Department of Sustainability & Environment Review of Beach Nourishment Priorities for Port Phillip Bay Volume 1 - Main Report
April 2008
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay Volume 1 • Main Report Contents
1. Introduction 2
2. Background 4
3. Methodology 6 3.1 General 6 3.2 Review Reports 6 3.3 Beach Selection Criteria 6 3.4 Prioritising Criteria 7 3.5 Visual Inspection 7 3.6 Prioritise the Nourishment Projects 7 3.7 Determine Sand Demands and Quantities 8 3.8 Asset Register 8
4. Beach Assessment Criteria 10 4.1 General 10 4.2 Technical Criteria 10 4.3 Draft Social and Economic Criteria 11 4.4 Workshop 11 4.5 Final Social and Economic Criteria 12 4.6 Final Agreed Criteria 13 4.7 Scoring 14
5. Beach Assessment 16 5.1 Candidate Sites 16 5.2 Site Inspections 18 5.3 Assessment by Bayside Municipalities 19
6. Assessment Results 22 6.1 Technical Assessment 22 6.2 Social and Economic Assessment 24
7. Beach Priorities 26 7.1 General 26 7.2 Applying and Refining Social and Economic Assessment 26 7.3 Final Priority List 26
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay Volume 1 • Main Report 8. Sand Sourcing Analysis 30 8.1 General 30 8.2 Beaches at Risk Study 30 8.3 Channel Deepening as a Source of Nourishment Sand 31 8.4 Other Potential Sources of Sand 34 8.5 Feasibility of Searching for Offshore Sand Sources 37
9. Concept Design of High Priority Sites 40 9.1 Altona 40 9.2 Elwood 41 9.3 Mt Martha North 42 9.4 Portarlington 44 9.5 North Aspendale 44 9.6 Half Moon Bay 45 9.7 Eastern Beach Geelong 46 9.8 Scope of Work 46 9.9 Asset Register 47
10. Conclusions 48
11. Recommendations 50 11.1 Implementation 50 11.2 Sand Sourcing 50 11.3 Stabilisation Works 50
Table Index Table 1 Social and Economic Scoring and Comments Provided by DSE 20 Table 2 Technical Criteria Scoring 23 Table 3 Technical Ranking of the Beaches 24 Table 4 Summary of Final Beach Rankings 28 Table 5 Dredging Costs 35 Table 6 Altona Beach Coastal Management Options (Coastal Engineering Solutions, 2003) 41 Table 7 Mt Martha North Beach Coastal Management Options (Coastal Engineering Solutions, 2007) 43 Table 8 Scope of Work 46 Table 9 Beach Rankings 48
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay Volume 1 • Main Report Figure Index Figure 1 Location of sites in Port Phillip Bay 18 Figure 2 East End of Altona Beach 40 Figure 3 West End of Altona Beach 40 Figure 4 Elwood Beach View South 42 Figure 5 Elwood Beach View North 42 Figure 6 Mt Martha North Beach 43 Figure 7 Beach Erosion 43 Figure 8 Portarlington Beach 44 Figure 9 Cliff Damage 44 Figure 10 Sand Bag Erosion Protection 45 Figure 11 North Aspendale Beach 45 Figure 12 South End of Half Moon Bay 45 Figure 13 Half Moon Bay Beach 45 Figure 14 Eastern Beach 46 Figure 15 Eastern Beach 46
Appendices A References B Project Brief C Example Site Inspection Report Sheet D Site Inspection Reports E Complete Criterion Matrix F Asset Register Output
Volume 2 – Detailed Site Photographs
Cover photos: NASA, GHD
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay Volume 1 • Main Report 31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 1 Volume 1 • Main Report 1. Introduction
In November 2006, the Victorian Government announced an allocation of $8 million over four years for the establishment of the Enhancing Our Beaches Program, which will deliver a range of nourishment projects around Port Phillip Bay over the next four years. The Department of Sustainability and Environment (the Department) has engaged GHD Pty Ltd (GHD) to conduct a review of previously identified nourishment projects, which is presented in this report. The objective of this Review is to provide a sound technical and social basis for assessing and prioritising the allocation of Enhancing Our Beaches program funding for beach nourishment projects around Port Phillip Bay, by:
» updating the findings of the Beaches at Risk study of 2001; and
» reviewing and updating the priority list for beach nourishment projects around Port Phillip Bay. The Beaches at Risk study required modifications to the recommendations to take into account works completed since 2001, reassess sand sourcing in light of the forthcoming Channel Deepening project and take into account other recent beach nourishment projects.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 2 Volume 1 • Main Report 31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 3 Volume 1 • Main Report 2. Background
There were 25 beaches nourished around Port Phillip Bay during the 1970s and 1980s to protect natural and built coastal assets and other infrastructure from damage caused by coastal erosion. These and other Port Phillip Bay beaches have become highly valued recreational assets for the Victorian community. The Department of Sustainability and Environment (DSE) is responsible for the periodic maintenance of nourished and high risk beaches around Port Phillip Bay. In 2001 the Department commissioned the Beaches at Risk study to assess the condition of the 25 nourished beaches. The study found that most of the beaches would require some form of reconstruction and/or maintenance within 5 to 10 years from the time of the study (i.e. 2006 to 2011). Furthermore, this study assessed 18 more beaches which were identified as posing a risk of damage to public facilities, were characterised by unstable cliffs or would benefit by improving amenity, and where nourishment was identified as being a possible repair/rectification measure for these problems. The Association of Bayside Municipalities (ABM) also engaged in an exercise in preparing a set of social and economic criteria for selecting beaches for nourishment, which was reported by their consultant Reckon Pty Ltd (Reckon) in their report, Port Phillip Coast and Marine Planning Program, Sept 2001. After the release of the Beaches at Risk report, a priority list of beach nourishment projects within Port Phillip Bay was agreed upon with key stakeholders and endorsed by the then Minister for Environment. Some minor nourishment works have already been undertaken and delivery has commenced for major beach nourishment projects at Middle Park and Sandringham. Preliminary designs have also been prepared for Elwood, Brighton, Mentone, Altona, Eastern Beach, Moorpanyal, St Helens and Rippleside. In November 2006, the Victorian Government announced an allocation of $8 million over four years for the establishment of the Enhancing Our Beaches Program, which will deliver more nourishment projects around Port Phillip Bay over the next four years. This review has considered 30 beach sites, accounting for a number of the original 43 identified sites which have since received some remedial attention, or which have since been considered as lower in priority than was suggested in 2001.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 4 Volume 1 • Main Report 31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 5 Volume 1 • Main Report 3. Methodology
3.1 General Section 4 of the Project Brief (included in Appendix B) provides an outline scope of services for this project. The tasks undertaken in fulfilling the requirements of this scope were:
» Review previous reports;
» Review and confirm beach selection criteria;
» Develop criteria for prioritising actions (with DSE);
» Host a Workshop with ABM and DSE, with focus on social aspects;
» Conduct visual inspections of all nominated beaches and complete site reports;
» Prioritise beach projects with agreed criteria;
» Determine sand quantities for each project;
» Assess other infrastructure for each project;
» Develop an asset register for priority projects;
» Prepare study report; and
» Present study to DSE.
