tribution of contaminants and velocity of groundwater flow, as well as for delineating subsurface geology. The depths of principal interest are 10-100 ft, with a maximum of about 300 ft. Among the most promising sensors for applications at hazardous waste sites are EM sondes, natural gamma loggers, fluid conductivity and temperature loggers, and thermal groundwater flow meters. Acknowledgment Much of the material in this article is attributable to the following publications: Benson, R. C. et al. "Geophysical Techniques for Sensing Buried Waste Migration," prepared under U.S. EPA Contract 68-03-3050; Publication 146, National Water Well Association: Worthington, Ohio, 1983. Walther, E. G. et al. "Study of Subsurface Contamination with Geophysical Monitoring Methods at Henderson, Nevada," In "Proceedings of the National Conference on Management of Uncontrolled Hazardous Waste Sites"; Hazardous Materials Control Research Institute: Silver Spring, Md., 1983. Before publication, this article was reviewed for suitability as an ES&T feature by A. Shane Hitchcock, U.S. EPA, Atlanta, Ga. 3036S, and Donald H. Bruehl, Normandeau Associates, Inc., Bedford, N.H. 03102.
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Environ. Sci. Technol., Vol. 18, No. 11,1984
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