California Department of Water Resources / Dale Kolke
Feb. 15, 2017. Days after failure, 100,000-cubic-feet-per-second…
Feb. 15, 2017. Days after failure, 100,000-cubic-feet-per-second outflow continues to erode the lower chute. About 1,400 feet of the lower concrete chute was destroyed and 1.6 million cubic yards of soil and rock eroded, leaving a 100-foot hole across the spillway’s full width.
California Department of Water Resources / Florence Low
March 3, 2017. Workers inspect damage to the middle part of the …
March 3, 2017. Workers inspect damage to the middle part of the chute. Roller-compacted concrete will be used to fill the enormous hole.
California Department of Water Resources / Dale Kolke
July 10, 2017. Rock in the hole’s bottom was cleaned with wate…
July 10, 2017. Rock in the hole’s bottom was cleaned with water and a high-pressure vacuum in preparation for roller-compacted concrete (RCC) placement. Grout-enriched, vibratable RCC was used to ensure a tight bond with the rock foundation and penetration into nooks and crannies.
California Department of Water Resources / Florence Low
July 26, 2017. Leveling concrete (not RCC) was placed between st…
July 26, 2017. Leveling concrete (not RCC) was placed between stay-forms on the lower chute’s steep slope.
California Department of Water Resources / Kelly M. Grow
July 28, 2017. RCC was placed in 15-inch lifts and compacted to …
July 28, 2017. RCC was placed in 15-inch lifts and compacted to 12 inches to fill eroded areas between the spillway’s lower and upper sections. In general, there were no cold joints. Much of the compaction was accomplished with a vibrating pad on an excavator arm.
California Department of Water Resources / Ken James
Oct. 25, 2017. Water and compressed air removes loose rocks from…
Oct. 25, 2017. Water and compressed air removes loose rocks from the surface of the roller-compacted concrete (RCC) between the upper and lower chute in preparation for a layer of enriched (higher cementitious content) RCC as the temporary wearing surface.
California Department of Water Resources / Ken James
Oct. 30, 2017. With two days left to complete the 2017 work, cre…
Oct. 30, 2017. With two days left to complete the 2017 work, crews place the surface layer of enriched (more cement) roller-compacted concrete between the upper and lower chutes. The lower chute was replaced with structural concrete in 2017; the upper chute was undamaged but will be replaced in 2018. The RCC section will be overlayed with structural concrete.
California Department of Water Resources / Zack Cunningham
May 8, 2018. With 2018 construction season underway, Ferma Corp….
May 8, 2018. With 2018 construction season underway, Ferma Corp. excavators begin removing the temporary RCC sidewalls from the middle chute. Permanent concrete walls will be built in their place later this year.
On Feb. 7, 2017, after several very large rainfalls, the Oroville Dam’s 179-foot-wide flood control outlet (FCO) spillway chute was releasing water to control the Lake Oroville reservoir level when it suffered a catastrophic failure.
Over the next nine months, the California Department of Water Resources worked towards meeting its Nov. 1, 2017 goal of replacing the spillway’s lower chute and sections of the upper chute and placing roller-compacted concrete (RCC) in the middle erosion area so the flood control spillway could handle flows up to 100,000 cubic feet per second (cfs). ALthough, as it turned out, the spillway wasn’t used during the 2017-2018 flood season. Part of the 2017 work was temporary, to be completed or redone in 2018. The 2018 phase of the project kicked off on May 8.
An important aspect of the work in 2017 was using RCC to fill the hole, as the temporary chute surface in the middle of the spillway, and to temporarily rebuild the sidewalls in the middle part of the chute. About 350,000 cubic yards of RCC was placed. Much of the aggregate was eroded material dredged from the Feather River.
Bill Palmer is former editor-at-large of Hanley Wood’s Commercial Construction Group, which includes digital and print versions of Concrete Construction, Concrete Surfaces, The Concrete Producer, Public Works, and Masonry Construction. Previously, he worked for the American Concrete Institute for 10 years as engineering editor and director of educational programs and was the executive director of the American Society of Concrete Contractors (ASCC) and of The Masonry Society. He has been the editor in chief of Concrete Construction for 16 years. Bill is a Fellow of the American Concrete Institute and is a licensed professional engineer in Michigan and Colorado. He lives in Lyons, Colorado. Follow on twitter @WmPalmer.
