[T]he city of Rutland released 9.7 million gallons of stormwater and wastewater into East and Otter creeks this week.
After 1.9 inches of rain fell over two hours Monday morning, all four of Rutland’s combined sewer system relief valves released untreated wet weather flow — known as “combined sewer overflows” or CSOs. Because there are no public beaches near the overflow outlets, the city does not have to conduct water quality tests following overflows.
Although the most recent Rutland overflows were the largest this year, the city has had combined sewer overflows on 15 days so far in 2018. The city funnels wastewater and stormwater into the same pipes, which, until the 1960s, flowed untreated into nearby bodies of water, said Jeff Wennberg, commissioner of public works for Rutland, in an interview Wednesday.
Although the tainted water is now treated at Rutland’s wastewater plant, relief valves open during periods of high rain to prevent wastewater from backing up into homes and streets. These combined sewer overflows send untreated water directly into the Lake Champlain tributaries.
“Rutland is typical of older municipalities in the upper Midwest and Northeast that developed wastewater and stormwater systems together back in the 1800s,” said Wennberg.
“That’s the infrastructure that we’re wrestling with now.”
Combined sewer overflows contain concentrations of fecal coliform and microorganisms like giardia in excess of water quality standards, according to a study published in the peer-reviewed journal Applied and Environmental Microbiology. These bacteria, which can cause gastrointestinal diseases, pose a public health risk for at least 48 hours following a combined sewer overflow.
“They are a major water pollution concern for the approximately 772 cities in the U.S. that have combined sewer systems,” the EPA says of combined sewer overflows.
Rutland has increased its treatment plant site to handle over 22.5 million gallons of flow a day, making it the largest wastewater treatment facility in Vermont. But the Rutland plant — like wastewater plants around the country — cannot treat large surges of stormwater in short periods of time.
“You get to a point, there’s no way you could build the plant big enough to handle the largest storms,” said Wennberg.
And with climate change, those storm surges are likely to get worse. The state’s climate data show that not only has overall precipitation increased in Vermont, but so has storm intensity in many parts of the state, including Rutland, since 1949. Those high flow events directly contribute to combined sewer systems woes, said Wennberg.
“This is not the amount of rain — this is about the intensity of rain,” said Wennberg.
“We could take two inches of rain a day forever and never have an overflow,” he noted. “You give me one inch of rain in 10 minutes, or 15 minutes or an hour for that matter, and all bets are off.”
Rain gardens and smart sewers
The city spent $5.2 million in 2011 to separate a portion of the stormwater and wastewater collection systems, however, complete separation would come with a roughly $150 million price tag, Wennberg said.
Even if Rutland could come up with that large sum of money to completely separate stormwater and sewer treatment, Wennberg is not convinced the city should do so. Rutland is 85 percent developed — posing a challenge for adequate stormwater pre-treatment, according to Wennberg. Untreated stormwater contains pollutants like pet waste, road salts and pesticides. Runoff from developed lands contributes the most per acre to phosphorus pollution in Lake Champlain.
“The water quality would actually get worse if we separated everything,” said Wennberg. “If (stormwater) were to go to the streams untreated, that would send more pollution to the streams than the overflows do.”
The latest enforcement action the city received from the state’s Department of Environmental Conservation provided a list of wastewater upgrades the city needs to choose from to reduce overflows. City officials had to submit a plan to the state of what projects they will install or risk fines for permit violations, said Wennberg.
Wennberg said that rather than asking taxpayers to fund another multi-million dollar project with an unknown impact on CSO reduction, he asked the state for a grant to study effectiveness of different upgrades. The city contracted engineering firm Weston and Sampson to develop a model of the city’s combined sewer system. Wennberg said the model is almost done — engineers have been tweaking it to make sure flow predictions match real life storms — and soon his department will begin testing how different solutions would reduce combined sewer overflow.
“There’s no silver bullet – this is so expensive and it’s going to take a long time,” Wennberg said.
Rutland will need to take a three-pronged approach to successfully reduce combined sewer overflows, said Wennberg. By pre-treating rainfall and snow melt on-site through “green infrastructure,” the city can minimize the amount of stormwater flooding into water bodies or overwhelming treatment plants. Examples of green infrastructure include rainwater collection, rain gardens and permeable pavement that allows water to filter into the ground. Rutland is constrained with limited space to implement these solutions, but Wennberg said he plans to treat stormwater in situ whenever possible because “this seems to be one of the best solutions for controlling the problem” of runoff.
Wennberg said he is perhaps most excited by opportunities to use technology “maximize storage within the existing system.” He has been looking to Cincinnati, which invested heavily in “smart sewers.” Cincinnati installed hundreds of sensors and gates and valves to redirect flows to areas with more storage capacity. The smart sewers are estimated to have saved the city tens of millions of dollars and to prevent 400 million gallons of overflows a year.
Once the city has modeled overflow reduction from potential investment, Wennberg plans to ask taxpayers first for less expensive investments in stormwater pre-treatment and technology to redirect flows. Then he will request money as needed for new “gray infrastructure,” such as pipes and underground storage tanks.
If all goes as planned, Wennberg hopes to eventually reduce combined sewer overflows to once every five years.
Steve Atocha, co-owner of Middlebury Mountaineer and founder of guide company Green Mountain Adventures, said he had not been aware of the Rutland overflows. Atocha added that he leads fishing trips in colder, higher elevation streams like the Neshobe and New Haven this time of year, so he has not been monitoring water quality in Otter Creek.
“It’s fairly dirty to begin with. Everything on the western slopes of the Greens runs into the Otter,” he said noting that the opacity and color of the water discourages swimming. Atocha said he had chalked that up to agricultural runoff, but wondered if combined sewer overflows could be a contributing factor as well.
“I would never eat a fish out of the Otter,” he added.
Public alerts of sewer overflows and other wastewater plant discharges have to be reported to the DEC within one hour of discovery.
