Introduction: The 'Easy Empty' Composting Toilet Project: Part 1 - Ground Works

Picture of The 'Easy Empty' Composting Toilet Project: Part 1 - Ground Works

Ever since the invention of the flushing toilet in 1596, the human race has been recklessly wasting a hugely important resource and contaminating our oceans with the same. Now, at last, the technology is available for each and everyone of us to compost our faeces and get them transported to our local organic farm for recycling into valuable fertiliser and soil improver. Now is the time for us all to 'close the loop' and build composting toilets - knock down your garage and build a toilet instead. Don't feed the crabs - return the minerals and nutrients back to the land!

We ourselves have been defecating in an outside toilet here for 5 years and, yes ...... there have been problems!

The original design was really simple - a garden shed perched over the top of a 1,000 litre IBC, which worked really well except it filled up too quickly and was then extremely awkward to move from beneath the shed.

Version V1.02 is a significant upgrade from the previous design and needs to cater for 5 permanent residents and dozens of summertime visitors, so the system of removing the IBCs must be improved. In this design the IBCs can be easily removed without damaging/demolishing the shed.

Composting toilets are a really great idea as long as they can be emptied easily without getting oneself covered in human faeces during the process. Whatever container the faeces end up in, that container needs to be able to keep the waste from contaminating the environment and be able to be easily transported. The great beauty about IBCs is that they are almost purposely designed for exactly this kind of job - they are water tight, easy to transport and once away from the dwelling can be left in the corner of a field to 'mature' into useable compost.

Step 1: How It Works

Picture of How It Works

Version 1.02 will have the same 'shed above a tank' principle, but will have a large, flat and smooth concrete pad at ground level on which the IBCs will be made to slide backwards and forwards. If this sounds a bit wacko, then read on:

When the IBCs are empty, they are fairly light weight and can be rolled and pushed around on smooth concrete by one person alone. When they are full, they can still be slid around, but require a tractor to do so. If, for example, there is a full IBC at the back of the structure, it should, in theory, be able to slide forwards by means of chains attached to the tractor as long as the concrete slab is built properly.

Everything is dependant on the slab: It must be smooth, flat, slippery and strong. Slippery? How do we make concrete slippery? Answer: oil.

You may think that this design is a bit risky, being dependant on a full IBC slip sliding along a concrete slab, but, in a previous lifetime I worked in places where full IBCs were actually deliberately pushed along slippery, oily, concrete floors by fork lift trucks - so I know for a fact that it can be done.

Step 2: Tools, Materials and Machinery

Picture of Tools, Materials and Machinery
  • Concrete mixer
  • Shovel
  • Spirit level
  • 4" x 2" timber x 20m
  • 4" x 4" Metal post holders
  • 15 bags of cement
  • 3 large ton bags of 12mm chippings and dust
  • Duck boards
  • Large soft bristled brush

Step 3: Procedure

Picture of Procedure

Essentially, this is just a concrete slab with 6 metal post holders positioned around the outside, but there are a few key points to remember, especially on how to get a nice flat smooth finish in one go without having to put on a second layer:

  1. Remove the excess soil and dump it somewhere appropriate. The slab needs to be slightly bigger than 2 x IBCs positioned side by side. I made the slab 2,200 mm wide and 3" thick.
  2. Get the plot roughly level, mark out the holes, dig the holes and put marker sticks in the holes for the metal post holders. Use a mini digger to dig the holes and level the plot and don't do it when the ground is too water logged.
  3. Check the levels once more, check that the diagonals are equal and, using a piece of 3" x 3" timber, gently knock in the 6 metal post holders. Don't put the holders in too far as the timber needs to be kept nice and dry above ground level.
  4. Pour in concrete around the posts and allow 12 hours to cure.
  5. Build a wooden frame from 4" x 2" and screw it together. Don't use nails as it needs to be disassembled without disturbing the concrete.
  6. Uses pieces of scrap wood to shutter off any gaps where the concrete would escape the frame.
  7. Pour in the concrete from the back and start tamping it with a 2m length of 4" x 2" .Tamping the concrete is a 2 person job. Tamping is performed by jiggling the 4" x 2" up and down just at the surface of the concrete and simultaneously moving from side to side.
  8. When the frame is full, finish the tamping and leave the concrete until it starts to cure. Remove the 4" x 2" before the concrete is 100 % cured or it may not release.
  9. To get a smooth finish, use a soft bristle broom to brush out any imperfections on the surface before the concrete is fully cured. Test a small section first as if the concrete is too soft, the broom will do more harm than good.

