in respect of this Report are constrained by the particular site conditions, such as the location of buildings, infrastructure, services and vegetation. As a result, not all relevant site features and contamination may have been identified in this Report.
p) Unless expressly stated in this Report, no intrusive work has been undertaken within the vicinity of any existing fuel infrastructure. As a result, environmental conditions within these areas have not been investigated.
q) Unless otherwise expressly stated in the Report, no investigations have been undertaken into and/or assessments made of any off-site conditions, or whether any adjoining sites may have been impacted by contamination or other conditions originating from this site.
r) Surface and sub-surface conditions can vary across a particular site and cannot be exhaustively defined by the assessments and/or investigations described in this Report. The results expressed in this Report represent conditions at the specific locations of investigation and/or assessment only and are not necessarily representative of conditions across the whole site.
s) Except as otherwise expressly stated in this Report, URS makes no warranty or representation as to the presence or otherwise of asbestos and/or asbestos containing materials (“ACM”) on the site. Even if asbestos was tested for and those test results did not reveal the presence of asbestos at specific points of sampling, if fill has been imported on to the site at any time, or if any buildings constructed prior to 1970 have been demolished on the site or materials from such buildings disposed of on the site, the site may contain asbestos or ACM.
t) Except as otherwise expressly stated is this report, URS makes no warranty, statement or representation of any kind concerning the suitability of the site for any purpose or the permissibility of any use, development or re-development of the site.
u) URS offers no opinion as to whether the current site use has any or all planning, environmental, accredited site auditor or other approvals required, is operating in accordance with any such approvals, the likelihood of obtaining any such approvals, or the conditions and obligations which such approvals may impose, which may include the requirement for additional environmental works. The ongoing use of the site and/or use of the site for any different purpose may also require the owner/user to manage and/or remediate site conditions, such as contamination and other conditions, including but not limited to conditions referred to in this Report.
v) URS makes no determination or recommendation regarding a decision to provide or not to provide financing with respect to the site.
w) Any estimates of potential costs which have been provided are presented as estimates only as at the date of the Report. Any cost estimates that have been provided may therefore vary from actual costs at the time of expenditure.

8 Limitations

Nothing in this section or in this Report in any way affects, limits or qualifies URS's obligations and liabilities, or Shell's rights and benefits under the agreement entitled “Global Framework Arrangement for the Procurement of Services” No. RET/10/0314/GLES between Shell International Petroleum Company Limited and URS Europe Limited (as amended, varied, supplemented, novated or replaced).

A
Appendix A Figures

A! MW113

A! MW112

A! MW121
A! MW111

A! A! MW06 A!
MW11

MW 114
18705m²
MW10 MW18
ZONE A - HD A! A! MW 105
HIGH DENSITY A!
Residential - no restriction

MW 115
A!
MW12
A!

A! MW04 M A! 5 MW19
W0
A!
23329m² A!
MW 102 MW13 MW 106
A! M A! A!
W03

ZONE C - MD MEDIUM DENSITY
MW 103 21668m² Residential - no restriction
M A! 1 A! A! MW14
W0

2231m²
A! MW 101
MW02
A!
MW 107
A!

MW 104
MWA! A!
23

MW 108
A! ZONE B - HD-R HIGH DENSITY
Residential - no basement

Legend

0 10 20 30 40 50 m
Drawn: JD Approved: TS Date: MAY 2014
Job No: 42213921 File No: 42213921-045.mxd
Client

The Shell Company of Australia Pty
Project

MCMINN STREET FORMER SHELL TERMINAL
Title
SITE MANAGEMENT PLAN - DEVELOPMENT ZONES AND RESTRICTIONS

Figure: 1 Rev: A
A3

drw T:\Jobs\42213921\General figures\MXD

Residential & Commericial - no slab on grade or basement

B
Appendix B Groundwater Quality Management Plan

This Groundwater Quality Management Plan (GQMP) applies to the former Shell McMinn Terminal site, Lot 5649 Town of Darwin from plan(s) S 87/280, located at 38 McMinn St, Darwin.

This GQMP has been developed to comply with the Northern Territory Water Act 1992. This GQMP has been developed to manage contaminated groundwater related to former petroleum storage and delivery activities at the site.

The monitoring and/or management plan ensures there is a notification process to the Department of Lands, Planning and the Environment and the NT EPA of any changes in monitoring data that indicate the contamination is migrating further outside the site boundaries, or any other changes that may indicate an increase in the potential for environmental harm.

The GQMP comprises three main components. The first component is a groundwater monitoring program which provides information relating to the groundwater system (hydrogeology and impacts to quality). The second component involves periodic assessment and review of the GQMP procedures using the results of the groundwater monitoring program. The third component is the utilisation of the GQMP as a decision making tool. The GQMP will be reviewed periodically and adjusted to reflect changing groundwater conditions, as may be required. The structure of the GQMP is a continuous cycle of monitoring, assessment and review to allow for logical and informed management. This process is illustrated in Figure B-1.

Figure Appendix B-1 GQMP Structure Flow Chart

Appendix B - Groundwater Quality Management Plan

B.1 GQMP Objective

The objective of this GQMP is to outline the management of groundwater contamination at the site in order to protect he beneficial uses of land and groundwater affected by site contamination.

The URS report titled “Clean-up to the Extent Practicable (CUTEP) Report, Shell McMinn Terminal”
2013c has concluded that the groundwater is polluted with respect to some beneficial uses of land and groundwater, requiring this GQMP to provide a means by which the identified groundwater contamination can be suitably managed.

B.2 Administration of the Plan

The responsibility for ensuring administration of the GQMP will remain with the site owner. The responsibility for ensuring compliance with the GQMP is with the Northern Territory Environment Protection Authority (NT EPA).

B.3 Review of GQMP

The GQMP is expected to cover a minimum period of 4 years. The GQMP has been designed to cover the transition from environmental investigation and remediation, through site development and construction phase, to post-development monitoring and eventual cessation of monitoring works.

A groundwater monitoring report will be prepared annually including recommendations regarding the cessation of monitoring. It is recommended that a review of the GQMP be undertaken annually by an appropriately experienced environmental consultant in consultation with an environmental auditor and discussed with the NT EPA in order to transition to cessation of monitoring as early as is supported by the data.

An extension of monitoring may be required if the contaminant trigger levels in Section B.9.3 are exceeded.

B.4 Beneficial Use of the Aquifer Beneath the Site

Previous discussions and correspondence by the Auditor with the NT EPA have indicated that the beneficial groundwater uses of agricultural / irrigation, primary contact recreation, potable and industrial uses are not relevant at sites within the Darwin CBD.

The remaining beneficial use is protection of marine aquatic ecosystems (located approximately
300 m east and down gradient of the site).

B.5 Supported Site Development Options

The site is zoned Central Business (CB). The primary purpose of zone CB is to provide for a diversity of activities including administrative, judicial, professional, office, entertainment, cultural, residential and retail and other business activities with a commitment to the separation of incompatible activities.

The anticipated end use for the site includes high and medium density residential development, commercial bulky goods development, with parks and open space for the remainder of the site. These development options are broadly supported at the site with certain development options being restricted in specific zones, as defined in Table B-1, Figure 2, and the Site Management Plan (URS
2013d) which is based on the findings of the URS Human Health and Environmental Risk Assessment
(HERA) (URS 2013b).

Table-B-1 Allowable Development and Restrictions

Development Zones Allowable Development under
Environmental Audit Conditions Non-allowable Development under
Environmental Audit Conditions

No accessible gardens or soil

No accessible gardens or soil
No slab on grade*
No basement car park*

*slab on grade and basement car park may be allowable with consideration of additional engineering controls (e.g. moisture/ vapour barrier beneath slab)

Zone C
MD – medium density
Medium and/or High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking
— constructed above a basement car park
Residual contamination within Zone C
does not preclude
• Deep excavations
• Swimming pool

No accessible gardens or soil
No restrictions to the type of medium density residential apartments or commercial retail/office space

Zone D
MD-R – medium density with some restrictions Medium and/or High density residential apartments with any of the following scenarios:
— constructed above open ground level parking
Larger scale commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking
Smaller scale commercial retail/office space with any of the following scenarios:
— constructed above open ground level parking
Residual contamination within Zone D
does not preclude

No accessible gardens or soil
No medium density residential constructed as slab on grade**
No small scale commercial retail/office space constructed as slab on grade**
No basement car park**

Appendix B - Groundwater Quality Management Plan

Development Zones Allowable Development under
Environmental Audit Conditions Non-allowable Development under
Environmental Audit Conditions
• Deep excavations
• Swimming pool

B.6 Restrictions

The groundwater beneath the site, as a result of contamination, is not suitable for extraction for beneficial uses including drinking water, irrigation and primary contact recreational waters.

Beneficial use of the land in the northern corner of the site, as defined in SMP Figure 2, is restricted to recreational open space as a result of residual groundwater impacts beneath that area, and low elevations. Beneficial uses across other areas of the site are not affected by remaining groundwater impacts, however other restrictions have been placed on development as a result of soil contamination, as defined in SMP Figure 2.

B.7 Site Inspections

B.7.1 Purpose and Scope

In order to maintain the integrity of the groundwater monitoring infrastructure at the site routine inspections are required. Identification and reporting of any failure of infrastructure to the site owner will allow for scheduling of maintenance and repair.

Areas of potential seepage at the base of escarpment features and in low lying areas to the north eastern portion of the site should be inspected for sheens or staining.

Areas required to be regularly inspected are listed in Table Appendix B-1 Routine inspections of groundwater monitoring infrastructure for maintenance below. It is important to note that should any other item be observed as requiring maintenance, whether related to the groundwater monitoring system or not, it should be reported to the site owner/developer/development contractors or the body corporate, who may then delegate maintenance requirements.

Table Appendix B-2 Routine inspections of groundwater monitoring infrastructure for maintenance

Inspection site Inspection process

Bore hole covers and locks Check for damage or loss

Bore holes and piezometers Check for damage or blockages

Access routes Check for damage or access issues

B.7.2 Frequency

General inspections of groundwater infrastructure should be formally carried out annually at the same time as groundwater sampling occurs. However, an informal inspection may be carried out at any time appropriate personnel are in the immediate vicinity.

B.7.3 Records

A record of the condition of monitoring infrastructure is to be included in the field sampling records completed annually at the time of groundwater monitoring event. The field sampling form should include but is not limited to; the condition of the well, a photograph of the wells, requirement for maintenance action, date and time, and person carrying out the inspection. The same information should be recorded during informal inspections.

B.7.4 Personnel

Inspections carried out at the time of groundwater monitoring events should be undertaken by appropriately experienced and qualified groundwater sampling personnel. Informal inspections may be carried out by a non-qualified person. If any damage is identified, it is recommended the site owner/developer/development contractors or the body corporate engage a licenced driller or qualified environmental scientist to investigate the issue prior to organising maintenance depending on the nature of the damage.

B.8 Groundwater Monitoring

B.8.1 Purpose and Scope

Previous assessments of groundwater quality have found petroleum hydrocarbon contamination in some areas of the site. The conclusions of the Human Health and Environmental Risk assessment completed at the site are reliant upon groundwater monitoring data from these assessments. The use of groundwater quality and water level elevation data collected as a part of the groundwater monitoring program are used to ascertain whether groundwater conditions at the site are stable and if the concentrations of contamination are continuing to decrease. If changes in groundwater conditions are detected further investigation and management contingency options can be commenced.

B.8.2 Groundwater Monitoring Locations

Groundwater monitoring locations to be included in the monitoring program include:

• MW07 (source location for HERA modelling – highest concentrations on-site)
• MW207 (down gradient of MW07)
• MW203 (down gradient of MW07 – at site boundary)
• MW204 (down gradient of MW07 – at site boundary)
• MW205 (down gradient of MW07 – at site boundary)
• MW117 (off-site and down gradient of MW07)
• MW118 (off-site and down gradient of MW07)
• MW119 (off-site and down gradient of MW07)
• MW122 (off-site and down gradient of MW07)
• MW11 (source location for HERA modelling)

Appendix B - Groundwater Quality Management Plan

• MW02 (source location for HERA modelling)
• MW03 (source location for HERA modelling)
• Surface seepage – monitor for seepage of groundwater at the site surface in the vicinity of MW203, MW204 and MW205 (outcropping bedrock down gradient of MW07)

Monitoring locations are illustrated in SMP Figure 1.

Additionally any seepage of groundwater at the surface noted down gradient of MW07 (in the vicinity of MW203, MW204 and MW205) should be sampled and included in the monitoring program.

It is important to ensure all nominated bores are sampled to ensure the current groundwater conditions are adequately assessed. Damage or blockage to any of the nominated groundwater monitoring locations must be immediately reported to the site owner/developer/development contractors or the body corporate to ensure the integrity of the groundwater monitoring network is maintained.

Should damage or blockage prevent access or monitoring and sampling of a well, the damage or blockage should be assessed and if possible repaired to allow monitoring at the same time as the rest of the monitoring network. If repair is not possible the site owner/developer/development contractors or the body corporate and the NT EPA should be notified. An appropriately qualified and experienced environmental consultant and potentially an environmental auditor may need to be engaged to consider if a replacement bore may need to be installed. Sampling of all designated monitoring wells at the site must take place as close to the end of the wet season as possible.

B.8.3 Groundwater Sampling Methodology

Groundwater sampling at the site has been undertaken using low flow sampling techniques. It is recommended that this be continued for future monitoring events.

It is recommended that in the absence of specific Northern Territory guidance groundwater sampling be undertaken consistent with methodology detailed in Standards Australia (1998), AS/NZS 5667
Water quality—sampling or other state regulatory guidance such as South Australian EPA (2007), Regulatory monitoring and testing, Groundwater sampling or Victorian EPA (2000), Groundwater sampling guidelines, Publication Number 669.

Other passive sampling techniques may be proposed for the site and considered by the NT EPA. Bailing is not considered an appropriate sampling methodology for this site.
General groundwater sampling and monitoring procedures and methods should be based on the Australian Guidelines for Water Quality Monitoring and Reporting (PIMC-NRMMC, 2000), whilst sampling procedures relating to contaminated groundwater are outlined in the Victorian EPA (Publication 441 and 669) Groundwater Sampling Guidelines (2000) . All sampling procedures should comply with the Australian and New Zealand Water Quality Standard; AS/NZS 5667 (1998). Gauging must be undertaken during sampling events, prior to any groundwater extraction for purposes
including purging or sampling.

B.8.4 Measurable Light Non-Aqueous Phase Liquid (LNAPL)

In the event of LNAPL (a layer of phase separated liquid) being observed in a well, field observations should be made of the apparent thickness, colour (including a photograph) and incidental odour. If the

apparent thickness of the LNAPL is greater than 2 mm a sample of the phase separated liquid should be obtained along with a sample of the groundwater beneath the LNAPL layer.

If the trigger events for LNAPL detailed in Section B.9.3 are encountered the site owner/developer/development contractors or the body corporate and the NT EPA should be notified as soon as practicable. Exceedance of trigger events may require further works outside the monitoring program set out within the GQMP.

B.8.5 Groundwater Data

It is proposed that the groundwater data be reviewed annually by an environmental consultant in the context of the historical site data to determine impacted groundwater trends. Following the data trend review, the monitoring event should be reported as an annual report to the NT EPA with the objective of ceasing groundwater monitoring at the earliest time that is supported by data trends and the NT EPA.

B.9 Water Quality Investigation Levels

Trigger levels and water quality guidelines should be based on the Australian and New Zealand Conservation Council Guidelines for Fresh and Marine Water Quality (ANZECC, 2000) or any updated version of this document. It is noted that the Darwin Harbour Water Quality Objectives (DHWQO,
2010) are the locally applicable guideline, however the guidance for toxicants is based on the ANZECC guideline values. The information bulletin for the clean-up and management of polluted groundwater from the Victorian EPA (Publication 840) provides guidance on how to apply the guidelines and determine when clean-up has been achieved.

Due to the limited approved potential beneficial uses of the on-site groundwater, ANZECC water quality guidelines will be used. The objective of this GQMP is to specify an appropriate monitoring program that provides assurance that groundwater contamination plume is steady or decreasing and therefore not impacting beneficial uses.

B.9.1 Groundwater Levels

Groundwater level (elevation) data will also be used to determine stability of groundwater flow direction and the presence or absence of LNAPL.

B.9.2 Groundwater Quality

Groundwater quality parameters to be collected are detailed below and may be used to infer the effects of various land uses, hydrogeochemical processes, and natural physicochemical attenuation processes. Future management of the aquifer beneath the site may be based on quantification and trends evident within the hydrogeochemistry of the groundwater system.

Electrical Conductivity (EC) Surrogate for salinity and can be used to characterise potential beneficial uses
of the groundwater
pH Acidity/Alkalinity can limit or support many geochemical interactions in the groundwater environment. Can also affect structures that are in direct contact
with groundwater
Redox Potential (Eh) Oxidative potential of the groundwater can be used as a measure of capacity for
biodegradation of hydrocarbons and a qualitative measure of plume extent.
Dissolved Oxygen (DO) Concentrations of oxygen in groundwater can be used as a measure of capacity for biodegradation of hydrocarbons and a qualitative measure of plume extent.

Appendix B - Groundwater Quality Management Plan

Temperature Temperature controls the oxygen carrying capacity of groundwater. Hydrocarbon utilising bacteria are also more active in warm groundwater
environments.
Contaminants of Potential
Concern (COPC) Total Residual Hydrocarbons (TRH) C6-C40,
Benzene, Toluene, Ethylbenzene and Total Xylenes (BTEX), Lead, Methane, Ferrous/Ferric Iron, Nitrate/Nitrite, Sulphate/Sulphite
The laboratory selected for sample analysis should be NATA accredited and hold ISO 9100 certification. The laboratory should be within 24 hours travel of the site to allow for timely analysis of samples. Recommendations regarding the collection, transport and documentation of samples should be sought and followed from the laboratory and comply with the sampling guideline requirements as per the sampling guidelines listed in Section B9.6.

B.9.3 Trigger Levels and Contingency Actions

The following site-specific trigger levels are proposed:

• Appearance of a measurable thickness (>2 mm) of LNAPL (Light Non-Aqueous Phase Liquid or phase separated hydrocarbons) in a monitoring well that did not previously contain LNAPL.
• Greater than one order of magnitude increase in concentration of a dissolved phase COPC in
groundwater over the baseline trend.
• Trend of increasing LNAPL thickness over two consecutive monitoring rounds in a well that already contains LNAPL.
• Greater than 1 order of magnitude increase in concentration of boundary sentinel wells compared
to historical seasonal fluctuations.
• Any potential development or use of the land immediately adjacent to the site down gradient.
Further monitoring should be considered depending on the type and timing of any potential development.

If trigger levels are exceeded, further action will be required. It is considered that an environmental auditor may need to be engaged. The actions to be undertaken will be determined at the time on consultation between the site owner, an appropriately qualified and experienced environmental consultant, an environmental auditor, the NT EPA, and the Development Consent Authority but may include:

• Assessment of the significance of the exceedances and whether it could give rise to adverse effects, and determination of whether further follow up is required.

Further follow up could include all or some of the following:

• Re-sampling of existing bores or sampling on a more intense frequency in order to assess trends in greater detail
• Installation and monitoring of additional bores
• Installation of a groundwater control drainage system
• Localised impacted groundwater pumping including treatment system if required
• Installation of a cut off-wall if required

B.9.4 Monitoring Frequency

Groundwater Monitoring Events (GMEs) will be undertaken annually at the end of the wet season
(March/April). The end of the wet season is considered the most appropriate time to monitor as this is

the most likely period for contaminated groundwater to be most accessible at the surface via surface seeps or infiltration into open pits during any excavation work

The frequency of sampling and desired outcomes of the Groundwater Monitoring Program will be revised annually (June) with the NT EPA, an appropriately qualified and experienced environmental consultant and an environmental auditor following completion and submission of the annual monitoring event.

Groundwater monitoring events

The occurrence of a groundwater monitoring event must occur at the end of the wet season, in such a way as to be representative of wet season extremes and to allow assessment of groundwater seepage at the surface. The groundwater monitoring event should also occur as close as possible to the same time each year to allow for suitable comparison. It is suggested that this be based on the wet season rainfall pattern rather than a strict calendar date.

Groundwater monitoring duration

The initial duration of the groundwater monitoring program is anticipated to take place over approximately 4 years following completion of remediation works (GME conducted March 2013). The groundwater monitoring program will be reviewed annually. Ongoing monitoring may be discontinued in consultation with the NT EPA and an environmental auditor after the initial monitoring phase should results show 1) no new wells containing LNAPL, 2) dissolved phase further decreasing in concentrations, 3) no new COPC, and 4) results below assessment guideline thresholds. Discontinuation of monitoring will be subject to approval of the NT EPA.

Monitoring Schedule

Samples from monitoring bores and surface seeps should be submitted to a National Association of
Testing Authorities (NATA) accredited laboratory for the following contaminants of potential concern:

• Benzene, Toluene, Ethylbenzene and total Xylenes (BTEX)
• Total residual hydrocarbons C6-C40 (TRH C6-C40)
• Dissolved lead

B.9.5 Site Records and Reporting

Records relating to the groundwater monitoring program will consist of four parts;

1. Field data sheets;
2. Raw laboratory data and field data;
3. Groundwater monitoring program factual reports including interpretation of the groundwater data;
and
4. Recommendations regarding (but not limited to) expansion, reduction or cessation of the monitoring program.

Field data sheets

Notes taken in the field during a groundwater monitoring event will use a standard set of forms to record the following field parameters pH, TDS, EC, Redox and DO as well as depth to groundwater, presence/absence of LNAPL, odours, sheen, turbidity of the groundwater, volume of water removed

Appendix B - Groundwater Quality Management Plan

during sampling, rate of recovery within the well, weather details and any other field notes. The field sheets will be retained as an original copy of the data, will be kept as hard and electronic copies, and will be included with annual monitoring reports to NT EPA. All field notes should be taken using waterproof ink (in the event of rainfall during field work note-taking).

Raw laboratory data and field data

Laboratory analytical results are provided in electronic format and will be provided with the annual report. Raw laboratory data will be validated for accuracy and precision and compared to field observations for anomalous or unexpected data. Groundwater parameters collected during a groundwater monitoring event will be entered into a database containing all available groundwater data.

Groundwater monitoring report

A groundwater monitoring report will be prepared after each annual monitoring event. The groundwater monitoring report will present data factually and discuss the results in the context of historical data trends and any guideline trigger value exceedances including recording of actions taken.

The results of the on-going monitoring will be reported by the site owner to NT EPA on an annual basis. Monitoring reports will be used as a basis for decisions regarding cessation of the groundwater monitoring program.

Recommendations for site improvements

In addition to the annual groundwater monitoring report, recommendations for site improvements based on any contingency actions will be prepared based on the available database for the site and the results of any contingency actions. Recommendations are to include discussion of the monitoring program and a proposed time period to cessation of monitoring.

B.9.6 Personnel

Groundwater monitoring must be carried out by a suitable qualified environmental professional.

B.10 Disposal of Waste

B.10.1 Water

Where waste water is generated during groundwater monitoring it will be disposed by an appropriately licenced liquid waste contractor.

Where waste water is generated as a result of rainfall events as run-off or dewatering during deep excavation it will be disposed in consultation with the NT EPA and Darwin City Council. A permit is required from the Darwin city council to dispose stormwater run-off or waste water to the stormwater drain that runs through the middle of the site.

B.10.2 LNAPL

LNAPL is not anticipated to be encountered during potential future groundwater monitoring or excavation works. However, any collected volumes of LNAPL will be collected and disposed by an appropriately licenced liquid waste contractor.

B.10.3 Solid Waste

Solid non-soil wastes will be disposed by the appropriate waste stream (recyclable or general waste).

C
Appendix C Outline for Development of a Construction and
Environmental Management Plan

This document is provided as an outline and should be further developed once the nature of development at the site is known. Prior to use the document should be reviewed by an environmental auditor.

C.1 Introduction

Redevelopment of the former Shell McMinn Terminal represents a major change in land use at the site and presents the opportunity to expand the Darwin central business district (CBD). The planned end use for the site is designated areas of high and medium density residential development, commercial bulky goods development, with parks and open space for the remainder of the site.

This document presents the outline for development of a Construction Environmental Management Plan (CEMP) for the redevelopment of the site to minimise disturbance to the site itself and surrounding environment.

The CEMP is intended to provide a framework for environmental management of the construction phase of the site as a guideline to the site owner, future developers and development contractors, the Northern Territory Environmental Protection Authority (NT EPA) and the Development Consent Authority (DCA) division of Northern Territory Department of Lands, Planning and Environment (DLPE). The CEMP is also a basis for the site developer to prepare development-specific environmental management procedures.

An environmental management plan (EMP) will be developed by the site owner/developer/development contractors to guide the NT EPA, DCA, future development contractors that may conduct works at the site. Separate construction and development phase and operational phase EMPs will be developed to control land contamination impacts at the site.

The CEMP applies to a range of potential development activities planned for the site. Construction at the site will possibly include, but no be limited to the following types of development:

• High density residential towers
• Medium density residential terraces
• Commercial ‘bulky goods’
• Commercial office space
• Public open space

The types of development described above are those anticipated in the site-specific Human Health and Environmental Risk Assessment (HERA, URS 2013b) and the 53X Audit Statement. Further detail of the exact types, nature and extent of construction planned for the site can only be detailed once the development plan is prepared for the site.

C.2 Background

The site is located at 38 McMinn Street, Darwin, Northern Territory, and comprised a bulk fuel terminal that was in operation since the late 1930s and was decommissioned 2006. The site is located within the Darwin CBD in an area of mixed land use including residential, commercial and light industrial properties. The Northern Territory Planning Scheme indicates that the site is currently zoned CB. The primary purpose of zone CB is to provide for a diversity of activities including administrative, judicial, professional, office, entertainment, cultural, residential and retail and other business activities with a

commitment to the separation of incompatible activities. The land is considered an integral part of the
Darwin Master Plan which included relocation of the terminal activities within Darwin CBD.

C.3 Framework for Environmental Management

The environmental framework is established by Northern Territory (NT) State legislation, guidelines and policies. The principal legislation related to environmental management is the Northern Territory Environmental Assessment Act, the objective of which is to provide for the assessment of the environmental effects of development proposals and for the protection of the environment. The legislation and associated guidelines also apply to the CEMP. The principal legislation related to contamination management is the Northern Territory Waste Management and Pollution Control Act, the objective of which is provide for the protection of the environment through encouragement of effective waste management and pollution prevention and control practices and for related purposes. A suite of Australian Standards, Codes of Practice and the National Environment Protection Measures (NEPM) also apply to environmental issues related to the project.

In the absence of Northern Territory specific guidance documents, frameworks for preparation of CEMPs are available from other state regulatory bodies such as Vic EPA publication 480 http://www.epa.vic.gov.au/~/media/Publications/480.pdf and NSW EPA EMP guidelines at http://www.planning.nsw.gov.au/rdaguidelines/documents/emp_guideline_pub.... The guidelines and this document provide a generic basis for a site-specific CEMP in the absence of detailed information on the exact composition, type and extent of development expected at the site.

C.4 Objectives

The objective of a CEMP is to ensure that residual contamination is adequately managed, including soil and groundwater.

The objective of this document is to act as a guideline for development of a detailed construction and environmental management plan once the development plan for the site is finalised.

The strategic objectives of the CEMP include the following:

• Present mitigation strategies and actions for the prevention of pollution during construction and redevelopment activities;
• To establish a framework for environmental management for all construction activities conducted at
the site over the redevelopment, and operation and maintenance period; and
• Identify the key environmental, heritage and socioeconomic issues that are relevant to construction and redevelopment activities at the site.

The specific construction-related objectives of the CEMP include the following:

• minimisation of mobilisation of contaminated soils and sediment during all types of construction activities;
• minimisation of noise and vibration during construction activities;
• minimisation of odours, greenhouse gases, ozone-depleting gases and dust during construction activities;
• waste minimisation and impacted water management during construction activities;
• effective traffic management during construction activities; and
• protecting ecological habitats within and surrounding the site.

C.5 Ecologically Sustainable Development

Construction activities should be conducted in accordance with principles of ecologically sustainable development (ESD) specific to the Australian National Strategy of Ecologically Sustainable Development, including the following:

• The precautionary principle: If there are threats of serious or irreversible environmental damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation;
• Inter- and intra-generational equity: The present generation should ensure that the health, diversity
and productivity of the environment are maintained or enhanced for the benefit of future generations;
• Conservation of biological diversity and ecological integrity; and
• Improved valuation and pricing of environmental resources.

Works completed at the site to date satisfy several of the principles as stated below:

• The precautionary principle – environmental investigation works have been undertaken at the site between 2006 and 2013 to assess the contamination status of the site, to undertake broad scale soil remediation, to undertake a human health and environmental risk assessment (based on
assumed development scenarios for the site) and preparation of a statement of environmental audit by Dr Peter Nadebaum, a Victorian EPA accredited environmental auditor. The accredited auditor sign-off process is ensuring that any shortfalls in site specific (scientific) information are not being used as a reason for postponing measures to prevent environmental degradation on the site. All measures necessary to prevent environmental degradation and pollution during the remediation, demolition and construction phases of the project will be implemented on a best practice basis. Remediation and future redevelopment of the site represents reduction in degradation of environmental, heritage and socio-economic qualities;
• Inter- and intra-generational equity – prior to commencement of environmental investigation and
remediation works, the site’s levels of contamination (and subsequent health risks), former infrastructure and disused state were disincentives to use the site area and are denying the current generation opportunities for community gatherings, housing, commercial enterprises and a commercial/residential link between the Darwin CBD and surrounding suburbs. Leaving the site undeveloped would also deny future generations the same opportunities to enjoy the site as a home, a place for commerce, gathering and social interaction, thereby preventing inter- generational equity;
• Conservation of ecological biodiversity – site works to date have involved extensive remediation
works of contaminated soils and removal of former infrastructure that would have prevented site redevelopment. The remediation works have reduced contamination and improved the environmental quality of terrestrial habitats. Construction activity will involve construction of buildings and infrastructure including a portion of the site for recreational open space. Where possible, existing terrestrial habitats will be conserved. Remediation works have reduced the potential for exposure of humans and fauna to soil and groundwater contamination; and
• Improved valuation and pricing of environmental resources – the mechanism for valuation and
pricing of environmental resources within the site area will be improved as a feature of remediation and construction works. The value of the site’s environmental resources is implicit in the cost of
the remediation works undertaken to reduce contamination and enable future site use.

C.6 Legislation and Guidelines

C.6.1 Relevant Legislation

The range of potential environmental, heritage and socio-economic issues related to redevelopment at the site may involve a wide range of applicable legislation. Legislation at Commonwealth and Territory level applies at the site for remediation, construction and operational phases of the redevelopment.

C.6.2 Commonwealth Legislation

The following Commonwealth Government legislation has been considered:

• Environment Protection and Biodiversity Conservation Act 1999;
• Ozone Protection and Synthetic Greenhouse Gas Management Act 1989.

Under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), developments require assessment if they have the potential to affect any matters of National Environmental Significance (NES), namely:

• World Heritage properties;
• National Heritage places;
• Ramsar wetlands of international importance;
• listed threatened species and ecological communities;
• listed migratory species;
• Commonwealth marine areas; and
• Nuclear actions.

The redevelopment of the site is unlikely to trigger any matters of NES, nor will any redevelopment affect or be undertaken on Commonwealth land.

C.6.3 Northern Territory Legislation

The Northern Territory Government has jurisdiction over environmental and other legislation relating to the siting, construction and operation of the site. The Environmental Assessment Act 1982 and its implications for the development are discussed in Section 1.3.1. The following is a list of the primary Northern Territory legislative requirements that may have a bearing on the proposed redevelopment.

• Environmental Assessment Act
• Water Act
• Soil Conservation and Land Utilisation Act
• Poisons and Dangerous Drugs Act
• Dangerous Goods Act
• Northern Territory Aboriginal Sacred Sites Act
• Heritage Conservation Act
• Aboriginal and Torres Strait Islander Heritage Protection Act
• Aboriginal Land Rights (Northern Territory) Act
• Waste Management and Pollution Control Act
• Weeds Management Act
• Environmental Offences and Penalties Act

• Ozone Protection Act

Further detail of the key Northern Territory environmental protection legislation can be found at the NT EPA website (http://www.ntepa.nt.gov.au/about-nt-epa/legislation).

C.6.4 Relevant Guidelines

There are a number of policy documents, at a Territory level, that could become relevant considerations once the development proposal is submitted for the site, the most important ones are those relating to the protection of the environment.

The general environment duties under the Waste Management and Pollution Control Act (WMPC Act) require that a person must not undertake an activity that pollutes or might pollute the environment unless the person takes all reasonable and practicable measures to prevent or minimise any resulting environmental harm. Section 4 of the Act defines ‘Environmental Harm’, ‘Material Environmental Harm’ and ‘Serious Environmental Harm’. This, while not an approval per se, is a very powerful statutory tool that needs to be considered in the project.

The WMPC Act provides for implementation of Commonwealth National Environmental Protection Measures (NEPMs) under the National Environment Protection Council (Northern Territory) Act, including the National Environment Protection (Assessment of Site Contamination) Measure 1999 amended 2013.

The surface and groundwater at the site should be assessed in accordance with the Water Quality
Objectives for the Darwin Harbour Region – Background Document (2010)

http://lrm.nt.gov.au/

data/assets/pdf_file/0005/16565/WQGO_for_DH_Feb_2010_final.pdf?_sm_au_

=iVVHNnnRFBhvSvRM. The objective of the guideline is to maintain the beneficial uses of the Darwin Harbour (protection of aquatic ecosystems, recreational water quality and aesthetics under the Northern Territory Water Act). The criteria for assessing water quality are included in the document, assessment criteria for toxicants are based on the Australia and New Zealand Environment Conservation Council (ANZECC) and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) Guidelines for Fresh and Marine Water Quality (2000).

C.7 Management Structure of Redevelopment Activities

The management structure of the site redevelopment is not known at the present time. The key stakeholders who will be involved in development of a management structure will be the site owner, site developer and development contractors, NT EPA, DCA, DLPE and Darwin City Council.

A summary of the management structure and points of contact should be included in the CEMP. Documents that are relevant to environmental management for the project include:
• The five (5) statements of environmental audit describing the restrictions to development posed by
residual contamination across the five (5) development zones at the site..
• The SMP describes the residual soil and groundwater contamination remaining remediation and the associated design, occupational health and safety and environmental management required during the construction and operation phase activities at the site.

Table-C-1 Allowable Development and Restrictions

Development Zones Allowable Development under
Environmental Audit Conditions Non-allowable Development under
Environmental Audit Conditions

No accessible gardens or soil

No accessible gardens or soil
No slab on grade*
No basement car park*

*slab on grade and basement car park may be allowable with consideration of additional engineering controls (e.g. moisture/ vapour barrier beneath slab)

Zone C
MD – medium density
Medium and/or High density residential apartments and/or commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking
— constructed above a basement car park
Residual contamination within Zone C
does not preclude
• Deep excavations
• Swimming pool

No accessible gardens or soil
No restrictions to the type of medium density residential apartments or commercial retail/office space

Zone D
MD-R – medium density with some restrictions Medium and/or High density residential apartments with any of the following scenarios:
— constructed above open ground level parking
Larger scale commercial retail/office space with any of the following scenarios:
— constructed as slab on grade
— constructed above open ground level parking
Smaller scale commercial retail/office space with any of the following scenarios:
— constructed above open ground level parking
Residual contamination within Zone D

No accessible gardens or soil
No medium density residential constructed as slab on grade**
No small scale commercial retail/office space constructed as slab on grade**
No basement car park**

Development Zones Allowable Development under
Environmental Audit Conditions Non-allowable Development under
Environmental Audit Conditions
does not preclude
• Deep excavations
• Swimming pool

C.7.1 Temporary Facilities Required During Construction Phase

Construction activities will require temporary facilities to be erected and installed on the site. Installation of these temporary facilities will enable various site functions to be achieved, including storage of construction materials, office administration and amenities and provision of site security. Temporary facilities required during construction works might include items such as a bulk materials lay-down yard, vehicle wash bays, decontamination facilities for vehicles, fencing and security access control points, contamination control points, portable toilets, waste water utilities, bulk material stockpile areas, demountable offices and lighting.

