Every structure needs a solid foundation for stability; the soil where the structure is to be built must be stable first. A primary obstacle to constructing a solid foundation is the presence of excess groundwater in the soil. By default, the earth has water beneath it; that is why geography describes the earth to be made of 75% water.
This water in the earth tends to be overly concentrated in specific areas during construction. It often constitutes a serious problem for construction workers when working in water-logged areas.
This is why recent developments in construction technology have offered several techniques to reduce excess groundwater. The techniques are described as dewatering, and this article will explain the process of dewatering construction sites. Read on to learn more.
What is Dewatering in Construction?
Dewatering reduces the level of groundwater present in an area. This is made possible via specific dewatering techniques.
There are several dewatering methods; some use pressure to extract water present in the soil, while others use a gravitational pull and vacuum system. These methods include:
- WellPoint Dewatering Systems: wellpoint dewatering process involves installing wells around the construction area at a predetermined depth. Then with the aid of riser pipes, suction pumps, and header pipes, the water is extracted by the vacuum from the suction pipes through the riser pipes and channelled away from the construction area using the header pipes.Wellpoint systems are used to dewater excavations up to 4-5m deep. Deeper excavations may use a two stage dewatering system.
- Ejector well methods: the Venturi principle states, “when a high-pressure fluid flows through a narrow section pipe, its pressure reduces.” This method involves installing pumps at a single pumping section in the construction area and using Venturi riser pipes to extract groundwater. Since groundwater flows at high pressure, they are best for low-permeable soil at large depths.
- Open sump pump dewatering: this method involves creating sumps around the construction area. Groundwater is collected using gravity in the sumps and channels away from the construction area. This method is best for Sandy soils.
- Deep well-points method: this dewatering method is similar to the above-mentioned well-point system. However, this system is issued for large depths, and the wells are much wider. Specialised dewatering equipment is required for deep well point dewatering.
Steps to Take Before and During Dewatering Process
There are specific steps to take that ensure that your dewatering process is successful. They include:
- Water Testing: before taking the step to extract water from a construction site. It is essential to test the water for toxic or polluting elements. If the water is toxic or polluted, it should be collected for treatment. If not, the water can be used during construction.
- Get Permit: after examining the water, you must get a permit to practice dewatering. This permit will consider what you intend to do with the water collected from the construction area.
- Treat the water: after obtaining a permit and the result of the tests carried out on the water sample from the construction area. It is essential to treat the collected water.
Dewatering a construction site is essential for quality construction results, instruments, and workers’ safety. It is also critical for environmental protection. This article has briefly explained dewatering processes and the methods involved. We have also highlighted the steps involved to make it easier for you.