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Fence of the future: Fence posts made of recycled plastic solve problems with trash

Good fences make good neighbors, and a new type of fence post being made in southeastern South Dakota is also good for the environment.

In a warehouse south of Lennox, South Dakota, machines are churning through 6,000 pounds of plastic waste per hour and turning it into round or square posts that can long outlive any cattle or horses they corral.

Sustainable Products is taking solid waste that would sit in a landfill for decades – or centuries – and turning it into something long lasting for the ranch.

“You bring trash to the landfill, and that is there forever,” said Avery Zahn, owner and president of the company and creator of the process for making the posts. “It’s the same concept.”

Instead of sitting in a trash heap, the waste material becomes a long-lasting anchor for livestock fences.

Inside the warehouse just off Interstate 29, a conveyor belt leading to a shredding machine has a lineup of trash: empty antifreeze containers, laundry soap bottles, dog food bags, even car bumpers.

Thirty minutes later, that trash becomes 4-inch round posts, 6-inch rounds, 2-by-4 boards or 2x6s.

Three months in to manufacturing posts, Sustainable Products had used 369,000 pounds of plastic and trash.

“That would have been in the landfill,” Zahn said.

The posts have 10 times the tensile strength of wood, Zahn said. And they won’t rot.

That was the selling point for Joy Nelson, owner of the Joy Ranch retreat center near Watertown, South Dakota. The ranch worked with Sustainable Products to replace posts outside its horse arena. The fence line sits on a drainage path, and the wooden posts suffered.

“They were always rotting out,” Nelson said. “We had this pen that was always a mess and always in disrepair.”

Zahn installed the fence last September. Now the corral is home to Mamie and Ole, two of the ranch’s Norwegian fjord horses. Ranch staff is happy to have a permanent solution to what was constant fencing work. They’re too busy for that, Nelson said, and ranchers can relate.

“I think it’s going to be a wave of the future for anybody that has cattle,” Nelson said.

The posts install just like wood. They can be cut with a normal saw. They take screws, staples or nails, too. But where wood expands and contracts with the heat and humidity, working staples out, they stay in place on a plastic post.

Sustainable Products started producing its first posts in mass quantities in late summer 2023. Now the company is spreading the word. It will have its first retail trade show booth at the Black Hills Stock Show in Rapid City Jan. 26 through Feb. 3.

The plastic posts sell for prices comparable to the wood version. Sustainable Products sells its 4-inch round posts for $25 apiece, right in the middle of $22.50 for wood and $27 for preservative-treated wood.

“We try to keep the price down for the end consumer,” Zahn said.

To do that, Sustainable Products must procure its plastic and metal scrap for free, he said, and he’s found plenty of places needed an outlet for their waste. An Iowa company that makes pet food bags brings its seconds – the bags that didn’t turn out quite right. It sends 40,000 pounds of plastic a day. Other waste comes from auto body repair shops, the state highway department and elsewhere.

“The trash is purely endless,” Zahn said.

A building under construction at the Lennox site will serve as a drop-off location where anyone will be able to bring their recyclables. It’s expected to be ready this spring.

Sustainable Products can use most any kind of plastic, numbers 1-7, including films that many recycling facilities reject because they get tied up in the machines.

“It’s 100% pure trash,” Zahn said.

The biggest requirements for the waste they use is that it contain no metal and no chemicals. Pesticide containers have to be cleaned.

Along with the shredded waste, the company adds two propitiatory ingredients – also waste products that would otherwise go to the landfill – to give the posts strength, stand up to UV damage and make them fire resistant. There are no added chemicals or resins.

Once the trash is shredded it goes into a machine where it’s heated and piped into molds.

“It’s all about the cooling, the heating and the mixture,” Zahn said.

Zahn has been working on the process for two years. It took a year to prefect the formula.

“It’s not just grinding plastic and pressing it together,” Zahn said.

The machines he uses are also landfill rescues, and the byproducts that come from the whole process are recycled as well. The gas put off by the process is trapped, filtered and used to heat up the shredded recyclables before they go into the post-making mold.

“We recapture all the emissions,” Zahn said.

Zahn plans to add more machines for a total of six and ramp up to processing 18,000 pounds of trash per hour, running around the clock. The current staff of eight would increase to 25 people or more.

Across the state on the Pine Ridge Indian Reservation, another shredding machine is being set up to supply more material for the east-side factory. Echaga, an economic development arm of the Oglala Sioux Tribe, is turning an unused building once intended for a recycling center into a densification plant. Waste from the reservation will be trucked to the building near Kyle, South Dakota, and shredded.

Echaga CEO Gary Ruse said it will be a big cost saver for the tribe, which hauls its trash 100 miles in some cases to a landfill 50 miles north of Oglala that’s filling quickly.

“It will save the tribe hundreds of thousands of dollars in transportation costs,” Ruse said.

The reservation creates 75 tons of trash a day, and the hope is to recycle 90% of that. The shredded material will then be trucked to the plant near Lennox and made into fence posts and lumber. Some of those posts and boards will be sent back to the reservation and sold.

Ruse hopes to work with U.S. Department of Agriculture programs to supply posts, especially in organic production where treated lumber can’t be used. For one, he’d like to use the posts in cross fencing for cattle on land the tribe enrolls in the Conservation Reserve and Enhancement Program.

“Instead of something that’s expensive, expensive, expensive, this will be an income-producing project for the tribe,” said Tally Plume, a consultant for Echaga. “It answers the problem of what you do with the solid waste problem that’s growing every year.”

“I think Avery is on to something with this design of forever fence posts,” Ruse added.

Zahn can see a future, expanding his project across the country, working with tribes in remote areas and small towns that don’t have nearby recycling facilities to build plants where waste is shredded then shipped to a central manufacturing plant. All it would take is 50 tons of waste a day, Zahn said.

“They can have a revenue stream versus a waste generator,” he said.

Horses are Zahn’s passion, and he keeps his on a ranch near Hill City in the Black Hills.

He knows about fencing issues.

He also knows about the headaches of disposing of plastic waste.

“Encountering problems and creating solutions on the farm is what led me into this,” Zahn said.

Before he started making fence posts, Zahn owned a company that put plastic liners in old utility pipes. Infra-Track used cured-in-place liners that were fed through the old pipes, expanded with steam then cured with a blast of cold air. There would always be excess liner at either end of the pipe that the company had to dispose of, and it was always a major expense to take it to the landfill.

Zahn sold the pipe company in 2020 and resolved to find a solution for waste plastic.

By turning that waste into fence posts he can use on his Hill City ranch, he’s solving another problem. He thinks his solution is one that many people can get behind, from companies and municipalities that deal with solid waste, to farmers and ranchers who want long lasting fences.

“We’re doing something good for humanity,” he said.

Janelle Atyeo is a small town South Dakota girl enjoying her work as regional editor of the Midwest Messenger and Tri-State Neighbor while raising kids and no-till vegetables in central Sioux Falls. 

Reprinted with permission


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