The Washington Monument will remain closed until at least August because of possibly contaminated soil in the construction area, the National Park Service announced.
Modernization work for the monument's elevator is "substantially complete," NPS said.
The monument has been closed since August 2016 for elevator repairs and the construction of a new visitor screening center. The elevator has broken down several times in the past decade, including one instance in 2016 when more than 40 people were trapped at the top.
According to NPS, the newly discovered issue with the soil is below ground and poses no health risks. In a news release, NPS said the soil could have been introduced to the space beneath the Washington Monument in the 1880s, when the monument was completed.
The monument has had a variety of troubles since the 2011 earthquake damaged the interior and exterior of the obelisk. During initial repairs, the elevator within the monument was not repaired, but after several intermittent closures due to elevator issues the NPS finally closed down the monument for serious modernization efforts.
No exact date has been set for the reopening.