C.7.2 Workforce Required During Construction Phase

The workforce in construction activities will be appropriately skilled, have appropriate experience and be trained in occupational health and safety. The size of the workforce will fluctuate depending on construction activity. All personnel employed on site during redevelopment works will be required to undergo environmental awareness training to educate them on their responsibilities, communications procedures and requirements, incident response procedures and integration of environmental management and occupational health and safety.

C.8 EMP Framework

C.8.1 Construction EMP

The CEMP will be required as a part of two processes for the redevelopment of the site, namely:

• The DLPE approval process: The CEMP describes the environmental management framework requirements for construction phase activities at the site.
• A basis for the Developer and construction contractors to prepare specific environmental
management procedures.

C.8.2 Contractors EMP

The construction contractors will prepare their own EMP based on the framework of the CEMP. The construction contractor’s EMP will be reviewed and approved by the site owner/developer/development contractors and will form part of the Contractors Contract. The Contractors EMPs will be specific to their contracted services but will consider the impact of their services on other site activities that are or will be occurring at the site during their contracted services.

C.8.3 Contractors Health and Safety Plan and Emergency Response Plan

All contractors will be required to produce a Health and Safety Plan (HASP) and Emergency Response Plan (ERP) to protect their employees during the works they shall undertake. The CEMP shall be considered when preparing each contractor’s HASP and ERP. Environmental controls and exposure levels associated with worker protection shall be included in the contractor’s EMP. Work practices required by the EMP are not intended to compromise health and safety in any way. Each HASP and ERP will be approved by the site owner/developer/development contractors prior to the contractor commencing works. To ensure adequate health and safety controls and procedures have been developed, that are appropriate to the works to be undertaken. A copy of each HASP and ERP will be compiled on a central register held by the site owner/developer/development contractors.

C.8.4 Continuous Improvement

The CEMP is based on an environmental management system of continuous improvement that includes the following steps:

• planning;
• implementation and operation;
• checking and corrective action; and
• management review.

The planning stage of this system is based on describing:

• the activities to be undertaken and their associated potential impacts;
• the site conditions;
• the methodology for the activity, preventative measures, inspections, monitoring and auditing;
• the performance indicators and targets; and
• the actions to be undertaken if the targets are not met.

The implementation and operation stage of the system is based on:

• conducting the activity and preventative measures.

The checking and corrective action stage of the system is based on:

• conducting the inspections, monitoring and audits, and assessing corrective action when targets have not been met and reporting; and
• conducting and reporting corrective actions.

The management review is based on:

• review of checking and corrective actions; and
• implementing changes at the next planning stage.

C.9 Key Management Plans

C.9.1 Overview

Each of the environmental, heritage and socioeconomic issues discussed in this section are presented as key management plans (KMP). The KMPs are derived from the works undertaken at the site to assess, remediate and characterise risks to human health and the environment resulting from residual

contamination. The listed KMPs do not exclude additional issues as they may arise once the development proposed for the site is known or during the construction phase. All KMPs include proposed measures to minimise adverse impacts, monitor effectiveness of safeguards and report the progress and effectiveness of each of the key management plans as part of an overall continuous improvement process over the life of the CEMP. Due to the conceptual nature of the development scenarios presented in the statement of environmental audit, the KMPs presented here are strategic in content, yet provide sufficient detail to enable monitoring and reporting procedures to be developed for each KMP.

It must also be noted that several criteria apply across a range of environmental issues. Contamination and meteorology are broad categories that each affects a number of the KMPs in various ways. Contamination may be present in soil at the site as well as within groundwater. Meteorology has the potential to affect stormwater, erosion and sediment control, groundwater, damage to structures, nearby marine water quality and so forth. Mention of each of these criteria will be made within each relevant KMP where relevant.

The management strategies for each of the KMPs are related to activities conducted during construction and development of the site. There may be some overlap or repetition of the management strategies and subsequent monitoring and reporting requirements throughout the KMPs. Where aspects of KMPs are not known at this point in time they should be detailed at the time of redevelopment.

C.9.2 Breakdown of KMPs

The components of the KMP are detailed below:

Management Commitments

The management commitment or overarching philosophical environmental management principle of the site owner/developer/development contractors during the construction and development phase of the site is described for each of the KMPs.

Management Strategies

Management strategies that intend to prevent, or minimise adverse environmental impacts have been prepared for each KMP for activities under the CEMP. The management strategies include, prohibition, moving or minimising certain activities to prevent or minimise impact as well as implementing control measures that are designed to prevent or minimise adverse environmental impacts from certain activities.

Monitoring Programs

Monitoring program requirements are summarised for each KMP to monitor adverse environmental impacts. The Contractor will also be required to confirm conformance with the performance indicator targets that will be required in their EMPs. Upon breeching these performance indicator targets reactive monitoring programs are to be activated as part of the response mechanism to minimise and manage any adverse environmental impacts.

Reporting

The recommended reporting requirements for each KMP are summarised in the following sections.

C.9.3 Residual Soil and Groundwater Contamination

Residual soil and groundwater contamination has been characterised at the site and may be encountered during subsurface activities during construction and redevelopment works. The impacts to human health from direct contact, ingestion and dermal contact with contamination of soils and groundwater have been assessed in the site specific HERA (URS 2013b). Discharge of contaminated groundwater to the nearby marine environment has been considered unlikely.

Management Commitment
To ensure the protection of human health and the environment by minimising and managing exposure to residual
soil and groundwater contamination at the site during construction and redevelopment at the site.
Management Strategies
• Potential direct contact with contamination should be limited by barriers between humans and the residual contamination. Barriers could include personal protective equipment (gloves, long sleeves and pants) and administrative controls such as avoiding direct contact and washing hands and face prior to eating, drinking and smoking).
For all zones of the site, risks to on- and off-site intrusive workers from exposure to contaminated soil, groundwater and vapours are low and acceptable, when working above the bedrock level.
Contamination occurring within bedrock has not been assessed
• In the lower central portion of the site as defined in the SMP contaminated soil is covered with not less than
1 m of non-contaminated cover, this buffer should be maintained as far as practicable during works and re- established at the completion of works. Where excavation of this material is required the non-contaminated
cover should be kept separate to prevent mixing with potentially contaminated deeper soils and rock.
• The extent and rate of excavation of potentially contaminated spoil should be controlled and minimised.
• Excavation and storage of odorous soils should be minimised. Stockpiling and transporting odorous loads must be covered, including ventilation and potential use of spray deodorants if appropriate.
• Contaminated soils must be transported off-site as soon as possible to a licensed facility using appropriate tracking procedures for movement of contaminated spoil including documented volumes, tonnages, receiving site, acceptance receipts and approval from the NT EPA if required.
• Diversion drains may be required to collect contaminated surface runoff, particularly from wash down areas.
• Contaminated stormwater from stockpiles and wash down areas to be intercepted and treated prior to discharge to sewer or stormwater with appropriate approval from NT EPA, Darwin City Council and/or PowerWater Corporation. These will integrate with the natural drainage characteristics of the site where possible.
• Excavation equipment will be washed down before entry and exit to the site to avoid the migration of contaminants. Designated wash down areas are to be constructed with appropriate drainage and treatment facilities.
• Contaminated groundwater or stormwater to be stored for treatment and analysis prior to discharge to sewer or stormwater with appropriate approval from DCC and/or PWC.
• Hydrocarbons and solids collected during contaminated groundwater treatment will be disposed of to an appropriately licensed facility using appropriate tracking procedures.
• A liner is required to underlie contaminated soil or contaminated debris in stockpiles.
• Water applied to contaminated soils for the purposes of dust control must not generate surface water run-off.
• The exposed area of contaminated soils vulnerable to dust generation must not exceed the capacity of water cart/trucks.
• Vehicles exiting contaminated areas must be suitably cleaned (broom swept and wheel wash) to ensure that no residual soil contamination leaves the defined work areas.
• Excavated odorous soils will be either removed from site as quickly as possible or returned to the same location as removed.
• Buildings must be constructed to comply with any consideration stipulated in the statement of environmental audit.
• Basement car parks in must have appropriate ventilation systems as required by the Australian Standard.
• During sub-surface construction of basements, an increased level of appropriate ventilation and confined space management may be required to assure protection of the health of construction workers.
• Subsurface conduits, pipelines, sumps and pits must be constructed to comply with any consideration

stipulated in the statement of environmental audit.
• Connections between below ground structures such as building footings, foundations, piles, basements and services must be constructed to comply with any consideration stipulated in the statement of environmental audit.
• Appropriate facilities including clean-up kit(s) and transport equipment to manage spills and leaks of liquid wastes.
• Topsoil cover shall be provided to the root depth of the plant species proposed.
• Screening and covering of potentially offending soil aesthetics with top soil.
• Appropriate Personal Protective Equipment (PPE) must be worn by all personnel operating at the site, all site personnel should be aware of management procedures for working around potentially contaminated soil and groundwater.
• A survey for UXO at the site has been undertaken by G-Tek, this should be reviewed prior to works at the site.
• Personnel working on site are to be trained and educated of the dangers of UXO, their potential locations and identification features.
• Procedures for reporting and dealing with UXO must be prepared.
• In the event that a UXO is discovered, work shall stop immediately at the site and the area sealed-off.
• Qualified UXO technicians will make safe and dispose of any identified UXO.

Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before the relevant construction activity.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Dust monitoring will be conducted at the site boundary during drilling, excavation, stockpiling and building activities. Dust collected from areas with surface contamination may be analysed for the contaminants of concern.
• Accumulated groundwater and stormwater quality monitoring will be conducted for dewatering activities prior to discharge as per conditions agreed with NT EPA, DCC and PWC including identified contaminants of concern at the site including total petroleum hydrocarbons.
• Odour monitoring will be conducted for drilling, excavation, and stockpiling activities to ensure odour levels at the site boundary remain at an acceptable level.
• Excavations will require validation testing at their extents for contaminants of concern including total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and heavy metals to confirm that contamination has been removed and that the land is suitable for the intended land use.
• Excavated soil will be assumed to be contaminated and require testing for contaminants of concern including total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and heavy metals prior to on-site reuse or off- site disposal to an appropriately licenced facility. Off-site disposal may require analysis of additional analytes
in order to meet assessment criteria for classification of waste.
• Imported fill will be required to be tested for a range of analytes, to an appropriate standard approved by site owner/developer/development contractors and the NT EPA to confirm that it is clean fill and appropriate for the intended land use prior to being brought onto site.
• Liquid wastes must be removed by a licenced waste disposal contractor. Appropriate testing will be required to characterise the liquid waste and confirm acceptance criteria of the waste facility are met.
• A dedicated liquid waste storage facility will be established on site with appropriate all weather cover and bunding arrangements to prevent discharge.
• A survey for UXO at the site has been undertaken by G-Tek, this should be reviewed prior to works at the site.
Reporting
• A standardised reporting format will be developed and agreed with the site owner/developer/development contractors.
• Reporting of atmospheric emission monitoring, dust monitoring analysis, surface water and groundwater monitoring and complaints received should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D
Appendix D Additional CEMP considerations

D.1 Physical Environment

The following KMPs represent the spectrum of elements that comprise the natural physical environment of the project area. Where possible, reference has been made to the potential ecosystem, built environment and socioeconomic elements of the site.

D.1.1 Air Quality

Atmospheric emissions from anticipated activities at the site include odours, dust generation, particulates, greenhouse gases (GHG) and ozone-depleting gases (ODS). Sources of these atmospheric emissions could include clean and contaminated soil, vehicle emissions, and construction materials (e.g. asphalt and adhesives).

Management Commitment

To minimise and manage environmental impacts from atmospheric emissions during the construction and development of the site. This extends to persons at the site and residents near the site.

Management Strategies

• Odours will be monitored in real time during works and odour suppression spray available on-site during works.
• Water will be applied by water cart/truck whenever unsealed surfaces have the potential to release excessive levels of dust. The exposed area vulnerable to dust generation should be no larger than the capacity of water cart/trucks.
• Ensure construction machinery and vehicles are well maintained and in good working order.
• Stockpiles of soil and vegetative materials prone to the release of dust will be covered or sprayed with water whenever conditions exist for the generation of excessive levels of dust.
• Particulates derived from contaminated soil or potentially hazardous materials will be covered or contained where possible and sprayed if the potential exists for excessive releases of dust.
• Vehicles must not be loaded above the height of the side and tailboards.
• Vehicle emissions will be kept to a minimum by avoidance of unnecessary engine running time.
• Access roads will be sealed and vehicle speeds on unsealed roads will be restricted to minimise dust generation.
• The use of ozone-depleting substances will be avoided.
• Complaints related to atmospheric emissions from stakeholders will be responded to within 48 hours.
Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before the relevant construction activity.
• The results of the monitoring program will be used to measure the effectiveness of the odour and dust control measures against the target
• Odour and dust monitoring will be conducted at the site boundary during any drilling, excavation, stockpiling and building activities.
• Dust collected from areas with potential contamination should be analysed for the contaminants of concern including hydrocarbons.
Reporting
• A standardised reporting format will be developed and agreed with site owner/developer/development contractors and NT EPA.
• Reporting of odour monitoring, atmospheric emission monitoring, dust monitoring analysis results and complaints received from stakeholders should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.1.2 Groundwater

Groundwater beneath the site is contaminated by petroleum hydrocarbons related to historical site use. There are additional potential groundwater quality impacts during the construction and redevelopment of the site. Sources of the impacts may include oil spills, remnant contamination within soils and contaminated surface run-off seeping into the aquifer. It is not considered that there is
potential for groundwater discharge to affect marine water quality or ecology.

Management Commitment
To minimise and manage environmental impacts to groundwater quality during the construction and
redevelopment at the site. This extends to potential impacts to marine waters and ecology 300 m east of the site.
Management Strategies
• Testing of groundwater to ascertain quality in that particular area of the site.
• Testing of accumulated surface water to ascertain quality and inform management options.
• Dewatering and disposal to the marine environment via the stormwater drainage line in the middle of the site will be minimised. Dewatering should be controlled by a Stormwater and Groundwater Management Plan to be developed for the construction and redevelopment of the site.
• Groundwater and stormwater accumulating in excavations will be contained on-site and released into stormwater or sewer in consultation with the NT EPA, Darwin City Council (DCC) and PowerWater Corporation (PWC).
• Effort should be made to maintain a riparian fringe around the stormwater drain through the middle of the site.

Reporting
• A standardised reporting format will be developed and agreed with site owner/developer/development contractors and NT EPA.
• Reporting of groundwater and marine waters monitoring analysis results and complaints received from stakeholders should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.1.3 Noise and Vibration

There is potential for noise and vibration impacts to persons at the site and neighbouring residents from most activities including site clearance, excavation and earthworks, installation of underground services and roadways, construction of buildings and landscaping during the construction and redevelopment phase at the site. Potential noise and vibration sources include the operation of plant and machinery at the site and the use of heavy vehicles on and off site.

Management Commitment
To minimise and manage environmental impacts from noise and vibration during the construction and redevelopment of the site. This extends to persons at the site and residents near the site.
Management Strategies
• Work must be undertaken in the agreed working hours.
• Removal of noise sources from noise sensitive location.
• Construction activities within close proximity to sensitive receptors must only occur in limited and agreed

Appendix D - Additional CEMP considerations

D.1.4 Erosion and Sediment Control

There are potential impacts due to erosion, sediment deposition within the site and to the marine waters and ecology and adjoining the site during the construction and redevelopment of the site. Sources of these impacts include oil spills, vehicle traffic and roads, disturbed soil, stockpiles, gross pollutants, and surface pollutants.

Management Commitment
To minimise and manage environmental impacts at the site from erosion during construction and redevelopment of the site. This also extends to impacts to nearby marine waters 300 m east of the site.
Management Strategies
• Stockpiles to be protected from stormwater flows.
• The size and area of stockpiles of soil will be minimised.
• Land clearance will be minimised.
• Where possible, activities at the site are to be undertaken during the dry season to reduce the potential for erosion and off-site transport of sediments.
• Stormwater management including erosion control and sedimentation measures at the site will be controlled by an Erosion and Sedimentation Control Plan (E&SCP) for the construction and redevelopment of the site.
• Constructed slopes with the potential for erosion will be minimised and surface cover will be retained where

possible or added to disturbed land.
• Erosion potential of stockpiles will be minimised by reducing batter slopes and including bunding where appropriate.
• Works will be planned and conducted to maximise the opportunity to retain sediment on site.
• Stockpiles that may be susceptible to erosion must be covered or include suitable erosion control measures such as silt fences and hay bales.
• Temporary cut off drains, bunding, and other sediment control measures such as sediment traps, hay bales,
silt fences and sediment basins, grass swales and buffer strips will be used to capture sediments and nutrients during construction activities where possible and appropriate.
• Gross pollutants, sediments, oils and other contaminants from hardstand, roadway and trafficked areas will be captured by specialised measures including oil, grit, and gross pollutant traps where possible and appropriate.
• Roadways will be swept to remove dust, organic matter and pollutants.
• Access roads will be sealed and vehicle speed on unsealed roads will be restricted to minimise erosion.
Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before the relevant construction activity.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Stormwater quality monitoring will be conducted for stockpiling activities at the discharge points from the site for identified contaminants of concern at the site including pH, salinity, suspended solids, turbidity, total petroleum hydrocarbons, and nutrients.

Reporting
• A standardised reporting format will be developed and agreed with site owner/developer/development contractors and NT EPA.
• Reporting of stormwater monitoring analysis results and complaints received from stakeholders should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.2 Biological Environment

D.2.1 Terrestrial Fauna

The likelihood of encountering fauna of conservation significance during the construction or operation phases of the project is very low due to the lack of suitable habitat within the study area to support the specialized resource requirements of species. Any fauna of conservation significance that are likely to be encountered will probably be primarily transitory (e.g. birds).

Management Commitment
To limit the impact on terrestrial fauna from construction and redevelopment of the site.
Management Strategies
• Installing temporary fencing adjacent to significant vegetation.
• Minimising land clearing during construction activities.
• A register of significant fauna that may periodically be encountered within the development site will be maintained. Construction staff will be notified of the importance of recording such fauna in the register.
Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before construction activities.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Recording the presence of resident or transitory terrestrial fauna on a central fauna register for the site. This

Appendix D - Additional CEMP considerations

register will be available to NT EPA for monitoring and review.
Reporting
• A standardised reporting format will be developed and agreed with site owner/developer/development contractors and NT EPA.
• Reporting of resident and transitory fauna will be finalised every 12 months and forwarded to the owner/developer and NT EPA as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.2.2 Biting Insects

Biting insects at the site represent a potential threat to human health and the reduction in public amenity. In this situation, biting insect assessments concentrate on mosquitoes and biting midges, of which mosquitoes are capable of transferring potentially fatal diseases such as Murray Valley encephalitis virus (MVEV), diseases caused by Kunjin virus (KUNV), Ross River virus (RRV) and Barmah Forest virus (BFV). Their abundance at the site is highest between August and January and at all times of year during the full and new moon phases of the lunar cycle http://www.health.nt.gov.au/Medical_Entomology/Insect_Pest_Periods/index.... The bite of a biting midge can cause a painful reaction to humans, as well as resulting in some secondary infection. There is also a threat of infection by exotic mosquitoes, introduced by vessels originating from outside Australia.

Management Commitment

To minimise and manage biting insects at the site during the construction and development of the site through a
program of preventative and protective measures.

Management Strategies

• Draining, filling and grading current mosquito breeding sites, where possible.
• Minimising ponding and poorly draining areas capable of holding water during construction activities.
• Clearing existing stormwater drains of sediment where possible.
• Where feasible, reengineering of existing drains to reduce the potential for ponding.
• New stormwater drainage must be designed to minimise ponding at the site.
• Removing artificial receptacles capable of providing habitat for larvae after rainfall events before construction activities commence.
• Landscaping plans for the site should include shrubs resistant to bifenthrin to enable insecticide barrier treatment to control adult biting mosquitoes and avoid plants capable of ponding water.
Monitoring
• A standardised system of regular monitoring should be developed and conducted.
• Baseline monitoring is to commence before the relevant construction activity.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Biting insect surveys will be conducted prior to construction activities commencing and to provide baseline information. Six monthly assessments will then be carried out during construction and redevelopment of the site.
• Complaints by stakeholders related to biting insects at the site will be recorded.
Reporting
• A standardised reporting format will be developed and agreed with the site owner/developer/development contractors.
• Reporting of biting insect surveys and complaints received from stakeholders should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.3 Built Environment

D.3.1 Roads and Public Transport Network

Traffic for construction activities at the site will include the use of heavy (and light) vehicles. These tasks will include the delivery or transport of soils and construction materials and the transfer of construction personnel to, from and within the site. The potential impacts related to the road and public transport networks include noise and vibrations, air emissions, unsecured/uncovered loads, traffic congestion, safety issues to the public accessing the site or neighbouring car parking, and collision of traffic with vehicles, humans or fauna.

Management Commitment
To minimise and manage impacts related to traffic during construction and development of the site.
Management Strategies
• Work must be undertaken in the agreed working hours.
• Consideration will be given to all other site users, not involved in construction activity. Construction activities within close proximity to sensitive receptors must only occur in limited and agreed hours.
• A memorandum of understanding will be developed with relevant stakeholders to ensure that management strategies are agreed and adhered to.
• In the event that road closures are required for construction works, stakeholders will be given prior notice of closure times a minimum of 48 hours in advance.
• Ensure construction machinery and vehicles are well maintained and in good working order.
• Speed limits will be set and observed at the site to minimise dust generation. Access roads will be sealed and vehicle speed on unsealed roads will be restricted to minimise dust generation.
• Heavy vehicles will obey speed limits already set in the Darwin City area.
• Vehicles will not be loaded above the height of the side and tailboards.
• All loads to and from and the site will be covered and restrained to prevent the loss of materials.
• Vehicle emissions will be kept to a minimum by avoidance of unnecessary engine running time.
• All complaints involving vehicle movements relating to construction activity will be responded to within 24 hours and action taken within 48 hours.

Appendix D - Additional CEMP considerations

development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.4 Construction Activities

D.4.1 Drilling, Excavation and Stockpiling, and Dewatering

Drilling and excavation are anticipated during construction and redevelopment at the site. These activities will be required during the construction of buildings, above ground and below ground services, earthworks and landscaping. Potential issues associated with drilling and excavations include dust, noise and vibrations, erosion, mobilisation of contaminants to stormwater and groundwater.

Management Commitment

To minimise and manage impacts from drilling, excavation and stockpiling, and dewatering activities during
construction and development at the site.

Management Strategies

• Drilling, Excavation and Stockpiling
• The drilling and/or excavation contractor will be made aware of the locations of all known heritage-related items and areas and must avoid disturbance to these areas.
• Underground services will be cleared and drilling locations approved by site owner/developer/development contractors and/or the contractor prior to commencing drilling activities.
• Drilling and/or excavation will be undertaken within the agreed working hours.
• Ensure all drilling and/or excavation equipment is well maintained and in good working order.
• Drilling and/or excavation activities within close proximity to sensitive receptors must only occur in limited and agreed hours.
• Where possible, drilling and/or excavation activities at the site are to be undertaken during the dry season to reduce the potential for erosion, off-site transport of sediments.
• Reducing noise where possible and appropriate by using low noise equipment, acoustic barriers and other noise abatement devices.
• Reducing the impact at the receiver at sensitive locations where possible and appropriate by implementing noise insulation treatments such as suitable façade constructions, acoustic ventilation paths and minimisation of structure borne sound transmission paths.
• Stormwater management including erosion control and sedimentation measures at the site will be controlled by an Erosion and Sedimentation Control Plan (E&SCP) during construction and development at the site.
• Drilling and/or excavation activities will be planned and conducted to maximise the opportunity to retain sediment on site.
• During drilling and/or excavation activities, dust suppression will be achieved by spraying water on soils and other materials that may cause dust emissions.
• Vibrations from drilling and/or excavation must be minimised at any neighbouring premises. Residents of neighbouring premises must be warned of possible vibrations prior to the commencing the activity.
• Stockpiles that may be susceptible to erosion must be covered or include suitable erosion control measures such as silt fences and hay bales.
• Stockpiles of excavated soil and vegetative materials that may generate dust should be covered or sprayed with water whenever conditions exist for dust generation.
• Temporary cut off drains, bunding, and other sediment control measures such as sediment traps, hay bales,
silt fences and sediment basins, grass swales and buffer strips will be used to capture sediments and nutrients during construction activities where possible and appropriate.
• Noise complaints will be responded to within 24 hours and mitigation measures checked and improved within
48 hours. Other complaints related to drilling activities received from stakeholders will be responded to within
48 hours.
• Vehicles must not be loaded during excavation activities above the height of the side and tailboards.
• Access roads will be sealed and vehicle speed on unsealed roads will be restricted to minimise dust

generation
• Dewatering
• Where possible, dewatering at the site is to be undertaken during the dry season and contained on-site prior to analysis and discharge to sewer or stormwater with prior approval of DCC and PWC in order to reduce the potential for erosion, off-site transport of sediments and potentially contaminated groundwater or stormwater.
Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before commencing activities.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Dust monitoring will be conducted at the site boundary during drilling, excavation, stockpiling and construction activities. Dust collected from areas with surface contamination may be analysed for the contaminants of concern
• Accumulated groundwater and stormwater quality monitoring will be conducted for dewatering activities prior to discharge as per conditions agreed with NT EPA, DCC and PWC including identified contaminants of concern at the site including total petroleum hydrocarbons.
• Noise monitoring will include noise from plant, machinery and heavy vehicles, truck movements to/from site and within site boundaries and vibration sources.
• All noise complaints shall be recorded and forwarded so that remedial action can be undertaken.
• For activity periods of 4 weeks and under:
• L10 level measured over a period of not less than 15 minutes when the construction site is in operation must not exceed 75 dB(A).
• For activity periods between 4 and 26 weeks and under:
• L10 level measured over a period of not less than 15 minutes when the construction site is in operation must not exceed 65 dB(A).

Reporting
• A standardised reporting format will be developed and agreed with the site owner/developer/development contractors.
• Reporting atmospheric emission monitoring, dust monitoring, noise, stormwater and groundwater monitoring analysis results and complaints received from stakeholders should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.4.2 New Building Construction and Infrastructure

There are numerous new buildings and infrastructure anticipated during redevelopment at the site. Possible impacts from new buildings and infrastructure include air quality, noise, erosion and sediment control.

Management Commitment
To minimise and manage impacts from excavation and land forming activities during construction and redevelopment at the site.
Management Strategies
• Water will be applied by water cart/truck whenever unsealed surfaces have the potential to release excessive levels of dust. The exposed area vulnerable to dust generation should be no larger than the capacity of water cart/trucks.
• Stockpiles to be protected from stormwater flows.
• The size and area of stockpiles of soil will be minimised.
• Land clearance will be minimised.
• Where possible, activities at the site are to be undertaken during the dry season to reduce the potential for erosion and off-site transport of sediments.
• Stormwater management including erosion control and sedimentation measures at the site will be controlled

Appendix D - Additional CEMP considerations

contractors.
• Reporting of odour, dust, noise and stormwater/groundwater monitoring results and complaints received from stakeholders should be prepared by the site owner/developer/development contractors at least annually and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

D.5 Waste Management and Minimisation

Management Commitment
To manage and minimise wastes originating from construction activities, during the construction and
redevelopment of the site.
Management Strategies
• Building waste should be segregated according to appropriate waste stream (i.e. recycling, general waste, contaminated or restricted wastes). Disposal of building waste should be to an appropriately licensed facility using appropriate tracking procedures.
• The extent and rate of excavation of potentially contaminated spoil should be controlled and minimised.
• Excavation and storage of odorous soils should be minimised. Stockpiling and transporting odorous loads must be covered, including ventilation and potential use of spray deodorants if appropriate.
• Contaminated soils must be transported off site as soon as possible to a licensed facility using appropriate tracking procedures for movement of contaminated spoil including documented volumes, tonnages, receiving site, acceptance receipts and approval from the NT EPA if required.
• Diversion drains may be required to collect contaminated surface runoff, particularly from wash-down areas.
• Contaminated stormwater from stockpiles and wash down areas to be intercepted and treated prior to discharge to sewer or stormwater with appropriate approval from DCC and/or PWC. These will integrate with the natural drainage characteristics of the site where possible.
• Excavation equipment will be washed down before entry and exit to the site to avoid the migration of contaminants. Designated wash down areas are to be constructed with appropriate drainage and treatment facilities.
• Contaminated groundwater or stormwater to be stored for treatment and analysis prior to discharge to sewer or stormwater with appropriate approval from DCC and/or PWC.
• Hydrocarbons and solids collected during contaminated groundwater treatment will be disposed of to an appropriately licensed facility using appropriate tracking procedures.
• Water applied to contaminated soils for the purposes of dust control must not generate surface water run-off.
• Vehicles exiting contaminated areas must be suitably cleaned (broom swept and wheel wash) to ensure that no residual soil contamination leaves the defined work areas.
• Appropriate facilities including clean-up kit(s) and transport equipment to manage spills and leaks of liquid wastes.
Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before the construction activities.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Monitoring will include weights, volumes and appropriate waste tracking documentation.
Reporting
• A standardised reporting format will be developed and agreed with the site owner/developer/development contractors.
• Reporting of weight of building waste clean soil, contaminated soil, contaminated water, treated water transported or discharged off site should be prepared by the site owner/developer/development contractors at least monthly and forwarded to the relevant regulatory bodies (if required as part of the development approval and obligations under relevant legislation) as part of the reporting program for the site.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

McMinn SMP

Appendix D - Additional CEMP considerations

D.6 Cultural Environment

D.6.1 Aboriginal Cultural Heritage, Archaeology and Native Title

Management commitment
To ensure the protection of potential aboriginal cultural heritage at and adjacent to the site during construction and redevelopment of the site.
Management Strategies
• The Aboriginal Areas Protection Authority (AAPA) will be contacted prior to redevelopment works to determine if sites of Aboriginal cultural significance are present on or adjacent to the site.
• Where relevant to the site, contactors will be educated about Aboriginal heritage issues at the site including disturbance avoidance measures that may need to be adopted during construction activities. In the event that unknown Aboriginal Sacred Sites or significant artefacts are discovered during construction activities, Contractors will also undergo additional education as deemed necessary by the local Aboriginal community.
Monitoring
• A standardised system of regular monitoring is to be developed and conducted.
• Baseline monitoring is to commence before the construction activities.
• The results of the monitoring program will be used to measure the effectiveness of measures against the target.
• Known Sacred Sites and sites of cultural significance will be inspected to ensure buffer zones have not been breached and confirm disturbance has not occurred.

Reporting
• A standardised reporting format will be developed and agreed with the site owner/developer/development contractors and AAPA if required.
• Reporting of Sacred Site inspections will be finalised every 6 months and forwarded to the site owner/developer/development contractors and AAPA as part of the reporting program for the site.
• Report upon disturbance of Sacred Site or discovery of suspected significant artefact to the site owner/developer/development contractors and AAPA.
• Reporting will consistent with the continuous improvement goals for environmental management for the project.

