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SECOR
<br /> Conceptual Site Model
<br /> Chevron Service Station#9-6171
<br /> March 25,2005
<br /> Page 20
<br /> pg/L Concentrations of BTEX ranged from below the method detection limits to 21,000
<br /> µg/L, 15,000 µg/I-, 454 µg/L, and 6,950 µg/L, respectively
<br /> In March of 1994, a SVE system was Installed and put Into operation to remove elevated
<br /> concentrations of TPHg, BTEX, and MtBE from the groundwater In the fall of 1996,
<br /> Condor Earth Technologies, Inc , (CET) took over the site and determined that the SVE
<br /> system was Inadequate because It did not appear to meet the air pollution control discharge
<br /> permit condition of 95% destruction efficiency Pending groundwater sample analyses, the
<br /> SVE operation was to be suspended and the CET recommended that a CatOx unit be
<br /> Installed to replace the SVE system No additional wells would need to be drilled because
<br /> the CatOx system would operate using the existing SVE wells
<br /> In May 1998, two sod borings (SB-1 and SB-2) were advanced on either side of the pump
<br /> Island canopy The concentration of TPHg In soil samples collected from SB-1 ranged from
<br /> below the method detection limits to 6,000 mg/kg MtBE concentrations ranged from below
<br /> the method detection limits to 37,000 µg/kg Concentrations of BTEX ranged from below
<br /> the method detection limits to 62,000 µg/kg, 300,000 µg/kg, 86,000 µg/kg, and 440,000
<br /> pg/kg, respectively The concentration of TPHg In soil samples from SB-2 ranged from
<br /> I below the method detection limits to 580 mg/kg MtBE concentrations ranged from below
<br /> the method detection limits to 91 µg/kg Concentrations of BTEX ranged from below the
<br /> method detection limits to 2,400 µg/kg, 16,000 µg/kg, 8,200 deg/kg, and 50,000 µg/kg,
<br /> I respectively Six groundwater grab samples were collected during the drilling of SB-1 and
<br /> SB-2 The concentrations of TPHg In the groundwater samples ranged from below the
<br /> method detection limits to 430 mg/L The concentrations of MtBE In groundwater samples
<br /> ranged from 190 µgll- to 77,000 ltg/L The concentrations of BTEX In groundwater were
<br /> reported as follows benzene ranged from 22,000 µg/L to 48,000 µg/L, toluene ranged from
<br /> 24,000 µg/L to 47,000 µg/L, ethylbenzene ranged from 1,820 µg/L to 3,400 p.g/L, and total
<br /> xylenes ranged from 12,000 µg/L to 17,000 µg/L Based on these findings, the CatOx SVE
<br /> system was Installed in March of 1999 The system operated through February 2001, at
<br /> which point the system was shut down, updated, and restarted In March 2002 The system
<br /> ran until January 2003, when it was shut down to allow for system modifications and
<br /> property development Although It was slated to go back online in July 2004, Its current
<br /> status can not be verified by SECOR
<br /> Groundwater samples collected in May 2004 contained concentrations of TPHg from below
<br /> the method detection limits to 340 pg/L The concentrations of MtBE ranged from below
<br /> the method detection limits to 370,000 µg/l- The concentrations of BTEX ranged from
<br /> below the method detection limits to 85,000 µg/L, 81,000 ptg/L, 5,200 µg/L, and 24,700
<br /> I µg/L, respectively
<br /> N 1FdeslProtectslChevronlRetaiil#9-61711Site conceptual Model\FINAt._CSM doc
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