Combination RCRA groundwater monitoring plan for the 216-A-10, 216-A-36B, and 216-A-37-1 PUREX cribs

This document presents a groundwater quality assessment monitoring plan, under Resource Conservation and Recovery Act of 1976 (RCRA) regulatory requirements for three RCRA sites in the Hanford Site`s 200 East Area: 216-A-10, 216-A-36B, and 216-A-37-1 cribs (PUREX cribs). The objectives of this monitoring plan are to combine the three facilities into one groundwater quality assessment program and to assess the nature, extent, and rate of contaminant migration from these facilities. A groundwater quality assessment plan is proposed because at least one downgradient well in the existing monitoring well networks has concentrations of groundwater constituents indicating that the facilities have contributed to groundwater contamination. The proposed combined groundwater monitoring well network includes 11 existing near-field wells to monitor contamination in the aquifer in the immediate vicinity of the PUREX cribs. Because groundwater contamination from these cribs is known to have migrated as far away as the 300 Area (more than 25 km from the PUREX cribs), the plan proposes to use results of groundwater analyses from 57 additional wells monitored to meet environmental monitoring requirements of US Department of Energy Order 5400.1 to supplement the near-field data. Assessments of data collected from these wells will help with a future decision of whether additional wells are needed