Agenda of Floodplain Risk Management Advisory Committee

Reports submitted to the Floodplain Risk Management Advisory Committee to be held on Thursday 7 November 2024.

Floodplain Risk Management Advisory Committee AGENDA AND BUSINESS PAPER

Thursday 7 November 2024

ORDER OF BUSINESS:

CLAUSE PRECIS PAGE

ACKNOWLEDGEMENT OF COUNTRY 2

APOLOGIES 2

Confirmation of Minutes

CM-1 FLOODPLAIN RISK MANAGEMENT ADVISORY COMMITTEE MINUTES - 8 AUGUST 2024 2

DECLARATIONS OF INTEREST 2

Reports from Staff

RP-1 2021-22-FM-0032 - Uranquinty Levee Upgrade - Investigation and Design 3

RP-2 2023 FMP 0073 Early Warning System Model Development 5

RP-3 2018-19-FM-0071 - North Wagga Flood Mitigation Options 6

RP-4 2021-22-FM-0024 - Glenfield Drain and Flowerdale Storage Flood Mitigation Works 8

RP-5 2021-22-FM-0039 - Lake Albert Flood Mitigation Options - Feasibility Study 10

RP-6 2022-FMP-0103 Humula and Mangoplah Flood Studies 12

RP-7 Reconnecting River Country Program 53

RP-8 Local & Regional Risk Reduction Stream - Levee Pump Augmentation 55

RP-9 Flood Project Implementation Status 93

QUESTIONS WITH NOTICE 116

ACKNOWLEDGEMENT OF COUNTRY

APOLOGIES

Confirmation of Minutes

CM-1 FLOODPLAIN RISK MANAGEMENT ADVISORY COMMITTEE MINUTES - 8 AUGUST 2024

Recommendation

That the Minutes of the proceedings of the Floodplain Risk Management Advisory Committee Meeting held on 8 August 2024 be confirmed as a true and accurate record, noting Council’s adoption of these minutes at its meeting 26 August 2024.

Attachments

1 ⇩.

Floodplain Risk Management Advisory Committee Minutes - 8 August 2024

117

DECLARATIONS OF INTEREST

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-1

Reports from Staff

RP-1 2021-22-FM-0032 - Uranquinty Levee Upgrade - Investigation and Design

Author: Andrew Mason

Director: Warren Faulkner

Summary:

The project is progressing as per the required program. The preliminary design has been completed but costings for the cost benefit analysis have not been finalised.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Uranquinty Levee project.

Report

Royal Haskoning DHV (RHDHV) have completed the preliminary design and conducted their first and second rounds of community consultation in Uranquinty. The second round of community consultation was conducted on the 13th August 2024 at Uranquinty in conjunction with the Uranquinty Progress Association.

Council is investigating changing the alignment of the eastern levee so that it protects land that is zoned RU5 to allow for village expansion. The revised levee alignment has the potential to protect approximately an extra 50 “1/4 acre blocks.

RHDHV has provided an estimate to complete the analysis as extra work and if the cost to protect the land proves viable and appropriate mitigation can be put in place, there will be a variation request put into the Department of Climate Change, Energy, the Environment and Water (DCCEEW) once this is received.

There is limited scope in the remaining grant allocation to cover this extra cost and so Council will have to cover some of this extra work from internal funds.

Andrew Morris from RHDHV will provide a short presentation on the status of the current design and Council staff will provide an overview of the options being considered for the eastern levee.

Financial Implications

There may need to be a variation to the project budget for the change of scope requested for the eastern levee.

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

N/A

Internal / External Consultation

N/AN/A

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-2

RP-2 2023 FMP 0073 Early Warning System Model Development

Author: Andrew Mason

Director: Warren Faulkner

Summary:

This Report provides an outline of the Early Warning System Model Development 2023 FMP 0073

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the report with regard to the Early Warning and flood Prediction Project.

Report

This project is a development of a recommendation from the 2018 FRMSP. An initial project was completed by Stantec and this has been developed into a specific and targeted approach to improve accessibility to flood and river data for the Council, the SES and the general public. The approach is to enhance and improve existing Council systems and work collaboratively with the SES and BOM to improve access to data across the LGA and the wider catchment.

Cameron Druery from Worley will be providing a short presentation about WaterRide, an existing Council software package that will be enhanced and improved through this project.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Monitor and enforce public safety

Risk Management Issues for Council

N/A

Internal / External Consultation

N/A

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-3

RP-3 2018-19-FM-0071 - North Wagga Flood Mitigation Options

Author: Andrew Mason

Director: Warren Faulkner

Summary:

This project has been finished and closed with DCCEEW receiving the final repots and the funding finalised.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update to the North Wagga Flood Mitigation Options.

