Environmental effects of marine structures · A Victorian Government project Environmental effects...

A Victorian Government project

Environmentaleffects of marine

structuresVictorian Desalination Project

Environment Effects Statement Volume 2

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Contents

Table of Contents 1

Table of Contents

Victorian Desalination Project Document Structure ...................................................i Volume 2 Environmental effects of Marine Structures................................................................................ ii

1 Introduction ................................................................................................... 1-1 1.1 Basis of these Project Description...............................................................................................1-1 1.2 Performance Requirements ........................................................................................................1-5

2 Marine Structures Project Description........................................................... 2-1 2.1 Introduction ..............................................................................................................................2-1 2.2 Process for determining the Project Description...........................................................................2-3 2.3 Evolution of the Reference Project for the Marine Structures........................................................2-4

2.3.1 Intake Structure ........................................................................................................2-4 2.3.2 Outlet Structure.........................................................................................................2-5 2.3.3 Tunnels.....................................................................................................................2-6

2.4 Reference Project ......................................................................................................................2-6 2.4.1 Location ....................................................................................................................2-8 2.4.2 Underground structures ........................................................................................... 2-14 2.4.3 Intake head............................................................................................................. 2-15 2.4.4 Outlet head ............................................................................................................. 2-18 2.4.5 Marine growth control .............................................................................................. 2-22 2.4.6 Dimensions and sizes............................................................................................... 2-22

2.5 Construction of the Marine Structures....................................................................................... 2-24 2.5.1 Shafts ..................................................................................................................... 2-24 2.5.2 Tunnels................................................................................................................... 2-24 2.5.3 Pipe jacking.............................................................................................................2-26 2.5.4 Risers ..................................................................................................................... 2-26 2.5.5 Plant site lay-down area........................................................................................... 2-27 2.5.6 Construction exclusion zone ..................................................................................... 2-27 2.5.7 Use of vessels ......................................................................................................... 2-27 2.5.8 Marine yard............................................................................................................. 2-28 2.5.9 Major equipment for construction and special construction needs ............................... 2-28

2.6 Commissioning and operation .................................................................................................. 2-28 2.6.1 Waste generation and disposal ................................................................................. 2-29

2.7 Variations in the EES ............................................................................................................... 2-32 2.7.1 Multiple smaller conduits / pipes on seabed............................................................... 2-32 2.7.2 Passive fine screens on intake head .......................................................................... 2-34 2.7.3 Pipeline diffusers ..................................................................................................... 2-34

2 Table of Contents

2.7.4 Marine Structures locations ...................................................................................... 2-36 2.8 Marine Structure Options ......................................................................................................... 2-36

2.8.1 Indirect intake – seabed filtration ............................................................................. 2-36 2.8.2 Shore to intake/outlet conduits: Tunnels part way and pipes part way – trenched ....... 2-38 2.8.3 Ocean disposal of pre-treatment waste ..................................................................... 2-39

2.9 Concepts outside scope of EES................................................................................................. 2-39

3 Interactions with the marine environment.................................................... 3-1 3.1 Characterisation of the marine environment................................................................................3-1

3.1.1 Intertidal habitats ......................................................................................................3-2 3.1.2 Subtidal habitats........................................................................................................3-3 3.1.3 Pelagic habitat...........................................................................................................3-3

3.2 Impact pathways for the risk and impact assessment ..................................................................3-3 3.3 Risk Assessment........................................................................................................................3-3 3.4 Approach for Impact Assessment ...............................................................................................3-5 3.5 Construction activities and risk assessed medium and above........................................................3-5 3.6 Operation and risks assessed medium and above ........................................................................3-8

4 Marine physical environment......................................................................... 4-1 4.1 Hydrodynamic modelling............................................................................................................4-2

4.1.1 Calibration and validation of models............................................................................4-3 4.2 Landforms and bathymetry ........................................................................................................4-4

4.2.1 Landforms.................................................................................................................4-4 4.2.2 Bathymetry ...............................................................................................................4-5

4.3 Hydrodynamic processes............................................................................................................4-7 4.3.1 Wind climate .............................................................................................................4-7 4.3.2 Wave climate.............................................................................................................4-8 4.3.3 Currents....................................................................................................................4-9

4.4 Sediments............................................................................................................................... 4-14 4.5 Water quality .......................................................................................................................... 4-16

4.5.1 Sampling methods ................................................................................................... 4-16 4.5.2 Sampling results ...................................................................................................... 4-17

4.6 Underwater noise .................................................................................................................... 4-26

5 Marine ecological existing conditions ............................................................ 5-1 5.1 Regional context .......................................................................................................................5-1

5.1.1 The Powlett River ......................................................................................................5-2 5.1.2 Protected areas .........................................................................................................5-2

5.2 Marine ecology..........................................................................................................................5-5

Table of Contents 3

5.2.1 Reef communities ......................................................................................................5-6 5.2.2 Planktonic-pelagic community.....................................................................................5-7

5.3 Benthic habitats ........................................................................................................................5-7 5.3.1 Intertidal habitat........................................................................................................5-7 5.3.2 Intertidal sandy beach community ..............................................................................5-8 5.3.3 Intertidal reef community...........................................................................................5-8 5.3.4 Subtidal habitat .........................................................................................................5-9

5.4 Pelagic habitats ....................................................................................................................... 5-17 5.4.1 Plankton.................................................................................................................. 5-18 5.4.2 Fish ........................................................................................................................ 5-25

5.5 Marine mammals, reptile and birds ........................................................................................... 5-31 5.5.1 Whales and dolphins................................................................................................ 5-31 5.5.2 Seals and sea lions .................................................................................................. 5-35 5.5.3 Marine reptiles......................................................................................................... 5-37 5.5.4 Seabirds.................................................................................................................. 5-38

5.6 Protected marine species ......................................................................................................... 5-43 5.7 Marine pests ........................................................................................................................... 5-48

6 Marine socio-economic................................................................................... 6-1 6.1 Commercial fishing ....................................................................................................................6-1

6.1.1 Abalone ....................................................................................................................6-2 6.1.2 Rock Lobster .............................................................................................................6-2 6.1.3 Finfish (including live wrasse).....................................................................................6-3 6.1.4 Scallops ....................................................................................................................6-3 6.1.5 Trawl fish species ......................................................................................................6-3 6.1.6 Southern Squid Jig Fishery .........................................................................................6-4 6.1.7 King George Whiting ..................................................................................................6-5

6.2 Marine recreational use..............................................................................................................6-5 6.2.1 Game fishing, ocean angling and shore-based fishing ..................................................6-5 6.2.2 Swimming and Surfing ...............................................................................................6-6 6.2.3 Recreational boating and kayaking..............................................................................6-6

6.3 Cultural heritage........................................................................................................................6-6 6.3.1 Aboriginal heritage.....................................................................................................6-6 6.3.2 Maritime heritage ......................................................................................................6-6

7 Construction impact assessment ................................................................... 7-1 7.1 Impact assessment....................................................................................................................7-2

7.1.1 Risks assessed medium or above................................................................................7-2 7.2 Seabed clearing.........................................................................................................................7-4 7.3 Generation of noise and vibration ...............................................................................................7-5

4 Table of Contents

7.4 Use of chemicals and hydrocarbons ............................................................................................7-7 7.5 Production of drilling spoil ..........................................................................................................7-8 7.6 Movement of marine vessels ......................................................................................................7-9

7.6.1 Increase in marine traffic ...........................................................................................7-9 7.6.2 Introduction of pests and disease ...............................................................................7-9

7.7 Use of construction divers........................................................................................................ 7-10 7.8 Construction affecting social Amenity........................................................................................ 7-10 7.9 Exclusion zone ........................................................................................................................ 7-11 7.10 Increased access to Williamsons Beach.....................................................................................7-12

7.10.1 Risks assessed as low .............................................................................................. 7-12 7.11 Performance Requirements during construction......................................................................... 7-16

8 Operations impact assessment ...................................................................... 8-1 8.1 Intake of seawater ....................................................................................................................8-2

8.1.1 Impact assessment – Intake.......................................................................................8-3 8.2 Discharge ............................................................................................................................... 8-22

8.2.1 Ecotoxicity testing.................................................................................................... 8-25 8.2.2 Water Quality .......................................................................................................... 8-27 8.2.3 Hydrodynamic Modelling .......................................................................................... 8-29 8.2.4 Results.................................................................................................................... 8-31 8.2.5 Process for determining the mixing zone ................................................................... 8-39 8.2.6 Impact assessment – Discharge................................................................................ 8-39

8.3 Combined effects of operation of the Marine Structures ............................................................. 8-44 8.4 Other impacts assessed ........................................................................................................... 8-46

8.4.1 Risks assessed as medium or above.......................................................................... 8-46 8.4.2 Risks assessed as low .............................................................................................. 8-47

8.5 Performance Requirements for operation .................................................................................. 8-49

9 Summary of environmental effects................................................................ 9-1 9.1 Assessment methodology...........................................................................................................9-1 9.2 Existing environment .................................................................................................................9-2 9.3 Construction of Marine Structures...............................................................................................9-3 9.4 Operation of Marine Structures...................................................................................................9-6 9.5 Conclusions...............................................................................................................................9-8

Table of Contents 5

Figures

Figure 1-1 Reference Project, Variations and Options for the Marine Structures........................................1-3 Figure 2-1 Process for considering Options and Variations for the Reference Project for the EES ...............2-3 Figure 2-2 Marine Intake system concepts considered ............................................................................2-5 Figure 2-3 Overview of seawater desalination concept............................................................................2-7 Figure 2-4 Indicative location of the Marine Structures ......................................................................... 2-11 Figure 2-5 Marine sensitivity areas ...................................................................................................... 2-13 Figure 2-6 Schematic of underground structures adopted for the Reference Project ............................... 2-14 Figure 2-7 Schematic of seawater intake head ..................................................................................... 2-17 Figure 2-8 Reference Project design for the seawater intake head......................................................... 2-18 Figure 2-9 Schematic of rosette-style outlet diffuser ............................................................................. 2-19 Figure 2-10 Concept design for the Reference Project concentrate outlet ................................................ 2-20 Figure 2-11 Marine Structures concept .................................................................................................. 2-24 Figure 2-12 Typical tunnel-boring machine (TBM) .................................................................................. 2-25 Figure 2-13 Waste streams and their composition .................................................................................. 2-29 Figure 2-14 Multiple smaller pipes Variation schematic ........................................................................... 2-33 Figure 2-15 Tunnels / conduits with pipes on seabed Variation schematic................................................ 2-33 Figure 2-16 Pipeline-style diffuser concept............................................................................................. 2-35 Figure 2-17 Fukuoka seabed infiltration system...................................................................................... 2-37 Figure 2-18 Tunnels and pipe option ..................................................................................................... 2-39 Figure 3-1 Characteristics of the marine environment .............................................................................3-2 Figure 3-2 Conceptualisation of construction activities and risks for the Marine Structures in the Reference

Project ................................................................................................................................3-8 Figure 3-3 Conceptualisation of the operation of the Marine Structures in the Reference Project ............. 3-10 Figure 4-1 Hydrodynamic model inputs and outputs ...............................................................................4-2 Figure 4-2 Bathymetry of the Project area extending into Bass Strait.......................................................4-6 Figure 4-3 Project area bathymetry .......................................................................................................4-6 Figure 4-4 Wind Rose for Bass Strait 1997 to 2007.................................................................................4-8 Figure 4-5 Offshore wave climate at Project area ...................................................................................4-9 Figure 4-6 Peak ebb (left) and flood (right) tidal currents within Bass Strait ........................................... 4-10 Figure 4-7 Typical peak flood (upper) and ebb (lower) tidal currents within northern Bass Strait ............. 4-11 Figure 4-8 Non-tidal current modelling results (September-October 2007) for northern Bass Strait.......... 4-12 Figure 4-9 Results for non-tidal current modelling from September to October 2007 at the Project area .. 4-13 Figure 4-10 Salinity though water column in Project area ....................................................................... 4-18 Figure 4-11 Temperature of water column at Project area ...................................................................... 4-19 Figure 4-12 Dissolved Oxygen (DO) depth profile from sampling site....................................................... 4-20 Figure 4-13 Total nitrogen and total Kjeldahl nitrogen at the Project area from June 2007 to June 2008 ... 4-22 Figure 4-14 Total ammonia nitrogen, nitrate and nitrite and combined total of all, at the Project area from

June 2007 to June 2008 ..................................................................................................... 4-23 Figure 4-15 Phosphorus concentration at the Project area from June 2007 to June 2008.......................... 4-24

6 Table of Contents

Figure 5-1 Marine parks and coastal reserves near the Desalination Plant site..........................................5-3 Figure 5-2 Conceptual model of marine community offshore from Wonthaggi ..........................................5-6 Figure 5-3 Distribution of habitats offshore from the Project area............................................................5-9 Figure 5-4 Reef community changes with water depth.......................................................................... 5-12 Figure 7-1 Noise modelling results for geophysical survey at the intake location.......................................7-7 Figure 8-1 Change in particle visits due to the intake for larval periods of 1 day (upper) and 2 days (lower) ... ...........................................................................................................................................8-9 Figure 8-2 Change in particle visits due to the intake for larval periods of 7 days (upper) and 14 days (lower)

......................................................................................................................................... 8-11 Figure 8-3 Change in particle visits due to the intake for larval periods of 30 days.................................. 8-13 Figure 8-4 Change in particle visits due to the presence of the intake for larval periods of 60 and 120 days....

......................................................................................................................................... 8-14 Figure 8-5 Specialist investigations for discharge impact assessment..................................................... 8-24 Figure 8-6 Salinity versus time exposure for each of the four jets on a single rosette ............................. 8-36

Table of Contents 7

Tables

Table 1-1 Reference Project Variations and Options for the Marine Structures.........................................1-4 Table 2-1 Key elements of the Marine Structures ..................................................................................2-1 Table 2-2 Approximate capacity of Marine Structures ............................................................................2-2 Table 2-3 Summary of key dimensions and sizes for Marine Structures in the Reference Project ............ 2-22 Table 3-1 Risk Assessment Matrix ........................................................................................................3-4 Table 3-2 Summary of construction environmental risks for the Marine Structures assessed as medium and

higher .................................................................................................................................3-6 Table 3-3 Summary of operational environmental risks for the Marine Structures assessed as medium and

above..................................................................................................................................3-9 Table 4-1 Spatial scale of the hydrodynamic models..............................................................................4-3 Table 4-2 Calibration and validation locations and period for hydrodynamic models.................................4-4 Table 4-3 Sediment particle size analysis ............................................................................................ 4-15 Table 4-4 Ion balance for marine water at the Project site................................................................... 4-17 Table 4-5 Existing nutrient water quality parameters ........................................................................... 4-21 Table 4-6 Median metal concentrations at the Project area from June 2007 to June 2008...................... 4-25 Table 4-7 Dominant ambient sound sources and their emission frequencies.......................................... 4-26 Table 5-1 Fish and Cephalopods recorded in surveys of subtidal rocky reefs in the Bunurong Marine National

Park .................................................................................................................................. 5-14 Table 5-2 Planktonic stages of some local marine species .................................................................... 5-20 Table 5-3 Sampling numbers of anchovy and other fish eggs collected in 2007. .................................... 5-24 Table 5-4 Pelagic fish and cephalopods found in mid-water and demersal habitats in Bass Strait and Western

Port................................................................................................................................... 5-26 Table 5-5 Whale and dolphin species known to inhabit the Project area or surrounding Victorian waters 5-31 Table 5-6 Seal species protected under the EPBC Act or known to inhabit Victorian waters.................... 5-36 Table 5-7 Seabirds recorded in the Project area .................................................................................. 5-38 Table 5-8 Protected marine biota listed under the EPBC Act and FFG Act likely to occur in the Project area ...

......................................................................................................................................... 5-44 Table 5-9 FFG Act protected marine invertebrate species..................................................................... 5-46 Table 5-10 Introduced and cryptogenic species at the Project area ........................................................ 5-49 Table 6-1 Shipwrecks lost within 10 kilometres of the Project area .........................................................6-7 Table 7-1 Construction risks assessed as medium or above ...................................................................7-2 Table 7-2 Performance Requirements................................................................................................. 7-18 Table 8-1 Risks from operation of the intake assessed as medium and higher.........................................8-5 Table 8-2 Adopted default trigger values for marine waters in the Project area ..................................... 8-27 Table 8-3 Current parameter values and wave climate for modelling scenarios for the seawater concentrate

plume................................................................................................................................ 8-30 Table 8-4 Estimated composition of the Reference Project Desalination Plant discharge prior to dilution. 8-32 Table 8-5 Mid-field modelling results .................................................................................................. 8-36 Table 8-6 Risks from operation of the outlet assessed as medium or above .......................................... 8-40 Table 8-7 Other risks from operation of the Marine Structures assessed as medium or above ................ 8-46

8 Table of Contents

Table 8-8 Performance Requirements ............................................................................................................ 8-51

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Victorian Desalination Project

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Victorian Desalination Project Document Structure i

Victorian Desalination Project Document Structure

This Victorian Desalination Project Environment Effects Statement comprises a

main report and accompanying Technical Appendices. The main report is divided

into five volumes. Volume 1 defines the Project and summarises the

environmental effects. Volumes 2 to 5 provide detail on the Project’s four

components:

• Marine Structures

• Desalination Plant

• Transfer Pipeline

• Power Supply.

Volume 1 explains the requirement for the Environment Effects Statement, sets

the policy context and describes the Project evolution. It sets out the evaluation

framework adopted to assess:

• the environmental effects of the Project, integrated across all of the Project

components, as required by the Environment Effects Act 1978 (Vic)

• the environmental effects of the Project on matters of national

environmental significance, as required by the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth).

Volume 1 also presents an overview of the environmental impact and risk

assessment contained in Volumes 2 to 5 and the Technical Appendices together

with the Environmental Management Framework to mitigate, manage and

monitor the effects.

Volume 1 Synthesis of

environmental effects

Volume 2 Environmental

effects of Marine Structures


effects of Desalination Plant


effects of Transfer Pipeline


effects of Power Supply

ii Victorian Desalination Project Document Structure

Volumes 2 to 5 describe the Project components and summarise the potential

interactions between the component and the environment during construction

and operations phases. Each volume then presents the environmental effects of

the component. The assessment of these effects is based on specialist reports

provided in the Technical Appendices.

A Summary Brochure has been prepared to provide a concise and clear

summary of the Victorian Desalination Project Environment Effects Statement,

the environment of the region, the potential effects associated with the

construction and operation of the Project, and mitigation measures to manage

or avoid potentially significant effects. The Summary Brochure is based on

information presented in this Environment Effects Statement.

Volume 2 Environmental effects of Marine Structures

This Environment Effects Statement volume describes the Reference Project and

Variations for the Marine Structures. The Options identified for procedural

determination by the Minister for Planning are also presented. This volume

discusses existing marine physical and ecological conditions, the hydrodynamic

modelling used to characterise the environment and the social and economic

activities associated with the marine environment. It also describes modelling

used to predict the effects of construction and operation of the Marine

Structures. This informs the environmental impact and risk assessment.

Mitigation and management strategies are then presented. The Volume 2

chapters are shown in the following table.

Chapter Title Content

1 Introduction Describes the basis of the Project Description

2 Marine Structures Project

Description

Discusses the Reference Project and Options for assessment. Details the Marine

Structures development and operation concept as well as Project requirements

3 Interactions with the

Marine environment

Describes the characteristics of the marine environment around the Marine

Structures

4 Marine physical

environment

Summarises the existing conditions of the marine physical environment based on

specialist investigations, including hydrodynamic modelling

5 Marine ecological existing

conditions

Summarises the existing conditions of the marine ecological environment based on

specialist investigations

Victorian Desalination Project Document Structure iii

Chapter Title Content

6 Marine socio-economic Summarises the existing socio-economic conditions of the marine environment based

on specialist investigations

7 Construction impact

assessment

Describes the construction related impacts and their effect on receptors. Includes

strategies for mitigation and management of impacts and effects

8 Operation impact

assessment

Describes the operation related impacts and their effect on receptors. Includes

strategies for mitigation and management of impacts and effects

9 Summary of effects of

Marine Structures

Summarises the environmental, social and economic effects of the construction and

operation of the Marine Structures

1.0

Intro

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1.0 Introduction

Chapter 1 Introduction 1-1

1 Introduction

1.1 Basis of these Project Description

An overview of the Project, the project delivery process and the environmental

impact and approvals process is provided in Volume 1 Chapter 1. That chapter

explains that the Project would be delivered by a Project Company under

contract to the State under a Public Private Partnership (PPP) structure.

The ultimate Project design would be determined from among designs, bid

competitively by commercial consortia, who would be seeking to provide value

for money and design innovation to the Government for delivery of the Project.

There are a number of forms in which the Project could be delivered by the

Project Company to meet the broad objective of supplying desalinated seawater

to Melbourne, and potentially to regional water authorities. Further detail of this

process and its interaction with the EES is provided in Volume 1 Chapter 1.

The final form of the Project would not be determined until after the completion

of the EES. Accordingly, the EES needs to be flexible so that it does not unduly

impede innovation and reduce the benefits of the PPP procurement.

To meet this challenge, the EES is based on a Project Description that is more

complex than is usual for an EES. This approach is explained more fully in

Volume 1 Chapter 1 and is demonstrated in Volume 1 Chapter 4.











Technical Appendix

Chapter 1 Introduction

1-2 Chapter 1 Introduction

The Project Description and subject matter of this EES is:

• the Performance Requirements

• the Reference Project

• Variations.

The Performance Requirements govern the Project for EES purposes, and are

intended to be the basis for any contract with the Project Company. The

Performance Requirements set the environmental parameters for the Project.

The Reference Project is an integrated response to the Performance

Requirements developed by the State. It is used in this EES to demonstrate the

Project's feasibility and ability to achieve acceptable environmental outcomes.

Variations contemplate other design and management solutions which also meet

the Performance Requirements and are within the scope of this EES assessment.

In addition, the EES identifies Options that may potentially be of interest to the

Project but which have not been considered further for technical or commercial

reasons, or because they did not appear to offer significant advantages over the

Reference Project. While these Options have not been fully assessed in the EES

they are matters upon which comment is invited. Any further process for the

Options will be determined by the Minister for Planning prior to any

endorsement by the State for utilisation in the Project.

The key infrastructure elements of the Reference Project, Variations and Options

for the Marine Structures are shown in Figure 1-1 and Table 1-1 and are

discussed in Chapter 2 of this volume.


Figure 1-1 Reference Project, Variations and Options for the Marine Structures

1-4 Chapter 1 Introduction

Table 1-1 Reference Project Variations and Options for the Marine Structures

Key elements

Reference Project Variation Options

Intake concept

Direct intake in deep water

Intake concept draws into

the plant water from above

the seafloor via an intake

head structure offshore i.e.

outside the wave zone

Indirect – seabed filtration

A sub-surface intake constructed in

deep water that draws water into

the Plant via a filter that is

constructed in the seabed

Marine conduits

Large tunnels and shafts

Two shafts are constructed

onshore (one for each

tunnel) which allow the

tunnel-boring machine to

descend to the required

depth of the tunnels, which

extend from each shaft

Multiple conduits/pipes on seabed

Multiple tunnels or a series of pipes

could be constructed rising to

intersect with the seabed and

through to connect with the intake

and outlets. In addition, pipes

could then be connected and run

along the seabed to connect to

intakes or outlets

Tunnel and then pipes trenched into seabed

Tunnels extend from the plant site

under the dunes, beach, and wave

zone then risers connect the tunnels

to a series of pipes that are

trenched into the seabed out to the

required depth

Intake head

Mushroom structure

Intake structure draws in

seawater horizontally

Intake screening

Grill on intake head

Active screen onshore

Intake mushroom head with

grill size to reduce

entrainment of larger marine

biota.

Passive fine screen at intake head

Passive fine screen on mushroom

Intake head to reduce

entrainment. Requires air

backwashing.

Concentrate outlets

Rosette diffuser

A number of diffuser heads

are connected to tunnel

risers. On each head are a

number of nozzles angled to

avoid the plume reaching the

seafloor. The diffuser heads

are evenly spaced along the

end section of the tunnel

Pipeline diffuser

Connected to a tunnel riser is

either a number of small pipes or a

large pipe that extend outwards

above the seafloor. Each pipeline

has a number of nozzles angled to

avoid the plume reaching the

seafloor


Key elements

Reference Project Variation Options

Marine Structure locations

Offshore on low profile reef

Location offshore on low

profile reef

Alternative locations

Location offshore in alternative

location on low profile reef or on

sand in deeper water

1.2 Performance Requirements

The Performance Requirements (PRs) in their final form are intended to form

the basis of the Government’s requirements for Project performance and will be

translated into contractual obligations.

In assessing the environmental effects of the Project, reliance should ultimately

be placed on the PRs rather than the Reference Project. While a specific finding

on the acceptability of the Reference Project and Variations is sought, the PRs

are the Project outcomes which will apply regardless of the specific solutions

adopted.

The PRs (as ultimately resolved from the outcomes of the environmental

assessment processes) will be used:

• to assess the capacity of a bid project to perform in accordance with the

PRs and the level of that performance

• to inform the contractual requirements for performance by the Project

Company.

The PRs are incorporated into the Environmental Management Framework and

embody the recommendations for environmental management arising from the

environmental impact and risk assessment process.

The relevant PRs for each impact assessment are presented at the end of

Chapters 7 and 8 in this EES Volume, along with commentary about linkages to

the relevant management measures suggested in the technical investigations in

relation to the Project.

2.0

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2.0 Marine structures

project description

Chapter 2 Marine Structures Project Description 2-1

2 Marine Structures Project Description

2.1 Introduction

The Desalination Project would require structures in the ocean and conduits

to deliver seawater to the Desalination Plant and return concentrated saline

and other waste streams (concentrate) to the ocean in an environmentally

acceptable manner. The key infrastructure elements of the Marine Structures

are described in Table 2-1.

Table 2-1 Key elements of the Marine Structures

Elements Description of Reference Project

Seawater intake

Heads The seawater intake would draw in the seawater to be desalinated at the Plant. The intake would

be located offshore and designed to reduce impingement and entrainment of debris and larger

organisms.

Risers Risers would connect the intake heads to the tunnels using steel shafts or fibreglass shafts and a

pre-cast concrete base grouted to the rock surface. Below the rock surface the riser would be

drilled down to the tunnel.

Tunnel The intake tunnel would be located under the seabed and transfer the intake water to the

Desalination Plant under the beach, coastal dunes and reef closer to shore.

Screening Raw seawater would be screened through to remove debris prior to a feedwater pre-treatment

process.











Technical Appendix

Chapter 2 Marine Structures Project Description

2-2 Chapter 2 Marine Structures Project Description

Elements Description of Reference Project

Marine growth control The intake head and tunnel would be intermittently dosed with high levels of chlorine to reduce the

build-up of marine growth. The chlorine would be de-chlorinated before the RO membrane process

because it can damage the RO membranes.

Saline concentrate outlet

Tunnel Desalination produces saline concentrate — a liquid that contains elevated levels (approximately

double) of the dissolved salts that are naturally present in seawater, together with small amounts

of additional process chemicals.

The outlet tunnel would be located under the seabed and transfers the saline concentrate from the

Desalination Plant to the ocean. The tunnel would be bored under the beach and coastal dunes.

Risers Risers connect the tunnels to the diffusers and consist of pre-cast concrete base grouted to the

rock surface. Below the rock surface the riser would be drilled down to the tunnel.

Diffusers The outlet diffusers would be located offshore in deep water and at sufficient distance from the

seawater intake to avoid interference and short-circuiting. The outlet diffuser arrangement would

achieve a required dilution of the concentrate.

The approximate capacity requirements for the Marine Structures to handle

150 GL to 200 GL of potable water each year and to discharge the saline

concentrate created by the reverse osmosis (RO) process, are set out in

Table 2-2.

Table 2-2 Approximate capacity of Marine Structures

Design capacity Indicative volume

150 GL per year 200 GL per year

Seawater Intake 360 GL per year 480 GL per year

Saline Concentrate Outlet 210 GL per year 280 GL per year

Potable Water 150 GL per year 200 GL per year


2.2 Process for determining the Project Description

A wide range of concepts for different aspects of the Project was initially

explored. These concepts were then assessed for technical feasibility for the

particular location, geology, water quality, etc. and relegated to a ‘no further

assessment’ category if thought unlikely to be feasible.

Concepts that survived the feasibility assessment progressed to a further tier of

assessment against Project Objectives to determine a short list of concepts that

were considered both feasible and environmentally and socially acceptable.

From this short list, choices were made of the concepts that demonstrated

practicality, achievability and value for money in the context of consistency

with Project Objectives and ease of integration with other Project components.

This process is shown diagrammatically in Figure 2-1.

Figure 2-1 Process for considering Options and Variations for the Reference Project for the EES


2.3 Evolution of the Reference Project for the Marine Structures

In evaluating the different concepts for the Reference Project Marine Structures,

the following factors were identified:

• take in seawater from the ocean and deliver it to the Desalination Plant in a

way that minimises negative ecological impacts (such as entrainment and

impingement of marine biota) and ensures a supply of sufficient quality and

quantity of seawater

• dispose of concentrate from the RO process in a way that minimises

negative environmental impacts and ensures that the salinity of the

feedwater to the Plant is not affected by the discharged concentrate

• limit the biofouling of infrastructure submerged in the marine environment

to ensure a reliable and consistent supply of seawater to the Plant

• utilise appropriate technologies that maximise performance of the Marine

Structures and freshwater output.

Concepts based on both literature survey and technologies adopted elsewhere in

Australia and internationally were assessed against these criteria.

2.3.1 Intake Structure

Two broad categories of seawater intakes were considered for the Reference

Project:

• direct – open seawater intakes

• indirect – sub-surface intakes.

Within each category several concepts were identified and assessed. These are

summarised in Figure 2-2 and discussed in further detail later in this chapter.


Figure 2-2 Marine Intake system concepts considered

Taking account of Project Objectives and feasibility for a plant of this size and

site hydrogeology, the following were selected for more detailed assessment:

• direct surface water intake (open channel intake)

• direct deep water intake (deep water)

• indirect offshore constructed seabed filtration (seabed infiltration gallery).

An open channel intake was discounted as it does not meet the Project

Objective to protect the coast and beach. Direct deep water intakes were

selected for the Reference Project because they are common and a proven

solution.

2.3.2 Outlet Structure

Two broad categories of concentrate outlet structures were considered for the

Reference Project:

• rosette-style diffusers

• pipeline-style diffusers.


There were a number of factors that affected the dilution potential of diffusers,

including exit velocity, depth of nozzles below surface of water, vertical angle of

nozzles and quantity of nozzles and distance between them. Rosettes were

adopted on the basis of constructability in the local marine environment.

Rosette-style diffusers are also proposed for the Sydney desalination project.

2.3.3 Tunnels

The following concepts for the marine intake and outlet conduits were

considered for the Reference Project:

• two tunnels, one intake and one outlet, from the Desalination Plant under

the coastal reserve (dunes, beach) and under the seafloor with only the

shafts and risers which hold the intake and outlet heads rising through

the seafloor

• multiple smaller tunnels (using horizontal directional drilling, microtunnelling

or other techniques)

• trenched pipe from the Plant through the coastal reserve to the beach and

then a pipe laid on the seafloor

• tunnels from the Plant under the coastal dunes, beach and intertidal area to

a distance past the marine sensitivity area and a pipe laid on the seafloor

• pipes attached to a jetty protruding from the beach.

Concepts that failed to meet the Project Objective of avoiding surface

disturbance of the dunes, beach and intertidal areas were subsequently

excluded. Of the remaining concepts, the two-tunnel configuration was selected

for the Reference Design.

2.4 Reference Project

The Marine Structures for the Reference Project are shown conceptually in

Figure 2-3 below.


Figure 2-3 Overview of seawater desalination concept

Seawater would be transferred to the Plant via an intake structure located

offshore. The intake structure is designed to control the flow velocity of the

water at the intake to reduce entrainment of fish and other marine biota.

The intake heads would be connected to the intake tunnel by a vertical conduit,

referred to as a riser. Water would be transferred via an underground conduit

(tunnel) from the seawater intake to a seawater pump station located on the

Plant site from where it would be pumped to the Desalination Plant.


Concentrate produced as a result of the desalination process would contain

elevated concentrations of the salts naturally found in seawater and trace

amounts of some chemicals added throughout the desalination process. The

concentrate would be discharged from the Plant into the sea via an underground

conduit and then through diffuser structures, which would be designed to

minimise ecological impacts from the concentrate discharge.

2.4.1 Location

Siting for the Marine Structures had regard to the risk of entraining marine

organisms in the seawater intake and the need to disperse the concentrate from

the outlet points to avoid impacts of high salinity on marine flora and fauna.

The marine environment adjacent to the Plant site largely determined the

location. Coastal hydrodynamics, seawater quality, marine ecology, bathymetry,

seabed type and other local marine conditions influenced the selection of an

appropriate location for the Marine Structures.

Determining depth

Determining an appropriate depth for the Marine Structures took into

consideration the following:

Feed water quality – water quality is generally better in deeper water

and further offshore.

Sand entrainment (intake) – There is risk of sand and sediment ingress

if an open water (direct) intake was located too close to the seafloor. The

amplitude of sand waves (on the seabed) and their long-term movement

would be influencing factors. Depths of greater than 15 metres and heights

of four metres above the seafloor appear to minimise the amount of sand

entrainment. As a best practice measure, sand entrainment was minimised

for several reasons:

- to avoid sand depletion. The beach at Wonthaggi has a relatively thin

layer of sand overlying rock. Even the sandy seabed locations are

thought to comprise only a relatively thin layer of sand

- to minimise pre-treatment waste (i.e. sand and sediment collected on

the pre-treatment filters)


- to minimise volumes of sand depositing within the intake, seawater

pipeline and plant structures. Accumulation of sand would require an

engineering/maintenance solution to collect and periodically remove

settled material

Proximity to sea surface – Marine Structures positioned deep enough to

prevent entrainment of air and impact on sea vessels

Constructability – Areas close to the coastline are problematic for

construction due to the high ocean swell, breaking waves and strong

currents. Pressure increases with water depth and would create less

favourable working conditions below approximately 20 metres including

heightened risk to construction and maintenance staff, and increased

complexity (time and cost) to ensure safe working procedures.

Intake depth also influences the water quality. Locations in deeper water are

likely to provide more consistent and higher water quality.

Based on the above considerations in the Reference Project, a depth of around

20 metres for both the intake and outlet was considered viable and to provide a

suitable location.

Selecting an appropriate seabed type

In the Reference Project, the selection of the location for the Marine Structures

considered the types of seabed that exist in the area. Based on marine ecology

investigations, efforts were made to avoid areas of the seabed that have high

relief, as these areas usually support a greater diversity of species due to

habitat complexity. Hence, low profile reef was favoured over high profile reef

for ecological reasons. From an ecological perspective (as advised by CEE 2008,

Technical Appendix 31), the preferable marine environments for locating the

intakes and outlets (from highest to least preference) would be:

• mobile sand or mobile gravel

• sand

• scoured reef and rubble

• lower relief reefs

• extensive, high relief or complex reefs.


Separation distance and direction

The positioning of the intake and outlet structures with respect to one another

considered the risk of short-circuiting (i.e. intake of concentrate from the

outlet). Short circuiting would raise the salinity of the water entering the Plant

and reduce efficiency of the desalination process. Therefore, in areas where

currents exist, it is preferable to locate the intake upstream of the outlet.

Sufficient separation distance was also required to ensure no short-circuiting

during unfavourable current conditions. Modelling work concluded that at least

500 metres separation would be required. The indicative location of the Marine

Structures for the Reference Project is shown in Figure 2-4.


Figure 2-4 Indicative location of the Marine Structures


Identification of marine sensitivity areas

All of the above factors have been taken into consideration during the

identification of high sensitivity areas. These sensitivity areas for construction

are illustrated in Figure 2-5 and were derived from the specialist marine studies

(see CEE 2008, Technical Appendix 31). The commitment to avoid construction

in these sensitivity areas is established in the PRs.


Figure 2-5 Marine sensitivity areas


2.4.2 Underground structures

The underground structures for the intake and outlet adopted for the Reference

Project include:

• onshore shafts

• launch and back-shunt chambers

• intake and outlet tunnels

• stub connection tunnels that link the risers to the tunnel.

These are shown schematically in Figure 2-6 below.

Figure 2-6 Schematic of underground structures adopted for the Reference Project


Onshore shafts

These shafts are land elements that would link the Desalination Plant to the

tunnels. The intake shaft would be located near the seawater pumping station.

The shafts would be sunk to a depth below ground at the Plant site

(approximately 65 to 70 metres) so that the tunnels, as they extend seawards,

would slope gradually upwards but with sufficient clearance below the seafloor

to remain in the rock strata.

Launch and backshunt chambers

In the Reference Project, launch and backshunt chambers would be necessary

for assembly and launching of the tunnel-boring machine (TBM). The chambers

would be constructed from the base of the onshore shafts.

Intake and outlet tunnels

The seawater intake and concentrate outlet tunnels would extend horizontally

underneath the coastal reserve and seabed to a distance offshore. The

segmentally lined tunnels would be sloped to enable pumps to drain the shaft.

Dewatering would be necessary to allow access and maintenance, if the need

arises. Both intake and outlet tunnels would be designed to allow periodic

inspection and maintenance. Tunnels would be large enough to accommodate

the ultimate design capacity for the Desalination Plant (200 GL per year).

Stub tunnels

The stub tunnels would link the main tunnel to the risers for seawater intake

and outlet. The length of the stub tunnels would vary depending on the ‘as built’

positions of the riser caissons and the main tunnel.

