Photo By Mark Rankin | Lock and Dam Mechanic Craig Smith, U.S. Army Corps of Engineers Nashville District...... read more read more
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HIXSON, Tenn. – Teamwork and a valuable dialogue between the U.S. Army Corps of Engineers Nashville District and Tennessee Valley Authority led to a quick repair action that reopened Chickamauga Lock this week to commercial barges and recreational vessels moving up and down the Tennessee River.
A routine inspection of the lock revealed cracks in the concrete surrounding the upper land miter gate embedded anchors. This led to closer examination of both the land and river wall anchorages Oct. 27. During the inspection, the team found a crack in a steel member on the upper river side, which forced the Corps to close the lock to river traffic.
The Nashville District immediately dispatched a repair team and several maintenance vessels to begin preparations to fix the problem. The Corps collaborated very closely with TVA officials to investigate and determine the structural integrity of the anchorage.
Jeff Ross, Nashville District Navigation Branch chief, said the crack was significant because of its proximity to the exposed member that carries the bulk of the weight of the upper lock gate while it is in motion.
“Thankfully, the crack didn’t extend beyond an area that could be repaired by simply chipping out a limited amount of concrete,” Ross said. “It was feared that the entire embedded anchorage would have to be exposed to accomplish the repair, which would have led to a much longer and more expensive repair effort.”
Ross noted that the Corps enjoys a great working relationship with TVA, so it seemed very natural for engineers from both agencies to work closely together on a viable solution.
“This strong relationship was evident in the efforts to reopen Chickamauga Lock this week,” Ross said.
Brad Bishop, civil engineer in the Nashville District Navigation Branch, said TVA assisted with providing material, line boring of the holes for the anchorage pins, and final machining of the replacement pins. Corps personnel handled all dis assembly, welding repair, reassembly and installation, and making final adjustments of the anchorage, he said.
Chickamauga Lock reopened to navigation at 1 p.m., Nov. 4. The repairs were completed a week and a half earlier than projected because of the quick movement of resources and coordination between agencies, Ross noted.
“The teamwork between the Corps and TVA made the difference in a timely repair. It was essential in getting the lock reopened to commerce on the river,” said Lt. Col. John L. Hudson, Nashville District commander.
Hudson said the district took full advantage of being able to move a portion of its repair fleet from Wheeler Lock in Florence, Ala., to Chickamauga Lock, which had a lot to do with making the quick response possible.
“The Nashville District’s Motor Vessel Warioto was involved in periodic repairs at Wheeler Lock,” Hudson said. “We moved the Warioto, a derrick boat and key personnel into position at Chickamauga Lock to disassemble the gate, help with the repair, and then with reassembly. If we didn’t have those resources close by it would have taken much longer to reopen the lock.”
The Nashville District continues to monitor the upper gates and embedded anchorage. Installation of additional monitoring instrumentation will provide engineers data for future maintenance, and also for engineering design and fabrication of new embedded anchors for a more permanent fix.
TVA also lauded its partnership with the Corps and a positive outcome that positively impacted the many stakeholders that utilize the lock to move up and down the river.
“The speed and success of the Chickamauga lock repair is a testament to the close working relationship TVA has always shared with the Corps,” said David Bowling, TVA River Management general manager. “Through pooling our collective engineering and fabrication capabilities, we were able to respond faster than we could have working separately and restore vital navigation capacity to the full Tennessee River system.”
Matt Emmons, the lockmaster at Chickamauga Lock, said the synergized effort between TVA and the Corps led to a quality repair that maintenance personnel executed in a timely manner. Getting the lock reopened matters a lot, he said, because closures cause layoffs and impacts families, and also diminishes confidence in waterborne transportation.
During the closure of the lock, Emmons said he visited the captain and crew of the Motor Vessel Jodi McMinn, an asphalt tow, which waited eight days to return downstream with its empty barges.
“This was very gratifying to me because a lock closure is all about people to me and how their lives are being impacted by it,” Emmons said.
When the lock reopened, Emmons said it was good to see traffic moving again, including the Motor Vessel Pioneer, which moved upstream to deliver a 200-ton generator stator for TVA to the Kingston Fossil Plant.
“We had a lot of positive comments from folks because everyone seemed astonished at how quickly the work progressed,” Emmons added. “As the lockmaster, I have a deep personal commitment and consider it a serious responsibility to keep the lock open for so many different interests. Over the past seven years I have gained an increasing awareness regarding just how many people, jobs, families, and lives get negatively impacted in a real way when we have to close the lock for whatever reason.”
TVA completed construction of Chickamauga Lock and Dam in 1940. A single chamber measuring 60-by-360 feet, the lock has since 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. Even with costly advanced maintenance procedures, the concrete expansion threatens the structural integrity of the lock and limits its life span.
Ross said it’s entirely possible that there is a connection between the expansion of concrete structures and the cracked anchorage member.
The Nashville District continues to maintain Chickamauga Lock while a project to construct a replacement lock is suspended due to a lack of funding. The most recent construction activity on the project includes completion of the cofferdam and off-site fabrication of the miter gates, culvert valves, culvert bulkheads and approach wall beams, all completed in 2013. The project is not in the president's fiscal year 2015 budget, and will remain in a temporary suspended status until additional funding becomes available to continue construction.
The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at www.lrn.usace.army.mil, on Facebook at http://www.facebook.com/nashvillecorps and on Twitter at http://www.twitter.com/nashvillecorps.
| Date Taken: | 11.07.2014 |
| Date Posted: | 11.07.2014 17:11 |
| Story ID: | 147403 |
| Location: | HIXSON, TN, US |
| Web Views: | 52 |
| Downloads: | 0 |
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