Yeh provided geotechnical and geologic information regarding site conditions of the Crater Trail, damage due to severe erosion in areas, for repairs and reroute.

The Sperry Chalet was built by the Great Northern Railroad in 1913 and severely damaged in a fire in 2017. The reconstruction and restoration retained as much of the historic structure as possible. Yeh staff accessed the site on horseback, evaluated site conditions, and developed recommendations for allowable bearing capacity for new foundations.

Yeh performed geotechnical engineering work including field reconnaissance, wall assessments, wall evaluation, construction observation, and documentation of tieback repairs.

Yeh provided geotechnical design, construction inspection, soil and concrete testing services for MSE retaining structures, drilled shaft bridge foundations for 3 bridges, trail subbase soils, trail concrete, temporary shoring soil nails, rockfall mitigation, and a unique underpass structure which carries the trail under US Highway 6.

Yeh provided geotechnical services including complete tunnel geotechnical investigation and generation of the Geotechnical Data Report (GDR) supporting underground design for expansion of both the East- and Westbound tunnels. Yeh performed portal rockslope design and rockfall protection design for the east- and westbound tunnels. Additionally, Yeh performed deformation monitoring of both I-70 tunnels during widening construction.

Yeh staff provided landslide remediation including expanded polystyrene (EPS) and tiebacks.

Design and remediate a landslide and incorporate the repair reconstruction of a modular block retaining wall.

Yeh geotechnical engineering staff characterized subsurface sandstone, evaluated rock rippability, and designed rock cuts, rockeries, and pavements. Yeh then provided inspection and materials testing during construction.