Hand auger - general
The hand auger is suitable for unconsolidated formations: sand, silt and soft clay. Stiff clays, hard materials and gravels are difficult or impossible to drill through and to remove (unless augering is combined with percussion).
The hand auger consists of extendable steel rods, rotated by a handle. A number of different steel augers (drill bits) can be attached at the bottom end of the drill rods. The augers are rotated into the ground until they are filled, and then lifted out of the borehole to be emptied. A different auger can be used for each formation (soil) type. Hand augering can be done both by using a heavy tripod and winch (such as the Vonder rig), or with lighter materials.
Above the water table, the borehole generally stays open without the need for support. Below the water table a temporary PVC casing may be used to prevent the hole from collapsing, and can be emptied either with an auger or a bailer. The permanent well casing is then installed, while the temporary casing is removed.
Another option is to use the well casing used as support for the borehole as the permanent casing (direct installation), although in that case a gravel pack can not be used.
Augers can be used up to a depth of about 15-25 meters, depending on the geology.
|- Easy to use above the groundwater table|| - It may be very difficult to remove the temporary casing. If clay layers are penetrated, it is very difficult to use a temporary casing, as it sticks to the clay.|
- The borehole does not stay open if a collapsing sand layer is encountered below a clay layer (through which the temporary casing could not penetrate).
Construction, operations and maintenance
It takes quite some expertise to drill a completely straight borehole.
All tools can be made in local workshops (with local materials) and are commercially produced in western countries (but more expensive).
- The tools for Hand augering can be made in local workshops.
- Chafagane Maiga (S/C BP: 10988 Niamey, Niger, Tel: +227 96 53 18 88) - Light and effective hand auger equipment.
- Eijkelkamp Agrisearch Equipment - Drilling equipment and manuals on hand auger and percussion gouges.
- Van Reekum Materials - Drilling equipment, hand auger and percussion drilling.
The hand auger is widely used in Niger, Chad, Senegal, The Gambia, Uganda, Zimbabwe, Tanzania, Nigeria, Central America and western countries.
- Julien Labas and Robert Vuik, Augering: Manual Drilling Series. TECHNICAL TRAINING HANDBOOK ON AFFORDABLE MANUAL WELL DRILLING. Practica Foundation. June 2010. French version: LA TARIERE MANUELLE: Série forage manuel.
- Jonathan Naugle, Hand Augered Garden Wells. Lutheran World Relief, third edition 1996. This is a manual on hand augering, well construction, and manufacturing tools.
- Drilling & well construction reference manual. Lifewater Canada, update 2004. This is a manual on hydrogeology, well construction, all drilling techniques, hand pumps and more. Other information can be found on the website of Livewater.
- Koegel, R. (1985), Self Help Wells, FAO Irrigation and Drainage Paper. FAO, Rome.
- Carter, R. C. (2005) Human-Powered Drilling Technologies. An overview of human-powered drilling technologies for shallow, small diameter well construction and domestic or agricultural water supply]. Silsoe College, Cranfield University, Bedfordshire, UK.
- Private Sector Participation in Low Cost Water Well Drilling. Cranfield University, 2001. Article on private sector participation in low cost water well drilling in Africa.
- Rural Water Supply Network - Useful network and website for information and downloads related to Rural Water Technologies - Hand drilled wells. General website.
- Peter Wurzel, Drilling Boreholes for Hand pumps. Skat, Switzerland, 2001. A book on hydrogeology, well construction, drilling techniques, well development. Website of SKAT
- M. Sonau, Low-cost shallow tube well construction in West Africa. FAO - An overview of shallow tube well drilling techniques. Website of FAO documents.
- Bob Elson and Rod Shaw, Technical note 43. Simple drilling methods. WEDC. An overview of simple drilling methods. Website of Loughborough University Technical Briefs section. Website of Loughborough University WELLS.
- A Water Handbook, Technical Guidelines Series. UNICEF, 1999. Programming and implementation.
- Technology notes, section 7: Tube wells and boreholes. WaterAid. An overview of human-powered drilling technologies. Website of Wateraid.org.
- Water for the World, Technical note series rws 2, USAID 1982 - Technical notes on methods of developing of groundwater, manual drilling techniques. Website Livewater International.
- Multi-service procedures for well-drilling operations. US Military. Alternative well construction and manual drilling techniques.