xvEPA
EPA530-R-15-005
United States
Environmental Protection
Agency
Industrial Waste Management Evaluation
Model (IWEM) Version 3.1:
User's Guide
June 2015
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Resource Conservation and Recovery
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IWEM User's Guide Acknowledgements
Acknowledgments
Numerous individuals have contributed to the development of the IWEM software and
documentation since IWEM version 1. At EPA, Mr. Taetaye Shimeles served as Work
Assignment Manager for the current version of the model, providing directions and technical
assistance, and is also a contributing author. Dr. Zubair Saleem, Ms. Ann Johnson, and Mr.
David Cozzie had filled this role for the past versions. A variety of other EPA staff have
provided additional technical guidance and suggestions, including Dr. Peter Grevatt, Dr. Lee
Hofmann, Dr. Colette Hodes, Mr. Richard Kinch, Mr. Jason Mills, Mr. John Sager, Mr. Timothy
Taylor, Ms. Shen-Yi Yang, and Ms. Janvier Young. The EPA has been assisted in the
development of IWEM by several contractors: RTI International, HydroGeoLogic, and Resource
Management Concepts, Inc.
in
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IWEM User's Guide Software Development History and Online Resources
Software Development History
The Industrial Waste Management Evaluation Model (IWEM 3.1) is the latest version of a
ground water fate and transport developed by the U.S. EPA's Office of Resource Conservation
and Recovery (ORCR). IWEM, since its initial development in 2002, has undergone a number
changes and revisions. Some of the changes were done to expand the scope of the model from
modeling just waste management units, but also to evaluate potential contaminants releases from
recycled industrial materials used in beneficial use applications. Additional revisions were also
made to increase the usability the model, and allow greater control over the input parameters for
the user. The changes and revisions made the model more flexible, user friendly as well as
usable by various stakeholders. Brief descriptions of the major changes made to model since its
initial release are presented below.
The original IWEM 1.0 (U.S. EPA 2002a, b) was developed as part of the Guide for Industrial
Waste Management (U.S. EPA, 2002c) to conduct two levels of screening analyses (Tier 1 and
Tier 2) to determine the most appropriate liner design for several types of waste management
units in order to minimize or avoid adverse ground water impacts. In Tier 1, the analysis
reflected national distribution of waste management units and site conditions that affect the fate
and transport of constituents in subsurface media. On the other hand, site-specific parameters
were required for key parameters in the Tier 2 probabilistic analysis. This version was based on
Version 2.0 of the U.S. Environmental Protection Agency's (EPA's) Composite Model for
Leachate Migration and Transformation Products (EPACMTP) code (U.S. EPA, 2003a, b),
which included the vadose-zone and aquifer modules developed under the Multimedia,
Multipathway, Multireceptor Exposure and Risk Assessment (3MRA) framework (U.S. EPA,
1999).1
In 2006, building on version 1, IWEM 2.0 was developed by adding a module to simulate fate
and transport from a new source type—a roadway constructed using recycled industrial materials
(i.e., byproducts). The new source type was restricted to Tier 2 analyses. In addition to the new
roadway source, IWEM 2.0 used the latest version of EPACMTP, Version 2.2, without
modification. EPACMTP Version 2.2 includes non-science related changes to the input and
output streams of EPACMTP Version 2.1 (U.S. EPA 2003c, d).
IWEM 3.0 enhanced the functionality of its predecessor, by introducing a more rigorous
treatment of leaching through the roadway cross section by including ditches, drainage, and
surface runoff as optional elements. The graphical user interface was also modified to
accommodate the improved source type. In addition, two significant revisions were made to the
model, which included the following:
• Tier 1 analysis for waste management units was eliminated. The leachate concentration
threshold values stored in the IWEM database and used for Tier 1 analyses were based on
human health benchmarks (e.g., reference doses and slope factors) that were current as of
2002 when IWEM 1.0 was released. To avoid generating a "protective" liner
1 IWEM 1.0 and EPACMTP 2.0 were developed and tested concurrently, whereas the supporting documentation
for IWEM 1.0 was released prior to EPACMTP 2.0 documentation.
IV
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IWEM User's Guide Software Development History and Online Resources
recommendation based on an out-of-date benchmark, the Agency opted to remove the
Tier 1 analysis option from Version 3.0.
• Built-in human health benchmarks, with the exception of maximum contaminant levels
(MCLs), have been removed from the database.
This decision resulted in two significant changes to the model: (1) only Tier 2 analyses are now
available in the software, so references to Tier 2 and the "tiered approach" were removed from
the software and documentation; and (2) other than MCLs, the user is now required to provide
human health benchmarks for the screening evaluation.
The current IWEM 3.1, replaces IWEM 3.0. IWEM 3.1adds a new module to simulate leaching
from a structural fill to evaluate the beneficial reuse of industrial or combustion byproducts in the
construction of the structural fill. Structural fills evaluated by IWEM include the use of industrial
wastes and related byproducts as substitutes for the earthen materials to provide structural
support for parking lots, roads, airstrips, tanks/vaults, and buildings; construction of highway
embankments and bridge abutments; filling of borrow pits, and other landscape irregularities; and
changing the landscape for development or reclamation projects.
Online Resources
EPA's Nonhazardous Industrial Waste Management tools web page
(http://www.epa.gov/waste/nonhaz/industrial/tools/index.htm) provides links to the Guide for
Industrial Waste Management, IWEM, and EPACMTP. The linked IWEM page provides links to
the model itself as well as this User's Guide and the Technical Background Document.
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IWEM User's Guide Format and Notation
Format and Notation
The main font for this document is 12-point Times New Roman font. The Industrial Waste
Management Evaluation Model (IWEM) command buttons, icons, menu items and other action-
controls are shown in 11-point Arial Narrow font, with small capitals style and with vertical bars
at the beginning and end; for example, |FiLE| and |EVALUATION| are two of the menu items contained
in the IWEM menu bar. When referring to a sequential series of menu selections, such as "click
on File, then click on Open," this sequence of keystrokes is presented as |FlLE|OPEN|.
IWEM screen and dialog box titles are presented in underlined text, and user-entry labels are
using the same format as IWEM menu items and other action-controls.
The IWEM software is organized into screens and dialog boxes and, for easy reference, these
components are labeled using a common numbering scheme. Within the main IWEM program
window, there are a number of screens that are displayed one at a time as you move through an
IWEM analysis. Each of these screens has a title that tells you what part of the IWEM software
you are in; if the IWEM screen is stretched to fill the IWEM program window, then the title bar
containing these titles is located directly beneath the IWEM toolbar. Additionally, within some of
these screens there are several tabbed screens that resemble tabbed file folders. Each of these
tabbed screens has a title (placed on the screen itself) that tells you more specifically what type of
information is being requested or displayed on the screen. We refer to all screens and tabbed
screens in this document simply as screens. Finally, when you use certain options on the Source
Parameters (7), Infiltration (9), and Constituent List (10) screens, dialog boxes are displayed to
allow entry of additional information. Each of these dialog boxes has a title (placed on the title
bar at the top of the dialog box) that identifies the type of information requested.
Although there are other ways to navigate through the IWEM software, it is anticipated that most
users will generally start at the beginning of an analysis and then move through the screens
sequentially using the |NEXT| and |BACK| buttons. In order to facilitate the reporting of user
comments and problems, EPA has organized all IWEM components into one common sequential
numbering scheme according to the order in which they would be displayed in a typical analysis.
Hence, a user will typically see the following sequence of screens and dialog boxes (however,
there are some slight differences in this sequence depending upon the source type and infiltration
option chosen by the user):
• Input screen group (tabbed screens 6 through 13)
• EPACMTP Run Manager located on the Evaluation Screen (screen 14)
• Output tabs (tabbed screens 15 through 18)
• Evaluation Summary Screen (screen 19).
Please note that the screenshots presented in this User's Guide reflect specific monitor and
system settings. Your computer's settings may be different, so you may need to use the sliders
that appear as necessary on the right and bottom edge of the IWEM windows in order to see the
entire screen.
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IWEMUser's Guide
Acronyms
Acronyms
AC Asphaltic concrete
Agency U.S. Environmental Protection Agency
CAS Chemical Abstract Service
CCL Compacted clay liner
CCR Coal combustion residual
DOT Department of Transportation
EPA U.S. Environmental Protection Agency
EPACMTP EPA's Composite Model for Leachate Migration with Transformation Products
FBC Fluidized bed combustion
FGD Flue gas desulfurization
GCL Geosynthetic clay liner
GM Geomembrane
GUI Graphical user interface
Guide The Guide for Industrial Waste Management
HBN Health-based number
HCFA High carbon fly ash
HTML Hypertext Markup Language
IWEM Industrial Waste Management Evaluation Model
Kd Soil-water partition coefficient
Koc Organic carbon partition coefficient
LAU Land application unit
LF Landfill
MB megabyte
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
MINTEQA2 EPA's geochemical equilibrium speciation model for dilute aqueous systems
Mn/DOT Minnesota Department of Transportation
MnRoad Minnesota Road Research Facility
MPCA Minnesota Pollution Control Agency
ORCR Office of Resource Conservation and Recovery
PBGM Prefabricated bituminous geomembrane
PCC Portland cement concrete
PP Polypropylene
RAM Random access memory
RCRA Resource Conservation and Recovery Act
RGC Reference ground water concentration
RMRC Recycled Materials Resource Center
RPM recycled pavement materials
RPM/FA recycled pavement materials with fly ash
RSL Regional Screening Level
SF Structural fill
SI Surface impoundment
SPLP Synthetic Precipitation Leaching Procedure
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IWEMUser's Guide
Acronyms
STORE! EPA's Data Storage and Retrieval System, National Water Quality Database
TBD IWEM 3.1 Technical Background Document (U.S. EPA, 2015a)
TCLP Toxicity Characteristic Leaching Procedure
WMU Waste management unit
WSH Washington State Highway
WP Waste pile
Units of Measure
This User's Guide uses the following abbreviations for standard units of measures; these may be
found in combination. In some instances, general units (e.g., length per time) may be used and in
others, specific units (e.g., m/sec). Superscripts indicate the unit is squared (e.g., m2) or cubed
(e.g., m3).
Specific units:
|j,g microgram
cm centimeter
day day
g gram
ha hectare
hr hour
kg kilogram
km kilometer
L liter (if used with other specific
units, as mg/L)
m meter
mg milligram
min minutes
mL milliliter
mm millimeter
mo month
sec second
yd yard
yr year
General units:
L
M
M/L3
M/M
General unit for length (if used with
other general units, as M/L3)
General unit for mass
General unit for mass concentration
(mass per length cubed)
General unit for mass fraction (mass
per mass)
General unit for time
Common Conversion Factors
1 acre
1 ha
1ft2
1 mile
lyd
1ft
1 in
1 m/sec
1 cm/sec
1 ft/sec
1 ft/yr
1 in/yr
1 gal/ft2/day
4,047 m2
10,000m2
0.093 m2
1,609m
0.914m
0.305m
0.0254m
31,536,000 m/yr
315,576 m/yr
9,612,173 m/yr
0.305 m/yr
0.0254 m/yr
14.89 m/yr
Vlll
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IWEM User's Guide Table of Contents
Table of Contents
Acknowledgments iii
Software Development History iv
Online Resources v
Format and Notation vi
Acronyms vii
Units of Measure viii
1. Introduction 1-1
1.1 The IWEM Software 1-1
1.2 System Requirements and Software Installation 1-2
1.2.1 System Requirements 1-2
1.2.2 Software Installation 1-3
1.3 Organization of This User's Guide 1-9
2. IWEM Overview 2-1
2.1 What Does the Software Do? 2-1
2.1.1 IWEM Evaluation 2-2
2.1.2 Detailed Site Assessment 2-3
2.2 IWEM Software Components 2-4
2.2.1 IWEM User Interface 2-4
2.2.2 Source Release Modules 2-4
2.2.3 EPACMTP Fate and Transport Model 2-8
2.2.4 IWEM Databases 2-11
2.3 Assumptions and Limitations of Ground Water Modeling Using IWEM 2-11
3. Running the IWEM Software 3-1
3.1 How Do I Start the IWEM Software? 3-1
3.2 What Are the Key Features of the IWEM Software? 3-1
3.2.1 General User Interface Features 3-1
3.2.2 What is the Constituent Properties Browser? 3-3
3.2.3 How Do I Navigate Through the IWEM Software? 3-5
3.2.4 How Do I Save My Work? 3-8
3.2.5 How Do I Get Help If I Have a Problem or a Question? 3-10
3.2.6 How Do I Begin Using the IWEM Software? 3-12
3.2.7 How Long Will IWEM Run? 3-12
3.3 Introductory Screens (Screens 1 through 5) 3-13
3.4 Entering Inputs 3-16
3.4.1 Input: Source Type (Screen 6) 3-16
3.4.2 Input: Source Parameters (Screen 7) 3-17
3.4.3 Input: Subsurface Parameters (Screen 8) 3-31
3.4.4 Input: Infiltration (Screen 9) 3-33
3.4.5 Input: Constituent List (Screen 10) 3-41
3.4.6 Input: Constituent Properties (Screen 11) 3-51
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3.4.7 Input: Reference Ground Water Concentrations (Screen 12) 3-53
3.4.8 Input: Input Summary (Screen 13) 3-55
3.5 Running an IWEM Evaluation: Run Manager (Screen 14) 3-59
3.6 IWEM Results 3-62
3.6.1 Evaluation Summary: Summary Results Screen (Screen 15) 3-62
3.6.2 Output (Details) (Screens 16, 17, and 18) 3-63
3.6.3 Evaluation Summary (Screen 19) 3-65
3.6.4 Save and Exit 3-67
4. Understanding Your IWEM Input Values 4-1
4.1 Overview 4-1
4.1.1 Default Values for Missing Data 4-1
4.1.2 How IWEM Handles Infeasible User Input Parameters 4-1
4.2 Source Parameters 4-2
4.2.1 WMU Parameters 4-2
4.2.2 Structural Fill Source Parameters 4-9
4.2.3 Roadway Source Parameters 4-11
4.3 Fate and Transport Parameters 4-21
4.3.1 Subsurface Parameters 4-21
4.3.2 Hydrologic (Infiltration and Recharge) Parameters 4-27
4.4 Waste Constituents and Constituent Parameters 4-31
4.4.1 Constituent Selection and Concentrations 4-31
4.4.2 Physical and Constituent Properties 4-32
4.4.3 Reference Ground water Concentrations 4-35
5. Understanding Your IWEM Results 5-1
5.1 IWEM Recommendations for WMUs 5-1
5.2 IWEM Recommendations for Structural Fills and Roadways 5-2
6. References 6-1
Appendix A. IWEM Constituents
Appendix B. WMU Example
Appendix C. Roadway Examples
Appendix D. Structural Fill Example
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IWEM User's Guide Table of Contents
List of Tables
2-1. IWEM WMU and Liner Combinations 2-1
3-1. WMU Source Input Parameters 3-18
4-1. IWEM Input Parameters: WMU 4-4
4-2. IWEM Input Parameters: Structural Fills 4-9
4-3. IWEM Input Parameters: Roadway Source Geometry 4-12
4-4. Manning'sn for Typical Roadside Channels (Chow, 1959) 4-19
4-5. IWEM Input Parameters: Subsurface Parameters 4-22
4-6. IWEM Input Parameters: Hydrologic (Infiltration and Recharge) Parameters 4-28
4-7. IWEM Input Parameters: Constituent Source Concentration Parameters 4-31
4-8. IWEM Input Parameters: Chemical Properties Parameters 4-33
4-9. IWEM Input Parameters: Reference Ground water Concentrations 4-35
List of Figures
2-1. Sample screen from the IWEM GUI 2-4
2-2. Atypical roadway with a recycled-material segment 2-6
2-3. Atypical cross section of aroadway 2-6
2-4. Modules of IWEM corresponding to multiple roadway-source strips 2-7
2-5. An example of layering in road way-source strips 2-7
2-6. Conceptual view of aquifer system modeled by EPACMTP 2-9
3-1. General IWEM screen features 3-2
3-2. Constituent Properties Browser 3-4
3-3. Example IWEM screens identifying several types of controls 3-7
3-4. IWEM online help 3-10
3-5. Introductory screens 3-14
3-6. Input: Source Type (6) 3-16
3-7. Input: Source Parameters (7) for WMU sources 3-19
3-8. Input: Source Prameters (7) for structural fill sources 3-20
3-9 Input: Location of Well With Respect to Roadway (7a) 3-22
3-10. Input: Source Parameters (7) for roadways: Overview 3-23
3-11. Input: Source Parameters (7) for roadways: Geometry 3-25
3-12. Input: Source Parameters (7) for roadways: Layer properties 3-27
3-13. Input: Source Parameters (7) for roadways: Ditch properties 3-28
3-14. Input: Source Parameters (7) for roadways: Drain properties 3-29
3-15. Input: Source Parameters (7) for roadways: Flow Characteristics 3-30
3-16. Input: Subsurface Parameters (8) 3-31
3-17. Input: Infiltration (9) for WMUs 3-34
3-18. Input: Climate Center List (9a) 3-35
3-19. Input: Infiltration (9) for Roadways 3-36
3-20. Default roadway strip infiltration dialog 3-38
3-21. Input: Constituent List (10): Select Constituents 3-41
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3-22. Input: Constituent List (10): Enter Leachate Concentrations for WMUs and
structural fills 3-43
3-23. Input: Constituent List (10): Enter Leachate Concentrations for Roadway Strips 3-45
3-24. Input: Enter New Constituent Data (lOa) 3-47
3-25. Input: New Constituent Data (1 Ob) 3-48
3-26. Input: Add New Reference (lOc) 3-49
3-27. Input: Constituent Properties (11) 3-50
3-28. Input: Reference Ground Water Concentrations (12) 3-52
3-29. Input: Reference Ground Water Concentrations: Edit HBNs (12a) 3-53
3-30. Input: Input Summary (13): WMUs 3-55
3-31. Input: Input Summary (13) -Roadways 3-56
3-32. Evaluation: Run Manager (14) 3-58
3-33. Evaluation: EPACMTP dialog box displayed during model execution 3-59
3-34. Output (Summary): Summary Results (15) 3-61
3-35. Output (Details): Results (16) 3-63
3-36. Evaluation Summary (19) 3-64
4-1. WMU types modeled in IWEM 4-3
4-2. WMU with base below ground surface 4-6
4-3. Position of the modeled well relative to the WMU 4-8
4-4. Atypical roadway with a recycled-material segment 4-11
4-5. Sample road design cross-section 4-11
4-6. Diagrams used by IWEM to specify roadway geometry 4-14
4-7. Example roadway source diagram 4-15
4-8. Example of invalid receptor location after geometric transformation 4-16
4-9. Locations of IWEM climate stations 4-29
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IWEM User's Guide Introduction
1. Introduction
This document describes how to use the Industrial Waste Management Evaluation Model version
3.1 (IWEM 3.1). IWEM is a ground water screening model developed by the U.S. Environmental
Protection Agency's (EPA's) Office of Resource Conservation and Recovery (ORCR)—formerly
the Office of Solid Waste—for the management of non-hazardous industrial wastes. A
companion document, the Industrial Waste Management Evaluation Model version 3.1: Technical
Background Document (U.S. EPA, 2015a), provides technical background information. EPA
strongly recommends that you take the time to understand the technical background of IWEM
before using the model to make the best use of this program.
