marine treated wastewater discharge management plan-1

FOSTER WHEELER WORLEYPARSONS

PROJECT REPORT

MARINE TREATED WASTEWATER DISCHARGE MANAGEMENT PLAN

XA6400AH0005 PAGE 3 of 70 REV 2 DSN 54988

Y:\6.0_HSE\6.1 Environment\Environmental Management Plans (EMPs)\Marine Treated Waste Water Discharge Management Plan\Rev 2\DRIMS-#4627288-v1-Pluto_LNG_-_Draft_Marine_Treated_Wastewater_Discharge_Management_Plan_(Rev_2) (5).doc 14744-64-EN-PP-001_Rev 0

TABLE OF CONTENTS

1. INTRODUCTION 4 1.1 Purpose 4 1.2 Approval and Distribution 4 1.3 Acronyms and Abbreviations 8

2. OVERVIEW OF WASTEWATER COLLECTION, TREATMENT AND DISPOSAL 10

2.1 Re-use and Disposal Philosophy 10 2.2 Wastewater Collection, Treatment and Disposal Systems Design 11

3. MARINE TREATED WASTEWATER DISCHARGE MANAGEMENT PLAN 17

3.1 Management Plan Objectives 17 3.2 Multi-User Brine Return Line Outfall Zone - Environmental Values,

Environmental Quality Objectives, Levels of Ecological Protection 18 3.3 Discharge Regime and Flow Rate 18 3.4 Material Balance and Inventories from Effluent Treatment Plant 20 3.5 Compliance with Relevant Guidelines and Environmental Impacts 28 3.6 Water Quality Monitoring Programme 35 3.7 Implementation of the Marine Treated Wastewater Discharge Management

Plan 37

4. CONTINGENCY WASTEWATER MANAGEMENT PLAN 40 4.1 Availability and Sparing Philosophy 40 4.2 Emergency Preparedness and Response 40 4.3 Management Options for Out of Specification Effluent 41

5. DOCUMENTS 42 5.1 References 42 5.2 Figures 44 5.3 Appendices 44 Appendix A Assessment of Best Practice Technologies for Contaminant and Nutrient

Minimisation Appendix B Assessment of Pluto Toxicity Effluent and Fate (SKM 2008)


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1. INTRODUCTION

1.1 Purpose

This Marine Treated Wastewater Discharge Management Plan (MTWDMP) has been developed to ensure that disposal of treated wastewater from operation of the Pluto LNG Project (the Project) is undertaken and managed in a way that reduces the environmental impacts to as low as reasonably practical (ALARP).

The MTWDMP also incorporates the requirements of Ministerial Statement No. 747, subsequently updated to 757. Table 1 outlines the sections within the MTWDMP where each of these requirements is addressed.

1.2 Approval and Distribution

The MTWDMP will be implemented upon approval of the Western Australian Minister for the Environment.

Once approved, it will be made publicly available via Woodsides Pluto LNG Project website:

http://www.woodside.com.au/Our+Business/Projects/Pluto/Approval+Process/Environmental+Approval.htm

This MTWDMP will be reviewed prior to commencement of operations and periodically throughout the life of the Pluto Project to ensure that any improvements and/or changes in wastewater management are reflected in this Plan. Revised Plans will be provided to the DEC for approval where significant changes in wastewater management are proposed and when the Pluto Onshore LNG Processing Plant Licence, issued under Part V of the Environmental Protection Act 1986 (EP Act), is obtained (projected 2010).


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Table 1: Cross Reference of the MTWDMP with Ministerial Statement No. 757 - Section 7

Deepwater Marine Outfall Conditions under Ministerial Statement No. 757 MTWDMP Section

7-1 If a marine wastewater discharge is required by the proponent, the proponent shall construct the associated infrastructure so that wastewater is discharged into water of depth greater than 30 metres outside the Dampier Archipelago, unless otherwise determined by the CEO under Part V of the Act.

Section 2.1

(NB: Works Approval included in separate application document)

7-2 Prior to construction of the wastewater treatment plant or the marine outfall, whichever is the sooner, the proponent, in consultation with Department of Environment and Conservation, shall prepare a Marine Treated Wastewater Discharge Management Plan to the requirements of the Minister for the Environment on advice of the Environmental Protection Authority.

The objective of this Plan is to ensure that the discharge of treated wastewater is managed to achieve simultaneously the following Environmental Quality Objectives as described in the document, Pilbara Coastal Water Quality Consultation Outcomes: Environmental Values and Environmental Quality Objectives (Department of Environment, March 2006):

Maintenance of ecosystem integrity with spatially-assigned levels of protection; Maintenance of aquatic life for human consumption assigned to all parts of the marine

environment surrounding the ocean outlet;

Maintenance of primary contact recreation values assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of secondary contact recreation values assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of aesthetic values assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of cultural and spiritual values assigned to all parts of the marine environment surrounding the ocean outlet; and

Maintenance of Industrial Water Supply. This Plan shall address the following:

1. determination of the effect of wastewater flow rate on the number of dilutions the diffuser is predicted to achieve within the zone of initial dilution at maximum flow rate;

2. setting of environmental values, environmental quality objectives and levels of ecological protection to be achieved around the outfall;

3. identification of a range of feasible and practical management options and the environmental quality indicators and associated trigger levels for the implementation of remedial, management and/or preventative actions to protect the water quality and the marine environment based on the guidelines and recommended approaches in ANZECC/ARMCANZ (2000);

4. Whole Effluent Toxicity (WET) testing of wastewater, consistent with ANZECC requirements, and addressing the items in schedule 5 (attached);

5. redesign and incorporation of a new diffuser, including timelines, in the event that the WET testing results show that the original wastewater diffuser is not achieving sufficient dilutions to meet a high level of ecological protection at the edge of the mixing zone;

6. verification of diffuser performance in terms of achieving the required number of initial dilutions under low energy/calm meteorological and sea-state conditions to achieve a high level of ecosystem protection (99% species protection) at the edge of the approved mixing zone;

Section 3 and Section 4


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7. a monitoring program to permit determination of whether the water quality objectives are being met; and

8. protocols and schedules for reporting performance against the Environmental Quality Objectives using the environmental quality trigger levels.

7-3 The proponent shall implement the Marine Treated Wastewater Discharge Management Plan required by condition 7-2.

Section 1.2 and Section 3.7

7-4 The proponent shall make the Marine Treated Wastewater Discharge Management Plan required by condition 7-2 publicly available in a manner approved by the CEO.

Section 1.2 and Section 3.7

7-5 Prior to submitting a Works Approval application for the wastewater treatment plant, the proponent shall:

1. characterise in detail the physical and chemical composition and flow rates of all wastewater streams within the site and, using the toxicity of mixtures principles, predict the theoretical toxicity of the combined wastewater after treatment;

2. determine, for all contaminants and nutrients, the total annual loads of contaminants and nutrients in the wastewater discharge exiting the site; and

3. determine, for normal and worst-case conditions, the concentrations of contaminants and nutrients (for agreed averaging periods) in the wastewater discharge exiting the site.

Section 3 and Appendix B


7-6 Prior to submitting a Works Approval application for the wastewater treatment plant, the proponent shall demonstrate that the wastewater discharge will meet best practicable technology and waste minimisation principles for contaminants and nutrients.

