Author Topic: Harris County poised to receive grant to study flood tunnel idea  (Read 3558 times)

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Online Elderberry

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Harris County poised to receive grant to study flood tunnel idea
« on: February 20, 2019, 03:34:00 pm »
Houston Chronicle by Zach Despart Feb. 19, 2019

The Harris County Flood Control District is set to receive a $320,000 federal grant to study the feasibility of constructing deep underground tunnels to move stormwater to the Houston Ship Channel without overburdening the area’s bayous.

The grant, from the U.S. Economic Development Administration, will fund a four-month investigation to determine whether such tunnels would be a practical and cost-effective addition to the county’s long-term flood protection strategy. The flood control district has begun work on scores of projects funded by the $2.5 billion flood bond approved last summer, though none to date include underground tunnels.

“The study is basically to look at our ground conditions, including our groundwater table, and compare that to existing technology in the tunnel industry to see if there’s a match,” said Russ Poppe, executive director of the flood control district. “If that’s true, then we can start looking at costs, routes and opportunities we can potentially pursue.”

Engineers envision a system in which tunnels at least 20 feet wide and 150 feet deep use gravity to move water from upstream bayous to the ship channel, in some cases a distance of 30 miles. The region’s flatness, in some areas less than one foot of elevation change per mile, presents a significant obstacle.

More: https://www.houstonchronicle.com/news/houston-texas/houston/article/Harris-County-poised-to-receive-grant-to-study-13628727.php

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So tunnels would be better than wider and deeper bayous and ditches? A tunnel 150 feet deep would be below the water level of the Ship Channel. Are they going to pump this water?

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #1 on: February 20, 2019, 03:54:07 pm »
So tunnels would be better than wider and deeper bayous and ditches? A tunnel 150 feet deep would be below the water level of the Ship Channel. Are they going to pump this water?

As long as the tunnel outlet is lower than the inlet, gravity will move the water regardless of depth in between.  Works the same as a gravity syphon with a hose.

The problem is areas where it is already built up without room for ditches this big.
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Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #2 on: February 20, 2019, 04:53:23 pm »
As long as the tunnel outlet is lower than the inlet, gravity will move the water regardless of depth in between.  Works the same as a gravity syphon with a hose.

The problem is areas where it is already built up without room for ditches this big.

If those tunnel bottoms didn't have a continuous slope gradient, then after a flood, there would remain a stagnant mosquito haven pool at every dip of the tunnel. At least bayous have wildlife that devour mosquitos.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #3 on: February 20, 2019, 04:57:58 pm »
If those tunnel bottoms didn't have a continuous slope gradient, then after a flood, there would remain a stagnant mosquito haven pool at every dip of the tunnel. At least bayous have wildlife that devour mosquitos.

I would expect it to be full of water except at the inlet and outlet.
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Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #4 on: February 20, 2019, 05:08:59 pm »
I would expect it to be full of water except at the inlet and outlet.
So for each flood event, the flood water would have to push all the water in the fully filled tunnel out to the ship channel before any new flood water was able to be discharged? If it was a fast rising flood, the water, taking paths of least resistance would not even enter the tunnel.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #5 on: February 20, 2019, 05:32:27 pm »
So for each flood event, the flood water would have to push all the water in the fully filled tunnel out to the ship channel before any new flood water was able to be discharged? If it was a fast rising flood, the water, taking paths of least resistance would not even enter the tunnel.

Gravity still works, even in a flood.  If water comes to mouth, it is going to flow. 
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Offline catfish1957

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #6 on: February 20, 2019, 05:40:33 pm »
Gravity still works, even in a flood.  If water comes to mouth, it is going to flow.

Had involvement in this as a EHCMA participant back in the early '90's.  Easy solution would be to dredge the HSC, but no one wanted to open that can of worms.
I display the Confederate Battle Flag in honor of my great great great grandfathers who spilled blood at Wilson's Creek and Shiloh.  5 others served in the WBTS with honor too.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #7 on: February 20, 2019, 05:44:37 pm »
Had involvement in this as a EHCMA participant back in the early '90's.  Easy solution would be to dredge the HSC, but no one wanted to open that can of worms.

This is to get the water to the HSC, the backup before the channel.
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Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #8 on: February 20, 2019, 06:01:44 pm »
Gravity still works, even in a flood.  If water comes to mouth, it is going to flow.

Eventually. And maybe not where you want it to. 

