Department of Water Resources Project Manager Randy Fessler gave an update on the construction currently being done at the Oroville Dam Spillways. Fessler works in the Emergency Management Department and has been at the site since day one in February.
Fessler gave an overview of the major project elements along with the construction progress update of the two main projects, the main spillway and the emergency spillway.
Noting that the main spillway is a huge project, Fessler explained there will be a complete replacement of the original spillway chute in the three sections, upper, middle and lower to be completed in two phases in 2017/2018.
The emergency spillway is three independent projects to upgrade and add on to the existing structure also in two phases in 2017/2018. The three projects are an underground cutoff wall, concrete buttress structure and roller compacted concrete (RCC) erosion protection.
Current pictures of the spillway were shown to the Council and staff to show how the damage is being filled in on the main spillway with concrete above and below the main section. Fessler explained that the upper 750 feet will remain intact this season and will be replaced next season as there is not enough time to get that section replaced now before winter.
The structural concrete walls to the floor slabs are now being done.
"There has been a lot of work in the last two weeks to close up the middle section. There will be up to 150 feet deep being filled in with roller compacted concrete in the next week or two," Fessler explained telling Council compacted concrete is being brought in continuously by trucks.
He explained using the RCC means doing one section at a time which bonds better than what was there before.
"It takes two days to form, pour and remove sections," he stated.
As for the Emergency Spillway, drilling is being done down to the bedrock and work is moving at a fast pace. This work will continue past November 1 and will be completed in December.
"Workers will finish this section by the end of the year," he stated.
Questions from Council and City Attorney Tony Galyean were answered by Fessler regarding water levels, the Hyatt Power Plant and the roller compacted concrete being used.
Fessler explained the RCC is almost like asphalt but it dries hard. He also stated a new truck comes every five minutes with the RCC which hasn't been used a lot except for dams over the last 30-40 years from top to bottom.
"This is 100 percent more economical and faster. You couldn't get 10 percent of the project done with conventional concrete. This will be a huge case setting for dams everywhere," he stated.
When asked about the gates and if they would be replaced, Fessler stated the gates will remain in place noting they are being evaluated now.
"There is no indication of any disrepair or damage to be a problem," he said.
There are over 600 workers on site each day and a total of 496,000 hours have been logged so far as of September 29, 2017.