Basically, NRC is just starting up in Dadaab, and one of the main identified needs, is for the building of 1500 latrines for a camp extension (as well as replacing/upgrading about a squillion other latrines in the older parts of the camp). (The general background: Dadaab was originally planned for 20 000 people, back in 1992, but now has about 160 000 people, with some extensions built since. It is in a semi-arid area, 100km from the Somalia border. Most of the population is Somali, but with minorities from Sudan, Uganda and Ethiopia).
The soil in one section of the camp complex is very sandy, whilst the soil in the other two sections is more clay-ey. From reports, it appears that the sandy soil is more of a problem, because the sides of the latrines there have a tendency to collapse.
I haven't been able to find any info about the water table. However, the camp sections would appear to have only 4 bore holes per 30 000-50 000 refugees, and can still supply the necessary 20l. p/d.
There is seasonal flooding caused by the rains, and at those times, there is a tendency for the latrines to overflow, spilling waste into the surface areas.
The latrines are in any case prone to overflowing, because there are no shower stalls in the camps, and the families use the latrines as shower stalls, so all of the grey water goes into the latrine pits.
In the older parts of the camps, apart from the most recent influxes, there is generally one latrine per family. But the latrines are very simple -- single pits protected by plastic sheeting and sticks. There don't even seem to be any adequate plinth slabs, or any reinforcements for the sides of the pit walls. When a pit is full, the families are encouraged to cover it with soil, and dig a new pit nearby.
None of the latrines have roofs, so the rains very easily fill the pits, and cause collapses of the pit walls. There are logistics difficulties involved -- the nearest point of supply is 100km away, by a road which becomes impassable during the rainy season.
Nevertheless, I am proposing to start with latrine building rather than the parallel shelter building programme, because (a) without latrines, it is less likely that the families will move into the camp extension, (b) latrines can be done with less materials/staff, (c) there are serious public health and waste management issues in the camp.
I'm assuming that I will have to propose at least two different types of latrine, or at least different pit dimensions, because of the different types of soil. Actually, it may be four different types, because I will also be required to oversee the building of group latrines for some new schoolrooms as well.
I'd like to look at latrine types which have perhaps double pits, or some other feature which would speed up the process of diminishing ... (more)
there are lots of questions there. Lots of answers in the inter-agency Excreta disposal in emergencies manual that Peter Harvey at WEDC is preparing. There's a draft on the Oxfam web page http://oxfam.org.uk/what_we_do/emergencies/how_we_work/manual_excreta.htm
In cases of having to deal with a lot of liquids, you could consider the latrine on p23 of the ecological sanitation: http://ecosanres.sei.se/pdf_files/Ecological_Sanitation_2004.pdf
The bottom is made of concrete bricks and in stead of digging holes, you provide the space in the structure above the ground. Main advantage: no collapsing latrines and a latrine that lasts. The structure above this structure can be made of 'soft materials' - e.g. wood + the tins from USAID. You wouldn't be able to use the tins at lower level as urine etc are quite corrosive. If there is somebody who does agriculture, they can dry the excreta and use as a fertiliser + in combination with an agri programme. Donors love this. The additional advantage is that you have less issues of flooding. The main disadvantage is off course costs and the concrete bricks you need (and the transport issue related to it). Another issue that you will have is drainage which will need to be sorted out. It seems odd, but I tended to have more problems with sandy soils for drainage in camps as they tend to clog drain pits etc. In one case, I gave up and had sort off a large, wide pit dug (not deep + fencing!!!! Beware of kids tumbling in!!!) and then pump the water out of it and spraying it outside the camp. You could have solar pumps working during the day and remove the equipment at night to minimise theft.
As for the Somali: as their community leaders + other NGO's. I have no experience with the Somali community apart from the one in London. If they don't co-operate: each their own latrine which tends to be better for maintenance issues. One thing you will need to keep in mind is that you may create jealousy between the old and the new population if you erect fancy latrines.
It sounds like a lot of toilets; you will need to go into mass production of slabs. I think Oxfam developed some moulds for this sort of problem but otherwise you could just cast them onto the ground.
I attach a scanned copy of the builder’s manual for the Zimbabwean Blair Latrine. The Blair Institute in Harare developed what was possibly the first VIP latrine and has since come up with several variations. I once had a British Labour MP who wanted to be photographed with one at the Harare Show to take back to his leader. In view of the current falling out between President Mugabe and Tony Blair there was a song going round here a couple of years ago “The only Blair I know is a Toilet!” This model uses 3 bags of cement for a brick lined pit, the slab and a brick superstructure. With a further bag of cement you can have a ferro-cement roof, but that can be made with other materials.
The sandy soil means that you will need some form of pit lining. If you cannot get concrete rings, perhaps bricks are possible. I imagine the food aid tins will be quite flimsy metal so that they would not be strong enough to use flattened out. Perhaps they could be filled with sand and used like bricks, or used as moulds to cast concrete bricks.
The other option if you cannot dig down is to build above ground with the cubicle perched on top of a concrete box that is the pit. This would need a lot of materials but is easier to empty if you are going for a double vaulted composting latrine. I don’t know if the use of composted latrine contents will be acceptable in this area. If they are not already used, you will have an uphill struggle to convince people to change.
The Vietnamese double vaulted composting latrine is widely used model in Asia and Latin America but I have not seen it anywhere in Africa. Such latrines are more complex in construction need more materials. They would also require more training for effective use and maintenance. Some construction details can be found at the following website but it is an M.Sc. thesis so may take a while to download; www.cee.mtu.edu/peacecorps/reports/Daniel_Hurtado_Final%20report.pdf. You would probably be better sticking to simple pit latrines in the area where you are working.
Latrines are much better managed when they belong to an individual family. Communal latrines tend to become filthy very quickly unless you want to start paying cleaners. In Zimbabwe we did build some latrine blocks for schools. These were simply lines of latrines side by side and, because they had brick superstructures, material could be saved by shared the intervening walls.
With regards to the flooding, I have had that problem in refugee camps in Azerbaijan and it is not pleasant. There the latrines were pumped out periodically ... (more)
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