28000 year bunker conditions.

[halfeye]

Eventually you still end up with an equilibrium of mostly nitrogen, unless the leaks allow a significant draft to pass through the enclosed space. The main difference is that with slight leakage the final equilibrium is at more or less atmospheric pressure.

Much like a very large version of an unvented chain locker on an ocean freighter, say.

Well, yes, if leaks is all you get. 3 psi is 144*3 pounds per square foot, 3*144*9 pounds per square yard, you need a very strong structure to deal with that on top of the weight of the material above it.

[GeoffWatson]

It's 40k, so bull**** ancient technology is 100% fine. No point trying to be realistic.

[Telok]

It's 40k, so bull**** ancient technology is 100% fine. No point trying to be realistic.

Well its really Dungeons the Dragoning 40k 7e 1.6, which is an insane mechanical & thematic mash up of D&D, 40k, Exalted, Werewolf, and Vampire... to start with. For my game some Battletech, Shadowrun, Paranoia, Car Wars, and Ogre are sneaking in. Considering trying to work in some Pendragon too.

[Eldan]

I Mean, if it's 40k, I would really just go with "don't bother". 10k year old technology survives all the time in 40k. Even 20k year old technology is only rare because people blew it up or lost it, not because it break down. And if we bring in eldar and necrons, we have tech that is millions of years old with only marginal problems.

Just slap some "it's mechanicum/DaoT tech, it still works" on it, done.

[Tyndmyr]

If we're talking about things that "humanity has dug up," I would point out that wooden implements up to ~400,000 years old have been found; frequently, such things have been preserved not in spite but because of the presence of water.

There are weird exceptions, yeah, like being frozen in a glacier or something, but in the context of an old bunker, water would generally be extremely detrimental. I don't actually know of anything wooden being found that long ago, but generally speaking, extremely ancient wood is preserved by being fossilized, and is now stone in practice.

That lasts, but calling it wood is no longer really correct. I guess if you want to have seepage and fossilization of tree people or something, that might be kinda cool, but it definitely doesn't play well with any equipment still functioning.

The thing about oxidation is that it needs oxygen, and if everything is off then that will not be being renewed. If there is anything large and more prone to going rusty it will consume a huge amount of oxygen in a couple of decades*.

Roughly 4 grams of Oxygen for every 9 grams of iron. At standard modern oxygen concentrations, you're at around 21% oxygen, or 37 grams per cubic foot. Any average room would, even if perfectly sealed, contain enough oxygen to completely rust many pounds of metal. Unless flushed of oxy, this isn't a significant limitation.

It'll stop at some point, sure, and that point is long before the time expires, but enough rust will have surely happened to have destroyed any usable machinery.

You may still have slight leakage after that point and a slow continuing rate of degradation. Honestly, gamers probably won't expect perfect stuff here, the gold coin still being fine but the machinery being rusted up will feel right. You don't have to get deep into the math of it.

If you have some perfect sealing mechanism, a nitrogen flush of all atmosphere would probably be your most realistic preservation method. This may present breathing difficulty for the PCs.

I Mean, if it's 40k, I would really just go with "don't bother". 10k year old technology survives all the time in 40k. Even 20k year old technology is only rare because people blew it up or lost it, not because it break down. And if we bring in eldar and necrons, we have tech that is millions of years old with only marginal problems.

Just slap some "it's mechanicum/DaoT tech, it still works" on it, done.

That's also fair. That genre just really isn't super hard science. In there, you toss in some random oddities to build mystery or whatever, but the science behind it is almost entirely handwavium.

[Aeson]

I don't actually know of anything wooden being found that long ago, but generally speaking, extremely ancient wood is preserved by being fossilized, and is now stone in practice.

https://en.wikipedia.org/wiki/Clacton_Spear

https://en.wikipedia.org/wiki/Sch%C3%B6ningen_spears

in the context of an old bunker, water would generally be extremely detrimental.

The important bit for preserving things tends to be getting an anaerobic environment, not keeping things dry, and a tunnel-accessible 28,000-year-old bunker with internal battle damage is very likely to be flooded - especially if it's a bunker meant to protect against high-tech weapons of mass destruction, because that's almost certainly below the water table and therefore pumps and seals are required to keep water out given that the planet it's on is Earth-like. Per the original post, the machinery associated with the bunker ceased functioning at most a few thousand years after the bunker was abandoned, there's internal battle-damage including holes in walls (which suggests that the interior face of the exterior walls of the bunker is likely cracked and cratered in at least a couple of places, and possibly even completely penetrated depending on how exactly the attackers got into the bunker), and there's at least one access point to the bunker which the player characters are able to use despite the bunker's machinery having failed (suggesting that it's not that well sealed). Even if the exterior walls of the bunker aren't compromised, there's the issue that that the access point to the bunker would need to be able to exclude the water that filled the tunnel outside of the bunker over the past 28,000 years, but unless your seals are made of some kind of long-lived supermaterials your best-case for when the seals failed is probably around the same time that the machinery did.

[Telok]

Well the spoilered bit had more. In short there"s a natural cave a fair way up a mountain, above the frost line. That's partially blocked at the end but leads to a cave comex that goes down a km or so. Then you get the bent up ley lines that dump the bottom of that to well beliw freezing (used to be the tunnel kept going to the surface but that part collapsed). There's where a meter or three ice plug is sealing the access tunnel. The tunnel from there down is around 50km long and another 15-20 km down (I think, would need to check the file).

