Surface-geophysical investigation of a formerly used defense site, Machiasport, Maine, February 2003

Scientific Investigations Report 2004-5099



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.

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Publication type Report
Publication Subtype USGS Numbered Series
Title Surface-geophysical investigation of a formerly used defense site, Machiasport, Maine, February 2003
Series title Scientific Investigations Report
Series number 2004-5099
DOI 10.3133/sir20045099
Year Published 2005
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Office of Ground Water
Description v, 48 p.
Country United States
State Maine
City Machiasport
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