Pioneer performed a comprehensive geotechnical investigation for the proposed redevelopment consisting of a series of 2- to 4-story masonry/frame structures with concrete slab-on-grade floors and mid-rise 4- to 5-story multifamily residential buildings.
The site generally consisted of approximately 8 to 15 feet of miscellaneous urban fill, overlying very tough to soft silty clay deposits. These urban fill materials were considered to be contaminated for purposes of disposal.
Through a series of soil borings and test pit excavations, Pioneer determined that the fill materials were relatively compact and free of void spaces and organic materials. Subsequent calculations verified that a low bearing capacity of 500-1,000 psf with acceptable differential settlements could be achieved for these urban fill materials. Therefore, in order to minimize removal of the existing, contaminated materials and avoid deep, costly replacements, Pioneer recommended shallow foundation systems consisting of reinforced concrete mat slabs for the low-rise buildings and pipe-pile deep foundation systems for the mid-rise buildings.
Pioneer subsequently provided the on-site field monitoring for the construction of the mat slab foundations and pile installations at the site.