Report

This project has been finalised and closed out with DCCEEW.

An indicative timeline for the implementation of the raised levee and third party mitigation options is provided below.

Stage	Duration	Commencement
Topographic Survey	6 months	August 2024
Environmental Assessment	4 months	November 2024
Floodgate Pipe Relining	3 Months	March 2025
Civil Design including mitigation options for residents adversely affected by the levee raising	12-15 months	July 2025
Levee contractor procurement	4 months	November 2026
Levee construction	24 months	March 2027

A new project specifically about the implementation of the levee raising and third-party mitigation options will be developed and adopted by Council. This project will be reported on at the next meeting of FRMAC in 2025.

The detailed survey for the levee design is well underway and should be finished shortly.

The Review of Environmental Factors is programmed to begin shortly and will take approximately 8 weeks to complete.

Financial Implications

N/A

Policy and Legislation

Local Government Act

Development Control Plan 2010

Flood Risk Management Manual

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

N/A

Internal / External Consultation

The Committee are advised that the consultants will attending this meeting remotely and presenting via zoom.

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-4

RP-4 2021-22-FM-0024 - Glenfield Drain and Flowerdale Storage Flood Mitigation Works

Author: Andrew Mason

Director: Warren Faulkner

Summary:

Lyall and Associates have provided an update on the project.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Glenfield Drain and Flowerdale Storage Area Flood Mitigation Works Project.

Report

To ensure the MOFFS model is providing more reliable outputs and reflects more accurately overland flood behaviours, Lyall and associates recommended that the 2021 model provided to them be updated to:

· Reduce the cell size to 2.5 m (from 5 m) to more accurately define the capacity of the overland flow paths.

· Incorporate additional stormwater pits and pipes, particularly in the headwaters of the study area to ensure that the rate and volume of runoff that discharges to each detention basin is accurately represented.

· Update the location where the discharge hydrographs are injected into the TUFLOW model.

In addition to the above, Lyall & Associates also anticipated that it would be necessary to update the way buildings are represented in the model and the invert levels of the already modelled piped drainage system.

A variation to the contract was approved in February 2024 to update the model.

Lyall and Associates update for this report is:

The hydrologic and hydraulic models have undergone a final QA check, with all the necessary updates having been made with the exception of a few pipe/culvert details that we are awaiting from Council.

We have started compiling figures for the report, the first of which highlight the key features of each stormwater detention basin within the catchment.

Lyall and Associates have advised that their program is currently running about a fortnight out of sync with the revised timeline submitted to the 15 February 2024 FRMAC meeting, however they should still be able to complete this project in July 2025.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

N/A

Internal / External Consultation

N/A

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-5

RP-5 2021-22-FM-0039 - Lake Albert Flood Mitigation Options - Feasibility Study

Author: Andrew Mason

Director: Warren Faulkner

Summary:

Work on this project has commenced and Stantec are working on the project in line with the program

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Lake Albert Flood Mitigation Project.

Report

From Stantec:

Completed tasks to date:

· Data review and FRMS&P model review, summarised in a Stage 1 report

· Initial environmental assessment summarised in a draft summary report

· Initial stakeholder consultation with directly affected organisations (boat club, sailing club, country club and dragon boat club) completed on 1 and 2 August, attended by Council and Stantec

· Council has provided survey data to calibrate LiDar information to existing channel centrelines

Using feedback from these initial stakeholder discussions completed recently, we can proceed with initial review and update of preliminary design. Next steps include:

· Initial community consultation, to commence in the next several months, consultation materials have been drafted

· Preliminary design of combined option and updated flood modelling

· Site investigations including Geotech investigations and utilities assessment

The interaction of this project with both the Plumpton Rd upgrade and River to the Lake project will cause some minor disruption but should not delay the outcome of this analysis.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

N/A

Internal / External Consultation

N/A

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-6

RP-6 2022-FMP-0103 Humula and Mangoplah Flood Studies

Author: Andrew Mason

Director: Warren Faulkner

Summary:

WMAWater have commenced the study for Humula and Mangoplah and have conducted initial community consultation in the villages .

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Humula and Mangoplah Flood Studies Project.

Report

Council engaged WMAwater in late September 2023, to undertake the Humula and Mangoplah Flood Study.

The relevant LiDar data has been provided to WMAWater for development of the flood models .

WMAWater have built hydrologic models for both towns and have a hydraulic model for Mangoplah. Calibration for Mangoplah has commenced. The hydraulic built for Humula is ongoing.

