GAS IMPORT JETTY AND PIPELINE PROJECT ENVIRONMENT EFFECTS STATEMENT INQUIRY AND ADVISORY COMMITTEE

TECHNICAL NOTE

TECHNICAL NOTE NUMBER: TN 007

DATE: 2 October 2020

LOCATION: Crib Point Jetty Works

EES/MAP BOOK REFERENCE: Technical Report A Response to RFI 021 – Section 2.5: Chlorine and temperature SUBJECT: discharge conditions The documents attached to this technical note are those SUMMARY completed by CEE between 2014 and 2018 and referred to in the "Reference List" of Technical Report A.

Provide links to the reports referenced in EES Technical Report REQUEST: A completed by CEE between 2014 to 2018 Annexure A-A.

NOTE:

1. We understand this request to be referring to the CEE reports listed in the reference list to Technical Report A.

Documents

2. The following documents are provided as attachments to this technical note:

(a) CEE (2014a). North Arm Subtidal Seagrass and Water Quality Monitoring. Spatial variation in subtidal seagrass depth limits in Western Port, February 2014. Report to Port of Hastings Development Authority.

(b) Appendix of CEE (2014a). North Arm Subtidal Seagrass and Water Quality Monitoring. Spatial variation in subtidal seagrass depth limits in Western Port, February 2014. Report to Port of Hastings Development Authority.

(c) CEE (2014b). Port of Hastings Seagrass Monitoring Pilot Study. Report to Port of Hastings Development Authority. CEE Melbourne June 2014.

(d) CEE (2017). Long Island point: Wastewater Discharge - AGL Gas Import Jetty and Pipeline Project. Report for AGL.

(e) CEE (2018a). Plume Modelling of Discharge from LNG Facility at Crib Point, Western Port – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

(f) CEE (2018b). Chlorine in FSRU Seawater Processes – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

(g) CEE (2018c). Assessment of effects of cold-water discharge on marine ecosystem at Crib Point – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

(h) CEE (2018d). Modelling and Assessment of Biological Entrainment – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

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(i) CEE (2018e). Marine Ecosystem Protected Matters – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

(j) CEE (2018f). Effects of LNG Facility on Sea Level and Seabed at Crib Point Jetty – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

NA CORRESPONDENCE: 10 Attachments. ATTACHMENTS:

1. CEE (2014a). North Arm Subtidal Seagrass and Water Quality Monitoring. Spatial variation in subtidal seagrass depth limits in Western Port, February 2014. Report to Port Of Hastings Development Authority.

2. Appendix of CEE (2014a). North Arm Subtidal Seagrass and Water Quality Monitoring. Spatial variation in subtidal seagrass depth limits in Western Port, February 2014. Report to Port of Hastings Development Authority.

3. CEE (2014b). Port of Hastings Seagrass Monitoring Pilot Study. Report to Port of Hastings Development Authority. CEE Melbourne June 2014.

4. CEE (2017). long Island point: Wastewater Discharge - AGL Gas Import Jetty and Pipeline Project. Report for AGL.

5. CEE (2018a). Plume Modelling of Discharge from LNG Facility at Crib Point, Western Port – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

6. CEE (2018b). Chlorine in FSRU Seawater Processes – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

7. CEE (2018c). Assessment of effects of cold-water discharge on marine ecosystem at Crib Point – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

8. CEE (2018d). Modelling and Assessment of Biological Entrainment – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

9. CEE (2018e). Marine Ecosystem Protected Matters – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

10. CEE (2018f). Effects of LNG Facility on Sea Level and Seabed at Crib Point Jetty – AGL Gas Import Jetty and Pipeline Project. Report for AGL.

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Attachment 1

Prepared for: Port of Hastings Development Authority

Port of Hastings Development Project

North Arm Subtidal Seagrass and Water Quality Monitoring

Spatial variation in subtidal seagrass depth limits

February 2014

Spatial variation in subtidal seagrass depth limits in Western Port February 2014

Contents 1 Introduction 1 1.1 This document 1 2 Scope of Work 2 3 Purpose of task 2 4 Methods 3 4.1 Sites investigated 3 4.2 Subtidal seagrass lower depth limit 4 4.3 Transects 4 4.4 Light/CTD profiles 4 4.5 Seagrass taxonomy 11 4 Zostera Lower Depth Limit site results 12 4.6 Light attenuation 13 4.7 Maximum depth limits 14 4.8 Seabed slope 14 5 Transect descriptions 20 4.9 Charing Cross 20 4.10 Quail Island 22 4.11 The Bluff 23 4.12 North BlueScope 24 4.13 Long Island Point South 25 4.14 Middle Spit 26 4.14.1 Middle Spit North 26 4.14.2 Middle Spit South 27 4.14.3 North Arm channel mark No. 1 28 4.15 Chilcott Channel 29 4.16 Stony Point North 30 4.17 Tortoise Head South 31 4.18 Corinella 33 5 Zostera nigricaulis sample Morphometrics 34 6 Summary data interpretation and Observations 36 6.1 Lower depth limit of Zostera and determining factors 36 6.2 Most extensive subtidal seagrass 37 6.3 Light requirement of Zostera seagrass 37 6.4 Intertidal seagrass 38 7 Conclusion 40 8 References 41 9 Appendix 42 10 Appendix. Preliminary site information Report. February 2014 43

Spatial variation in subtidal seagrass depth limits, January 2014 ii

Figures

Figure 1 Major geographical segments and other features of Western Port ...... 2 Figure 2 Key Maps ...... 3 Figure 3 Typical subtidal plants in Western Port ...... 11 Figure 4. Plot of Secchi disk depth versus light attenuation coefficient ...... 13 Figure 5 Depth limits for Zostera nigricaulis at sites around Western Port – January 2014 . 18 Figure 6 Light attenuation coefficients calculated during this investigation and EPA fixed sites ...... 19 Figure 7 Bathymetry and aerial image (Feb 2013) of Charing Cross transects ...... 20 Figure 8 Charing Cross Transect 1 vegetation profile...... 21 Figure 9 Charing Cross Transect 2 vegetation profile...... 21 Figure 10 Bathymetry and aerial image of Quail Island transect ...... 22 Figure 11 Quail Island transect vegetation profile ...... 22 Figure 12 Bathymetry and aerial image of The Bluff transect ...... 23 Figure 13 The Bluff transect vegetation profile ...... 23 Figure 14 Bathymetry and aerial image of North BlueScope transect ...... 24 Figure 15 North BlueScope transect vegetation profile ...... 24 Figure 16 Bathymetry and aerial image of Long Island Point South transect ...... 25 Figure 17 Long Island Point South transect vegetation profile ...... 25 Figure 18 Bathymetry and aerial image of Middle Spit North transect ...... 26 Figure 19 Middle Spit North transect vegetation profile ...... 26 Figure 20 Bathymetry and aerial image of Middle Spit South transect ...... 27 Figure 21 Middle Spit South transect vegetation profile ...... 27 Figure 22 Bathymetry and aerial image of North Arm Channel Mark No. 1 transect ...... 28 Figure 23 North Arm Channel Mark no. 1 transect vegetation profile ...... 28 Figure 24 Bathymetry and aerial image of Chilcott Channel transect ...... 29 Figure 25 Chilcott Channel transect vegetation profile ...... 29 Figure 26 Bathymetry and aerial image of Stony Point North transect ...... 30 Figure 27 Stony Point North transect vegetation profile ...... 30 Figure 28 Bathymetry and aerial image of Tortoise Head South transects ...... 31 Figure 29 Tortoise Head South transect 1 vegetation profile ...... 31 Figure 30 Tortoise Head South transect 2 vegetation profile ...... 32 Figure 31 Tortoise Head South transect 3 vegetation profile ...... 32 Figure 32 Bathymetry and aerial image of Corinella transect ...... 33 Figure 33 Corinella transect vegetation profile ...... 33 Figure 34. Possible annual light range in north of Lower North Arm Western Port ...... 37 Figure 35. Infra red photograph of tidal divide, north of ay 1977/78 ...... 39

Tables Table 1 Summary of Zostera nigricaulis lower depth limit data ...... 12 Table 2. Zostera LDL site metadata, Western Port January 2014 ...... 15 Table 3 Preliminary seagrass morphology data...... 34 Table 4 Positions of water quality profile sites (light and CTD) ...... 42

Spatial variation in subtidal seagrass depth limits, January 2014 iii

Acknowledgements

Bathymetry data shown in some figures was provided by the Port of Hastings Development Authority.

Data for EPA water quality monitoring sites was provided by EPA Victoria.

Aerial imagery is © Google Earth.

Report name: “North Arm Subtidal Seagrass and Water Quality Monitoring. Spatial variation in subtidal seagrass depth limits in Western Port, February 2014.”

Report to: Port of Hastings Development Authority 2/34 High Street Hastings Victoria 3915 AUSTRALIA

Report authors: Scott Chidgey, Peter Crockett and Percival Ho CEE Consultants Pty Ltd PO Box 201 Richmond VIC 3121

[email protected]

www.cee.com.au

North Arm Subtidal Seagrass and Water Quality Monitoring

Spatial variation in subtidal seagrass depth limits

1 INTRODUCTION The Port of Hastings Development Authority (the Authority) is investigating the feasibility of developing a container terminal at the Port of Hastings, Western Port. Development of a container terminal will require assessment of the environmental effects of the proposal on the Western Port ecosystem. The Authority is committed to a detailed period of study to understand the current environmental, social and economic conditions of the Western Port region.

The effects of marine infrastructure construction and ongoing operations on the marine ecosystem and water quality in Western Port will be key considerations of the environmental assessment of the Project. Collecting current information on the ecology of Western Port in and around the port expansion area is a corner-stone of environmental investigations for the container expansion project. A series of summer baseline surveys are the first steps to achieve this.

Seagrasses are major habitat forming plants in Western Port and are fundamental to the structure and function of the ecosystem. The current distribution of intertidal and subtidal seagrasses and their environmental dependencies are recognised as priority areas for investigation by the Authority. The current distribution of subtidal seagrasses will reflect the integration of dependencies on seabed type and light, nutrient and current characteristics. Historic data indicates that there is substantial variation in the lower depth limit of subtidal seagrasses between different parts of Western Port. The causes of this variation have been identified previously as differences in light attenuation (a product of water quality) around Western Port.

CEE Consultants Pty Ltd (CEE) was commissioned by the Authority to investigate the variation in the lower depth limit of subtidal seagrasses around Western Port. The investigations focus on the major habitat forming species Zostera nigricaulis and the relationship between water quality (light attenuation) and its lower depth limit. Investigations will include collection of spatial data on seagrass distributions (using towed video) and morphological measures (using limited collection of Zostera material). CEE collected incidental data on smaller scale variation in seagrass species’ distribution and abundance through long towed video transects.

1.1 This document This document presents the data collected in the January 2014 survey of subtidal seagrass depth limits and how these may relate to the light environment, bathymetry and seabed of Western Port. The information in the report is intended to inform early stages of planning water quality baseline monitoring and to provide a basis for further seagrass mapping, baseline monitoring and experimental studies.

Spatial variation in subtidal seagrass depth limits, January 2014 2

2 SCOPE OF WORK The scope of work for this task was to:  Document the lower depth limit of seagrass in the lower North Arm, and at representative locations elsewhere in upper North Arm, Rhyll Segment and Corinella segment.  Document the amount of light reaching seagrass at its lower depth limit during the survey  Document species identity and morphology at different locations

3 PURPOSE OF TASK The purpose of this task was to:  Provide documentation of the lower boundaries of subtidal seagrass for mapping onto GIS  Provide the basis for calculation of the area of subtidal seagrass in the North Arm using the documented seagrass lower depth limits and available detailed bathymetry, and to provide a basis for the area of subtidal seagrass in other segments of Western Port to be estimated  Provide a basis for positioning seagrass and water quality monitoring sites  Provide baseline documentation of the present depth distribution of seagrass  Provide information on seagrass species distribution and morphology that will inform development of other seagrass related tasks such as light/condition relationships, seasonal variation and interannual variation

Figure 1 Major geographical segments and other features of Western Port (Marsden et al. 1979).

Spatial variation in subtidal seagrass depth limits, January 2014 3

4 METHODS 4.1 Sites investigated The primary of focus of the study was the area in the vicinity of the proposed port development north of Long Island Point. Marine scientists from the Authority and CEE identified priority areas for investigation in Western Port that may represent water quality conditions ranging from high turbidity, to moderate turbidity, to lower turbidity. The areas for primary investigation included Upper North Arm (high turbidity), Lower North Arm (moderate turbidity and area of proposed port development) and the Confluence Zone (Figure 1).

Sites were positioned systematically to comprehensively document subtidal seagrass in the North Arm. Further sites were positioned in the Confluence Zone, Rhyll and Corinella segments. Sites were positioned by dividing the study area into a 2 km by 2 km grid with sites positioned randomly in areas of suitable habitat within each cell of the grid.

A total of 62 sites and 15 transects were investigated throughout Upper and Lower North Arm, and in the Confluence Zone, Rhyll and Corinella segments (Figure 2). Further details of sites are provided in the sections below.

Figure 2 Key Maps

Spatial variation in subtidal seagrass depth limits, January 2014 4

4.2 Subtidal seagrass lower depth limit The lower depth limit (LDL) of subtidal seagrass was determined at 62 sites. The positions of these sites are listed in Table 2 and shown in Map 1 to Map 4. LDL inspections were conducted to provide a detailed picture of large scale variation in the lower depth limit of subtidal seagrass.  40 sites were positioned systematically in Lower and Upper North Arm as shown in Figure 1, in the Confluence Zone, Rhyll Segment and Corinella Segment.  The remaining 22 sites were those where towed video transects were performed (see below)  Areas where LDLs were established historically by CEE (2009) and Bulthuis (1983) were re-visited in this survey. The lower depth limit was calculated based on depth soundings made during the survey, adjusted to Mean Sea Level using sea level records from Stony Point (6 minute intervals, provided by Australian Bureau of Meteorology).

4.3 Transects Fifteen towed video transects were recorded in Western Port at sites shown in Map 5. Transects were conducted to provide a detailed picture of small scale (<1 km) variation in seagrass distributions and abundance.  Transects were aligned perpendicular to depth contours to document the distribution of seagrass along the depth profile  Transects spanned the area between Mean Sea Level (0 m) and the lower depth limit of subtidal seagrass.  A continuous video record, GPS track and depth profile was recorded along each transect. An additional seven transects were recorded while investigating potential sites for instrument deployments (see “North Arm Subtidal Seagrass and Water Quality Monitoring, Preliminary site information”. CEE Consultants, February 2014 (Appendix to this report).

4.4 Light/CTD profiles In-water light (PAR) was measured over depth profiles adjacent to all seagrass sites to document potential spatial variation in light attenuation during the survey.  Light profiles were measured with a 2pi PAR sensor over a minimum water column depth of 10 m to provide sufficient data points for gradient calculation and corresponding light attenuation estimation.  Light intensity (µmol photons m-2 s-1) was measured at 1 m intervals from the seabed to 1 m below the surface to calculate attenuation coefficients for each site.  Measurements in water less than 1 m were avoided due to ‘lensing’ of light by surface ripples that result in highly variable and unreliable light intensity data.  In areas where LDL sites were located close to one another, light profile data from a single adjacent site was used to described light availability at each LDL site.

 Light attenuation in water coefficients (Kd) were calculated as the negative gradient of the log(light intensity)/depth relationship for each site such that:

Iz = I0 exp (-Kd Z) or Kd = -ln(ΔI)/ ΔZ where Kd = attenuation coefficient

Iz = light irradiance at depth of measurement (Z)

I0 = light irradiance at the surface Z = depth of measurement

ΔI = difference in light irradiance over depth increment ΔZ

Spatial variation in subtidal seagrass depth limits, January 2014 5

Map 1 – Upper North Arm

Spatial variation in subtidal seagrass depth limits, January 2014 6

Map 2 Lower North Arm (north)

Spatial variation in subtidal seagrass depth limits, January 2014 7

Map 3 Lower North Arm (south)

Spatial variation in subtidal seagrass depth limits, January 2014 8

Map 4 Confluence Zone, Rhyll and Corinella

Spatial variation in subtidal seagrass depth limits, January 2014 9

Map 5 Location of towed video transects

Spatial variation in subtidal seagrass depth limits, January 2014 10

Map 6 Proposed light monitoring sites

Spatial variation in subtidal seagrass depth limits, January 2014 11

4.5 Seagrass taxonomy Early mapping and studies of seagrass in Western Port (eg NSR 1974, Bulthuis & Woelkerling 1983) documented that the seagrass Zostera nigricaulis (previously known as Heterozostera tasmanica, then Heterozostera nigricaulis) was the most extensive subtidal and intertidal seagrass in Western Port (and see Chidgey et al. 2009 for more information on marine ecosystem characteristics in Western Port). Three other species of seagrass (Zostera muelleri, Halophila australis and Amphibolis antarctica) and the macroalga Caulerpa cactoides also contribute significantly to the marine vegetation habitat below mean sea level in Western Port (see Section 6.4 for discussion of intertidal conditions).

The presence of a woody black stem in Z nigricaulis (Figure 3) generally distinguishes this species from the similar-looking Z muelleri, which lacks the stem. Young plants of Z nigricaulis are externally similar to Z muelleri and can only be distinguished by microscopic examination of rhizome sections. The other seagrass species are readily distinguished by gross morphology.

The Zostera beds at all sites examined by CEE in January 2014 contained predominantly black stemmed seagrasses, which we interpreted as beds of Zostera nigricaulis. Some smaller plants in these beds lacked black stems and may therefore have been Zostera nigricaulis or Z muelleri. Plants were collected from a range of sites in the January 2014 investigation for further examination. Preliminary results of the examinations are presented in Section 5 of this report. The outcomes of further examination will be included in the next study task report “Western Port seagrass characteristics and recommendations for seagrass monitoring”.

Figure 3 Typical subtidal plants in Western Port

Spatial variation in subtidal seagrass depth limits, January 2014 12

4 ZOSTERA LOWER DEPTH LIMIT SITE RESULTS The tables and figures that follow illustrate the variation in lower depth limits and water quality parameters at the Z. nigricaulis seagrass sites surveyed in Western Port in January 2014.

Table 1 (page 12) shows a summary of Z. nigricaulis seagrass lower depth limits measured in January 2014.

Figure 4 (page 13) shows the relationship between Secchi depth and light attenuation at seagrass LDL sites in January 2014.

Figure 5 (page 18) shows the positions of the sites and the lower depth limits of Z. nigricaulis at each site.

Figure 6 (page 19) shows the light attenuation coefficient for each site measured on the day of the site visit, and also includes the average light attenuation coefficients at EPA monitoring sites calculated by CEE from EPA monthly monitoring data from 2007 to 2010. CEE recently obtained all EPA data for the Western Port monitoring sites to 2014. A full analysis of the light data will be presented in a separate report.

Table 2 (page 15 and following) provides metadata for all sites on the day they were examined including: site positions; lower depth limit Z. nigricaulis seagrass; light attenuation co-efficient; percent surface light at LDL; Secchi disk depth; mean turbidity, and; the gradient of the seabed immediately below the seagrass depth limit. The data for sites are grouped based on which segment of Western Port they occupy.

Table 1 Summary of Zostera nigricaulis lower depth limit data Depth limits (metres below MSL) Median light attenuation Segment Sites -1 Max Min Median Jan 2014 (Kd, m ) Upper North Arm 11 -4.7 -1.7 -2.8 0.35 Lower North Arm 36 -7.5 -1.3 -4.7 0.36 Confluence Zone 4 -4.0 -1.6 -2.3 0.27 Rhyll 3 -2.9 -1.0 -1.3 0.37 Corinella 5 -2.9 -1.0 -1.3 0.34

Table 1 and Figure 5 shows that there is substantial variation in Z. nigricaulis seagrass lower depth limits around Western Port, and a wide range between maximum and minimum depth limits within each segment.

The deepest maximum depth limit was found in Lower North Arm, followed by Upper North Arm, the Confluence Zone, Corinella and Rhyll segments. Median depth limits were highest in Lower North Arm and lowest in the Rhyll and Corinella segments. At many sites Z. nigricaulis did not reach into the subtidal (their lower depth limit was less than 1.6 metres below MSL):

Spatial variation in subtidal seagrass depth limits, January 2014 13

4.6 Light attenuation Table 1, Table 2, Figure 4 and Figure 6 show the variation in light attenuation coefficients varied between segments of Western Port at the time of the survey (January 2014). Light attenuation was lowest (the water was clearest) in the Confluence Zone and highest in ebbing waters in the Corinella Segment.

8 7 6 5 4 3

Secchi disk depth, m 2 1 0 0 0.2 0.4 0.6 0.8 1 Light attenuation coefficient, Kd

Figure 4. Plot of Secchi disk depth versus light attenuation coefficient Measured at 48 sites in Western Port, January 2014

Light attenuation coefficients measured during January 2014 were below the long term EPA averages (EPA Victoria data 2007 - 2010) of 0.6 m-1 in Upper North Arm, 0.38 m-1 in Lower North Arm and 1.42 m-1 in the Corinella segment. The long term EPA data show considerably greater difference in water clarity between the upper North Arm near Crawfish -1 - Rock and the Lower North Arm at Hastings (Kds 0.60 m and 0.38 m 1, respectively) than -1 -1 was measured in January 2014 (Kds ranging from 0.33 m to 0.4 m in both areas).

These comparisons indicate that the Bay waters were clearer than average during the January 2014 survey period, which was characterized by calm conditions and a long period without rain preceding the investigations.

Spatial variation in subtidal seagrass depth limits, January 2014 14

4.7 Maximum depth limits The maximum depth limits for Z. nigricaulis were generally found on the west side of Lower North Arm, including the area immediately north of the Port of Hastings. These limits corresponded with a light availability of approximately 5-10 per cent of surface light. It can be inferred that light availability Z. nigricaulis at these sites is close to that which is limiting for Z. nigricaulis in Western Port.

4.8 Seabed slope At many sites seabed conditions appeared to be important in determining the distribution of subtidal seagrasses. Sites where Z. nigricaulis reached its greatest depths were those with gently sloping seabed (< 4 % gradient). At many sites with relatively shallow Z. nigricaulis limits, the gradient of the seabed below the seagrass was over 10% and the lower boundary of the continuous dense Zostera seagrass bed was marked by a clear, undercut edge. These characteristics are shown in the transects plotted in Section 5 of this report.

Other factors not documented in these investigations are also likely to be influential to the distribution of subtidal Z. nigricaulis in Western Port.

Western Port Subtidal Seagrass Distribution Study - 2014 15

Table 2. Zostera LDL site metadata, Western Port January 2014

Position Light SI at Secchi Parameters Zostera Lower Seabed Gradient Turbidity Site (WGS 84/MGA, 55H) Kd from Attenuation LDL Depth measured Depth Limit (m) Below Seagrass (%) (NTU) Easting Northing (m-1) (%) (m) UPPER NORTH ARM UNA-1 356263 5761427 LDL & Kd -4.5c No map 0.40 23 4.6 0

UNA-2 355988 5764811 LDL UNA-3 -4.7b 0.7 0.35 21 5.2 0 UNA-3 355942 5765017 LDL & Kd -1.9c No map 0.35 59 5.2 0

UNA-4 354619 5763121 LDL & Kd -1.7c No map 0.33 70 5.1 0

UNA-5 354152 5761745 LDL & Kd -3.6c No map 0.36 38 4.6 0

UNA-6 352556 5763772 LDL & Kd -3.3b 1.1 0.37 30 4.9 0

UNA-7 352464 5762508 LDL & Kd -2.3c 12.5 0.35 66 5.2 0

Charing Cross T1 355988 5764811 Video transect UNA-3 -2.8a 3.8 0.35 19 5.2 0 Charing Cross T2 356206 5764895 Video transect UNA-3 -1.8a 3.8 0.35 74 5.2 0 Joe's Island T1 356207 5761430 Light profile UNA-1 -2.8a 7.9 0.40 46 4.6 0 Joe's Island T2 356142 5761561 Light profile UNA-1 -4.1 7.9 0.40 27 4.6 0 LOWER NORTH ARM

LNA-1 349139 5764175 LDL & Kd -6.1b 1.1 0.38 9 4.9 0

LNA-2 347185 5763474 LDL & Kd -5.5a 1.0 0.36 12 4.9 0

LNA-3 346453 5762683 LDL & Kd -6.9a 1.1 0.42 5 4.9 0

LNA-4 350146 5761953 LDL LNA-5 -6.1c 3.5 0.36 17 - 0 LNA-5 349601 5761888 LDL & Kd -3.9c 6.2 0.36 38 - 0

LNA-6 349217 5761887 LDL & Kd -3.7c 4.3 0.37 41 5.2 0

LNA-7 345582 5761489 LDL & Kd -6.4a 1.5 0.40 6 4.9 0

LNA-8 349456 5760947 LDL LNA-9 -2.9c 3.5 0.38 54 5.4 0 LNA-9 349988 5760592 LDL & Kd -5.1c 3.8 0.38 25 5.4 0

LNA-10 349578 5757983 LDL & Kd -5.3c 6.0 0.33 28 - 0

LNA-11 345018 5757730 LDL & Kd -5.8b 6.0 0.34 22 4.9 0

LNA-12 344506 5755636 LDL & Kd -6.1b 3.3 0.39 16 4.2 0

LNA-13 348150 5755595 LDL & Kd -7.5c 6.7 0.30 16 - 0

LNA-14 344493 5754770 LDL & Kd -4.6b 3.8 0.36 32 4.5 0

Note: Superscripts “a”, “b” and “c” denote confidence in accuracy of Zostera lower depth limits. a = good, b= reasonable, c = fair. SI denotes surface irradiance.

Western Port Subtidal Seagrass Distribution Study - 2014 16

Table 2 Cont’d Position Zostera Lower Seabed Gradient Light SI at Secchi (WGS 84/MGA, 55H) Parameters Turbidity Site Kd from Depth Limit Below Seagrass Attenuation LDL Depth measured (NTU) Easting Northing (m) (%) (m-1) (%) (m)

LOWER NORTH ARM cont’d LNA-15 347934 5754781 LDL LNA-16 -2.9c 5.5 0.33 57 - 0 LNA-16 348778 5754759 LDL & Kd -3.2c 4.2 0.33 52 - 0

LNA-17 344713 5752245 LDL & Kd -6.8b 4.1 0.28 21 5.1 0 LNA-18 347535 5751869 LDL & Kd -1.7c 3.8 0.28 76 5.7 0 LNA-19 347754 5751899 LDL LNA-18 -3.3c 2.0 0.28 57 5.7 0 LNA-20 348689 5751892 LDL & Kd -3.4c 2.6 0.28 57 5.1 0 LNA-21 345559 5750118 LDL & Kd -6.5b 3.7 0.28 22 4.5 0 LNA-22 348655 5749863 LDL & Kd -6.1b 2.9 0.36 18 5.2 0 Quail Island 350205 5764164 Video transect LNA-1 -3.8a 5.6 0.38 20 4.9 0 Quail Island 350167 5764051 Light profile LNA-1 -4.1b 8.9 0.38 15 4.9 0 Yaringa 347436 5763296 Light profile LNA-3 -4.7a 2.0 0.42 7 4.9 0 The Bluff 346425 5762644 Video transect LNA-3 -4.7 1.4 0.42 8 4.9 0 North BlueScope 345522 5761263 Video transect LNA-7 -5.0a 2.7 0.40 5 4.9 0 Long Island Point 345045 5757981 Video transect LNA-7 -1.4a 18.3 0.35 39 5.2 0 MiddleSouth Spit 346605 5756173 Light profile 656 -4.7a 14.7 0.52 10 2.5 0 Middle Spit North 348377 5760930 Video transect LNA-6 -3.2a 10.7 0.37 18 5.2 0 Middle Spit South 347042 5754845 Video transect -2.7a 10.7 NA NA NA NA North Arm channel 346704 5755393 Video transect 656 -5.6a 10.2 0.38 54 4.5 0 mark No.1 Chilcott Channel 349298 5755556 Video transect -1.3a 8.1 NA NA NA NA Stony Point North 344714 5752291 Video transect LNA-21 -3.5a 9.6 0.28 68 5.1 0 Stony Point 344704 5752545 Light profile LNA-17 -7.4a 3.7 0.28 14 5.1 0 Tea Tree Point 348592 5749476 Light profile LNA-22 -4.5b 13.1 0.36 20 5.2 0 Note: Superscripts “a”, “b” and “c” denote confidence in accuracy of Zostera lower depth limits. a = good, b= reasonable, c = fair. SI denotes surface irradiance.

Western Port Subtidal Seagrass Distribution Study - 2014 17

Table 2 Cont’d

Positions Seabed Gradient Light Secchi (WGS 84/MGA, 55H) Parameters Zostera Lower SI at LDL Turbidity Site Kd from Below Seagrass Attenuation Depth measured Depth Limit (m) -1 (%) (NTU) Easting Northing (%) (m ) (m)

CONFLUENCE ZONE CZ-1 348406 5748042 LDL & Kd -1.8c 2.1 0.29 59 6.1 0 CZ-2 345990 5747954 LDL & Kd -1.6b 4.5 0.23 87 5.5 0 CZ-3 349436 5746747 LDL & Kd -2.1c 1.6 0.27 54 5.8 0 CZ-4 345445 5746585 LDL & Kd No seagrass No seagrass 0.21 No seagrass 7.4 0 Tortoise Head South 348671 5746526 Video transect CZ-3 -4.0a 1.3 0.27 33 5.8 0 T1 Tortoise Head South 349115 5746364 Video transect CZ-3 No Zostera 0.5 0.27 NA 5.8 0 T2 Tortoise Head South 349734 5746299 Video transect CZ-3 No Zostera 0.3 0.27 NA 5.8 0 T3 RHYLL SEGMENT RS-1 351097 5745583 LDL & Kd -1.3c 3.1 0.29 69 6.9 0 RS-2 352707 5745537 LDL RS-3 -1.0c 2.6 0.37 55 - 0 RS-3 352869 5745480 LDL & Kd -2.9c 2.8 0.37 28 - 0 CORINELLA SEGMENT CS-1 361980 5748751 LDL & Kd -3.2b No map 0.34 30 - 0 CS-2 362163 5747990 LDL CS-1 -3.0b No map 0.34 32 - 0 CS-3 362159 5747893 LDL CS-1 -2.8b No map 0.34 35 - 0 CS-4 362196 5750360 LDL & Kd No seagrass No seagrass 0.77 No seagrass 1.9 1.38 Corinella 361976 5748756 Video transect CS-1 -3.0a 1.1 0.34 34 - 0 Note: Superscripts “a”, “b” and “c” denote confidence in accuracy of Zostera lower depth limits. a = good, b= reasonable, c = fair. SI denotes surface irradiance.

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Figure 5 Depth limits for Zostera nigricaulis at sites around Western Port – January 2014

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Figure 6 Light attenuation coefficients calculated during this investigation and EPA fixed sites This study (white) EPA sites (yellow, 2007-2010)

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5 TRANSECT DESCRIPTIONS Summaries of the bathymetric and vegetation characteristics of the 15 towed video transect sites are provided below.

4.9 Charing Cross Charing Cross is located in Upper North Arm and was the site of numerous seagrass studies through the 1970s and 1980s by Bulthuis & Woelkerling 1983. Water quality in this area is generally poor – the site is located downstream of ebb tides draining the highly turbid areas towards the embayment head - an area where large amounts of intertidal seagrass were lost in the 1980s. The 2014 investigations found patchy intertidal and a narrow band of subtidal Z. nigricaulis along the two transects at Charing Cross (Figure 7, Figure 8 and Figure 9). The deepest extent of Z. nigricaulis on either transect was around 5.5 m, though dense ‘beds’ were limited to water less than 3 m deep. Aerial imagery for the area suggests there is extensive intertidal Zostera on some of the mudflats around Charing Cross (Figure 7). The sides of the tidal channels in the area are steep, a factor that may influence the distribution of subtidal Z. nigricaulis in the area.

Figure 7 Bathymetry and aerial image (Feb 2013) of Charing Cross transects

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Figure 8 Charing Cross Transect 1 vegetation profile

Figure 9 Charing Cross Transect 2 vegetation profile

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4.10 Quail Island Quail Island is located to the east of Watsons Inlet and Yaringa. Bathymetric contours are oriented east-west in this part of Western Port (Figure 10) and saltmarsh, mangroves and seagrass occur in the intertidal. The transect spanned depths from 7 m to 1 m. This transect found dense subtidal Z. nigricaulis beds occupy the gently sloping seabed to around 4 m depth (Figure 11). Z. nigricaulis was absent beyond around 4 m and the slope of the seabed became substantially steeper past this depth.

Figure 10 Bathymetry and aerial image of Quail Island transect

Figure 11 Quail Island transect vegetation profile

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4.11 The Bluff ‘The Bluff’ transect was located to the south of Watsons Inlet. Bathymetric contours are oriented southwest to northeast here with saltmarsh, mangroves and seagrass in the intertidal (Figure 12). The transect spanned depths from 8 m to 1 m. This transect found dense subtidal Z. nigricaulis to around 6 m depth on seabed with an even, gentle gradient both above and below the subtidal seagrass beds (Figure 13).

Figure 12 Bathymetry and aerial image of The Bluff transect

Figure 13 The Bluff transect vegetation profile

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4.12 North BlueScope The North BlueScope transect was located to the north of the BlueScope Steelworks wharf. Bathymetric contours are oriented approximately north-south with saltmarsh, mangroves and seagrass in the intertidal (Figure 14). An intertidal lagoon that retains water at low tide occupies around one third of the intertidal mud-flats and is clearly visible in aerial images. The transect spanned depths from 8.5 to 1.2 m. The transect found extensive intertidal and subtidal Z. nigricaulis beds with the deepest extent of subtidal Z. nigricaulis being around 6.5 m. The seabed sloped very gently from 1 to 2 m depth and had a steeper, but steady gradient from 2 to 9 m depth.

Figure 14 Bathymetry and aerial image of North BlueScope transect

Figure 15 North BlueScope transect vegetation profile

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4.13 Long Island Point South The Long Island Point South transect was located south of the Long Island Point (Esso) jetty. Bathymetric contours here are oriented north-south and the seabed is modified by the dredged harbour basin (Figure 16). Nearshore the seabed slopes gently between 1.2 and 2.5 m. This gently sloping seabed ends abruptly at the edge of the dredged harbour basin and then slopes steeply from 2.5 to 9 m depth. The transect spanned depths between 9 and 1.2 m. Dense Z. nigricaulis was found between 1. and 1.5 m depth, with mixed Z. nigricaulis, Caulerpa and Halophila found to around 2 m. No Z. nigricaulis was found in the modified (dredged) area of the transect (Figure 17).

Figure 16 Bathymetry and aerial image of Long Island Point South transect

Figure 17 Long Island Point South transect vegetation profile

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4.14 Middle Spit 4.14.1 Middle Spit North The Middle Spit North transect (Figure 18) covered the steeply sloping western bank of northern Middle Spit, spanning depths from 8.5 to 1.5 m (Figure 19). The seabed rises from 8.5 m to a ridge at 2.5 m depth over around 50 m. East of this feature there is a narrow 4.5 m deep channel before the seabed rises steeply to 3 m after which it slopes gently to around 1 m depth. Zostera nigricaulis was seen to just over 4.5 m depth but dense beds were limited to depths between 3.3 and 2.5 m, and seagrass was patchy in water shallower than 2.5 m (Figure 18, Figure 19).

Figure 18 Bathymetry and aerial image of Middle Spit North transect

Figure 19 Middle Spit North transect vegetation profile

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4.14.2 Middle Spit South The Middle Spit South transect covered the steeply sloping western bank of southern Middle Spit (Figure 20). The seabed here rises steeply from a depth of 10 m to less than 3 m over a distance of less than 20 m. From around 3 m depth the seabed slopes gently across the top of middle spit. The transect spanned depths from 12 to 1.5 m (Figure 21). Subtidal Z. nigricaulis occurred patchily in water less than 3 m deep (Figure 20, Figure 21).

Figure 20 Bathymetry and aerial image of Middle Spit South transect

Figure 21 Middle Spit South transect vegetation profile

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4.14.3 North Arm channel mark No. 1 Channel mark no. 1 in North Arm is at the southern end of a shoal/subtidal sandbar to the east of Middle Spit. The shoal slopes steeply on its western side, rising from 9 to 1.5 m over less than 60 m distance (Figure 23). The top of the shoal has a gentle slope to the east between 1.5 and 2.5 m and a steeper slope between 2.5 and 5.5 m. The transect spanned depths from 9 to 1.5 m. Mixed Zostera/Caulerpa/Halophila occurs on the top of the shoal with dense Z. nigricaulis on its eastern side between 2 and 6 m depth.

Figure 22 Bathymetry and aerial image of North Arm Channel Mark No. 1 transect

Figure 23 North Arm Channel Mark no. 1 transect vegetation profile

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4.15 Chilcott Channel Chilcott Channel is a shallow, narrow channel running north-south between French Island and Middle Spit Channel (Figure 24). The steep sided channel is bounded on both sides by intertidal sand/mudflats. Dense Zostera beds could be seen in intertidal areas to both the east and west of the channel. The transect spanned depths from 0 to 4 m depth. The area did not appear to support subtidal Z. nigricaulis beds, the deepest extent of dense Zostera being around 1.3 m.

Figure 24 Bathymetry and aerial image of Chilcott Channel transect

Figure 25 Chilcott Channel transect vegetation profile

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4.16 Stony Point North The Stony Point North transect was just to the north of the navigation channel into the Stony Point Jetty. Bathymetric contours here are oriented north-south with a wide area of intertidal mudflats, including a tidal lagoon with seagrass, backed by mangroves. The transect spanned depths from mean sea level to around 7 m depth. Between 0 and 2 m depth the seabed slopes gently from west to east. Past 2 m the slope of the seabed is steeper, going from 2 to 7 m depth over around 40 m. Dense Z. nigricaulis was found to around 1.5 m below which a mix of Halophila australis and Caulerpa was present. Dense Z. nigricaulis appears to be confined to intertidal depths in this area.

Figure 26 Bathymetry and aerial image of Stony Point North transect

Figure 27 Stony Point North transect vegetation profile

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4.17 Tortoise Head South Three transects were recorded on the sand spit to the south of Tortoise Head. This area is just outside the boundary of North Arm and receives limited ocean swell energy. The sand spit slopes gently to the west and is steeper on its north and south boundaries (Figure 28) The three transects spanned depths from 8 to 2.5 m.

Figure 28 Bathymetry and aerial image of Tortoise Head South transects

Transect 1 spanned depths from 8 to 4 m depth (Figure 29). Seabed below 5 m was bare of vegetation but above this dense Halophila australis seagrass was seen. A small patch of sparse Z. nigricaulis was seen at the deeper edge of the Halophila bed.

Figure 29 Tortoise Head South transect 1 vegetation profile

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Transect 2 spanned depths from 3.6 to 3 m and was also dominated by dense Halophila australis (Figure 30).

Figure 30 Tortoise Head South transect 2 vegetation profile

Transect 3 spanned depths from 3 to 2.5 m and was dominated in its entirety by dense Amphibolis antarctica seagrass (Figure 31).

Figure 31 Tortoise Head South transect 3 vegetation profile

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4.18 Corinella Corinella is located to the east of French Island. The Corinella transect traversed the sand/mud bank and channel to the north of the Settlement Point jetty and boat ramp (Figure 32). The transect spanned depths between 7and 0.5 m depth. Dense Z. nigricaulis was seen to around 3 m depth on the northern side of the sand/mud bank and across its top between 1 and 1.5 m depth. A ridge of sand on the southern side of the mud bank (visible in the aerial image) was bare of vegetation, though dense Z. nigricaulis occurred on its southern side.

Figure 32 Bathymetry and aerial image of Corinella transect

Figure 33 Corinella transect vegetation profile

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5 ZOSTERA NIGRICAULIS SAMPLE MORPHOMETRICS Five samples of Zostera seagrasses were examined from both subtidal and intertidal depths near Stony Point, Middle Spit and Chilcott Channel (Table 3).

The samples were collected by scooping under the seagrass rhizomes and retrieving a complete sod of sediment, seagrass roots and rhizomes, shoots and leaves for initial processing on the survey vessel and subsequent examination in the laboratory.

Each sod was initially rinsed to remove sediment (clays and silts) and other non-seagrass material (many empty bivalve shells and living invertebrates) from the dense tangle of seagrass roots, rhizomes and stems. It is likely that the tangled basal material represents years of accumulated dead seagrass roots, rhizomes and stems. The samples were labelled and frozen for subsequent examination.

During the laboratory sorting process, it was found to be very difficult to extract intact continuous sections of rhizome with stems attached from the tangled, basal mass. This was due to the tightly interwoven and tangled seagrass rhizomes, large amount of detritus and brittle nature of Z. nigricaulis rhizomes and stems. Only a small number of relatively short sections of rhizome could be retrieved intact for measurement from each sample. As a result, measurement of shoot density per rhizome length was limited and rhizome morphometric data is less informative than the stem and leaf morphometrics.

Measurement of stem and leaf morphometrics were more practical to attain with generally higher sample sizes (specimens from each sample measured) and hence greater confidence in the data. Table 3 Preliminary seagrass morphology data Data are: average (n) Stony Point Middle Spit Chilcott Channel Parameters Sub Sub Inter Sub Inter measurements in mm tidal tidal tidal tidal tidal Rhizome Length over all 10 (8) 26.7 (3) 65.5 (8) 172 (6) 101 (4) morphology Nodes 2 (8) 5.3 (3) 5.5 (8) 7.5 (6) 8.5 (4) Branches 0 (8) 2.3 (3) 0 (7) 2 (5) 3 (4) Direct Shoots 2 (8) 2 (3) 6 (8) 1.8 (6) 2 (4) Indirect shoots (7) 0.5 (2) 0 (7) 2 (5) 2.3 (4) mm between nodes 5 5 12 23 12 mm between shoots 5 13 11 96 51 mm between branches 12 86 34

Median thickness 1.5 (3) 1.9 (6) 1.4 (5)

Stem and Length over all 355 (9) 219 (10) 220 (8) 282 (12) 223 (11) leaf Nigricaulis length 173 (9) 111 (9) 166 (8) 108 (10) 135 (11) morphology Nigricaulis nodes 8.5 (9) 12.2 (9) 8.5 (8) 5.9 (10) 9.9 (11) mm between nodes 20 9.1 20 18 14 Branches 0 (4) 0 (9) 0.8 (7) 0 (10) 0 (11) Leaf clusters 1 (9) 1 (9) 4.6 (5) 1 (11) 1.5 (11) Leaves 6.3 (9) 5.3 (9) 8.8 (8) 4.3 (12) 6.6 (11) Leaf length 114 (9) 87 (10) 47 (8) 124 (18) 88 (15) Bract length 55 (9) 26 (10) 21 (8) 52 (18) 27 (15) Leaf Width 1.6 (7) 1.2 (13) 1.18 (5) 1.64 (6) 1.5 (12) morphology Thickness 0.13 (7) 0.11 (13) 0.06 (5) 0.1 (6) 0.12 (12)

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Overall, there were substantial differences in morphometrics between samples, in particular stem (nigricaulis) length, leaf length, number of leaf clusters and leaf thickness. These latter parameters will be measured in the remaining samples to assess for potential differences between site, depth and location for the next phase of seagrass monitoring.

Issues encountered during work on this task suggest that future sampling should collect only above seabed material: stems and associated leaf material. This is also less destructive to the seagrass beds. Shoot density can be assessed by collecting material from standard 0.25 x 0.25 m quadrats.

Processing of remaining samples will focus on the more practical stem and leaf morphometrics and on identification of species through microscopic examination of vascular structure. These will be reported in the next phase of the preliminary seagrass studies

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6 SUMMARY DATA INTERPRETATION AND OBSERVATIONS The investigations of seagrass lower depth limit distribution and associated environmental measures in Western Port in January 2014 have revealed important facts relevant to the Project and further environmental investigations. The findings are consistent with previous investigations of seagrasses in Western Port.

6.1 Lower depth limit of Zostera and determining factors The lower depth limit of Zostera varied substantially between sites throughout the Lower North Arm, and between sites at the other locations.

The collected data and the observations of the study team during the investigations show that the lower limit of Zostera seagrass often coincided with a rapid change in the seabed profile or slope at the edge of a channel. This was the case at most of the sites inspected during the January 2014 investigation. The lower edge of the seagrass bed in these circumstances was often undercut. In general, the shallower lower depth limits of seagrass (less than 4 m below MSL) coincided with relatively steep banks, where the seabed sloped steeply from the intertidal flats into adjacent channels.

In contrast, the sites with deeper lower depth limits of Zostera were characterized by seabed that sloped gently and constantly from the lower intertidal to depths greater than the lower depth limit of Zostera seagrass. The deepest lower depth limits (6 m to 7 m) were recorded at sites on the west side of Lower North Arm. It is likely that light is the factor limiting the lower depth limit of Zostera seagrass at these sites.

The lower depth limit of Zostera including northern Western Port is dependent on a range of factors including:  Amount of available light;  Water quality;  Seabed slope;  Water currents;  Slope aspect;  Seabed composition; and  Turbulence. Many of these factors are not independent and also may affect the presence or absent of seagrass at a particular site. Seagrass is absent from large areas of seabed that appear to have a suitable light climate.

Of particular relevance to the project is the implication that light is not the determining factor in the lower depth limit of seagrasses in many locations in Lower North Arm and possibly Upper North Arm. Seagrasses in areas of similar light climate in Lower North Arm may grow to depths of 7 m below MSL on the west side of the main channel where the seabed slope is gentle, but grow to only 2.4 m on the eastern side of the channel at Middle Spit where the seabed slopes steeply. At this stage, it appears that light is the major determining factor in the lower depth limit of seagrasses in Lower North Arm only on the western bank from Stony Point to approximately Yaringa. Other factors, notably seabed slope and therefore water currents appear to be more important than light in determining the lower depth limit and possibly presence or absence of seagrass at most other sites.

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It is not known at this stage if there is seasonal or interannual variation in the lower depth limit of the seagrasses at depths limited by light.

6.2 Most extensive subtidal seagrass The extent of subtidal seagrasses in Western Port has not been previously systematically determined. The January 2014 investigations indicate that most extensive continuous subtidal seagrass meadows in northern Western Port appear to extend approximately 8 km along the northwestern side of the Lower and Upper North Arm from BlueScope to Quail Island.

These meadows include a mixture of dense Zostera seagrass (mostly Z. nigricaulis) and areas of patchy or less dense seagrass. Patches and bands of the seagrass Halophila australis and alga Caulerpa cactoides were common, particularly at the upper and lower boundaries of the Zostera meadow. The Zostera seagrass meadows in this area extend from approximately 1.0 m below MSL (intertidal) to a maximum depth of almost 7 m below MSL just north of BlueScope.

The slope of the seabed below the intertidal mudflats in this area between BlueScope and Quail Island is relatively gentle and the area of seagrass consequently extends over a band between 500 m and almost 1 km wide.

6.3 Light requirement of Zostera seagrass The lower depth limit of Zostera at sites where light appears to limit the vertical extent of Zostera is approximately 6.5-7 m. The sites are located between two EPA monitoring sites where the 2008 to 2010 average light attenuation coefficients in that area of Western Port are 0.38 m-1 (Hastings) and 0.60 m-1 (Barralier Island). Figure 34 shows the range of light attenuation conditions that could be expected from the long term 20 percentile, 50 percentile and 80 percentile Kds from the combined Hastings and Barralier Island data.

Hastings and Barralier EPA data Percentage of surface light 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 0

1

2

3 Attenuation coefficient, k

4 20% ile 50% ile 5 80% ile

Depth, m 6

7 Light may be limiting 8

9

10

Figure 34. Possible annual light range in north of Lower North Arm Western Port

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The figure indicates that Zostera at approximately 7 m depth in the north of receives approximately 5 percent of the annual surface light. This is the same annual minimum requirement of “~ 5 % of surface irradiance in order to become established and/or survive” calculated for this species in Western Port and Port Phillip Bay using similar methods but different source data in 1979 (Bulthuis 1983).

The amount of light (for example µmol per day) received by seagrasses at a location varies between depth, season (daylength and solar elevation), tide height and obviously night and day. The amount of light received by seagrasses is also dependent on the suspended solids concentration and colour of the water column. These factors may vary with tide, wind, rainfall and other seasonal factors.

The use of light by seagrass may vary from season to season. Seagrass may require more light or less light at different times of the year. There is strong field experimental evidence that seagrasses in Western Port require more light in spring than in winter (Bulthuis 1983).

6.4 Intertidal seagrass Subtidal seagrass extent was the focus of this investigation (depths > 1.8 m below mean sea level). However, some of our transects extended to the intertidal area and included intertidal seagrass distribution (Section 5). It is appropriate to mention key aspects of intertidal seagrass distribution, history and taxonomy briefly here. More detailed discussion and references can be found in Walker 2011, Warry & Hindell 2009 and Chidgey et al. 2009.

Seagrasses in Western Port have been the focus of many studies in the past, including spatial mapping ( NSR 1974, Bulthuis 1981a, Bulthuis 1981b, Bulthuis 1984, Stephens 1995, Ball & Blake 2001, Ball et al. 2010) and biomass and production studies (NSR 1974, Bulthuis 1983, Bulthuis 1981a, Bulthuis & Woelkerling 1983, Campbell & Miller 2002, Walker 2003). Most of these studies were limited to intertidal areas (0 to -1.8 m below MSL) or shallow subtidal areas (see Chidgey et al. 2009). There have been few investigations of subtidal seagrasses (but see MSE 2009, Hall & Chidgey 2013).

Seagrass was mapped from colour aerial photographs and ground truth surveys in 1974 for the Western Port Bay Study (NSR 1974). The study showed extensive areas of intertidal seagrass throughout Western Port. In some parts the macroalga Caulerpa cactoides was also common. The lower boundary of the mapping appeared to be the low tide mark.

Re-mapping of aerial photographs from the early 1970s (Bulthuis 1981b) and mapping in the 1980s and 1990s showed that vast areas of seagrass were lost from the intertidal mudflats from the mid 1970s to the early 1980s (Ball & Blake 2001, Bulthuis 1981a), but the cause of the loss was unclear in spite of on-site investigations at the time (Bulthuis 1984). It was noted that “most of the seagrass has been lost from the intertidal areas while most of the subtidal beds are surviving.” (Bulthuis 1984). The reason for the loss of seagrass remains unclear because evidence from the time (Bulthuis 1981b, Bulthuis 1984, ) shows that the progression of loss was not consistent with smothering, light attenuation due to suspended solids or phytoplankton in the water column, or nutrient enriched growth of epiphytes on the leaves.

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Figure 35. Infra red photograph of tidal divide, north of ay 1977/78 From Harris et al. 1979 Photograph from Erosion Control Project series November 1977 and February 1978, see Bulthuis 1981b

The dominant intertidal seagrass species in northern Western Port prior to the losses in the late 1970s was Zostera nigricaulis as it is now known (Bulthuis 1981b). It is also clear that seagrasses have re-established on the mudflats in many areas since the late 1980s (Stephens 1995, Ball & Blake 2001). Initial studies indicated that Z muelleri was the species recolonising the bare intertidal mudflats (Stephens 1995).

Subsquent large scale mapping using 1999 aerial photographs and extensive ground- truthing (Ball & Blake 2001) did not distinguish a particular Zostera species due the recognised difficulties in distinguishing species in the field. Community seagrass restoration attempts in Western Port selected Zostera muelleri “due to the increased potential of this species to colonise denuded mudflats” (Walker 2003).

The presence of black, lignified stalks in seagrass beds in some intertidal areas during our observations of seagrass in Western Port during January 2014 indicated that at least some of the seagrasses on the intertidal mudflats in Lower North Arm was Zostera nigricaulis. As discussed in Section 4.5, young Z nigricaulis may lack the black stem and look externally identical to Zostera muelleri. It is possible that the seagrasses on the recolonised mudflats are a mixture of Z nigricaulis and Z muelleri.

The extent of intertidal seagrasses in Western Port has not been mapped since 2001 based on aerial photographs taken in 1999 (Blake & Ball 2001), although local seagrass mapping in some intertidal areas was completed in 2007 for comparison with the 1999 areas (Ball et al. 2010). The limitations of intertidal habitat mapping using aerial photography in Western Port has been recognized (Stephens 1995, Blake & Ball 2001) and comprehensive ground- truthing in surveys are incorporated into mapping exercises. Multi-spectral remote sensing or

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sonar (side scan or multibeam) methods have not been applied to previous intertidal mapping in Western Port.

It is 15 years since the intertidal seagrasses of Western Port have been comprehensively mapped and thirty years since the taxonomic composition of the intertidal seagrasses has been examined.

7 CONCLUSION The January 2014 investigation of Zostera seagrass established that the lower depth limit in northern Western Port is dependent on two key factors:  Available light; and  Seabed slope or factors determining seabed slope

Zostera nigricaulis meadows were found to a maximum depth of around 7 m below mean sea level on gently sloping seabed in the Lower North Arm of Western Port. Ambient annual light irradiance at this point was calculated to be approximately 5 percent of surface irradiance. This was consistent with annual light requirement determined in Western Port in the early 1980s. The shorter term and seasonal light requirements of seagrass in Western Port are not known.

Z nigricaulis meadows generally did not extend to their light limited depth in the Lower North Arm. The lower edge of the meadows at many locations ended abruptly at a point where the seabed slope increased significantly. This occurred mostly in depths less than 4 m below mean sea level. Hence it appears that much of the Zostera meadows in Lower North Arm are distributed in depths substantially shallower than their lower light limit.

The most extensive, continuous intertidal/subtidal meadow of Zostera nigricaulis in North Arm appears to extend approximately along 8 km of the northwestern side of the North Arm from BlueScope to Quail Island, over a band between 500 m and almost 1 km wide and to depths of 5 m to 7 m below mean sea level. Hence this continuous Zostera seagrass habitat appears to occupy an area of approximately 5 km2to 6 km2.

The understanding of these factors and the sites where they occur will substantially contribute to: GIS based mapping of the lower depth limit of Zostera in the North of Western Port; designing seagrass monitoring and project targeted experimental investigations, and; assessing the implications of the proposed port development options on the marine ecosystem of North Arm in Western Port.

Western Port Subtidal Seagrass Distribution Study - 2014 41

8 REFERENCES Ball, D. & S. Blake (2001) Seagrass Mapping of Western Port. Victorian Marine Habitat Database. Geospatial Systems Section, Marine and Freshwater Resources Institute, Queescliff. Ball, D., G. D. Parry, S. Heislers, S. Blake, G. F. Werner, P. Young & A. Coots (2010) Victorian multi-regional seagrass health assessment 2004– 07. Fisheries Victoria Technical Report No.66, 105 pages, Department of Primary Industries Victora. (2001) Seagrass Mapping of Western Port. Report, Report authors: Blake, S. & D. Ball. Marine and Freshwater Resources Institute, Queenscliff. Bulthuis, D. (1983) Effects of in situ light reduction on density and growth of the seagrass Heterozostera tasmanica (Martens ex ASchers.) den Hartog in Western Port, Victoria, Australia. Journal of Experimental Marine Biology and Ecology, 67(91-103). Bulthuis, D. A. (1981a) Distribution and Summer Standing Crop of Seagrasses and Macro- Algae in Western Port, Victoria. Proceedings of the Royal Society of Victoria 92, 102- 112. Bulthuis, D. A. (1981b) Some observations on the loss of seagrass in the Upper North Arm, Western Port Victoria. Report of the Marine Science Laboratories, Queenscliff. January 1981. Ministry fro Conservation. Environmental Studies Program. Bulthuis, D. A. (1984) Loss of Seagrass in Western Port, a Proposal for Further Research, 1984/85. Marine Science Laboratories. Internal Report Series, No. 72. Ministry for Conservation. Victoria. Bulthuis, D. A. & W. J. Woelkerling (1983) Seasonal Variation in Standing Crop, Density and Leaf Growth Rate of the Seagrass, Hetereozostera tasmanica, in Western Port and Port Phillip Bay, Victoria, Australia. Aquatic Botany, 16(2), 111-136. Campbell, S. & C. Miller (2002) Shoot and abundance characteristics of the seagrass Heterozostera tasmanica in Westernport estuary (south-eastern Australia). Aquatic Botany, 73, 33-46. CEE (2009) “Port of Hastings. Stage 1 Development. Marine Ecosystem Preliminary Considerations”. Report to AECOM and the Port of Hastings Corporation. CEE Consultants Pty Ltd, Richmond, Victoria. Report, Report authors: Chidgey, S. S., P. F. Crockett, J. Lewis & J. E. Watson. Hall, K. & S. S. Chidgey (2013) Assessing the environmetnal impact of water discharge in a sensitive near-shore marine environment. APPEA Journal. Harris, J. E., J. B. Hinwood, M. A. H. Marsden & R. W. Sternberg (1979) Water Movements, Sediment Transport and Deposition, Western Port, Victoria. Marine Geology, 30, 131-161. MSE (2009) "History of Marine Ecological Monitoring for Cold Strip Mill, 1973-2009, North Arm Channel, Western Port, Victoria." Report to by Marine Science and Ecology to CEE, June 2009. NSR (1974) Natural Systems Research Pty Ltd (1974) Mapping of the seagrass and macrophytic algal communities of Westernport Bay. Project Report for Westernport Bay Environmental Study (1973-1974), Ministry for Conservation, Victoria. Stephens, A. C. (1995) The distribution of seagrass in Western Port, Victoria. . Publication 490. Environmental Protection Authority, Melbourne. Walker, D. I. (2011) "Seagrasses". In: Understanding the Western Port Environment. A summary of current knowledge and priorities for future research. A report published by Melbourne Water. Melbourne VIC 2011. Walker, J. (2003) Western Port Seagrass Restoration Project, 2002: Final Report. In N. H. Trust (ed.). Warry, F. Y. & J. S. Hindell (2009) Review of Victorian seagrass research, with emhasis on Port Phillip Bay.