The objective of this User's Guide is to provide the information necessary to perform an IWEM
evaluation. The rest of this section provides an overview of the software (Section 1.1), system
requirements and instructions for installing the software (Section 1.2), and the organization of
the rest of the User's Guide (Section 1.3).
If you have downloaded a copy of the User's Guide, you can open and read it on-screen while the
IWEM software is running on your computer. You may, however, find it easier to use IWEM's
online help or to print out a copy of the User's Guide and refer to this hard copy while you are
using the software.
1.1 The IWEM Software
IWEM is a ground water screening model that uses hydrogeological settings, source
characteristic, and leachate concentrations to evaluate and recommend the type of liner system
that would be appropriate for industrial waste disposal facilities, or to evaluate the
appropriateness of the beneficial use of industrial materials in structural fills and roadways. In the
case of Waste Management Units (WMUs) - landfills, waste piles, surface impoundment, and
land application units - this software helps you compare the ground water protection afforded by
various liner systems for WMUs with the anticipated waste leachate concentrations, so that you
can determine the minimum liner system required to be protective of human health and ground
water resources. In the case of beneficial use of industrial materials in structural fills or roadways,
it can help you determine whether or not the reuse of industrial materials in structural fills or
roadways is appropriate.
The anticipated users of the IWEM computer program are managers of proposed or existing
units, state regulators, interested private citizens, and community groups. For example:
• Managers of a proposed unit could use the software to determine what type of liner
would be appropriate for the particular type of waste that is expected at the WMU and the
particular hydrogeologic characteristics of the site.
• Managers of an existing unit could use the software to determine whether or not to
accept a particular waste at that WMU by evaluating the performance of the existing liner
design.
• Managers of a structural fill or roadway project could use the software to determine an
appropriate fill or roadway design incorporating industrial waste materials.
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IWEM User's Guide Introduction
• State regulators could use the software in developing permit conditions for a WMU or
deciding whether to allow the use of industrial materials in a particular structural fill or
roadway design.
• Interested members of the public or community groups could use the software to
evaluate a particular WMU, a structural fill design, or a roadway design, and participate
during the permitting process.
An IWEM analysis is a location-based screening analysis that uses a limited set of the most sensitive
waste- and site-specific data to model the fate and transport of waste constituents through
subsurface soils, ground water, and to a receptor well.l The outcome of the analysis is a liner
recommendation for WMU that protects human health and the environment, or a determination
on the appropriateness of reusing industrial materials in a structural fill or a roadway. As with all
modeling, the model outputs, interpretation of the results, and the recommendations should be
taken with the consideration of the assumptions underlying the model and the adequacy of the
input data. The user should familiarize themselves with the limitations and assumptions of the
model (discussed in Sections 3 and 4 of the Technical Background Document) for appropriate
use of the tool.
The unique aspect of the IWEM software is that it allows you to perform screening analyses and
obtain recommendations with minimal data requirements. However, in some cases, this may not
be sufficient, and a comprehensive and detailed site assessment will be needed. Such an
assessment cannot be done using IWEM. If you are interested in conducting a more detailed
analysis, you should consult with the appropriate state agency for information regarding the
selection of an appropriate ground water fate and transport model.
1.2 System Requirements and Software Installation
1.2.1 System Requirements
The IWEM software is designed to run under the Microsoft Windows operating system. The
minimum system requirements for IWEM 3.1 are:
• 1586, Pentium, or compatible processor-based personal computer (Pentium HI @ 500
MHz or greater is recommended)
• 128 MB of RAM
• At least 100 MB of available hard disk space
• A printer for generating hard-copy reports.
The IWEM 3.1 software and installation package are compatible with the following
combinations of Windows operating system:
• Windows XP Professional SP3
• Windows Vista Pro (64-bit, 32-bit)
• Windows 7 Pro (64-bit, 32-bit)
• Windows 8 (64-bit).
1 In IWEM, the term "well" is used to represent an actual or hypothetical ground water monitoring well or drinking
water well, downgradientfrom a WMU or roadway source.
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IWEM User's Guide Introduction
If you encounter any problems installing or running IWEM installation, and you are using a
version of Windows not on the list above (e.g., XP 2002), visit the Microsoft Support web site at
http://support.microsoft.com, and click on the |RUN WINDOWS UPDATES| link and follow the prompts
to download the latest updates to your version of Windows. IWEM may run fine on older
versions of Windows, but has not been tested for compatibility with them.
If your operating system version is up-to-date and you still encounter problems installing or
running the IWEM software, please contact the Resource Conservation and Recovery Act
(RCRA) Information Center in any of the following ways:
E-mail: rcra-docket@epa.gov
Phone: 703-603-9230
Fax: 703-603-9234
In person: Hours: 8:30 am to 4:30 pm, weekdays, closed on Federal holidays
Location: WJC West Building
1301 Constitution Avenue, NW
Room 3334
Washington, DC 20004
Mail: U.S. Environmental Protection Agency
EPA Docket Center
RCRA Docket, Mail Code 2822IT
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
When contacting the RCRA Information Center, please cite RCRA Docket number: F1999-
IDWA-FFFFF.
1.2.2 Software Installation
To use the IWEM software, you must download the software from the EPA's non-hazardous
industrial waste website (http://www.epa.gov/industrialwaste/ - look for a link to Tools) and
install it on your hard-drive. Depending on the security settings of your operating system, if your
computer is connected to a network, this software may need to be installed (and any previous
version uninstalled) by someone with administrator privileges. Instructions for installing and
uninstalling the program are provided below. Any updates to these instructions are located on the
website. If you have difficulty implementing the instructions below, please see your network
administrator for help, or contact the RCRA Information Center as explained in Section 1.2.1,
System Requirements.
The steps for installing and using IWEM 3.1 are as follows:
• Step A - Uninstall Previous Installation of IWEM 1.0 or 2.0
Step B - Install IWEM 3.1.
If IWEM is not currently installed on your system, begin with Step B.
Step A - Uninstall Previous Installation of IWEM
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IWEM User's Guide Introduction
To ensure that the all of the supporting software components are up to date and compatible with
IWEM 3.1, you must uninstall any previous installations of IWEM before installing the new
version. To uninstall a previous installation (note that differences for Windows 7 are shown in
parentheses):
1. Click on the Windows |START| button in the extreme lower left corner of your screen.
2. Select |SETTINGS|, and then select (CONTROL PANEL] (for Windows 7, select (CONTROL PANEL]
directly).
3. Double-click on (ADD/REMOVE PROGRAMS] (for Windows 7, select (PROGRAMS AND FEATURES]).
4. Select |IWEM|, and then click on the |CHANGE/REMOVE| button (for Windows 7, select the
|UNINSTALL| button at the top of the software list).
5. The IWEM Uninstall screen will appear. If IWEM is currently running, please close it
before proceeding. If you are ready to uninstall, click |NEXT|, otherwise click |CANCEL|. The
uninstaller will begin removing IWEM. Click |Finish| when the process is complete. Note:
A dialog box will appear during the uninstall process that will ask if you want to Remove
Shared Components. These are system files that are specific to IWEM and can be
deleted—select |YES TO ALL|.
6. If you do not encounter any un-installation problems, the IWEM program will be
removed from the list of programs on the |ADD/REMOVE PROGRAMS] dialog box, and you can
proceed to Step B, Install IWEM 3.1. However, if you do experience un-installation
problems, please see your computer system administrator for help, or contact the EPA
Docket Center, as explained in Section 1.2.1, System Requirements, of this document.
Step B - Install IWEM 3.1
The following steps provide instructions for installing IWEM 3.1:
1. Close all applications, such as word processing and e-mail programs. If you
encounter any problems while installing IWEM 3.1, please contact your System
Administrator for help. It is possible that a conflict with virus protection software may be
responsible, or you may not have the correct user permissions to install software on your
computer. If you do not have a System Administrator, and you choose to close or disable
virus protection software, please do so ONLY after obtaining a copy of the setup file from
the Internet. Once you have installed IWEM 3.1, restart or enable your virus protection
software.
2. Download the IWEM 3.1 installation file. The file can be found here:
http://www.epa.gov/epawaste/nonhaz/industrial/tools/iwem/index.htm. To download it,
go to Download Model Files and User's Guide, then click on the file name
(IWEM_Installation.exe). If you are asked if you want to run or save the file, select Save.
You may be able to specify a location to save it to (in which case, the Desktop is a
convenient location) or it may be saved to a default download location.
3. Run the IWEM setup file. Navigate to where the file was downloaded and double click
on the file IWEM_Installation.exe to run the installer. Don't forget to be sure all other
applications have been closed first.
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IWEMUser's Guide
Introduction
a. The IWEM Welcome screen then
appears. Click the |NEXT| button.
Remember to un-install any previous
versions of IWEM before proceeding.
If you need to do this, click on the
|CANCEL| button. Otherwise, click the
|NEXT| button.
£, IWEM Setup
To install IWEM 3.1, you must agree
to the terms of the licensing
agreement. Please read the agreement,
select |l AGREE...| and click the |NEXT|
button.
g IWEM Setup
Welcome to the installer for IWEM 3.1 Beta.
It is strongly recommended that you exit all
Windows programs before continuing with this
installation.
Ifyou have any other programs running, please
click Cancel, close the programs, and run this
setup again.
Otherwise, click Next to continue.
Note
Ifyou have previously installed an earlier version
of IWEM. you should un-install that version prior to
proceeding with this installation.
~-
This product is provided under the following *
agreement which identifies what you may do rz~i
with this product and contains limitations on
warranties and/or remedies. This license is
granted bythe US Environmental Protection
Agency.
LICENSE
Installing, copying, or otherwise using this
product indicates your acknowledgment that
you have read this license and agree to its
terms. Ifyou do not agree with the terms of this
license, please return this product to EPA.
I agree to the terms of this license agreement
'.»• I do not agree to the terms of this license agreei
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IWEMUser's Guide
Introduction
d. Enter your name and company name
and click the |NEXT| button.
f.
The next screen provides information
on installation location for the IWEM
files. You will have an opportunity to
change the default install location on
the next screen. Please read this and
then click the |NEXT| button.
f!,, IWEM Setup
The installation software is designed
to auto-detect the C:\Users\Public\
Documents folder for the default
install location. If you want to change
the install location, click the |CHANGE|
button and specify a different
directory, or simply type the location
in the text box You must choose a
location where you have
read/write/create privileges! If you
install the software to a folder where
you do not have these privileges, you
may be unable to run IWEM. Click
the |NEXT| button to proceed with the
IWEM installation process.
IIIlteiEI]
In orderto run the IWEM software, a user must
have read/write/create privileges in the IWEM
software directory. Installing the software to a
folder for which most users do not have these
privileges may result in an inability to execute
the program
The default installation location is C:\Users
\Public\Documents\IWEM. Some
organizations lock local users out of the
required privileges in C:\Users\Public
\Documents and any subdirectories. If you
are using an administrator account to install
this package for another user, please
considerthese requirements when you select
the install folder on the next screen. If your
local user accounts do not have sufficient
The software will be installed in the folder listed
below. To selects different location, eithertype in
a new path, or click Change to browse for an
existing folder.
Install IWEM to:
C:\Users\Public\Documents\IWEM
Space required: 521.3 MB
Space available on selected drive: 222.58 GB
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IWEMUser's Guide
Introduction
Choose where to put the IWEM
shortcut and whether to make IWEM
available only to you or to all users of
the computer. Then click the |NEXT|
button to proceed with the IWEM
installation process.
h. Choose whether to create an IWEM
shortcut on your desktop. Then click
the | NEXT| button.
The next screen summarizes your
selections on the previous screens. If
you are happy with your selections up
to this point, click the |NEXT| button to
install the IWEM software to your
hard drive. Otherwise, click the |BACK|
button to change your installation
settings.
, IWEM Setup
The shortcut icons will be created in the folder
indicated below If you don'twantto use the default
folder, you can either type a new name, or select
an existing folderfrom the list
Shortcut Folder:
Install shortcuts for current user only
Make shortcuts available to all users
IIIlteiEI]
Do you want to create a shortcut to IWEM on your
desktop?
The installer now has enough information to install
IWEM on your computer.
The following settings will be used:
Install folder:
C:\Users\Public\Documents\IWEM
Shortcutfoider IWEM
Please click Next to proceed with the installation.
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IWEMUser's Guide
Introduction
k.
The next screen tracks the progress of
the installation of IWEM 3.1.
Once the software has installed, you
will have the option to view the Read
Me file. Click on the (READ ME| button
to view the file. When you are done,
click on the |NEXT| button.
If the installation was successful,
click on the |FlNISH| button to
complete the installation. On some
newer operating systems (Windows 7
64-bit, for example) you may be
prompted to reboot your system.
Please follow the prompts to ensure a
complete installation.
r?, IWEM Setup
IWEM contains context-sensitive help. At any point
while the program is running, press the Fl key for
help regarding the current operation.
Installing Files...
C:\Program Files
Cancel
head Mel ^ore recent information may be
available in the README.TXT file.
Click the Read Me button to view this
file now
Installation Successful
The IWEM 3.1 Beta installation is complete.
Thank you for choosing IWEM!
Please click Finish to exit this installer.
If you experience installation problems, please see your computer system administrator for help,
or contact the EPA Docket Center, as explained in Section 1.2.1 of this document.
Launching IWEM
After installation, you can launch the program by choosing |START| PROGRAMS] (at the
lower left corner of the screen) and then choosing |IWEM|. Alternatively, if you can
created a short-cut to the |IWEM| program on your Windows desktop, you can be launch
E
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IWEM User's Guide Introduction
IWEM by double-clicking the |IWEM| icon (shown at right) on your desktop.
1.3 Organization of This User's Guide
This User's Guide is organized as follows:
• Section 2 provides an overview of the IWEM software;
• Section 3 provides detailed instructions on how to run the IWEM software, and guides
you step-by-step through WMU and roadway evaluations;
• Section 4 presents background information to assist in understanding the input values;
how they affect the model evaluation; and how to obtain input values
• Section 5 presents background information to assist in understanding the IWEM results;
• Section 6 lists all references cited;
• Appendix A presents the list of waste constituents included in IWEM;
• Appendix B presents the example problem and reports for WMU evaluations;
• Appendix C presents the example problem and reports for roadway evaluations; and
• Appendix D presents the example problem and reports for structural fill evaluations.
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IWEM User's Guide Introduction
[This page intentionally left blank.]
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IWEMUser's Guide
IWEM Overview
2. IWEM Overview
The IWEM software developed by the EPA provides a screening level analysis for the ground
water pathway. Based on the user's inputs and assumptions, the analysis produces
recommendations on the type of liner to be used in a WMU that is protective, and/or whether the
beneficial reuse of industrial materials in structural fills or roadways is appropriate or not. The
model is a Windows-based program with a user-friendly interface, and will operate on any
standard personal computer using windows operating system. This section describes the IWEM
evaluation process (Section 2.1), the model structure and components (Section 2.2), and some of
the key assumptions and limitations behind the model (Section 2.3).
2.1 What Does the Software Do?
The IWEM software is consisted of six source modules to simulate the migration contaminants
from a source location to a ground water well. Four of these modules are designed to help you
identify a liner design for four different types of RCRA Subtitle D (non-hazardous) WMUs:
landfills, waste piles, surface impoundments, and land application units. The remaining two
modules are designed to help you determine whether the beneficial reuse of industrial material in
a structural fill or roadway will be appropriate. IWEM arrives at these conclusions by comparing
the model estimated ground water concentration at a well - calculated using the leachate
concentration enter by the user for each waste constituent2 and a ground water fate and transport
model - to a benchmark selected by the user. If the estimated ground water concentration is less
than the benchmark, the modeled scenario is considered "protective" (or, "appropriate" in the
case of beneficial use) with respect to that benchmark. These conclusions should be taken with
the consideration of the underlying model assumptions and the adequacy of the input data.
For WMUs, IWEM will evaluate the protectiveness of ground water concentrations relative to
your benchmark(s) for three standard liner scenarios: no liner, clay liner, and composite liner.
Not all liner scenarios apply to all WMU types; Table 2-1 shows the combinations of WMUs
and liners that are represented in IWEM. For land application units, only the no-liner scenario is
evaluated because liners are not typically used at this type of facility.
