Institutional controls for brownfields relate to a concept that has evolved during the last ten years, and continues to change. This evolution started soon after risk-based closure concepts found their way into state voluntary cleanup programs. Risk-based closures result in exit strategies for site cleanup that protect human health and the environment, but do not necessarily restore a site to a pre-contaminated condition. Therefore, since the closed site may have some level of residual chemical constituents after remedial actions, land use controls are frequently placed on a site to limit the future use to risk-use scenarios on which the closure was based.

These land use controls (LUCs), referred to in some states as “environmental land use controls” or ELUCs, are typically composed of institutional controls and/or engineered barriers. Institutional controls usually refer to regulatory methods to maintain closure site conditions, whereas engineered barriers usually refer to physical methods to control access to residual chemical constituents remaining on a site.

Engineered Barriers
Engineered barriers control access to chemical constituents that may remain on a site after risk-based cleanup. Risk-based solutions in many states consider various scenarios for the protection of human health and the environment. These scenarios may include the potential for soil contact, soil or groundwater ingestion, inhalation of vapors from the soil, or the effects of soil contamination on the groundwater.  

Different physical methods can be applied to mitigate the potential impact of various risk-based cleanup scenarios. For example, soil vapors may migrate through relatively thick zones of soil, so a barrier to mitigate potential vapor effects may be significant (e.g., several feet of soil to stop the migration of vapors). On the other hand, stopping a site visitor or worker from contacting a soil that has residual chemical constituents may simply be an existing asphalt parking lot or a few feet of landscaping soil.

Some states have regulations that define requirements for engineered barriers. These requirements usually specify different barriers for each risk-based condition (e.g., groundwater control systems, various thicknesses of concrete, asphalt, low-permeability compacted soil, general soil or other materials).

Barrier requirements, though similar, vary from state to state. Typical soil-related barriers include:

• 6 to 12 inches of asphalt pavement and base course to minimize soil contact
• 4 to 6 inches of concrete floor or pavement to minimize soil contact
• 3 feet of “clean” soil to minimize soil contact
• Geomembranes and applied pliable layers under floor slabs to minimize vapor intrusion
• 5 to 10 feet of soil to minimize vapor migration.

An ASTM committee is drafting a “Standard Guide for Application of Engineering Controls to Facilitate Use or Redevelopment of Chemically Affected Properties.” According to Exxon-Mobil’s Mark Milander, head of the committee, “The standard is intended to assist...in implementing appropriate engineering controls and construction measures to facilitate continued property use or redevelopment.” The guide will propose definitions, conditions for use, typical material types and thicknesses, and installation requirements.  The target date for the standard is in 2004.

Institutional Controls
Institutional controls apply regulations to maintain site closure conditions. They most often take the form of either local ordinances or deed restrictions. An example of a local ordinance is the prohibition on the use of groundwater at a property for potable use. Restricting on-site groundwater to non-potable uses eliminates the risk of public ingestion of water that may potentially have low chemical concentrations.

Deed restrictions are the other main type of institutional control. Risk-based solutions frequently specify the end use of a property. This is because the risk to the public varies related to end use. For example, a property planned for residential purposes has the potential for frequent soil contact and ingestion (e.g., gardens, play areas) whereas a property used for commercial or industrial purposes has less potential for frequent soil contact and ingestion. A deed restriction records a limitation for the use of the property on the property’s deed.

This limitation can take the form of a prescribed occupancy use, prescribe the requirement for an engineered barrier, or identify a necessary condition of use (e.g., prescribe that a health and safety plan is necessary for workers involved in utility construction, or that a groundwater pumping system is necessary to control groundwater gradients).

The Future of Institutional Controls
Institutional control technology will continue to evolve as requirements are promulgated and implemented in each state. The main issue to be resolved is how to be sure that a control is maintained once implemented or filed on the deed. There have been numerous instances where a restricted use has been specified and agreed to by the regulators, but has been circumvented, either purposely or inadvertently, by the subsequent site user. This overarching issue is being given significant attention by interested parties.

At least eight different sessions at the EPA-sponsored National Brownfields Conference in Portland, Oregon in October 2003, dealt with establishing and maintaining institutional controls. Issues discussed included:

• How to be sure that the restrictions have actually been recorded on the deed,
• How restriction records can be communicated so incidental users (e.g., pipelines crossing the property) will be aware of the restrictions,
• How to identify who pays for the programs to maintain and communicate records,
• Is there a way that a uniform environmental deed restriction process, one that embraces historic legal precedence related to buying and selling a property, can be implemented, and
• What are the respective roles and responsibilities of parties involved in the institutional control process?

There is a significant initiative by the National Conference of Commissioners on Uniform State Laws (NCCUSL) to develop and adapt a nationwide Uniform Environmental Covenant Act (UECA). In August 2003, the UECA was approved by the NCCUSL after a two-year drafting process. The covenant does not specify levels of cleanup or risk-based approaches, but provides a method of dealing with historic legal precedence related to property sale and purchase.

A number of initiatives dealing with record keeping to tracking institutional controls were presented at the Portland Conference. including computer-based record keeping systems. One, a joint project by the California EPA and Terradex, Inc., is a system that logs properties in a GIS database that is linked to a local utility clearance system. In the same way that a contractor finds out that there is a gas or water pipeline on a site under construction, the contractor can find out that the property has a deed restriction that requires a worker health and safety plan before excavating. Another joint initiative developed a process whereby a city development department coordinator is engaged prior to receiving a building permit. The department coordinator identifies specific construction requirements in the permit. The remediation site owners funded the coordinator’s costs.

Resolution of the technical issues related to implementation of institutional controls is still in the development stage. It will likely take several years, and some difficult lessons, before all stakeholders reach clear resolution, largely because of the complexity of the issue rather than a lack of desire for resolution.