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A South St. Paul rendering plant inspired a new Minnesota odor law. Now comes the hard part

How, exactly, does one define when a smell is not just bad, but “interferes with the enjoyment of life?” Lawmakers and state regulators are trying — at least in the Twin Cities metro area — to take on odor that invades everyday life.

Sanimax turns animal by-products and used cooking oil into things like pet food and ingredients for pharmaceuticals, cosmetics and biofuels.
Sanimax turns animal by-products and used cooking oil into things like pet food and ingredients for pharmaceuticals, cosmetics and biofuels.
MinnPost photo by Walker Orenstein

A written complaint lodged with the city of South St. Paul last Friday describes a foul, widespread odor: “Dead animal.”

“Smells rancid all over the city,” the brief complaint says. “Almost unbearable to go outside.”

It’s a common complaint in South St. Paul and nearby cities like Newport. And it’s why city officials have long clashed with a rendering plant owned by Sanimax that gets much of the blame. But despite local efforts to regulate smell, a stink apparently remains, especially on hot days, or if the wind is blowing in the right direction, said Newport mayor Laurie Elliott.

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“I have been driving in Newport and just held my breath because it was just so strong,” Elliott said.

Newport Mayor Laurie Elliott
Newport Mayor Laurie Elliott
Now, Minnesota lawmakers are taking a crack at the scent. The Legislature approved an “odor management” policy this year that gives state regulators the power to intervene when enough people complain about offensive aromas, though it only applies in the Twin Cities metro area.

Supporters say it can help improve the quality of life for thousands who live near odorous businesses. But critics at the Capitol this year questioned how the state can fairly regulate a sense that is inherently subjective.

Regulation falls to the Minnesota Pollution Agency, which is already grappling with the complexity of measuring smell. Just how bad must an odor be for the stench to, as the new law says, interfere “with the enjoyment of life?”

Rendering plant fights with South St. Paul

The Sanimax saga in particular isn’t new. The plant has been operating in South St. Paul for more than 50 years, and is now one of the last remnants of a livestock industry in an area once known for its stockyards.

Sanimax turns animal by-products and used cooking oil into things like pet food and ingredients for pharmaceuticals, cosmetics and biofuels. The company, which has paid for odor mitigation technology in the past, says the business is inherently smelly. But it’s also a recycler, using waste that it says would otherwise pile up in landfills.

“Sanimax continues to make significant investments in its South Saint Paul facility,” company officials said in a statement to MinnPost. “We are proud of the work we do in the circular green economy.”

South St. Paul says a few other businesses in town can generate bad odors, including a meat processing plant close to Sanimax. Still, city officials say Sanimax generated more than 10 times as many “verified” odor complaints as any other businesses in the city between 2015 and 2021, according to a federal district court ruling in February. The plant inspired city ordinances and a class-action lawsuit that was settled in 2020 in which Sanimax agreed to pay damages to local residents.

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South St. Paul has long tangled with Sanimax over enforcing those regulations. Most recently, in 2020, the company sued the city over an odor ordinance and zoning provisions. Sanimax said it was being unfairly targeted. In February, a district court judge ruled in favor of the city, but Sanimax appealed the case. South St. Paul officials cited that case in declining to comment on this story.

Meanwhile, Newport can’t pass any relevant odor ordinance since the company isn’t within its city limits.

Proposal for statewide odor regulations draws controversy, limited to metro

State Rep. Rick Hansen, a DFLer from South St. Paul, said it’s a difficult issue for any city or community to tackle on its own. That’s why he proposed a statewide odor management policy. “They may not have the resources or the technical ability to argue that,” Hansen said on Thursday.

Rep. Rick Hansen speaking during a House Environment and Natural Resources Finance and Policy Committee on March 8.
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Rep. Rick Hansen speaking during a House Environment and Natural Resources Finance and Policy Committee on March 8.
Under the version of his plan that passed the DFL-controlled Legislature, the MPCA will have to investigate any business after 10 or more “verifiable odor complaints” within 48 hours. After that, MPCA regulators could order a management plan. Hansen’s legislation exempts on-farm animal and agricultural operations, municipal wastewater treatment plants, cars and transportation facilities and a few other smelly businesses and activities.

“I would also invite you all to my district in the summer,” Hansen told lawmakers during a hearing for his proposal in March. “Maybe on an 80- or 90-degree day.”

Rep. Leigh Finke, DFL-St. Paul, said people often complain about the smell from a paper plant in the Midway neighborhood of her district. “It stinks,” Finke said. “This is a problem in the city. That’s probably 10-15,000 people who are having this odor that they consider unpleasant.”

Rep. Leigh Finke speaking during a House Environment and Natural Resources Finance and Policy Committee on March 8.
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Rep. Leigh Finke speaking during a House Environment and Natural Resources Finance and Policy Committee on March 8.
Before it passed, the odor policy drew questions, however. Some Republicans, the Minnesota Chamber of Commerce, and at least one rural Democrat expressed concerns about the potential impact on businesses like an International Falls paper mill.

And there was debate over how exactly to define and measure when something is smelly enough to require state intervention.

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Rep. Steven Jacob, a Republican from Altura in rural southeastern Minnesota outside of Winona, said a vegetable packing plant in his district embodies that conundrum. “Heavy odors of sweet corn in my town, some people like it, some people don’t,” Jacob said.

Meanwhile, Rep. Roger Skraba, R-Ely, said he represents a wide swath of potentially stinky businesses, including that paper plant in International Falls, a mine in Silver Bay, even a famous donut shop in Grand Marais. “Everything has an odor,” Skraba said.

