Dewatering refers to the process that facilitates the removal of groundwater, as well as superficial water from the construction site. Dewatering is often done before excavation processes kick-off, and in other cases, it’s done to lower the construction site’s water table. There are different dewatering methods used in the construction industry, but first, it’s worth not that the removal of water from construction sites is important for the protection of construction materials, and also for the safety of the workplace. And with the accumulation of water in excavations and trenches, dewatering is a crucial process.
Below, we look at some of the ways that dewatering could be done or take a look at this website.
Dewatering Methods
1. Wellpoint
In this method, there is a series of wells that are aligned all along the excavated area. The well points are then connected to the riser pipes, which will then be connected to the common header pipe and the vacuum pump. The water from the excavation area will then be discharged off the site using an adequate amount of treatment enough to remove all unwanted materials and contaminants. Wellpoint uses suction, which makes it an ideal choice for dewatering construction sites with a depth of 5 or 6 meters. For deeper drawdowns, there will be multiple stages of the wellpoint.
2. Eductor Wells
The other dewatering process/technique for a construction site is the Eductor Wells. It’s quite similar to the Wellpoint method, with the only difference between the two being the fact that the Eductor Wells method makes use of high-pressure water rather than a vacuum to draw off water from the well points. It makes use of the venturi principle in these two steps:
The high-pressure water will be circulated through the eductors at the base of each well, hence the reduction of pressure. With the pressure drop, water will be drawn up through the riser pipe.
Using this method, the water table would be lowered down to a depth of between 10m and 45m, with multiple pumps operated from one station. This method is ideal for silts and clays, as well as all other low-permeability materials.
3. Deep Wellpoint
This method makes use of boreholes with the submersible pumps to ensure the lowering of the groundwater level way below the excavation level. With this technique, 15 or 20cm wells are drilled throughout the excavated area, and the groundwater will fall from gravity, in the process, lowering the water table and getting rid of all the groundwater around the excavated area. For the retention of the well, casings come in handy, as well as filters and screen, which will keep out sediments. If you’re working on a construction site that has a lot of water accumulated, the deep wellpoint dewatering method will ensure the removal of the water from the well.
4. Sump Pumps
The sump pumping is the most popular dewatering technique as it makes use of gravity, and also because it’s one of the most economical methods for construction sites’ dewatering.
With the sump pumps, the groundwater seeps straight into the excavation area where it’s collected into the sumps before it’s pumped out. Sump pumping is ideal for the shallow excavation areas, especially where the soil ha a high sand/ gravel content. In cases where the excavation area is significantly large, a ditch could be used, along with a narrow/long sump in the excavation.
These dewatering techniques will ensure the safety and stability of your construction projects.
