BLACKTIP PROJECT PRODUCED WATER MANAGEMENT … · UKOOA United Kingdom Offshore ... 2004a. Blacktip...

Eni Australia B.V. Level 3, 40 Kings Park Road,

West Perth WA 6005

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BLACKTIP PROJECT

PRODUCED WATER MANAGEMENT PLAN

000036_DV_EX.HSE.0381.000_A03

BLACKTIP PROJECT Produced Water Management Plan

000036_DV_EX.HSE.0381.000_A03 24 November 2010


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TABLE OF CONTENTS

ACRONYMS ............................................................................................................................6

AMENDMENT LOG .................................................................................................................8

REFERENCE DOCUMENTS ...................................................................................................9

1. INTRODUCTION...........................................................................................................10 1.1 Purpose.........................................................................................................................10 1.2 Project Description........................................................................................................10 1.3 Proponent .....................................................................................................................11 1.4 HSE Policy and Commitment........................................................................................12 1.5 Milestones.....................................................................................................................13 1.6 Legislation and Guidelines............................................................................................13

2. PRODUCED WATER TREATMENT SYSTEM ............................................................14 2.1 Produced Water Flow Rates .........................................................................................14 2.2 Treatment System.........................................................................................................14 2.3 Start Up.........................................................................................................................17 2.4 “Off-Spec” Water ...........................................................................................................17

3. ENVIRONMENTAL RISK ASSESSMENT ...................................................................18 3.1 Composition of Blacktip PW..........................................................................................18 3.2 Assessing Environmental Effects and Risks.................................................................20

3.2.1 General ............................................................................................................20 3.2.2 Toxicity .............................................................................................................20 3.2.3 Tainting ............................................................................................................25 3.2.4 Risk Assessment .............................................................................................25

3.3 Environmental Impact ...................................................................................................25 3.3.1 Marine habitats .............................................................................................................25 3.3.2 Dispersion modelling ....................................................................................................31 3.3.3 Impact on biological communities.................................................................................32

3.4 Summary.......................................................................................................................39

4. PRODUCED WATER STUDIES...................................................................................40 4.1 Overview .......................................................................................................................40 4.2 Chemical characterisation.............................................................................................40 4.3 Whole Effluent Toxicity Testing.....................................................................................40 4.4 Biodegradation..............................................................................................................41 4.5 Bioaccumulation............................................................................................................41 4.6 Marine monitoring .........................................................................................................41

5. TRIGGER FOR CORRECTIVE ACTION AND CONTINGENY ....................................43

6. INDUSTRY BEST PRACTICE......................................................................................45 6.1 Comparison with other gas plants.................................................................................45 6.2 Blacktip .........................................................................................................................46

APPENDICES........................................................................................................................47 Appendix A1: Eni HSE Policy Appendix A2: Seabed charactersitics along the pipeline route Appendix A3: Environmental Protection Licence




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TABLES

Table 1.1: Schedule of Milestones .....................................................................................13 Table 3.1: Summary of the acute, sublethal and chronic toxicity of PW from throughout

the world to different taxa of marine and freshwater organisms (Reference

[11]) ...................................................................................................................22 Table 3.2: Summary of ecotoxicological tests undertaken of PW samples collected from

Woodside facilities on the NWS (Reference [2]) ...............................................23 Table 3.3 Environmental Risk Summary – Produced Water .............................................39 Table 4.1: Target analytes for chemical characterisation and their method of

measurement.....................................................................................................40

FIGURES

Figure 1.1: Development location........................................................................................11 Figure 1.2: Blacktip onshore infrastructure ..........................................................................12 Figure 2.1: Produced water production rates.......................................................................14 Figure 2.2: Schematic of Produced Water Treatment System ............................................16 Figure 2.3: Produced water discharge location ...................................................................16 Figure 2.4: Illustration of four port discharge diffuser ..........................................................17 Figure 3.1: Ecotoxicology results for Woodside’s North West Shelf and Timor Sea

Assets (from Reference [2])...............................................................................24 Figure 3.2: Comparison of Microtox® test results between facilities (from Reference [2]) ..24 Figure 3.3: Example of seabed sediment inshore of the PW discharge ..............................27 Figure 3.4: Example of seabed sediment offshore of the PW discharge.............................28 Figure 3.5: Example of seabed sediment offshore of the PW discharge.............................29 Figure 3.6 Example of seabed sediment offshore of the PW discharge ...............................30 Figure 3.7: Predicted PW concentrations during a neap and light onshore winds for

water production of 200bwpd ............................................................................34 Figure 3.8: Time series of predicted PW concentrations at 50m from the discharge

location for water production of 200bwpd (neap tides and light onshore

winds) ................................................................................................................35 Figure 3.9: Time series of predicted PW concentrations at various beach locations for

water production of 200bwpd (neap tides and light onshore winds)..................35 Figure 3.10: Predicted PW concentrations during neap tide and light onshore winds for

water production of 6000bwpd ..........................................................................36 Figure 3.11: Time series of predicted PW concentrations at 50m from the discharge

location for water production of 6000bwpd........................................................37 Figure 3.12: Time series of predicted PW concentrations at various beach locations for

water production of 6000bwpd ..........................................................................37




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Figure 3.13: Exposure times to the PW plume for passive and motile organisms.................38 Figure 4.1: Proposed monitoring locations ..........................................................................42




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ACRONYMS

ANZECC Australian and New Zealand Environment and Conservation Council

ARMCANZ Agriculture and Resource Management Council of Australia and New Zealand

BWPD Barrels of Water Per Day

BAF Bioaccumulation Factor

BCF Bio-concentration Factor

BTEX Benzene, Toluene, Ethyl benzene and Xylene

BF Biomagnification Factor

BOD Biochemical Oxygen Demand

CALM Catenary Anchor Leg Mooring

C0 Discharge Concentration

CHARM Chemical Hazard Assessment and Risk Management

CI Corrosion Inhibitor

DEWHA Department of Environment, Water, Heritage and the Arts

DREAM Dose related Risk and Effect Assessment Model

EC50 The Median Effect Concentration

EIF Environmental Impact Factor

EIS Environmental Impact Statement

EPA Environmental Protection Agency

EPBC Environmental Protection and Biodiversity Conservation Act 1999

EPL Environmental Protection Licence

EQC Environmental Quality Criteria

HAT Highest Astronomical Tide

HDPE High Density Polyethylene

HQ Hazard Quotient

IC50 Median Inhibition Concentration

IGFU Induced Gas Flotation Unit

IR Infra-Red

Koc Organic carbon/water partition coefficient

Kow Octanol/water partition coefficient

KPI Key Performance Indicators

LAT Lowest Astronomic Tide

LC50 Median Lethal Concentration




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LTS Low Temperature Separator

MAH Monocyclic Aromatic Hydrocarbon

MLWN Mean Low Water Neap

MSDS Materials Safety Data Sheet

NE Northern Endeavour

NOEC No Observed-Effect Concentration

NORM Naturally Occurring Radioactive Material

NPD Naphthalene, Phenanthrene and Dibenzothiophene

NRETAS Natural Resources, Environment, the Arts and Sport

NT Northern Territory

NWS North West Shelf

OIW Oil In Water

OGP Onshore Gas Plant

OSPAR Oslo and Paris Commission

PAH Polycyclic Aromatic Hydrocarbons

PEC Predicted Environmental Concentration

PSU Practical Salinity Unit

PID Photoionisation detection

PNEC Predicted No Effect Concentration

PPMV Parts Per Million by Volume

P(SL)A Petroleum (Submerged Lands) Act

P(SL)(ME)R Petroleum (Submerged Lands)(Management of the Environment) Regulations

PW Produced Water

PWFD Produced Water Flash Drum

TO Traditional Owner

TOC Total Organic Carbon

UKOOA United Kingdom Offshore Operators Association

USEPA United States Environmental Pollution Authority

Woodside Woodside Energy Ltd

WET Whole Effluent Toxicity

WW Waste Water

°C Degree Celsius




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AMENDMENT LOG

Revision Page(s) Date Summary of Changes Initials A02 DEWHA and NRETAS

comment incorporated

A03 41 24/11/10 Dye dispersion Section removed as it has proved impractical to implement

40 (S4.1) Removal of reference to frequency of studies to avoid any conflict with EPL requirements.




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REFERENCE DOCUMENTS

[1] Woodside, 2004a. Blacktip Project Draft Environmental Impact Statement. Volume 1 Main Report. October 2004.

[2] Woodside 2004b. Blacktip Project Draft Environmental Impact Statement. Volume 2 Technical Appendices. October 2004.

[3] Woodside 2005. Blacktip Project. Supplement to the Environmental Impact Statement. March 2005.