URS Australia Pty Ltd Level 3, 93 Mitchell Street Darwin, NT 0800
GPO Box 2005, Darwin NT 0801
Australia

T: 61 8 8980 2900
F: 61 8 8941 3920

www.ursglobal.com

Table of contents

Statement of Environmental Audit Zone A ................................................................................................ i Statement of Environmental Audit Zone B .............................................................................................. vi Statement of Environmental Audit Zone C .............................................................................................. xi Statement of Environmental Audit Zone D ............................................................................................ xvi Statement of Environmental Audit Zone E ............................................................................................ xxi
Abbreviations ......................................................................................................................................xxxiv

1. Intro

1.1 duction.....................................................................................................................................1

Background ..........................................................................................................................1
1.2 Purpose................................................................................................................................1
1.3 Input to this report by auditor’s support team ......................................................................2
1.4
Audit legislative requirements ..............................................................................................2

1.5
Issue of Certificates and Statements of Environmental Audit..............................................4

1.6
Documents reviewed ...........................................................................................................4

1.7
Disclaimer ............................................................................................................................7

2. As

2.1
sessment guidelines ..................................................................................................................9

Land use categories.............................................................................................................9

2.2
Beneficial uses of the land to be protected..........................................................................9

2.3
Investigation criteria adopted - land ...................................................................................10

2.4
Site specific soil criteria......................................................................................................12

2.5
Beneficial uses/environmental values of groundwater to be protected .............................13

2.6
Groundwater water quality criteria .....................................................................................14

2.7
Site specific groundwater criteria .......................................................................................15

3. Site definition................................................................................................................................19

3.1 Site definition and description ............................................................................................19

3.2 Validation areas .................................................................................................................20

3.3 Site status at audit commencement...................................................................................20

3.4 Proposed site development and Audit zones ....................................................................21

3.5 Site status at audit completion ...........................................................................................23

3.6 History of use .....................................................................................................................23

3.7 Site soils and hydrogeology ...............................................................................................26

3.8 Surface water .....................................................................................................................28

4. Site investigation activities ...........................................................................................................29

4.1 Chronology of site activities relevant to the environmental audit ......................................29

4.2 Field investigation summary ..............................................................................................31

4.3 Field sampling and laboratory testing program .................................................................32

4.4 Adequacy of the assessor’s investigation program – soils ................................................34

4.5 Adequacy of the assessor’s investigation program – groundwater ...................................36

4.6 Adequacy of the assessor’s investigation program – supporting documents....................40

5. Quality review of the site assessment and auditor verification ....................................................41

5.1 Quality Control and Assurance ..........................................................................................41

5.2 Site visits by auditor ...........................................................................................................41

5.1 Conclusions on QA/QC......................................................................................................43

6. Pre-remediation site condition - soil .............................................................................................44

6.1 Soil assessment prior to site decommissioning .................................................................44

6.2 Soil assessment after decommissioning............................................................................44

6.3 Soil vapour .........................................................................................................................47

6.4 Validation report, URS 2013 ..............................................................................................48

6.5 Other contamination...........................................................................................................54

7. Pre-remediation site condition - Groundwater .............................................................................57

7.1 Historical groundwater monitoring prior to site decommissioning .....................................57

7.2 Groundwater investigation after site decommissioning .....................................................60

7.3 Quarterly groundwater monitoring events 2010-2012 .......................................................66

8. Summary of findings by investigation area ..................................................................................70

9. Remediation works undertaken....................................................................................................71

9.1 Remediation objective........................................................................................................71

9.2 Source removal ..................................................................................................................71

9.3 Land farming program........................................................................................................72

9.4 Excavation and off-site disposal ........................................................................................73

9.5 Validation program .............................................................................................................73

9.6 Effectiveness of the remediation........................................................................................73

9.7 Remediation objectives and end points .............................................................................74

9.8 Groundwater ......................................................................................................................74

9.9 Natural attenuation.............................................................................................................74

9.10 Clean up to the extent practicable .....................................................................................76

10. Site conditions post remediation ..................................................................................................77

10.1 Summary of final condition of the site ................................................................................77

10.2 Nature and extent of residual soil impact...........................................................................77

10.3 Stockpiles (reinstated material) .........................................................................................80

10.4 Groundwater monitoring post remediation.........................................................................81

10.5 Off site................................................................................................................................84

10.6 Nature and extent of residual groundwater impact ............................................................89

10.7 LNAPL................................................................................................................................92

11. Asse ssment of risks at the site ....................................................................................................93
11.1 Beneficial uses to be protected..........................................................................................93
11.2 Objectives and scope of risk assessment..........................................................................93
11.3 Approach to risk assessment.............................................................................................94
11.4 Evaluation of soil contamination ........................................................................................94

11.5 Evaluation of groundwater contamination........................................................................103

11.6 Non-aqueous phase liquid ...............................................................................................109

12. On-going management of soil and groundwater........................................................................110

12.1 Site Contamination Management Plan ............................................................................110

12.2 Development areas ..........................................................................................................110

12.3 Controls on beneficial uses precluded by pollution .........................................................113

12.4 Soil management .............................................................................................................114

12.5 Groundwater monitoring ..................................................................................................114

12.6 Periodic review of management plans .............................................................................116

13. Audit conclusions .......................................................................................................................117

14. References .................................................................................................................................123

Table index

Table 1 Details on the appointment of the auditor and site background ..........................................1

Table 2 Auditor’s team assisting with audit.......................................................................................2

Table 3 Documents reviewed ...........................................................................................................4

Table 4 Additional investigation reports not included in the audit.....................................................6

Table 5 Protected beneficial uses of land .......................................................................................10

Table 6 Soil SSTLs in mg/kg – Top (southern) Section of Site (Area 1) ........................................12

Table 7 Soil SSTLs in mg/kg – Bottom (northern) Section of Site (Areas 2 to 5) ...........................13

Table 8 Protected Environmental Values .......................................................................................14

Table 9 Groundwater quality indicators of relevant beneficial uses ...............................................15

Table 10 Adopted Groundwater Investigation Levels .......................................................................16

Table 11 Site definition and description ............................................................................................19

Table 12 Potential contaminants of concern.....................................................................................25

Table 13 Sequence of site activities .................................................................................................29

Table 14 Summary of soil sampling program ...................................................................................35

Table 15 Summary of groundwater sampling program.....................................................................37

Table 16 Assessor’s site assessment information ............................................................................40

Table 17 Summary of site visits and workshops by the auditor or auditor’s assistants....................42

Table 18 URS 2011 Test pit TPH, BTEX & Lead result exceedences for NEPM EIL & HIL ............51

Table 19 Summary of GMEs prior to decommissioning ...................................................................58

Table 20 Summary of GMEs after decommissioning .......................................................................61

Table 21 Area 1 residual soil impacts ...............................................................................................78

Table 22 Area 2 and 3 Residual soil impacts ...................................................................................79

Table 23 Area 4 Residual soil impacts .............................................................................................80

Table 24 Summary of groundwater sampling impacts and exceedences of Investigation
Levels after remediation.....................................................................................................85

Table 25 Summary of development zones .....................................................................................112

Figure index

Figure 1 Site location plan

Figure 2 Site features

Figure 3 Sampling locations all areas URS 2008, 2011 and 2012

Figure 4 Validation areas

Figure 5 Soil exceedances above adopted guidelines test pits (2011) Figure 6 Excavation locations 2011 and 2012
Figure 7 Soil exceedances above adopted guidelines excavation validation samples
(2011)

Figure 8 Conceptual site model dry season

Figure 9 Conceptual site model wet season

Figure 10 Soil exceedances above adopted SSTLs

Figure 11 Site Management Plan – development zones and restrictions

Figure 12 Site Management Plan – development zones and restrictions with coordinates

Appendices

Appendix A – Figures

Appendix B – NT EPA Correspondence

Appendix C – Reviewed reports

Appendix D – Site inspection notes and photographs

Appendix E – Meeting minutes

Appendix F – Auditor’s QA/QC Review

Appendix G – Additional pre-remediation information

Appendix H – GHD CUTEP report

Appendix I – Glossary of terms

Abbreviations

ANZECC Australian and New Zealand Environment and Conservation Council ARMCANZ Agriculture and Resource Management Council of Australia and New Zealand AS Australian Standard
ASLP Australian Standard leaching procedure

BaP Benzo(a)pyrene

BTEX Benzene, toluene, ethylbenzene, xylene

CoC Chain of custody

DO Dissolved oxygen

EIL Environmental investigation level EPA Environment Protection Authority ESA Environmental site assessment GME Groundwater monitoring event
GQRUZ Groundwater quality restricted use zone

HIL Health investigation level

LOR Limit of reporting L/s Litres per second m Metres
mBGL Metres below ground level mg/L Milligrams per litre
MAH Monocyclic aromatic hydrocarbons mg/kg milligrams per kilogram
NATA National Association of Testing Authorities NEPC National Environmental Protection Council NEPM National Environmental Protection Measure NHMRC National Health and Medical Research Council OCPs Organochlorine pesticides
OPPs Organophosphorus pesticides PAHs Polycyclic aromatic hydrocarbons PCBs Polychlorinated biphenyls
PID Photo-ionisation detector

QA Quality assurance

QC Quality control

RPD Relative percent difference

SEPP State environment protection policy

SVCH Semi volatile chlorinated compounds (Hydrocarbons) SVOCs Semi volatile organic compounds
SWL Standing water level

TCLP Toxicity characteristic leaching process

TDS Total dissolved solids

TIT Triple interceptor trap

TPH Total petroleum hydrocarbons

USEPA United States Environment Protection Authority

UST Underground storage tank

UCL Upper confidence limit

VHCs Volatile halogenated compounds VOCs Volatile organic compounds WHO World Heritage Organisation
μg/L Micrograms per litre

μS/cm Micro seimens per centimetre

GHD | Report for Shell Company Australia - Environmental Audit Report, 22/15171/104595

1. Introduction

1.1 Background

This Environmental Audit Report sets out the results of a Statutory Environmental Audit (the Audit) for the property located at 38 McMinn Street, Darwin, Northern Territory (the Site). The Audit has considered the requirements of:

 The Waste Management and Pollution Control Act NT 1998;

 The National Environmental Protection Measure for Assessment of Site Contamination 1999 (NEPM, 1999);

 The NT Water Act 1992;

 Advice provided by the Northern Territory Environment Protection Authority (NTEPA); and

 The general principles for undertaking audits, as outlined by Part IXD of the Victorian
Environment Protection Act 1970, and the associated policies and guidelines. The location of the Site is shown in Figure 1, Appendix A.
Table 1 presents the details on the appointment of the auditor and details to describe the Site.

Table 1 Details on the appointment of the auditor and site background

Name of Auditor Dr Peter Nadebaum

Term of appointment of Auditor 16 May 1990 to 29 September 2015

Date Audit requested 11 June 2010

Owners of the site Shell Company of Australia Limited

Person requesting a Certificate Peter Oxnam of Shell Company of Australia Limited (SCOA)

Planning Authority Development Consent Authority

Title Information Lot 5649, Town of Darwin

Area of the Site 7.2 hectares

Zoning Central Business under the Northern Territory Planning
Scheme

Address of the Site McMinn Street, Darwin, Northern Territory.

Current Occupier Unoccupied

Site Assessor URS Australia Pty Ltd (URS)

Audit Completion Date 4 August 2014

1.2 Purpose

This Environmental Audit Report sets out the results of a Statutory Environmental Audit for the Site. The Audit has considered the requirements of:

 The Waste Management and Pollution Control Act NT 1998;

 The National Environmental Protection Measure for Assessment of Site Contamination 1999;

 Correspondence from the rom NT EPA, dated 18 June 2013 addressing specific queries from the auditor; and

 The general principles for undertaking audits, as outlined by Part IXD of the Victorian
Environment Protection Act, 1970, and the associated policies and guidelines.

1.3 Input to this report by auditor’s support team

The Auditor’s support team were involved with the Audit. The GHD staff and support team members that assisted with the Audit are provided in Table 2.
Table 2 Auditor’s team assisting with audit

Name Qualification/Role Contribution to audit

Robyn Madsen, Susan Niland, Katrina Rope, Laura Saunders

Auditor’s assistant Preparation of the draft environmental audit report, project management, site inspections, review of numerous correspondence, preparation of various draft letters, preparation of draft advice, review of assessor’s reports.

Joanne Roolker, Natalie Dallaire, Alexander Koscielski, Heidi Small

Auditor’s assistant Data checking and report writing

Eric Friebel Risk Assessor Review of human health and environmental risk assessment document

Victorian EPA approved support team members are underlined.

1.4 Audit legislative requirements

1.4.1 Requirements for an Audit

Shell is undertaking a voluntary environmental audit as part of the arrangements for termination of the lease.

We note that while this is a non-statutory audit, our understanding is that the Northern Territory Environment Protection Authority (NT EPA) requires contaminated land environmental audits to be conducted in accordance with requirements under Part IXD of the Victorian Environmental Protection Act 1970), except where Northern Territory legislation specifies otherwise.

Section 51 of the NT Planning Act (2007) requires the consent authority when considering a development application to take into account, amongst other items:

51(d) an environment protection objective within the meaning of the Waste Management and
Pollution Control Act that is relevant to the land to which the application relates; …

51(g) if a public environmental report, or an environmental impact statement, has been prepared or is required under the Environmental Assessment Act in relation to the proposed development – the report or statement and the results of any assessment of the report or statement under that Act by the Minister administering that Act.

It is presumed that the Site is to be developed, and these requirements will be triggered.

The Northern Territory Waste Management and Pollution Control Act 1998, Section 68 specifies that:

“(1) The Chief Executive Officer must cause to be established and maintained a register of -

(a) persons qualified to perform environmental audits for the purposes of an environmental audit program;”

Currently persons listed on this register include

 ‘persons appointed to be environmental auditors (Contaminated Land) for the purposes of section 53S of the Victorian Environmental Protection Act 1970’; and

 Site auditors accredited under the NSW Contaminated Land Management Act 1997.

Dr Peter Nadebaum of GHD is appointed as an auditor under the Victorian Environment Protection Act, and was appointed through GHD to conduct an environmental audit of the former Shell Terminal at 38 McMinn Street, Darwin.

The audit was undertaken in accordance with Section 47d of the WMPC Act which states that:

An environmental audit is an evaluation of any of the following:

(d) the likelihood of waste management problems or pollution resulting in environmental harm occurring and the adequacy of safeguards in place to prevent their occurrence or limit their impact on the environment.

1.4.2 Audit methodology

The Northern Territory Environment Protection Authority (NT EPA) has not published guidance specific to the conduct of environmental audits. In the absence of such guidance, it has been assumed that the audit should be carried out generally in accordance with the Victorian environmental audit system consisting of Part IXD of the Victorian Environment Protection Act,
1970, and the associated policies and guidelines. The site assessment approach is in accordance with that specified in the National Environmental Protection Measure for Assessment of Site Contamination 1999 (as amended 2013), consistent with the requirements of the National Environment Protection Council (Northern Territory) Act 1994.

Where it is considered that Victorian guidance may be inappropriate, guidance has been requested by the auditor from the NT EPA, such as for the purpose of defining Beneficial Uses at the site, and it has been assumed that such advice overrides requirements within the Victorian legislation. In respect to this submission, the auditor (Dr Peter Nadebaum) wrote to the NT EPA on the 21 May
2013 outlining the approach proposed to the audit for the McMinn Street site. The reply from NT
EPA, dated 18 June 2013, accepted the approach proposed by GHD. A copy of the Auditor’s letter and the response from the NT EPA are provided in Appendix B.

A CUTEP report for the site has been prepared by the Auditor, Environmental Audit, 38 McMinn
Street, Darwin, Clean Up to the Extent Practicable of Groundwater (CUTEP) Report dated April
2014, and submitted to NT EPA on 10 April 2014. (A copy is provided in Appendix H).

GHD received a letter from NT EPA dated 23 May 2014 (included in Appendix B) stating that the NT EPA notes that the auditor considers that the current level of clean up is consistent with Clean up to the Extent Practicable and supports the auditor’s proposed actions with regards to restricted development through an SMP and ongoing groundwater monitoring. The NT EPA will issue a Pollution Abatement Notice (PAN), once the statements of environmental audits are accepted by the NT EPA. The PAN, including the statements of environmental audit, will be placed as a notice of the Land Title and on the NT EPA website, so that the site has appropriate environmental regulatory control.

1.5 Issue of Certificates and Statements of Environmental Audit

The Environmental Audit system provides a mechanism for assuring planning and responsible authorities, prospective purchasers and others that potentially contaminated land is suitable for particular uses. If the contamination status of the Site does not preclude any beneficial uses, then a Certificate of Environmental Audit will be issued. If the Auditor is of the opinion that contamination may render a site unsuitable for some beneficial uses, the Auditor must issue a Statement of Environmental Audit to that effect. The Statement will outline the specific uses that
will not be compromised by the contamination present at the Site, and any conditions or restrictions on activities at the site that may need to be observed.

The Statement will outline the specific uses that will not be compromised by the contamination present at the site, and any conditions or restrictions on activities at the site that may need to be observed.

1.6 Documents reviewed

The following documents have been reviewed for the purposes of the Audit:

Table 3 Documents reviewed

Author Date Document Title

Groundwater Technology Australia Pty Ltd

3 February 1995 Environmental Site Assessment Report, Shell Darwin Terminal, 38 McMinn Street, Darwin, Northern Territory

IT Environmental
(Australia) Pty Ltd

16 February 2001 Groundwater Monitoring Event Report, December 2000, Shell Darwin Terminal – McMinn Street, Darwin, Northern Territory

IT Environmental
(Australia) Pty Ltd

25 January 2002 Groundwater Monitoring Event Report, December 2001, Shell Darwin Terminal McMinn Street (ECK104D) Darwin, Northern Territory

IT Environmental
(Australia) Pty Ltd

19 December 2002 Groundwater Monitoring Event Report, November 2002, Shell Darwin Terminal McMinn Street (ECK104D) Darwin, Northern Territory

Coffey Environments
Pty Ltd

16 October 2006 Environmental Site Assessment Report, Former Shell Darwin McMinn Street Terminal (ECK104D) McMinn Street, Darwin, Northern Territory

URS Australia Pty Ltd 19 September 2008 Environmental Site Assessment, Former Shell Terminal McMinn St Darwin (ECK104D), Northern Territory

URS Australia Pty Ltd 30 July 2010 Draft Report, Site History Review and Summary of Previous Environmental Site Assessments

URS Australia Pty Ltd 2 August 2010 Draft Report, Factual Groundwater Monitoring Event Report, May 2010, Former Shell McMinn Street Terminal
URS Australia Pty Ltd 4 December 2010 Former Shell McMinn Street Terminal
Darwin - Groundwater Monitoring Event,
August 2010

Author Date Document Title
URS Australia Pty Ltd 11 February 2011 Former Shell McMinn Street Terminal
Darwin - Groundwater Monitoring Event,
November 2010
URS Australia Pty Ltd 11 March 2011 Former Shell McMinn Street Terminal
Darwin – Groundwater Monitoring Event,
February 2011
URS Australia Pty Ltd 29 February 2012 Former Shell McMinn Street Terminal
Darwin – Groundwater Monitoring Event,
June 2011
URS Australia Pty Ltd 29 February 2012 Former Shell McMinn Street Terminal
Darwin - Groundwater Monitoring Event,
January 2012

URS Australia Pty Ltd 10 April 2013 Former Shell McMinn Street Terminal Darwin – Groundwater Monitoring Event, June 2012

URS Australia Pty Ltd 10 April 2013 Former Shell McMinn Street Terminal Darwin – Groundwater Monitoring Event, October 2012

URS Australia Pty Ltd 5 July 2013 Final Report, Environmental Validation Report with Addenda, Former Shell McMinn Terminal, Northern Territory. Works completed to April 2013

(URS, 2013a)

URS Australia Pty Ltd 28 August 2013 Clean-up to the Extent Practicable
(CUTEP) Report - Shell McMinn Terminal

(URS, 2013b)

URS Australia Pty Ltd 18 September 2013 Human Health and Environmental Risk Assessment at the Former Shell McMinn St Terminal, Darwin

(URS, 2013c)

URS Australia Pty Ltd 2 December 2013 Former Shell McMinn Terminal – Qualitative PFOS Risk Assessment

(URS, 2013d)

URS Australia Pty Ltd 16 July 2014 Site Contamination Management Plan – Former Shell McMinn Terminal, Darwin

(URS, 2014)

A full copy of each of these reports is included on the CD in Appendix C of this report. Note that the June 2012 and October 2012 GME reports are included as Appendix K of Addendum A of Validation Report.

It is noted that information in reports indicated that additional investigation works were undertaken by Dames and Moore in 1992, and additional groundwater monitoring events were undertaken between September 1995 and February 2000. Details are summarised below in Table 4. These reports were not provided to the Auditor for review. The auditor does not consider this to be a significant omission as extensive soil and groundwater investigation works have been undertaken
in 2006 and 2008, and these can be expected to have provided more a comprehensive and current understanding of the contamination present at the site.

Table 4 Additional investigation reports not included in the audit

Assessor
Available reference
Date of issue
Nature of works
General conclusions
Dames and Remediation Investigation – 19 October 1992 Remediation Placement of 22 Principal contaminants
Moore Darwin Oil Storage Tanks, investigation shallow boreholes identified were TPH and lead.
Unpublished confidential report across the Site, and Impacts in the vicinity of tanks
prepared for the Northern Territory one off-site S5 to S7, 1, 2, 15,
Department of Transport and
groundwater monitoring
downgradient of Tanks S8 and
Works. wells.
8 and fire training area.
Majority of the contamination
was found to be restricted to
surface soils.
Shell No details provided.
September 1995
Groundwater
GME on one
No hydrocarbon impact
Monitoring Event
groundwater monitoring
identified at MB3 (T).
(GME)
well at MB3 (T).

OTEK Australia Groundwater Sampling: McMinn
June 1997
GME
GME on two
Hydrocarbon impact detected
Street Terminal, Bitumen Plant
groundwater monitoring
in well MB2 (T) at a
and Harvey Street Compound,
wells at MB2 (T) and
concentration of 1400 µg/L
Darwin, Northern Territory.
MB3 (T)
and benzene at a
Unpublished confidential report
concentration of 3 µg/L.
prepared for The Shell Company

of Australia.
IT Environmental Groundwater Monitoring Event
February 2000
GME
GME on two monitoring
Hydrocarbon impact detected
Report, Shell Darwin Terminal,
wells MB2(T) and
in MB2(T) at a concentration of
McMinn Street, Darwin, Northern MB3(T). 582 µg/L and at MB3(T) at a
Territory. Unpublished confidential concentration of 110 µg/L.
report prepared for Shell Services
International.

6 | GHD | Report for Shell Company Australia - Environmental Audit Report, 22/15171/104595

1.7 Disclaimer

This statutory environmental audit report titled Environmental Audit Report, 38 McMinn Street, Darwin, NT (“Report”) has considered the requirements of The Waste Management and Pollution Control Act NT 1998 and has been prepared in accordance with the general principles
for undertaking audits, as outlined by Part IXD of the Victorian Environment Protection Act 1970, and the associated policies and guidelines.

The Report represents the Auditor’s opinion of the condition of the site in relation to the presence and impact of contamination at the site and its suitability for beneficial uses stated in the Statement of Environmental Audit at the date the Statement of Environmental Audit is signed. This Report:

1. has been prepared by Peter Nadebaum of GHD Pty Ltd (“GHD”) and his team as indicated in the appropriate sections of this Report for Shell Company Australia;

2. may be used and relied on by Shell Company Australia;

3. may be used by and provided to EPA;

4. may be provided to other third parties but such third parties’ use of or reliance on the
Report is at their sole risk; and

5. may only be used for the purpose as stated in Section 1.2 of the Report (and must not be used for any other purpose).

To the maximum extent permitted by law, all implied warranties and conditions in relation to the services provided by GHD and the Report are excluded unless they are expressly stated to apply in this Report.

The services undertaken by the Auditor and his team in connection with preparing this Report were undertaken in accordance with current profession practice and by reference to relevant environmental regulatory authority and industry standards in accordance with Part IXD of the Environment Protection Act 1970.

The opinions, conclusions and any recommendations in this Report are based on assumptions made by the Auditor when undertaking the audit and preparing the Report. The assumptions are noted in the various sections of this Report.

In undertaking the audit and preparing this Report, the Auditor is required to make judgments regarding the completeness, reliability and accuracy of the information, and the potential for contamination to impact human health and the environment. The Auditor makes these judgments based on the information available, the potential impact of contaminants based on the current scientific understanding of the significance and behavior of contaminants, the specific characteristics of the contaminants matrices and current regulatory policy and legislation. The nature of contaminated site investigations is such that there is always some
uncertainty in these matters; as new information can arise, the science underlying these matters
can change, and regulatory policy and legislation can change. The Auditor and his team have formed their opinion on the basis of the information available and their understanding of the current science and regulatory policy and legislation, applying processes and considerations in accordance with professional practice. It is possible that new information, a changed scientific understanding or changed regulatory policy and requirements will become available in the future that may lead to a different interpretation. The Auditor and GHD expressly disclaim responsibility for changes that arise because of any such new information, changed science or changed regulatory policy or legislation.

The Auditor and GHD have prepared this Report on the basis of information provided by Shell Company of Australia, assessment consultant and others who provided information to GHD (including Government authorities). The Auditor and GHD have verified the information received to the extent practicable and within the scope specified in the Guidelines for Issue of Certificates and Statements of Environmental Audit (Publication 759.2, EPA Victoria, 2014). There is some information which it has not been practicable to verify or check, and the Auditor and GHD are not responsible for this information, including (but not limited to) errors in, or
omissions from, the Report, which were caused or contributed to by errors in, or omissions from, this unverified information.

This Report should be read in full and no excerpts are taken to be representative of the findings of this Report.

2. Assessment guidelines

2.1 Land use categories

The National Environment Protection Council (NEPC), under the National Environment Protection Council Act 1994 formulated the National Environment Protection (Assessment of Site Contamination) Measure in December 1999 (herein referred to as “the NEPM”). All the States and Territories of Australia were signatories to the making of the NEPM, including the Northern Territory under the National Environment Protection Council (Northern Territory) Act
1994.

Section 4.3 in Schedule B (7b) of the NEPM proposes four land use categories representing potential exposure scenarios to soil contamination. These are:

1. Residential;

– Soil accessible; substantial home grown food consumption (with and without poultry);

– Soil accessible; minimal home grown food consumption (less than 10% of diet); and

– Minimal opportunities for soil access (e.g. high rise apartments/fully paved flats or units).
2. Commercial/industrial;

3. Parklands/recreational; and

4. Agricultural/horticultural.

It was noted in the NEPM that agriculture and horticultural investigation levels will be influenced by the Food Standards Code and/or ecological impacts, but requires in-depth attention in its own right and was not considered further. Similarly the residential scenario with substantial home-grown food consumption would have required a site and contaminant specific assessment but since this scenario was not relevant it was not considered further.

2.2 Beneficial uses of the land to be protected

Further to the land uses described above, the Victorian State environment protection policy
2002 (Prevention and Management of Contamination of Land), herein referred to as the Land
SEPP, outlines protected Beneficial Uses associated with land uses. The beneficial uses are:

 Maintenance of natural ecosystems, modified ecosystems and highly modified ecosystems;

 Human health;

 Buildings and structures;

 Aesthetics; and

 Production of food, flora and fibre.

The protected beneficial uses for each of the respective land uses (as defined in the Land
SEPP) are shown in Table 1 of the Land SEPP. This table is reproduced in Table 5.

Table 5 Protected beneficial uses of land

Land Use

Beneficial Use

Maintenance of Ecosystems
Natural Ecosystems 
Modified Ecosystems    
Highly Modified Ecosystems      
Human Health       
Buildings & Structures





 
Aesthetics





Production of Food, Flora & Fibre




The proposed land use at the Site comprises a mix of high and medium density residential, commercial use and public open space.

These correspond to Sensitive use (high density residential), commercial and Recreation/open space, and the protected Beneficial Uses at the Site are therefore:

 Maintenance of Modified and Highly Modified Ecosystems;

 Human Health;

 Buildings & Structures; and

 Aesthetics.

2.2.1 NT Water Act (1992) beneficial uses

The Northern Territory Government document Water Quality Objectives for Darwin Harbour Region – Background Document (February 2010) identifies the beneficial uses for Darwin Harbour that are identified under the NT Water Act (1992, amended 2008) as

 Cultural – recreational (swimming and fishing) and aesthetics (visual amenity).

 Environment – habitat for plants and animals.

These Beneficial Uses are consistent with those that have been identified under the Land SEPP
in the previous section.

2.3 Investigation criteria adopted - land

The NEPM provides investigation levels for soil and groundwater in the assessment of site contamination. The NEPM lists Ecological Investigation Levels (EILs) and Health Investigation Levels (HILs) in Schedule B(1). The NEPM EILs and HILs are referred to in the Land SEPP as the principal objectives to be met to protect the beneficial uses of land.

2.3.1 Ecological protection

The EILs in the NEPM are set for urban land use (comprising city, suburban and industrial areas). Where no EIL exists for an analyte the following hierarchy of criteria were used by the Auditor to assess the potential for ecological impact:

 The Environmental Investigation “B” levels presented in the Australian and New Zealand Environment and Conservation Council & National Health and Medical Research Council (ANZECC & NHMRC) “Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites”, 1992;

 Threshold concentrations for sensitive land use - soils (Table 3) from the EPA of New
South Wales “Guidelines for Assessment of Service Station Sites”, 1994;

 The Dutch Target and Intervention Values provided in MHSPE (2000).

2.3.2 Human health protection

In terms of protecting human health, the following criteria were considered for the Site:

Where the land use is consistent with residential land, the NEPM HIL “A” or “D” criteria were considered depending on the density of the proposed development, i.e.:

 NEPM “A” HILs - Standard residential with garden / accessible soil (home grown produce contributing less than 10% fruit and vegetable intake; no poultry): this category includes children’s day care centres, preschools and primary schools; or

 NEPM “D” HILs - Residential with minimal opportunities for soil access: includes dwellings with fully and permanently paved yard space such as high rise apartments and flats.

In the case of the Site, the NEPM “D” HILs are considered to be appropriate.

Where the land use is consistent with “a park, recreational open space and playing fields or a secondary school”, then the NEPM “E” HILs were considered.

2.3.3 Aesthetics

There are no published criteria specific to assessment of aesthetic impact, however, the Land SEPP states that “contamination must not cause the land to be offensive to the senses of human beings”. The NEPM 1999 also specifies the principle that the soils should not be discoloured, malodorous (including when dug over or wet) nor of abnormal consistency.

2.3.4 Buildings and structures

The Land SEPP requires that “Contamination must not cause the land to be corrosive to or adversely affect the integrity of structures or building materials.” The Land SEPP specifies pH, sulfate, redox potential, salinity or any chemical substances or waste that may have a detrimental impact on the structural integrity of buildings and / or other structures as indicators. The NEPM does not specify particular criteria, and AS2159-1995 Piling – Design and Installation has been considered. Section 6 of this Standard specifies exposure classifications and design specifications based on the potential exposure of steel and concrete piles to sulphate, chloride and pH in soil and groundwater.

2.3.5 Production of Food, Flora and Fibre

The Land SEPP requires that “Contamination of land must not: (i) adversely affect produce quality or yield; and
(ii) affect the level of any indicator in food, flora and fibre produced at the site (or that may be produced) such that the level of that indicator is greater than that specified by the Australia, New Zealand Food Authority, Food Standards Code”

The SEPP specifies any chemical substance or waste including those in the National Environmental Protection (Assessment of Site Contamination) Measure, Schedule B(2), Appendix 1.

2.4 Site specific soil criteria

The applicability of the recently published CRC Care Health Screening Levels (HSLs) has been considered by URS and, when considered using site specific information, URS found that HSLs are not applicable.

Following assessment of soils at the site against the above criteria, in order to evaluate risks posed by residual contamination, URS has undertaken a human health and environmental risk assessment (HERA) and has developed Site-Specific Trigger Levels (SSTLs). The risk assessment is discussed further in Section 11, and a copy of the HERA is provided in Appendix C.

Soil SSTLs have been calculated separately for the top (southern) section of the site (Area 1) and bottom (northern) sections of the site (Areas 2 to 5), to reflect the different unsaturated zone geology observed in these two sections of the site. The SSTLs calculated for each COPC under each potential development scenario are shown in Table 6 and Table 8 below.
Table 6 Soil SSTLs in mg/kg – Top (southern) Section of Site (Area 1)

COPC
Residential Commercial

Slab-on- Basement Open Car Slab-on- Basement
Ground Car Park Park Ground Car Park

TPH C6-C10 70 600 NL 300 1500
Aromatic

TPH C6-C10 490 NL NL NL NL
Aliphatic
TPH C6-C10 140 1200 NL 590 2900
TPH C10-C16 110 970 NL 480 NL
Aromatic
TPH C10-C16 120 NL NL NL NL
Aliphatic
TPH C10-C16 220 1900 NL 950 NL
Benzene 0.50 7.3 130 2. 9 53
Toluene 300 2400 NL 1200 6000
Ethylbenzene 140 1100 NL 570 2800
Xylene 94 790 NL 390 1900
Naphthalene 19 170 NL 82 410
NL Non-Limiting

Table 7 Soil SSTLs in mg/kg – Bottom (northern) Section of Site (Areas 2 to
5)

COPC Residential Commercial
Slab-on-Ground Open Car Park Slab-on-Ground
TPH C6-C10 Aromatic 65 NL 300
TPH C6-C10 Aliphatic 520 NL NL
TPH C6-C10 130 NL 600
TPH C10-C16 Aromatic 119 NL 500
TPH C10-C16 Aliphatic 120 NL NL
TPH C10-C16 210 NL 990
Benzene 0.52 210 3.1
Toluene 260 NL 1200
Ethylbenzene 120 NL 570
Xylene 85 NL 390
Naphthalene 18 NL 86

NL Non-Limiting

2.5 Beneficial uses/environmental values of groundwater to be
protected

GHD proposed in its letter to the Northern Territory Environment Protection Authority (NT EPA) on 21 May 2013 that the Beneficial Uses of the Groundwater should be determined in accordance with the National Environment Protection Measure (Assessment of Site Contamination) 1999 herein referred to as the NEPM). Under the NEPM Schedule B (6)
‘Groundwater is assessed on the basis of its suitability for current or realistic future use’. The NT EPA supported this approach in its response on 18 June 2013 (refer to Appendix B for correspondence).

Schedule B (6) of the NEPM (Assessment of Site Contamination) notes that Australian Water Quality Guidelines and the Australian Drinking Water Guidelines specify six environmental values. They are:

 Aquatic ecosystems;

 Aquaculture and human consumers of food;

 Agricultural water;

 Recreation and aesthetics;

 Drinking water; and

 Industrial water

Previous discussions and correspondence with the NT EPA have indicated that the beneficial uses of agricultural / irrigation, primary contact recreation, potable and industrial uses are not relevant at sites within the Darwin CBD. This was noted in the GHD letter of 21 May 2013 to NT EPA (Appendix B).

Given that the groundwater at the site will sit within the zone where the foundations of buildings and structures will be present, the impact of groundwater on buildings and structures has also been considered.

With respect to groundwater at the site, it is concluded that groundwater should not adversely affect:

 Buildings and structures either on site or off site;

 The beneficial uses of a receiving water (for example if groundwater discharges to down gradient marine aquatic ecosystems), and

 The use of land either on site or off site (e.g. if volatiles are present in the groundwater, or where contaminated groundwater discharges at the surface or can be accessed in
shallow excavations).

The Environmental Values that apply to the site based on the suitability of water for current or future use are listed in Table 8. In this Table entries have not been included for uses that are not relevant at the site.
Table 8 Protected Environmental Values

Environmental
Value

Current Use? Realistic Future Use?

Aquatic
Ecosystems

Offsite – Yes – Frances Bay (marine environment) located approximately
300 m north-east.

Offsite – Yes – Frances Bay (marine environment) located approximately 300 m north-east.

Aquaculture and
Human
Consumers of food

Offsite – No – Frances Bay (marine environment) is located approximately
300 m north-east but is used as
mooring area for fishing boats

Offsite – Possible, if it happens that the Frances Bay operations are relocated to another location.

Recreation and
Aesthetics

Offsite – No. The location of the site (Darwin CBD) and low yields makes groundwater unsuitable for this use (such as make up water for swimming pools). Frances Bay is used as a mooring area for boats and is not suitable for recreation.

Offsite – Possible, if it happens that the Frances Bay operations are relocated to another location.

Buildings and
Structures

Onsite – No. There are currently no buildings or structures located on the site.

Offsite – No. There are currently no buildings or structures located immediately down-gradient of the site.

Onsite – Yes. Piles and basements are likely to sit below the groundwater level.

Offsite – Yes. It is possible that buildings may be built down gradient of the site.

2.6 Groundwater water quality criteria

Groundwater quality objectives are defined in Water Quality Objectives for the Darwin Harbour Region - Background Document (Department of Natural Resources, Environment, The Arts and Sport, February 2010) and ANZECC guidelines for Fresh and Marine Water Quality – Aquatic Ecosystems (95% species protection, marine water). The water quality criteria listed in these various guidelines have been adopted for initial screening purposes. Some of the published guideline values have limited relevance to the site situation, and this is taken into account in the following sections of this report when evaluating exceedances of the guideline values.

The groundwater quality objectives adopted by URS for assessment of groundwater at the site are presented in Table 5-1 of URS CUTEP (URS, 2013b), reproduced below.

Table 9 Groundwater quality indicators of relevant beneficial uses

Beneficial
Use

Objectives Guidelines

Maintenance of Ecosystems

Groundwater shall not cause receiving waters to be affected to the extent that the level of any water quality indicator is greater than the level of that indicator specified in the relevant Water Quality Objectives for the Darwin Harbour Region – Background Document (Darwin WQO 2010).

According to the Darwin WQO, the Site falls within the “middle estuary” of Darwin Harbour and the protection of “mid estuary” water quality objectives is required. The Darwin WQO defers
to the ANZECC guidelines for Fresh and Marine Water Quality
– Aquatic Ecosystems (95% species protection, marine water)
for toxicants.

Darwin WQO 2010 – Mid
Estuary

ANZECC guidelines for Fresh and Marine Water Quality – Aquatic Ecosystems (95% species protection, marine water)

Buildings & Structures

Introduced contaminants shall not cause groundwater to be corrosive to structures or building materials (pH, sulphate, redox potential, salinity or any chemical substance or waste that may have a detrimental impact on the structural integrity of buildings or structures).

Australian Standard
2159-1995 “Piling-Design and Installation” (2009)

Development scenarios

The planned end use for the site is High Density Residential with a portion of the low lying areas of the site to be set aside for open space/parklands, additionally the low lying portion of the site is proposed for Commercial 'Bulk and Goods' and/or Medium Density Residential.

Site specific modelling – URS HERA Section 6.2

2.7 Site specific groundwater criteria

Site-specific groundwater criteria were not developed for assessing groundwater samples.

URS have specified Adopted Groundwater Investigation Levels used for this assessment in the validation report (URS, 2013a). The investigation levels are reproduced in Table 10 below.

URS notes that there were no criteria for TPH. As noted in section 2.5 above, the petroleum hydrocarbon concentrations in groundwater at the site are only required to be assessed as a potential risk to beneficial use of the down gradient (off site) marine ecosystems.

In the case of protection of aquatic ecosystems, exceedences of ecological investigation levels (EILs) indicate that there is a need for further consideration of whether or not impact is likely. In general, “High Reliability” ecological investigation levels (EILs) should be used for screening purposes where these are available, in preference to “Low Reliability” EILs. The low reliability EILs are less reliable; it is possible that they will be conservative and effects will only occur at higher concentrations. High reliability EILs exist for some specific hydrocarbons (such as benzene) and have been used where available; in the case of TPH there is not a high reliability EIL, and Section 8.3.7.21 of the ANZECC 2000 AWQG provides a low reliability number of
7 ug/L, which is far lower than constituent EILs (e.g. for benzene the high reliability EIL is
700 ug/L).

URS notes in the HERA (2013c) that the assessment of potential environmental risks due to groundwater contamination identified at the site has been limited to a qualitative assessment.

Although URS has not considered the low reliability investigation levels for assessment of TPH in groundwater, they have made an assessment of the TPH contamination at the site with respect to the risks to down gradient (off site) marine ecosystems. This has been summarized in the HERA (2013c) report and is further discussed in Section 11.5 of this report.

