LAKE OROVILLE SPILLWAYS CONSTRUCTION: Update for June 6 (with video and photos)

A loader with a sweeper attachment cleans small rock and debris near one of the underdrain trenches on the middle chute of the Lake Oroville main spillway where roller-compacted concrete recently was poured. Photo taken in Butte County, California on June 4, 2018.
Kelly M. Grow/ CA DWR

From the Department of Water Resources:

Today the Department of Water Resources (DWR) provided an update on construction-related activities for the Lake Oroville Spillways Emergency Recovery Project.

Construction on the Main Spillway

  • Controlled blasting demolition of the original 730 feet of the upper chute is complete. Crews are preparing the foundation for placement of structural concrete slabs and walls.
  • In the middle chute, foundation prep is 34 percent complete and crews are preparing for the installation of sub-drains and slab anchors in advance of placing permanent structural concrete slabs and walls later this summer.
  • Work continues on the energy dissipaters, or dentates, at the bottom of the main spillway. The dentates are being hydro-blasted to prepare for the placement of a new layer of structural concrete reinforced with epoxy-coated steel dowels.
  • DWR is again using November 1 as a milestone to complete major construction work and placement of all concrete on the main spillway. Additional work, including dry finishing and curing of concrete, joint sealing, connecting drainage systems, backfilling side walls, and site clean-up on the main spillway will continue after November 1.

Construction on the Emergency Spillway

  • Construction of the northern half of the roller-compacted concrete splashpad is 80 percent complete.
  • Crews are 40 percent complete with foundation prep at the southern half of the splashpad site in advance of RCC placement.
  • Work at the emergency spillway site is not dependent on the November 1 milestone and will continue throughout 2018.

Additional Updates

  • The free access program for day use and boat launching at the Lake Oroville State Recreation Area continues tomorrow and Friday, June 7 and 8. Additional free access days include July 5-6, August 2-3 and September 6-7. Free access applies to day use and boat launching only.
  • Lake levels are currently at 818 feet . DWR anticipates some water to pass through the gates until the lake level drops below 813 feet. Crews have put in place a water containment system to collect any water that passes through, which will have no impact on construction.
  • DWR met with the U.S. Army Corps of Engineers last week to begin coordinating the update of the 2018-2019 flood control season operations plan for Lake Oroville. The plan will guide reservoir operations through the upcoming flood control season and will follow a similar approach to the 2017-2018 operations plan.
  • The independent Board of Consultants met with DWR for the 18th time on May 29 and 30.
  • Crews continue work to resurface a structural concrete slab that was placed last year that had a poor surface finish and did not meet DWR’s quality control standards. When commenting on the work to remove the top layer of concrete on this slab, the independent Board of Consultants stated, “the removal of the erosion resistant concrete has turned out to be much more difficult than expected…this information provides empirical evidence that the chute concrete has superior erosion resistant properties.”

The latest video from DWR …

(dated May 31st): Crews lay roller-compacted concrete (RCC) for the spillway splashpad and excavators break rock to prepare for the placement of structural concrete walls for the spillway’s new upper chute. Workers install under drains within the middle chute and drilling rigs bore a series of holes in the RCC to prepare for slab anchors that will be placed in the middle chute. Crews also break concrete on the lower transition slab to prepare for the placement of structural concrete.

Photos from Lake Oroville …

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