Two South St. Paul residents have filed what they hope will be a class-action lawsuit in federal court against animal renderer Sanimax, seeking damages for years of "noxious odors" they say continue to emanate from the company's processing plant.

The plaintiffs also want Sanimax to "significantly reduce, if not eliminate" odors from the plant wafting into nearby neighborhoods. The odors, they say, are a nuisance and have had a negative impact on their property values.

Jeff Storms, a Minneapolis-based attorney handling the suit, said that the response from residents has been overwhelming and enthusiastic about "the need to have something done as to the strong, disgusting smell that's been emanating from that facility."

The suit comes a year after Sanimax, based in Green Bay, Wis., challenged South St. Paul's odor ordinance as unconstitutionally vague. Sanimax dropped its suit a few months later after city officials agreed to stop calling it a "significant odor generator," which made it liable for penalties.

Storms said residents repeatedly describe the smell from the Sanimax plant as akin to that of rotting flesh.

"They can't stay outside because the smell makes them sick," he said. "They can't open their windows."

According to its website, Sanimax collects animal hides, skins, meat byproducts and discarded oils and grease and turns them into animal feed and biofuels. Company officials did not respond to a request for comment last week.

While some mitigation efforts have been made, the suit alleges that Sanimax "has failed to install and maintain adequate technology to properly control its emissions of noxious odors."

The suit, filed Monday in Minneapolis federal court, was brought by South St. Paul residents Patricia Keech and David Newfield on behalf of residents living within two miles of the plant since 2015. The plaintiffs seek to have the suit certified as a class-action case.

The complaint states that members of 80 households have told lawyers about odors they attribute to the plant, and that the class-action suit would represent more than 100 complainants.

Sanimax has faced similar lawsuits at facilities in Wisconsin and Montreal. Liddle and Dubin, a Detroit law firm that handled a Wisconsin case which Sanimax settled for $915,000, is assisting with the South St. Paul suit.

Odor long has been an issue in South St. Paul, a meatpacking center before its stockyards were closed in 2008.

The Sanimax plant, at 505 Hardman Av., is located near two slaughterhouses and a tanning business in the city's former stockyards area, now the industrial district. The companies together conducted an independent study in 2013 to identify and monitor odors in the area and shared their findings with the city.

In 2014, the City Council tagged Sanimax a "significant odor generator" and required the company to create and implement an odor-mitigation plan or face potential fines and restrictions.

Sanimax fought back in its suit last year against the city, arguing that the ordinance was too vague and that an olfactory device called the "Nasal Ranger" — used by the city to measure air quality — couldn't determine the source of the smells. Sanimax dropped the lawsuit when South St. Paul withdrew its designation of Sanimax as a significant odor generator.

South St. Paul City Administrator Steve King said there was an outpouring of comments on social media during the survey phase of the suit. "It is good to see the residents of the community are stepping forward on the issue and how it affects them," he said.

Trevor Squire is a University of Minnesota student on assignment for the Star Tribune.