Performance assessment of porous asphalt for stormwater treatment

Abstract

The objective of this study is to assess the stormwater management capability of porous asphalt (PA) as a parking lot in Durham, New Hampshire. The site was constructed in 2004 and consists of a 4-inch PA pavement course overlying a porous media reservoir, including a fine-grained filter course. Cost per PA parking space ($2,200) was comparable to that for dense mix asphalt ($2,000). Pavement durability has been adequate. The lot retained or infiltrated 25% of precipitation (18 months) and 0.03 lb/sf of chloride (1 year). There was high initial surface infiltration capacity (IC) at two locations (1,000--1,300 in/hr), and moderate IC at a third (330 in/hr). Two locations had a 50% decrease in IC. Frost penetration occurred to 1 foot. Storm event hydraulic performance was exceptional. Storm event water quality treatment for diesel, zinc, and TSS were excellent; for chloride and nitrate it was negative, and for phosphorus, limited.*