Since more than two decades, remediation efforts of both the U.S Environmental Protection Agency and MichiganDepartment of Environment, Great Lakes and Energy has been focusing on the former Velsicol Chemical Plant site in St. Louis and the adjacent Pine River.
The multi-year, multi-million dollar project to dredge and remove DDT along the river’s north side of the 52 acre parcel was costing more than $100 million. Millions more were spent cleaning up contaminants from the plant and the nearby residential neighborhood.
The EPA and EAGLE have paid more attention to the areas downstream of the St. Louis municipal dam over the past few years.
According to Diane Russell, EPA Community Involvement Coordinator, the agencies are currently working on the third and fourth phases in areas referred as Operable Units 3, and 4.
OU 3 is located approximately one mile downstream of the dam, while OU 4 runs approximately one mile along the point where the Pine-Chippewa rivers meet.
This fall the EPA has been “evaluating options to clean up the sediment, floodplains and riverbank soils in OU 3,” Russell said.
“EPA expects to have a plan, including a public comment period, for a remedy to address Operable Unit 3 contamination next spring,” she added.
The work in OU 4 is unique in that the agencies are using activated charcoal in their ecological study to see if they reduce contaminants such as DDT.
“Additionalstudies are necessary to understand if this technology can be carried forward as a possible remedy,” Russell said.
Researchers from the EPA sampled earthworms from the test site before and after carbon was applied.
Russell noted that the results showed a reduction of DDT in earthworms by approximately 60% after the application of granular activated charcoal.
The location was chosen based on previous remedial investigations, which included the collection of floodplain soils and a small mammal toxicological analysis and food web analysis.
These studies showed that DDT and its metabolites as well as PBB in floodplain soils had adversely affectedecological receptors, including soil invertebrates as well as organisms that feed on the invertebrates.
Other impacts included reduced diversity and biomass, poor reproduction, diminished abundance, and abnormal behavior in robins, shrews, and decreased abundance.
Russell stated that the testing will allow scientists to determine how carbon reduces bioavailability of contaminants for animals. If successful, it could also reduce cleanup costs.
“The study will continue into next year when a determination will be made to either continue or stop the study,” she explained. “EPA and EGLE will also be doing additionalfloodplain sampling to evaluatehow far contamination has traveled downstream within the Pine River.”
These data should be available by February or March 2022.