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California gional Water Quality Con4l Board t Central Valley Region �. Linda S.Adams �( Arnold Secretary for ^{I ��I I I`V� L chwarzenegger Environmental Governor Protection Fresno Branch Office 1685 E Street,Fresno,California 93706 (559)445-5116•Fax(559)445-5910 DEC 1 6 2006 http://www.waterboards,ca.gov/centralvalley ENVlRON101ENT HEALTH Fn UU"T;�.�RVICES TO: Shelton R. Gray FROM: C. Dean I�u rd files Engin ring Geologist DATE: 13 December 2006 SIGNATURE: SUBJECT: REVIEW OF SITE INVESTIGATION, TAOC TRACY GRAVEL PITS, TRACY, SAN JOAQUIN COUNTY have reviewed the Soil and Groundwater Investigation report for the Tidewater Associated Oil Company (TAOC) Tracy Gravel Pits property located in southeast Tracy. The report, dated 3 October 2006 was prepared for Chevron and Union Pacific Railroad (UPRR) by their consultant, Geomatrix. The TAOC Tracy Gravel Pits property, located on Valpico Road, one- quarter mile west of MacArthur Drive, is jointly owned by Chevron and UPRR, and comprises approximately 34 acres. The site is divided diagonally into three sections: northeast and southwest sections that are separated by a former gravel pit excavation (approximately 15 to 20-feet deep) that extends from the northwest to the southeast corners of the site. There are no structures or improvements other than a perimeter fence. Background Gravel was excavated from the site in the early 1900's to provide baserock for the UPRR railroad; a short spur extending diagonally on to the site from the northwest corner was previously used to transport gravel from the site. The spur was removed sometime between 1940 and 1954. The former OVP and/or TAOC pipeline systems were not located on this site. Historic maps depict a wooden pipeline extending to an oil sump located in the northern part of the site. Reportedly, the wooden pipeline was installed in 1910 between the TAOC Tracy Pump Station (located approximately one and one-half miles to the northwest) and the gravel pits excavation. Apparently, prior to the 1950's the tank bottoms was allowed to separate in the gravel pits and the accumulated surface oil was burned; this practice was later discontinued. The buried pipelines (present within the UPRR right-of-way) connected to the TAOC Tracy Pump Station, were removed sometime between 1968 and 1973. According to a 1989 Kleinfelder Soil Assessment Report, in the 1950s the site may have been used for waste disposal by others including the City of Tracy and by the Laura Scudders' potato chip plant in the 1960s. Reportedly, local farmers may have drained irrigation water into the gravel pit. The property has remained vacant since the mid-1970s and no known or observed material has been discarded at the site. California Environmental Protection Agency cpi Recycled Paper