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• Quik Stop Market No 121 CCI Project No 12118-2 Page 3 Groundwater Sampling On April 18, 2001, CCI sampled all nine wells for the quarterly sample round Before groundwater sampling, CCI measured the depth to groundwater using an electronic sounding tape and field-checked the wells for the presence of free-floating product by collecting a sample in a clear acrylic bailer Free-floating product was not observed Each well was purged of stagnant water prior to the collection of a sample Normal field measurements, including pH, conductivity, and water temperature, were periodically recorded during the purging process A sample was collected when these parameters stabilized to within 10% of each other At least three well casing volumes of groundwater were purged from each well before sampling Samples were (a) collected with a clean disposable bailer, (b) transferred to appropriate laboratory-supplied bottles, ( c) labeled, (d) logged on a chain-of-custody form, and (e) placed in a chilled ice chest for transportation to a state-certified laboratory Monitoring well purge data is summarized in data Table 1 Laboratory Analysis The groundwater samples were submitted to North State Environmental (North State), a state- certified laboratory located in South San Francisco, California, for chemical analysis The laboratory employed methods approved by the California Regional Water Quality Control Board (CRWQCB) and the EPA The groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) and benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary butyl ether (MTBE), using EPA Test Method 8015 and 8020 MTBE concentrations were confirmed using EPA Test Method 8260 Summary of Laboratory Results The seven groundwater monitoring wells (screened from approximately 9 to 24 feet) were sampled and found to be impacted with petroleum hydrocarbons and MTBE Monitoring well MW-1, located on the northwest side of the site (Figure 2), near the intersection of Union Road and West Louise Avenue, was reported to contain TPHg at a concentration of 170 micrograms per liter(ug/1), benzene at 2 ug/l and MTBE at 13,000 ug/l Monitoring well MW-2, also located on the north side of the site, was reported to have 81 ug/l TPHg, benzene at 2 ug/l and MTBE at 29 ug/l Monitoring well MW-3, located on the southeast side of the property, was reported to contain 460 ug/l TPHg and benzene at I 1 ug/l This well was reported to have MTBE at a concentration of 98,000 ug/l Recovery well RW-1, located near the east side of the fuel tanks, was also reported to contain 560 ug/l TPHg, 6 ug/l benzene and 180,000 ug/l MTBE Monitoring well MW-4, screened from 33 to 43 feet, was reported to contain 86 ug/l TPHg and • 1,200 ug/l MTBE Monitoring wells MW-5, located on the southwest side of the site, and MW-