Appendix A

7-7 Prior to submitting a Works Approval application for the wastewater treatment plant, the proponent shall design, and subsequently operate, plant and equipment on the site such that:

1. the contaminant concentrations in the wastewater effluent from the site, just prior to entry to the wastewater discharge system, meet (in order of preference):

the ANZECC/ARMCANZ (2000) 99% species protection level; or the ANZECC/ARMCANZ (2000) 99% species protection level at the edge of an

approved mixing zone;

2. the concentrations of contaminants in the wastewater effluent which can potentially bio-accumulate / bio-concentrate meet the ANZECC/ARMCANZ (2000) 80% species protection trigger levels just prior to entry into the wastewater discharge system; and

3. mass balances and inventories of toxicants can be maintained throughout the life of the plant so that their fate can be traced.

Section 3.4 and 3.5


7-8 Within three months following commissioning and stabilising of plant operations, the proponent shall conduct an analysis of effluent properties and contaminant concentrations, to an analytical limit of reporting agreed by the Department of Environment and Conservation, demonstrating that they are substantially consistent with predictions.

Section 3.6

7-9 Prior to operation, the proponent shall develop a Contingency Wastewater Management Plan which considers alternate options for wastewater disposal in the event that the Environmental Quality Objectives are not met as determined through Whole Effluent Toxicity testing, diffuser performance monitoring or environmental quality monitoring, to the requirements of the Minister for the Environment.

Section 4

7-10 In the event that the treatment plant malfunctions or goes off-line, the proponent shall include within the Contingency Wastewater Management Plan required by condition 7-9 alternative options for wastewater disposal to the timing and other requirements of the Minister for the Environment.

Section 4


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7-11 In the event that the Environmental Quality Objectives are not being met, the proponent shall implement the Contingency Wastewater Management Plan required by condition 7-9.

Section 4

7-12 The proponent shall review and revise the Contingency Wastewater Management Plan required by condition 7-9, as and when directed by the CEO.

Section 4

7-13 The proponent shall make any revisions of the Contingency Wastewater Management Plan, as required by condition 7-12, publicly available in a manner approved by the CEO.

Section 4


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1.3 Acronyms and Abbreviations ALARP As Low As Reasonably Practical

aMDEA activated Methyl Di-Ethanol Amine

ANZECC Australian and New Zealand Environment and Conservation Council

AOC Accidentally Oil Contaminated (drainage system)

ARMCANZ Agriculture and Resource Management Council of Australia and New Zealand

BAT Best Available Technology

BOD5 / BOD Biochemical Oxygen Demand (5 day)

BPM Best Practicable Measures

BTEX Benzene, Toluene, Ethyl Benzene, Xylene

CD Closed Drainage (system)

CDF Controlled Discharge Facility

CFU Colony-Forming Units

COC Continuously Oil Contaminated (drainage system)

COD Chemical Oxygen Demand

CO2 Carbon Dioxide

CPI Corrugated Plate interceptor

DCS Distributed Control System

DEC Department of Environment and Conservation

DO Dissolved Oxygen

EOF Entirely Oil-Free (drainage system)

EPA Environmental Protection Authority

EP Act Environmental Protection Act 1986

EQC Environmental Quality Criteria

EQG Environmental Quality Guideline

EQMF Environmental Quality Management Framework

EQO Environmental Quality Objective

ETP Effluent Treatment Plant

EV Environmental Value

FWW Foster Wheeler WorleyParsons

HAT Highest Astronomical Tide

LAT Lowest Astronomical Tide

LEP Level of Ecological Protection

LNG Liquefied Natural Gas

MBR Membrane BioReactor

MCC Motor Control Centre

MEG Mono Ethylene Glycol


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ML Mega litre

MPN Most-Probable-Number

MPPE Macro Porous Polymer Extraction

MUBRL Multi User Brine Return Line (part of Water Corporations infrastructure for Burrup Peninsula Desalinated Water and Seawater Supplies Project).

MTWDMP Marine Treated Wastewater Discharge Management Plan

PAC Powdered Activated Carbon

PE Population Equivalent

PSU Practical Salinity Unit

PW Produced Water

RAS Return Activated Sludge

RO Reverse Osmosis

RWP Recovered Water Plant

STP Sewage Treatment Plant

TDS Total Dissolved Salts

TOC Total Organic Carbon

TIDS Total Inorganic Dissolved Salts

TSS Total Suspended Solids

UV Ultra violet

L Micro litres

WA Western Australia

WBPL Woodside Burrup Pty Ltd

WET Whole Effluent Toxicity

WW Waste Water

WWTP Wastewater Treatment Plant


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2. OVERVIEW OF WASTEWATER COLLECTION, TREATMENT AND DISPOSAL

2.1 Re-use and Disposal Philosophy

Throughout the Pluto Project environmental assessment process, both State and Commonwealth regulators advised that wastewater discharges to Mermaid Sound should be avoided and all options for reuse to be exhausted before a discharge is contemplated (refer to Environmental Protection Authority (EPA) Bulletin 1259).

As a consequence, various water recovery studies and re-use options have been assessed by Woodside (FWW 2006, FWW 2008). The most significant outcome of these investigations included the revision of the reference case for wastewater treatment to provide for extensive treatment of all wastewater streams to meet plant service water specifications. This enables extensive reuse of treated wastewater within the Pluto LNG plant resulting in substantially reduced surplus volume requiring disposal.

However, water balance studies indicate that treated effluent will at times be in excess of on-site service water demand. Furthermore, no re-use application has been identified for the concentrate stream from the Pluto demineralised (Demin) water plant. Thus zero discharge is impractical without considering other disposal options.

Initial discussions between Woodside and third parties on the potential market for Pluto's excess treated reuse water were positive. However, any agreement with a third party to accept Pluto's treated water requires a reliable/predictable supply. In the short to medium term the Pluto facilities will utilise all of the normal produced volume of reuse water. Volumes in excess of the Pluto site requirements will only be available on an infrequent and unplanned basis, primarily associated with storm events. Therefore, given the uncertainty associated with volumes that could be made available for third party reuse, discussions with third parties have been suspended. However, as the Pluto wellfield ages, produced water quantities are expected to increase and will eventually result in reuse water quantities that consistently exceed Pluto site service water requirements. At that stage, Woodside commit to re-commence discussions with interested parties.

Thus, the option to discharge to the ocean needs to be retained to provide a disposal route for demineralised water plant concentrate and infrequent volumes of excess treated effluent. Options for ocean discharge considered (Woodside 2008) included:

1. Discharge into water of depth greater than 30 m outside the Dampier Archipelago (refer to Ministerial Condition 7-1),

2. Discharge via a purpose built diffuser located at the end of the Pluto export jetty, and


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3. Discharge into Water Corporations existing multi-user brine return line (MUBRL) with outfall located in King Bay.

Option 2 was included as the base case in the PER; however, in line with regulatory and stakeholder preference (refer to EPA Bulletin 1259), option 3 was also taken forward for detailed consideration. In summary, discharge to Water Corporations existing MUBRL has now been adopted as the preferred approach based on environmental grounds given:

the outfall and mixing zone has environmental approval (refer to Ministerial Statement 594);

ANZECC (2000) guidelines are met at the point of discharge into the MUBRL for most contaminants, and at the edge of the approved mixing zone for all contaminants;

the option utilises an existing outfall and support infrastructure; and the outfall has sufficient line capacity to receive surplus treated effluent from

the Pluto Project.

Option 1 would involve construction of a pipeline on the seabed, approximately 25 to 35 km long. This option has been eliminated from further assessment due to potential seabed and coral impacts associated with pipeline construction, capital expenditure (estimated to be in excess of $50 million) and the operational costs associated with pumping and maintenance. In addition, the ETP has been designed to maximise reuse of wastewater, as plant service water, hence, it is considered unwarranted to require Woodside to construct a 25 35 km pipeline to discharge surplus or non-routine discharges of wastewater treated to meet a high specification.

