A Cleveland Factory Processed Uranium for the Manhattan Project. It's Still Being Cleaned Up.

“A short time ago, an American airplane dropped one bomb on Hiroshima, and destroyed its usefulness to the enemy,” President Harry Truman said in a measured tone on Aug. 6, 1945. “That bomb has more power than 20,000 tons of TNT.”

Hours earlier, the “Little Boy” bomb was dropped on Hiroshima, Japan. Three days later, the “Fat Man” would drop on Nagasaki. The ground reached more than 3,000 degrees Celsius in the instant of detonations. Two towns’ buildings, homes, roads, bridges and people were wiped from existence. Ghostly shadows remained of human beings on concrete and bricks. Between 110,000 and 210,000 people perished, the Bulletin of the Atomic Scientists estimates.

It was incomparable destruction, unlike any moment ever witnessed in warfare.

“It is an atomic bomb,” Truman calmly said to the world, to the United States, to Ohio, to Cleveland. “It is a harnessing of the basic power of the universe.”

Most Americans learned of the country’s nuclear weapons development for the first time after this event. That even included many workers at Harshaw Chemical Co., who might not have known they contributed to the project for years.

Here, on a crook of the Cuyahoga River in Cleveland, Harshaw’s Harvard-Denison factory once made extraordinary contributions to the Manhattan Project, the United States’ program to develop the first atomic bomb in the 1940s. Workers there helmed a chemical process used in uranium processing and shipped thousands of tons of radioactive uranium hexafluoride out of the city.

“That’s the one thing that makes the Harshaw story incredibly important,” says John Grabowski, editor of the Encyclopedia of Cleveland History, “because in this case, people were war workers, but they weren’t aware exactly where (the materials) were going.”

On the Harvard-Denison bridge, you can stand over what used to be Cleveland’s uranium processing center. Now, it’s a mostly barren, 55-acre expanse of industrial land, crisscrossed by train tracks near the Cuyahoga River and Cleveland-Cliffs’ operations.

Some call this the most toxic site in Cleveland. In Google results, you’ll find widgets of yellow-and-green toxic barrel symbols in blog thumbnails. One of those blogs contains detailed instructions for out-of-towners to see it, sharing navigation to this attraction for nuclear-age obsessives.

It sounds like it should look flashy. It doesn’t. The soil doesn’t glow. The air doesn’t smell. But the Superfund site still, today, contains traces of radioactive uranium.

“Can you imagine it?” asks Amy Gaskill, a U.S. Army Corps of Engineers outreach specialist for the Formerly Utilized Sites Remedial Action Program (FUSRAP). She’s standing on the bridge, high over the industrial ground. Her colleague, fellow public affairs specialist Andre’ M. Hampton, glances over his shoulder as a semi-truck startles him, thundering across the bridge and shaking the sidewalk.

Gaskill juts a finger through the diamond-link fence to point down at the concrete slabs, orange fencing, rail lines, scraggly bushes, dusty roads and excavation equipment.

A buzzing industry once stood on this now-vacant site. People and colors and smells. Chemical-laden river waters lapped the banks. Smoke snaked up near the hilly residential neighborhoods down the road.

It’s hard to imagine. 

Today, 80 years after the atomic bombs were dropped, traces of radiation remain. But there are fewer every day: The Army Corps is completing its lengthy FUSRAP cleanup project, which started in September 2024 after a $13.4 million contract between the Army Corps and Enviro-Fix Solutions.

As for the land’s future: It’s likely to stay industrial, but parts of it have been proposed for retail and recreational use in past city plans, says a Cleveland spokesperson.

The history of the site remains, even as its physical footprint is washed away. Formerly classified Manhattan Project history volumes and documents mention both “Harshaw Chemical Co.” and “Cleveland” many times. Company and city histories are interwoven, in letters and company ledgers stored at Western Reserve Historical Society; in interlinked webs of online blogs and government pages; in dose reconstruction reports; in decades’ worth of news articles. The story’s threads unspool in the industrial land Harshaw once occupied and the surrounding hilly communities, with stitches from city planners, cleanup crews and workers’ families. The edges fray with time.

