USGS Groundwater Information: Hydrogeophysics Branch
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Peter K. Joesten, U.S. Geological Survey, Storrs, CT
John W. Lane, Jr., U.S. Geological Survey, Storrs, CT
Jennifer G. Savoie, U.S. Geological Survey, Northborough, MA
Roelof J. Versteeg, Columbia University, New York, NY
A pilot-scale study was conducted at the Massachusetts Military Reservation, Cape Cod, Massachusetts, to assess the use of a hydraulic-fracturing method to create vertical permeable walls of zero-valent iron to remediate ground water contaminated with chlorinated solvents at depths exceeding the range of conventional iron-wall installation methods. At the test site, ground-water contamination extends from 24 to 37 meters (m) below land surface. A treatment zone consisting of two parallel reactive-iron walls 12 m long, 13 m high, and 0.15 m thick, separated by about 6 m, was designed to intersect and remediate a portion of the CS-10 plume. The U.S. Geological Survey used a cross-hole, common-depth radar scanning method to test the continuity and estimate the lateral and vertical extent of the two reactive-iron walls. The cross-hole radar surveys were conducted in boreholes on opposite sides of the iron injection zones. Significant decreases in the amplitude of the radar pulse observed in scans traversing the injection zones were interpreted by comparing radar field data to results of two-dimensional, finite-difference, time-domain models and laboratory-scale physical models developed to predict the effects of wall edges and discontinuities on common-depth cross-hole radar measurements. As part of a feasibility study, single-hole radar reflection data was used successfully to image the walls.
Final copy as submitted to Symposium on the Application of Geophysics to Engineering and Environmental Problems for publication as: Joesten, P.K., Lane, J.W., Jr., Savoie, J.G., and Versteeg, R.J., 2001, Application of borehole-radar methods to image two permeable reactive-iron walls at the Massachusetts Millitary Reservation, Cape Cod, Massachusetts: in Symposium on the Application of Geophysics to Engineering and Environmental Problems, Denver, Colorado, March 4-7, 2001, Proceedings: Wheat Ridge, Colo., Environmental and Engineering Geophysical Society, CD-ROM.
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