California
Related: About this forumDamage to Oroville's main spillway 'was an accident waiting to happen'
The badly damaged main concrete spillway at Oroville Dam was pounded by massive volumes of stormwater this month, but its failures occurred well short of the maximum flow that engineers designed the system to handle.
The spillway began breaking apart when its gates were opened Feb. 7, allowing 55,000 cubic feet of water per second to roar down the slope. That was only 18% of the 300,000 cubic feet of water the channel was designed to carry per second, one of the factors that raise significant questions about its design integrity, engineering experts said. Eventually, the gash that opened up had grown to 500 feet in length and dug a hole 45 feet deep in the earth.
Weakness in the aged concrete, inadequate repairs of cracks and instability in the ground under the spillway caused large pieces of concrete to break apart and tumble downhill, said Robert Bea, a retired civil engineering professor at UC Berkeley who led one of the investigations into the failures of the New Orleans levee system in Hurricane Katrinas wake.
The failures in the concrete spillway will be investigated for a long time. But some of the nations top civil engineers are already pointing to some likely suspects: design flaws, misunderstood geology and poor maintenance over the years.
http://www.latimes.com/local/california/la-me-ln-oroville-spillway-damage-20170220-story.html
global1
(25,242 posts)I understand that large amounts of rain is expected in the area. Will there be a need to issue new evacuation orders?
Brother Buzz
(36,416 posts)I've been following all the daily briefing, and it appears the have a handle on the mess. A ton of work is being done on multiple fronts, and plans to repair are already underway. They believe the primary spillway will last through the wet season, then the rebuild can start in earnest.
global1
(25,242 posts)but I can't imagine the stress that the people that live in the pathway are in. I would be beside myself given the predictions of the rain they are expecting. I don't know if I could sleep peacefully knowing that - albeit - a slim possibility that it might give way and swamp them. I guess I would have all my stuff ready in case another evacuation was called for. However, with the rain that they are expecting - I can't imagine the chaos that another evacuation would create.
Brother Buzz
(36,416 posts)because they are stressed to the max. But everyone has had days (not hours) to plan their evacuation if things go south, plus there will be plenty of warning, unlike the first one.
The dam is sound (heck, it hasn't played a roll in this mess except stand there and hold back water)
The emergency spillway is structurally sound, and they appear to have an upper hand on preparing the outflow
The lake level has been dropped to bank a storm reserve.
The primary spillway, albeit compromised, still functions.
Keen minds are working 24/7 on every contingency.
All that being said, I believe the people living below the dam won't stop stressing until the dry season begins.
proverbialwisdom
(4,959 posts)Oroville Dam Workers Fired for Posting Spillway Photos to Social Media
Posted 4:07 PM, February 19, 2017, by FOX40 Web Desk
OROVILLE Five Oroville Dam workers were fired for posting spillway photographs to social media.
A spokesperson for the California Department of Water Resources told KRON that a number of employees working under the Folsom contracting company Syblon Reid violated the terms of their contract by posting the pictures.
A Syblon Reid contractor had forbidden a spillway team from capturing any activities at the dam and sharing the footage via social media. The contracting company has enforced this no social media/no photos policy at all of their construction sites.
More: http://kron4.com/2017/02/18/5-oroville-dam-workers-fired-after-posting-pictures-on-social-media/