> While Venture Global declined to make officials available for interviews, it has insisted its steel wall is designed to withstand a once-in-500 years storm.
The problem with those "once-in-500 years" figures is that they are based on historical data - and climate change is rapidly invalidating that data. Climate change doesn't mean it's 1.5°C warmer year-round, or the sea level is 20cm higher worldwide: it means weather becomes more more extreme. What was a "once-in-500" event a few decades ago might turn into a "once-in-25" event a few years from now. We are already noticing those changes in day-to-day life!
It’s not really a problem, you just adjust the size of your assumed storm. We have lots of climate models and data to adjust predicted sizes.
Climate change effects are already being included when calculating wind and wave loading in many codes.
The real issue is that engineering codes use frequentist methods which make it hard to consider uncertainty, which often makes it unclear what the real safety factors are. This issue is being solved by using probabilistic engineering techniques, and in future, more sophisticated causal inference.
Climate. Models aren't really specific enough to predict a new 500 year storm in a specific location.
Those thresholds and definitions are based on the data record, and already encoded into regulation and a 100 years of construction.
What we see instead is Regulators simply increasing the requirements from a X year storm to a 2X year storm, and leaving the definitions. This is what I have seen with the California building code
> It’s not really a problem, you just adjust the size of your assumed storm.
Adjusting how you call the storm doesn't make the wall bigger: that's the problem. (It also makes their statement untrue in the present day, regardless of if it was true when the wall was designed.)
The real problem I have with the "X-hundred year Y" things is that it leads even technical and mathematically inclined people to get confused, let alone people who are neither. It makes it sound like it happens on a schedule, or that it is not common / a minuscule risk.
A "100 year flood" implies there's a 1-.99^30 or a 26% chance of happening over the life of a mortgage.
I always feel like if it were phrased in that way people would grasp the concept better. Same idea holds for any X and Y.
These make for great entertaining/ filtering threads though.
Obvious who knows probability and who's a PE, plus various levels of self-awareness. Otherwise intelligent ppl taking terms at face value that are actually terms-of-art / industry lingo. And sometimes grossly misapplying such terms.
And that's before you even get into politics/ ideology, should you want to judge such things.
It's a 6d personality/intelligence grid.
Throwing 100 interviewees into a hypothetical thread like this is the closest I can think of to the perfect early round hiring process.
A "100 year storm" is a storm with a 1% probability of occurrence within any given year.[1] So a 500-year storm has an 0.2% annual occurrence probability.
Those of us who understand probabilities immediately recognise that even assuming the base-line probabilities are correct, this will occur far more frequently than once in 100 years.[2]
And of course, the probabilities require a known historical distribution, which itself changes over time (climate change being only one of multiple factors). It is possible to make inferences based on the observed rate vs. intensity or magnitude of events. In many cases these follow an inverse-log relation, such that order-of-magnitude greater intensity events occur with an order of magnitude less frequency. Tracking the more-frequent, lower-intensity incidents actually gives a good proxy for how often higher-intensity events will occur.[3]
2. A 1% probability event has a 99% probability of not occurring. For a period of time, raise 0.99 to the power of the periods occuring. Over a 100 year period, that's 0.99^100, or a 63.4% chance of no such events occurring. For the probability of k occurrences over n periods you'd apply the binomial distribution: <https://en.wikipedia.org/wiki/Binomial_distribution>.
3. This is a relationship which applies to a whole host of events, and is very frequently observed in general physical phenomena. Asteroid impacts, earthquake intensities, volcanic eruptions, storms, wildfires, terrorist attacks, and the like.
It's plenty, because 30yrs is usually the rule of thumb for enough, and extreme events are more likely to be recorded even in the absence of/before there were regular record intervals.
There are well established probability distributions for these things, so you're really just solving for which published curve and maybe a magnitude multiplier and seeing where your data fits.
Also there's uncertainty baked-in and accounted for at every step of the engineering design process.
Eg. Geotechnical engineers love to calculate 6 digits to 4 decimals then throw in a 400% factor of safety.
You are misunderstanding the engineering language in a term-of-art way.
1 in 500 year storm is a one-year probability of 1/500, based on now.
There is no implied or expected future change that needs to be considered. That's already baked into selecting the design-storm-interval of 1 in 500 vs 1/250 or whatever else.
A 1 in 1000 year event need not be, and likely won't be, the same/valid probability in the year 3024. Or even 2074. And that's OK. The engineers know that.
