Problem:
A 60+ year old gate on a Mississippi River lock is in need of major repair. A temporary cofferdam must be completely water tight while work is completed, or the full force of the Mississippi River could be released through the lock and flood control structure.
Solution:
A one piece 40 mil PVC liner panel from Environmental Protection, Inc.
Lock 24 on the Mississippi River is located about 60 miles north of St. Louis, MO at Clarksville. The 600 foot long, 110 foot wide lock opened for service in 1940. The lock and flood control structure was designed for the future construction of a second complete lock, should future barge traffic warrant it. Only the upstream gate of the future second lock was installed during initial construction. The unused second lock gate was in need of maintenance and repair.
An existing rock dam protects the gate from the ravages of the Mississippi, but the U.S. Army Corps of Engineers decided to take no chances while the repair work was being done. To minimize any seepage through the damn, the Corps required a PVC liner over the face of the damn and attached to the side walls of the lock entrance.
Midwest Foundation Corporation had the contract to repair the gate and other major maintenance work at Lock 24. The CorpsLock 24 of Engineers specification called for a 40 mil PVC geomembrane liner to be placed on the face of the rock dam to prevent any seepage of water which might destabilize the dam while the gate is out of service. Midwest used a one piece, 81’ x 120’ panel of 40 mil PVC from EPI for this installation.
The panel was unfolded and attached with a 2x4 batten to a 100’ long I-beam. The liner was then lashed to the beam for transporting from the staging area to the 110’ wide lock.
The barge, crane, beam and liner were moved into position at the upstream side of the rock dam. The upper 120’ edge of the liner was anchored to a concrete sidewalk along the top of the dam. The panel was then positioned by lowering the beam along the face of the dam under-water until the full width of the panel was unfolded in place. Each end of the liner was then attached with batten to the walls of the Lock on each side to secure the installation.
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