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 alterations to parking lot designs can dramatically decrease runoff and pollutant loads. Three paving surfaces are compared, as well as basins with and without swales, to measure pollutant concentrations and infiltration. Preliminary results from the first year of a 2-year study indicate that swales reduce 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 rain is found to be a significant input for inorganic nitrogen. Other water quality 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 detected in the sediments in all basins, but concentrations were higher in basins paved with asphalt and some values approached toxic levels. Pesticides were also detected in the sediments, especially the banned organo-chlorine pesticide, dichloro-diphenyl-trichloroethane, and its daughter products.