As a marketing slogan, withstanding "once-in-500 years" storms is intended to (a) disconnect the listener's brain from the reality of climate change, and (b) ensure that in a decade or so there will be repeat business when it has to be replaced/upgraded.
Concrete seawalls are almost always inferior to well engineered earth structures. Only when space is at a premium it may be better to use concrete, but in roughly all other cases a concrete structure is more expensive and more likely to fail catastrophically. But somehow a lot of people have the "something substantial needs to be done" mindset and just don't think moving earth is substantial enough. Or at least that is my tale when I see the pictures. Maybe someone knowledgeable on the local situation can chime in on why concrete was chosen?
New Orleanian here - the areas in the article are generally on top of swampland and structures sink/erode quite substantially. They’re also outside of the levee protection zone which are primarily earthen levees. When following the road all the way to the end[0] roughly halfway it’s a real trip when you pass the massive concrete structure with a flood gate and suddenly see water bordering each side of the road. It’s also quite dystopian the amount of giant oil facilities that you pass by.
There are non-earthen levees in the city as well. For instance in the 9th ward. These are the levees that failed during Katrina. It’s the Army Corps of Engineers that constructs these levees and have become more complex (better?) over time; imagine an upside-down “T” structure buried in the ground.
If I had to guess, I suppose the reason may be that it’s because they’re outside the protection zone, and so, when it floods (not if) their infrastructure would be surrounded regardless. Also, a concrete structure surrounding only their plant I assume is orders of magnitude cheaper than moving the amount of earth it would take to build 100+ miles of earthen levees.
I had the privilege of rocking up in NOLA in a sodding huge cruise ship some years ago after whizzing across the Atlantic. I am well aware that it wasn't the "greenest" action I have ever performed.
It takes nearly a day to crawl up the river M from the Gulf of Mexico. A 18 deck monster at around 180,000 tonnes has to take it easy to avoid damaging the levees with its wash, scouring out the river bed etc. At one point, over the course of 45 minutes, our captain decided to overtake a tanker (showboating). A few minutes later we had to park up in a herringbone formation to wait our turn to dock, which took several hours.
I think it is around 70-80 miles from the sea to NOLA. From 18 storeys up a river as huge as the Mississippi still looks huge. The levees don't look very large though from up there though, they look very flat and fragile.
I studied Civil Engineering in Plymouth (Devon, not MA) and that trip on a cruise ship gave me quite a perspective on engineering works and nature.
@pjot - if you get a chance, take a run up the Mississippi on a really big ship. Its quite an eye opener.
I've designed similar structures locally. Earthen, steel, and RC.
There isn't a single reason for RC, but the biggest reason is that our local soil sucks and good soil to make 'well-engineered' earth structures is a limited resource.
Additionally, there's differences in engineering philosophy between public-works and the oil field (I do both), and it's probably the opposite of what most think. Especially wrt capitalization/ finance. Almost nothing is done cheapest, let alone cheap in the coastal oil field.
Oil wants it done for a known cost, even if higher up front, to have higher certainty in long-term risk/ or lower maintenance costs. (Also soil takes months longer to settle, and time might be big money, depending on the project.)
If that higher cost tanks the project numbers, fine; they have 100 other projects lined up to make that IRR without resorting cost/corner-cutting.
Other thoughts:
Stone that is suitable for armoring earthen structures isn't sourced locally. No mountains. Has to all be barged in.
And still wouldn't survive the constant battering of wind/waves (in both a long-term seasonal sense, as well as during an acute storm event) as well as concrete.
Subsidence of a pile supported concrete structure will match the adjacent pile supported facilities, and be minimal compared to an earthen structure, which will also have expected settling on top of subsidence.
Floodwalls can double as containment berms, and that adds many design considerations not typical for stand-alone flood structures, including chemical resistance and fire suppression.
But even something as simple as grass cutting might tip the scales. Lots of heli- or boat-only access facilities, and grass needs to be cut at least once per week during summer here. Maintaining grass/earth isn't necessarily cheaper when your yard guy needs a stack of govt twic/osha cards, a private ferry ride out, and probably transport to a private dock a few hours from town.
All of which just barely gets into the logistics involved in the industry.
>more likely to fail catastrophically
Maybe catastrophically, depending on how you want to define it, but less likely to fail overall. Concrete is more likely to fail in a predictable manor.
Even the Katrina concrete/steel 'floodwall' failures were actually soil failures, not RC or steel ones.
Thanks for the insights. That cutting the grass would be a huge cost did not occur to me but with enough red tape I see that could be the case.
