As part of the license termination process, site-specific Derived Concentration Guideline Levels for the Haddam Neck Plant site are developed for soil, groundwater, concrete left standing, and concrete demolished that satisfy the radiological criteria for unrestricted use as defined in 10 CFR 20.1402. Background information on the license termination process and characteristics of the Haddam Neck Plant site are presented. The dose models and associated resident farmer and building occupancy scenarios, applicable pathways, and critical groups developed to establish the Derived Concentration Guideline Levels are described. A parameter assignment process is introduced wherein general population values are used to establish behavioral and metabolic parameters representative of an average member of the critical group, while the uncertainty associated with important physical parameters is considered. A key element of the parameter assignment process is the use of sensitivity analysis to identify the dose sensitive physical parameters and to ensure that such parameters are assigned conservative values.