AGENDA AND BUSINESS PAPER

 

 

Floodplain Risk Management Advisory Committee

 

 

 

To be held on
Tuesday 18 June 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 18 June 2019.

Floodplain Risk Management Advisory Committee AGENDA AND BUSINESS PAPER

Tuesday 18 June 2019

ORDER OF BUSINESS:

CLAUSE           PRECIS                                                                                                PAGE

ACKNOWLEDGEMENT OF COUNTRY                                                                              2

APOLOGIES                                                                                                                      2

Confirmation of Minutes

CM-1                Meeting Minutes - 7 May 2019                                                             2

DECLARATIONS OF INTEREST                                                                                        2

Reports from Staff

RP-1                 Project Updates                                                                                 3

QUESTIONS WITH NOTICE                                                                                               18


ACKNOWLEDGEMENT OF COUNTRY

 

 

APOLOGIES

 

 

Confirmation of Minutes

CM-1              Meeting Minutes - 7 May 2019       

 

Recommendation

That the Minutes of the proceedings of the Floodplain Risk Management Advisory Committee held on 7 May 2019 be confirmed as a true and accurate record.

 

 

Attachments

 

1.

Meeting Minutes - 7 May 2019

19

   

 

 

DECLARATIONS OF INTEREST


Report submitted to the Floodplain Risk Management Advisory Committee on Tuesday 18 June 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

 

 

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 had previously been received confirming that the three-month extension was granted, however the request for additional funding was not approved.  Following a request from Council to review the funding decision, formal advice has now been received confirming approval for the original funding increase request.  The total project cost is now $228,940.00 (Refer attachment MOFF’s Program Ver 5.1).

 

Following the last Committee meeting, planning workshops were held regarding the definition of the Flood Planning Area in overland flow affected areas and preliminary results of mitigation options assessed in and around Lake Albert and Glenfield Drain.

 

Outcomes from the Workshop are as follows:

 

1.        Major Overland Flow Flood Planning Area:

a.      to be defined as the extent of the 1% AEP event excluding areas affected by depths of less than 150 mm;

b.      WMAwater to confirm this extent would not exclude any areas categorised as Floodway or high hazard (H5-H6), and amend if necessary to ensure these are incorporated;

c.       WMAwater to prepare Flood Planning Area Maps for each MOFFRMS domain;

d.      Discussion about the riverine flood risk inside the levee in flood events that overtop the levee (or in the event of unexpected levee failure) – Critical Facilities/Utilities in particular should consider this ‘residual flood risk’. Commercial properties in east wagga are likely also to be subject to both riverine and overland flow flood risk. Council will be provided with the necessary information to understand the full range of flood risk at such locations.

 

2.      Major Overland Flow Flood Planning Level

a.      Brief discussion about using a freeboard of 0.3 m for overland affected areas (rather than 0.5m freeboard typically used in mainstream affected areas and applied from the Riverine FRMS);

b.      WMAwater to undertake a Freeboard Assessment to determine the suitable freeboard;

 

3.      Future Development Areas

a.      Council has provided GIS files to WMAwater –these will be mapped in relation to various design flood outputs to identify any constraints or flood issues.

 

Preliminary Mitigation Options

WMAwater are currently looking at flood modification options in the Lake Albert and City areas:

1.   Lake Albert

a.    Options are being considered to investigate the impacts of diverting a greater proportion of flow from Stringybark Creek and Crooked Creek into Lake Albert.

b.    First pass assessments have shown promising results, however some refinement is needed to ensure upstream properties are not adversely impacted – WMAwater is currently working on this

2.   Glenfield Drain

a.    Options are being investigated to reduce flows in the Glenfield Drain (and by extension, reduce overland flow around the Dobney Ave/ Bunnings intersection) via a range of methods.

b.    Preliminary results are promising but further refinement is needed.

c.    In addition to assessing reductions in peak flood levels, options that substantially reduce duration of inundation are also being considered and investigated.

