Firm and sound ground conditions are a must during the construction of buildings, roads and other civil engineering projects. These structures need a firm base for foundations, free from soft or waterlogged soil, and with a stable water table. The groundwater level plays a vital part in the stability of foundations. If the water table lies close to the base of footings, the bearing capacity and settlement characteristics of the soil can be affected.

Continuous rain or flooding makes the groundwork difficult and can undermine the foundations before they cure. Although the foundation’s structural design can overcome foundation problems, operations in waterlogged conditions cause disruption and delay. Dewatering pumps provide an effective solution during the construction process.

The Importance of Dewatering

Dewatering removes water from the workspace, either temporarily reducing the groundwater level or permanently removing excess water from site. The process is necessary before, during and after the construction stage. Dewatering provides a dry construction area and allows work to proceed efficiently. It also increases the stability of the sidewalls of an excavation, reducing the threat of collapse, and controlling the seepage of water and sand.

Choosing a Dewatering Method

Dewatering during construction has existed for a long time, and several techniques have been created to reduce the water table. Many companies enlist the help of industrial water pump suppliers to provide advice or implement dewatering. Other methods for dewatering include cut-off walls, siphon drains, water eductors and deep wells.

Selecting a method suitable for excavation depends on the location, size, type and depth of the excavation; thickness and permeability of the foundation soils; potential damage should the dewatering system fail; and the cost and installation of the system.

Make sure to include these factors during your project planning so that you do not encounter surprises and costly delays. Adding a risk assessment plan also allows you to identify existing or potential adverse effects you’ll encounter during the project.

Environmental Precautions

Readying the construction site

Dewatering must be done correctly to avoid soil erosion on the site. By disposing of water the wrong way, you also run the risk of breaching environmental controls. Water from excavation sites could get mixed with cement, machinery oil and mud, causing a source of pollution. Discharging groundwater to smaller water bodies also adds to the risk of flooding elsewhere.

When planning for dewatering, make sure to comply with the Resource Management Act, which lists guidelines for taking, diverting and discharging water. The rules allow dewatering without consent, but only if the process is unlikely to cause harm to the surface or groundwater. In other cases, the government requires more specialised protective measures before allowing the process to begin.

Dewatering a construction site is necessary to keep the soil dry, ensure the smoothness of operations and to maintain the safety of workers. Careful planning is recommended beforehand to make sure you’re familiar with the site and soil conditions, the right dewatering technique to use, and necessary legal requirements. This will result in a solid foundation for your construction project – both figuratively and literally.