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Mr. Harlin Knoll May 16, 2001 Page 2 Project No. 2007-0065-01 On May 4 and 5, 2000, Stratus supervised the installation of two groundwater monitoring wells (MW-9 and MW-10) to assess the lateral extent of petroleum hydrocarbon impact southwest of the site. These monitoring wells were developed on May 16, 2000. Stratus also supervised the installation of one air sparge well (AS-1) in the vicinity of the active pump islands. 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. 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 location of the wells is shown on Figure 2. During the resurvey MW-7 was not located. Stratus oversaw the construction and installation of a SVES in July and August 2000. A system startup and source test was conducted on August 15, 2000. The results of the startup and source test were reported to San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD) on October 19, 2000. GROUNDWATER GRADIENT AND DIRECTION The first quarter 2001 groundwater monitoring event was conducted on February 23, 2001. 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 first quarter 2001 groundwater elevation data. Field sampling procedures are presented in Appendix B. At the time of the first quarter monitoring event, groundwater was encountered at depths ranging from 37.00 to 40.59 feet below ground surface (bgs). Groundwater elevations increased approximately 0.5 feet since the last sampling event (November 2000). The measured water levels were corrected to mean sea level (MSL) and used to plot a groundwater elevation contour map. Figure 2 presents groundwater elevations and contours for the first quarter 2001 monitoring event. Groundwater elevations onsite appear to be affected by soil vapor extraction. South of the site, the direction of groundwater flow was calculated to be towards the south- southeast with an average gradient of 0.003 ft./ft. Groundwater flow direction and gradient outside of the radius of influence of the SVES are consistent with previous monitoring events. • CAProject FileslUSA Gaso1ine100651Qtr1y\USA 0065 1Q01-doc $rRAW5