AYER — Although FMC Corp. no longer owns the property at 9 Bishop Rd., engineer David Rivard-Lentz said the company plans to clean up pesticides and other chemicals that wound up in the soil there over 20 years ago.
Nearby wetlands and the water table beneath the contamination are the areas of concern. The mitigation plan is to excavate the contaminated soil or prevent the spread of contaminants by sealing the soil in place.
The main area of contamination will be injected with clay and cement to solidify the soil and trap the contaminants in place, preventing the further spread of materials into the wetland or water table. This is necessary because, due to the depth of the contamination, the area would most likely have to be excavated otherwise. This area will also have a cover installed to prevent water infiltration.
FMC also plans to have a section of wetlands adjacent to the stabilized area excavated to remove contaminated soil that has spread there. It will then restore the area and re-plant approved plant life.
“Wetlands vegetation will be re-established in the area,” Rivard-Lentz said during the Jan. 25 Conservation Committee meeting.
The excavated materials will be removed to a licensed disposal site, he said.
Commissioners said they’d never seen a slurry of clay and cement injected to trap contaminants before.
Tests are conducted using samples from the site to find the best mix for trapping the contaminants, said Rivard-Lentz. The technology has been used for the past 15 years, he said.
“The data that I have seen is that it has been very successful,” he said.
Several questions, such as which section will be treated first, went unanswered as the decision had been left up to the general contractor.
As mitigation planning progresses, FMC will be able to provide more details, said company representative Michael Shannon.
Concerned about future site owners, commission Chairman William Daniels said that while large corporations have safety measures in place to deal with contamination, small companies and individuals don’t.
The details of the contamination will be on the deed, said Rivard-Lentz, but the end responsibility of not disturbing the stabilized soil is the responsibility of future property owners.
Daniels also asked about any remediation plans for contaminants that have already spread from the area.
After completing the immediate mitigation, Rivard-Lentz said FMC intends to put in place a five-year plan to monitor the area and determine what additional measures are needed.
FMC must provide documentation on all of the testing conducted and stabilization technology proposed for the site.
The commission planned a site walk for Feb. 3 at 10 a.m. and continued the hearing until Feb. 22.