AWWA CSC95041

Four communities (Western Heights, New Holland Borough, Blue Ball, and Terre Hill Borough, located in Lancaster County, Pennsylvania) are developing Wellhead Protection Programs to manage changing land uses and urban development to protect groundwater resources. Results of fracture trace analysis, combined with mathematical groundwater modeling, was used to develop a Wellhead Protection Area (WHPA) delineation technique for fractured-rock geology. The study area encompasses 80 square miles within Earl and East Earl Townships and is located within the most agriculturally productive, non-irrigated county in the United States. Initial WHPAs and protection zones were delineated for the community water supply wells and wellfields based upon recommended guidelines from the US Environmental Protection Agency (EPA) Region III and the Pennsylvania Department of Environmental Resources (PA DER). The following delineation criteria and methods apply: Zone 1: the 400-foot fixed radius; Zone 2: the area included within the 10-year time-of-travel capture zone determined by EPA's WHPA Model Version 2.0; and, Zone 3: the zone of contribution inferred from hydrogeologic mapping (surface water and groundwater divides, as well as aquifer outcrop areas). These initial WHPAs were then modified based upon a vulnerability mapping procedure which expanded the Zone 3 protection areas based upon interpretation of fracture trace analysis. This methodology was further refined into a semi-analytical modeling technique (SAMTECH) for delineation of WHPAs in fractured-rock aquifers.