Managing flood risks in the Collins Creek catchment

POSSIBLE measures that could help reduce flood risks to people, property, and infrastructure in known “hot spots” in the Collins Creek Catchment area are under investigation by Wollongong City Council.

This piece of work builds on Council’s previous Collins Creek Floodplain Risk Management Study project, which was informed by community feedback in 2014. It also responds to the works Council has done to mitigate flood risk and uses new data and more advanced computer modelling and methods for estimating flood levels and future flood mitigation works.

The proposed projects will require analysis and planning to inform future infrastructure delivery programs.

Residents have until Monday March 25 2024 to take a look at the reviewed Collins Creek Floodplain Risk Management Study and Plan, participate in a community information session and share their feedback.

Wollongong Lord Mayor Gordon Bradbery said that the City of Wollongong is naturally flood prone, and Council’s focus is on flood risk mitigation through both proactive research and a comprehensive program of works.

“Thanks to our location, living between the mountains and sea, we’re naturally prone to experiencing flash flooding,” he said.

“Over the years, we’ve taken a proactive approach to managing flood risk by planning ahead. This means regularly updating our flood risk management studies and plans as we receive new data and improvements to computer modelling and methods for estimating floods.

“Then we’re able to use this information to deliver on-the-ground improvements like detention basins and stormwater infrastructure. Right now, we’re taking a fresh look at the Collins Creek Catchment. We’ve suggested a number of potential measures that could improve flood risk and we’re now seeking community feedback from people living in Bulli, Woonona, Russell Vale, and Bellambi.”

What’s being proposed?

To help people visualise Council’s plans, see the study area map on Council’s website. This map shows the locations of the recommended measures:

• WC3 Hospital Rd culvert trash rack, Bulli – This trash rack will catch debris before it enters the culvert, preventing blockages that raise water levels upstream and increase the risk of flooding of downstream properties. It will be designed to let water flow freely while trapping large debris.
• FC1 Hollymount Park channel upgrade, Woonona – The existing channel on the southern side of Hollymount Park will be expanded and the stormwater inlet alongside it would be improved. This should allow it to carry more water, reducing the risk of it overflowing and flooding nearby properties on Kathleen Crescent.
• BG1 Princes Hwy detention basin, Russell Vale – Upgrades to the existing flood detention area to raise the walls of the basin so it can hold more water. The culvert under the highway will be adjusted to reduce the rate of water flow from the basin through downstream properties.
• FC3 Memorial Dr & York Rd culvert upgrade, Russell Vale – Two culverts under York Road will be upgraded and the creek channel beneath Memorial Drive regraded so it slopes down toward the waterways east of Memorial Drive and west of the railway line.

Council is also proposing several other long-term options that will help to manage flood risk:

• Development controls to ensure future development is appropriate for flood-affected land
• General community education
• Make property flood level information available.
• Emergency response plans for flood-affected homes and businesses to ensure residents and business owners know what to do in the event of a flood
• Updates to the Illawarra Flood Emergency Sub Plans
• Voluntary house raising or purchase for eligible properties
• Flood warning systems.
• Vegetation management plans for nominated sections of creeks in public ownership
• Develop an interim Entrance Management Policy for Collins Creek and Bellambi Lake catchments, to manage the height of the sand berms located at their outlets.

“We’ve prepared a number of different flood management options that we believe will help reduce the impacts of future floods,” Cr Bradbery said.

“Flood management is not just the responsibility of Council; we need our residents to get on board by being aware of their flood risk, how that risk can be managed and how they can take preventive action. It’s also important for people to understand that some of the areas that may be affected by flooding aren’t always on Council owned or managed land and that private landowners also have a responsibility when it comes to reducing the impact of flooding.”

“Please take the time to review these plans and get involved in the discussions. We know that local lived experience is valuable information, and we want to hear from our community so that we can ensure our studies and plans are the best they can be.”

Drop-in information session

Council representatives and consulting engineers who have been working on the Floodplain Risk Management Study and Plan for this catchment will be available ay a drop-in information session at the Bulli Senior Citizens Centre, 8 Hospital Road, Bulli on Wednesday March 6, anytime between 3.30pm and 630pm. There will be maps showing the location of recommended measures for managing flood risk. There’s no need to book, just drop-in at any time during the session.

For more information, visit the Our Wollongong website, email Council, call Council’s customer service line on (02) 4227 7111 or write to: The Engagement Team, Locked Bag 8821, Wollongong DC 2500.

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