A brownfield site is real property where expansion, redevelopment, or reuse may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant. Historically, these properties were often used for industrial or commercial purposes, resulting in a legacy of environmental uncertainty. These sites are typically abandoned or underutilized, representing a significant environmental and economic challenge for communities. Returning these properties to productive use requires specialized assessment and cleanup.
Defining a Brownfield Site
The official designation of a brownfield site focuses not only on known contamination but also on the potential presence of hazardous substances, pollutants, or contaminants. This uncertainty alone can halt property transactions and development, necessitating investigation before reuse is possible. Brownfield sites are often located in urban or developed areas, where they represent blight and limit economic growth.
A defining characteristic is that brownfields generally involve contamination that is less severe and more localized than other hazardous sites. This distinction separates them from Superfund sites, which require extensive, long-term federal cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Brownfield cleanup is typically managed at the state or local level, often through voluntary cleanup programs, making redevelopment more accessible for private entities and communities.
Brownfield sites must also be clearly differentiated from greenfield sites, which are undeveloped land that has never been used for industrial or commercial purposes. Redeveloping existing brownfield infrastructure is often more sustainable than building on untouched greenfields. The federal government estimates there are over 450,000 brownfields across the United States, representing a vast reservoir of land ready for revitalization.
Common Sources of Contamination
The contamination found on brownfield sites is a direct result of past industrial or commercial activities on the property. Specific former land uses frequently associated with brownfields include abandoned factories, old railroad yards, metal plating facilities, and chemical processing plants. Commercial operations like former gas stations, auto repair garages, and dry cleaners also commonly lead to brownfield designation due to leaks or improper disposal practices.
The types of contaminants found are varied, but several classes of hazardous substances are frequently identified. Understanding the specific history of the site is paramount in predicting the types of contamination present.
Common Contaminants
Common contaminants frequently identified include:
- Heavy metals such as lead and arsenic, often used in manufacturing, paints, and pesticides.
- Petroleum products, including hydrocarbon compounds, common pollutants from storage tanks and refining operations.
- Volatile organic compounds (VOCs), which are industrial solvents and degreasers used in manufacturing and dry cleaning processes.
- Polychlorinated Biphenyls (PCBs), used in electrical equipment and hydraulic fluids.
- Asbestos, used for insulation and fireproofing.
The Process of Assessment and Remediation
Once a brownfield property is targeted for reuse, the first practical step is the Environmental Site Assessment (ESA) process. This begins with a Phase I ESA, a non-intrusive investigation designed to identify the potential for contamination. Environmental professionals review historical records, conduct a visual inspection of the site and adjacent properties, and interview people knowledgeable about the property’s past use.
The Phase I ESA aims to identify Recognized Environmental Conditions (RECs), which are indications of possible contamination, without physical sampling. If RECs are identified, a Phase II ESA is typically recommended to confirm the presence and extent of the contamination. The Phase II ESA is an intrusive process involving the physical collection of samples of soil, groundwater, and sometimes soil vapor from targeted locations on the property.
These samples are then sent to a laboratory for detailed analysis to determine the type and concentration of hazardous substances. The results guide the next step: remediation, or cleanup. Remediation techniques are specific to the type of contaminant and the intended future use of the land, as residential standards are generally much stricter than industrial standards.
Common remediation techniques include excavation, where contaminated soil is dug up and removed for off-site treatment or disposal. Other methods are in situ (on-site) treatments, such as bioremediation, which uses microbes to break down organic contaminants into less harmful substances. Capping involves placing a barrier, such as clean soil or pavement, over the contaminated area to prevent human exposure. Regulatory oversight from state and local environmental agencies ensures the cleanup meets the standards necessary for the proposed end use.
Economic and Community Impact of Redevelopment
The successful redevelopment of brownfields provides significant societal benefits. By reusing land within developed areas, brownfield projects promote infill development and directly reduce urban sprawl, preserving undeveloped greenfield land. The reuse of existing infrastructure, including roads and utilities, provides cost savings compared to new development on the outskirts of a community.
Economically, brownfield revitalization generates new revenue streams for local governments. The cleanup and subsequent operation of new businesses on the site create jobs, while transforming unproductive land leads to a substantial increase in the local property tax base. Studies have shown that residential property values within a mile of a remediated brownfield can increase by five to fifteen percent.
Revitalization also improves public health and the overall quality of life for residents. Removing hazardous materials, such as lead and asbestos, eliminates potential exposure pathways, especially for sensitive populations. Furthermore, redeveloping abandoned properties removes blight, creating opportunities for new public spaces, housing, and commercial centers that revitalize neighborhoods and enhance community image.