The Environmental Protection Agency (EPA) is securing federal dollars to install a system to remove contamination in one occupied building.
The other building is currently unoccupied.
These results are part of an ongoing EPA study of an underground plume of tetrachloroethene (PCE) in downtown Le Mars, northwest of the Central Avenue/Plymouth Street intersection.
The study began in 2011.
Now the EPA is planning a public meeting at 7 p.m. Tuesday, Dec. 10 at the Le Mars City Hall to explain more about the EPA's investigation.
"I've talked to several property owners in town and they're concerned about what's going on. They have a lot of questions," said Susan Fischer, the EPA's on-scene coordinator. "We're going to do a public meeting to kind of help everybody to understand what PCE is and why we are there investigating it."
PCE is a man-made chemical that can cause cancer if ingested and possibly through inhalation, according to information from the EPA.
EPA study found a plume of PCE mainly stretching about 1 1/2 blocks north and about three or four blocks west of the Plymouth/Central intersection.
EPA experts earlier noted they are not concerned with anyone in Le Mars ingesting the chemical in contaminated groundwater at this time.
The city's drinking water is not contaminated, EPA officials said.
"The main thing we're dealing with right now is vapor intrusion issues," Fischer said.
That means PCE vapor is rising into buildings into the air people breathe.
"Vapor intrusion is like radon," Fischer said. "The PCE is in the groundwater. It vaporizes off the groundwater and it comes up the path of least resistance, usually into cracks of foundations in basements."
For more than 1 1/2 years, the EPA has been taking air samples inside buildings in the plume area.
Based on results so far, EPA officials want to install mitigation systems in the two buildings with high levels of contamination, Fischer said.
A mitigation system would help remove PCE contamination from the indoor air of those buildings.
The EPA has access to $180,000 in federal dollars for this project, Fischer said.
The federal dollars will pay to install the mitigation system and the EPA will maintain it throughout its about 5-year warranty, Fischer said.
The owner of building is asked to pay for the electricity to run the system.
After the warranty is up, the EPA turns the system over to the property owner's responsibility.
The EPA plans to install the system in the occupied building during the second week of December, Fischer said.
Plans are not set for when to install a system in the unoccupied building.
The names of the privately-owned buildings are not public information, Fischer said.
PCE air contamination is not an issue in outdoor areas, she added.
Officials say they don't know how long the PCE vapor intrusion problem will last.
"It depends on further investigation finds and what else we can do to mitigate to the PCE plume," Fischer said.
The source of the contamination has not been identified, she said.
"We're working on trying to discover the source area," she added.
PCEs are in many different commercial chemicals, ranging from those used to clean and polish metal to dry cleaning fluid.
A large number of industries use this type of chemical, according to information from the EPA.
Ultimately, the EPA could choose to remove as much of the ground contamination as possible.
"We haven't made decisions about that yet," Fischer said. "We're not done with the investigation yet. It's always a possibility but it depends on what we actually find."
The EPA investigation of the plume and contamination in Le Mars is ongoing, Fischer said.
"We're still doing vapor intrusion investigation of other buildings," she said.
During the second week in December, the EPA will continue taking indoor air samples in building basements.
These samples, along with ground water and soil samples, help the EPA track the size of the plume.
There is no definite completion date of the study, Fischer said.
Testing can show higher readings at different times of year, she explained.
"We may have to do several rounds of sampling, based on winter versus summer, when the house is closed up or when the air conditioner is on versus the heater," she said. "We may have to come back into these buildings and take more samples."