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Concentration Limit Thresholds Data obtained during the first quarter 2008 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 2008. As summarized in this table, CLs were exceeded for wells MW-lA, MW-2A, MW-3, MW-10, -13,MW-14,MW-15, MW-16, MW-17, MW-18, and MW-19. In accordance with the RPCMP, wells with CL exceedances (other than arsenic, bicarbonate, hexavalent chromium, nitrate as nitrogen, and sulfate, which the RPCMP do not consider impact constituents)will be resampled in May during the second quarter 2008 sampling event and a second independent sample will be collected in June 2008. 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—5 to—25 inches of mercury on February 6 and 7, 2008. On March 18, 2008,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-BG1 had a sufficient volume of soil-pore liquid for sample collection. However,due to the limited sample volumes,lysimeter samples were only analyzed for select general chemistry constituents and/or VOCs. As shown in Table 2-6, a total of two VOCs (both above the PQL), were measured in the lysimeter samples collected during the first quarter 2008 monitoring period. However, the concentration of t-butyl alcohol is a suspected field/laboratory contaminant since a similar concentration was also measured in the QA/QC field blank. 2.1.6 Surface Water Monitoring Site run-on and run-off control facilities are designed to effectively channel surface water to site stormwater/sedimentation ponds. According to the Operations Manager,no surface water was discharged from the facility during the reporting quarter. During the first quarter 2008 monitoring period, surface-water monitoring stations FSW-1 and FSW-2 were sampled on February 4, 2008. Table 2-8 summarizes the current analytical results for surface water samples collected at the Forward Unit. No VOCs were detected in the samples collected from the surface water stations during the first quarter 2008 monitoring period. A comparison of upgradient(FSW-2)to downgradient(FSW-1) surface water samples indicates generally similar concentrations suggesting that the landfill operations are not impacting surface water quality. D:U007 0043XFA_IQ08.doc 6 Geologic Associates