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tetrachloroethane(PCE)and trichlorofluoromethane(TCFM)in the sample collected from well MW-10; 1,1-DCA, cis-l,2-dichloroethene(cis-1,2-DCE), and trichloroethene(TCE) in the sample collected from well MW-14A; and PCE in the sample collected from well MW-17. In addition, PCE was detected above the PQL in the sample collected from well MW-14A. Of note,the duplicate sample collected from well MW-10 only contained one trace concentration of DCDFM,which indicates the low levels (near the MDL)measured in this well. On behalf of Forward Inc., GLA prepared a letter report dated February 14, 2001 (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 minimizing 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. New Historical Intrawell Maximum Values During the first quarter 2007 monitoring period only the bicarbonate concentration measured in well MW-IA (740 mg/L) exceeded its historical intrawell maximum value (730 mg/L). Concentration Limit Thresholds Data obtained during the first quarter 2007 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 first quarter 2007. As summarized in this table, CLs were exceeded for wells MW-lA,MW-2A, MW-3A, MW-10, MW-13,MW-14,MW-15,MW-16, MW-17, MW-18,MW-19, and MW-21. In accordance with the RPCMP,wells with exceedances of CLs will be resampled in May during the second quarter 2007 sampling event and a second independent sample will be collected in June 2007. 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 18 lysimeters. The lysimeter locations are shown on Figure 2-1. Each accessible lysimeter was inspected and vacuums were reset to approximately—10 to—26 inches of mercury on February 6 and 7, 2007. On March 8, 2007,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 E-2, W-2, LY-A, and LY-BGI had a sufficient volume of soil-pore liquid for sample collection. However, due to the limited sample volumes,lysimeter samples were only D:\2007_0043\ForwardAustin_w07.doc 6 Geologic Associates