Tuesday, December 04, 2007

Long Island Sound tunnel: One Thumbs Down, Lots of Questions

The New London Day is the first paper I've seen to comeout against the Long Island Sound tunnel. An editorial in the Day on Sunday said:

If you thought the Broadwater plan to build a floating liquefied natural gas terminal in the middle of Long Island Sound was one of the worst, environmentally abominable ideas ever proposed for the 110-mile-long estuary, consider the plan announced recently by a New York multimillionaire.

The editorial notes, by the way, that New London is about 100 miles away from where the tunnel would be built. From even further away, near Dallas (does it reflect badly on a Long Island Sound blog that the two people who comment most frequently, Bryan Brown and Sam Wells, both live in Texas?), Bryan Brown has sent me some worthwhile thoughts on the tunnel, in response to this post. Here's part of what Bryan says:

Where are they going to dump the material from the tunnels? It's 500 million cubic feet or 18.4 million cubic yards of rock and soil. If they used it as fill, 100ft of it would cover 116 acres.

If half the borings come out of the LI tunnel, how are they going to move 9.2 million cubic yards? At 30 cubic yards per load, that's 300,000 truck trips.

Have 55-ft diameter tunnels been bored before? I haven't found any that are that big. The tubes all seem to be less than 40ft in diameter.

24 million gallons of gasoline per year saved seems reasonable based on a trip that's 30 miles shorter. Is it still 24 million gallons in 2025 when we're all driving hybrids or electric cars that get 100mpg?

How much of the so-called green benefit from this project gets eaten by the CO2 emissions associated with building it? Cement is responsible for GHG and this project will take a lot of concrete. The construction equipment will be burning diesel (or maybe CNG or LNG).

If Sam is right and it induces more traffic, that would reduce or even wipe out the so-called green benefits, particularly if there is no rail component.

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3 Comments:

Blogger Sam said...

I think most trucks can only carry 12 yards, although there is a "super-17" size I believe - larger trucks would require weight examptions and could easily tear up the existing roads. Watch out in case somebody wants to landfill a huge wetlands or something, since we're talking a lot of rock here.

Then there's the boring machine itself, don't forget that. It will probably be an electrified monster approximately the same diameter of the tunnel tube - and that electricity needs to come from somewhere. Since there is so much waste rock and the boring machine weighs so much, a railriad system is often used.

The waste then has to be dewatered in a large borrow pile area; sometimes it is treated with lime if it is acidic or is considered toxic.

So much to think about ... but even before the real work starts ... one has to blow up the Sound! You heard right, seismic testing is required to ascertain the how fissured and stratified the sediment is, either my using air guns or dynamite (or both).

After blowing up that part of the Sound one needs to electrify it! Oh yes, one much ensure the proper depth and path of the tunnel boring, so several kinds of wires and transponders are used to guide the boring machine. Most of this cabling is taken away when done but I think one is left so as to monitor the floor of the Sound for seismic movement.

Us Texas dudes must be weird to think up all this stuff, huh?

10:27 AM  
Anonymous Bryan said...

Sam,
Greetings from Wylie!
I recall reading in your blog about the seismic testing they did in your local waterbody, exploring for oil. It sounded pretty awful when I read it. Do you think the seismic testing up for the proposed tunnel would be similar?

11:33 AM  
Blogger Sam said...

Hey Bryan, I think some seismic would have to be done is there was a concern about the geology - perhaps Tom knows whether it is consolidated rock or what. But after snooping around, the main source of seismic recording is the tunnel boring machine (TBM) itself, which makes loads of P- and S-curve vibration waves. Check out Yucca Mountains and some of the newer, large tunnels today. Lots of seismic is used. -Your buddy down by the Rio Grand.

3:40 PM  

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