2.2 Wastewater Collection, Treatment and Disposal Systems Design

Provided in Sections 2.2.1 to 2.2.7 is a brief summary of the systems selected for the collection, treatment, re-use and disposal of wastewater streams for the Pluto Project.

A wastewater process flow diagram is provided in Figure 1. Further detail relating to the design and selection of best practice technologies is contained within Appendix A.


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Figure 1 Pluto Effluent Treatment and Reuse Process Schematic


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2.2.1 Effluent Streams, Collection and Drainage Systems

Drainage systems shall be provided to ensure the segregation and direction to appropriate treatment and/or disposal facilities of effluent from the process, utilities and contaminated surface water streams, as well as domestic effluent from the LNG Plant site. These effluent streams and collection systems are described in the following paragraphs below.

Entirely Oil-Free (EOF) - open surface water drainage system designed to collect and direct clean water from outside of kerbed areas around process facilities (Site B) and bunded areas around the storage tanks (Site A and B). There is no risk of contamination of EOF water from the Pluto LNG facilities. The EOF drainage system shall direct EOF water via a network of open channels, ditches, sumps and pipes where it can be disposed of to natural drainage lines around the site, without treatment. In the event of a spill within EOF areas, implementation of spill response procedures will ensure immediate cleanup of spills from EOF surfaces and maintain clean EOF areas.

Accidentally Oil-Contaminated (AOC) - collection of surface water run-off by means of a network of surface drain channels and liquid filled underground pipe headers, which discharge effluent under gravity to the Controlled Discharge Facility (CDF). AOC drainage areas are considered to be areas in which an oily emission is not expected to occur during normal operation, but which is at risk of accidental contamination with oil or other contaminants, i.e. accidental spills. Accidental spillages shall be contained by kerbs or floor slopes in the process areas and bunds for storage tank areas. AOC areas are designed to limit ingress of rain and prevent overflow to the surrounding paved areas. Implementing spill response procedures will also ensure immediate clean-up of spillages from AOC surfaces and maintain clean kerbed and bunded areas. Once collected in the CDF, AOC water will be tested and either forwarded for treatment if contaminated or released to the environment if not contaminated.

Continuously Oil-Contaminated (COC) - drainage system collects any oily leakages from equipment by localised kerbs, drip trays, drain trays, funnels, etc. Collected COC effluent shall be directed (via vacuum tanker or direct pumping) to the oily water equalisation tanks within the effluent treatment plant (ETP) for further processing. COC sources include equipment or packages with a high potential for lubrication oil leakage (e.g. pumps, gearbox, compressor skids and hydraulic packages) and the jetty head (condensate loading arm).

Process Closed Drainage systems (CD) includes closed process drainage systems within the acid gas removal area containing amine compounds (aMDEA), and within the mono ethylene glycol (MEG) regeneration area containing MEG. CD systems are considered part of the unit, whereby drainage is recovered into the process, and fluids are not discharged to the oily water drainage systems or ETP.


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Produced Water (PW) is primarily condensed water with a small amount of formation water. The condensed water flow is expected to be relatively consistent; however, formation water is expected to increase in volume with time as the wellfield ages. PW will be dissolved into the MEG phase in the offshore trunk line and will be carried onshore as a multiphase mixture of gas, condensate and MEG/water. Onshore, the MEG/water phase shall be separated from the hydrocarbon gas and condensate in the slug catcher and the MEG/water phase sent to the MEG regeneration system.

The aqueous vapour phase overhead from the MEG distillation process shall be condensed to produce, effectively, distilled water with some MEG and benzene, toluene, ethyl benzene and xylene (BTEX), which is pumped directly to the ETP for treatment.

2.2.2 Process Effluent Management and Treatment Systems

The process effluent management and treatment systems include:

Effluent segregation and drainage collection (as described above). Controlled Discharge Facility (CDF) - all AOC effluents from the plant areas

shall be discharged through an under ground header and/or open channels to the central CDF inlet channel. The function of the CDF is to segregate AOC drainage and direct it to the ETP; this system also caters for rain water runoff and allows for segregation, inspection and testing of water quality before a decision is taken to discharge to the EOF surface water system if not contaminated, or to the ETP for further treatment if contaminated. The basins will be constructed from reinforced concrete and incorporate a first flush compartment and a peak overflow compartment.

Effluent Treatment Plant (ETP) - for treatment of COC, contaminated AOC and produced water. The Pluto ETP provides primary, secondary and tertiary treatment of contaminated water prior to reuse or marine discharge via the MUBRL. These treatment systems are detailed further in the sections below.

2.2.3 Primary Waste Water Treatment

Oily Water Equalisation - equalisation of the COC effluents, MEG Overheads (PW) and contaminated AOC effluent shall be provided within the oily water equalisation tanks, which ensures homogeneity of influent flow and reduces contaminant load variations to provide a relatively consistent feed stream to downstream processes.

Oil Slops Tanks - collect free hydrocarbons separated from within the ETP. Free hydrocarbons shall arise from the CDF (from floating oil skimmers), oily water equalisation (from in-tank oil skimmers), oily floats from the corrugated plate interceptor (CPI) and recovered hydrocarbons from the macro porous polymer extraction (MPPE) unit. Aqueous supernatant from the oil slops tanks shall be decanted into the effluent treatment plant COC drainage system. Oil slops shall be pumped to the condensate storage tanks.


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Corrugated Plate Interceptor (CPI) - provides removal of free hydrocarbons and settleable sludges. Free hydrocarbons (oily floats) will drain to the oil slops tanks. Silty sludges shall be either transferred by vacuum tanker to the sludge digester tanks or tankered offsite for disposal at an approved facility.

Effluent Neutralisation - pH correction is provided for upstream of MPPE, with further pH correction prior to secondary treatment.

Effluent Cooling - to achieve stable operation and optimise biological treatment, the effluent temperature shall be cooled by two-stage cooling using evaporative cooling water and chilled water cooling.

Macro Porous Polymer Extraction (MPPE) - the BTEX compounds present in the condensed overhead phase from the MEG regeneration process are potentially inhibitory to bacterial growth. The MPPE unit shall reduce the BTEX contaminant levels prior to subsequent biotreatment.

2.2.4 Secondary (Biological) Waste Water Treatment

Biological treatment to degrade soluble hydrocarbons and MEG shall be provided by the use of membrane bioreactors (MBR). The MBR package is an activated sludge process which uses a semi-permeable membrane barrier system to separate the treated effluent from the organics degrading micro-organisms. The activated sludge micro-organisms degrade the soluble organics to generate CO2 and excess biomass cells.

Given there are no significant nutrient sources for the biomass identified in the feed effluent stream to the ETP, the effluent will normally be dosed with nutrients to sustain the biological treatment process, which is required to degrade soluble hydrocarbons and MEG. Optimal dosing will ensure that a minimum nutrient level is maintained to sustain biological growth within the MBR, whilst also minimising excess nutrient discharge via the MUBRL (Multi User Brine Line). Further discussions relating to nutrients are included in Section 3.51.

2.2.5 Sludge Treatment and Disposal

Sludge Digestion - excess biosludge from the industrial biological treatment MBR shall be pumped direct to the aerobic biosludge digester. Oily water sludges shall be transferred by vacuum tanker from the CPI sludge or offsite for disposal by an approved contractor. The aerobic biosludge digester has two functions; it reduces sludge mass by aerobic endogenous degradation and provides biosludge holding capacity.

Sludge Handling - the stabilised sludge shall be tankered offsite for disposal by and approved contractor.


