The main lock chamber at the Greenup Dam should be open and barges moving through it by Oct. 5, when work on new upper lock gates is finished, U.S. Army Corps of Engineers officials said Tuesday.
Workers are making final adjustments and preparing for a last inspection before moving their equipment out and reopening the chamber, said project engineer Steve Hann.
Once the chamber is reopened, traffic through the lock will speed up dramatically, when the now seven-hour wait is shortened to an hour.
There are four of the gates, one pair at each end of the chamber. The gate being replaced is at the upriver end of the lock chamber. Replacement of the lower gate is scheduled for 2014.
The 290-ton gates, each 60 feet by 60 feet and 5 feet thick, close to fill the chamber with water. The final adjustments will square up the gates so when they close they will meet precisely in the center. They are engineered so they will converge with a quarter of an inch or less of difference, Hann said.
The project included new gates and the massive hinges they swing on. Made in sections in Birmingham, Ala., by the Steward Machine Co. and floated upriver by barge after being assembled in St. Louis, the gates are expected to last at least half a century and likely longer.
They replace gates installed in 1959 that had worn out from 50 years of holding back 1,800 tons of water pressure. Wear was increased over time as the enormous pressure was applied and then relieved with each filling and emptying of the chamber. That caused a sort of stressing and flexing similar to repeated bending of a coat hanger, said project manager Mike Keathley.
The Greenup job is only the second use of the design and technology to install replacement gates that meet modern standards, and the first in a main lock chamber, Hann said.
A previous replacement of auxiliary chamber gates at the Meldahl locks near Cincinnati helped engineers refine the process in Greenup and the Greenup project yielded further refinements, he said.
Plans for two more gate replacements are in the works, the lower Greenup gates and the main Meldahl gates. The Greenup gates are being manufactured now.
Gates at other locks up and down the river are aging and doubtless will require replacement in the decades ahead, Keathley said. “We’re trying to get ahead of the maintenance curve so industry can be ready and ship early as needed.”
When the 1,200-foot main locks are closed it increases the wait time to pass through because longer tows have to be divided in two to pass through the 600-foot auxiliary locks. When that happens the corps and shippers schedule lock times accordingly. If there is an emergency such as a malfunction in the auxiliary lock, barges typically have to wait 48 hours or more. “Basically you’ve shut down the river,” Keathley said.
The Greenup lock system is one of the busiest on the Ohio River, with an average of 64 million tons of shipping per year passing through. It has been closed several times in recent years, including 26 days in 2010, which resulted in industry-wide losses of about $5.2 million, according to corps spokesman Brian Maka.
MIKE JAMES can be reached at email@example.com or (606) 326-2652.