Western Port Subtidal Seagrass Distribution Study - 2014 42

9 APPENDIX Table 4 Positions of water quality profile sites (light and CTD)

Position (WGS84/MGA, 55H) Site Light Attenuation (m-1) Easting Northing UNA-1 356083 5761603 0.4 UNA-3 355842 5764993 0.35 UNA-4 354488 5762977 0.33 UNA-5 354083 5761879 0.36 UNA-6 352531 5763646 0.37 UNA-7 352415 5762621 0.35 LNA-1 349161 5764088 0.38 LNA-2 347324 5763363 0.36 LNA-3 346558 5762795 0.42 LNA-5 349829 5761895 0.36 LNA-6 348950 5761883 0.37 LNA-7 345677 5761558 0.4 LNA-9 349940 5760539 0.38 LNA-10 349506 5758032 0.33 LNA-11 345043 5757715 0.34 LNA-12 344735 5755649 0.39 LNA-13 348224 5755556 0.3 LNA-14 344600 5754937 0.36 LNA-16 348433 5754648 0.33 LNA-17 344843 5752206 0.28 LNA-18 347388 5751902 0.28 LNA-20 348587 5751892 0.28 LNA-21 345639 5750120 0.28 LNA-22 348609 5750077 0.36 LNA-656 347204 5757746 0.38 LNA-658 347812 5759300 0.36 LNA-676 347582 5759909 0.52 CZ-1 348164 5748088 0.29 CZ-2 346076 5748008 0.23 CZ-3 349411 5746894 0.27 CZ-4 345445 5746585 0.21 RS-1 351135 5745410 0.29 RS-3 352865 5745388 0.37 CS-1 361643 5748584 0.34 CS-4 362196 5750360 0.77

Western Port Subtidal Seagrass Distribution Study - 2014 43

10 APPENDIX. PRELIMINARY SITE INFORMATION REPORT. FEBRUARY 2014

Attachment 2

Prepared for: Port of Hastings Development Authority

Port of Hastings Development Project

APPENDIX North Arm Subtidal Seagrass and Water Quality Monitoring

Preliminary site information February 2014

Port of Hastings Development Project

APPENDIX North Arm Subtidal Seagrass and Water Quality Monitoring

Preliminary site information February 2014

Contents 1 Introduction 1 1.1 This document 1 2 Scope of Work 2 3 Sites investigated 2 4 Methods 3 5 Site descriptions 3 5.1 Joes Island 4 5.1.1 Joes Island Traverse 1 - bathymetry 4 5.1.2 Joe’s Island Traverse 1 Characteristics 5 5.1.3 Joe’s Island Traverse 2 - Bathymetry 6 5.1.4 Joe’s Island Traverse 2 - Characteristics 7 5.2 Quail Island 8 5.2.1 Quail Island - Bathymetry 8 5.2.2 Quail Island - Characteristics 9 5.3 Yaringa 10 5.3.1 Yaringa - Bathymetry 10 5.3.2 Yaringa - Characteristics 11 5.4 Middle Spit 12 5.4.1 Middle Spit - Bathymetry 12 5.4.2 Middle Spit - Characteritics 13 5.5 Tea Tree Point 14 5.5.1 Tea Tree Point - Bathymetry 14 5.5.2 Tea Tree Point - Characteristics 15 5.6 Stony Point 16 5.6.1 Stony Point - Bathymetry 16 5.6.2 Stony Point - Characteristics 17 6 General considerations and recommendation 18

Figures Figure 1. Location of Preliminary site investigations 2 Figure 2. Fishing boats anchored along edge of Middle Spit bank 18 Figure 3. Special marker piles MS1, MS2 and MS 3 in North Arm main channel 19

Port of Hastings Development Project

Report name: “North Arm Subtidal Seagrass and Water Quality Monitoring. Preliminary site information February 2014.”

Report to: Port of Hastings Development Authority

Report prepared by: Scott Chidgey, Peter Crockett and Percival Ho CEE Consultants Pty Ltd PO Box 201 Richmond VIC 3121 [email protected]

Port of Hastings Development Project

Appendix North Arm Subtidal Seagrass and Water Quality Monitoring Preliminary site information

1 INTRODUCTION The Port of Hastings Development Authority (the Authority) is investigating the feasibility of constructing a container terminal at the Port of Hastings. Construction and operation of a container terminal will impact upon the Western Port ecosystem. Construction activities, in particular dredging, and ongoing operations pose obvious risks to water quality in Western Port. Any changes in water quality (such as increased light attenuation) will impact upon the ecosystem, especially the marine vegetation (seagrasses and algae). A detailed understanding of the ecosystem and its function is required to predict likely impacts of the development proposal.

Seagrasses are major habitat forming plants in Western Port and are fundamental to the structure and function of the ecosystem. The current distribution of intertidal and subtidal seagrasses and their environmental dependencies are recognised as priority areas for investigation by the Authority. The current distribution of subtidal seagrasses will reflect the integration of dependencies on seabed type and light, nutrient and current characteristics. Historic data indicates that there is substantial variation in the lower depth limit of subtidal seagrasses between different parts of Western Port. Much of this variation is likely to be due to differences in light attenuation (a product of water quality) around Western Port.

CEE Consultants Pty Ltd (CEE) was commissioned by the Authority to investigate the variation in the lower depth limit of subtidal seagrasses around Western Port. The investigations focusses on the major habitat forming species Zostera nigricaulis and the relationship between water quality (light attenuation) and its lower depth limit. Investigations will include collection of spatial data on seagrass distributions (using towed video) and morphological measures (using limited collection of Zostera material). The results of these investigations are presently being prepared and will be presented in a separate document.

In addition to the depth limit of seagrass, the Authority requested that CEE additionally describe the seabed at five sites that may possibly be used as permanent long-term seagrass and water quality monitoring sites. The information would be used to assess the most appropriate sites for installing water quality logging equipment and monitoring seasonal and longer term variations in key seagrass condition indicators

1.1 This document This document presents the data collected in the preliminary investigations to inform selection of permanent water quality and seagrass monitoring sites.

Appendix 2 North Arm seagrass and water quality monitoring - Preliminary site information

2 SCOPE OF WORK The scope of work was to record the profile of the seabed at a representative location at the site and to document the seabed and vegetation conditions across the seafloor slope.

3 SITES INVESTIGATED The Authority together with marine scientists from CEE identified five possible sites with seagrass that may represent water quality conditions in North Arm ranging from high turbidity in the upper north arm to moderate turbidity in the central area of North Arm to lower turbidity in lower North Arm near the Exchange Segment. The location of the sites was further refined on the basis of knowledge gained during seagrass depth limit investigations and the position of geotechnical drilling sites.

The six sites included  Joes Island in upper North Arm  Quail Island in the northwest of North Arm  Yaringa in the northwest of North Arm  Middle Spit in central North Arm  Tea Tree Point on French Island in the southeast of North Arm and  Stony Point in the southwest of North Arm

The position of the six sites is shown in Figure 1

Figure 1. Location of Preliminary site investigations

Appendix 3 North Arm seagrass and water quality monitoring - Preliminary site information

4 METHODS The bathymetry of the sites was informed by available hydrographic charts, software charts and basemaps prepared by CEE from bathymetric data provided by the Authority.

At each site a video camera with deck display was towed along a track perpendicular to the depth contours. The images from the video tows were recorded and informed the descriptions of the seabed character at each site. The position of the vessel and calibrated water depth were continuously logged at 2 second to 5 second intervals on the GPS and the video record time was synchronised with the GPS time. Positions of seabed features were recorded to deck sheets and waypoints were stored on GPS.

Vessel speed and manoeuvrability was constrained by the video towing cable. Hence tidal currents and wind conditions at the sites affected the track of the vessel.

The data were downloaded and the depth records were corrected for tide height using predicted tide curves for Stony Point.

The six sites were investigated by CEE marine scientists on Friday 24 January 2014.

5 SITE DESCRIPTIONS Summaries of the bathymetric conditions and seabed characteristics at the six sites follow.

Appendix 4 North Arm seagrass and water quality monitoring - Preliminary site information

5.1 Joes Island 5.1.1 Joes Island Traverse 1 - bathymetry 5761500 -1.5

-2

-2.5

-3

-3.5

-4

-4.5 5761450 -5

-5.5 Northing

-6

-6.5

-7

-7.5

-8 5761400 -8.5

-9 356150 356200 356250 356300

Easting Bathymetric chart based on: · CEE field data, 24 January 2014

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are MSL (AHD)

Map Limits: Easting Min 356150 Max 356 300 Northing Min 571400 Max 5761500

Traverse from CEE field data

Appendix 5 North Arm seagrass and water quality monitoring - Preliminary site information

5.1.2 Joe’s Island Traverse 1 Characteristics Depth (m, MSL) Seabed description -2.0 Halophila with sparse Caulerpa and patchy Zostera on sand. -2.25 to -2.5 Dense patch of Zostera with Caulerpa on sand. -2.5 to -3.5 Halophila with sea pens on shelly sand. >-3.5 Sand with sea pens and drift. Shelly at times.

Depth range: -2.0 m to -2.25 m Depth range: -2.25 m to -2.5 m

Depth range: -2.5 m to -3.5 m Depth range: >-3.5 m

Appendix 6 North Arm seagrass and water quality monitoring - Preliminary site information

5.1.3 Joe’s Island Traverse 2 - Bathymetry

Bathymetric chart based on: · CEE field data, 24 January 2014

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are +/-MSL (AHD)

Map Limits: Easting Min 356100 Max 356 200 Northing Min 5761500 Max 5761600

Traverse from CEE field data

Appendix 7 North Arm seagrass and water quality monitoring - Preliminary site information

5.1.4 Joe’s Island Traverse 2 - Characteristics

Depth (m, MSL) Seabed description < -2.7 Sand. Dense Zostera with Halophila and spare Caulerpa on sand. -2.7 to -4.0 Zostera becomes sparse before stopping at -3.3 m. >-4.0 Shelly sand with drift and sparse sea pens.

Depth range: -2 m to -3.3 m Depth range: >-3 m

Appendix 8 North Arm seagrass and water quality monitoring - Preliminary site information

5.2 Quail Island 5.2.1 Quail Island - Bathymetry 5764350 -3

-3.25 5764300 -3.5

-3.75

-4 5764250

-4.25

-4.5 5764200 -4.75

-5

-6 Northing 5764150

-7 -8 5764100 -9

-10

-11 5764050

-12

-13

-14 350100 350200 350300

Easting Bathymetric chart based on: · PoHDA/Cardno data · (from DEPI LiDAR/Multibeam)

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are +/-MSL (AHD)

Map Limits: Easting Min 346800 Max 347400 Northing Min 5763200 Max 5764000

Traverse from CEE field data

Appendix 9 North Arm seagrass and water quality monitoring - Preliminary site information

5.2.2 Quail Island - Characteristics

Depth (m, MSL) Seabed description -2.7 to 3.9 Dense Zostera on sand. -4.4 to -5.4 Patchy Zostera with Halophila on sand. -6.4 to -9.4 Shelly sand with drift Zostera. >-10 Sand with sponges and some drift Zostera.

Depth range: -2.8 m to -3.9 m Depth range: -4.4 m to -5.4 m

Depth range: -6.4 m to -9.4 m Depth range: >-10 m

Appendix 10 North Arm seagrass and water quality monitoring - Preliminary site information

5.3 Yaringa 5.3.1 Yaringa - Bathymetry 5764000 -1

-1.25

-1.5 5763900

-1.75

-2 5763800 -2.25

-2.5

-2.75 5763700 -3

-3.25 -3.5 5763600

-3.75 Northing

-4

-4.25 5763500

-4.5

-4.75 5763400 -5

-6

-7 5763300 -8

-9 -10 5763200 -12 346800 346900 347000 347100 347200 347300 347400 Easting Bathymetric chart based on: · PoHDA/Cardno data · (from DEPI LiDAR/Multibeam)

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are +/-MSL (AHD)

Map Limits: Easting Min 346800 Max 347400 Northing Min 5763200 Max 5764000

Traverse from CEE field data

Appendix 11 North Arm seagrass and water quality monitoring - Preliminary site information

5.3.2 Yaringa - Characteristics

Depth (m, MSL) Notes -1 to -2 Sand. -2 to -3 Sparse Zostera on sand -3 to -4 Dense Zostera with red algae. -4 to -5 Dense Zostera with red algae -5 to -6 Patchy Zostera and Caulerpa. -6 to -7 Patchy Zostera and Caulerpa. -7 to -8 Bare sand with ripples and drift Zostera. Patchy Zostera starts from - -8 to -9 Bare6.5 m. sand with ripples and drift Zostera. -9 to -10 Bare sand with ripples.

Depth range: -2 to -3 m Depth range: -3 to -4 m

Depth range: -5 to -6 m Depth range: -6 to -7 m

Depth range: -7 to -10 m

Appendix 12 North Arm seagrass and water quality monitoring - Preliminary site information

5.4 Middle Spit 5.4.1 Middle Spit - Bathymetry 5756300 -1 -1.25 -1.5 -1.75 -2 -2.25 5756250 -2.5 -2.75 -3 -3.25 -3.5 5756200 -3.75 -4 Northing -4.25 -4.5 -4.75 5756150 -5 -6 -7 -8 -9 5756100 -10 -11 346550 346600 346650 346700 346750 346800 346850 -12 -15 Easting

Bathymetric chart based on: · PoHDA/Cardno data · (from DEPI LiDAR/Multibeam)

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are +/-MSL (AHD)

Map Limits: Easting Min 346550 Max 346850 Northing Min 5756100 Max 5756300

Traverse from CEE field data

Appendix 13 North Arm seagrass and water quality monitoring - Preliminary site information

5.4.2 Middle Spit - Characteristics

Depth (m, MSL) Notes -4.5 Dense Zostera. -4.5 to -7 Very steep bank. -7 to -10 Sand with drift Zostera. Shelly at times. -11 to -12 Bare sand with ripples.

Depth range: -4.5 m Depth range: -7 m to -10 m

Depth range: -11 m to -12 m

Appendix 14 North Arm seagrass and water quality monitoring - Preliminary site information

5.5 Tea Tree Point 5.5.1 Tea Tree Point - Bathymetry

5749600 -1.75

-2

-2.25

-2.5

-2.75 5749550

-3

-3.25

-3.5

-3.75

-4 5749500

-4.25 Northing -4.5

-4.75

-5

-6 5749450

-6.5

-7

-8

-10

-15 348600 348700 348800 Easting

Bathymetric chart based on: · PoHDA/Cardno data · (from DEPI LiDAR/Multibeam)

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are +/-MSL (AHD)

Map Limits: Easting Min 348550 Max 356850 Northing Min 5749400 Max 5749600

Traverse from CEE field data

Appendix 15 North Arm seagrass and water quality monitoring - Preliminary site information

5.5.2 Tea Tree Point - Characteristics

Depth (m, MSL) Notes -2 to -3 Halophila with patchy Caulerpa and red algae on sand. -3 to -4.5 Dense Zostera with Halophila and red algae on sand. -4.5 to -5 Halophila on sand. -5 to -7 Sparse Zostera with drift on sand. -7 to -9 Bare sand with a lot of drift and sparse sponges.

Depth range: -2 m to -3 m Depth range: -3 m to -4.5 m

Depth range: -4.5 m to -5 m Depth range: -7 m to -9 m

Appendix 16 North Arm seagrass and water quality monitoring - Preliminary site information

5.6 Stony Point 5.6.1 Stony Point - Bathymetry 5752750 -1

-1.25

-1.5

-1.75

-2

-2.25 -2.5 5752650 -2.75

-3

-3.25

-3.5

-3.75 Northing

-4 -4.25 5752550 -4.5

-4.75

-5

-6

-7

-10 -15 5752450 344500 344600 344700 Easting

Bathymetric chart based on: · PoHDA/Cardno data · (from DEPI LiDAR/Multibeam)

Positions are WGS84/MGA94 Zone 55

Depths/Elevations are +/-MSL (AHD)

Map Limits: Easting Min 344500 Max 344700 Northing Min 5752450 Max 5752750

Traverse from CEE field data

Appendix 17 North Arm seagrass and water quality monitoring - Preliminary site information

5.6.2 Stony Point - Characteristics

Depth (m, MSL) Notes -1.8 to -7.3 Dense Zostera before becoming dense Halophila at -7 m. -7.3 to -8.3 Sparse Zostera with Halophila on silt. -8.3 to -9.3 Shelly silt with a lot of drift Zostera. -9.3 to -10.2 Shelly silt with drift Zostera.

Depth range: -1.5 m to -7 m Depth range: -7 m

Depth range: -7 m to -8 m Depth range: -8 m to -9 m

Depth range: -9 m to -10 m

Appendix 18 North Arm seagrass and water quality monitoring - Preliminary site information

6 GENERAL CONSIDERATIONS AND RECOMMENDATION The permanent monitoring sites should be located where:  There is abundant seagrass nearby that has its lower boundary limited by light;  There is little risk of the monitoring instruments being fouled by anchors and lines from boating anglers;  The instruments can be securely installed in an upright position;  The vertical distance between top and bottom light loggers should be approximately 5 m;  Top light loggers should be approximately 2 m below low tide mark.

The investigations so far show that extensive subtidal seagrass beds grow to their lower limit at relatively few locations. The major area for subtidal seagrass identified so far appears to be the area of gently sloping seabed on the northwest of North Arm from BlueScope to approximately the Yaringa Channel (including the Yaringa site).

Seagrass at most other sites appears to be depth limited by seabed form and hydrodynamic factors. The seagrass lower limit is characterized by a sharp and often undercut steepening of the seabed slope.

Recreational anglers were observed anchored at along the edge of the steeper slopes of the banks including Joe’s Island, Middle Spit and Stony Point. It is likely that the anglers have preferred locations to fish which depend on a range of factors including wind strength and direction and tide condition.

Figure 2. Fishing boats anchored along edge of Middle Spit bank

It is apparent that there are unlikely to be sites that suit all the prerequisites for installing monitoring equipment directly onto the seabed. However, it was observed that three Special Marker Piles are installed along 6 km of the eastern boundary of the shipping area in North Arm. The steel marker piles are positioned in water depths greater than

Appendix 19 North Arm seagrass and water quality monitoring - Preliminary site information

10 m and are fitted with navigation markers and lights, access ladders, protected platform and solar panel (Figure 3).

. Figure 3. Special marker piles MS1, MS2 and MS 3 in North Arm main channel

Water quality monitoring instruments could be installed safely and securely at two depths on the northern side of one or several of the piles. The instrument readings could be telemetered directly to the Authority offices. The benefits of telemetered results are: (1) real time information on condition in the North Arm; (2) continuous records logged securely in on-land computer storage; (3) continuous checks on instrument readings and data quality; (4) rapid maintenance of instruments without prolonged loss of data; (5) reduced reliance on internal battery and logger storage between maintenance checks, and; (6) greatest likelihood of data continuity and quality.

The logged data could be supplemented with monthly profiles of water quality at numerous locations around the Bay to provide information on spatial patterns, with short term deployments of other water quality loggers at select locations to provide information on local scale temporal variation.

Attachment 3

Report to: Port of Hastings Development Authority

Port of Hastings

Seagrass Monitoring Pilot Study

June 2014

Port of Hastings: Seagrass Monitoring Pilot Study i

Table of Contents

1 Background 1 1.1 Objectives 1 1.2 Pilot study development 1 1.3 Chosen methods 3 1.4 Outputs 4 1.5 Seagrass taxonomy 5

2 Methodology 6 2.1 Site selection 6 2.2 Field methods 8 2.2.1 Subtidal Zostera nigricaulis depth limit 8 2.2.2 Sedimentation 8 2.2.3 Seagrass sampling 9 2.3 Laboratory methods 10 2.3.1 Sorting and measuring 11 2.3.2 Biomass 11

3 Results 12 3.1 Biomass 12 3.1.1 Zostera nigricaulis 12 3.1.2 Other macrophytes 15 3.1.3 Macrophyte community biomass 16 3.2 Shoot density 17 3.3 Shoot morphology 19 3.4 Leaf Morphology 22

4 Results Summary 24

5 Discussion 25 5.1 Biomass 25 5.2 Shoot density 25 5.3 Shoot morphology 25 5.4 Leaf morphology 25

Port of Hastings: Seagrass Monitoring Pilot Study ii

Figures Figure 1 Taxonomic name changes for key Western Port seagrass species 5 Figure 2 Study locations – North Arm Western Port 7 Figure 3 Method for marking Z. nigricaulis lower depth limit 8 Figure 4 Diver installing sedimentation tube (left) and diagram (right) 8 Figure 5 Diver sampling Z. nigricaulis using quadrat cube 9 Figure 6 Flowchart for laboratory tasks 10 Figure 7 Above ground Z. nigricaulis biomass 12 Figure 8 Average Zostera stem biomass 13 Figure 9 Average Zostera leaf biomass 13 Figure 10 Zostera detritus biomass 14 Figure 11 Epiphytic macroalgae biomass 15 Figure 12 Whole macrophyte community biomass 16 Figure 13 Regression of macrophyte community biomass versus depth 16 Figure 14 Density of mature Zostera shoots 17 Figure 15 Density of new Zostera shoots 17 Figure 16 Density of Zostera rafting shoots 18 Figure 17 Density of Zostera nigricaulis shoots with multiple leaf clusters 18 Figure 18 Median Zostera nigricaulis shoot length 19 Figure 19 Regression of median shoot length versus depth 19 Figure 20 Median stem length (dark shading) and leaf length (light shading) 20 Figure 21 Median Zostera nigricaulis leaves per shoot 20 Figure 22 Regression of median leaves per shoot versus depth 21 Figure 23 Average Zostera nigricaulis node number per stem 21 Figure 24 Median Zostera nigricaulis leaf length 22 Figure 25 Regression of leaf length versus depth 22 Figure 26 Median Zostera nigricauls leaf width 23 Figure 27 Median Zostera nigricauls leaf thickness 23 Figure 28 Leaf median width to median thickness ratio 23

Tables Table 1 Seagrass metrics and their utility as indicators of plant and meadow condition 4 Table 2 Potentially useful seagrass physiology metrics 4 Table 3 Seagrass monitoring site positions 6

Report to: Port of Hastings Development Authority

Report by: Scott Chidgey and Peter Crockett

CEE Consultants PO Box 201 Richmond VIC 3121 [email protected] www.cee.com.au

Cover photo: Zostera nigricaulis and red macroalgae epiphytes at Inside Channel

Port of Hastings Seagrass Monitoring Pilot Study DRAFT 1 Background CEE was engaged by the Port of Hastings Development Authority to conduct a pilot study trialling subtidal seagrass monitoring methods and documenting existing subtidal seagrass conditions.

1.1 Objectives The pilot study was developed to achieve the following objectives: • Develop subtidal seagrass sampling and sample processing methods appropriate for the Western Port environment • Document existing spatial and temporal variation in subtidal seagrass abundance and extent • Document existing spatial and temporal variability in seagrass morphological metrics (morphometrics) • Establish relationships between spatially and temporally variable environmental factors (light, seabed, water quality) and seagrass extent and morphometrics • Determine the metrics that show the strongest relationships to environmental factors and hence; • Select the most appropriate indicators of subtidal seagrass condition

Results relevant to the following objectives are available following the first (Autumn 2014) survey: • Develop sampling and sample processing methodology • Document existing spatial variability in seagrass morphological metrics • Establish relationships between spatially variable environmental factors (depth, light, geography) • Determine metrics that show the strongest relationships to environmental factors

1.2 Pilot study development Seagrass meadows are one of the most thoroughly studied marine ecological communities. There is a large amount of literature that documents seagrass research methods, informative metrics of seagrass health and responses of seagrasses to various environmental stressors or changes.

The following key references informed the development of seagrass monitoring methods described and implemented in the pilot study.

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 2

Key publications of seagrass research in Western Port Blake, S. and D. Ball (2001). Victorian Marine Habitat Database: Seagrass Mapping of Western Port. Queenscliff, Marine and Freshwater Resources Institute. Bulthuis, D. A. (1983). "Effects of in situ light reduction on density and growth of the seagrass Zostera tasmanica (Martens ex Aschers.) den Hartog in Western Port, Victoria, Australia." Journal of Experimental Marine Biology and Ecology 67(1): 91-103. Bulthuis, D. A. and W. J. Woelkerling (1983). "Seasonal variation in standing crop, density and leaf growth rate of the seagrass, Zostera tasmanica, in western Port and Port Phillip Bay, Victoria, Australia." Aquatic Botany 16: 111-136. Campbell, S. J. and C. J. Miller (2002). "Shoot and abundance characteristics of the seagrass Zostera tasmanica in Westernport estuary (south-eastern Australia)." Aquatic Botany 73(1): 33-46. CEE (2014) North Arm Subtidal Seagrass and Water Quality Monitoring. Spatial variation in subtidal seagrass depth limits in Western Port, February 2014. Report to Port of Hastings Development Authority. Miller, C. J., S. J. Campbell, et al. (2005). "Spatial variation of Zostera tasmanica morphology and structure across an environmental gradient." Marine Ecology Progress Series 304: 45-53. Stephens, A. W. (1995). The Distribution of Seagrasses in Westernport, Victoria. Melbourne, Environment Protection Authority. York, PH & Smith TM (2013) Research, monitoring and management of seagrass ecosystems adjacent to port developments in central Queensland: Literature Review and Gap analysis. Deakin University, Waurn Ponds, Victoria

Key publications on seagrass monitoring relevant to Western Port Bulthuis, D. A. (1983). "Effects of in situ light reduction on density and growth of the seagrass Zostera tasmanica (Martens ex Aschers.) den Hartog in Western Port, Victoria, Australia." Journal of Experimental Marine Biology and Ecology 67(1): 91-103. Bulthuis, D. A. and W. J. Woelkerling (1983). "Seasonal variation in standing crop, density and leaf growth rate of the seagrass, Zostera tasmanica, in western Port and Port Phillip Bay, Victoria, Australia." Aquatic Botany 16: 111-136. Chartrand KM, Ralph PJ, Petrou K and Rasheed MA. (2012) Development of a Light- Based Seagrass Management Approach for the Gladstone Western Basin Dredging Program. DAFF Publication. Fisheries Queensland, Cairns 126 pp. Lee, D. (2010) Seagrass Monitoring Program Detailed Design, Port of Melbourne Corporation. (Channel Deepening Project) McMahon, K., C. Collier, et al. (2013). "Identifying robust bioindicators of light stress in seagrasses: A meta-analysis." Ecological Indicators 30: 7-15.

Bulthuis (1983) and Bulthuis and Woelkerling (1983) conducted early studies on intertidal Zostera seagrass in Western Port and some of the only existing studies on subtidal Zostera seagrass in Western Port. Their methods relied on both field and laboratory based measurements of seagrass metrics including biomass, density, shoot morphology and growth rates. These projects required large numbers of personnel for field and laboratory tasks.

Lee (2010) documents the monitoring methods used from 2008 to 2011 during the Port Phillip Bay Channel Deepening Project (PoMC). This monitoring program exclusively used in-situ sampling. Three seagrass parameters were monitored in intertidal and subtidal seagrass beds: • Seagrass cover (%)

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• Shoot length • Shoot density Incidental qualitative observations of desiccation (intertidal), spadices (flowering) and epiphytes and drift algae were made. The program collected quarterly (seasonal) data over several years documenting substantial seasonal and interannual variations in the three parameters monitored. CEE understands that the in-situ sampling was relatively time consuming, with surveys at each site requiring around 1-2 hours in the water from two divers.

Chartrand et al (2012) establish minimum light requirements for seagrass in Gladstone and develop trigger values for performance limits as part of an adaptive dredging management plan.

McMahon et al (2013) details a broad range of indicators that can be used when monitoring seagrasses for responses to light availability. Their documentation of useful indicators is based on review of a large literature on multiple species. These indicators range from chloroplast scale metrics (photosynthetic efficiency, carbon capture) to meadow-scale metrics (density, biomass). The different indicators are suited to monitoring responses over different time scales.

CEE has considered the above references in the development of the pilot program, described below.

1.3 Chosen methods CEE considers that monitoring of subtidal seagrass in Western Port is best achieved by limited destructive sampling. This is because: • Water clarity in Western Port generally precludes in-situ visual methods for taking seagrass measurements (shoot counts, shoot lengths, cover etc) • Occasionally high abundances of macroalgal epiphytes can also preclude in- situ visual data collection. • In-situ (field) measurement of seagrass metrics are more time consuming than laboratory methods, an important consideration in Western Port where field site access is constrained by both tide and weather. • Collection of small seagrass samples is a quick, simple and easily replicated procedure requiring minimal training of divers • Collection of seagrass samples allows laboratory determination of a wide range of parameters, including biomass and morphological parameters that are not practical for field measurement.

The indicators included in the current pilot study are tabulated below (Table 1), after McMahon et al (2013), to show their applicability and provide an indication of cost.

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 4

Table 1 Seagrass metrics and their utility as indicators of plant and meadow condition

Timescales of response Considerations for use Indicator utility Early warning Long term Days Weeks Months Years Collect Process Interpret  Lab Leaf length Leaf width  Lab Leaf thickness  Lab Leaves per  Lab shoot Plant scalePlant (Growth and morphology) New shoots  Lab Rafting shoots  Lab Above-ground  Lab biomass

Shoot density  Lab Leaf density  Lab Macroalgae  Lab biomass Halophila  Lab biomass Meadow Scale Sedimentation Field Lab Meadow Field Field depth limit 3-4 1.5 hrs sites per per 2 days sample Current program time requirements day per 2 days 54 hours survey per per survey survey

The possibility of including physiological metrics that are able to measured easily in the field or laboratory has been proposed. While not included in the current program their utility is presented in Table 2 Table 2 Potentially useful seagrass physiology metrics

Timescale of response Considerations for use Indicator utility Early warning Long term Days Weeks Months Years Collect Process Interpret Light harvesting Field efficiency Photosynthetic Field rate Rhizome sugars  Lab

1.4 Outputs The end-use of the data includes: • Informing the design of ongoing monitoring programs by documenting existing variation in seagrass metrics at a variety of spatial and temporal scales • Establish ‘trigger-values’ for seagrass metrics (such as light levels at which seagrass persistence is threatened) • Input to predictive models of Port of Hastings development effect on marine ecosystem components

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 5

1.5 Seagrass taxonomy The scientific names of seagrasses is currently under review. Classical systematic descriptors of seagrasses are being supplemented with modern genetic technique analyses. This is resulting in the confirmation of some seagrass taxa and the redefinition of others. Two key seagrass species that occur in Western Port can be separated on physical characteristics. However, as shown below, the scientific names of Zostera muelleri and Zostera nigricaulis that were proposed in 2009 (after a range of combinations since 1933) may change again in the near future due to genetic similarities to other genera. The names Zostera muelleri and Zostera nigricaulis will be used for the purposes of this report.

Figure 1 Taxonomic name changes for key Western Port seagrass species 4 can be muelleri 2013 capricorni nigricaulis tasmanica N. muelleri N. H. 1995 H. . tasmanica Z. Z. capricorni Z Zostera, , , Heterozostera , , Nanozostera based based on cortical vascular and , , & , , has (2001) suggest (2001) suggest four genera for rhizome rhizome Phyllospadix (1995) nomenclature is current (for the time being) time the (for current is nomenclature : Zostera (2001) state (2001) state Zostera Zostera Zosteraceae samples: samples: 009 -Pottruff data from data 90 Phyllospadix Heterozostera using molecular the Nanozostera growth and and growth Posluzny Coyer et al (2013) al Coyer et with find four genera in reproductive reproductive demonstrate Heterozostera Soros Posluszny Hartog occur in Western Port) in Western occur Heterozostera structures consistent monopodial Zosteraceae bundles, undulating rhizome, wiry stems. based on molecular and morphological evidence) ( Kuo & den differentiated from differentiated Tomlinson and - 2009 nigricaulis capricorni Z. muelleri Z. muelleri Z. nigricaulis Z. 1970 Z. tasmanica Z. Z. Z. Z. capricorni H. tasmanica H. muelleri 2001 Z. and and Z. capricorni H. tasmanica H. and Zostera east Australian ZOSTERACEAE Australian - east data Hartog Zostera genus under Heterozostera Jacobs and Les (2009) combine (2009) combine using molecular based on based and morphology den (sympodial) muelleri Heterozostera rhizome growth (1970) describes (1970) describes Design discussion for Zostera samples nigricaulis H. into Zostera CEE CEE Seagrass PilotMonitoring Study muelleri 2003 nigricaulis Z. Z. capricorni H. H. tasmanica H. muelleri Heterozostera 1933 not yet recognised. Z. Les et al (2002) sinking sinking (2002) al et Les Z. capricorni Z. tasmanica Heterozostera four based on morphological and genetic genetic Base data. analysis on NSW). Note Note that NSW). only (three only from from(three WA, one in , , Chilensis Zostera Heterozostera nigricaulis polychlamys genus (1933) first (2005) describes - H. Note: Coyer et al (2013) finding not yet recognised by accepted authorities (Algaebase.org or MarineSpecies.org), therefore 2 therefore MarineSpecies.org), or (Algaebase.org authorities accepted by recognised finding yet not al (2013) et Coyer Note: muelleri H. 2002 and H. H. and sub Z. genus Kuo Z. capricorni Heterozostera H. tasmanica H. based based on cortical vascular bundles, bundles, vascular proposes separate separate proposes Setchell leaving leaving in it Chronological taxonomy of south taxonomy Chronological 2003 muelleri 1933 capricorni - Zostera Z. muelleri Z. H. tasmanica H. Z. based on proposed Pre Z. capricorni ecombining Z. tasmanica Tanaka et Tanaka et al with r combination combination Heterozostera (2003) suggest (2003) suggest (Our current understanding is that (Our understanding current genetics, no new

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 6

2 Methodology 2.1 Site selection Four monitoring locations were selected throughout North Arm. Locations at Inside Channel, Yaringa and Tea Tree Point were paired with already established water quality monitoring sites. An additional location at Stony Point was also selected.

Monitoring locations and sites were selected to be representative of: a) broad scale spatial variation in water quality and habitats in North Arm b) broad scale (water quality related) and small scale (depth related) variation in light availability.

A single shallow subtidal monitoring site was established at Inside Channel. Subtidal seagrass is here limited to a narrow depth range on a steeply sloping seabed. The site established was positioned at 3.1 m below MSL. This site was chosen to represent habitat and water quality conditions representative of Upper North Arm.

Three monitoring sites were established at Yaringa where seagrass beds extend from the intertidal to the subtidal along gently sloping seabed. The three sites were positioned at different depths: 3.0 m below MSL (intertidal), 4.2 m below MSL (shallow subtidal) and 6.2 m below MSL (subtidal Zostera limit). These sites were selected to allow straight-forward comparison between sites of consistent water quality but different depths (hence light availability). Habitat and water quality conditions are intermediate between the Upper North Arm and Lower North Arm.

A single shallow subtidal monitoring site was established at Tea Tree Point. Extensive seagrass is present in shallow subtidal water on moderately sloping seabed. The site was established at 4.5 m below MSL, just above the subtidal limit of Zostera. While there is flat seabed in shallower water, Zostera is sparse and patchy.

A single intertidal monitoring site was established at Stony Pt. Extensive intertidal seagrass is present at Stony Point behind a slightly raised ridge of overwash sand. The site was established at 1.2 m below MSL. There is a narrow band of shallow subtidal seagrass on steeply sloping seabed seaward of the ridge of overwash sand.

Both the Stony Point and Tea Tree Point sites have habitat representative of Lower North Arm. Water quality is intermediate between Lower North Arm and the Confluence Zone.

GPS position data for each site are shown below in Table 3 and a map of the locations is shown in Figure 2.

Table 3 Seagrass monitoring site positions

Site Easting Northing Latitude Longitude Location (depth) WGS84, 55 H AGD 94 Inside Channel 3.1 m 356183 5761489 -38.28315 145.35566 Yaringa 6.2 m 347078 5763397 -38.26446 145.25201 4.2 m 346869 5763454 -38.26391 145.24963 3.0 m 346629 5763508 -38.26338 145.24690 Stony Point 1.2 m 344553 5752358 -38.36347 145.22073 Tea Tree Point 4.5 m 348649 5749473 -38.39016 145.26697

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 7

Figure 2 Study locations – North Arm Western Port

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2.2 Field methods The initial monitoring survey was conducted between 14 and 16 May 2014. At each site an area of continuous Zostera nigricaulis was selected. Sites were marked out with white stakes at each corner. Each site measures approximately 10 m by 10 m. The centre of each site was recorded using GPS.

2.2.1 Subtidal Zostera nigricaulis depth limit Three sites were positioned just above the lower depth limit of subtidal Z. nigricaulis (Inside Channel, Yaringa (5.5 m) and Tea Tree Pt). At these sites the existing lower depth limit was marked by white stakes at intervals of 2-3 metres (Figure 3).

In subsequent visits the distance between the stakes and the seagrass bed edge will be measured to determine whether there has been an advance or contraction.

Figure 3 Method for marking Z. nigricaulis lower depth limit

2.2.2 Sedimentation Sedimentation tubes were installed at the three sites adjacent to the Zostera lower depth limit (Inside Channel, Yaringa, Tea Tree Pt). Two tubes were installed at each site, secured to a stake driven into the seabed. Tubes were constructed from 30 mm diameter PVC pipe with a cap secured at each end. Each tube was 500 mm long. The uppermost 250 mm of the tube was perforated with twenty 12 mm diameter holes to allow water to move through the tube with minimal turbulence. The lower 250 mm of the tube functions as a ‘stilling’ chamber to collect settling sediment.

In subsequent visits the tubes will be retrieved, the accumulated sediment removed for drying and weighing, and the tubes reinstalled.

Figure 4 Diver installing sedimentation tube (left) and diagram (right)

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2.2.3 Seagrass sampling Six 0.0625 m2 samples of Z. nigricaulis and associated macrophytes were collected from each site. Other macrophytes found within Z. nigricaulis beds include epiphytic seaweeds, Halophila ovalis seagrass and the seaweed Caulerpa cactoides. A quadrat cube was used to mark the 0.0625 m2 area (0.25 m by 0.25 m by 0.2 m, see Figure 5).

Quadrats were positioned haphazardly along a 10 m transect through the middle of the site. The ends of the transect were marked by stakes to guide sampling in subsequent surveys (preventing re-sampling of previously cleared plots).

Zostera shoots and other macrophytes rooted within the quadrat were gently drawn up through the quadrat and shoots rooted outside the quadrat were carefully moved away from the quadrat. All material was then removed at the seabed and gently placed in a 2 mm diameter mesh bag.

Back on the boat each sample was transferred to a large plastic bag and kept cool and dark during transport.

Figure 5 Diver sampling Z. nigricaulis using quadrat cube

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2.3 Laboratory methods Samples were stored frozen prior to processing. Samples were defrosted immediately prior to sorting and measuring. The following flow chart details laboratory methods (Figure 6).

Figure 6 Flowchart for laboratory tasks

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2.3.1 Sorting and measuring Samples were sorted into live (intact) Z. nigricaulis material, Z. nigricaulis detritus, macroalgal epiphytes, Halophila ovalis and Caulerpa cactoides material.

The following measurements and counts were made on Z. nigricaulis material (also see Figure 6): • Number of mature shoots per quadrat (shoots with a lignified, black stem) • Number of new shoots per quadrat (shoots with a non-lignified stem) • Number of ‘rafting shoots’ per quadrat (reproductive shoots sprouting from the apices of mature shoots) • Overall length of up to 50 shoots per sample • On each of 6 shoots randomly selected from each sample: o Overall shoot length o Number of leaf clusters per shoot o Number of leaves per shoot o Leaf lengths (including sheath) o Stem length o Number of nodes per stem o Width and thickness of a mature leaf from each shoot, measured in the lower half of the leaf.

Shoot, stem and leaf lengths were measured to the nearest millimetre. Leaf widths and thicknesses were measured to the nearest 0.01 mm with the assistance of a dissecting microscope. 2.3.2 Biomass Sorted damp samples were placed in perforated paper bags for drying. The damp- weight of each sample was recorded then samples were dried to constant weight in a heated, ventilated cabinet. The net dry-weight biomass of each sample was recorded.

Sample weights were measured to the nearest 0.005 g.

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3 Results Results from the first monitoring survey in Autumn (May) 2014 are presented in the following sections. All error bars are standard error of the mean.

Linear regressions of morphological parameters versus depth are shown where an r2 value of 0.40 or greater was achieved. Depth is used as a surrogate for light availability. When light availability data becomes available for the sites, seagrass biomass and morphological variables can be related directly to light availability, which is more ecologically relevant.

3.1 Biomass All biomass results are reported as grams dry weight per square metre.

Zostera nigricaulis had the highest biomass of any macrophyte at each site. Other macrophytes contributed substantial biomass at all sites. The sections below present biomass results for Zostera, epiphytic macroalgae, Caulerpa cactoides and Halophila ovalis.

3.1.1 Zostera nigricaulis The above ground biomass of Z. nigricaulis (Figure 7) was highest at the shallow Yaringa site (3 m depth) and lowest at the Inside Channel site (3.1 m depth). The three sites at Yaringa showed a clear decrease in biomass as depth (and light availability) increased.

160 140 120 100 (g dry weight) 2 80 60 40

Biomass perm 20 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 7 Above ground Z. nigricaulis biomass

Regressions of Z. nigricaulis above ground biomass versus shoot density, leaf density and leaf area showed that biomass was most strongly related to median leaf area per m2 (r2 = 0.66); somewhat related to shoot density (r2 = 0.57) and; weakly related to leaf density (r2 = 0.46). Above ground biomass is therefore mostly determined by the product of leaf number, length and width.

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Patterns in both stem (Figure 8) and leaf (Figure 9) biomass closely followed that of total above ground biomass (Figure 7).

70

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40 (g dry (g weight) 2 30

20 Biomass/m 10

0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 8 Average Zostera stem biomass

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0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 9 Average Zostera leaf biomass

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Zostera nigricaulis detritus biomass is shown below in Figure 10. ‘Detritus’ was classified as any stem material without live leaves or any loose and dead (brown) leaf material. Detritus was mostly stem material, but would have included a small amount of live material that is inevitably damaged during sample sorting (ie, broken stem bases). Zostera nigricaulis detritus was included in the total above ground Z. nigricaulis biomass: 70

60

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40 (g dry weight) 2 30

20

Biomass/m 10

0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 10 Zostera detritus biomass

Linear regressions of depth versus Zostera total above ground, stem, leaf or detritus biomass returned r2 values of less than 0.2. This does not provide evidence for a relationship between depth and Zostera biomass, though data from Yaringa indicates that this may be the case in some locations.

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3.1.2 Other macrophytes Epiphytic macroalgae (seaweed) biomass is shown below in Figure 11. Epiphyte biomass was highest at the shallowest site at Stony Point (59 g m2), followed by Inside Channel (37 g DW/m2). Field observations recorded noticeably abundant epiphytes at both these sites, particularly at Stony Pt. Epiphytes at Inside Channel comprised mostly red algae species while at Stony Pt both red and filamentous brown algal epiphytes were abundant. The lowest epiphyte biomass was seen at the deepest Yaringa site (6.2 m depth, 10 g DW/m2). 180

150

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60 Biomass/m 30

0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 11 Epiphytic macroalgae biomass

Some Caulerpa cactoides was collected at the Stony Point intertidal site where it had an average biomass of 42.2 g DW/m2.

Halophila ovalis was collected at the Inside Channel and Tea Tree Point sites. These sites had Halophila biomasses of 11.7 and 3.8 g DW/m2 respectively. At both sites Halophila formed a discontinuous and variable density understorey to Z. nigricaulis.

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3.1.3 Macrophyte community biomass While Zostera is the main ‘habitat forming’ species at each site, all macrophytes contribute to primary production and provision of habitat. Therefore it is important to consider the biomass of the community as a whole as well as that of individual components. Macrophyte community biomass is shown below in Figure 12.

Stony Point had the highest macrophyte biomass (202 g DW/m2) and the deep Yaringa site the lowest (75 g DW/m2). The chart shows that macrophyte community biomass follows differences in depth, and therefore light availability, with shallower sites having higher, and deeper sites lower, biomass.

240 210 180 150 (g weight) dry

2 120 90 60 30

Biomass perm 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 12 Whole macrophyte community biomass

A linear regression of whole macrophyte community biomass versus depth is shown below in Figure 13. The regression returned an r2 value of 0.44. This result is consistent with the logical positive relationship between light availability and macrophyte biomass.

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250 y = -23x + 224 200 R² = 0.44 150

100 Dry weight Dry (g) 50

0 1 2 3 4 5 6 Depth (metres below MSL)

Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 13 Regression of macrophyte community biomass versus depth

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3.2 Shoot density The density of mature shoots (shoots per m2) is shown below in Figure 14. Mature shoot density was highest at Stony Point and lowest at the deep Yaringa site. Mature shoot densities related to depth at Yaringa – with higher densities in shallow depths with higher light availability. Mixed patterns were seen elsewhere – with relatively high densities seen at the second deepest site at Tea Tree Pt (note that this site has higher water clarity than northern areas of North Arm).

1600 1400 1200 2 1000 800 600 Numberper m 400 200 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 14 Density of mature Zostera shoots

The density of new Zostera shoots is shown in Figure 15. The highest density of new shoots was seen at the Stony Point intertidal sites and the lowest at the deep Yaringa site and Tea Tree Point site. The data do not show strong patterns relating to depth.

500 450 400

2 350 300 250 200

Numberper m 150 100 50 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 15 Density of new Zostera shoots

The density of rafting Z. nigricaulis shoots is shown in Figure 15. The highest density of rafting shoots was seen at the Stony Point and Yaringa intertidal sites, closely

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 18 followed by the Tea Tree Point site. No rafting shoots were seen at the deeper Yaringa site, though some were seen at Inside Channel. The data show that this mode of reproduction may be more common in intertidal Zostera beds but that it is by no means confined to intertidal beds.

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Figure 16 Density of Zostera rafting shoots

The density of Z. nigricaulis shoots with multiple leaf clusters is shown below in Figure 17. The highest densities were seen at the shallower sites, none were recorded at the deepest site (Yaringa, 6.2 m). 300 2 - 250

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Shoots with multiple clusters/m 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 17 Density of Zostera nigricaulis shoots with multiple leaf clusters

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3.3 Shoot morphology Data on a number of shoot, stem and leaf morphological metrics are presented below.

Median Z. nigricaulis shoot length is shown in Figure 18. The longest shoots were seen at the deep Yaringa site, and the shortest at the Stony Point intertidal site. There was a positive linear relationship between shoot length and depth (Figure 19, r2 = 0.56), with longer shoots seen at deeper sites. Shoots at the shallowest Yaringa site were notably just as long as those at the nearby 4 m site, indicating that shoot length is not solely related to depth.

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0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 18 Median Zostera nigricaulis shoot length

700 600 500 400 300 200 y = 50x + 245 Shootlength (mm) R² = 0.56 100 0 1 2 3 4 5 6 Depth (metres below MSL)

Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 19 Regression of median shoot length versus depth

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The median stem and leaf length measured at each site is shown in Figure 20. Stem and leaf length co-vary – that is, shoots with longer stems also have longer leaves and vice versa. Median leaf length was on average around 73 percent of median stem length except at Inside Channel where leaf length matched stem length.

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Stem and leaf length (mm) 100

0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 20 Median stem length (dark shading) and leaf length (light shading)

The median number of leaves per Z. nigricaulis shoot at each site is shown below in Figure 21. The highest number of leaves was seen at the Stony Point intertidal site and the lowest at the deep Yaringa site. A linear regression (Figure 22) showed there is a negative relationship between leaf number and depth (r2 = 0.66) – shallower sites with more light have a higher number of leaves per shoot.

8 7 6 5 4 3 2 Median leaves per shoot 1 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 21 Median Zostera nigricaulis leaves per shoot

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8 7 6 5 4 3 y = -0.59x + 7.4

Leaves pershoot 2 R² = 0.66 1 0 1 2 3 4 5 6 Depth (metres below MSL)

Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 22 Regression of median leaves per shoot versus depth

The median number of nodes per stem on Z. nigricaulis stems at each site is shown below in Figure 23. Nodes indicate where leaves have been produced (one leaf is produced at each node (Bulthuis, 1983). In grasses such as seagrass, the time between production of two leaves is known as the plastochrone interval. If the plastochrone interval can be estimated, the number of nodes can be used to measure stem age.

The number of nodes on each stem did not differ appreciably between sites. Bulthuis (1983) found that leaf growth rates did not differ appreciably under different light regimes. However, Bulthuis found that leaf cluster density was significantly lower in lower light, which is consistent with the results of the 2014 data. Assuming leaf growth rates are the same across all depths, it is apparent that shoots at all depths are similar in age. These assumptions should be validated by new measurements of growth rates to be defensible. 25

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0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 23 Average Zostera nigricaulis node number per stem

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3.4 Leaf Morphology The median length of Z. nigricaulis leaves is shown below in Figure 24. The longest leaves occurred at the deepest site (Yaringa, 6.2 m) and the shortest leaves occurred at the shallowest site (Stony Pt, 1.2 m). The linear regression showed a positive relationship between leaf length and depth (Figure 25, r2 = 0.63). Deeper sites with lower light availability have longer leaves and vice-versa. This pattern was particularly evident between the Yaringa sites.

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0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 24 Median Zostera nigricaulis leaf length

350 300 250 200 150 100 y = 23x + 107 leaf leaf length (mm) R² = 0.63 50 0 1 2 3 4 5 6 Depth (metres below MSL)

Inside Channel Yaringa Stony Pt Tea Tree Pt

Figure 25 Regression of leaf length versus depth

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Median leaf width and thickness are shown below in Figure 26 and Figure 27. There are no distinct depth related patterns when these metrics are viewed in isolation. 2.0

1.5

1.0

0.5 Leaf (mm)width 0.0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 26 Median Zostera nigricauls leaf width

0.10 0.08 0.06 0.04 0.02 Leaf thickness(mm) 0.00 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 27 Median Zostera nigricauls leaf thickness

The ratio of leaf width to thickness at each site is shown below in Figure 28 and does appear to relate to depth. The ratio was highest at the two deepest sites (Tea Tree Pt, 4.5 m and Yaringa, 6.2 m) and lowest at Stony Pt (1.2 m). At Yaringa, the ratio increased with depth, indicating leaves become wider and/or thinner with depth, or decreased light availability. 0 0 0 0 0 0 0 0 0 0 Leaf : widththickness ratio 0 3.1 6.2 4.2 3.0 1.2 4.5 Inside Yaringa Stony Pt Tea Tree Pt Channel

Figure 28 Leaf median width to median thickness ratio

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 24

4 Results Summary • Zostera above-ground biomass ranged between 58 (Inside Channel) and 140 g DW/m2 (Yaringa, 3.0 m) o At Yaringa there is a clear depth-related gradient in biomass o A depth related gradient in biomass is not seen when all sites are taken together • Whole macrophyte community biomass ranged between 75 g DW/m2 (Yaringa 6.2 m) and 202 g DW/m2 (Stony Pt, 1.2 m) o There is a clear depth related gradient in whole macrophyte community biomass across all sites • After Zostera, the next most abundant macrophytes were epiphytic macroalgae (seen at all sites), followed by Z. ovalis (seen at two sites) and Caulerpa cactoides (seen at Stony Point only) • Mature Zostera shoot numbers ranged between 533 per m2 (Yaringa, 6.2 m) and 1221 per m2 (Stony Point, 1.2 m). o There was a depth related gradient in shoot numbers at Yaringa sites, with more shoots at shallower sites o A depth related gradient in shoot number was not seen with all sites taken together • New shoots were seen at all sites, they were most abundant at Stony Point. • Rafting shoots were seen at all but the deeper of the two Yaringa sites • There was a strong tendency toawards shoots with multiple leaf clusters per shoot at shallower sites. • Median shoot lengths ranged between 322 mm (Stony Pt, 1.2 m) and 592 mm (Yaringa, 6.2 m) o There was a depth related gradient in shoot length with all sites taken together o Longer shoots, stems and leaves were seen in deeper water with less light o Interestingly such a gradient was not evident at Yaringa, with similar shoot lengths at 4.2 and 3 m. • Nodes per stem were similar across all sites o If growth rates can be assessed, these data can be used to determine shoot age • There was a depth related gradient in leaf length, across all sites and at the Yaringa sites o Longer leaves were seen at deeper sites with less light. • There was a depth related gradient in leaf width:thickness ratio across all sites and at the Yaringa sites o Leaves are wider and/or thinner at deeper sites with less light.

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 25

5 Discussion 5.1 Biomass The collection of Z. nigricaulis and associated macrophyte samples allows quantification of the biomass of the different macrophyte community components. The linear relationship between depth and biomass suggests there is likely to be a (logical) relationship between light availability and biomass. Biomass appears to be most strongly related to total leaf area. Continued documentation of biomass will allow seasonal variation in biomass to be determined, and in turn calculate approximate primary productivity.

5.2 Shoot density Shoot density was easily quantified from the collected samples. Shoot density showed a clear relationship to depth when Yaringa sites were viewed in isolation, but this trend was not apparent when data was viewed together. The addition of further sites to document conditions down the depth profile (as they are at Yaringa) at more locations will show whether shoot density is site specific and unrelated to depth, or location specific and related to depth.

Additionally, the number of ‘new’ shoots (those that had not developed lignified stems) could be quantified from samples. Rafting shoots were also identified and quantified in the samples. Over time, this data will provide a measure of rates of production of new shoots in the meadow and asexual reproduction respectively.

5.3 Shoot morphology Shoot length was also easily quantified from the collected samples. The positive relationship between shoot length and depth is consistent with a shoot length response to light availability (less light=longer shoots). The lack of such a pattern at Yaringa suggests other factors, perhaps current speeds, are important.

It will be prudent to assess the optimal number of shoots that need to be measured to provide accurate data. It may be possible to reduce the number of shoots measured, saving processing time.

The number of leaf clusters and number of leaves per shoot was easily quantified on a sub-sample of six shoots from each sample. The number of leaves per shoot showed a clear negative relationship to depth. This is consistent with the findings of Bulthuis (1983) that leaf number decreases as light availability decreases. Shoots with multiple leaf clusters were comparatively rare at all sites, though were far more common at shallower sites than deep. Again, this is consistent with the findings of Bulthuis (1983).

Nodes per stem were similar across all sites. If an assumption drawn from Bulthuis (1983), that leaf growth rate is not affected by light availability, is correct, shoot ages appear to be similar across all sites.

5.4 Leaf morphology Leaf length was also easily quantified from the collected samples (measured on a subsample of six shoots). Leaf length also showed a positive relationship to depth. This is consistent with the findings of Bulthuis (1983) that leaf length increases as light availability decreases.

Port of Hastings Subtidal Seagrass Monitoring Pilot Study 26

As with shoot length, it will be prudent to assess the optimal number of shoots/leaves that need to be measured to provide accurate data.

Leaf width and thickness did not show clear relationships to depth when viewed in isolation, but the ratio of leaf width to thickness did. Leaves appeared to become wider and/or thinner with depth. These data are interpreted with caution, in particular leaf thickness data. Leaf surfaces, particularly those from shallower sites, become covered by micro-epiphytes (microalgae mostly). This layer may confound measurement of leaf thickness – making leaves appear thicker than they actually are. While care was taken not to select heavily epiphytised leaves, cleaning epiphytes from leaves was deemed too time consuming. Epiphytes on the edges of leaves had a proportionately much smaller effect on leaf width measurements.

Previously, Bulthuis (1983) found that leaf width showed an inverse relationship to light availability (wider leaves are found at lower light availabilities).

Attachment 4

The APPEA Journal 2017, 57, 10–25 Peer reviewed paper http://dx.doi.org/10.1071/AJ16193

Five years on: monitoring of Long Island Point’s Western Port wastewater discharge

Melanie Bok A,C, Scott Chidgey B and Peter Crockett B

AEsso Australia Pty Ltd (Esso), 12 Riverside Quay, Southbank, Vic. 3006, Australia. BCEE Consultants, Unit 4, 150 Chesterville Road, Cheltenham, Vic. 3192, Australia. CCorresponding author. Email: [email protected]

Abstract. The Esso Long Island Point facility is situated on the edge of Western Port, an important Ramsar designated wetland for migratory birds in Victoria, Australia. The gas fractionation and crude oil storage facility has operated for over 40 years and has discharged treated wastewater to Western Port for most of these years in accordance with its environmental regulatory licence. The 2003 State Environment Protection Policy for Waters of Western Port is the Victorian Environment Protection Authority’s regulatory framework for licensing wastewater discharges to the wetland, and among other items, requires that discharges must cause no ‘detrimental change in the environmental quality of the receiving waters’ or ‘chronic impacts outside any declared mixing zone’. A major upgrade to the water treatment facility in 2010 included a risk-based marine ecosystem program to monitor key environmental indicators including water quality, jetty pile invertebrate communities and seagrass condition. The program’s longer-term monitoring record has allowed assessment of potential chronic effects on invertebrates and seagrass by comparing temporal changes at monitoring sites over the period from pre- operations (2010) to present (2016) and spatial changes between near-field to far-field sites, kilometres from the discharge point. The program has shown that management of the discharge maintains beneficial uses and environmental objectives at the boundary of the mixing zone, and the marine ecosystem is protected from potentially slower and longer-term adverse effects in the far-field. The program demonstrates that the treated wastewater discharge has had no adverse impact on key environmental indicators in Western Port over the longer-term study period.

Keywords: crude storage, environment, fractionation, marine monitoring, Ramsar, water treatment.

