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Cieologird(Technics inc. Page 5 Additional Site Characterization And 1"Quarter 2004 Groundwater Monitoring Project No.425.2 March 22, 2004 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 the movement of and ensure the integrity of the samples. As required under AB2886, the depth to groundwater data was submitted electronically to �. GeoTracker on February 9, 2004, and the confirmation number is 5229664444. 2.2.2 Groundwater Laboratory Analyses Groundwater samples collected on January 3, 2004, were delivered to Sherwood Labs of Hilmar, California (certification#1400) for analyses of. • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX) by EPA method 8020 �. • Gasoline Range Organics (TPH-G)by EPA method 8020/8015(M) • MTBE by EPA method 8020 ❑ Positive results were confirmed by EPA method 8260 The results of the laboratory analyses are listed in Table 3 of Appendix A. Detection limits and analytical results are presented in Appendix B. As required under AB2886, the depth to groundwater data was submitted electronically to GeoTracker on January 23, 2004, and the confirmation number is 6278842151. +.. 2.2.3 Groundwater Parameters Dissolved oxygen measurements at the site were generally between 1.0 and 2.0 ppm during ..,� the January 3, 2004, groundwater-monitoring event. The two exceptions to this were MW-2 with 0.02 ppm and MW-5 with 0.89 ppm. These two wells are impacted with the highest TPH-G concentrations at the site; 29,100 p.g/L and 2,040 µg/L, respectively. The dissolved oxygen conditions are in a range that is conducive to natural biodegradation. +� Oxidation-reduction potential measured at the site is both negative and positive. In general, the water table wells tend to be negative while the intermediate and deep wells tend to be positive. This may indicate the contamination does not have a downward component to ,.., migration. It may also indicate aquifer characteristics unique to depth or confining units. The groundwater temperature at the site ranges between 69° and 76°F. The temperature is slightly elevated in the most highly impacted areas, suggesting some biodegradation activity may be present. The measured pH in the water table wells range between 7.04 and 8.11. This pH range may be conducive to maintaining aerobic biodegradation activity. Groundwater parameters measured during the January 3, 2004, groundwater-monitoring �- event are summarized in Table 4 included in Appendix A. 2.3 Additional Site Work Well Development On October 6, 2003, Del-Tech personnel arrived on site and developed two newly installed groundwater-monitoring wells (MW-101 and MW-201). Development included surging the