WORKSHOP REPORT

Considerations for Developing 

Leaching Test Methods for Semi- and 

Non-Volatile Organic Compounds

United States Office of Research EPA 600-R-16-057

Environmental Protection and Development (E343-02) April 2016

Agency Office of Land and www.epa.gov/superfund

Emergency Management

(5102G)
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EPA/600/R-16/057

April 2016

WORKSHOP REPORT

CONSIDERATIONS FOR DEVELOPING 

LEACHING TEST METHODS FOR 

SEMI- AND NON-VOLATILE ORGANIC 

COMPOUNDS
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Workshop Report Table of Contents

TABLE OF CONTENTS

NOTICE/DISCLAIMER.......................................................................................................................................................... III

ACKNOWLEDGEMENTS.......................................................................................................................................................IV

ABBREVIATIONS AND ACRONYMS................................................................................................................................. IV

1. INTRODUCTION ....................................................................................................................................................... 1

2. PRESENTATIONS AND RELATED DISCUSSIONS........................................................................................ 3

2.1 Presentation: Key parameters or drivers that govern the source term at the 

unit boundary for subsurface leaching of semi- (SVOC) and non-volatile 

(NVOC) organic chemicals.................................................................................................................... 3

Discussion................................................................................................................................................... 4

2.2 What is our field test experience related to organics leaching?........................................... 5

Discussion................................................................................................................................................... 6

2.3 Estimation of Source Term Concentration for Organics Contained on 

Superfund Sites......................................................................................................................................... 6

Discussion................................................................................................................................................... 7

2.4 European and international standards on leaching of organic contaminants, 

available tools and recent developments for assessment of organic 

contaminants ............................................................................................................................................. 7

2.5 What is LEAF for inorganics? What lead to its development? What was the 

process and timeline for developing and validating the methods?...................................10

2.6 Existing Tools and Limitations to Address Leaching of Organic Species........................12

3. WORKSHOP DISCUSSION...................................................................................................................................16

3.1 Key Parameters that Drive Organics Leaching..........................................................................16

3.2 Important Considerations for Methods Development ...........................................................17

3.3 Considerations Related to Source Materials and Constituents of Concern....................18

3.4 Applicability of LEAF Methods .........................................................................................................20

Appendix A: Workshop Agenda 

Appendix B: Workshop Participants

Appendix C: Workshop Presentations

i 
Workshop Report Lists of Tables and Figures

LIST OF TABLES

Table 2-1. LEAF Methods Overview............................................................................................................................... 13

LIST OF FIGURES

Figure 2-1. Association of First Order Expressions to LEAF Leaching Tests................................................15

ii
Workshop Report Notice/Disclaimer

NOTICE/DISCLAIMER

The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development, 

funded the preparation of this report under EPA Contract No. EP-D-11-006. The Office of Resource 

Conservation and Recovery also provided funding for the workshop. This report was subjected to 

the Agency’s peer administrative review and is approved for publication as an EPA document. 

Statements captured in the discussion and summaries are those of the participants, not necessarily 

reflective of the EPA. Presentations are the responsibility of their authors and may represent 

opinions or personal points of view in some cases. Mention of trade names or commercial products 

does not constitute endorsement or recommendation for use.

iii
Workshop Report Acknowledgements

ACKNOWLEDGEMENTS 

Many people contributed their expertise to the development and implementation of this workshop,

and the preparation and review of this publication. This effort would not have been possible 

without the efforts of the USEPA and academic experts who participated in the workshop and 

assisted in the preparation of this report. The document was prepared for Susan Thorneloe of the 

Air Pollution Prevention and Control Division of the National Risk Management Research 

Laboratory of the USEPA Office of Research and Development under EPA Contract No. EP-D-11-006, 

Work Assignment No. 5-10. Co-authors and reviewers of the report include Susan Thorneloe, ORD; 

Linda Fiedler and Robin Anderson; Office of Superfund Remediation and Technology Innovation; 

and Greg Helms, Office of Resource Conservation and Recovery.

iv
Workshop Report Acknowledgements

FOREWORD

The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the 

Nation’s land, air, and water resources. Under a mandate of national environmental laws, the 

Agency strives to formulate and implement actions leading to a compatible balance between human 

activities and the ability of natural systems to support and nurture life. To meet this mandate, EPA’s 

research program is providing data and technical support for solving environmental problems 

today and building a science knowledge base necessary to manage our ecological resources wisely, 

understand how pollutants affect our health, and prevent or reduce environmental risks in the 

future.

The National Risk Management Research Laboratory (NRMRL) is the Agency’s center for 

investigation of technological and management approaches for preventing and reducing risks from 

pollution that threaten human health and the environment. The focus of the Laboratory’s research 

program is on methods (and their cost-effectiveness) for the prevention and control of pollution to 

air, land, water, and subsurface resources; protection of water quality in public water systems; 

remediation of contaminated sites, sediments and ground water; prevention and control of indoor 

air pollution; and restoration of ecosystems. NRMRL collaborates with both public and private 

sector partners to foster technologies that reduce the cost of compliance and in order to 

identify/anticipate emerging problems. NRMRL’s research provides solutions to environmental 

problems by: developing and promoting technologies that protect and improve the environment; 

advancing scientific and engineering information to support regulatory and policy decisions; and 

providing the technical support and information transfer to ensure implementation of 

environmental regulations and strategies at the national, state, and community levels.

This publication has been produced as part of the Laboratory’s strategic long-term research plan. It 

is published and made available by EPA’s Office of Research and Development (ORD) to assist the 

user community and to link researchers with their clients.

Cynthia Sonich-Mullin, Director

National Risk Management Research Laboratory

Office of Research and Development

U.S. Environmental Protection Agency

v 
Workshop Report Abbreviations and Acronyms

ABBREVIATIONS AND ACRONYMS

COC

DNAPL

DOC

DOM

EPA

ERG

EU

ISO

ISS

LEAF

L/S

LSP

MCL 

MGP

MSW 

NAPL

NRMRL

NVOC

ORCR

ORD

OSRTI

PAH

PCB

PTFE

RCRA

SPLP

SVOC

TCLP

UVA

VOC

Contaminants of Concern

Dense Non-Aqueous Phase Liquid

Dissolved Organic Carbon

Dissolved Organic Matter

Environmental Protection Agency

Eastern Research Group

European Union

International Organization for Standardization

In Situ Solidification/Stabilization

Leaching Environmental Assessment Framework

Liquid/Solid

Liquid Solid Partitioning

Maximum Contaminant Level

Manufactured Gas Plant

Municipal Solid Waste

Non-Aqueous Phase Liquid

National Risk Management Research Laboratory

Non-Volatile Organic Chemical

Office of Resource Conservation and Recovery

Office of Research and Development

Office of Superfund Remediation and Technology Innovation 

Polycyclic Aromatic Hydrocarbon

Polychlorinated Biphenyl

Polytetrafluoroethylene 

Resource Conservation and Recovery Act

Synthetic Precipitation Leaching Procedure (EPA Method 1312)

Semi-Volatile Organic Chemical

Toxicity Characteristic Leaching Procedure (EPA Method 1311)

University of Virginia

Volatile Organic Chemical

vi
Workshop Report Introduction

1. INTRODUCTION

The workshop was hosted by the US Environmental Protection Agency (EPA) on September 16 and 

17, 2015 in Arlington, VA to discuss developing leaching test methods for semi- and non-volatile 

organic compounds. The purpose of the workshop was to exchange information concerning how to 

evaluate the potential for release of semi- or non-volatile organic constituents at contaminated 

sites where sub-surface treatment approaches have been applied to control migration, and from 

waste that is disposed or re-used. The workshop also considered how to predict sub-surface 

leaching potential at the outer edge of the treated media, or in disposal or material re-use 

situations, at the unit or use boundary. Representatives from EPA and academia participated in the 

workshop. Workshop discussions focused on identifying technical issues for further consideration 

to support the development of tools that could be used to make determinations of protectiveness 

and regulatory compliance. 

Representatives from the Office of Resource Conservation and Recovery (ORCR) and the Office of 

Superfund Remediation and Technology Innovation (OSRTI) identified several workshop 

objectives, including: 

• Identify key parameters expected to govern leaching potential of semi- and/or non-volatile

organic constituents from sub-surface treated media (e.g., soils) or disposed waste. The

keys parameters will need to be considered in the development of leaching tests to provide

more accurate source-term data that inform treatment and waste disposal decisions;

• Understand how to account for these parameters when evaluating release potential both at

initial treatment and over time (in general, 50-100 years);

• Identify methodologies currently used to evaluate organic constituent leaching and their

strengths and weaknesses;

• Understand whether the Leaching Environmental Assessment Framework (LEAF)

established for inorganics can be adapted to evaluate leaching of organic constituents; and

• Explore how to leverage the best science available to facilitate decision-making.

During the workshop, the following key points related to Superfund site remediation were 

discussed to help frame workshop discussions: 

• Treatment effectiveness is measured at the waste management area boundary;

• Clean-up levels are assumed to be known;

• Superfund generally deals with site-specific data and information rather than generic or

national distributions of modeled fate and transport scenarios; and

• In situ treatment technologies most often used to treat organic contaminants in soil include

soil vapor extraction for volatile organic chemicals (VOCs) and in situ

solidification/stabilization (ISS) for semi-volatile organic chemicals (SVOCs) and nonvolatile organic chemicals (NVOCs).

After the introductory remarks, there were a series of technical presentations followed by related 

technical discussions. The information from each presentation is summarized in the remainder of 

this report. The report also includes the three appendices listed below. 

1 
Workshop Report Introduction

• Appendix C – Contains the presentations.

2 

• Appendix A – Presents the workshop agenda,

• Appendix B – Provides a list of the meeting participants, and
Workshop Report Presentations and Related Discussions 

2. PRESENTATIONS AND RELATED DISCUSSIONS

As described in the agenda found in Appendix A, the workshop included a series of presentations. 

The key points from each presentation are below including summary points from the group 

discussion that followed each presentation.

2.1 Presentation: Key parameters or drivers that govern the source term at the unit boundary for 

subsurface leaching of semi- (SVOC) and non-volatile (NVOC) organic chemicals

Key points from Dr. Charles Werth’s (University of Texas – Austin) presentation: 

• Factors that either retard or enhance leaching of semi- and non-volatile organics can

include:

— Adsorption/desorption;

— Multi-phase partitioning; and

— Equilibrium vs. diffusion controlled release.

• Complex matrices that influence leaching include natural components of soils, sorption

amendments to sequester pollutants, and precipitates that encapsulate pollutants..

• Leaching is controlled by the capacity of the different phases for the organic chemical(s) of

interest, and the mass transfer rate from each phase. As water moves through a phase, the

solute goes through advection and dispersion; each phase holds some of the solute (water,

non-aqueous phase liquids (NAPL) – organic or a mixture, and solid), which accumulate in

the phases.

• It is possible to approximate leaching from sorbed and NAPL phases with a first order

expression to illustrate dependence on the capacity of each phase for pollutant and mass

transfer rate constant.

• The air phase holds little volatile organic chemicals (VOCs), semi-volatile organic chemicals

(SVOCs) or non-volatile organic chemicals (NVOCs) relative to solid and NAPL phases and

contributes little to leaching.

• As is it replenished, the water phase represents leachate and serves as a pollutant sink for

other phase. The by presence of salts, co-solvents, dissolved organic matter (DOM), and

colloids affects the capacity of the water phase.

— Increasing ionic strength decreases the aqueous solubility;

 Altered solubility is related to concentration of the salt

 As the salt concentration increases, solubility decreases (lowers the capacity of the

water)

— Increasing co-solvent concentration increases the aqueous solubility (e.g., methanol –

changes the structure of the water and increases the capacity of water to hold a solute); 

and

— Increasing DOM concentration increases the apparent aqueous solubility (or association

with macromolecules).

• Leaching capacity of soils and sediments depends on soil/sediment properties and

chemical properties. Soils, sediments, and geosorbent amendments (e.g., char) can sorb

large amounts of VOCs, SVOCs and NVOCs, and slowly release them.

3 
Workshop Report Presentations and Related Discussions 

— Equilibrium capacity of these solids is determined by composition;

— There are both absorption (or partitioning) and adsorption environments; and

 The capacity of the soil partitioning environment for contaminants in absorption

environments can be estimated and is often linear

 Adsorption environments are more challenging to characterize, and it is impossible

to predict adsorption; therefore, empirical models are often used

 The capacity of adsorption environments for contaminants must be measured; the

relationship between water and soil concentrations is typically nonlinear

— Both partitioning and adsorption environments are often present in solids, and the

contribution of partitioning and adsorption environments varies widely depending on 

the sorbent. 

• Mass transfer processes can be complex and occur in parallel or in series.

• A simplified model that focuses on multi-phase partitioning and adsorption is needed to

predict mass transfer rates.

Discussion

• Consider each phase and identify the capacity and subsequent mass transfer rate.

— Capacity is relative to the solubility in water (high capacity = 1000x or more soluble in

water); and

— Mass transfer rate measured as velocity of leaching in a column (cm/min).

 Fast = equilibrium

 Medium = minutes to hour to days

 Slow = many days to weeks/months

 Very slow = years

• Cement amendments can be in block or granular form and the format can affect the

diffusion length scale (a measure of how far the concentration has propagated over time).

— Diffusion coefficient affects the time scale and can be challenging to predict (e.g., if a

contaminant is trapped throughout the cement, the length scale is unknown);

— For ISS with equal distribution of NAPL, expect fairly short length scales; and

— For ISS with macro-encapsulation (boundary has no NAPL), expect very long length

scales.

• The manufactured gas plant (MGP) industry is adding activated carbon to reduce leaching,

and there are questions regarding whether the added components are improving

performance.

• An important consideration related to mass transfer is the degree of mixing and conformity

for laboratory prepared mixes compared to the long-term effects of actual treated materials

observed in the field.

• Unmixed regions may dominate field results.

• The age of NAPL and its duration of contact to soil can influence the rate of leaching of

organic constituents.

4 
Workshop Report Presentations and Related Discussions 

• Adding adsorption materials to dilute the concentration of contaminated particles can

create another environment whereby new added capacity delays or slows leaching

(increasing the length scale slows overall mass transfer rate).

• Participants discussed ISS conditions that are below the water table. As the water table rises

and falls, pore spaces are occupied and emptied thereby changing the connectivity of space

in the different phases.

— VOC transport through gas phase can be fast (i.e., would have a large impact on the rate

at which VOC would leave); and

— Mass transfer of SVOCs in NAPLs would slow when water table goes down and increase

again when water table re-rises back.

• Participants identified the following key considerations and questions for future work:

— The capacity and mass transfer rate constants for each phase determine the relative

contributions to leaching;

— Consider and evaluate competing mechanisms when developing a framework to assess

leaching;

— Consider the conditions and integrity of materials over time (e.g., carbonation of weak

cementitious material can influence product stability over time);

— Simulation of the age of material can be an important factor;

— Account for time scales – test at various states (initial, six months, accelerated aging);

 Relate time scales of mass release to controlling process to design an experiment

and interpret release/risk

— Conduct background research to better understand mixing issues and how to account

for differences between laboratory and field conditions (i.e., represent the potential for 

incomplete mixing and lack of mixing in the field);

— Identify uncertainties that exist between laboratory and field conditions; and

— Consider external factors (environmental conditions) that influence the integrity of

materials (e.g., organoclays).

2.2 What is our field test experience related to organics leaching?

Key points from Dr. Craig Benson’s (University of Virginia) presentation: 

• Dr. Benson discussed his experiences relating barrier experiments in the laboratory to the

field.

• He underscored the importance of understanding how the subtleties of experimental design

components can dramatically influence results and predictive outcomes.

• Several key issues to consider when designing experimental protocols include:

— Account for biological processes and activity of a system when designing experiments;

— When running long-term experiments with small amounts of mass, pay significant

attention to experimental design and apparatus – measure and conduct experiments on 

design components;

— When dealing with small amounts of mass, exercise caution in the quantity of liquid to

extract when sampling to avoid impact on mass transport processes;

5 
Workshop Report Presentations and Related Discussions 

— Experimental apparatus can have a significant effect on outcome of transport

experiments with hydrophobic organic contaminants at low concentrations;

— Evaluate materials beforehand as sinks for organic contaminants, even in the most

obscure components, to avoid false negatives;

— Evaluate apparatus for unintended sinks for organic contaminants (e.g., O-ring);

— Develop expectations for outcomes of experiments to provide a reality check on data;

— Accurately model the breakthrough time using simple analytical methods to bracket

expected boundaries; 

— Recognize the importance of quality control (positive and negative) and method blanks;

and

— Understand what you expect to see and measure why you do not.

Discussion

• Dr. Benson reiterated the potential importance of the relationship and influence of

dissolved organic carbon (DOC) in experimental design following the discussion of DOM

binding in Dr. Werth’s talk.

— Specifically, how DOC impacts binding and whether the mobility of contaminants would

increase when using real groundwater with DOC over deionized water often used in the 

laboratory. 

2.3 Estimation of Source Term Concentration for Organics Contained on Superfund Sites

Key points from Dr. Ed Barth’s (EPA/ORD/NRMRL) presentation: 

• Dr. Barth discussed some of the challenges EPA Regions face in providing a quick answer for

evaluating “the source term at the waste management area” for remedies involving ISS of

organic materials (including dense non-aqueous phase liquid [DNAPLs]).

• Dr. Barth discussed a variety of methods for pre-placement and post-placement evaluations.

He indicated that EPA and other organizations have guidance for the evaluation of ISS for

organics, but questioned whether there is too much emphasis on physical properties (UCS,

hydraulic conductivity) and not enough emphasis on chemical bonding strength and

leaching mechanisms, especially if free product is present on the site and if colloids are

present in the site around water.

• He described one approach to evaluate barrier improvements with an emphasis on

organoclays or activated carbon. Specifically, the focus would be to: (1) evaluate the

bonding strength of activated carbon and organoclay, and (2) determine whether colloids

interfere with bonding strength.

• Additional experimental design considerations specific to polycyclic aromatic hydrocarbons

(PAHs), analytical techniques, and data interpretation techniques should include:

— Reduction of PAHs in laboratory samples due to photochemical oxidation exposure;

— Headspace volatilization;

— Dilution;

— Sorption onto glassware; and

— Oil sheens on sample surface.

6 
Workshop Report Presentations and Related Discussions 

• Historical and current laboratory approaches (evaluated by EPA and being proposed by

EPA regional contractors) that EPA Regions use to assess adequacy of

treatment/containment processes include:

— Application of a modification to the LEAF Method 1315;

— Use of site groundwater;

— Use of coated glassware;

— Partitioning/NAPL saturation; and

— Use of pore water models based upon partitioning.

