acid sulfate soils management protocol...c:\nrportbl\active\mll\27598766_1.docx...

C:\NRPortbl\Active\MLL\27598766_1.docx C:\NRPortbl\Active\MLL\27598766_1.docx Revision 1 – Revision 1 – 15-Jun-2020 Prepared for – APA Transmission Pty Limited – ABN: 84 603 054 404 Prepared for – APA Transmission Pty Limited – ABN: 84 603 054 404

Gas Import Jetty and Pipeline Project

APA Transmission Pty Limited

15-Jun-2020

Doc No. Document No

Commercial-in-Confidence

Acid Sulfate Soils Management Protocol

Pipeline Works ASS Management Protocol



Acid Sulfate Soils Management Protocol – Pipeline Works ASS Management

Protocol – Pipeline Works ASS Management Protocol




AECOM

Acid Sulfate Soils Management Protocol

Pipeline Works ASS Management Protocol

Client: APA Transmission Pty Limited

ABN: 84 603 054 404

Prepared by

AECOM Australia Pty Ltd

Level 10, Tower Two, 727 Collins Street, Melbourne VIC 3008, Australia

T +61 3 9653 1234 F +61 3 9654 7117 www.aecom.com

ABN 20 093 846 925

15-Jun-2020

Job No.: 60592634

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party should rely on this document without the prior written consent of AECOM. AECOM undertakes no duty, nor accepts any responsibility, to any

third party who may rely upon or use this document. This document has been prepared based on the Client’s description of its requirements and

AECOM’s experience, having regard to assumptions that AECOM can reasonably be expected to make in accordance with sound professional

principles. AECOM may also have relied upon information provided by the Client and other third parties to prepare this document, some of which

may not have been verified. Subject to the above conditions, this document may be transmitted, reproduced or disseminated only in its entirety.©

AECOM Australia Pty Ltd (AECOM). All rights reserved.

AECOM has prepared this document for the sole use of the Client and for a specific purpose, each as expressly stated in the document. No other

party should rely on this document without the prior written consent of AECOM. AECOM undertakes no duty, nor accepts any responsibility, to any

third party who may rely upon or use this document. This document has been prepared based on the Client’s description of its requirements and

AECOM’s experience, having regard to assumptions that AECOM can reasonably be expected to make in accordance with sound professional

principles. AECOM may also have relied upon information provided by the Client and other third parties to prepare this document, some of which

may not have been verified. Subject to the above conditions, this document may be transmitted, reproduced or disseminated only in its entirety.








AECOM

Quality Information

Document Acid Sulfate Soils Management Protocol

Ref 60592634

Date 15-Jun-2020

Prepared by Nazuha Rosli

Reviewed by Navjot Kaur

Revision History

Rev Revision Date Details

Authorised

Name/Position Signature

0 01-Jun-2020 Issue for review Mark Davidson Technical Director - Environment

1 15-Jun-2020 Final for issue Mark Davidson Technical Director - Environment








AECOM

Table of Contents

Abbreviations 5 Glossary of terms 6 1.0 Introduction 1

1.1 What are Acid Sulfate Soils? 1 1.2 Background and Purpose of ASS Management Protocol 1 1.3 Legislative Context and Guidelines 2

2.0 Site overview 2 2.1 Site Description 2 2.2 Topography and surface water 2 2.3 Regional geology and hydrogeology 3

3.0 CASS occurrence 4 4.0 Project description 4 5.0 CASS management strategy 4

5.1 Topsoil 5 5.2 Trench spoil 5

5.2.1 Avoid disturbance 5 5.2.2 Minimise disturbance 5 5.2.3 Prevent oxidation 6 5.2.4 Treat to reduce or neutralise acidity 6 5.2.5 Offsite reuse or disposal 12 5.2.6 Water management 12 5.2.7 Contingency plan 15

6.0 Monitoring program 1615 6.1.1 Trench water 1615

7.0 Performance criteria 1615 7.1.1 Soil neutralisation 1615

8.0 Timing of environmental activities 16 9.0 Reporting 16 10.0 Consultation and approvals 16 11.0 References 17

Appendix A Figures A

Appendix B Tables B

Appendix C Field Screening Testing and Interpretations C

Appendix D Acid sulfate soils field indicators D








AECOM

Abbreviations

Abbreviation Definition

AASS Actual acid sulfate soils

ANC Acid Neutralising Capacity

ASS Acid sulfate soil

ASSMP Acid Sulfate Soils Management Plan

BPMG Best Practice Guidelines for Assessing and Managing Coastal Acid Sulfate Soils

CASS Coastal acid sulfate soils

CRS Chromium Reducible Sulfur

EES Environment Effects Statement

EOLSS End of line scraper station

HDD Horizontal directional drilling

IWRG Industrial Waste Resource Guidelines

KP Kilometre point

mbgl Metres below ground level

mg/L Milligrams per litre

ML Megalitre

NA Net Acidity

PASS Potential Acid Sulfate Soils

PIG Pipeline Inspection Gauge

pHf Field pH

pHfox Field peroxide pH

ROW Right of way

RPD Relative Percent Difference

SEPP State Environment Protection Policy

SPOCAS Suspension Peroxide Oxidation – Combined Acidity and Sulfate

TAA Titratable Actual Acidity

TDS Total dissolved solids

VTS Victorian Transmission System








AECOM

Glossary of terms

Term Definition

%S A measure of reduced inorganic sulfur (using the SCR or SPOCAS methods) expressed as a percentage of the weight of dry soil analysed.

Acid Neutralising Capacity (ANC)

A measure of the ability of the ASS material to neutralise acidity.

Acid sulfate soil (ASS) Acid sulfate soils are naturally occurring soils, sediments or organic substrates that are formed under waterlogged conditions. These soils contain iron sulphide minerals or their oxidation products. When exposed, these soils oxidise and they can generate acidic water (if in contact with rainfall or other water source).

Action Criteria The measured level of potential plus existing acidity beyond which management action is required, if a soil or sediment is to be disturbed. The trigger levels vary for texture categories and the amount of disturbance. The extent of management required will vary with the level of acidity and the volume of the disturbance, among other factors.

Actual acid sulfate soil (AASS) Soils containing highly acidic soil horizons resulting from the oxidation of soil materials are rich in reduced inorganic sulfur primarily pyrite. When this oxidation of reduced inorganic sulfur produces acidity in excess of the soil material’s capacity to neutralise this acidity, the soil material will often acidify to a pH 4 or less, forming an Actual Acid Sulfate Soil (AASS). The recognition of AASS materials can be confirmed by the presence of jarosite in these materials, or the location of other AASS or Potential ASS (PASS) materials within or in the nearby vicinity to the sampling location.

Actual Acidity The soluble and exchangeable acidity already present in the soil, often as a consequence of previous oxidation of reduced inorganic sulfur. It is this acidity that will be most mobilised and discharged following a rainfall event. It is measured in the laboratory using the Titratable Actual Acidity (TAA) method. It does not aim to include the less soluble acidity (that is Retained Acidity) held in hydroxy-sulfate minerals such as jarosite.

Alignment The centreline of the ROW selected for assessment in the EES.

Bell hole Awidened area of trench, which enables horizontal boring to be undertaken.

Construction right of way (ROW) Corridor generally of 30m width.

