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[[Image:Rota_sludge_well_drilling_iconTreadle_pump_icon.png|right]]EMAS [[Image:Emas0.jpg|thumb|right|150px|Emas well drilling is a method for drilling small-diameter tube wells by hand, up to 100 m deep. The drilling method is a hybrid between washboring, percussion and rotary drilling. It permits to drill through all kinds of loose soils, as well as consolidated materials and light rock. It will not, however, penetrate hard original rock or boulders (e.g. ancient river beds underground). The usual diameter of the tube well is 37 mm. __NOTOC__]]
[[Image:Emas.jpg|thumb|right|150px|Drilling a well in Colombia with the EMAS method.]]
[[Image:Emas1.png|thumb|right|150px|All the equipment needed easily fits on a small hand-cart.]]
[[Image:Emas7.png|thumb|right|150px|Wetting the cement for the pump base.]]
__NOTOC__
The EMAS method of manual drilling is a hybrid between [[Jetting - general|Jetting]], [[Percussion - general|percussion]], and [[Sludging - Rota Sludge|rotary]] drilling. A manually powered mud pump is used, and the drill stem is turned through 90 degrees at the end of each stroke. It permits to drill through all kinds of loose soils, as well as consolidated materials and light rock. It will not, however, penetrate hard original rock or boulders (e.g. ancient river beds underground). The usual diameter of the tube well is 37 mm.
==History and social context==
The EMAS drilling method was developed by the Escuela Móvil de Agua y Saneamiento (Mobile School for Water and Sanitation, EMAS) in Bolivia. Project leader of EMAS in Bolivia is Wolfgang Eligius Buchner, born 1957 in Holzkirchen bei München.
EMAS was established in 1993, and has provided training for about 130 independent well builders in its branches in San Julian (1994) and in Puerto Pérez (1997). 20 students have been able to graduate from the licensed craftsman course. The well builders in Bolivia have founded a well builder organization.
During a three-month education, agricultural workers are trained to independently drill wells, build sanitary installations and market their skills in their local area depending on demand.
The need for large financial investments for well drilling and the building of line systems has traditionally prohibited the construction of large scale potable water systems in rural areas. Wolfgang Buchner adapted already accepted suction - and rinsing drilling methods to local conditions.
EMAS is not only the name of the mobile school for water and sanitation, but also a whole technical and social concept of water and sanitation which includes rain water harvesting, solar water heaters, windpower, hydraulic rams, water treatment, small tanks and sinks, a variety of hand and foot pumps, and ferrocement tanks.
==Suitable conditions ==
Wells as deep as 90 meters can be drilled within 3-4 days without any machine employment and exclusively through the use of manual labor. Depths up to 100 m have been reached with the EMAS method. Most regions of South America (loam and sandy soils) are geologically suitable for this drilling method (predominantly rinsing or suction drilling). This technique is suitable for weakly cohesive sands and silts. It adapts best to loamy soils, consolidated materials and light rock. In sticky clays, the mud injection orifices in the bit can get blocked. In pure coarse sands, progress may be slow: the space between the drill stem and the well walls is relatively large, in relation to the slender drill stem, which makes for a slow upward flow. Sand may sink faster than it can be lifted out with the drilling fluid. In such conditions, it may be beneficial to (temporarily) switch to a sludging technique. {{procontable | pro=- Very quick in fine and medium sand formations.<br>
- Very simple and cheap equipment. <br>
- No need for machines. <br>
- No need for motor-powered mud pump and tower.<br>
- Can work below the groundwater table. <br>
- Uses non-corrosive, easily accessible and processable materials (PE and PVC). <br>
- Low maintenance costs <br>
- Low cost (approx. US-$ 6 per meter of depth inclusive including hand pump) allows for a surface covering potable water supply in the rural area. This is approx. about 10 times more economical than the least expensive commercially available method. <br>
- Adaptable to other countries and regions with similar soil conditions.<br>
| con=- Does not penetrate rockGenerally limited to sandy soils. Soft clay will be penetrated only very slowly and coarse gravel and other highly permeable materials (cracks in the formation) cause loss of working water and cannot be drilled. The borehole stays open by water pressure. To prevent collapsing fluid-drilled boreholes must be kept full of water during the entire drilling and well installation process.<br>- Enough working water needs to be available on the drilling location. <br>- Leaving the borehole open during the night has a risk of collapsing.<br>
- Slower than motorized drilling<br>
}}
==Technical specification==
====Operation====
Drilling is continuous: the drill bit is normally not removed from the borehole until it is finished or work is interrupted. As a portion of the drill stem is entered, another length of ¾” (19 mm) metal pipe with reinforced threads is screwed on. Drilling fluid (mud, a suspension of ordinary clay or bentonite with an adequate density) is pumped down through the drill stem using a hand-operated mud pump. The drilling fluid comes back up around the drill stem, carrying broken-up material. Sand and small stones settle in a settling area dug in the ground, and the mud is recycled through the pump.
