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Dredge Potter assists with emergency repairs at Lock and Dam 25
in Winfield, Missouri, Nov. 25, 2014. After engineers discovered
erosion along the overflow dike at Lock and Dam 25 the Dredge
Potter was brought in to assist in repairs before flooding could
threaten the stability of the dike. |
The Corps oldest dredge
wrapped up another successful dredging season on the Middle Mississippi, January
8.
The Potter and her crew of 50 began work on the muddy Mississippi River,
August 1 aiding the St. Louis District in achieving its mission of maintaining
a Congressionally-mandated 9-foot
deep, 300-foot wide navigation channel.
Within the St. Louis District,
dredging is performed on 300-miles of the Mississippi River, from Cairo up to
just below Hannibal, Missouri, as well as 80 miles of the Illinois River and 36
miles of the Kaskaskia River.
The 240-foot long, 46-foot
wide dustpan Dredge Potter was originally a steam-powered paddlewheel
before her transformation to a more modern diesel-electric power in 2001.
“Dustpan
dredges are very efficient on the main stem of the Mississippi River. They can
move easily in and out of traffic, and were specifically designed to move the
sand that’s in the Mississippi River,” Lance
Engle, dredging project manager with the St. Louis District said.
New Capabilities
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Spill barge Thomas N. George places dredge materials from the
Mississippi River to fill eroded areas near Lock 25 in
Winfield, Missouri. U.S. Army Corps of Engineers
St. Louis District officials used the Dredge Potter’s flexible
pipe assembly to move more than 100,000 cubic yards to
stabilize the overflow dike.
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Bearing the name, Thomas N.
George, a new spill barge joined the Potter
for its inaugural season this year.
Using the floating flexible pipe
allows the Dredge Potter more
material placement options than using a traditional rigid metal pipe which requires
left or right side-casting of the dredged material.
The flexible floating pipe allows
the dredged material to be placed independently of the dredge as it moves to
avoid fleeting areas and or for more versatility around well-used areas of the
river.
November was a busy month
While nearly finished at the mouth
of the Kaskaskia River, November 14, the Dredge Potter experienced a D-ring failure (a critical link in the suction
ladder lifting chains). When the D-ring failed the Dredge Potter’s suction ladder dropped and became stuck nearly vertical
under the dredge. The Potter’s crew
worked tirelessly and five days later the ladder was recovered and secured
without any additional damage.
Dredge Master Randy Jowers,
St. Louis District Service Base staff and Marine Design Center developed an
interim repair, and the Potter was back
to work status by November 22, just in time to face another crisis on the
river.
When engineers discovered
erosion along the overflow dike at Lock and Dam 25 in Winfield, Missouri, the
Dredge Potter and her crew answered
the call. With no contract or government dredges available, the Potter was willing and available to
assist with the emergency repairs before flooding could threaten the stability
of the dike. If flooding causes the dike to fail, barge traffic on the river
could come to a standstill.
With repairs to the ladder
rigging complete the Potter and her
crew immediately departed for Lock and Dam 25, November 22.
By November 23, the Potter had reached her destination. Upon
arrival her crew began the process of setting up the 2,400-foot flexible
pipeline. The flex pipe coupled with the spill barge gives the dredge team the
ability to reach farther and aim more precisely when placing material. Two days
later, the Potter was already placing
material into the scour hole below the Lock 25 spillway. 258,000 cubic yards of
dredge material was placed into the scour hole and in an adjacent stockpile.
"Without the flexible
dredge pipe and the spill barge Thomas N. George, our only other option would
have been dredging by mechanical means with a clamshell dredge," said Mike
Rodgers, project manager for the emergency repairs at Lock and Dam 25.
The clamshell method would
have moved roughly 2,000 cubic yards of material a day, with an estimated
timeline of nearly three months to complete. Employing the Thomas N. George and
flex pipe, the Dredge Potter team
moved more than 20,000 cubic yards a day, completing the work in about ten
days.
"With the flex pipe and
the Thomas N. George spill barge, we have a lot more options to place of
material," Rodgers said. "Without it, we wouldn't have
completed the permanent repair in time for the spring flood season."
Hardest working octogenarian on the river
For more than 80 years the Potter has remained true to her mission,
making navigation possible for towboats to move commodities up and down the
Mississippi.
St. Louis is the third
largest inland port by tonnage, and commercial navigation thrives on the St.
Louis District’s stretch of the river thanks in large part to the hard work of
the Potter crew.
Operating 24 hours a day, the
crew is organized into three watches, with two alternating watches while the
third is off duty. There is one First Mate, three Second Mates and four Deckhands
on watch at all times.
“If it were not for the
dedicated Potter crew and Service
Base staff, the Dredge Potter could
have easily been down for repairs for a month, which would have been disastrous
to maintaining the navigation channel and supporting the emergency scour repair
at Lock 25 spillway,” said Engle.
A typical dredging season in
St. Louis District runs from July to December, but can change based on river
conditions. As recently as the 2012-2013 dredging season, more than 8 million
cubic yards of sediment was dredged in a six month period to address low water
conditions.
