ARCHIVED REPORTS XR0006615 - Laserfiche WebLink

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Tosco Corporation a subsidiary of Plulhps Petroleum Company 2 Tosco Station#11192, 1403 Counhy Club Lane,Stockton,CA March 4,2002 • In April 2001, GR conducted a subsurface investigation by advancing eight off site and two on site Geoproberm borings and one Cone Penetration Test(CPT) Laboratory analysis for soil samples submitted did not detect gasoline range total petroleum hydrocarbons (TPHg), benzene, toluene, ethylbenzene, total xylenes (collectively BTEX), or MtBE above laboratory detection limits Analyses of grab groundwater samples collected from boring CPT-1 at 75 feet below ground surface (bgs) reported maximum concentrations of MtBE at 120 parts per billion (ppb) TPHg and BTEX were not detected above laboratory detection limits in any grab groundwater sample analyzed (GR, 2001) In April 2001, GR conducted a well search in a i/2 mile radius of the site Three municipal wells were identified, with the closest being approximately 100 feet north- northwest of the site (GR, 2001) Between August 8 and 10, 2001, GR installed three two-inch diameter off site groundwater monitoring wells (MW-8 through MW-10) and one two-inch diameter on site groundwater monitoring well (MW-11) Wells MW-8 through MW-10 were installed to depths from 28 feet to 29 feet bgs Well MW-11 was installed to a total depth of 79 feet bgs with an 8 5 inch steel conductor casing extending from approximately 1 foot bgs to 53 feet bgs Laboratory analysis for soil samples submitted detected MtBE in one sample(MW-II at 14 feet bgs) at a concentration of 17 parts per million (ppm) TPHg, BTEX, Di-isopropyl ether(DIPE), tertiary-Amyl methyl ether (TAME), Ethyl tertiary-butyl ether(EtBE), and tert-ButyI alcohol (TBA)were not detected above laboratory detection limits Laboratory analysis for groundwater samples submitted detected MtBE in one sample (MW-11) at a concentration of 110 ppb TPHg, BTEX, DIPE, TAME, EtBE, and TBA were not detected above laboratory detection limits in any groundwater samples analyzed (GR, 2001) DPE OPERATION Pre-Test Activities Prior to initiation of field activities, SECOR obtained authorization to perform the DPE test from San Joaquin Valley Unified Air Pollution Control District SECOR also prepared a site-specific Health and Safety Plan (HASP) The HASP is required by the Occupational Health and Safety Administration (OSHA) "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) The Health and Safety Plan was reviewed by field staff and contractors prior to the beginning of field operations at the site DPE Summary SECOR performed DPE at the site on December 3rd through December 7th, 2001 DPE was performed using a 20 hp liquid nng vacuum pump connected to a H2 Oil Thermal Oxidizer(Therm-ox) for treatment of the extracted soil vapors prior to discharge to the