Development in the mountain towns of Colorado has often required engineers and geologists to address issues with problematic soils and potential slope instability. The Maryland Creek Ranch development constructed north of Silverthorne, Colorado included 240 units constructed on a relic landslide complex.
Design for the site required the investigation of the relic landslide complex through review of mapped relic landslide features and site reconnaissance by a number of geologists and engineers. Over 50 geotechnical borings were drilled and 10 test pits were excavated at the site to investigate the landslide features and collect soil samples. Inclinometers and piezometers were installed more than 10 years prior to development of the site to monitor slope movement and groundwater fluctuation. Inclinometer and piezometer data were used to guide additional geotechnical investigations and the design of stabilization measures. Site constraints and considerations for design were relic landslides, slump features, steep slopes, and shallow groundwater.The design of stabilization features for the infrastructure included the installation of 4,500 feet of horizontal drains, 13,000 feet of underdrains, and 45,000 square feet of soil nail, ground anchor, and Hilfiker wall systems. The piezometers and inclinometers will continue to be monitored after construction.