[4] Office of Environment and Heritage, Northern Territory Government, 2005. Blacktip Gas Project Environmental Assessment Report And Recommendations Assessment Report No 50. October 2005.

[5] Waste Management and Pollution Control Act - http://www.nt.gov.au/nreta/environment/ legislation/management/wmpc.html

[6] ANZECC & ARMCANZ, 2000. Australian and New Zealand guidelines for fresh and marine water quality. National Water Quality Management Strategy No. 4. Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Canberra, ACT.

[7] Eni, 2007. Produced Water Treatment System. Eni document No.: 00710100DPRB00467 Rev 1.

[8] Neff, J.M, 1987. Biological effects of drilling fluids, drill cuttings and produced waters. Pages 469-538 In D.F. Boesch and N.N. Rabalais, Eds., Long term environmental effects of offshore oil and gas developments. Elsevier Applied Science Publishers, London.

[9] Johnsen, S., T.K. Frost, M. Hjelsvold and T.R. Utvik, 2000. The environmental impact factor – a proposed tool for produced water impact reduction, management and regulation. SPE Paper 61178.

[10] Cobby, G. L., 2002. Changes to the environmental management of produced formation water offshore Australia. APPEA Journal 2002.

[11] Neff, J.M., 2002. Bioaccumulation in Marine Organisms. Effects of contaminants from oil well produced water. Elsevier.

[12] OSPAR Recommendations 2000/4 on a harmonised pre-screening scheme for offshore chemicals.

[13] Johnsen, S., T.K. Frost, M. Hjelsvold and T.R. Utvik, 2000. The environmental impact factor – a proposed tool for produced water impact reduction, management and regulation. SPE Paper 61178.

[14] Fugro survey (2004). Report for the Blacktip Development Project Geophysical Surveys. Volume 2a – Survey Results Final 14 Oct 2004.

[15] Furness, R.W. and C.J. Camphuysen, 1997. Seabirds as monitors of the marine environment. ICES Journal of Marine Science, 54: 726-737.




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1. INTRODUCTION

1.1 PURPOSE

This Produced Water Management Plan (PWMP) has been prepared by Eni Australia BV (Eni) for the Blacktip Project. Its main purpose is to describe the Produced Water (PW) treatment and disposal facilities. It also provides an assessment of the likely environmental impact, presents the proposed monitoring program and contingency plans should monitoring show that the environmental impact is greater than expected.

The preparation of this management plan fulfils commitments made in the Environmental Impact Statement (EIS) (References [1], [2] and [3]) and also recommendations made by the Environmental Protection Agency (EPA) Program (formerly the Office of Environment and Heritage) in its Assessment Report to the Minister for the approval of the project (Reference [4]).

1.2 PROJECT DESCRIPTION

The Blacktip gas field is located in permit WA-279-P in the Joseph Bonaparte Gulf, approximately 110km offshore from Wadeye, Northern Territory (NT) (Figure 1.1), in about 52m of water. The field will be developed with a small unmanned offshore wellhead platform, a subsea pipeline bringing whole well stream fluid, (i.e. gas, condensate and PW) to Yelcherr Beach and an onshore gas plant (OGP) near Wadeye (Figure 1.2). The processed gas will be exported via an onshore export pipeline, by others, to the customer and the condensate will be exported via a subsea pipeline to a Catenary Anchor Leg Mooring (CALM) mooring for shipping via tanker vessel. PW will be treated and discharged through a long sea outfall.

Prior to Eni becoming the sole owner of the Blacktip development in November 2005, Eni was a participant with Woodside Energy Ltd (WEL). WEL was the nominated operator and progressed the design through the Front End Engineering Design (FEED) stage. Eni is now progressing the project through detailed design and construction.

The Blacktip development transects two principal jurisdictions, namely the offshore Commonwealth waters administered by Western Australia (WA) and NT, and onshore NT. The majority of the approvals and ongoing monitoring lie within NT jurisdiction. An EIS was prepared to fulfil the requirements of the Commonwealth Environment Protection and Biodiversity Conservation (EPBC) Act 1999 and the NT Environmental Assessment Act 1984. The EIS provides a full assessment of all potential environmental issues related to the development and presents procedures that will be put in place to ensure that environmental impacts are minimised to acceptable levels. . The Assessment Report No. 50 from the EPA Program was finalised in October 2005. Approval to develop the Blacktip Gas Field was received from the Commonwealth Government on 29th November, 2005




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1.3 PROPONENT

Eni is one of the world’s major international integrated energy companies operating large upstream projects, downstream gas and power generation infrastructure, refining and marketing activities, as well as oil field services and engineering. In Australia, Eni has a 65% stake and is Title Holder of the Woollybutt oilfield in offshore Carnarvon Basin in WA, with a 12% interest in the Bayu Undan and Darwin LNG Projects. Eni has an active exploration programme in Australia with interests in 14 permits, of which it currently operates 11.

Figure 1.1: Development location




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Figure 1.2: Blacktip onshore infrastructure

1.4 HSE POLICY AND COMMITMENT

The Blacktip project is committed to integrating the principles of effective HSE and Quality (HSEQ) management in all aspects of its activities. These include:

a conviction that high standards are achievable through proper management;

the acceptance of HSE responsibility from Eni management, exercised through a clear chain of command throughout the project organisation, including contractors;

preparing an HSEQ Plan that will facilitate implementation of the Eni HSE Policy (presented in Appendix A1), and specify key HSE activities and deliverables throughout the project phases;

applying the principles of risk management at the earliest stage of each project phase;

ensuring that all project personnel, including contractors, understand and adhere to Eni’s policies, principles and company standards;

applying relevant standards and good engineering practice, consistent with gas field developments; and

immediately rectifying areas where deficiencies have been identified or already exist, and ensuring that continual improvement is delivered through the communication and implementation of lessons learned.

Eni is committed to ensuring that all statutory HSEQ documents (eg Environmental Management Plans, Safety Cases, Pipeline Management Plans) for the construction, installation, commissioning and operation phases are prepared and submitted to

OGP

Pipeline Corridor

Access Road




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regulatory bodies in a timely manner. This process is assisted by the preparation of integrated project plans that detail HSE activities and deliverables.

The Blacktip project is also committed to ensuring that the risks to personnel and the environment at each phase of the project are evaluated (either qualitatively or quantitatively), lie within a tolerable region, and are reduced to as low as reasonably practicable (ALARP).

1.5 MILESTONES

It is intended that this PWMP is kept ‘live’, regularly reviewed and updated to reflect any changes in the facility or after any significant legal or corporate changes. The milestones listed in Table 1.1 are proposed for developing and maintaining the plan.

Table 1.1: Schedule of Milestones

Task Deadline Responsibility

Present proposed PW discharge method to

EPA

3Q 2007

(complete)

Environmental Assessment 3Q 2007

(complete)

Submit PW Management Plan to EPA, DEWR,

DPIFM and NLC

1Q 2008

Consultation with Traditional Owners (TOs) 1Q 2008

Develop detailed scopes for PW analysis and

environmental monitoring

1Q 2008

Undertake baseline marine monitoring 2Q2008

Incorporate PWMP into operations EP 2Q2008

Blacktip Environmental

Coordinator

Undertake PW Sampling and analysis Within 3

months of

commencing

production

First Post Production Marine Monitoring 2010

Blacktip Project Operations

Manager

1.6 LEGISLATION AND GUIDELINES

The discharge will be regulated under the NT Waste Management and Pollution Control Act (Reference [5]). This Act is not prescriptive in terms of discharge parameters, however, ultimately it must be undertaken to the satisfaction of the Executive Director of Environment, Heritage and the Arts. To this end, Eni will work with the EPA Program to derive meaningful discharge parameters.

ANZECC and ARMCANZ (2000) (Reference [6] ) provides water quality guidelines for marine waters.




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2. PRODUCED WATER TREATMENT SYSTEM

2.1 PRODUCED WATER FLOW RATES

In the early years, water production from Blacktip will be low (32m3/day or 200 barrels of water per day (bwpd1)) and mainly consist of condensed (saturation) water. As the reservoir ages and more wells are brought online, free water inside the geological reservoir with the gas and condensate breaks through and water production increase to a predicted maximum of 780m3/day (5000 bwpd) (Figure 2.1).

Blacktip Predicted Produced Water Discharge Rates

0

100

200

300

400

500

600

700

800

07 08 09 10 11 12 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

Year

Pro

du

ced

Wat

er

Flo

w r

ate

(m

3/d

ay

)

Figure 2.1: Produced water production rates

2.2 TREATMENT SYSTEM

The PW Treatment System is detailed in the Design Philosophy Document [7]. It is designed to:

handle a maximum flowrate of 9,400bwpd (50% more than the anticipated water production rate); and

reduce the oil in water concentration to below 30mg/L.

