HAND DUG WELLS

( pick & shovel technology for large diameter holes )

Modified Chicago Method of safe well construction

The photo illustrates the use of a temporary support system for safe digging in open holes. Steel rings, wedges and timber boards ensure the safety of workers at any depth.

Having found good water at 15 metres, a variety of well completion options are possible. These include brick lining or precast concrete rings, in situ concrete, shaped blocks, clay tiles or a borehole casing. Whichever method is used, the boards and 1.22 m rings are withdrawn as work progresses, to be used again in further wells, without waste or loss.

It took 4 weeks to arrive at the stage shown here in Togo, by hand labour in hard stoney ground just out of the flood plain. This would have been the work of a single day using the cable-tool drilling rig shown below.

CABLE TOOL (CABLE PERCUSSION) DRILLING

A well at the site pictured above in Togo could have been drilled to depth and completed in a single day using the light cable percussion drilling machine shown right. It will drill 30 metres per day in any material in which it would be practical to hand dig. The best that can be expected of hand digging using pick-and-shovel methods is 1 metre per day, with a team of 8 to 10 men.

The single day's drilling would have shown that there was good water from 15 metres depth, that there was at least enough yield to supply a hand pump, and the quality was good. A decision could then have been made to either case the hole as a borehole, or commence hand digging an open well, confident that it would be successful in all respects, and knowing the exact extent of work required. No drilling method other than cable percussion provides all this information before the hole has been fully cased and pumped out.

Full details of Cable Percussion drilling can be found at: http://www.consallen.com/forager/cable-tool/

HAND PUMP

The hand dug well in togo shown above was fitted with a Consallen hand pump.

The well was completed using a plastic borehole casing, and back-filled before the concrete slab was laid and the pump stand mounted. By selecting clean sand & gravel from the excavated material a good 'gravel pack' can be made in the water-bearing zone. This provides a good wide area for water flow to the screen section of the casing in addition to some storage volume. In this instance, storage was not a major requirement for this high yielding well. Bailing with a 100 litre bucket at 2000 litres per hour did not measurably depress the water level.

Details of the pump can be found at this link: http://www.consallen.com/handpumps/

Details of the Modified Chicago Method of hand digging can be found at: http://www.consallen.com/Hand_Dug_Wells.pdf

Home: http://www.consallen.com

Consallen Group Sales Ltd., P.O. Box 2993, Sudbury, Suffolk CO10 0ZB, United Kingdom.
Tel: +44-(0)1787-247770; e-mail: sales@consallen.com