I need information about underground systems.

I tried researching but I didn’t find much. My book takes place in an underground setting beneath the city. I’m not well-versed in how underground systems of pipes and cables and tunnels work, don’t even know all the types that exist.

What type of cables run underground and how huge can they get? Do cables have tunnels specifically for themselves?

Are sewer and rainwater tunnels designed to never ever mix?

Where do sewer tunnels actually go? (I hope it’s not the ocean) Do they just run for miles until getting to a processing plant?

What other man-made tunnels are there underground (excluding war shelters)? Such as maintenance or something.

Could be the way my computer is set up but just look up “Underground city” or “Pipe lines”

Where is it located and how deep theres literal levels to this shit

Same thing

septic tank, ocean, lake, or river depends where you are

Broad question what function are you seeking

Some underground tunnels can be massive - and can literally be as expansive as the city above ground.

In most cases, yes. It would depend on where you live though - some areas might not have planned the tunnels well and the two substances might mix as a result of that.

Again, it depends where you live. A septic tank or a processing plant, or perhaps a body of water. It really depends.

There are some tunnels meant for living (beds, kitchens etc), some are made to escape, some are simply a route of passage. Sometimes there might be an abandoned subway system etc.

Ooh I’m remembering a documentary that might help you. https://www.bing.com/videos/search?q=documentary+on+underground+ny&&view=detail&mid=6C53EEBDA1DCB659E71E6C53EEBDA1DCB659E71E&rvsmid=9717C289BAF3E49BA2F19717C289BAF3E49BA2F1&FORM=VDRVRV

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You also get internet cables underground (and under the sea). In the past some places have lost internet access when sharks have bitten through them.

Thanks a bunch!

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I’ll just answer this real quick because I’m in a pretty modern city where this was poorly designed. The tunnels don’t technically mix, but the stormwater drains are designed to overflow into the sewers if they breach capacity in a storm. Then you get sewage flooding into the streets, into the rivers, into the lake…

And this is a major city in a first-world country, mind you, designed less than two hundred years ago.

Depends on the quality of the system. Some go straight into waterways, resulting in some of the most polluted waterways on Earth. Some small ones run into underground septic systems or biological greywater systems, which don’t really ‘go’ anywhere. Some run for miles to a water treatment plant.

Subways, maintenance tunnels, natural cave systems (if you have limestone bedrock), basements of condemned buildings, sewers, stormwater systems, overflow/backup tunnels, aquaducts in really ancient cities, catacombs, tombs, mines, tunnels for any cable/pipe/other linear system that needs monitoring and maintenance, old parking garages (if applicable), cellar systems, ventilation systems, geothermal air ducts, underpasses for people or wildlife, escape tunnels (some old mansions have them), tunnels intentionally connecting buildings… I could probably go on, but that’s probably enough, hey? :slight_smile:

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This doesn’t specifically address your questions, but there is an enormous tunnel complex under Paris. Paris it turns out is on top of large lime stone deposits. Naturally the residents quarried very extensively under the city to build the buildings of the city. In the early 19th century the streets began to cave in. To deal with this a program of mapping out and reinforcing these tunnels was started. (They also used it as an opportunity to redesign and rebuild large amounts of the city.) The program of reinforcing the tunnels continues to this day. They even give tours.

Sometimes they do exactly that. The outlet is usually several miles offshore to prevent any effect on beaches/people living on the shoreline.

Another major part of sewer systems are pumping stations, which are fairly common in cities with flat or unstable terrain, where the sewage needs a bit of motivation to get to the treatment plant.

Water and gas mains are probably the major ones to worry about.

Yep, also lots and lots of skeletons under Paris in the catacombs! I went on a tour there; most of it is locked off because it’s so big and they don’t know how safe it is, but… it’s a lot of bones (6 million people, I think?). There are so many bones that they’ve arranged them into shapes and things. https://www.atlasobscura.com/places/catacombes-de-paris has some pics and a fun anecdote.

I actually had to look this up myself because I have a story with a city in ruin and they have to get their infrastructure up and running (electricity, sewage, plumbing, etc.)

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Found this really fast.

I think it really depends on how big your city is, though. Also, subway tunnels… if the city has them.

This is also a really interesting article (I love doing this kind of research):

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