Faced with a 300-foot-long sinkhole on U.S. 36 between Denver and Boulder, the Colorado Department of Transportation decided to use Geofoam blocks to rebuild the highway’s sunken foundation.
Cracks began forming on the five-year-old roadway in July, and within a week, the retaining wall for the road collapsed and wet clay soil underneath the road caved in. Three months later, the highway lanes were reopened.
CDOT hired Kraemer North America as the contractor for the $20.4 million emergency project. The project involved placing 6,100 blocks of Insulfoam Geofoam EPS22 polystyrene geo-synthetic fill.
The project began with removing the collapsed wall from the top down and then removing 4 feet of dirt below the wall to be replaced. The Geofoam blocks were then placed.
A concrete load-distribution slab was placed above the Geofoam, then came a layer of crushed stone followed by concrete pavement.
