USE OF VEGETATIVE CONTROLS FOR TREATMENT OF HIGHWAY RUNOFF

Abstract

Pollutants found in runoff from highways may cause toxic responses in receiving waters for some conditions and, in addition, are obstacles to obtaining water quality goals in the United States. This study investigated the capability of two vegetative controls -- grassed swales and vegetated buffer strips -- to treat highway runoff. A grassed swale was constructed in an outdoor channel to investigate the impacts of swale length, water depth, and season of the year on removal efficiency. Results indicate that swale length and water depth affect the removal of runoff constituents by swales, and that the removal efficiency can vary with the season of the year. Two vegetated strips treating highway runoff in the Austin, Texas, area were monitored to determine removal capabilities. The filter strips removed most constituents effectively and consistently, and the inclusion of filter strips is recommended in future highway design if conditions are appropriate and right-of-way is available.