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27 October 2003 <br /> AGE-NC Protect No 98-0450 <br />' Page 2 of 17 <br /> groundwater monitoring event,TPH-g was detected at 12,000 micrograms per liter(p g/1)and BTEX <br /> compounds were detected at concentrations up to 1,900 µg/1 (xylene) <br />' 2 2 UST REMOVAL <br /> In February 1998,three USTs and the associated product distribution system were removed from the <br /> site, and soil samples were collected for analysis, details of the UST removals and soil sampling <br /> were presented in reports by Thorpe Oil Company to the San Joaquin County Environmental Health <br /> ' Department (EHD) The soil samples were analyzed for TPH-g, BTEX compounds and the <br /> oxygenated fuel additives methyl tertiary butyl ether (MTBE), tertiary butyl alcohol (TBA), di- <br /> isopropyl. ether (DIPE), ethyl tertiary butyl ether (ETBE) and tertiary amyl methyl ether(TAME), <br /> ethanol in accordance withEPAmethods 8015 Modified,8020 and 8260 Modified,respectively The <br /> soil samples were also tested for total lead <br /> ' Petroleum hydrocarbon-impacted soil was detected in the northern portion of the UST area at a depth <br /> of 15 feet below surface grade (bsg), and at the western edge of the dispenser islands at a depth of <br /> ' . 5 feet bsg The analytical results of UST soil samples are summarized in Tables 1 and 2 <br /> ' 23 ADDITIONAL SITE ASSESSMENT <br /> Between 28 and 30 October 1998,three ground water monitoring wells,two soil gas/vapor wells and <br /> ' four soil bonngs were installed on-site Quarterly ground water monitoring continued until <br /> 11 December 2002 <br /> ' 2 3 1 Soil Boring and Monitoring Well Installation Procedures <br /> ' The following is a summary of assessment and well construction procedures <br /> • Soil boring BMW3 was completed as groundwater monitoring well BMW3 at the northwest <br /> ' edge of the site, and soil boring BMW5 was completed as ground water monitoring well <br /> BMW5 at the eastern edge of the site The well borings were advanced to a total depth of <br /> 60 feet bsg and completed with 0 02-inch slotted screen from depths of 40 to 60 feet bsg A <br /> ' filter pack was installed from 38 to 60 feet bsg in both wells using #3 Lonestar sand <br /> Bentonite chips were used to make a 2-foot plug above the sand filter packs The remairung <br /> annular spaces in the monitoring well borings were backfilled to within one foot the surface <br /> ' with portland cement A traffic-rated well box(8-inch diameter)was installed over each well, <br /> in accordance with County regulations <br /> Advanced GeoEnvironmentai,Inc <br />