3.2 Review Reports A number of reports and studies have been reviewed, and are listed in Appendix A, References. In particular, this review focuses on the Beaches at Risk Final Report (Vantree, 2001). The Port of Melbourne Corporation’s Channel Deepening Project is an additional source of useful information, especially in relation to understanding the coastal processes operating in Port Phillip and the potential for securing suitable sources of sand from this dredging for beach nourishment around Port Phillip Bay. We have drawn relevant information from both the Environmental Effects Statement (2004) and the Supplementary Environmental Effects Statement (2007).
3.3 Beach Selection Criteria The Reckon report prepared for the Association of Bayside Municipalities in September 2001 sets out both social and economic criteria for assessing and selecting beach renourishment projects. The preparation of these criteria included extensive consultation and research, giving this work sound credibility. The report does, however, note that technical, functional and environmental considerations were not included, and the Beaches at Risk study should also be consulted for completing a set of criteria.
In close consultation with the Department, a re•assessment of the beach selection criteria, covering social, economic, technical and environmental aspects was
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 6 Volume 1 • Main Report undertaken. These criteria were developed into a criteria matrix for assessing each project.
3.4 Prioritising Criteria In conjunction with DSE, a set of criteria has been prepared to rank the priorities and urgency of each beach nourishment project. The attributes considered in developing these criteria were those nominated in Attachment A of the Project Brief:
» strategic importance;
» functionality;
» utilisation;
» condition; and
» urgency. These criteria have been broadly based on asset protection, recreational and community use and supporting infrastructure. These criteria have also taken into account the objectives previously stated for the Enhancing Our Beaches program. A workshop with representatives from the Association of Bayside Municipalities and the Department was arranged early in the Study. This workshop was conducted over a half day at GHD’s Melbourne office on the 7th of November 2007 and consisted of 15 participants. The objective of this workshop was to further develop the social and economic assessment criteria of each nourishment site, drawing on the criteria developed by Reckon/ABM in 2001.
3.5 Visual Inspection Physical inspection of all beaches nominated in the previous studies, as well as other beaches identified as possible candidates for renourishment, was undertaken. These beaches include all sites that have received treatment since 2001 so that a brief status report of each of these sites could be prepared. A standard reporting sheet was prepared to ensure a consistent and comprehensive inspection of the important aspects of each site for later assessment. Photographs were taken of each site and have been provided to support the site inspection reports. The findings from the site inspections together with the original assessments in the Beaches at Risk study was used to re•assess each site in the current climate.
3.6 Prioritise the Nourishment Projects The nourishment projects were prioritised by generating a priority ranking developed by applying the agreed selection criteria and then combining the outcomes from the ABM/DSE workshop. The criteria matrix was used to drive this process and prioritising decisions were used to finalise the priority list.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 7 Volume 1 • Main Report 3.7 Determine Sand Demands and Quantities Sand for renourishment has traditionally come from the Port Phillip seabed by dredging, and for some projects this may continue to be the case. Preliminary schematic designs for the highest priority projects have been prepared so that sand quantity, quality and supporting infrastructure could be identified for cost estimate purposes. Where appropriate, climate change vulnerability was taken into account during preliminary design. In addition, the feasibility of conducting an investigative search for suitable offshore sources of sand has been considered. A preliminary assessment of sand retention measures has also been made for the highest priority sites, based on experience gained at successful nourishment sites recently completed around the Bay.
3.8 Asset Register Using standard Department asset fields, asset register entries have been prepared for each priority site. These include sand quantity, quality, probable source, design life, and estimated costs for short•term (5 – 10 years) and long•term (25 – 30 years) measures. The cost estimates are based on recent experience with nourishment projects around the Bay and were developed as high•level estimates for budget costing purposes.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 8 Volume 1 • Main Report 31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 9 Volume 1 • Main Report 4. Beach Assessment Criteria
4.1 General Prior to any inspections a set of beach selection criteria were developed from existing reports. This set of criteria provides the basis for selecting or rejecting beach sites for nourishment, within the forthcoming Enhancing Our Beaches funding program for beach nourishment projects around Port Phillip Bay. Approximately, the criteria are broken into two halves: the technical/functional criteria and the social and economic criteria. There are 7 technical criteria that focus on aspects of the beach that can be measured and observed during a site inspection and recorded against a benchmark or standard. The 6 social and economic criteria on the other hand, require a more detailed knowledge of the daily operations of the beach and are more qualitative. . Combing the criteria will provide a comprehensive tool to enable the analysis and understanding of the candidate beaches and eventually form the basis for nourishment prioritisation.
