Assessment of potential groundwater contamination sources in a wellhead protection area

Determining the human health dangers from potential contamination sources, within a wellhead protection area (WHPA), requires that a risk analysis be undertaken. In this study, a desktop geographic information system and spre adsheet software are used to implement an EPA risk screening methodology fo r WHPAs called 'Managing Ground Wafer Contamination Sources in Wellhead Pro tection Areas-A Priority Setting Approach'. The methodology was applied to a WHPA in Gaston County, North Carolina. Results indicate that the risk of well contamination from an interstate highway and gas station with old stee l underground storage tanks were comparatively high, Medium risks included a thoroughfare and highway, while low risks were assigned to machine shops, a body shop, septic systems and a gas station with new underground storage tanks and secondary containment. A sensitivity analyses of the Priority Se tting Approach indicated that risk scores were extremely sensitive to hydro geologic variables such as hydraulic conductivity It is recommended that ri sk assessors utilize a range of hydrogeologic parameters to assess overall risk from each potential contamination source. (C) 2001 Academic Press.