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ARCADIS 2010/2011 Annual <br /> Monitoring Report <br /> Union Pacific Railroad <br /> Company <br /> Tracy, CA- Maintenance <br /> 5.3.2 B-Zone Facility <br /> TEPH-d was detected in one(MW-12B; 220 pg/1)of the nine B-zone wells sampled <br /> during the March 2011 annual monitoring event above the 100 pg/l CAO cleanup level. <br /> TEPH-d hasn't been detected in a sample collected from well MW-12B since March <br /> 2008 (340 pg/1). This is likely a result of seasonal advection and dispersion of dissolved <br /> TEPH-d. This well will continue to be evaluated for seasonal fluctuations. <br /> 5.3.3 C-Zone <br /> TEPH-d was detected in one (MW-01C; 230 pg/1)of the two C-zone wells sampled <br /> during the March 2011 annual monitoring event above the 100 pg/l CAO cleanup level. <br /> TEPH-d hasn't been detected in a sample collected from well MW-01C since March <br /> 2008 (99 pg/1). This is likely a result of seasonal advection and dispersion of dissolved <br /> TEPH-d. This well will continue to be evaluated for seasonal fluctuations. <br /> 5.4 Volatile Organic Compounds Analytical Results <br /> VOC analytical results for historic groundwater samples collected between February <br /> 2000 and March 2010 are summarized in Table 4. VOCs were not analyzed during the <br /> 2010/2011 reporting period. <br /> 5.5 Biogeochemical Analytical Results <br /> Biogeochemical analytical results since March 2010 are summarized in Table 5. This <br /> data was collected to further evaluate groundwater quality. The following maximum <br /> biogeochemical concentrations ranges were detected in the A-zone monitoring wells <br /> during the 2010/2011 reporting period: <br /> • total iron (0.46 milligrams per liter[mg/1]), sulfate(270 mg/1), chloride (250 mg/1), <br /> and oxygen (4.4 mg/1) in well MW-26A <br /> • total manganese (0.068 mg/1), DOC (7.4 mg/1), TOC (7.9 mg/1), alkalinity(440 <br /> mg/1), ethene(0.023 pg/1), and methane (14 pg/1) in well TW-03 <br /> • ethane(0.006 pg/1)and nitrogen (20 mg/1) in well MW-14A <br /> • nitrate(13 mg/1) in wells MW-22A and MW-26A <br /> • carbon dioxide (38 mg/1) in wells MW-14A, MW-22A, TW-03 <br /> final_ta y,.-maint fadlity_AnnRpt_4-26-2011.d- Page:5/7 <br />