Federal regulators are being asked to end a nearly 30-year-old determination that exempts the white, radioactive waste material and related acidic water in a St. James Parish gypsum pile from being considered hazardous waste.

A collection of environmental and community groups has asked the Biden administration's U.S. Environmental Protection Agency to begin what they say is an overdue review of the material, known as phosphogypsum. That review could end up having it declared a hazardous waste, require new health testing of its effects and block the Trump administration's decision last fall to let the waste be used for road base in government projects. 

The waste pile at Mosaic Fertilizer's Uncle Sam complex along the Mississippi River near Convent gained some attention two years ago.

The company and state regulators discovered in late 2018 and early 2019 that a nearly 190-foot-high wall of the waste had been gradually shifting north and, it was feared initially, could have affected the integrity of a huge lake of acidic process water stored at the top of the pile. 

Since then, a variety of measures have taken pressure off the northern wall by shifting or moving hundreds of millions of gallons of acid water to other lakes and by reshaping the waste pile's northern face and interior.

The wall's movement has slowed considerably. The risk to the large lake of acidic water atop the pile wasn't as severe as first thought, company reports say.

However, the Center for Biological Diversity and an array of community groups in Florida, Louisiana and other states where such waste piles are common say the more than 70 piles nationwide continue to threaten nearby communities, waterways and groundwater. 

“These towering stacks of radioactive waste continue to pose an unacceptable risk to the environment and nearby communities,” Jaclyn Lopez, Florida director at the Center for Biological Diversity, said in a statement. “They’re prone to massive sinkholes and spills that put our groundwater and recreational waters at risk and threaten public health. The EPA must face the facts and act quickly to avert the next environmental disaster.”

Four southeast Louisiana groups — Atchafalaya Basinkeeper, Healthy Gulf, Rise St. James and the local chapter of the Sierra Club — joined the administrative petition filed with the EPA earlier this month.

In December, the Center for Biological Diversity and some of the same groups separately sued and petitioned the EPA to block the Trump administration's authorization of the use phosphogypsum for road construction.

In part of the newer appeal to EPA, the groups cite the St. James pile's shifting wall as an indication that gypsum piles have been built on weak soils and are unstable and that many, like the one in St. James, are located near lower-income communities who will bear the worst health effects.

The waste pile in St. James covers about 960 acres and is a little more than 200 feet high in some spots, permit filings say. Mosaic was required a few years ago to install FAA warning lights at the top of the pile to protect local aircraft. The pile is visible from the Sunshine Bridge during the day. 

"Phosphogypsum" is a byproduct of making phosphoric acid for agricultural fertilizer production but is laced with a variety of heavy metals, as well as radioactive elements like radium-226 and uranium, which have made it hard to reuse and, the environmental groups say, make it a risk to the public. 

Radium-226 raises a particular concern because as it decays it releases radon gas, a known carcinogen.

More than five pounds of phosphogypsum are created for every pound of phosphoric acid. The Uncle Sam plant has been piling up the powdery, chalk-colored material since 1975, and finding a new use for it like road base would slow the stacking process.

Jackie Barron, a spokeswoman for Mosaic, said phosphate fertilizer manufacturing is a heavily regulated industry already and further restriction could harm U.S. food production. 

"Let’s be clear — the petition opposing the domestic fertilizer industry threatens the food supply in the United States," Barron said. "The majority of food grown here starts with nutrients produced in America. Eliminating domestic production will ripple through the U.S. economy, and only will benefit foreign producers, which are not subject to the same environmental standards that exist here."

Mosaic is already under a 2015 EPA consent decree over alleged violations in its management of the acidic process water. 

Barron didn't say exactly how a change in rules would affect Mosaic's processes or employment levels.

The plant has about 400 workers. Mosaic had to furlough about 370 of them for two months in late 2019 due to a market oversupply of agricultural fertilizer.

About 50% of the phosphate industry's annual phosphoric acid production is sold and shipped to overseas buyers, but the environmental groups say in their petition to EPA that 100% of the phosphogypsum waste remains in the United States.

In 1980, Congress adopted the Bevill Amendment. It declared phosphogypsum and many other mine wastes as "special wastes" that needed extra review before they could be determined to be hazardous waste.  

In 1991, after a review, the EPA found that phosphogypsum and acidic process water were not hazardous waste. The finding allowed them to be treated as a solid waste as long as they continued to be held in piles, with some exceptions, and that radioactivity emitted from the piles was kept to certain levels.

Part of that decision involved the economic cost, EPA found, that classifying phosphogypsum as hazardous waste would mean for the fertilizer industry.

In the early 1990s, though, the EPA did find that the waste, even isolated in stacks, raised the maximum possible lifetime cancer risk from inhalation of gypsum dust by people living within 50 miles of the mountainous piles. But the higher risk, 0.9 chances in 10,000, was slightly safer than the federal minimum acceptable standard of a 1-in-10,000 cancer risk. 

Barron, the Mosaic spokeswoman, said the groups' latest petition is trying to overturn an EPA decision that "was based on data and extensive research."

"That said, both process water and phosphogypsum at Mosaic’s facilities are managed in ways that are protective of the environment and the communities where our employees live and work," she said.

Barron added that EPA's recent approval of the use of phosphogypsum for roads is not new but was also based on substantial science.

In December, the Center for Biological Diversity pointed out that the EPA had barred the use of phosphogypsum for roads since its Bevill Amendment reviews in the late 1980s and that the Trump administration was ignoring its own expert consultant about the risks in authorizing the new use.

Email David J. Mitchell at dmitchell@theadvocate.com

Follow David J. Mitchell on Twitter, @NewsieDave.