The Bulinski Point Superfund site is located on a peninsula on the south shore of Shagawa Lake west of Ely, Minnesota. It is surrounded by mostly seasonal residences with private wells. Approximately 25 residences are within a quarter-mile radius of the site.
Contamination from suspected chemical dumping has been identified in nearby residential wells used for drinking water and may possibly contribute to additional remediation efforts involving indoor air quality at the affected residences.
What's the problem?
- A site investigation in 2002 detected tetrachloroethene (also known as PCE, or "perc," a solvent used in industrial processes, metal cleaning, dry cleaning, and textile processing) concentrations in groundwater that exceeded the Minnesota Department of Health's Health Risk Limit of 5 micrograms per liter, also stated as μg/L. The source of the contamination was traced to a ditch where it was believed PCE was dumped.
In early 2003, the MPCA installed pairs of granular activated carbon water filtration units at three Bulinski Point residences. Since that time, the MPCA has regularly collected water samples at the three properties. PCE concentrations have ranged from 0 to 125 μg/L, but PCE has never been detected in any of the samples with well water filtration treatment. This indicates that the water filtration systems are effectively removing the contaminants.
In October 2014, soil gas samples were collected from beneath the three residences with the carbon filters to determine whether soil vapors from the contaminated groundwater could be impacting the indoor air. The basement sub-slab samples were analyzed for PCE and other volatile organic compounds; all were detected at concentrations below their respective MPCA Intrusion Screening Values (the amount of a chemical in indoor air that is considered safe for all people to breathe for a lifetime).
Current MPCA site activity
The water supply wells located at affected residences are sampled semi-annually, and the carbon filtration systems are maintained. Vapor intrusion does not appear to represent a health risk at this time in the residences sampled. However, future sampling will be conducted, and the results will be compared with the 2014 sampling results. The MPCA is working with the city of Ely and Morse Township toward a permanent drinking water solution for the affected residents.
- Source area investigation (c-s3-24a)
- Residential Water/GAC system sampling & site data review (c-s3-24b)
- GAC system & soil vapor sampling review (c-s3-24c)
- Water supply alternatives analysis (c-s3-24d)
Sondra Campbell, Hydrogeologist, 651-757-2840