Downtown Redevelopment with Complex Site Constraints: Fid-Bau Portal

Downtown Redevelopment with Complex Site Constraints

Niehoff, James W.

When a developer selected a site in Denver for a new office building, there were numerous challenges to be faced. Due to zoning and height restrictions, the 8 story building required 4 levels of below grade parking, extending over 6 meters (20 feet) below the water table in coarse sand. On the northwest and southwest sides of the site, an existing basement wall was present at the property line, supporting critical utilities in the backfill zone. On the northeast side of the site, a portion of a newly completed building was supported on shallow footing foundations located about 6 meters (20 feet) above final proposed grade at the property line. As the new building was to extend to the property line, there was no room for a temporary excavation bracing system. All of these factors dictated a creative approach to site preparation and building construction. The ultimate approach to construction involved the installation of a secant wall around the entire periphery of the site, extending into bedrock to cut off the majority of the groundwater, provide lateral and vertical support for the adjoining building, protect adjoining utilities and serve as the final basement wall for the office building.