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k Aquifer Pump Test Report of Findings Frontier Transportation, Inc. November 8, 2006 Page 1 1 .0) INTRODUCTION it Biophysics Environmental Assessments, Inc . (BEA) was contracted by Frontier Transportation, Inc. to prepare a report of findings for the installation of MW-22 and MW-23 and the subsequent aquifer pump test performed at the Frontier Transport facility located at 425 Larch Road, Tracy, California (See Figure I for site location) . The San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD), Vicki McCartney, EHS approved the additional site assessment on August 28 , 2006. Monitoring wells MW-22 and MW-23 were installed on September 26, 2006 to be used as observation wells. The aquifer pump test was performed at MW-3R on October 13 , 2006. 2.0) SITE LOCATION AND HISTORY The site is located in Tracy, California at 425 Larch Road in the northwest quarter of section 16, Township 2 South, Range 5 East, Mount Diablo Baseline at Meridian. The site consists of a trucking facility with one metal frame building and all parking and work areas capped by cement and/or asphalt. The site is located in an industrial park. Six (6) underground fuel storage tanks (USTs), three diesel tanks located northeast of the terminal and three gasoline tanks located southeast of the terminal, were removed from the site on July 21 , 1995 . Soil sample analysis identified total petroleum hydrocarbons as gasoline (TPH-g) and total petroleum hydrocarbons as diesel (TPH-d) in the gasoline tank excavation at maximum concentrations of 9, 800 mg/kg and 120 mg/kg, respectively. Groundwater sample analysis identified dissolved phase TPH-d in the diesel excavation pit at a maximum concentration of 1 ,200 pg/L. In August of 1996, Twinning Laboratories, Inc. (Twinning) advanced six vertical soilborings (B- 1 , B-21 B-3 , MW- 1 RA, MW- 1RB, and MW-2RA) and one angle boring (B4) to depths between 10.5' and 12. 5' below grade surface (bgs) to assess subsurface conditions near the northeastern excavation. In addition, two hand augers (S- 1 and S-2) were advanced to T bgs to assess subsurface conditions beneath the dispenser and product lines and three groundwater monitoring wells, MW- 1 through MW-3 , were drilled to approximately 25' bgs to assess the subsurface water beneaththe site. Initial subsurface water was encountered at 10. 5 ' bgs. Boring B4 located northwest of the former USTs identified maximum TPH-g, BTEX (Benzene, Toluene, Ethylbenzene, and Xylene), and MTBE (Methyl-tert Butyl Ether) as 1 ,300 mg/kg, 180.7 mg/kg, and 110 mg/kg, respectively at 10.2' bgs.