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After the on-site gasoline and used oil USTs were removed from the site by Blaine in February <br /> 1988, EA installed morutoring wells on site Six, 4-inch diameter, monitoring wells were <br /> installed in November 1988, designated Wells MW-1 through MW-6 Soil samples collected <br /> from the soil borings were found to contain concentrations of total purgeable petroleum <br /> hydrocarbons calculated as gasoline (TPPH-g) up to 3,300 ppm Groundwater samples were <br /> collected and analyzed by EPA Method 8015 for TPPH-g and BTEX compounds Petroleum <br /> hydrocarbons were not detected in Well MW-1, the apparent upgradient well The highest <br /> concentrations were measured in the two wells closest to the backfilled UST pit, Wells MW-3 <br /> and MW-4 Well MW-3 contained 9,300 parts per billion (ppb) TPPH-g, with 2,700 ppb <br /> benzene, 360 ppb toluene, 2,800 ppb ethylbenzene, and 2,000 ppb xylenes The hydrocarbon <br /> concentrations appeared to decline with distance from the backfilled fuel pit as seen in <br /> Wells MW-2, MW-5, and MW-6 Depth to groundwater was found to be 35 to 37 feet bgs <br /> In November 1988, while installing Well MW-5, an unknown, 550-gallon UST was found and <br /> accidentally punctured After analyzing a sample from the tank, it was found to contain "old <br /> product," probably gasoline The hole in the tank was covered during its removal During <br /> this tank's excavation, product piping was uncovered leading to two additional unknown <br /> tanks These tanks were 4,000 and 3,000 gallons in capacity and had been abandoned by <br /> tearing holes in their tops and filling them with sand All three of the tanks were constructed <br /> of steel No hydrocarbons were detected in the air above or within these tanks by the organic <br /> vapor monitor The three tanks were removed in December 1988 by Blaine They performed <br /> UST removal and soil sampling associated with the removal of the three additional USTs from <br /> beneath the site One soil sample was taken from the 550-gallon UST pit The soil sample <br /> taken from the pit was analyzed for the presence of high boiling point hydrocarbons, BTEX <br /> compounds, organic lead, and ethylene dibromide Laboratory analysis of the soil sample <br /> taken from the pit revealed non-detectable amounts of all constituents analyzed One soil <br /> sample was taken from the bottom of the 3,000- and 4,000-gallon UST excavation The <br /> sample was analyzed for the presence of high boiling point hydrocarbons, BTEX compounds, <br /> organic lead, and ethylene dibromide Laboratory analysis of the soil sample taken from the <br /> 3,000- and 4,000-gallon UST pit revealed non-detectable amounts of all constituents <br /> analyzed <br /> Groundwater monitoring indicated the groundwater flow to be to the northeast at an <br /> approximate gradient of 0 002 foot per foot <br /> EA drilled seven soil borings in January 1989 Due to the high TPH contamination in the soils <br /> at depths of 31 feet bgs, m-situ remediation was selected Five of the soil borings were <br /> completed as soil vapor extraction (SVE) wells (V-1 through V-5), while the remaining two <br /> borings were developed into groundwater monitoring wells (MW-7 and MW-8) The site was <br /> found to be well suited for vapor extraction as a remediation treatment, and an SVE system <br /> 3201337B/CAP AMD DOC A- 2 November 30, 1995 <br />