The use of institutional and engineering controls has increased at the federal, state, and local levels as part of remediation programs to achieve site closure and subsequent land reuse. In most cases, substantial cleanup savings can be achieved by tailoring site closure reuse with the use of institutional and engineering controls.
Site cleanup can be an expensive endeavor and requires proper planning and budgeting, extending far beyond physical contaminants themselves. In instances where cleanup is not cost effective, the next step begins with gaining a clear understating of how institutional and engineering controls (IC/EC) affect the process of achieving site closure.
Site closure is the point in time when the site owner or operator is released from further site-care responsibilities and the area is considered safe for reuse/redevelopment under a commercial or residential scenario. Environmental professionals achieve closure through a series of controls, authorized by federal and state regulations through a process called Risk Based Corrective Action (RBCA), which allows for managing the risk that a contaminant may pose to a potentially exposed sensitive receptor.
One of the first steps in any environmental cleanup project is developing a conceptual site model (CSM). As part of the site-closure process, consultants must develop a CSM to allow for a more holistic view of potential exposure pathways and receptors. Once these pathways and associated risks are determined, IC/EC controls may be applied towards site closure based on their ability to mitigate risk of exposure to groundwater, soil, surface water, or sediment.
Institutional controls (IC) are defined as “durable” or “go-with-the-land” legal controls that minimize potential human contamination exposure by limiting or restricting the access and/or use of land or resources such as groundwater. Engineering controls (EC), on the other hand, consist of engineering measures—such as asphalt/concrete caps, buildings, parking lots, or treatment systems—used to minimize human exposure to contamination by limiting direct contact with the contaminated area.
It is helpful to examine each control separately to better understand how they work toward successful site closure both individually and in tandem.
Institutional Controls (ICs)
ICs are used to manage risk of exposure or to control completed exposure pathways. These are legally durable and come in several varieties. In general, these controls will be mentioned in a site closure order or be recorded as deed covenants to protect the integrity of the site’s chosen mitigation remedy.
Examples of Common ICs
- Deed restrictions on accessing soil and groundwater/land use
- Municipal ordinances requiring connection to a municipal potable water supply
- Government-issued wellhead protection areas
- Promulgated building codes requiring connection to a municipal water supply
- Specific institutional restrictions such as an airport/seaport prohibiting tenants from unauthorized groundwater use
- Restrictions on installing water wells in contaminated aquifers
- City/county zoning restrictions limiting land use to commercial vs. residential use
- Fishing bans
Using these ICs alone or in combination goes a long way in eliminating exposure to contaminated sites and achieving a cost-efficient site closure. The Environmental Protection Agency (EPA) recognizes that when properly implemented and maintained, ICs are an effective means of exposure pathway restriction or elimination and lead to productive land reuse.
Engineering Controls (EC)
ECs are physical barriers that actively or passively control contamination by stabilizing, monitoring, or eliminating the spread of contamination throughout the remedial process. For various reasons—such as cost-effectiveness—it may be advisable to leave site contamination in place. ECs can be useful in these scenarios to act as a mechanism to prevent contact with or movement of contamination, particularly in soil or groundwater.
For example, sub-slab depressurization systems (SSDS) are often used to address soil vapor contamination and vapor intrusion. Another common EC for soil is an impermeable surface covering such as a cap or paved surface. These physical methods can be used both to control contamination and protect the public and must be maintained and monitored for integrity by the site owner following site closure.
If engineering controls such as barriers, caps, or fences are used as part of the remedial and site closure strategy, the deed restriction requires that these engineering controls be maintained for as long as contamination below the EC remains. For example, if a cap was used to eliminate exposure, that cap would be required to be maintained by the property owner to ensure that the exposure pathway remains incomplete, even following site closure.
Examples of Common ECs
- Site covers or caps
- Subsurface barriers
- Vapor barriers
- Slurry walls
- Ventilation systems
- Fence installation (limiting public access)
Dual-Use of IC/EC for Site Cleanup and Reuse
While both ICs and ECs are effective methods on their own, many successful remediations utilize both institutional and engineering controls to facilitate site closure and redevelopment. This is particularly critical as the EPA considers a proposal to designate per-and polyfluoroalkyl substances (PFAS) as hazardous substances under CERCLA. Specific institutional and engineering controls may require consideration for a site owner to restrict PFAS exposure pathways and achieve site closure.
Mitigate Risk with a Trusted Advisor
Achieving site closure by using IC/ECs is a multi-faceted procedure that requires foresight and a unique understanding of environmental regulations. Third-party consultants are instrumental in using IC/ECs for cost-efficient site cleanups that are tailored to the site’s future reuse.
Cameron-Cole, for example, closed more than 10 sites in 2022 and 2023 using IC/ECs and gives you access to a team of experts with the knowledge to help you understand what controls are right for your project.
Cameron-Cole, an ADEC Innovation, specializes in assisting our clients with complex environmental liabilities through environmental remediation. Contact us for a free consultation to discuss your current and potential remediation obligations and whether IC/ECs can be used to manage costs and achieve site closure.