Figure 2.2 shows a schematic for the system. The main components include a

Produced Water Flash Drum (PWFD);

Induced Gas Flotation unit (IGFU); and

Break Tank. 1 6.29 barrels = 1m3




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The PWFD receives water from the medium and low pressure separators. This vessel is maintained at a lower pressure than the separators, which encourages entrained gas to breakout and be removed. The degassed effluent is directed to the IGFU for further treatment. The IGFU removes traces of finely dispersed oil by bubbling gas through the water. Small oil droplets become attached to the surface of the bubbles and rise towards the surface where they accumulate. The accumulated layer is skimmed periodically and directed to the hazardous open drains. Effluent from the IGFU is pumped using low shear pumps to the break tank.

The break tank has a volume of 500m3 and, at maximum design rates, contains sufficient capacity to store up to eight hours of PW. Prior to discharge, the water is tested for Oil in water (OIW) concentration. Should the water not meet the required specification, it will automatically be recirculated back through the system. The storage capacity of the tank allows sufficient time to rectify any performance issues in the upstream equipment to bring the PW back to discharge quality.

Any hydrocarbons that separate during the time the water is in the tank will be skimmed and directed to the hazardous open drains. PW that meets the regulatory conditions will be pumped from the break tank to sea via a High Density Polyethylene (HDPE) subsea outfall pipeline. The pump is level controlled, turning on when the water level in the tank reaches 3.3m and turning off when the layer reduces to 0.65m. Level in the tank is kept low to ensure adequate buffer volume exists to store water in case of a performance upset. The pump will discharge at a fixed rate of 63m3/hr.

The end of the outfall pipe is located 2km offshore in approximately 12m of water (relative to Lowest Astronomic Tide (LAT)) (Figure 2.3). Effluent will be discharged through a four port diffuser (Figure 2.4). This will enhance mixing of the PW with the receiving waters immediately on release.




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Figure 2.2: Schematic of Produced Water Treatment System

Figure 2.3: Produced water discharge location




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Figure 2.4: Illustration of four port discharge diffuser

2.3 START UP

The PW treatment system shall be brought online during pipeline dewatering, prior to introducing hydrocarbons to the facility. PW for start up will be sourced by recycling from the break tank. This will ensure that the contents of the tank are not contaminated by “off-spec” water. Monitoring of OIW during this period will indicate when discharge can commence.

2.4 “OFF-SPEC” WATER

In the event of a process upset the system shall be designed to store “off-spec” PW, such that production can continue for between 8 – 24 hours, depending on the production rate. This will allow time to resolve process upset. Once the water meets discharge specifications, “off spec” water will be recycled through the treatment system.

MLWS

MSL

MHWS

17.3m

Condensate Export Pipe

PFW Pipe




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3. ENVIRONMENTAL RISK ASSESSMENT

3.1 COMPOSITION OF BLACKTIP PW

Based on knowledge of other PW in the region and also worldwide, Blacktip PW is likely to contain trace concentrations of:

dissolved oil;

organic acids;

heavy metals;

radioisotopes;

residual process chemicals.

Dissolved oil in PW is made up predominantly of:

aliphatics;

BTEX compounds;

low molecular weight Polycyclic Aromatic Hydrocarbons (PAHs).

Due to their solubility, these components will dilute readily into the receiving water and be dispersed by the ambient currents. They are also volatile and given the opportunity will preferentially partition into the gaseous phase, which means that they will evaporate on contact with the atmosphere. They do not adsorb strongly to suspended particles so are unlikely to be transported to the seabed.

PAHs are the petroleum hydrocarbon of greatest environmental concern in PW because of their toxicity and persistence in the marine environment (Neff 1987 [8]). The wide range of solubilities and partition coefficients exhibited by the different PAHs means that they exhibit a wide spectrum of behaviour [11]. Lower molecular weight PAHs (naphthalene, alkylnaphthalenes, fluorene and phenanthrene) are soluble and therefore end up in the produced formation water. Higher molecular weight PAHs are less soluble and are expected to remain in the oil phase and should not be discharged with the PW. Studies undertaken by Woodside only ever detected low concentrations of napthalene (0.670mg/L), phenanthrene (0.0180mg/L) and fluorene (0.021mg/L). Biodegradation half lives range from 1.5 days for naphthalene, 17 days for two to three ring PAHs and 350 days for more than four ring PAHs [9].

Bioaccumulation Potential: Aliphatic hydrocarbons and BTEX compounds have a very low potential for bioaccumulation. In contrast, there is moderate potential for the low molecular weight PAHs to bioaccumulate. However, concentrations of PAHs in the receiving waters for Blacktip with dilute rapidly and remain low enough to prevent this occurring.

PW may contain high concentrations of phenol and alkyl phenols. Phenol is a natural ingredient of the ocean being synthesised by a wide variety of plants and microbes. It is also a product of plant material degradation. These compounds are highly soluble and will dilute and degrade rapidly following discharge of PW to the ocean. The combination of dilution, bio– and photo-degradation and evaporation will produce a rapid decline in dissolved phenol concentrations in the water column with distance from the PW discharge. It is unlikely that marine organisms would encounter concentrations




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above the toxic threshold. Phenol does however have the potential to impart taint and odour to edible tissue at relatively low concentrations. Concentrations that will be found in the receiving waters for Blacktip will be below the level likely to cause taint.

Organic acids biodegrade rapidly in the ambient sea water and so are unlikely to be important contributors to toxicity of PW in the ambient environment (Neff 2002 [11]). Natural seawater is a buffer solution and acidity will be quickly neutralised. Organic acids are therefore not considered to be toxic in the marine environment.

Heavy metal concentrations are generally low in PW and are generally present as dissolved mineral salts. Reservoir water is anoxic and the metal ions are typically in low oxidation states. However, when brought to the surface and exposed to the atmosphere they oxidise. The metal oxides then combine with anions such as sulphides, carbonates and chlorides and form insoluble precipitates.

Dilution in the receiving environment reduces them to background levels and well below chronic toxic thresholds. When they form precipitates, there is the potential for build up in the sediments, however, the quantity will be so low and the spread across the seabed so wide that the environmental impact will be insignificant.

Upon discharge of PW to the ocean, radium is rapidly co-precipitated with barium sulphate. Radium concentrations in ambient water near PW discharges are rarely higher than background levels. Toxic concentrations are well above the saturation concentrations of radium in sulphate-rich seawater. Marine animals are highly tolerant to low-level radiation as might occur in the traces of radium isotopes in the vicinity of PW discharges. Radium, because of its low concentration in solution in seawater, has a low bioavailability to marine organisms. There is also no evidence that radium accumulates in sediments or marine animals (molluscs, crabs and fish) living in the vicinity of offshore PW discharges [11].

Process chemicals planned for the gas plant are:

Corrosion inhibitor;

Methanol/Mono Ethylene Glycol;

Demulsifier/coagulant.

Corrosion Inhibitor will be added to the produced fluids in order to protect the production system from corrosion. This preparation usually consists of a cationic surfactant compound. As such it will have a combined lipophilic/hydrophilic structure which gives it the tendency to adsorb to surfaces and to collect at aqueous/organic-phase boundaries.

Corrosion inhibitor is water soluble, however, most of it will react in the process system and only a small proportion (conservatively estimated at 10% [12]) will end up in the PW discharge. On discharge to the marine environment, dilution will be the main factor reducing concentrations in the short term. Surfactants are inherently biodegradable so should not persist in the environment.

Methanol (or possibly Mono Ethylene Glycol) will be injected upstream of the chokes on the offshore wellhead platform to prevent hydrate formation on cold start-ups. The injection rate will be around 20-40 L/hr for a short duration (hours). Methanol may also be injected at the OGP in the gas processing facility for hydrate control. This would likely be injected only occasionally upstream of the Low Temperature Separator (LTS)




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and so some will remain in the liquid leaving the LTS and end up in the condensate processing train, and therefore the water treatment process.

Methanol is miscible in water, non-carcinogenic and poses little long term risk to the environment. It is, however, a strong reducing agent and, in the short term, has the potential for depleting oxygen in the receiving waters. This will not be a problem due to the relatively small volumes being discharged and the high oxygen levels in the receiving waters.

Demulsifier/coagulant will be injected in the water treatment facility to aid in the operation of the IGFU. This is generally a low molecular aromatic hydrocarbon product. Most, if not all, of this will partition into the oil phase and be removed as skimmings from the various units. It will not therefore enter the PW.

3.2 ASSESSING ENVIRONMENTAL EFFECTS AND RISKS

3.2.1 General

An effect on an organism is a measurable biological response which reduces its survival or reproductive capacity. A sustained widespread effect may alter the ability of a population or a community to persist. The ecological significance of an effect may be considered in terms of the magnitude and nature of the change induced at individual, population, community or higher trophic levels. The social and economic significance of effect can be considered in terms of impact on recreational or commercial fishing, tourism, conservation values and the benefit to the community of the petroleum industry (Reference [10]).

