Diver Dave Cleary surfaces after guiding another sheet piling in place during repair operations at the Hiram M. Chittenden Locks.
By Anne-Marije Rook 02/07/2012
From the Ballard News-Tribune
The Ballard locks will be closed to all pedestrian traffic Feb. 7 and Feb. 8th to all pedestrian traffic as the U.S. Army Corps of Engineers is repairing a scour near the small lock wall. Vessel traffic will also be halted from 8 a.m. to 6 p.m.
The 95-year old Hiram M. Chittenden Locks are showing signs of water wear and tear, and repair work is needed.
Water has caused erosion along a portion of the small lock wall creating a scour. U.S. Army Corps of Engineers official say the lock is safe and there is no immediate danger of failure, but the repair is needed to maintain the safe waterway and stop further erosion. “There have been scour problems documented in a nearby area for 30 years. The first major repair was done in 1985 to the apron,” said Marian Valentine, a hydraulic engineer in charge of operations and maintenance of the facility, in a statement. “Water is very destructive so we actively monitor the locks and make interim repairs where necessary.”
A 2009 sonar survey detected an elongated scour hole and during a subsequent dive inspection, a void was noticed under the small lock foundation.
To repair the monolith, the Corps contracted Redside Construction, Port Gamble, Wash., for $1.3 million to drive sheet piles adjacent to the wall. These sheet piles will act as armor, to prevent future erosion, and as forms so concrete can be pumped in to fill the void. As part of the contract, riprap and quarry spalls will be placed in areas where channel scour occurred.
To minimize aquatic ecosystem harm, the Corps worked with state and federal agencies and scheduled work to coincide with U.S. Fish and Wildlife Service time restrictions. The Corps also prepared a Biological Evaluation in accordance with the Endangered Species Act to assure full compliance, according to Project Manager Joshua Jackson.
The work is expected to take 60 days to complete but the locks will only be closed a couple of days.