A greener operation: Missoula’s resource recovery finds unique ways to manage waste
Kevin Moriarty/Missoula Current
One chemical reaction at a time, Missoula's Resource Recovery Facility is giving waste new life and turning it into something valuable. From the wastewater treatment plant to Garden City Compost, the operation creates a greener Missoula by recycling waste into something new.
The massive composting site diverts thousands of tons of organic waste from the landfill each year. Tree limbs, food waste and even solid material extracted from the city's wastewater are turned into rich, fertile soil through the composting process.
Raw organic material becomes compost for gardening in 3 stages, and the entire process takes 3-4 months. First, “organics” are combined in a mixer. Things like leaves, tree limbs, un-treated lumber, food waste and treated solid waste from the wastewater facility are blended.
Once the organic mix is blended, it is transferred to a cooking bunker. This is the part of the process where the organic material begins to break down. Microorganisms within the mixture break down the organic material including the tough, woody bits.
“As long as those bacteria and microorganisms have air flowing in there, they'll start munching and eating and doing their job,” said Jason Duffin, who has spent 18 years in various positions at the facility and is now the manager at Garden City Compost.
The process generates extreme heat and when combined with summer temperatures, a pile of organic material can reach up to 180 degrees. In order to cool down the organic material and keep the microorganisms within from dying off, Duffin said the piles are cooled by air blown up from pipes below.
Each pile of organic material sits in the cooking bunker for five weeks at an average temperature of 113 degrees. During the “cooking” process, microorganisms work to break down the material and at the same time, hazardous bacteria like salmonella and fecal coliform are killed off.
The final act allows the organic mixture to cure for 60 to 90 days. The temperature of the mixture is cooling at this phase, but chemical reactions continue to occur, stabilizing the mixture and making it suitable for plants.
Duffin lifts a handful of cured compost to his nose, “that’s when we sell it to our customers, when its cured and it smells like dirt.”
The company produces four different products, each with their own use, including an enriched topsoil and a potting mix.
In 2021, Garden City Compost diverted 1,700 tons of food waste, 6,600 tons of woody/mixed organics and 2,200 tons of treated bio solids from the landfill. For a small fee, anyone can drop off organic waste at the facility and keep it out of the landfill. For example, a pick-up truck full of yard waste or lumber will cost you $7, while a bag of food waste will cost you $1.
“Anybody that wants to be sustainable can bring product here,” said Duffin.
Garden city compost also partners with the privately owned company, Missoula Compost, which brings in upwards of 1.3 million pounds of compostable waste to the facility every year from the community via curbside pickup.
Garden City Compost is keeping mass amounts of waste out of the landfill, while the wastewater treatment plant has helped grow an entire grove of trees.
In 2014, the Resource Recovery Facility planted 90,000 poplar trees on the property and has been watering them with treated wastewater ever since.
All of the wastewater from the city of Missoula comes through this plant. Water from sinks, toilets and bathtubs contain everything from human waste to oil, food scraps, soap and other chemicals.
Once treated, the water is dumped into the Clark Fork River. The EPA sets a limit on the amount of treated wastewater that can safely be dumped into the river. The treated water still contains elevated levels of nitrogen and phosphorus, which have the potential to cause algal blooms and disrupt the river ecosystem.
The treatment plant is currently well under the dumping limit set by the EPA, and it's putting some 1.3 million gallons of wastewater every day to good use by pumping it over to the poplar grove. The trees stand in neat rows and create a canopy that nearly blocks the sun from piercing through.
The poplar grove not only keeps excess nitrogen and phosphorus out of the Clark Fork, but the trees also sequester carbon. The entire poplar grove is estimated to be holding upwards of 5,000 tons of carbon in the woody tissues and roots of the trees.
The poplar trees have grown exceptionally well in the eight years since they were planted, and the grove is nearly ready for harvest. The original plan for the poplar trees was for them to be harvested and sold for use as wood products, but the current market for poplar has thwarted that plan.
Research is currently being done on what the best strategy will be moving forward with the poplar plantation.
”We’re going to put them to the best use possible, but it's kind of up in the air right now,” said Duffin.
The city’s Resource Recovery Facility is using innovative solutions to make Missoula a more sustainable city. The facility creates much of its own power through methane capture technology and a newly installed solar panel array.
When the solar array becomes operational at the end of the year, the Resource Recovery Facility will aim to generate nearly 45% of the power it uses.