Agenda of Southern Floodplain Risk Management Committee

Shoalhaven City Council

Southern Floodplain Risk Management Committee

Meeting Date: Wednesday, 25 November, 2020 Location: Teams Time: 4.00pm

Please note: Council’s Code of Meeting Practice permits the electronic recording and broadcast of the proceedings of meetings of the Council which are open to the public. Your attendance at this meeting is taken as consent to the possibility that your image and/or voice may be recorded and broadcast to the public.

Agenda

1. Apologies 2. Confirmation of Minutes Nil 3. Declarations of Interest 4. Presentations SFM20.1 Terms of Reference SFM20.2 Overview of NSW Floodplain Development Manual and Purpose of Floodplain Risk Management Committees John Murtagh, Senior Natural Resource Officer, Biodiversity and Conservation, Department of Planning, Industry and Environment

5. Reports SFM20.3 Floodplain Management Program and Projects Update ...... 1 SFM20.4 Lower Shoalhaven River Floodplain Risk Management Study and Plan Update ...... 6 SFM20.5 St Georges Basin Floodplain Risk Management Study and Plan Update ...... 9 SFM20.6 Currarong Creek Flood Study Update ...... 12 SFM20.7 Millards Creek Flood Study Update ...... 14 6. General Business

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Membership Clr White – Chairperson All Councillors Chief Executive Officer (or nominee)

Community representatives:- Michael Brungs Adam Crossley Holly Gunton Paul Mitchell David Laidlaw

Government Agency representatives:- Local Aboriginal Land Council NSW State Emergency Services Department of Planning, Environment and Industry (DPIE) Other relevant Government Agency representatives

Quorum – 3 (provided that a minimum of the Chairperson & two Community Representatives are present)

Purpose: The principal objective of the Southern Floodplain Risk Management Committee is to assist Shoalhaven City Council in the development and implementation of one or more floodplain risk management plans for the southern area of the Council. This will need to be in accordance with the NSW Floodplain Development Manual. The southern area applies to the following catchments: • Lake Conjola; • Narrawallee; • Mollymook; • Ulladulla; • Burrill Lake; • Lake Tabourie; and • Willinga Lake Role: 1. To assist the Council in the development and implementation of the floodplain management plan for the areas listed under ‘Purpose’ (see above); 2. To assist the Council monitoring and assessing the effectiveness of the management plans during and after its implementation; and 3. To assist the Council providing input into known flood behaviour as part of the flood study.

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SFM20.3 Floodplain Management Program and Projects Update

HPERM Ref: D20/519218

Section: Environmental Services Approver: Phil Costello, Director - City Development

Reason for Report To inform the Committee of the current Floodplain Management Program and other projects undertaken by Council’s flood unit.

Recommendation (Item to be determined under delegated authority)

That the Committee receive the Floodplain Management Program and Projects report for information.

Options 1. The Committee receive the report for information. Implications: Nil SFM20.3

2. The Committee could choose an alternate recommendation. Implications: Nil

Background Floodplain Management Program Council receives grant funding from Department of Planning, Industry and Environment (DPIE) to undertake projects under their Floodplain Management Program. Grant funding is provided to Council on a 2:1 basis, with grant applications sought each financial year. The Floodplain Management Program provides grant funding to: • Develop flood studies; • Develop floodplain risk management studies and plans (FRMSP); and • Implement flood mitigation options identified in floodplain risk management plans. Council is currently undertaking the following projects from the program: • Review of the Lower Shoalhaven River Floodplain Risk Management Study and Plan; • Review of the St Georges Basin Floodplain Risk Management Study and Plan; • Millards Creek Flood Study; • Currarong Creek Flood Study. Please refer separate business papers for more detail in relation to the above projects.

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Council is seeking grant funding for the review of the Broughton Creek Flood Study. Council is currently awaiting advice from DPIE in relation to whether Council has been successful or not. Furthermore, a capital budget bid has been submitted for 2021/22 financial year to fund this project if Council were not successful with grant funding.

