2009 Annual Report
1a.Objectives (from AD-416)
Each year, foundries in the U.S. landfill several million tons of waste sand that can no longer be used to make metalcasting molds and cores. These waste foundry sands are potentially useful as a soil amendment and ingredient in manufactured soils; however, potentially harmful organics and trace metals in the sands may adversely impact the health of humans and the environment. The objective of this project is to ensure that waste foundry sands can be safely used in manufactured soils and related applications.
1b.Approach (from AD-416)
The first part of this study will focus on the identification and quantification of potentially hazardous organics and trace metals in waste sands from ferrous and non-ferrous foundries. As organics and/or trace metals of environmental concern are identified, studies will be conducted to determine their movement potential. Major routes of transport will be investigated and lead to management practices to reduce or eliminate their transport. Blending waste sands with organic amendments will be investigated as a potential means to mitigate these constituents. Investigations will also be conducted to determine if waste foundry sands present a risk to commonly used biological indicators, including soil microorganisms, earthworms, and plants. Bioaccessible trace metals in waste foundry sands, associated with human exposure, will be assessed using an in vitro gastrointestinal method. Finally, to assess the suitability of using waste foundry sands in horticultural and agricultural settings, data from the above mentioned studies will be used to develop a comprehensive risk assessment.
The beneficial use of spent foundry sands (SFS) preserves natural resources by decreasing the demand for virgin materials, conserves energy, reduces greenhouse gas emissions through reduced mining activities, and decreases the economic burdens of disposal. A collection of SFS was analyzed for nutrients, trace elements, and xenobiotics. Potential risks to humans and other environmental receptors when spent sands from iron, steel, and aluminum foundries are used in soil-related applications (e.g. manufactured soils) were determined. A complete risk assessment for use of spent foundry sands in soil-related applications was conducted in collaboration with U.S. EPA. This risk assessment is currently undergoing peer review. As a result of the risk assessment and the efforts of the American Foundry Society to use 50% of SFS by 2015, the foundry industry has the potential to save $200 million in disposal costs each year.
Risk assessment of spent foundry sands in soil-related applications. ARS scientists in Beltsville, Maryland in cooperation with scientists from Pennsylvania State University, Ohio State University, Purdue University, and Foundry Industry Recycle Starts Today developed a risk assessment that will provide states with sound scientific information needed to develop or to modify existing regulatory structures involving the beneficial use of spent foundry sands (SFS) in soil-related applications. Representative SFS from iron, steel, and aluminum foundries were analyzed for trace elements and other potential pollutants; effects of SFS on plants, earthworms, and soil microorganisms were measured. SFS contained metal concentrations that were below those found in the 95th percentile of native U.S. soils; metals in SFS did not move from the soil to plants or earthworms nor did they pose a toxicity risk to plants and earthworms. Concentrations of dioxins and dioxin-like compounds, pollutants of major concern due to their extreme toxicity, were also evaluated in SFS, and levels were found to be below those in agricultural and urban soils. In cooperation with U.S. EPA, a probabilistic risk assessment of multiple exposure pathways concluded that SFS do not comprise a lifetime risk for home gardeners using a manufactured soil containing SFS. Windblown dust from a soil blending facility and drainage water risks were also assessed and were found to not present an environmental risk. Overall, the risk assessment demonstrated that spent sands from iron, steel, and aluminum foundries can be safely used as an ingredient in manufactured soils and other soil-related applications without risk to human health or the environment.
Dungan, R.S. 2008. The characterization of trace metals and organics in spent foundry sands over a one-year period. Journal of Residuals Science & Technology. 5(3):111-125.
Dungan, R.S., Huwe, J.K., Chaney, R.L. 2009. Concentrations of PCDD/PCDFs and PCBs in spent foundry sands. Chemosphere. 75:1232-1235.
De Koff, J.P., Lee, B.D., Dungan, R.S. 2008. Amelioration of physical strength in waste foundry green sands for reuse as a soil amendment. Journal of Environmental Quality. 37:2332-2338.