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Earth Systems Consultants Northern California 47853 Warm Springs Blvd. Fremont, CA 94539-7400 (510) 353-0320 Fax(510) 353-0344 File No. NFE-4463-04 Doc. No. 9908-085 August 23, 1999 MacKenzie/Ridgeway Partnership 240 Newport Center#231F Newport Beach, California 92660 Attention: Mr. Tod Ridgeway Subject: Old Byron Road between Corral Hollow Road and West 11th Street Tracy, California CHEVRON RIGHT-OF-WAY RELOCATION PRELIMINARY ASSESSMENT SOIL SAMPLING L Dear Mr. Ridgeway: Earth Systems Consultants Northern California(ESCNC)is submitting the methods and results of Lthe preliminary assessment soil sampling conducted along Old Byron Road between Corral Hollow Road and West I Vh Street (Figure 1). The investigation was directed by Chevron Pipe Line LField Company (CPL) to relocate the CPL right-of-way, located on the south side of Old Byron Road. Work On July 29, 1999, an ESCNC geologist supervised the advancement of six soil borings (EBI C; through EB6) using a drill rig operated by Exploration Geoservices, Inc. (C57 484288). The borings were drilled to depths ranging from 13.5 to 16.5 Piet below ground surface (bgs) at the locations shown on Figure 2. The boring locations were determined by CPL, and the majority of ! the field work was overseen by Mr. Lange Jorstad of Geomatrix Consultants (Geomatrix), the consultant for CPL. Soil from each of the borings was observed and described. r Soils encountered in borings EB 1 and EB4 through EB6 did not contain visual evidence or odors L+ indicating hydrocarbon contamination. As directed by Ms. Elizabeth Lu of Geomatrix, soil samples were not collected from these borings. However, soils encountered in borings EB2 and i EB3 contained visual evidence and odors indicating hydrocarbon contamination. Therefore, samples were collected from boring E132 at a depth of 11 feet bgs and from boring EB3 at depths of 9.5 and 10.5 feet bgs. Samples from similar depths were collected and submitted to Geomatrix. rSoils encountered consisted predominantly of clay and silt. A fine-grained sandy lens was present �+ in borings EB2 and EB3 from approximately 14 to 16.5 feet bgs and in boring EB4 from a depth of 5.5 feet to approximately 7 feet bgs. Borings EB2 and EB3 contained hydrocarbon-bearing soils beginning at a depth between 6.5 and 8.5 feet bgs and extending to a depth ranging from 11.5 ! to 15 feet bgs. The depth to groundwater ranged from 10.6 feet bgs in boring EB 1 to 12.2 feet bgs in borings EB3,EB4, and EB6. As directed by CPL, no groundwater samples were collected. Boring logs are included in Attachment A. I t J