Alkali Creek Bridge Replacement

Montezuma County, Colorado
Montezuma County, Colorado

The purpose of this project was to replace the bridge carrying County Road North over Alkali Creek, located approximately 5 miles northwest of Cortez, Colorado, in Montezuma County. The project included demolition of existing structures, roadway improvements, local drainage improvements, channel improvements, and the new bridge structure. The bridge has heavily corroded metal cribbing at the east abutment and northwest and northeast wingwalls and was deemed structurally deficient in 2016.

The hydrology was completed using USGS Streamstats and HEC-HMS since there were no gages, and was made conservative by not accounting for the Narraguinnep Reservoir which is located within the upstream portion of the watershed.

RESPEC performed the bridge hydraulic analyses, minimum freeboard requirements, and scour analysis. The new bridge was designed to not have any adverse impacts to the floodplain, protect against scour, and mitigate channel erosion and stream instability. Construction took place in fall 2022.