Roadkill revival

State using composting to dispose of dead deer

The Montana Department of Transportation is using an innovative method - composting - to dispose of roadkill in the Bitterroot Valley.

For the past year, the department has been composting dead deer picked up along state highways. The practice has proven so effective, it could be expanded to other parts of Montana.

Roughly 600 to 700 deer are killed on U.S. 93 every year along the 80-mile section from Lolo to Lost Trail Pass, according to a department press release. The bodies are collected and disposed of by state highway maintenance crews.

"It's an everyday thing," said District One Maintenance Chief Doug Moeller. "Fall and spring are the busiest periods, with animals traveling to and from their wintering grounds. We can pick up as many as 14 dead deer per day."

Previously, crews would haul a load of roadkill to the Missoula landfill, or they would look for an inconspicuous location where the deer could be left to decompose naturally.

However, rapid growth in the Bitterroot is making it more difficult to find a good place to dump carcasses, and taking them to the landfill is expensive. Moeller figured it costs about $135 per deer, including labor costs, transportation costs and the landfill fee.

A year ago, the department decided to try composting at a small facility near Victor.

"It's worked very well," said Cora Helm with the department's hazardous waste section. "We've successfully composted more than 500 deer."

During the composting process, deer are covered with sawdust, wood chips and other natural vegetative waste. Bacteria, fungi and other microbes break down waste material to produce a rich humus that can be used to enrich soil. The process generates sufficient heat to kill any harmful pathogens, such as e. coli and salmonella.

"The maintenance crews use four-foot thermometers to monitor the mix," Helm said. "We need to reach 130 degrees for a minimum of three days; typically, we've been maintaining 150 degrees. When the temperature drops, it's time to turn the pile."

Compost heaps have to be turned and mixed periodically to provide the air and water microbes need to decompose the waste. The ratio of nitrogen and carbon sources in the mix (the dead deer and woody material) also is critical.

"We created bins using three-foot high concrete barriers on an asphalt pad," Helm said. "Put down a layer of sawdust and chips, lay down the deer and cover them up with more sawdust. Let them compost for the summer, and by the end, [the process] is finished."

This winter, maintenance crews used some of the "hot" compost - nutrient- and microbe-rich material that was still decomposing - to start new compost piles for dead, frozen deer.

"It was hot enough to keep the process going," Helm said. "That's the beauty of it - it doesn't take a lot of effort."

The Victor facility didn't have any problems with predators or scavengers, she said, primarily because the compost piles don't smell very bad.

"When you're standing close and there's a fresh deer in it, you can smell it," Helm said. "But it doesn't take long for the smell to go away."

Flathead County landfill director Dave Prunty, who spent several years running composting operations in Spokane and California, said when it's done right, finished compost has a pleasant, earthy smell.

"It's an amazing process," Prunty said. "I'm a huge proponent of composting. It's really an art and a science. The art is in getting the proper carbon and nitrogen sources in the pile. When you have too much nitrogen, that's what generates odors."

Last year, the Flathead landfill buried almost 108 tons of dead animals, including 74 tons of large animals (greater than 200 pounds) and 34 tons of small animals.

The facility already has a small-scale composting operation for brush and "green waste," but Prunty said it would be difficult to expand that to include roadkill.

"We don't receive enough green material to make it cost effective," he said. "With the open burning laws here, people can dispose of their brush piles in other ways."

Montana is apparently one of the few states actively exploring this method of handling roadkill.

Studies regarding the magnitude of this issue are limited. However, an online Wikipedia article on "road fauna" suggested that roughly a million animals are killed on U.S. roadways every year, not including bugs.

The article said a 1994 study found that 56,666 deer were killed in Michigan in collisions with cars. The state reportedly used the statistics to estimate its total deer population.

Helm said Montana's deer compost eventually could be used in revegetation projects along state highways.

"Right now, we have to buy compost," she said. "There are a lot of roadside areas that aren't being revegetated because we don't have the money. This could help."

Based on the results from the Victor project, Helm said she's hoping to start composting operations in other maintenance districts around the state, possibly in cooperation with county road departments.

"They have the same issue," she said.

Reporter Bill Spence may be reached at 758-4459 or by e-mail at bspence@dailyinterlake.com