Dewatering: Benefits & Uses In Construction Industry

By Author: Andrew Bain
Total Articles: 72
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Dewatering is the process of removing excess water from solid material or rock surfaces. The dewatering process is adopted for surfaces with excess water like a marsh, foundation trenches, and grounds with a high water table. There are different processes used in different dewatering methods, and they are:

Wet classification
Centrifugation
Filtration

Benefits of dewatering in construction

It allows for an efficient flow of construction work by providing dry ground for digging.
It makes sheeting and bracing easy by reducing lateral load or resistance.
It prevents piping and frosting in pavements by cutting off the capillary rise.
It reduces air pressure in the operation of tunnels.
Dewatering before excavation increases the strength and stability of slopes and side-hill fills.
It improves the supporting characteristics of foundation materials.

Methods of dewatering

There are various methods of Dewatering that is adopted in construction. They include:

The deep well system: This ...
... method involves boring a hole 15cm to 70cm in diameter using a case. This case possesses a long screen and submersible pump that is used to lift the water. This method is mostly adopted for excavations with depths of 16m below the water table.
The Wellpoint system: This method adopts the principle of gravity flow, and it involves using a perforated flow of a length of 0.5 to 1m and a diameter of 5 to 8cm. It also uses a cylindrical wire gauge and a suction pump. The suction pump sucks water from a depth of 6meters at most, bringing it to the surface. If the water depth exceeds 6meters below the water table, a good multistage system is used.
Vacuum Dewatering System: For better Dewatering, this system is similar to the good point system but uses a suction head and is used in fine non-adhesive soils like clay. Another fact that distinguishes this method from the good point system is the use of airtight seals on all points of the pipes to maintain a vacuum.
Ditches and Sumps: This is the simplest method in use, and it is adopted on a larger scale for shallow and coarse-grained soils. In this system, sumps or pits are dug, and the excess water is collected using the side currently under gravity. And the water is pumped out.
Electro osmosis dewatering: This method applies both electrolysis and osmosis in dewatering, and it is best adopted for fine-grained cohesive soils. It involves traveling soil water between electrodes, from the positive electrode to the negative electrode. The positive electrode or anode can be a pipe, sheet pile, or steel rod, while the cathode is a metal hose or a well used to pump out water.

Importance of dewatering

Dewatering is very important when constructing in a water-logged region. Some of the major importance are:

It increases the stability of slopes by making them suitable for supporting structures.
It helps control hydrostatic pressure and water seepage.
It is used to increase the effective weight of soil and strengthen soil layers.
It reduces the lateral load on sheeting and bracing.
It allows for excavation and construction to be done in a dry environment.

Conclusion

Dewatering is a process that permits excavation and construction to be done at natural ground level and is widely deployed by all major construction, engineering and maintenance companies around the world, including The PSA Group. It employs different methods to achieve this goal. Some of the most common methods are highlighted in this article above.

Managing director of leading Australian cleaning company, Worth Every Cent Cleaning.