Table 10 Adopted Groundwater Investigation Levels

Analyte LOR Units ANZECC ANZECC Adopted GIL
2000 2000
- Freshwater - - Marine
95% Water - 95%
Total Petroleum
Hydrocarbons
TPH C6-C9 fraction 20 µg/L
TPH C10-C14 Fraction 50 µg/L
TPH C15-C28 Fraction 100 µg/L
TPH C29-C36 Fraction 50 µg/L
Total TPH C10-C36 fraction 50 µg/L
BTEX Compounds
Benzene 1 µg/L 950 700 700
Toluene 2 µg/L 180* 180*
Ethylbenzene
2
µg/L
80*
80*
o-Xylene
2
µg/L
350
350
Total Xylene
2
µg/L
550
550
Polynuclear Aromatic
Hydrocarbons

Naphthalene
1
µg/L
16
70
16
Acenaphthylene
1
µg/L

Acenaphthene
1
µg/L

Fluorene
1
µg/L

Phenanthrene
1
µg/L
2
Anthracene
1
µg/L
0.4*
0.4*
Fluoranthene
1
µg/L
1.4*
1.4*
Pyrene
1
µg/L

Benz(a)anthracene 1 µg/L
Chrysene 1 µg/L
Benzo(b)fluoranthene 1 µg/L
Benzo(k)fluoranthene 1 µg/L
Benzo(a)pyrene 0.5 µg/L 0.2* 0.2*
Indeno(1,2,3-cd)pyrene 1 µg/L
Dibenz(a,h)anthracene 1 µg/L
Benzo(g,h,i)perylene 1 µg/L
Total PAH calculated µg/L
Phenolic Compounds
Phenol 1 µg/L 320 400 320
2-Chlorophenol 1 µg/L 490 490
2-Methylphenol 1 µg/L
3- & 4-Methylphenol 1 µg/L
2-Nitrophenol 1 µg/L 2* 2*

Analyte LOR Units ANZECC ANZECC Adopted GIL
2000 2000
- Freshwater - - Marine
95% Water - 95%
2,4-Dichlorophenol 1 µg/L 160 160
2,4-Dimethylphenol 1 µg/L 2* 2*
2,6-Dichlorophenol 1 µg/L 34*
4-Chloro-3-methylphenol 1 µg/L
2,4,6-Trichlorophenol 1 µg/L 20 20
2,4,5-Trichlorophenol 1 µg/L 0.5* 0.5*
Pentachlorophenol 2 µg/L 10 22 10
Metals (Dissolved)
Iron 0.05 mg/L 0.3* 0.3*
Lead 0.001 mg/L 0.0034 0.0044 0.0034
Manganese 0.001 mg/L 1.9 0.08 0.08
Nutrients

Nitrate as N
0.001
mg/L
0.16
0.16
Polychlorinated
Biphenyls

Arochlor 1016
<5

Arochlor 1232
<5

Arochlor 1242
<5

Arochlor 1248
<5

Arochlor 1254
<5

Arochlor 1260
<5

Organochlorine
Pesticides (OC)

a-BHC
0.000001
mg/L

Aldrin
0.000001
mg/L

b-BHC 0.000001 mg/L
Chlordane - cis 0.000001 mg/L
Chlordane - trans 0.000001 mg/L
d-BHC 0.000001 mg/L
DDD 0.000001 mg/L
DDE 0.000001 mg/L
DDT 0.000002 mg/L
Dieldrin 0.000001 mg/L
Endosulfan 1 0.000001 mg/L
Endosulfan 2 0.000001 mg/L
Endosulfan sulphate 0.000001 mg/L
Endrin 0.000001 mg/L 0.00002 0.000008 0.000008
Endrin aldehyde 0.000001 mg/L
Endrin ketone 0.000001 mg/L
g-BHC 0.000001 mg/L

Analyte LOR Units ANZECC ANZECC Adopted GIL
2000 2000
- Freshwater - - Marine
95% Water - 95%
Heptachlor 0.000001 mg/L 0.00009 0.00009
Heptachlor epoxide 0.000001 mg/L
Hexachlorobenzene 0.000001 mg/L
Methoxychlor 0.000001 mg/L
Organophosphorus
Pesticides (OP)
Azinphos Methyl 0.000001 mg/L 0.00002 0.00002
Bromophos-ethyl 0.000001 mg/L
Carbophenothion 0.000001 mg/L
Chlorfenvinphos 0.000001 mg/L
Chlorpyrifos 0.000001 mg/L 0.00001 0.000009 0.000009
Chlorpyrifos-methyl 0.000001 mg/L
Demeton-S-methyl
0.000001
mg/L

Diazinon
0.000001
mg/L
0.00001
0.00001
Dichlorvos
0.000001
mg/L

Dimethoate
0.000001
mg/L
0.00015
0.00015
Ethion
0.000001
mg/L

Fenamiphos
0.000001
mg/L

Fenthion
0.000001
mg/L

Malathion
0.000001
mg/L
0.00005
0.00005
Monocrotophos
0.000002
mg/L

Parathion
0.000002
mg/L
0.000004
0.000004
Parathion-methyl
0.000002
mg/L

Pirimphos-ethyl
0.000002
mg/L

Polychlorinated biphenyls 0.000001 µg/L
Prothiofos 0.000001 mg/L
*ANZECC Freshwater 95% (low reliability)

2.7.1 Criteria for PFOS

No Australian guidelines exist for PFOS and PFOA, and URS has compiled relevant international criteria for assessment. These include criteria for soil, drinking water or groundwater, and environmental guidelines. They are provided in URS 2013d, attached as Appendix C of this report.

3. Site definition

3.1 Site definition and description

The description and definition of the site are shown in Table 11.

Table 11 Site definition and description

Aspect Comments

Site Locality The assessor provided a site locality plan and site features plan.
Copies of these are provided as Figure 1 and Figure 2 in
Appendix A.

GIS Coordinate of Site centroid

 GDA 94, MGA Zone 52

Eastings: 700521.497
Northings: 8622101.214
(note that the coordinates for the boundaries of the five Audit Zones are shown in Attachment A)

Area The site encompasses an area of approximately 7.2 hectares.

Surrounding Land Use North: Immediate: Vacant Crown Land (Lot 4244),

Further: Tiger Brennan Drive, Frances Bay Mooring Basin and Frances Bay 300 m NE, Kumbutjil Aboriginal Association 300 m NW.

East: Immediate: Frances Bay Drive/Tiger Brennan Drive and high density residential.

Further: France Bay industrial area and Fisherman’s Wharf precinct.

South: Immediate: McMinn Street, car parking, a mechanical repairs workshop and high density residential.

Further: Darwin CBD

West: Immediate: Barneson Street, high density residential and commercial outlets.

Further: Frogs Hollow Park, St Marys Primary School and high density residential.

Topography The site forms an open amphitheatre created by the escarpment on the site. The western portion of the site (Area 1) is approximately 10 m higher than the rest of the site and is formed of flat escarpment with a ridge running between the former drum shed and welding workshop. On the eastern side of the ridge the site falls away to the east and north east (Areas 2, 3 and 4). On the eastern end of the site the escarpment bounds the property (Area 5) and from this side the site falls to the west back to the centre of the property.

Vegetation At the time of audit completion, the site was covered with vegetation, which appeared in good health.

Water Bodies There are two water bodies within 300 m of the site. The former railway reservoir (now known as one mile dam) at the Kumbutjil Aboriginal Association (One Mile Dam Community) is less than 300 m to the NNW of the site. Frances Bay Mooring Basin, Frances Bay and further Darwin Harbour are situation from 300 m to the NE of the site.

Sampling Locations The assessor’s soil sampling, groundwater monitoring well, and validation sampling locations are shown in Figure 3 (Appendix A).

This information satisfactorily defines the site for the purposes of the Audit.

3.2 Validation areas

URS has divided the Site into five validation areas defined by topography, localised geology, localised hydrogeology and previously reported hydrocarbon impact. The areas are shown on Figure 4 (Appendix A). URS’ description of the validation areas is reproduced below.

Area 1

Located in the western corner of the Site and comprises the elevated portion of the Site. The main entry to the Site is located in Area 1 which was the operational hub formerly consisting of administrative, maintenance and road transport loading areas for bulk and drummed petroleum products.

Area 2

Located between the northern site boundary and the former east-west sealed road through the centre of the Site. The area consists of the lower unsealed portion of the Site and former infrastructure consisted of the ships manifold (junction valve for bulk product delivery by ship), ASTs 1, 2, 4 and 14, retention basin and slops AST S8 and associated above and underground pipework.

Area 3

Located between the south western site boundary, the former east-west sealed road through the centre of the Site, the escarpment that defines the eastern edge of Area 1 and the storm water drain running south west to north east through the Site. The area consists of the lower unsealed portion of the Site formerly with a large earthen bund running parallel to the Site road. The area behind the earthen bund forms a large seasonal swamp. Former infrastructure consisted of ASTs 3, 8, 11 and S9, associated pipework, a valve exchange manifold, fire water tank no. 1 and a retention basin.

Area 4

Located between the eastern site boundary, the escarpment to the south of former ASTs 9 and
10 and the storm water drain running south west to north east through the Site. The area consists of the lower unsealed portion of the Site in the eastern corner of the Site. Former infrastructure consisted of ASTs 9, 10 and 15, and associated pipework.

Area 5

Located between the eastern site boundary, the escarpment to the south of former ASTs 9 and
10 and the storm water drain running south west to north east through the Site. The area consists of a lower unsealed portion and higher outcrop of the escarpment to the centre of the south eastern boundary. The area was used as a fire training ground prior to 1996. No petroleum related infrastructure was located in this area.

3.3 Site status at audit commencement

The site is located in a central business district and is zoned CB (central business), and surrounded by mixed uses including high density residential, commercial, Frances Bay Mooring Basin, open land, low density housing, the Kumbutjil Aboriginal Association housing and One Mile Dam, and further from site is Frances Bay, parklands and a primary school.

During the initial site inspection by the Auditor on 2 July 2010, the following observations were noted.

 The site was unoccupied.

 There was some infrastructure on the site including eight ASTs, these were noted by the Shell representative as being stored on the site only and were not part of the operating site infrastructure.

 Vegetation was present and healthy apart from the burnt area in the vicinity of former
Tanks 1 and 2.

 Water was flowing through the creek line/stormwater drain that ran from south to north on the north-eastern end of the property.

 A concrete slab was present on the south western part of the site.

 Some underground pipework was observed in the northern section of the site protruding from the soil.

The site had been occupied by Shell Company of Australia Ltd since circa 1937 up to 2005 when the site was closed. It has only operated as a bulk fuel terminal in this time. At the time of the site inspection all major infrastructure had been removed from the site. There were no buildings or original site ASTs present on the site. The remaining pipework on the site was believed to be mostly aboveground prior to any intrusive investigation being undertaken on the site.

Former site features are shown on Figure 2 of this report (Appendix A).

Photographs of the site are contained in within the auditor’s site inspection reports in Appendix D
of this report.

3.4 Proposed site development and Audit zones

The site is proposed to be developed for a mix of high and medium density residential development, commercial bulk and goods development, with parks and open space for the remainder of the site.

For the purposes of the audit, the site has been divided into five zones based on “suitability for site uses”, and the assumed development scenarios for the site being a mixture of high and medium density residential development, commercial bulk and goods development, with parks and open space for the remainder of the site.

The five zones have been surveyed and are defined in Attachment A at the start of this report, and the restrictions on development for each area are described in the Statements of Environmental Audit statements, and the SMP (URS, 2014) (included as Attachment B).

Zone A

 Approximately 25,479 m2

 Located in the western corner of the Site and comprises the elevated portion of the Site.

 Allowable uses are high density residential and commercial apartments constructed as slab on grade or with a basement car park.

 There is no restriction on the type of high density residential/commercial apartments within Zone A.

Zone B

 Approximately 1,779 m2

 Located centrally and wholly within the southern portion of Zone A.

 Shallow soil impacts remain that may pose an unacceptable vapour intrusion risk to slab on grade residential buildings.

 Allowable uses are high density residential and commercial apartments constructed above an open, ground level car park.

 Non allowable uses (without additional assessment) include residential/commercial apartments constructed as slab on grade, or buildings with basement car parks.

Zone C

 Approximately 15,783 m2

 Forms a broad “Y” shape through the central and south eastern portion of the site. It is located between the south western and south eastern site boundaries, the base of the Zone A escarpment, the Zone E boundary in the northern limb of the “Y” and the Zone D boundary in the centre and eastern limb of the “Y”.

 Allowable uses are medium density residential and commercial apartments constructed as slab on grade; and buildings with a basement car park. If a basement car park is proposed, it can be expected to include a moisture/vapour barrier beneath the basement slab to prevent water ingress during the wet season when the water table is high.

Zone D

 Approximately 17,279 m2

 Forms an arrow shape in the eastern corner and centre of the site. It is located between the eastern and north eastern site boundary, Zone E to the north and Zone C to the west and south.

 There is residual soil impact at depths of greater than 1 m that may pose an unacceptable vapour intrusion risk to slab on grade residential buildings.

 Allowable uses are medium density residential or small scale commercial constructed above an open ground level car park; large scale commercial (bulky goods/warehouse) constructed as slab on grade; and buildings with a basement car park. If a basement car park is proposed, it can be expected to include a moisture/vapour barrier beneath the basement slab to prevent water ingress during the wet season when the water table is high.

 Non allowable uses (without additional assessment) include residential apartments or small scale commercial constructed as slab on grade.

Zone E

 Approximately 4,236 m2

 Located in the northern corner of the site between the north eastern site boundary, the base of Zone A escarpment to the west, Zone C to the south and Zone D to the south east.

 There are residual groundwater impacts that may pose an unacceptable vapour intrusion risk within habitable structures, but these impacts do not pose an unacceptable risk to human health for open space.

 Allowable uses are open space parklands and gardens.

 Non allowable uses (without additional assessment) include enclosed habitable structures.

3.5 Site status at audit completion

During the final site inspection by the Auditor’s assistant on 30 April 2014, the following observations were noted:

 The site was unoccupied.

 The only remaining infrastructure on the site included four empty ASTs, these were noted as being stored on the site only and were not part of the operating site infrastructure.

 As the inspection was conducted at the end of the wet season the vegetation had grown significantly and was covering most of the site.

 No odours were noted.

3.6 History of use

The site history review undertaken by the Auditor was based on the following information:

 Review of information provided by the assessor in the environmental investigation reports.

 Review of previous environmental investigation reports.

 Search of EPA Victoria’s and NT NRETAS records (including a review of list of issued certificates and statements of environmental audit, a review of the list of treatment and disposal facilities for prescribed wastes and a review of the Priority Sites Register).

 Review of historical aerial photographs made available by the assessor.

 Review of the information provided on the only historical certificate of title available for the site.

 Review of documents from the Australian National Library for Darwin from 1919-1926.

 Review of historic maps and records.

 Review of Acid Sulphate Soil (ASS) hazard maps and guidelines for NT.

3.6.1 Onsite history of use

The site forms part of the Darwin city escarpment. It was originally broken up into several parcels of land in the late 1800s for sale. The parcels of land were consolidated in the current allotment some time post 1926 and was held as Crown land and unoccupied in its natural state until Shell purchased the site circa 1930 and commenced operation as the Shell Terminal in
1937.

The site was established for bulk storage and handling of hydrocarbon products.

Most of the vegetation on the site had been removed for the development. The exception was some large boundary trees and a narrow riparian zone along the Area 5 drainage line that remained on the site up until the final site inspection in 2012. The assessor has indicated that the tanks were established on the site from 1930 through to 1980 and all tanks were decommissioned in 2006. The 1969 aerial imagery indicates that the workshop, filling gantry,
main office, drum shed and associated concrete pad, and a number of small ASTs were present on the western portion of the site (Area 1). These structures do not appear to have been modified significantly over the operating period of the site from review of the aerial photography made available. The sites bulk fuel facilities included three underground storage tanks (USTs) and 19 above ground storage tanks (ASTs) storing a combined volume of: 12,704 kL Jet Fuel;
6119 kL Leaded Petrol; 5744 kL Automotive Gas Oil (AGO); 3503 kL Avgas; 531 kL Slops;
165 kL Lube Oil; 100 kL Diesel/Jet Fuel Additive (SAP); 15 kL Jet Blend; and 2.25 kL waste oil.

Through the 1990s several consultants were brought onto the site to undertake environmental site assessments and installation of a small number of groundwater monitoring wells to assessment soil and groundwater contamination across the site.

The site was closed for operation in October 2005 and the following year all infra-structure was removed from the site including 19 ASTs and three USTs, filling gantry, workshops and drum storage area. The only infrastructure that remained on the site was the office building and the oil traps (emptied).

More detailed contamination assessments were conducted in 2006 and 2008 with the installation of 45 groundwater monitoring wells and a number of different soil investigations carried out across the site. These assessments concluded that bulk contamination had occurred on the site and that further works were required to understand the delineation of groundwater contamination and to remediate the unconsolidated soils on the site.

The remaining site infrastructure that was constructed with asbestos containing material (ACM) was removed from the site during 2009. Monitoring conducted during and post removal concluded that no ACM remained on the site.

A number of sources of contamination were identified on the site and during 2011 sites works were undertaken for the remediation of the material on the site including vegetation removal, test pit investigations, removal of remaining site infrastructure (concrete and bitumen) and bulk
soil remediation works. The concrete slabs located in the south western portion of the site (Area
1) were removed during these works.

3.6.2 Offsite history of use

The Darwin CBD was settled and developed in the late 1800s. No roadway infrastructure had been developed along McMinn Street up until 1926. During the 1920s the railway line from Pine Creek was located to the northeast of the site through to Stokes Hill Wharf. The railway reservoir, now known as One Mile Dam (part of the Kumbutjil Aboriginal Association) was located approximately 300 m north-west of the Site. The Palmerston and Port Darwin rifle club range was located approximately 400 m north of the site and was present up until the mid-
1940s to early 1950s. A sanitary depot and cattle quarantine reserve was located 1 km
northwest of the site and was in use up until the late 1960s.

It is understood that around the 1940s when Shell had purchased the Site and had established site operations that Vacuum Oil (Mobil Oil) occupied a lot on Daly Street to the north northwest of the site. The surrounding areas were broken down in residential lots. Frances Bay had not been developed and remained a mangrove coastline. The Naval Fuel Installation located south of the site and had nine ASTs on the site and was established prior to World War II.

Prior to 1969 the CBD and the roadway infrastructure had been well developed. Caltex had purchased and partially developed, with two of the three ASTs on site unfinished (no cover on the tanks) and only part of the Vacuum oil site is visible in the 1969 aerial image and appears similar to the 1981 image.

By the 1980s the Darwin CBD was being re-established following Cycle Tracey in 1974 the Caltex site to the northwest of the Site had four ASTs on site, two of which did not have covers on the tanks in the 1981 aerial image. The Vacuum (Mobil) Oil site further north west had four large ASTs on the site. Fishermans Wharf had been constructed to the south east on Frances Bay, and the area to the northeast of the site remained covered in mangroves.

By the early 1990s the BP site located north of the site and had 11 ASTs on the site. Fishermans Wharf and the adjoining precinct were mostly complete and the Frances Bay Mooring Basin had been established with minimal remnant mangrove vegetation within the vicinity of the site. The Kumbutjil Aboriginal Association had established housing surrounding the pond to the north of the Site and Tiger Brenan Drive was in construction.

During the late 1990s the Caltex site to the northwest of the site had been dissembled and no infrastructure was observed on the site in the 1999 aerial image. The Mobil Oil and BP sites remained in similar condition with similar infrastructure to the 1991. The Frances Bay Mooring Basin had been completed, the Tipperary Waters development further north of this had started construction and Tiger Brenan Drive had been completed.

The Mobil Oil and BP fuel depots were demolished in the early 2000s and have either been assessed (Mobil) or remediated for housing developments (BP). The Caltex site has also been remediated and was for sale at the time of the final site inspection in 2012.

Smaller commercial operations have occurred in vicinity to the site over time including but not limited to mechanical repairs workshop (one currently still in operation), panel beaters, spray painters, retail outlets, and car sales yards. Many of these businesses have since ceased operation and have been demolished and replaced with high density residential dwellings.

Of the operations that have existed offsite many have the potential to cause contamination. Few however are located upgradient of the site. The only Shell infrastructure that had been developed, stored or operated offsite was the fuel pipelines that were noted to exist along the north-eastern/northern boundary fences.

3.6.3 Potential contaminants of concern

The potential contaminants of concern identified from the site history description are summarised in Table 12.
Table 12 Potential contaminants of concern

Site activity/Source Potential Contaminants of Concern Location

On Site

Fuel tanks TPH, BTEX, PAH, Lead

Fuel pipelines TPH, BTEX, PAH, Lead

Fuel storage TPH, BTEX, PAH, Lead

Fill TPH, BTEX, PAH, Metals, OC and
OP

Drains (possible preferential pathway for contamination)

TPH, BTEX, PAH, Lead

Fire training area PFOS/PFOA, surfactants

Site activity/Source
Potential Contaminants of Concern
Location

Bombing during WWII

Buildings on site
UXO

Asbestos

Off Site

Fuel Pipelines (minor leaks)

Fuel Spill (dates unknown)
TPH, BTEX, PAH

TPH, BTEX, PAH
North and east of the site

Northern boundary

3.7 Site soils and hydrogeology

The soil and groundwater borelogs recorded at the site are contained within Volume 3 Appendix B of the assessor’s Phase 2 report (URS, 2008), which is contained within Appendix C of this report.

3.7.1 Soils

The assessor indicated that fill is present on the site in the lower portions of the site (Areas 2, 3 and 4). Fill was noted as being present during site works as a base material for former ASTs (Areas 2, 3 and 4) and as backfill for formers USTs (Area 1). The assessor indicated in the validation report that depth of the fill was approximately 0.5 m at former AST locations and up to
4 m at former UST locations, bund walls and retention basins in the lower portion of the Site
(Area 2 and 4).

The Assessor’s borelogs indicated that soil at the site generally consisted of:

 Fill material of gravely silts and clays underlain by.

 Phyllite or Porcilanite Bedrock.

3.7.2 Regional geology

The 1:100 000 Darwin Geological Map (Northern Territory Geological Survey) indicates that the underlying geology of the site consists of;

 The Darwin Member forms part of the Bathurst Island Formation and is composed dominantly of a white siliceous siltstone containing numerous radiolarians and overlays the Proterozoic Burrell Creek Formation.

 Early Proterozoic, Burrell Creek Formation deposited in sequences of the Pine Creek Geosyncline. This material comprises siltstone; shale; sandstone (quartz arenite, sublitharenite) and quartz pebble conglomerates that have metamorphosed to greenchist facies, commonly referred to as phyllite.

 The Burrell Creek Formation is overlain by Lower Cretaceous Mesozoic Bathurst Island Formations. This material comprises radiolarian claystone, sandy claystone, clayey sandstone, quartz-sandstone, ferruginous sandstone, glauconitic sandstone and basal conglomerate.

3.7.3 Local geology (site)

The assessor indicated that the local geology on the site can be broken down by:

 Pale white porcellanite, a low grade metamorphic claystone, underlain by orange brown phyllite, a low grade metamorphic siltstone with a micaceous foliation in Areas 1, 4 and 5.

 Clayey silty gravel underlain by orange brown phyllite in Area 2.

 Gravelly clayey silt alluvium underlain by orange brown phyllite in Areas 3 and 2.

 Fill material – Present as a base material for former ASTs (in Areas 2, 3, 4) at a depth of approximately 0.5 m and backfill for former USTs (Area 1) at a depth of up to 4 m. Fill is also present in bund walls and retention basins in the lower portion of the site (Areas 2 and 4) and is up to 4 m in depth.

3.7.4 Groundwater flow system

Groundwater in the Darwin area is typically encountered in low transmissivity fractured rock aquifers of the Burrell Creek Formation, with reported yields of 0.5 – 5.0 L/s (NRETAS, 2006). Depths to groundwater vary significantly with the season. During the wet season the water table can be at ground level, dropping to 10 m below ground level during the dry season.

Regional groundwater flow on the Darwin escarpment reflects the topographic drainage lines. Darwin is situated on a peninsular that extends southwards into Darwin Harbour with groundwater flowing away from the shed lines (topographic ridges). The site is defined by a natural amphitheatre that opens to the northeast; inferred groundwater flow at the site reflects the topography. Hydrogeology is considered to be structure controlled (i.e. flow paths along fractures and geological structure planes) through Area 1 and structure controlled at the Fill/Residual Soil boundary and within the phyllite in Area 2. Areas 3 and 4 hydrogeology is defined by unconsolidated material and phyllite bedrock.

The average depth to groundwater is approximately 1 to 6 mBGL. Groundwater response to seasonal rainfall patterns can cause the water table to fluctuate by up to 4 or 5 m. Tidal influence has not been observed at on site bores consistently over time. Only two bores on site have recorded brackish TDS (MW109, MW110) with singular records of salty conditions at MW109 (19045 mg/L, August 2010). Most of the offsite bores to the north and northeast of the
site have recorded brackish to salty TDS (MW112, MW113, MW117, MW119, MW121, MW122)
up to 42,705 mg/L (MW122 mg/L, August 2010).

The presence of a locked mooring at Frances Bay is considered to moderate or negate any local tidal effect on groundwater. Inferred groundwater flow is to the northeast, and likely discharge is at the shore line of Frances Bay and Darwin Harbour

3.7.5 Groundwater database

The assessor undertook a search for registered groundwater bores located within a 1000 m radius of the site was using the Northern Territory Land Information System Database from the Northern Territory Government. The results indicate that there were 81 registered groundwater bores within a 1000 m radius of the site. All except six registered bores were located in neighbouring former petroleum sites, the Naval Fuel Installation (NFI) or the Waterfront Precinct and are listed as for environmental monitoring purposes.

Of the bores not located on petroleum sites, NFI or Waterfront Precinct, two were listed as having no use (RN004598 Eh No 1 Bennett St, RN006137 BMR Woods St), three were listed as use not known (RN002767 Hotel Well Darwin Hotel, RN002768 Ford A Lameroo Lodge, RN002900 Well 4367 Cavenagh St) and one was listed as production (RN020742 Presbytery Well 1459 Smith St). All of these wells were located up hydraulic gradient of the site, within the Darwin CBD.

Darwin CBD is supplied with a domestic water supply. Aquifer characteristics available from Northern Territory Land Information System Database suggest the aquifer to be of low yield. It is considered that the likelihood of groundwater future extraction for human consumption on-site to be unlikely.

3.7.6 Groundwater TDS

The Burrell Creek Formation aquifers are known to be suitable for potable supply, garden watering and other domestic activities based on a TDS of around 1000 mg/L. Information available on the Northern Territory Land Information System Database and data collected on the site indicated that the aquifer was also low yielding (<0.5 L/s), and there were no known users of the groundwater in the vicinity of the site. As discussed in Section 2.5, previous discussions and correspondence with the NT EPA have indicated that the beneficial uses of
agricultural / irrigation, primary contact recreation, potable and industrial uses are not relevant at sites within the Darwin CBD. It has been considered that the beneficial use of groundwater is limited to:

 Protection of marine aquatic ecosystems, located approximately 300 m down-gradient of the site.

3.8 Surface water

The western third of the site is approximately 10 m higher than the central and northern areas of the site. From the western corner of the site where the site office, former workshops, filling gantry and drum stores were located, the site falls to the north and north-west. The central and
eastern two thirds of the site fall gently to the north east. An unnamed stormwater channel/creek
runs from south to north through the site and drains into Frances Bay commercial mooring and
Darwin Harbour, situated approximately 300 m to the east of the site.

The area behind the earthen bund at the north eastern extent of Area 3 forms a large seasonal swamp. Seepage at the base of the escarpment has been noted during the wet season. No other natural drainage lines are present on the property, most possibly due to previous land modification and earthworks.

4. Site investigation activities

4.1 Chronology of site activities relevant to the environmental audit

The chronology of site activities relevant to the environmental audit is presented in Table 13.

Table 13 Sequence of site activities

Date Site Activity Report
October 1994 Groundwater Technology Groundwater Technology Australia Pty
International (GTI) completed an ESA Ltd, Environmental Site Assessment on the Site including a soil gas Report, Shell Darwin Terminal, 38 survey, the drilling of sixteen (16) soil McMinn Street, Darwin, Northern bores (SB1-SB16) and the installation Territory, 3 February 1995
of three monitoring wells (MB1(T) – MB3(T)), sampling of existing MWC1.

December 2000 IT Environment conducted a GME on IT Environmental (Australia) Pty Ltd, two monitoring wells (MB2(T) and Groundwater Monitoring Event Report, MB3(T)) December 2000, Shell Darwin Terminal
- McMinn Street, Darwin, Northern
Territory, 16 February 2001

December 2001 IT Environment conducted a GME on IT Environmental (Australia) Pty Ltd, two monitoring wells (MB2(T) and Groundwater Monitoring Event Report, MB3(T)) December 2001, Shell Darwin Terminal
McMinn Street (ECK104D) Darwin, Northern Territory, 25 January 2002

November 2002 IT Environment conducted a GME on IT Environmental (Australia) Pty Ltd, one monitoring well (MB3(T)) Groundwater Monitoring Event Report,
November 2002, Shell Darwin Terminal
McMinn Street (ECK104D) Darwin, Northern Territory, 19 December 2002

October 2005 The Site was closed.

Circa March
2006

August – September 2006

March/June
2008 The Site was decommissioned, and included the removal of primary sources of petroleum hydrocarbons, being: 19 aboveground storage tanks (ASTs), three underground storage tanks (USTs), associated pipework, mechanical workshop, drum shed, welding workshop, old rail siding, four oil traps (remain on site and had been emptied) potential dumping areas and fuel filling gantry.

Coffey Environments conducted an ESA which included the installation of twenty-three (23) monitoring wells (MW1-MW23) and nine (9) soil bores. Monitoring wells MB1(T) to MB3(T) were lost/destroyed.

URS conducted an ESA on-site which included the installation of fifty-nine (59) soil bores, twenty-two (22) monitoring wells, the installation and sampling of ten (10) soil gas bores, excavation of five (5) test pits where seasonal water logging prevented drill rig access, and the removal of three (3) interceptor pits. A GME was then conducted on the 45 existing monitoring wells.

Coffey Environments Pty Ltd, Environmental Site Assessment Report, Former Shell Darwin McMinn Street Terminal (ECK104D) McMinn Street, Darwin, Northern Territory

URS Australia Pty Ltd, Environmental Site Assessment, Former Shell Terminal McMinn St, Darwin (ECK104D), Northern Territory, 19
September 2008

Date Site Activity Report

March 2009 McMahon Services Australia (NT) Pty Ltd conducted demolition and removal of asbestos containing material
(ACM) at the former main office and toilet block.
Monitoring and verification was undertaken by AEC Environmental during and at the completion of works.

March 2010 URS conducted a GME on 43 monitoring wells (2 off-site wells destroyed since 2008)

11 June 2010 Auditor engaged

2 July 2010 Auditor and the auditor’s assistants conducted a site visit to view current site conditions.

30 July 2010 URS desktop review and data gaps analysis report

August 2010 URS conducted a GME on 42 monitoring wells (3 off-site wells destroyed since 2008)

November 2010 URS conducted a GME on 40 monitoring wells (1 on-site well and 4 off-site wells destroyed since 2008)

February 2011 URS conducted a GME on 37 monitoring wells (3 on-site wells were inaccessible due to seasonal flooding,
1 on-site well and 4 off-site wells destroyed since 2008)

June 2011 URS conducted a GME on 38 monitoring wells (2 on-site wells were inaccessible, 1 on-site well and 4 off- site wells destroyed since 2008)

18 October 2010 Workshop held with URS, GHD and Shell regarding the proposed remediation and goals

July 2011 Remedial activities commence on the site including vegetation removal, test pit investigation works, concrete and bitumen removal, bulk soil
remediation works

July 2011 Auditor and the auditor’s assistant conducted a site visit to view the investigation progress.

October 2011 Validation activities commence on the site. Source removal and land
farming.

McMahon Services, Close out report for Administration office at the old Shell terminal, McMinn Street, Darwin. Demolition and Asbestos removal, February/March 2009
(included as Appendix L of URS 2013a)

URS Australia Pty Ltd, Draft Report, Factual Groundwater Monitoring Event Report, March 2010, Former Shell McMinn Street Terminal.

URS Australia Pty Ltd, Draft Report, Site History Review and Summary of Previous Environmental Site Assessments.

Meeting minutes provided in Appendix
E

December 2011 Site activities are completed. URS Australia Pty Ltd, Draft Report, Environmental Validation Report. Report includes GMEs since March
2010

January 2012 URS conducted a GME on 33 monitoring wells (1 on-site and 5 off- site wells were inaccessible/unable to be located, 2 on-site and 4 off-site wells destroyed since 2008)

Date Site Activity Report

14 June 2012 URS conducted a human health and environmental risk assessment

URS Australia Pty Ltd, Draft Report, Human Health and Environmental Risk Assessment at the Former Shell McMinn Street Terminal, Darwin. (URS
2013c) (Report updated in September
2013)

4 September
2012

June – November 2012

Project workshop held in Melbourne with GHD, URS and Shell.

Additional work to address data gaps:
- delineation and removal of impacted soil in the vicinity of the former fuel gantry and drum shed in Area 1.
- Assess impacts around MW07 and installation of MW201-MW207 to delineate
- Characterisation of hydrocarbon impact in the vicinity of MW02, MW03, MW07, MW09 where TMP was identified in soil vapour

Meeting minutes provided in Appendix
E

Environmental Validation Report – Addendum A – Works completed June to November 2012 (URS 2013a, Appendix R), June 2012 and October
2012 GMEs

March – April
2013

Targeted groundwater monitoring Environmental Validation Report – Addendum B – Works completed to April 2013 (URS 2013a Appendix S)

August 2013 URS complete CUTEP Report Clean-up to the Extent Practicable (CUTEP) Report - Shell McMinn Terminal
(URS, 2013b)

10 September
2013

September – October 2013

25 February
2014

Meeting with NT EPA held in Darwin Meeting minutes provided in Appendix
E

PFOS sampling in groundwater Technical Memorandum – Former Shell McMinn Terminal – Qualitative PFOS Risk Assessment (URS, 2013d)

Issue of CUTEP to NT EPA Environmental Audit, 38 McMinn Street, Darwin, Clean Up to the Extent Practicable of Groundwater (CUTEP) Report (GHD, 2014)

30 April 2014 Final site inspection conducted by
Auditor’s assistant

23 May 2014 Correspondence received from the EPA advising that the authority was satisfied that Clean Up to the Extent Practicable had occurred.

17 July 2014 URS complete SMP including GMP
and CEMP for the site

4 August 2014 Completion date of the Audit.

Letter reference EN2013/0038-0021 (Included in Appendix B)

Site Contamination Management Plan – Former Shell McMinn Terminal, Darwin
(URS, 2014)

4.2 Field investigation summary

Historical investigation works were undertaken at the Site between 1995 and 2002. The works involved preliminary environmental site assessment and groundwater monitoring events of two groundwater monitoring wells that were since destroyed during site works. The reports have been reviewed as background information for the Audit; however the more recent investigations undertaken by Coffey (ESA 2006) and URS (ESA 2008, HERA 2013 and Validation Report
2013) form the basis of the Audit.

The primary field works undertaken across the Site were the Phase 2 ESA investigations undertaken to characterise contamination at the Site in two stages, firstly by Coffey (2006) and secondly by URS (2008). Subsequently remediation works and validation sampling were conducted on the site in 2011 and 2012, and a Validation Report and Human Health and Environmental Risk Assessment (HERA) were produced in 2012. The reports were further amended and finalised in 2013. Throughout 2010 to 2013 frequent groundwater monitoring was conducted on the site by URS. Details of the field investigations are provided in Sections 6-10 of this report.

4.3 Field sampling and laboratory testing program

The laboratory testing program was designed by the assessor to characterise the natural soils and any fill materials on site. The testing was undertaken by the following laboratories:

 Australian Laboratory Services (ALS)

 LabMark (formerly MGT)

 SGS

These laboratories are NATA accredited for the testing undertaken. For the 2008 ESA, MGT was used as the primary laboratory, and ALS was used as the secondary. For the works reported in the Validation report, including investigations undertaken in 2011, additional work in
2012 and GMEs from 2010 – 2013, ALS was used as the primary laboratory with Labmark and
SGS used as secondary laboratories. The sampling and testing program undertaken by the assessor can be summarised as follows.

