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.

This solution is ideal when it is necessary to pump large amounts of groundwater or when significant drawdowns are required.

Deep Well System Design

Deep well systems are a gravity drainage system, typically consisting of widely spaced wells. 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.

1. The screen, filter pack, and pump size are designed to match the formation allowing each well to pump at its maximum
2. Deep wells are typically drilled to depths of 30-100ft
3. Equipped with pumps that can produce as little as 5gpm or as much as 1000+ gpm
4. Highly effective tool for multiple excavation depths in many different types of geology

Deep Well System Installation

1. Drill the borehole for deep well installation
2. Install deep well’s casing & designed screen into borehole
3. Place the well pack designed for the native formation
4. Develop well & install submersible pump
5. Set the header pipe
6. Start pumping
7. Optimize, monitor & adjust the system
8. Lower the water table
9. Excavate

Advantages & Limitations

Advantages

1. Work very well in high permeability soils
2. Not limited by suction lift or drawdown amount
3. Can be used to dewater deep excavations
4. Useful for large excavations due to the large cone of influence it creates
5. Can take full advantage of deep aquifers to produce significant drawdown

Limitations

1. Cannot lower water directly on top of an impervious surface
2. Not as useful in lower permeability soils due to tighter spacing requirements