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No petroleum hydrocarbons were detected in water samples from MW-8 or EW-1 during <br /> the June, September or December 1994 samplings This indicates a dramatic decrease in , <br /> petroleum hydrocarbons since 1988 The process of vapor extraction in the vicinity of these , <br />' wells, combined with natural degradation is most likely responsible for the sharp decrease <br /> in petroleum hydrocarbons Concentrations of toluene and xylenes ,lust above reporting <br /> limits were detected in the sample from MW-9 during the June 1994 sampling. However, <br />' hydrocarbons were not detected during the September or December 1994 samplings <br /> Concentrations of all contaminants detected during the June 1994 sampling were below the <br /> State of California Action Level (AL) and Maximum Contaminant Levels (MCLS) for <br />' drinking water <br />' 5.2 Hydrocarbon Impacted Soil <br /> The PHS/EHD stated in the October 5, 1994 letter that soil "contamination remaining is a <br /> threat to groundwater and further remediation is required " A narrow band of hydrocarbons <br />' was encountered from 30 to 40 feet in the confirmatory borings drilled on June 14, 1994 <br /> (CB-1 and CB-2) TPH as gasoline was detected in borings CB-1 and CB-2 at concentrations <br /> up to 2,200 ppm. However, no benzene was detected in any of the samples analyzed, and <br /> only low concentrations of toluene, ethylbenzene and xylenes were detected Therefore, the <br /> majority of the most mobile fractions of hydrocarbons has been remedXated The boring <br /> proposed across Sierra Nevada Street will also be used to assess the lateral extent of <br />' impacted soil. <br /> We recommend the use of a modeling program to determine the potential for hydrocarbons <br /> to impact groundwater Further soil remediation may be based on the results of this <br /> procedure <br /> 6.0 LIMITATIONS <br /> tOurP rofessional services were performed using that degree of care and skill ordinarily <br /> exercised by environmental consultants practicing in this or similar localities The findings <br /> were based upon analytical results provided by an independent laboratory Evaluations of <br /> the geologic/hydrogeologic conditions at the site for the purpose of this investigation are <br /> made from a limited number of available data points (i a monitoring wells) and subsurface <br /> 1 conditions may vary away from these data points No other warn anty, expressed or implied, <br /> is made as to the professional recommendations contained in this report <br /> 1 <br /> 1 <br /> o.,w.B.l:y oA7n2 Wn i <br />