They studied every block — each of which is numbered — for damage from the Aug. 23 earthquake that rattled the East Coast. On Wednesday morning, they finished the examination.
Initial diagnosis: substantial cracks here and there, with minor displaced stone. Overall, the usual aches and pains of a 127-year-old who has just come through an earthquake.
“She’s kind of an old lady,” said Jennifer Talken-Spaulding, chief of resource management with the National Mall and Memorial Parks. “But she’s doing great.”
Now, the National Park Service must decide on a course of treatment to get the hallowed structure reopened. The monument, while solid overall, has been closed indefinitely since the 5.8 magnitude earthquake.
And although the park service says a full picture of the monument’s ills probably won’t be known until next month, some clues have emerged.
Most of the earthquake damage happened near the top of the monument, in the area of the pointed “pyramidion,” said Daniel J. Lemieux, an architect with Wiss, Janney, Elstner Associates, which conducted the exterior inspection.
Because of the 555-foot height and the tapering of the structure, that’s the part of the monument that shook the most. A security camera captured the violent movement of that area during the quake.
The lower section of the monument mostly suffered the loss of weatherizing mortar and patching that shook loose, the National Park Service has said.
The monument, which was constructed from 1848 to 1884, is built of free-standing masonry, meaning there is no cement holding the blocks together.
A few spalls, or fragments, had to be removed, one of which weighed 30 pounds.
Perhaps the most visible damage was a big crack in stone “w538.2”
The so-called “west crack” was spotted by a helicopter right after the earthquake, Talken-Spaulding said.
It appears on the west side of the monument, three “courses” of stone up from the blinking lights near the top.
That crack, and others, have caused some small displacement of stone, she said.
Lemieux said the inspectors, who had been using mountain-climbing gear to access the exterior, finished going over the monument’s south and east sides Tuesday, and the north and west sides Wednesday.
“We found several corner cracks and surface spalls at or near the top of the monument,” he said. “Classic shear-cracking . . . the kind of cracking we would expect to find with the movement that probably occurred up there during the earthquake. The fracture planes on the stone are very clean, which also suggests that they occurred recently and are likely the result of the earthquake.
“The damage as you come down the monument is generally less severe,” he said. “We’re seeing fewer cracks and spalls of any significance as you come down the monument, but still more loss of joint mortar, and some loss of the patching material that may be associated with the earthquake, but is more likely the result of normal weathering.”
The inspectors removed the spalls, which had the potential to loosen and fall. The spalls ranged in size from the 30-pound piece, to others that weighed about 10 pounds or less.
The sounding of the stone with the mallets helps identify spalls.
There are several ways the gouges left behind can be repaired. One is the installation of what is called a “dutchman,” essentially a patch made of matching stone that is fastened in place with cement or pins.
There are numerous “dutchmen” already on the monument from previous repairs, Talken-Spaulding said, and on monuments and memorials throughout the park.
She said she did not think any of the monument stones would need to be replaced, but she was not certain.
The inspectors will “have to tell us,” she said. “That’s why they’re out there.”
“You don’t want to take the whole stone out,” she said. “That’s never what we want to do. . . . If we have to replace anything we’re going to do it with the same material, or a compatible material, so that it weathers the same, it breathes the same, it moves the same.”
Talken-Spaulding said a rehabilitation and study of the monument finished in 1999 showed that there was a small imperfection that was repaired on w538.2 back then. “But there was no crack,” she said.
She said the 1999 study was valuable, and had been used by the current inspectors for comparison, but it is 12 years old.
“We will find things on that building that probably happened in the past 12 years,” she said. The trick is to identify which damage is old, and which stemmed from the earthquake.
“It’s really remarkable that there was that much movement” from the quake, she said, and that the sturdy old lady still is in such good shape.