AGENDA AND BUSINESS PAPER

 

 

Floodplain Risk Management Advisory Committee

 

 

 

To be held on
Tuesday 7 May 2019

AT 8.30am

 

 

 

Cnr Baylis and Morrow Streets,
Wagga Wagga NSW 2650
PO Box 20, Wagga Wagga

 

Phone: 1300 292 442
Fax: 02 6926 9199
Website:
www.wagga.nsw.gov.au

 


Reports submitted to the Floodplain Risk Management Advisory Committee to be held on Tuesday 7 May 2019.

Floodplain Risk Management Advisory Committee AGENDA AND BUSINESS PAPER

Tuesday 7 May 2019

ORDER OF BUSINESS:

CLAUSE               PRECIS                                                                                            PAGE

ACKNOWLEDGEMENT OF COUNTRY                                                                              2

APOLOGIES                                                                                                                      2

Confirmation of Minutes                                                                                          2

DECLARATIONS OF INTEREST                                                                                        2

Reports from Staff

RP-1            Project Updates                                                                                      3

QUESTIONS WITH NOTICE 


ACKNOWLEDGEMENT OF COUNTRY

 

 

APOLOGIES

 

 

Confirmation of Minutes

CM-1              Meeting Minutes - 5 February 2019       

 

Recommendation

That the Minutes of the proceedings of the Floodplain Risk Management Advisory Committee held on 5 February 2019 be confirmed as a true and accurate record.

 

 

Attachments

 

1.

Meeting Minutes - 5 Febraury 2019

9

   

 

 

DECLARATIONS OF INTEREST


Report submitted to the Floodplain Risk Management Advisory Committee on Tuesday 7 May 2019.                          RP-1

 

Reports from Staff

RP-1               Project Updates

Author:          Peter Ross 

Director:       Caroline Angel

         

 

Analysis:

This report is to provide an update on the following projects:

·     Wagga Wagga Major Overland Flow Flood (MOFF) Risk Management Study and Plan

·     Main City and North Wagga Levee Construction – Stage 1

·     Wagga Wagga Revised Floodplain Risk Management Study and Plan

·     Wagga Wagga Villages Floodplain Risk Management Study and Plan

 

The following projects have been submitted for grant funding:

·     Humula and Mangoplah Flood Studies & Floodplain Risk Management Studies and Plans (comprises two applications)

·     Wagga Wagga Flood Warning System Improvements Investigation

 

 

 

Recommendation

That the Committee receive and note the report

 

Report

Project 1753 – Wagga Wagga Major Overland Flow Flood (MOFF) Risk Management Study and Plan

 

An application was made on 21 February 2019 for a variation to the existing approved grant funding for this project to undertake Australian Rainfall and Runoff 2016 (ARR2016) work on the existing flood model. The variation was for a three-month extension in time and an increase in Government funding to undertake the work. Formal advice received confirms that the three-month extension has been granted.

 

WMAwater have now completed the full update of the MOFFRMS&P to incorporate the ARR 2016 methodologies and revised Stage 1 and 2 reports based on the ARR2016 results.

 

WMAwater will be attending the Floodplain Risk Management Advisory Committee (FRMAC) meeting on Tuesday 7 May 2019 to advise of progress to date and to present and discuss Stage 1 and 2 reports with the Committee (Report 1Data Collection & Model Review Report and Report 2 – Flood Damages Assessment Report.

 

 

 

Project 1793 – Main City and North Wagga Levee

 

The upgrade of the remaining 6km of levee between Gobbagombalin Bridge and Hammond Avenue is the second part of this lengthy and complex project. The aim is to provide a 1 in 100-year flood protection to the city for the first time.

Stage 2 works involve the extension and reinforcement of existing concrete retaining walls and installation of capped sheet piles.

 

The sheetpiles between Cadell Place and Johnston Street have been installed and adjusted for height. The capping of these piles should commence shortly.

 

The concrete wall extension along Cadell Place has been completed.

The carpark at Crampton Street has been reopened and the cribwall, stairs and footpath completed recently.

 

The Narrung St bank is nearing completion and the area along the dog track is on track for completion shortly.

 

The Wiradjuri Walking Track will be completely closed for several months in this section from 7 January 2019.

 

Residents and business operators affected by the works, or anyone interested in the Stage 2 levee project, are invited to attend a community information session to be held on 30 May 2019.

 

Council staff are working with the contractors to minimise disruptions as much as possible and thank residents and businesses for their cooperation throughout these works.

 

The Stage 2 upgrade is scheduled to take approximately 14 months, weather dependant.

 

 

Project 2000 – Wagga Wagga Revised Floodplain Risk Management Study and Plan

 

Updates to FRMS&P Mitigation Measures

 

Options PR1 & L4B

PR1: Undertake a feasibility study to investigate a Voluntary House Raising & Voluntary House Purchase Scheme in Wagga Wagga Study Area, in conjunction with, North Wagga Levee Upgrade to 5% AEP level of protection WITH an equivalent upgrade to Hampden Avenue (as embankment) and conveyance improvements through Wilks Park.

 

L4B: Undertake a feasibility study to investigate North Wagga Levee Upgrade to 5% AEP level of protection WITH an equivalent upgrade to Hampden Avenue (as embankment) and conveyance improvements through Wilks Park, in conjunction with, Voluntary House Raising & Voluntary House Purchase Scheme in Wagga Wagga Study Area.

