Perimeter Sand Filter Design Features
Located at the perimeter of parking lots
Developed originally in Delaware
Two parallel trench chambers
Two foot wet pool pretreatment
Ideal for small, highly impervious areas
Ideal for flat areas with relatively low available head.
Notes:
The Perimeter or �Delaware� sand filter, developed in part by Earl Shaver, consists of two parallel trench-like chambers that are typically installed along the perimeter of a parking lot. Parking lot runoff enters the first chamber which has a shallow permanent pool of water. The first trench provides pretreatment before the runoff spills into the second trench, which consists of an 12 inch deep sand layer. During a storm event, runoff is temporarily ponded above the normal pool and sand layer, respectively. The runoff is filtered through the sand, and collected by underdrains and delivered to a protected outflow point. When both chambers reach their flow capacity, excess parking lot runoff is routed to a bypass drop inlet.