And yet, it’s not talked about.

A small company pamphlet preserved in a manila folder is stored deep in the archives in the Cleveland Public Library’s main branch. Published in 1934, the document preceded Harshaw’s uranium work by seven years. It shares context about the company’s early history. It begins with a quote from French novelist Honore de Balzac: This sublime privilege of prolonging the life in our hearts by the life of the work we leave behind us is a reward indeed for all the labor undertaken by those who aspire to such immortality.

Local history books like the Harshaw-produced Tested By Time are filled with midcentury photos and illustrations of the site, along with its story. The business started small in the 1890s and created a network of plants in Cleveland, Elyria, Philadelphia and Hastings-On-Hudson, New York. Later, the company aggressively expanded, even opening international offices in Europe.

At Harvard-Denison, smokestacks, silos, pipes, offices and large two- and three-story red brick buildings popped up on a sprawling property used to produce nickel salts, pigments, acids and other chemicals by the early 1900s. 

This plant’s most consequential work occurred in the 1940s and ’50s, during the uranium years. Specifically, Harshaw streamlined an efficient way to use fluorine gas to produce uranium hexafluoride, a key to uranium enrichment. By 1944, Harshaw ran a dedicated production area, according to Manhattan Project records. It was a major step forward.

“The atomic bomb couldn’t have been made if a group of chemists at Harshaw hadn’t developed a way of making fluorine economically and swiftly,” reported The Cleveland Press in 1954. “For several years, Harshaw was the government’s only supplier.”

RELATED: Uranium Enrichment Today: Centrus Energy Corp. Eyes Expansion in Southern Ohio

To meet Manhattan Project demands, Harshaw made and sent 1,615 tons of uranium hexafluoride, along with large amounts of uranium tetrafluoride, or “green salt,” to the K-25 Gaseous Diffusion Plant in Oak Ridge, Tennessee, for enrichment. It was there that the products were transformed into uranium-235, the chemical used to test and create the atomic bombs the military dropped on Hiroshima and Nagasaki.

And it all happened in secret.

As the Tested By Time book details: The word ‘uranium’ was never used. … Here, a dedicated group struggled with priorities, scarce equipment, security clearances, accountability for every ounce of uranium raw material, and shortages of manpower.

It was difficult and hot. Chemists, foremen, engineers, loaders, operators and cleaners worked to meet the demand for the precious wartime chemical. The factory ran 24 hours, seven days a week — all in the race against Germany to build the bomb that ended World War II.

After he returned from overseas deployment, Chris Mallin’s father picked up his life where it left off and was re-hired at Harshaw’s Harvard-Denison plant.

“That was a period of time that the uranium processing was going on, and he was a night-shift supervisor,” Mallin recalls. “He wasn’t working specifically on the uranium, but he would have responsibility for the entire plant operation shift.”

Mallin, sitting in a side room at Bedford Falls Cafe, makes it clear that he doesn’t want his father named in this article. He sips tea out of a foam cup. Without sharing his name, he gives a few details about his dad. He spoke three languages: English, Polish and German. Living on East 69th Street, he first found work at Harshaw as a young adult. He graduated from Cleveland’s South High School in 1938, then got a bachelor’s degree in chemistry from Western Reserve University, before he was deployed to France just 10 days after D-Day.

He served in the U.S. Army until the end of the war and then spent a year in Europe evaluating evidence for war crime prosecutions, translating interviews for Polish victims of concentration camps, Mallin says.

At the end of the year, he returned to the U.S. He married Mallin’s mother. He worked at the Harvard-Denison plant until 1955 before moving up to corporate headquarters on Cleveland’s East 97th Street. “Life was good,” Mallin says.

