Second Narrows water main tunnel project

[jollyburger]

Maybe they can dig some Skytrain tunnels while they are down there.

Metro Vancouver has begun pre-construction on a $430-million, five-metre wide tunnel under the Second Narrows to supply drinking water to much of the Lower Mainland.

http://www.nsnews.com/news/work-begi...nel-1.23163519

[Alex Mackinnon]

It would be much easier to build a bridge for the Skytrain. This tunnel is going to be quite deep. They have to get below any potential slip surfaces for landslides that are triggered by earthquakes. This should be a 1-in-10,000 year earthquake event design, so it's got quite the high design standard.

I don't think Translink designs it's infrastructure to quite as high a standard, since water mains basically can't be brought offline for lengthy repairs after an earthquake without potentially causing huge societal problems. The skytrain being down, while a giant pain would be less likely to stop large swaths of the city from being inhabitable.

This should be a very similar project to the Port Mann Main Water Supply Tunnel, which a couple of my colleagues managed. The shafts are probably designed to sheer a little bit in the event of a large earthquake, without damaging the pipes in the shafts. It's pretty cool stuff.

[jollyburger]

Originally Posted by Alex Mackinnon

It would be much easier to build a bridge for the Skytrain. This tunnel is going to be quite deep. They have to get below any potential slip surfaces for landslides that are triggered by earthquakes. This should be a 1-in-10,000 year earthquake event design, so it's got quite the high design standard.

I don't think Translink designs it's infrastructure to quite as high a standard, since water mains basically can't be brought offline for lengthy repairs after an earthquake without potentially causing huge societal problems. The skytrain being down, while a giant pain would be less likely to stop large swaths of the city from being inhabitable.

This should be a very similar project to the Port Mann Main Water Supply Tunnel, which a couple of my colleagues managed. The shafts are probably designed to sheer a little bit in the event of a large earthquake, without damaging the pipes in the shafts. It's pretty cool stuff.

Sorry, I was just joking

They said it's pretty much identical to the Port Mann project and they are also replacing pipe in Stanley Park (2020-2024). I guess we know why it's called Pipeline Road too.



http://www.metrovancouver.org/servic...k-water-tunnel

[Alex Mackinnon]

I can talk about that one more in a couple weeks. With some luck I may be designing part of that project.

[aberdeen5698]

Originally Posted by jollyburger

Maybe they can dig some Skytrain tunnels while they are down there.

I wonder why they didn't size all three interior pipes the same size? It seems like a bit of a waste of space. Leaving space for inspection robots, perhaps?

[Alex Mackinnon]

Originally Posted by aberdeen5698

I wonder why they didn't size all three interior pipes the same size? It seems like a bit of a waste of space. Leaving space for inspection robots, perhaps?

Different operating pressures for different local reservoir destinations and feed sources. It lets Metro Vancouver pump less, which saves lots of money.

If only 1 or 2 of the feed lines need to be pressurised above the Capilano or Seymour Reservoir level, then the only have to pump some of the water instead of all of the water.

If I recall correctly, 2 of the lines come from Seymour and 1 line comes from the Capilano Reservoir which is at a lower elevation.

[flipper316]

Originally Posted by jollyburger

Sorry, I was just joking

They said it's pretty much identical to the Port Mann project and they are also replacing pipe in Stanley Park (2020-2024). I guess we know why it's called Pipeline Road too.



http://www.metrovancouver.org/servic...k-water-tunnel

Holy smokes I can't wait for the anger that'll come from the environmentalists over this. It'll make Hawthorne Park look like a picnic.

[Alex Mackinnon]

Originally Posted by flipper316

Holy smokes I can't wait for the anger that'll come from the environmentalists over this. It'll make Hawthorne Park look like a picnic.

What for? It's a tunnel specifically to avoid significantly digging up the park.

[flipper316]

Originally Posted by Alex Mackinnon

What for? It's a tunnel specifically to avoid significantly digging up the park.

Pretty sure there's gonna be some trees that are going to be cut down. Look what happened in Burnaby.http://www.burnabynow.com/news/forti...cre-1.23086242