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0 Concentration Limit Thresholds Data obtained during the third quarter 2011 monitoring period were compared to concentration limits (CLs) as specified in the RPCMP for the Forward Landfill. CLs were calculated by Herst & Associates and are included in Appendix D. Table 2-4 summarizes the CLs that were exceeded in samples collected from groundwater monitoring wells during the third quarter 2011. As summarized in this table, CLs were exceeded for DIPE in well MW -2A; PCE and WE in well MW -14; barium and sulfate in wells MW -15; potassium and sodium in well MW -18; chloride in well MW -21; and for potassium and sulfate in well MW -22. In accordance with the RPCMP, only wells with CL exceedances of impact constituents (as defined in Table 5-3 of the RPCMP) need to be resampled, and therefore, retesting for sulfate is not required. Furthermore, a No Release Demonstration (NRD) (Herst, 2011) was performed for CL exceedances of potassium in well MW -18. The results of the NRD indicate that the CL exceedances for potassium are not the result of a release from the facility, and therefore, retesting of potassium will not be performed. In addition, CL exceedances for low-level VOCs are not retested since similar low-level VOCs have been confirmed at the Forward Unit. Therefore, CL exceedances require retesting will be conducted for barium at well MW -15 and sodium at well MW -18. 2.1.5 Vadose Zone Monitoring The current vadose-zone monitoring network at the Forward Unit consists of 17 lysimeters. The lysimeter locations are shown on Figure 2-1. Each accessible lysimeter was inspected and vacuums were reset to approximately —25 inches of mercury on August 16, 2011. On August 20, 2011, the lysimeters were again checked and positive pressure was applied to evacuate the accumulated sample. As recorded in the field notes for lysimeters (Appendix C) and summarized on Table 2-5, all lysimeters were reported dry, and as a result, no soil -pore liquid samples were collected during the current monitoring period. 2.1.6 Leachate Monitoring Leachate sumps are inspected for the presence of leachate and observations are recorded at least weekly by Forward Landfill personnel. If leachate is detected in a sump, it is pumped into the surface impoundment (WMU F) for evaporation. During the third quarter 2011, leachate was observed at all of the holding areas except WMU D-87 and WMU D-88 A/B. Freeboard at WMU-F ranged from approximately 5.17 to 10.25 feet during the third quarter 2011 monitoring period. Appendix A presents copies of the leachate logs and the freeboard observation logs. Leachate samples were collected on a monthly basis and analyzed in the field for pH, specific conductance, and temperature. Results of monthly field monitoring measurements for the third quarter 2011 are presented in Table 2-6. c:\2011-0050\FA_3Qu.aoa 6 Geo -Logic Associates