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[[Image:Icon_sludge.png|right]]

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Sludging is a manual drilling technique in which water is circulated to bring the cuttings to the surface. The drill pipes are 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.

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! width="50%" style="background:#efefef;" | Advantages

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| valign="top" | - Easy to handle and a temporary casing is normally not needed. It is possible to construct the drilling equipment locally.<br>