Mike Scronce, project superintendent for Fisher Industries, the general contractor charged with finishing the I-580 extension from Mount Rose Highway to Bowers Mansion, says he's never tackled a more challenging job in his 16 years of experience than completing the temporary fill for the Galena Creek Bridge.
Fisher began work in March on the fill 390,000 cubic yards of compacted dirt atop a 44-foot-wide, 22-foot-high and 400-foot-long concrete arch protecting Galena Creek.
The fill 120 feet tall, 400 feet wide at its base and 220 feet wide at the top allows bridge contractor CC
Meyers of Rancho Cordova, Calif., to begin erecting the temporary support structures needed to build the 1,790-foot bridge.
"That is a lot of dirt," Scronce says. "I've never done any fill job so tall or steep. Everyone was very skeptical in the beginning, saying it couldn't be done, it wouldn't work. We proved that it did work and can be done."
Fisher Industries Project Manager Norm Bessler developed a system to keep the fill in place as it rose some 12 stories above the valley floor.
The key pieces are four-foot tall "barrier rail" forms something like highway lane dividers with vertical backsides. Workers laid heavy-duty reinforcing fabric up the vertical side, bundled the fabric at the top, and spread it over the compacted dirt once it reached the top of the rail. Loaders and bulldozers spread out the material that was delivered by a conveyor belt. Caterpillar 825 compactors, which have huge knobbed metal wheels, compacted the fill.
Steel mesh mats were installed at the edges so that the fill could retain stability at great height and hold the tremendous weight of the loads passing across it.
Each of the 12,000-pound rail forms was engineered with cable railing on top that doubled as fall protection, allowing workers to avoid using safety harnesses.
"We are happy to have that part done, and we are looking forward to the CC Meyers team constructing the bridge," says company president Tommy Fisher. "It's been a long time coming."
An average of 45 men, with 10 to 15 working through the night, labored from March 20 through June 22.
"They have worked a lot of long hours and were working seven days a week," Scronce says. "But now we can take the work forces that were concentrated here and spread them out and get the rest of it done."
Completing the highway project still requires massive effort from Fisher Industries. Crews recently completed two of eight pours on the 700-foot Steamboat Bridge but still need to pour more than 6,500 yards of concrete. And there are eight time-intensive mechnically-stabilized-earth retaining walls still to
be built.
Bringing the roadway to grade throughout the project requires 4 million cubic yards of excavation and grading, mostly from the north to the south.
The challenges to the fill plan aren't over, either, because the dirt and massive 30-inch-thick concrete arch has to be removed. And how will it all come out?
"Very carefully," Scronce says.
The removal plan involves using conveyer belts and trucks to haul out the dirt, which will be used for grading at the south end of the job.
"Pulling the metal straps out, we will have to have a couple of excavators with shears on them and a magnet getting it wadded up and pulling it out as we get the dirt loaded," Scronce says. "It will be very challenging.
At that point, the bridge will be done, and it will be the big push to get the job completed. There is going to be a lot of pressure again."
But at least now the Galena Creek Bridge, which caused the original contractor, Edward Kraemer and Sons Inc. of Plain, Wis., to leave the job over safety concerns, can be constructed after a more than two-year delay.
Scronce won't be relaxing any time soon.
"When the first car drives across this thing, and I have a cold Budweiser in my hand, that is when I will feel good," he says. "Until then it is push as hard as we can as fast as we can."
The I-580 extension is expected to be completed by 2011.
