Well points are shallow wells and go around the perimeter of the site. A well point system consists of several well points spaced around an excavation site or along a trench, all connected to a common header which is fixed to one or better point pumps.
Also, well point assemblies-made up of a well point, riser pipe, screen as well swing joint with tuning-are installed by jetting. In addition to this, they provide for entry of water into the system by making of a partial vacuum. After that, the water is pumped off through the header pipe.
A well point pump is a combination of two pumps- The first one pumps water from the header while the other is a vacuum pump to remove air. Control of the air is very vital because excessive air causes cavitation that can reduce pump efficiency later.
The dewatering pumps used are designed specifically for the dewatering function and are available in sizes from 4” to 10” with handling capacity up to 500m3/hour.
Well Point Cape Town systems are both practical and effective under most soil as well as hydrologic conditions. Wellpoint systems are often the logical and affordable option for dewatering construction sites where the needed lowering of groundwater level is on the order of 6 meters or less.
By lowering the water in 2 or more stages, greater lifts are possible. The 6 meter lifts restriction outcomes from the fact that the water is lifted by the difference between the lowered pressure and ambient air pressure created by the pump.
Well points are set apart at intervals of from 1 to 3 meters in a typical system. The depth to which a well point is sunk into the ground is determined by the nature of the subsurface soil. However, the size and number of pumps, the diameter of risers and headers, the number and type of well points, the number and location of valves would only be found out after a thorough study of the hydrogeological conditions at a particular site have been done.
What Site Managers Must Collect Before Implementing A Wellpoint Dewatering Solution?
Before implementing a wellpoint dewatering solution, site managers must collect information like the nature of the soil, proposed methods and techniques of excavation and ground support, groundwater hydrology, Size and depth of the planned excavation, nearness to and foundation details of any existing structures, design and function details of the structure to be built and planned construction schedule.
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