Constructing structures such as buildings, dams, and powerhouses need a firm base as a foundation and a successful dewatering process. The act of removing surface water from a construction site due to accumulated water is known as Dewatering.
In construction projects, the dewatering process is done before excavation through pumping or evaporation. Planning the right process of removing water from the soil is vital before proceeding in order to provide a safe workplace.
Process of Dewatering
Dewatering prevents any leakage of water and keeps the excavation bottom or trenches dry. Ensure a successful dewatering process by adopting the right method.
Water pumping or siphoning are common ways to get water from a selected area. Using drainage channels, it carries away water from the area to the discharge point. In order to minimize erosion and possible water velocities protection should be placed on drainage channels.
There are a wide range and different methods of applications for dewatering and this depends on the ground condition of the site. The most common and important dewatering methods are:
- Wellpoint Method
- Open Sump Pumping
- Deep Wellpoint Method
- Eductor Wells
Common Misconceptions of Dewatering
1. Dewatering is not necessary to control groundwater.
Some people believe that a construction site can still be safe and stable even if dewatering does not occur.
This misconception is completely wrong because if dewatering does not occur, an excavation site will not be dried out and stable. The primary objective of groundwater control is to dry up the soil which prevents excavation from flooding and makes it suitable for any type of construction. Before a construction excavation begins, the table level of groundwater should be lowered.
Expect several damages, injuries, and costs increase if the process is not implemented well.
Groundwater is controlled in and around the excavation through dewatering. It is necessary for a construction site to undergo the process of dewatering because of the following reasons:
- Water carries sediments and dry soil will reduce the risk of it carried off to the landscape
- Water pressure is controlled
- Improves safety for stable side slopes
- Prevents seepage erosion
- Reduces piping failure
- Reduces any pressure from the excavation surface
- Stabilizes the landscape
- Damages construction equipment
- Removes water and toxins
- Cuts down the risk of mosquitoes and pests
Avoid a wet and unstable ground that gives hazards for construction workers and impedes or obstructs their operation. Prioritize their health and understand the environmental regulations.
2. Deep well method of dewatering excavation is faster than sump pumping method of dewatering excavation.
Both deep well and sump pumping method are common and normal for the dewatering process. However, a deep well method is more complicated than the sump pumping method. Most construction workers would prefer sump pumping method for convenience, safety, and efficiency.
Creating deep wells causes groundwater to fall mainly because of gravity and installs wells that are drilled around the area that helps lower groundwater level. The accumulated water is then pumped out through a submersible or centrifugal pump. The deep well method is well known for deep excavations since a massive amount of water has to be drawn out from the ground.
The whole process of pumping and accumulating water usually takes a lot of time which makes the sump pumping method more efficient and faster. Sump pumping method is influenced by gravity, too. With the use of solid pumps, expect an easy discharge of water. The bottom of the sump is typically at a level lower than the excavation bottom and several sumps can be placed in the construction area is large.
3. Any area is suitable for the dewatering process.
Another common misconception is that dewatering can be done in a certain area as long as it has soil. On the contrary, it is crucial to choose the best location before discharging water in order to avoid the soil from eroding.
A variety of factors may cause erosion and controlling it is a big concern for most construction projects. The structure must be protected to minimize environmental risks in the surrounding area. Pay attention to signs of erosion in the chosen area. If erosion instability and erosion occur, discontinue the dewatering process. Dewatering is also avoided under heavy rains.
Study the water table conditions around the construction area for the plan to work.