Use of the Leaching Environmental Assessment Framework (LEAF) for Evaluating Beneficial Use of Secondary Materials.

The Leaching Evaluation Assessment Framework (LEAF) is a set of four leaching test methods, data management tools, evolving coupled chemical speciation-based mass transfer models, and a decision framework that can be used for screening evaluation of beneficial uses for specific waste materials and detailed, site-specific assessment when warranted.  The goal of LEAF is to establish a tiered approach to leach testing and assessment that provides a common basis for estimating source terms for constituent leaching for a wide range of materials, engineered uses and disposal, and location-specific scenarios.   Joint, coordinated development of LEAF is occurring in the United States and the European Union.

The four LEAF leaching test methods include (i) pH dependent leaching, (ii) percolation column leaching, (iii) monolithic or compacted granular mass transfer rate, and (iv) batch liquid-to-solid (L/S) dependence leaching.  Validation of these four test methods was completed in 2012 and these methods  are currently being incorporated into USEPA SW-846 as Methods 1313, 1314, 1315 and 1316, respectively.  Analogous procedures to the LEAF methods as well as for soil specific parameters exist as technical specifications within the CEN/ISO methods framework.  Data management tools developed for use with the methods include method-specific data input templates and data management tool, LeachXS Lite™ (both freely available at http://vanderbilt.edu/leaching).  LeachXS Lite assists in the storage and comparison of data and allows for facilitated reporting through graphing and exporting capabilities. 

Results from the leaching test methods can be used directly for screening assessment purposes or used in conjunction with geochemical speciation and reactive mass transfer models for more detailed assessment of beneficial use and disposal scenarios.   In addition, compilations of material specific data sets, laboratory-to-field comparisons, and scenario models are being accomplished through USEPA and Department of Energy supported projects.