The Dover Street bioretention swale and detention basin were constructed in 2009 to manage stormwater runoff quality and local flooding associated with a new four hectare residential subdivision located immediately adjacent to the high value native vegetation of the Aldinga Scrub.
Stormwater runoff from the residential catchment is split into two pathways. Low flows are pre-treated via a gross pollutant trap, and high flows sheet flow along a grassed swale after which both sources discharge into the bioretention swale at its eastern end. The vegetated biofiltration swale is lined to ensure moisture is sustained to the plants during Adelaide’s summer dry spells. Five 100 mm slotted PVC pipes are located within a 200 mm deep layer of fine (5 mm screening) gravel. This drainage layer is covered with 100 mm of course sand and topped with a sandy loam filter media 300 mm deep. Stormwater discharges to a 2000 mm x 1000 mm grated inlet pit to the west, before flowing into a detention basin via a 675 mm concrete pipe and grated inlet overflow pit, protected from scour by an apron of geotextile fabric overlain with 300 mm rock. Overflow from the detention basin discharges into an underground tank, prior to being pumped to Hart Wetland, contributing to City of Onkaparinga’s stormwater re-use scheme
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