3.2.2 Toxicity

Toxicity depends on the chemical compounds present, the exposure duration (acute or chronic), the organisms impacted and the environmental compartment. Most hydrocarbons are considered non-specific narcotic toxins and their toxicity depends on attainment of a critical volume or concentration in the tissues of aquatic organisms [11]. The toxicity of hydrocarbons in mixtures is additive, so the toxicities of a complex mixture depends on the total concentration of bioavailable hydrocarbons and degradation products in the water to which aquatic organisms are exposed.

Acutely toxic responses have a sudden onset after or during relatively high exposure usually for short durations: within four days for fish and macroinvertebrates and shorter times (2 days) for organisms with shorter life spans. The response may be lethal or non-lethal. In contrast, chronic responses involve endpoints that are realised over a relatively long period of time, often one-tenth of the life span of an organism or more. A chronic toxic response is usually characterised by slow toxic progress and long continuance and may be measured in terms of reduced growth, reproduction or fertilisation at different life stages, in addition to lethality.




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Toxic concentrations are standardised as LC50s for lethal responses or EC50s and IC50s for non-lethal response. Definitions for these terms are as follows:

Lethal response

LC50 The toxicant concentration killing 50% of exposed organisms at a specific time of observation.

EC50 The toxicant concentration estimated to cause a specified effect in 50% of exposed organisms at a specific time of observation.

Sub-lethal response

IC50 The toxicant concentration estimated to cause a specified inhibition (eg. growth) in 50% of exposed organisms at a specific time of observation.

PW from oil and gas wells vary widely in composition and toxicity to freshwater and marine organisms, confounding the development of generalisations about the causes of toxicity (Reference [11] ). This uniqueness makes it necessary to undertake site specific studies. In estimating the risk of PW to marine organisms and ecosystems in the receiving water environment there are two different approaches:

whole effluent toxicity (WET) testing; and

individual component toxicity testing.

Whole Effluent Toxicity Testing

As its name suggests, WET testing involves undertaking ecotoxicological tests on the whole PW sample. This method represents a toxicity value for the PW prior to discharge to the ocean. It has the advantage that it is directly relevant to the effluent that is being discharged and it takes into consideration all chemicals in the PW and any synergy or antagonism between them. The disadvantage is that degradation rates in the environment are unknown and are difficult to determine.

Table 3.1 presents a summary of PW toxicity data for a large number of marine and freshwater organisms and PW from throughout the world. Due to the extreme variability in chemical composition and toxicities of the PW from different sources, no consistent trends between taxa and sensitivity to PW emerge. Acute and sublethal effect concentrations (as EC50 and LC50) ranges from 0.02 to more than 100%. Overall the most sensitive taxa appear to be marine algae, bivalve mollusc larvae, and various species of crustaceans, particularly larval forms. Among the crustaceans, mysids appear to be as or more sensitive than other crustacean species. Generally, fish are more tolerant to PW than marine invertebrates.

Table 3.2 summarises tests undertaken on PW samples collected from Woodside facilities on the North West Shelf and Timor Sea (Reference [2]). Results are presented in Figure 3.1 and Figure 3.2. Individual tests target toxicity of different components in the PW, hence results, both between tests and facilities are quite variable.




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Table 3.1: Summary of the acute, sublethal and chronic toxicity of PW from throughout the world to different taxa of marine and freshwater organisms (Reference [11])

Taxon Species Test Endpoint Test

Duration

(days)

EC50/LC50

(%PW)

Algae Phaeodactylum tricornutum

Skeletonema costatum

Growth

Growth

4

2

3

0.09 – 3.6

4.5 – 67.6

1.0 – 42.5

Coelenterates Campanularia flexuosa Growth 10 5.0

Bivalve Molluscs Crassostrea gigas larvae

Mytilus californianus larvae

Donax faba adults

Mortality

Shell formation

Mortality

2

2

4

5.0

2.1

0.02 – 15.3

Polychaetes Neannthes arenaceodentata Mortality 4 18.1 – 28.6

Copepods Tisbe holothuriae

Calanus finmarchicus

Arcatia tonsa

Mortality

Mortality

Mortality

Reproduction

Immobility

4

1

2

20

4

35.7 – 66.7

10.0

2.0 – 18.0

0.3 – 5.0

2.0

Amphipods Allorchestes compressa

Chaetogammarus marinus

Mortality

Mortality

4

4

29.4 - >100

0.2 – 3.2

Shrimp Penaeus aztecus larvae

Penaeus aztecus juveniles

Penaeus aztecus adults

Penaeus setiferus adults

Crangon crangon adults

Mortality

Mortality

Mortality

Mortality

Mortality

2

4

4

4

1

0.8 – 1.2

6.0 – 18.3

7.8 – 17.8

7.0

2.0

Mysids Americamysis bahia Mortality

Mortality

Fecundity

4

7

7

4.9 – 11.8

4.4 – 9.0

0.7 – 7.0

Brine Shrimp Artemia salina Mortality 1 16.0 – 18.0

Barnacles Balanus tintinabulem Mortality 4 8.3

Echinoderms Strongylocentrotus Purpuratus

gametes

Fertilisation 1 hour 0.74 – 1.7

Fish Menidia beryllina larvae

Hypleurochilus germinatus

Cyprinodon variegaus

Poecilia reticulata

Oncorhynchus mykiss

Mortality

Mortality

Mortality

Mortality

Mortality

Mortality

4

4

4

7

4

2

>1.1 – 5.5

15.8 – 40.8

7.2 – 60.0

3.7 - >28.0

0.75 – 42.3

10.0




Page 23 of 50

Table 3.2: Summary of ecotoxicological tests undertaken of PW samples collected from Woodside facilities on the NWS (Reference [2])

Taxon Test Species

Test Endpoint

Duration Endpoint Value

(hours)

5 mins. EC50

15 mins. EC50

30 mins EC50

5 mins. NOEC

15 mins. NOEC

30 mins NOEC

5 mins. LOEC

15 mins. LOEC

Bacteria (microtox

test) Vibrio fischeri

Decrease in light output

30 mins LOEC

IC50

NOEC Algae Isochrysis aff.

Galbana Growth/cell yield 96

LOEC

EC50

NOEC Rock Oyster

Saccostrea

commercialis Larval development 48

LOEC

LC50

NOEC Tiger Prawn Penaeus monodon Survival 96

LOEC

EC50

NOEC Sea Urchin

Heliocidaris tuberculata

Fertilisation success 1 hour exposure + 15 minute

fertilisation LOEC

EC50

NOEC Sea Urchin

Heliocidaris tuberculata

Larval development 72

LOEC Notes: NOEC: No Observed-Effect Concentration; LOEC: Lowest Observed-Effect Concentration.




Page 24 of 50

Comprison of EC/IC/LC50s between facilities

0

5

10

15

20

25

30

35

40

45

CossackPioneer

Goodwyn(Unfiltered)

Goodwyn(Filtered)

North Rankin(Filtered)

North Rankin(Unfiltered)

NorthernEndeavour

Ocean Legend

EC

/IC

/LC

50 (

% P

FW

)

Sea urchin fertilisation success test

Sea urchin larval development test

Rock oyster larval development test

Juvenile tiger prawn acute toxicity test

Isochrysis algal growth inhibition test

Figure 3.1: Ecotoxicology results for Woodside’s North West Shelf and Timor Sea Assets

(from Reference [2])

Microtox Acute Test

0

5

10

15

20

25

30

35

EC

50 (

% P

FW

)

EC50 5min 12 3.6 3.6 1.3 1.3 21 4

EC50 15min 12 4.5 4.5 1.4 1.4 29 4.6

EC50 30min 14 5.3 5.3 1.5 1.5 33 5.4

Cossack Pioneer Goodwyn

(Unfiltered)Goodwyn (Filtered)

North Rankin (Filtered)

North Rankin (Unfiltered)

Northern Endeavour

Ocean Legend

Figure 3.2: Comparison of Microtox® test results between facilities (from Reference [2])




Page 25 of 50

Individual Component Toxicity Testing

Individual component toxicity testing involves characterising the PW for its individual component concentrations and then comparing these with values below which it is believed that there will be no detrimental effect on the environment. This latter value is referred to as the predicted no effect concentration (PNEC). The advantage of this method is that the toxicity and behaviour of individual chemicals in the receiving environment is known and the fate and effect in the marine environment can be predicted more accurately. The disadvantage is that the PW is an extremely complex mixture containing many different organic compounds. These are difficult to determine in the laboratory and they do not all have PNEC values associated with them.

