A recently released project outline from the U.S. Army Corps of Engineers provides a detailed look at what’s planned for Phase 2 of the Rough River Dam Safety Modification project.
The document outlines how the next phase of construction is expected to be carried out, including what will be built, how it will be constructed, and the scope of work required for contractors bidding on the project.
What the Project Plan Confirms
According to the official project outline, Phase 2 will involve a major rebuild of key components of the dam’s outlet system.
This includes:
- Construction of a new control tower
- A new outlet tunnel
- A new stilling basin to slow water before it enters the tailwaters
- A new outlet channel
These new components will be built on the left side of the dam.
Once the new system is fully operational, the existing control tower and tunnel will be permanently sealed and filled with concrete.
The Cutoff Wall: The Long-Term Fix
One of the most significant parts of the project is the construction of a deep underground concrete cutoff wall.
According to the project outline:
- The wall will extend approximately 1,600+ feet across the dam
- It will reach depths of up to 200 feet into the foundation
This wall is designed to stop water from moving beneath the dam through the underlying karst geology, which has been the source of seepage concerns.
Why This Work Is Necessary
The dam is built on karst terrain, which can develop cracks and voids over time.
This type of geology allows water to move underground, which is what led to the long-term seepage issues being addressed through this project.
The cutoff wall and new outlet system are designed to provide a long-term solution to those concerns.
Additional Construction Details
The project outline also includes several other major components:
- A new approach channel leading to the outlet system
- A service bridge connecting to the control tower
- A large temporary coffer dam to allow construction in a dry work area
- Grouting and stabilization work within the dam foundation
Once construction is complete, Kentucky Route 79 is expected to be relocated back across the top of the dam.
Project Timeline and Cost Range
At the time of the project outline:
- Estimated construction duration was approximately 2,190 days (about 6 years)
- Estimated project cost range was between $250 million and $500 million
More recent updates have since placed total project costs higher as the project has progressed and been refined.
Lake Levels During Construction
One of the most common concerns is whether lake levels will be lowered further.
Based on public statements from the Corps during earlier project discussions, the expectation has been that the lake would remain at a summer pool of approximately 490 feet during construction, though levels are evaluated periodically.
At the time of this project outline, no additional reductions were specified.
What This Means for Rough River Lake
This project outline provides a clear picture of the scale and complexity of the work planned for Phase 2.
The combination of a new outlet system and deep cutoff wall represents a long-term investment in stabilizing the dam and reducing risk.
For lake users and property owners, the key takeaway is that the work is designed to address the underlying issue while allowing the lake to continue operating during construction.
Sources
- SAM.gov Project Listing – Rough River Dam Safety Modification Phase 2
- U.S. Army Corps of Engineers