Posted on March 2, 2021
COMSTOCK TOWNSHIP, MI — A hydropower company will begin dredging impoundment sludge from a Kalamazoo River side channel on Monday and says it’s planning to expand efforts to remove excessive sediment from a reservoir drawdown to other areas of the river.
Eagle Creek Renewable Energy says it will dredge a small oxbow section of river next to Comstock Township’s Wenke Park starting March 1. The side channel has been filled-in with sediment from Morrow Lake that was allowed to wash downriver last year during a reservoir drawdown.
The company says it plans to remove about 3,000 cubic yards of sediment — a small fraction of the 114,000 cubic yards of impoundment sludge the company estimates is choking the river between Morrow Dam and Cooper Township.
State regulators consider that an underestimate.
Eagle Creek, which announced the information through its subsidiary, STS Hydropower, said the dredging should last until mid-May. An excavator arrived at the park Thursday.
The state gave Eagle Creek a March 1 deadline to begin dredging the oxbow in a Feb. 12 letter instructing the company to also start making plans to excavate other areas.
In a news release, Eagle Creek said it’s “concurrently developing plans for additional sediment removal projects” in consultation with the Michigan Department of Environment, Great Lakes and Energy (EGLE) and the U.S. Environmental Protection Agency, which is overseeing a separate Superfund cleanup downstream this year.
Eagle Creek licensing and compliance David Fox told the Kalamazoo River Superfund Citizen Advisory Group (CAG) on Thursday that the company has developed a short list of additional areas its eyeing for dredging and it would be showing that to state regulators next week.
“I think that the best analogy here is we’re trying to peel an onion,” Fox told the citizen group, describing Eagle Creek’s efforts to investigate the downstream sedimentation.
“Because of the answers that we have, we’re able to start simultaneously working on removal projects,” said Brian Mastin, an AECOM consultant working for Eagle Creek.
Bathymetric surveys and core sampling found sediment deposits more than an acre in size, ranging from two to 10 feet thick in some areas downstream of Eagle Creek’s Morrow Dam in Comstock Township. Investigation maps show deposits more than 9-feet thick near downtown Kalamazoo and more than 11 feet thick next to the city wastewater plant.
One deposit stretches nearly 2,500 feet from the wastewater plant to Mosel Avenue, measuring about 136,700 square feet in size with about 14,300 cubic yards of mud.
Deposits nearly 4-foot thick were found at the border between Parchment and Cooper Township, the furthest downstream that sediment totals were surveyed.
Biologists and state natural resources officials say the sediment has smothered wildlife habitat and likely caused long-term harm to the river’s fish and mussel population.
The impoundment sediment began flowing through the dam in November 2019 after Eagle Creek unexpectedly drew the reservoir down for an “emergency” spillway gate repair project that the company did not begin installing until December 2020.
Eagle Creek restricted river flow volumes four times last fall while it replaced the gates. The 1,000-acre Morrow Lake reservoir has since been refilled.
A November 2019 photo from the Kalamazoo County Sheriff’s Office shows a 1967 Chevrolet Impala found buried in the Morrow Lake mud after the reservoir was drained by Eagle Creek Renewable Energy.
The company hopes the oxbow near Wenke Park can trap additional upstream sediment once it’s been cleared — although the bulk of Morrow sludge has likely deposited further downstream already.
Kenneth Kornheiser, vice president of the Kalamazoo River Watershed Council, thinks Eagle Creek of focusing on the oxbow because it offers ready access.
“To go into the river, they need a place they can get to it,” Kornheiser said. “This is a place they can get to the sediment easily. You’ve got public land they can use. They are not having to gain easements on people’s property or create a road to pull heavy equipment across.”
Advocacy groups like watershed council and the Kalamazoo River Alliance have been pushing Eagle Creek to remove the sediment before river flows increase with a spring thaw and move it further downstream into areas around Plainwell, Otsego and Allegan.
“When that occurs, some of the sediment is going to be washed downstream,” Kornheiser said. “We don’t know where it will go, how much of it will go. That’s a big concern.”
“Where those sediments are now may not be where they are going to be in six months,” he said.
Dredging work plans filed with state regulators show that Eagle Creek plans to cut river flow into the oxbow with a sheet-pile wall at Wenke Park and truck the dried sediment to a secondary staging area near the dam next to the decommissioned coal fired power plant.
Map showing plans by Eagle Creek Renewable Energy to dredge Morrow Lake sediment from an oxbow section of the Kalamazoo River in Comstock Township.
Where the dewatered sediment goes from there has not been determined, Fox told the citizen group.
Fox said Eagle Creek is exploring several options such as using the material to shore up dam embankments or create a new permanent landfill at the dam. The company is exploring “beneficial re-use opportunities” for the material.
“I’m hoping within the next couple months we’ll have a much better idea where we can put this,” Fox said, adding that reducing sediment landfilling costs “means I’ll have more ability to remove material from the river.”
