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Description
Decades of commercial/industrial use 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 and the dichloroethenes. 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 areawide approach, looking at all possible sources of contaminants. There now appear to be three potential 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 distributed them to downstream 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
A rough estimate of the area where groundwater contamination has spread, likely from at least one former dry cleaner. Concentrations of PCE over 200 times the state standard have been found in groundwater in the small area of darker orange. In the lighter orange and yellow areas, groundwater concentrations are much more reduced, but above state standards.
Vapors from this contamination have affected indoor air in two businesses in the dark orange area. We think that the cause of the vapor intrusion is more likely from sewer system leaks or an undiscovered area of high contamination, as opposed to coming from the groundwater in general. We’re continuing to check these assumptions.
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The western plume's groundwater contamination has migrated over time towards the Golden Heart Utility (GHU) wells that supply water to city residents. Results of groundwater monitoring every year since 2001 indicate a stable plume that does not reach the wells. According to results of a DEC well search, there are a small number of private wells in the area, but none are used for drinking water. Evidence to date indicates possible natural degradation of PCE and its breakdown compounds are occurring in the groundwater, since concentrations decrease from the Gaffney Road area toward the GHU wells. The highest concentrations were found in the western plume near Gaffney Road.
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. In order to assess the possibility of this vapor intrusion pathway, DEC conducted air sampling at several businesses located above the highest concentrations of the western plume. Initial sampling in 2002 did not indicate an indoor air problem, however more refined and detailed sampling in 2006 and 2007 has shown vapor intrusion at levels of concern in two of the three buildings sampled.
Current Status
The groundwater plumes appear to be stable, safely separated from the water wells for City residents. Results of the indoor air sampling, however, indicate the need for additional investigation. In August and September of 2007, DEC will resample the soil gas and indoor air at the three original businesses as well as sample at several additional locations on the north side of Gaffney Road. This work will occur in concert with further delineation of the soil and groundwater contamination near the sanitary sewer line along Airport Way and Turner Street.
More Information
- See our vapor intrusion web page
- Fact sheet: "Vapor Intrusion, Gaffney Road Area" June 2007 (PDF 478K)
- Fact sheet: "Vapor Intrusion Sampling Information," ADEC, December 2007 (PDF 254K)
- Final Report on vapor intrusion, Vapor Intrusion Assessment, Gaffney Road Area, Fairbanks Alaska (PDF 144K), Prepared for DEC by OASIS Environmental, Inc., May 2007. Referenced tables and figures are available upon request.
- Map from the 2007 Groundwater Assessment: Map of monitoring wells, with October 2006 sampling results, (PDF 558K) (Trichloroethene=TCE and tetrachloroethene = PCE). Source: OASIS groundwater report.
- Site Summary (PDF 15K), December 1999
- Fact Sheet (PDF 106K), August 1999
- Related fact sheet: Introduction to Groundwater (PDF 412K)
The map below indicates an approximation and conceptual
representation of the contaminated groundwater plumes in 2004.
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