Slurry Trenching (Walls)
Engineered trenching method for groundwater control and containment
Overview of Slurry Trenching (Walls)
Slurry trenching is a construction technique used to install vertical cutoff walls for groundwater control and containment. The method involves excavating a narrow trench under slurry. The fluid pressure in the slurry balances the lateral earth pressure in the soil permitting a stable excavation of a deep, narrow trench without the need for conventional shoring or dewatering.
After excavation, the trench is backfilled with low-permeability or reactive materials to form a continuous barrier. Common low permeability backfill types for two stage installations include soil-bentonite and soil-cement-bentonite. In other cases, the slurry can be used to support the trench and serve as the final cutoff wall material. These types of slurries are called self-hardening slurries as the material hardens in place after excavation is complete. Cement-bentonite is a common slurries used in this application though different cements and clays can be used. Slurry trenching has been widely used in North America since the 1970s and remains the preferred and most cost effective method for installing deep, narrow cutoff walls.
Geo-Solutions has completed 1000s of slurry trenching projects, including some of the deepest cutoff walls installed (up to 185 feet). The company has also pioneered the use of alternative slurries with polymers, different materials such as attapulgite clay, special cements, and silicates for challenging site conditions, and mixtures to accomplish extremely low permeability.
Key benefits
- Effective groundwater control without the need for dewatering
- Very low permeability barriers for seepage and contaminant migration control
- Adaptable to challenging conditions, including unstable soils and contaminated groundwater
- Proven performance with over five decades of successful installations
- Customizable backfill options for strength, chemical resistance, and permeability requirements
Applications
- Environmental Remediation: Containment of contaminated groundwater and pollutants
- Dam and Levee Seepage Control: Cutoff walls for seepage reduction in embankments
- Industrial and Infrastructure Projects: Groundwater barriers for excavations and foundations
- Mining Operations: Control of water inflow and contaminant migration in tailings and pits
- Reactive Barriers: Incorporation of treatment media for in-situ groundwater remediation
Groundwater Control
Groundwater control refers to methods that address seepage, hydraulic pressure, and subsurface water movement that affect excavation safety and structural performance. Cutoff walls and deep drains are common solutions used to manage groundwater in complex site conditions.
environmental remediation
Environmental remediation refers to methods for isolating, stabilizing, and treating contaminated soil, sediment, and groundwater. In situ stabilization and solidification performed using soil mixing is a common environmental remediation approach.
Ground improvement
Ground improvement refers to methods used to improve (often strengthen) weak, compressible, variable, or undesirable soils for specific performance enhancement. Soil mixing and rigid inclusions are common ground improvement solutions used to control settlement and improve subsurface behavior.
Cutoff walls
Cutoff walls are low permeability vertical elements installed in the subsurface to control horizontal groundwater flow and limit contaminant migration. Common technologies for installing cutoff walls include slurry trenching and soil mixing.
slope stability
Slope stability refers to methods used to resist lateral movement of slopes during loading or unloading, above and below the slope respectively. Shear walls installed via soil mixing are a common ground improvement system used for slope stabilization.
bearing capacity improvement
Bearing capacity improvement refers to methods used to increase the load‑carrying capacity of weak soils. Soil mixing and rigid inclusions are commonly used to improve bearing performance and reduce settlement.