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California Regional Water Quality Control Board <br /> Central Valley Region Go <br /> ' Robert Schneider Chair <br /> Alan C.Lloyd,Ph.D. ' Arnold <br /> Secretaryfor Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 Governor <br /> Protection (559)445-5116•Fax(559)445-5910 MOWED <br /> http://www.waterboards.ca.gov/centralvalley I��-L{l v <br /> 8 March 2005 MAR 1 0 2005 <br /> M. Scott Mansholt ENVIROWENT HEALTH <br /> ChevronTexaco PERMIT/SERVICES <br /> Chevron Environmental Management Company <br /> P.O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW OF SOIL AND GROUNDWATER INVESTIGATION, POMBO PROPERTY, TRACY, <br /> SAN JOAQUIN COUNTY <br /> ChevronTexaco has conducted soil and groundwater investigations at the Pombo property, 1755 West 11th <br /> Street, in Tracy, San Joaquin County from 1999 to 2004. The purpose was to determine the lateral and <br /> vertical extent of soil and groundwater impacts caused by petroleum hydrocarbon leaks from an <br /> abandoned crude oil pipeline (Old Valley Pipeline, OVP) in operation from the early 1900s to the late <br /> 1950s. <br /> Currently, a City of Tracy Fire Department building, offices and parking lot covers the site. A retail <br /> shopping mall is adjacent to the west and another is to the south, across West 11"' Street. The former OVP <br /> easement, the Union pacific Railroad, and the West Side Irrigation easement are adjacent to the north. <br /> Adjacent to these easements further north is residential housing. <br /> The earlier investigation was conducted by Earth Systems Consultants (ESC)with subsequent reports <br /> completed by Geomatrix Consultants (Geomatrix), and the most recent by Science Applications <br /> International Corporation(SAIC). Subsequent to the earlier investigations, a human health risk screening <br /> evaluation(HHSE) was prepared by Geomatrix for ChevronTexaco (January 2000) and submitted to the <br /> Department of Toxic Substances Control (DTSC) for review. Following the DTSC review and follow-up <br /> comments by Geomatrix,the DTSC concurred with the HHSE findings. The DTSC response, dated 27 <br /> April 2000 stated that the total risk falls within the acceptable range, and the petroleum constituents in soil <br /> do not pose an"unacceptable risk". <br /> Following the DTSC response and comments, additional site characterization and delineation work was <br /> conducted and an updated HHSE was prepared by Geomatrix (December 2000). The additional field <br /> investigations were evaluated(by ChevronTexaco and Geomatrix) for updating potential human health <br /> risks associated with residual petroleum hydrocarbons in soil and groundwater identified by the later work. <br /> The updated HHSE, dated 4 October 2001, was submitted to the DTSC for further review and comment. <br /> The DTSC in their 5 August 2002 memorandum to ChevronTexaco again concurred that the site <br /> development is acceptable and the risk falls within the acceptable range of 1 X 10-4 to 1 X 10-6. Further, <br /> the current land use (commercial/industrial) is acceptable provided a land use covenant(i. e., deed <br /> restriction) is applied to the site limiting future development of the site for residential use. <br /> California Environmental Protection Agency <br /> �c3 Recycled Paper <br />