SITE INFORMATION AND CORRESPONDENCE_FILE 1

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Chevron Chevron P: SEP 3 0- P;: 12: 5 9 Chevron Pipe Line Company September 27, 1994 Western Business Unit 5080 California Avenue,Suite 400 Bakersfield,CA 93309-1671 Ms. Wendy Cohen California Regional Water Quality Control Board Central Valley Region 3443 Routier Road, Suite A California Environmental Protection Agency Sacramento, California 95872-3098 MEETING OF SEPTEMBER 23, 1994 DIVIDEND PROPERTY,TRACY,CALIFORNIA Dear Ms. Cohen: On behalf of Chevron Pipe Line (CPL), and all other related parties, it was a pleasure meeting with you and Mr. Moody at your office last Friday(September 23, 1994) to discuss the CPL'S Dividend Property project. The meeting was both informative and enjoyable. This letter confirms our discussion of several points. 1) During the discussion of the recent quarterly monitoring report submitted by Geomatrix Consultants Inc. (Geomatrix), dated September 12, 1994, there was a concern expressed by the Regional Water Quality Control Board (RWQCB) how petroleum hydrocarbons, as reported by the laboratory as total petroleum hydrocarbons (TPH) as crude oil, could be detected in groundwater samples, yet not be "dissolved" in groundwater. As presented by Geomatrix, the chromatograms from the TPH analysis for groundwater samples indicated that the hydrocarbons measured by the laboratory consisted of long chain, late-boiling petroleum hydrocarbons and non-petroleum hydrocarbons which are likely natural byproducts of biodegredation. Both Geomatrix and Chevron Research and Technology Center (CRTC) believe that the physical properties of these constituents are such that they are virtually insoluble in water. If there were late-boiling, long chain petroleum hydrocarbons present as dissolved phase in 1 ' 4 l) ' detected 1• 11 TT 1 1 groundwater at this site,they sl'iGu,u �e ue�2Gted ir, down gradient wc��s. nowcvee, grounuwater sariip,c;s from the downgradient monitoring wells at this site generally do not contain detectable concentrations of TPH. A possible mechanism that resulted in the detection of TPH during the last round of groundwater sampling is that the hydrocarbons were sorbed onto micron-sized soil particles that were introduced into the well during purging and sampling activities. We understand the need for further research and clarification of this mechanism. Published documentation and further explanations on this subject will be forwarded to you. 2) In order to better document and track the groundwater monitoring activities, you suggested that the RWQCB issue a formal request for quarterly monitoring at the Dividend Property. The request will require quarterly groundwater monitoring for a period of one year. Unless informed otherwise, CPL is assuming that the last round of sampling,performed in August 1994, is included in the one year period.