The U.S. Army Corps of Engineers is in the midst of installing what are called bulkhead slots at Lock and Dam 15, a preparatory step for what is a relatively rare occurrence: The draining of the lock to conduct more extensive inspections and maintenance.
No plans are being made yet to dewater the lock. That will require funding that is not yet available, Corps officials say. However, over the past five or six years, the Rock Island district of the Corps has been installing bulkhead slots at the dozen locks along the Mississippi River that fall under its jurisdiction so that when funding is available, they'll be ready.
"In a nutshell, it's basically for routine maintenance and inspection," said Matt Coffelt, a project manager at the Corps' Rock Island office.
The slots accommodate bulkheads, large wall-like structures that typically are 110 feet long and weigh about 80,000 pounds. The bulkheads hold back the water, allowing the chamber to be drained and work to be done. Last year, the slots were installed at Lock and Dam 14 in LeClaire.
Dewatering is rare. The last time it happened at Lock and Dam 15 was in 1996. However, some locks in the area have been dewatered recently. Last year, the lock near Fulton, Illinois, was dewatered, removing 10 million gallons of water.
Currently, the lock near New Boston, Illinois, has had the water drained. The contractor on the project there, as well as at Lock and Dam 15, is J.F. Brennan Co. of LaCrosse, Wisconsin.
The lock and dam system was built in the 1930s, Corps officials stress, so ongoing maintenance is important.
Major work to install the slots at the lock between Rock Island and Davenport began in mid-December. Slots are now being installed in the main chamber, and later this spring and summer, they'll go in the auxiliary chamber.
The cost of this project is $6.7 million, said Allen Marshall, a Corps spokesman.
The winter months are slow times for the locks, so that's why the work is being done in the main chamber now. By fall, Corps officials say, they expect the last of the slots to be installed on all the Mississippi locks that fall under its jurisdiction.