WEBVTT

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(gentle music)

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- [Narrator] The history
of the Monongahela River

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Navigation System, US
Army Corps of Engineers.

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The US Army Corps of Engineers

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acquired the Monongahela
Navigation System,

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originally built by the
Monongahela Navigation Company.

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The Monongahela Navigation Company

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built the earliest locks and dams

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on the Monongahela River in Pennsylvania

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between 1838 and 1897.

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The US Army Corps of Engineers

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acquired the Monongahela
Navigation Company facilities

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in Pennsylvania, including Locks
and Dam 2, near Port Perry,

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Locks and Dam 3 near Elizabeth,

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and Locks and Dam 4 near North Charleroi.

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By the 1870s, the United
States Army Corps of Engineers

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had begun constructing locks and dams

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on the Upper Monongahela in West Virginia.

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In the early years of the 20th century,

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they began replacing old locks and dams

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on the lower portion of the river.

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The first to be replaced
was Lock and Dam Number 2,

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which was rebuilt from 1902 to 1906.

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Lock and Dam Number 2 had two locks

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and a concrete dam with
a removable Chittenden.

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- Ground was broken in 1901 to 1904,

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when it was determined

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that a lock and dam structure

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was gonna be built at this facility.

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That consisted of two chambers.

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They were both 56 feet
wide by 300 feet long,

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and it also had two houses that were here,

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along with a small maintenance shed.

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Then in 1948-49,

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they began reconstruction of the facility.

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They had identified some issues

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with the original construction.

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The concrete was very poor.

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So what they did was they decided

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to build on top of the old facility,

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and what they did there
was in the riverside,

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they built an actual new chamber,

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which was the new river chamber,

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and that was gonna be 56
feet wide by 360 feet long,

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and that was opened up in 1950.

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In 1951,

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they began rebuilding the land
chamber and the land wall.

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What they began to do was
dismantle the old middle wall

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and rebuild this new chamber,

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so it was now going to be 720
feet long by 110 feet wide.

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It was the first of
its kind in the region.

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It's also the largest chamber

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in the Commonwealth of Pennsylvania.

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One of the other unique
structures that they built

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on the auxiliary chamber

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was what's called the floodway bulkhead.

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And what that is, is an
opportunity to widen the river

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an additional 56 feet in
high water conditions,

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because the river is kind of narrow here

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in the Braddock area.

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So once we start experiencing high water,

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we can actually widen
the river another 56 feet

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by the use of that floodway bulkhead.

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(gentle music)

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In the '90s it was
determined that a new dam

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needed to be put in, which
is what became now known

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as the Lower Mon Project.

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A design was built, and it
was the first of its kind

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in the Army Corps of Engineer history

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where it was gonna be constructed
what's called in the wet.

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So down in Leetsdale, they
actually excavated a huge pit

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and they began casting and installing

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all these panels together and forming

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the base structure of the dam,

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and that was gonna be done in two parts.

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What the plan was is
they would build the dam,

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the base part of it, and then raise it up

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in a coffer dam and literally
float it up the Ohio River

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and then up the Monongahela,

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bring it in place and then sink it down.

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And they did this twice,

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and it was amazing to watch them do it.

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It was like the ninth wonder of the world.

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Absolutely fantastic.

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But this was the first
time the Corps of Engineers

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had ever done an in the wet construction.

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When they lowered both sections down,

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they were within one-eighth of an inch

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of where they needed to be.

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It was absolutely amazing, the precision.

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But then again, this was 2000.

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Once 2004 came around,

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they had completed the
construction of the new dam

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and began demolition of
the old fixed crest dam.

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- [Narrator] The next
Lock and Dam replaced

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was old Lock and Dam Number
3, from 1905 to 1908.

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Like new Lock and Dam Number 2,

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the new Lock and Dam Number 3

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had two locks and a concrete dam

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with a movable Chittenden drum weir.

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- Construction started in 1903.

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It was completed in 1907,

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and it's worked continuously since then,

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with a major rehab
completed in the late '70s.

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Actually, it actually operates quite well

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considering its age and usage,

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'cause we are one of
the busier projects here

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in the Pittsburgh District.

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- The next lock and dam replaced

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was old Lock and Dam Number
4, from 1905 to 1908.

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- The original Lock, and you
can actually still see it

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if you go outside and look
downstream past the bridge,

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was completed somewhere around 1903

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and it was on the left
ascending bank of the river

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with a fixed crest dam.

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And they learned very quickly

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that they shouldn't have put it there.

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It just, the entrance
and angle and exit angle

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for the vessels was just
too difficult to make.

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They had a lot of accidents.

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The construction at the
site we're currently at

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started in about 1926, and they decided

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to move the chamber up
about a quarter of a mile

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and put it on the right descending bank

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to make entrance and exit a lot easier,

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get above the bridge.

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We slowly progressed toward the project

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that's going on now,

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where we need to make
the lock chamber bigger.

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So we took out the
auxiliary chamber in 2003

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and began construction
of the new river chamber.

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That's gonna make the chamber bigger.

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The same length, so it's
still 720 feet long,

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but it's gonna be 84
feet wide instead of 56.

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And what that does is it
increases the efficiency.

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We can get more barges in that chamber

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than we can in this one,

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so it'll make it a little
more efficient for industry

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to get their barges through.

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(gentle music continues)

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- Well, with the removal
of Lock and Dam 3,

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that will really facilitate opening up

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that part of the river.

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So we'll have a 30-mile stretch unimpeded

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by any navigation
structures, which I think

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will really invite people
to come to the river

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without having to deal
with those blockages

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on that 30-mile stretch and
just be, clean, clear water.

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(gentle music continues)