Crack Forces Dewatering Of Pickwick Main Chamber

The main chamber at Pickwick Locks and Dam, Tennessee River Mile 206.7, is closed because of a crack in the bottom of a gate that is allowing water to flow through it.

A maintenance crew doing an inspection in April noticed a loud humming and significant vibration during operation of the lower miter gates, said Jason N. Johnson, chief of the maintenance section of the Nashville Engineer District’s Technical Support Branch.

Because of a previous issue, it was initially assumed the noise and vibration were due to leakage of water through the rubber seal at the bottom of the gate leaves. A dive inspection was scheduled for May to verify the assumption or to uncover the cause.

On May 25, the diver inspection found damage to the bottom gate pan of the land leaf of the lower miter gate, Johnson said. The repair will require dewatering the 1,000- by 110-foot lock chamber to inspect the damaged section in the dry and determine how best to repair it, he said. Meanwhile, traffic is being passed in the 600- by 110-foot auxiliary lock.

Randy King, lock and dam equipment mechanic supervisor for the Nashville Engineer District, said the crack in the gate pan is 6 to 8 feet long and 1 inch wide in one section. 

“As far as knowing how bad it is, we won’t know that until we can dewater it,” he said.

The crack goes all the way through the bottom pan, he said.

The cause of the crack is undetermined.

King hoped to have a conference call within the next few days to talk about scheduling the dewatering, but no timeline was immediately available.

The closure of the main chamber has the largest effect on tows that are 600-1,000 feet long, which must now double-lock through the auxiliary chamber, King said. Although no queue has been typical, at times there has been a wait up to a few hours, he said.