[I]n late April, a faulty valve sent seven million gallons of partially treated wastewater into Lake Champlain. In early June, beleaguered bacteria were to blame for back-to-back releases that sent nearly two million gallons of partially treated wastewater and stormwater into the lake, closing area beaches. And last week, a computer malfunction sent three million gallons of mostly stormwater into the lake that had not been treated at all.
The city’s top priority after last week’s glitch is to upgrade the computer system that controls the treatment plant’s day-to-day operations, Megan Moir, city director of water resources, told a Public Works Commission meeting last Wednesday.
Describing the July 10 incident, Moir said the plant manager had turned on the pumps that release the disinfectant remotely, which is routine during periods of intense rain — referred to in the wastewater world as “wet weather flow.” But due to the computer malfunction, the disinfectant was not released from the pumps. An on-call employee went to the plant and manually turned on the disinfectant pumps, but not before millions of gallons of wet weather flow had poured into the lake untreated. Moir noted the release was about 95 percent stormwater.
In response to queries by public works commissioners, Moir said the releases did not affect the quality of drinking water in Burlington and the other towns that draw water from Lake Champlain. Moir said there had been no increase in chlorine demand — an indicator of a drinking water quality problem — at the city’s water treatment plant.
“From a drinking water quality perspective, I have no concerns,” she said.
For now, the plant’s computer system has been rewired to bypass the faulty component and the city is making arrangements to add staff when rain storms are in the forecast. The city has put out a bid to replace the entire computer system, Moir said.
The computer system is not all that needs an upgrade. Burlington’s public works department, which manages its wastewater treatment system, launched a multi-year planning process in 2016 to prepare for a major overhaul of the entire wastewater system. A capital upgrade plan for the wastewater system will go before the City Council in December, to be voted on at Town Meeting Day. The department will request money to replace collection pipes and upgrade the city’s three treatment plants.
Among the challenges facing Burlington’s overburdened system are the city’s burgeoning beer and cider industries, the waste from which has contributed to a nutrient imbalance that is upsetting the treatment plants solid-digesting microbes. The city has been working with producers to side stream or pre-treat wastewater from the beverage-making processes, public works department spokesperson Robert Goulding said in an email Thursday.
Moir said the city is looking into whether other industrial customers, such as Church Street restaurants, also may be overwhelming the city’s treatment plans. The city has been working with an outside consultant to “keep the bugs happy,” said Moir.
Like other cities around the country, Burlington used to dump raw sewage directly into nearby waterways— in this case, Lake Champlain, the Winooski River and Englesby Brook. In 1953, the city built its first wastewater treatment plant on the waterfront. Two smaller treatment plants were added in the 1960s.
Despite upgrades in the 1970s, Burlington beaches were routinely closed due to poor water quality from stormwater runoff and raw sewage, said Moir. An estimated 170 million gallons of untreated combined sewer overflows were being released each year during that time.
Burlington residents approved a $52 million bond in the 1990s to upgrade the treatment system. Rather than separating stormwater and wastewater, the city decided to keep the main treatment plant, which serves downtown Burlington, as a combined sewer system but to divert stormwater from the city’s other treatment plants.
Burlington has made strides in recent years to better manage its stormwater runoff — a problem anywhere there are impermeable surfaces like paved streets and parking lots. The city has repaved sidewalks with permeable materials, and installed rain gardens to slow the flow of runoff to the treatment plant and to local waterways. The city has reduced its sewer overflow outlets — the pipes that in times of heavy rainfall accommodate the excess untreated stormwater and sewage.
Although having separate pipes for stormwater and wastewater can reduce “acute” water quality problems, failing to treat stormwater runoff — which contains pollutants like pet waste, road salt and pesticides — can create a “chronic” pollution problem, Chapin Spencer, director of Burlington’s public works department, told the meeting.
Last year, storms involving heavy rainfall caused the release of from 500,000 to more than 1 million gallons of untreated sewage from Burlington’s outlet pipes, according to data from the DEC’s public alert notification system, mostly from an outlet by Pine Street that flows into the Barge Street Canal. On June 18 of this year, the Pine Street outlet sent 120,000 gallons of untreated sewage into the canal.
“We have made clear progress over multiple generations, but there is absolutely more to do,” said Moir, acknowledging during the meeting that “even one gallon” of untreated wastewater into the lake is unacceptable.
The wastewater treatment systems of Rutland and Montpelier, and in towns around the state, are designed to release untreated effluent into nearby rivers during storms. These routine events are classified by the DEC as “authorized wet weather CSO overflows.”
The two most recent discharges in Burlington have prompted an investigation by the state into what caused the incidents and whether enforcement actions will be taken, Jessica Bulova, head of the DEC’s wastewater management division, said in an interview Tuesday. “I think at this point everything’s on the table until we conclude the investigation.”
Bulova said the state will review Burlington’s upgrade plans to ensure the design will allow the city to meet permit requirements going forward. The state has separately been investigating the release of 500 gallons of sewage into wetlands near Oakledge.
