Photo courtesy of Ohio Department of Natural Resources
The Ohio Department of Natural Resources (ODNR) is overseeing the $24 million undertaking to replace the historic McConnelsville Dam.
In an effort to preserve the historic Muskingum Parkway lock and dam system and allow for continued recreational navigation, crews in Morgan County, Ohio, are replacing the historic McConnelsville Dam. The Ohio Department of Natural Resources (ODNR) is overseeing the $24 million undertaking.
Photo courtesy of Ohio Department of Natural Resources
"There have been several repairs to the sheet pile structure, including interim improvements to stabilize the right abutment," said James Hilovsky, a team lead of ODNR's division of engineering. "Overall, the existing cellular sheet pile dam is in poor condition beyond its serviceable lifespan, and in need of replacement."
Site work and preparation began earlier this year, with water work starting in June. The project is expected to be completed in three summer construction seasons.
"We are currently in the first phase, which includes construction of the left and right abutments and a portion of the new dam starting from the left abutment. The remaining sections of the dam will be constructed in the second season, and the existing dam removal and other site work completed in the third season."
The new structure will be approximately 580 ft. downstream of the existing dam.
"The original dam was constructed in 1841 and was similar in nature to many of the other dams along the river which are rock-filled timber crib structures, later capped with concrete. The original McConnelsville Dam failed in the late 1940s and was replaced with the sheet pile structure currently in service today."
The dams along the Muskingum River are considered critical to maintaining the recreational navigation through the lock system. There also are miles of shoreline, docks, bridges and other infrastructure that rely on the water levels maintained by these dams. "It's crucial to ensure these dams are maintained in a safe condition in order to protect the life and property upstream and downstream of the structures," Hilovsky said.
"As the system approaches 200 years old, it has become a vital part of the identity of the communities that surround it. The system is located in the heart of Appalachian Ohio, and the investments that are being made in the system result in opportunities for construction jobs, material and equipment supply and opportunities for various specialty subcontractors to take part in a historic rehabilitation project."
The dam currently has a sheet pile vertical face. This new design will have a concrete stair step face which will provide a more pleasing look. The design also has the added benefit of improving energy dissipation and reducing the potential for dangerous rollers to form at the toe of the dam.
The Ruhlin Company was selected as the construction manager at risk (CMR). Through the CMR delivery method, Ruhlin has been able to provide early input on design concepts, constructability concerns, cost estimates and scheduling. They also have been able to pre-qualify subcontractors to ensure the most qualified subcontractors are available to complete the work.
Photo courtesy of Ohio Department of Natural Resources
The current dam, constructed in 1841 and reconstructed in 1959, is approximately 14 ft. in height with a 192-ft.-wide principal spillway and a 394-ft.-wide secondary overflow. It is regulated by the ODNR Dam Safety Program as a Class II structure. The replacement dam was designed by Michael Baker International, which is the engineer of record, providing construction administration services for the project.
"The most challenging aspect of this project is working on the Muskingum River," Hilovsky explained. "The project has been phased to occur during the historically lower pool levels, but the river can vary significantly depending on rainfall."
Work is currently under way to construct the drilled shaft abutment walls, starting on the left abutment and moving next to the right abutment. The contractor also is beginning to place concrete for the in-water dam, along with the installation of a sheet pile cutoff wall in the canal embankment.
The rock causeway, abutment cofferdams and initial excavations for the abutments have been completed. A temporary access bridge also was installed across the canal to provide access for the heavy equipment and materials that need to be brought to the site. Tree clearing and other site preparations were completed before construction began in June.
Clearing the east riverbank of the Muskingum River included removing trees and vegetation. Re-grading the canal embankment to create a work platform for the abutment and access to the causeway was also necessary.
The stair stepped dam will be poured in lifts. The first lifts will be placed underwater via tremie. Once the concrete structure is complete, post tension rock anchors will be installed along the crest of the new dam to anchor to the river bedrock.
The existing dam's sheet pile cells will be removed and the sand and gravel inside these cells will be left in place. Cells on the right abutment will remain in place to aid in stabilizing the adjacent roadway embankment. Cells on the left abutment will remain in place and be converted to a fishing pier. The existing dam will be demolished at the end of construction.
Hilovsky said the primary concern when surrounded by water is the safety of the crews working in the river, as well as protection of the work.
"The causeway elevations were carefully selected to balance risk of overtopping and maximize working days during the summer season using historical river elevations. The project also was designed to maintain recreational access through the canal and lock."
Construction of the abutments on each side of the dam allows for the geotechnical subcontractor to complete these scopes of work without mobilizing in subsequent seasons. The permanent improvements are contained within ODNR property; however, the right abutment requires a lane closure on the adjacent road and ongoing maintenance of traffic throughout the project.
Although construction is expected to be completed by the end of 2026, this work is highly dependent on the elements and river water levels.
"Weather is always a factor in dam construction, especially when working in the river," Hilovsky said. "The project has been phased to work during the optimal season based on past history of the river, but the project team maintains a construction monitoring plan to ensure the team is constantly monitoring and able to react to changing weather and water levels."
Photo courtesy of Ohio Department of Natural Resources
The materials being used on the project include concrete, reinforcing steel, graded aggregates and earth-fill. The concrete mix has been designed specifically for this project. Crews will be placing a large quantity of concrete under water via a tremie.
Among the equipment on site is a long-reach excavator.
"This machine has the same configuration as a regular excavator but has a much longer boom and dipper stick to give it a longer reach," said Hilovsky. "We also are using an excavator with a drill attachment. This is a very specialized piece of equipment capable of drilling deep cylindrical shafts in earth and rock. This is essential to construct the soldier pile walls for both abutments."
Hilovsky praised the design and permitting partnership with Ohio EPA, US Army Corps of Engineers, Ohio State Historic Preservation Office and Morgan County, and underscored the effort is a first of its kind in recent ODNR history.
"The Muskingum River Parkway is a unique system that has been in service since the 1840s. This is an incredibly important project to help preserve this system and allow future generations to continue to experience this piece of history." CEG
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