Survey of Blasting Effects on Ground Water Supplies in Appalachia: Volume I

摘要

This report presents the results of a survey on blasting effects on ground water supplies in Appalachia. Literature was searched and cases of alleged water well damage were investigated. Occurrence of ground water in Appalachia is primarily in low yield, fractured, water table aquifers. Four test sites were chosen based on geographic and geologic diversity and wells were drilled at each site. Base line data on water quality, static water level, and drawdown characteristics were obtained before surface mining commenced. Blast-induced ground vibrations were measured at the surface at levels up to 5.44 inches per second maximum resultant particle velocity. Measurements made at the bottom of the wells indicated that vibrations were considerably attenuated at depths of 140 to 160 feet. No direct evidence of change in water quality or well performance was produced by blast vibrations, but removal of downslope support by excavation does cause lateral stress relief which permits the water-bearing fractures to become more open. This additional storage capacity causes the static water level to drop and for wellbore permeability to improve. Static water level recovers if sufficient recharge is available and well performance is improved.