The School District of Philadelphia doesn’t pay Scott Blunk to run the composting program at W.B. Saul High School in Roxborough, where he’s volunteered between 20 and 25 hours a week for the past eight years. But sometimes he reaps benefits in other ways.

The program uses produce scraps from area restaurants and grocery stores, including Weavers Way, Citizens Bank Park, the school cafeteria and more than 1,500 homes in the area—so sometimes more than just greens make their way into the compost. “I’ve found complete sets of silverware in here,” Blunk says as he pulls a large spoon from a pile of deep black compost. Latex gloves, rocks, and credit cards are also common finds. “Never found any cash, though,” Blunk laments.

When Blunk moved from Northern Illinois to Mt. Airy in 2010, he was a retired self-proclaimed “Earth guy” looking for a project. He had worked in agricultural engineering and sales and owned a tree farm in Southern Illinois and a restaurant in St. Louis, so he was accustomed to being busy and had mechanical and business savvy on top of his outdoorsiness. He started volunteering in Saul’s gardens, completing small projects around the farm—fixing a tractor, sharpening a chainsaw.

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But Blunk quickly noticed a disturbing fact: The School District was paying a third-party company to haul away the manure produced by the farm’s 35 dairy cows, and was then paying for mushroom soil from Kennett Square to tend the gardens on the land. In other words, the school was paying for the ingredients of compost to be removed, then paying again to purchase compost to be brought in. Blunk, the Earth guy that he is, thought, “Why don’t we just do this ourselves?”

“A pile of poo would be important anywhere. It would be important in the middle of Iowa,” says Blunk. “But in Philadelphia, you’ve got 575 kids across the street who can learn from it. That’s really valuable.”

A 1998 grant had afforded the school—the largest urban agricultural high school in the country—the equipment and site needed for a composting program. But no one had ever had the free time to implement it. Blunk, who had grown up on farms and had a thorough background in agriculture, had nothing but time. He had found his project, and he dove in full-steam-ahead.

When Blunk started, the composting site covered an acre of land, and more than half of it was taken up by a massive pile of cow poop that Blunk describes as being “as tall as a tree.” The manure was viewed as a hassle, rather than as an opportunity. Today, the composting program serves as a gift to the local environment, a teaching tool for Saul and a source of profit for the school. And, it seems, as a source of purpose for Blunk, who uses the word “poo” in every other sentence and stops a conversation to note that the wind has shifted, and so he and his companions can now better smell the manure on-site.

Blunk and the students who help him start each month by creating an “alpha pile,” which eventually towers over the people who work on it. They add poop from the farm’s cows, as well as from the Philadelphia Zoo’s herbivore and omnivore population, and food scraps from all over the city, including coffee husks from participating cafes. A relatively recent addition to the mix is spent grain from local breweries—also used as feed for the dairy cows—something easy to come by in a city like Philadelphia. In the alpha pile, you can differentiate compostable items—the “greens”—from the animal poop—the “browns,” as what Blunk calls “the ingredients” have yet to start breaking down and mixing together.

In addition to the alpha pile, several further along piles, each started in a different month and in a varying stage of completion, dominate the site. Blunk tills the piles frequently, thus speeding up the composting process, and after five months tests tests a pile for ammonia and CO2, then turns it into a “windrow,” a much shorter, longer, and darker pile that more closely resembles dirt than than the taller, younger piles do. The process takes approximately six months in total.

Blunk says even if they didn’t actively work the piles, it would still turn into compost, but more slowly. “It’s like if you put an apple on the dashboard of your car,” Blunk explains, “after four or five months there wouldn’t be much left.”

The whole thing is a ton of work, especially for someone who isn’t being paid—Blunk’s only income through the project is earned via picking up and delivering compost. But the work of the composting program provides huge benefits to the farm itself. “On a farm, the goal is to recover nutrients. Every time you remove a bail of hay, you’re removing nutrients,” explains Blunk. But if you then feed that hay to a cow, and use the cow’s waste to create compost that will fertilize new hay growth, you “keep the nutrients in the farm rather than letting them go into landfills and become methane.”

When Blunk started, the composting site covered an acre of land, and more than half of it was taken up by a massive pile of cow poop. Today, the composting program serves as a gift to the local environment, a teaching tool for Saul and a source of profit for the school.

The students benefit as well. “Instead of having something that’s just a pile of poo, we turned it into a laboratory,” says Blunk. Junior Brielle Stevens became involved in the program in her freshman year, and recently used money she earned screening and bagging compost on a Saturday to attend an agricultural competition at Penn State. “We learned the basics of where it came from, the proper mixtures of greens and browns, what temperature to keep it at, and how to turn it,” she says. She also engaged in small projects examining how long it took for different compostable products to decompose, including a lunch tray that eventually became the compostable tray the entire district uses in its cafeterias.

Cow poop isn’t the only living laboratory at Saul; the 130-acre campus has greenhouses, pastures, barns, and a farm store, operated by Weavers Way, where students work selling what is produced by the farm. The store, like seemingly everything else on the campus, is more than just a school project—it has become such a popular destination in Roxborough that parking can be hard to comeby by midday. The school boasts the largest Future Farmers of America chapter in Pennsylvania and prides itself on hands-on agricultural experience on a rural mecca smack-dab in the middle of the country’s sixth largest city.

Students major in animal science, horticulture, natural resource management, or food science and processing, and have access to specific real-life experiences in each field. Animal science students get jobs at the zoo, horticulture students work in the gardens, and so on. Recently, fields like aquaponics, or the symbiotic growth of water plants and animals, and the uses of agriculture in urban settings have popped onto student radars because of the specific passions of their teachers.

The composting program has opened up job opportunities for Saul students, too; in exchange for processing their food scraps and animal poop and thus helping them reduce their carbon footprint, the Phillies and the Philadelphia Zoo each reserve job slots for Saul students and, in the case of the Phillies, offer ticket freebies from time to time.

A 2.5 gallon bag of Saul’s compost retails for $5, though the school donates quite a bit of it to local nonprofits. The money covers the very minor upkeep costs at the farm, but any profits are poured into the nonprofit Saul Supporters, a fundraising organization for the school, or are used to fund summer internships for students or pay them when they work on weekends. “Brielle’s big hoop earrings are also paid for,” Blunk jokes of Steven’s staple wardrobe item.

Blunk’s involvement has allowed him to build relationships with the kids across the street at Saul High School, as is evidenced by his easy going relationship with Stevens. “We sometimes forget this, but it really is all about the kids,” he says. “A pile of poo would be important anywhere. It would be important in the middle of Iowa. But in Philadelphia, you’ve got 575 kids across the street who can learn from it. That’s really valuable.”