In general, the Triad uses the term "uncertainty" to refer to things that are unknown to a greater or lesser degree. Uncertainty management begins with obtaining clarity among all involved parties about the goals and decisions for a particular project. Management of decision uncertainty depends on managing the uncertainty in the conceptual site model that will be used to support decision-making, usually through the collection of environmental data. Uncertainty in data generation is managed by controlling all relevant sampling and analytical factors that introduce confounding variability into data results.

Every cleanup decision has some uncertainty associated with it due to an inherent incomplete understanding of actual site conditions. For example, there is always the possibility that some unit of soil that is contaminated above cleanup guidelines will be missed by characterization and remediation work. Conversely, experience has shown that remedial activities often inadvertently capture and treat material that probably already met cleanup criteria. Uncertainty management is the attempt to manage or control decision-making uncertainty so that decisions can be made with an acceptable level of confidence. Uncertainty management usually includes collecting additional information about the contamination status of a site or portions of a site so that unacceptable uncertainty can be resolved. This is where dynamic work strategies and real-time measurement systems become important. The Triad provides an efficient and effective means for managing decision-making uncertainty through the affordable gathering of additional information.

Under Triad, uncertainty can be managed qualitatively through professional judgment or a weight of evidence approach, or through quantitative means such as statistical hypothesis testing. The level of decision confidence to be achieved, and how that confidence will be demonstrated, is determined during systematic planning with the input, and hopefully consensus, of project participants.