Round-the-clock work on Oroville repairs

The Department of Water Resources is working around the clock to keep its promise of meeting the Nov. 1 deadline for repairing the dilapidated spillway at Oroville Dam.

In a media conference call Wednesday, that message was reiterated, along with an update on the 20-hour-a-day construction work.

DWR Chief of Engineering Jeanne Kuttel said the demolition of the lower chute is essentially complete.

“Drilling and controlled blasting is still

ongoing and should be completed within the next three weeks,” Kuttel said.

The lower chute is the 1,400-foot portion of the spillway that releases water into the Feather River. It sustained significant erosion.

The 1,000-foot upper chute leading to the floodgates, Kuttel said, will be patched and reinforced and will remain intact this year. It will be replaced in the 2018 season, she said.

“We’re now preparing for the main spillway foundation in early July,” Kuttel said, saying this is a milestone for the project.

Jeff Petersen, project director for Kiewit Infrastructure West Co., said crews are still prepping the foundation, but production will ramp up over the next few weeks in anticipation of laying concrete.

The two types of concrete that will be used are structural (used in sidewalks) and roller-compacted concrete. RCC provides the foundation for the concrete and fills major holes and canyons that were washed out, Petersen said. RCC production will start after the Fourth of July weekend and structural concrete will start shortly after – 800,000 cubic yards will be used for both spillways, Petersen said, and could fill 227 Olympic-sized swimming pools. Also reported during the briefing:

The Lake Oroville elevation was 816.03 feet, as of 4 p.m. Wednesday. Erin Mellon, communications manager for the project, said lake levels haven’t changed much, and officials aren’t worried about having enough room in the reservoir for the snow melt, despite the tripledigit temperatures.

“We certainly are monitoring the snowpack,” Mellon said, “and it’s coming down not nearly as quickly

Rrosenbaum@appealdemocrat.com Kelly M. Grow/ California Department of Water Resources A controlled blast breaks up concrete, rock and dirt on the lower chute of the Lake Oroville flood control spillway on June 16.