A brownfield is a property whose redevelopment or reuse is complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant. These sites are often abandoned or underused former industrial or commercial facilities that carry a stigma of environmental risk. The main challenge is not always proven contamination, but the uncertainty and potential liability that the perceived risk introduces. Reclaiming these properties is an important part of urban renewal and environmental protection.
What Makes a Site a Brownfield
The definition of a brownfield, as established by the U.S. Environmental Protection Agency (EPA), centers on the complication of reuse due to a hazardous substance. This formal designation is distinct from a more severely contaminated Superfund site. Brownfields typically present a less immediate or complex threat than the sites listed on the National Priorities List (NPL), which require extensive federal intervention.
Many brownfields are remnants of past economic activity where chemicals were handled without modern environmental safeguards. Common historical uses resulting in this designation include:
- Former gas stations with leaking underground storage tanks.
- Dry cleaners that used solvents.
- Various manufacturing plants.
- Railroad facilities, abandoned mines, and older residential areas with lead-based paint or asbestos.
Contaminants frequently found are petroleum products, heavy metals like lead and arsenic, and volatile organic compounds (VOCs).
The contamination can be actual or merely potential, which is why the perceived risk alone can deter new investment. This perception of risk, coupled with liability concerns, often leaves brownfields vacant, preventing economic activity. The less severe nature of the contamination, compared to Superfund sites, makes brownfields more amenable to local and state-driven cleanup and redevelopment efforts.
Investigating and Remediating Contamination
Before any physical cleanup can begin, an environmental investigation must be completed to define the nature and extent of the contamination. The first step is typically a Phase I Environmental Site Assessment (ESA), a non-intrusive historical review of the property. This assessment involves examining past land use records, regulatory databases, and conducting a visual site inspection. The goal of the Phase I ESA is to identify recognized environmental conditions (RECs), which are potential sources of contamination, without collecting physical samples.
If a Phase I ESA identifies RECs, a Phase II ESA is required to confirm the presence of hazardous substances. The Phase II investigation is intrusive, involving the collection of soil, groundwater, and soil vapor samples from the site. These samples are analyzed in a laboratory to determine the type, concentration, and extent of any contaminants present. The results of the Phase II ESA drive the selection of a specific cleanup method, known as remediation.
Remediation techniques are specialized and depend on the contaminants and the planned future use of the site. Common physical methods include soil excavation, where contaminated soil is transported off-site for disposal or treatment, and capping. Capping involves installing a barrier, such as clean soil or pavement, over the contaminated area to prevent exposure. For organic contaminants like petroleum, bioremediation uses naturally occurring microbes to break down the pollutants into less harmful substances. Other in-situ methods include chemical oxidation or the use of permeable reactive barriers to treat contaminated groundwater.
Repurposing Brownfield Sites
Successful remediation clears the way for brownfield revitalization: returning the land to productive use. Redeveloping these sites is environmentally preferable to building on undeveloped land, known as greenfields, as it curbs urban sprawl and preserves natural habitats. Transforming a brownfield also provides economic advantages by increasing property values, boosting local tax revenue, and creating jobs.
Repurposed brownfields can take many forms, transforming liability into community assets. Common redevelopment outcomes include:
- Commercial spaces, such as offices and retail centers, and new housing.
- Public green spaces, including parks, community gardens, or recreational trails.
- Renewable energy installations, such as solar farms, utilizing existing infrastructure.
To encourage this transition, federal and state programs offer financial and technical support to offset cleanup costs and risks. The EPA Brownfields Program provides grants to communities and developers for assessment and cleanup activities, facilitating private investment. This support helps transform these complex sites into functioning parts of the community, maximizing the use of existing urban infrastructure.