Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment

Peninsula Searoad Transport Pty Ltd

August 2016

Document Status

Version Doc type Reviewed by Approved by Date issued V01 Draft EAL EAL 01/08/2016 V02 Final Draft EAL EAL 15/08/2016 V03 Final Report EAL EAL 23/08/2016

Project Details

Project Name Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Client Peninsula Searoad Transport Pty Ltd Client Project Manager Matt McDonald Water Technology Project Manager Elise Lawry Water Technology Project Director Christine Lauchlan Arrowsmith Authors TDG, PXV

Document Number 4430-01_R01V03

COPYRIGHT

Water Technology Pty Ltd has produced this document in accordance with instructions from Peninsula Searoad Transport Pty Ltd for their use only. The concepts and information contained in this document are the copyright of Water Technology Pty Ltd. Use or copying of this document in whole or in part without written permission of Water Technology Pty Ltd constitutes an infringement of copyright.

Water Technology Pty Ltd does not warrant this document is definitive nor free from error and does not accept liability for any loss caused, or arising from, reliance upon the information provided herein.

15 Business Park Drive Notting Hill VIC 3168

Telephone (03) 8526 0800

Fax (03) 9558 9365 ACN 093 377 283

ABN 60 093 377 283

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CONTENTS

1 INTRODUCTION 6 1.1 Proposed Development 6 1.2 Scope of Works 8

2 COASTAL PROCESSES ASSESSMENT 10 2.1 Site Details 10 2.2 Geomorphology 11 2.2.1 Port Phillip Bay 11 2.2.2 Current Geology and Shoreline Development 12 2.3 Coastal Processes 13 2.3.1 Wave Climate 13 2.3.2 Contemporary Shoreline Changes 17 2.3.3 Coastal processes 20 2.4 Shoreline Response to Sea Level Rise 20

3 COASTAL WATER LEVELS AND STORM TIDES 21 3.1 Costal Water levels 21 3.1.1 Mean Sea Level 21 3.1.2 Astronomical Tidal Planes 21 3.2 Storm Tides 22 3.3 Wave Setup 25

4 PRELIMINARY WAVE CONDITION ASSESSMENT 27 4.1 Design Wind Conditions 27 4.2 Design Wave Conditions 27

5 COASTAL HAZARD RISK ASSESSMENT 29 5.1 Overview 29 5.2 Coastal Inundation Hazard 29 5.3 Long-Term Coastal Recession 30 5.4 Short-Term Beach Erosion 30

6 MITIGATION OPTIONS 32

7 CONCLUSION 33

8 REFERENCES 34

9 DEFINITIONS AND DISCLAIMERS 34

APPENDICES

Appendix A Risk Assessment Definitions 01_R01v03

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LIST OF FIGURES Figure 1-1 Existing Sorrento Ferry Terminal (bottom image: Simon Pender Google+) 7 Figure 1-2 Proposed new Sorrento Ferry Terminal (bottom image: Peninsula Searoad Transport, 2016) 8 Figure 2-2 Project Settings and Geomorphologyical Features 10 Figure 2-1 Port Phillip region during the Early Pliocene (left) and Late Pleistocene (right). ( (Bird, 1990) 12 Figure 2-3 Port Phillip Bay Spectral Wave Model Domain and detail at Sorrento 14 Figure 2-4 South Channel Island long term Wind Climate 15 Figure 2-5 Sorrento Wave climate (significant wave height) adjacent to rock armour wall for pre (left) and post (right) development 16 Figure 2-6 Aerial Imagery 1935 to 2015 19 Figure 2-7 Bruun Rule Shoreline Response to Sea Level Rise (RisingSea.net) 20 Figure 3-1 Predicted MHHW Extent at Sorrento for Various Sea Level Rise Scenarios (Using 2009 DEM) 22 Figure 3-2 1% AEP Storm Tide Levels and Cross Section Location 24 Figure 3-3 Cross Section Profile and 1% AEP Storm Tide Levels 25 Figure 3-4 Wave set-up and run-up (CSIRO 2009) 26

LIST OF TABLES Table 1-1 Glossary 5 Table 3-1 Sea Level Rise Scenarios (VCC, 2014; DPCD, 2012) 21 Table 3-2 Estimate of High Water Levels for Different Sea Level Rise Scenarios 21 Table 3-3 1% AEP Storm Tide Levels Incorporating Mean Sea Level Rise Scenarios 23 Table 4-1 Hourly Design Wind Speed (m/s), Port Phillip Bay (AS 1170.2) 27 Table 4-2 Design Wave conditions – visitor pavilion 28 Table 4-3 Design Wave Conditions – adjacent to sea wall extension 28 Table 5-1 Coastal Inundation Risk Assessment Results 30 Table 5-2 Long Term Coastal Recession Risk Assessment Results 30 Table 5-3 Short Term Coastal Erosion Risk Assessment Results 31 Table 6-1 Suggested Climate Change Adaption Pathways 32 Table A-9-1 Likelihood Ranking 5.4-1 Table A-9-2 Consequence Ranking 5.4-1 Table A-9-3 Risk Assessment Matrix 5.4-1 Table A-9-4 Risk Profile Definition 5.4-1

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GLOSSARY AND DEFINITIONS

TABLE 1-1 GLOSSARY

AHD Australian Height Datum. 0 m AHD approximately corresponds to mean sea level. AEP Annual Exceedance Probability: The measure of the likelihood (expressed as a probability) of an event equalling or exceeding a given magnitude in any given year. Astronomical tide Water level variations due to the combined effects of the Earth’s rotation, the Moon’s orbit around the Earth and the Earth’s orbit around the Sun. Exceedance The probability of an extreme event occurring at least once during a prescribed probability period of assessment is given by the exceedance probability. The probability of a 1 in 100 year event (1% AEP) occurring during the first 25 years is 22%, during the first 50 years the probability is 39% and over a 100 year asset life the probability is 63%. Fluvial Geological term to describe sediments which are derived from a river environment. HAT Highest Astronomical Tide: the highest water level that can occur due to the effects of the astronomical tide in isolation from meteorological effects. Holocene Geological epoch beginning approximately 12,000 years ago. It is characterised by warming of the climate following the last glacial period and rapid increase in global sea levels to approximately present day levels. Hydro-isostasy Impact of addition or loss of water on the earth surface elevation. Lacustrine Geological term to describe sediments which are derived from a lake environment. MHHW Mean Higher High Water: the mean of the higher of the two daily high waters over a long period of time. When only one high water occurs on a day this is taken as the higher high water. MHWS Mean High Water Springs: the height of MHWS is the average, throughout a year when the average maximum declination of the moon is 23.5°, of the heights of two successive high waters during those periods of 24 hours when the range of the tide is greatest. Used when semi-diurnal tides are present. MSL Mean Sea Level: the long-term average level of the sea surface. Pleistocene Geological epoch from 2.5 million to 12,000 years before present that spans the earth's recent period of repeated glaciations and large fluctuations in global sea levels. Quaternary Geological period beginning approximately 2.6 million years ago and continuing today. Significant wave The average of the highest one third of all waves. height Storm surge The meteorological component of the coastal water level variations associated with atmospheric pressure fluctuations and wind setup. Storm tide Coastal water level produced by the combination of astronomical and meteorological (storm surge) ocean water level forcing.

