seth@tkflow.com 
Dewatering is the process of removing groundwater or surface water from a construction site using dewatering systems. The pumping process pumps water up through wells, wellpoints, eductors, or sumps installed in the ground. Temporary and permanent solutions are available.
Importance of Dewatering in Construction
Controlling groundwater in a construction project is critical to success. Water intrusion can threaten ground stability. The following are benefits of construction site dewatering:
Reduce costs & keep project on schedule
Prevents water from affecting jobsite and unexpected changes due to groundwater
Stable Worksite
Prepares soil for construction mitigating risks associated with running sand
Excavation Safety
Provides dry working conditions to ensure personnel safety
Dewatering Methods
Working with a groundwater control specialist is essential when designing a pump system for site dewatering. Improperly designed solutions can result in unwanted subsidence, erosion, or flooding. Professional engineers evaluate local hydrogeology and site conditions to engineer the most effective systems.
Wellpoint Dewatering Systems
What is Wellpoint Dewatering?
A Wellpoint Dewatering system is a versatile, cost-effective pre-drainage solution that features individual wellpoints which are closely spaced around the excavation.
This technique utilizes vacuum to assist in lowering groundwater levels to create a stable, dry working environment. Wellpoints are especially suited to shallower excavations or excavations taking place in fine-grained soils.
Wellpoint System Design
Wellpoint systems consist of a series of small-diameter wellpoints installed at a pre-determined depth (usually 23ft deep or less) on relatively close centers. They are quick to install & can handle a wide range of flows.
The pump serves three basic functions:
√ Creates vacuum & primes the system
√ Separates air/water
√ Pumps water to the discharge point
Advantages & Limitations
Advantages
Quick installation & easy maintenance
√ Cost-effective
√ Used in low & high permeability soilds
√ Suited for shallow aquifers
√ Limitations
√ Deep excavations (due to suction lift limits)
√ Lowering water table near bedrock
Deep Well, Dewatering Systems
What is Deep Well Dewatering?
Deep well dewatering systems lower groundwater using a series of drilled wells, each fitted with an electric submersible pump. Deep well systems are often used to remove water from pervious formations that extend well below the excavation.Systems are designed to pump large amounts of groundwater, which creates a broad cone of influence. This allows wells to be placed on relatively wide centers and requires that they be drilled much deeper than wellpoints.
Advantages & Limitations
Advantages
√ Work very well in high permeability soils
√ Not limited by suction lift or drawdown amount
√ Can be used to dewater deep excavations
√ Useful for large excavations due to the large cone of influence it creates
√ Can take full advantage of deep aquifers to produce significant drawdown
√ Limitations
√ Cannot lower water directly on top of an impervious surface
√ Not as useful in lower permeability soils due to tighter spacing requirements
Eductor Systems
Wells are installed and connected to two parallel headers. One header is a high-pressure supply line, and the other is a low-pressure return line. Both run to a central pump station.
Open Sumping
Groundwater seeps into the excavation, where it’s collected in sumps and pumped away.
Post time: Oct-24-2024