Five years after days of steady rain caused the failure of one dam and damaged three others in Gladwin and Midland counties, Michigan, a $400 million project to "repair, improve and restore" the dams are on schedule and on budget.
Four Lakes Task Force photo
Crews with Spence Brothers are currently at work restoring spillways on the Edenville Dam, the largest of the four that also includes the Sanford, Secord and Smallwood Dams. Located on the Tittabawassee and Tobacco Rivers, the Edenville Dam provides water control for the Wixom Lake on which about 2,785 homeowners enjoy waterfront property.
"We had what is basically a big trencher come in," said Jim McIntyre, Edenville project manager, Four Lakes Task Force. "In one pass as it's pulling out the dirt, it puts bentonite concrete with the soil and water back into it to create a wall. That's a pretty unique situation in Edenville because we've got an embankment that's close to a mile long. So that specialized trencher was the most effective way to put in the new I wall, as opposed to driving sheet pile."
To date, crews have demolished the Edenville powerhouse and installed cofferdams at the Tittabawassee River. Fisher Contracting has the contract for the earth work and assisting Spence Brothers with the construction management. Fisher crews also have done the dirt work to build up the Tobacco auxiliary spillway in preparation for building the embankment, followed by the spillway.
They've done a significant amount of the backfill ... it's basically a hill that they're building out of stone, said Shane Willis, Spence Brothers project director. "Then, on top of that, Spence Brothers will be placing concrete to protect that stone so that it can't wash out in a flood. Soil anchors have been installed at the downstream side of that."
The main challenges on the Edenville Dam stem from its size, as well as the Tobacco River, Willis said. Within the 1-mi. length of the dam are three primary work areas.
Four Lakes Task Force photo
"It's a lot to manage from the perspective of our superintendent and quality control manager," Willis said. "It definitely has its challenges, just making sure that you're keeping tabs, because at one point we're going to have significant work activities happening at all three of those spillways."
The second major challenge comes from the fact that there is no place to redirect the Tobacco River which means the river will continue flowing through the existing spillway even as crews rebuild it. Significant coffer damming has to be put in place to keep our work area and our workers safe — and mostly dry — while the river is literally flowing right on the other side of the cofferdam," Willis said.
The includes concrete demolition, earthwork and custom concrete work, followed by the installation of gates, structural steel and the ancillary parts that allow the spillways to function, Willis said.
McIntyre said that crews can only work on about half the spillway at any given time. "The coffers dam it off and create a dry space and you do your work. Then, when that's complete, you flip it over and work on the other side with new cofferdams. Those are pretty significant. On the upper dams, you're talking 15, 20, 25 feet of water that you're holding back and working behind."
Spence Brothers photo
Equipment Mobilization On Edenville Dam
• SCB (soil-cement-bentonite) wall installation equipment: one MT2000 trencher (2,000 hp, 220,000 lbs.) and one MT 3500 trencher (3,500 hp, 400,000 lbs.)
• three Caterpillar excavators
• one skid steer
• boom lifts
• cement and bentonite trucks
• pumps, piping
• 20 semi-load delivery trucks
The Four Lakes Task Force received a $9.8 million grant from the state of Michigan for the restoration project. That is in addition to other state grants including $15 million in 2020 for pre-restoration work and $200 million in 2022. Work on the other three dams continues with each at different stages and scheduled completion dates.
The $90 million Sanford Dam was the first completed, with commissioning of the six crest gates in late 2025. The "most downstream" of the four dams features the largest spillway of the four locations, Willis said.
"What's unique is that instead of traditionally installed concrete, roller compacted concrete was utilized on the auxiliary spillway, and it's the only site out of the four dams using roller compacted concrete."
Four Lakes Task Force photo
Unlike traditional concrete in which concrete is poured into forms, roller compacted concrete is placed and handled more like earthwork, Willis said.
"It's mixed, placed onto an off-road truck, hauled out to the location, dumped directly on the ground and moved with dozers and excavators. And then, immediately, you've got a roller compacting it. It's very similar to a new earthwork operation versus a traditional concrete.
"It's not a new technology in the industry, but for Spence Brothers in particular, and Fisher Contracting, just placing it was a new a new thing for us. It's definitely a unique characteristic of Sanford and it's going well."
Work on the $67.2 million restoration Secord Dam project also has been focused largely on concrete work in recent months. The dam controls water on the Secord Lake and is about 41 mi. upstream of the city of Midland.
"The cofferdams up there are pretty significant from a height perspective," McIntyre said. "You're holding back much more water there, at least from a depth perspective."
Like Secord, the $50.2 million Smallwood Dam project requires significantly high cofferdams. The dam is located on the Tittabawassee River, about 18 mi. northwest of Midland. Crews recently installed the upstream cofferdam and have begun the dewatering process. They are pouring the primary spillway steps and the training wall in bay 2. Other concrete work includes installing soil anchors for the baffle blocks and lower slab of the spillway.
Completion dates on the four dams vary. In addition to Sanford's December completion, Smallwood is scheduled to be finished in June 2026; Secord, September 2026 and Edenville, September 2027. CEG
