Site closure and productive reuse is the ultimate goal for every hazardous waste site. Site closure implies the ability to demonstrate with a reasonable level of confidence that a site has attained its specified cleanup criteria. This demonstration is based on the results of data collection programs. The results from these data collection efforts may be compared directly to cleanup standards, and/or may form the basis of a post-remediation risk assessment to establish that site-specific risk goals have been met.
The Triad approach has a role to play in final site closure. Cheaper, real-time methods can be used to screen individual locations for egregious contaminant concerns (i.e., hot spots), allowing a sampling density that is both cost-effective and sufficient for hot spot detection. These techniques can also be used to "pre-certify" or "pre-validate" that a particular area will meet cleanup criteria, before additional expense is incurred in more expensive and rigorous laboratory analyses that would feed risk calculations.