"10 Year" storm for California - Spillway Collapse Update

D’Oh… factor of 60 is outside engineering tolerances… yes, it’s cfs … thanks Niko.

It’s staggering volume of water 8O You’re excused :lol:

Who in the world approved an earthen emergency spillway. Even I know what moving water does to dirt?? 8O

So, the main spillway, someone wasn’t inspecting it regularly to catch the reason for the erosion to occur?

Busy armchair engineer here, 100% guaranteed pure speculation on my part :lol:

According to this article the exact issue came up 12 years ago when the dam was re-licensed. When the various officials have been asked on TV about this 2005 report it’s been like watching the three monkeys, no one admits to having seen it.

Looking at the pictures, and diagrams, and the DWR’s panic about erosion it appears to me that the emergency spillway wall doesn’t have anything like the kind of foundation that I would expect for a “mini-dam”.

So, the main spillway, someone wasn't inspecting it regularly to catch the reason for the erosion to occur?

They fixed some cracks in that area (apparently with some kind of grout/caulk) a few years ago, and inspected it remotely a couple of years ago. Talking to my neighbor this morning we agreed that neither of us had seen any sign of rebar in the concrete floor of the spillway. With broken concrete like this wouldn’t you expect to see the rebar?

I think the erosion problem with the emergency spillway is actually at the other end, nearest the normal spillway. There is a section of erosion that worked it’s way back under the emergency spillway and caused the evacuation order. While a failure at the other end of the emergency spillway would have been a problem, the amount of water at the point near the parking lot would not have been 30’ tall. So far I have not heard any reports on how they plan to repair the portion of the erosion under the emergency spillway. I fear the storms expected Wed/Thu will make matters much worse as the lake level rises and puts more pressure on the spillway.

Agreed. They’ve been dumping a lot of rock+slurry at the normal spillway end. But there are some holes that appear to be very deep in various places. Hopefully they can take the water level low enough that the coming storm won’t be an issue.

I can’t find the quote now but a water & power guy said that a small flow of water can cause more erosion than a really gully washer :-k

Remotely? 8O 8O

Heck yeah, there would be rebar all over the place, especially since the rebar should either be tied or welded together at each junction.

I’m no dam expert, ha, but I’ve seen a few in my day, and I would expect a wider spillway on such a large lake.

Wonder if the concrete was even tested as it was poured back then, doubtful. Then did someone decide to add more water to the mix as it was being poured, and weakened it. Ugh, Government at work always give me heartburn.

Big rain coming. Atmospheric river forecast for Monday, targeted right at the Oroville dam area (yellow arrow).

8O 8O 8O

Alltime low baro today: 29.14 in (986.8 mb) and still falling. No wonder it was so windy. A lot of trees and powerlines down throughout the CWA.

Southwest is cancelling flights in the L.A. area and the NWS has suggested taking the afternoon off so they are getting nervous down south.

Yup, looks like it’s SoCal’s turn in the barrel. BTW, the following link also shows video of them dumping a lot of rock below the emergency spillway at Oroville Dam.

[size=83]Reports: Evacuations ordered in Southern California as major storm brings flood threat

One of the biggest storms in years is bombarding Southern California with heavy rain and gusty winds and will continue to slam the region into Saturday.

The worst conditions are expected from Los Angeles through Santa Barbara, California with heavy rain causing mudslides and significant travel delays. Evacuation orders have already been issued for some communities due to the high threat of mudslides.

Those traveling around Los Angeles for the Friday evening commute will likely face significant travel delays due to the rain. Some roads will potentially become impassable because of flooding.

Most flights out of John Wayne Airport in Orange County have been canceled today, including all Southwest and American flights.

Due to heavy rain and wind, there is a Traffic Management Program in effect for traffic arriving at Los Angeles International Airpot (LAX). According to www.faa.gov, some arriving flights are being delayed an average of 1 hour and 17 minutes.

There have been more than 900 flight delays and 400 flight cancellations at airports across California today, according to FlightStats.

[/size]

http://www.accuweather.com/en/weather-news/reports-evacuations-ordered-in-southern-california-as-major-storm-brings-flood-threat/70000891

LA rain is now trending on Twitter: https://twitter.com/hashtag/LARain?src=tren&data_id=tweet%3A832717273672462336

Flash flood warnings are in effect for Ventura, Los Angeles, Kern, and Santa Barbara counties.

Flight delays are now up to 129 minutes at LAX due to wind.

Egads! Just saw this on NWS Sacramento Twitter feed:

[size=83]Today's storm is impacting all of #California. But the next one will be bigger and more impactful for #NorCal early next week #CAStorm #cawx[/size]

https://twitter.com/NWSSacramento

Yeah, Monday will be our day 8O

We’ll be getting some of that down here too. Forecast for Monday:

Washington’s Birthday
Rain. The rain could be heavy at times. High near 62. Breezy. Chance of precipitation is 90%.

Over 60,000 people without power in SoCal.

Looks like we are going to get more than our fair share from this next storm. Flood watches have been posted that includes my area as well.

[size=83]...FLOOD WATCH IN EFFECT FROM SUNDAY AFTERNOON THROUGH LATE MONDAY NIGHT... The National Weather Service in San Francisco has issued a
  • Flood Watch for a portion of western California…including
    the following areas…Coastal North Bay Including Point Reyes
    National Seashore…East Bay Hills and the Diablo Range…East
    Bay Interior Valleys…Mountains Of San Benito County And
    Interior Monterey County Including Pinnacles National Park…
    North Bay Interior Valleys…North Bay Mountains…Northern
    Monterey Bay…Northern Salinas Valley/Hollister Valley and
    Carmel Valley…San Francisco…San Francisco Bay Shoreline…
    San Francisco Peninsula Coast…Santa Clara Valley Including
    San Jose…Santa Cruz Mountains…Santa Lucia Mountains and
    Los Padres National Forest…Southern Monterey Bay and Big Sur
    Coast and Southern Salinas Valley/Arroyo Seco and Lake San
    Antonio.

  • Impacts include enhanced runoff/flooding in low lying areas and
    waterway, rising water levels/flooding in areal streams, creeks
    and rivers, increased risk of mudslides in steep terrain, downed
    trees and power lines, and damaged or washed out roadways.[/size]

[size=83]An atmospheric river storm pattern will return to Bay Area beginning Sunday morning and extending through the early week. Rainfall from this system will be most intense Sunday night into Monday, with rain accumulation as high as 4-6 inches in the Santa Cruz Mountains and other portions of the Coast Range generally north of the Monterey Bay. Widespread flooding and additional mudslides are likely, given recent rains and enhanced seasonal soil moisture and creek levels. High winds are likely, but will not reach velocities as high as Friday night's system.[/size]

Just saw that Maxwell (N of Sacramento on 5) is flooded, it hasn’t rained much up this way today.

http://www.krcrtv.com/news/local/northstate/maxwell-heavily-flooded-evacuation-centers-opened-in-williams/342132619

Wow, I hadn’t heard about that one. The flooding is covering such a large area. And that’s going to continue to be a problem as long as it keeps raining. The soil is so saturated that any more rain we get, is only going to cause more flooding and mud/land slides.