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RedR TSS

Further to Tim Foster's message I would agree that Engineering in Emergencies (page 252 - 253) has some good information on this subject. It is also worth looking at Section 13.3.3 on disinfection. If Richard does not have this book with him in the field I could scan and send these pages but apparently I am not allowed to do this without the written permission of the publishers. Perhaps Toby could help with this if necessary.

Instead I attach a couple of pages from "Hand Dug Wells and their Construction" by S.B.Watt and W.E. Wood. This is also an IT Publications but in 1979 they did not put in the clause forbidding any reproduction.

While pumping out and disinfection will be needed after a flood. The effects of the disinfection will not last more than a few days. All open wells are prone to contamination and they should be protected with headworks that could include a cover slab or a raised wall to prevent water from running in. The surrounding area should be fenced and any potential contaminating activities such as clothes or personal washing or livestock watering should be removed from the immediate vicinity of the well.

One common source of contamination is people using their own buckets to draw water. These buckets are put down anywhere and pick up contamination. It is better to use a single bucket in the well which is tethered to stop it from being taken elsewhere. Better still is to use a hand pump, but only if the support facilities exist in the form of trained technicians and a supply chain for spare parts.

The costs of a simple disinfection would be low, chlorine should be available in some form in Accra and bleach would be available in most small towns/large villages in Ghana. If your project also wants to build headworks you will also need cement, reinforcing bars and aggregate, all of which should be available locally.

One important safety issue is that the exhaust fumes from any motorised dewatering pump must not be allowed to enter the well if people are working underground. There have been cases of people being asphyxiated and the same fate befalling people who try to rescue the first victims.

Martin