The Arcade and Hawthorne site in St. Paul is comprised of two adjacent parcels in an area of mixed commercial and residential properties. The site is near the intersection of Arcade Street and Hawthorne Avenue East. It is generally bounded to the north by Orange Avenue East, to the west by Arcade Street, to the south by Maryland Avenue East, and extends roughly ½ block to the east of Arcade Street. Formerly occupied by both a dry cleaner and an auto service station, the site was referred to the MPCA in 2011 when contamination was detected by a potential purchaser of the property. The MPCA's Voluntary Investigation and Cleanup (VIC) program identified chlorinated solvent contamination above regulatory limits in soil and groundwater at the site.
This site has been added to the MPCA's State Superfund Permanent List of Priorities (PLP). This means that the agency has access to additional funding to perform work at the site.
What's the problem?
In 2012, an MPCA investigation discovered soil contamination in the area of the former dry cleaner. Sampling also confirmed that groundwater and soil vapor contamination had migrated off the site.
In 2013, the extent of contamination on the site was found to pose a greater risk of vapor intrusion to the surrounding homes and businesses than previously thought. Soil vapor sampling revealed perchloroethlyene (PCE) in concentrations of up to 1,460,000 µg/m3, well above the residential regulatory limit of 2 µg/m3. The new area of vapor intrusion concern includes three additional businesses, an apartment building, and three homes. A neighboring business to the south has potential vapor intrusion impacts that are being addressed. Further investigation will determine if homes and businesses in the expanded area of concern are at risk for vapor intrusion and further define the extent of groundwater contamination.
Possible health effects
Vapor intrusion occurs when chemical vapors seep from contaminated groundwater through the soil and into buildings. The vapors can degrade indoor air, sometimes to the point of affecting human health. Recent research shows that volatile organic compounds (VOCs) entering homes as vapor may be more harmful than previously thought. As a result, the MDH has recommended lowered intrusion screening values (ISVs) for several VOCs, including PCE. Long-term inhalation exposure to PCE may cause symptoms such as impaired cognitive performance and adverse effects to the kidney, liver and immune system. Sensitive populations including pregnant women, infants and young children, elderly people, or those with chronic diseases are most susceptible to these effects.
Site Remediation and Redevelopment Section