TULALIP – A chemical weapons depot on the Tulalip Reservation that was abandoned by the U.S. military 60 years ago now won’t be cleaned up until February.

Contractors for the U.S. Army Corps of Engineers announced their new timeline for the project in a public meeting Thursday evening.

Work at the site, which has been on hold since August, is scheduled to resume Dec. 11.

Work initially began in May, when crews hired by the Corps began excavating for anything that might have been left behind when the military closed what was known in the 1940s as a Backup Ammunitions Storage Depot.

The military stored ammunition, including chemical weapons, on nearly 700 acres of the site, according to federal documents.

Since crews began investigating early this year, they’ve found dozens of unusual deposits buried throughout about 10 acres of the site.

Work stopped in August, when workers who complained of a strange odor were taken to a local hospital.

That same day, the workers uncovered broken vials that may have once contained a liquid form of mustard gas, Corps Project Manager Rodney Taie said. The finding was unexpected, he said.

The discovery led to a federal requirement that the cleanup be completed within six months.

The area is now covered with a pressurized tent designed to contain any vapors that may escape from the ground, Taie said.

“The tent is to protect in case we do come across some additional glassware that are intact, to help prevent any release,” he said. “It’s to protect the general public and also the workers themselves.”

The cost of the project has doubled, to about $4.5 million.

Reporter Krista J. Kapralos: 425-339-3422 or kkapralos@heraldnet.com.