Repairs to the Washington Monument will require massive scaffolding to be built around the 555-foot obelisk and may keep it closed until 2014 after it was damaged by an earthquake last year.
National Park Service spokeswoman Carol Johnson said Monday that a damage assessment found scaffolding is necessary to provide workers access to the top of the monument.
Engineers determined most of the damage is above 475 feet on the structure.
The park service has put the $15million project up for bid, with proposals due by July 31.
Back to the past: In 1999 (left), the Washington Monument underwent refurbishment and will have a similar scaffolding structure now that repairs must be made (right)
Ms Johnson says the agency hopes to award a contract and begin mobilizing in September, and it will then take 12 to 18 months to complete the repairs.
The monument was the world’s tallest man-made structure when it was completed in 1884, but no longer.
It has been given a great deal of attention ever since the 5.8-magnitude earthquake hit the nation’s capital last year, when the unexpected incident caused a worrying amount of damage to the structure.
Surveyors took measurements of the 555-foot-tall obelisk from several long-established points in the ground known as bench marks where survey work has been done in the past.
The monument sits about 15 to 20 feet above sea level and has sunk about 2 inches into the ground since its completition.
The tricky part is that the monument is on land that was once underwater as most of the National Mall was created with soil dredged from the Potomac River. That’s one reason why the structures on the mall are prone to settling in the ground, leading to problems that required major renovations of the Jefferson Memorial plaza and the Reflecting Pool.
Several large cracks and dozens of smaller ones formed in the top portion of the monument during the earthquake on August 23, and chunks of stone were shaken loose on the exterior and interior of the structure.
Initially, analysts expected the construction to last until August 2013, but today’s estimate shows that they clearly underestimated the project.