In 2005, settlement and lateral movement of the Jefferson Memorial’s north plaza and ashlar seawall prompted the National Park Service (NPS) to close a portion of the popular tourist site due to public safety concerns. Schnabel was commissioned by NPS to analyze the problem and develop a repair strategy. We conducted an extended settlement study to determine the cause of the seawall and north plaza movements and the rate of settlement. The problem was in large part due to the foundation timber piles of the seawall not extending to bedrock.
To determine the best option for remediation, we did a value analysis with NPS. The solution involved demolition and then reconstruction of the seawall on 48-inch-diameter caissons and 18-inch-diameter steel pipe piles. This $13.5 million project was one of the first in the District to be funded by the American Recovery and Reinvestment Act of 2009. The project received an ASCE 2012 Project of the Year Award from the National Capital Section.