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S ECC R
<br /> Ms Victoria L McCartney
<br /> • March 3, 2005
<br /> Page 3
<br /> to 8 68x10 centimeters per second (cm/s) were within the lower range of expected K
<br /> values associated with the soli types encountered beneath the site (1 to 1x10-5 cm/s,
<br /> Freeze and Cherry, 1979), which consist of silt and silty sand underlain by fine to medium
<br /> sand (Alisto, 1995)
<br /> Between December 10 and 22, 1998, Gettler-Ryan Incorporated (GR) supervised the
<br /> removal of two 10,000-gallon USTs and one 8,000-gallon single-walled UST, dispensers,
<br /> and associated product dispenser piping Laboratory analysis of soil samples collected
<br /> from the UST excavation Indicated maximum concentrations of TPHg at 31 ppm (3W),
<br /> benzene at 027 ppm (3W), and methyl tertiary butyl ether (MtBE) at 80 ppm (3E)
<br /> Laboratory analysis of soil samples collected from the beneath the dispensers and product
<br /> piping detected maximum concentrations of TPHg at 1,600 ppm (D1) and MtBE at 1 8 ppm
<br /> (133) Additionally, approximately 15,000 gallons of water was removed from the excavation
<br /> during the installation of the new USTs Laboratory analysis of a grab groundwater sample
<br /> reported maximum concentrations of TPHg, benzene, and MtBE at 17,000 micrograms per
<br /> liter (jtg/L), 1,500 lig/L, and 120,000 pg/L, respectively Well MW-1 was destroyed to allow
<br /> the enlargement of the existing UST excavation for the installation of the new USTs (GR,
<br /> 1999)
<br /> On October 7 and 8, 1999, Cambria Environmental Technology, Incorporated (Cambria)
<br /> conducted a Cone Penetration Testing (CPT) investigation by advancing six borings (CB-1
<br /> through CB-6) for soil and groundwater sampling and two borings (CB-2E and CB-4E) for
<br /> electric soil logging Water samples were collected using a hydropunch at depths of 16 and
<br /> 29 feet bgs in borings CB-1, CB-2, and CB-4 through CB-6 Water samples were collected
<br /> at depths of 16 and 29 feet bgs In boring CB-3 Laboratory analysis of soil samples
<br /> collected from the soil bonngs detected maximum concentrations of gasoline range
<br /> organics (GRO) at 27 milligrams per kilogram (mg/kg, CB-3-13 5), MtBE at 27 mg/kg (CB-3-
<br /> 13 5), and tertiary amyl methyl ether (TAME) at 0 058 mg/kg (CB-3-13 5) Benzene,
<br /> toluene, ethylbenzene and total xylenes (BTEX) were not detected above laboratory
<br /> detection limits Laboratory analysis of groundwater samples collected from the soil borings
<br /> confirmed maximum concentrations of GRO at 87,000 µglL (CB-4-16HP), benzene at 1,300
<br /> µg/L (CB-4-16HP), MtBE at 38,000 µg/L (CB-1-16HP), and TAME at 160 gg/L (CB-1-16HP)
<br /> (Cambria, 1999)
<br /> Also In late 1999, Cambria conducted a sensitive receptor survey Based on a review of
<br /> United States Geological Surrey (USGS) topographic maps and recent area maps, an
<br /> unnamed levy-restricted slough was identified 2,000 feet south of the site, and a man-made
<br /> lake was located In a residential area approximately 1,500 feet southwest of the site Well
<br /> logs obtained through the State of California, Department of Water Resources (DWR)
<br /> indicated the presence of an irrigation well owned by the California Department of
<br /> Transportation (Cal-Trans), which was screened from approximately 214 feet to 350 feet
<br /> bgs, and located approximately 315 feet west of the site (Cambria, 1999) According to
<br /> Cambria, the Cal-Trans well had been destroyed In preparation for reconfiguration of the
<br /> Interstate 5 and Hammer Lane Interchange (Cambria, 2000) According to Mr Witzak Gllon
<br /> of the City of Stockton Municipal Water System (CSMWS), there were no CSMWS water
<br /> • supply wells located within the 2,000-foot search radius (Cambria, 1999)
<br /> 11ConocoPhdlipslRetail Sites1111931QMR14QMR04 Final doc
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