Accepted 20 February 2017, published online 29 May 2017

Introduction Environmental characteristics of Western Port The gas fractionation and crude oil storage facility at Long Island Western Port is an environmentally sensitive embayment that Point (LIP) plays a vital role in Bass Strait oil and gas production. comprises subtidal and intertidal seagrass beds, intertidal rock Situated near Hastings, 75 km south-east of Melbourne, the platforms, subtidal reefs, sandy beaches, intertidal mudflats, facility carries out the final stage in the processing of liquid tidal channels, saltmarshes and mangrove habitats. This habitat petroleum gas (LPG), and stores crude oil before distribution to supports a diverse range of fauna, including birds listed in the refineries and loading onto crude tankers for export. Japan–Australia Migratory Birds Agreement (JAMBA) and The facility manages wastewater that comprises small amounts the China–Australia Migratory Birds Agreement (CAMBA). of produced formation water from offshore platforms, as well as Western Port is listed as a Wetland of International Importance stormwater runoff from tank bunds, pads and wash-down bays for migratory birds under the Ramsar convention. Western at the facility. The water treatment unit (WTU) comprises three Port encloses two large islands, French Island and Phillip ponds to separate oils and to treat organic wastewater constituents: Island, along with several smaller islands and expansive an aerobic biological oxidation treatment pond, followed by a mudflats. In addition to being a commercial port, Western Port settling pond where solids coagulate and settle, and the final clean is popular for recreational boating, fishing, swimming, diving, holding pond (Fig. 1). Treated and tested effluent is pumped nature study and bird watching (Ministry of Conservation 1975; during southerly ebb tides from the final pond to the outfall Melbourne Water 2011). diffuser located at 7 m below the sea surface (8.6 m below mean The important marine habitats in Western Port are characterised sea level), under the loading jetty in Western Port (Fig. 2). by several key species. The white mangrove (Avicennia marina)

Journal compilation Ó APPEA 2017 CSIRO PUBLISHING www.publish.csiro.au/journals/appea Western Port wastewater monitoring: 5 years on The APPEA Journal 11

Crude tank farm

Refrigerated storage tanks LPG fractionation

Wastewater treatment unit

Jetty

Fig. 1. Aerial photograph of Long Island Point fractionation and crude storage plant.

Cargo wharf 2 km

Southward Crib Point ebb tide jetty current 5 km

Fig. 2. Long Island Point water treatment facility and jetty with diffuser. 12 The APPEA Journal M. Bok et al.

characterises the dense mangrove forest that lines ~40% of the fish. These encrusting invertebrates are colourful and diverse shoreline. Western Port also supports one of the most significant members of the Western Port ecosystem that inhabit the jetty stands of saltmarsh in south-eastern Australia, considered to piles immediately downstream and upstream of the facility outfall be of national significance (Department of Sustainability and and at two further jetties, a cargo wharf to the north and Crib Environment 2000). Seagrasses (Fig. 3)formextensive Point jetty to the south. Invertebrates include sponges, hydroids, intertidal and subtidal beds that provide habitat for a range of bryozoans and ascidians; all of which are filter feeders, which other marine plants, invertebrates and fish, which are a key factor capture and consume plankton and organic detritus from the in the Ramsar listing of Western Port. Seagrasses grow along surrounding water. The regular tidal currents in Western Port the intertidal mudflats of Western Port and along the shallow make it a favourable site for filter-feeding invertebrates. subtidal fringe of the channel inshore of the facility jetty. Two Most of Western Port is well flushed by tidal currents entering seagrass species, Zostera nigricaulis and Zostera muelleri, and exiting from Bass Strait through the western entrance. Prevailing dominate the vegetated areas of the lower intertidal mudflats winds produce a generally clockwise water circulation in the bay. and subtidal channels. Sites north of the facility jetty comprise Seawater quality in the North Arm of Western Port, where the monospecificstandsofZ. nigricaulis and associated algal facility is located, is affected by strong tidal mixing between the epiphytes (seaweeds attached to the seagrass leaves and stems). ocean waters of Bass Strait in the south and the enclosed bay area Seagrass beds south of the facility jetty include some Halophila to the north. Tidal currents carry ocean waters northward past australis, and from time to time, the rhizophytic (rooted) large LIP during flood (rising) tides and back from the north of green seaweed Caulerpa sp. (mostly C. cactoides). Western Port during ebb (falling) tides. Wind-generated waves Seagrasses provide both primary productivity, as well as re-suspend sediments over large expanses of intertidal mudflats habitat for a wide range of other plants, invertebrates and in the north and create highly turbid waters during periods of

(a) (b)

(c) (d)

Fig. 3. Examples of intertidal and subtidal seagrass in North Arm, Western Port: (a) intertidal Zostera seagrass near Long Island Point; (b) subtidal Zostera nigricaulis;(c) algal epiphytes blanketing subtidal Z. nigricaulis north of Long Island Point in June 2014; and (d) subtidal Z. nigricaulis with red algal epiphytes. Western Port wastewater monitoring: 5 years on The APPEA Journal 13

strong winds. Solar heating of the mudflats in summer, and detrimental change in the environmental quality of the receiving evaporative cooling in winter, also influence the temperature, waters, as determined by an in-stream monitoring and assessment salinity and density of the northern bay waters. program’. Salinity in the north of the bay is also influenced by freshwater runoff in the cooler months. The north of Western Port remains Nature of the discharge at lower salinity than ocean waters in winter because of the rainfall Water quality within the facility is managed, first, by separating as input, whereas evaporation in the north of the bay during summer much water from the crude as possible in processes upstream of can result in higher salinity than in ocean waters. These combined the WTU; second, by optimising the environment in the aerobic processes create gradients in water quality from north to south, biological-oxidation treatment pond for bacteria growth, so as at different times of the year. LIP is located at a central point along for the bacteria to metabolise organic material; and third, by these gradients, so that water quality at LIP changes naturally over reducing the carryover of biological material into the settling the tidal cycle, and over the seasons. Seawater quality in Western pond. Wastewater from the clean pond is pumped to a purpose- Port has been monitored monthly by the Victorian Environment designed, 21-m long diffuser located beneath the loading jetty. Protection Authority (EPA) at three sites since 1984 (Longmore Effluent is discharged only during ebb (outgoing southerly) tide 1997). The EPA monitoring site at Hastings is representative of currents and when effluent quality meets EPA licence conditions. ambient seawater close to the facility. The discharge is limited to a maximum of 1.4 million litres (1.4 ML) per day. Facility wastewater discharge regulations Both the crude oil volumes produced from the offshore oil fields, and the water inventory at the facility, have reduced since The facility’s environmental discharges are regulated by a licence 2010. Consequently, the volume of organic material requiring issued by the EPA under the Environment Protection Act (1970). treatment in the biological process installed at the WTU has Licence holders must comply with the requirements of the Act reduced and the total volume of water requiring discharge has and the State Environment Protection Policy 2003 (Waters also reduced since commencement of discharge in 2011. In the of Victoria), known as the SEPP. Licence conditions for the past 2 years, facility operations staff have prioritised a slow and water discharge include requirements for zero waste and floating steady discharge regime that maximises the effectiveness of the oil, and a range of specific limits for physical parameters biological-treatment process. The frequency of discharge events (maximum flow rate) and chemical parameters (biochemical is usually sporadic and intermittent, with less than one discharge oxygen demand, suspended solids, ammonia, total nitrogen, event per week, with daily flow on days of discharge in 2016 pH, BTEX, various metals, anionic surfactants, phenolic averaging ~800 thousand litres, or 0.8 ML (Fig. 4). Wastewater compounds and total sulfide). The licence also specifies a dilution through the diffuser is predicted to range from 60 : 1 to mixing zone for nitrogen and metals at specified distances 120 : 1 at the diffuser (initial dilution with currents of 0.1 m/s and from the discharge point (180 m and 100 m respectively). 0.4 m/s respectively) and from 180 : 1 to 250 : 1 at 100-m distance The SEPP states that EPA licence holders must also (0.1 m/s and 0.4 m/s currents; CEE 2010). ‘implement effective wastewater management practices that The WTU operation and effluent quality are closely monitored minimise environmental risks to beneficial uses’ (Environment by operations and laboratory staff to detect early warning signals Protection Authority 2003). Beneficial uses include primary- and and troubleshoot problems. The treatment plant capabilities secondary-contact recreation, aesthetic enjoyment, aquaculture and limits are well known to site staff, and, in planning for and consumption of fish, industrial and commercial use, modifications within the plant that would affect the water navigation and shipping, and aquatic ecosystems. The treatment system, they verify that water can be maintained discharged water must not result in ‘acute lethality at the point within regulatory limits. Laboratory samples are processed of discharge’ or cause ‘chronic impacts outside any declared weekly and anomalous results are quickly relayed to operations mixing zone’ and licensees must manage mixing zones to result supervisors for action. Site personnel verify that emergency in no ‘harm to humans’, ‘unacceptable impacts on plants and contingency options are available for further recycling and animals’,or‘loss of aesthetic enjoyment or an objectionable treatment within the plant before discharge if required. odour’. In addition, licensees ‘must develop an understanding of how [their] discharge will interact with the environment and how the receiving waters will be impacted’ (Environment Protection Monitoring program overview Authority 2015), which should include consideration of physical A risk-based marine-ecosystem program was established to (currents, depth profiles), chemical (background concentrations) confirm that licence requirements were met and to confirm that and biological attributes. the SEPP-listed beneficial uses of Western Port in the vicinity of In addition to the specific conditions of the site’s EPA licence, the facility remained protected from any potential effect of the licenced dischargers to Western Port must comply with all discharge. The program characterised spatial and time-based conditions of Schedule F8 to the SEPP (hereafter referred to as changes in key environmental indicators at the jetty diffuser, ‘the Schedule’; Environment Protection Authority 2003). The within the mixing zone, and at suitable locations beyond the Schedule lists a range of environmental-quality indicators and mixing zone, and assessed these characteristics for potential objectives that must be maintained to protect the defined changes as a result of the discharge. beneficial uses of Western Port, including several chemical The marine environmental monitoring program commenced and physical water-quality parameters. The Schedule requires in 2010, shortly before the WTU upgrade was commissioned and that discharges into Western Port must be shown to ‘cause no discharge from the outfall diffuser recommenced. The approach 14 The APPEA Journal M. Bok et al.

2000

1500 Pre-operational Operational period

1000

500 Wastewater discharge (kL/d) Wastewater

0 Apr-10 Oct-10 Apr-11 Oct-11 Apr-12 Oct-12 Apr-13 Oct-13 Apr-14 Oct-14 Apr-15 Oct-15 Apr-16 Oct-16 Jan-10 Jan-11 Jan-12 Jan-13 Jan-14 Jan-15 Jan-16 July-10 July-11 July-12 July-13 July-14 July-15 July-16

Wastewater treatment plant calendar day discharge (kL) Water quality monitoring

Seagrass monitoring Invertebrates monitoring

Fig. 4. Effluent discharges into Western Port and surveys undertaken as part of the marine-ecosystem monitoring program. to ecosystem monitoring was based on the understanding of Monitoring approach effluent dispersion from the outfall diffuser, concepts of effluent-exposure gradients along the dispersion pathways and Monitoring for these three environmental indicators over the the identification of key environmental indicators. 2010 pre-operations period through to 2016 provided a data The program monitors three key environmental indicators record capable of demonstrating potential broader spatial and fl identified as representative and important components of the longer-term effects. The history of ef uent discharges over the – Western Port ecosystem near the discharge, namely, water 2011 16 period, together with the water quality and ecological- quality, jetty pile invertebrate communities and seagrass monitoring events, are shown in Fig. 4. fi condition. These three components were chosen as sensitive, Surveys commenced before the rst discharge from the exposed and widely present indicators by which to measure upgraded WTU so that pre-operational environmental conditions potential changes to the environmental condition of Western were documented. The program began with two pre-operations Port, as a result of the facility’s wastewater discharge: surveys in late 2010 and early 2011. Then, three water quality monitoring events and four marine ecological-condition monitoring * Water quality was chosen as an indicator to show spatial or events occurred during the first 9 months of wastewater discharge temporal changes in nutrient and physical parameters along from the initial discharge in 2011. In addition to monitoring the dispersion pathway, as a result of the effluent discharge. The activities, ecotoxicity testing of wastewater and diffuser natural ambient water quality conditions were documented, modelling were undertaken in the early stages of the program. as well as water quality during periods of effluent discharge. Initial water quality, marine-ecosystem and laboratory- Water quality was sampled along the dispersion pathway, and ecotoxicity results from 2010 and 2011 showed that there was at upstream and remote downstream reference sites. no detrimental change in environmental quality in the vicinity * Invertebrates were chosen as an indicator because invertebrates of the facility as a result of the discharge over the first year live close to the effluent discharge and are the most likely after commencement of the discharge (CEE 2012, 2015). ecosystem component to be exposed to high concentrations This period of monitoring demonstrated the importance of of effluent when it is discharged, and, therefore, are most likely basing regulatory requirements on site-specific environmental to show effects along the dispersion pathway. Because they are characteristics and the need for sound science to underpin filter feeders, they are also an ideal indicator for the impacts of regulatory limits and industry practices when operating in wastewater constituents. sensitive environments (Hall and Chidgey 2013). The fi * Seagrasses were chosen as an indicator because they are both outcomes of the rst phase of the monitoring program important and ubiquitous, and they enable identification of informed the establishment of the current EPA licence limits long-term changes close to the facility relative to upstream and and the mixing zone extents for metals and nitrogen. remote downstream reference sites. The monitoring program continued in 2013/14, so as to document possible longer-term variations in natural ecological The rationale for assessment of effluent impacts on characteristics that might result in responses from ecosystem invertebrates and seagrass at LIP is based on the concept that communities to the effluent discharge at the jetty and within marine biota will show greatest response to effluent where their the mixing zone. The monitoring program in 2013/14 applied exposure is greatest, and the effect will reduce as the exposure to the same methods as developed in 2010/11 for water quality, effluent decreases. Steep gradients in effluent exposure occur invertebrate and seagrass monitoring and demonstrated that within close proximity to the outfall (that is, within the mixing beneficial uses and environmental objectives were protected at zone), as exposure decreases exponentially with distance. the boundary of the mixing zone (CEE 2016). Western Port wastewater monitoring: 5 years on The APPEA Journal 15

Efforts in the 2015/16 program turned to verifying that effluent plume in the water column and informed the depths for potential longer-term effects (chronic effects) from the discharge sampling nutrients (nitrogen and phosphorus). could be ascertained and any potential effects in the far-field Seawater samples for laboratory analysis were collected (beyond the mixing-zone boundary) as a result of the discharge in accordance with EPA Victoria guidelines (Environment could be separated from natural variation. Monitoring continues to Protection Authority 2009). Surface seawater samples (0.3-m provide evidence that the marine ecosystem beyond the mixing depth) were collected directly into 1-L (litre) sample bottles. zone is protected from acute effects of the discharge and remains Subsurface samples were collected at (nominally) 3-m, 5-m and protected from potential slower, chronic effects and from effects 7-m depths by using a 1.5-L weighted, narrow-mouthed, rigid as the natural ecosystem varies in character from year to year. sampling bottle. All water samples for nutrient analysis were collected into new 1-L polyethylene bottles, kept cool and in Methods darkness and delivered to NATA accredited laboratories. Samples were analysed for total ammonia (NH3), total Monitoring methods used were based on standard procedures nitrogen (TN) and total phosphorus (TP). for water quality sampling, sessile encrusting invertebrate Sites were located using GPS (accuracy Æ 4 m) and reference fi quanti cation using underwater photography and seagrass points (such as the outfall pipeline, jetty structure and mooring biomass measurement by random sampling. The methods were dolphins). adapted to suit the particular conditions of Western Port in the Sufficient time was allowed after the start of discharge vicinity of LIP and have been used since the establishment of pumping for the effluent to be dispersed by the tide, before pre-operational conditions in 2010. sampling. Current speeds downstream of the diffuser were measured using drogues, and the time interval required for Ambient water quality effluent dispersion to the sampling sites was calculated Prior to discharge, samples were collected 2000 m and 180 m accordingly. During the 2016 monitoring event, a total of north of the diffuser and 20 m, 200 m and 2000 m south of the ~1.1 million litres (1.1 ML) of effluent was pumped to the diffuser. Then, for sampling concurrently with the discharge, outfall over ~4.5 h, corresponding to an average flow rate of water quality sampling sites were positioned along the dispersion 75 L/s. pathway south of the diffuser to the boundary of the nitrogen For the 2016 monitoring event, 42 water samples were mixing zone at 180 m south (downstream) from the diffuser, and collected in total from 0.3-m to 7-m water depths, and 18 at reference sites 180 m upstream (north) and 2000 m downstream salinity, temperature and dissolved oxygen profiles were (south) (Fig. 5 and Table 1). All sites were aligned with the measured at upstream and downstream sites before and during prevailing north–south tidal current direction. discharge. Water samples for nutrient analyses were collected Profiles of conductivity (salinity), temperature and dissolved from the surface and at 3-m, 5-m and 7-m depths downstream of oxygen were measured between the seabed and surface during the the diffuser during discharge. Drogues were deployed at sites discharge, by using a calibrated multi-parameter Hydrolab sonde. 20 m south and 50 m south, to measure the tidal current passing Salinity measurements were used to identify the position of the the diffuser. Currents measured at 20 m south typically ranged

Table 1. Monitoring sites (distances are approximate)

Water quality Sessile invertebrates Seagrass 2000 m north Cargo wharf (2000 m north) 900 m north 180 m north Row 10 (40 m north) 200 m north Diffuser Row 8 (32 m north) 200 m south 20 m south Row 6 (24 m north) 1000 m south 50 m south Row 4 (16 m north) 100 m south Row 2 (8 m north) 180 m (during discharge) Row 1 (4 m north) 200 m south (before discharge) Diffuser 2000 m south Row 1 (4 m south) Row 2 (8 m south) Row 4 (16 m south) Row 6 (24 m south) Row 8 (32 m south) Row 10 (40 m south) Crib Point jetty (5000 m south) 16 The APPEA Journal M. Bok et al.

2 km north

180 m north

180 m radius mixing zone Diffuser for nitrogen 20 m south

50 m south

100 m south

180 m south

2 km south

Fig. 5. Water quality monitoring sites. between 0.23 and0.33 m/s ina southerly direction, with occasions for example, Butler and Connolly 1995). The sessile invertebrate of speeds less than 0.05 cm/s due to large scale eddies moving assemblage on jetty piles was recorded by scientist divers who around the jetty. Currents at 50 m south were ~0.12 m/s, which photographed the piles using 0.4-m by 0.3-m quadrats (0.12 m2). was likely to be due to eddies in the lee of the jetty. At each site, photo-quadrats were taken on at least six individual piles at 5-m and 7-m depths (chart datum), except at the diffuser, where the 7-m depth photo-quadrats were taken on the diffuser Jetty pile invertebrates itself. The depth at which divers collected photo-quadrats was Sessile invertebrate communities were monitored at the determined before each dive, on the basis of tide predictions and following three locations: the facility jetty at LIP, Crib Point local observations, so as to collect photo-quadrats at the correct jetty and the cargo wharf jetty (Fig. 6 and Table 1). Water quality depth relative to the diffuser/chart datum. At Crib Point and measurements during effluent discharge were used to determine the cargo wharf, photo-quadrats were recorded at 5-m and 7-m the depth of biological sampling sites on jetty piles, along the depths on piles towards the middle of each jetty (i.e. away from exposure pathway at each site. Sites along the exposure gradient the edges). beneath the facility jetty south of the diffuser represented those Photo-quadrats were assessed for the percentage cover of most likely to be affected by facility wastewater. These were sessile invertebrates by using point-intercept analysis. Fifty grouped into highest effluent-exposure sites, mid-range effluent- points were superimposed over each image, with two points exposure sites, low effluent-exposure sites and reference sites randomly positioned in each cell of a five-by-five grid. The (no direct effluent exposure). Sites under the facility jetty north of identity of the sessile invertebrate under each point was the diffuser were positioned symmetrically opposite the south recorded and used to calculate the percentage cover for different sites, to allow direct comparison with exposure sites. Sessile invertebrates in each image. The invertebrate fauna on the jetty invertebrate communities on jetty piles at Crib Point jetty (5000 m piles comprised the following four groups: sponges (phylum south) and the cargo wharf (2000 m north) at the same depths Porifera), hydroids (phylum Cnidaria), bryozoans (phylum as those at LIP represented far-field reference locations, which are Bryozoa) and ascidians (phylum Chordata; Fig. 7). Records most unlikely to be directly exposed to effluent. included individual species as well as general or morphological The methods used to monitor the jetty pile invertebrates are categories; all will be referred to as ‘species’ here. The mean and widely used and have been developed over several decades (see, standard error of each species was calculated for each site, depth Western Port wastewater monitoring: 5 years on The APPEA Journal 17

Jetty deck Jetty piles Potentially affected by effluent discharge Unlikely to be affected

5 m

7 m

Photoquadrats

Row 2 Row 1 Diffuser Row 1 Row 2 South (rows 1, 2, 4, 6, 8) North (rows 1, 2, 4, 6, 8)

Crib Point Long Island Cargo jetty Point jetty wharf

2 km

Fig. 6. Sites for sessile invertebrate monitoring, with inset of Long Island Point jetty piles. and survey. Data were plotted against distance downstream of Results the diffuser and analysed for patterns in the abundance of sessile invertebrates consistent with a response to effluent-exposure Ambient water quality gradient, either via a difference between exposed sites and A clear salinity gradient was present along the water quality reference sites, or differences along the effluent-exposure gradient. sampling sites, typical of expected seasonal weather conditions. The salinity and temperature profiles showed that there was negligible density stratification before, or during the discharge, Seagrass condition that might have trapped effluent in lower layers. The biomass of seagrass and algae was monitored at two sites Water quality profiles and nutrient samples showed that the near the facility jetty (200 m north and 200 m south of the effluent dispersed southward of the diffuser and diluted rapidly discharge) and two reference sites 900 m north and 1000 m as it rose and mixed with the strong tidal currents under the south of the discharge (Fig. 8 and Table 1). At each site in jetty, before reaching the open waters of Western Port, ~40 m each survey, divers collected 10 samples of seagrass for south of the diffuser. Water quality results showed that effluent biomass measurement. Samples of seagrass and macroalgae concentration reduces rapidly over thefirst 100 mfrom theoutfall, were collected from 0.25 m by 0.25 m quadrats (0.05 m2). with dispersion always strongest to the south of the diffuser, in Quadrats were placed haphazardly within seagrass at each site the direction of the current during discharge. During effluent and all excess seagrass and macroalgae material was carefully discharge events in all operational surveys, the diffuser at 7-m separated so that only seagrass rooted within the quadrat, and depth chart datum (8.5-m depth Australian Height Datum) algae attached to it, were collected. Similar methods were used produced an initial dilution at least 100 : 1 within 20 m of the by MSE (1989) in their 20-year monitoring program at the cargo diffuser, as predicted by diffuser modelling. Effluent dilutions wharf north of LIP. calculated from salinity measurements in the 2016 monitoring Material was transferred underwater into mesh bags and event were consistently greater than 250 : 1. The highly dilute then above water into plastic bags for storage. Samples were effluent field subsequently diluted further, and was fragmented by stored frozen until sorted in the laboratory. Samples were turbulence as it dispersed southward from the diffuser with the subsequently defrosted and separated into seagrass material ebb tide currents. (Zostera nigricaulis and Halophila australis) and macroalgae Salinity is an accurate tracer of dilution and dispersal (Caulerpa sp. and other macroalgae species). Seagrass and of low-salinity effluent because salinity is not subject to macroalgal biomass was dried to constant weight in a drying biological reactions and uptake (as nutrients are). Profiles from cabinet and the dry-weight of each sample recorded. the mixing zone showed a gradual rise in salinity as the ebb 18 The APPEA Journal M. Bok et al.

(a)(b)

(c) (d)

Fig. 7. Images of invertebrates on jetty piles in Western Port. Clockwise in each panel: (a) Ascidians: Stolonica australis, Didemnidae sp., Sycozoa sp., Aplidium sp.; (b) Bryozoans:Bugulaserrata, Celleporaria sp., Tryphyllozoonsp., Cabereasp. (c) Sponges:Aplysilla sp., Aplysillasp., cf. Echinoclathriasp., Hollopsamma sp.; and (d) Hydroids: Halopteris sp., Nemertesea sp., cf. Sertularia sp., cf. Sertularia sp. tide transported waters southward through the study area. The (200 m south) were similar to reference data (data collected discharge caused small reductions in salinity as the effluent before discharge began from all sites, sites upstream of the diluted and dispersed through the mixing zone downstream of discharge and sites more than 1000 m downstream of the the diffuser. The greatest reduction in salinity as a result of the discharge during discharge). discharge occurred at 20 m south of the diffuser, between 7-m and The total nitrogen concentration on the day of the discharge 5-m depths, which indicated the presence of the dispersing plume. event before the discharge commenced ranged from 0.17 mg/L Profiles recorded 50 m south of the diffuser during the discharge to 0.27 mg/L. The total nitrogen concentration in the dispersion did not show obvious reduction in salinity, which is consistent pathway during discharge ranged from 0.18 mg/L to 0.29 mg/ with the high initial and subsequent dilution the outfall diffuser L. Only samples at 20 m south (0.29 mg/L) and 50 m south achieves. In the 2016 monitoring event, the profile recorded (0.28 mg/L) exceeded reference concentrations during effluent 100 m south of the diffuser during discharge showed salinity discharge. These results demonstrated the high level of dilution in the upper 7 m of the water column was within 0.1 ppt of achieved by the diffuser resulting in nitrogen concentrations that reference sites, confirming the high dilution expected at this are close to ambient levels within the 180-m mixing zone for distance. Profiles recorded 20 m outside the mixing zone nitrogen. Western Port wastewater monitoring: 5 years on The APPEA Journal 19

1000 m south

200 m 200 m 900 m south north north

500 m

Fig. 8. Seagrass monitoring sites either side of Long Island Point jetty.

Total phosphorus concentration in effluent was 0.05 mg/L. most recent 10 years of EPA data for the Hastings site show The total phosphorus concentration in all ambient samples that median DIN concentrations were above the annual median (including reference sites) was 0.01 mg/L, indicating dilution objective. Background data collected by this monitoring program of total phosphorus in effluent to concentrations indistinguishable were slightly lower than the EPA data for the Hastings site from reference sites. but show a similar 20th to 80th percentile range. Median Variations in dissolved oxygen were negligible in the context DIN concentrations in samples taken adjacent to the diffuser of expected natural large-scale and measured longer-term during discharge were higher than the EPA Hastings data and variations. All recorded dissolved oxygen concentrations were reference site data, but well below the 75th percentile objective. above the SEPP objective of 90% saturation. DIN concentrations at the south edge of the 180-m mixing Long-term water quality monitoring data also indicated that zone were close to those seen at the EPA Hastings site, and the discharge has minor impacts on water quality in Western Port. well within the 20th to 80th percentile range seen in EPA data Average salinity of the facility effluent collected during early and reference site data. ecotoxicity assessments (2011–2012) showed that the effluent The water quality data collected during the monitoring had a salinity of ~10 parts per thousand (ppt, range 3–15 ppt), less program showed natural temporal and spatial variations in water than one-third the salinity of seawater (35–36 ppt). Salt in the quality in the vicinity of LIP, relating to seasonal, rainfall and effluent is attributed to the produced formation water. Figure 9 tidal movements. Temperatures have shown consistent seasonal shows the 10-year median salinity for the EPA Victoria patterns (summer warming, winter cooling); salinity reflects monitoring site at Hastings, median reference salinity rainfall in the catchment and tidal movements transport Western measured by this program (2010–16, n = 7) and the minimum Port waters north and south past the LIP. The area north of salinity recorded above the diffuser (2011–16, n = 4) and at the the LIP generally has more variable salinity and temperature downstream (south) edge of the mixing zone (n = 4). The because of its shallow depth and catchment inputs, while waters minimum salinity at the diffuser and at the south edge of the south of LIP more closely reflect the less variable water quality 180-m mixing zone during discharge cycles was similar to that of the open coast (Bass Strait). Data from the 10 surveys show in reference site data from this monitoring program. Minimum median reference concentrations of 0.20 mg/L total nitrogen (TN), salinities were lower than the 10-year median salinity at the EPA 0.002 mg/L total ammonia (NH3) and 0.01 mg/L total phosphorus Victoria Hastings site, but within the 10-year 20th percentile for (TP). These data are consistent with long-term (1984–13) trends this site. for Hastings (~2000 m south of the facility jetty) where median Median concentrations of dissolved inorganic nitrogen (DIN; values of nutrients are 0.17 mg/L TN, 0.007 mg/L NH3 and nitrate, nitrite and ammonia) are also shown in Fig. 9. The SEPP 0.013 mg/L TP. Schedule F8 objective for DIN in North Arm is an annual median The effect of the effluent discharge on ambient conditions of below 0.007 mg/L and 75th percentile below 0.015 mg/L. The was shown to be an intermittent, temporary and small increase 20 The APPEA Journal M. Bok et al.

in some nutrient parameters above ambient levels within 180 m 10 species each accounted for between 1% and 6% cover. There downstream of the diffuser. There are similarly intermittent, was no persistent change or trend in average species richness temporary and small decreases in salinity. Detectable effects per quadrat over the monitoring period, nor were there any on water quality are limited to the short period of the persistent differences in species richness among sites. The discharge event and a following period of less than 30 min as number of species per quadrat on the diffuser itself was slightly the effluent field is flushed and further diluted by tidal currents. lower than most other sites on four occasions, although still Overall, the effect of the effluent on water quality in the LIP well within the range seen across the area and monitoring region of Western Port was assessed to be small and intermittent period. Otherwise, there were no persistent differences in the and to result in temporary variation in water quality during the number of species at sites with high effluent exposure compared time of discharge in the range of annual natural variation. Water with those with low or no effluent exposure. Natural changes have quality at the boundary of the 180-m mixing zone and to within occurred in the abundance of key species and groups over the 1000 m downstream of the facility outfall remains within the period of monitoring, with quite large changes in the cover of key range of natural variation. invertebrate groupsat individual sites from survey to survey. These natural changes provide context for the assessment of potential Jetty pile invertebrates effects downstream of the facility wastewater discharge. Such 2 variation appears to be typical of sessile communities on jetty The number of invertebrate species in each 0.12-m quadrat piles (Kay and Butler 1983; Butler and Connolly 1999, 1995). – averaged about eight (range 4 10; Fig. 10). The following 6 The percentage cover of each major group of invertebrates fi of the 16 common invertebrate species identi ed from showed quite large variation over time (Fig. 11), as follows: photoquadrats accounted for 60–80% of invertebrate cover: Stolonica australis (semi-colonial ascidian), Didemnidae * Ascidian cover has varied between 30% and 70% cover from (colonial ascidian), Bugula dentata (arborescent bryozoan), survey to survey, with no persistent changes or trends. Changes Cabarea sp. (arborescent bryozoan) and Holopsamma sp. in ascidian cover from survey to survey have been generally (sponge) and ‘hydroid’ (general). Each of these six invertebrate consistent across all the monitoring sites. There is no obvious species accounted for between 9% and 19% cover. The remaining difference in ascidian cover between reference sites and

(a)(b) 37.5 0.016 37.0 0.014 0.012 36.5 0.010 36.0 0.008 35.5 0.006 35.0 Salinity (ppt) 0.004

34.5 Median DIN (mg/L) 0.002 34.0 0.000 EPA Vic LIP reference Diffuser South edge EPA Vic LIP Diffuser South edge Hastings median minimum MZ minimum Hastings Background median MZ median median (2010–16) (2011–16) (2011–16) median median (2011–16) (2011–16) (2004–13) (2004–13) (2010–16)

Fig. 9. (a) Salinity and (b) dissolved inorganic nitrogen values for Hastings (EPA Victoria), Long Island Point reference sites, diffuser and south edge of the mixing zone. Error bars indicate 20th and 80th percentiles.

12 Bluescope Farfield (North) 10 Midfield (North)

8 Nearfield (North) Diffuser (5 m) 6 Diffuser (7 m) Nearfield (South) 4

Species/Categories Midfield (South) 2 Farfield (South) Crib Point 0 Sep-2010 Feb-2011 Apr-2011 Jun-2011 Oct-2011 Dec-2011 Nov-2013 Feb-2014 Jun-2014 Nov-2014 Dec-2015 Pre-operational Operational

Fig. 10. Mean invertebrate species richness across survey areas over time. Western Port wastewater monitoring: 5 years on The APPEA Journal 21

80 Ascidians 70

60

50

40

30

20

10

0

60 Bryozoans

50

40

30

20

10

0 45 Sponges 40 Per Cent Cover Cent Per 35 30 25 20 15 10 5 0 60 Hydroids

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0 Sep-2010 Feb-2011 Apr-2011 Jun-2011 Oct-2011 Dec-2011 Nov-2013 Feb-2014 Jun-2014 Nov-2014 Dec-2015 Pre-operational Operational

Bluescope Farfield (North) Midfield (North) Nearfield (North) Diffuser (5 m)

Diffuser (7 m) Nearfield (South) Midfield (South) Farfield (South) Crib Point

Fig. 11. Abundance (percentage cover) of major invertebrate phyla across survey areas over time: 5-m depth (all sites) and 7-m depth (diffuser). 22 The APPEA Journal M. Bok et al.

those exposed to effluent. The cover of ascidians at sites on the mostly within the range of cover seen at other sites. The diffuser (at 7-m depth) and adjacent to the diffuser (at 5-m most recent survey in 2016 showed that hydroid cover on depth) has been similar to other sites in most surveys. Ascidian the diffuser was the same as that seen at the north reference cover was on average lower at the diffuser (at 5-m depth), site (the cargo wharf). and substantially lower on one occasion (November 2013). * The complementary shift in sponge and hydroid abundance Ascidian cover has been, on average, lower at the diffuser occurred across all the sites (including reference sites), so is (at 7-m depth) and substantially lower on two occasions (June most likely to represent a shift in environmental conditions, 2014 and November 2014). In each case, where ascidian cover such as potentially being due to changes in rainfall patterns was substantially lower, it increased to be similar to more during and after the Millennium Drought (2003–10) in south- distant and reference sites in subsequent surveys. eastern Australia (Bureau of Meteorology 2016). * Bryozoan cover has varied between 10% and 35% cover Photographs (Fig. 12) show the profusion of invertebrate from survey to survey, with no persistent changes or trends. species encrusting the diffuser pipe and growing to the edges Changes in bryozoan cover from survey to survey have been of the ports. Invertebrates adjacent to the ports are occasionally generally consistent across all the monitoring sites. Lower cleared around the ports by the turbulence of effluent discharge bryozoan cover was generally found on the diffuser (at 7-m (e.g. June 2011, November 2013), but quickly regrow over depth) than other sites, a pattern that has been apparent in both the disturbed area. The invertebrate community can be seen to the pre-operational and operational periods. It is thought the change in composition over the monitoring period, but remains horizontal orientation of the diffuser structure (versus vertical abundant and rich and comprises the same groups of invertebrate piles) may affect the bryozoan cover at this site. fauna. The photos of the diffuser demonstrate a constant turnover * The cover of sponges has varied between 10% and 35% from in community populations and resilience to the temporary survey to survey. Sponge cover was low throughout 2011 influences and perturbations of effluent discharge. and has been higher since November 2013. Changes in Overall, the data at three main sites within 7 km of the sponge cover from survey to survey have been generally discharge show that while the proportion of cover attributed to consistent across all the monitoring sites. There are no each species varies from survey to survey, the composition of the persistent differences in the cover of sponges between the community is stable and is dominated by the same five or six sites with highest effluent exposure and sites further away or species in each survey. There were no temporal or spatial trends reference sites. for more or less species per quadrat at sites exposed to effluent, * Changes in the cover of hydroids over the monitoring period except on several occasions where species richness was lower on were approximately the inverse of changes seen in sponge the diffuser structure itself. There were no spatial or temporal cover, that is, hydroid cover was highest in 2011, and lower gradients in the abundance of ascidians, bryozoans or sponges from 2013 to 2015. Changes in hydroid cover from survey to that were consistent with an influence of the effluent discharge, survey have been generally consistent across all monitoring except on and immediately adjacent to the diffuser. sites including reference sites. Hydroids have shown the greatest range in cover, from less than 10% up to 40% in some surveys. Hydroids have, on average, been more Seagrass condition abundant on the diffuser (at 7-m depth) than other sites The seagrass beds at themonitoring sites comprise mostly Zostera during the operational period, but values have been still nigricaulis, with epiphytic macroalgae, Halophila australis

Sep-2010 Apr-2011 Jun-2011 Dec-2011

Nov-2013 Feb-2014 Jun-2014 Dec-2015

Fig. 12. Time sequence of biota around a single diffuser port (7-m depth). Western Port wastewater monitoring: 5 years on The APPEA Journal 23

600

) 500 2

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200 Zosteranigricaulis biomass (g/m Zosteranigricaulis 100

0 Sep-10 Feb-11 Apr-11 Jul-11 Oct-11 Dec-11 Nov-13 Feb-14 Jun-14 Nov-14 Dec-15 Pre-operational Operational 900 m North 200 m North 200 m South 1000 m South

Fig. 13. Biomass of Zostera nigricaulis seagrass.

(seagrass) and Caulerpa cactoides comprising the remainder of to those found by other monitoring programs and research in the macrophytes at the monitoring sites. Western Port (Bulthuis and Woelkerling 1983; MSE 1989) and Zostera nigricaulis biomass was relatively stable over the Port Phillip Bay (Jenkins and Keough 2015). monitoring period and ranged from 150 g/m2 to 200 g/m2. Differences in seagrass biomass between sites was greatest in Conclusions the September 2010, November 2013 and December 2015 surveys, which all occurred in spring and showed the highest This paper presents the practices of managing and monitoring Zostera biomass (Fig. 13). wastewater discharges in a sensitive environment and the Seagrass biomass at the northern sites was higher and more outcomes of a long-term study focussed on measuring impacts variable than at the southern sites through the whole period. The in the receiving environment. large increase in Zostera nigricaulis biomass at 200 m north in The marine-ecosystem monitoring program has documented November 2013 is likely to represent a period of particularly the nature of key environmental indicators and values in the vigorous spring seagrass growth at this site. Biomass at this vicinity of the facility discharge at the loading jetty. The sites site has since returned to levels comparable to other sites. This and indicators were chosen in a robust and scientific manner, site was covered by a mat of fine macroalgae during the June based on the risk of the effluent discharge to the environment, so 2014 survey when Z. nigricaulis biomass was low. Stems of as to clearly demonstrate potential impacts from the wastewater Z. nigricaulis were observed persisting beneath the algal layer. discharge as it mixes in Western Port. Positioning monitoring Patterns at this site illustrate a wide variation in seagrass/ sites at the outfall as well as at reference sites, kilometres from macrophyte biomass in an area with no effluent exposure. the discharge point, meant the program was able to document Macroalgae at most sites were delicate species that were potential effects on a broad scale both upstream and downstream epiphytic on the seagrass (growing on the seagrass stems and of the discharge. The longer-term time-series of monitoring leaves). The large rhizophytic (rooted) macroalga, Caulerpa data was essential to identifying variations near the outfall in cactoides, is sometimes present at 200 m south and 1000 m the context of the natural environment. south and when present can account for a substantial proportion The study also showed that industrial discharges can co-exist of macrophyte biomass. The abundance of the smaller epiphytes in sensitive environments, provided that discharges are properly varied markedly, with generally higher abundance in spring– managed and the outfall is designed to minimise the concentration summer when nutrient and light availability is highest, and of wastewater constituents from which the ecosystem is exposed. lowest abundance in most cases in winter. The careful management of wastewater input flows and quality Seagrass was consistently present at all sites both north and within the site boundary before discharge, including maintaining south from the jetty. The temporal patterns in the abundance operator responsiveness and coordination between laboratory and of seagrass and macroalgae were generally similar to the north operations personnel are fundamental to maintaining compliance and south of the jetty. This pattern indicated that seagrass of the discharge stream with the site licence. habitats have not been adversely affected by the effluent The program has shown that as well as protecting beneficial discharge from the facility. The seagrasses and macroalgae uses and environmental objectives at the boundary of the mixing around LIP show seasonal and inter-annual variations similar zone, management of the discharge also protects seagrass and 24 The APPEA Journal M. Bok et al.

marine invertebrate populations from impacts beyond the mixing Butler, A. J., and Connolly, R. M. (1999). Assemblages of sessile marine zone. The program demonstrated that Western Port ecosystems invertebrates: still changing after all these years? Marine Ecology experience significant natural long- and short-term variability. Progress Series 182, 109–118. doi:10.3354/meps182109 CEE (2010). Report on dilution predictions for treated effluent discharge at Monitoring of environmental indicators for these ecosystems ’ over the 6-year monitoring period has shown that the treated Esso s Long Island Point Jetty. Consulting Environmental Engineers report to Esso Australia, December 2010. wastewater discharge has had no adverse impact on Western Port. CEE (2012). Long Island Point wastewater discharge marine ecological and Other industrial dischargers could leverage similar risk-based, water quality monitoring 2010–2011. CEE Consultants report to Esso long-term monitoring designs to understand the influence and Australia, May 2012. extent of industrial water discharges to the environment. CEE (2015). Long Island Point wastewater discharge effluent ecotoxicity The program will continue in future years to document monitoring. CEE Consultants report to Esso Australia, May 2014. relevant environmental conditions at appropriate temporal and CEE (2016). Long Island Point wastewater discharge marine ecological and spatial scales within the mixing zone and further afield, and water quality monitoring 2010–2016. CEE Consultants report to Esso continue to manage its wastewater discharge effectively so as to Australia, February 2016. protect the world-class marine environmental values of Western Department of Sustainability and Environment (2000). Mangroves and salt Port. marshes in Westernport Bay, Victoria, Ross, R. Arthur Rylah Institute, June 2000. Available at http://www.depi.vic.gov.au/__data/assets/pdf_ file/0010/226297/Mangroves.pdf [Verified 28 February 2017] Environment Protection Authority (2003). ‘State Environment Protection Conflicts of interest Policy (Waters of Victoria), No. S 107, Wednesday 4 June 2003.’ Victorian Government Gazette. (Victorian Government Printer: None. Melbourne) Environment Protection Authority (2009). ‘Industrial Waste Resource Guidelines: Sampling and Analysis of Waters, Wastewaters, Soils and Acknowledgements Wastes. Publication IWRG701.’ (EPA Victoria: Melbourne.) ‘ Esso Australia Pty Ltd is a wholly owned subsidiary of Esso Australia Environment Protection Authority (2015). Guidelines for Licence ’ Resources Pty Ltd. Both Esso and its joint venture partner for the LIP Management. Publication 1322.6, May 2015. (Environment Protection facility, BHP Billiton Petroleum (Bass Strait) Pty Ltd (BHPB), are thanked Authority Victoria: Melbourne.) for encouraging and authorising the publication of this paper. The ongoing Hall, K., and Chidgey, S. (2013). Assessing the environmental impact of protection of the environment in day-to-day plant operations would not water discharge in a sensitive near-shore marine environment. The APPEA – have been possible without the tireless work of facility managers and Journal 53, 301 312. superintendents. Jenkins, G., and Keough, M. (2015). Seagrass resilience in Port Phillip Bay. Final report to the Seagrass and Reefs Program for Port Phillip Bay. University of Melbourne report to DELWP. ‘ ’ References Kay, A.M., and Butler, A.J. (1983). Stability of the fouling communities on the pilings of two piers in South Australia. Oecologica 56(1), 70–78. Bureau of Meteorology (2016). Climate summaries archive: Victoria in 2010, doi:10.1007/BF00378219 2011,2013, 2014and2015.Available at http://www.bom.gov.au/climate/ Longmore, A. (1997). Analysis of water quality in Western Port, 1973–97 in current/statement_archives.shtml?region=vic&period=annual [Verified relation to protection of beneficial uses. Internal report no. 4. Marine 1 December 2016]. Freshwater Research Institute, Victoria, Melbourne. Bulthuis, D. A., and Woelkerling, W. J. (1983). Seasonal variation in standing Melbourne Water (2011). ‘Understanding the Western Port environment: crop, density and leaf growth rate of the seagrass Heterozostera a Summary of Current Knowledge and Priorities for Future Research.’ tasmanica, in Western Port and Port Phillip Bay, Victoria, Australia. (Melbourne Water: Melbourne.) Aquatic Botany 16, 111–136. doi:10.1016/0304-3770(83)90088-8 Ministry of Conservation (1975). ‘Western Port Bay Environmental Study.’ Butler, A. J., and Connolly, R. M. (1995). Development and long term (Ministry of Conservation, Victoria: Melbourne.) dynamics of a fouling assemblage of sessile marine invertebrates. MSE (1989). History and review of marine environmental monitoring in Biofouling 9(3), 187–209. Western Port, 1972 to 1989. Marine science and ecology report to BHPB. Western Port wastewater monitoring: 5 years on The APPEA Journal 25

The authors

Melanie Bok graduated as a Mechanical Engineer andrecently completed aMaster ofSustainability degree at Monash University. As the Environment and Regulatory Advisor at Esso Australia Pty Ltd, she gives advice on environmental and regulatory matters for Esso’s offshore platforms in Gippsland as well as the Long Island Point facility. This includes writing regulatory approval documents, coordinating monitoring programs for discharges, interfacing with environmental regulators and performing environmental roles in Esso’s emergency response team. She enjoys the Australian bush, cycling, kayaking, travelling, growing a vegie patch, and anything musical.

Scott Chidgey holds a Master of Science from the University of Melbourne, and is Principal Marine Environmental Scientist and Director of Consulting Environmental Engineers in Melbourne. Scott has more than 30 years of consulting experience in applied multidisciplinary marine studies throughout Australia, including oil and gas projects in Bass Strait, the Timor Sea and Gulf of Papua. He works closely with engineers and other scientists from a range of organisations, and maintains close contacts with research colleagues. Scott has particular expertise in developing and interpreting risk-based, integrated marine scientific programs for regulatory approvals and compliance purposes. He is responsible for risk- based monitoring programs for more than twenty licenced wastewater discharges in Australian states. Member of Australian Water Association and Australian Marine Sciences Association.

Peter F. Crockett is a senior marine scientist at Consulting Environmental Engineers. Peter has a Bachelor of Science (Marine Botany), Bachelor of Arts (Indonesian) and Master of Philosophy (Marine Botany) from the University of Melbourne. Peter is a member of the Institute for Marine Engineering, Science and Technology and the Australian Marine Sciences Association.

www.publish.csiro.au/journals/aj

Attachment 5

Report to: Jacobs Group (Australia) Pty Ltd

AGL Gas Import Jetty Project Crib Point, Western Port

Plume Modelling of Discharge from LNG Facility

FINAL

30 August 2018 AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility

AGL Gas Import Jetty Project Crib Point, Western Port

Plume Modelling of Discharge from LNG Facility

Contents

Executive Summary ...... 1 1. Introduction ...... 3 2. Purpose of this Report ...... 3 3. Basis for Design of Seawater Discharge ...... 4 4. Angle of Discharge from Port ...... 6 5. Effect of Water Depth on Dilution ...... 8 6. Effect of Discharge Rate on Dilution ...... 9 7. Effect of Number of Ports on Dilution ...... 11 8. What Dilution is Required? ...... 13 9. Bathymetry at Crib Point ...... 14 10. Currents at Crib Point ...... 15 11. Depth of Cold Water Layer ...... 16 12. Calculated Dynamic Richardson Number ...... 18 13. Dynamic Behaviour of Diluted Cold-Water Field ...... 20 14. Velocity and Translation of Plumes ...... 21 15. Conclusion ...... 23 References ...... 24 Appendix A: Near-field Modelling Parameters ...... 26 AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility

Report to Report prepared by Jacobs Group Ian Wallis (Australia) Pty Ltd CEE Pty Ltd Unit 4, 150 Chesterville Rd Cheltenham, VIC, 3192 Ph. 03 9553 4787

Document History

Document Details Job Name AGL Gas Import Jetty Project Job No. IS210700 Document Plume Modelling of Discharge from LNG Facility

Revision History Revision Date Prepared Checked Approved By By by Final (Ver 01) 19/07/18 I.Wallis S.Ada S.Ada Final (Ver 02) 30/08/18 I.Wallis S.Chidgey S.Ada AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 1

Plume Modelling of Discharge from LNG Facility EXECUTIVE SUMMARY

AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility using a Floating Storage and Regasification Unit (FSRU) to be located at the existing Crib Point Jetty on Victoria’s Mornington Peninsula. The project known as the “AGL Gas Import Jetty Project” (the Project), comprises: · Continuous mooring of a FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300 m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

The Crib Point Jetty in Western Port has been selected by AGL as the preferred location for the Project as it is an established, operating port. The proposal involves a continuously moored FSRU – essentially an LNG ship with equipment on board that circulates seawater to warm and regasify LNG. Gas from the FSRU will flow to the shore via the gas flowline.

During the heat-exchange process to warm LNG, up to 450,000 kL/d of seawater will be taken from Western Port by the FSRU, passed through a heat exchanger and discharged back to Western Port. The circulated seawater discharged from the heat exchanger will be approximately 7°C cooler than ambient seawater.

This report examines the dilution of the discharge of cooler seawater from the re- gasification facility. Several options to discharge the cooler seawater are considered. This information was prepared as an input to reports evaluating the ecological effects of the Project to be used in support of: · Referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act); · Referral under the Victorian Environment Effects Act 1978; and · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988.

The assessment concludes that discharged seawater would dilute rapidly after discharge, with the initial dilution at the seabed depending on the depth and number of discharge ports and the velocity of discharge.

AGL’s preferred design is a 6-port discharge. With discharge from six ports, (one on each side of the FSRU for each of the three regasification trains), the modelling shows that the discharged plumes will sink to the seabed within the berth area and produce a diluted field on the seabed that would be 0.3°C cooler than ambient seawater. This field will mix fully with tidal currents. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 2

When an LNG vessel is moored beside the FSRU, it may restrict the path of the plumes on the starboard side of the FSRU and the dilution could be temporarily reduced. This could occur about once a week over a 24-hour period.

During the period of weaker currents near slack water, the diluted field could form a stable layer on the seabed about 2 m thick, extending for a maximum of 200 m distance. The layer formed at slack water will become mixed into the ambient seawater when currents increase an hour later in the tide cycle.

In summary, the preferred 6-port design will always achieve the dilution required to mix the diluted cold-water field into ambient seawater in the passing tidal flow at Crib Point. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 3

1. INTRODUCTION

Jacobs Group (Australia) Pty Ltd (Jacobs) was engaged by AGL Wholesale Gas Limited (AGL) to undertake planning and environmental assessments for the AGL Gas Import Jetty Project. Jacobs engaged CEE Environmental Engineers (CEE) to define the marine environmental characteristics and identify key potential risks to the marine environment from the development and operation of the Project.

CEE has prepared this report to assess the discharge arrangements for seawater used in the heat exchanger that could be part of the proposed LNG Floating Storage and Regasification Unit (FSRU) while moored in Western Port at the Crib Point Jetty. Western Port has a surface area of 680 km2 at high tide but only 410 km2 at low tide, when 40 per cent of the surface is intertidal mudflats. Water movement is principally driven by the tides, although winds of more than 35 km/hr can also affect circulation (Hinwood and Jones, 1979). Most water enters and leaves Western Port through the western entrance, and there is a net clockwise circulation around French Island (Lee, 2000).

This report examines the local effects of the discharge of colder seawater from a potential regasification facility moored at Crib Point Jetty including the dilution of the discharge plume for various discharge options, as an input to the ecological assessment of the effects of this discharge.

2. PURPOSE OF THIS REPORT

The purpose of this report is to: · Predict the dilution of the discharged plume or plumes for single port, 2-port, 4- port and 6-port discharge options; and · Assess the extent of the diluted field of cooler seawater formed at slack water.

This information is prepared as an input to assessments of the ecological effects the Project on the marine environment to be used in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act); · A referral under the Victorian Environment Effects Act 1978; and · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 4

3. BASIS FOR DESIGN OF SEAWATER DISCHARGE

AGL provided a table of design parameters as the basis for design of the seawater discharge arrangements (see Appendix A). The key parameters are as follows: · FSRU vessel is moored continuously at Crib Point Jetty; · FSRU vessel is approximately 294 m long and 45 m across; · Depth of vessel is 11.6 m fully loaded and 9.3 m when empty; · Seawater discharge rate is 450,000 kL/d at full production; · Discharge rates of 300,000 kL/d and 150,000 kL/d also were considered.

Several discharge options were assessed based on old and new FSRU designs, including a single port of 1.1 m diameter on the starboard side; dual ports of 0.9 m diameter (one on each side); four ports of 0.5 m diameter (two on each side); and six ports of 0.45 m diameter (two on each side for each of the three regasification units on the FSRU). From the assessment of these options, the 6-port option was selected by AGL as the preferred discharge configuration.

Figure 1. Discharge Port Located Below Sea Level

The discharged plumes of cooler seawater are more dense that the adjacent seawater and therefore descend to the seabed. The shear between the descending plume and the ambient seawater causes mixing and dilution. The dilution of a descending plume increases with the depth of water from the discharge port to the seabed. There are three factors that influence the depth of discharge water below the port to the seabed: 1 The discharge port (or ports) must be located below sea level so that the discharge does not form a visible "waterfall”. Thus the discharge port (or ports) are located a nominal two times the port diameter below sea level. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 5

2 As shown in Figure 1, the vessel floats up and down with the tide, but the discharge ports remain the same distance below the water surface at low tide and high tide, so the depth of water below the ports is greater at high tide. 3 A fully loaded vessel has a draft of 11.6 m while an empty vessel has a draft of 9.3 m (2.3 m less depth into the water). Thus, as illustrated in Figure 2, the ports will be deeper below the water surface for a full vessel than for an empty vessel.

Figure 2. Depth of Discharge Port Varies with Vessel Loading

Table 1 summarises the calculations for the depth between the discharge port or ports and the seabed for the various conditions. As would be expected, the minimum water depth of 8.6 m occurs with a single port in a fully laden vessel at low tide, whereas the greatest water depth of 15.5 m occurs with 6-ports on an almost-empty vessel at high tide. There is large range in water depth for the discharge ports and the implications on initial dilution are assessed below.

Table 1. Depth of Water Below Discharge Ports for LNG Vessel

Parameter One port of Two ports of Four or Six Ports 1.1 m diam 0.9 m diam Water above port 2.2 m 1.8 m 1.0 m Diameter of port 1.1 m 0.9 m 0.5 m Tide Low High Low High Low High Empty vessel 10.9 m 13.9 m 11.5 m 14.5 m 12.5 m 15.5 m Full vessel 8.6 m 11.6 m 9.2 m 12.2 m 10.2 m 13.2 m AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 6

4. ANGLE OF DISCHARGE FROM PORT

The dilution depends on the length of the discharge plumes before they reach the seabed, which depends on the depth of water and the angle of discharge. The design data provided by AGL (see Appendix A) indicated that with 1 or 2 ports the discharge would be at 15 degrees below the horizontal. Thus, initial dilution simulations explored the effect of the discharge angle on initial dilution. These simulations were made for discharge from a fully laden vessel at low tide. This case has the smallest depth of water below the port (“worst-case”). Five discharge angles were examined: horizontal, 15 degrees below horizontal; 30 degrees below horizontal; 45 degrees below horizontal and vertical.

Initial dilution was calculated using the CEE computer model INITDIL. This model has been published in peer reviewed publication in the open literature (Wallis, 1985), verified against the performance of existing outfalls around the world (Wallis, 1981; Wallis 2016) and found to successfully predict the initial dilution of actual outfalls. The model calculated the initial dilution of buoyant and dense plumes, and estimates the thickness of the diluted cold-water field. The initial dilution can be predicted for the case of slack water (worst case) and for various current speeds.

Figure 3 shows the predicted initial dilution for the case of discharge from six ports of 0.45 m diameter with a total discharge of 450,000 kL/d from a fully loaded vessel at low tide. With horizontal discharge, the dilution is predicted to be 20:1. For comparison, an alternative plume model published by Cederwall (1968) predicts a similar initial dilution of 21:1.

Figure 3. Effect of Discharge Angle on Initial Dilution

25 Effect of Discharge Angle on Six-port Dilution

20

15

10 Predicted Initial Dilution

5

0 Horizontal 15 deg 30 deg 45 deg Vertical Angle of Discharge Port below Horizontal As can be seen in Figure 3, the dilution decreases from 20:1 with horizontal discharge to 12:1 at a discharge angle of 15 degrees and to 6:1 with discharge vertically downwards. The discharge decreases as the port angle declines below AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 7 horizontal (tilted down) because the length of the plume between the port and the seabed shortens as the downward angle increases, so there is less interfacial mixing and thus lower dilution. The conclusion drawn from these predictions is that the ports should discharge horizontally to maximise dilution. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 8

5. EFFECT OF WATER DEPTH ON DILUTION

The dilution increases with the length of the plume (or, for a horizontal discharge, the depth of water between the discharge port and the seabed). Thus, the second set of dilution simulations explored the effect of water depth on initial dilution. These simulations were made for the “worst-case” of slack water, and for various stages of the tide. Four cases were examined using the 6-port configuration: · 10.2 m - Low tide and fully laden vessel; · 12.5 m - Low tide and empty vessel; · 13.2 m - High tide and fully laden vessel; · 15.5 m - High tide and empty vessel.

Figure 4 shows the predicted initial dilution for these depth cases with a discharge of 450,000kL/d. At low tide and with fully laden vessel, the initial dilution is 20:1, as shown in Figure 4 (corresponding to the dilution for the same case in Figure 3). This is the lowest dilution for the 6-port configuration.

At high tide, or with a part or fully empty vessel, the depth below the water is greater and the predicted initial dilution also is greater. Thus over a tide cycle, and during the period when the LNG vessel is being unloaded, the dilution will vary from 20:1 to 26:1. It is apparent that depth of water is a significant parameter, and consideration of the stage of the tide is required to assess the environmental effects of the proposed discharge.

Figure 4. Effect of Water Depth on Initial Dilution 30 Effect of Water Depth on 6-port Dilution

25

20

15

10 Predicted Inttial Diluition

5

0 10.2 m 12.5 m 13.2 m 15.5 m Depth Below Discharge Ports AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 9

6. EFFECT OF DISCHARGE RATE ON DILUTION

For flow situations where the dilution is mostly due to gravity (i.e., dense plume with a long path or buoyant plume), the dilution increases in proportion to the depth of water but decreases in proportion to the discharge rate. In simple terms, a higher rate of discharge results in lower dilution, while a lower rate of discharge results in higher dilution.

