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j California R ional Water Quality Cont-1 Board ,�.. , <br /> Central Valley Region +' ; <br /> Katherine Hart, Chair <br /> Linda S.Adams 1685 E Street, Fresno, California 93706 Arnold <br /> Secretary for (559)445-5116 • Fax(559)445-5910 Schwarzenegger <br /> Environmental http://www.waterboards.ca.gov/centralvalley Governor <br /> Protection RECEIVED <br /> 2 December 2010 <br /> DEC 0 6 2010 <br /> ENVIRONMENTAL HEALTH <br /> Lee Higgins PERMIT/SERVICES <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> BR1 Y/3484 <br /> San Ramon, CA 94583 <br /> REVIEW — HUMAN HEALTH SCREENING EVALUATION, FORMER VERNALIS PUMP <br /> STATION, VERNALIS, SAN JOAQUIN AND STANISLAUS COUNTIES, CA <br /> Chevron Environmental Management Company (Chevron) submitted the 2 September 2010 <br /> report entitled Human Health Screening Evaluation (Screening Evaluation), Former Vernalis <br /> Pump Station (Site), at 35500 Welty Road, Vernalis, San Joaquin and Stanislaus Counties. <br /> Science Applications International Corporation — Benham, LLC (SAIC) prepared the report for <br /> Chevron. <br /> The Site is one-half mile south of Grant Road, southeast of the intersection of Welty Road and <br /> California State Highway 33. The Union Pacific Railroad (UPRR) right-of-way easement is on <br /> the east side of the Site, adjacent to Highway 33. The historical Old Valley Pipelines (OVP) <br /> and the Tidewater Associated Oil Company (TAOC) crude oil pipelines are located between <br /> the east side of the Site and the UPRR railroad tracks. <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has <br /> reviewed the September 2010 Screening Evaluation and related 2002 — 2008 soil and <br /> groundwater investigation reports prepared for Chevron by SAIC and other consultants. <br /> Earlier investigations, also by other consultants beginning in approximately 1995, are <br /> summarized in the more recent reports. Detailed comments, provided in the enclosed <br /> memorandum, are summarized below. <br /> Based on the findings, Central Valley Water Board staff concurred in a November 2008 letter <br /> to Chevron, that crude oil affected soil and groundwater had been delineated, adequate <br /> monitoring data had been collected and a health screening evaluation could be prepared. <br /> SAIC's report determined that the potential onsite residential cancer risk was 1 E-06, <br /> equivalent to the de minimus level of 1 E-06 (i.e., one in one million). The total potential non- <br /> cancer hazard from oral, dermal, and inhalation exposure to onsite soils of 3E-03 is well below <br /> the de minimus level of 1 which is also a conservative estimate of risk. Results of the <br /> Screening Evaluation indicate that exposure to petroleum hydrocarbons in soil at the Site, <br /> should not result in unacceptable health risks for an adult or child resident. <br /> California Environmental Protection Agency <br /> CaRecycled Paper <br />