ANALYTIC ELEMENT MODELING FOR SOURCE WATER ASSESSMENTS OF PUBLIC WATER SUPPLY WELLS: CASE STUDIES IN GLACIAL OUTWASH AND THE BASIN AND RANGE

Over the last 10 years the EPA has invested in analytic elements as a computational method used in public domain software supporting capture zone delineation for source water assessments and wellhead protection. The current release is called WhAEM2000 (wellhead analytic element model). The program provides an interactive computer environment for design of protection areas based on radius methods, well in uniform flow solutions, and geohydrologic modeling using analytic elements. Protection areas are interactively designed and using electronic maps based on the US Geological Survey Digital Line Graph (DLG). Geohydrologic modeling for steady pumping wells, including the influence of hydrological boundaries, such as rivers, recharge, no-flow boundaries, and inhomogeneity zones, is accomplished using the analytic element method. Reverse gradient tracelines emanating from the pumping center of known residence time are used to delineate the capture zones. Two case studies will be presented: the Vincennes, IN wellfield located in glacial outwash; and the Salt Lake City, UT wellfield located in the basin and range.