After more than 30 years of planning and construction, one of the most important segments of the U.S. inland waterway system — the Olmsted Lock & Dam (L&D) — has been completed. The U.S. Army Corps of Engineers' (Corps) Louisville (Ky.) District held a ribbon-cutting ceremony on Aug. 30.

According to the Corps, more tonnage passes through this point than any other place in America’s inland navigation system. Olmsted L&D is sited on a strategic reach of the Ohio River that provides a connection between the Mississippi, Tennessee and Cumberland rivers.

It is the largest Corps project since the Panama Canal. The project, officially called the Locks & Dams 52 & 53 Replacement Project, consists of two 110 ft.-wide by 1,200 ft.-long locks, adjacent to the Illinois side of the river, and a dam that spans the river and connects with Kentucky. Additionally, there are 140 wickets and a fixed weir.

From 2013 to 2017, Ohio River L&D 52 handled, on average, about 78.2 million tons per year. During that time, corn, soybeans, fertilizers, feed products, wheat and other agricultural products represented about 22% of all tonnages handled by Ohio River L&D 52.

About 83% of the corn and soybean shipments were down-bound movements. Up-bound shipments accounted for 17% of corn and soybean movements through L&D 52, indicating that some corn and soybeans from the Midwest are delivered to domestic markets from the Mississippi River with eventual destinations up-river on the Ohio, Tennessee or Cumberland rivers.

Related:Ohio River Lock & Dam 52 reopens

“Once fully operational, Olmstead will provide much-needed reliability and an average annual economic benefit of approximately $640 million per year,” Senate majority leader Mitch McConnell (R., Ky.) said. “It will be the linchpin of our country’s incredible waterways system.”

Due to closures at the locks, especially L&D 52, there have been days-long delays as barges waited for needed repairs to transit the obsolete locks, according to the "Grain Transportation Report" (GTR) compiled by the U.S. Department of Agriculture’s Agricultural Marketing Service.

The Olmsted project is unique for using a method known as “in-the-wet” construction in which large concrete shells were cast on land and then placed in the river to form part of the permanent dam. This method avoids the construction of cofferdams that form dry areas of river bottom to build the dam and lessens the impact on navigation during construction.

Another part of the project is a moveable dam that allows barge traffic to bypass the locks through a 1,400 ft.-wide navigable pass when river levels are high enough. The moveable dam consists of 140 ten-foot-wide wickets that — under high-water conditions — can be lowered to lay flat on the river bottom to allow barge traffic to flow unrestricted by the submerged wickets. “When water levels are lower, barges must use the locks to traverse the river, so the wickets are raised to form a dam that accumulates a pool of water large enough for safely operating the locks,” the GTR noted.

The Olmstead L&D has been a poster child for how the skyrocketing costs of current waterway projects require receiving the right appropriation levels from Congress. The Olmsted L&D project was authorized by the Water Resources Development Act of 1988 at an estimated cost of $775 million at the time. However, the final cost soared to $2.7 billion.

According to the Corps, the cost increase, from $775 million to $2.7 billion, was caused by a variety of factors. “The new dam technology required one-of-a-kind equipment for heavy lifting, moving and setting large concrete shells to accurate locations and other associated procedures. The cost of these technologies became more expensive than anticipated,” the GTR explained.

Adding to overall cost increases were funding shortages that slowed project progress and inflation over 30 years. Normally, the construction season runs from May to November, when lower water conditions make it more advantageous to work in the river. However, high water conditions in some years, at inopportune times, caused serious construction delays and increased costs.

“Without the disruptions caused by the L&Ds 52 and 53, the newly completed Olmsted L&D replacement will provide a reliable and efficient transportation component for a vital segment of the river system — a system that provides transportation for about half of U.S. corn and soybean exports from interior production areas to seaports for eventual shipment to foreign markets,” Nick Marathon wrote in the GTR for USDA.