Environment Effects Statement An Environment Effects Statement provides a comprehensive framework for the assessment of the potential environmental impacts or effects of a proposed development under the Environment Effects Act 1978.

End of Line Scraper Station An underground delivery facility situated at the connection point to the Longford Dandenong Pipeline east of Pakenham and








AECOM

Term Definition

used to launch and receive pipeline inspection gauges (PIGs) into and from the pipeline system.

Horizontal Directional Drilling (HDD)

A ‘trenchless technology’ by which a pipeline tunnel is drilled at a shallow angle under a crossing (e.g. a waterway, wetland, road or railway) through which the pipe is then threaded.

KPs Reference points alongside the proposed pipeline alignment, calculated according to the distance in kilometres from the Crib Point Receiving Facility.

Liming rate Liming rate is defined as the dose of neutralising agent needed to neutralise the calculated net acidity for a select sample.

Net acidity The measure of the acidity hazard of ASS materials. Determined from laboratory analysis, it is the result obtained when the values for various components of soil acidity and acid neutralising capacity (but only after corroboration of the ANC’s effectiveness) are substituted into the Acid Base Accounting equation.

pHFOX pH measurement based on peroxide test results in the field.

Potential ASS (PASS) Soils that contain appreciable amounts of reduced inorganic sulfur that have not oxidised but will acidify to a pH of less than 4.0 after oxidation. The soils are also known as hypersulfidic soil materials. The field pH of these soils in their undisturbed state is pH 4 or more, and may be neutral or slightly alkaline. Potential ASS pose an environmental hazard if disturbed, as they can generate considerable acidity if mismanaged.

Total dissolved solids The total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water.

Trenching Excavation of a trench for burial of a pipeline.

Trench water Water (usually shallow groundwater, rainwater or runoff) in the pipeline trench.








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1.0 Introduction

This Acid Sulfate Soils (ASS) Management Protocol has been developed to specifically address the occurrence of acid sulfate soils (ASS) associated with the Gas Import Jetty and Pipeline Project Pipeline Works (the ‘Project’). The Gas Import Jetty and Pipeline Project comprises two sets of works: the Gas Import Jetty Works and the Pipeline Works and this ASS Management Protocol is applicable to the Pipeline Works only. This document forms part of the Pipeline Works Environmental Management Plan (EMP).

The ASS Management Protocol is based on soil investigations undertaken as part of the Environment Effects Statement (EES) for the Project and includes mitigation measures listed in the EES Technical Report E: Contamination and acid sulfate soils. The procedures contained within this ASS Management Protocol should be updated and revised to address site conditions that vary from those indicated by investigations, or where alternative construction methodologies are adopted.

1.1 What are Acid Sulfate Soils?

The EPA Victoria Industrial Waste Management Policy (Waste Acid Sulfate Soils) 1999 defines ‘acid sulfate soil’ as:

‘… any soil, sediment, unconsolidated geological material or disturbed consolidated rock mass containing metal sulphides, which exceeds criteria for acid sulfate soils specified in EPA Victoria Publication 655 entitled Acid Sulfate Soil and Rock published by the Authority in 1999 and amended from time to time or republished by the Authority’.

ASS are soils affected by iron sulphide minerals. ASS can occur naturally in coastal environments such as estuarine systems, mangrove swamps, back swamps and in inland environments such as river and stream channels, lakes, wetlands, billabongs, floodplains and marshes (Fitzpatrick, R. and Shand, P., 2008).

Generally, ASS is classified into two broad types:

Potential Acid Sulfate Soils (PASS) – soil that contains un-oxidised metal sulfides. This only exists under oxygen-free or waterlogged conditions. If disturbed, it can produce acid.

Actual Acid Sulfate Soils (AASS) – soil that has been exposed to oxygen and water and is already acidic.

Presence of AASS or PASS in sufficient amounts can have a lasting effect on the soil characteristics, causing deoxygenation or release contaminants when the iron sulfide minerals are exposed to oxygen (Fitzpatrick, R. and Shand, P., 2008). They become a potential constraint to construction activities, requiring the implementation of controls to manage the spoil during excavation, trenching and drilling activities.

1.2 Background and Purpose of ASS Management Protocol

Soil sampling program undertaken as part of the EES Technical Report E: Contamination and acid sulfate soils between 29 November 2018 and 26 April 2019 identified the presence of ASS throughout the Project area for the Pipeline Works. Therefore, any soil disturbance activities such as excavation, trenching and thrust boring would have the potential to encounter ASS and oxidise PASS, and as such an appropriate level of treatment and management is required during the construction and/or maintenance works.

The open trench sections for the Pipeline Works would disturb approximately 91,500 cubic metres of soil (in-situ). Based on the volume of soil disturbance, the Pipeline Works is classified as a ‘High Hazard’ under the CASS BPMG (2010) and may only proceed with an approved environmental management plan. EPA Victoria was consulted on 19 August 2019, and it was agreed that the Pipeline Works would not require an EPA Victoria approved ASS Management Plan. Instead, an ASS Management Protocol will be developed and included in the Pipeline Works EMP which will be approved in accordance with Pipeline Act 2005, in consultation with EPA Victoria.








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The main purpose of this ASS Management Protocol is to mitigate or control potential impacts relating to the disturbance of ASS associated with the proposed earthworks and construction of the Project.

The term PASS and AASS are referred to as ASS within this ASS Management Protocol, unless there is a specific need for differentiation.

1.3 Legislative Context and Guidelines

This ASS Management Protocol has been prepared to address the requirement of the Industrial Waste Management Policy (Waste Acid Sulfate Soils), Special Gazette S125, published on 18 August 1999 which states that management of waste ASS must be in accordance with the current best practice or any best practice environment management guidelines approved by the Authority.

The ASS Management Protocol was prepared with consideration of the following legislation and guidelines:

Environment Protection Act 1970

Environment Protection (Industrial Waste Resource) Regulations 2009

Industrial Waste Management Policy (Waste Acid Sulfate Soils)

EPA Victoria Publication IWRG655.1: Acid Sulfate Soil and Rock (July 2009)

Victorian Best Practice Guidelines for Assessing and Managing Coastal Acid Sulfate Soil (CASS BPMG, 2010).

National Acid Sulfate Soil Sampling and Identification Methods Manual, 2018

National Acid Sulfate Soil Identification and Laboratory Methods Manual, 2018

Australian Standards 4969.

2.0 Site overview

The information contained within this section has been extracted from the EES Technical Report E: Contamination and acid sulfate soils, EES Technical Report D: Groundwater, EES Technical Report C: Surface water and various information sources referenced within that document.

2.1 Site Description

A description of the Project area is provided in the Pipeline Works EMP.

2.2 Topography and surface water

The Project is located within the Western Port catchment and a large portion of Western Port is listed as a Ramsar Site of international significance, supporting a diversity of plants, animals and ecosystems, including several unique and threatened species, four marine national parks, large tracts of mangroves and seagrasses (Sharp et al., 2013).

The Western Port catchment varies from the hilly regions near the Bunyip State Park and Strzelecki Ranges to the low lying, flat to undulating terrain of the former Koo Wee Rup swamp with surface water draining from these topographic highs to Western Port.

