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Californ7 Iegional Water Quality C( rol Board E..•o' <br /> !� Central Valley Region <br /> Katherine Hart, Chair <br /> 11020 Sun Center Drive,#200,Rancho Cordova,California 95670-6114 <br /> Matthew Rodriquez (916)464-3291 •FAX(916)464-4645 Edmund G.Brown Jr. <br /> Secretaryfor http://www.waterboards.ca.gov/centralvalleyGovernor <br /> �� <br /> Environmental Protection I VE jam, <br /> 23 September 2011 <br /> SEP 272011 <br /> ENVIRONA4EN-4L H <br /> �'ERIli11T/SERVIC SLT►� <br /> Mr. James Diel <br /> Union Pacific Railroad <br /> 9451 Atkinson Street, Suite 100 <br /> Roseville, CA 95747 <br /> 2010/2011 ANNUAL MONITORING REPORT AND MONITORING WELL NETWORK <br /> REDUCTION RECOMMENDATION LETTER, UNION PACIFIC RAILROAD, MAINTENANCE <br /> FACILITY, TRACY, CALIFORNIA <br /> The California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff has reviewed Arcadis' Response to Comments, 2010/2011 Annual <br /> Monitoring Report (Report) dated 26 April 2011 and the Monitoring Well Network Reduction <br /> Recommendation Letter(Letter) also dated 26 April 2011 for the Union Pacific Railroad <br /> (UPRR) Maintenance Facility (Site) in Tracy. Arcadis prepared the Report and Letter on <br /> behalf of UPRR. The Report provides a summary of groundwater monitoring and sampling <br /> activities conducted at the Site between 1 April 2010 and 31 March 2011. The Report also <br /> discusses the total extractable petroleum hydrocarbons as diesel (TEPH-d) impacts and the <br /> light non-aqueous phase liquid (LNAPL) plume at the Site. The Letter provides <br /> recommendations for abandonment of monitoring wells that are believed to be no longer <br /> needed by UPRR. Below staff has provided comments on the Report and Letter regarding the <br /> Site. <br /> Annual Report <br /> 1. In the Summary and Planned Activities Section 7.0 of the Report, Arcadis states: <br /> "Dissolved—phase TEPH-d in the A-Zone is laterally well defined, remains stable and local <br /> to the source area." Staff does not concur with this statement based on review of Figure 9 <br /> (A-Zone TEPH Concentration Contours Between 2006 and 2011). The data on Figure 9 <br /> indicates a northeastern to eastern migration of dissolved TEPH. In general, the figure <br /> shows an increasing TEPH trend in well MW-22A from <50 micrograms per liter (ug/L) in <br /> March 2006 to 300 ug/L in March 2009. The TEPH concentration in this well remained at/or <br /> above 200 ug/L for the March sampling events of 2010 and 2011. On the same figure, well <br /> MW-24A, installed in 2010, showed a TEPH concentration increase from <54 ug/L in <br /> March 2010 to 180 ug/L in March 2011. In addition, well MW-25A, which has had fairly <br /> consistent TEPH concentrations in the 200-300 ug/L range, showed a jump of 80% from <br /> the previous sampling event from 310 ug/L to 560 ug/L. The increases in these wells <br /> indicate that the TEPH plume is not stable and that an additional well is warranted east- <br /> northeast of MW-24A. Please prepare a work plane to address this concern and submit it <br /> to staff by 28 October 2011. <br /> 2. The TEPH plume also appears to be undefined southeast of MW-25A, MW-22A and MW- <br /> 24A. Based on the TEPH contours on Figure 9, the TEPH plume appears to be migrating <br /> California Environmental Protection Agency <br /> ca Recycled Paper <br />