ORD FERRY — A renovation project at the Ord Ferry Bridge, that has been in the works for more than a decade, is at least partially taking place 30 feet below the surface of the Sacramento River.
In 2002 Butte County began preliminary work on a plan to do a seismic retrofit on the Ord Ferry Bridge, which spans the Sacramento River near the community of Glenn.
After a decade of preparation, much of which involved navigating the complex environmental requirements imposed by various agencies, construction work began in June.
“Sometimes it is a miracle anything gets done at all,” said Raymond Cooper, Butte County Department of Public Works project manager for the bridge.
If getting through the various regulations was a challenge, the project itself is at least as complicated.
A major part of the project involves enlarging the footings that support the massive pillars that hold up the bridge. To do that the workers must labor in a three-story deep hole created in the river.
Cooper said to create a “hole” in flowing river pieces of shaped steel are pounded and shaken down the bedrock around each of the massive bridge pillars. The metal slats are joined for a coffer dam around each of the pillars.
Then the rock, trees, mud and whatever other material is inside the dam is dug out.
When the mountains of debris, rock and mud have been removed down the original footing, a concrete sealer is pumped to the bottom, according to Cooper.
With the bottom sealed, explained Cooper, the water is pumped out from inside the coffer dams. The water goes into settling tanks where the sediment is removed. The water is then “treated” before it is released back into the river.
Crews with jackhammers work in the 30-foot deep pits to cut down to the re-bar in the old footings. Additional steel reinforcing bars are attached to the original and concrete is added to enlarge the footings.
Because the work is taking place on, above, or below the surface level of the river, everybody involved in the project, including visitors, must wear hard-hats, reflective vests, and life preservers before setting foot on the construction site.
Terry Edwards, county DPW’s “resident engineer” for the project, said after the footings are prepared a cylindrical steel sheeting is welded around each pillar. A layer of grout is pumped between the concrete pillar and the sheeting, which prevents water from getting to the pillar.
The process is repeated at every pillar, and by last week four pillars were in some stage of the process.
While expanding, reinforcing and armoring the pillars continued, other work is taking place inside the concrete road-bed structure of the bridge.
The overall goal of the project is to improve the earthquake safety of the bridge. Drivers going over the bridge can see the three sets of joints that connect the three segments of the bridge. What the drivers can’t see are “bearing pads” beneath the roadway that allow the bridge to move in the event of a quake said Edwards.
He explained that workers go inside the concrete structure through access ports on the under side and jackhammer away the supports under the old bearing pads.
Using what amounts to massive jacks, the segments of the road are individually lifted a few inches to allow the removal of the old bearing pads and their replacement with new pads. Then the bridge is allowed to settle into place on the new pads.
Edwards said the process will go on with little interruption of the traffic flowing over the bridge.
Cooper said while a crew of about 25 people is working 10 to 12 hours a day, six days a week, the project won’t be completed until probably early 2014.
The current work will need to be wrapped up, with the piers under the bridge and the coffer dams removed before the winter rains raise the river level.
Cooper said the plan is to finish this season’s work on Butte County side of the river and to resume all of the same steps coming from the Glenn County side next year.
The total project is supposed to cost just under $9.1 million by the time it is finished. All of the funding is coming from state and federal sources.
The main contractor is Golden State Bridge, Martinez.
Staff writer Roger H. Aylworth can be reached at 896-7762 or at [email protected], or at @RogerAylworth on Twitter.
