Children’s Hospital Ambulatory Surgical Center
Seattle Children’s Hospital
Hart Crowser assessed geotechnical site considerations for several potential sites and provided geotechnical engineering design recommendations for the selected site in Bellevue. The development included a three-level medical office building and underground parking, and a three-level parking structure partly below grade. Slopes on the site (mapped as a “steep slope” critical area by the City of Bellevue) required attention to access road grades and the bottom of foundation elevations. The site had previously been regraded with varying thicknesses of fill soils. Wetland areas occupy the site boundary.
A 30-foot-high permanent soil nail shoring system was selected to provide economical shoring so that the building’s moment frame does not have to resist permanent static or seismic earth loads. Mechanically stabilized earth (MSE) was used above one of the permanent shoring walls to attain final grades. Foundation support recommendations incorporated flexibility to account for varying thickness of fill in the regraded areas. Careful earthwork methods and construction staging were used to balance cut and fill soil volumes (for moisture-sensitive soils) to maximize reuse of on-site soil to save costs and address construction site access constraints.