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Group pitches decentralized sewage network

The Deer Island Sewage Treatment Plant processes about 350 million gallons of wastewater a day.
The Deer Island Sewage Treatment Plant processes about 350 million gallons of wastewater a day.(globe file 2000)

The massive Deer Island Sewage Treatment Plant was once hailed as an environmental victory, one that would revive a then-defiled Boston Harbor while processing sewage for more than 40 cities and towns. But roughly 15 years after the plant's completion, one local group still isn't ready to celebrate.

The Charles River Watershed Association has instead proposed an unusual alternative to the hulking plant: smaller, neighborhood treatment centers that would convert waste water and discarded food into energy. That energy would then be sold to help defray the cost of the projects.

The nonprofit group's primary aim in developing the concept was to limit the vast amounts of rainwater and ground water that get sucked into sewer pipes to be washed out to sea via Deer Island, a phenomenon that is harming the Charles River by decreasing its water volume.

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"We cleaned up Boston Harbor but we're dewatering Eastern Massachusetts," said Bob Zimmerman, the group's executive director. "You tell me which is worse."

But protecting area rivers is only one of several possible environmental benefits. The effort could also bring more renewable energy into the area and restore now-buried waterways.

Zimmerman said none of the technology needed to make this happen is new. What is novel, he said, is the use of these technologies to break up a centralized sewer system and pair it with food waste processing.

These plants would first need to attract customers. Some of their business would come from the Boston Water and Sewer Commission, which would redirect some of its waste water to the facilities to be processed. More income would come from a food processing business that would rely on large customers such as colleges, hospitals, and big restaurants to ship discarded food to the facilities.

Like the waste-water residue, the food trash can be placed in an anaerobic digester system that breaks down the organic material and converts it to methane gas to generate electricity. That power could reduce a facility's operating costs and be sold into the region's grid. The remnants could be converted into fertilizers.

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"We're throwing away a lot of potential revenue as if it were waste, as if it were a bad thing," Zimmerman said. "It's only waste water if you waste it."

His group hired Natural Systems Utilities, a New Jersey engineering firm, to draw up conceptual plans and analyze the possible revenue for two potential plants: one in Boston's Mission Hill neighborhood and the other in the Widett Circle area between South Boston and the Southeast Expressway.

The Widett Circle proposal, for example, would cost $47 million to build, with $7.4 million in projected annual revenue, separate from sewer fees. That revenue would more than offset the nearly $5 million in anticipated operating and maintenance costs.

The next step: Finding a nonprofit or public-agency partner to finance and build a test project and prove that the concept can translate from a PowerPoint presentation to the real world. For now, the effort is being largely funded by a $650,000 grant from the Scherman Foundation's Rosin Fund. Mike Pratt, the president of the New York-based foundation, said his group sees the Charles River Association's concept as something that could be replicated in other metro areas.

But foundation money only goes so far. Zimmerman said his group is in talks with a local community development corporation. He hopes state environmental funds could be tapped to help his potential partner finance construction.

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Financing isn't the only potential obstacle.

Zimmerman and his team will need to overcome any skepticism from state and city officials and diffuse any opposition from neighbors. Zimmerman estimates he'll need roughly two acres for each facility but ideally would want more land to help construct a waterway that could carry treated water out to a river or the harbor. Any location would ideally have industrial properties nearby so thermal energy or cooling water could easily be shipped by pipe to a nearby customer.

Zimmerman will also need to win over the Massachusetts Water Resources Authority, the public agency that runs the Deer Island plant. The agency sends a representative to task force meetings held to discuss the idea but is taking a neutral position for now.

"The concept that the watershed association is studying and pursuing is interesting," said Frederick Laskey, the agency's executive director. "I think we're going to watch the results very closely. ... It's interesting stuff that they're looking at. Whether it works in its entirety, time will tell."

Could these neighborhood plants encroach on Deer Island's business? It would take more than a few of them to make a dent. Deer Island processes roughly 350 million gallons of waste water a day, according to an MWRA spokeswoman, while one of these neighborhood plants would process only 1 to 5 million.

Deer Island already generates some electricity from its 12 egg-shaped anaerobic digesters, enough for about one-fifth of the facility's on-site energy needs.

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But Zimmerman said Deer Island's isolated location makes it essentially impossible to sell thermal heat or cooling water to generate additional revenue, because potential customers would be too far away.

"There's so much found money [in a dense urban area]," Zimmerman said. "You're generating thermal heating and cooling for surrounding buildings. You're capturing food waste and converting that to energy."

Matthew Kiefer, a land-use lawyer at Goulston & Storrs in Boston, said the watershed group's proposal could be a creative way to address the problem of ground-water infiltration into the region's sewer system. But he said state and local environmental officials would likely need to draw up new rules for these facilities, in part to ensure that adequate backup measures are in place to prevent the release of untreated waste water.

"It seems to me it's an idea worth exploring," Kiefer said. "[But] I would think regulators would want to make sure these issues are addressed."


Jon Chesto can be reached at jon.chesto@globe.com. Follow him on Twitter @jonchesto.