Innovative Solutions for Historic Sewer Infrastructure: The Rehabilitation of DC Water’s Northwest Boundary Trunk Sewer

DC Water's Northwest Boundary Trunk Sewer, a critical infrastructure component, was originally constructed in the 1800s, consisting of three courses of brick above the springline and a cobblestone invert below the springline. The sewer, located not far from Dupont Circle and Embassy Row, features a wye section where the 102″ × 105″ sewer merges with two other effluent pipes. During a scheduled 2023 inspection, missing bricks were observed in the crown of this junction and were planned for repair. Upon reinspection in July 2024, substantial further deterioration was found, and DC Water immediately shut down the roadway and engaged a team of contractors to provide subject matter expertise and rehabilitation of the sewer and void. After visual inspection and thorough analysis, several key project challenges were identified, including high live flow conditions, humidity inside the pipe, adjacent structures and utilities, and odd geometries and design requirements. The project team worked together to implement a rapid turnkey design-build solution. This paper will detail the project challenges faced, the rehabilitation options evaluated, and the implementation process from discovery to completion, showcasing a successful collaboration in a high-profile area.