The Hanford Environmental Dose Reconstruction (HEDR) Project has developed a set of computational "tools" for estimating the possible radiation dose that individuals may have received from past Hanford Site operations. This document describes the planned activities to "validate" these tools. ,In the sense of the HEDR Project, "validation" is a process carried out by comparing computational model predictions with field observations and experimental measurements that are independent of those used to develop the model. ScopeA high level of coverage of the various space/time/pathway combinationsused in the primary dose calculations would lead to the most rigorously defensible validation. Data are not available to support such an ambitiousvalidation program. Contemporaneousdata do not addressali the necessary pathways, over space or over time, needed to provide a complete validation. The data sets that have been selected for validation were chosen to providethe best examples of coverage of the domain in time, in space, and for as many pathways as possible. ApproachThe general philosophy of this plan is to comparethe calculated values of dose, or of the surrogatemeasurementclosest to dose available(e.g., concentrationsof radioiodine in sagebrush), with the measurements. The purpose is primarily to characterize the comparisonswith respect to the spatial, temporal, or pathway elements of the availabledata. The approachis to provide descriptive statistics, rather than formal "hypothesis testing" statistics. ResultsThis report discusses the data sets available to address the general validation goals. Fourteen specific procedures are provided to be used to prepare the existing data sets, estimate environmental contamination levels or doses, and compare the observed and predicted data. Comparison of the HEDR models is described through benchmarking with other international models in the International Atomic Energy Agency's Coordinated Research Program on Validation of Radionuclide Transport Models for Terrestrial, Urban, and Aquatic Environment. A generic description of deliverables of b each individual validation exercise is provided. Future uses of the validation results are addressed. Projected schedule and costs of performing these analyses are provided.