Vol. 4, No. 6
June 2012

Laboratory responds to largest fire in county history

The largest fire in Johnson County history began on Saturday, May 26, and burned so hot it turned melted tire shreds into pyrolitic oil and created a plume of smoke that spanned the horizon for nearly 15 days.

A landfill staffer bulldozes the grounds of the landfill to fight the fires on the night of Saturday, May 26. (Photo by Rick Fosse, courtesy of the City of Iowa City)

While the 7.5 acres of the Iowa City Landfill burned, the State Hygienic Laboratory - on behalf of Johnson County Public Health - tested air samples collected near the fire and from multiple locations in the county for the presence of environmental contaminants. The Laboratory also tested samples from a collection pool that held more than 100,000 gallons of volatile pyrolytic oil created when the tires that lined the landfill cell burned.

"Air samples were collected by Hygienic Laboratory staff that Sunday and on Memorial Day to assess the quality of the air in terms of chemical contaminants in the smoke plume," said Michael Wichman, Ph.D., associate director of Environmental Health Programs. "Air testing continued well into the next week in Coralville, and additional, urgent testing of pyrolytic oil byproduct was provided by our Ankeny staff."

Iowa City officials initially considered using a specialized wetting agent to extinguish the fire. Because of the low probability for success and the potential environmental hazards posed by the runoff, the city opted to contain the fire and let it burn itself out. Its strategy later shifted to a "stir, burn and cover" method that used heavy equipment to turn the burning tires to accelerate the combustion process, and then topped them with a layer of clay soil after combustion was nearly complete.

Shifting winds at times changed the direction of the plume, moving it toward Iowa City and increasing potential human exposure to particulate matter and other irritants. Pollutants in the plume rapidly diluted as the smoke traveled away from the landfill, according to Johnson County Public Health. The agency issued a health advisory recommending that those in the path of the plume stay inside, particularly if they were elderly, children or people with a respiratory or heart condition.

The pyrolytic oil was removed from the landfill and transported to an incineration facility in four different states and Canada.

"We finished covering the fire on June 10," Rick Fosse, director of Iowa City Public Works, reported on June 21. "We believe that the shallow areas of the fire are extinguished. We don't know yet about the deeper areas. We are now working on a safety plan before we open areas back up to examine them and begin the cleanup of the fire byproducts."

Matt Mainprize checks the pre-sampling pressure to confirm that a canister used to collect air samples is evacuated.

In addition to officials from Iowa City and Johnson County, the Hygienic Laboratory collaborated with Iowa Department of Natural Resources, the Environmental Protection Agency and the University of Iowa's departments of Chemistry and Chemical and Biochemical Engineering.

"I cannot commend our staff enough for the long hours and rapid testing services that they provided to better understand the chemical makeup of the smoke as well as the oil byproduct," Wichman said. "Matt Mainprize, our chemist who performed much of the sampling and analyses, commented, 'This is why we are here. It is part of our job to provide testing services as needed, 24/7, 365 [days per year].'"