A 61 m section of the east bound lane and side slope of US Highway 160 between Mesa Verde National Park and the town of Durango failed in the Spring of 1987 (Yeh and Gilmore 1989). The failed road section consisted of 1.5 m of till and shaley clay embankment constructed on 1 to 4 m of clay overlying shale. The embankment alignment intercepts surface runoff along a valley slope. The total volume of material involved in the failure is about 8,400 m³. The cause of sliding is attributed to be increased driving mass due to a rising water table. There has been a history of similar failures at other locations along the highway alignment. Restoration measures for such previous failures included removal of slide debris and replacement with borrow or sawdust, support of the failed section with piles or tieback wall. Two larger but stable slide remnants were identified in the problem area. Considering the possibility of initiating a much larger slope movement; conventional remedial alternatives as well as partial removal of the slide debris and replacement with geofoam were reviewed. The geofoam option was selected. About 550 m³ of EPS geofoam was used for reconstruction of the failed roadway and side slope in a period of 6 weeks. Costs for the conventional alternatives were estimated to be on the order of 1 million dollars. The cost of the completed geofoam option in 1989 was $160,000. Post construction observations indicate the slope and roadway performance has been satisfactory.

References

Yeh, S-T., and Gilmore, J.B., (1989). "Application of EPS for Slide Correction Stability and Performance of Slopes and Embankments II." ASCE Geotechnical Special Publication, No.31, pp. 1444-1456.