In 1990, Waupaca Foundry supplied 20,000 tons of used sand for a Wisconsin highway pilot project. 12 years later, its next contract called for 80,000 tons for Highway 10

A Wisconsin highway project helped turn an industrial leftover into a useful construction material. In 1990, Waupaca Foundry supplied about 20,000 tons of used foundry sand for a highway pilot project. Engineers wanted to see whether the material could work as fill instead of relying entirely on newly sourced material.

The experiment did not end with that first project. Twelve years later, Waupaca Foundry received a much larger contract tied to Highway 10 near Waupaca, Wisconsin. This time, the project called for 80,000 tons of foundry sand for highway construction.

The increase was significant. The amount was roughly four times the volume used in the earlier pilot. It showed how testing could move an industrial byproduct from a small demonstration toward large-scale infrastructure use.


Foundries use sand to create molds for metal castings. After repeated use, some of that sand is no longer suitable for the casting process. Instead of treating all of it as waste, engineers began examining whether its physical properties could make it useful elsewhere.

The Wisconsin projects became part of a broader effort to find beneficial uses for spent foundry sand. Today, certain foundry sands can be used in applications such as structural fill and road construction when they meet environmental and engineering requirements. The story is less about replacing every load of conventional road material. It is about finding another job for material that might otherwise be discarded.

What made foundry sand useful for a highway?

The name can make the material sound more unusual than it is. Foundries use large quantities of sand to create molds and cores around molten metal. The sand is reused repeatedly inside the manufacturing process, but eventually enough of it changes that it can no longer perform properly for casting and becomes “spent foundry sand.”

At Waupaca, the material had another useful characteristic. An EPA review found that the foundry's sand was relatively uniform and similar to virgin sand, although it was finer, smoother and darker because of its industrial history. Its physical properties made it suitable for structural fill, including highway embankments, where enormous quantities of material are needed simply to build and shape the ground beneath a road.

That distinction matters. The sand was not being turned into the driving surface of Highway 10. It was being used as structural fill for the embankment, essentially helping create the engineered mass of material that supports the roadway above it. EPA records describe the material as performing comparably with fresh borrow or fill material in this application.

Why did Wisconsin test it first?

The road project did not appear out of nowhere. Waupaca Foundry's interest in reuse began in the mid-1980s, when it participated in University of Wisconsin-Madison research examining whether foundry sand could be used in highway construction. Researchers from Waupaca and two other foundries evaluated potential environmental concerns, including contaminants that might appear in pore water or leachate.

That research eventually moved from the laboratory and testing phase into a Wisconsin Department of Transportation pilot project in 1990. Waupaca supplied between 15,000 and 20,000 tons of sand, providing engineers with an opportunity to evaluate the material in an actual highway setting rather than only through controlled testing.

The next major step came with Highway 10 near the city of Waupaca. According to the EPA case study, Waupaca's contract called for 80,000 tons of sand for embankment construction, roughly four times the upper end of the 1990 pilot volume. For 10 months beginning in 2001, the company's foundry sand was hauled to a temporary staging area near the future highway site ahead of construction planned for summer 2002.

How was the material kept under control?

The environmental safeguards are an important part of the story because “recycled” does not automatically mean “safe.” The sand had to meet Wisconsin's requirements for beneficial use, and the Highway 10 project included monitoring designed to detect material moving through the embankment.

EPA records say lysimeters were used to monitor fluid leaving the fill. If measurements exceeded Wisconsin Department of Natural Resources requirements, Waupaca was required to investigate the cause, analyze the collected fluid and propose a response. The highway embankment was also to receive a clay cap, while the sand itself did not require additional treatment before use in the project.

Wisconsin's broader approach has since become more formalized. Chapter NR 538, first enacted in 1997, provides the state's regulatory framework for beneficially using industrial byproducts, including ferrous, steel and aluminum foundry excess system sand. Generators must characterize materials and compare their properties with applicable standards before participating in the program.

Was this just a Wisconsin experiment?

The idea eventually became part of a much broader American conversation about industrial materials. The U.S. Environmental Protection Agency now recognizes beneficial uses for certain silica-based spent foundry sands from iron, steel and aluminum foundries, including use as a foundation layer in road construction. EPA's assessment found that the evaluated materials and uses could be protective of human health and the environment when properly managed.

The potential attraction is straightforward. Every ton of suitable recycled material used in construction can replace some amount of newly mined material and avoid sending that material to a landfill. EPA says about 2.6 million tons of spent foundry sand are beneficially used outside foundries each year, although the agency also sees room for considerably more reuse.

That does not mean every pile of foundry sand belongs beneath a road. The EPA's findings are limited to specific types of sand and specific applications, and states still regulate how these materials can be used. Wisconsin's rules likewise require characterization and compliance with applicable standards rather than treating all industrial sand as interchangeable.

The Highway 10 project became one example of a much longer reuse story around Waupaca. The company has since used foundry sand in other construction and reclamation projects, including mine and gravel-pit restoration. Waupaca Foundry says hundreds of thousands of tons of its byproducts have been used to help restore inactive mining sites in Wisconsin and elsewhere.

The company's own later projects also show how far the idea traveled locally. Foundry byproducts were used in the construction of Waupaca's Swan Park, including a 42-foot sledding hill, while thousands of tons of foundry sand were also used for the community's Eco Park.

The most revealing part of the Highway 10 story, though, is the progression from experiment to infrastructure. In 1990, engineers were asking whether spent foundry sand could work. By 2002, they were planning around 80,000 tons of it. That history offers a useful lesson for the rest of the United States: some industrial waste problems are not solved by simply finding a better landfill, but by figuring out whether the material still has a job to do.