Changes

Sludging - Baptist method

176 bytes added, 03:11, 17 July 2012
no edit summary
In the unconsolidated formation types of Bolivia wells are drilled to depths of 20 and 60 meters on average. In the consolidated formations of Nicaragua, Ethiopia and Kenya well depths range from 10 – 15 meters on average. In exceptional conditions, boreholes up to 100 m deep have been drilled with this method.
 {{procontable | proborder="1" cellpadding="5" cellspacing="0" align="center"|-! width="50%" style="background:#efefef;" | Advantages! style="background:#ffdead;" | Disadvantages|-| valign="top" | - Very simple and cheap equipment. <br>
- Easy to handle and a temporary casing is normally not needed. It is possible to construct the drilling equipment locally.<br>
- continuous movement (compared to [[Hand auger - general|augering)]])
- Caving resistant borehole <br>
- Possible above and below the water table
|convalign= "top" | - 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 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>
- Suitable for unconsolidated rocks only (sand, silt, clay)<br>
- PVC drill stem needs to be of high quality<br>
- In wells deeper than 20m, a lot of manpower is needed to pull the rope
|}} 
==Construction, operations and maintenance==
Akvopedia-spade, akvouser, bureaucrat, emailconfirmed, staff, susana-working-group-1, susana-working-group-10, susana-working-group-11, susana-working-group-12, susana-working-group-2, susana-working-group-3, susana-working-group-4, susana-working-group-5, susana-working-group-6, susana-working-group-7, susana-working-group-8, susana-working-group-9, susana-working-group-susana-member, administrator, widget editor
30,949
edits