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1 <br /> I <br /> 15 November 2005 <br /> AGE-NC Project No 05-1256 <br /> Page 2 of 7 <br /> surface water feature in the vicinity of the property is Walker Slough,located approximately'/2-mile <br /> south of the site A _ l &w i t 1p S <br /> The estimated depth to ground water at the property is approximately 30 feet below surface grade <br /> ' (bsg),based on the map entitled Lines of Equal Depth to Groundwater Spring 1999 published by the <br /> San Joaquin County Flood Control District and Water Conservation District(FCD&WCD) The map <br /> ' entitled Lines of Equal Elevation of Groundwater Spring 1999, also published by the FCD&WCD, <br /> shows the property to be in an area where ground water flows toward the east-southeast,but this may <br /> be modified by changing recharge and discharge patterns Ground water is considered to be of <br /> beneficial use and is used for domestic, industrial and commercial purposes <br /> ' 22 PREVIOUS INVESTIGATIONS <br /> In January 2001,dispensers and product lines at the subject facility were removed and replaced One <br /> ' soil sample was collected beneath each of four dispensers by Parker Environmental Services of <br /> Pittsburg, California, under the direction of EHD representatives The samples were collected at <br /> depths between 0 5 foot and 2 5 feet bsg and were identified as follows 1 @ 2-2 5', 2 @ 0 5-1', 3 <br /> ' @ 2-2 5', and 4 @ 2-2 5' The samples were submitted for laboratory analysis <br /> Total petroleum hydrocarbons quantified as gasoline(TPH-g)were reported in each soil sample at <br /> concentrations ranging from 770 milligrams per kilogram (mg/kg, equivalent to parts per million, <br /> ppm, sample 3 @ 2-2 5')to 10,000 ppm (sample 1 @ 2-2 5') Benzene,toluene, ethylbenzene, and <br /> total xylenes were reported in each sample at concentrations ranging from 0 64 mg/kg (toluene, <br /> ' sample 3 @ 2-2 5') to 1,300 mg/kg (xylenes, sample 1 @ 2-2 5') <br /> Methyl tertiary-butyl ether(MTBE)was reported in three of four soil samples at concentrations as <br /> high as 340 mg/kg(sample 2 @ 0 5-1') Tertiary-amyl methyl ether(TAME)was reported in two of <br /> four samples at concentrations as high as 15 mg/kg(sample 2 @ 0 5-1') DI-Isopropyl ether(DIPS), <br /> ethyl tertiary-butyl ether(ETBE), and tertiary-butyl alcohol (TBA)were not detected in any of the <br /> four samples collected and analyzed However, detection limits for all samples were raised due to <br /> matrix interferences <br /> 3.0. PROCEDURES <br /> The field work reported herein was performed in accordance with procedures outlined in the AGE- <br /> prepared Preliminary Site Assessment Work Plan, dated 15 April 2005 and approved by the EHD <br /> ' in a letter dated 05 May 2005 <br /> Advanced GcoEvironmenial,Inc <br />