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3 TECHNICAL EVALUATION OF UPGRADIENT MONITORING WELLS The current wells potentially considered for use as upgradient monitoring points include MW-5, MW-6, MW-7 and MW-8. The WDR specifies MW-5 as the upgradient well but also requires an evaluation of the appropriateness of this designation. The following table presents the original breakdown of site strata defined by Kleinfelder and the zone accessed by each of the existing wells at the site. Monitoring Well Zone Hydrologic Layer Lithology Screened in Interval I Vadose Zone Clay and Silt MW-5 II Vadose Zone (Semi-Confining Unit) Clay III Uppermost Water Bearing Unit Fine Sand to Silty MW-6 8,MW-7 (Aquifer) Sand IV Aquitard Clay and Silt V Lower Aquifer (Semi-Confined) Sand MW-2A, MW-3A, MW-8, & MW-9A Figure 2 illustrates the existing monitoring well network. The following subsections discuss the status of the wells at the Site. 3.1 MONITORING WELL MW-5 Monitoring Well MW-5 was originally installed to monitor the shallowest occurrence of groundwater at the Site and is approximately 28 feet deep. The interval of saturated soil accessed by MW-5 was only encountered in the area of MW-5, was defined by Kleinfelder as "Zone 1", and was interpreted to be within the vadose zone. Because the occurrence of groundwater at this level is unique to this specific area, the chemistry of this water cannot be appropriately compared to wells accessing water from deeper,separate zones. The proximity of MW-5 to Duck Creek suggests that water in this zone is likely related to lateral infiltration from Duck Creek. The chemistry of the water in Duck Creek is related to the runoff it carries, which is sourced from a large drainage to the east, including agricultural and industrial sites upgradient of the site. Because the water within MW-5 is suspected of receiving influence 3 AW t F0 BRlOI�KS .?ae. P:\707 Cove Contractors\WDR\Tech Report and WP 2008\Tech Report and WP_PINAL.doc