Even though soil failure is the direct cause, if that fails the structure has failed. The reflex of adding more concrete does not always help. A hard, vertical structure is basically a concentrator for both currents and wave energy. So you need a huge scour protection or else the wall will only work very temporally. And a narrow structure is more susceptible to piping (where water finds a path under the structure and then erodes that away). This is of course also a soil failure, but unless you are building a boat you have to interface with the soil somewhere. And that is usually where your structure will fail...
I wouldn't blame the customer. If you put a pile of meth all over the food in a cage for a rat, its not like its the rats fault for becoming an addict or that they have any choice in the matter not to consume that meth. And if the rats start demanding meth are you going to point to the rats and blame them for being addicted or are you going to wise up and realize its inevitable given the setup?
To put it more simply in the words of Henry Ford, you can buy a car in "any color the customer wants, as long as its black." You don't get choice in the market place.
Humans have agency and self control IMO. People can and do regulate their behavior all the time.
I Feel like viewing them as rats without agency is extremely cynical, but also self contradictory. If we are all rats then let's act like rats and simply act on our most base desire. If you think people should try to do anything otherwise, then you admit that they have agency.
The market doesn't force you to buy a black Ford any more than it forces you to buy an F-350 with a lift kit and update the engine to roll coal. People choose to buy a car because it offers convenience, prestige, and they think it'll be better than not buying a car
I agree that it’s not the customer’s fault for buying and using what is offered to them. Furthermore, it’s not the producer’s fault for supplying it - after all, they are merely accepting money that is offered, acceding to demand. Spinoza figured it all out a long time ago.
So “safe supply” of drugs (meth) in your example, absolutely doesn’t work and will only get more people addicted? I mean, I don’t disagree but there is a significant amount of people who are pro safe supply
One of the silliest things I have seen them doing is trying to refreeze parts of the tundra to stop oil pipeline issues. Literally trying to solve the issue they have a hand in causing.
But so long as it is profitable combined with globalized game theory of resources, this will continue far longer than seems rational.
>To safeguard the pipeline from possible collapse, the pipeline operator, Alyeska Pipeline Service Company, was granted permission earlier this year by the natural resources department to construct the passive cooling system to arrest the thaw of permafrost that is essential to locking the supports in the ground and keeping the slope from slumping or sliding. Alyeska is installing approximately 100 free-standing thermosyphons 40 to 60 feet into the ground. Construction is expected to take 120 days and will also include a three-foot layer of insulating wood chips atop the permafrost.
If you're interested in the dynamic in this area of the country, I highly recommend the 2022 game Norco[1]. It's really more of a piece of literature than a game, and it tries to capture the dynamic of the folks who rely upon a similar plant in LA for their livelihoods.
(At the risk of overselling a point-and-click game, I'll literally buy it for you if you're on the fence about it. I thought it was that good).
I really need to play this game. I kept an eye on it while it was in development. It is so surreal to see a game named after the shithole town I grew up next to.
It's funny how the article portrays this as a key driver of climate change, when in fact natural gas displacing coal has significantly _reduced_ US carbon emissions over the last 20 years!
Natural gas has about 5% impurities other than methane. There's no need to change standard terminology when discussing energy.
Countries who use coal have even more emissions. 20% of US power generation comes from coal even now. More natural gas now, displacing coal, means less total emissions, even ignoring the particulate and mercury pollution from coal. So right now, natural gas reduces CO2 emissions!
Judging by the freely trafficked drone footage there is no "Animal Enterprise Terrorism Act" style protection for the fossil fuel industry in LA. Seems like the industry's lobbyists are just a waste of money :) One can also wonder whether it is a pure sea wall or a security measure against protesters or say people seeking refuge when displaced by some future flooding, etc. I mean it looks like a setting from some cataclismic movie.
Readit News
The problem with those "once-in-500 years" figures is that they are based on historical data - and climate change is rapidly invalidating that data. Climate change doesn't mean it's 1.5°C warmer year-round, or the sea level is 20cm higher worldwide: it means weather becomes more more extreme. What was a "once-in-500" event a few decades ago might turn into a "once-in-25" event a few years from now. We are already noticing those changes in day-to-day life!
Climate change effects are already being included when calculating wind and wave loading in many codes.
The real issue is that engineering codes use frequentist methods which make it hard to consider uncertainty, which often makes it unclear what the real safety factors are. This issue is being solved by using probabilistic engineering techniques, and in future, more sophisticated causal inference.
