FAQs

We make computer models and maps that show where it could flood and by how much. From time to time, these models are reviewed and predicted levels may change. The reasons why can include:

• New floods occur, providing additional data to fine-tune the model.
• More advanced computer models or methods for estimating flood levels become available.
• Changes in the catchment, such as flood mitigation works or new developments.
• Changes in policy.

For this catchment, we updated the 2019 flood study to incorporate the new Australian Rainfall & Runoff (ARR2019) flood estimation guidelines. You can now access the updated Flood Study documents:

• Allans Creek Flood Study - ARR2019 Revision
• Allans Creek Flood Study Revision - Map Compendium:
  • Allans Creek Flood Study Map Compendium_Part 1
  • Allans Creek Flood Study Map Compendium_Part 2
  • Allans Creek Flood Study Map Compendium_Part 3
  • Allans Creek Flood Study Map Compendium_Part 4
  • Allans Creek Flood Study Map Compendium_Part 5
  • Allans Creek Flood Study Map Compendium_Part 6

After we update flood models, we also need to update our understanding of what the risks/damages from floods might be. We then need to update our plan for mitigating (reducing) these. This is what a floodplain risk management study and plan does. It has a prioritised plan of recommended measures to best address existing and future flood problems in the catchment. It also includes guidelines for all future developments in the area.

Installing more ‘debris control structures’ Debris control structures (DCS) are designed to protect culverts and bridges from becoming blocked. The FRMSP has recommended to install 3 new DCS across the catchment. This photo shows an example of a culvert and DCS:

We’ve looked at many options to better manage flood risk in the catchment, however some were not recommended to progress based on the assessments undertaken by the consultants and subject matter experts. You may still provide feedback on these, however. The options that were not recommended include:

Scheme A
Scheme A included:

• Widening Byarong Creek upstream of Princes Highway, Figtree (FM14); and
• Replacing The Avenue, Figtree culvert with a bridge (modified FM20) to reduce the adverse impact of FM14.

The cost of Scheme A outweighed the benefits and causes some negative flood impacts to properties.

FM60 – Upgrade culverts under Alukea Road, Cordeaux Heights
The option aims to upgrade the culverts under Alukea Road to allow more water to flow through. The upgraded culverts would be around twice as big the existing culverts.

This option provides only minor benefits with significant cost.

FM55 – Upgrade culverts under M1 Motorway
The option aims to upgrade the culverts under the M1 so they are less prone to blockage from tress, branches, rocks and litter. Eight smaller culverts would be replaced by four larger culverts.

The cost of this option outweighed the benefits.

We have historical flood level records and/or our completed flood studies for some properties, but not all. Please contact our Customer Service team on (02) 4227 7111 to find out what’s available for your property.

After we’ve completed the Floodplain Risk Management Study and Plan, more work will be done to develop concepts and detailed designs for the recommended stormwater structures. We’ll take these out to the community to seek further input before the designs are completed.

At the end of the engagement period, we read and consider all feedback. We write a report about the engagement and what we heard. It is provided to the project team and Central Floodplain Committee for consideration in making a decision.

• Online  www.our.wollongong.nsw.gov.au                           
• Email    engagement@wollongong.nsw.gov.au                                
• Write    Locked Bag 8821, Wollongong DC 2500                
• Phone   (02) 4227 7111                                      
• Drop-in Information Session (no presentation)
  When: Wednesday 13 September 2023 - drop in anytime between 3:30-6:30pm
  Where: Figtree Community Hall (West), 11 Princes Highway, Figtree      

If you’re d/Deaf or have a hearing or speech impairment, you can contact us through the National Relay Service. If you need an interpreter, you can contact us through the Translating and Interpreting Service on 131450. You’ll need to provide our phone number 02 4227 7111 for either service.