First flush

Abstract: Storm water runoff from urban roadways often contains significant quantities of metal elements and solids. These anthropogenic constituents are generated mainly from traffic-related activities. Metal elements partition into dissolved and particulate-bound fractions as a function of pH, pavement residence time, and solids concentration. Lateral pavement sheet flow from an experimental field site on a heavily traveled urban highway in Cincinnati was sampled during five rainfall runoff events in 1995. Results indicate that Zn, Cd, and Cu are mainly in dissolved form while Pb, Fe, and Al are mainly particulate-bound. Dissolved fractions of Zn, Cd, and Cu exhibited a strong first flush in lateral pavement sheet flow. Pb exhibited a weak first flush for all events. Event mean concentrations of Zn, Cd, and Cu exceed surface water quality discharge standards. Findings from this study will assist in the development of effective control strategies for the immobilization of metal elements and solids in urban runoff.

Abstract: MATERIALS WHICH COMMONLY RESIDE ON STREET SURFACES HAVE BEEN FOUND TO CONTRIBUTE SUBSTANTIALLY TO URBAN POLLUTION WHEN WASHED INTO RECEIVING WATERS BY STORM RUNOFF. CALCULATIONS BASED ON A HYPOTHETICAL BUT TYPICAL U. S. CITY INDICATED THAT THE RUNOFF FROM THE FIRST HOUR OF A MODERATE-TO-HEAVY STORM WOULD CONTRIBUTE CONSIDERABLY MORE POLLUTIONAL LOAD THAN WOULD THE SAME CITY'S SANITARY SEWAGE DURING THE SAME PERIOD OF TIME. THE STUDY PROVIDES A BASIS FOR EVALUATING THE SIGNIFICANCE OF THIS SOURCE OF WATER POLLUTION AND PROVIDES INFORMATION FOR COMMUNITIES HAVING A BROAD RANGE OF SIZES, GEOGRAPHICAL LOCALES, AND PUBLIC WORKS PRACTICES. INFORMATION WAS DEVELOPED FOR MAJOR LAND-USE AREAS WITHIN THE CITIES. THE ANALYSIS OF THE RUNOFF IS ALSO REPORTED. /AUTHOR/