Tuffs Soft and porous rock formation formed by the compaction of volcanic ash.

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1 INTRODUCTION

Water Technology was engaged by Searoad Ferries to undertake an assessment of the potential impacts on the coastal environment of their proposed Sorrento Ferry Terminal upgrade. The location and layout of the existing ferry terminal is shown below in Figure 1-1Error! Reference source not found..

The existing facility includes a small administration and entry house, a vehicle queuing zone and a small kiosk and souvenir hut adjacent to the ferry dock. The ferry terminal, including land reclamation for a small vehicle queuing zone, was established prior to the ferry service commencement in 1987. Upgrades to the terminal at Sorrento were completed in 1992 and again in 1995 when further land reclamation was undertaken to expand queuing zone and provide facilities for customers.

Major expansion of the loading and queuing zone to the present day condition was completed in 2002. The present day footprint of reclaimed land at the ferry terminal is in the order of 6,500 m2. 1.1 Proposed Development

The proposed expansion of the Sorrento Ferry Terminal includes the reclamation of a small section of land and construction of a new visitor pavilion adjacent to the docking area (Figure 1-2).

The reclamation involves the infilling adjacent to the coastline a section of seabed at the south-eastern end of the Ferry Terminal to allow for improved traffic flow. The reclaimed area will be protected by a rubble mound rock armour wall along the coast in an extension of the existing terminal seawall. The reclaimed area is approximately 90 m2. The 60m rock armour along the face of the reclaimed area will replace the existing rock armour and timber seawall and intersect at the existing shoreline with the stepped seawall currently under construction by DELWP.

The new visitor pavilion, placed in the lee of the existing jetty, will be constructed on pylons and be elevated above the water level. The proposed new development is presented in Figure 1-2.

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Vertical Timber Seawall, Ticket Booth presently being replaced by concrete step seawall by DELWP

Figure 1-1 Existing Sorrento Ferry Terminal (bottom image: Simon Pender Google+)

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Figure 1-2 Proposed new Sorrento Ferry Terminal (bottom image: Peninsula Searoad Transport, 2016)

1.2 Scope of Works

To assess the potential range and magnitude of impacts of the proposed upgrade, a preliminary coastal processes assessment, including assessment of the local wave climate for coastal processes and preliminary

feasibility design works was undertaken. A Coastal Hazard and Vulnerability Assessment (CHVA) was also

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completed to define the extent of existing coastal hazards and potential future coastal hazards associated with climate change and sea level rise at the ferry terminal.

Assessment of coastal processes has included a review of historical aerial imagery to establish the existing coastal processes regime, noting any changes or patterns in the change of beach width and/or beach vegetation. Preliminary wave modelling has been undertaken to provide an understanding of the relative impact of the new rock armouring along the reclaimed land adjacent to the shoreline on sediment transport.

The wave modelling has also been used to establish preliminary design wave conditions at the ferry dock for feasibility design of the visitor pavilion.

The CHVA assessment, a requirement of planning approval for development along the coast or Victoria, has been undertaken in accordance with the following advisory documentation and information:

 The Victorian Coastal Strategy (Victorian Coastal Council, 2014)

 The Victorian Coastal Hazard Guide (Department of Sustainability and Environment, 2012)

 Derivation of Revised Victorian Sea-Level Planning Allowances Using the Projections of the Fifth Assessment Report of the IPCC (Hunter, 2014)

 The Effect of Climate Change on Extreme Sea Levels in Port Phillip Bay (CSIRO, 2009)

 How to consider sea level rise along the Victorian Coast (Department of Sustainability and Environment, 2008)

 The Victorian Coastal Hazards Guide (Department of Sustainability and Environment, 2012)

 Planning Practice Note 53: Managing Coastal hazards and the Coastal Impacts of Climate Change (Department of Environment, Land, Water and Planning, 2015)

 Guidelines for Coastal Management Authorities: Assessing Development in Relation to Sea Level Rise (Depatment of Sustainability and Environment, 2012)

 Planning for sea level rise – Assessing development in areas prone to tidal inundation from sea level rise in the Port Phillip and Westernport Region (Melbourne Water , 2010)

 State Planning Policy Framework, Amendment VC94 Clause 13.01

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2 COASTAL PROCESSES ASSESSMENT 2.1 Site Details

The Queenscliff – Sorrento ferry links the two sides of Port Phillip Bay, ferrying pedestrians and vehicles across the entrance. The Sorrento terminal is located on the northern side of the Nepean Peninsula which stretches across the southern end of Port Phillip Bay. The terminal, along with the associated car park to the north are constructed on reclaimed land. Rock sea walls protect the terminal on all sides, and a vertical timber sea wall to the south is currently being replaced by an extension of the rock sea wall and the construction of concrete steps. The proposed expansions of the terminal, shown in Figure 1-2 includes reclamation of 90m2 of land, armoured by a rock wall and a pavilion in the lee of the existing jetty infrastructure.

The tidal range is relatively small at the site with a range of 0.7 m between the Mean Higher High Water (MHHW) and Mean Lower Low Water (MLLW) tidal planes. The site is exposed to locally generated wind waves from the north through to the east. The predominant sediment transport direction in the area is northwest to southeast.

Figure 1-1 illustrates the location of the Sorrento ferry terminal, and Figure 2-1 provides more details of the project setting. The pedestrian pier on the north-western side of the site has the highest elevation of the terminal at close to 2 m AHD. The site slopes down across the vehicle waiting lanes to a low point of around

1.1 m AHD on the eastern side.

FIGURE 2-1 PROJECT SETTINGS AND GEOMORPHOLOGYICAL FEATURES

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2.2 Geomorphology

To provide context to the coastal hazard vulnerability assessment and the potential risks posed by sea level rise to the Sorrento ferry terminal, a geological history of the formation of Port Phillip Bay, and the underlying geomorphology, and coastal processes in the vicinity of the terminal have been reviewed.