4.3.1 Soil

Phase 2 Coffey (2006)

A total of 84 soil samples were collected and submitted for laboratory analysis from 32 targeted locations across the site. Fourteen of 84 samples were collected to represent shallow samples (0.0-0.5 mbgl), 21 samples were collected at depth (3.0-8.0 mbgl) and 49 samples were collected from depths of 0.6 m to 2.9 mbgl. Analyses were completed for:

 TPH

 BTEX

 Metals

 PAHs

 Phenols

Phase 2 URS (2008)

A total of 745 soil samples were collected and 299 submitted for laboratory analysis from 89 targeted locations during the installation of soil bores, monitoring wells and undertaking test pits. Sample depths ranged from 0.5 to 9.5 mbgl. Analyses were completed for:

 TPH

 BTEX

 Metals

 PAHs

 Phenols

Soil Gas Survey URS (2008)

Soil Gas survey was undertaken on 17 March 2008 including the installation of nine soil gas bores. One was installed to 0.9 mbgl, four were installed to 1.0 mbgl and four from 2.5 to
4.2 mbgl all soil bores were left for a minimum of seven days before sampling.

Helium leak detection tests were undertaken prior to sample all nine soil gas bores.

Validation Report URS (2012)

A number of samples were taken for various aspects by URS for the site. They are summarised below:

Soil bores:

 Non-Impacted Cover Fill – 16 locations, 122 samples

Test pits:

 PAHs and Phenols - 50 locations , 349 samples

 TPH, BTEX, and Pb – 46 locations, 351 samples

 OCP, OPP and PCB – 18 locations, 73 samples

 Metals, chlorinated hydrocarbons, surfactants – 38 locations, 300 samples

Groundwater bores

 Historical groundwater gauging results – 45 locations (wells), 314 samples taken over time

 Groundwater physico-chemical field parameters – 45 locations, 312 samples

 Historical groundwater analytical results - Shell Type I – 45 locations, 308 samples

 Historical groundwater natural attenuation results – 14 locations, 68 samples

Stockpile samples

Initial stockpile land farming results:

 TPH, BTEX, Pb - four locations (from the four stockpiles). A total of 169 samples

 PAH and Phenols - four locations, 169 samples

 OCP, OPP and PCB – four locations, 169 samples

 Cation Exchange Capacity - four locations, 81 samples

Final land farming results:

 TPH, BTEX, Pb – four locations, 128 samples

 PAH and Phenols – four locations, 128 samples

 OCP, OPP and PCB – four locations, 128 samples

 Cation Exchange Capacity – one location, 41 samples

Land farm excavation validation samples:

 TPH, BTEX, Pb – four locations, 54 samples

 PAHs and Phenols – four locations, 54 samples

 OCP, OPP and PCB – four locations, 54 samples

Road base samples: Samples taken within other testing.

4.3.2 Groundwater

The testing and sampling program conducted by the assessor during the groundwater monitoring events was based on identified contaminants of concern.

The details of the analytical schedules are described further in Section 7.

4.4 Adequacy of the assessor’s investigation program – soils

The entire site is approximately 70,200 m2 (7.02 ha). As discussed in Section 3.2, the assessor divided the site into five areas defined by topography, localised geology, localised hydrogeology and previously reported hydrocarbon impact. Table 14 outlines the soil sampling program that was undertaken by the assessor. The Australian Standard (AS 4482.1) indicates that for areas greater than 5 hectares, the site should be divided into smaller areas. For each of the areas, the number of samples required by Table E1 of AS 4482.1 to detect circular hot spots of contamination with a confidence of 95%, added to a total of 124 sample points across the site arranged in a grid over the site. While the sampling density was below the Australian Standard
in one of the five areas of the Site, the total number of samples analysed for the site in its entirety was well above that required in AS4482.1. The detailed site history was provided for the site and it indicated that there was a lack of potential sources of contamination within Area 5
that would require a high density of sampling in this area.

Approximately 835 samples were analysed from a total of 244 sampling locations across the site during the three stages of works. Note that validation samples from excavation are not included in this summary.

The auditor considers that the investigations have been appropriate for characterising soil conditions at the site. In this, the auditor has considered:

 The number of soil bores and depth of those bores drilled across the site;

 The number of soil bores and the geology within those bores that have been converted to groundwater monitoring wells across the site;

 The number of test pits and the observations made during excavations across the site;

 The number of surface (road base) samples collected and the resulting analysis from
Area 1;

 The consistency of the data collected across the site with the site history information, the site layout and known infrastructure,

 The reliability of the data as evidenced by quality control checks, and

 The experience of the assessor in undertaking this type of work.

Table 14 Summary of soil sampling program

Area Size
(ha)

2006 Sampling Locations
(Coffey)

2008 Sampling Locations (URS) 2011 Sampling
Locations (URS)

2012 Sampling locations
(URS)

AS4482.
1

Total

(approx)

Soil Bores

Soil bores converted to monitoring wells

Road Base
Test Pits Soil Bores Test Pits
Test Pits

Monitoring wells

push tubes

1 2.27 5 6 2 0
14 25 20 1 17 35
90
2 1.75 3 8 2 0
19 30 0 6 30
68
3 1.58 1 6 1 4
16 13 0 25
41
4 0.68 0 3 1 1
6 7 0 17
18
5 0.71 0 0 3 0
3 7 0 17
13
Offsite 0 0 13 0
1 0 0 -
14
Total 7.02 9 23 22 5
59 82 20 7 17 124
244

GHD | Report for Shell Company Australia - Environmental Audit Report, 22/15171/104595 | 35

4.5 Adequacy of the assessor’s investigation program –
groundwater

The groundwater investigation program has been summarised in Table 15. A total of four groundwater monitoring wells (GMWs) were installed on the former Shell McMinn Street Terminal site prior to the Coffey 2006 ESA. A further 23 GMWs were installed by Coffey in 2006 on the site and offsite and an additional 22 GMWs were installed by URS across site and offsite in 2008. In September 2012, seven additional groundwater monitoring wells were installed in
the northern corner of the site to delineate previously identified groundwater impact at MW07. Complete details of these investigations are provided within the ESAs provided in Appendix C.

Groundwater monitoring events (GMEs) have been undertaken on the site from October 1992 through to April 2013. A maximum of two samples were collected from four GMWs located on
the north, western and southern boundaries on the site on an annual basis from 1992 through to
2002. These four GMWs had been destroyed by 2006 and a total of 23 GMWs were installed, sampled and analysed as part of the Coffey ESA (2006). The 23 wells included nine bores on the site and 13 bores offsite, with the majority offsite to the northern and north-eastern boundaries of the Site.

URS conducted frequent monitoring in 2010 (May, August, November), 2011 (February, June) of the majority of wells on site and of selected wells in 2012 (January, June, October) and 2013 (April). Some GMWs were not sampled during every round as some were destroyed during remedial activities, some were dry and some were inaccessible due to the wet season inundation. During the January 2012 GME none of the boundary wells were accessible due to surface water inundation caused by rainfall.

The auditor considers that the investigations have been appropriate for characterising groundwater conditions at the site. In this, the auditor has considered:

 The number of wells formerly surrounding the site characterising the aquifer(s);

 The number of wells currently present at the site;

 The number of sampling rounds undertaken within the bores;

 The consistency of the data collected across the site with the site history information, the site layout and known infrastructure;

 The reliability of the data as evidenced by quality control checks; and

 The experience of the assessor in undertaking this type of work.

Table 15 Summary of groundwater sampling program

Well ID Area Plume Oct-92 Sep-95 Mar-97 Oct-99 Dec-00 Dec-01 Nov-02 August/ September
2006 March/ June
2008
May-10 Aug-10 Nov-10 Feb-11 Jun-11 Jan-12 Jun-12 October- April -13
12
MWC1 Unknown X Destroyed
MB1 Unknown Destroyed

MB2 NW Boundary
X
X
X
X
X
MB3 SW Boundary X X X X X
MW1 1 Top X X X X X X X X X X X
MW2 1 Top X X X X X X X X X X X
MW3 1 Top X X X X X X X X X X X
MW4 1 Top X X X X X X X X X X X
MW6 1 Top X X X Dry well X X X Destroyed

MW23 1 Top X X X X X X X X X X Not sampled

MW101
1
Top X
X
X
X X X X X X Not sampled
MW103 1 Top X
X
X X X X Dry X X

MW117 Offsite North Area 1 X
X
X
X X X
Not
Sampled X X X

MW118 Offsite North Area 1 X
X
X
X X X
Not
Sampled X X X

MW119 Offsite North Area 1 X
X
X
X X X
Not
Sampled X X X

MW102 Offsite North west Area 1 X
X

Dry well
X X X
Not
Sampled
Not
Sampled Dry Not sampled

MW114 Offsite North west Area 1 X

Destroyed

MW115 Offsite North west Area 1 X X X
Destroyed

MW108 Offsite West Area 1 X X X X X X X X X Not sampled
MW7 2 Bottom X X X X X X X X X Dry X

MW8
2
Bottom X X X X X X X X X Dry Not sampled
MW9 2 Bottom X X X X X X X X X X

MW10 2 Bottom X X X X X X X X Dry Dry Not sampled

MW11 2 Bottom

X X X X X X X X X *analysed as solid –
high sediment

Not sampled

MW15 2 Bottom X X X X X X X X X X X MW16 2 Bottom X X X X X X X X X X Not
sampled

Well ID Area Plume Oct-92 Sep-95 Mar-97 Oct-99 Dec-00 Dec-01 Nov-02

August/ September
2006

March/ June
2008

May-10 Aug-10 Nov-10 Feb-11 Jun-11 Jan-12 Jun-12

October-
12

April -13

MW17 2 Bottom X X X X X X X X X X Not sampled
MW109 2 Bottom X X X X X X X X X X MW110 2 Bottom X X X Destroyed

MW112

Offsite North east Area 2

X X X

X X X X X X

Not sampled

MW113

Offsite North east Area 2

X X X X X X X X X Not sampled

MW121

Offsite Northeast Area 2

X X Destroyed

MW122

Offsite North Area 2

X X X X X X Not
Sampled

X X X

MW5 3 Bottom X X X X X X X X X Not sampled

MW12 3 Bottom X X X X X X X X X X Not sampled

MW13 3 Bottom X X X X X X X X X X Not sampled

MW14 3 Bottom X X X X X X X X X X Not sampled

MW18 3 Bottom X X X X X X X X X X Not sampled

Not sampled

Not sampled
X X X

38 | GHD | Report for Shell Company Australia - Environmental Audit Report, 22/15171/104595

Well ID Area Plume Oct-92 Sep-95 Mar-97 Oct-99 Dec-00 Dec-01 Nov-02

August/ September
2006

March/ June
2008

May-10 Aug-10 Nov-10 Feb-11 Jun-11 Jan-12 Jun-12

October-
12

April -13

MW204 2 X X MW205 2 X X MW206 2 Dry X MW207 2 X X

4.6 Adequacy of the assessor’s investigation program –
supporting documents

Details of the work undertaken by the assessor are included in their reports, which are
contained in Appendix C of this report. The following table outlines the relevant information and sections in the Assessor’s report:
Table 16 Assessor’s site assessment information

Assessment Details Assessor’s Reports (Appendix C of this report)

Site History ESA (Coffey 2006) ESA (URS 2008)
Site History Review and Summary of Previous Environmental Site
Assessments (URS 2010)

Environmental Validation Report (URS 2012)

Human Health and Environmental Risk Assessment (URS 2012)

Details of Sampling and
Analysis

Proposal for Targeted Source Investigation and Impact Removal and to Fill
Data Gaps for Validation Assessment (URS 2011)

ESA (Coffey 2006) ESA (URS 2008)
Environmental Validation Report (URS 2012)

GMEs (URS 2010 to 2012)

Field Observations ESA (Coffey 2006) ESA (URS 2008)
Environmental Validation Report (URS 2012)

GMEs (URS 2010 to 2012)

Borelogs ESA (Coffey 2006) ESA (URS 2008)
Environmental Validation Report (URS 2012)

Field Measurements ESA (Coffey 2006) ESA (URS 2008)
Environmental Validation Report (URS 2012)

GMEs (URS 2010 to 2012)

Site Plans ESA (Coffey 2006) ESA (URS 2008)
Environmental Validation Report (URS 2012)

Human Health and Environmental Risk Assessment (URS 2012)

Analytical Results
(Summary Tables)

ESA (Coffey 2006) ESA (URS 2008)
Environmental Validation Report (URS 2012)

GMEs (URS 2010 to 2012)

The analyte testing and laboratory analysis scheme as detailed in Sections 4.2 and 4.3 covered a range of analytes and sample depths. The auditor considers that the analyte testing program was commensurate with the site history, and was adequate for the purpose of the assessment.

5. Quality review of the site assessment
and auditor verification

5.1 Quality Control and Assurance

The auditor has undertaken a review of the Quality Assurance and Quality Control documentation presented by the assessor, and reviewed their procedures to verify the integrity of the data presented. A summary of this review is provided in Appendix F, along with individual report reviews.

For each phase of work the accuracy and integrity of the data information was reviewed in terms of the following aspects:

 Field Procedures

 NATA accreditation

 QC testing –Blind duplicates

 QC testing –Field Splits

 QC-Testing

 Laboratory Internal QC

 Rinsate Blanks

 Holding times

 Sample tracking

 Sample preservation and storage

 Calibration of Field Instruments

 Composite sampling method

 Volatile losses

 Data Transcription

 Laboratory detection limits

Overall the auditor was satisfied that the quality of the test results was adequate and the body of results reported was suitable for assessing the condition of soil and groundwater at the site.

5.2 Site visits by auditor

While undertaking the audit, the auditor and auditor’s assistants were involved in regular meetings, teleconferences and workshops involving the clients and assessors. The summary table below generally details the most significant activities undertaken by the auditor and the audit team, particularly site inspections and various meetings/workshops. Notes from site visits are provided in Appendix D.

Table 17 Summary of site visits and workshops by the auditor or auditor’s
assistants

Auditor and auditor’s assistants attended a site inspection of the Site and took photos. The site visit included discussion on the known history of the site including the works that URS undertook in 2008 and the plan for further works to commence in the future.

The site inspection was attended by URS, Shell and GHD.

Auditor and the auditor’s assistant attended teleconference to discuss the proposed plan forward. Requirements of the audit discussed including the needs for certainty that all sources had been removed, what impact remains on site
(soil and groundwater), and what can be remediated. The need for a construction management plan was discussed as was the need for GPR to assess potential UXO on the site.

The meeting was attended by URS, Shell and GHD.

Auditor and the auditor’s assistant attended site visit to observe the intrusive investigations and discuss remediation options and further site works. Observation was made of groundwater impact in open trenches, pipework present in subsoil in former tank bases, and odorous, stained soils present in source areas across the site. Photographs were taken.

The site inspection was attended by URS and GHD.

Auditor and the auditor’s assistant attended a teleconference to align all stakeholders’ expectations with the upcoming works and deliverables. Discussion of the GHD comments on the Validation Report, outcomes of the remediation activities on the site, requirement of the auditor to potentially undertake a site visit and do some test pitting on the site, the need for a meeting with Shell Real Estate team to discuss draft audit statements.

The meeting was attended by URS, Shell and GHD.

Auditor’s assistant attended site for collection of photos on and off site to provide context of works completed to date.

The site inspection was attended by GHD.

5.1 Conclusions on QA/QC

Overall the auditor was satisfied that the quality of the data provided was adequate and considers that the results reported were representative of the condition of soil and groundwater onsite at the locations sampled at the time of the assessments. The auditor concludes that the body of data can be used to draw conclusions with regard to the risks to beneficial uses arising from contamination, and suitability of management and mitigation measures to control these risks as may be required.

6. Pre-remediation site condition - soil

6.1 Soil assessment prior to site decommissioning

GTA (1995)

An Environmental Site Assessment (ESA) was prepared by Groundwater Technology Australia
Pty Ltd (GTA) in December 1995.

The ESA conducted by GTA included a background literature study, soil vapour survey at 87 locations, drilling of sixteen boreholes to depths of between 0.2 m and 1.2 m below ground level (bgl) and the installation of three groundwater monitoring wells to maximum depths of 7.8 m bgl.

The soil vapour survey indicated VOC concentrations ranging up to 1307 ppm at a depth of
0.5 m, and up to 1504 ppm, at a depth of 1.0 m. The soil vapour survey identified several areas of subsurface contamination which correlated with documented product losses at Tanks 1 and
15, or potential areas of concern such as the filling gantries, retention basins and the drum drilling shed.

Other areas of significant soil impacted included the lube oil tanks and the fire training area. Laboratory analysis of soil samples recorded concentrations of hydrocarbons above protection of sensitive use criteria at five locations, with concentrations predominantly in the C15-C28 range.

6.2 Soil assessment after decommissioning

Following site decommissioning, primary sources of contamination were removed from the site during March 2006. Primary sources included 19 aboveground storage tanks (ASTs), three underground storage tanks (USTs), associated pipework, mechanical workshop, drum shed, welding workshop, old rail siding, four oil traps (remain on site and have been emptied), potential dumping areas, fuel filling gantry, and tank waste sites including a leaded sludge site (north of Tanks 1 and 2) and a hydrocarbon dump (within the southern tank farm).

Phase 2 Coffey (2006)

In August and September 2006, Coffey conducted an environmental site assessment (ESA) at the site, with the objective of assessing the environmental status of soil and groundwater.

Nine soil bores and twenty three monitoring wells were drilled to target former infrastructure sites and areas that had anecdotal information provided to suggest that impact was likely to have occurred historically. Soil bores were drilled to between 2 and 5 mbgs and monitoring wells were drilled to between 5 and 10 mbgs. A total of 84 soil samples were collected and submitted for laboratory analysis. Fourteen of the 84 samples were collected to represent shallow/surface conditions (0.0-0.5 m bgl), 21 samples were collected at depth (3.0-8.0 m bgl) and 49 samples were collected from depths ranging from 0.6 m to 2.9 m bgl. Analyses were completed for:

 TPH

 BTEX

 Metals

 PAHs

 Phenols

Visual and olfactory observations and laboratory analytical results obtained during the initial investigations by Coffey (2006) indicated the presence of hydrocarbon-impacted soils at various locations across the site. The investigation found that concentrations of total recoverable hydrocarbons (TRH) in soil were elevated in areas directly associated with the former site infrastructure.

These sites included the following:

 Drum shed and pumpset (SB1, SB2 and MW3);

 Fuel filling gantry and nearby pumpset (SB3 and MW2);

 USTs located in the western corner of the site (MW1);

 ASTs Tank 3 (MW14), Tank 8 (MW13), Tank 11 (MW12), Tanks S5, S6 and S7 (MW5), Tank 10 (MW20), Tank 9 (MW22), Tank 15 (MW21), Tank S8 (MW17), Tanks S15 and S16 (MW16), Tank 14 (MW10), Tank 4 (MW11), Tank 1 (MW9) and Tank 2 (MW7);

 Retention basin/likely hydrocarbon dump where staining was observed (SB8);

 Oil traps (SB6 and SB7);

 Mechanical workshop and UST (SB4, SB5 and MW4);

 The southern tank farm and an area where black sludge and tar was likely buried in the north-eastern corner of the tank farm general site characterisation (MW18 and MW19;

 Leaded sludge which was likely buried in the northern portion of the site (SB9 and MW8);
and
 The northern tank farm and nearby retention basin/likely hydrocarbon dump (MW15). Elevated concentrations of TRH were recorded at Area 1 (MW2, MW3, MW6, SB1, SB3), Area
2 (MW7, MW11, MW17, MW16, SB8), Area 3 (MW14, MW18, SB6) and Area 4 (MW21, MW22). Elevated PAH was detected at MW2.

No heavy metals concentrations exceeded the screening levels (SL). Lead was detected below the NEPM HIL A at the majority of sites that were sampled and analysed.

The locations where visually identified hydrocarbon contamination was noted in the logs and the samples analysed that exceeded the EIL and HIL criteria for hydrocarbons are summarised in Table 1 of Appendix G and are shown on Figure 6 of the URS Validation report (URS 2013a).

The coinciding groundwater investigation is summarised in Section 7.1.

Phase 2 URS (2008)

To further characterise and delineate the extent of previously identified soil impacts, a Phase 2
ESA was conducted by URS in 2008. The soil investigation works included drilling and sampling of 59 soil bores, installation of an additional 22 groundwater monitoring wells and excavation of five test pits. A total of 299 soil samples were collected and submitted for laboratory analysis. Sample depths ranged from 0.5 to 9.5 m bgl. Analyses were completed for:

 TPH

 BTEX

 Metals

 PAHs

 Phenols

URS (2008) reported visual, olfactory and laboratory analytical results that concur with the findings and expanded upon the investigations undertaken by Coffey (2006). While concentrations in soil TRH was generally lower in the 2008 works, impacted soil was found in areas that were directly related to former infrastructure on the site. It is noted that soil bores were advanced using a pneumatic air hammer bit in hard rock during 2006 and 2008 works. As such, volatile COPCs may have been lost during drilling and sampling and may have been significantly under reported.

The site was assessed on the basis of sources of contamination in seven key zones:

 Northern tank farm (Area 2);

 Eastern tank farm (Area 4);

 Centre of site (Area 2/3);

 Southern tank farm (Area 3);

 Gantry (Area 1);

 Office (Area 1); and

 Workshop (Area 1).

Visually identified hydrocarbon contamination was noted in several bore and test pit logs included in the 2008 investigation. The majority of the visual contamination identified was located at depth and typically found within the range of depths that groundwater had been recorded. Table 2 of Appendix G summarises the locations where visually identified hydrocarbon contamination was identified and captured in the logs during the 2008 investigation and the samples analysed that exceeded the EIL and HIL criteria for hydrocarbons. The soil exceedences above adopted guidelines are shown on Figure 7 of the Validation Report (URS,
2013a).

Elevated concentrations of TRH were recorded at Area 1 (SB112-03), Area 2 (SB138-2.0, SB139-1.0, SB156-1.0, SB156-2.0 (as well as duplicate and triplicate samples), SB156-4.0), Area 3 (SB151-1.0, SB158-2.0), Area 4 (SMTP05-2.5, SB155-1.0, SB155-2.0), offsite (MW117-
4.0) and samples collected from the walls of the excavation sites of the triple interceptor traps (SMFS01-1.5E, SMFS01-1.5N, SMFS01-1.5S, SMFS01-1.5C, SMFS03-1.5C, SMFS03-2.0C). Total PAH was detected above the SLs in two samples, MW117-4.0 offsite to the north and SB156-2.0 (Area 2).

The following observations were noted by URS in relation to results that had exceeded the adopted screening levels:

 Shallow samples taken at SB109 and SB112 that were above the SLs suggest the surface covering of bitumen was the source of this impact.

 Detection of hydrocarbon fractions above SLs in samples SB151_1.0, SB158_2.0, SB138_2.0, SB139_1.0, SB155_1.0, SB155_2.0, SMTP05_1.0, SMFS01_1.5E, SMFS01_1.5N, SMFS01_1.5S, SMFS02_1.5C, SMFS03_1.5S, SMFS03_2.0C and SB125_4.0 are consistent with hydrocarbon fractions and additives found in Avgas, Jet fuel and SAP. These soil bores were located in the vicinity of former tanks T3 (SB151), T15 (SB155 and SMTP05), T2 (SB125), tanks and pump sets associated with S15 and S16 (SB138 and SB139) and product lines associated with T3, T8 and lines that ran to the former filling gantry (SB158).

 Detection of hydrocarbons and PAHs above SLs in samples from SB156 supports anecdotal evidence of a hydrocarbon dump in that area of the site.

 A historic product loss (noted by Coffey, 2006) in the northern corner of the site and
offsite migration from impact in the vicinity of former Tanks 1 and 2 were considered likely sources of hydrocarbon and PAH impact detected above SLs at off site well MW117 at
4 mBGL.

 Onsite soil impact had been observed in samples analysed from soil bores in close proximity to former site infrastructure. In particular T2 (Avgas), T15 (Automotive Gas Oil, AGO), T3 (Jet Fuel), S15 and S16 (Diesel/Jet Fuel Additive) and pipe work associated with these tanks.

Of the 299 soil samples that were analysed, no BTEX or phenols were detected above the screening levels (SLs) for all soil samples collected.

Heavy metals that exceeded the SLs included arsenic (10 samples), barium (2 samples), total chromium (4 samples), and vanadium (45 samples). Lead was not detected above the SL for any soil samples analysed. Table 3 of Appendix G details the samples analysed that exceeded the EIL and HIL criteria for metals.

6.2.1 Soil off-site investigation

Field investigations were carried out across the Site according to the phases of work described above. Groundwater monitoring bores were established off site to assess potential off site migration of contamination.

The following off-site groundwater bores were established during the ESA conducted by URS (2008).

 North - MW117, MW118, MW119, MW122

 Northeast - MW111, MW112, MW113, MW121

 East – MW120

 Southwest – MW108

 West – MW102, MW115

 Northwest – MW114

Soil samples were collected from these bores and assessed as part of the investigations. The only bore with soil concentrations which exceeded guidelines was MW117 off site to the north. Results from this bore exceeded guidelines for TPH C10-C36 and PAHs.

6.3 Soil vapour

Soil Vapour Survey URS (2008)

A soil gas survey was undertaken on 17 March 2008 which involved the installation of nine soil gas bores. One was installed to 0.9 m bgl, four were installed to 1.0 m bgl and four from 2.5 to
4.2 m bg. All soil bores were left for a minimum of seven days before sampling.

Soil gas sampling locations were placed on-site, with one located close to the former gantry (SGMW2), one near the drum shed (SGMW3), and the remainder around Tank 1 and Tank 2, where measureable PSH was detected in MW7 and MW15. The bores were located in areas considered to be representative of potential maximum concentrations, and to best represent the soil gas concentrations that might be present under future buildings constructed at the site. Nested vapour wells were installed to allow assessment of near source soil vapour concentrations, where groundwater standing water levels fluctuate significantly between seasons.

Helium leak detection tests were undertaken prior to sample all nine soil gas bores.

Samples were analysed for 2,2,4-trimethylpentane, benzene, ethyl benzene, propylbenzene, o- xylene, cumene, chloromethane, chloroethane, acetone, carbon disulfide, 2-butanone, 2- propanol, chloroform, freons, ethanol, bromodichloromethane, heptane, hexane and cyclohexane. SGMW2B (deeper), SGMW7A & B could not be sampled as they were below the water table and water was present in the sampling line.

The soil gas data collected at the site included low but positive concentrations of a range of chemicals identified as potential COPC based on the historical site usage, as well as a range of other chemicals reported at low concentrations.

SGMW2 and its field duplicate (MAQC102) reported results above the adopted (modified) screening levels for benzene and hexane. Benzene concentrations above the adopted IL were detected in groundwater sample MW2 located adjacent to SGMW2. TPH C6-C9 was also detected in groundwater sample MW2; however concentrations did not exceed adopted ILs.

Results are included in Appendix J of URS 2008, included as Appendix C of this report.

Soil Vapour Survey URS (2010)

Soil vapour sampling was also conducted in May 2010 by URS. The results are summarised in and discussed in Appendix D.4 and E.4 of the HERA (URS, 2013c), included as Appendix C of this report, but had not been reported separately prior to this.

No benzene was detected in the 2010 sampling event. Hexane was detected in SGMW2A and its duplicate, however concentrations did not exceed the adopted investigation levels. In the sample from the adjacent, deeper well SGMW2B no hexane was detected.

The only hydrocarbon identified above LOR in the vapour samples was 2,2,4-trimethylpentane (TMP). The reported concentrations were approximately 50 times higher than the adopted HSL screening value for C6-C10 aliphatic TPH.

Trimethylpentane

Trimethylpentane (TMP) was reported in soil vapour results in Area 1 in both May 2008 and May 2010. At the time of the 2008 report, the TMP results were not compared to guidelines as no specific guidelines are available. URS noted that as TMP falls within the TRH C6 -C10 fraction, they have been assessed against the guideline for this fraction. The most recent data (May 2010) shows that greater than 99% of the measured vapour phase hydrocarbons comprised the fuel additive TMP.

In Appendix D of the HERA (URS, 2013c), URS compare the TMP results to an adopted guideline of 6,080,000 µg/m3 as an initial screen for TMP in soil vapour. Soil gas measurements from soil bore SGMW2A collected from the depth range 0.7 to 1.9 mBGL (and its duplicate samples) slightly exceeded the adopted guideline in both 2008 and 2010. The use of this
guideline is discussed further in Section 3.5.4, of the HERA (URS, 2013c).

A preliminary assessment of the potential risks associated with TMP vapours was conducted by URS in the HERA report (URS, 2013c). Soil and groundwater results were also assessed for TMP, and results are discussed in Sections 6.5.8 and 10.6.7 of this report.

6.4 Validation report, URS 2013

6.4.1 Test pits

Test pits were excavated with the aim to delineate and excavate visually hydrocarbon impacted or odorous material. Test pits were typically excavated to the top of the bedrock (where refusal occurred) or to intersection with the dry season water table (approximately 3-4 mBGL).

It is noted that URS undertook test pit investigations in conjunction with remediation works, however the test pits give an indication of pre-remediation site condition and so are summarised in this section. Details of the work undertaken and results are provided in the URS Validation report (URS, 2013a). During test pitting works, any remaining concrete, asphalt, steel and unremoved pipework was removed from the site and disposed of offsite to a recycling facility.

During the 2011 test pit work, 82 test pit locations and 29 road base test pits were excavated, and over 300 soil samples were collected from depths between 0.1 m and 4 m from across the site and submitted for laboratory analysis. The investigations and results are summarized below for each area and a Table of exceedances is presented as Table 18 below. Further detail on the test pit program and field observations are provided in Section 3.4 of validation report and the results of the investigations are discussed further in Section 5.3 of the URS validation report (URS, 2013a). Exceedances are indicated on Figure 5.

Area 1

Twenty-five test pit locations were sampled from Area 1. Eleven locations reported exceedances of screening levels. Exceedances were noted for TPH C6-C9, TPH C10-C36, and lead.

Exceedances were in locations in close proximity to former infrastructure, including:

 The fuel filling gantry (TP02_01 and TP02_03);

 The former drum shed (TP03_02, TP03_03, TP03_04, TP03_05 and TP03_07);

 Mechanical workshop (TP07_01);

 Former fuel filling shed (pre 1981) (TP15_01);

 Former stormwater trench slab & guttering(TP31_01); and

 Former fuel line (TP34_01).

The auditor notes that four of these locations were vertically delineated, but seven of them were not, and the deepest sample had exceedances. Locations TP02_03 TP03_07, TP_031, TP15_01 and TP34_01 were excavated until refusal occurred on hard rock and were not able to be delineated further. TP03_03 and TP03_04 were later excavated and removed (refer to Section 6.4.2). Residual impacts are discussed in Section 10.

Twenty road base samples, collected from surface following bitumen removal were analysed, and no exceedances were reported. Rock outcropped immediately beneath the bitumen, thus samples were collected from unconsolidated material on top of rock.

Area 2

Thirty test pit locations were sampled from Area 2. Fourteen locations reported exceedances of screening levels. Exceedances were noted for TPH C6-C9, TPH C10-C36, and ethylbenzene.

Four of the locations were delineated vertically and deeper samples were obtained with no exceedances noted, but the rest were not delineated. The deepest exceedance was at 4 m. Apart from TP16, these locations were all later excavated as part of remediation work, refer to Section 8.

Exceedances were noted at the following locations:

 TP16 – test pit in the vicinity of the rail siding/former product line. The sample at 0.5 m exceeded investigation levels for TPH C10-C36. At 0.5 m a section of the former product line was located and removed, no fuel was present in the line.

 TP17 – test pits adjacent to the area of concern for potential buried leaded sludge from base of ASTs. TPH C6-C9 above investigation levels was observed at TP17_01 at 2-3 m but concentrations were below investigation levels at 4 m. TP17_02 exceeded investigation levels for TPH C6-C9 at 4 m.

 TP18 – Test pits located within the northern retention basin, including areas of former product lines and an exchange pit, down gradient of the former ship’s manifold. Impacts observed at four locations (TP18_01 to TP18_04) for TPH C6-C9, TPH C10-C36, and ethylbenzene at depths ranging from 0.5 to 4 m.

 TP19 – Test pits located throughout the filled in area between ASTs 1 and 2, including areas of former product lines. Investigation levels exceeded for TPH C6-C9 and TPH C10- C36 at depths ranging from 2 top 4 m.

 TP20 – test pit above the former oil trap number 12. Concentrations of TPH C6-C9 and
TPH C10-C36 exceeded investigation levels at 3 m.

 TP21 – test pit located within footprint of former ship’s manifold and Slops ASTs S15 and
S16. Concentrations of TPH C6-C9 and TPH C10-C36 exceeded investigation levels at 3 m.

Area 3

Thirteen test pit locations were sampled from Area 3. Six locations reported exceedances for
TPH C6-C9 and TPH C10-C36. The auditor notes that all six locations were vertically delineated.

 TP24B (comprised four locations, TP24B-01 to 04) – test pits located within the central retention basin, including areas of concern for potential surface bitumen slops and product lines. Hydrocarbon impact was noted in samples from surface to 3 m depth, however samples taken from 4 m reported hydrocarbon concentrations less than investigation levels.

 TP32 – test pit was located within the central retention basin, in the vicinity of former product lines. Sample taken at 2 m exceeded investigation levels for TPH C6 -C9 and TPH C10 -C36. However the sample taken at 2.8 m was below investigation levels.

 TP33 – test pit was located within the central retention basin, in the vicinity of former product lines, down gradient of AST11. Sample at 1 m exceeded investigation levels for TPH C10 -C36. Sample taken from 2-4 m was below investigation levels.

Area 4

Three former ASTs: AST9 (jet fuel/gas oil), AST10 (jet fuel) and AST15 (gas oil, automotive gas oil) were located in Area 4. Seven test pit locations were advanced in Area 4. Exceedances for TPH C10-C36 were noted in three locations. One of the three locations was vertically delineated, the other two had exceedances at the maximum depth investigated.

 TP26 – test pit was located in the vicinity of former product pipelines and concrete drain.
TPH C10-C36 concentrations above the screening levels were observed at 0.5 and 2 m.

 TP39 – test pit located in the vicinity of former product pipelines along north eastern boundary fence. TPH C10-C36 concentration above the screening levels was observed at
0.5, and was vertically delineated, with samples at 1 and 2 m less than detect.

 TP40 – test pit located adjacent to AST15 and the fill and bund wall. TPH C10-C36
concentration above the screening levels was observed at 1.7 m.

Area 5

There were no guideline exceedances in the seven test pits sampled from Area 5. PFOS concentrations were detected at near surface samples (<0.5 m) across Area 5 in seven samples of 14 samples analysed. No samples were collected deeper than 0.5 m due to shallow bedrock. The concentrations (ranging from 0.0008 – 0.012 mg/kg) did not exceed the MPCA guideline for PFOS of 14 mg/kg.

A summary table of exceedances from all areas is included in Table 18.

Table 18 URS 2011 Test pit TPH, BTEX & Lead result exceedences for
NEPM EIL & HIL

*sample labelled 1.0 m depth however likely to be mislabelled and actually 1.7 m depth due to duplicate results for 1.7 m being similar.

6.4.2 Area 1 additional investigation

In order to delineate the identified impact in the vicinity of the former fuel gantry and drum shed, in Area 1, URS undertook an additional push tube investigation in September 2012. As part of this investigation 17 push tubes were advanced at locations of previously identified soil impact. The 17 push tubes were advanced to the top of the bedrock (where refusal occurred).

Push tubes were advanced at locations of previously identified impact and delineated laterally until field indications of potential impact (PID, odour and discolouration) were no longer identified. An area of hydrocarbon impacted material approximately 20 m by 20 m was identified by PID, odour and discolouration in shallow soils during completion of push tubes in the vicinity of BP03-1. Analytical results of selected soil samples routinely exceeded the adopted SILs and SSTLs, and it was considered appropriate to dispose of this material off-site. The subsequent off-site disposal and validation of this area is detailed in Section 9.4 and 10.2.1 of this report.

6.5 Other contamination

6.5.1 Uncontrolled fill

Following the bombing of Darwin in 1942 and Cyclone Tracy in 1974 some areas close to the Darwin CBD were filled with debris including building materials or refuse. It was possible that areas of the site may have been filled using this material, posing a potential chemical and aesthetic contamination risk. The potential extent and nature of uncontrolled fill was investigated by test pitting. There was no indication of uncontrolled filling by debris of this nature being encountered during test pitting works across the Site.

