Hydraulic logging methods—a summary of field methods used in fractured bedrock systems, Georgia
Johnson, Carole D.
Williams, John H.
Williams, Lester J.
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Hydraulic logging methods provide impor-tant information for groundwater investigations being con-ducted in areas underlain by fractured bedrock systems. Geophysical surveying techniques are used to delineate and characterize hydraulically active zones, delineate the extent of contamination and contaminant sources, identify geo-logic features, optimize monitoring well placement, and guide remediation efforts. Borehole-geophysical methods provide information about physical, chemical, and hydrau-lic properties of rock, sediments, and fluids in the subsur-face and provide important information on subsurface bed-rock structures including lithology, rock fabric, location, orientation, and hydraulic properties of fractures. Effective use of geophysical data requires that the data be interpreted in the context of known local and regional geology and hydrogeology. In addition, because of the complexity and heterogeneity of crystalline-rock aquifers, a suite of bore-hole-geophysical methods is used to determine the location, extent, and nature of fractures and other structural features in the bedrock aquifer. The geophysical data from each borehole are analyzed together to provide an integrated interpretation, thereby reducing the ambiguity that can occur by interpreting each geophysical log individually.