Dewatering and Groundwater Control for Basement Construction

Construction & Contractors Blog

The presence of water during excavations for basement construction is usually considered an inconvenience in construction. Groundwater does not create an ideal environment for excavation and other construction works. If not suitably managed, groundwater can cause significant problems and hitches in the excavation process, more so if the process involves deep basement construction. Adequate control and management of this water are essential for a successful basement construction project.

Problems associated with groundwater

If contractors undertake excavation without factoring in groundwater control measures, the following problems may be experienced.

  • Increased flooding of the construction area due to water seepage and inflow from the surrounding soil and water-bearing rocks.
  • Instability of excavation side slopes and base due to high water pressure. The excavation can even collapse altogether.
  • Reduced efficiency in construction operation due to hindrances from the seepage. You may be required to shift from using earthmoving equipment to submersible equipment which can work more efficiently.

Groundwater can change the course of the entire construction project. However, through dewatering techniques, you can be able to control it and resume normal basement construction.

Dewatering techniques

Dewatering involves the processes of reducing and intercepting groundwater on and around a construction site. The most efficient method off dewatering once excavation has commenced is sump pumping. In this technique, groundwater is allowed to seep into the site. It is then collected in sumps and pumped away.

Sump pumping is efficient when the amount of water that's collected on the site is not enough to cause instability to the excavation. Pre-drainage methods of dewatering can be applied to avoid the risk of too much water collecting post-excavation. The methods include:

Deep well dewatering

Deep wells are ideal for deep basement construction projects where the soil is highly permeable to water. In this system, various wells are bores, and each fitted with a multi-stage electric submersible pump. Water is then pumped simultaneously from each well, lowering the level of groundwater on the construction site substantially.

Horizontal well dewatering

Horizontal wells are suitable for sewers, cables, and pipeline excavations. In this case, specialized trenching machine systems are used to drain the groundwater from the soil. The water is then pumped out to lower the water table and modify the subsurface flow pattern for a dry excavation site.

Ejector well dewatering

Ejector wells are ideal for the control of groundwater in sites with soils of low permeability such as sand and silt. In this case, wells are drilled to lower the level of groundwater at the excavation site. Vacuum pumping systems are used to extract water from the soil by creating a vacuum area in the well.

Deep basement excavation can be a challenging project in the presence of groundwater. However, with these dewatering techniques, you can divert water from the site and smoothly proceed with the excavation project.


16 June 2016

Compelling and Creative Commentary on Construction and Contractors: A Blog

Welcome! My name is Frances, and this is my first blog. Whether you found me through a Google search or were passed my link by a friend, I am so glad you found my blog. I plan to fill it with a range of commentary on the world of contracting and construction work, and I hope that you find my ideas compelling and creative. I am a dog trainer, but I have always loved the world of construction. I tend to work a lot on the weekends and evenings, when my clients are off work. As a result, I have a lot of time to write during the day, and I decided to create this blog. Thank you for reading.