The Washington Monument will soon be swaddled in scaffolding as part of the expected $15 million effort to repair damage from last summer’s 5.8 magnitude earthquake. (You can "relive" the earthquake experience with this Reuters video.)
Based on detailed engineering assessments conducted following the August 23, 2011, temblor the National Park Service has determined that loose and cracked stone, displaced mortar, and other exterior damage up and down the 127-year old 555 ft, 5-1/8 in tall unreinforced masonry obelisk require significant repairs to eliminate safety hazards and preserve the Monument’s structural integrity.
Above, an NPS helmet-cam video details some of the resulting damage.
The 12- to 18-month repair project, which NPS put out to bid on June 29, calls for removal of loose stone fragments, securing loose pieces of stone with small drilled anchors, sealing of cracked panels via sealant and/or epoxy, stone patching via Dutchman and/or mortar patches, and repointing mortar joints. The Monument’s lightning protection system will also be refurbished.
Concurrent interior repairs will address cracked stone panels, rib stones and rib-bearing haunches, and tie-beams.
A presentation of the repair summar can be viewed on the NPS website.
This will be the second time in 15 years that one of the nation's most iconic symbols has become a high-profile construction site. Between 1998 and 2000, a 565-foot high-capacity aluminum scaffolding system was erected to support a $5 million restoration program.
For that system, specially designed 2.5-ft long V-shaped corner braces with foam isolator pads allowed the freestanding scaffolding to “hug” the Monument without placing added weight on it. Blue mesh fabric provided both a decorative element to the scaffolding and protected workers.
A similar system will likely be used for the equarthquake repairs, requiring the temporary removal of a circular stone plaza, flagpoles, and marble benches at the Monument's base.
But while the Washington Monument remained open during the previous restoration project, however, the earthquake repairs will necessitate that the popular tourist attraction remain closed until work is complete.
The repairs are being funded by a $7.5 million Congressional authorization, and a matching donation from Washington businessman David Rubenstein.
And though it may be decades—if ever—before another earthquake rumbles through the DC area, the draft versions of NPS-commissioned analysis of ground motion vulnerabilities recommended no strengthening methodologies. The final report is due later this month.