Discussion

• Summary points discussed:

— Some EPA Regional Offices have used leaching methods, beyond the toxicity

characteristic leaching procedure (TCLP), to ascertain whether a 

treatment/containment process is either adequate to protect the public health and 

environment or as a comparison to other treatment technologies; 

— An array of challenge fluids is available to cover the range of extraction recovery; and

— While bonding-strength indicator methods are available, they are rarely used in

treatment evaluations.

• More guidance is required if EPA Regions are beginning to use a modification to LEAF

Method 1315 to determine organic leaching.

• TCLP remains the regulatory standard for RCRA hazardous waste determinations and land

disposal restrictions requirements and is widely used for ISS effectiveness determination.

2.4 European and international standards on leaching of organic contaminants, available tools 

and recent developments for assessment of organic contaminants

Key points from Hans van der Sloot’s (Consultant – retired from the Energy Research Center of the 

Netherlands) presentation: 

• Dr. van der Sloot provided an understanding of leaching methods currently in use and the

status of standardization and validation in Europe.

• European standardization is split into different fields (soil, waste, mining waste, and

construction products) and methods that may be field-specific. Many fields have boundaries

that are interrelated and therefore, regulators are questioning whether methods need to be

harmonized across fields to promote standardization.

• Dr. van der Sloot described parameter differences and adaptations among methods for

organics and inorganics and noted many similarities.

• In response to earlier discussions on important parameters, Dr. van der Sloot noted:

— Bioactivity/biodegradation is not addressed during the test itself, rather it is dealt with

during sample preparation and storage; and

— Address aging by testing at various states (initial, six months, accelerated aging), rather

than designing for aging within the leaching test method itself.

7 
Workshop Report Presentations and Related Discussions 

• Important considerations identified through observations from European Union (EU)

standardization activities for leaching standards for organics include:

— The fundamental processes that characterize release behavior are not different, and in

many cases information on both organic and inorganic substances is needed; and

— Material requirements for the equipment and other parts contacting the eluate are

adapted to meet requirements for both types of substances.

 Glass column and stainless steel connections

 In the column, quartz sand or glass beads are used instead of filters

 It was noted that filtration commonly used for inorganic substances is unsuitable for

organic substances – if needed, centrifugation is recommended

• Dr. van der Sloot also noted the importance of the relationship of organics leaching to DOC

and complexation with DOC. He has observed an apparent correlation of PAH with DOC,

hence, indirect pH dependence of PAH leaching. This observation further underscores the

need to understand differing field conditions with the influence of DOC, where increased

DOC can increase leaching potential.

• Dr. van der Sloot summarized important take-away messages from the EU experience

developing methods for organics:

— Adsorption to Material Surfaces

 Match contacting surfaces to organic substances of interest

○ Do not use plastics (including Viton), rubber, polytetrafluoroethylene (PTFE)

(PAHs adsorb to Teflon)

○ Glass, stainless steel preferable

— Volatilization

 VOCs are not considered; only semi- and non-volatile organic substances are

considered

— Colloid Formation

 Because there is more colloid formation in a batch test compared to a column test,

centrifuge eluate rather than use filtration, if at all needed

— Eluate Analysis

 Always measure pH and DOC; DOC varies as a function of pH and hence water

insoluble organics associated with DOC have increased leachability as pH increases

— Demonstrated Higher Release Values from Batch vs. Column Tests

 Observations made during the development of International Organization for

Standardization (ISO) standards for soil show batch tests resulted in higher release 

values in almost all cases due to higher turbidity and thus higher DOC levels in batch 

compared to column

— Filtration and/or Centrifugation

 In the German test, filtration and centrifugation are not used when the turbidity of

the solution is below a certain value

8 
Workshop Report Presentations and Related Discussions 

• Additional key concepts that should be considered include:

— Liquid-solid partitioning;

 pH – indirectly relevant due to dependence of DOC on pH

 Liquid-solid ratio

 Redox – not directly relevant

 Dissolution/sorption

 Particulate and DOM interaction

 Eluate Chemistry

— Mass transport; and

 Diffusivity

 Surface area

 Surface interactions (local equilibrium)

— Limitations.

 Degradation of organic substances (after results are available, happens in the

analysis)

 Degradation of organic matter and associated DOC formation (time-lapsed issue)

 Sorption on many surfaces

 Volatilization

• Important observations were shared, including:

— Use of a common leaching conceptual framework and related standardized test methods

will allow for comparability of results across contaminants, sources of contaminated 

materials, scenarios and regulatory jurisdictions. 

— Standardized tests show systematic release patterns for organic contaminants to

further understanding of release mechanisms;

— Methods are aimed to simultaneously address both inorganic and organic substances to

facilitate ecotoxicity testing of eluates;

— Dissolved organic matter plays an important role in release of semi- and non-volatile

organic substances due to their association with DOC;

— Transport properties are controlled by the substance itself and by the transport

properties of DOC;

— The pH dependence of DOC release is important because the association of organics

with DOC impacts organics partitioning and transport;

— Release of organic substances from monolithic products (e.g., stabilized waste and

treated wood) is, primarily controlled by the release of DOC-bound organic substances 

and thus controlled by DOC release. DOC release from porous monolithic materials is 

about a factor 10 – 15 times slower than the release of soluble salts (e.g. Na+, K+, Cl-);

— DOC-associated organic substances are not bioavailable for a range of organisms

currently applied in ecotoxicity testing and thus have no toxic response;

— Partitioning of DOM in sub-fractions (fulvic and humic substances) may prove

important, in view of their different binding characteristics for organic contaminants; 

and

— The use of soil adsorption coefficient (Koc) parameters allows the partitioning of

organic contaminants to be estimated between particulate and DOM. 

9 
Workshop Report Presentations and Related Discussions 

• There were no tests have addressed specifications for leaching water (i.e., specifications for

pH and DOC) and therefore underscores the importance of a pH dependence test to

understand the impacts.

2.5 What is LEAF for inorganics? What lead to its development? What was the process and

timeline for developing and validating the methods?

Key points from Greg Helms’ (EPA/ORCR) and Susan Thorneloe’s (EPA/ORD/NRMRL) 

presentations: 

• Greg Helms provided an overview of LEAF for inorganics, what led to its development and

the process and timeline for developing and validating the methods.

• The TCLP is a generic leaching test representing an eluant pH = 4.98 (that of active decay

phase in a municipal solid waste [MSW] landfill); TCLP is broadly used and in many cases

inappropriately applied (e.g., at conditions not representative of the pH).

• Given the deficiencies and challenges of TCLP, EPA was urged to evaluate other more

representative methods to estimate and predict leaching that provide a better

representation of what is likely to occur.

• LEAF methods have broad applicability across materials and enable one to compare:

— pH;

— Liquid-to-solid (L/S) ratio; and

— Particle size.

• LEAF results can be very useful when you gain economies of scale when analyzing waste

management and re-use options for large quantities of waste.

Susan Thorneloe provided background on the importance of establishing methods that provided a 

more accurate depiction of leaching based on a range of environmental conditions. There was a 

need to have a more holistic understanding of the impact of air pollution control technologies at 

coal-fired power plants to ensure pollutant transfers were not delayed or shifted from one media

into another. Acros the U.S., coal-fired power plants were implementing wider spread use of air 

pollution control technology such as the use of selective catalytic reduction for post-combustion 

NOx removal, electrostatic precipitators or fabric filters for particulate capture, sorbent injection 

for increasing mercury control, and flue gas desulfurization or other scrubber technologies to 

reduce acidic gases in the stack emissions. When these pollutants are transferred from the air stack 

at coal-fired power plants to the fly ash and other air pollution control residues, the concern is 

whether the pollutants may be later released when the air pollution control residues are utilized for 

beneficial use or land disposed. [Thorneloe S.A., D.S. Kosson, F. Sanchez, A.C. Garrabrants and G. 

Helms (2010) “Evaluating the fate of metals in air pollution control residues from coal-fired power 

plants,” Environmental Science and Technology, 44, 7351-7356.] •

• LEAF is a collection of:

— Four leaching methods;

— Data management tools;

— Geochemical speciation and mass transfer modeling;

— Quality assurance/quality control; and

10
Workshop Report Presentations and Related Discussions 

— Integrated leaching assessment approaches.

• LEAF is designed to identify characteristic leaching behaviors for a wide range of materials

and associated use and disposal scenarios to generate material- and site-specific source

terms.

• LEAF is not a replacement for TCLP but instead is used when TCLP is not considered

applicable or appropriate. Uses include:

— Assess materials for beneficial use;

— Evaluate treatment effectiveness (equivalent treatment determination);

— Characterize potential release from high-volume materials; and

— Corrective action (remediation decisions).

• LEAF provides a source term for future modeling and facilitates comparing data across

materials when using a common framework.

• LEAF includes data management tools to facilitate implementation, including:

— Spreadsheets to help manage data and pre-calculate required values (e.g., titration);

— Form upload to the materials database; and

— Software for processing and results visualization.

• Susan shared important lessons learned through the LEAF development, including:

— Modifications to Methods 1313 and 1316;

 Tolerance for contact time was added

 Requirement that pH values be measured within one hour after separation of solids

and liquids due to lack of buffering in aqueous samples

— Modifications to Data Templates; and

 Mandatory information is highlighted

 Instructions more closely follow method text

— Other Considerations.

 Calibration of pH meters should cover entire pH range to extent possible

 Reagents should be freshly prepared, stored in vessels of compatible materials (e.g.,

strong alkalis not be stored in borosilicate glass)

 Laboratories should establish a QC regimen to check the quality of reagent water

(method blanks are important)

• Susan discussed lessons learned from the validation effort and suggested the following:

— Engage laboratories and ensure they follow the instructions;

— Brief participating laboratories through interactive webinars;

— Walk participating laboratories step-by-step through the process;

— Conduct methods training;

— Conduct QA/QC; and

— Ensure conformance to the method.

11
Workshop Report Presentations and Related Discussions 

2.6 Existing Tools and Limitations to Address Leaching of Organic Species

Key points from Dr. David Kosson’s (Vanderbilt University) presentation: 

• Dr. Kosson described the capabilities of existing leach test methods to measure factors that

impact organic leaching.

• Dr. Kosson provided an overview of leaching control factors, including chemical factors and

physical factors, coupled with release mechanisms of wash off, dissolution and diffusion.

• The distinction between simulation-based and characterization-based leaching approaches

was discussed:

— Simulation-based Leaching Approaches:

 Designed to provide representative leachate under specified conditions, simulating

a specific field scenario

 Eluate concentration assumed to be leachate (source term) concentration

 Simple implementation (e.g., single-batch methods like TCLP or Synthetic

Precipitation Leaching Procedure [SPLP]) and interpretation (e.g., acceptance

criteria)

 Limitations

○ Lack of Representativeness of testing to actual disposal or use conditions

○ Results cannot be extended to scenarios that differ from simulated conditions

○ Basis for comparison of results from different materials is often unclear

— Characterization-based Leaching Approach:

 Evaluate intrinsic leaching parameters under broad range of conditions

 More complex; sometimes requiring multiple leaching tests

 Results can be used to conduct “what if” analyses of disposal or use scenarios

 Provides a common basis for comparison across materials and scenarios

 Materials testing databases allow for initial screening

• Dr. Kosson provided an overview of existing methods in practice and identified limitations

for organic contaminants.

• LEAF methods were discussed, including the rationale and limitations for use with organics:

12
Workshop Report Presentations and Related Discussions 

Table 2-1. LEAF Methods Overview

Method Rationale Limitations for Use with Organics

1313

• Designed to provide Availability and

Liquid-Solid Partitioning (LSP) as a

function of pH. Also provides acid/base

titration and basis for chemical

speciation modeling

• Focus on end-state conditions (pH, L/S,

DOC, etc.)

• Particle size and contact intervals,

mixing to approach equilibrium

• Conceptual paradigm is applicable for

organic species

• Availability determination approach not

applicable for organics although some organic

constituents or fractions thereof partition

strongly to natural organic matter or NAPLs,

resulting in a very readily available fraction for

leaching and a more slowly or recalcitrant

fraction for leaching.

• pH domain beyond the relevant scenario pH not

needed

• Eluent and mixing conditions do not address

potential for deflocculation and colloid formation

(column test minimizes inadvertent release of

DOC; can get higher results from batch testing vs

column)

• Provisions for selection of apparatus materials,

filtration, sample mass, extraction volumes,

minimizing volatilization losses are not provided

• Many methods do not provide sufficient guidance

on what is “applicable”

1314

• Designed to provide LSP as a function of

L/S (elution curve). Approximates initial

pore water and linkages between

individual species leaching (e.g., DOC &

chloride complexation, depletion of one

species leading to increased release of

another)

• Particle size, dimensions, flow rate, to

approach equilibrium. Eluent to avoid

deflocculation

• Conceptual paradigm is applicable for

organic species

• Availability determination approach not applicable 

for organics; percolation column approach can be

used to indicate readily leachable fraction of

organic contaminants but also must be sensitive to

leaching kinetics.

• pH domain beyond the relevant scenario pH not

needed

• Eluent and mixing conditions do not address

potential for deflocculation and colloid formation

(column test minimizes inadvertent release of

DOC; can get higher results from batch testing

compared to column)

• Provisions for selection of apparatus materials,

filtration, sample mass, extraction volumes,

minimizing volatilization losses are not provided

• Many methods do not provide sufficient guidance

on what is “applicable”

13
Workshop Report Presentations and Related Discussions 

Table 2-1. LEAF Methods Overview

Method Rationale Limitations for Use with Organics

1315

• Designed to provide maximum release

flux (mass transport rate) by maintaining

dilute boundary condition

• Closed vessels to minimize atmospheric

exchange (CO2, O2)

• Interpretation includes consideration of

field scenario boundary conditions

• Conceptual paradigm is applicable for

organic species

• Provision for in-situ solid phase extraction not

provided (variants have been developed but not

standardized)

• Provisions for selection of apparatus materials,

filtration, sample mass, extraction volumes,

minimizing volatilization losses are not provided

1316

• Designed to provide LSP as a function of

0.5 ≤ L/S ≤ 10 mL/g dry material.

Provides basis to approximate early

leachate concentrations and

determination of availability or solubility

controlled leaching

• Particle size and contact intervals,

mixing to approach equilibrium

• Conceptual paradigm is applicable for

organic species

• Eluent and mixing conditions do not address

potential for deflocculation and colloid formation

resulting in a potential bias towards higher release

estimates.

• Provisions for selection of apparatus materials,

filtration, sample mass, extraction volumes,

minimizing volatilization losses are not provided

• Key take-aways from Dr. Kosson’s presentation include:

— Measurement of intrinsic leaching characteristics and development of source terms

based on mass balance, thermodynamic and mass transport principles provides a 

robust leaching assessment framework that is applicable to both inorganic and organic 

species; 

— Numerical modeling may be warranted when direct extension of laboratory results to

field conditions is not applicable and analytical solutions are not available; 

— A tiered approach to source term estimation provides for a balance between extent of

testing, complexity of source term development, and end-user needs, thus allowing 

users to assess the costs associated with specific tests compared to the benefits gained 

based on their needs; 

— Current LEAF test methods do not include specifications specific to many classes of

organic species; and

— Important factors that are not addressed specifically for organics include:

 Selection of apparatus materials, filtration, sample mass, extraction volumes,

minimizing volatilization losses, maintaining “dilute” boundary conditions (for 

monoliths)

 Use in source terms does not address NAPLs and vapor phase transport

14
Workshop Report Presentations and Related Discussions 

Discussion

• The LEAF framework allows you to run computational what-if scenarios.

• It is important to understand the difference between exposure conditions and field

conditions and make the appropriate modifications.

• As shown in the figure below, Dr. Kosson was able to relate the first order reaction equation

addressed in Dr. Werth’s talk that identifies key drivers with elements of LEAF methods

that permit measurement of key components to predict leaching of organics. LEAF leaching

test methods are designed to measure the available content, liquid-solid partitioning and

mass transfer rates to facilitate development of scenario-specific leaching source terms.

Figure 2-1. Association of First Order Expressions to LEAF Leaching Tests

• There is a need to make the jump to practical implementation, recognizing constraints and

coming to a reasonable compromise.

• Understanding pH dependence is important given that there may be situations where the

pH could shift over time and therefore influence leachability (e.g., if there is a breakdown of

organic matter in capped material and subsequent influx of dissolved organic matter

capable of mobilizing organics). Changes in pH also may occur in response to biological

processes.

15
Workshop Report Workshop Discussion

3. WORKSHOP DISCUSSION

Additional discussion followed the conclusion of presentations and continued through the morning 

of Day 2. Discussion topics are summarized below and are organized by related topics.

3.1 Key Parameters that Drive Organics Leaching

• In measuring organic leaching, two systems are in effect: 1) a percolation system and 2) a

diffusion system.

• There are many factors to consider, not all of which are always a concern; therefore, there is

a need to identify the most important factors.

• Participants described external field considerations to consider when designing an organics

leaching test:

— Presence of a discrete organic phase;

— Presence of SVOCs and VOCs;

— Physical form of the material;

— Groundwater velocity;

— Water quality/composition;

 DOC, which may vary seasonally

 Ionic strength

 pH

— Bioavailability of study material;

— Depth to groundwater;

— Temperature;

 Reasonably translating temperature fluctuations (laboratory vs. field)

 Controlled conditions

— Weathering may be a factor depending geographic location and whether waste is

located above freeze-thaw line; 

 Diffusion

 Extent of mixing/homogeneity

 Durability testing

 Diffusion changes based on degradation in material

 Climate change factors, for example, seawater intrusion

— Sampling to control microbial variables;

 Representative and compositing sample collection; and

 Consider whether remediation treatment itself could affect other areas of site (e.g.,

by changing the pH or adding DOC).

• Participants described analytical parameters that impact leaching of organic constituents:

— pH;

— Temperature;

— Physical size and form of the material (granular or monolithic), which affects mass

transport distances; 

— L/S or water contact time, velocity, and volume;

16
Workshop Report Workshop Discussion

— Composition of water used in testing;

 Ionic strength

 DOC

— Test type: batch, column, or monolith;

— Laboratory equipment compatibility and degradation (steel, coated glass, maybe

Teflon); 

 Scale of apparatus

 Preservation to prevent degradation

— Local equilibrium;

— Eluate composition;

— Age of sample;

 90 day maximum age

— Scale of apparatus;

— Laboratory equipment suitable for testing organics;

— Testing over time, to capture constituents that increase in solubility over time;

 Design the leaching test to inform the decision maker about whether

solidification/stabilization is an appropriate treatment 

— Location of material relative to boundary; and

— Comparability of leaching test result with the analogous analytical test method (solid

extraction). 

