Groundwater Control or DewateringGroundwater control or dewatering is the temporary reduction of pore pressures or groundwater levels to provide dry, stable and safe soil conditions in excavations below groundwater level. Dewatering is used to facilitate the construction of the deep excavations that are required for lift stations, tunnels and other underground structures.
Wellpoint DewateringWellpoint systems are used to lower groundwater levels to provide stable working conditions in excavations. Wellpoint systems are particularly suited for shallow foundations, utility and trench work dewatering.
A wellpoint system consists of a series of closely spaced small diameter shallow wells. The wellpoints are connected to a common header pipe and are pumped with a high efficiency vacuum dewatering pump. For drawdowns in excess of 15-feet, further stages of wellpoints are required and installed at successively lower levels as excavation proceeds.
Ejector (or eductor) dewatering systems are used to control pore pressures and to lower groundwater levels to provide stable working conditions in excavations. Ejector systems are able to extract groundwater and generate vacuum at the tip of wells and can be installed to depths in excess of 50-feet. Vacuum drainage can dramatically improve the stability of silty fine sands and laminated silts and clays by controlling excess pore pressures.
Supply pumps at ground level feed high-pressure water to the ejector nozzle and venturi located at the tip of the wells. The flow of water through the nozzle generates a vacuum in the well and draws in groundwater.
Deep well dewatering systems are used to lower groundwater levels to provide stable working conditions in excavations. A deep well system comprises of an array of drilled or jetted wells, each fitted with an electric submersible pump.
Deep Well Dewatering
This technique is particularly suited to deeper excavations or where artesian groundwater pressures threaten base stability. The system is reliable and the wide spacing of the wells reduces access restrictions to a minimum.
Project: 12-inch Dewatering Pump Hibbing, MN
Dewatering is the process of lowering the ground water table to allow for underground excavations that otherwise could not take place. The impact of groundwater on a construction project can be enormous. Unforeseen groundwater problems can cause major delays and often require drastic redesigns of the project itself.