For the Crib Point situation, the density difference between the plume and the ambient seawater is small (only 0.8 kg/m3 for a 7°C temperature difference), and the dilution is more strongly influenced by momentum-induced mixing than by the effects of gravity. For a fixed port diameter, the velocity decreases with the discharge rate, and hence the momentum-induced mixing decreases with the discharge rate. Thus, there are two processes to be considered, which tend to counter-balance each other. The dilution increases as the discharge decreases, but also decreases as the velocity decreases.

To establish the outcome in the Crib Point situation, a series of runs were made for the 6-port case with three different flow rates: · 75,000 kL/d per port (full production of 450,000 kL/d via six ports), · 50,000 kL/d per port; and · 35,000 kL/d.

Figure 5 shows the predicted initial dilution for these discharge cases (assuming the diameter of the discharge ports remains fixed). Overall, the dilution decreases as the flow rate decreases, from a maximum of 20:1 at full flow (450,000 kL/d or 75 kL/d per port) to a minimum of 15:1 at 35,000 kL/d/port. The dilution would become even smaller at discharge rates below 35,000 kL/d/port.

Figure 5. Effect of Discharge Rate on Dilution for 6-port Option AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 10

To further illustrate the effect of discharge rate (or discharge velocity, as the port diameters are fixed), a series of runs also were made for the single-port case with three different flow rates: · 450,000 kL/d (full production), · 300,000 kL/d (2-skid production), and · 150,000 kL/d (1-skid production),

Figure 6 shows the predicted initial dilution for these discharge cases. Overall, the dilution decreases as the flow rate decreases, from a maximum of 10:1 at 450,000 kL/d to a minimum of 7:1 at 150,000 kL/d.

Figure 6. Effect of Discharge Rate on Initial Dilution

24 Effect of Discharge Rate on Dilution - Single Port

21

18

15

12

9 Predicted Initial Dilution

6

3

0 450,000 300,000 150,000 Flow Rate, kL/d

It is apparent from Figure 6 that the momentum-induced mixing is decreasing faster than the flow rate, so that initial dilution declines faster than the discharge rate does. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 11

7. EFFECT OF NUMBER OF PORTS ON DILUTION

In this section, the discharge options evaluated are: · Single port of 1.1 m diameter on starboard side; · Dual ports of 0.9 m diameter (one on each side); · Four ports of 0.5 m diameter (two on each side); and · Six ports of 0.45 m diameter (three on each side).

AGL advised that a diffuser with a larger number of ports (i.e. greater than six ports) was not conventional practice for a FSRU and so that option is not analysed in this report.

To examine the effect of the number of discharge ports on dilution, the minimum initial dilution for each of the four options has been calculated for the case of a fully loaded vessel at low tide with the maximum discharge rate of 450,000 kL/d.

As would be appreciated from the discussions of cases above, higher dilutions will be achieved when: · It is high tide (compared to low tide); · The vessel is nearly empty (as ports are higher above the seabed); · The tidal velocity is higher than at slack water (see later discussion).

Figure 7 shows the predicted initial dilution for the four options concerning the number of ports. The single port option provides a dilution of 8:1 to 10:1 (from low tide to high tide); the 2-port option provides a dilution of 9:1 to 12:1, the 4-port option provides a dilution of 15:1 to 17:1; and the 6-port option provides a dilution of 20:1 to 26:1.

Figure 7. Effect of Number of Ports on Dilution – Constant Discharge

30

25 Effect of Number of Ports on Dilution

20

15

10

Predicted Initial Dilution 5

0 1-port 2-ports 4-ports 6-ports

Low tide High tide AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 12

In terms of the temperature of the resulting diluted field on the seabed: · A single port would produce a diluted cold-water field about 0.8°C cooler than ambient; · A 2-port option would produce a diluted cold-water field about 0.7°C cooler than ambient; · A 4-port option would produce a diluted cold-water field about 0.45°C cooler than ambient; and · A 6-port option would produce a diluted cold-water field about 0.33°C cooler than ambient.

More ports produce a higher dilution, as would be expected. Therefore, the question arises as to how many ports are necessary to avoid adverse environmental effects – and that question is answered in the following sections of this report. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 13

8. WHAT DILUTION IS REQUIRED?

The dilution required to achieve good mixing between the diluted field and the adjacent seawater is calculated from the minimum density difference that allows shear caused by tidal currents to erode and mix the cold-water field with the adjacent seawater.

This threshold condition is calculated from the Richardson Number (R), which is a dimensionless ratio that expresses the ratio of buoyancy forces to shear forces. The Richardson Number is widely used in investigating density flows in oceans, lakes and the atmosphere, and for the Crib Point situation is calculated as:

R = buoyancy / shear = g p D / P U2 where g is gravity, p is density difference, D is the depth of the stratified layer experiencing shear, P is ambient density and U is the tidal current speed.

The critical Richardson Number, below which fluids are dynamically unstable and turbulent, is widely accepted to be 0.25, based on extensive research. It has been demonstrated that R < 0.25 is a necessary condition for velocity shear to overcome the tendency of a stratified fluid to remain stratified (J S Turner, Buoyancy Effects in Fluids, Cambridge Univ Press, 1973).

The values for several of the parameters in the equation above are known, and the parameter that is to be established is p (density difference). Substituting the known parameters, R = g p D / P U2 = 9.8 x p x D /1025 U2 = p x D / 105 U 2 = 0.25

Predicted values of the field depth (D) and the tidal current (U) are presented in subsequent sections of this report. For a preliminary estimate of p, we can adopt the following values: D = 3 m; U = 0.1 m/s. Substituting these values: R = 0.25 = p x 3 / 105 x 0.01 = 2.8 p Hence p = 0.088 kg/m3.

This density difference of 0.088 kg/m3 corresponds to a temperature difference of 0.4°C. Thus the required minimum dilution is 7°C / 0.4°C = 17:1.

From these preliminary calculations, it is apparent that the single port and 2-port discharges will produce a field of cold water that is dynamically stable and will persist on the seabed until higher tidal velocities (than 0.1 m/s) occur.

A 4-port discharge option will be marginal – satisfactory at high tide but marginal at low tide with cold water pooling forming on the seabed.

On the other hand, the 6-port option proposed by AGL will produce a dilution that always exceeds 20:1 and thus the resulting diluted field will mix rapidly with ambient tidal currents.

In summary, the 6-port option will always achieve the dilution required to mix the diluted cold-water field into ambient seawater in the passing tidal flow at Crib Point. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 14

9. BATHYMETRY AT CRIB POINT

Figure 8 shows the bathymetry in the area of the Crib Point Jetty. The depth of the access channel, the turning basin and the berths are maintained at a minimum depth of 14.3 m below LAT (Lowest Astronomical Tide which is the lowest tide level which can be predicted to occur under any combination of astronomical conditions. There is a shallow bank to the north of Crib Point.

Figure 8. Bathymetry in Area of Crib Point Jetty AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 15

10. CURRENTS AT CRIB POINT

Currents at Crib Point are driven by many factors but principally by the diurnal tidal cycle. Typically, the flood tide currents (in the main channel, averaged over the depth) are in the range of 0.05 to 0.55 m/s while the ebb tide currents are slightly stronger at 0.05 to 0.65 m/s, but over a shorter period (Ref RH-DNV, 2015). The current patterns in the main channels are elliptical, with lateral currents at high and low tide, generated by the bathymetry of Western Port. Thus, there is seldom zero current speed, even at high or low tide.

Figure 9 shows the pattern of tidal currents in the bottom layer (seabed to 2 m above seabed) at Crib Point Jetty as derived from a hydrodynamic model run by Water Technology (2017). The peak flood tide current is 0.3 m/s while the peak ebb tide current averages about -0.33 m/s (negative current velocity is to the south).

Figure 9. Bottom Layer Currents at Crib Point Jetty

The tidal excursion, which is the distance a particle of seawater travels from low tide to high tide, is 4.3 km for the bottom layer currents. For the upper layers in the water column, the currents and therefore the tidal excursion is greater (at 6 km).

At low tide, the currents are weak (around 0.05 m/s) for a period of 30 minutes or so. If there was insufficient initial dilution in the descending plume, a pool of cold water could form under the vessel over this period when the diluted plume reaches the seabed and slowly spreads.

The currents are much stronger for most of the tide cycle. While the stronger currents increase the rate of initial dilution marginally, they increase the shear at the interface of the cool layer considerably, eroding and mixing any cold-water layer that forms at slack water. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 16

11. DEPTH OF COLD WATER LAYER

Figure 10 shows a schematic diagram of the hydrodynamic processes that influence dilution. The plumes of water start from the discharge ports at 7°C cooler than the adjacent seawater and is therefore 0.8 kg/m3 more dense than ambient seawater. Each plume descends to the seabed, diluting on the way due to shear between the descending plume and the adjacent seawater. The initial dilution is marginally greater at times of stronger currents. The subsequent calculations are for a single port discharge (as a conservative case scenario) as well as for the preferred design option of a 6-port discharge at times of low current speeds.

Figure 10. Diagram of Descending Dense Plume and Bottom Cold Pool

Figure 11 shows the behaviour of the cold-water field over the period of the 6-hour flood tide. The upper plot in Figure 11 shows the tidal current (smoothed by averaging several flood tides). The current speed rises from 0.05 m/s at low tide to a peak of 0.3 m/s and then falls back to 0.05 m/s at high tide (Water Technology, 2017).

The central plot in Figure 11 shows the excursion of particles each half-hour of the flood tide. In this conservative single-port case, the excursion is only 90 m at slack water but increases to 540 m over the half hour at times of peak currents.

The lower plot in Figure 11 shows the thickness of the cold-water pool formed on the seabed at the base of the plume for the single port option. At slack water, the layer is predicted to be 2.5 m thick. As the current speed increases, the layer thickness is less, as the shear due to the passing current pulls the diluted plume along the seabed. At the peak current speed, the layer is just under 1 m thick. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 17

Figure 11. Behaviour of Cold Plume in Flood Tide Period – Single Port

0.4

0.3

0.2

0.1 Current Speed, m/s 0 0 1 2 3 4 5 6

700 600 500 400 300 200

itnenorthDistance \, m 100 0 0 1 2 3 4 5 6

Travel Distance Length Width

Layer thickness - single port option 3.0 2.5 2.0 1.5 1.0

Thickness, m 0.5 0.0 0 1 2 3 4 5 6

Layer thickness

Figure 12 shows the thickness of the cold-water pool that could form on the seabed for the proposed 6-port option. The field is thin and rapidly eroded by the passing currents, as described in the next section.

Figure 12. Layer Thickness - Six Port Option

Layer Thickness 6-port Option 3.0 2.5 2.0

m 1.5 1.0 0.5

Layer Thickness, 0.0 0 1 2 3 4 5 6 AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 18

12. CALCULATED DYNAMIC RICHARDSON NUMBER

From the geometry of the diluted field on the seabed, the density difference and the current speed, the Richardson Number can be calculated for each half hour of the flood tide. The result is shown in Figure 13 for the single port option.

At and near low and high water – the times with weak currents - the Richardson Number exceeds 0.25 (indeed, it exceeds 1.0) and there is very little mixing. Thus, the stratified dense field formed at these times is not quickly mixed into the ambient seawater current.

However, for most of the flood tide, the currents are sufficiently strong to produce a Richardson Number below the critical value of 0.25 and there is a moderate to high rate of vertical mixing.

Figure 13. Richardson Number and Mixing of Dense Field - Single Port

0.75

Very little mixing 0.50

0.25 Mixing if R < 0.25 Richardson Number

0.00 0 1 2 3 4 5 6

The lower figure in Figure 13 shows, for each half-hour time step, the thickness of the layer of cooler water on the seabed (blue line) and the rate of erosion or mixing of the more dense layer (pink line). When the blue line is above the pink line, the field is thicker than the rate of mixing, and so most or a remnant of the cooler layer persists to the next time step.

On the other hand, when the pink line is above the blue line, the rate of vertical mixing field is greater than the depth of the cooler layer and so the cooler layer is entirely mixed into ambient seawater in that time step. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 19

For the proposed 6-port option, the rate of vertical mixing is greater than the depth of the cooler layer except for a brief period at slack water. Thus, with the 6-port option, the cooler layer is entirely mixed into ambient seawater and into the passing seawater for almost all the tide cycle, expect (perhaps) for a short period at slack water.

Figure 14. Richardson Number and Mixing of Dense Field - 6-port Option

0.75 6-port option

0.5

0.25 Mixing if R < 0.25 Richardson Number

0 0 1 2 3 4 5 6 Hour During Tide Cycle

4.0 3.5 6-port option 3.0 2.5 2.0 m 1.5 1.0 0.5 0.0 0 1 2 3 4 5 6 Thickness and Entrainment, Layer thickness Erosion rate Hour During Tidal Cycle

The Water Technology computer model of currents predicts zero longitudinal current speed at slack water (averaged over the depth). In practice, based on field measurements of currents in Western Port, when longitudinal currents are close to zero at slack water there is a small lateral current caused by draining (or filling) of the mudflats and bays on the sides of the main channel. This is shown by the elliptical current vector formed over a full tidal cycle.

As a result, it is considered that the time for formation of a cooler layer on the seabed with the 6-port discharge option is probably 30 minutes or less, at times of slack water. In that case, the field will spread less than 200 m from the discharge ports, and thus be contained within a field of 200 m radius that is well within the defined port waters of the Port of Hastings (as defined by the Victorian Regional Channels Authority, 2018).

In contrast, with a single port discharge, the time for formation of a cooler layer on the seabed is probably 1 hour or more, over the period of slack water and weaker tidal currents. In that case, the field will spread about 600 m from the discharge ports, although it will still be contained within the defined port waters of the Port of Hastings. As stated above, this single port discharge option is presented for comparison purposes only. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 20

13. DYNAMIC BEHAVIOUR OF DILUTED COLD-WATER FIELD

The rate of vertical mixing has been assessed from the experimental data published by Keulegan (1949) and Kato and Phillips (1969). These experiments show that the vertical mixing rate is proportional to the shear velocity (effectively higher shear creates internal waves which create upward mixing) and inversely proportional to the density difference between the fluids.

The resulting mixing rate varies from 0.0002 m/s at a current speed of 0.1 m/s to 0.0010 m/s at a current speed of 0.5 m/s. These may appear to be small, but they correspond to mixing rates of 0.72 m/hour to 3.6 m/hr, which are significant rates of mixing in comparison to a field thickness of 1.0 to 2.5 m.

The lower plots in Figures 13 and 14 show the thickness of the cold-water pool formed on the seabed at the base of the plume (blue line) and the mixing or erosion rate (pink line) expressed in metres/half hour. Figure 13 shows that, at slack water, the layer is 2.5 m thick and erosion is weak. However, as the current speed increases, the layer thickness decreases and the erosion rate increases. For the 2.5 hours with strong currents, the erosion rate in 30 minutes equals or exceeds the layer thickness. Thus at or near peak currents, the field is mixed into the ambient seawater current in 30 minutes or less. Figure 14 shows, for the 6-port option, a thinner layer only 0.5 to 1.5 m thick and erosion is generally greater than the depth of the field, so the diluted discharge is quickly mixed into the passing seawater.

As a check, it is noted that field measurements at the discharge from a desalination plant with a discharge rate of 5 m3/s (very similar to the proposed Crib Point FSRU) identified a stable dense field on the seabed that extended over a diameter of 800 m with a density difference 0.2 to 0.85 kg/m3 (due to slightly higher salinity). The vertical mixing rate for this dense field in the ocean (based on the measured initial dilution of 30:1) was 0.0003 m/s (corresponding to 1.1 m/hr). This measured mixing rate falls within the published range, and corresponds to a typical ocean current speed of 0.2 m/s (for the measured density difference).

The time scale for the data in Figures 13 and 14 is 30 minutes. A negligible cold- water layer will occur when the erosion in 30 minutes equals or exceeds the thickness of the cold-water layer on the seabed. The cold-water layer can only form when the erosion rate is small and insufficient to remove the layer in the 30-minute time interval.

For the period at and just after slack water, vertical mixing is slower and thus there is a potential for the formation of a cold-water layer if the current speed is less than 0.13 m/s, and the Richardson Number is above 0.25. In the next hour, however, that patch will be progressively eroded and mixed with the ambient seawater.

The results of calculations, on a 30-minute time step, show that the extent of the cold-water layer depends on the initial dilution (and thus the number of ports): · For a 6-port discharge, the field may form briefly at slack water and would extend for less than 200 m radius; · For a single-port discharge, the field would extend for 600 m north and 240 m wide. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 21

14. VELOCITY AND TRANSLATION OF PLUMES

At the proposed rate of discharge of 450,000 kL/d (equal to 5.2 m3/s) and a 7°C initial temperature difference, the discharge has a net excess density of 15 t/hr relative to ambient seawater. The discharge plume descends rapidly through the water column, slowing as it mixes with ambient seawater.

Figure 15 shows the predicted velocity of the plume during descent. Initially the velocity is high (over 5 m/s) but the velocity decreases rapidly in the first metre vertically of the decent (although, as shown in the next figure, this represents a considerable distance transversely). When the plume reaches the seabed, the plume velocity will be: · 0.40 m/s for a single port discharge; · 0.32 m/s for a 2-port discharge; · 0.25 m/s for a 4-port discharge; and · 0.22 m/s for a 6-port discharge.

Figure 15. Velocity of Plume at Various Distances (Seabed is zero depth)

3

1-port 2-ports 4-ports 6-ports

2.5

2

1.5 Velocity at seabed is 0.40 m/s for 1-port; 0.25 m/s for 4 ports; and 0.22 m/s for 6-

Plume velocity, m/s 1 ports

0.5

0 0 1 2 3 4 5 6 7 8 9 10 Distance above Seabed, m

The plume will have a mass flux of about 19 t/s for the single port discharge and 18 t/s for each plume in the 6-port discharge. This large mass of seawater moving at a moderate velocity will erode a pit where the plume reaches the seabed.

Another aspect of interest in the behaviour of the discharge plume is the extent of travel away from the FSRU. The discharge plume has a large mass flux (5.2 m3/s as noted above) and is discharged horizontally at a high velocity (around 5.4 m/s). Thus, the plume has a large horizontal momentum that conveys the plume a considerable distance from the discharge port. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 22

Figure 16 shows the predicted translation of the plume during descent for various port options. The single port option will travel 63 m laterally from the port before it reaches the seabed at low tide, and around 70 m at high tide.

Figure 16. Translation of Plumes for Various Port Options

70 1-port 2-ports 4-ports 15 degrees 6-ports

60

50

40

30

Travel distance from20 Port, m

10

0 0 1 2 3 4 5 6 7 8 9 10 Distance above Seabed, m

The 6-port option will travel 52 m laterally from the port before it reaches the seabed at low tide, and around 58 m at high tide.

Note that the predictions of initial dilution assume that the path of the plume is not impeded by the jetty or other structures or vessels. In our view, it is likely that the plumes will interact with the adjacent LNG vessel during LNG unloading operations, and this will reduce the travel distance of the plume and hence the initial dilution (although only when a LNG vessel is moored alongside the FSRU). The resulting dilution is then likely to match the 2-port option for the three ports on the offshore side, and match the 6-port option for the three ports on the inshore side.

For this reason, this report has presented the dilutions and cold-water field implications for a range of discharge options.

When a LNG vessel is moored beside the FSRU, it may restrict the path of the plume on the starboard side of the FSRU and the dilution could be temporarily reduced. This could occur about once a week over a 24-hour period. During the period of weaker currents near slack water, the diluted field could form a stable layer on the seabed about 2 m thick, extending for a maximum of 200 m distance. The layer formed at slack water will become mixed into the ambient seawater when currents increase an hour later in the tide cycle. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 23

15. CONCLUSION

This assessment concludes that discharged seawater would dilute rapidly after discharge, with the initial dilution at the seabed depending on the number and depth of discharge ports and the velocity of discharge. AGL’s preferred design is a 6-port discharge. Fewer discharge ports have been considered in this assessment for comparison purposes only.

Modelling shows that the initial dilution depends on the number of discharge ports. For the 6-port discharge option proposed by AGL, the lowest dilution would be 20:1 (at low tide and a vessel with a full LNG load) and the highest dilution would be 26:1 (achieved at high tide and a near-empty vessel).

For the period at and just after slack water, vertical mixing is slower and thus there is a potential for the formation of a cold-water layer on the seabed over that period.

A single port discharge was examined as a worst-case option and showed that a layer of cooler water at 0.8°C below ambient will form for a period of just under an hour at each slack water. The maximum extent of the layer for the single port discharge has been calculated from the balance between initial field thickness, shear due to ambient currents and vertical mixing. The layer will extend about 600 m north in the flood tide, and a similar distance to the south in the ebb tide. The layer will be a maximum of 240 m wide and thus be contained within the defined port waters of the Port of Hastings.

AGL’s preferred discharge configuration is for a 6-port discharge. For a 6-port discharge, the cold-water field may not form at slack water but if it does, it will extend for less than 200 m north and 120 m wide and have a temperature difference of only 0.3°C from ambient seawater. The layer will be contained within the defined port waters of the Port of Hastings. The cold-water layer may not form with the 6-port option if there are sufficient lateral currents over slack water at the discharge site.

When an adjacent LNG vessel restricts the path of the plume, the dilution could be reduced. This could occur about once a week over a 24-hour period. In the weaker currents near slack water during this period, the diluted field could form a stable layer on the seabed about 2 m thick. The layer formed at slack water will become mixed into the ambient seawater when currents increase later in the tide cycle.

To achieve effective dilution, the discharge ports should be horizontal, near the water surface and have a high discharge velocity (> 5 m/s). AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 24

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K Cederwall (1968) “Hydraulics of Marine Waste Disposal”, Report No 42, Hydraulics Division, Chalmers Inst of Tech, Goteburg, Sweden

RJ Charbeneau and ER Holley (2001) “Backwater Effects of Bridge Piers in Subcritical Flows”, Research Report No 0-1805-1, Centre for Transportation Research, Univ of Texas at Austin.

CSIRO (2016), “Sea-level Rise, Observations, Projections and Causes”, CSIRO Oceanography, Hobart

J B Hinwood and J C E Jones (1979), “Hydrodynamic Data for Western Port, Victoria”, Marine Geology, Vol 30, 47-63.

J B Hinwood. and I G Wallis (1985); "Initial Dilution for Outfall Parallel to Current." Proc. ASCE, J. Hyd. Div. Ill, 5,828-845.

H Kato and O M Phillips (1969) “On the Penetration of a Turbulent layer into a Stratified Field”, J Fluid Mechanics, 643-655.

G H Keulegan (1949) “Interfacial Instability and Mixing in Stratified Flows” Res. Nat. Bur. Stand. 43, 487-500

R Lee (2018), “Physical and Chemical Setting”, Ch 4 in Understanding the Western Port Environment”, Melbourne Water website.

K L Pun and S Law (2015) “Effects of Bridge Pier Friction on Flow Reduction in a Navigation Channel”, J Water Resources and Hydraulic Engineering, pp 326-331

National Tide Centre, BOM (2016) “Annual Sea Level Data Summary Report”, The Australian Baseline Sea Level Monitoring Project, Bureau of Meteorology

RH-DNV (2015) “Metocean Conditions at Existing Berths” Report to Port of Hastings

J S Turner (1973) “Buoyancy Effects in Fluids”, Cambridge Univ Press.

Victorian Regional Channels Authority (VRCA) (2018), VRCA Hastings Harbour Master’s Directions, March 2018 Edition.

Water Technology (2017) “Hydrodynamic and Water Quality Modelling – Western Port Bay”. Report to AGL Energy Ltd.

I G Wallis (1978) "Ocean Outfalls - Performance, Investigation, Construction and Cost", Water, 5, June.

I G Wallis (1981) "Verification of Ocean Outfall Performance Predictions", Proc. ASCE, J. Env. Eng. Div., _107_, EE2, 421-425. AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 25

I G Wallis (2016) "Outfall Construction Using Inclined Drilling", Internat Symp on Outfall Systems, Ottawa, IAHR, pp 201-209 AGL Gas Import Jetty Project – Plume Modelling of Discharge from LNG Facility 26

APPENDIX A: NEAR-FIELD MODELLING PARAMETERS

Parameter Unit Response Discharge rate m3/d 450,000 Temperature difference °C 7°C on exit from FSRU Depth of Water m Stern Min 12.8 Bow Min 14.7 Tide can add 3.3 m to these depths Depth of Ship m Fully Loaded 11.6 m Ballast only 9.3 m Vessel length m 294 m (285 m parallel length next to hull)

Discharge from Single Side Port Depth of port below sea level m 10.3 m above vessel base line, 100 m forward of stern, starboard side Diameter of port m 1.1 Angle below vertical deg 15

Discharge from Side Dual Ports Depth of ports below sea level m 8.5 m above vessel base line, close to bow of vessel Diameter of port m 0.9 each port Angle below vertical deg 15

Discharge from Multiple Ports Depth of ports below sea level m At CEE discretion Angle below vertical deg 0 (horizontal discharge)

Seawater inlets Depending on design, inlet may be through existing vessel sea chests High sea chest: Distance from stern: 55.2m, Height: 4.6m above Base Line (B.L.) Sea chest gratings follow hull shape

Low sea chest: Distance from stern: 54.0m, Height: 3.4m above Base Line (B.L.) Sea chest gratings follow hull shape

If the regas system is mounted in the bow, two options are under consideration: Caisson type pumps (internal) with the inlet strainers (retractable during sailing conditions) underneath the fore ship (ie at the base of vessel)

Sea chests on port and starboard side, at similar elevation to main sea chests, feeding into the same crossover line.

Attachment 6

Report to: Jacobs Group (Australia) Pty Ltd

AGL Gas Import Jetty Project Crib Point, Western Port

Chlorine in seawater heat exchange process at Crib Point

FINAL

30 August 2018 AGL Gas Import Jetty Project Crib Point, Western Port

Chlorine in seawater heat exchange process at Crib Point

Contents Executive Summary 1 1 Introduction 3 1.1 Project overview 3 1.2 Background 3 1.3 Purpose of this report 4 2 Free Residual Chlorine 5 2.1 Bromine compounds from free chlorine in seawater 6 2.2 Analytical methods for Free Residual Chlorine and Bromine 8 2.3 Factors influencing TRC reduction rate 8 2.4 Need for second and third stage chlorine reduction rate trials at Crib Point 11 3 Regulatory guidance for chlorine in marine ecosystem protection 13 4 Modelling chlorine reduction at Crib Point 15 4.1 Method 15 4.1.1 First phase 15 4.1.2 Second and third phase 15 4.2 Three phases of chlorine reduction in seawater 17 5 Chlorine reduction, FSRU seawater processes and dispersion modelling 19 5.1 Chlorine concentration in discharge 19 5.2 Initial physical dilution phase 20 5.3 Nearfield phase (6 hours) 22 5.4 Net outcome of chemical reduction and physical dilution 23 6 Ecotoxicity test of chlorine in Crib Point seawater 24 6.1 Sub-acute sea urchin fertilisation 1-hour ecotoxicity test 24 6.2 Sea urchin fertilisation test conditions 26 6.2.1 Test temperature 26 6.2.2 Test concentration range 26 6.3 Toxicity test results 27 6.4 Interpretation of ecotoxicity test results 28 6.5 Comparison with Guidance values 28 7 Conclusion 29 7.1 Implication of chlorine reduction and toxicity tests for Crib Point results 29 7.2 Synthesis of factors affecting chlorine concentration targets for Project 29 8 References 31 AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process ii

Tables Table 1. Chlorine ecosystem protection guidance values ...... 14 Table 2. Total chlorine in seawater trials using Crib Point seawater, November 2017 . 16 Table 3. Initial physical dilution of heat exchange cold-water discharge ...... 20 Table 4. Chlorine concentration after initial dilution and 20 second chemical reaction . 21 Table 5. Net remaining chlorine after initial dilution and 6 hours chemical reaction ..... 23 Table 6. Chlorine concentration after initial dilution and 6 hours chemical reaction ..... 23 Table 7. Chlorine concentrations used in toxicity test ...... 26 Table 8. Statistically calculated outcomes of toxicity test ...... 28 Table 9. Compiled environmental guidance and project chlorine concentrations...... 30

Figures Figure 1. Hypochlorite – hypochlorous acid equilibrium (Wahab 2012) 5 Figure 2. Hypobromite – hypobromic acid equilibrium (Wahab 2012) 7 Figure 3. Residual chlorine concentration reduction with salinity and temperature 8 Figure 4 TRC reduction at 13.5°C, 23.5°C, 33.5°C and 43.5°C 9 Figure 5. Residual chlorine and corresponding bromoform over >240 hours 10 Figure 6. Examples of first, second and third phase chlorine reduction in seawater 11 Figure 7. Total chlorine in unfiltered seawater, November 2017 16 Figure 8. Normalised chlorine in unfiltered seawater, November 2017 17 Figure 9. Chlorine reduction rates in unfiltered and filtered seawater 18 Figure 10. Percent chlorine reduction in seawater 20 Figure 11. Percent chlorine reduction in second phase 21 Figure 12. Percent chlorine reduction in second and third phase 22 Figure 13. Sea urchin Heliocidaris erythrogramma under Crib Point jetty 25 Figure 14. Fact sheet for sea urchin fertilisation toxicity test 25 Figure 15. Graphical results of ecotoxicity test 27 AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process iii

Report to Report prepared by Scott Chidgey CEE Pty Ltd Unit 4, 150 Chesterville Rd Cheltenham, VIC, 3192 Ph. 03 9553 4787 Email. [email protected]

CEE (2018)

Cover photo: Cribb Point Jetty (S Chidgey)

Document History

Document Details Job Name AGL Gas Import Jetty Project Job No. IS210700 Document Chlorine in seawater heat exchange process at Crib Point

Revision History Revision Date Prepared Checked By Approved By by Final (Ver 01) 27/07/18 Name S. Chidgey S Ada S Ada Final (Ver 02) 30/08/18 Name S. Chidgey S Ada S Ada AGL Gas Import Jetty Project Chlorine in seawater heat exchange process at Crib Point

EXECUTIVE SUMMARY AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

AGL has selected Crib Point Jetty in Western Port as the preferred location for the Project as it is an established, operating port. Western Port has an area of approximately 680km2 and estimated volume of 0.8km3.

The FSRU will be continuously moored to receive LNG cargos from visiting LNG carriers, store the LNG and re-gasify it as required to meet demand for high pressure pipeline gas.

Regasification involves the heating of LNG using the ambient heat of seawater in Western Port. A daily volume up to 450,000 kL (450 ML/day) of seawater from Western Port will be pumped at a rate of 5.2 m3/s through heat exchangers in the FSRU. Seawater contains a range of marine biota and propagules that can attach to the pipes and grow into larger individuals that can block the heat exchanger pipes. This biological process can be prevented by the addition of a biofouling inhibitor at the intake to prevent ‘biofouling’. In this case, the biofouling inhibitor is produced by electrolysis of seawater at the intake to produce chlorine and hypochlorite.

AGL engaged Jacobs Group (Australia) Pty Ltd and their specialist subconsultants to investigate the potential impacts of the seawater intake/discharge arrangements on environmental conditions in Western Port. Desktop studies were undertaken to investigate the hydrodynamics of Western Port and the ecological effects of the seawater intake and discharge.

The scope of this assessment was to review potential implications to the marine ecosystem of any residual chlorine in the discharge from the FSRU heat exchange discharge. This report was prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), · A referral under the Victorian Environment Effects Act 1978, and Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act).

Section 3 of ANZECC National Water Quality Guidelines provide trigger values for “Chlorine” (free chlorine) to protect freshwater aquatic environments. The guidelines provide a trigger value of 3 µg Cl/ L (0.003 mg/L) for 95 % ecosystem protection and 1 µg Cl/L (0.001 mg/L) for 99 % ecosystem protection in freshwater aquatic environments. ANZECC does not list a AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 2 trigger for chlorine in marine (seawater) environments, but recommends use of the 3 µg Cl/ L (0.003 mg/L) trigger as “an indicative interim working value” in marine environments.

Modelling of the seawater discharge via six discharge ports, as proposed by AGL, and desktop and laboratory studies of chlorine behaviour and toxicity in seawater showed that a combination of dilution and time to react with seawater constituents in the marine environment would result in environmentally safe concentrations of chlorine that will protect beneficial uses of the seawater returned to Western Port. Chlorine concentrations in the water discharge will decrease along a gradient from the points of discharge, reaching ANZECC (2000) and USEPA (1985) guideline objectives within an area extending 200 m downstream (north and south) and 60 m east and west of the discharge. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 3

1 INTRODUCTION 1.1 Project overview AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

Jacobs Group (Australia) Pty Ltd (Jacobs) was engaged by AGL to undertake planning and environmental assessments for the AGL Gas Import Jetty Project. Jacobs engaged CEE Environmental Scientists and Engineers to define the marine environmental characteristics and identify key potential risks to the marine environment from the development and operation of the Project.

1.2 Background The regasification of LNG at Crib Point will involve the use of ambient seawater to transfer heat for increasing the temperature of the LNG into a gaseous form. The LNG and ambient seawater will pass through a heat exchanger system which includes small metal pipes with high surface area to optimise heat exchange.

Seawater contains a range of marine biota and propagules that can attach to the pipes and grow into larger individuals that can block the heat exchanger pipes. This biological process can be prevented by the addition of a biofouling inhibitor at the intake to prevent ‘biofouling’ in heat exchanger pipes. In this case, the biofouling inhibitor is produced by electrolysis of seawater at the intake to produce chlorine and hypochlorite (similar to saltwater swimming pool chlorinators).

The seawater discharged from the FSRU heat exchanger will contain residual chlorine from electrolysis of seawater at the intake – the residual chlorine will be managed at less than 0.1 mg Cl2/L. Electrolysis of seawater creates chlorine, which rapidly reacts in seawater to form a range of short-lived toxicants including hypochlorite and various bromine oxidants. Residual chlorine chemicals in the seawater discharge at Crib Point is recognised as a potential risk to marine environmental values in the vicinity of Crib Point.

The reduction of chlorine in the environment after discharge from the FSRU at a concentration of 0.1 mg Cl2/L was indicatively modelled by Water Technology (2017) using reduction rate formulae and coefficients from the literature and Water Technology’s validated hydrodynamic model for Western Port.

It was recognised that chlorine reduction rates in seawater were dependent on a range of factors including water temperature, local seawater quality, discharge arrangements and initial chlorine concentration. CEE were engaged to review literature, measure chlorine reduction rates in Western Port seawater (in the laboratory) at temperatures representing low, median and upper seawater at Crib Point and to test the toxicity of chlorine in Western Port seawater on a local species. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 4

1.3 Purpose of this report The purpose of this report was to assess potential implications to the marine ecosystem of any residual chlorine in the discharge from the seawater heat exchange discharge. The objectives are to: · Provide information on chlorine chemistry and behaviour in seawater, · Model chlorine reduction in the heat exchange discharge, · Undertake marine ecosystem toxicity testing of residual chlorine, · Determine chlorine guidance values for protection of marine ecosystem values, · Assess the extent of effects of the chlorine content in the seawater discharge on the marine ecosystem in Western Port, and · Inform the definition of the extent of a regulatory mixing zone for the seawater discharge.

This report was prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), · A referral under the Victorian Environment Effects Act 1978, and · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act). AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 5

2 FREE RESIDUAL CHLORINE Chlorine produced by electrolysis of seawater rapidly converts to hypochlorite as well as hypochlorous acid (HOCL). The equilibrium between the three chemicals is pH dependent and the group of all three chemicals is termed Free Residual Chlorine (FRC) or just Chlorine (Cl or Cl2) for analytical reporting purposes. FRC is used in a variety of applications, including drinking water sterilisation, domestic bacterial disinfection, swimming pool disinfection and algal control, sewage disinfection and biofouling inhibitor controlling biological growth in seawater heat exchangers.

FRC can be conveniently produced by electrolysis of chloride ions in seawater (Figure 1) for disinfection and control of biological growth in industrial heat exchange systems. This is the process proposed to control biological fouling in the FSRU facility at Crib Point.

Figure 1 shows: · The production of free chlorine from chloride ions in seawater by electrolysis, · The equilibrium in water between the oxidants chlorine (Cl2), hypochlorite (HOCl) and hypochlorous acid (OCl-), and · The effect of pH on the equilibrium between hypochlorite and hypochlorous acid.

The pH of seawater is approximately 8.1, so most of the FRC is hypochlorous acid (OCl-).

Electrochemical generation of chlorine from seawater - 2Cl + 2e Õ Cl2

Hydration equilibrium of chlorine to hypochlorite and hypochlorous acid - Cl2 + H2O Ö HOCl Ö OCl

Figure 1. Hypochlorite – hypochlorous acid equilibrium (Wahab 2012)

Concerns over the effects of FRC in aquatic environments often relate to the formation chloramines, which occur when chlorine components combine with ammonia or other nitrogenous compounds. Chloramines are commonly formed during the disinfection of domestic wastewater effluent due to the relatively high concentration of ammonia and organic material. “Total Residual Chlorine” (TRCs) is usually measured as the toxic residual - in chlorinated wastewater and is the sum of free chlorine (Cl2, OHCl and OCl ) and combined chlorine (chloramines). AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 6

Ammonia concentration is considerably lower in Western Port seawater (typically <0.01 mg/L, EPA database) than municipal effluent (0.5 mg/L to 5 mg/L in secondary effluent), and so there is negligible potential for formation of significant quantities of chloramines (or bromamines as discussed below) from chlorination of Western Port seawater. Hence, in seawater with relatively low ammonia and organic matter, TRC is the same as FRC.

FRC decomposes through a number of reduction/oxidation processes resulting in off-gassing of chlorine, formation of salt (chloride), acid (HCL) and reaction with organic matter including bacteria and other biota.

Seawater also contains bromide (Br-), which is another halogen chemical. FRC components react rapidly with the bromide in seawater to form bromine equivalents of the free chlorine chemicals. This process and its implications are discussed below.

2.1 Bromine compounds from free chlorine in seawater Chlorine, hypochlorite and hypochlorous acid react rapidly (gain electrons) when added to seawater due to the presence of bromine and other constituents in seawater. Bromine is present in seawater as the salt Br- at a concentration of approximately 70 mg/L (approximately 0.9 mM). Bromine and chlorine are both halides and have similar oxidative characteristics, although chlorine is the strongest oxidant and forms first when an electrical current is passed through seawater.

Following the addition of free chlorine to seawater, there is a rapid chain of reactions with the - - formation of a series of oxidant products including Cl2, HClO, ClO , HBRO, BrO and other halide derivatives. The redox reaction between free chlorine and bromide in seawater (Equation 1) is rapid.

HClO +Br- D HBrO + Cl- CLO- + Br- D BrO- + Cl- Equation 1. Free chlorine to free bromine in seawater (Equilibrium in seawater is complete to right hand side)

- The free, chlorine-based oxidants (Cl2, HClO, ClO ) are very short-lived (t1/2 ~ 0.2 s) in seawater and are mostly converted to back chloride ions in the marine environment (ANZECC 2000, Saeed et al 2015, Wahab 2012).

As a result, most of the chlorine-based oxidants convert the bromide (Br-) in the seawater to the equivalent bromine oxidants HBrO and BrO-. Hence the residual “FRC” is mostly bromine rather than chlorine based. (Common terminology continues to refer to the total amount of halogens (chlorine and bromine) in seawater as FRC as discussed below).

Bromine is also an effective disinfectant and biofouling inhibitor. Hence the conversion of chlorine oxidants to bromine oxidants in seawater does not result in a significant reduction in toxicity. In fact, the resulting toxicity from bromine products may be greater than chlorine in the pH range of the seawater. The relationship between free chlorine and bromine in seawater is discussed in a range of industry and regulatory documents on the discharge of disinfected municipal wastewater to marine environments, discharge of chlorinated cooling water to the marine environment and ballast water disinfection (Saeed et al 2015, USEPA 1985, USEPA 1991, USEPA 2017, Wang 2008, Wahab 2012). Chlorine and bromine are both halogens and behave in a similar way: chlorine (hypochlorite) is widely used as a domestic and industrial disinfectant and biofouling inhibitor; bromine (as hypobromite) is used as a disinfectant and algal growth inhibitor in swimming pools and spas. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 7

Bromine has advantages and disadvantages compared to chlorine (hypochlorite). Bromine is more effective as an oxidant at pH >7.6, and is less odorous than chlorine. Bromine is more expensive and less commonly available as a domestic or industrial chemical than chlorine and therefore is not used to the extent of chlorine in domestic or industrial applications. However, bromine oxidants are formed incidentally in seawater following chlorination and are therefore a key halogen biofouling inhibitor in chlorinated seawater systems. It is the bromine products of seawater chlorination, particularly hypobromic acid, that is the key growth inhibitor in biofouling prevention systems in seawater heat exchange systems such power station cooling systems and LNG regasification projects.

The other active products of chlorination are longer-lived and reduce in concentration as oxidation continues over periods of hours (see Section 2.3). In seawater with low natural ammonia concentration and a pH of approximately 8.0, hypobromic acid may represent 80 to 99 percent of the oxidants (Figure 2, Wang 2008, Wahab 2012). There are various decomposition (reduction) models of first-order and second-order reduction of chlorine in seawater (Saeed et al 2015).

Reduction rates are dependent on numerous factors including initial concentration, temperature, pH, UV light and the presence of other organic, inorganic and metallic constituents.

Figure 2. Hypobromite – hypobromic acid equilibrium (Wahab 2012)

Industry and regulatory agencies recognise that the impact assessment of chlorinated oxidants in seawater should include the total pool of halide derivative oxidants present. The pool of chemicals is sometimes termed total residual oxidants (TRO) (USEPA 1991, Wang 2008) or chlorine-produced oxidants (Burton 1977). Analytical methods used to determine total residual chlorine in freshwater and seawater also measure all halogenated oxidants, including bromine. USEPA uses the term Total Residual Chlorine or TRC as the measure of all chlorine-produced oxidants in freshwater or seawater. TRC and TRO is usually as - -1 expressed as mg Cl2 L 1 or mg Cl L for regulatory purposes (ANZECC 2000, USEPA 1985, 1991). For consistency with results reported in the literature, this report will use TRC. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 8

2.2 Analytical methods for Free Residual Chlorine and Bromine There are three generally-used methods for measuring free and total residual chlorine in freshwater and seawater samples: amperometric titration, DPD titration method and DPD colorimetric method (USEPA 2017, SOEQ 2014), which is relevant to Sections 2.3, 5 and 6 of this report.

Commercially available portable free chlorine measurement devices have detection limits of approximately 0.02 to 0.05 mg/L (Hach, Merck). These are fundamentally titration devices and measure concentration reasonably quickly (within minutes), although not instantly. As discussed above, the method for quantifying free chlorine or free bromine is the same. Most results are express the result for Total Residual Chlorine (TRC) as mg/L of chlorine. Hence, measurement of TRC in seawater is expressed as mg/L Cl or Cl2, even though most of the TRC is bromine and the proportion of chloramines or bromamines is negligible.

2.3 Factors influencing TRC reduction rate TRC concentration, and consequently TRC ecotoxicity, reduce in the marine environment in proportion to salinity, temperature, UV light and organic content of the ambient water. ANZECC and USEPA comment that the speed of reduction of TRC in the environment results in uncertainty of interpretation of ecotoxicity results from bioassays, which are usually longer in duration than 24 hours.

USEPA field procedures advise that TRC measurement “must be conducted within 15 minutes of sample collection” (USEPA 2017). TRC reduction rate needs to be determined over periods of hours to determine reduction rates that are relevant to dispersing and diluting chlorinated effluents. Similarly, toxicity bioassays need to reflect short term exposure effects (acute) over temporal scales relevant to discharge dispersion (hours), rather than chronic long-term exposure (days) which is unlikely in the broad environment, but may occur within approximately 20 m of a discharge port).

Laboratory based measurement of free or residual chlorine mass in clear seawater (Wahab 2012, Zeng et al 2009) demonstrate that TRC mass reduction rates depend strongly on salinity and temperature (Figure 3 and Figure 4). The reduction rate starting concentrations for these tests was calculated from the amount of chlorine (as hypochlorite) added to a volume of seawater.

Figure 3. Residual chlorine concentration reduction with salinity and temperature (Zeng et al 2009) AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 9

Figure 3 shows the reduction in the mass concentration of chlorine measured intensively over 30 minutes. The figure shows a rapid reduction in mass concentration of chlorine in less than two minutes from addition of hypochlorite to seawater. By contrast there is negligible reduction in chlorine distilled water. The initial reduction in chlorine is salinity and temperature dependent.

The subsequent reduction in chlorine from 5 minutes to 30 minutes is relatively linear for different salinities at the same temperature, but appears to be logarithmic or exponential for the variation in temperature. Figure 4 shows the reduction in mass concentration of chlorine in seawater at different temperatures over 96 hours. Note that the fitted curves in some graphs asymptote above zero, whereas concentration at the limit of detection or zero is actually recorded.

Figure 5 shows the reduction in mass concentration of chlorine and the corresponding increase in bromoform mass concentration over more than 240 hours. Both figures include exponential curves to fit the data. The figures show the initial rapid reduction in free chlorine concentration followed by the slower reduction to zero over subsequent days.

Figure 4 TRC reduction at 13.5°C, 23.5°C, 33.5°C and 43.5°C (Wahab 2012) AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 10

Figure 5. Residual chlorine and corresponding bromoform over >240 hours (Saeed et al 2015)

Models of chlorine reduction in seawater have been described in terms of a first order reduction model for a curve fitted to the data from the beginning of the test to completion (Equation 2):

-kt C(t) = C0e Equation 2. First order chlorine concentration reduction model

Two-component exponential reduction models also are used in recognition of the different rates in chemical reactions that occur between the initial rapid phase and subsequent slower phase of the chlorine reduction process:

-k t -k t C(t) = C0 (Ae 1 + (1-A) e 2 ) Equation 3. Two component chlorine reduction rate model (Saeed et al 2015) AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 11

Figure 6. Examples of first, second and third phase chlorine reduction in seawater

The initial reduction rates are too rapid for conventional analytical methods to measure the starting concentrations. Hence starting concentrations must be estimated. For the same reason, there is likely to be variation in measured concentrations in the first minutes of experiments due to rapid reduction in concentrations and the time required for analysis.

Each of these phases will be associated with different stages of the heat exchange and dispersion in the marine environment at Crib Point.

2.4 Need for second and third stage chlorine reduction rate trials at Crib Point It is proposed that chlorine will be generated at the inlet to the heat exchanger system of the FSRU at Crib Point. The free chlorine will rapidly proceed through the first phase of reduction in minutes, while it passes through the front end of the heat exchange system. The first rapid reduction phase should be complete by the time the seawater has reached the discharge point, so that all free chlorine will have already been converted to free bromine equivalents, and the disinfectant reduction will be proceeding at the slower, second phase rate.

Initial modelling of the FSRU discharge at Crib Point (Water Technology 2017) reduction model using the chlorine concentration of 0.1 mg Cl2/L predicted by AGL at the discharge point. This approach to estimating chlorine concentration at a point in time includes use of a first or second order decay formula to fit the first, second and third phases of chlorine reduction with a (decay) coefficient that is specific to a particular water temperature. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 12

This method is satisfactory for estimating chlorine concentrations over the far-field (> 500 m) but may over-estimate the loss rate of TRC in the FSRU discharge at distances less than 500 m (near-field) because it includes the rapid first stage of loss chlorine, which occurs within the heat exchanger. By the time the seawater reaches the discharge point, where environmental modelling commences and the initial concentration has dropped from 0.5 to 0.1 mg Cl2/L, chlorine reduction processes will be in their slower, second or third phases.

Incorporation of chlorine reduction rates into hydrodynamic mixing models of dispersion should include only the slower, post-first phase rate applied to the chlorine concentration at the point of discharge. Hence trials of reduction rate in Crib Point seawater were designed for and implemented for this study as reported in Section 4. The reduction rates were then applied to near-field dilution process models reported in CEE 2018a. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 13

3 REGULATORY GUIDANCE FOR CHLORINE IN MARINE ECOSYSTEM PROTECTION ANZECC and USEPA discuss the determination of safe levels for TRC in the aquatic and seawater environments. TRC is determined to be an appropriate measure of chlorine- produced oxidants in both environments. Safe environmental concentrations for chemicals are determined by ANZECC and USEPA from statistical analysis of species sensitivity distribution resulting from numerous rigorously performed bioassays on suitable aquatic plants and animals. These bioassays may expose biota (mostly invertebrates and waterweeds) or developing biota (seeds, gametes, fertilisation processes or propagules) to a toxicant for hours, but are most often exposure is for days, typically 2 to 4 days.

Section 3 of ANZECC National Water Quality Guidelines provide trigger values for “Chlorine” (free chlorine) to protect freshwater aquatic environments. The guidelines provide a trigger value of 3 µg Cl/ L (0.003 mg/L) for 95 % ecosystem protection and 1 µg Cl/L (0.001 mg/L) for 99 % ecosystem protection in freshwater aquatic environments. However, there is not a trigger for chlorine in marine (seawater) environments. ANZECC explains that: “In seawater, reaction with bromine results in formation of chloride ion and HOBr”, but does not provide a marine ecosystem protection level.

The ANZECC guidelines recognise three levels of ecosystem protection described below with the corresponding ecosystem protection level. 1. 99 percent protection: High conservation/ecological value systems – including reserves such as Ramsar wetlands. 2. 95 percent protection: Slightly to moderately disturbed systems 3. 95 percent protection: Highly disturbed systems, although “lower protection levels…may be accepted by stakeholders”

Further detailed discussion of chlorine as a toxicant in Section 8.3 of ANZECC, states that “Chlorine does not persist for extended periods in water but is very reactive and its by- products persist longer”. Hence, toxicity limits in ANZECC were derived from measurement of total residual chlorine as µg Cl/ L, and that, in marine water containing iodide and bromide, total residual oxidants were measured as µg Cl per L. The ANZECC trigger values for chlorine include chloramines and bromine oxidants as total chlorine produced oxidants. ANZECC further states that the 3 µg Cl/ L for 95 % ecosystem protection trigger for freshwater was considered of low reliability but was “adopted as a marine low reliability trigger value, to be used only as an indicative interim working value.” (No value was discussed for 99 % marine species protection, and no total residual chlorine values are listed for marine waters in ANZECC Table 3.4.1 Trigger Values for Toxicants.)

USEPA 1985 notes that the bioassays used to determine USEPA environment protection concentrations for TRC required flow-through systems to maintain the concentration of TRC at constant levels throughout the period of longer term tests and rejected the results of short term tests (3 hours). USEPA considered, however, that the results of the short-term tests were “useful for modelling purposes and for making decisions concerning this particular application”, in this case “to simulate discharges from specially controlled chlorination of cooling systems”. Hence, USEPA long term TRC criteria for ecosystem protection are conservative with respect to planktonic or mobile biota and are most relevant to biota constantly exposed to elevated chlorine concentrations such as those within the heat exchangers or attached to substrates that are constantly exposed to the discharge stream such as those attached to the jetty or in the seabed in the shipping basin. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 14

A summary of the ANZECC and USEPA ecosystem protection guidance values for TRC is provided in Table 1.

Table 1. Chlorine ecosystem protection guidance values Agency Protection level Value, mg/L ANZECC 2000 95% species protection, freshwater and marine* 0.003 USEPA 1985, 1991 Four day mean (chronic), marine 0.0075 USEPA 1985, 1991 One hour mean (acute), marine 0.013 *Value for marine ecosystem “indicative interim working value”.

These concentrations are close to or below the limits of practical detection (0.01 mg/L).

A key difficulty in establishing National trigger values is related to the rapid reduction of these oxidants in toxicity tests, particularly in relation to temperature. In one example, “Higher temperatures around 25°C resulted in complete loss of measurable residual chlorine and chloramines from the test vessels within 24 hours”.

This is consistent with our review of chlorine chemistry and the chlorine reduction experiments for the Project described in this report. We conclude that the toxicity of discharges containing TRCs will vary between seasons according to water temperature and the sensitivity of regional and seasonal biota.

Temperatures in Western Port range from approximately 11°C up to 22°C over the year and the discharge from the FSRU heat exchanger is a further 7°C below ambient. Hence loss rates are lower at these temperatures as the trials in Section 5 demonstrate, and chlorine loss in the Western Port ecosystem will be substantially lower than those demonstrated in the warmer environments reviewed in Section 2.3.

Trials to determine chlorine reduction in Crib Point seawater at temperatures that occur at Crib Point were designed and implemented as documented in Section 4. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 15

4 MODELLING CHLORINE REDUCTION AT CRIB POINT The chlorine reduction rate in Crib Point seawater was determined in trial laboratory tests specifically for the initial assessment program. The trial focused on the reduction of chlorine after the first rapid initial phase that occurs over the first four minutes of chlorine addition. Hence, the trials focused on the hours of chlorine reduction after the first initial phase (taken as four minutes in this case).

4.1 Method Seawater was collected from Stony Point Jetty near Crib Point in Western Port and transported to Ecotox Services environmental laboratory in Sydney. Hypochlorite was added in two volumes to represent 0.5 mg/L and 1.0 mg/L in unfiltered seawater at the commencement of second-phase chlorine reduction at three controlled temperatures representing the seasonal low (12°C), median (16°C) and high (20°C) seawater temperatures typical at Crib Point. Second-phase chlorine reduction was also measured in filtered seawater and artificial seawater at 16°C.

4.1.1 First phase The first measurement was taken four minutes after initial mixing of chlorine and seawater. This was recognized as the period when fastest chlorine reduction would occur within the exchange unit. This rate has low relevance to loss rates in the marine environment after discharge. The experiment focused on the second and third phase reduction rates.

4.1.2 Second and third phase Free and total chlorine was measured from four minutes after addition of the hypochlorite to coincide with the commencement of second-phase chlorine reduction. Chlorine was measured using a Merck Spectroquant Test Kit, which follows chlorine test procedures and QA/QC recommended by USEPA. There was less than 5 percent difference between free and total chlorine for all measurements.

The total chlorine measurements for all tests are shown in Table 2. Figure 7 shows the results for the unfiltered seawater tests. The table and figure show relatively rapid reduction in chlorine concentration from 4 minutes to three hours and a slower rate from four to 24 hours (240 to 1,440 minutes). The rate of reduction was slower for the lowest temperature (12oC) for both starting concentrations relative to the higher temperatures. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 16

Table 2. Total chlorine in seawater trials using Crib Point seawater, November 2017 Seawater TRC in Unfiltered samples Filtered Artificial 4 minute C0 0.5 mg/L 1 mg/L 1 mg/L 0.5 mg/L Temperature 12° 16° 20° 12° 16° 20° 16° 16° Time, min 4 0.44 0.39 0.48 1.02 0.94 0.98 1.03 0.48 9 0.47 0.33 0.41 0.99 0.88 0.93 0.99 0.40 14 0.42 0.32 0.40 0.97 0.87 0.90 0.95 0.32 20 0.41 0.28 0.36 0.95 0.85 0.87 0.92 0.27 35 0.40 0.29 0.35 0.93 0.83 0.87 0.90 0.24 45 0.39 0.28 0.33 0.92 0.83 0.83 0.89 0.23 60 0.38 0.23 0.33 0.90 0.82 0.83 0.86 0.19 90 0.35 0.20 0.29 0.91 0.77 0.79 0.83 0.16 120 0.33 0.17 0.24 0.86 0.74 0.76 0.75 0.14 150 0.32 0.23 0.85 0.72 0.74 0.74 0.13 180 0.31 0.15 0.22 0.81 0.71 0.70 0.73 0.11 240 0.30 0.14 0.22 0.81 0.67 0.71 0.70 0.12 540 0.24 0.11 0.20 0.77 0.52 0.62 0.54 0.10 1440 0.16 0.05 0.11 0.58 0.41 0.46 0.46 0.18

1.200 Free chlorine

1.000 UF12° UF16° 0.800 UF20°

0.600 UF12° UF16° 0.400 UF20°

0.200 ocnrto ,Concentration mg Cl2/L

0.000 4 0 200 400 600 800 1000 1200 1400 1600 Time, min

Figure 7. Total chlorine in unfiltered seawater, November 2017

The results were normalised to the starting concentration of each treatment to allow direct comparison of the reduction rates at different temperatures and treatment. The normalised results for unfiltered seawater at different temperatures and starting concentrations are shown in Figure 8. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 17

1.0 12°IC=1 0.9 16°IC=1 0.8 20°IC=1 12°IC=0.5 0.7 16°IC=0.5 0.6 20°IC=0.5 0.5 0.4 0.3 0.2 0.1 Percent chlorine Co remaining, = 4 min 0.0 0 200 400 600 800 1000 1200 1400 1600 Time, min

Figure 8. Normalised chlorine in unfiltered seawater, November 2017

The figure of normalised concentrations after the first phase shows: · Fastest second phase chlorine reduction rates occurred over the initial two hours at higher temperatures (16°C and 20°C) compared to lower temperature (12°C) at the lower starting concentration (0.5 mg/L). · Fast second phase chlorine reduction rates over the initial two hours at higher temperatures (16°C and 20°C) compared to lower temperature (12°C) at the same higher starting concentration (1.0 mg/L), although these were slower than the reduction rates for the same temperatures at the lower 0.5 mg/L starting concentration. · Reduction rates were substantially lower three hours after initial dosing than in the first two hours. Third phase would appear to occur approximately 3 hours after initial addition of chlorine.

4.2 Three phases of chlorine reduction in seawater The published and CEE results indicate three phases of chlorine reduction: · A first initial phase of reduction over the first minutes of addition of chlorine to seawater that is the result of redox reaction of free chlorine (oxidant) with readily available inorganic seawater constituents including bromine. · A second slower phase of redox reaction of free chlorine and bromine with relatively reactive organic seawater constituents. · A third slow phase of redox reaction of free bromine and any remaining chlorine with refractory (stable, relatively unreactive) organic seawater constituents.