Then, 15 years later, at 40 years old, his cancer was first detected. He died in 1977 at the age of 55.

“The doctors did suspect that it might have been caused by the radiation,” Mallin says. “There hadn’t been any family history of cancer.”

Mallin’s father wasn’t the only employee who got sick.

It’s a difficult reality for some Clevelanders. One woman who grew up in the neighborhood said it was too painful to discuss. “There’s a lot of grief and sorrow connected with all this,” she explained in a voicemail, “with the men that worked there.” She didn’t return further phone calls.

Precautions at the plant included respirators and protective clothing, but many Harvard-Denison workers were still exposed to high levels of radioactivity and, studies found, faced heightened risks of cancer.

Workers in the so-called Area C inhaled “2 to 150 times the maximum preferred quantity of uranium” every workday — along with exposure to high beta and gamma radiation levels in operating areas, according to Atomic Energy Commission letters and surveys in 1947. Tests also showed elevated uranium levels in their urine.

Despite the available data, the company downplayed workers’ exposure. It claimed materials were “slightly radioactive” in 1945 security information it drafted for Area C employees, following Atomic Energy Commission concerns.

“You are in no danger and that there is no cause for fear or worry from this source. We are being super-careful in handling this material so that there can be no possibility whatsoever of any damage produced by the very slight radioactivity of this material,” the notice read.

The numbers told a different story. In 2000, the Institute for Energy and Environmental Research showed that Harshaw and two other uranium processing sites’ highest radiation doses corresponded with a 200% rise in the risk of fatal cancer when compared to unexposed individuals.

“Working conditions were appalling,” said Arjun Makhijani, president of IEER and principal author of the project, in a news release from the time. “Data from all three factories that we studied show that the radiation protection standards of the time were routinely violated. And there is incontrovertible evidence that the government, putting production first, failed to adequately protect the workers or properly inform them of the severe hazards that many of them faced.”

In-the-moment reports detailed dust accumfulating or visibly spilling onto the factory floor — and with it, radiological contamination. A 2007 dose reconstruction project for the Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health showed a lack of employee monitoring and, especially in the plant’s early uranium years, a lack of effective exhaust and dust filters. Merril Eisenbud, the former director of the U.S. Atomic Energy Commission’s Health and Safety Laboratory and manager of the New York operations office, said in a 1995 oral history that plants operated by Harshaw in Cleveland and Mallinckrodt in St. Louis had the worst levels of radiological exposure to employees he had seen.

“The exposures were very high,” Eisenbud said in the interview. “I think the maximum amount of uranium in air was supposed to be 50 micrograms per cubic meter; we were measuring milligrams per cubic meter, and they were excreting as much as a milligram a day in their urine.”

The plant’s workers — many of whom would be the parents, grandparents and great-grandparents of the city’s Brooklyn Centre and Old Brooklyn neighborhoods — are now gone. An organizer of “The Harshaw Gang,” an independent reunion blog for former employees of the chemical company, said that none of the remaining Harshaw retirees have any first-hand knowledge of the company’s uranium processing years, which ended in 1955. Those employees are gone.

Some received compensation. Decades of lobbying to support nuclear workers led to Ohio U.S. Senator George Voinovich introducing the Employees Occupational Illness Compensation Act in May of 2000. It passed Congress, and President Bill Clinton signed it into law that year. The program paid out more than $25 billion to workers involved in nuclear weapons production who contracted certain cancers and other illnesses. Of that, about $7 million went to Harshaw’s workers and their families. Many millions more were paid out to workers of Brush Beryllium Co., research laboratories and other manufacturing plants that peppered Northeast Ohio and also contributed to the Manhattan Project.

Mallin’s father didn’t directly handle uranium, but he would’ve regularly been exposed to its dust while working at the Harvard-Dennison plant. When the compensation program was approved, Mallin’s family submitted a claim.

“We had a medical review of his medical record, and (it) concluded that there was a greater-than-50% chance that the cancer was caused by radiation exposure,” Mallin says.

