Geophysical Methods to Site High Capacity Water Wells

Several aquifers have uneven and unpredictable distribution of permeability.  The yield of a well in these aquifers will vary substantially depending on its location.  This has made it difficult to drill high capacity wells in many fracture dominated aquifers, many glacial aquifers, and several sandstone aquifers.  Some other aquifers can contain pockets of salty or brackish water.  The vertical and lateral distribution of the zones of poor water quality is often hard to predict without drilling and sampling.  These problems have plagued wells in coastal areas, deep basins with old water, and in areas with road salt contamination.

Several geophysical methods have been developed that can map the distribution of sand bodies, fractures, and other permeable features from the surface.  Other methods can detect salty or brackish water zones.  These methods can be used to screen large areas to find the best places to drill or monitor changes in water quality around a well during its pumping life.

This presentation will present several surface geophysical methods that can be used to map permeable units or water quality to depths of less than 100 feet to over 1,000 feet.  Recent advances in equipment and data processing have improved the resolution and reliability of these methods making them a useful tool in difficult aquifers.  Several case histories in a variety of geologic environments will be presented.