We replaced the miter gates for the USACE at Lock 27 near Granite City, Illinois. To replace the miter gates in the main lock chamber, lock bulkheads had to be installed before the chamber could be dewatered. A total of 11 bulkheads were installed by floating plant on the upstream end of the lock, and nine bulkheads on the downstream end. Culvert valve bulkheads and stub recess bulkheads were also set. Dewatering of the chamber consisted of using a number of 10-inch submersible pumps. The overall dewatering/rewatering operations continued throughout the project. The lock was dewatered a total of three times: once at the initial start, next after removal of the old miter gates, and again after installation of new miter gates. 

Installation of the miter gates required the use of a floating 4600 Series 3 ringer crane. The first stage was removing the existing 430,000-pound miter gates. After those gates were moved, the concrete sill and quoin block were inspected and the pintle ball and anchorage links were replaced. The new 550,000-pound miter gates were then installed and adjustments were made to the miter gate alignment. This work included adjustment of the bulb seals, prestressing of the gate diagonals, and adjustment of the contact blocks.