Stench in Harmar and Oakmont caused by work at Allegheny Valley Joint Sewage Authority plant

Mild weather and the company of family made for a pleasant Easter Sunday at Debbie Carlberg’s home in Oakmont, but it was not to last.

Soon, a sickening stench wafted half a mile across the Allegheny River from the Allegheny Valley Joint Sewage Authority treatment plant in Harmar, spoiling their outdoor dinner plans.

“When we sat down, it’s like they opened an exhaust,” said Carlberg, 71.

It’s hardly news to nearby residents that unpleasant smells occasionally emanate from the plant, which processes up to 5.5 million gallons of wastewater a day.

In recent weeks, however, residents have complained of a more intense odor reaching both sides of the river.

“It’s worse than it’s ever been,” Carlberg said. “Can you just imagine when it’s hot?”

Tim Kephart, the plant manager, attributes the smell to improvements being made as part of a projected $102 million expansion and overflow mitigation project.

“It is rather bitey at this time,” Kephart said. “We’re working at getting some kind of deodorant system up and running.”

In a stage of the project that will span the summer, waste manager contractor McCutcheon Enterprises is upgrading the plant’s anaerobic digester. Bacteria living in this equipment breaks down wastewater solids into a practical use, such as fertilizer or biogas.

With the anaerobic digester down, plant operators have switched to an open-top aerobic digester. That accounts for the smell, Kephart said.

The project can be traced back to a 2014 consent order with the Pennsylvania Department of Environmental Protection and Allegheny County Health Department, which required the treatment plant to eliminate overflows at pump stations.

The county Health Department is tasked with inspecting and monitoring sewage treatment plants, including an annual Compliance Evaluation Inspection and responding to complaints.

People can report odors suspected of coming from sewage facilities to the Health Department for further investigation.

The department also monitors for untreated sewage entering streams, river and lakes.

“When sewage overflows contaminate public spaces and waterways, there is a potential human exposure to these harmful pathogens, which poses a risk to public health,” Gardner said.

A week of heavy and prolonged rain reinforced the program’s necessity, according to Kephart. The steady downpours brought average daily flows at the plant from 3 million to 16 million gallons.

It’s unclear how much of that spilled into waterways.

In an ideal world, weather has no impact on wastewater flows. Those should remain in the stormwater system, though some authorities do handle both separately.

Aging pipelines in the nine communities the plant serves — Cheswick, Fox Chapel, Harmar, Hampton, Indiana Township, Richland, Springdale , Springdale Township and West Deer — present a different reality.

“In these older communities … there’s a lot of terra cotta pipes,” Kephart said. “Which means there’s a lot of joints and probably a lot of leakage.

“When we entered the consent order, we tried to bring a lot of that up.”

The Allegheny Valley Joint Sewage Authority is doing what it can to limit overflows by consolidating four pump stations into a new, more efficient one in Cheswick. It also is upping capacity to 8 million gallons a day through larger sewer lines.

New air scrubbers should help with, but not totally eliminate, the usual odor, according to Kephart.

“It’s the nature of a treatment plant,” Kephart said.

Smell to last all summer — at least

The full project is expected to wrap up next year — 16 months behind schedule. It’s also set to come in slightly over the original bid of $97 million.

Kephart partly attributes the delay and inflated costs to covid-related disruptions as well as rising interest rates.

At least for the summer, residents will have to put up with the foul odor.

Some simply shrug

But not everyone is as upset as Carlberg.

The smell has seeped into Riverview Jr.-Sr. High School, but Superintendent Neil English called it “more of a nuisance than a disruption.”

Corey Robert, who lives in a row of Harmar townhouses near the plant, said he’s hardly noticed any difference.

“I know this stinks,” Robert said, “but let’s keep it in perspective.”

Mike Wehrer, longtime Oakmont resident and owner of Mike’s Wife’s Bar and Grill, isn’t too worried, either.

“I can’t say it’s bothered me at all,” Wehrer said. “What are you going to do about the sewer?”