 

The Consultants will be in attendance at the 18 June 2019 FRMAC meeting to discuss progress to date and proposed mitigation options throughout the study area.

 

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 will commence once the concrete path in the area has been completed.

 

The concrete wall extension along Cadell Place has been completed.

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

The Narrung St bank is  completed and only waiting for seeding to take place  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.

 

The sheetpiles south of the Sturt Highway and along to Kooringal road have been driven and levelled, the capping of these piles should commence shortly.

 

The earthworks between the Sturt Highway and the Riverina Water County Council pedestrian bridge has commenced in preparation for sheetpiling in this area.

 

Residents and business operators affected by the works, or anyone interested in the Stage 2 levee project attended a community information session  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 concept has been completed (please refer attachment).  The brief is still to be finalised.

 

RE1: Improve Flood Warning System

As stated at the previous meeting, Council has made a grant application to investigate options to improve our riverine flood warning system.  We are awaiting response in relation to the application, which will most likely be towards the end of the year.

 


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.  For information, program work plan for this project is attached as “VOFF’s Program”.

 

A preliminary list of mitigation measures to be modelled has been compiled for Uranquinty, Ladysmith and Tarcutta.  The list has been based on results of the questionnaire, the findings of the flood study and the Consultant’s understanding of each town’s flood behaviour.  The list for each town is detailed below.  The study budget includes modelling of a maximum of 12 different mitigation options.  The 12 italicised options are recommendations for modelling but are open to suggestion.  Other options (such as planning controls or maintenance items) will be included in the report but do not necessarily require modelling.  It should be noted that the list is a starting point, not a finalised list.

Uranquinty

 

1.      Raise levee to give protection against 1% AEP creek flooding, including freeboard

2.      Raise Connorton St and Deane St levees to give overland flow protection, including channel improvements

3.      Improve bypass channel conveyance and widen and/or deepen in sections

4.      Increase creek capacity at highway/railway crossing

5.      Increase stormwater capacity through the urban area (e.g. pit/pipe upgrade)

6.      Increase culvert capacity at Uranquinty Cross Road

7.      Upgrade levee cross drainage (multiple locations)

 

Tarcutta

 

8.      Raise existing town levee to offer 1% AEP protection

9.      Construct new levee adjacent to oval and achieve 1% AEP level of protection

10.    Assess other levee alignments and levels of protection (depending how many options were developed by RMS)

11.    Significantly reduce extent of Hambledon levee

12.    Improve overland flow path through the town with kerb/guttering, bunds or piped drainage.

13.    Increase capacity under old highway

 

Ladysmith

 

14.    Clean up sides of Monavale Road where there is currently fill

15.    Upgraded stormwater drainage in the town to reduce occurrence and extent of overland flooding.

16.    Upgraded kerb and guttering to reduce occurrence and extent of overland flooding.

 

The study is also in the process of the flood damages assessment and the flood risk assessment of emergency management and current zonings.

 

The Consultants will be in attendance at the 18 June 2019 FRMAC meeting to make a presentation.

Subsequent consultation will occur between the consultant and FRMAC representatives during modelling and development of mitigation options, before the draft study and plan is put on public exhibition for wider consultation.

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

 

Council staff have completed the scoping document for this project and are working on the development of the brief. 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.

 

The scoping document for this project is attached to this report.

 

2019-2020 Floodplain Management Program

 

As stated at the previous meeting, a grant application has been submitted for Humula and Mangoplah Flood Studies & Floodplain Risk Management Studies and Plans (FRMS&P). 

 

We are awaiting response in relation to the application, which will most likely be towards the end of the year.