Table 2-1. IWEM WMU and Liner Combinations
WMU Type
Landfill
Waste Pile
Surface Impoundment
Land Application Unit
Liner Scenario
No Liner (in-situ soil)
^
S
^
^
Single Clay Liner
^
S
S
X
Composite Liner
^
^
^
X
^= applies to WMU * = does not apply to WMU
The estimated leachate concentration means the concentration, in milligrams per liter (mg/L), of each constituent of
concern that is expected to be present in the leachate after emplacement of the waste in a WMU or use of the waste
in a structural fill or roadway. Typically this concentration is measured using a laboratory leachate test.
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IWEMUser's Guide
IWEM Overview
The IWEM user can save and retrieve evaluations so that they can be archived or retrieved later
and modified. IWEM also has report generation capabilities to document in hard copy the input
values and results.
2.1.1 IWEM Evaluation
About Monte Carlo Analysis
Monte Carlo analysis is a computer-based
method of analysis developed in the 1940s that
uses statistical sampling techniques to obtain a
probabilistic approximation to the solution of a
mathematical equation or model. The name refers
to the city on the French Riviera that is known for
its gambling and other games of chance. Monte
Carlo analysis is increasingly used in risk
assessments where it allows the risk manager to
make decisions based on a statistical level of
protection that reflects the variability and/or
uncertainty in risk parameters or processes,
rather than making decisions based on a single
point estimate of risk. For further information on
Monte Carlo analysis in risk assessment, see the
EPA's Guiding Principles for Monte Carlo Analysis
(U.S. EPA, 1997).
An IWEM evaluation utilizes information on the
source (WMU, structural fill, roadway) location and
other site-specific data enabling you to perform an
assessment that reflects key, sensitive site
conditions. If appropriate, for site conditions (e.g.,
an arid climate), it may allow you to avoid
constructing an unnecessarily costly WMU design. It
may also provide an additional level of certainty that
liner designs are protective of sites in vulnerable
settings, such as areas with high rainfall and shallow
ground water.
IWEM uses Monte Carlo analysis to handle the
uncertainty associated with default values and other
modeling parameters that are not user-specified. In a
Monte Carlo analysis, a complete simulation (source modeling and fate and transport modeling)
is run thousands of times, sampling input values from distributions for each iteration, to generate
a probability distribution of expected ground water well concentrations for each waste
constituent. For WMUs, well concentrations are calculated for each applicable liner alternative.
IWEM then compares the estimated 90th percentile of the modeled ground water well
concentration to a reference ground water concentration (RGC) value, which is either the
regulatory maximum contaminant level (MCL) or a health-based number (HBN) provided by the
user. For WMUs, it makes this comparison starting with the least effective liner scenario (no
liner) and continuing through the more effective liner scenarios (clay, then composite) until it has
identified the minimum liner design for which the 90th percentile of the estimated ground water
concentration does not exceed the selected RGC for constituents considered.
For structural fills, the IWEM software calculates a distribution of expected ground water well
concentrations for each teachable constituent present in the industrial material used in the
structural fill. For each constituent, IWEM chooses a 90th percentile estimated exposure
concentration for comparison to a benchmark selected by the user. Based on the result of the
comparison, IWEM produces a recommendation on the appropriateness of using the industrial
material in a structural fill. It is recommended that the user consults with the appropriate agency
to ensure that the recommendation comply with state regulations.
In a similar manner, for roadways, which can include multiple structural components, IWEM
calculates distributions of expected ground water well concentrations for all teachable
constituents present in the reused industrial materials for each roadway strip containing teachable
constituent mass. For each constituent, IWEM then sums the 90th percentiles of these
distributions across all strips leaching that constituent to obtain the aggregate 90th percentile
ground water exposure concentration for comparison to the benchmark for that constituent.
Based on the result of the comparison, IWEM produces a recommendation on the
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IWEM User's Guide IWEM Overview
appropriateness of using the industrial material in roadways. It is recommended that the user
consults with the appropriate agency to ensure that the recommendation comply with state
regulations.
IWEM is designed to allow varying levels of site-specific information and data, depending on
what information you have available. IWEM allows you to provide site-specific values for the
most important modeling parameters, but if you have limited site data available, IWEM will use
default values or distributions for parameters for which you have no data. IWEM will also assist
you in making the most appropriate use of the information you do have. For instance, if you know
that a site has an alluvial aquifer, but you do not have site-specific values for ground water
parameters such as hydraulic conductivity, IWEM will assign representative values for alluvial
aquifers from its extensive built-in database of ground water modeling parameters.
IWEM contains a database with chemical properties and MCLs for more than 200 waste
constituents (see Appendix A for a complete list of the constituents). You can also add waste
constituents or modify constituent properties such as soil-water partition coefficient (Kd) or
degradation coefficients in the database. You can also specify user-defined RGCs and the
associated exposure durations.
2.1.2 Detailed Site Assessment
If an IWEM evaluation does not adequately simulate conditions at a proposed site because the
hydrogeology of the site is complex, i.e., the hydrogeologic conditions violate the assumptions
fundamental to the formulation of the ground water pathway model supporting IWEM (See
Sections 3.0 and 4.0 the EPACMTP Technical Background Document, U.S. EPA, 2003a) or
the assumptions and limitations of the IWEM software (see Section 4.3 of the IWEM Technical
Background Document, U.S. EPA, 2015a), you should consider conducting a comprehensive
site- specific analysis. For example, if ground water flow is subject to seasonal variations,
performing an IWEM evaluation may not be appropriate, because the IWEM model is based on
steady-state flow conditions. Likewise, a highly heterogeneous, fractured, or tightly confined
aquifer would not be appropriately represented by IWEM. A comprehensive site-specific ground
water fate and transport analysis may be required to evaluate risk to ground water and alternative
WMU liner designs or structural fill or roadway designs. This type of analysis is beyond the
scope of IWEM. If appropriate, consult with your state agency and use a qualified professional,
experienced in ground water modeling. EPA recommends that you talk to state officials and/or
appropriate trade associations to solicit recommendations for a good consultant to perform the
analysis.
It is important to use a qualified professional because:
• Fate and transport modeling can be very complex; appropriate training and experience are
required to correctly use and interpret models.
• Incorrect fate and transport modeling can result in a liner system that is not sufficiently
protective, or an inappropriate use of industrial materials in a roadway or structural fill.
To avoid incorrect analyses, check to see if the professional has sufficient training and experience
in analyzing ground water flow and contaminant fate and transport.
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IWEM User's Guide IWEM Overview
2.2 IWEM Software Components
IWEM consists of the following main components (or modules):
• Graphical User Interface, which guides you through a series of user-friendly screens to
perform an evaluation;
• Source Term Modules that simulate releases from WMUs, roadways, and structural fills;
• Fate and Transport Model: EPA's Composite Model for Leachate Migration with
Transformation Products (EPACMTP) is the computational engine with integrated Monte
Carlo processor and ground water fate and transport simulator (U.S. EPA, 2003a,b,c,d);
and
• A series of databases of waste constituents and site-specific parameters.
Each of these components is discussed briefly in this section.
2.2.1 IWEM Graphical User Interface
When you use IWEM, you are interacting with the graphical user interface module. This module
consists of a series of data input and display screens, that enable you to define an IWEM
evaluation; view and select parameter input values from IWEM's built-in database; enter your
own site-specific data; and view the results of the IWEM evaluation. Figure 2-1 shows a sample
IWEM user interface screen. A detailed description of each IWEM user interface screen is
provided in Section 3 of this document.
The graphical user interface will take you through a step-wise process of assembling the pertinent
site-specific data. The graphical user interface module also includes options to view and modify
constituent-specific data, as well as add additional constituents to IWEM's constituent database.
Once IWEM has gathered all your data, it will then run the source and fate and transport models.
Upon completion of the site-specific fate and transport simulations, IWEM will display a liner
recommendation for WMUs or, for roadways and structural fills, whether the use of industrial
material for beneficial use is appropriate with respect to the exposure standard you chose. It will
also generate a printed report if desired.
2.2.2 Source Release Modules
2.2.2.1 WMU Release Modules
Releases from WMUs in IWEM are modeled using EPACMTP, which is a sophisticated model
that simulates the release of waste constituents in leachate from land disposal units (as well as
migration through soil and ground water; those fate and transport aspects of EPACMTP are
described in Section 2.2.3).
The source of constituents is industrial waste managed in a WMU located at or near the ground
surface overlying an unconfmed aquifer. Waste constituents leach from the base of the WMU
into the underlying soil. Leachate generation is driven by the infiltration of precipitation that has
percolated through the WMU into the soil. The type of liner at the base of the WMU affects the
rate of infiltration that can occur and, hence, the release of leachate into the soil. EPACMTP also
simulates the ground water mounding that may occur underneath a WMU with a high infiltration
rate and its effect on ground water flow. This may be significant, particularly in the case of
unlined surface impoundments. In cases of very high infiltration rates in settings with shallow
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IWEMUser's Guide
IWEM Overview
ground water, EPACMTP may cap the infiltration rate to avoid having the modeled ground water
mound rise above the bottom of the WMU.
13 Input
Reference GW Cone. (12)
Input Summary (13)
Constituent Properties
Constituent Name
Leach ate
Concentration
(mg/L)
Toxicily
Standard
RGC(mg/L)
Log(Koc)
(L/kg)
Ka
(/mal/yr)
Kn (/yr)
Kb
(/mol/yr)
Kd (L/kg)
Overall Decay
Coefficient (/yr)
Arsenic (III)
U IJi :,b
Aniline (benzeneamine)
Area (m"2):
Distance to well (m): 50
Depth to water fable (m):
Soil type: SILT LOAM
Infiltration:
No Liner: .3256
Single Liner N/A
Composite Liner: N/A
Recharge Rate: 0.3256
40-16 85
(not specified)
Aquiferthickness (m)
Regional hydraulic gradient:
Aguifer hydraulic conductivity (m/yr):
Ground-water pH value (metals only):
Distance to well (m):
(not specified)
(not specified)
(not specified)
(not specified)
50
« Previous
Ne»J»
Figure 2-1. Sample screen from the IWEM graphical user interface.
2.2.2.2 Structural Fill Release Module
Releases from structural fills are modeled using EPACMTP as described in Section 2.2.2.1. The
fill is configured as an unlined landfill with a user-specified fraction of teachable fill materials.
2.2.2.3 Roadway Release Module
The roadway source module in IWEM is a stand-alone component that determines the pattern of
leachate releases from reused industrial materials incorporated into a roadway structure. The
output from the roadway source module consists of a time series of leachate fluxes and
concentrations for each constituent identified in the reused material. If there are multiple, distinct
components in roadway, each containing reused materials, leachate fluxes and concentrations
will be generated for each component. The output is presented to EPACMTP, which uses the
leaching information to conduct fate and transport simulations as it would for a WMU. If there is
a single roadway component that generates leachate, then one Monte Carlo simulation is
conducted for each constituent identified in the leachate. If multiple leaching components are
defined, then EPACMTP will be executed for each constituent present in the leachate of each
component. IWEM then sums the 90th percentiles of the resulting distributions across all
roadway components leaching that constituent to obtain the aggregate 90th percentile ground
water exposure concentration, which is used to determine if the ground water impacts are below
or exceed the user-supplied benchmark.
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Regional Flow Direction
Figure 2-2 depicts a typical roadway
with a segment constructed with
byproduct materials. For the purposes
of model simplicity, that segment is
assumed to be nearly linear and thus
can be approximated by the straight
line segment AB. If the segment to be
modeled is long and meandering, it
must be subdivided into several nearly
linear segments that can each be
represented by a straight line.
Figure 2-3 shows a typical cross
section of a roadway, that may
comprise several components (e.g.,
travel lane, shoulder, ditch). For the
model, each component was idealized
as a column, referred to henceforth as
the roadway-source column. In the
vertical direction, as shown in Figure
2-4, each roadway-source column
included materials starting vertically
upward from a reference datum (which
could be the top of subgrade), to the
surface of a pavement or a road
shoulder or an embankment or a ditch.
As shown in Figure 2-4, each roadway-source column was underlain by a corresponding vadose-
zone column.
Receptor
Well
Highway Segment of Interest
____ Linear Approximation of Highway
Segment of Interest
Figure 2-2. A typical roadway with a recycled-material
segment.
Traveled Lanes
Traveled Lanes
Ditch
Embank-
ment
Gutter Drain subgrade
Permeable
Base
Drain
Ditch
Gutter
Figure 2-3. Atypical cross section of a roadway.
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IWEM Overview
Source Strip i = 1 Source Strip i = 2 Source Strip i =3 Source
Ditch & Left Shoulder Left Lane Right Lane Right
^
sx
7
Vadose Zone 1
n
i
^
Vadose Zone 2
•^
xx
7
Vadose Zone 3
^
Strip i = 4
Shoulder
sx
V
Vadose Zone 4
Figure 2-4. Modules of IWEM corresponding to multiple roadway-source strips.
A roadway-source column was assumed to be uniform in terms of parameters and properties
along the length of interest (i.e., the modeled segment shown in Figure 2-2). Therefore, a
roadway-source column becomes a road way-source strip in three dimensions. Figure 2-5 shows
an example of a roadway cross section comprising three roadway-source strips representing,
respectively, a median, a travel lane, and a ditch.
Median
Travel Lane
Road Shoulder,
'Embankment, and Ditch
^
f
\
/
\
,
/
:;jw&r$s
Layer 2
Layer 1
, ws ,,
Pavement Layer 4
Base ; Layers
Subbase Layer?
Subgrade LayeM
- W2
1
Layer 1
w<
Source Strip 3
Source Strip 2
Source Strip 1
Figure 2-5. An example of layering in roadway-source strips.
Note that a more typical roadway may consist of up to 15 roadway-source strips: for example,
left shoulder, left-travel lane, median, right-travel lane, and right shoulder in Figure 2-4. More
strips are possible to account for drainage ditches and berms and different configurations of
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IWEM User's Guide IWEM Overview
layers; the IWEM roadway module limits the total number of roadway-source strips to 15. An
example of only three roadway-source strips is used here as a basis for further discussion. Each
roadway-source strip may consist of several layers, depending on how a given roadway was
constructed. A travel lane strip may be composed of a pavement layer (portland cement concrete
or asphalt concrete), a base-course layer, a subbase layer, and a subgrade layer. A median may
comprise a base layer, a subbase layer, and a subgrade layer. An unpaved road shoulder may have
only one layer—a subgrade layer. With this type of conceptualization, one can easily see that
each roadway-source strip was equivalent to the existing landfill source module that is available
within EPACMTP. However, the landfill module in IWEM can accommodate only sources with
a square footprint and one layer.
As shown Figure 2-2, the ground water flow direction is not perpendicular to the segment of
interest. The roadway module can accommodate a scenario where the ground water flow
direction is not perpendicular to the axis of the roadway. In addition, the location of the ground
water well is not restricted. These two features are unique to the roadway module. IWEM input
screens will help you define the location of the ground water well and the direction of ground
water flow.
2.2.3 EPACMTP Fate and Transport Model
IWEM uses EPACMTP to model the subsurface fate and transport of contaminants. EPACMTP
is a sophisticated fate and transport model that simulates the migration of waste constituents in
leachate from land disposal units or beneficial application sites through soil and ground water.
EPACMTP was developed by EPA's Office of Resource Conservation and Recovery (ORCR) to
support risk-based ground water assessments under RCRA. EPACMTP has been applied to waste
identification, hazardous waste listing and other regulatory evaluations. This User's Guide
provides only a brief summary of EPACMTP; a complete description of the model is provided in
the EPACMTP Technical Background Document (U.S. EPA, 2003a). The IWEM Technical
Background Document (U.S. EPA,2015a)is provided with IWEM as a companion to this User's
Guide and describes how IWEM uses EPACMTP.
EPACMTP simulates fate and transport of constituents in both the unsaturated zone and the
saturated zone. Figure 2-6 shows a conceptual, cross-sectional view of fate and transport
modeled by EPACMTP. The source of constituents in the figure is a WMU located at or near the
ground surface overlying an unconfmed aquifer, but could also be a roadway or structural fill.
Waste constituents leach from the base of the source into the underlying soil. They migrate
vertically downward until they reach the water table. As the leachate enters the saturated zone, it
will mix with ambient ground water (which is assumed to be free of pollutants) and a ground
water plume will develop that extends in the direction of downgradient ground water flow.
Although it is not shown in Figure 2-6, EPACMTP accounts for the spreading of the plume in all
three dimensions.
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IWEM Overview
LEACHATE CONCENTRATION
UNSATURATED
ZONE
WASTE MANAGEMENT UNIT OR ROADWAY
WELL
I LEACHATE
LAND SURFACE
WATER TABLE
SATURATED
ZONE
LEACHATE PLUME
Figure 2-6. Conceptual view of aquifer system modeled by EPACMTP.
Leachate generation is driven by the infiltration of precipitation that has percolated through the
source into the soil. The type of liner at the base of the WMU affects the rate of infiltration that
can occur and, hence, the release of leachate into the soil. Likewise, surface or internal materials
used in a roadway or structural fill can affect the infiltration rate through the structure.
EPACMTP models flow in the unsaturated zone and in the saturated zone as steady- state
processes, that is, it models long-term average flow conditions. EPACMTP also simulates the
ground water mounding that may occur underneath a source with a high infiltration rate and its
effect on ground water flow. This may be significant, particularly in the case of unlined surface
impoundments. In cases of very high infiltration rates in settings with shallow ground water,
EPACMTP may cap the infiltration rate to avoid having the modeled ground water mound rise
above the bottom of a source.
