52 ELR 10126 ENVIRONMENTAL LAW REPORTER 2-2022
failures of these ticking time bombs, the moment is ripe
for EPA to take back federal control and put an end to
these environmental and public health hazards. is Arti-
cle examines the rise of phosphogypsu m stack s and their
placement th roughout vulnerable c ommunities and sensi-
tive environments in the United States, and explains how
President Biden’s EPA has the authority and obligation
to rein them in. It does not document the harm from the
phosphate min ing that make s phosphogypsum pro duction
possible, the direct water pollution from fertilizer factory
euent, or the impacts of pesticide and fertilizer applica-
tion or runo that result from the use of synthetic fert ilizer,
nor does it analyze the regu latory frameworks for address-
I. What Is Phosphogypsum?
Phosphogypsum is the radioactive, toxic wa ste created dur-
ing wet-proces s phosphoric acid production. Phosphoric
acid is the intermediate feedstock of granular and liquid
ammonium phosphate fertilizers. In the United States,
phosphoric acid is produced from phosphate rock mined
from mineral deposits in Florida, Idaho, North Carolina,
and Utah, with the largest deposit and the majority of the
nation’s phosphate mining occurring in Florida, where 27
strip mines span more than 450,000 acres.
After strip mini ng and beneciation to remove sand and
clay from the phosphate matrix, calcium phosphate ore is
transported to a fertilizer plant for processing by chemi-
cally digesting the phosphate ore in sulfuric acid.¹ is
reaction results in a slurry of phosphoric acid and phos-
phogypsum (calcium sulfate di hydrate or calcium sulfate
hemihydrate, depending on the type of wet process) as a
suspended solid, at a rate of 5.2 tons of phosphogypsum
waste for every one ton of phosphoric acid.¹¹ e phos-
phoric acid solution i s ltered from the phosphog ypsum
and concentrated through evaporation to be sold as mer-
chant-grade phosphoric acid, feed-grade phosphoric acid,
and superphosphoric acid, or used as feedstock for nished
fertilizer products like d iammonium phosphate (DAP) or
monoammonium phosphate (M AP).¹²
e phosphogypsum waste is then reslurried with recy-
cled process wastewater and pumped via pipeline for dis-
posal in a settling pond impoundment atop a waste pile
known as a phosphogy psum stack,¹³ where the phospho-
7. U.S. EPA, TENORM: Fertilizer and Fertilizer Production Wastes, https://
(last updated Nov. 5, 2021).
8. U.S. G S, M C S 2020
9. Id.; FDEP, Phosphate, https://oridadep.gov/water/mining-mitigation/con-
tent/phosphate (last modied Sept. 15, 2021).
10. U.S. EPA, R C S W F M
P 12-1 (1990), https://www.epa.gov/sites/default/les/2015-05/
documents/2000d96z.pdf [hereinafter R C].
11. U.S. EPA, supra note 7.
13. Alternatively called “pond water” by industry and state regulating agen-
cies. See FIPR Institute, Process Water, https://pr.oridapoly.edu/about-us/
phosphate-primer/process-water.php (last visited Dec. 10, 2021) (Typical
Pond Water Analysis table). “Process wastewater” also includes phospho-
gypsum sett les, thereby growing the stack.¹ e settled
phosphogypsum is dredged to build up embankments
at the sides of the impoundment containing the process
wastewater.¹ Cooling ponds containing process wa stewa-
ter are also situated at or below grade along the perimeter
of the stack.¹ e process wastewater is meant to be pri-
marily recycled in fert ilizer plant operations, making unin-
terrupted plant operation critical to maintaini ng a negative
process water balance.¹ Even still, during periods of precip-
itation, discharges to surface waters are often permitted.¹
While modern, active stack s and adjacent cooling ponds
are lined with a single synthetic geomembrane liner, these
liners can tear and are designed to leak (i.e., permeable),
creating a “zone of discharge”¹ in the surcia l aquifer that
in some cases is explicitly allowed by permit.² As a stack
grows in height, the settling impoundment atop the stack
decreases in size until the settling pond capacity becomes
too small and the pumping height requires too much ener-
gy. ²¹ At this point, the stack is either expanded horizon-
tally, or it reaches the end of its useful life.²²
Phosphogypsum conta ins ca lcium sul fate and m any
contaminants, including rad ionuclides from uranium, tho-
rium, and radium, which decay to harmf ul radon gas; toxic
heavy met als; uoride; ammonia; and re sidual phosphoric
and sulfuric acids.²³ e process wastewater also contains
these harmfu l toxic constituents and is highly acidic and
corrosive, with pH (hydrogen ion concentration) measure-
ments as low as 0.5.²
Phosphogypsum stack systems a re prone to extensive
groundwater contamination, dike breaches, leakage, unex-
plained seepage, sinkholes, instability that threatens out-
right collapse, and excess process water balances in the
event of a plant shutdown or abandonment necessitating
intentional large-volume releases of process water to pre-
vent furt her cata strophe.² Further, this underregulated
gypsum stack runo, wastewater generated from the uranium recovery
step of phosphoric acid production, process wastewater from animal feed
production, and process wastewater from superphosphate production. Min-
ing Waste Exclusion, Final Rule, 55 Fed Reg. 2322, 2328 (Jan. 23, 1990).
Uranium recovery from phosphate processing became uneconomic in the
1990s. Gerald Steiner et al., Making Uranium Recovery From Phosphates
Great Again?, E’ S. T. 1287 (2020), https://pubs.acs.org/doi/
14. R C, supra note 10, at 12-4.
17. Id. at 12-2.
19. e horizontal extent of a permitted zone of discharge is typically the prop-
erty boundary, but groundwater contamination exceeding drinking water
standards often extends well beyond the zone. R C, supra
note 10, at 12-13.
20. F. A. C r. 62-673.320(6) (2013).
21. Olice C. Carter et al., Investigation of Metal and Non-Metal Ion Migration
rough an Active Phosphogypsum Stack, in I L R-
M D C T I C-
A A D 199 (U.S. Department
of the Interior 1994).
22. Id.; see also Ardaman & Associates, Phase III Expansion Application, Mosaic
Fertilizer, LLC—New Wales Facility, FDEP Permit #MMR_FL0036421
(Oct. 25, 2019); R C, supra note 10, at 12-31.
23. R C, supra note 10, at 12-3.
24. Id. at 12-4.
25. Id. at 12-31.
Copyright © 2022 Environmental Law Institute®, Washington, DC. Reprinted with permission from ELR®, http://www.eli.org, 1-800-433-5120.