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 perchloroethylene (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 spring of 2019, the MPCA continued to conduct sub-slab soil vapor sampling at additional homes and businesses within the area of concern. In the fall of 2019, the MPCA will continue soil vapor sampling in the city of Minneapolis’ right-of-ways in the area. We continue to need access to a few homes and businesses to conduct the necessary activities. The MPCA will be sending access agreement letters to residents and business owners of properties where the agency would like to do this sampling. If you receive one of these letters please contact us as soon as possible so we can complete this very important work.
In the spring of 2019, several new groundwater monitoring wells were also installed in the city of Minneapolis’ right-of-ways near the site. The MPCA will be conducting further investigation of the groundwater in the area. This may include the installation of additional wells for sampling or for monitoring the contamination in the future. These wells may likely be placed within the city of Minneapolis’ right-of-ways, although the MPCA may ask permission to install wells on private property if they are 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