Community Consultation was conducted at Humula on the 4 September 24 and Humula on the 5 September 2024.

Milestone Report 1 is attached to this business paper.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

N/A

Internal / External Consultation

N/A

Attachments

1 ⇩.

Mangoplah and Humula - Stage 1 Milestone Report

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-6

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-7

RP-7 Reconnecting River Country Program

Author: Warren Faulkner

Summary:

Reconnecting River Country Program.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Reconnecting River Country Program being carried out by DCCEEW

Report

A report was provided to the FRMAC at its 8 August 2024 meeting that provided an overview of the Reconnecting River Country Program.

The program is in development. No flows have been delivered under the program and no decision has been made to select a flow option. No higher environmental flows will be delivered before December 2026.

The program is funded to prepare a Murrumbidgee Final Business Case by February 2025. This will recommend a flow option for delivery. The Final Business Case must be considered before proceeding to delivery.

In July 2024, funding was announced to upgrade a 1.5km section of Mundowy Lane to be resilient to flows up to 45 GL/day.

At the 28^th October 2024 Ordinary Meeting of Council, Council received a Notice of Motion concerning the Reconnecting River Country Program and resolved as follows:

a take up the request to receive an in person update and workshop on what this Reconnecting Rivers Country Program involves and the effects on our Local Government Area (LGA) and our residents

b following the workshop, write to:

i. the NSW Minister for Water, Housing and Homelessness the Hon Rose Jackson MLC, requesting an immediate halt in the Reconnecting River Country Program.

ii. all other RAMJO Councils and any other Council’s located on the Murrumbidgee River, seeking feedback and support of our situation in this matter

iii. the Shadow Minister for Water Steph Cooke MP, requesting her knowledge and position on this issue

c receive a report on the Reconnecting River Country Program that includes a complete list of where proposed consultation for the Landholder Negotiation Scheme was advertised

Council received a briefing from representatives of DCCEEW on Wednesday 30 October 2024.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

N/A

Internal / External Consultation

N/A

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-8

RP-8 Local & Regional Risk Reduction Stream - Levee Pump Augmentation

Author: Andrew Mason

Director: Warren Faulkner

Summary:

Stantec have finalised their work on this project and a report and outcomes have been provided to Council.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Levee Pump Augmentation Project.

Report

Stantec have completed extensive analysis of the four floodgates and determined that floodgates 8 and 25 are a priority. They have completed damage assessments across the two catchments to enable the determination of a BCR balanced across the risk appetite, time of inundation, capital cost of the pumps and required infrastructure, and perceived utilisation of the pumps under flood conditions.

The detailed analysis from Stantec has provided a preliminary design at each location for a pump and pit structure. It has provided specific information about floodgate 8 which will be incorporated into the Incarnie stormwater project and the upgrade of floodgate 7.

The pump required to remove the water in a timely manner from floodgate 25 is too large and expensive to be cost effective. The next stage of this project is for Council staff to determine an appropriate mitigation option for the catchment of floodgate 25 that may include significant onsite detention and appropriate more cost-effective pump options.

The Stantec memorandum and preliminary design for pump and pit locations for this project is attached to this business paper.

Stantec have also been developing an inundation model for the area around gate 25 for when the Kooringal Road Spillway comes into effect in a 0.20% AEP event.

The outcome of this analysis is attached to this business paper.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Community leadership and collaboration

Objective: Wagga Wagga has strong community leadership and a shared vision for the future

Plan long term for the future of Wagga Wagga

Risk Management Issues for Council

N/A

Internal / External Consultation

N/A

Attachments

1 ⇩.	Levee Pump Augmentation Concept Plans
2 ⇩.	Levee Pump Augmentation Technical Memo Damage Assessment
3 ⇩.	Kooringal Spillway Assessment-1in200yr

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 7 November 2024

RP-9

RP-9 Flood Project Implementation Status

Author: Andrew Mason

Summary:

This Report outlines the status of the flood projects across the various studies that Council currently has underway.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the report in relation to Flood Project Implementation Status.

Report

Council has over 60 recommendations from the three recently completed studies and is working its way through the studies. The spreadsheet tracking these projects is an attachment to this report.

With regard to RE3 from the 2018 FRMSP and RM04 from the 2021 MOFFS, Council staff will be presenting the current status and type of information available on the Council web page with regard to flooding and a brief outline of the future direction for this page.

Financial Implications

N/A

Policy and Legislation

N/A

Link to Strategic Plan

Safe and Healthy Community

Objective: Our community feel safe

Be responsive to emergencies

Risk Management Issues for Council

As outlined in the Report.

Internal / External Consultation

N/A