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Leaching Environmental Assessment Framework (LEAF) Methods and Guidance

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

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LEAF "How-To" Guide

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, guidance on how to perform the methods, and guidance on 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.

Beneficial Use

LEAF may be useful in estimating the environmental impacts from utilization of secondary materials, primarily as construction materials. Leaching data from LEAF or other relevant leaching tests can be used in EPA’s Methodology for Evaluating Beneficial Uses of Industrial Non-Hazardous Secondary Materials, which presents a voluntary approach for evaluating potential adverse impacts to human health and the environment from a wide range of industrial non-hazardous secondary materials and their associated beneficial uses. Prior to beneficially using secondary materials in any projects, interested individuals or organizations should consult with the relevant state and federal environmental agencies to ensure proposed uses are consistent with state and federal requirements.

Cleanups under CERCLA

LEAF may also find application in support of cleanup decisions under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) that address specific contaminants on a site-specific basis. The performance values against which LEAF would be evaluated may differ depending on the specific regulatory program involved. For example, site-specific data is used to determine whether action is warranted at a site. Furthermore, under CERCLA as stated in the National Oil and Hazardous Substances Pollution Contingency Plan, “levels generally should be attained throughout the contaminated plume, or at and beyond the waste management area when waste is left in place” (55 FR 8753, March 8, 1990). Decision-makers should consult with the appropriate regulatory agency to ensure compliance when using LEAF testing in support of an evaluation.

Under CERCLA, cleanup decisions depend on site-specific factors. General guidance on use of LEAF data that would be applicable to all sites is impractical and beyond the scope of the How-to Guide. As such, EPA expects to provide additional guidance on the use of LEAF for CERCLA response actions as experience with LEAF evolves.

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Frequent Questions about the LEAF Methods and "How-To" Guide

EPA has developed answers to frequently asked questions about the LEAF Methods and "How-To" Guide.

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LEAF Response to Public Comments

The public comment period for the LEAF methods and "How-To" Guide closed on January 31, 2018. Although submissions will no longer be accepted, the EPA Docket can be viewed by searching for ID# EPA-HQ-OLEM-2017-0210. EPA reviewed all comments and published a Response to Comments document along with the final versions of the methods and “How-To” Guide.

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Useful Resources

Data Management and Modeling Software

Agency Leaching Studies

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