r/civilengineering • u/[deleted] • Jan 09 '25
LA Fires - Fire Hydrants Not Working
Politics aside, there’s an interview with Gov. Newsom where the reporter asks “why isn’t there any water coming out of the fire hydrants?” He doesn’t know.
My thoughts: At this point, isn’t the system completely overtaxed? There’s not enough pressure anywhere in the system because it’s likely that every fire hydrant, sink, hose, etc. is being utilized to try to put out a fire.
From a water supply standpoint, I hear that California’s water supply’s are generally low, but I’m not from California so I’m am not familiar enough with their situation to expand on that.
My question: Is the problem why there’s no water coming out of said fire hydrant an issue caused by:
A. Water pressure
B. Water supply
C. Other causes such as the hydrants and fire systems being damaged/poorly maintained
D. All of the above
I’m very sorry to hear about everything that is currently going on in LA and the surrounding metro. I hope there’s no more loss of life, property, infrastructure or community.
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Jan 09 '25
[deleted]
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u/wildwasabi Jan 09 '25
If only they could make a pump system from the ocean but all the salt would probably destroy the system incredibly fast. Best they can do is just the air drops.
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u/someinternetdude19 Jan 09 '25
They do have piping systems for salt water I bet. I assume all the coastal power plants use it, you just need good internal and external coating systems. Also chemical plants handling severely corrosive materials. But there’s added issue that if you use that salt water, nothing will grow there for years and years.
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u/Everythings_Magic Senior Bridge PE | Zero Yield Capacity Jan 09 '25
Are you sure about that last statement? a fire is tearing through the area, nothing will grow back for a whole anyway, but things will grow back. The entire are is on the coast and gets some salt air anyway.
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u/someinternetdude19 Jan 09 '25
Yes. I have horses and have a salt block in a little plastic bucket. When it rains it dissolves some of the salt and drains out. The area around it is completely dead. We’ve tried seeding and everything and nada. So now it’s just the salt block area. The ocean spray won’t make it up into the hills where the fire is.
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u/zaxls Jan 09 '25
Are you sure seawater contains that much sault tho
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u/someinternetdude19 Jan 09 '25
It has enough that in coastal areas you have to use extra robust coating systems. Idk what the actual salinity of seawater is, but I actually read a news article where they talked about not using seawater for previous firefighting efforts because it would poison the ground. And there have been issues in Florida where stagnant water after storm surges kills all the vegetation.
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u/Mat_The_Law Jan 09 '25
Water is heavy, I know firefighters personally who’ve drafted from the ocean (like last month in Malibu). It’s hard on the pumps and you get limited distance. Water trucks can do it to supply other trucks but you have limited options pumping water uphill.
Realistically a lot of wildland firefighting is not spray the wet stuff on the red stuff, it’s about cutting firebreaks, evacuating people and pets, and trying to mitigate damage. Some areas you’ll have foam/gel sprays going down on houses to help protect them, but generally at the size of the fires it’s try to steer them away from further damage and keep people safe.
Even when there are larger water supplies we’ve seen overruns in the state. More than one wild fire has overrun initial fire camps and firefighters and fire lines end up retreating. You won’t typically hear this but most fires get put out either because they burn to the see, the wind turns them back on themselves, or the rains come.
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u/TheMayorByNight Transit & Multimodal PE Jan 09 '25
I wish the media were more straight forward in reporting this and I wish people were more interested in understanding the fragility of infrastructure around them. It's not possible to force this much water down any city water pipe to put out a fire this large.
If they used several of those 3M gallon tanks in a "couple hours" each, they're moving 20-40CFS per tank.
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u/Interesting_Bug_862 Jan 11 '25
But the initial response should have been to put out the burning houses and water down all the other houses. 5k-10k homes didn't catch fire all at once.
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u/a2godsey Jan 09 '25
I explained this to my very right leaning uncle who was very hell bent on blaming Newsom, Democrats, and Biden.
If you put 5 space heaters in every room in your house and your breakers trip, who are you going to blame, the president? Democrats?
Took him a while to come up with a "huh yeah I guess that makes sense"
Infrastructure isn't designed for worst case scenario. If it was, we'd all be paying 200% taxes. Money doesn't grow on trees, it comes from the middle class. Wildfires are containable as hurricanes. There's ways to make damage mitigation better but mother nature will always prevail.
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u/Economy-Ad4934 Jan 10 '25
"I explained this to my very right leaning uncle who was very hell bent on blaming Newsom, Democrats, and Biden.
If you put 5 space heaters in every room in your house and your breakers trip, who are you going to blame, the president? Democrats?'
Bro, you KNOW they will blame them. I have family like this too, tehya re beyond reason.
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u/connoriroc PE - Thermal and Fluid Systems Jan 10 '25
That's a great analogy.
