After its decades-long slumber within the banks of the Kalamazoo River, PCB contaminated sediment is being rolled out of bed by an excavator. It’s in for quite a ride over the next two years.
A $25 million project to excavate 120,000 cubic yards of contaminated soil is underway, supervised by the U.S. Environmental Protection Agency and paid for by the paper companies that have inherited the liability for the pollution.
It began Tuesday, Sept. 13. EPA’s on-scene coordinator Paul Ruesch said he hopes crews can complete Phase 1 by the time winter stops the work—that would be the south bank of the river between approximately 21st Street (near Pine Creek Dam) and where the river crosses beneath M-89.
By the time the project wraps up in spring 2018, the banks and some of the riverbed along a 1.7-mile stretch of the river—starting at the Otsego Township dam and headed upstream—will have been stripped of contaminated sediment and painstakingly rebuilt.
How it’s done
PCB, a carcinogenic byproduct of the paper-making manufacturing process that was dumped into the river, is found in varying concentrations throughout the riverbank. After a section of the riverbank is isolated—industrial-sized sandbags create a kind of coffer dam and the water is pumped out—an industrial excavator scoops up the riverbank and surrounding soils.
It’s computer-assisted work, designed to remove only soil identified in a survey backed by detailed sampling earlier in the summer.
“In this (first section of work), the majority of the contamination from all of our modeling and all our sampling shows it’s right on edge sediments and in the banks.
That said, there’s digging of contamination of the bank, but there is also digging to get down to the depth for restoration.”
By that, he means the bank will be reconstructed to withstand erosion.
The sediment is loaded into small dump trucks on treads, which trundle along a narrow, temporary gravel road parallel with the river and bring it to a dewatering area in this phase’s forward staging area along Jefferson Road. More staging areas will be built as crews work different sections of the riverbank.
The spot where it’s dumped is lined and is designed to collect any water runoff and withstand a 25-year rain event. When enough earth is piled up, the excavated soil is hauled away by truck.
“99 percent is going to Coopersville,” Ruesch said, referring to the Republic Services-operated Ottawa Farms Landfill.
Only sediment that exceeds 50 parts per million is hauled in lined trucks to an EPA landfill, US Ecology in Belleville, that is sealed off below ground to prevent contamination from spreading into the water supply.
“That said, as we get in the ground, we may find more,” he said.
PCB is generally only problematic for people, Ruesch said, when it works its way up the food chain and concentrates in fish. Fish advisory signs posted throughout the Kalamazoo River warn against eating fish caught in the river.
That process starts when the riverbank erodes, releasing the PCBs into the river. Layers of paper waste are visible as grey bands in the riverbank. Even that soil, however, is still low in PCB concentrations.
“The stuff you’re seeing on the banks, here, is low concentration. What you see versus what is measured looks a lot worse than what it actually is.”
The remaining steps involve filtering the water pumped from the work area and the excavated soil (plus the rain water that filters through that soil). It is pumped to a treatment center. A series of 20,000-gallon tanks allow solids to settle out. From there it’s pumped through bag filters then through a sand filter and finally through a granulated activated carbon filter.
From there, it is stored in a series of 18,000 tanks and the work site uses it for most of its needs, including heavy use to spray down the site to keep dust to a minimum.
“It’s sampled every day to make sure it meets standards,” Ruesch said. If there’s too much to store, it will be discharged into the river.
Testing
Testing is frequent on the site at really every step. Ruesch said samples are taken after the soil is excavated to verify that the concentrations do not exceed 5 parts per million in the riverbank. It’s tested by two separate labs with a 24-hour turnaround.
The water is tested at its various stages of treatment to keep it to no more than 1 part per billion.
Turbidity in the river is tested at two points downriver to ensure the work is not churning up too much sediment into the water. Devices down the block from the staging area in either direction test dust concentration; real-time feeds let the worksite know when too much dust is being kicked up near local residences.
Reconstruction
Sean Kane, a contractor with the Superfund Technical Assessment and Response Team, explained that the banks of the river will be rebuilt to withstand normal erosion.
That includes a 3:1 grade, rock at some points and at others, something called “root wad”—that’s essentially the roots of a tree plus approximately 8 feet of trunk.
“They’re going to be used for bank stabilization and also as habitat,” Kane said. “They’re going to be keyed and tied in to keep banks from eroding too fast. There’s a biologist who comes in and basically determines, I want this to be built like this; this bank will be built like this.”
Ruesch said it’s perfect for heron, fish, turtles and others.
“It’s actually going to be better than what was there,” he said. In many cases, he said he is working with nearby residents to maintain what was there as much as possible. In one case, that means removing and replacing logs one resident placed near the bank to provide a spot for turtles to sun themselves.
Contact Ryan Lewis at rmlewis@allegannews.com or (269) 673-5534.
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