Tennessee Valley Authority
Bear Creek Dam Rehabilitation
June 2008
Since its completion in 1969, the earthen Bear Creek Dam has experienced foundation leaks. Previous efforts to control leaks have been ineffective over the long term.
Following periods of heavy rainfall, the reservoir level can rise, and increase the risk of dam failure. To reduce this risk, TVA prepared an Environmental Impact statement to evaluate alternatives for a long-term solution. After thorough study, public involvement, and several opportunities to provide comment, TVA signed a Record of Decision on September 10, 2007 stating it would build a roller compacted concrete structure at the downstream toe of the existing dam along with a water cutoff "wall" under the new structure to block water passage under the dam. Site preparation began in September 2007.
Construction Report Update
Safety and Environmental Issues
The Safety and Environmental Performance at Bear Creek has been perfect to date, with no reportable events.
Excavation
Most of the excavation at the project has been completed, except for the some small areas near the sluice outlet structure and along the spillway. These locations require the embedding of H beams into the rock to hold back the soil. The construction of these soldier pile walls will begin this month. Once completed, the soldier pile walls will allow excavation of the remaining areas. Dental grout installation at the south end of Phase 3 is nearing completion.
Even with the recent heavy rains and increase in the water level of the reservoir, the dewatering system successfully kept water out of the excavation.
Grouting
Final closure and verification of the grout curtain in the spillway and the south embankment dam will be completed this week. Drilling and grout operations will move to Phase 3, which is the deepest section of the excavation. The problem areas found in Phase 1 near the spillway will be injected with a low mobility grout.
Current Activities
- Most of the project excavation is complete, except for small areas near the sluice structure and spillway.
- Installation of soldier pile walls near the sluice and spillway structures.
- Final dental grout at the south end of Phase 3.
- Final verification of spillway and left embankment grouting operations.
- Drilling and grouting will begin in Phase 3.
View of the grouting operations in the spillway section.
