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Project No S8100-06-62 <br /> ' June 18, 1996 <br /> Page 3 <br /> ' Following well recovery, a water sample was collected from each well using disposable bailers and <br /> decanted into four 40-m1 volatile organic analyses vials and one one-liter amber bottle The samples <br /> were sealed, labeled and placed in an ice chest containing ice and were initially transported to <br /> ' Geocon's Sacramento office for cold storage at 4 degrees Celsius pending shipment to the analytical <br /> laboratory The samples were subsequently shipped to Advanced Technology Laboratories (ATL) <br /> located in Signal Hill, California, using standard chain-of-custody protocol <br /> ANALYTICAL METHODS AND RESULTS <br /> ' Laboratory Analysis <br /> The groundwater samples were deliverer)to ATL, for the analyses of TPHg and TPHd following EPA <br /> ' Test Method 8015 modified, benzene,toluene, ethylbenzene and total xylenes (BTEX) following EPA <br /> Test Method 8020 and MTBE following EPA Test Method 8020 The laboratory reports and chain <br /> of custody documentation are presented in Appendix B <br /> ' Analytical Results <br /> The highest petroleum hydrocarbon concentrations were detected within the former UST excavation <br /> (VW-2) at reported concentrations of 54,000 ug/l TPHg and 8,100 ug/l benzene Concentrations of <br /> petroleum hydrocarbons in groundwater decreased away from the source to below test method <br /> detection limits with the exception of 100 ug/1 TPHd in MW-12 and 50 ug/1 TPHg in MW-5 Benzene <br /> concentrations in the perimeter wells ranged from below detection to 0 7 ug/l The distribution of <br /> gasoline and diesel range hydrocarbons in groundwater is currently bounded by perimeter wells MW- <br /> 5, MW-9, MW-11, and MW-12 <br />' MTBE was detected in ten of the thirteen monitoring wells at concentrations ranging from 0 6 ug/l to <br /> 60 ug/1 The highest MTBE concentration was detected in VW-2, located within the source area, and <br />' decreased to 1 0 ug/1 in perimeter well MW-11, which is the farthest well from the source area <br /> A summary of the analytical laboratory test results is presented on Table I Laboratory reports and <br /> chain-of-custody records are presenter)in Appendix B <br /> 1 <br />