Roughly 30 years after Mallin’s father died, his family received compensation — bookending just one experience of Cleveland’s atomic age.

Harshaw, like other Ohio companies, contributed to the “Arsenal of Democracy” wartime efforts that pivoted factories’ regular uses toward military manufacturing. It was honored with an Army-Navy “E” Award, sporting four stars: a testament to the Harvard-Denison plant’s contributions to the atomic bomb’s development. Other contributors included uranium rod manufacturers in Columbus and Toledo, a polonium-making factory in Dayton, and dozens of other  Ohio factories crafting pieces and parts for the war.

Mallin calls many of those factory workers patriots.

“If a guy was 30 years old in 1955 working at Harshaw, that means that 10 years earlier, he was wearing a uniform in the United States armed services. The guys that were working at Harshaw at that time virtually were all veterans of the military. A great number of them had served in World War II,” Mallin says, “but they probably did not have the kinds of disclosures about what health risks were involved at the time.”

Mallin says his dad, a chemist, understood uranium and its radioactivity, and he even likely knew how the product would be used in wartime. But he never spoke about it while he worked for Harshaw. “That was not anything that anybody talked about, because it was a defense contract,” Mallin says.

Yet, neighbors knew something was going on at the plant. As Harshaw continued to process uranium after World War II ended, community members became concerned about the factory’s pollution of Brooklyn Centre and Old Brooklyn. Neighbors complained of odors from the factory and etching on glass panes and windows of cars parked nearby, as noted in a 1947 report by the Atomic Energy Commission.

Conditions improved when, in the late ’40s, the company installed more effective exhaust hoods, filtration, cleanup and laundering systems. In December 1951, the commission began decontaminating some former uranium processing spaces, while other parts of the plant ramped up. Harshaw worked with or stored various forms of uranium until 1955, when its contract with the government ended and the commission directed the company to end processing.

By late 1956, the commission ordered the area office to dismantle Harshaw’s uranium plant. Commission-supervised decontamination continued through 1960. As for the company itself, after several mergers and acquisitions, Harshaw’s properties took on different names and functions, and the Harvard-Denison plant ceased all operations in 1998.

Property owners worked on decontamination in the 1990s, demolishing some of the campus, with remaining factory buildings coming down in 2015. Around that time, the site became a hot topic during the development of the Ohio & Erie Canal Towpath Trail. Trail organizers reportedly aimed to thread through the former Harshaw grounds along the river, but plans changed because of the lengthy cleanup.

As this former self fades, the city must reckon with its history, says city councilwoman Rebecca Maurer. Her ward touches the Harshaw site.

“The Manhattan Project, and dropping the atomic bomb, was one of the most consequential and damaging and intense acts of war that the United States of America has ever engaged with,” she says. “It’s certainly unsettling to know that any element of that work happened literally in the heart of Cleveland on the Cuyahoga River.

“If anything, I’m grateful to the FUSRAP team and the FUSRAP project for bringing to light this history and helping us understand Cleveland’s involvement in it and Harshaw’s involvement in it.”

Maurer helped host public information sessions last year, where the Army Corps shared its process. It looks something like this: Excavation is followed by radiological testing, then sealing the contents “a bit like a burrito,” then loading them into trucks, decontaminating and more radiological testing — all before the truckloads of soil even leave Cleveland, says Katie Buckler, the Army Corps’ project manager for the Harshaw site. Air monitors run 24/7 around the site to detect radiation.

“We want to make sure everybody is aware that we’re doing everything safely, making sure the workers are safe, the communities are safe,” Buckler says.

The site is divided into three operable units. Two are nearing completion. Most of the  work remains in Operable Unit-1 North, which once held Harshaw’s G-1 building, responsible for most uranium processing.

