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"-F EUMUNU G. Bnuv+N Jn. GOVERNOR C A l I f O P M I A MATTHEw CRETARY ROOORIOUEZ WaterBoards EN-ONMENIA,PROTECTIOI, Central Valley Regional Water Quality Control Board TO: Dane Johnson' q Senior Engineering 6eologist P.G. No. 4239 FROM: C. Dean Hubbard Engineering Geologis P.G. No. 6357 DATE: 7 February 2014 SUBJECT: HUMAN HEALTH AND ECOLOGICAL SCREENING EVALUATION, TAOC 6T" STREET TRACY RAIL YARD PROPERTY, TRACY, SAN JOAQUIN COUNTY Chevron Environmental Management Company (Chevron) submitted the subject report dated 30 September 2013. The report summarizes the findings of the Human Health and Ecological Screening Evaluation (HHESE). The subject property (Site) was used as a railroad maintenance facility until the 1940s. Those operations had ceased and the majority of the Site features were removed by the 1980s. Currently, the Site is owned by the Union Pacific Railroad (UPRR), except for two parcels recently sold to the City of Tracy for construction of the Tracy Transit Station. Future use for the remainder of the Site is not known but may be considered for commercial and/or residential development. The investigative findings conducted on the two remaining parcels (operable unit 2 and operable unit 5 [OU-2 and OU-5 respectively] are a combined 56 acres in size) are the subject of and contributed to compilation of the HHESE. The other two parcels of this project, OU-3 and OU-4, were previously investigated for UPRR with regulatory oversight provided by California Department of Toxic Substances Control (DTSC) staff; these two parcels will be developed as the City of Tracy Transit Station. Background The Site is located at 6th Street and Central Avenue in central Tracy and includes a portion of the former right-of-way for the historical Tidewater Associated Oil Company (TAOC) pipeline system which crosses the property east to west. A short section of the former Old Valley Pipeline (OVP), located along the east side of the Site, enters the property at the southeast corner; the terminus of the OVP is located at the east-central side of the property. The OVP and TAOC pipelines, constructed in the early 1900s, transported crude oil from Kern County oil fields to Bay Area refineries. Portions of the OVP were used in the 1940s to convey Bunker C locomotive fuel from the refineries to railroad hubs in Tracy. The TAOC lines were decommissioned about 1968 and the OVP pipelines were removed from service by the early 1970s. The previous subsurface investigations have delineated the lateral limits of petroleum hydrocarbons in soil and groundwater. Prior soil and groundwater investigations completed since about 2004 were on behalf of the UPRR, City of Tracy, and a prospective buyer of the Site. The DTSC provides regulatory oversight for investigations associated with historical UPRR activities documented at the Site. To evaluate the presence of crude oil leaks associated with the historical OVP and TAOC crude oil pipelines, Chevron conducted Site investigations from about 2005 to 2012. Concurrent with the UPRR Site investigations, investigations associated with Chevron's historical OVP and TAOC KARL E. LONOLEV SCD, P.E.. CHAIR I PAMELA C. CREEDON P.E.. BCEE, EXECUTIVE orrlcEr, 1685 E Street,Fresno,CA 93706 1 www.waterboards.ca.gov/centralvalley `�RECYCLED I-ER