Construction dewatering (2024)

FAQs

What is the dewatering method in construction? ›

Construction dewatering methods refer to techniques such as wellpoints, deepwells, bypass and flood control. In wellpoint and deepwells submersible pumps are installed in a drilled well shaft, while in bypass and flood control pumps are placed in the area that needs to be dewatered.

While dewatering can be a useful tool, there are also risks involved. If not done properly, dewatering can lead to instability of the ground and soil. This, in turn, can lead to sinkholes and other problems. There is also the potential for groundwater contamination if the water removed is not properly treated.

The dewatering process in construction sites involves the removal of groundwater or surface water from the workplace. The process is usually carried out by pumping or through evaporation before excavating the ground for footing. It also helps to lower the water table for rapid excavation.

Dewatering activities keep the ground in dry and stable conditions and help avoid water from damaging construction materials and equipment. Uncontrolled groundwater can lead to mudslides. Your building foundation may remain unstable, while construction equipment may fail due to bogging.

Volumetric method: This involves measuring the volume of a sample of the material being dewatered and then removing the water until the volume of the material is equal to a certain threshold value. The amount of water removed can then be calculated as a percentage of the original volume.

Open sump pumping is the most cost-effective and least complex dewatering method. It is perfect for removing water in shallow excavations that contain permeable soil with high levels of sand or gravel. A sump is defined as a depression or hole lower than the surrounding area where water is allowed to collect.

If your jobsite shows signs of erosion, stop dewatering. Avoid discharging contaminated water. Stabilize any channels used for dewatering. Avoid dewatering during heavy rains.

Lowering the water table reduces the moisture content in the top layers and will result in shrinkage. Lowering of the groundwater table by dewatering to provide dry conditions during work in large open excavations can lead to land subsidence or soil settlement.

The dewatering can either be gravity or a vacuum method to the desired extent. Groundwater can create a lot of problems like destabilisation of foundation, seepage into the structure, unequal settlement of the foundation, hence the structure may collapse.

How long do you let a dewatering system run before excavation begins? The run time depends on the soil materials. It can take anywhere from overnight to one week.

What are the basics of dewatering? ›

Sump pumping is the simplest and most common construction dewatering method using gravity to do the majority of the work. Groundwater is allowed to collect in shallow holes, or sumps, at the construction site. The collected water is then pumped out of the site.

We have singled out four commonly used methods: sump pumping, wellpoints, deep wells, and eductor wells. These techniques can be employed singularly or in combination depending on the nature of the soil and groundwater conditions.

The process typically involves sloping the areas of work to drain water away, pumping surface water to another location, or drilling a series of well-points into the ground around the area of work and pumping it to another location in order to artificially lower the water table while work is occurring.

The vacuum dewatering concrete is based on the principle of removing surplus water (or excess water). The concrete floor is dewatered by vacuum process wherein surplus water from the concrete is removed immediately after placing and vibration, thereby reducing the water cement ratio to the optimum level.