These phases of chlorine reduction are consistent with process concepts of ‘chlorine demand’ in treated wastewater disinfections systems, with the addition of an initial rapid reduction due to the high concentration of inorganic salts in seawater compared to freshwater sewage. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 18

1.0

0.9 Unfiltered seawater at 16C 0.8

0.7 Liltered seawater at 16C 0.6 0.5 0.4 0.3 0.2 0.1 Normalised to initial Cl2 = 1 mg/L 0.0 0 200 400 600 800 1000 1200 1400 1600 Time, min

Figure 9. Chlorine reduction rates in unfiltered and filtered seawater

Figure 9 shows negligible difference between the filtered and unfiltered seawater results. This demonstrates that soluble constituents are the key to chlorine demand at the low suspended solids levels found in seawater and that the production of chlorinated organic compounds is expected to be low – especially compared to municipal wastewater discharges. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 19

5 CHLORINE REDUCTION, FSRU SEAWATER PROCESSES AND DISPERSION MODELLING The three phases of chlorine reduction in seawater identified in the previous section can be compared with the sequence of seawater in the regasification process: · Chlorine addition: passage of seawater past the chlorinator at the intake to the heat exchanger pipes prior to pump manifolds and pumps · Initial phase of rapid reduction (first five minutes): seawater passage from chlorinator, through pumps and front-end manifolds. · Second phase of reduction (five minutes to two hours): middle and latter parts of heat exchange pipework, through the discharge outlets and during initial dilution stage of mixing · Third phase of reduction (three hours to days): dispersing of already dilute chorine residuals with tidal currents.

5.1 Chlorine concentration in discharge The initial and residual chlorine concentration profile within the heat exchange system has been determined based on industry practise and experience. AGL advises that the chlorine concentration at the discharge outlet will be monitored and maintained at a concentration of 100 ppb or 0.1 mg/L. This will allow higher concentrations of chlorine at the intake and through the heat exchanger that will be sufficient to ensure that larvae and propagules do not survive to settle, grow and clog the pipes as they pass through the heat exchanger system.

The chlorine concentration at the outlet (0.1 mg/L) will be the result of the rapid phase chlorine concentration reduction processes due to first contact, mixing and reaction with seawater components within the heat exchanger. The chlorine compounds in the seawater at the discharge after passage through the heat exchanger may be, therefore, in the second phase of concentration reduction.

The previous sections of this report show that the rate of reduction of chlorine in seawater in the second phase of reduction is proportional to the concentration of chlorine at the start of the phase. Hence, rate of reduction is faster at a starting concentration 0.5 mg/L than starting at 1 mg/L as shown in the trial experiments.

The results of the percentage of chlorine remaining from a concentration of 0.5 mg/L at the start of the second phase is shown in Figure 10. It is expected that the rate of reduction of chlorine concentration in seawater at a concentration of 0.1 mg/L at the start of the second phase of reduction would be faster than those shown in the figure. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 20

100% 90% 12°IC=0.5

80% 16°IC=0.5 70% 20°IC=0.5 60% 50% 40% 30% 20% 10% ecn hoieeann,Co chlorineremaining, Percent = 4 min 0% 0 200 400 600 800 1000 1200 1400 1600 Time, min Figure 10. Percent chlorine reduction in seawater from starting concentration 0.5 mg/L

5.2 Initial physical dilution phase The initial dilutions were modelled under conservative one and two discharge port options and the preferred FSRU design, incorporating a six port discharge. These scenarios are modelled and discussed in CEE’s initial dilution and nearfield modelling report (CEE 2018a) and associated cold-water discharge ecosystem assessment report (CEE 2018b).

Initial dilution is achieved during the stage of discharge when the cold-water containing chlorine is discharged as a jet or jets of seawater at a temperature that is initially 7°C below the ambient surrounding seawater. The jet is therefore more than 1 kg/m3 more dense than ambient seawater and descends towards the seabed due to gravity and momentum. The jet entrains seawater and descends to the seabed, diluting on the way due to shear between the descending plume and the adjacent seawater. The initial dilution during the descent is higher at high tide compared to low tide and increases marginally at times of stronger tidal current. During periods of relatively low tidal currents and when modelled in the conservative case, the cold-water plume reaches the seabed and may spread to form a cold-water layer over the seabed in the shipping basin as shown in CEE 2018a and 2018b.

The minimum initial dilutions at the point of reaching the seabed layer for three discharge options are summarised in Table 3.

Table 3. Initial physical dilution of heat exchange cold-water discharge Water depth below Single port discharge Double port discharge Six-port discharge discharge point (AGL Preferred design) High tide depth 12.2 m 10:1 12:1 23:1 Low tide depth 9.2 m 8:1 10:1 20:1 Discharge rate = 450,000 kL/d /d; FSRU fully loaded

The time for the cold-water plume to leave the discharge point and reach the seabed at low tidal current speeds is less than one minute (approximately 20 seconds) as shown in CEE 2018a and 2018b. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 21

The results from the chlorine chemical reduction experiments for the second phase (start is 4 minutes after initial mixing) with second phase starting concentration 0.5 mg/L are shown in Figure 11.

100% 90% 80% 70% 60%

50% 12°IC=0.5 40% 16°IC=0.5 30% 20% 20°IC=0.5 10% ecn hoieeann,Co = chlorineremaining, Percent 4 min 0% 0 10 20 30 40 50 60 Time, min

Figure 11. Percent chlorine reduction in second phase from starting concentration 0.5 mg/L

The figure shows that the chemical reduction rate of free chlorine concentration over the first five minutes is very slow at 12°C (<2%) compared to 16°C (15%) and 20°C (16%). Hence the total physical dilution and chemical reaction in chlorine concentration over the initial dilution stage of discharge dispersion is: · Entirely (>99.9%) due to the physical process of initial dilution alone at 12°C with no reduction from chemical reaction; · 99% due to the physical process of initial dilution at 16°C and 20°C, with only about another 1% reduction due to chemical reaction.

The net concentration of chlorine in the cold-water discharge over the initial dilution stage due to initial dilution and chemical reduction for the discharge close to the seabed is shown in Table 4. At this stage, chlorine concentrations may be above the ANZECC Guideline value (Table 1), and further reduction of chlorine concentration by physical and chemical processes is required to ensure environmentally safe levels of chlorine are maintained in North Arm (see Sections 5.3, 5.4 and 7.2 below).

Table 4. Chlorine concentration after initial dilution and 20 second chemical reaction Discharge arrangement Water temperature 12°C 16°C 20°C

One outlets 0.011 mg Cl2/L 0.011 mg Cl2/L 0.011 mg Cl2/L

Two outlets 0.009 mg Cl2/ 0.009 mg Cl2/ 0.009 mg Cl2/ Six-port discharge 0.005 mg Cl2/L 0.005 mg Cl2/L 0.005 mg Cl2/L (AGL preferred design) AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 22

5.3 Nearfield phase (6 hours) The nearfield phase of the dispersion in this example may be considered to be one ebb or one flood tidal excursion over a period of approximately 6 hours. The results from the chlorine experiments for the second and third phase (start is 4 minutes after initial mixing and showing results for first 6 hours) with second phase starting concentration 0.5 mg/L are shown in Figure 12.

100% 12°IC=0.5

90% 16°IC=0.5 80% 20°IC=0.5 70% 60% 50% 40% 30% 20% 10% Percent chlorineremaining,Co= 4 min 0% 0 60 120 180 240 300 360 Time, min Figure 12. Percent chlorine reduction in second and third phase Starting concentration 0.5 mg/L

The figure shows that the reduction rate due to chemical reaction in seawater over the first 6 hours ranges from almost 40 percent for 12°C seawater to almost 70 percent in 16°C and 20°C seawater. The variation in chlorine concentration measurement at 16°C and 20°C in the first hour demonstrates the difficulties associated with the rapid speed of the chemical reactions versus the relatively slow speed of the analytical methods. However, the results are generally consistent with the published data discussed previously and are suitable for the purposes of this assessment. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 23

5.4 Net outcome of chemical reduction and physical dilution The net reduction in percent chlorine over a six-hour period due to initial dilution and chemical reaction and not allowing for nearfield mixing is shown in Table 5 and the corresponding chlorine concentrations are shown in Table 6.

Table 5. Net remaining chlorine after initial dilution and 6 hours chemical reaction Discharge arrangement Water temperature 12°C 16 to 18°C One outlet 7.8 % 3.3 % Two outlets 6.4% 2.2 Six-port discharge 3.3% 1.4 % (AGL preferred design)

Table 6. Chlorine concentration after initial dilution and 6 hours chemical reaction Discharge arrangement Water temperature 12°C 16 to 18°C

One outlet 0.008 mg Cl2/L 0.003 mg Cl2/L

Two outlets 0.006 mg Cl2/L 0.003 mg Cl2/L Six-port discharge 0.003 mg Cl2/L 0.001 mg Cl2/L (AGL preferred design)

The estimates at this stage are relatively conservative due to the likelihood of increased chemical reduction rates of chlorine at the lower concentrations resulting from physical dilution. A permanent cold-water layer is not expected to form from the preferred six-port discharge design with relatively high subsequent mixing and dilution, and chlorine concentrations less than 0.001 mg/L 200 m downstream of the discharge outlets at mean seawater temperature. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 24

6 ECOTOXICITY TEST OF CHLORINE IN CRIB POINT SEAWATER As discussed in previous sections of this report, the concentration of chlorine reduces over three time phases starting immediately after its mixing with seawater. Regulators recognise this characteristic in setting indicative chlorine concentration protection levels and procedures for monitoring chlorine in the environment.

The rate of chlorine reduction in seawater depends on local seawater characteristics: the concentration of inorganic constituents that react rapidly with chlorine; the concentration of organic constituents that react rapidly with chlorine; the concentration of inorganic and organic constituents that react at slower rates with chlorine and bromine, and; ambient temperature.

The toxicity of residual reactive chlorine constituents to the plants and animals in the marine ecosystem also depends on the sensitivity of the local marine pants and animals to chlorine concentration. The difficulty in establishing safe ecosystem levels for chlorine in seawater ecosystems is discussed in Section 3 above.

Toxicity tests on at least five and up to 12 species are needed to establish environmentally safe dilutions for chemicals (Warne et al 2015), and it is likely that the USEPA and ANZEECC ecosystem protection guidance values presented in Section 3 are based on a sufficient range of quality assured data. However, the data are likely to have included overseas species and these limitations are recognised in the USEPA and ANZECC documents. It was considered useful, therefore, to test the sub-acute toxicity of chlorine in Crib Point seawater using a relevant southeastern Australia species and recognised test procedure to inform discussion of potential toxicity issues associated with the residual chlorine concentration in the seawater discharge at Crib Point and comparison with the USEPA and ANZECC guidance values.

6.1 Sub-acute sea urchin fertilisation 1-hour ecotoxicity test A short term ecotoxicity test was chosen to inform assessment of the potential toxicity of the seawater heat exchanger discharge over the initial stage of dispersion in the marine environment at Crib Point. Ecotoxicity Services Australasia Pty Ltd is NATA accredited for a range of marine ecotoxicity tests including the sub-acute sea urchin fertilisation 1-hour ecotoxicity test (Figure 14).

The test followed a standard, nationally accredited procedure that involves exposing sea urchin sperm and eggs to a range concentrations of test material (chlorine-in-seawater) for one hour and twenty minutes. At the end of the exposure the percentage of fertilised eggs is determined. Statistical analyses are then applied to the results including the control exposure data to estimate the concentrations of chlorine causing chronic toxicity to a representative sensitive species reproductive stage.

The test gametes used were from the sea urchin Heliocidaris tuberculata, which is closely related to Heliocidaris erythrogramma (Figure 13) that is found together with Goniocidaris tubaria under Crib Point jetty. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 25

Figure 13. Sea urchin Heliocidaris erythrogramma under Crib Point jetty

Figure 14. Fact sheet for sea urchin fertilisation toxicity test AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 26

6.2 Sea urchin fertilisation test conditions The standard test conditions for the sea urchin fertilisation test are described in Ecotox Services Test Report TR1518/2. Modifications for the chlorine toxicity test are discussed below.

6.2.1 Test temperature It was recognised: 1. that average winter seawater temperature at Crib Point is approximately 12°C and chlorine concentrations are expected to remain higher in the mixing area at lower temperature 2. but that the test organism does not reliably produce gametes at temperature lower than 16°C. Many species do not reproduce in winter and gametes are expected to be low in abundance at lower water winter temperatures compared to warmer spring and summer water temperatures.

Therefore, toxicity was tested at 16°C as the average water temperature at Crib Point rather than the standard 20°C test temperature or at colder temperatures that may occur at Crib Point.

6.2.2 Test concentration range The results of the chlorine reduction trials, the regulatory safe limits, the concentration of chlorine in the FSRU discharge and the statistical basis for were considered in setting the six nominal concentrations (as ‘mg free Cl2/L’) to be used in the tests.

It was recognised that most of these concentrations would be estimated by serial dilution of the initial stock concentration and that actual commencement concentrations may vary due to the reduction processes described above. Hence, Ecotox Services reports results in three forms: 1. Percentage dilution – the dilution factor of the stock concentration 2. Nominal concentration – the concentration estimated from the dilution of the initial stock chemical concentration 3. Measured concentration – the concentration measured at the commencement of the test

The nominal concentrations and corresponding percentage dilution factor based on a stock concentration of 2 mg freeCl2/L used in the tests and resulting measured concentration are shown in Table 7.

Table 7. Chlorine concentrations used in toxicity test Nominal Dilution percentage Measured mg freeCl2/L 2 mg freeCl2/L stock mg freeCl2/L 2.0 100 2.021 1.0 50 0.954 0.5 25 0.456 0.1 5 0.081 0.05 2.5 0.038 0.01 0.5 0.021 AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 27

6.3 Toxicity test results The concentration at which responses occur after the test duration are recorded relative to control waters. The responses are: 1. the lowest concentration at which a response occurred that was statistically significantly different from the control preparation is referred to as the LOEC; and 2. the concentration at which no response occurred is referred to as the NOEC.

If the NOEC is less than 100% effluent, then a statistical interpolation is used to determine the effluent concentration at which 50 percent of the test organisms were affected. This concentration is known as the EC50 (effect concentration at which 50% of organisms responded). The EC50 allows a comparison of the results on a continuous concentration scale of, rather than the incremental results of NOEC and LOEC that can only be expressed in terms of the concentrations using in the test, which in this case were 2 mg/L; 1 mg/L; 0.5 mg/L; 0.1 mg/L; 0.05 mg/L; 0.01 mg/L. Hence, higher EC50s represent lower effluent toxicity.

An IC10 can also be statistically determined, which represents the calculated concentration at which 10 percent of the test biota are affected by the test exposure.

The EC50 or IC50 can be converted to Toxicity Units (TU) by simply calculating the reciprocal of the EC50. Hence, higher values on the TU scale represent higher toxicity of effluent, with 1 TU representing the lowest toxicity.

The toxicity test outcomes are shown graphically in Figure 15. Statistical analysis outcomes are summarised in Table 8.

Figure 15. Graphical results of ecotoxicity test (Measured concentration) AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 28

Table 8. Statistically calculated outcomes of toxicity test (Measured concentration) Outcome Chlorine concentration,

mg freeCl2 /L IC10 0.059 EC50 0.133 NOEC 0.038 LOEC 0.081

6.4 Interpretation of ecotoxicity test results Figure 15 and Table 8 show that: · There was no fertilisation success at a concentration of 0.465 mg/L free chlorine in Crib Point seawater relative to the control treatment (plain filtered seawater) · Fertilisation of 50 percent of eggs in a concentration of 0.133 mg/L free chlorine was unsuccessful relative to the control treatment (plain filtered seawater) · Fertilisation of 10 percent of eggs in a concentration of 0.059 mg/L free chlorine was unsuccessful relative to the control treatment (plain filtered seawater) · Fertilisation of sea urchin eggs was unaffected by a concentration of 0.038 mg/L free chlorine in seawater.

6.5 Comparison with Guidance values As discussed above, the result of a single toxicity test is insufficient to determine the environmentally safe concentration for a chemical, but the test using a southeastern Australian sea urchin species provides regional context to the guidance values established using data from national and international sources. The NOEC of 0.038 mg Cl2/L and IC10 value of 0.059 Cl2 mg/L are higher than the ANZECC 2000 indicative interim working value of 0.003 Cl2 mg/L. This indicates that ANZECC 2000 indicative interim working value is greater than a factor of 10 to 20 below the NOEC and IC10 and is an appropriate conservative and useful value: · “for modelling purposes and for making decisions concerning this particular application… (heat exchangers)” (USEPA), and · “as an indicative interim working value” (ANZECC 2000) for this stage of the Project.

It is likely that the results of additional chlorine bioassays have been published since the database used to establish the USEPA and ANZECC 2000 guidance values, and that different regulatory toxicity values may become available in the future. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 29

7 CONCLUSION

7.1 Implication of chlorine reduction and toxicity tests for Crib Point results Chlorine concentration modelling in the feasibility stage of the Project included the first rapid stage of chlorine reduction in modelling the discharge and subsequent dispersion in the environment. This may have overestimated chlorine reduction in the environment and underestimated chlorine concentration in the environment.

The implications of subsequent chlorine reduction trials and the toxicity tests using (1) Crib Point seawater (2) a sub-acute (chronic) test sensitive (3) a representative marine species and (4) a test temperature relevant to the Crib Point environment and ecosystem are: · The concentration of 0.5 mg/L of free chlorine generated at the entrance to the seawater heat exchange system will be toxic to a range of marine organisms passing through the heat exchange system. This is the desired outcome for the operation of the heat exchange system. · The concentration of 0.1 mg/L of free chlorine remaining in the seawater as it leaves the heat exchange system will be toxic to some marine organisms that are very close to the discharge point and that are exposed for long enough for a toxic effect to occur. This is a generally accepted localised outcome for the operation of the heat exchange system provided that the effect is localised. · The toxicity test NOEC of 0.038 mg/L of free chlorine is higher than the USEPA and ANZECC safe concentrations (Table 1) for free chlorine. o This is expected for a single species test, and demonstrates that the USEPA and ANZECC safe concentrations (Table 9) are appropriately conservative and useful: § “for modelling purposes and for making decisions concerning this particular application… (heat exchangers)” (USEPA) § “as an indicative interim working value” (ANZECC) for this Project. · It is likely that the results of additional chlorine bioassays have been published since the database used to establish the USEPA and ANZECC 2000 guidance values, and that different regulatory toxicity values may become available in the future.

7.2 Synthesis of factors affecting chlorine concentration targets for Project Table 9 presents the regulatory guidance safe concentrations of free chlorine (from Table 1), together with the calculated free chlorine concentrations calculated at 16°C (representing median ambient seawater temperature at Crib Point) after the period of initial dilution (from Table 4) and chemical reduction after 6 hours (from Table 6). AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 30

Table 9. Compiled environmental guidance and project chlorine concentrations

Condition Free chlorine, mg Cl2/L ANZECC 2000 (95% SP) 0.003 USEPA (4 day) 0.0075 USEPA (1 hour) 0.013 At Discharge 0.1 After initial dilution and 20 sec chemical reduction: One and two port discharge 0.011 Six-port discharge 0.005 After initial dilution and 6 hours chemical reduction: One and two port discharge 0.003 Six-port discharge 0.001

The evidence concludes that: · The process of initial dilution from the six-port discharge port/s will reduce the concentration of free chlorine residual from 0.1 mg Cl2/L at the outlet to 0.005 Cl2/L at the seabed. Further mixing with tidal currents within 200 m of the discharge point will reduce the chlorine concentration in seawater at ambient temperature of 12°C is to 0.003 Cl2/L within 200 m downstream of the discharge point, while in warmer seawater (16°C to 18°C) the chlorine concentration is estimated to reduce to 0.001 mg Cl2/L within the same distance. · Discharge of the seawater via a six-port discharge, in accordance with AGL’s preferred design, is expected to reach environmentally safe concentrations within an area extending approximately 200 m downstream of the discharge (north during rising tide and south during lowering tide) and 60 m east and west, based on the existing model outputs and regulatory guidance values for chlorine toxicity. AGL Gas Import Jetty Project – Chlorine in seawater heat exchange process 31

8 REFERENCES ANZECC 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Burton 1977. General test conditions and procedures for chlorine toxicity tests with estuarine and marine macroinvertebrates and fish. Chesapeake Science March 1977, Volume 18, Issue 1, pp 130–136. CEE 2018a. Plume Modelling of Discharge from LNG Facility at Crib Point, Western Port – AGL Gas Import Jetty Project. Report for AGL. Report for AGL. CEE 2018b. Assessment of effects of cold-water discharge on marine ecosystem at Crib Point – AGL Gas Import Jetty Project. Report for AGL. Saeed Suhur, Shwet Prakash, Nandita Deb, Ross Campbell, Venkat Kolluru, Eric Febbo and Jennifer Dupont 2015. Development of a Site-Specific Kinetic Model for Chlorine Decayand the Formation of Chlorination By-Products in Seawater. Journal of Marine Science and Engineering 2015 3:772-792 SOEQ (State of Oregon Environmental Quality) 2014. Implementation instructions for the Water Quality Criterion Chlorine (CAS#7782-50-5). Memorandum 28 November 2014. USEPA 1985. Ambient Water Quality Criteria for Chlorine -1984. EPA 440/5-84-030 January 1985. US Environmental Protection Agency. USEPA 1991. Aquatic Life Fact Sheet – Ambient Water Quality Value- Substance: CHLORINE (Total Residual). Fact Sheet Date: Sep 1 1991” USEPA 2017. Operating Procedure. Field Screening of Total Residual Chlorine. Region 4. U S Environmental Protection Agency. Science and Ecosystem Division. Athens, Georgia. Wahab 2012: Environmental Impact Assessment of Residual Chlorine Discharge into Seawater. Presentation Chemical Engineering Program, Texas A&M University at Qatar, May 2012. Wang Jih-Terng, Ming-Hui Chen, Hung-Jen Lee, Wen-Been Chang, Chung-Chi Chen, Su- Cheng Pai and Pei-Jie Meng. 2008. A model to predict Total Chlorine Residue in Cooliong Seawater of a Power Plant Using Iodine Colorimetric Method. International Journal of Molecular Sciences 2008 (9): 542 – 553. Warne MStJ, Batley GE, van Dam RA, Chapman JC, Fox DR, Hickey CW and Stauber JL. 2015. Revised Method for Deriving Australian and New Zealand Water Quality Guideline Values for Toxicants. Prepared for the Council of Australian Government’s Standing Council on Environment and Water (SCEW). Department of Science, Information Technology and Innovation, Brisbane, Queensland. 43 pp. Water Technology 2017. Hydrodynamic & Water Quality Modelling, Western Port Bay. Report to AGL Wholesale Gas Ltd. Zeng Jiangning, Jiang Zhibing, Chen Quanzhen, Zheng Ping, Huang Yij 2009. The decay kinetics of residual chlorine in cooling seawater simulation experiments. Acta Oceanologica Sinica 2009, Vol.28, No.2, p.54- 59.

Attachment 7

Report to: Jacobs Group (Australia) Pty Ltd

AGL Gas Import Jetty Project Crib Point, Western Port

Assessment of effects of cold-water discharge on marine ecosystem

FINAL

30 August 2018 AGL Gas Import Jetty Project Crib Point, Western Port

Assessment of effects of cold-water discharge on marine ecosystem

Contents EXECUTIVE SUMMARY 1 1 Introduction 3 1.1 Project overview 3 1.2 Purpose of this report 3 2 Heat Exchange Discharge model 4 2.1 Factors affecting formation of a cold-water plume on seabed 5 2.2 Key outputs of plume modelling 6 2.3 Environmental syntheses of discharge model outputs 7 2.3.1 AGL preferred option: six-port discharge 9 2.3.2 Recommended Baseline Monitoring 9 3 Marine ecosystem assessment 10 3.1 Extent of possible effect on marine ecosystem 11 3.2 Marine communities potentially affected 13 3.2.1 Infauna 13 3.2.2 Epifauna 17 3.3 Ecosystem temperature exposure 20 3.3.1 Review and monitoring of temperature variation 20 4 Conclusion 21 5 References 23

Figures Figure 1. Natural marine ecosystem components at Crib Point 4 Figure 2. Behaviour of cold-water discharge from FSRU at Crib Point 5 Figure 3. Maximum horizontal extent of cold-water fields (concept) 7 Figure 4. Maximum extent of cool water field cross-section (concept) 8 Figure 5. Detailed bathymetry at Crib Point Jetty head 8 Figure 6. Natural marine ecosystem components at Crib Point 10 Figure 7. Conceptual model of Western Port marine ecosystem in Crib Point area 11 Figure 8. Marine characteristics and extent of temperature difference on seabed 12 Figure 9. Infauna sampling strata and sites - Westernport Bay Environmental Study 14 Figure 10. Distribution of ghost shrimp Calliax tooradin 15 Figure 11. Distribution of ghost shrimp Michelea microphylla 16 Figure 12. Seabed epibiota on channel bottom near Bluescope 17 Figure 13. Seabed and epibiota under Crib Point Jetty, Berth 1 18 Figure 14. Seapens in lower North Arm 18 Figure 15. Seabed in shipping basin at jetty edge, Berth 1 (northern), Crib Point 18 Figure 16. Biota under Stony Point jetty 19 Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem

Report to Report prepared by Scott Chidgey CEE Pty Ltd Unit 4, 150 Chesterville Rd Cheltenham, VIC, 3192 Ph. 03 9553 4787 Email. [email protected]

Cover photo: Crib Point Jetty (S Chidgey)

Document History

Document Details Job Name AGL Gas Import Jetty Project Job No. IS210700 Document Assessment of effects of cold-water discharge on marine ecosystem File Ref Revision History Revision Date Prepared Checked Approved by By By Final (Ver 01) 19/07/18 Name S Chidgey S Ada S Ada

Final (Ver 02) 30/08/18 Name S Chidgey S Ada S Ada AGL Gas Import Jetty Project Assessment of effects of cold-water discharge on marine ecosystem at Crib Point

EXECUTIVE SUMMARY AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

The FSRU will be continuously moored to receive LNG cargos from visiting LNG carriers, store the LNG and re-gasify it as required to meet demand for high pressure pipeline natural gas.

Regasification involves the heating of the -162oC liquefied gas using the ambient heat of seawater in Western Port. A daily volume up to 450,000 m3 (450 ML/d) (when operating at full capacity) of seawater from Western Port will be pumped at a rate of 5.2 m3/s through heat exchangers in the FSRU. The discharged seawater temperature will be 7oC lower than ambient temperature at Crib Point.

AGL engaged Jacobs Group (Australia) Pty Ltd (Jacobs) and their specialist subconsultants to investigate the potential impacts of the seawater intake/discharge arrangements on environmental conditions in Western Port. A series of desktop studies have been undertaken to investigate the hydrodynamics of Western Port and the ecological effects of the seawater intake, the discharge of cooler seawater and the discharge of anti-fouling compounds. The purpose of this report is to examine the effects of the cold-water discharge from the FRSU on the marine ecosystem. The report integrates the near and mid-field hydrodynamic modelling outputs with the existing information on ecosystem characteristics and provides guidance on the impact pathways and extent of effect of the cold-water plume on the marine environment.

This report has been prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), · A referral under the Victorian Environment Effects Act 1978, and · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act).

The behaviour of the cold-water discharge plume was modelled by CEE (2018) using known and quantified physical fluid dynamics processes, the characteristics of seawater in North Arm of Western Port and tidal current characteristics at Crib Point. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 2

The cold-water discharged from the FSRU heat exchanger will initially be 7oC cooler than ambient but within seconds, the descending plume will be close to the seabed and will have mixed with sufficient surrounding seawater to reduce the temperature.

Relevant information on the nature and distribution of marine ecosystem components in the vicinity of the FSRU was compiled from a range of existing information sources. The modelled behaviour of the discharge showed that the cold-water rapidly descended to depths greater than 12.5 m below the sea surface and demonstrated that marine ecosystem components in water depth less than approximately 12.5 m water depth would not be directly affected in the case of either a single-port or six-port discharge. Consequently, it is concluded that saltmarsh, mangrove, mudflat, intertidal seagrass, subtidal seagrass and channel slope communities and sensitive species that occupy habitats to a water depth of 12.5 m will be unaffected by the direct effects of the cold-water discharge. Hence, a substantial proportion of marine ecosystem habitats and communities will be separated from the effects of cold-water by the physical behaviour of the cold-water discharge.

Species that occupy habitats in water depths greater than 12.5 m in the vicinity of the discharge may be exposed to water temperatures a maximum 0.3°C cooler than ambient within 200 m of the discharge for the preferred six-port discharge. Modelling showed that the extent of the cold-water will depend on a range of tidal and discharge conditions. A single- port discharge temperature differential may extend a maximum of 600 m downstream of the discharge with a maximum width of 240 m, and the cold-water may form a pool on the seabed at low tide during periods of particularly low currents. AGL has adopted a six-port discharge with a resulting temperature differential that reaches within 0.3°C of ambient at a maximum of 200 m downstream of the discharge point with a maximum width of 60 m either side of the discharge. A stable cold-water pool never forms for the six-port discharge. The only location that will be constantly exposed to cool seawater will be the water column and seabed within the fall line of the descending cool plume next to the FSRU.

The biota occupying habitats in water depths greater than 12.5 m depth include the benthic invertebrate fauna that live in (infauna) or on (epibiota) the soft seabed of the channel planktonic plants and animals (phytoplankton and zooplankton) that drift in the tidal currents and fish that swim along the seabed in the deeper parts of the North Arm channel. There are no seagrasses in this area due to insufficient natural light for seagrass photosynthesis. These biota within 200 m upstream and downstream of the discharge and 60 m either side of the discharge may be affected by exposure to cold-water. Exposure of benthic invertebrate community to cold-water will be intermittent as reversals in tidal currents carry the waters up and down the channel. Mobile species in the area may be exposed over a shorter period and may avoid the cooler water by moving higher in the water column or around the water body if affected.

The location with highest exposure to the cold-water discharge will be the seabed in the shipping basin directly beneath the discharge. This will be the location where effect of the discharge on the marine ecosystem is likely to be greatest. Initial dilution and nearfield modelling suggest that the water temperature differential of the discharged seawater of 7°C below ambient at the point of discharge will reduce to 0.8°C below ambient near the seabed for a single-port discharge and 0.3°C below ambient near the seabed for a six-port discharge. The effect of the discharge from the AGL preferred a six -port discharge is unlikely to be detectable at 200 m from the FSRU six-port discharge. .

AGL will undertake additional studies to further define the effects within North Arm and to document the distributions of marine ecosystem components in the vicinity of the discharge, which were previously systematically documented more than 40 years ago. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 3

1 INTRODUCTION 1.1 Project overview AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

Jacobs Group (Australia) Pty Ltd (Jacobs) was engaged by AGL to undertake planning and environmental assessments for the AGL Gas Import Jetty Project. Jacobs engaged CEE Environmental Scientists and Engineers to define the marine environmental characteristics and identify key potential risks to the marine environment from the development and operation of the Project.

1.2 Purpose of this report This report integrates the near and mid-field modelling outputs as documented in the report ‘Plume Modelling of Discharge from Floating Storage and Regasification Unit’ (CEE 2018a) with the existing information on ecosystem characteristics and provides guidance on the impact pathways and extent of effect of the cold-water plume on the marine environment.

This report has been prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), · A referral under the Victorian Environment Effects Act 1978, · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act). Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 4

2 HEAT EXCHANGE DISCHARGE MODEL The FSRU will be located at the southern end of Crib Point Jetty, in the shipping basin approximately 500 m offshore from the inshore seagrass beds (Figure 1). Cool seawater from the FSRU heat exchanger will be discharged to the main channel of North Arm.

Figure 1. Natural marine ecosystem components at Crib Point (Position of FSRU shown in red)

The behaviour of the cold-water discharge from the FSRU is discussed in CEE’s ‘Plume Modelling of Discharge from Floating Storage and Regasification Unit (2018a). The general behaviour of the cold-water discharge from the FSRU is shown in Figure 2. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 5

Figure 2. Behaviour of cold-water discharge from FSRU at Crib Point (showing a single point discharge for simplicity, CEE 2018a)

The plume of water starts from the discharge ports on the FSRU and discharges at 7°C cooler than the adjacent seawater and is therefore more than 1 kg/m3 more dense than ambient seawater.

The plume descends to the seabed, diluting on the way due to shear between the descending plume and the adjacent seawater. The initial dilution during the descent increases marginally at times of stronger tidal current. During periods of relatively low tidal currents, the cold-water plume reaches the seabed and spreads over the seabed in the shipping basin.

The cold-water layer is denser than the surrounding ambient seawater and, in the absence of strong tidal currents may form a pool that tends to move with weak tidal currents and downhill, with the thickness above the seabed getting smaller as the pool spreads. Stronger tidal currents push along the surface of the cold-water pool and further erode the thickness of the cold-water layer.

2.1 Factors affecting formation of a cold-water plume on seabed Modelling (CEE 2018a) included consideration of the following factors that affect the temperature, thickness, extent and stability of the plume: · Number of discharge ports o one and two port outlet options were modelled as a conservative case, with a six-port option to demonstrate the effect of increased dilution through a multiport discharge · Angle of discharge ports o Three angles modelled · Depth of water o Variable 1 = tidal range at Crib Point, Variable 2 = draft of vessel at different loads · Discharge rate o Initial dilution for three flows was modelled: 150,000 kL/day; 300,000 kL/day; 450,000 kL/day · Bathymetry Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 6

o dredged basin, natural slopes and features outside dredged basin · Tidal current strength o Tidal current strength has only a minor effect on the initial dilution of the cold-water plume as the plume descends toward the seabed, but considerably effects the thickness, spatial extent and duration of cold-water layer on the seabed o Initial dilution was modelled at slack water o Layer formation and stability was modelled over an average flood tide (rising tide and currents travelling northward).

2.2 Key outputs of plume modelling The key outputs of plume modelling from CEE (2018) are: · Initial dilution of a 450,000 kL/day (5.2 m3/s) discharge through o Single outlet at slack water resulted in a dilution at the seabed of: o 8:1 at low water and 10:1 at high water o Dual-port outlet at slack water resulted in a dilution at the seabed of: o 10:1 at low water and 12:1 at high water o Four-port outlet at slack water resulted in a dilution at the seabed of: o 15:1 at low water and 17:1 at high water o Six-port outlet at slack water resulted in a dilution at the seabed of: o 20:1 at low water 23:1 at high water

· The corresponding difference in temperature between the cold-water field on the seabed and the surrounding ambient seawater at high tide would be: o -0.8°C for the single port discharge o -0.7°C for the dual port discharge and o -0.45°C for the four-port discharge and o -0.3°C for six port discharge.

· The field from the single discharge will form a stable pool of cool water on the seabed at currents speeds less than 0.13 m/s for approximately 1 hour either side of the turn of the tide. The stable pool of cold-water (up to 0.8oC below ambient) will intermittently form and extend: o north of the discharge point during flood tides and south during ebb tides o up to 900 m from the discharge point depending on tide height and ambient currents o 250 m east and west of the discharge point.

· The field from a six-port discharge could occasionally form a temporary, unstable cold- water layer (up to 0.3°C below ambient) within approximately 200 m of the discharge at slack water during some low tides. More ports than six will produce greater initial dilution and smaller temperature differentials at the seabed.

· Cold-water plumes from all options modelled (one outlet to six-port outlet) will descend to the seabed with sufficient momentum to form a detectable local depression in the seabed. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 7

2.3 Environmental syntheses of discharge model outputs Figure 3 and Figure 4 show the maximum extent of the cold-water plumes for one port and six port discharge options based on the model outputs, which assume a relatively flat seabed in the area of the pool.

Figure 3. Maximum horizontal extent of cold-water fields (concept) One outlet and six-port discharge port options Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 8

0 0 200 400 600 800 1000 Distance from high tide mark, m -5

1 discharge port -10 6 discharge ports

-15 Water depth to LAT, m

-20 Figure 4. Maximum extent of cool water field cross-section (concept) One outlet and six-port discharge port options

Figure 5 shows that, while the seabed is relatively flat, there are gentle variations of 1 m to 2 m that are likely to affect the shape of the cold-water pool as it spreads beyond the footprint of the descending plume.

Figure 5. Detailed bathymetry at Crib Point Jetty head

The models for the one-port discharge and the six-port discharge demonstrate the consequences of discharge configuration on plume characteristics and the potential extent of environmental effect. Increasing the number of discharge ports at appropriate spacing increases the mixing rate of the cold-water and reduces the temperature differential between the cold-water plume and the surrounding ambient seawater. More than six ports would produce greater initial dilution and smaller temperature differentials at the seabed. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 9

Monthly seawater temperature measurement at EPA water quality monitoring site 709 located in the main channel approximately 2 km north of Crib Point typically ranges between 11°C and 22°C over the year. Water temperature measured at Long Island Point in March 2016 varied naturally by 0.3°C over a 4-hour period (CEE data). Hence a 0.3°C temperature difference over a relatively small area appears within the range of short term-natural variation.

Further assessment of short-term and long-term variations in seawater temperature at Crib Point would provide further context for assessment of the effect of temperature differentials resulting from the heat exchanger seawater discharge on marine ecosystem components in the temperature differential footprint.

2.3.1 AGL preferred option: six-port discharge The AGL preferred design for discharge of the cold seawater is through a six-port discharge arrangement, instead of the alternate single (or double) discharge port/s. This optimises dilution of the discharge and results in a smaller temperature difference closer to the discharge point being an area approximately 200 m north and south and 60 m east and west of the discharge point, representing a total seabed area of approximately 5 ha. No cold-water pool is expected to form on the seabed at any stage of the tide with the six-port discharge.

2.3.2 Recommended Baseline Monitoring Seawater temperature monitoring will document natural short-term variations in temperature and the actual extent of temperature differences and dispersion paths of the cold-water discharge. This will inform the potential effect of the cold-water discharge on the marine ecosystem of North Arm. Ambient monitoring at Crib Point in the next stage of assessment will further inform the understanding of the significance of the predicted temperature difference with natural short-term variations at different tides and seasons. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 10

3 MARINE ECOSYSTEM ASSESSMENT Western Port is a diverse but compact marine environment. It comprises vast intertidal mudflats with saltmarsh, seagrass and mangrove habitats as well as steep subtidal sloping banks with seagrass and deep channels that connect the north of the bay with the oceanic waters of Bass Strait in the south (CEE 1995, CEE 2009, EPA 1996, Melbourne Water 2011, Ministry for Conservation 1975).

The ecosystem components associated with the habitats are closely connected by their relatively close spatial proximity and the strong tidal currents that transport water back and forth through the channels and over and off the intertidal flats. The distribution of marine habitats in the vicinity of Crib Point Jetty is shown in Figure 6, and the marine communities associated with the habitats are shown in Figure 7.

Figure 6. Natural marine ecosystem components at Crib Point

The habitat distribution (Figure 6) and conceptual model of the marine ecosystem in the vicinity of Crib Point (Figure 7) show that the FSRU is at least 400 m from intertidal and nearshore marine ecosystem components. It is located in an area of the channel characterised by plankton and pelagic marine species in the water column and invertebrate species and demersal fish associated with the soft seabed around the jetty.

As discussed in Section 2.3, water temperature in North Arm varies seasonally from approximately 11°C to 22°C over the year and over tidal periods of hours as tides water cover the tidal flats and drain back into the cannels. Marine communities in the vicinity of Crib Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 11

Point are therefore accustomed to seasonal changes in seawater temperature. Natural seasonal patterns in seawater temperature combined with other seasonal queues such as day length, light intensity, salinity and tides are important factors affecting all marine ecosystem processes in Western Port.

Figure 7. Conceptual model of Western Port marine ecosystem in Crib Point area (Derived from CEE 2009)

The characteristics of the marine communities in Western Port were most recently described in Melbourne Water’s review “Understanding the Western Port Environment” in 2011. Much of the large-scale information on the distribution of invertebrates (see Section 3.2.1), fish and zooplankton in Western Port is based on systematic ecosystem sampling in the 1970s for the Western Port Bay Study (Coleman et al 1978, Ministry for Conservation 1975), more than 40 years ago. Seagrass distribution and limits have been studied more recently for the Port of Hastings Development Authority and a range of local scale monitoring programs and academic projects have investigated species or communities at a local scale. The outcomes of the cold-water plume dispersion modelling enable an assessment of potential effects of the cold-water discharge on targeted marine ecosystem components as discussed below.

3.1 Extent of possible effect on marine ecosystem As discussed previously, the cold-water from single/dual discharge ports from the FSRU would rapidly descend to the seabed and spread as discussed in the previous sections. Habitats in water depths less than 12.5 m deep will be unaffected by the discharge, except for those planktonic and pelagic species in direct contact with the descending cold-water discharge and those marine communities associated with the jetty piles within the trajectory of the descending cold-water discharge. The extent of possible effect of the cold-water discharge from one and six-port discharge options on marine communities in the Crib Point vicinity is shown in Figure 8. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 12

The figure indicates that effects of the cold-water discharge may occur on the soft seabed community of the channel (at water depths greater than 12.5 m), within the possible footprint of the intermittent, cooler-than-ambient field of water. The maximum temperature difference from ambient within this area may be 0.8°C for single or dual discharges, while it is less than 0.3°C for most of the area with a six-port discharge.

Figure 8. Marine characteristics and extent of temperature difference on seabed

Soft seabed communities on the steeper, western channel slopes will not be affected by the cold-water discharge. Subtidal seagrass, intertidal seagrass, intertidal mudflat, mangrove and saltmarsh communities will not be affected by the cold-water discharge. Planktonic and demersal communities close to the seabed may be exposed to small temperature differences during the time (<1 hour) they swim past or drift past the jetty with the tidal currents. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 13

3.2 Marine communities potentially affected The soft seabed communities within the cold-water footprint (Figure 8) are likely to comprise: · Infauna - sparse but diverse populations of invertebrates that live in the fine sandy, silty seabed of the channel floor, such as polychaetes, crustaceans and molluscs; · Epifauna - invertebrates that live on the surface of the seabed and; · Demersal fish - mobile fish that live on or close to the seabed.

3.2.1 Infauna Most of the area potentially affected by the cold-water footprint is soft seabed in the deeper channel area at water depth greater than 12.5 m. This habitat is characterised by the infauna community of burrowing invertebrates. This community was characterised during sampling for the Western Port Bay Study of 1973/74 (Coleman et al 1978). There has been localised sampling at some sites near jetties since then at BlueScope and Long Island Point, but no widespread surveys of the channel.

The infaunal communities in Western Port during the Western Port Bay Study were found to be highly species rich and abundant (Coleman et al 1978). The fauna was dominated by polychaete worms (the most numerous group), various crustaceans (the most species rich group) and molluscs (clams and snails).

The 1973/74 sampling process recognised a range of physical factors that might influence infauna community structure and divided the Bay into eleven different strata, of which the channel of North Arm was one entire stratum (Figure 9). The spatially comprehensive sampling program found that the most abundant species were widely spread. The errant polychaete worm Nepthys australiensis was the second most common species collected and was distributed over 85 percent of all stations sampled.

The characteristics of infaunal communities were divided into two general groups, in spite of the eleven different sampling strata. It was found that the key environmental factor that separated the two groups was sediment character. The two groups were termed (1) clean medium sand assemblage – with average mean grain size of medium sand and a mud content <10 percent, and (2) the fine sand and mud assemblage – with mud contents generally greater than 20 percent. These two groups appear to be correlated with depth: the first group being found in predominantly deeper channels and the second, muddier group, being found along the margins of the Bay. The infauna of the North Arm channel were part of the ‘clean medium sand assemblage’ along with channel and basin strata in the Corinella and Rhyll segments (Coleman et al 1978).

The clean medium sand assemblage was characterised by polychaete species Scoloplos, Rhodine, Travisa, clams Neotrigonia margaritacea, Notocallista diemensis, Solen vaginoides and Venericardia bimaculata, and crustaceans Halicarcinus rostratus Ampelisca Cheiriphotis megachelis Leptanthura diemensis and Paranchialina angusta.

The fine sand and mud assemblage was characterised by the polychaete worms Amaeana and Mediomastus and bivalve molluscs Tellina and Katelysia. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 14

Figure 9. Infauna sampling strata and sites - Westernport Bay Environmental Study (Source Coleman et al 1978)

Species diversity was marginally higher in the clean medium sand assemblage, although the difference was not statistically significant. In all strata, the order of taxonomic group abundance was polychaetes>crustaceans>molluscs, except for stratum 1 (North Arm channel) and stratum 6. Crustaceans were more numerous than polychaetes in North Arm channel.

The sample site in the Crib Point shipping basin was given particular mention from the 1973/74 sampling. The assemblage at the site was found to have very low diversity of polychaetes, crustaceans and molluscs, and very low abundance of polychaetes and molluscs. Only one crustacean species, Apseudes, was abundant. The low diversity and abundance of infauna at this site was attributed to ‘recent’ dredging (Coleman et al 1978).

The major finding of the infauna study was that the greatest influence on infauna characteristics was the composition of the seabed. Two major community groups were distinguished on this basis: ‘clean medium sand’; and ‘fine sand and mud’. Infauna at sites close to each with the same sediment character tended to be similar. The study concluded that the strongest similarities were between strata 5, 6, 8 and 10, which comprise fine to medium sediments in the east of the Bay. The next strongest similarities were between strata 1, 2 and 7: strata 1 and 2 comprise deeper sites in channels on both sides of the Bay; whereas stratum 7 represents shallow sites of medium to fine sediments in the east of the Bay. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 15

3.2.1.1 Potential Extent of Channel Infauna Community The area of potential effect from the cold-water discharge is located within stratum 1, which is an extensive area of approximately 70 km2 extending nearly 30 km from Sandy Point in south of North Arm to Bourchier Channel in the northeast (Figure 9). The maximum area of seabed that is potentially affected by the cold-water pool in the conservative one port discharge model is defined by the 0.7 km2 ellipse shown in Figure 8. In this case, the potential effect of the cold-water on infauna represents less than 1 % of the channel community of North Arm or 0.11% of Western Port. The installation of six-discharge ports on the FSRU will decrease the temperature difference to a maximum of -0.3°C from ambient within close proximity of the FSRU, which is likely to be within the range of natural local-scale seawater temperature variation in North Arm.

Figure 10. Distribution of ghost shrimp Calliax tooradin (O’Hara and Barmby 2000)

3.2.1.2 Potential Effect on Channel Infauna Species – species of concern The channel infauna community includes two species listed in the Flora and Fauna Guarantee Act. Both species are small ghost shrimps: Calliax tooradin (formerly Eucalliax tooradin) and Michelea microphylla. The burrowing clam Neotrigonia margaritacea is not listed but is known as a “living fossil” and therefore is a species of interest to some marine biologists.

The ghost shrimp Calliax tooradin is known only from a total of five individuals. Four were collected subtidally in grab samples offshore from Crib Point in 1965 and since then have not been recorded in Western Port (Figure 10). The habitat where it was found at Crib Point comprised fine sand in 5 m water depth. Its potential dependence on seagrass is not known, Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 16 but it has also been recorded from sediments among seagrasses at shallower depth in Swan Bay (Figure 10). Based on its depth range (5 m depth or less) from the few individuals collected, this species may be unlikely to be affected by the cold-water discharge due to the physically restricted depth range of the cold-water field (>12.5 m) and the relatively small temperature differential resulting from a multi-port discharge. There is some uncertainty in the actual depth range of this species due to the small number of records of this species.

The ghost shrimp Michelea microphylla is known from only one specimen collected in sandy gravel in 19 m water depth offshore from Crib Point in 1965 (Figure 11). It is very rare as it was not found in any other samples in the 1965 survey and has not been found in anywhere else since 1965, including the comprehensive infauna sampling program for the Western Port Study in the 1973/74 (Coleman et al 1978). The only known individual of this species was collected in depth range and location that may be affected by the cold-water discharge. The potential for impact (if any) on this species will be substantially reduced by the discharge of heat exchange seawater from the FSRU via a multi-port discharge arrangement.

Figure 11. Distribution of ghost shrimp Michelea microphylla (O’Hara and Barmby 2000) Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 17

3.2.1.3 Infauna baseline monitoring Infauna are the most representative ecosystem in the area of the cold-water pool footprint. It is more than 40 years since the infauna of North Arm, including the area that may be affected by the cold-water plume, have been documented. The characteristics of the infauna community in the channel area potentially affected by the cold-water field footprint is uncertain, but may include the FFG listed ghost shrimp Michelea microphylla and Calliax tooradin. The nature of the infauna community along the potential dispersion pathways and reference locations should be documented through an appropriately designed sampling program including: · Sediment characteristics; · Key infaunal community species abundance and distribution; · Targeted investigation of potential ghost shrimp Michelea microphylla and Calliax tooradin habitat.

3.2.2 Epifauna The distribution and abundance of large epibiota of the soft seabed, deeper channels in Western Port is not well documented. Inspections by CEE and other marine scientists over the years (e.g. J E Watson, Marine Science and Ecology, Figure 14) near BlueScope (Figure 12), Long Island Point Crib Point (Figure 13 and Figure 15) and Stoney Point indicate that the epibiota are sparsely distributed over much of the soft seabed or concentrated in high numbers or diverse ‘clumps’ at particular localities of favourable seabed conditions especially under jetties in North Arm.

Figure 12. Seabed epibiota on channel bottom near Bluescope (Seabed at all sites was relatively flat with no significant rock outcropping CEE 2008.)

Patches of coarse shell or rubbly material in channels provide relatively stable substrata for attachment and growth of sessile epifaunal animals (epizoic species) and associated mobile epifaunal animals. Sessile epizoic species include the brachiopod Magellania flavescens (Figure 13), the solitary ascidian Pyura stolonifera, sponges, hydroids and colonial ascidians (Smith et al. 1975). Magellania and the seapen Sarcophyllum can reach densities of 250 per m2 in suitable habitat, but is not thought to be common elsewhere in Bass Strait (Smith et al. 1975). Mobile epizoic species include the gastropod Sigapatella calyptraeformis, the sea stars Nectria ocellata, Patiriella brevispina and Tosia magnifica, and the urchin Goniocidaris tubaria (Figure 13) (Smith et al. 1975). Areas of firmer seabed may exist in the deeper channels that provide sufficient habitat for establishment of patches of sponge communities, while seapens such as Sarcophyllum and Sarcoptilus inhabit mobile sand waves as well as stable fine sand seabed (Figure 14). Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 18

Figure 13. Seabed and epibiota under Crib Point Jetty, Berth 1 Urchin Goniocidaris tubaria and seastar Nectria ocellata (left); cuttlefish and Magellania flavescens (right) (CEE November 2017)

Sarcophyllum sp Sarcoptilus grandis Figure 14. Seapens in lower North Arm (Photos J Watson May 2009)

Figure 15. Seabed in shipping basin at jetty edge, Berth 1 (northern), Crib Point (CEE November 2017) Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 19

Figure 16. Biota under Stony Point jetty Red hydroid (left); seastar Nectria oscellata (centre) solider crab Leptomithrax gaimardii (right) (March 2009 CEE)

3.2.2.1 Potential Effect on Channel Soft Seabed Epibiota Community The area of potential effect from the cold-water discharge is located within Stratum 1 of the natural seabed categories identified in the Western Port Bay Environmental Study, as discussed above (Figure 9). The maximum area of seabed and associated soft seabed epibiota that is potentially affected by the cold-water pool from a single-port discharge is defined by the 0.47 km2 ellipse shown in Figure 8. The area affected by a six-port discharge is substantially smaller as shown in Figure 8. Hence the potential effect of the cold-water represents less than 1 % of the soft seabed epibiota channel community of North Arm. As discussed above, this community has not been systematically surveyed, but is likely to be sparse, patchy and diverse.

3.2.2.2 Potential Effect on Channel Epibiota – biota of concern There are no listed threatened epibiota likely to occur in the area potential affected by the cold-water discharge. The various shipping jetties in North Arm, including Crib Point Jetty, provide an artificial habitat for relatively high numbers of biota from a range of interesting species as shown in the figures above.

3.2.2.3 Epibiota baseline monitoring Most species are thought to be distributed widely and populations are not likely to be directly threatened by the proposed discharge. However, there is no existing information on the distribution of epibiota in the shipping basin or channel around the jetty. Hence, a baseline investigation is required to confirm nature of epibenthic biological characteristics in the channel within approximately 1 km of the FSRU.

The most likely effect of the discharge of cold-water at Crib Point Berth 2 is likely to be detectable on the epibiota under the jetty at Berth 2 and less so at Berth 1. These biota are a potential indicator of the extent of the discharge effect on the wider ecosystem and it is recommended that these epibiota should be included in the environmental baseline program to document potential extent of effects of the project on the marine ecosystem of North Arm. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 20

3.3 Ecosystem temperature exposure The only location that will be constantly exposed to cool seawater from either a single-port or six-port discharge will be the water column and seabed within the fall line of the descending cool plume. The water temperature differential in the discharge plume will reduce from 7°C below ambient at the point of discharge to 0.8°C below ambient close to the seabed for the single port discharge and 0.3°C below ambient close to the seabed for the six-port discharge. As discussed in Section 2, the cold-water will then disperse to the north during flood tides and the south during ebb tides, resulting in a variable exposure to cold-water on the seabed along the dispersion pathways.

For the single-port discharge, cold-water at 0.8°C below ambient will spread along the seabed as an elongate pool for a possible distance up to 600 m north during the flood tide and south during the ebb tide, 60 minutes either side of the turn of the tide. Tidal currents during the middle 5 hours (approximately) of the tidal cycle will be sufficient to disperse the pool. The cycle will repeat approximately every twelve hours for both single and dual discharge options.

For a six-port discharge, the water column and seabed within the fall line of the descending cool plume will be the only location that will be constantly exposed to cool seawater. The cold-water plume will be 0.3°C below ambient and will disperse rapidly under most conditions without forming a layer on the seabed. A temporary pool up to 200 m long may form for less than an hour at some low tides if cross-currents are particularly weak. The pool is likely to be patchy due to the small temperature of the dilute cold-water discharge and natural variation in ambient seawater temperature.

The temperature exposure profile for positions along the cold-water dispersion pathways will be highly variable over time due to changes in initial dilution due to tide height and water depth below the discharge, reversals in tidal current direction, changes in tidal current speed over the tidal cycle, intermittent formation of the cold-water pool and the effect of seabed slope on the trajectory of the dispersion pathway at different current speeds.

3.3.1 Review and monitoring of temperature variation Biological activity and movement of many migratory fish species in Western Port tends to follow the increase in day length and water temperature in spring and through summer to early autumn. Hence, this is the period that small differences in temperature variation may affect migration of demersal fish species and biological processes such as spawning, growth and larval settlement of invertebrate species in the channel seabed community.

The effect of temperature variations on individual species is likely to vary substantially from species to species and also vary between biological processes within individual species. This is difficult to determine for the range of species in North Arm. However, the significance of the magnitude of temperature variations and the spatial extent predicted in the modelling so far do not appear sufficient to substantially affect populations of invertebrates in North Arm. The maximum temperature difference between the cold-water plume and ambient seawater after initial dilution is predicted to be 0.8°C for the single discharge option and 0.3°C for the six-port discharge option. Seawater temperature at Long Island Point can vary naturally by 0.3°C over a 4-hour period (as recorded in March 2016 by CEE). The effect of the cold-water is unlikely to be detectable at 600 m from the point of discharge.

The natural short term (daily to weekly) range of temperature variation should be investigated to provide context for assessing the potential proportional seawater temperature reduction due to the cold-water discharge from the FSRU. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 21

4 CONCLUSION The behaviour of the cold-water discharge plume was modelled using known and quantified physical fluid dynamics processes, the characteristics of seawater in North Arm of Western Port and tidal current characteristics at Crib Point. Data relating to the temperature of the discharge from the FSRU, the distance of the discharge below the water line and the daily flow of the FSRU were provided by AGL for the initial dilution and nearfield modelling tasks.

The cold-water discharged from the FSRU heat exchanger will initially be 7°C cooler than ambient (at the point of exit). In the conservative model using one or two port discharge from the FSRU, the cool seawater will leave the FSRU as a horizontal dense jet of water and mix with the surrounding, warmer seawater as it turns downward from horizontal and descends due to gravity in the warmer water column. Within seconds, the descending plume will be close to the seabed and will have mixed with sufficient surrounding seawater to reduce the temperature difference to 0.8°C cooler than the ambient seawater temperature. The cooler water will then disperse close to the seabed with tidal currents and gravity. The adoption of the six-port discharge will ensure that any temperature difference will be within ambient range within 200 m downstream of the FSRU discharge point.

Cold-water resulting from the discharge will only be present in the deeper channel of North Arm at water depth greater than 12.5 m. Hence all marine ecosystem components that are distributed at depths less than 12.5 m will be unaffected by direct contact with the cold-water.

Saltmarsh, mangrove, mudflat, intertidal seagrass, subtidal seagrass and channel slope communities and sensitive species that occupy habitats in water depth less than 12.5 m water depth will be unaffected by contact with the cooler water resulting from the heat exchange water discharge.

The biota that will have variable contact with the cold-water will be the invertebrates living on or in the soft sediments of the channel, the fish that may swim along the seabed and the animals that are found under the Crib Point Jetty. Mobile species in the area may be exposed over a shorter period and may avoid the cooler water by moving higher in the water column or around the water body if affected.

The invertebrate communities in the area that may be exposed to temperatures up to 0.8°C below ambient are thought to be widespread in North Arm. A maximum of 1 percent of the invertebrate community of the North Arm channel is expected to be exposed to temperatures up to 0.8°C below ambient for a single-port discharge and less than 0.3°C below ambient for a six-port discharge.

The only species of significance that is documented from the area that may be exposed to cooler water are ghost shrimp. The entire species of Michelea microphylla is known from one individual collected near Crib Point at 19 m water depth in 1965. No other individuals have been found anywhere since the first and only collection, including extensive studies in 1974/75 for the Western Port Bay Study. Calliax tooradin is known only from a total of five individuals. Four were collected subtidally in grab samples offshore from Crib Point in 1965 and since then have not been recorded in Western Port.