4.2 Technical Criteria The Beaches at Risk report provides some guidance as to the appropriate technical and functional criteria to be applied to each site for selection or rejection. Technical and functional criteria incorporate the physical beach condition as well as issues relating to public risk, public facilities, foreshore land and the protection of environmental values. These criteria are generally measurable or able to be determined without extensive investigation. Utilising the Beaches at Risk report, along with the assistance of DSE, the following 7 criteria have been established:
4.2.1 Beach Condition The following three criteria focus on the physics state of the beach and how it is changing:
» Percentage of the beach length that has been eroded;
» Percentage of the beach width that has been eroded; and
» Estimated rate of erosion, percentage of beach lost due to erosion since 2001 Beaches at Risk report.
4.2.2 Risk to Assets Criteria adopted for measuring risk to assets are:
» Public Risk: unstable cliffs pose a danger to the public, and this danger can be significantly reduced by nourishing;
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 10 Volume 1 • Main Report » Public Facilities: public facilities (retaining wall, paths, roadways, parks, buildings, drains, underground services) at risk of damage, and this risk can be significantly reduced by nourishing; and
» Foreshore Land: foreshore land is at risk of erosion and this can be reduced by renourishment.
4.2.3 Protecting Environmental Values This criteria is designed to ensure that the nourishment of the beach and associated works will not adversely impact on the environment, increased patronage as a consequence of nourishment will not adversely impact on the environment, nourishment would enhance the environmental value of the site, nourishment addresses or partially addresses the probable impact from climate change and the historic or cultural value will be enhanced by nourishment.
4.3 Draft Social and Economic Criteria The social and economic criteria are designed to incorporate and give emphasis to those aspects of the beach that are not specifically related to its physical appearance. These criteria are intended to incorporate the following areas of importance:
» Importance of the beach to the local and wider community;
» Levels of use and possible alternatives if the beach is unavailable;
» Adequacy of existing infrastructure to support beach visitors;
» Role of community and local Council in managing the beach;
» Impact the beach has on the local economy; and
» Other economic/tourism benefits that flow from the beach. The Association of Bayside Municipalities prepared a report in September 2001, Port Phillip – Coastal and Marine Planning Program – Social and Economic Criteria for the Assessment of Beach Renourishment Projects. This report provides criteria for the social and economic aspects but does not, by its own admission, address technical and functional criteria. Given the nature of the social and economic criteria, it is difficult to assess these criteria during a site investigation without extensive involvement, and is more suited to being assessed by those most familiar with each beach. Thus it was proposed that each of the Municipalities would provide input into the rating of these criteria. In order to ensure the criteria are adequate and understood, a workshop involving all relevant parties was convened to discuss and finalise the criteria.
4.4 Workshop On the 7th of November 2007 a workshop was held to discuss the progress of the beach nourishment project. Hosted by GHD and DSE, members of the various Bayside municipalities were invited to attend, comment on and assist in the development of the final social and economic criteria.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 11 Volume 1 • Main Report 4.5 Final Social and Economic Criteria Below is a list of the finalised social and economic criteria as well as typical indicators to assist in rating each beach. During the workshop the criteria from the September 2001, Port Phillip – Coastal and Marine Planning Program – Social and Economic Criteria for the Assessment of Beach Renourishment Projects report were refined to slightly to aid understanding and the clarity of input information that was to be received from the participating municipalities.
4.5.1 Social Value Importance of the beach to the local and wider community:
» This location is the main beach area for sub•regional (i.e. from local or immediately adjoining municipalities) and regional beach goers (i.e. from western suburbs areas or inner suburban/outer suburban areas);
» The area provides access and a hub for many ethnic and cultural groups; and
» The beach plays a significant role in the ongoing life of the local community.
4.5.2 Community Use Level of use and possible alternatives if the beach is unavailable:
» The condition of the beach is leading to overcrowding in peak summer months;
» The beach is attracting increasing numbers of beach goers and visitors each year;
» Access to the beach is compromised by the poor condition of the site;
» There are no alternative beaches or open space within close proximity; and
» The beach is considered safe for uses that are dependent on renourishment (eg swimming).
4.5.3 Supporting Infrastructure Adequacy of existing infrastructure to support beach visitors:
» Beach•related amenities (e.g. toilets, change rooms, shade, drinking water and signage) are sufficient and are well maintained;
» Parking facilities, roads and road management are adequate to support beach usage in the peak summer months;
» The beach area is supported by complementary social and recreational facilities;
» The beach is important as it links with other recreational systems (parks, paths, trails); and
» Good public transport is available to the beach area.
4.5.4 Community Management Role of community and local Council in managing the beach:
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 12 Volume 1 • Main Report » The foreshore area is well managed and maintained by the local Council/Committee of Management, including cleaning according to best practice guidelines;
» Council and local business, community and sorting groups are active in supporting the foreshore area and the renourishment project; and
» The Council/Committee of Management has adequate resources to maintain a renourished beach into the future.
4.5.5 Contribution to Local Economy Impact the beach has on the local economy:
» The presence of the beach is seen as a direct and significant contributor to the local economy;
» Many businesses rely on summer related beach activity to survive; and
» Revenue from and expenditure on beach precinct has important implications for overall revenue for the local Council/Committee of Management.