Uncontrolled filling by imported fill was noted by the assessor to occur in Areas 1, 2, 3 and 4 during the various stages of works. The origin of this material is unknown. The fill material could have been sourced on site as cut and fill material or imported onto the site from another source. Fill material, imported or cut from the site, would have been required during leveling and construction earthworks for retention basins and bunds.

Data collected by the assessor and presented in the log sheets (Coffey 2006, URS 2008, URS
2012) identified fill material present as a base material for former ASTs (Areas 2, 3 and 4) and as backfill for former USTs (Area 1). The depth of the fill was approximately 0.5 m at former AST locations and up to 4 m at the former UST locations. Fill in areas where bund walls and AST bases were located (Areas 2, 3 and 4), minor filling/sub-base (<0.2 m) in Area 1 below former bitumen hardstand.

The assessor calculated inferred unconsolidated material depth (Figure 20, Validation Report URS 2012) across the site using data from the remediation and validation works. The data indicates that areas on the lower portion of the site generally corresponded with the main areas of fill.

Chemical analysis undertaken by the assessor (URS 2012) indicated that aldrin and dieldren were present in concentrations below the NEPM A residential guidelines in Areas 1 and 2.
These chemicals are common in historically used insecticides and are not considered a concern
to human health at the concentrations recorded on the site.

6.5.2 Acid sulphate soils

Acid sulphate soil analysis has not been included in the scope of the audit or assessment work. Potential acid sulphate soils are not considered a risk at the site as the majority of the site consists of rock outcrop and no marine sediments were encountered in low lying areas of the site during previous works.

6.5.3 Asbestos

Removal and demolition

In March 2009, McMahon Services Australia (NT) Pty Ltd conducted demolition and removal of asbestos containing material (ACM) at the former main office and toilet block. Asbestos containing material was removed to Shoal Bay Waste Disposal Facility in accordance with relevant NT regulatory requirements.

Monitoring and verification was undertaken by AEC Environmental during and at the completion of works. AEC conducted air monitoring and visual inspection and confirmed that asbestos removal had been undertaken in accordance with the NOHSC Code of Practice for the Safe Removal of Asbestos. All accessible surfaces were found to be clear of ACM debris and no fibres were detected during air monitoring.

The McMahon services report is included in Appendix L of the URS Validation report (URS,
2013a), which is included as Appendix C of this report.

Validation

During the Site works undertaken in 2011, fragments of suspected asbestos containing material were observed and collected in the immediate vicinity of the former main office (Area 1) prior to demolition of the remaining main office and amenities block foundation slabs. A representative sample of the suspected ACM was sent to ALS. The laboratory report stated that the sample consisted of fibro plaster cement material and no asbestos was detected.

A visual assessment was also undertaken following slab removal. No further fragments of suspected ACM were observed.

Visual observation for the presence or absence of ACM was undertaken across other areas of the site at the time of site surface vegetation removal and observation. There was no evidence of fragments of asbestos containing material observed.

A potential bonded ACM stormwater pipe was noted beneath the bitumen road that formed the boundary between Areas 2 and 3 in the vicinity of the stormwater drain. The pipe was removed for off-site disposal at Shoal Bay. No further potential ACM was encountered during site works.

Based on review of historical site plans, URS concluded that structures containing ACM were located in Area 1. As much of the site surface consisted of sealed surfaces, rock outcrop or poorly developed soil profile, it was not considered necessary to analyse soils across the site for asbestos.

6.5.4 UXO

An unexploded ordnance (UXO) risk assessment was undertaken by G-Tek (24 February 2012). A copy of the report is included in Appendix H of the Validation Report, (URS, 2013a), a copy of which is included as Appendix C of this report.

The key findings were that no records reviewed indicated that the Site had been targeted for bombing or used by Allied forces in the Defence of Darwin. The field survey conducted found no evidence that explosive ordnance had impacted the site, but noted that the effectiveness of the survey was hampered by large volumes of metallic infrastructure and scrap still within the site.

With mitigation measures recommended by G-Tek, the risk rating for the site was low.

It is noted that the site has also undergone extensive intrusive environmental investigations including test pits, soil bores, surface scraping and broad scale excavation over areas of unconsolidated material and outcropping bedrock. Intrusive environmental investigations have been undertaken during 2006, 2008 and 2011. At no time during these works were indications of suspected EO impact or UXOs identified.

6.5.5 Pesticides

Organochlorine (OC) and organophosphorous (OP) pesticides and arsenic were identified as potentially having been used on site as weed and/or pest control across the site. Samples were submitted for testing for OC and OP pesticides and arsenic during 2011 test pitting work.

Trace concentrations of organochlorine pesticides OCPs (aldrin and dieldrin) were detected widely in samples taken across the Site, well below residential guidelines (NEPM A 10 mg/kg). Organophosphorous pesticides (OPPs) were not detected greater than LOR in samples taken across the Site. Arsenic was not detected at concentrations exceeding the adopted IL in samples taken from across the Site.

6.5.6 PCBs

A small electrical substation is located in an easement to the western corner of the Site (Area
1). An off-site diesel engineering firm, panel shop and several mechanical workshops operated in the vicinity of the southern corner of the Site (Area 5). No indication of staining was observed in the vicinity of the substation or the workshop buildings. No analytical results were reported greater than LOR for PCBs across the Site.

6.5.7 Perfluorooctane Sulphonate (PFOS)

Sampling for PFOS in soil was conducted by URS in 2011 targeting the fire training area (Area
5) on the basis that use of surfactants in this area would have been most frequent over the life of the site. In the absence of Australian guidelines, URS adopted the Minnesota Pollution Control Agency (MPCA) (2009), Tier 2 Industrial Soil Reference Value Thresholds for PFOS/PFOA, Draft Guidelines: Risk-based Guidance for the Soil-Human Health Pathway, June 2009 for screening purposes.

In soil, concentrations above LOR were identified in seven of 14 samples, with a maximum concentration of 0.012 mg/kg and a 95%UCL of the mean of 0.0039 mg/kg. These concentrations were 2-3 orders of magnitude lower than the US EPA Region 4 Soil screening criteria for PFOS of 6 mg/kg. PFOA concentrations were below laboratory detection limits. URS concluded that the soil results suggested the concentrations on site should not present a significant health risk. However, due to the highly mobile nature of PFOS in groundwater, sampling for PFOS and PFOA in groundwater was undertaken in 2013 at the request of the Auditor. The findings are discussed in Section 10.6.6.

6.5.8 Trimethylpentane

Following detection of TMP in soil vapour, it was considered that further investigation of potential remnant TMP in the top 1 m of unconsolidated material in the gantry and drum shed area was necessary. As part of the push tube investigation in Area 1 in September to November
2012, the investigation also included analysis for TMP in soil. Analytical results for nine samples that reported concentrations of TPH above the LOR from this area were examined by the laboratory for indication of TMP. The analytical results suggest that TMP is present in three samples obtained from unconsolidated material in the vicinity of the former drum shed and filling gantry (BP03-1). This area was later excavated and the material disposed of.

In addition, the laboratory re-examined previously collected soil data collected from November
2011 and found that Test Pit TP19a, located a few metres north-west of MW07 (Area 2), indicated that TMP was the dominant volatile aliphatic hydrocarbon species present in soil samples collected at 3, 4 and 5 mBGL. TMP was also indicated to be a major component of the volatile aliphatic hydrocarbons present at Test Pits TP19b and TP17 located west and north- west of TP19a. This area was later excavated.

Analytical screening results for 2,2,4-Trimethylpentane in soil and groundwater are presented in
Table 10 of Addendum A of the Validation report (URS 2013a).

7. Pre-remediation site condition -
Groundwater

7.1 Historical groundwater monitoring prior to site decommissioning

Groundwater sampling was undertaken on the site on an annual basis from 2000 up until 2002. Of four groundwater bores that were installed in 1995 only two were sampled on a regular basis. No phase separated hydrocarbon (PSH) was reported during this time. Hydrocarbons were reported at MB2 in 2000, and polycyclic aromatic hydrocarbons (PAH) and naphthalene were detected below adopted screening levels in 2001. The groundwater monitoring event
(GME) in 2002 concluded that there were insufficient monitoring wells to determine hydrocarbon trends for the entire site.

A number of other investigation reports were prepared for the site which have not been provided to the Auditor for review. At some time prior to 1999 monitoring wells MC1 and MB1 were lost, possibly destroyed.

A summary of the GMEs is provided in Table 19 below.

Table 19 Summary of GMEs prior to decommissioning

Event Scope Overview of investigation and findings
Phase II ESA, Groundwater
Technology, 1995 Three groundwater monitoring wells installed at the Site GTA stated that the low permeability of soils underlying the site and the slow rate of groundwater flow would be unlikely to result in significant offsite migration of dissolved contaminants. Stormwater drain running along the eastern boundary of the site was considered the most likely avenue for off-site migration of hydrocarbons. No significant concentrations of dissolved hydrocarbons were identified in the three groundwater monitoring wells installed at the Site. No PSH was identified at any groundwater monitoring well location.
Groundwater Monitoring Event, IT Environmental, December 2000 Gauging and groundwater sampling at two groundwater monitoring wells MB2 (T) and MB3 (T)
Groundwater standing water levels (SWLs) ranged from 3.193 m bgl to 3.83 m bgl. SWLs varied considerably before and after purging. The two wells sampled had yields of less than three litres per minute. Depth to groundwater appears to have fluctuated over time with the water table in the unconfined aquifer falling by at least 0.4 m/year.
TPH C6-C9, BTEX, and lead were reported below laboratory detection levels. Detectable concentrations of C10-C14 (140 µg/L), C15-C28 (300 µg/L) and C29-C36 (100 µg/L) were reported at one well. PSH was not detected in any of the groundwater monitoring wells gauged.
Relatively high post purge concentrations of dissolved oxygen (DO) (3.93 to 4.29 mg/L) and high redox readings (202 to 219 mV) suggest oxidising conditions, but there is little difference between the two wells and evidence of aerobic degradation is limited. Elevated ferrous iron concentrations and depleted nitrate concentrations in the impacted well MB2 (T) compared to the less impacted well MB3 (T) indicates anoxic/anaerobic biodegradation of hydrocarbons. Presence of heterotrophic and contaminant utilising bacteria apparent in both wells indicates potential for microbial degradation of hydrocarbons.

Groundwater Monitoring Event, IT Environmental, December 2001 Gauging and groundwater sampling at two groundwater monitoring wells MB2 (T) and MB3 (T)
Groundwater standing water levels (SWLs) ranged from 3.26 m bgl to 3.87 m. SWLs varied considerably before and after purging. Gauging was conducted during the wet season and was expected to be near the maximum depths recorded. Trends reported for the groundwater gauging data were generally consistent and within the same range of the previous GME. Seepage velocity was estimated to be 0.3 to 0.5 m/yr.
Polycyclic aromatic hydrocarbons (PAH) were included in the analytical suite for this round of sampling. TPH C10-C36 (740 µg/L) and naphthalene (1 µg/L) were detected at MB2. All other analytical results were below investigation levels. No PSH was detected in any of the groundwater monitoring wells gauged.
DO concentrations are similar to those recorded for the last GME. The post purge DO measurements (3.44 to 4.30 mg/L) indicated aerobic conditions. Post purge redox readings (84 to 111mV) indicated conditions were mildly oxidising. The results provide clear evidence of natural attenuation occurring.
Groundwater was fresh with the field TDS range between 39 mg/L and 41 mg/L and the laboratory TDS 230 mg/L and 530 mg/L. pH was slightly acidic ranging from 5.34 to 5.72.

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Event Scope Overview of investigation and findings

Groundwater Monitoring Event, IT Environmental, November 2002

Gauging and groundwater sampling at one groundwater monitoring well MB3 (T)
(MB2 had been lost/destroyed during the previous season)

The groundwater standing water level (SWL) in the well MB3 was 4.65 m bgl, or
14.316 mAHD. The groundwater level was within the screened interval. Gauging was conducted at the start of the wet season. Depths to SWL would be near the maximum depths
recorded at the end of the dry season. The depth to SWL in November 2002 was 0.693 m
greater than previous low water table measurement (October 1999).
All analyte concentrations for contaminants of concern were below the limit of reporting. There was no PSH detected.
Field groundwater quality data was generally consistent and within the range of previous measurements. The exception was electrical conductivity (EC) and TDS which were at their historical low.

7.2 Groundwater investigation after site decommissioning

Twenty three groundwater monitoring wells were established on the site by Coffey in 2006 following the closure of the site in 2005. An additional 22 groundwater monitoring wells were established in 2008 by URS. In addition to the groundwater monitoring carried out during the
2008 ESA, URS was commissioned to undertake quarterly groundwater monitoring from May
2010 to January 2012.

A summary of the GMEs is provided in Table 20 below and findings of the quarterly GMEs are described in the Sections below.

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Table 20 Summary of GMEs after decommissioning

Event Scope Analysis Overview

Phase 2 Coffey
(2006)
23 groundwater monitoring wells were installed at the Site as part of Coffey Phase
2 ESA works
TRH, BTEX, metals, PAHs and phenolic compounds.
Groundwater levels were identified at depths of 1.467 to 9.890 m bgs, or
4.318 to 14.108 m AHD. The groundwater was identified to be in an east- north easterly direction, with average hydraulic gradient of 0.038 with seepage velocity estimated to be 0.256 to 0.450 m/year. An additional 23 groundwater monitoring wells were established on the site in 2006 following the closure of the site in 2005. The sampling returned results with elevated petroleum hydrocarbon concentrations exceeding the effective solubility of TRH in water (with PSH likely present) at MW7, MW9, MW11, MW13 and MW15 (PSH was not observed during sampling). Dissolved phase petroleum hydrocarbon impact extended across the site with elevated concentrations of BTEX, Naphthalene or lead in 21 of the 23 on-site monitoring wells.

Based on the results, it was concluded that there were several sources of petroleum hydrocarbon impact across the site. TRH and/or BTEX concentrations at MW2, MW7, MW9, MW11, MW13 and MW15 indicated six main located sources – however elevated concentrations were identified at all locations.

Phase 2 URS (2008)
22 additional groundwater monitoring wells were installed at the Site by URS as part of Phase 2 ESA works.
TPH, BTEX, metals, PAHs and phenols

The objective was to further characterise and delineate the lateral extent of the previously identified groundwater hydrocarbon impacts at the site and to identify potential human health and environmental risks.

The results of the study show the presence of heavy metals in soil and groundwater. Exceedances of the adopted groundwater investigation levels were identified for arsenic, barium, chromium, copper, lead, mercury, nickel and zinc in groundwater. Measureable PSH was noted in MW7 and MW15.

It was noted that a number of potential on-site contaminant sources have been identified which have not been assessed. Only petroleum hydrocarbon related impacts were assessed at this stage.

GME URS (May
2010)
43 monitoring wells were gauged and sampled in April
2010

MW111 and MW114 (off-site wells) had been destroyed.
Type I (TPH C6 -C36 , BTEX and Pb) and Type II (PAH and Phenols) analysis and selected groundwater samples for Shell Type III (OCP/OPP and PCB).
The groundwater elevations onsite ranged from 6.88 m to 16.00 m AHD, and off site from 3.8 m to 15.6 m AHD, with the interpreted direction of the groundwater flow was to the north-east. No PSH was detected within any of the wells during the gauging round, although sheen was noted in MW02, MW07, MW13 and MW15.

Groundwater samples were collected via low flow method (with the exception of MW121).

During purging, hydrocarbon odours were noted at 9 onsite wells (Area 1: MW01 to MW03; Area 2: MW07, MW09, MW11and MW15; Area 3: MW13; Area 4: MW21) and 2 offsite wells (MW117 and MW119).

Event Scope Analysis Overview

Concentrations of lead and naphthalene were detected at levels greater than the adopted groundwater investigation levels within Areas 1 and 2. The exceedences were reported as: MW07 located in Area 2 within the former footprint of an AST labelled Tank 2 (Lead: 0.016 mg/L); MW103 located in Area 1 to the east of the former fuel filling gantry (Lead: 0.006mg/L); MW15 located in Area 2 (Naphthalene: 93.9ug/L and a blind duplicate: 187ug/L).

For the May 2010 GME, reported concentrations of the petroleum related contaminants of potential concern decreased significantly in comparison to the investigation carried out in 2006 (Coffey). In comparison to the 2008
GME rounds (April, May and June 2008), it was observed that the concentrations of the contaminants of potential concern either decreased or
increased slightly. A summary of the dissolved phase contaminants detected is provided in Section 7.3 below.

GME URS (August
2010)
40 monitoring wells were gauged and sampled.

MW121 had been destroyed and MW06 and MW10 could not be gauged due to blockages.

Type I analysis (Pb, TPH and BTEX) and Type II analysis (PAH and Phenolic Compounds), and select samples for Shell Type III analysis (OCP/OPP) and Shell Type V analysis (Natural Attenuation Parameters).

The groundwater elevations onsite ranged from 3.95 m to 14.31 m AHD, and off site from 3.05 m to 13.00 m AHD, with the interpreted direction of the groundwater flow was to the North-east. Groundwater samples were collected via low flow method (with the exception of MW09 where a grab sample was collected due to insufficient water).No PSH was detected within any of the wells during the gauging round. There were three wells (MW02, MW11 and MW110) where sheen was noted during sampling. A hydrocarbon odour was observed at monitoring wells MW02, MW03, MW07, MW11, MW13, MW14, MW15, MW18, MW110 and MW119.

Concentrations of Benzene and Lead were detected at levels greater than the adopted investigation levels within Areas 1 and 2, and at a location immediately outside of the north-eastern boundary of Area 1. The exceedences were reported as: MW07 located in Area 2 within the former footprint of an AST 2 (Benzene: 1840 ug/L and Lead: 0.016 mg/L); a blind of MW11 located in Area 2 within the former footprint of AST4 (Lead: 0.018 mg/L); MW103 located in Area 1 to the east of the former fuel filling gantry (Lead: 0.005 mg/L) and MW115 located offsite adjacent to the former workshop in Area 1 (Lead: 0.004mg/L).

Generally, it was observed that the concentrations of the contaminants of potential concern either stabilised and were consistent with the historical results or a decreasing trend was observed since the investigations carried out since 2006 (Coffey). The exception was a slight increase observed in the TPH and Lead values at MW11 in Area 2 compared to the May 2010 and
2008 investigation. However, the results were still significantly less than the
2006 investigation results.

A summary of the dissolved phase contaminants detected is provided in
Section 7.3 below.

Event Scope Analysis Overview

GME URS (November 2010)
40 monitoring wells were gauged and 39 monitoring wells were sampled.

MW110 had been destroyed and MW115 was inaccessible and so could not be gauged.

MW104 was accessible, however it was not sampled due to insufficient water quantities.
Type I analysis (Pb, TPH and BTEX) and Type II analysis (PAH and Phenolic Compounds), and select samples for Shell Type V analysis (Natural Attenuation Parameters).
The groundwater elevations onsite ranged from 6.3 m to 15.44 m AHD, and off site from 3.46 m to 13.85 m AHD, with the interpreted direction of the groundwater flow was to the North-east. No PSH was detected within any of the wells during the gauging round. All wells sampled by low flow except MW120 and MW19 where a grab sample was taken due to insufficient groundwater. MW2, MW3, MW5, MW7, MW9, MW11, MW15, and MW21 had petroleum hydrocarbon odours throughout purging. Sheen was observed on purge water from MW5, MW7, MW11, MW15, and MW21. In addition to the reported hydrocarbon odours, H2S odours were noted at two onsite wells (MW13 and MW109) and 3 offsite wells (MW113, MW117 and MW118).

Elevated TDS values were noted in comparison to the historical readings at
MW109 and MW122, during the August 2010 GME, with results of
19,045 mg/L and 42,705 mg/L respectively. However they were not reported during this monitoring event. The August 2010 results were significantly greater than historical results. It is considered that these results were
anomalous.

Concentrations of Benzene, Lead and Naphthalene were detected at levels greater than the adopted groundwater investigation levels within Areas 1 and
2. The exceedences were reported as: MW07 located in Area 2 within the
former footprint of AST 2 (Benzene: 1300 ug/L and Lead: 0.007 mg/L); MW03 located adjacent to the former oil line leading to the fuel filling gantry in Area 2 (naphthalene: 18.9 ug/L); and MW10 located in Area 2 within the former footprint of AST 14 (Lead: 0.006 mg/L).

For the November 2010 GME, reported concentrations of the petroleum related contaminants of potential concern decreased significantly in comparison to the investigation carried out in 2006 (Coffey). In comparison to the quarterly monitoring rounds commenced since May 2010, generally, it
was observed that the concentrations of the contaminants of potential concern either stabilised or increased slightly but still consistent with the
historical results. Some fluctuations have been observed which may have
been influenced by seasonal effects where rising groundwater levels may mobilise hydrocarbons adsorbed to the soils within the smear zone, into the
dissolved phase.

A summary of the dissolved phase contaminants detected is provided in
Section 7.3 below.

GME URS (February 2011)
37 monitoring wells were sampled.

As well as those noted above, MW06 and MW10 were blocked and MW20, MW22 and MW116 were reported to be inaccessible
Type I analysis (Pb, TPH (TRH rather than TPH for triplicate samples) and BTEX) and Type II analysis (PAH and Phenolic Compounds), and select samples for Shell Type V analysis (Natural Attenuation
The groundwater elevations onsite ranged from 7.37 m to 17.32 m AHD, and off site from 4.2 m to 16.87 m AHD, with the interpreted direction of the groundwater flow was to the North-east. No PSH was detected within any of the wells during the gauging round. All wells sampled by low flow except MW19 and MW104 where grab samples were taken due to insufficient groundwater.

Event Scope Analysis Overview
due to flooding. Parameters).
MW03, MW10, and MW11 had an H2S odour throughout purging. MW02, MW05, MW07, MW11, MW15 and MW117 had petroleum hydrocarbon odours throughout purging. Sheen was observed on purge water from MW02.

Concentrations of Benzene and Lead were detected at levels greater than the adopted groundwater investigation levels within Areas 1 and 2. The exceedences were reported as: MW07 located in Area 2 within the former footprint of AST2 (benzene: 4030 ug/L and Lead: 0.021 mg/L) and MW103 located in Area 1 to the east of the former fuel filling gantry
(Lead: 0.005 mg/L).

For the February 2011 GME, reported concentrations of the petroleum related contaminants of potential concern decreased significantly in comparison to
the investigation carried out in 2006 (Coffey). In comparison to the quarterly monitoring rounds commenced since May 2010, generally, it was observed in some locations that the concentrations of the contaminants of potential concern have increased slightly while in other locations concentrations
decreased slightly.

A summary of the dissolved phase contaminants detected is provided in
Section 7.3 below.

GME URS (June
2011)
40 monitoring wells were gauged and 38 monitoring wells were sampled.

MW05 and MW09 were not sampled due to health and safety hazards for field staff within the area.
Type I analysis (Pb, TPH and BTEX) and Type II analysis (PAH and Phenolic Compounds), and select samples for Shell Type V analysis (Natural Attenuation Parameters) and VOCs (1 primary).

The groundwater elevations onsite ranged from 5.52 m to 15.17 m AHD, and off site from 3.68 m to 14.65 m AHD, with the interpreted direction of the groundwater flow was to the North-east. No PSH was detected within any of the wells during the gauging round. During sampling, sheen was noted at MW11. Groundwater samples were collected via low flow method (with the exception of MW21 and MW104 where grab samples were collected due to insufficient water).

During purging, hydrocarbon odours were noted at wells MW02, MW03, MW07, MW11, MW15, MW18 and MW117. In addition to the reported hydrocarbon odours, H2S odours were noted at 5 onsite wells (Area 2: MW10 and MW16; Area 3: MW18; Area 4: MW21; Area 5: MW105) and one offsite well (MW118).

Concentrations of Benzene and Lead were detected at levels greater than the adopted groundwater investigation levels within Areas 1 and 2. The exceedences were reported as: MW07 located in Area 2 within the former footprint of AST 2 (benzene: 7610ug/L and Lead: 0.056 mg/L) and MW103 located in Area 1 to the east of the former fuel filling gantry
(Lead: 0.005 mg/L).

Event Scope Analysis Overview
The overall trend for reported concentrations of the petroleum related contaminants of potential concern show decreasing concentration in comparison to the investigation carried out in 2006 (Coffey). However, it was observed that a slight increase in concentrations was observed across the monitoring network while comparing the Feb. 2011 GME with the June 2011
GME. URS noted in the report, “the 2010/2011 wet season was one of the wettest on record (2054 mm total during December 2010, January 2011 and
February 2011 [Bureau of Meteorology]). Based on a review of the climatic data, it is possible that elevated groundwater levels may have re-mobilised adsorbed phase hydrocarbons within the smear zone following this period.”

A summary of the dissolved phase contaminants detected is provided in
Section 7.3 below.

7.3 Quarterly groundwater monitoring events 2010-2012

Scope of monitoring program

The scope of the quarterly groundwater monitoring events was to investigate the nature and extent of petroleum hydrocarbon impacts to groundwater, also considering the impact associated with seasonal fluctuations (dry/wet season). Evidence of natural attenuation occurring at the site was also investigated (in all except May 2010 GME).

URS had proposed to undertake site characterisation; monitoring and limited remediation to ensure the site meets lease hand back criteria and auditor requirements for the development of a more sensitive land use.

The adopted groundwater investigation levels used were the ANZECC 2000 Freshwater and
Marine Water 95% guidelines.

Inadequacies of the QA/QC program are discussed in Section 5.1 QA/QC Review.

The scope, field observations and guideline exceedances are summarised in Table 20 above, and a summary of the dissolved phase impacts for each quarterly monitoring round is provided in the sections below. It is noted that there were no guidelines used for TPH and as such any detection above LOR is discussed. The URS GME reports are provided in Appendix C.

7.3.1 Groundwater monitoring event, URS Australia Pty Ltd, May 2010

Overview of contamination status

The extent of the dissolved phase contaminants detected was reported at the following locations (refer to Figure 2 for former infrastructure and groundwater monitoring well locations):

• TPH (Area 1 to 4 and Off-site): On-site, dissolved phase TPH was reported at a total of
13 wells, in Areas 1 (MW01 to MW03), Area 2 (MW07, MW09, MW11, MW15, MW16 and MW110), Area 3 (MW05, MW13 and MW18) and Area 4 (MW21). Off-site, dissolved phase TPH was reported at three offsite wells (MW115, MW117 and MW119).

• BTEX (Area 1, 2, 3 and Off-site): On-site, dissolved phase BTEX was reported at eight of the 13 wells mentioned above, in Areas 1 (MW01 to MW03), Area 2 (MW07, MW09, MW11 and MW15) and Area 3 (MW13). Off-site, dissolved phase BTEX was reported at one offsite well (MW119). There were no BTEX results greater than adopted investigation levels.

• Lead (Area 1 to 4 and Off-site): On-site, dissolved lead impact was reported in total of seven wells, Area 1 (MW01, MW06 and MW103), Area 2 (MW07), Area 3 (MW12 and MW14) and Area 4 (MW20). Off-site, dissolved phase lead impact was reported at one offsite well (MW102).

• Total PAH (Area 1 to 4 and Off-site): Onsite, dissolved Total PAH concentrations were reported above the LOR at 10 onsite wells, within Area 1 (MW02 and MW03: naphthalene and fluorene), Area 2 (MW07, MW09, MW15, MW16: naphthalene and MW11: naphthalene, acenaphthene, fluorene, phenanthrene), Area 3 (MW05 and MW13: naphthalene) and Area 4 (MW20: naphthalene). Off-site, dissolved Total PAH concentrations were reported above the LOR at one offsite well (MW120: naphthalene).

• Phenolic Compounds (Area 2): Onsite, dissolved phenolic compounds were detected at one well, in Area 2 (MW07: phenol).

7.3.2 Groundwater monitoring event, URS Australia Pty Ltd, August 2010

Overview of contamination status

The extent of the dissolved phase analytes detected was reported at the following locations
(refer to Figure 2 for former infrastructure and groundwater monitoring well locations):

• TPH (Area 1 to 4 and Off-site): On-site, dissolved phase TPH was reported at a total of
17 wells, in Areas 1 (MW01 to MW03), Area 2 (MW07, MW09 to MW11, MW15, MW16 and MW110), Area 3 (MW05, MW13 and MW18) and Area 4 (MW21). Off-site, dissolved phase TPH was reported at three offsite wells (MW115, MW117 and MW119).

• BTEX (Area 1, 2 and Off-site): On-site, dissolved phase BTEX was reported at nine of the 17 wells mentioned above, in Areas 1 (MW01 to MW03), Area 2 (MW07, MW09, MW11 and MW15). Off-site, dissolved phase BTEX was reported at two offsite wells (MW115 and MW119).

• Lead (Area 1, 2 and Off-site): On-site, dissolved lead impact was reported in total of seven wells, Area 1 (MW103), Area 2 (MW07 and MW11), and Area 3 (MW12). Off-site, dissolved phase lead impact was reported at three offsite wells (MW108, MW115 and MW122).

• Total PAH (Area 1 and 2): Onsite, dissolved Total PAH concentrations were reported above the LOR at four onsite wells, within Area 1 (MW01 and MW03: naphthalene; MW02: naphthalene, fluorene and phenanthrene) and Area 2 (MW11: naphthalene and phenanthrene).

• Phenolic Compounds (Area 1 and 2): Onsite, dissolved phenolic compounds were detected at a total of four wells, in Area 1 (MW101: Phenol & 2-chlorophenol) and Area 2 (MW07: Phenol; MW11: 2,4-Dimethylphenol; MW110: Phenol & 3,4-Methylphenol).

• Evidence of natural attenuation of hydrocarbons has been observed in areas of impact at the site as evidenced by reduced dissolved oxygen, reduced nitrate, elevated ferrous iron and elevated methane concentrations.

7.3.3 Groundwater monitoring event, URS Australia Pty Ltd, November
2010

Overview of contamination status

During the collection of the groundwater physico-chemical field parameters in the previous GME (August 2010), the TDS values were significantly elevated in comparison to the historical readings at MW109 and MW122, with results of 19, 045 mg/L and 42,705 mg/L respectively. However, the TDS readings at these locations during the November 2010 GME were back to similar readings as compared to the reading prior to the August 2010 GME and as such the August 2010 results were considered to be anomalous.

The extent of the dissolved phase analytes detected was reported at the following locations
(refer to Figure 2 for former infrastructure and groundwater monitoring well locations):

 TPH (Area 1 to 4 and Off-site): On-site, dissolved phase TPH was reported at a total of
15 wells, in Areas 1 (MW02, MW03, MW06 and MW101), Area 2 (MW07 to MW09, MW11, MW15 and MW16), Area 3 (MW05, MW13 and MW18) and Area 4 (MW21 and MW22). Off-site, dissolved phase TPH was reported at 2 offsite wells (MW117 and MW119).

 BTEX (Area 1, 2, 3 and Off-site): On-site, dissolved phase BTEX was reported at eight of the 15 on-site wells mentioned above, in Areas 1 (MW02, MW03 and MW101), Area 2 (MW07, MW09 and MW15), Area 3 (MW05). Off-site, dissolved phase BTEX was reported at 1 of the off-site wells mentioned above (MW119).

 Lead (Area 1, 2, 3, 4, 5 and Off-site): On-site, dissolved lead impact was reported in total of eight wells, Area 1 (MW06 and MW103), Area 2 (MW07 and MW10), Area 3 (MW12 and MW14), Area 4 (MW20), Area 5 (MW106). Off-site, dissolved phase lead impact was reported at three offsite wells (MW102, MW108 and MW120).

 Total PAH (Area 1, 2 and 3): Onsite, dissolved Total PAH concentrations were reported above the LOR at 10 onsite wells, within Area 1 (MW02 and MW03: naphthalene, Fluorene and phenanthrene; MW101: naphthalene), Area 2 (MW07, MW09 and MW15: naphthalene; MW11: naphthalene, Fluorene, phenanthrene) and Area 3 (MW05, MW13 and MW18: naphthalene).

 Phenolic Compounds (Area 1, 2, 4 and off-site): Onsite, dissolved phenolic compounds were detected at a total of four wells, in Area 1 (MW03: 3, 4-methylphenol and 2-methylphenol), Area 2 (MW07: phenol), Area 4: (MW21: 3, 4-methylphenol and 2- methylphenol). Off-site, dissolved phenolic compounds were detected at one off-site well (MW120: 3, 4-methylphenol).

 The biodegradation of dissolved phase hydrocarbon impact has been observed at the Site, preferentially in the presence of dissolved oxygen, ferric/ferrous iron and sulphate. Attenuation of hydrocarbon breakdown products by methanogenesis has been observed across the Site at impacted locations in the absence of more readily available electron acceptors.

Monitoring wells with reported impact are located within the footprint of former Above Ground Storage Tanks (ASTs) or in close proximity to former infrastructure. This is consistent with previous monitoring events at the site.

7.3.4 Groundwater monitoring event, URS Australia Pty Ltd, February 2011

Overview of contamination status

The extent of the dissolved phase analytes detected was reported at the following locations
(refer to Figure 2 for former infrastructure and groundwater monitoring well locations):

 TPH (Area 1 to 4 and Off-site): On-site, dissolved phase TPH was reported at a total of
14 wells, in Areas 1 (MW01 to MW03 and MW06), Area 2 (MW07, MW09, MW11, MW15 to MW17), Area 3 (MW05, MW13 and MW18) and Area 4 (MW21). Off-site, dissolved phase TPH was reported at two offsite wells (MW117 and MW119).

 BTEX (Area 1, 2, 3 and Off-site): On-site, dissolved phase BTEX was reported at six of the 14 on-site wells mentioned above, in Areas 1 (MW01 to MW03), Area 2 (MW07 and MW15), Area 3 (MW13). Off-site, dissolved phase BTEX was reported at one of the off- site wells mentioned above (MW119).

 Lead (Area 1, 2 and 3): On-site, dissolved lead impact was reported in total of four wells, Area 1 (MW01 and MW103), Area 2 (MW07) and Area 3 (MW14).

 Total PAH (Area 1, 2 and 3): Onsite, dissolved Total PAH concentrations were reported above the LOR at six onsite wells, within Area 1 (MW02: naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, benzo(a)anthracene and chrysene and MW03: naphthalene and fluorene), Area 2 (MW15: naphthalene; MW11: naphthalene and fluorene) and Area 3 (MW05 and MW13: naphthalene).

 Phenolic compounds (Area 1 and 2): Onsite, dissolved phenolic compounds were detected at a total of two wells, in Area 2 (MW07: phenol and 3, 4-methylphenol and MW10: 3, 4-methylphenol).

7.3.5 Groundwater monitoring event, URS Australia Pty Ltd, June 2011

Overview of contamination status

The extent of the dissolved phase analytes detected was reported at the following locations
(refer to Figure 2 for former infrastructure and groundwater monitoring well locations):

 TPH (Area 1 to 4 and Off-site): On-site, dissolved phase TPH was reported at a total of
14 wells, in Areas 1 (MW01 to MW03, MW06 and MW103), Area 2 (MW07, MW11, MW15 to MW17), Area 3 (MW13 and MW18) and Area 4 (MW21 and MW22). Off-site, dissolved phase TPH was reported at five offsite wells (MW102, MW112, MW113, MW117 and MW119).

 BTEX (Area 1 and 2): On-site, dissolved phase BTEX was reported at five of the 14 on- site wells mentioned above, in Areas 1 (MW01 to MW03) and Area 2 (MW07 and MW15).

 Lead (Area 1 to 3 and 5): On-site, dissolved lead impact was reported in total of four wells, Area 1 (MW103), Area 2 (MW07), Area 3 (MW14) and Area 5 (MW106).

 Total PAH (Area 1 to 3 and Off-site): Onsite, dissolved Total PAH concentrations were reported above the LOR at seven onsite wells, within Area 1 (MW02: Napthalene, Fluorene and Phenanthrene; MW01 and MW03: Napthalene), Area 2 (MW07 and MW15: Napthalene; MW11: Fluorene and Phenanthrene), Area 3 (MW13: Napthalene) and one off-site well (MW117: Napthalene and Fluorene).

