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Geo(oguafTechntcs Inc Page 3 - Groundwater Monitoring Report Project No 724 2 • dune 4, 1999 Extreme care was exercised while collecting samples to prevent agitation of the water contained in the bailer Water samples were transferred from the bailer into 40-m1 VOA vials preserved with hydrochloric acid using a bottom-emptying device that minimizes sample aeration during transfer of the sample All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory The sampling technician while collecting all samples wore disposable gloves A chain of custody document, listing all samples collected and their intended analyses, accompanied the samples from field to the laboratory, thereby providing a means to track ' their movement and insure their integrity ' 1.3 Laboratory Analyses The groundwater samples collected on January 25, 1999 were delivered to BSK Labs of ' Fresno, California Due to a heavy workload, the samples were sub-contracted out to Castle Analytical Laboratory of Atwater, California (certification 42079) for analysis of • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX)by method EPA method 602 ' • Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 5030/8015(M) o Methyl Tertiary Butyl Ether(MTBE) by EPA method 602 The detection limits for the above analyses are listed in Table 2 of Appendix A whole the lab analytical results are presented in Appendix B ' 2 0 FINDINGS AND DISCUSSION The results of the groundwater sample analysis show the following • Low levels of TPH-G were detected in MW-1 • Moderate to high levels of Benzene and Ethyl Benzene and TPH-G compounds are present to MW-2 • Low levels of Benzene and TPH-G were detected in MW-3 • BTEX and TPH-G concentrations increased significantly in MW-2 but remained relatively consistent with past events in the other five wells • MTBE was detected in the water samples from MW-2 During field monitoring/well purging work, water quality parameters were measured, including Oxidation-Reduction Potential (ORP) The ORP results show a direct correlation Iof negative values for wells in the contaminated zone Thus suggesting that natural biodegradation of these chemicals is not a significant attenuation process To date, no wells are located outside the contaminated zone I I