TOOELE -- News that Deseret Chemical Depot was on the list of military closure recommendations Friday was no surprise.

The depot has been on track to be closed once its stockpile of hazardous chemicals is completely destroyed, but just when the closure will be completed remains a mystery.

"We always knew we would close," said Col.Raymond Van Pelt, commander of the depot where chemical weapons have been incinerated since 1942. "This is good news."

Closing the base means the chemical weapons will be gone, meeting an international mandate. But when the final stage of the closure -- the decontamination and cleanup of the nearly 20,000 acre facility -- gets under way was still unclear.

The depot's only purpose is to dispose of chemical munitions once used by the military. Under the international Chemical Weapons Convention treaty, the U.S. must do that by 2012. It is one of eight such facilities around the country and one of three recommended for closure.

Located in Stockton, about 45 miles southwest of Salt Lake City, the depot once held 44 percent of the country's chemical weapons stockpile -- more than any other site. It has been the primary demolition site for the deadly sarin, VX and mustard chemical agents. Sarin destruction was completed in 2002 and the final work on VX gases is expected to be finished this summer.

The final phase of demolition on 7,000 tons of mustard agents is slated to begin in 2006 and could take between two and three years, Van Pelt said.

That would be followed by decontamination and cleanup of the site, including the demolition of storage facilities.

Van Pelt was uncertain Friday how long the cleanup process might last. Under the realignment plan announced Friday, military installations are expected to close within two to six years, he said.

"We will not close the depot until we destroy all the munitions," Van Pelt said, adding that is possible the depot could make the 2012 date.

Jason Groenewold of HEAL Utah, the grassroots group that works to keep nuclear and toxic wastes out of the state, calls the projection "extremely optimistic."

"Nothing has been done on schedule thus far and the mustard agent will likely be the most difficult part of the stockpile to destroy," Groenewold said.

"The Army had originally projected to be done incinerating all the chemical weapons by 2004 and yet we're barely at the halfway point."

The military has a sketchy track record when it comes to cleanup of other installations around the country, Groenewold added, so the depot cleanup bears close monitoring.

"The military priorities have been to build new bombs, not to clean up after the old one, we see that time and time again," he said.

Van Pelt said the Army does not know the extent of the contamination at the depot, or how much it will cost to clean things up to the point where the land could be used for other purposes.

However, some initial assessments of several open pit areas where munitions have been incinerated have estimated cleanup costs of as much as $2.5 billion, he said.

In the end, the extent of the cleanup will depend on an assessment by the Army Corps of Engineers and the allocation of resources by the defense department and Congress.

Under Base Realignment and Closure list issued Friday, the project will be prioritized, Van Pelt said.

He suggested that if appropriately decontaminated, the area could be converted to industrial or residential uses.

But he also acknowledged that, "there are some areas that will be environmentally restricted and will take significant resources to clean up."

Tooele County commissioner Matt Lawrence said he doesn't believe there is realistic possibility that the property will have a future use.

"It's large and it's contaminated significantly," Lawrence said.

Still, commission chairman Dennis Rockwell said the Army has "been a good neighbor" and he trusts that they will do everything they can.

Also unclear is the economic hole the loss of the depot might leave in Tooele's economy. Neither Rockwell or Lawrence said they knew how much money the depot, which has a $200 million annual operating budget, brings to the county each year, although about two-thirds of its work force lives in the area.

The depot's 1,500 person payroll will change and diminish as the facility completes the demolition and moves toward closing. Only three of those on staff at the depot are Army personnel. Of the remainder, 500 are civilian employees and 1,000 are contractors, he said.

Programs and other resources will be available to help employees, the city and county make the transition.