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2.2.6 Tertiary Waste Water Treatment

The membranes contained in the MBR are ultrafiltration membranes capable of removing suspended solids and bacteria solids down to virus size (


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3. MARINE TREATED WASTEWATER DISCHARGE MANAGEMENT PLAN

3.1 Management Plan Objectives

In accordance with Ministerial Condition 7-2, the objective of this Plan is to ensure that the discharge of treated wastewater is managed to achieve the following Environmental Quality Objectives, as described in the document Pilbara Coastal Water Quality Outcomes: Environmental Values and Environmental Quality Objectives (DoE 2006):

Maintenance of ecosystem integrity with spatially-assigned levels of protection;

Maintenance of aquatic life for human consumption assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of primary contact recreation values assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of secondary contact recreation values assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of aesthetic values assigned to all parts of the marine environment surrounding the ocean outlet;

Maintenance of cultural and spiritual values assigned to all parts of the marine environment surrounding the ocean outlet; and

Maintenance of Industrial Water Supply. To achieve the above objectives, the proposed wastewater treatment and disposal operations will be managed to reduce the risk of environmental impacts to ALARP. This will be achieved through implementation of best practicable technology in wastewater treatment, whole effluent toxicity (WET) testing to determine the toxicity of the wastewater, day to day operational environmental management, a comprehensive monitoring programme and contingency measures.

An assessment of worldwide best practicable technology for wastewater treatment and the application of best practicable technology for Pluto wastewater management is included in Appendix A.


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3.2 Multi-User Brine Return Line Outfall Zone - Environmental Values, Environmental Quality Objectives, Levels of Ecological Protection

The Pilbara Coastal Water Quality Consultation Outcomes: Environmental Values and Environmental Quality Objectives was released in March 2006 (DoE 2006). This document establishes an Environmental Quality Management Framework (EQMF) and presents interim environmental goals (Environmental Values, EVs, and Environmental Quality Objectives, EQOs) and spatially allocates these goals (Levels of Ecological Protection, LEPs) for state waters of the Pilbara coast.

While there are no specific levels set for water quality parameters, the aim of the ratings of high, moderate and low LEPs are considered to be equivalent to the ANZECC (2000) guidelines for species protection, such that the high LEP is equivalent to the 99% Species Level of Protection and the moderate LEP is equivalent to the 90% Species Level of Protection, and the low LEP is equivalent to the 80% Species Level of Protection from ANZECC (2000).

The 0.01 km2 mixing zone around the MUBRL outfall has been afforded a low LEP and, at the edge of the mixing zone, a high LEP has been assigned (refer to DoE 2006, Map 9, note 4). Woodside intend to use a moderate LEP (90% Species Level of Protection) in the mixing zone as a trigger level for further investigation. Woodside intends to implement the following trigger levels:

- meeting ANZECC 90% species protection at end of pipe (contaminants)

- meeting ANZECC 80% species protection at end of pipe (bioaccumulants/ bioconcentratation)

- meeting ANZECC 99% species protection at end of mixing zone.

The discharge of wastewater through the MUBRL into King Bay is regulated through Ministerial Statement 594 as part of Water Corporations Desalinated Water and Seawater Supplies Project. As a result, Woodside has a contractual requirement with the Water Corporation to achieve specified criteria for temperature, concentration of biocide and antiscalent at the point of discharge into the MUBRL.

3.3 Discharge Regime and Flow Rate

3.3.1 Discharge from Pluto ETP to the MUBRL

The current design assumes batch discharge to the MUBRL from the final inspection tanks. The discharge will be intermittent and each batch will be tested or characterised prior to release. Any batch of effluent that does not meet discharge criteria will not be discharged to the brine line. Given that discharge will be batch discharge, instead of continuous discharge, averaging periods are not considered to be applicable.


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When discharging, the discharge flow will be 104 m3/hr and will vary in frequency depending on a number of operational parameters including:

Pluto well-field water production (i.e. during early years of operation wellfield produced water volume is low, and as the wellfield ages produced water volume increases);

Status of MEG recovery operations; Significant rainfall in past 3 days; and Service water and demineralised water demand. Note that the following assumptions have been made:

Flow into final inspection tanks is of constant composition, and Shut-down events are not regular or prolonged enough to significantly raise

contaminant concentrations or volumes to the MUBRL and subsequently breach guidelines.

Summarised below in Table 2 are operating scenarios that typify the minimum, maximum and average discharge scenarios over the life of the Pluto Project.

Table 2 Operating Discharge Scenarios

Scenario 1 - Min PW flow and dry weather 2 - Min PW flow and wet weather

3 - High PW flow and dry weather

4 - High PW flow and wet weather

Scenario Description

All treated effluent recovered & reused as service water and demin feed.

Only a portion of treated effluent reused as service water, i.e. excess to requirements.

Slight excess of treated effluent produced beyond service water requirements.

Only a portion of treated effluent reused as service water, i.e. excess to requirements.

Effluent Stream(s) discharged to MUBRL

RO concentrate and brine wastes from demin plant.

Excess treated effluent, RO concentrate and brine wastes from demin plant.



Discharge Volume

Average 40 m3 per day (intermittent discharge).




TDS of discharged effluent

2,000 - 10,000 mg/L < 1,000 mg/L < 2,000 mg/L < 1,000 mg/L


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It is estimated that approximately 30,000 kL of treated effluent will be discharged to the MUBRL annually. This equates to approximately 0.04% of the total capacity discharge rate from the MUBRL (based on approved maximum discharge of 208,000 kL per day).

3.3.2 Discharge from MUBRL into King Bay

The Water Corporation has provided the following information with regard to its MUBRL and ocean outfall infrastructure (pers comm. S. Wilke, CEE 2003):

1. Outfall infrastructure consists of one brine break tank (2 ML capacity) located adjacent to Mermaid Marine, with valve opening for batch discharge once the tank is full.

2. Infrastructure discharge design capacity is 208 ML/day and is estimated to be currently operating at one third capacity with Burrup Ammonia Plant being the only other current user of the infrastructure.

3. Hydrodynamic and dispersion modelling has been undertaken to evaluate the diffuser design, effects of flow rate, and also assess impacts of tidal and wind conditions on effluent dispersion.

4. The MUBRL outfall and diffuser extends approximately 800 m from the end of the Mermaid Marine groyne. The diffuser consists of 28 nozzles at 10 m spacing (total length 280 m), with a discharge angle of 30 above horizontal. To maximise mixing of the discharge with ambient seawater, the diffuser ports are directed alternately into and away from the dominant current, and discharge occurs at a fixed exit velocity of 4.5 m/s.

5. The approved mixing zone area is 0.01 km2 and dispersion modelling indicates that the diffuser arrangement achieves a 19:1 dilution at the edge of this mixing zone. This dilution rate has been verified by Water Corporation.

3.4 Material Balance and Inventories from Effluent Treatment Plant

Figure 2 below shows all inputs, outputs and toxicants from the proposed Pluto effluent treatment facilities.


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Figure 2 Pluto Effluent Treatment facilities inputs and outputs

The inputs and outputs shown in Figure 2 have been assessed to determine:

the type and concentration of contaminants present; the required treatment technology for removal (refer to Appendix A for

additional information); and

the resulting contaminant levels in the various ETP output streams. Table 3 shows the outcome of this assessment for each of the main classes of contaminants. This assessment assists in determination of fate for all contaminants.

Inputs to the ETP are high in hydrocarbons (free and dissolved), primarily from the MEG Overhead and the COC. However, following treatment, all toxicants in discharge streams are reduced to trace concentrations.


