Dynamic renovations of the 175,000-square-foot 1441 L Street office building encompass the addition of two new levels of office space and an occupiable penthouse to the top floor. When completed in late 2018, the 30-year-old structure will be larger by 35,500 square feet.
During design, we were engaged to review available subsurface data and assess the capability of the existing spread footings to support the altered structural loads resulting from the new levels. As construction geared up, we conducted a supplemental geotechnical investigation to evaluate support of the crane pad to be installed at street grade. Due to relatively deep soft and loose fill material, the presence of existing utilities, and non-reinforced below-grade walls, we recommended supporting the pad on auger cast pile foundations.
Renderings courtesy of DEP Designs and ArchiBIM