SITE INFORMATION AND CORRESPONDENCE_FILE 1

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GEOMATRIX Mr. Don O. Culbertson Chevron Pipe Line Company 8 March 1995 Page 7 and TRPH at wells MW-13, MW-23, MW-24, which are screened across crude oil- affected soil, and MW-22 during the next quarterly monitoring event to evaluate the success of this technique in removing the non-dissolved fraction. Further, we will instruct the laboratory to perform a silica gel cleanup on the filtered samples to be analyzed for TPH to mitigate the effects of soluble non-PHCs influencing the Method 8015 result. Silica gel cleanup is required for Method 418.1. Samples collected for BTEX and PNA analyses will not be field-filtered or subject to silica gel cleanup. If BTEX and PNAs are non-detect and TPH or TRPH (filtered) shows detections, this would suggest that 1) the field filtration is not capable of removing all of the non-dissolved portion and/or 2) the sample contains soluble non-PHCs (biogenic materials) that are being measured by the TPH or TRPH analysis and are not being removed by the silica gel cleanup. We will review the chromatograms to evaluate the cause for the TPH detections. Detections of TRPH will be further analyzed by GC/MS on selected TRPH extract(s) to identify soluble non-PHCs such as microbial lipids or fatty acids. We believe, based on the discussion presented herein, that results from such analyses will provide a more accurate assessment of dissolved- phase PHC concentrations and the potential for transport of PHCs in groundwater at the site. Please call me at any time to discuss this information. We look forward to your response and the application of this approach at the Dividend property. Sincerely, GEOMATRIX CONSULTANTS, INC. Dawn A. Zeo, C.E.G Senior Hydr6geolegist DAZ\lam CONT\C2677TPH.LTR Attachments: References Table 1 - Figures cc: Karen Svnowiec - Chevron Research and Technology Company