[[Image:Treadle_pump_icon.png|right]]
[[Image:Emas0.jpg|thumb|right|150px250px|Emas well drilling]]
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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.
==Suitable conditions ==
[[Image:Emas.jpg|thumb|right|150px250px|Drilling a well in Colombia with the EMAS method.]][[Image:Emas1.png|thumb|right|150px250px|All the equipment needed easily fits on a small hand-cart.]]
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).
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. For a 20 m well, one or two barrels are needed, or about 10-20 liters per meter.
{{procontable | pro=
|con=
- Generally limited to sandy soils and soft clay.
- 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 specificationConstruction, operations and maintenance==[[Image:Emas2.png|thumb|right|150px250px|Setting up the light-weight drill tower.]][[Image:Emas4.png|thumb|right|150px250px|Installing the lever, used to move the drill stem up and down.]]
Soft Clay is the easiest to drill, is suitable conditions 40 meters can be drilled in this material in one single day. For every meter, between 10 and 20 litre of water is needed, inlcuding washing. For a 20 meter well, one or two barrels of water are enough.
====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.
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====
[[Image:Emas3.png|thumb|right|150px|Drilling in process: one person operates the lever, one person guides the drill stem and rotates it, the third person operates the mud pump.]]
[[Image:Emas5.png|thumb|right|150px|The mud pump in close-up.]]
====Manufacturing ====
The complete rig can be built locally in about any arc-welding workshop, using only materials found in ordinary hardware stores.
[[Image:Emas3.png|thumb|right|250px|Drilling in process: one person operates the lever, one person guides the drill stem and rotates it, the third person operates the mud pump.]]
[[Image:Emas5.png|thumb|right|250px|The mud pump in close-up.]]
==CostCosts==[[Image:Emas6.png|thumb|right|150px250px|The well screen, slits cut with saw, end capped. Later, a sock is pulled around the screen.]][[Image:Emas9.png|thumb|right|150px250px|After the well screen is put in the well, the well is developed by a special tool.]]
An EMAS drilling rig, fit to drill holes up to 30 m deep, can be built in Bolivia for about US$ 600 - 800. This includes the tower, mud pump and all essential non-common tools to operate and maintain it.
The average well depth in Bolivia is around 27 meters, and costs approx. US$ 180 including an [[EMAS pump|EMAS hand pump]]. This makes a surface covering supply of drinking water possible for municipalities and families in rural areas.
==Country Field experiences==
The EMAS method is mainly used in Bolivia, Panama, Ecuador, Paraguay, Brazil, Peru, Honduras, Nicaragua, El Salvador, Guatemala, Eritrea and Sri Lanka.
==ManualsReference manuals, videos, and links==
[[Image:Emas8.png|thumb|right|150px|Putting in an EMAS flexi-pump.]]
[[Image:Emas7.png|thumb|right|150px|Wetting the cement for the pump base.]]
* EMAS have produced a set of DVDs which cover, among others EMAS drilling and other low cost water supply techniques. [http://emas.blip.tv The movies are available here]. Contact Wolfgang Buchner on
[email protected] if you would like to order a copy of the movies on DVD.
==Movies==
* [http://blip.tv/file/2445011 Standard EMAS well drilling, by Wolfgang Buchner]
* [Required materials for standard EMAS well drilling]
* [http://emas.blip.tv/ Large collection of EMAS movies on different subjects.]
==Links==
* The Technology Demonstration Center EMAS works with EMAS Jetting. See [[Technology Demonstration Centers]]
* EMAS - [http://www.emas-international.de/english/index_e.htm Website of EMAS on EMAS well drilling]
*[[Solution_of_the_week_11|Akvo solution of the week 11]]
==ReferencesAcknowledgements==
* 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]
