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L. Piezometer Installation and Destruction <br /> City of n RWCF <br /> Page 3 <br /> L Field activities were conducted under the supervision of a California Professional Geologist. Drill <br /> cuttings for the temporary piezometer boring were logged in accordance with the Unified Soil <br /> Classification System (USCS). Soil cuttings were spread in the vicinity of each piezometer location. <br /> ` Piezometer construction graphics are included as part of the geologic log for each temporary piezometer <br /> (Attachment B). <br /> Depth to groundwater measurements below top of casing were recorded for each piezometer following <br /> installation and are provided in Table 2,below. <br /> Table 2 -Depth to Groundwater(August 17, 2007) <br /> Screened Groundwater <br /> Piezometer ID Interval (b s Depth Below <br /> g ) To of Casin <br /> PZ-1 11 - 16 14.18 <br /> PZ-2 11-16 12.82 <br /> PZ-3 15-20 17.38 <br /> PZ-4 15-20 17.32 <br /> Notes: All measurements are in feet;bgs=below ground surface <br /> Top of casing is approximately 2.5 feet above ground surface <br /> Piezometer Casing Survey <br /> ` Condor representatives surveyed the locations of the four newly installed piezometers on August 20, <br /> 2007. The horizontal positions of the piezometers were referenced to NAD83 horizontal datum with an <br /> accuracy of 0.3 feet and the vertical positions were referenced to NAVD88 vertical datum with an <br /> accuracy of 0.01 feet. Piezometer elevations were measured on the north edge of each piezometer. Survey <br /> 6. coordinates and piezometer elevations are shown in Table 3,below and in Attachment C. <br /> Table 3-Piezometer Survey Details (August 20,2007) <br /> Piezometer ID Longitude X(Fasting) Latitude Y(Northing) Z(Elevation)* <br /> PZ-1 -121.3364 6320454.09 37.9380 2165111.49 15.28 <br /> PZ-2 -121.3386 6319812.16 37.9386 2165312.93 15.10 <br /> PZ-3 -121.3391 6319678.43 37.9379 2165077.38 14.84 <br /> PZ-4 -121.3370 6320260.56 37.9377 2164984.85 16.03 <br /> Note: *Z(Elevation)=top of piezometer casing elevation <br /> Piezometer Destructions <br /> 6. Following completion of the 14-day g oundwater gradient study, a permit to destroy the piezometers was <br /> obtained from the SJCEHD and the four temporary piezometers were destroyed in accordance with <br /> SJCEHD requirements. A Condor representative was on-site on March 13, 2008 to supervise the <br /> 6. destruction of the four piezometers. Each piezometer was destroyed by lifting the PVC casing and <br /> dislodging the slip cap from the bottom of the screen. Volclay® bentonite grout was pumped into each <br /> boring using the piezometer casing as tremie pipe as it was retracted. The grout was mixed in accordance <br /> It. to manufacturer's recommendations. The borings were backfilled with grout to approximately one-foot <br /> below grade, and finished to surface with native material.The piezometer destructions were performed by <br /> L V &W; Mr. Girardi with SJCEHD observed the destructions. A copy of the SJCEHD destruction permit <br /> is included in Attachment D. <br /> L <br /> w <br /> A�W_ <br /> `ss L IL41 CONDOR <br />