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Down a Gypsum-Based Road?

By Victoria Parsons

While reclamation efforts at phosphate mines focus on reconstructing the landscape, another by-product of the phosphate industry literally looms high at 25 sites across the state.

For every ton of raw fertilizer produced, the industry generates five tons of phosphogypsum, a radioactive material the U.S. Environmental Agency considers hazardous waste. With limited options available, the phosphate industry is storing more than a billion tons of phosphogypsum in stacks that tower up to 200 feet high - a problem that grows by 30 million tons every year.

What to do with phosphogypsum has been a divisive issue since 1989 when the EPA banned any use of the waste material.

The Florida Institute of Phosphate Research says that the risk of radiation exposure to people working or driving on roads built over a phosphogypsum base is less than that from dental x-rays or watching television. Foes counter that any increase in radiation is potentially harmful and the industry simply wants to get rid of an expensive problem.

"Saying something is slightly radioactive is like saying you're slightly pregnant - you either are or you aren't," says Tom Reese, an attorney in St. Petersburg. "The phosphate industry says the risk is not that great and tries to confuse people about what the issue really is. If there's no benefit to me, I shouldn't have to take the risk, no matter how small."

The radioactive materials in phosphogypsum are naturally occurring and were originally deposited with phosphate ore.

The radium is of particular concern because it decays into radon, a gas that causes an estimated 20,000 deaths from lung cancer every year. However, high levels of radon are found in nearly one of every 15 homes across the country and a review of data conducted by FIPR shows no correlation between counties with high levels of radon (including Polk) and lung cancer deaths.

While the hazards of radioactive compounds in phosphogypsum are still being debated, the risk gyp stacks pose to the state's ecosystems was made clear at Piney Point, the abandoned fertilizer plant where state officials were forced to dump millions of gallons of highly acidic, nutrient-laden water into Bishop Harbor. Accidental releases from phosphogypsum stacks at other plants also have damaged local waterways over the years, including a 41-million gallon spill into a creek that leads to Hillsborough Bay during Hurricane Frances last summer.

Do Benefits Outweigh Risks?

Leading the effort to allow alternate uses for phosphogypsum are Congressman Adam Putnam (R-Lakeland) and Michael Lloyd, FIPR's research director. "Considering the environmental dangers of stacking phosphogypsum, do the unlikely risks associated with the use of it outweigh the risks of storing it as a waste product?" Putnam asked at a March 2003 congressional hearing held in Bartow.

"Scientific research supports a position that phosphogypsum is not a 'waste' but rather a potentially valuable product," he said. "It can be environmentally safe and economically attractive to use phosphogypsum in a variety of ways serving industries and potentially benefiting taxpayers."

FIPR research is focused on three possibilities: roads, landfills and agricultural uses. Prior to the 1989 ban, many roads and parking lots in Polk County were built over a bed of phosphogypsum and are in better shape than new roads, Lloyd said. "Phosphogypsum is a cement-like material that strengthens over time and state road testing equipment shows that roads are in better shape now than when they were built."

Along with roads that last longer, taxpayers could save up to $100,000 per mile of road, or up to $300,000 per mile of interstate highway, using phosphogypsum instead of the more-typical limestone, he said.

One test road, built in 1985 on a reclaimed phosphate mine near Fort Meade, indicates that an asphalt covering minimizes radon gas. "Radon levels over the road were lower than the shoulder where there was no asphalt," Lloyd said. Only one of 15 wells monitoring groundwater indicates any impact, he adds. "It has elevated sulfate but we're not convinced it's from the road since there are mined-out pits on both sides."

The EPA risk analysis that questions the safety of roads built over phosphogypsum beds is based on studies that indicate that someone who builds a house on the abandoned road and lives in it 18 hours a day for 70 years would have more than a 1 in 10,000 risk of cancer. "We think that's a judicious standard, not overly cautious," notes Reid Rosnick of the EPA's Radiation Protection Division.

Even with deed restrictions that would limit construction on an abandoned roadbed, radium has a half-life of 1630 years so both EPA and the Florida Department of Environmental Protection are concerned that records could be lost long before radioactivity declines.

A request by FIPR to build another test road with a phosphogypsum base is in limbo based on those long-term concerns, Rosnick adds. "We're disturbed about what could happen when the road disappears and there isn't any permanent record on where the phosphogypsum was placed. There's been some discussion and it's definitely a potential option, but there's so much room for error, even with today's record-keeping, that I don't think the state of Florida is amenable to the project."

Layered in Landfills?

A second use that potentially benefits taxpayers calls for phosphogypsum to be spread over landfills. Laboratory studies indicate that the nutrients in phosphogypsum, including calcium and sulfur, speed bacterial consumption of waste materials, potentially extending the life of the landfill. High levels of sulfur may enhance anaerobic activity and increase decomposition by 50% over a three-month period.

"We did feel as though that particular alternative use would have no greater risk than phosphogypsum in a stack and proposed to approve the test," Rosnick said.

Brevard County, site of the landfill, withdrew its support based on increased hurricane activities and the need for additional space for a methane gas initiative.

FIPR is looking at other locations across the state. "We've had conversations with three or four counties and so far only one has shown no interest," Lloyd said.

FIPR-EPA Look for Long-Term Solutions

The best use of phosphogypsum, on a world-wide basis, may be agricultural, Lloyd notes. "The world is agronomically very deficient in sulfur and phosphogypsum is the least-expensive sulfur in the world." Adding sulfur to lands used for grazing cattle increases the protein in grass and makes it more digestible for two-stomach animals that may achieve a 20% weight gain on the improved diet.

A six-year study is underway now at Rothamsted Research, the world's oldest agricultural research center, to determine what happens to various components of phosphogypsum, including radionuclides, heavy metals and nutrients. The first phases will be conducted in laboratories. If those results are positive, a third phase is planned for world-wide field experiments to track components and results in a wide variety of settings.

The study at Rothamsted is part of a multi-pronged study designed to survey international uses of phosphogypsum and determine which, if any, uses are both beneficial and commercially appropriate.

"We're certainly hoping for some kind of breakthrough in the future," adds EPA's Rosnick. "We have no plans at this time to revise our regulations or standards, but our friends at FIPR are constantly looking at new ways to use this material."

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