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in accordance with CCR Title 27, Section 20937, Forward continues to install additional landfill gas extraction wells, as needed. New Historical Intrawell Maximum Values During the fourth quarter 2011 monitoring event, a first-time VOC detection, for DIPE, was measured in the sample collected from well MW-16. All of the other monitoring parameters were within their historical range of values. Concentration Limit Thresholds Data obtained during the fourth 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 CLs that were exceeded in samples collected from groundwater monitoring wells during the fourth quarter 2011. As summarized in this table, CLs were exceeded for DIPE at well MW-16, for chloride at upgradient(background) well MW-22, and for sulfate at wells MW-10, -15, and-22. CL exceedances for non-impact constituents (arsenic, bicarbonate, hexavalent chromium, nitrate as nitrogen, and sulfate) are not retested, and therefore, retesting for sulfate 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, only the CL exceedance for chloride at well MW-22 will require retesting. 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 November 2, 2011. On November 4, 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 Q and summarized on Table 2-5, lysimeters were reported dry to moist, 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 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 7.67 to 12.08 feet during the fourth quarter 2011 monitoring period. Appendix A presents copies of the leachate logs and the freeboard observation logs. c:\zooi-0050Tn_4QILdoc 6 Geo-Logic Associates