Waste not, want not - Essex Junction plant turns community water waste into a resource

3 min read
Essex Junction

Chelsea Mandigo didn’t plan on building a career in wastewater. But today, she leads Essex Junction’s water quality division.

“I fell into it,” she said, then laughed. “Most people do.”

It’s true that wastewater treatment plants have a reputation for being pungent. Still, they play an important role in maintaining the health of the community.

As the City’s water quality superintendent, Chelsea makes a positive impact on the environment every day. She also gets to engage the public on water quality issues and use her project management skills.

Part of Chelsea’s role is to be a responsible steward of taxpayer dollars. That includes keeping operational costs down. Treating all that used grey water and sewage requires a lot of energy.

The Essex Junction wastewater plant has been partnering with Efficiency Vermont since 2000. In the process, they’ve saved nearly 1,600 MWh in annual energy use. The upgrades also improve water quality, while reducing emissions and chemical inputs.

Why is wastewater treatment so energy-intensive?

Wastewater is pumped through several tanks to aerate and clean it. It’s an elaborate process that requires a significant amount of energy.

The Essex Junction facility captures all the grey water and sewage for Essex, Essex Junction, and Williston. It treats the used water until it is clean enough to swim and fish in.

Nationally, wastewater and drinking water systems account for two percent of the country’s overall energy use. The industry contributes 45 million tons of greenhouse gases annually.

Energy-efficient upgrades can reduce how hard wastewater systems work. The result? Reduced costs, emissions, and chemical inputs. Chelsea assisted the plant with a $15.3 million, four-year refurbishment project to;

  • right-size its equipment,
  • improve its filtration,
  • reduce wasted energy and use of potable water,
  • capture solar and geothermal energy,
  • and capture waste energy using an anaerobic digester.

The remaining solid waste is transported to farmers to fertilize grazing fields.

The project saved almost a thousand MWh — the equivalent of powering 90 homes each year. The initiative paid for itself in seven years. Various aspects of the project went on to receive many awards, including;

  • the American Council of Engineering Companies 2016 Grand Award,
  • the New England Water Environment Association 2017 Energy Management Achievement Award,
  • the 2018 Governor’s Award for Environmental Excellence,
  • and Efficiency Vermont’s 2021 Energy Leadership Award.

Chelsea has participated in several waste reduction initiatives since she became superintendent. The plant is also fine-tuning new valves that oxygenate wastewater only where needed. This reduces the need for energy-intensive blowers.

“The Essex Junction site has been a leader in using innovative systems and technologies,” said Pat Haller. Haller is an Energy Consultant with Efficiency Vermont who has worked with the plant for nearly a decade. “Their efforts promote iterative learning and drive policy change at the local, state, and regional levels.”

Statewide support, industry-specific knowledge

All told the plant is saving 1,600 MWh each year since working with Efficiency Vermont. Chelsea shares her annual capital plan with us, and we let her know if there are potential energy savings.

“Efficiency Vermont asks us what projects we have coming up. If there are any energy savings, then they’ll do the calculations, or we will send more info,” she said.

For other wastewater operators interested in reducing operational costs, she suggests reaching out.

“My account manager and energy consultant share what other wastewater facilities have done to reduce waste. If you’re about to go through a big replacement project, pull in Efficiency Vermont. It will absolutely save you money. ”

Chelsea Mandigo, Water Quality Superintendent, The City of Essex Junction Water Resource Recovery Facility