Water fro Humanity - Appropriate Technology

HAND-AUGERED WATER WELLS

by Steve Herbert

In developing countries, the hiring of a truck-mounted drilling rig to drill a bore hole is very often cost prohibitive for the average family, or even community. Even use of the portable drilling equipment such as the DeepRock HydraDrill which Water for Humanity has used in Honduras, El Salvador and Haiti can present its financial challenges. However, sometimes where the groundwater is shallow enough and where the ground is sufficiently soft, simple manual technologies are a possibility. Hand-augering is one such technique.

An auger is basically a cylinder with teeth on the lower end when positioned vertically, and is attached to a “T” handle on the upper end to manually turn the whole assembly. As the assembly is positioned on the ground and turned, the teeth cut into the earth and draw the auger deeper by its own weight and pressure applied by the operators. Alternatively, an auger bit may consist of a stem with a spiraling blade such that typical of post-hole diggers. This version screws itself into the earth as it is turned. All augers require that the assembly be retracted every few inches to clear the hole of cuttings.

There are two basic versions to the toothed version. The simplest design requires that the auger be retracted, and then a bailing mechanism be dropped down to capture the loosened earth and extract it from the well bore. This may be constructed of a thicker-walled pipe with an improvised “check valve” fitted to the lower end. The weight of the cylinder provides an advantage in capturing more of the sediment when it is dropped. It is then pulled out with an attached rope and dumped. Admittedly, this is labor intensive, but far more affordable a method compared to powered equipment.

The second version by design enables the operators, which are typically two, to drill and capture the cuttings in one step. In these, rather than having two large opposing “teeth”, there will be more and smaller teeth, set closer together. This and the fact that the loosened material naturally becomes compacted within the cylinder, allows the auger to be retracted with material retained in the cylinder, even without a check valve. The cylinder must then be knocked to cause the cuttings to fall out.

One advantage of hand-augering a well is that you always know precisely when you have hit water. The material extracted from the well may be relatively dry until quite suddenly is becomes very obviously more wet. Since one is looking for water that is relatively shallow, there are some common-sense ways to decide where to drill. Being observant of the vegetation is one such obvious method. Where it is clearly more green and lush, there is likely moisture closer to the surface. Another clue can come from the topography, which can dictate underground drainage patterns. Of course, if you’re a dowser, you have an additional method. One should be cautioned, however, not to position shallow wells too close to latrines or other potential sources of contamination, especially if they are upslope.

In researching this article, I ran across a particularly good website on the subject, at www.hydromissions.com. This is posted by a missionary organization, which admits their first objective is to spread the gospel and only secondarily toward aid and development. Not surprisingly, they are not “dowser-friendly”, but they do specialize in a number of very good appropriate technologies, including hand augers. Hydromissions International, LLC, based in South Carolina offer a hand auger kit, which is so portable it can even be checked as a bag onto an airline under the international baggage weight limit. Their Explorer drill system is capable of hand-augering as deep as 100 feet. The depth limitation, given softer soils, is mainly due to the weight of cuttings plus combined weight of auger and accumulated attached stems. The EXP-50 kit has enough three-foot stems to give it the capability of drilling up to 50 feet. More stem can be purchased separately. No auger can go through solid rock, but an optional “cracking bit” can be used in more difficult soils, or a percussion kit may do the job.

The Hydromissions website explains that a reasonable expectation of drilling rate is approximately ten feet per hour up to twenty feet, then dropping gradually down to five feet per hour thereafter. Therefore, a fifty foot well would take about two days. A Hydromissions employee explained to me on the phone that their five-inch self-burrowing auger with beveled teeth makes a 5 1/2 “ to 6” hole which comfortably fits a 4” casing. Their regular bit has 1 ½” separated teeth, she told me, but a special sand bit has even closer teeth and there is a mud auger for clay as well.

Both Richard Roy and I have been introduced to this technology in Haiti. I myself have seen that conditions in the north of Haiti around Cap Haitien, for example, are suitable for this. It has much potential worldwide where groundwater levels and soil allow. Beyond this, I have been impressed with the improvisational spirit of people like the Haitians where funds are sorely lacking.