• Other potentially problematic or confounding leaching factors include:

— Reducing conditions cause chlorinated compounds to leach first;

— Treatment may change diffusion behavior; and

— Oily wastes present a challenge to evaluate because of physical constraints of the testing

equipment and difficulties in interpreting the results. 

3.2 Important Considerations for Methods Development

• Through the presentations, participants gained a better understanding about the

fundamental mechanisms that affect the release of organics. The challenge now is to identify

key drivers, balancing practicality and costs, while remaining scientifically defensible. A

framework considering a phased or tiered approach may be appropriate to handle a broad

range of waste materials.

• Participants expressed a desire to simplify the system, identify key parameters, and

translate components into a first order reaction.

• The following questions are important to consider related to implementing an evaluationbased approach using both modeling and testing:

— How much modeling?

— How much leach testing?

— Are we addressing materials evaluation?

— Can modeling to isolate variability be developed?

• A participant noted that if a batch equilibrium test was conducted, one could run the test

where the concentration in water was close to zero to permit the calculation of maximum

flux out when the driving force concentration is known. One can relate max flux out to

17
Workshop Report Workshop Discussion

calculate water out (percolation rate) to compare against a maximum contaminant level

(MCL) (by transforming the first order rate equation to solve for MCL).

— Only the bulk measurement is needed to understand the percolation rate

• A step function could be an input for comparative assessment (i.e., current state, remediated

state or measure of treatment effectiveness).

• The difference of results between batch and flow-through systems was discussed and when

to use each.

— Column tests provide a practical dilution curve

— Batch tests provide an indication for bounding modeling conditions and provide a worst

case scenario where if concentrations are below regulatory thresholds there is no need 

to test further

• The following issues are related to organic leaching and leach testing:

— Mobility of NAPL

— Impact of mixing

— Durability of treatment technology

— Effective compliance monitoring at sites to assess treatment effectiveness

— Quality assurance and quality control protocols to measure whether what was built was

as designed

— Performance specifications for ISS

— Uniformity of solidification/stabilization amendment mixing)

• Other considerations related to test specifications:

— An opportunity exists to modify existing methods to address material and head space

requirements to meet the needs for both inorganic and organic substances whereby a 

single method could exist that addresses any required protocol deviations that may be 

substance-specific 

— Requirements for leaching tests and analytical techniques can be collectively addressed

if a larger system is designed or a wider column is used

— Cleanup levels with very low detection levels will require large volumes of waste

material to adequately assess

— In partitioning testing, it may be necessary to measure DOC in solid and aqueous phase

as DOC will vary in different environments

— If material contains a high levels of DOC (e.g., from natural organic matter), testing

results will likely result in increases in mobility of organic compounds.

3.3 Considerations Related to Source Materials and Constituents of Concern

• Participants discussed how NAPLs will initially dominate phases, followed by partitioning

environments, and then adsorption environments.

— It is possible to flush the system or conduct an extraction to isolate NAPL and then

separate from what is sorbed to understand the capacity of the fraction; otherwise, 

another approach is to use the total mass

18
Workshop Report Workshop Discussion

— If the fraction capacity is known, how fast the NAPL is flushed would indicate the mass

transfer rate

— The mass transfer rate could then be parameterized for a leaching test

— MCL could be used with known volume of water to back calculate representative

velocity – Representative velocity is the ratio of mass that comes out in a certain volume 

of water to predict retention time

• With regards to NAPL leaching:

— A batch equilibrium test would evaluate mass transfer, and provide an upper limit

(worst case) 

— A column test with pulverized material would estimate flux from stabilized material

• EPA presented preliminary data for organic contaminant groups found at Superfund sites to

introduce the discussion of disposal scenarios and wastes that may require leaching testing

for organics. Based on an analysis of Superfund decision documents (e.g., Records of

Decision, Amended Records of Decision), both volatile and semi-volatile organic

contaminants are common at Superfund sites. For example:

— Halogenated volatile organic compounds (primarily chlorinated VOCs) are

contaminants of concern (COCs) at approximately 70 percent of these sites

— PAHs are COCs at half of the sites, and other semi-volatile organic (e.g.,

pesticides/herbicides, polychlorinated biphenyl (PCBs) are also common

— Based on four recent years (Fiscal Years 2009-2012), 18 decision documents include a

solidification/stabilization remedy for organic contaminants. Of these, about half have 

or may have NAPLs, and about half are using solidification/stabilization as a 

pretreatment prior to offsite disposal

— Common contaminant distinguishing characteristics include:

 Polarity

 Hydrophobicity

 Non-Ionic

 Ionic (not likely a problem but pH can become an issue)

— Priority organics of concern include:

 Organo-metallic compounds

 Combined contaminants

 Mercury

• The 40 constituents regulated in the 1990 Toxicity Characteristic (TC) Rule may be a good

starting point for organic constituents for which to consider testing. Note that the TC Rule

was developed at a time when MSW landfills did not have liners and many industries of

today did not exist; therefore, some of the underlying assumptions are dated.

— Could initially consider the basic parameters that govern the release of the majority of

organic contaminants and situations, recognizing there will be exceptions, and then 

design a flexible system that can accommodate most constituents and matrices

• Some organic contaminants are recalcitrant, transform in the environment, and are toxic at

low levels; the potential occurrence and toxicity of daughter products is also a concern, as

well as preventing them from mobilizing into groundwater.

19
Workshop Report Workshop Discussion

• Participants briefly discussed scenarios where leaching of organics may be of concern:

— Leaching related to industrial waste is the focus EPA’s Resource Conservation and

Recovery Act (RCRA) program 

— Waste pharmaceuticals (expired products) management was mentioned, but workshop

participants noted direct exposure is also a concern in addition to leaching 

— The need to identify specific examples of scenarios that may be most problematic for

leaching was discussed

— From an EU perspective, a lesson learned was to develop methods based on the material

rather than the application to reduce the number of duplicative test methods

• Participants discussed scenarios where leach tests would be needed:

— For Superfund, EPA is managing old contaminated sites

— For RCRA, EPA is dealing with newly generated waste. Focus is primarily on the existing

list of approximately 40 constituents listed in the regulation, but also dealing with 

industries that did not exist at the time of regulation. The primary focus is on industrial 

waste

• Could consider worst case scenarios (e.g., weathering scenario that includes degraded

[crumbled] source material) from a chemical and physical stability perspective when

designing leaching tests to account for a wide range of external conditions to ensure test

results reflect worst case conditions.

• Concrete is another example of a material that often cracks under external conditions and

may be best represented by a monolithic sample in the laboratory, rather than a pulverized

sample. The movement of constituents through concrete depends on the movement of

water by gravity and interconnectedness of cracks.

• Regarding representative site samples, Dr. van der Sloot indicated that research from a

heterogeneous MSW landfill site showed that the composition of the leachate was rather

homogeneous and consistent throughout the face of excavation.

• Testing a composite sample by the full tests in conjunction with single step tests (own pH

batch) on spatially distributed samples can be used to place site-wide variability in

perspective to the more detailed information provided by the full testing of a composite

sample. This approach provides for detailed information at reasonable cost.

• Laboratory quality assurance and quality control procedures, including sample preparation

techniques and separation procedures, are important.

• Conducting training and outreach (e.g., through webinars) for both policymakers, regulators

and laboratories could improve stakeholders’ understanding of the factors that affect

organics leaching and important nuances related to conducting leaching tests.

3.4 Applicability of LEAF Methods

• Participants reiterated that a leaching framework is a scientific evaluative tool that provides

more accurate characterization of leaching that can be considered within a regulatory

decision framework.

20
Workshop Report Workshop Discussion

• It is important to consider the purpose of the leaching test (define how the data will be

used), desired testing output, and define a decision pathway such as an elution curve, L/S

equilibrium, mass transfer, or NAPL concentration.

• The LEAF How-to Guide that is currently being developed for inorganic constituents

describes the suite of tests, the use of simplified screening level testing, as well as more

detailed characterization to compare results to known thresholds. The document offers

guidance on how to select the appropriate test for the material of interest. LEAF methods

can be useful for evaluating multiple inorganic contaminants with unknown release

potential.

• Suggested applications of a leaching test framework at waste cleanup sites included:

— To estimate contribution of a source material to mass flux and transport, given

heterogeneous distribution of contaminants often seen at contaminated sites;

— To support treatability studies and provide insight on the best combination of remedial

technology to use; and 

— To support performance monitoring.

• A leaching test framework could be useful to make a “go” or “no go” decision for whether to

apply stabilization treatment.

— Leaching test methods may be used to estimate release rate at the physical boundary of

the treated/stabilized waste as an indicator of performance

• Participants were reminded that leaching test methods evaluate the leaching potential of

the source material; leach test results are then used in fate and transport modeling to

predict future groundwater concentrations.

• The LEAF testing methods are basic scientific tools that offer results that can then be

evaluated within the context of a specific scenario. The existing LEAF framework

established for inorganic contaminants is flexible enough that the specific context of the

waste material can be considered after generating test results. This logic is in contrast to

TCLP where the context of the waste material is considered prior to testing.

• Participants discussed how to evaluate whether methods adequately predict leaching. Dr.

van der Sloot noted that the EU does not currently have data on organics to compare what

was predicted through testing and modeling to what was observed in the field, but through

the sustainable landfill project such data should be available in 2016.

— It would be best to integrate laboratory testing, modeling, and field results to assess the

accuracy of predictions based on laboratory data (analogous to the approaches taken 

for inorganic contaminants, e.g., Lab-to-Field study). No or very limited data is available 

today. 

21
Workshop Report Workshop Discussion

22
Workshop Report Workshop Agenda

Appendix A

Workshop Agenda

A-1 
Workshop Report Workshop Participants 

A-2 
Workshop Report Workshop Participants 

USEPA Workshop on Considerations for Developing Leaching Test Methods for 

Semi- and Non-Volatile Organic Compounds

Workshop Agenda

Day 1: September 16, 2015 (Wednesday)

Presentation/Discussion Objective(s) Presenter or Moderator

Welcome, Logistics, and Introductions Linda Fiedler, OSRTI

Workshop Objectives Purpose of workshop for ORCR and 

OSRTI

Greg Helms - ORCR

Robin Anderson - OSRTI

Key Parameters or Drivers that Govern the 

Source Term at the Unit Boundary for 

Subsurface Leaching of Semi- (SVOC) and 

Non-Volatile (NVOC) Organic Chemicals

Identify factors that either retard or 

enhance leaching of semi- and nonvolatile organics (e.g., adsorption/ 

desorption/multi-phase partitioning, 

equilibrium vs diffusion controlled 

release).

Charles Werth, 

University of Texas – 

Austin

What is our field test experience related to 

organics leaching?

Estimation of Source Term Concentration for 

Organics Contained on Superfund Sites

What problems are being encountered 

in real-world applications from 

estimation of source term 

concentration at the unit boundary 

using present methods?

Craig Benson, University 

of Virginia

Ed Barth, ORD/NRMRL

European and International Standards on 

Leaching of Organic Contaminants, Available 

Tools and Recent Developments for 

Assessment of Organic Contaminants

Provide understanding of what 

currently is in use and the status of 

standardization and validation.

Hans van der Sloot, 

Consultant (retired from 

the Energy Research 

Center of the 

Netherlands)

What is LEAF for inorganics? What lead to its 

development? What was the process and 

timeline for developing and validating the 

methods?

Provide understanding of work done 

to develop and validate LEAF. 

Greg Helms, ORCR

Susan Thorneloe, 

ORD/NRMRL

What laboratory methods are available to 

measure the factors that impact leaching of 

semi- and non-volatiles?

Identify laboratory methods that 

measure the factors that impact 

organics leaching. 

Greg Helms (Moderator)

Existing Tools and Limitations to Address 

Leaching of Organic Species

Describe capabilities of existing leach 

test methods to measure factors that 

impact organic leaching, and which 

factors existing methods cannot 

address.

David Kosson, 

Vanderbilt University

Day 2: September 17, 2015 (Thursday)

Review of Day 1 Greg Helms, ORCR

What are the capabilities of existing leach 

test methods to measure factors that impact 

leaching of semi- and non-volatiles?

Discuss capabilities of existing leach 

test methods to measure factors that 

impact organic leaching, and which 

factors existing methods cannot 

address.

Greg Helms

(Moderator)

What are the source materials, matrices and 

constituents of potential concern and how 

are these considered in determining the 

reference materials?

Identify reference materials, 

representative matrices, and 

constituents.

Dave Jewett, ORD

(Moderator)

Closing Remarks and Adjournment Linda Fiedler

A-3 
Workshop Report Workshop Participants 

A-4 
Workshop Report Workshop Participants

Appendix B

Workshop Participants

B-1 
Workshop Report Workshop Participants

B-2 
Workshop Report Workshop Participants

USEPA Workshop on Considerations for Developing Leaching Test Methods for 

Semi- and Non-Volatile Organic Compounds

Workshop Participants List

Name Organization 

USEPA

Robin Anderson Office of Superfund Remediation and Technology Innovation (OSRTI)

Linda Fiedler OSRTI

David Bartenfelder OSRTI

Greg Gervais OSRTI

Pamela Barr OSRTI

Jeff Heimerman OSRTI

Kathy Davies Region III

Greg Helms Office of Resource Conservation and Recovery (ORCR)

Schatzi Fitz-James ORCR

Shen-Yi Yang ORCR

Christie Langlois ORCR

Susan Thorneloe Office of Research and Development (ORD)/National Risk Management Research 

Laboratory (NRMRL) (Research Triangle Park)

David Jewett ORD/NRMRL (Ada)

Ed Barth ORD/NRMRL (Cincinnati)

Kelly Smith ORD/NRMRL (Cincinnati)

OTHER PARTICIPANTS

David Kosson Vanderbilt University

Hans van der Sloot Consultant (retired from the Energy Research Center of the Netherlands)

Craig Benson University of Virginia

Charley Werth University of Texas (Austin)

Molly Rodgers Eastern Research Group, Inc. (ERG) (EPA Contractor)

Katie Connolly ERG (EPA Contractor)

B-3 
Workshop Report Workshop Presentations

B-4 
Workshop Report Workshop Presentations

Appendix C

Workshop Presentations

C-1
Workshop Report Workshop Presentations

C-2
Keyparametersordriversthatgovernthesource

termattheunitboundaryforsubsurfaceleaching

ofsemi (SVOC)andnonvolatile(NVOC)organic

chemicals

Charles Werth

Civil, Architectural, and Environmental 

Engineering

UT Austin

VOCs,SVOCsandNVOCsAreinAir,

Water,Solid,&NonAqueous Liquid

Phases

GEOSORBENT 

 WATER OR GAS 

IN MACROPORES 

SOOT 

Micropores 

Mesopores 

Mineral Phase 

Water Film 

Aged or Weathered NAPL 

Clay Particles 

and/or Oxide 

Coatings 

Dense SOM 

Amorphous SOM 

SOM

NAPL 

Encapsulated 

Amorphous SOM 

NAPL 

Luthy etal.,ES&T,1992

SolidPhases

Include:

1) Natural

Components

ofSoilsand

Sediments

2) Sorption

Amendments

toSequester

Pollutants

3) Precipitates

that

Encapsulate

Pollutants

LeachingisControlledBytheCapacity

oftheDifferentPhasesfortheOrganic

ofInterest,andtheMassTransferRate

fromEachPhase

a

Ca

t  N

N

t  b

CSORB

t

 aD2

Ca

x2  q

Ca

x Solute

advection

inleachate

Solute

dispersion

/diffusion

inleachate

Solute

accumul

ationin

solids

Solute

accumul

ationin

NAPL

Solute

accumul

ationin

leachate

ThisCanBeExpressedMathematicallyBytheSimplifiedExpression

BelowForPollutantRemovalMechanismsinLeachate

MassTransfer

BetweenPhases:

MassTransport

inWater:

CanApproximateLeachingFromSorbed

andNAPLPhaseswithaFirstOrder

ExpressiontoIllustrateDependenceon

CapacityofEachPhaseforPollutantand

MassTransferRateConstant

a

Ca

t  N

N

t  b

CSORB

t

 aD2

Ca

x2  q

Ca

x

N

N

t  kLa  	 CSOL Ca

CSORB

t  ks CSORB  KFCa

NF

 	

SoluteinNAPLgovernedbymasstransfertowater:

masstransferrateconstant,kLa

aqueoussolubility,CSOL

bulkaqueousconcentration,Ca

Soluteinsolidgovernedbymasstransfertowater:

masstransferrateconstant,ks

sorbed phaseconcentration,CSORB

bulkaqueousphaseconcentration,Ca

isothermparameters,KF,NF

C-3
AirPhaseHoldsLittleSVOCsorNVOCs

RelativetoSolidandNAPLPhases,and

ContributesLittletoLeaching

• Capacityofairto

holdcontaminantsis

verysmall(<<1%)

– lowfugacitycapacity,

orlowPsat

• Masstransfer

betweenairand

leachatewateris

relativelyfast

– secondstominutes

1 ,00E-13 1,00E-11 1,00E-09 1,00E-07 1,00 E-0 5 1,00E-03 1,00E-01 1,00E+01 1,00 E+03 1,00E+0 5

P° , vapor pressure (kPa)

Saturated and Unsaturate d Hydrocarbons

Misce llane ous Aliphatic Compounds

Substituted Benzene s

Polycyclic Aromatic Hydrocarbons (PAHs)

Phthalates

Halogenated C 1-C4 Compounds

Polychlorinated Biphenyls (PCBs)

Sulfur-Containing 

Compounds

C18H38 C5H12

C9H20 C3H6

C4H10 C2H6

C4Cl CCl2F2

C16H14 C12H22

(modifiedfromSchwarzenbach etal.,1993)

WaterPhaseRepresentsLeachate,and

ServesAsaPollutantSinkForOther

PhasesAsItisReplenished

• Capacityofwater

toholdSVOCsand

NVOCsistypically

small

• Isaffectedby

presenceofsalts,

cosolvents,

dissolvedorganic

matter(DOM),&

colloids

1.0 0 E- 0 8 1. 0 0 E- 0 6 1.0 0 E- 0 4 1. 0 0 E- 0 2 1. 0 0 E+0 0 1.0 0 E+0 2 1. 0 0 E+0 4 1. 0 0 E+0 6 1. 0 0 E+0 8

Cw

sat water solubility (mg/L)

Saturated and Unsaturated Hydrocarbons

Miscellaneous Aliphatic Compounds

Substituted Benzenes

Polycyclic Aromatic Hydrocarbons (PAHs)

Phthalates

Halogenated C1-C4 Compounds

Polychlorinated Biphenyls (PCBs)

Sulfur-Containing Compounds

C18H38 C5H12

C9H20

O

C3H6O

C4H10 C2H6S

C4Cl6 CCl2F2

C12H14 C16H22

(modifiedfromSchwarzenbach etal.,1993)

IncreasingIonicStrengthDecreases

theAqueousSolubility

KS="saltingout"constant, (~0.150.3;e.g.Benz=0.19,Naph =0.22inNaCl solutions)

Cwsal sat =saturationconcentrationinwaterwithsalt[mol L1;gL1]

Cw

sat =saturationconcentrationindistilledwater[[mol L1;gL1]

Csal =saltconcentration[mol L1]




 


  L

mol

sal C

S K sat

sal,wC

sat Cw log

 3.2 	 sal CS Kexp sat Cw sat C sal,w   1 2 34

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0

[salt]tot (mol/L)

Log(Cwsat/Cw,saltsat)

(Schwarzenbachetal.,1993)

Pure

SVOC

Water

and

salt

log

C ,

C

f w Co

sat

w

sat   Co

Cw,Cosat =saturationconcentrationinpresenceofcosolvent[mol/L;g/L]

fCo=fractionofcosolvent[]

 =solubilizationconstant[]or"cosolvencypower"

 increases withdecreasingwatersolubilityofthecosolvent (increasing

hydrophobicityKow.)

