Small spills or disposal of the dry cleaning chemical perchloroethylene (PCE) resulted in contamination of the groundwater. Contamination in the groundwater can release vapors that can rise through the soil and seep through basement and foundation cracks into air inside buildings. This is known as “vapor intrusion.” Recent testing of air in the soil from soil borings in the public right of way has resulted in the vapor intrusion assessment area shown on the map below.
The issue: Vapor intrusion
The groundwater contaminated with PCE could release PCE vapor that can rise through the soil and seep through basement and foundation cracks into homes and other buildings, where it could be inhaled by people. This is known as “vapor intrusion.” If vapor intrusion is occurring, it is likely that vapor levels are higher in basements than on upper floors.
If a problem is found at a property, the remedy for the situation is installing a vapor ventilation system, which operates like a radon mitigation system. If a building has a radon mitigation system that was installed by a certified contractor and is functioning properly, it is likely that the problem of PCE vapor in the building’s indoor air is being addressed.
The Minnesota Department of Health (MDH) is working closely with Minnesota Pollution Control Agency (MPCA) and U.S. Environmental Protection Agency (EPA) on this project because exposure to PCE vapor can be a health concern. MDH has a fact sheet about PCE and potential health impacts:
The EPA is doing the testing and mitigation work (to protect people's health) at affected properties within the core EPA testing area (Zone 1 on the map). The MPCA has been testing soil gas from borings in the public right away to further define the vapor area of concern. The MPCA began testing in Zone 2 in Fall of 2016.
Drinking water: No effects
This site does not affect drinking water. The city of Richfield’s municipal water system currently meets all federal and state drinking water requirements.
West 66th St. and Vincent Ave. Area of Concern
Initial investigation and mitigation of 9 residential properties by MCPA Emergency Management Program.
EPA/MPCA held an open house to answer questions at the Richfield Community Center.
June 2015 – Present
|EPA has been testing residences within their core testing area (Zone 1 on the map).|
|July 2015 – Present||MPCA conducted soil gas and groundwater investigation activities throughout the area.|
|September 2016 – Present||MPCA begins testing of residential properties in the expanded testing area (Zone 2 on the map).|
What do I need to do?
- The EPA and the MPCA will be sending out letters requesting access to your property to collect samples. Once you sign the access agreement, the EPA or MPCA will work with you to schedule a time to do this sampling. You will need to be present at the time of sampling.
With the owner’s permission, the EPA or MPCA will sample the air under the building foundation. Sub-slab sampling is the name given to the process of collecting a vapor sample from directly underneath the basement floor through a small hole drilled in the floor, which takes about 45 minutes. The sample results will be provided to you after the sample has been analyzed which could take a month or so. If test results exceed screening levels it may be necessary to test the air inside the property. The EPA sampling work has been ongoing since 2015. The MPCA sampling work has been ongoing since 2016.
Important: If your house lies in the U.S. EPA core testing area (Zone 1, pink area on the map): Contact the U.S. EPA to arrange for sampling of your home: Sonia Vega, U.S. EPA, 630-481-5025 or firstname.lastname@example.org
Important: If your house lies in the expanded MPCA testing area (Zone 2, orange highlighted area on the map): Sign the access agreement form mailed to you and return to MPCA. Work with MPCA to schedule a time to sample your home. You will need to be present at the time of the sampling. If sub-slab screening levels are exceeded, MPCA will coordinate with property owner to install a vapor mitigation system at no cost to the property owner.
What does sampling involve?
With the owner’s permission, we will sample the air under the building foundation. Sub-slab sampling is the name given to the process of collecting a vapor sample from directly underneath the basement floor through a small hole drilled in the floor, which takes about 45 minutes. The sample results will be provided to you after the sample has been analyzed which could take a month or so.
If sampling indicates a potential problem how can it be fixed?
If the sample results indicate elevated PCE vapor levels, the property can be protected by installing a vapor mitigation system. This system is similar to a typical “radon system” commonly installed in homes and buildings in areas where radon is naturally present in the soil. Such systems consist of a hole in the building floor with a sealed pipe that leads to a low-wattage fan in the attic or on the outside of the building. The fan pulls vapors from beneath the floor and discharges them to the atmosphere through a stack on the roof. If levels indicate that mitigation is needed, the MPCA will install this mitigation system in private residences at no cost to the homeowner.