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California Rr-ional Water Quality Antrol Board <br /> E <br /> Central Valley Region ,, i) <br /> Karl E. Longley.ScD, P.E.,Chair <br /> Linda S. Adams Arnold <br /> s- <br /> crelarT_lor Sacramento Main Office Schwarzenegger <br /> linrunmenral <br /> 11020 Sun Center Drive#200.Rancho Cordova.California 95670-6114 Governor <br /> l'rolecrlon (916)464-3291 <br /> htip://N%NYNN.�%,aterboards.ca.gov/centraix,alleN, <br /> 22 April 2008 G�ECME iEDD <br /> Mr. James Diel APR 2 4 2008 <br /> Manager, Site Remediation ENVIRONNIEN1'HEALTH <br /> Union Pacific Railroad Company PERMIT/SERVICES <br /> 9451 Atkinson Street, Suite 100 <br /> Roseville, CA 95747-5528 <br /> LIQUID PHASE HYDROCARBON INVESTIGATION WORK PLAN, UNION PACIFIC <br /> RAILROAD COMPANY, FORMER MAINTENANCE FACILITY, 720 EAST 6TH STREET, <br /> TRACY, SAN JOAQUIN COUNTY <br /> The California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff has received and reviewed the 29 February 2008 Liquid Phase Hydrocarbon <br /> Investigation Work Plan (Workplan) for Union Pacific Railroad's (UPRR) former maintenance <br /> facility in Tracy. The Workplan was prepared by Arcadis U.S., Inc. (Arcadis) on behalf of <br /> UPRR and proposes to use cone penetrometer testing (CPT) borings with a laser induced <br /> fluorescence system (LIFS) to delineate nonaqueous liquid phase hydrocarbons (NAPL) in the <br /> subsurface. The data collected from the proposed NAPL delineation Workplan will be used to <br /> assess the source area extent of the remaining NAPL and evaluate the technical practicability <br /> of removing residual NAPL from this area. <br /> Based on our review of the Workplan, the Regional Water Board staff conditionally concurs <br /> with the proposed use of CPT borings with a LIFS to delineate the extent of the NAPL source <br /> area. As a condition of our concurrence, the following comments must be addressed and <br /> implemented: <br /> 1 . Given that the site groundwater levels have changed over the years either by <br /> seasonal groundwater fluctuations or by the operation of the multiphase extraction <br /> (MPE) system, the CPT borings should be advanced to the lowest recorded water <br /> levels, including those levels achieved by the operation of the MPE system. <br /> Additionally, to determine depth of the NAPL smear zone, only the actual physical <br /> groundwater measurements (non-adjusted) should be used where NAPL is present. <br /> The true depth of the NAPL smear zone would be just below the actual measured <br /> depth of water beneath the NAPL. Therefore, in this phase of the investigation the <br /> borings should be advanced below the lowest physically measured depth of NAPL <br /> until the LIFS indicates that there is no NAPL present for at least 3 feet. <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />