Lloyd — The bedrock of the Ohio River is visible at the bottom of the Greenup Dam’s main lock chamber, where workers are busy replacing the first of two miter gates, which keep traffic moving through the busy navigation lock.

With an emergency gate and bulkhead holding back the flow of water, the U.S. Army Corps of Engineers’ Huntington District work fleet, along with private contractors, are carefully removing the concrete-encased steel along the walls of the chamber where the gates are anchored.

Over the next two months, workers will entirely replace the miter gate on the upper end of the lock and its structural components. Replacement of the lower miter gate at the  other end of the lock is scheduled in 2014.

The miter gates were originally built in 1959 and have simply outlasted their 50-year life cycle. The 1,200-foot lock chamber at Greenup Dam is consistently one of the busiest on the Ohio River and the entire U.S. waterway system, but it has been plagued in recent years by unexpected closures.

“We had to take the gate out of commission a couple of times due to severe cracking,” said Wayne Budrus, chief of operations division for the Huntington District. “They are past their design life and past the number of cycles you can responsibly expect them to operate in their lifetime. They are just at a point where they need to be replaced. From a fatigue standpoint, they are just not reliable.”

Closures, including this one, at the main chamber create a backlog of vessels trying to lock through at Greenup. The auxiliary chamber is half the size of the main chamber and requires tows to be broken apart and locked through in sections.

This stretches out the time it takes to move through the lock. Whereas it normally takes a towboat and its barges roughly an hour to pass through the main lock, it is currently taking an average of six hours to get the same towboat and barges through the auxiliary lock.

David Smith, navigation co-chairman of the Huntington Waterways Association, said the continued slump in the economy and demand for coal are the only reasons delays are not much greater at this time. If the economy were ticking along at the same rate as it was in the early part of the decade, delays could stretch to 48 hours or longer, he said, as they have in the past when the miter gates at Greenup have failed unexpectedly.

Delays and failures cost money. When the main chamber closed for 28 days in 2010, it cost the barging community approximately $5.2 million, said Huntington District Commander Col. Steven T. McGugan. Between 2000 and 2011, McGugan said, the cost of failures to the barging community was $31 million.

The new gates will have a lifespan of 50 to 60 years, according to McGugan, and should increase the locks’ reliability substantially. The total cost of replacing both the upper and lower miter gate, is $11.5 million and is funded through the Corps’ operations and maintenance budget.

Replacing the gates is a massive operation, because of their size, weight and inherent importance to the locks operation.

The upper miter gate itself was fabricated in five sections by the Steward Machine Company in Birmingham, Ala. They were then transported by rail, then truck, to St. Louis, where they were welded and put together as one whole gate and placed on a barge.

At press time, the gates were making their way up the Ohio River, and were located somewhere upriver from the Markland Lock and Dam en route to Greenup. Each of the two leafs of miter gate that will be set in place weighs in at 240 tons.

 The upper miter gate will be set into place by a large floating crane the Corp’s Marietta, Ohio-based fleet will move into place when it arrives.

The main lock is expected to be reopened in September.

CARRIE STAMBAUGH can be reached at cstambaugh@dailyindependent.com or (606) 326-2653.