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32 Field Activities <br /> Geophysical Survey <br /> The geophysical fieldwork was performed by Geocon and involved attempting to locate a buried <br /> monitoring well (MW-14) with ground penetrating radar (GPR) GPR uses radar imaging to look for <br /> buried objects The GPR survey was conducted within a 5-meter by 5-meter paved area Cruz Brothers <br /> Locators provided utility location services in the vicinity of the MW-14 and the CPT borings Cruz <br />' Brothers used a Fisher/MScope Precision Metal Detector, a RD400 Radiodetection Precision Pipe and <br /> Cable Locator, and an RD500 Radiodetection Plastic Water Pipe locator Recorded anomalies were <br />' outlined on the ground surface with paint and subsequently field mapped A transite water pipe was <br /> reported to be buried in the proposed CPT boring area Cruz Brothers was unable to locate the transite <br /> pipe However,Geocon was able to locate the pipe using GPR <br /> t Geocon used a Geophysical Surve S stems Inc GSSI SIRS stem 8 GPR system with a GSSI <br /> Y Systems, (GSSI) Y <br />' Model 5103 400 megahertz antenna, and displayed GPR data on a video monitor attached to a GSSI <br /> Model 38 Video Display Unit As the GPR data was collected, it was recorded onto VHS format <br /> videotape for storage and review The instrument was calibrated to record over a 50-nanosecond (ns) <br /> vertical scale along each traverse Videotape records of each GPR profile were made and reviewed in <br /> the field for indications of the suspect buried monitoring well <br /> Field Ex loration <br />' Field exploration, monitoring well destruction and installation activities and the cone penetrometer <br /> testing were observed by a representative of IT Corporation <br /> Subsequent backhoe exploration was performed by Geocon to carefully excavate the area where <br /> monitoring well MW-14 was believed to be located based on the geophysical data A 3-meter(9-feet) <br /> by 3-meter (9-feet) section was explored using a backhoe to remove the asphalt concrete Below the <br /> asphalt concrete, approximately 0 9 meter (3-feet) of compacted fill was encountered underlain by a <br /> layer of filter fabric Continued exploration revealed the 10 16-centimeter(4-inch)polyvinyl chloride <br /> (PVC) well casing at a depth of approximately 1 2 meters (4-feet) The exposed well casing was <br />' protected and the excavation backfilled Sounding of the well revealed about 6 meters (20 feet) of <br /> material in the bottom of the well <br />' Monitoring Well Destruction and Installation <br /> Records provided by the SJCEHD indicated that monitoring well MW-14 had been constructed with <br /> a bentonite grout seal extending to near the ground surface Bentonite seals constructed in this <br /> Project No 58475-06-02 4- December 26,2001 <br />