 Phenolic Compounds (Area 2): Onsite, dissolved phenolic compounds were detected at one well, in Area 2 (MW07: Phenol).

8. Summary of findings by investigation
area

The identified soil and groundwater impacts at each of the five investigation areas prior to remediation are summarised in Section 2.3 of the CUTEP (URS, 2013b) and Appendices D to H of the HERA (URS, 2013c). Conceptual understanding of the impacts prior to remediation is shown as soil exceedances above guidelines in Figures 6, 7, 8 of the validation report (URS,
2013a). Groundwater results prior to remediation are shown on Figures 11-17 of the Validation
report (URS, 2013a). In summary:
Area 1 – the western elevated corner of the Site. Soil impacted by TPH was identified in soil to overlying bedrock within the footprints of former site infrastructure such as fuel gantry, drum shed and platform, stormwater system, mechanical workshop, truck filling sheds and fuel lines. Soil vapour results for 2,2,4-Trimethylpentane (TMP) in 2008 and 2010 exceeded guideline values.

Groundwater impact consisting of dissolved phase BTEX and TPH was identified in the vicinity of the former fuel filing gantry and drum shed (MW02 and MW03) and dissolved phase benzene and TPH in the vicinity of former USTs (MW01).

Area 2 – northern corner of the site. TPH impact in soil was identified in soils overlying bedrock in the vicinity of former rail siding/oil line on the northern boundary, and in fill and soil in the historical dumping area for sludge. Ethylbenzene and TPH (including TMP) was observed in soils and fill within the northern retention basin. Extensive TPH soil impact was identified in fill and soils throughout the filled in area for AST bases. In groundwater, significant dissolved
phase BTEX and TPH C6-C36 was identified in the vicinity of the former ASTs 1 and 2. Dissolved lead was also reported exceeding adopted investigation levels in some wells in this area.

Area 3 – central portion of the site, between the escarpment that defines the eastern edge of Area 1 and the storm water drain running southwest to northeast through the site. Soil impacted with ethylbenzene and TPH was present in the vicinity of former oil lines, central retention basin and AST 11. Minor groundwater impacts (TPH C10-C36) have been identified in the vicinity of the central retention basin, down gradient of former ASTs 3, 8 and 11 and associated pipework and down gradient of former Area 1 USTs. Minor exceedances of lead
have also been observed in MW05 in the vicinity of former USTs S5, S6 and S7.

Area 4 – eastern corner of the site. Soil impact was identified as TPH C6-C36 in fill and soils to
3 m in the vicinity of former oil lines and ASTs 9, 10 and 15. No groundwater impact exceeding screening criteria was reported in Area 4.

Area 5 – south-eastern portion of the site. No soil or groundwater exceeding screening
criteria or SSTLs was reported in Area 5. PFOS was detected in soil at seven out of 14 locations at concentrations 2-3 orders of magnitude less than the US EPA soil screening criteria.

9. Remediation works undertaken

9.1 Remediation objective

The scope and objectives of the remediation work were prepared in a work plan and provided to the auditor for review (Proposal for Targeted Source Investigation and Impact Removal and to Fill Data Gaps for Validation Assessment, 1 July 2011, URS included in Appendix P of URS,
2013a). The objective was to remove contamination that might adversely affect the use of the site as it is proposed to be developed.

Unconsolidated soils in Areas 2 and 3 that were impacted with hydrocarbons were targeted for remediation. The works essentially comprised excavation, land farming and reinstatement. URS considered that it was not practical to investigate, identify and remove all sources of
contamination across the site, as the location of contamination is within bedrock and this would effectively require excavation of the escarpment rock. At the time of the investigation, excavation, land farming and remediation site works, the approaching wet season placed constraints on the timeframe available for land farming, and as such the objective was limited to a reduction in concentrations of hydrocarbon impact in the unconsolidated material excavated from the most heavily impacted areas identified within the timeframe available.

The remediation work undertaken is detailed in the URS Validation report (2013a) and is summarised below.

9.2 Source removal

Where sources of soil and groundwater contamination were identified, these were removed, including:

9.2.1 Removal of primary sources

All on site infrastructure including ASTs, USTs, loading gantries, valve exchanges and associated product delivery lines were decommissioned and removed from site in 2005/2006.

URS remediation in 2011 included locating and removing any remaining buried pipework. During remediation work undertaken in 2011, URS excavated test pits along the former alignment of product lines to ensure all lines were removed.

Details of removal of primary sources and confirmation of infrastructure removal are included in Section 3.2 of the CUTEP (URS 2013b) and in Section 10 of Addendum A to the Validation report (URS, 2013a).

URS reported that they were confident that product lines have been removed, but note that stormwater/drainage infrastructure may remain on site. This is discussed further in Section 10 of Addendum A of the Validation report (URS, 2013a).

9.2.2 Removal of secondary sources – remediation of impacted soil

Large portions of hydrocarbon impacted unconsolidated material in the lower site area were excavated (in Areas 2 and 3). During 2011 works, areas of residual hydrocarbon impact were delineated and found to be laterally extensive. Areas of residual hydrocarbon impact were generally associated with a smear zone between the wet and dry season water table and in close proximity to former ASTs 1, 2, 4, 14 and S8, pipework, ships manifold and retention basins (Areas 2 and 3). The excavations of hydrocarbon impacted material were extended laterally until no indication of petroleum related staining or odour was noted in the field, and as far as practicable toward the Site boundary and site drainage features without compromising their integrity. Excavations were typically extended vertically to the top of the bedrock (where refusal occurred) or to intersection with the dry season water table (both approximately 3-
4 mBGL). Figure 6 shows the lateral extent of excavation areas.

Hydrocarbon contaminated soil was transferred to the designated remediation area on the site for land farming and reinstatement.

Near surface unconsolidated material (up to 1.5 mbgl) was characterised as being non- impacted and was stockpiled separately and re-used (approximately 8500 m3). There were some areas (in the vicinity of test pits TP18, TP21, TP24B) where the near surface layer was found to be impacted and this was separated.

A small area of predominantly heavy end TPH impact was identified in the vicinity of the former drum shed in Area 1, and was excavated and disposed off-site.

No bulk earthworks and land farming occurred in Areas 4 and 5.

9.3 Land farming program

Land farming of hydrocarbon contaminated soil was carried out to reduce the mass of hydrocarbon contamination in the impacted unconsolidated material through the central portion of the Site (Areas 2 and 3).
Following excavation, soil (approximately 12,000 m3) was removed and stockpiled in areas based on its origin and land farmed on the flat elevated western portion of the site. Stockpile 1 consisted of material from excavation 1, stockpile 2 from excavation 2, stockpile 3 from exaction
3 and stockpile 4 from excavation 4. Land farming activities were undertaken for a minimum of four weeks. Once the bulk of the soil recorded TPH concentrations below the adopted guideline concentrations, soil was returned to the area of origin and reinstated. At completion of the reinstatement, 1 m thickness of non-impacted material was used to cover the land farmed material.

A number of samples were taken following excavation, stockpiling and turning of material from impacted test pits for the purpose assessing short term COPC loss by volatilisation and bioremediation prior to broad scale excavation and land farming. Land farming of material within the available timeframe demonstrated the typically significant and rapid loss of COPC mass by volatilisation and biodegradation of hydrocarbon impacts in soils at the Site.

Rapid biodegradation of hydrocarbons was observed to occur in the land farming operation, with a significant (65-85%) decrease in TPH concentrations in the treated material being achieved prior to reinstatement in the original excavations.

9.4 Excavation and off-site disposal

In September 2012, remnant soil impact in the vicinity of the former fuel gantry and drum shed area (within Area 1) was delineated by 17 targeted push tubes at locations of previously identified impact (BP03-1 to BP03-10, BP102-1 to BP102-2 and BP02-1 to BP02-5). Push tubes samples were taken at not more than 5 m intervals from the central location of interest as detailed in Addendum A of the Validation Report (URS 2013a) (refer to Section 6.4.2 of this report for details). Contaminated material from an area approximately 20 m x 20 m was excavated to the upper surface of the bedrock and disposed of off-site.

Exceedances from test pits TP03_03 and TP03_04 were disposed off site.

Soils removed from the excavation were transported by truck to the Shoal Bay Municipal Waste Facility. The waste disposal certificate is available in Appendix G of Addendum A of the Validation report (URS, 2013a).

9.5 Validation program

Detailed validation of the site was undertaken to identify that contamination was not present at concentrations of potential concern to users of the site. Validation samples were collected from the walls and base of the excavations prior to reinstatement of land farmed soils.

The base and walls of impacted material excavations (Areas 2 and 3) were validated following removal of impacted material to a practicable extent. Sampling of the excavation walls was undertaken at approximately 20 m intervals along the perimeter of the excavations, and sampling of the base of excavations was targeted to areas of discolouration in the bedrock or residual soils at the limit of excavation. A total of 53 samples (EX1VAL_1-14, EX2VAL_1-15, EX3VAL_1-11 and EX4VAL_1-13) were collected from the excavations during the validation program.

Soil hydrocarbon impacts were identified (and remain) at the top of and within the bedrock in areas closely associated with former infrastructure across the Site. It can be expected that adsorbed phase residual hydrocarbon impact will remain within bedrock as a smear zone within fracture infilling and weathered margins of fractured bedrock. Residual hydrocarbon impact was not removed or land farmed where it was judged not practicable to do so, such as where contamination was within bedrock or where it could not be excavated without compromising the integrity of perimeter surface water control and site boundary infrastructure.

Following the excavation in Area 1, five validation samples (Exc_PLJCN and Exc4_01 to 04) were collected from the base of the excavation and consisted of unconsolidated material from a thin layer of remnant soil and weathered rock that was not possible to remove with the excavator. Eight validation samples were collected from the walls (Exc4_NE_01 and Exc4_NE_02, Exc4_NW_01 and Exc4_NW_02, Exc4_SE_01 and Exc4_SE_02, and Exc4_SW_01 and Exc4_SW_02).

The impacts remaining on site and the results of the validation program are discussed further in
Section 10 and in the Validation report (URS, 2013a).

9.6 Effectiveness of the remediation

URS notes in the CUTEP report (URS 2013b) that land farming of impacted unconsolidated material resulted in a 65-85% decrease in TPH concentrations. Some impacts remain on site and these are discussed in the following sections.

9.7 Remediation objectives and end points

Remediation was focussed on removal of unconsolidated soil to reduce concentrations. Due to timing constraints of the wet season limiting land farming opportunity, the remediation was focussed on excavating material from the most heavily impacted areas of the site and within the timeframe available. Land farming of material within the available timeframe demonstrated the typically significant and rapid biodegradation of hydrocarbon impacts in soils at the Site.

For soils, remediation end points were SSTLs described in CUTEP and HERA (URS, 2013b and
2013c).

9.8 Groundwater

No direct treatment of groundwater for remediation occurred. The removal of primary and secondary sources of groundwater contamination was the approach adopted to clean up groundwater.

It can be expected that biological degradation of the hydrocarbon contamination will occur naturally over time, and that this will result in the reduction of the residual contamination.

Four GMEs have been undertaken by URS post-remediation to monitor the effectiveness of the remediation and of the on-going natural attenuation. The results are summarised in Section 10 of this report.

As noted in Section 1.4.2, a CUTEP report for the site has been prepared by the Auditor, Environmental Audit, 38 McMinn Street, Darwin, Clean Up to the Extent Practicable of Groundwater (CUTEP) Report (GHD, 2014). This report outlines the assessment, remediation and management of groundwater pollution at the site. It describes the methodology to achieve clean up to the extent practicable of the groundwater, the actions undertaken to remove potential sources, and the requirements to ensure that the residual groundwater pollution does not impact on beneficial uses of the site. The CUTEP report is included in Appendix H of this audit report and was provided to NT EPA for comment. A Groundwater Management Plan has since been developed to ensure that residual groundwater contamination is managed to avoid adverse effects on beneficial uses. This is included as Appendix B of the SMP. The SMP is included as Attachment B to the Statement of Environmental Audit, located at the beginning of this report.

9.9 Natural attenuation

It can be expected that biological degradation of the hydrocarbon contamination will occur naturally over time, and that this will result in the reduction of the residual contamination. URS has provided information supporting the conclusion that natural attenuation of residual hydrocarbon contamination is occurring as outlined below. Further detail is provided in
Section 3.5 of URS CUTEP (2013b) and Appendix J of the HERA (URS, 2013c).

URS concluded that there are multiple lines of evidence supporting the conclusion that active natural biodegradation processes are occurring at the site:

 The primary line of evidence is that historical contamination data demonstrates that the plume mass and/or concentrations are diminishing over time; and

 Secondary lines of evidence are the use of chemical and geochemical analytical data to confirm that there is a loss of contaminant mass.

9.9.1 Primary lines of evidence

The primary line of evidence that natural attenuation is occurring is where historical data shows that a plume is shrinking or stable. URS has undertaken an assessment of plume stability and the potential for groundwater impacts to migrate off-site and discharge to the harbour
(Appendix J of the HERA (URS, 2013c)). URS notes:

 The site history indicates that hydrocarbon contamination had been occurring for a number of years from a number of sources. Hydrocarbon storage on the site ceased in October 2005. Site observations indicate that the spread of the plume has been limited.

 Site observations indicate that the concentrations of hydrocarbons appear to be decreasing at most locations over time, and that the extent of the hydrocarbon plumes is stable or shrinking.

 The body of temporal data for dissolved hydrocarbons and BTEX compounds supports the conclusion that the mass of contamination has decreased.

 Wells down-gradient of on-site wells do not show evidence for concentration increases, indicating that the primary groundwater plumes at the site are localised and spatially stable.

 Groundwater levels may fluctuate up to 4 m between wet and dry seasons and the contaminant plume tends to be seasonally variable as contaminants are adsorbed and remobilised.

The auditor has reviewed the data and concludes that it is consistent with the plume mass and concentrations diminishing over time.

9.9.2 Secondary lines of evidence

Secondary lines of evidence that natural attenuation is occurring are where a comparison of chemical indicators in and out of the plume indicates that bioremediation is occurring.

URS notes that monitored natural attenuation parameters (MNA) from monitoring in January and June 2012 (October 2012 and March 2013 GMEs did not include MNA) show that there is good evidence for aerobic biodegradation (in the presence of dissolved oxygen), ferric iron reduction and sulphate reduction. Attenuation of hydrocarbon breakdown products by methanogenisis has also been observed across the site. URS note that in the wet season oxygenated rainwater is likely to promote aerobic biodegradation, and in the dry season the absence of oxygenated rainwater is likely to promote methanogenisis.

The results are provided in Appendix J of the HERA (URS, 2013c).

The auditor has reviewed the data and concurs that the depleted oxygen, nitrate and sulphate and elevated ferrous and methane in the plume centres are indicative of hydrocarbon degradation.

9.9.3 Summary

In considering the likelihood that natural attenuation is occurring at the site and reducing hydrocarbon impact, the auditor notes:

 The hydrocarbons present and of most concern are generally simple molecules that are easy to break down (e.g. BTEX).

 A high rate of biodegradation of hydrocarbons in soils is observed. It is noted that soils with high concentrations of hydrocarbons excavated and land farmed showed rapid decline in hydrocarbon concentrations, and a high rate of biodegradation and reduction in extent of in-situ hydrocarbon contamination (including LNAPL) has been observed on the nearby Waterfront site. This is consistent with the warm Darwin temperatures, and also indicates that the geological conditions are conducive to biodegradation and are not inhibitory to the micro-organisms involved in the biodegradation processes.

 Electron acceptors (such as oxygen) are likely to be in plentiful supply. In particular, the high seasonal variation in water table levels (differences of up to 4 m have been noted) are likely to re-oxygenate the affected areas, and sea water intrusion onto the most north easterly portion of the site is likely to be a good source of sulphate (also an electron acceptor).

9.10 Clean up to the extent practicable

A Clean Up to the Extent Practicable (CUTEP) report was submitted to the EPA in February
2014 (reference 22/15171/102081), a copy of which is provided in Appendix H. Confirmation that the NT EPA was satisfied that groundwater pollution has been cleaned up to the extent practicable was received on 28 May 2014 (reference EN2013/0038-0021), a copy of this letter is provided in Appendix B.

10. Site conditions post remediation

10.1 Summary of final condition of the site

The following section details the remaining contamination identified on the site in soil and groundwater by laboratory testing of samples and/or field observations, and the outcome at the conclusion of site works involving extensive excavations in Areas 2 & 3 and a minor excavation in Area 1.

10.2 Nature and extent of residual soil impact

URS notes in the Validation report (URS, 2013a) that soil hydrocarbon impacts remain at the top of and within the bedrock in areas closely associated with former infrastructure across the Site. Figure 7 shows the residual impacts.

Where refusal on bedrock occurred at the base of test pits or excavations in the vicinity of former infrastructure, adsorbed phase residual hydrocarbon impact is expected to occur as a smear zone within bedrock fracture infilling and weathered margins of fractured bedrock. A wet season and dry season schematic profile of the Site were presented by URS and copies are provided as Figure 8 and 9.

Little or no volatile TPH or BTEX was identified, with the majority of the impact being heavier TPH (C10+). URS notes that a significant decrease in TPH concentrations was recorded in land farmed material prior to reinstatement. Reinstated land farmed soil in Areas 2 and 3 have been covered with at least 1 m of non-impacted cover. Remnant impact in Area 4 is located at least
1 m below the site surface. Trimethylpentane (TMP or iso-octane) was observed in soil and
groundwater at the site during September to November 2012 site investigations. The areas of soil where TMP was observed were removed as part of the excavations.

Vapour risks to human health from remaining on site soil impacts are discussed in the HERA (URS, 2013c) and the auditor’s assessment of risks for the residual soil impacts are discussed in Section 11.

Residual impacts in each of the five areas are summarised in the following sections and further detail is provided in the validation report, (URS, 2013a).

10.2.1 Area 1 - the western elevated corner of the Site

As discussed in Section 6.4, impacts in some test pits were not delineated and remain on site. Remnant soil impact in the vicinity of the former fuel gantry and drum shed area (TP03-3 and TP03-4) was delineated by targeted push tubes and were excavated and disposed off-site between September and November 2012 (URS 2013a, Addendum A). During the push tube investigation, some impacts were identified that were not excavated. Following excavation of the impacted material, validation was conducted by collection of soil samples from the base
(remnant soil on the top of bedrock) and walls of the excavation, and sediment from within
stormwater pipework (PL01 and PL02). Fourteen validation samples were submitted to the primary laboratory (ALS) for analysis. Staining was noted on the base of the excavation. In particular:

 Exc_PLJCN and Exc4_01 to 04 were collected from the base of the excavation and consisted of unconsolidated material from a thin layer of remnant soil and weathered rock that was not possible to remove with the excavator. Wall validation samples exceeding guidelines for TPH C10-36 were Exc4_NE_01, Exc4_NW_02, Exc4_SE_01,
Exc4_SE_02, Exc4_SW_01, Exc4_SW_02.

 From the push tube investigation in September 2012, TPH C10-C36 fraction impacts remain on site at locations BP02-3, and BP03-10.

 The stormwater pipes (PL01 and PL02) were disposed of off site.

The residual impacts are discussed in Appendix D of the HERA (URS, 2013c) and shown on Figures 4 and 5 of Addendum A of the Validation report (URS, 2013a). URS note that validation samples collected from the base of the excavation consisted of unconsolidated material from a thin layer of remnant soil and weathered rock that was not possible to remove with the
excavator and did not consider that these sample results represent significant remnant impact.

A summary of the residual soil impacts exceeding investigation levels remaining on site in Area
1 as identified through test pits, soil bores and excavation validation samples is provided in Table 21 below. The assessor and the auditor have undertaken an assessment of the risks associated with these remaining impacts and this is discussed in Section 11.
Table 21 Area 1 residual soil impacts

Location Sample Depth (m) TPH C6-C9 TPH C10-C36 (mg/kg) (mg/kg)
NSW EPA IL
65
1000
Test pits (2011)

TP02_011
0.1
2270
TP02_012
0.5
2140
TP02_013
1
1280
TP02_031
0.1
171
5060
TP02_032
0.4
128
3640
TP03_021
0.1
5580
TP03_051
0.1
5080
TP03_073
1.0
2130
TP03_074
2.0
2070
TP07_011
0.1
1730
TP15_012
0.5
1140
TP31_011
0.0
2160
TP31_012
0.1
1440
TP31_013
0.5
1520
TP31_014 1.0 1240
TP31_015 1.1 1510
TP34_012 0.4 1050
Soil bores (2012)
BP02-3 0.3 1930
BP03-10 0.2 2840
BP03-10 0.6 3130
Excavation Validation
Base Exc_PLJCN 0.6 5800
Base Exc4_01 0.6 15010
Base Exc4_02 0.6 12160
Base Exc4_04 0.6 10430
North-east wall Exc4_NE_01 0.4 1590
North-west wall Exc4_NW_02 0.4 8200
South-east wall Exc4_SE_01 0.4 1550
South-east wall Exc4_SE_02 0.4 1640
South-west wall Exc4_SW_01 0.4 4310
South-west wall Exc4_SW_02 0.4 5980

10.2.2 Area 2 and 3 - northern corner and central portion of the site

In Areas 2 and 3, targeted excavation and landfarming was carried out of unconsolidated hydrocarbon impacted material identified during the test pitting works. It is noted that some residual soil impacts remain in locations of test pits TP16_04 and TP33_02 where impacted soil was encountered and was not excavated.

Following the excavation undertaken in Areas 2 & 3, validation works were undertaken to clarify and validate the nature of the residual hydrocarbon contamination across the site, and to
assess that contamination unsuitable to remain on site had been removed. The base and walls of impacted material excavations (Areas 2 and 3) were validated following removal of impacted material to what URS considered to be a practicable extent.

The validation program comprised 53 validation samples from the four excavation areas from 11
July 2011 to 8 December 2011. 38 validation samples were collected from the Area 2 excavations, which included “Excavations 1, 2 and 3” and 15 validation samples were collected from Area 3 (“Excavation 4” and part of “Excavation 3”). For details of the validation program, refer to the URS Validation Report (URS, 2013a).

Areas of residual hydrocarbon impact were generally encountered in the smear zone between the wet and dry season water table (Figures 8 and 9) and in close proximity to former ASTs 1, 2,
4, 14 and S8, pipework, ships manifold and retention basins.

Five wall and four floor sample locations exceeded the adopted criteria. Soil excavation validation samples that have contaminant concentrations above adopted guidelines are summarised in Table 22 below, and are shown on Figure 7.
Table 22 Area 2 and 3 Residual soil impacts

Location Sample Depth (m) TPH C6- TPH C10- Ethylbenzene C9 C36 (mg/kg) (mg/kg) (mg/kg)

Adopted criteria
65
1000
3.1
Test pits

Area 2

Area 3
TP16_04

TP33_02
0.5

1
4690

2920

Excavation 1
Wall – northern extent

Wall – northern

Wall – south- eastern
EX1VAL_1

EX1VAL_3

EX1VAL_4

EX1VAL_8

EX1VAL_9
2

2
527

89
4380

1740

6320

10330

5710
5.8
Excavation 3

Base EX3VAL_7

EX3VAL_8

EX3VAL_10 3-3.5

3-3.5

3-3.5 71 1420

3800

1770
Excavation 4
Base EX4VAL_13 3-3.5 90 2360

10.2.3 Area 4 - eastern corner of the site

Excavation of impacted material for land farming was not undertaken in Area 4 as the extent of unconsolidated contaminated material was considered to be minor.

The condition of this area of the site therefore remains unchanged since prior to remediation. As discussed in Section 6.4, remaining impacts are the exceedances for TPH C10-C36 were noted in three locations during test pitting and these concentrations remain on site at depths of between
0.5 and 2.0 m. The assessment of the risk of these remaining impacts and the various building scenarios are discussed in Section 11.
Table 23 Area 4 Residual soil impacts

Sample Depth (m) TPH C10-C36 (mg/kg) Adopted criteria 1000
TP26b_01 0.5 10200

TP26b_01 2 16700

TP39_01 0.5 3370

TP40_01 1 12300

TP40_01
QC17
QC18

1.7 LOR. The results of this work were:

 Analysis of the groundwater sample collected in October 2012 from the newly installed groundwater monitoring well MW207, located down-gradient of AST2, indicated that TMP was the dominant volatile aliphatic hydrocarbon species in groundwater at this location. The estimated TMP concentration in this sample accounted for >99% of the C6-C10 aliphatic fraction. This is broadly consistent with the January 2012 samples collected
from monitoring well MW07, for which the TMP concentration was estimated to account for approximately 60% of the C6-C10 aliphatic fraction. Significant TMP concentrations (approximately 20% of the C6-C10 aliphatic fraction) were also reported for samples from the nearby monitoring well MW203, located 25 m west of MW207.

 TMP was estimated to constitute approximately 30% of the C6-C10 aliphatic fraction at MW119, located off-site in the vicinity of the former terminal precinct product transfer lines.

 TMP concentrations were estimated to constitute <10% of the C6-C10 aliphatic fraction in samples from monitoring wells MW02 and MW03, located adjacent to the drum shed and fuel filling gantry and MW09 located in the former footprint of AST 1.

 TMP was found to constitute a small fraction of the petroleum hydrocarbon impacts present in samples from MW11 and MW15 in the vicinity of AST 4.

Analytical screening results for 2,2,4-Trimethylpentane in soil and groundwater are presented in
Table 9 of the Validation report (URS, 2013a).

10.7 LNAPL

URS notes in Section 4.4 of the CUTEP report (URS, 2013b) that a measurable thickness of LNAPL (approximately 3 cm) was observed at one monitoring well in the groundwater well network for the first time since May 2008, during the March 2013 GME. URS attributed this single occurrence of LNAPL to be the result of a natural drawdown effect induced by historically low SWLs contributing to remobilisation of LNAPL trapped in pore spaces where it is immobile and stable during normal groundwater conditions. This explanation is consistent with the observation by URS in the HERA (URS, 2013c) that an inversely proportional relationship between standing water levels and reported concentrations of COPCs has been observed at the site, i.e. concentrations increase as water level decrease.

The auditor concurs with URS that the occurrence of LNAPL is likely to be due to a short term seasonal effect associated with decreased groundwater levels and its extent is confined to monitoring wells in the vicinity of former infrastructure with concentrations that may occasionally exceed dissolved phase solubility limits. The auditor notes that the Groundwater Monitoring
Plan should include monitoring to confirm that the occurrence and extent of LNAPL does not
increase significantly.

11. Assessment of risks at the site

11.1 Beneficial uses to be protected

11.1.1 Land

The proposed land use at the Site comprises a mix of high and medium density residential, commercial use and public open space.

These correspond to sensitive use (high density residential), commercial and Recreation/open space, and the protected Beneficial Uses at the Site are therefore:

 Maintenance of Modified and Highly Modified Ecosystems;

 Human Health;

 Buildings & Structures; and

 Aesthetics.

11.1.2 Groundwater

The TDS of the groundwater is low (<1000 mg/L) making it potentially suitable for all beneficial uses, however yield is low and the nature of the development and location of the site in the Darwin CBD (with reticulated water supply) means that uses such as agricultural/irrigation, primary contact recreation, potable and industrial uses are unlikely to occur. As noted in Section 2, the auditor has been previously advised by the NT Government that these beneficial uses do not require protection within the Darwin CBD, and the auditor has assumed that these beneficial uses of groundwater are not relevant at the site.

As discussed in Section 2.5, with respect to groundwater at the site, it is concluded that groundwater should not adversely affect:

 Buildings and structures either on site or off site.

 The beneficial uses of a receiving water (for example groundwater discharges to downgradient marine aquatic ecosystems).

In the following sections the potential for impact on each of these beneficial uses is assessed.

11.2 Objectives and scope of risk assessment

The objective of the Human Health and Environmental Risk Assessment (HERA) prepared by URS (URS, 2013c) was to assess whether or not soil and groundwater impacts remaining at the site represent a significant human health or environmental risk, based on the current zoning and the anticipated end use of the site including a mixture of high and medium density residential development, commercial bulky goods development, with parks and open space for the remainder of the site.

11.3 Approach to risk assessment

The risk assessment was developed by undertaking an exposure assessment, involving a qualitative assessment of receptors and exposure pathways which provided for quantitative assumptions for estimating the potential health risks associated with the identified impacts, and a toxicity assessment to identify toxicity values for the chemicals of potential concern (COPC) that can be used to quantify risks to human health associated with the calculated intake. The final step of the risk assessment was risk characterisation which incorporates the exposure assessment and toxicity assessment to provide a quantitative assessment of non-threshold carcinogenic risk and threshold risk.

To make allowance for various development options, a number of potential building types were considered in the updated HERA, including:

 Slab-on-ground high and medium density residential and commercial buildings without a basement.

 High density residential building with enclosed underground basement car park.

 High and medium density residential and commercial buildings with open car park occupying the ground floor.

 A part-underground basement car park with medium density residential constructed above.

11.4 Evaluation of soil contamination

As discussed in Section 10 above, concentrations of COPCs in soil remain on site above the levels adopted for screening purposes. Rather than assessing the risks posed by each exceedance, URS used reverse calculations to develop site-specific trigger levels (SSTLs) to assess the risk to human health posed by the residual contamination. The SSTLs represent maximum soil concentrations below which an acceptable level of risk is indicated. The risk posed by identified soil contamination can then be assessed by comparing measured soil contaminant concentrations against the SSTLs. Risks from soil contamination were calculated by URS based on the potential vapour migration from volatile and semi-volatile soil impacts beneath the site.

Where the previous assessment of soil results compared the TPH C10-36 fraction against guidelines, the SSTLs have been developed for vapour risks and therefore consider the TPH C6-9 and C10-16 fractions, which have been divided into aliphatic and aromatic fractions. The development of SSTLs is discussed in Section 6.3 of the URS HERA (URS, 2013c).

Soil SSTLs were developed for the various potential building scenarios for residential and commercial use. Separate SSTLs were developed for the top section of the site (Area 1) and the bottom section of the site (Areas 2 to 5) to reflect the different unsaturated zone geology observed in these two sections of the site.

The building types considered were:

 Residential:

– slab on ground

– basement car park

– open car park at ground level

 Commercial:

– Slab on ground

– Basement car park

The SSTLs are provided in Section 2.4.

Figure 10 shows soil samples from the site found with COPC concentrations in excess of the calculated SSTLs.

URS noted that in comparing the soil results to SSTLs by area the 2006 and 2008 results have not been included due to the fact that drilling was undertaken using a pneumatic hammer technique. It is considered that this technique results in the loss of volatile and semi-volatile petroleum hydrocarbons and, as such, these results were not considered indicative of current site conditions or appropriate for comparison to SSTLs. It was considered that samples from excavation and stockpile validation, general and targeted test pits and push tubes would be more representative of current site conditions, and these were compared to SSTLs.

The auditor however notes that the 2006 and 2008 results may have been under-reported, and has considered the significance of these results with regard to the SSTLs and the proposed allowable building types. However, the auditor agrees that more recent data in nearby locations are likely to be more reliable, and that impacts from 2006 or 2008 that were identified in surface or shallow soils are likely to have degraded over time and the risk will now be reduced.

11.4.1 Health risk to occupiers of the site - soils

The exposure pathway relevant to residents of a high or medium density development was considered by URS to be inhalation of volatile COPC identified in soil and groundwater that may migrate to outdoor air or into buildings (including car park basements).

Direct contact with impacted soil and inhalation of contaminated dusts were not considered to be significant pathways. URS noted that the majority of the site contains little unconsolidated soil, residual hydrocarbon impacts were limited to the underlying bedrock, and the site has a layer of 1 m of clean soil, making it very unlikely that there would be significant exposure to residual contamination. The auditor notes that where where these assumptions form an important component of achieving an acceptable level of risk, the SMP for the site must include appropriate controls and provisions for management of the site.

For occupiers of commercial use buildings, URS assumed that the potential exposure pathways for future on-site commercial workers would be the same as those identified for future on-site residents, although the total exposure (and therefore risk) for commercial workers is likely to be less than for residents because of reduced exposure frequency and duration.

Area 1

Residual impacts described in Section 10 were assessed against SSTLs and URS found that the soil analytical results at locations in the vicinity of the former filling gantry and drum shed exceeded the SSTLs for the residential slab on ground scenario, the commercial slab on ground scenario, and the residential with car park basement scenario.

This area has been defined as Zone B (defined by surveyed area in the SMP) as having certain limitations associated with redevelopment, and is identified as such in the statement of environmental audit for this area.

URS concluded that the remainder of Area 1 outside of Zone B would be appropriate for development for high density residential residential/commercial apartments with basement car park or high density residential/commercial apartments constructed above open ground level parking. This development area has been defined as Zone A.

Remnant impacts exceeding SSTLs across Area 1 are listed in Table D-11, of Appendix D of the URS HERA (URS, 2013c). Locations exceeding SSTLs and remaining on site such as TP02_01, TP02_03, TP03_02, BP02-3, BP03-10, and Exc4 validation samples are included in Zone B.

The auditor notes that samples from location TP31_01, located outside of the drum shed and filling gantry area, also exceeded the SSTLs for residential slab on ground but, as the concentrations were only marginally above the SSTLs, the auditor accepts that they would not pose an unacceptable risk to development.

The auditor notes that samples from 2006 and 2008 investigations including MW03, MW06, SB1 and SB112 exceeded the SSTLs for residential slab on ground and are not included within Zone B; however the 2006 and 2008 data was not relied upon by URS in development of restrictions mainly due to the understanding that degradation of hydrocarbons is active in soil and groundwater at the site. The auditor also considered that:

 Exceedances of SSTLs at MW03 were from surface samples only (0-0.2 m) and these impacts are likely to have degraded with time (samples taken in 2006), deeper samples from this location were below the SSTLs.

 Exceedances at MW06 were from 5m depth however were within one order of magnitude of the SSTLs, and nearby sample TP06-1 1 m) from this location were below the SSTLs.

 Sample location SB151 is located adjacent to MW14 and results from this location were below the SSTLs.

 Results from sample location TP25-01 located approximately 10 m to the west of MW14 (and sampled more recently in 2011) were below the LOR.

Apart from MW14, there are no exceedances of the SSTL for residential slab on ground, supporting the conclusion that this exceedance is localised and minimal in extent (based on nearby samples). On this basis, the auditor concludes that medium density slab on ground is an appropriate development option for Zone C.

Medium Density Residential is considered to consist of multi-storey and/or semi-detached residential units or apartments.

Allowable uses for Zone C are medium density residential and commercial apartments constructed as slab on grade. As discussed above for Area 2, a basement car park is considered an allowable use however this has not been considered a likely use without moisture/vapour barriers beneath the basement slab to prevent likely water ingress from seasonal waterlogging of soils.

Area 4

Area 4 soil characterisation is detailed in Appendix G of the HERA (URS, 2013c). Seven samples from locations TP26_01, TP39_01 and TP40_01 exceeded the SSTL for the residential slab on ground scenario, and three samples from locations TP26B_01 and TP40_01 exceed the SSTLs for commercial slab on ground. These exceedances are shown on Figure 10.

The area of these exceedances, in the vicinity of former AST15, has been included within
Zone D, restricting residential slab on ground development. The south-western portion of Area 4 did not have exceedances of SSTLs. URS consider that since SSTLs for the commercial slab
on ground scenario were exceeded at only two locations and are not laterally extensive, and
groundwater in Area 4 is not considered to pose a vapour intrusion risk for residential or commercial slab on ground structures. The commercial slab on ground scenario has been considered appropriate for Area 4 by URS.

With respect to the exceedances of commercial slab on ground SSTLs within Area 4, the auditor notes that there were only two exceedences, supporting the conclusion that these are localised in extent, and that with a large footprint building the average concentrations of vapours will be less than that in the immediate vicinity of the source material. In view of this, the auditor concludes that a development that is limited to slab on grade large scale commercial development (with a large footprint) will be acceptable.

None of the samples from the remaining unexcavated areas exceed the SSTLs for buildings with an open car park. Commercial or residential basement car parks are not considered for Area 4 due to practical development restrictions (depth to groundwater and seasonal water logging).

