Stabilizing the Limekiln Creek Cribwall in Big Sur

The Challenge

Voids throughout a 160′ portion of crib wall.

Limekiln Creek State Park is a favorite stop for tourists visiting Big Sur. It boasts a waterfall, an excellent trail with giant redwoods, and camping. Visitors are provided access via the US-1 Limekiln Creek Bridge. The northern bridge abutment is protected by the Limekiln Creek crib wall, which was under duress. A crib wall is a retaining wall structure designed to provide structural support. In Limekiln Creek’s case, it was used for the slope along the abutment against tidal fluctuations and storm surge. Over time, the crib wall had begun to lose its fill soil due to water infiltration and erosion. Large voids formed within the wall, and the soil loss led to failure at parts of it. This is when Caltrans contacted Groundworks to see if they could fill the voids and stabilize the soils.

Key Facts

The Solution

NCFI Strata-Fill™ 24-023 low-exotherm polyurethane system was used to fill the voids.

The crib wall was about 290 linear feet with voids throughout a 160-ft portion. The goal was to use the NCFI Strata-Fill™ 24-023 low-exotherm polyurethane system to fill the voids, stabilize the wall, and densify the loose soils. The 24-023 was injected into the wall through 1/2” steel rods. Those rods were then inserted through 5/8″ holes that were drilled through the surface. When large volumes of geotechnical polyurethane are being used, the polyurethane’s exothermic reaction results in high temperatures that can lead to fires or unsafe conditions. This is why Groundworks used the Strata-Fill™ 24-023. The low-exotherm system is designed to be applied in large volumes without overheating, while serving as a light-weight fill material. 

The Impact

Wall stabilized in one and a half days.

Groundworks filled the voids and stabilized the 160ft section of the wall in 1 1/2 days. The project was completed just in time, as the proceeding months resulted in torrential rainfall throughout California and the wall could have been compromised. Caltrans was completely satisfied with the project and the Limekiln Creek Crib Wall’s useful life was significantly extended due to an innovative approach.