The challenge:  The work was to be done while the building was operational, closing parts of the building was possible, but had to be scheduled and additional downtime was not an option. The space was limited since we had to advance tubes 12’ below grade with a limited ceiling height. The soils were cohesive in nature and appeared to be softer in some areas of the building. The doors aligned North to South were showing signs of differential settlement. The solution was to make injections for soil improvements between 4-12 feet below the existing grade in 3 separate lifts and in a pre-determined grid pattern. We increased the load bearing capacity of the sub grade, achieved a level of elevation change to ensure the load was placed on the sub grade, and improvements were immediate.