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S E C O R - ConocoPhillips 2705445 January 15, 2007 �i �' ?rot Page 2 ENVIRONNII W HEALTH PERIMITiSLERVICES to 47 feet bgs and groundwater samples were collected. Permits from San Joaquin County Environmental Health Department were obtained for each boring and are included as Attachment A. SECOR's geologist logged the soil types encountered in the borings on the boring logs in accordance with the Unified Soils Classification System (USCS)visual and manual methods. Upon completion of drilling, the borings were filled to the surface with cement grout using a tremie pipe, and the surface was finished with concrete to match existing conditions. Subsurface Conditions Soil in the borings primarily consisted of clay from approximately 2 to10 feet below ground surface (bgs) underlain by silt and silty sand with lenses of sand. The boring logs are provided in Attachment A. Soil conditions are described on the boring logs, provided in Attachment B. Borings B-7 and B-11 were drilled to groundwater and the static groundwater level was measured to depths of 46 to 47 feet bgs. Laboratory Analytical Procedures Soil and groundwater samples collected during field activities were delivered under chain-of-custody protocol to Severn Trent Laboratories of Pleasanton, California (STL). STL is certified by the State of California Department of Health Services Environmental Laboratory Accreditation Program to perform the requested analyses. Soil samples collected from borings B-7 through B-11 were analyzed for gasoline range organics (GRO), diesel range organics (DRO), benzene, toluene, ethylbenzene, and total xylenes (BTEX), and fuel oxygenates methyl tertiary butyl ether (MTBE), tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), ethylene dibromide (EDB), 1,2-dichloroethane(1,2-DCA),tertiary amyl methyl ether(TAME),and ethanol by EPA Method 82608. Groundwater samples collected from borings B-7 and B-11 were analyzed for TPHd, TPHg, BTEX and fuel oxygenates, MTBE, TBA, DIPE, ETBE, EDB, 1,2-DCA, TAME, and ethanol by EPA Method 8260B. Summary of Laboratory Analytical Results Laboratory analytical data for soil samples collected during this investigation are summarized in .Table 1. Laboratory analytical data for groundwater samples collected during this investigation are summarized in Table 2. Analytical reports and chain-of-custody records are provided in Attachment C. Laboratory analytical results for soil samples collected during this investigation indicate the following: • GRO (8,800 mg/kg), DRO (32mg/kg), and benzene (25mg/kg)were reported only in the soil sample collected from boring B-7 at 20 bgs. • MTBE was reported in the soil samples collected from borings B-8, B-7, and B-11 at concentrations ranging from of 0.022 mg/kg (B-8@40') to 8.0 mg/kg (B-11 @50'). • Organic vapors were measured in all soil samples collected from the borings using a phono-ionization detector(PID). Organic vapor measurements ranged from 0 to greater than 2,000 parts per million (ppm). hConocoPhillipsOue Diligence127054451report\2705445 Due Diligence report.doc