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NEW %.I
<br /> ARG4DIS GERAGHTY&MILLER
<br /> adjacent to the waste oil tank. Maximum concentrations of petroleum hydrocarbons
<br /> were detected in samples taken from approximately 20 feet below ground surface.
<br /> The two samples with the highest detections, samples KB3 and K135, had TPHg
<br /> concentrations of 239.0 and 370.0 mg/Kg, respectively. Sample K133 indicated
<br /> concentrations of BTEX compounds at 11.2, 18.0, 18.2, and 41.9, respectively.
<br /> Sample KB5 indicated concentrations of BTEX compounds at 6.58, 38.6, 40.1, and
<br /> 53.15, respectively.
<br /> During tank removal between March and April, 1988, a significant amount
<br /> of soil was excavated from the site. Soils within the tank excavation were removed
<br /> to a depth of 30 feet. The results, reported by Applied Geosystems (Report
<br /> Subsurface Investigation, No. 38012-5, Applied Geosystems, December 12, 1990),
<br /> indicated that total petroleum hydrocarbons calculated as gasoline (TPH-g) in soil
<br /> samples taken from the excavation, with one exception, ranged from less than 2 to
<br /> 38 mg/Kg and concentrations of benzene(B) ranged from nondetect to 1.72 mg/Kg..
<br /> One soil sample taken from the west end of tank T-1 at 16 feet below ground surface
<br /> (bgs) indicated a TPHg concentration of 582 mg/Kg and benzene (B), toluene (T),
<br /> ethylbenzene, and total xylenes (X) concentrations of 0.60, 6.50, 10.40, and 39.10
<br /> mg/Kg, respectively. A soil sample taken from beneath the product line were found
<br /> to have a TPHg concentration of 6 mg/Kg. No benzene was detected in the product
<br /> line sample. After additional excavation was conducted, a soil sample taken from 26
<br /> feet bgs indicated a TPHg concentration of 13 mg/Kg and BTEX concentrations of
<br /> 0.29, 1.07, nondetect, and 1.32 mg/Kg, respectively. No hydrocarbons were
<br /> detected beneath the waste oil tank.
<br /> Between June 1988 and February 1992, Applied Geosystems (AGS) and
<br /> RESNA Industries installed I1 soil borings (B-1 through B-11). Seven of the
<br /> borings were completed as monitoring wells (MW-1 through MW-7) and three were
<br /> completed as soil vapor extraction (SVE) wells (VW-1 through VW-3). Monitoring
<br /> Wells MW-1, MW-2, MW-3, and MW-6 are located on site and Wells MW-4,
<br /> MW-5, and MW-7 are located northeast (downgradient) of the site. The SVE wells
<br /> are located in the vicinity of the former product islands.
<br /> A SVE test was performed in March 1992 by RESNA (Vapor Extraction
<br /> Test Results, letter report, RESNA, January, 4, 1993). RESNA reported that the
<br /> results of this test show that, with a wellhead flow rate of 43 cubic feet per minute
<br /> (cfm), an estimated radius of influence of approximately 25 feet could be achieved
<br /> for one vapor extraction well.
<br /> In July 1994, Pacific Environmental Group, Inc. (PEG) installed two off-site
<br /> monitoring wells (MW-8 and MW-9); (Groundwater Monitoring Well Installation,
<br /> letter report, Pacific Environmental Group, October 4, 1994). Sample results from
<br /> these monitoring wells indicated that the lateral extent of dissolved hydrocarbons in
<br /> Our ref.: Page:
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