Those thresholds and definitions are based on the data record, and already encoded into regulation and a 100 years of construction.
What we see instead is Regulators simply increasing the requirements from a X year storm to a 2X year storm, and leaving the definitions. This is what I have seen with the California building code
Adjusting how you call the storm doesn't make the wall bigger: that's the problem. (It also makes their statement untrue in the present day, regardless of if it was true when the wall was designed.)
Dead Comment
A "100 year flood" implies there's a 1-.99^30 or a 26% chance of happening over the life of a mortgage.
I always feel like if it were phrased in that way people would grasp the concept better. Same idea holds for any X and Y.
Obvious who knows probability and who's a PE, plus various levels of self-awareness. Otherwise intelligent ppl taking terms at face value that are actually terms-of-art / industry lingo. And sometimes grossly misapplying such terms.
And that's before you even get into politics/ ideology, should you want to judge such things.
It's a 6d personality/intelligence grid.
Throwing 100 interviewees into a hypothetical thread like this is the closest I can think of to the perfect early round hiring process.
Those of us who understand probabilities immediately recognise that even assuming the base-line probabilities are correct, this will occur far more frequently than once in 100 years.[2]
And of course, the probabilities require a known historical distribution, which itself changes over time (climate change being only one of multiple factors). It is possible to make inferences based on the observed rate vs. intensity or magnitude of events. In many cases these follow an inverse-log relation, such that order-of-magnitude greater intensity events occur with an order of magnitude less frequency. Tracking the more-frequent, lower-intensity incidents actually gives a good proxy for how often higher-intensity events will occur.[3]
________________________________
Notes:
1. "The 100-Year Flood" <https://www.usgs.gov/special-topics/water-science-school/sci...>
2. A 1% probability event has a 99% probability of not occurring. For a period of time, raise 0.99 to the power of the periods occuring. Over a 100 year period, that's 0.99^100, or a 63.4% chance of no such events occurring. For the probability of k occurrences over n periods you'd apply the binomial distribution: <https://en.wikipedia.org/wiki/Binomial_distribution>.
3. This is a relationship which applies to a whole host of events, and is very frequently observed in general physical phenomena. Asteroid impacts, earthquake intensities, volcanic eruptions, storms, wildfires, terrorist attacks, and the like.
There are well established probability distributions for these things, so you're really just solving for which published curve and maybe a magnitude multiplier and seeing where your data fits.
Also there's uncertainty baked-in and accounted for at every step of the engineering design process.
Eg. Geotechnical engineers love to calculate 6 digits to 4 decimals then throw in a 400% factor of safety.
Not to worry, that was taken into account when they came up with the 500-year naming scheme.
Sure it sounds like 500 consecutive years, but it's really a 1 in 500 chance of absolute devastation every year.
How bad was the devastation?
Approximately 5x as bad as the ones where it's only a 1 in 100 chance of striking every year, naturally.
1 in 500 year storm is a one-year probability of 1/500, based on now.
There is no implied or expected future change that needs to be considered. That's already baked into selecting the design-storm-interval of 1 in 500 vs 1/250 or whatever else.
A 1 in 1000 year event need not be, and likely won't be, the same/valid probability in the year 3024. Or even 2074. And that's OK. The engineers know that.
It's more likely to be based on historical data that as of now is outdated and unreliable
There are non-earthen levees in the city as well. For instance in the 9th ward. These are the levees that failed during Katrina. It’s the Army Corps of Engineers that constructs these levees and have become more complex (better?) over time; imagine an upside-down “T” structure buried in the ground.
If I had to guess, I suppose the reason may be that it’s because they’re outside the protection zone, and so, when it floods (not if) their infrastructure would be surrounded regardless. Also, a concrete structure surrounding only their plant I assume is orders of magnitude cheaper than moving the amount of earth it would take to build 100+ miles of earthen levees.
[0]: https://commons.wikimedia.org/wiki/File:Venice,_Southernmost...
It takes nearly a day to crawl up the river M from the Gulf of Mexico. A 18 deck monster at around 180,000 tonnes has to take it easy to avoid damaging the levees with its wash, scouring out the river bed etc. At one point, over the course of 45 minutes, our captain decided to overtake a tanker (showboating). A few minutes later we had to park up in a herringbone formation to wait our turn to dock, which took several hours.
I think it is around 70-80 miles from the sea to NOLA. From 18 storeys up a river as huge as the Mississippi still looks huge. The levees don't look very large though from up there though, they look very flat and fragile.