2.4.3 Intake head

In designing a solution for intake systems, consideration was given to limit

entrainment of marine biota to reduce potential ecological impacts. Open water

intake systems are a proven technology where large volumes of water

are required. The Reference Project has considered the following

engineering controls:


Having the intake water stream horizontal to the seabed so that fish can

sense the water current. Fish are sensitive to horizontal but not vertical

currents and altering the direction of the current has been shown to

significantly reduce the entrainment of fish (CEE 2008, Technical

Appendix 31).

Control of maximum water velocity at the intake to reduce potential

entrainment and impingement of marine biota and debris.

Positioning the intake as far above the bottom as practical to avoid possible

seabed boundary aggregations of biota, but in the bottom third of the water

column. Locating the intake at this level would minimise intake of fish eggs,

larvae, zooplankton in the top part of the water column and minimise intake

of benthic zooplankton and small benthic fish species as well as drifting kelp

and seaweed (although unlikely to be avoidable at all times).

Screening at the intake point to prevent entry of larger marine organisms

and debris. Screening must not create fouling of the intake point, as this

would affect the reliability of the supply. Allowance for control of marine

growth was factored into the design of the intake system, so that the

reliability and quality of feedwater supply is not compromised. Fine screens

at the intake are considered a Variation, which might be adopted to further

reduce the intake of planktonic larvae, zooplankton and small fish species.

These are subject to practical considerations such as biological fouling

growth and the need and ability to regularly clean or replace the screens by

divers or through remote methods.

Chemical dosing to prevent undesirable marine growth in the intake

structure and to minimise the potential for chemicals to escape into the

ocean would be minimised. Intermittent chlorination is typically used to

control marine growth in seawater intake conduits, screens, pump station,

and rising mains. The feedwater is de-chlorinated before the RO process

because it can damage the membranes.

In the Reference Project, the intake head structures were designed to begin in

water with a depth of over 15 metres in order to avoid sediment entrainment,

air entrainment and risks to navigation.


The Reference Project intake has been designed with a mushroom-shaped head

and with a large cross-sectional flow area at the point of entry, which would

narrow as the water progresses towards the riser to the intake tunnel. The

effect of this is to make the flow at the intake entrance relatively slow, reducing

the tendency for mobile organisms to become drawn into the intake stream and

enabling free-swimming marine animals to swim away from the intake stream.

The head would be screened to further reduce entrainment of marine biota. A

specific grill spacing (100 millimetres horizontal by 100 millimetres vertical or 50

millimetres horizontal by a dimension larger than 100 millimetres should the grill

be rectangular) has been adopted in accordance with the Performance

Requirements. Once past the bar grill, the water flow would accelerate down the

narrower riser into the intake tunnel. A schematic of the seawater intake head is

shown in Figure 2-7. The Reference Project design of the seawater intake head

is shown in Figure 2-8.

Figure 2-7 Schematic of seawater intake head


Figure 2-8 Reference Project design for the seawater intake head

2.4.4 Outlet head

Discharge of the concentrate is made via offshore marine structures.

These offshore structures are engineered to obtain a required dilution of the

seawater concentrate. In addition to the outlet diffuser’s design, the depth at

the point of discharge is a contributing factor in achieving the target dilution

The Reference Project adopted a rosette-style outlet that includes several

rosettes with a small number of nozzles attached to each. A typical rosette-style

outlet structure is shown in Figure 2-9. The concept design for the Reference

Project is shown in Figure 2-10.


Figure 2-9 Schematic of rosette-style outlet diffuser


Figure 2-10 Concept design for the Reference Project concentrate outlet

The concentrate would discharge at a velocity driven by the gravity feed from

the Desalination Plant. Higher nozzle velocities produce more effective dilution,

but there are limitations to ensure the plume is not visible from the surface. If

the Plant is not operating at full capacity, a seawater makeup system could be

used to ‘top-up’ the discharge flow volume to maintain the exit velocity required

to achieve adequate dilution. Alternatively, diffuser nozzles can be closed off by

divers although their access is limited to infrequent, calm weather.


Some details of how dilution would be achieved despite variable outflow

rates include:

• maintaining concentrate velocity at the nozzles (velocity is dependent on

the flow and total cross-sectional area of the nozzles)

• use of a seawater pump station to provide ‘make-up flow’ (seawater) to the

outlet, maintaining the flow out of the nozzles when the Plant operates at a

lower rate

• divers could close off some nozzles instead of pumping the ‘make-up flow’

in the event of any ‘long term’ Plant downtime.

Similar to the seawater intake heads, the outlet diffusers would be in water

deep enough to allow dispersion of the concentrate plume in the water column

and to prevent wave damage and avoid risks to navigation.

The dilution achieved by the diffuser design coupled with the location

of the concentrate outlet away from the seawater intake would ensure that

the feedwater to the Plant is not significantly impacted by the discharge

of concentrate.

A pipeline diffuser is a different way of arranging nozzles along a pipe instead of

a rosette and this is considered a Variation to the Reference Project (discussed

in section 2.7.3).


2.4.5 Marine growth control

The concentrate from the outlet structure would typically be concentrated to

6 to 70 practical salinity units (psu) (as compared to an approximate seawater

salinity concentration of 36 psu). Therefore, biofouling is unlikely to be a

problem in the outlet structure. However, the intake structure — which is dark,

relatively free of predators and has a constant flow of seawater — is an ideal

environment for the growth of various attaching organisms such as bacteria,

bryozoans, sponges, mussels and barnacles. The build-up of this growth, or

biofouling, tends to increase the roughness and gradually reduce the diameter

of the pipe, restricting the flow of water and increasing the energy required to

pump it. The Reference Project includes intermittent dosing of the intake

tunnels and risers with chlorine in liquid form (sodium hypochlorite) to minimise

marine growth from the primary bacterial layer so as to prevent the formation of

secondary and tertiary layers of biofouling. This process is used on most

seawater intake systems. The intake water would be de-chlorinated before it is

fed through the RO process so that it does not damage the RO membranes.

This process means no free chlorine is present in the RO reject stream.

2.4.6 Dimensions and sizes

The following table (Table 2-3) sets out the dimensions and sizes for the key

components of the Marine Structures in the Reference Project. The values

provided are consistent with the ultimate Project capacity of 200 GL per year.

Table 2-3 Summary of key dimensions and sizes for Marine Structures in the Reference Project

Marine Structure Key dimensions and sizes for 200 GL/year

Intake/outlet tunnels Design life – 100 years

Intake tunnel diameter – 4 m

Outlet tunnel diameter – 3.2 m

Intake tunnel length – approx. 1.25 km

Outlet tunnel length – approx. 1.5 km

Distance between tunnels – varies, but is approx 500 m at the

sea ends

Flow velocity in tunnels – approx 1.5 m/s


Marine Structure Key dimensions and sizes for 200 GL/year

Intake/outlet shafts Design life – 100 years

Design wave ARI – 1 in 2 000 years

Diameter – 10 m

Depth of shafts below ground level – 65 m to 70 m

Intake/outlet risers Intake diameter – approx. 1.6 m internal

Outlet diameter – approx. 1.1 m

Chlorination of intake – 1 hour per day

Chlorination dose – 10 mg/L

Intake heads Design life – 100 years for the main structure (less for some

items)

Design wave ARI – 1 in 2 000 years

Number of heads – 4

Diameter of heads – 6 m

Top height of heads above seafloor – approx. 8 m

Base height of heads above seafloor– 4 to 5 m

Top distance below sea surface – approximately 20 m

Seawater depth – >15 m

Flow velocity at entrance grill – 0.1 to 0.15 m/s

Bar grill spacing 100 mm horizontal by 100 mm vertical or 50

mm horizontal spacing of vertical bars

Outlet diffusers Design life – 100 years for the main structure (less for some

items)

Flow velocity from diffuser nozzles – 6-7 m/s for normal

operation conditions

Rate of discharge – 10.5 m3/s

Seawater depth – > 10 m

Diffuser height above seafloor – 2 m

Rosette-style diffuser Number of rosettes – 6

Number of nozzles – 4 per rosette


2.5 Construction of the Marine Structures

A conceptual schematic of the marine structures is presented in Figure 2-11.

Figure 2-11 Marine Structures concept

Intake Head

Riser

Two Shafts

onshore for construction

Tunnel

Outlet Diffuser

Tunnel

2.5.1 Shafts

In the Reference Project, shafts at the Plant site would be sunk to a depth

below sea level by excavation, rock hammering, drilling and blasting, depending

on the ground conditions. These shafts would have a permanent reinforced

concrete lining and would be secured with rock bolts where appropriate.

2.5.2 Tunnels

A tunnel-boring machine (TBM) would be driven from the bottom of the shaft

along the predetermined horizontal path for the intake and outlet structures

below the coastal strip, beach and seafloor. It is anticipated that two TBMs

would be used on this Project, one for each tunnel. The type of TBM to be used

would depend on the expected ground conditions. A typical TBM of the type and

diameter that may be used is shown in Figure 2-12.


Figure 2-12 Typical tunnel-boring machine (TBM)

Source: Herrenknecht

Prior to launch, the TBMs would be assembled at the base of each shaft in an

assemblage chamber (the launch and backshunt chambers described above).

It is expected that these chambers would be excavated using either a

roadheader machine or by drill and blast techniques depending on the

geological conditions. Extensive cover grouting may be required outside these

chambers to minimise the quantity of groundwater entering the excavation.

Where there are difficult ground conditions consisting of silt or mud, the ground

may be frozen or injected with grout prior to tunnelling. Bentonite may be used

as a drilling fluid to lubricate and cool the cutting head of the TBM.

The excavated tunnel diameter for the main tunnels would be slightly larger

than the outside diameter of the concrete segment ring that would form the

tunnel. On this Project, where hard rock conditions are anticipated, it is

expected to be possible to grout this annular gap through the tunnel segments

for stability, following the advance of the TBM. This would speed up tunnel

excavation and lining cycle times.

TBM dismantling would occur in an additional segment to the extended tunnel.

The external TBM shield would be left in place and the additional tunnel

segment and shield would then be back-filled with concrete.


Marine spoil volumes as well as broad management options are presented in

Volume 1 Chapter 7.

2.5.3 Pipe jacking

Pipe-jacking, a construction method where sections of pipe are pushed into the

tunnel for self lining as the TBMs are excavating the tunnel, could also be used

for tunnelling. This is another way of constructing a tunnel with a liner which

might be considered by the by the Project Company. The amounts of spoil and

construction impacts are considered similar to be segmentally lined tunnels.

2.5.4 Risers

In the Reference Project it is assumed that a self-elevating platform (SEP or

‘jack-up barge’) would be employed during the construction phase to drill the

intake and outlet risers adjacent to the tunnel alignments.

Riser holes would need to be drilled through the grout base and into the rock, to

finish deeper than the tunnel invert. The overdrill amount is required to enable

grouting of the rock mass prior to commencement of the stub tunnels that

connect the risers to their respective tunnels. The risers are sealed to the ocean

floor and the connection between the riser and the tunnel can be excavated and

lined from the tunnel side. Clearance between the rock diameter and lining

would be provided to allow for chlorine dosing tubes.

It is expected that spoil from excavation of the risers would be collected on the

drill barge and later taken to land for disposal if a suitable marine spoil disposal

site cannot be identified. Smaller diameter rock drilling spoil (e.g. from

temporary rock bolts) would not be collected. It is not expected that the marine

disposal of this spoil would generate significant turbidity during construction.

A number of flat areas about 12 metres in diameter would be required

surrounding each of the risers for the drilling operation, support of heavy

starting ring assembly, and drill and grouting of piles.


2.5.5 Plant site lay-down area

The lay down areas for tunnel construction are included in the construction area

estimates for the Plant component of the Project in Volume 3.

2.5.6 Construction exclusion zone

A temporary construction exclusion zone in the order of two kilometres by two

kilometres would be required to ensure public health and safety.

2.5.7 Use of vessels

Vessels that may be required for construction of the Marine Structures are

anticipated to include:

• SEPs, most likely with accommodation for the small number of resident

crew, helipad etc. and the capability to remain at sea for several months

• large ocean going tugboats for the SEP

• offshore supply vessels to provide supplies and fuel to the platforms

• vessels to take the various project staff and workers on/off the platform

when weather conditions permit

• barges and small tugboats/workboats to lay anchors for the SEP

• support vessels for divers during connection of risers to seawater intake

heads and concentrate outlet diffusers.

Some of these craft would arrive from international or interstate locations and

would need to undergo appropriate quarantine procedures before operating in

Victorian waters.


2.5.8 Marine yard

It is expected that there would need to be an area near an existing wharf for

construction of the marine elements of the Project. This is often known as the

‘marine yard’. This would potentially include facilities for managing drilling

equipment, SEPs, concrete structures and prefabrication of intake and outlet

structures.

2.5.9 Major equipment for construction and special construction needs

The TBM machines require substantial amounts of electrical power, which can

come from the grid or on-site diesel generation. Power supply requirements for

construction are discussed in Volume 5.

2.6 Commissioning and operation

The intake and outlet structures are expected to be commissioned initially by

bypassing water directly from one tunnel to the other without running water

through the Plant. Water would then be gradually diverted to the Plant to allow

slow start up and commissioning of the Plant.

The intake and outlet are designed to operate at a constant rate 24 hours a day.

If the annual production of the Desalination Plant varied from time to time, this

could be accommodated by bypassing some intake flow to the outlet to maintain

diffuser velocities over short periods, or by shutting off or opening more

diffusers for longer periods.

A small operations exclusion zone would be required to prevent interactions

between marine-based activities (e.g. boating) and the Marine Structures. The

size of this exclusion zone would be defined in order to ensure nautical safety,

diver safety and to protect intake water quality, while also taking account of the

benefits to public access to these waters.


2.6.1 Waste generation and disposal

The intake water would contain marine material, which would be removed in the

onshore screens. These screens would be periodically cleaned to remove course

particulate. Seawater must then be pre-treated to remove suspended particles

and dissolved organic molecules from seawater, and direct these into the waste

stream. In the Reference Project the washwater used would be seawater and

therefore this waste stream would be salty and contain both particulate

contaminants such as sediment and micro-organisms, as well as dissolved

metals (from seawater and added chemicals) and organic compounds. This is

shown conceptually in Figure 2-13.

Figure 2-13 Waste streams and their composition

Source: GHD

Screenings

‘Screenings’ is the collective term for the sediment, debris and marine biota that

would accumulate on the onshore intake screens. Onshore storage would be

required to temporarily store skips with screenings while waiting for a truck to

remove them from site to landfill.


Pre-treatment waste

The pre-treatment filters would be periodically cleaned to remove the filtered

finer particulates and maintain effective and efficient operation. These solids

would include the naturally occurring suspended matter in the seawater and

flocculated material from the addition of the coagulant. In the Reference

Project, this backwash wastewater would be dewatered on site to produce a

sludge which would be disposed to landfill.

The solid waste produced during the pre-treatment process would be taken

to landfill. The pre-treated seawater would then proceed through the RO

membrane to produce the desalinated water. The saline concentrate, which is

the by-product of the process, would be discharged to ocean. The supernatant,

the cleaner water taken from the top of the pre-treatment backwash clarifier,

would be returned to the head of the plant, where practicable. During the

commissioning (or recommissioning) process or a rare event such as upset

conditions, a portion of the supernatant could be blended into the concentrate

stream in a controlled manner and discharged to the ocean. This scenario has

been assessed in the ecotoxicity and water quality assessments (discussed in

Chapter 8).

RO concentrate

In the Reference Project, the RO concentrate is proposed to be discharged to

ocean. The RO concentrate would contain seawater with high concentrations of

salt and some process chemicals. These chemicals would include the following:

Antiscalants

Antiscalants would typically be used to protect and maintain membrane

performance. They would assist in preventing precipitation of dissolved

constituents onto the concentrate side of the membranes. Small volumes of

antiscalants would be added to the seawater feed stream before processing

through the RO membrane. The antiscalants would be rejected by the

membranes and therefore become constituents of the seawater concentrate

stream with the other dissolved constituents removed from the seawater that

would then be discharged to the ocean.


Chemical cleaning of RO membranes

Over time, the RO membranes’ permeability would be reduced due to fouling

and scaling. Fouling and scaling would impair the system performance by

reducing the flux of water possible through the membranes at a given pressure,

and would require higher pressures for the same water production and hence

greater energy use.

The required cleaning frequency for RO membranes can vary from once every

two years to four cleaning cycles per year. This frequency would be dependent

on the seawater quality, the efficiency of the pre-treatment process and the

antiscalants employed.

Possible cleaning and preservation chemicals include:

• caustic soda

• sodium bisulfite

• hydrochloric acid

• detergents

• disinfectants

• citric acid

• ammonia.

Cleaning occurs intermittently and these chemicals would not be used all at the

same time. The amount and type of cleaning chemical required would vary

depending on the degree of membrane fouling and the nature of the fouling.

At the completion of each clean, the wastewater would be sent to a

neutralisation tank. The quantity of cleaning wastewater would depend on

cleaning frequency. Once neutralised, the cleaning wastewater would be

pumped under controlled conditions for disposal via the concentrate outfall,

which is the approach adopted for the Perth and Sydney desalination plants.


2.7 Variations in the EES

Four Variations are included within EES are:

• multiple smaller conduits in place of large marine conduits with potential for

pipes placed on the seabed

• passive fine screens at intake head

• pipeline diffuser

• alternate locations for the Marine Structures.

2.7.1 Multiple smaller conduits / pipes on seabed

A Variation for the Marine Structures would be to construct smaller multiple

tunnels to extend from the Plant to the structures. A range of different

construction techniques such as horizontal directional drilling, micro-tunnelling,

pipe-jacking and other might be used. These techniques all lead to the same

result of a smaller diameter hole lined with some form of pipe.

The conduits could extend either to the points where the inlet and outlets would

be located, or, alternatively, could connect to pipes running above the seafloor

outside of the marine sensitivity area. These pipes could then extend to the

location of the inlets and outlets. These Variations are presented schematically

in Figure 2-14 and Figure 2-15.


Figure 2-14 Multiple smaller pipes Variation schematic

Vegetated Dunes

Beach

Multiple smaller tunnels under dunes and high

profile reef

Small "Rosette" Style Diffusers

Marine Sensitivity Area

Plant to Shore SectionShore to Intake/Outlet Section

Figure 2-15 Tunnels / conduits with pipes on seabed Variation schematic

Beach

Pipe(s) along seafloor anchored at regular spacings

Vegetated Dunes


Tunnel under dunes and high

profile reef


Outlet or Intake


2.7.2 Passive fine screens on intake head

A Variation to the intake system is to construct a passive screening system at

the intake head. In this Variation, a fine screen with screen openings of

approximately 0.5 to 10 millimetres would be fitted to the intake structure to

reduce entrainment in the intake stream. An offshore passive screen at the

intake head would filter a higher quantity of marine biota out of feed water and

would produce lower level of waste onshore. It would require air backwashing

to dislodge marine biota and particles caught in the mesh. In order to

accommodate the require intake flow, it is likely that multiple passive screen

units would be required if this Variation were adopted.

Fine inlet screens have practical challenges given the marine environment and

the scale of the Project. Air backwashing might pose a navigation hazard and

the requirements for regular maintenance might prove to be impractical. Given

the lack of proven experience of this scale in marine environments like the

Project area for passive fine screens, the Reference Project adopted offshore

grills and fine onshore screens.

2.7.3 Pipeline diffusers

A Variation considered for the concentrate outlet structure is a pipeline-style

diffuser. This diffuser may involve either a series of smaller and/or shorter

pipelines or one large pipeline and could be orientated either parallel or

perpendicular to the beach at a site further offshore. These pipelines would

contain nozzles, usually at an even spacing. There are several aspects of

pipeline diffuser design including:

• orientation of the pipelines, e.g. longshore or offshore

• number of pipelines

• number of nozzles

• horizontal angle of the nozzles, i.e. neighbouring nozzles usually ‘point’ in

opposite directions.


Pipeline diffusers are constructed using similar techniques to rosette-style

diffusers and provide similar performance. All pipes would require permanent

weighting and anchoring which could be achieved by a number of approaches

including concrete collars, anchor ties or other methods.

A suitable pipeline-style diffuser based on the above design elements may

be selected and is considered a viable Variation to the Reference Project.

The concept is shown in Figure 2-16.

Figure 2-16 Pipeline-style diffuser concept

Pipeline Style Diffusers above

seabed

Multiple risers Single or multiple

tunnels



Vegetated Dunes

This kind of linear arrangement of nozzles could also be engineered with a

number of smaller conduits connected to individual heads. Regardless of the

construction approach, these methods all use the same functional design of

high-velocity nozzles.


2.7.4 Marine Structures locations

Subject to technical feasibility and compliance with the Performance

Requirements relating to environmental impacts, alternative locations and

alignments of the Marine Structures to those adopted in the Reference Project

(including their extension further out to sea) are possible and acceptable.

The Marine Structures could be placed at locations other than the Reference

Project location, on the low profile reef or sand, such that their impacts during

construction and operation fall outside the identified marine sensitivity areas

(shown in Figure 2-5). The Performance Requirements contain a requirement for

the Project to obtain approval from the EPA for a mixing zone for the discharge

of the saline concentrate that avoids the marine sensitivity areas, but could

otherwise be located anywhere else offshore.

2.8 Marine Structure Options

2.8.1 Indirect intake – seabed filtration

This Option involves a sub-surface infiltration gallery intake system consisting

of a submerged slow sand media filter constructed on the bottom of the ocean,

which is connected with pipelines or tunnels to a series of intake wells located

on the shore.

Infiltration intakes would be constructed by excavating the seafloor to avoid low

depth to install intake piping of wells and perforated pipes buried at the bottom

of the ocean floor. Filter sand would then be filled in above. During operation

approximately 25 millimetres of sand would be removed from the surface of the

filter bed every six to 12 months for a period of several years, after which it

would be replaced with new sand to its original depth.

Seawater would be filtered through the engineered sands and gravel, which

minimises the potential for entrapment and impingement of marine biota and

reduces the need for chemical dosing.

A subsurface infiltration gallery intake system is used at the 50 ML/day

desalination plant at Fukuoka, Japan. The filter has an area of approximately

2.9 hectares and is 11.5 metres deep. A conceptual image of the Fukuoka plant

is presented in Figure 2-17.


Figure 2-17 Fukuoka seabed infiltration system

Source: Fukuoka District Waterworks Agency, 2008

Note: this cross-section from the Fukuoka seabed infiltration system appears to show

impacts on the beach. This is not permitted for the Victorian Desalination Project.

Key considerations for the gallery intakes used in the seabed filtration

system include:

Infiltration galleries are typically considered when conventional wells cannot

be used due to unfavourable hydrogeological conditions (i.e. low

permeability or small beach thickness).

Seawater is filtered through an engineered media (sand and gravel) as it is

being collected thereby reducing pre-treatment requirements.

Construction requires excavation of large areas of the seabed.

Viability of engineered sub-surface offshore infiltration intakes is uncertain,

as they have only been used in one instance for a large-scale plant

(Fukuoka, Japan – 50 ML/d plant capacity).


Viability for use for large-scale plants has not been proven and may be

unlikely due to the large area of constructed filter bed and associated spoil

volumes. This would need to be located in an identified low impact marine

area such as existing sand beds. This would increase project costs.

Sub-surface intakes may cause entrainment of small marine life (such as

plankton and larvae) inside the sand substrate below the bottom of the

ocean floor. Unless there is a natural mechanism, such as wave action, to

scour and frequently flush the bottom ocean floor substrate and release

trapped marine biota, this marine biota would be lost from local

ecosystems.

Construction may need to be in deep water to avoid adverse effects from

wave action on the engineered sands and gravels. This would increase

costs.

2.8.2 Shore to intake/outlet conduits: Tunnels part way and pipes part way – trenched

An Option identified for the design of the conduits from the shore to the

intake/outlet structure are tunnels part of the distance followed by pipes

trenched into the seabed (beyond the marine sensitivity area).

The Option envisages tunnelling the intake and outlet pipes from the

Desalination Plant to beyond the high relief reef/coastal reserve and then a pipe

would be trenched to the seabed surface on the low reef/outside coastal

reserve. This is shown schematically in Figure 2-18.

The surface pipe could be laid in a trench constructed along the seafloor.

The trench would need to be constructed prior to installation of the pipe.

As geotechnical information suggests that the seabed may be unsuitable for

dredging, trenching might require drill and blast construction methods or the

use of an excavator from a temporary jetty deck or other structure. This would

only be possible up to certain water depths.

It is likely this would involve the pipe being either dragged or floated into place

and then backfilled with rock or other similar material. While construction of a

trench would cause significant short-term impact to the existing seabed,

maintenance of the flat seabed profile reduces the risk of interference with

coastal processes and rock backfilling may provide colonising opportunities for

reef habitat.


Figure 2-18 Tunnels and pipe option

Vegetated Dunes

Beach

Pipe(s) trenched into seafloor and covered with protective

material

Plant to Shore SectionShore to Intake / Outlet Section

Tunnels under dunes and high

profile reef

batter slopebedding

protective rock amour

pipeseabed

Example of Trenched Pipe Cross Section


2.8.3 Ocean disposal of pre-treatment waste

In this Option, the backwash from pre-treatment produced during this process

would be blended and discharged in the ocean with the saline concentrate.

This would be done in a controlled manner. The backwash contains particulate

material drawn from the ocean together with some water treatment chemicals.

The advantage of this Option is that it reduces the energy use, greenhouse gas

emissions and other impacts of going to landfill. However, further research is

required to understand the risks to the marine environment.

2.9 Concepts outside scope of EES

The concepts that did not warrant assessment in the EES are set out below.


Open channel conduit

Designs for the intake-outlet conduits that involve surface disturbance of the

beach and dune system have been excluded since they do not meet Project

Objectives and Performance Requirements.

Above sea level conduits

Designs for the intake-outlet conduits that involve above-sea level conduits

such as surface pipes on the beach or pipes affixed to jetty structures have

been excluded as they do not meet Project Objectives and Performance

Requirements to preserve coastal integrity.

Vertical intake stream

Intake heads such as ‘pipe intakes’, which create vertical intake streams, have

been excluded from the scope of the EES on the basis that vertical intake

streams do not meet the Performance Requirement of minimising entrainment.

Disposal of saline concentrate to land

Land-based disposal of saline concentrate is not considered a viable Project

Option due to the large volumes of saline concentrate, the need for dewatering

and the comparative ease and availability of ocean disposal. Evaporation of the

seawater concentrate is not technically feasible as there is insufficient

evaporation in the Wonthaggi region. Solar ponds also would have an extensive

footprint, which make this an unfeasible alternative. The use of mechanical

evaporation has high-energy requirements, which render this an uneconomic

method of disposal. Disposal to aquaculture and livestock requires large

amounts of freshwater for dilution and was therefore also considered to be

unfeasible.

Compared with the potential effects of salinity on landfill and associated

management issues, the saline concentrate is rapidly dispersed into the ocean

and diluted, with no continuing effect on the marine environment. Therefore,

land-based disposal has not been assessed for the purposes of this EES.

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3.0 Interactions withthe marine environment

Chapter 3 Interactions with the marine environment 3-1

3 Interactions with the marine environment

This chapter characterises the physical and ecological features of the marine

environment in the Project area and describes how construction and operation

of the Marine Structures may interact with these features through a variety of

causal pathways. The chapter explains how the risk assessment and impact

assessment methodologies for the EES are based on analysis of these pathways.

3.1 Characterisation of the marine environment

There are several distinct marine habitat types located along Bass Coast in the

vicinity of the Project:

• intertidal habitats, including sandy beaches and rock platforms

• subtidal benthic habitats

• pelagic (open ocean) habitat.

These marine habitats are shown conceptually in Figure 3-1. Sandy beaches

above the high tide form the transition between the terrestrial and marine

environment; this habitat is discussed in EES Volume 3 Environmental Effects of

the Desalination Plant.











Technical Appendix

Chapter 3 Interactions with

the marine environment

3-2 Chapter 3 Interactions with the marine environment

Figure 3-1 Characteristics of the marine environment

3.1.1 Intertidal habitats

Intertidal habitats are located in the shore between the highest and lowest

tides. These habitats are alternately exposed to the air and the sea with the

movement of the tides, and the communities that inhabit these intertidal areas

are able to tolerate these conditions. The majority of intertidal habitats from

Kilcunda to Coal Point comprise sandy habitats, with small patches of rocky reef

scattered along the coastline. Small seaweeds, snails and limpets dominate the

intertidal community. At high tide, when these habitats are submerged, small

reef fish also live in these areas.


3.1.2 Subtidal habitats

Subtidal habitats are those that are located below the mean low-water mark

and are almost always continuously submerged. This area experiences variable

environmental conditions, including substantial influence from physical factors

such as turbulence caused by wave action. Subtidal habitats offshore from the

Project comprise a mosaic of scattered reef of varying relief interspersed with

small patches of soft sediments. The subtidal reefs and sand patches provide

habitat for a wide range of seaweeds, invertebrates and fish species.

3.1.3 Pelagic habitat

The pelagic environment (open ocean) of Bass Strait incorporates a relatively

broad area of shallow continental shelf. The biological community found in the

open ocean consists of plankton, fish and larger mammals such as whales and

dolphins. Plankton consists of minute organisms that live in the water column.

3.2 Impact pathways for the risk and impact assessment

Project activities may affect environmental values through a variety of impact

pathways. A single action or activity may have a number of impact pathways.

For example, clearing of the seabed for construction may affect reef biota and

sandy benthic biota. The risk assessment and impact assessment methodologies

adopted for the EES are based on an analysis of the impact pathways.

3.3 Risk Assessment

The risk assessment process, as a framework for the impact assessment, is

described in detail in Volume 1, Chapter 7 and in the Risk Assessment report

(Maunsell 20081, Technical Appendix 6). The risk assessment process relevant

to the Marine Structures has been applied across all EES assessment areas.

The risk assessment process identifies the impact pathways associated with

each Project activity and assigns a consequence rating to the impact if it

materialised. The next step is to consider and assign a rating to the likelihood of

that impact occurring. The combination of consequence by likelihood is the risk

rating, using the matrix in Table 3-1.


Table 3-1 Risk Assessment Matrix

Consequences

Likelihood Negligible Minor Moderate Major Extreme

Rare

Low Low Low Medium High

Unlikely

Low Low Medium Medium High

Likely

Low Medium Medium High High

Almost certain

Medium Medium High High Critical

Certain

Medium Medium High Critical Critical

The effect of applying the risk matrix is that a risk that is rare but would have

an extreme consequence it if did occur is allocated a high risk rating. A risk that

is certain and has only a moderate consequence is also allocated a high risk

rating. It is therefore necessary to consider the impact pathway both in terms of

consequence and its likelihood for the development of potential management

and mitigation measures in response to significant risks.

However, the risk matrix automatically designates any risk that is ‘likely’ as

being ‘medium’ or higher unless its consequence is ‘negligible’. While this

ensures that likely risks are given appropriate prominence in the impact

assessment and that remote risks with major (or above) consequences are

appropriately recognised and managed to ensure that they do not eventuate,

the risk ratings should not be confused with the outcomes of the impact

assessment, which consider the likely impacts of the Project and focuses

on consequence.

One of the key aims of the risk assessment process was to ensure a consistent

assessment of consequence and likelihood across the broad range of specialist

areas relevant to the Project. To achieve this, Consequence and Likelihood

Tables were developed.


3.4 Approach for Impact Assessment

All risks identified in the risk assessment were considered in the impact

assessment. As the impact assessment was also used to define or refine the

consequence and likelihood components of the risk analysis, some of the

conclusions in the technical investigations presented in the Technical Appendices

to this EES are expressed in the language of risk. However, this occurs in a

minority of cases and, where it does, a conservative approach has been applied

to the consequence rating in the risk assessment, which is then taken to be the

relevant rating for the impact assessment.

The predominant purpose of the impact assessment is to draw conclusions,

on balance, as to the likely impacts of the Project in the context of existing

conditions and the measures that are available to mitigate its likely impacts.

The impact assessment chapters focus on the risks with a rating of medium and

higher, with some distinction given to the likelihood of the impact pathway

occurring. These risks are summarised in the sections below. A limited

discussion of risks with a low rating is also provided to address issues raised

during community consultation for the EES.

3.5 Construction activities and risk assessed medium and above

As set out in Chapter 2, the Project activities expected to occur during

construction are listed below:

• seabed clearing and disturbance for placement of self-elevating platform

(SEP or ‘jack-up barge’)

• tunnelling and drilling

• movement of vessels

• use of artificial night lighting

• use of chemicals and hydrocarbons (on SEP)

• seismic activities including use of air guns

• use of construction divers

• temporary construction exclusion zone.


The risks assessed as medium or higher associated with the construction of the

Marine Structures are set out in Table 3-2. While the impact assessment is not

confined to these risks, the table identifies the higher order risks.

Table 3-2 Summary of construction environmental risks for the Marine Structures assessed as medium and higher

Activity Impact pathway

Con

sequ

ence

Like

lihoo

d

Ris

k

Marine biota and ecosystems

Seabed clearing Removal or damage of reef habitat Moderate Certain High

Use of chemicals and

hydrocarbons

Small chemical/hydrocarbon spill or incident impacting on

marine biota and ecosystems

Minor Almost

certain

Medium

Seabed clearing Removal or damage of sandy habitat Minor Likely Medium

Seabed clearing Destruction of or disturbance to significant reef species Moderate Likely Medium

Use of air guns Noise and vibration from air guns impacting on fish Moderate Likely Medium

Use of air guns Noise and vibration impacting on smaller toothed cetaceans,

mammals and sea birds

Minor Likely Medium

Impact Pile driving Noise and vibration impacting on fish Moderate Likely Medium

Geophysical surveys Noise and vibration from geophysical surveys other than air

guns impacting on fish

Minor Likely Medium

Production of drilling

spoil

Release of spoil at the drill site impacting on reef biota and

ecosystems

Minor Likely Medium

Production of drilling

spoil

Disposal of spoil at a selected oceanic location impacting on


Minor Likely Medium

Movement of marine

vessels

Introduction of flora and fauna marine pests from marine

vessels impacting on marine species

Major Unlikely Medium

Use of construction

divers

Introduction of abalone disease impacting on abalone

communities



hydrocarbons

Medium or significant chemical/hydrocarbon spill or incident

impacting on water column, intertidal marine biota and marine

ecosystems

Moderate Unlikely Medium

Increased access to

Williamsons Beach

People accessing Williamsons Beach impacting on threatened

fauna




Con

sequ

ence

Like

lihoo

d

Ris

k


hydrocarbons

Medium or significant chemical / hydrocarbon spill or incident

impacting on the marine park

Major Rare Medium

Human health and safety, access and visual amenity

Movement of marine

vessels

Increase in marine traffic impacting on fishing and recreational

activities

Minor Almost

Certain

Medium

Movement of marine

vessels

Increase in marine traffic impacting on public safety Major Rare Medium

Socio-economic

All construction

activities

Social impacts of construction of Marine Structures – impacts

on amenity

Minor Certain Medium

All construction

activities

Potential for reduced visitation and loss of business revenue

due to perception that the Wonthaggi / Kilcunda coastline is

becoming ‘industrialised’

Moderate Almost

certain

High

Construction

Exclusion zone

Impacts on commercial fishing Minor Likely Medium

Use of construction

divers

Introduction of abalone disease impacting on commercial

viability of abalone diving industry in the Project area

Extreme Unlikely High

The above risk assessment is based on accepted construction practices but does not take into account the mitigation measures

embodied in the Performance Requirements. If the PRs are taken into account, both the likelihood and consequence of the risks

may be significantly lower.

Some of these risks are shown schematically in Figure 3-2.


Figure 3-2 Conceptualisation of construction activities and risks for the Marine Structures in the Reference Project

3.6 Operation and risks assessed medium and above

As set out in Chapter 2, the Project activities expected to occur during operation

are listed below:

• intake of seawater

• discharge of concentrate

• operation exclusion zone.


The risks assessed as medium and above associated with the operation of the

Marine Structures are shown in Table 3-3. While the impact assessment is not

confined to these risks, the table identifies the higher order risks.

Table 3-3 Summary of operational environmental risks for the Marine Structures assessed as medium and above


Con

sequ

ence

Like

lihoo

d

Ris

k

Marine biota and ecosystems

Entrainment of eggs / larvae with localised release, short life

history and becoming adults nearby (if intake located over a reef

environment)

Moderate Certain High

Entrainment of eggs / larvae with localised release, short life

history and becoming adults nearby (if intake located over a sandy

environment)

Minor Likely Medium

Entrainment of eggs / larvae that are remotely spawned, have long

duration, settle in particular places (if intake located over a reef

environment)



duration, settle in particular places (if intake located over a sandy

environment)

Negligible Certain Medium

Entrainment of eggs / larvae that are released over wide areas,

have long duration and do not settle in particular places


Entrainment of eggs / larvae that have widespread distribution,

short life cycle and rapid turnover


Impingement, entrainment and entrapment of fish and mobile

macroinvertebrates

Minor Likely Medium

Intake of seawater

Flow on effects from seawater intake – impacts on ecosystem

interactions

Moderate Likely Medium

Discharge of saline

concentrate

Flow on effects from saline concentrate discharge – impact on

ecosystem interactions

Minor Likely Medium



Con

sequ

ence

Like

lihoo

d

Ris

k

Socio-economic

Operational

exclusion zone

Impact on commercial fishing activities through restricted fishing

areas

Minor Likely Medium

The above risk assessment is based on accepted operation practices but does not take into account the mitigation measures

embodied in the Performance Requirements. If the Performance Requirements are taken into account, both the likelihood and

consequence of these risks may be significantly lower.

