New Leaching Environmental Assessment Framework (LEAF) Methods

The Leaching Environmental Assessment Framework (LEAF) is a leaching evaluation system, which consists of four leaching methods, data management tools, and scenario assessment approaches designed to work individually or to be integrated to provide a description of the release of inorganic constituents of potential concern (COPCs) for a wide range of solid materials. The LEAF methods have been designed to consider the effect of key environmental conditions and waste properties on leaching. The LEAF “How-To” Guide describes how the LEAF method results can be used to develop screening level assessments of constituent release or to develop more accurate estimates of release in specific use or disposal scenarios.

LEAF Methods and “How-To” Guide

Method 1313 is designed to evaluate the partitioning of constituents between liquid and solid phases at or near equilibrium conditions over a wide range of pH values. The method consists of 9-10 parallel batch extractions of solid material at various target pH values.

Method 1314 is a percolation column test designed to evaluate constituent releases from solid materials as a function of cumulative liquid-to-solid ratio. The method consists of a column packed with granular material with moderate compaction. Eluent is pumped up through the column to minimize air entrainment and preferential flow.

LEAF Method 1314

Method 1315 is a semi-dynamic tank leaching procedure used to determine the rate of mass transport from either monolithic materials (e.g., concrete materials, bricks, tiles) or compacted granular materials (e.g., soils, sediments, fly ash) as a function of time using deionized water as the leaching solution. The method consists of leaching a sample in a bath with periodic renewal of the leaching solution at specified cumulative leaching times.

Method 1316 is an equilibrium-based leaching test intended to provide eluate solutions over a range of liquid-to-solid ratios. This method consists of five parallel batch extractions of a particle-size-reduced solid material in reagent water over a range of liquid-to-solid ratios. At the end of the contact interval, the liquid and solid phases are separated for constituent analysis.

The purpose of the LEAF “How-To” Guide is to provide an understanding of the Leaching Environmental Assessment Framework to facilitate its broader use in environmental assessment. The guide provides background on the LEAF methods, how to perform the methods, and how to understand the method results. It also provides guidance on the application of LEAF to assess leaching potential of COPCs from solid waste materials for beneficial use, disposal, treatment, and remediation applications. In addition, the guide addresses frequently asked questions about the four LEAF methods, data management and reporting using freely-available software, and potential applications of the LEAF approach.

SW-846 Update VI – Phase III will be available for public comment until January 31, 2018. Comments can be submitted using the EPA Docket, ID# EPA-HQ-OLEM-2017-0210.

For questions about Update VI to SW-846 or submitting public comments, or to sign up for the SW-846 mailing list, please contact orcrSW846@epa.gov.