Spring Well Design
Do you have a standard spring well design?
I intend to capture a spring that is coming out of the ground. I am also looking at a protected water collection point in a stream. Of course digging a well to 20m would give better quality water. However it is relatively more expensive compared to protecting a natural spring. Any information and recommendations that you can give will be very much appreciated.
Take a look at this excellent guidance note for protecting springs:
There is a publication 'Small Projects Training Manual, Volume II, Water Supply" authored by M and R Guoth-Gumberger which was published in1987 by the Sudan Council of Churches for the Mukini Water and Sanitation Project Sudan which has a section on spring protection if you can access it.
I probably cannot add much to the fact sheet Brian has sent you on spring protection except to say that springs are generally pretty clean sources if they are captured when they emerge from ground and animals and people are kept from polluting it.
I do, however, have a little information and a question that I would like to ask about Yei having spent a couple of months there with Oxfam in 1998.
Surface Water - as far as I can remember the river that runs through the town is perennial and before the war there was a pumping station with perhaps some treatment at the point where the main road crosses the river. When I was there the pump house was in some disrepair and was occupied by SPLA soldiers. A lot of equipment had been taken and we scavenged a few more bits of pipe for the work that we were doing to install an emergency water supply at the hospital. It may be possible (though quite expensive) to bring this back into action for the whole town.
Ground water - There are quite a lot of wells/boreholes around the town and 20m sounds about the depth the pumps were set at though the static water level was much closer to the surface in the borehole that I rehabilitated (about 7m I think). Some had been filled in with stones by one or other sides during the fighting but others were still operational with hand pumps.
I would be really interested to know if my system is still operational though I would not be surprised if it is not as at the time the hospital was subject to frequent bombing from the north and I think mine was the third system that had been built there. We put a submersible pump powered by a generator in a borehole the other side of the road from the hospital. It pumped to a water tower which fed 6 Oxfam tap stands distributed around the hospital.
Just to make two points:
A surface spring does not mean that a hand-dug well will be successful at that location (or even slightly up-stream). Springs can occur in geological conditions unfavourable to hand-dug wells.
Even if the formation were favourable, you might find it very difficult to dig a 20m well there, even with caissoned well rings and mechanical dewatering.
One issue is whether the spring is used just for people or also for watering animals. This should be allowed for in the design, or the needs of the animals will take precedence.
This thread is public, all members of KnowledgePoint can read this page.