The pump creates a vacuum in the header pipe, drawing water up out of the ground. A typical wellpoint system consists of a series of small diameters wells (known as wellpoints) connected via a header pipe, to the suction side of a suitable wellpoint pump. In appropriate ground conditions a wellpoint system can be installed speedily and made operational rapidly. Wellpoint dewatering is widely used for excavations of shallow depths, especially for pipeline trench excavations. Groundwater Engineering provides complete deep well dewatering solutions: Water collection pipes, power supply generators, electrical controls and monitoring systems are located at the surface. The wells are generally sited just outside the area of proposed excavation, and are pumped by electric submersible pumps near the base of each well.

Because the technique does not operate on a suction principle, large drawdowns can be achieved, limited only by the depth of the wells, and the hydrogeological conditions. Several wells acting in combination can lower groundwater level over a wide area beneath an excavation. Pumping from each well lowers the groundwater level and creates a cone of depression or drawdown around itself. This is known as ‘pre-drainage’.Ī deep well system consists of an array of bored wells pumped by submersible pumps. 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. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used. Another form of rotary style drilling, termed mud rotary, makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to maintain borehole stability, regardless of the presence of a casing in the well. Air and/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling.

Some rotary drilling machines are designed to install a steel casing into the well in conjunction with the drilling of the actual bore hole. Rotary drilling machines use a segmented steel drilling rods, typically made up of 6 metres sections of galvanized steel tubing that are threaded together, with a bit or other drilling device at the bottom end. Water wells in some areas can go deeper than 900 metres. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Rotary can be used in 90% of formation types.ĭrilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Water wells are drilled to supply the ever growing need of the most essential element of life to humanity.ĭrilled wells are typically created using either top-head rotary style, table rotary, or cable tool drilling machines.

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