EPACMTP accounts for the dilution of the constituent concentration caused by the mixing of the
leachate with ground water. EPACMTP also accounts for attenuation due to sorption of waste
constituents in the leachate onto soil and aquifer solids, as well as bio-chemical transformation
(degradation) processes in the unsaturated and saturated zone. These processes reduce constituent
concentrations in the ground water as a function of time.
Sorption refers to the process whereby constituents in the leachate attach themselves to soil
particles. For organic constituents, EPACMTP models sorption between the constituents and the
organic matter in the soil or aquifer, based on constituent-specific organic carbon partition
coefficients (Koc) and a site-specific organic carbon fraction in the soil and aquifer. For metal
constituents, EPACMTP accounts for more complex geochemical reactions by using effective
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IWEM User's Guide IWEM Overview
sorption isotherms for a range of aquifer geochemical conditions, as generated using the
MESTTEQA23 geochemical speciation model.
By default, EPACMTP only accounts for constituent transformations caused by hydrolysis
reactions. Hydrolysis refers to constituent decomposition that results from chemical reactions
with water. However, you may also enter site-specific biodegradation rates. Biodegradation refers
to constituent decomposition reactions involving bacteria and other micro-organisms. EPACMTP
simulates all transformation processes as first-order reactions, that is, as processes that can be
characterized with a half-life.
EPACMTP accounts for constituents that hydrolyze into toxic daughter products. In that case, the
final IWEM results account for both the parent constituent and any toxic daughter products. For
instance, if a parent waste constituent rapidly hydrolyzes into a persistent daughter product, the
ground water exposure caused by the parent itself may be minimal (it has already degraded before
it reaches the well), but the results would be based on the exposure caused by the daughter
product.
For WMUs, IWEM makes liner recommendations by comparing ground water exposure
concentration values estimated by EPACMTP against RGCs that are either regulatory MCLs or
user-supplied benchmarks. For roadways and structural fills, IWEM makes the same comparison
to determine if the beneficial reuse of industrial material in the design is appropriate (estimated
ground water exposure concentration is less than the selected benchmark) or not. For an IWEM
analysis, the ground water exposure concentration is evaluated at a hypothetical well located
downgradient from the source. EPACMTP accounts for the finite life- span of WMUs, which
results in a time-dependent ground water exposure concentration. The exposure concentration
calculated by EPACMTP is the maximum average concentration during the time period in which
the ground water exposure at the well occurs. The length of the exposure averaging period is
adjusted to match exposure duration specified by the user. For instance, if the supplied
benchmark assumes a 30-year exposure duration, the averaging period for calculating the average
ground water exposure concentration is set to 30 years.
2.2.3.1 IWEM vs. EPACMTP
As an IWEM user, you should understand the differences between IWEM and EPACMTP.
EPACMTP is a full-featured ground water flow and transport model with probabilistic modeling
capabilities; it is a sophisticated software program which requires a significant amount of
computer and ground water modeling expertise to create the necessary input files, execute the
model, and interpret the results.
In contrast, IWEM is a relatively simple and user-friendly program created specifically to conduct
screening analyses of the ground water. Specifically, IWEM converts your input values into the
required EPACMTP input files, executes a series of EPACMTP modeling runs, and then
compiles and analyzes the results to produce a finding that is specific to your waste and your
waste site or beneficial use. In addition, IWEM can print and save document-ready reports that
include the results of an IWEM evaluation and the input data on which they are based.
3 MINTEQA2 (U.S. EPA, 1991) is a geochemical equilibrium speciation model for computing equilibria among
the dissolved, absorbed, solid, and gas phases in dilute aqueous solution.
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IWEM User's Guide IWEM Overview
In summary, IWEM can be thought of as an application of EPACMTP that is tailored specifically
for use in non-hazardous industrial waste management decision- making. In order to make IWEM
appropriate and easy to use in performing these analyses, not all of the EPACMTP functionality
is available in IWEM; however, IWEM provides added capabilities to interpret results and
develop reports, which are not available in EPACMTP.
2.2.4 IWEM Databases
The final component of IWEM is an integrated set of databases that include waste constituent
properties and other ground water modeling parameters. The waste constituent database includes
206 organic chemicals and 22 metals (25 for the Roadway Module). Appendix A provides a list
of the constituents in the database. The constituent properties include physical and chemical data
needed for ground water transport modeling, and regulatory MCLs
In addition to constituent data, IWEM includes a comprehensive database of ground water
modeling data, including infiltration rates for different WMU types, liner designs, roadway
materials, and structural fills for a range of locations and climatic conditions throughout the
United States; and soil and hydrogeological data for different soil types and aquifer conditions
across the United States. Details of these databases are provided in the EPACMTP
Parameters/Data Background Document (U.S. EPA, 2003b,d) and in the IWEM Technical
Background Document (U.S. EPA, 2015a).
IWEM uses these databases to perform evaluations. When site-specific data are available for an
IWEM evaluation, they will override default database values. Conversely, when site-specific data
are not available for an IWEM evaluation, IWEM will use default values or random sampling of
values from distributions in its databases to augment the user-provided data.
2.3 Assumptions and Limitations of Ground Water Modeling Using IWEM
IWEM uses sophisticated probabilistic techniques to account for uncertainty and parameter
variability. To perform these evaluations, the mathematical models represent conditions that may
potentially be encountered at waste management sites and beneath roadways or structural fills
within the United States. Efforts have been made to obtain representative, nationwide data and
account for the uncertainty in the data.
However, given the complex nature of the evaluations, a number of limitations and caveats must
be delineated. These limitations are described in this section. Since IWEM relies on EPACMTP
to model the source as well as fate and transport through the unsaturated and saturated zone, the
discussion focuses on the limitations and assumptions inherent to EPACMTP. Before using this
software, you need to verify that the model assumptions are appropriate for the site you are
evaluating. The IWEM Technical Background Document (U.S. EPA, 2015a) provides additional
information to assist you in this process.
EPACMTP represents WMUs, roadways, and structural fills in terms of a source area and a
defined rate and duration of leaching. EPACMTP only accounts for the release of leachate
through the base of the source and assumes that the only mechanism of constituent release is
through dissolution of waste constituents in the water that percolates through the source.
EPACMTP does not account for the presence of non-aqueous free-phase liquids, such as an oily
phase that might provide an additional release mechanism into the subsurface. EPACMTP does
not account for releases from the source via other environmental pathways, such volatilization or
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IWEM User's Guide IWEM Overview
surface run-off. EPACMTP assumes that the rate of infiltration through the source is constant,
representing long-term average conditions; the model does not account for fluctuations in rainfall
rate, or degradation of liner systems that may cause the rate of infiltration and release of leachate
to vary over time.
EPACMTP does not explicitly account for the presence of macro-pores, fractures, solution
features, faults or other heterogeneities in the soil or aquifer that may provide pathways for rapid
movement of constituents. A certain amount of heterogeneity always exists at actual sites, and it
is not uncommon in ground water modeling to use average parameter values. This means that the
input values for parameters such as hydraulic conductivity, dispersivity, etc. represent effective
site-wide average values. However, EPACMTP may not be appropriate for sites overlying
fractured or very heterogeneous aquifers.
EPACMTP is designed for relatively simple ground water flow systems. EPACMTP treats flow
in the unsaturated zone and saturated zone as steady state and does not account for fluctuations in
the infiltration or recharge rate, either in time or areally. As a result, the use of EPACMTP may
not be appropriate at sites with large seasonal fluctuations in rainfall conditions, or at sites where
the recharge rate varies locally. Examples of the latter include the presence of surface water
bodies such as rivers and lakes or ponds, and/or man-made recharge sources near the WMU.
EPACMTP does not account for the presence of ground water sources or sinks such as pumping
or injection wells.
Leachate constituents can be subject to complex biological and geochemical interactions in soil
and ground water. EPACMTP treats these interactions as equilibrium sorption and first-order
degradation processes. In the case of sorption processes, the equilibrium assumption means that
the sorption process occurs instantaneously, or at least very quickly relative to the time-scale of
constituent transport. Although sorption, or the attachment of leachate constituents to solid soil
or aquifer particles, may result from multiple chemical processes, EPACMTP lumps these
processes together into an effective soil-water partition coefficient. In the case of metals,
EPACMTP allows the partition coefficient to vary as a function of a number of primary
geochemical parameters, including pH, leachate organic matter, soil organic matter, and the
fraction of iron-oxide in the soil or aquifer.
Although EPACMTP is able to account for the most important ways that the geochemical
environment at a site affects the mobility of metals, the model assumes that the geochemical
environment at a site is constant and is not affected by the presence of the leachate plume. In
reality, the presence of a leachate plume may alter the ambient geochemical environment.
EPACMTP does not account for colloidal transport or other forms of facilitated transport. For
metals and other constituents that tend to strongly sorb to soil particles, and which EPACMTP
will simulate as relatively immobile, movement as colloidal particles can be a significant
transport mechanism. However given sufficient site-specific data, it is possible to approximate
the effect of these transport processes by using a lower value for the Kd as a user-input.
EPA's ground water modeling database includes constituent-specific hydrolysis rate coefficients
for constituents that are subject to hydrolysis transformation reactions; for these constituents,
EPACMTP simulates transformation reactions subject to site- specific values of pH and soil and
ground water temperature, but other types of transformation processes are not explicitly simulated
in EPACMTP. For many organic constituents, biodegradation can be an important fate
mechanism, but EPACMTP has only limited ability to account for this process. The user must
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IWEM User's Guide IWEM Overview
provide an appropriate value for the effective first-order degradation rate. In the IWEM
application of EPACMTP, the model uses the same degradation rate coefficient for the
unsaturated and saturated zones if this parameter is provided as a user-input. In an actual leachate
plume, biodegradation rates may be different in different regions in the plume; for instance in
portions of the plume that are anaerobic some constituents may biodegrade more readily, while
other constituents will biodegrade only in the aerobic fringe of the plume. EPACMTP does not
account for these or other processes that may cause a constituent's rate of transformation to vary
in space and time.
Three of the four WMUs in IWEM and EPACMTP are considered temporary and their leaching
durations are determined by the user-supplied value for operational life. Although these WMUs
might be described as temporary, default values for their operational lives range from 20 to 50
years. EPACMTP was designed and fine-tuned to efficiently determine peak and average ground
water concentrations at a well assuming that leaching durations would be long enough to capture
the changing ground water concentrations in terms of years rather than days. Unless EPACMTP
is appropriately modified, EPACMTP is not able to accurately capture peak concentrations at
receptor wells for extremely short leaching durations of 1 year or less. A minimum value for
operational life should be at least 5 to 10 years to ensure that EPACMTP accurately identifies a
peak or average ground water concentration at the well.
IWEM allows the user to specify many key input parameters like the location of the ground water
well where exposure concentrations are evaluated. Given the nature of these sensitive
parameters, seemingly conservative choices can generate non-intuitive results that may lead the
user to question the rigor of the model. It is very important, therefore, to be careful in selecting
values for your inputs and understand how the remaining input parameters are related and how
they are selected.
For example, in IWEM a user can specify where a ground water well is placed down-gradient of
the source area but has no control over the depth of the well below the water table. The default
depth of the ground water well in IWEM varies uniformly between 0 and 10 m or the thickness
of the saturated zone, whichever is less. Consider a scenario where the well is placed very close
to the source area. In Figure 2-6, the region of the saturated zone contaminated by leachate
expands as the distance from the source increases. Very close to the source, the plume is
relatively shallow and deepens at the distance from the source increases. There is reasonable
likelihood that a random depth for a well very close to the source might actually be below the
plume extent. Now, imagine that the source is small or very narrow (like a roadway). The plume
depth is even shallower. The likelihood of the well missing the plume increases. This
phenomenon could very well bias the estimated ground water exposure concentration to be
lower, much lower than expected, causing the user to question the results of the analysis.
Therefore, for such types of scenarios, IWEM is not an appropriate tool and the user should
consider using a more site-specific analysis. More information on the limitations of IWEM on the
down-gradient well distance is presented in Section 6.1.3 of the IWEM Technical Background
Document (U.S. EPA, 2015a).
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IWEMUser's Guide
Running the IWEM Software
3. Running the IWEM Software
This section provides detailed instructions on how to run the IWEM software. Specifically, this
section:
• Instructs you how to launch the IWEM software;
• Explains the key features of the IWEM software; and
• Guides you step-by-step through IWEM evaluations.
3.1 How Do I Start the IWEM Software?
To use the program for the first time, download it from EPA's website (http://www.epa.gov/
osw/nonhaz/industrial/tools/iwem/) to your hard-drive and install it. Section 1.2.2 gives detailed
installation instructions.
The installation package will place an icon on your desktop unless you specify not to.
You can launch IWEM by double-clicking the IWEM icon (shown at right) on your ~tf
desktop. If you opt not to let the installation package place an icon on your desktop, you
can launch the program by choosing |START|PROGRAMS| (at the lower left corner of the screen) and
then choosing the |IWEM| program group and the program |IWEM|.
3.2 What Are the Key Features of the IWEM Software?
3.2.1 General User Interface Features
The IWEM software has a user-friendly interface that is designed to operate in accordance with
Microsoft Windows conventions. The first screen that appears after launching the program is the
Start-Up screen (shown below), which will appear only while the program is loading.
.
. ^^ *
Industrial Waste Management
Evaluation Model
IWEM
U.S. Environmental
Protection Agency Office
of Resource
Conservation and
Recovery
Version 3.1
Initializing...
The first time you run the IWEM software, it will display five Introductory screens. After reading
them once, you can skip these screens in the future by editing the setting for Intro Screens under
Options in the Menu Bar.
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The IWEM software interface follows a common layout with the following features, as presented
in Figure 3-1:
• Menu Bar allows you to perform common file operations;
• Toolbar allows you to perform common operations efficiently;
• Title Bar at the top displays the software title and the name of the current IWEM project
file;
• Screen Name identifies the type of information being requested or displayed in the
screen;
• |PREVious| button takes you to the previous screen; and
• |NEXT| button allows you to proceed to the next screen.
sktop\IWEM \Examples\LF_example.wem]
13 Input
Constituent List (1 0)
Constituent Properties (11) Reference GW Cone (12) j v Input Summary (13)
Constituent Properties
>
Related
Constituents
CAS
22569-72-8
62-53-3
Constituent Name
Arsenic (111)
Aniline (benzeneamine)
Leachats Toxidty RGC(mg/L) Log(Koc) Ka Kn (/yr) Kb Kd (L/kg) Overall Decay
Concentration Standard (L/kg) (/mol/yr) (/mol/yr) Coefficient (/yr)
(mg/L)
0.0156 MCL 0.01
00045 HBN- 0.0169 O.S95 O.OOE.OO O.OOE.OD O.OOE.OO
4rea(m"2):
Depth of base of the LF below ground surface (rn):
WMU depth (m) [requires site specific value]:
Depth to watertable (m):
Soil type: UNKNOWN SQILTYPE
Infiltration:
No Liner: Monte Carlo
Single Liner1 Monte Carlo
Composite Liner: Monte Carlo
Recharge Rate: Monte Carlo
1000
2
(not specified)
Aquifer thickness (rn).
Regional hydraulic gradient1
Aquifer hydraulic conductivity (m/yr):
Ground-wafer pH value (metals only).
Disfance to well (m):
(not specified)
(not specified)
(not specified)
(not specified)
50
Go to next
Next»
Figure 3-1. General IWEM screen features.
From the menu bar, you can select among the following menu items:
• File: Performs general file operations, such as open and save;
• Options: Enables or suppresses toolbar and introductory screen visibility; and
• Help: Provides access to the following information: search IWEM online help; view
IWEM Introductory screens; browse constituent properties; browse terminology
definitions; view contact information for IWEM technical support; and view the IWEM
About screen.
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IWEM User's Guide Running the IWEM Software
Using the toolbar is a quick way to perform common operations, such as the following:
| _J Clicking on this button begins a new evaluation;
Clicking on this button launches the |OPEN FILE| dialog box to select the
previously saved evaluation file to be opened;
Clicking on this button launches either the |SAVE As| or |SAVE| dialog box so
that you can specify the filename and folder for your analysis;
Clicking on this button opens the |CoNSTiTUENT PROPERTIES BROWSER! dialog box.
If you are unsure about the function of any of the toolbar buttons, you can display Tool Tips
(which identifies the button's function) for each button by placing the mouse cursor on top of the
button.
This section of the User's Guide presents detailed, step-by-step instructions for running the
IWEM software. These instructions include screenshots for each of the screens and dialog boxes
that you will see when performing an analysis in IWEM. The screenshots presented in this
section have added annotations (in small boxes above and below the screenshot) to point out the
important features on each screen. These annotations are each labeled with a letter (e.g., A, B, C)
and are then listed and explained sequentially in the bulleted text immediately following each
screenshot.
3.2.2 What is the Constituent Properties Browser?
The Constituent Properties Browser, accessed from the Main Menu sequence |HELP| CONSTITUENT
PROPERTIES! or by clicking on the flask toolbar button, displays the data in the constituent
properties database that is distributed with IWEM (see Figure 3-2). You can select a constituent
by Chemical Abstract Service Registry number (CAS number) or by name. The information
displayed in the upper portion of the browser includes chemical and physical properties required
for fate and transport modeling.
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IWEMUser's Guide
Running the IWEM Software
^
Constituent Properties Browser
Select a constituent by CAS number or name.
CAS Number:
r Physical Properties -
Parameter
Constituent type
Carcinogen?
Molecular weight (g/mol)
Log KOC (distribution coefficient tor organic carbon)
Ka: acid-catalyzed hydrolysis rate constant (1/yr)
Kn; neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/yr)
Solubility (mg/L)
Diffusivity in air(cm"2/s)
Dittusivity in water (mA2/yr)
Henrys law constant (atm-m"'3/mor)
N/A
N/A
N/A
N/A
CambridgeSoft Corporation, £001
To view a full citation, click in the
Reference cell, then click the "Extended
Rpfprpm-p" hnttnn
QK
Figure 3-2. Constituent Properties Browser.