The Project area includes coastal floodplains in the lower reaches of the catchment where the relief is mostly low lying and generally flat to gently undulating. The ground surface elevation ranges from approximately one to two metres above sea level in the southern portion to 10 – 25 metres above sea level over the northern portion, where the gently sloping topography grades up to the north.

A large portion of the Western Port catchment where the Pipeline Works will be located has been substantially cleared of native vegetation and is now predominantly used for farming. The pipeline will traverse coastal floodplains adjoining Western Port. The local hydrology of part of the catchment was








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substantially altered in the 1800s when creeks were modified to drain the Koo Wee Rup Swamp. Large open drains were excavated, and creeks increased in size to drain the swamp.

The pipeline alignment is contained within the Western Port catchment which includes a number of significant waterways that discharge to Western Port. Assessment undertaken as part of the EES Technical Report C: Surface water indicates that the proposed pipeline alignment crosses 64 waterways, swales and surface drains. The location of each waterway crossing is indicated on pipeline alignment plans provided in Appendix B of the EES Technical Report C: Surface water.

Desktop review of water quality monitoring for waterways crossed by the pipeline alignment, where water quality data is available indicates that that waterways in the catchment for the Pipeline Works, including more substantial waterways such as Cardinia Creek, are in poor condition and under considerable stress, while other waterways in the lower catchment are under severe stress.

Refer to the of the EES Technical Report C: Surface water for further information.

2.3 Regional geology and hydrogeology

The Project is located within Western Port Basin, which is a relatively shallow, structurally controlled sedimentary basin consisting of sediments and volcanic flows. The western side of the Basin coincides with the Clyde Monocline-Tyabb Fault System, and the eastern extent is controlled by the Heath Hill Fault. Basin sediments pinch out to the north against uplifted basement (SRW, 2010), and extend offshore to the south.

The sediments and volcanic flows of the basin form a multilayered aquifer system, which is dominated by a Tertiary Age sedimentary sequence that thickens to approximately 200 meters in the Koo Wee Rup area, and pinches out along Basin margins.

The Tertiary Age sediments are overlain by a relatively thin veneer of Quaternary sediments, including coastal and inland dune deposits, swamp and lake deposits and alluvial deposits; although these sediments thicken to between 10 and 50 meters in the Koo Wee Rup area.

A generalised description of the local geology encountered during site investigations is provided in Table 1Table 1 and the outcropping units in the study area are shown in Figure A1, Appendix AAppendix A. The geology encountered was consistent with the Geological Survey of Victoria Queenscliffe SJ 55-9 1:250,000 map (VandenBerg, A.H.M., 1997).

Table 1 Generalised local geology

Approximate Depth (mbgl)

Lithology / Formation General Lithology Encountered

0.0 – 0.2 FILL and/or Sandy CLAY Brown, FILL – minor reworked soils

0.0 – 1.0 Northern half: alluvial sediments, swamp lake deposit Southern half: primarily Brighton Group

Clayey SAND to CLAY, brown becoming grey, high to low plasticity

0.1 – 2.5 Sandy CLAY to CLAY; brown to grey, high to low plasticity

Regional groundwater flow is generally from the Basin margins towards Western Port. The presence of shallow aquitards, surface water features and groundwater extraction locally affect depths to groundwater. The groundwater table across the Basin will generally be a subdued version of topography, with the depth to groundwater increasing beneath topographical highs and shallow groundwater in the lower reaches of the Basin.

There is no long-term groundwater level data available and therefore the seasonal water level fluctuations are unknown. However, it is typical in shallow aquifers to have seasonal fluctuations of 0.5 to 2 meters. Water levels tend to be shallowest in late winter and spring, and deepest in late summer. Longer term fluctuations also occur due to changes in climate e.g. drought periods.








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A total of 26 groundwater wells were installed as part of EES site investigations. Drilling and installation of groundwater monitoring wells were completed between 3 December 2018 and 11 January 2019, and the subsequent gauging, sampling, and laboratory analysis was completed between 23 January 2019 and 30 January 2019.

Groundwater levels, field sampling parameters and groundwater quality laboratory analytical results are provided in Table B1 – B3, Appendix BAppendix B.

Refer to the EES Technical Report E: Contamination and acid sulfate soils and Technical Report D: Groundwater for further information.

3.0 CASS occurrence

Soil sampling program undertaken as part of the EES Technical Report E: Contamination and acid sulfate soils between 29 November 2018 and 26 April 2019 identified the presence of ASS throughout the Project area for the Pipeline Works. Net acidity exceeding the ‘Action Criteria’ of 0.03%S for disturbance exceeding 1,000 tonnes (BPMG, 2010) was exceeded in 72 soil samples of total 172 samples, with net acidity ranging between 0.02%S and 0.18%S and calculated liming rates to neutralise the calculated net acidity ranging between 1 kg CaCO3/tonne and 8 kg CaCO3/tonne. PASS was identified at the following sampling locations between KP17.8 and KP36:

KP17.8 – MW09 at depth of 3.0 metres below ground level (mbgl)

KP19.3 – MW10 at depth of 3.0 mbgl

KP32.5 – BH207 at depth of 0.5 mbgl

KP32.8 – BH209 at depth of 0.5 mbgl1

KP36 – BH34 at depth of 2.0 mbgl1

It is noted that sample point frequency does not comply with the recommendation made in Table 1 of Victorian EPA publication IWRG655.1: Acid Sulfate Soil and Rock which specifies sampling at 100 metre intervals for a pipeline, except at the ASS targeted sampling locations (defined in the ASRIS as an area with high probability of occurrence of ASS, shown in Figure A2, Appendix AAppendix A). However, the distribution of ASS throughout the Project area would suggest that this is not required, other than to calculate or refine liming rates, and that all soils be managed as ASS (AASS or PASS) in accordance with Victorian Best Practice Guidelines for Assessing and Managing Coastal Acid Sulfate Soils (CASS BPMG) (2010).

The ASS samples locations, net acidity and liming rate for each sample are shown in Figure A3, Appendix AAppendix A. Tabulated results are provided in Table B4, Appendix BAppendix B.

4.0 Project description

The Project description including the construction methodology, operation and maintenance is provided in the Pipeline Works EMP.

5.0 CASS management strategy

The soil assessment undertaken identified that all soils should be managed to mitigate acidic or PASS. The strategy outlined below is based on the proposed construction methodology.

Clearing of vegetation and topsoil (approximately 100 millimetres in thickness) within the construction right of way (ROW) is required to provide a safe and efficient area for construction activities. This activity may occur up to several months before the trench excavation, whereas the remainder of the trench (“Trench Spoil”) is proposed to be excavated and backfilled within the duration specified in

1 Conservatively classified as PASS. Samples were analysed using the SPOCAS method for QA/QC data validation purposes.








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Section 5.2.3.1. Due to the different timeframe / methodologies and risk profile, separate management strategies are proposed for the topsoil and the trench spoil.

5.1 Topsoil

The field investigation indicated that the surface soils (between 0.0 and 0.2 mbgl) within the Project area contain existing acidity, with pH (CaCl2) ranging between 4.1 and 7.6 pH units and approximately 60 per cent of topsoil samples were below pH 5.0 (from 60 soil samples). It is not possible based on available data to identify whether the soils are simply acidic or are AASS. Laboratory derived data for the sub-soils indicate the presence of existing acidic soils, where acidity is potentially from sources other than inorganic sulfides.

