Common types of water-bearing features in bedrock, Rockdale County, Georgia

Until recently, little was known about the specific types of water-bearing features or “zones” tapped by deep production wells in the crystalline igneous and metamorphic bedrock of the Piedmont physiographic province of Georgia (Fig. 1). Detailed study of the depth, nature, and yield of water-bearing features in Rockdale County, Georgia, indicates that foliation-parallel parting planes, sheet fractures, joints, and weathered veins are among the most common. An optical televiewer and other borehole-geophysical logging tools were used to delineate water-bearing features in 20 “open-hole” bedrock wells located in various parts of the study area (Fig. 1). Flow-meter measurements were used to determine the depth and yield of water-bearing zones in each well. Geologic map-ping was used to correlate water-bearing features with various lithologic units in the area.Sponsored by: Georgia Environmental Protection Division U.S. Geological Survey, Georgia Water Science Center U.S. Department of Agriculture, Natural Resources Conservation Service Georgia Institute of Technology, Georgia Water Resources Institute The University of Georgia, Water Resources Facult