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California Regional Water Quality Control Board <br /> Central Valley Region <br /> Katherine Hart, Chair <br /> 1685 E Street,Fresno,California 93706 Edmund G.Brown Jr. <br /> Matthew Rodriquez (559)445-5116•FAX(559)445-5910 Governor <br /> Secrelagjbr http://www.waterboards.ca.gov/centralvalley <br /> Environmental Protection <br /> �� FROM: C. Dean Hubbard <br /> To: Shelton R. Gray <br /> Senior Engineering Geologist Engineing Geologist <br /> DATE: 10 August 2011 SIGNATURE: <br /> SUBJECT: REVIEW— HUMAN HEALTH SCREENING EVALUATION, TRACY BYRON <br /> ROAD PROJECT, TRACY, SAN JOAQUIN COUNTY, CA <br /> I have reviewed the 25 May 2011 Human Health Screening Evaluation (HHSE) Report, Tracy <br /> Byron Road Project, Tracy, San Joaquin County. The report was prepared for Chevron <br /> Environmental Management Company (Chevron) by Science Applications International <br /> Corporation — Benham Companies, LLC (SAIC). In conjunction, I reviewed 2003 to 2010 <br /> project related investigation reports prepared for Chevron by SAIC. <br /> During the 2003 installation of a City of Tracy stormwater drain system beneath West Byron <br /> Road, approximately 7,000 feet in length, crude oil affected soil and groundwater was <br /> encountered at a number of locations. The investigations determined the origin was likely <br /> from the nearby historical Old Valley Pipeline (OVP) and/or the Tidewater Associated Oil <br /> Company (TAOC) pipelines. The historical pipelines were utilized by Chevron predecessors <br /> from the early 1900's until the 1970's to transport crude oil from Kern County oil fields to San <br /> Francisco Bay area refineries. The historical pipelines, located along the south side of the Site, <br /> are within a right-of-way which also contains Union Pacific Railroad (UPRR) tracks and active <br /> refined petroleum product pipelines. <br /> The OVP lies along the south side of the Byron Road right-of-way (ROW) easement. The <br /> TAOC lines, north of West Byron Road and the Union Pacific Railroad (UPRR) tracks are <br /> located between West Byron Road and the TAOC lines. Overall, the combined width of the <br /> UPRR, Byron Road, and pipelines' ROW easements, varies between 200 and 240 feet. <br /> However, the offsite areas of investigation extended beyond the easements. <br /> According to historical project documents, soil and groundwater investigations were conducted <br /> on adjacent downgradient properties to the north. With the exception of the Surland Homes <br /> project, between 1996 and 2002, No Further Action (NFA) determinations for several of the <br /> properties were approved by the San Joaquin County Environmental Health Department <br /> (SJCEHD) or the Sacramento office of the Central Valley Regional Water Quality Control <br /> Board (Central Valley Water Board). The Surland Homes site is currently being addressed by <br /> Chevron. Additionally, part of the crude oil affected upgradient sites to the south, were issued <br /> NFA closures by the SJCEHD in the late 1990's. <br /> The previous investigations identified 12 crude oil affected areas that were evaluated and the <br /> extent of crude oil impacts was defined. For the purpose of the HHSE, the various areas were <br /> combined and evaluated as Area 1, 2, and 3, at the northwest, central, and southeast portions <br /> California Environmental Protection Agency <br /> ca Recycled Paper <br />