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(RWQCB Case No. 2209),to assess the source and potential impacts of low-level VOCs in groundwater adjacent to the Forward Landfill. The letter report concluded that the sporadic detection of low-level VOCs in groundwater(and lysimeter samples) at the Forward Unit are most likely due to landfill gas from unlined unit WMU-B. Forward has continued to minimize gas related impacts to groundwater by limiting interim fill areas that promote ponding of water. Furthermore, in accordance with CCR Title 27, Section 20937, Forward continues to install additional landfill gas extraction wells, as needed. Concentration Limit Thresholds As specified in the RPCMP and RWQCB Order No. R5-2003-0049 for the Forward Landfill,the routine inorganic monitoring data obtained during the third quarter 2013 monitoring period were compared to established intrawell concentration limits(CLs) calculated for the Forward Unit. The CLs are summarized in Table 2-4 and compared to the analytical results collected during the third quarter 2013. As summarized in Table 2-4,the following CLs were exceeded during the third quarter 2013 monitoring period. • Chloride at wells MW-2A and MW-13 • Nitrate-N and sulfate at well MW-14 • Sulfate at well MW-15 • Calcium, Magnesium, and Sodium at well MW-18 • Bicarbonate alkalinity at well MW-19 • pH at well MW-23R • Sodium at well M -24 Trend analyses were performed for wells and constituents that exceeded respective CLs. Statistically significant increasing trends were identified for chloride concentrations in well MW-13,nitrate-N concentrations in well MW-14, sulfate concentrations in well MW-15, and sodium concentrations in wells MW-18 and MW-24. Trend analyses are included in Appendix D. The increasing trend for sodium at background well MW-24, suggests increasing and/or changing water quality conditions upgradient of the landfill. Similarly,the increasing trends in wells MW-13, MW-14, MW-15, and MW-18 appear to coincide with the groundwater gradient reversal in the northeast corner of the landfill since the Spring of 2011. 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 July 23, 2013 at each suction lysimeter. On July 31, 2013, 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, lysimeters were reported dry, and as a result, no soil-pore liquid samples were collected during the current monitoring period. Of note, there was no access port to inspect pan lysimeters C:\2013-0021\FA_3Q13.doc 6 Geo-Logic Associates