|
HAND DUG WELLS
|
|
A better Method of safe Dug Well Construction The photo shows a temporary support system for safe digging in open wells. Steel rings, wedges and timber boards ensure the safety of diggers. In this 15-metre well, support was only required for the first 4 metres. Nothing requires the use of lifting equipment as all the components of the system are easily man-handled, and can all be locally made - drawings are available on request. Having found good water at 15 metres, a variety of well completion options are available: brick lining, precast concrete rings, in situ concrete, shaped blocks, clay tiles or a plastic borehole casing. The boards, wedges and rings are withdrawn progressively as work procedes, for use in further wells, without waste or loss and without the use of any lifting equipment. This system has the advantage that if the well is unsuccessful - for any reason - no materials or equipment is lost upon abandonment; the protection system is withdrawn in the reverse of the installation procedure in complete safety. If a boulder frustrates digging using caissons, all the sections installed to that point are lost - at considerable expense. This particular well was completed using a 4-inch plastic borehole casing and back-filled with excavated material. Gravel and sandy materials were selected for the lower back-fill, and clay was selected for the upper layers to seal the hole against surface water pollution. It was finished with a concrete slab containing steel reinforcement to prevent cracking. Details of the Boarded Method of hand dug well construction
|
Successful well hand dug in Togo for a church/village development and fitted with a Consallen hand pump. Click for details |
|
LIGHT CABLE PERCUSSION DRILLING
The 15 metre (50 ft.) hand dug well pictured above in Togo was the result of 10 men working for a
month. A borehole in the same place could have been drilled in one day by two men
using the light cable percussion drilling machine shown right. It requires no water
for the process, and has one small diesel engine that uses about 3 litres of fuel per day.
A driiled hole would have demonstrated (1) that there was good water from 15 metres, (2) that there was at least enough to supply a hand pump, (3) that the quality was good, and (4) that there were no boulders that might prevent hand digging a well in the same place. A decision could then have been made to either case the hole as a borehole, for use with a hand pump, or to hand dig an open well for use with buckets. Whichever option was chosen the project could be confident that it would be entirely successful. The knowledge gained from a low cost survey/pilot hole would have enabled an NGO to obtain fixed prices from local contractors for completing an open hand dug well if hand pumps were not to be employed. A feature of the drilling system is that it can complete drilled wells at a diameter suited to the use of a bucket bailer to abstract water without using a mechanical pump. Details of the rig can be seen under the following link: CONSALLEN FORAGER RANGE DRILLING RIGS |
 |
Consallen Group Sales Ltd., P.O. Box 2993, Sudbury, Suffolk CO10
0ZB, UK.
Tel: +44-(0)1787-247770; e-mail: sales@consallen.com