Shoalhaven Flood Alert Network Council maintains a network of water level and rain gauges that are part owned by Council and the Bureau of Meteorology (BoM). There are 21 water level gauges and 46 rain gauges throughout the LGA. In the Shoalhaven River catchment alone, there are 12 water level gauges and 17 rain gauges. The gauges feed into BoM’s flood alert network, providing Council access to live data recordings through the Enviromon software. The benefit of having this secondary Enviromon software and data recording is that it provides back up to BoM’s system, allows information to be interrogated, and allows email alerts which are triggered by certain water levels or

rainfall amounts to be set.

The service level agreement between the Natural Resources and Floodplain Unit and the Communications Section of Shoalhaven Water is currently being updated to ensure the system continues to be maintained and function at its highest level. In addition to gauges, water level boards are present at gauge sites so that visual checks of the water level can occur. This is most beneficial during a flood event, when the gauges are most likely to fail due to debris, dynamic changes in rainfall and water level, gauges being damaged due to extreme weather. SFM20.3 In many locations Manly Hydraulics Laboratory (MHL) has gauges alongside or joining Council’s gauges. The benefit of having two gauges in the one location is that information can be validated should one system fail. It also allows cost savings and knowledge sharing for sites with joint infrastructure. In the coming year Council will be implementing recommendations of adopted FRMSP and working with local State Emergency Service (SES) Units to identify locations for the installation of additional gauges and water level boards. A water level gauge is being procured for a site in Woollamia, and Council is further investigating an additional rainfall gauge upstream of Fisherman’s Paradise. Tomerong water level gauge was destroyed in the August 2015 flood. This gauge provides vital information to the SES, aiding them in their flood planning and response during a flood event. Council has received funding from the Natural Disaster Relief and Recovery Arrangements (NDRRA) and the gauge has been replaced. A capital budget bid has been submitted for 2021/22 financial year to fund a rainfall gauge to be installed in the upper reaches of the Lake Conjola catchment.

SMART Management Water Project The Illawarra Shoalhaven Joint Organisation (ISJO) Councils have formed an unprecedented partnership with the University of Wollongong (UOW) and corporate property group Lend Lease, to break new ground in the field of innovative water management. Water management is an area of key community concern and is identified in the Smart Region Strategy as an area warranting early investment in smart technologies. The SMART Management Water project will use new smart technologies and develop data analytics to help improve water quality, flood mitigation and ensure community safety in flash flood events. The project will be delivered through five components:

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1. Stop Block: Improved stormwater culvert blockage management and analytics including new rugged sensors 2. Flood Aware: A new information platform for the public to provide warnings and other information to reduce risk to life and property 3. Go Flow: New estuary management solutions including sensors and cameras to reduce flooding 4. Quality Watch: New water quality monitoring stations including custom technology, sensors and a regional Internet of Things network at Lend Lease’s Calderwood development 5. Pollution Stop: Improved water quality with new sensing devices and analytics in monitoring stations including changes to management of gross pollution traps

Shoalhaven City Council Natural Resources and Floodplain Unit have been working with project partners in the “Go Flow” component of this project. The aim is to: 1. Improve transparency regarding Councils’ decisions to mechanically open an estuary

(using Council plant to breach the existing sand berm) prior to a significant rainfall

event. 2. Reduce flood-risk for residents and businesses upstream of the ICOLLS entrance. 3. Reduced costs to Councils – the smart technology solutions will automatically advise Councils if ambient conditions are conducive to mechanically breaching the sand berm. This replaces the periodic site observations that currently need to be made by Council officers to assess berm breach conditions.

4. Improved information for Council officers to assist in refining the berm breach policy SFM20.3 over time and to better understand the trade-offs between reduced flood risk and any ecological and/or recreational impacts that may be created through compliance with existing ICOLLS management policy. Following deployment of related SMART cities projects including distributed rainfall and water level sensors, an evaluation of sensor positioning and reliability will be conducted to determine whether local rainfall / water level sensing data can be used preferentially to predicted data, particularly to identify when emergency breach is required. This project is considered to be in the pilot phase and will require further research from academia. The current methods of management will need to continue until such time these systems are robust and can be relied on.

