DES MOINES, Iowa (AP) — Des Moines officials will continue to monitor complaints about a putrid smell wafting from an animal rendering plant near downtown that triggered calls to an odor hotline and forced patio diners at a restaurant to move indoors.

A city inspector traced the stench to Darling International, a business that processes food industry byproducts by heating them, The Des Moines Register (http://dmreg.co/NEVTq4 ) reported.

The city received 14 calls Monday night, enough to trigger the city's first odor inspection in 10 years, said SuAnn Donovan of the city's inspections division.

"It's a putrid, dead animal smell," said Bruce Gerleman, who owns the downtown seafood restaurant Splash.

Gerleman also owns Jethro's BBQ in northwest Des Moines, where he said patio diners had to move indoors because of the smell.

"This is restaurant week, which is one of our busier weeks of the year. I had customers in from all over the metro area," Gerleman said. "They're all dressed up and they come downtown and walk out of the restaurant at 8:30 or 9 and they're hit by that smell and they say, 'What was that?'"

Donovan said inspectors go out and pinpoint what triggered the odor alert.

"They check the wind and weather report, get downwind of it and drive until they catch the scent, essentially backtrack it to the location of the emission," Donovan said.

Gerleman said the foul odors used to crop up in Des Moines a dozen or so times annually, but have vastly improved in the past two years. Monday's stench was the worst, he said.

A telephone call by The Associated Press to Darling International's headquarters in Irving, Texas, was not returned Wednesday. The company makes products for use in livestock and pet foods, as a source for renewable energy as well as hides for the leather industry.

Donovan told The Register that the company has taken several steps to regulate the smell in recent years through investments in new technology.

By Tuesday, some said the smell still lingered. Downtown worker Justin Wise compared the smell to eggs and turkey left inside a hot car.

"I was like, this is smelly," he said.

Donovan said if a high amount of complaints — more than 10 in six hours — triggers two more investigations of Darling International, the business would be required to submit an engineering plan on how it would contain the smell.

"In our opinion it was probably an anomaly that something happened beyond their control, so we will continue to work with them," Donovan said.

___

Information from: The Des Moines Register, http://www.desmoinesregister.com