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. Mr. Harlin Knoll August 19, 2002 San Joaquin County Public Health Services Project No. 2001-0103-01 Page 2 subsequently conducted a vapor extraction test on the well, in March 1994. Well MW-13 was reconstructed to a total depth of 65 feet bgs in December 1994. Vapor extraction was conducted on wells MW-13 and MW-14. Vapor extraction was initiated on well MW-14 on December 13, 1994; the date that vapor extraction was initiated on well MW-13 is not known. EMCON installed an air sparge well (AS-1) in May 1995. The date that the vapor extraction system was shut down is also not currently known. Three diesel USTs (Teichert tanks C-11 north [20,000-gallon capacity], C-11 south [20,000-gallon capacity], and C-13 [12,000-gallon capacity]), product dispensers, and product piping were removed in March 1999. Petroleum hydrocarbon impacted soil beneath the product dispensers was excavated. Stratus advanced soil boring B-17 in September 1999. Stratus abandoned monitoring wells MW-3 through MW-5 and MW-9 through MW-12 in February 2000. Stratus also oversaw the removal of a 1,000-gallon capacity waste oil tank (Teichert tank WO-4) in October 2000. Groundwater elevations in the vicinity of the site have fluctuated between approximately 106 feet bgs (1979) and 35 feet bgs (1988). All USTs have been removed from the site. Stratus submitted a Final Closure Report (July 20, 2001) and additional Data to Support Closure (December 17, 2001). San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) denied the closure request. The site was subsequently placed on a quarterly monitoring program. GROUNDWATER MONITORING On June 4, 2002, a Stratus representative measured depth to groundwater in three wells (MW-13, MW-14, and AS-1) and collected groundwater samples from the two remaining onsite groundwater monitoring wells (MW-13 and MW-14) for subjective and laboratory analyses. Floating product was not observed in any of the groundwater monitoring wells. Well MW-1 was dry. The locations of the wells are presented on Figure 1. Groundwater Elevation Second quarter 2002 groundwater levels were measured on June 4, 2002, using an electronic sounding device, and recorded on the field data sheets presented in Appendix A. Table 1 presents the second quarter 2002 groundwater elevation data. At the time of the second quarter 2002 monitoring event, groundwater was encountered in well MW-13 at a depth of 49.49 feet bgs, and in wells MW-14 and AS-1 at a depth of 49.64 feet bgs. Groundwater flow direction and gradient were not calculated, as survey • data from only two monitoring wells (MW-13 and MW-14) are available. P:ITeichertlStockton-1031Quarterly120021teichert_2Q02.doc STRATUS