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Mr.Harlin Knoll December 8,2000 San Joaquin County Public Health Services Project No.2007-0065-01 Environmental Health Division Page 2 Pinnacle prepared and submitted a RAP in January 1999. The RAP recommended the construction, installation and operation of a soil vapor extraction and air sparge system to mitigate the petroleum hydrocarbon impact to soil and groundwater. 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 SUES in July and August 2000. A system startup and source test were 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 third quarter 2000 groundwater monitoring event was conducted on September 22, 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 third quarter 2000 groundwater elevation data. Field sampling procedures are presented in Appendix B. At the time of the third quarter monitoring event, groundwater was encountered at depths ranging from 39.80 to 42.67 feet below ground surface (bgs). 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 third quarter 2000 monitoring event. C Troject FileslUSA Gasohne10651Qtr1y13Q00.doc ' 5r, ACAM5