Some of these risks are shown schematically in Figure 3-3.

Figure 3-3 Conceptualisation of the operation of the Marine Structures in the Reference Project

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4.0 Marine physicalenvironment

Chapter 4 Marine physical environment 4-1

4 Marine physical environment

This chapter describes the marine physical environment that influences the

marine ecology of the Project area and is based on specialist investigations from

the following reports:

• ASR (20082) Description of the Bass Strait Physical and Geographical Marine Environment (Technical Appendix 19)

• ASR (20084) South-east Australian Hydrodynamic model: Calibration and Validation (Technical Appendix 21)

• ASR (20081) Bass and Bays Model: Calibration and Validation

(Technical Appendix 18)

• ASR (20083) Local fine-resolution model: calibration and validation


• GHD (20083) Water and Sediment Quality Assessment (Technical

Appendix 23)

• Bassett (2008) Underwater noise (Technical Appendix 22)

• Rosengren, N. and Boyd, C. (20081) Desalination Project, Desalination Plant Site, Existing Conditions (Technical Appendix 37).

ASR conducted field investigations and hydrodynamic modelling to understand

the physical marine environment at the Project area. Field surveys characterised

the ocean climate, and water quality and sediments were sampled.

Hydrodynamic models have then been used to understand the existing oceanic

environment in Bass Strait and in the Project area.











Technical Appendix

Chapter 4 Marine physical environment

4-2 Chapter 4 Marine physical environment

4.1 Hydrodynamic modelling

Mathematical or numerical models have long been used to investigate marine

and coastal conditions in order to understand the impact of modifications on the

environment. Over time increased technology has led to an increase in

complexity and reliability of these models. Hydrodynamic models have been

used for the Project to characterise the existing marine environment and to

assist in the marine ecology impact and risk assessment (Chapters 7 and 8 of

this Volume). This relationship is shown in Figure 4-1.

Figure 4-1 Hydrodynamic model inputs and outputs

A number of numerical models have been developed for predicting the potential

impacts of the Reference Project on the marine environment. The type of model

used depends on the spatial area being modelled. These models and their

application are described in detail in the Technical Appendices listed above in

the introduction to this Chapter.

Table 4-1 lists the models used for the Reference Project and their spatial

scales. A fifth model, the VisJet Diffuser Model was used to simulate the

behaviour of the saline concentrate in the immediate vicinity of the diffuser.


Table 4-1 Spatial scale of the hydrodynamic models

Model Spatial scale

Oregon State University

Tidal Model

Models tidal levels at a global scale.

South-east Australian

Hydrodynamic Model

Models hydrodynamics at a regional scale. The model was

used to simulate existing water circulation within Bass Strait

and forms the basis for larval transport studies.

Bass and Bays Model Models hydrodynamics within Port Philip Bay, Western Port

and the adjacent coastal and offshore areas between Cape

Otway and Cape Liptrap and forms the basis for larval

transport studies.

High-resolution Local

Model

Models hydrodynamics at the local scale within a few

kilometres of the proposed Marine Structures.

4.1.1 Calibration and validation of models

Calibration and validation of hydrodynamic models is necessary to ensure that

they appropriately represent the hydrodynamic processes in Bass Strait and the

Project area informs the impact assessment process. Calibration is the process

of adjusting the parameters used in the model so that the model results provide

an acceptable approximation to a set of measured values.

Validation occurs after calibration, when modelled values generated using the

calibrated model are compared with additional measured data, which were not

used in the calibration process, in order to confirm the model’s ability to

reproduce the phenomena required. The calibration and validation periods and

locations for the hydrodynamic models are described in Table 4-2.


Table 4-2 Calibration and validation locations and period for hydrodynamic models

Model South-east Australian Hydrodynamic Model Bass and Bays Model Local Model

Calibration and

validation

locations

Water levels at Portland, Lorne,

Project area, Burnie and Spring

Bay and current velocity at the

Project area

Water levels at Lorne, Geelong,

Williamstown, Stony Point and

the Project area and current

velocity at Project area

Longshore and cross-shore currents

velocities at the Project area

measured at the 24 m isobath and

currents at the upper, middle and

the lower parts of the water column

Calibration

period

September to October 2007 September to October 2007 September to October 2007

Validation

period

February to April 2008 February to April 2008 March to April 2008

Calibration and validation of these models is discussed further in the relevant

technical appendices (South-east Australian Hydrodynamic Model: ASR 20084,

Technical Appendix 21; Bass and Bays Model: ASR 20081, Technical Appendix

18; Local Model: ASR 20083, Technical Appendix 20).

4.2 Landforms and bathymetry

Coastal areas are dynamic places that are influenced by climatic, geological and

fluvial processes.

4.2.1 Landforms

The coastline near the Project area extends from south of Kilcunda to Cape

Paterson and is straight and well defined. The coastline is oriented north-

northwest to south-southeast. There are five distinct coastal units within this

area that are based on morphology, coastline materials and coastal processes.

These are discussed in detail in Rosengren and Boyd 20081, Technical

Appendix 37.


The Marine Structures are located offshore of coastal unit 3. The landform

includes:

• shore platforms

• beaches

• rock cliffs and bluffs

• foredunes

• transgressive dunes.

Cretaceous sandstone shore platforms are a feature of the coastline immediately

south of the Powlett River. The platform is intertidal and half-covered by sand

(Rosengren and Boyd 20081, Technical Appendix 37). Beaches are continuous

along this stretch of coast and are composed of relatively clean sands with

evidence of high degree of sand movement from heavy wave action (CEE 2008,

Technical Appendix 31). Below the low water mark the beach features extensive

rock platforms and channels scoured by rips. The beach is moderately steep. No

beach berm development was observed during field inspections and the

backshore zone features a well-defined foredune scarp (Rosengren and Boyd

20081, Technical Appendix 37).

4.2.2 Bathymetry

The Project area is located in Bass Strait, which covers an area approximately

400 kilometres long and 200 kilometres wide between the south-east coast of

Victoria and the north coast of Tasmania. The bathymetry of Bass Strait is bowl-

shaped, with a shallower rim on the eastern and western entrances to the Strait

and a deeper centre. Depths in the middle of Bass Strait are around 80 to 85

metres. Figure 4-2 shows the bathymetry of Bass Strait in the vicinity of the

Project area (ASR 20082, Technical Appendix 19).


Figure 4-2 Bathymetry of the Project area extending into Bass Strait

Source: ASR 20082

The Project area is exposed to tides, waves and winds, and the seafloor drops

away from the coast in contours parallel to the beach area, with no obvious

major features (as shown in Figure 4-3).

Figure 4-3 Project area bathymetry

Source: ASR 20082


4.3 Hydrodynamic processes

Hydrodynamic processes drive water and sediment movements that influence

the water column and seabed form and hence play a role in shaping marine

communities. Modelling shows that the Project area receives some of the

highest wave energy in Victoria. There are no significant headlands, coves or

bays between Kilcunda and Cape Paterson, so marine biological communities in

the Project area are all subject to high incident wave energy.

Water movements at the Project area include periods of strong wave action,

currents, upwelling and downwelling. These water movements are discussed in

detail in this section, and this information is sourced from field measurements

and modelled data.

4.3.1 Wind climate

Wind throughout the region affects hydrodynamic processes including wave

action, non-tidal currents and upwelling and downwelling. Wind appears to be

the dominant driving force for longshore currents at the Project area

(ASR 20082, Technical Appendix 19).

South-westerly winds dominate the Project area with speeds of up to 25 metres

per second. Wind data from 1997 to 2007 is summarised in Figure 4-4. Data

analysis indicates an average wind speed within Bass Strait of approximately

8.3 metres per second, with maximum continuous speeds of up to 44.6 metres

per second.


Figure 4-4 Wind Rose for Bass Strait 1997 to 2007

Source: ASR 20082

4.3.2 Wave climate

The western Victoria coastline is regularly subjected to south-western Southern

Ocean swells (Figure 4-5). The Project area is exposed to swells of

approximately two metres with waves up to 7.7 metres high; seabed

topography and landforms cause localised differences in wave energy.


Figure 4-5 Offshore wave climate at Project area

4.3.3 Currents

Currents in Bass Strait vary spatially and temporally. Ocean currents at the

Project area are mostly parallel to the shore. Strongest net currents occur

generally in spring and summer. Lowest net currents are likely to occur during

periods of calm in autumn. Currents in the area are driven by:

• tide

• wind

• density effects

• coastal-trapped waves.


Tidal currents

The Project area in central Bass Strait experiences tidal currents that run parallel

to the coast with typical strengths between 0.04 to 0.08 metres per second

reaching up to 0.2 metres per second further offshore. Tidal flows in Bass Strait

come from the east and west during an increasing (flood) tide, and flow out to

the east and west during a dropping (ebb) tide, as shown in Figure 4-6.

Figure 4-6 Peak ebb (left) and flood (right) tidal currents within Bass Strait

Source: ASR 20084

During flood tides, tidal currents move in a clockwise direction (south-easterly

direction) in Bass Strait between Cape Otway and Cape Liptrap and at ebb tides,

the waters between Cape Otway and Cape Liptrap move anti-clockwise (north-

westerly direction) as shown in Figure 4-7.


Figure 4-7 Typical peak flood (upper) and ebb (lower) tidal currents within northern Bass Strait

Source: ASR 20081

Wind-driven currents

Non-tidal currents in Bass Strait are influenced by wind and coastal-trapped

waves. Modelled of data from 2004 indicate that non-tidal currents generally run

west to east and are most intense along the Victorian coastline and the northern

and eastern coasts of Tasmania. This is shown in Figure 4-8. The arrows show

currents moved in a predominantly easterly direction (ASR 20081, Technical

Appendix 18).


Wind-driven circulation is relatively fast on the shelf near Portland and along

the east Gippsland coast. However, the strength of wind-driven currents at the

Project area may differ as they are influenced by local coastal morphology.

Typical wind-driven current strengths around the Project area are anticipated to

be less than 0.1 metres per second (ASR 20082, Technical Appendix 19).

Figure 4-8 Non-tidal current modelling results (September-October 2007) for northern Bass Strait

Source: ASR 20081

At the Project area, currents are dominated by wind driven longshore currents

(Figure 4-9). The influence of the wind increases the magnitude of the

longshore current at the surface. Deeper in the ocean, the seabed tends to slow

the longshore current (ASR 20083, Technical Appendix 20).


Figure 4-9 Results for non-tidal current modelling from September to October 2007 at the Project area

Source: ASR 20081

Density driven circulation

Ocean circulation can be influenced by differences in water density due to

variations in salinity and temperature. Very little is known about these density-

driven effects in Bass Strait. Density-driven circulation is expected to be very

slow at the Project area and these currents are likely to be influenced by

Western Port and the Powlett River (ASR 20082, Technical Appendix 19).


Coastal trapped waves and upwelling/downwelling

Coastal-trapped waves (or Kelvin waves) are formed by high or low-pressure

weather systems with associated winds and propagate into Bass Strait as a

result of the continental shelf between Tasmania and Victoria. They are

essentially characterised as a rise and fall of water that may occur over a

period ranging from hours to days. They propagate from west to east under

the Coriolis effect and are expected to reach the Project area from as far away

as Western Australia. Coastal-trapped waves are often evident as a rise and fall

of the water level in tidal gauge measurements at Portland.

Upwelling is the movement of deep ocean waters to the surface, which in Bass

Strait is caused by coastal-trapped waves. Upwellings in other parts of the world

can bring nutrient-rich bottom waters to the surface. However, this is not the

case at the Project area as the continental shelf is wider and shallower inside

the strait so deep, nutrient-rich ocean bottom water is absent or dilute.

Winds at the Project area can also cause upwelling and downwelling. Onshore

winds tend to push surplus warm surface water up against the coast, leading to

downwelling. Offshore winds have the opposite effect leading to upwelling.

Satellite imagery showing sea surface temperature was used to determine the

occurrence of upwelling and downwelling and to assess the relationship with

wind direction. Colder water in the Project area along the coast corresponds

with offshore winds from the north-east; the opposite occurs with onshore

winds from the south-west (ASR 20082, Technical Appendix 19).

4.4 Sediments

The seabed of Bass Strait is characterised by a wide variety of bed types that

are related to tidal currents. Wave energy is also correlated with sediment grain

size and is responsible for many of the sandy subtidal margins around the Strait.

Near-shore sediment deposits consist of coarse sands with isolated pockets

of very coarse sand to granules amidst regions of higher proportions of large

shells and pebbles. The sediments become progressively finer with distance

from the shore.


The Project area has calcareous, mixed grain sediments. Sediment quality

sampling was undertaken in April 2008 offshore of the Desalination Plant site.

Sediment samples were dominated by fine to coarse grained, sub-angular to

rounded sands. The sands consisted of calcareous and quartz deposits with

10 to 50 per cent shell grit and reef debris. Sand grain results are presented in

Table 4-3.

Table 4-3 Sediment particle size analysis

Sediment type Size Classification Average per cent composition (from all samples)

Fine–coarse gravel Greater than 2.36 mm 1.4%

Medium–coarse sand 0.3 - 2.36 mm 77%

Fine sand 0.075 - 0.3 mm 15%

Silt and clay Less than 0.075 mm 6.6%

Source: GHD 20083

Sediment sampling included analysis of the concentration of metals and

metalloids, nutrients and organic compounds. Sediment quality was compared

with the low and high interim sediment quality guidelines in the Australian and

New Zealand Guidelines for Fresh and Marine Water Quality. As expected, all

metals were below the lowest interim sediment quality guideline. Organic

compounds, including petroleum hydrocarbons, organochlorine pesticides and

polyaromatic hydrocarbons, were below the laboratory limits of reporting (GHD

20083 Technical Appendix 23).

Water movements (i.e. currents and waves) can disturb and suspend sediment,

and sediment can be carried great distances; this suspension and settling

depends on the sediment grain size and density, and current velocity. At the

Project area, during extensive periods of large swell, settled sediments can be

re-suspended. Generally, in water greater than 40-metres deep, there is less

water movement so finer sediments such as muds settle to the seafloor.

Sediment transport modelling indicates that sediment from Western Port may be

transported to the Project area (ASR 20082, Technical Appendix 19). However,

sandy sediments in the area can be resuspended by wave action and are

unlikely to accumulate in the area (GHD 20083, Technical Appendix 23).


4.5 Water quality

The State Environment Protection Policy (Waters of Victoria) (SEPP WoV) is

the primary State policy for surface water quality. The SEPP (WoV) specifies

beneficial uses that require protection in open coasts. Environmental quality

objectives (or trigger values from the Australian and New Zealand Guidelines for

Fresh and Marine Water Quality) from SEPP (WoV) are typically adopted in order

to provide guidance on the concentration or level of an indicator (chemical or

biological) required to protect beneficial uses (i.e. a current or future

environmental value or use of the waters that the community wants to protect).

Water quality sampled in the ocean environment has been compared with SEPP

(WoV) environmental quality objectives (GHD 20083 Technical Appendix 23).

Appropriate trigger values to protect beneficial uses outside the mixing zone

surrounding the outlet are discussed in Chapter 8 of this Volume.

4.5.1 Sampling methods

Several sites near the Project area were sampled for a variety of water quality

parameters since June 2007 at two primary sampling sites. Two additional sites

were monitored infrequently to analyse the influence of the Powlett River on

local water quality. Water-quality sampling was undertaken at depths of

one metre below the surface and two to three metres above the seabed to

account for possible variations in water chemistry from temperature

stratification. The broad intent of the program was to characterise the chemical

composition of the seawater, identify seasonal trends, identify potential

contamination sources and derive ambient (or local) water quality trigger values.

The monitoring program included a broad range of parameters to satisfy both

design and environmental purposes, including:

• temperature

• pH

• total alkalinity

• light attenuation

• salinity

• nutrients

• chlorophyll-a

• silica


• dissolved oxygen

• suspended solids

• turbidity

• toxicants

• other factors generally of interest to the Project (e.g. metals, bacterial

counts and biological compounds).

4.5.2 Sampling results

Water quality at the Project area is primarily oceanic, with influences from the

Powlett River and Western Port (CEE 2008, Technical Appendix 31). Water

quality results are within the range expected for open oceans. Water quality for

major ions at the Project area is reflective of open oceans. The sampling found

that all major ions (i.e. chloride, sulfate, sodium, magnesium, potassium,

calcium) varied within approximately 10 per cent over the sampling period while

the concentration of other ions (e.g. fluoride, boron) varied little throughout the

sampling period.

Table 4-4 Ion balance for marine water at the Project site

Ion Median concentration (mg/L)

Chloride 20 200

Sodium 11 430

Sulfate 2 910

Magnesium 1 400

Potassium 490

Calcium 420

Bromide 62

Strontium (total) 7.6

Barium (total) 5.9

Boron (total) 4.3

Fluoride 0.9

Source: GHD 20083


Salinity at the Project area varies both seasonally and with depth. Surface

salinities ranged from 34.7 to 36.1 psu during the monitoring period. Depth

profiles indicate salinity stratification during winter and spring sampling (Figure

4-10). Lower salinities in the surface layer occurred during July, August,

September and November, which may have been caused by Powlett River flows.

Stratification was only evident in the first four metres below the ocean surface.

Figure 4-10 Salinity though water column in Project area

16/08/07

13/09/07

13/11/07

15/02/08

0

2

4

6

8

10

12

14

16

18

20

34.5 35 35.5 36 36.5Salinity

Dept

h (m

)

14/06/07 D 11/07/07 D 31/07/07 D 16/08/07 D 30/08/07 D 13/09/07 D 26/09/07 D 17/10/07 D 30/10/07 D

13/11/07 D 19/11/07 D 28/11/07 D 6/12/07 D 12/12/07 D 19/12/07 D 10/01/08 D 17/01/08 D 23/01/08 D

31/01/08 D 6/02/08 D 15/02/08 D 19/02/08 D 05/03/08 D 06/03/08 D 01/04/08 D

30/08/07

31/07/07

06/03/08

01/04/08

06/02/826/09/07

Source: GHD 20083

Surface temperature results vary seasonally between 11.9ºC and 20.9ºC and

there is evidence of stratification in spring and early summer with temperatures

up to two degrees warmer at the surface (Figure 4-11). Oceanographic

measurements also indicate temperature stratification with the surface up to

3ºC warmer than the seabed.


Figure 4-11 Temperature of water column at Project area

14/06/07

31/07/07

16/08/0730/08/07

13/09/07

26/09/07

17/10/07

30/10/07 13/11/07

19/11/07

28/11/07

6/12/07 12/12/07

19/12/07 10/01/08

17/01/08

23/01/08

31/01/08

6/02/08

15/02/08 19/02/08

06/03/08

28/05/08

0

5

10

15

20

10 12 14 16 18 20 22

Temperature (oC)

Dep

th (m

)

14/06/07 D 11/07/07 D 31/07/07 D 16/08/07 D 30/08/07 D 13/09/07 D 26/09/07 D 17/10/07 D 30/10/07 D

13/11/07 D 19/11/07 D 28/11/07 D 6/12/07 D 12/12/07 D 19/12/07 D 10/01/08 D 17/01/08 D 23/01/08 D

31/01/08 D 6/02/08 D 15/02/08 D 19/02/08 D 05/03/08 D 06/03/08 D 01/04/08 D 28/05/08 D

Source: GHD 20083

Oxygen is vital for marine and aquatic organisms. At the Project area, dissolved

oxygen (DO) was often over 100 per cent saturation and tended to decrease

slightly with depth from the surface, as shown in Figure 4-12.


Figure 4-12 Dissolved Oxygen (DO) depth profile from sampling site

17/10/07

6/12/07

12/12/07

23/01/08

19/02/08

0

2

4

6

8

10

12

14

16

18

20

80 85 90 95 100 105 110 115

DO (% Saturation)

Dep

th (m

)

14/06/07 D 11/07/07 D 31/07/07 D 16/08/07 D 30/08/07 D 13/09/07 D 26/09/07 D17/10/07 D 30/10/07 D 13/11/07 D 19/11/07 D 28/11/07 D 6/12/07 D 12/12/07 D19/12/07 D 10/01/08 D 17/01/08 D 23/01/08 D 31/01/08 D 6/02/08 D 15/02/08 D19/02/08 D 05/03/08 D 06/03/08 D 01/04/08 D 28/05/08 D

TV = 90% TV = 110%

Chlorophyll-a, a plant pigment, is generally used to determine phytoplankton

biomass. Chlorophyll-a concentration measured at the Project area was similar

to the concentration found for other studies in the Bass Strait (CEE 2008,

Technical Appendix 31). Chlorophyll-a concentrations varied throughout the

monitoring period and peaked in June, September and December; the median

concentration for the monitoring period is 0.55 µg/L.

Suspended solids and light

The productivity of the marine environment is affected by light penetration

through the water column. Photosynthetically available radiation (PAR)

measures the amount of light available in the wavelengths used for

photosynthesis. PAR is affected by the amount of dissolved substances and

particulate content in the water (e.g. sediment, plankton abundance, organic

matter) as well as weather conditions. PAR measured at the Project area

decreased with depth at a variable rate throughout the monitoring period.

The median value was a PAR attenuation unit of 0.17 m-1 in calm conditions.


Turbidity, a measure of water clarity, was generally below the limit of detection.

However, divers have observed that underwater visibility is highly variable. For

example, underwater video surveys for the Project area found substantially

reduced visibility due to suspended solids, particularly within two metres of the

seabed (CEE 2008, Technical Appendix 31).

Total suspended solids (TSS) is a measure of the amount of suspended

particulate mater in a water sample. TSS measures varied throughout the

sampling period.

Nutrients

Nutrients are essential for primary producers such as phytoplankton, algae and

other marine plants. Bass Strait is generally a low nutrient environment,

although seasonal trends do occur throughout the Strait. Nutrient

concentrations generally rise to higher levels at the west and eastern edges

during winter. This is particularly the case for nitrates and nitrites, although not

for ammonia (GHD 20083, Technical Appendix 23). It is suggested that nutrient

input into Bass Strait occurs from the deeper waters in the east and west and

nutrients are used as soon as they enter Bass Strait leaving a very limited

nutrient supply to the interior. As expected, sampling results show low nutrient

concentrations in Project area.

Nitrogen and phosphorus concentrations from the monitoring period are

generally similar to other water quality studies in the region. Median values for

these nutrients are shown in Table 4-5. Nitrogen shows a seasonal pattern at

the Project area and is shown in Figure 4-13 and Figure 4-14. Total ammonia

(NH4+) has a median concentration was 0.008 mg/L. Total Kjeldahl nitrogen

(TKN) values are close to the total nitrogen values indicating that most of the

nitrogen is in an organic form and organic material is the main source of

nitrogen in seawater at the Project area.

Table 4-5 Existing nutrient water quality parameters

Parameter Unit Median

Total NH4+ mgN/L 0.01

NO3-+ NO2

- mgN/L 0.06

TN mgN/L 0.18


Parameter Unit Median

SRP mgP/L 0.004

TP mgP/L 0.01

Source: GHD 20083

Figure 4-13 Total nitrogen and total Kjeldahl nitrogen at the Project area from June 2007 to June 2008

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1/06/20

07

1/07/2

007

1/08/2

007

1/09/20

07

1/10/2

007

1/11/2

007

1/12/2

007

1/01/2

008

1/02/20

08

1/03/2

008

1/04/2

008

1/05/2

008

1/06/2

008

TN, T

KN

(mgN

/L)

TKN Total Nitrogen

Source: GHD 20083


Figure 4-14 Total ammonia nitrogen, nitrate and nitrite and combined total of all, at the Project area from June 2007 to June 2008

0.00

0.01

0.02

0.03

0.04

0.05

1/06/2

007

1/07/2

007

1/08/2

007

1/09/2

007

1/10/2

007

1/11/2

007

1/12/2

007

1/01/2

008

1/02/2

008

1/03/2

008

1/04/2

008

1/05/2

008

1/06/2

008

TAN

, NO x

, TA

N+N

O x (m

gN/L

)

TAN (Total Ammonia Nitrogen) NOx (Nitrate + Nitrite) TAN + NOx

Source: GHD 20083

Phosphorus concentrations measured for the Project area are presented in

Figure 4-15. Soluble reactive phosphorus (SRP) concentrations were stable

throughout most of the sampling period. The mean concentration was

0.007 mg/L. Total phosphorus (TP) showed more variability than SRP. SRP

measurements were lower than TP, which indicates that most of the phosphorus

is in an organic form at the Project area (GHD 20083, Technical Appendix 23).


Figure 4-15 Phosphorus concentration at the Project area from June 2007 to June 2008

0.00

0.01

0.02

0.03

0.04

1/06/2

007

1/07/20

07

1/08/2

007

1/09/20

07

1/10/20

07

1/11/2

007

1/12/2

007

1/01/20

08

1/02/2

008

1/03/20

08

1/04/2

008

1/05/2

008

1/06/2

008

SRP,

TP

(mgP

/L)

Soluble Reactive Phosphorus Total Phosphorus

Source: GHD 20083

Metals

Metals occur naturally within the marine environment. Natural sources of metals

include erosion of ore-bearing rock, atmospheric deposition and riverine inputs.

The Project area is expected to have normal concentrations of metals and low

levels of toxicants that are within the range expected for open oceans.

Median values for dissolved and total metals are presented in Table 4-6 (GHD

20083, Technical Appendix 23). The concentration of most metals varied little

over the sampling period and most concentrations were below the laboratory

limit of reporting. Iron and aluminium concentrations were most variable of all

the metals, but they were also generally below the laboratory limit of reporting.


Table 4-6 Median metal concentrations at the Project area from June 2007 to June 2008

Parameter Median (µg/L)

Al 13.8

Fe 16.9

As 1.6

Cd 0.1

Cr 0.23

Cu 0.25

Pb 0.1

Mn 0.58

Hg 0.05

Mo 11.3

Ni 0.18

Zn 1.75

Total Cn 2.25

Source: GHD 20083

Organic compounds

Organic compounds including oils and grease were measured, although the

Project area is not expected to have significant concentrations of these

chemicals. All parameters were below the level of reporting with the exception

of oil and grease, which had a concentration of 6.0 mg/L during March 2008.


4.6 Underwater noise

In an open ocean there is a natural level of noise created by the existing

environment. Natural sources of underwater sound and noise include breaking

waves, wind, bubbles, seismic anomalies and sound from a variety of marine

organisms (from crustaceans through to cetaceans). Human noise sources

include recreational activities, shipping and sonar. These noises have varying

frequencies depending on their source (Table 4-7). Typically, lower to middle

frequency noises are generated by human activities. Higher frequency

noise is dominated by thermal noise (generated by the random motion

of water molecules).

Table 4-7 Dominant ambient sound sources and their emission frequencies

Sound Typical Frequencies (kHz)

Distant shipping 0.02 – 0.5

Breaking waves 0.5 – 100

Thermal noise Greater than 100

Source: Basset 2008

Intermittent noises may also occur in the marine environment. In the

open ocean these transient noises include rain, lightning and undersea seismic

activity (e.g. undersea volcanic eruption and earthquakes). Biological sources

of intermittent noise include the communication and navigation systems of

cetaceans. Cetacean underwater noise may occur over a range of frequencies

from less than 10 Hz to greater than 200 kHz.

Ambient noise was measured on 2 May 2008 at a range of locations in the

vicinity of the Project in 18-metre deep water at approximately eight metres

below the water surface. During sampling the wind speed was approximately

13 metres per second with two to three metre swells. The overall underwater

ambient noise level at the Project area was approximately 117 decibels between

the frequencies of 20 Hz and 10 kHz. (This is presented in detail in Bassett

2008, Technical Appendix 22.)


The Project area is a high-energy coastal environment that is frequently

exposed to strong onshore wind and wave action. Bathymetry in the Project

area has no obvious major features and is therefore not expected to significantly

affect sound propagation.

Major shipping lanes are located 20 kilometres to the south of the Project area

and are not expected to produce any noise greater than the background noise

level. At present there are no significant underwater marine noise sources in the

area generated by human activities (Basset 2008, Technical Appendix 22).

5.0

Ma

rine

eco

log

ical e

xistin

g co

nd

ition

s

5.0 Marine ecologicalexisting conditions

Chapter 5 Marine ecological existing conditions 5-1

5 Marine ecological existing conditions

This chapter presents the existing conditions of the marine environment in

the vicinity of the Project area, including marine habitats and marine ecology.

This chapter summarises the findings of specialist investigations from the

following reports:

• Biosis Research (20082) Assessment of Marine Mammals, Birds and Reptiles for the Desalination Project, Bass Coast, Victoria (Technical Appendix 13)

• Consulting Environmental Engineers (CEE) (2008) The Desalination Project Marine Biology (Technical Appendix 31)

• GHD (20084) The Desalination Project Invasive Marine Species Specialist Report (Technical Appendix 27).

Marine surveys of the Project area are limited. However, extensive research

has been undertaken previously in and around Bunurong Marine National Park.

Existing conditions information presented in this section is based on results from

previous work undertaken on Bunurong National Park as well as recent Project-

specific surveys and other relevant literature.

5.1 Regional context

The Project area is located near to the Powlett River and its estuary. Parts of

the marine and coastal areas in the region are afforded State and National

protection. These areas are also noted for their natural and social values.











Technical Appendix

Chapter 5 Marine ecological existing conditions

5-2 Chapter 5 Marine ecological existing conditions

5.1.1 The Powlett River

The Powlett River discharges into Bass Strait in South Gippsland, and the

Powlett River estuary is approximately one kilometre from the proposed

Desalination Plant location. The River has a catchment area of approximately

500 square kilometres.

The Powlett River behaves like a typical southern Australian estuary; it is closed

to the sea for a portion of the year when rainfall is low. It is naturally open to

the sea at various times during the year, generally between May to November,

with July, August, September and November being the most likely months when

there is a direct connection between the estuary and the sea. Even with the

closures a number of fish will utilise the estuary and marine environment around

the Project area at some point in their life cycle.

5.1.2 Protected areas

Four significant protected areas are located in the Project region: Bunurong

Marine Park, Bunurong Marine National Park, Bunurong Coastal Reserve and

Kilcunda-Harmers Haven Coastal Reserve (shown in Figure 5-1).


Figure 5-1 Marine parks and coastal reserves near the Desalination Plant site


Bunurong Marine Park and Bunurong Marine National Park

Bunurong Marine National Park and Bunurong Marine Park protect 3 303

hectares of the Central Victoria Bioregion. They are managed under the

National Parks Act 1975 (Vic). All forms of extraction, including recreational and

commercial fishing and shellfish collection are prohibited in Bunurong Marine

National Park. Sections of these marine parks and adjacent coastal reserves

have been listed on the Register of the National Estate.

Bunurong Marine National Park is located 15 kilometres south-east of the Project

area. It extends from the mean high water mark along 5 kilometres of coastline

between the southernmost headland west of Oaks Beach and the headland at

the eastern end of Eagles Nest Beach, and offshore for approximately three

nautical miles (5.5 kilometres) to the limit of Victorian waters (Figure 5-1).

Bunurong Marine Park (1 203 hectares) complements Bunurong Marine National

Park as it protects two separate areas along 12 kilometres of coastline adjoining

the Bunurong Marine National Park from the mean high water mark to one

kilometre offshore.

Six marine ecological communities are present within the parks: sandy beaches,

intertidal reef platform, subtidal reef, subtidal soft sediments, seagrass and open

waters. Intertidal and subtidal reef communities are the most common habitat

type and incorporate many microhabitats.

Bunurong Marine National Park is significant in that at least 21 species of algae,

invertebrates and fish are thought to have their distributional limits in or near

the park. Additionally, a population of the rare Holothurian, Pentocnus bursatus, a Victorian marine invertebrate of conservation concern, has also been recorded

within the planning area at Cape Paterson (CEE 2008, Technical Appendix 31).

Bunurong Coastal Reserve

Bunurong Coastal Reserve (92.9 hectares) encompasses a coastal area

dominated by rugged sandstone cliffs, rocky headlands, intertidal rock platforms

and sandy areas. The coastal reserve protects a narrow strip of coast adjacent

to Bunurong Marine Park and Bunurong Marine National Park between the

eastern boundary of the Cape Paterson Foreshore Reserve at Undertow Bay in

the west and Wreck Creek in the east (Figure 5-1).


Kilcunda-Harmers Haven Coastal Reserve

A portion of the Kilcunda-Harmers Haven Coastal Reserve is also located

adjacent to Bunurong Marine Park (Figure 5-1). This reserve extends to

immediately offshore from the proposed Desalination Plant site.

5.2 Marine ecology

A simple conceptual model of the near-shore marine ecosystem in the Project

area is shown in Figure 5-2. Sunlight provides energy for planktonic plants

(phytoplankton) and seaweeds. Phytoplankton provide food for planktonic

animals (zooplankton), which provide food for small pelagic fish. These fish

provide food for larger fish, mammals and seabirds. Ocean currents move the

plankton and pelagic species follow their moving food.

Some of the planktonic material falls to the seabed (becoming detritus) where it

provides food for benthic (seabed) species. In reef habitats seaweeds and

microalgae provide food for grazing invertebrates and some fish. Seaweeds

(notably kelps) also provide habitat for a variety of reef species.


Figure 5-2 Conceptual model of marine community offshore from Wonthaggi

5.2.1 Reef communities

Most of the seabed in the Project area to 2.5 kilometres offshore comprises

rocky reef. The reef community is a kelp-characterised community (Phyllospora

and Ecklonia species) to approximately 28 metres depth, and a red macroalgal

and invertebrate community from 28 to 35 metres with increasing dominance

of invertebrates as water depth increases. The physical structure of the reef

contributes to the complexity and biodiversity of the reef community.

Biological relationships within the marine environment include beneficial

relationships, such as the ones in which kelps provide habitat for reef fish.

Other relationships are competitive such as when benthic macroalgae in the

community compete for space and shade each other.


The reef supports a wide range of predators, omnivores, herbivores, and

grazers (such as grazing sessile invertebrates). Some algae are consumed by

reef fish. There are also a number of invertebrates in the reef community:

seastars, crabs, lobsters and shrimps. Filter feeders include sessile species -

such as sponges, ascidians, bryozoans, some echinoderms, bivalves and fan

worms, and mobile species, which include small crustaceans such as mysids

and shrimps.

5.2.2 Planktonic-pelagic community

The planktonic and pelagic community is mobile. Plankton drift with water

currents and pelagic species may swim over long distances either following their

food, travelling along migration pathways or dispersing from the area they

occupied as juveniles. Many of the species in the marine ecosystem reproduce

with planktonic gametes or planktonic propagules. These planktonic components

may remain as plankton for minutes, days, weeks, months and even years,

depending on the species. Pelagic species include a wide range of mobile fish

and invertebrates that roam the near-shore or ocean waters.

Various species represent links in the pelagic food chain. Some fish such as

anchovies and pilchards eat plankton, while larger predatory fish such as

Australian Salmon and Barracouta eat the fish. Other animals including seabirds,

whales and sharks also interact in the pelagic community.

5.3 Benthic habitats

5.3.1 Intertidal habitat

Most of the intertidal habitat from Kilcunda to Coal Point comprises sandy

beaches with smaller patches of reef scattered along the coastline.


5.3.2 Intertidal sandy beach community

The biota of the intertidal sandy beaches of the Victorian coastline are generally

sparse assemblages of insects, crustaceans, polychaete worms and molluscs.

There is little available information on the sandy beach communities for the

Project area. The distribution of beach infaunal species follow a general pattern

along the Victorian coastline of insects restricted to higher shore levels,

polychaete worms found in lower shore levels, and crustaceans distributed at all

shore levels. However, many species change in abundance at different beach

heights depending on the time of year (CEE 2008 Technical Appendix 31).

5.3.3 Intertidal reef community

The South Gippsland coastline is scattered with intertidal reef platforms that are

composed of Cretaceous sandstones and mudstones and support a diverse array

of flora and faunal species. Intertidal communities generally exhibit a large

amount of spatial and temporal variation. The characteristics of the community

depend largely on the aspect and elevation of the reef and the effect of sand

movement. Numerous species of algae and invertebrates inhabit the intertidal

reef community.

Algae

The brown algae Hormosira banksii dominates the intertidal reefs of Bunurong

National Park and other reefs along the Victorian coast. The red algae Corallina officinalis, blue-green algae Symploca spp. and the green algae Ulva spp. are

also common on these reefs.

Invertebrates

The intertidal reefs of the Bunurong National Park and neighbouring reefs is

dominated by gastropod snails, including Austrolittorina unifasciata, Bembicium nanum and the limpets Siphonaria spp. The distribution and abundance of these

species is spatially and temporally variable.


5.3.4 Subtidal habitat

The subtidal habitats along the coastline from Point Grant to Coal Point

comprise an irregular mosaic of scattered reef and areas of soft sediments.

The general distribution of these habitats along the Project area is shown in

Figure 5-3.

Figure 5-3 Distribution of habitats offshore from the Project area

Source: CEE 2008

At the Project area, the seabed increases in depth relatively rapidly from the

shoreline over a distance of approximately 500 metres after which it slopes

gradually. The depth profile over this distance varies due to the presence of

sand bars along the beach.

Mobile sand communities

In the subtidal habitats of the Project area sand extends from the shoreline to a

depth of approximately 30 metres offshore. This area of sand is bordered by an

irregular boundary of reef. Larger areas of mobile sand extend through the

breaks in the reef. There is substantial and frequent movement of sand along

the coast and observations of the reef along the sand-reef boundaries indicate

a high degree of sand scour with bare rock at many locations.