As of Aug. 12, 13,361 cubic yards of soil and concrete have been sealed, tested and transported for disposal in Wayne Disposal Facility in Belleville, Michigan, near Detroit. But what is considered decontamination here is seen as contamination elsewhere: In early August, Michigan communities near Wayne Disposal won a court order to prevent radioactive FUSRAP waste from being sent in.

Now, along with ongoing excavations, Harshaw also holds stockpiled waste awaiting disposal, with weekly inspections.

It’s not an unusual practice, Buckler says, and cleanup efforts are unaffected. She expects FUSRAP field work to wrap up this winter and to close out by the end of 2026.

So many decades after uranium processing, the cleanup crews are still unearthing radiation in the ground.

“Contractors on site are saying, ‘We’re finding yellowcake in the soils,’ which is what we were expecting,” Buckler says. “But just seeing it right there is always a little bit — you know, not shocking, but also interesting, to just see it sitting there, in the soils. It validates us for sure, to let us know we’re actually cleaning up some pretty dangerous stuff, and getting it taken care of.”

It’s classified as “low activity radiological waste,” Buckler clarifies.

Harshaw, in some ways, is a straightforward cleanup. Ohio’s other active FUSRAP site, Luckey, housed a Brush Beryllium Co. facility and was linked to radioactive groundwater contamination in a recent Toledo Blade investigation.

Other FUSRAP site cleanups took focus before Harshaw. Plus, it took time for Congress had to approve funds for the Army Corps to do the work in Cleveland, Gaskill says. Once it got started, the Army Corps moved slowly, aiming to fully investigate the property and understand its story, and to share that information with the neighborhood. 

“Before we start digging, we really do want to make sure we have a really firm idea of what we’re getting ourselves into,” Gaskill says.

For more than 25 years, the Army Corps has managed Harshaw’s uranium remediation. After FUSRAP wraps up, more cleaning remains as a part of Resource Conservation and Recovery Act work managed by the US Environmental Protection Agency.

“It is uncommon that a property or area is subject to both cleanup programs simultaneously,” says EPA spokesperson Molly Vaseliou.

The radioactive cleanup takes priority. Then, the EPA and BASF, the European chemical company that owns some of Harshaw’s property, will step in to address the hazardous waste remaining from the plant’s longtime nickel salt, cobalt oxide and pigment production.

“Because of these activities, the site is mainly contaminated with metals,” says Vaseliou. “The most affected areas of soil and groundwater are linked to past wastewater treatment and waste disposal practices.”

Mallin followed his father’s footsteps and picked up work at Harshaw in summer and winter breaks of 1969 while he was an undergraduate student, working with nickel chloride and the plant’s chrome-plating process. “It wasn’t radioactive, but that’s about all I can say for it, as far as being pleasant,” Mallin says.

He saw industrial pollution in the Cuyahoga River: bright plumes of orange that he attributed to the nearby steel mill operations, and other reactions blooming in the waters, too. “From one day to the next, it had a variety of bright colors,” Mallin remembers.

Five decades have passed. The EPA formed and environmental efforts addressed the water. Today, the river has returned to a natural muddy brown.

Soon, the former site of the plant may find its own non-toxic future.

Eighty years after the atomic bomb was dropped, the world continues to reflect on its legacy. Another like it has not been deployed, though the potential hangs over geopolitics like a mushroom cloud.

Cleveland played a role in this reality.

In a 1945 speech, J. Robert Oppenheimer, the physicist behind the development of the bomb, told his colleagues that “this is not only a great peril but a great hope.” Today, nuclear energy accounts for nearly 20% of the country’s electricity generation. The industry is expanding, especially in Ohio, with two new power plants planned in the state.

Cleveland, too, played a role in this reality.

This reality, like a patchwork quilt, sewn together. This relatively small, industrial lot which curves in a gentle “C” shape around the Cuyahoga River. And hundreds of other grounds just like it. All working together to create one world-shifting invention. All contending with the scars left behind.

This historic corner of the city will turn to its next chapter, but its history will never be scrubbed away.

Cleveland played a role.