Demolition is now complete at the future site of the St. Elmo Apartments at 4930 Fairmont Avenue in downtown Bethesda. Heavy equipment is grading the site ahead of excavation of the four-level underground parking garage, and a crane was brought in to lift what appeared to be a large section of pipe. There's also some interesting work going on at the western property line with the building next door. Signage on the perimeter fence indicates that the project being developed by Duball, LLC, Lenkin Co. and Daiwa House has received funding from Bethesda-based EagleBank.
The “interesting” construction is called underpinning. When new excavations are adjacent to existing buildings that have shallower foundations, the existing footings need to be pinned to the soil below the building, so they can still bear the weight of the existing structure. You can see these as diagonal cables extending out from the foundations, where holes are drilled under the existing building, then reinforced with steel pins, and pumped with concrete.
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