Residents and visitors might have been catching a waft of something abnormally smelly being emitted from Port Huron’s wastewater treatment plant downtown within the last couple of weeks.

City officials said they’re working on it — but that it's not an immediate public health concern.

“It’s just a nuisance," said City Manager James Freed. "I guess what I want people to know is we recognize it’s a problem."

Public Works Director Eric Witter said a perfect storm of challenges amid multi-phase plans to replace an odor-control system and malfunctioning mechanisms installed as part of a new one is allowing more smells than usual to escape.

And while they “don’t know exactly what the cause of the odor escapes are,” he said they’re investigating the issue, and in the next “two to four weeks, we might have some better answers based on the testing we’ve done and the equipment that’s being installed.”

“We still have the old system that is aging and has issues that we’re continuously dealing with. But … the new equipment, we’re working with the consultant engineer and contractor to get it to function where it should be,” Witter said Thursday. “… It’s really gotten to the point where the system should be functioning, it’s not, we’ve had some issues getting parts for the new system, getting those installed. We’re trying to get there this week.”

The city’s wastewater plant — first built on the edge of the St. Clair River in 1951 and upgraded two decades later — had its older odor control system installed in 2005.

City Council first OK’d a $2.2 million odor control system replacement, particularly for sludge storage tanks, at the plant in August 2020.

Now, exactly two years later, Witter said the equipment installed in that area isn’t “maximizing its efficiency,” though he admitted it’s difficult to explain how.

“We’re installing additional, we call them, modules. But it’s the things that the air’s pulled across and ionized,” he said. “We’re trying to get those fully installed.”

The old system pulls air through ductwork across much of the treatment plant’s fully enclosed facilities with a primary and backup fan that have also experienced failures or breakdowns within the last several years. According to past council documents, sodium hypochlorite and sodium hydroxide are the chemicals pumped into the system before odors are sterilized and vented out.

Unlike that system, the new one, being installed in three phases, will eventually control odor area by area versus more plantwide and with three different treatment technologies.

Phase one has been implemented and addressed just the one area, where biosolids or wastewater sludge is stored, while the old system remains in place to accommodate the rest of the plant.

Witter said it wasn’t clear why part of the new mechanism that scrubs the air of toxic chemicals wasn’t working.

But because the area with biosolids is one of the plant’s most odorous already, he said it may be more noticeable when it isn’t working.

They also must take it offline briefly to take and test samples as part of the repair process.

In an email to Freed, which he forward to council members on Monday, a plant official explained the air inside the biosolid storage tanks and at the exhaust is tested for different compounds, including ammonia, hydrogen sulfide, and amines, to determine how the system is functioning.

Freed asked public works officials via email about the status of reverting to the old air-handling system for the affected area. Witter later said he didn’t think it was needed yet, though possible, while they continued to fact-find.

As they take on remediation, Freed also said they're trying to be cognizant of the impact on the public, for example, in waiting for winds to shift if they're opening up storage tanks. "It's not every day," he said, "when there's a flare-up."

Still, both Freed and Witter said the city’s recently been getting more complaints than usual about the smells coming from the wastewater plant.

“It’s performing but not at the level it should be,” Freed said Wednesday. “So, we do have odor issues that are not normal, and we’re working hard on it.” 

Developer Larry Jones’ Wrigley Center project is being erected close to the plant, and he and wife Tracy also live nearby with a long loft patio that faces in its direction.

Like others, he said he’s heard about odor issues before, adding, “It is what it is. We have to deal with it,” because of the plant’s location of several decades.

It just hadn’t affected them yet — at least not until recently.

“People say things like that to me, and literally, I hardly ever notice it. But like last week, we had a wind out of the east,” Jones said Thursday. “I can’t say out of all the time me and Tracy lived up there that we’ve ever smelled it. … And it was kind of bad. But that’s one time out of several years.”

In addressing those concerns, Witter said they want residents to know they’re “trying everything we can.”

“Obviously, if it’s not satisfactory to us,” he said, “we’ll take necessary actions and make it correct.”

Contact the city’s public works department at (810) 984-9730.

Contact Jackie Smith at (810) 989-6270 or jssmith@gannett.com. Follow her on Twitter @Jackie20Smith.