Pure SVOC, NVOC

Water and cosolvent 

e. g. methanol

IncreasingCoSolventConcentration

IncreasestheAqueousSolubility

Cw,Cosat = Cw

sat exp ( fCo)

C-4
C

C

f K w DOC

sat

w

sat DOC DOC ,  1

Cw,DOCsat =saturationconcentrationinpresenceofDOC[molL1;gL1]

fDOC =fractionofdissolvedorganiccarbon[kgL1](e.g.:Humic,fulvicacids,surfactants)

KDOC =partitioningcoefficientorganiccarbon/water(Lkg1).

KDOC increaseswithdecreasingwatersolubility(increasingKow )ofthesoluteandincreasing

hydrophobicityormolecularweighttheDOC(KDOC  Kow )

Pure SVOC, NVOC

Water with DOC

IncreasingDissolvedOrganicMatter

ConcentrationIncreasestheApparent

AqueousSolubility

Cw,DOCsat = Cw

sat + Cwsat fDOCKDOC

• Leachingcapacityofsoilsandsediments

dependsonsoil/sedimentpropertiesand

chemicalproperties

• Leachingratedepends

onconcentrationgradient

betweensorbed phase

andwater,andmass transfer

rateconstant CSORB

t  ks CSORB  KFCa

NF

 	

Soils,Sediments,andGeosorbent

AmendmentsCanSorbLargeAmounts

ofVOCs,SVOCsandNVOCs,andSlowly

ReleaseThem

EquilibriumCapacityofTheseSolidsis

DeterminedbyComposition

• Therearebothabsorption(orpartitioning)

andadsorptionenvironments

– Partitioningenvironments

• Relativelyunweathered and/orrecentsoilorganic

matter

• Capacitytoholdcontaminantscanbelarge,and

dependsonamountofthisorganicmatter

• Masstransferfromthissoilorganicmatterisrelatively

fast(hourstodays)comparedtosoiladsorption

environments

– Canassumeequilibriumpartitioningatlowwaterflowrates

– Athigherwaterflowratescanapproximateasfirstorder

CapacityofSoilPartitioningEnvironment

forContaminantsCanbeEstimated

• Relationshipbetweenconcentrationsinwater

andrecentsoilorganicmatterisoften~linear

– Kd =Csorbed /Cwater

• Kd canbedirectlyrelatedtoamountof

organicmatterandhydrophobicityof

chemical

– Kd =Koc *foc

– Where

• Koc ~Kow

C-5
ManyRelationshipsKoc andKow Have

BeenProposedandThereisLotsof

SupportingData

• Therelationshipby

Karickhoff etal.(1979)is

perhapsthemostcommon

– Log(Koc)=1.00*log(Kow)– 0.21

AdsorptionEnvironmentsAreMore

ChallengingtoCharacterize

• AdsorptionEnvironments

– Thermallyalteredand/orcondensedorganicmatterand

blackcarbon

• E.g.,Soot,charcoal,kerogen

– MineralSurfaces,e.g.,Clays

– CompositeAmendments

• Organoclays,activatedcarbonembeddedincements

• Capacitytoholdcontaminantscanbeverylarge,and

dependsonmanyfactors,e.g.,microporosity,surface

area,andsurfacecharge

• Masstransferfromadsorptionenvironmentscanbe

veryslow

– Leachingformonthstoyearstodecades

Natural

Materials

Become

Thermally

AlteredOver

GeologicTime

WithBurial

Living

Organisms Lignin CarboHydrates Proteins Lipids

Recent

Sediment

Principal zone

of oil formation

Zone of gas

formation 

Humic Acids

Fulvic Acids

Humin

Biological

Markers

Kerogen

Carbon

Residue

Methane +

Light Hydrocarbons Gas

Crude

Oil

Hydrocarbons

Low to

medium MW

high

MW

Cracking Cracking

Thermal

degradation

Release of

trapped molecules

Retention of

carbon skeleton

Microbial degradation

Polymerization

Condensation

Diagenesis Catagenesis Metagenesis

SomeThermallyAlteredSorbentsAre

AnthropogenicinOrigin

• Soot

– Combustionproductofhydrocarbons

• Char

– Solidphaseresidualfrombiomassburning

• ActivatedCarbon

– Solidphaseresidualfrombiomassburning,

followedbyactivationbyexposuretoacid,

oxidizing,orreducingconditionsatelevated

temperature

C-6
TheExtentofAdsorptionVarieswith

Sorbate andSorbent

18

TheExtentofSorptionHasBeen

RelatedtoSurfaceArea,Pore

Volume,andMicroporosity

1

10

100

1000

1 10 100 1000

Intraparticel-Porosity N2-BET [cm3

/kg]

CS,max [cm3/kg]

o-Kresol

Benz

TCE

1,2 DCB

1,4 DCB

PHE

subbit. coal

lignite

high vol. bit. coal

charcoal

lignite coke

zeolite Y-200

act. carbon

PolyguardR

 coke

carbon black

HOCsfromwaterat20°C,N2 fromgasphaseat–196°C

CapacityofAdsorptionEnvironmentsfor

ContaminantsMustBeMeasured

• Relationshipbetweenwaterandsoil

concentrationsistypicallynonlinear

– TheFreundlich equationisoftenusedtomodel

data

• Csorbed =KF CwaternF

– TheLangmuirisotherm

equationisalsoused used

• Csorb/Csorb,max =KadsCwater /(1+Kads Cwater)

BothPartitioningandAdsorption

EnvironmentsareOftenPresentinSolids

• Twopart

modelsusedto

capture

sorptionto

both

environments

simultaneously

– qT=qab+qad

AllenKingetal.,AWR,2002

C-7
TheContributionofPartitioningand

AdsorptionEnvironmentsVariesWidely

DependingontheSorbent

• (left)Pyrene sorptiontothesilty/clayeyaquitard

materialand(right)1,4dichlorobenzene

sorptiontosubbituminouscoal

AllenKingetal.,AWR,2002

MassTransferfromAdsorption

EnvironmentsisThoughttoBeDiffusion

Controlled

• Contaminantsdiffusethrough:

– tortuousmatricesofinflexibleorganicmatter

– poresinmineralsandbetweencementedmineral

fragments

• Insomecasesaretardeddiffusionconcept

hasbeeninvoked

– E.g.,Diffusionthroughinternalporesofparticle

thatisretardedbysorptiontoporewalls

– Notapracticalmodelingapproach

SlowMassTransferisOften

ApproximatedwithaFirstOrderMass

TransferExpression

• Recallthesingle10 masstransferexpression

• Insomecasestwoormorefirstorder

expressionsareusedinparalleltodescribemass

transferfrommultipleadsorptionenvironments

CSORB

t  ks CSORB  KFCa

NF

 	

CSORB,Part

t  ks,Part 	 CSORB,Part  KdCa

CSORB,Adsorb

t  ks,Adsorb CSORB,Adsorb  KFCa

NF

 	

PoorlySorbing SolidPhasesAreAlso

PresentinSamplesAnalyzedforLeaching

• Cementsusedtoencapsulatesolidwaste

materialslikecontaminatedsoils

• Oxidizedpotassiumpermanganatethat

precipitatesaroundsoilandNAPLphasesand

createsadiffusionbarrier

• Compositesofthesematerialsthatalso

containadsorbents

– E.g.,activatedcarbonembeddedincements

C-8
PrecipitatesCreateSerialBarriersto

Leaching

• Reducespermeabilitysoincreasesdiffusion

lengthscaleinstagnantwater

• Createasolidbarrierthatonlyallows

contaminantreleasethroughhindered

diffusion

– Ifprecipitatescontainadsorbents,thenhave

retardeddiffusion

ContributionofContaminantsOriginally

inTrappedNAPLtoLeachateCanBeLarge

• CanbeapureNAPL,oraNAPLmixture

• Masstransferistypicallydescribedbyfirstorder

process

• MasstransferfromNAPLisrelativelyfastcomparedto

adsorptionenvironments

– Canbelimitingifdiffusionlengthscalesthroughlow

permeabilityzonesarelargeandathighwatervelocities

N

N

t  kLa  	 CSOL Ca

N

N,i

t  kLa,i x 	 i

CSOL,i Ca,i

PureNAPL

NAPLmixture,xi

=molefraction

RecalltheDifferentPhasesThat

ContributetoLeaching

GEOSORBENT 

 WATER OR GAS 

IN MACROPORES 

SOOT 

Micropores 

Mesopores 

Mineral Phase 

Water Film 

Aged or Weathered NAPL 

Clay Particles 

and/or Oxide 

Coatings 

Dense SOM 

Amorphous SOM 

SOM

NAPL 

Encapsulated 

Amorphous SOM 

NAPL 

MassTransferProcessesCan

BeinParallelorinSeries

SOM

NAPL 

B

A

D

F

E

A B WaterPhase(Series)

C D WaterPhase(Series)

E F WaterPhase(Series)

WaterPhase

C

Water

Phase

Water

Phase

Water

Phase

(Parallel)

(Parallel)

C-9
ManyModelsHaveBeenDevelopedto

DescribeTheseMassTransferProcesses

• Recallthesimpleleachingmodelwithmass

transferinparallelthatIshowedearlier

a

Ca

t  N

N

t  b

CSORB

t

 aD2

Ca

x2  q

Ca

x

N

N

t  kLa  	 CSOL Ca

CSORB

t  ks CSORB  KFCa

NF

 	

InParallel

TheCapacityandMassTransferRate

ConstantsforEachPhaseDeterminethe

RelativeContributionstoLeaching

Phase Capacity MassTransferRate

Air Low Fast

Water Low NA

Soil(Partitioning) High Medium/Fast

Soil (Adsorption) VeryHigh VerySlow

BlackCarbon VeryHigh VerySlow

Composites Medium/High Slow/Medium

Cement Low Slow/Medium

OrganoClays High Slow/Medium

NAPL High Medium/Fast

TheContactTimeofWater,orWaterFlow

Rate,DeterminesHowFarMassTransfer

ProcessesAreFromEquilibrium

• Canusedimensionalnumberstoevaluate

• FirstDamkohler Number,Da1

– Da1 =Lks /v

• L=lengthofleachatesamplealongflowdirection(L)

• ks =masstransferrateconstant(t1)

• v=averagelinearvelocity(Lt1)

– LargeDa1,closetoequilibrium

– SmallDa1,masstransferimportant

C-10
IssueswithOrganicTransportin

PhysicalModelsofBarrierSystems

CraigH.Benson,PhD,PE,NAE

SchoolofEngineeringandAppliedScience

UniversityofVirginia

chbenson@virginia.edu

ModernWasteContainmentSystems

1.

2. 3.

Highlyengineeredsystemsthatareprotectiveoftheenvironment

Single Composite Liner Systems

• Syntheticgeomembrane

andnaturalclaybased

layerworksynergistically

andhaveverylow

leakagerates.

• Exceptionallystrongtrack

recordforwiderangeof

wastestreamsworld

wide.

• Verylonglifetimes

expected,1000+yr

C-11
Double Composite Liner Systems

• Doublesystems

withleakdetection

essentially

eliminatesrelease

ofconstituents.

• Foundtobe

extremelyeffective

worldwide,but

conservatismmay

notbenecessary.

LinerLeakage

0

200

400

600

800

1000

10-9 10-8 10-7 10-6 10-5

Leakage Rate (l/ha-d)

Hydraulic Conductivity of the Clay Liner (cm/s)

Clay

Composite

12 holes/ha

Composite

2 holes/ha

EPAFieldDatabase

GMClay

GMGCL

Geomembrane

Organic

Diffusion

Inorganic or Organic

Advection

Subgrade or

Clay Liner

Organic

Diffusion

Hole

C/Cl

1.0

C/Cl = Kg

Ce/Cl

CeKg/Cl

t

g

Subgrade or

clay liner

Geomembrane

AdvectiveDiffusiveTransport

throughHoles

DiffusiveTransportthrough

IntactGeomembrane

Requires3Dnumericaltransport

analysis

Requires1Dnumericaltransport

analysis

VOCsinLysimetersBeneathLinersinWisconsin

0.1

1

10

100

1000

1234567

(data from Benson and Edil 2005)

Concentration (g/L)

Time (yrs)

PAL

MCL

MCL=MaximumContaminantLevel

PAL=ProtectiveActionLimit

Dichloromethane

C-12
Leachate&LysimeterConcentrations

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10

Leachate

Lysimeter

Leachate

Lysimeter

Leachate

Lysimeter

Leachate

Lysimeter

Leachate

Lysimeter

Ln(concentration(g/l))

1,1-DCA Benzene Ethylbenzene Tetrahydrofuran Toluene

CompositeLinerVOCTransportExperiments

• Reservoirspiked

withsodiumazide

toeliminate

microbialactivity

leadingtolosses

• Samplingvolume

selectedtohave

negligibleimpacton

transport

0

10

20

30

40

50

0 50 100 150 200 250 300 350 400

Replicate 1 (depth = 60 mm)

Replicate 2 (depth = 60 mm)

Replicate 3 (depth = 60 mm)

Foose et al. (2002) (depth = 60 mm)

POLLUTE (depth = 60 mm)

Replicate 2 (depth = 90 mm)

Foose et al. (2002) (depth = 90 mm)

POLLUTE (depth = 90 mm)

Time (days)

Concentration (mg/L)

(e) Chlorobenzene

Depth = 60 mm

Depth = 90 mm

VOCConcentrationsinClayLiner

withModelPredictions

DualCompartmentTestsforDiffusion(Dg)&

Partition(Kg)CoefficientsforGeomembrane

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100 120

Upper Reservoir

Model DC-KD (UR)

Model DC-D (UR)

Lower Reservoir

Model DC-KD (LR)

Model DC-D (LR)

Relative Concentration (C/Co

)

Time (days)

(b)

C-13
0.0

0.2

0.4

0.6

0.8

1.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Measured data

Model KB-KD

Model KB-D

Relative Concentration (C/Co

)

Time (day)

KineticBatchTestsforDiffusion(Dg)&

Partition(Kg)CoefficientsforGeomembrane

• Modelfits

providesDg &Kg.

• Acceptableif

geomembraneis

homogeneous

material.

0

20

40

60

80

100

120

140

0 20 40 60 80 100 120 140

 

 

KgDC-KD

KgDC,corrected

Kg,EB

K

g,DC

TCE

TOL

CB

MTBE

MC (a)

• Biasfromdouble

compartment

duetolossin

flange.

• Eliminatingloss

resultsingood

agreement.

Partition(Kg)CoefficientsforGeomembrane:

DoubleCompartmentvs.KineticBatch

• Ethylvinylalcohol(EVOH)core

• PEjacket(LLDPEorHDPE)

• TiesheettobindEVOHandHDPE

1.0mmEVOH

geomembrane EVOHfilm

1.0mmLLDPE

15mmEVOH

geomembrane EVOHfilm

1.0mm

HDPE

CoExtrudedEVOHGeomembrane ColumnsforEVOHCompositeLinerTests

Compactedclay

liner

Upper

reservoir

Sampling

port

Stir

bar

Stir

Stainlesssteel

beads

Geomembrane

Effluentbag

70mm 120mm

40mm

20mm

20mm

Glassfiberfilter

Samplingport

PTFEgasket

GCL

12mm

70mm 70mm

C-14
NewFlangeDesign

WellMixedUpperBoundary

ColumnTestsforEVOHCompositeLinerExperiments

PTFEbagincludingDDIwaterto

applyhydraulicgradienttoliner

TCEConcentrationsinClay

ComponentofEVOHCompositeLiner

0

2

4

6

8

10

12

0 50 100 150 200 250 300 350 400

Concentration (mg/L)

Time (d)

20 mm-sampling depth

40 mm-sampling depth

80 mm-sampling depth 

C0 = 100 mg/L

CCL = 0.12 m

Sampling points (Not to scale) 

• Repeatable.

• Goodagreement

withtheory(not

shown).

C-15
ReactiveBarrierStrategyforCreosote

Forcreosote

containment:

 Impermeableto

DNAPL

 Permeableto

groundwater

 RemovePAHs

dissolvedinground

waterflowingthru

barrier.

Create a Variably Permeable Reactive Barrier – VPRB

WhatareOrganoclays?

 Nabentonite(high

montmorillonitecontent)

exchangedwithquaternary

ammoniumcations

 Cationcharacteristicbinds

moleculetoclaysurface.

Organiccomponentprovides

sorptionsiteforPAHs

 Benzyltriethylammoniumor

hexadecyltrimethyl

ammonium

ET1Organoclay

CreosoteRemediation– Michigan’sUpperPeninsula

UPisamajorsource

ofironore.

Loadironoreonto

shipsfortransferto

Chicagorail

terminals.

Creosoteusedfor

railroadtietreating

forironorelines.

SiteAerialView– IronOreLoadingFacility

UpperPeninsula,Michigan

Existing AB

Railroadtie

treatingfacility

whereties

soakedin

creosote(wood

preservative).

