Oroville Dam – If this goes south it could change the course of dam management immediately.

[Smike]

There are hundreds of earthen dams with the exact same (untested) emergency spillway design as the failing Oroville Dam. I know of one in particular in PA which had water to within several feet of going over the emergency spillway due to a hurricane many years ago. And currently that dam is allowed to raise (i.e. give up flood storage buffer) each year to support recreational releases. If Oroville fails, no doubt that Congress will be reviewing all dams of the same type and possibly suspending any use of storage or flow plans for recreational purposes until future assessments are made. This could be disastrous for any river which depends on tail water flow plans to maintain the fishery.

I think the WB of the Delaware is safe since the spillway has been used in operations for years (proven safe) For Frances Walter on the Lehigh, this is same design as Oroville and untested just like Oroville. I’m curious to look at others across the county to see which fall into this.

 

[vcregular]

I am pretty sure Blue Marsh topped the emergency spillway and flowed thru the woods after the flood of 2006 as well as after 2011. This is not what the Corps ever wants to see.

Vid is here of the 2011 event - https://www.youtube.com/watch?v=Upxm_e9IYTc

FEW came with in 9' of the emergency spillway in 2006, but that still is 15% of storage. Over 22,000cfs was flowing into FEW during the peak of the event, and the gates were shut to allow no water to release until downstream flooding subsided. Then the gates were opened to 10,000 once downstream waters began to subside. Some frame of reference.

 

[Smike]

You point aligns with the crisis in Oroville CA, which is ‘Designed In safety” (not tested or proven) vs. “Tested in safety” Lehigh is Designed in at this stage, and based on the fact the design is exactly the same as the Oroville dam (which is failing) it may get deemed suspect and all recreational operations ended until further evaluation. They held back the water in 2011 riding purely on the design in factor would prove true if the water spilled over the emergency spillway. Same as what happened in Ca except it did spill over and the design was proven to be extremely below design threshold.


For the dams with proven safety via 'Tested in' designs (such as Blue Marsh) not much to change or be suspect of.

 

[wbranch]

Smike wrote;

I think the WB of the Delaware is safe since the spillway has been used in operations for years (proven safe)

If you consider 44,000 cfs flowing down river on June 26, 2006 "safe" well we might need another definition of the word. Thirty-six (36) inches of water ran through my cabin. Cabins at West Branch Angler got lifted off of their foundations and floated down the river. Many drift boats wound up dozens of miles down river.

The NYC water authority was aware of the increasing level of Cannonsville. Albeit the flood had nothing to do with the integrity of the earthen dam. However just two years ago the earthen dam did spring a leak when test holes were bored to begin construction on the hydro electric plant was is proposed.

 

[FarmerDave]

I agree that these types of emergency spillways need to be re-examined, and probably reinforced. Uncontrolled discharge over the top of an earthen dam never ends well.

However, the Oroville dam had issues for several years that were ignored. The only reason the emergency spillway was used in the first place was because the main concrete spillway was severely damaged and using it greatly increased the amount of damage.

Well, the emergency spillway couldn't take it. Water was even going over the parking lot, which apparently was not part of the emergency spillway. So now they are using the heavily damaged main concrete spillway to draw down the lake to repair the emergency spillway and prepare for the next storm.

So yea, this should change the course of dam management. But the first thing they need to start doing is their job. Keep them better maintained.

They were likely complacent after several years of drought.

 

[vcregular]

Who knows what sort of precedent this will set. But as I am sure you know it all comes down to risk. How much is the Corps for instance willing to take with Francis E Walter for example? Just by how they manage the yearly flow plans they are very conservative with how much storage encroaches into flood storage. Since it was commissioned in 1961 it has never topped, and has only come within 15% of the top. Designing a bombproof spill way is not the answer. But rather making a bigger hole to collect the water is the only answer for more effective flood control capabilities. But that is where the risk factor comes into play

 

[Smike]

I don't think we are all waking up to realize a bunch of dams are now hazards. But if Oroville fails, and it causes hundreds of billions in damages, and displaces 300-400,000 people from their homes, you know heads are going to role indiscriminately and knee jerk reactions are going to go out in rapid fire.

Its not far fetch to hear an executive order that all earthen dam reservoir must abandon all non flood related activities immediately until they review and determine if there is a danger. (sound familiar?) We are living in the age of instant over reaction which results in little safety.

