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FIRST QUARTER,1997 <br /> GROUNDWATER MONITORING REPORT <br /> ' USA STATION#65-LODI <br /> FEBRUARY, 1997 <br /> 3 0 SCOPE OF WORK <br /> Groundwater monitoring was completed at the site on January 23, 1997 The following is a brief <br /> ' summary of the scope of work authorized by USA <br /> ® Located and measured depths to groundwater in monitoring wells MW_I through <br /> MW-8, S-1 and S-2, <br /> • Purged a muumum of three equivalent well volumes of groundwater from each of <br /> ' the sampled wells, monitor pH, temperature and conductivity, <br /> Collected groundwater samples from the purged monitoring wells, <br /> ° Analyzed water samples for TPH in ther asoline <br /> ether g ange (TPH G), methyl-tert-butyl- <br /> (MTBE) and BTEX, using EPA Methods 8015 Modified and 8020, <br /> ' respectively, and <br /> ° Prepared this QMR for submittal to USA and the County <br /> M' <br /> 4.0 GROUNDWATER MONITORING <br /> The following section discusses field <br /> protocol used during data collection for this QMR <br /> ' 4.1 Groundwater Elevations <br /> Upon gauging depths to groundwater, the groundwater monitoring wells were checked for the <br />' presence of free floating hydrocarbon using an interface probe Depths to groundwater <br /> measurements were then taken from each well from surveyed marks on the casing using an <br /> electric water Ievel sensor or interface probe Calculated groundwater elevations are presented in <br /> Table I The field data sheets are included in Appendix A <br /> t4.2 Monitonng Well Purging <br /> The monitoring wells were purged using a 2-inch diameter submersible Grundfos groundwater <br />' pump or disposable bailer, until a minimum of three equivalent well volumes of water were <br /> removed from each well Groundwater purged from the wells was placed into Department of <br /> Transportation (DOT) approved 55-gallon drums and stored on-site prior to disposal by USA <br /> To reduce the potential for cross-contamination between <br /> ing <br /> equipment was washed in a trisodium phosphate solutiion and l rinsed in potable ws, all Purging and ater or to each <br /> usage p <br /> 3 <br />