 

Financial Implications

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

Project name

Total Project Budget

Expended + Committed as at

30 May 2019

Budget Remaining

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

FM-0099 - (17826)

$228,940

$214,473

$14,468

Main City Levee Construction – Stage 1 (17843) *

$3,278,231

$3,537,593

($259,362)

Wagga Wagga Villages Floodplain Risk Management Study and Plan

FM-115 - (18640)

$198,000

$141,872

$56,128

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 $3.538M, as the project includes expenditure incurred on the Kooringal Road Cycleway, which Council expects to receive approximately $156K 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.

 

Attachments  

 

1.

MOFF's Program Ver 5.1

 

2.

North Wagga Options Assessment - Rev 1 PMO Scope (002)

 

3.

VOFF's Program

 

 

 

 

 


Report submitted to the Floodplain Risk Management Advisory Committee on Tuesday 18 June 2019.                                                         RP-1

 


Report submitted to the Floodplain Risk Management Advisory Committee on Tuesday 18 June 2019.                      RP-1

 

1b. Project Scope

Project Scope – only to be completed once the Concept  is ‘Approved’

Project Background and Problem / Opportunity that this Project will address

The completion of a feasibility study for Option L4B  for a North Wagga Levee with a 5% AEP level of

protection WITH an equivalent upgrade to Hampden Avenue and conveyance

improvements through Wilks Park between North Wagga and the CBD is recommended.

 

The feasibility study would involve identifying the environmental constraints of excavating

Wilks Park to offset flood impacts, assessing the condition of the existing levee, detailed

floor survey and site by site assessment of negatively affected properties to determine

individual flood impacts and subsequently, eligibility for and suitable types of compensatory

works. Further to this, the study would also be required to consider ongoing community

education issues and engagement programs. Consideration must also be given to internal

drainage infrastructure.

 

The feasibility study will be undertaken in conjunction with Option PR1, which will assess

the feasibility of a Voluntary House Raising and Voluntary Purchase Scheme in eligible

areas of the Wagga Wagga Study Area.

 

There is a large number of dwellings in the Wagga Wagga Study Area subject to high hazard

flood conditions. A combined Voluntary House Raising and Voluntary Purchase scheme

would, over time, either raise dwellings above the FPL or remove eligible dwellings from the

area to remove residents from high hazard areas, thereby reducing instances of over-floor

flooding and hence damages.

 

The Scheme could be an alternative to Option L4B, which involves a feasibility study to assess upgrading the North Wagga Levee to the 5% AEP Level with associated access upgrade, and the two feasibility studies should be undertaken in conjunction to determine if both options are feasible, and if so, which is more viable for reducing flood risk exposure in Wagga Wagga.

 

A further component of the study as recommended by WWCC Councilors is the combination of options L4B and PR1 to ascertain the feasibility of a combined solution to combat flooding issues in and around North Wagga.

 

 

PR1: Undertake a feasibility study to investigate a Voluntary House Raising & Voluntary House Purchase Scheme in Wagga Wagga Study Area

 

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

 

WWCC Option:

Undertake feasibility studies of flood mitigation strategies including Option L4b and PR1 combined

 

What outcome(s) is the project going to deliver?

The recommended option presented in the feasibility study is aimed to establish a program for implementation of the best feasible and viable flood mitigation option to reduce the flood risk in North Wagga and the whole of Wagga Wagga's floodplain residents.

 

What is in Scope for the project?

Flood Mitigation Option Feasibility Study for North Wagga – Draft Scope of Works

Levee upgrade option assessment:

·    Collect and review all relevant data and information and collect any additional relevant data emanating from the review.

·    Develop Community Consultation Plan.

·    Preliminary Design for a 5%AEP levee upgrade with Hampden Avenue raising.

·    Detailed survey of each property inside and outside the levee.

·    Hydraulic and third party impact assessment associated with the levee and Hampden Avenue upgrade.

·    Costing, Flood Damages Assessment review and Cost/Benefit Analysis for levee upgrade option.

VHR/VP option assessment:

·    Develop criteria for assessing the viability of “at risk” dwellings for VP and/or VHR.

