By Lee Roberts
CHATTANOOGA, Tenn. (Feb. 28, 2017) – To gain a better perspective of the nation’s aging infrastructure on America’s waterways the senior official performing duties of secretary of the Army for Civil Works toured Chickamauga Lock today to realize the challenges of keeping a deteriorated lock open while racing against time to construct a replacement lock.
U.S. Army Corps of Engineers Nashville District officials briefed Douglas W. Lamont about the condition of the current lock and its replacement project, and then he walked along the lock walls where the Corps and Tennessee Valley Authority have installed more than 340 post-tensioned anchors and monitoring instrumentation that include over 2,900 data points, which are used to monitor concrete growth expansion and its erosive effects.
The lock opened to navigation in 1939. With a single chamber measuring 60-by-360 feet, the lock has experienced structural problems resulting from alkali aggregate reaction between the alkali in the cement and the rock aggregate, which results in a physical expansion of concrete structures.
Lamont called the visit “valuable” because although he has more than 40 years of experience as a civil engineer with the Corps of Engineers in the Jacksonville District and in Washington, D.C., before this visit he had not been to a lock and dam.
“It’s given me is an opportunity to look at the condition of the lock and to understand the alkali aggregate reaction,” Lamont said. “All the post tensioning anchoring work that you’ve done to keep this thing up to speed and continuing to go while you’re trying to move forward with a new replacement lock – that’s pretty admirable stuff that you’re doing in this district.”
Lt. Col. Stephen Murphy, Nashville District commander, informed Lamont that the Great Lakes and Ohio River Division has 12,000 miles of navigable waterways, 192 lock sites with 238 chambers, and that the division’s infrastructure amounts to 25 percent of the Corps of Engineers’ civil works budget.
Murphy also noted that the Nashville District has 10 dams, nine with hydropower, four locks in the Cumberland River Basin, and the average age of these projects is 63 years. He stressed that recreation is another important component. More than 31 million visitors recreate at the district’s projects annually – the district is the most visited in the Corps, has the highest campground utilization and largest marina concessionaire program, he said.
The district also partners with the Tennessee Valley Authority, who owns the projects in the Tennessee River Basin, but where the Nashville District maintains and operates the locks on the Tennessee River and Clinch River. Both organizations work together during drought and during flood events to manage the water for the best impact on the lower Ohio River and Mississippi River, said Mike Wilson, Nashville District deputy for Programs and Project Management.
“Regionally the aging infrastructure is a big piece of flood risk management,” Murphy said. “The Nashville District alone annually prevents about $15 million in flood damage.”
David Bowling, vice president of Land and River Management for TVA, also spoke to Lamont about TVA’s facilities in the Tennessee River Basin, which total 49 dams, 29 with hydropower. He also noted how TVA coordinates regarding water management with the Nashville District and Great Lakes and Ohio River Division during extreme events.
Diane Parks, Nashville District Operations Division chief, told Lamont that funding shortfalls for operations and maintenance appropriations have an impact on the ability to maintain, repair, replace and for major rehabilitation efforts. The strategy for USACE Asset Management is to repair and maintain based on the condition of projects, not necessarily based on the age of a project, she said.
“We could have newer facilities that are falling apart or need maintenance due to lack of attention or something like that, where we have older facilities in great condition,” Parks said. “There’s a blending here where we are looking more at condition assessments of the facilities.”
During the walking tour, Cory Richardson, Chickamauga Lock facility supervisor; Chickamauga Lock Replacement Project Manager Adam Walker, and Tommy Long, resident engineer, briefed the secretary on the deteriorating existing lock and the status of excavation work for the new 110-foot by 600-foot replacement lock.
According to Walker the growing concrete at the lock creates many problems.
“There are cracks and chunks of concrete have broken loose from the lock walls creating potential hazards for people and vessels transiting the lock. The lock has actually grown to be four inches taller and 12 inches longer than it was when it originally opened due to the concrete growth phenomenon,” Walker said.
Walker said the Corps has spent $29 million to date on efforts related to the expanding concrete, and stressed the benefit of a computer model that is periodically updated with new instrumentation data and allows the Nashville District and TVA to analyze existing stresses and forecast future stresses.
“Although collecting data from instruments is helpful in understanding the past behavior and present status of the lock, we also need the data to predict future problems. The model now has about 101,400 nodes, 81,400 solid elements and 19,600 surface contact elements. The model was calibrated and verified from field measurements and instrument data to help predict the future performance of the lock,” Walker said.
Chickamauga Lock has been closed at different times for unscheduled repairs, but Corps and TVA engineers and maintenance crews have kept the lock open even as the concrete continues to expand and hinder operations.
The long-term solution is a replacement lock that is currently under construction and Corps officials are working against time to keep the waterway open to commercial and recreational interests. There are three navigation locks and 318 navigable stream miles upstream of Chickamauga Lock that would be isolated from the Inland Waterways System if the lock is closed. This would present difficulties in transporting materials to upstream industries, including TVA nuclear power plants, U.S. Department of Energy facilities at Oak Ridge.
During Lamont’s tour, he also walked on top of the dam to get a good look at the coffer dam where work is ongoing to construct the new 110-by-600-foot lock. He said the interaction with everyone involved with keeping the old lock open and the new lock project moving forward is very beneficial.
“The other unique aspect to me is understanding the competitiveness from a funding standpoint how that really plays out in the ability to complete construction in a timely fashion versus schedules that are more drawn-out, (and) how the Inland Waterways Trust Fund impacts the ability to complete projects” Lamont said.
Lamont added that in general terms the nation’s infrastructure has been neglected, but the administration is talking more about highways, railroads, bridges, airports, utility systems, locks and dams – the waterborne nature of our economy, which is based on projects like Chickamauga Lock on the Tennessee River.
“To me it’s important from the standpoint that you obviously have to maintain what you’ve invested in. This project was completed in 1940 under FDR (President Franklin D. Roosevelt),” Lamont said. “And it’s amazing to me that the project continues to function with all the issues relative to the aggregate and the alkali reaction.”
Lamont added that he’s hopeful the new lock project can stay on track to realize the benefits of the project and to alleviate having to deal with possible future failures of the current lock.
The current lock chamber is also incompatible with today’s towing equipment resulting in longer than normal tow-processing times. When the new 110-by-600-foot lock is completed, it is expected to speed up the process of locking through, and would process up to nine jumbo barges in one lockage.
Richardson shared with Lamont that 3,085 pleasure craft locked through Chickamauga Lock (the most of any lock on the Tennessee River) and 906,678 tons of commodities moved through in 2016.