4.5.6 Scope for Economic Development Other economic/tourism benefits that flow from the beach:
» Ongoing business, residential and commercial developments directly relate to the popularity of the foreshore area; and
» Potential exists for creation or expansion of tourism services.
4.6 Final Agreed Criteria The final 13 criteria adopted for assessing the beaches are:
Technical Beach length Beach width Rate of erosion Public risk Public facilities Foreshore land Environmental value Social Social value Community use Supporting infrastructure Community management Economic Contribution to local economy Scope for economic development
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 13 Volume 1 • Main Report 4.7 Scoring The prioritisation of the beaches involves ranking them against the technical, social and economic criteria. For each of the 13 criteria, 7 technical and 6 social/economic, each beach has been scored depending on how applicable that criteria is to the specific beach. Once the beaches have been ranked against the criteria, each beach will go into a criteria matrix that has been prepared, see Appendix D. The matrix includes each of the selection criteria and how each beach ranks against them, and a subsequent total ranking and hence beach nourishment priority. A scoring arrangement has been included, which is expected to identify, initially, which beaches should be selected for further consideration and eventual prioritising. Each criterion requires a score of 1 to 5, with 5 being the highest rating (most in need of nourishment) as shown:
» 5 = complete agreement with criterion
» 4 = mostly agrees with criterion
» 3 = partially agrees with criterion
» 2 = in some way agrees with criterion
» 1 = no agreement or disagreement with criterion There are 13 criteria, with possible scores for a beach ranging from 5 to 65. Within this matrix, weighting the score for each criterion was considered, but has not been adopted. The criteria set seem to be evenly distributed across both technical and social criteria, hence giving equal balanced consideration, and thus avoiding the need for weighting.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 14 Volume 1 • Main Report 31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 15 Volume 1 • Main Report 5. Beach Assessment
5.1 Candidate Sites A list of beaches around Port Phillip Bay has been compiled from previous works and highlights those beaches around the Bay likely to be most in need or renourishment. The following is a list and a brief description of the 30 candidate sites in alphabetical order and Figure 1 illustrates their location around Port Phillip Bay:
Melway Beach Name and LGA Short Description Reference Altona – Hobsons Bay lengthy south•east facing beach 54, E12 Altona Coastal Park – heavily vegetated, poorly accessible 55, C9 Hobsons Bay south•east facing beach Blairgowrie – Mornington lengthy north•east facing beach 157, H12 Peninsula Brighton New St. – Bayside 1km long west facing beach 76, D3 Eastern Beach Geelong – short protected north facing beach 402, M3 Greater Geelong Elwood – Port Phillip 1km long south west facing beach 67, B5 Fishermans Beach – protected north•east facing beach 104, C12 Mornington Peninsula Half Moon Bay – Bayside short protected north•east facing 85, H2 beach Marina Cove – Mornington short, protected, poorly accessible 145, B2 Peninsula west facing beach McCrae Beach – Mornington lengthy north•west facing beach 159, B8 Peninsula Moorpanyal – Greater short protected south•east facing 442, E3 Geelong beach Mt Martha North – lengthy north•west facing beach 144, K10 Mornington Peninsula Mt Martha South • lengthy north•west facing beach 144, H12 Mornington Peninsula North Aspendale – Kingston lengthy south•west facing beach 92, F2 Parkdale – Kingston lengthy south•west facing beach 87, B10 Point Lonsdale – Borough of lengthy south•east facing beach 499, K4 Queenscliffe
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 16 Volume 1 • Main Report Melway Beach Name and LGA Short Description Reference Portarlington – Greater lengthy north facing beach 444, J6 Geelong Portsea – Mornington protected north•east facing beach 156, E2 Peninsula Queenscliff – Borough of lengthy east facing beach 499, H10 Queenscliffe Rippleside – Greater short, manmade, protected east 442, B10 Geelong facing beach Rosebud – Mornington short north•west facing beach 158, E11 Peninsula Rye – Mornington Peninsula lengthy north facing beach 168, G4 Shelleys Beach • Mornington poorly accessible north•east facing 156, H2 Peninsula beach Sorrento – Mornington lengthy north•east facing beach 157, C8 Peninsula St Helens – Greater short, manmade protected east facing 442, B9 Geelong beach St Leonards – Greater lengthy east facing beach 460, C10 Geelong Werribee South – Wyndham lengthy south•east facing beach 199, G11 West Rosebud – Mornington 1 km long north•west facing beach 169, J1 Peninsular Western Beach Geelong – short section of west facing cliff face 452, B2 Greater Geelong Williamstown – Hobsons short, protected south facing beach 56, A11 Bay
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 17 Volume 1 • Main Report Figure 1 Location of sites in Port Phillip Bay
5.2 Site Inspections The site inspections were carried out with the assistance of a standard site report sheet that encompassed the criteria outlined in Section 4. Appendix C shows a blank copy of the site inspection report sheet, while the completed report sheets for each of the sites can be found in Appendix D. The site reports were primarily focused to the gathering of information on the technical criteria while undertaking the inspection. Given each individual Municipality is likely to have a better understanding of the Social and Economic criteria relating to each beach, less emphasis has been put on gathering this information. However, relevant information visible during the inspection has been included on the report sheets. Before undertaking the 30 site inspections, the following preparation steps were undertaken:
» Became familiar with the 2001 Beaches At Risk report and the areas concentrated on in that report;
» Performed background investigation on the candidate beaches to become familiar with any previous studies/inspections.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 18 Volume 1 • Main Report » Prepared Melways maps to identify affected beaches;
» Identified the critical criteria to investigate; and
» Prepared a comprehensive site report sheet, as illustrated in Appendix C, to enable efficient, effective and consistent recording of critical information. At each site, the report sheets were filled out with all relevant criteria prompts commented on. Approximate measurements were taken where necessary. Photos of the beach and its relevant features were taken and are catalogued in Volume 2 of this Report to provide future reference and evidence for the site report. The detailed site reports, attached in Appendix D list the observations made during the site inspections for each site. The report encompasses each of the criteria including technical, social and economic, along with prompts and indicators to assist rating the criteria . A broad display of photographs have been included in Volume 2 for each of the selected beaches inspected. Volume 2 includes a Melways Map to illustrate the site location. Typically, the larger beaches with more features and those beaches displaying more symptoms of degradation have been more comprehensively catalogued.
