our work
3220 Prospect Street Condos
The Project
Located in Georgetown, one of Washington, DC’s renowned neighborhoods, this project involved replacing a parking lot with a 115-unit condominium building, featuring a basement level ranging from 10 to 20 feet below the surrounding grades. Bounded by Prospect Street to the north and surrounded by various adjacent properties and structures to the west, south, and east, the site presented unique challenges.
The sheeting and underpinning methods varied based on the diverse conditions around the perimeter. They included drilled soldier beams, lagging, internal steel bracing supported by concrete heel blocks, and hand-dug underpinning. Notably, encountering quartz boulders at the northwest corner necessitated rock drilling and modifications to the sheeting design.
year
2023
Location
3220 Prospect St. NW, Washington, DC
Scope
Sheeting, Underpinning
Category
Multi-Family
General Contractor
Landmark Construction Development LLC
Consultants
Architect: Eric Colbert & Associates
Structural Engineer: Ehlert Bryan
Geotechnical Engineer: MTI Engineering and Testing
Challenges and Results
One of the most significant hurdles, which was uncovered during the initial demolition and site preparation phase, arose from the condition of the adjacent eastern building. Decades of previous construction iterations had left the existing wall in a precarious state. Collaborating closely, Steele Foundation engineers and craftsmen devised an efficient and timely solution to laterally brace the existing building, enabling the safe installation of underpinning and the progression of construction.