Downstream Floodplain Remediation News
Here is a story that appeared in the Morning Sun on March 3.
“EPA narrows options for Pine River cleanup: Recommended process could cost up to $6.7 million,” Greg Nelson, The Morning Sun, March 3. 2022
For the past few years the U.S. Environmental Protection Agency has been conducting remedial investigations on two sections of the Pine River downstream from the St. Louis municipal dam. A feasibility study done by EPA contractor CH2M on a portion of the river the agency refers to as Operable Unit 3 has been completed.
“The report evaluates the options to clean up the sediment, floodplains and bank soils from the St. Louis dam to approximately one-and-a half miles downstream,” EPA Community Involvement Coordinator Diane Russell stated in a press release. “Areas that show unacceptable risk within OU3 include four floodplains and streambank soils.”
There was, however, only a limited amount of sediment identified within that section as needing remediation, she added. DDT and PBB, which were once manufactured at the former Velsicol Chemical Co. plant in St. Louis, are the primary contaminants found.
The report offers three potential alternatives: Take no action, containment of the site contaminants or excavation and off-site disposal of the contaminated soils and sediment.
In its summary CH2M recommends the EPA choose the removal of the contaminated soil and to backfill and stabilize the floodplain and riverbank.
That would also require additional data collection, obtaining property access agreements from landowners to gain access to the river, and a topographic survey, among others. The cleanup remedy recommended in the report is estimated to cost about $6.7 million to implement.
“The final cost of the project will depend on numerous factors, including actual labor and material costs, competitive market conditions, implementation schedule and field condition,” the report stated. “As a result, the final project costs will vary from the estimate presented herein.”
The EPA expects to release its proposed plan for OU3 sometime this spring. At that time public comments will be accepted on the method selected. “EPA will choose the final remedy using nine criteria described in the Superfund law, which also includes evaluating public comments,” Russell said.
Further downstream in Operable Unit 4, where the Pine and Chippewa rivers converge, an additional investigation is taking place. Russell noted that a future cleanup remedy on that portion of the river will not be made until the study is complete.