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I'm building a town that only has access to medieval technology. Nevertheless, the town has its own sewage system that ends in a large cesspit. All inhabitants' wastewater goes into this cesspit.

Of course this means that the need to periodically empty this cesspit arises. How can this be done?

My problem is that as far as I know anyone who enters a cesspit will be immediatelly overwhelmed by fumes and unable to get out. I've read warnings in a newspaper that if someone falls into the cesspit the others shouldn't try to get there and save him, or else the cesspit will trap anyone who tries to save whoever is already there.

Pumps were known in ancient times already, so I suppose one could employ, for example, a screwpump (Archimedes' screw) to empty the cesspit's liquid part without poisoning the pump's operator?

But what about the solid parts (fecal sludge)? I suppose one cannot simply go there and excavate it with shovels?

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    $\begingroup$ Well, an Archimedes Screw would be able to deal with solid matter as well. It's sometimes also called a 'drill'. But why do you have a cesspit in the first place? Where's the live-giving river of your town? $\endgroup$ – dot_Sp0T Aug 1 '17 at 16:55
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    $\begingroup$ where are they going to empty the cesspit to? The river next door? Enemy lands x miles away? $\endgroup$ – depperm Aug 1 '17 at 17:04
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    $\begingroup$ Night soil was used as a fertilizer. There were numerous people ("nightmen") employed in collecting it and carrying away from the city and onto farmland. $\endgroup$ – AlexP Aug 1 '17 at 17:13
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    $\begingroup$ You need a poopsmith $\endgroup$ – Nacht Aug 1 '17 at 23:21
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    $\begingroup$ Using that most fundamental of medieaval technologies, the man with a shovel. $\endgroup$ – Separatrix Aug 2 '17 at 11:34
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I would suggest composting. Design the waste water routing (trenches or plumbing) so that they can feed into one of several cesspits, then change which pit is fed on an annual basis. After each pit's year of service, add wood shavings and leaves, then allow it to season for a few years until it comes up again in rotation. Just before you change the waste water routing, shovel out all of the fully mature and fertile compost and spread it around your fields.

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    $\begingroup$ Human waste compost can be dangerous due to parasites etc. Still, in medieval settings this wasn't really something people thought about. $\endgroup$ – Mołot Aug 2 '17 at 5:54
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    $\begingroup$ @Molot, good catch. I knew about the disease and parasite issues and considered including them in my answer, since the solution of cooking the mature compost over a fire as a last step cleansing is simple enough; but as you also pointed out, medieval times predate germ theory, so no one would think to perform that pasteurization. Perhaps they can add something to the young pit to make it cook hotter than standard compost; something which might sterilize it during the first year, then dissipate to allow worms and good bacteria to move in. Something the town folk would consider as ritual. $\endgroup$ – Henry Taylor Aug 2 '17 at 6:08
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    $\begingroup$ If only they will separate urine - it can be composted with plant waste for high-nitrogen, low-to-no pathogen compost. Solid waste needs temperature... On the other hand, if dried it can be simply burnt. Anyway, collecting it in several pits and letting it dry / matura is a good idea and you have my +1 already. $\endgroup$ – Mołot Aug 2 '17 at 7:44
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    $\begingroup$ @Mołot It is only really potentially hazardous when relatively fresh (first few months) - if it composts for a year it is unlikely to be any more harmful than any other compost heap (and nothing compared to the sanitation of the townsfolk themselves). Urine would likely be separated anyway - far too useful to just dump. Stale urine was needed wherever ammonium would be useful - fulling cloth, tanning hides, making dyes, making some soaps or many other useful applications. That wouldn't make much difference here anyway. Just leave it for anaerobic digestion to render it safe. $\endgroup$ – pluckedkiwi Aug 2 '17 at 19:20
  • $\begingroup$ @pluckedkiwi In point of fact, unless the donor has a kidney or bladder infection, urine is probably more sterile than the local drinking water in a mediaeval setting. $\endgroup$ – Perkins Aug 3 '17 at 23:59
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It is pretty simple, and this is actually how it was done until about 50 years ago in the region where I come from, where most of the houses had no sewer at all, but only a small cesspit. The method is surprisingly similar to the one used to clean barns...

