Southern Illinois Project
Dam the Ohio River!
by
Craig Barner The epic $1.4 billion Olmsted Locks and Dam began in southern
Illinois in November 1992, and this summer crews are preparing to start assembling
the $564 million dam, which should be complete in 2013.
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The project on the Ohio River moved into a new stage in July
2004 when crews were mobilized to construct the dam, said Richard Schipp, resident
engineer with the U.S. Army Corps of Engineers, the federal agency overseeing
the project.
Tony Sandor, a project manager with Boise-based Washington
Group International, a member of the Washington/Alberici Constructors Inc. Joint
Venture serving as the general contractor, said the preparatory work includes
the 1,000-ft.-long, 300-ft.-wide yard to be used to form the precast dam pieces,
or "shells;" 1,600-ft.-long skidway with rail and rollers to transport
the shells to the river edge; and work areas.
The 2,700-ft.-long dam will
feature tainter gates adjacent to locks on the Illinois side, fixed weir on the
Kentucky side and traditional wicket gates in the middle. In the spring, when
the river level is high, barges will cruise above the submerged wicket gates without
stopping.
"It's much cheaper for the industry to never have to stop,
wait in line [for lock space] and then go through," added Larry Bibelhauser,
Olmsted project manager for the Corps of Engineers.
When river levels are
low, the dam will be used to maintain the pool for the 45 mi. between Olmsted
and the Smithland Locks & Dam in Hamletsburg, Ill. In this situation, the
wicket gates will be partly above water at Olmsted, and river craft will use the
locks to pass.
The locks feature two 110-ft.-wide, 1,200-ft.-long chambers.
After
barges enter a chamber, the miter gates close. Valves are opened to let water
in the chamber and elevate the craft, or valves are opened to let water out and
lower the craft, depending on whether it is going upstream or downstream.
The
chamber's water level changes as the pressure equalizes. "There is no pump,"
Bibelhauser added. "It's all based on gravity."
When the water
level is at the desired level, the miter gates at the other end of the chamber
open to permit the craft to exit.
One for Two The
Olmsted project is replacing Locks and Dams No. 52 and 53 upstream. The antiquated
structures, which were completed in1929, can no longer handle river traffic without
significant delay.
"This dam (Olmsted) will probably have to operate
about the same frequency as 52" or about 40 percent of the year, Bibelhauser
said.
Nos. 52 and 53 are the last of more than 50 locks and dams from the
late 19th and early 20th centuries that will have been replaced on the Ohio since
the 1950s between Pittsburgh and southern Illinois.
Nos. 52 and 53 will
be demolished, and the project is expected to be complete in 2014.
"This
is the busiest stretch of river [in the United States] as far as tonnage goes
mainly because you're in an important junction," Bibelhauser said.
About
100 million tons of cargo - coal, grain, petroleum - are carried annually on barges
between Cairo, Ill., and Paducah, Ky. They can go east to Cincinnati or Pittsburgh;
or west to New Orleans or St. Louis via the Mississippi River.
A federal
appropriation covers half the Olmsted project cost, and the Inland Waterways Trust
Fund covers the other half. The navigation industry pays a tax on diesel fuel
that goes into the fund.
$600 Million Completed Previous
to the dam, about a dozen contracts valued at about $600 million were completed.
The
major elements included a $65.7 million lock cofferdam, the $271.6 million lock
and the $106.7 million approach walls.
Lock Cofferdam:
A
temporary lock cofferdam was constructed between June 1993 and December 1995 to
expose a portion of the river bottom immediately adjacent to the shore. Once the
river bottom was dry, the lock was constructed.
More than 8,500 109-ft.-long
sheets were driven into the river bottom with a pile-driving hammer on a barge.
Laid end to end, the sheets would have stretched 171 mi.
"They were
the longest sheets Bethlehem Steel had ever made," the Corps of Engineers'
Schipp added.
The interlocked sheets created 51 circular cells, some 64
ft. in diameter, which formed the cofferdam's rectangular perimeter.
