Dear Carlos,

How are things going on this topic?

Soak pits are basically to make the urine disappear, but it is better to achieve productive recycling of the nutrients. If there is enough space, I like to disperse the urine in perforated hoses buried 10 cm below the surface of the soil, among plants, with roughly 2 mm holes every 50 cm. The hose for the toilet of a family may be 12 m long.

Best wishes,
Chris

Dear Elizabeth,

Thank you so much for your help, I appreciate it so much, I will review all the information at this moment.
At this moment, in ECOSAN foundation we are making some studies for evaluate the best options for the managment of source-separated urine in several contexts in Chile (differents climates zones, types of users, etc.). One of this alternatives of management in decentralized-sanitation is the infiltration of the urine through the soil using a soak pit, we need some background for adequate our design to what happens in the reality, for this reason, I am searching some case studies that allow me to know another experiences about this topic.

Thank you very much again

Best Regards

Carlos

Dear Carlos,
Nice to hear from you again. Please tell us more about your UDDT project in Chile?

For urine infiltration in the soil we have Chris Canaday (Ecuador) as an expert who uses it not just to get rid of the urine but to use it for fertiliser, too.* I guess that is your first question: do you have space (and water) to grow plants with the urine or do you just want it to disappear (and is the groundwater level deep enough and protected enough to not cause any harm there, i.e. groundwater pollution)? Urine soakaways without trying to grow plants are used in the large UDDT projects in Durban and Lima.

In the Wikipedia article on UDDTs, we have written it like this:
en.wikipedia.org/wiki/Urine-diverting_dry_toilet#Urine

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In cases where no reuse is possible or desired, urine is usually infiltrated in the soil unless this practice would cause groundwater pollution. In eThekwini municipality in South Africa[24] or in Lima, Peru, for example, urine from UDDTs is safely infiltrated into the soil because the groundwater level is very low there and the groundwater is not used for any particular purpose. Infiltration can be done by directing the urine to a soak pit or by running a perforated urine pipe from the toilet to an area outside, where the hose is sloping gently downhill (for rural areas). Clogging of the pipe's holes can be avoided by ensuring there are no T-junctions, no joints and that a plastic mesh is installed in the urine funnel of the toilet to keep everything other than urine out.
++++++++

And the GIZ Technology Review of UDDTs also mentions it briefly on page 33:
www.susana.org/en/resources/library/details/874

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A soak pit – also called a soak away or leach pit – can be
covered or uncovered, and either empty or backfilled with
coarse material. Depths can range from about 1.5-4 m,
depending on the anticipated volume of urine and the
hydraulic conductivity of the soil. The pit may be lined with
a porous wall to provide structural support. Technical
details for construction can be found in Tilley et al. (2008).

A concrete ring beam with a lid should be placed at the top
of the soak pit to raise it slightly aboveground level and
thus clearly demarcate its location. Foreign materials often
fall into or are placed in uncovered pits, increasing the
likelihood of clogging. Therefore a cover is of advantage.
Alternatively, an infiltration trench offers another infiltration
option. Such a trench is composed of an approximately 5
cm diameter punched pipe, or diffuser, that is attached at
the discharge point of the urine drainage system. The
diffuser is placed in an approximately 0.5-1 m deep gravel
lined trench (see Figure 43) and the urine is discharged
into the subsurface over the length of the diffuser.
Vegetation can be planted alongside the trench to make
use of the urine nutrients.

Under certain circumstances urine may be drawn back
towards the surface by evaporation and capillarity, leading
to salinity issues but also increasing the likelihood that the
nutrients in urine will be taken up by plants which may be
planted next to the infiltration trench. The fate of the
infiltrated urine depends on the quantity, infiltration basin
size, as well as soil and climatic conditions.
Urine can infiltrate deep into the soil, potentially reaching
groundwater resources. Therefore it is important to conduct
an assessment of groundwater pollution (see following
Section) prior to the implementation of urine infiltration in
order to prevent unexpected environmental pollution.

Villa Maria de Triunfo/ kindergarten: separated infiltration by SuSanA Secretariat , on Flickr

Foto caption: Figure 43. Left: Construction of a subsurface infiltration
trench with gravel for greywater and urine at a school in
Peru (photo: H. Hoffmann, 2009).

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Please ask if you'd like to know more details?

There is also this sub-category on the forum where you might find more clues:
forum.susana.org/forum/categories/175-fo...euse-or-infiltration

We actually struggled to get good photos of urine infiltration soakpits or pipes for the GIZ technology review. So if anyone has additional ones to share please upload them to the SuSanA flickr database (please send them to This email address is being protected from spambots. You need JavaScript enabled to view it.)

Regards,
Elisabeth


*
More information about the UDDTs and urine infiltration in Ecuador by Chris Canaday is here on the forum:
forum.susana.org/forum/categories/34-uri...iew-on-uddts-ecuador

and
forum.susana.org/forum/categories/34-uri...ourself-uddt-ecuador

He also has lots of materials about UDDTs in Spanish.

hey to all from Chile

I need to know information about the use of soak pits for infiltrate the source-separated urine in the soil. If one of you can help me with this it would be helpful to our investigation about UDDT in Chile

Thanks to all!

Best Regards