The ''Initial Single-Shell Tank System Performance Assessment for the Hanford Site [1] (SST PA) presents the analysis of the long-term impacts of residual wastes assumed to remain after retrieval of tank waste and closure of the SST farms at the US Department of Energy (DOE) Hanford Site. The SST PA supports key elements of the closure process agreed upon in 2004 by DOE, the Washington State Department of Ecology (Ecology), and the US Environmental Protection Agency (EPA). The SST PA element is defined in Appendix I of the ''Hanford Federal Facility Agreement and Consent Order'' (HFFACO) (Ecology et al. 1989) [2], the document that establishes the overall closure process for the SST and double-shell tank (DST) systems. The approach incorporated in the SST PA integrates substantive features of both hazardous and radioactive waste management regulations into a single analysis. The defense-in-depth approach used in this analysis defined two major engineering barriers (a surface barrier and the grouted tank structure) and one natural barrier (the vadose zone) that will be relied on to control waste release into the accessible environment and attain expected performance metrics. The analysis evaluates specific barrier characteristics and other site features that influence contaminant migration by the various pathways. A ''reference'' case and a suite of sensitivity/uncertainty cases are considered. The ''reference case'' evaluates environmental impacts assuming central tendency estimates of site conditions. ''Reference'' case analysis results show residual tank waste impacts on nearby groundwater, air resources; or inadvertent intruders to be well below most important performance objectives. Conversely, past releases to the soil, from previous tank farm operations, are shown to have groundwater impacts that re significantly above most performance objectives. Sensitivity/uncertainty cases examine single and multiple parameter variability along with plausible alternatives to ''reference'' cases to judge how the proposed closure system performs when changes to important assumptions are made to the hydrogeologic and engineered systems. The estimated impacts from these cases are generally consistent with ''reference'' case results (i.e., performance objectives are exceeded by contaminants from past releases but not tank residuals). This document and its future iterations will play a critical role in the decision making process for the closure of the Hanford Tank Farms. It will support interim decisions related to tank retrievals and interim corrective measures, in addition to supporting the major closure decisions of tanks and tank farms. Hence, it is imperative that the review process of this document is inclusive of the decision makers as well as the Hanford Stakeholders.

Remediation of Legacy Hazardous and Nuclear Industrial Sites provides an overview of the key elements involved in remediating complex waste sites using the Hanford nuclear site as a case study. Hanford is one of the most complex waste sites in the world and has examples of most, if not all, characteristics of the complex waste sites that exist globally. This book is aimed at a non-technical audience and describes the stages of remediation based on general RCRA/CERCLA processes, from establishing a strategy that includes all stakeholders to site assessment, waste treatment and disposal, and long-term monitoring. Features: Informs a non-technical audience of the important elements involved in complex waste site remediation Employs the Hanford Site as a case study throughout to explain real-world applications of remediation steps Connects the “human” element to the technical aspects through interviews with key current and retired individuals at the Hanford Site Includes discussion of stakeholders and the engagement process in remediation Demonstrates how all elements of complex waste site remediation from demolition of buildings to groundwater management are interrelated Focuses on broader technical and sociopolitical challenges for remediation of a contaminated site Aimed at a broad audience, this book offers approachable guidance to technical and non-technical readers through a series of real-world examples that cover each important step in the complex waste cleanup process.