Dewatering involves controlling groundwater by pumping, to locally lower groundwater levels in the vicinity of the excavation. It can be used as an alternative to, or in combination with, cut-off walls to exclude groundwater.
The simplest form of dewatering is sump pumping, where groundwater is allowed to enter the excavation where it is then collected in a sump and pumped away by robust solids handling pumps. Sump pumping can be effective in many circumstances, but seepage into the excavation can create the risk of instability and other construction problems.
To prevent significant groundwater seepage into the excavation and to ensure stability of excavation side slopes and base it may be necessary to lower groundwater levels in advance of excavation. This is known as ‘pre-drainage’. Pre-drainage methods include:
Other specialist dewatering techniques are also sometimes used:
The selection of the dewatering technique or techniques at a particular site or country will depend on many factors. Groundwater Engineering’s team has decades of experience in dewatering projects around the world, and we provide a complete design and installation service to control your groundwater problems.