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u/a2godsey Jan 10 '25
It's pretty simple. Yeah my house could have been built with 400amp breakers that I could one day host a music festival in my backyard, but I'm never going to have to do that now am I? You can't budget for and build to a 0.001% likelihood, same as for me as a stormwater designer I'm not sizing swales, basins, pipes, etc. off of a 1000 year storm.
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u/DefaultUser614 Jan 09 '25
NPR had a story that touched on this topic this morning. Basically the person being interviewed said the hydrant system is designed to fight one or two house fires at a time, not hundreds and that they are working to refill the water towers/reservoirs for the network
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Jan 09 '25
And also, you don't want to drain every reservoir to fight this one fire, because now on top of people having their houses burned down, you have an even larger area that is facing water insecurity for the next several years.
Even if you had 30" pipes on every street, running them at max flow to fight fires isn't necessarily a good idea, especially in an area that's already stressed for water.
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u/mrparoxysms shouldhavebeenaplanner, PE Jan 09 '25
Upvotes for any NPR reference, they are my media shelter these days.
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u/A_Ram Jan 09 '25 edited Jan 09 '25
Hydrant systems are usually designed to handle 1-2 fires simultaneously per residential area and 3-4 for industrial. Industrial areas usually have their own reservoirs that can last around 2-3 hours.
From what I've seen on the news they have a lot more fires out there and it's been all burning for more than 2-3 hours, so there is no water because all water is used somewhere else.
Fire engines have pumps that increase pressure, so it looks like they are just sucking everything out of the system. They need a lot of water ~1000l/m per hydrant. for comparison a household will use 200-500l daily.
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u/Asclepius555 Jan 09 '25
I used to build models of city water systems so we could design improvements to them. As an example, for a small town in a rural area, we would consider a max flow scenario involving high demenads during peak day, peak time of year, and also a fire at one hydrant. The exact scenario we considered depends on a lot of factors. In essence, we model for a certain level of demand, based on what has happened in the past and assume it will be similar in the future. Then, we scale the number up with a factor of safety. These factors vary depending on the situation.
I would never have dreamed of modeling a water system that could handle the fire fighting needs in LA now. That would be impossible to build and maintain for any city due to the extreme cost of such a system.
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u/Grumpycatdoge999 Jan 09 '25
Insanely high demand, leading to lower water pressure. Also since water has to be pumped up to the palisades, mechanical failure can lead to local water shortages
It’s still really early of a story to say, but here’s news article from the LA times about it and people they interviewed:
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u/Mat_The_Law Jan 09 '25
Knowing what I know of the area: there’s probably a few reservoirs and associated pumps that were taken out, they’re also fairly small. They were filled prior but the ability to resupply them and maintain pressure uphill is basically not happening once the fire approaches and power is down.
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u/dgeniesse Jan 09 '25
There are many good answers to the OP question. I will add one unfortunate tid bit.
During the Paradise Fire (Camp Fire) in November 2018, the potable water was contaminated primarily due to the extreme heat of the fire creating a “toxic cocktail” of gases in burning homes. When the water system depressurized due to heavy water usage by residents and firefighters, these toxic gases were sucked back into the water pipes.
This problem is still being addressed.
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u/UndoxxableOhioan Jan 09 '25
I have to imagine LADWP has every pump working. But it won't be enough.
But know there are other issues. No doubt many of the buildings have fire suppression systems that have been activated. Even if they do not, supply lines to buildings can melt or break loose, leading to a constant flow of water. I bet a newer city has a lot of plastic pipe, be it PVC, PE, maybe even polybutylene, which made the pipes open faster in a fire.
And with all this rapidly changing use, I be the system is getting hammered. I would not be surprised if main breaks were not a contributor.
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u/Jmazoso PE, Geotchnical/Materials Testing Jan 09 '25
I can’t imagine the stress the head of water and power is under right now. She’s been on the job less than a year and came on because of her experience on the power side. They got her from PS&G. She’s a PE, but has a mechanical degree.
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Jan 09 '25
i would imagine that the system is not designed to turn on hundreds of hydrants at a time, that is an insane amount of water. its probably designed to turn on a few at a time...
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u/scott_ellis_novatex Jan 09 '25
In Australia, if you have a pool, you put a little sign on your mailbox/street front. Then the fire brigade knows that they have a local water source they can use, which helps with exactly this need for more water than can be supplied problem.
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u/Crafty_Ranger_2917 Jan 09 '25
There's a lot of moving parts.
Water systems of different sizes have varying storage requirements...think utility serving a thousand connections or one serving 50,000. With that comes different fire storage requirements. Things like 500 gpm hydrant flow for 2 hours, groups of hydrants for adjacent neighborhoods, etc.
