For more than 20 years, Gypsum Association members have successfully and safely developed and deployed technologies to use flue gas desulfurization (FGD) gypsum as a key ingredient in the manufacture of gypsum board (AKA wallboard or drywall). The gypsum industry purchases FGD gypsum from electric utilities who employ a washing and purification process to make FGD materials into an FGD gypsum product. Natural gypsum and FGD gypsum have the same chemical composition; they are each calcium sulfate dihydrate (CaSO4·2H2O). Today, almost half of all gypsum used in the manufacture of gypsum board in the United States is FGD gypsum, also known as synthetic gypsum.
All gypsum board, including FGD gypsum board, manufactured by members of the Gypsum Association is produced in compliance with consensus standard ASTM C1396, Standard Specification for Gypsum Board. Compliance with the C1396 standard is mandated by model building codes in the United States.
The wallboard ingredient material, FGD gypsum, is a manufactured product and not a waste. Electric utilities use a multistep manufacturing process in order to meet precise gypsum industry product specifications for FGD gypsum. The resulting grade of FGD gypsum, commonly called “washed FGD gypsum,” used to manufacture gypsum board is a specific unique product and is not fly ash, bottom ash, or other Coal Combustion Residuals (CCR); nor is it the same as “FGD sludge” or unwashed FGD materials.
Importantly, studies have universally shown washed FGD to be safe. It is chemically identical to natural gypsum rock, as well as comparable in its constituent elements and characteristics. Gypsum has been affirmed by the U.S. Food and Drug Administration (FDA) as an additive for human consumption in food products.
Nonetheless, to ensure for appropriate practices, the Gypsum Association retained ARCADIS, a global environmental consulting firm, to evaluate data concerning washed FGD gypsum and assess whether it and FGD gypsum wallboard were safe and environmentally responsible. Based on that review, ARCADIS determined that the grade of FGD gypsum used to manufacture gypsum board is not hazardous, either when encapsulated in a finished material or in an unencapsulated form. Moreover, ARCADIS concluded that none of the published analyses of FGD gypsum presented any scientifically defensible information suggesting that washed FGD gypsum poses any environmental or human health concern. To the contrary, all available data confirmed the safety of the product and the absence of any risk to human health or the environment.
Significantly, the Risk Evaluation information released by EPA regarding FGD gypsum fully supports the views of the gypsum industry regarding the safety of gypsum board manufactured with washed FGD gypsum. The Gypsum Association has consistently stated – and EPA confirms – that the metals present in washed FGD gypsum are below EPA’s levels of concern. Specifically, in its February 2014 final report Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard, EPA states, “Based on the analysis set forth in this document, the evaluation concludes that environmental releases of constituents of potential concern (COPCs) from CCR fly ash concrete and FGD gypsum wallboard during use by the consumer are comparable to or lower than those from analogous non-CCR products, or are at or below relevant regulatory and health-based benchmarks for human and ecological receptors.” EPA’s evaluation further states, “The beneficial use of CCRs, when conducted in an environmentally sound manner, can contribute significant environmental and economic benefits. Environmental benefits include reduced greenhouse gas emissions, reduced need for disposing of CCRs in landfills, and reduced use of virgin resources.”
EPA’s review corroborates the safety of FGD gypsum and encourages its continued use. The report’s conclusion states “EPA supports the beneficial use of coal fly ash in concrete and FGD gypsum in wallboard. The Agency believes these beneficial uses provide significant opportunities to advance Sustainable Materials Management (SMM).”
The EPA final report on FGD gypsum can be found here.