Management of Flood Mitigation Assets In the early 1970s a system of Flood Mitigation Drains, Levee Banks, Flood Gates and Bridges was constructed on the Shoalhaven River floodplain to assist in the control of floodwaters and tidal inundation of the surrounding land. The agriculture drainage system consisted of 50 channels with a total length of 48.5 km within the Shoalhaven floodplain in the localities of Worrigee Swamp, Jorams Creek, Bolong, Numbaa, Berry/Far Meadow, Brundee, Pyree, Coomonderry/Coolangatta, Saltwater Creek and Nowra. In addition, Council maintains 23 km of flood levee assets within the Lower Shoalhaven Floodplain. A full list of assets can be found in the asset management plan: https://doc.shoalhaven.nsw.gov.au/displaydoc.aspx?record=POL12/63 Council is committed to maintaining the flood mitigation system to a high standard and in a manner that protects the community, the environment, assets and productive agricultural land from inundation; this in partnership with landowners and relevant State Government Agencies. The routine maintenance of the flood mitigation structures includes: 1. The regular inspection of levees and drains, including post flood event;

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2. Removal and/or treatment of noxious and aquatic weeds in drains; 3. Sediment removal to maintain design levels in the drains; 4. Removal of emergent, aquatic and terrestrial vegetation to maintain appropriate flow and operation of the drains; 5. Levee bank repairs as required. Council is committed to providing adequate agriculture drainage channels to help assist in the establishment and longevity of pastoral land and help manage water inundation in this area. To achieve this, efficient channel maintenance is essential. The build-up of aquatic and emergent plants in the agriculture drainage channels reduces their efficacy to remove water during flood periods and during periods of high rainfall. The objective of the proposed activity is to undertake routine maintenance of the agriculture channels by 1. Clearing and removing weeds and other vegetation that may adversely affect the

operation of the system. 2. Excavation of sediment in drains to maintain the design levels and to mitigate the risk of property damage and significant pasture inundation. Council in partnership with New South Wales Public Works have undertaken a visual levee audit of the Terara levee and identified repairs post floods of July and August 2020. A number of other defects along the remaining levee system have also been identified. Council has lodged application for funding under the Natural Disaster Relief and Recovery SFM20.3 Arrangements to undertake these repairs. Furthermore, a capital budget bid has been submitted for 2021/22 financial year to fund pre- existing repairs identified in the visual audit recently undertaken. The audit identified $220,000 worth of repairs required to maintain the integrity (and increase longevity) of the levee assets.

Shoalhaven River Flood Levee Rehabilitation Project Council conducted a levee audit post August 2015 flood event. The audit identified sections of the levee damages that were categorised as being in urgent need of repair. Following the audit, Shoalhaven experienced flood in June 2016, during which further damage occurred. The levee repair work was partially funded by the NDRRA. Once work was underway at Comerong Island more damage was discovered and Shoalhaven City Council provided an additional $500,000 which brought the total project cost approximately $2.4 million. Council has now received 75% of the above claims with the outstanding amount currently being processed by the Office of Emergency Management.

Development Applications, Planning Proposals and Council Projects Council’s flood engineers provide professional advice on the range of development applications in flood prone land, planning proposals in flood prone land (including water quality) and Council projects located within flood prone land. Within the 2020/21 financial year, Council’s flood engineers have completed over 150 development and caravan park application referrals, ranging from minor developments to major developments such as the Ulladulla Bunnings Project. Some of the current planning proposals that flood engineers are involved in as follows, both from flooding and water quality aspect: • Moss Vale North Urban Release Area;

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• Nowra Riverfront Precinct; • South Nowra Industrial Lands; • Sealark Road Callala Bay; • Conjola Park Master Plan; • Mundamia Urban Release Area;

Some of the Council projects flood engineers have been involved in: • Far North Collector Road Project (FNCR); • East Nowra Sub Arterial Road (ENSA); • Bongaree (Berry District Park); • Development Control Plan for Hitchcocks Lane, Berry; • Thurgate Oval – Proposed Dog Park; • Lady Denman Reserve Plan of Management; • Playground Concept Kangaroo Valley; • Paringa Park Proposal.

