McElhanney Consulting Services Ltd, specified this innovative SWM System for a commercial development in Langley. The system was installed in July 2005.
The Atlantis tank system installation consisted of a 770 m³ (27192 cf) detention tank installed under a parking lot. The underground detention system receives surface run-off through a network of catch basins connected to the tank by underground pipes. The system is designed to capture the stormwater from a one in one hundred year storm event. The depth of cover above the tank is 600 mm (23.6″) to substantiate H 20 Vehicle loading requirements.
Some of the collected storm water will ex-filtrate into the ground through the surrounding slightly permeable native soil. The remaining water will drain into the existing municipal storm sewers through a controlled outlet. By managing the storm water locally and delaying its release, this tank will prevent local flooding and stream erosion during heavy storms.