Observations of the seabed in the Project area between September 2007 and

March 2008 revealed that the soft seabed is highly variable ranging from fine

sand with small ripples, to coarse gravel and shellgrit with substantial sand

waves. Some patches of soft seabed also contain rock rubble, and others areas

have a thin veneer of sand over rock. It is apparent that the soft sediments are

frequently mobilised.

Epibiota are very sparse on the mobile sands with only occasional sightings of

individual sponges attached to rubble or shell material. Although there is little

information available on the diversity and distribution of epibiota in the region

(central Bass Strait), the fauna of the sandy seabed of the region is generally

considered sparse and characterised by scallops and other large bivalve

molluscs, crabs, sea squirts, seapens, sponges and bryozoans.

No seagrass are found in the Project area. Due to the nature of the open,

wave-swept coastline at the Project area, it is unlikely that there are any

nearby, substantial seagrass beds.

The infaunal populations in mobile sands are highly spatially variable and

relatively short-lived. The range of sediment types along the coast contributes to

the patchy nature of the infaunal communities. Infaunal samples from along the

South Gippsland coastline, between Phillip Island and the Bunurong Marine

National Park, showed a high diversity of taxa dominated by polychaetes,

crustaceans and molluscs.

Mobile sand habitats similar to this mobile sand community in the Project area

are widely distributed along the coast from Griffiths Point to Coal Point, and are

well represented along the ocean coast of Victoria. The specific characteristics of

the associated biological community do vary somewhat according to a range of

physical, chemical and biological factors.

Reef communities

Reef occupies most of the seabed from approximately eight metres to 30 metres

at the Project area, extending 1.5 kilometres offshore. Reefs are grouped

by their bathymetry and structural characteristics into high, medium and low

relief reef.


High relief reef is characterized by topographic variations up to two metres with

substantial pinnacles, undercutting and dissection with crevices, which provide

a range of habitats in three dimensions. Medium relief reef is defined by

topographic variations up to one metre with substantial pinnacles, undercutting

and dissection with crevices, providing habitat in three dimensions. Low relief

reef has topographic variation up to 0.5 metres with little undercutting or

dissection and limited habitat in three dimensions.

A survey of the Project area subtidal reef communities was conducted in March

2008. A priority of the survey was to initially characterise the community over a

large area, including the Project area and reference areas. Diver-operated video

survey techniques and videos were used to provide permanent records of the

seabed community. The video recordings were analysed using a systematic

survey technique to identify marine species abundance and diversity.

From this survey, the biological character of the reef surface community

was characterised.

Algae

The kelps Phyllospora comosa and Ecklonia radiata dominate the reefs

in the Project area. Ecklonia radiata is found on high and low profile reefs.

The abundance of Phyllospora is generally higher in the shallow areas.

The reefs offshore from Lower Powlett Road have a high proportion of sand and

associated red algal turf on the low relief reef. Brown algae at the Project area

include Cystophora, Sargassum, Carpoglossum and Zonaria.

Red algae are present on the reefs surveyed in the Project area. They dominate

in areas where there is a break in the canopy of the kelp. Encrusting coralline

algae dominate the reef surface beneath the heavier canopies of kelps.

Filamentous red algae and coralline turfs are common where the reef is partially

covered with sand. The red algal flora of southern Australia is highly diverse and

the red algal flora of the Project area is likely to be diverse and generally similar

to that in the Bunurong area.


In general, Central Victorian ocean reefs between 7 metres and 16 metres are

dominated by brown algae including Phyllospora and Ecklonia (Figure 5-4).

The green alga Caulerpa sp. is present in small patches amongst the brown and

red algae. There are small areas of bare rock on the reef where sand movement

and scour remove or prevent the growth of algae. In general, between 16

metres and 27 metres water depth Phyllospora is less prevalent and the algal

community is dominated by the brown algae Ecklonia and red algae species.

In depths greater than 30 metres, where light is limiting, the reef community is

dominated by red algae, sponges and ascidians (sea squirts) such as Pyura sp.

Figure 5-4 Reef community changes with water depth

0

1

2

3

4

5

6

0 5 10 15 20 25 30 35 40

Depth, m

Ascidians

Sponges

Red algae

Brown algae

Ecklonia

Phyllospora

The dominance by Phyllospora and Ecklonia in the reef surface community at

the Project area between Coal Point and Kilcunda is not found at the reef

surface community in the Bunurong area to the east of Coal Point, where these

species are absent or present in very low abundance. The pattern of

predominance by Phyllospora and Ecklonia at exposed reefs along the central

and western Victorian coastline is well known, and Harmers Haven

(approximately 2.5 kilometres south-east of Coal Point) is likely to be the

approximate geographic boundary between the Phyllospora-Ecklonia kelp

community found in the Project area and the Cystophora-Sargassum community

of the Bunurong reefs. The difference between the Bunurong reefs and those

elsewhere is likely to be a reflection of the lower wave energy along the

Bunurong coast east of Coal Point (CEE 2008, Technical Appendix 31).


Invertebrates

The abundance of invertebrates is strongly linked to reef topography, with

higher abundance and diversity in areas of high relief reef and lower diversity

in areas of low relief reef. The high relief reef at the Project area has an

abundance of sessile invertebrate fauna including sponges, ascidians,

bryozoans, gorgonians and hydroids attached to the vertical surfaces of the

crevices and overhangs. Abalone, snails and sea urchins shelter in the crevices.

The ascidian, Herdmania momus, is found individually or in small clusters on the

reef surface. Various individual seastars and sea urchins occur in the reef with

occasional abalone and sponges. However, these invertebrates are very sparsely

distributed outside the cover of the macroalgae or away from the protection of

crevices and overhanging ledges and few were detected in the video analysis.

Fish

Reef fish are generally sparse in the Project area, except near Coal Point where

the reef structure is relatively complex. Blue-throated Wrasse are found

throughout the Project area, although they are very sparse. Blue-throated

Wrasse are the most common reef fish in this area and along the Victorian coast

in general. Blue-throated Wrasse have limited home ranges and individuals are

relatively restricted to particular reefs. Adult Blue-throated Wrasse have low

natural mortality, and population dynamics are likely to be influenced by larval

dispersal and juvenile mortality (CEE 2008, Technical Appendix 31). They are

carnivorous fish with varied diets and, based on observations of similar species,

they are likely to play an important role in reef ecology.

Other fish found in the Project area include Magpie Morwong Cheilodactylus nigripes, various leatherjackets (yellow-striped, six-spine, rough), Scalyfin Parma victoriae, Common Bullseye Pempheris multiradiata, Senator Wrasse Pictilabrus laticlavius and Sea Sweep Scorpis aequipinnis. Generally, the reef fish

community at the Project area is similar to other reefs in the region. Table 5-1

shows fish and cephalopods recorded in surveys around subtidal rocky reefs in

the Bunurong Marine National Park.


The general abundance and diversity of reef fish is likely to be linked to

reef topography, with higher abundance and diversity in areas of complex

reef habitat and lower diversity in areas of low relief reef with little three-

dimensional structure.

Table 5-1 Fish and Cephalopods recorded in surveys of subtidal rocky reefs in the Bunurong Marine National Park

Common name Scientific name Habitat Distribution

Cephalopods

Australian Giant

Cuttlefish

Sepia apama Occurs on rocky reefs, seagrass beds, and areas of

mud and sand

Endemic to Australian

waters

Mobile Sharks and Rays

Draughtboard

Shark

Cephaloscyllium laticeps

Continental shelf from close inshore to deeper waters Eastern Indian Ocean

Smooth Stingray Dasyatis brevicaudata

Offshore, on sandy bottoms, in bays, harbours, and

near rocky reefs

Indo-west Pacific

Banded

Wobbegong

Orectolobus ornatus Inshore waters on algal-covered rocky areas and coral

reef

Western Pacific

Varied

Carpetshark

Parascyllium variolatum

Continental shelf; ecology unknown but may occur in a

variety of habitats

Endemic to Australia

Sparsely-spotted

Stingaree

Urolophus paucimaculatus

Continental shelf Endemic to Australia

Mobile Bony Fishes

Toothbrush

Leatherjacket

Acanthaluteres vittiger

Seagrass beds and rocky reefs Throughout southern

Australia

Western Blue

Groper

Achoerodus gouldii Continental shelf Across southern

Australia

Southern Seacarp Aplodactylus arctidens

Weedy reef slopes Indo-Pacific

Shaws Cowfish Aracana aurita Rocky reefs Eastern Indian Ocean

Ornate Cowfish Aracana ornata Shallow waters Southern Australia

Australian Herring Arripis georgiana Coastal and estuarine Across southern

Australia




Australian Mado Atypichthys strigatus

Coastal and estuarine Indo-west Pacific

Magpie Morwong Cheilodactylus nigripes

Rocky reefs Indo-west Pacific

Banded Morwong Cheilodactylus spectabilis

Shallow reefs South-west Pacific

Dusky Morwong Dactylophora nigricans

Seagrass beds and rocky outcrops Eastern Indian Ocean

Long-finned Pike Dinolestes lewini Marine Endemic to southern

Australia

Globefish Diodon nicthemerus Shallow bays Southern Australia

Castelnau's

Wrasse

Dotalabrus aurantiacus

Demersal Southern Australia

Old Wife Enoplosus armatus Inshore and offshore rocky reefs and seagrass beds Endemic to Australia

Gunn's

Leatherjacket

Eubalichthys gunnii Coastal reefs Southern Australia

Luderick Girella tricuspidata Estuaries, rocky reefs and coastal areas Western Pacific

Zebrafish Girella zebra Reef and marine Indo-Pacific

Johnston's

Weedfish

Heteroclinus johnstoni

Low reefs Indo-Pacific

Sharp-nose

Weedfish

Heteroclinus tristis Shallow, low reef Indo-Pacific

Brown-striped

Leatherjacket

Meuschenia australis

Reefs Southern Australia

Yellow-striped

Leatherjacket

Meuschenia flavolineata

Reefs Eastern Indian Ocean

Six-spine

Leatherjackets

Meuschenia freycineti

Demersal Eastern Indian Ocean

Blue-lined

Leatherjacket

Meuschenia galii Reefs Eastern Indian Ocean




Horse-shoe

Leatherjacket

Meuschenia hippocrepis

Offshore reefs Southern Australia

Common Threefin Norfolkia clarkei Intertidal rocky pools, estuaries Eastern Indian Ocean

Purple Wrasse Notolabrus fucicola Rocky reefs Eastern Indian Ocean

and south-west Pacific

Blue-throated

Wrasse

Notolabrus tetricus Rocky reefs South-west Pacific

Rainbow Cale Odax acroptilus Rocky reefs Eastern Indian Ocean

Herring Cale Odax cyanomelas High energy surf zones Eastern Indian Ocean

Maori Wrasse Ophthalmolepis lineolata

Coastal bays and offshore reefs Southern Australia

Southern Silver

Belly

Parequula melbournensis

Southern shelf Southern Australia

White-ear Scalyfin Parma microlepis Rocky reefs South-eastern

Australia

Victorian Scalyfin Parma victoriae Rocky reefs Eastern Indian Ocean

Common Bullseye Pempheris multiradiata

Demersal Indo-west Pacific

Long-snouted

Boarfish

Pentaceropsis recurvirostris

Reefs on continental shelf Eastern Indian Ocean

Senator Wrasse Pictilabrus laticlavius

Rocky reef-algae habitats Eastern Indian Ocean

Crimson-banded

Wrasse

Pseudolabrus psittaculus

Reef-associated, marine Southern Australia

Southern Bastard

Codling

Pseudophycis barbata

Hard bottom, over exposed reef South-west Pacific

Ocean

Rough

Leatherjacket

Scobinichthys granulatus

Seagrass beds and rocky reefs Eastern Indian Ocean

Sea Sweep Scorpis aequipinnis Offshore and deepwater reefs Australian waters




Silver Sweep Scorpis lineolata Coastal reefs as adults; estuaries and rocky pools for

small juveniles

South-west Pacific

Common

Warehou

Seriolella brama Adults inhabit continental shelf and slope waters.

Juveniles sometimes enter estuaries

South-west Pacific

King George

Whiting

Sillaginodes punctata

Inhabit shallow inner continental shelf waters, mainly

in association with seagrasses as juveniles; associated

with exposed waters and reef as adults

Southern Australia

Snook (Australian

barracuda)

Sphyraena novaehollandiae

Pelagic Indo-Pacific

Smooth Toadfish Tetractenos glaber Coastal bays on sandy flats Indo-west Pacific

Moonlighter Tilodon sexfasciatus Juveniles in estuaries; adults in more open waters on

offshore rocky reefs

Southern Australia

Common Jack

Mackerel

Trachurus declivis Benthopelagic South-west Pacific

Blue Spotted

Goatfish

Upeneichthys vlamingii

Shallow, sandy coastal waters and rocky estuaries Southern Australia

Cryptic fishes

Warty Prowfish Aetapcus maculatus Shallow coastal waters Eastern Indian Ocean

Thornfish Bovichtus angustifrons

Inhabits shallow rocky reefs Indo-west Pacific

Red Velvetfish Gnathanacanthus goetzii

Inshore Endemic to Australia

Reef Ocean Perch Helicolenus percoides

Continental shelf and slope South-west Pacific

Source: CEE 2008

5.4 Pelagic habitats

The community structure in the pelagic habitat consists of plankton, fish and

larger mammals such as whales and dolphins.


5.4.1 Plankton

Plankton is made up of animals and plants that either float passively in the

water, or possess limited powers of swimming, and are carried from place to

place by the ocean currents. Plankton plays an important role in the marine food

chain and is food for a range of animals from barnacles and sea squirts to large

fish and whales. Plankton can be generalised into three groups:

• phytoplankton

• zooplankton

• eggs and larvae.

The distribution of plankton within Bass Strait is spatially and temporally

variable. This is because plankton are influenced by regional current patterns

within Bass Strait, which fluctuate during the year. Influential current patterns

include the East Australia Current, west to east flows from Bass Strait and

Southern Ocean masses (CEE 2008, Technical Appendix 31).

Phytoplankton

Phytoplankton are photosynthetic organisms that spend either part or all of their

lifecycle drifting with the ocean currents. Phytoplankton biomass is greatest at

the extremities of the Bass Strait (particularly in the north-east) where water is

shallow and nutrients are highest. In general, the abundance of phytoplankton

within Bass Strait is considered to be relatively low compared to other systems

such as those studied in New South Wales.

Zooplankton

Although the abundance of phytoplankton within Bass Strait is considered low,

zooplankton biomass is higher within Bass Strait than over the continental shelf.

The vertical migration of zooplankton has been highlighted as an important

adaptive feature that allows zooplankton to maintain their horizontal distribution

within a body of water. This appears to only be important for populations found

within bays, and this feature is not commonly seen in zooplankton populations

from open coast areas such as Bass Strait.


Of the Bass Strait zooplankton population, the distribution of one of the Little

Penguins prey species, Krill Nyctiphanes australis, has been well studied. During

the day, Krill occur within a band between five and 10 metres deep on or near

the seabed (CEE 2008, Technical Appendix 31).

Eggs and larvae

Marine plants and animals reproduce in a wide variety of ways. Generally

reproductive stages are:

• fertilisation or asexual reproduction

• dispersal of propagules

• settlement of propagules or larvae to the preferred habitat (if benthic)

• development into adult form (metamorphosis).

The egg and larval stages of many marine species live solely in the water

column and drift in the water column for periods of time before they return to

their adult habitat. These planktonic egg and larval stages allows offspring to

disperse away from adult habitat. Larval dispersal is also an important process

via which replenishment occurs.

The characteristics and duration of the planktonic life stages vary between

species. The length of time planktonic life stages remain in the water and their

position in the water column is one factor determining the distance to which

offspring disperse. Some planktonic life stages drift with currents and have the

ability to be widely dispersed. Others are released into the water but remain

within the confines of the local habitat where they are sheltered from dispersing

currents, and many settle back to the seabed close to where they originated.

Others have very short planktonic periods or are motile and stay very close

to the seabed and may select habitat close to where they originated.

Planktonic stages of some marine species known in the Project area are

shown in Table 5-2.


Table 5-2 Planktonic stages of some local marine species

Name Species

Larval stages Duration of larval stage

Fish

Gametes Hours

Fertilised Eggs Days

Flathead

Platycephalus spp

Larval fish 30-90 days

Gametes Hours

Fertilised Eggs 2 days

Barracouta

Thyrites atun

Larval fish Months

Gametes Hours

Fertilised Eggs Hours to days

Australian Anchovy

Engraulis australis

Larval Fish 30 days

Gametes Hours


Australian Pilchard

Sardinops sagax

Larval Fish 30 days

Gametes Hours


Blue-throat Wrasse

Notolabrus tetricus

Larval fish 7 days

Invertebrates

Gametes Hours


Blacklip Abalone

Haliotis rubra

Trochophore Larva 4 days

Gametes Hours


Greenlip Abalone

Haliotis laevigata

Trochophore Larva 4 days

Sea Urchin

Heliocidaris sp Gametes Total larval period is 3.5 to 4

days

Southern Rock Lobster

Jasus edwardsii Multiple larva stages 12 – 24 months


Name Species

Larval stages Duration of larval stage

Seaweed

Gametes Hours Leather Kelp

Ecklonia radiata Propagules (zoospores) 1 hour

Gametes 12 hours

Zygote 12 hours

Cray Weed

Phyllospora comosa

Propagules Hours

Gametes/zygote 12 hours Neptunes Necklace

Hormosira banksii Propagules Hours to days

Gametes Hours Rock Weed

Sargassum sp Propagules Less than 40 days

Larval dispersal is an important component of the process of population

replenishment of the population. Natural mortality in the larval stage can

be very high and some populations of clams and barnacles require only

0.0001 per cent to 0.00005 per cent survival of larvae to maintain the adult

populations (CEE 2008, Technical Appendix 31). Generally, natural survival in

the larval stage is less than one per cent.

The dispersal characteristics of planktonic life stages can be divided into

four categories.

• no planktonic larval duration

• very short planktonic larval duration (minutes to two days)

• short planktonic larval duration (days to weeks)

• long larval periods (> 30 days) with isolated spawning area, defined

dispersion pathway or widespread propagules release.


Very short larval duration

Many species have very short planktonic life stages ranging from minutes to a

few days. These species generally are released and settle within the local area.

The kelp Ecklonia radiata has a complex life history, and the plankton life stage

of this species may settle back to the seabed within one hour of release. Other

seaweeds also have short planktonic phases in their reproduction cycle. Many

small sessile invertebrates such as bryozoans, sponges and ascidians have short

larval periods of only hours. Some of these larvae may move across the seabed

and do not mix with the water column.

Short larval duration

Many reef species have short planktonic periods of days to weeks and may be

dispersed in the order of hundreds of meters to kilometres, depending on local

currents and larval behaviour. Abalone and Blue-throated Wrasse have short

planktonic larval periods. Abalone larvae have the ability to be widely dispersed

but most remain within the local area and settle to the reef seabed close to their

parents. Wrasse also have relatively short planktonic periods of approximately

one week and may also have restricted dispersal.

Long larval duration

Some marine species have larval periods extending to several months.

These larvae may disperse with prevailing currents to suitable areas where

they will settle. King George Whiting are an example of species with an

isolated spawning area, defined dispersion pathway and a long larval period.

This species breeds at the South Australia-Victoria border. Whiting larvae remain

in the water column for up to three months travelling with the prevailing

currents along the western and central Victorian coastline. They have a dispersal

range of hundreds of kilometres and are known to settle in Port Phillip Bay,

Western Port and Corner Inlet.

Some marine species are widespread and have even longer larval periods of

months to years. These larvae can be dispersed over wide geographic areas.

They may either settle on appropriate seabed habitat or, in the case of pelagic

species, metamorphose into adults in the water column.


Rock lobster larvae are released into the water column and remain as plankton

for up to two years. These larvae can be widely dispersed over hundreds of

kilometres throughout waters offshore from Tasmania, south-eastern South

Australia and western and eastern Victoria. Rock lobster larval production and

settlement between Lorne and Wilsons Promontory, including the Project area,

is very low. Recruitment of lobster in the Project area may be due to individual

episodes of settlement or migration of young adults. High abundances of

juvenile rock lobsters may occur at Flinders and Kilcunda from time to time.

Two species that also fit this larvae category—anchovy and pilchards—have

larval durations of approximately 30 days. These species are important food

sources for large pelagic fish, the Little Penguin and other marine animals.

Anchovy eggs and larvae

Adult anchovy spawn throughout the coast and continental shelf waters. In

south Australian waters, spawning may occur over the entire year. Bays and

estuaries are especially important spawning areas (e.g. Western Port and the

Gippsland Lakes in Victoria).

Egg and larval sampling in Western Port and Bass Strait around the Project area

has been conducted for 10 months. It has informed the impact assessment

(Chapter 8 of this Volume). In general, surveys of anchovy eggs and larvae in

South Australia and Victoria indicate:

• a high degree of spatial and interannual variation in egg and larval density

• anchovy spawning may be widespread across the continental shelf and egg

densities may be widespread across the shelf and near-shore waters

• anchovy egg and larval densities in Western Port are low relative to Port

Phillip, Gippsland Lakes and the South Australian gulfs

• while adult anchovy may spawn at low levels throughout the year in

offshore waters, they appear to migrate into near-shore waters and bays

for peak spawning in warmer months

• anchovy larval densities appear greatest near-shore and in certain bays

• no significant difference in the quantity of anchovy eggs through the

water column.


Large concentrations of anchovy eggs were found in the area offshore from the

Project area during the September survey, as shown in Table 5-3. This is likely

to represent a wider distribution of anchovy eggs extending at least offshore

from Phillip Island.

Table 5-3 Sampling numbers of anchovy and other fish eggs collected in 2007.

Anchovy eggs Other fish eggs

Month Western Port Bass Strait Western

Port Bass Strait

September 33 3 213 1 539 3 732

October 5 676 906 2 046

November 0 128 1 018 1 655

December 6 621 682 4 995

Pilchard eggs and larvae

Pilchard eggs have been collected in the Project area around Cape Schanck and

near the entrance to Western Port between November 2007 and January 2008,

while pilchard larvae have been collected in inshore waters off Cape Schanck

from December 2007 to February 2008. In recent sampling for the Project,

pilchard larvae represented 0.2 per cent of the total fish larvae recorded.

Surveys indicated that pilchard larvae were absent from Western Port and Bass

Strait in September and December 2007. Sampling in Western Port found the

majority of pilchard larvae near the sea bottom.


King George Whiting eggs and larvae

King George Whiting does not appear to spawn in central Victorian waters.

Spawning occurs from May to July, most likely from far western Victoria through

South Australia. Post-larvae of approximately 15-20 millimetres length enter Port

Phillip Bay, Western Port and Corner Inlet from September to November each

year. Fish egg and larval sampling for the Project did not find King George

Whiting larvae in ocean water samples. Only one larva was found in the

samples from the site in the eastern entrance to Western Port. Although larvae

of this species were not found, they are likely to pass the Project area and they

are likely to be mature (competent) large larvae that are sparsely distributed in

the waters in the area. Modelling suggests that these larvae are advected east

along the coast from the spawning grounds and would occasionally be present

in the Project area over the spring period. Post-larvae have been collected in

seagrass beds in the Rhyll area of Western Port.

No planktonic larval period

Many pipefish, including the weedy and leafy seadragons, do not have

planktonic larval periods. Female pipefish deposit eggs directly into egg pouches

in the abdomen of the male. Males then brood the eggs until they hatch into

small, fully formed pipefish or seadragons. Marine species that do not have a

larval period tend to have dispersal extents in the order of tens of metres,

depending on the mobility of the small juvenile organisms.

5.4.2 Fish

Fish in the Project area can be categorised as pelagic and reef fish. Pelagic

fish are described below while details of commercial fisheries operating in the

Project area are presented in Section 6.1.

An extensive survey of pelagic fish and cephalopods (squid and octopus) has

been conducted within a 20-kilometre radius of the Phillip Island Penguin

Reserve in Bass Strait. Species found in the survey that are relevant to the

Project area are shown in Table 5-4.


Only four species occur in mid waters: the Blue Grenadier Macruronus novaezelendiae, the Slender Bullseye Parapriacanthus elongatus, the Rosy Perch

Callanthias allporti and the Suckerfish Remora remora. Most other species occur

in both mid-water and near the seafloor. The most abundant fish are the

Australian Anchovy Engraulis australis, and the Pilchard Sardinops neopilchardus, followed by the Barracouta Thyrsites atun. The anchovy and

pilchard are patchily distributed in mid-water or near the seabed (CEE 2008,

Technical Appendix 31).

Table 5-4 Pelagic fish and cephalopods found in mid-water and demersal habitats in Bass Strait and Western Port


Anchovy Engraulis australis

Mostly inshore, although older

individuals tend to move out to sea in

winter

South-west Pacific

Barracouta Thyrsites atun Continental shelf; benthopelagic South-west Atlantic and south-east

Pacific

Blue Grenadier Macruronus novaezelandiae

Benthopelagic; commonly in large

estuaries and bays

New Zealand and southern Australia

Boarfish, Black-

spotted

Zanclistius elevatus

Demersal; continental shelf and slope South Pacific

Boarfish, Long-

snouted

Pentaceropsis recurvirostris

Reef-associated on continental shelf Eastern Indian Ocean

Bullseye, Slender Parapriacanthus elongatus

Demeral; schooling near rocky reefs Indo-west Pacific

Cod, Bearded

Rock

Pseudophycis barbata

Hard bottom over exposed rocky reefs South-west Pacific

Cod, Red Pseudophycis bachus

Demersal over soft, sandy and rocky

bottoms

South-west Pacific

Cowfish, Ornate Aracana ornata Shallow waters Australia

Cowfish, Shaw’s Aracana aurita Continental shelf; found in rocky reefs Eastern Indian Ocean

Dory, Silver Cyttus australis Continental shelf and slope Eastern Indian Ocean

Eel, Conger Leptocephalus wilsoni

Reef-associated in coastal waters and

estuaries

Western Indian Ocean



Flathead, Rock Platycephalus laevigatus

Inshore and over reefs Endemic to southern Australia

Flathead, Sand Platycephalus bassensis

Inland coastal waters from shallow bays

to inlets

Endemic to Australia

Flathead, Tiger Platycephalus richardsoni

Inshore waters over the continental

shelf and sometimes entering coastal

bays

Only known from Coffs Harbour in

northern NSW to Portland in Victoria,

including Bass Strait and Tasmania.

Flathead, Toothy Platycephalus aurimaculatus

Sandy bays and coastal waters Restricted to southern Australia

Flounder,

Greenback

Rhombosolea tapirina

Found on silty sand substrata from

estuaries to inshore waters

Eastern Indian Ocean and south-west

Pacific

Flounder, Long-

snouted

Ammotretis rostratus

Sandy regions of bays and offshore

areas

Southern Australia

Gurnard perch,

Red

Helicolenus percoides

Continental shelf and slope South-west Pacific

Gurnard, Butterfly Lepidotrigla vanessa

Coastal marine waters Australian waters

Gurnard, Cocky Lepidotrigla modesta

Coastal waters Southern Australia

Gurnard, Round-

snouted

Lepidotrigla mulhalli

Sandy bottoms in coastal marine waters South-west Pacific

Gurnard, Sharp-

beaked

Pterygotrigla polyommata

Adults found on the continental shelf;

juveniles enter bays and estuaries

South-west Pacific

Source: CEE 2008

A number of fish species of note discussed below are either species of interest

for the region or are protected under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC) or Flora and Fauna Guarantee Act 1988 (FFG) (discussed further in section 5.6).


Great White Shark

The Great White Shark is a very large shark and occurs in all oceans of the

world, including in the Bass Strait and the Project area. Surfers, abalone divers,

commercial and recreational fishers have observed Great White Sharks in the

Project area from time to time. These large sharks are highly mobile and have

large individual geographic ranges. Individuals appear to remain resident in one

locality only for periods of days or rarely weeks according to observations from

fishermen, divers and marine scientists. The breeding characteristics of sharks

are not known with only two pregnant females recorded in contemporary times

(CEE 2008, Technical Appendix 31).

Grey Nurse Shark

The east coast population of the Grey Nurse Shark is listed as critically

endangered under the EPBC Act (the west coast population is listed as

vulnerable). There are no recent confirmed records of Grey Nurse Sharks in

Victoria south of Mallacoota. The distribution of this shark (western and eastern

populations) in Australia is considered confined to Western Australia, southern

Queensland and the entire New South Wales coast. Grey Nurse Sharks are

therefore unlikely to be found in the central Bass Strait region or in the region

of the Project.


Australian Grayling

The Australian Grayling is a small (300 millimetres long) freshwater fish that

has larval and juvenile stages in the marine environment. It is EPBC-listed as

vulnerable and FFG-listed. Its population has reduced substantially over the past

100 years. The current distribution is patchy over its former range from the

Grose River west of Sydney throughout New South Wales, Victoria, eastern

South Australia, and Tasmania and around King Island in Bass Strait. In Victoria,

the Australian Grayling is known to occur in the Hopkins River, Barham River

and larger populations may occur in rivers in eastern Victoria such as the Tambo

River. Adult Australian Graylings occur in the freshwater reaches of the Yarra

River. The degree of mixing between these populations through larval and

juvenile dispersal is not known. It is unlikely that the marine environment in

the Project area or the nearby Powlett River forms significant habitat for the

Australian Grayling (CEE 2008, Technical Appendix 31 and Biosis Research 20083


Southern Bluefin Tuna

The Southern Bluefin Tuna is widely distributed in southern oceans from New

Zealand to southern Africa and into the South Atlantic Ocean. It is the basis of

a valuable fishing industry. Southern Bluefin Tuna prefer deep ocean waters or

the productive waters of the continental slope. Therefore, in Victoria, they are

only found in western and eastern Victoria where the continental shelf is

narrow. The Southern Bluefin Tuna is unlikely to be found in central Bass Strait

or in the Project area.

Syngnathids

Syngnathids (seahorses, seadragons and pipefish) occur in a wide range of

habitats. Syngnathids are not endangered, and protection under the Fisheries

Act may be to control their collection for the aquarium trade and collection for

traditional medicines.


Very little is known about some species, while other species such as the Leafy

and Weedy Seadragons are immediately recognisable and have attracted much

interest and study. Many pipefish, including the weedy and leafy seadragons,

do not have planktonic larval periods. The Weedy Seadragon Phyllopteryx taeniolatus is Victoria’s state marine emblem and is commonly distributed in a

variety of habitats along Victoria’s open coastline.

Australian anchovy

Australian Anchovy (Engraulis australis) are known to occur in the Project area,

although commercial fishing operators in the area do not target them. They are

important prey for Little Penguins and other marine predators.

Anchovy are widely distributed along the Australian coastline south of the Tropic

of Capricorn. Adult anchovy live for approximately five years and their habitat

ranges from bays and near-shore waters to offshore ocean waters over the

continental shelf.

Near-shore coastal waters of Victoria, as well as bays and inlets, are important

for spawning of anchovy (and pilchards) (discussed in section 5.4.1). In South

Australian waters, spawning may occur over the entire year with higher rates of

spawning from late spring to autumn, peaking from January to March.

Pilchard

Pilchards (Sardinops neopilchardus) are important prey for large pelagic fish,

penguins and other marine animals. They have been actively fished in southern

Australia. Very little is known about the spawning areas and season for Pilchard

in Victorian waters. Most of Victoria’s Pilchard fishery occurs in Port Phillip Bay.

Research indicates that, in general, Pilchards do not spawn within Port Phillip

Bay, but the bay is used as a nursery area. Pilchards may spawn mainly in shelf

waters outside enclosed bays. Pilchard numbers in general are low as a

consequence of a disease episode in the 1990s (CEE 2008, Technical

Appendix 31).


5.5 Marine mammals, reptile and birds

There are 14 mammals, one marine reptile and 31 marine bird species that

are known to either inhabit the Project area or surrounding Victorian waters.

Some of these species are protected by legislation including the EPBC Act and

the FFG Act as discussed in more detail in the following section (section 5.6)

5.5.1 Whales and dolphins

There are 10 species of whale and dolphin that are known to either inhabit the

Project area or surrounding Victorian waters (Table 5-5). The Southern Right

Whale is the only species that has been observed within five kilometres of the

Project area (Biosis Research 20082, Technical Appendix 13). Seven whale

species are protected under the EPBC Act, and three of these species are also

listed under the FFG Act (discussed further in section 5.6).

Table 5-5 Whale and dolphin species known to inhabit the Project area or surrounding Victorian waters

Common name Scientific name Recorded in Project area EPBC FFG

Killer Whale Orcinus orca - Migratory -

Humpback Whale Megaptera novaeangliae

- Vulnerable and Migratory Listed

Blue Whale Balaeonoptera musculus

- Endangered and Migratory Listed

Southern Right

Whale

Eubalaena australis

Endangered and Migratory Listed

Bryde’s Whale Balaenoptera edeni - Migratory -

Pygmy Right

Whale

Caperea marginate - Migratory -

Long-finned Pilot

Whale

Globicephala melas - - -

Sperm Whale Physeter macrocephalus

- Migratory -


Common name Scientific name Recorded in Project area EPBC FFG

Common Dolphin Delphinus delphis - - -

Bottlenose

Dolphin

Tursiops truncatus - - -

Killer Whale

The Killer Whale is listed as a migratory species under the EPBC Act.

This species is likely to routinely utilise or pass through the Project area

(Biosis Research 20082, Technical Appendix 13).

Humpback Whale

The Humpback Whales is a migratory species. The species is listed as vulnerable

in the EPBC Act and it is also listed in the FFG Act. Humpback Whales are large

whales growing to approximately 18 metres in length and have a worldwide

distribution.

Humpback Whales feed on krill and feeding generally occurs in Southern Ocean

waters. The majority of Humpback Whales in Australian waters migrate north to

tropical calving grounds during June to August. They then move south to the

Southern Ocean feeding areas during September to November.

Some whales from the eastern Australia migratory population travel along the

eastern coast of Tasmania and to the east of Victoria. Some individuals may

enter Bass Strait, but most of those that do appear to remain well offshore

when passing Victoria. Although it is possible that individuals may occasionally

move into the Project area, the central Bass Strait area, including the Project

area, is generally outside the migratory path of Humpback Whales, and this area

is not a feeding, breeding, or calving area for this species (Biosis Research



Blue Whale

The Blue Whales is a migratory species, and is also listed as endangered

in the EPBC Act and listed in the FFG Act. Blue Whales are the largest of all

whale species growing to 33 metres in length (average size of 25 metres).

The southern Australian population of Blue Whales is relatively small, but is still

considered to be an important component of the worldwide population as

globally this species has significantly declined in numbers as a result of whaling

prior to the 1960s.

Studies indicate that there is a population of Blue Whales that is resident

during the summer period in waters off South Australia and western Victoria.

The migration path of this population has not been determined. The whales may

migrate eastward and up the east Australian coast or westward to Western

Australia. Some individuals may pass through the central Bass Strait during

autumn and spring migrations to tropical areas, and it is possible that individuals

may pass through the Project area. However, it is most common for this species

to use deep waters at a considerable distance offshore from the coastline, and it

is considered unlikely that individuals will occur in the Project area (Biosis

Research 20082, Technical Appendix 13).

Southern Right Whale

The Southern Right Whales is a migratory species and is also listed as

endangered on the EPBC Act and listed on the FFG Act. Southern Right Whales

are large whales measuring up to 17.5 metres in length. They migrate each year

in winter to calve and mate in warmer waters off the southern Australian coast.

The total Australian population of Southern Right Whales is estimated to be

around 1 500 individuals. Whale sightings along the Victorian coast have

increased significantly in recent times, but the trend has not been quantified.

The number of whales visiting Victoria is a very small fraction of the Australian

population that spends winters along the coasts of South Australia and

Western Australia.


In Victoria, pregnant females generally arrive in May to June and depart with

their calves in October to November. Females with young calves may be found

anywhere along the coast from Gabo Island in the east to Cape Bridgewater in

the west, but most sightings are west of Port Phillip Bay. Southern Right Whales

are encountered sporadically in Bass Strait, but they are more frequently sighted

in western Bass Strait where they are known to calve. They are also

intermittently encountered in central Bass Strait. This species has been observed

in the Project area but the area is not a particularly important habitat for this

species (Biosis Research 20082, Technical Appendix 13).

Bryde’s Whale

The Bryde’s Whale is a migratory species that is protected under the EPBC Act.

It has been reported in Victorian waters on fewer than five occasions, and it is

not expected to use the Project area (Biosis Research 20082, Technical

Appendix 13).

Pygmy Right Whale

The Pygmy Right Whale is a migratory species that is protected under the EPBC

Act. It has a circumpolar range and inhabits temperate to subantarctic oceans.

It is very rarely observed in Victorian waters. This species is usually observed in

deep oceanic waters and is rarely seen in near-shore coastal areas; it is highly

unlikely to occur in the Project area (Biosis Research 20082, Technical

Appendix 13).

Long-finned Pilot Whale

This species is known to inhabit Victorian waters, and may utilise or pass

through the Project area. This species is not protected under either the EPBC or

FFG Acts (Biosis Research 20082, Technical Appendix 13).


Sperm Whale

The Sperm Whale is one of the migratory species listed under the EPBC Act.

Stranded specimens of this species have been recorded locally; however,

Victorian waters offer no suitable habitat for this species, and individuals that

may move into Bass Strait by accident do not remain in the area for long (Biosis


Common Dolphin

This species is likely to routinely utilise or pass through the Project area. The

Common Dolphin is not protected under either the EPBC or FFG Acts (Biosis


Bottlenose Dolphin

Bottlenose Dolphins are common in Victorian waters. This species is likely to

routinely utilise or pass through the Project area. The Bottlenose Dolphin is not

protected under either the EPBC or FFG Acts (Biosis Research 20082, Technical

Appendix 13).

