The Potomac Interceptor serves as a critical wastewater lifeline for multiple jurisdictions across the Washington, D.C. metropolitan region. When inspections revealed that Manhole 31 and the surrounding 78-inch reinforced concrete pipeline had begun to deteriorate, DC Water made the proactive decision to address the risk before failure occurred – selecting the Ulliman Schutte Construction and Brown and Caldwell design-build team through a qualifications-based, progressive design-build process. Rather than waiting for a crisis, DC Water invested early in a collaborative delivery approach that gave the team the flexibility to adapt as conditions became clearer.

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That flexibility proved essential. During Phase 1, the team discovered that conditions differed significantly from record drawing. Working side by side through weekly design workshops, the Client, Architect, design-build team, and specialty contractors developed an innovative response. One standout outcome was an innovative slip-lining approach that stabilized the interceptor under active flows – eliminating the need for continuous bypass pumping and protecting the Potomac River from overflow risk. That same collaborative process guided value engineering of the energy dissipator layout, selection of the construction method, and use of advanced technologies, including Electrical Resistivity Imaging and computational fluid dynamics modeling to reduce uncertainty and inform construction sequencing.

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The result is a resilient, long-life asset built with corrosion-resistant materials, a 98-MGD vortex flow energy dissipator, and protective systems designed to extend service life and reduce future maintenance. Throughout construction, the team maintained uninterrupted sewer service, kept the Potomac Heritage National Scenic Trail open through temporary realignment, and incorporated community feedback into decisions on work hours, equipment, and site restoration. The project earned an Envision Silver award from the Institute for Sustainable Infrastructure, reflecting the strength of a delivery approach where shared accountability, early risk resolution, and proactive investment came together to protect critical public infrastructure.

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