What is the Ursula Road Scheme?

    The Combined Catchment of Whartons, Collins and Farrahars Creeks, Bellambi Gully and Bellambi Lake Floodplain Risk Management Study and Plan was prepared in 2014. It identified a range of measures that could potentially better manage the flood risk in each catchment. It showed that one of the problem areas is located between Franklin Avenue and Trinity Row at Bulli, within the Whartons Creek catchment. Several measures, collectively referred to as the “Ursula Road Flood Mitigation Scheme”, were recommended for further investigation to address the flood problem. These included:

    • Measure WC02 – expansion of the existing flood retarding basin near Gordon Hutton Park
    • Measure WC06 – construction of a flood deflection levee on the northern bank of Whartons Creek, immediately upstream of Franklin Avenue
    • Measure WC07 – upgrade the existing Franklin Avenue culverts (tunnel/drain structure under the road) and increase the waterway area for the downstream channel
    • Measure WC09 – drainage upgrades along Ursula Road and Trinity Row at the eastern end of Ursula Road

    Further investigations were then completed in 2017. The outcomes of this determined that measure WC02 should not proceed to more detailed investigations due to low benefit-cost ratio, lack of community support and potential safety risk to neighbouring buildings. Measures WC06, WC07 and WC09 were recommended for further investigation. 

    What work has been done since you last spoke to the community about the Scheme?

    The current investigation builds on the previous studies to provide a better understanding of the feasibility of each measure, i.e. how practical, successful or effective they might be. This included:

    • hydraulic flood modelling to measure how each one performs in a flood
    • preparation of concept design plans for each measure
    • an economic assessment to work out the potential costs and reduction in flood damages that each measure may provide

    This information helps us decide which measure, or combination of measures, should move forward to the next stage, called ‘detailed design’.

    Which Scheme is recommended?

    Each measure was assessed individually and WC06 had the best overall economic and hydraulic performance. WC07 and WC09 also offered some small reductions in flood levels across areas that were not benefited by WC06. Some combinations of measures were then assessed. The best overall economic and hydraulic reductions in flood levels and above-floor flooding across a range of flood sizes is predicted to occur using this combination of measures:

    • WC06 - construction of levee at Franklin Ave. Two small levees on the southern side of Spinners Way and at the rear of two Benelong Street properties were added to mitigate adverse flood impacts from the Franklin Ave levee
    • WC09A - Trinity Row overland flow path 
    • WC09E - levee along eastern property boundary of Bulli High School 

    It is recommended that the future detailed design phase be staged in this order of priority:

    • High Priority: Franklin Avenue, Spinners Way and Benelong Street levees
    • Medium Priority: Trinity Row overland flow path
    • Low Priority: Bulli High School levee

    The assigned priorities were based on the respective flood benefits provided by each measure relative to their cost (benefit-cost ratio).

    The proposed levees (or parts of) at Franklin Ave, Benelong St and Bulli High would need to be built on land not owned by Council. The affected landowners at these locations would need to be supportive before we could proceed to detailed design for these measures.

    The Draft Concept Design Report details the outcomes of the concept design phase, including the investigation of various options. 

    How will the proposed Scheme benefit my property?

    The proposed flood mitigation scheme generally results in an improvement in flooding across a large area between Franklin Avenue and Trinity Row. Decreases in existing flood level of up to 0.3m are common, and fewer properties are exposed to above-floor flooding. There are 12 fewer properties in a 1% AEP (annual exceedance probability) event, meaning there is a 1% chance of a flood of this size occurring at this location in any given year. There are 21 fewer properties in a PMF (probable maximum flood) event - the largest flood likely to ever occur.

    Will any properties experience increased flood impacts from the proposed Scheme?

    The Scheme will result in some small local increases in flood levels over Franklin Avenue and Farrell Road, within the railway corridor and Bulli High School. It is proposed that flood warning signage be installed at these two road locations. The small increases in flood levels within the railway corridor are not predicted to result in more frequent overtopping of the railway tracks, while the increases within the school are contained to a small portion of the sporting fields/open space and are not predicted to impact any building floor levels.

    What happens next?

    Subject to support from landowners, the next stage will involve development of the detailed design. Detailed design is where we gather more information to further refine the concept and create plans, specifications and cost estimates. This will confirm the technical, hydraulic and economic feasibility of the measure/s to demonstrate their effectiveness and whether it is worth the investment.  If so, it can then proceed to the final stage, construction.

    Is climate change considered during these investigations?

    Yes, the impact of climate change (increase in rainfall intensity and sea levels) was considered. The results show that the Scheme performs similarly under both climate change conditions and current climate conditions.

    Would clearing Whartons Creek help?

    Our investigations found that removal of vegetation from the creek would have very little impact on reducing flood levels in the area. We are focusing our resources on investigating those measures that our studies show have the most potential for providing a significant reduction in flood levels. We have a maintenance program for creeks on Council-owned land, however, most watercourses in our city are on private property and their maintenance is the responsibility of the landowner.

    How will my feedback be used?

    At the end of the engagement period, all feedback is read and considered. Council’s Floodplain & Stormwater team will use this feedback to make changes to the concept and/or detailed design schedule if needed.

    How can I join the conversation?

    To book a time to attend either the online or in-person session, phone (02) 4227 7238 or email C&CSAdmin@wollongong.nsw.gov.au