Low-impact parking lot design reduces runoff and pollutant loads

An innovative parking lot at the Florida Aquarium in Tampa, Fla., is beings used as a research site and demonstration project to show how small altera tions to parking lot designs can dramatically decrease runoff and pollutant loads. Three paving surfaces are compared, as well as basins with and with out swales, to measure pollutant concentrations and infiltration. Prelimina ry results from the first year of a 2-year study indicate that swales reduc e average runoff amounts by 30% at this site and pervious paving reduces it by an additional 10-15%. Rainfall water quality was also evaluated, and ra in is found to be a significant input for inorganic nitrogen. Other water q uality data show higher phosphorus concentrations in basins with vegetated swales and higher metal concentrations in basins paved with asphalt rather than cement or pervious paving. Polycyclic aromatic hydrocarbons were detec ted in the sediments in all basins, but concentrations were higher in basin s paved with asphalt and some values approached toxic levels. Pesticides we re also detected in the sediments, especially the banned organo-chlorine pe sticide, dichloro-diphenyl-trichloroethane, and its daughter products.