3.2.3 Tainting

When present in foods, petroleum hydrocarbons stimulate an olfactory response that can cause a tainting of taste. Tainting is said to occur in fish when they are exposed to ambient concentrations of 4 to 330 ppm and in filter feeders, such as oysters, when they are exposed to concentrations as low as 10 ppb (Reference [1]), though this is dependent on exposure periods.

3.2.4 Risk Assessment

The ratio of the Predicted Environmental Concentration (PEC) to the PNEC (PEC/PNEC ratio) is an established technique to screen chemicals in offshore discharges. It forms the basis of the OSPAR Harmonised Notification Scheme (Reference [12] ) and is used in the Environmental Impact Factor (EIF) tool (Reference [13]). The PNEC relies upon the assumption that a single value captures the concentration at which no toxic response (acute or chronic) is expected in the target population of marine biota. Dispersion models, such as that used in the present study (see Section 3.3), provide spatially and temporally varying PECs for either the whole effluent of individual compounds. A PW plume with a PEC/PNEC ratio of one will generally correspond to a probability of 5% that biota will be affected.

Based on the Woodside results (Figure 3.1), a PNEC of 0.1%PW has been set for the Blacktip PW.

3.3 ENVIRONMENTAL IMPACT

3.3.1 Marine habitats

Coastal habitats in the vicinity of the discharge include:

pelagic;

benthic; and

intertidal zones

Section 7 and Appendix B of the EIS (References [1] and [2], respectively) provides a detailed description of the various habitats. A summary is provided below.

Pelagic zone

The pelagic habitat support: marine mammals, fish, reptiles invertebrates; phyto – and zooplankton. Whales and dugongs are not expected to be common inhabitants of the




Page 26 of 50

Joseph Bonaparte Gulf. Dugongs are patchily distributed throughout tropical and subtropical waters of the Indian and Pacific Oceans with major concentrations of dugongs coinciding with sizeable seagrass beds, on which they feed. The lack of seagrass in Joseph Bonaparte Gulf is expected to limit the distribution of dugong's, though anecdotal evidence reported by local Aboriginals suggests that dugongs can occur between Cape Hay and Point Pearce. A number of dolphins have wide distributions and are expected to occur within the Joseph Bonaparte Gulf including the Irrawaddy dolphin, the spotted bottlenose dolphin, Risso's dolphin, Indo-Pacific humpback dolphin and pantropical spotted dolphin.

Reptiles in the Joseph Bonaparte Gulf include: turtles, saltwater crocodiles, the mangrove snake; and the mangrove monitor. Significant flatback turtle breeding and nesting sites are documented on the north side of Cape Domett in the inner, western Joseph Bonaparte Gulf and anecdotal evidence suggests that they may historically have nest on sandy beaches to the north of the pipeline landfall. However, discussions with Wadeye Elders indicate that turtles have not nested in any number following a beach recession event about 15 years ago.

Generally high densities of crocodiles occur in tidal portions of mangrove-lined rivers, particularly those associated with extensive freshwater wetlands or floodplains. However, studies on crocodile populations in the Victoria and Fitzmaurice Rivers suggest that the project area is not significant for crocodile populations. Nesting sites are limited and recruitment rates are generally low. Crocodiles are however reported to be in the upper reaches of most rivers and creeks around the Wadeye area.

Sea snakes are very common in subtropical and tropical Australian waters and occupy a wide range of habitats and water depths, extending offshore from the coast to the reefs and banks of the Sahul Shelf. Although there are no records of their specific occurrence in the Joseph Bonaparte Gulf, sea snakes are expected to be very common, with as many as fifteen species known to occur in the Northern Territory.

Benthic Zone

Appendix A2 presents a figure showing the seabed characteristics long the pipeline route. In the vicinity of the PW outfall, the seabed consists of coarse sand and gravel. Figure 3.3 to Figure 3.5 show examples of sediment samples collected from the sea bed during the geophysical survey [14]. Further inshore and offshore the seabed contains weaky indurated patches of gravel and coralline debris. A variety of benthos are supported in the area including crustaceans, bryazoans, hydroids, polychaetes, molluscs, exchinoderms, sponges, sea cucumbers and scattered coral colonies. Large terrigenous inputs and resuspension by large tides limit the development of significant coral reefs, large seagrass beds or macroalgal beds. The coarse sediment also limits the development of a deposit feeding community [2].




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Figure 3.3: Example of seabed sediment inshore of the PW discharge

PW discharge location




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Figure 3.4: Example of seabed sediment offshore of the PW discharge





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Figure 3.5: Example of seabed sediment offshore of the PW discharge





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Figure 3.6 Example of seabed sediment offshore of the PW discharge





Page 31 of 50

Intertidal zone

The intertidal zone includes

beaches;

rocky coastlines; and

mangroves

Northern Yelcher Beach is fringed with a steep sand dune to 2 m high. Below the beach dune but above the high spring tide level the beach is gently sloping and composed of very coarse sand with coral fragments and rock. Timber, mangrove leaves and other flotsam and jetsam are abundant in this habitat, though no drift seagrass or macroalgae have been observed. These flotsam and jetsam provide shelter for high densities of the terrestrial hermit crab Coenobita variabilis (up to 80 hermit crabs per m2). This species is known to extend up to 100 m or so from the beach (Jones and Morgan 2002).

The Yulow Point rock platform at the south of Northern Yelcher Beach comprises a flat lateritic point that extends approximately 400 m from the beach. It is relatively steep sided and flanked with an extensive area of lateritic boulders, up to 100 m wide to the north and standing water and mangroves to the south. The distribution of the biota is highly variable reflecting microtopography. However, visual assessments indicate that the more seaward section of the rock platform supports a higher diversity and abundance of invertebrate fauna, including sparse corals, anemones, chitons and larger crustaceans than the nearshore sections. No macroalgae has been observed.

The Yulow Point mangroves to the south of Northern Yelcher Beach form a strip less than 700 m long and between 100 to 300 m wide. The mangrove habitat at this location is extremely sandy with muds only occurring in the most seaward zone. The mangrove forest is quite sparse with well-spaced trees and a relatively open canopy. This contrasts with the extremely dense mangroves to the north of the shore crossing, which have a muddy to gravely substrate.

The mangroves occurring on Maninh Point, to the north of northern Yelcher Beach, have a substrate comprising firm, root-structured marine muds. The muddy substrate becomes gravelly to rocky where it abuts the surrounding intertidal rocky habitat. It contrasts markedly with the sandy mangrove habitat at the southern end of northern Yelcher Beach. The mangrove forest at Maninh Point is taller and more dense. The mud mangrove substrate supports a different invertebrate fauna with several species recorded in the northern mangrove area (including the large molluscs Terebralia palustris, T. semistriata and) were not observed in the southern forest.

3.3.2 Dispersion modelling

Prior to discharge, the OIW concentration of the PW will be reduced to a maximum of 30mg/L. Whilst the concentration is relevant to the environmental impact, the load of contaminants being discharged is more important. In the early years of production from Blacktip, it is anticipated that just 200 barrels of water per day (bwpd) will be produced. The water will be stored in the break tank and batch discharged when the level in the tank reaches 3.3m. This will result in a volume of 252m3 being discharged at a rate of 63m3/hr once every eight days. Figure 3.7 presents an example of the predicted PW concentrations at various stages of the tide for this scenario. The




Page 32 of 50

associated time series at 50m from the discharge and at various beach locations are shown in Figure 3.8 and Figure 3.9, respectively.

The diffuser on the end of the outlet pipe will enhance dilution in the near field zone (the waters immediately surroundings the discharge). The density of the PW is less than the receiving waters and on release it rises to the surface under its own buoyancy. It then mixes horizontally and vertically with the surrounding waters whilst being advected away from the discharge location by ambient currents.

It has been estimated through initial dilution modelling that the plume will achieve a minimum of 1:700 dilutions, reducing the concentration of the PW immediately to 0.14%PW. This increases to 1:5000 when tidal currents increase during mid and ebb tides. As shown in Figure 3.7 and Figure 3.8 the plume tends to pool at slack waters with concentrations peaking at 0.4%. With increased tidal flow, initial dilution also increases and concentrations reduce to well below the estimated PNEC value of 0.1%PW). The model predicts intermittent blips along the coastline at concentration of less than 0.01%PW (Figure 3.9). This equates to oil concentrations of below 3ppb, which is well below concentrations that could possible cause environmental harm.

After five years of production, water production is anticipated to increase to a maximum of 6000bwpd. The rate of discharge will remain the same (63m3/hr) but the duration of batch release will increase to about 16 hours every 24 hours (ie a break of 8 hours between releases). Model results for this scenario are presented in Figure 3.10, Figure 3.11 and Figure 3.12. Concentrations are about the same as seen previously for the 200bwpd discharge, however the time series reflect the more continuous nature of the discharge.

