The Arris, Parcel N at The Yards

SK&A provided structural engineering services for this 11-story, 325-unit, multifamily residential apartment building. Located on a former part of the Navy Yard, the project included approximately 20,000 sf of retail space as well as two courtyards, a rooftop pool, and a small green roof.  The building sits atop a three-level, 110,000 sf below-grade structured parking garage for 250 cars and has a landscaped plaza on the garage roof slab at grade level.

At the northern end of the building, two existing sewer lines cross the site. Located just below the B1 level, the first of the two sewer lines is a 6-foot diameter, 100-year old masonry sewer that crosses the entirety of the east-west footprint.  The sewer had to remain active during construction and the ability to access this line in the future was mandated by the utility. Drilled shaft foundations were used to support the building on either side of the line, circumventing the sewer and maintaining the required clear distances.  A structured slab-on-grade was used above the line, spanning to the adjacent drilled shafts while imposing no additional loads on the sewer from occupancy use.  Additionally, this slab was designed to allow for a 10-foot section to be removed for future maintenance of the line while the larger area of slab continued to provide support for the primary building structure.