Keller addressed highly variable subsurface conditions by tailoring each earth support method, providing the client with the most cost-effective solution while meeting schedule milestones.
The Saint Louis University Hospital’s $500 million campus renewal program, slated for completion in 2020, includes a new 800,000 sq ft hospital facility and outpatient care center, expanded parking, green space, and areas designated for future office expansion.
Two temporary earth retention systems, each 250 ft in length, were required at different sections along the perimeter of the overall excavation footprint to protect adjacent active roadways. Each section varied in terms of excavation depths, soil conditions, and rock elevations, requiring a location-specific approach to the earth retention technique selected.
In the section with deeper rock elevations, Keller designed and installed a drilled and rock-socketed soldier pile and timber lagging system to retain the maximum 21-ft excavation from existing street grade. For the second section, where rock elevations extended well above the bottom of the excavation, a soil/rock nail retention system with shotcrete facing was installed for the maximum 27-ft excavation.