ARCHIVED REPORTS XR0008696 - Laserfiche WebLink

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a Tosco Corporation,A Subsidiary of Phillips Petroleum Company lune 21 2002 Tosco Service Station No 4409 1502 El Dorado Street Stoekton CA On August 30, 31, and September 5, 2001, IT Installed three additional on-site deep groundwater monitoring wells (MW-8 through MW-10) at locations upgradient of the UST complex, in the vicinity of the pump Islands and downgradient of the pump Islands Wells were completed at depths of 79 feet (MW-8) and 80 feet bgs (MW-9 and MW-10) Petroleum hydrocarbons were present in soil samples collected between 60 and 80 feet bgs, with concentrations of TPHg and benzene reported up to 4,400 mg/kg and 77 mg/kg, respectively TPHg was detected in wells MW-8 through MW-10 at concentrations up to 22,000 ug/l, and benzene was detected in wells MW-9 and MW-10 at concentrations up to 600 ug/l Fuel oxygenates were not detected in any soil and groundwater samples collected from the site Based on the results of this investigation, SECOR recommended the Installation of additional off-site deep zone groundwater monitoring wells for further delineation of the dissolved petroleum hydrocarbon plume between approximately 60 feet and 80 feet bgs (SECOR, May 29, 2002) PROPOSED SCOPE OF WORK Four off-site wells are proposed to delineate the downgradlent extent of the dissolved petroleum hydrocarbon plume in the deeper water-bearing zone The proposed locations are shown on Figure 2 The specific scope of work Is discussed below • Site Safety Plan. As required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910 120), and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (CCR Title 8, Section 5192), SECOR will prepare a site-specific Health and Safety Plan (HASP) prior to the commencement of fieldwork The site-specific HASP will be reviewed by the field staff and contractors prior to the commencement of field operations at the site, and is included as Attachment A • Permitting Encroachment permits will be obtained for three of the four proposed well locations An access agreement will be obtained for one well location proposed on private property Following the receipt of the encroachment permits and the access agreement for the proposed well locations, well installation permits will be obtained from the SJCEHD • Groundwater Monitoring Wells. Soil borings for monitoring wells will be drilled using 8-inch diameter hollow-stem augers Upon completion of drilling, a 2-inch diameter groundwater monitoring well will be Installed in each boring The wells will be screened from approximately 70 feet to 80 feet below ground surface (bgs), and completed at approximately 80 feet bgs Field procedures for the I\Tosco Markettng\4409\Work P1ans\Addrnonal Assessment WP doc