Creosote

residuefrom

pitsmigrated

thrusubsurface

&ultimatelyto

lake.

C-16
Existing AB

Hypothetical AB

FullScaleBarrier

 Coverbroadareato

ensureallstringers

arecaptured.

 Keyintounderlying

clayaquitard.

 Polisheffluentinto

LakeMichiganusing

subaqueouscap

(organoclaycoremat)

Proposed Barrier

Location

CrossSectionParalleltoFlow

Source Lake

Michigan

Creosotedischargingintolakecreating“hotspots”

GroundwaterwithdissolvedPAHemanatingintoLakeMichigan

Trial

barrier

CrossSectionPerpendiculartoFlow

(lookingupstream)

EC-199

C-17
HydraulicConductivityRecord

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

0 20 40 60 80

NAPL Conductivity (cm/s)

Elapsed Time (d)

NAPL Water

Material Hydraulic

Conductivity(cm/s)

PM199 7.6X1010 (forDNAPL)

9.6X1010 (forwater)

ET1 3.4X109

EC199 3.7X1010 (forDNAPL)

1.1X109 (forwater)

0%PM199 4.1X105

10%PM199 2.6X106

25%PM199 8.6X109

50%PM199 2.8X109

 Nearlyimpermeableto

DNAPL,butvariesbyclay.

 CanobtainsimilarlowK

withasandblend.

PM199 ET1

AqueousPhaseColumnExperiments

Columns Influent Effluent

Pump Objective:

 Evaluateorganoclay

underflowthrough

conditions

 Determineif

parametersfrom

batchtestsprovide

reasonable

predictionsof

sorptionunderflow

throughconditions.

Thickness

of Barrier 

(m)

Material PVF to MCL in 

Column Test

Longevity (yr) 

at 1 m/yr

0.5 m

PM-199 1843 307

ET-1 148 24

EC-199 920 154

25% PM-199 461 77

50% PM-199 922 154

1.0 m

PM-199 1843 614

ET-1 148 49

EC-199 920 307

25% PM-199 461 154

50% PM-199 922 307

BreakthroughfromBatchAdsorptionData

(timetobreakthroughatMCL)

C-18
0

5

10

15

20

25

0 40 80 120 160 200 240 280 320

(a)

Glass Beads

PM 199

ET-1

EC-199

Field Highest Conc.

Concentration (g/L)

PVF

0.0

2.0

4.0

6.0

8.0

10.0

0 40 80 120 160 200 240 280 320

(b)

Concentration (g/L)

PVF

EffluentfromOrganoclayColumns

 Breakthroughofnaphthalene(aboveDL)inET1

organoclay(lowestOCfraction)~190PVF

 Nootherbreakthroughin10months.

Naphthalene

(logKow=3.30)

Acenaphthene

(logKow=3.92)

• Experimentalapparatuscanhaveasignificant

effectonoutcomeoftransportexperimentswith

hydrophobicorganiccontaminantsatlow

concentrations.

• Evaluatematerialsbeforehandassinksfor

organiccontaminants,eveninthemostobscure

components.Avoidfalsenegative.

• Evaluateapparatusforunintendedsinksfor

organiccontaminants.

• Developexpectationsforoutcomesof

experimentstoproviderealitycheckondata.

SummaryRemarks

Acknowledgements

• USDepartmentofEnergy,Environmental

Management,ConsortiumforRiskEvaluation

withStakeholderParticipation(CRESP)

• USNationalScienceFoundation

• WisconsinDepartmentofNaturalResources

• KurarayAmericaInc.

• CETCO

• UnionPacificRailroadCorporation

C-19
EstimationofSource

TermConcentrationfor

OrganicsContainedon

SuperfundSites

EdBarth,PhD,PE,CIH,RS,BCEE

NationalRiskManagementResearch

Laboratory(NRMRL)

OfficeofResearchandDevelopment

Cincinnati,OH

PurposeofPresentation

• BrieflydescribeandpresentexamplestoillustratehowEPARegional

Offices(SuperfundProgram)andEPAOfficeofResearchand

Development(ORD)havehistoricallyandcurrentlyevaluated“the

sourcetermattheunitboundary”forremediesinvolvingonsite

containmentoforganicmaterials(includingDNAPLs)

VariousTypesofDNAPLSites

• Petroleum

• WoodPreserving(Creosote,PCP)

• MGP

• OrganicCompoundFormulationIndustries

• WasteRecyclingIndustries

RemediationoptionsforDNAPLcontaminated

soil	


• Containment(cap,slurrywall)

• ProductExtractionandRecovery

• Insitusolidification/stabilization(ISS)

• ISSwadditives(carbonororganoclays)

• Completeorpartialdegradationviainsituheating,insitu

combustion,insituchemicaltreatment(oxidation,dechlorination),

orinsitubioremediation

C-20
PreplacementEvaluationMethods

• OilyExtractionProcedure

• PaintFilterTest

• EPToxicity

• MEP

• TCLP

• SPLP

• ANSI16.1with/withoutsitegroundwater

• Columnleachtestingmethods(SWLP,sedimentcores)

• ORDCenterHillLab.studiesinvolvingShrinkingCoreModel,ConstantpHleach

• note:VariousConferencesandSymposiums(suchasHMCRI,ASTM)havesuggestedothermethodswhichhavenottransferredtotheSuperfundProgram

PostplacementEvaluationMethods

• Coring:leachingandmicroscopy(LSU,EPASITEprogram)

• Waterqualitymonitoringofterapods placedinsurfacewater(SUNY)

• SPMEanalysisofsedimentporewater

• Groundwatermonitoring(SuperfundFiveyearreviewrequirement)

OtherOrganizationswithISSGuidance

ITRCGuidance:Perf.Specs.2011

• Strongemphasesonphysical

propertiessuchas:

• UCS

• hydraulicconductivity

• EPATCLPandLEAFMethods

EnvironmentalCanada.1988

• Freeze/thawcycling

• Wet/drycycling

• Microscopy

• Variousleachmethods

AlternativeEvaluationMethods:BondingStrength

IndicatorTechniques(Soundararajan,Barth,

Gibbons.1990)

• OrganicSolventExtraction(methylenechlorideorhexane)

• FTIR

• DSC

• XRD

note:thisqualitativepredictionapproachwasconsistentwith

polymericencapsulationprocessesquantitativepredictionapproaches

usingArrheniusmodelingofafailedphysicalparameterduring

acceleratedweatheringtests

C-21
FurtherBondingStrengthIndicatorTechniques

(Johnston,Barth,Chattopadhyay.2012)

• Containment/ChallengeofcontainingaDNAPLsoup(Mukherji,etal.

1997)

• Sequentialextractiontest(similartoTessier seriesexceptlaststage)

• Considerationoffacilitatedtransport(vialowvs.highcolloid

competion environment)

• note:Inaseparatestudy,porewaterextractionviacentrifuge

(sediments)appearstobeanotherpredictivetool

Structural,Spectroscopic,andSorptionStudiesof

AlkylammoniumModifiedClayMinerals

Characterization

• StructuralMethods

• PowderXraydiffraction:

• Targetdspacingof~3.8nmcorrespondingto

intercalationfo2layersofDMDODAinclayinterlayer

• Thermalanalysis:

• TGAtoconfirmsurfaceloadingofDMDODAinclay

interlayer.Targetsurfaceloading:44%OM;35%OC

• Assessthermalstabilityofclayandinfluenceof

organiccationondehydroxylation

• Spectroscopic

• FTIRSpectroscopy

• Gainmolecularinsightabouttheinteractionofthe

organiccationwiththeclaymineral.

• Molecularprobeofalkylchainordering.Measureof

organophilicityoforganoclay

3627

2918

2849

1469

1043

919

801

722

625

0

.5

1

1.5

2

2.5

3

3.5

 4000 3500 3000 2500 2000 1500 1000 

3% mix of organo-clay Batch 1 in KBr

1/(0.55)*9pr66l

9pr66l, 18.3971 mg

1/(0.57)*9pr66k

9pr66k, 18.1338 mg

1/(0.57)*9pr66j

9pr66j, 17.8947 mg

mg

10

11

12

13

14

15

16

17

18

19

min

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 °C

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46

\1/(0.57)*9pr66j

9pr66j, 17.8947 mg

\1/(0.57)*9pr66k

9pr66k, 18.1338 mg

\1/(0.55)*9pr66l

9pr66l, 18.3971 mg

^-1

1

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 min

STARe Johnston Lab: METTLER SW 9.01

0

500000

1000000

Counts

Position [°2Theta] (Cobalt (Co))

2.50 3 3.50

 9pr66n

 9pr66o

 9pr66m

LessonsLearned:“Normalize”forMassBalance

ConcerningPAHsanalyticaltechniques?

• ReductionofPAHsinlabsamplesduetophotochemicaloxidation

exposure(KochaneyandMaguire.1994)

• Headspacevolatilization

• Dilution

• Sorptionontoglassware

• Oilsheensonsamplesurface

SomeCurrentApproachesUsedbyUSEPA

Regions(proposedbyEPAcontractors)

• LEAFmethods

• Sitegroundwater

• CoatedGlassware

• Partitioning/NAPLsaturation

• Porewatermodelsbaseduponpartitioning

C-22
CaseStudy:AtlanticWoodIndustry,VA:UseofOC

forinsituapplicationatAtlanticWoodSite AtlanticWoodIndustrySite

• Region3contactedORDbecauseTCLPcriteriaforPCP(0.001mg/l)

couldnotbemetwithcementbasedprocess

• BaseduponpreviousORDworkwithDr.StephenBoydofMSU,ORD

suggestedtheuseofOC

• Additionoforganoclay greatlyreducedtheTCLPvalueofPCP,butnot

belowcriteriaestablishedforthesite

CaseStudy:GowanusCanal,NY:ISSofNAPL

ContaminatedSediments

GowanusCanalTreatabilityStudy(Niemet,et

al.2015andGentryetal.,2015)

• SPLP

• EPAMethod1315M:modifiedfororganics:methanolextraction,

PDMSlinedleachingvessel

• DeanStarkfluidporesaturationtoindicateNAPLmobility

C-23
SummaryPoints

SomeEPARegionalOfficeshaveusedleachingmethods,beyondthe

TCLP,toascertainwhetheratreatment/containmentprocessis

adequate

Anarrayofchallengefluidsareavailabletocovertherangeof

extractionrecovery

Whilebondingstrengthindicatormethodsareavailable,theyarerarely

usedintreatmentevaluations

C-24
Hans van der Sloot1, David Kosson2, and Andre van Zomeren3

1 Hans van der Sloot Consultancy, Langedijk, The Netherlands 2 Vanderbilt University, Nashville, TN 3 Energy Research Centre of the Netherlands, Petten, The Netherlands

European and international standards on leaching of 

organic contaminants, available tools and recent 

developments for assessment of organic 

contaminants

USEPA Workshop on the Measurement of Leaching of Semi- and Non-Volatile Organic 

Compounds September 16, 2015, Washington

Outline

Uses of leaching tests for organics in European context 

(e.g., products, construction materials, remediation, waste 

management, beneficial use) 

Where are organics considered? Which types of organics?

Standardised test methods (including current status of each 

with respect to standardization and adoption)

Available leaching data for organic contaminants

Sustainable landfill scenario (inorganic and organic 

substances)

Standards for organics

European standardised leaching methods for organic contaminants from 

waste, soil and construction products (CEN/TC292, CEN/TC345, CEN/TC351)

International standard methods for organic contaminants from soil 

(ISO/TC190)

Validated National standards: NEN – Netherlands, DIN - Germany 

Non-standardised methods: Netherlands – sediments; Denmark – waste

Recent developments: Ecotox testing for construction products (emphasis on 

biocides) 

Summary of noted differences between inorganic and organic contaminant 

leaching 

Limitations

CEN/TC345Soil

ISO/TC190Soil CEN/TC292Waste CEN/TC292WG8 CEN/TC351+60ProductTC's

Test

Soil,sediments,

compostand

sludge Waste Miningwaste Constructionproducts

pHdependencetest ISO/TS212684 PrEN14429 PrEN14429 PrEN14429#

PrEN14497 PrEN14497

EPA1313* EPA1313 EPA1313 EPA1313

Percolationtest ISO/TS212683 PrEN14405 PrEN14405 FprCENTS166373

NEN7373 NEN7373

EPA1314* EPA1314 EPA1314 EPA1314

NEN7374(2004) NEN7374(2004) NEN7374(2004)

DIN19528 DIN19528 DIN19528

Monolithtest PrEN15863 FprCENTS166372

NEN7375 NEN7375

EPA1315* EPA1315 EPA1315 EPA1315

NVN7376(2004) NVN7376(2004)

Compactedgranulartest NEN7347 FprCENTS166372

EPA1315 EPA1315 EPA1315 EPA1315

Redoxcapacity CEN/TS16660

Acidrockdrainage EN15875

Reactivesurfaces

ISO/CD12782

parts15

Vienna

Agreement

*EPAmethodsincludedinSW846&basedonNEN7348#NotyetadoptedinCEN/TC351(veryrelevantforCPR)

Matrix

Leaching standards by matrix, test type, inorganic (all) and 

organic substances (yellow) 

C-25
Standardized leaching tests for organics – column test*

* Observations from EU standardisation activities

Test name FprCENTS16637-3 ISO/TS21268-3 NEN7374 DIN19528

Type of test Up-flow column leaching test Up-flow column leaching test Up-flow column leaching test Up-flow column leaching test

Origin: CEN TC 351 WG1 ISO TC 190 SC7 WG6 Dutch national standard NEN German national standard DIN 

Field of 

application 

Construction products Soil and soil like materials (e.g. 

sediments) 

Waste, soil and construction 

products 

Waste and construction products 

Particle size 

Max. 22.4 mm (70 -100 mm column 

diameter) or 16 mm (50 – 100 mm 

diameter column) At least 45 % - 55 % 

< 4 mm 

95 % < 4 mm 95% < 4 mm Up to 32 mm. 

Hydraulic 

conductivity of 

the column 

Note: saturated hydraulic conductivity 

usually than 10-8 m.s-1 

saturated hydraulic conductivity higher 

than 10-8 m.s-1 

Not specified. If test takes too 

long, material is mixed with glass 

beads or quartz sand to facilitate 

percolation 

Not specified. In case of poor 

percolation, test carried out after mixing 

the solid with a ratio of 80 % quartz 

sand

Substances Inorganic and non-volatile organic 

contaminants 

Inorganic and non-volatile organic 

contaminants 

PAH, PCB, OCP, EOX, phenols 

and cresols 

Inorganic and non-volatile organic 

contaminants 

Leachant: DMW DMW + 0.001 M CaCl2 DMW 

Diameter and 

height of 

material 

Ø 5 - 10 cm and height 30 cm glass Ø 5 or 10 cm and height 30 cm in 

glass column (top section of PCTFE) 

Ø 5 cm and height 30 cm made 

of glass (repeat if more eluate is 

needed) 

Ø 5 - 10 cm and height 30 cm in glass 

column (wrapped in Al foil to avoid 

biological growth, degradation) 

Amount of solid 0.6—2.4 liter 0.5-2.4 liter 0.4 kg d.w. min. (bed vol = 0.5 L) 0.6—2.4 liter 

Solids packing Light tamping in ca. 5 cm layers (each 

layer made of 3 leveled sub layers) 

Light tamping in ca. 5 cm layers Light tamping in ca. 5 cm layers Light tamping in ca. 5 cm layers 

Top and bottom 

layer 

layer of quartz sand (2 cm) at outlet 

glass wool 

Distribution non-reactive glass fibre 

filterplate (no organic glue) or and 

layer of quartz sand

Glass fibre filter or nylon filter layer of quartz sand (2 cm) at outlet 

glass wool 

Pre-equilibration 12 – 72 hours 48 hours 18 – 72 hours 2 hours 

L/S (l/kg) per 

step: 

cum.L/S: 0.1, 0.2, 0.5,1,2,5,10 cum.L/S: 0.1, 0.2, 0.5,1,2,5,10 cum L/S 0.1, 0.5,1,2,5,10 cum L/S 0.3, 0.7, 1,2 with option to

expand 

Maximum 

accumulated 

L/S: 

10 10 10 2 (optional 10)

Standardized leaching tests for organics – column test*

* Observations from EU standardisation activities

Test name FprCENTS16637-3 ISO/TS21268-3 NEN7374 DIN19528

Tubing Adapted to the substances to be 

analyzed (ISO5667-3) 

ETFE or stainless steel (if only 

organics) 

ETFE, as short as practical Stainless steel tubing 

Number of steps 7 7 6 4 (optional 6 or more) 

Total test time 2 days for L/S=2 and 9 days for 

L/S=10 

3 weeks Dependent on dry mass in 

column (~3 weeks) 

1 day for L/S=2 and 4 days for L/S=10 

Temperature 20 ± 5 20 ± 5 20 ± 2 °C 20 ± 2 °C 

Flow rate (mL/hr) 24.5 ml/hr 12 ml/hour (5 cm column diameter); 48 

cm/hour (10 cm column diameter) 

10 ml/hour 54 ml/hour 

Residence time 5 hours

Collection 

vessels and 

preservation 

Glass with ETFE or PTFE inlay. 

Preservation according to ISO-5667-3 

Glass bottles with PTFE cap inlay. 

Preservation according to ISO-5667-3 

Glass bottles with PTFE cap inlay 

cooled to 0 – 5 °C . 

Glass bottles with PTFE cap inlay. 

Preservation according to ISO-5667-3 

Liquid/solid 

separation: 

(inorganic vs. 

Organic) 

Centrifugation at 20,000 to 30,000 g, if 

needed based on turbidity exceeding 

100 FNU. Optional : 2000 – 3000 g 

with cooling 

Centrifugation at 20,000 to 30,000 g 

Optional : 2000 – 3000 g with cooling. 

Optional filtration for only inorganics 

Filtration through 0.45 m 

membrane filter (KEL-F, Rehova, 

S&S RC55) 

Centrifugation at 20,000 to 30,000 g, if 

needed based on turbidity exceeding 

100 FNU. Optional : 2000 – 3000 g 

with cooling 

Data 

presentation 

Conc. mg/l vs L/S 

Cumulative mg/kg vs L/S 

Conc. mg/l vs L/S 

Cumulative mg/kg vs L/S 

Conc. mg/l vs L/S 

Cumulative mg/kg vs L/S 

Conc. mg/l vs L/S 

Cumulative mg/kg vs L/S 

Additional 

parameters 

pH, EC and optional DOC, turbidity 

and redox potential 

pH, EC, DOC, optional turbidity and 

redox potential 

pH, EC Optional: pH, EC, DOC, turbidity and 

redox potential 

Test status 

Robustness and intercomparison 

validation in preparation 

In use since 2007 Validated and in operation since 

2004 

Validated and in use since 2009 

Comments: 

Limitation: DOC optional Limitation: Diameter of column, 

when more eluate is needed. 