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Table 3 Contaminants entering Pluto Effluent Treatment Plant Sources, Treatment & Outputs

AOC COCCondensed

MEG Overhead

Demin Water Plant

Wastes

ETP Process Chemicals

Domestic Sewage

Oil Skimming CPI

Vent Filters MPPE MBR

Emergency Adsorption

Reuse Water

Effluent to MUBRL

ETP Sludges /

Cake

Oily Slops

Spent Activated Carbon

Clean Surface Water

Discharge

Atmospheric Emissions

Treated Domestic

Wastewater

Sewage Sludge

BTEX T T H Nil Nil Nil 9 9 9 9 T T T H H Nil T* Nil NilMEG T Nil T T Nil Nil 9 T T T T Nil Nil Nil Nil NilLube Oils T T Nil Nil Nil Nil 9 9 9 9 9 N N T H Nil Nil Nil Nil NilOther Free Hydrocarbons T H Nil Nil Nil T 9 9 9 9 9 T T T H T Nil Nil Nil NilOther Dissolved Hydrocarbons T H T T Nil T 9 9 9 9 T T T H H Nil T* T TMetals T T T T T T 9 9 T T T T T T1 Nil T TAntiscalants T Nil T T T Nil 9 9 T T T T Nil Nil Nil Nil NilCorrosion Inhibitors T Nil T Nil T Nil 9 9 T T T T Nil Nil Nil Nil NilOther Production Chemicals T Nil Nil Nil Nil Nil 9 9 9 T T T T Nil Nil Nil Nil NilNutrients T T Nil T H H 9 T T T T Nil T1 Nil T T

T

H*91

Atmospheric emissions of hydrocarbons are practically minimised by use of activated carbon vent filters.Treatment process is effective for removal / reduction of this contaminant.Naturally occuring background concentrations of this contaminant are unnaffected by Pluto facility.

ETP

Inpu

t Tox

ican

ts

ETP Inputs Treatment ETP Outputs

Trace levels of Toxicant may or will be present in the corresponding ETP output. For streams discharge to the environment, discharge concentration will be below Ministerial requirements.High Concentration of Toxicant will be present in the corresponding ETP output

Flows and contaminant concentrations for all the above streams shall be monitored and recorded for the life of the facility enabling the mass balance and fate of all contaminants to be determined.

The other streams directed to the MUBRL are the combined RO concentrate and ion exchange waste stream. The RO concentrate contains concentrated salts from service water, antiscalent and possibly biocide residues.

The predicted average effluent concentrations and annual loading of the chemical constituents are listed in Table 4 (Table 1 in Appendix B). This data is based on currently available information from vendors and the Water Corporation. The data represent a conservative approach, by using a set of assumptions, in estimating the effluent inputs and quality.

The following assumptions have been made in predicting contaminant concentrations at the edge of the approved mixing zone:

1. All constituent concentrations refer to the Pluto ETP wastewater stream concentrations prior to entry to the MUBRL and at end of pipe as being the same value: that is, no cross-subsidy, interaction or dilution effects from non-Pluto discharges (within the MUBRL) are considered.

2. Assessment is based on Pluto discharge as a stand alone discharge to the MUBRL; hence, dilution with other effluents in the MUBRL has not been taken into account.

3. The effects of weathering processes and biodegradation in the mixing zone are not accounted for.


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4. Hydrodynamic and dispersion modelling undertaken by the Water Corporation indicates that the diffuser arrangement achieves at least a 19:1 dilution at the edge of the 0.01km2 mixing zone. This dilution rate has been verified in the field by the Water Corporation. Given the relatively small effluent volume contribution from Pluto, the resulting change in MUBRL effluent density, and thus buoyancy, is insignificant. As such, the dispersion modelling undertaken by Water Corporation remains valid and a 19:1 dilution is applied to Pluto treated effluent concentrations.

5. Constituent concentrations have also been predicted at the edge of the mixing zone following dilution with seawater, and taking into account respective background seawater concentrations.

Assumptions 1 and 2, in particular, show the conservatism used in estimating the effluent outputs and quality. If these assumptions are not valid, the effluent will be further diluted before reaching the end of pipe and being discharged; hence, the concentration at the entry to the MUBRL is reduced further, as is the concentration at the edge of the mixing zone. Assumption 3 is important also as, over time, weathering processes and biodegradation will reduce concentrations.

Production chemicals expected in the treated wastewater are also included in Table 4 including those production chemicals that may be used in the wastewater treatment process (for example to balance pH or enhance flocculation) but will not be discharged. That is, they will be re-circulated and/or consumed in the treatment process.

Table 4 provides for all constituents comparisons against appropriate water quality guidelines (at end of pipe and at edge of mixing zone) and/or predicted no-effect concentrations based on ecotoxicity information.

Table 4 also includes the maximum expected produced wastewater concentrations from the ETP. As stated in Section 3.3.1, wastewater will not be discharged if it is above the 90% species protection threshold specification; hence, contingencies will be implemented (Refer to Section 4) to ensure discharge meets the required threshold levels.

The theoretical maximum concentrations have also been calculated at the edge of the mixing zone. It can be seen in Table 4 that if maximum concentrations were continually discharged to the marine environment, the 99% species protection at the edge of the mixing zone would still be met for all constituents.


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Table 4 Expected Constituents, Concentrations and Loadings in Pluto Treated Wastewater Stream Assessment Against Guidelines and Toxicity Criteria

Constituent Primary Source(s) Main Control/

Removal/ Treatment Processes

Units

Average (Maximum

produced ETP) Concentration at Entry to BRL (and at end of

pipe)

ANZECC/ ARMCANZ

90% Species Protection Levels (end

of pipe)

Background Concentration

Dampier Archipelago (NWSJEMS

2006)

Average (theoretical Maximum)

Concentration at Edge of Mixing

Zone (19 dilutions + background

concentration)

ANZECC/ ARMCANZ 99%

Species Protection Levels

(at edge of mixing zone)

Loading (kg/yr)

Hydrocarbons (HCs)

Total free HCs

HC Spills within AOC (Accidental Oil

Contaminated) & COC (Continuously Oil Contaminated) catchment areas

Containment, oil retention baffles, oil skimming, Corrugate

plate interceptors (CPI), Moving Bed

Bioreactor (MPPE) & Membrane Bioreactor

(MBR).

g/L 194 (1000) ID Negligible 10 (50) ID1 5.8

g/L 238 (1000) ID Negligible 13 (50) ID1 7.1

g/L 11 (50) 900 Negligible 0.56 (2.5) 500 0.32

Total dissolved HCs, incl.

BTEX

Benzene

Total PAHs1 g/L 19 (100) 90 Negligible 0.95 (5) 511 0.58

Phenol

Condensed MEG Overhead from U-2100 & HC spills

within AOC & COC catchment areas.

