Much of the existing area was covered by the previous building’s concrete slab, which was removed – along with old foundations – prior to stone column installation. Underlying the slab was between 5 ft and 10 ft of loose, mostly sandy fill. Stiff to hard natural clays were beneath the fills. Groundwater was often perched within the near-surface fill.
Drilled piers were originally considered for the foundation system, but due to the variable bearing layer and cost of installation, they were eschewed for stone columns. The elements were installed through the fill soils and designed to provide 3,000 psf of bearing capacity while limiting settlement to 1 in. Slabs were constructed on-grade following a proof-roll. Menard installed 600 stone columns to depths of up to 15.5 ft, and performed two load tests to confirm the stone column modulus assumed during the design phase. Frequent and severe rain events caused delays, but Menard worked with General Contractor Brinkmann Constructors to work in dry areas of the site to maintain schedule. The rain also meant that more areas showed the perched groundwater, prompting Menard to switch from a top-feed installation to a bottom-feed installation to properly construct the stone columns in the wet conditions.
For an expansive, speculative bulk warehouse project in Pontiac, MI, Menard installed 600 stone columns to support a 711,000 sq-ft warehouse.