3.3.3 Impact on biological communities

Biological communities that could potentially be affected by the PW discharge include:

plankton;

sessile marine invertebrates (shellfish, seaweeds, seagrass etc.);

benthos;

fish;

marine mammals; and

sea birds.

Planktonic organisms live freely in the water column and drift with the water currents. Plankton may also include the early stages (eg. egg, larva and spores) of non-planktonic species (fish, benthic invertebrates and algae). Figure 3.13 illustrates the typical exposure periods for passive floating organisms. Once discharged to the receiving environment, dilution reduces the concentration of toxic chemicals in the PW. For a worst-case scenario, a freely floating organism passing directly beneath the discharge pipe may be exposed to PW concentrations above the PNEC value for up to three hours. There is therefore the potential for impact, however, the exposure concentration will be continually diluting and only organisms residing directly in the plume would be impacted, which constitutes a small proportion of the community.

Concentrations of the PW in the receiving environment are not high enough to be acutely toxic to fish and there were no chemical components that would bio-accumulate or magnify. Moreover, vertebrates including fish have detoxification mechanisms that




Page 33 of 50

break hydrocarbon compounds down. Figure 3.13 shows the typical exposure periods for motile organisms such as fish. These have the ability to swim and might move in and out of the plume. Exposure periods are therefore sporadic and unlikely to be at levels which would harm or taint the organism. Moreover, the volume of water exposed to concentrations above PNEC values is relatively small both under present and projected discharge rates.

Benthos communities are found in or around the seabed. They are unlikely to be affected because the plume disperses rapidly in the water column and does not impact directly on the seabed. Furthermore adsorption onto suspended sediment particles will be low, limiting the extent of sedimentation to the seabed.

As marine mammals feed on fish and/or plankton, they could potentially be affected by trophic transfer (i.e. bioaccumulation of chemicals from food) and potential biomagnification. However, vertebrates are able to metabolise and excrete the type of chemicals that contribute most to the risk. They are also generally migratory so individuals are not likely to be affected by any localised contamination that may occur.

Seabirds are harmed mainly by the physical properties of floating oil and not the toxicity. (Reference [15]). As with the marine mammals, there is the potential for trophic transfer and indirect effects such as changes in the availability of food sources. As the food source is not likely to be impacted, the risk to sea birds is low.

In summary, it is possible that there could be a localised impact to the sessile marine communities in the immediate vicinity of the outlet, however, contamination would be mitigated by continual flushing of the receiving waters and the spatial and temporal variability of the PW plume. Beyond the immediate vicinity of the discharge, dilution alone will be sufficiently high to reduce contaminant concentrations to a level below which there could possibly be any adverse environmental impact.




Page 34 of 50

Note: Plume concentrations are in the range 0.01 – 0.1%PW. This is well below the concentration expected to result in any environmental effect.

Figure 3.7: Predicted PW concentrations during a neap and light onshore winds for water production of 200bwpd




Page 35 of 50

Neap Tide, Transitional SeasonConcentrations of PW at 50m from discharge location (in any direction)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Time (days)

PW

Co

nc

entr

ati

on

(%

PW

)

0

0.1

0.2

0.3

0.4

0.5

0.6

OIW

Co

nc

entr

ati

on

(m

g/L

)

%PW

OIW (mg/L)

Figure 3.8: Time series of predicted PW concentrations at 50m from the discharge location for water production of 200bwpd (neap tides and light onshore winds)

Neap Tide, Light Onshore WindsPW Concentrations at various beach locations

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Time (days)

Co

nc

entr

ati

on

(%

PW

)

Manninh Point

N Yelcherr

Yullow Point

Injin

S Yelcherr

Tchinidi

Figure 3.9: Time series of predicted PW concentrations at various beach locations for water production of 200bwpd (neap tides and light onshore winds)




Page 36 of 50

Note: Plume concentrations are in the range 0.01 – 0.1%PW. This is well below the concentration expected to result in any environmental effect.

Figure 3.10: Predicted PW concentrations during neap tide and light onshore winds for water production of 6000bwpd




Page 37 of 50

Neap Tide, Light Onshore WindsConcentrations of PW at 50m from discharge location (in any direction)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Time (days)

PW

Co

nc

entr

ati

on

(%

PW

)

0

0.1

0.2

0.3

0.4

0.5

0.6

OIW

Co

nc

entr

ati

on

(m

g/L

)

%PW

OIW (mg/L)

Figure 3.11: Time series of predicted PW concentrations at 50m from the discharge location for water production of 6000bwpd

Neap Tide, Light Onshore WindsPW Concentrations at various beach locations

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Time (days)

Co

nc

entr

ati

on

(%

PW

)

Manninh Point

N Yelcherr

Yullow Point

Manninh Point

S Yelcherr

Tchinidi

Figure 3.12: Time series of predicted PW concentrations at various beach locations for water production of 6000bwpd




Page 38 of 50

Co

ncen

tra

tion

Time

Motile organism

Passive floatingorganism

A/B B' A'

AA'

B B'

PNEC

DischargeLocation

Dispersion of PFW plume

Figure 3.13: Exposure times to the PW plume for passive and motile organisms




Page 39 of 50

3.4 SUMMARY

A complete summary of the environmental risk assessment is presented in Table 3.3.

Table 3.3 Environmental Risk Summary – Produced Water

RISK ASSESSMENT

Risk Element Details Conclusion

Environmental Impact

Chronic ecotoxicity to marine organisms, adverse effects on water quality in the immediate surrounds of the PW outlet.

Likelihood Assessment

PW will be discharged to sea throughout normal operations. Effects on the environment immediately surrounding the PW outlet are a possibility.

Possible

Consequence Assessment

It is possible that there could be a localised impact to the biological communities in the immediate vicinity of the outlet, however, contamination would be mitigated by continual flushing of the receiving waters and the spatial and temporal variability of the PW plume. Beyond the immediate vicinity of the discharge, dilution will be sufficiently high to reduce contaminant concentrations to levels below which they could possibly cause any environmental harm.

Minor effect

Risk Ranking MEDIUM

RISK MITIGATION MEASURES

Monitoring

M-1 OIW content of PW will be monitored prior to discharge. Continuous monitoring is being investigated.

Procedural/ Management

P-1 Concentration of OIW discharged to sea does not exceed 30 mg/L

P-2 Ecotoxicity tests will be conducted on PW.

P-3 Dilution rates will be high and contaminant concentrations will be low. Contaminants are expected to biodegrade readily and no compounds have been identified with potential for bioaccumulation.

P-4 Oil concentration in the receiving water will be too low for tainting

Engineering Controls

S-1 Equipment for monitoring of OIW from the PW stream will be regularly calibrated and tested.

S-2 PW discharge volumes will be measured.

S-3 PW exceeding the set discharge criteria will be recirculated through the system before eventual discharge to sea.

S-4 A four port diffuser will be used to enhance dilution in the near field.




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4. PRODUCED WATER STUDIES

4.1 OVERVIEW

Once PW becomes available, samples will be taken to analyse for:

chemical characteristics;

ecotoxicity and

biodegradation; and

bioaccumulation potential.

Studies will be undertaken as soon as a PW sample becomes available. The frequency of this sampling and the reporting will be undertaken in accordance with the Blacktip Environmental Protection Licence (EPL 57 (formerly EPL-LNG02)) (see Appendix A3). The following provides a brief overview of each study.

4.2 CHEMICAL CHARACTERISATION

The objective of the chemical characterisation will be to gain a better understanding of the PW composition. Target analytes and their method of measurement are listed in Table 4.1. Risk will be assessed against the ANZECC water quality guidelines (Reference [6] ).

Table 4.1: Target analytes for chemical characterisation and their method of measurement

Analyte APHA/USEPA Reference pH APHA 4500-H+ Electrical Conductivity APHA 2520 B Total Dissolved Solids APHA 2540 C Total Suspended Solids APHA 2540 D Turbidity APHA 2130 TOC APHA 5310 B Total oxidised nitrogen APHA 4500-NO3- F Ammoniacal nitrogen (NH3-N) APHA 4500-NH3 G Total nitrogen APHA 4500-Norg Soluble metals (flame AAS) APHA 3111/3500 Mercury APHA 3112/3500 Speciated Phenols USEPA 8270 modified Total Petroleum Hydrocarbons (TPH) USEPA 3510B, 8015B Volatile TPH C6 to C9 USEPA 5030A, 8020A, 8015B BTEX USEPA 5030B, 8020A, 8260 PAHs USEPA 3550B, 8270 Aliphatic/aromatic split EPA (Massachusetts) 1998 Surfactants TBD

4.3 WHOLE EFFLUENT TOXICITY TESTING

The objective of the ecotoxicology study component will be to determine the chronic and acute toxicity of the whole PW. A number of lethal and sublethal tests will be




Page 41 of 50

undertaken on a range of marine organisms covering at least three trophic levels. Typical tests might include (see Table 3.2):

Microtox®;

algal growth inhibition;

rock oyster larval development;

juvenile tiger prawn acute toxicity;

sea urchin fertilisation; and

sea urchin larval development.