MPPE & MBR

g/L 195 (1000) 520 Negligible 10 (50) 270 5.8 Metals

Total Chromium2

Water Corporation Potable Water

supply, pipeline corrosion products & produced formation

waters.

g/L 0.38 (1.5) 48.6 0.18 0.19 (0.25) 7.72 0.01

Chromium (VI)2

Pipeline corrosion products &

Expected to be below limits. Some minimal adsorption / removal

in physical & biological treatment

processes. Emergency

adsorption available g/L 0.02 (0.06) 20 ND 0.001 (0.003) 0.14 0.001


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Units

Average (Maximum


pipe)

ANZECC/ ARMCANZ


of pipe)



2006)




concentration)

ANZECC/ ARMCANZ 99%



Loading (kg/yr)

production chemicals

Lead

Water Corporation Potable Water supply

& produced formation waters.

g/L 0.5 (1.5) 6.6 0.01 0.03 (0.08) 2.2 0.015

Nickel g/L 0.84 (3.3) 200 ND 0.04 (0.17) 7 0.03

Zinc

Water Corporation Potable Water

supply, pipeline corrosion products & produced formation

waters.

g/L 6.87 (36) 23 0.14 0.48 (1.93) 7 0.21

Cadmium g/L 0.10 (1.5) 14 0.005 0.01 (0.08) 0.7 0.003 Copper g/L 0.92 (3.6) 3 0.12 0.16 (0.29) 0.3 0.027

Mercury3 g/L 0.01 (0.03) 1.43 0.0004 0.001 (0.002) - 0.0003 Silver

Produced formation water

if required.

g/L 1.1 (3) 1.8 ND 0.06 (0.15) 0.8 0.03 Others

Temperature

Condensed MEG overhead, ambient conditions & solar

radiation.

Evaporative cooling & refrigerative

cooling. 0C Compliant4 - ND Compliant4 - Not Applicable

pH

Acids & bases used for water treatment processes (demin

plant & effluent treatment plant).

Acid base neutralisation.

pH units 7.4 (6.0-9.0) 8.0 - 8.4 ND 8.1 (7.3-8.2) 8.0 - 8.4

Not Applicable


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Units

Average (Maximum


pipe)

ANZECC/ ARMCANZ


of pipe)



2006)




concentration)

ANZECC/ ARMCANZ 99%



Loading (kg/yr)

Sulphide No significant sources.

No treatment required but any present would be

stripped / oxidised within MBR.

g/L 5 (10) ID ND 0.26 (0.5) 1 0.15

Process Additives

MEG

Unit 2100 MEG regeneration

distillation column condensed overheads.

Production chemical spillage.

Containment, MBR g/L 4,225 (15,000) ID ND (assumed

to be negligible)

222 (750) 50,000 127

aMDEA Production chemical spillage / leaks / loss

of containment.

Containment, MPPE & MBR g/L 185 (1,000) ID

ND (assumed to be

negligible) 9.25 (50) 2005 5.6

Liquid Polyelectrolyte

Sodium Hypochlorite

Utilised in batch cleaning of MBR membranes with no residual chlorine expected in discharge.

Citric Acid Utilised in batch cleaning of MBR membranes with no residual expected in discharge. Sodium

Hydroxide Utilised for pH dosing with no residual expected in

discharge.

Biocide Very low volumes used in closed loop cooling water systems - not discharged. Calcium

Hydroxide Utilised in sludge press as a filtration aid not

discharged

Not expected in discharge


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Units

Average (Maximum


pipe)

ANZECC/ ARMCANZ


of pipe)



2006)




concentration)

ANZECC/ ARMCANZ 99%



Loading (kg/yr)

Nutrients

Total Phosphorus

Phosphoric acid (phosphorus source

for MBR)

Consumed during MBR processes g/L 1350 (10,000) Annual load

6 ND Not applicable 157 41

Total Nitrogen Urea solution

(nitrogen source for MBR)

g/L 4125 (25,000) Annual load6 ND Not applicable 1008 124

Ammonia Nitrogen (as

N)

Urea solution (nitrogen source for

MBR) g/L 325 (1,000) 1200 ND Not applicable 500 10

ND = Background data not available (background concentrations were assumed to be zero for the purpose of calculation of edge of mixing zone concentration) ID = Insufficient Data (ANZECC/ARMCANZ 2000) 1. 99% Species protection level guideline for Naphthalene (ANZECC/ARMCANZ 2000) 2. 99% Species protection level guideline for CR III (ANZECC/ARMCANZ 2000). Chromium VI is the highly toxic form of Chromium, so when total Cr is given it is usually

compared to ANZECC/ARMCANZ criteria for Cr III. If and when Cr VI is measured, then it is compared directly to the Cr VI criteria 3. ANZECC/ARMCANZ 80% Species Protection Level applied to end of pipe concentration is applicable as mercury has the potential to bioaccumulate 4. Water Corp criteria for temperature - temperature differential at Pluto/BRL tie in point < 2 degrees C for 80% of the time and never exceeds 5 degrees C. NB:

Temperature differential measured between Water Corporation inlet pipe (measured by Water Corp) and Pluto tie in point to BRL - TBC. 5. Lowest EC 50 for aMDEA (from Table A1 in Appendix B) with application factor (safety factor) of 100 applied 6. Assessment of annual load on receiving environment (refer to Section 3.5.2) 7. Tropical Australia Marine Nearshore Trigger for TP (ANZECC/ARMCANZ 2000) 8. Tropical Australia Marine Nearshore Trigger for TN (ANZECC/ARMCANZ 2000)


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3.5 Compliance with Relevant Guidelines and Environmental Impacts

As per Section 3.2, the 0.01 km2 mixing zone around the MUBRL outfall has been afforded a low LEP (80% species protection) and, hence, it is considered that a trigger level equivalent to a moderate LEP (90% species protection) is appropriate for risk assessment of discharges from the Pluto ETP to the MUBRL.

However, in accordance with Ministerial Statement 757, Condition 7-7:

1. the contaminant concentrations in the wastewater effluent from the site, just prior to entry to the wastewater discharge system, meet (in order of preference):

the ANZECC/ARMCANZ (2000) 99% species protection level; or the ANZECC/ARMCANZ (2000) 99% species protection level at the edge

of an approved mixing zone;

2. the concentrations of contaminants in the wastewater effluent which can potentially bio-accumulate/bio-concentrate meet the ANZECC/ARMCANZ (2000) 80% species protection trigger levels just prior to entry into the wastewater discharge system;

Hence, presented in Table 4 are the predicted contaminant concentrations for discharge to the MUBRL compared against both the 99% species protection trigger levels (at entry to the mixing zone), as well as 99% species protection species protection level at the edge of 0.01 km2 mixing zone.

Predicted concentrations shown in Table 4 indicate that:

1. Average hydrocarbon concentrations meet ANZECC guideline for 99% species protection at point of discharge to the MUBRL.

2. Average heavy metals meet 90% species protection at point of discharge to the MUBRL and meet 99% species protection at the edge of the mixing zone.

3. Contaminants with the potential to bioaccumulate, i.e. mercury, meet 80% species protection at point of discharge to MUBRL.

4. Sulphide meets 99% species protection at the edge of the mixing zone.

5. Average concentrations for the process additives, MEA and aMDEA, meet 99% species protection at the entry to the MURBL.

6. Total load of nutrient discharge to the environment is low and is not expected to promote algal growth (see Section 3.5.2).

Hence, Plutos contaminant concentrations meets condition 7-7 of Plutos Ministerial Conditions.


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3.5.1 Environmental Fate and Predicted Toxicity of Pluto Effluent

The Assessment of Pluto Treated Effluent Toxicity and Fate report by SKM (2008) outlines the assessment of environmental impact associated with discharging Pluto effluent to the Mermaid Sound (Appendix B). A weight of evidence approach has been undertaken to assess the likely effects of the proposed discharge on the marine environment.

Following discharge, the wastewater effluent is subject to further processes such as dilution, evaporation, adsorption, biodegradation and photodegradation in the marine environment. An outline of the likely environmental fate of the different contaminant types are outlined below:

1. Dissolved hydrocarbons will further volatilise and evaporate if at surface and in contact with the atmosphere. Dissolved hydrocarbons do no adsorb strongly to suspended particles and are unlikely to be transported via seabed.

2. Dispersed oil, removed through adsorption to particles, followed by sedimentation and biodegradation. It is predicted that dispersed oils will biodegrade quickly in environment.

