Brownfield remediation transforms properties contaminated by hazardous substances. These sites are often abandoned or underused, posing redevelopment challenges. Environmental remediation involves removing or containing harmful substances from soil, groundwater, and sediment to restore areas to a safe, usable state. This process mitigates environmental effects and protects human health.
Identifying a Brownfield Site
A brownfield site is previously developed land that is abandoned or underused due to contamination concerns. These properties are often in urban or suburban areas, formerly used for industrial, commercial, or manufacturing purposes. Examples include former factories, gas stations, dry cleaners, and landfills.
Contaminants vary based on past activities. Common hazardous substances include heavy metals like lead, mercury, cadmium, and arsenic, often from manufacturing or mining. Petroleum hydrocarbons, such as oil, gasoline, and diesel, are frequently present from former gas stations or transportation hubs. Other contaminants are solvents like trichloroethylene, asbestos from older building materials, and polycyclic aromatic hydrocarbons (PAHs).
The Remediation Journey
Brownfield remediation begins with a thorough site evaluation to understand its environmental history and contamination risks. This starts with a Phase I Environmental Site Assessment (ESA), involving historical research and visual inspection to identify potential contamination. If contamination is suspected, a Phase II ESA follows, including sampling and testing of soil, groundwater, and sometimes building materials to confirm and delineate the extent of contamination.
After investigations, a Remedial Action Plan (RAP) is developed, outlining cleanup methods and future use goals. The implementation phase involves the actual cleanup, using various technologies based on contaminants and site conditions. Regulatory bodies, like the U.S. Environmental Protection Agency (EPA), oversee the process for compliance. The process concludes with verification, ongoing monitoring, and regulatory closure, ensuring the site meets standards for its intended reuse.
Strategies for Cleanup
The selection of a specific cleanup strategy for a brownfield site depends on factors such as the type and concentration of contaminants, site conditions, and the planned future use of the property. These strategies aim to address contamination effectively while considering the site’s future purpose. Three primary approaches are containment, removal, and treatment.
Containment
This approach involves placing barriers or caps to prevent contaminants from spreading. Examples include creating a layer of clean soil or a geotextile barrier over contaminated areas.
Removal
Contaminated materials are excavated and transported off-site for disposal or treatment. This method is often used for contaminated soil or the removal of underground storage tanks and associated piping.
Treatment
Treatment methods aim to transform or degrade contaminants, either in place (in-situ) or after removal (ex-situ). In-situ treatments might involve injecting chemicals into the soil to break down harmful substances. Bioremediation uses naturally occurring or introduced microbes to consume organic contaminants. Phytoremediation employs plants to absorb contaminants or release substances that neutralize them. Ex-situ treatment involves excavating contaminated material and treating it on the surface before disposal or reuse.
The Value of Revitalizing Brownfields
Revitalizing brownfield sites offers multiple benefits for communities, encompassing environmental protection, economic growth, and community improvement. Cleaning up these sites directly improves local environmental quality by remediating contaminated soil and water, thereby reducing exposure to hazardous substances. This also helps preserve undeveloped greenfield land by promoting infill development and reducing urban sprawl.
From an economic perspective, brownfield redevelopment creates new jobs and attracts private investment. Successful cleanup projects can increase property values in and around the remediated sites, sometimes by 5% to 15.2% within a mile of the site. This increased property value can generate additional local tax revenue, contributing to the economic vitality of an area.
Community revitalization is another significant outcome, as brownfield cleanup transforms neglected areas into productive spaces. This can include creating new commercial, residential, or recreational opportunities. The process helps eliminate visual blight and improve public health and safety by removing contamination risks.