Dewatering: Types & Benefits in The Building Industry

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

Reasons For Dewatering

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

Methods of Dewatering

There are various methods of dewatering that are adopted and deployed throughout the construction industry, all around the world. These include:

The deep well system

This method involves boring a hole between 16 cm to 72 cm 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 6 to 9 cm. 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

The vacuum dewatering system is similar to the wellpoint system, but uses a suction head and is used in fine non-adhesive soils like clay to deliver superior results. Another fact that distinguishes this method from the wellpoint 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 today, and 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 subsequent 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.

Benefits of dewatering

Dewatering is very important when undertaking construction projects located in a water-logged areas. Some of the major benefits of dewatering are:

1. It increases the stability of slopes by making them suitable for supporting structures.
2. It helps control hydrostatic pressure and water seepage.
3. It is used to increase the effective weight of soil and strengthen soil layers.
4. It reduces the lateral load on sheeting and bracing.
5. 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 used throughout the building industry, by many fuel system maintenance and installation companies, including the The PSA Group. Different methods of dewatering are implemented, depending on the project requirements and prevalent environmental conditions. Some of the most common methods are highlighted in this article above.

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