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[[Image:Rota_sludge_well_drilling_iconTreadle_pump_icon.png|right]][[Image:Diagram of a rota sludge.jpg|thumb|right|150px|Diagram of a rota sludge]][[Image:Rota sludge in action.jpg|thumb|right|150px|Rota sludge in action]][[Image:Deep drilling with the rota sludge.jpg|thumb|right|150px|Deep drilling with the rota sludge]]
[[Image:Rota_sludge_well_drilling.PNG|thumb|right|150px|Drilling a 20 m deep well in Chinandega, Nicaragua, with the Rota-sludge method ]]
[[Image:Rota sludge drill bit.jpg|thumb|right|150px|Rota sludge drill bit]]
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The Rota-sludge method Sludge is an adaptation of a manual drilling technique based on the Indian hand [[Sludging - Asian Sludge |Asian sludge method]] technique, and adapted for harder soil types. The To drill through the harder layers, a hardened drill bit and weight have been added. Just after the downward movement of the drill pipes the drill bit is turned 90 degrees during drilling rotated a quarter turn, thus chiselling the bottom of the hole. This technology can be used Water is circulated to bring the cuttings to drill 2-5 inch wells in layers with sand, clay, gravel, tuff stone or weathered rockthe surface.
During drilling, the drill pipe is moved up and down. On the down stroke, the impact of the drill bit loosens the soil and on the up stroke, the top of the pipe is closed by hand (or a valve), drawing up the water through the pipe and transporting the cuttings to the surface. On the next down stroke, the hand (or valve) opens the top of the pipe and the water squirts into a pit, in front of the well. In this pit, the cuttings separate from the water and settle out, while the water overflows from the pit back into the well.
The borehole stays open by water pressure. Thickeners such as clay, bentonite or even cow dung are usually added to the water in order to prevent hole collapse and reduce loss of working water (drill fluid).
==History and social context==
The Rota-Sludge was developed by the [http://www.practicafoundation.nl/products/drilling-wells/ Practica Foundation].
==Suitable conditions ==
{{procontable | pro=
- Easy to handle and a temporary casing is normally not needed. It is possible to construct the drilling equipment locally.<br>- Can drill through softer-consolidated formations.|con= - 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>- Coarse gravel and other highly permeable materials (cracks in the formation) cause loss of working water and cannot be drilled. If very fine sands (quick sands) are encountered in hard soil the first three meter of the borehole, a temporary casing and swell clay are needed on the outside of this casing to prevent collapse.<br>| con= - If cow dung is used as drilling fluid, this can cause contamination of the well, which can take several weeks to disappear.
}}
==Technical specification==
====Operation====
Cow dung is mixed with water to create a very low cost drilling fluid. It may take several weeks after the drilling is finished for the pathogens (bacteria) to die and disappear completely out of the well.
====Maintenance====
====Manufacturing ====
All drilling equipment is locally produced.
==Cost==
In India, the cost of a well made with Rota-sludge is about US$ 30.In Nicaragua, this varies from US$ 80 to US$ 400.
The cost of introduction varies between US$ 5,000-20,000 per project, including hand-on training, drill set and drilling of test wells.
==Country experiences==
The Rota Sludge is used in Nicaragua, Tanzania, Madagascar, Ghana, Senegal, Mauritania and Niger.
==Manuals==
*[http://www.practicafoundation.nl/wp-content/uploads/PDF/Practica%20drilling%20Rs%20versie%201th%20september%2005.pdf Rota-sludge and stone hammer drilling, Part 1, Drilling manual]. Produced by [http://www.practicafoundation.nl PRACTICA Foundation] and [http://www.etc-international.org/index.php?id=41 ETC Foundation].
*[http://www.practicafoundation.nl/wp-content/uploads/PDF/practica-production-rs-versie-1th-september-051.pdf Rota-sludge and stone hammer drilling, Part 2, Production manual]. Produced by [http://www.practicafoundation.nl PRACTICA Foundation] and [http://www.etc-international.org/index.php?id=41 ETC Foundation].
==Movies==
* [http://nl.youtube.com/watch?v=MvebFHCjCvk nl.youtube.com/watch?v=MvebFHCjCvk Rota sludge drilling in Madagascar , January 2008]
==External linksAcknowledgements==* The basis for the material on this page was obtained from a desk study shortly to be published on the website of the [http://www.practicafoundation.nl / Practica Foundation], and from the [http://www.practicafoundationrwsn.nlch/ Rural Water Supply Network]* General info on well drilling , and specifically its [http://www.rwsn.org wwwch/prarticle.2005-10-25.9856177177/prarticle.2005-10-26.7220595116/prarticle.rwsn2005-11-15.org6127855822 manual drilling section]. ==External Links==* [http://nlwww.youtubepracticafoundation.comnl/products/drilling-wells/watch?v=MvebFHCjCvk nlwww.youtubepracticafoundation.com/watch?v=MvebFHCjCvknl drilling section]* Organisation General info on manual well drilling [http://www.waterforallinternational wwwrwsn.ch/prarticle.2005-10-25.9856177177/prarticle.2005-10-26.7220595116/prarticle.2005-11-15.waterforallinternational 6127855822 Rural Water Supply Network]
==References==
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