3. Poly Aromatic Hydrocarbon (PAH) concentrations are low, and considered unlikely to bioaccumulate. The levels are sufficiently low to allow rapid dilution.

4. Given the low concentrations of metals discharged and the widespread nature of the plume, which will further dilute metal concentrations to well below chronic toxic thresholds, it is unlikely that precipitates will form in quantities that may have an impact on sediment quality.

5. Process chemicals (aMDEA and MEG), which are present in the discharge stream, will be discharged at concentrations below predicted no-effect concentrations. Both these chemicals are miscible in water and readily biodegradable.

A theoretical assessment of toxicity was calculated based on available guidelines and toxicity of mixtures principles. The assessment identified that for all chemical classes, the predicted toxicity is


PROJECT REPORT




relatively low in both species richness and abundance. As the MUBRL has been in operation since 2006, the marine environment in the vicinity of the MUBRL is not pristine. Discharge of Pluto effluent via the MURBL is unlikely to significantly impact upon the marine environment or King Bay.

3.5.2 Nutrient Loadings

Whilst the ANZECC water quality guidelines may be used to assess the environmental significance of some wastewater contaminant concentrations entering King Bay, load-based guidelines for nutrients are considered more appropriate than a discharge concentration. This is because environmental impacts arise from secondary effects, such as excessive algal growth due to elevated nutrient concentrations; biomass is controlled primarily by the total mass of these nutrients available to the growing algae rather than the concentration of the nutrients.

Annual discharges of 41 kg and 124 kg for Total Phosphorous and Total Nitrogen, respectively, are not expected to influence algal growth. The treated effluent will be discharged into King Bay upon which it will rapidly disperse into Mermaid Sound as a result of a combination of strong tidal currents and wind driven circulation. It is therefore unlikely that a build-up of nutrient concentrations will occur.

As a comparison, nitrogen loadings from Bunbury and Perth metropolitan wastewater treatment plants are in the order of many tonnes per annum. Impacts on the marine environment of King Bay due to nutrient loadings provided in Table 4 are not expected.

3.5.3 Compliance with Social Environmental Values

Table 5 includes an assessment of compliance with ecological (based on Table 4 concentrations at edge of mixing zone) and social values that are based on discharging into an area with a Low LEP (mixing zone) surrounded by an area of High LEP (King Bay) (SKM 2008).


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Table 5 Assessment of Compliance with Social Values

Environmental Value (EV)

Environmental Quality Objective

(EQO)

Environmental Quality Criteria (EQC)

Environmental Quality Guideline (EQG) / Environmental Quality Criteria (EQC)

Assessment of Treated Waste Water Discharge

Ecosystem Health

Maintenance of ecosystem Integrity

Refer to Table 4 Refer to Table 4 As per Table 4 all EQGs fall within guidelines at edge of mixing zone.

WET testing will determine the toxicity of the wastewater and evaluate the potential risks to the marine environment associated with marine discharge.

Fishing and Aquaculture

Seafood for Human Consumption

Thermotolerant faecal coliforms in water.

Thermotolerant faecal coliforms in fish flesh.

Metals and organics in fish flesh.

EQG: The median thermotolerant faecal coliform bacterial concentration should not exceed 14 CFU/100 mL, with no more than 10% of the samples exceeding 21 CFU/100 mL measured using the membrane filtration method.

EQS: Fish destined for human consumption should not exceed a limit of 2.3 MPN E. coli /g of flesh (wet wt.) in four out of five representative samples, and the fifth sample should not exceed 7 MPN E. coli /g, with a maximum total plate count of 250 000 organisms/g.

EQG: A range of metals and organics have environmental quality guidelines for levels in fish flesh.

Treated effluent from the domestic STP will be discharged via land application and will not be discharged to the MUBRL.

Hence, the median thermotolerant faecal coliform bacterial concentration is not expected to exceed EQGs.


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(EQO)




Fishing and Aquaculture

Aquaculture Metals, inorganics and pesticides in water

Dissolved oxygen pH

EQG for toxicants: The 95th percentile of the sample concentrations from the area of concern (either from one sampling run or all samples over an agreed period of time, or from a single site over an agreed period of time) should not exceed the environmental quality guideline value.

EQG for physio-chemical stressors: The median of the sample concentrations from the area of concern (either from one sampling run or all samples over an agreed period of time, or from a single site over an agreed period of time) should not exceed the following environmental quality guideline values.

- Dissolved Oxygen 5 mg/L - pH 6-9

EQGs for potential toxicants of concern for a high protection of the marine ecosystem are more stringent than those for aquaculture values (with the exception of zinc) and will therefore be protected through adherence to the ecosystem EQGs.

There are presently no active aquaculture leases in King Bay.

pH and DO levels at end of pipe are highly unlikely to vary significantly outside of the EQG.

Recreation and aesthetics

Primary contact recreation values

Faecal Pathogens pH Water clarity Toxic Chemicals a range

of chemicals including metals, inorganics and organics.

EQG: Faecal Pathogens: The 95%ile bacterial content of marine waters should not exceed 200 enterococci/100mL

EQS: The median of the sample concentrations from the area of concern (either from one sampling run or from a single site over an agreed period of time) should not exceed the range of 5 9 pH units.

EQG: To protect the visual clarity of waters used for swimming, the horizontal sighting of a 200 mm diameter black disc should exceed 1.6 m.

EQG: Toxic Chemicals - The 95%ile of the sample concentrations from the area of concern (either


Hence, it is considered unlikely that discharged wastewater will cause faecal pathogens to exceed EQG in the vicinity of the discharge.

EQGs for potential toxicants of concern (metals) for a high protection of the marine ecosystem are more stringent than those for primary contact recreation values (except for Benzene see below) and will therefore be protected through adherence to the ecosystem EQGs.

pH levels at end of pipe are highly unlikely to vary


PROJECT REPORT







(EQO)




from one sampling run or from a single site over an agreed period of time) should not exceed the environmental quality guideline values.

significantly outside of the EQS.

Primary contact recreation EQGs for metals will be met immediately after discharge. Expected concentrations for benzene will be well below the primary recreation EQG (0.02 mg/L), within metres of the discharge under worse conditions.


Secondary contact recreation values

Faecal pathogens pH Toxic chemicals

EQG: The 95%ile bacterial content of marine waters should not exceed 2000 enterococci/100mL.

The median of the sample concentrations from the area of concern (either from one sampling run or from a single site over an agreed period of time) should not exceed the range of 5 9 pH units.

Water should contain no chemicals at concentrations that can irritate the skin of the human body.


Hence, it is considered unlikely that discharged wastewater will cause faecal pathogens to exceed 2000 enterococci/100mL in the vicinity of the discharge.

pH levels at end of pipe are highly unlikely to vary significantly outside of the EQS.

Given the high level of treatment proposed, it is highly unlikely that treated waste water will contain chemicals at concentrations that can irritate the skin of the human body.


Aesthetic Values Water Clarity Fish Tainting Substances

(large range of chemicals implicated in fish tainting; related to concentration in water column).

The natural visual clarity of the water should not be reduced by more than 20%.

The 95%ile of the sample concentrations from the area of concern (either from one sampling run or all samples over an agreed period of time or from a single site over an agreed period of time) should not exceed the environmental quality guideline values.

Given the high level of treatment proposed, it is highly unlikely that treated waste water will result in impact on water clarity or fish flesh quality relevant to aesthetic values.


PROJECT REPORT







(EQO)




Cultural and Spiritual

Maintenance of cultural and spiritual values

No guidelines are relevant to the area within the vicinity of the discharge for cultural and spiritual values.

