HAVERHILL — The stench is finally gone.
For years, foul odors coming from the sewage treatment plant in Bradford during the summer triggered complaints from neighbors of the plant and residents across the river.
But the complaints, which totaled 10 to 15 per week in past years, have dwindled to zero this summer, city officials said. It's all thanks to installation of new odor control technology, they said.
Mayor James Fiorentini toured the plant on South Porter Street last week to learn more about the technology. He viewed the equipment that has brought a major reduction in the nasty, sewage-smelling odors of past years.
Plant manager Isaiah Lewis escorted the mayor on the tour.
"The last time I was here it stunk," Fiorentini told Lewis. "I don't smell anything now."
The mayor said the improvements in odor control will help boost property values in the immediate neighborhood and all along the Merrimack River.
"We've improved the quality of life for anybody within smelling distance of the plant, which isn't just in Bradford," Fiorentini said.
Deputy Public Works Director Robert Ward said the new system, which became active about two months ago, draws odorous air from the plant's main process building, the sludge processing areas and outdoor covered channels and delivers the air to a biofilter that removes the odors.
"This was by far the biggest piece of reducing odors at the plant," Ward said. "This project that we've just finished has taken care of the most odorous areas we have."
Not only is the reduction in odors a benefit to neighbors, he said — workers at the plant benefit too.
"It makes the plant a much more pleasant place to work,'' Ward said. "We used to have odors in the plant and processing areas, as well as in the administration area.''
The project also includes a new carbon filter system to eliminate odors from the South Mill Street pumping station. The $5.6 million project was funded by a low-interest loan from the Massachusetts Department of Environmental Protection, city officials said.
"Since the systems have started, we have not received any odor complaints," Ward said.
Beginning in the summer of 2015, the city and its consultant, Woodard & Curran, began sampling odor emissions at the plant to identify significant problem areas.
The city completed the first phase of the plan two years ago, which included adding covers and ventilation on open influent conveyance channels — concrete channels where sewage flows into the plant. The channels had been exposed to the air and have since been covered. In addition, the odorous air is channeled through a biofilter.
Ward said such filters biologically treat the air to reduce compounds that cause odors. An activated carbon odor control unit was installed at the main sewage pumping station on South Mill Street as well.