2.2.1 Port Phillip Bay

Pliocene Period

During the late Miocene (5.3 - 11.6 m.a.) through to the early Pliocene (3.6 - 5.3 m.a.), the embayment of the Port Phillip region was much larger and bound by the elevated ranges visible away from the present day shoreline, i.e. the You Yangs and the Dandenong, Otway, and Mornington Peninsula ranges (Figure 2-2 left).

Pleistocene Period

Through the Pleistocene Period (2.5 m.a. - 11,000 years ago) there was significant global climatic fluctuation during which several glacial phases (colder temperatures, increase in glacial and polar ice growth) and interglacial phases (warming of temperatures, melting of ice) occurred.

During the glacial phases water locked in the polar and glacial regions resulting in lower sea levels. Sands deposited on the bed during the interglacial periods were blown by the dominant north-westerly winds across the now dry coastal plain of Port Phillip region to form sand ridges across the south eastern area.

In the Late Pleistocene dune calcarenite had developed either side of the entrance, as seen at Point Lonsdale and the Nepean Peninsula, producing the present almost enclosed embayment.

Within the last glacial period of the Pleistocene, sea levels fell to as much as 120 m below the present day levels and the rivers of the Port Phillip region formed a single large river across the coastal plain, cutting a gorge through the dune ridges across the south, forming the present day “Rip” at the entrance to Port Phillip Bay (Figure 2-2 right).

Holocene Period

During the Holocene (the most recent geological epoch, beginning around 11,000 years ago), sea levels rose and flooded the Port Phillip region, creating a shoreline close the present day configuration of Port Phillip Bay. Sandy dunes formed along the Nepean Peninsula overlying the Pleistocene calcarenite.

Around 4,000 years ago, during the mid-Holocene, there was an increase in temperature and sea levels rose around 1-2 m above present day levels, creating shore platforms around Port Phillip Bay before falling back to present day levels. Emerged beaches provide evidence of this period of higher sea level at various locations

around the bay including at Sorrento.

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FIGURE 2-2 PORT PHILLIP REGION DURING THE EARLY PLIOCENE (LEFT) AND LATE PLEISTOCENE (RIGHT). ( (BIRD, 1990)

2.2.2 Current Geology and Shoreline Development

The Nepean Peninsula now has a dune topography, with unconsolidated Holocene dunes overlying Pliocene dune calcarenite. The calcarenite extends into the bay past Mud Island, and is visible east of Sorrento at The Sisters. A significant volume of sand exists in sand waves offshore from Sorrento on either side of South Channel.

The shoreline in the study area faces towards the north-east. Swell waves entering the Bay from Bass Strait would approach Sorrento from the north-west as they diffract into Port Phillip Bay, whilst locally generated wind waves could approach from the west through east-southeast. The primary direction of longshore sediment transport near the site is from the north-west to the south-east suggesting swell waves are the dominant force of sediment transport in the region.

Shoreline Development

The shoreline of Sorrento has been significantly modified, as illustrated in Figure 2-1. The ferry terminal is constructed on reclaimed land and surrounded by a rock armoured seawall.

To the west of the Ferry terminal is the Sorrento boat ramp. The boat ramp is protected from waves approaching from the north by a rock breakwater which continues as a seawall along the shore to the west providing protection to the carpark which is also on reclaimed land. A small breakwater on the south-eastern side of the boat ramp prevents sand from infilling the dredged boat ram area too rapidly.

Immediately south of the ferry terminal is a vertical timber wall which is currently being replaced by an extension of the rock breakwater and new concrete steps. There is no all tide beach present in front of the vertical wall, with the beach exposed at low tide but inundated during high tide. Landward of the seawall comprises a park

with a toilet block and memorial and The Esplanade. The existing timber seawall wall extends southeast to

the sandy beach, which continues curves to the east with varying amounts of vegetation.

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Beach Nourishment

A number of renourishment programs have been undertaken at Sorrento, including in 2014-15 when sand was dredged from sandbars offshore for renourishment near the sailing club. Further renourishment has been planned for Sorrento West in a current project.

2.3 Coastal Processes

As noted above, the net regional sediment transport is from northwest to southeast, driven by long period swells which diffract through The Rip into Port Phillip Bay. The ferry terminal provides protection of the adjacent beach from these swells and the proposed land reclamation area on the south-eastern edge of the site is impacted by the short period wind waves from the north through southeast. These wind waves have been reviewed to assess the impact of the proposed reclamation and rock wall extension on the coastline.

2.3.1 Wave Climate

The wave climate at the site was established by developing a spectral wave model using DEPI FutureCoast Coastal LiDAR. The modelling was carried out using DHI Software’s MIKE Spectral Wave (SW) model which is a new generation wind-wave model based on unstructured meshes.

The unstructured mesh, presented in Figure 2-3, allows the study area to be resolved in finer detail without causing excessive computational run times. The proposed visitor pavilion and a point adjacent to the proposed reclaimed land and rock armour wall are noted in the figure. The yellow line indicates the extent of the proposed land reclamation and rock armour wall.

The SW model has been calibrated to a number of locations within Port Phillip Bay and the model has been found to provide representative conditions around the Bay. Calibration has not been completed for conditions at Sorrento, however, for the purpose of this assessment further calibration is deemed unnecessary and

representative conditions at Sorrento are provided herein.

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Area of reclaimed land

FIGURE 2-3 PORT PHILLIP BAY SPECTRAL WAVE MODEL DOMAIN AND DETAIL AT SORRENTO

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The spectral wave model was run with representative wind speed, wind direction and water level conditions to establish a matrix relating wind climate to wave characteristics at the study area. The wind conditions measured at South Channel Island (BOM, 2014), and the predicted water levels at Williamstown (ANTT, 2016) were then used with a wave correlation matrix to provide a representative wave climate at the two sites.

Wind roses for the long term wind data (2002-2014) at South Channel Island and the summer (December to February) and winter (June-August) patterns are shown below in Figure 2-4. In general, a south, south-westerly winds dominant during summer and winds are predominantly north, north-westerly during winter months.

FIGURE 2-4 SOUTH CHANNEL ISLAND LONG TERM WIND CLIMATE

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The predicted wave conditions adjacent to the proposed reclaimed land and rock wall are shown below in Figure 2-5. Left and right columns demonstrate the wave conditions for pre-development (existing conditions) and post-development conditions respectively. Wave energy reflected by the existing and future coastal protection configurations are taken into consideration.