Other end is you can't just store unlimited water. Simple water system is pump from a well, chlorinate and store in a tank. You can't leave it there for more than say a month before it builds up too many disinfectant by-products. Storage and chemicals costs money, non-disinfected water gets gross and hard to manage, etc.
Next part is moving the water. Sometimes its all gravity once you fill the tank, ie standpipes to houses. Will have backup generators for well pumps, boosters, controls and such, but burn those down and you're done except gravity flow.
So take a little system, not networked to adjacent utility, with a single 1MG tank. Might be a couple hundred homes. There is a wild fire and with only five hydrants open at 500 gpm each, water is gone in 6 hours.
Reality is many people with hoses, few houses burned and their service lines making rain, tank was already partially drained from everyone hosing down their roofs and filling tanks....might only have an hour or two of water....essentially insignificant. Bunch of variables depending on type of fire, fuel load, on and on but sometimes water just isn't going to help in a wild-fire. They can evaporate entire streams....a fire truck hose might be spitting on a bonfire.
TLDR: Public water systems are designed to provide potable water and fire suppression for normal structure fires. Wild fire = different situation.
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u/lennym73 Jan 10 '25
Factor in 10 firetrucks pumping out a couple thousand gallons per minute makes it disappear faster. I'm sure there wasn't much for water management when it started and they were trying to knock it down quickly.
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u/kloogy Jan 09 '25
This is why many military bases have dedicated fire main loops. Most cities tap the water lines to hydrants from the domestic water piping. They are not sized to handle the demand being used right now in these areas.
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u/Bulldog_Fan_4 Civil PE, PLS Jan 09 '25
Yeah way over the demand with everyone including fire fighters drawing water.
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u/These-Bedroom-5694 Jan 09 '25
I don't know at what temperature a hydrant melts, but I wouldn't put it past this fire. A damaged or destroyed hydrant can leak, causing a loss in pressure.
Water pumping stations need power. It's possible the fire has destroyed above ground electrical lines.
The water is being used faster than the pressure system was designed to support. I can't imagine the volume of water in use.
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u/a2godsey Jan 09 '25
Homes destroyed with active water supply that hasn't been shut off is a big reason why hydrants drop pressure. It's like if every tap is on full blast in your house, everything drops in pressure to compensate. Multiply that by tens of hundreds of homes and that amplifies the problem. But in times like these it's far easier to blame political parties than it is the real world problems that transcend politics.
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u/avd706 Jan 09 '25
Pex piping probably fails quickly in a fire.
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u/joestue Jan 10 '25
Every house is going to be a 3/4 or 1 inch open pipe in 15 minutes. On the order of 10 to 30 gallons a minute
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u/crazylsufan Jan 09 '25
Is anyone familiar with the fire mitigation strategies that were being used prior to these fires starting? The news wants to paint it like nothing was being done. I just find that hard to believe
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u/we8ribswiththatdude Jan 10 '25
Excellent article today in the LA Times about the water situation in Pacific Palisades when the fire started. https://www.latimes.com/california/story/2025-01-10/as-flames-raged-in-palisades-a-key-reservoir-nearby-was-offline
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u/ElegantGate7298 Jan 10 '25
Yea. This thread has taught me a lot about the limits of municipal water systems and how they really aren't suitable for fighting wild fires but having a 117 million gallon reservoir off line sounds like it could have made a difference.
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u/TylerDurden-4126 Jan 10 '25
It's really A and C with a bit of B...but it's not the regional/statewide water supply that is the new political football the uninformed want to kick around...I hate Newsom more than most, but water policy was not the cause of hydrants running dry, as many here have accurately noted.
Here is article describing an issue with an empty local reservoir that also provides comments from water system folks with accurate information https://www.latimes.com/california/story/2025-01-10/as-flames-raged-in-palisades-a-key-reservoir-nearby-was-offline
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u/we8ribswiththatdude Jan 10 '25
Are you telling me it is not the smelt's fault? /s
I wouldn't want to be the one to tell the folks whose homes are nothing but a pile of ash that there is a 117MG reservoir that was offline right up the block from them. Even if the end result would have been the same, at least people could feel like there was a fighting chance.
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u/TylerDurden-4126 Jan 10 '25
Oh those smelt ;)
But seriously, I wouldn't want to have to explain the empty reservoir to those folks either, but it would not really have made much difference if was operating at the time unless the full amount was able to be pumped on the fire within about 5 minutes of sparking
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u/Gullible_Rich_7156 Jan 11 '25
Not an engineer but I work for a large water utility and I’m glad I’m not the only one pulling my hair out every time I hear “THE SMEEEEEEEEEEEEEEEEELT!!!”
