Reaching substantial completion on National Park Service's seawall reconstruction at West Potomac Park

Enhancing flood protection along the National Mall waterfront

The National Park Service (NPS)’s seawall reconstruction at West Potomac Park and the Tidal Basin in Washington, D.C. has been substantially completed under budget and ahead of schedule. This marks a major milestone for the project, which serves to strengthen and restore the shoreline around some of the nation’s historic and world-famous landscapes, including the Thomas Jefferson Memorial, Franklin Delano Roosevelt Memorial, and the home of D.C.’s annual Cherry Blossom Festival.

Funded by the Great American Outdoors Act, the $113 million rehabilitation project includes three seawall segments: 1,200 linear feet (366 meters) at Tidal Basin East, 820 linear feet (250 meters) at Tidal Basin West, and 4,700 linear feet (1,433 meters) at West Potomac Park. The design covers 6,720 linear feet (2,048 meters) of shoreline upgrades.

Image credit: Cianbro

Image credit: Cianbro

NPS engaged the Cianbro - Mott MacDonald design-build team in 2023 to address critical issues such as tidal flooding, saltwater intrusion, and sea level rise, while preserving the historic character of the more than century-old sea wall and the unique landscape of the site. Leveraging the use of driven plumb piles, a raised relieving platform elevation, and precast concreate pile caps and slabs, the final design incorporated long-term climate resilience and the ability to adapt to rising water levels over time. The design-build approach enabled accelerated delivery by overlapping design and construction phases and incorporating modular components.

“This project is a legacy of our nation’s capital that will be enjoyed by millions of citizens and visitors for generations to come,” said Kris Pagán, principal project manager at Mott MacDonald and structural engineer of record. “These improvements are essential to preserving historic assets and ensuring public safety along the National Mall waterfront.”

Natasha Taylor, project manager at Cianbro added, “I am very proud to be part of the team that restored the seawall around the Tidal Basin and Potomac River for generations of people to enjoy the shoreline and cherry trees.”

Construction for the Tidal Basin began in 2024 and is expected to be fully completed in April. The West Potomac Park construction is scheduled to be completed later this year. The enhanced seawall design increases flood protection, improves visitor safety, reduces erosion, and allows for future height adjustments to accommodate projected climate change impacts.