Low Cost Well Drilling
Low Cost Well Drilling -
Well, I just contradicted myself, digging is not drilling. But the traditional African well-digger is still the lowest-cost option for getting water. It seems like hard work at first:
But as the hole gets deeper, it turns into a really difficult and dangerous task:
There are dozens of these wells in the District of Koka, where our current project is, and the well diggers deserve a lot of credit for the work they’ve done over the years.
Throughout Africa, hand-dug wells are the mainstay of Self Supply – families who pay for their own water source, usually conveniently located near their home. Self supply is widely practiced in the US, providing water for over 43 million people nationwide, mostly from drilled wells. (see https://www.usgs.gov/special-topic/water-science-school/science/contamination-us-private-wells?qt-science_center_objects=0#qt-science_center_objects)
The main drawback to hand-dug wells is contamination. Hand-dug wells can be seen in every village – low, round structures made of stone or concrete, with a bucket tied to the top of the structure by a rope, and chickens or goats wandering nearby, ready to lap up any water that the users might spill. Whenever the buckets are set on the ground, they pick up bacteria and transfer them to the inside of the well. Older wells usually have a gray or green coating near the water table that has to be cleaned off periodically by someone going down in the well with a scrub brush.
There have been many projects over the years in several African countries to try to extract the water from hand-dug wells without contamination. This usually involves digging a new well, installing a hand pump, and covering the top of the well.
The Rural Water Supply Network has some excellent resources on self supply:
A self-supply project case study using hand-dug wells in Zimbabwe is described at this site:
Malawi’s Smart Centres provide online resources for several techologies, including hand-dug wells:
Low Cost Well Drilling -
The SHIPO Method and Hand Auger Drilling
The second cheapest method of well drilling is hand auger drilling. The augers make a narrow borehole rather than a wide well, so the well is completed with a casing pipe, filter pack and pump rather than a bucket and rope. They work well in sandy soil and soft clay – mostly near the coast or in a wide river valley. When the borehole reaches the water table, the wet sand can easily slump into the hole, and drilling can’t advance any further.
To drill a well deeper than the well diggers can go, you must use a fairly heavy auger that can push aside pieces of gravel and cut through clay. When the auger fills with cuttings, it has to be pulled from the well and emptied. You can imagine that this step gets to be time-consuming when the well is deeper.
The SHIPO method addresses both problems – the removal of cuttings and the limited applicability – by adding just a few more simple tools. The method is illustrated at the Smart Centre web page http://smartcentregroup.com/index.php/technologies/manual-drilling-shipo-drill/
and a manual is available upon request.
This method replaces the auger rods with pipes, and uses water to lift the cuttings out of the borehole through the pipes, without removing the auger from the hole. Water must be carried to the site and the borehole is kept full of water throughout the drilling process to avoid slumping of saturated sand, and to carry the cuttings up through the drill pipe. The drilling process is continuous and the borehole can be drilled well below the water table. The deeper boreholes usually require that a tripod be constructed over the hole to help pull the drill string from the hole, and a pump can be added to remove the cuttings even faster.