Boardman Dam removal
- LocationTraverse City, Michigan
Methodsdewatering, bypass pumping
Michels removed an earthen dam, restored approximately 2 miles of river channel and flood plain to its native condition, removed a 100-year-old powerhouse and bridge, and constructed and paved a road. The majority of the work was completed in hilly terrain with low flooded flats where channel and flood plain were excavated. In all, 350,000 yards of material was excavated and transported by off-road haul trucks through wet and muddy conditions to new locations along the project route.
Following the lowering of the impounded water, a roughly 1.5-mile-long access road needed to be built through the project to continue working along the river. River route reconstruction included working with the engineer to identify and excavate to the native channel bottom, reconstructing the channel bed by placing a rock bottom made of cobble-size rock and boulders, working with a subcontractor to build log jams and log structures to protect banks from erosion, and assisting a subcontractor with recreation of river bank and flood plain vegetation.
Mobilization was impacted by a one-lane, 10-ton bridge at the laydown yard that was later demolished and replaced with a 450-foot, two-lane road. Controlled dewatering impacted the rate at which the channel could be excavated.
To remove the dam, Michels built a siphon system to dewater the impound before orchestrating the controlled breach of the dam through a constructed spillway. The siphon system consisted of 14 30” HDPE pipes each spanning 300’ from the flooded impoundment over the earthen dam to the newly constructed river channel. The siphon system is one of the largest to be constructed in North America, dewatering at 180,000 gallons per minute. The spillway consisted of articulated concrete block mats to reinforce the channel.
The community was heavily involved with this project through its Implementation Team, which consisted of the Grand Traverse band of Ottawa and Chippewa Indians, Grand Traverse County, Conservation Resource Alliance, DNR, DEQ and EPA. Michels assisted on site with fish rescue during the dewatering process.
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