Results from these tests will be used to estimate the PNEC for the effluent (see Section 3.2.4). This concentration can be related back to the modelling results to determine a potential zone of effect for the PW.

4.4 BIODEGRADATION

Biodegradation tests will be undertaken to test the hypothesis that PW becomes less toxic with time. To this end, PW will be sampled and stored in conditions that would represent natural weathering (i.e. mixed with natural seawater and exposed to the atmosphere and sunlight). Microtox® tests and TRH analysis will be undertaken at predefined times after collection to determine the change in ecotoxicity and chemical composition.

4.5 BIOACCUMULATION

The objective of this study would be to assess the bioaccumulative capacity of the PW. To this end, selected bivalve species would be exposed to PW in a tank. After 28 days a subsample of the bivalves would be tested for hydrocarbon and heavy metal concentrations. The remainder would be left in the tank and flushed with clean seawater for a further 28 days. After this time, the shellfish would be tested to assess the ability of the bivalve species to depurate.

4.6 MARINE MONITORING

Any assessment of PW effects and risks should consider acute and chronic effects as Blacktip will have an operating life of up to 25 years or more. Chronic effects are notoriously difficult to measure in the natural environment. It is anticipated that contaminant concentrations in the receiving waters will be below detection limits and the only way contamination could be identified is through accumulation in sediment and bioaccumulation in marine organisms. Accumulation is most likely to occur in sediment with some organic content. For example, during the marine survey undertaken in 2004 hydrocarbons were detected at low levels in Yullow Point mangrove sediments. The source of the contamination is thought to be natural seeps or fallout from regional bush fires. Bioaccumulation is most likely to occur in filter feeding marine organisms. Detection will provide an early warning of exposure to contamination.

The following is proposed for the annual marine monitoring:

Offshore sediment sampling in the vicinity of the discharge.




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Onshore sampling of sediment and shellfish at stations located around the immediate coastline (Figure 4.1).

Samples will be taken in triplicate and subsequently analysed for hydrocarbons and heavy metals.

A baseline survey will be undertaken prior to discharge of PW. Thereafter sampling will be undertaken on an annual basis or more frequently should any traces of contamination be detected.

The Commonwealth Department of Environment, Water, Heritage and the Arts (DEWHA) and the Northern Territory Department of Natural Resources, Environment, the Arts and Sport (NRETAS) will be consulted on the sampling and analysis method for the sediment sampling program two months prior to undertaking the surveys. Copies of the investigation report will be submitted to both government Departments within one month of completion of the surveys.

Figure 4.1: Proposed monitoring locations

Mangrove mud/shellfish

Beach shellfish

Rocky platform shellfish




Page 43 of 50

5. TRIGGER FOR CORRECTIVE ACTION AND CONTINGENY

The chemical characterisation, ecotoxicology, biodegradation and bioaccumulation studies cannot be undertaken before a PW sample becomes available, which is not until production commences. It should take approximately 2 – 3 weeks to turn around the first three studies so it should be feasible to undertake these prior to discharge. The bioaccumulations study will take in excess of 10 – 12 weeks to complete. As there is limited storage on site the results from the bioaccumulation study might have to be reported after discharge commences. The chemical characterisation, ecotoxicology, biodegradation studies should provide sufficient information on the nature of the discharge and its likely impact on the marine environment.

In the unlikely event that the samples:

contain contaminant concentrations which exceed the trigger levels given in the ANZECC water quality guidelines (for 99% species protection) multiplied by a factor2 to allow for dilution within an agreed mixing zone (eg 50m from the discharge); and/or

have a high PW toxicity (eg. PNEC value of less than 0.1%PW), then

this will be reported to the NT and Commonwealth Government departments, together with a plan for rectifying the situation, within 2 weeks of receiving the results. Depending on the nature of the contamination, an assessment will be made on whether the effluent is suitable for short term discharge whilst a long term plan is put in place.

Contingencies to rectify the situation might include tuning the existing treatment equipment or retrofitting addition treatment equipment to remove the identified contaminants. This equipment will not be fitted during construction of the OGP, as water production in the first year is minimal and the exact nature of the PW prior to start-up is unknown. The retrofit strategy will allow Eni to more accurately target the contaminants causing the problem.

Cartridge filter and adsorption media are examples of equipment that could be retrofitted to remove free and dissolved hydrocarbons. Cartridge filters consist of a number of cartridge elements contained in a single pressure vessel. Water is passed from the inside to the outside of the elements collecting contaminants inside the cartridges. Separation efficiency is entirely dependant on the oil particle size distribution compared with the pore size of the filter. Typical performance would be 98% removal at 2µm. With selection of the correct filter media, there is also potential to remove the dissolved hydrocarbon content of the water.

Adsorption Media uses through-flow filtration. As fluid passes through oil adsorbs onto the surface of the media. This technology has the capacity to remove both free oil and dissolved hydrocarbons leaving a waste stream free from contamination. The device can be very similar to a cartridge filter in that a number of cartridges can be housed in a single pressure vessel.

Over the longer term, the marine monitoring program will measure any adverse affects in the marine environment. This will be undertaken annually and reported to the government departments in the Annual Environmental Performance Report. This

2 Modelling predicts that a minimum of 700 dilutions would be received in the near field.




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report will be based on data collected over the period 1 July to 30 June inclusive and shall be submitted prior to 1 August. Should any contamination be detected that was not present in the baseline monitoring program, an investigation will be undertaken to determine the cause. Should the results of the investigation indicate that the cause of the contamination be related to the PW discharge then appropriate corrective measures will be put in place.




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6. INDUSTRY BEST PRACTICE

6.1 COMPARISON WITH OTHER GAS PLANTS

Karratha gas plant discharges waste water into the Mermaid Sound from a licenced outfall approximately 200m offshore. Approximately 240m3 is discharged twice a week over a 30 minute duration (i.e. 8m3/min for 30 mins). Chemical characteristic of the discharge are measured regularly and marine monitoring is undertaken annually. No adverse effects have been measured.

Four oil and gas processing facilities have been built on islands on the North West Shelf of Western Australia (none on the mainland). Three of these discharge or have discharged into the nearshore marine environment:

Barrow Island: PW is injected into a deep ground water reservoir.

Thevenard Island: PW is reinjected into a depleted reservoir but was previously discharged in the vicinity of the nearshore environment, just off the coast of Thevenard Island.

Varanus Island: PW from a number of wells is injected into deep groundwater reservoir below the island. PW from the nearby Harriet Field is discharged at an offshore platform located about 6 km from the nearest islands of the Lowendal Island group.

Airlie Island: The facility is currently mothballed. However, when operational, PW was discharged in the nearshore environment, just off the coast of Airlie Island.

The remaining facilities in northern Australia are located further offshore and discharge PW directly to sea.

Recently, three similar onshore gas plants have been developed or are in the process of being developed in Victoria. Under Victorian legislation, the discharge of PW in coastal waters is controlled by the State Environment Protection Policies (Waters of Victoria) 1988 which applies within 3 nm of the coast. The discharge of PW in coastal waters is not prevented in coastal Victorian waters; however, the level of treatment required varies according to distance from the coast.

Of the new facilities in Victoria:

Otway Gas is a Woodside development off the Otway coast. PW rates from this development will peak at 320 m3 per day, compared to over 1120 m3 per day for the Blacktip Project. Nearshore disposal was considered during the early phase of the project but, given the small volumes of PW, recharge of the deep Waarre aquifer was selected as the preferred option.

The Casino gas field is a Santos development. This development will utilise the existing TXU-owned Iona gas facility which has an onshore PW treatment to process the small quantities of PW generated.

The Minerva development is operated by BHP. It uses thermal oxidation (burning) to dispose of its small quantities of PW.

The Blacktip gas field generates significantly greater quantities of PW than the three recent gas developments in Victoria. The only technically viable solution for the disposal of the quantities of PW from the Blacktip Field is offshore disposal.




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6.2 BLACKTIP

The proposed method of disposal for Blacktip PW meets industry best practice for PW discharge for the following reasons:

The PW receives extensive treatment prior to discharge (including a gas flotation unit which is beyond usual treatment for PW);

Discharge through a 2km long outfall takes the effluent suitably far offshore and away from any sensitive marine habitats;

The diffuser enhances initial dilution and thereby reduces concentrations in the near field;

Tidal currents are strong in the receiving environment and highly turbulent meaning that concentrations in the plume will not have the opportunity to build up.