Pre development Post development Year round waves

Summer waves

Winter waves

FIGURE 2-5 SORRENTO WAVE CLIMATE (SIGNIFICANT WAVE HEIGHT) ADJACENT TO ROCK ARMOUR WALL

FOR PRE (LEFT) AND POST (RIGHT) DEVELOPMENT

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The predicted wave conditions illustrate a number of key points: - Conditions on site are typically calm, with over 80% of wave heights less than 0.1m; - Wave heights are limited by the shallow water and the short fetch across Port Phillip Bay to less than 0.6m; - Mud Islands and The Sands within southern Port Phillip Bay reduce wave energy at the Sorrento Ferry Terminal from wind generated waves from the north; - The site is protected from strongest winds from northwest and southwest due to its geographical location; - Waves are predominantly from the north-northeast to east direction with rare north-easterly waves reaching up to 0.9m in summer and easterly waves of up to 0.7m in winter; - Wave periods at the site are generally less than 6 seconds; - The land reclamation results in a small increase in modelled wave height adjacent to the seawall with the proportion of waves less than 0.1m significant decreasing by just over 1%. Further analysis of model results indicates the majority of the changed conditions occur during periods of lighter winds, and is a result of the closer proximity of the reporting point to the shifted wall in the developed conditions compared with the existing conditions (i.e. the small wind waves dissipate before they reach the monitoring point in the existing conditions but are reflected into the reporting point under developed conditions). - There is negligible change in the frequency or duration of higher waves with the addition of the reclaimed area and seawall in the model.

2.3.2 Contemporary Shoreline Changes

A number of aerial photographs of the Sorrento shoreline, taken between 1935 and 2015 have been collected and compared in Figure 2-6. These photographs illustrate the predominantly anthropogenic changes to the coastline in the vicinity of the Sorrento terminal. The 2015 shoreline (blue dashed line) and 1935 (yellow dashed line) shorelines are displayed on each figure to highlight the relative changes more obvious across the years presented. The red line represents the shoreline at the time of the image.

The 1935 and 1951 imagery shows a longer pier than what currently exists. It is shortened to the current length by 1957. These early images show the Sorrento sea baths which previously extended across the shallow bars offshore. The shallow bars can be observed in all images with rocks on the seabed visible in varying amounts depending on the sand coverage at the time of the image.

In 1957 the landward end of the jetty appears to be reinforced and the coastline to the northwest has changed alignment as material builds up on the northwestern side of the jetty.

In 1966 this area has continued to accrete and the sandy beach has become wider up to 100m northwest of the jetty. To the southeast of the jetty the beach the imagery suggests the beach near the sea baths has also accreted and a wider sandy area is noted.

Between 1971 and 1990 the sea baths are removed. The 1990 image also shows the increased footprint of the car parking around the jetty and the continued increase in beach width to the northwest. The beach to the southeast of the ferry terminal continues to accrete through the period from 1971 – 1990.

The 1995 imagery shows the construction of the Sorrento boat ramp and associated carpark on reclaimed

land to the northwest of the site. As noted previously, a spur breakwater was constructed along the beach to

ensure sand would not migrate to the ramp. Vegetation to the northwest of the jetty can be seen to extend seaward beyond the 1935 coastline indicating this area has become stable following development of the landward end of the jetty. This area of vegetation can be seen to increase by 2005 and the full footprint of the

01_R01v03 Ferry Terminal is shown. The beach to the northest of the terminal has cut back slightly adjacent to the terminal,

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however the offshore bars appear to have increased and less rock is visible in the offshore zone compared with 1995.

To the southeast of the Ferry Terminal the beach is similar to that shown in 1990 however vegetation along the back of the beach can be observed. This beach grass can be observed on site today and has acted to stabilise the dune at the back of the beach and continues to trap sand in these areas.

The Sorrento long pier at the redeveloped Sorrento Baths can be observed in 2005.

Little change in coastline, vegetation or offshore bars are observed in the images between 2005 and 2007. The sandy beach southeast of the Ferry Terminal appears to reduce slightly in width between 2007 and 2010. By 2015 the width of the beach has increased due to beach nourishment and the seaward limit of the sandy shoreline is similar to that observed in the 1990 image.

The extension of the terminal to the south east over a reclaimed area bordered by a rock sea wall is visible from the 2005 imagery and beyond. There is no evidence of significant changes to the shoreline alignment or nearshore bathymetry since the land reclamation associated with development of the terminal.

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4430 FIGURE 2-6 AERIAL IMAGERY 1935 TO 2015

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2.3.3 Coastal processes

As demonstrated by the analysis of imagery above, coastal processes at Sorrento adjacent to the ferry terminal are relatively low and appear to have reached an equilibrium. The gradual construction of the Ferry Terminal to the present day footprint has resulted in little observed change to the south east of the terminal. To the northwest a beach as established between the terminal and the Sorrento Boat Ramp, however the width of this beach has remained relatively consistent since construction of the boat ramp prior to 1995. Increased vegetation along the back of the beaches may continue to trap sand and lead to an increase in beach slope and reduction in sandy area for recreational use, however review of imagery has indicated that the position of the coastline has remained relatively stable across an extended period.

The wave climate at the beach adjacent to the proposed land reclamation area is low as shown in Figure 2-5, wave heights limited by the shallow bathymetry and fetch across Port Phillip Bay to the northeast and east and the protection offered by the Ferry Terminal to the north.

Wave modelling has indicated that the land reclamation and subsequent realignment of the ferry terminal at the shoreline, along with armouring of the seawall with rubble rock will have very little impact on wave conditions, and thus coastal processes along the shore. Waves which reach this area will be small and are likely to dissipate quickly resulting in little change to coastal processes.

2.4 Shoreline Response to Sea Level Rise On an undeveloped beach with a coastal dune forming the landward side of the coastal zone, sea level rise will result in erosion of the coastal dune and a landward shift of the beach profile, often quantified using the Bruun Rule (Bruun, 1962) as visualised in Figure 2-7. However, the coastline southeast of the ferry terminal at Sorrento is anchored in position by a (under construction) constructed concrete wall and rock seawall along the actual terminal. The shoreline is thus unable to adapt to increasing sea levels by migrating landward. Increasing sea levels will instead result in less exposed beach at the different tidal planes, and deeper water at the toe of the seawalls. The sandy beach to the northwest of the terminal is low, with a berm level of 1.5 to 2 m AHD. Behind the beach is a carpark located at around 2.0m AHD. There is no seawall or other back of beach protection at the carpark, and the carpark could therefore be at risk from coastal recession into the future.

Figure 2-7 Bruun Rule Shoreline Response to Sea Level Rise (RisingSea.net)

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3 COASTAL WATER LEVELS AND STORM TIDES 3.1 Costal Water levels

3.1.1 Mean Sea Level

Table 3-1 provides a summary of relevant sea level rise scenarios for planning. Estimates of sea level rise by Hunter (2014), incorporating the IPCC 2014 A1F1 climate change scenario, predict an increase in the mean sea level of 0.8 m by 2100. This scenario is considered to meet the minimum sea level rise scenario for planning as per the Victorian Coastal Strategy (2014).

