Agenda of Floodplain Risk Management Advisory Committee

Reports submitted to the Floodplain Risk Management Advisory Committee to be held on Thursday 10 August 2023.

Floodplain Risk Management Advisory Committee AGENDA AND BUSINESS PAPER

Thursday 10 August 2023

ORDER OF BUSINESS:

CLAUSE PRECIS PAGE

ACKNOWLEDGEMENT OF COUNTRY 2

APOLOGIES 2

Confirmation of Minutes

CM-1 Floodplain Risk Management Advisory Committee Minutes - 8 June 2023 2

DECLARATIONS OF INTEREST 2

Reports from Staff

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

RP-2 2018-19-FM-0071 - North Wagga Flood Mitigation Options 5

RP-3 2021-22-FM-0024 - Glenfield Drain and Flowerdale Storage Flood Mitigation Works 7

RP-4 2021-22-FM-0039 - Lake Albert Flood Mitigation Options –Feasibility Study 9

RP-5 2022-FMP-0103 Humula and Mangoplah Flood Studies 10

RP-6 Local & Regional Risk Reduction Stream - Levee Pump Augmentation 11

RP-7 SW01 - Incarnie Crescent, Stormwater Augmentation - Preparing Australian Communities - Local Grant Scheme 12

RP-8 DPE Floodplain Manual Revision 13

QUESTIONS WITH NOTICE 83

ACKNOWLEDGEMENT OF COUNTRY

APOLOGIES

Confirmation of Minutes

CM-1 Floodplain Risk Management Advisory Committee Minutes - 8 June 2023

Recommendation

That the Minutes of the proceedings of the Floodplain Risk Management Advisory Committee Meeting held on 8 June 2023 be confirmed as a true and accurate record.

Attachments

1 ⇩.

Minutes - FRMAC - 8 June 2023

DECLARATIONS OF INTEREST

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 10 August 2023

RP-1

Reports from Staff

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

Author: Andrew Mason

Executive: Phil McMurray

Summary:

The project is progressing as per the required program. Preliminary fieldwork and analysis has been completed

Recommendation

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

Report

Royal HaskoningDHV (RHDHV) have now completed the majority of the background investigations, this includes:

· Site inspection of the proposed levee alignment.

· Geotechnical investigations and boreholes along the alignment.

· Survey investigation of the levees.

· Services investigation of the levees.

· Review of hydraulic modelling files including results.

This information is being processed and they have commenced some concept design optioneering of the proposed works.

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/AN/A

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 10 August 2023

RP-2

RP-2 2018-19-FM-0071 - North Wagga Flood Mitigation Options

Author: Andrew Mason

Executive: Phil McMurray

Summary:

The project is progressing well and reaching some critical milestones in the next few weeks including the major community consultation workshop and forum.

Recommendation

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

Report

Key events that have occurred in the last couple of weeks include:

· organisation of Councillor Workshop and public forum

· recruitment for public forum and targeted interviews

o there has been an enthusiastic response by residents in North Wagga willing to participate in the forum.

· development of workshop and forum information packages

· further detailed environmental analysis by NGH to provide an approximate economic cost for option L4B. This extra work will cost $27,775 incl GST.

This environmental analysis will allow for the development of an approximate economic cost of the environmental work required for option L4B.

If Option L4B is the preferred option from the feasibility study, then the Biodiversity Assessment work completed for this study will then determine if a significant impact is considered likely. If so, a Species Impact Statement or a Biodiversity Development Assessment Review (BDAR) or a referral to the Commonwealth Environment Department may be required. If no significant impact is anticipated a Review of Environmental Factors can be prepared.

A BDAR will have a cost of approximately $100,000 and a timeframe for completion of 12-14 months.

A Biodiversity Development Assessment Report (BDAR) is a report document prepared by an Accredited Biodiversity Assessor consultant that identifies how a proponent of a Development Application (DA) or State Significant Development (SSD) in New South Wales, Australia will avoid, minimise and offset impacts from their proposed development upon native vegetation or threatened species listed under the New South Wales Biodiversity Conservation Act 2016 and the NSW Biodiversity Conservation Regulation 2017. The BDAR addresses the requirements of the NSW Biodiversity Offset Scheme.

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 10 August 2023

RP-3

RP-3 2021-22-FM-0024 - Glenfield Drain and Flowerdale Storage Flood Mitigation Works

Author: Andrew Mason

Executive: Phil McMurray

Summary:

Lyall and Associates have provided an update on the project. It indicates there may be a need for cost and budget variations.

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

From Lyall and Associates:

We have reviewed the Wagga MOFFS TUFLOW Model and advise that the following updates are required so that it is fit for undertaking the Glenfield Road Drain feasibility study:

· 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, while we have not completed the assessment, we also anticipate that it will be necessary to update the way buildings are represented in the model and the invert levels of the already modelled piped drainage system.

Note that we have already made the following updates to the Wagga MOFFS TUFLOW Model as part of the work that we are currently undertaking for Council in regards the proposed redevelopment of No. 190-205 Morgan Street:

· Incorporate the latest (2020) LiDAR survey data as the base model to define the topography in the study area (note that the Wagga MOFFSS model relied on LiDAR survey data that were captured in 2008).