DOC not considered at the time. 

Limitation: DOC optional. 

Combination of high flowrate and large 

particle size considered unsuitable by 

other EU member states 

Standardized leaching tests for organics*

Similarly, protocols dealing with inorganic and non-volatile organic

substances are available with very similar adjustments as described for

percolation tests. 

Monolith leach tests with option for analysis of organic substances

Release driven by dissolved organic carbon bound organic substances, hence release 

rate can be described when DOC release is known

pH Dependence test with option to analyse organic substances

Dissolved organic carbon (DOC) is a pH dependent parameter and semi- and nonvolatile organic substances are largely controlled by DOC and hence release of these 

organic substances is pH dependent. 

* Observations from EU standardisation activities

Validated national standards for leaching of organics

NEN 7374 (2004) Leaching characteristics - Column test for the 

determination of the leaching of PAH, PCB, OCP and EOX, phenol and 

creosols from granular materials - Solid earthy and stony materials

NEN 7376 (2004) Leaching characteristics - Determination of the 

leaching of PAH, PCB, OCP and EOX, phenol and cresols from building 

and monolithic waste materials with a diffusion test - Solid earthy and 

stony materials

DIN 19528 (2009) Leaching of solid materials - Percolation method for 

the joint examination of the leaching behaviour of inorganic and organic 

substances

C-26
Performance data for leaching of organic contaminants

NEN 7374 (2004) PAH PCB EOX Phenols, cresols

Within lab variability Sr 25 % 15 % 12 % 3 %

Between lab variability SR 42 % 42 % 14 %

DIN 19528 (2009) PAH Naphtalene Anthracene 

Within lab variability Sr 13 % 10 % 12 %

Between lab variability SR 50 % 45 % 45 %

DIN 19528 (2009) Pyrene Chrysene Benzo[a]pyrene 

Within lab variability Sr 10 % 27 % 60 %

Between lab variability SR 45 % 48 % 80 %

Main features of leaching standards for organics*

CEN and ISO Standards are suitable for inorganic and organic substances.

The first and foremost reason is that the basis of testing and the use of test results in 

environmental judgment of release is not fundamentally different.

In many cases information on both inorganic and organic substances is needed. 

Running one test has economic advantages (equipment occupation, cost).

Ecotox testing requires eluates containing all substances of interest.

Material requirements for the equipment and other parts getting in contact with the 

eluate are adapted to meet requirements for both type of substances. Glass column 

and stainless steel connections.

In the column, quartz sand or glass beads are used instead of filters.

Filtration commonly used for inorganic substances is unsuitable for organic 

substances. If needed, centrifugation is prescribed. 

Test limited to non-volatile organic substances at ambient conditions.

* Observations from EU standardisation activities

Non-standardized tests for organics

Static method for porewater analysis (Solid Phase Micro Extraction (SPME), 

Semipermeable Membrane Devices (SPMD), Solid Phase Extraction Disks (SPE 

disks) and Tenax extraction. Applied in the Netherlands for bioavailability of 

organic contaminants in sediments and soils.

Limitation: useful method, but does not provide insight in long term behaviour

Leaching tests for non-volatile organic compounds. Recirculation column 

procedure derived from the CEN/TC292 procedure.

Inconsistent batch test results prompted this development. Test was developed as a 

compliance test procedure. However, results are not easy to interpret. 

Modified diffusion test procedure (Nordtest report TR577)

Same basic test method as defined in CEN/TC292, CEN/TC351 and EPA 1315, but 

modified with a strong sorbing solid or liquid phase to create a zero boundary 

condition. 

Available data on leaching of organics

Dutch, German, Danish and Swedish leaching data

pH dependence 14 samples

Percolation 108 samples

Monolith leaching 82 samples

Ecotox testing in connection with leach testing (Study 

Umwelt Bundes Amt, Germany)

Modelling for partitioning of organic contaminants 

between free, DOC and POM associated forms - Role of 

DOC and POM for organic contaminant mobility.

C-27
Liquid-Solid partitioning and Organic Contaminants

Organic Contaminants (PAHs)

• Solubility is not directly affected by

pH

• Low aqueous solubility

• Partitioning with organic phases

• Complexation with DOC

Complexation with DOC

• Leads to high measured

concentrations

• Quantified by KDOC

• DOC removal by flocculation with

Al2(SO4)3 at pH 6.0

0

100

200

300

400

500

600

700

0

2

4

6

8

10

12

14

2 3 4 5 6 7 8 9 10 11 12 13 14

DOC (mg/L)

 16 PAHs (μg/L)

pH

PAHs

DOC

0

100

200

300

400

500

600

700

0

2

4

6

8

10

12

14

2 3 4 5 6 7 8 9 10 11 12 13 14

DOC (mg/L)

 16 PAHs (μg/L)

pH

PAHsafterflocculation

DOCafterflocculation

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

4 5 6 7 8 9 10 11 12 13 14

Concentration (mg/L)

pH

Anthracene

Benz[a]anthracene

Benzo[k]fluoranthene,BKF

Chrysene,CHR

DissolvedOrganicCarbon

Mineraloil

Sumof16EPAPAH

Phenanthrene

pH Dependent leaching of PAH and DOC for a composite sample of 

Predominantly Inorganic Waste from a lysimeter

Apparent correlation of PAH with

DOC, hence indirect pH 

dependence of PAH leaching

Comparison of PAH and mineral oil leaching based on laboratory, 

lysimeter and field data for landfill

Comparison of PAH leaching from a wide range of 

waste, soil, sediment and construction materials

asphalt, gasworks soil, 

contaminated soil, sifter 

sand from demolition, 

industrial fly ash

coal fly ash, MSWI bottom 

ash, predominantly 

inorganic waste (landfill), 

river sediment, masonry 

aggregate, concrete 

aggregate, reclaimed 

asphalt, porous asphalt 

C-28
Monolith leaching of PAH and biocides from railroad tie, stabilised

waste with organics, roofing felt and treated wood

Results from EU Leaching Test Development for Organics (1)

Adsorption to Material Surfaces

Match contacting surfaces to organic substances of interest

Plastics (including Viton), rubber, PTFE (PAHs adsorb to Teflon)

Glass, stainless steel

Volatilization

Not considered as only semi- and non-volatile organic substances are 

considered. 

Colloid Formation

More colloid formation in a batch test vs column testing

Centrifuge eluate rather than filtration, if at all needed

Eluate Analysis

Always measure pH and DOC. DOC varies as a function of pH and hence 

water insoluble organics associated with DOC have increased leachability 

as pH increases.

Demonstrated higher release from batch vs column

In the context of the development of the ISO standards for Soil a 

comparison was made between batch and column leaching. In 

almost all cases the batch test gave higher release values. 

Explanation higher turbidity and thus higher DOC level in batch vs. 

column. 

Filtration and/or centrifugation

In the German test filtration and centrifugation are not used when 

the turbidity of the solution is below a certain value (FNU). In their 

experience, this is the case for almost all construction products 

and many soils.

19 June 9, 2015 ISCOWA-WASCON 2015 Training LeachXS

Results from EU Leaching Test Development for Organics (2)

Key Concepts

Liquid-Solid Partitioning

• pH – indirectly relevant due to dependence of DOC on pH

• Liquid-Solid Ratio

• Redox – not directly relevant

• Dissolution/Sorption

• Particulate and dissolved organic matter interaction

• Eluate Chemistry

Mass Transport

• Diffusivity

• Surface Area

• Surface Interactions (local equilibrium)

Limitations

• Degradation of organic substances

• Degradation of organic matter and associated DOC formation

• Sorption on many surfaces

• Volatilization

C-29
Ecotox testing in connection with leach testing

(Study Umwelt Bundes Amt, Germany)

In CEN/TC292 Waste characterisation a leaching test for 

ecotox testing was developed.

The validation was done in a project led by UBA (Umwelt 

Bundes Amt, Berlin)

Leaching was carried out by a single step leach test and 

by full characterisation using percolation test PrEN14405 

and pH dependence test EN14429

Partitioning between dissolved and solid phases was 

carried out for dilutions made as part of the ecotox testing 

protocols 

Comparison of PAH content, “availability” and actual 

leachability for Soil (Ecotox validation study UBA, Germany)

Table 4.1 Total PAH in relation to “ available” and leachable PAH at own pH of SOI sample. 

Parameter Total

Concentration ug/l at 

L/S=10 Leached in mg/kg 

% Available % Leachable 

mg/kg pH12 Own pH pH12# Own pH for leaching at own pH 

Anthracene 23.4 5.180 1.521 0.0518 0.0152 0.2214 0.0650

Benzo(a) anthracene 87.2 17.585 1.659 0.1759 0.0166 0.2017 0.0190 

Benzo(a)pyrene 59 9.946 0.656 0.0995 0.0066 0.1686 0.0111

Benzo(b) fluoranthene 78.6 15.114 1.045 0.1511 0.0104 0.1923 0.0133 

Benzo(ghi) perylene 34.7 1.783 0.434 0.0178 0.0043 0.0514 0.0125 

Chrysene 69.4 17.480 1.701 0.1748 0.0170 0.2519 0.0245

Dibenz(ah) anthracene 9.37 0.671 0.858 0.0067 0.0086 0.0716 0.0916 

Fluoranthene 181.6 36.616 10.006 0.3662 0.1001 0.2016 0.0551

Fluorene 4.16 2.637 0.990 0.0264 0.0099 0.6338 0.2381

Phenanthrene 69.1 25.317 0.469 0.2532 0.0047 0.3664 0.0068

Pyrene 146 27.814 6.889 0.2781 0.0689 0.1905 0.0472

# Considered to represent the "available" fraction for leaching 

Simulated partitioning of PAH between particulate and 

dissolved organic matter in a gasworks soil 

Yellow triangles: measurement; blue line: sum of “free” and DOC associated organics.

Aspects in ecotox testing vs. leaching

Only a small fraction ( < 1 %) of the total content of organic substances is 

”available” for leaching. The actual leached quantity at own pH is 

substantially lower. 

Bioavailability changes over the dilution range applied in ecotox testing due 

to several interactions (DOC, Ca levels, salt, repartitioning) causes an 

unexpected increase in observed toxicity by the dilution medium used. 

The DOC association of substances (inorganic and organic) lowers their 

accessibility for organisms and hence their toxic response.

The partitioning between dissolved and particulate organic matter based on 

Koc values from literature reveals a reasonable agreement between 

measured and predicted concentrations in solution (sum of free and DOC 

bound forms).

C-30
Sustainable landfill scenario

Inorganics and organic contaminants

Explanation of 

approach

Example 

results 

Its uses 

The Dutch Ministry of 

Environment and 

Infrastructure

regulates aftercare of 

landfills

• International research into sustainable landfill management has been carried out since

the 1990s.

• The source, here the landfill itself, becomes cleaner, so that fewer harmful substances

are emitted by landfills, and the surrounding soil and groundwater are protected.

• Up till now no proof for effectiveness on a large scale is available.

• To study three full scale landfill as pilots, a scenario based model was used to determine

which emissions from landfills into the soil and groundwater are acceptable.

• The "starting point" in the calculation of the emission testing values is the maximum

allowable concentration of substances in groundwater and surface water next to the

landfills.

• Dilution effects, interaction with soil and soil organic matter as well as dissolved organic

carbon are taken into account. Degradation or organics was not considered.

• With sustainable landfill management, the waste is actively infiltrated with water and air

(active treatment). This causes processes that stimulate the degradation and binding of

the substances in the landfill during a trial period of approximately ten years.

• Emission levels were developed to comply with the environmental quality objectives at a

time to be specified by the relevant authority.

Analysis Approach Used in Dutch Sustainable Landfill Scenario

Example input data (inorganic and organic substances) based on 

percolation test results NEN 7373 (similar to EPA 1314) used in the 

Sustainable Landfill scenario

The overall distribution of a substance between the dissolved and solid phases is expressed as Kd

(linear distribution coefficient), which is composed of two factors, here referred to as Kd1 and Kd2: 

Kd1 is the distribution between substance that is bound to natural organic matter and substance 

dissolved in the water phase according to Appelo & Postma (2005): 

Kd1 = Koc x foc (L/kg) where Koc is the reported Koc value for each substance, and foc is the fraction 

of organic (carbon) substance in the soil. The Koc is obtained from literature. 

Kd2 is the distribution of solid and dissolved natural organic matter between the solid phase and the 

water phase: Kd2 = SOC (kg/kg)/DOC (kg/L) The values for SOC and DOC (solid and dissolved natural 

organic matter, respectively) arise from the organic matter content in the soil per location (STONE 

database) and the assumed concentration of dissolved organic matter in the soil, derived from the 

landfill leachate. 

The overall Kd (distribution coefficient) arises from Kd1 and Kd2 for the transport of organic substances 

in the soil: Kd overall = Kd1 x Kd2/Kd1 + Kd2 

As there are a lot of organic substances, with different transport velocities, these substances are divided 

on the basis of the log Koc per location into classes with approximately the same transport velocity. 

The following processes were not taken into account: 兟 biological degradation (which can further limit 

transport); 兟 gas phase transport (which can greatly speed up transport as it is an important transport 

route particularly for volatile substances); 兟 floating layers or subsidence layers (which can have an 

accelerating or a decelerating effect). The latter are not considered to be of relevance for the 

Sustainable Landfill scenario.

Calculation approach for organics in the Sustainable Landfill Scenario

C-31
Evaluation results (concentration as a function of time in the 

soil solution at 1-2 m depth) Sustainable Landfill Scenario Observations (1)

Validated test methods for organic substances available at national level. 

Validation of tests suitable for organic substances in construction 

products up for validation in 2017, when the robustness work that will 

start in early 2016 is finished (CEN/TC351). 

Standardised tests show systematic release patterns for organic 

contaminants allowing understanding of release mechanisms

Methods have been aimed to deal with inorganic and organic substances 

simultaneously to facilitate ecotox testing of eluates

Observations (2)

The role of dissolved organic matter is important in release of semi- and 

non-volatile organic substances due to their association with DOC

The transport properties are not controlled only by the substance itself, 

but also by the transport properties of DOC

The pH dependence of DOC release is important because of the 

association of organics with DOC impacts organics partitioning and 

transport

Release of organic substances from monolithic products (stabilised

waste and treated wood) is to a large extent controlled by release of 

DOC bound organic substances and thus controlled by DOC release. 

DOC release from porous monolithic materials is about a factor 10 – 15 

slower than soluble salts (e.g. Na+, K+, Cl-

) 

Observations (3)

DOC associated organic substances are not bioavailable for a range of 

organisms and thus have no toxic response (example: gaswork soil UBA 

study)

Partitioning of dissolved organic matter in subfractions (fulvic and humic

substances) may prove important in view of their different binding 

characteristics for organic contaminants

The use of Koc parameters allows the partitioning of organic

contaminants to be estimated between particulate and dissolved organic

matter

Sustainable landfill scenario considers leaching test results in conjunction

with transport, dilution and attenuation to determine leaching test 

thresholds for regulation. 

C-32
References

Standards published by CEN (European standards organisation), ISO 

(International Standards organisation), Dutch Standards Organisation

(NEN) en German Standards Organisation (DIN)

Ecotoxicological characterization of waste – Results and experiences 

from a European ring test. Eds: J. Römbke, R. Becker & H. Moser, 

Springer Science+Business Media, Inc. Norwell (MA). Chapter : Postma

J.F., van der Sloot, H.A. and van Zomeren A. (2009): Ecotoxicological

response of three waste samples in relation to chemical speciation 

modelling of leachates.

E. Brand et al. (2014) Development of emission testing values to assess 

sustainable landfill management on pilot landfills Phase 2: Proposals for 

testing values, RIVM report 607710002/2014

C-33
Office of Solid Waste and Emergency Response

Office or Resource Conservation and Recovery, Waste Characterization Branch

Photo image area measures 2” H x 6.93” W and can be masked by a 

collage strip of one, two or three images.

The photo image area is located 3.19” from left and 3.81” from top of page. 

Each image used in collage should be reduced or cropped to a maximum of 

2” high, stroked with a 1.5 pt white frame and positioned edge-to-edge with 

accompanying images.

LEAF Leach Testing for Inorganic 

Contaminants: What Led to it’s 

Development?

Gregory Helms, ORCR

September 15, 2015

Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

What Led to LEAF Development?

• TCLP is EPA’s regulatory test and most used leaching test.

• Developed to implement the national RCRA regulatory program

(not tailored to be site-specific).

• Based on RCRA def of hazardous waste (“may pose hazard

when improperly managed”).

• Simulates plausible mis-management scenario for waste

disposal (i.e., co-disposal with municipal solid waste).

• Because it is the regulatory test, TCLP is used even when not

required by regulation:

• EPA SAB has twice (1991,1999) expressed concern about over-broad

use of TCLP.

• Conditions at most contaminated sites do not resemble MSW/TCLP 

conditions.

1

Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

What Led to LEAF Development?

• ORCR experienced several program problems

related to use of TCLP in the late 1990s:

• The LDR treatment standard and hazardous waste delisting for K088 

based on TCLP data resulted in environmental releases:

– Arsenic was leaching from the K088 disposal monofill at levels 

more than 100x the TCLP results (monofill leachate pH 13)

– EPA withdrew the delisting and instituted disposal restrictions for 

delisted waste.

• EPA was successfully sued on use of TCPL data to establish the LDR 

standard by an aluminum company.

– The court said that models of the environment must bear a 

reasonable relationship to the situation they are intended to 

represent.

2 Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

What Led to LEAF Development?

• TCLP Program Issues (cont):

• In responding to legal challenges to TCLP use in determining the 

hazardousness of mineral processing wastes, the Agency was urged to 

consider using SPLP instead.

• TCLP was used in the end, but EPA agreed to conduct a review of 

leaching tests and their use in Agency Waste management programs

3

C-34
Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

Superfund Use of Leach Tests for S/S 

Projects

4 Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

What Led to LEAF Development?

• EPA’s Science Advisory Board (SAB) has in the past

expressed concern about the Agency’s use of

Leaching Tests:

– In a 1991 report, the SAB expressed concern about the over-broad 

use of the test, particularly where test conditions did not match site 

conditions.

