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I <br /> 21 January 1993 <br /> (GeoAudit CV 42F4-1 .68) <br /> Page 3 of 4 <br /> 5. 0 HYDROCARBON CONTAMINATION <br /> 5.1 Field Evidence <br /> All samples were field-screened with the PID immediately after <br /> extrusion from the sampler, and the readings were recorded on the <br /> boring logs. In general, there was little evidence of volatile <br /> organic contamination; PID readings were below 5 ppm in all borings <br /> except ® (Appendix A) . Samples at 20 , 30, and 35 feet in this <br /> boring emitted a slight odor of degraded hydrocarbons and had PID <br /> readings between 18 and 260 ppm. Quantitative laboratory analysis <br /> of these samples yielded much lower values (see below) . Hydrocarbon <br /> odors were not detected in other samples. <br /> 5.2 Laboratory Evidence <br /> A total of 22 samples were analyzed for Total Petroleum <br /> Hydrocarbons in the gasoline range (TPH-G) , volatile aromatic <br /> hydrocarbons (BTE&X) , and total lead. Samples were selected for <br /> anlaysis based on either field evidence of contamination (PID <br /> readings) or depth range. On average, three samples per well were <br /> analyzed. <br /> The laboratory, report and chain of custody , form are included in <br /> Appendix B. All samples have :total lead concentrations between 2 <br /> and 7. 5 mg/kl, and are within ' normal background levels for , <br /> inorganic lead. No samples from borings Bl, B2, B4 ,1 B5, or B6 <br /> contain petroleum hydrocarbons above the detection limits of 0. 50 <br /> mg/kg (ppm _ for gasoline or 0. 005 mg/kg for BTE&X compounds. <br /> Samples B 30 and 3-35 contained detectable amounts ' of <br /> ethylbenzene ( . 0082 and . 021 mg/kg) , confirming field evidence 'of ' <br /> faint, probably degraded hydrocarbons. Sample B3-35 was collected <br /> at the approximate soil/water interface. <br /> 16. 0 CONCLUSIONS AND RECOMMENDATIONS ' <br /> The �solil-vapor survey performed by Evax Technologies in 1990 has <br /> been! 'used to design a drilling, program to assess possible soil I <br /> contamination at this site. I `Soil borings were located in' areas j <br /> ! wher`e high levels of soil vapors,Iwerel(previously reporlted, as 'well f <br /> as �irn areas where vapors had note been detected. Na evidence of, �° ! <br /> I hydrocarbon contam�nation� ,wash detected l lin five Iof the six fborings I , <br /> drilled in this investigation, (Based on fiel" Il andsIlaboratory j <br /> !I results, it appears that most !of'the property, is riot contaminated. <br /> ! Very low levels of ethylbenzene contamination were detected on the <br /> Iwester,n edge of the property in boring B3 . This contamination <br /> prlob'ably represents the remnants of old gasoline contamination in <br /> I , I <br /> ri � rF, Til u�I���r,I rr <br />