5.3 Assessment by Bayside Municipalities Following the workshop, copies of the revised social and economic criteria were sent out to the Municipalities for them to provide comment and suggested scoring on each of their beaches. A DSE panel then reviewed these comments and indicative scores, and the final social and economic scores were concluded. The scores for each criteria have been totalled and the beaches ranked in order of priority, as shown in Table 1.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 19 Volume 1 • Main Report Table 1 Social and Economic Scoring and Comments Provided by DSE
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 20 Volume 1 • Main Report The assessment on the individual beaches made by the respective Municipalities provides first hand knowledge from a source that is most familiar with the particular beach and its operation. Having attended the workshop, representatives from each of the Municipalities have a greater understanding of the ranking process, and recognising that their submission would be reviewed and amended, if necessary, by DSE. This encouraged honest responses under each of the criteria rather than potentially rating each criteria 5 out of 5 without sufficient supporting evidence. Table 1 also illustrates the comments made by the DSE panel in response to the submissions made by each of the Municipalities. These indicate the level of consensus and any discrepancies.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 21 Volume 1 • Main Report 6. Assessment Results
6.1 Technical Assessment Table 2 shows the table of results for the technical criteria, while Table 3 illustrates the subsequent ranking of the beaches. As can be seen from the results, beaches that are more severely affected by erosion or those that pose a higher risk to the public and infrastructure, are ranked highest. Conversely those beaches that have not suffered adversely, or that have sustained their state from previous renourishment, are ranked lowest. All the beaches ranked in the top ten demonstrate significant areas of concern, whether it be based on one criterion or across multiple criteria. Altona for example, ranks highest because a significant portion of it length and width have been eroded away, in turn leading to other problems such as risk to public assets. Beach length and width are determined by estimating the average length and width of the current state of the beach and comparing it to the ideal or renourished state. In cases like Altona, Portarlington, St Helens and Rippleside, where 5 was score in one or both of these criteria, severe shortening and/or narrowing of the beach has occurred. Beaches such as Rosebud, Sorrento or Queenscliff, with scores of 1, have no signs of erosion and in some cases have accumulated sand. Rate of erosion is more difficult to estimate, given that it is compared to the status of the beach at the time of inspection for the 2001 Beaches at Risk report. A number of factors, such as the time of year the inspection is carried out and weather conditions, influence the likely state of the beach. However a thorough knowledge of the sand movement in Port Phillip Bay enables effective assessment on beach states and their likely erosion patterns. Beaches that pose a potential threat to the public have ranked highly in the public risk category. Marina Cove with its potentially unstable cliffs and the already sectioned off walkway along the cliff at Western Beach Geelong, each score 5. Flat and expansive beaches such as Queenscliff and Rosebud pose no threat to public risk and have a ranking of 1.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 22 Volume 1 • Main Report Technical/ Functional
Beach Value since 2001 Public Risk Beach width Beach length Environmental Rate of erosion Foreshore Land Public Facilities
Elwood Port Phillip 4 4 4 3 4 3 5 27 Brighton New St Bayside 3 3 3 2 4 3 3 21 Half Moon Bay Bayside 3 4 2 4 3 3 3 22 Parkdale Kingston 2 2 1 2 4 2 4 17 North Aspendale Kingston 4 4 3 3 3 4 4 25 Fishermans Beach Mornington Peninsula 2 3 2 3 3 3 3 19 Marina Cove Mornington Peninsula 3 3 2 5 3 2 2 20 Mt Martha North Mornington Peninsula 4 5 4 4 5 4 3 29 Mt Martha South Mornington Peninsula 2 2 2 3 3 2 2 16 McCrae Beach Mornington Peninsula 4 4 3 2 3 3 4 23 Rosebud Mornington Peninsula 1 2 2 1 1 2 1 10 West Rosebud Mornington Peninsula 1 3 2 1 1 3 3 14 Rye Mornington Peninsula 2 2 2 2 3 2 3 16 Blairgowrie Mornington Peninsula 3 4 1 3 4 2 4 21 Sorrento Mornington Peninsula 1 3 2 2 3 3 3 17 Shelleys Beach Mornington Peninsula 4 5 3 4 5 3 1 25 Portsea Mornington Peninsula 3 3 3 3 4 3 2 21 Point Lonsdale Borough of Queenscliffe 3 3 2 3 3 2 3 19 Queenscliff Borough of Queenscliffe 2 1 2 1 3 2 3 14 St Leonards Greater Geelong 3 4 3 2 3 3 4 22 Portarlington Greater Geelong 5 4 4 4 4 4 3 28 Eastern Beach Geelong Greater Geelong 3 3 3 2 3 3 5 22 Western Beach Geelong Greater Geelong 1 1 1 5 5 5 2 20 Rippleside Greater Geelong 4 5 2 3 4 3 3 24 St Helens Greater Geelong 5 4 2 4 4 3 3 25 Moorpanyal Greater Geelong 4 3 2 4 1 4 3 21 Werribee South Wyndham 3 4 3 2 4 4 3 23 Altona Hobsons Bay 5 5 5 3 4 3 5 30 Altona Coastal Park Hobsons Bay 3 2 2 1 2 4 2 16 Williamstown Hobsons Bay 2 2 1 2 4 2 3 16
Table 2 Technical Criteria Scoring
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 23 Volume 1 • Main Report Score Beach Ranking Municipality Total Technical Total
