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Ms. Kaite Hower GEOMATRIX <br /> Chevron Pipe Line Company <br /> 11 December 1996 <br /> Page 3 <br /> Assessment Results <br /> Field evidence of petroleum hydrocarbons was not observed during drilling and sampling of boring <br /> SB-l. The chromatograms generated from the GC analysis were evaluated for the presence of <br /> crude/Bunker C oil by comparing them to the GC chromatogram generated from a crude oil that is <br /> representative of the crude/Bunker C oil previously carried in the pipelines. The GC analysis indicated <br /> that petroleum hydrocarbons were not present in the soil samples collected at 10 and 15 feet bgs. The <br /> GC analysis indicated a small amount of heavy organic material (C20 to C40.,) was present in the soil <br /> sample collected at 4 feet bgs. The laboratory indicated the material did not match the crude oil <br /> standard. To aid in the identification of this material, the sample extract was cleaned with silica gel and <br /> reanalyzed. Biogenic material present from a variety of natural sources is difficult to distinguish by GC <br /> from petroleum hydrocarbons; and if not removed will appear as petroleum hydrocarbon during a GC <br /> analysis resulting in overstated or false positive results. A silica gel cleanup will remove a substantial <br /> amount of the biogenic material without removing the petroleum hydrocarbons, thus improving the <br /> reliability of the analytical results. The organic material was removed by the silica gel and the resulting <br /> concentration was less than the method detection limit (5 mg/kg) for TEH-C, indicating that the <br /> material present was not petroleum hydrocarbons. Based on the results of the fingerprinting (no <br /> petroleum hydrocarbons present), and in accordance with the work plan, BTEX and PAHs were not <br /> analyzed. <br /> Discussion <br /> Petroleum hydrocarbons were not observed in soil at the site during this or the previous assessment. <br /> Crude oil/Bunker C oil was not present in samples collected and analyzed during this assessment. <br /> These results indicate that the previous analytical results (ASE, 1995) are not representative of <br /> petroleum hydrocarbons and instead represent biogenic material. The results of these assessments <br /> demonstrate that this property is not affected by residual petroleum carried in the former pipeline. <br /> Based on these results, no further soil or groundwater assessment is necessary at this site. <br /> Please call if you have any questions. <br /> Sincerely yours, <br /> GEOMATRIX CONSULTANTS, INC. <br /> 14ceological <br /> rson &9Zemo,C.E.G. <br /> roj Engineer Principal Hydrogeologist <br /> Attachments <br /> 1APR0JEC7\C7499U499-MDOC <br />