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Twenty miles southwest of Boise, long rows of rich, brown earth sit in sharp contrast to the baked desert land and farms stretching for miles in all directions.

Every day, tons of yard waste and kitchen scraps from thousands of Boise households are trucked to the city-owned Twenty Mile South Farm, where it is turned into high-grade compost over several months and eventually given back to residents. Residents don't have to pay anything to pick up the compost. The program is funded through the city's monthly fee of $18.64 per household, on average, which goes toward trash, recycling and compost pickup.  

The compost program has exceeded city staff’s expectations for collection and participation rates since its launch in June 2017. The composting facility, built to accept 90 to 95 tons per day, receives more than 112 tons per day on average, Boise's Solid Waste Environmental Program Manager Catherine Chertudi said. 

“The citizens have embraced it beyond belief, and the material we’re producing is top-notch,” she said. “I’m just so proud of everybody involved, including every citizen and everyone on city staff. Every time I walk out there, I want to do a little dance because it’s pretty cool.”

All Boise residents are able to collect compost at their homes in designated carts, which are collected weekly with trash. All vegetative materials are accepted, such as table scraps, unused produce, yard waste, Christmas trees, fruit pits, coffee grounds and eggshells. Items such as dairy, meat products, animal bones and plastic materials are not permitted.

According to Chertudi, the city launched the composting program after an Ada County landfill study in 2014 revealed that over 45 percent of the Boise’s trash was compostable.

“It was sort of an ah-hah moment," she said. “Why would we want to continue being wasteful when we realized we have an opportunity to remove that waste stream for a good purpose?”

Since the program began, 27,922 tons of material has been composted by the city that would have otherwise headed to the Ada County Landfill, Chertudi said. Collections varied widely depending on weather, with February 2018 seeing the lowest of an average of 11 pounds per participating house collected, down from a high of 214 pounds per house collected in November 2017.

Since the program began, the city has given away 1,350 cubic yards of compost, sold 1,500 cubic yards to private businesses and used another 5,200 on city parks and other properties. Colin Hickman, city spokesman, said there has been more than enough materials for residents and interested businesses to pick up in the first year. The amount of material coming in to be composted has been so high that Hickman said the city is evaluating the site to see if there is a need for more space to produce compost. 

At the farm, staff sifts through the collections to remove non-compostable material, and then run what's left through an industrial-grade shredder. The compost is then sorted into 8-foot-tall piles.

While the material sits in the piles for roughly two months, staff checks oxygen, ammonia and moisture levels to make sure the material is breaking down into dense compost for gardening. During the process, the material reaches temperatures between 131 and 160 degrees in order to break down any bacteria or other pathogens.

“We are constantly watering the piles and checking for temperature,” said Steven Bills, Twenty Mile South Farm composting facility operations manager, while observing one of the more than 20 piles being slowly turned by a large machine. “You have to have enough oxygen in the material to keep the temperature high or the process stops working properly.”

Because this fund is an enterprise fund, all of the program costs are paid for with user fees. According to city spokesman Colin Hickman, all of the composting program's costs are covered by the fees collected. 

After the material has cooked in the piles long enough, it's moved to a curing pile for 20 to 30 days before being screened one more time to remove large chunks of material that did not totally break down. From there, it is ready to return to the public.

Boise residents who participate in the program can go to the Idaho Botanical Garden between 9 a.m. and 7 p.m. any day of the week to pick up 1 cubic yard of compost free of charge. There will be another compost pick-up station opening at the city’s West Boise Water Renewal facility this fall. This facility will need to be approved by the city's Planning & Zoning Commission later this month to be constructed.

Hickman said the city is also exploring the option of working with neighborhood associations to deliver large amounts of compost to areas where residents are interested in using it. 

In addition to giving the material back to participants, the city also sells the compost to local companies and uses it on city properties for landscaping and gardening projects. Cloverdale Nursery and Turf in Boise first purchased a small amount of the compost to test when the program first launched, but after seeing the high-quality of the material, they have since purchased "a couple thousand yards" of the city made compost.

“You’ve got to be skeptical of some of those things going in because it takes a lot of know-how to get that done right, but after going there and reviewing their operation and their process, we saw they have everything in place to make it what we needed,” Cloverdale yard manager James Kidd said.

Chertudi said the material goes through several rounds of testing before it is given to residents or sold to companies. These tests check for levels of bacteria, carbon, nitrogen and other chemical compounds. A lab in California also evaluates each batch of compost for how well cucumber seeds grown in it germinate and the health of the growth.

“We are really proud of the material we are producing for our residents,” Chertudi said.

Margaret Carmel covers the city of Boise. Follow her on Twitter @mlcarmel or reach her by phone at 757-705-8066. 

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