A large gravel parking lot used for military vehicles and equipment at Camp Murray Military Base in Tillicum, Washington, was regularly overflowing onto adjacent property during large storm events. The Washington State Military Department Division of Facilities and Grounds needed a solution that followed stormwater management regulations as stated in the Washington State Department of Ecology’s Stormwater Management Manual for Western Washington (SWMM). A Stormwater Control System Corrective Design Plan was developed for Camp Murray in spring 2004 to recommend BMPs, including repairs, retrofits, and alternative designs for the existing stormwater control structures.
The Washington State Military Department wanted a high-tech stormwater pollutant removal system to trap and treat the stormwater runoff and help protect local water quality. Working with Shaw Environmental, Inc. – the engineering firm on the project – they chose a 13 cartridge Stormwater Management StormFilter vault to install beneath the parking lot where it would pretreat a significant portion of the runoff from the Camp. The StormFilter system is also approved by the Washington State Department of Ecology (WA DOE).
Downstream, a ChamberMaxx plastic retention system was installed in order to collect, retain and infiltrate the remaining runoff. With the StormFilter system located upstream, it reduces maintenance cost in the ChamberMaxx system and extends the performance life of the overall system. It will also be a successful solution to manage the future volumes that will occur when the parking lot is paved.
“The maintenance department is very happy that the Stormwater Management StormFilter vault was specified upstream of the ChamberMaxx infiltration system” said Brad Olson, Construction Manager with the Washington State Military Department. “They like the fact that they will be able to easily inspect and maintain the pretreatment system while extending the maintenance cycle on the infiltration system”