Catchment Area: Balgownie, Fernhill, Fairy Meadow, Towradgi, Mount Pleasant, Mount Ousley, North Wollongong, Keiraville, West Wollongong and Gwynneville.
This catchment has experienced a number of major floods, the most recent in August 1998 which resulted in extensive damage to both public and private property. For sometime we have been working with the community and government agencies to reduce the social and economic impact of flooding in this catchment.
Flood risk planning
In 2010, a Flood Study, Floodplain Risk Management Study and Floodplain Risk Management Plan were completed for this catchment area. These studies were jointly funded by Council and the NSW State Government.
The Flood Study identifies the nature of the flood risk in the catchment area. The Floodplain Risk Management Study identifies the impacts of flooding on the community and measures to reduce flood risk.
The Floodplain Risk Management Plan outlines measures to best address the existing, future and continuing flood problems in the area and provide guidelines for all future developments in the area. Links to the reports are provided below.
Snapshot of flood risk and flood damages
The average annual damage within the study area is about $10 million. This is a measure of the cost of flood damage that could be expected each year on average by the community.
A 20 per cent Average Exceedance Probability [AEP] flood is expected cause damages of $10 million and flood 14 houses and 15 businesses above floor level.
A one per cent AEP flood is expected cause damages of $94 million and flood 599 houses and 206 businesses above floor level.
Implementation of mitigation measures
Prior to 2010 there were a number of flood mitigation measures that had already been implemented in the catchment which continue to be maintained.
Since 2010 Council and other agencies such as RMS have been working on the measures identified in the floodplain risk management plan. Below is a PDF of the works we have been working on.
Status of Implementation
Nine Debris Control Structures [DCS] have been built (some by RMS) and more than six are in design or ready to be constructed.
The study identified 16 DCS in addition to the existing three structures. Of these, two were not achievable. You can view the status of the DCS here.
McMahons Street detention Basin
Design and works for this project have been identified in Council’s Capital Works Program.
The current Floodplain Risk Management Study shows that a basin in this location has a significant benefit to reducing downstream flood levels. This has been confirmed by further detailed modelling. We've engaged a consultant to develop a concept design.
Keiraville Public School floodway
The current Floodplain Risk Management Study shows that this project could reduce downstream flood levels. However the potential impacts on the school and environmental constraints need to be further investigated to assess the feasibility of this project.
Hopewood Crescent Culvert upgrade
This project is currently on hold.
The current Floodplain Risk Management Study shows that this project could reduce downstream flood levels. However implementation would require at least three property acquisitions.
This project is not deemed viable at this stage and has not been included in the Capital Works Program.
Dawson Street Culvert upgrade
Design and works for this project has been identified in Council’s Capital Works Program.
This project includes upgrading the existing culverts to completely convey the 20% AEP flood, as well as realigning the creek within the upstream private property and some widening and scour protection at the downstream end of the new culvert. In addition to the culvert works, there is a need for bollards on the downstream side of Dawson Street and road depth indicators, to enhance public safety during flooding.
The benefits relate mainly to increased safety and reduced frequency of lost access to properties serviced by this important secondary traffic route from New Mt Pleasant Road to the Princes Highway.
Council has purchased 14 properties in the Fairy and Cabbage Tree Creeks catchment following the August 1998 flood.
Under the Fairy Cabbage Floodplain Risk Management Plan (FRMP), 49 dwellings (in 24 buildings since many are units) are earmarked for voluntary purchase. Since 2010, five dwellings have been purchased by Council.
Flood Study review
In October 2017, Council began a review of the Flood Study to provide greater detail of flood behaviour in the catchment. The more detailed modelling will take into account a better quality ground level survey, updated development information and Council's revised Conduit Blockage factors.
The review findings will be used to update technical data relating to the nature and extent of flooding in the catchment and will guide the subsequent review of the Floodplain Risk Management Study and Plan (2010). The review of the Flood Study will be overseen by a Floodplain Risk Management Committee which includes representatives from community groups and State agencies.
Have your say
If you have any information on past floods that you have not yet provided to Council, could you send to Council via email or mail to: Wollongong City Council, Locked Bag 8821, Wollongong DC NSW 2500