Flood-related engineering...

[ScienceNostalgia101]

https://www.cp24.com/news/men-rescued-from-flooded-elevator-after-rain-storm-in-toronto-1.4044296

 

Yesterday's Toronto floods got me wondering about better flood control measures and/or better ways things could be designed to be harmed less by a flood.

 

1. It says people needed to be rescued from a flooded elevator. If they're not airtight enough to keep the water out anyway, why not put airholes in them so that people don't have to worry about suffocating from being stuck in the elevator? Why not make them out of glass so that there would be good enough cellphone reception to call for help, and if that doesn't work, to break the glass and escape?

 

2. Why not build a giant half-sphere; concave-up; to collect rainwater such that it could be redirected away from the city and toward farms?

Edited August 8, 2018 by ScienceNostalgia101

[Frank]

1. Buoyant elevators, so they can float above the water level.  Add foam to the bottom, increase counterweight.

2. If the city's sewers can't handle the downfall, it's unlikely there is a cost-effective way to redirect the flow to farms.

3. Stop Climate Change.  Stronger storms are associated with global warming.  Infrastructure built to past spec doesn't handle this new reality well.

 

[ScienceNostalgia101]

For the record, I since realized that in light of Toronto's size, a literal half-sphere is out of the question, but... what about an ellipsoid?

 

1. Ah! That's actually pretty good!

 

2. But sewers are a network of several pipes that each have to be very meticulously placed and fitted. This is just one giant ellipsoid. Cost of materials aside, how delicate an operation can constructing a concave-up ellipsoid be?

 

3. Might be too late for that. Mind you, I'm all for taxing carbon to pay for whatever infrastructure improvements are needed, but I'm not counting on stopping it.

Edited August 9, 2018 by ScienceNostalgia101

[Endy0816]

Well they had air but the water was rising up over the height of the elevator.  Not sure how you would go about balancing having an escape hatch and safety. Glass might actually be a good idea there.

 

Hardly see any ponds in the North. I wonder sometimes if that lack is what causes the crazy levels of flooding to occur.

[Sensei]

Probability of being flooded inside of elevator is smaller than winning on lottery..

Making airholes, just in case of hypothetical flooding, can save somebody from drowning, but can as well kill somebody else, when there is fire in the building (i.e. toxic gases).

Hermetic elevator could kill somebody when there will be some kind of failure disallowing opening door etc. i.e. "stuck in elevator overnight"..

Simply, it's not possible to predict the all possible cases, and make the all possible "just in case" features (and some of them are mutually exclusive).. Only the most probable cases are worth the effort.

 

[Frank]

2. I read this nice article about the feasibility of covering (or maybe a proposal to cover) a city and it involved a structure (like a geodesic dome) and panels of ETFE which need to be pressurized to maintain shape, but can't find said article.  The structure is needed in case a hole develops in the clear panels and to prevent a total collapse as could happen with a pressurized dome.  Crews/maybe robots would repair damage.  I still think it's much too expensive simply as a city cover, but has applications in uninhabitable places on earth and off, like deserts, Mars or the moon.  Wonder how tall a dome is needed to protect from cosmic rays given a 1 atm pressure and reduced gravity? 

 

Found this later: environment - Could permanent self-sustaining biodomes be built on Mars? - Space Exploration Stack Exchange:  https://space.stackexchange.com/questions/10329/could-permanent-self-sustaining-biodomes-be-built-on-mars

 

[ScienceNostalgia101]

On 8/9/2018 at 2:35 AM, Sensei said:

Probability of being flooded inside of elevator is smaller than winning on lottery..

Making airholes, just in case of hypothetical flooding, can save somebody from drowning, but can as well kill somebody else, when there is fire in the building (i.e. toxic gases).

Hermetic elevator could kill somebody when there will be some kind of failure disallowing opening door etc. i.e. "stuck in elevator overnight"..

Simply, it's not possible to predict the all possible cases, and make the all possible "just in case" features (and some of them are mutually exclusive).. Only the most probable cases are worth the effort.

 

"Hermetic" elevator?

 

What of the notion of making it out of glass, such that it can be, like other glass, broken in the case of an emergency? That way they could also see what's going on outside the elevator and whether it's better to stay or go.

 

As for Frank's idea, what I was thinking was concave-up, not concave-down. (Ie. Inverted dome to collect the water.)

Edited August 12, 2018 by ScienceNostalgia101

[Frank]

14 hours ago, ScienceNostalgia101 said:

As for Frank's idea, what I was thinking was concave-up, not concave-down. (Ie. Inverted dome to collect the water.)

I guess I'm trying to say is that putting the largest stress (collected water) in the centre of a large structure, basically at it's weakest point, seems like the hardest way to collect water.  Water is heavy, so diverting it to the ground, or to an aqueduct to avoid pumping, using a dome or other water shedding structure would be a better way, assuming a covered city is desirable in the first place.

 

[CaptainPanic]

Do not use your elevator shaft as a drainage pipe. I do not think that we have to discuss that at length.

