Pittsburgh District Expedites Channel Opening
The Pittsburgh Engineer District is moving up creation of a 100-foot navigable channel through the former dam on the Lower Monongahela River at Elizabeth, Pa.
While the channel through the dam at the former Monongahela Locks & Dam 3 site was expected to be opened in December, the project’s expedited date is August 28. That became necessary after a miscalculation in anticipated water depth over the lock sills led to a 7-foot depth restriction through the landside lock, through which all navigation traffic is flowing.
The dam at the site was breached with controlled explosives July 10 as part of a project to create a continuous pool of riverway stretching 30 miles from Charleroi to Braddock, Penn., improving navigation on the Lower Monongahela River.
“When making outflow adjustments to the dam at Braddock Locks and Dam to equalize the pools, the Corps discovered a discrepancy in the lock upper sill’s clearance height and river levels based on available historical data,” said Alan Nogi, the district’s operations project manager for the locks and dams branch. “The Corps’ lock system uses NAVD 29 elevation measurements, while the USGS uses NAVD 88, which offers different markers for elevation. As a result, the data shown on the navigation charts and as-built drawings for the 117-year-old lock of the upper sill elevation was 1 foot lower than actual conditions. In response, the Corps enforced a 7-foot draft restriction to ensure safe clearance over the upper sills during the dam’s demolition process.”
After raising the pool elevation to facilitate demolition at the dam, Locks and Dam 3 staff discovered a discrepancy July 15 between the actual water levels over the upper sills compared to those anticipated on the navigational chart. That led to the district implementing the 7-foot draft restriction per Navigation Notice 207476.
“Although the lock remains in service, the district recognizes the restriction’s impacts on industry,” the district said in a news release. “The district is working with its contractor to open the navigation channel through the existing fixed-crest dam, eliminating the need to use the locks.”
Joseph B. Fay Company of Pittsburgh, Pa., has the contract for the dam removal. The contractor is adjusting its work schedule to prioritize the channel opening, Nogi said.
“We are committed to opening the 100-foot-wide channel through the dam for commercial navigations as safely and expeditiously as possible.” said Col. Nicholas Melin, commander of the Pittsburgh District.
Nogi said the Pittsburgh District has not seen any significant change in traffic flow, nor a queue that would indicate an increased delay to navigation at the site.
Once the navigation channel is opened, industry and recreational traffic will no longer have to pass through the lock. The Pittsburgh District will continue demolishing the dam, then move on to the next phase of removing lock walls, with work beginning in 2025 and expected to last until at least 2027.
The removal of the locks and dam at Elizabeth represents the final phase of the Lower Mon Mega Project. The project also involved installation of a new gated dam at Braddock (Locks and Dam 2), replacing the former fixed-crest dam, and a new, expanded riverside lock chamber at Charleroi (Locks and Dam 4). Once complete, the Pittsburgh District said the project is expected to bring an economic benefit of $200 million annually, including cost-time savings in transporting commodities through the region using inland navigation and reduced maintenance costs.
Monongahela River Locks and Dam 3 at Elizabeth had operated since 1907, but the district said it was prone to flooding and shut down operations during high-water events, resulting in navigation delays.
