The 55th and Lyndale Avenue South vapor site in Minneapolis is comprised of two adjacent properties that included a former dry-cleaning operation. The site was referred to Minnesota Pollution Control Agency (MPCA) in 1999 by a property owner working on a property transfer.
The nearby investigation of a petroleum release in 2010, revealed perchloroethlyene (PCE, also called tetrachloroethene) in groundwater and soil vapor near the original site. It is likely that the contamination may be coming from more than one property.
What's the problem?
In 2012, an MPCA investigation looked for sources of PCE contamination and tested for underground soil vapor. The investigation identified the former dry-cleaning site, and work began to start defining the area of contamination.
The soil vapor investigation continued in 2013 and 2014, and revealed the possibility of vapor intrusion at several nearby homes and businesses. Vapor intrusion occurs when vapors from chemicals in groundwater migrate up through the soil and into buildings through cracks or other pathways in the building's foundation. The chemicals can then contaminate indoor air.
A mitigation system was installed in the office area of a nearby commercial building in 2014 in response to soil vapors exceeding 100 times the industrial indoor air standard underneath the building. Since then, the MPCA has installed vapor intrusion mitigation systems in 11 homes, and several commercial buildings have been mitigated by their owners.
In the fall of 2018 and continuing in 2019, the MPCA would like to conduct sub-slab vapor sampling at several additional homes and businesses within the area of concern. The MPCA will be sending access agreement letters to residents and business owners of properties where the agency would like to do this sampling.
The MPCA will also be conducting further investigation of the groundwater in the area. This may include the installation of wells for sampling or for monitoring the contamination in the future. These wells are typically placed within the city of Minneapolis’ right of way, although we may ask permission to install these wells on private property if it is needed.
When chemical vapors enter buildings through the foundation, the amount in indoor air is usually not high enough to affect most people’s health. The possible health effects from breathing PCE depends on the amount in indoor air and how long people breathe it.
Long-term exposures to PCE may increase the risk of certain types of cancer based on studies in workers or animals breathing very high levels of these contaminants (thousands of times greater than what may be found at vapor intrusion sites). At high levels in the workplace, PCE can also cause neurological effects such as vision changes or delayed reaction time.
For more information regarding health and vapor intrusion please go to the Minnesota Department of Health website.
Minn. Department of Health
651-201-4897 or 800-657-3908