The Thomas Jefferson Memorial opened in 1943, but the effort to clean and restore it is using some 21st-century technology.
August 22, 2019, 7:06 PM
The Thomas Jefferson Memorial is undergoing a major restoration project to address clogged drains, leaky roofs, crumbling stone and a peculiar growth that’s discoloring its magnificent white marble. And the effort to clean the 1943 memorial includes lasers.
“This is called a biofilm,” National Mall and Memorial Parks historical architect Audrey Tepper said, gesturing at dark splotches on the memorial’s dome. “It’s a microbial colony of fungi, algae and bacterial growth.”
The lasers clean the marble without damaging it by essentially vaporizing the growth.
“This type of laser we’re using — the 1064-nanometer wavelength — it’s really good at targeting dark soiling,” said Lindy Gulick, architectural conservator for the National Mall and Memorial Parks. “These dark particles are excited by the energy, and they … evaporate from the surface.”
The laser is being tested in small areas before it’s used to clean the entire dome. Broad swaths of white marble are now evident in places where larger laser tests were conducted in 2017.
Scientists worldwide are studying biofilm to try to learn what fuels its growth and what might inhibit it from regrowing once it’s removed.
Lower-tech restoration efforts on the monument present their own logistical challenges.
A mechanical lift and maze of metal scaffolding stairways are used to move equipment, materials and workers more than 100 feet into the air to the memorial’s various levels that need attention. Water and electricity used for restoration work has to be delivered to elevated areas.
Some of the capitals of the memorial’s ionic columns are awkward to access, and have experienced stone failure in the past. They’ve been anchored into place with wires that now need to be tightened.
The panels that create the front triangle-shaped portico roof weigh between 700 and 1,200 pounds each. They’ll eventually be removed, taken to the ground, restored and replaced after the flat surface underneath has been upgraded and waterproofed.
“It’s a dance of all these different things we need to accomplish for this project,” Tepper said.
The 15-month project is expected to conclude in May 2020.
While work is underway, the monument’s inner chamber will remain open so you can see Thomas Jefferson’s statue; the elevator is running; the bathrooms are open; and the gift shop will operate as usual.
Tepper acknowledged the importance of what’s being accomplished.
“There are a lot of challenges here. But, it’s very exciting and I think people will really appreciate seeing the memorial back looking like it was intended to look when it was first designed.”
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