St. Louis – Monday, April 26 – The U.S. Army Corps of Engineers in St. Louis continues work to correct two problems that emerged Thursday, with the incidents at Dam 25 near Winfield, Mo., and problems with the Mississippi River navigation channel above Grafton, Ill.

At Dam 25 near Winfield, a large steel dam gate some 100-feet long, failed when the chain mechanism that raises and lowers it broke at its connection point.  The failure has been attributed to a faulty mechanical-electric limit switch.  It occurred while lock maintenance personnel were lubricating the dam’s gate chains.

The gate, called a roller gate, is in the middle of the 1,296-foot dam that controls water depths upstream to Lock and Dam 24 at Clarksville, Mo.  It is one of three such gates that are accompanied by 14 gates of another design in the dam.

St. Louis District officials emphasized that the problem at the dam does not present a hazard to the public.  Failing to correct it could have serious impacts on commercial river transportation, but the dams on the river are not public safety flood control structures.

Personnel from St. Louis’ District Service Base and other Locks and Dams in the District are working to adapt a set of bulkheads, known as stop logs, to isolate the damaged gate from the river’s flow.  The stop logs being installed were rushed from the Corps’ Lock 17 at New Boston, Ill. over the weekend. 

Moving the bulkheads, too large to be truck transportable, over the weekend became necessary when structural engineers in St. Louis assessed the bulkheads on hand at Lock and Dam 25 as being in very poor material condition.  While repair technicians went to work to correct damage from aging and corrosion, a plan to borrow bulkheads from the Rock Island District was set in motion.

In a fortunate circumstance, St. Paul District Corps tow boat, MV Warren, was pushing the St. Louis District’s heavy lift crane, Sewell, to St. Louis at the time.  Sewell had wintered over in the St. Paul District, support work in Minnesota.  Warren and Sewell were ordered to stop at Lock 17, add a barge carrying the needed bulkheads to its tow and continue at best speed to bring the bulkheads to Dam 25 at Winfield.  The barge carrying the bulkheads arrived at Dam 25 Sunday evening.

Until this past weekend, water control experts in St. Louis had been planning to start to close dam gates at Lock 25 to “catch pool,” as early as Sunday. The gates had been open most of the spring to allow heavy flows from snow melt, saturated soils and rain to move down river.  

But over the weekend, precipitation further up the Mississippi River changed the timing for catching pool, delaying that operation at Dam 25 until about Wednesday.  This is enabling personnel to complete adapting the bulkheads borrowed from Rock Island and install them above the damaged gate.

St. Louis structural Engineer Rob Kelsey said the bulkheads that arrived Sunday evening are in much better shape than those on hand at the site.  He said there is much greater confidence that they will provide the needed margin of safety to repair the damaged gate.

St. Louis Engineer District Commander, Col. Thomas O’Hara, said the work shows the value of regionalization efforts in recent years.  “Our crane was in the St. Paul District.  We had been helping them.  The Rock Island District had bulkheads that we needed on short notice.  The St. Paul District was returning our crane to St. Louis and was able to pick up the needed items en route and deliver them along with our crane.  We are one Corps, we speak the same language and we are a great team,” he said.

There is no firm estimate at this time of either costs to repair the dam gate or how long the work will take. 

The aging steel sprockets and chains at both Dams 24 in Clarksville, Mo., and Dam 25 at Winfield had previously been scheduled for replacement this summer using American Recovery and Reinvestment Act (ARRA) funding.  This work will go forward this summer.

Elsewhere, the District’s dredge Potter got underway ahead of schedule Sunday to travel to River Mile 221.2, three mile above Grafton, Ill., to dredge there.  A barge tow bumped there in a narrowing navigation channel last week.  The barge tow suffered no damages and was able to proceed up river without assistance.

Both the Corps of Engineers and Coast Guard had noted channel narrowing there due to sedimentation that started to occur with recently reduced river flows, and cautioned mariners passing through the area.  With the channel already narrowed and continuing to lose width, the St. Louis Engineer District elected to remobilize its dredge Potter to reestablish a safe navigation channel at least 9 feet deep and 300 feet wide.  Potter had been in standby since the end of the dredging season in December 2009 and its crew had to be reassembled and steps take to reactivate the diesel-electric-powered vessel for duty.

The U.S. Army Corps of Engineers, U.S. Coast Guard and the navigation industry partner to monitor river conditions continuously, especially as river conditions change as they often do at this time of the year.  Corps of Engineers and Coast Guard vessels routinely scan the navigation channel with sonar and relocate channel buoys to continue to define a safe channel.  As shown by the current response, the Army Corps of Engineers stands ready to remobilize dredging assets to be employed when and where river conditions dictate that need.

– 30 –

[Printable PDF}

Previous: Corps  of Engineers in St. Louis responding to Mississippi River Incidents

Lock and Dam 25 near Winfield, Mo. (file photo)