For your fully filled tunnel, except for each end. Say one end just below Addicks Reservoir, with the other end into Buffalo bayou. For a distance of say 30 miles.

How much force would you imagine that flood water entering the unfilled end of that fully filled 30 mile tunnel would be needed to overcome both the inertia of all that water as well as the stationary friction of the water interface with the tunnel surface? And much time would be needed before the pipe was fully filled with new flood water?

I think you made a big mistake stating that only the ends of the tunnel would not be filled. That tunnel would have to be empty before any flood to be any help at all.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #9 on: February 20, 2019, 06:05:12 pm »
Eventually. And maybe not where you want it to. 

For your fully filled tunnel, except for each end. Say one end just below Addicks Reservoir, with the other end into Buffalo bayou. For a distance of say 30 miles.

How much force would you imagine that flood water entering the unfilled end of that fully filled 30 mile tunnel would be needed to overcome both the inertia of all that water as well as the stationary friction of the water interface with the tunnel surface? And much time would be needed before the pipe was fully filled with new flood water?

I think you made a big mistake stating that only the ends of the tunnel would not be filled. That tunnel would have to be empty before any flood to be any help at all.

How fast does pressure differential travel in an incompressible fluid?

I may be wrong.  But I have found no discussion of pumps with this one or the ones already existing in DC.
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Online rustynail

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #10 on: February 20, 2019, 06:19:49 pm »
A wild kayak ride?

Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #11 on: February 20, 2019, 06:51:57 pm »
How fast does pressure differential travel in an incompressible fluid?

I may be wrong.  But I have found no discussion of pumps with this one or the ones already existing in DC.

You are looking at the wrong area. The tunnel is a "Pipe". You should be looking at the dynamics of non-steady viscous flows in pipe.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #12 on: February 20, 2019, 07:04:47 pm »
You are looking at the wrong area. The tunnel is a "Pipe". You should be looking at the dynamics of non-steady viscous flows in pipe.

I give up.  You win.  This won't work and the ones they have already built in other areas don't work either.
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Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #13 on: February 20, 2019, 07:18:44 pm »
I give up.  You win.  This won't work and the ones they have already built in other areas don't work either.

As kids we used to explore for miles under the city in the storm sewers. Not during a flood, mind you, and none of them were filled with water. Well, other than a trickle flow.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #14 on: February 20, 2019, 07:21:38 pm »
As kids we used to explore for miles under the city in the storm sewers. Not during a flood, mind you, and none of them were filled with water. Well, other than a trickle flow.

You should let San Antonio know the tunnels they have used for a couple decades won't work.

https://www.expressnews.com/150years/major-stories/article/History-River-Tunnel-0711-6378378.php
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Offline GrouchoTex

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #15 on: February 20, 2019, 07:23:12 pm »
I thought this idea was proposed 20-30 years ago and scrapped back then?

3rd reservoir has also been proposed.

Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #16 on: February 20, 2019, 07:38:58 pm »
You should let San Antonio know the tunnels they have used for a couple decades won't work.

https://www.expressnews.com/150years/major-stories/article/History-River-Tunnel-0711-6378378.php

Aren't you the one that just said they don't work?

You tell them.

Offline catfish1957

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #17 on: February 20, 2019, 09:35:38 pm »
This is to get the water to the HSC, the backup before the channel.
Having a cleaner and deeper HSC would have taken a first flush load off all the ancillary tribuataries.... Greens, Buffalo, Sims, etc.

Hydrology studies confirmed, but again......   No one wanted the issues associated with dredging the HSC.
I display the Confederate Battle Flag in honor of my great great great grandfathers who spilled blood at Wilson's Creek and Shiloh.  5 others served in the WBTS with honor too.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #18 on: February 21, 2019, 02:40:35 pm »
Having a cleaner and deeper HSC would have taken a first flush load off all the ancillary tribuataries.... Greens, Buffalo, Sims, etc.

Hydrology studies confirmed, but again......   No one wanted the issues associated with dredging the HSC.

Houston Ship Channel gets dredged from time to time already.  It will silt up and have to maintain the depth.

Harvey-Related Dredging Of Houston Ship Channel Almost Done
https://www.houstonpublicmedia.org/articles/news/city-of-houston/2018/03/29/276020/harvey-related-dredging-of-houston-ship-channel-almost-done/

However, this project is about getting the water to the Houston Ship Channel.
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Online Elderberry

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #19 on: February 21, 2019, 02:46:15 pm »
Is a massive tunnel system the answer to Houston’s flood woes?

