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1 2 2 Prelimina Invests anon and Evaluation � <br /> On January 5 and 6, 1999, Ramage Environmental conducted a preliminary investigation <br /> and evaluation, which included the drilling of five on-site soil borings for soil sampling <br /> and analysis Three of the soil borings were converted to groundwater monitoring wells <br /> The newly installed wells were developed, surveyed, monitored and sampled on January <br /> 11, 1999 Soils encountered beneath the site consisted of a fining-upward sequence of <br />' fine-grained siliciclastic sediments The depth to static groundwater beneath the site <br /> ranged from 39 31 to 40 34 feet bgs Groundwater flow was to the south-southeast at a <br /> gradient of 0 05 foot/foot <br /> A metal detection survey conducted at the site, on January 13, 1999, discovered strong <br /> metallic signals in the vicinity of the former UST excavation The metal may be drums of <br /> waste not accounted for from earlier site investigation activities and other material used <br /> to backfill the former UST excavation <br /> In soil, the highest concentrations of gasoline hydrocarbons were detected in the sample <br /> collected at 30 feet below ground surface (bgs) from the soil boring for MW-2 This <br /> sample, collected directly beneath the former UST excavation, contained 2,400 mg/kg of <br /> TPH-as-gasoline and detectable concentrations of toluene, ethylbenzene and xylenes <br /> Laterally, the extent of impacted soil appears to be limited to the footprint of the former <br /> UST excavation <br /> Between January 1999 and January 2000, groundwater in the three monitoring wells was <br /> sampled on a quarterly basis The highest concentrations of gasoline hydrocarbons <br /> were detected in MW-2, installed through the former UST excavation During this time <br /> period, the highest concentrations detected in groundwater included 160,000 µg/I of <br /> TPH-as-gasoline, 7,800 µg/I of benzene, 64,000 µg11 of toluene, 6,100 µg/I of <br /> ethylbenzene, 35,000 gg/I of xylenes, 2 6 gg/I of methyl tertiary butyl ether (MTBE), and <br /> 100 µg/l of tertiary butanol (TBA) The lateral extent of impacted groundwater is <br /> undefined to the north (upgradient), west and south (downgradient) of the former UST <br /> excavation However, the lateral extent is defined to the northeast of the former USTs by <br /> MW-1 <br /> i <br /> 4 <br />