The City of South Perth turned an unsightly open drain into an attractive grassed reserve by installing an underground stormwater detention system constructed from Rocla® reinforced concrete box culverts.
The shallow drain at the bottom of a hill was causing flooding problems on adjacent properties in the upmarket riverside area, prompting the council to build the underground holding tank.
The system has a capacity of more than 1500 cubic metres and is designed to cope with a 1 in 50 year flood.
Rocla in Perth supplied 98 large box culverts (3600 x 2100) and 49 link slabs to construction contractor Mako Civil to build the huge three-cell detention tank, which is fed by stormwater pipes from two adjacent roads.
Unlike most on-site detention tanks, the box culverts are not inverted to create an impervious base.
The culvert legs stand on concrete footings but the base of the tank is a 200mm layer of crushed concrete aggregate that allows the stormwater to infiltrate into Perth’s sandy soil.