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6 CORRECTIVE ACTION MONITORING PROGRAM <br /> Groundwater and surface water quality at the Corral Hollow Sanitary Landfill are <br /> currently monitored consistent with two monitoring programs: WDR Order No. 94-259 <br /> Monitoring and Reporting Program and the EMP (EMCON, 1993). These two programs <br /> are described below. <br /> Groundwater quality at the site has been monitored since 1988. The site's monitoring well <br /> network consists of six wells (MW-1 through MW-5, and SB-1; see Figure 2). The deep <br /> water-bearing zone, which historically flowed to the southeast, is monitored by wells <br /> MW-1, MW-2, and MW-3. MW-2 is the background well for this water-bearing zone. <br /> However, these wells have been dry since 1991. <br /> The shallow water-bearing zone is a perched groundwater zone that is monitored by wells <br /> MW-4, MW-5, and SB-1. Based on recently measured groundwater elevations <br /> (December 8, 1994), groundwater flow in the shallow water-bearing zone is inferred to be <br /> bi-directional. Well SB-1 is located hydraulically upgradient of wells MW-4 and MW-5, <br /> and is currently monitored only for quarterly water-level measurements. It was installed to <br /> provide the third data point required for groundwater flow characterization. <br /> WDR Order No. 94-259 Monitoring and Reporting Program requires surface water <br /> samples to be collected from Corral Hollow Creek at locations upstream (SW-1) and <br /> downstream (SW-2) of the landfill facility after the first storm of the rainy reason which <br /> produces significant flows, and quarterly thereafter when water is present. <br /> The EMP (EMCON, 1993) was designed to evaluate changes in water quality due to the <br /> release from the northeastern portion of the landfill. The EMP proposed that the existing <br /> monitoring program be expanded by collecting groundwater samples on a quarterly basis <br /> instead of annually for well MW-5. The EMP also included quarterly monitoring for <br /> VOCs and the other parameters listed in the WDR from well SB-1. Samples will be <br /> collected and analyzed consistent with the analytical scope described below and the <br /> sampling and analysis procedures described in the EMP and included in Appendix D. This <br /> EMP supplements the monitoring program in the WDR with the following additions: <br /> • Well MW-5 is monitored for VOCs by EPA 601 on a quarterly basis as opposed <br /> to annually. <br /> SAC-\N.PJOM39\09390031.9BG-94\s :l Rev.0,420/95 <br /> 0939-003.19 6-1 <br />