USE OF OVERLAND FLOW IN STORM-WATER MANAGEMENT ON INTERSTATE HIGHWAYS

An assessment of the potential of shallow-water ditches and shoulder areas adjacent to roadways for deposition of heavy metals is reported. The metals examined in the field were those that result from automobile emissions and the wear of automotive parts: lead, zinc, copper, chromium, and nickel. Cadmium content was also measured. The highest concentrations of metals were found in roadside plant and animal populations. These, however, contained the least metals in mass. Soils adjacent to the edge of the pavement contained the greatest mass of metals. In general, the topsoil contained higher concentrations of metals than subsurface soils. Lead was shown to be relatively immobilized by the soil, whereas other metals were more mobile. Design equations for estimating the volume of shallow-water storage areas for rainfall excess (runoff) are presented. In general, the use of overland flow with shallow ditch areas was shown to be effective for the control of runoff and its associated pollution content. (Author)