TABLE 3-1 SEA LEVEL RISE SCENARIOS (VCC, 2014; DPCD, 2012)

Scenario and Year 2040 High 2070 High 2100 High Global Mean Sea Level 0.20 0.47 0.82 Rise (m)

3.1.2 Astronomical Tidal Planes

Astronomical tide refers to the rise and fall of the sea surface due to gravitational attraction between Earth, Moon and Sun. Water level variations in coastal areas due to the astronomical tide can be reliably predicted provided a reasonable length of continuous water level observations is available.

Tidal plane information was adopted as listed in the Victorian Tide Tables (Port of Melbourne, 2013). The Mean Higher High Water (MHHW) was taken from Sorrento Pier, and the Highest Astronomical Tide (HAT) has been taken from Williamstown. The Williamstown HAT was considered appropriate as the Williamstown tides are also diurnal and have a similar tidal range.

These levels have been combined with the applied sea level rise scenarios for the 2040, 2070, and 2100 shown in Table 3-1 and are listed in Table 3-2, rounded to 1 decimal place.

TABLE 3-2 ESTIMATE OF HIGH WATER LEVELS FOR DIFFERENT SEA LEVEL RISE SCENARIOS

m AHD Existing 2040 High 2070 High 2100 High Mean Sea Level - 0.20 0.47 0.8 Rise MHHW 0.4 0.6 0.9 1.2 HAT 0.5 0.7 1.1 1.3

The predicted extent of the MHHW tidal planes under existing, 2040, 2070 and 2100 sea level scenarios on the VicMap Coastal DEM topographical elevation (Department of Sustainability and Environment, 2009) are

shown in Figure 3-1 below. The steep sides of the terminal result in little additional inundation extent from the

2100 MHHW over the existing MHHW level.

A low area on the south eastern side of the reclaimed terminal area has an elevation below 1.2 m AHD,

equivalent to the 2100 (red) MHHW tidal plane. This area could be subject to ponding of water on the site,

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however a side entry pit has been located in this area to drain the terminal surface. Without the additional of a one-way valve on the stormwater pipe, this pit could be expected to surcharge under 2100 MHHW conditions. The MHHW tidal plane could be expected to be exceeded 50% of the time, and inundation of this area could thus be expected approximately half the days of the year by 2100 without mitigation.

The area of reclamation under this present proposal is assumed to be level with the roadway surrounding, and thus is above the existing and future MHHW tidal plane and not subject to tidal inundation.

FIGURE 3-1 PREDICTED MHHW EXTENT AT SORRENTO FOR VARIOUS SEA LEVEL RISE SCENARIOS (USING 2009 DEM) 3.2 Storm Tides

The term storm tide refers to coastal water levels produced by the combination of astronomical and meteorological ocean water level forcing. The meteorological component of the storm tide is commonly referred to as storm surge and collectively describes the variation in coastal water levels in response to atmospheric pressure fluctuations and wind setup.

Estimates of extreme coastal water levels have been developed for Port Phillip Bay by the CSIRO (2009) for various planning and sea level scenarios. The storm tide levels for Sorrento have been adopted for this study and are presented in Table 3-3, based on the Climate Change Scenario 2 which combines sea level rise (IPCC

2007 A1F1) with an increase in wind speeds of 19% by 2100. The value for “Existing” is from the report, now

7 years old, and the value for 2040 has been linearly interpolated between the reported 2030 and 2070 values.

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Melbourne Water also refers to a 100 year flood level for Port Phillip Bay which has not been adopted for this study as the Melbourne Water levels are deemed applicable for residential or commercial buildings rather than extension of a seawall.

TABLE 3-3 1% AEP STORM TIDE LEVELS INCORPORATING MEAN SEA LEVEL RISE SCENARIOS

m AHD Existing 2040 High 2070 High 2100 High 1% AEP 1.3 1.4 1.7 2.1

The potential extents of inundation from the predicted 1% AEP storm tides on the existing footprint are displayed in Figure 3-2 below. The cross section profile shown in Figure 3-3 also helps to illustrate the typical existing topography of the seafloor and ferry terminal in relation to storm tide levels.

These figures suggest that under the existing 1% AEP storm tide, a small section of the south eastern side of the site would be inundated across both exit lanes. A small increase in inundation area is expected by 2040. The proposed new area of reclamation (if built to surrounding levels) would not be inundated by the 2040 storm tide.

By 2070, the 1% AEP storm tide is expected to inundate most of the site, and sit just above the floor level of the ticket booth office (1.68 m AHD). The proposed new area of reclamation (if built to surrounding levels) would not be inundated by the 2070 storm tide, however it may be surrounded by inundated roadway during the peak of the storm. The footpath along the north western edge would remain above the 2070 1% AEP storm tide level, but may be impacted by waves and spray.

The whole site is projected to be inundated by the 1% AEP storm tide by the end of the century, with inundation extending along The Esplanade to the southeast of the site behind the current vertical timber sea wall. The depth of inundation of the ticket booth office and across the waiting lines would be greater 0.4 m. Inundation is expected to be transient and peak storm tide levels will reduce with the ebb tide and the site is expected to be inundated for a number of hours rather than days. The proposed new area of reclamation (if built to surrounding levels) would also be inundated by the 2100 storm tide, however, as with the rest of the site, this inundation would be limited to the peak of the storm tide and assuming free drainage of the site is included in

design, water should not pool in the reclaimed area.

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FIGURE 3-2 1% AEP STORM TIDE LEVELS AND CROSS SECTION LOCATION

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FIGURE 3-3 CROSS SECTION PROFILE AND 1% AEP STORM TIDE LEVELS

3.3 Wave Setup

The action of waves, both in terms of their erosive capacity and their contribution to coastal water levels, are considered coastal hazard risks at the Sorrento ferry terminal. The impact of the development on coastal

processes has been assessed in Section 2.3.

To enable estimation of the contribution of wave action in the nearshore zone to local coastal water levels, an

estimate of design wave conditions on the coastline in the vicinity of the project area has been undertaken in

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Section 4 below. Wave setup and the height and extent of wave run-up contribute to the total water level as shown in Figure 3-4.

Design wind wave conditions for Sorrento have been established in Section 4.2 and are presented in Table 4-3. The shoreward flux of water resulting from breaking waves of this height has been estimated as potentially resulting in an additional hydrostatic pressure increases at the immediate shoreline of approximately 0.4 m above the mean water level. As the waves will be approaching the sea wall rather than a sloped beach, wave run-up is not considered.

