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• Mr. Harlin Knoll July 31,2002 San Joaquin County Public Health Services Project No. 2007-0065-01 Page 3 SAMPLING, ANALYSIS, AND MONITORING PROGRAM RESULTS Groundwater samples were collected from 11 monitoring wells on May 2, 2002, and forwarded to Alpha Analytical, Inc. for chemical analysis. Groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHG) using United States Environmental Protection Agency (USEPA) Method SW8015B/DHS LUFT Manual, and for benzene, toluene, ethylbenzene, and total xylenes (BTEX compounds), methyl tertiary butyl ether (MTBE), tertiary butyl alcohol (TBA), disopropyl ether (DIPE), tertiary amyl methyl ether (TAME), and ethyl tertiary butyl ether (ETBE) using USEPA Method SW8260B. Certified Analytical Reports with chain-of-custody documentation are included in Appendix C. Groundwater analytical data are included in Table 2, and TPHG, benzene, and MTBE data are summarized on Figure 3. The highest concentration of TPHG (0.76 milligrams per liter [mg/L]) was detected in the sample collected from well MW-4, and the highest concentration of MTBE (91 micrograms per liter [pg/L]) was detected in the sample collected from well MW-3. TPHG and TBA were also detected in the sample collected from monitoring well MW-3. Benzene and xylenes were only detected in the sample collected from monitoring well S-1 (2.1 µg/L and 0.63 µg/L, respectively). MTBE was also detected in samples collected from monitoring wells MW-4, MW-8, S-1, and S-2. Petroleum hydrocarbons and fuel oxygenates were reported below laboratory detection limits in the samples collected from monitoring wells MW-1, MW-2, MW-6, MW-7, MW-9, and MW-10. SOIL VAPOR EXTRACTION SYSTEM Stratus operated and maintained the SVES during second quarter 2002, under an authority to construct (ATC) permit issued by the SJVUAPCD. The system startup was conducted on August 15, 2000. The SVES consists of a 150 cubic feet per minute catalytic oxidizer with a 5 horsepower blower. Soil vapors are extracted from the subsurface using a blower, and abated in a catalytic oxidizer before discharge to the atmosphere. Operating time, flow rates and analytical results of air samples, and the mass extraction and emission rates of the SVES are shown on tables 3, 4, and 5, respectively. Field data sheets are presented in Appendix A. Figure 4 presents changes in influent TPHG concentrations and cumulative mass removed since startup._ Seven site visits were conducted during the second quarter 2002 to monitor, optimize system performance, and conduct maintenance. Influent and effluent air samples were collected on April 1, 2002, May 7, 2002, and June 4, 2002, and forwarded to Alpha PAUSA Gasolinel00651Qtrly120021USA_65_2Q02.doe 5TRATU5