· Update details of the pipes through the levee at the Flowerdale Storage Area in order to assess flood behaviour in the lower reaches of the Glenfield Road Drain catchment when the river levels are not elevated.

· Incorporate details of the existing pump in the Flowerdale Storage Area in order to assess flood behaviour in the lower reaches of the Glenfield Road Drain catchment when the Murrumbidgee River is in flood.

· We have removed Areal Reduction Factors (as they are not suitable in the study area) from the hydrologic model that was used to derive inflow hydrographs to the Wagga MOFFS TUFLOW Model. The hydrologic model has been rerun and discharge hydrographs has been exported for input to the TUFLOW model.

Other potential updates to the hydrologic model that are recommended, but which may need to form part of a future scope of work given programme related time constraints imposed by DPE include:

· Refine the sub-catchment boundaries across the urbanised parts of the study area based on the details of the piped drainage system and localised topographic features that influence overland flow (such as the crown of the road).

· Update the hydrologic model so that the urbanised sub-catchments are modelling using a hydrologic model that has been developed to derive runoff from developed sub-catchments (such as the IL-CL model in DRAINS).

We have been liaising with Councils Principal Engineer Design Services, Bede Lane, as to whether there are any additional survey requirements, our surveyor has advised that he will be in the field commencing Monday 21 August 2023 to undertake the basin survey. Our surveyors will advise Council of stormwater structures that are inaccessible by hand, with mechanical assistance to be provided that will enable access to structures that the surveyors are unable to lift. Locations where additional survey may be required are also being identified, that these areas may be captured during this time. As this work will attract additional costs, we will advise you of the outcomes of our discussions with Bede once our investigations are completed.

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 10 August 2023

RP-4

RP-4 2021-22-FM-0039 - Lake Albert Flood Mitigation Options –Feasibility Study

Author: Andrew Mason

Executive: Phil McMurray

Summary:

There is a slight delay in this project while the procurement and contract process are finalised.

Recommendation

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

Report

A workplan and cost variation has been submitted to DPE for approval. Once this is finalised the consultant will be able to commit resources to this project as per their workplan and program.

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 10 August 2023

RP-5

RP-5 2022-FMP-0103 Humula and Mangoplah Flood Studies

Author: Andrew Mason

Executive: Phil McMurray

Summary:

The procurement process has been completed and a preferred consultant has been determined.

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

The procurement process for this project has been finalised and a Workplan will be provided to DPE for approval before the consultant is fully appointed to this project. At this point in time the grant for this project is $80,000 and we have expended $26,000 on the procurement of LiDar data. The consultant budget for this project is in excess of $100,000 and so a minor variation will need to be submitted to DPE as a part of the approval process.

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 10 August 2023

RP-6

RP-6 Local & Regional Risk Reduction Stream - Levee Pump Augmentation

Author: Andrew Mason

Executive: Phil McMurray

Summary:

A consultant has been appointed for this project.

Recommendation

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

Report

Stantec are the preferred consultant of this project and Council is awaiting a workplan and program from the consultant for this project to begin.

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

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 10 August 2023

RP-7

RP-7 SW01 - Incarnie Crescent, Stormwater Augmentation - Preparing Australian Communities - Local Grant Scheme

Author: Andrew Mason

Executive: Phil McMurray

Summary:

This project has been handed over to the Sewer and Stormwater team for implementation

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the Incarnie Crescent Stormwater Augmentation project.

Report

The design has been completed and this project is currently with the Council Sewer and Stormwater team for implementation.

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

Report submitted to the Floodplain Risk Management Advisory Committee on Thursday 10 August 2023

RP-8

RP-8 DPE Floodplain Manual Revision

Author: Andrew Mason

Executive: Phil McMurray

Summary:

DPE have issued a new Flood risk management manual.

Recommendation

That the Floodplain Risk Management Advisory Committee receive and note the update provided in relation to the update of the Flood Risk Management Manual by the NSW Department of Planning and Environment.

Report

Flooding results in significant risk to many communities across New South Wales. This risk stems from human interaction with flooding through the occupation and use of floodplains.

Since 1984 the NSW Flood Prone Land Policy (the policy) has set the direction for Flood Risk Management (FRM) in New South Wales. In 1986 the NSW Government released the first Floodplain Development Manual to support policy implementation. The policy and manual have since evolved in response to significant flood events, reviews and improvements in national and international flood risk management practice.

The policy as outlined in this document sets the direction for FRM in New South Wales. The Flood Risk Management Manual: the Policy and Manual for The Management of Flood Liable Land (this manual) and its toolkit support the implementation of the Policy through the combined efforts of all levels of government.

This manual (including the policy) replaces the Floodplain Development Manual (DIPNR 2005) as the NSW Government’s manual relating to the management of flood liable land in accordance with section 733 of the Local Government Act 1993 (LG Act). This provides councils, statutory authorities, and state agencies and their staff, with indemnity for decisions they make and information they provide in accordance with the manual.

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