Extensive test are planned to ensure that the effluent being discharged is not harmful to the environment in terms of its toxicity or its potential to bioaccumulate in the marine environment.

Monitoring will be undertaken to measure any bioaccumulation in the marine environment.

Should a particularly harmful contaminant be found the technology exists and there will be the opportunity to retrofit equipment as necessary.




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APPENDICES




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A1. ENI HSE POLICY




Page 49 of 50

A2. SEABED CHARACTERISTICS ALONG THE PIPELINE ROUTE




Page 50 of 50

A3. ENVIRONMENTAL PROTECTION LICENCE

The following provides an extract, containing the PW and waste water discharge requirements, from the Environmental Protection Licence issued by the NT Government,. If the PW and waste water sections of this EPL are changed in the future, this PW Management Plan will be revised and resubmitted to DEWHA for approval.


000036_DV_EX.HSE.0381.000_A02 9 July 2009


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A3. ENVIRONMENTAL PROTECTION LICENCE

The following provides an extract, containing the PW and waste water discharge requirements, from the Environmental Protection Licence issued by the NT Government,. If the PW and waste water sections of this EPL are changed in the future, this PW Management Plan will be revised and resubmitted to DEWHA for approval.

ENVIRONMENT PROTECTION LICENCE (Pursuant to section 34 of the Waste Management and Pollution Control Act)

Licence Number: EPL 57

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P.2.1 Flaring quantities shall not exceed the total quantities specified in Table 2 except under emergency conditions or as approved by the Executive Director.

P.2.2 Notwithstanding condition P.2.1, flaring volumes during the first year of normal operation may only be exceeded by up to an average of 20% higher volumes than a Normal Operations or routine operations year (see table 5).

P.3 Dilution of air pollutants

P.3.1 The Licensee shall not dilute emissions with air to comply with this licence.

Monitoring shall consist of an annual certification under condition R.3 that the licensee does not dilute emissions to comply with this licence.

P.4 Produced Formation Water (PFW) investigations

P.4.1 The licensee shall determine, using suitably qualified persons, the chemical

composition of the PFW. This study will provide a breakdown of the parameters listed in Table 5. Method of determination is to be approved by the Executive Director.

Table 5. PFW parameters to be characterised

Analyte pH Electrical Conductivity Total Dissolved Solids Total Suspended Solids Turbidity Total Organic Carbon Total oxidised nitrogen Ammoniacal nitrogen (NH3-N) Total nitrogen Soluble metals (flame AAS) Mercury Speciated Phenols Total Petroleum Hydrocarbons Volatile TPH C6 to C9 Benzene, Toluene, Ethyl benzene and Xylene (BTEX) Polycyclic Aromatic Hydrocarbons (PAHs) Aliphatic/aromatic split Surfactants

P.4.2 The licensee shall determine, using suitably qualified persons, the biodegradation potential of contaminants in the PFW using a method approved by the Executive Director.



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P.4.3 The licensee shall determine, using suitably qualified persons, the bioaccumulation potential of contaminants in the PFW using a method approved by the Executive Director.

P.4.4 The licensee shall conduct toxicity testing of PFW effluent. This testing shall be undertaken:

a) According to the guideline provided in s8.3.6 (Direct Toxicity Assessment: outline and recommendations) of the Australian and New Zealand Guidelines for Fresh and Marine Water Quality 2000 (ANZECC 2000) published by the National Water Quality Management Strategy, or any subsequent review of this document; and

b) Using at least five regionally-relevant species including juvenile prawns.

The primary purpose of the effluent toxicity testing shall be to assist with the derivation of dilution rates, to achieve 99% ecosystem protection1, of effluent in the receiving environment, to be applied at the agreed mixing zone that will not result in environmental harm at or beyond the agreed mixing zone.

P.4.5 The PFW used in the effluent toxicity testing program shall be such that it is sufficiently representative of that which will be discharged to the receiving environment.

P.4.6 Prior to discharge of PFW, the licensee shall conduct a marine baseline monitoring investigation in the areas where the PFW plume is anticipated to be present. The design of the monitoring program is to be approved by Executive Director.

P.4.7 The Licensee shall ensure that the information gained in studies detailed in Conditions P.4.1 – P.4.6 will be used in the PFW dispersion model to determine the potential zone of impact of the discharged PFW.

P.4.8 The Licensee must undertake field validation of the near and far field PFW dispersion modelling predictions as shown in the project’s Produced Water Management Plan (A4.1). The methodology of the field validation is to be approved by Executive Director.

P.4.9 A report detailing results of the investigations as required by P.4.1, P.4.2, P. 4.5, P.4.6, P.4.7 and P.4.8 will be provided to the Executive Director prior to the PFW being discharged. Should the PFW be found to be toxic or show potential for bioaccumulation or persistence in the marine environment, the Licensee will identify in the report and then implement further treatment options for the PFW that will be put in place in the interim between commissioning and when peak volumes occur. Results from P.4.3 will be provided to the Executive Director within three months of PFW becoming available.



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P.4.10 The investigation detailed in P.4.1. – P.4.4 shall be undertaken quarterly in the first year, unless specified otherwise by the executive Director. Frequency of the investigations will be reviewed based on the previous year’s results.

P.4.11 Annual monitoring must include:

(a) Monitoring of the marine environment at the locations utilised during the baseline study detailed in condition P. 4.6.

(b) Interpretation of the results of monitoring required as per part (a) of this condition.

(c) An assessment of the risk to the environment from the PFW discharge

(d) If elevated levels of contaminants, as defined in P.4.1, are identified at the monitoring locations, the licensee must undertake management actions, including: analysis of the PFW discharge to confirm toxicity of the discharge, additional modelling of PFW volumes and plume concentrations, implementation of retro-fit strategies for the PFW treatment equipment to reduce contaminant levels to below that likely to result in contamination.

P.5 Waste water monitoring/discharge points

P.5.1 The waste water discharge points referred to in Table 6 and shown in

Attachment 2 are identified in this licence for the purposes of monitoring and/or the setting of limits for the discharge of waste water from the activity.

Table 6. Wastewater monitoring requirements

Identification Number

Discharge Point

WW01 Produced Formation Water

WW02 Treated wastewater effluent

WW03 Treated Stormwater effluent

P.5.2 The Licensee shall maintain manual sampling points for the waste water

discharges listed in P.5.1. P.5.3 Sampling of waste water shall be undertaken at the frequency shown in Table

7.

P.5.4 The licensee shall ensure that chemical contaminants in discharged wastewater do not exceed the limits shown in Table 7.

P.5.5 The Licensee shall maintain flow meters listed in Table 8 to measure and record volumes of waste water discharges.



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P.5.6 The PFW discharge volume is not to exceed 11,700m3 in the first year of production, unless otherwise approved by the Executive Director.

Table 7. Wastewater monitoring requirements

Licensed Discharge Contaminant Limits Frequency Produced Formation

Water (WW01) Volume (L) pH (5-9) BOD (≤ 20 mg/L) Total Suspended Solids (≤10 mg/L) Total Dissolved Solids (≤250 mg/L) Total Petroleum Hydrocarbons (≤30 mg/L) Total Nitrogen (≤40 mg/L) Total Phosphorous (≤10 mg/L)

Prior to discharge2

Treated Wastewater Effluent (WW02)

Volume (L) pH (5-9) BOD (≤ 20 mg/L) Total Suspended Solids (≤10 mg/L) Total Dissolved Solids (≤250 mg/L) Total Petroleum Hydrocarbons (≤10 mg/L) Total Nitrogen (≤40 mg/L) Total Phosphorous (≤10 mg/L) E.Coli (≤150 MPN/100 ml)

Weekly1

Treated Stormwater Effluent 2 (WW03)

Volume (L) pH (5-9) BOD (≤ 20 mg/L) Total Suspended Solids (≤10 mg/L) Total Dissolved Solids (≤250 mg/L) Total Petroleum Hydrocarbons (≤10 mg/L) Total Nitrogen (≤40 mg/L) Total Phosphorous (≤10 mg/L)

Prior to discharge2

Notes:

1. Discharges are to be sampled weekly for the first year of operations. Based on the performance of the system during this year the frequency of the monitoring will be reviewed for the following years.

2. Discharges are to be sampled at a frequency of once per week for prolonged or continuous discharges, or once per event during short-duration intermittent discharges.

Table 8. Blacktip water flow meters

Discharge ID No. Flow Meter Reference number

PFW WW01 555.1 FIT 041

Treated Stormwater Effluent WW03 560.1 FIT 002

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