GEOLOGIC HAZARDS AND GEOLOGIC CONSTRAINTS, I – 70 CORRIDOR PROGRAMMATIC ENVIRONMENTAL IMPACT STUDY, COLORADO

The recent rise in Colorado’s population has led to detailed studies for options to increase the transportation capacity along the I-70 corridor. This corridor is the primary access route through the mountains of Colorado for trucking industries as well as recreation and tourist activities. Yeh and Associates was responsible for performing the geotechnical, geological, and hazardous materials evaluation of the programmatic environmental impact study of the I-70 corridor from Denver to Glenwood Springs, Colorado. This project involved identifying and describing the geologic and soil conditions along the corridor and the potential hazards and engineering constraints posed to the present and proposed transportation system by these conditions.

The geologic hazards identified include; rock fall, debris flows, landslides, avalanches, collapsible and swelling soils, and the hazards related to historic mining activity such as heavy metals in mill tailings and mine subsidence. The study area varied but generally encompassed the I-70 corridor and the ground to the ridgelines on either side. Through research of existing maps, aerial photos, and site-specific studies, a geologic hazards inventory map was produced.

The second phase involved observation of each geologic condition that affects the existing I-70 corridor. Preliminary field verification was conducted to verify the hazards and their impacts on current and proposed alignments. Evaluation included the history (cause, origin) and the current condition (size, materials, stability) of the hazard as well as any mitigation procedures previously performed. From the information obtained, an assessment method was developed to quantify the potential impacts the existing geologic hazards and geologic constraints may have on the proposed transportation alternatives.