Oroville – The second and final phase of reconstruction continues at the Oroville Dam spillways.
This year, contractor Kiewit Infrastructure West Co. is rebuilding the top 730-foot portion of the main spillway and using structural concrete to rebuild the walls and resurface the chute in the middle.
A flight over the location last week during a break in Butte County Sheriff’s Office helicopter training exercise, showed that much original concrete at the top of the chute has been removed, along with the walls.
The exposed surface will next be prepared for installation of a drain system and leveling concrete. The structural concrete surface will be applied over that foundation, and new structural concrete walls will be built there.
Start your day with the news you need from the Bay Area and beyond. Sign up for our ew Morning Report weekday newsletter .
In the center, a top layer of the roller-compacted concrete that was placed last year has been removed, and the RCC walls are being removed. Next a drainage system will be added, along with a new structural concrete surface and walls.
The dentates or energy dissipaters at the bottom of the spillway are also being resurfaced.
At the emergency spillway, a roller-compacted concrete “splash pad” is under construction. It is designed to reduce erosion uphill erosion toward the weir like that which prompted evacuation orders in February 2017, should the emergency spillway be used again.
Oroville Dam: FEMA still deciding whether to reimburse DWR for major repairs
Oroville Dam without DWR? It’s a possibility
It’s been done in two parts, with the northern half reported to be about 65 percent complete on May 9. During last week’s flight it looked to be nearly complete. That will allow work to being on the southern half.
The weir at the top of the emergency spillway is also to be buttressed.
The state Department of Water Resources plans to finish the work on the main chute by Nov. 1, although work on the emergency spillway will last into 2019.