Donut shops aside — restaurants are exempt — DFL Rep. Dave Lislegard of Aurora said he worried people who “don’t agree with certain industries” could use the legislation to force unfair investigations. He said the bill was “broad and sweeping” across the state.

Rep. Steven Jacob speaking during a House Environment and Natural Resources Finance and Policy Committee on March 8.
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Rep. Steven Jacob speaking during a House Environment and Natural Resources Finance and Policy Committee on March 8.
There were enough objections for Hansen to narrow the bill. What passed the Legislature applies only to the seven-county Twin Cities metro area, not in Greater Minnesota, for instance.

That two-region split was common for DFLers this year when passing environmental regulations that were somewhat controversial among their more conservative members representing either rural areas or regional centers in Greater Minnesota. But Hansen also said there was merit to limiting such a new policy that might have broader implications for agriculture and other industries outside the metro.

The final legislation defines an objectionable odor as a smell that is “injurious to public health or welfare” or “unreasonably interferes with the enjoyment of life” or the use of property.

The ‘Nasal Ranger’ and the complex world of measuring and regulating odor

When, exactly, an odor is actually injurious or interferes with life was left up to the MPCA. The agency is still in the beginning stages of working that out.

Aneka Swanson, an air policy planner for the MPCA, said the state used to have odor regulations until the 1990s, when the Legislature repealed them.

“I think a lot of the questions I have are about implementation,” she said. “How do we make sure that this works because that was the failure of the previous rule. It was really difficult to implement and was reliant on standards that quickly became old and outdated.”

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Swanson said the MPCA is looking at how other states and cities have restricted odor. It may be easier to determine when a smell is a public health risk, because the state knows when chemical emissions start to become a health issue, Swanson said. The question of interfering with quality of life is more subjective.

In its effort to limit smells, South St. Paul uses a device meant to detect and measure odor called the Nasal Ranger. It looks like a small telescope, but one planted on your nose rather than your eyes. The company that makes them, St. Croix Sensory, is based in Stillwater and is a leader in the field.

The device rates the intensity of odors on a numerical scale in an effort to create an objective standard for a subjective sense. It works by diluting air at different levels to count when a user can whiff an odor.

Field Olfactometer
St. Croix Sensory, Inc.
Field Olfactometer
Michael McGinley, the company’s president, said there are other ways to measure smell and model its potential impact on surroundings from the source. But he said the Nasal Ranger is good at documenting objectionable odors on the “back end,” once the smell has actually reached the public. And he said that’s the most common way of approaching the issue in the U.S.

“There’s a problem, people are complaining, now what do we do about it,” he said.

Michael’s father Chuck invented the Nasal Ranger. Chuck had worked for the MPCA as an odor inspector, and even told the New York Times last year that he played a very small role in developing “scratch-and-sniff” technology.

About 10 states allow the Nasal Ranger methodology to measure smells for odor laws, including North Dakota, Michael McGinley said. McGinley said in his experience rendering plants are a common source of complaints, as are landfills, compost facilities, wastewater treatment plants, and marijuana production.

How Minnesota’s law might affect marijuana operations isn’t totally clear. But the Legislature, separately, said the new state agency regulating cannabis must create standards to limit smells. The MPCA also regulates hydrogen sulfide emissions from agriculture, which gives off a rotten egg smell.

Asked about the challenge of regulating smells that some find more offensive than others, McGinley said the complaint-based regulations in Minnesota mean at least some people find the smell objectionable enough to warrant a closer look.

Swanson said how to act when people are split on a smell is “definitely something we’re going to have to figure out.”

“I do not know at this point,” she said.

Sanimax itself weighed in after the law passed, writing in a letter to the MPCA an objectionable odor shouldn’t be boiled down to a single number. A smell emanating from a bakery could rate high on the Nasal Ranger, meaning it is potent. But few would find that objectionable, Sanimax argued.

The Wakota bridge spanning the Mississippi River near the Sanimax rendering plant connects South St. Paul and Newport.
MinnPost photo by Walker Orenstein
The Wakota Bridge spanning the Mississippi River near the Sanimax rendering plant connects South St. Paul and Newport.
Sanimax said the MPCA should consider using trained investigators to deploy a method of determining bad smells known as FIDOL — which stands for frequency, intensity, duration, offensiveness and location. By contrast, the legislation says regulators can take the opinion of a “random sample” of people exposed to the odor as the MPCA investigates.

The company also suggested sniff training a large enough pool of people who can be called on for that random sample. That could include repeatedly exposing people to different odors to improve their ability to detect them. “If there were no criteria, the results of the odor investigations could substantially vary and would lead to inconsistent enforcement and results,” says the letter, signed by attorney Andrew Davis.

In its statement, the company said it wants to ensure that odor rules are “clear, sensible, and fair for all parties.”

The MPCA’s Swanson said a Nasal Ranger is one tool they could use, but she said that only gets at the intensity of smell and said states often rely on those FIDOL factors. (McGinley said inspectors in other states typically build up evidence by taking multiple readings, like staying at the house of someone who complained for an hour, not just by using the Nasal Ranger once and calling it good.)

Elliott, the Newport mayor, said the city was getting lots of complaints in 2019 and 2020. After the class-action lawsuit was settled, Newport said she believed the city would either have to invest time and money into suing Sanimax itself or look for other avenues to limit odor. 

“I’m very happy that we have some legislation that gives some control to not just our residents but residents of any community around any odor-producing business that affects quality of life,” Elliott said. “That affects your ability to be outside in the summer, to ride bikes, to garden, to play, to take your kids to a playground.”