From May 30 into June 1, more than a million gallons of sewage and stormwater from the Vergennes sewer system flowed untreated from a pump station into Otter Creek.
The mix of human waste, household discharge and street runoff poured into the creek intermittently for 31 hours with no public notice until a day later, when town officials informed state regulators of the overflow.
The overflow was a consequence of the Vergennes sewer system design. Known as a combined sewer system, it uses the same treatment facility to treat waste water – all the water that goes down a drainpipe or toilet inside homes and businesses – as well as stormwater runoff. This means waste water mixes with stormwater going down storm drains in the streets, and all of that polluted water is then processed at the same municipal plant.
Sixteen municipalities in Vermont have combined sewer systems. And while the Vergennes overflow was exceptionally large, overflows that put sewage into the state’s rivers and lakes are a regular occurrence.
“Back in the day, in the '70s and early '80s, that was sort of the design engineering standard for constructing sewer systems, and as a result, older systems – those in the Northeast, those in the central part of the country, the upper Midwest, and even out in the Pacific Northwest – a lot of systems were built this way,” says Pete Laflamme, the director of Vermont’s Watershed Management Division within the Department of Environmental Conservation (DEC).
The systems are designed to overflow when there’s heavy rain. Events like the one in Vergennes are allowed by regulators. Despite the risk to public health and impacts on water quality, communities downstream from overflows are not actively notified, and most overflow reports never make it past an obscure page that is three links deep on the DEC’s website.
“We no longer build them that way because of the very problems that we’re seeing,” Laflamme says. “When there are intense duration rainstorm events, these combined sewer overflow points act as almost pressure relief valves on the system. And rather than these backing up into homes, into basements, or washing out the wastewater treatment facility, these periodic releases happen... like I said, sort of [as] a safety valve on the system, if you will.”
So far in 2015, more than 1.5 million gallons of sewage and stormwater have flowed into the state’s waterways in 15 authorized overflows. That’s more than 30 times the volume of water released in authorized overflows during the same period in 2014, when 42,622 gallons were released.
The overflows are a tiny portion of the overall volume of water treated by the state’s combined sewer systems, and wastewater plants in general make up just 3 percent of the state’s polluting phosphorus contribution to Lake Champlain. Still, the legal dumping of sewage into waterways upstream from swimming areas and boat launches raises questions.
“Is it acceptable for an upstream community to pollute their downstream neighbors?” asks James Ehlers, the executive director of Lake Champlain International and perhaps the state’s most vocal advocate on the issue. “No, I don’t think so. No more than you and I can take our trash and throw it over the fence into the neighbor’s yard because we don’t want to pay a collection fee.”
For Ehlers, these overflows are simply a matter of communities being unwilling to make needed investments to separate their sewer systems from stormwater systems or to at least expand the capacity of existing combined sewer systems to prevent overflows.
“I think we need to start with the mindset that it’s never acceptable for an upstream community to shift its cost to downstream communities,” he says. “If people can agree with that, then we can start working on a statewide solution for investment in infrastructure.”
State regulators, for their part, are on board. There’s been a quiet effort for years to eliminate combined sewer systems and reduce their overflows in the state. The state has made significant progress over the last quarter-century, Laflamme says.
In 1990, he said, there were about 171 combined sewer overflow points – those “safety valves” he mentions – across 27 different municipalities. Now Laflamme says there are 60 overflow points in the state across 16 municipalities.
“We have a policy in place, and we work through our permits to require communities to have plans to separate out the stormwater,” says David Mears, the commissioner of DEC. “But as you know, a major focus of our ongoing efforts to reduce the amounts of nutrients and sediment and excessive stormwater going into our streams is in some tension with the desire to separate stormwater out, so the two things have to work in tandem.”
Developed land – which includes all paved roads, parking lots and other impervious man-made surfaces – makes up 13.8 percent of the state’s phosphorus contribution to Lake Champlain, more than four times as much as wastewater facilities. And when they’re not overflowing, combined sewer systems are cleaning the dirty runoff from paved surfaces before it goes into local waterways.
While separating sewer systems reduces the risk of human waste ending up in waterways, communities risk doing more harm to Lake Champlain and other water bodies by introducing excess phosphorus to the water supply through street runoff. That pollution must be addressed in order for separate sewer systems to help Vermont’s water quality problems.
Efforts to reduce polluted stormwater from flowing into waterways mostly consist of slowing the water down. Retention ponds, wetlands and vegetated ditches allow the stormwater to seep into the ground during storms, instead of running directly into rivers and lakes, carrying pollution with it.
“I don’t know of any communities that are going to be in the position of having to construct entire new stormwater treatment systems, you know like a big plant,” Mears says. “But they are going to have to invest in all those smaller, site or community-based systems where they build retention ponds in association with parking lots and put in more green stormwater infrastructure like vegetated wetlands and ditches and so forth. So there are definitely costs associated with separating stormwater out. In addition to the changes to the sewer system, you then also have to deal with the now excessive amounts of stormwater.”
Whatever the solution – expanding capacity of a combined sewer system so it can handle heavier flows or separating the sewer system – improving water quality is costly. Officials say there isn’t much money at the local or state level to support the changes.
The state has no money to offer communities that want to upgrade their combined sewer systems, but it does enforce standards.
Any work done on combined sewer systems in Vermont must bring them towards the goal of being able to handle what’s known as a “design storm” with no overflows.
“It states that you can’t have these combined sewer overflows up to a storm of 2.5 inches over a 24 hour period and with a particular intensity of about 1.1 inches per hour, so in other words you design the system and you design the retrofits to the system to a particular storm," Laflamme says. "There’s always going to be an intensity storm in which major flooding is occurring and systems are completely overwhelmed. Well, we’re trying to lower the incidence, so you have to come up with a design storm.”
Those standards are about to get tighter, Laflamme says.
“We’re in the process of updating that CSO policy as well, where we’re going to be raising the bar, if you will, we’re going to be increasing the design storm that these systems have to be compliant with, both in terms of overall duration and frequency, but also the intensity values around that. So we’re doing that work and we’re also requiring additional green stormwater infrastructure” to reduce the total amount of water that comes into combined systems during rainstorms.
But even as the state works to increase systems’ tolerance for storm events, only about 30 of the 60 overflow points can handle the current design storm. When the standards get tighter that number will likely fall, and the state doesn’t have money to give municipalities for improvements.
“The cost falls to the municipality,” Laflamme says. “They’re able to – in some cases if there’s money available – take advantage of our state revolving loan fund moneys to borrow money to do the work, but in the end, the costs fall to the municipality, they fall to the user populations on these systems.”
That investment has been hard to come by. Many communities have sewer systems that date back to a surge of federal funding that came with the Clean Water Act in 1972 and have seen little investment since.
The cost of building wastewater treatment capacity has simply never been in the local budget, Ehlers says, and local communities aren’t faced with the costs associated with not making that investment.
“No town in Vermont exists as an island, except when it comes to pollution,” he says. “Because a pollution event in, say, Montpelier doesn’t impact the residents of Montpelier. It flows downstream and it’s Richmond and Waterbury and Williston and Essex and all these other communities that have to deal with that either knowingly or unknowingly.”