A momentous decision some 6 years in the making was made at the City Strategy & Policy Committee meeting last night.
The Unley Council has joined Burnside, Adelaide and Mitcham Councils in accepting the 80% two part strategy worked out recently by our collective CEO’s. The City of West Torrens is apparently siting down to consider their decision tonight.
The Chief Executive Officers of the five catchment Councils prepared a two-part strategy that will support the adoption of the Stormwater Management Plan by the Stormwater Management Authority and allow the delivery of stormwater mitigations outcomes for all catchment communities. The Stormwater Management Authority have indicated in principle that they recognise the benefit of proceeding along the lines suggested.
The proposed Strategy presents a significant opportunity to deliver four key outcomes for all catchment communities:
1. Committing the councils to commence flood mitigation works (Part A Works)
2. Agreement on cost apportionment between the councils.
3. Presenting a strong case and united front to the Commonwealth Government for funding support.
4. Pursuit of a ‘no dams’ solution; subject to its feasibility and community acceptance across all Councils (Part B Works).
This last point is not a lay down misere. The no dam solution may have significant impact across Unley (both social and financial) and both the dam and the non-dam option will be investigated over a 12-month period, following final acceptance of this approach by the Stormwater Management Authority and subsequent.
Our acceptance is conditional on a number of issues that relate directly to Unley, and these are:
I. Unley Road: A short section of old twin cell culvert structure pipe under Unley Road remains incomplete. This section has an approximate 5 year ARI capacity and will continue to cause overflow into Culvert Street and Unley Road during heavy storm events.
II. In addition to (I) construction of a short section of 1200mm diameter drain in Culvert Street to augment the capacity of the existing culvert immediately upstream of Unley Road should be supported in the plan.
III. Windsor Street: Further work is required to confirm that the Windsor Street section has sufficient capacity to accept the proposed flow of 12 m³/s (100 ARI) from the Fisher Street bypass culvert. This also raises the possibility that the plan might need to account for installation of further capacity on the Windsor Street section (through to the northern end of Henry Codd Reserve).
IV. Private Ownership: Sections along the Brownhill and Keswick Creeks have always provided a number of challenges when it comes to providing a clean creek system free of weeds, tree growing in the water course and modified banks in private ownership. It is vital for the success of the Brownhill Keswick Creek Draft Stormwater Management Plan, that the responsibility of maintaining a private section of creek be effectively managed, monitored and enforced. At this point in time it is unclear how this will be managed.
V. Open Space: It is suggested that further investigation be undertaken and consideration given to exploring the possibility of the culvert and diversion systems currently proposed being moved to align with the Brownhill Creek. An example of where this would be possible is Wilberforce Walk in Forestville which would create linear open space system.
VI. Flood Mapping: Updated flood plain maps need to be provided to the Councils for use by the planning areas.
VII. King William Road: The Council believes further assessment of the capacity of the King William Road culverts and the immediate downstream creek (generally privately owned) is also required during the development of the Stormwater Management Plan ‘Part B’ considerations.