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4. Civic Center Square 2444 Main Street, Suite 215 Fresno, California 93721-2734 (209) 264-2535 • FAX(209)264-7431 GEOMATRIX 3 June 1996 �� Project C3499 23 Mr. Michael Infuma San Joaquin County Public Health Services Environmental Health Division P.O. Box 2009 Stockton, California 95201 Subject: Hanson Property (APN 252-040-02) 7750 Schulte Road Tracy, California Dear Mr. Infurna: Geomatrix Consultants, Inc. (Geomatrix) is performing work on behalf of Chevron Pipe Line Company (CPL) for the property owned by Mrs. Maxine Hanson located at 7750 Schulte Road in Tracy, California (Hanson property). CPL's former Wait-Mendota-Richmond pipeline was located along the northern portion of this property. _A soil assessment was performed along the former pipeline by Aqua Science Engineers, Inc. (ASE) on 5 May 1995. The results of the assessment were reported in the ASE 24 May 1995 "Project Report, Subsurface Soil Assessment, ASE Job No. 2857, Schulte and Chrisman Roads, Tracy, California." A copy of this report is enclosed. The former CPL pipeline was located along the northern portion of the Hanson property as shown on Figure 2 of the ASE report. The soil assessment consisted of excavating shallow test pits every 100 feet along the former pipeline location, evaluating the soil beneath the former pipeline for the presence of discolored soil and petroleum hydrocarbon odors, and collecting a soil sample from the base of each test pit for laboratory analysis. The pipeline has been removed but was evidenced by the remains of the tar-like coating that was used to wrap the pipe; the coating material was observed at a depth of 3 feet below ground surface (bgs). Discolored soil and petroleum hydrocarbon odor were not observed in the soil beneath the former pipeline. Soil samples collected at a depth of 4 feet bgs in each excavation were analyzed for total oil and grease (TOG) and total recoverable petroleum hydrocarbons (TRPH) using EPA Methods 5502E and 5502F, respectively. Analytical results are summarized in Table 1. Low concentrations of TOG and TRPH were detected in the samples collected from locations A, C, and H. Geomatrix proposes that no additional assessment be performed at these locations. Higher concentrations of TOG and TRPH were detected in the sample collected from location E. Geomatrix proposes that one soil boring be advanced at location E to confirm that the concentrations of TOG and TRPH are attributable to the crude oil and Bunker C oil carried in the former pipeline. The soil boring will be continuously cored using a push-core system and will be advanced to a depth of 15 feet bgs. Geomatrix Consultants, Inc. Engineers, Geologists, and Environmental Scientists