A capital budget bid has been submitted for 2021/22 financial year to a floodplain risk study for the Nowra Riverfront Precinct project. The proposed study will identify strategic flood related controls for future development of this precinct. Council needs to ensure flooding is considered in this proposal.

Flood Certificates SFM20.3 Shoalhaven City Council issues flood certificates in 12 catchments within the local government area (LGA). Council on average issues several hundred flood certificates per annum to the public. Flood certificates show summarised information about flooding for individual properties, most often based on the computer calculations and mapping carried out by Council. Information to assist in preparing Development Applications is given on the Certificates where available. Council recently embarked on a project to automate this process. This 2-phase project will ultimately allow applicants to directly download this information instead of the typical 10-day turnaround to produce a certificate. Council staff have completed the first phase of automating this process and is now working towards achieving a fully automated process. However, fully automating the process will take some time because Council needs to ensure that automated flood information produced is accurate.

Community Engagement Community engagement is a core part of all work conducted by the Floodplain Unit. Without support from the Floodplain Management Committees, State Government agencies and community members the work we complete would not be possible. Ongoing engagement ensures work is understood and supported.

Risk Implications Ensuring these projects are conducted allows Council to conduct floodplain management in a manner which reduces risk to individuals, the community and infrastructure within the floodplain.

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SFM20.4 Lower Shoalhaven River Floodplain Risk Management Study and Plan Update

HPERM Ref: D20/519473

Section: Environmental Services Approver: Phil Costello, Director - City Development

Reason for Report To provide Council and the recently formed Floodplain Risk Management Committee with an update of the review of the Floodplain Risk Management Study and Plan (FRMS&P) for the Lower Shoalhaven River catchment.

Recommendation (Item to be determined under delegated authority) That the Committee receive the Floodplain Risk Management Study and Plan report for information.

Options 1. The Committee receive the report for information. SFM20.4 Implications: Nil.

2. The Committee could choose to provide an alternative recommendation for future consideration by Council. Implications: This option could delay the progress of the project, result in additional project costs and/or prevent the completion of a Flood Study within the project timeframe.

Background The study area comprises the Lower Shoalhaven River floodplain from Burrier to the primary entrance to the Tasman Sea at Crookhaven Heads and the intermittently open and closed entrance at Shoalhaven Heads. The objective of this study is to improve understanding of flood behaviour and impacts, and better inform management of flood risk in the study area in consideration of the available information. The study will also provide a sound technical basis for any further studies. The previous Floodplain Risk Management Study and Plan (FRMS&P) for the Lower Shoalhaven River was completed in 2011. A review was recommended as per the NSW Floodplain Development Manual. It is noted that the Australian Rainfall and Runoff (ARR) Guidelines were updated in 2019 and this resulted in a number of changes to input parameters for design event flood modelling such as Bureau of Meteorology (BoM) design rainfall depths and ARR rainfall losses and design temporal patterns. The study outputs will inform decision making for investing in the floodplain, managing flood risk through prevention, preparedness, response and recovery activities, and informing and educating the community on flood risk and response to floods.

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Funding was approved by DPIE for this study in October 2017 and Cardno were engaged to prepare the Lower Shoalhaven River FRMS&P in June 2018.

Shoalhaven River.

