Abstract
Extensive karst conditions have been known in the Hershey Valley since 1949 when large numbers of catastrophic sink holes developed in response to extreme lowering of the ground water surface by pumping at a mining operation. During and subsequent to that time extensive geologic mapping has documented the dynamic character of karst and the extent and severity of its formation in the valley.
Many large structures have been erected in the Hershey Valley during the past fifteen years in response to a rapidly growing community. Foundation conditions have varied but, in every case, have revealed widespread karst conditions, characterized by pinnacle weathering and cavernous rock, undrained depressions and Sinkholes.
Geologic investigations have been a fundamental requirement for developing safe foundations. Evaluation of the geology at four of the many recently constructed buildings in the Hershey Valley provides the basis for comparing different approaches to foundation design. Caissons were used at the Hershey Medical Center and Hershey Convention Center; steel piling was used at a large fuel oil storage tank facility; spread footings in conjunction with special surface and underground drainage design were employed at the Hershey Foods Tour Facility. In each case the choice of foundation design was dictated by the specific geologic conditions at the site.
