The $15 million repair project is so far along that the decorative lights, which have been on nightly since July 8, will be turned off Monday, and the 500 tons of scaffolding will start coming down Nov. 12.
The external repairs are 80 percent finished, and the monument is on track to reopen by spring, the National Park Service said.
“Sunday’s the last night for the lights,” Park Service spokeswoman Carol Bradley Johnson said.
Although the exterior work is almost finished, work on the interior is only about 30 percent complete, she said. And the grounds around the monument have to be re-landscaped.
“We’ve still got a lot of work to do,” she said.
The scaffolding, which started to go up in February and was topped out in May, will come down gradually from top to bottom. It will take about three months to remove.
During a tour on the scaffolding Thursday, 490 feet up the 555-foot monument, Park Service officials and construction superintendents showed what had been done to repair the hallowed edifice.
The trip toward the top was made in an external construction lift, attached to the scaffolding, that ferries workers and equipment up and down the south face of the monument.
As the elevator, which was equipped with a wind meter, crawled upward, it entered a zone on the structure that few people get to experience up close.
The Potomac River, the Lincoln Memorial, the Mall and the U.S. Capitol slowly shrank into miniature.
Helicopters clattered past below, and jets landing at Reagan National Airport seemed at eye level.
The Washington National Cathedral, to the northwest, and the Basilica of the National Shrine of the Immaculate Conception, to the northeast, sat in the haze in the distance.
The moderate weather on the ground gave way to a damp, chilly, southerly wind 490 feet up.
“It’s amazing to work up here every day,” said Steve Monroe, lead project superintendent for Rockville-based Grunley Construction.
“You never get sick of it,” he said. “Not only because of the historic value . . . [but] being at high elevations, being so safe. You get so used to it.”
The marble and granite monument was most severely damaged near the top.
The 5.8-magnitude earthquake that struck the East Coast on Aug. 23, 2011, whipsawed the edifice at the top, shaking stone loose from the surface and opening cracks so wide that light shined through.
In addition, the monument, which was begun in 1848 and finished in 1884, has seen more than a century of rain, snow, sleet and wind.
As a result, the weathered surface of the stone looks like an abstract sculpture in some places.
In other areas, the monument is a patchwork of repairs going back decades.
Much of this can’t be seen from the ground.
The project is “not meant to be an aesthetic repair,” said James M. Perry, the chief of resource management for the mall and memorial parks.
“As you can see, it has lots of patches, lots of dutchmen,” Perry said. “There’s been lots of mortar put here and there over the years. And that’s what the monument looks like. We want to maintain the character and not treat it as an aesthetic work of art.”
“It shows its age very well,” he said.
Officials said 150 dutchman patches were used, and the work crews ran out of spare marble they had on hand for repairs.
But a company was found that had salvaged old marble steps from homes in Baltimore. That marble had come from the same quarry as some of the monument marble.
On Thursday, workers were scrubbing repaired surfaces, smoothing mortar into joints and “sounding” suspect stone with metal tools to check for internal damage.
“An experienced mason can tell by the sound whether there’s a void” that needs to be fixed, Perry said. “It’s a basic masonry repair project. It just happens to be 500 feet in the air and in the middle of the National Mall.”
Normally entered by about 600,000 visitors each year, the monument honors George Washington, Revolutionary War hero and the nation’s first president. It has been closed since the earthquake.
The repair project is being funded by the government and a $7.5 million donation from local businessman and philanthropist David M. Rubenstein.
The monument, one of the tallest free-standing masonry structures in the world, is also perhaps the most recognized of American icons.
“It is an astounding building,” Johnson said.