BRATTLEBORO — Toward the end of last summer, the Department of Public Works asked residents, while they were out and about, to breathe deeply.
And the DPW further asked, if they smelled the particular methane-and-hydrogen-sulfide aromas that scream “sewer,” to call and report their location.
Up until a few years ago, the department received numerous complaints of a sewer smell in a few locations around town.
After the town's Waste Water Treatment Plant operators made some changes to its procedures, the odor - and the complaints - stopped. But Public Works Director Steve Barrett wanted to make sure.
In August, the Selectboard approved a $39,910 engineering contract with Bowker & Associates to study odor control at the plant.
The DPW recently received the results of the Bowker study, which confirmed what the plant's operators already knew and gave the town some valuable advice.
As Barrett told the Board in August, “the goal here is to keep our odors to ourselves within the confines of the plant.”
Helping nature's process
The Waste Water Treatment Plant first went online in 1967. For 3,400 customers, the plant each day treats approximately 1.5 million gallons of wastewater that travels through 50 miles of sewer lines connecting the sinks, tubs, toilets, and washers to the Riverside Drive facility.
Through a process of separation, digestion, and chlorination, the wastewater that comes in leaves in a much cleaner state. The effluent safely ends up in the Connecticut River.
Bruce Lawrence, the plant's chief operator, likened the system to how nature handles wastewater - except at the plant, everything happens much faster, he said.
“We are cleaning up the water to as clean as, or cleaner, than the river,” he noted.
In part, the DPW contracted with Bowker because of the changing nature of population density around wastewater treatment plants.
In August, Barrett noted plants nationwide, including Brattleboro's, are generally sited in “more desolate areas.” But, with residential, recreational, and business development starting to move closer to plants, “it ups the ante” to make the plants less smelly.
The plant, located off Vernon Road in a marshy area alongside the river, has Triple T Trucking's transfer station - where trash and recyclables are collected and sorted - as a neighbor, along with the Morningside condominium complex and other standalone homes.
A controlled experiment
Until a few years ago, the DPW received complaints about the “sewer smell.”
Many were reported from farther north on Putney Road, about 3 miles from the plant, where gases released from the wastewater treatment ended up after having travelled along the surface of the Connecticut River.
To manage this, the plant's employees implemented an internal odor-suppression system, “and it's been very successful,” said Barrett, who praised Lawrence and his staff for their work. “The number of complaints has virtually dropped off,” since the plant's workers made the change.
But did the odor-suppression system really work? That's what Bowker & Associates was hired to find out.
To answer the question, the plant's operators disabled the system for one week, but otherwise ran the plant as usual, from Aug. 20 through Aug. 27.
At the time, Barrett warned the Selectboard, “The public may experience some odors. If they do, we want to hear about it. Please call us and let us know.”
Meanwhile, Bowker tested the air at the facility and entered data about weather conditions, like wind speed and direction, into a computer program to create a model to predict where the odors might be detected.
The DPW “already has a good idea” of the answer, said Barrett, because staff had documented public complaints from the three or four years prior to the odor-suppression system. The study's results would allow them to compare the two data sets.
No stink?
Lawrence said that even with taking the odor-control offline for the study, “the problem hadn't recurred.”
Still, Bowker collected 10 liters of samples from the air at the plant and from the top of the liquids floating in the plant's various tanks.
According to the report from Bowker & Associates, which Lawrence shared with The Commons, the air samples “were sent by overnight carrier to St. Croix Sensory in Stillwater, Minn., for determination of odor concentration.”
In accordance with European and other international standards, a panel of six trained odor-detectors tested the samples.
“Actual people sniff it,” said Lawrence.
Bowker's results, said Lawrence, “backed up the same conclusions we made. The numbers matched up with experience.”
A change in the procedure
Another change the plant's staff made a few years ago, which helped the odors, was in the way it processed the solid materials that come in directly from everyone's sinks, showers, washers, and toilets.
The facility was initially designed as a two-phase anaerobic digestion plant. The raw sludge got heated and held at 140 degrees Fahrenheit, then the temperature is reduced to 96 degrees for a longer period of time.
This kills any pathogens present in the material, and produces Class A biosolids, which are “more fit for general usage,” like compost for flowers, said Lawrence.
