ON-SITE DETENTION

This project required the installation of a 50 cubic metre detention tank under a driveway at a villa development in Sydney.

Extra Duty EnviroModules (4 braces in each) were used and surrounded in geotextile and Canvaccon Liner. The tank was backfilled with washed river sand to a depth of 200-400 mm above the tanks surface. A 150mm re-enforced concrete driveway slab was then placed over the tanks surface to evenly distribute loadings and allow cars and light utilities to traffic above.

Downpipes from the villas were connected to 3 discharge control pits that contained trash screens to prevent sediment and debris from entering the tank.

The tank was installed with a 1% fall to a discharge control pit at one end. This pit houses the orifice plate enabling the tank to empty to stormwater mains following each rain event.