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GEOMATAIX <br /> A total of six groundwater monitoring wells are used to monitor groundwater quality below the <br /> site. Groundwater samples were collected by WGR from five groundwater monitoring wells <br /> (MW3-1, MW3-2, MW34, MW3-5, and MW3-6). As during the previous three quarters, well <br /> MW3-3 could not be, sampled because it was covered with soil forming a portion of a temporary <br /> equipment access ramp. The ramp was.constructed for equipment used to refurbish two <br /> anhydrous ammonia storage tanks at a nearby facility(see WGR letter in Geomatrix, 2004). On <br /> September 23, 2004, wells MW3-1, MW3-2, MW34, MW3-5, and MW3-6 (Figure 2) were <br /> purged and sampled by WGR. Depth to groundwater was measured in the site monitoring wells <br /> before purging. Prior to sampling each well, the presence of separate-phase petroleum <br /> hydrocarbon was assessed with a disposable bailer. About 20 to 28 gallons of water were purged <br /> from each well using dedicated submersible pumps. Each dedicated submersible pump is <br /> r�.. uniquely identified for use in the same well each quarter and is stored on site. <br /> Each well was purged in two phases of about 10 gallons each. Field parameters were measured <br /> near the conclusion of each pumping phase. Field parameters consisted of electric conductivity, <br /> pH, temperature, dissolved oxygen, and oxidation reduction potential and were recorded on field <br /> data sheets (Appendix A). After purging was complete and the dedicated pumps were removed <br /> from the monitoring wells, new clean disposable bailers were used to collect groundwater <br /> samples from the monitoring wells. The groundwater samples were transferred from the bailers <br /> into sample containers. The samples were collected for laboratory analysis of total petroleum <br /> hydrocarbons quantified as gasoline (TPHg) and benzene, toluene, ethylbenzene, and xylenes <br /> (BTEX). <br /> `s Groundwater samples collected by WGR were preserved and transported under chain-of-custody <br /> (Appendix B) procedures to McCampbell Analytical, Inc. (MAI), in Pacheco, California, a <br /> state-certified laboratory. The groundwater samples were analyzed by MAI for TPHg.and BTEX <br /> using U.S. Environmental Protection Agency(EPA) methods SW8015Cm and 8260B, <br /> respectively. Although methyl tertiary-butyl ether(MTBE) is no longer a constituent of concern <br /> at UST Site No. 3, MAI inadvertently tested the samples for MTBE by Method SW8260B. <br /> ` Results are reported in the following section. <br /> 3.0 MONITORING RESULTS <br /> Third quarter 2004 WGR monitoring results are discussed in the following sections. <br /> I:\PRO]ECT16000s16437.000\6437-33.doe 2 <br />