Note that the CASS BPMG (2010) is silent on the management of topsoil under these conditions and therefore we have referred to information presented in the National Acid Sulfate Soils Guidance (Sullivan et al, 2018), regarding naturally acidic topsoil.

Naturally occurring acidic soils are not considered an environmental hazard and indeed are usually part of acidophilic ecosystems, whose health depends on maintaining an acidic environment. Liming of naturally acidic ecosystems could lead to unnaturally alkaline environments resulting in severe ecological damage to the acidophilic organisms that relied on the acidic nature of these ecosystems (Sullivan et al, 2018). As a result, the potential soil acidity risks associated with the topsoil stockpile should be managed by regular monitoring (for pH) of surface water runoff following rainfall, adjacent to water courses and sensitive receptors. Runoff from the topsoil stockpile should be managed in accordance with the mitigation measures for surface water specified in the Pipeline Works EMP; and neutralisation (based on liming rates given in Section 5.2.4) should be undertaken if acceptable pH levels are exceeded. Alternatively, the topsoil can be sampled in accordance with CASS BPMG (2010) and the risk reassessed.

5.2 Trench spoil

The following are ASS management strategies numbered in order of priority, as prescribed by the CASS BPMG (2010). 1. Avoid disturbance.

2. Minimise disturbance – Excavate the smallest quantity of soil possible, avoid dewatering where possible or reduce extent and timeframe of dewatering, creation of small stockpiles etc.

3. Prevent oxidation – Stage Project activities to reduce stockpile duration, consider covering stockpiles with high density polyethylene (HDPE) if extended exposure required.

4. Treat to reduce or neutralise acidity –Treat stockpiles with lime or use guard layers in conjunction with prevention techniques. Treatment may not be required depending on minimisation and prevention approaches adopted.

5. Offsite reuse or disposal - Dispose offsite at an EPA Victoria approved facility.

The preferred management option for the trench spoil during the pipeline construction is to prevent oxidation of ASS and minimise exposure upon excavation.

5.2.1 Avoid disturbance

The desirable management approach to deal with ASS soils is to avoid disturbance wherever possible. However, there is limited opportunity to do this as the Project is bound by engineering and spatial constraints.

5.2.2 Minimise disturbance

Where disturbance of ASS is unavoidable, The Project will minimise the amount of ASS disturbance by preparing a detailed soil excavation staging strategy that include:

Staging of disturbance such that the potential effects on soils disturbed at any one time can be effectively managed.








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Staging of disturbance to avoid activities that result in large scale or long-term fluctuation in groundwater levels. Careful planning of disturbance to minimise the extent or length of time groundwater table is raised or lowered.

5.2.3 Prevent oxidation

5.2.3.1 Stage Projects

In addition to minimising the amount of ASS disturbance, the Project will minimise the duration of exposure of disturbed sub soil material in order to prevent generation and transport of acid. Staging the excavation program to minimise the amount of time that ASS is exposed to the atmosphere (including rainfall and seeping perched waters (if any)).

The soil excavation staging strategy (described in Section 5.2.2) will include the time period over which soils may be temporarily stockpiled, as recommended by the CASS BPMG (2010), presented in Table 2Table 2.

Table 2 Suggested short-term stockpiling durations based on soil texture (after Dear et al., 2002)

Type of material (McDonald et al., 1990)

Approx. clay content % Duration of stockpile

Coarse (sands to loamy sands) ≤ 5 Overnight (18 hours)

Medium (sandy loams to light clays) 5–40 2.5 days (70 hours)

Fine (medium to heavy clays and silty clays. ≥ 40 5 days (140 hours)

Some control measures during temporary stockpiling include:

Construction works during wet weather should be avoided unless conditions are such that surface water issues can be managed e.g. covering the stockpile and directing runoff that has the potential to be impacted by the stockpile material into the open trench (where practicable).

Soil stockpiles will be established such that it does not exceed two metres in height and safe batter slopes are maintained at all times.

5.2.4 Treat to reduce or neutralise acidity

If soils are to be stockpiled longer than the recommended time period for short-term stockpiling durations (as described in Section 5.2.3.1), then the excavated spoil will be neutralised using a liming agent and verified prior to reuse (if needed).

Neutralisation of ASS involves mixing of finely crushed (predominantly








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pad may not be needed. However, in case, of larger volumes (e.g. greater 250 cubic metres), a temporary ASS treatment area will need to be established prior to commencing excavation works.

The treatment area will be sized and constructed to ensure there is sufficient area to accommodate the treatment pad footprint, stockpiles of treated material and soils requiring treatment, while being able to efficiently accommodate the machinery and associated support equipment.

The location of the temporary treatment area will consider the available space within the 30-metre-wide pipeline construction ROW, staging of excavations and broader construction timing, and health and safety requirements. Neutralisation of ASS will be conducted on a temporary treatment pad (if required) within the designated treatment area.

5.2.4.2 Temporary Treatment Pad

The treatment pad (if required) will collect and isolate the leachate from the surrounding environment. The treatment pad will be appropriately designed to isolate and contain potential leachates generated from the surrounding environment, consisting of:

A low permeability base (below a guard layer of aglime) such as compacted clayey soil material (greater than 0.1 metre thick), a concrete slab, layer of bitumen or HDPE sheeting to reduce the infiltration of leachate to the soil and groundwater. The base layer will be slightly sloped to prevent leachate from pooling within the treatment pad area.

A guard layer of aglime will be spread onto the base layer of the treatment pad, before the placement of soils, at a rate of 5 kilograms fine aglime per square metre per vertical metre of sediment. This will reduce the risk by neutralising acidic leachate generated in the treatment stockpile that are not neutralised during the treatment process. Since the guard layer is likely to be removed with the treated soil, the guard layer will be reapplied as necessary.

Appropriate leachate collection system and containment bund will be used to contain stormwater runoff and leachates. Stormwater run-on will be diverted away from the treatment pad using sandbags, shallow diversion/catch drains or similar (if required).

Leachates and runoff collected and contained within the treatment pad area will be appropriately treated (if required) prior to discharge

5.2.4.3 Soil Neutralisation Procedure

The following soil neutralisation procedure should be used:

ASS materials identified will always be kept separate from other soils such as topsoil (wherever possible) to reduce the volume of material requiring neutralisation/treatment.

Neutralisation will be carried out as soon as practically possible and will be conducted by mechanical means (e.g. mechanical tilling or bucket blending methods) to achieve uniform blending, as far as practical, of the ASS with liming agents.

All necessary Personal Protective Equipment (PPE) and controls will be used to ensure adequate measures, associated with lime neutralising activities, are implemented to minimise dust emissions, inhalation and direct contact with fine aglime. As a minimum, safety glasses to protect the eyes, nitrile gloves (when required) and long sleeve pants and shirt to reduce direct skin contact, and an approved face mask to prevent inhalation of dust (minimum AS/NZS 1716 Class P2 face mask for casual exposure).

Soil stockpiles will be established such that it does not exceed two metres in height and safe batter slopes are maintained at all times. If wet weather is forecasted, un-neutralised stockpiles should be covered and should have means to collect runoff water before releasing in the environment.