 

Council has received grant funding from OEH to undertake the feasibility study of these two options. Development of the brief has commenced and it is proposed that it will be presented at the next FRMC meeting for consideration by the committee.

 

RE1: Improve Flood Warning System

Council has made a grant application to investigate options to improve our riverine flood warning system.  The project will:

 

-     review the current flood warning system

-     assess and scope deficiencies in the current flood warning system

-     make recommendations on additional infrastructure needs and any other improvements

 

Project 18640 – Wagga Wagga Villages Floodplain Risk Management Study and Plan

 

Stage 1 report has been submitted by GRCHydro and distributed to OEH, relevant Council staff and FRMAC members for comment.  Council staff met with GRCHydro on Wednesday 17 April 2019.  Responses to the questionnaire that had been sent to village residents was discussed and reviewed. GRCHydro requested further information in relation to:

-     existing “levees” at the villages,

-     cross drainage through levees

-     access to community representatives that could be utilised as information conduits to the broader village communities

-     levee inspection information

-     possible draft DCP/LEP recommendations resulting from the MOFFS project

-     comments received which refer to the Tarcutta By-pass and flooding.

 

GRCHydro then undertook an inspection of each of the villages.

 

Project 19555 – Flood Mitigation Option Feasibility Study for North Wagga & Floodplain Residents

 

Council staff are working on the development of the scope and brief for this project. Given the nature of the options to be investigated as part of the study, there is a level of complexity that needs to be fully considered and understood to ensure practical outcomes from the study.

 

As noted in Project 2000 above, it is proposed that the scope and brief for this project will be presented to the Committee for consideration at the next FRMC meeting.

 

2019-2020 Floodplain Management Program

 

A grant application has been submitted for Humula and Mangoplah Flood Studies & Floodplain Risk Management Studies and Plans (FRMS&P). The flood study will produce information on flood levels, velocities, flows, hydraulic categories and provisional hazard categories for a full range of flood events. The FRMS&P will assist Council in developing strategic plans for mitigating and managing the effects of existing, future and continuing flood risk.

For context, the following should be noted:

 

 

Humula is subject to flooding from the Umbango, Carabost & Murraguldrie Creeks. The Flood Intelligence Collection Report (2011) prepared by Bewsher Consulting on behalf of the SES identified that in October 2010 flood, it was found that the observed rainfall for Carabost and Humula stations in the Umbango catchment exceeded the 100 year ARI frequency for the 72 hour duration. However, the average return period for an 18 hour storm duration was 20-50 years.

 

Mangoplah floods primarily from Burkes Creek. Burkes Creek has had a telemetary gauge installed at Mangoplah since 2014 as part of The Rock Flood Warning System managed by Lockhart Shire Council. No major flood has occured in Burkes Creek since this gauge was installed, so no records exist of past floods. However, based on the responses of the community questionnaires that was a part of the Flood Intelligence Collection Report (2011) prepared by Bewsher Consulting on behalf of the SES, no one in the Burkes Creek catchment could recall higher flooding than what occurred in October 2010. The height at Mangoplah was many metres higher than any previous known flood event. The subsequent March 2012 event peaked some 0.4m lower than the 2010 event.

 

At The Rock the 2010 flood event was determined to be equivalent to a 300yr ARI event whereas the March 2012 event was determined to be equivalent to a 500yr ARI event. This differential was determined to be due to the higher tributary flows experienced downstream of Mangoplah during the later event.  

 

Financial Implications

The total project budgets, expenditure and commitments to date are as follows:

Project name

Total Project Budget

Expended + Committed as at

30 April 2019

Budget Remaining

Wagga Wagga Major Overland Flow Flood (MOFF) Risk Management Study and Plan

FM-0099 - (17826)

$220,001

$214,473

$5,528

Main City Levee Construction – Stage 1 (17843) *

$3,278,231

$3,561,894

$-

Wagga Wagga Villages Floodplain Risk Management Study and Plan

FM-115 - (18640)

$198,000

$142,613

$55,387

North Wagga Flood Mitigation Study 2018-19-FM-0071 – (19555)

$234,000

$0.00

$234,000

 

*Main City Levee Construction – Stage 1 is showing expenditure at $3.562M, as the project includes expenditure incurred on the Kooringal Road Cycleway, which Council expects to receive approximately $157K in grant funding from the RMS, which will require 50:50 Council Reserves funding.

 

 

 

 

 

Policy and Legislation

The outcomes from the various studies will be very important in the terms of future amendments to the Council Local Environmental Plan and its Development Control Plan.

 

Link to Strategic Plan

Community Leadership and Collaboration

Objective: We are active community members

Outcome: We recognise we all have a role to play

 

Risk Management Issues for Council

There is a risk that the cost to carry out these projects could be more than was originally estimated. Therefore, Council would need additional funds to complete the works. However, some contingency was built into all of the estimates to reduce this risk

Internal / External Consultation

The Office of Environment and Heritage have been heavily consulted throughout the process of planning and executing these projects.

 

NSW Emergency Management is the responsible funding body and receives quarterly status update reports.

 

NSW State Emergency Services and Bureau of Meteorology are consulted when required.

 

Each of these projects is managed using a project steering group made up of members from different areas of Council as per Councils project management methodology.

 

Council officers in various directorates are members of the project steering committees for each project.

 

 

  

 

   


QUESTIONS WITH NOTICE 

 


Reports submitted to the Floodplain Risk Management Advisory Committee to be held on Tuesday 7 May 2019.