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1 _ <br /> Geomatrix <br /> • A total of six groundwater monitoring;wells are used to momtor groundwater quality beneath the <br />' site On June 1, 2005,monitoring wells MW3-1, MW3-2, MW3-3, MW34, MW3-5, and <br /> MW3-6 (Figure 2) were purged and sampled by WGR Depth to groundwater was measured in <br /> the site monitoring wells before any of the wells were purged Prior to sampling each well, the <br /> presence of separate-phase petroleum hydrocarbon was assessed with a disposable bailer <br /> Groundwater was purged from each well using dedicated submersible pumps Each dedicated <br />' submersible pump is uniquely identified for use in the same well each quarter and is stored on <br /> site <br />' Field parameters were measured after r gaPproximatel each well volume Field <br />' parameters consisted of electrical conductivity, pH, temperature, dissolved oxygen, and <br /> oxidation reduction potential and were recorded on field data sheets (Appendix A) After <br />' purging was complete and the dedicated pumps were removed from the monitoring wells, new <br /> clean disposable bailers were used to collect groundwater samples from the monitoring wells <br /> The groundwater samples were transferred from the bailers into sample containers The samples <br />' were collected for laboratory analysis of total petroleum hydrocarbons quantified as gasoline <br /> (TPHg) and benzene, toluene, 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 SW8015Cm and SW8260B, <br />' respectively <br />' Examination of the purge forms indicated anomalous temperature and electrical conductivity <br /> readings Additionally, less than three casing volumes were removed from wells MW3-1, <br />' MW3-2, MW3-3, and MW3-5 prior to sampling groundwater WGR was contacted regarding <br /> the entries on the purge forms After evaluating the field forms, WGR concluded that instrument <br /> problems caused the anomalous temperature and electrical conductivity readings They also <br />' concluded that the individuals completing the sampling did not follow the required procedure of <br /> purging at least three casing volumes prior to sampling To correct the problem, WGR said they <br />' would provide additional training for the employees that perform the sampling To evaluate <br /> possible affects on the quality of the second quarter 2005 data caused by improper purge <br />' procedure, analytical results of the second quarter 2005 are compared to historical sampling <br /> . results in the analytical results section of this report <br /> 1 <br /> I 16000s16437 0001Archsvc%437-030 doc 2 <br />