Dug wells or open wells are constructed by open excavation to tap the unconfined aquifer and have restricted application in semi permeable hard formation. The depth and diameter of the dug well are decided with reference
to the area of seepage exposed for intercepting the required yield from the saturated subsoil layers. Unsafe quality of water may result if proper care is not taken in the well construction. It is necessary to provide a watertight well-steining up to 3 to 6 m depth from the ground level or up to hard formation to protect from caving and also to prevent polluted water entering the well. The steining of the well should be extended about 1.0 m height above the ground surface and a watertight cover should be provided on the top of the well to avoid pollution from the atmosphere.
Location of the Dug Wellsopen well
The location of the dug well has to be fixed after conducting the geophysical survey to find out substrata features. Based on the findings of the geophysical survey, trial bore is to be drilled at the selected location for confirming the findings of the survey. Based on the strata details obtained from the trial bore, the dug well should be excavated. The site for the well should be far away from the point of disposal of sewage effluent; a minimum distance of 15 m from such points is essential to prevent contamination of well water.
The diameter of the open well range from 1.2m to 6m and depths ranges from 5 to 10m. The larger diameter provides a reservoir of adequate volume for storage of water within a least depth of the well.