The access to the cesspit was granted via a large manhole. Once in a while through the manhole straw was dumped to absorb the liquids and also mix with the solid stuff. A man (or more) then went into the cesspit and first mixed thoroughly the straw and removed it using a fork.

The moist straw was then used to fertilize the ground of close by farms.

Being far from sealed (there was no siphon on the toilet side, and the manhole was just wooden) there was no accumulation of toxic gases, as you could confirm by walking around the place...

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  • $\begingroup$ Yes, we had a cesspit on the farm (called a septic tank). it was at the bottom of the garden, next to the river. The top was concrete slabs, unsealed, and there was a pipe for ventilation at one corner (and now I know why). When it was deemed to be full the concrete slabs were lifted and the content was dug out and used to fertilise fields. Probably not allowed these days? Because of the ventilation it didn't smell at all. $\endgroup$ – RedSonja Aug 2 '17 at 8:32
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    $\begingroup$ @RedSonja Well... if you don't use artificial fertilisers, this is one of the main alternatives. Some "organic farms" might use human waste (though always with heat treatment to kill the bacteria) in addition to animal waste. Large-scale (waste-)water treatment plants sometimes sell the waste for profit - it'd be a huge waste to throw the waste away. But it's quite complicated when you need to take care of all the impurities that weren't there (or people didn't realise were there - e.g. lead) in earlier times. Lots of useful stuff in there, but separating it from e.g. drugs is tricky. $\endgroup$ – Luaan Aug 2 '17 at 12:46
  • $\begingroup$ around 6:50 of this video they start the section on gong farmer (cess cleaner)and continues into the next video. useful for understanding how it was done youtube.com/watch?v=va4vYnjqjfg $\endgroup$ – John Aug 3 '17 at 4:22
  • $\begingroup$ @RedSonja Cesspits and septic tanks are not the same thing. Cesspits are sealed; septic tanks are holding areas for initial decomposition of waste that then drains into the ground (at least as those terms are used in the UK). $\endgroup$ – Mike Scott Aug 3 '17 at 13:19
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    $\begingroup$ @RedSonja Think of it this way. A cesspit is just someplace (sealed, open, whatever) where organic waste is dumped. It generally has no intentional outlet, and whatever goes in there stays in there. A septic tank by contrast is specifically designed to be a bacterial breeding ground and generally seeded with cultures that will break down the expected types of waste, with the waste water and CO2 getting vented. Prior to the advent of synthetic fiber clothing, a septic tank could go several decades without needing to be emptied. (alas, polyester and rayon do not biodegrade without UV light.) $\endgroup$ – Perkins Aug 3 '17 at 23:58
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Actually, cleaning of cesspits and latrines was a well rewarded, if not we'll respected job since Medieval times to 19 century, you might want to consult this article:

https://en.m.wikipedia.org/wiki/Gong_farmer

Up to 19 century many houses in Europe had cesspool in basement, sometimes it caused wooden beams to rot and floor to collapse, as in the case of Emperor Frederik I in 1183, when he and his guests fell 39 feet down into cesspool in Erfurt Castle.

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    $\begingroup$ "sometimes it caused wooden beams to root" -- root, or rot? The former would be impressive, but I suspect you mean the latter. $\endgroup$ – John Dvorak Aug 2 '17 at 8:43
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    $\begingroup$ Rot, of course. iPhone spelling correction has some history ideas of it's own :-) $\endgroup$ – user61244 Aug 2 '17 at 13:00
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If it was dry, it is just digging out a mudpit. Good medieval work.

But if was wet they did not need to swim around in it. The medievals had dredges. They needed them to keep their ports and rivers navigable.

enter image description here

from http://www.ancientportsantiques.com/wp-content/uploads/Documents/AUTHORS/Morhange-PublGenerales/Morhange2016-HistoryPorts.pdf

At its simplest a dredge is a porous bucket or weighted rake or plate. You get it out there, let it sink, then pull it back to dry land and it drags whatever is on the bottom up with it. Repeat. You would do the same with the cesspit. It still requires someone with a shovel and a wagon or wheelbarrow but everyone stays out of the pit.

