The Trowbridge Dam in Allegan is the target of a years-long project to remove chemicals called polychlorinated biphenyls, or PCBs, from the section of the Kalamazoo River near the dam.
The dam is part of a large EPA Superfund site that stretches along the Kalamazoo River.
At the dam, contaminated sediments are removed by a large dredging vessel that moves around the dam reservoir sucking up sediments.
Brian Kelly, site manager with the EPA, said dredging of the river will be complete in six to eight weeks.
“Right now this dredging is the last of the PCB sediment in this area. So it's going to be a huge milestone in just a few weeks that the PCBs are out of this river in this area," Kelly said.
Once dredged, a mix of water and sediment flows through a mile-long tube to a containment area. The sediment-filled water is routed into large bags that let water seep out while keeping sediments inside.
The water is then treated at an onsite water treatment plant and delivered back to the watershed. The contaminated sediment-filled bags are then transported to specialized landfills for hazardous materials.
Kelly said after PCB dredging is complete, the next step of the project will be preparing to eventually remove the dam by digging a new "pilot channel".
“The purpose of the pilot channel is when the water goes down, we want to guide the river back to its pre-dam 1898 channel," Kelly said.
Workers will also remove PCBs from the river embankments during the construction of the channel.
“This time next year, we're going to see something no one has seen in a hundred years, a free-flowing river," Kelly said.
EPA Region 5 Administrator Ann Vogel said extensive testing and sampling will be conducted once PCB removal is complete and throughout the process to ensure the PCB removal was successful.
"Sample, sample, sample!" Vogel said.
Additionally, Vogel said the river will continue to be monitored by the state of Michigan as part of the state's routine water-quality monitoring programs.
