NASCLA Accredited Commercial General ContractorSite WorkMedium
A contractor is preparing a site for a new commercial building on a property with a high water table. To ensure a stable foundation, they need to temporarily lower the groundwater level during excavation and concrete pouring. Which dewatering method is most suitable for a large, deep excavation in permeable soil conditions?
- ASump pumping
- BEjector systems
- CDeep wells
- DWellpoints
Show answer & explanationAnswer & explanation
Correct answer: C. Deep wells
Deep wells are highly effective for lowering groundwater over large areas and to significant depths, especially in permeable soils. They use submersible pumps in drilled wells to draw down the water table, providing a dry working environment for foundation work.
Why the other options are wrong
- A. Sump pumping is typically used for collecting surface water or minor seepage, not for lowering a high water table over a large area.
- B. Ejector systems are used for lowering groundwater in very low permeability soils, which is not the condition described.
- D. Wellpoints are better suited for shallower excavations and less permeable soils than deep wells.
Deep Well Dewatering
A dewatering technique that uses submersible pumps placed in drilled wells to lower the groundwater table over a large area, particularly effective for deep excavations in permeable soils.
- Suitable for deep excavations and large areas.
- Effective in permeable soil conditions.
- Uses submersible pumps in drilled wells.
Memory trick: Deep wells for deep problems, wellpoints for puddles, ejectors for clay, sumps for surface play.