While Congress debates more funding, Olmsted construction presses onJan 23, 2014 05:04 PM
A URS pile-drive crew approaches a dive barge working on the Olmsted Locks and Dam project. In the background is a catamaran barge, which is used to transport precast sill shells.
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On a pleasant morning in August, Jon Leite, a diver with Global Diving & Salvage, entered the Ohio River between Cairo, Ill., and Paducah, Ky., and disappeared into what is arguably the most scrutinized project on America’s inland river system.
The word eternity rises to describe the timeline of the Olmsted Locks and Dam project, begun in 1997 to replace the aging and crumbling locks 52 and 53, built in the 1920s. Originally expected to be completed in 2008, new projections put completion in 2020 — or 2024 if you include demolishing the existing locks.
From a viewpoint above the site, the scene below resembles a Hollywood set with monolithic equipment looking like temples to the God, Aqua. The new lock structures look like elongated moats straddled by a castle emboldened with the medieval insignia of the Army Corps of Engineers (USACE).
Nick Finney, a supervisor with Global Diving & Salvage, demonstrates the pile and sheet interlocking system at the multi-billion-dollar construction site near Paducah, Ky.
Over-budget Hollywood epics pale in comparison to the cost overruns of the Olmsted project. Originally estimated to cost about $775 million, it is now projected to cost $3.1 billion when it is finished. However, weather, river conditions and funding fluctuations — issues that are in part blamed for the delays and cost explosion of the past — are still there for the project to contend with in the future. But the main culprit has been identified as the construction process adopted by the Corps to build the dam.
According to the USACE, the old locks are the highest-tonnage locks in the nation’s barge transportation system, rendering the replacement project necessary despite the ever-increasing cost. The deteriorating structures needed constant and expensive maintenance and repair. As a temporary measure during the ’60s and ’70s, the lock chambers were lengthened from 600 feet to 1,200 feet to accommodate the larger tows that theretofore were required to lock through twice, a process that creates tow backups and drives up the cost of barge transportation.
The locks portion of the project, consisting of two 110-by-1,200-foot lock chambers located along the Illinois shoreline, was completed by the Corps in 2002. Idle, they await the dam, a structure that, when complete, will consist of five Tainter gates and a 1,400-foot navigable pass and wicket dam. A Tainter gate, named for structural engineer Jeremiah Tainter, is a radial arm floodgate. URS, an international engineering and construction company, was contracted in a joint venture with Alberici Constructors to construct the dam.
Stilling Shell 5 is attached to the transport frame and on its cradle.
The dam, at mile marker 964.4, will create an upriver pool extending to the Smithland Lock and Dam at mile marker 918.5. The pool will encompass the confluence of the Cumberland and Tennessee rivers with the Ohio River, including the inland river transportation hub of Paducah, Ky., dubbed the towboat capital of the inland river system.
The Corps has weathered a barrage of criticism for the cost and inefficiencies of the project that has siphoned off the lion’s share of money for infrastructure construction and repair from the Inland Waterways Trust Fund. The fund’s coffer is composed of a 50/50 split between federal general treasury money and a 20-cent-per-gallon tax on fuel burned by the barge and towing industry.
Most of the criticism concerns the Corps’ choice of construction methods for the dam portion of the project. Instead of building a conventional cofferdam around the construction site, they chose a process called “in-the-wet,” whereby the massive concrete sill components are precast on land and transported on the river to the site and set in place. The Corps could not attract bidders for a traditional fixed-price contract because of the unknowns and the risk that “in-the-wet” construction presented in the deep and fluctuating lower Ohio River. The present joint venture to construct the dam was created in 2002 and is a cost-plus contract.
The unproven methodology was adopted after a Corps study determined that fabricating in-the-wet would be faster and less expensive than building a cofferdam. But in practice, that theory has been turned inside out.
Each Tainter gate consists of a sill shell, stilling basin shell and a lower pier shell. There are 12 additional shells that make up the navigable pass that will take the wickets. The precast shells are 2 feet thick with a waffle pattern on the underside to keep weight down for transport. The shells must be moved carefully to prevent cracking.
“This type of construction, on this scale, has never been done before,” said Wade Miller, marine engineering manager for URS.
As each sill is completed, a 45-foot-high lifting frame is attached and a 5,000-ton gantry crane, the largest of its kind in the world, is moved over the frame. The frame is attached utilizing the world’s largest strand jacks, lifted, and then set down on a large cradle. The frame, shell and cradle are then moved at one-foot per minute down a skid-way into the water where the world’s largest catamaran barge waits.
A tug moves the barge over the lifting frame and locks onto the frame with bolts turned by the world’s largest torque wrench. The frame and sill are lifted off the cradle and floated into position over a foundation that is spiked with 140 24-inch pipe foundation piles and 22 master piles. Each pile has to be driven precisely one inch horizontally and a quarter inch vertically to accept the incoming shells. Once the sill is set in place, the void between the underside of the shell and the foundation is filled with tremie concrete, placed utilizing tremie pipes. Tremie concrete is concrete that is placed underwater.