I studied Civil Engineering in Plymouth (Devon, not MA) and that trip on a cruise ship gave me quite a perspective on engineering works and nature.
@pjot - if you get a chance, take a run up the Mississippi on a really big ship. Its quite an eye opener.
There isn't a single reason for RC, but the biggest reason is that our local soil sucks and good soil to make 'well-engineered' earth structures is a limited resource.
Additionally, there's differences in engineering philosophy between public-works and the oil field (I do both), and it's probably the opposite of what most think. Especially wrt capitalization/ finance. Almost nothing is done cheapest, let alone cheap in the coastal oil field.
Oil wants it done for a known cost, even if higher up front, to have higher certainty in long-term risk/ or lower maintenance costs. (Also soil takes months longer to settle, and time might be big money, depending on the project.)
If that higher cost tanks the project numbers, fine; they have 100 other projects lined up to make that IRR without resorting cost/corner-cutting.
Other thoughts:
Stone that is suitable for armoring earthen structures isn't sourced locally. No mountains. Has to all be barged in.
And still wouldn't survive the constant battering of wind/waves (in both a long-term seasonal sense, as well as during an acute storm event) as well as concrete.
Subsidence of a pile supported concrete structure will match the adjacent pile supported facilities, and be minimal compared to an earthen structure, which will also have expected settling on top of subsidence.
Floodwalls can double as containment berms, and that adds many design considerations not typical for stand-alone flood structures, including chemical resistance and fire suppression.
But even something as simple as grass cutting might tip the scales. Lots of heli- or boat-only access facilities, and grass needs to be cut at least once per week during summer here. Maintaining grass/earth isn't necessarily cheaper when your yard guy needs a stack of govt twic/osha cards, a private ferry ride out, and probably transport to a private dock a few hours from town.
All of which just barely gets into the logistics involved in the industry.
>more likely to fail catastrophically
Maybe catastrophically, depending on how you want to define it, but less likely to fail overall. Concrete is more likely to fail in a predictable manor.
Even the Katrina concrete/steel 'floodwall' failures were actually soil failures, not RC or steel ones.
Even though soil failure is the direct cause, if that fails the structure has failed. The reflex of adding more concrete does not always help. A hard, vertical structure is basically a concentrator for both currents and wave energy. So you need a huge scour protection or else the wall will only work very temporally. And a narrow structure is more susceptible to piping (where water finds a path under the structure and then erodes that away). This is of course also a soil failure, but unless you are building a boat you have to interface with the soil somewhere. And that is usually where your structure will fail...
Deleted Comment
As far as their customers take them :)
- sent from my iPhone which was delivered to me via fossil fuels
To put it more simply in the words of Henry Ford, you can buy a car in "any color the customer wants, as long as its black." You don't get choice in the market place.
I Feel like viewing them as rats without agency is extremely cynical, but also self contradictory. If we are all rats then let's act like rats and simply act on our most base desire. If you think people should try to do anything otherwise, then you admit that they have agency.
The market doesn't force you to buy a black Ford any more than it forces you to buy an F-350 with a lift kit and update the engine to roll coal. People choose to buy a car because it offers convenience, prestige, and they think it'll be better than not buying a car
But so long as it is profitable combined with globalized game theory of resources, this will continue far longer than seems rational.
https://www.scientificamerican.com/article/thawing-permafros...
>To safeguard the pipeline from possible collapse, the pipeline operator, Alyeska Pipeline Service Company, was granted permission earlier this year by the natural resources department to construct the passive cooling system to arrest the thaw of permafrost that is essential to locking the supports in the ground and keeping the slope from slumping or sliding. Alyeska is installing approximately 100 free-standing thermosyphons 40 to 60 feet into the ground. Construction is expected to take 120 days and will also include a three-foot layer of insulating wood chips atop the permafrost.
(At the risk of overselling a point-and-click game, I'll literally buy it for you if you're on the fence about it. I thought it was that good).
[1] https://store.steampowered.com/app/1221250/NORCO/
Countries who don’t rely on methane gas (there’s no need to call it natural gas) have substantially lower co2 emissions.
So yes methane gas is a big driver of climate change.
Countries who use coal have even more emissions. 20% of US power generation comes from coal even now. More natural gas now, displacing coal, means less total emissions, even ignoring the particulate and mercury pollution from coal. So right now, natural gas reduces CO2 emissions!
https://en.wikipedia.org/wiki/Gulf_Intracoastal_Waterway_Wes...