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California R Tonal Water Quality Con' I Board <br /> Central Valley Region ` <br /> Katherine Hart, Chair <br /> Linda S.Adams Arnold <br /> Secretary for 1685E Street, Fresno,California 06 Schwarzenegger <br /> Environmental (559)445-5116 • Fax(559)445-5915910 Governor <br /> Protection http://www.waterboards.ca.gov/centraIvaIley <br /> To: Shelton R. Gray FROM: C. Dean Hubbard <br /> Senior Engineering Geologist Engineering ologist <br /> DATE: 2 December 2010 SIGNATURE: <br /> SUBJECT: REVIEW— HUMAN HEALTH SCREENING EVALUATION, FORMER <br /> VERNALIS PUMP STATION, VERNALIS, SAN JOAQUIN AND STAN/SLAUS <br /> COUNTIES, CA <br /> Chevron Environmental Management Company (Chevron) submitted a Human Health <br /> Screening Evaluation report (Screening Evaluation) for the former Vernalis Pump Station (Site) <br /> in Vernalis. The Report, dated 2 September 2010, was prepared for Chevron by Science <br /> Applications International Corporation — Benham, LLC (SAIC). The Site is one-half mile south <br /> of Grant Road, southeast of the intersection of Welty Road and California State Highway 33. <br /> The Union Pacific Railroad (UPRR) right-of-way easement is on the east side of the Site, <br /> adjacent to Highway 33. The historical Old Valley Pipeline (OVP) and the Tidewater <br /> Associated Oil Company (TAOC) crude oil pipelines are present between the east side of the <br /> Site and the UPRR railroad tracks. The historical OVP/TAOC pipelines conveyed heated <br /> crude oil from Kern County to Richmond area refineries from the early 1900s until deactivation <br /> in the late 1960s to early 1970s. Associated crude oil pump stations were used for heating the <br /> crude oil to facilitate movement through the pipelines. A petroleum product pipeline that <br /> transmits gasoline, jet fuel, and diesel is located within the UPRR right-of-way easement <br /> adjacent the east side of the Site. <br /> I have reviewed the September 2010 Screening Evaluation and soil and groundwater <br /> investigation reports prepared between 2002 and 2008 for Chevron by SAIC and other <br /> consultants. Earlier investigations, also by other consultants, beginning in approximately <br /> 1995, are summarized in the more recent reports. My review comments are provided below. <br /> Previously, Central Valley Regional Water Quality Control Board (Central Valley Water Board) <br /> staff concurred in a November 2008 letter to Chevron that based on the earlier findings, crude <br /> oil affected soil and groundwater had been delineated, adequate monitoring data had been <br /> collected and a health screening evaluation could be prepared. <br /> Onsite soil and groundwater has been affected by total petroleum hydrocarbons as crude oil <br /> (TPHc), low levels of certain polynuclear aromatic hydrocarbon (PAH) compounds, and <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX). In addition, affected soil extended <br /> slightly offsite to the east and was adequately delineated beneath Highway 33 and slightly <br /> beyond, to adjacent agricultural property. The offsite downgradient extent of affected <br /> groundwater is larger than the area of affected soil further to the east, beneath the same <br /> California Environmental Protection Agency <br /> ZYecycled Paper <br />