However, making sure that not all the water hits the sewers at once is a major change in thinking. Not too long ago, cities were built with the philosophy of removing rainwater as soon as possible. Drainage canals were made as straight as possible to give the water the quickest way out. And that works really well as long as these canals do not exceed their capacity. The new philosophy is to create intermediate storage for the water. If all rainwater hits the sewers during extreme rain, these are almost certain to flood. So, you have to store it first, and release it into the sewers in the hours/days after the rain.

In the Netherlands, a lot of progress is made. Take the "water square" for example:

http://www.urbanisten.nl/wp/?portfolio=waterplein-benthemplein

A square which is used for recreation (relaxing and skating) most of the time, but which can store thousands of m³ of water if needed. Dutch cities are all replacing asphalted and paved areas for grass, which absorbs more water. Cities are building creeks and other drainage systems, which are deliberately not straight, and not only add to the capacity to remove water, but also stores water while it rains. 

[Brett Nortj]

The vest way to 'remedy a flood' is to use salt, or, a derivative of salt, maybe a new chemical, that sucks it up quickly?

I figure this would take about a week, tops to get right. Then, in frequently flooded areas, they could have fire trucks that spew this stuff, or, those big road sweeping trucks dealing with the problem?

Should take a week to get the chemicals right, or, less. I figure maybe some cation based natural stuffs... negative charge to attract the mass, into it?

[druS]

Building rules on lifts (elevators) differ around the world, I speak from experience in Australia and the UK - not USA.

Cell/Mobile reception

Lift cars can and are sometimes made of glass. The core that lifts sit inside are mostly made of structural concrete, though sometimes lightweight infill cores are used. Generally it is a matter for efficiency of structural engineering and you would lose an aweful lot of space to sit the lift outside of the shaft. This is sometimes done in lobbies etc where a steel structure is used with glass, and a glass lift car. You can then see through.

But that does not necessarily give you mobile/cell reception. External glass curtain walls contribute most of the interference issue to mobile/cell reception in city towers. This is overcome by DAS (Digital Antennae System) systems - essentially a repeater system plugged into cable and distributed through the building. Most Premium grade buildings are briefed to maintain reception in lift cars (granted that from personal experience it is not easy to achieve 100%).

But mobile/cell is not an emergency call out system. Lifts are required to have handsets which call back to a central point - generally the lift service provider. AND a stopped lift should be noted back in the control system anyway so that a call out should be alerted.

"Airholes"/Lift Shaft ventilation

This generally depends on the size of shaft and speed of the lift, but most lift shafts will have vents to reduce pressure build up as the cars move up and down. It isn't really for fresh air for human breathing - there should be enough air in a shaft that this is not a problem anyway.

Lift "flood measures"

The lift pit will generally have a sump which in normal circumstances should be dry. You would normally expect  a float system in that sump that is linked to the building control system. This is primarily for equipment protection, but should also set off alarms in this scenario.

I note that far and away the most likely reason behind lift shaft flooding is a burst pipe or some similar internal issue. And this too should have already alerted on the building control systems.

External flooding would be something you would expect the building management to step in on. Though if this is "flash" flooding possibly not quick enough. But someone should know what is going on and be calling in assistance. In flood prone areas, design would usually involve unseen barriers at street level to keep extrernal water out on the basements - up to a limit anyway. If there is catastrophic flash flooding you wont keep the water out. As others have said, it isn't common.

 

 

In general existing building design and should be enough, if implemented reasonably.

Edited August 15, 2018 by druS

[Strange]

2 hours ago, Brett Nortj said:

The vest way to 'remedy a flood' is to use salt, or, a derivative of salt, maybe a new chemical, that sucks it up quickly?

Get a glass of water and so me salt. Pour them on the floor. Watch in amazement as the salt completely fails to suck up the water. 

2 hours ago, Brett Nortj said:

Then, in frequently flooded areas, they could have fire trucks that spew this stuff, or,

Are you concerned at all about polluting the land so nothing will grow?

2 hours ago, Brett Nortj said:

negative charge to attract the mass, into it?

Nonsense. 

[ScienceNostalgia101]

On 8/15/2018 at 2:00 AM, druS said:

Building rules on lifts (elevators) differ around the world, I speak from experience in Australia and the UK - not USA.

Cell/Mobile reception

Lift cars can and are sometimes made of glass. The core that lifts sit inside are mostly made of structural concrete, though sometimes lightweight infill cores are used. Generally it is a matter for efficiency of structural engineering and you would lose an aweful lot of space to sit the lift outside of the shaft. This is sometimes done in lobbies etc where a steel structure is used with glass, and a glass lift car. You can then see through.

But that does not necessarily give you mobile/cell reception. External glass curtain walls contribute most of the interference issue to mobile/cell reception in city towers. This is overcome by DAS (Digital Antennae System) systems - essentially a repeater system plugged into cable and distributed through the building. Most Premium grade buildings are briefed to maintain reception in lift cars (granted that from personal experience it is not easy to achieve 100%).