Altona Hobsons Bay 30 1 Mt Martha North Mornington Peninsula 29 2 Portarlington Greater Geelong 28 3 Elwood Port Phillip 27 4 North Aspendale Kingston 25 5 Shelleys Beach Mornington Peninsula 25 5 St Helens Greater Geelong 25 5 Rippleside Greater Geelong 24 8 McCrae Beach Mornington Peninsula 23 9 Werribee South Wyndham 23 9 Half Moon Bay Bayside 22 11 St Leonards Greater Geelong 22 11 Eastern Beach Geelong Greater Geelong 22 11 Brighton New St Bayside 21 14 Blairgowrie Mornington Peninsula 21 14 Portsea Mornington Peninsula 21 14 Moorpanyal Greater Geelong 21 14 Marina Cove Mornington Peninsula 20 18 Western Beach Geelong Greater Geelong 20 18 Fishermans Beach Mornington Peninsula 19 20 Point Lonsdale Borough of Queenscliffe 19 20 Parkdale Kingston 17 22 Sorrento Mornington Peninsula 17 22 Mt Martha South Mornington Peninsula 16 24 Rye Mornington Peninsula 16 24 Altona Coastal Park Hobsons Bay 16 24 Williamstown Hobsons Bay 16 24 West Rosebud Mornington Peninsula 14 28 Queenscliff Borough of Queenscliffe 14 28 Rosebud Mornington Peninsula 10 30 Table 3 Technical Ranking of the Beaches
6.2 Social and Economic Assessment The comments and scores provided under each of the social and economic criteria in Table 1 reflect both the importance of the beach within the Municipality and the level of concern about the state of the beach. Table 1 shows there are a number of beaches that have been acknowledged by the relevant Municipalities, and subsequently by the DSE, to have a low priority for beach nourishment at this point in time. No submissions were provided for these beaches, and consequently received a social and economic score of 0. As expected, the beaches that are deemed important in terms of social value and community use, that are well managed, that have sufficient supporting infrastructure
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 24 Volume 1 • Main Report and that contribute to the local economy and economic development, have scored highly. Altona and Elwood, ranked equal first, both perform very well in the social criteria and provide some economic benefits for the community. Both are large are extremely popular beaches that are well managed and have significant supporting infrastructure. Smaller, less accessible beaches such as Marina Cove and Shelleys Beach tend to perform poorly under the social and economic criteria. This is generally due to lack of size and access to the general public, and hence the limited investment and surrounding infrastructure to support the beach. Due to their restricted popularity they have little impact of the community economy. In this case, Marina Cove and Shelleys Beach happen to be surrounded by numerous larger and more accessible beaches that provide adequate alternatives for the public. With the input received from the Municipalities, and DSE having finalised each beach’s ranking under each of the criteria. Social and economic rankings can now be combined with the technical ranking to determine a final priority ranking list.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 25 Volume 1 • Main Report 7. Beach Priorities
7.1 General Once the technical, social and economic scores were calculated a total score was used to represent the relevant priority of each beach and its likelihood of receiving further investigation. We expect this task to identify a set of highest priority projects (up to four major projects with an expected design life of 25 to 30 years, and up to four minor projects with an expected design life of 5 to 10 years) as preferred candidates for detailed design and implementation.
7.2 Applying and Refining Social and Economic Assessment The social and economic assessment process was undertaken by parties with the greatest knowledge of the specific beaches so as to ensure the most definitive assessment was made. As discussed in Section 4, the criteria that were defined during the workshop were sent to the Municipalities representing each beach. These criteria were commented on and a representative score was given, with the results being sent to DSE. A specially selected DSE panel carried out a comprehensive review of the submissions, with the summary of the results shown in Table 1. The comments in the table reflect the view of the DSE panel on each of the submissions. The complete breakdown of the scores for each of the six social and environmental criteria is attached in Appendix D.
7.3 Final Priority List The final priority list is made up of a combination of the total scores from the technical criteria scores and the social and economic criteria. The total technical score, as assessed by GHD, is made up of 7 categories and has a potential score of between 5 and 35. The social and economic total, reviewed and finalised by the DSE panel, is made up of 6 categories and scores can range from 0 to 30 (0 represents non• submission by the relevant Municipality). Thus the total scores that determine each beach’s priority ranking, can range from 5 to 65. Table 4 shows some distinct groups when the technical and social/economic scores are totalled and the beaches are ranked in order of overall priority. The sites fall into five distinct score categories:
7.3.1 Greater than 50 These are the overall highest priority beaches (shown in red). As can be seen, both Altona and Elwood scored in the highest group for both technical and social/economic • with Altona scoring the highest ranking in both categories. Both beaches will be considered for nourishment and further design.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 26 Volume 1 • Main Report 7.3.2 45 to 50 The second tier beaches (shown in dark orange) are considered a good chance of being considered for nourishment works. These beaches generally scored well in both technical and social/economic categories, however may have lacked a little in a particular area.
7.3.3 40 to 45 These beaches will be considered if the beaches in the higher priority categories are deemed not feasible following further investigation or change in circumstances. These beaches usually score well in one of the two categories, or satisfactory in both.
