According to Schnabel Engineering:
In 2005, settlement and lateral movement of the North Plaza and the Ashlar Seawall prompted the National Park Service (NPS) to close a portion of the Jefferson Memorial due to public safety concerns. Schnabel was commissioned by NPS to analyze the problem and develop a repair strategy. [They] 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.
Schnabel conducted a value analysis with NPS to determine the best remedy. The selected option 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 Washington, DC 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.
In 2016, I filed a FOIA request to see documentation relating to the project. Below, you will find a breakdown of the records that came in from the National Park Service (NPS).
FOIA Response, dated November 10, 2016 [3 Pages, 0.4MB]
JEFM_808_106595_0440pg.pdf – CONTRACT #1443C2000040800 REPAIR AND CONTROL SETTLEMENT AT JEFFERSON MEMORIAL SEAWALL, NORTH PLAZA AND TRANSITION AREAS – PMIS NO 128232 – SUPPLEMENTAL DOCUMENTS [441 Pages, 25.5MB]
JEFM_808_128922_A.pdf – PROJECT SITE [3 Pages, 10.4MB]
NAMA_802_D69_0001_of_0072_F808C6.pdf – CONTRACT #1443C2000040800 REPAIR AND CONTROL SETTLEMENT AT JEFFERSON MEMORIAL SEAWALL, NORTH PLAZA AND TRANSITION AREAS – PMIS NO 128232 – FINAL PREDESIGN DOCUMENTS [72 Pages, 13.4MB]