Recently, there has been an increased interest in the use of infiltration as a method of managing stormwater. Infiltration practices promote groundwater recharge, reduce runoff peak flows and volumes, and can lessen the transport of non-point source pollutants to surface water bodies. However, because stormwater infiltration systems are designed to discharge runoff into the soil, there has been concern that pollutants present in stormwater could contaminate groundwater wells. Thus, to understand the relative risks and benefits of infiltration, the fate of stormwater pollutants must be well understood. The fate of contaminants infiltrated from stormwater runoff and the potential for groundwater contamination was investigated by reviewing literature published in peer-reviewed scientific and engineering journals. This review examines common stormwater infiltration techniques, priority pollutants in urban stormwater runoff, and investigates the fate of these pollutants after infiltration. Priority pollutants in urban stormwater runoff include nutrients (i.e. nitrogen and phosphorus), heavy metals (i.e. Pb, Zn, Cu, Cd), organics (e.g. petroleum hydrocarbons), pathogens, suspended solids, and salts. The potential for groundwater contamination is a complex function of soil and contaminant properties and the depth to the water table. Karst geology in particular can provide pathways for rapid and extensive groundwater contamination from infiltration systems.
|Published - Jun 2008