What is dewatering?
Dewatering is a technique used to control groundwater on a jobsite. In layman’s terms, it’s the nontoxic process of separating solid waste from sludge and temporarily lowering groundwater levels for drier and more stable working conditions. The unpredictability of storms and rainfall makes dewatering tanks an essential piece of equipment for any outdoor project. Without them, jobsites flood, work stalls and projects get delayed.
What are the benefits of dewatering?
Dewatering can refer to draining underground water, which helps dry the soil to make it more suitable for construction or draining retention ponds and other bodies of water. Water can damage construction equipment or slow down operations. Dry soil reduces the risk of sediment being carried off by water and helps to stabilize the landscape. The presence of water can also obstruct certain site tasks, such as pouring concrete.
Having water on the worksite can also produce unsafe working conditions. Not only is groundwater a slipping hazard for workers, but standing water is a breeding ground for mosquitoes and other pests. Dewatering tanks help eliminate these issues, safeguard your workers' health, follow environmental regulations and keep your project on track.
What are the most common dewatering methods?
Generally, there are four different procedures used for construction dewatering. Each method is used for a specific application, so choosing the right technique for the job is vital.
- Sump pumps: Sump pumping is considered the most simple and common dewatering method. You allow groundwater to flow into the excavation area, where it is collected in sumps to be pumped out. Sump pumping is best applied in shallow excavations containing a high gravel or sand content.
- Wellpoint: The wellpoint method includes hooking up a series of wells via a riser pipe, which are then connected to a header pipe and vacuum pump. The liquid is then suctioned offsite and treated to remove contaminants. Since this dewatering system uses suction, it is most suitable for depths of up to 20 feet.
- Deep wellpoint: This procedure uses boreholes in tandem with submersible pumps, lowering the groundwater level beneath the excavation. Small wells are drilled all around the excavation, where liquid naturally flows with gravity. This lowers the water table and drains groundwater from the excavated area.
- Eductor wells: This practice is similar to the wellpoint method, except it uses high-pressure water instead of a vacuum. This method can be used at depths of up to 150 feet and is ideal for materials like clay with low permeability.
For more information on choosing a dewatering system, check out "Tips for Choosing a Jobsite Dewatering System."
The environmental benefits of dewatering
Environmental protection plays a key role in most markets and industries these days, including construction. With the government imposing stricter laws around wastewater disposal, it is more important than ever that we find environmentally friendly solutions for its elimination. Dewatering is an eco-friendly and economical solution for many companies.
It makes sense that dewatering helps clean up the environment since it removes harmful waste and toxins from the water. But one thing you may not have considered is that this filtered water can be reused on the site itself or for other purposes. This saves on the cost of using water from mains or other sources such as rivers. All this while lowering the labor and transportation costs of freshwater to the jobsite. Don’t let the rainy weather get the best of your construction site.