Use of Institutional Controls to Facilitate Site Closure
Historically, the use of Institutional Controls (ICs) was associated with large, complex sites involved in U.S. Environmental Protection Agency (EPA) cleanup programs, such as Resource Conservation and Recovery Act (RCRA) Corrective Action and Superfund. The ICs were commonly used in conjunction with removal actions, soil and groundwater remediation, and risk assessment to reduce the potential for exposures over the long-term. However, the use of Institutional Controls in smaller-scale cleanups, such as state-led Leaking Underground Storage Tank (LUST) sites and state voluntary cleanup programs is now becoming commonplace. The increasing acceptance and use of ICs has allowed for increased flexibility with closures for both small and large sites, thus facilitating redevelopment activities.
What are Institutional Controls?
Institutional Controls are property or government controls that are used to manage risks or control completed or potentially completed exposure pathways. They are non-engineered instruments such as administrative and legal controls that help minimize the potential for human exposure to contamination and/or protect the integrity of a chosen remedy (USEPA, 2020).
Common ICs include deed restrictions on property (sometimes referred to as “restrictive covenants”) and environmental ordinances, which are implemented by a government agency (usually the local municipality or health department).
- Typical “deed restrictions” include:
- Prohibiting residential use on a property
- Prohibiting installation and use of potable groundwater wells
- Proper management of soils disturbed/removed as part of site work
- Proper vapor intrusion investigation/mitigation for occupied structures
- The most common environmental ordinances include:
- Prohibitions against the installation and use of potable water wells (sometimes referred to as a “groundwater ordinance” and it is the most commonly used environmental ordinance.)
- Other governmental controls such as zoning restrictions, fishing bans, and bans on groundwater or surface water use can also be used
Each of these ICs eliminates potential exposure to contaminated media. As a result, the ICs control the risk profiles for sites and can substantially reduce the actual risk to human health. The USEPA and state agencies recognize that ICs are considered an effective means of exposure pathway restriction or elimination, provided they are properly implemented and maintained.
The Use of Institutional Controls to Mitigate Identified Risks
One of the first steps in any environmental cleanup project is to develop a conceptual site model (CSM). The CSM allows one to look at a site holistically to understand the potential exposure pathways and receptors. The CSM should include an evaluation of current conditions as well as likely future conditions. Once exposure pathways and risks are assessed as part of the CSM, remedies are evaluated based on their ability to mitigate or eliminate risk. This evaluation includes active remediation techniques, such as soil excavation or in-situ groundwater treatment, as well as ICs that can be used to eliminate potential exposures.
ICs can be used in concert with active remediation and engineering controls (e.g., fencing, security, and barriers/caps) and risk assessment to ensure that there are no unacceptable exposures in the future. For example, a responsible party may opt to clean-up the soil and groundwater to a construction-worker or industrial standard, and restrict future property use to industrial or commercial using a restrictive covenant, thus prohibiting residential land usage and potential for residential exposures. Similarly, the potential for ingestion and direct contact of impacted groundwater can be eliminated by use of a deed restriction.
If engineering controls such as barriers, caps, or fences are used as part of the remedial strategy, the deed restriction would require that these engineering controls be maintained. For example, if a portion of the site utilized a cap to eliminate potential exposures, then the restrictive covenant would require that the cap be maintained by the property owner to ensure that the exposure pathway remains incomplete.
The use of ICs is a common strategy to ensure exposure pathways remain incomplete and to expedite site closure. The use of ICs, with or without engineering controls, should be part of the overall remedial evaluation and risk management strategy for a contaminated site. Continued refinement and the application of ICs allow risks posed by contaminated sites to be managed in a cost effective manner so that site closure can be achieved, which facilitates property redevelopment.