FIGURE 3-4 WAVE SET-UP AND RUN-UP (CSIRO 2009)

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4 PRELIMINARY WAVE CONDITION ASSESSMENT

As discussed in Section 2.3, a spectral wave model of Port Phillip Bay has been used to review the wave conditions at the Sorrento Ferry Terminal. Water Technology maintains a spectral wave model of Port Phillip Bay to undertake coastal and oceanographic condition assessments around the Bay. The model has been calibrated to other locations around the Bay and is considered to provide a good representation of conditions at Sorrento. However, it should be noted that the wave model has not been verified to conditions at Sorrento and data from the model should be considered preliminary and for information only.

Preliminary design wave conditions have been derived using design wind conditions and extreme water levels within Port Phillip Bay. 4.1 Design Wind Conditions

Design wind conditions have been derived from the Australian Standards AS 1170.2 Structural Design Actions for Region 5 (Port Phillip) by Atkins (2015). The design wind conditions are provided as 3 second gusts. These have been converted to hourly wind speeds more appropriate for considering wave growth across open water. The design wind conditions for a 1 year Average Return Interval (ARI) event and a 50 year ARI event are shown

Table 4-1 Hourly Design Wind Speed (m/s), Port Phillip Bay (AS 1170.2)

ARI N NNE NE ENE E ESE SE

1 22.4 20.7 19.0 18.5 17.9 17.9 17.9

50 25.3 23.4 21.5 20.9 20.3 20.3 20.3

4.2 Design Wave Conditions

The 1 year ARI design wind conditions have been combined with the 1 year ARI water level conditions to determine the serviceability limit state, or the 1 year ARI conditions. The ultimate limit state has been defined as the combination of 50 year ARI wind conditions and the 100 year ARI water level, equivalent to around a 200 year ARI storm event. These conditions have also been simulated under potential future sea level states in 2100. Future extreme water levels presented in Table 3-3 have been considered for 2100.

The design wave conditions at the visitor pavilion are presented in Table 4-2. The design wave conditions adjacent to the proposed extension of the rock armour wall are presented in Table 4-3 for pre and post development conditions. The wave conditions shown are for the maximum wave height at the model point. Wave conditions in the immediate vicinity may differ slightly from this point.

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Table 4-2 Design Wave conditions – visitor pavilion

50 year ARI 100 year ARI Visitor pavilion Wind Wind Speed Water Level Direction: E (m/s) (m AHD) Hs (m) Tp(s)

Present-day 20.3 0.99 0.9 3.7 2015

Future 2100 20.3 2.10 1.1 4.2

Table 4-3 Design Wave Conditions – adjacent to sea wall extension

Wind 50 year ARI 100 year ARI Existing Developed Adjacent to rock Adjacent to rock armour Direction: Wind Speed Water Level East armour wall wall NorthEast (m/s) (m AHD) Hs (m) Tp(s) Hs (m) Tp(s)

Present-day 20.9 0.99 0.8 4.8 0.8 4.9 2015

Future 2100 20.9 2.10 1.2 4.5 1.2 4.5

Design armour rock

Van der Meer’s empirical formula was applied to provide a preliminary assessment of the rock armour parameters of the rock armour at the reclamation area and determine the nominal median diameter (Dn50) of the rock.

Van der Meer’s formula takes into account the wave parameters, slope angle of seabed and the structure, rock density, storm duration and seawater density. Based on the wave parameters at the site, the formula for plunging waves was applied. Calculation results indicate a rock size with a Dn50 in the range of 0.25 to 0.35m and a weight range of 70-75 kg to be suitable for the study site in achieving a stable rock armour given the wave climate. It should be noted that the results are indicative and for information only.

Larger rock armour may be preferred to provide a consistent appearance with the existing rock wall where armour rock is considerably larger. Increased armour rock may also reduce the incidence of vandalism (theft or shifting) due to the (relatively) lightweight rock required for the design wave climate at the reclamation area.

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5 COASTAL HAZARD RISK ASSESSMENT 5.1 Overview

Risk Management is the term applied to a logical and systematic method of establishing the context, identifying, analysing, evaluating, treating, monitoring and communicating the risks associated with any activity, function or process in a way that will enable organisations to minimise losses and maximise opportunities (Standards Australia, 2004). Risk is identified as the product of the likelihood and consequence of an event impacting on an asset or objective.

Risk profiles have been developed by assigning scores to the consequence of each relevant coastal hazard and the likelihood of this coastal hazard impacting the site over a range of relevant timeframes this century. The risk profile is determined by applying the scores to a risk matrix such as the one shown in Table A-9-3, Appendix A. The risk profile assists with the identification and analysis of priority risks for subsequent decision making and planning.

Table A-9-1 within Appendix A displays a description and semi-quantitative score that has been assigned to the range of coastal hazard likelihoods.

Table A-9-2 within Appendix A displays a description and semi-quantitative score that has been assigned to the range of coastal hazard consequences.

Table A-9-3 and Table A-9-4 within Appendix A display the resulting risk matrix and risk profile definitions respectively. 5.2 Coastal Inundation Hazard

The likelihood and consequence of the coastal inundation hazards impacting the Sorrento Ferry Terminal has been assessed based on the review of the storm tide levels and existing topography. Risks ratings for the coastal inundation hazard are provided in Table 5-1.

The key justifications for the risk ratings assigned for this hazard are provided below:

 It is assumed the reclaimed land is to be built at the same level as the surrounding pavement and be designed to allow for drainage of water on the site.

 It is assumed that the ferry would not function during a significant storm event and the facility would not be used during a storm event. Inundation of the car parking area for a short duration during a storm tide is unlikely to have significant impact.

 Breaking waves in the near shore may produce a localized increase in water level of 0.4 m.

 The current 1% AEP storm tide level would inundate a small area of the exit lanes of the ferry terminal to a depth of less than 0.3 m. This flooding would result from surcharging from a side entry pit. By 2040 the depth of this inundation would be close to 0.3 m adjacent to the drainage pit.

 By 2070, the ticket booth and the majority of the waiting lanes would be inundated by the 1% AEP storm tide, with a maximum depth in the exit lanes of around 0.6 m.

 By 2100, the whole site, including the area of reclaimed land, is projected to be inundated by the 1% AEP

storm tide, as well as access via the Esplanade to the south.

 Damage resulting from the short duration of these inundation events would be impacted by the drainage

of the water from the site after the event.

