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GROUNDWATER ASSESSMENT REPORT <br /> GROUNDWATER MONITORING WELL SURVEYING <br /> ' In February 2002, Morrow Surveying surveyed monitoring wells MW-1 through MW-4 for <br /> horizontal location and vertical elevation The survey results are presented in Table 5 A copy of <br /> the surveying report is attached as Appendix E The coordinates are California State Plane Zone <br /> 3 coordinates from GPS observations using University of California Bay Area Deformation Cors <br /> Station observation files and based on the California spatial reference center datum Elevations <br /> are based on Stockton benchmark No 20(elevation= 12 86 feet) <br /> TABLE 5 <br /> MONITORING WELL SURVEY DATA <br /> TOC <br /> Well Elevation Elevation <br /> Identification (msl) (Box) Northing Easting Latitude Longitude <br /> MW-1 650 673 21789503 63273266 37 9762352 -121 3130181 <br /> MW-2 597 618 21789337 63272740 37 9761884 -121 3131999 <br /> MW-3 604 623 21789290 6327311 3 37 9761763 -121 3130702 <br /> MW-4 601 615 21788723 63273275 37 9760210 -121 3130125 <br /> Notes TOC=Top of Casing <br /> msl=feet above mean sea level <br /> SOURCE Morrow Surveying,February 2002 <br /> r <br /> GROUNDWATER MONITORING AND SAMPLIN <br /> G <br /> As shown on Table 5,ESA monitored and sampled the four groundwater monitoring wells four <br /> times between January 2002 and April 2003 Prior to sampling,the depth to water in each well <br /> was recorded by an electronic well sounder and each well was purged of at least three volume <br /> casings of water using a peristaltic pump while monitoring pH, temperature and conductivity to <br /> ensure the presence of formation water Groundwater elevation data for each sampling event are <br /> provided in Table 6 The field monitoring parameters are provided in Appendix D Once the <br /> wells recharged to within approximately 80 percent of their initial volume,groundwater was <br /> sampled using an electric peristaltic pump equipped with dedicated, Teflon tubing The <br /> peristaltic pump was set on the lowest speed to reduce volatilization of compounds in the sample <br /> �-- -- —-- ,The groundwater samples were decanted into pre-cleaned glassware supplied by the laboratory, <br /> labeled and placed in cool storage prior to transportation to McCampbell Analytical <br /> Groundwater samples were analyzed by the laboratory for the presence of TPH as gasoline and <br /> BTEX by EPA Methods 8015 and 8020, and MTBE, DIPS,TAME, ETBE, EDB, 1-2 DCA, <br /> Groundwater Assessment Report 14 ESA/200252 <br /> September 2003 <br />