Thorough assessments and investigations are critical in understanding plant operations, manufacturing processes, and the potential hazards associated with decommissioning and demolition (D&D) activities. Characteristics and conditions of existing structures and site features must be well documented during assessments and investigations. CDM experts address sampling plans and data management, regulatory notification issues, identification of hazards and high-risk substances, specific building materials, and residues and waste materials that may require sampling and analysis to better define D&D costs, and streamline the overall D&D approach.