5.5.2 Seals and sea lions

Four species of seals and sea lions are known to inhabit Victorian waters (Table

5-6). The Southern Elephant Seal and Australian Sea Lion are protected under

the EPBC Act (listed as vulnerable). The Australian Fur Seal, New Zealand Fur

Seal and the Australian Sea Lion may inhabit the Project area (Biosis Research



Table 5-6 Seal species protected under the EPBC Act or known to inhabit Victorian waters

Common name Scientific name Recorded in Project area EPBC

Southern Elephant Seal Mirounga leonina Infrequent visitor Vulnerable

Australian Fur Seal Arctocephalus pusillus doriferus

-

New Zealand Fur Seal Arctocephalus fosteri - -

Australian Sea Lion Neophoca cinerea - Vulnerable

Southern Elephant Seal

The Southern Elephant Seal is protected under the EPBC Act. This species

has a circumpolar distribution and are known to breed on subantarctic islands.

They travel up to several thousand kilometres to reach feeding areas.

The Southern Elephant Seal has been documented within five kilometres

of the Project area from a single sighting in 1996, but this species is recorded

infrequently along the Victorian coast and it is considered unlikely to occur in

the Project area (Biosis Research 20082, Technical Appendix 13).

Australian Fur Seal

The Australian Fur Seal is the most common seal species to inhabit Victorian

waters and colonies are found throughout the entire Bass Strait. The main food

sources of the Australian Fur Seal are schooling fish and squid, including jack

mackerel, barracouta and also non-schooling species such as leatherjackets

and octopus.

The closest known Australian Fur Seal breeding colony to the Project area is at

Seal Rocks at Phillip Island. This colony is located approximately 25 kilometres

from the Project area. Satellite tracking of Australian Fur Seals from the Phillip

Island colony has demonstrated that some adult females and juvenile animals

have visited the Project region (Biosis Research 20082, Technical Appendix 13),

but that visitation, generally by the Phillip Island seals, is unlikely to be frequent

or in large numbers.


New Zealand Fur Seal

The New Zealand Fur Seal has established breeding colonies in South Australia

and Western Australia. This species is quite rare in Victorian waters, but a small

breeding colony has established at Kanowna Island near Wilsons Promontory.

This species mainly feeds on fish, squid and octopus and, occasionally, seabirds.

The New Zealand Fur Seal has not been sighted in the coastal waters

surrounding the Project area but it is likely to occasionally visit the area (Biosis


Australian Sea Lion

Australian Sea Lions historically bred in Bass Strait. Breeding colonies are now

restricted to South Australia and Western Australia. Individuals may reach

waters off Gippsland. Although this species may be an occasional, transient

visitor, it is generally unlikely to occur in the Project area (Biosis Research


5.5.3 Marine reptiles

The Leatherback Turtle is the only species of marine reptile that has been

recorded in the Project area. The Leatherback Turtle is protected under the

EPBC Act (listed as vulnerable) and it is also listed under the FFG Act.

Leatherback Turtles are the largest of the sea turtles reaching an average of

1.6 metres in length. The distribution of this species extends into tropical,

subtropical and temperate waters throughout the world. Leatherback Turtles

occur in the tropical and temperate waters of Australia, primarily off the coast of

Queensland, New South Wales and Western Australia.

There are no large Leatherback Turtle rookeries known from Australia, but

scattered nesting occurs along the south Queensland coast from Bundaberg to

Round Hill Head and along the coast of Arnhem Land from Coburg Peninsula to

Maningrida.


It is likely that a small and dispersed population of Leatherback Turtles visit

Victorian waters but they are rarely encountered. There has been only one

known citing of a Leatherback Turtle in 1989 in the Project area. This

observation was of a dead specimen that washed up on Williamsons Beach.

This species is unlikely to regularly use the Project area (Biosis Research 20082,


5.5.4 Seabirds

A total of 31 marine birds has been recorded from within five kilometres of the

Project area from field surveys conducted for the Project and database queries

(Atlas of Victorian Wildlife and Birds Australia New Atlas). Biosis Research

conducted field surveys of seabirds in the Project area during August to

November 2007 and March to May 2008 and observed 17 marine bird species.

Eleven species are listed in the EPBC Act or in the FFG Act. Table 5-7 lists these

species and their level of protection.

Table 5-7 Seabirds recorded in the Project area

Common name Scientific name EPBC FFG

Fairy Prion Pachyptila turtur Vulnerable -

White-bellied Sea Eagle Haliaeetus leucogaster Migratory Listed

Short-tailed Shearwater Puffinus tenuirostris Migratory -

Red-necked Stint Calidris ruficolis Migratory -

Sharp-tailed Sandpiper Calidrisacuminata Migratory -

Common Sandpiper Actitis hypoleucos Migratory -

Hooded Plover Thinornis rubricollis - Listed

Lesser Sand Plover Charadrius mongolus Migratory -

Double-banded Plover Charadrius bicinctus Migratory -

Sanderling Calidris alba Migratory -

Caspian Tern Sterna caspia Migratory -

Little Tern Sterna albifrons Migratory -

The Little Penguin Eudyptula minor - -


Common name Scientific name EPBC FFG

Australasian Gannet Morus serrator - -

Silver gulls Larus novaehollandiae - -

Pacific gulls Larus pacificus - -

Crested tern Sterna bergii - -

Black-faced Cormorant Phalacrocorax fuscescens - -

Great Cormorant Phalacrocorax carbo - -

Red-capped Plover Charadrius ruficapillus - -

Sooty Oystercatcher Haematopus fuliginosus - -

Southern Fulmar Fulmarus glacialoides - -

Common Diving-petrel Pelecaniodes urinatrix - -

Little Black Cormorant Phalacrocorax sulcirostris - -

Pied Cormorant Phalocrocorax varius - -

Little Pied Cormorant Phalocrocorax melanoleucos - -

Darter Anhinga melanogaster - -

Australian Pelican Pelecanus conspicillatus - -

Whiskered Tern Chlidonias hybridus - -

White-fronted Tern Sterna striata - -

Black-winged Stilt Himantopus himantopus - -

Musk Duck Biziura lobata - -

Fairy Prion

The Fairy Prion is listed as vulnerable in the EPBC Act. It is abundant in south-

east Australian waters. This species has known breeding areas on coastal

islands of Australia including those off Tasmania, Wilsons Promontory and

south-east Australia. It is commonly seen offshore in areas surrounding the

continental shelf and it is likely to occur in the Project area (Biosis Research



White-bellied Sea Eagle

The White-bellied Sea Eagle is a protected species that may occasionally utilise

both the estuary and open sea environments of the Project area. This species

has been recorded once during 2007 over the foreshore area of the Project area


Short-tailed Shearwater

The Short-tailed Shearwater, commonly called the Muttonbird, is a migratory

species and is protected under the EPBC Act. The breeding range of this species

extends along coastal southern Australia, and there are high concentrations

centred on Bass Strait and coastal Tasmania.

The entire population of this species migrates annually to high latitudes of the

north Pacific. Non-breeding birds may depart as early as February, whilst

breeding adults usually leave between late March and April. Chicks usually

depart during late April to very early May. Short-tailed Shearwaters then return

to Victoria during September.

This species forages widely at sea and has been known to travel as far as 150 to

200 kilometres away from a colony site. The offshore environment of the Project

area is a likely foraging area for this species, and they are also likely to pass

over this area during migrations. The closest breeding population to the Project

area is on the south coast of Phillip Island (Biosis Research 20082, Technical

Appendix 13).

Red-necked Stint

The Red-necked Stint inhabits the Williamsons Beach area and the marine

environment of the Project area (Biosis Research 20082, Technical Appendix 13).

Sharp-tailed Sandpiper

The Sharp-tailed Sandpiper is a migratory species. It occurs in the estuarine

environment of the Project area (Biosis Research 20082, Technical Appendix 13).


Common Sandpiper

The Common Sandpiper is a migratory species that migrates annually to south-

eastern Australia between August and May. The Common Sandpiper is likely to

occur in the area surrounding the lower Powlett River. It may also move into the

Project area’s offshore marine environment (Biosis Research 20082, Technical

Appendix 13).

Hooded Plover

Hooded Plovers inhabit the coasts of southern mainland Australia and Tasmania.

The Victorian population of this species is currently estimated to be between

334 to 538 individuals.

In Victoria, the main habitat of this species is wide, open, sandy beaches and

exposed areas of sand at the mouths of rivers and creeks. Hooded Plovers nest

in pairs above the high tide line or in the sand dunes of exposed ocean beaches.

Eggs have been recorded in Victoria between August and March.

Hooded Plovers breed in the Project area and inhabit the beach area between

the Powlett River mouth and Lower Powlett Road. Field surveys conclude that

there are likely to be three Hooded Plover breeding pairs currently resident in

the coastal area near the Plant site. Breeding pairs appear to be successful, as

chicks have been observed during these surveys (Biosis Research 20082,


Lesser Sand Plover

The Lesser Sand Plover is a migratory species that migrates annually between

August and May to areas along the Victorian coast. This species may occur

around the estuarine areas of the lower Powlett River and the Project area


Double-banded Plover

The Double-banded Plover occurs at Williamsons Beach. It is a migratory

species that is present in Australia annually between February and September.


Sanderling

The Sanderling is a migratory species that migrates annually between August

and April to areas of south-eastern Australia. The Sanderling occurs in the

Williamsons Beach area and also in the Project area and estuarine environments

of the Powlett River (Biosis Research 20082, Technical Appendix 13).

Caspian Tern

The Caspian Tern is a migratory species that inhabits the coastal zone and is

likely to occur in the Williamsons Beach area. It is likely to utilise the area

surrounding the lower Powlett River (Biosis Research 20082, Technical

Appendix 13).

Little Tern

Little Terns breed on beaches in Gippsland, from Lakes Entrance eastward.

They may occur in the Project area at any time, but are not known to breed in

this area (Biosis Research 20082, Technical Appendix 13).

The Little Penguin

Although not listed under the EPBC or FFG Acts, the Little Penguin is an

important species in the local area as there is a significant colony of Little

Penguins on the southern shores of Phillip Island. This population is located

approximately 25 kilometres from the Project area. This population of Little

Penguins is the largest breeding area in Victoria and has an estimated

population of 26 000 breeding birds.

Little Penguins are resident year-round in the Bass Coast marine environment.

Penguins feed at sea throughout the year. During the spring and summer

breeding season penguins spend more time ashore, typically at traditional

colony sites (Biosis Research 20082, Technical Appendix 13).

This species characteristically feeds on small schooling fish of open waters

rather than reef fish. Prior research undertaken on the foraging patterns of this

species found that anchovies and pilchards are the Little Penguin’s main prey

species.


Research undertaken on the Little Penguin’s swimming speed indicates that it

can reach sustainable underwater swimming speeds of 0.85 metres per second.

The maximum speed for short bursts is up to 1.7 metres per second.

Research on the movements of the Little Penguins from Phillip Island indicates

that the majority of movements by all age classes are westward from Phillip

Island. Less than 10 per cent of movements occur toward the Project area,

which is south-east of Phillip Island. Little Penguins are expected to utilise the

Project area. Several deceased Little Penguin specimens have been recorded in

the Project area (Biosis Research 20082, Technical Appendix 13).

5.6 Protected marine species

Database searches have identified 47 EPBC-listed species (threatened and/or

migratory) and FFG-listed species within five kilometres of the Project area, but

only 16 of these are considered likely to occur in the Project area. These species

are listed in Table 5-8. Species unlikely to occur in the Project area (e.g.

Australian Grayling, Southern Elephant Seal) are not included in this table, but

are discussed further in Volume 1, Chapter 6 Matters of National Environmental

Significance.

The following table also lists the migratory species likely to occur in the Project

area. This provision of the EPBC Act covers Australia’s obligations as a signatory

to various international conventions and treaties for the conservation of

international migratory species. Listed migratory species has not been deemed

to be a controlling provision under the EPBC Act for the Victorian Desalination

Project.

Some terrestrial birds (not listed in this table below) are also protected under

the EPBC Act. For example, the Orange-bellied Parrot has been previously

recorded at the Powlett River mouth and one kilometre upstream of the Powlett

River mouth. This and other protected terrestrial bird species that may occur at

the Plant site are discussed in Chapter 6, Volume 3 Desalination Plant.


Table 5-8 Protected marine biota listed under the EPBC Act and FFG Act likely to occur in the Project area

Common name Scientific name Likely occurrence in Project area EPBC FFG

Mammals

Killer Whale Orcinus orca Likely Migratory -

Humpback Whale Megaptera novaeangliae

Likely Vulnerable and

Migratory

Listed

Southern Right

Whale

Eubalaena australis Likely

Endangered

and Migratory

Listed

Fish

Great White Shark Carcharodon carcharias

Likely Migratory and

Vulnerable

Listed

Birds

Fairy Prion Pachyptila turtur Likely Vulnerable -

Short-tailed

Shearwater

Puffinus tenuirostris Recorded Migratory -

Red-necked Stint Calidris ruficolis Recorded Migratory -

Sharp-tailed

Sandpiper

Calidrisacuminata Recorded Migratory -

Common

Sandpiper

Actitis hypoleucos Likely Migratory -

Hooded Plover Thinornis rubricollis Recorded - Listed

Double-banded

Plover

Charadrius bicinctus Recorded Migratory -

Sanderling Calidris alba Recorded Migratory -

Caspian Tern Sterna caspia Likely Migratory Listed

Little Tern Sterna albifrons Likely Migratory Listed


Common name Scientific name Likely occurrence in Project area EPBC FFG

White-bellied Sea-

eagle

Haliaeetus leucogaster

Recorded Migratory Listed

Reptile

Leathery Turtle Dermochelys coriacea

Recorded Vulnerable and

Migratory

Listed

Of the listed mammal species, a few individuals of the Southern Right Whale

and the Humpback Whale are considered likely to pass through or near the

marine environment of the Project area during their annual migrations, between

May and December. The Project area does not provide important habitat for an

ecologically significant proportion of the populations of any of these species


One bird species, the Fairy Prion, has been recorded in the local area and is

considered likely to forage at the Desalination Plant site from time to time.

However, the Project area is not considered to provide important habitat for this

species (Biosis Research 20082, Technical Appendix 13).

Individuals of the EPBC-listed Leathery Turtle could occasionally pass through

the marine environment associated with the marine intake and outlet structures.

However, there are no important populations of this species in the Project area,

and the area does not provide important habitat for an ecologically significant

proportion of this species (Biosis Research 20082, Technical Appendix 13; CEE


Marine Invertebrates

There are thirteen marine invertebrate species that are protected under the FFG

Act. These species are presented in Table 5-9. There are three species of

crustacean, seven species of echinoderm and three species of mollusc. The

majority of marine invertebrates listed on the FFG Act are endemic to Victoria.

Little is known of the biology of these species.


Table 5-9 FFG Act protected marine invertebrate species

Taxa Common name Environment Habitat Location

Crustaceans

Athanopsis australis

Southern hooded

shrimp

Bay Sand, mud, reef (5-12 m) Port Phillip Bay and Bridgewater Bay

(Vic)

Eucalliax tooradin

Ghost shrimp Bay Fine sand (2-5 m) Swan Bay and Crib Point (Western

Port) (Vic)

Michelea microphylla

Ghost shrimp Bay Sandy gravel (19 m) Crib Point (Western Port) (Vic)

Echinoderms

Amphiura triscacantha

Brittle star

species

Bay and

Channel

Posidonia and Heterozostera

seagrass beds (subtidal)

Nooramunga and possibly Western

Port (Vic) and Spencer and St Vincent

Gulfs (SA)

Apsolidium densum

Sea-cucumber

species

Open Coast Rocky shallows (0-2 m) Apollo Bay and Flinders (Vic)

Apsolidium handrecki

Sea-cucumber

species

Bay Rocky shallows (on rock

platforms)

Merricks (Vic), Arno Bay (SA) and

Trigg Island (WA)

Ophiocomina australis

Brittle star

species

Channel Posidonia and Heterozostera

seagrass beds and on Pinna

bivalves (subtidal)

Nooramunga (Vic) and Spencer and

St Vincent Gulfs (SA)

Pentocnus bursatus

Sea-cucumber

species

Open Coast Found living on shallow water

macroalgae (subtidal)

Cape Paterson (Vic), Beachport (SA)

and Cockburn Sound (WA)

Thyone nigra Sea-cucumber

species

Bay Bay habitats (subtidal) Corio Bay (Vic), St Vincent Gulf (SA)

and Bramble Pt, Princess Royal

Harbour (WA)

Trochodota shepherdi

Sea-cucumber

species

Channel Posidonia seagrass beds

(subtidal)

Nooramunga (Vic) and Spencer and

St Vincent Gulfs (SA)

Molluscs

Bassethullia glypta

Chiton Bay and Open

Coast

Under rocks in sand (intertidal to

10 m)

Southern Port Phillip Bay, Bass Strait

(Port Phillip Heads), Flinders (Vic)

and Stanley (Tas)

Platydoris galbana

Opisthobranch Bay Reef flat San Remo (Vic)

Rhodope genus Opisthobranch Bay Reef flat San Remo (Vic)


As illustrated in Table 5-9, nine of these species are found only in bay

environments and three occur in channel environments. These species are

therefore highly unlikely to occur in the Project area. The three species that are

found in open coastal environments and may potentially occur in the Project

area are the sea cucumbers Apsolidium densum and Pentocnus bursatus, and

the chiton Bassethullia glypta.

The sea cucumber, Apsolidium densum, occurs in rocky shallows and has been

recorded on the open coast at Apollo Bay and Flinders in Victoria. This species

is known from only four specimens. This species is unlikely to occur in the

Project area.

Another sea cucumber, Pentocnus bursatus, has been observed inhabiting

macroalgae near the Cape Paterson boat ramp in Victoria. This species is known

from only four specimens at this one locality. This population of individuals is

considered to be genetically distinct given that it broods its young and,

therefore, lacks a larval dispersal stage. This species is also unlikely to occur

in the Project area.

The chiton, Bassethullia glypta, occurs under rocks in sand and has been

recorded in both bay and open coast environments. This species has been

recorded in two open coastal environments at the Port Phillip Heads in the

Bass Strait and Flinders in Victoria. Both of these records are based on a single

collected specimen. This species is considered a very rare chiton that is only

known to occur in a very restricted area of central Victoria, where it requires

clean sand and good water flow. This species is unlikely to occur in the

Project area.

Fisheries Act

The Great White Shark and Family Syngnathidae (all species including

seahorses, seadragons and pipefish), previously described in section 5.4.2, are

listed as protected aquatic biota under the Fisheries Act 1995 (Vic). A permit is

required to take individuals of these species.


5.7 Marine pests

Various definitions of marine pests exist; typically, a pest is a non-indigenous

species that threatens human health, economic or ecological values. An

introduced or cryptogenic species is a species not native to the area that does

not adversely affect the environment into which they have been introduced.

A literature review was undertaken of marine pests within the Project area

bioregion and adjacent bioregions. The Project area falls within the Central

Victoria Marine Bioregion within the Central Victoria zone as defined by the

Integrated Marine and Coastal Regionalisation of Australia (IMCRA).

Neighbouring bioregions were also included in the marine pest survey:

• Port Phillip Bay (VES bioregion)

• Offshore waters adjacent to the Project area (CBS bioregion)

• Wilsons Promontory (FLI bioregion).

The literature review considered these areas to inform consequent impact

assessments. In context of the impact assessment, it is important to review:

• Pests that could be introduced to the Project area (species present in

adjacent bioregions and beyond and not in the Project area)

• Pests that could be transported from the Project area to adjacent

bioregions (species present in the Project area and not adjacent

bioregions).

Based on the literature review, 183 species were described as either introduced

or cryptogenic in the four IMCRA bioregions. The vast majority of these were

recorded in Port Philip Bay, which is a heavily invaded, but relatively contained

area. A total of 92 species are present within Port Philip Bay with no known

presence in the other bioregions. Marine pests known to be present at the

Project area are shown in Table 5-10.


Table 5-10 Introduced and cryptogenic species at the Project area

Scientific name Common name or group Presumed origin Recorded in adjacent bioregions

Bugula neritina Bryzoan North eastern Atlantic VES, FLI

Watersipora arcuata Bryzoan North eastern Pacific VES

Carcinus maenas European Green Crab Europe/Baltic Sea VES, FLI

Megabalanus tintinnabulum Acorn Barnacle Unknown VES, FLI

Monocorophium insidiosum English Corophiid England VES

Asterias amurensis Northern Pacific Seastar North western Pacific VES

Cordylophora caspia Ponto-caspian Hydroid

Black Sea and Caspian

Sea

-

Crassostrea gigas Oyster North western Pacific VES

Maoricolpus roseus New Zealand Screw Shell New Zealand VES, CBS, FLI

Teredo navalis Shipworm Unknown VES

Boccardia proboscidea Californian Spinoid Polydiaete

North eastern and north

western Pacific

VES

Polysiphonia brodiei Macro-algae North Atlantic VES

Gymnodinium catenatum Toxic dinoflagellate Unknown VES, FLI

In general, the adjacent bioregions of Wilsons Promontory and the waters

offshore of the Project area show only a low level of introduced species invasion

compared to the Port Philip Bay bioregion (GHD 20084, Technical Appendix 27).

Only one introduced species, a hydroid Cordylophora caspia, is known to be

present in the Project area with no representation in the other bioregions.

The hyroid is assumed to be native to the Black and Caspian Seas.

6.0

Ma

rine

socio

-eco

no

mic

6.0 Marine socio-economic

Chapter 6 Marine socio-economic 6-1

6 Marine socio-economic

This chapter presents the socio-economic existing conditions of the marine

environment in the vicinity of the Project area. This chapter summarises the

findings of specialist investigations from the following reports:


• Biosis Research (20087) Cultural Heritage Existing Conditions and Impact Assessment Report – Plant site (Technical Appendix 45)


• Maunsell Australia (Maunsell) (20085) Victorian Desalination Project Environment Effects Statement-Social Impact Assessment Report (Technical

Appendix 56).

6.1 Commercial fishing

Commercial fishing occurs both in the Project area and the surrounding coastal

waters. The commercial fisheries in the Project area are discussed below.











Technical Appendix

Chapter 6 Marine socio-

economic

6-2 Chapter 6 Marine socio-economic

6.1.1 Abalone

Abalone are gastropod molluscs. Two species of wild abalone, Blacklip Abalone

Haliotis rubra and Greenlip Abalone Haliotis laevigata, are harvested in Victorian

waters. Abalone live hidden in rocky reefs and feed on drifting pieces of

seaweed and seagrasses. Blacklip Abalone prefers high wave energy coastal

waters like the Project area, and populations of this species are found

consistently along the Victorian coastline (CEE 2008, Technical Appendix 31).

The Greenlip Abalone has a more restricted range that generally excludes high

wave energy coastal waters.

The Victorian abalone fishery is the most valuable of Victoria’s State-managed

fisheries. Abalone resources were worth an export value of $48 million during

2005-2006. The commercial abalone fishery is divided into areas or reef codes.

The reef code in the Project area is designated as 15.02, and the northern area

is 15.01. Abalone catches in both these areas have declined in the past two

years. These declines are most likely a result of voluntary size restrictions

imposed by local operators in 2006.

6.1.2 Rock Lobster

The Southern Rock Lobster Jasus edwardsii is a marine crustacean that prefers

to live in sheltered caves, under rocks and in crevices. They occur close inshore

and to depths of greater than 200 metres. They feed mostly during the night on

bottom-dwelling invertebrates, including small crustaceans and molluscs. Sharks

and octopus prey on this rock lobster (CEE 2008, Technical Appendix 31).

The rock lobster fishery is the second most valuable commercial fishery in

Victoria. This fishery has the largest number of operators and vessels in Victoria

and is important to the economy of some coastal towns (CEE 2008, Technical

Appendix 31).

Licensed operators regularly fish the reefs offshore from Wonthaggi for the

Southern Rock Lobster. Fishing for rock lobster in the vicinity of the Project has

increased gradually since 2002 to present, following a brief decrease in 2005.

Rock lobster catches have generally declined over the last 30 to 50 years most

likely due to high fishing pressure.


Currently, there are less than five operators fishing for rock lobster in the

Project area. High relief reefs in the Project area are regularly fished, and pot

buoys have been observed in the Project area.

6.1.3 Finfish (including live wrasse)

There is an active live finfish fishery in the Project region. The main fishing

method is hook and line fishing and fish traps. San Remo operators catch Blue-

throated Wrasse, leatherjacket and various reef perch for this trade. Live fish

are provided to restaurants and for export. The Blue-throated Wrasse is the

most common reef fish in this area. Barracouta and snapper are also caught in

reasonable quantities. Finfish catching effort fluctuates from year to year with

typically between 40-60 days of fishing effort per year in the Project region.

6.1.4 Scallops

Southern Scallops inhabit the soft seabeds throughout the Bass Strait from

Victoria to Tasmania. Scallops are found on soft seabeds that range from fine

silts to coarse sands. The commercial fishery is managed under joint

agreements between the States and the Commonwealth. Scallop catch is highly

variable depending on season. Monthly quotas are in place during the scallop

fishing season. Scallop fishing is usually closed from June to November each

year. There is little scallop fishing in the Project area. Discussions with scallop

fishers in Victoria have indicated that scallop fishers rarely use the Project area.

6.1.5 Trawl fish species

Some approved trawling methods occur in the Project area. Over 30 scalefish

and shark species are trawled in Victorian waters over a range of water depths.

Trawling in the Project area targets school whiting (Silago spp.), with flathead

and a variety of other species also caught (at depths between 10 to 60 metres

over sandy seabed). Most school whiting in Victoria occur along the Ninety Mile

Beach. They are a relatively small whiting (generally smaller than 30

centimetres), which occur in large schools over sandy seabeds.


There are a range of other inshore trawl fish species which may occur in the

Project area including jackass morwong (Nemadactylus macropterus), yank-

and sand-flathead (Platycephalus speculator and P. bassensis), silver trevally

(Pseudocaranx dentex), various gurnard, red mullet (Upeneichthys sp.) and

some dories. These species are widely distributed and may be targeted from

time to time by Danish Seine vessels and inshore trawlers, though mostly in

waters east of Wilsons Promontory.

Only one Danish Seine vessel now appears to be based at San Remo. The San

Remo-based vessel fishes over a wide area of Bass Strait including the general

Project area. The seabed in the immediate Project area is unlikely to be suitable

for Danish seine fishing.

6.1.6 Southern Squid Jig Fishery

The Southern Squid Jig Fishery operates within the Project area. The most

common squid fished in this industry is the Arrow Squid Nototodarus gouldi. The distribution of the Arrow Squid is not well known, but it is likely to follow

food species over a wide area. The squid is commonly found at depths of 50 to

200 metres, where they aggregate near the seabed during the day and disperse

at night.

This species of squid is short-lived, with most individuals reaching a maximum

age of 12 to 18 months. They obtain rapid growth by feeding on small surface

fish (e.g. pilchards) and crustaceans (CEE 2008, Technical Appendix 31).

Sharks, seals and other fish eat squid.

Vessels from a range of ports from Victoria and Tasmania fish for squid in the

central region of the Bass Strait. The period from February to June is the main

squid fishing season, and there is usually a peak catch during May. The seasonal

variation in squid catch may largely be due to the commitment of operators to

other fisheries during spring and summer and not the abundance of squid.

Although some of the Southern Squid Jig Fishery operations occur within the

Project area, it is unlikely that these fishing operations are regular.


6.1.7 King George Whiting

Although King George Whiting occur along the southern coast of Australia, the

main commercial King George whiting fishing areas in Victoria are Port Phillip

and Westernport Bays and Corner Inlet. There is no commercial and little

recreational fishing for King George Whiting in the Project area.

6.2 Marine recreational use

The coast between Kilcunda in the north and Coal Point to the south of the

Project area is a continuous stretch of beach backed by high dunes with an

opening for the Powlett River. This region surrounding the Project is used for a

number of marine based recreational activities including swimming and surfing,

diving, recreational fishing, recreational boating and kayaking. Other

recreational activities and tourism relevant to the Plant area are discussed in

detail in Chapter 12, Volume 3 Desalination Plant.

6.2.1 Game fishing, ocean angling and shore-based fishing

San Remo provides access to ocean waters for game fishing in the Project area.

Mako Sharks, tunas, Blue Whalers and Bronze Whalers are game species that

are known to inhabit the San Remo area. Anglers also fish for other species of

marine fish including Snapper, Flathead, Snook, Australian Salmon, School

Shark, Gummy Shark, Barracouta, Pike, wrasses, sweep and squid. Local anglers

utilise commercial charter vessels based at San Remo and Newhaven or operate

from their own vessels.

A survey conducted by the Bass Coast Shire found that fishing from boats is the

fifth most popular recreation activity (based on participation numbers), with

approximately 11 per cent of the population involved in this activity. Participants

are primarily in the 55 to 64 age range (Maunsell 20085, Technical

Appendix 56).

Shore-based beach fishing occurs along this section of coastline and is primarily

conducted by local people. Fishermen use Williamsons Beach both on weekends

and during evenings throughout the year. The Wonthaggi Angling Club holds

competitions at the beach several times throughout the year (Maunsell 20085,



6.2.2 Swimming and Surfing

Swimming and surfing occur in the Project area. Williamsons Beach is used for

surfing throughout the year and for swimming primarily during the summer

months. Swimming on this beach is somewhat limited due to high-energy surf.

Users visit this area during weekends and week day evenings. In a study

conducted by the Bass Coast Shire of residents’ recreational activities, swimming

at beaches and rivers ranked third in order of participation numbers for the

area. Approximately 24 per cent of the local population is involved in this

recreational activity.

6.2.3 Recreational boating and kayaking

Recreational boating occurs along the coastline between Phillip Island and

Inverloch. The Newhaven and San Remo boat ramps are popular launch sites.

The Bass Coast Kayak Club uses the area off Williamsons Beach for sea

kayaking. Club members meet weekly from September through to May at the

mouth of the Powlett River (Maunsell 20085, Technical Appendix 56).

6.3 Cultural heritage

6.3.1 Aboriginal heritage

The Project area is located in the Bun wurrung territory, an area that stretched

loosely along physical features, such as rivers, from Werribee and Melbourne in

the north to Wilsons Promontory, including the Mornington Peninsula and west

Gippsland. Coastal areas supplied ample food for the Bun wurrung people.

Aboriginal archaeological artefacts are primarily found on land, so the discussion

of Aboriginal heritage for the beach and adjacent Plant site are discussed in

Volume 3, Chapter 8 Cultural heritage.

6.3.2 Maritime heritage

An interrogation of the Heritage Victoria Shipwreck Database for a 10-kilometre

radius of the Project area found three shipwrecks: the Artisan, Eli Lafond and

Maori (Table 6-1). Only one wreck, the Artisan, has a location recorded.


Table 6-1 Shipwrecks lost within 10 kilometres of the Project area

Vessel name

Heritage Victoria shipwreck number

Date of wreck Vessel type Location/probable site

Artisan 45 23 April 1901 1155 ton 3-masted

wooden barque

Wreck Beach, near Harmers Haven, Cape

Paterson (known site)

Eli Lafond 213 13 February

1858

Wooden barque Off Kilcunda coast (probable site)

Maori 440 10 September

1863

3-masted, 2-deck

wooden barque

In general area of the eastern entrance

to Western Port

The Artisan is historically significant to the community of Wonthaggi. The vessel

has limited archaeological significance because it was totally destroyed. The

French barque Eli Lafond was likely wrecked near Black Head, Western Port,

though the exact location of the wreck is currently unknown. Black Head is

located near the mouth of the Bourne River on the Kilcunda coastline, about

eight kilometres east of the eastern entrance into Western Port. The Maori wreck site has not been located and locations of remains are deduced from

details of the wrecking event. It is possible that remains of this vessel could be

found close to the area designated for the Marine Structure (but see the results

of the sonar scan discussed below).

An additional 43 shipwrecks have been lost between Victoria and Tasmania

within Bass Strait. In many cases, the only known information about the

wrecking event has been the fact that the vessel did not reach its destination

and is considered lost en route. It is possible that these shipwrecks could occur

within the Project area as waves and currents can transport wreckage during

the wrecking event, as well as over time. Sidescan and multibeam sonar data

was examined to determine whether shipwrecks or associated material is within

the Project area. The data were from the north-west corner of the Project area,

approximately two kilometres offshore and running parallel to shore for

approximately 2.5 kilometres. Based on the sonar data, no shipwreck or debris

fields associated with wrecks occur within the Project area (Biosis Research


7.0

Co

nstru

ction

imp

act a

ssessm

en

t

7.0 Construction impact assessment

Chapter 7 Construction impact assessment 7-1

7 Construction impact assessment

This chapter discusses the Project’s potential environmental effects on the

marine environment that may occur during construction. The environmental

impact assessment for construction is based on specialist findings from the

following reports:

• Bassett (2008) Underwater Noise (Technical Appendix 22)

• Biosis Research (20082) Assessment of Marine Mammals, Birds, and Reptiles for the Desalination Project, Bass Coast, Victoria (Technical

Appendix 13)

• Biosis Research (20087) Cultural Heritage Existing Conditions and Impact Assessment Report – Plant site (Technical Appendix 45)


• Essential Economics (20082) Victorian Desalination Project Impact Assessment (Technical Appendix 11)

• GHD (20084) Invasive Marine Species (Technical Appendix 27)

• Maunsell Australia (Maunsell) (20085) Victorian Desalination Project Environment Effects Statement-Social Impact Assessment Report (Technical

Appendix 56).











Technical Appendix

Chapter 7 Construction

impact assessment

7-2 Chapter 7 Construction impact assessment

Marine construction activities for the Reference Project, as detailed in Chapter 2

of this Volume, would build the Marine Structures by tunnelling under the

dunes, beach and seafloor and would install the intake and outlet structures.

Self-elevating platforms (SEPs) would conduct marine drilling. These temporary

structures may be serviced (with materials and people) from land by marine

vessels and helicopters.

7.1 Impact assessment

This section discusses the potential impacts of construction activities of the

Marine Structures on the marine environment. Both the risk assessment and the

impact assessment recognise that, like the Reference Project, the Project must

comply with the Performance Requirements set out in Chapter 11 of Volume 1.

7.1.1 Risks assessed medium or above

The risk assessment was conducted for the Variations as well as the Reference

Project and impacts on the marine environment are applicable to these

Variations. Construction risks and potential impacts for the Variations – multiple

smaller conduits, passive screens at the intake head, pipeline diffuser and

alternate locations for the Marine Structures (low profile reef or sand in deeper

water) – are considered to be similar to the Reference Project and are discussed

below where applicable.

Table 7-1 sets out the risks associated with construction of the Marine

Structures which were rated medium or above. The risks are discussed in order

of activity and likelihood with those most likely to occur discussed first.

Table 7-1 Construction risks assessed as medium or above


Con

sequ

ence

Like

lihoo

d

Ris

k

Removal or damage of reef habitat Moderate Certain High

Removal or damage of sandy habitat Minor Likely Medium

Seabed clearing

Destruction of or disturbance to significant reef species Moderate Likely Medium




Con

sequ

ence

Like

lihoo

d

Ris

k

Impact pile driving impacting on fish Moderate Likely Medium

Use of air guns impacting on fish Moderate Likely Medium

Use of air guns impacting on smaller toothed cetaceans,

mammals and sea birds

Minor Likely Medium

Generation of noise

and vibration

Geophysical surveys other than air guns impacting on fish Minor Likely Medium

Small chemical/hydrocarbon spill or incident impacting on


Minor Almost

certain

Medium

Medium or significant chemical/hydrocarbon spill or incident

impacting on water column, intertidal marine biota and marine

ecosystems



hydrocarbons

Medium or significant chemical / hydrocarbon spill or incident

impacting on the marine park

Major Rare Medium

Release of spoil at the drill site impacting on reef biota and

ecosystems

Minor Likely Medium Production of drilling

spoil

Disposal of spoil at a selected oceanic location impacting on


Minor Likely Medium

Increase in marine traffic impacting on fishing and recreational

activities

Minor Almost

Certain

Medium

Introduction of flora and fauna marine pests from marine

vessels impacting on marine species


Movement of marine

vessels

Increase in marine traffic impacting on public safety Major Rare Medium

Introduction of abalone disease impacting on commercial

viability of abalone diving industry in the Project area

Extreme Unlikely High Use of construction

divers

Introduction of abalone disease impacting on abalone

communities





Con

sequ

ence

Like

lihoo

d

Ris

k

Social impacts of construction of Marine Structures – impacts

on amenity

Minor Certain Medium All construction

activities

Potential for reduced visitation and loss of business revenue

due to perception that the Wonthaggi / Kilcunda coastline is

becoming ‘industrialised’

Moderate Almost

certain

High

Construction

exclusion zone

Impacts on commercial fishing Minor Likely Medium

Increased access to

Williamsons Beach

People accessing Williamsons Beach impacting on threatened

fauna


The above risk assessment is based on accepted construction practices but does not take into account the mitigation measures



7.2 Seabed clearing

Some clearing of the seabed would occur to create a level platform for

placement of equipment including SEP legs, anchors and cables that would be

used to position and anchor the SEPs. This would likely disturb some biological

habitats and affect the associated biological communities, although disturbance

would likely be localised to around the SEPs. Benthic communities are most

likely to be affected by seabed clearing. There may be localised damage to the

seabed and the plants and animals that inhabit the affected areas. Generally,

marine mammals are expected to avoid disturbed areas due to noise and

vibration from construction activities, so it is unlikely that clearing activities

would affect these species.

