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Detailed Design

Brandy & Water Creek- Investigation & Design of Creek Modification

Introduction

Cardno undertook a Floodplain Risk Management Study and Plan (FRMSP) for the Allans Creek catchment in 2006 on behalf of Wollongong City Council (Council). The Allans Creek Catchment has a total area of approximately 42 square kilometres, and extends from the Illawarra Escarpment in the west to the Port Kembla Inner Harbour in the east. This FRMSP investigated a variety of structural and non-structural flood management options to reduce flood damage and risk, and prepared a Flood Risk Management Plan for Council to manage the existing, future and continuing flood risks. One of the flooding areas identified by the Allans Creek FRMSP is along Brandy and Water Creek in the vicinity of the Darragh Drive, Figtree. This area is shown in Figure 1.1. This FRMSP identified a number of residential properties on the east bank (left bank) of Brandy and Water Creek which experience overfloor flooding in the 1% AEP. The FRMSP recommended a further investigation of options to potentially decrease the overfloor flood risk. One of the options is to lower the west bank (right bank) of the creek opposite these residential properties to increase conveyance and alleviate the potential overfloor flooding as a result. Cardno was commissioned by Council in 2013 to undertake a further investigation into the creek modification option recommended by Allans Creek FRMSP in this area, and identify the final location and the detailed information regarding the creek modification works. In addition, this project brief included preparation of a concept design suitable for preliminary benefit-cost analysis and community consultation.

1.1 Study Objectives

This study intends to achieve the following objectives: · Investigate the flood behaviour under the existing conditions by incorporating the additional ground survey data;

  • Investigate the flood management options recommended in the Allans Creek FRMSP;
  • Undertake an assessment of options to ensure the proposed creek works are consistent with the works proposed in the Allans Creek Catchment Riparian Management Plan (Forbes Rigby, 2002), and maximise the hydraulic and economic benefits.
  • Evaluate the restrictions related to the proposed works aimed at reducing the social, environmental and economic impacts of flooding over a range of potential flood events, including 1% AEP, 2% AEP, 5% AEP, 10% AEP, 20% AEP, and the Probable Maximum Flood (PMF);
  • Provide a concept design suitable for preliminary benefit-cost analysis and community consultation, and;
  • Make a recommendation to Council based on a Multi-criteria assessment. 1.2 Report Outline In order to achieve the objectives above, the report is outlined as follows:
  • Data Inputs (Section 1.3);
  • Site Investigation (Section 2);
  • Flood Behaviour under the Current Existing Conditions (Section 3);
  • Damage Assessment (Section 4);
  • Floodplain Risk Management Options (Section 5); and
  • Economic Assessment of Flood Modification Measures (Section 6).

Additional Information

Field Value
Title Brandy & Water Creek- Investigation & Design of Creek Modification
Publication Date 1 May 2014
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Author/ Prepared by Cardno (NSW/ACT) Pty Ltd
Publish date 7 July 2017
Update date 26 July 2017
Place Name Brandy Creek , Water Creek
Approval State Approved
Submitted for approval 7 July 2017
Submitted by Jamin Hudson
Approved 27 July 2017
Approved by plattns
Data Comment

Report only.

Identifier 471a06cf-1786-494c-8c14-f1835f7b1e19