U.S. Postal Service officials expressed confidence yesterday that the year-long effort to develop a safe and effective means of ridding the postal plant on Brentwood Road NE of anthrax spores will pay off this weekend, when a full fumigation is scheduled to begin.

During a community meeting in Northeast Washington and at an earlier news briefing, postal officials detailed their plans for the decontamination, the first stages of which will begin at 3 p.m. Saturday and continue into next week.

The process calls for 2,000 pounds of chlorine dioxide gas to be pumped into the quarantined facility, which has been shut since October 2001 after two letters containing anthrax spores passed through the building on their way to Capitol Hill. Chlorine dioxide is a disinfectant used to purify drinking water that scientists have learned is lethal to anthrax spores when maintained in certain conditions.

Postal and city officials told residents and postal employees at a town hall meeting at Gallaudet University last night that the gas does not pose a danger to postal workers, residents and businesses.

"We don't anticipate . . . any problems," Thomas G. Day, the Postal Service's vice president for engineering, told an audience that filled half the university auditorium.

Day and other officials stressed the many precautions they will take during fumigation. A specially equipped Environmental Protection Agency bus will drive around the building and monitor air quality. The Postal Service has also installed 26 air monitors surrounding the building. The sealed building has been rechecked for cracks, and a safety perimeter of 282 yards will be established, officials said.

The fumigation will stop if gas is detected in the area at 25 parts per billion, far below the federal safety standards for exposure to the substance, officials said.

Despite the reassurances, several neighbors and postal workers at the meeting expressed concern. Three workers at the plant said they were apprehensive about returning to work in the building, saying they had confidence in the technology but not in postal management.

"Last year, they were ignorant [about how to respond to an anthrax attack], but this year, they're experts," said James Harper, a Brentwood worker and member of Brentwood Exposed, an employee support group.

Day said that the same procedures used in the successful cleansing of the Hart Senate Office Building last year are being employed at the postal plant, including the use of chlorine dioxide gas.

On Saturday, the gas is scheduled to be pumped into the building and kept inside for several hours. The full exposure of the gas is expected to be completed Monday, when scrubber systems that turn the gas into harmless wastewater will operate for an additional 20 hours, officials said.

About Thursday, crews are expected to enter the facility and begin collecting 8,000 spore strips and 4,000 samples that will determine whether the fumigation was a success. Some 30 days later, a committee of specialists co-chaired by the D.C. Department of Health and the EPA will review the results and determine whether additional cleanup is needed.

Day said that if all goes well, postal workers would return to the facility in mid to late spring. He said he did not expect any problems because of this weekend's cold weather.

The Brentwood postal facility has been closed since October 2001 after anthrax spores were found.