Public Works Committee: Lower Brownhill Creek Capacity Upgrades

Mr BROWN (Florey) (11:55): I move:

That the 56^th report of the committee, entitled Lower Brownhill Creek Capacity Upgrades, be noted.

The Brownhill Keswick Creek catchment area is approximately 70 square kilometres and incorporates significant portions of the south-eastern, inner-southern and south-western suburbs of Adelaide, within the local government areas of Adelaide, Burnside, Mitcham, Unley and West Torrens. The catchment comprises four significant watercourses, namely, Brownhill Creek, Keswick Creek, Glen Osmond Creek and Park Lands Creek. They are crucial drainage watercourses in metropolitan Adelaide that flow into the Patawalonga River.

The Stormwater Management Authority (SMA) proposes to double the flow capacity of a section of Lower Brownhill Creek, which forms part of broader suite of flood mitigation works and measures identified through a 2016 management plan for the affected local government areas. This plan proposes a series of works collectively referred to as the Brownhill Keswick Creek Stormwater Project, with the main aim being to mitigate significant flood risk and help safeguard properties from the four major watercourses in the catchment.

This catchment has a history of flooding, and a low standard of flood protection has been the subject of numerous studies and investigations over several decades. Whilst a major flood event has not occurred since 1930, the lower portion of Brownhill Creek, located in the south-western suburbs of Adelaide, is at a great risk of flooding. The proposed upgrade will consist of works to 3.3 kilometres of the Brownhill Creek channel, beginning at Anzac Highway at Ashford and ending at the south-eastern corner of the Adelaide Airport.

The channel is primarily situated within a 12-metre wide drainage reserve on land owned by the City of West Torrens, and comprises sections of earthen and concrete lining. The capital cost of the project is $56 million, and construction has commenced and is scheduled to occur over a seven-year period.

The Stormwater Management Plan for the catchment represents a culmination of complex and protracted negotiations between the catchment councils and proposes a series of works and measures, including wetlands and detention basins, channel improvements, and culvert and bridge upgrades. The project works will be within council-owned drainage reserves, with some sections encroaching and intersecting upon privately-owned land, which involves existing concrete channels through residential properties.

Completion of these capacity upgrade works, along with subsequent stages of the Brownhill Keswick Creek Stormwater Project, will provide flood protection to over 3,900 properties, including critical services, such as Ashford Hospital and the South Australian Ambulance Service. The project will also protect critical transport infrastructure, including the north-south corridor, interstate rail lines and the Adelaide Airport. The key aims of the upgrade are to:

mitigate the impacts of flooding, including in the occurrence of a one in 100-year flood event;

improve the quality of stormwater run-off to meet targets set in the Adelaide Coastal Waters Quality Improvement Plan;

maximise the beneficial reuse of stormwater;

protect and enhance riparian ecosystems;

ensure effective land use planning outcomes; and

promote sustainable asset management of stormwater infrastructure.

The successful delivery of the Lower Brownhill Creek upgrades will utilise the principle of working progressively in an upstream direction to ensure the downstream reaches of the creek system can cater for the increased water capacity.

To facilitate this, the upgrades have been categorised into a series of 10 work packages, starting at Netley and finishing at Ashford. The Brownhill Keswick Creek Stormwater Board will be both the major client and the principal in the project management delivery. The project director will provide the SMA with regular status reports through all stages of the project.

The SMA has incorporated sustainable development principles into the scope of the project, and optimising whole-of-life costs and environmental impacts have been a key focus in the design process. Active design strategies have been employed to incorporate a naturalised channel solution through areas of public open space.

Extensive consultation and engagement are ongoing and a reference group has been established to inform the design of the channel upgrades in open spaces, which is inclusive of input from Kaurna traditional owners. It should be pointed out that the Attorney-General's Department has determined that there are no registered or reported Aboriginal sites, objects or ancestral remains within the project area.

The committee examined written and oral evidence in relation to the Lower Brownhill Creek Capacity Upgrades project. Many witnesses appeared before the committee, and I would like to thank them all now collectively for their time. I would also like to take this opportunity to thank the member for Badcoe for her statement to the committee supporting this important project in her electorate. Based upon the evidence considered and pursuant to section12C of the Parliamentary Committees Act 1991, the Public Works Committee reports to parliament that it recommends the proposed pubic work.

Motion carried.