ASS will be fully treated or neutralised with fine aglime prior to reuse onsite within the Project boundary.

Neutralisation will also be used as a contingency plan to address actions to be undertaken where the management and mitigation framework in this document are not met, such as if soils are to be








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stockpiled longer than the recommended time period for short-term stockpiling durations (as described in Section 5.2.3.1) or additional ASS are identified on site that are inconsistent with existing sampling, additional sampling for laboratory characterisation and subsequent appropriate liming should be considered (Sections 3.0 and 5.2.4.4).

5.2.4.4 Liming Rate

Sufficient aglime is required to ensure all existing acidity that may be present and potential acidity that could be generated from complete oxidation of the sulfides over time is neutralised. The calculated liming rate for each sample, completed as part of the EES Technical Report E: Contamination and acid sulfate soils, are shown in Figure A3, Appendix AAppendix A and tabulated in Table B4, Appendix BAppendix B. Table 3Table 3 shows the preliminary nominal liming rates required for soil material excavated from the site. Liming rates have been determined using the highest net acidity. Liming rates are relevant to the respective soil type and depth encountered during the investigation. Any unexpected soils identified not consistent with the existing sampling, additional sampling for laboratory characterisation and subsequent appropriate liming is to be considered.



Acid Sulfate Soils Management Protocol – Pipeline Works ASS Management Protocol – Pipeline Works ASS Management Protocol




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Table 3 Liming Rate

Chainage Apparent Distance (m)

Borehole Soil Type Depth (mbgl)

Net Acidity (%S)

Liming Rate (kg aglime/tonne)*

KP0.0 – 1.1 1,100 CPT002_BH101 to CPT006_MW01

Medium plasticity Clays 0.0 – 1.5 0.04 2

Medium plasticity Clays 1.5 – 2.5 0.09 4

KP1.1 – 7.7 6,600 CPT006_MW01 to CPT022W_MW05

Silty Clays to low plasticity clays 0.0 – 1.5 0.04 2

Gravelly silt, low to high plasticity clays 1.5 – 3.0 0.07 3

KP7.7 – 11.4 3,700 CPT022W_MW05 to CPT032_BH11

Medium plasticity Clay 0.0 – 0.5 0.09 4

Sandy clay to high plasticity clay 0.5 – 1.0 0.05 3

KP11.4 – 15.0 3,600 CPT032_BH11 to CPT045_GW05

Gravelly sand, sandy silt, sand, sandy clay, clayey sand

0.0 – 4.0 0.02 1

KP15.0 – 17.7 2,700 CPT045_GW05 to CPT049B_BH17

Sand, clays 0.0 – 2.0 0.06 3

KP17.7 – 19.5 1,800 CPT049B_BH17 to CPT055_MW10

High plasticity clay 0.0 – 0.5 0.02 1

Sandy clay 0.5 – 3.0 0.18 8

KP19.5 – 25.1 5,600 CPT055_MW10 to CPT067_BH24

Sandy clay, low to high plasticity clays 0.0 – 0.5 0.10 5

Sandy clay 0.5 – 3.0 0.06 3

KP25.1 – 32.3 7,200 CPT067_BH24 to CPT084_BH206

sand, low to high plasticity clays 0.0 – 2.0 0.03 1

KP32.3 – 32.6 300 CPT084_BH206 to CPT084_BH210

High plasticity clays

0.0 – 0.5 0.04 3

0.5 – 2.0 0.02 1

KP32.6 – 33.0 400 CPT084_BH210 to CPT084_BH214


0.0 – 2.0 0.03 1

KP33.0 – 33.2 200 CPT084_BH214 to CPT084_BH217


0.0 – 1.5 0.06 3

KP33.2 – 36.1

2,900 CPT084_BH217 to CPT093_BH225

Medium plasticity clay 0.0 – 0.2 0.04 2


KP36.1 – 36.4 300 CPT093_BH225 to CPT094_BH35

High plasticity clay

0.0 – 0.5 0.06 3

0.5 – 1.5 0.05 2

KP36.4 – 39.8 3,400 Low plasticity clay 0.0 – 0.5 0.09 4



Acid Sulfate Soils Management Protocol – Pipeline Works ASS Management Protocol – Pipeline Works ASS Management Protocol




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Chainage Apparent Distance (m)

Borehole Soil Type Depth (mbgl)

Net Acidity (%S)

Liming Rate (kg aglime/tonne)*

CPT094_BH35 to CPT104_BH38


KP39.8 – 45.4 5,600 CPT104_BH38 to CPT117_BH44

Silty clay, High plasticity clay

0.0 – 0.2 0.13 6

0.2 – 1.0 0.06 3

1.0 – 2.0 0.05 2

KP45.4 – 56.5 11,100 CPT117_BH44 to CPT142_BH54

Clayey sand, sandy clay 0.0 – 1.5 0.05 2

Low to high plasticity clay 1.5 – 3.0 0.02 1

*Note: Based on minimum safety factor of 1.5. It needs to be recalculated in the field based on wet bulk density and neutralising value of the aglime

mbgl: meters below ground level

Soil type description logged to the Australian Standard AS 1726 Geotechnical Site Investigations








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As noted in Section 3.0, the sample point frequency does not comply with the recommendation made in Table 1 of Victorian EPA publication IWRG655.1: Acid Sulfate Soil and Rock which specifies sampling at 100 metre intervals for a pipeline, except at the ASS targeted sampling locations (defined in the ASRIS as an area with high probability of occurrence of ASS, shown in Figure A2, Appendix AAppendix A). However, the distribution of ASS throughout the Project area would suggest that this is not required, other than to calculate or refine liming rates, and that all soils be managed as AASS or PASS in accordance with CASS BPMG (2010).

If unknown material (such as grey moist clays or material with yellow mottling are identified), further testing of in-situ soil material or stockpile may be carried out during bulk excavation. In the case of additional sampling, the required aglime application rate will be calculated using the following:

Liming Rate (𝑘𝑔 𝑎𝑔𝑙𝑖𝑚𝑒/𝑚3) = 𝑁𝑒𝑡 𝐴𝑐𝑖𝑑𝑖𝑡𝑦 (%𝑆) ×623.7

19.98× 𝑊𝑒𝑡 𝐵𝑢𝑙𝑘 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 (𝑡 𝑚3) ×

100

𝑁𝑉×⁄ 𝑆𝐹 [1]

Where:

NV = neutralising value of the aglime being used and represents the purity or per cent of CaCO3 in the limestone. Unless otherwise known, an initial NV value of 93% will be used considering that agricultural limestone usually contains impurities.

Wet bulk density = 1.7 t/m3 if the soil bulk density is unknown.

SF = safety factor (= 1.5) because aglime has a low solubility and hence a low reactivity, and in most situations will not be fully mixed with the soil regardless of the method used. (Dear et al, 2014)

5.2.4.5 Verification Testing and Monitoring

The neutralisation of ASS material needs to be verified before re-use. For all the neutralised material, verification samples will be collected from each treated lot. The samples collected over the full thickness of the treated lot, will be formed by compositing materials from three randomly selected locations across the lot/stockpile. Soil sampling for verification (and assessment) purpose will be conducted in accordance with Dear et al. (2014) as soon as practically possible within 42 hours (i.e. 2 nights). Large gravels (greater than 2 millimetres), fragments of wood, charcoal and stones need to be noted before being removed from the samples in the field.

Samples will be collected in laboratory supplied ASS bags, stored on ice in a cool box and submitted to a laboratory on the day of collection (with chain of custody (COC) documentation) that is accredited by the National Association of Testing Authorities (NATA) for ASS analysis. The Chromium reducible sulfur (CRS) suite will be conducted on each sample to confirm net acidity by Acid Base Accounting.

As per Dear et al 2014, the following performance criteria must all be met for soil that has been treated using neutralisation:

The neutralising capacity of the treated soil must exceed the existing plus potential acidity of the soil by at least a safety factor of 1.5.

Post-neutralisation, the soil pH (pHKCl) is to be greater than 6.5

No single sample shall exceed a net acidity of 0.03 %S.

Excess neutralising agent should stay within the treated soil until all acid generation reactions are complete and the soil has no further capacity to generate acidity.

5.2.4.6 Characterisation of Suspected Acid Sulfate Soils

Neutralisation will also be used as a contingency plan to address excavated soils that are not

representative of the soil testing (see Section 3.0). That is, if the below indicators of ASS are identified

at the site, neutralisation should be undertaken. Indicators include:

Dark coloured wet soft clays (refer to Plate 1Plate 1)

Jarosite (yellow staining) or other aluminium sulfate minerals become apparent (refer to Plate 1Plate 1)

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Iron hydroxide (reddish staining) becomes apparent

Hydrogen sulfide (rotten egg) smell

Additional sampling and analysis indicate concentrations of reduced inorganic sulfur is greater than 0.03%.

Plate 1 Dark clays (left) and yellow mottling (right) indicating presence of acid sulfate soils

Where suspected ASS is encountered, this material must be excavated separately and segregated from non-ASS materials. An experienced ASS practitioner swil attend site to provide additional guidance on suspected ASS on as required basis. Where suspected ASS is encountered a field test (pHF and pHFOX) will be conducted to provide an initial assessment of the materials. Field screening tests (described in Appendix CAppendix C) will be conducted at a minimum rate of one per 250 m3 of suspected ASS material encountered. Confirmatory tests will comprise sample analysis for the CRS Suite of tests. Materials returning net acidity less than 0.03%S will be removed from the stockpile area and used as fill without further acid sulfate management. Where net acidity greater than 0.03%S (with reduced inorganic sulfur greater than 0.03%) is found, the materials will be treated using aglime as described in Section 5.2.4.3.

5.2.5 Offsite reuse or disposal

There is a possibility that the excavated material is considered to be unsuitable for reuse on-site from a geotechnical and contamination perspective. As such, any excess acidic spoil material of this nature would be transferred off-site to a nominated landfill with a licence to accept such material.

Potential controls during transfer of acidic spoil material from site include:

Implementation of a materials handling and tracking procedure.

Transfer of material to the facility within the time period over which soils may be temporarily stockpiled as recommended by the CASS BPMG (2010) (refer to Section 5.2.3), keeping the stockpiles covered to avoid runoff.

Transfer of soil in covered trucks.

5.2.6 Water management

No active dewatering of groundwater is being proposed as part of construction activities. However, field investigation undertaken as part of the EES impact assessment indicated that trenching may encountered groundwater in some sections of the pipeline alignment. To ensure that pipeline construction meets applicable standards, the trench may need to be dewatered to remove any water which has collected during the time it has been open. The Pipeline Works will discharge non-contaminated acidic and/or brackish groundwater/trench water from the open trenches and bell holes to adjacent land (with permission/approval from relevant landholder (where appropriate). Dewatering activities will be managed in accordance with SEPP (Waters) and the Pipeline Works EMP.

The following are management measures for the trench water:

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Dewatering activities will adopt the management and mitigation practices outlined in the “National Acid Sulfate Soils Guidance: Guidance for the dewatering of acid sulfate soil in shallow groundwater environments”

Runoff that has the potential to be impacted by stockpile material should be directed into the open trench (where practicable).

Minimise activation of PASS by minimising duration (less than seven days) and extent of dewatering activities, such as dewatering immediately prior to installation of pipe and minimise the time that trench sections and bell holes are open. If the duration of dewatering exceeds 7 days and the radial extent of the groundwater cone of depression is greater than 50 metres, the requirements of Dewatering Management Level 2 will be implemented in line with the national guidelines.

Water collected from within excavated trenches should be collected and treated if turbidity exceeds EPA requirements prior to discharging. Refer to the relevant section in the Pipeline Works EMP.

Water should be tested for pH and salinity prior to discharge to land. pH should be between 4 and 9, and salinity should not exceed 6,000µS/cm.

Discharge of water to land should avoid soil erosion or sedimentation of land or water. Sediment control devices to remove suspended solids and dissipate flow should be used where required.

Water should not be discharged to waterways or into stormwater drains without approval from relevant authorities.

Water that cannot be treated to meet the relevant discharge criteria should be disposed to an EPA Victoria licensed facility.

Relevant landholder(s) and water authorities should be consulted, and permission obtained prior to discharge to land.

Discharge to land should not occur within 50 metres of watercourses.

Discharge should be to low gradient, stable, grassed areas and be undertaken in accordance with landholder requirements and through “irrigation type” systems to prevent scour or erosion. Visual monitoring during land discharge should be undertaken to ensure water does not enter existing waterways.

Contaminated water should be managed in accordance with mitigation measures described in the Pipeline Works EMP. The following are areas where contaminated groundwater has been identified and discharge to land must not occur:

- Between KP14.0 and KP14.3, adjacent to the former Tyabb landfill.

- Between KP7.3 and KP7.9. An intrusive groundwater investigation must be undertaken in the area prior to commencing pipeline construction, to confirm presence or absence of contaminated groundwater within the area, due to historical and existing land uses.

Where dewatering is required for horizontal thrust bore bell holes where acid sulfate soils are present and groundwater is intersected, the requirements of Dewatering Management Level 1 of the national guidelines will be implemented, including:

━ Installation of a groundwater monitoring well at approximately 10 metres from the thrust bore

bell hole and dewatering is required during construction.

━ Water table level monitoring daily during the dewatering operation and compare against the

estimated drawdown and/or radial extent of the groundwater cone of depression to ensure

that the actual drawdown and/or radial extent of the groundwater cone of depression is not

more than that predicted from calculations.

━ Measurement of the groundwater pH every day in the groundwater monitoring well and the

excavation inflow during the dewatering operation to assess for groundwater acidification.








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Cessation of dewatering and undertake risk assessment to determine appropriate remediation option(s) if the results of groundwater and/or dewatering effluent monitoring indicate deterioration in groundwater quality e.g. groundwater pH is less than 5.5 pH units,

5.2.6.1 Treatment of Acidic waters

As acidic leachate or groundwater seepage into trenches normally contains or may contain many ions capable of producing acidity by hydrolysis (e.g. Fe3+, Al3+), a water sample should be taken for laboratory analyses (for measurement of titratable acidity) to more accurately determine lime requirements.

If laboratory analysis is constraint by time due to the adopted ASS management strategy (refer to Sections 5.2.2 and 5.2.3), and no other means of estimating the amount of neutralising agent is available, the amount required to neutralise the trench water can be calculated by firstly measuring the current pH of the excavation pit water with a recently calibrated pH meter. The desired pH is usually between 6.5 and 8.5 (pH 7 is normally targeted).

The rate of application of neutralising agent will vary with the solubility, the fineness of the neutralising agent, the application technique and the pH of the water. Table 4Table 42 provides a general guide, for minimum quantities of pure aglime, hydrated lime and sodium bicarbonate needed to treat impounded water of 1 megalitre (1,000 cubic metres) capacity.

Table 4 General guide to neutralise 1ML of acidic leachate

Current Water pH Aglime (kg pure CaCO2)

Hydrated Lime ((kg pure CaOH)

Sodium Bicarbonate (kg pure NaHCO2)

0.5 15,824 11,716 26,563

1.0 5,004 3,705 8,390

1.5 1,600 1,185 2,686

2.0 500 370 839

2.5 160 118 269

3.0 50 37 84

3.5 16 12 27

4.0 5 4 8.4

4.5 1.6 1.18 2.69

5.0 0.5 0.37 0.84

5.5 0.16 0.12 0.27

6.0 0.05 0.037 0.08

6.5 0.016 0.012 0.027

Notes:

The calculations in this table assume low saline water acidified by hydrogen ions (H+) and does not take into

account the considerable buffering capacity or acid producing reactions of some acid salts and soluble

species of aluminium and iron.

To more accurately calculate the amount of commercial product required, the weight of neutralising agent

from the table should be multiplied by a purity factor (100/ Neutralising Value for aglime) or (148/

Neutralising Value for hydrated lime).

2 Table 5, section 10.15, Planning and Managing Development involving Acid Sulfate Soils, Department of Natural Resources and Mines, Queensland Government, 2002








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If neutralising substantial quantities of ASS leachate, full laboratory analysis of the water will be necessary to

adequately estimate the amount of neutralising material required.

Hydrated lime is more soluble than aglime and hence more suited to water treatment. However, it has a

higher pH; as such, incremental addition and thorough mixing is needed to prevent overshooting the desired

pH. The water pH should be checked regularly after thorough mixing and allowing sufficient time for

equilibration before further addition of neutralising product.

5.2.6.2 Training requirements for construction personnel

The requirements of this document will be communicated through toolbox talks and pre-start meetings, with the information relevant to the day’s activities being re-iterated to ensure that ASS is managed in accordance with this ASS Management Protocol.

Specifically, all relevant site-based personnel must be trained on the requirements of the ASS management procedure including the recommended time period over which soils may be temporarily stockpiled before treatment commences as recommended by the CASS BPMG (2010) (refer to Section 5.2.3).

If unexpected ASS is encountered a detailed ASS assessment must be undertaken by an appropriately qualified and experienced practitioner in line with the requirements of the CASS BPMG (2010). A suitably qualified person is a professionally accredited soil scientist or a person with five or more years recognised experience in ASS assessment and management.

ASS field indicators are provided Appendix DAppendix D.

5.2.7 Contingency plan

Adaptive management methods will be used to address actions to be undertaken where the management and mitigation measures in this document are not met. Contingency actions for the management of ASS during the construction phase include:

In the event that the duration of the earthworks is extended (due to unforeseen circumstances), a reassessment of the risk and management strategies must be undertaken, updated and implemented (if required).

Appropriate steps must be taken to minimise infiltration of water into the stockpiles as far as practically possible (e.g. staging the works so that manageable amounts of spoil are generated at one point, covering with durable plastic sheeting) prior to expected and during unforeseen rainfall events.

In the event of emergency situation (e.g. unforeseen severe weather) or the material cannot be fully treated within the recommended short-term stockpiling durations (refer to Section 5.2.3), fine aglime at a rate of 5 kilograms fine aglime per square metre per vertical metre of stockpile will be spread over the surface of excavated ASS. This will reduce risk and limit/control the generation of acidity in the first instance as a contingency measure.

Appropriate steps should be taken to minimise infiltration of water into any temporary ASS stockpiles or the ASS loads in the trucks as far as practical possible (e.g. use of durable plastic sheeting) prior to expected and during unforeseen rainfall events, minimising water spraying). The plastic sheeting will be suitably anchored to the ground surface.

If any soils are encountered during excavation works that are not representative of the soils previously identified, laboratory tests in accordance with the CASS BPMG (2010) and the National ASS guidance (2018) will be completed to identify ASS horizons and evaluate the amount of existing and potential acidity.

For onsite treated ASS (if undertaken), if verification testing of aglime treated ASS indicate the performance criteria has not been met, the material will remain within the treatment area and be re-treated with sufficient aglime to achieve the performance criteria (refer to Section 7.0 prior to reuse.








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6.0 Monitoring program

During the construction at Pipeline Works, the following monitoring regime shall be undertaken with respect to ASS. Monitoring will be carried out by an appropriately qualified person, using calibrated equipment on samples that are representative of the discharge or background.

6.1.1 Trench water

Water should be tested for pH and salinity prior to discharge to land. pH should be between 4 and 9, and salinity should not exceed 6,000 µS/cm.

Waters not meeting required performance indicators (refer to the Pipeline Works EMP) will be treated until performance indicators are met prior to discharge to land.

7.0 Performance criteria

7.1.1 Soil neutralisation

Onsite soil treatment criteria are provided as a contingency and included in Section 5.2.4.5.

Soil that has been treated by neutralisation techniques and has not met these criteria will be re-treated and re-tested until the Performance Criteria (provided in Section 5.2.4.5) or are met.

8.0 Timing of environmental activities

Construction works should not occur during wet months unless conditions are such that land degradation and surface water management problems can be avoided, or appropriate mitigation measures implemented.

If off-site disposal is required, licensed disposal facilities will be contacted prior to the commencement of works to confirm the volumes and timeframes around the works to ensure that the receiving facilities have capacity at the time of planned excavation works.

Prior to the commencement of dewatering activities, the baseline pH level, salinity and total dissolved solids (TDS) of trench water (as appropriate) in the area of the works will need to be established to allow for effective ongoing monitoring throughout the duration of the works.

9.0 Reporting

Records should be kept on site in relation to ASS management activities and any contingency actions that are implemented during the construction phase of the Project, including:

• Records of any trench water monitoring.

• Photographic evidence of water quality in the trench monitoring locations

• Records of aglime quantities used to treat excavated ASS (if encountered) and acidic water to consolidate the bulk aglime brought on to site against the amount used.

• Soil excavation volumes, treatment volumes (if required) will be recorded daily during earthworks.

• Records of any laboratory testing for soils and water samples.

10.0 Consultation and approvals

EPA Victoria was consulted on 19 August 2019. It was agreed that this ASS management protocol will be developed and included in the Pipeline Works EMP, which will be approved in accordance with the Pipeline Act 2005, in consultation with EPA Victoria.








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11.0 References

Dear, S. E., Ahern, C. R., O'Brien, L. E., Dobos, S. K., McElnea, A. E., Moore, N. G., & Watling, K. M. (2014). Queensland Acid Sulfate Soil Technical Manual: Soil Management Guidelines (p. 3). Brisbane: Department of Science, Information Technology, Innovation and the Arts, Queensland Government.

EPA Victoria (2009). Acid Sulfate Soil and Rock. Publication IWRG655.1. Environmental Protection Authority, Victoria.

