Foundation Challenges and Innovative Solutions: The Wharf Phase 2, Washington, DC-Video

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The presentation examined geotechnical challenges during Phase II of The Wharf, a five-building development on Washington, D.C.’s Southwest waterfront. Construction took place beside shallow, flexible Metro tunnels, a large historic sewer, and variable river-deposited soils, requiring carefully coordinated excavation and foundation designs.<br /><br />To limit tunnel movement during excavation, the team used staged dewatering and a heavily braced support-of-excavation system. Near the tunnels, an innovative wall combined drill displacement piles with conventional auger-cast piles. Monitoring during installation revealed that displacement piles alone caused too much movement, so the team adjusted the mix and installation sequence in response to real-time measurements.<br /><br />Buildings above the tunnels were supported by a mat foundation and load-sharing elements designed to manage concentrated building loads without overloading the tunnels. Elsewhere, rigid inclusions improved weak soils beneath a parking garage. Construction required changes to drilling methods, close coordination among contractors, and continuous monitoring.<br /><br />The speakers emphasized that the project’s success depended on collaboration among the owner, designers, contractors, construction manager, and Metro’s engineering team. Despite unusual conditions and construction challenges, the systems performed within required movement limits.

Keywords

geotechnical engineering

Phase II construction

Washington D.C. waterfront

Metro tunnel protection

support-of-excavation

drill displacement piles

mat foundation

rigid inclusions

construction monitoring