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Y � <br /> I <br /> Frontier Transportation, Inc. <br /> Well Installation Work Plan <br /> November 14, 2006 <br /> Page 1 <br /> 1 .0) INTRODUCTION <br /> Biophysics Environmental Assessments, Inc. (BEA) was contracted by Frontier <br /> Transportation, Inc. (909-5904200) to prepare a work plan to delineate the extent of dissolved <br /> -' phase MTBE plume identified at 425 Larch Road, Tracy, California (See Figure 1 , Site Location <br /> _ Map). The proposed work will consist of the installation of two to three monitoring wells to <br /> total depths of twenty feet below grade surface. The additional wells were requested by the San <br /> Joaquin County Public Health Services, Environmental Health Division (EHD), by Victoria L. <br /> --� McCartney, Senior RENS. <br /> The EHD recommended installation of additional wells based on the results of the 2006 <br /> 3`d quarter groundwater monitoring results. Sampling results indicated migration of the <br /> contaminant plume to the west and to the north. Additional groundwater wells are proposed so <br /> that the contaminant plume can be accurately delineated. <br /> 2.0) SITE LOCATION AND HISTORY <br /> The site is located in Tracy California at 425 Larch Road in the northwest quarter of <br /> section 16, Township 2 South, Range 5 East, Mount Diablo Baseline at Meridian. The site <br /> consists of a trucking facility with one metal frame building and all parking and work areas <br /> ( I capped by cement and/or asphalt. The site is located in an industrial park. <br /> Six (6) underground fuel storage tanks (USTs), three diesel tanks located northeast of the <br /> terminal and three gasoline tanks located southeast of the terminal, were removed from the site <br /> - ' on July 21 , 1995 . Soil sample analysis identified total petroleum hydrocarbons as gasoline <br /> (TPH-g) and total petroleum hydrocarbons as diesel (TPH-d) in the gasoline tank excavation at <br /> 1 maximum concentrations of 9,800 mg/kg and 120 mg/kg, respectively. Groundwater sample <br /> analysis identified dissolved phase TPHd in the diesel excavation pit at a maximum <br /> Lconcentration of 1 ,200 µg/L. <br /> In August of 1996, Twinning Laboratories, Inc advanced six vertical soil borings (B-1 , B- i�z n <br /> 2, B-3. MW4RA, MW4RB, and MW-2RA) and one angle boring (B-4) to deptbs between 10:5' 9. S <br /> and,12. 'below grade (bgs) to assess subsurface conditions near the northeastern excavation. In <br /> addition, two hand augers (S- 1 and S-2) were advanced to 3 ' bgs to assess subsurface conditions <br /> beneath the dispenser and product lines and three groundwater monitoring wells, MW-L through <br /> MW-3, were drilled to approximately 25' bgs to assess the subsurface water beneath the site. <br /> Initial subsurface water was encountered at 10.5' bgs. Boring B-4 located northwest of the <br /> 'i former USTs identified maximum TPH-g, BTEX (Benzene, Toluene, Ethylbenzene, Xylene), <br /> and MTBE (MethyMert Butyl Ether) as 1 ,300 µg/kg, 180.7 µg/kg, and 110 µg/kg, respectively at <br /> II <br />