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S E C 0 R
<br /> Ms. Vicky McCartney
<br /> September 15, 2003
<br /> Page 3
<br /> Freeze and Cherry, 1979), which consist of silt and silty sand underlain by fine to medium sand
<br /> (Alisto, 1995).
<br /> Between December 10 and 22, 1998, Gettler-Ryan Incorporated (G R) supervised the removal of two
<br /> 10,000 gallon USTs and one 8,000 gallon single-walled UST, dispensers, and associated product
<br /> dispenser piping. Laboratory analysis of soil samples collected from the UST excavation reported
<br /> maximum concentrations of TPHg at 31 ppm (3W), benzene at 0.27 ppm (3W), and,MtBE at 80 ppm
<br /> (3E). Laboratory analysis of soil samples collected from the beneath the dispensers and product
<br /> piping detected maximum concentrations o,rof watef TPHg at 1200 ppm (D1) and MtBE at 1.8 ppm (D3).
<br /> Additionally, approximately 115,000 galLonsr �_as removed from_the.,ex-cavation during the:
<br /> installation of the new�U.STs. Laboratory analysis of a grab groundwater sample reported maximum
<br /> concentrations of TPHg, benzene, and MtBE at 17,000 micrograms per liter (µg/L), 1,500 pg/L, and
<br /> 120,000 µg/L,_respectively. Groundwater Monitoring Well MW-1 was destroyed to allow the
<br /> enlargement of the existing UST excavation to allow for the installation of theen w USTs (GR, 1999). j
<br /> On October 7 and 8, 1999, Cambria Environmental Technology, Incorporated (Cambria) conducted
<br /> Cone Penetration Testing (CPT) by advancing six borings (CB-1 through CB-6) for 'soil and
<br /> groundwater sampling and two borings (CB-2E and CB-4E) for electric soil logging. Soil samples
<br /> were collected every five feet to approximately 20 feet bgs. Water samples were collected using a
<br /> hydropunch at depths of 16 and 29 feet bgsorings CB-1, CB-2, and CB-4 through CB-6. Water V� o�
<br /> samples were collected at depths of 16 and Yfeet bgs in boring CB-3. Laboratory analysis of soil 1z
<br /> samples collected from the soil borings detected maximum concentratio of gasoline range
<br /> organics (GRO) at 27 milligrams per kilogram (mg/kg) (CB-3-13.5);r`MtBE at 27 mg/kg (CB-3-13.5),
<br /> and Tert amyl methyl ether (TAME) at 0.058 mg/kg (CB-3-13.5). rBTEX was not detected above
<br /> laboratory detection limits. Laboratory analysis of groundwater samples collected from the soil
<br /> borings detected maximum concentrations of gasoline range organics (GRO) at 87,000 µg/L(CB-4-
<br /> 16HP), benzene at 1,300 pg/L (CB-4-16HP), MtBE at 38,000 µg/L (CB-1-16HP), and TAME at 160
<br /> gg/L (CB-1-16HP) (Cambria, 1999). 1/
<br /> Also in late 1999, Cambria conducted a sensitive�receptorsurvey. Based on a review of United
<br /> States Geological Survey (USGS) topographic maps and recent area maps, an unnamed levy:
<br /> restricted slough was identified within 2,000 feet.south..of�the site, and a man-made lard)kas`located
<br /> in a residential area-approximately 1,500_feet southwest of the site. Well logs obtained through the
<br /> State of California, Department of Water
<br /> Resources (DW R)indicated the presence of an irrigation
<br /> well owned by the California Department of Transportation (Cal-Trans), which was s6eene�rom
<br /> approximates 214 feet to 350 feet bgs and located approximately 315 feet west of the site (Cambria,
<br /> en de
<br /> 1999). According to Cambria, the Cal-Trans well had bestroyed in preparation for
<br /> reconfiguration of the Interstate 5 and Hammer Lane interchange (Cambria, 2000). According to Mr,
<br /> Witzak Gilon of the City of Stockton Municipal Water System (CSMWS), there were-no CSMWS
<br /> water supply wells located within the 2,000-foot search-radius,-(Cambria,-1-999).
<br /> On June 12 and 13, 2000, Cambria replaced destroyed Well MW-11 and damaged Well MW-2 with //s°
<br /> Groundwater Monitoring Wells MW-1 R and MW-2R to depths of 31.5 and 30 feet bgs, respectively. Al % k
<br /> In addition, Cambria drilled and installed two 2-inch diameter wells (MW-9 and MW-10) to a total
<br /> depth of 31.5 feet bgs./Laboratory analysis of soil samples collected from the soil borings detected k6
<br /> maximum concentrations of TPHg at 0.82 mg/kg (MWS-12') and MtBE at 2.6 mg/kg (MW8-30).
<br /> BTEX was not detected above laboratory detection limits./Laboratory analysis of groundwater
<br /> �! samples collected from all wells detected maximum concentrations of TPHg at 3,400 gg/L (VW-1),
<br /> 1AConocoPhil1ips\Tosco MarkeEing1111931Reports\Revised[RAP&WP.doc
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