WATER-QUALITY ASSESSMENT OF STORMWATER RUNOFF FROM A HEAVILY USED URBAN HIGHWAY BRIDGE IN MIAMI, FLORIDA

Runoff from a 1.43-acre bridge section of Interstate 95 in Miami, Florida, was monitored during five storms to estimate loads of selected water-quality parameters washed from this heavily traveled roadway. The monitoring was conducted periodically from November 1979 to May 1981 in cooperation with the Florida Department of Transportation for the specific purpose of quantifying the concentrations and loads of selected water-quality parameters in urban-roadway runoff. Automated instrumentation was used during each of the five storms to collect periodic samples of bridge runoff and to measure continuously the storm discharge from the bridge surface and the local rainfall. For most target parameters, 6 to 11 samples were collected for analyses during each event. Results of these analyses generally indicated that the parameter concentrations in the stormwater runoff and the parameter load magnitudes were quite variable among the five storms, although both were similar to the levels reported for numerous other roadway sites. Storm intensity influenced the rate of loading, but parameter concentration was the dominant variable controlling the overall magnitude of loading. (Author)