Waste incinerator tank’s ammonia poses safety hazard

A 12,000-gallon tank filled with anhydrous ammonia – part of an air pollution control system – poses a significant safety risk at Spokane’s solid waste incinerator.

Officials operating the garbage-burning plant want to remove the hazard and replace it with safer pollution controls.

The Spokane City Council recently approved a $1.86 million retrofit at the electricity-producing garbage plant at 2900 S. Geiger Blvd. Work is expected to begin later this year.

A leak in the existing anhydrous ammonia system, depending on the concentration of the escaping ammonia, could result in serious injury or even death to anyone nearby who breathes in the fumes. That includes plant workers, garbage haulers and others who go to the facility to dispose of solid waste.

“The problem is, this is a very dangerous chemical,” said Damon Taam, system contract manager for the Spokane Regional Solid Waste System, which oversees the city-county Waste to Energy Facility.

Wheelabrator Spokane Inc. is under contract to operate the plant and will install modifications to integrate the retrofit into the plant, he said.

Opened in 1991, the garbage plant was equipped with a system that injects a mixture of steam and ammonia into combustion chambers to reduce the levels of nitrogen oxides pollution escaping from the plant. It was judged as the best technology when it was installed, Taam said.

Not only is the tank a safety hazard, but it falls under strict government safety regulations. Fines of up to $25,000 a day can be levied for failure to comply, Taam said, and keeping up with the regulations is costly and time-consuming.

Anhydrous ammonia is commonly used as a refrigerant or farm fertilizer. Shipping accidents involving anhydrous spills, such as a 1992 train derailment in Minot, N.D., have been disasters. One man was killed and 16 others hospitalized when 100,000 gallons of anhydrous ammonia escaped from rail tankers and floated in a vaporized form over Minot.

Anhydrous ammonia, an asphyxiant, causes severe burning of eyes, skin, nose, throat and lungs. Because of its wide use in agriculture and industry, it is rated as the second most likely substance to cause death or serious injury when accidentally released.

The regional solid waste system plans to replace its large anhydrous ammonia tank with a system that derives ammonia from urea, a much safer source of the chemical, and also commonly used as fertilizer. The 12,000-gallon anhydrous ammonia tank will be replaced with a 1,000-gallon anhydrous tank to be used as a backup supply of ammonia for the urea-based pollution control system.

The urea is mixed with water and heated in a reactor to produce ammonia at a 2 percent concentration along with carbon dioxide and water, which is injected into the boiler.

The existing injection system will continue to be used. It sends an ammonia mixture into the upper regions of the garbage-burning boilers. Ammonia combines with combustion gases coming off the waste to reduce the nitrogen pollutants escaping into the air.

Nitrogen oxide and nitrogen dioxide are the two pollutants targeted by the control system, Taam said.

Both are components in summer smog and can become part of a chemical reaction that leads to a buildup of ozone pollution during hot weather, said Ron Edgar, of the Spokane County Air Pollution Control Authority.

Edgar said SCAPCA views the change as a minor modification because it simply replaces the source of ammonia and not the injection equipment itself.

The solid waste system must obtain permits for the retrofit from SCAPCA and the Spokane Regional Health District, Taam said. Officials expect to receive the permits and have ordered the new anti-pollution equipment, he said.

Wahlco Inc., of Santa Ana, Calif., is the manufacturer.

Similar conversions have been installed at thermal electrical plants in California, including the UCLA campus, Taam said.