Locks 27 main 1200-foot chamber to close for maintenance

August 21, Granite City, Ill. – The U.S. Army Corps of Engineers announced today that they will close the main 1200-foot chamber of Locks 27, near Granite City for maintenance, Friday, Aug. 22. The closure is slated to last approximately one week.

Repairs are to be performed on the diagonal, or cross braces on the miter gates at the lower end of the main lock chamber. The miter gates are the huge gates that open and shut like giant doors at the south end of the concrete lock chamber.

Repairs are made necessary by deterioration of the tensioning rods that adjust the diagonal supports. Divers from the Rock Island District recently determined that four of 16 such threaded rods have broken and Corps structural engineers have determined that repairs should be made as soon as possible.

Timing of the repairs was carefully coordinated with navigation industry interests and has been based on three factors and:

• Time to obtaining the proper replacement
   parts
• Elevation of the water, both in the river
   and the ground on the land side of the
   chamber
• Sufficient time to eliminate the queue of
   waiting tows that built up after the river
   channel silted in, necessitating emergency
   dredging north of Winfield, Mo.

The water level issue came into play in 2005 when similar work was accomplished on the tops of the miter gate leafs. If water levels are too high in the river and the adjacent ground, there is danger that the pressure will distort the concrete lock walls.

Structural engineers indicate that the diagonal braces keep each of the 70 by 61- foot, 206- ton gate leaf’s square and in plumb. If the braces fail completely there is danger that the gates will stop functioning. This would require a lengthy closure to replace or repair the gates just as the fall harvest of grain commodities was being readied to go to markets overseas.

While the main chamber, which can allow a 15-barge tow to be locked through in a single trip is closed, the auxiliary 600-foot chamber will remain in operation. Locking 15-barge tows through that short chamber requires that they but “cut” into two sections and locked one section at a time. A helper boat will be on scene throughout repairs to speed that process.

All commercial navigation traffic for the Mississippi River and Missouri and Illinois Rivers must pass through Locks 27 at the foot of the Chain of Rocks canal coming from or proceeding into the St. Louis Harbor. More than 67 million tons of cargo carried in 8,681 barge tows passed through Locks 27 in 2007.