CONSALLEN GROUP SALES LTD

HAND DUG WELLS   

 

Water at 15 metres in Togo

Modified Chicago Method of safe Well & Pit construction

The photo illustrates the use of a temporary support system for safe digging in open wells or other pits. Steel rings, wedges and timber boards ensure the safety of workers at any depth. In this case, support was only required for the first 4 metres. The 15 metre (50 ft) deep by 1.22 metre (4 ft.) diameter hole was the result of 4 weeks of volunteer labour in Togo.

Having found good water at 15 metres, a variety of well completion options are available. These include brick lining or precast concrete rings, in situ concrete, shaped blocks, clay tiles or a plastic borehole casing. Whichever method is used, the boards and rings are withdrawn as work progresses, for use in further wells, without waste or loss. The rings and boards are easily handled by one person. No lifting gear is required.

The following link is to a PDF file on hand dug wells using this technique. Hand Dug Wells (1.25 mb)

It may be noted that this technique is applicable to bulk sampling in prospecting for alluvial mining above the water table, and for other pits where hand labour is available.

 

CABLE PERCUSSION (Shell & Auger) DRILLING


A well at the site pictured above in Togo could have been drilled to depth in a single day by two men using the light cable percussion drilling machine shown right. It requires no water for the process, has only one small diesel engine, and will drill 20 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 a metre per day.

The single day's drilling would have demonstrated (1) that there was good water from 15 metres depth, (2) that there was at least enough to supply a hand pump, and (3) that the quality was good, (4) that there were no boulders. 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 would be confident that it would be successful in all respects, and would know the exact extent of work required. No other drilling method provides all this information before the hole has been fully cased and pumped out.

Full details of the drilling rig are under the following link: FORAGER-55/1250 DRILLING RIG

Consallen hand pump installed on the Togo well

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

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