Multidisciplinary Approach to Achievement of Risk-Based End-States for Facility Decommissioning at the Savannah River Site

P.L. Lee1; G.T. Jannik1; E.P. Shine1; K.L. Dixon1; J.L. Roach, Jr.2; T.O. Oliver2; R.C. Tuckfield1; and V.R. Fricke2 [1Savannah River National Laboratory (Westinghouse Savannah River Company); 2Closure Business Unit (Westinghouse Savannah River Company)]

In response to the request for accelerated cleanup at US Department of Energy (DOE) facilities, the Savannah River Site (SRS) is decommissioning radiological and chemical facilities through removal of the facility structures leaving concrete slab foundations in place. Decommissioning to a concrete slab end-state, when permitted to do so based on residual contamination, is cost effective and supportive of the accelerated effort. Existing SRS future land use plans indicate that DOE does not plan to release SRS areas to the public, but instead is using facility decommissioning to effect area closure through the Federal Facility Agreement process. A multidisciplinary approach is presented that demonstrates achievement of risk-based end-states through 1) human health risk assessment for future land use exposure scenarios, 2) evaluation of contaminant migration for potential impacts to groundwater, and statistical sampling for contaminant concentration measurements. Site-specific human health risk assessment methods are developed to demonstrate compliance with risk-based cleanliness criteria. Fate and transport modeling methods are applied to evaluate the potential for contaminants to adversely impact groundwater due to leaching from concrete slabs remaining after facility decommissioning. Statistical sampling designs are developed to provide a framework for selecting sampling locations that verify that contaminant removal from the selected facility has resulted in a concrete slab foundation with residual contamination that does not exceed the acceptable risk-based cleanliness criteria. Prepared for the U.S. Department of Energy in connection with work under contract #DE-AC09-96SR18500

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