Research of Hydrologic and Water Quality Performance of 4 Linear Wetlands in Eastern North Carolina

The North Carolina Department of Transportation is charged by an agreement with the North Carolina Department of Environment and Natural Resources to treat stormwater from NC DOT facilities across North Carolina. One heretofore unaccounted treatment is hundreds of miles of right-of-way swales in eastern North Carolina. It is possible that these serendipitous practices are improving runoff quality along theses highways. If so, an assessment of their performance is needed. Four existing right-of-way linear swales along I–40 east of I–95 will be monitored to determine their hydrologic and water quality effectiveness. Two different treatments are being examined: one swale that is unaltered and one that has been allowed to establish wetland conditions. There are two examples of each. Monitoring will also address the impact of the vegetated filter strip between the shoulder and the edge of the swale. Monitoring began in August of 2008. Samples are being collected from 18 events and analyzed for TN, TKN, NH₄—N, NO_2–3—N, TP, and TSS.