Percussion action is performed by lifting the drill with a lever, mounted on the drilling tower, and letting it fall down. Moreover, the drill is rotated half-turns in both directions, enhancing the grinding action of the bit.
The resulting hole diameter is about two inches, and wells are cased with cheap 1 1/2” (39 mm) PVC pipe. This can accommodate a 1 1/4” PVC piston pump, but if required, the upper portion of the well (down to about 1 m below the lowest expected water table) can be reamed to accommodate larger diameter pumps. As the entire drill stem is metallic, the weight of the drill increases linearly with depth, so the deeper the well, the heavier the stroke, but stroke length is limited to about 30 cm by the lever.
No temporary casing is used. Upon reaching the desired depth, drilling fluid is removed from the hole by injecting progressively lower density mud. If unstable layers are present, however, this diluting can make the well collapse before it can be cased. In such cases it may be better to case the well with mud in it and evacuate the mud afterwards by pouring or injecting water into the casing (backwashing).
====Maintenance====
====Manufacturing ====
The complete rig can be built locally in about any arc-welding workshop, using only materials found in ordinary hardware stores.
==Country experiences==
The EMAS method is mainly used in Bolivia, Panama, Ecuador, Paraguay, Brazil, Peru, Honduras, Nicaragua, El Salvador, Guatemala, Eritrea and Sri Lanka.
==Manuals==
* EMAS have produced a set of DVDs which cover, among others EMAS drilling and other low cost water supply techniques. Contact Wolfgang Buchner on [email protected] if you would like to order a copy. The movies will also be made available on the web.
==Movies==
* [http://blip.tv/file/2445011 Standard EMAS well drilling, by Wolfgang Buchner]* [http://www.youtube.com/watch?v=nYNQt36VayM EMAS well drilling, by Wolfgang Buchner, Part 1](same movie as above)
* [http://www.youtube.com/watch?v=7jw1ZY1ccmo EMAS well drilling, by Wolfgang Buchner, Part 2]
* [http://emas.blip.tv/ Large collection of EMAS movies on different subjects.]==External linksLinks==* EMAS - [http://www.emas-international.de/english/index_e.htm Website of EMAS on EMAS well drilling]* Article on [http://www.emasrwsn.ch/documentation/skatdocumentation.2008-05-international28.de6936214484 EMAS drilling by Paul Cloesen] .* General info Rural Water Supply Network, [http://www.rwsn.ch/prarticle.2005-10-25.9856177177/prarticle.2005-10-26.7220595116/prarticle.2005-11-15.6127855822/prarticle.2009-05-11.3051371225/prarticle.2009-05-11.7567765725/prarticle_view article on well EMAS drilling ]. General [http://www.rwsn.org wwwch/prarticle.2005-10-25.9856177177/prarticle.2005-10-26.7220595116/prarticle.2005-11-15.6127855822/prarticle.rwsn2009-05-11.org3051371225 manual drilling section of RWSN website].
==References==
* This article is based on an [http://www.rwsn.ch/documentation/skatdocumentation.2008-05-28.6936214484 article ] by [http://geocities.com/paulcloesen/ Paul Cloesen], and on material from [http://www.emas-international.de/english/index_e.htm www.emas-international.de]