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TABLE 5-1 COASTAL INUNDATION RISK ASSESSMENT RESULTS

Coastal Specific Impact Timeline Likelihood Consequence Risk Hazard Rank Coastal Inundation of the site or its access Existing Possible Insignificant Low Inundation by elevated storm tide and 2040 Likely Insignificant Low additional elevated water levels associated with wave action on the 2070 Likely Minor Medium coastline. 2100 Likely Minor Medium

5.3 Long-Term Coastal Recession

The likelihood and consequence of long term coastal recession hazards at the site has been assessed based on the review of the coastal and oceanographic processes expected to impact the property this century. The key justifications for the risk ratings assigned for this hazard in Table 5-2 are provided below:

 The shoreline around the Sorrento terminal is protected by hard structures, including rock and concrete step breakwaters.

 In place of recession of the shoreline, it is likely that the depth of water at the edge of the terminal will increase, thus allowing larger waves to break on the seawalls.

 Wave heights at the shoreline are limited by the protection offered by the Ferry terminal, Mud Island and The Sands and the wide shallow area offshore of the beach.

 Wave energy over time may lead to damage of the seawalls. If maintenance of the seawalls is not carried out seawalls could (in the extreme case) collapse. This may lead to recession of the shoreline in localised areas which could impact the function of the ferry terminal.

TABLE 5-2 LONG TERM COASTAL RECESSION RISK ASSESSMENT RESULTS

Coastal Specific Impact Timeline Likelihood Consequence Risk Hazard Rank Coastal Long term coastal recession. A Existing N/A N/A N/A Inundation sustained and progressive erosive 2040 Rare Minor Low recession of the high tide water mark on the coastline that impinges 2070 Rare Moderate Low upon the site or its access and may expose the site to more frequent 2100 Unlikely Moderate Medium and significant coastal inundation.

5.4 Short-Term Beach Erosion

The likelihood and consequence of short term erosion hazards impacting the site has been based on the review of the coastal and oceanographic processes expected in the study area this century. The key

justifications for the risk ratings assigned for this hazard in Table 5-3 are provided below.

 The shoreline around the Sorrento terminal and adjacent coastline is protected by rock sea walls and a

stepped concrete seawall.

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 The water depth at the sea walls is expected to increase through the century with sea level rise due to a lack of sediment to adjust the profile as per the Bruun Rule. This will expose the sea walls to the direct action of breaking waves.

 Wave heights are generally small, particularly inshore at the new land reclamation area.

 The existing 1% AEP storm tide exceeds the level of the south eastern side of the terminal. By the end of the century the whole terminal is projected to be inundated by the 1% AEP storm tide.

 Additional wave induced water levels of 0.4 m may be present above this, along with over-wash and spray. Waves breaking across the structure will result in a sudden energy dissipation resulting in higher water levels. Without maintenance of the rock wall to repair any damage sustained during storm events local consequences around the damaged wall could occur.

 It is assumed that the rock wall has been designed to withstand the 2060 1% AEP storm conditions, providing a 50 year design life for the Ferry Terminal. Beyond this window, maintenance of the seawall may be required on a more regular basis in the future to prevent short term storm damage.

TABLE 5-3 SHORT TERM COASTAL EROSION RISK ASSESSMENT RESULTS

Coastal Specific Impact Timeline Likelihood Consequence Risk Hazard Rank Coastal Short term beach erosion. Existing Possible Moderate Medium Inundation Dynamic, short term recession or Medium breach of the dune or barrier 2040 Possible Moderate system by wave action and 2070 Possible Moderate Medium elevated water levels that impacts the site and may expose the site to 2100 Likely Major High potentially more significant coastal inundation.

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6 MITIGATION OPTIONS

There is a wide array of potential mitigation options that can be employed in response to climate change and sea level rise risks to coastal infrastructure and assets. The National Committee on Coastal and Ocean Engineering (2012) endorses a simple set of three broad strategic options for mitigating the impact of sea level rise as presented by the IPCC. These options are considered to provide a basic framework for the assessment of potential mitigation strategies for the site if and when they are required.

The three broad strategic options are retreat, accommodate and protect. These broad strategic options have been used to provide the suggested pathways listed in Table 6-1 to adapting to the coastal hazard risks identified at the site.

It is noted that the Ferry Terminal will experience inundation during extreme storm events. The inundation is likely to be limited in spatial extent until the 2070 window at which point much of the site may become inundated. Inundation of the site is not considered a major risk to the function as ferry’s are unlikely to be operating during this period and the site will be uninhabited. Post inundation engineering checks should be considered to ensure drainage pathways are cleared and pooled water has not caused any damage to the reclaimed land.

The design conditions of the extended rock wall have been presented for the 100 year ARI conditions at present day and year 2100. Design waves are small at the rock wall extension and thus the design rock is also relatively small, particularly when compared with the larger rock within the existing rock wall along the ferry terminal. Larger rocks will reduce the likelihood of vandalism (through shifting of smaller, lighter rocks by people), provide a smooth visual transition to the existing wall and increase the design life of the rock wall extension.

TABLE 6-1 SUGGESTED CLIMATE CHANGE ADAPTION PATHWAYS

Planning Suggested Response Suggested Mitigation Measures Horizon Strategy Existing None required Assess potential for a tidal flap on stormwater pipe which drains ferry terminal to prevent back flow during extreme tide levels 2040 Accommodate Consider installing a tidal flap on stormwater pipe which drains ferry terminal to prevent backflow during extreme tide levels Repair any damage to rock wall 2070 Accommodate Review and repair any damage resulting in inundation of terminal during extreme tide levels Repair any damage to rock wall 2100 Accommodate Review and repair any damage resulting in inundation of terminal during extreme tide levels Repair any damage to rock wall. Consider increasing rock size if repair is required frequently

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7 CONCLUSION

The conclusions relating to the coastal hazard vulnerability assessment of the Sorrento terminal site are considered as follows:

 The Sorrento terminal is located in Port Phillip Bay, on the northern side of the Nepean Peninsula.

 The peninsula is composed of Holocene sand dunes overlying Pleistocene calcarenite.

 The predominant direction of sediment transport at the site is from the north-west to the south-east.

 The tides and wave climate are significantly reduced in the bay around Sorrento.

 The terminal is constructed on reclaimed land surrounded by rock breakwater.

 The coast to either side of the terminal is highly modified, with a rock breakwater and boat ramp to the northwest, and rock breakwater and concrete step sea wall being constructed to the southeast.

 The current development proposal includes reclamation of 90m2 of land adjacent to the site in the southeast corner. Rock armour along the existing ferry terminal will continue along the reclaimed land to the coastline. A visitor pavilion will be located offshore in the lee of the existing jetty infrastructure.

 Little change is visible in the beach shapes and sand distribution from aerial imagery dating back to 1935, with the exception of the coastal developments. The beach alignment immediately to the northwest of the terminal appears to have rotated clockwise after the construction of the boat ramp further to the west.