"Generally,
you drive the sheet 5 ft. down, go to the next and drive it and go around the
cell," Schipp said. "You make several passes until you get 15 to 20
ft. down into the soil."
Mud from the river bottom was dredged and
pumped into the hollow cells for sturdiness.
Up to 15 barges were being
used at a single time during the cofferdam project.
Lock: The
lock was constructed between December 1995 and November 2001.
Because the
project lies in the New Madrid Seismic Zone, the lock needs to be secure in case
of an earthquake, Bibelhauser said.
As a result, 12,000 45-ft.-long steel
H-piles were driven into the ground, and rebar was set.
In March 1997,
a major setback occurred when the river flooded and water poured over the cofferdam
perimeter. By May, the water had receded, and about 1 ft. of mud had been deposited.
Machinery
was brought in to suck up the dry mud, but the results were only so-so. In the
end, hand labor was used to remove the mud.
About $15 million and six months
were required for the remediation, Bibelhauser said.
The government, contractor
and contractor's insurer each ponied up the money.
Once the cleaning was
complete, concrete pours began, and about 700,000 cu. yds. were poured. A 12-ft.-thick
slab forms the lock bottom, and three walls - land, middle and river - lie on
top.
"Inside those walls is a box culvert, and that's where we let
the water in and out to be able to raise and lower the barges [in the chamber],"
Bibelhauser said.
When the lock was complete, the cells were removed to
flood the lock.
Approach Walls: Because the typical
barge has three 35-ft.-long tows, approach walls are needed to guide the craft
into the locks.
"You're trying to get the front that is a quarter-mile
away while you're pushing the barge from the back [where the motor is],"
Schipp said. "Those walls are important."
There are four approach
walls of varying length, with the longest a third-mile long.
Because the
river's height will fluctuate, the approach walls will occasionally become submerged
and muddy.
As a result, floating guide walls were designed to reduce maintenance
costs.
Eleven 375-ft.-long segments that make up the approach walls were
built in a "graving yard" in Paducah, towed to the site, assembled in
the lock chamber with bolts and set.
Four nose piers made up of three,
linked 10-ft.-diameter pipes filled with concrete and steel were installed at
the tip of the approach walls as protection.
"You have to have something
pretty substantial out there when that big tow comes through," Bibelhauser
said. "It might lose control, high water might twist him around or the wind
might blow."SIDEBAR Designing
a Dam A hope in planning the design of the Olmsted dam was to eliminate
a wicket gate-only dam.
When a wicket-gate dam needs to be open or closed,
a dam tender in a boat with rod hooks the door-like wickets that shut against
the dam's sill, said Larry Bibelhauser, Olmsted project manager for the U.S. Army
Corps of Engineers, the federal agency overseeing the project. "It's kind
of a dangerous job," he added.
The design of the 2,700-ft.-long dam
calls for five-bay tainter gates near the Illinois side, traditional wicket gates
in the middle and a fixed weir on the Kentucky side. The design has advantages.
The
140 wickets stretch 1,400 ft., and in high water, the gates will be submerged
and allow boats to float above.
In addition, the tainter gates permit for
better control of the pool. This is an advantage
in a region where hydropower
generation upstream can produce a sudden rush of water downstream during peak
summer electrical demand.
"The hydropower guys can open up the water,
let the water go through to generate electricity and shut it off an hour later,"
Bibelhauser said. "That tends to screw with the guys [downstream].
"I
got these [tainter] gates and don't have to worry about that. I push a button,
change it (the pool) and control it better."
The concrete tainter
gate shells - including stilling basin, sills and piers - will be fabricated on
shore. Then they will be moved to the river edge via a skidway, set on a lifting
frame and moved into the river on a catamaran barge with 5,000-ton lifting capacity.
"Think
of the concrete shell piece as a shoebox that you take the lid off and turn upside
down," said Richard Schipp, resident engineer with the Corps of Engineers.
The
shells are lowered, and the tremie concrete that is typically used under water
will be pumped under the shell, forcing out the water. |
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