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Mr Harlin Knoll . Page 2 of 3 Monitoring wells MW 1 through MW4 were purged of a minimum of five well casing volumes of water prior to sampling The physical parameters temperature, pH, and electrical conductivity were measured during the purging process Samples were collected after the physical parameters had stabilized and water levels had recovered at least 80% from pre-purged levels Purged groundwater was contained in appropriately labeled DOT- approved 55-gallon drums The drums are currently being stored onsite pending disposal Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) Samples were analyzed for the presence of TPHg and TPHd using EPA method 8015M, BTEX using EPA method 8020, and oxygenated gasoline additives, 1,2-DCA, and EDB using EPA method 8260B GROUNDWATER ANALYTICAL RESULTS No TPHg, TPHd, or BTEX were detected in any site well for the third consecutive sampling event Methyl tert butyl ether (MTBE) was the only chemical of concern detected at the site MTBE was detected in wells MW 1, MW3 and MW4 at 37 parts per billion (ppb), 400 ppb and 43 parts ppb, respectively Analytical results are summarized in Table 2 MTBE concentrations over time in site wells are illustrated on Figure 3 Attachment B contains laboratory reports and chain of custody documentation SUMMARY AND CONCLUSIONS • Groundwater levels at the site fell an average of 0 97 feet since the last round of sampling • As measured on December 13, 2001, groundwater flows northwest at a relatively flat gradient of 0 0008, which is a slight shift from the previous gradient toward the southwest • MTBE was the only analyte of concern detected at the site during this round of sampling MTBE levels increased wells MW1, MW3 and MW4, but remained below the detection limit in well MW2 Soil excavation and interim groundwater extraction measures conducted at the site appear to have successfully in removed the contaminant source Soil and groundwater analytical results suggest that no significant amounts of petroleum hydrocarbons are present in the vicinity of the former USTs However, MTBE was present at a levels exceeding the drinking water standard (13 ppb) established by the State of California in wells MW 1, MW3, and MW4 RECOMMENDATIONS . Based upon non-detect (ND) results for three consecutive rounds of sampling, analysis for TPHd, TPHg, and BTEX should be discontinued Subsequent analyses should be performed only for MTBE b=Yard/reporls/gmr/4QM200i doe