– SAB expressed concern about several technical aspects of TCLP 

(e.g., colloid formation)

– SAB urged the Agency to develop test methods which would: 

• Consider the significant parameters affecting leaching.

• Consider conditions of the disposal site.

• Be supported by field validation and repeatability studies.

• Be supplemented by leaching and source term modeling.

– In 1999 the SAB reiterated many of the concerns expressed in the 

1991 report.

5

Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

What Led to LEAF Development?

• EPA initiated a program to identify and validate a nextgeneration of leach testing approaches

–Goals in selection of appropriate tests included:

1. General applicability to a broad range of

wastes/secondary materials

2. Consideration of conditions that affect leaching 

3. Flexibility to allow tailoring for a range of applications 

6 Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

What Led to LEAF Development?

• 2003 SAB Consultation

• When LEAF research on CCR leaching was begun, ORCR/ORD

consulted with the SAB about the approach being taken.

–SAB was in particular asked its advice about the relative

importance of the parameters affecting leaching that are 

incorporated into LEAF.

–SAB did not disagree, but noted that other factors are

sometimes important and urged flexibility in testing.

–SAB also urged the Agency to develop leaching tests that

included leaching or organic constituents.

7

C-35
Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

LEAF Addresses Many SAB Concerns

• Most tests (including TCLP & SPLP) assess leaching

potential for a single set of conditions:

• Tests tend to focus in initial conditions; final test leaching

conditions are often unknown.

• However, final test conditions represent conditions under which

leaching actually occurs

• Site conditions can have a significant impact on

leaching:

• Metal solubility and aqueous-solid partitioning vary with pH.

• Infiltration rates vary nationally (varying weather, soil type) 

• Redox conditions can determine which metal salts are present

(and so change solubility).

• Site conditions can change over time.

8 Office of Solid Waste and Emergency Response

Office of Resource Conservation and Recovery, Waste Characterization Branch

Program Use of LEAF 

• Intended for situations where a tailored assessment is

needed, and the conditions differ from TCLP, and TCLP is

not required by RCRA regulations

– Evaluating treatment effectiveness for corrective action/site remediation 

where LDR treatment standards are not triggered

– Hazardous waste delisting

– Assessment of non-hazardous materials for beneficial reuse

– Characterizing potential release from high-volume materials 

• CAMU regulations can allow use of alternatives to TCLP for assessing 

stabilization treatment effectiveness if the alternative more accurately 

reflects conditions at the site that affect leaching. See: 40 CFR 

264.552(e)(4)(iv)(F)

9

C-36
Office of Research and Development

National Risk Management Research Laboratory

Air Pollution Prevention and Control Division

September 16, 2015

Susan Thorneloe, US EPA

Thorneloe.Susan@epa.gov

What is LEAF for inorganics? What lead to its 

development? What was the process and 

timeline for developing and validating the 

methods?

Presentation for USEPA Workshop for Developing Organic Leaching Test 

Methods for Semi- and Non-volatile organic compounds

Provide understanding of work to develop and validate:

EPA Method 1313 Liquid-Solid Partitioning as a Function of Eluate pH 

using a Parallel Batch Procedure

EPA Method 1314 Liquid-Solid Partitioning as a Function of 

Liquid-Solid Ratio (L/S) using an Up-flow 

Percolation Column Procedure

EPA Method 1315 Mass Transfer Rates in Monolithic and 

Compacted Granular Materials using a Semidynamic Tank Leaching Procedure

EPA Method 1316 Liquid-Solid Partitioning as a Function of LiquidSolid Ratio using a Parallel Batch Procedure

Posted as “New Validated Methods” to SW-846 on Aug 2013

Objective

Scrubber

Additive

Filter or Electric Static 

Precipitator (ESP) 

Selective

Catalytic

Reduction

(SCR)

DeNOx

Air

Preheater

Steam

Generator

Flue Gas Desulfurization

(FGD) Scrubber

Coal

Bunker

Range of Technologies in use for Reducing 

Air Emissions at Coal-Fired Power Plants

Coal Additive Refined Coal Flue Gas 

Conditioning

Dry Sorbent 

Injection (DSI)

Activated Carbon 

Injection (ACI)

3

Range of Coal Combustion Residues (CCR) 

Management Scenarios ...

coastal protection

drinking water well landfill road base

agriculture mining

4

contaminated soil

C-37
• Existing leaching tests (i.e., simulation based) did not consider differences in 

materials or environmental parameters (such as pH and liquid-solid ratio) that 

influence leaching behavior

• EPA received comments from EPA’s Science Advisory Board, National Academy 

of Sciences, NGOs and others regarding the deficiencies of existing methods 

(e.g., TLCP) when not applicable or appropriate

• EPA received report form the IG criticizing program that encouraged use of coal 

ash without considering potential impact on human health and the environment 

• Changes occurring to coal fly ash and scrubber residues in response to CAA 

regulations to reduce Hg and other pollutants can change the leachability of Hg 

and other pollutants based on how coal combustion residues are managed by 

disposal or use

• Congressional request to ensure the air pollution control at coal-fired power 

plants are not resulting in transferring pollutants from one medium (air) to another 

(land or water resources)

Drivers for Improved

Leaching Test Methods

Use of LEAF in Source 

Term Development

• Used to evaluate range of fly ashes and scrubber residues to develop material- and sitespecific source terms for land disposal of CCRs

• Data led to EPA’s decision to allow use of coal fly ash for substitute for portland cement for 

encapsulated uses. EPA’s decision was based on use of LEAF data to evaluate potential 

leaching from monoliths where fly ash is used as replacement for cement. 

• “How to” Guidance for use of LEAF data has source term derivations for (1) coal ash used 

as embankment fill; (2) contaminated soil remediation; and (3) solidified waste treatment. 

Expect release in next 6 months. Will be updated as source terms are expanded to other 

applications.

• Continue to see broader use of LEAF by industry, academia, and commercial labs. 

• The EU has developed methods comparable to LEAF for source term In parallel, the EU 

has developed methods comparable to LEAF for source term evaluation. China, Australia, 

Israel, and the EU are adopting comparable methods.

• Once CCR evaluation was completed, OSWER requested that LEAF be validated for 

adoption to SW-846. Over 20 labs were involved using 4 different reference materials for 

each of the 4 LEAF methods. Work began in 2010 and completed in 2013.

6

Leaching Environmental 

Assessment Framework

LEAF is a collection of ...

Four leaching methods

Data management tools

Geochemical speciation and mass transfer modeling 

Quality assurance/quality control

Integrated leaching assessment approaches

More information at http://www.vanderbilt.edu/leaching

7

Leaching Environmental 

Assessment Framework (Cont.)

Designed to identify characteristic leaching behaviors for a 

wide range of materials and associated use and disposal 

scenarios to generate material- and site-specific source terms

Not intended as replacement for TCLP but for use when 

TCLP is not considered applicable or appropriate. Uses 

include

Assessment of materials for beneficial use

Evaluating treatment effectiveness (equivalent treatment 

determination)

Characterizing potential release from high-volume materials

Corrective action (remediation decisions)

8

C-38
LEAF Leaching Tests*

• Equilibrium-based leaching tests

–Batch tests carried out on size reduced material

–Aim to measure contaminant release related 

to specific chemical conditions (pH, LS ratio)

–Method 1313 – pH dependence & titration curve

–Method 1316 – LS dependence

• Mass transport rate-based leaching tests

–Carried out either on monolithic material or compacted granular 

material

–Aim to determine contaminant release rates by accounting for both 

chemical and physical properties of the material

–Method 1315 – monolith & compacted granular options 

• Percolation (column) leaching tests

–May be either equilibrium or mass transfer rate

–Method 1314 – upflow column, local equilibrium (LS ratio)

*Posting to SW-846 Validated Methods completed August 2013

http://epa.gov/wastes/hazard/testmethods/sw846/new_meth.htm 9

LEAF Data Management Tools

Data Templates

–Excel Spreadsheets for Each Method 

• Perform basic, required calculations (e.g., moisture content)

• Record laboratory data

• Archive analytical data with laboratory information

–Form the upload file to materials database

Software for LEAF data management, visualization and processing; 

–Compare Leaching Test Data

• Between materials for a single constituent (e.g., As in two different CCRs)

• Between constituents in a single material (e.g., Ba and SO4 in cement)

• To default or user-defined values indicating QA limits or health-based 

threshold values)

–Export leaching data to Excel spreadsheets

Available at no cost from LEAF project website (http://www.vanderbilt.edu/leaching)

10

Statistical Analysis

Standard Deviations

• Repeatability (within lab deviation)

• Reproducibility (between lab 

deviation)

95% Robust Confidence Limits

• Prediction interval within which 95% 

of mean log10 transformed data 

from a lab would fall

0

0.05

0.1

0.15

0.2

0.25

0 2 4 6 8 10 12 14

As Std Dev [log(mg/L)]

Target pH

Between Labs

Between Labs Nat

Within Labs

Within Labs Nat

ML

MDL 0.01

0.1

1

10

100

0 2 4 6 8 10 12 14

Arsenic (mg/L)

pH

Validation of LEAF Test Methods

MultilabRoundrobin

Testing

Academic,

Commercial,

Governmentand

InternationalLabs

Materials

CoalFlyAsh

ContaminatedSoil

SolidifiedWaste

BrassFoundrySand EPA600/R12/623 EPA600/R12/624

12

C-39
13

Validation Acknowledgements

Participating Labs – Domestic 

• Government

Oak Ridge National Lab

Pacific Northwest National Lab

Savannah River National Lab

U.S. EPA- Research Triangle 

Park, NC

• Academia

Ohio State University

University of Wisconsin –

Madison

University of Missouri – Rolla

Vanderbilt University

• Commercial

ARCADIS-US, Inc.

TestAmerica Laboratories, Inc.

URS Corporation

Other participating labs – international

• DHI (Denmark)

• Energy Research Centre of the 

Netherlands

Support

• Electric Power Research Institute 

(EPRI)

• Recycled Materials Research Center 

(RMRC)

• Tennessee Valley Authority (TVA)

LEAF Methods Focus Group

Validation Lessons Learned

Modifications to Methods 1313 and 1316

• Tolerance for contact time have been added

• Requirement that pH values to be measured within 1 hr after separation 

of solids and liquids due to lack of buffering in aqueous samples

Modifications to Data Templates

• Mandatory information has been highlighted

• Instructions more closely follow method text 

Other Recommendations

• Calibration of pH meters should cover entire pH range to extent possible 

• Reagents should be freshly prepared, stored in vessels of compatible 

materials (e.g., strong alkalis not be stored in borosilicate glass)

• Labs should establish a QC regimen to check the quality of reagent 

water (method blanks are important)

Laboratory-to-Field Relationships

• Providesunderstandingofleaching

assessmentfundamentals

• 10Casesoflargescalefieldanalysis

coupledwithlaboratorytestingfor7

differentmaterials

-Coalcombustionresidues(flyash,

scrubberresidues

-Inorganicwaste(mixedorigin)

-Municipalsolidwaste(MSW)

-MSWincineratorbottomash

-CementstabilizedMSWincineratorflyash

-Portlandcementmortarsandconcrete

EPA600/R14/061 15

LEAF Method Validation Steps 

• Agreements with labs to conduct validation of individual methods

• Obtain or develop samples for analysis

• Prepare and deliver kits with equipment and samples for each lab and

method

• Receive Excel spreadsheets with results from each lab for each

material and method

• Statistical analysis of samples to evaluate inter- and intra- laboratory

variability

• Documentation of results into two reports representing two batch 

equilibrium methods and two mass transfer methods

• Reviews and publication of EPA report

• Posting of validated methods onto SW-846 web site

16

C-40
Conclusions for LEAF Validation

LEAF methods for inorganics 

– have been found to provide data needed for assessing release behavior under range of 

field conditions for use and disposal scenarios 

– can be used to evaluate leaching behavior of a wide range of materials using a tiered 

approach that considers the effect of leaching on pH, liquid-to-solid ratio, and physical form

– were validated working with 20 different labs and posted on the SW846 website as 

validated methods

Research has been coordinated with international community resulting in 

leveraging expertise, data, and helping provide harmonization in leaching methods 

so that comparable data is provided when evaluating use of industrial by-products 

or treatment and remediation effectiveness

Field to lab report showed good comparison between lab and field data using 

geochemical speciation modeling for processes not easily evaluated in lab (i.e., 

oxidation and carbonation). Able to explain leaching behavior and found LEAF is 

good predicator of ultimate fate of inorganics.

17

Supporting Documentation for LEAF Validation

D.S. Kosson, H.A. van der Sloot, F. Sanchez, and A.C. Garrabrants 

(2002) “An integrated framework for evaluating leaching in waste 

management and utilization of secondary materials,” Environmental 

Engineering Science, 19(3), 159-204.

Background Information for the Leaching Environmental Assessment 

Framework Test Methods, EPA/600/R-10/170, Dec 2010

Interlaboratory Validation of the Leaching Environmental Assessment 

Framework (LEAF) Leaching Tests for Inclusion into SW-846: Method 

1313 and Method 1316, EPA 600/R-12/623, Sept 2012

Interlaboratory Validation of the Leaching Environmental Assessment 

Framework (LEAF) Leaching Tests for Inclusion into SW-846: Method 

1314 and Method 1315, EPA 600/R-12/624, Sept 2012

Laboratory-to-Field Comparisons for Leaching Evaluation using the 

Leaching Environmental Assessment Framework (LEAF), EPA 600/R14/061, Sept 2014. 18

Supporting Documentation for use of LEAF to 

evaluate coal combustion residues (CCRs)

S.A. Thorneloe, D.S. Kosson, F. Sanchez, A.C. Garrabrants, and G. Helms 

(2010) “Evaluating the Fate of Metals in Air Pollution Control Residues from CoalFired Power Plants,” Environmental Science & Technology, 44(19), 7351-7356.

Characterization of Coal Combustion Residues from Electric Utilities - Leaching 

and Characterization Data, EPA-600/R-09/151, Dec 2009

Characterization of Coal Combustion Residues from Electric Utilities Using Wet 

Scrubbers for Multi-Pollutant Control, EPA-600/R-08/077, July 2008

Characterization of Mercury-Enriched Coal Combustion Residues from Electric 

Utilities Using Enhanced Sorbents for Mercury Control, EPA-600/R-06/008, Feb 

2006

19

Supplementary Slides on CCR 

Evaluation

20

C-41
U.S. range of observed total content and leaching test results (5.4 

pH 12.4) for 34 fly ash samples and 20 FGD gypsum samples

21

Indicator Values Fly Ash FGD Gypsum

TC (μg/L) MCL

(μg/L)

Total

Content

(mg/kg)

Leaching

Concentration 

(μg/L)

Total Content

(mg/kg)

Leaching

Concentration 

(μg/L)

Hg 200 2 0.1- 1.5 <0.01-0.50 0.01-3.1 <0.01-0.66

Sb - 6 3-14 <0.3-11,000 0.14-8.2 <0.3-330

As 5,000 10 17-510 0.32-18,000 0.95-10 0.32-1,200

Ba 100,000 2,000 50-7,000 50-670,000 2.4-67 30-560

B - 7,000* NA 210-270,000 NA 12-270,000

Cd 1,000 5 0.3-1.8 <0.1-320 0.11-0.61 <0.2-370

Cr 5,000 100 66-210 <0.3-7,300 1.2-20 <0.3-240

Mo - 200 6.9-77 <0.5-130,000 1.1-12 0.36-1,900

Se 1,000 50 1.1-210 5.7-29,000 2.3-46 3.6-16,000

Tl - 2 0.72-13 <0.3-790 0.24-2.3 <0.3-1,100

*IndicatesDWELvalueratherthanMCL.Red textindicateswhereleachingconcentrationsaregreaterthanindicatorvalues

butdoesnotreflectfateandtransportmodeling. FromES&T2010publication.

IndicatorValues:TC=Toxicitycharacteristicvalue;DWEL– drinkingH2Oequivalentlevel;MCL– Maximumcontaminantlevel

Illustration of why LEAF is Needed

22

• COPCsleaching

fromCCRshave

beenfoundto

spanupto4

ordersof

magnitude

• Acceptability

appearstobe

CCRand/oruse

specific

C-42
Existing Tools and Limitations to Address Leaching 

of Organic Species

1 Civil & Environmental Engineering, Vanderbilt University, Nashville, TN 2 Hans van der Sloot Consultancy, Langedijk, The Netherlands

David S. Kosson1

Andrew C. Garrabrants1

Hans A. van der Sloot2

USEPA Workshop on the Measurement of Leaching of Semi- and Non-Volatile Organic 

Compounds 

September 16-17 , 2015, Washington

Leaching Controlling Factors

Physical Factors

Particle size

Flow rate of leachant

Rate of mass transport

Temperature

Porosity

Geometry

Permeability

Hydrological conditions

Chemical Factors

Equilibrium or kinetic 

control

Liquid-solid ratio

Potential leachability

pH

Complexation

Redox

Sorption 

Biological activity

Trace elements

Soluble salts

TOC (@ high pH) DOC

H+

CO2

O2

Erosion

Release

Mechanisms

Wash Off

Dissolution

Diffusion

2

Simulation vs. Characterization

Simulation-based Leaching Approaches

• Designed to provide representative leachate under specified conditions, simulating 

a specific field scenario

• Eluate concentration assumed to be leachate (source term) concentration

• Simple implementation (e.g., single-batch methods like TCLP or SPLP) and

interpretation (e.g., acceptance criteria) 

• Limitations

Representativeness of testing to actual disposal or use conditions?