 The existing and developed site is not considered to be subject to Bruun type coastal recession due to the presence of rock breakwaters, thus the depth of water at the toe of those structures is expected to increase in response to sea level rise.

 The existing 1% AEP storm tide level would inundate a small area on the south-western side of the terminal existing. By 2070 the 1% AEP storm tide would inundate most of the existing site and be above the floor level of the ticket booth. By 2100 the whole site, including new area of reclamation, would be inundated, along with The Esplanade to the south west restricting access to the site. People and vehicles would not be expected to be present at the site during a significant storm event.

 The risk of short term erosion to the existing and developed site is limited by the rock breakwaters surrounding the terminal. Assuming these have been built to withstand the 1% AEP storm events reduces the likelihood of serious damage to the site to below “possible” (i.e. the likelihood is less than 1:100).

The impact of the proposed land reclamation, rock armour wall and visitor pavilion is likely to be low. The coastal processes are unlikely to be impacted by the realignment of the rock armour wall adjacent to the shoreline. Inundation of the reclaimed land will be limited to during the peak of storm tide events in 2100.

Design of the proposed visitor pavilion can be completed to ensure inundation during storm tide events does not occur. The visitor pavilion will have little impact on coastal processes.

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8 REFERENCES Akins Maritime Engineering. (2015). Sorrento Timber Seawall Coastal Design Report. Sandringham: Atkins Maritime Engineering. Bird, E. (1990). The Sandringham Environment Series, No. 8 Structure and Surface – The Geology and Geomorphology of the Sandringham District. Melbourne: City of Sandringham in consultation with its Natural Environment Advisory Group. Bird, E. (1993). The Coast of Victoria – the shaping of scenery. Melbourne: Melbourne University Press. Bird, E. (2011). Changes on the Coastline of Port Phillip Bay. Melbourne: Department of Sustainability and Environment. CSIRO. (2009). The Effect of Climate Change on Extreme Sea Levels in Port Phillip Bay. Melbourne: CSIRO. Department of Environment, Land, Water and Planning. (2015). Planning Practice Note 53: Managing Coastal hazards and the Coastal Impacts of Climate Change. Melbourne: The State of Victoria. Department of Sustainability and Environment. (2008). How to consider sea level rise along the Victorian Coast . Melbourne: The State of Victoria. Department of Sustainability and Environment. (2009). VicMap Elevation Data. Melbourne: The State of Victoria. Department of Sustainability and Environment. (2012). The Victorian Coastal Hazard Guide. Melbourne: The State of Victoria. Department of Sustainability and Environment. (2012). The Victorian Coastal Hazards Guide . Melbourne: The State of Victoria. Depatment of Sustainability and Environment. (2012).  Guidelines for Coastal Management Authorities: Assessing Development in Relation to Sea Level Rise . 2012: The State of Victoria. Hunter, J. (2014). Derivation of Revised Victorian Sea-Level Planning Allowances Using the Projections of the Fifth Assessment Report of the IPCC. Melbourne: CSIRO. Melbourne Water . (2010). Planning for sea level rise – Assessing development in areas prone to tidal inundation from sea level rise in the Port Phillip and Westernport Region. Melbourne: Melbourne Water Corporation. National Committee on Coastal and Ocean Engineering. (2012). Guidelines for Responding to the Effects of Climate Change in Coastal and Ocean Engineering. Melbourne: Engineers Australia. Port of Melbourne. (2013). Victorian Tide Tables, 88th Edition 2013. Melbourne: Port of Melbourne Corporation and the Victorian Government. Victorian Coastal Council. (2014). The Victorian Coastal Strategy. Melbourne: VCC.

9 DEFINITIONS AND DISCLAIMERS

The information contained in this report is subject to the disclaimers and definitions below.

1. The area referred to in this report at the development “site” or “property” is the land that Water Technology believes most closely represents the location identified by the client. The identification has been done in good faith and in accordance with information given to Water Technology by the client.

2. No warranty is made as to the accuracy or liability of any studies, estimates, calculations, opinions, conclusions, recommendations (which may change without notice) or other information contained in this report, and to the maximum extent permitted by law, Water Technology disclaims all liability and responsibility for any direct or indirect loss or damage which may be suffered by any recipient of other person relying on anything

contained in or omitted from this report.

3. This report has been prepared for the sole use by the Client as stated on page 2 and no responsibility is accepted by Water Technology with regard to any third party use of the whole, or of any part, of the contents

of this report. Neither the whole or any part of this report, or any reference there to, may be included in any

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document, circular or statement without Water Technology’s written approval of the form and context in which it would appear.

4. The information provided represents the best estimates based on currently available information described. This information is subject to change as new information becomes available and as further studies area carried out.

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APPENDIX A RISK ASSESSMENT DEFINITIONS

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TABLE A-9-1 LIKELIHOOD RANKING

Likelihood Level Description Annual Exceedance Probability 1 – Rare Risk will occur in exceptional circumstances. 1:10,000 2 – Unlikely Risk not likely to occur within the period. 1:1,000 3 – Possible Risk may occur within the period. 1:100 4 – Likely Risk likely to occur within the period. 1:10 5 – Almost Certain Risk will occur within the period. 1:1

TABLE A-9-2 CONSEQUENCE RANKING

Consequence Level Description 1 – Insignificant Minimal impact in a localised area within existing natural variability. 2 – Minor Low impact in a localised area with minimal impact to the site or its function. Flood depths <0.3m. 3 – Moderate Medium impact in a broad area with minor, local consequences to the site or its function. Flood depths 0.3 – 0.6m. 4 – Major High impact in a broad area resulting in significant consequence to the site or its function. Flood depths 0.6 – 1.2m. 5 - Extreme Very high impact with broad and significant consequences to the site and its function. Flood depths > 1.2m.

TABLE A-9-3 RISK ASSESSMENT MATRIX

Likelihood Consequence 1 – Insignificant 2 – Minor 3 – Moderate 4 – Major 5 – Extreme 5 – Almost Certain Medium Medium High Extreme Extreme 4 – Likely Medium Medium Medium High Extreme 3 – Possible Low Medium Medium Medium High 2 – Unlikely Low Low Medium Medium Medium 1 – Rare Low Low Low Medium Medium

TABLE A-9-4 RISK PROFILE DEFINITION

Risk Profile Definition Low Tolerable risk. A level of risk that is low and manageable without intervention. Medium A level of risk that may require intervention to mitigate. High A level of risk requiring significant intervention to mitigate.

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Melbourne Brisbane 15 Business Park Drive Level 3, 43 Peel Street Notting Hill VIC 3168 South Brisbane QLD 4101 Telephone (03) 8526 0800 Telephone (07) 3105 1460 Fax (03) 9558 9365 Fax (07) 3846 5144

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