Initial dilution and nearfield modelling suggest that the water temperature differential of the discharged seawater of 7°C below ambient at the point of discharge will reduce to 0.8°C below ambient near the seabed for a single-port discharge and 0.3°C below ambient near the seabed for a six-port discharge. The effect of the discharge from a single-port discharge is unlikely to be detectable at 600 m from the FSRU and less than 200 m from the preferred six-port discharge. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 22

The only location that will be constantly exposed to cool seawater will be the water column and seabed within the fall line of the descending cool plume next to the FSRU. Almost all other areas will be unaffected. Overall, the impact to the surrounding marine ecosystem from the discharge of cooled water at 200 m from the FSRU is expected to be undetectable when operating using the preferred six-port discharge.

The characteristics of the invertebrate communities within in North Arm have not been documented for more than 40 years. Hence channel infauna and jetty epibiota baseline monitoring have been recommended to provide present-day context to refine the detail of ecosystem effects assessment. Victorian Regional Channels Authority (VRCA) intends to level 95 m2 of isolated high points at Berth 2 of Crib Point Jetty and engaged CEE to investigate the presence of threatened ghost shrimps in the vicinity of the high points in July 2018. No threatened species of ghost shrimp were found during the survey (CEE 2018b). A specific sampling program extending over a larger area of the seabed for ghost shrimp has been recommended for this Project.

Water temperature monitoring has been recommended to provide ambient context for assessment of the magnitude of natural short-term variation against the temperature differentials predicted by the initial dilution and near field models. Crib Point Gas Import Jetty Project –Assessment of cold-water effects on marine ecosystem 23

5 REFERENCES CEE 1995. A review of Western Port Marine Environment. Report to Environment Protection Authority Victoria by CEE Pty Ltd Consulting Environmental Engineers Richmond. CEE 2009. Port of Hastings Stage 1 Development. Marine Ecosystem. Preliminary Considerations. Report to AECOM and the Port of Hastings Corporation. CEE Consultants Pty Ltd, Richmond, Victoria. CEE 2018a Plume Modelling of Discharge from Floating Storage and Regasification Unit, AGL Gas Import Jetty Project. Report to Jacobs for AGL. CEE Pty Ltd, Cheltenham Victoria. CEE 2018b Threatened ghost shrimp survey Berth 2 Crib Point Jetty Risk from bed levelling of isolated high points. Report to VRCA, August 2018. Coleman N, W Cuff, M Drummond and JD Kudenov (1978). A quantitative survey of the macrobenthos of Western Port, Victoria. Australian Journal of Marine and Freshwater Research 29(4):445 - 466 EPA 1996. The Western Port Marine Environment. EPA Publication no 493. Environment Protection Authority Melbourne Water Corporation. (2011). Understanding the Western Port environment: a summary of current knowledge and priorities for future research. Melbourne Water, Melbourne. Ministry for Conservation (1975) Westernport Bay Environmental Study 1973-1974. Ministry for Conservation, Victoria. O’Hara T, Barmby V (2000) Victorian Marine Species of Conservation Concern: Molluscs, Echinoderms and Decapod Crustaceans. Parks, Flora and Fauna Division, Department of Natural Resources and Environment, East Melbourne, Australia.

Attachment 8

Report to: Jacobs Group (Australia) Pty Ltd

AGL Gas Import Jetty Project Crib Point Jetty, Western Port

Modelling and Assessment of Biological Entrainment into Seawater Heat Exchange System

FINAL

29 August 2018 AGL Gas Import Jetty Project Crib Point Jetty, Western Port

Modelling and Assessment of Biological Entrainment into Seawater Heat Exchange System

Contents

EXECUTIVE SUMMARY 1 1 Introduction 3 1.1 Project overview 3 1.2 Purpose of this report 3 2 Intake considerations 4 2.1 Intake design to minimise effects on marine biota 5 2.1.1 FSRU seaworthiness and engineering considerations 6 2.2 Position of intake in water column 6 2.3 Intake velocity – orientation and size of the intake 7 2.4 Intake grille and screens 9 2.5 Residual effect of intake on entrained biota 9 3 Hydrodynamics of Western Port 11 3.1 Net Water Movement 13 3.2 Water Technology Hydrodynamic Model 14 4 Entrainment of drifting marine biota 15 4.1 Position in western channel of North Arm 15 4.2 The process of entrainment 17 5 Marine ecosystem effects of entrainment 19 5.1 Holoplankton 19 5.1.1 Implications 20 5.2 Mangrove propagules 20 5.3 Seagrass propagules 20 5.4 Fish and squid eggs and larvae 21 5.5 Benthic invertebrates 21 5.6 Comparison with Victorian Desalination Project 22 6 Conclusion to Biological Entrainment 24 7 References 26 Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment

Tables Table 1. Current speed statistics (Royal Haskoning 2015) 13 Table 2. Comparison of Gas Import Jetty and Victorian Desalination seawater demand 22

Figures Figure 1. Natural marine ecosystem components at Crib Point 4 Figure 2. Conceptual model of Western Port marine ecosystem in Crib Point area 5 Figure 3. Critical water depths at Crib Point facility 7 Figure 4. Seawater intake environmental parameters at Crib Point facility 7 Figure 5. Environmental parameters at seawater intake: oblique and section 8 Figure 6. Variation in width and depth of seawater intake zone over tide cycle 8 Figure 7. Seawater intake grille at Victorian Desalination Plant 9 Figure 8. Islands and Bathymetry of Western Port 11 Figure 9. Water Movement in Western Port 12 Figure 10. Water Movement in Western Port relative to Crib Point 12 Figure 11. Water Movement at Crib Point from Water Technology Model 14 Figure 12. Probability of Entrainment from Water Technology Model 16 Figure 13. Time Series of Entrainment - from Water Technology Model 17 Figure 14. Entrainment with Distance - from Dispersion Analysis 18 Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment

Report to Report prepared by Ian Wallis and Scott Chidgey CEE Pty Ltd Unit 4, 150 Chesterville Rd Cheltenham, VIC, 3192 Ph. 03 9553 4787 Email. [email protected]

CEE (2018)

Cover photo: Crib Point Jetty (AGL)

Document History

Document Details Job Name AGL Gas Import Jetty Project Job No. IS210700 Modelling and Assessment of Biological Entrainment into Seawater Heat Document Exchange System File Ref Revision History Revision Date Prepared Checked By Approved by By Final (Ver 01) 27/07/18 Name S Chidgey S Ada S Ada Final (Ver 02) 29/08/18 Name S Chidgey S Ada S Ada AGL Gas Import Jetty Project Modelling and Assessment of Biological Entrainment into Seawater Heat Exchange System

EXECUTIVE SUMMARY AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

Regasification involves the heating of the LNG stored at -162oC using the ambient heat of seawater in Western Port. A daily volume up to 450,000 m3 (450 ML/d) (when operating at full capacity) of seawater from Western Port will be pumped at a rate of 5.2 m3/s through heat exchangers in the FSRU, and is used here as the upper limit for modelling.

AGL engaged Jacobs Group (Australia) Pty Ltd (Jacobs) and their specialist subconsultants to investigate the potential impacts of the seawater intake/discharge arrangements on environmental conditions in Western Port. The scope of this desktop assessment was to investigate the potential for biological entrainment into the seawater heat exchange for the FSRU and review potential implications to the marine ecosystem. This report was prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), · A referral under the Victorian Environment Effects Act 1978, · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act).

Initial modelling undertaken as part of this assessment shows that: · The seawater intake on the FSRU is positioned and designed to minimise the entrainment of fish. · Larvae that can maintain position in preferred nearshore habitats such as mangroves seagrasses and shallow nearshore waters should not be entrained. · Larvae, eggs and other propagules (e.g. mangrove seeds) that drift or travel on the water surface or near the seabed should not be entrained. · Short-lived larvae will only be entrained in proportions potentially >1 % in total if they commence their larval existence only within 3 km of Crib Point, and on the western side of North Arm. · Long-lived larvae will be entrained in proportions potentially >1 % in total if they commence their larval existence within about 10 km of Crib Point, and on the western side of North Arm. · The entrainment rate is expected to be about 2 to 3 % for sites on the western edge of the channel (including the adjacent mudflats) within about 8 km of Crib Point, and about 10 % for sites on the western edge of the channel (including the adjacent mudflats) within about 750 m of Crib Point (as shown in Figure 12). Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 2

· In the context of the wider Western Port area, for larvae commencing at 2 km or more north or south of the FSRU intake, less than 2 % of larvae would be entrained. · Overall, the proportion of larvae entrained from populations of widespread biota in Western Port is less than 1% and the effect is likely to be undetectable.

The modelling completed for this report and other supporting studies was based on the original FSRU seawater flow rate through the heat exchanger of 450,000 m3/day. AGL has advised that a seawater flow-through rate of 300,000 m3/day corresponding to a lower regasification rate is more likely. In this case, the proportion of plankton entrained may be reduced by approximately one third.

The assessment suggests that the design of the FSRU water intake will minimise the direct risk of biological entrainment and operation on many ecosystem components.

Estimation of the proportion of planktonic populations that may be entrained are dependent on a range of factors including: 1. The nature, distribution and annual variation of planktonic populations in North Arm of Western Port, which are currently undocumented; and 2. Hydrodynamic model configurations specific to entrainment.

It is recommended that the following studies are undertaken to provide greater certainty to the entrainment estimates reported in this study: · Particle entrainment modelling of North Arm be developed to provide entrainment proportion contours for FSRU heat exchange flow options. · A plankton and larval sampling program be designed and implemented to provide baseline information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. · A review of available information and literature on the effects of entrainment on semi- enclosed marine ecosystems to provide guidance on long-term ecosystem implications of plankton entrainment. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 3

1 INTRODUCTION 1.1 Project overview AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

The FSRU will be continuously moored to receive LNG cargos from visiting LNG carriers, store the LNG and re-gasify it as required to meet demand for high pressure pipeline gas.

Regasification involves the heating of the LNG stored at -162oC using the ambient heat of seawater in Western Port. A daily volume up to 450,000 m3 (450 ML/d) (when operating at full capacity) of seawater from Western Port may be pumped at a rate of 5.2 m3/s through heat exchangers in the FSRU, and is used here as the upper limit for modelling. This is a similar (but smaller) volume of seawater withdrawn by the Victorian Desalination Plant at Wonthaggi, which operates intermittently according to storage dam levels. The FSRU is also expected to operate with variations in flow depending on LNG supply and gas demand. AGL advises that the seawater flow the heat exchanger is likely to be 300,000 m3/d based on more recent estimates of regasification rate requirements.

1.2 Purpose of this report The scope of this desktop assessment was to investigate the potential for biological entrainment in to the seawater heat exchange for the FSRU and review potential implications to the marine ecosystem. This report was prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act); · A referral under the Victorian Environment Effects Act 1978; · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act). Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 4

2 INTAKE CONSIDERATIONS The FSRU will be located at the southern end of Crib Point Jetty, in the shipping basin approximately 500 m offshore from the inshore seagrass beds (Figure 1). Hence, heat exchange seawater will be withdrawn from the main channel of North Arm.

Figure 1. Natural marine ecosystem components at Crib Point (Position of FSRU shown in red)

The distribution of habitats (Figure 1) and conceptual model of the marine ecosystem in the vicinity of Crib Point (Figure 2) are based on CEE’s understanding of the distribution and characteristics of North Arm from previous reviews (Bok 2017, CEE 2009 and 2014, EPA 1996, 2001, Kimmerer and McKinnon 1987a and 1987b, Melbourne Water 2011, Ministry for Conservation 1975). The figures show that the FSRU is relatively remote from intertidal and nearshore marine ecosystem components and is located in an area of the channel characterised by plankton (plankton, larvae, eggs, small fish) and larger marine species including fish, diving seabirds such as penguins, cormorants and gannets and mammals such as seals and native water rats. Hence, a range of small marine species and, if appropriate mitigations are not put in place, some large biota (Figure 2) in the immediate vicinity have the potential to be drawn into the heat exchange system by the intake current to the seawater pumps and heat exchange pipework of the regasification facility on the FSRU. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 5

Figure 2. Conceptual model of Western Port marine ecosystem in Crib Point area (Adapted from CEE 2009)

This preliminary assessment examines the potential effects of entrainment on: · Large biota that may be caught and damaged or drowned on screens at the intake without appropriate mitigation; and · Small biota that may pass through screens and suffer further damage in the pumps and pipework of the heat exchangers as well as being exposed to chemical processes to prevent marine growth on the internal components of the water circulation circuit.

For this preliminary assessment, it is assumed that all biota passing through the heat exchanger will not survive the passage. However, in reality a proportion of biota will survive that are sufficiently robust to withstand the stresses during the short passage through the heat exchange system. Hence, the outcomes of this assessment are conservative (worst case) with respect to the effects of entrainment on marine biota.

2.1 Intake design to minimise effects on marine biota The configuration and position of the FSRU seawater intake involves the following environmental considerations: 1. Minimise intake and capture of large actively swimming marine organisms such as diving birds (cormorants and penguins), mammals (seals and native water rats), fish and molluscs (squid). · From this consideration, the intake should not be near the surface or near the seabed, and should be protected by appropriate screens. In addition, the intake should be designed so that water enters horizontally at a velocity of 0.1 to 0.15 m/s. · Many mobile vertebrate marine organisms (fish, birds, mammals) cannot detect vertical velocity components (upward or downward currents), so the water must enter the intake horizontally to enable marine vertebrates the opportunity to detect Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 6

the lateral currents and swim away from the intake. This is standard practice from modern heat exchange and desalination intake design. 2. Minimise entrainment of marine plankton, eggs and larvae. These are the very small plants and animals and the propagules of larger plants and animals that are found throughout the water column. They may have some capability for movement but are relatively passive swimmers and are carried with the prevailing currents. The waters of North Arm are relatively well mixed by strong tidal currents, but there may be the tendency for some species to be found in the upper or lower parts of the water column at different times of day or at different stages of their life-cycle, particularly during periods of low tidal currents. · From this consideration, the intake should not be near the surface or near the seabed. This assessment will be informed by the proportion of marine plankton, eggs and larvae that will not survive the entrainment process. The assessment includes modelling that takes into account the specified seawater inflow rate, location at Crib Point, residence time of waters in Western Port and ecological parameters.

2.1.1 FSRU seaworthiness and engineering considerations The design criteria described below are based on experience including the assessments and specified requirements for seawater intakes at Desalination Plants throughout Australia, and overseas power plants (e.g. US EPA cooling water intake regulations).

Practical, seaworthiness and engineering considerations for the design of the intake for an FSRU are not discussed in this document including: · Avoiding re-circulation of the heat exchange water discharge back into the intake · Seaworthiness of vessel with environmental intake · Biofouling (including drift material) management of the intake.

2.2 Position of intake in water column The sea surface and seabed are physical boundaries where movements of planktonic, pelagic biota (fish and molluscs) and air breathing animals (seals, water rats, penguins) are most likely to be concentrated. Hence, it is recommended to avoid placing the intake close to these two natural water column boundaries. These are also the boundaries where most drifting buoyant or dense material tend to accumulate.

AGL has advised that the seawater intake for the heat exchange system will be installed in the sea chest within the hull or as an attachment on the side of the vessel. The intake will therefore move up and down with the tide. In either case, the intake structure will be placed in a specific water depth range to reduce the potential for intake of biota or debris.

The water depth at the site is approximately 14 m from seabed to sea surface at lowest astronomical tide, with an additional 3 m depth at highest tides. To reduce the effect of the intake of seawater on ecosystem components, the seawater intake should be positioned a) At least 5 m above the seabed; and b) At least 4 m below the water surface.

Hence FSRU intakes are designed to be located in the water column layer between 5 m to 10 m above the seabed as shown in Figure 3. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 7

Sea surface - high tide 17 16 15 Sea surface - low tide 14 13 12 11 4 m 10 9 10 m 8 7 Locate intake between 5 m and 10 m from seabed 6 5 4 5m 3 2 1 Seabed - fine sand and silt 0

Figure 3. Critical water depths at Crib Point facility

2.3 Intake velocity – orientation and size of the intake The intake opening should be designed so that water is drawn into the intake in a horizontal plane at a speed < 0.15 m/s (Figure 4 and Figure 5). The intake should be oriented parallel to the ambient tidal currents, either flush with the hull of the FRSU or mounted on the hull or jetty piles.

Sea surface - high tide 17 16 15 Sea surface - low tide 14 13 14 m 12 11 4 m 10 9 10 m Intake velocity at grille: 8 Horizontal, 0.1 to 0.15 m/s, Seawater Intake 7 6 Perpendicular to ambient 5 4 5 m 3 2 1 Seabed - fine sand and silt 0

Figure 4. Seawater intake environmental parameters at Crib Point facility Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 8

Intake water Seawater Horizontal velocity Intake <0.15 m/s Screen

Figure 5. Environmental parameters at seawater intake: oblique and section

The volume of water drawn into the intake will be relatively constant, but the width (horizontal distance perpendicular to the screen) and depth (vertical distance above and below the screen) of the zone from which seawater will be entrained around the intake will vary as water currents change over the tide cycle.

Figure 6 shows the variation in the size of the zone from which seawater will be entrained over the tide cycle. The zone extends over a depth range of 2.6 m (at peak tidal currents) to 7 m (at slack water). Thus, for example, if the intake is at 8 m depth, seawater will be drawn into the heat exchanger at slack water from depths of 4.5 to 11.5 m below sea level. At peak currents, the depth range will be from 6.7 m to 9.3 m below sea level. The width of the zone will vary over the tide cycle from about 6 m to 15 m, depending on the current speed.

16 14 12 10 8 6 4 2

Depth range, m and Width, m 0 1 2 3 4 5 6 7 Hours in tidal cycle Width of intake zone Depth range of intake zone

Figure 6. Variation in width and depth of seawater intake zone over tide cycle Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 9

2.4 Intake grille and screens Intake grilles will reduce the likelihood of larger mobile marine animals and drifting debris from entering the seawater heat exchange system.

Environmental specifications for the Victorian Desalination Plant Intake were “Bar grille spacing 100 mm horizontal by 100 mm vertical or 50 mm horizontal spacing of vertical bars”. The installed screens are shown in Figure 7.

Figure 7. Seawater intake grille at Victorian Desalination Plant (Photo by M Venturoni)

2.5 Residual effect of intake on entrained biota As a result of the design features described above, the main unavoidable adverse effect of the heat exchanger system is to entrain the smaller marine organisms (very small fish, zooplankton and phytoplankton), drifting eggs and larvae in the central part of the water column in the intake zone. It is assumed for this preliminary assessment that all of entrained biota will not survive as a result of mechanical damage and exposure to chlorine biocide during passage through the heat exchange system. However, in reality it is likely that some biota will survive the entrainment process and relatively short period of exposure to chlorine as they pass through the heat exchange system.

The entrained biota comprise a wide range of planktonic plants and animals, larvae and eggs, from a wide range of plant and animal groups. The characteristics of the planktonic community in North Arm of Western Port has not been comprehensively studied since the early 1970s (Zooplankton - Macreadie 1972; phytoplankton and zooplankton - Ministry for Conservation 1975) and 1980s (zooplankton -Kimmerer and McKinnon 1985, 1987a, 1987b), but, like most marine bays, it comprises holoplankton populations (those that live their entire lives suspended in the water column such as phytoplankton and zooplankton) and meroplankton populations. Meroplankton include the eggs, larvae and other undeveloped life stage (propagules) of a wide range of adult marine plants, invertebrates and fishes. The adults may live in the water column (such as fish or squid) or on the seabed (including seaweeds, shellfish, crabs, sea urchins, sea squirts, fish). Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 10

Phytoplankton and zooplankton (holoplankton) generally reproduce in the water column, with different rates of reproduction or turnover between species, seasons and years. The characteristics and duration of the meroplanktonic life stages are highly variable between species. The larval life of species, their settlement and subsequent recruitment to the adult population is a highly complex process which can determine the population abundance and size classes of adults of the species. Seasonal and inter-annual variation in environmental conditions (currents, water temperature, primary productivity) can affect larval recruitment and is a key factor affecting the abundance and composition of many important ecological community components as well as commercial fisheries species.

Planktonic larvae originate from a range of adult biota. The adults may disperse eggs or larvae widely, resulting in widely dispersed planktonic larvae. Alternatively, they may lay eggs or release larvae in particular habitats that subsequently disperse along relatively defined hydrodynamic pathways.

At this stage of the Project, the effects of entrainment will be assessed in terms of the proportion of seawater that passes through the FSRU over representative time periods. This will enable subsequent assessment of the scale of effects on the marine ecosystem in relation to the area of North Arm affected and the biota most affected (see “Marine Ecosystem Protected Matters” CEE 2018b).

The assessment of entrainment effects of the seawater heat exchange system relies substantially on understanding of local hydrodynamics and flushing in Western Port, as discussed following sections. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 11

3 HYDRODYNAMICS OF WESTERN PORT Western Port is a large tidal inlet that extends for approximately 30 km from north to south and for approximately 40 km east to west. Western Port has an area of approximately 680 km2 and estimated volume of 0.8 km3. The features that strongly influence the hydrodynamics of Western Port are: 1. The two large islands in the Bay – French Island and Phillip Island 2. The extensive areas of shallow mudflats, particularly in the northern sector of the Bay 3. The relatively large tidal range (approximately 3 m) in Bass Strait at the entrances to Western Port. Figure 8 shows the two main islands and the bathymetry of Western Port.

Figure 8. Islands and Bathymetry of Western Port (Yellow areas less than 6 m deep; Red areas less than 3 m deep)

Average tides (MHHW to MLLW) range from 2.1 m in Bass Strait at Flinders in the entrance to Westernport to 2.2 m at Stony Point, Crib Point and Bouchier Channel in the north of the Bay (VRCA 2018). Largest tides may range up to 3.3 m at Stony Point. As a consequence of these large tidal ranges and the large surface area of the Bay, large volumes of water enter and leave Western Port each tidal cycle.

Estimates have been made of the tidal prism - the volume of seawater that enters and leaves Western Port each (average) tide cycle - from current measurements and hydrodynamic model predictions. Figure 9 shows the location of cross-sections at which the tidal prism has been calculated. About 960 million m3 (Mm3) of seawater enters Westernport on an average tide. Most of the water (about 900 Mm3) enters via the Western Entrance and only about 60 Mm3 through the eastern channel at San Remo. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 12

1 = Hinwood and Jones (1979); 2 = Hinwood (1979) Figure 9. Water Movement in Western Port

Approximately 350 Mm3 of the flows travels up the western side of North Arm and of this volume, about 200 Mm3 spreads over the mudflats in the north of the Bay. A further 130 Mm3 of seawater enters North Arm along the Arm’s eastern side (Hinwood Hydrodynamic Model, Figure 10).

Figure 10. Water Movement in Western Port relative to Crib Point Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 13

3.1 Net Water Movement The net water movement in Western Port is usually (but not always) clockwise around French Island and Phillip Island as illustrated by the wider arrows in the bottom chart of Figure 10. Persistent strong winds can reverse the direction of the net flow from clockwise to anticlockwise (Hinwood, 1979).

At Crib Point, most measurements and analyses (Hinwood 1979, EPA 2011) indicate an excursion of a theoretical water particle on the flood tide inflow of about 6 km up the channel (to the north), followed by an excursion of about 5.5 km down the channel (to the south). This results in a net tidal movement of about 0.5 km per tide cycle to the north. Thus, a theoretical water particle would move in a sinusoidal fashion up and down the western channel with a net movement of 0.5 km north per tide cycle (corresponding to 1.0 km/d, as there are two tide cycles per day). It is apparent that this theoretical particle would have travelled back and forth past Crib Point about 12 times (over six days) before finally escaping to the northern mudflats.

In practice, the picture is much more complex, as there are faster currents in the main channel and slower currents on the mudflats, so the tides on the mudflats turn about 30 minutes before the flow in the main channel, causing a net lateral movement. Draining of the mudflats at low tide and the effects of wind add further complexity. Nonetheless, for this preliminary assessment of entrainment by the FSRU at Crib Point, a simple oscillating current pattern is adopted, with a residence time at Crib Point of six days.

This is consistent with recent estimates of flood tide:ebb tide current ratios of 53:47 at Crib Point, which confirmed the clockwise circulation in Western Port (Royal Haskoning 2015), although ebb tides at the Crib Point extraction point of the model were stronger than flood tides, and southerly net water movement was noted at Stony Point and Long Island Point extraction points. These ‘anomalies’ were explained as resulting from eddies at the turn of the tide and from non-tidal effects in model inputs, as noted by Hinwood 1979. The use of tidal stream data alone shows net northerly water movement at all model extraction points, which results in net northerly flow along the western side of North Arm.

Table 1. Current speed statistics (Royal Haskoning 2015) Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 14

3.2 Water Technology Hydrodynamic Model The results from Water Technology hydrodynamic modelling for the Project (Water Technology 2017) show a completely different pattern of net water movement from earlier models, as illustrated in Figure 11.

Figure 11. Water Movement at Crib Point from Water Technology Model

The flood tide excursion averages 4.6 km to the north while the ebb tide excursion averages 6.0 km to the south. Thus, there is a net particle movement south of 1.4 km per tide cycle and a residence time of only two days. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 15

4 ENTRAINMENT OF DRIFTING MARINE BIOTA None of the small organisms taken into the heat exchanger are assumed to survive passage from the intake to the point of discharge. A first assessment of the potential effects of larvae abundance can be made by considering the intake volume as a proportion of the volume of water that flows past Crib Point each tidal cycle. This volume is known as the “tidal prism” as it is effectively the volume of water between high and low tide levels.

Hinwood and Jones (1979) calculated the tidal prism in the western channel of North Arm at Sandy Point from modelled tide and current patterns to be 350 Mm3 (see above) and this corresponds at Crib Point to approximately 300 Mm3.

In a tide cycle of 12.25 hours, the volume of seawater extracted by the FSRU is approximately 230,000 m3. Using these data, the bulk entrainment proportion of planktonic biota including larvae in the North Arm may be calculated as follows: Proportion entrained = Extraction x Residence time / Tidal prism = 230,000 x 12 / 300,000,000 = 0.009 (0.9 percent)

Thus, as a first approximation, the cooled seawater produced by the FSRU heat exchange system could potentially impact about 0.9 percent in total of planktonic biota in the western channel of North Arm in Western Port. This applies over a flushing period of six days, as estimated from net current flux in North Arm (Hinwood and Jones 1979) and assuming an even distribution of planktonic biota through the water column.

4.1 Position in western channel of North Arm The next step in the analysis of larvae entrainment was to examine the influence of position in the western channel, relative to Crib Point, on the probability of entrainment. Obviously larvae in the western side of the channel moving into Western Port, where the FSRU would be located, would have a high risk of entrainment than larvae on the eastern side.

Also, with a northward net current, larvae commencing their cycle at more than 6 km north of Crib Point would be largely unaffected, while larvae commencing close to Crib Point, particularly just to the south of Crib Point, would be at greater risk.

For this preliminary analysis, Water Technology were engaged to model the probability of particles being entrained, while being released at various points in Westernport. Three sites for release of larvae were selected for this preliminary analysis: 1. Western Channel near entrance to North Arm 2. Mangroves to north of Hastings Bay 3. Seagrass bank to north-east of Crib Point.

These three sites are shown in Figure 12.

In interpreting the Water Technology model results, it must be kept in mind that their model predicts a strong southerly drift past Crib Point, as illustrated in Figure 12, whereas other models predict a persistent northerly drift.

The Water Technology model operated by releasing particles each time step and then counting how many particles were ‘entrained’ in an intake flow of 450,000 m3/d at Crib Point. The results are summarised in Figure 12. It can be seen that about 3 percent of larvae from the mangrove site were captured, 1 percent of larvae from the seagrass site were captured (similar to the bulk flow analysis given earlier) and 0.2 percent of the particles released from the western channel site were captured. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 16

Figure 12. Probability of Entrainment from Water Technology Model

It can readily be appreciated that these results would be reversed if there were a net northward drift. It can also be appreciated that higher capture would occur with a six-day residence time compared to the two-day residence time of the Water Technology model.

Figure 13 shows a time series of larvae capture over two days (based on Water Technology’s two-day flushing period) illustrating the importance of the combination of the tide and the net drift (southerly in this scenario). On the ebb tide, up to 4 % of larvae from the mangrove area were entrained, and up to 1.5 % of larvae from the seagrass site.

In contrast, larvae from the western channel inlet were entrained in small proportions on the flood tide – although this result very much reflects the strong net southerly flow in the model. With a different model having a net northerly flow, it is expected that 3 to 4 % of the larvae entering North Arm could be entrained (effectively the inverse of the pattern in Figure 13. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 17

Figure 13. Time Series of Entrainment - from Water Technology Model

4.2 The process of entrainment As described in Section 2.3, to be entrained into the seawater intake, a larva has to enter the intake zone (shown in Figure 6) which extends over a depth range of 2.6 m (at peak tidal currents) to 7 m (at slack water). The width of the zone will vary from 6 to 15 m wide, or outwards from the intake screen (depending on the tidal current speed). With these dimensions of the intake zone and allowing for horizontal and vertical dispersion it has been calculated that in a single pass, the likelihood of larvae entering the intake (out to a distance of 15 m from the screen) is a maximum of 25 %, while the likelihood of passing the intake is a minimum of 75 %.

However, with a residence time of two days, and allowing for lateral mixing, the probability of entrainment increases to 68 %, as larvae flow back and forth four times past the intake screens (four passes with a 25 % risk of entrainment each time). However, over two days, the risk of entrainment decreases substantially with distance up and down North Arm from the intake, as illustrated in Figure 14. This figure was derived by applying typical rates of horizontal and vertical dispersion to a patch of water travelling to Crib Point from the north (on the ebb tide), and another patch from the south (on the flood tide). Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 18

100 90 80 70 60 50 40 10 % at 0.75 km 30 2 % at 1.9 km 20 1 % at 3 km 10

Probability of Entrainment, % 0 0 1 2 3 4 5 6 Distance from Intake, km

Figure 14. Entrainment with Distance - from Dispersion Analysis

The diagram on the left side of Figure 14 illustrates the effects of lateral dispersion. The greater the distance from Crib Point, the wider the zone from which particles of water can be entrained but, also, the smaller the probability of being entrained from any given flow path.

The diagram on the right side of Figure 14 illustrates the outcome in terms of the probability of entrainment of short-lived larvae. The entrainment of larvae from within 750m of the intake could possibly be 10 percent capture, but less than 2 percent of larvae commencing at 2 km or more north or south of the intake could be entrained. The effects on short-lived larvae are likely to be negligible from sites that are 3 km or more from Crib Point. The zone of high entrainment is illustrated by the ellipse around Crib Point in Figure 12. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 19

5 MARINE ECOSYSTEM EFFECTS OF ENTRAINMENT The effects of entrainment on marine ecosystem components in Western Port can be assessed at a high level using an understanding of known ecological processes and the hydrodynamic modelling discussed above.

The discussion above indicates that the risk of entrainment is greatest to planktonic biota that are evenly distributed over the water column within approximately 1 km of the FSRU.

5.1 Holoplankton The holoplankton are the very small plants (phytoplankton) and animals (zooplankton) that spend their entire life cycle in the water column and drift with the tidal currents. These biota are important components in the Western Port marine food chain.

The composition and productivity of holoplankton communities typically varies substantially over the seasons and between years due to a range of interacting physical (temperature, daylight), chemical (salinity, nutrients) and ecological (competition, predation) factors. Reproductive cycles may be very rapid at some times of year – typically in spring when water temperatures are increasing.

The characteristics of the holoplankton community in Westernport are likely to vary spatially due to regional differences in water quality, circulation and flushing. The characteristics of the holoplankton community in North Arm is likely to vary spatially from north to south and laterally due to the natural gradient in flushing time between the north and south of the Arm (Kimmerer and McKinnon 1987a), effects in of mixing and periodic inundation and drainage of the mudflats along the sides of the channels.

Conceptually, if a steady state of holoplankton characteristics were to be established (for example a typical, constant composition over a particular season), this would mean that plankton community turnover (or population replacement) would equal flushing time in that part of North Arm. The analysis of existing hydrodynamic models in Section 4.0 above indicated that flushing time (or residence time) in North Arm at Crib Point is between two and six days. Hence the natural replacement rate of constant state holoplankton population is between two days and six days. For a six-day residence time, simple continuity of mass modelling shows that the FSRU operating at 450,00 m3/day through flow would entrain 0.9 percent of the volume of North Arm, and the water passing through it, in that six-day period. The maximum proportion of holoplankton communities entrained over a flushing period could therefore be estimated at approximately 0.9 percent of the community of North Arm if it was distributed evenly over the water column and width and length of the North Arm. For a flushing period of two days, population replacement would have to be more rapid and only 0.3 percent of the North Arm holoplankton community would be entrained.

The proportion of the population entrained would be less if parts of the planktonic community were, for some reason, more concentrated along the sides of the channels or in the top or bottom of the water column, which are positions the intake is less likely affect. However, Water Technology’s entrainment model based on the finer scale hydrodynamic model of North Arm, shows that 10 percent of populations within 750 m of the FSRU may be entrained over a two-day flushing period, which would be equivalent to 30 percent for a six-day flushing period. Hence, estimates at this stage are strongly dependent on hydrodynamic model configuration.

The modelling completed for this report and other supporting studies was based on the original FSRU seawater flow rate through the heat exchanger of 450,000 m3/day. AGL has advised that a seawater flow-through rate of 300,000 m3/day corresponding to a lower regasification rate is more likely. In this case, the proportion of plankton entrained may be Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 20 reduced by approximately one third. It is apparent that estimates of entrainment are strongly dependent on FSRU operating volumes, hydrodynamic model configuration and planktonic distribution.

5.1.1 Implications The analysis so far indicates the proportion of holoplankton entrained over the entire North Arm area is likely to be small (<1 percent) in terms of the total standing population of North Arm. However, the modelling shows that 10 percent (and up to 30 percent depending on model configuration) of the population within 750 m of the FSRU may be entrained at full operating capacity. This would seem likely to result in changes to the population structure of the plankton community in the immediate locality of the FSRU. The long term consequences of this change on other components of the marine ecosystem in the vicinity of the FSRU that are strongly dependent on plankton are uncertain.

The proportion of populations entrained are likely to decrease at least in proportion to reduction in water flow through the FSRU. Hence if flows through the FSRU are initially one third of full capacity and the FSRU operates intermittently over the first years, then entrainment during operation would be proportionately less.

Robust entrainment modelling and further understanding of plankton distribution and temporal variability in Western Port plankton populations is required to provide evidence- based context for further assessment of potential long-term and cumulative effects of entrainment on plankton communities and flow-on to interconnected ecosystem components. The modelling should be based on heat exchange flows corresponding to realistic operational scenarios. For example, a reduction in heat exchange flows from the modelled 450,000 m3/day to 300,000 m3/day is likely to reduce the proportion of entrainment by approximately one third.

Comprehensive review of literature on the effects of entrainment on semi-enclosed marine ecosystems is recommended to inform further assessment of potential effects of full production of the FSRU.

It is recommended that: · Entrainment and hydrodynamic modelling for North Arm be developed to provide entrainment proportion contours based on heat exchange flows corresponding to realistic operational scenarios. · An intensive plankton sampling program be developed to provide information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. · Available information of literature on the effects of entrainment on semi-enclosed marine ecosystems be reviewed.

5.2 Mangrove propagules Mangroves in Western Port reproduce by releasing floating propagules that disperse with surface water currents influenced by wind. Mangroves are located discontinuously around the perimeter of Western Port. The closest mangroves are located more than 1 km from the proposed intake position. Floating propagules from these mangroves should not be entrained by the seawater heat exchange system.

5.3 Seagrass propagules Seagrasses in North Arm of Western Port reproduce by releasing propagules and seeds and by vegetative fragments. Propagules and vegetative fragments tend to float and disperse Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 21 widely. These floating propagules are unlikely to be entrained by the seawater heat exchange system. Seeds tend to accumulate within existing seagrass beds and should not be entrained by the seawater heat exchange system.

5.4 Fish and squid eggs and larvae Most adult and mobile juvenile fish should not be directly affected by entrainment due to the design features of the intake and their ability to avoid the intake current.

Fish that breed outside North Arm but migrate into Western Port should not be directly affected by entrainment. The proportion of planktonic eggs and larvae of such species entrained that are produced outside North Arm is likely to be negligible as indicated by 0.2 % entrainment at near the entrance to North Arm from the Western Entrance (Figure 12).

Many larvae from fish that are resident in sheltered waters such as Western Port avoid predators associated with open waters or bare seabed by maintaining their position within favoured habitats, such as seagrasses and shallow waters. Juvenile fish, small species and larvae that are associated with shoreline or nearshore habitats such as seagrasses, mangroves, mudflats or channel slopes may have a low likelihood of entrainment due to the position of the intake in the water column at Berth 2, which is 500 m offshore from the seagrass beds and 300 m from the upper slope of the channel.

Some species attach eggs to the seabed (such as elephant fish and some squid and octopus). Juveniles with sufficient mobility to migrate from Western Port or avoid entrainment hatch directly from the eggs. The risk of entrainment to populations of such species is negligible.

Fish with planktonic eggs and larvae (anchovies) tend to breed over large areas of water bodies, with widespread dispersal and exchange of eggs, larvae and juveniles. A proportion of planktonic eggs and larvae of such species that are produced within North Arm may be affected by entrainment depending on the location of their release and the duration of the stages that are predominantly planktonic.

Figure 12 indicates that 10 % removal is possible for some larvae produced within 750 m of the FSRU. It is possible that larvae and juvenile fish that may be migrating along a relatively narrow route along the western side of North Arm channel to or from northern Western Port may also be at greater risk than more dispersed migratory paths or drift patterns. Although we are not aware of any particular species that may migrate along a narrow path centred on Crib Point jetty.

The modelling and plankton sampling program recommended in Section 5.1.1 should include consideration of the fish egg and larval content of the plankton communities sampled.

5.5 Benthic invertebrates Much of Western Port’s seabed comprises soft seabed that is inhabited by a range of benthic invertebrates including sandworms, crustaceans, molluscs and echinoderms, with a wide range of reproductive strategies, including planktonic stages. There are few natural hard seabeds (reefs) in North Arm, with the notable exception of Crawfish Rock located more than 10 km north of Crib Point.

It is expected that planktonic propagules from soft seabed benthic invertebrates would be dispersed from widespread habitats over a large area. A proportion of these planktonic propagules will settle close to their release point, while others settle at distances from their release point dependent on the duration of the larval period and the strength of net transport currents. There is considerable mixing of planktonic propagules of different larval-age from Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 22 different areas within North Arm and elsewhere in Western Port. Larvae from a wide range of source locations may settle at any one location (including the FSRU) over a period of time.

Larval durations of invertebrates vary widely, if they are known at all. For example, some species of thalassinidian shrimps related to those in Western Port have larval periods (with four or five stages) totalling more than 15 days, others have larval periods (with only two or three planktonic stages) totalling less than 14 days, while others have been estimated at 6 weeks (Butler, Reid and Bird 2009). Figure 12 indicates that 10 % entrapment of larvae that are produced in close vicinity of the FSRU (within 750 m) is possible. However, this may indicate that a particular population of invertebrate that is only found close to the location of the FSRU, with a planktonic period less than 8 days may be at risk from entrainment.

5.6 Comparison with Victorian Desalination Project The proposed Crib Point Gas Import Jetty Project heat exchange system will withdraw seawater from Western Port at Crib Point at rate of 5.2 m3/s. The Victorian Desalination Plant (VDP) was planned to withdraw seawater from Bass Strait offshore from Wonthaggi at a rate of 18.5 m3/s (ASR 2008), although its present intake capacity is approximately 11.6 m3/s. A summary comparison of the two systems is shown in Table 2.

Table 2. Comparison of Gas Import Jetty and Victorian Desalination seawater demand Character Heat exchange intake Desalination intake Flow rate 5.2 m3/s 11.6 m3/s Operational requirement Initially likely to be intermittent Intermittent demand Operational period Initially likely to be intermittent <4 months per year Annual volume (estimate) 160 GL capacity 114 GL 2016, 34 GL 2017 (Likely less in initial period) (365 GL capacity) Location North Arm Western Port Bass Strait, Wonthaggi Water depth at intake 14 m plus 3.2 m tide 20 m plus 3 m tide Water depth of intake Between 5 m and 10 m above Between 4 m and 7.5 m seabed above seabed Intake water body Embayment 5 km wide Open coast Currents at intake Strong currents Week tidal currents Net current at intake Strongly tidal with variable net Seasonally dependent current

The table shows that there are substantial differences in the conditions at the intakes and the volumes and durations of seawater actually used in the two systems. Net current is the key factor determining the proportion of larvae entrained at a location. Entrainment models also differed between the two projects due to differences in: spatial scales and boundary conditions at locations (bay versus open ocean); tidal currents (strong versus weak); net water movement drivers (tidal currents and complex topography versus seasonal winds).

Entrainment proportions were estimated to be less than 1.5 % within 1 km of the intake for all durations modelled (1 to 14 days) for annual net current conditions at VDP (ASR 2008). Net current at VDP is dependent on regional winds. Hence, while entrainment proportions were less than 1% at 1 km of the intake for most combinations of larval duration and season and year, there were noticeable differences between seasons in the two years modelled due to differences in winds and net current.

It could be expected that the more confined nature of the water body of North Arm would result in higher proportions of larvae entrained at Crib Point despite the 50 percent lower intake flow rate relative to larger intake flow rate at open coastline at Wonthaggi. The Water Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 23

Technology and CEE modelling shown above shows that entrainment proportions up to 10% were possible for some larvae within 750 m of the intake based on currents predicted at Crib Point, but that entrainment was less than 1 percent over the whole of North Arm. The independent models of entrainment proportion are therefore generally consistent given the differences in intake flow and study boundary volumes.

Prediction of the proportion of larvae entrained is dependent on accurate estimation of tidal currents and net flux. As noted above, further studies are required to a. resolve differences between tidal currents and net flux estimates from existing hydrodynamic models in Western Port and b. characterise temporal and spatial scales of plankton community populations in Western Port. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 24

6 CONCLUSION TO BIOLOGICAL ENTRAINMENT Based on this analysis, the following conclusions are drawn: · The seawater intake on the FSRU is positioned and designed to minimise the entrainment of fish and large mobile biota. · The seawater intake on the FSRU is positioned and designed to minimise the entrainment of eggs, larvae, other planktonic biota and propagules that drift or travel in the water surface layer or near the seabed. · The location of the FSRU at the end of the Crib Point Jetty more than 500 m offshore from the low tide mark substantially reduces the likelihood of entrainment of larvae that can maintain position in preferred nearshore habitats such as mangroves, seagrasses and shallow nearshore waters. · Short-lived, dispersed larvae and eggs will only be entrained in proportions potentially >1 % in total if they commence their larval existence only within 3 km of Crib Point, and on the western side of North Arm. · Long-lived, highly dispersed larvae will be entrained in proportions potentially >1 % in total if they commence their larval existence within about 10 km of Crib Point, and on the western side of North Arm. · The entrainment rate at full operational capacity of the FSRU for immobile plankton that are dispersed over the column is expected to be about 2 to 3 % for sites on the western edge of the channel (including the adjacent mudflats) within about 8 km of Crib Point, and about 10 % for sites on the western edge of the channel (including the adjacent mudflats) within about 750 m of Crib Point but that entrainment was less than 1 percent over the whole of North Arm. · In the context of the wider Western Port area, for larvae commencing at 2 km or more north or south of the FSRU intake, less than 2 % of larvae would be entrained. · Overall, the proportion of larvae entrained from populations of widespread biota in Western Port is less than 1% and the effect is likely to be undetectable.

The modelling completed for this report and other supporting studies was based on the original FSRU seawater flow rate through the heat exchanger of 450,000 m3/day. AGL has advised that a seawater flow-through rate of 300,000 m3/day corresponding to a lower regasification rate is more likely. In this case, the proportion of plankton entrained may be reduced by approximately one third. It is apparent that estimates of entrainment are strongly dependent on FSRU operating volumes, hydrodynamic model configuration and planktonic distribution

Estimation of the proportion of planktonic populations that may be entrained are dependent on a range of factors including: 1. The nature, distribution and annual variation of planktonic populations in North Arm of Western Port, which are currently undocumented and 2. Hydrodynamic model configurations specific to entrainment. 3. Realistic regasification operational scenarios be defined so that the range of potential entrainment effects can be modelled.

It is recommended that the following studies are undertaken to provide greater certainty to the entrainment estimates reported in this study: · Particle (or equivalent) entrainment modelling for North Arm be developed to provide entrainment proportion contours · A plankton and larval sampling program be designed and implemented to provide information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 25

· Available information of literature on the effects of entrainment on semi-enclosed marine ecosystems be reviewed to provide guidance on long-term ecosystem implications of plankton entrainment. · Realistic regasification operational scenarios be defined so that the range of potential entrainment effects can be modelled. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 26

7 REFERENCES ASR 2008. Particle Dispersal Modelling: Seasonal and spatial variations. Victorian Desalination Project. ASR Ltd, Raglan New Zealand. EPA 1996. The Western Port Marine Environment. EPA Publication no 493. Environment Protection Authority. EPA 2001. Protecting the Waters of Western Port and Catchment. EPA Publication no 797. Environment Protection Authority. Butler S N, Reid M and F L Bird 2009. Population biology of the ghost shrimp Tryapaea australiensis and Biffarius arenosis (Decapoda Thalassinidae), in Western Port, Victoria. Memoirs of Museum Victoria 66:43 - 59 CEE 2009. Port of Hastings Stage 1 Development. Marine Ecosystem Preliminary Considerations. Report to AECOM and Port of Hastings Corporation. CEE, Melbourne, August 2009. CEE 2014. Port of Hastings Seagrass Monitoring Pilot Study. Report to Port of Hastings Development Authority. CEE Melbourne June 2014. CEE (2018a) Plume Modelling of Discharge from LNG Facility at Crib Point, Western Port – AGL Gas Import Jetty Project. Report for AGL. Report for AGL. CEE (2018b) Marine Ecosystem Protected Matters – AGL Gas Import Jetty Project. Report for AGL. CEE (2018c) Assessment of effects of cold-water discharge on marine ecosystem at Crib Point – AGL Gas Import Jetty Project. Report for AGL. Bok M, Chidgey S and P Crockett 2017. 5 years on: Monitoring of Long Island Point's Western Port wastewater discharge. Conference Paper, APPEA Annual Conference 2017. EPA 2011. Environment Report - Port Phillip and Western Port Receiving Water Quality Modelling: Hydrodynamics. (2011) EPA Publication 1377. Harris JE, Hinwood JB, Marsden MAH & Sternberg RW 1979. Water movement, sediment transport and deposition. Western Port, Victoria’, Marine Geology, Vol. 30, 131–61. Harris JE, Robinson JB 1979. Circulation in Western Port, Victoria, as deduced from salinity and reactive silica distributions. Marine Geology, Vol. 30 101–16. Hinwood J. B. and Jones J.C.E. 1979. Hydrodynamic Data for Western Port, Victoria. Marine Geology 30, 47-63. Hinwood JB 1979, Hydrodynamic and transport models of Western Port, Victoria. Marine Geology, Vol. 30, 117–30. Kimmerer W and A D McKinnon 1985. A comparative study of the Zooplankton in two adjacent embayments: Port Phillip and Westernport Bay, Australia. Estuar coast Shlf Sci 21: 145-159. Kimmerer W and A D McKinnon 1987a. Zooplankton in a marine bay.I. Horizontal distributions to estimate net population growth rates. Mar Ecol Prog Ser 41: 43- 52. Kimmerer W and A D McKinnon 1987b. Zooplankton in a marine bay.II. Vertical migration to maintain horizontal distributions. Mar Ecol Prog Ser 41: 53-60. Melbourne Water (2011). Understanding the Western Port Environment. A summary of knowledge and priorities for future research. Editors M J Keough and R Bathgate for Melbourne Water, Port Phillip and Westernport CMA, Victoria. Ministry for Conservation (1975) Westernport Bay Environmental Study 1973-1974. Ministry for Conservation, Victoria. Crib Point Gas Import Jetty Project – Modelling and assessment of biological entrainment 27

Royal Haskoning 2015. MetOcean Conditions at Existing Berths (HY-WP-27). Technical Note to Port of Hastings Development Authority, Draft 21 May 2015. VRCA 2018. Vic Tides 2018 Edition 2. Victorian Regional Channels Authority. Water Technology 2017. Hydrodynamic & Water Quality Modelling, Western Port Bay. Report to AGL Wholesale Gas Ltd.

Attachment 9

Report to: Jacobs Group (Australia) Pty Ltd

AGL Gas Import Jetty Project Crib Point, Western Port

Marine Ecosystem Protected Matters Assessment

FINAL

30 August 2018 AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment ii AGL Gas Import Jetty Project Crib Point, Western Port

Marine Ecosystem Protected Matters Assessment

Contents Executive Summary 1 1 Introduction 5 1.1 Project overview 5 1.2 Introduction to Western Port marine environment 5 1.3 Purpose of this report 8 1.4 Scope 8 2 Legislative Instruments 9 2.1 Commonwealth EPBC Act 1999 9 2.2 Environment Effects Act 1978 9 2.3 Victorian FFG Act 1988 10 3 Marine Environment Protected Matters 11 4 Western Port Ramsar site 13 4.1 Areas important for waterbirds 16 5 EPBC Act and FFG Act Marine Protected Species 18 5.1 Endangered species 19 5.1.1 Blue Whale 19 5.1.2 Southern Right Whales 20 5.1.3 Leatherback Turtle 21 5.1.4 Loggerhead Turtle 22 5.2 Vulnerable species 23 5.2.1 Humpback Whales 23 5.2.2 White Shark 25 5.2.3 Australian Grayling 25 5.2.4 Green Turtle 26 5.3 Migratory species 26 5.3.1 Brydes Whale 26 5.3.2 Pygmy Right Whale 26 5.3.3 Dusky Dolphin 26 5.3.4 Killer whale 27 5.3.5 Mackerel Shark 27 5.4 Additional FFG Act listings 27 5.4.1 Grey Nurse Shark 27 5.4.2 Southern Bluefin Tuna 27 5.4.3 Australian or Tasmanian Whitebait 27 5.4.4 Australian Mudfish 28 5.4.5 Pale or flatback mangrove goby 28 5.4.6 Marine Invertebrates 29 5.4.7 San Remo Marine Community 37 5.5 EPBC Act threatening processes 37 5.5.1 Introduced marine species 38 AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment iii

6 Preliminary Assessment of Project effects 41 6.1 Project processes and potential impact pathways 41 6.1.1 Entrainment effects and mitigation 42 6.1.2 Effects of cold seawater discharge 43 6.1.3 Chlorine residual in seawater discharge 44 6.2 Endangered species – preliminary assessment 45 6.3 Vulnerable species – preliminary assessment 45 6.3.1 Australian Grayling 46 6.4 Migratory species – preliminary assessment 48 6.5 Preliminary assessment of FFG marine listed species and communities 49 6.5.1 Pale mangrove goby or flatback mangrove goby 49 6.5.2 Ghost shrimps 49 6.6 Ramsar area 51 7 Conclusion 54 8 References 56

Tables Table 1. Marine protected species and need for further information 2 Table 2. Summary of marine Protected Environmental Matters within 10 km of Crib Point 11 Table 3. Protected species in region of Crib Point Jetty (at September 2017) 18 Table 4. Flora and Fauna Guarantee Act 1988 - listed marine invertebrates 29 Table 5. Chlorine ecosystem protection guidance values 44 Table 6. Assessment of Ramsar Selection Criteria 52

Figures Figure 1. Marine habitat distribution in Western Port 6 Figure 2. Natural marine ecosystem components at Crib Point 7 Figure 3. Conceptual model of Western Port marine ecosystem in Crib Point area 7 Figure 4. Protected Matters Search area 11 Figure 5. Western Port Ramsar site 13 Figure 6. Marine National Parks within and adjacent to Western Port Ramsar site 16 Figure 7. Key roosting, feeding and breeding habitat for waterbirds in Western Port 17 Figure 8. Distribution of Blue Whales 20 Figure 9. Distribution of Southern Right Whales 21 Figure 10. Sightings of Leatherback Turtles in Victoria (DSE, 2007) 22 Figure 11. Turtle sightings in Southeastern Australia 23 Figure 12. Distribution of Humpback Whales 24 Figure 13. Whale sightings compiled for Two Bays Project 2014 to 2017 24 Figure 14. Distribution of flatback mangrove goby (Mugilogobius platynotus) 28 Figure 15. Distribution of Western Port ghost shrimp Pseudocalliax tooradin 31 Figure 16. Distribution of ghost shrimp Michelia microphylla 32 Figure 17. Distribution of brittle star (Amphiura triscacantha) 33 Figure 18. Distribution of the sea cucumber (Apsolidium densum) 34 Figure 19. Distribution of the sea cucumber Apsolidium handrecki in Victoria 35 Figure 20. Distribution of the chiton (Bassethullia glypta) in Victoria 36 Figure 21. Seawater intake environmental parameters at Crib Point facility 42 Figure 22. Behaviour of cold-water discharge from FSRU at Crib Point 43 Figure 23. Maximum extent of cold water field cross-section (concept) 44 Figure 24. Location of grayling waterways in Upper North Arm 47 Figure 25. General water movement in Western Port 48 Figure 26. Locations of collection of FFG listed ghost shrimps near Crib Point 50 AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment iv

Report to Report prepared by Scott Chidgey, Peter Crockett CEE Pty Ltd Unit 4, 150 Chesterville Rd Cheltenham, VIC, 3192 Ph. 03 9553 4787 Email. [email protected]

CEE (2018): AGL Gas Import Jetty Project Crib Point, Western Port. Marine Ecosystem Protected Matters Assessment. Report to Jacobs by CEE Pty Ltd, Melbourne.

Cover photo: Crib Point Jetty (AGL)

Document History

Document Details Job Job Name AGL Gas Import Jetty Project IS210700 No. Document Marine Ecosystem Protected Matters Assessment File Ref Revision History Version Date Prepared Checked By Approved By by Final (Ver 01) 27 July Name S Chidgey S. Ada S. Ada 2018 Final (Ver 02) 30 Aug Name S Chidgey S. Ada S. Ada 2018 AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 1

Marine Ecosystem Protected Matters Assessment

EXECUTIVE SUMMARY AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

The facility would be located in a section of Western Port (North Arm), which is a diverse but compact marine environment. It comprises vast intertidal mudflats with saltmarsh, seagrass and mangrove habitats as well as steep subtidal sloping banks with seagrass and deep channels that connect the north of the bay with the oceanic waters of Bass Strait in the south.

These characteristics contribute to the listing of a large part of Western Port as a Ramsar wetland of international significance and the allocation of distinct areas as National Parks. Many of the animal and plant species are not specifically protected or listed for conservation value, but the combination of mangroves and seagrasses, saltmarsh, fish, birds, crustaceans, worms and other unique invertebrates all form the Western Port marine ecosystem that is valued by the public.

The scope of this assessment was to review relevant Commonwealth and Victorian legislation for marine protected areas, protected marine species (flora and fauna, excluding birds and terrestrial fauna) and listed processes that may be relevant to the Project. Various marine species, habitats and ecological communities are protected by the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the State Flora and Fauna Guarantee Act 1988 (FFG Act). In some cases, species or places are listed on both the EPBC and FFG Acts. The broader ecosystem values of Western Port outside of the area relevant to the Project are assessed in the context of Western Port’s Ramsar values. These matters are relevant to decisions in relation to the Project referrals under the Environment Effects Act 1978 (Vic) (EE Act) and the EPBC Act.

The Western Port Ramsar site was designated as a wetland of international significance in 1982. The Ramsar site covers 59,950 ha of Western Port including Crib Point. Western Port is one of eleven Victorian Ramsar sites in Victoria and is the third most important area for wading birds in Victoria. All Ramsar sites are a matter of national environmental significance (MNES) under the EPBC Act. Potential long-term change to the ecological character of a Ramsar wetland is also a trigger for referral of a project under the EE Act.

A review of marine Commonwealth EPBC Act MNES and the State FFG Act listed species has been completed for the Project. The assessment identified 33 threatened marine species and one marine community that the Acts list may occur in Western Port. This assessment excluded birds which are assessed in the Jacobs Flora and Fauna Assessment Report. The identified threatened marine species are listed in Table 1. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 2

Table 1. Marine protected species and need for further information Further Common name Scientific name EPBC FFG information required* Mammals Blue Whale Balaenoptera musculus Endangered, Migratory Listed Unlikely Southern Right Whale Eubalaena australis Endangered, Migratory Listed Unlikely Humpback Whale Megaptera novaeangliae Vulnerable, Migratory Listed Unlikely Brydes Whale Balaenoptera edeni Migratory Unlikely Pygmy Right Whale Caperea marginate Migratory Unlikely Killer Whale Orcinus orca Migratory Unlikely Dusky dolphin Lagenorhynchus obscurus Migratory Unlikely Burrunan Dolphin Tursiops australis Listed marine (NA) Listed Unlikely Sharks White shark Carcharodon carcharias Vulnerable, Migratory Listed Unlikely Grey nurse shark Carcharius Taurus Listed Unlikely Mackerel Shark Lamna nasus Migratory Unlikely Freshwater/Marine Migratory Fish Australian grayling Prototroctes maraena Vulnerable Listed YES Australian mudfish Neochanna cleaver Listed Unlikely Marine Fish Pale Mangrove Goby Mugilogobius paludism Listed YES Southern Bluefin Tuna Thunnus maccoyii Listed Unlikely Australian Whitebait Lovettia sealii Listed Unlikely Reptiles Leatherback Turtle Dermochelys coriacea Endangered, Migratory Listed Unlikely Loggerhead Turtle Caretta caretta Endangered, Migratory Unlikely Green Turtle Chelonia mydas Vulnerable, Migratory Unlikely Marine Invertebrates Southern hooded shrimp Athanopsis australis Listed Unlikely Ghost shrimp Pseudocalliax Tooradin Listed YES Ghost shrimp Michelea microphylla Listed YES Brittle star Amphiura triscacantha Listed Unlikely Sea-cucumber Apsolidium densum Listed Unlikely Sea-cucumber Apsolidium handrecki Listed Unlikely Brittle star Ophiocomina australis Listed Unlikely Sea-cucumber Pentocnus bursatus Listed Unlikely Sea-cucumber Thyone nigra Listed Unlikely Sea-cucumber Trochodota shepherdi Listed Unlikely Chiton Bassethullia glypta Listed Unlikely Opisthobranch Platydoris galbana Listed Unlikely Opisthobranch Rhodope genus Listed Unlikely Stalked Hydroid Ralpharia coccinea Listed Unlikely

CEE’s review found that many of the marine species listed under the State and Commonwealth Acts were relatively widely distributed, that Western Port represented a small component of their range and that Western Port was not recognised as a significant aggregation, breeding or feeding location or migratory path for most EPBC identified species and many FFG listed species (excluding water birds).

