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S E C O R
<br /> Conceptual Site Model
<br /> . Chevron Service Station#9-6171
<br /> March 25, 2005
<br /> Page 24
<br /> yd of impacted soil was removed from the property and properly disposed of In 1997, the
<br /> service station was decommissioned In August 1998, four groundwater monitoring wells
<br /> were destroyed and the site was granted closure by the SJCDEH Closure was granted
<br /> based on the following criteria 1) primary and secondary sources were removed, 2) land
<br /> use of the site no longer dispensed fuels, 3) the closest well to the property is
<br /> approximately 1,350 feet to the east, 4) petroleum hydrocarbon concentrations in
<br /> groundwater were reported as below the method detection limits for a minimum of 24
<br /> months, and 5) any residual contaminants are contained in shallow soil where natural
<br /> attenuation Is expected to continue and degrade the hydrocarbons in a reasonable amount
<br /> of time The site currently consists of several different retail stores
<br /> 66.1 Sampling and Analyses
<br /> On November 17, 1989, Kaprealian Engineering, Inc (KEI) removed two 10,000-gallon
<br /> capacity USTs, one 280-gallon capacity waste oil tank, and associated product piping from
<br /> the northwest portion of the property At this time, five soil samples were collected four
<br /> from beneath the fuel tanks (Al, A2, 131, and 132) and one from beneath the oil tank (W01)
<br /> Analyses of the soil samples indicated TPHg concentrations from below the method
<br /> detection limits to 6,500 ppm (132) The maximum concentrations of BTEX reported were
<br /> I . 70 ppm (132), 770 ppm (132), 1,400 ppm (B2), and 230 ppm (132) respectively Tetraethyl
<br /> lead (TEL) concentrations were reported from below the method detection limits to 1 4 ppm
<br /> (132) Ethylene Dibromide (EDB) concentrations were reported from below the method
<br /> detection limits to 1,000 ppb (132) The concentrations of TPHg, BTEX, TEL, and EDB in
<br /> the soil sample W01 were below the method detection limits However, the concentrations
<br /> of chromium (Cr), lead (Pb), and zinc (Zn) were 16 ppm, 1 1 ppm, and 25 ppm,
<br /> respectively
<br /> On November 20, 1989, KEI collected seven samples from the product piping trenches
<br /> four from the fuel piping (P1-P4), two from the vapor piping (V1 & V2), and one from the
<br /> waste oil remote fill piping (WP1) The concentrations of TPHg ranged from below the
<br /> method detection limits to 43 ppm (P1) The concentrations of BTEX ranged from below
<br /> the method detection limits to 1 9 ppm (P2), 4 8 ppm (P2), 3 9 ppm (P2), and 0 84 ppm
<br /> (P4), respectively The concentrations of TEL and EDB were at or below method detection
<br /> limits The concentrations of TPHg, BTEX, TEL, and EDB were below the method
<br /> detection limits for soil sample WP1 However, the concentrations of Cd, Cr, Pb, and Zn
<br /> were 2 0 ppm, 26 ppm, 2 0 ppm, and 40 ppm, respectively
<br /> IOn December 5, 1989, the contaminated soil from the fuel tank pit was removed At this
<br /> time, soil samples SW1 through SW6 were collected from various depths along the
<br /> sidewalls and bottom of the pit The concentrations of TPHg ranged from below the method
<br /> detection limits to 16 ppm (SW1-13') The concentrations of BTEX ranged from below the
<br /> method detection limits to 058 ppm (SW1-13'), 1 2 ppm (SW1-13'), 30 ppm (SW1-13'),
<br /> N 1Fiies\Projects\Chevron\Retadl#9-61711Site Conceptual ModeRFINAl._CSM doc
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