The design event modelling is underway. The design event peak flows from the hydrological modelling are being compared against Flood Frequency Analysis (FFA) of historic gauging records prior to completing and mapping of flood results from the design event modelling. The design event flood modelling will be completed for the full range of design flood events from 20% Annual Exceedance Probability (AEP) to the Probable Maximum Flood (PMF). The outcomes from the hydrological and hydraulic modelling will be peer reviewed by an industry expert following the completion of the design event modelling. SFM20.4 The current project completion date is 31 May 2021. The complex nature of the Shoalhaven River catchment has resulted in some programme delays associated with completing the model calibration and ensuring the design event flows from the hydrological model agree with peak flow estimates from the FFA. Further to this the consultants progress on this project has been unsatisfactory at times and this resulted in Council issuing two non- conformance letters. Based on these project delays over the last couple of years, Council and DPIE do not believe that a FRMS&P can be completed within the project timeline. Therefore it is proposed to complete a Flood Study in the current funding term. A minor extension in project programme is being investigated. Council expects that all the Flood Study tasks can be delivered by the consultant within this timeline. This will result in the development of updated hydrological and hydraulic models, mapping of revised flood outputs across the entire Lower Shoalhaven River floodplain and modelling of a number of other scenarios such as levee failure and overtopping, dam break assessment and climate change assessment to better understand flooding behaviour in these scenarios. A small number of tasks that would normally form part of a FRMS&P will be completed as part of the current Flood Study. However, a number of tasks that would normally be completed as part of a FRMS&P will not be completed. Tasks that will not be completed as part of the current Flood Study include a review of the current entrance management policy and the identification and assessment of potential flood mitigation options. A FRMS&P for the Lower Shoalhaven River floodplain will be undertaken in the future following the completion of the Coastal Management Plan (CMP).

Southern Floodplain Risk Management Committee – Wednesday 25 November 2020 Page 8 information about the study and gather information. The website will be updated during the duration of the project to provide relevant information at each stage of the study. An information newsletter was also prepared for the digital and physical distribution to the residents within the catchment. The newsletter informed residents about the study and how to complete the survey either online or submit their responses on a hard copy questionnaire. The brochure provided an outline of the floodplain risk management process and the objectives of the study. Council opted to publish this information through targeting advertising and community forums. A total of 61 responses were recorded from the online consultation. Project updates were previously provided to the Shoalhaven Natural Resources and Floodplain Management Committee. Now that Floodplain Risk Management Committees have been formed, updates will continue to be reported to and discussed with members of this committee. Following the completion of the Draft Lower Shoalhaven River Flood Study, community consultation will be undertaken through both a presentation to the Floodplain Risk

Management Committee and a public exhibition period in 2021.

Financial Implications The Lower Shoalhaven River FRMS&P is 2/3 funded by DPIE and 1/3 funded by Council. This funding has been approved under the NSW State Government ‘Floodplain Management Program’ on a 2:1 basis. Council’s matching 1/3 contribution comes from the existing general Floodplain Management Program SFM20.4 budget. There have been no increases in project cost beyond the original approved funding.

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SFM20.5 St Georges Basin Floodplain Risk Management Study and Plan Update

HPERM Ref: D20/519486

Section: Environmental Services Approver: Phil Costello, Director - City Development

Recommendation (Item to be determined under delegated authority) That the Committee receive the St Georges Basin Floodplain Risk Management Study and Plan report for information.

Options 1. The Committee receive the report for information. SFM20.5 Implications: Nil.

Background The study area comprises St Georges Basin itself, the Estuary area, Sussex Inlet and upstream residential areas along the tributary creeks. The entire catchment covers an area of approximately 358 square kilometres with approximately 10% of the catchment area covered by the Basin itself. The catchment area of the Basin contains a number of creeks including Pats Creek, Home Creek, Wandandian Creek, Tomerong/Cockrow Creek, Cow Creek, Tullarwalla Creek and Warrowing Creek. The Basin connects to the ocean through the Sussex Inlet Channel and there are no recorded periods of closure of the Basin’s entrance. The objective of this study is to improve understanding of flood behaviour and impacts, and better inform management of flood risk in the study area in consideration of the available information. The study will also provide a sound technical basis for any further studies. The previous Floodplain Risk Management Study and Plan (FRMS&P) for the St Georges Basin was completed in 2013. A review was recommended as per the NSW Floodplain Development Manual. It is noted that the Australian Rainfall and Runoff (ARR) Guidelines were updated in 2019 and this resulted in a number of changes to input parameters for design event flood modelling such as Bureau of Meteorology (BoM) design rainfall depths and ARR rainfall losses and design temporal patterns.

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The study outputs will inform decision making for investing in the floodplain, managing flood risk through prevention, preparedness, response and recovery activities, and informing and educating the community on flood risk and response to floods. Funding was approved by DPIE for this study in October 2017 and Cardno were engaged to prepare the St Georges Basin FRMS&P in June 2018.

