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S E C 0 R
<br /> Conceptual Site Model
<br /> Chevron Service Station#9-6171
<br /> March 25, 2005
<br /> Page 25
<br /> and 0 51 ppm (SW1-13'), respectively The concentrations of TEL and EDB ranged from
<br /> below the method detection limits to 021 ppm (SW1-19') and 14 ppb (SW1-13'),
<br /> respectively
<br /> On December 7, 1989, two 12,000-gallon capacity fuel USTs, one 520-gallon capacity
<br /> waste oil UST, and associated product piping were installed in the southeast portion of the
<br /> property At this time, one soil sample (NSW) was collected from the new tank pit and two
<br /> soil samples (SW2 and SW3) were collected from old tank pit The concentrations of TPHg
<br /> and benzene ranged from below the method detection limits to 5 2 ppm in SW2-20119 and
<br /> 0 15 ppm in SW2-20113, respectively The concentrations of ethylbenzene and toluene
<br /> were at or below the method detection limits The concentrations of total xylenes were 0 35
<br /> ppm in SW2-20119 The concentrations of TEL ranged from below the method detection
<br /> limits to 0 18 ppm in SW2-20119 The concentrations of EDB were at or below the method
<br /> detection limits in all samples
<br /> On December 13, 1989, soil samples P1-6, 132-17, P3-5, and P4-8 were collected from the
<br /> product trenches A groundwater sample, W1, was collected from the onsite domestic well
<br /> The TPHg concentrations in soil samples ranged from below the method detection limits to
<br /> 7,200 ppm (P2-17) The BTEX concentrations in soil samples ranged from below the
<br /> method detection limits to 170 ppm (P2-17), 1,100 ppm (P2-17), 1,300 ppm (P2-17), and
<br /> 200 ppm (P2-17) respectively The TEL concentrations in soil samples ranged from below
<br /> the method detection limits to 0 89 ppm (P2-17) The ED concentrations in soil samples
<br /> ranged from below the method detection limits to 830 ppb (132-17) The TPHg
<br /> concentration in groundwater was 160 ppm The groundwater concentrations of BTEX,
<br /> TEL, EDB, and Pb were at or below the method detection limits There were unspecified
<br /> Ihydrocarbons detected in a grab sample collected from the onsite domestic well W1
<br /> In July 1990, the onsite domestic water well was destroyed In October 1990, four
<br /> groundwater monitoring wells, MW1 through MW4, were installed onsite to monitor for the
<br /> presence of petroleum hydrocarbons in groundwater Soil samples were collected from
<br /> I each boring during completion of the monitoring wells and submitted for chemical analysis
<br /> The concentrations of TPHg, TPHd, ethylbenzene, and total xylenes in the soil samples
<br /> were at or below the method detection limits The concentrations of benzene and toluene
<br /> In the soil samples ranged from below the method detection limits to 0 088 ppm (MW3-
<br /> 30 5') and 0 056 ppm (MW4-15 5'), respectively The concentrations of tetra chloroethene
<br /> (PCE), chlorobenzene (CB), 1,2-dichlorobenzene (1,2-DCB), TPHg, TPHd, and BTEX
<br /> I compounds in groundwater were at or below the method detection limits in all four
<br /> monitonng wells Groundwater sampling and analysis lasted from July 1990 to June 1998
<br /> In April 1998, the USTs, fuel dispensing facilities, two hydraulic lifts, and one sand/water
<br /> separator were removed A total of 630 yd of excavated soil was removed and properly
<br /> . disposed of Clean, imported fill material was used to backfill the excavations to original
<br /> N 1FdeslProjectslChevronlReta,R#9-61711Site conceptual modeRFINAL_CSM doc
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