DC Mud Threatens Jefferson Memorial

Portions of the Jefferson Memorial, one of the most recognizable sites in Washington, D.C., may be sinking into the mud on which the entire 18 acre site was built. Right now, the distinctive dome is unaffected, but sections of the plaza and ring road are showing signs of settlement.

It's probably not endangering the majestic 32,000-ton domed structure itself, although it's being monitored for movement.

The big problem seems to be a section of the sea wall that is breaking from the memorial's plaza and settling into the Tidal Basin. The "ring road" along the memorial's circumference also seems to be shifting, officials say.

Such movement is an alarming -- and chronic -- problem at the Jefferson Memorial, which was built in the late 1930s and early 1940s atop pilings and caissons sunk into an artificial mud flat that is about 100 feet deep. Engineers have been struggling for decades to keep everything firmed up.

The National Park Service, which oversees the 18-acre memorial site, is trying to see how bad the movement is this time and is wondering what it will take to fix it.

The current problems, at one of the most photogenic monuments in the country, were noticed early last year, said Stephen Lorenzetti, acting superintendent of the National Mall & Memorial Parks.

Since then, the western section of the sea wall, which separates the memorial complex from the Tidal Basin, has dropped in places about six inches below the plaza, which it adjoins.

If the problem is present at the Jefferson Memorial, a closer look at the adjacent FDR memorial might be in order given that it may be subject to similar settling.