By the end of this month, the Minnesota Pollution Control Agency (MPCA) should have a contractor selected to complete the clean up project at the Washington County Landfill in Lake Elmo.
Doug Day, MPCA supervisor of the closed landfill unit, and Jeff Lewis, commissioner of the MPCA, shared the contractor selection process with the Lake Elmo City Council last week. They also provided an update about the “dig and line” method the agency selected to contain perfluorochemicals (PFCs) found in the landfill, located off of Jamaca Avenue near Lake Jane.
Day said the contract was put out for bids on April 30. Peter Tiffany, a MPCA senior engineer and spokesperson, said the lowest initial bid is about $18.5 million, and the state of Minnesota will be paying for the cleanup. 3M will also be providing $8 million in funds.
How the contaminants got there
The PFCs were legally dumped in the landfill by 3M from 1969 to 1975. 3M formerly used the chemicals to make products that resist heat, oil stains, grease and water, such as Scotchgard and Teflon. The byproduct from these inventions was a PFC manufacturing waste that was transported to the landfill until 1975, when a clean soil cap was installed, according to the Minnesota Department of Health’s (MDH) Web site. From 2000 to 2002 3M phased out its use of the PFCs, according to the company’s Web site.
Based on recent testing results, the MDH found some of the waste disposed of at the landfill contained perfluorooctanoic acid (PFOA), according to the departments Web site.
The MDH has proposed a “Health Based Value” for PFOA of seven parts per billion in ground water. Levels of PFOA collected at the landfill ranged from 70 ppb to 1.3 ppb downgradient from the site, according to the MDH. In 2004, samples of residential wells in Lake Elmo showed low levels of PFOA, less than one ppb, in seven wells. In 2006, the MPCA and MDH collected 509 samples from private wells for analysis. As a result, 100 residents were provided with bottled water and advised not to drink their tap water.
‘Dig and line’
The clean-up method selected by the MPCA to contain the PFCs involves digging up the old landfill and installing a state-of-the-art triple liner. The first layer will be 60-millimeters of high density plastic, and on top of that will be a drainage net, Tiffany told the Review last September. That process is repeated to add additional layers.
According to the MPCA, the reason for digging up and lining the landfill is related to soil composition in the area. The officials are unsure if soil analyses were performed in 1969 to determine if the area was non-porous enough to support an industrial landfill. As it turns out, the site is in fact a poor location to house a landfill and PFCs and other pollutants can leach through the non-porous soil, according to the MPCA.
“We will be constructing this landfill in a sequential fashion,” Day said at the council meeting. “By that, I mean, we will begin digging a new, triple-lined cell at the southern most part of the site, and then relocating waste into that cell. The number of cells depends upon the actual waste amounts we have to dig up.”
He added that the MPCA expects the project to be completed by Oct. 31, 2012, or even earlier if the schedule can be moved up.
Due to the smell of the garbage in the landfill, the relocation of the waste will be done primarily in the fall and winter months, Day said. The construction of the liner will the be completed during spring and summer.
In order to minimize odors involved with the clean-up, Day said the MPCA will try to continue to operate the gas collection system on the site as long as possible.
However, Tiffany said gases couldn’t be burned to minimize odors once the landfill is open, but working during the winter months should help.
“People aren’t going to be out as much, and they won’t have their windows open,” Tiffany said.
Water-monitoring at the site will increase during the project because the ground water pump-out system on the site would have to be turned off during the lining process, Day said.
“We’re not anticipating that situation will create problems initially, but we are concerned enough that we want to monitor it more frequently,” he said.
The MPCA also installed an air-monitoring system on the site about two weeks ago.
“It’s (the air-monitoring system) part of a regional setup to monitor PFCs in the air,” Day said. “That has never been done before.”
Day added that the MPCA will take air samples in the before the project, and more once the construction on the landfill begins. He said there is currently no standard for measuring PFC contamination in the air.
Protecting against pollution
Council member Brett Emmons questioned Day about what precautions the MPCA is taking to ensure that PFCs from the landfill don’t leach into surrounding areas.
“We currently have a monitoring system in place; we sample a number of residential wells, and a number of monitoring wells on-site,” Day said in response to Emmons’ inquiry. “We will continue that – in fact, we will increase the frequency of that.”
Day said that the MPCA is also working with the city to set up public meetings to talk about the project.
“There will be a public meeting, we hope at the end of this month, in which we can express more detail about the different aspects of the construction,” he said. “At that time, we’ll have our staff and engineers in attendance to answer questions in detail.”