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lw ec0100 and en.mInIent,inc. 2. Site Background removed soil and one 2 feet below the removed UST at a depth of approximately 7 feet bgs. A slight odor was noted by the SJCEHD inspector in stockpiled material; however, no odor or discoloration was noted in the tank pit. Both soil samples were analyzed for volatile organic compounds (VOCs); total petroleum hydrocarbons (TPH) as gasoline (TPH-g), diesel (TPH-d), and motor oil (TPH-mo); benzene, toluene, ethylbenzene, and xylenes (BTEX); and total lead. The analytical results of the tank pit soil sample indicated only a concentration of total lead(17 milligrams per kilogram [mg/kg]) above the laboratory reporting limit. The analytical results of the stockpile soil sample indicated concentrations of TPH-d(190 mg/kg), TPH-mo (11 mg/kg), TPH-g(1.1 mg/kg), and total lead(15 mg/kg) above the laboratory reporting limit. Based upon the low concentration of contaminants in the tank pit sample and the removal of the stockpile material from the site, the SJCEHD issued a case closure letter for this diesel UST, dated June 10, 1994. 550 gallon gasoline UST: A 550-gallon gasoline UST, which was located approximately 10 feet southeast of the southwest corner of the fire station, was removed on June 28, 1989, under permit and inspection by the SJCEHD. One soil sample was collected for analysis at the fill end of the UST in the tank pit, approximately 8 feet bgs. A slight odor was noted by the SJCEHD inspector of the soil in the tank pit. The soil sample was analyzed for VOCs, TPH-g, BTEX, and total lead. The analytical results of the tank pit soil sample indicated concentrations of TPH-g (190 mg/kg), toluene (3.7 mg/kg), xylenes (I 10 mg/kg), ethylbenzene (4.1 mg/kg), and total lead(15 mg/kg) above the laboratory reporting limit. At the request of the SJCEHD, four direct push borings were advanced on site by Twinning Labs in the vicinity of the removed gasoline UST on December 20, 1996. Soil samples and one groundwater sample were collected for analysis. Soil and groundwater samples at one of the boring locations contained detectable concentrations of petroleum hydrocarbons. Further investigation was conducted on site at the request of the SJCEHD on July 20, 1998, when one monitoring well (MW-1)was installed by Advanced GeoAnalytical at the location of the former gasoline UST. Soil samples were collected from the monitoring well boring at intervals between 20 and 50 feet bgs. The analytical results indicated concentrations of TPH-g(800 mg/kg), toluene (37 mg/kg), xylenes (87 mg/kg), ethylbenzene (17 mg/kg), and methyl tert butyl ether(MTBE) (0.055 mg/kg). Soil samples were not collected from the ground surface to 20 feet bgs. Monitoring well MW-1 was sampled quarterly for one year in 1999. Review of results from the fourth quarter monitoring event indicate the presence of MTBE only at a concentration of 0.04 parts per million. On March 16, 1999, two additional monitoring wells were installed by ATC Associates on site; one located approximately 8 feet northwest of the northwest corner of the fire station and one approximately 8 feet east of and roughly centered on the fire station building. No soil samples were collected from these borings during installation of the monitoring wells. These two monitoring wells were sampled quarterly for one year in 1999 and no chemicals were detected above the laboratory reporting limits during the four quarters of monitoring. The groundwater monitoring reports of the three on site monitoring wells indicate groundwater flow to the east- southeast and southeast. Following one year of quarterly groundwater monitoring, the site was granted case closure by the SJCEHD in a letter dated April 17, 2000. 2-3