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RECENED 2005 4t6 Quarter Groundwater Report ENVIROW41EN I l iE,' LTH • Frontier Transportation, Inc. PERMIT/SERVICES ' February 13, 2006 Page 1 ' 1.0) INTRODUCTION Biophysics Environmental Assessments, Inc (BEA)was contracted by Frontier ' Transportation, Inc to report the 2005 fourth quarter groundwater monitoring results at the Frontier Transport facility, 425 Larch Road, Tracy, California(See Figure 1, Site Location Map) The 2005 fouth quarter groundwater monitoring episode was performed on December 15, 2005 by Del-Tech Geotechnical Support Services The San Joaquin County Public Health Services, Environmental Health Division(PHS/EHD), Carrol Oz, Senior REHS requested quarterly groundwater monitoring on September 8, 1999 1 2.0) SITE LOCATION AND HISTORY The site is located in Tracy, Califorma 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 soil ' Vborings(B-1, B-2 B-3, MW.-IRA, MW-IRB, and MW-2RA) and one angle boring(B-4)to 14f 6 depths between' and tom' below grade surface (bgs)to assess subsurface conditions near the northeastern excavation In addition, two hand augers (S-I and S-2)were advanced to T bgs to assess subsurface conditions beneath the dispenser and product hues and three groundwater monitoring wells, MW-1 through MW-3, were drilled to approximately 25' bgs to assess the subsurface water beneath the site Initial subsurface water was encountered at 10 5'bgs Boring ' B-4 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 Groundwater samples were collected from monitoring wells MW-1, MW-2, and MW-3 on August 30, 1996 and April 21, 1997 by Twinning Results are presented in Table 1 I i i