Seabed clearing for the multiple smaller conduits and the pipeline diffuser

Variations is expected to encompass a similar area as the clearing required for

the Reference Project. Clearing for alternate Marine Structure locations (also a

Variation in the Reference Project) would also be similar to the Reference

Project as these locations would not be within marine sensitivity areas.


The consequence of these activities are not considered to be significant as SEPs

and associated infrastructure would be removed from the marine environment

upon completion of construction of the Marine Structures and it is expected that

these communities would recover to their original state after construction

activities are complete. Secondary effects due to clearing (such as dispersal of

sand from the seabed) would also only occur for a short period of time.

Disturbed areas in the marine environment tend to be rapidly colonised by a

succession of marine biota, usually resulting in a marine biological assemblage

similar to the community that existed prior to disturbance (CEE 2008, Technical

Appendix 31).

7.3 Generation of noise and vibration

Many marine mammals rely on sound as their primary method of

communication. Some species may even use echolocation to determine the

physical features of their surroundings. These animals communicate underwater

at varying frequencies. Therefore, artificial sources of underwater noise may

impact marine mammals by masking biologically important sounds. This could

induce a behavioural response causing a temporary threshold shift (TTS) or

permanent threshold shift (PTS) in hearing.

Pile driving may be required during construction (based on geological

conditions), depending on final siting of the Marine Structures. Pile driving, if

required, would emit noise and vibration. The noise from pile driving is generally

high level, low frequency and impulsive. The noise level from pile driving would

depend on the pile diameter, local geology and bathymetry. Intense, impulsive

signals such as those produced from pile drivers can affect fish, and noise levels

of a smaller magnitude can cause behavioural changes. Damage to hearing by

intense sound depends on the auditory threshold of the receiving species and

would therefore vary from species to species (Bassett 2008, Technical Appendix

22). Noise from pile driving is expected to affect individual fish but not

significantly affect species at the population level.

Geophysical surveys (including the use of air guns) used to characterise the

marine geology prior to construction have the potential to generate periodic

underwater noise and vibration.


Noise modelling was undertaken by Bassett (2008, Technical Appendix 22) using

a software implementation of the Range-dependent Acoustic Model (RAM) to

estimate geophysical survey construction noise and evaluate the consequence to

marine biota. Modelling was undertaken for boomers and sparkers (used in

geophysical surveys), which are mid-frequency sources used in seismic and

hydrographic survey. These devices would likely be used for geophysical surveys

for the Marine Structure tunnels.

Figure 7-1 presents the noise modelling results for geophysical surveys. Results

are presented between 16 hertz and 1 kilohertz. In order to provide a three-

dimensional picture of the noise, each individual figure shows the modelled

noise propagation along a transect radiating from the noise source. The noise

source can be seen at the left of each of the bathymetric tracks with red

indicating high noise levels. The variable line indicates the seabed. The colour

gradient shows the sound pressure level (SPL) expressed in decibels. The

modelling estimates the potential for some species of fish to be impacted within

two kilometres of geophysical surveys operating at a typical source level of 230

decibels (Bassett 2008, Technical Appendix 22).

The impact on cetaceans, sea birds, mammals and reptiles is considered lower

than the potential impact on fish. The soft start management procedure in the

EPBC Act Policy Statement 2.1, which regulates seismic testing activities as they

affect cetaceans, recommends a gradual increase of the geophysical source over

a 30-minute period. This is expected to alert animals and enable them to move

away from the disturbed area. Since this method would be required by the

Performance Requirements, cetaceans, fish, sea birds, mammals and reptiles

are not expected to be significantly affected by geophysical surveys including

the use of air guns (Bassett 2008, Technical Appendix 22).


Figure 7-1 Noise modelling results for geophysical survey at the intake location

Bassett 2008

7.4 Use of chemicals and hydrocarbons

Chemicals and hydrocarbons would be used for marine construction, largely for

vessel and equipment fuelling. These chemicals would not be placed in the

marine environment, but accidental spills could occur. Accidental spills of

hydrocarbons may affect:

• marine biota and ecosystems

• water column


• the intertidal community

• the marine parks in the region.

The level of impact is dependent on the types of chemical used and their

toxicity. The risk process identified that accidental small chemical or

hydrocarbon spills would be almost certain to occur during the construction

phase, but are likely to have only minor effects on any communities or

ecosystems because quantities of chemicals stored and used would generally be

small. Medium or significant spills are considered unlikely to occur. The PRs

require development and implementation of methods and management systems

to limit on-vessel storage and/or use of hazardous substances and dangerous

goods, which would reduce the risk of spills.

If a spill were to occur, it is expected to only affect individual marine biota,

rather than entire populations and any effects, though moderate, are likely to be

temporary and localised.

The risk of an accidental spill affecting the neighbouring marine park was rated

as low because the quantity of any spill is likely to be small and the marine

parks are located at a sufficient distance from the Project area to minimise the

impact. Accidental spills are not likely to have any significant or long-term

effects on any population of marine mammal, sea birds or reptiles (Biosis


7.5 Production of drilling spoil

Spoil will be generated from tunnelling and drilling for the Marine Structures.

Based on the Reference Project, if a suitable marine spoil disposal site can not

be identified, most of the drilling spoil will be collected on the jack-up barge and

later taken to land for disposal. Any impact on the marine environment is

expected to be minimal as the Performance Requirements specify disposal of

any spoil from marine construction in accordance with EPA Best Practice

Guidelines for Dredging and the National Ocean Disposal Guidelines.


7.6 Movement of marine vessels

Marine traffic would be largely from the movement of vessels to the SEPs from

the shore.

7.6.1 Increase in marine traffic

It is possible that the movement of marine vessels could disturb recreational

users in the Project area, especially fishing activities and affect public safety.

Any disruption is expected to have a minor effect on recreational and fishing

activities because the duration of the impact would be limited to the

construction period. The construction exclusion zone would limit interactions

between construction vessels and the public such that any impact would be

from the exclusion zone rather than marine traffic. The exclusion zone is

designed to protect public safety and would ensure that no public safety impacts

arise from increases in marine traffic.

7.6.2 Introduction of pests and disease

Movement of construction and support vessels and discharge of ballast waters

by vessels arriving from international and domestic locations have potential to

spread marine pests if not properly managed. Marine pests and disease could

also be transported via attachments to the hulls of ships (biofouling).

The spatial and time scale over which the transplant of an introduced species

may affect the marine environment is difficult to predict; however, the

movement of introduced species into areas where there are no natural controls

may have widespread ecological effects. The translocation of some pests can

cause changes to biodiversity in the immediate affected area. Compliance with

Commonwealth and State legislation requirements for ballast water would likely

reduce the probability of pest species translocations and standard operating

procedures have been developed in recognition of the risk that marine industries

pose in translocating marine pests. The movement of vessels to and from the

Project area poses no greater risk than any other marine industry in introducing

marine pests. However, the Performance Requirements require development

and implementation of a marine pest risk management process (including

monitoring) to further reduce the risk of the introduction, spread and

establishment of marine pests (GHD 20084, Technical Appendix 27).


7.7 Use of construction divers

The disease of greatest concern is the ganglioneuritis virus that affects abalone.

This disease appears to be spread by several vectors, including through the

action of ocean currents, the use of abalone as fishing bait and by attaching to

diving equipment and boats. Divers may be used to assist with sub-surface

construction. This disease was detected in the wild in western Victoria in May

2006 and has now currently spread approximately five kilometres from the

Twelve Apostils Marine National Park eastern boundary (CEE 2008, Technical

Appendix 31).

Although it is considered unlikely that this disease would be introduced to the

Project area, the consequence of this introduction would be serious as it may

have significant implications for abalone commercial fishing and the area’s

abalone population. Additionally, experience from the infection site in western

Victoria indicates that the disease can infect large areas after introduction (CEE

2008, Technical Appendix 31). The PRs require specific risk management

processes to limit the risk of introduction of this abalone disease in the Project

area (see section 7.11).

7.8 Construction affecting social Amenity

Collectively, construction activities are expected to affect the visual amenity of

the local area, as the Project may interrupt the quality of coastal views in some

areas. The coastal area is valued for its significant scenic landscape created by

the intersection between the coast and the Strzelecki foothills. The community

also values the views across to Phillip Island and east to Gippsland and the

scenic quality of the undeveloped tourist route near Phillip Island. Any effect

on amenity from construction is expected to be minor as construction activities

would be restricted to a small section of the coast and would only extend for the

temporary construction period (Maunsell 20085, Technical Appendix 56).


The community consultation for the Project identified a concern that the Project

would contribute to a general ‘industrialisation’ of the Wonthaggi coastline,

which could generally change the perception of the area and lower tourist visits.

Most tourism in the area occurs in and around Philip Island and well away from

the Project area. While a moderate impact on visitation and eco-tourism is

expected in the immediate area of Wonthaggi during construction, the

construction activities, as such, are of limited duration and are not expected to

appear to industrialise the area.

7.9 Exclusion zone

A construction exclusion zone would be required to ensure health and safety of

the general public. The temporary exclusion zone would preclude all marine

activities including commercial fisheries and recreational uses within this zone in

order to prevent the interaction between construction activities and other public

and commercial activities.

The construction area is frequently fished for rock lobster and abalone near-

shore and less frequently for shark and squid offshore (CEE 2008, Technical

Appendix 31). According to ABS census data (Essential Economics 20082,

Technical Appendix 11), there are 30 to 40 jobs out of a population of around

10 000 that are associated with the commercial fishing industry. The

aquaculture and fishing industries are very small with respect to total business

and employment (less than one per cent) in the area. Since the exclusion zone

would only preclude commercial fishing from a small area (approximately two

kilometres by two kilometres) and any reduction of commercial fishing would

affect only a small percentage of the population for only the short construction

period, the exclusion zone would only have a minor effect on commercial fishing

and it is not expected to have any long-term effects on commercial fishing in the

local area.


7.10 Increased access to Williamsons Beach

Construction activities would increase the number of people working in the

Project area and this could result in more people wanting to access the adjacent

beach area. People can disturb nesting Hooded Plovers nesting in the beach

area by flushing adults from active nests, which can increase the predation risk

to eggs. In general, Williamsons Beach, which currently only has a car park and

no associated amenities, has lower patronage than other beaches in the area

(Maunsell 20085, Technical Appendix 56). Since the Victorian Hooded Plover

population has been estimated to be between 334-538 birds, disruptions to the

breeding success of this species would have a moderate effect on Hooded

Plovers as any loss of individuals may lead to reductions in the viability of the

population in the local area or region (Biosis Research 20082, Technical

Appendix 13). Field surveys conclude that there are likely to be three Hooded

Plover breeding pairs resident in the coastal area near the Plant site. It is for

this reason that the PRs require the implementation of methods and

management systems to ensure no adverse effects on the dune system, beach

and intertidal zone from Project activities to minimise the loss of individuals

of significant species. In particular, the PRs require collaboration with Parks

Victoria and DSE to achieve additional protective measures such as fencing

off portions of the beach used by nesting Hooded Plovers to exclude people,

uncontrolled dogs and increased fox and cat control.

7.10.1 Risks assessed as low

The risk assessment for the Reference Project explored a comprehensive list

of potential environmental effects in order to identify the priority areas for

management and mitigation. The following risks have been assessed as and are

expected to have a minor or negligible effect on the environment with generally

a rare or unlikely probability of occurrence.

Release of grout to marine environment

The grout used to facilitate sub-surface construction rapidly solidifies and the

tunnels would largely be drilled deep below the seabed, so it is highly unlikely

that grout would be released to the marine environment.


Tunnel collapse

It is highly unlikely that any tunnel collapse would affect the marine

environment, as tunnelling would occur 15 metres below the seabed.

However, if this did occur, only a small area of the seabed would likely be

affected resulting in some disturbance or destruction to seabed habitat.

Any disturbance would only be temporary and the seabed would likely fully

recover (CEE 2008, Technical Appendix 31).

Release of bentonite

The tunnel-boring machine (TBM) that would create the tunnels for the Marine

Structures could use bentonite as a drilling fluid to lubricate and cool the drill-

cutting head. A malfunction of this machine may result in bentonite being

released into the marine environment. However, only in rare circumstances

would accidental release occur and any release of bentonite is expected to only

have a moderate effect on marine biota. These water-based drilling fluids

have low toxicity and any localised impact could be due to temporary

seabed blanketing.

Drilling noise affecting fish and marine mammals

Underwater noise that would be generated from drilling for the intake and outlet

risers has been assessed through noise modelling and this is considered to be a

low risk to marine biota (Bassett, 2008 Technical Appendix 22). The rate of

diminishing noise for drilling at the intake and outlet would be slightly less than

for seismic activities (discussed above) and drilling noise is generally low level,

low frequency and continuous with most energy concentrated below 1 kHz.

Since this is a level in which most whales have reduced hearing sensitivity,

only in rare circumstances would drilling affect cetaceans, and it is considered

unlikely that drilling would affect and fish and other vertebrate species

(Bassett 2008, Technical Appendix 22).


Helicopter noise

Helicopters may be used for transportation between the shore and the SEPs

during the construction period. Noise impacts from helicopters may be a source

of disturbance to birds, especially the beach-nesting species, the Hooded Plover.

Helicopters could also affect other marine biota. It is likely that there would be

some noise disturbance from this activity, but since helicopter movements are

not likely to be frequent and would only occur during the construction period,

the effect on Hooded Plovers and other biota is expected to be negligible


Lighting

Artificial lights may also have deleterious effects on birds, especially on seabirds.

Many seabirds fly or migrate at night. Artificial lighting can be disorienting and

may ‘trap’ large numbers of birds within a pool of light. Lighting impacts

associated with construction activities are expected to only affect individual birds

rather than an entire population. This impact would be contained in the local

area, and would only occur during the period of construction (Biosis Research


Underwater noise affecting recreational activities

Although it is possible that underwater noise generated by construction activities

could affect recreational activities, any impact would be temporary with no

lasting effect on recreational use of the area. Marine activities that generate

noise and vibration that may affect recreational users (e.g. helicopters) would

only occur during the construction phase during a short time period

(approximately 24 months) and then would cease. Therefore, it is considered

unlikely that noise and vibration from construction would affect the overall

recreational use of this area (Maunsell 20085, Technical Appendix 56).

Additionally, the PRs require minimising exposure of marine recreational users

to underwater (continuous) noise levels greater than 145 dB re 1 µPA.


Exclusion zone affecting recreational activities

It is also possible that the exclusion zone would preclude some recreational

activities (such as diving). However, any impact on recreation would likely be

minor because construction would only limit recreational activities in a small

area for a short period of time.

Tourism and visitation

Penguin and seals are the main wildlife visitor attractions in Bass Coast Shire,

although there is also some bird watching and occasional whale spotting.

Although it is possible that adverse effects on the penguin population and other

marine life from Project construction activities could affect long-term visitation

and eco-tourism activities in the region, with adoption of the PRs, the Project is

unlikely to have an impact on penguins, seals and other wildlife attractions

(Biosis Research 20082, Technical Appendix 13). Therefore, it is unlikely that the

eco-tourism industry would be adversely affected by the construction activities

and eco-tourism operators are not likely to experience a downturn in business

due to the Project. Any effects of the Project on eco-tourism would most likely

be restricted to the Project area with no effect on operators on Philip Island who

are responsible for the larger amount of employment and economic activity

(Essential Economics 20082, Technical Appendix 11).

Maritime heritage

Construction activities are not expected to affect maritime heritage in the

Project area. A systematic search of the Project area using the sidescan sonar

and multibeam data did not detect any areas of heritage interest within the

areas proposed for the Marine Structures. Therefore, any disturbance to the

seabed in this area is unlikely to affect any maritime heritage assets (Biosis


Marine vessel emissions

Emissions generated from the movement of marine vessels during construction

are unlikely to be sufficient to affect human health and interactions between the

public and construction vessels would be restricted by the exclusion zone

(Maunsell 20085, Technical Appendix 56).


7.11 Performance Requirements during construction

Performance Requirements (PRs) have been developed to provide an

environmental framework for management of potential impacts during

construction of Marine Structures. The PRs are focussed on the environmental

‘outcomes’ that the State wishes to achieve through Project delivery. The PRs

relevant to the management of construction impacts of the Marine Structures

are set out below. The full suite of PRs for the Project is provided in Volume 1

Chapter 11 as part of the overall Environmental Management Framework.

As part of the environmental impact and risk assessment process relating to

construction of Marine Structures, CEE (2008, Technical Appendix 31), Biosis

Research (20082, Technical Appendix 13; 20087, Technical Appendix 45), GHD

(20084, Technical Appendix 27) and Bassett (2008, Technical Appendix 22) have

identified a range of suggested management measures that could be

implemented to manage potential impacts. These suggested management

measures have been formulated in response to the Reference Project and

relevant Variations for the Marine Structures. In effect, the suggested

management measures demonstrate how the Reference Project and relevant

Variations can achieve the PRs. These detailed management measures have

formed an important input to the PRs for the Project.

The management measures suggested by CEE (2008), Biosis Research (20082,

20087), GHD (20084) and Bassett (2008) for the mitigation of impacts associated

with the construction of the Marine Structures address the following matters:

• managing the introduction of aquatic pests and diseases potentially

introduced by the transfer of equipment and construction vessels to the

construction site by ensuring:

- all international vessels comply with Australian Quarantine and

Inspection Service (AQIS) requirements

- all interstate vessels comply with State requirements

- a pre-entry risk assessment procedure is considered, determining the

likelihood of any vessel associated with construction of the

Desalination Plant introducing marine biofouling pests of concern to

the Project bioregion


• minimising the effects of the self elevating platform (SEP) and associated

equipment on the marine environment by:

- positioning the SEP, jack-up legs, anchors and cables to avoid areas

of high relief reef

• minimising or avoiding the interaction between fishing operators, fishing

gear and the marine construction site by:

- consulting with the fishing operators and advising them of the nature

of construction activities and timing, possible exclusion zones and the

risks to their fishing gear and catches

- taking particular care when construction vessels are moving through

fishing grounds between the construction site and home ports

- limiting vessel movements to daylight hours to and from the

construction sites

• managing potential impacts of seismic survey on cetaceans by:

- ensuring compliance with the measures prescribed in the EPBC Act

Policy Statement 2.1 – Interaction between offshore seismic

exploration and whales

- minimising the generation and propagation of impulsive and/or

repetitive noise, such as from offshore impact pile driving underwater

- ceasing drilling activities, where practicable, if a baleen whale, larger

toothed whales such as the killer whale or false killer whale, or

leatherback turtle is spotted within 50 m of activities

• managing the physical and ecological integrity of the Williamsons Beach,

the dune systems and the intertidal zone by:

- minimising project personnel’s access to these areas during Project

activities

- banning dogs from the construction site and consult with Parks

Victoria to determine further measures in the protection of

Williamsons Beach and Kilcunda-Harmer’s Haven Coastal Reserve

- educating project personnel about conservation and exclusion zones

- monitoring the locations and breeding success of resident Hooded

Plovers along Williamsons Beach at least monthly until the plant is in

routine operation

- developing measures that manage injured sea birds if impacted by

construction activities.


The PRs proposed for the marine environment are outlined in Table 7-2.

Table 7-2 Performance Requirements

Timing Subject

D&C O&M Objective Performance Criteria Performance Requirements

Coastal

processes

Protect coastal

processes. Minimise impacts on sand

movements, wave patterns

and currents.

Comply with the Performance Criteria.

Demonstrate through modelling of hydrodynamic

processes such as tides, currents, winds and sand

movements, that the Project will have no adverse

effect on coastal processes.

Monitor and report the effect of Project Activities

on coastal processes.

Detail the measures proposed to address the

results of the monitoring undertaken to achieve

compliance with the Performance Criteria.

Coastal

integrity

Protect the

physical

integrity of the

dune system,

beach and

intertidal zone.

No surface disturbance of

the dune system, beach and

intertidal zone.

No measurable loss to the

integrity of the coastal

assets including the dune

system, beach and intertidal

zone.


Develop and implement methods and

management systems designed to ensure no

adverse effect on the dune system, beach and

intertidal zone from Project Activities including:

Induction programs for Project personnel

Minimise access outside public access pathways


on the dune system, beach and intertidal zone.

Coastal flora

and fauna

Protect the

ecological

values of coastal

habitat.

No reduction in habitat

values for significant

species.

Minimise loss of significant

species’ individuals.

No removal of coastal

vegetation.







Implement management measures to minimise

access of construction personnel to Williamsons

Beach and foreshore reserve, particularly during

Hooded Plover breeding season (August to

February)

Collaborate with Parks Victoria and DSE to

achieve additional protective measures such as

fencing off portions of the beach used by

nesting Hooded Plovers to exclude people,

uncontrolled dogs and increased fox and cat

control

Ensure that external lights are kept to a


Timing Subject


minimum, that they are positioned as low to the

ground as is practicable and that they are

shielded to avoid light spill upward and toward

the foreshore, beach and sea

Implement a program of monitoring the

locations and breeding success of resident

Hooded Plovers along Williamsons Beach to

measure the impact of Project Activities and

inform opportunities for mitigation. This should

continue at least monthly from prior to

construction until the plant is in routine

operation.

Implement a program of monitoring for the

Orange-bellied Parrot from March to September

prior to and during construction activities and

inform opportunities for mitigation.

Marine flora

and fauna –

general

Protect marine

flora and fauna.

No significant

impact on

Bunurong

Marine National

Park and on the

protected values

of marine parks.

Minimise to the extent

practicable the impacts on

marine flora and fauna from

Project Activities.

Limit impacts on ecology of

continuous high relief reef.

Develop, implement and maintain methods and

management systems to protect marine flora and

fauna.

No construction in the designated areas, which

creates a long-term impact, presented in Figure

PR Sensitivity Area – Marine Area, in Technical

Appendix 5.

Trenching is not permitted in the designated areas

presented in Figure PR Sensitivity Area – Marine

Area, in Technical Appendix 5.

Manage any geotechnical investigation program to

avoid significant impacts on the high relief reef in

the designated area and marine fauna in general.

Any spoil from marine construction to be disposed

of in accordance with EPA Best Practice Guidelines

for Dredging and the National Ocean Disposal

Guidelines for Dredged Material.

Marine

amenity –

recreational

Minimise

disruption to

marine

recreational

activities.

Outside any marine

exclusion zone (for diving

safety) no significant impact

on diving, surfing,

recreational fishing or

marine boating activities.

Limit disruption to divers

outside construction

exclusion zones.



management and systems to minimise disruption

to recreational activities.

Turbidity or colouration impacts from the outlet

should not be visible from the shoreline.


Timing Subject


Commercial

fishing and

marine

tourism

Minimise

disruption to the

commercial

fishing industry

and marine

tourism.

Minimise restrictions on

commercial fishing and

marine tourism activities.

Comply with the Performance Criterion.


management systems that seek to achieve

effective consultation and communication with the

commercial fishing and marine tourism industry in

relation to potential restrictions and disruptions

during construction.

Marine pests

Avoid the

introduction,

spread and

establishment of

marine pests.

Compliance with the

Commonwealth and State

legislative requirements for

Ballast Water.


Develop and implement a marine pest risk

management and monitoring process (including a

process directed to addressing the risks of

introducing pests by vessels and equipment).

Develop and implement a risk management

process specifically for limiting risk of abalone

disease.

Underwater

noise and

vibration –

ecological

Protect

cetaceans.

Compliance with EPBC Act

Policy Statement 2.1 –

Interaction between

offshore seismic exploration

and whales.


Conduct geophysical survey of Project Activities in

accordance with the procedures outlined under

the EPBC Act Policy Statement 2.1 - Interaction

between offshore seismic exploration and whales.

Underwater

noise and

vibration –

marine diving

activities

Protect marine

diving activities

from

underwater

noise and

vibration.

No significant impact

outside any marine

exclusion zone on marine

diving activities.


Outside any exclusion zone, minimise exposure of

marine recreational users to underwater

(continuous) noise levels greater than 145 dB re

1µPA.


management systems that ensure effective

consultation and communication with marine

divers in relation to marine noise and vibration.

Marine –

navigation

Protect coastal

access on

marine waters

for vessels.

Minimise impact on safe

passage of non-Project

vessels along the coast.


Identify and implement any requirements for

notifications for vessel movements by Marine

Safety Victoria.

8.0

Op

era

tion

s imp

act a

ssessm

en

t

8.0 Operationsimpact assessment

Chapter 8 Operations impact assessment 8-1

8 Operations impact assessment

This chapter details the Project’s environmental effects on the marine

environment that may be generated during operations. The impact assessment

is based on a comprehensive risk assessment and specialist findings from the

following reports:

• ASR (20088) Near-Field Diffusion Numerical Modelling of the Proposed Desalination Plant Outlet (Technical Appendix 30)

• ASR (20087) Mid-Field Numerical Modelling of the Desalination Plant Outlet Plume (Technical Appendix 29)

• ASR (200810) Preliminary Particle Dispersal Modelling Seasonal and Spatial Variations (Technical Appendix 33)

• Bassett (2008) Underwater noise (Technical Appendix 22)


• Consulting Environmental Engineers (CEE) (2008) Marine Biology


• GHD (20083) Water and Sediment Quality Assessment (Technical Appendix 23)

• GHD (20084) Invasive Marine Species Specialist Report (Technical Appendix 27)

• Hydrobiology and CSIRO (2008) Toxicity Assessment for Victorian Desalination Project (Technical Appendix 24)

• Maunsell Australia (Maunsell) (20085) Social Impact Assessment report (Technical Appendix 56).











Technical Appendix

Chapter 8 Operations impact

assessment

8-2 Chapter 8 Operations impact assessment

The key operational features of the Marine Structures requiring impact

assessment are:

• the effect of the intake on marine biota

• the effect of the discharge stream on marine biota and water quality.

The impact assessment looks at each of these separately and is based on a

combination of ecotoxicity testing, water quality sampling and analysis,

modelling and ecological assessment.

The risk assessment was conducted for the Variations as well as the Reference

Project and impacts on the marine environment are applicable to these

Variations. Operation risks and potential impacts for the Variations – multiple

smaller conduits, passive screens at the intake head, pipeline diffuser and

alternate locations for the Marine Structures (low profile reef or sand) – are

considered to be similar to the Reference Project and are discussed below

where applicable.

8.1 Intake of seawater

The intake would draw seawater from the ocean waters at the Project area,

which would then be transferred to the Desalination Plant via a tunnel. In the

Reference Project, the intake would be located offshore in water over 15 metres

deep. The intake mushroom head structure would have coarse grills sufficient to

reduce entrainment of large marine biota at the opening. A Variation of this

aspect in the Reference Project is finer screens at the intake that would require

air backwashing.

The intake may affect individual organisms through the following three major

physical mechanisms:

Entrainment – Entrainment is the process of biota being drawn into

the intake because they are unable to leave the ingoing stream of water.

Large and small biota may be initially entrained in the intake stream.

Entrapment – is the process of biota being drawn into the intake tunnel

after entering the offshore intake structures and not being able to escape.

This process generally applies to larger organisms (including large fish,

seabirds, mammals and reptiles).


Impingement – the removal of biota from the marine environment by

being drawn into the intake and caught on screens at the onshore screens.

The size of the organism impinged is related to the offshore screen opening

size because although biota that swim into the intake could swim out again,

it is likely they would be drawn down into the intake conduit. Generally,

impingement relates to fish and larger mobile invertebrates.

Each of these mechanisms may result in removal of some individuals. Processes

of entrainment, impingement and entrapment would depend on characteristics

of the intake structure (including the positioning of the intake structure, the size

and positioning of the screens, the speed and direction of the intake stream and

the effects of chlorine dosing) as well as characteristics of the affected organism

(including size and mobility). In the Reference Project, a number of design

features have been included to minimise entrainment, entrapment and

impingement including raising the intake above the seabed and placing grills on

the intake.

8.1.1 Impact assessment – Intake

This section discusses the potential impacts of the operation of the intake

structure on the marine environment. Both the risk assessment and the impact

assessment recognise that, like the Reference Project, the Project must comply

with the Performance Requirements set out in Chapter 11 of Volume 1.

Approach to intake impact assessment

In order to assess the impact associated with the intake of seawater the

following studies were undertaken:

Assessment of the species of marine life in the region (fish, birds, mammals

etc) most likely to be affected by the intake as well as sampling of fish egg

and larvae offshore from the Project area (CEE 2008, Technical Appendix

31 and Biosis Research 20082, Technical Appendix 13).


Particle modelling, comprising hydrodynamic modelling and particle

dispersal modelling (ASR 200810, Technical Appendix 33). This was

undertaken to assess percentage reductions due to the intake of particles,

representing plankton such as eggs and larvae zooplankton and

phytoplankton. Model results were then used for an ecological assessment

of the consequence of plankton removal at a population scale.

Assessment of commercial fish species that may be impacted by the intake

and the economics of this impact (Essential Economics 20082, Technical

Appendix 11).

Models were used to simulate larval transport and the impact of the intake

based on the Reference Project. The modelling simulated the transport of

particles and these particles are relevant to dispersal of eggs, zooplankton,

phytoplankton and fish larvae. Modelling was conducted with advice from

marine biologists and the choice of model was based on the duration of the

larval period. One model was used to simulate larval period of one, two, seven

and 14 days. The model included data for wind driven currents, tidal currents

and coastal-trapped waves. A second model was used to simulate larval periods

of 30, 60 and 120 days. The model included data for wind driven currents and

coastal-trapped waves. Tidal currents were not included due to their limited

effect on overall larval transport at this scale as wind and other forces provide

the net transport over time. Sophistication and biological reality were included in

the models by considering larvae with uniform distribution, buoyant larvae

concentrated in the top of the water column, larval production concentrated in

Port Phillip Bay and Western Port and a concentration of larval production along

the coast. Particles were released at intervals during the model run to simulate

ongoing biological production and survival in the model for the period

corresponding to the larval duration being studied.

Modelling was undertaken over approximately one year (using meteorological

and oceanographic data recorded over 2004) with longer runs used to

incorporate longer larval periods. Subsequent modelling has compared the

model outputs from 2005 to modelling from 2004 and has considered seasonal

variation in hydrodynamic conditions.


Modelling simulated the marine environment with and without the seawater

intake. When the seawater intake was modelled, particles reaching the intake

region were removed from the modelling environment to simulate larval

entrainment. The intake was modelled with a seawater uptake of 18.5 cubic

metres per second, which is slightly larger (and hence conservative) than the

maximum intake of a 200 gigalitre per year plant, thus providing a conservative

result. Model results were presented as a percentage change in particles,

indicating the per cent larvae removed by the intake in a given area. The

models provide an indication of the extent of effect of entrainment on larval

densities but do not consider natural biological and ecological factors beyond

the source area that also affect larval densities as these are assumed to be the

same for the modelled scenarios with and without the intake (CEE 2008,

Technical Appendix 31). (The modelling methodology is discussed further in ASR

200810, Technical Appendix 33.)

Risks assessed medium and higher

Table 8-1 sets out the risks associated with the intake structure which were

rated medium and higher. The risks are discussed in order of activity and

likelihood with those most likely to occur discussed first.

Table 8-1 Risks from operation of the intake assessed as medium and higher


Con

sequ

ence

Like

lihoo

d

Ris

k

Entrainment of eggs / larvae with localised release, short life history and

becoming adults nearby (if intake located over a reef environment)

Moderate

Certain

High

Entrainment of eggs / larvae with localised release, short life history and

becoming adults nearby (if intake located over a sandy environment)

Minor Likely Medium


duration, settle in particular places (if intake located over a reef

environment)


Intake of

seawater


duration, settle in particular places (if intake located over a sandy

environment)

Negligible Certain Medium



Con

sequ

ence

Like

lihoo

d

Ris

k

Entrainment of eggs / larvae that are released over wide areas, have long

duration and do not settle in particular places


Entrainment of eggs / larvae that have widespread distribution, short life

cycle and rapid turnover (includes holoplankton)


Flow on effects from seawater intake – impacts on ecosystem interactions Moderate Likely Medium

Impingement, entrainment and entrapment of fish and mobile

macroinvertebrates

Minor Likely Medium




In the risk assessment, the risk of the intake on reef species with short

planktonic and larval phases was assessed as high while the risk is expected to

be a medium risk to sandy benthic species with short larval phases. The impact

of entrainment to reef species is due to the likelihood that reef species larvae

would remain relatively close to the seabed and in the area most likely to be

affected by the force of the intake. The risk for sandy benthic species is

considered less because if the intake were to be located above sandy areas,

it would be located higher above the seabed to minimise the potential for

entrainment of sand and this may decrease entrainment of benthic species

larvae. The Reference Project locates the intake head within the sandy

seabed and at a height which minimises sand intake and entrainment of

benthic species.

The following assessment applies to the Reference Project intake. Passive intake

screens, a Variation to the Reference Project, would further reduce the intake of

planktonic larvae, zooplankton and small fish species.


Eggs and larvae

The loss of eggs and larvae may translate into reductions in adult populations

with subsequent impacts on ecosystems and ecosystem interactions. However,

reductions in larvae do not necessarily translate into an equivalent reduction in

adult population abundance due to the large size of larvae populations relative

to adult populations, the high spatial and temporal variability and the episodic

nature of successful replenishment events (CEE 2008, Technical Appendix 31).

These secondary and long-term effects of the intake on adult populations and

ecosystem interactions are considered collectively for larvae of all species in the

section below.

Eggs and larvae have been categorised based on life history and the marine

community affected by the loss of the eggs and larvae. For modelling purposes

and the following discussion, larvae have been broadly categorised based on

larval duration:

• very short larval duration

• short larval duration

• longer larval durations.

Very short larval durations

Populations of organisms with a localised release of eggs and larvae in close

proximity to the intake are expected to be at highest potential risk from

entrainment of planktonic eggs and larvae. This risk, however, would occur only

in close proximity to the intake. Species that fall into this category have a very

short planktonic existence ranging from minutes to days. Species are typically

reef invertebrates and algae. For example, Ecklonia radiata, a large brown kelp

that forms subtidal habitat, has a larval period of less than a couple of days.

Species with a short planktonic phase generally settle in the local vicinity with

dispersal distance of metres to hundreds of metres.


Hydrodynamic modelling of particles shows that larvae with very short larval

durations would be diminished slightly within a small area near the intake

(Figure 8-1). The zone of effect diminishes with increasing distance from the

intake structure. The figures below show a computer-generated map of the

Project area, and shaded areas indicate the percentage change in numbers of

larvae due to modelled entrainment into the intake structure. Blue areas show

zones with the predicted greatest reduction in planktonic numbers for species

with very short larval durations. Model output for entrainment of one day larval

durations predict a small reduction of 0.5-1.0 per cent in the number of larvae

that visits an area extending approximately 1.8 kilometres parallel to the shore

and one kilometre wide. The model predicts no entrainment outside of these

areas. This is a small reduction in numbers of larvae even within the zone of

influence and is very small considering the overall population of these larvae

present in Bass Strait and surrounding waters.

Entrainment is likely to affect two-day larval periods over a larger area than

species with larval periods of less than two days. Modelling shows the zone of

effect stretching further along the coast. Modelling shows similar larvae

reductions for two day duration larvae in a larger area extending approximately

seven kilometres parallel to the coast and 1.5 kilometre wide. Although this is a

larger area of influence than one-day larvae, the predicted maximum larval

reductions in this larval category from entrainment would be minor in the short-

term and would not be detected more than one kilometre from the intake (CEE

2008, Technical Appendix 31). Again, the model predicts no entrainment outside

of these areas. This is a small reduction in numbers of larvae even within the

zone of influence and is very small considering the overall population of these

larvae present in Bass Strait and surrounding waters.


Figure 8-1 Change in particle visits due to the intake for larval periods of 1 day (upper) and 2 days (lower)

Source: ASR 200810


Short larval durations

Other species may have a longer planktonic phase ranging from days to weeks

and disperse more widely during the planktonic phase. Most remain within

hundreds of metres to a few kilometres from the point of release. Reef fish

species that fall into this category include wrasse, which may exist in a

planktonic phase for approximately one week. Abalone, another reef species,

also has a relatively short larval period of only approximately five to 14 days.

Modelling results for planktonic phases of seven to 14 days (presented in Figure

8-2) show the increased spatial influence of the intake on longer larvae

durations. As these larvae are in the water longer they have more opportunity to

disperse, which is evident as a band stretching along the coast with reductions

of up to 1.5 per cent at locations closest the intake. This reduction, which occurs

to larvae only in this area, is small. Modelling for larvae with a seven day larval

period shows a predicted reduction of 0.15 per cent of the larvae that visit an

area extending approximately 16 kilometre parallel to the shore and two

kilometres wide. The modelling shows that longer larval periods (i.e. 14 days)

are likely to experience a reduction of 1-1.5 per cent of the larvae that visit an

area extending two kilometres parallel to the shore up to approximately one

kilometre offshore. Modelling results show particles entrained by the intake

originate from an area between Cape Paterson and the Western entrance of

Western Port, but during summer and spring, modelling shows particles only

coming from within the Project area.

Overall, modelling predicts small reductions in larval abundance in a minimal

area near the intake. It is likely that the predicted maximum larval reductions

from entrainment would be minor and would not be detected more than one

kilometre from the intake. These reductions are tolerable additions to natural

mortality of planktonic populations (CEE 2008, Technical Appendix 31).


Figure 8-2 Change in particle visits due to the intake for larval periods of 7 days (upper) and 14 days (lower)

Source: ASR 200810


Longer larval durations

Species with longer larval durations may remain as larvae for months and may

be distributed over large areas by ocean currents. Species in this category are

predominantly invertebrates and pelagic and demersal fish species (CEE 2008,

Technical Appendix 31). Modelling for longer larval durations was conducted for

30, 60 and 120 day larval periods (shown in Figure 8-3 and Figure 8-4).