7.3.4 20 to 40 These beaches (shown in yellow) will generally not to be considered for future investigation unless circumstances change. These beaches generally scored poorly in one or both of the technical and social/economic areas.
7.3.5 Under 20 The beaches (shown in blue) are not considered as candidates for further investigation. These beaches were not considered after submissions from Municipalities were not received, suggesting they are considered lower priority than comparative beaches.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 27 Volume 1 • Main Report Table 4 Summary of Final Beach Rankings
Beach Municipality Technical Social Total Ranking
Altona Hobsons Bay 30 24 54 1 Elwood Port Phillip 27 24 51 2 Mt Martha North Mornington Peninsula 29 17 46 3 Portarlington Greater Geelong 28 17 45 4 Half Moon Bay Bayside 22 21 43 5 North Aspendale Kingston 25 18 43 5 Eastern Beach Geelong Greater Geelong 22 21 43 5 Portsea Mornington Peninsula 21 22 43 5 Brighton New St Bayside 21 21 42 9 McCrae Beach Mornington Peninsula 23 18 41 10 St Helens Greater Geelong 25 16 41 10 Werribee South Wyndham 23 18 41 10 Blairgowrie Mornington Peninsula 21 19 40 13 Point Lonsdale Borough of Queenscliffe 19 21 40 13 St Leonards Greater Geelong 22 18 40 13 Western Beach Geelong Greater Geelong 20 20 40 13 Rippleside Greater Geelong 24 16 40 13 Shelleys Beach Mornington Peninsula 25 11 36 18 Moorpanyal Greater Geelong 21 15 36 18 Fishermans Beach Mornington Peninsula 19 16 35 20 Queenscliff Borough of Queenscliffe 14 20 34 21 Marina Cove Mornington Peninsula 20 7 27 22 Parkdale Kingston 17 0 17 23 Sorrento Mornington Peninsula 17 0 17 23 Mt Martha South Mornington Peninsula 16 0 16 25 Rye Mornington Peninsula 16 0 16 25 Altona Coastal Park Hobsons Bay 16 0 16 25 Williamstown Hobsons Bay 16 0 16 25 West Rosebud Mornington Peninsula 14 0 14 29 Rosebud Mornington Peninsula 10 0 10 30 The seven highest priority beaches, as shown in Table 4, are discussed further in detail in Section 10. A preliminary investigation and concept design have been undertaken to determine the feasibility of potential nourishment projects.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 28 Volume 1 • Main Report 31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 29 Volume 1 • Main Report 8. Sand Sourcing Analysis
8.1 General Sand for renourishment has historically come from the Port Phillip seabed by dredging, and for some projects this may continue to be the case. At the present time, an offshore sand source is being used to nourish Sandringham Beach at Royal Avenue by dredging. Recent experience at Beacon Cove and Brighton (Middle Brighton Pier/Shared Pathway), however, demonstrates that, for the very northern end of the Bay, sand needs to be supplied from on•shore sources due to a lack of reliable offshore borrow sites. There is a possibility that the Port of Melbourne Corporation’s Channel Deepening Project may be able to supply suitable sand at the southern end of the Bay, and this opportunity for sand supply is discussed below. In considering the demands for sand from viable sources, a general principal applies, where sand grain size normally needs to be the same size or coarser than the native beach sand grain size. If finer sand is used, groyne structures or other means of anchoring the sand is usually needed, and a larger volume of sand is normally provided to allow for some losses over time. All sand sources also need to be tested to establish any presence of contamination, which would prevent the sand from being used for nourishment. The feasibility of conducting an investigative search for suitable offshore sources of sand is also discussed below. A preliminary assessment of sand sizes, quantities and retention measures has been made (in Section 10) for the highest priority sites, based on experience gained at successful nourishment sites recently completed around the Bay.
8.2 Beaches at Risk Study This study made extensive use of a bay•wide seabed sediments survey conducted by Beasley in 1966, and other surveys undertaken between 1970 and 1990. The general conclusions drawn were:
» Sand which has accumulated in the southern end of the bay, typically in and around the South Channel area, is medium to fine grained sand, which would be suitable for nourishing beaches in the southern part of the Bay, including beaches in Corio Bay;
» In the northern part of the Bay (typically north of Frankston on the east side and north of Little River on the west side), there are intermittent deposits of coarse sand suitable for beach nourishment of the northern beaches. These deposits need to be more specifically identified by investigations to confirm their location and extent; and
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 30 Volume 1 • Main Report » A brief discussion of land•sourced sand for nourishment was provided – the conclusion drawn was that suitable sand was rare and costs of transporting are high. This study also assessed the dredging methods needed to win sand from offshore sources and concluded that a two•stage dredging process would be needed in most cases. This involves a trailer suction hopper dredge to excavate material from the source and place it in a re•handling area offshore from and close to the beach being renourished. Then utilising a cutter suction dredge this sand would be recovered from the re•handling area, pumping to shore to nourish the beach. However, this dredging technique is unlikely to be cost•effective, due to the high mobilisation costs associated with two dredges. The availability of dredging plant locally was the primary factor controlling the cost of obtaining sand from the Port Phillip Bay seabed. This study also briefly discussed the expectation of dredging the shipping channels and possibly using this project as a source of suitable sand. No firm conclusions were drawn from this discussion. In more recent years, suitable trailer suction hopper dredges have become less available, with no dredges of this type currently based in Victoria. It is understood the closest Australian•based trailer suction hopper dredge operates on the Queensland Gold Coast. A similar dredge operates in New Zealand and can be available to work in Australia. A number of cutter suction dredges operate in Port Phillip Bay, based in Queenscliff.