The features identified in Figure 3-2 are explained in more detail in the following paragraphs.
A. Choose Constituent to View by Selecting CAS Number. To select which constituent to
view, use either of the two list boxes at the top of the screen. You can click on the drop-
down list control (vl) at the right edge of the |CAS NUMBER| list box to display a drop-down
list of all available waste constituents. Then, use the mouse or the |ARROW| keys on your
keyboard to scroll through the list of constituents until the desired constituent is
highlighted. You can also type in the leading digits of the CAS number for the constituent
you would like to view. IWEM will then skip forward in the list to the first constituent
whose CAS number starts with the entered digits, and you can then use the mouse or the
|ARROW| keys on your keyboard to move to the desired constituent. Left click on the mouse
or hit the |El\lTER| key to make your selection.
B. Choose Constituent to View by Selecting Name. You can also select which constituent
to view by using the |CONSTITUENT NAME| list box on the right side of the screen. Click on the
drop-down list control (^) at the right edge of the |CONSTITUENT NAME| list box to display a
drop-down list of all available waste constituents. Then, use the mouse or the |ARROW| keys
on the keyboard to scroll through the list of constituents until the desired constituent is
highlighted. You can also type in the first letter of the name of the constituent that you
would like to view. IWEM will then skip forward in the list to the first constituent whose
name begins with the entered letter, and you can then use the mouse or the |ARROW| keys
on your keyboard to move to the desired constituent. Left click on the mouse or hit the
|El\lTER| key to make your selection.
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IWEM User's Guide Running the IWEM Software
C. Physical Properties. For the selected waste constituent, the pertinent physical and
chemical property values that are used in the IWEM analysis and their corresponding data
sources are listed in the upper window on this screen.
D. Physical Properties Abbreviated Reference. Abbreviated references are listed for each
value.
E. Reference Ground Water Concentrations. For the selected waste constituent, any MCL
values in the IWEM database are listed in the lower table on this screen. User-entered
Reference Ground Water Concentration (RGCs), such as health-based numbers (FtBNs)
and other user-defined RGCs are not displayed in the Constituent Properties Browser, but
may be viewed and edited on the Reference Ground Water Concentration input tab.
F. Reference Ground Water Concentration Abbreviated Reference. Abbreviated
references are listed for each value.
G. Click to Extended Reference for Selected Property. You can view the complete
bibliographic citation of a constituent property (except constituent type, carcinogenicity,
and molecular weight) by selecting the corresponding entry in the Reference column of
one of the tables and clicking on the [EXTENDED REFERENCE! button on the lower right-hand
side of the screen. Doing so will cause a message box to appear on-screen containing a
complete bibliographic citation.
H. Close Constituent Properties Browser. Click the |OK| button at the bottom of the screen
to close this screen.
3.2.3 How Do I Navigate Through the IWEM Software?
The IWEM software consists of a series of screens containing controls for entering data and
viewing results. This section describes in detail how to move from screen to screen and control to
control, as well as how the various controls are used together to facilitate the use of the IWEM
software. Although this guide assumes you will be using a mouse to navigate through the screens
and features, you may also navigate using the keyboard exclusively.
Navigating with the keyboard involves the use of the following keys: the |TAB| key, the |BACK-TAB|
key, the |ARROW| keys, the |Al_T| key, and the |ENTER| key. The |TAB| key moves the cursor from one
control to the next in a predefined order. The term cursor refers to either a vertical bar " " that
indicates the position of the next typed character, or the change in a control's appearance from
normal to a highlighted appearance, as shown here:
OK I XT 1
-'.1. 1 Normal
OK l
^fypy^l Highlighted (note the dotted line just inside the perimeter of the button).
When a control is highlighted, it is considered actively awaiting input from the keyboard or
mouse. The |BACK-TAB| key (obtained by pressing the |TAB| key while holding down the |SHIFT| key)
moves the cursor in the reverse order. When the cursor is on a command button, press the |ENTER|
key to "click" the button. Radio buttons always appear in a set of two or more options; when the
cursor is on any radio button, press the |ARROW-UP| or |ARROW-DOWN| key to select a different radio
button. The |TAB| key moves you off the radio button group. The |TAB|, |BACK-TAB|, and |ARROW| keys
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IWEM User's Guide Running the IWEM Software
are also used to move from cell to cell in a data grid. A drop-down list displays the current choice
of several possible choices; when the drop-down list is active (highlighted), use the |ARROW-UP| or
|ARROW-DOWN| keys to display the desired choice.
The |ALT| key is used in combination with other key strokes to access controls or menu items
quickly through pre-defined "hot-keys" that correspond to underlined characters on a control or
menu item. For example, the underlined "O" on the |OK| button above indicates that pressing and
holding down the |Ai_T| key and then pressing the |0| key would have the same result as a mouse
click on the button. Similarly, the main menu system is activated by pressing the |ALT| key; the
first letter of each menu item is underlined and can be accessed in the manner just described.
3.2.3.1 Screens
The software is set up as a series of screens through which you can navigate to enter data and
view results.
You can move through the program using three different methods:
• Clicking on one of the toolbar buttons, or clicking on the Evaluation menu,
• Clicking on the |NEXT| or |PREVious| buttons at the bottom of the screen, or
• Clicking on one of the labeled tabs located at the top of the data entry and results screens
(navigation among the tabbed screens is only allowed for those screens that are active).
Screens in IWEM appear as a single screen or as a group of screens with manila folder-like
"tabs" along the top to differentiate between the individual screens. The Introductory screens are
examples of individual screens that have |PREVious| and/or |NEXT command buttons along the
bottom for navigating from screen to screen. The input screens consist of seven screens where
you select a source or WMU type, identify the constituents in your waste, enter your leachate
data, and specify the geometry and layout of the roadway, as well as other site-specific
information. In addition to the navigational command buttons available on single screens, you
can also move to adjacent screens by clicking on their corresponding tab.
3.2.3.2 Controls
Various types of controls make the IWEM software easy to use. Examples of each of these
controls from several IWEM screens are shown in Figure 3-3 and explained in more detail in
this section. The letters in the figure correspond to the lettered bullets in the text. In general, a
control is activated or selected by clicking on it with the mouse or by using the keyboard (e.g.,
using the |TAB| key to select the next control).
A. Text Boxes. Text boxes are used to display or accept information. In the screen shown in
Figure 3-3, text boxes are used to accept the name or CAS number of a constituent. As
you type characters or numbers into the text box, the list box cursor moves to the
constituent in the list that best matches your input.
B. List Boxes. List boxes are used to display a list from which you can select one or many of
the listed items. In Figure 3-3, the list box displays all of the constituents in the IWEM
database that can be used in an analysis.
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IWEMUser's Guide
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E Input a \ B i-^!
Subsurface Parameters (8) ^T^ft Infillralion (9) Constituent List (1 0) Constituent Properties (1 1 )
VB^|
Constituent Name:! (S Constituent Name (" All constituents
CAS^f- r CAS Number C ^"^ ^fjl
r Metals ••
All Constituents 99JB
83-32-9 Acenaphthene .»
7S-07-0 Acetaldehyde [Ethanol]
67-64-1 Acetone (2-propanone) ^
75-05-8 Acetonitrile (methyl cyanide) «^
98-86-2 Acetophenone ' '
1 07-02-8 Acrolain ^
79-06-1 Aciylarnide "^~
107-13-1 Actylonitrie
303-00-2 Aldrin
107-1 8-6 Allylalcoho
62-63-3 Aniline (benzeneamine)
1 20-1 2-7 Anthracene
74 4 0-36-0 Antimony
22569-72-8 Arsenic (III)
15584-04-0 Arsenic (V)
7410-39-3 Barium
56-55-3 Benz{a}anthracene
71-4 3-2 Benzene
92-87-5 Benzidine
50-32-8 Benzo{a}pyrene
205-99-2 Benzo{b}f!uorenthene
100-51 -6 Benzyl alcohol
100-44-7 Benzyl chloride
7440-41 -7 Beryllium
111-44-4 Bis(2-chloroethyl)ether
« Previous
Selected Constituents
CAS Constituent Name Leachate
Number Concentration
(mg/L)
> 22569-72-8 Arsenic (III) 0.01 56
62-53-3 Aniline (benzenearnine) 0.0045
b\acl utes\Des kto p\IWEM\Exa m ples\Roadway_S cen ario4. wem ]
,
y
^oramete
to repres
3e surroun
•ameters i
.tion:
Add New Constituent
j|uy| 4
i3 Input
Iptittrntinn (
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IWEM User's Guide Running the IWEM Software
C. Radio Buttons. Radio buttons always appear in sets of two or more and are used when
you can only choose one of the options listed. In the figure, you can choose to display all
constituents, organics only, or metals only. If you make a different selection, the old
selection is unselected. Select an option by clicking on it.
D. Data Grids. Data grids are like a spreadsheet within IWEM and are used to display data,
accept data, or a combination of those; they can also contain items you select to affect
other controls on a screen. The grid column widths and row heights can be manipulated
with the mouse by moving the mouse cursor over the separators along the left side or top
of the grid until the cursor changes to a horizontal or vertical bar. When the cursor
changes, click and drag the mouse until you are happy with the new grid dimension, then
release the mouse button. Moving from cell to cell can be controlled by mouse clicks or
by the |TAB| or |ARROW| keys, as explained in Section 3.2.3. Select a particular row of the
grid by clicking on the cell in that row or along the left border of the grid or using the |TAB|
or |ARROW| keys to move to a particular row. In the screen in Figure 3-3, to remove a
constituent from the list displayed in the data grid, select the grid row and then click the
command button with the left-pointing arrow.
E. Command Buttons. Command buttons are used to execute an action, navigate from
screen to screen, verify a choice, or acknowledge a message. Figure 3-3 shows a screen
from IWEM where command buttons are used for various purposes: navigation (the
PREVIOUS! and |NEXT| buttons), moving information (the arrow buttons between the list box
and data grid), and initiating some action (the |ADD NEWCONSTITUENT| button). Command
buttons are activated by a mouse click or by pressing the |ENTER| key when the button is
highlighted or active.
F. Drop-down Lists. Drop-down lists are used to make one selection from a list and then
display only the selected item. In some cases, you may also be able to enter data in a drop
down list—this type of control is usually referred to as "combo" box control: a
combination of a text box control and drop-down box control.
G. Checkboxes. Checkboxes are similar to radio buttons, except you can check more than
one in a set. Checking a checkbox turns on the listed option. Click on the box to check
and uncheck it.
H. Dialog and Message Boxes. Dialog boxes appear throughout IWEM as additional data
entry screens containing one or more of the controls mentioned above or as a way of
informing the user. Data entry dialog boxes usually appear as a direct result of clicking on
a command button, whereas message boxes appear as the result of an input or calculation.
3.2.4 How Do I Save My Work?
You have several options within the IWEM software to save your analysis. After performing a
new analysis, you can click on the |SAVE| button on the Toolbar or choose |FiLE|SAVE| or |FiLE|SAVE As|
from the Menu Bar to launch the standard Windows |SAVE As| dialog box. Using the Windows
|SAVE As| dialog box, you can navigate to any folder location you prefer. The |SAVE As| dialog will
always default to the last location that you saved to. If you open a saved analysis, and then make
changes to it, clicking on the |SAVE| button on the Toolbar or choosing |FlLE|SAVE| from the Menu
Bar will overwrite the contents of your original file with the current analysis settings; if you want
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IWEM User's Guide Running the IWEM Software
to save these changes to a new file, you must choose |FlLE|SAVE As| from the Menu Bar. If you
forget to save before trying to exit IWEM or open a new file, a dialog box will automatically ask
if you want to save your data before exiting the software or opening the new file. You will also
be prompted to save your file after the run is complete to ensure that results are saved.
For each saved analysis, IWEM creates two project files in the location you specified in the
|SAVEAs| dialog box:
• *.wemfile
• *.mdb file.
The combination of these two files completely describes the information you have entered
(*.mdb) and any model-generated results (*.wem). The asterisk (*) is replaced by the name you
assign to the project; the files will be saved in the project folder you specified.
Note that IWEM will not allow you to save both model inputs and results at a point where the
inputs do not correspond to the model-generated results (e.g., when results have been generated,
you return to an input screen, change an input, and attempt to save the project). If you do choose
to save your work in a situation like this, only the inputs will be saved; that is, when you later
open up this file, you will have to run the analysis to create the corresponding results.
You may open a previously saved IWEM analysis by clicking on any one of the following
options:
• |OPEl\l| button on the Toolbar
|FlLE|OPEN| selection from the Menu Bar.
Once the |OPEN| dialog box is displayed, highlight the appropriate file and click the |OPEN| button
to open the desired file. IWEM comes with saved project files that correspond to the example
problems in Appendices B, C, and D. Those files are installed to either
• C:\Users\Public\Documents\IWEM\SampleData or
• C :\Users\[your user name]\Documents\IWEM\SampleData.
Note that IWEM 3.1 includes structural changes to the database that prevents some saved
evaluation data from versions 1.0 and 2.0 of IWEM from being imported (e.g., HBNs were
removed and must now be provided by the user). If IWEM detects that the saved scenario is out-
of-sync with the current IWEM installation, IWEM will notify you with a message saying, "The
version of the evaluation database ([path]) you are opening is different than the IWEM
application database ([path]). Some saved evaluation data, including results, may not be
imported. NOTE: You will have to re-enter any missing data and re-run the evaluation." IWEM
will load what information it can, however, you will need to review the scenario inputs, re-enter
any missing data, and then re-run the evaluation.
You will then see a dialog box in which you can choose to view the input screens or cancel. If the
file contains saved results and you want to view those, select |ViEW INPUT SCREENS! and keep
clicking on |NEXT| at the bottom right; once you get to the Run Manager screen, clicking |NEXT| will
take you to results.
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3.2.5 How Do I Get Help If I Have a Problem or a Question?
This document provides extensive guidance on using IWEM. In addition, IWEM includes a built-
in help feature. If you have technical problems or questions that are not answered by this User's
Guide or the built-in help, or you are having difficulty installing IWEM, contact information is
provided below where you can get additional help.
3.2.5.1 How Do I Use the Built-in Help?
IWEM provides online help that can be accessed from any screen either by pressing the |F1| key
or by selecting |HELP| CONTENTS! from the IWEM menu bar. Selecting |HELP| CONTENTS! from the
IWEM menu bar will display the screen shown in Figure 3-4. The features identified in Figure 3-
5 are explained in more detail in the following paragraphs. The left side of the main Help screen
displays tabbed options for browsing or accessing the content. Details of the content are
displayed on the right-hand side of the window. The content is based on HTML and behaves very
much as a web page does.
§ Help for IWEM 3.0 Beta with Roadway Module
Back Print Options
Contents Index I Search
B IQ IWEM Help
@ About This Help File
H ^ Program Overview
B Ifl Working With IWEM
H ^ Program Components
+
^ Progr
^i BB
H ^ Understanding [WEM Inputs
H ^ Interacting with EPACMTP
B ^ Interpreting IWEM Results
B ^ IWEM Reports
^ Help for Specific Dialogs
Navigating the IWEM Interface
The IWEM Interface Follows a Specific Sequence
Using Command Buttons to Navigate
Using the Tabs to Navigate
Saving Your Analysis
Loading an Existing Analysis
Figure 3-4. IWEM online help.
From this main Help screen, you can use the mouse or keyboard keys to explore the |CONTENTS|
tab, which is automatically displayed by default, or you can navigate to either of the other two
tabs: |!NDEX| and |SEARCH|. On the (CONTENTS) tab, a single click on a book icon or topic will update
the display in the right-hand pane of the screen with more detailed content corresponding to the
selected item. You can also double-click on the book icon to the left of each topic to expand that
topic, and again to collapse the topic; some main topics contain multiple levels of sub-topics.
With every click of the mouse in the left-hand pane, the right-hand pane of the Help screen will
be updated to display the associated content that may explain a particular feature of the IWEM
software or define a term, etc. Much of the content contains hyper-text links to related items in
the online |HELP|; these hyper-text links are formatted with colored and underlined text. A single
click on any hyper-text link automatically displays the related content in the right-hand pane and,
at the same time, navigates and selects the corresponding topic in the |CONTENTS| tab. On the |!NDEX
tab, you can find help for a particular topic by typing a phrase into the text box at the top or by
selecting a topic from the list box at the bottom and then clicking the |DlSPLAY| button or by
double-clicking on the topic. The |SEARCH| tab enables you to search for specific words and
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IWEM User's Guide Running the IWEM Software
phrases in online |HELP|, instead of searching for information by category. Just follow the on-
screen prompts on the |SEARCH| tab to create and search a list of words in online |HELP|.
Pressing the |F11 key will automatically display an online Help screen that is appropriate for the
current IWEM screen that you are using. This information is also available via the last topic
listed on the |CONTENTS| tab: |HELP FOR SPECIFIC DIALOGS].
Finally, you can access definitions of keywords or parameters used in IWEM by clicking on any
underlined text in the WMU Data Requirements (3) or Roadway Data Requirements (4)
introductory screens (see Section 3.3). These definitions can also be displayed at any time by
choosing pEFiNUiON WINDOW) from the |HELP| menu. Data requirements for structural fills are similar
to those for landfills.
Once you find the information you need in online (HELP, you can use the main menu or the
command buttons at the top of the Help screen to skip to other sections of online |HELP| or to print
out a particular topic.
3.2.5.2 Getting Additional Help
If you have a technical question about installing or running IWEM, you should contact the EPA
Docket Center. This information center is a publicly accessible clearinghouse that provides up-
to-date information on RCRA rulemakings and responds to requests for regulatory publications
and information resources. Please note that the EPA Docket Center cannot provide regulatory
interpretations.
