Page 356 - Peterson 85 Years and Going Strong

Left to right: Two of Buster’s original Quad D9s (No. 107 & 109) were used on the Oroville Dam project in 1964-65; Oman used a railroad system with automated railcar tippers to transport materials instead of a traditional fleet of scrapers and haul trucks.
Once the foundation was cleaned to an immac- ulate finish, Kiewit crews started filling in the canyon’s nooks and crannies with RCC. They also drilled and installed long steel tie rods deep into the bedrock as an additional down-anchor to hold the new concrete slabs in place. Layer by layer, they built up the main spillway in stages across its 250- foot width. The final layer was erosion-resistant, high-strength concrete, up to three feet thick, for a smooth and durable finish.
EMERGENCY SPILLWAY
During the emergency spillway’s first-ever use in February 2017, the hillside sustained large gouges which first-responders filled with bags of rock and riprap, glued in with slurry as a stopgap during the crisis. Once things settled down, Kiewit removed all those temporary fixes and dug down to bed- rock. Kiewit’s subcontractor, Drilltech, installed a new secant pile wall on the downstream perimeter for further protection. The underground wall con- sists of 600 individual 36-inch diameter piles built into bedrock up to 65 feet deep. It will prevent any erosion should use of the emergency spillway be required again.
2 “Oroville Dam”, Goodyear’s BIG magazine, July 1967: Vol 23, No 3, p3
Once the wall was complete, the soil was excavated to rock and replaced with a minimum of ten feet of RCC to make it permanent. “Crews placed RCC on the emergency spillway in a stair-step forma- tion to direct water flow,” says Nipar. “They did not top it with construction grade concrete because it’s just for emergency use.” Instead they poured a 10- ft thick splash-pad, both above and below the un- derground stabilizing wall, which now looks like a giant concrete amphitheater.
TECHNOLOGIES OF THE DAY
Like Kiewit in 2017, Oman Dam Constructors used progressive methods and equipment to get them over the finish line. According to Rodney Mims, Oman’s project manager at Oroville in the 1960s, “This job was pre-planned, and carried out just as we originally planned it. Looking back, I don’t see any better method that could have been employed.”2 They moved a total of 80 million cubic yards of material with a final price tag of $439 mil- lion. The job was considered the most highly au- tomated of its kind in the 1960s, involving an as- tounding volume and variety of equipment, much of it specially designed. “Such a project would
354 | PETERSON: 85 YEARS AND GOING STRONG