Request for advice on UDDT slab design - and drying in vaults that are below ground?

  • Angus
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Request for advice on UDDT slab design - and drying in vaults that are below ground?

Hello,

I'm working on a project in Gambella, Ethiopia, to install UDDT and Tiger Worm toilets into a refugee camp as a more sustainable solution than building and rebuilding pit latrines.

I'm looking for advice regarding the slab. At the moment I'm using a design used successfully elsewhere in Ethiopia. I've attached a drawing of it to this post.
It gives a nice end result but is a little complicated to make, with a urine pot having to be cast separately. We need to make a lot of toilets quickly so any improvements to the design which can aid this, whilst still giving a good finish, are welcome.

Does anybody on this forum have any good ideas for any improvements on this design?

Thank you!

Angus

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  • JKMakowka
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Re: Request for advice on UDDT slab design

I have seen people just embedding large plastic funnels into the slab to avoid the issue of two different molds and joining them. It also makes it easier to clean urine stains and attach a flexible hose to the outlet.
But it might be difficult to procure sufficiently sized ones. Maybe one could improvise something out of a plain galvanised iron sheet?

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  • daymaker
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Re: Request for advice on UDDT slab design

Hi,

If you did want to form the urine pot from galvanized sheet steel, I can convert this shape into a flat pattern for you, with fold lines and instructions. I think it wouldn't last forever, as the urine would eat away the steel, but I think it would last at least a couple of years?

Let me know,
Lauren
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  • Angus
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Re: Request for advice on UDDT slab design

Thanks Krischan for the advice, and thanks Lauren for the offer of making the template. I don’t want to save on construction cost and complexity if it is going to end up reducing the lifespan of the UDDT though!

I think we will have to stick to using cement for now!

Angus
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  • Angus
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Re: Request for advice on UDDT slab design

On a different but related note, we are currently building the toilets with the lowest course of bricks for the vault below ground level. This is so that people do not feel self-conscious climbing up to the toilet.

It has been suggested this might reduce the effectiveness of the drying inside the vault. Does anybody have any experience of vaults that are sunk below ground - did it make any difference to the drying?

Thanks again,

Angus
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  • JKMakowka
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Re: Request for advice on UDDT slab design

That would probably depend on the local temperature day/night variations. If in your work area it cools down significantly during the night, a partially below ground vault will probably retain some of the coldness during morning hours and cause dew to form.

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  • Angus
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Re: Request for advice on UDDT slab design - and drying in vaults that are below ground?

I'm in Gambella, Ethiopia. The temperature variation isn't too large, see here:
http://www.worldweatheronline.com/gambela-weather-averages//et.aspx

Therefore, I think they will be ok slightly buried.

Thanks for the advice - I would never have thought of that myself.

Angus
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  • muench
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Re: Request for advice on UDDT slab design - and drying in vaults that are below ground?

Hi Angus,

I really like your plan to build UDDTs without stairs. So many times I've seen UDDTs with steep and narrow stairs and wondered "is this really a good idea? How about the elderly and people with disabilities?!".
My gut feeling is that having the vaults below ground wouldn't be that detrimental to drying. Wouldn't most of the drying be influenced rather by the correct vent pipe arrangement and - more importantly - by users taking care of not letting urine enter the faeces vault? (provided you can ensure that no rainwater or flood water enters your vaults)

Also, I remember the UDDTs built in the Durban area used the slope of the ground to do away with stairs but still have the vaults mostly above ground. The user enters the toilet at the higher part of the slope and the access doors is at the lower part of the sloping ground. That's if the area is sloping a bit (see case study from 2011 here: www.susana.org/en/resources/case-studies/details/791 and more documents in SuSanA library can be found by using the search term eThekwini).

Would be great if someone from EnviroSystems in South Africa could also comment. I will alert Jacques to this thread.

Please do let us know how you get on with those UDDTs in Ethiopia.

Cheers,
Elisabeth

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  • canaday
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Re: Request for advice on UDDT slab design - and drying in vaults that are below ground?