Modelling shows that species with a 30 day larval duration could experience

reductions of a very low proportion of larvae from as far as Cape Schanck and

east of Wilsons Promontory. The reduction in larvae in the majority of this

region would be from 0.1-0.5 per cent. Outside this area there is expected to

be no reductions in larvae.

Species with larval durations of 60 days are expected to have a similar reduction

over the same area as the 30 day larval duration modelling. The area

experiencing 0.5-1.0 per cent reduction in the number of larvae that visit an

area that extends west to Kilcunda and east as far as Inverloch and Venus Bay.

In a small band stretching one kilometre along the coast adjacent to the Project

area, reductions of 1-1.5 per cent may occur.

The modelling indicates a larger area of effect of the intake on longer larvae

durations with reductions in larvae predicted at increasingly greater distances

along the coast because particles spend more time in the model and have a

greater chance of drifting past the intake. Larval durations of 120 days have a

predicted reduction of 0.5-1.0 per cent in an area that extends from Kilcunda

past Inverloch to the west of Cape Liptrap.

Even for this longer larval period, the predicted loss of larvae is expected to be

small. In the short-term it is likely that the predicted maximum larval reductions

from entrainment would be minor and would not be detected more than one

kilometre from the intake.


Figure 8-3 Change in particle visits due to the intake for larval periods of 30 days

Black area indicates Phillip Island. Source: ASR 200810


Figure 8-4 Change in particle visits due to the presence of the intake for larval periods of 60 and 120 days

Black area indicates Phillip Island. Source: ASR 200810


A number of long larvae duration species are found in the Project area,

which may be affected by entrainment. Benthic reef species that are remotely

spawned and have long duration are expected to be at medium risk from

impacts of entrainment. Species that utilise the sandy seabed as habitat, that

spawn remotely, have long larval durations, and settle in particular places

(e.g. the demersal fish King George Whiting) are also expected to be at medium

risk from entrainment. For species that have a widespread distribution, short life

cycle and rapid turnover (such as species of phytoplankton and zooplankton),

the effects of entrainment are likely to be minor and undetectable.

Ecosystem interactions

For all three larval durations, modelling shows that the intake could remove

up to 1.5 per cent of the individuals from an area near the intake parallel to

the coast. These larval reductions do not necessarily translate into reductions

in adult populations. In general, the effect of larval mortality on population

replenishment is subject to a number of factors and is uncertain (CEE 2008,


The effect of occasional high natural mortality events for larvae may not be

detectable in adult populations that are either highly variable themselves,

long-lived or highly mobile. However, over the duration of the project

(30 years), progressive reduction in population replenishment may result in

decreased numbers of some species. This may result in community composition

changes as demonstrated in interactions between community components.

Indicators of change within the marine system may include:

• changes in the proportion of settling larvae due to higher mortality as a

result of entrainment

• the appearance of biological spatial gradients in benthic species close

to the intake

• changes in the ecological community composition.


Many species have a strategy of abundant production of larvae to protect the

population from high mortality rates. Most species that produce an abundance

of larvae can have high natural mortality (from 99 per cent and up to 99.9999

per cent) and still sustainably replenish adult populations. Since larvae are

generally produced in large numbers to tolerate natural mortality, these

populations may tolerate additional small loss of larvae via artificial uptake, such

as by the intake structure, and adult populations may not be affected by this

reduction in larvae. Comparison of annual larval entrainment estimates for

periods 20 years apart from the South Bay power plant in California showed

that the numbers of larvae entrained annually was similar, indicating that the

populations supplying these larvae also were not changing dramatically over

time. There is some evidence that small levels of proportional mortality due to

entrainment for wide ranging pelagic species (such as northern anchovy studied

in California) has little effect on adult populations. Additionally, long term

monitoring of larvae at many Californian intakes has consistently found that

the same larval species assemblages occur over time (CEE 2008, Technical

Appendix 31).

Based on field studies of entrainment, particle models and oceanographic

modelling, there may be some short-term lowering of plankton numbers for

certain species and there may be moderate effects on community characteristics

due to intake of larvae. Populations further from the entrainment of larvae

would be less affected than those close to the intake, since the removal of

larvae would be diffuse, low-level and generally within natural variability.

However, there may still be medium to long-term effects on certain species and

community characteristics. From two kilometres to 10 kilometres from the intake

it is unlikely that there would be an ecological transition related to operation

of the Marine Structures. Marine ecosystems located further from the intake

(i.e. two to 14 kilometres), including Bunurong Marine National Park, the effect

on particles would likely be diffuse, low-level and within natural population

variations, so that these areas, including the marine parks, are unlikely to be

affected by the intake and it is highly unlikely that a biological effect would be

found in community structure.

Indirect food chain impacts, including those on iconic species such as Little

Penguins and whales, are not expected. This is because effects on holoplankton

from the intake have been assessed as diffuse, low-level and within natural

population variations. As a result entrainment of this group is not likely to have

any flow-on effects through the food chain.


Effects on fish and mobile macro-invertebrates

Intake design features have been included to minimise the potential for intake

of biota. For example, ‘velocity caps’ have been used in the Reference Project,

which could result in water being drawn into the intake in a horizontal plane at

lower speeds. Using velocity caps has been shown to reduce fish entrainment

and impingement by 97 per cent compared to open ended pipes with no velocity

controls (CEE 2008, Technical Appendix 31). Additionally, grills on the intake

head would preclude any large marine organisms.

The effect of the intake on populations of fish is difficult to gauge, as there is

little species-specific information. Major seawater intakes off the Victorian

coastline and at the Torrens Island Power Station in South Australia are situated

in embayments rather than on the open coast and do not record entrapment.

In southern California, the Huntington Beach power station draws approximately

1 900 megalitres per day, which is generally analogous to intake estimates for

the Desalination Plant. From 2003 to 2004, the Huntington Power plant

impinged 12 694 individual fish from the ocean from approximately 36 species,

corresponding to approximately 290 kilograms of fish while 150 kilograms of

invertebrates were impinged including jellyfish, octopus shrimp and spiny

lobster. However, it is considered that these findings are not necessarily

indicative of impingement for the Desalination Plant. It is likely that the

Huntington Power plant would impinge more biota than the Desalination Project

due to the larger volume of intake water and the higher productivity of

Californian waters. The effect of impingement of fish is expected to be minor

on the fish populations in the Project area. Although some individual fish and

macro-invertebrates may be entrained, entrapped or impinged in the intake, this

is considered unlikely to occur in such numbers as to constitute more than a

minor effect (CEE 2008, Technical Appendix 31).

Risks assessed as low

The risk assessment for the Reference Project explored a comprehensive

list of potential environmental effects in order to identify the priority areas for

management and mitigation. The following risks have been assessed as low

and are expected to have a minor or negligible effect on the environment with

generally a rare or unlikely probability of occurrence.


Additional impacts of entrainment, entrapment and impingement

Marine mammals

The grills on the intake head (required by the PRs) would preclude any large

marine organisms including penguins and seals. Therefore, it is expected that

there would be a negligible impact on these biota due to operation of the intake.

Pipefish

Many pipefish (e.g. Weedy and Leafy Sea Dragons) do not have planktonic

larvae as they brood their young and produce live, free swimming juveniles.

These young are likely to disperse only tens of metres, depending on their

mobility. These juveniles are unlikely to be affected by the intake and any effect

on pipefish species is expected to be minor.

Larvae from the Powlett River estuary

Modelling shows that only a low proportion of entrainment of larvae at the

mouth of the Powlett River or offshore from the River. Additionally, since little of

the Powlett River intake travels towards the proposed intake position, few larvae

are likely to be entrained by the intake.

Commercially significant species

The key commercial fisheries in the region are abalone, rock lobster and reef

fish. Rock lobsters have very long larval periods of up to two years. Larval

density in the Project region is very low. Consequently, the importance of larval

settlement to recruitment of rock lobsters in the area is uncertain. At worst, they

would be susceptible to entrainment similar to long-lived larvae.


There may be concern that Marine Structures are in the pathway of King George

Whiting larval dispersion between western Victoria and Corner Inlet. These

larvae require periods of moderate to strong east going current during spring to

transport them, typically over a one month period, from approximately the

region of the entrances to Port Philip and Western Port to the entrance to

Corner Inlet. The contribution of the King George Whiting stock in Corner Inlet

to the breeding population in South Australia and western Victoria is uncertain,

but is likely to be relatively small considering the relatively large adult stocks in

South Australia and large recruitment in South Australia, Port Phillip and

Western Port. Overall, it is possible that the stocks of juvenile and adult King

George Whiting in Corner Inlet could be reduced by up to 0.5 per cent over a

period of three to four years (the period of maturation of juvenile to adult fish)

due to the Project, although the proportion is likely to be far less. In any case,

the effect on the total Victorian and South Australian population is likely

to be minor.

Abalone and wrasse (reef fish) have relatively short larval periods of five to

fourteen days depending on environmental conditions. Abalone larvae appear to

maintain their position close to the seabed and possibly within the kelp canopy

to optimise the chances of returning to coralline algal encrusted rock in reef

habitat when they become competent to settle. This general pattern may be the

same for wrasse and a variety of other reef fish and invertebrate species with

short larval periods. As for the general reef community, some impacts are likely

to influence the population of species. In general, the effect of the Project on

most pelagic and demersal commercial species is likely to be very small and

limited to a low proportion of larval reduction (less than 0.25 percent) over a

small proportion of their range. Therefore, the risk of the Project to these

species is likely to be negligible and commercial fisheries are unlikely to be

impacted by the intake of seawater.

Chlorine dosing

In the Reference Project, chlorine dosing would be applied to the intake stream

at the intake head in order to prevent biofouling of the intake tunnel. This

chlorination would affect biota entrained in the intake but it is expected to have

a negligible effect on the marine environment, as chlorination would take place

within the head, and chlorine is unlikely to be released into the marine

environment with the steady operation of the intake pumps.


Underwater noise during operation

Underwater acoustic noise modelling was conducted to investigate the

noise likely to be produced during operation of the Marine Structures and

the propagation of the noise through the marine environment (based on

bathymetric and seawater characteristics of the ambient environment).

Only noise from the intake pumps was modelled using measurements made at

the AGL Torrens Island power station. Vessel noise was not modelled as toothed

whales generally have low hearing sensitivity at the noise frequencies typically

produced by support vessels, while other more sensitive species would be likely

to move away from vessel noise. The diffuser outlet would operate under

gravity with very little noise and vibration and therefore was not

numerically modelled.

Underwater noise modelling predicted that the intake pumps would generate a

sound source level of 145 decibels at a distance of one metre from the source.

Noise generated by the seawater intake structure could cause a temporary

threshold shift to some mammals, cetaceans and marine reptiles within five

metres of the intake. However, these species are expected to have a

behavioural response to the noise within at least 50 metres of the intake (within

25 metres for Leatherback Turtles). Therefore, the consequence of underwater

noise and vibration on marine biota would be temporary and localised, with

behavioural responses only evident at maximum distances of 50 metres from

the intake heads. The consequence of behavioural response from operational

noise was assessed as negligible. Noise resulting from the operation of the

intake heads would likely be masked by ambient noise within a few hundred

metres of the intake heads (Bassett 2008, Technical Appendix 22).

Although there is a possibility that underwater noise would affect recreational

activities, operational noise from the intake is likely to be indistinguishable from

the ambient noise environment. Modelling shows that operational noise would

likely be masked by the existing noise in the environment within a few hundred

metres of the intake head (Bassett 2008, Technical Appendix 22). Therefore, the

effect on people in the marine environment is likely to be negligible.


Summary of intake impacts

The intake design in the Reference Project (as required by the Performance

Requirements) uses best practice design criteria to minimise the entrainment,

entrapment and impingement of marine life. Furthermore, the particle modelling

and literature review show that entrainment would only remove a small portion

of biota in the marine waters. Overall, the specialist investigations and impact

assessment show that:

Particle modelling predicts entrainment of a small proportion of larval

entrainment (up to 1.5 per cent) in an area of influence and no entrainment

outside of these areas. This is a small reduction in numbers of larvae even

within the zone of influence and is very small considering the overall

population of these larvae present in Bass Strait and surrounding waters.

The intake is likely to result in the entrapment of smaller marine biota such

as juvenile fish. The amount of adult fish drawn into the intake is likely to

be minor.

Appropriate external grill spacings to prevent the entrapment of medium

sized biota such as Little Penguins has been included in the Reference

Project and is required by the Performance Requirements.

Within a close proximity of the intake (approximately within 500 metres)

there is a likelihood of a change in the community structure of smaller

biota. It is likely that a gradient structure would establish in this area over

the duration of Project operation.

It is highly unlikely that a biological effect would be detectable on

marine community structure in the adjacent marine park over the

duration of the project.

Other impacts from operation of the intake are considered to have

a minor or negligible impact.


8.2 Discharge

In the Reference Project, concentrate from the Desalination Plant would be

discharged into the marine environment through a diffuser arrangement

located offshore. The saline concentrate would be approximately double the

salinity of seawater. The concentrate released to the ocean would contain

two main components:

• concentrated seawater

• trace chemical residuals from the desalination processes

Discharge of the concentrate from the Desalination Plant during operation must

be in accordance with the State Environmental Planning Policy Waters of Victoria

(SEPP (WoV)). The aims of SEPP (WoV) for the marine environment are to

protect beneficial uses from the effects of the discharged concentrate. The

investigation of existing conditions at the Project area has determined that, for

the purposes of SEPP (WoV), the Project area is in the segment: Marine and

Estuarine environments – Open Coasts. The following beneficial uses require

protection for this segment:

• aquatic ecosystems that are largely unmodified

• water suitable for

- primary contact recreation

- secondary contact recreation

- aesthetic enjoyment

- indigenous cultural and spiritual values

- non-indigenous cultural and spiritual values

- aquaculture

- industrial and commercial use

- fish, crustaceans and molluscs for human consumption.


Clause 11 of the SEPP (WoV) indicates that in order to protect beneficial uses,

a level of water ‘health’ needs to be maintained for the marine environment,

which means that the water needs to be free of pollutants (e.g. nutrients,

sediment, salt and toxicants) at levels that may render the water suitable

for beneficial uses. SEPP (WoV) affords 99 per cent ecosystem protection for

largely unmodified open coasts of Victoria.

Determining what will constitute 99 per cent ecosystem protection requires:

• analysis of concentrate characteristics by ecotoxicity testing to determine

the effects of the discharge on marine organisms and water quality analysis

based on meeting the trigger values in SEPP (WoV) to determine a “safe

dilution factor” which is the dilution at which beneficial uses are protected

as required by SEPP (WoV)

• hydrodynamic modelling of the dispersion and dilution of the concentrate

which would occur in the marine environment to determine the area where

the safe dilution factor may not be reached.

In combination, these enable an assessment of the ecosystem effects.

Further, the area where beneficial uses may not be protected because the

safe dilution factor is not reached is the area for which declaration of a mixing

zone may be required.

A ‘mixing zone’ may be declared by the EPA and form part of the Project’s

discharge licence. According to SEPP (WoV), a mixing zone is:

An area contiguous to a licensed waste discharge point and specified in that licence, where the receiving environmental quality objectives otherwise applicable under the Policy do not apply to certain indicators as specified in the licence. This means that some or all beneficial uses may not be protected in the mixing zone.

This process is shown in Figure 8-5.


Figure 8-5 Specialist investigations for discharge impact assessment


8.2.1 Ecotoxicity testing

SEPP (WoV) requires consideration of the acute and chronic toxicity through

the process of ecotoxicity testing. Standard ecotoxicity tests involve placing

samples of test biota in solutions for set time periods (generally 48 to 96 hours).

Test biota are also placed in solutions with no effluent to provide a baseline

against which to test any toxicological effects from exposure. After a period of

exposure to the effluent, in a series of dilutions, the lethal and impaired effects

on the test organism are assessed and the relationship of toxicity to dilution can

be determined.

It is well established in ecotoxicology that the magnitude of any adverse effect

on organisms, be they osmoregulatory or toxic, is a function of both the length

of exposure and concentration of the waste stream or toxicant. The nature of

this relationship is that the shorter the duration of the exposure the higher the

concentration needs to be to cause adverse effects and conversely the longer

the duration the lower the concentration needs to be to cause the same

adverse effect.

The exposure times of biota to the high concentrations associated with the

discharge are very short, in the order of seconds (ASR 20088, Technical

Appendix 30). Toxicity testing over periods of days is considered to provide a

very conservative estimate of toxicity related to the discharge (Hydrobiology

and CSIRO 2008, Technical Appendix 24).

Toxicity testing (conducted by Hydrobiology and CSIRO 2008, Technical

Appendix 24) tested the sensitivity of a suite of marine organisms (including a

microalgae, sea urchin, scallop, macroalgae, amphipod and fish species) to

serial samples of the desalination plant discharge from the Perth Seawater

Desalination Plant. All of the selected species, with the exception of the sea

urchin and fish are found in the coastal waters of Southern Victoria. These two

species are substitutes for similar sea urchin and fish species found in Southern

Victoria coastal waters (see further discussion in Hydrobiology and CSIRO 2008,

Technical Appendix 24). (It should be noted that different species are used in

different locations for ecotoxicity testing. As such, the results reported here may

not be representative of the toxicity effects of the concentrate from the Perth

Seawater Desalination Plant on marine organisms in Cockburn Sound,

Western Australia.)


The Perth Seawater Desalination Plant intake and discharge were compared

with the characteristics of the Reference Project and ambient water quality at

the Project area. Differences in seawater composition between Perth and

Victorian sampling were few and thought to be insignificant in the context of

this assessment. Differences in process design between the Perth plant and

Reference Design have been assessed together with their impact on the waste

stream composition for the Victorian Plant. It was concluded that a meaningful

comparison can be made between the samples and predicted waste stream.

This validates the use of ecotoxicity testing using Perth’s discharge on Victorian

receiving water and Victorian marine life and also use of results generated from

this analysis to guide decision-making for the Project (i.e. identification of

acceptable ocean waste discharge composition). It is concluded that ecotoxicity

testing on the Reference Project discharge would have similar results to those

generated by the current ecotoxicity testing using Perth’s waste discharge on

Victorian marine biota.

The toxicity testing was undertaken in accordance with the Australian and New

Zealand Guidelines for Fresh and Marine Water Quality. The tests provided a

range of acute and sub-chronic endpoint measurements of toxicity. Since the

sub-chronic tests exposed a sensitive life stage of the organisms it can, for the

purposes of this testing, be treated as chronic testing data as it is reflective of

whole life-cycle toxicity. The testing calculated the concentration of the

discharge required for 99 per cent ecosystem protection as defined by

SEPP (WoV).

The testing considered three discharge scenarios. The Reference Project RO

concentrate was tested as well as the pre-treatment discharge to ocean (an

Option in the Reference Project). Testing was also conducted on the infrequent

discharge (during commissioning or a rare event such as upset conditions) of

the RO concentrate and pre-treatment supernatant. The tests used discharges

from the Perth Seawater Desalination Plant. A salinity adjusted test was also

conducted to determine the effect of salinity on marine biota using salinity-

adjusted seawater from the Perth Seawater Desalination Plant intake.

Only the Reference Project test is discussed in this Chapter. Discussion of

potential toxicity of the pre-treatment waste disposal in the marine environment,

an Option in the Reference Project, is discussed in Technical Appendix 24

(Hydrobiology and CSIRO 2008).


8.2.2 Water Quality

The water quality trigger values for 99 per cent ecosystem protection for the

marine waters in the Project area were compiled from environmental water

quality objectives for the Open Coast segment in SEPP (WoV). Water Quality

trigger values are levels below which there exist a low risk that adverse

biological effects would occur. The water quality trigger values for protection for

the marine waters in the Project area were compiled from environmental water

quality objectives for the Open Coast segment in SEPP (WoV). Where no SEPP

(WoV) environmental quality objectives were available, the default trigger

values for marine ecosystems and toxicants in marine waters provided by the

Australian and New Zealand Guidelines for Fresh and Marine Water Quality were

considered. Adopted default trigger values are listed in Table 8-2. Only high

reliability trigger values were considered for toxicants; the monitoring data were

used to provide locally derived trigger values for other parameters monitored for

the Project that do not have associated high reliability trigger values.

Trigger values determined for the Reference Project have been compared to the

likely discharge constituents to inform the level of safe dilution required to

provide protection of the marine environment.

Table 8-2 Adopted default trigger values for marine waters in the Project area

Parameter Units Project area ambient water quality Trigger value

Physiochemical parameters

TSS mg/L 1.3 2.0

TDS (by analysis) g/L 38.6 41.6

TDS (by calculation from ions) g/L 36.9 40.6

Total alkalinity as CaCO3 mg CaCO3/L 121 132

Major ions

Chloride mg/L 20 200 20 940

Sulfate mg/L 2 910 3 130

Bromide mg/L 62 83

Fluoride mg/L 0.9 1.1

Calcium mg/L 420 460




Magnesium mg/L 1 400 1 550

Sodium mg/L 11 430 12 030

Potassium mg/L 490 540

Total barium mg/L 5.9 7.3

Total boron mg/L 4.3 5.4

Total strontium mg/L 7.6 11

Total metals

Aluminium µg/L 13.8 57.7

Iron µg/L 16.9 71.8

Arsenic total µg/L 1.6 2.1

Cadmium µg/L 0.1 0.7

Chromium total µg/L 0.23 0.47

Copper µg/L 0.25 0.3

Lead µg/L 0.1 2.2

Manganese µg/L 0.58 80

Mercury µg/L 0.05 0.1

Molybdenum µg/L 11.9 16.4

Nickel µg/L 0.18 7

Tin µg/L 1.75 10

Zinc µg/L 1.75 7

Nutrients

Ammonia mgN/L 0.01 0.02

Nitrite + Nitrate mgN/L 0.00 0.01

Total nitrogen mgN/L 0.18 0.20

Soluble reactive phosphorus mgP/L 0.00 0.01

Total phosphorus mgP/L 0.01 0.03




Organic compounds

Total organic carbon mg/L 1.3 3.8

Source: GHD, 20083

8.2.3 Hydrodynamic Modelling

Hydrodynamic modelling was conducted to estimate the potential dynamics of

concentrate dispersal and dilution based on local oceanographic processes and

oceanic characteristics. Modelling of the dispersal of the seawater concentrate

was carried out on two scales:

Near-field modelling was undertaken to determine the characteristics

and dilution of the plume within a scale of up to 50 metres of the outlet

(i.e. while the plume is still under the influence of the discharge jets).

Mid-field modelling was used to estimate the behaviour of the seawater

concentrate plume at the Project area scale. Mid-field modelling assessed

the behaviour of the plume over a broader area than near-field modelling

and considered the influence of factors such as local hydrodynamics,

bathymetry, wind and wave action on dilution and dispersion.

This modelling is described in ASR (20087 ,Technical Appendix 29 and 20088,



Near field modelling of the discharge in the immediate vicinity of the outlet and

the performance of various diffuser configurations was undertaken using the

computer software VisJet 2.0 (VisJet). The model incorporated information on

physical and chemical characteristics of the Project area marine waters, physical

and chemical characteristics of the concentrate and engineering design of the

outlet (i.e. diffuser configuration) based on the Reference Project. An ambient

salinity of 35 parts per thousand was selected for the near-field modelling (and

an ambient salinity of 35.5 parts per thousand for the mid-field modelling).

Following a series of sensitivity runs involving currents from 0.02 to 0.04 metres

per second, the Reference Project was modelled with an ambient current of 0.04

metres per second. The salinity of the discharge was assumed to be 65 parts

per thousand. The total discharge rate from the diffuser was modelled as 11.5

cubic metres per second, which is a slightly higher discharge rate than the

Reference Project.

Mid-field modelling simulates the behaviour of the concentrate at greater

distances from the diffuser where it would be less influenced by the diffuser

configuration of the Reference Project and more influenced by hydrodynamics of

the receiving waters and plume characteristics. The midfield modelling used the

near field modelling results from VisJet as an input. The Powlett River was

included in the modelling with freshwater input to the ocean of approximately

1.4 cubic metres per second, and the model incorporated the influence of the

intake. The intake location was modelled approximately 500 metres in a

north-north-westerly direction from the outlet.

Several scenarios were modelled, which primarily differed with respect to

ambient currents, to simulate varying conditions in the ocean environment

(Table 8-3).

Table 8-3 Current parameter values and wave climate for modelling scenarios for the seawater concentrate plume

Current Modelling scenario Direction

(°) Velocity (m/s)

Waves

1 149 0.02 No wave action modelled




Current Modelling scenario Direction

(°) Velocity (m/s)

Waves





8 149 0.02 5 metre height, 12 second period




8.2.4 Results

Ecotoxicity

Concentrate discharged into the marine environment would contain a range of

constituents that would initially be present at higher concentrations than

naturally found in the marine environment.

The toxicity testing calculated that to protect 99 per cent of marine species

(from sub-lethal chronic toxic effects) a maximum dilution of 30:1 would be

required (using a conservative acute to chronic ratio of 2.5 and EC10: the

concentration of material in water that is estimated to cause a response in

10 per cent of the test organisms or the mean response of the organisms differs

from the control by 10 per cent)(refer to Hydrobiology and CSIRO, 2008 for

more information).


A literature review of the effects of salinity on some plankton is provided in

Hydrobiology and CSIRO (2008) Technical Appendix 24. A study in 1986 found

that over the course of 16 days (at 30°C), larvae of the hermit crab (Pagurus criticornus) grow and metamorphose equally well in 25 and 35 psu, but at

45 psu fewer larvae progressed beyond their second development (about 5

days). A study in 1992 investigated the toxicity of mixes of concentrate from

various desalination plants and seawater. Bioassays used were 48-hour spore

germination and germ tube length using the giant kelp (Macrocystis pyrifera),

10-day survival test using amphipods (Rhepoxynius abronius) and 48-hour

fertilisation test using the sea urchin (Strongylocentrotus purpuratus). No effect

was observed for any of these tests over a range of salinities up to 43 psu.

Water quality

Based on the design for the Reference Project, the estimated composition of the

Desalination Plant discharge (prior to dilution) is presented in Table 8-4 (GHD

20083 Technical Appendix 23).

Table 8-4 Estimated composition of the Reference Project Desalination Plant discharge prior to dilution

Parameter Units Reference Project estimated discharge

Physiochemical parameters

TSS mg/L 0-1

TDS (by calculation from ions) g/L 61-64

Major ions

Chloride mg/L 33 200 – 35 100

Sulfate mg/L 4 800 – 5 100

Bromide mg/L 100 - 110

Fluoride mg/L 1.5 - 1.6

Calcium mg/L 690 - 730

Magnesium mg/L 2 300 – 2 400

Sodium mg/L 18 800 – 19 800

Potassium mg/L 800 - 850


Parameter Units Reference Project estimated discharge

Total barium mg/L 10

Total boron mg/L 7 - 8

Total strontium mg/L 13 - 14

Total metals

Aluminium µg/L 22

Iron µg/L 30 - 72

Arsenic (total) µg/L 1 - 2

Cadmium µg/L 0.1 - 0.2

Chromium (total) µg/L 0.3

Copper µg/L 0.2

Lead µg/L 0.3

Manganese µg/L 0.8 - 0.9

Mercury µg/L 0.1

Molybdenum µg/L 16 - 18

Nickel µg/L 0.3

Tin µg/L 2.7- 2.8

Zinc µg/L 2 - 3

Nutrients

Ammonia mgN/L 0.01-0.02

Nitrite + Nitrate mgN/L 0.01

Total nitrogen mgN/L 0.3

Soluble reactive phosphorus mgP/L 0.003-0.005

Total phosphorus mgP/L 0.02

Organic compounds

Total organic carbon mg/L 2

Source: GHD 20083


Elevated salinity is not considered a toxicant under the Australian and New

Zealand Guidelines for Fresh and Marine Water Quality as it readily degrades in

the marine environment. However, salinity changes the chemistry of the aquatic

environment, which may have detrimental effects on marine biota. Potential

effects of higher salinity include:

• short-term impacts on survival and metabolic function due to osmotic

effects as the elevated concentration could result in the dehydration of cells

• long-term, chronic effects on the structure of the marine community due to

changes in the ability of particular species to compete and avoid predation

within the marine ecosystem.

The dilutions required for the estimated Reference Project discharge was

calculated based on the estimated discharge constituent concentrations

(Table 8-4), adopted trigger values, and the ambient constituent concentrations

(from water quality sampling discussed in section 4.5). For all the parameters,

the dilution requirement is less than 20 times to meet the trigger values

(GHD 20083, Technical Appendix 23).

The range for parameters for the Reference Project discharge includes

consideration of the infrequent discharge of the pre-treatment supernatant to

the ocean with the RO concentrate.

The toxicity assessment found that there was no significant difference between

solutions containing process chemicals and the adjusted seawater solution.

This indicates that salinity is the primary, but not the sole, driver of toxicity.

Given the engineering dilution and short exposure time for marine organisms, it

is highly unlikely that acute toxicity would occur within any mixing zone due to

the process chemicals.


Hydrodynamic modelling

The available information and ecotoxicity tests indicate that biota are likely

to be resilient to exposure to short-term high salinity and longer-term low

salinity. The conservative estimate of tolerance from the ecotoxicity tests was

that no chronic effect was expected on biota at salinities less than 1 psu above

the ambient salinity. Spatial salinity variations of up to 2 psu have been

measured offshore from Phillip Island in January. Hence, the use of 1 psu as a

guide to determining an extent of possible chronic effect on marine biological

community is a reasonable guideline.

Hydrodynamic modelling estimated the dilution and dispersion of the

concentrate from the Reference Project for a range of climatic conditions.

The near-field modelling simulates discharge of the concentrate from the outlet

nozzle upward in to the water column. The initial velocity of the concentrate is

predicted to be in excess of six metres per second. For an ambient salinity

concentration of 35 psu, the model predicts rapid dilution to 40 psu in two

seconds and then dilution of 1 psu of regional ambient salinity in 60 to 100

seconds (Figure 8-6). The figure illustrates the high levels of dilution achieved in

the turbulent (jet) mixing zone. Mid-field modelling shows that the plume would

then move towards the seabed and predicts the likely behaviour of the plume

beyond the near-field.


Figure 8-6 Salinity versus time exposure for each of the four jets on a single rosette

Modelling results for eleven scenarios (presented in Table 8-5) show

considerable variation in the seabed area with at the boundary of which values

of salinity are 36.5 psu.

Table 8-5 Mid-field modelling results

Scenario Area of seabed (hectares) greater than 36.5 psu

1 0.44

2 0.31

3 0.44

4 1.69

5 0.13

6 0.06

7 1.88

8 1.38


Scenario Area of seabed (hectares) greater than 36.5 psu

9 0

10 1.81

11 0

Source: ASR 20087

With reference to the above:

Scenario 2 represents common conditions in the Project area (with a

0.05 metres per second longshore current moving in an approximately

south-south-easterly direction). This modelling predicts that the concentrate

would disperse from the outlet, away from shore.

Variations in oceanic conditions at the Project area would influence the

behaviour of the concentrate. Comparison between Scenario 4 (no wave action)

with Scenario 9 (same current as Scenario 4, but 5-metre high, 12-second

period waves) shows that higher wave action results in lower salinity as wave

action mixes the plume of seawater concentrate through the water column.

For Scenario 5, the largest current modelled (0.3 metres per second moving in

an approximately south-south-easterly direction), modelling predicts that the

current elongates the salinity plume in the direction of the current, resulting in a

diluted plume extent. Similarly, Scenario 11 shows the elongation of a plume in

a north-north-westerly direction due to a north-north-west current (at

0.1 metres per second).

The modelled scenarios show that the intake flow is unlikely to be affected by

the discharge from the outlet. Only Scenarios 7 and 11 show a minor increase in

salinity of 0.1 and 0.2 psu respectively. Typically, the strong flow around the

outlet would quickly move the discharge stream away from the intake area.

Additionally, much of the higher salinity water from the outlet would flow

beneath the intake, away from the intake stream. Even in the worst-case

scenario (i.e. no wave action), although the intake head may at times be in the

area of slightly elevated salinity, the discharge would tend to sink by its own

mass towards the seabed away from the intake stream.


Discharge-induced recirculation currents (driven by density differences) may

also occur in periods of prolonged low current. The modelling shows that

recirculation currents would generally be less than 0.2 metres per second (ASR

20087 Technical Appendix 29). Predicted currents would be less than 0.08

metres per second beyond 500 metres shoreward and longshore from the

outfall, with stronger currents (up to 0.2 metres per second) that would extend

offshore from the discharge along the seabed. Salinity within the recirculation is

expected to be generally below 1 psu, except within the proximity (hundreds of

meters) of the point of discharge (CEE 2008, Technical Appendix 31).

Zones where the salinity is greater than or equal to 36.5 psu occur in several

locations across the model extent. An indication of the size of the zone is shown

in Table 8-5. The modelling shows that these patches occur at small, variable

locations within a greater area. Patches would move with tide, wind and wave

influence.

In summary, the modelling indicates that:

Near-field dilution (in most cases 1:50 or better) would be achieved in the

water column typically within a distance of 100 metres.

During calm conditions, elevated salinities (i.e. in the order of 1 to 2 psu

above ambient) would occur on the seabed beyond the near-field zone,

but within a distance of the order of 500 metres.

Large areas of seabed would not be continuously exposed to salinity levels

exceeding 36.5 psu (i.e. +1 psu above ambient). Table 8-5 (ASR 2008

Technical Appendix 29) indicated areas ranging in size from 0 to 1.8

hectares where salinity exceeds 36.5 psu. The area quoted represents the

cumulative total of several ‘patches’ of salinity.

Although the remnant plume would likely sink to the seabed upon release

from the outlet, and continue to sink under gravity (which acts in an

offshore direction), the plume would tend to spread across the seafloor

influenced by the seabed slope and current direction. In general, this

movement is away from the high profile reef and will continue to dilute

the plume.

In many of these locations, whilst the peaks could be of the order of 2 psu

above ambient, it is expected they would be closer to 1 psu above ambient.


The areas that are exposed to these salinity levels would vary in size,

duration and location and are likely to be patchy rather than continuous.

Where waves are of sufficient size, wave action can lower seabed salinity.

Seawater concentrate plume dynamics are essentially unaffected by the

presence of the Desalination Plant intake.

8.2.5 Process for determining the mixing zone

The mixing zone determined for the Project would be a specific area

surrounding the outlet. For the Reference Project, a “safe dilution” has been

derived which must be met at the boundary of the mixing zone. This is based

on:

• a safe dilution factor of 30:1 derived from the ecotoxicity testing

• a safe dilution factor of 20:1 derived from comparison of concentrate

chemical constituents with water quality trigger values.

At this safe dilution (30:1) a salinity of 1 psu above background is acceptable

and this (or any higher figure agreed with the EPA) would form the boundary of

the mixing zone. It is not possible at this stage to state the statistical occurrence

of elevated salinity on the seabed between a distance of 100 metres and 500

metres under infrequent calm conditions. However, longer modelling duration

runs during the design phase would allow a firmer statement of what distance

between an estimated 100 metre and 500 metres is the most appropriate

boundary for a mixing zone. However, on the basis of the Reference Project

design, it can be concluded that the engineering design is a good or better

dilution than other desalination plants in Australia and is combined with a PR for

the mixing zone that ensures the SEPP (WoV) requirements would be met.

8.2.6 Impact assessment – Discharge

This section discusses the potential impacts of operation of the outlet structure

on the marine environment. Both the risk assessment and the impact

assessment recognise that, like the Reference Project, the Project must comply

with the Performance Requirements set out in Chapter 11 of Volume 1.


Risks assessed as medium or above

Table 8-6 sets out the risks associated with operation of the outlet which were

rated medium or above.

The following discussion is applicable to the Marine Structure Variations as well

as the Reference Project. Pipeline style diffusers are considered one Variation in

the Reference Project. This style of diffuser can be engineered to meet near-

and mid-field safe dilution requirements. It is considered highly likely that this

Variation in the diffuser design could be designed to comply with the safe

dilution and mixing zone requirements discussed further in this chapter.

Table 8-6 Risks from operation of the outlet assessed as medium or above

Activity Impact pathway C

onse

quen

ce

Like

lihoo

d

Ris

k

Discharge of saline

concentrate

Flow on effects from saline concentrate discharge – impact

on ecosystem interactions

Minor Likely Medium




Biota on the seabed close to the discharge would experience greater ranges in

salinity concentrations and more variable salinity than those further from the

discharge. Biota on the boundary of the area affected by elevated salinity (far

field) may experience prolonged periods of relatively low elevations in salinity.

The concentrate plume is not likely to reach the Marine Park, National Park and

Coastal Reserve.

Spring is generally considered to be the period of highest biological activity.

Dilution of the saline concentrate discharge is likely to be seasonal, with high

dilution during spring due to oceanic conditions. Overall, therefore, the

occurrence of high currents during the general period of peak biological activity

would tend to mitigate the extent and potential effects of elevated salinity on

many sensitive life stages in the region of the discharge (CEE 2008, Technical

Appendix 31).


Given the range of salinity within the mixing zone predicted by hydrodynamic

modelling, planktonic and pelagic species are likely to only be exposed for

minutes of their life. There may be some effects on a small proportion of the

planktonic component exposed to the concentrate close to the nozzles. Pelagic

species are unlikely to be detrimentally affected by the concentrate because

they would likely be exposed for only a short period (seconds) to the dilute

saline concentrate.

