Beartooth Highway – Quad Creek Debris Flow Mitigation

DOWL was retained by the Montana Department of Transportation for emergency repairs due to a landslide and associated debris flow which occurred during heavy rainfall. The debris flow in Quad Creek plugged a large concrete box culvert and jeopardized the Beartooth Highway, an All-American Road providing access to Yellowstone National Park. The unique characteristics of this high mountain drainage, with an extremely high gradient, unstable slopes, and extreme sediment loads required an innovative solution allowing for control of pulse-flows of gravel and cobble sediments as well as typical snowmelt runoff.

DOWL designed an innovative rack installed on the inlet to pass typical bed load sediments while preventing large debris flows from plugging the culvert. This was done by allowing water to continue to pass through the rack, flushing cobble and sediment through the culvert. DOWL also designed slope stabilization countermeasures to protect the downstream embankment which was eroded by heavy flows through the adjacent overflow culvert.