Ejector Systems

Ejector dewatering system

Like the deepwell systems, the ejector or eductor system is based on wells that are drilled to lower the groundwater level to provide stable working conditions. Ejectors use air within the wells to produce a vacuum to draw water out of the soil.

The system works by circulating high pressure water which is fed from a tank and supply pumps at ground level down the well into the ejector nozzle and venturi located at the foot of the well. The flow of water through the nozzle generates a vacuum in the well and draws in the groundwater. It is then piped back to ground level and back to the supply pump for recirculation.

Why Use Ejector Systems?

Ejector dewatering systems work to control pore water pressure in low permeability soils so this method of dewatering is best suited for sites with soils such as silts and fine sands.

WJ has a wealth of expertise and a high reputation for installing and operating ejector systems for notoriously difficult projects. We are proud to have successfully carried out the UK’s largest project, (Conway Crossing), deepest (Moorgate shaft), longest (M3 drainage renewal), as well as one of the smallest projects (Troon manhole).

Range of application for ejector dewatering systems on construction projects (based on CIRIA 515, London 2000)