Results cannot be extend to scenarios that differ from simulated conditions

Characterization-based Leaching Approach

• Evaluate intrinsic leaching parameters under broad range of conditions

• More complex; sometimes requiring multiple leaching tests

• Results can be applied to “what if” analysis of disposal or use scenarios

• Allows a common basis for comparison across materials and scenarios

• Materials testing databases allow for initial screening

3

EPA Method 1310B – EP Toxicity

 Simulation Approach – Designed to mimic co-disposal in sanitary landfill, i.e., 

with municipal solid waste (assumed mismanagement scenario)

 Applicability – inorganic and organic species, volatiles not specified

 Batch, single extraction test (end-over-end mixing)

 Liquid/Solid Ratio – 20 mL/g; Particle size - <9.5 mm or 3.3 cm dia. X 7.1 cm 

cylinder; 24 h contact

 Extractant – DI water + 0.5 N acetic acid added to maintain pH 5±0.2 up to 4 

mL 0.5 N acetic acid

Limitations

 Applicability of the scenario

 Definition of initial conditions, not necessarily end-point conditions (final pH)

 Particle size/monolith extraction time does not necessarily approach equilibrium

4

C-43
EPA Method 1311 - TCLP

 Simulation Approach – Designed to mimic co-disposal in sanitary landfill, 

i.e., with municipal solid waste (assumed mismanagement scenario)

 Applicability – inorganic and organic species, including volatiles

 Batch, single extraction test (end-over-end mixing)

 Liquid/Solid Ratio – 20 mL/g; Particle size - <9.5 mm; 18 h contact

 Extractants – Dilute acetic acid (pH 2.88) or buffered acetic acid (pH 4.93) 

based on initial waste pH screening

Limitations

 Applicability of the scenario

 Definition of initial conditions, not end-point conditions (e.g., final pH); 

treatment frequently designed to titrate test method

 Particle size/extraction time does not necessarily approach equilibrium

 PTFE is allowed apparatus material

5

EPA Method 1312 - SPLP

 Simulation Approach – Designed to mimic contact with synthetic 

preciptation

 Applicability – inorganic and organic species, including volatiles

 Batch, single extraction test (end-over-end mixing)

 Liquid/Solid Ratio – 20 mL/g; Particle size - <9.5 mm; 18 h contact

 Extractants – Dilute 60/40 wt% H2SO4/HNO3 to intial extraction fluid pH 

4.2 or pH 5.0 (based on east or west of Mississippi River) or reagent 

water (wastewater, wastes) 

Limitations

 Applicability of the scenario

 Definition of initial conditions, not end-point conditions (e.g., final pH); 

acidity or alkalinity of material tested overwhelms eluant acidity

 Particle size/extraction time does not necessarily approach equilibrium

6

EPA Method 1320 - MEP

 Simulation Approach – Designed to mimic repetitive precipitation of acid 

rain on an improperly designed sanitary landfill

 Applicability – inorganic and organic species, including volatiles

 Initial EP Toxicity extraction followed by 9 serial extractions (or more) 

with 60/40 wt% H2SO4/HNO3 to pH 3.0 

 Liquid/Solid Ratio – 20 mL/g; Particle size - <9.5 mm; 18 h contact

Limitations

 Applicability of the scenario

 Definition of initial conditions, not end-point conditions (e.g., final pH); 

eluant acidity often negligible compared to waste alkalinity or acidity

 Particle size/extraction time does not necessarily approach equilibrium

 PTFE is allowed apparatus material

7

EPA Method 1330A – Oily Wastes

8

 Procedural determination 

 Applicability – mobile metal concentrations in oily wastes

 Batch, single extraction test (end-over-end mixing)

 2 step soxhlet extraction with tetrahyudrofuran and then toluene on 

dried solids; 

 Extractants – Dilute acetic acid (pH 2.88) or buffered acetic acid (pH 

4.93) based on initial waste pH screening

Limitations

 Interpretation basis??

C-44
A Decision Support System for 

Beneficial Use and Disposal Decisions 

in the United States and Internationally...

Four leaching test methods

Data management tools

Geochemical speciation and mass transfer modeling

Quality assurance/quality control for materials production

Integrated leaching assessment approaches

designed to identify characteristic leaching behaviors 

for a wide range of materials and scenarios.

More information at http://www.vanderbilt.edu/leaching 9

LEAF Leaching Methods*

Method 1313  Liquid-Solid Partitioning as a Function of Eluate pH 

using a Parallel Batch Procedure

Method 1314  Liquid-Solid Partitioning as a Function of LiquidSolid Ratio (L/S) using an Up-flow Percolation 

Column Procedure

Method 1315  Mass Transfer Rates in Monolithic and Compacted 

Granular Materials using a Semi-dynamic Tank 

Leaching Procedure

Method 1316  Liquid-Solid Partitioning as a Function of LiquidSolid Ratio using a Parallel Batch Procedure

*Posting to SW-846 as “New Methods” completed August 2013

10 10

Framework Approach

 Test Methods designed to determine intrinsic leaching characteristics

Availability (fraction of constituent available for leaching under environmental 

conditions over moderate time intervals, 100s of years)

Liquid-solid partitioning (~ equilibrium) function of pH or L/S

Elution curve approximating local equilibrium

Mass transport rate from monolithic materials (e.g., diffusion controlled)

Eluate concentrations assumed to be upper bound leachate concentrations

when consistent with leaching mechanisms and field scenario

Solubility controlled leaching

Percolation (uniform) with local equilibrium

Fundamental relationships and standard mass transport models used to 

estimate leaching/source-term concentrations from laboratory test results

Availability controlled leaching

Water contact frequency and amount (e.g., field L/S or liquid/surface area)

Preferential flow and mass transport, analytical or numerical (reactive mass 

transport including chemical speciation)

Lab-to-field verification

11

Can Approximate Leaching From Sorbed

and NAPL Phases with a First Order 

Expression to Illustrate Dependence on 

Capacity of Each Phase for Pollutant and 

Mass Transfer Rate Constant

a

Ca

t

N

N

t

b

CSORB

t

 aD2

Ca

x2 q

Ca

x

N

N

t

 kLa   CSOL Ca

CSORB

t

 ks CSORB KFCa

NF

 

Solute in NAPL governed by mass transfer to water:

-mass transfer rate constant, kLa

-aqueous solubility, CSOL

-bulk aqueous concentration, Ca

Solute in solid governed by mass transfer to water:

-mass transfer rate constant, ks

-sorbed phase concentration, CSORB

-bulk aqueous phase concentration, Ca

-isotherm parameters, KF, NF

Available or Total

LSP (Eq. leach test) Mass transfer rate test

Courtesy C. Werth, U. Texas

C-45
LEAF and EU Methods

WASCON, Gothenburg, Sweden 13

CEN/TC 345 Soil 

ISO/TC190 Soil CEN/TC 292 Waste CEN/TC 292 WG8 CEN/TC 351+ 60 Product TC's

Test

Soil, sediments, 

compost and 

sludge Waste Mining waste Construction products

pH dependence test ISO/TS21268-4 PrEN14429 PrEN14429 PrEN14429#

PrEN14497 PrEN14497

EPA 1313 * EPA 1313 EPA 1313 EPA 1313

Percolation test ISO/TS21268-3 PrEN14405 PrEN14405 FprCENTS 16637-3

 NEN7373 NEN7373

EPA 1314 * EPA 1314 EPA 1314 EPA 1314

NEN7374 (2004) NEN7374 (2004) NEN7374 (2004)

DIN19528 DIN19528 DIN19528

Monolith test PrEN15863 FprCENTS 16637-2

NEN7375 NEN7375

EPA 1315 * EPA 1315 EPA 1315 EPA 1315

NVN 7376 (2004) NVN7376 (2004)

Compacted granular test NEN7347 FprCENTS 16637-2

EPA 1315 EPA 1315 EPA 1315 EPA 1315

Redox capacity CEN/TS 16660

Acid rock drainage EN15875

Reactive surfaces

ISO/CD12782 

parts 1-5

Vienna 

Agreement

* EPA methods included in SW846 & based on NEN 7348 # Not yet adopted in CEN/TC 351 (very relevant for CPR)

Matrix

Comparing pH Dependence Testing with 

TCLP and SPLP - Arsenic

14

ML

MDL

TCLP Limit

0.0001

0.001

0.01

0.1

1

10

100

1000

2 4 6 8 10 12 14

Arsenic (mg/L)

pH

ML

MDL

TCLP Limit

0.0001

0.001

0.01

0.1

1

10

100

1000

2 4 6 8 10 12 14

Arsenic (mg/L)

pH

Smelter Soil Stabilized Waste

TCLP

SPLP

M 1316

Assessment Approach

C

B

A

B

C

A*

Material Characterization

Constituent Release from 

Application Scenario

Constituent Conc./Release 

at Point of Compliance

DAF or Model Scenario

Use as Source Term

Material Leaching in 

Context of Application2

Threshold

Definition

A

road base

Material Leaching Tests

Broad-based characterization of 

intrinsic leaching behavior 

15

2 from test results or by numerical modeling

Method 1313 Overview

n

chemical

analyses LA LB Ln

n samples

S2 Sn

A B n

S1

0.01

0.1

1

10

100

1000

2 4 6 8 10 12 14 Leachate pH

Copper [mg/L]

Titration Curve and Liquid-solid Partitioning 

(LSP) Curve as Function of Eluate pH

16

Equilibrium Leaching Test

Parallel batch as function of pH

Test Specifications

9 specified target pH values plus natural conditions

Size-reduced material

L/S = 10 mL/g-dry 

Dilute HNO3 or KOH

Contact time based on particle size

18-72 hours

Reported Data

Equivalents of acid/base added

Eluate pH and conductivity

Eluate constituent concentrations

C-46
Method 1313 Rationale and Limitations

 Designed to provide Availability and Liquid-Solid Partitioning as a function of 

pH. Also provides acid/base titration and basis for chemical speciation 

modeling. Focus on end-state conditions (pH, L/S, DOC, etc.).

 Particle size and contact intervals, mixing to approach equilibrium.

 Conceptual paradigm is applicable for organic species.

Limitations for Use with Organics

Availability determination approach not applicable for organics

pH domain beyond the relevant scenario pH not needed

Eluant and mixing conditions do not address potential for deflocculation and 

colloid formation

Provisions for selection of apparatus materials, filtration, sample mass, 

extraction volumes, minimizing volatilization losses are not provided

17

Equilibrium Leaching Test

Percolation through loosely-packed material

Test Specifications

5-cm diameter x 30-cm high glass column

Size-reduced material

DI water or 1 mM CaCl2 (clays, organic materials)

Upward flow to minimize channeling

Collect leachate at cumulative L/S

0.2, 0.5, 1, 1.5, 2, 4.5, 5, 9.5, 10 mL/g-dry

Reported Data

Eluate volume collected

Eluate pH and conductivity

Eluate constituent concentrations

Method 1314 Overview

air lock

eluant collection bottle(s)

(sized for fraction volume)

Luer shut-off

valve

eluant 

reservoir

end cap

end cap

1-cm 

sand

layers

pump

subject

material

Luer shut-off

valve

Luer fitting

Luer 

fitting N2 or Ar 

(optional)

Liquid-solid Partitioning (LSP) Curve as Function of 

L/S; Estimate of Pore Water Concentration

18

Method 1314 Rationale and Limitations

 Designed to provide LSP as a function of L/S (elution curve). Approximates 

initial pore water and linkages between individual species leaching (e.g., 

DOC & chloride complexation, depletion of one species leading to increased 

release of another). 

 Particle size, dimensions, flow rate, to approach equilibrium. Eluant to avoid 

deflocculation.

 Conceptual paradigm is applicable for organic species

Limitations for Use with Organics

Provision for in-situ solid phase extraction not provided

Provisions for selection of apparatus materials, filtration, sample mass, 

extraction volumes, minimizing volatilization losses are not provided

19

Method 1315 Overview

Mass-Transfer Test

Semi-dynamic tank leach test 

Test Specifications

Material forms

monolithic (all faces exposed)

compacted granular (1 circular face exposed)

DI water so that waste dictates pH

Liquid-surface area ratio (L/A) of 9±1 mL/cm2

Refresh leaching solution at cumulative times

2, 25, 48 hrs, 7, 14, 28, 42, 49, 63 days 

Reported Data

Refresh time

Eluate pH and conductivity

Eluate constituent concentrations

1 Sample

n

analytical

samples

A1

L1

A2 An

L2 Ln

t1 tn

or

Monolith

Compacted

Granular

n Leaching Intervals

t2

Flux and Cumulative Release as a Function of 

Leaching Time

Granular

Monolithic

0.001

0.01

0.1

1

10

100

1000

0.01 0.1 1 10 100

Cr Release [mg/m2]

Leaching Time [days]

Availability

MDL

ML

20

C-47
Method 1315 Rationale and Limitations

 Designed to provide maximum release flux (mass transport rate) by 

maintaining dilute boundary condition.

 Closed vessels to minimize atmospheric exchange (CO2, O2)

 Interpretation includes consideration of field scenario boundary conditions

 Conceptual paradigm is applicable for organic species

Limitations

Provision for in-situ solid phase extraction not provided (variants have been 

developed but not standardized)

Provisions for selection of apparatus materials, filtration, sample mass, 

extraction volumes, minimizing volatilization losses are not provided

21

ANS 16.1 – Measurement of Leachability 

of Solidified Wastes

 “...intended for indexing radionuclide release from solidified low-level 

radioactive waste forms in a short-term (5-day) test under controlled 

conditions in a well-defied leachant. It is not intended to serve as a 

definition of the long-term (several hundred to thousands of years) 

leaching behavior of these forms a conditions representing actual 

disposal conditions.”

 Monolithic sample, deionized water eluant, L/SA=10 cm, eluant refresh 

at 2, 7, 24 hr; 2, 3, 4, 5, 19, 47 and 90 days cumulative times.

Limitations

Not intended to be applicable to organic contaminants (inappropriate

specification of test conditions)

22

Method 1316 Overview

Equilibrium Leaching Test

Parallel batch as function of L/S

Test Specifications

Five specified L/S values (±0.2 mL/g-dry)

10, 5, 2, 1, 0.5 mL/g-dry

Size-reduced material

DI water (material dictates pH)

Contact time based on particle size

18-72 hours

Reported Data

Eluate L/S

Eluate pH and conductivity

Eluate constituent concentrations

n

chemical

analyses LA LB Ln

n samples

S2 Sn

A B n

S1

Liquid-solid Partitioning (LSP) Curve as a Function 

of L/S; Estimate of Pore Water Concentration

23

0

20

40

60

80

100

120

0 2 4 6 8 10

Molybdenum [g/L]

LS Ratio [mL/g-dry]

Method 1316 Rationale and Limitations

 	



	
 dw. Provides 

basis to approximate early leachate concentrations and determination of 

availability or solubility controlled leaching.

 Particle size and contact intervals, mixing to approach equilibrium.

 Conceptual paradigm is applicable for organic species.

Limitations for Use with Organics

Eluant and mixing conditions do not address potential for deflocculation and 

colloid formation.

Provisions for selection of apparatus materials, filtration, sample mass, 

extraction volumes, minimizing volatilization losses are not provided.

24

C-48
Why is Relative Hydraulic Conductivity Important?

KS/S << Ksoil

Water percolates through material

Continuous pore area exposed

Release concentrations based on 

Liquid-Solid Partitioning

(local equilibrium)

KS/S ~ Ksoil

groundwater

contaminants leach 

at equilibrium 

groundwater concentration

contaminants transfer 

across external 

surface area

Water is diverted around material

Exposed surface area limited to 

external surface

Contaminant release rate controlled 

by Rate of Mass Transfer

Contaminant release under equilibrium conditions will always 

be greater than under mass transport rate limited conditions 25

Selecting Methods and Data Use

Acceptable

Impact?

Treatment 

Option

Mgmt

Scenario

Fundamental leaching 

properties

Equilibrium data

Site information*

Assessment model

Fundamental leaching 

properties 

Availability data, Equilibrium 

data, Mass Transfer data

Site information*

Assessment model

Material

Yes

Release Estimate

Exit

No Yes

Percolation Flow-around

* Site-specific information or 

Default scenarios

Acceptable

Impact?

Treatment 

Option

Mgmt

Scenario

Fundamental leaching 

properties

Equilibrium data

Site information*

Assessment model

Fundamental leaching 

properties 

Availability data, Equilibrium 

data, Mass Transfer data

Site information*

Assessment model

Material

Yes

Release Estimate

Exit

No Yes

Percolation Flow-around

Acceptable

Impact?

Treatment 

Option

Mgmt

Scenario

Fundamental leaching 

properties

Availability, Equilibrium data, 

Site information*

Assessment model

Fundamental leaching 

properties 

Availability data, Equilibrium 

data, Mass Transfer data

Site information*

Assessment model

Material

Yes

Release Estimate

Exit

No Yes

Percolation Flow-around

* Site-specific information or 

Default scenarios

26

Treatment Effectiveness

Cumulative Release from S/S Treated & Untreated MGP Soil

0.1

1

10

100

1,000

10,000

100,000

0.01 0.1 1 10 100

Leaching Time (days)

S/S Material

Untreated Soil

Total PHE in S/S Material

Total PHE in Untreated Soil

Phenanthrene (PHE) Release

(mg/m2)

Total Content

Soxhlet Extraction

S/S Material

Method 1315 

(modified for organics)

Untreated Soil

Method 1314 

(percolation column)

Site-specific info

relating flowrate to L/S

27

Monolith Diffusion Scenarios

28

Laboratory vs field 

conditions

Variable water contacting 

sequence, chemistry

Saturated or unsaturated

Carbonation, oxidation 

ingress

Coupled degradation 

mechanisms with 

leaching

C-49
Percolation with Mobile-Immobile Zones Scenarios

29

Laboratory vs. field 

conditions

Variable water flow 

rate, chemistry

Effects of preferential 

flow

Percolation with Radial Diffusion Scenarios

30

Laboratory vs field 

conditions

Cracked materials 

or packed beds

Effects of 

preferential flow

Variable water flow 

rate, chemistry

Lab & Field Scenario Rationale and Limitations

 Development of source terms follows a tiered approach, with simple 

approximation (reasonable bounding) used based on mass balance, 

chemical thermodynamic, and mass transport principles.

 More complex models used to provide basis for developing leaching source 

terms under conditions that are not direct applications of laboratory test data 

or simple analytical solutions (e.g., finite bath leaching from monolith, 

evolving boundary conditions and chemistry). Includes consideration of 

sorptive phases, aqueous phase complexation, NOM, DOC, redox, etc.

 Conceptual paradigm is applicable for organic species.

Limitations

Does not include consideration of NAPLs, vapor phase transport, 

biodegradation/transformation.

31

Conclusions

 Measurement of intrinsic leaching characteristics and development of 

source terms based on mass balance, thermodynamic and mass 

transport principles provides a robust leaching assessment framework 

that is applicable to both inorganic and organic species.

 Numerical modeling is required when direct extension of laboratory 

results to field conditions is not applicable and analytical solutions are 

not available.

 A tiered approach to source-term estimation provides for a balance 

between extent of testing, complexity of source-term development, and 

end-user needs.

 Current LEAF test methods do not include specifications specific to 

many classes of organic species. Important factors that are not 

addressed specifically for organics include selection of apparatus 

materials, filtration, sample mass, extraction volumes, minimizing 

volatilization losses, maintaining “dilute” boundary conditions (for 

monoliths). Use in source terms does not address NAPLS and vapor 

phase transport. 

32

C-50