The Corps of Engineers is preparing a solicitation for emergency repair work at Allegheny River Lock and Dam No. 6, where severe erosion threatens to undermine the dam’s stability.
The erosion, or scour, was discovered during a periodic inspection of the lock and dam near Clinton, Pa., one of eight navigation facilities on the Allegheny River.
The Corps said Oct. 28 that failure of Allegheny Lock and Dam No. 6 could seriously affect the region, with loss of the pool shutting down commercial and recreational navigation until the dam was repaired or replaced.
Additionally, the Corps said dam failure could inflict severe damage on the 8.56-MW Allegheny Lock &Dam No. 6 hydro plant (No. 3494), operated at the project by Allegheny No. 6 Hydro Partners, an affiliate of Sithe Energies Inc.
The Corps expressed concern that ice collecting at the dam or large chunks of ice slamming into the dam could cause it to fail. High river flows also could threaten stability.
Therefore, the government said it is taking immediate actions before winter to minimize the risk of dam failure. Measures include around-the-clock staffing, hourly gauge checks, and coordination of local emergency and water management.
Corps Pittsburgh District officials stressed the situation poses no immediate threat to public safety. However, the district engineer said Corps actions would address what he called the high risk of the dam’s failure. The Corps expects the facility will be operated safely until a permanent fix is put into place, sometime before severe winter weather arrives.
The Pittsburgh District said it is using remotely operated vehicles to inspect other Allegheny River navigation facilities. A Corps assessment determined all eight Allegheny River navigation facilities require critical repairs, as do several on the Ohio and Monongahela rivers.