·    Identify properties eligible for VP and VHR both inside and outside the levee.

·    Community Consultation to gauge Community preferences for levee versus VHR/VP scheme.

·    Estimates of “market valuations” for VP eligible properties and costs to raise VHR eligible properties.

·    Review and update flood damage assessments for these “at risk” dwellings.

·    Identify and assess the viability of “at risk” dwellings suitable for VP or VHR based on the assessment criteria including:

Practicality and eligibility

Preliminary cost estimates and benefit cost estimates for VP and/or VHR for dwelling(s)

Equity

Priorities for VP and/or VHR

·    Cost/Benefit Analysis for VHR/VP option.

·    Compare the two options (levee upgrade vs VP/VHR) from a social, economic, ecological and cultural perspective.

·    Consider, develop and assess a revised option/s that encompass a combination of these options? Extensive Community Consultation needed in this phase.

·    Develop a draft Feasibility study with a recommendation for an option going forward.

·    Prepare PEPO for the preferred option.

·    Undertake further consultation with the North Wagga and Floodplain communities and the individual “at risk” dwelling owners during Public Exhibition of the draft feasibility study.

·    Finalise Feasibility Study and Council adoption.

5% AEP Wilks Park Conveyance

 

Social

Construction & Implementation

·   Appetite for levee upgrade (residents inside  and outside levee to be interviewed);

·   Preference for VHR & VP Scheme instead;

·   Expectations of residents;

·   Visual impact concerns.

·   Environmental impacts of Wilks Park Excavation;

·   Procurement of local materials/ contractors;

·   Space constraints for increased footprint and easement allowances;

·   Eligibility of houses to be raised;

·   Interim access routes and detours so residents can access their properties during road upgrade;

·   Internal drainage pumps/gates.

Financial

Other

·   Capital and ongoing costs of constructing and maintaining levee;

·   Cost of environmental assessment for the Wilks Park Excavation;

·   Cost of compensatory works;

·   Cost of Hampden Avenue upgrade;

·   Cap on VHR and VHP;

·   VHR/VP funding scheme ratio;

·   Time & resources for planning and assessment;

·   Benefits/Damage reduction.

·   Residual Flood Risk: Significant community education required to promote awareness of:

o Levee will be overtopped in events greater than a 5% AEP

o Levees can fail in a number of ways, at any time

o Dangers of sheltering in place instead of evacuating (isolation, long duration of inundation

·   Third party impacts

 

 

VHR and VP

Social

Construction and Implementation

·      Appetite for scheme, likelihood of participation:

·      Preference for levee option L4B instead

·      Expectations of residents

·      Number of properties eligible

·      Prioritization of eligible properties

·      Visual impact concerns

·      Procurement of local materials/contractors

·      Types of dwellings eligible for raising

·      Method of raising – piers or second story

·      Interim accommodation or assistance to residents during house raising

Financial

Other

·      Costs to raise a house;

·      Retrospective subsidy available for those who have already raised their houses above the FPL;

·      Co-contribution from OEH, Council, residents;

·      Time & resources for planning and assessment;

·    Benefits/ Property Damage reduction.

·      Flood immunity of key access routes and if road upgrades should be considered;

·      Community education regarding responsibility to evacuate;

·      Rules for appropriate use of ground floor (if not pier construction);

·      Overall timeframe of scheme and future participation;

·      Consideration of participation by subsequent property owners;

·    Residual flood risk and dangers of sheltering in place instead of evacuating (isolation, long duration of inundation

 

 

 

What is out of Scope for the project?

Any floodplain analysis, recommendations or actions outside of the North Wagga Village area and its connection by road to the CBD.

 

What constrains the way the project will be delivered?

