Washington's horizontal drain applications concentrate on the Cascade Range's volcanic ash-derived soils, which lose strength dramatically when saturated by the region's persistent marine-influenced rainfall, making drainage a particularly high-value intervention for WSDOT's mountain corridors.
This pattern is consistent with the broader Steep Slope Stability Issues challenges GSI addresses across the state.
Horizontal drains bored into Washington's volcanic ash slopes intercept the persistent marine-influenced rainfall infiltration this soil type is especially vulnerable to. GSI's horizontal drains capability supports this step.
Reducing pore water pressure in Washington's ash-derived soils delivers an outsized factor-of-safety improvement given how dramatically this material weakens when saturated. This is one application of GSI's broader soil nailing expertise.
GSI pairs horizontal drains with soil nailing on Washington's steepest Cascade slopes where drainage alone cannot fully offset volcanic soil's saturation sensitivity. GSI's landslide emergency response experience informs this approach.
This approach is informed by GSI's broader engineers work across Washington.
Engineered for Washington's conditions. GSI prioritizes horizontal drains on Washington's volcanic ash soils, where drainage delivers unusually high stabilization value given this material's saturation sensitivity. It's backed by GSI's broader general contractors and our case studies capability.
Design/build delivery. One team carries the project from design to install — eliminating coordination gaps between engineering and construction.
WSDOT specification compliance. Documentation and field practices satisfy state DOT specifications from the first review cycle.
GSI's engineers are ready to assess horizontal drains conditions at your Washington site.
