Report of Field Investigations Assessment and Proposed Decision Document for theNorthwest Boundary System, Short-Term Improvements, Interim Response Action, RMA

摘要

Recent field investigations identified a small alluvial channel immediatelynortheast of the existing Northwest Boundary System (NWBS) that provides a pathway for ground water to flow around the slurry wall. Samples from this channel contained dieldrin at levels above the ARAR's for the north boundary system. The objective of the Northwest Boundary System short term improvements interim response action is to mitigate the bypass of contaminated alluvial ground water by extending the NWBS. The extension is to utilize methods employed to construct the existing system (dewatering wells, recharge wells, and/or a slurry wall). The treatment of extracted ground water will be performed by the existing treatment plant. This combined assessment and decision document provides information on: (1) Field investigations including borelogs and grain size reports; (2) Hydrogeology of the area; and (3) Ground water quality and level. (MM).