Daniel Gach and Emma Cardini of WJE conduct exterior assessment of the Washington Monument Sep. 28, 2011.
The Washington Monument is set to open to the public on May 12 for the first time in nearly three years. The closure was necessary when the structure was damaged by a 5.8 magnitude earthquake that occurred 84 mi. southwest of Washington, D.C., on Aug. 23, 2011.
According to Carol B. Johnson, current acting legislative specialist for the National Park Service (NPS), assessment started the day after the earthquake. Actual notice for the construction contract came in November 2012.
The full dollar amount of the contract is $15 million. Half comes from appropriated funds, and half from a donation from philanthropist David Rubenstein.
The contract was awarded to Perini Management Services Inc. of Framingham, Mass., and the onsite project manager is Bob Collie.
“The scope of work includes, but is not limited to, removing and/or securing loose stone fragments, stone patching, repairing cracks, re-pointing, replacing the lightning protection system, and repairing and strengthening rib joints,” Johnson said.“The Washington Monument is the tallest free-standing masonry structure in the world, and a national icon. Because of its prominence, the construction itself was of major interest to D.C. residents and visitors.”
Johnson noted that the biggest challenge was access to both assess and repair the damage.
Following the earthquake, stones in the monument had spalling and cracking, primarily in the upper levels.
Wiss, Janney, Elstner Associates Inc. (WJE) was chosen to investigate the earthquake damage.
“To fully determine the scope of damage and to ascertain the structural stability of the monument, a team of engineers with specialized expertise in the performance of stone structures subject to seismic loadings was required,” the company Web site noted. “The team also had to possess unique skills in rope access techniques in order to complete close-up inspections of the monument exterior.”
WJE reported that they assembled a team of engineers and architects with the necessary expertise to quickly and economically assess the structural stability of the monument and overall impact of the seismic event on the natural stone and historic fabric of the monument. Using specialized rope access techniques, engineers and architects that comprise the WJE Difficult Access Team (DAT) rappelled down the monument exterior, documenting the damage and removing loosened stone fragments. The DAT used Tablet PCs (iPads) to record observations on drawing overlays so that interior and exterior conditions could be documented electronically and used to develop repair documents. WJE developed temporary repairs to minimize water intrusion, then completed a seismic study to assess the monument’s vulnerability to future potential earthquakes and a comprehensive set of construction document drawings and specifications to guide the permanent repair and restoration of the monument.
Damage included a “debris field” of mortar and pieces of stone around the base of the monument, several “substantial” pieces of stone dislodged inside the memorial, and a crack in the central stone of the west face of the pyramidion 1-in. (2.5 cm) wide and 4 ft. (1.2 m) long. The elevator system also was damaged.
Major subcontractors for the repair include UBS for scaffolding; Lorton Stone for stone work and repairing rib joints; and Grunley for removing and/or securing loose stone fragments, stone patching, repairing cracks, re-pointing, and replacing the lightning protection system.
“The most notable aspect was the aluminum scaffold erected for the work that mimicked the profile of the monument,” Johnson said. “It was decorated in horizontal and vertical mesh to provide a block and joint appearance. The monument was also backlit inside the scaffold to provide a glowing effect. The same scaffold system used for the repairs in 1999 was erected for the earthquake repairs. UBS, Lorton, and Grunley worked on the repointing of the monument in 1999 to 2000.”
According to the NPS, repairs to the exterior of the pyramidion and monument shaft included the removal of loose stone fragments, the securing of loose pieces of stone with small drilled anchors, the sealing of cracked panels via sealant and/or epoxy injection, complete stone patching via Dutchman and/or mortar patches, the repointing of mortar joints, and the removal/reinstallation of the lightning protection system.
On the interior, work included the structural repair of cracked stone panels, rib bearing haunches, cracked tie beams, and displaced rib stones; the sealing of cracked panels via sealant and/or epoxy injection; and the repointing of mortar joints.
James M. Perry, chief of resource management for the mall and memorial parks, noted that the project is not meant to be an aesthetic repair. The monument includes lots of patches, Dutchman, and areas where mortar has been added over the years. They wanted to maintain the existing character of the structure, which he said, “shows its age really well.”
A total of 150 Dutchman patches were reportedly used. When crews ran out of spare marble that was available for repairs, a company was found that had salvaged old marble steps from homes in Baltimore, and the marble originally came from the same quarry as the marble used in the monument
The Washington Monument was built as a tribute to George Washington, and was constructed between 1848 and 1884. It is the tallest unreinforced masonry structure in the world The walls taper from over 12 ft. (3.6 m) thick at the base to 18-in. (45.7 cm) at the top The pyramidion that caps the structure is covered in 7-ft. (2.1 m) wide hung marble panels with an inscribed block of cast aluminum at the apex.
The monument includes marble, granite, and bluestone gneiss, and stands 555 ft. 5-1/8 in. tall. This makes it both the world’s tallest stone structure and the world’s tallest obelisk. The total weight of monument, including the foundation, is 81,120 long tons (90,854 short tons). It includes a total of 36,491 blocks, and is said to sway 0.125 in. in 30-mi.-per-hour wind.