I'm not sure water tables go that far down under mountains. I know on coasts they'll be near sea level even if your cave is a mile deep, but I'm not sure about deep inland mountain ranges. Anyways, the magic ****ery done to run the power source puts part of the bunker (mostly the freight elevator & stairs) and the rest of the tunnel up to here well below freezing. And it's a sharp temp curve too, like 25 degrees C over about 2 meters distance. Realized that I should justify the ice plug I wrote before I started questioning stuff and the magic power generator is a sufficient excuse.

The access tunnel isn't that big. They mostly just needed it to open an area to put up a beacon to teleport stuff down to. I'm thinking 2 or 3 maybe 4 meters diameter max. But it is straight & smooth.

[MetroAlien]

I didn't quite get the supposed "biome" for this bunker...
You say it's inside a mountain.
Is it an icy mountain, a-la Alps/Himalayas?
A desert mountain, a-la Petra in Jordan?

Of course, over 28,000 years the climate may change drastically.
An entire ice age could have come and gone.
The mountain will still be there and have the same shape, but its surface landscape could change throughly.

I think by far the biggest damage done by time would be to the entrance.
Being mere mortals, we can't really appreciate how looooooong a time 28,000 years really is.
The amount of weathering and erosion may render the entrance area unrecognisable from the old days. One might not even identify it as a bunker looking from outside.

Small rivers or even lakes or entire glaciers could have come and gone in that time, never mind earthquakes, avalanches, etc...
There would be enough time for a forest to grow and wither/burn down entirely.
Some animal species could make the entrance area its permanent home, and might even evolve unique traits to fit its lifestyle around the bunker in some way.

Never mind the animals, an entire civilisation could have reached its zenith of development and gone extinct in that timeframe.
There could be hundreds of monuments, a-la Parthenon, Pyramids or aforementioned Petra, from a lost culture that revered the bunker as a home of the gods.
Said culture could even be old enough to be completely unknown to historians, if the area is isolated for some reason.

For example, even to this day, there are still remains of previously unknown cities being discovered in central Asia that were until now absent from academic historical narrative, and those are merely a few thousand years old...

To be honest, unless the entrance is specifically designed to withstand millennia of erosion, I doubt it would remain sealed.
A puny 30ft door is nothing against cumulative thousands of tons of ice and/or sand that would lash at it repeatedly over aeons.

If the door is in a tunnel, the tunnel could erode until the door is outside. And if the tunnel is too long to erode completely, it would likely cave in.
This would naturally seal the bunker, but after the cave-in had been settling in for literally longer than your in-game civilisation existed, it would take some serious archaeological efforts to even realise it's there, never mind uncovering it.

If the entrance is "open" (relatively speaking), only the first few "levels" of the bunker could be compromised.
But after that, the "compromised" levels would protect the lower levels. It's the same principle where an iced-over lake protects the fish inside from further cold.
In fact, it could be possible that already the 2nd "level" is mostly intact. But the topmost level is extremely unlikely to be free form invasive natural processes.

[NichG]

Tectonic plates move ~0.6in a year, meaning that the rock around the bunker will have moved a quarter mile in that time. The shear probably wouldn't be *too* bad, but the thing may even have been rotated around by the movement of the surrounding rock by then. Especially if its in a mountain range e.g. where plates are moving past one-another.

[MetroAlien]

to be fair, mountains don't necessarily have to be on a major fault line. The fault could be small/stable enough that even 28,000 years is short, in seismic terms.
Iirc, the Urals and Rockies mountain ranges are relatively stable.

Or the plates could be pushing into each other, slowly raising the bunker ever higher off sea level.

[LibraryOgre]

to be fair, mountains don't necessarily have to be on a major fault line. The fault could be small/stable enough that even 28,000 years is short, in seismic terms.
Iirc, the Urals and Rockies mountain ranges are relatively stable.

Or the plates could be pushing into each other, slowly raising the bunker ever higher off sea level.

The Arbuckle Mountains of Oklahoma are 1.4 billion years old.

[Telok]

The Arbuckle Mountains of Oklahoma are 1.4 billion years old.

Are those the ones down by the Texas border with the highway over the top? I thought they were hills driving over them until someone ssid something and I looked at a map.

There's a bleefin road over the top. Hill.

I am an opinionated elitist bastard on cheese, chocolate, and mountains.

[LibraryOgre]

Are those the ones down by the Texas border with the highway over the top? I thought they were hills driving over them until someone ssid something and I looked at a map.

There's a bleefin road over the top. Hill.

I am an opinionated elitist bastard on cheese, chocolate, and mountains.

In geography, they're hills. In geology, they're mountains.

I mean, they're three times older than the Appalachians. They're almost twenty times the age of the Rockies, and 300 times the age of the Sierra Nevada. They are very old and very tired and want to lie down, and I can respect that.

[Lord Torath]

In geography, they're hills. In geology, they're mountains.

I mean, they're three times older than the Appalachians. They're almost twenty times the age of the Rockies, and 300 times the age of the Sierra Nevada. They are very old and very tired and want to lie down, and I can respect that.

And being old, are also exceptionally stable. A bunker carved into one is unlikely to be destroyed by tectonic action in a mere 28,000 years.