A torrential late spring rainfall that dropped a deluge of water in upwards of 10 inches over a short period of 36 hours caused a dirt retaining wall below the deck area of this residence that is built on a steep incline area, to slough off. The heavy down rush of water and resulting landslide, ripped out a portion of the home’s deck and board walk area. Water and rock chunks that broke loose carried soil away, leaving voids and unstable areas on the steep slope directly below the home and creating an unstable situation.
The homeowner was not only concerned about the stability of the area, but planned on rebuilding the deck and boardwalk that had been destroyed during the slide. In order to do so, the retaining wall and slope would need to be re-compacted and any void areas filled and stabilized in order to make the area safe and strong enough to hold up during future water events and to support the reconstructed deck and walkway.
Factors for Consideration
The homeowner planned to rebuild the deck and boardwalk area that was washed out during the heavy rain. The steep slope would need to be reinforced to ensure a safe, stable area to rebuild on and that would withstand additional water flow and remain stable for years to come. The safety of CST’s crews who would perform the void fill and stabilization of this steep incline was a major factor. Technicians used extra fall protection and tie off methods to ensure their safety during the project.
The CST technologies were used to stabilize the weakened and loose soils on the entire length and width of the slope.
The CST deep injection process which involves injecting expanding structural polymer at different depths directly into the soil was used to fill voids, encapsulate loose rock and dirt, and build the stability back into the soils. The injection plan was designed and safety equipment put in place to protect crew members on the steep incline. Injections were made in increments as the crew worked across the area, recompacting the soil, filling voids, and improving the stability of the slope. Final injections were made in the area of the hillside where the deck and boardwalk would be reconstructed.
The entire retaining wall area and hillside were stabilized, re-compacted and void filled in less than 5 hours. Bearing capacity of the soil was increased and areas void filled to ensure strength and durability of the slope.
The quick, non-destructive nature of the CST technologies makes an ideal solution for slope stabilization and areas where events such as heavy rain, flooding, and erosion have caused unstable soils. The no-dig repair method allows for very little disruption to landscaping features and families.
The CST processes provide fast results that protect from property loss, minimize costs and provide a safe, and durable repair alternative to costly and disruptive underpinning methods. State-of-the-Art equipment and highly trained technicians easily perform repairs in tight or steep areas where large equipment required for traditional repair methods have a difficult time accessing. Areas are able to be used immediately following completion of injections.