Step 4: Next Task

Picture of Next Task

So that's the ground works finished. The concrete needs to be left to cure for at least 5 days before IBCs can go onto it. Small children and dogs are OK though.

The next task is to start building the wooden part of the structure ..... Part 2 is here:

https://www.instructables.com/id/The-Easy-Empty-Composting-Toilet-Project-Part-2-Su/

Comments

oragamiunicorn (author)2017-03-06

at a push you can tamp with one person by using a piece of wood slightly longer than the distance between the sides, then cutting out the bottom corners (effectively making a capital T with a very, very wide vertical) so that when you wiggle the tamper it is held in place. So long as you don't let the tamper slip diagonally it works well and keeps a uniform, level top. also you can hold the planks for the sides in place with ratchet straps for easy release.

blenderbender (author)2016-05-31

Perhaps this being just Part 1, I should wait to comment, but filling up an IBC with human waste does not compost make. Do you address the "composting part" in future episodes? Thanks!

Yes, I will definitely remember to talk about the composting part of it. Basically, the IBC must be kept free of liquids eg urine and, when full, aerated with a fan or natural means to reduce the moisture content and it then composts from the top downwards. I've already got one full IBC here and this is what is happening as we speak !

Also remember that in the US you HAVE to connect to sewer line, but not necessarily connect EVERYTHING up to it. It is so ridiculous that we allow contamination on a large scale level, but don't we dare maintain our own solid waste through educated engineering!

In some countries it's customary to poo wherever you like on the ground. This gadget could encourage them to stop doing that.

JON-A-TRON (author)2016-06-26

Great instructions on pouring a slab. Looking forward to part 2!

Thanks Jon - Part 2 has just been published a few hours ago!

tjdux (author)2016-05-31

That's true. A pallet jack would be easy solution for that. Unfortunately you can't build one as cheap as you could buy one.

tjdux (author)2016-05-30

Would it be difficult to attach wheels or just lay down peices of metal pipe to roll the IBC across? It would sure be a mess if one of those IBC failed and broke while pulling it. You would be up you know what creek lol. I know they are tough and can be pulled but I worry for your sake that after years of use they may wear down and break.

I worked at a brick factory where they had essentially train track rails built into the floor to move huge cars of brick through giant kilns. What about a rail system and a rail car to set the IBC on to pull it through the system and remove with your pallet forks at the end? I realize that's a lot to engineer and buy and construct but it should hold up to the test of time well.

Good luck with the building. I wish I could get on board with this waste reuse method but here in town it wouldn't be allowed.

Tecwyn Twmffat (author)tjdux2016-05-30

Thank you for your comment tjdux - much appreciate the ideas.

I did think about metal pipes to roll under the IBCs and also concreting in metal rails, but thought both ideas too complicated. I know after several years of hard labour the IBCs do break, particularly at the hands of bad fork lift drivers.

I would not pull the IBCs from the front rails, I'd put a chain round the outside of them so there's little chance of them breaking except getting a bit squashed!

I guess you must be in the USA if you can't do this in a town house? I think it could be done in UK towns.

tjdux (author)Tecwyn Twmffat2016-05-30

Yeah small town usa. My neighbors wouldn't much care for the concept even if I could control the smell and it may even be illegal or aginst city code.

For rails 2 inch square tubing 3/16 wall thickness the length of your pad with small peices of angle iron welded to it to use as brackets to bolt it to the pad. Then use 10 inch steel wheels used for lawn equipment with the tires removed. Harbor freight sells on with duel bearings for 5 bucks a wheel. Three pairs would hold up 1000 pounds easy. Then build a frame out of 1.5 inch angle iron to set the IBC on. I would be all in cost of about 200 bucks in steel depending on how many rail cars you built. Totally unneeded but would be cool.

Tecwyn Twmffat (author)tjdux2016-05-31

Hmmmmnnn ....... Thinking about it ....... I might as well just buy a second hand pallet truck?

Tecwyn Twmffat (author)tjdux2016-05-30

Very cool !

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