Dewatering is used to remove water from the deep soil. The water beneath the soil is not suitable for construction. You must know that the setting process of the cement is not possible in the presence of water, and to make the cement dry, displacement of the water from that region is essential. There are many techniques to cope up with this hurdle, and in this article, we will explain numerous methods of dewatering. These include sump pumping, deep-well construction, freezing method of dewatering, chemical consolidation, etc.
What is Dewatering?
If water is leaking into the ditch during foundation excavation, it’s vital to eliminate it. If water isn’t far away from the ditch, it isn’t easy to form concreting or masonry within the foundation. The process of removing water from the soil is known as dewatering.
Dewatering is required for the security of the structure around the pit within the following conditions:
• Deep excavation
• Construction in waterlogged area
• Pile Foundation
Methods of Dewatering
Following are different types of water removal services:
- Sump pumping:
In this method, water is removed by using the trench pumps. Generally, centrifugal pumps are more valuable. Hydrovac solutions work best in this regard. The sump pumping is used in water-logged areas which are shallow. The size of the ditch is usually 20cm in diameter.
The sumps are prepared at a distance of 40 m to 60 m in the ditches. Sumps are 1m x 1m x1m in size. The water flows into the ditches from where it is collected within the sumps. Then water is continuously pumped out from the sumps.
- Deep-well construction:
This dewatering method is more suitable when digging operation (trenching) is unsuitable to reach the water level, or artesian water is present in the soil. Following are the steps of deep-well construction:
- The 15 to 60 cm diameter casing pipe is inserted into the ground.
- At the bottom of the casing, a suitable filter layer or mesh is placed.
- A submersible pump is inserted at the bottom of the casing.
- The capacity of pumping must not be less than 30 cm.
- However, when the excavation is done in deeper soil, deep-wells are built at suitable spaces from the edge of the excavation.
- For each well, a separate pump is reserved.
- Freezing method of dewatering:
In this dewatering method, a wall of frozen clay is formed by freezing the moist soil of the project site where the excavation is performed.
The process is as follows:
- The 10-15 cm diameter pipes are inserted in the ground around the region where excavation is planned.
- These pipes are laid 1-1.5 m apart.
- The lower ends are closed.
- Then 5 cm diameter small pipes are placed, having perforation at the lower end.
- A single pipe connects the upper ends of all small pipes to the refrigeration plant.
- The 23-30°C cold water or other liquid is circulated in these pipes.
- The cold water runs out of a small pipe, ascends into a big pipe, and returns to the refrigeration plant.
- This results in freezing the moist soil, which then makes a frozen wall of clay.
- Well-Point System of Dewatering:
This dewatering solution is utilized for bottom water. The method is executed by diverting the flow into deep points of the well. By this, the part of the excavating area is kept undisturbed from spring water.
Well-points are prepared at a distance of about 1m around the excavation area.
- Cement grouting:
This method involves cement grout for dewatering purposes. It is a mixture of cement, sand, and water. In this method, several holes are made in the ground. Then cement grout is forcibly pushed into every hole. This is done until the grout comes out of the foyer. Importantly the cement grout is frozen in cracks and cavities, thus making the stone or clay monolithic.
Dewatering ensures the solid foundation of a construction site. Construction companies rely on water removal services because damp soil is highly unsuitable for construction projects. These dewatering methods ensure the safety of a construction site.