Anhydrous leak prompts evacuation

INDEPENDENCE, Mo. -- Two hundred pounds of anhydrous ammonia gas escaped Sunday from a business inside a cave complex, and about 400 people living within a half-mile of the site were asked to leave their homes as a precaution. No injuries were reported.

Three workers at Independence Ice Co. noticed a gas cloud forming inside one of the caves around 7:15 a.m. and called 911, police spokesman Bill Pross said. Firefighters sealed off the area and called in a hazardous materials team.

A pop-off valve detected high pressure in a holding tank for the ammonia and shut down a recirculating pipe system, Pross said.

"If the valve wouldn't have worked, there would have been a significant explosion and 6,000 to 7,000 pounds of ammonia would have been released," he said. "That would have been a real problem."

Instead, a hazardous materials crew checked the caves twice and determined the area was safe. The ammonia that went into the air quickly dissipated in the heat and southerly wind, Pross said.

Residents were allowed back into the neighborhood about 12:30 p.m. No injuries were reported from the heat or from the ammonia fumes, which can cause burning in the lungs and on the skin, Pross said.

Independence Ice has no history of mechanical problems, Pross said.

"It was a freak deal, but fortunately, mechanically everything worked as it should have," he said.