Current Status of the Project The data collection, model development and calibration phases of the investigation have been completed. The hydrological and hydraulic models have been calibrated against a number of historic flood events and found to provide a reasonable overall calibration. The design event modelling is underway and will be completed for the full range of design flood events from 20% Annual Exceedance Probability (AEP) to the Probable Maximum Flood (PMF). The outcomes from the hydrological and hydraulic modelling will be peer reviewed by an industry expert following the completion of the design event modelling. The current project completion date is 31 May 2021. The complex nature of the St Georges Basin catchment has resulted in some programme delays associated with completing the model calibration however achieving a robust model calibration was critical to ensure confidence in the model results. Further to this the consultant’s progress on this project has been unsatisfactory at times and this resulted in Council issuing two non-conformance letters. SFM20.5 Based on these project delays over the last couple of years, Council and DPIE do not believe that a FRMS&P can be completed within the project timeline. A minor extension in project programme is being investigated. Therefore Council has proposed to complete a Flood Study in the current funding term. Council expects that all the Flood Study tasks can be delivered by the consultant within this timeline. This will result in the development of updated hydrological and hydraulic models, mapping of revised flood outputs across the entire St Georges Basin floodplain and modelling of a number of other scenarios such as a climate change assessment to better understand flooding behaviour in various scenarios. A small number of tasks that would normally form part of a FRMS&P will be completed as part of the current Flood Study. However, a number of tasks that would normally be completed as part of a FRMS&P will not be completed. Tasks that will not be completed as part of the current Flood Study include the identification and assessment of potential flood mitigation options.

Community Engagement The first round of community consultation was undertaken between November 2018 and February 2019. A project website was published by Council to inform the community about this project. The website has been developed to provide the community with detailed information about the study and gather information. The website will be updated during the duration of the project to provide relevant information at each stage of the study. An information newsletter was also prepared for the digital and physical distribution to the residents within the catchment. The newsletter informed residents about the study and how to complete the survey either online or submit their responses on a hard copy questionnaire. The brochure provided an outline of the floodplain risk management process and the objectives of the study. Council opted to publish this information through targeting advertising and community forums. A total of 55 responses were recorded from the online consultation.

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Project updates were previously provided to the Shoalhaven Natural Resources and Floodplain Management Committee. Now that Floodplain Risk Management Committees have been formed, updates will continue to be reported to and discussed with members of this committee. Following the completion of the Draft St Georges Basin Flood Study, community consultation will be undertaken through both a presentation to the Floodplain Risk Management Committee and a public exhibition period in 2021.

Financial Implications The St Georges Basin FRMS&P is 2/3 funded by DPIE and 1/3 funded by Council. This funding has been approved under the NSW State Government ‘Floodplain Management Program’ on a 2:1 basis. Council’s matching 1/3 contribution comes from the existing general Floodplain Management Program budget. There have been no increases in project cost beyond the original approved funding.

SFM20.5

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SFM20.6 Currarong Creek Flood Study Update

HPERM Ref: D20/519499

Section: Environmental Services Approver: Phil Costello, Director - City Development

Reason for Report To provide the recently formed Floodplain Risk Management Committee with an update of the Flood Study for Currarong Creek.

Recommendation (Item to be determined under delegated authority)

That the Committee receive the Currarong Creek Flood Study report for information.

Options 1. The Committee receive the report for information. Implications: Nil.

SFM20.6 2. The Committee could choose to provide an alternative recommendation for future consideration by Council. Implications: This option could delay the progress of the project, result in additional project costs and/or prevent the completion of a Flood Study within the project timeframe.

Background The Currarong Creek catchment and associated tributaries are located in the Currarong township. The objective of this study is to improve understanding of flood behaviour and impacts, and better inform management of flood risk in the study area in consideration of the available information. The study will also provide a sound technical basis for any further studies if this is found to be required. No previous flood studies have been completed for Currarong Creek. The need for a Flood Study for Currarong Creek was identified as part of Council’s floodplain programme. The study outputs will inform decision making for investing in the floodplain, managing flood risk through prevention, preparedness, response and recovery activities, and informing and educating the community on flood risk and response to floods.

