St. Helens, Ore.-A tiny leak in a safety relief valve atop a 500-ton tank at the Dyno Nobel nitrogen fertilizer plant here released between 300 and 700 pounds of anhydrous ammonia over nearly five days without causing any serious problems, according to Plant Manager Greg Godfrey. There were no injuries, no plant or community evacuations, and no interruptions in the operation because of the leak, which took place between April 23 and April 28. A truck driver noticed the odor and alerted emergency responders. “We’re still calculating the amount,” Godfrey told Green Markets. “But data from our instrumentation indicate that the leak began on that Wednesday at 11 a.m. and wasn’t detected until 2 a.m. Monday.” Godfrey said it was in one of two safety valves that are part of the overpressure system, which was reconditioned by a certified service shop just two weeks prior to the leak. He described the leak as so small that it didn’t trigger the alarm system and was not obvious to plant service personnel, who are on duty around the clock. Godfrey figures the fumes dispersed on their own until a change occurred in the weather, when a truck driver passing by smelled ammonia reported it to the Columbia River Fire and Rescue. The plant night supervisor shut off the leak before the emergency crews arrived. Godfrey said that once a week an operator goes several stories up to the top of the tank to perform a routine inspection, but wasn’t scheduled to make the climb until after the leak was found. Several employees who live less than a half mile away detected nothing, and the same was true for those at a utility office and quarry just across the street. Godfrey said the ammonia is used primarily to produce UAN, but some is sold directly to farmers from the plant, which employs seven. The leak also was reported to the Oregon Dept. of Environmental Quality, where a spokeswoman said that because the incident was accidental the department will not take action against the company.
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