As shaded grey in the table above, the review identified four species that required further information to inform project risk screening and assessment: AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 3

· Australian Grayling Prototroctes maraena: EPBC Act ‘Vulnerable’; FFG listed · Pale Mangrove Goby Mugilogobius paludis: FFG listed · Western Port ghost shrimp Pseudocalliax tooradin: FFG listed · Small-gilled ghost shrimp Michelea microphylla: FFG listed

The potential impact pathways of the Project on these species were identified as: · Cold water effects of the discharge of cold seawater from the FSRU to the waters of Western Port in the vicinity of Crib Point · Toxicity effects of chlorine related chemicals in the discharge of the heat exchange water discharged from the FSRU to the waters of Western Port in the vicinity of Crib Point · Entrainment of larvae (all four species) or juveniles (Grayling) into the heat exchange system of the regasification process on the FSRU

These pathways have been described and modelled in separate reports on hydrodynamic and discharge mixing modelling (CEE, 2018a), heat exchange seawater entrainment modelling (CEE, 2018b), the effects of cold-water discharge assessment on the marine ecosystem (CEE 2018c) and chlorine behaviour investigation and toxicity modelling (CEE, 2018d). Measures to mitigate the effects of the processes on the marine ecosystem also have been described in these reports. In summary: · The extent of effect of these processes is likely to be restricted within the lower North Arm of Western Port. · The extent of effects of cold-water and chlorine toxicity in the discharged waters are likely to be restricted to an area approximately 200 m north and south and 60 m east and west of the discharge point and species that are located at water depth greater than 12.5 m. · Entrainment is unlikely to affect species: o that are capable of movement independent of tidal currents § with propagules that predominantly remain within intertidal or shallow water habitats, § disperse along the edges of the channels in Western Port and § disperse within 4 m of the surface or within 4 m of the seabed. · Entrainment may affect planktonic populations within North Arm to an area of approximately 1 km north and south of the FSRU, however entrainment was predicted to be less than 1 percent over the whole of North Arm.

An examination of information about the Australian Grayling indicated that adult populations in the rivers and streams would not be exposed to impact pathways and that the proportion of larvae of these species that might disperse via North Arm and be affected by Project processes was low.

Museum of Victoria personnel advised that the Pale Mangrove goby Mugilogobius paludis was synonymous with the more common flatback goby Mugilogobius platynotus, which is not listed on the FFG Act threatened species list.

There is evidence of the Western Port ghost shrimp Pseudocalliax tooradin and the small- gilled ghost shrimp Michelea microphylla being known near Crib Point more than 50 years ago. The Western Port ghost shrimp Pseudocalliax tooradin is known only from a total of five records, and the ghost shrimp small-gilled Michelea microphylla from only one specimen. Further examination of information on both ghost shrimps indicated that they had restricted distributions in Western Port that may indicate susceptibility to entrainment, cold-water and chlorine toxicity effects of the FSRU seawater heat exchange processes if still present in the area. Further investigations of the present distribution of these species are recommended. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 4

The general outcome of the reports indicates that the direct effects of the full-scale operation of the FSRU on the marine ecosystem in the Ramsar area relate to discharge of cold-water, discharge of residual chlorine and entrainment of larvae and plankton. As stated above, the extent of cold-water and chlorine toxicity effects are likely to be restricted to an area approximately 200 m north and south and 60 m east and west of the discharge point in water depth from approximately 12.5 m to 17 m. This represents an area of approximately 5 ha, which is less than 0.5 % of the seabed in North Arm1.

Entrainment of up to 10 percent of some plankton and larvae may extend to 750 m north and south from the FSRU, but overall entrainment in the whole of North Arm is expected to be less than 1%. The modelling completed for this report and other supporting studies was based on the original FSRU seawater flow-through rate of 450,000 m3/day (450 ML/day). AGL has advised that a seawater flow-through rate of 300,000 m3/day (300 ML/day), corresponding to a lower regasification rate is more likely. In this case, the proportion of plankton entrained may be reduced by approximately one third.

The longer term effects of entrainment on planktonic populations (including some planktonic larvae and eggs) are uncertain due to the possible natural long term variability in plankton community composition and the intermittent and variable operation of the FSRU, which depends on uncertain national and State energy supply options and State energy demands in the near future and over the next decades. Further investigations are recommended to document the distributions of marine ecosystem components in the vicinity of the discharge, including planktonic populations, which were previously systematically documented more than 40 years ago. Further modelling is also recommended to determine residence times and the proportions of entrainment for different operational scenarios of the FSRU at Crib Point to further inform estimation of longer term effects of entrainment.

AGL is committed to further marine environmental studies prior to operation and is presently considering: · Benthic invertebrate sampling to document the present characteristics and distribution of epibiota and infauna including targeted investigation to evaluate the existence of ghost shrimp species; · Measurement of short-term and long-term water temperature variations to provide natural variation context for assessment of cold-water discharge differentials · Refinement of North Arm hydrodynamic models to assist refinement of discharge dispersion models and entrainment estimation models · Development of entrainment models for North Arm to provide plankton entrainment proportion contours · A plankton and larval sampling program to provide information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. · Review of available literature on the effects of entrainment on semi-enclosed marine ecosystems to provide guidance on long-term ecosystem implications of plankton entrainment.

These studies will inform a works approval application under the Environment Protection Act 1970 and in accordance with the relevant associated regulations, including the State Environment Protection Policy (Waters of Victoria).

1 Percentage based on the area of North Arm which is greater than 10 m depth. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 5

1 INTRODUCTION 1.1 Project overview AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

Jacobs Group (Australia) Pty Ltd (Jacobs) was engaged by AGL to undertake planning and environmental assessments for the AGL Gas Import Jetty Project. Jacobs engaged CEE Environmental Scientists and Engineers to define the marine environmental characteristics and identify key potential risks to the marine environment from the development and operation of the Project.

There are several other activities that are related to the AGL Gas Import Jetty Project. These include the Jetty Upgrade and the Crib Point to Pakenham Gas Pipeline Project which are the subject of separate assessment and approval processes carried out by separate entities.

Jacobs engaged CEE to define the marine environmental characteristics with respect to protected matters legislation and identify key potential risks to the marine environment from the development and operation of the Project.

1.2 Introduction to Western Port marine environment Western Port is a diverse but compact marine environment. It comprises vast intertidal mudflats with saltmarsh, seagrass and mangrove habitats as well as steep subtidal sloping banks with seagrass and deep channels that connect the north of the bay with the oceanic waters of Bass Strait in the south (Figure 1). AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 6

Figure 1. Marine habitat distribution in Western Port (Red dots are EPA water quality monitoring sites)

The distribution of habitats (Figure 2) and conceptual model of the marine ecosystem in the vicinity of Crib Point (Figure 3) are based on CEE’s understanding of the distribution and characteristics of North Arm from previous reviews and studies (Bok et al 2017, CEE 2009 and 2014, EPA 1996 and 2001, Kimmerer and McKinnon 1987a and 1987b, Melbourne Water 2011, Ministry for Conservation 1975). The figures show that the FSRU is more than 500 m offshore from intertidal and nearshore marine ecosystem components and is located in an area of the channel characterised by plankton, pelagic marine species and soft seabed invertebrate communities.

The ecosystem components associated with the habitats are closely connected by their relatively close spatial proximity and the strong tidal currents that transport water back and forth through the channels and over and off the intertidal flats.

These characteristics contribute to the listing of a large part of Western Port as a Ramsar wetland of international significance and the allocation of distinct areas as National Parks. Many of the animal and plant species are not specifically protected or listed for conservation value, but the combination mangroves and seagrasses, saltmarsh, fish, birds, crustaceans, worms and other strange invertebrates all form the Western Port marine ecosystem that is valued by the public. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 7

Figure 2. Natural marine ecosystem components at Crib Point (Position of FSRU shown in red)

Figure 3. Conceptual model of Western Port marine ecosystem in Crib Point area AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 8

1.3 Purpose of this report The purpose of this assessment is to provide a review of marine environmental matters protected under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the State Flora and Fauna Guarantee Act 1988 (FFG Act) that may be affected by the Project. The report examines the impact pathways of the Project and assesses the associated risks to protected marine species.

This report has been prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), · A referral under the Victorian Environment Effects Act 1978, and · Identification of requirements under the Victorian Flora and Fauna Guarantee Act 1988 (FFG Act). The report is expected to inform the preparation of a works approval application to be submitted to the Environment Protection Authority under the Environment Protection Act 1970 and in accordance with the relevant associated regulations, including the State Environment Protection Policy (Waters of Victoria).

1.4 Scope The scope of this study was to review relevant Commonwealth and State legislation for marine protected areas, protected marine species (flora and fauna, excluding birds and terrestrial fauna) and listed processes that may be relevant to the Project.

Terrestrial flora and fauna and waterbird species are not within the scope of this assessment. These aspects are addressed in the Flora and Fauna Assessment Report (Jacobs, 2018a).

Information on protected matters have been compiled from various sources including State and Commonwealth government web sites and publications and information from other development projects in the region. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 9

2 LEGISLATIVE INSTRUMENTS The key legislative instruments that this Protected Matters report addresses for the purposes of informing marine ecosystem descriptions in referral documents are described below. These matters are relevant to impact assessment under the EPBC Act, the EE Act and FFG Act.

2.1 Commonwealth EPBC Act 1999 The Commonwealth EPBC Act is a wide ranging legislative instrument that provides legal protection of the environment, particularly those features of Australia’s environment, biodiversity and heritage that are listed matters of national environmental significance (MNES). The EPBC Act lists nine MNES and three of these are relevant to the Project:

· Wetlands of International Importance (listed under the Ramsar Convention) · Listed threatened species and ecological communities · Migratory species protected under international agreements

The Commonwealth Department of the Environment and Energy (DoEE) provides the Protected Matters Search Tool that facilitates searches of the Department’s database for MNES in the area of a development.

The Commonwealth provides Guidelines to determine whether an action (project) is likely to have a significant impact on a MNES (“Significant Impact Guidelines”) or whether an action constitutes a listed key threatening process, or entails processes known to be a threatening process for specific listed species or places.

2.2 Environment Effects Act 1978 The EE Act requires consideration to be given to projects which have significant impacts on the Victorian environment as described in the Act.

A project with potential adverse environmental effects that, individually or in combination, could be significant in a regional or State context should be referred. The criteria for referral are provided in the Ministerial Guidelines for Assessment of Environmental Effects under the Environment Effects Act 1978 (Ministerial Guidelines).

The Ministerial Guidelines include referral criteria for: · potential long-term change to the ecological character of a wetland listed under the Ramsar Convention or in ‘A Directory of Important Wetlands in Australia’ · potential extensive or major effects on the health or biodiversity of aquatic, estuarine or marine ecosystems over the long term · potential long-term loss of a significant proportion (e.g. to 1 to 5 percent depending on the conservation status of the species) of known remaining habitat or population of a threatened species within Victoria · matters listed under the FFG Act 1988 including:

- potential loss of a significant area of a listed ecological community; or

- potential loss of a genetically important population of an endangered or threatened species (listed or nominated for listing), including as a result of loss or fragmentation of habitats; or

- potential loss of critical habitat; or AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 10

- potential extensive or major effects on beneficial uses of waterbodies over the long term due to changes in water quality. · potential extensive or major effects on beneficial uses of waterbodies over the long term due to changes in water quality The Ministerial Guidelines provide guidance on the matters to be considered in determining the extent to which the Project is capable of having a significant effect on the environment.

2.3 Victorian FFG Act 1988 The Victorian FFG Act 1988 – sets out its objectives in section 1, Purpose: “The purpose of this Act is to establish a legal and administrative structure to enable and promote the conservation of Victoria's native flora and fauna and to provide for a choice of procedures which can be used for the conservation, management or control of flora and fauna and the management of potentially threatening processes.”

The processes to assess the Act objectives are to list threatened flora and fauna, ecological communities and threatening processes, as well as declare areas of “critical habitat” essential to the survival of flora or fauna taxa or ecological communities. The Department of Environment, Land, Water and Planning (DELWP) provides Action statements for individual taxa or communities using risk-based prioritisation.

Under the Act, a potentially threatening process “means a process which may have the capability to threaten the survival, abundance or evolutionary development of any taxon or community of flora or fauna”. A number of action statements have been prepared for key flora and fauna taxa. No areas of critical habitat have been declared under the Act.

A review of the listed species under the FFG Act (last updated March 2017) revealed that there are 25 listed species that may occur in the vicinity of the Project at Crib Point and one protected community (San Remo Marine Community, around 23 km from the Project Site). Furthermore, aspects of the Project involving the ongoing operation of the FSRU within the Port require management and mitigation in order to avoid FFG listed threatening processes: · Input of petroleum and related products into Victorian marine and estuarine environments; · The discharge of human-generated marine debris into Victorian marine or estuarine waters; and · The introduction of exotic organisms into Victorian marine waters. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 11

3 MARINE ENVIRONMENT PROTECTED MATTERS The DoEE Protected Matters Search Tool was used by CEE marine environmental scientists in September 2017 to list MNES within a 10 km radius of the Project Site at Crib Point, which includes all of North Arm of Western Port as well as the Western Entrance to Western Port (Figure 4).

Figure 4. Protected Matters Search area

In practise, the Search Tool includes species that may occur over a substantially wider area than the nominated search perimeter. Hence a 10 km search radius was considered to be a conservative area for potential extent of the Project impact pathways on the marine environment in the vicinity of Crib Point. The search Summary table from the EPBC Act Protected Matters Report relevant to the marine environment is reproduced in Table 2.

Table 2. Summary of marine Protected Environmental Matters within 10 km of Crib Point AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 12

The results of this search returned four marine matters of national environmental significance within a 10 km radius of Crib point: 1. One wetland of International Importance: the Western Port Ramsar site 2. Two listed threatened ecological communities 3. Almost 60 listed threatened species 4. More than 50 listed migratory species

CEE environmental scientists screened the listing to determine: the relevance of each listing to the marine environment (excluding waterbirds and waders) and; the likelihood of occurrence of the species or community within the search area. The screening assessment revealed that: 1. The listed threatened ecological communities were the terrestrial communities and not within the scope of the marine assessment; 2. The listed threatened species included terrestrial biota, various bird species including waterbirds, shorebirds, waders and oceanic albatrosses and petrels. Six of the threatened species were considered to be endangered or vulnerable ‘marine’ species for further assessment. 3. The listed migratory species included various bird species including waterbirds, shorebirds, waders and oceanic albatrosses and petrels. Twelve of the listed migratory species were considered to be migratory ‘marine’ species (excluding birds) protected under international agreements for further assessment in this document. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 13

4 WESTERN PORT RAMSAR SITE The Western Port Ramsar site was designated as a wetland of international significance in 1982. The Ramsar site covers 59,950 ha of Western Port including Crib Point (Figure 5). Western Port is one of eleven Victorian Ramsar sites and the third most important area for wading birds in Victoria. All Ramsar sites are MNES under the EPBC Act. Ramsar areas are wetlands of international importance to waterbirds in any season.

Figure 5. Western Port Ramsar site

The Convention on Wetlands of International Importance especially as Waterfowl Habitat is a treaty negotiated between 18 countries and a number of NGOs at Ramsar, Iran in 1971. Australia became a Contracting Party in 1974 and the Ramsar Convention as it is now known entered into force in 1975. The Ramsar Convention established the criteria for declaring a site a Wetland of International Importance, which now include nine criteria covering species, ecological communities, waterbirds, fish and other taxa. The Ramsar Convention encourages signatory countries to designate wetland sites in order to conserve AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 14 their ecological, botanical, zoological, limnological or hydrological importance. By listing a Ramsar site, countries agree to establish and oversee a management framework to conserve a wetland and ensure its wise use.

The current management plan for the Western Port Ramsar site was released by DELWP in 2017. The Western Port Ramsar site comprises a large area of shallow intertidal mudflats, deep channels and some narrow strips of coastal land. The site includes all areas of Western Port north of a line between Point Leo (Mornington Peninsula) and Observation Point (Phillip Island) and a line between Newhaven and San Remo (The Narrows).

Western Port meets seven of the nine criteria for designation as a Ramsar site, as reviewed by KBR (2010) and DELWP (2017), and listed in the Australian Wetlands Database: · Criterion 1: Western Port is a particularly good example of a natural wetland marine embayment with extensive intertidal flats, mangroves, saltmarsh, and seagrass beds within the South East Coastal Plain bioregion. Western Port is also a very good example of a saltmarsh-mangrove-seagrass wetland system. · Criterion 2: The site supports the fairy tern which is a species of global conservation significance, in addition to the dense leek-orchid which is listed as vulnerable under the EPBC Act. Saltmarsh vegetation within the site provides important habitat for the orange- bellied parrot, listed as critically endangered under the EPBC Act. · Criterion 3: Western Port is one of the most important areas for migratory waders in south-east Australia with wader surveys indicating that the Ramsar site supports up to 39 species, and includes 10 000 to 15 000 summer migrants (approximately 12 to 16 per cent of the Victorian population). It also supports seagrass and mangrove communities that are characteristic of the marine embayments of Southern Victoria. · Criterion 4: The Ramsar site is one of the three most important areas in southeast Australia for migratory waders in total numbers and density. The site also provides important overwintering habitat for the orange bellied parrot. It also provides a number of important high tide roosts and breeding habitat. · Criterion 5: The Ramsar site regularly supports about 10 000 to 15 000 migratory waders, and periodically supports 1000 to 3000 ducks and 5000 to 10 000 Black Swans. · Criterion 6: The Ramsar site regularly supports more than one per cent of the estimated flyway population of five wader species. The site also regularly supports internationally significant numbers of several non-wader species. · Criterion 7. Not considered applicable in KBR (2010) and DELWP (2017) reviews · Criterion 8: Seagrass beds within the Ramsar site are known to provide important nursery habitat for a number of fish species, including commercially significant species. · Criterion 9. Not considered applicable in KBR (2010) and DELWP (2017) reviews

In addition to fulfilling the majority of the Ramsar criteria for designation, Western Port contains a large number of Wetland Habitat types recognised under the Ramsar Convention. Wetland habitats include: · Marine subtidal aquatic beds; such as seagrass and algae beds, including near Crib Point · Rocky marine shores; such as the intertidal and subtidal rocky reefs · Estuarine Waters; such as the areas around the mouths of the rivers and creeks that drain into Western Port · Intertidal mud, sand or salt flats; such as the extensive vegetated and unvegetated mud and sand flats, including around Crib Point · Intertidal forested wetlands; such as the extensive fringing mangroves around the north and west shores of Western Port, including near Crib Point. The White Mangroves (Avicennia marina) found in Western Port are the most southerly mangroves in the world. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 15

· Intertidal marshes; such as the salt marshes behind the Mangroves in Western Port, including near Crib Point

The management plan for the Western Port Ramsar Site (DELWP, 2017) identified 17 priority threats to the values of Western Port as a Ramsar Site. Three of these threats are relevant to the Project: · Invasive species: introduced marine pests (current and potential new invasions) · Climate change: sea level rise · Climate change: increased frequency and intensity of storms leading to shoreline erosion · Climate change: increased frequency and intensity of storms leading to increased sediments

Industrial development resulting in habitat removal and associated impacts as well as emissions of toxicants from rural, agricultural and urban areas were also identified as priority threats. The Project does not involve removal of habitat within the Ramsar boundaries.

The management plan also identifies management strategies for protecting the Western Port Ramsar site. Those with most relevance to the Project are: · 3.6 Develop and implement a strategic approach to development in areas adjacent to the Ramsar site that consider the cumulative impact of multiple actions on ecological character · 3.14 Develop and implement a marine pest strategy for Western Port.

These two strategies have not yet been developed or published. An action statement on the introduction of exotic organisms into Victorian marine waters was produced under the FFG Act in 2004 and is discussed in section 5.5.1 of this report.

The high environmental, social and economic worth of Western Port is recognised further through the declaration of Western Port as an UNESCO Biosphere reserve and the presence of several Marine National Parks within the Ramsar site (Churchill Island, French Island, Yaringa, see Figure 6). AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 16

Figure 6. Marine National Parks within and adjacent to Western Port Ramsar site Crib Point Jetty circled red. Ramsar area bordered in black. Marine National Parks are blue areas. Terrestrial National Parks and reserves are green areas. (Source: “Western Port Ramsar site. Strategic management plan.” DSE 2003)

4.1 Areas important for waterbirds As discussed above, Criteria 3 to 6 of the nine criteria for designation as a Ramsar site directly relate to waterbirds, including wader and non-wader migratory and flyaway species.

The key areas used by waterbirds in the Western Port Ramsar area are shown in Figure 7. The figure shows that all of the intertidal mudflats of the Western Port Ramsar area are considered to be suitable foraging area for waterbirds. Primary foraging areas for waterbirds extends over the intertidal mudflats to the north of Crib Point, while mudflats to the south of Crib Point are rated as secondary foraging areas. The closest roosting sites are located more than 4 km from Crib Point at Long Island Point to the north, or across North Arm at Fairhaven on French Island. The next closest roosting site is located at Sandy Point more than 6 km south of Crib Point. Effects of the Project on waterbird species is assessed in the “Flora and Fauna Assessment Report” (Jacobs, 2018a). AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 17

Figure 7. Key roosting, feeding and breeding habitat for waterbirds in Western Port (Hansen, Menkhorst and Loyn 2011)

The most commonly identified threats to wading birds in Western Port were listed (Hansen et al 2011) as: · Habitat loss and modification · Disturbance from beach users (walkers, joggers, dog walkers, etc.) · Disturbance from water users (fishing, sailing, personal water craft and similar) · Nest loss (trampling, storm or tidal inundation) · Bird injury &/or mortality (predation, collision with vehicles or vessels, tangling in fishing line) · Competition · Aircraft activity. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 18

5 EPBC ACT AND FFG ACT MARINE PROTECTED SPECIES There are 33 threatened and migratory species listed under the EPBC Act and FFG Act that may occur in the vicinity of the Project at Crib Point, as shown in Table 3.

Table 3. Protected species in region of Crib Point Jetty (at September 2017) Common name Scientific name EPBC FFG Mammals Blue Whale Balaenoptera musculus Endangered, Migratory Listed Southern Right Whale Eubalaena australis Endangered, Migratory Listed Humpback Whale Megaptera novaeangliae Vulnerable, Migratory Listed Brydes Whale Balaenoptera edeni Migratory Pygmy Right Whale Caperea marginata Migratory Killer Whale Orcinus orca Migratory Dusky dolphin Lagenorhynchus obscurus Migratory Burrunan Dolphin Tursiops australis Listed marine (NA) Listed Sharks White shark Carcharodon carcharias Vulnerable, Migratory Listed Grey nurse shark Carcharius taurus Listed Mackerel Shark Lamna nasus Migratory Freshwater/Marine Migratory Fish Australian grayling Prototroctes maraena Vulnerable Listed Australian mudfish Neochanna cleaveri Listed Marine Fish Mugilogobius platynotus Mangrove Goby M paludis** Listed Southern Bluefin Tuna Thunnus maccoyii Listed Australian Whitebait Lovettia sealii Listed Reptiles Leatherback Turtle Dermochelys coriacea Endangered, Migratory Listed Loggerhead Turtle Caretta caretta Endangered, Migratory Green Turtle Chelonia mydas Vulnerable, Migratory Marine Invertebrates Southern hooded shrimp Athanopsis australis Listed Ghost shrimp Pseudocalliax tooradin Listed Ghost shrimp Michelea microphylla Listed Brittle star Amphiura triscacantha Listed Sea-cucumber Apsolidium densum Listed Sea-cucumber Apsolidium handrecki Listed Brittle star Ophiocomina australis Listed Sea-cucumber Pentocnus bursatus Listed Sea-cucumber Thyone nigra Listed Sea-cucumber Trochodota shepherdi Listed Chiton Bassethullia glypta Listed Opisthobranch Platydoris galbana Listed Opisthobranch Rhodope genus Listed Stalked Hydroid Ralpharia coccinea Listed * Pipefish and seahorses that occur in lists in the EPBC Act are not relevant to this project. The list applies only to Commonwealth waters and Commonwealth agency proponents. **Flatback or Pale mangrove goby is listed as Mugilogobius paludis in FFG, but is more correctly known as M platynotus

Each species listed under the EPBC Act or FFG Act is discussed below. Those species listed on both the EPBC Act and FFG Act are discussed first, followed by those species listed only on the FFG Act and not the EPBC Act. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 19

5.1 Endangered species The DoEE PMST identified that four endangered marine species may occur in the Western Port region: the Blue Whale, the Southern Right Whale, the Leatherback Turtle and the Loggerhead Turtle. Both whale species and the Leatherback Turtle are also listed under the FFG Act. Most of these species are unlikely to occur near Crib Point, except on very rare diversions from their regular migratory pathways. However, they are discussed below to thoroughly assess the potential impacts and demonstrate that that the Project at Crib Point presents negligible risk to these species.

5.1.1 Blue Whale The Project Site at Crib Point is remote from Blue Whale aggregation areas and plausible migration pathways. It is highly unlikely that Blue Whales would enter the North Arm of Western Port. Overall, it is highly unlikely that the processes associated with the Project would have any effect on Blue Whales. The nearest record is for a decayed specimen that washed up on Flinders Beach (whales often drift great distances at sea after death). There are records of sightings offshore from Cape Schanck and east of Wilsons Promontory, but none in the vicinity of Western Port.

Blue Whales are the largest of whales growing to 33 m in length, with an average size of 25 m. Research at Deakin University (Dr Peter Gill) has shown that there is a population of Blue Whales which is resident for the summer period in western Victorian waters (Figure 8).

This population of Blue Whales is slightly smaller than their northern hemisphere counterparts and is therefore sometimes referred to as ‘pygmy’ Blue Whale. This term tends to misrepresent the members of the southern Australian population whose size of 22 m is substantially larger than other whale species in the region such as the Southern Right Whale (17 m) and Humpback Whale (15 m).

The southern Australian population of Blue Whales feed on krill in western Victorian and eastern South Australian waters over summer (Figure 8). The migration path of this population has not been established. It may migrate eastward and up the east Australian coast with the Eden population to spend winter in areas of productive southern Pacific tropical seas, or westward and up the West Australian coast with the Rottnest population.

The south-eastern Australian population of Blue Whales is small in number (probably around 50 individuals). The worldwide number of Blue Whales is also very small and so the southern Australian population forms a significant proportion of the world’s total population. The migration paths of the south-eastern Australian population have not been documented. It is likely that some individuals may pass through central Bass Strait during autumn and spring migrations between the Portland region and the tropics, including past the entrances to Western Port. These large whales generally inhabit deeper, offshore waters and will pass a considerable distance offshore from the coastline, and it is highly unlikely that they would enter the relatively shallow waters of Western Port. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 20

Figure 8. Distribution of Blue Whales (Source: Blue, Fin and Sei, Whale Recovery Plan, DEWR)

5.1.2 Southern Right Whales Southern Right Whales are encountered seasonally in Bass Strait, more frequently in western Bass Strait where they calve and intermittently in central Bass Strait. Southern Right Whales may pass close to the shore all along the central Victorian region including past the entrances to Western Port. Southern Right Whales have been sighted in Western Port, with two records in the vicinity of Crib Point, but the bay is not known to be an aggregation or breeding area for these whales. The distribution and recognised aggregation areas of the Southern Right Whale is shown in Figure 9.

Southern Right Whales are large whales measuring up to 17.5 m. They migrate each year from summer feeding grounds in the subantarctic to calve and mate in warmer waters off the southern Australian coast during winter. Southern Right Whales were hunted to near extinction by the early 1900's, but the number has slowly recovered resulting in increasing numbers of sightings along parts of the southern Australian coastline during winter and spring. The Australian total population of Southern Right Whales is estimated to be 800. Since the 1970's Southern Right Whale sightings along the Victorian coast have increased significantly (Warneke 1995), but the trend has not been quantified. The actual number of whales visiting Victoria is a very small fraction of the main population which over-winters along the coasts of South Australia and Western Australia.

In Victoria, pregnant females generally arrive in May-June and depart with their calves in October-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. There is a major maternity site at Logans Beach, Warrnambool. Southern Right Whales may enter Western Port’s western entrance and are observed from vantage points and wildlife cruises along Phillip Island’s northwest, west and southern coast (Figure 13). AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 21

Figure 9. Distribution of Southern Right Whales (Source: Southern Right Whale Recovery Plan, DEWR)

5.1.3 Leatherback Turtle The Leatherback, Leathery, Luth or Trunkback Turtle (Dermochelys coriacea) is the largest of all the marine turtles and grows to 1.7 m long (carapace) and 600 kg. Leatherback Turtles pre-date other marine turtles by around 65 million years, they have inhabited the oceans for around 100 million years. The Leatherback Turtle is migratory and has a worldwide distribution in tropical, temperate and sub-polar waters down to 10°C. The Leatherback Turtle is listed as critically endangered under the Victorian FFG Act.

Adults live in ocean habitats and rarely come close to shore in Australia. Breeding occurs on tropical islands throughout the world. Leatherbacks found around Australia are understood to breed in the islands of Indonesia, Papua New Guinea, Torres Strait and Arnhem Land. The species is migratory, travelling thousands of kilometres between breeding and foraging areas. Leatherback Turtles feed mostly on pelagic invertebrates such as jellyfish and Bass Straight has one of the three largest concentrations of feeding Leathery Turtles in Australia. In Victoria, Leatherback Turtles are most commonly seen between April and May, when the waters of Bass Strait are warmest. Sightings and strandings have been recorded all along the Victorian Bass open coast, Port Philip Bay and the Gippsland Lakes (Figure 10). There are no records from Western Port, however there have been numerous sightings nearby, including around Port Phillip Heads.

The Leatherback Turtle is considered critically endangered worldwide, vulnerable under the EPBC Act and critically endangered in Victoria (DSE, 2007), though it is listed as threatened under the FFG Act. The key threat to the species, as for many turtles, is human disturbance of breeding habitats and harvesting of eggs. Leatherback Turtles do not nest in Victoria. Other threats include by-catch in commercial fisheries, and in Victoria the key by-catch threat is entanglement in cray pot buoy lines. Ingestion of marine debris is also a concern, AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 22 particularly of plastics, as Leathery Turtles tend to feed along drift lines where debris accumulates.

Figure 10. Sightings of Leatherback Turtles in Victoria (DSE, 2007)

5.1.4 Loggerhead Turtle The Loggerhead Turtle (Caretta caretta) is smaller than the Leatherback Turtle at around 1 m carapace length. They inhabit primarily tropical and subtropical seas, though it is thought likely they occasionally occur in south-east Australia in the warmer months. Loggerhead Turtles are carnivorous, feeding on crabs, sea-urchins and jellyfish. There are two distinct populations in Australia, one which nests along the northwest coast of Western Australia and one that nests on islands and coasts of the southern Great Barrier Reef. Nesting does not occur in Victoria.

The key threats to Loggerhead Turtles are similar to those for Leatherback Turtles – they include threats to nesting success and commercial fishery by-catch mortality. Predation of eggs by foxes on mainland beaches is a key problem in Western Australia and Queensland. Mortality as fishery by-catch is a problem throughout their tropical and sub-tropical foraging range, with entanglement in lobster-pot buoy lines, long lines, and ghost nets the key issues.

There are 13 records of Loggerhead Turtles in Victoria (Atlas of Living Australia, 2017), the majority of which were recorded on the Victorian coastline west of Melbourne (Figure 11). Seven were of dead specimens and most others were live beach strandings. There are no records from Western Port. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 23

Figure 11. Turtle sightings in Southeastern Australia (https://cie-deakin.com/about-sast/)

5.2 Vulnerable species The DoEE PMST identified four vulnerable marine species that may occur in the Western Port region: Humpback Whales; Great White Shark, Australian Grayling and Green Turtle. The Humpback Whale, Great White Shark and Australian Grayling are also listed under the FFG Act.

5.2.1 Humpback Whales Humpback Whales are large whales growing to approximately 18 m and have a worldwide distribution. Central Bass Strait including Western Port is generally outside Humpback Whales’ migratory path, and is not a feeding, breeding or calving area (Figure 12). However, humpback whales migrating up the western side of Tasmania and then eastward through Bass Strait may wander from their migratory path into Western Port from time to time, and there are records of Humpback Whales in Western Port as far north as Crawfish Rock (ALA, 2017). Whale records collated for the Two Bays Project (Figure 13) show that, a total of 175 humpback whales were sighted in winter close to Phillip Island since records commenced in 2002. Considering the small number of Humpback whales that may occur in the area, the extremely small proportion of the population that those individuals represent and the low likelihood of interaction with the Project, the risk to these whales is very low. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 24

Figure 12. Distribution of Humpback Whales (Source: Humpback Whale Recovery Plan, DEH)

Figure 13. Whale sightings compiled for Two Bays Project 2014 to 2017 (Source: Victorian Dolphin Research Institute and Wildlife Coast Cruises) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 25

5.2.2 White Shark The key threats to White Shark (also known as Great White Shark) populations are commercial fishing, recreational fishing, shark control activities (beach meshing), trade (fins, jaws and teeth) and tourism (FFG Action Statement No. 185). The Project does not involve these threats, and it is unlikely that indirect effects of the development will detrimentally affect White Shark populations.

The White Shark is a very large shark. It occurs in all oceans of the world, including Bass Strait and Western Port. The seal breeding colony at Seal Rock at the Western Entrance to Western Port is a known feeding area for White Sharks and these sharks have been caught and observed in Western Port from time to time.

White Sharks are highly mobile with vast individual geographic ranges. Individuals typically remain resident in one locality only for periods of days or rarely weeks before moving to another area, according to observations of fishermen, divers and marine scientists. The breeding characteristics of whites is not known with “only two pregnant females recorded in contemporary times” (Last and Stevens 1994). White Sharks have been tagged with transmitters by various researchers including CSIRO. A shark (Neale) that was tagged near Corner Inlet in eastern Bass Strait travelled a total of 3,000 km over a 4 month period. The track included two Bass Strait crossings – probably east of Flinders Island – in the general region of Western Port. Neale’s track concluded at Coffs Harbour in New South Wales. Other sharks have been tracked making repeat crossings of the Tasman Sea to New Zealand, and up and down the West and East Australian coasts. The risk to White Shark populations from the development and operation of the Project is considered to be negligible.

5.2.3 Australian Grayling The Australian Grayling (Prototroctes maraena) is a small (300 mm long) freshwater fish that has larval and juvenile stages in the marine environment. The Bass River in south-eastern Western Port and the Bunyip River in north-eastern Western Port are the two most significant freshwater inputs to the Bay.

The population of the Australian Grayling 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, Tasmania and on King Island in Bass Strait. In Victoria, Grayling are known to occur in most permanent rivers and streams with natural flow regimes, as well as rivers and streams with modified flow regimes (eg. Yarra, Barwon, Bunyip) and varying water quality. Large populations may occur in rivers in eastern Victoria such as the Tambo River. There appears to be some mixing between larval populations during their marine phase (Crook et al, 2006).

Studies have identified that in streams with modified flow regimes, such as the Bunyip River, provision of environmental flows timed to trigger spawning of Australian Grayling is likely to improve their populations (DELWP, 2016).

It is possible that larvae and juvenile Grayling disperse and migrate between freshwater streams in Western Port and Bass Strait via North Arm and the Western Entrance to Western Port. The importance of these pathways to the local Grayling populations is uncertain. The intake of seawater through the Crib Point regasification facility may entrain dispersing larvae and migrating juveniles and therefore may be considered to be a ‘barrier to migration’ (FFG Action Statement no. 257). Cold water and dilute biocide in the seawater discharged from the heat exchange system may also provide a thermal and chemical barrier for migrating juveniles and dispersing larvae. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 26

The potential effects of these Project impact pathways is assessed in Section 6 of this report.

5.2.4 Green Turtle The Green Turtle (Chelonia mydas) is a tropical species of turtle, and one of the most numerous of the seven turtle species found globally. It generally only occurs in waters where temperatures average 20°C or more, but may occasionally stray into temperate waters (following warm coastal currents) given its long migration ability. Their preferred habitat is coral reefs with abundant algae and seagrass beds, and adults are herbivorous. There are seven nesting populations in Australia, with all nesting occurring in tropical waters – from the southern Great Barrier Reef, around the Top End to the North West Shelf.

There are seven records of Green Turtles in Victorian waters, most of them for dead specimens found on beaches. There is one record of a dead Green Turtle on Reef Island in eastern Western Port.

Threats to the Green Turtle primarily relate to disturbance of nesting and foraging sites, collisions with boats and ships, habitat disturbance and by-catch in fishing operations.

5.3 Migratory species The DoEE PMST identified that eight migratory marine species may occur in the Western Port region: The Blue Whale, Southern Right Whale, Humpback Whale, Bryde’s Whale, Pygmy Right Whale, Dusky Dolphin, Killer Whale, White Shark and Mackerel Shark. In addition, three turtle species may occur in the Western Port region and are protected under the EPBC Act. Seven of these species are discussed in the preceding sections as they are also listed as endangered or vulnerable. The remaining five species are discussed below with reference to records in the Atlas of Living Australia.

5.3.1 Brydes Whale Bryde’s Whale is a large whale which grows to approximately 15 m and feeds on schooling fish such as anchovies and pilchards. It is generally confined to tropical and temperate waters from the equator to 40o north and south of the equator. In Australia it is mostly recorded from northern Western Australian waters and off Queensland. It is unlikely to occur frequently along the southern Australian coastline or in Bass Strait. There are no records of Brydes Whales in Western Port or Victorian waters.

5.3.2 Pygmy Right Whale The Pygmy Right Whale is a small, planktivorous whale which grows to approximately 6.5 m length. It is widely distributed in the southern hemisphere. Pygmy Right Whales may be common in Bass Strait from time to time although they do not appear to follow seasonal migrations. There are a small number of observations near Warrnambool in Western Victoria, but none elsewhere in Victoria. There do not appear to be any significant breeding or feeding grounds for Pygmy Right Whales in the Western Port. A skull from the species was found near Cowes on Phillip Island.

5.3.3 Dusky Dolphin The Dusky Dolphin is a relatively small dolphin that occurs in the southern hemisphere in cool waters from 26o S to 55o S. They may migrate southward in summer. There are no records of Dusky Dolphins in Victorian waters and there does not appear to be any significant breeding or feeding grounds for Dusky Dolphins in the Western Port area. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 27

5.3.4 Killer whale The Killer Whale is a moderate sized, predatory whale that is distributed throughout the oceans of the world. Small pods of Killer Whales are observed in Bass Strait from time to time including the area offshore from Western Port, particularly around Seal Rocks. There is one recorded sighting inside Western Port off Ventnor on Phillip Island.

Killer Whales eat a wide range of marine species including seals and penguins. It is not known whether Killer Whales are attracted to the breeding colonies of penguins and seals at Phillip Island, but they have been recorded at and near Seal Rocks by the Two Bays Project (Figure 13).

5.3.5 Mackerel Shark The Mackerel Shark or Porbeagle (Lamna nasus) is a medium sized (up to 2 m and 230 kg) found throughout temperate seas around the world and in Australia from southern Queensland to southwest Australia. It primarily inhabits waters near the continental shelf where it feeds on pelagic fish and cephalopods (squid). The key threat to the Mackerel Shark is overfishing due to the high value of its fins, long life-span and low fecundity. It is prohibited to target Mackerel Sharks in Australian waters. The Mackerel Shark may occasionally, and temporarily enter coastal waters. There are no records from Victorian Coastal Waters or Bass Strait.

5.4 Additional FFG Act listings 5.4.1 Grey Nurse Shark Grey Nurse Sharks are most unlikely to be found in the central Bass Strait region or in Western Port.

The Grey Nurse Shark is listed as vulnerable under the EPBC Act, with the east coast population being listed as critically endangered. The Grey Nurse Shark is listed under the FFG Act. There are no recent confirmed records of Grey Nurse Sharks in Victoria south of Mallacoota. The distribution of Grey Nurse Sharks (western and eastern populations) in Australia is widely considered to be confined to Western Australia, southern Queensland and the entire New South Wales coast (DoEE, 2014).

The key threats to the species relate to recreational and commercial fishing and shark netting of bathing beaches (FFG Action Statement no. 186).

5.4.2 Southern Bluefin Tuna Southern Bluefin Tuna are most unlikely to be found in central Bass Strait or in Western Port.

This oceanic species 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. Hence, in Victoria, they are only found in western and eastern Victoria where the continental shelf is narrow. The key threat to Southern Bluefin Tuna is commercial fishing (FFG Action Statement no. 197). Protection of this species in Victoria is managed by setting a commercial by-catch limit of 0 kg, and restricting recreational anglers to a bag limit of two fish.

5.4.3 Australian or Tasmanian Whitebait The Australian Whitebait is a small (77 mm maximum length) fish which lacks scales and has translucent or silvery colouring, though adults may turn completely black in estuaries following spawning. Originally the fish was only known from Tasmania where it remains a AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 28 popular recreational fishing species in north coast estuaries. In Victoria (and the rest of mainland Australia) it has only been identified in the Tarwin River and Anderson Inlet, despite extensive sampling for fish in estuaries and inlets elsewhere in Victoria.

The Australian Whitebait was heavily fished commercially in Tasmania during the 20th century. The Tasmanian commercial fishery was closed in 1974 after it collapsed, and only limited, seasonal recreational fishing is now allowed. No commercial or recreational Australian Whitebait fishing has occurred in Victoria.

The key threats to the species in Victoria have been identified as by-catch during commercial glass eel fishing, impacts on fresh and estuarine water quality from runoff (pesticides, herbicides, fertilisers), oil spills and modification of habitat through the construction of marinas, dredging or stream modification (FFG Action Statement No. 259).

5.4.4 Australian Mudfish The Australian Mudfish is a small, 80 mm long fish associated with coastal wetlands and streams. Larvae and juveniles of the mudfish are thought to spend some time in marine waters before migrating back into streams and wetlands. Only 29 adult specimens have been identified from seven sites in Victoria, ranging from the east side of Wilsons Promontory to rivers west of Cape Otway. None have been identified in Western Port, though suitable habitat may exist. The key threat to the population of Australian Mudfish in Victoria is the loss of suitable wetland habitat due to human modification, particularly in South Gippsland (FFG Action Statement No. 115).

5.4.5 Pale or flatback mangrove goby The FFG Act lists the pale mangrove goby Mugilogobius paludis (Whitley,1930) as a threatened species in Victoria. Consultation with Curator of Fishes at Museums Victoria revealed that M paludis is the same species at M platynotus. Further, M platynotus (Gunther 1861) is the correct identification for the species as determined in the taxonomic literature (Larson 2001). M platynotus is known as the flatback mangrove goby, mangrove goby and pale mangrove goby.

Figure 14. Distribution of flatback mangrove goby (Mugilogobius platynotus) (http://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon accessed September 2017) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 29

The flatback mangrove goby is a small brown goby found in mangrove associated marine and estuarine bays and inlets from southeast Queensland to Victoria (Figure 14). M platynotus is known also to be widespread in Western Port (Figure 14), whereas M paludis is known only from one individual collected on unvegetated mudflat at Wooleys Beach near Crib Point in 2002 (Hindell and Jenkins 2003, Jenkins 2015). The record of M paludis should have been reported as M platynotus. The potential impact of the project on M paludism/platynotus is assessed in Section 6.5.1 of this report.

5.4.6 Marine Invertebrates Thirteen marine invertebrates are listed under the FFG Act, including three species of crustacean, seven species of echinoderm, three species of mollusc and one cnidarian (hydroid). The location of specimens, and the environment and habitat of these esoteric marine species are described in O’Hara and Barmby (2000), and are summarised in Table 4.

Table 4. Flora and Fauna Guarantee Act 1988 - listed marine invertebrates Taxa Common Name Environment Habitat Location Crustaceans Athanopsis Southern Bay Sand, mud, reef (5-12 Port Phillip Bay and australis hooded shrimp m) Bridgewater Bay (Vic) Pseudocalliax Ghost shrimp Bay Fine sand (2-5m) Swan Bay and Crib tooradin Point (Western Port) (Vic) Michelea Ghost shrimp Bay Sandy gravel (19 m) Crib Point (Western microphylla Port) (Vic) Echinoderms Amphiura Brittle star Bay and Posidonia and Nooramunga and triscacantha species Channel Heterozostera possibly Western Port seagrass beds (Vic) and Spencer & St (subtidal) Vincent Gulfs (SA). Apsolidium Sea-cucumber Open Coast Rocky shallows (0- Apollo Bay and densum species 2 m) Flinders (Vic) Apsolidium Sea-cucumber Bay Rocky shallows (on Merricks (Vic), Arno handrecki species rock platforms) Bay (SA) and Trigg Island (WA) Ophiocomina Brittle star Channel Posidonia and Nooramunga (Vic) and australis species Heterozostera Spencer & St Vincent seagrass beds and on Gulfs (SA) Pinna bivalves (subtidal) Pentocnus Sea-cucumber Open Coast Found living on Cape Paterson (Vic), bursatus species shallow water Beachport (SA) and macroalgae (subtidal) Cockburn Sound (WA) Thyone nigra Sea-cucumber Bay Bay habitats Corio Bay (Vic), St species (subtidal) Vincent Gulf (SA) and Bramble Pt, Princess Royal Harbour (WA) Trochodota Sea-cucumber Channel Posidonia seagrass Nooramunga (Vic) and shepherdi species beds (subtidal) Spencer & St Vincent Gulfs (SA) Molluscs Bassethullia Chiton Bay and Under rocks in sand Southern Port Phillip glypta Open Coast (intertidal to 10 m) Bay, Bass Strait (Port Phillip Heads), Flinders (Vic) and Stanley (Tas) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 30

Taxa Common Name Environment Habitat Location Platydoris Opisthobranch Bay Reef flat San Remo (Vic) galbana Rhodope genus Opisthobranch Bay Reef flat San Remo (Vic) Cnidarians Ralpharia Stalked Hydroid Bay Reef Crawfish Rock coccinea

Many of the marine invertebrates listed under the FFG Act are apparently Victorian endemic species (that is, only found in Victoria) and little is known about their biology (O’Hara and Barmby, 2000). These marine invertebrates are only known from between one and seven individual specimens which have been collected at between one and four different localities in Victorian waters.

Table 4 shows that eight listed species may occur in the general Western Port region, with two species of ghost shrimp found at Crib Point (“Pseudocalliax tooradin and Michelea microphylla). Five species are known from collections at locations in Western Port that are relatively remote from the direct activities associated with the Project. One species record (the brittle star Amphiura triscacantha) appears to have been a mis-identification. The eight species with recorded distributions in Western Port are discussed below.

The Western Port ghost shrimp Pseudocalliax tooradin (variously known as Callianassa tooradin 1979, Calliax tooradin Sakai 1988, Paraglypturus tooradin Turkay and Sakai 1995, Eucalliax tooradin O’Hara and Barmby 2000 and now Pseudocalliax tooradin Sakai 2011) and is known only from a total of less than 10 individuals. Four were collected subtidally in grab samples offshore from Crib Point in 1965 and since then have not been recorded in Western Port (Figure 15). The habitat where it was found at Crib Point comprised shallow, subtidal fine sand. It was also found in Swan Bay, a primarily shallow seagrass ecosystem. Its potential dependence on seagrass is not known. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 31

Figure 15. Distribution of Western Port ghost shrimp Pseudocalliax tooradin (From O’Hara and Barmby 2000) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 32

The ghost shrimp Michelea microphylla is known from only one specimen collected in sandy gravel in 19 m water depth offshore from Crib Point in 1965 (Figure 16). It is very rare as it has not been found anywhere else since 1965, including the comprehensive sampling program for the Western Port study in the 1970s (Coleman et al, 1978).

Figure 16. Distribution of ghost shrimp Michelia microphylla (From O’Hara and Barmby 2000) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 33

O’Hara and Barmby (2000) consider that the record of the brittle star Amphiura triscacantha from Western Port (Figure 17) is likely to be a mis-identification of another species, and that the species is likely to be confined to Posidonia seagrass beds in Corner Inlet and the South Australian Gulfs.

Figure 17. Distribution of brittle star (Amphiura triscacantha) (From O’Hara and Barmby 2000) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 34

The sea cucumber Apsolidium densum is known from only three individuals at Apollo Bay and one outside Western Port at Flinders (Figure 18). All four individuals collected were from rocky, wave exposed, intertidal habitats.

Figure 18. Distribution of the sea cucumber (Apsolidium densum) (From O’Hara and Barmby 2000) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 35

The sea cucumber Apsolidium handrecki is known from three separate locations in Victoria, South Australia and Western Australia. At all locations, the sea cucumber was found in rocky, intertidal habitats. The six specimens from Victoria were restricted to small rock platforms at Merricks, in the western arm of Western Port (O’Hara and Barmby 2000).

Figure 19. Distribution of the sea cucumber Apsolidium handrecki in Victoria (From O’Hara and Barmby 2000) AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 36

The chiton Bassethullia glypta is restricted to the central Victorian coast at the entrance to Port Phillip and Flinders near the entrance to Western Port and possibly at Stanley on the northwest coast of Tasmania (O’Hara and Barmby, 2000) (Figure 20). It is found under rocks in clean sand associated with high currents or wave exposed environments from the intertidal zone to 10 m water depth.

Figure 20. Distribution of the chiton (Bassethullia glypta) in Victoria (From O’Hara and Barmby 2000)

Two nudibranchs (Platydoris galbanus and the genus Rhodope) from San Remo are listed under the FFG Act, as well as the ‘San Remo Marine Community’ (see below).

The Hydroid species Ralpharia coccinea has only been found growing epizoically on the soft coral Parerythropodium membranaceum (Watson, 2015) at Crawfish Rock, at the top of North Arm, Western Port. It is similar to the more common species Ralpharia magnifica that also commonly grows on Parerythropodium membranaceum. Observations over many years on Western Port jetties have not revealed the presence of either hydroid species on jetty piles (CEE, 2016). AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 37

5.4.7 San Remo Marine Community The ‘San Remo Marine Community’ listed in the FFG Act is located just north of the Phillip Island Road bridge across the Narrows, near the eastern entrance to Western Port. It is around 23 km from Crib Point. The San Remo Marine Community was listed under the FFG Act due to the particularly high abundance and diversity of opisthobranch taxa (Nudibranch molluscs) in the 18 ha area that extends across an intertidal rock platform to the edge of the channel. Two opisthobranch taxa are listed individually on the FFG (Platydoris galbanus, Rhodope sp.) and a number of species are expected to be listed once they are described.

The San Remo Marine Community was listed under the FFG Act to protect it from coastal and marine development inconsistent with its survival (such as a marina proposed for the site). Identified threats include (FFG Action Statement No. 18): loss of all or part of the community due to dredging, invasion of the site by other species after physical disturbance, sedimentation from nearby dredging, changes to currents due to construction of breakwaters, and changes to water quality. The community was listed primarily to protect it from incompatible developments in the local area.

The effects of the Project are likely to be restricted within North Arm of Western Port. Hence, the San Remo Marine Community, located more than 16 km from North Arm is most unlikely to be affected by the Project.

5.5 EPBC Act threatening processes Two threatening processes affecting marine species are listed under the EPBC Act: · Loss of climatic habitat caused by anthropogenic emissions of greenhouse gases; and, · Injury and fatality to vertebrate marine life caused by ingestion of, or entanglement in, harmful marine debris.

Listed Threatening Processes listed under the EPBC Act are not matters of environmental significance, they are intended to provide official recognition of threatening processes and raise awareness of the significance of these threats to national biodiversity.

The Commonwealth Minister for the Environment and Energy may decide that a threat abatement plan is appropriate. In the case of climate change, the Threatened Species Scientific Committee advised the Minister that given that the Commonwealth, State and Territory governments have other greenhouse gas emission abatement plans in place, that a threat abatement plan under the EPBC Act was not appropriate (Threatened Species Scientific Committee, 2001). Nevertheless, the Project’s contribution to climate change impacts on marine environments was assessed – refer to the Greenhouse Gas Emissions Assessment Report (Jacobs, 2018b).

The Threatened Species Scientific Committee advised the Minister on a threat abatement plan for marine debris, which is presently being revised. The Project does not entail the creation of marine debris, assuming activities accord with State, Commonwealth and international regulations for waste management in marine environments.

Aspects of the Project, could potentially result in threatening processes listed under the FFG Act, such as: · Input of petroleum and related products into Victorian marine and estuarine environments · The discharge of human-generated marine debris into Victorian marine or estuarine waters · The introduction of exotic organisms into Victorian marine waters AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 38

The FFG Act listed potentially threatening processes should be managed using an appropriately designed and implemented Environmental Management Plan and operational controls which adhere to regulatory requirements regarding bilgewater, management of fuels and waste. An action statement has been prepared for the threat of the introduction of exotic organisms into Victorian Waters (FFG Action Statement No. 100). The threat of introduction of exotic marine species is discussed further below.

5.5.1 Introduced marine species The anthropogenic translocation and establishment of non-indigenous marine species (NIMS) is considered to pose one of the greatest threats to marine biodiversity, as well as more specific environmental, economic and human health impacts. The coasts of Australia have proven to be particularly vulnerable to invasions of exotic marine species, and a recent assessment reports the number of introduced and cryptogenic marine species in Australia to be 429 (Hewitt and Campbell, 2008). Temperate harbours and embayments on the southern coasts are particularly vulnerable having been colonised by numerous species from temperate marine environments in the northern hemisphere, particularly the north-west Pacific and the Mediterranean/north-east Atlantic regions. While many of the exotic species now established in Australian waters are relatively benign in terms of impact, a number of species are perceived to have caused significant impact and are considered to be invasive marine pests. These include the Northern Pacific seastar (Asterias amurensis), the Japanese kelp (Undaria pinnatifida), the European shore crab (Carcinus maenas), and the Mediterranean fan worm (Sabella spallanzanii).

Shipping and other maritime vessel traffic is one of the most significant vectors for both the primary introduction and secondary dispersal of non-indigenous species. Ports, or the waters in the vicinity of ports, are therefore often “hot spots” for NIMS, and both ships’ ballast water discharge and hull biofouling (particularly sea-chests) are recognised as vectors for marine pest incursions. Once a pest becomes established in one port, this port can then become a source for secondary dispersal to nearby environments by natural means or to other domestic ports, marinas or harbours by maritime traffic. In Victoria this has occurred with both Asterias amurensis and Undaria pinnatifida – which have since been detected at various locations outside Port Phillip Bay.

The risk posed by maritime traffic depends largely on the type of vessel or ship. Those that spend large amounts of time in port, such as bulk carriers, barges and drilling rigs, mean NIMS have more opportunity to colonise the vessel or disperse from it. Those that spend little time in port, such as container ships, pose a lower threat. Older vessels pose a greater threat as they are less likely to have good antifouling or effective ballast water management systems (to minimise the likelihood of translocating pests), while newer ships increasingly have effective ballast water management systems and good antifouling.

Going back a decade or so, a national port baseline survey program was undertaken to determine the marine pest status of Australia’s waters, and 35 ports around Australia were surveyed. As part of this program, the Port of Hastings (including Crib Point) was surveyed in 1997 (Currie and Crookes, 1997), along with three other Victorian ports: Portland (Parry et al 1997), Geelong (Curry et al, 1998) and Melbourne (Cohen et al, 2001).

In addition to determining the pest status in the surveyed ports, these surveys formed the basis for assessment of ballast water uptake and discharge risk associated with domestic ship voyages. A more general survey on marine pests in Western Port was undertaken in 2000 (Cohen et al, 2000). This latter survey did not follow the structured sampling protocols prescribed for the port surveys (Hewitt and Martin, 1996) but, instead, employed qualitative survey techniques to enable the survey of regions throughout Western Port, although there AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 39 was still an emphasis on areas considered susceptible to infestation, such as marinas and aquaculture sites.

5.5.1.1 The Marine Pest Status of Western Port During the 1997 baseline survey of the Port of Hastings, a total of 355 species were collected. Only seven of these were confirmed as introduced species: · the European green crab Carcinus maenus; · the European clam Varicorbula gibba (as Corbula gibba); · the Asian bag mussel Musculista senhousia; · the Asian bivalve Theora lubrica; and · three cosmopolitan bryozoan species: Bugula dentata; Bugula neritina; and Watersipora subtorquata.

For comparison, nine exotic species were detected in the baseline port survey of Portland, 20 in Geelong, and 37 exotic or cryptogenic species in Melbourne. Bugula dentata was the only species considered abundant enough within the Port of Hastings to cause significant ecological impact, as its erect flexible growths were found on the surfaces of pier pylons of all commercial wharves. However, this species has since been reconsidered to be native (Hewitt et al, 1999), with a widespread distribution in the Indo-Pacific.

The 2000 survey of marine pests in Western Port increased the number of recorded exotic species in the bay to 14 (Cohen et al, 2000). Species additional to those in the 1997 port survey were: · Four species of ascidians o Ascidiella aspersa, Ciona intestinalis, Styela plicata and Styela clava, · the Mediterranean fanworm Sabella spallanzanii, · the bivalve Crassostrea gigas; and · two green algal species o Codium fragile subsp. fragile and Ulva lactuca.

