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GAMIN NEWSOM <br /> C'CIVFRNOR <br /> ARCIA <br /> Water <br /> 'RETAARVF R <br /> /�� <br /> I ater Boards ENVIRONMENTAL PROTECTION <br /> Central Valley Regional Water Quality Control Board <br /> 29 November 2023 <br /> Mike Makerov Union Pacific Railroad Company <br /> Union Pacific Railroad Company 1408 Middle Harbor Road <br /> 2015 South Willow Avenue Oakland, CA 94607 <br /> Bloomington, CA 92316 <br /> CONDITIONAL CONCURRENCE WITH SITE INVESTIGATION WORK PLAN, <br /> UNION PACIFIC FORMER BUNKER C VAULT: TRACY(T10000021214), <br /> 780 EAST 6rH STREET, TRACY, SAN JOAQUIN COUNTY <br /> Central Valley Regional Water Quality Control Board staff has reviewed the 30 October <br /> 2023 Additional Site Investigation Work Plan (Work Plan) for the Union Pacific Railroad <br /> Company (Union Pacific) property located at 780 East 6th Street in Tracy (Site). On <br /> behalf of Union Pacific, Antea Group submitted the Work Plan for the investigation of <br /> subsurface impacts from potential releases from the abandoned underground fuel tank <br /> infrastructure that exists at the Site. <br /> In the Work Plan, Antea Group proposed advancing multiple borings to assess <br /> subsurface conditions near the location of the abandoned underground sump on Site. <br /> For the investigation near this structure, Antea Group stated that it will advance vertical <br /> borings five feet outside of each end of the sump. Antea Group also proposed angled <br /> borings beneath the north and south sides of the sump. Antea Group stated that it will <br /> advance the vertical borings to a depth of at least 10 feet below ground surface (bgs) <br /> but did not specify a terminal depth for the angled borings. Antea Group stated that soil <br /> samples will be collected from each boring at intervals of two to three feet in depth and <br /> that the soil samples from a depth of two feet below the base of the sump will be <br /> analyzed. <br /> If groundwater is encountered at the proposed boring depths, Antea Group stated that it <br /> will collect a grab groundwater sample. If groundwater is not encountered at the initial <br /> boring depths, Antea Group will continue to advance the borings to either a sufficient <br /> depth to collect a grab groundwater sample or to the depth where the soil impacts are <br /> vertically delineated above the water table. Additionally, if liquid or sediment are present <br /> inside the sump during the investigation, Antea Group planned to collect liquid and <br /> composite soil samples from within this structure to characterize the waste for off-Site <br /> disposal. <br /> Antea Group specified that it will analyze all samples for diesel and oil range organics <br /> using EPA Method 8015B, methyl tertiary butyl ether (MTBE), naphthalene, benzene, <br /> toluene, ethylbenzene, and xylenes (BTEX) using EPA Method 8260B, polycyclic <br /> MARK BRADFORD, CHAIR I PATRICK PULUPA, Eso., EXECUTIVE OFFICER <br /> 11020 Sun Center Drive##200, Rancho Cordova, CA 95670 1 www.waterboards.ca.gov/centralvalley <br />