8.3 Channel Deepening as a Source of Nourishment Sand There is a possibility that the Channel Deepening Project may be able to supply suitable sand at the southern end of the Bay. The feasibility of this source has been examined here, based on information contained in the Environmental Effects Statement (EES) and the Supplementary EES for the Channel Deepening Project.
8.3.1 Port Phillip Bay Beach Design Project In 2002, DSE conducted the Port Phillip Bay Beach Design Project, which included investigation of the viability of utilising dredge spoil as a low•cost option for beach fill at eight high•priority sites around the Bay. A detailed report on this Project was provided to the Coasts & Ports Australasia Conference in 2003, by Zoe Toogood (DSE), Peter Riedel (Coastal Engineering Solutions) and Gerry Byrne (Vantree). With the expectation that the Channel Deepening Project may be implemented in the then foreseeable future, DSE was keen to assess the potential for utilising suitable spoil from this project, as well as from regular maintenance dredging programmes undertaken by the then Victorian Channels Authority (since amalgamated into the Port of Melbourne Corporation) and Parks Victoria, for beach nourishment projects around the Bay. There was, at this time, a clear expectation that the Channel Deepening Project would generate in the order of 30 million cubic metres of spoil, a significant proportion of which was expected to be fine to medium sand from the South Channel.
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 31 Volume 1 • Main Report The current estimate of quantities of sand to be dredged from the South Channel as part of the Channel Deepening Project is 14.6 million cubic metres (in•situ volume). All of this material has been classified as uncontaminated sand.
Toogood, Riedel and Byrne concluded that, while opportunities exist to re•use South Channel dredge spoil as fill for beach nourishment projects in Port Phillip Bay, it will not always be a viable option. Factors working against viability include:
» Differences between the physical characteristics of the dredged spoil and the native beach sediments (grain size, colour, shell content, etc.);
» Excessive cost due to excessive steaming distances between the point of spoil generation and final destination;
» Offshore bathymetry will restrict access to within reasonable onshore pumping distances at some sites; and
» The costs of land•based sources of sand may be competitive for some sites. The conclusions were:
» South Channel dredge spoil would be a cost•effective option for nourishment of several beaches in the Geelong area, including Eastern Beach, St Helens and Rippleside;
» South Channel dredge spoil could also be used to nourish Altona Beach, where it would be a comparatively expensive source of beach fill, but may become more attractive if cheaper alternatives are discarded on social or environmental grounds; and
» South Channel dredge spoil would not be considered to be a viable source of fill for nourishment of Moorpanyal, Mentone, Brighton or Elwood beaches, primarily due to the need for sand coarser than available from the South Channel. Comparatively high cost was also a contributing factor to reaching this conclusion.
8.3.2 Channel Deepening Environment Effects Statement In 2004, the Port of Melbourne Corporation released for Panel Hearing purposes the Channel Deepening Project (EES), prepared by Parsons Brinckerhoff. This document assessed the alternatives available for the use of dredged material. In considering the volume of uncontaminated sand to be dredged from the South Channel, a total of seven alternative uses were identified and assessed. These were:
» Beach renourishment/coastal protection;
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 32 Volume 1 • Main Report » Creation of environmental island for avifauna habitat/storm haven;
» Extension of near shore habitat;
» Creation of marine habitat in or around Capel Sound;
» Island off St Kilda;
» Use by industry; and
» Use as commercial garden soil. While significant social benefits were identified for the use of sand for beach renourishment, the EES concluded that technical and economic disbenefits outweighed the benefits. The assessment stated that: “It is evident that beach renourishment could utilise only a small proportion (0.5 million m3) of the total quantity of dredged material (32.1 million m3) that would be generated by the Project. It is also likely to be a relatively expensive operation, given the need to either double•handle (via placement at temporary sites) the material or use additional equipment to transport it. The reuse of dredged material for the renourishment of individual beaches around the Bay has not been recommended for further consideration, because work undertaken to date (both prior to, and as part of this EES) has shown that the sand from the project is not compatible for a number of the beaches that require renourishment. Where the sand is compatible, other work undertaken has identified other sand sources that are closer or more cost•effective than those available from the Project. However, given the importance of beach renourishment to bayside residents and other beach users, PoMC will continue to work with the Victorian Government agencies and local Councils to investigate future beach renourishment around the Bay. It is not recommended at this stage. “ The Supplementary EES for this project, completed in 2007, includes a more detailed evaluation of dredged material management options (refer SEES, Appendix 23, Golder Associates, Jan, 2007). This report concludes that: The recommended use for Type II material [2.1 million m3 of uncontaminated coarse to fine sand] is in construction of a constraining cap for one of the DMGs. Beach renourishment would be a viable option if a proponent identifies a project of sufficient size. All Type II material will be used for within•project beneficial use (PMDMG cap). This means that the “best” sand from the South Channel will all be allocated to capping the Port Melbourne Dredge Material Ground, which is the target DMG to receive
31/21982/146043 Review of Beach Nourishment Priorities for Port Phillip Bay 33 Volume 1 • Main Report
contaminated sediments dredged from the Yarra River, and will not be available for beach nourishment. Type III material (13 million m3 of uncontaminated fine sand to silty/clayey sand) is unlikely to be suitable for beach nourishment because of poor proximity to target beaches, poor match of grain size and incompatible project timing. Consequently, most of this material is proposed to be disposed into the southern Dredged Material Ground off Mt Martha. A primary constraint to utilising dredged spoil from the Channel Deepening Project is the project’s timing for approval and start. The current status of this Project is understood to have all approvals in place, and dredging has commenced on schedule in February 2008. Dredging of the South Channel is scheduled to commence in March 2008 and continue for three months. In the foreseeable future, the Channel Deepening Project is not considered to be a viable source of beach nourishment sand because: