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Doc No. Document No
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Acid Sulfate Soils Management Protocol
Pipeline Works ASS Management Protocol
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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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ISO14001 AS/NZS4801 and OHSAS18001.
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reasonably be expected to make in accordance with sound
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some of which
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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
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consent of AECOM. AECOM undertakes no duty, nor accepts any
responsibility, to any
third party who may rely upon or use this document. This
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reasonably be expected to make in accordance with sound
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principles. AECOM may also have relied upon information provided
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may not have been verified. Subject to the above conditions,
this document may be transmitted, reproduced or disseminated only
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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
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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
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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
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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
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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.
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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
High plasticity clays
0.0 – 2.0 0.03 1
KP33.0 – 33.2 200 CPT084_BH214 to CPT084_BH217
High plasticity clays
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
High plasticity clay 0.2 – 1.5 0.06 3
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
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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
High plasticity clay 0.5 – 2.0 0.04 2
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)