Giant cranes, floating construction barges and underwater divers were all a part of the scene at Lock and Dam 12 during the past few weeks, as the four miter gates are being replaced at Lock and Dam 12.

The project, which includes the gates, pintle balls, strut arms and anchor bars, comes at a cost of $3.69 million, according to Army Corps of Engineers officials.

“The Rock Island District Mississippi River Project has been in the process of systematically replacing miter gates at all of our Lock Sites for nearly the last 10 years,” said Bellevue Lockmaster John J. Mueller, who added that the work at Lock and Dam 12 will complete a long-term goal of improving reliability at these critical sites and will be accomplished with in-house government employees and equipment, including the Quad Cities’ Heavy Lift Crane.

The original gates were 85 years old and were fabricated in place, meaning they were custom-built for the site and weighed 90 tons.

The new gates weighing in at 120 tons, were fabricated in Alabama and shipped up river. Along with the gates, the strut arms, the anchor bars and pintle balls are also being replaced.  

The strut arm is the connection between the operating machinery and the gate, the anchor bars are what connects the gate to the lock wall and the pintle ball is on the bottom of the lock chamber and that is what the gate sits on.

During the process, a 300-ton crane removes the old gate. Divers get in the water and inspect gate recess, gate sill, bubbler pipe and replace the pintle ball (which needs to be handled by a crane).

“The divers are 20 feet under water and unable to see, so the work is all completed by feel,” said Mueller. “There is radio communication between the divers and the crane operator.”

The new gate is set in place and connected to the anchor bars and strut arm, then leveling adjustments are made. The process takes 10-12 hours for each gate.

Mike Back, a Bellevue resident and Corps employee, is a diver for the Corps and is on site assisting with this project.   

Lock and Dam 12 in Bellevue is not only an integral part of the Mississippi River navigation system, it is an important part of both Bellevue’s general history, as well as its economic history.

Nearly 80 years ago, Lock and Dam 12 was under construction by the United States Army Corps of Engineers. Started in 1934, it was completed and open in 1939, just as World War II was breaking out in Europe.

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The new lock and dam system on the Upper Mississippi was constructed to ensure a four-foot navigation channel (later 9 feet) for steamships and commercial tows. It was the fourth of over a dozen locks in the Rock Island District, and was the fourth to go online.

President Franklin Delano Roosevelt’s “New Deal,” implemented nationally to help ease the employment woes of the Depression era, was the catalyst for the Lock and Dam project on the upper Mississippi.

It was a project of the Public Works Administration (WPA), part of that New Deal. The WPA was a large-scale public works construction agency, which was created by the National Recovery Industrial Act of 1933.

The agency, which spent over $9 billion over a 10-year period built large scale infrastructure projects, such as bridges, hospitals and schools, and of course, Lock and Dam 12 in Bellevue, which cost nearly $6 million ($106 million in today’s dollars).

Lock and Dam 12 is 556.7 miles above the confluence of the Mississippi and Ohio rivers. The complex stretches across the river at a point where the bluffs on the Iowa side are very close to the river; a complex of islands and sloughs extends nearly three-quarters of the way across the river from the Illinois side.

Bellevue State Park occupies the high ground on the Iowa side, while the urbanized area of Bellevue extends to the government-owned property on the flat land below the bluff.

The Lost Mound Unit of Upper Mississippi River National Wildlife and Fish Refuge occupies the islands, slough, and small flat bottom areas on the Illinois side.

The movable dam consists of seven submersible Tainter gates (20-feet high and 64-feet long) and three submersible roller gates (20-feet high and 100-feet long). The dam system also includes two, non-overflow, earth and sand-filled dikes; two transitional dikes; and a concrete-covered ogee spillway, submersible earth and sand-filled dike. The foundation is set in sand, gravel, and silt.

The lock dimensions are 110-feet wide by 600-feet long with additional provisions for an auxiliary lock. The normal upper pool elevation is 592 feet, approximately 15 feet above the tail waters below the dam at low water. The maximum lift is 9 feet with an average lift of 6 feet.

 It takes approximately 10 minutes to fill or empty the lock chamber. It takes about 8 hours for water to travel from Lock and Dam 11, in Dubuque, Iowa, to Lock and Dam 12.

The lock opened in 1938. During the peak of construction, a maximum of 960 men were employed at one time, many of them living right on the job site. For every one job on the Lock and Dam, it is estimated two more jobs were indirectly created in the local area.

The workers on the site used steam-powered cranes, while cement was mixed in two (2-cubic-yard) mixers that ran non-stop. Wood, limestone and local construction materials were used on most of the project.

Beside strong maintenance and a few remodel jobs (and a few near-floods) over the decades, the 80-year old facility looks and operates pretty much as it did when it went into operation in 1938. The gears, metal and concrete, as well as the main office itself is all original.

The existing 9-foot Channel Navigation Project was constructed in the 1930s and extends down the Upper Mississippi River from Minneapolis-St. Paul to its confluence with the Ohio River and up the Illinois Waterway to the Thomas J. O’Brien Lock in Chicago. It includes 37 Locks and approximately 1,200 miles of navigable waterway in Illinois, Iowa, Minnesota, Missouri, and Wisconsin.

The system’s 600-foot locks do not accommodate some of today’s modern tows without splitting and passing through the lock in two operations. This procedure requires uncoupling barges at midpoint which can triple locking times.

More than 580 manufacturing facilities, terminals, and docks ship and receive tonnage in the Upper Mississippi River basin.