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Assessing Risk Posed By Land Application Of Ash From The Combustion Of Wood And Tires
Citation:
TOLAYMAT, T. M., B. Dubey, AND T. TOWNSEND. Assessing Risk Posed By Land Application Of Ash From The Combustion Of Wood And Tires. P. B. Duncan (ed.), JOURNAL OF RESIDUALS SCIENCE AND TECHNOLOGY. DEStech Publications, Inc, Lancaster, PA, 5(2):61-75, (2008).
Impact/Purpose:
To conduct different tests to assess the risk posed by land application of ash from the combustion of wood and tires. To make several contributions valuable to those interested in the characterization and management of residuals such as ash.
Description:
The total and leachable metal concentrations in ash from the combustion of waste wood and vehicle tires (WT ash) were characterized. These data were then used to examine a variety of issues associated with determining whether the WT ash could be beneficially used outside of a landfill (e.g., land application as fill material, soil amendment). Metal release was assessed using standardized batch tests, lysimeter leaching tests, and additional leaching experiments targeting specific factors that impact metal leaching. The toxicity characteristic leaching procedure (TCLP) and the synthetic precipitation leaching procedure (SPLP) extracted similar metal concentrations. Although arsenic was detected at high concentrations in the WT ash totals analysis, it did not leach at concentrations that may pose a risk to human health and the environment. Another metal of potential concern with regard to groundwater contamination is lead. Lead leached from WT ash at 120, 55, 52, and 52 µg/L using the WET, TCLP, SPLP, and DI water extraction, respectively. Lead was also encountered in the lysimeter leachate above its groundwater cleanup target level (GWCTL). In terms of risk assessment, from a direct human exposure pathway, arsenic was found to be the most limiting element. Comparison with the leaching SCTLs indicated that arsenic, chromium, and zinc would pose a potential risk to groundwater. The SPLP results did not find these metals to pose a risk, but has lead concentrations above GWCTL suggesting that using leaching SCTLs that are developed for soil is not appropriate for application to combustion ash. When compared to steady-state concentrations measured in the lysimeters, SPLP, TCLP and DI water lead concentrations matched very well suggesting that these concentrations reflected the pore water concentration for this ash.