 

[sarce]

Here in VA, most large dams are required to pass the flood from a 90% PMP (probable maximum precipitation - varies by location but typically around 20-28" in 6 hrs) through the emergency spillway if their failure would be a threat to roads and residences downstream. In theory if the emergency spillway is structurally sound, the dam will be just fine for almost all ridiculously heavy rain events. Most eastern states are similar with the regs. This doesn't consider the possibility of multiple large rainfall events in a short amount of time (like a few weeks or months). Out west the snowmelt plays a huge role as well, though I am unfamiliar if CA incorporates that into the regs. Oroville is a repeat large storm situation plus snowmelt - hard to construct a dam large enough to handle that. I work in this field, just thought I'd add this info.

 

[ryanh]

I fished the Yuba years ago chasing steelhead. Even under the best conditions that is an extremely strong flowing river. I fear that this is not going to let up as the record snow pack will continue to melt through May. In other words wait till they get a warm up in the sierras and several inch rainfall event all at the same time and it will be game over.

FEMA publishes maps on 100 year flood plain....A catastrophic failure of that dam will be more like a 500 year or 1000 year event.

 

[salmonoid]

I had a geology professor who matter of factly stated that being a geologist pretty much was bad when it came time to buy a home.

As a geologist, you saw the evidence everywhere you looked:

1) Old landslide scars on hillsides, or evidence of even larger mass wasting (think Gros Ventre slide, or the Heart Mountain klippe/detachment block),
2) Subsidence from mines
3) The 100 and 1000 year flood floodplains
4) Sinkholes in karst regions
5) The occasional meteorite impact site
6) Forest fire risk
7) Old or active faults

Vegetation tends to obscure some of those signs, but they exist if you look hard enough.

We try to contain nature the best way we know how, but #2 in the list above is the only one we have any control over. If you're concerned about your house or cabin getting washed away, don't build the darn thing on a floodplain. If you fear a dam giving way, don't build downstream from it, or if you do, make sure you're on a major height of land (but not one that would landslide following a heavy rain, on a defoliated hillside, or that has a fault going through it).

 

[troutbert]

salmonoid wrote:

If you're concerned about your house or cabin getting washed away, don't build the darn thing on a floodplain.

Good advice.

In Lock Haven, on the river walk, right next to where the bridge crosses the West Branch Susquehanna, there's a stone pillar with a record of floods of Lock Haven.

According to this, floods occurred in:

1744, 1758, 1772, 1784, 1786, 1800, 1829, 1846, 1847, 1851, 1865, 1889, 1894, 1918, 1923, 1936, 1946, 1950, 1964, 1972, 1980

The planning for the dike system began in 1980.

 

[ryanh]

Geologist also have a really unique perspective on time. I had a geologist friend that said her margin of analytical error was plus or minus one million years...

 

[Susquehanna]

Geologist also have a really unique perspective on time. I had a geologist friend that said her margin of analytical error was plus or minus one million years...

I like this. :lol:

As far as the Oroville Dam, it is a real tragedy. However, the national attention our failing infrastructure is going to get in is very valuable.
Hopefully we can fix all our dams.

 

[FarmerDave]

Susquehanna wrote:

Geologist also have a really unique perspective on time. I had a geologist friend that said her margin of analytical error was plus or minus one million years...

I like this. :lol:

As far as the Oroville Dam, it is a real tragedy. However, the national attention our failing infrastructure is going to get in is very valuable.
Hopefully we can fix all our dams.

I'll second that, even the first part.

 

[krayfish2]

I'd suspect that we have many dams in less than favorable condition than we want to admit to. Similar to when they did a bridge inspection and realized, "wow, our 100 year old bridges are falling apart".

Dam failure will be catastrophic for people, property and the landscape. Not ignoring those facts but I'd like to point out that it's a HUGE source of drinking water for the state. That will have huge ramifications if the dam fails.

The volume being released, the force and massive erosion has me thinking only an act of God will prevent the dam from failing. Things don't look good at this point. I also suspect that the lake reaching that level was a serious miscalculation or improper management of the releases. Most if not all PA dams are in place for flood control and operated accordingly. That's why they dump water BEFORE a major event or hold water DURING a major event. Yes, it baffles tailwater Anglers and sometimes makes fishing them inconvenient.....but that's the nature of the beast.

 

[pcray1231]

They're in a pickle but I'm optimistic they avert disaster. It will cost lots of money but I don't see that they have a choice.

