Deep Well Dewatering Systems tend to be used where the excavation depth exceeds the maximum limits for a wellpoint system and a large quantity of water needs to be extracted. They are ideal for keeping water away from construction trench areas enabling work to be carried out in dry and stable conditions. A deep well system would be also be used if space is limited as deep wells can be sited away from the construction area.
- Drawdown only limited by depth of well and soil stratification
- Pressure relief can be provided in deep layers
- Wells can placed away from working areas (at the top of batters for example)
- Wells are usually installed at relatively wide spacing which minimises surface access restrictions.
- Relatively high installation costs per well
- Comprehensive, good quality site investigation information required for design
- Flexibility of equipment is restricted because individual pumps cover limited range of flow and discharge head
- Pumps are electrically powered so both duty and standby power supplies are required for reliability.