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APPENDIX B: <br /> ' PREVIOUS ENVIRONMENTAL ACTIVITIES <br /> 1977-1978. The property owner performed limited soil excavation within the western portion of <br /> the Tracy Pump Station site based on observations of affected soil. The property owner scarified <br /> approximately 12 acres of the western portion of the property. During this activity,affected soil <br /> was encountered and removed from the site. Thirty-eight truck loads of soil and some piping <br /> were removed. The soil was excavated to an approximate depth of 5 feet in the excavated areas. <br /> The specific area where the excavation occurred is not known. The 12-acre portion of the <br /> property is currently in use for alfalfa farming. <br /> August 2002 Investigation.' Geomatrix Consultants, Inc. advanced 17 soil borings (TS-01 <br /> through TS-17) at locations that targeted former pump-station facilities and the former pipeline <br /> areas. Three soil samples were collected from each boring at depths that ranged between 2 and <br /> 31 feet below ground surface (bgs). Soil samples were submitted for chemical analyses of total <br /> ' petroleum hydrocarbons quantified as crude oil (TPHc)by United States Environmental <br /> Protection Agency(EPA) Method 80I5 Modified;benzene, toluene, ethylbenzene, and total <br /> xylenes(BTEX)by EPA Method 826013; and polynuclear aromatic hydrocarbons (PAHs)by <br /> ' EPA Method 8270C with selective ion monitoring(SIM). Ethylbenzene was detected in one soil <br /> sample at a concentration of 0.033 milligrams per kilogram(mg/kg). Seventeen soil samples <br /> contained detectable TPHc at concentrations ranging from 110 mg/kg to 60,000 mg/kg. Toluene <br /> ' was detected in 24 soil samples at concentrations ranging from 0.005 mgfkg to 0.15 mg/kg. <br /> PAH compounds were detected in 14 soil samples at concentrations ranging between <br /> 0.005 mg/kg to 92 mg/kg. The highest concentrations of TPHc and PAHs were detected in the <br /> ' soil sample collected at 3 feet bgs near the former blow-off pond, located northwest of the <br /> former pump station. <br /> ' Depth to first-encountered groundwater in the borings ranged from 4.5 to 16.5 bgs. Grab <br /> groundwater samples were collected from 10 borings. The samples were analyzed for TPH <br /> quantified as gasoline(TPHg), and as diesel (TPHd)with and without silica-gel preparation by <br /> EPA Method 8015 Modified; BTEX by EPA Method 8260B; and PAHs by EPA Method 8270C <br /> SIM. TPHg, benzene, and ethylbenzene were not detected in any of the grab groundwater <br /> samples analyzed. Seven of the 10 grab groundwater samples analyzed contained detectable <br /> ' TPHd concentrations ranging between 100 micrograms per liter(µg/L) and 1,600 µg/L. PAHs <br /> were detected in three of the 10 grab groundwater samples analyzed. Total xylenes were <br /> detected in two grab groundwater samples and toluene was detected in one sample. The highest <br /> ' dissolved-petroleum concentrations were detected from groundwater collected near the former <br /> blow-off pond. <br /> February 2004 Investigation.2 SAIC Energy, Environment & Infrastructure, LLC (SAIL) <br /> observed Gregg Drilling and Testing, Inc. (C57#485165)advance 13 soil borings (SB-1 through <br /> SB-13)to evaluate the lateral extent of affected groundwater beneath and down gradient of the <br /> site. The Central Valley Regional Water Quality Control Board(RWQCB) reviewed the work <br /> 1 plan, and in a November 2003 letter to Chevron Environmental Management Company <br /> 1. Geomatrix Consultants,Inc.,2002. Soil and Groundwater Investigation Report,Former Pump Station(San Joaquin County), <br /> Tracy, California. November. <br /> 2. SAIL,2004_ Groundwater Investigation Report at Former Tracy Pump Station, 14821 West Grant Line Road, Tracy, <br /> California. May. <br /> ' B-1 <br /> SAIE <br /> 1 <br />