Highway runoff in areas of karst topography

Karst terrain is characterized by sinkholes, depressions, caves, and underground drainage, generally underlain by soluble rocks such as limestone and dolomite. Because natural filtration through soil is limited in karst areas, pollutants in highway stormwater runoff can directly infiltrate underground sources of drinking water and environments that are habitats for sensitive species. Although the Virginia Department of Transportation (VDOT) has implemented guidelines for construction projects in karst areas to ameliorate this problem, there has been considerable activity at the state level in recent years concerning the protection of karst groundwater. New regulations or requirements regarding karst area runoff could add significantly to VDOT's construction and maintenance activities. This report summarizes the research and regulations to position VDOT to manage karst topography issues appropriately. Although more studies of karst groundwater contamination are needed, the literature does not currently support the need for more stringent regulatory controls than are already in place.