Pervious pavement / porous pavement consists of a permeable surface course underlain by a uniformly-graded stone bed. Stormwater drains through the surface, is temporarily held in the voids of the stone bed, and then slowly drains into the underlying, uncompacted soil mantle. The Morris Arboretum, in Philadelphia, PA, has successfully integrated this BMP into its parking areas to control rainwater runoff and help improve water quality in the local creek