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4 <br /> groundwater During the installation of the boring, the water within the outer casing was <br /> removed following the completion of the boring to 34 feet and 40 feet to reduce the possnbihty <br /> of cross contamination between hthologic layers Dewatering of the well was not successful at <br /> the shallow depth but was successful at 40 feet bgs <br /> Soil samples collected using the EnviroCoreTM stainless steel sleeves were sealed, <br /> placed on ice, and transported to Sequoia Analytical, Inc (Sequoia), along i appropriate <br /> chain-of-custody documentation All of the soil samples were analyzed f T as gasoline <br /> and BTEX with MTBE A summary of analytical results for the vertic eh eation oil boring <br /> (NDSB) is included in Table 1 A copy of the analytical report is includ in chrn t 4 <br /> Results from this investigation demonstrated thtfibgs <br /> ns present in the shallow <br /> subsurface near the area of the former tank pit are not miward No hydrocarbons <br /> were detected in the shallow subsurface (5 5 feet bgs), 510 mg/kg of TPH as <br /> gasoline at 18 feet bgs Samples collected from 21 and ntained TPH as gasoline <br /> at concentrations of 2 6 mg/kg and 3 2 mg/kg, respectirocarbons were detected <br /> in soil samples collected from 31.5, 35, 4 45 feet bgs <br /> . FEASIB I� SIS <br /> Geraghty & Miller has reviewed th fe bility and cost-effectiveness of remediation <br /> methods that reduce c centr ons of pe leum hydrocarbons in the subsurface An <br /> acceptable solution st es a impacts of petroleum hydrocarbons in the vadose zone, <br /> capillary fringe, an satura one <br /> VADOSE ZONE/CA LL Y FRINGE <br /> Soil vap extraction (SNE) and excavation were options considered for source removal <br /> in a dos zon The reduction of the vadose-zone source will improve the quality of the <br /> g undw r re ucing the dissolution of petroleum hydrocarbons to groundwater SVE has <br /> the a vantage of enhancing bioactivity, minimizing the impact to station operation and <br /> renovate d lower cost, which together led to the selection of SVE as an interim remedial <br /> measure instead of the excavation and disposal of all impacted soil The SVE system installa- <br /> tion was completed in February 1997 and is documented in the CAP dated May 29, 1997. <br /> Project No RC0309 010 <br /> GERAGHTY&MILLER, INC <br />