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�� ,\i EDMUND G. Ij r10WN JR. <br /> ,,.1��. [,OVENNOH <br /> SEI µ. <br /> C A L I P O w N 1 A MATTHEW ROORIOUE2 <br /> Water Boards Sr'p 17 <br /> 2012 FNVIRONFN PI PPOiF 11ON <br /> Central Valley Regional Water Quality Con�01R"ONTALHEALTH <br /> PERM1T1SER\IICES <br /> 11 September 2012 <br /> Michael N. Oliphant <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> P. O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW—SITE INVESTIGATION REPORT ADDENDUM, TRACY RAIL YARD, TRACY, SAN <br /> JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted the Site Investigation Report <br /> Addendum dated 2 July 2012 for the Tidewater Associated Oil Company (TAOC) 6th Street Tracy Rail <br /> Yard (TRY) project (Site), in central Tracy. The report was prepared on behalf of Chevron by AMEC <br /> Environment & Infrastructure, Inc. (AMEC). The former TAOC and Old Valley Pipeline (OVP) pipelines <br /> were present on the Site. TAOC and OVP are Chevron predecessor companies. <br /> Following review of earlier investigations, Central Valley Regional Water Quality Control Board (Central <br /> Valley Water Board) staff requested that additional characterization be completed on two different <br /> areas of the Site to define the extent of San Joaquin Valley (SJV) crude oil affected groundwater. One <br /> area, near former boring TRY-1 on the east side of the Site and the other near boring TRY-29, was at <br /> the central western part of the Site. <br /> Four offset borings were completed north of TRY-1 (within Operable Unit 2, i.e. OU-2) and five offsets - <br /> three upgradient (north) and two southwest of TRY-29 (within OU-5) were drilled to obtain groundwater <br /> samples for analysis and fuel fingerprint evaluation. One groundwater sample from each of the two OU <br /> areas was collected from borings completed about six months later, to obtain samples for fuel <br /> fingerprint analysis to clarify the earlier anomalous laboratory results. The two samples were submitted <br /> to two different analytical laboratories for fuel fingerprint evaluation. As noted below, analysis for total <br /> petroleum hydrocarbons as diesel (TPHd) was reported as non-detect (ND) by both laboratories. The <br /> fuel fingerprint determination is provided below. <br /> AMEC's report provided the following: <br /> • Analytical results for samples from the two borings upgradient of TRY-1 (OU-2) were ND for <br /> TPHd, benzene, ethylbenzene, and toluene (BTEX) compounds and detections of polynuclear <br /> aromatic hydrocarbons (PAHs) were ND and/or did not exceed screening levels. Results for <br /> the fourth boring samples (from 4 discrete depths) reported TPHd concentrations ranging from <br /> 86 micrograms per liter (Ng/L) to 1,300 pg/L; BTEX and PAH results were ND or did not exceed <br /> screening levels. <br /> • Fuel fingerprint evaluation completed for three of the four samples tested (from the same <br /> boring), were reported as detections of TPHd since results were within the diesel range. <br /> However, based on the laboratory analysis, the chromatograms exhibited a distinctly different <br /> chromatographic pattern than that of SJV crude oil. According to the laboratory interpretation of <br /> KARL E. LONGLEV SCD, P.E., CHAIR I PAMELA C. CREEDON P.E.. BCEE,EXECUTIVE OFFICER <br /> 1665 E Street.Fresno.CA 93706 ; www.waterboards.ca.gov/cenlralvallay <br /> RECvClEO PAPEF <br />