Sullivan, L, Ward, N, Toppler, N and Lancaster, G (2018). National Acid Sulfate Soils guidance: National acid sulfate soils sampling and identification methods manual, Department of Agriculture and Water Resources, Canberra ACT. CC BY 4.0.

Victorian Coastal Acid Sulfate Soils Implementation Committee. & Price, Rebecca. & Victoria. Department of Sustainability and Environment (2010). Victoria's best practice guidelines for assessing and managing coastal acid sulfate soils. Melbourne. Dept. of Sustainability and Environment.








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AAppendix A

Figures








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Appendix A Figures








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BAppendix B

Tables








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Appendix B Tables








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CAppendix C

Field Screening Testing and Interpretations








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Appendix C Field Screening Testing and Interpretations

Method Description

The pH field (pHF) and pH peroxide (pHFOX) tests also called as screening tests provide a quick

indication of presence or absence of existing and potential acidity in soils. The tests are purely

qualitative and do not give a quantitative measure of the amount of acidity that has been or could be

produced through the oxidation process. This section has been referenced from National Acid Sulfate

Soil Sampling and Identification methods manual, Sullivan et al., 2018.

Equipment Needed

The following equipment is needed to conduct these tests in the field:

pH meter and electrode – charged and calibrated

Buffer solutions – pH 4 and pH 7

Laboratory grade 30% Hydrogen Peroxide stored appropriately

1M Hydrochloric acid to test for shell

Sodium hydroxide to raise pH of Hydrogen peroxide to pH 4.5 (if needed)

Deionised Water

Test tubes and/or plastic containers sufficient to hold 100 ml and rack

Gloves, paper towels, brushes and buckets for cleaning containers

Data recording sheets.

Procedure

The key steps are:

Calibrate pH meter as per manufacturer’s instructions

Measure pH of Deionised water and hydrogen peroxide

Remove approximately 1 teaspoon of soil from the profile. Place approximately half teaspoon of

soil into the pHf test tube and place half teaspoon of the soil into the pHfox test tube. It is important that these 2 sub-samples come from the same sample and that they are similar in characteristics

Add sufficient deionised water in one test tube to make a 1:5 soil water paste. Mix it carefully with wooden skewer and place the pH meter in it. Measure the pH of the soil water solution.

To the second test tube/ container, add few millilitres of 30% hydrogen peroxide sufficient to cover the soil and stir the mixture. Note the reaction of the soil using a reaction scale (given below)

Allow 5 to 10 min for any reactions to occur, do not leave unattended to ensure there is no cross contamination

If needed, keep on adding hydrogen peroxide (2-3 times) until the reaction has slowed (ensuring most sulphides have reacted).

Wait for soil peroxide mixture to cool before placing the pH electrode.

Reaction Scale

Reaction Rate Type of reaction

L Slight reaction

M Moderate reaction








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Reaction Rate Type of reaction

H High reaction

X Very vigorous reaction, gas evolution and

heat generation

Guidance on interpreting Field Screening

Tests:

A combination of three indicators is considered in arriving at a ‘positive field sulfide identification’ (i.e.

the presence of Potential Acid Sulfate Soils (PASS):

A reaction with hydrogen peroxide – the strength of the reaction with peroxide is a useful indicator but cannot be used alone. Organic matter, coffee rock and other soil constituents such as manganese oxides can also cause a reaction. Care should be exercised in interpreting a reaction on surface soils and high organic matter soils such as peats and coffee rock and some mangrove/estuarine muds and marine clays. This reaction should be rated, e.g. L = Low reaction, M = Medium reaction, H = High reaction, X = Extreme reaction, V = volcanic reaction.

The actual value of pHFOX. – if pHFOX is less than 3, and a significant reaction occurred, then it strongly indicates a PASS. The more the pHFOX drops below 3, the more positive the presence of inorganic sulfides.

A much lower pHFOX than field pHF – the lower the final pHFOX value and the greater the difference between the pHFOx compared to the pHF, the more indicative of the presence of PASS. This difference may not be as great if starting with an already very acid pHF (close to 4), but if the starting pH is neutral or alkaline then a larger change in pH should be expected. Where fine shell, coral or carbonate is present the change in pH may not be as large due to buffering. The ‘fizz test’ (effervescence with 1 M HCl) should be used to test for carbonates and shell. If these three factors, the final pHFOX value is the most conclusive.

The following interpretation will be adopted for field screening tests:

Strong Indicator of PASS – all three indicators present (pHFOX less than 3; M to H reaction, pHF – pHFOX less than 3)

Moderate Indicator of PASS – pHFOX greater than 3 and the remaining two indicators are positive

Low Indicator of PASS – pHfOX greater than 3 and one or none of the remaining indicators are positive

A pHF of less than 4 is likely to indicate the presence of AASS.

A sample with strong indicator of PASS need to be sent to laboratory for further analysis including

Chromium Reducible Sulfur (CRS) suite for net acidity and inorganic sulfur concentrations.








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DAppendix D

Acid sulfate soils field indicators








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Appendix D Acid sulfate soils field indicators

The following field indicators can assist in the identification of unexpected ASS encountered during the excavation works. If any of these indicators are observed outside of where ASS has been identified, a suitably qualified person will need to be engaged to conduct an assessment of the material as per the requirements of the CASS BPMG (2010).

Soil Type Indicators

Acid Sulfate Soil

(ASS)

Landscape Characteristics

dominance of mangroves, reeds, rushes, and other marine, estuarine or swamp-

tolerant vegetation

low lying areas, back swamps, scalded or bare areas in coastal estuaries and

floodplains

sulphurous smell after rain following a dry spell or when soil is disturbed

Actual Acid Sulfate

Soil (AASS)

Soil Characteristics

field soil pH test results ≤ 4.0

presence of shell with or without orange-yellow staining or coating

any jarositic (jarosite is a pale-yellow mineral deposit which can precipitate as pore

fillings and coatings on fissures) horizons or iron oxide mottling in auger holes or

recently dug surfaces. With a Fluctuating water table, jarosite may be found along

cracks and root channels in the soil. However, jarosite is not always found in actual

sulfate soils

jarosite present in surface encrustations or in any material dredged or excavated and

left exposed

Groundwater Characteristics

groundwater pH test results < 5.0

elevated dissolved sulfate and/or dissolved mass-based chloride-sulfate ratio

(Cl:SO4) < 4.0

Surface Water Characteristics

water pH < 5.5 in adjacent streams, drains or groundwater

unusually clear or milky blue-green drain water within or flowing from the area

(aluminium released by the acid sulfate soils acts as a flocculating agent)

extensive iron stains on any drain or pond surface, iron stained water or ochre

deposits

Potential Acid

Sulfate Soil (PASS)

Soil Characteristics

soil pH usually neutral but may be acidic when tested with the pHfox test

offensive sulphurous odour

waterlogged soils, soft muds (blue-grey or dark green-grey, soft, buttery soils) or

estuarine silty sands

mid to dark grey sands or bottom sediments of estuaries or dark grey tidal lakes

presence of shell

water characteristics

water pH usually neutral but may be acidic

Source: Victorian Best Practice Guidelines for Assessing and Managing Coastal Acid Sulfate (2010)

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