HONOLULU (AP) — An Army chemical weapons disposal plant that handled nerve gas and other deadly agents has been properly cleaned and closed, the U.S. Environmental Protection Agency announced Monday.

The dismantling of the Johnston Atoll Chemical Agent Disposal System facility on the now-uninhabited Pacific island about 890 miles west-southwest of Honolulu took about three years, ending in 2004.

Sarin nerve gas, mustard gas and blister agent dating back to World War II were incinerated at the facility, known as JACADS, along with more than 400,000 rockets, projectiles, bombs and mortars containing chemical agents, including the deadly nerve agent VX, officials said.

The EPA said its multiyear review found the Army met all permit requirements for closing.

"Over the 15 years of JACADS' construction and operation, the EPA closely monitored the facility to ensure safe operations and prevent chemical releases," said Jeff Scott, director of the EPA's Pacific Southwest Region's Waste Management Division.

"Our closure decision brings a successful end to this project to safely dispose of 4 million pounds of toxic chemical weapons while protecting the former workers and wildlife on Johnston Atoll," he said.

The EPA said its closure approval "assures protection from impact of JACADS for not only human health, but also for the ecology and environment."

The Army was required to decommission JACADS after the facility in 2000 destroyed the last of over 400,000 obsolete chemical weapons collected from Okinawa, Japan, and other U.S. military bases in the Pacific Basin and West Germany between 1971 and 1991.

The EPA said its environmental oversight helped the Army incinerate the toxic chemicals by destroying the poisons at the molecular level. The weapons had been stored in concrete igloos on the 1-square-mile island.