Jefferson Memorial Seawall Repair

Restoring a Treasured Monument
[Clark Civil] has shown a firm commitment to technical accuracy and quality of the finalized product...All members of the Clark project management and superintendent team on this project have actively demonstrated excellent and proactive flexibility, cooperativeness, tenacity, and innovativeness in resolving problems. The team has gone above and beyond expectations…
National Park Service
Washington, D.C.
National Park Service
Year Completed: 

Since its dedication in 1943, the Thomas Jefferson Memorial has become one of Washington, D.C.’s most visited landmarks. Seven decades after its debut, settlement at the north seawalls, located in the Tidal Basin, threatened the Memorial’s stability. This project, funded by the American Recovery and Reinvestment Act of 2009, rehabilitated the foundation of the stone-faced seawall without impeding visitor access.

The Thomas Jefferson Memorial Seawall Repair project design consisted of 39, 48-inch-diameter drilled shafts installed to depths of up to 120 feet below work trestle elevation. In order to access the face of the seawall, the project team installed a sheet pile cofferdam and dewatered an area within the Tidal Basin along the length of the seawall. The existing timber piles that were supporting the seawall were abandoned in place, and the structural load was transferred to 39 load bearing cast-in-place concrete caissons. Due to the limited work area on the project site, the caisson rebar cages were partially assembled offsite and shipped to the job for final assembly over drilled caisson holes. 

Simultaneous to the replacement of the seawall, Clark demolished and repaired existing grade beams, or grillage, as necessary, under the plaza area. This portion of the construction required extremely accurate sequencing in order to maintain access to the seawall.

All work occurred on the Memorial's North Plaza. Since the Memorial is open to the public 24 hours a day, Clark developed and maintained a logistics plan that allowed access to the Memorial without detracting from visitors' experience.