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25 January 2001 <br /> AGE-NC Project No 99-0559 <br /> Page 2 of 14 <br /> 23 UNDERGROUND STORAGE TANK REMOVAL <br /> AGE has been informed that on 06 January 1999, Oil Equipment Service (OES) of San Andreas, <br /> California, removed four UST's identified as T-1 (5,000-gallon gasoline UST), T-2 (10,000-gallon <br /> gasoline UST), T-3 (10,000-gallon gasoline UST), T-4 (500-gallon waste oil UST), fuel dispensers <br /> and associated product piping from the northeast portion of the site During excavation, two <br /> previously unknown USTs, identified as USTs #5 and #6, were discovered On 16 February 1999 <br /> USTs No 5 and No 6 were removed and soil samples were collected beneath each former US i <br /> position <br /> On 22 February 1999, approximately 100 cubic yards of hydrocarbon-impacted soil was excavated <br /> and approximately 125 cubic yards of hydrocarbon-impacted stockpiled soil were hauled from the <br /> site A total of 13 loads of soil were hauled to BFI Vasco Road Landfill (BFI) in Livermore for <br /> disposal <br /> Following soil excavation and removal, additional soil was excavated for the new UST installation <br /> Soil samples were collected from the enlarged excavation by AGE and four soil samples from the <br /> • new stockpile for the purpose of characterization for disposal <br /> 24 SITE ASSESSMENT AND MONITORING WELL INSTALLATION <br /> On 14 to 17 December 1999, AGE advanced four soil probe borings at the site Probe borings were <br /> advanced in the area surrounding the current UST locations to maximum depths of 62 feet below <br /> surface grade(bsg) On 25 and 26 January 2000, four ground water monitoring wells (MW-1 through <br /> MW-4) were installed at the site <br /> The most intensely fuel connponent-impacted (methyl-tertiary butyl ether MTBE) soil was in the <br /> area of borings B2, MW-2, and MW-3 at depths as great as 65 feet A significant mass of <br /> hydrocarbons was present in the vicinity of well MW-2 from 15 feet to 65 feet bsg and to a lesser <br /> degree south of the former USTs, in the area of well MW-3, from 45 feet bsg to 65 feet bsg <br /> Two ground water monitoring events have been conducted at the site, along with several single-well <br /> sampling events, and continuous ground water level monitoring events The events included <br /> measurement of free product thickness in well MW-2 During the past two quarters, removal of free <br /> product has been conducted Approximately sax inches of free-product has been regularly observed <br /> to well MW-2 <br /> The highest concentrations of dissolved total petroleum hydrocarbons quantified as gasoline (TPH-g) <br /> . and MTBE have been documented in the area of the former UST and approximately 75 feet <br /> Advanced CeoLivironmental,lnc <br />