Date of this Version
Report # SPR-1(09) P325 Final Report 26-1120-0043-001
Stormwater from roadways could have negative effects on the environment and aquatic ecosystems. Typical highway runoff pollutants include solids; heavy metals, particularly cadmium, copper, and zinc; petroleum hydrocarbons; gasoline constituents; PAHs (polyaromatic hydrocarbons); oxygen demanding compounds measured as COD (chemical oxygen demand) and BOD (biochemical oxygen demand); and road salts. Roadway runoff falls under the legislation of the Clean Water Act (CWA) via the National Pollutant Discharge Elimination System (NPDES). CWA regulates discharge of nonpoint source pollutants, such as roadway runoff, by issuing permits to public entities which manage Municipal Separate Storm Sewer Systems (MS4s). Part of the Nebraska Department of Roads (NDOR) permitting requirement is to create a design guide for Best Management Practices (BMPs) tailored to remediate roadway runoff in Nebraska. The objectives of volume I of this research were to characterize the pollutants in roadway runoff and determine the effectiveness of the existing stormwater BMPs at the study site. To accomplish these objectives, eleven rainfall events were sampled from November 2008 through November 2010. First flush and composite highway runoff samples were analyzed for heavy metals, anions, nutrients, particulates, BOD, COD, VOCs, and SVOCs. In addition to the concentrations, event loads were calculated using the hydrologic information from the study site. The results were compared to the Nebraska standards for water quality to establish which contaminants could have a negative impact on the environment. Additionally, an assessment of the effectiveness of the existing detention basin was completed, using the pollutant loads from the different outlet pipes.