Hydraulic ram pumps and Sling Pumps

WaterAidCompletionAfter construction of the well shaft has beencompleted, the bottom is plugged withgravel. This helps to prevent silty materialfrom clay soils, or fines from sandymaterials, being drawn into the well. Anyannular space between the pre-cast caissonwell rings and theside of the excavation should also be filledwith gravel; such filling behind the ringswhich are below the water helps to increasewater storage and to prevent the passage offine silts and sands into the well.The space behind the top 3 metres, or so, ofthe well rings should be backfilled to groundlevel with puddled clay, or concrete, and thewell rings should project about 1 metreabove a concrete apron. This apron providesa sanitary seal to prevent polluted surfacewater seeping into the well and should slopeaway from it and drain into a channel whichdischarges into a soakaway.AbstractionIt is desirable for the well to have a concretecover slab, to reduce the possibility ofcontamination. Water is abstracted bymeans of either a bucket and windlass abovean access hole, or a hand-pump, depending upon the yield of water available and the ability of thebenefiting community to pay for ongoing maintenance for the handpump, spare parts, etc.http://www.wateraid.org.uk/site/in_depth/technology_notes/297.asp (3 of 4) [1/13/2005 12:48:44 PM]