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MUNI~nu.('1UUNIUUkJ <br /> Water Boards NviN{INM Nl 4N Irf.11f4. <br /> Central Valley Regional Water Quality Control Board <br /> TO: Shelton R. Gray �2,�� <br /> Senior Engineering Geologist <br /> FROM: C. Dean Hubbard r _ <br /> Engineering Geologist <br /> FRESNO OFFICE <br /> DATE: 8 May 2012 <br /> SUBJECT: REVIEW— HUMAN HEALTH SCREENING EVALUATION, US CAN -WELTY <br /> ROAD PROPERTY, VERNALIS, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted a Human Health Screening <br /> Evaluation report (Report; HHSE) for the US Can -Welty Road property (Site). The Report, dated <br /> 22 March 2012, was prepared for Chevron by Science Applications International Corporation <br /> Energy, Environment & Infrastructure, LLC (SAIC). The Site is at the southwest intersection of <br /> Welty Road and California State Highway 33, south of the rural community of Vernalis. I have <br /> reviewed the Report and related project documents and my comments are provided below. <br /> The Site includes part of the highway alignment, the Union Pacific Railroad (UPRR) right-of-way <br /> (ROW), and several commercial/rural/agricultural properties on both sides of Highway 33. The <br /> ROWs associated with the historical Old Valley Pipeline (OVP) are along the south side of the <br /> highway. The historical Tidewater Associated Oil Company (TAOC) crude oil pipelines are located <br /> within the UPRR ROW. The historical TAOC/OVP pipelines were owned/operated by Chevron <br /> predecessors. Two active petroleum hydrocarbon refined product pipelines are present within the <br /> UPRR easement ROW. <br /> Based on the findings, Central Valley Regional Water Quality Control Board (Central Valley Water <br /> Board) staff concurred in a 20 April 2011 letter to Chevron, that crude oil affected soil and <br /> groundwater had been delineated. There are three areas of affected soil, approximately 400 feet <br /> by 500 feet on the south end, 100 feet by 150 feet near the center and the largest at the north end <br /> of the project has approximate dimensions of 150 by 650 feet. Crude oil affected groundwater <br /> extends downgradient, northeast, to adjacent properties. The offsite properties are being <br /> investigated separately as the Ahern Road-Vernalis project. The affected area on the south end <br /> overlaps with the Vernalis Pump Station project, with regulatory oversight of the investigations <br /> provided by Central Valley Water Board staff. <br /> Onsite soil and groundwater has been affected by total petroleum hydrocarbons as crude oil <br /> (TPHc), low concentrations of certain polynuclear aromatic hydrocarbon (PAH) compounds, and <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX). Previous fuel fingerprint evaluation <br /> determined that the petroleum hydrocarbons present are consistent with weathered San Joaquin <br /> Valley crude oil <br /> KARL E. _ONGL`_Y SCD. P.E., oHnuF'AMELH C. CREEDON P.C.. BI-EE. EXECUTIVE_omCEP <br /> 1685 F Slree! F=resnc CA 9370( ww.waieroosras c0.govlcemralvalle) <br />