Flood Tunnel Rejected Again? **UPDATE** It's being considered

[4X4]

Originally Posted by #-3

The way they do business we will go through 2 more floods and it will cost twice as much as they tunnel. And every time we are ready to walk away, they will pretend to be ready to approve it.

I really don't want to jack the thread, but I have to say that maybe if there was an equal opportunity business venture, they might be interested. The ring road is completely different.

Doesn't matter, though. This idea apparently does not work.

[#-3]

Originally Posted by 4X4

I really don't want to jack the thread, but I have to say that maybe if there was an equal opportunity business venture, they might be interested. The ring road is completely different.

Doesn't matter, though. This idea apparently does not work.

Yes, i'm sure there were reasonable arguments on their side for how it went down, and it did eventually get done. But for a long time if felt like they were stringing us along. And they did receive allot of land and money in exchange for the ring road. So there was something in it for them.

I'll stop hijacking the thread now.

[4X4]

Originally Posted by #-3

Yes, i'm sure there were reasonable arguments on their side for how it went down, and it did eventually get done. But for a long time if felt like they were stringing us along. And they did receive allot of land and money in exchange for the ring road. So there was something in it for them.

I'll stop hijacking the thread now.

Agreed. I was hoping for future business, where both parties trusted each other, and things were fair and equitable for everyone.

[Bill Bumface]

Originally Posted by 4X4

Just a half assed idea here, but maybe instead of a really expensive flood tunnel, we could do a little more business with the Tsuu Tina, and build a dry reservoir on their land, that we lease, which only gets used when the Elbow gets threateningly high.

Move around some earth to build a basin in an existing valley near the Elbow, and then build a diversion canal from the Elbow. Sounds wayyy cheaper than tearing up Heritage Drive and building a 5+ km tunnel. Plus the Tsuu Tina get some residual income out of it, and maybe we become (slowly but surely) business partners in many ways.

The Elbow peaked almost 1000 cubic metres per second over normal flow. Lets go with that number because it's easy.

There are 604,800 seconds per week. That means 604 million m3 of excess water per week (this is probably too much as I'm sure the river could keep carrying a good chunk of it).

So if you build a reservoir with an average overall depth of 6m (20' deep, so much deeper in the middle to account for all the shallow areas) you need a reservoir that is 100km2 to hold one week of water, if you leave it bone dry otherwise.

[Rhettzky]

Originally Posted by hulkrogan

The Elbow peaked almost 1000 cubic metres per second over normal flow. Lets go with that number because it's easy.

There are 604,800 seconds per week. That means 604 million m3 of excess water per week (this is probably too much as I'm sure the river could keep carrying a good chunk of it).

So if you build a reservoir with an average overall depth of 6m (20' deep, so much deeper in the middle to account for all the shallow areas) you need a reservoir that is 100km2 to hold one week of water, if you leave it bone dry otherwise.

Exactly. Peak on the Elbow going into the reservoir was 1,240 cubic metres per second. Which was the equivalent of a 1 in 500 year flood event. We were able to significantly drain the reservoir and intentionally flood downtown before the peak flow hit. When the peak hit it filled the reservoir in a couple of hours. The lead flood engineer described it as trying to catch the water from a fire hose with a tea cup.

[GGG]

Originally Posted by Rhettzky

Exactly. Peak on the Elbow going into the reservoir was 1,240 cubic metres per second. Which was the equivalent of a 1 in 500 year flood event. We were able to significantly drain the reservoir and intentionally flood downtown before the peak flow hit. When the peak hit it filled the reservoir in a couple of hours. The lead flood engineer described it as trying to catch the water from a fire hose with a tea cup.

The tunnel to handle a 1000 m^3/s flow is 10m by 10m which is a pretty big tunnel. About 1/3rd of the width of the airport tunnel but slightly taller, and significantly longer.

These water flows that the flood had are tough to comprehend.

[4X4]

Well then build your fancy tunnel! For public art, I vote for ninja turtles to adorn the walls in attack poses.

[Rhettzky]

Originally Posted by 4X4

Well then build your fancy tunnel! For public art, I vote for ninja turtles to adorn the walls in attack poses.

I think it would be awesome if the public art aspect was spent making the outfall look like a giant version of this...

[goodyear]

If this is built, do we get to swim in it before it opens?

[Slava]

So if we build the tunnel is there not an issue of spending a pile of money to save Calgary while doing nothing for communities downstream? Like it's great if this works for us, but the flooding just gets pushed on down the line and those communities have to find their own way to deal with it, right?

The one thing I like about the dry resevoir(s) is that in years of drought we would have some reserve irrigation. The problem is too much water sometimes, but it could almost as easily be not enough water.

[Rhettzky]

Originally Posted by Slava

So if we build the tunnel is there not an issue of spending a pile of money to save Calgary while doing nothing for communities downstream? Like it's great if this works for us, but the flooding just gets pushed on down the line and those communities have to find their own way to deal with it, right?

The one thing I like about the dry resevoir(s) is that in years of drought we would have some reserve irrigation. The problem is too much water sometimes, but it could almost as easily be not enough water.

A dry reservoir really does nothing to stop flooding. To get a good idea of the volume flowing at the peak flow it is the equivalent to the Olympic sized lap pools at Talisman centre (~2500 cubic meters) flowing down the elbow every 2 seconds.



After an hour of peak flow you'd have to be able to hold 1,800 of these pools somewhere. The volume is simply too much to consider a dry pond for.

The best prevention method is conveyance and directing it to a different point in the bow would not increase the flow downstream. It would just divert it to a different point.

[ranchlandsselling]

Are you guys doing the math on the flow of water at peak on the elbow and doing the math on how quickly it would fill a reservior? Shouldn't it be something like half of peak flow? There's an amount that can safely flow through the elbow, so the rate at which the reservior fills shouldn't be the entire flow (if that's how you're doing your math). It's not like the elbow will be dry while the reservior fills.

Need to figure out the capacity that the Elbow can handle (and the bow I guess) and then subtract that from peak flow and use that flow rate for your reservior fill rate.

I think. . .

[Rhettzky]

Just trying to illustrate the volume of water. For reference the flow rate when they were draining the reservoir and people were getting uneasy yesterday was around 40 cubic meters per second. So the capacity the elbow can handle isn't much more before it starts hitting bridge decks.

[Hemi-Cuda]

Looking at what's happening in Medicine Hat and Lethbridge today, last year wasn't a "100 year event", higher water volumes are simply becoming more common at this time of year. Anything that can be done now to prevent future flooding from becoming a disaster should be done

[Ice_Weasel]

Originally Posted by Hemi-Cuda

Looking at what's happening in Medicine Hat and Lethbridge today, last year wasn't a "100 year event", higher water volumes are simply becoming more common at this time of year. Anything that can be done now to prevent future flooding from becoming a disaster should be done

Agreed - just finished skimming the AMEC report on the government of Alberta web page (the report that was referred to in the Herald article a few days ago) and the calculations (which the Herald reporter concluded did not support investment) are based on a 1% probability. Is it really 1%? What if it happens 2 or 3 times in a 100 year period? The NPV of mitigation costs change dramatically with the assumtions.