Other Texas cities have built underground channels to divert stormwater. Experts say it might not be the right way to go for Houston, but that it's still worth exploring.

Texas Tribune by Natalia Alamdari July 6, 2018

https://www.texastribune.org/2018/07/06/hurricane-harvey-floods-houston-water-tunnel/

Quote
So would such a tunnel system really be a logical solution for Houston’s flood woes?

Drilled 100 to 200 feet underground, the underground channels act as temporary storage for floodwater during intense rainstorms, said Larry Larson, a senior policy adviser at the Association of State Floodplain Managers. Once the rain has stopped, the stormwater can be used for a variety of purposes. It can be pumped back to the surface into a river or wetlands or even used to recharge aquifers.

If cities have a section of river that regularly overflows, a tunnel can convey extra water underground and help reduce the amount of water that flows onto land during storms, said Christof Spieler, project manager of the Greater Houston Flood Mitigation Consortium. Large-scale tunnels can also act as an additional set of waterways, taking pressure off undersized drainage networks, he said.

But Larson and Spieler said it's hard to tell if such a system would make sense for Houston — a low-lying coastal city that's experienced three 500-year floods in the past three years.

The area's soft soil and high groundwater table would likely complicate construction, Larson said. And while most cities have flood zones concentrated around rivers and other bodies of water, Spieler said Houston experiences more dispersed flooding

"It's not one big waterway, but dozens of them, and no clear floodplains," he said.

Because flood patterns vary across watersheds, Spieler said what might be a good solution in one part of the county wouldn't necessarily be the best choice in another.

“[Houston has] the worst of conditions — huge development and you’re in terrain that’s flat as a pancake. You can’t get the water out,” Larson said. “You’re even subject to coastal storm surge. Houston’s really in a bullseye there.”

More at link above.

Offline catfish1957

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #20 on: February 21, 2019, 02:59:45 pm »
Houston Ship Channel gets dredged from time to time already.  It will silt up and have to maintain the depth.

Harvey-Related Dredging Of Houston Ship Channel Almost Done
https://www.houstonpublicmedia.org/articles/news/city-of-houston/2018/03/29/276020/harvey-related-dredging-of-houston-ship-channel-almost-done/

However, this project is about getting the water to the Houston Ship Channel.

LOL....   Cursory "minor surgery" dredging to make sure waterways are operable for barges and ships. 

I am talking DREDGING to clean the sucker up.  Big difference, and  a game changer that would help eleviate problems upstream.
« Last Edit: February 21, 2019, 03:01:17 pm by catfish1957 »
I display the Confederate Battle Flag in honor of my great great great grandfathers who spilled blood at Wilson's Creek and Shiloh.  5 others served in the WBTS with honor too.

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #21 on: February 21, 2019, 03:02:28 pm »
LOL....   Cursory "minor surgery" dredging to make sure waterways are operable for barges and ships. 

I am talking DREDGING to clean the sucker up.  Big difference, and  a game changer that would help eleviate problems upstream.

It is already dredged to 40 feet.  How deep do you think they should go?
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Offline Idiot

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #22 on: February 21, 2019, 03:20:18 pm »
It is already dredged to 40 feet.  How deep do you think they should go?
LOL....you have the patience of Job.  :laugh:

Offline thackney

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #23 on: February 21, 2019, 03:47:08 pm »
LOL....you have the patience of Job.  :laugh:

Besides the Washburn Tunnel with the top at 45 feet deep, there are a few other issues going much deeper.

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Offline catfish1957

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Re: Harris County poised to receive grant to study flood tunnel idea
« Reply #24 on: February 21, 2019, 05:44:46 pm »
It is already dredged to 40 feet.  How deep do you think they should go?

I think that depth was mid-channel wasn't it?  (for waterway navigation) I am talking about the volume near or prior to industrial development.

During the ECHMA meetings, the word "epic" was often used to describe what "best case" drainage benefits say from dredging the HSC from inside the loop to the inlet of the bay.  OF course a high priced feasibility/ cost effectiveness study shot it down.  And of course this is several years before Allison or Harvey. 
I display the Confederate Battle Flag in honor of my great great great grandfathers who spilled blood at Wilson's Creek and Shiloh.  5 others served in the WBTS with honor too.