Gaffney Road Areawide Investigation

Site Narrative

Description

Decades of commercial/industrial use and former dry cleaning operations in the area of Gaffney Road, in the City of Fairbanks, has resulted in multiple areas of soil contamination and area-wide groundwater contamination by chlorinated hydrocarbons, primarily tetrachloroethylene (PCE) and its daughter products- trichloroethene (TCE) and dichloroethenes (DCE). Groundwater investigations from 1997 to 1999 used passive soil gas studies, temporary and permanent monitoring wells, and sewer line sampling to delineate what appeared to be two groundwater plumes above regulatory limits originating in the Gaffney Road area and extending downgradient, generally north-northwest. The smaller, eastern plume exceeds 1500 feet while the longer, western plume exceeds 3000 feet in length. DEC is investigating these areas of contamination in an area-wide approach, looking at all possible sources of contaminants. There now appear to be three sources, associated with two historical dry cleaning operations and the sanitary sewer lines in the area. The wooden sewer lines may have received contaminants and subsequently redistributed them to down-gradient areas through failures in the line, regular leakage, or vapor migration across the pipe into the surrounding soil and water.

Public Health and Environmental Concerns

Perchloroethylene, or PCE is a common dry cleaning solvent has contaminated the soil and groundwater. Two contaminated groundwater plumes containing PCE and its breakdown products, TCE and DCE extend from release locations on the eastern and western side of Cushman Street. Although no drinking water wells have been identified within the plume, irrigation and other private wells are known to exist in the area. The Gaffney Road area is provided with drinking water by Golden Heart Utilities, and a City of Fairbanks ordinance requires residences to hook up to public water supply if it is provided by the Utility. In addition to the contaminant movement in the groundwater, PCE is also volatile and can move from the soil and groundwater into the air, possibly traveling into buildings affecting indoor air quality. DEC is currently operating a sub-slab depressurization system to prevent vapor intrusion into affected buildings. DEC is also monitoring the movement and status of the groundwater plume and periodically monitors contaminant vapors in buildings near the plumes.

Current Status

DEC periodically samples approximately 50 groundwater monitoring wells located throughout the plumes. Contaminant concentrations in groundwater are monitored to determine if the plumes are expanding or decreasing in size, and to see how the concentrations of contaminants and breakdown products change over time. The groundwater plumes appear to be stable, safely separated from the water supply wells for City residents.

DEC has conducted multiple surveys of properties overlying the contaminant plumes to see if there are wells still in use that are used for drinking purposes. Several wells in the area are used for cooling water or irrigation, but none have been found that are used for drinking.

In 2010, DEC installed and operated a combined soil vapor extraction (SVE) and sub-slab depressurization (SSD) system to remove PCE from the soil at the largest release area behind Good News Bible and Book Store (GNBBS). The SSD system also removed vapors from beneath the GNBBS building so that they would not migrate into the building. Since its installation, the treatment system has removed a sufficient mass of contamination that, when coupled with natural attenuation processes in the groundwater, the largest plume appears to be stable, and is anticipated to shrink in size over time. This remedial system was modified during 2016 where large rotary blowers were replaced with an indoor radon fan on the SSD system. In 2019, passively operated pressure differential valves were installed on many SVE wells. The SSD system continues to operate as a preventative measure for vapor intrusion into the GNBBS, while the SVE wells remove soil vapors from the surrounding vadose zone. 

DEC has also sampled indoor air and/or soil gas beneath or adjacent to 22 buildings that are closest to the contaminant source areas and have the greatest risk of vapor intrusion.

EPA staff and contractors from RTI and Jacobs recently completed a yearlong study of indoor air quality in seven commercial and institutional buildings located over the Gaffney Road contaminated groundwater plume. The EPA-led team is studying whether volatile organic compounds in the contaminated soil or groundwater are entering buildings. Samples were collected from indoor air in the commercial buildings as well as the soil gas under their foundations, to look for PCE, TCE and naturally occurring radon. The preliminary results suggest that PCE, TCE and/or radon is entering at least four of the seven buildings at detectable concentrations. Those concentrations were in most cases below target levels published by DEC. The concentrations varied significantly over the yearlong study period as is typical for vapor intrusion sites. The individual results have been communicated to the owners/occupants of the buildings. Based on these results, EPA is looking to collect samples from additional residences that are also over or near the Gaffney plume during 2023.

What's Next

DEC will continue to monitor the groundwater in the contaminant plumes, as well as soil gas in locations above the groundwater plumes and adjacent to buildings at risk to vapor intrusion. DEC will also continue to evaluate vapor intrusion into buildings above the groundwater plume.

The EPA, RTI, and Jacobs are developing a new concept called “soil gas safe communities” to quickly identify indoor contaminants of concern that may be entering buildings from contaminated soil gas beneath homes and buildings. The cooperation of residence/building owners and occupants is essential to the success of this new approach. This approach uses real-time radon detectors, provided free to homeowners, to indicate when vapor intrusion into the home is highest, so that samples for volatile organic compounds can be taken at the most important times. The results can then be used to inform health and safety risks at a community scale and identify actions residents can take to improve indoor air quality.

What can you do?

Please contact the DEC project manager at the number listed at the end of this fact sheet to report if you have a well on your property and what you use it for. Please avoid contact with any groundwater from the contaminant plume. Wells used for irrigation can spread contamination and expose people to contamination through volatilization. Please do not disturb any sampling activities occurring in the vicinity. Some soil gas sampling occurs over a period of several days so the sampling equipment may be left unattended.

The EPA led team of the Soil Gas Safe Community project is seeking more volunteer homes in a specific area shown here: https://soilgassafe.rti.org/.  The project team can be contacted at soilgassafe@rti.org. 

More Information

If you have any questions concerning this contaminated site, please contact Mr. James Fish at 907-451-2117 or at james.fish@alaska.gov. For questions regarding human health, please contact (907) 269-8016 or stacey.cooper@alaska.gov.

Information on PCE, TCE, and other contaminant health effects can be found at the Agency for Toxic Substances and Disease Registry website

Contact the Soil Gas Safe Community Project at soilgassafe@rti.org.

Vapor Intrusion Information:

• DEC vapor intrusion page
• EPA vapor intrusion page