To get your technical questions about the IWEM software answered, please contact the EPA
Docket Center in any of the following ways:
E-mail: rcra-docket@epa.gov
Phone: 202-566-0270
Fax: 202-566-9744
In person: Hours: 8:30 am to 4:30 pm, weekdays, closed on Federal holidays
Location: WJC West Building
1301 Constitution Avenue, NW
Room 3334
Washington, DC 20004
Mail: U.S. Environmental Protection Agency
EPA Docket Center
RCRA Docket, Mail Code 2822IT
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
When contacting the RCRA Docket Center, please cite RCRA Docket number: EPA-HQ-RCRA-
1999-0032.
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For general support questions, please contact Taetaye B. Shimeles in any of the following ways:
E-mail: shimeles.taetaye@epa.gov
Phone: 703-308-8729
Mail: OSWER/ORCR
U.S. Environmental Protection Agency
Mail Code 5305P
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
3.2.6 How Do I Begin Using the IWEM Software?
The rest of this section provides a screen-by-screen tutorial that describes the data you are asked
to enter at each screen and your data entry options (for instance, some input data are required and
others are optional; Section 4 provides additional details on inputs). The guidance will assist you
in performing an IWEM analysis for an industrial WMU to determine the minimum
recommended liner design that will be protective of ground water given the RGCs you select or
enter. In addition, this section will also help in conducting an IWEM beneficial use analysis
using the structural fill and roadway modules. You will not need all the information provided
here, because this document addresses all WMU liner designs, as well as structural fills and
roadways, and several different levels of site-specific data. Follow only those subsections that are
applicable to your particular waste and source. Section 4 provides additional details on inputs.
3.2.7 How Long Will IWEM Run?
An IWEM evaluation can take anywhere from minutes to hours to complete, depending on the
complexity of the source, the number of liner scenarios that must be run, and the number of
constituents specified. Each combination of constituent and liner scenario or strip-layer
configuration requires one probabilistic Monte Carlo modeling run consisting of 10,000 model
realizations, and each of these realizations must run the computationally demanding fate and
transport simulations. Approximate runtimes for 10,000 Monte Carlo realizations on a typical
computer with a 2.5 GHz processor and 8 GB of RAM (this will differ on different computers)
are as follows:
• Land Application Units: about 4 minutes per constituent.
• WMUs with a single user-defined liner scenario: about 4 minutes per constituent.
• WMUs with three liner scenarios: 4 minutes per liner scenario per constituent, so up to
12 minutes per chemical depending on whether IWEM has to run one, two, or all three
liner scenarios to find a scenario that is below the benchmark.
• Structural Fills: about 4 minutes per constituent.
• Roadways: depends heavily on the complexity of the design and the properties of the
materials, but typically 3-12 minutes per constituent per strip.
These are only estimates, provided to give you an idea of what to expect. Many factors other than
those noted above can affect runtime.
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IWEM User's Guide Running the IWEM Software
3.3 Introductory Screens (Screens 1 through 5)
The text on Screens 1 through 5 provides a brief introduction to the IWEM software. Those
screens are
Screen 1: IWEM Overview (Figure 3-5A)
• Screen 2: Use of IWEM (Figure 3-5B)
Screen 3: WMU and Structural Fill Data Requirements (Figure 3-5C)
• Screen 4: Roadway Data Requirements (Figure 3-5D)
• Screen 5: Model Limitations (Figure 3-5E).
Specifically, these screens present an overview of IWEM statement regarding proper use of the
model and coordination with regulatory agencies, a list of data input requirements, and a
summary of model limitations.
By default, these screens are displayed when you start IWEM. You can turn that off by selecting
OPTIONS||NTRO SCREENS from the Menu Bar, then clicking on SHOW AT STARTUP so that it is unchecked.
You can also display these screens at any time from the OPTlONS|lNTRO SCREENS menu by clicking on
SHOW Now.
The key operational features of the introductory screens are described below.
A. Explanatory Text about IWEM. In this area of the screens, introductory text about
IWEM is displayed.
B. Go to Previous/Next IWEM Screen. Click the|PREVious| or |NEXT| button at the bottom
left or right of the screen to return to the previous introductory screen or proceed to the
next one.
C. Move Slider Down to View More Text. Depending upon your monitor settings, you
may need to use the scroll-bar on the far right side of these screens to display more text if
the complete text does not fit on the screen all at once.
D. Links. Click on any keyword displayed in blue underlined text to display a text box
containing a definition or other information about the underlined item. After reading the
definition, you can click on the |OK| button at the bottom of the dialog box to close the
text box and return to the Introductory screen.
E. Start New Evaluation. Click on the (START NEW EVALUATION! button to begin an analysis for
your leachate source type.
F. Open Saved Evaluation. Click on this button to open an evaluation you have previously
saved. This will open a standard Windows File Open dialog box, allowing you to browse
for your saved analysis. The file will have a .wem extension.
G. Close. This will close the introductory screens without starting or opening an evaluation.
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i
IWEM Overview (1)
>h» iVvwu;,.
«?fl, TlkBl
IfWEM Vei«ion 1J9 was tehraed m 2002 wid. a focu* an Musirial Waste Managem«nt in conventional wi
incoiputnted a new capability ID evaluate a roadway eonstnxrtad with industrial waste materials. fWEM Version 3JO enhanced the simulation of roadwuy
isccntuitts with additional control structures: ditches, drains, and gutters. The current version IWCM Version 3.1 includes the simulation at structural fill
iinos for trcuclieifll use nf industrial waste materials, such as coal fry ash ond spent foundry sand.
O8O: This program is dpsignni) In givn tnitilify manage**. (Agutatniy Mj«ncy MnH. Arid r.iti/HVS n simple Id ufin lonl In: (1) within
s.y.1 nirn. Fur NimlMIK. sinfucii mipiiuiiilirirnK. ami wattto pilrrs; (?) irvidiintn whMtiiri wmtfis MH huitiitili; tin liirnl »|qilii:niMiii; ;t ttruclixillill i;uiiMiui:li»n|>ii>jt)BlK.
• Ij •].!.<(.! I i'l I I "I
ipicrvrilns the r
o ground waler.
sulttt ol 1«lo anil t. un^poil tnodelinq ol cuiitdituenlK lei«.-hirH| ftwn a source ja WMU. *ti uu-linul Wl or intuKvay) Ihrouqh
Flu maifal prdviileB location- adjusted a« cwimg rBcommsrvdations lor each source type thai are (ailofedto aapecilic
tire than a detailed site-specific analysts.
liitm jt WMU. slittcluinl fill »i miufwny design.
WMlPH
prolBctrve l»i«r scenarios Iwn-'d on estimated conslrtucnt concentration in wuste k'acliale and lacatMiu [Mlpsled dnt i»Itit a
it can li« jit ulect ivcFy land applied.
lutts - The ntodfll provides one type of i ecoiruneodatMO based on benchmarks defined by ttie user:
1J An esUmatc of the protectiwrms associated with a roadway ihat contains industiiai waste ntaterials in structui id elcntcnls.
KK in:!urnl 1 itlfi Hncults Mm nwdel piovidnc mir type n< rccflmniRiMlalicin basnd nit bitnchninikK datmtat by the uafti:
An i-hliiiuJR nKlMi |mi1i:[!thfl:nrs\ .ii.<.ii^iiilr(l wifh sliiu^uriil lilK Unil ruriEiiin iridu^tinil w»str in;iti:iiiils. TlH-tmi'iil rhutii; nniti'ii.ik us till ini:luili!K:
TII I in Miuirliir ill luundfltimi nl piuking liilx, niHiK. imtl liuiklHHix; c»nMiiit:t»in nl bi[|hwny rnrfuuilanrn[H: liBin;) lit butinwpHx ID iK\'i\ti\\sr
Use of IWEM (2)
Wt: HlTwi',[ty i:r>i:iHi>ii4|4! ih^ M-.iri 'if rhis n
W*.' otso strongly encourage users ID rev
Management for A description oF the cnoi
Oitlinn I Irlp is nvnilnblft tin rvniy snrprn
lid wuikwilh hivilif.'i Sr.nli; At|cnr^|>iitii tu using HH^IIHI! in nwhing dctix-ians-/ayatding dniqn ilondanJi (or
Hie 'Assessing Risk" section of Cliaptti 7 4"PiDtccu'ng Ground watei Quality") in the Guide for Industrial Waste
nd fl discussion of hey pflriunctci s and r.i iticul issues thai iitfccl modeling results,
(A) IWEM Overview (1)
(B) Use of IWEM (2)
WMU and Structural Fill Data Requirements (3)
.'.V : •• - - -'!
lltaSSSI^wlw'^(W™* Q
to*of*ttm«*«rfinathK»ji
I ctimated leachotG nnd total Cdni:ri*rnliiir
Roadway Data Requirements (4)
-.-,
tt each KMttway stiifi
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IWEMUser's Guide
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Model Limitations (5)
~
is true of any mwtel. lt«* modeli» bused un » imrnturr uf •*
|1) H the stwl and aqurfw cannot be treated as urwfaioi pawns media, each consislwig til a single li^cr. f
d bedrock, IJIOUIH! iHittf.i How i« Iftnly In tin
ht; pieKoncc ciP pr«Pcrrntinl graunrt wnler llciw pmhwnys nr lityr^ring id Ihr
?) II Ilium i% a irmliiln nil |»fant! nr irftinr Wnn Ai^jruirs INiniii! I iijuiil (NAIM >\nnnr.nl nl rln;Ijuiilily Dr linnnnlh'
.(iwyo
These are the most important tinwUKion* of the modul. The IWEM Backgraiind Dcicunrenl and the Addendum to Ilic IWtM Dockgi ound Docwnent
of the assunifilions and tiniirattims of the model.
I
i • • > -••.-•" • ' ••
(E) Model Limitations (5)
Figure 3-5. Introductory screens (continued).
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3.4 Entering Inputs
In an IWEM evaluation, IWEM analyzes available site-specific data to develop liner
recommendations for WMUs or determine whether the incorporation of industrial materials into
a structural fill or roadway as specified in the design is appropriate. This section of the User's
Guide describes the input screens.
IWEM contains the following input screens and dialog boxes:
• Source Type (6)
• Source Parameters (7)
- Location of Well with Respect to Roadway (7a)
• Subsurface Parameters (8)
• Infiltration (9)
- Climate Center List (9a)
• Constituent List (10)
- Enter New Constituent Data (IQa)
- Add New Constituent (IQb)
- Add New Data Source (IQc)
• Constituent Properties (11)
• Reference GW Concentration (12)
- EditHBNs(12a)
• Input Summary (13)
3.4.1 Input: Source Type (Screen 6)
Figure 3-6 shows the Source Type (6) screen.
Source Type (G)
Select Source Type
r Landfill
• Waste Efel
Infiltration (9)
C Surface Impoundment / C Roadway
<~ Land Application Unit C Structural Fil
Facility Identification Information
Waste Is Us
'
Route 50
Anytown
12345
12/4/13
Jane Smith
Figure 3-6. Input: Source Type (6).
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The features identified in Figure 3-6 are explained in more
detail in the following paragraphs.
A. Choose Source Type. First, select one of the
choices from the [SELECT SOURCE TYPE| option list by
clicking on the appropriate radio button.
B. Enter Descriptive Facility Information. In the
text boxes located in the lower half of the screen,
enter the following information about the source
type being evaluated:
- Facility name
- Address of the source (street, city, state, zip)
- Date of waste constituent analysis
- Your name (name of the person performing the
evaluation)
- Any additional identifying information that you
would like to include
All information entered in these text boxes will be
included on the printed Evaluation Reports.
3.4.2 Input: Source Parameters (Screen 7)
An IWEM evaluation uses site-specific source data to assess potential ground water impacts. The
source parameters are entered on the Source Parameters (7) screen. This screen differs somewhat
for each source module; the four WMU screens are fairly similar and will be described together.
The structural fill screen is also similar to the landfill screen, however there are additional data
requirements that will be discussed separately. The roadway screen is quite different, due to the
different nature of the source, and is also described separately
following the structural fill screen.
Structural Fill or Roadway?
Applications that include reused materials
can range from the conceptually simple
(e.g., filling a borrow pit) to the very
complex (e.g., support for a multi-lane
roadway and component layers in an
adjoining embankment). The complexity of
the specific application will govern the
choice between a structural fill and a
roadway source term:
• Choose a structural fill source if the
application to be modeled can be
conceptualized as containing a single
layer of reused material that has the
same material and constituent
characteristics.
• Choose a roadway source if the
application to be modeled is more
complex and cannot be conceptualized
as a single layer of reused material; for
example if multiple layers with different
material and constituent properties are
present, or the layering structure within
the source varies.
See Section 3.4 of the IWEM Technical
Background Document for more
discussion.
For all input parameters
for which you enter site-
specific values,
remember to type in a
brief justification or
explanation of this value.
This information is
required and will be
included in the printed
report.
3.4.2.1 WMU Source Input Parameters
The complete list of all WMU parameters is shown in Table 3-1.
The table uses the following symbols:
• A filled circle in the table means the parameter is required
for that WMU. You must provide a site-specific value for
this parameter.
o An open circle means the parameter is applicable to the WMU but not required. IWEM
will use a site-specific value if you enter one. If you do not have this data, IWEM gives
you the option to select a default value, or distribution of values. These default values
are generally the median values of the distributions of values.
NA NA means it is not applicable to the WMU.
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Table 3-1. WMU Source Input Parameters
Parameter
Area of the WMU
Distance to well
Depth of WMU
Ponding depth
Operational life of WMU
Depth of WMU base below ground surface
Sludge thickness
Distance to nearest surface water body
Brief explanation for each site-specific value
Land
Appl. Unit
•
0
NA
NA
0
NA
NA
NA
•
Landfill
•
0
•
NA
NA
0
NA
NA
•
Surface
Impound.
•
0
NA
•
0
0
o
o
•
Waste
Pile
•
0
NA
NA
0
0
NA
NA
•
The above inputs are discussed in more detail in Section 4.2.1. The specific source input screens
for land application units, landfills, surface impoundments, and waste piles are shown in Figures
3-7A through D respectively. The features identified in Figure 3-7 are explained in more detail in
the following paragraphs.
A. Enter Available Site-Specific Values. Table 3-1 lists the inputs and identifies which are
required and which are optional. See Section 4.2.1 for detailed discussion of the inputs.
B. Enter Data Source. For all parameters for which you enter site-specific values,
remember to type in a brief explanation of this value. Examples of data sources might
include "site measurements" or a reference to a specific report or other reference. This
information is required and will be included in the printed report.
C. Apply Defaults. Click this button to fill in default values for any optional inputs for
which you choose not to enter site-specific data.
D. Enter or Select the Distance to the Nearest Surface Water Body. For a surface
impoundment, you must also either enter a value for the distance to the nearest
(permanent) surface water body or choose one of the default selections for this input
parameter. This parameter is used in the calculation of ground water mounding to ensure
the model uses a realistic infiltration rate.
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(A) Land Application Units
(B) Landfills
-
Zl
(C) Surface Impoundments
(D) Waste Piles
Figure 3-7. Input: Source Parameters (7) for WML) sources.
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3.4.2.2 Structural Fill Source Input Parameters
Structural fills uses the same input parameters as landfills. For example, area and depth of the fill
are required parameters; distance to well and depth of base below ground surface are optional
(defaults are available). This module also requires three additional parameters:
• Effective bulk density: A material bulk density must be provided. This parameter is
required for calculating how long a contaminant leaches from the structural fill layer
containing industrial material. The best source for this parameter would be engineering
design reports.
• Effective hydraulic conductivity: A material hydraulic conductivity must be provided.
This parameter is required for determining the limiting value of infiltration through the
structural fill layer containing industrial materials. Again, the best source for this
parameter would be engineering design reports. The IWEM Technical Background
Document (U.S. EPA, 2015a) provides values for representative materials in Table 6-17
in units of cm/sec. IWEM requires units of m/yr for hydraulic conductivity. Multiplying
values in IWEM Technical Background Document Table 6-17 by 315,576 will convert the
units to m/yr.
• Volume fraction occupied by leachable material: The volume fraction of the fill that is
composed of leachable material must be provided.
The above inputs are discussed in more detail in Section 4.2.2. The source input screen for
structural fills is shown in Figure 3-8.
J3 Input
Source Type (6)
Source Parameters (7)
Subsurface Parameters (8)
This screen allows you to enter or change sttudutal till potarnptprs Justifications tot paiarneiers are required.
1000
1.5
300
.75
Data Source
Default
Facility records
Facility records
Default
Facility records
Facility records
Facility records
ApplyQetaults
Figure 3-8. Input: Source Parameters (7) for structural fill sources.
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IWEM User's Guide Running the IWEM Software
The features identified in Figure 3-8 are explained in more detail in the following paragraphs.
A. Enter Available Site-Specific Values. Both required and optional inputs are listed
above. See Section 4.2.2 for detailed discussion of the inputs.
B. Enter Data Source. For all parameters for which you enter site-specific values,
remember to provide a brief explanation of this value. Examples of data sources might
include "site measurements" or a reference to a specific report or other reference. This
information is required and will be included in the printed report.
C. Apply Defaults. Click this button to fill in default values for any optional inputs
parameters for which you choose not to enter site-specific data.
3.4.2.3 Roadway Source Input Parameters
The roadway source module requires more inputs than the WMU sources; a complete list of all
roadway source parameters is shown in Section 4.2.3 (see Table 4-3). For roadways, all of the
source parameters are required. This means that you must provide site-specific values for every
parameter. IWEM does not currently provide any default parameter values; however, a discussion
of roadway parameters provided in Section 4.2.3.
Location of Well With Respect to Roadway (Screen 7a)
When you are entering data for a new evaluation, IWEM will display a dialog box (Screen 7a,
Figure 3-9) where you must identify the general setting that identifies at a general level the
spatial arrangement of the roadway, the ground water flow, and the receptor well. You will
specify these inputs more specifically later; for now, IWEM just needs the general orientation.
