Slide 12 of 52
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.