The recent surge in real estate sales and values has prompted developers and speculators to take a second look at properties with environmental problems. In some cases the problems are mitigated and the properties redeveloped under the umbrella of broad-scoped government programs that offer financial reimbursement for some or all of the cleanup costs (e.g. the New York State Brownfield Cleanup Program). Still the majority of these properties are mitigated in case-specific regulatory programs that are ultimately financed by the real estate equity. In both cases, it is often impractical to restore the site to ambient conditions. Rather, cleanup is pursued to a de minimis level that will restore property value and maintain a low-risk to occupants and the environment. This is often achieved by the design and implementation of a remedial program that administratively controls site land-use and physically removes exposure pathways (such as vapor intrusion), in lieu of the removal of the full body of contaminated media from a property.

In this capacity, controlling site land-use is termed an Institutional Control. An Institutional control means any non-physical means of enforcing a restriction on the use of a property that limits human or environmental exposure, restricts the use of groundwater, provides notice to potential owners, operators, or members of the public, or prevents actions that would interfere with the effectiveness of a remedial program or with the effectiveness and/or integrity of operation, maintenance, or monitoring activities at or pertaining to a remedial site. Often such restrictions are entered onto the title of the property as a deed restriction.

Removal of exposure pathways is considered an Engineered Control. Strictly defined, an Engineered Control means any physical barrier or method employed to actively or passively contain, stabilize, or monitor contamination, restrict the movement of contamination to ensure the long-term effectiveness of a remedial program, or eliminate potential exposure pathways to contamination. Engineering controls include, but are not limited to, pavement, caps, covers, subsurface demarcation barriers, vapor barriers (that prevent vapor intrusion), slurry walls, sub slab depressurization systems, building ventilation systems, fences, access controls, water control provision of alternative water supplies via connection to an existing public water supply, adding treatment technologies to such water supplies, and installing filtration devices on private water supplies.