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 01_R01v03 - 4430 Peninsula Searoad Transport Pty Ltd | August 2016 Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Page 2 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 - 4430 Peninsula Searoad Transport Pty Ltd | August 2016 Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Page 3 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 01_R01v03 - 4430 Peninsula Searoad Transport Pty Ltd | August 2016 Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Page 4 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. 01_R01v03 - 4430 Peninsula Searoad Transport Pty Ltd | August 2016 Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Page 5 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. 01_R01v03 - 4430 Peninsula Searoad Transport Pty Ltd | August 2016 Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Page 6 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+) 01_R01v03 - 4430 Peninsula Searoad Transport Pty Ltd | August 2016 Searoad Ferries – Sorrento Terminal Upgrade Coastal Assessment Page 7 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.