The U.S. Environmental Protection agency (EPA) estimates that upwards of 450,000 active brownfields have been identified in the United States. The definition of a brownfield is, “real property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant.” As noted by the EPA, the most common contaminants at these sites include lead, petroleum, and asbestos. Exposure to these chemicals presents significant health risks. Therefore, work is being done to appropriately clean up and redevelop these sites. However, the cost and potential liability associated with brownfields can be an impediment to cleanup, which often stifles the economies in low-income communities and urban centers where brownfields are seen at higher rates.
Discussions surrounding the spread of the perceived contaminants in the radial mileage surrounding the sites are limited. For instance, water from an intense storm event could potentially percolate through the known contaminated soils and leech pollutants into underground aquifers. The spread of these pollutants can also easily runoff into above ground channels and affect existing water infrastructure. As a primitive look into this idea, I used public GIS data of brownfield sites in Florida to investigate potential trends between poor water infrastructure and active sites. Quality tests of all water utilities in Florida are provided to the Environmental Working Group (EWG) by the Florida Department of Environmental Protection (FDEP) and displayed in the tap water database each year.
In 2019, the EWG noted that utilities with high violations were found in New Smyrna and West Palm Beach, FL. As shown in the figures above, densely spread brownfields are evident in both cities. It is important to note that the EWG standards are not the mandated regulatory limits for tap water quality, but rather are being used in this case for the purpose of identifying areas of concern. High levels of toxic chemicals listed in these standards are generally by-products of the above noted common contaminants found on brownfields. While these water quality issues may also be linked to other environmental and social factors and may not directly trace back to the brownfield sites, it is interesting to note the potential correlation to poor drinking water and septic systems.
Risk-based cleanup practices that focus on a property’s intended reuse are used to remediate these sites. Remediation techniques are applied to both soil and groundwater, though groundwater cleanup generally takes longer and is sometimes ineffective. The Green Building Alliance notes some of the following groundwater cleanup techniques:
- Pump and treat: the most common groundwater cleanup method, which involves pumping groundwater out and purifying it.
- Air sparging: used together with soil vapor extraction; air is injected into the ground below the water table to push contaminant vapors up toward the surface.
- Chemical oxidation: introduction of an oxidant to react with contaminants and break them down into less harmful compounds; a variation of this can be used to treat soil.
- Groundwater circulation wells: water injected with compressed air flows upward in underground wells and contaminants are removed in vapor form along the way.
- Permeable reactive barrier: a trench up to 50 feet deep is filled with material that can react with contaminants or filter them out as groundwater flows through the barrier; in some cases, impermeable side walls are built to funnel water through the reactive barrier.
These techniques are highly technological and expensive, which is further evidence that the contaminants on these sites should be addressed. If they were easy to clean up and not harmful, processes such as chemical oxidation would not be used. Understanding the extreme measures being used to clean up groundwater at brownfield sites, my immediate worry lies in the damaging effects to existing water infrastructure when these properties remain dormant. This is especially concerning when looking at more rural areas, where the economic return of revitalizing these sites may not outweigh the cost and effort required for cleanup.
As someone who is interested in engineering water technology, emerging studies on the use of Vitamin B12 in groundwater remediation and soil compost remediation for immobilizing heavy metals as inexpensive solutions are exciting. In addition, brownfield grants and financial incentive programs for site cleanups are available to assist with redevelopment. The benefits of these investments are clear. For example, a case study on the air and water quality impacts of brownfield redevelopment in five communities shows improved environmental performance at these sites. Although concerns remain about whether damage has already affected the water infrastructure near these properties, green remediation techniques and sustainable approaches to development will better protect water infrastructure, which in turn will result in more favorable outcomes overall, and ensure access to safer drinking water.
Map created by Map Direct, powered by ESRI.
Side by side maps of brownfield areas/sites in New Smyrna Beach (left) and West Palm Beach, Florida (right)