Culvert OSD provides quick fix for floods

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.