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Chemn - thevron A single soil sample was collected At 8.0 feet bgs from beneath the former waste oil UST. TPH was detected at 14.0.ppm. No detectable concentrations of PCB's or HVOC's were found at this location. In March, 1987 GTL installed three groundwater monitoring wells'(MW-1, 2, 3). Their report (Subsurface Investigation Chevron Service Station'#7780, 5!5187) describes the well installations, 'r as well as, the soil and groundwatersampling results. All soil samples were analyzed for BTEX constituents usingmodified EPA method 602. Total Hydrocarbons (TI4C) were reported- as a summation of total.BTEX and miscellaneous aromatic concentrations. The MDL was 1.0 ppm. Soil samples from MW-1 were taken:at 26.0 and -36.0'feet bgs. BTEXconstituents were-not detected in either sample.THC concentrations ranged from 8.8 to 1.2 ppm. One soil sample from 30.0-feet bgs was analyzed in MW-2. No detectable:concentrations OF-BTEX or THC were measured at this depth: The soil sample analyzed from MW-3 was taken at 34.0 feet bgs. No detectable concentrations of BTEX-or-THC were measured. Groundwater samples were collected.from MW-1,.2, and 3:on March 19, 1987. The depth to groundwater was between 39.1-.and 41.2- feet' bgs. Wafer samples were analyzed for .BTEX- constituents using.modified EPA method 602. The method detection.limit was 1.0 ppb. THC concentrations were reported>as'the summation-of total BTEX and miscellaneous aromatic concentrations. Benzene concentration measured in<MViW-1 was 272.2-ppb. THC concentration was 791.0 ppb. In MW-2 Benzene conceniration`was 835.4 ppb and THC concentration was 2399.0 ppb. The benzene concentration measured in MW-3 was 83.8 ppb. THC concentration was 327.6 ppb On June 3,1987 GTI collected soil,samples from the stockpile,of,soil onsite which was generated during the January,. 1987.tank 'removal activities. Six`samples were collected from 5.0 feet below the stockpile surface. Two composite soil samples(3:l composition) were analyzed on June 13, 1987 for BTEX constituents andTHC. The analytical methods used are not known at this time. The corresponding MDL's• were 05 ppm. No,:hydr"ocarbons"were detected above the method detection limit. The stockpiled soils-were returned to the tank pit: � In their report (R6port,Of Investigation _Chevron-Service Statio .# 9-7780 . Risk Assessment, , 1114!87), EA Engineering, Science; .and Technology, Inc. (EA):discuss all potential risks i associated with the known soil and groundwater contamination reported at the subj ect site..EA.also I _investigated five domestic water wells in-the vicinity of.the subject site for:possible hydrocarbon contamination.The, depth of completion of the five.wells ranged from 120 to 191 feet bgs. All five wells were within a quarter mile-of.the.,.subject site. Four'of the five wells were located downgradient from the subject site.Water samples were collected on'August20, 1987 and sent to a laboratory to be analyzed for THCand BTEX constituents.;The analytical.,method used was EPA method 602 using 0 a MDL of :5-ppb: The. MDL for' THC analysis was 1000.0 ppb. No hydrocarbons were detected above the MDL in all samples. On April 26, 1988 EA issued a report-(Results of-Soil and Groundwater.Investigation In The. Vicinity of Former-Chevron Service Station,#9-7780)°describing the installation of groundwater monitoring wells EA-1, 2, 3, and 4. During'Well,installation-(February,: 1988) soil samples were collected and analyzed for TPHGas and BTEX constituents using modified.EPA methods 8015-and 8020. The MDL's used were 5.0 ppm for the 8015 method and 0.2 ppm'for the 8020 method. Soil samples selected for.analysis were those from depths at which hydrocarbon vapors were detected �w,.Y aua