Dewatering System
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The document discusses two methods for controlling water levels around excavation sites: deep well systems and wellpoint systems. Deep well systems use individual wells with submersible pumps that can lower water levels over 100 feet in depth, making them suitable for deep excavations. Wellpoint systems consist of multiple wellpoints connected to a common header and pump, allowing them to dewater sites where water needs to be lowered up to 20 feet. The deep well system is best for deep, homogeneous aquifers, while the wellpoint system works well in shallow aquifers requiring less lowering of the water table.
Dewatering System
- 2. The deep well system is also a versatile predrainage dewatering system which can pump high and low volumes of groundwater. This method is best suited to homogeneous aquifers that extend well below the bottom of the excavation. Deep well systems consist of one or more individual wells, each of which has its own submersible pump at the bottom of the well. Deep well systems are suitable for water-table or confined aquifers and will lower the water table 100 feet or more in a single lift without staging.
- 3. Advantages Deep Wells can be effective when placed outside of the jobsite work area Capable of pumping tens to thousands of gallons per minute per well Installation of up to 100 feet deep or more in a single stage Ability to penetrate strata impervious to the jetting method of wellpoint systems
- 7. The wellpoint system is one of the most versatile of pre-drainage methods which can pump a few gallons per minute in fine sandy silts or many thousands of gallons per minute in coarse sands and gravels. A wellpoint system consists of a number of wellpoints spaced along a trench or around an excavation site, all connected to a common header, which is attached to one or more wellpoint pumps. A wellpoint systems are most suitable in shallow aquifers where the water level needs to be lowered no more than 15 or 20 feet. Due to the vacuum limitation of the pump, excavations that are deeper will require multiple stages of wellpoint systems. When designing a wellpoint system, it is necessary to give first consideration to the physical conditions of the site to be dewatered.
- 10. Wellpoint System
- 11. Wellpoint System