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A controlled release of tetrachloroethylene was performed in a saturated, natural sandy aquifer to evaluate the effectiveness of various geophysical techniques for detecting and monitoring dense nonaqueous phase liquids (DNAPLs) in the subsurface. Tetrachloroethylene, typical of most DNAPLs, has a low relative dielectric permittivity (2.3), which contrasts with the high relative permittivity (80) of the pore water it displaces, making it a potential target for detection by ground‐penetrating radar (GPR). GPR data were acquired using 200 MHz antennas. Radar sections collected at different times over the same spatial location clearly show the changes induced by the movement of DNAPL in the subsurface. Temporal changes can be examined through the evolution of a radar data trace collected at a single spatial location. Normal moveout analysis of common‐midpoint (CMP) data demonstrates induced changes in …