Ground water pollution potential of Butler County, Ohio

Includes bibliographical references (pages 22-25)A ground water pollution potential map of Butler County has been prepared using the DRASTIC mapping process. The DRASTIC system consists of two major elements: the designation of mappable units, termed hydrogeologic settings, and the superposition of a relative rating system for pollution potential. Hydrogeologic settings incorporate the major hydrogeologic factors that control ground water movement and occurrence, including depth to water, net recharge, aquifer media, soil media, topography, impact of the vadose zone media, and hydraulic conductivity of the aquifer. The relative ranking scheme uses a combination of weights and ratings to produce a numerical value called the pollution potential index that helps prioritize areas with respect to ground water contamination vulnerability. Hydrogeologic settings and the corresponding pollution potential indexes are displayed graphically on maps. Butler County lies within the Glaciated Central hydrogeologic region. The county is covered by variable thicknesses of glacial till, moraines, river alluvium, and outwash deposits in buried valleys. These unconsolidated deposits are underlain by shale and shaley limestone bedrock that is capable of supplying only small quantities of ground water. Pollution potential indexes are relatively low to moderate in areas of till cover over bedrock, and moderate in areas covered by glacial moraines. Areas of river alluvium with overbank deposits exhibit a moderate vulnerability to contamination. Buried valleys containing sand and gravel aquifers have moderate to high vulnerabilities to contamination. Four hydrogeologic settings were identified in Butler County with computed ground water pollution potential indexes ranging from 79 to 211. The ground water pollution potential map of Butler County was prepared to assist planners, managers, and local officials in evaluating the potential for contamination from various sources of pollution. This information can be used to help direct resources and land-use activities to appropriate areas, or to assist in protection, monitoring, and cleanup effort