Surface-geophysical investigation of a formerly used defense site, Machiasport, Maine, February 2003
Surface-geophysical surveys were conducted in February 2003 at a formerly used defense site in Maine, where residual chlorinated solvents are affecting off-site domestic water-supply wells. The U.S. Geological Survey and Argonne National Laboratory used surface-geophysical methods, including ground-penetrating radar and seismic-refraction tomography, to characterize the lithology and structure of the bedrock at the site and to identify highly fractured areas that may provide pathways for ground-water flow and contaminant transport. Multifrequency electromagnetic and inductive terrain-conductivity methods also were evaluated, but these techniques were adversely affected by a nearby naval computer and telecommunications station.
Interpretation of the data from ground-penetrating radar indicates that depth to the weathered bedrock surface is approximately 0.5 to 3 meters. Reflections from within the bedrock are visible throughout all ground-penetrating radar profiles, and zones of scattered electromagnetic energy may correlate to zones of highly fractured bedrock. Interpretation of the data from seismic-refraction tomography inversion indicates that zones of relatively low seismic velocity and topographic lows may correlate with fractured and water-producing intervals within the bedrock. Integrated interpretation of the results from ground-penetrating radar and seismic-refraction tomography was used to locate boreholes along the surface-geophysical profiles. An integrated analysis of information obtained from the surface- and borehole-geophysical surveys and test drilling will be used by the U.S. Army Corps of Engineers to develop a conceptual model of ground-water flow and solute transport at the site.
Citation Information
Publication Year | 2005 |
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Title | Surface-geophysical investigation of a formerly used defense site, Machiasport, Maine, February 2003 |
DOI | 10.3133/sir20045099 |
Authors | Eric A. White |
Publication Type | Report |
Publication Subtype | USGS Numbered Series |
Series Title | Scientific Investigations Report |
Series Number | 2004-5099 |
Index ID | sir20045099 |
Record Source | USGS Publications Warehouse |
USGS Organization | Office of Ground Water |