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Appendix B:Previous Environmental Investigations <br /> VERNALIS PUMP STATION <br /> Science Applications International Corporation (SAIC) 2005 Site Investigation? <br /> Gregg Drilling,under the supervision of SAIC, advanced six soil borings (SB-22 through SB-25, <br /> SB-30, and SB-36) and installed three monitoring wells (MW-5 through MW-7)between May <br /> 16 and 24, 2005, to further assess the extent of crude-oil affected soil and groundwater. The <br /> borings were advanced to depths ranging from 40 to 71.5 feet bgs, and soil and groundwater <br /> samples were collected from each location. Soil samples were analyzed for TPHc, BTEX, and <br /> PAHs. Groundwater samples were analyzed for TPHd, BTEX, and PAHs. <br /> TPHc were detected in soil in two of the eight borings. The two TPHc concentrations in soil <br /> above Environmental Screening Levels (ESLs)were 330 mg/kg(SB-22 at 1 foot bgs) and <br /> 380 mg/kg (SB-23 at 1 foot bgs). BTEX constituents or PAHs were not detected above ESLs or <br /> PRGs in the soil samples. <br /> TPHd concentrations above the WQOs ranged from 560 gg/L (SB-23) to 780 µg/L (SB-22). <br /> Benzene was detected in boring SB-22 at a concentration of 0.5 gg/L. All other BTEX <br /> constituents and PAHs were not detected in groundwater. <br /> SAIC 2008 Annual Groundwater Monitoring and Sampling9 <br /> SAIC performed groundwater monitoring, sampling, and reporting between 2005 and 2008. <br /> SAIC conducted groundwater monitoring and sampling of MW-2, MW-3, MW-5, MW-6, and <br /> MW-7 in July 2008. The COPCs were reported at non-detect concentrations in MW-2 and <br /> MW-7 with the exception of TPHd detected in MW-7 at a concentration of 390 gg/L. <br /> The Central Valley Regional Water Quality Control Board(RWQCB)reviewed the results of <br /> groundwater monitoring and sampling activities, agreed that adequate groundwater monitoring <br /> data had been collected from the site, and concurred that monitoring wells could be properly <br /> destroyed10. The Central Valley RWQCB also requested that an HHSE be prepared and <br /> submitted for the site. <br /> SAIC 2009 Monitoring Well Destructionll <br /> SAIC supervised the destruction of monitoring wells MW-1 through MW-5 in May 2009. The <br /> condition of each well was inspected prior to destruction. The total depth of each well was <br /> measured and compared to the well construction logs. RSI Drilling removed the monument <br /> casing and wellhead, and over-drilled each well using a CME-75 truck-mounted drill rig with <br /> 8-inch-diameter, hollow-stem augers. The sand pack and seal were removed by over drilling to <br /> total depth. The bore holes were backfilled via tremie pipe with neat cement from total depth to <br /> approximately 2 to 3 feet bgs, and topped with native soil to ground surface. <br /> 7. SAIC,2006. Soil and Groundwater Investigation Report, Vernalis Pump Station, Vernalis, California. August. <br /> 8. RWQCB-SF Bay,2008,Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater(Interim <br /> Final). May. <br /> 9. SAIC,2008. Second Semi-Annual 2008 Groundwater Monitoring and Sampling Report, Vernalis Pump Station, 35500 Welty <br /> Road, Vernalis, California. September. <br /> 10. RWQCB-Central Valley,2008. Review—2nd Semi-Annual 2008 Groundwater Sampling and Monitoring Report,Vernalis <br /> Pump Station,35500 Welty Road,Vernalis,San Joaquin County. November 21. <br /> 11. SAIC,2009. Groundwater Monitoring Well Destruction Report, Vernalis Pump Station, 35500 Welty Road, Vernalis, <br /> California. August. i <br /> B-3 SAIC. The Benham Companies.LL[ <br /> A Wholly Owned Subsidiary <br /> From&Axe to SolarAm <br />