When a magnitude 5.8 earthquake shook the Eastern Seaboard in summer 2011, it jolted engineers of the U.S. National Park Service (NPS) into action. Within two days, agency engineers and a team led by structural engineer Tipping Mar, Berkeley, Calif., were at the Washington Monument, assessing damage to one of the nation's most iconic landmarks. Since then, NPS and its engineers and contractors have worked to tap available resources, leverage lessons learned and expedite repairs. After nearly $15 million of work, the marble obelisk, more than 555 ft tall, is on track to reopen this spring.
Under an existing indefinite delivery-indefinite quantity (IDIQ) contract, Tipping Mar mobilized quickly after the Aug. 23, 2011, earthquake and brought in subconsultant Wiss, Janney, Elstner Associates (WJE), Fairfax, Va., to help conduct assessments. While some investigations were conducted inside the monument, WJE also deployed its difficult access team to rappel along the monument's exterior and document damage.
The team's findings revealed "cracking and spalling of the exterior marble and underlying stone masonry elements as well as loss of joint mortar and de-bonding of cementitious patching material." At above 490 ft high, the pyramidion section proved to be particularly vulnerable, according to the report. Despite the damage, the team found that the structure remained fundamentally sound and could be reopened following repairs. There has been no public access to the monument since the earthquake.
"The report showed that the monument itself, which is non-reinforced masonry, did amazingly well and responded like we hoped it would," says Cherie Shepherd, NPS project manager and project specialist. While the report showed that there is no effective way to seismically reinforce the monument, it proved that the structure would act effectively in the unlikely event of another significant earthquake, she says.
With seismic concerns allayed, the team set about planning its repair work. Members were able to leverage extensive information from previous monument repairs conducted in 1999 and 2000. WJE sent its special team of engineers and architects back out on the ropes armed with digital documents from the previous restoration work.
"They had that documentation loaded into their iPads," says Daniel Lemieux, principal and unit manager at WJE. "So as they rappelled the monument, they could look at the damage and compare it to previous damage that had been documented."
The ropes team photographed damaged areas, salvaged some loose pieces of masonry and prepared its repair drawings, based on the findings. "[The drawings] break down every elevation and every level of the monument," says Michael Morelli, NPS primary project manager.
Team members "developed a set of working drawings and showed where repairs were needed and what type was necessary [in each damaged area], whether it was a crack that we fill with grout, an epoxy repair or if a Dutchman repair was needed," he says.
To carry out the repairs, the team again leveraged its past experience. Contractor Perini Management Services, Framingham, Mass., which holds a multiple award task order contract (MATOC) with the U.S. Dept. of the Interior that is administered by NPS, teamed with several firms that worked on the 2000 project, including Grunley Construction, Rockville, Md.; Lorton Stone, Lorton, Va.; and Universal Builders Supply, Hyattsville, Md.
"We knew they had prior experience and we'd be able to expedite submittals and draw on their experience," says Robert Collie, project manager with Perini Management Services.