A Wauwatosa Patch reader wanted to know why she and a number of friends, neighbors and acquaintances had detected strong "dump-like" scents wafting across broad swaths of Tosa over the past few months.
We've snooped it out, and the simple answer is: a large compost operation in our midst plus unseasonably warm weather.
Our reader said that she or others had smelled an unpleasant odor as far north and west as West Capitol Drive and North 124th Street, as far east as East Town, and as far south as Tosa Village.
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"There's some truth to that," said Mike Kreiter, superintendent of operations for the Department of Public Works. "I've had some complaints, too, and I can tell you it's not sewer work or anything else, it's the compost operation at the city yard."
However, he said, it was unlikely — pretty much impossible — for odors to have affected all those areas at any one time. It just depends on from whence the wind blows.
Kreiter said he'd gotten a complaint from a resident on North 93rd Street, some distance from the at 11100 W. Walnut Rd.
"It was one of the warm days, Jan. 4, with the wind blowing out of the southwest," he said. "They're out there turning piles, it's very warm — how often do we get 60-degree weather on Jan. 4? There's a multitude of factors determining why it's occurring and where it might be carried."
Kreiter said that even as he was speaking, "I'm looking at a steam pile" of recently turned, working compost. "If it was really aromatic and the wind was blowing, I'm certain some of it would be carried out of here."
Problems, and complaints, are new
The city collects leaves, yard waste and tree trimmings from across the city for the compost program, but it contracts with White Oak Farm Premium Organics, based in Oconomowoc, to do the actual composting.
Sandy Syburg, owner of White Oak Farm, said that no complaints had come back to him from the city — in fact, he said, he'd heard no odor complaints in the eight years he's had the composting contract with Wauwatosa.
But he acknowledged that there could well be a problem this season, one that would be solved by colder, drier, more normal winter weather.
"We could have all the components relative to a perfect storm," he said. "We're seeing unheard-of climate extremes.
"Wauwatosa is 8,000 acres and it's a Tree City. We take all the leaves from that entire community and process them in the wintertime. And it's true that processing is going much faster this year than most."
Composting 101: Piles must be turned
The city takes residential yard waste and wood waste from city forestry operations all year, but the big push for Syburg is the leaf fall from all those trees evey autumn.
The huge quantity of leaves and the other waste are ground together and formed into windrows, long lateral piles of a certain height and width. The piles are self-insulating, so microbial "cooking" action continues in the middle of the piles even in the coldest weather.
That action is called "aerobic" decomposition because it relies on bacteria and other microbes that consume oxygen. If the piles are not "turned," or stirred, regularly, oxygen in the interior of the piles can become depleted. That results either in a halt to desired decomposition or the dreaded "going anaerobic" — when other, non-oxygen-consuming bacteria take over and start to produce truly hideous smells.
To prevent those possibilities and to ensure even decomposition of all the material, the windrows must be turned, and in warmer weather they must be turned more often. And it's when they are turned that the hot, "working" compost is exposed to the public airstream.
In a typical winter, decomposition takes place at a steady, moderate pace. This winter, with unprecedented warmth until mid-January, has speeded up the process and along with other factors can have created conditions for odors to occur, Syburg said.
"I was at a trade show on Jan. 12 in Waukesha, and there were people playing golf," he said. "I changed into a T-shirt in the parking lot."
A resource for city and citizens
As for the odor problem, he said, "We're doing this in a city center, where it would be more noticeable. But it's recycling and it's a resource. We return 500 tons of finished compost to the city each year, which is offered free for residents for their yards and gardens, and the city uses it in its tree planting and to improve the quality of fill and topsoil that it removes in excavation projects.
"The city did a study when we were beginning this program (in 2004), and by doing it here instead of shipping it somewhere else, with lower transportation costs and not having to buy topsoil among other things, it was saving the city $125,000 a year — and that was when gas was $2 a gallon."
The best solution to odor problems would be normal winter weather, he said. "Cold, dry air does not pick up or carry odors well; warm, moist air does."
At any rate, he said, odors will disappear when the compost is "finished," which should be sooner than usual because of the speeded-up process.