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Title:

Interlaboratory Validation of the Leaching Environmental Assessment Framework (LEAF) Method 1313 and Method 1316

Document Type: Government Documents
Author:Garrabrants, A.C., D. Kosson, Stefanski L., R. DeLapp, P.F.A.B. Seignette, H.A. van der Sloot, P. Karither, and M. Baldwin.
Year:2012
Department:U.S. Environmental Protection Agency, Office of Research and Development,
City:Research Triangle Park, NC
Abstract:This document summarizes the results of an interlaboratory study conducted to generate precision estimates for two parallel batch leaching methods which are part of the Leaching Environmental Assessment Framework (LEAF) and are under review by the U.S. Environmental Protection Agency (EPA) Office of Solid Waste and Emergency Response for potential inclusion into the EPA’s Test Methods for Evaluating Solid Waste, Physical/Chemical Methods (SW-846).  Method 1313: Liquid-Solid Partitioning as a Function of Eluate pH using a Parallel Batch Extraction Procedure  Method 1316: Liquid-Solid Partitioning as a Function of Liquid-to-Solid Ratio using a Parallel Batch Extraction Procedure. For each of the two methods, the interlaboratory study targeted ten participating laboratories and three study materials – a coal combustion fly ash, a cementitious solidified waste analog, and a contaminated smelter site soil. Method precision was evaluated using repeatability relative standard deviation (RSDr) and reproducibility relative standard deviation (RSDR) of eluate concentrations obtained from the interlaboratory study. The mean repeatability were determined to be 13% RSDr for Method 1313 and 8% RSDr for Method 1316. This level of within-laboratory precision means that variation of test replicates from a single operator would be less than 13% for Method 1313 and 8% for Method 1316. Method repeatability was consistent with the repeatability found for a European standard (EN) single-batch extraction test, EN 12457-2. Mean method reproducibility was determined to be 28% RSDR for Method 1313 and 19% RSDR for Method 1316 indicating the potential variation in multi-laboratory results on the same material. Reproducibility precision was consistent with the reported median reproducibility estimate for EN 12457-2 and was considerably better than the mean reproducibility value reported for the EPA’s Toxicity Characteristic Leaching Procedure (TCLP; SW-846 Method 1311). In parallel to the validation of the LEAF methods, the study materials were tested by the Energy Research Centre of the Netherlands and DHI, Denmark using two European technical specification for pHdependence leaching currently in process of standardization through the Comité Européen de Normalisation (CEN). Although similar in structure and intent to Method 1313, these two tests differ from each other and from Method 1313 in the way that the final pH is achieved. Comparisons of the CEN test data to Method 1313 robust confidence limits showed that there is little to no operational difference in the pH-dependent leaching results from the three study materials. The findings of this study provide confidence that Method 1313 and Method 1316 provide the characteristic leaching behavior that is intended by the LEAF leaching methods with a high degree of precision.
Focus Area:Remediation, Near-Surface Disposal & Long Term Stewardship
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