Institutional controls are legal or administrative tools to prevent unacceptable exposures to contamination left in place at the completion of removal or remedial actions. Common examples are restricting groundwater use or preventing residential uses of a property.
Engineering controls are physical measures that are also designed to prevent or minimize exposure to hazardous substances remaining on-site. Engineering controls may include such measures as fencing, capping, horizontal or vertical barriers, hydraulic controls, or provision of clean water supplies.
Typically, the property owner agrees to accept and maintain institutional and engineering controls through an agreement with DEQ called an Easement & Equitable Servitude. The E&ES is registered with the county recorder and runs with the land, meaning that future owners must also abide by the controls. Institutional and engineering controls often require periodic inspections or maintenance to ensure they are still in place and working as designed.
DEQ's Environmental Cleanup Section has made many no-further-action determinations that depend on institutional and/or engineering controls to prevent unacceptable risks to humans or the environment.