But mobile/cell is not an emergency call out system. Lifts are required to have handsets which call back to a central point - generally the lift service provider. AND a stopped lift should be noted back in the control system anyway so that a call out should be alerted.

"Airholes"/Lift Shaft ventilation

This generally depends on the size of shaft and speed of the lift, but most lift shafts will have vents to reduce pressure build up as the cars move up and down. It isn't really for fresh air for human breathing - there should be enough air in a shaft that this is not a problem anyway.

Lift "flood measures"

The lift pit will generally have a sump which in normal circumstances should be dry. You would normally expect  a float system in that sump that is linked to the building control system. This is primarily for equipment protection, but should also set off alarms in this scenario.

I note that far and away the most likely reason behind lift shaft flooding is a burst pipe or some similar internal issue. And this too should have already alerted on the building control systems.

External flooding would be something you would expect the building management to step in on. Though if this is "flash" flooding possibly not quick enough. But someone should know what is going on and be calling in assistance. In flood prone areas, design would usually involve unseen barriers at street level to keep extrernal water out on the basements - up to a limit anyway. If there is catastrophic flash flooding you wont keep the water out. As others have said, it isn't common.

 

 

In general existing building design and should be enough, if implemented reasonably.

Thank you for the information! This is the best explanation yet!

[Frank]

Except none of the "sufficient measures"  worked in flooded basement and power out situation given in the OP, so there's room for improvement given our new reality of frequent 1 in 100 year weather events.

 

[druS]

1 hour ago, Frank said:

Except none of the "sufficient measures"  worked in flooded basement and power out situation given in the OP, so there's room for improvement given our new reality of frequent 1 in 100 year weather events.

 

 

Or the building is old and built to old standards. Or they had not worked to best practice modern design. Or the US is behind in building standards. Or they the systems worked which is why emergency teams were there etc etc . Who knows.

Having an emergency does not in itself mean a failure of design.

The 1:100 benchmarks should be under review pretty much everywhere - a basic tool of adaptation. Though in my experience it tends to happen through Green Building Ratings Systems - such as LEEDS in the US. Legislation and the Standard writers tend to lag the latest thinkers such as adaptation measures in LEEDS (or GreenStar in Australia, or BREAM in the UK).

Generally (as I mentioned) this particular issue would be handled  through entries to the basements rising to a 1:100 (or other design) level before ramping down. But it won't stop every eventuality.

On the whole there have been few experiences like the one under discussion. Not something that is going to suddenly impact building standards around the globe. Where say, something like Grenfell Tower fire in London - certainly impacting local building standards here in Sydney, and I suspect a rolling impact around the world.

[Frank]

1 hour ago, druS said:

 

Or the building is old and built to old standards. Or they had not worked to best practice modern design. Or the US is behind in building standards. Or they the systems worked which is why emergency teams were there etc etc . Who knows.

Having an emergency does not in itself mean a failure of design.

The 1:100 benchmarks should be under review pretty much everywhere - a basic tool of adaptation. Though in my experience it tends to happen through Green Building Ratings Systems - such as LEEDS in the US. Legislation and the Standard writers tend to lag the latest thinkers such as adaptation measures in LEEDS (or GreenStar in Australia, or BREAM in the UK).

Generally (as I mentioned) this particular issue would be handled  through entries to the basements rising to a 1:100 (or other design) level before ramping down. But it won't stop every eventuality.

On the whole there have been few experiences like the one under discussion. Not something that is going to suddenly impact building standards around the globe. Where say, something like Grenfell Tower fire in London - certainly impacting local building standards here in Sydney, and I suspect a rolling impact around the world.

Fair enough.  Considered deleting that last post after re-reading yours to the end.  Had a bit of a reaction to everything is fine in the first part.  I understand retrofitting/upgrading is beyond what will happen in real life, sadly.  Not every building has weather proof backup generators, batteries or personnel dedicated to smooth operation, so more passive/all-encompassing  measures seemed interesting to explore.

 

[Endy0816]

Weirdly was what happened in Toronto not a one-off event.

https://www.nytimes.com/2011/08/15/nyregion/two-saved-from-drowning-in-stuck-elevator-on-si.html

Solution: Don't have a basement.

Joking aside people are going to need to rethink construction. Crazy how much damage even low cat hurricanes do when they end up hitting the Northeast.

[ScienceNostalgia101]

On 8/16/2018 at 11:26 PM, Endy0816 said:

Weirdly was what happened in Toronto not a one-off event.

https://www.nytimes.com/2011/08/15/nyregion/two-saved-from-drowning-in-stuck-elevator-on-si.html

Solution: Don't have a basement.

Joking aside people are going to need to rethink construction. Crazy how much damage even low cat hurricanes do when they end up hitting the Northeast.

Huh. Both happened in major cities too.

 

Rather than "don't have a basement," though, why not just have the elevators not go to the basement and for it to be a maintenance area accessible to maintenance personnel only?