The Corps of Engineers has awarded a $2.97 million contract to Brayman Construction Corp. to repair a severe erosion problem that threatens to undermine the stability of Allegheny River Lock and Dam No. 6 in Pennsylvania.
Brayman Construction, Saxonburg, Pa., is expected to begin repairs the third week of November, the Corps said Nov. 13. The repair plan addresses a scoured area beneath the dam and calls for the company to install a steel sheet pile wall, fill the void with grout, and place erosion control material along the dam’s downstream toe. (HNN 10/29/08)
The Corps said work should be completed quickly, before the end of December. It expressed concern that ice collecting at the dam or large chunks of ice slamming into the dam in its present condition could cause it to fail. High river flow also could threaten stability of the structure.
The Corps plans to conduct a public meeting in Kittanning, Pa., Nov. 18 to provide more information on the repair work. Corps officials will make a presentation at the meeting, followed by a question-and-answer session.
Corps Pittsburgh District officials stress there is no immediate threat to public safety. However, the Corps added that failure of the dam could seriously affect the region, with loss of the pool shutting down commercial and recreational navigation until the dam was repaired or replaced. Additionally, dam failure could inflict severe damage to 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.
Allegheny River Lock and Dam No. 6 currently is operational. The district has implemented measures to ensure the risk of failure is minimized and the facility is operated safely until repairs are completed. The procedures include around-the-clock staffing, hourly gauge checks, and coordination of local emergency and water management.
The erosion 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 all eight of the facilities require critical repairs, as do several on the Ohio and Monongahela rivers.