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Fumes only build up if it is sealed, we do that so that the odors aren't noticeable, in medieval times people often relieved themselves in the streets and hygiene wasn't a big thing, literally everything smelled terrible by modern standards, so not as big of a problem. Simply open up your cesspit and let it vent for a while this should take care of the worst of the deadly fumes. The people living by the cesspit aren't likely to be important enough for their complaints about the bad smell to cause any problems.

Then utilize the most common tool of the period, disposable peasants. Armed with some shovels, buckets, wheel barrows, and wagons they would definitely be able to accomplish the job. This would of course be a terrible job, prone to all sorts of diseases and ailments, not to mention the smell. This was often the job of the lowest of the low caste members of the society. Even if several peasants keel over and die in the process, just add the body to the collected material and move on.

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I would recommend a wide diameter Archimedes Screw, a pumping technology (for water) already firmly established at least 1000 years before Medieval times.

When the cess pit is built, install a stand of rocks to support the screw several feet above the bottom; there is no need to empty every last bit of it.

Nobody has to get into the pit to dig; the screw can be powered entirely by persons or (with some spooled up rope) by horses walking away, or with some wood gearing by horses walking in circles.

The screw can extend as high above the ground as desired, so the waste falls into wagons, chutes, or whatever you wish. In fact, from the article:

Archimedes screws are used in sewage treatment plants because they cope well with varying rates of flow and with suspended solids.

Archimedes_Screw

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Don't seal it and hire These Guys!

Gongfermors, Gong Farmers, Dunnykin Divers, Night men, and so on were the guys who historically did exactly this job.

The system wasn't sealed so the accumulation of gasses wasn't as much as a problem, but things were far, far from pleasant.

They would go to the cess pits and use buckets and shovels to clear out the waste products, often using boys to get into the more confined spaces.

They often worked at night. The wikipedia has a snippet of an ordinance that says they had to work after 9 at night.

As an alternate method, I remember my dad talking about slit trenches in Viet Nam being lit on fire to burn off a bunch of the nastiness, and the remains being shoveled out to use as fertilizer.

Just remember to keep it a long way away from the source of drinking water

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If you are too squeamish to dig out the old pit dig a new pit and use some of that dirt to cover the old one. Grow food on the newly available well fertilized ground.

Even the most picky of laborer will be willing to dig again in the old site when the new one fills some years later. Especially if you don't bother recording exactly where it was and just pick a convenient spot each time.

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  • $\begingroup$ Not a terrible idea, but it means re-routing all the wastewater to the new pit. If the wastewater network of channels is extensive, rerouting all of these any significant distance becomes prohibitive or even impossible if they would have to cross private land that had become developed, farmed or settled in the years since the first time these channels were created. $\endgroup$ – Amadeus Aug 2 '17 at 9:16
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    $\begingroup$ If the wastewater runs to a common canal that branches out to the several cesspool/pits, and all but one branch is blocked (until it comes time to rotate, when the block is removed from the new branch and moved to block the old) it ought to be doable. The oldest pool/pit should be dry enough that its contents could be removed and fed into a furnace. The heat from the furnace could power primitive machinery or be used for cooking, and the ash left over has no living parasites that could counter-indicate it being used as fertilizer for food crops. $\endgroup$ – Monty Harder Aug 2 '17 at 19:18
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Sewage management goes back into pre-history, with some elaborate yet efficient systems having been developed by the early bronze age. In the levant (aka biblical cities) sewage conduits ran under the streets and a fair distance out of the towns into a common dump area called a "gehenna". The city's gehenna was far enough away that it dd not need a lot of management.

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  • $\begingroup$ Indeed. Look at the cloaca maxima - perfect example of what needs to be done. (Heck, I won a free beer at bar trivia knowing what the CM is/was!) $\endgroup$ – ivanivan Aug 2 '17 at 23:50

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