Airport board approves different kind of fertilizer

Jenny Gessaman
A man stands in front of a long and large pile of what appears to be dirt and compost.

Michael Howell stands near the front of one of the Lewistown Wastewater Treatment Plant’s biosolid compost piles. Several more fill the field by the plant, with each pile representing a different year of biosolids.

Photo by Jenny Gessaman

The Lewistown Municipal Airport Board approved the use of sewage sludge on the facility’s farm lease on Aug. 10. Airport Manager Jerry Moline reported the city would periodically haul the material to the fields.


Wait . . . what?

To be fair, most people want nothing to do with the Lewistown Wastewater Treatment Plant and its byproducts. However, most does not include everyone. Wastewater Operator Michael Howell has seen gardeners and contractors take something away from the plant: compost, made from exactly what one would expect.

Biosolids is the official term, and is what will be spread on the airport’s farm lease. The label is one that has to be earned, though, according to Howell. Biosolids start out as the material coming in from the sewers, and is run through the treatment plant.

“Our whole process is to get rid of the solids [in the wastewater] and treat it,” Howell said.

He explained treating it means following very specific guidelines to remove things dangerous to people’s health, such as pathogens, or microorganisms that can cause disease. Part of the process is keeping it in a tank at 68 degrees for 20-40 days, allowing bacteria to break down organic solids and then starve.

After treatment, the plant is left with two products: effluent, treated liquid waste discharged into the creek, and what is called “sewer sludge.” The disposal of this semi-solid byproduct is regulated, and limited: It can be incinerated, buried in a landfill or, in Lewistown’s case, used for land application.

But residents should not worry, or be disgusted. This option is still fully regulated, according to Howell. In fact, to become a biosolid, sewage sludge undergoes several processes after wastewater treatment.

One of these is the drying beds, where the material is dried into a solid, usable form. The solids are tested for levels of heavy metals, bacteria and nutrients before they can be removed.

Howell said the plant’s next step is to compost it. By this point, it looks like dirt, and wastewater staff mix it with leaves and grass clippings. The pile sits for at least a year before it is officially a biosolid usable for land application.

Howell has seen a range of takers, from contractors looking to fill in yards, to gardeners looking to build or fertilize their beds. He suspects it’s especially good for tomatoes: Howell’s seen several people growing the vegetable in biosolid compost.

“A lot of people are turned off by using biosolids to grow things, but once people use it, they come back,” he said. “Most people are like ‘Ew,’ but if you think about it, people use cow fertilizer and the EPA doesn’t test that.”


But is it safe?

Robert Brobst, EPA Senior Environmental Engineer stationed in Denver, confirmed the EPA does not regulate fertilizer from manure. The department does regulate, and act as enforcement, for biosolids though.

For three decades, Brobst has experienced the disgust and doubt surrounding biosolids and their use. He has developed a list of things people commonly worry about, such as toxins.

“Sewage sludge, as well as the water, is a microcosm of what the city is and what the city does,” he said.

Brobst explained a city’s activities are reflected in its wastewater: fertilizer from gardens and fire retardants from an emergency can all wash into the sewer. He said there was more to consider than what was present, though. Dilution, or a set amount of toxin being mixed with more and more wastewater as it nears a treatment plant, is important, too.

“In many cases those toxins become so low, they’re not a concern, or they are consumed by the bacteria in the treatment plant,” he said. “To be toxic, not only do you have to have the element or compound, you have to have it in certain amounts.”

Heavy metals, accumulated in urban areas, are another biosolid concern. Brobst pointed out those levels are regulated in treatment plants. By the time sewage becomes sewer sludge, and before being made into biosolids, almost all heavy metal levels are at background soil concentrations.

“If you went out to your garden, you would find the same stuff in the same amounts,” he said.

Brobst admitted biosolids did have living organisms, but explained this was not a bad thing.

“One of the things you do not want is to have a sterile treatment come out,“ he said. “You cannot have that because you’ve created the ideal food source.”

Brobst explained any stray salmonella, for example, would see sterile biosolids as a buffet and breeding ground.

Concerns such as these were foremost in the mind of the Lewistown Municipal Airport Board, according to Chairman Steve Mosby. A chemical analysis by the City, along with individual research on board members’ parts, helped sort out the facts.

“It’s important to realize how this stuff is made and treated and disinfected,” he said. “It’s not sterile, but it’s not pathologic.”

The board also looked at heavy metals, and Mosby said the highest metals were at most, 10 percent of the allowed limit.

“It’s a pretty simple deal, in my mind,” he said.

Mosby sees the biosolids as a three-way win for the City, the farmer and the airport.

“The city’s looking for a cheap, cost-effective way to get rid of its sludge, and we’ve got a farmer who understands that it’s like cow manure,” he said.

The hope is that spreading the biosolids on the farm lease will improve its soil.

“The soil out there, well, there are areas that are rocky and not very fertile,” Mosby explained.


Biosolids aren’t new

Biosolids are not new in the fertilizer field. Ryan Hansen, CHS Big Sky Agronomist in Denton, has heard the term before.

Biosolids are more common back East, where Hansen grew up, in states like Wisconsin and Minnesota. The material is viewed, and priced, a little bit higher there.

“Home gardeners and golf courses used biosolids as their primary fertilizer,” he said.

The demands from those two consumers created too small a supply and too high a price for agricultural use, according to Hansen. He expected a different response in Central Montana, though.

For one, the Lewistown Wastewater Treatment Plant gives away biosolid compost. For another, locals may have a different view socially of the material.

“It’s like comparing Kalispell to Winifred: There are different concerns and different values for people living in those places,” he said.

Before considering biosolids for local agriculture, even before looking at how much is available, Hansen would look at the nutrient content. The amount of elements, such as nitrogen, would determine if the material was an appropriate fertilizer.

Hansen has not dealt with biosolids during his work in Montana, but he sees another potential obstacle for the fertilizer choice. Its relatively obscure status and its unique source could create doubt.

“It takes time to build trust with a product, and get people comfortable with using it,” he said.

Brobst summarized people’s most common biosolid fear.

“The presumption is, something will go wrong,” he said. “We [the EPA] are making a presumption it will not, because in the last 20 years, we haven’t had a case besides blatant violations.”

For Brobst, biosolids are the ultimate form of recycling.

“I go out and harvest the wheat that makes the bread I eat,“ he said. “It goes back to the wastewater plant, and the biosolids are applied to a wheat field.”

He approached the recycling argument from a more farmer-friendly angle.

“You’re improving your soil,” he said. “People always talk about the fact that agriculture cares for the land. This is one example of that. All of the minerals that go to grow that plant leave when you harvest. Here, you’re putting them back.”



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