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