Dear Angus,

I agree with Elisabeth that it is great to avoid or minimize the steps. Plus you are working in Ethiopia, not here in the Amazon, so the water table is likely very deep in the ground and flooding is not likely to happen.

I am sorry to say that I have trouble understanding your plan for the squat slab, but I would nonetheless like to offer the following comments:
-- Round drop holes for feces would be easier to keep clean. These could even be formed with short sections of PVC pipe and thus be even easier to keep clean.
-- If the urine basin is to be molded individually in concrete, it would be hard to clean and it would absorb some percentage of urine and thus produce odors. The plastic funnel that JKM mentions might be a great option.
-- This seems to be a 2-chambered UDDT, so how do the Tiger Worms fit in?
-- Since this is for a refugee camp, it seems the toilets would receive a lot of use and each chamber may likely fill before 6 months has passed and proper treatment would not have time to occur, unless the chambers are very large. In any case, the amount of use would likely be unpredictable, thus a 1-chambered UDDT with interchangeable containers may be preferable. These containers could be woven, polypropylene sacks in which rice, flour and other foods come to the camp; they can be held open on plastic bins or woven baskets. Filled sacks could be stored in a shed that works as a solar oven, or they could be buried in the ground for over a year.

Have you ruled out the ArborLoo? I think that would be a great option for there, since no one has to worry about urine separation and no one ever comes in contact with fresh feces or even decomposed feces, just the delicious fruits on the trees. I can imagine teams of refugee men building them and teams of teenagers digging the holes, relocating them and planting trees. If cement floors are done, these could be round and rolled from site to site. The privacy structure could be separate and lightweight.

Some of these ideas can be seen on inodoroseco.blogspot.com

Please keep us informed.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
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  • bitwire2010
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Re: Request for advice on UDDT slab design - and drying in vaults that are below ground?

Dear Angus

Hope your project is moving on smoothly. This is Arnold here in Uganda. I would propose that you use plastic pans. They are easy to install, easy to clean and drains away the urine. Here in Uganda it costs around USD 15.

For the stairs I think they can be avoided if one locates the UDDT on the slopping side. You can also use ramp instead of stairs to cater for the elderly and the disabled.

Attached a few photos I can share with you.






Arnold Asiimwe
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  • Angus
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Re: Request for advice on UDDT slab design - and drying in vaults that are below ground?

Thanks all for the advice, it's very useful!

Controversially, we aren't putting a vent pipe on the first round of UDDTs. This is because normally for any type of latrine the vent pipe is the first thing to go wrong, and I think that in this hot climate the faeces will be able to dry through the drop holes and through gaps in the structure. If it seems to be an issue we will retrofit them.

We haven't been able to eliminate the steps, only reduce them. Putting the toilets uphill is a nice idea, but most of the area we are working in isn't steep enough to mean there are no steps required. We are going house to house looking for people with disabilities, so if anybody can't use the steps then I will think of a specific solution for them.

Regarding the 'user interface', I would love to use a nice plastic insert but there are none available locally and it's not possible to import anything. I can't see why would round drop holes be easier to clean? I will have a hunt in the market again for anything that would be suitable for catching the urine.

The UDDTs are one per household, so I'm expecting the filling rate to be normal. The tiger worms are unrelated - we building worm toilets separately, and will see which works best. The Arboloo is great, and is similar to what is happening here - sturdy concrete slabs that are moved when the latrine is full. The reason for using the UDDTs and worm toilets though is that they are more suitable when the ground conditions aren't good. A lot of UDDTs were build in Dollo Ado, Ethiopia, where the ground was rocky, and here in Gambella there is black cotton soil which means that normal latrines are at risk of collapsing.

Angus
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  • kifle1adama
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Re: Request for advice on UDDT slab design - and drying in vaults that are below ground?

Dear Angus

Hope your project is going good . I have same moled you can use fiber glass . They are easy to install, easy to casting and drains away the urine. Here in Adama Ethiopia +251911797053
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