Only the crab Carcinus maenas appeared to be widely distributed in the bay in 2000, with the remainder apparently limited in their distribution. Sabella spallanzanii and Styela clava were found on mussel ropes transferred to Flinders from Port Phillip Bay, but were not found on the nearby Flinders Pier or on the sea floor below the mussel farms.

A single occurrence of the Japanese kelp Undaria pinnatifida in Western Port is known from near Flinders Pier (G. Parry, pers comm.). These plants were removed and there were no further findings in subsequent monitoring of the site.

In late 2007 several juvenile New Zealand green-lipped mussels (Perna canaliculus) were found in the sea chests of one of the vessels that voyages between Port Kembla and Hastings when it was dry-docked for routine maintenance (Lewis pers. obs.). Although follow up searches found no mussels near the relevant wharf at Hastings, the finding demonstrates a potential pathway for marine pest introduction to Western Port.

None of the large pests found in Port Phillip Bay (U. pinnatifida, A. amurensis, S. spallanzanii) have ever been observed during the BlueScope marine biological monitoring program (MSE, 2009) or biological monitoring of the Crib Point, Long Island Point or BlueScope jetties (Bok et al, 2017). However, since the last marine pest surveys in 2000, no targeted marine pest survey has been conducted in Western Port. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 40

5.5.1.2 Marine Pest Management Arrangements The environmental and economic threat posed by marine pests to Western Port is recognised by the Port of Hastings Development Authority (PoHDA) and Parks Victoria. The PoHDA prohibits in-water cleaning of ship hulls and propellers. The discharge of ballast waters is prohibited in port waters (PoHDA, 2017). Parks Victoria manages the three Marine National Parks which protect representative areas of Victoria’s marine biodiversity, and has identified marine pests as one of the major threats to the biodiversity of the parks.

Responsibility for the regulation of ballast water in Australia now lies with the Commonwealth. In 2016 the Commonwealth Biosecurity Act 2015 came into force and this enabled Australia to ratify the International Maritime Organization (IMO) Ballast Water Management Convention, which came into force on 8 September 2017. Ships in Australian waters will now have to manage ballast water according to the Australian Ballast Water Management Requirements which align with the International Convention for the Control and Management of Ships Ballast Water and Sediments 2004. The Biosecurity Act 2015 currently covers ballast water, but does not deal with the issue of biofouling, which is widely recognised as posing a similar or greater risk of introducing marine species to Australian waters.

A major review of Australia’s marine pest management arrangements was undertaken in 2014-15 (DAWR, 2015). The review made a number of recommendations for improving the way Australia prevents, eradicates and manages the introduction of marine species in Australia. One of the key recommendations was that Australia introduce new biofouling regulations consistent with International Maritime Organisation Biofouling Guidelines. A revision of a 2011 biofouling regulation impact statement is currently in preparation, with consultation expected to start in early 2018 (DAWR, 2018).

Currently, biofouling risks are managed through the National Biofouling Management Guidelines (Commercial Vessels, 2009) and Anti-Fouling and In-Water Cleaning Guidelines (2015).

The contribution of the development to marine pest risks in Western Port will require management under present Port, State and Commonwealth regulations. Issues related to specific aspects of the FSRU, such as development of hull fouling and cleaning, will be addressed in subsequent stages of the project assessment. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 41

6 PRELIMINARY ASSESSMENT OF PROJECT EFFECTS This section assesses the potential for project specific processes to affect MNES and FFG listed species that may occur in the vicinity of the Crib Point Jetty and the operation of the FSRU.

6.1 Project processes and potential impact pathways The potential impact pathways of the inclusion of the AGL Gas Import Jetty Project to the normal operations of the Port of Hastings can be divided into three categories:

(1) Shipping berthing, departing, loading and unloading operations in the working Port of Hastings, maintenance and minor improvement works associated with the jetty, jetty access, navigation, security and administration, (2) Upgrades to the existing Port infrastructure at Crib Point Jetty that will be required for the mooring of the FSRU and LNG carriers and the unloading and transfer of LNG and high pressure natural gas (as part of the Jetty Upgrade project), and (3) Operation of the heat exchange seawater intake and discharge associated with the regasification of LNG on-board the FSRU.

The category 1 impacts pathways are a consequence of the normal operation of the Port of Hastings. The Port of Hastings is operated by the PoHDA. PoHDA is responsible for environmental management of its own facilities and the general environmental management of ship-based activities (including the FSRU) within the Port boundaries. The operation of the Project will be subject to these existing operational environmental requirements and therefore has not been assessed further in this report.

The category 2 impact pathways are associated with the Jetty Upgrade, being undertaken by the PoHDA. The proposed upgrades have been subject to an environmental risk assessment (Jacobs, 2018c) and subsequently a draft Environmental Management Plan has been prepared for the construction activities. Category 2 impact pathways have not been assessed further in this report.

This assessment addresses the category 3 impact pathways − potential marine environmental impact pathways from the operation of the heat exchange system on-board the FSRU. The regulation of these impacts by EPA or DELWP will be determined in consultation with those agencies.

The impact pathways associated with regasification process on board the FSRU are listed below. · Intake of up to 450,000 m3 of seawater per day (0.29% the volume of the MCG) for heating of cold, liquid natural gas (LNG at -162oC) as part of the regasification process o A range of small marine and some large biota (including fish, diving seabirds such as penguins, cormorants and gannets and mammals such as seals and native water rats) may be drawn into the heat exchange system from the surrounding water column (or seabed) in the intake current to the seawater pumps and heat exchange pipework of the regasification facility on the FSRU o Large biota may be caught and damaged or drowned on screens at intake o Small biota may pass through screens and suffer further damage in the pumps and pipework of the heat exchangers. o In addition to the mechanical damage and injury to biota, smaller biota that survive the passage through the pumps will be exposed to cold water (up to 7oC below ambient and chlorine derived biocide, which is intended prevent biological growth on the internal walls of the heat exchange pipework. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 42

· Discharge of up to 450,000m3 per day of cooled seawater at 7oC below ambient seawater o The discharge of cooled seawater could create a denser colder layer on the seabed that may: affect physiological functions of temperature sensitive biota; affect reproductive responses of temperature sensitive species; affect migration or travel paths of temperature sensitive species. · Discharge of up to 450,000m3 per day of seawater containing residual chlorine o The discharge of seawater containing residual chlorine may: be toxic to chlorine sensitive species; affect physiological functions of chlorine sensitive biota; and/or affect reproductive responses of chlorine sensitive species.

The potential impact pathways from the operation of the FSRU on the marine environmental ecosystem have been described and modelled in separate reports, comprising: hydrodynamic and discharge mixing modelling (CEE, 2018a), heat exchange seawater entrainment modelling (CEE, 2018b), the effects of cold-water discharge assessment on the marine ecosystem (CEE, 2018c) and chlorine behaviour investigation and toxicity modelling (CEE, 2018d). The key impact pathways are summarised below.

6.1.1 Entrainment effects and mitigation The operation of the heat exchange system on the FSRU will require a daily volume of up to 450,000 m3 (450 ML/day) of seawater from Western Port to be pumped at a rate of 5.2 m3/s through heat exchangers on-board the FSRU. This is a similar volume of seawater withdrawn by the Victorian Desalination Plant at Wonthaggi (currently at 11.6 m3/s), except that the FSRU will operate continuously for most of the year with downtime for maintenance and variations in flow depending on LNG supply and gas demand.

The heat exchanger intake will be designed to minimise potential effects of seawater entrainment on mobile animals in the water column as shown in Figure 21.

Sea surface - high tide 17 16 15 Sea surface - low tide 14 13 14 m 12 11 4 m 10 9 10 m Intake velocity at grille: 8 Horizontal, 0.1 to 0.15 m/s, Seawater Intake 7 6 Perpendicular to ambient 5 4 5 m 3 2 1 Seabed - fine sand and silt 0

Figure 21. Seawater intake environmental parameters at Crib Point facility

As a result of the design features described above, large and small mobile animals can avoid being drawn into the intake by detecting the intake and swimming away from the screens. This mitigation process has been shown to be very effective in seawater cooling systems and desalination plant systems throughout the world, including the Victorian Desalination Plant at Wonthaggi. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 43

The main unavoidable adverse effect of the heat exchanger system is the potential for entrainment of all the smaller marine organisms (zooplankton and phytoplankton), drifting eggs, larvae and larval fish) in the central part of the water column adjacent to the intake. It is assumed that all of these biota will not survive as a result of mechanical damage and exposure to chlorine biocide (CEE, 2018b).

Estimation of the proportion of planktonic populations that may be entrained are dependent on a range of factors including (1) the nature, distribution and annual variation of planktonic populations in North Arm of Western Port, which are currently undocumented and (2) hydrodynamic model configurations specific to entrainment. It has been recommended that: · Particle entrainment modelling for North Arm be developed to provide entrainment proportion contours · A plankton and larval sampling program be designed and implemented to provide information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. · Available information of literature on the effects of entrainment on semi-enclosed marine ecosystems be reviewed to provide guidance on long-term ecosystem implications of plankton entrainment.

6.1.2 Effects of cold seawater discharge The operation of the heat exchange system on the FSRU will result in the discharge of up to 450,000 m3 per day (450 ML/day) of seawater that is initially 7oC cooler than the surrounding ambient Western Port seawater. The modelling based on a conservative single-port discharge showed that the cold, and therefore dense, seawater leave the single (or double) discharge port of the FSRU and descend towards the seabed where it would form a cool layer during periods of low currents during the turn of the tide (Figure 22). It will mix into the surrounding water column during stronger mid-tidal currents.

Figure 22. Behaviour of cold-water discharge from FSRU at Crib Point

Under this scenario, the maximum temperature difference between ambient seawater and the temperature in the plume after it has undergone the process of ‘initial dilution’ reached the seabed is predicted to be 0.8oC and 0.3oC below ambient for single port and six-port discharges, respectively. The pool of cold-water may extend up to 600 m north during the AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 44 early stage of a rising tide or 600 m south during the early stage of a falling tide and may be up to 250 m wide at the FSRU. The cool pool may be up to 2.5 m thick above the seabed for a single-port discharge, but is less likely to form for a six-port discharge (Figure 23).

0 0 200 400 600 800 1000 Distance from high tide mark, m -5

1 discharge port -10 6 discharge ports

-15 Water depth to LAT, m

-20

Figure 23. Maximum extent of cold water field cross-section (concept)

Seawater temperature above 2.5 m from the seabed will be unaffected by the discharge except for the column of cold-water descending from the depth of the FSRU discharge.

The AGL preferred design for discharge of the cold seawater is through a six-port discharge arrangement, instead of the alternate single (or double) discharge port/s. This optimises dilution of the discharge and results in a smaller temperature difference closer to the discharge point being an area approximately 200 m north and south and 60 m east and west of the discharge point, representing a total seabed area of approximately 5 ha.. No cold- water pool forming on the seabed is likely at any stage of the tide with the six-port discharge.

6.1.3 Chlorine residual in seawater discharge Chlorine will be generated by electrolysis of seawater at the inlet to the seawater exchange system to prevent the settlement and growth of encrusting biota on the interior of the heat exchange pipework (CEE, 2018d). This is standard procedure for heat exchange systems in seawater applications and intakes to desalination plants. The initial concentration of chlorine will be controlled so that the concentration of chlorine at the discharge will be 0.1 mg Cl2/L. The process of initial dilution from the single (or double) discharge port/s will reduce the concentration of free chlorine residual from 0.1 mg Cl2/L at the outlet to 0.01 Cl2/L at the seabed. Reduction of chlorine residual concentration after initial dilution is mixing, time, organic content, salinity and water temperature dependent. After six hours mixing with tidal currents, the chlorine concentration in seawater at ambient temperature of 12oC is estimated o o to reduce to 0.006 Cl2/L, while in warmer seawater (16 C to 18 C) the chlorine concentration o is estimated to reduce to 0.003 mg Cl2/L. A toxicity test at 16 C using Crib Point seawater found that the fertilisation of a local genus of sea urchin was affected after one hour exposure to 0.059 mg Cl2/L.

Agency ecosystem protection guidance values for free chlorine are shown in Table 5.

Table 5. Chlorine ecosystem protection guidance values Agency Protection level Value, mg/L ANZECC 2000 95 % species protection, freshwater and marine* 0.003 USEPA 1985, 1991 Four day mean (chronic), marine 0.0075 USEPA 1985, 1991 One hour mean (acute), marine 0.013 *Value for marine ecosystem “indicative interim working value”. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 45

6.2 Endangered species – preliminary assessment In relation to endangered species (Blue Whales, Southern Right Whales, Leatherback Turtles and Loggerhead Turtles in this case), the EPBC Act Policy Statement 1.1 - Significant Impact Guidelines state that:

An action is likely to have a significant impact on a critically endangered or endangered species if there is a real chance or possibility that it will: · lead to a long-term decrease in the size of a population; · reduce the area of occupancy of the species; · fragment an existing population into two or more populations; · adversely affect habitat critical to the survival of a species; · disrupt the breeding cycle of a population; · modify, destroy, remove, isolate or decrease the availability or quality of habitat to the extent that the species is likely to decline; · result in invasive species that are harmful to a critically endangered or endangered species becoming established in the endangered or critically endangered species’ habitat; · introduce disease that may cause the species to decline; or · interfere with the recovery of the species.

There are no apparent direct or indirect pathways related to the Project that are likely to affect Blue Whales, Southern Right Whales, Leatherback Turtles or Loggerhead Turtles: population size; area of occupancy; population continuity; critical habitat, breeding cycle; or species recovery.

6.3 Vulnerable species – preliminary assessment In relation to vulnerable species (Humpback Whales, White Shark, Australian Grayling and Green Turtles), the EPBC Act Policy Statement 1.1- Significant Impact Guidelines state that:

An action is likely to have a significant impact on a vulnerable species if there is a real chance or possibility that it will: · lead to a long-term decrease in the size of an important population of a species; · reduce the area of occupancy of an important population; · fragment an existing important population into two or more populations; · adversely affect habitat critical to the survival of a species; · disrupt the breeding cycle of an important population; · modify, destroy, remove or isolate or decrease the availability or quality of habitat to the extent that the species is likely to decline; · result in invasive species that are harmful to a vulnerable species becoming established in the vulnerable species’ habitat; · introduce disease that may cause the species to decline; or · interfere substantially with the recovery of the species.

There are no apparent direct or indirect pathways related of the Project that may affect Humpback Whales, White Sharks, or Green Turtles: population size; area of occupancy; population continuity; critical habitat, breeding cycle; or species recovery. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 46

6.3.1 Australian Grayling The potential for effect of the heat exchange system of the Project on Australian Grayling larval dispersion and juvenile migration is assessed on the basis of available information (DELWP Action Statement No 257 DELWP 2015, National Recovery Plan for Australian Grayling Prototroctes maraena, and Victorian Fisheries Authority fish species notes).

Grayling biology The Grayling, although rare, is found in most Victorian coastal rivers and streams from East Gippsland to the Hopkins River in Western Victoria. The National Recovery Plan lists Western Port’s Lang Lang River, Cardinia Creek and Bunyip River among the 35 Victoria, three New South Wales and 30 Tasmanian streams that contain populations important for the long-term survival and of the Grayling. The Victorian Fisheries Authority (vfa.vic.gov.au/education/fish-species/australian-grayling) notes that very large populations of grayling occur in the Mitchell, Tambo and Barwon Rivers.

Adult Grayling live in freshwater rivers and streams and live for two to three years. Mature females produce large quantities of eggs, 25,000 to 68,000 eggs per female. During periods of high flow in April and May, adult males and females migrate downstream to lower reaches where they form spawning aggregations. Eggs are laid in gravel streambeds. The slender and buoyant larvae hatch from the gravel and are swept downstream into estuaries, bays and coastal seas. In the absence of high flows, adults do not migrate downstream, and females reabsorb the eggs they are carrying. Hence, adults may only spawn once in their lives.

The coincidence of spawning and high river flows may assist in broader dispersion of larvae in the nearshore marine environment, where the larvae develop into juveniles and live for six to ten months. The young ‘whitebait’ juvenile grayling migrate back to coastal streams to spend the remainder of their lives in fresh water reaches up to 100 km inland.

Adults appear to remain in the same stream their entire, short lives. Genetic studies of Grayling concluded that there is a single genetic stock along the Victorian coastal distribution. This indicates a high degree of dispersion and mixing during marine stage of the larvae and juveniles along the entire coast. This is further indicated in the National Recovery Plan conclusion that the species appears to be “able to recolonise rivers from which it has been excluded…for decades.”

Assessment of effect The Project processes that may affect Grayling are related to 1. Potential entrainment of: a. larvae during dispersion from freshwater streams into the marine environment, and b. juveniles that may live in or migrate through Western Port during their six to ten month marine phase. 2. Potential effects of the cold water discharge on dispersing larvae and migrating juveniles. 3. Potential toxic effects of free chlorine in the cold water discharge on dispersing larvae and migrating juveniles.

Larvae Larvae may disperse into the marine environment during high freshwater flows from the Cardinia Creek, Bunyip River and Lang Lang River in the Embayment Head of Upper North Arm. The larvae are buoyant and will be located in the surface freshwater layer of the northern part of the Bay during wet weather events. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 47

Figure 24. Location of grayling waterways in Upper North Arm AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 48

Figure 25. General water movement in Western Port

General water movement in Western Port (Figure 25) shows a clockwise pattern of movement, with net current in the embayment head in the region of the rivers containing Grayling populations towards the east and then down the Corinella Segment. Hence a high proportion of larvae are likely to follow the currents down the eastern side of French island not past Crib Point.

Any proportion of larvae that may drift past Crib Point are likely to be in the surface layer as they are buoyant, and are therefore unlikely to be entrained by the intake located at least 4 m below the surface or be exposed to cold water or chlorine that are located within 2.5 m of the seabed.

Juveniles Juvenile Grayling that live in the marine environment and migrate to suitable river systems are independent swimmers and are likely to avoid the intake current.

Adults Based on the extent of potential impact pathways and the distribution of adult Grayling, the Project will have negligible effect on adult Grayling populations in freshwater reaches of Victorian streams.

6.4 Migratory species – preliminary assessment In relation to migratory species that are not listed as threatened species (Bryde’s Whale, Pygmy Right whale, Dusky Dolphin, Killer Whale and Mackerel Shark), the EPBC Act Policy Statement 1.1- Significant Impact Guidelines state that:

An action is likely to have a significant impact on a migratory species if there is a real chance or possibility that it will: · substantially modify (including by fragmenting, altering regimes, altering nutrient cycles or altering hydrological cycles), destroy or isolate an area of important habitat for a migratory species; AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 49

· result in an invasive species that is harmful to the migratory species becoming established in an area of important habitat for the migratory species; or · seriously disrupt the lifecycle (breeding, feeding, migration or resting behaviour) of an ecologically significant proportion of the population of a migratory species.

Based on the EPBC Act Policy Statement 1.1- Significant Impact Guidelines and the potential impact pathways described for the AGL Gas Import Jetty Project, there are no apparent direct or indirect pathways related of the Project that may affect Bryde’s Whale, Pygmy Right whale, Dusky Dolphin, Killer Whale and Mackerel Shark: population size; area of occupancy; population continuity; critical habitat, breeding cycle; or species recovery.

6.5 Preliminary assessment of FFG marine listed species and communities Most of the marine species and communities listed under the FFG Act are relatively remote from Crib Point and the possible risk to those species and communities from development and operation of the natural gas facility at Crib Point is negligible. Project risk screening will finalise the risk level for these species based on the above review information and project specific potential impact pathways.

6.5.1 Pale mangrove goby or flatback mangrove goby The pale mangrove goby Mugilogobius paludis is listed as under the FFG Act as threatened and was recorded near Crib Point. However, as discussed in Section 5.4.5, this species is actually the flatback mangrove goby M platynotus, which is not listed as threatened under the FFG Act. The flatback mangrove goby is found only along the coast of eastern Australia and Western Port is the southeastern limit of its distribution.

The pale mangrove goby lives mostly in burrows among mangrove roots in the upper intertidal zone. Goby species vary considerably in their reproductive characteristics. Eggs may remain close to the position they are laid and fertilized, where they may be protected by the male. Hatched larvae, however, disperse from the mangrove habitats and have multiple stages that drift with ambient currents for weeks or months before they return to occupy suitable habitat as adults.

The location and positioning of the intake in the mid-water column will minimize entrainment of larvae if they have a preference for dispersal along natural boundaries. Further clarification of the status of this species on the FFG threatened species list is required.

6.5.2 Ghost shrimps Two species of ghost shrimp are known from collections near Crib Point more than 50 years ago: the Western Port ghost shrimp Pseudocalliax tooradin and the small-gilled ghost shrimp Michelea microphylla. The location of the collections in Western Port are shown in Figure 26. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 50

Figure 26. Locations of collection of FFG listed ghost shrimps near Crib Point

The local significance of both species is noted in the Western Port Ramsar Site Management Plan 2017.

Four individuals of Pseudocalliax tooradin were collected in grab sampling at 5 m depth (with one specimen collected from an unknown depth) during a survey in 1965. One other specimen of this species was collected at 2 m depth in Swan Bay in Port Phillip in 1982. Hence, this species is reasonably documented as a rare species.

One individual of Michelea microphylla, the only individual of this species known to exist, was found at 19 m depth. Dr Gary Poore, Emeritus Curator at the Museum of Victoria and the taxonomist who scientifically described this crustacean as a species, advised that the specimen he examined was complete, had features that were notably distinct from other ghost shrimp species and was definitely a separate and rare species. Dr Poore explained that, like Pseudocalliax and other ghost shrimps, this shrimp is a burrowing species and may occupy a deep burrow. This specimen was found in relatively deep water in sediments that is not often sampled to the depth of sediment occupied by the animal and its general location in Western Port. In conclusion, even though no specimens have been identified in more than 50 years, Dr Poore considered that it is still likely to be present in low numbers in suitable habitat.

Victorian Regional Channels Authority (VRCA) is responsible for maintaining navigational water depths into Geelong, Western Port and Portland. VRCA intend to level 95 m2 of isolated high points at Berth 2 of Crib Point Jetty and engaged CEE to investigate the presence of threatened ghost shrimps in the vicinity of the high points (CEE 2018e). The investigation was designed by experienced marine biologists from CEE in consultation with Dr J Watson (Marine Science and Ecology) and Dr G Poore from the Museums of Victoria. The area was surveyed on 13 July 2018. No threatened species of ghost shrimp were found during the survey. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 51

6.5.2.1 Assessment of entrainment effect Both of these shrimps may have planktonic larvae with planktonic durations that could result in their susceptibility to entrainment. For example, some species of ghost shrimps in Western Port to related to Pseudocalliax tooradin and Michelea microphylla have larval periods (with four or five stages) totalling more than 15 days, while others have larval periods (with only two or three planktonic stages) totalling less than 14 days, while other have been estimated at six weeks (Butler, Reid and Bird, 2009). The behaviour of larvae in the water column is not known.

The adults of Pseudocalliax tooradin and Michelea microphylla have distributions that are restricted to the proximity of Crib Point. Preliminary modelling of biological entrainment by CEE for this Project (CEE, 2018b) shows that up to 10 per cent of larvae released on the western edge of the channel (including the adjacent mudflats) within about 750 m of Crib Point may be entrained into the heat exchange system of the FSRU. These levels may represent a significant proportion for these rare species if they are present within the Crib Point region.

6.5.2.2 Assessment of cold water and chlorine toxicity effect Pseudocalliax tooradin was found at 5 m depth in Western Port and 2 m depth in Swan Bay. This would indicate that the species may be restricted to depths shallower than the cold water plume. Hence it may not be affected by temperature or chlorine toxicity effects. However, its distribution is only known from two samples. Hence, it may occur sparsely over a greater depth range.

Michelea microphylla was found approximately 2.4 km north of Crib Point Jetty, in gravelly seabed, at 19 m depth in the main North Arm channel. Its proximity to the FSRU, its presence close to the footprint of the cold-water pool and its occupancy of burrows indicates that it is susceptible to the cold-water discharge and residual chlorine toxicity exposure.

The impact of the discharge in seabed biota may be mitigated by discharge through a multi- port discharge that would increase dilution of the discharge and reduce the extent of possible toxicity effects.

6.5.2.3 Combined effect and recommendation The combined effect of the cold-water discharge (including residual chlorine) and entrainment may be sufficient to affect populations of benthic species in the near proximity of the discharge. However, the distribution of benthic invertebrates including ghost shrimps in the channels of Western Port, including North Arm, has not been documented for more than 50 years. Hence, it is recommended that targeted sampling for these particular threatened ghost shrimps (as well as infauna and epifauna in general) be designed and implemented to document the present status of threatened species and character of the benthic invertebrate community. The study would also guide further assessment of the effects of the proposal on the marine ecosystem habitat of the channel soft sediment seabed.

6.6 Ramsar area The designation of a Ramsar area is primarily based on its international importance to waterbirds. The marine environmental impact pathways described in Section 6.1 are highly unlikely to directly affect the activities of waterbirds in the intertidal areas and roosting areas of the Western Port Ramsar area.

As discussed in Section 4, Western Port meets seven of the nine criteria, but may meet eight of the criteria if Criterion 9 (below) includes FFG threatened species discussed in Section 5. The potential effects of impact pathways described in Section 6.1 on the Ramsar selection Criteria relevant to Western Port are summarised in Table 6. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 52

Table 6. Assessment of Ramsar Selection Criteria

Ramsar criteria (based on DEE Criteria) Potential effect

Criterion 1: Representative, rare, or Project does not involve physical changes unique example of a natural or near- to Western Port beyond jetty berths natural wetland type. Criterion 2: Supports vulnerable, Possible localised effects on some state endangered, or critically endangered listed threatened marine invertebrate species or threatened ecological species in North Arm communities. Criterion 3: Supports populations of plant Negligible effect on seagrasses and and/or animal species important for mangroves. Potential localised effects on maintaining the biological diversity. channel soft seabed communities Criterion 4: Supports plant and/or animal Possible effects on plankton and species at a critical stage in their life planktonic life stages of some marine cycles, or provides refuge during adverse invertebrate species conditions. Criterion 5: Regularly supports 20,000 or Marine pathways are unlikely to directly more waterbirds. affect waterbirds in North Arm and most unlikely to affect waterbirds elsewhere in Western Port Criterion 6: Regularly supports 1% of the Marine pathways are most unlikely to individuals in a population of one species directly affect waterbirds or subspecies of waterbird. Criterion 7: Supports a significant N/A proportion of indigenous fish subspecies, species or families, life-history stages, species interactions and/or populations that are representative of wetland benefits and/or values and contributes to global biological diversity. Criterion 8: Important source of food for Possible effects on plankton and fishes, spawning ground, nursery and/or planktonic life stages of some marine migration path on which fish stocks, either invertebrate species within the wetland or elsewhere, depend. Criterion 9. Regularly supports 1% of the Possible effect on small-gilled ghost individuals in a population of one species shrimp population or subspecies of wetland-dependent non- avian animal species.

The table indicates that there is negligible to low risk to five of the Ramsar criteria. There is negligible risk to those criteria directly involving waterbird populations. There is possible interaction of the Project (cold-water discharge and entrainment pathways) with aspects of four Ramsar Criteria. This interaction is expected to occur within a confined part of North Arm within the larger Western Port Ramsar area and is unlikely to affect waterbird populations.

The level of potential effect on marine ecosystem values in the vicinity of the proposal within North Arm has been discussed in more detail in the plume dispersion report and modelling and assessment of biological entrainment reports. Benthic habitats in water depths less than less than 12.5 m will be unaffected by the direct effects of FSRU operation. These unaffected AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 53 habitats include intertidal saltmarsh, mangroves, seagrass and mudflat habitats, which are valuable foraging and roosting habitats for waterbirds. Subtidal seagrass and shallow, bare seabed habitats will also be unaffected by direct effects.

CEE marine ecosystem assessment reports (including this one) have recommended mitigation measures to minimise potential effects on the marine ecosystem including intake design for heat exchange system and multi-port discharge arrangement.

The general outcome of the reports indicates that the direct effects of the full-scale operation of the FSRU on the marine ecosystem in the Ramsar area will relate to discharge of cold- water, discharge of residual chlorine and entrainment of larvae and plankton. As stated above, the extent of cold-water and chlorine toxicity effects are likely to be restricted to an area approximately 200 m north and south and 60 m east and west of the discharge point in water depth from approximately 12.5 m to 17 m. This represents an area of approximately 5 ha, which is less than 0.5 % of the seabed depth in North Arm. Entrainment of up to 10 percent may extend to 750 m north and south from the FSRU, but overall entrainment in North Arm is expected to be less than 1 % of the whole of the North Arm.

The predominant habitats in the area are: bare soft seabed habitats occupied by invertebrate communities (infauna and epibiota) and some mobile fish, and; planktonic communities in the constantly moving water column of the main North Arm channel.

The longer term effects of entrainment on planktonic populations (including some planktonic larvae and eggs) are uncertain due to the possible intermittent and variable operation of the FSRU which depends on uncertain national and state energy supply options and state energy demands in the near future and over the next decades.

The modelling completed for this report and other supporting studies was based on the original FSRU seawater flow-through rate of 450,000 m3/day (450 ML/day). AGL has advised that a seawater flow-through rate of 300,000 m3/day (300 ML/day), corresponding to a lower regasification rate is more likely. In this case, the proportion of plankton entrained may be reduced by approximately one third.

CEE marine ecosystem assessment reports (including this one) have recommended further studies to inform assessment of the nature and extent of potential effects on the North Arm Ramsar marine ecosystem. The recommended studies from the marine ecosystem reports are: · Benthic invertebrate sampling to document the present characteristics and distribution of epibiota and infauna including targeted investigation to evaluate the existence of ghost shrimp species; · Measurement of short-term and long-term water temperature variations to provide natural variation context for assessment of cold-water discharge differentials · Refinement of North Arm hydrodynamic models to assist refinement of discharge dispersion models and entrainment estimation models · Development of entrainment models for North Arm to provide plankton entrainment proportion contours · A plankton and larval sampling program to provide information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. · Review of available literature on the effects of entrainment on semi-enclosed marine ecosystems to provide guidance on long-term ecosystem implications of plankton entrainment. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 54

7 CONCLUSION The review of marine Commonwealth EPBC Act matters of national environmental significance and the State FFG Act listed species has been completed for the AGL Gas Import Jetty Project. The assessment identified 33 threatened marine species (excluding birds) and one marine community that the Acts list may occur in Western Port.

CEE’s review found that many of the species in the State and Commonwealth Acts were relatively widely distributed, that Western Port represented a small component of their range and that Western Port was not recognised as a significant aggregation, breeding or feeding location or migratory path for most EPBC identified species and many FFG listed species (excluding water birds).

The initial review identified four species where further investigations have been undertaken to inform this assessment: · Australian Grayling Prototroctes maraena: EPBC Act ‘Vulnerable’; FFG listed · Pale Mangrove Goby Mugilogobius paludis: FFG listed · Western Port ghost shrimp Pseudocalliax tooradin: FFG listed · Ghost shrimp Michelea microphylla: FFG listed

Further examination of information about the Australian Grayling indicated that adult populations in the rivers and streams would not be exposed to impact pathways and that the proportion of larvae of these species that might disperse via North Arm and be affected by Project processes was low.

Museums of Victoria personnel advised that the Pale Mangrove goby Mugilogobius paludis was synonymous with the more common flatback goby Mugilogobius platynotus, which is not listed on the FFFG threatened species list.

The Western Port ghost shrimp Pseudocalliax tooradin and the ghost shrimp Michelea microphylla are known from collections near Crib Point more than 50 years ago. The Western Port ghost shrimp Pseudocalliax tooradin is known from a total of five records, and the ghost shrimp Michelea microphylla is known from only one specimen. No further records of the ghost shrimp species have been recorded since 1965 in Western Port or elsewhere (with the exception of Western Port ghost shrimp with one additional record outside of Western Port in 1982). This is despite a comprehensive sampling program for the Western Port study in the 1970s (Coleman et al, 1978).

Benthic habitats in water depths less than less than 12.5 m of the Ramsar area will be unaffected by the direct effects of the seawater heat exchange discharge from the FSRU operation. These unaffected habitats include intertidal saltmarsh, mangroves, seagrass and mudflat habitats, which are valuable foraging and roosting habitats for waterbirds. Subtidal seagrass and shallow, bare seabed habitats in the Ramsar area will also be unaffected by direct effects.

CEE marine ecosystem assessment reports (including this one) have recommended mitigation measures to minimise potential effects on the marine ecosystem including intake design for heat exchange system to minimise entrainment of biota from the water column and multi-port discharge arrangement to minimise effects of cold-water discharge on marine biota.

The general outcome of the reports indicates that the direct effects of the full-scale operation of the FSRU on the marine ecosystem in the Ramsar area relate to discharge of cold-water, discharge of residual chlorine and entrainment of larvae and plankton. As stated above, the AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 55 extent of cold-water and chlorine toxicity effects are likely to be restricted to an area approximately 200 m north and south and 60 m east and west of the discharge point in water depth from approximately 12.5 m to 17 m. This represents an area of approximately 5 ha, which is less than 0.5 % of the seabed in North Arm2. Entrainment of up to 10 percent of some plankton and larvae may extend to 750 m north and south from the FSRU, but overall entrainment in North Arm is expected to be less than 1% of the whole of the North Arm. The predominant habitats in the area that may be affected are: bare soft seabed habitats occupied by invertebrate communities (infauna and epibiota) and some mobile fish, and; planktonic communities in the constantly moving water column of the main North Arm channel.

The longer term effects of entrainment on planktonic populations (including some planktonic larvae and eggs) are uncertain due to the possible intermittent and variable operation of the FSRU which depends on uncertain national and state energy supply options and state energy demands in the near future and over the next decades. The duration of operation will depend in multiple factors including security of energy supply and raw energy supply markets.

AGL is committed to further marine environmental studies prior to operation and is presently considering: · Benthic invertebrate sampling to document the present characteristics and distribution of epibiota and infauna including targeted investigation to evaluate the existence of ghost shrimp species; · Measurement of short-term and long-term water temperature variations to provide natural variation context for assessment of cold-water discharge differentials · Refinement of North Arm hydrodynamic models to assist refinement of discharge dispersion models and entrainment estimation models · Development of entrainment models for North Arm to provide plankton entrainment proportion contours · A plankton and larval sampling program to provide information on spatial and temporal variations in plankton populations in North Arm focussing on the proposed location and position of the FSRU intake. · Review of available literature on the effects of entrainment on semi-enclosed marine ecosystems to provide guidance on long-term ecosystem implications of plankton entrainment.

These studies will inform a works approval application under the Environment Protection Act 1970 and in accordance with the relevant associated regulations, including the State Environment Protection Policy (Waters of Victoria).

2 Percentage based on the area of North Arm which is greater than 10 m depth. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 56

8 REFERENCES Atlas of Living Australia (2017), CSIRO and NCRIS. https://www.ala.org.au/ accessed September 2017. Australian Wetlands Database (2017) Ramsar Wetlands: Western Port. http://www.environment.gov.au/cgi-bin/wetlands/ramsardetails.pl?refcode=19 accessed September 2017 Bok, M, Chidgey, S., Crockett, P. (2017) Five years on: monitoring of Long Island Point’s Western Port wastewater discharge. The APPEA Journal 57:10-25. CEE 2009. Port of Hastings Stage 1 Development. Marine Ecosystem Preliminary Considerations. Report to AECOM and Port of Hastings Corporation. CEE, Melbourne, August 2009. CEE 2014. Port of Hastings Seagrass Monitoring Pilot Study. Report to Port of Hastings Development Authority. CEE Melbourne June 2014. CEE (2016). Long Island Point Wastewater discharge. Marine Ecological and water quality monitoring 2010 – 2016. CEE report to Esso Australia CEE (2018a) Plume Modelling of Discharge from LNG Facility at Crib Point, Western Port – AGL Gas Import Jetty Project. Report for AGL. Report for AGL. CEE (2018b) Modelling and Assessment of Biological Entrainment – AGL Gas Import Jetty Project. Report for AGL. CEE (2018c) Assessment of effects of cold-water discharge on marine ecosystem at Crib Point – AGL Gas Import Jetty Project. Report for AGL. CEE (2018d) Chlorine in FSRU Seawater Processes – AGL Gas Import Jetty Project. Report for AGL. CEE (2018e) Threatened ghost shrimp survey Berth 2 Crib Point Jetty Risk from bed levelling of isolated high points. Report to VRCA, August 2018. Cohen, B.F., McArthur, M.A. & Parry, G.D. (2000) Exotic marine pests in Westernport. Report No. 22. Marine and Freshwater Resources Institute, Queenscliff, Vic. Cohen, B.F., McArthur, M.A. & Parry, G.D. (2001) Exotic marine pests in the Port of Melbourne, Victoria. Report No. 25. Marine and Freshwater Resources Institute, Queenscliff, Vic. Coleman N, W Cuff, M Drummond and JD Kudenov (1978). A quantitative survey of the macrobenthos of Western Port, Victoria. Australian Journal of Marine and Freshwater Research 29(4):445 - 466 Crook, D.A., J. I. Macdonald, J.P. O’Connor, B. Barry (2006) Use of otolith chemistry to examine patterns of diadromy in the threatened Australian grayling Prototroctes maraena. Journal of Fish Biology. Currie, D.R. & Crookes, D.P. (1997) Exotic marine pests in the Port of Hastings, Victoria. Report No. 4. Marine and Freshwater Resources Institute, Queenscliff, Vic. Currie, D.R., McArthur, M.A. & Cohen, B.F. (1998) Exotic marine pests in the Port of Geelong, Victoria. Report No. 8. Marine and Freshwater Resources Institute, Queenscliff, Vic. DA/DE (2015) Antifouling and In-Water Cleaning Guidelines, April 2015. Australian Government Department of Agriculture | Department of the Environment. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 57

DAWR (2015) Review of national marine pest biosecurity. Australian Government Department of Agriculture and Water Resources, Canberra. DAWR (2018) Managing biofouling in Australia. Australian Government Department of Agriculture and Water Resources, Canberra. http://www.agriculture.gov.au/biosecurity/avm/vessels/biofouling. Viewed: 22 February 2018. DoEE (2014) Recovery Plan for the Grey Nurse Shark (Carcharias taurus), Department of Environment and Energy, Canberra. DELWP (2016) Benefits of environmental water – Spawning of Australian Grayling in four coastal rivers. Fact Sheet 3 – Spawning success of Australian Grayling. DELWP (2017). Western Port Ramsar Site Management Plan Summary. Department of Environment, Land, Water and Planning, East Melbourne. DEPI (2013) Action Statement Three Year Plan: A three year implementation plan for Action Statements. Victorian Government Department of Environment and Primary Industries, East Melbourne. DSE (2003) Action Statement No. 115: Australian Mudfish Neochanna cleaveri. Victorian Government Department of Sustainability and Environment, East Melbourne. DELWP (2015) Action Statement No. 257: Australian Grayling Prototroctes maraena. Victorian Government Department of Environment, Land Water and Planning, East Melbourne. DELWP (2015) Action Statement No. 259: Australian Whitebait Lovettia sealii. Victorian Government Department of Environment, Land Water and Planning, East Melbourne. DELWP (2017). Western Port Ramsar Site Management Plan Summary. Department of Environment, Land, Water and Planning, East Melbourne. DEWHA (2009) Threat abatement plan for the impacts of marine debris on vertebrate marine life. Australian Government Department of the Environment, Water, Heritage and the Arts, Canberra. DSE (2003) Action Statement No. 18: San Remo Marine Community. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2004) Action Statement No. 94: Southern Right Whale Eubalaena australis. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2004) Action Statement No. 100: Introduction of exotic organisms into Victorian marine waters. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2003) Action Statement No. 185: Great White Shark Carcharodon carcharias. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2003) Action Statement No. 186: Grey Nurse Shark Carcharias taurus. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2003) Action Statement No. 197: Southern Bluefin Tuna Thunnus maccoyii. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2009) Action Statement No. 242: Blue Whale Balaenoptera musculus. Victorian Government Department of Sustainability and Environment, East Melbourne. DSE (2009) Action Statement No. 247: Humpback Whale Megaptera novaeangliae. Victorian Government Department of Sustainability and Environment, East Melbourne. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 58

DSE (2009) Action Statement No. 250: Leathery Turtle Dermochelys coriacea. Victorian Government Department of Sustainability and Environment, East Melbourne. EPA (1996) The Western Port Marine Environment. EPA Publication no 493. Environment Protection Authority EPA (2001) Protecting the Waters of Western Port and Catchment. EPA Publication no 797. Environment Protection Authority Hewitt, C. & Martin, R. (1996) Port surveys for introduced marine species – background considerations and sampling protocols. Technical Report No. 4. Centre for Research on Introduced Marine Pests, CSIRO Marine Research, Hobart, Tas. Hewitt, C.L., Campbell, M.L., Thresher, R.E. & Martin, R.B. (eds) (1999). Marine biological invasions of Port Phillip Bay, Victoria. Technical Report No. 20. Centre for Research on Introduced Marine Pests, CSIRO Marine Research, Hobart, Tas. Hewitt, C.L., Campbell, M.L., Thresher, R.E. & Martin, R.B. (eds) (1999). Marine biological invasions of Port Phillip Bay, Victoria. Technical Report No. 20. Centre for Research on Introduced Marine Pests, CSIRO Marine Research, Hobart, Tas. Hewitt, C. & Campbell, M. (2008) Assessment of relative contributions of vectors to the introduction and translocation of marine invasive species. Final Report for Project 9/2007. An independent report undertaken for the National System for the Prevention and Management of Marine Pest Incursions, Department of Agriculture, Fisheries and Forestry, Canberra Hindell and Jenkins (2003). Spatial and temporal variability in the assemblage structure of fishes associated with mangroves (Avicennia marina) and intertidal mudflats in temperate Australian embayments. Marine Biology 144:385-395. Hirst, A., Bott, N., Lee, R. (2013). Plankton survey of Asterias amurensis larvae in coastal waters of Victoria (August-September 2012) – Final Report. Fisheries Technical Report 178, Department of Primary Industries, Queenscliff, Victoria, Australia. Jacobs (2018a). Flora and Fauna Assessment – AGL Gas Import Jetty Project. Report for AGL. Jacobs (2018b). Greenhouse Gas Emissions Assessment – AGL Gas Import Jetty Project. Report for AGL. Jacobs (2018c). Crib Point Jetty Upgrade Environmental Risk Assessment. Report for Port of Hastings Development Authority. Jenkins (2015). Spatial and temporal variability in the assemblage structure of fishes associated with mangroves (Avicennia marina) and intertidal mudflats in temperate Australian embayments. Marine Biology 144:385-395. KBR (2010) (Kellogg Brown & Root), Western Port Ramsar Wetland Ecological Character Description. Report for Department of Sustainability, Environment, Water, Population and Communities, Canberra. Kimmerer W and A D McKinnon (1987a) Zooplankton in a marine bay.I. Horizontal distributions to estimate net population growth rates. Mar Ecol Prog Ser 41: 43- 52. Kimmerer W and A D McKinnon (1987b) Zooplankton in a marine bay.II. Vertical migration to maintain horizontal distributions. Mar Ecol Prog Ser 41: 53-60. Last and Stevens (2005). Sharks and Rays of Australia. Publisher CSIRO Collingwood, VIC. AGL Gas Import Jetty Project – Marine Ecosystem Protected Matters Assessment 59

O’Hara, T. and Barmby, V. (2000). Victorian Marine Species of Conservation Concern: Molluscs, Echinoderms and Decapod Crustaceans. Parks, Flora and Fauna Division, Department of Natural Resources and Environment, East Melbourne, Australia. Marine Science and Ecology (1990) History and Review of Marine Environmental Monitoring in Western Port, 1972-1989. Prepared for BHP International Steel Coated Products by Marine Science and Ecology, Environmental Consultants. Marine Science and Ecology (2009) History of Marine Ecological Monitoring for Cold Strip Mill, 1973-2009, North Arm Channel, Western Port, Victoria, Report to CEE, June 2009. Melbourne Water (2011) Understanding the Western Port Environment, A summary of current knowledge and priorities for future research. Editors M J Keough and R Bathgate for Melbourne Water, Port Phillip and Westernport CMA, Victoria. November 2011. Ministry for Conservation (1975) Westernport Bay Environmental Study 1973-1974. Ministry for Conservation, Victoria.NIMPIS (2009) National Biofouling Management Guidelines for Commercial Vessels. The National System for the Prevention and Management of Marine Pest Incursions, Australian Government, Canberra. PoHDA (2017) Port Operating Handbook. Port of Hastings Development Authority, Hastings, Victoria Poore G C B (2004) Marine decapod crustacea of Southern Australia: A guide to identification. Museum of Victoria. CSIRO Publishing. Ross, G.J. (2006) Review of the Conservation Status of Australia’s Smaller Whales and Dolphins, report to the Australian Government Department of Environment. http://www.environment.gov.au/system/files/pages/e94eb941-2ff5-4a29-89a3- 891059be4e47/files/co02conservation-smaller-whales-dolphins.pdf Threatened Species Scientific Committee (2001) Commonwealth Listing Advice on Loss of terrestrial climatic habitat caused by anthropogenic emissions of greenhouse gases. http://www.environment.gov.au/cgi-bin/sprat/public/publicshowkeythreat.pl?id=7 Watson, J. (2015) Ralpharia coccinea Hydroid in Museums Victoria Collections https://collections.museumvictoria.com.au/species/14033 Accessed September 2017 Warneke (1995) Australian fur seal Arctocephalus pusillus (Schreber, 1775). Pp. 680-682 in The mammals of Australia ed by R. Strahan. Reed Books: Chatswood. Whitley (1930) Ichthyological miscellanea. Memoirs of the Queensland Museum 10:9-31

Attachment 10

Report to: Jacobs Group (Australia) Pty Ltd

AGL Gas Import Jetty Project Crib Point Jetty, Western Port

Effects of LNG Facility on Sea Level and Seabed at Crib Point Jetty

FINAL

30 August 2018 Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at Crib Point Jetty

Effects of LNG Facility on Sea Level and Seabed at Crib Point Jetty

Contents

1. Project overview ...... 1 2. Purpose of this report ...... 1 3. Background ...... 2 4. Change in Cross-sectional Area ...... 3 5. Calculate Backwater Head Loss Using Bridge Pier Formula ...... 4 6. Head Loss Using Energy Balance Formula ...... 5 7. Reduction in Water Level over Tide Cycle ...... 6 8. Assessment of Results ...... 6 9. Local Erosion ...... 7 10. Conclusion ...... 7 11. References ...... 8 Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at Crib Point Jetty

Report to Report prepared by Ian Wallis CEE Pty Ltd Unit 4, 150 Chesterville Rd Cheltenham, VIC, 3192 Ph. 03 9553 4787

Document History

Document Details Job Name AGL Gas Import Jetty Project Job No. IS210700 Effects of LNG Facility on Sea Level and Seabed at Crib Point Document Jetty

Revision History Revision Date Prepared Checked Approved by By By Final (Ver 01) 19/07/18 Name I Wallis S Chidgey S Ada Final (Ver 02) 30/08/18 Name I Wallis S Chidgey S Ada

This report constitutes the professional opinion and judgement of Consulting Environmental Engineers Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 1 Crib Point Jetty

Effects of Shipping Associated with LNG Facility

1. Project overview AGL Wholesale Gas Limited (AGL) is proposing to develop a Liquefied Natural Gas (LNG) import facility, utilising a Floating Storage and Regasification Unit (FSRU) to be located at Crib Point on Victoria’s Mornington Peninsula. The project, known as the “AGL Gas Import Jetty Project” (the Project), comprises: · The continuous mooring of the FSRU at the existing Crib Point Jetty, which will receive LNG carriers of approximately 300m in length · The construction of ancillary topside jetty infrastructure (Jetty Infrastructure), including high pressure gas unloading arms and a high-pressure gas flowline mounted to the jetty and connecting to a flange on the landside component to allow connection to the Crib Point Pakenham Pipeline Project.

The FSRU will be continuously moored to receive LNG cargos from visiting LNG carriers, store the LNG and re-gasify it as required to meet demand for high pressure pipeline gas.

2. Purpose of this report The scope of this assessment was to investigate the presence of the FSRU and LNG carrier in terms of the potential restriction to the flow of seawater in the western channel and, if so, what are the likely changes in water level in the upper part of Western Port. The potential for local erosion impacts associated with the shipping operations is also considered. This report was prepared in support of: · A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), and · A referral under the Victorian Environment Effects Act 1978.

Figure 1. Proposed Berthing Arrangement for Vessels at Crib Point (north is to left of figure) Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 2 Crib Point Jetty

3. Background The FSRU and LNG carriers are both large vessels and will be frequently moored side by side at the Crib Point Jetty on the western side of the western channel of Western Port. Figure 1 shows the proposed berthing arrangement (north is to the left side of Figure 1).

Table 1 lists the principal dimensions of the likely vessels at Crib Point. Moored together, the two vessels will occupy a width of 90 m and a depth of 12.5 to 12.6 m. An obvious question is whether this large volume creates a significant restriction to the flow of seawater in the western channel and, if so, what are the likely changes in water level in the upper part of Western Port.

Table 1. Likely Dimensions of FSRU and LNG Carrier Vessels FSRU LNG LNG Moss Membrane Carrier Carrier Displacement, MD (T) 132,855 121,990 118,900 Deadweight Tonnage, DWT(T) 95,106 89,557 84,878 Net Tonnage 36,793 31,102 36,480 Overall length, LOA (m) 295 295 288 Length between perpendiculars, Lpp (m) 284 284 274 Beam (m) 46.4 43.4 49.0 Moulded Depth (m) 26.5 26.0 26.8 Laden Tropical Draft (m) 12.6 12.5 12.33 Wharfside operating draft (m) TBA TBA TBA Ballast Draft (m) 9.4 9.5

To answer this question, the following analysis has been made: · Calculate change of cross-sectional area of west channel; · Calculate backwater and head loss using bridge pier formula; · Check head loss using energy balance formula; · Predict reduction in water level over tide cycle; and · Compare to natural variations in average sea level and sea level rise. Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 3 Crib Point Jetty

4. Change in Cross-sectional Area The first step is to determine the proportion of the channel area that would be occupied by the two vessels. Figure 2 shows the section taken across the west channel and the depth profile on this section.

Figure 2. Cross Section through West Channel of WPB

By integration of depths across the section, it was calculated that the cross-sectional area of the western channel at MSL is 47,300 m2. From the vessel dimensions in Table A1 the submerged cross-sectional area of the two vessels is 1,000 m2. Thus the two vessels represent an approximate 2.1 per cent reduction in the cross-sectional area of the channel. This reduction in cross-section has occurred in the past - Crib Point has been used as a port for many years and double-berthing occurs at this jetty. Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 4 Crib Point Jetty

5. Calculate Backwater Head Loss Using Bridge Pier Formula There are several methods that can be used to calculate the head loss due to the constriction caused by the vessels. One established method is to assume the vessels are similar to a streamlined bridge pier, and use the results of studies of head loss at bridges as a basis for calculation.

The head loss formula is based on an extensive series of measurements as described by Charbeneau and Holley (2001). Their experiments considered a reduction of channel area from 2.5 per cent (close to the Crib Point situation) to 15 per cent, and for flow Froude Numbers of 0.1 to 0.9 (somewhat higher than the condition at Crib Point because of the large depth of flow at the berth).

They compared six methods to calculate the head loss and found all give similar results. Their preferred formula is:

where Δy is the reduction in depth, y is the head (or water level) upstream of the vessel, β and µ are constants derived from the experiments, K is effectively a drag coefficient (and equal to 0.9 for a ship-shaped bridge pier), α is the proportional reduction in cross section and equals 0.979 in this case and F is the Froude Number of the flow (calculated from the tidal velocity V and the water depth y).

The tidal velocities at the Crib Point berth are taken from measurements summarised by RJH-DNV (2015) in a report to the Port of Hastings and are summarised in Table 2. Flood current speeds range from 0.05 to 0.55 m/s.

Table 2. Tidal Velocities at Crib Point (from RH-DNV)

Charbeneau and Holley present the results for head loss in terms of non-dimensional flow and depth parameters. The head loss increases as a function of Froude Number (or current Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 5 Crib Point Jetty

speed). For the convenience of the reader, the results have been converted to a dimensional plot showing the reduction in depth (Δy in mm) as a function of the tidal velocity (V in m/s).

1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Head loss, mm 0.2 0.1 0.0 0 0.1 0.2 0.3 0.4 0.5 0.6 Current speed, m/s

Energy Loss Bridge Pier

Figure 3. Head Loss at Crib Point in West Channel of WPB

The green curve in Figure 3 shows the reduction in water level as a function of the flood tide speed, based on the bridge pier results. It can be seen that even at the peak current speed of 0.55 m/s, the change in upstream water level is less than 0.5 mm. Integrating over the full flood tidal cycle, the reduction in upstream water level would be smaller, as explained below.

6. Head Loss Using Energy Balance Formula As a check, the head loss has been calculated by a different method, which determined the energy lost from the flow due to the form drag of the two vessels (Pun and Law, 2015). Essentially this method is equivalent to adding the constriction and expansion losses, and can be expressed as:

2 2 Δy = Cd (Va – Vb ) / 2g where Δy is the reduction in depth, Cd is the overall drag coefficient, Va is the upstream velocity, Vb is the velocity at the constriction and g is gravity.

The pink curve in Figure 3 shows the reduction in water level as a function of the flood tide speed, based on the energy balance approach. It can be seen that even at the peak current speed of 0.55 m/s, the change in upstream water level is about 0.7 mm. Integrating over the full flood tidal cycle, the reduction in upstream water level would be smaller, as explained below. Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 6 Crib Point Jetty

7. Reduction in Water Level over Tide Cycle The seawater entering the upper part of Western Port through the flood tide cycle travels at a range of speeds through the tide cycle, as indicated in Table A2. Thus the overall (or tidally-averaged) reduction in water level obtained by integrating flow and head loss over the cycle. This process results in the estimated loss of upstream water level, as follows: · For bridge per formula, water level is 0.24 mm · For energy balance formula, energy loss is 0.33 mm. · On average, the reduction in water level is 0.3 mm.

8. Assessment of Results The reduction in water level of 0.3 mm is very small in relation to the typical neap tidal range of 1.5 m or the spring tide range of 2.4 m. It also is small in relation to the monthly variation in sea level in Western Port which is determined from tide records at Stony Point to be +/- 150 mm/month.

Figure 4. Monthly Sea Level Variation at Stony Point WPB

The rise in sea level with time is not visually obvious in the tide measurements shown in Figure 4 but according to the United Nations Intergovernmental Panel on Climate Change (IPCC), the ocean in south-eastern Australia is rising at a rate of 1.8 mm/yr (see extract below from National Tide Centre (2015). Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 7 Crib Point Jetty

If, as reported by the IPCC, sea level is rising at 1.8 mm/yr, then the 0.3 mm reduction in water level that can be attributed to two vessels in port will be overcome in 9 weeks.

If the current CSIRO (2016) forecast of a 110 mm rise in sea level by the year 2030 is considered, then the 0.3 mm reduction in water level that can be attributed to two vessels in port will be overcome in 3 weeks.

9. Local Erosion There is expected to be local erosion of the seabed near the vessels due to the presence of the vessels causing a local acceleration of the water velocity. Other factors expected to cause erosion in the vicinity of the vessels are propeller wash (when the LNG carrier is underway) and propeller wash from tugs manoeuvring the LNG carrier. This erosion is a normal part of port operations, and expected to cause disturbance to the seabed within the port turning basin and within 150 m of the berth.

Another factor likely to cause local scour is the impact of the discharge from the FSRU reaching the seabed, as explored in Section 14 of the associated report on plume modelling (CEE, 2018). The water discharge will descend to the seabed with sufficient momentum to form a local depression in the seabed within the shipping berth. Plume calculations for the six-port discharge arrangement show that the discharge will have a downward velocity of approximately 0.22 m/s when it reaches the seabed. This will have negligible effect outside the shipping basin and will not impact on Ramsar values of Western Port.

10. Conclusion Overall, it is considered that there would be a very small reduction in water level in the upper part of Western Port due to the constriction in flow caused by any two ships berthed abreast at Crib Point. Based on two methods of calculation, the reduction in water level is estimated to be 0.3 mm.

This reduction is considered to be insignificant in relation to tidal and monthly variations in sea level in Western Port. In any event, rising sea level will counterbalance this reduction in 3 to 9 weeks.

Local erosion effects are expected due to the presence and operation of the FSRU and LNG carriers. The extent of disturbance will be to the seabed within the port turning basin and within 150 m of the berth. This is considered to be a normal part of port operations. The water discharge from the FSRU will also cause a local depression in the seabed within the shipping berth. This will have negligible effect outside the shipping basin and will not impact on Ramsar values of Western Port. Crib Point Gas Import Jetty Project – Effects of LNG Facility on Sea Level and Seabed at 8 Crib Point Jetty

11. References CEE (2018), “Plume Modelling of Discharge from LNG Facility – AGL Gas Import Jetty Project”. August 2018.

RJ Charbeneau and ER Holley (2001) “Backwater Effects of Bridge Piers in Subcritical Flows”, Research Report No 0-1805-1, Centre for Transportation Research, Univ of Texas at Austin.

CSIRO (2016), “Sea-level Rise, Observations, Projections and Causes”, CSIRO Oceanography, Hobart

K L Pun and S Law (2015) “Effects of Bridge Pier Friction on Flow Reduction in a Navigation Channel”, J Water Resources and Hydraulic Engineering, pp 326-331

National Tide Centre, BOM (2016) “Annual Sea Level Data Summary Report”, The Australian Baseline Sea Level Monitoring Project, Bureau of Meteorology

RH-DNV (2015) “Metocean Conditions at Existing Berths” Report to Port of Hastings