K+A was retained by DMJM to complete geotechnical engineering and engineering geology studies for widening about 3.3 miles of State Highway 119 immediately northwest of Black Hawk, Colorado. Work included developing design recommendations for 11 inboard rock cuts ranging from 150 to 800 feet long and up to 60 feet high, as well as rockfall catchment ditches, new asphalt pavement and pavement overlays, and rockfill embankments. Given the highly variable rock conditions restrictions limiting control blasting to cushion blasting, and the large number of thin (sliver cuts) planned along the alignment, K+A's involvement in both the design and construction phases of the project was critical to achieving stable rock slopes.

Comprehensive geologic mapping was performed prior to and after the rock excavations to characterize the rock outcrops and cuts with respect to strength, weathering, orientation of foliation, discontinuity features, as well as to identify active or potential seeps, mining adits or other features that could impact the stability of the rock cut-slopes. Specifications and design details for rock excavations and rock reinforcements, required for about 15 percent of the rock cut areas, were developed. K+A also provided rapid service on an as-needed basis to rock excavations, modify cut slope ratios, mark spot bolting locations for portions of completed cuts, and observed and evaluated performance tests for rock reinforcement.

K+A demonstrated flexibility in adapting field designs and alignments to local geologic conditions rather than the other way around. In one sliver cut, K+A convinced CDOT that modifying the roadway alignment slightly was preferable to excavating a sliver cut that could potentially destabilize the hillside and potentially require significant rock reinforcement. Field design for two rock buttresses were developed; one to control rockfall near the top of one cut, and another to stabilize an overhang caused by overblast. Rock netting was recommended, designed and constructed to control rockfall for one 60-foot high cut.