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2•0 SUMMARY OF FIELD ACTIVITIES <br /> 21 Geophysical Survey <br /> As part of the subsurface investigation, a geophysical survey was performed on June 29, <br /> 1994 and directed by CEMI Project Geologist Larry Harlan The geophysical survey <br /> was performed by Spectrum Geophysics of Fremont, California Magnetic, <br /> electromagnetic, radio-frequency detectors, and ground-penetrating radar (GPR) <br /> techniques were employed to accurately identify and trace the orientation and location of <br /> the UST's and site utilities adjacent to the work area The geophysical survey identified <br /> the location and orientation of UST "B" and a three-feet diameter man hole access-way <br /> 1P was lifted for observation of this UST The access-way "collar" is constructed of brick <br /> and the two-foot diameter tank access-way and tank was observed to be constructed of <br /> steel Depth to the top of the tank was measured at three (3) feet below ground surface <br /> (bgs) and the depth to the bottom of tank was measured at approximately nine (9) feet <br /> bgs Approximately three feet of water, with a slight sheen, was observed in the bottom <br /> of the tank and there appeared to be no free product stored in the UST at this time <br /> UST "A" was not detected with the above mentioned geophysical techniques During <br /> the field work, and following the geophysical survey, GSA representative Chris Holmer <br /> notified CEMI that he had observed a depression in the grass surface several months <br /> prior to this investigation and near the public sidewalk Upon further investigation <br /> K084023 RPT <br />