SNOWMASS CANYON STATE HIGHWAY 82 PROJECT

Yeh and Associates has been involved with evaluation, analysis and design for improvement of 3.5 miles of Snowmass Canyon - State Highway 82, near Aspen Colorado. This section of highway is located in a complex geologic area with slopes in excess of 500. Yeh and Associates role on the project was to provide a geologic / geotechnical investigation, slope stability evaluation, and retaining wall design.

The geologic and geotechnical investigation utilized helicopter transported drilling rigs. The subsurface conditions were evaluated by drilling 289 borings with this equipment. Refraction seismic surveys were used to estimate bedrock depths between boreholes for design and constructibility. Ground anchor, caisson, and micropile testing was also conducted on the project to determine appropriate design parameters for these structures. Geologic hazards that were identified on the project included landslides, rockfall, debris flows, and collapsible soils. The competency of some of the bedrock in the area was affected by faulting.

The roadway alignment was designed with both cut and fill retaining walls. The retaining walls for the project consisted of soil nail walls, mechanically stabilized earth (MSE) walls, ground anchor / tieback walls, and micropile foundation walls. Because of the steep terrain, MSE wall sections were over 40 feet in height and ground anchor and soil nail wall sections were over 25 feet in height. Inclinometers, borehole extensometers, tape extensometers, and survey points were installed to monitor earth movements and wall settlements.

The contract bid documents included a Geotechnical Data Report and a Geotechnical Baseline Report. These documents were provided with the standard plan sheets as an effort to convey geological and geotechnical information relevant to bidding the work. These types of documents have been shown to produce more accurate bids as well as limiting differing site condition disputes on large projects, where geological conditions have a significant impact on the work.