Now, said Lawrence, the plant produces Class B biosolids, which must be trucked off-site for the final step to turn them to Class A biosolids. (“We are not landfilling any of our solids,” he asserted.)
The change came about, he said, because the computer that managed the temperature and hold time “was a pain in the butt.”
In 2014, the DPW kept getting odor complaints from people on Putney Road, South Main Street, Morningside, and Route 119, said Lawrence.
“The system kept breaking, so we decided to run the plant for Class B sludge,” Lawrence said.
That meant skipping the 140-degrees step and going right to the 96 degrees, to see if that change would help, Lawrence said.
It did.
“The pretty bad odors went away overnight,” he said.
“We would still get an occasional complaint,” Lawrence noted. “After doing some internal studies, we added an atomizing perfume to the air. The chemical supply company gave us a hydrogen sulfide neutralizer, and the complaints totally stopped.”
So, have there been odor complaints since the completion of the Bowker study?
“I refuse to answer that on the grounds that it would probably jinx me!” Lawrence said, laughing.
After a brief pause, he said, more seriously: “The short answer is, no.”
Helpful advice
Even though the study showed what town personnel had suspected all along - that the plant's staff solved the odor problem a few years ago - Lawrence said, “I think the money was well-spent.”
Bowker also provided some advice for eliminating even more odors, he said.
“He told us to put a cover on the open-sludge tank, which is a big-ticket item. We'd have to get an engineer and issue a request for proposals,” said Lawrence.
Other Bowker-issued recommendations include adding odor-neutralizing chemicals twice: once at the plant's headworks, and again halfway through the system.
Lawrence pointed out that his plant is technically not funded by taxpayer dollars, and that includes the money for the Bowker & Associates survey.
Funding for all aspects of operations of the town's drinking-and-wastewater systems, including staff salaries, come from the town utilities fund, which collects revenues from the 3,400 customers in the system.
Even though most of the customers are likely also property owners paying property taxes, the funding is separate.
“It's not part of your tax bill,” said Lawrence.
Brattleboro's wastewater treatment plant has to meet or exceed state and federal standards, especially in the quality of the treated water - the effluent - that is released into the Connecticut River.
“Our mandated regulation is 77 colonies of E. coli per hundred [milliliters of water]. The state doesn't consider water unswimmable until around 270 colonies per hundred.
“In that way, we are cleaner than the river,” said Lawrence.
The reason E. coli is used as the standard, he said, is “it's easy to sample and harder to kill. If you kill the majority of the E. coli, you're killing most of the [other] bacteria.”
“So far, this year, we've only had one E. coli violation,” said Lawrence. At that point, the plant's operators had to report their findings to the state, then collect and analyze a second sample.
The first sample, the one that failed the standards, showed 2,000 colonies per hundred milliliters. “Twenty-four hours later,” said Lawrence, “the second sample showed 20 colonies, well below the limit.”
“More times than not, our E. Coli count comes back undetectable, or in the single digits.”
The likely culprit on the violation day was “chlorine problems,” said Lawrence. “We didn't add enough.”
Stop flushing 'those wipes'
When asked if there's anything he wants Brattleboro residents and visitors to know about wastewater, Lawrence - who comes across as friendly and mild-mannered - nearly jumped out of his seat.
“Stop flushing those 'flushable' wipes!” he said.
“Those wipes,” a clearly vexed Lawrence said, are not really flushable, regardless of what the package might say. He urges people to throw them in the trash instead.
That's because even if wipes “flush out of your house easily, they get stuck in the pump. And they build up.”
They then cause pipes to back up or a pump to fail. Sometimes the havoc they wreak is in your home plumbing, or they cause problems farther down in the municipal system.
“They don't break down like toilet paper. They're probably one of the worst things ever, as far as wastewater treatment, that's been invented,” said Lawrence, who described so-called flushable wipes a “municipal nightmare.”
Lawrence insisted that the plant's smooth operation and success with eliminating odors and meeting or exceeding governmental and industry standards “is not me. It's the crew.”
He characterized his crew - Harvey Dix, Steve Dyer, Mike Ethier, and Gary Corey - as “excellent.”
“I don't have to tell them what to do or worry that they're doing it,” Lawrence said. “They know what they need to do.”