Cianbro Wins $113M Contract for Nation's Capital Seawall Rehab

Water now flows over parts of the seawall along the Potomac River twice daily under normal tide conditions.
*Photo courtesy of National Park Service*

The National Park Service selected The Cianbro Cos. of Maine for a project to rehabilitate failing seawalls along the Potomac River and Tidal Basin in the nation's capital. The $112.8-million design-build contract is part of nearly $500 million in infrastructure improvements the agency has planned around the National Mall ahead of the 250th anniversary of U.S. independence in 2026.

The walls by West Potomac Park in Washington, D.C. date to the late 1800s and early 1900s. A combination of age, rising water levels and poor drainage has caused portions of them to settle by as much as 5 ft, according to the Park Service. Water now flows over portions of the walls twice daily under normal tide conditions, threatening visitors’ safety, as well as the cherry trees. Some 1.5 million visitors visit the Tidal Basin annually.

Jeff Rienbold, service superintendent of the National Mall and Memorial Parks for the Park Service, said in a statement that repairing the walls “has been a top priority.” The work is aimed at extending the structure's life expectancy by about 100 years.

The project would involve removing and reconstructing about 6,800 linear ft of the wall reusing salvaged stones from the historic wall when possible, according to the Park Service. The contractor would construct pile-supported foundations to prevent settling and allow for future height extensions as needed to meet sea level rise and storm surge. The plans also include widening walkways around the tidal basin and regrading landscaping to improve drainage.

Work is planned to start midway through next year.

Pittsfield, Maine-based Cianbro ranks at No. 96 on the ENR Top 400 Contractors list and is ENR New England’s 2023 Contractor of the Year. A representative from the company was not immediately available to comment on the project.

The Park Service is paying for the project from the National Parks and Public Land Legacy Restoration Fund. The Great American Outdoors Act of 2020 provides the fund with up to $1.3 billion per year through 2025 for projects to enhance national parks.

Other National Mall projects planned ahead of the 2026 event include construction of a $69-million visitor center near the Lincoln Memorial and renovation of Constitution Gardens.

James Leggate is an government news correspondent at ENR. He has reported on a variety of issues for more than 10 years and his work has contributed to several regional Associated Press Media Editors and Murrow award wins.