Client: LR Development Company, LLC / Heartland Housing, Inc. | Location: Chicago, IL
Starting in 2005, Pioneer was contracted to perform a geotechnical investigation for an extensive development composed of numerous two to five-story mixed-use buildings, as well as a one-story, slab-on-grade building. Pioneer performed a total of three separate investigations to fulfill the challenging foundation design necessities for the proposed complex.
The subsurface investigation revealed challenging subsurface conditions, including up to 12 feet of typical Chicago urban fill containing demolition debris from previous site usage, causing difficult drilling conditions over a thin layer of Chicago very tough silty clay crust. The crust was underlain by a deposit of very soft Chicago “blue clay”, transitioning to very tough to hard silty clay soils beyond a depth of 45 feet below surface grade. The hard clay was underlain by dense silt that extended to the top of bedrock elevation at 80 feet below the existing grade. Vane shear testing was also performed throughout the very soft “blue clay” soils for assistance in design parameters.
Due to the deep, unsuitable urban fill materials, Pioneer determined that conventional foundations employing a remove and replace method in order to attain adequate support for the building loads was not economically feasible. Based on the comprehensive analysis of the subsurface investigations, Pioneer provided the Client with alternate foundation type options in consideration of feasibility and budget. Foundation design recommendations included shallow mat foundations for smaller structures and deep foundations systems, such as H-piles, steel pipes, and aggregate pier foundations, for the heavier-loaded buildings.