The recommendation from the FRMAC is as follows and limits the project to this work:

 

To undertake a feasibility study for a North Wagga Levee with a 5% AEP level of protection WITH an equivalent upgrade to Hampden Avenue and conveyance improvements through Wilks Park, in conjunction with, Voluntary House Raising and Voluntary House Purchase Scheme in the Study Area which will assess the feasibility of a Voluntary House Raising and Voluntary Purchase Scheme in eligible areas of the Wagga Wagga Study Area.

 

What assumptions have been made about the project (on currently available information)?

<Explaining text here about assumptions made as to how the project will progress and deliver outcomes>

 

Describe how (if applicable) previous Lessons Learned from similar projects have been reviewed and applied for this project:

<Where a similar project (or part of the project) has been undertaken by Council before, make sure that this has been reviewed to capture and apply any relevant ‘lessons learned’.

 

Are there any related projects or other dependencies?

Main City Levee construction and the associated Flood studies as listed below:

 

In 1977, a desktop flood study was perfomed by Sinclair Knight based upon the 1974 flood event.

In May 1988, Waga Wagga Flood Study Report was prepared by NSW Department of Water Resources

In 2004, WMAwater produced and Council adopted a Flood Study based upon a 1D Tulfow model, calibrated to the 1974 flood event.

In 2009, Council adopted the Wagga Wagga Floodplain Risk Management Plan.

In 2010, WMAwater converted the 2004 model to a 2D TUFLOW flood model for Council.

In 2012, WMAwater produced a coarse 2D TUFLOW model for the entrire floodplain within the Local Government Area.

In 2013/14, Council, through WMAwater, revised its 2010 flood model to accomodate the revised rating tables for the Murrumbidgee River and validated and calibrated the model using survey and mapping data obtained following the 2010 and 2012 flood events, as well as a comparision to the 1974 flood event.

In 2018, Council, through WMAwater, adopted its Wagga Wagga Revised Floodplain Risk Management Study and Plan.

 

 

 

What is the total estimated project cost or Delivery Program budget allocation?

$234,000.00 excl GST (2:1 grant from OEH, $156K and $78K)

 

What is the total estimated effort hours for Council staff on this project?

Wagga Wagga City Council is well resourced and has prepared a dedicated project manager to undertake this project. Council's project management methodologies and processes will assist in carrying out the proposed project efficiently. Council also has a long history of carrying out and completing projects under the Floodplain Management Program and the Natural Disaster Resilience Grants Scheme.

 

 

 

Is this project clearly allowed for in the Delivery Program?

 

 

Yes:  If the Project is clearly allowed for – List the appropriate project category below. Complete a Business Case when this Project Brief is approved by Business Owner.

 

<Cost Centre and Code>, <Budget $>, <Financial year 200_ / 200_>

 

No: Complete a Business Case when this Project Brief is approved by Business Owner.

What is the expected timeframe to complete project?

<high level estimate here as to when the project is likely to start and finish>

 

 

What level of Consultation will be required during the Project?

 

Staff            active project participation

Community           Survey required

 

GO/NO GO decision to proceed to Planning Phase

Authorisation to proceed with Planning - Is the fundamental project concept and scope sound?

 

Business Owner Name and Position

Decision

Approved – may proceed to Planning Phase,

Pending - hold,

Denied – no further project action

Signature

(May also be noted as approved via email)

Decision date

<First Name, Surname>

 

 

 

 


 

 

 

Version Control

 

Version number

Purpose / Changes

Author

Date

1

Add Risk Identification table

K Holbrook

December 2017

2

Reformatted

K Holbrook

February 2018

3

Added ‘Organizational Involvement’

K Holbrook

March 2018

4

 

 

 

5

 

 

 

6

 

 

 

 


Report submitted to the Floodplain Risk Management Advisory Committee on Tuesday 18 June 2019.                                                         RP-1

 

  


Report submitted to the Floodplain Risk Management Advisory Committee on Tuesday 18 June 2019.

 

QUESTIONS WITH NOTICE 

 


Reports submitted to the Floodplain Risk Management Advisory Committee to be held on Tuesday 18 June 2019.