Benthic species that inhabit the seabed may experience greater exposure to

slightly elevated salinity in patches under some calmer conditions as

demonstrated by the mid-field modelling. These patches would generally occur

offshore of the high-relief reef as the plume tends to move offshore. In general,

the concentrate is not expected to have an effect on marine biota outside the

mixing zone.

It is possible that some long-term effect of the concentrate may be expressed in

changes to the species composition and abundance of the benthic marine

community within the mixing zone. Effects could be expressed as the decreased

ability of some biota and species to ecologically compete with others, or to avoid

predation as a consequence of long-term, small changes to the salinity regime

of the area around the outlet. However, biota outside of the mixing zone would

not be affected by the concentrate and beneficial uses would be protected

outside of the mixing zone.

The long-term impact of a desalination discharge on the marine community

likely depends on a number of site-specific characteristics. For example,

discharge of a saline concentrate (approximately 68 psu) in four metres of water

along a high-energy coastline in Spain found shifts in the community structure

close to the outlet, but similar biological impacts were not detectable beyond the

outlet. Similarly, changes to the benthic community were detected within 200

metres of the discharge of a desalination plant in Cyprus. This shift in

community structure may be due to loss of some sensitive species such as

echinoderms. Other research, however, has not detected significant changes to

marine fauna (CEE 2008, Technical Appendix 31).


Indirect effects may occur as a result of competitive ecological interactions

between species disadvantaged, advantaged and unaffected by exposure to low

and variable concentrations of saline concentrate. Research from other

desalination plants provides an indication of the range of response in the marine

environment to a concentrate discharge. Effects may be expressed as changes

to the hard seabed community with some species becoming more abundant

while others are less abundant. The magnitude of this community change is

uncertain but likely to be initially established in an area near the structure over

the first five years of operation. This may have flow-on effects to other parts of

the ecosystem as ecological processes such as predation and competition may

be affected (CEE 2008, Technical Appendix 31).

In summary:

The PRs require an engineering design dilution target of at least 50:1 into

the local ambient water column within 100 metres of the diffuser(s) under

all design flow conditions.

The PRs set a target of 1 psu (or as agreed by EPA) above regional salinity

levels, with 95% confidence limits on an annual basis, outside the marine

sensitivity area outlined in Figure 2-5 of this volume. This will provide

protection to the marine sensitivity areas.

As required by the PRs, further modelling, ecotoxicity testing and water

quality assessment would be done to establish the final mixing zone for

the Project Company’s design with the final mixing zone to be approved by

the EPA.

There will be impacts on some biota within the mixing zone. Biota close to

the discharge would be exposed to greater ranges as salinity generally over

shorter periods while those on the margins of the mixing zone would be

exposed to lower salinity potentially over a longer term.

For the benthic community, effects could be expressed as the decreased

ability of some biota and species to ecologically compete with others, or to

avoid predation as a consequence of long-term, small changes to the

salinity regime of the area around the outlet.

The concentrate plume is not likely to reach the Marine Park, National Park

and Coastal Reserve.


Risks assessed as low

The risk assessment for the Reference Project explored a comprehensive list of

potential environmental effects in order to identify the priority areas for

management and mitigation. The following risks have been assessed as low and

are expected to have a minor or negligible effect on the environment with


Physical effects of outlet jet stream on marine biota

The diffuser nozzles would discharge the concentrate at a velocity of around six

to seven metres per second, but modelling indicates that the velocity of the

outlet stream would rapidly slow upon entering the marine environment. Under

these conditions the consequence of physical damage to marine biota from the

jet stream at the modelled velocities is considered to be negligible.

Discharge currents

Discharge-induced recirculation currents may also occur in periods of prolonged

low current. Most non-passive larvae are likely to be unaffected by the

discharge-induced recirculation currents, which are within the range of average

currents that are experienced on many parts of the Victorian coast beyond

Kilcunda and Cape Paterson. Hence, non-passive larvae are likely to be capable

of maintaining their preferred pathways over most of the recirculation area,

particularly close to the seabed in areas of high relief reef where reef outcrops

and kelp reduce currents. Short duration, passive larvae in the vicinity of the

discharge may be affected by these recirculation currents. These may be

transported offshore or onshore depending on their position in the water column

and the duration of the recirculation pattern.


Concentrate temperature

Seawater taken into the Plant would be discharged at a slightly elevated

temperature due to the desalination process. The concentrate is expected to be

approximately 1°C elevated above ambient seawater. Modelling of the

concentrate was conducted for a range of temperatures (intervals of zero to six

degrees above ambient). The results show that temperature does not play a

significant role in the behaviour of the concentrate discharge and dilution is

nearly the same for all temperatures tested. In general, the combination of

mixing and thermal energy transfer would be faster than the salinity diffusion

process (ASR 20088, Technical Appendix 30).

8.3 Combined effects of operation of the Marine Structures

Although this assessment has considered the intake and outlet separately,

marine biota would be influenced by the combined effect of both Marine

Structures. Major effects would include entrainment, exposure to the discharge

and (to a lesser extent) attraction to the structures. The effects of the outlet

would be greater in magnitude in the mixing zone (in terms of community

structural change) but effects of the intake would be more widespread and

subtle. Mid-field impacts of the intake and outlet are likely to overlap, and there

may be a cumulative effect on marine ecosystems as organism could experience

a combined effect of both structures in the zone of overlap.

Plankton are likely to be affected by both entrainment and the concentrate. The

concentrate could affect a small proportion of plankton that are in contact with

the discharge close to the intake, although individuals are only likely to be

exposed to the concentrate at higher concentrations for short periods of time.

Entrainment is most likely to be detectable for short duration larvae. These are

typically larvae from benthic species, although some significant reef species,

such as abalone, have larvae that disperse in proximity to their area of release.

In general, the estimated number of plankton likely to be affected by the intake

and outlet would be small relative to the regional populations and any effects on

the plankton community are likely to be small and very localised (CEE 2008,



The pelagic community is likely to be unaffected by the intake due to design

features that minimise the intake water speed and the bar screens at an

appropriate distance to preclude marine biota, as specified in the Reference

Project. Some larvae of pelagic species may be entrained in the intake, but

these larvae and eggs are generally widely dispersed and the effects on the

regional larvae population are likely to be small. The discharge may affect some

individuals, but there are unlikely to be long-term impacts on fish populations as

exposure times are likely to be short-term.

The benthic community is more likely to be affected by the intake and outlet.

The concentrate may affect community composition within the mixing zone due

to some longer-term effects of elevated salinity; some benthic larvae would be

entrained in the intake system. The benthic community may be modified but it is

expected that many species would be retained and marine growth would remain

abundant in the Project area. Combined effects on the benthic community are

likely to be within the immediate area of the outlet and within the mixing zone.

Any potential effects of entrainment on the benthic community would likely be

detectable close to the intake. It is possible that a biological gradient would

establish in the mid-field area over the duration of the project. In the first five

years, changes are likely to be more pronounced in the vicinity of the Marine

Structures and become decreasingly apparent at a distance of two kilometres.

Since the effects on this community (and other marine communities) would be

concentrated near the Marine Structures, it is likely that there would be no

detectable effect on marine community structure at the nearby marine parks or

other neighbouring sensitive marine environments.

The Performance Requirements have been developed to minimise, to the extent

practicable, the impacts on marine flora and fauna from Project activities, to

limit entrainment of marine biota and to comply with SEPP (WoV). The PRs

encompass a number of design features specifically targeted to achieve these

Performance Criteria including 100 millimetre by 100 millimetre grill spacing to

preclude entry of penguins and other diving birds and a minimum engineering

design dilution target of at least 50:1 into the local ambient water column within

100 metres of the diffuser(s) under all design flow conditions.


The PRs specify additional confirmation of environmental impacts to ensure

compliance with SEPP (WoV). For example, ecotoxicity testing and an water

quality assessment shall be undertaken to confirm that representative

concentrate meets the requirements of SEPP (WoV) 99 per cent ecosystem

protection. Additionally, modelling and field sampling would be required to

ensure and demonstrate that there would be no significant disruption to the

natural passage of planktonic biota by operation of the intake and outlet

consistent with maintenance of beneficial uses required under SEPP (WoV). A

mixing zone would be determined in agreement with the EPA, and monitoring

would be implemented to demonstrate protection of beneficial uses. (The PRs

are provided in detail in the next section.)

8.4 Other impacts assessed

This section discusses the potential impacts of operation of the Marine

Structures not strictly applicable to the intake and outlet. Both the risk

assessment and the impact assessment recognise that, like the Reference

Project, the Project must comply with the Performance Requirements set out in

Chapter 11 of Volume 1.

8.4.1 Risks assessed as medium or above

Table 8-7 sets out the risks associated with operation of the outlet which were

rated medium or above. The risks are discussed in order of activity and

likelihood with those most likely to occur discussed first.

Table 8-7 Other risks from operation of the Marine Structures assessed as medium or above


Con

sequ

ence

Like

lihoo

d

Ris

k

Operational exclusion

zone

Impact on commercial fishing activities through restricted

fishing areas

Minor Likely Medium





There is a possibility that the exclusion zone could preclude some commercial

marine activities or the operation of the Marine Structures could affect

commercial fishing. However, impacts on the industry are expected to be minor

due to the expected small area of the operational exclusion zone and the

minimal proportion of larvae expected to be entrained by the intake. According

to ABS census data (Essential Economics 20082, Technical Appendix 11), there

are 30 to 40 jobs out of a population of around 10 000 that are associated with

the commercial fishing industry. The aquaculture and fishing industries are very

small with respect to total business and employment in the area (less than one

per cent), so any potential impacts would be minor and could only affect a small

proportion of employment in the region.

8.4.2 Risks assessed as low

The risk assessment for the Reference Project explored a comprehensive list of

potential environmental effects in order to identify the priority areas for

management and mitigation. The following risks have been assessed as low and

are expected to have a minor or negligible effect on the environment with


Marine pests introduced during operation

Vessels involved with operations of the Marine Structures may introduce marine

pests within the Project area through introduction of ballast water, sediment and

biofouling. Introduction of pests and disease is considered improbable since a

range of controls that would be employed would reduce the risk of translocation

of marine pests. Operations vessels would be required to adhere to National and

Victorian legislation related to introduced species. Even with appropriate

controls in place, it is possible that marine pests would be transported to the

area at some stage; however, it is unlikely that the translocation of marine pests

to the area would be solely due to operation of the Desalination Plant.


Visual amenity

It is possible that operation of the Marine Structures would affect visual amenity

of the area if the discharge were visible on the ocean surface. However, near-

field modelling verifies that the jets of seawater concentrate from the Reference

Project would not be visible at the water surface (ASR 20088 Technical

Appendix 30).

Exclusion zone affecting recreational activities

A small, permanent exclusion zone would be located above the Marine

Structures during operation. Such an exclusion zone is an important safety

measure both for public safety and for protection of the Marine Structures. No

recreational or commercial activities would be permitted in the exclusion zone.

As the marine exclusion zone is likely to extend only around the underwater

Marine Structures, any social impact is likely to be negligible with no lasting

effects on recreational use of the area (Maunsell 20085, Technical Appendix 56).

Eco-tourism

Penguin and seals are the main wildlife visitor attractions in Bass Coast Shire,

although there is also some bird watching and occasional whale spotting.

Operation of the Marine Structures is not expected to affect marine biota

outside the vicinity of the Marine Structures (Biosis Research 20082, Technical

Appendix 13). Therefore, it is unlikely that the eco-tourism industry would be

adversely affected by the Project and eco-tourism operators are not likely to

experience a downturn in business due to the Project. Any effects of the Project

on eco-tourism would likely be restricted to the Project area with no effect on

operators on Philip Island who are responsible for a large amount of

employment and economic activity (Essential Economics 20082, Technical

Appendix 11).


8.5 Performance Requirements for operation

Performance Requirements (PRs) have been developed to provide an

environmental framework for managing potential impacts of Marine Structures

during operation. The PRs are focussed on the environmental ‘outcomes’ that

the State wishes to achieve through the Project delivery. The PRs relevant to

the operation of Marine Structures are set out below. The full suite of PRs for

the Project is provided in Volume 1 Chapter 11 as part of the overall

Environmental Management Framework.

As part of the environmental impact and risk assessment process relating to

operation of the Marine Structures, Bassett (2008, Technical Appendix 22), CEE

(2008, Technical Appendix 31), GHD (20083, Technical Appendix 23; 20084,

Technical Appendix 27), Hydrobiology and CSIRO (2008, Technical Appendix 24)

and Maunsell (20085, Technical Appendix 56) have identified a range of

suggested management measures that could be implemented to manage

potential impacts. These suggested management measures have been

formulated in response to the Reference Project and relevant Variations for the

Marine Structures. In effect, the suggested management measures demonstrate

how the Reference Project and relevant Variations can achieve the PRs. These

detailed management measures have formed an important input to the PRs for

the Project.

The management measures suggested by Bassett (2008), CEE (2008), GHD

(20083, 20084), Hydrobiology and CSIRO (2008) for the mitigation of impacts

associated with the operation of the Marine Structures address:

• Locating the Marine Structures in relation to marine environmental and

ecosystem conditions to avoid areas of:

- localised high productivity (primary or secondary)

- high larval production, high larval transport or high larval settlement

- upwelling

- conservation or high biodiversity value

- significance to protected or threatened species

• Minimising the effect on regional commercial fisheries by positioning the

Marine Structures away from key abalone kelp reef habitat and at least four

metres above the seabed


• Considering the position and design of the intake structure to minimise

potential ecological and marine biological impacts of entrainment and

impingement by:

- locating structures in deeper water reducing the proportion of the

water column entrained at any one intake position

- designing the intake water stream horizontal to the seabed so that

fish can sense the water current

- designing the intake velocity to less than 0.15 cubic metres

per second

- installing appropriate grills and spacings at no greater than

100 millimetres by 100 millimetres in any one direction, then spaces

no greater than 50 millimetres in any other direction

• Considering the position and design of the outlet structure to minimise

potential ecological and marine biological impacts by:

- designing the discharge to produce maximum achievable initial

dilution as close to the point of discharge as practicable

- locating outlet structures to avoid areas of high relief reef

• Developing and implementing marine ecosystem monitoring program during

operation that:

- ensures compliance with the SEPP (WoV) and potential licence

conditions

- determines the extent and level of impact of the discharge and intake

effects

- assesses the short and long term impacts of discharge on marine flora

and fauna

- document the condition of the high relief reef ecosystems

- monitors the potential acute effects of entrainment on benthic biota

- include sufficient sampling sites to determine potential tidal and

spatial patterns in suspended solids concentrations, and potential

stratification of suspended solids in the water column

- includes phytoplankton sampling to determine the contribution of

phytoplankton to suspended solids as well as provide information

spatial and temporal variation in this important biological component


• Develop a program that monitors the location and breeding success of

Hooded Plover along Williamsons Beach to better understand the impacts

on the species as the project progresses.

The PRs proposed for the marine environment are outlined in Table 8-8.

Table 8-8 Performance Requirements

Timing Subject


Coastal

Processes

Protect coastal

processes. Minimise impacts on sand

movements, wave patterns

and currents.


Demonstrate through modelling of hydrodynamic

processes such as tides, currents, winds and sand

movements, that the Project will have no adverse

effect on coastal processes.


on coastal processes.

Detail the measures proposed to address the

results of the monitoring undertaken to achieve

compliance with the Performance Criteria.

Coastal

Integrity

Protect the

physical

integrity of the

dune system,

beach and

intertidal zone.

No surface disturbance of

the dune system, beach and

intertidal zone.

No measurable loss to the

integrity of the coastal

assets including the dune

system, beach and intertidal

zone.







Minimise access outside public access pathways


on the dune system, beach and intertidal zone.

Coastal Flora

and Fauna

Protect the

ecological

values of coastal

habitat.

No reduction in habitat

values for significant

species.

Minimise loss of significant

species’ individuals.

No removal of coastal

vegetation.







Implement management measures to minimise

access of construction personnel to Williamsons

Beach and foreshore reserve, particularly during

Hooded Plover breeding season (August to

February)

Collaborate with Parks Victoria and DSE to


Timing Subject


achieve additional protective measures such as

fencing off portions of the beach used by

nesting Hooded Plovers to exclude people,

uncontrolled dogs and increased fox and cat

control

Ensure that external lights are kept to a

minimum, that they are positioned as low to the

ground as is practicable and that they are

shielded to avoid light spill upward and toward

the foreshore, beach and sea

Implement a program of monitoring the

locations and breeding success of resident

Hooded Plovers along Williamsons Beach to

measure the impact of Project Activities and

inform opportunities for mitigation. This should

continue at least monthly from prior to

construction until the plant is in routine

operation.

Implement a program of monitoring for the

Orange-bellied Parrot from March to September

prior to and during construction activities and

inform opportunities for mitigation.

Marine Flora

and Fauna –

General

Protect marine

flora and fauna.

No significant

impact on

Bunurong

Marine National

Park and on the

protected values

of marine parks.

Minimise to the extent

practicable the impacts on

marine flora and fauna from

Project Activities.

Limit impacts on ecology of

high relief reef.


management systems to protect marine flora and

fauna.

Trenching is not permitted in the designated areas

presented in Figure PR Sensitivity Area – Marine

Area, in Technical Appendix 5.

Manage any geotechnical investigation program to

avoid significant impacts on the high relief reef in

the designated area and marine fauna in general.

Marine Flora

and Fauna –

Intake

Minimise

impacts on

marine flora and

fauna from

intake structure.

Minimise impact

on Bunurong

Marine National

Park and on the

protected values

of marine parks.

Prevent entry of penguins

and other diving birds into

the intake structure.

Limit entrainment of marine

biota.

Comply with Performance Criteria.

Provide an external grill space no greater than

100 mm x 100 mm or, if the grill space is greater

than 100 mm in any one direction, then the space

should be no greater than 50 mm in any other

direction. Alternatively implement other measures

to achieve the Performance Criteria.

Locate and design intake structure:

To not significantly affect the beneficial uses

associated with the designated areas of high

relief reef and coastal reserve presented in

Figure PR Sensitivity Area – Marine Area, in


Timing Subject


Technical Appendix 5

To achieve a horizontal velocity of less than

0.15 m/s (during still conditions) or any other

measure demonstrated to achieve the

Performance Criteria

So that the lowest point of intake area is at

least 4 metres above surrounding seafloor level

Demonstrate through hydrodynamic modelling of

intake structures and behaviour that the Project

will limit entrainment to meet Performance

Criteria.

Monitor and report on possible effects of

entrainment on marine biota and demonstrate

compliance with the relevant Performance

Criterion.

Marine Flora

and Fauna –

Outlet

Minimise

impacts on

marine flora and

fauna from

siting and

operation of

Outlet structure.

Minimise impact

on Bunurong

Marine National

Park and on the

protected values

of marine parks.

Minimise impact

on ecosystem

integrity.

Comply with State

Environment Protection

Policy (Waters of Victoria).

No observable accumulation

of solid matter or staining

on the beach.

Comply with Performance Criteria.

Meet the requirements of the EPA with regard to

the Works Approval Application and Discharge

Licence.

Achieve a minimum engineering design dilution

target of at least 50:1 into the local ambient water

column within 100 metres of the diffuser(s) under

all design flow conditions.

Define an area to be approved by the EPA which

at its boundary achieves not more than 1 psu (or

as agreed with the EPA) above regional ambient

salinity, 95% of the time on an annual basis,

outside the designated areas presented in Figure

PR Sensitivity Area – Marine Area, in Technical

Appendix 5.

No discoloration of the sea surface visible from

land due to surface strike of the plume(s).

Develop and implement a monitoring program to

demonstrate performance of the Project in

operation for the protection of beneficial use that

will:

Demonstrate protection of beneficial use

outside the areas to be approved by EPA

Assess the extent, magnitude and level of

impacts of discharge on marine flora and fauna

Assess the long term impacts of outlet

discharge(s)


Timing Subject


Document condition of high relief reef

ecosystems

Demonstrate through modelling that the projected

operation will meet the Performance Criteria.

Conduct tracer testing to demonstrate compliance

of the marine structures with the Performance

Criteria.

Direct Toxicity Assessment (DTA) and water

quality assessment shall be undertaken to confirm

that representative concentrate (which contains

representative chemical additives) meets the

requirements of the State Environment Protection

Policy (Waters of Victoria) environmental quality

objectives of 99% ecosystem protection for

largely unmodified aquatic ecosystems.

Marine Amenity

– Recreational

Minimise

disruption to

marine

recreational

activities.

Outside any marine

exclusion zone (for diving

safety) no significant impact

on diving, surfing,

recreational fishing or

marine boating activities.

Limit disruption to divers

outside construction

exclusion zones.



management and systems to minimise disruption

to recreational activities.

Turbidity or colouration impacts from the outlet

should not be visible from the shoreline.

Commercial

Fishing and

Marine Tourism

Minimise

disruption to the

commercial

fishing industry

and marine

tourism.

Minimise restrictions on

commercial fishing and

marine tourism activities.



management systems that seek to achieve

effective consultation and communication with the

commercial fishing and marine tourism industry in

relation to potential restrictions and disruptions

during construction.

Marine Pests

Avoid the

introduction,

spread and

establishment of

marine pests.

Compliance with the

Commonwealth and State

legislative requirements for

Ballast Water.


Develop and implement a marine pest risk

management and monitoring process (including a

process directed to addressing the risks of

introducing pests by vessels and equipment).

Develop and implement a risk management

process specifically for limiting risk of abalone

disease.

Underwater

Noise and

Vibration –

Ecological

Protect

cetaceans.

Compliance with EPBC Act

Policy Statement 2.1 -

Interaction between



Conduct geophysical survey of Project Activities in

accordance with the procedures outlined under

th EPBC A t P li St t t 2 1 I t ti


Timing Subject


Ecological


and whales.

the EPBC Act Policy Statement 2.1 - Interaction

between offshore seismic exploration and whales.

Underwater

Noise and

Vibration –

Marine Diving

Activities

Protect marine

diving activities

from

underwater

noise and

vibration.

No significant impact

outside any marine

exclusion zone on marine

diving activities.


Outside any exclusion zone, minimise exposure of

marine recreational users to underwater

(continuous) noise levels greater than 145 dB re

1µPA.


management systems that ensure effective

consultation and communication with marine

divers in relation to marine noise and vibration.

Marine –

Navigation

Protect coastal

access on

marine waters

for vessels.

Minimise impact on safe

passage of non-Project

vessels along the coast.


Identify and implement any requirements for

notifications for vessel movements by Marine

Safety Victoria.

9.0

Su

mm

ary

of e

ffects o

f ma

rine

structu

res

9.0 Summary ofeffects of marine

structures

Chapter 9 Summary of environmental effects 9-1

9 Summary of environmental effects

The Desalination Project would require long-term placement of Marine

Structures designed to intake seawater and discharge the saline concentrate

from the desalination process to the marine environment. For a fully operational

200 gigalitre per annum Desalination Plant, the seawater intake would remove

480 gigalitres per year of seawater and the outlet would exude 280 gigalitres

per annum of saline concentrate. The Marine Structures would be located

offshore and, in the Reference Project, would connect to the Desalination Plant

via underground tunnels.

9.1 Assessment methodology

The key effects of the Marine Structures were identified taking into account

legislative and policy obligations, community and stakeholder concerns and

guidance from the Scoping Requirements. Environmental effects from

construction and operation of the Marine Structures were considered through a

risk and environmental impact assessment.

Performance Requirements (PRs) govern the Project for EES purposes, and set

the environmental parameters for the Project. The PRs are incorporated into the

Environmental Management Framework and embody the recommendations for

environmental management arising from the environmental impact and risk

assessment process. Conceptually, a Project that complies with the PRs would

fall within the EES assessment and approvals regardless of the physical

configuration of the Project.











Technical Appendix

Chapter 9 Summary of


9-2 Chapter 9 Summary of environmental effects

9.2 Existing environment

The marine Project area is frequently exposed to strong waves and winds. Local

currents are dominated by wind driven longshore currents with low tidal

currents that typically run parallel to the coast. Water quality at the Project area

is primarily oceanic, with influences from the Powlett River and Western Port.

Water quality data from one year of monitoring indicate salinity stratification

during winter and spring and temperature stratification during spring and

early summer.

The Project area is approximately one kilometre from the Powlett River.

The estuary wetland of this river supports a number of protected species.

Two coastal protected areas and two marine parks, including Bunurong Marine

National Park, are located within twenty kilometres of the Project. These areas

protect significant marine habitat and species.

The intertidal habitat at the Project area is largely sandy beach inhabited by

infaunal species with scattered sandstone and mudstone reef platforms that

support a diverse array of flora and faunal species. Most of the subtidal habitat

in the Project area is dominated by rock reefs. The reef community is dominated

by kelp in shallower waters and red macroalgae and invertebrates in deeper

waters with increasing dominance of invertebrates in deeper waters. A variety of

reef fish live in these areas.

Plankton, pelagic animals and plants that live passively in the water column,

play an important role in the marine food chain in the Project area.

Phytoplankton abundance is low in Bass Strait relative to neighbouring waters,

while zooplankton abundance is relatively higher than over the continental shelf.

The eggs and larvae of many marine species also spend a period of their life

cycle as plankton.

Seven whale species protected under the EPBC Act (Commonwealth), three of

which are also protected under the FFG Act (Victoria) periodically traverse in the

Project area. There are three vulnerable fish species that may occur in the

region that are protected under the EPBC Act: the Great White Shark, Grey

Nurse Shark and Australian Grayling. However, Grey Nurse Sharks are unlikely

to be found in the central Bass Strait region or in the Project region, and it is

unlikely that the Project area or the Powlett River form significant habitat for the

Australian Grayling. The Great White Shark may pass through the Project area

but the area is not a key habitat or feeding ground for this species.


The Australian Fur Seal, New Zealand Fur Seal and the Australian Sea Lion are

known to inhabit Victorian waters and may inhabit the Project area. A total of 31

seabird species were recorded at the Project area, including eleven listed under

the EPBC Act or the FFG Act.

The Little Penguin, an important species in the local area, has a significant

colony on the southern shores of Phillip Island. Little Penguins are expected to

use the Project area, although less than 10 per cent of Little Penguin

movements occur toward the Project area, which is approximately 25 kilometres

south-east of Phillip Island.

Commercial and recreational fishing occurs both in the Project area and the

surrounding coastal waters. Commercial fishing operations in the Project area

target abalone, rock lobster, and finfish. The mouth of the Powlett River is a

popular area for beach fishing. Locals and visitors surf at Williamsons Beach and

recreational boating is common along the coastline encompassing the Project

area. Swimming at Williamson’s beach is less popular because the beach the

area is not patrolled.

9.3 Construction of Marine Structures

The purpose of construction will be to install the Marine Structures. In the

Reference Project, the Marine Structures would be connected to the

Desalination Plant via underground tunnels below the coastal sand dunes and

the seabed. Tunnelling ensures that the coastal dunes, the beach, the coastal

reserve and marine sensitivity areas are not affected by construction.

Self-elevating platforms (SEPs) would likely be used to construct the Marine

Structures. The SEPs would operate temporarily in the marine environment

during construction of the Marine Structures, and they would be removed after

construction is complete. Overall, construction would require some limited

seabed clearing for placement of marine equipment and seabed construction

activities. Based on the PRs, construction would limit material adverse effects on

designated marine sensitivity areas. Disturbance to the seabed and associated

biota is usually temporary during construction. Disturbed areas in the marine

environment tend to be rapidly colonised by a succession of marine biota,

usually resulting in a marine biological assemblage similar to the community that

existed prior to disturbance.


Construction marine traffic would be largely derived from the movement of

vessels to the SEPs. The temporary construction exclusion zone would be

implemented to protect public safety and this would limit interactions between

construction vessels and the public. This temporary exclusion zone could

prevent some recreational activities in the immediate area. The PRs address this

potential impact by requiring development and implementation of methods and

management systems to minimise disruption to recreational activities. Any

effects on recreational activities are expected to be temporary.

A risk assessment identified the risk of possible introduction of pests and

disease through the movement of marine vessels. For example, abalone disease

could be inadvertently introduced to the area. The PRs have been established to

avoid the introduction, spread and establishment of marine pests. The PRs

specifically require development and implementation of a risk management

process for limiting the risk of abalone disease introduction and a marine pest

risk management and monitoring process. With implementation of these

measures, it is considered unlikely that the Project would introduce the abalone

disease or any other disease or pests.

Collectively, construction activities are expected to affect the visual amenity of

the local area, as the Project may interrupt the quality of coastal views in some

areas. Any effect from construction would be restricted to a small section of the

coast and would only occur for the temporary construction period. There is a

community concern that these modifications to the visual amenity of the area

could generally change the perception of the area and lower tourist visits.

However, most tourism in the area occurs in and around Philip Island and well

away from the Project area. Therefore, visitation and eco-tourism are not

expected to be affected in the long-term from the construction activities at the

Project area.

Chemicals and hydrocarbons would be used during marine construction, largely

for vessel and equipment fuelling. These chemicals would not be placed in the

marine environment, but accidental spills could occur. Chemical spills that may

occur during the construction phase are considered unlikely to result in severe

effects on any communities or ecosystems. Notwithstanding, standard industry

procedures for control of chemicals are hydrocarbons are required as part

of the PRs.


Construction activities are also likely to create underwater noise and vibration.

Any disturbance to the local ecology is expected to affect individual fish and

benthic biota, and it is unlikely that construction activities would detrimentally

affect marine biota at the population or community level. The PRs have been

developed to address potential impacts from construction on the marine

environment and to prevent any wide-reaching or long-term effects. In

particular, the use of geophysical survey methods to investigate sub-surface

geology would be conducted in accordance with procedures outlined in the

EPBC Act Policy Statement 2.1 to minimise potential underwater noise impacts

on marine biota.

Spoil would be generated from tunnelling and drilling for the Marine Structures.

Based on the Reference Project, most of the drilling spoil would be collected on

the SEP and later taken to land for disposal, if a suitable marine spoil disposal

site cannot be identified. Any impact on the marine environment is expected to

be minimal as the PRs specify disposal of any spoil from marine construction in

accordance with EPA Best Practice Guidelines for Dredging and the National

Ocean Disposal Guidelines for Dredged Material.

Construction activities would increase the number of people working in the

Project area and this could result in more people accessing the adjacent beach

area. People can disturb Hooded Plovers nesting in the beach area by flushing

adults from active nests. Disruptions to the Hooded Plover population are

considered to be a moderate consequence due to the small Victorian population.

It is for this reason that the PRs require the implementation of methods and

management systems to ensure no adverse effects of Project activities on the

dune system, beach and intertidal zone to minimise the loss of individuals of

significant species.

In general, environmental impacts during construction are considered

manageable, and any effects are expected to be temporary with no lasting

impact on the marine environment. Risks that are certain or likely to occur

would be managed and minimised through the PRs and unlikely or rare risks

would be avoided through implementation of the PRs. Marine construction

commonly occurs throughout Australia. The accumulation of environmental

management experience would be drawn upon to minimise environmental risks

and disturbance to the marine environment.


9.4 Operation of Marine Structures

During the operational phase, the Marine Structures would serve two main

purposes: to intake water from the ocean to the Desalination Plant and to

release the concentrate from the desalination process to the ocean. In the

Reference Project, the intake would draw seawater horizontally via a mushroom

head structure that would be screened with grills on the opening. The

concentrate (roughly double the dissolved solutes of the concentrated seawater)

would be released offshore through diffusers, which would facilitate dilution and

dispersal of the concentrate into the water column. Further natural mixing

would disperse the concentrate.

To reduce potential environmental impacts, residual risks to the marine

environment have been investigated through multiple approaches. Ecotoxicty

testing explored the toxic effect of the concentrate and reverse osmosis cleaning

chemicals on indicator marine organisms. The data gathered for the Project

area’s hydrodynamic processes, water quality and ecology as well as assessment

of impacts have informed predictions of the short- and long-term expected

environmental effect on the marine environment. Dynamic processes around the

intake have been modelled and concentrate discharge has also been modelled

under a variety of hydrodynamic scenarios expected at the Project area.

The PRs undertake a commitment to avoid siting the marine inlet and outlet

structures in marine sensitivity areas that support higher biodiversity, fishing

activities and the coastal reserve that extends offshore of Williamsons Beach.

The intake has been designed to minimise the potential impacts on marine

biota. The design includes appropriate intake head grill spacings to specifically

prevent the entry of Little Penguins and other diving birds into the intake and

limit entrainment of marine biota. Low intake velocity would further limit

entrainment and entrapment of marine organisms. These design features are

required by the PRs.

Modelling has been used to estimate larval entrainment by the intake. For very

short, short and longer larval durations, modelling shows that the intake could

remove up to 1.5 per cent of the individuals from an area near the intake,

parallel to the coast. The model does not predict entrainment outside of the

areas of influence near the intake structure. The reduction in numbers of larvae

even within this zone of influence are very small considering the overall

population of these larvae present in Bass Strait and surrounding waters.


Many species have a strategy of abundant production of larvae to protect the

population from high mortality rates. Most species that produce an abundance

of larvae can have high natural mortality and still sustainably replenish adult

populations. These populations may tolerate additional small loss of larvae via

artificial uptake, such as by the intake structure, and adult populations are not

likely to be affected by this reduction in larvae. Long-term monitoring of larvae

at many Californian intakes has consistently found that the same larval species

assemblages occur over time, indicating that operation of intakes is not

significantly impacting marine organisms at the population level.

Concentrate discharged into the marine environment would contain a range of

constituents that would initially be present at higher concentrations than

naturally found in the marine environment. To estimate the toxicity of the

discharge to marine organism, ecotoxicity testing was undertaken to identify the

dilution that provide 99 per cent species protection. This result shows that

salinity was the primary, but not the only, stressor in the discharge. A “safe

dilution” of 30:1 with a salinity variation of 1 psu above ambient would meet the

ecosystem protection requirement under SEPP (WoV). The water quality

assessment showed that the maximum dilution required for any single chemical

constituent assessed was 20:1, with most requiring less dilution to meet the

requirements of SEPP (WoV).

From an ecological perspective the initial dilution and the short timeframe in

which this occurs indicates that any marine organism in the water column would

only be exposed for a short period of time, which is likely to be insufficient to

result in a toxic reaction, including osmoregulatory shock from salt exposure.

This includes plankton that may inadvertently be entrained into the plume.

Pelagic species like fish are unlikely to be affected because their exposure would

be short and no impact is expected. Benthic species that live on the seabed may

experience greater ranges in elevated salinity, especially if they are closer to the

point of discharge. This order of change may result in a shift in community

structure and is likely to be expressed as a change in the mix of species, with

some more tolerant species more abundant in areas of the seabed that may be

consistently exposed to slightly higher salt concentrations. It is predicted that

the marine community within this zone would contain many of the same plants

and animals that are presently growing there, although their proportions may

change. The extent of this community shift would be carefully monitored under

a program devised as part of the PRs.


Performance Requirements have been developed to ensure compliance with

SEPP (WoV) including achieving 99 per cent ecosystem protection for largely

unmodified aquatic ecosystems. The PRs encompass design features specifically

targeted to achieve compliance with SEPP (WoV). For example, the PRs require

a minimum engineering design dilution target of at least 50:1 into the local

ambient water column within 100 metres of the diffuser (under all design flow

conditions). The mixing zone would be agreed with the EPA which at its

boundary is to achieve no more than 1 psu (or as agreed by EPA) above

regional ambient salinity 95 per cent of the time on an annual basis outside the

marine sensitivity areas. This will provide protection to the marine sensitivity

areas. Outside of this mixing zone, there is expected to be no impact on marine

biota due to discharge of the concentrate.

The mid-field modelling report (ASR 20087) Technical Appendix 29, indicated

areas ranging in size from 0 to 1.8 hectares where salinity exceeds 36.5 psu.

The areas quoted represent the cumulative total of several ‘patches’ of salinity.

A monitoring program would be developed and implemented to demonstrate

protection of beneficial uses.

9.5 Conclusions

Although the Desalination Plant would be the largest in Australia, the Reference

Project technology for desalinating seawater is well known. Potential

environmental impacts from construction and operation of the Marine Structures

can be minimised by careful selection of engineering design, which can be

informed by knowledge of the local marine environmental conditions. The

remaining expected environmental impacts have been explored through detailed

investigations including modelling, field inventories, toxicity testing, water

quality monitoring, literature review and biological assessment. The Marine

Structures would be built in accordance with the requirements of a range of

legislation and policies that would ensure that any impacts to the marine

environment are minimised. The characteristics of the discharge would comply

with the relevant SEPPs to ensure that the environment and beneficial uses are

protected. A mixing zone around the outlet would be declared by the EPA. It is

predicted that the marine community within this zone would contain many of

the same plants and animals that are currently present, although their

proportions may change.


Operation of the Marine Structures could have some longer-term effects on

the marine environment, although the impact of both the intake and outlet

are expected to be detectable only in the vicinity of the Marine Structures.

Removal of some eggs and larvae by the intake is one likely impact of the

Project on the marine environment, but only a small proportion of larvae are

predicted to be removed by the intake. Environmental monitoring during

operation, required by the PRs, would assess the extent, magnitude and level of

impact of discharge on marine flora and fauna to minimise potential impacts on

ecosystem integrity, which is expected to be restricted to an area close to the

Marine Structures.

Performance Requirements have been developed to provide an environmental

framework for managing potential impacts of Marine Structures during

construction and operation. A suite of PRs have been developed applicable to

the marine environment to limit entrainment of marine biota, limit impacts on

the ecology of continuous high relief reef, minimise restrictions on commercial

fishing and marine tourism activities and minimise, to the extent practicable,

impacts on marine flora and fauna from Project activities. The PRs also require

activities such as modelling, management and monitoring and validate the

Project Company’s final design against PRs and requirements of the EPA.

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