This box appears after you choose a roadway source on the Source Type (6) screen and prior to
display of the Source Parameters (7) screen. If you have opened a saved evaluation, this screen
will not appear unless you opt to change the general setting.
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Location of Well with Respect to Roadway (7a)
We need to determine some basic relationships between the roadway, the direction of
groundwaterflow, and the location of the receptor well. Consider an orientation where the
direction of groundwaterflow is left to right.
flow
n
The angle between the roadway and the groundwaterflow is
The receptor well is in (Region I
•»• |
OK
Figure 3-9. Input: Location of Well With Respect to Roadway (7a).
The features identified in Figure 3-9 are explained in more detail in the following paragraphs:
A. Select an Angle Range. You have two options for the ground water flow angle range: 0
to 90 degrees or greater than 90 degrees. The upper bound on the angle is 180 degrees.
Use the drop-down control to make the appropriate selection.
B. Select a Well Location Setting. You have two options to specify the general location of
the well. The correct selection depends upon where the well is with respect to the
perpendicular line shown in green in the diagram in the screen. If the well is above the
line, select Region I; otherwise, select Region n.
C. Click |OK| to Close Dialog. When you click |OK|, the next screen, the Source Parameters
(7) screen will be displayed.
Roadway Source Parameters (Screen 7)
Figure 3-10 shows the overall roadway input screen. This screen contains several distinct areas:
• General inputs (number of roadway strips, number of drains, and roadway segment
length) are shown at the top of the screen
• Well geometry inputs (shortest distance to nearest receptor well, distance along roadway
edge from midpoint to location of previous measurement, angle between the ground water
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flow direction and the edge of the roadway, and location setting of the receptor well with
respect to the roadway and the ground water flow direction) are shown at the right of the
screen.
• Five tabs for feature-specific inputs (geometry, layer properties, ditch properties, drain
properties, and flow characteristics) are shown in the center left of the screen.
The inputs are discussed in more detail in Section 4.2.3. The features of the overall screen are
described below Figure 3-10. The specific tabs are shown and described following that.
13 Input
Source Type (6)
Th s screen allows you to enter or change rosdwsy parameters.
Number of roadway strips (include ditches in this count):
Number ot drains i' applicable only when a ditch is present):
:e Parameters (7) 1 Subsurface F
^0^3 JB
: \2 -"'"'Roadway segment length (rn): H 20
Subsurface Parameters (8)
ntiHiation (!3J
(5) Flow Characteristics
(4) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
umbers increase with distance trom well (1 is closest).
Fiogdwav Geoirpirv
Strip #
1
2
3
4
5
6
7
ft
Strip Type
Ditch
Embankment
Paved Area
Paved Area
Median
Paved Area
Paved Area
QhnnUaK
Width (m)
3
3
3
3
3
3
3
T
# of Layers
1
2
3
3
2
3
3
9
-
numbers increase trom bottom to top.
Drain Geometry-Strips
t
Drain ID
Drain 1
Drain 1
Drain 2
Drains strip
3
1
6
*
—
Dran GenrTiPitv- luiiiiquiaiion
}
Drain ID
Drain 1
Drain 2
Drains to
Ditch in Strip
1
q
Drain is
above layer
1
1
-
T
Change Well Geometry
Shortest distance betwei
roadway edge and thi
monitoring well (m): "~
Distance along roadway froi
Dwas made to the mi
the drawing) (m)
Angle between roadway and groundwater flow (degrees): [90
ClearRoeid'vVrtV Gprimp.trv«nd Start Again
^Lj, ^
Next»
Figure 3-10. Input: Source Parameters (7) for Roadways: Overview.
The features identified in Figure 3-10 are explained in more detail in the following paragraphs.
A. Enter the Number of Strips. Roadways are conceptualized as a collection of strips that
can represent one of the following roadway components: shoulder, embankment, travel
lane, median, or ditch. The minimum number of strips is 1 and the maximum is 15. The
number of strips is a required input.
B. Enter the Number of Drains. You can define up to two drainage layers, or drains, in a
roadway cross section. A drain is comprised of a highly permeable material layer and a
collector pipe. You must define at least one ditch in the roadway cross-section before you
can add a drain. Thus, the number of drains is an optional parameter and the text box
becomes active only after the first ditch is defined in the Geometry tab, as discussed
below.
C. Specify the Length of the Roadway to be Modeled. A roadway segment must be
identified that represents all or a portion of a longer roadway that can be approximated by
a rectangle. The length of that idealized line is a required parameter. If you used a scaled
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IWEM User's Guide Running the IWEM Software
drawing to determine your well location setting for the Location of Well with Respect to
Roadway (7a) screen, you determine this distance from the drawing.
D. Reset the Setting Scenario for the Receptor Well Location. The graphic displayed on
this screen corresponds to the selection made on the Location of Well with Respect to
Roadway (7a) screen. If you wish to change the receptor well location setting, click the
[CHANGE WELL GEOMETRY] button to display the Location of Well with Respect to Roadway
(7a) screen again, and make your selection. Be advised that if you change the well
location setting, you will need to re-enter distances D and L (defined below), and the
angle between the roadway and the ground water flow direction.
E. Specify the Distance D. Two distances are required to properly locate the receptor well
with respect to the roadway. The first distance is D, which represents the shortest distance
from the down-gradient edge of the roadway to the receptor well. This distance
corresponds to the perpendicular distance from the roadway edge to the receptor well. If
the receptor well is located beyond the end of the modeled roadway segment, then the
distance D is determined by assuming the straight roadway extends out to a point such
that a perpendicular line can be constructed from the roadway edge to the receptor well.
The length of that constructed line is D. If you used a scaled map or drawing to determine
the well location setting, that document can be used to determine distance D. The use of
IWEM for well location of less than 5 m from the source is not appropriate (See
section 6.1.4 of the IWEM Technical Background Document, U.S. EPA, 2015a).
F. Specify the Distance L. The second required distance for locating the receptor well is L,
which represents the distance measured from the midpoint of the roadway segment to the
point on the roadway edge where the distance D was determined. This definition also
applies to the scenario where the receptor well is located beyond the end of the modeled
roadway segment. If you used a scaled map or drawing to determine the well location
setting, that document can be used to determine distance L.
G. Specify the Angle between the Roadway and Ground Water Flow Direction. The
angle created between the roadway and the direction of ground water flow AWAY from
the roadway is required to accurately determine how much dissolved constituent reaches
the receptor well. The size of the angle is limited to a range specified on the preceding
dialog (e.g., between 0 and 90 degrees, or greater than 90 and less than or equal to
180 degrees). If you used a scale drawing or map to determine the well location setting,
that document can be used to determine the angle.
H. Reset Roadway Cross-section Geometry. If you click |CLEAR ROADWAY GEOMETRY AND START
AGAIN| button, all the entries one has made in the boxes and grids that define the roadway
geometry will be removed and source parameters will be started over from scratch.
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It is possible that your combination of receptor location parameters defines a scenario that
cannot be simulated by IWEM or EPA CMTP.
EPACMTP can only simulate a receptor well that is down-gradient of the leachate source where
ground water flow is perpendicular to the source of leachate. In order to accommodate non-
perpendicular ground water flow directions, it is necessary to apply a geometric transformation to
your conceptual model. The details of the transformation are presented in Appendix C of the IWEM
Technical Background Document and can be visualized in IWEM Technical Background Document
Figure C-6. The transformation allows IWEM and EPACMTP to represent non-perpendicular flow as
perpendicular.
If it you specify a combination that IWEM cannot simulate, you will see the following error message.
See Section 4.2.3.1 for more details on specifying location parameters to avoid this error.
As specified, the relationships between the roadway, the angle of ground water flow, and the distances to the receptor well (when transformed for
modeling) result in a scenario that the ground water model cannot simulate - the receptor well is somewhere behind the down-gradient edge of the
roadway, Please consult IWEM HELP for additional details press Fl].
OK
Figure 3-11 shows the Geometry tab on the Source Parameters screen for roadways.
I
(5) Flow Characteristics
(4) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
Strip numbers increase with distance from well (1 is closest).
Strip #
Roadway Geometry
Strip Type
Ditch
Embankment
Paved Are a
Paved Area
Median
Width (m)
# of Layers
>
Drain GF;
Drain ID /
Drain 1 '
Drain 1
Drain 2
iitnetry-Strijps
Drains strip
3 '
A
6
A
T
Figure 3-11. Input: Source Parameters (7) for Roadways: Geometry.
The features identified in Figure 3-11 are explained in more detail in the following paragraphs.
A. Select the Strip Type using Drop-down List. You must identify the general character or
nature of each strip (paved area, median, shoulder, embankment, or ditch). If you click on
any of the cells beneath the heading |STRIP TYPE|, a drop-down list control (w ) becomes
visible. Clicking on the control displays a list of available strip types; select a strip type
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IWEM User's Guide Running the IWEM Software
by clicking on the item in the list. Designating a Strip Type is required. If a strip is
defined as a Ditch, the text box for the number of drains is enabled (see Item C above).
B. Enter Strip Width and Number of Layers. You must provide the width of that strip and
the number of material layers used in constructing that strip. The best source for these
parameters would be construction design drawings for roadways. In addition, maps, plan
drawings, and areal photos may also provide useful information.
C. Select a Drain Using Drop-down List. Assuming you have defined at least one drain,
you will need to associate a drain with the one or more strips that contain that drain. The
first step is to select a drain from the drop-down list that appears by clicking on the cell
beneath the heading |DRAIN ID|. Clicking a cell will cause a drop-down list control (**".) to
become visible. Clicking on the control displays a list of available drain IDs; select a
drain ID by clicking on the item in the list.
D. Associate Strips with a Drain Using Drop-down List. This is second step to associate a
drain and strip. Use the drop-down list beneath the heading (DRAINS STRIP|, to choose the
strip number associated with the drain.
E. Identify the Ditch Strip Receiving Drainage Water. Each drain must be connected to a
ditch. You may connect two drains to a single ditch, as long as the ditch is between the
drains. Use the drop-down list beneath the heading (DRAINS TO DITCH IN STRIP|, to choose the
strip representing a ditch that receives drainage from each drain.
F. Specify where Drain is in Cross-section. As mentioned above in Item C, the layering
(and material) configuration beneath a drain must be identical across strips serviced by
that drain. You locate the drain by specifying the layer number directly beneath each
drain.
Figure 3-12 shows the Layer Properties tab on the Source Parameters screen for roadways.
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(1) Geometry
(5) Flow Characteristics
(4) Drain Properties
[ ^^^ (3) Ditch Properties
^F*i
Layer numbers increase from bottom to top. 1
Layers below each must be identical in all aff
1(2) Layer iprc
=cted strips.
\ Layer Props
K
Strip
Num
1
2
2
3
3
3
A
A
A
5
5
E
6
Strip Type
Ditch
Embankment
Embankment
Paved Area
Paved Area
Paved Are a
Paved Area
Paved Area
Paved Area
Median
Median
Paved Area
Paved Area
Layer
Num
1
1
2
1
2
3
1
2
3
1
2
1
2
Is Below
Drain
1
1
2
Layer Type
Fill
Fill
Fill
Subgrad
Base
Pave me
Subgrad
Base
Pave me
Fill
Fill
Subgrad
Base
Thic
(m)
.45
•parties!
F P P
p / /
pess
.6
.75
.6
.3
.3
.6
.3
.3
.6
.75
.6
.3
Hydrauli*
Cond (m 'yr)
1
1.095 '
.0017
3.139
.0073
3.139
3.139
.0073
3.139
3.139
.0017
3.139
.0073
3.139
Bulk Density
(g/cm3J
2
2
2
2
2
2
2
2
2
2
2
2
2
Figure 3-12. Input: Source Parameters (7) for Roadways: Layer properties.
The features identified in Figure 3-12 are explained in more detail in the following paragraphs.
A. Use Drop-down List to Specify Layer Type. Use the drop-down list beneath the heading
|LAYERTYPE|, to specify the layer type of each layer for each strip (subbase, base, fill,
pavement, subgrade, or grade).
B. Enter Layer Thickness. For each layer in all strips, a thickness must be provided. This
parameter is required for calculating how long a contaminant leaches from a roadway
layer containing industrial materials. Again, the best source for this parameter would be
engineering design drawings or a design report.
C. Enter Material Hydraulic Conductivity. For each layer in all strips, a material hydraulic
conductivity must be provided. This parameter is required for determining the limiting
value of infiltration through the layers of a strip. Again, the best source for this parameter
would be engineering design reports. The IWEM Technical Background Document
provides values for representative materials in Table 6-17 in units of cm/sec. IWEM
requires units of m/yr for hydraulic conductivity. Multiplying values in IWEM Technical
Background Document Table 6-17 by 315,576 will convert the units to m/yr.
D. Enter Material Bulk Density. For each layer in all strips, a material bulk density must be
provided. This parameter is required for calculating how long a contaminant leaches from
a roadway layer containing industrial materials. Again, the best source for this parameter
would be engineering design reports.
Figure 3-13 shows the Ditch Properties tab on the Source Parameters screen for roadways.
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(2) Layer Properties
(1) Geometry
(5) Flow Characteristics
(A) Drain Properties
1(3) Ditch Properties!
Ditch Properties
Strip
Manning's
.016
Slope
(m/m)
1E-03
Max
depth (m)
Gutter
.016 , |lE-08y |1 . | F .
Q O GO
Between
strip
and
strip
Figure 3-13. Input: Source Parameters (7) for Roadways: Ditch properties.
The features identified in Figure 3-13 are explained in more detail in the following paragraphs.
A. Enter Manning's n for each Ditch. For each ditch strip, you must provide a value for
Manning's roughness coefficient, n. This parameter is required for estimating the ditch
inflow/outflow rate calculated from cross-sectional average velocity along the ditch.
Again, the best source for this parameter would be engineering design drawings or a
design report. Representative values are provided in Section 4 (Table 4-4).
B. Enter Slope for each Ditch. For each ditch strip, slope of the ditch bed (dimensionless)
must be provided. The slope can be calculated as the change in elevation of the ditch bed
over its length divided by the length of the ditch. The slope should be set to zero if there
is stagnant water in the ditch (no flow).
C. Enter the Maximum Water Depth for each Ditch. To safeguard against possible
unrealistic values of water depth in the ditch, the estimated water depth is limited to this
maximum water depth. The maximum water depth corresponds to the height from the
ditch bed to the lowest cresting side.
D. Use Check Box to Indicate the Presence of a Gutter. Checking the box indicates that a
surface gutter is present in the roadway cross-section and the gutter is associated with a
specific ditch strip. A gutter is used to divert some or all of the runoff water from strips
"above" the gutter, away from the associated ditch and out of the modeled system. You
can specify how much of the runoff is not diverted in Item A of the Flow Characteristics
grid, discussed below.
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E. Use Drop-down List to Place Gutter between Strips. If a gutter is present, you locate
the position of the gutter between two strips using the drop-down lists beneath the
headings [BETWEEN STRIP| and |AND STRIP].
Figure 3-14 shows the Drain Properties tab on the Source Parameters screen for roadways.
[ (3) Ditch Properties
f (2) Layer Prop erties
J_
(1) Geometry
f (5) Fl ow Ch aracte ri sti cs
i(4) Drain Properties)
Drain Properties
ID Thickness
(m)
> Drain 1 .15
DrainE .15 /
d
Hydraulic
Conductivity (m/yr)
1.095E+07
1.095E+Q7y
d
Bulk Density
(g/cm"3)
2
2 /
d
Figure 3-14. Input: Source Parameters (7) for Roadways: Drain properties.
The features identified in Figure 3-14 are explained in more detail in the following paragraphs.
A. Enter Drainage Layer Thickness. A thickness of the highly permeable material must be
provided each drain. This parameter is required for calculating how long a contaminant
leaches from the drainage layer. The best source for this parameter would be engineering
design drawings or a design report.
B. Enter Drainage Material Hydraulic Conductivity. For each drainage layer, a material
hydraulic conductivity must be provided. This parameter is required for determining the
limiting infiltration rate across layers in a strip. Again, the best source for this parameter
would be engineering design reports. Values for representative materials are provided in
the IWEM Technical Background Document in Table 6-17 in units of cm/sec. IWEM
requires units of m/yr for hydraulic conductivity. Multiplying values in IWEM Technical
Background Document Table 6-17 by 315,576 will convert the units to m/yr.
C. Enter Drainage Material Bulk Density. For each drainage layer, a material bulk density
must be provided. This parameter is required for calculating how long a contaminant
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leaches from the drainage layer. Again, the best source for this parameter would be
engineering design reports.
Figure 3-15 shows the Flow Characteristics tab on the Source Parameters screen for roadways.
) Drain Properties
(3) Ditch Properties
(2) Layer Properties
| (1) Geometry
i(5) Flow Characteristics!
Flow Percentages to Ditch Strips
Item
Strip 1
Strip 9
Drain 1
Drain 2
Information
Percent of roadway runoff that reaches
ditch beyond gutter
Percent of roadway runoff that reaches
ditch beyond gutter
Percent of flow in Drain 1 that reaches
ditch
Percent of flow in Drain 2 that reaches
Value (%)
50 v
50 /
A
-o d
-o
T
Flow Paths to Ditch Strips
>
Overland flow from strip
2
3
A
flows into ditch strip
1
1 —
1
-a
A
T
Figure 3-15. Input: Source Parameters (7) for Roadways: Flow Characteristics.
The features identified in Figure 3-15 are explained in more detail in the following paragraphs.
