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summarizes CLs that were exceeded in samples collected from groundwater monitoring wells during the fourth quarter 2010. As summarized in this table, CLs were exceeded for hexavalent chromium at well MW-2A; potassium and sulfate at well MW-18; chloride,nitrate as nitrogen, and sulfate at well MW-22; and sulfate at wells MW-10, 13, 15, and 17. CL exceedances for non-impact constituents (arsenic,bicarbonate, hexavalent chromium,nitrate as nitrogen, and sulfate) are not retested, and therefore, retesting for these five constituents is not required. In addition, CL exceedances for low- level VOCs are not retested since similar low-level VOCs have been confirmed at the Forward Unit. Therefore, in accordance with the RPCMP, wells with CL exceedances of impact constituents (as defined in Table 5-3 of the RPCMP), include potassium at well MW-18, and chloride at well MW-22, will be resampled in February during the first quarter 2011 sampling event and a second independent sample will be collected in March 2011. The results of the retesting events will be submitted to DTSC and RWQCB under separate cover. 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 Dec 15, 2010. On December 27, 2010, 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 fourth quarter 2010, leachate was observed at all of the holding areas except MrMU D-87 and WMU D-88 A/B. Freeboard at WMU-F ranged from approximately 11.25 to 12.08 feet during the fourth quarter 2010 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. In addition, to monthly monitoring, leachate is sampled annually during the fourth quarter monitoring period for the parameters listed in Table 2-1. Results of monthly field monitoring measurements, and analytical results for the fourth quarter 2010 are presented in Table 2-6. As shown on Table 2-6, 13 dissolved metal constituents were measured with eight above their PQL; three VOCs were measured above their PQL; eight semi-volatile organic compounds (SVOCs) were measured with three above their PQL; and one herbicide was measured above its PQL in the leachate sample collected during the fourth quarter 2010 monitoring period. No pesticides were detected in the leachate sample. The results of the annual leachate D:\2010_0013\FA_4Q10.doc 7 GeoLogic Associates