The Cities of Marion and Holdfast Bay have taken a coordinated approach to stormwater management planning as significant proportion of the Marion Catchment runs through the City of Holdfast Bay. Their catchments lying west of the Sturt River, draining to the coast cover a combined area of close to 35 km2.
The catchment area has been identified as experiencing significant growth over the next 30 years which will place additional strain on the existing drainage system. The stormwater management plan sets strategies, actions and programs for the Councils to become ‘water sensitive cities’.
Water quality improvement strategies for the catchment which address overall water quality targets for Adelaide, have been addressed in the plan. The built-up nature of the catchment, restricts space for typical water quality improvement devices such as wetlands, therefore innovative solutions were required.
The plan investigated how new EPA water quality improvement targets can be met in a highly urbanised catchment with largely impermeable soil types.
An investigation into how the 30 year plan for greater Adelaide can be implemented within the catchment was made considering current development trends are not in line with the plan.
On-site retention techniques were recommended for the catchment in line with the water quality and quantity targets set by the EPA.
Potential flooding was assessed with TuFlow two dimensional flood plain modelling. This modelled flows in the underground stormwater network as well as overland flows and storage in the catchment.
2013 IPWEA Excellence Award — the plan was considered best practice in stormwater management planning.