1. Drop water levels via damaged main spillway to ensure no flow over emergency spillway. They pretty much did this. Gotta keep it low for some time. Barring really huge rains in the coming months (or years), this is doable. The lower they can get that lake the more leeway they have to handle some rain. It's good that they are gaining on it despite still high flows. Immediate danger is lessening.

2. With no flows, repair erosion on the emergency spillway. Then build a new emergency spillway, with a concrete raceway down to the river. May take years.

3. Shut water off at main spillway, raise lake, let new spillway handle it. Repair main spillway. This will really be the danger period, but won't take as long. Back to 2 working spillways.

4. Build Marysville dam. The dang thing was approved in 1966. They haven't broken ground yet cause it's still tied up in courts. Water rights and politics. Exhibit A of why infrastructure can't be built today! Time to push matters. Oroville was never designed to be able to handle this river on its own, even with 2 working spillways. That's why they're in this mess. It was designed to have more constant flows because it would work in concert with Marysville, and nearly double the retaining capacity of the system, allowing better absorption of the high and low outputs of the river system.

Note, many of those evacuated below who are cursing the dam, would already be flooded without it. Still, the above is essentially a 20 year plan while just hoping you don't get a 100 year flood. 80% chance of averting disaster and requires spending boatloads of money.

 

[gulfgreyhound]

History does repeat itself,ie the Johnstown Flood. Mans folly is in thinking he can dominate Mother Nature. GG

 

[FarmerDave]

pcray1231 wrote:
They're in a pickle but I'm optimistic they avert disaster. It will cost lots of money but I don't see that they have a choice.

1. Drop water levels via damaged main spillway to ensure no flow over emergency spillway. They pretty much did this. Gotta keep it low for some time. Barring really huge rains in the coming months (or years), this is doable. The lower they can get that lake the more leeway they have to handle some rain. It's good that they are gaining on it despite still high flows. Immediate danger is lessening.

2. With no flows, repair erosion on the emergency spillway. Then build a new emergency spillway, with a concrete raceway down to the river. May take years.

3. Shut water off at main spillway, raise lake, let new spillway handle it. Repair main spillway. This will really be the danger period, but won't take as long. Back to 2 working spillways.

4. Build Marysville dam. The dang thing was approved in 1966. They haven't broken ground yet cause it's still tied up in courts. Water rights and politics. Exhibit A of why infrastructure can't be built today! Time to push matters. Oroville was never designed to be able to handle this river on its own, even with 2 working spillways. That's why they're in this mess. It was designed to have more constant flows because it would work in concert with Marysville, and nearly double the retaining capacity of the system, allowing better absorption of the high and low outputs of the river system.

Note, many of those evacuated below who are cursing the dam, would already be flooded without it. Still, the above is essentially a 20 year plan while just hoping you don't get a 100 year flood. 80% chance of averting disaster and requires spending boatloads of money.

Either you are making it more complicated than it needs to be, or don't realize there are 3 discharges/spillways. The main power generating discharge is way off to the right in the concrete part of the dame. I think it is actually bottom release. This spillway is apparently fine. and it I can also handle enough flow in the summer to lower levels to well below the two other spillways.

Emergency spillway is just another word for cup too full, and it runneth over. Did anyone notice how they called that 97% full? Running over the top is 97% full. Hmmm.

Anyway, it shouldn't be ignored, but it is clear to me that the best line of defense would be lower the dam lake to well below both overflow sipllways, and fix the main overflow chute first.

Once that is done, THEN fix the emergency spillway.

This was the first time it was used, and it wouldn't have been used now if not for the huge hole in the main chute.

 

[krayfish2]

Everyone is worried about overflow spillway. I would be more concerned about the main Spillway that is being disintegrated as we speak.

If the lake was at "97%"..... Where did these guys think additional rains and the snow melt from near record snows was going to go? Mismanagement is as much to blame as is the faulty design of the overflow spillway.

 

[CLSports]

The last few posts regarding infrastructure spending are spot on. We need to invest more in our nations's infrastructure. We are also seeing highways and bridges that were built over 50 years ago beginning to fail. They were only designed to last 50 years and this is very evident in PA where we have many bridges that are in the critical stages. PENNDOT has done a lot in the last few years to address this issue, but they need more Federal funding. The PA Turnpike bridge over the Delaware River is another example.