Current Status of the Project Water Modelling Solutions (WMS) were engaged to prepare the Currarong Creek Flood Study in November 2018. WMS have recently issued a Draft Flood Study report and associated mapping, and this has been reviewed by Council and DPIE Floodplain Engineers. The design event flood modelling has been completed for the full range of design flood events from 20% Annual Exceedance Probability (AEP) to the Probable Maximum Flood (PMF). The hydrological and hydraulic

Southern Floodplain Risk Management Committee – Wednesday 25 November 2020 Page 13 models have been calibrated against a number of historic flood events and found to provide a reasonable overall calibration.

Community Engagement The first round of community consultation was undertaken between December 2018 and January 2019. A project website was published by Council’s Get Involved Page to inform the community about the Flood Study. This page was designed to get the feedback from community about their flooding experience within the catchment. Only a couple of residents participated in this survey. Now that Floodplain Risk Management Committees have been formed, updates will continue to be reported to and discussed with members of this committee. Following the completion of the Draft Currarong Creek Flood Study, community consultation will be undertaken through both a presentation to the Floodplain Risk Management

Committee and a public exhibition period in 2021.

Financial Implications The Currarong Creek Flood Study is 2/3 funded by DPIE and 1/3 funded by Council. There have been no increases in project cost beyond the original approved funding.

SFM20.6

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SFM20.7 Millards Creek Flood Study Update

HPERM Ref: D20/488448

Section: Environmental Services Approver: Phil Costello, Director - City Development

Reason for Report To provide the recently formed Floodplain Risk Management Committee with an update of the Flood Study for Millards Creek.

Recommendation (Item to be determined under delegated authority)

That the Committee receive the Millards Creek Flood Study report for information.

Options 1. The Committee receive the report for information. Implications: Nil.

SFM20.7 2. The Committee could choose to provide an alternative recommendation for future consideration by Council. Implications: This option could delay the progress of the project, result in additional project costs and/or prevent the completion of a Flood Study within the project timeframe.

Background The Millards Creek catchment and associated tributaries are located in Ulladulla, and discharges to the Tasman Sea through the Ulladulla Harbour. The objective of this study is to improve understanding of flood behaviour and impacts, and better inform management of flood risk in the study area in consideration of the available information. The study will also provide a sound technical basis for any further studies if this is found to be required. No previous flood studies have been completed for Millards Creek. The need for a Flood Study for Millards Creek was identified as part of Councils floodplain programme. The study outputs will inform decision making for investing in the floodplain, managing flood risk through prevention, preparedness, response and recovery activities, and informing and educating the community on flood risk and response to floods.

Current Status of the Project Water Modelling Solutions (WMS) were engaged to prepare the Millards Creek Flood Study in November 2018. WMS have recently issued a Draft Flood Study report and associated mapping, and this has been reviewed by Council and DPIE Floodplain Engineers. The design event flood modelling has been completed for the full range of design flood events from 20% Annual Exceedance Probability (AEP) to the Probable Maximum Flood (PMF). The hydrological and hydraulic

Southern Floodplain Risk Management Committee – Wednesday 25 November 2020 Page 15 models have been calibrated against a number of historic flood events and found to provide a reasonable overall calibration.

Community Engagement The first round of community consultation was undertaken between December 2018 and January 2019. A project website was published by Council’s Get Involved Page to inform the community about the Flood Study. This page was designed to get the feedback from community about their flooding experience within the catchment. Only a couple of residents participated in this survey. Now that Floodplain Risk Management Committees have been formed, updates will continue to be reported to and discussed with members of this committee. Following the completion of the Draft Millards Creek Flood Study, community consultation will be undertaken through both a presentation to the Floodplain Risk Management Committee

and a public exhibition period in 2021.

Financial Implications The Millards Creek Flood Study is 2/3 funded by DPIE and 1/3 funded by Council. There

have been no increases in project cost beyond the original approved funding. SFM20.7