No guidelines are relevant to the area within the vicinity of the discharge for cultural and spiritual values.

No impacts are expected from the discharge of treated waste water on cultural and spiritual values.

Industrial Water Supply

Maintenance of industrial water supply values

No guidelines are relevant to the area within the vicinity of the discharge for industrial water supply values.

No guidelines are relevant to the area within the vicinity of the discharge for industrial water supply values.

No impacts are expected from the discharge of treated waste water discharge on industrial water supply values.


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3.6 Water Quality Monitoring Programme

An Operations Water Quality Monitoring Procedure (OQWMP) will be developed prior to commissioning, which will outline the procedures for Whole Effluent Toxicity (WET) testing, monitoring and sampling of ETP treated wastewater prior to discharge to the MUBRL.

Water quality monitoring conducted by Woodside and will focus on Woodside end-of-pipe monitoring, to ensure that discharge meets ANZECC guideline for moderate LEP (90% Species Level of Protection) as outlined previously in the MTWDMP.

Monitoring in the marine environment will be coordinated via the Burrup Users Group (BUG). Constituents which are currently not being measured via the wider monitoring program (BUG) will be added to the program; these are yet to be determined.

3.6.1 Ecotoxicity

WET testing will be undertaken on the untreated Pluto produced water and treated Pluto wastewater as soon as first water becomes available. In accordance with their Outlet Operational Monitoring Program (SKM 2005), the Water Corporation also undertakes annual ecotoxity testing on the co-mingled effluent being discharged to King Bay.

Objectives

The objectives of the WET testing program are:

to determine the toxicity of the wastewater; to evaluate the potential risks to the marine environment associated with the

marine discharge; and

to determine the number of dilutions of the wastewater which would be required to meet a high level of ecological protection (99% species protection level).

Guidelines

1. WET testing will be undertaken in accordance with the protocols and procedures recommended in ANZECC (2000).

2. Woodside will co-ordinate with the Water Corporation to ensure consistency with ecotoxicity testing undertaken by Water Corporation as part of the MUBRL Outlet Operational Monitoring Program (SKM 2005).

3. Following commissioning of the drainage and effluent treatment plant, worst-case wastewater composition operating conditions will be identified and


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wastewater samples for WET testing will be collected during these operating conditions.

4. WET testing will be undertaken within one month of commissioning (for worst-case wastewater composition operating conditions), and annually thereafter, or immediately following any significant change in the composition of the treated wastewater.

3.6.2 Operational ETP Wastewater Monitoring

The inspection tanks provide hold-up and testing of the treated effluent prior to discharge to the MUBRL. Additional automatic sampling for laboratory testing will be undertaken on the discharged effluent via the operation of a continuous sampler. The liquid effluent sampler will have a vacuum or pneumatic actuated type mode of operation and is capable of preparing continuous composite samples or time based discrete samples. In addition to the samplers, separate online analysers continually measure effluent flow, pH and temperature.

Provided below are indicative wastewater manual sample locations, parameters and frequencies based on current design. Sampling details may be subject to some change as engineering design progresses, and will be confirmed prior to operations:

1. First Flush Basin contains AOC effluent stream collected during period of wet wether and will be sampled prior to discharge to natural drainage lines via the Final Inspection Chamber (if clean) or discharge to the ETP (if contaminated). Sample parameters will include Total Petroleum Hydrocarbons (TPH), BTEX, BOD and physical parameters such as pH, TSS and turbidity.

2. Peak Overflow Basin - contains AOC effluent stream collected during period of heavy rain fall and will be sampled prior to discharge to natural drainage lines via the Final Inspection Chamber (if clean) or discharge to the ETP (if contaminated). Sample parameters will include Total Petroleum Hydrocarbons (TPH), BTEX, BOD and physical parameters such as pH, TSS and turbidity.

3. ETP Final Inspection Tanks T-6438A/B contains treated (i.e. excess MBR treatment) AOC, COC and produced water stream, and will be sampled prior to discharge to the MUBRL. Sample parameters will include as a minimum those listed in Table 4, as well as Total Organic Carbon (TOC), biocide and antiscalent. Online analysers will continually measure effluent flow, pH and temperature on the discharge pipe.

3.6.3 Outfall and Ocean Monitoring undertaken by Water Corporation

The Water Corporation has implemented an operational monitoring program around the outfall to monitor and report on both non-compliance and potential impacts on the marine environment by the brine and wastewater discharge (SKM 2005).


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This monitoring program includes the collection of water, sediment and biota samples from locations surrounding the outfall and mixing zone. The program also includes ecotoxicity testing of effluent discharged from the MUBRL.

In addition to the operational ocean monitoring program, continuous monitoring of flow rate, temperature, pH, conductivity, REDOX potential, ammonia and turbidity occurs at the outfall. Water Corporation also monitors concentrations of oxidising biocide and antiscalent in the effluent discharge.

3.7 Implementation of the Marine Treated Wastewater Discharge Management Plan

This MTWDMP will form the basis of the environmental management strategy for the disposal of treated wastewater from operation of the Project and is supported by monitoring programs detailed in Section 3.6.

As outlined in Section 1.2, the MTWDMP will be reviewed and updated prior to commencement of operations, and will then be implemented upon approval from the Western Australian Minister for the Environment. The MTWDMP will also be reviewed periodically throughout the life of the Pluto Project to ensure that any improvements and/or changes in wastewater management are reflected in this Plan. Revised Plans will be provided to the DEC for approval where significant changes in wastewater management are proposed.

3.7.1 Roles and Responsibilities

Table 6 details the responsibilities in terms of environmental management of each party involved in treated wastewater disposal activities.

Table 6 Roles and Responsibilities for Implementation of the MTWDMP

Role Responsibility

Woodside Operations Project Manager

Reports to Senior Management. Overall responsibility for operations activities. Review of environmental KPIs. Responsible to ensure the implementation of this MTWDMP to

project team.

Woodside ETP Operation Personnel

Reports to the Woodside Operations Project Manager. Maintains the monitoring equipment and pre-maintenance

program, to ensure that equipment operates within design specification and complies with discharge requirements and Water Corporation requirements.

Responsible for reporting environmental performance, incidents and exceedances to the Woodside Environmental Coordinator.

Woodside Environmental Coordinator

Liaison with technical team leaders on environmental issues. Day to day responsibility for communicating the requirements of

this MTWDMP to project team.


PROJECT REPORT




Table 6 Roles and Responsibilities for Implementation of the MTWDMP

Role Responsibility

Communicates license conditions. Implementation of environmental reporting, auditing and action

tracking.

Provides training on legal requirements and understanding regulated limits and consequences of exceedances.

Woodside Laboratory Personnel

Undertake regular monitoring and sampling as required. Calibration of samplers as and when required. Report / raise compliance notices.

Water Corporation

Manages the MUBRL and common outfall infrastructure as part of Water Corporations Desalinated Water and Seawater Supplies Project.

Implements the Burrup Industrial Water Supply System Outlet Operational Monitoring Program (SKM 2005).

Monitors and reports on both non-compliance and potential impacts on the marine environment, resulting from brine and wastewater discharge from the MUBRL into King Bay.

Imposes contractual obligations on system users with respect to the flow and composition of their discharge into the MUBRL.

Independently samples and analyses the individual discharges into the MUBRL on a regular basis to validate the accuracy of the data provided by system users.

Burrup User Group (BUG)

Comprises Water Corporation, DEC and s

marine treated wastewater discharge management plan-1

Documents

disposal of treated

management plan objectives

management options

pluto project

discharge regime

pluto onsho

environmental impacts

disposal philosophy