WEBVTT

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(upbeat music)

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- The US Army Corps of
Engineers Nashville District

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has reached another huge
milestone with the placement

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of the tenth and final concrete shell

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for the Kentucky Lock Addition Project.

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This is the last piece of what will be

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the permanent lock wall for
the new navigation lock.

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It will also be used as
part of the cofferdam

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in order to do future excavation

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and construction in the dry.

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- Johnson Brothers, contractor
for the cofferdam project,

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set the final shell in
position February 2, 2020

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on the river bed below Kentucky Lock,

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where it will be part of the cofferdam

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and eventually a permanent
part of the new lock wall.

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The placement of the
1.7 million pound shell

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took place after the Tennessee River

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receded to a suitable elevation,

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following weeks of
delays due to high water

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at Tennessee Valley
Authority's Kentucky Dam.

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- We're putting concrete
on top of these shells.

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We're adding an additional
24 feet of concrete.

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So for the first five shells we placed,

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they were high enough out of the water,

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we were able to continue to place concrete

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on those during high water.

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So we haven't been sitting here idle,

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the problem is we haven't been working

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on the critical work during high water,

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and that's setting this tenth shell.

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- [Lee] The contractor emphasized

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constant communication
and attention to safety.

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Throughout the lift,

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the main objective involved
keeping the shell level

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and inching it into position

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because it's difficult to slow
down a heavy weight object,

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once it gets moving on the water.

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- We'll get it close as possible to grade,

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and then we'll tug it on into the keyway.

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Once we get it into the keyway,

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the divers will assist us

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hooking up the post tension rods

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that's tied back to the previous monolift,

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that's already anchored in concrete.

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That keeps the shell from shifting

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or moving once we're set and locked in.

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- [Lee] The Corps of
Engineers placed the first

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of ten concrete shells August 6, 2018.

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With each shell placed,

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the contractor and Army Engineers

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made communication a priority,

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to reduce risk and improve
methods and processes.

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- This is a massive undertaking,

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and it has been since
the fall of 2018 to now

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and February of 2020, to set ten of these.

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And that just shows that the contractor

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and the government both worked together

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and was able to do this.

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- [Lee] Aspects of the lift and technique

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used to place all ten concrete
shells with a gantry crane,

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is a unique engineering achievement.

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The contractor specifically designed

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and constructed the for the
downstream cofferdam contract,

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and it proved its worth yet again,

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with a final and heaviest lift.

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- Once the shell is set in the water

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and sitting on the spuds

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and we've locked it in with
our PT brackets on the side,

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the contractor has a lot of work to do

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to pour concrete inside that
shell and lock it in place.

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We'll come back in,

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maybe in a week or so,

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when that work is done

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and when all of those
sandbags are in place,

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and we'll pour it,

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we'll tremie concrete underwater and fill,

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what we call the plug,

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we'll put the plug in,

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which sort of locks the shell in place.

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- [Lee] The temporary portion
of the downstream cofferdam

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is the final step, that will
make it possible to excavate

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and then construct the new
lock in dry conditions.

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This is Lee Roberts reporting
for the Nashville District

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at the Kentucky Lock Addition Project

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in Grand Rivers, Kentucky.

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(upbeat music)