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Project No 58100-06-62 <br /> August 22, 1996 <br />' Page 3 <br /> The samples were sealed, labeled and placed in an ice chest containing ice and were initially <br /> transported to Geocon's Sacramento office for cold storage at 4 degrees Celsius pending shipment to <br /> the analytical laboratory The samples were subsequently shipped to Advanced Technology <br /> ' Laboratories(ATL) located in Signal Hill, California, using standard chain-of-custody protocol <br /> ANALYTICAL METHODS AND RESULTS <br /> Laboratory Analysis <br /> The groundwater samples were delivered 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 of <br /> custody documentation are presented in Appendix B <br /> Analytical Results <br /> The highest petroleum hydrocarbon concentrations were detected within the vicinity of and <br /> downgradient to the former UST excavation at maximum reported concentrations of 51,000 ug/l <br /> TPHg, 2,600 ug/l TPHd and 10,100 ug/l benzene Concentrations of petroleum hydrocarbons in <br /> groundwater decreased away from the source area to below test method detection limits in perimeter <br /> cross gradient wells MW-4, MW-5, MW-9 and MW-12 Dissolved phase petroleum hydrocarbons <br /> were reported in downgradient perimeter well MW-11 at concentrations of 60 ug/l TPHg, 120 ug/1 <br /> TPHd and 5 1 ug/1 benzene <br /> 1 MTBE was detected in ten of the thirteen monitoring wells at concentrations ranging from 0 5 ug/l to <br /> 53 ug/l The highest MTBE concentration was detected in well VW-2, located within the source area, <br /> and decreased to 14 ug/l 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 Concentrations of <br /> petroleum hydrocarbons in groundwater are presented on Figure 3 Laboratory reports and chain-of- <br /> custody records are presented in Appendix B <br /> WORK IN PROGRESS <br /> ' Geocon is scheduled to perform a vapor extraction pilot test(VET) during the month of August 1996 <br /> The purpose of the VET will be to evaluate the feasibility and economics of using vapor extraction to <br /> remove gasoline hydrocarbons from beneath the site <br /> 1 <br /> 1 <br />