Hanson-Wilson was selected to expand a BNSF taconite transloading facility. The construction included an enlarged storage area for taconite ore and an underground rail car unloading station; construction of dock bins and anchor bulkhead sheeting on Lake Superior that would enable ore transfer to shipping barges; and a connecting conveyor system and associated structures. HWI conducted a study of the subsoil conditions at the new yard, and stability studies for proposed taconite piles.

Two methods were used to evaluate the support capacity of the highly plastic, clay subsoils. In the first method, statistical studies of standard soil test data were conducted. This data was compared with data on existing yards where past failures had occurred. In the second method, field vane shear tests were conducted, and correction factors applied that were related to the plasticity of the soil. A limit was set on the safe height of taconite piles.

Criteria for the underground unloading station included recommendations for braced cuts, sloped cuts, allowable foundation pressures, lateral design pressures on walls and hydrostatic uplift. H-pile supports were recommended for the heavy dock bins, and wave equation analyses and pile load tests were conducted to verify the recommended 100-ton design capacity. HWI made recommendations for the foundation of the various conveyor system structures, which included wood piles, drilled piers, spread footings and mats. We provided additional consultation during the construction phase and made several site visits to check construction progress.