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Mr.Harlin Knoll August 18,2000 San Joaquin County Public Health Services Project No,2007-2500-01 Environmental Health Division Page 2 southwest of the site. Stratus also supervised the installation of one air sparge well (AS- 1) in the vicinity of the active pump islands. Monitoring wells MW-9 and MW-10 were developed on May 16, 2000. Monitoring well MW-5, located in the shoulder of Lower Sacramento Road, was destroyed on May 5, 2000. The City of Lodi requested the abandonment of well MW-5 due to a proposed widening of Lower Sacramento Road. GROUNDWATER GRADIENT AND DIRECTION The second quarter 2000 groundwater monitoring event was conducted on May 17, 2000. The activities consisted of measuring groundwater levels, purging the groundwater monitoring wells, and collecting groundwater samples for chemical analysis. Groundwater levels were measured using an electronic sounding device and recorded on the field data form presented in Appendix A. Table 1 presents the historical and second quarter 2000 groundwater elevation data. Field sampling procedures are presented in Appendix B. At the time of the second quarter monitoring event, groundwater was encountered at depths ranging from 38.43 to 40.70 feet below ground surface (bgs). The measured water levels were corrected to mean sea level (MSL) and used to plot a groundwater contour map. Figure 2 presents groundwater elevations and contours for the second quarter 2000 monitoring event. All existing monitoring wells (with the exception of MW-7) and the newly installed MW-9 and MW-10 were surveyed on August 4, 2000 by Morrow Surveying, Inc. The direction of groundwater flow was calculated to be towards the south with an average gradient of 0.004 ft./ft. Groundwater flow direction and gradient are consistent with previous monitoring events. SAMPLING, ANALYSIS, AND MONITORING PROGRAM RESULTS Groundwater samples were collected from 11 monitoring wells on May 17, 2000 and forwarded to Alpha Analytical, Inc. for analysis. Samples were analyzed for total petroleum hydrocarbons as gasoline (TPHG) using United States Environmental Protection Agency (USEPA) Method 801513; benzene, toluene, ethylbenzene, and total xylenes (BTEX compounds) and for five oxygenates (MTBE, TBA, DIPE, TAME, and ETBE) using USEPA Method 8260B. Certified Analytical Reports with chain-of- custody documentation are included in Appendix C. A summary of the groundwater analytical data is presented in Table 2. Petroleum hydrocarbon products were not detected in the samples collected from MW-1, MW-6, MW-7, MW-9, and MW-10. TPHG was detected in the samples collected from MW-2 and MW-4 at concentrations of 0.067 mg/L and 0.21 mg/L, respectively. TPHG, BTEX compounds, and MTBE were detected in the samples collected from MW-3, MW-8, S-1, C\My DowmentAUSA Gasolin00651QtdyW65g200.doc STRATUS