POLLUTANT ATTENUATION STUDY IN A HIGHWAY RUNOFF DETENTION BASIN AT SHREVEPORT, LOUISIANA

The Louisiana Department of Transportation and Development (LA DOTD) constructed a concrete lined detention basin to receive and hold the runoff from a 2-mile long interstate highway bridge at Shreveport, Louisiana. This paper discusses the performance of the basin in attenuating bridge runoff pollutants for a majority of the storms in the year 1998. Total suspended solids (TSS) and chemical oxygen demand (COD) were the two major constituents in the bridge runoff. Other constituents, (total phosphorus, ammonia-N and nitrate-N) were present in low concentrations. The basin primarily acted as a settling basin and was most effective in terms of TSS removal. For other constituents, the basin exhibited a somewhat erratic range of removal efficiencies, but it was still able to reduce their concentrations in most cases.