A Wellpoint Dewatering system is a versatile, cost-effective pre-drainage solution that features individual wellpoints which are closely spaced around the excavation.
This technique utilizes vacuum to assist in lowering groundwater levels to create a stable, dry working environment. Wellpoints are especially suited to shallower excavations or excavations taking place in fine-grained soils.
Wellpoint systems consist of a series of small-diameter wellpoints installed at a pre-determined depth (usually 23ft deep or less) on relatively close centers.
The pump serves three basic functions:
Wellpoint systems are limited by suction lift and can only lower water below grade to a certain point (depending on the altitude). Systems are often installed as a Single-Stage or Multi-Stage because of these limitations:
When excavations are 18ft deep or shallower, one row of wellpoints may be used to draw the groundwater below subgrade. Careful consideration should be given to the project altitude as higher altitudes will mean less available drawdown.
Wellpoints can be used on much deeper excavations, but multiple stages are required. If necessary, two or more rows of wellpoints are installed at different elevations. This is needed when the excavation is deeper than 18ft or when the altitude would prevent dewatering with a single wellpoint stage.
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