Under this method, the water is released through storm drains, municipal sewer system and irrigation purposes.
The following methods are mostly used for dewatering :-
1. Open dewatering
2. Well point dewatering
3. Deep well dewatering
4. General sump pumping
Open dewatering system: It allows one to reduce the ground water table adequately in cohesive and low penetrable soils. Water is drained directly from sumps (ditches) along the toes of the slopes from the excavation works.
Well point dewatering system: It is performed by gravity or vacuum. This system allows one to reduce the ground water table adequately for deep and large construction. The water from high penetrable soils is drained from well points, set up along the trench of the site.
Deep well dewatering: This system allows one to reduce the groundwater table to substantial depth. A submersible pump is set up at the bottom of the well with casing containing a minimum 150 mm dia. The discharge pipes from the submersible pump of a number of adjoining wells are attached to a common delivery main. The water is uplifted from the well with the help of multi-staged pump.
General sump pumping: Sump pumps are suitable where excess water is drained from a specific area. They usually rest in a basin or sump that accumulates this excess water. This classification contains bilge and ballast pumps, centrifugal pumps, cantilever pumps, sewage pumps, submersible sump pumps and utility pumps.
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