Missoula City Council members on Wednesday began hashing out the details of a plan—the first of its kind in the state—that calls for planting trees capable of soaking up harmful sewage byproducts.
"Rather than putting (effluent) in the river, let's put it in the ground and grow trees," says Missoula Chief Administrative Officer Bruce Bender, who's leading an effort to create a 130-acre poplar grove adjacent to the Missoula Wastewater Treatment Plant.
Missoula's wastewater plant sterilizes more than eight million gallons of sewage per day. But when effluent flows from the treatment plant into the Clark Fork River, phosphates and nitrates remain. Those byproducts feed algae, which consume oxygen and, ultimately, harm fish. That's where hybrid poplar trees come in. Just as algae thrive on wastewater byproducts, deciduous trees do, too.
With that in mind, Bender, drawing from a pilot project that's been in effect for two years, proposes pumping hundreds of thousands of gallons of liquid effluent annually onto the poplar grove.
"It would take approximately a half a million gallons of water during the summer season," Bender says. "That has an immediate impact on the Clark Fork River."
The project would cost the city $19,000 annually in addition to a one-time investment of $26,000. Bender sees it as a smart move as state regulators eye implementing more stringent caps on nutrients municipalities can pump into waterways.
"Rather than continually spend money on these very, very expensive technologies to continue to remove these nutrients, this to us looks like a better use," Bender says. "It has other benefits in the sense that we are basically growing a renewable resource that can be used for biomass generator systems."
The Colorado-based Hybrid Energy Group (HEG) has agreed to tend the poplar grove in exchange for the right to harvest mature trees for construction projects and biomass energy production. HEG Vice President Tom Platt says he sees the deal as a win-win.
"It would solve a number of different problems," Platt says.
A public hearing on the proposal is slated for Monday night's regular City Council meeting.