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OEOMATRIX <br /> A total of six groundwater monitoring wells are used to monitor groundwater quality beneath the <br /> site Groundwater samples were collected by WGR from six groundwater monitoring wells <br /> (MW3-1, MW3-2, MW3-3, MW3-4, MW3-5, and MW3-6) On February 24, 2005, monitoring <br />' wells MW3-1, MW3-2, MW3-3, MW3-4, MW3-5, and MW3-6 (Figure 2) were purged and <br /> sampled by WGR Depth to groundwater was measured in the site monitoring wells before <br /> purging Prior to sampling each well, the presence of separate-phase petroleum hydrocarbon was <br /> assessed with a disposable bailer Groundwater was purged from each well using dedicated <br /> submersible pumps Each dedicated submersible pump is uniquely identified for use in the same <br />' well each quarter and is stored on site <br /> Each well was purged of at least three well volumes Field parameters were measured after . <br /> purging approximately each well volume Field parameters consisted of electrical conductivity, <br /> pH, temperature, dissolved oxygen, and oxidation reduction potential and were recorded on field <br /> data sheets (Appendix A) Dissolved oxygen readings during the first quarter 2005 indicated <br /> dissolved oxygen concentrations greater than saturation A problem with the dissolved oxygen <br /> meter has been corrected (WGR, personal communication) After purging was complete and the <br /> dedicated pumps were removed from the monitoring wells, new clean disposable bailers were <br /> used to collect groundwater samples from the monitoring wells The groundwater samples were <br /> transferred from the bailers into sample containers The samples were collected for laboratory <br /> analysis of total petroleum hydrocarbons quantified as gasoline (TPHg) and benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) <br />' 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 8015Cm and SW8260B, <br />' respectively <br /> 3.0 MONITORING RESULTS <br /> First quarter 2005 WGR monitoring results are discussed in the following sections <br />' 3.1 GROUNDWATER ELEVATION, FLOW DIRECTION,AND GRADIENTS <br /> Groundwater elevation data from February 24, 2005 (Table 1), were used to construct <br /> potentiometnc contours on Figure 3 No separate-phase petroleum hydrocarbons were reported <br /> in the site wells Groundwater levels have risen 2 52 to 2 83 feet in the site monitoring wells <br /> I <br /> 16000x16437 0001Archtve16437-027 doc 2 <br />