PROBLEMS ENCOUNTERED AND RECOMMENDATIONS MADE DURING A GROUND-WATER SURVEY WITHIN THE MARBURG SCHIST IN WEST MANHEIM TOWNSHIP, YORK COUNTY, PENNSYLVANIA

West Manheim Township (Township) is in southwestern York County, Pa., and is within the Piedmont Physiographic Province, Piedmont Uplands Section, where it is underlain predominantly (90 percent) by the Marburg Schist. Because of its proximity to major metropolitan centers, the Township faces rapid development and growth - an estimated 4,000 new homes are projected in the next 5 years. With only 30 percent of households using public supplies, much of the water needs must be met through private domestic wells. The availability of ground water in the Township, however, is uncertain. Homeowners commonly have described the need for drilling multiple wells before a suitable yield was established. To better evaluate the potential of the Marburg Schist to met projected water demands, the Township initiated a ground-water study in February 2005. As an initial step in the study, 422 well-driller cards and/or consultant reports from local, state, and Federal databases were examined. A total of 164 wells (39 percent) were determined to have satisfactory spatial coordinates of 0.1 to 2 seconds latitude and longitude (based on site visits, street addresses, parcel or lot numbers, and/or driller maps) to accurately plot the wells on existing digital (topography, geology) coverages. The remaining 258 wells could only be roughly located (3 to +30 seconds latitude and longitude or 200 to +3,000 feet) but were nevertheless assigned to the Marburg Schist because of the predominance of this aquifer in the Township. Although all 422 wells were used to evaluate the Marburg Schist, significant hydrogeologic information (for example: effects of topographic setting, lineaments, and lithology on yields; distribution of well yields; and depth to bedrock) could not be obtained from 60 percent of the examined databases. This lack of adequate data coverage thus prevented an adequate assessment of spatial variation or trends in well yield and specific capacity. As a result, several recommendations were presented to the Township to improve their collection of well data including (1) purchase and utilize a Global Positioning System to obtain proper spatial coordinate data for each well, (2) visit sites to obtain static water levels after well completion, (3) perform minimum 1-hour drawdown tests with measurement of discharge volume, and (4) develop an electronic database for well-driller records.