Results of Test-Hole Drilling in Well-Field Areas North of Tampa, Florida

A total of 32 test holes were drilled in well-field areas of Hillsborough, Pasco, and Pinellas Counties in the early 1970's to collect information on the hydraulic and geologic properties of shallow formations overlying the Upper Floridan aquifer. Lithologic profiles were compiled and geohydrologic units identified for each test hole. At most test holes, natural-gamma logs were run to identify the confining unit that separates the surficial aquifer system from the Upper Floridan aquifer. Selected core samples were analyzed in the laboratory for vertical hydraulic conductivity, grain size, sorting, specific gravity, effective porosity, cation-exchange capacity, and mineralogy. Following drilling, casing was installed in each test hole and water levels were monitored. The data were used in the preparation of regional water-level maps and in the construction of a numerical model of ground-water flow in the well-field areas.