Rural Gravity Water Supply in Nepal
We are assisting a small charity putting in a new rural gravity water supply in Nepal. A design has been done by an local engineer from the DWO which includes approx. 2km of buried pipe (50mm and 32mm dia)-he has been to site and seen the terrain. The funders are concerned over the labour cost and feasibility of burying the pipe which contours round a steep forested hillside and want to lay it on the ground instead. I think we will be using HPDE pipe and suspect using a DI pipe above ground would be more expensive than the labour costs of burying an HDPE one. I'm also concerned about damage to an above ground pipe, either intentional or by animals, people cutting foliage for animals etc. Any advice on the way forward appreciated, including some estimates of m/day of trench that can be achieved by hand in difficult terrain, I assume depth of burial should be to 1m. What is reasonable to ask the community to contribute in terms of free labour as their contribution to the project?- I've seen figures of around 20% of the capital cost?
Lisa Varey Principal Engineer
01946 598927 www.westlakes.co.uk
Posted by LC Jones, RedR KP Moderator
I would agree that laying on the surface is a poor option for all the reasons you mention. Also anything which moves cost from investment to maintenance mustbe thought through carefully as maintenance is always the challenge. Jordan's book https://www.developmentbookshelf.com/d... gives estimates of how many m/day. Re community contribution, I am unsure but suggest talking to other organisations working in Nepal to see the range then discussing with people involved. Good luck
We are building very similar DWSS right now here in Nepal (Gorkha district). Trenching of HDPE pipes is highly recommended, but due to climate and habits no need to bury it 1m deep (which would be indeed an issue I guess). Estimates for how long it takes to dig are hard to do, as community labour availability is highly seasonal. So sometimes it takes several weeks and sometimes it is done in a few days...
The usual pipe trenches are maybe 30-40cm deep, which are later simply backfilled with the earth taken out. In most of the hilly region freezing of pipes (the main reason why you would want to dig deeper) is not really an issue, and higher up communities are very used to keep water flowing during cold spells to avoid pipes freezing shut and bursting.
We usually ask the community to contribute the digging and they seem to have no problem with that. In our internal calculations the community contributions for free labour are usually around 20-30%.
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