Leachate. This term refers to the liquid that has passed through or emerged from phosphogypsum.
Liner. This term refers to a continuous layer of low permeability natural or synthetic materials which controls the downward and lateral escape of waste constituents or leachate from a phosphogypsum stack system.
Phosphogypsum. This terms refers to a preparation of calcium sulfate and its byproducts that are produced by the reaction of sulfuric acid with phosphate rock to produce phosphoric acid. Phosphogypsum is a solid waste within the definition of Section 403.703(13), F.S.
Phosphogypsum stack. This term refers to any defined geographic area that is associated with a phosphoric acid production facility in which phosphogypsum is disposed of or stored, other than within a fully enclosed building, container or tank.
Phosphogypsum stack system. For the purposes of this study, this term means the phosphogypsum stack (or pile, or landfill), together with all pumps, piping, ditches, drainage conveyances, water control structures, collection pools, cooling ponds, surge ponds and any other collection or conveyance system associated with the transport of phosphogypsum from the plant to the phosphogypsum stack, its management at the stack, and the process wastewater return to the phosphoric acid production or other process. This definition specifically includes toe drain systems and ditches and other leachate collection systems, but does not include conveyances within the confines of the fertilizer production plant or existing areas used in emergency circumstances caused by rainfall events of high volume or duration for the temporary storage of process wastewater to avoid discharges to surface waters.
Overview of Study
This is a historical/case study analysis of what problems face companies in their toxic waste disposal practices in general and for phosphogypsum stack systems in particular, and what steps policymakers can take to help them achieve a safe disposition of these potentially hazardous materials. Chapter Two provides a review of the peer-reviewed literature and a discussion of the above issues; Chapter Three
Chapter 2: Review of Related Literature
Background and Overview.
According to Frazer, Gilroy and Rabe (1994), the domestic application of industries that require toxic materials as part of their operation has traditionally been characterized as a collective good that has been worth any inherent risk in its development. For example, millions of North Americans enjoy relatively inexpensive energy from modern nuclear power plants: "Thousands benefit from the post-world War II application of nuclear technology to medicine. From the formation of national regulatory entities in both nations through the 1970s, few people in either nation challenged the conventional wisdom that massive federal government subsidies for the development of nuclear power and medicine were anything other than a worthy endeavor which served broad, collective goals" (p. 67). That consensus, though, has been increasingly challenged in recent years, in part because of the issue of radioactive waste disposal. Disasters such as Chernobyl and near-disasters such as Three Mile Island drew attention to the safety of facilities generating nuclear power, but the issue of waste disposal poses a separate set of challenges for both nations. While nuclear power and nuclear medicine are perceived as collective goods, Canadians and Americans alike recognize radioactive waste as a threat to public health, environmental protection, and the economic stability of any community which might become contaminated (Frazer et al., 1994).
These threats were recognized early on throughout North America, but regulatory bureaucracies and powerful business interests delayed any substantive legislation for a number of years. For instance, the 1976 Resource Conservation and Recovery Act (RCRA) emphasized safer, better methods of land disposal. These new rules called for standards for liners, leak detection systems, leachate collection, and other initiatives. A number of significant regulations from the Environmental Protection Agency (EPA) were delayed for four years, though, and then emerged only in response to growing public concerns over the many source points releasing toxic wastes across the country.
According to Mazmanian and Morell (1992), by the time EPA's landfill regulations appeared in 1980, initiatives in several states had already begun to shift focus away from landfilling of this continuing flow of huge volumes of new hazardous wastes. As more information became available on the dangerous environmental consequences of relying on land disposal for these wastes, Congress took steps to redress the balance in favor of treatment. In late 1984, the Hazardous and Solid Waste Amendments (HSWA) to RCRA set a new tone for national hazardous waste policy. Strict congressional guidelines called on EPA to ban land disposal nationwide of most hazardous wastes, including the entire "California list." Federal bans were to take effect between 1989 and 1992. Illinois adopted similar restrictions, though on a faster schedule; California accelerated its phase out program.
Despite popular misconceptions, most prescribed hazardous waste treatment is neither exotic nor exorbitantly expensive. Perhaps 80 to 90% of all the hazardous wastes being generated in the United States could be treated by modern variants of 1930s-era wastewater treatment technologies (Mazmanian & Morell, 1992).
Acids can be neutralized while held in steel tanks; metals can readily be removed from liquid waste streams. In both cases, the remaining liquids can then be discharged safely into sewers available in every industrial area. Waste oils and solvents can be recycled through traditional separation and distillation techniques (akin to small refinery operations). Another 10% of today's hazardous wastes probably require thermal destruction in a rotary-kiln or fluidized-bed incinerator, which can be equipped to function safely using the latest air pollution control technology (Mazmanian & Morell, 1992).
The problem of hazardous waste management does not end with treatment alone, though; all these treatment methods leave residues requiring land disposal: sludge, ash, and typical residuals from pollution control equipment. Heavy metals, in particular, are ultimately amenable only to land disposal. Dried and stabilized, they can be stored safely in a new kind of landfill -- a "residuals repository" -- that uses a permanent cover to protect them from rain or snow. Such facilities already exist in Europe but not yet in the United States. With no liquids in the waste residues allowed for disposal in the residuals repository, and none entering from precipitation, no leachate can be formed to threaten nearby groundwater. Several decades hence, perhaps we can even reclaim the metals economically from carefully managed hazardous waste repositories (Mazmanian & Morell, 1992).
Treating hazardous wastes instead of dumping them on the ground obviously requires new treatment facilities. Within the context of the widespread fear of toxics, few communities will consider siting such facilities, even those employing the newest and most advanced treatment facilities. People do not want someone else's wastes brought into their community for treatment, irrespective of purported treatment facility safety. Consequently, during the first toxics decade, siting new treatment facilities proved to be one of the major stumbling blocks to realizing the treatment "solution" to hazardous waste management. By the mid-1980s, a few communities were beginning to see treatment facilities as an integral part of their overall waste management strategy, but it would take even more effort in these communities to accomplish siting of these facilities; elsewhere, successful siting seemed a virtual impossibility (Mazmanian & Morell, 1992).
Fluoride Leachate Contamination.
Radiation and Phosphogypsum.
Both natural gypsum and phosphogypsum contain radioactivity, but phosphogypsum contains more. In the manufacture of phosphoric acid, the acid is filtered through cloth to remove solids. The radium is filtered out with the solids. The solid portion is known as phosphogypsum. Phosphogypsum produced in North Florida contains roughly 5-10 picocuries per gram (pCi/g) of radium while phosphogypsum from Central Florida contains about 20-35 pCi/g radium.
The U.S. EPA prohibits the use of phosphogypsum. An exception is made for phosphogypsum with an average concentration less than 10 pCi/g radium which can be used as an agricultural amendment. EPA's ban was based on a single scenario which assumed that the by-product was used in road building or as an agricultural amendment and 100 years later a house was built on the farm field or the abandoned road and the homeowner lived in the house 70 years, staying in the house 18 hours a day. Under this scenario the homeowner's risk of radon-related health concerns only slightly exceeded the EPA's acceptable limits.
Phosphogypsum is primarily calcium sulfate, and plants need the sulfur it contains. Since much of the North Florida phosphogypsum is below the EPA restriction level, it can be used as a crop amendment, but for no other use.
The Central Florida phosphogypsum is restricted to storage on land in large piles called "stacks." The overall radioactivity in the stacked phosphogypsum is actually less than what was in the original phosphate ore that was taken out of the ground (Phosphate Primer, 2005).
International initiatives for the control of phosphogypsum stacks have included those by the…