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Jan 09 '25
[removed] — view removed comment
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u/AlphSaber Jan 09 '25
Except multiple hydrants are in use already, and most likely across separate zones. It doesn't matter if you tap 1 hydrant or 5, if there's no water to draw from using multiple hydrants are not going to be able to draw flow that isn't there.
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u/PhilShackleford Jan 09 '25
This is the same as asking why buildings aren't designed for tornados or for flooding. It is possible but wildly impracticable and massively cost prohibitive.
EXTREMELY few things are designed for natural disasters. Even the ones that are designed for them (e.g. school tornado shelters) only have a small portion of the building rated for it. And even those are often complained about because of the cost.
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u/numbjut Jan 09 '25
Can they somehow put drops into the ocean or is that unrealistic?
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Jan 09 '25
That would only be realistic for fires in the immediate vicinity of the ocean... like a few hundred yards.
You're not going to be able to pump seawater through the miles of hose it would take to be useful.
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u/numbjut Jan 09 '25
I was thinking more of filling tanker trucks, obviously it would take a lot of trucks and coordination. It is really a horrible situation.
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u/rncole PE - Construction, Nuclear Experience Jan 09 '25
You pretty much can’t get enough trucks. A typical water tanker is 4,000gal; a fuel tanker (semi-trailer) is 6,000. At 150-200gpm flow (times 5-6 hoses) you’d get maybe 4-5 minutes of flow. There are mega tankers for construction sites but those wouldn’t be anywhere near where they’d be needed, and there would be potential issues with how to get it to where it needs to be.
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Jan 10 '25
Saltwater + metal is no good. Even if they were to do it, those trucks would more than likely be toast afterwards.
I realize that's pennies compared to the loss that's happening... but I don't imagine anyone is going to willingly destroy equipment that could be used elsewhere with fresh water (where available).
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u/iboughtarock Jan 16 '25
What if they used sacrificial anodes for the tanks in the trucks like on water heaters? Not saying it is a good idea at all considering how detrimental high salinity soil is, but I think transporting salt in a tanker would hardly be a problem compared to having all the salt water flow through hoses and other equipment.
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Jan 10 '25 edited Jan 10 '25
In every urban conflagration I’ve been on in my 40 year California fire career, since The Oakland Hills Fire in 91’, this happened because, when you have row upon row of homes burned to their foundations, the residential supply lines are all sheared off and free flowing, plus the draw down from use for firefighting, over taxes the system.
Then, every one gets fired up and starts blaming the fire service, the city manager, mayor, governor, etc
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u/Adventurous_Light_85 Jan 11 '25
So to get pressure in places higher in elevation you have two options. You either create head pressure with pressurized tanks, or gravity reservoirs higher up the mountain or you run pumps constantly to create pressure from the bottom of the hill. In palisades, Those reservoirs were designed for a much smaller fire event and the winds turned this into an inferno. The whole system was designed around those reservoirs creating head pressure, well they ran out if water thus no more pressure. The system was still connected to the city down the hill but it wasn’t able to give them nearly what the pressure needed was to deal with the numerous fires. I don’t know if those reservoirs have their own pumps in the hills or if they were refilled by the city mains at the bottom of the hill, but whereby er those pumps/wells were, could not keep up.
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u/BreatheDeep1011 Jan 09 '25
It doesn’t help having burning Teslas everywhere with lithium batteries taking more water to extinguish.
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u/Interesting_Bug_862 Jan 11 '25
Did anyone hear Biden's explanation? He said the utility companies turned off the power so the pumps couldn't operate which meant there was no pressure in the hydrants! I searched Palisades on Google Earth and found at least 4 water tanks up in the higher elevation and two reservoirs. One was apparently bone dry for some repair. My point is, this was a gravity system, if they did pump, I didn't see any pump buildings, wouldn't they also have diesel generators which kicked on in a power failure? Asking a general question but also, if anyone has specific info on Palisades. Was Joe spreading disinformation?
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u/Ancient-Bowl462 Jan 11 '25
Water systems are designed specifically to carry the demand of fire loads. That is the number one design requirement. With that said, knowing that this area of California is prone to fires, they should have tanks and impoundments specifically for fire events. Water districts flush hydrants on an annual basis to ensure operation and to flush stale water from the system. There is no excuse for what is happening in California. It is absolutely the fault of the governing bodies.
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u/Girldad_4 PE Jan 10 '25
E. it's a conspiracy to burn down Diddy evidence with jewush space lasers, do you not watch TikTok?
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u/mmfla Jan 09 '25
It’s not just a California problem. Water systems aren’t designed for many fire flow loads. They’re intended for single fire events. Oversizing the mains to capture a scenario like this would lead to water quality issues with stagnant water and low residuals.
But the answer to your question is D. It’s the entire system. Additionally when homes become destroyed the potable water lines break and free flow which then aggravates the demand problem.