Area 5

Area 5 soil characterisation is detailed in Appendix H of URS, 2013c (HERA). No hydrocarbon impacts were identified in Area 5. As such there is not considered to be an unacceptable risk to occupiers of the site in this area, and there are no restrictions on the type of development in this area. This has been included within Zone C.

11.4.2 Health risk to workers at the site

The potentially significant exposure pathways considered for future on site workers who may be involved in short term intrusive activities such as the demolition of structures, construction of new structures and the installation of service trenches, were:

 Inhalation of volatile COPC identified in soil and groundwater that may migrate to outdoor air in shallow excavations is considered a potentially significant exposure pathway.

 Direct contact (ingestion and dermal contact) with COPC identified in soil in shallow excavations.

 Direct contact (ingestion and dermal contact) with COPC identified in groundwater that may enter shallow excavations.

The risks to intrusive workers coming into direct contact with shallow impacted groundwater are summarised in Table 6-5 of the HERA (URS, 2013c). Both the threshold and non-threshold risks are below adopted acceptable levels for chronic exposure.

On a precautionary basis, appropriate management controls should be implemented as outlined in the SMP, and appropriate occupational health and safety practices followed. This should include appropriate personal protective equipment for workers engaged in excavation or
entering confined spaces, and also to adequately consider the protection of the public and environment from possible dust or vapour emissions.

The SMP also states that works that are undertaken within bedrock may require engagement of an appropriately qualified and experienced environmental consultant to assess potential for contamination within bedrock fractures and zones of weathering.

11.4.3 Ecological risk from soil contamination

The potential for terrestrial environmental impacts associated with residual hydrocarbon contaminated soil is discussed in Section 6.7 of the HERA (URS, 2013c).

Consideration of potential ecological impacts in on-site soils has been undertaken by reference to screening criteria which are based on ecological impacts. The NEPM 1999 (as amended
2013) incorporates Ecological Screening Levels (ESLs) for petroleum hydrocarbons.

Soil results from 2011 test pitting and excavation, land farming and reinstatement works have been compared to ESLs (it is noted that in Areas 2 and 3, where impacted unconsolidated material was land farmed prior to reinstatement with not less than 1 m of non-impacted cover, statistical analysis of the material has been used for guideline comparison). A number of samples from depths shallower than 3.0 mBGL exceeded the ESLs.

In Area 1, soil impacts occur within predominantly within scrapings from residual soil on top of bedrock following excavation, and URS notes that as the residual impacts occur in bedrock and not in unconsolidated soils that would support a well-developed root zone, the occurrence of hydrocarbon contamination within the rock has less relevance to terrestrial ecolological
systems.

Areas 2, 3 and 4 were excavated and were reinstated with unconsolidated soils. These reinstated soils had concentrations of TPH C10-C14 which exceeded the ESLs; however, the areas have been covered with a minimum of 1 m of clean soil and would only pose a risk to plants with roots greater than 1 m deep.

Impacted soil remaining at the site is not considered to be readily mobilised into the local environment as the impact across much of the site is located within bedrock (Area 1 and parts of Areas 2, 3 and 4) and has been covered with at least 1 m of non-impacted cover. It is also considered that given the likely land uses of high/medium density residential and commercial, there will be limited areas where ecological receptors are present. Medium density and high density residential will not be allowed direct access to contaminated soil, through use of permanent paving and body corporate control measures.

The SMP states that it is not recommended that vegetables are grown in gardens consisting of soil derived from the site. It is noted that much of the site consists of outcropping rock but where soil is present the upper 1 m consists of site-won clean fill which is intended to act as a buffer to prevent direct contact with potentially contaminated soils at greater than 1 m depth.

It is recommended that if vegetables are to be grown that they be grown in raised beds of soil imported to site more suitable to gardening for fresh produce. The auditor considers this to be a conservative requirement.

11.4.4 Aesthetic risks from soil contamination

Odours

In the HERA (URS, 2013c), URS considered that the relevant aesthetic consideration is the potential for odours associated with volatile COPC in groundwater to migrate to the indoor or outdoor air on site.

URS derived odour thresholds from the ATSDR toxicity profiles and found that the odour thresholds are greater than the indoor and outdoor/excavation air concentrations modelled from groundwater sources presented in Table 4-6 to Table 4-10 of the HERA (URS, 2013c). Hence, odours derived from the volatile petroleum hydrocarbons associated with groundwater impacts identified at the site are unlikely to be of concern.

Vapour concentrations from identified soil sources have not been directly modelled, however, health based criteria (SSTLs) have been calculated. The maximum acceptable vapour concentrations on which these SSTLs are based are considerably lower than odour thresholds. Consequently the calculated soil SSTLs are likely to be protective against nuisance odours.

The auditor notes that hydrocarbon odours have been previously observed at the site, at the top of impacted well heads (particularly from MW07), and during disturbance of impacted soils.

The auditor undertook a series of excavations using a backhoe in October 2012 to verify that contamination was not present in areas where previous works had suggested that it was most likely that contamination might be found. This work identified some areas where there was minor transitory odour when the soil was disturbed (such as in the northeastern corner of the site), and concluded that while some odorous material might be encountered, it would be minor and limited in extent.

Odours were observed by the auditor’s assistant during a site inspection in March 2013 while URS were undertaking a GME. Odours were observed during the gauging of MW07, it is noted that at this time, LNAPL was observed in this well. A hydrocarbon odour was noted while walking around Area 1 where the groundwater samples were being collected. The origin of the odour in Area 1 was likely to be the soils; there was no significant change in odour noted when the bore was opened for sample collection.

The site was re-visited on 15 April 2013 to further investigate concerns associated with odours noted at the site. Faint hydrocarbon odours were noted when walking across the recent excavation located around MW2 and MW3 (this was about 300 mm deep) and on the down- wind side. No odours were noted in the vicinity of MW07, however there were hydrocarbon odours noted in the bore when the well cap was removed. Stronger odours were noted in MW207 when its well cap was removed. MW207 is located close to MW7. The auditor’s assistant also walked around the western corner of the site in the location of former tank and remedial works where odours were previously noted - no odours could be detected in is area.

The site was visited again in May 2013 and no odours were detected at the site (well caps were not removed).

The auditor’s assistant checked for observable odours during the most recent site inspection (April 2014) in areas of previously identified odours (including opening the well cap of MW07); none were observed.

Reaching a firm conclusion on the potential for odour is difficult; however, from the body of information available and noting that soils with a significant odour potential have been remediated, the auditor concludes that, while some transitory minor odour may be observed on soil disturbance in some localised areas, in view of the proposed development where most of the soil will be covered by buildings, pavings or grassed or vegetated areas, the contaminants that remain pose a low risk that they will give rise to objectionable odours.

The SMP (URS, 2014) advises that If odours are encountered in areas of the site where they should not be present an appropriately qualified and experienced environmental consultant should be engaged to assess the soil. The auditor considers this to be an appropriate precautionary measure.

Visual aesthetic contamination

URS identified the potential for uncontrolled fill at the site to contain debris, building material or refuse derived from the bombings of Darwin during WWII and more recently after Cyclone Tracy, however no indication of this type of uncontrolled filling was encountered during test pitting works across the Site.

Construction-related filling exists across the site at areas of former petroleum depot related infrastructure. Aesthetically impacted material was removed during excavation remediation work. Test pitting and remediation excavation targeted and removed aesthetically impacted (stained and odorous) material. There were areas of historical dumping of tank sludge, bitumen slops and soakage basins – particularly the north eastern portion of Area 2 and the central portion of the site, Area 3.

Following removal of surface vegetation across the Site (except along the riparian zone of the open stormwater drain through the middle of the Site and on steep slopes), a visual assessment of the Site surface was carried out. The site surface was scraped to remove vegetation and entrained surface soils (<0.1 m) using an excavator equipped with a 2.4 m wide shaping bucket. As the vegetation was removed the remaining surface soils were observed by URS field staff. Particular attention was paid to areas where potential dumping of tank sludge or bitumen
residue was previously reported to have occurred. There was no evidence of surface staining,
discolouration or fragments of asbestos containing material observed. It is noted that near surface discolouration and staining not observed during site surface visual assessment was observed during test pitting works.

As noted in the previous section, the auditor undertook a series of excavations using a backhoe in October 2012 to verify that contamination was not present in areas where previous works had suggested that it was most likely that contamination might be found. This work did not identify visually objectionable contamination, such as debris or hydrocarbon staining, but did conclude that it was difficult to confirm that no such material would remain at the site, although such material if present would be limited in extent.

Since the remediation work at the time of the most recent site inspection, the vegetation has grown significantly and covers much of the site.

11.4.5 Risks to buildings and structures

With respect to not adversely affecting structures, the Land SEPP requires that “Contamination must not cause the land to be corrosive to or adversely affect the integrity of structures or building materials.” The Land SEPP specifies pH, sulfate, redox potential, salinity or any chemical substances or waste that may have a detrimental impact on the structural integrity of buildings and / or other structures as indicators.

Physical parameters affecting structures have not been specifically assessed as part of site works however it is not considered that the type of contamination present in soils (hydrocarbon) would affect the integrity of structures or building materials.

11.5 Evaluation of groundwater contamination

Risks from groundwater contamination at the site have been assessed via a forward calculation to estimate threshold and non-threshold risks associated with the identified concentrations of COPC in groundwater.

11.5.1 Use of groundwater

As discussed in Section 2.5, the salinity of the groundwater at the site is low and the groundwater could potentially be suitable for a range of uses; however due to the low yield and the fact that the site is located in the Darwin CBD, it is considered that the use of groundwater at the site for potable, irrigation and industrial uses is unlikely to occur and, as advised by NT EPA, these extractive uses of groundwater are not required to be protected in the Darwin CBD.

On this basis, it is concluded that the relevant beneficial uses of groundwater are limited to protection of marine ecosystems, and buildings and structures. It is also required that the health of persons residing or working at or in the vicinity of the site should not be adversely affected through contaminants volatilising from groundwater and entering buildings.

URS has presented the findings of the risk assessment of the potential effects of groundwater contamination on the beneficial uses of the land under various building scenarios in the HERA (URS, 2013c).

11.5.2 Health risk to occupiers of the site

Vapour

On site

URS has assessed the potential for vapours from groundwater to enter buildings and to pose a risk to users of these buildings. The findings have been documented in the HERA (URS,
2013c). The findings were as follows:

 The estimated risks for Plumes 1, 2 and 4 are within acceptable levels for residents and commercial workers for the various residential and commercial building scenarios that were modelled.

 For Plume 3, located in the northern portion of the site (centred around the former footprint of AST2), the estimated risk levels arising from volatile contaminants in groundwater in the lower northern section of the site (based on measured groundwater concentrations from monitoring wells MW07 and MW207 in March 2013):

– May exceed acceptable levels for residents living on the ground floor of a slab-on- ground residential building and to occupational workers working in a slab-on-ground commercial building; and
– Are within acceptable levels for residential or commercial buildings with an open ground floor car park.
In view of this finding, URS proposes that the development of the area of the site in the vicinity of MW07 and MW207 will be restricted and designated as open space. This area has been defined as Development Zone E.

Off site

The auditor has also considered whether vapour intrusion would pose a risk to beneficial uses of the land down gradient of the site to the north or north east. It is noted that the land is currently vacant.

As discussed in Section 10.5, Plumes 1, 2 & 3 are considered to be contained within the site boundary and as such are not likely to pose a risk to potential off site land users.

URS has noted that for Plume 4, the calculated risk levels presented in URS 2013c could also be applied to off-site residential or commercial buildings that may be constructed on Barneson Street to the north or north-west of the site, should Plume 4 extend off-site beneath any such buildings. The calculations indicate that vapour intrusion will not pose an unacceptable risk to off-site buildings under such a scenario. However, the calculations were limited to slab on ground building types and did not consider basements, and it is possible that other building scenarios might be proposed. Should a development be proposed close to the site in this area, it is recommended that the potential for vapour intrusion be further assessed once the nature of the development is known.

Based on the available information, the auditor considers that vapour intrusion poses a low risk to off-site buildings. Factors supporting this conclusion are: the rate of natural attenuation is high in the warm Darwin climate and concentrations of hydrocarbons will decrease with time; the extent of contamination is limited; NAPL is not present; dissolved phase BTEX is not present; and under high rainfall conditions which can result in groundwater elevation considerable
dilution of dissolved phase hydrocarbon can be expected to occur.

Direct contact

Direct contact (ingestion and dermal contact) with contaminated groundwater that may enter shallow excavations is a potentially significant exposure pathway, but would only be likely to occur in the wet season when groundwater levels are high. The comments in the next section regarding the risk on site are relevant.

On-site

There is potential for the discharge of contaminated groundwater at the land surface in low lying areas of the site, as the groundwater level is subject to seasonal fluctuations and has been observed near surface during the wet season.

Figure 27 of the HERA (attached as Appendix C to this report) shows the areas of the site where groundwater may intersect or come close to the site surface resulting in groundwater discharging at the surface.

URS has considered this issue and concludes that:

 Groundwater exposure at the surface would only occur during and immediately following unusual extreme rainfall events and the large quantity of rain accompanying those events would greatly dilute the concentrations of contaminants in groundwater, reducing the possibility that concentrations of contaminants would lead to unacceptable levels of risk to human health or the environment.

 Figure 27 of URS 2013c (Appendix C) shows that Areas 1, 3, 4 and 5, where there is potential for groundwater to discharge at the land surface, do not coincide with the observed groundwater contaminant plumes. In Area 2 the Figure shows that the area where there is potential for groundwater discharge at the surface corresponds to the off- site area that is seasonally waterlogged following deluge rainfall events and partially intersects Plume 4.

 It is unlikely that LNAPL would be exposed at the surface. On a precautionary basis, it is proposed that the SMP for the site will include management of groundwater contact at the surface or in trenches during site works, and that site drainage should be designed during site redevelopment to manage runoff in a controlled manner during extreme rainfall periods.

The auditor concurs with the URS conclusions and provisions that will be included in the SMP and that Area 2 where the groundwater is most likely to discharge has been restricted to open space use, as development Zone E.

The SMP also notes:

Off-site

As discussed above, in the northern portion of the site there is potential for groundwater discharge at the surface over an area which extends off-site and partially intersects Plume 4. As discussed, it is likely that any rainfall events causing discharge to surface would also result in dilution of the concentration of contaminants. However, as the potential for contaminated groundwater to discharge to the surface off site exists, it is recommended that the potential risks with such discharge be further assessed should a development on the adjacent site be proposed.

11.5.3 Health risk to workers

The HERA (URS 2013c) considered the risks to on-site and off-site intrusive workers as a result of residual soil and groundwater impacts and concluded that it was low and acceptable when working above bedrock level. URS additionally note that groundwater impact does not pose a risk to on-site or off-site intrusive workers.

It is considered that contaminated groundwater will not pose an unacceptable risk to workers at the site, assuming that they take normal occupational health and safety precautions during works.

11.5.4 Aesthetic risks from groundwater contamination

URS considered the potential for odours associated with volatile COPC in groundwater and derived odour thresholds (Section 4.6 of URS, 2013c). URS found that the odour thresholds are greater than the indoor/outdoor air concentrations modelled, and concluded that odours derived from the volatile petroleum hydrocarbons associated with groundwater impacts identified at the site are unlikely to be of concern.

11.5.5 Risk to aquatic ecosystems

There are no on-site aquatic environments to consider and therefore this report focuses on the off-site aquatic environment. The off-site potential receptor for contaminated groundwater from the site is Frances Bay and Darwin Harbour located approximately 300 m north east of the site.

Dissolved phase hydrocarbons

URS presents an argument that the site contamination poses a low risk to water quality and marine ecosystems of Frances Bay and the Darwin Harbour in Section 7.4 of the HERA (URS,
2013c). Their findings can be summarised as follows:

 Wells down-gradient of on-site wells do not show evidence of increasing concentration, indicating that the primary groundwater plumes at the site are localised and spatially stable, and are generally confined to the site.

 It is observed at other sites in Darwin that there is a rapid reduction in the extent of LNAPL and adsorbed phase hydrocarbons; this provides good evidence that natural attenuation (biodegradation) of hydrocarbons is occurring. This is supported by data for dissolved oxygen, iron and sulphate reduction and methanogenesis, and the limited extent and stability of hydrocarbon plumes.

The potential for off-site migration is discussed further in Appendix J9 of HERA (URS, 2013c).

The auditor has reviewed groundwater monitoring data for off-site wells sampled since June
2012 and the findings are summarised as follows:

 Off-site groundwater sampling undertaken in June 2012, October 2012 and April 2013 indicated that wells MW112, MW113, MW120 and MW122 had no detectable TPH (results 2 mm) of LNAPL (Light Non-Aqueous Phase Liquid or phase separated hydrocarbons) in a monitoring well that did not previously contain LNAPL;

 Greater than one order of magnitude increase in concentration of a dissolved phase
COPC in groundwater over the baseline trend; and

 Trend of increasing LNAPL thickness over two consecutive monitoring rounds in a well that already contains LNAPL.

The auditor considers that these trigger levels are appropriate for initial monitoring purposes, and recommends including the following trigger:

 Any potential development or use of the land immediately adjacent to the site down gradient. Further monitoring should be considered depending on the type and timing of any potential development.

12.5.2 Contingency plan

In the event that trigger levels are exceeded the GQMP (URS, 2014) notes that further action will be required. The actions will be determined at the time through consultation between the site owner and the NT EPA, and can be expected to include assessment of the significance of
the exceedances and whether it could give rise to adverse effects, and determination of whether further follow up is required.

Further follow up could include:

 Re-sampling of existing bores or sampling on a more frequent basis in order to assess trends in greater detail;

 Installation of additional monitoring wells;

 Installation of a groundwater control drainage system;

 Localised impacted groundwater pumping including treatment system if required;

 Installation of a cut off-wall if required; and

 In the event of off site development, further assessment of the proposed development should be undertaken to consider the potential for adverse effects, particularly if buildings are proposed close to the site boundary. Consultation with down gradient off site land owner.

As discussed in Section 10.5, the land down-gradient of the site to the north and north-east is Crown Land, and the auditor consulted with the relevant Government planning department with regards to potential for development.

The Department noted that the area involved is vacant Crown Land and zoned Proposed Main Road however potentially could be developed for a range of uses, but is a natural drainage area. Any localised contamination close to the boundary might require controls if development were to involve basements.

The EPA informed GHD that in relation to the adjacent blocks of concern a notation will be made in the administrative section of the Northern Territory Land Information System indicating that the land is adjacent to a land that is the Subject of a Statement of Environmental Audit. It is expected that this will provide a sufficient prompt to identify the risks and facilitate further investigation by Planners and Developers.

It is also noted that the SMP and GQMP provide for notification of the NT EPA and Department of Lands, Planning and the Environment of any changes in monitoring data that indicate the contamination is migrating further outside the site boundaries, or any other changes that may indicate an increase in the potential for environmental harm.

In their letter dated 23 May 2014 (Appendix B), the NT EPA requested that “In relation to the adjacent lots, Barneson Street Road Reserve and Crown Land Lot 6663, that have residual groundwater impact, Shell make formal written notification to the Department of Transport and the Department of Land, Planning and the Environment informing them of the status of the groundwater impact and the statement of environmental audit and associated conditions”.

The auditor has included this as a condition in the Statement of Environmental Audit.

12.6 Periodic review of management plans

The clean up of the site will be on-going through natural attenuation. Monitoring of the progress of natural attenuation is required to ensure continued reduction of impacts on site, and that off- site ecosystems are not at risk. This will be implemented via a GQMP as described above. URS has stated that the GQMP is expected to extend for a minimum period of four years, and that a review of the GMP by NT EPA will be completed annually in order to transition to cessation of monitoring as early as is supported by the data.

It is not expected that further active remediation (such as excavation of bedrock) will be considered practicable in the future, particularly following development of the site. Assuming that groundwater contamination continues to decrease with time and does not pose an unacceptable risk to beneficial uses, it can be expected that active remediation will not be required. In the unexpected event that groundwater monitoring should show that groundwater contamination poses an unacceptable risk to beneficial uses on site or off site, the requirement for additional remediation should be considered at that time.

When groundwater monitoring results indicate that beneficial uses have been restored (i.e. there is no groundwater pollution) or it can be assured that the residual contamination does not present a risk, a submission can be made to the EPA to obtain agreement that monitoring may cease.

13. Audit conclusions

The following information is relevant regarding the condition of the Site:

Soil

 With respect to below ground works, the assessment has concluded that the residual contamination does not pose an unacceptable risk to persons working above bedrock level. It is noted:

– On a precautionary basis, the SMP outlines appropriate management controls that should be implemented, and appropriate occupational health and safety practices that should be followed. This includes appropriate personal protective equipment for workers engaged in excavation or entering confined spaces, and consideration of the need for protection of the public and environment from possible dust or vapour emissions.
– The SMP requires that, if works are proposed to be undertaken within bedrock, consideration be given to the engagement of an appropriately qualified and experienced environmental consultant to assess potential for contamination within bedrock fractures and zones of weathering.
 Hydrocarbon odours may be observed during excavations or construction in parts of the site previously impacted when the soil is disturbed (such as in the north-eastern corner of the site); however, it is expected that odorous material will be minor, limited in extent, and the odours will be transitory.

 This report included an assessment for the potential for UXO which found no evidence that explosive ordnance had impacted the site, and that the risk rating for the site was low, refer to Section 6.5.4. The work undertaken to assess contamination has included field surveys and extensive intrusive environmental investigations during 2006, 2008 and
2011, including broad scale excavation over areas of unconsolidated material and
outcropping bedrock. This work did not identify material that would suggest that impact from EO or UXO is present.

Groundwater

 There are four plumes of dissolved phase groundwater contamination beneath the site, three of which overlap in the northern section of the site (Area 2).

 Plumes 1, 2 and 4 do not pose an unacceptable risk for residents and commercial
workers for the various residential and commercial building scenarios that were modelled.

 Soil excavation and intrusive works;

 Groundwater abstraction and incidental contact; and

 Property management activities.

The Groundwater Management Plan provides information on the requirements for ongoing monitoring of groundwater at the Site.

Suitability of the site – Zone A

 High density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

2. All garden areas shall be backfilled with at least 1.0 metre of clean fill/topsoil.

3. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

4. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring.

Suitability of the site – Zone B

 High density residential apartments and/or

 Commercial retail office space.

 subject to the following conditions:

1. Buildings must be constructed above open ground level parking.

2. No slab on grade.

3. No basement car parks.

5. All garden areas shall be backfilled with at least 1.0 metre of clean fill/topsoil.

6. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

7. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring.

Suitability of the site – Zone C

 Medium and/or high density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

2. All garden areas shall be backfilled with at least 1.0 metre of clean fill/topsoil.

3. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

Suitability of the site – Zone D

 Medium and/or high density residential apartments and/or

 Commercial retail office space.

 Subject to the following conditions:

2. Medium or high density residential must be constructed above open ground level parking.

3. Larger scale commercial retail/office space may be constructed as slab on grade or above open ground level parking.

4. Smaller scale commercial retail/office space must be constructed above open ground level parking.

5. No Slab on grade for residential or small scale commercial retail/office.

6. If a basement car park is proposed, it can be expected to include a moisture/vapour barrier beneath the basement slab to prevent water ingress during the wet season when the water table is high.

7. All garden areas must be backfilled with at least 1.0 metre of clean fill/topsoil.

8. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

9. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring.

Suitability of the site – Zone E

On the basis of the work undertaken, the auditor is of the opinion that the Site (Zone E) is suitable for the intended purpose, that being open space parklands and landscaped gardens as outlined in the site contamination management plan (Attachment B).

 Subject to the following conditions:

1. No slab on grade habitable structures.

2. No accessible gardens or soil.

3. No swimming pool with enclosed change rooms/toilets or filter room.

4. All future development and maintenance works at the site involving excavation, and disposal of soil and fill shall be carried out in accordance with the Site Contamination Management Plan (Attachment B).
5. The soil shall be covered by a minimum of 1.0 metre of clean soil or fill. The soil or
fill shall be maintained at all times or otherwise replaced with the equivalent material.

6. Groundwater at the site shall be managed in accordance with the Groundwater
Management Plan (Attachment B).

7. Groundwater shall not be abstracted from the site for uses other than clean-up or monitoring.
8. In their letter dated 23 May 2014 (Appendix B), the NT EPA requested that “In relation to the adjacent lots, Barneson Street Road Reserve and Crown Land Lot
6663, that have residual groundwater impact, Shell make formal written notification to the Department of Transport and the Department of Land, Planning and the Environment informing them of the status of the groundwater impact and the statement of environmental audit and associated conditions”.

Other related information:

The limitations outlined in the next section of this report should be referred to. DATED: 4 August 2014
SIGNED:

PETER NADEBAUM

Environmental Auditor (Appointed Pursuant to the Victorian Environmental Protection Act 1970) and recognised in the
Northern Territory under section 68 of the Waste Management and Pollution Control Act (NT). Statement Attachment A: Site Development Zones and restrictions
Statement Attachment B Site Contamination Management Plan (SMP) – Current version as at 16/7/2014

14. References

Australian and New Zealand Environment and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand (ANZECC & ARMCANZ), 2000: Australian and New Zealand Guidelines for Fresh and Marine Water Quality. National Water Quality Management Strategy

Australian and New Zealand Environment and Conservation Council, National Health and Medical Research Council (1992) Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites
Australian and New Zealand Environment & Conservation Council (ANZECC), 1992: Australian Water Quality Guidelines for Fresh and Marine Waters. National Water Quality Management Strategy

Coffey Environments Pty Ltd (2006), Environmental Site Assessment Report, Former Shell
Darwin McMinn Street Terminal (ECK104D) McMinn Street, Darwin, Northern Territory, October
2006

CRC Care (2012), Technical Report no. 10 ‘Health screening levels for petroleum hydrocarbons in soil and groundwater Part 2: Application document

EPAV, (2000). A Guide to the Sampling and Analysis of Waters, Wastewater, Soils and
Wastes. Publication 441 7th Edition, March 2000

EPAV (2000). Groundwater Sampling Guidelines, Publication 669, April 2000

EPAV (2009). Sampling and Analysis of Waters, Wastewaters, Soils and Wastes, Industrial
Wate Resource Guidelines (IWRG701), June 2009

EPA Victoria (2014) The Clean Up and Management of Polluted Groundwater, Publication
840.1, February 2014

EPA Victoria (2014) Environmental auditor (contaminated land): Guidelines for issue of certificates and statements of environmental audit, Publication 759.2, February 2014

GHD Pty Ltd (2014) Environmental Audit, 38 McMinn Street, Darwin, Clean Up to the Extent
Practicable of Groundwater (CUTEP) Report, April 2014

Groundwater Technology Australia Pty Ltd (1995), Environmental Site Assessment Report, Shell Darwin Terminal, 38 McMinn Street, Darwin, Northern Territory, February 1995

IT Environmental (Australia) Pty Ltd (2001), Groundwater Monitoring Event Report, December
2000, Shell Darwin Terminal – McMinn Street, Darwin, Northern Territory, February 2001

IT Environmental (Australia) Pty Ltd (2002), Groundwater Monitoring Event Report, December
2001, Shell Darwin Terminal McMinn Street (ECK104D) Darwin, Northern Territory, January
2002

IT Environmental (Australia) Pty Ltd (2002), Groundwater Monitoring Event Report, November
2002, Shell Darwin Terminal McMinn Street (ECK104D) Darwin, Northern Territory, December
2002

National Environment Protection Council Act 1994

National Environment Protection Council Act (Northern Territory) Act 1994

National Environment Protection Council (Victoria) Act 1995

NEPC, (1999). National Environment Protection (Assessment of Site Contamination) Measure, National Environment Protection Council. December 1999

National Environment Protection Council (1999) National Environment Protection (Assessment of Site Contamination) Measure, December 1999 (as amended 2013)

National Health and Medical Research Council and National Resource Management Ministerial
Council (2008).Guidelines for Managing Risks in Recreational Water

National Health and Medical Research Council and National Resource Management Ministerial Council (2011). Australian Drinking Water Guidelines 6. National Water Quality Management Strategy, National Health and Medical Research Council

Northern Territory Environmental Assessment Act (1982)

Northern Territory National Environment Protection Council Act (1994) Northern Territory Waste Management and Pollution Control Act (1998) Northern Territory Planning Act (1999)
Northern Territory Planning Act (2007)

NSW Contaminated Land Management Act (1997)

NSW EPA, (1994). Contaminated sites: Guidelines for Assessing Service Station Sites. New
South Wales Environmental Protection Authority

The Netherlands Ministry of Housing, Spatial Planning and Environment (2000). Intervention values and target values – soil quality standards

Standards Australia, (1999). Australian Standard, Guide to the sampling and investigation of potentially contaminated soil. Part 2: Volatile substances. AS4482.2 - 1999

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

Standards Australia, (2009). Australian Standard, Piling – Design and Installation. AS2159-1995

URS Australia Pty Ltd (2008), Environmental Site Assessment, Former Shell Terminal McMinn
St Darwin (ECK104D), Northern Territory, September 2008

URS Australia Pty Ltd (2010), Draft Report, Site History Review and Summary of Previous
Environmental Site Assessments. July 2010

URS Australia Pty Ltd (2010), Draft Report, Factual Groundwater Monitoring Event Report, May
2010, Former Shell McMinn Street Terminal. August 2010

URS Australia Pty Ltd (2010), Former Shell McMinn Street Terminal Darwin - Groundwater
Monitoring Event, August 2010. December 2010

URS Australia Pty Ltd (2011), Former Shell McMinn Street Terminal Darwin - Groundwater
Monitoring Event, November 2010. February 2011

URS Australia Pty Ltd (2011), Former Shell McMinn Street Terminal Darwin – Groundwater
Monitoring Event, February 2011. March 2011

URS Australia Pty Ltd (2012), Former Shell McMinn Street Terminal Darwin – Groundwater
Monitoring Event, June 2011. February 2012

URS Australia Pty Ltd (2012), Former Shell McMinn Street Terminal Darwin - Groundwater
Monitoring Event, January 2012. February 2012

URS Australia Pty Ltd (2013), Former Shell McMinn Street Terminal Darwin – Groundwater
Monitoring Event, June 2012. April 2013

URS Australia Pty Ltd, (2013), Former Shell McMinn Street Terminal Darwin – Groundwater
Monitoring Event, October 2012. April 2013

URS Australia Pty Ltd (2013), Final Report, Environmental Validation Report with Addenda, Former Shell McMinn Terminal, Northern Territory. Works completed to April 2013. (URS,
2013a)

URS Australia Pty Ltd (2013) Clean-up to the Extent Practicable (CUTEP) Report - Shell
McMinn Terminal, August 2013 (URS, 2013b)

URS Australia Pty Ltd (2013), Human Health and Environmental Risk Assessment at the
Former Shell McMinn St Terminal, Darwin, September 2013 (URS, 2013c)

URS Australia Pty Ltd (2013) Former Shell McMinn Terminal – Qualitative PFOS Risk
Assessment, December 2013, (URS, 2013d)

URS Australia Pty Ltd (2014) Site Contamination Management Plan – Former Shell McMinn
Terminal, Darwin, July 2014

Victorian Government, (1997). State environment protection policy (Groundwaters of Victoria).
Victorian Government Gazette No. S160 17 December 1997

Victorian Government, (2002). State environmental protection policy (Prevention and
Management of Contamination of Land). Victorian Government Gazette No. S95 4 June 2002

Victorian Government, (2003). State environment protection policy (Waters of Victoria).
Victorian Government Gazette No. S107 Wednesday 4 June 2003

Appendices

Appendix A – Figures

Figure 1 Site location plan

Figure 2 Site features

Figure 3 Sampling locations all areas URS 2008, 2011 and 2012

Figure 4 Validation areas

Figure 5 Soil exceedances above adopted guidelines test pits (2011) Figure 6 Excavation locations 2011 and 2012
Figure 7 Soil exceedances above adopted guidelines excavation validation samples (2011)

Figure 8 Conceptual site model dry season Figure 9 Conceptual site model wet season Figure 10 Soil exceedances above adopted SSTLs
Figure 11 Site Management Plan – development zones and restrictions

Figure 12 Site Management Plan – development zones and restrictions with coordinates

Provided on CD

Appendix B – NT EPA Correspondence

Provided on CD

“Act” the Environment Protection Act 1970 as amended
ANZECC Australian and New Zealand Environment and Conservation Council, a council of ministers responsible for environment in state and federal government including the NZ national government.
ANZECC B concentration guidelines for contaminants issued by ANZECC in 1992 which, when exceeded, indicate that investigation of the impact of the contaminant on beneficial use (on the environment) is necessary
Assessment of site contamination a set of formal methods for determining the nature, extent and levels of existing contamination and the actual or potential risk to human health or the environment on or off-site from that contamination.
Environmental auditor means a person appointed under section 53S of the Environment
Protection Act as an environmental auditor for the purposes of that Act.
Background level the level of an indicator (measured in a manner and at a location specified by the Authority) in the surface waters of the segment outside the influence of any waste discharge containing a measurable level of that indicator.
Beneficial use beneficial use in relation to assessment of contaminated land means a use of the environment or any element or segment of the environment which: (a) is conducive to public benefit, welfare, safety, health or aesthetic enjoyment, and which requires protection from the effects of waste discharges, emissions or deposits, or (b) is declared in State environment protection policy to be a beneficial use.

Contaminant
a chemical of man-made origin that has been added to soil or groundwater

Contamination
the condition of land or water where any chemical substance or waste has been added at above background level and represents, or potentially represents, an adverse health or environmental impact.

Dutch Intervention
Levels
concentration guidelines issued by the Dutch government in 2000 which, if exceeded, indicate that remediation may be necessary

Dutch Target Level
concentration guidelines issued by the Dutch government in 2000, which, if exceeded, indicate that there may be some contamination

Ecological risk assessment
a set of formal, scientific methods for defining and estimating the probabilities and magnitudes of adverse impacts on plants, animals and/or the ecology of a specified area posed by a particular stressor(s) and frequency of exposure to the stressor(s). (Stressors include release of chemicals, other human actions and natural catastrophes).
Element of the environment in relation to the assessment of contaminated land element means any of the principal constituent parts of the environment including waters, atmosphere, land, vegetation, climate, odour, aesthetics, fish and wildlife.
EPA Environment Protection Authority of Victoria (“Authority”)
Exceedance an instance where the concentration of a substance in soil or groundwater exceeds a nominated guideline
Fill material soil (sand, clay and silt), gravel or rock with contaminant concentrations less than those specified in Table 1 of EPA Publication 448-1 entitled “Classification of Wastes”.
Groundwater any water contained in or occurring in a geological structure or formation
Health risk assessment the process of estimating the potential impact of a chemical, biological or physical agent on a specified human population system under a specific set of conditions.
Investigation level the concentration of a contaminant above which further appropriate investigation and evaluation will be required.

MAH monocyclic aromatic compounds, namely benzene, chlorinated benzenes, chlorinated phenols, phenol, toluene and xylene
mg/kg milligram per kilogram, the measure of concentration of a contaminant or naturally occurring chemical in soil, normally expressed as mg per kg of oven dry soil
mg/L milligram per litre, the measure of concentration of a contaminant or naturally occurring chemical in water
Potentially contaminated land means land used or known to have been used for:(a) industry, (b) mining, (c) storage of chemicals, gas, wastes or liquid fuel (if not ancillary to another use of the land).
Regulations a regulation made under the “Act”.
Segment of the environment segment in relation to the environment means any portion or portions of the environment expressed in terms of volume, space, area, quantity, quality or time or any combination thereof.
Sensitive use in relation to Ministers Direction No 1, sensitive use means residential use, a child-care centre, a preschool centre or a primary school
SEPP State environment protection policy

GHD

Level 3 GHD Tower 24 Honeysuckle Drive Newcastle NSW 2300
PO Box 5403 Hunter Region Mail Centre NSW 2310
T: (02) 4979 9999 F: (02) 4979 9988 E: ntlmail@ghd.com.au

This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised use of this document in any form whatsoever is prohibited.
N:\AU\Newcastle\Projects\22\15171\WP\104595.docx

Document Status

Rev
No. Author Reviewer Approved for Issue
Name Signature Name Signature Date
0 L Saunders P Nadebaum

P Nadebaum

4/08/14

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Shell Company of Australia

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URS

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