A. Enter a Percentage of Roadway Runoff that Reaches Ditch Beyond Gutter. This
parameter must be provided when a gutter defined for a ditch. A gutter is used to divert
some or all of the runoff water from strips "above" the gutter, away from the associated
ditch and out of the modeled system. Including a gutter is optional. The value you supply
here, a percentage ranging from 0 to 100, specifies how much of the runoff is NOT
diverted by the gutter. If a gutter is not present, then 100% of the runoff should reach the
ditch. If a gutter is present, the percentage should be equal to the ratio of the width of all
strips between the gutter and the ditch to the width of all strips that are associated with
the ditch.
B. Enter a Percentage of Drainage Flow that Reaches each Ditch. This parameter
accounts for the possibility that not all infiltrating water, and the constituents dissolved in
that water, is diverted by the permeable layer or drain to its associated ditch. A value must
be provided for each defined drain, a percentage ranging from 0 to 100, to indicate how
much of the infiltrate entering the drain is diverted to the ditch. A value of 0 indicates that
no drainage flow will reach the ditch. A value of 100 indicates that all infiltrate entering
the drain will be diverted to the ditch. Selecting a value for a drain will depend on the
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continuity of the drain in the direction of travel. If the drain is represented as a continuous
layer of highly permeable material, then the value would tend to be low. If, however,
drainage pipe is used at intervals, then the value could be estimated as a ratio of the area
drained by the drainage pipe to the entire area of the roadway underlain by the drain.
C. Use Drop-down List to Assign Overland Flow from every Strip to a Ditch. If at least
one ditch is defined, you will be asked to associate every non-ditch strip with a ditch. The
association directs the model to apply any runoff from that strip to the specified ditch. For
roadway cross-sections were two ditches are defined, the association of strip runoff to
ditches cannot create a scenario where runoff flows cross each other - IWEM will prevent
that scenario. Use the drop-down list beneath the heading |FLOWS INTO DITCH STRIP], to assign
the overland flow from each non-ditch strip to a ditch strip.
3.4.3 Input: Subsurface Parameters (Screen 8)
The Subsurface Parameters (8) (Figure 3-16) screen is where you enter site-specific data that
describes the subsurface environment at your site.
£] Input
° I a Ua-l
Source Type (6)
Source Parameters (7)
j
Subsurface Parameters (8)
Infiltration (9)
This screen allows you to enter or change the subsurface parameters.
You MUST select a Subsurface Environment. If you select 'unknojtfri' then the default values will be used for all parameters. In addition, you MAY enter values for one or more hydrogeologic
pararneter(s). Data sources are required.
Select the Subsurface Environment:
Data Source
Default [see Note 1]
Default [see Note 1]
Default [see Nate 1]
Default [see Note 1]
Default [see Note 1]
Restore
Nole 1: See IWEM Technics! E!9r:f ground Docuirienr Section 4.2.3.1. Press F1 for more information
« Previous
Figure 3-16. Input: Subsurface Parameters (8).
The features identified in Figure 3-16 are explained in more detail in the following paragraphs:
A. Select Subsurface Environment. IWEM includes 12 different types of subsurface
environments that represent different hydrogeological settings. Section 4.3.1 provides
more information on the subsurface environments. If you do not know what type of
environment is appropriate for your site, select "unknown." In effect, the "unknown"
subsurface environment is an average of the 12 known environments. You must select
one of the available subsurface environments.
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B. Enter Available Site-Specific Values. You may enter values for any subsurface
parameters for which you have site-specific data. You need not enter data for every
parameter. If you do not enter site-specific data, IWEM will use a default or distribution,
depending on the selected subsurface environment:
- For the unknown subsurface environment, IWEM will use the default value displayed
(in the default value column). The value displayed on the screen will be input to the
model as a constant value (no distribution of values is used). Each default value
corresponds to the mean value of the available data for that parameter from all 12
subsurface environments. This value is representative of a national average. The
displayed value in the data source column and the phrase "Default [see Note 1]" in the
data source column indicate that IWEM will use the displayed default value for this
input parameter in the analysis.
- For all other subsurface environments, IWEM will use a distribution of parameter
values that corresponds to the specified subsurface environment to generate values.
The word "Distribution" displayed in the default value column and the phrase "Monte
Carlo [see Note 1]" in the data source column indicate that IWEM will randomly
select values for this parameter from the appropriate distribution during the analysis.
The distributions reflect the range of values that each parameter can have.
C. View or Edit Data Source for Each Value. You must document the data source or
explain the value used for any site-specific values you enter. IWEM provides a default
data source for all optional data. All data sources or explanations for default or user-
specified data are included in the printed report.
D. Click to Restore Default Values. Clicking this button will clear any site-specific values
and data sources you have entered and reset the default values.
For roadway sources, the information provided on screens 7, 7a, and 8 completely describe the
roadway setting as required by IWEM. When you click |NEXT| on screen 8, IWEM will check your
inputs to evaluate whether the setting you have described is physically possible and consistent with
the EPACMTP model. Specifically, IWEM verifies that:
• the bottom of the roadway is above the water table, and
• the aquifer can support a typical drinking water well.
If you do not specify the depth to ground water, IWEM will postpone this evaluation until the
Infiltration (9) screen has been completed. IWEM will notify you if either of the above conditions is
violated with a message box informing you of your options. If none of the suggested options is
consistent with the conditions at your site, IWEM is not appropriate for your site, and you should
consider a detailed, site-specific analysis. Consult Section 4.3, or the IWEM Technical Background
Document, for more information on the assumptions built into the EPACMTP model which may make
it unsuitable for a particular site.
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3.4.4 Input: Infiltration (Screen 9)
On the Infiltration (9) screen, you enter or select the infiltration rate that IWEM will use in
modeling your site. In IWEM, infiltration refers to the flow rate per unit area (m3/yr per m2 or
m/yr) of water that migrates downward through the surface of a source into the source interior;
recharge (m/yr) refers to the natural precipitation that infiltrates to the subsurface outside the
footprint of the source.
This screen differs significantly for WMUs and roadways, so they will be presented separately.
3.4.4.1 WMU Infiltration Inputs
For WMUs, the general appearance of this screen is the same, but the components shown vary
somewhat depending on whether you choose to enter site-specific infiltration data and what
WMU type you are working with. Figure 3-17 shows the various formats of the screen for
WMUs.
The features identified in Figure 3-17 are explained in more detail in the following paragraphs:
A. Specify Infiltration Data Option. Displayed at the top of screen 9 for WMUs is the
following question: "Do you have a site-specific value for infiltration rate?" Select one
of the two radio buttons to indicate yes or no.
If you choose |No|, the evaluation will be performed for the default liner scenario(s) no
liner, single clay liner, and composite liner for landfills, surface impoundments, and waste
piles; no liner for land application units).
If you choose |YES|, the evaluation will be performed for your specified WMU infiltration
rate. This liner scenario is referred to as a "user-defined liner". This is the appropriate
option to choose if you know the infiltration rate for your particular liner design.
B. Choose Soil Type. Regardless of whether or not you have a site-specific value for
infiltration, you need to specify the soil type and geographic location of the WMU so that
the model can generate a recharge rate for your site. Additionally, if you do not have a
site-specific value for infiltration, the specified soil type and geographic location are used
to estimate the infiltration rate for your site for the standard liner scenarios for landfills,
land application units, and waste piles (infiltration rates for surface impoundments are a
function of the ponding depth).
First, select the appropriate soil type from the choices shown in the |SoiL DATA| dialog box:
- Coarse-grained soil (sandy loam)
- Medium-grained soil (silt loam)
- Fine-grained soil (silty clay loam)
- Unknown soil type.
If you choose one of the three default soil types (coarse, medium, or fine), the Monte Carlo
process will randomly assign values for the required soil-related input parameters according to
probability distributions that are appropriate for the specified soil type. If you choose "unknown
soil type" (the default selection), the Monte Carlo process will randomly select one of the three
possible soil types in accordance with their nationwide frequency of occurrence. For more
details, please see Section 6.5.2 of the IWEM Technical Background Document.
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51 US
louiM PwajrW SutitrurtBLTi ParflintfluiM (El
Da you h5v(r vn-visvuAc irrf iMJflnT /
(A) Infiltration: Source Specific
Dayaub!
~ Ysv I hurts SUB-SpratC NWMBfti RVhrittinilMi«paiUdbvouiuMrdelntaln«. tS f.
Sod CM*
nBftWKfllBdBSOlVT"1
i 9 !JL.-,i,L-.sLiifv.-uiiML piling 10 we!.-*
w—i««i-ta««r.M.r
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• 1 1
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InttinMnRWisim/yi)^
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i™253SSSS«SiiiiS nM
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VKMrOhMlMl '
NC
- ftidwiw>RM»W)rtj
H 1
(B) Infiltration: Not Source Specific, landfill and surface
impoundment
a
' Yn.llMv*Sto>Sp«C*cln«»alnn R«iitW»rtlbei»oor*il>oryD«niB»r(f*(ntdtin«r A Mo.lttonrtltBwSrtB-SpiCils'tifBiWon P«iutli-^rifier*purtrdlerUIB*rtouHkw«M»(*f
SoiDHH-
^
L,, ni. .,.,,-!. r-t-
/a
(C) Infiltration: Not Source Specific, waste pile (D) Infiltration: Not Source Specific, land application unit
Figure 3-17. Input: Infiltration (9) for WMUs.
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IWEMUser's Guide
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C. Enter Site-Specific Infiltration Rate and Data Source. If you said you had site
specific infiltration rate data, enter your site-specific infiltration rate and provide a brief
explanation of the data source for your value in the Data Source column. Both the value
and your explanation will be included in the printed report.
D. Select Waste Type According to Permeability. For a waste pile, you must also specify
the waste type permeability (this value is used in determining the no-liner and single clay-
liner infiltration rate). There are three choices for waste permeability: high (4.1 x io~2
cm/sec), medium (4.1 x io~3 cm/sec), and low (5.0 x io~5 cm/sec). These values are
representative of wastes commonly disposed in waste piles.
E. Choose Climate Center. For unlined units, except surface impoundments, and for single
clay-lined landfills and waste piles, infiltration and recharge rates for representative
regions and locations, or "climate centers," around the country have been calculated based
on meteorological data and soil type. By choosing the climate center that is representative
of the modeled WMU site, you can use the infiltration and recharge rate(s) for this
climate center as an estimate of the rate(s) expected at your site. In many cases, selecting
the climate center that is closest to your site will provide the best estimate of infiltration
rate. A map of the IWEM climate centers is presented in Figure 4-9 of Section 4.3.2 of
this document. You should, however, verify that the overall climate conditions at the
selected climate station are representative of your site. Section 6.4 of'the IWEMTechnical
Background Document provides a detailed discussion of how the infiltration rates were
developed.
To choose a climate center, click on the |ViEW
CITIES LIST| button. The dialog box shown in
Figure 3-18 will appear.
El.Select Sort Order. You can sort the
climate centers alphabetically by city or
by state by choosing one of the |SORT BY|
options.
E2. Slide Down to Scroll through List. You
can view the entire list using the |ARROW|
keys on the keyboard or by manipulating
the scroll bar to the right of the list.
E3. Select Nearest Climate Center. Select a
climate center by using the |ARROW| keys
to highlight an entry, or by clicking on a
single entry with your mouse.
E4. Verify Selected Climate Center. You
can verify that the correct climate center
is selected by looking at the city name
shown at the bottom of this dialog box.
E5.Enter Selected Climate Center and
Return to Infiltration (9) screen.
Climate Center List (9a)
ra
Please select a city from this list:
El Paso TX
Ely NV
Fairbanks AK
Flagstaff AZ
Fresno OA ^^
Glasgow MT
Grand Island NE
Grand Junction CO
Great Falls / MT
Hartford
Honolulu
Indianapolis
Ithaca
Jacksonville
Knoxville
Lake Charles
Lander
Las Vegas
Lexington
little
Rock
Los Angeles
CT
HI
IN
NY
FL
TN
LA
WY
NV
KY
AR
CA
V
]
"•
You selected Greensboro, NC
Cancel
r Sort by C%
(~ Sort by State
Figure 3-18. Input: Climate Center List
(9a).
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Clicking on the |OK| button or double-clicking on the highlighted entry will enter your
selection and return you to the Infiltration (9) screen.
F. View Infiltration Rate(s). If you did not enter a site-specific infiltration, once you have
selected a soil type and the nearest climate center, IWEM will estimate the infiltration
rates for each of three standard liner scenarios (no liner, single clay liner, and composite
liner) for your WMU site (note that only the no-liner scenario is evaluated for land
application units). The resulting value(s) are listed in the table at the bottom left of the
infiltration screen.
G. View Recharge Rate. Once you have selected a soil type and the appropriate climate
center, IWEM will estimate the recharge rate for your WMU site. The resulting value is
listed in the table at the bottom right of the infiltration screen.
3.4.4.2 Structural Fill Infiltration Inputs
Infiltration inputs for structural fills are the same as for landfills (see Section 3.4.4.1). Infiltration
rates for structural fills can be site specific (see Figure 3-17A) or non-site-specific (see Figure 3-
17B).
3.4.4.3 Roadway Infiltration Inputs
The Roadway version of the infiltration screen differs from the WMU version because the
Roadway source module requires you to specify an infiltration rate and a runoff rate for each of
the roadway-source strips defined on the Source Parameters (7) screen. It also requires
information on precipitation and evaporation for each ditch. The Infiltration (9) screen for
roadways is shown in Figure 3-19.
Soil Data
Please select a soil to representthe
predominate soil type surrounding the
roadway for soil parameters and
recharge determination:
I CoarsB-qrained soil (sandy loam)
Fine-grained soil (siity clay loam)
Unknown soil type
- Local Climate Data
St Climate Center
View Cities List
Selected city
Jsei SpHiutieri Initiation hate- I'ln/yr/unit area'i
Strip #
2
3
4
Type
Embankmf
Paved
Paved
Infiltration
Rate
D.I 173 >
0.1173
D.1 173
Source
User Entry
User Entry
User Entry
1 inn.c:^(» ,
Default
Select 1
Select
Select
Cl^l 1
Runoff
Rate
0.6020
0.6020
0.6020
-
Click "Select" in the desired row to select from pre-defined infiltration rates, or enter the desired value in the
iriiiirjiion rate column.
Recharge Rate (m/yr)
All Scenarios
Ditch Precip/Evap
Precip and Evaporation in Ditches
>
Ditch
Strip
1
9
Precipitation
Rate (m/yr]
.8763
.6763
Evaporation
Rate (m/yr)
.565
.565
^a
Rates are m/yr/unit area
« Previous
Figure 3-19. Input: Infiltration (9) for Roadways.
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IWEM User's Guide Running the IWEM Software
The features identified in Figure 3-19 are explained in more detail in the following paragraphs:
A. Choose Soil Type. Specify the soil type and geographic location of the roadway so that
the model can generate a recharge rate for your site. First, select the appropriate soil type
from the choices shown in the |SOIL DATA| dialog box:
- Coarse-grained soil (sandy loam)
- Medium-grained soil (silt loam)
- Fine-grained soil (silty clay loam)
- Unknown soil type.
If you choose one of the three default soil types (coarse, medium, or fine), the Monte
Carlo process will randomly assign values for the required soil-related input parameters
according to probability distributions that are appropriate for the specified soil type. If you
choose "unknown soil type" (the default selection), the Monte Carlo process will
randomly select one of the three possible soil types in accordance with their nationwide
frequency of occurrence. For more details, please see Section 6.5.2 of the IWEM
Technical Background Document.
B. Choose Climate Center. Infiltration and recharge rates for representative regions and
locations, or "climate centers," around the country have been calculated based on
meteorological data and soil type. By choosing the climate center that is representative of
the modeled site, you can use the infiltration and recharge rate(s) for this climate center as
an estimate of the rate(s) expected at your site. In many cases, selecting the climate center
that is closest to your site will provide the best estimate of infiltration rate. A map of the
IWEM climate centers is presented in Figure 4-9 of Section 4.3.2 of this document. You
should, however, verify that the overall climate conditions at the selected climate station
are representative of your site. Section 6.4 of the IWEM Technical Background Document
provides a detailed discussion of how the infiltration rates were developed.
To choose a climate center, click on the |ViEW CITIES LIST| button. The dialog box shown
earlier in Figure 3-18 will appear. See the bullets with that figure for instructions on
navigating that box.
C. View Recharge Rate. Once you have selected a soil type and the appropriate climate
center, the model will estimate the recharge rate for your site. The resulting value is listed
in the table at the center right of the Infiltration (9) screen.
D. Enter Infiltration Rate(s). The roadway module requires the rate of water infiltration
through each strip defined in your roadway. If you have estimates of these rates, then you
may enter those values here, along with any supporting information in the next column to
the right.
E. Select From Default Rates. If you do not have estimates of infiltration rates, you can use
one of the available default roadway infiltration rates. Click on the "Select" button to
display the dialog box shown in Figure 3-20.
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IWEMUser's Guide
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Roadway Strip Infiltration
Select the infiltration characteristics for Strip 1
Surface type: |Asphaltic Concrete (AC)
|~~ Select high range value (.32079 m/yr)
Select low range value (.05098 m/yr)
OK
Cancel
Figure 3-20. Default roadway strip infiltration dialog.
El. Current Strip Number and Type. The dialog box for selecting one of IWEM's
default roadway infiltration rates indicates that which strip and strip type is currently
selected.
E2. Choose Precipitation Basis for Infiltration Rate. Use the top drop-down list to
choose one of three possible options for representative climate data for your site:
- Use regional value based on min rainfall
- Use regional value based on max rainfall
- Use interpolated value based on climate center rainfall.
Each IWEM climate center is associated with representative climate centers for
minimum and maximum precipitation rates. You have the option of choosing either
the minimum or maximum representative climate center, or to interpolate the
infiltration rate based on the precipitation rates for the specific climate center you
chose in Item B. The infiltration rates displayed in the lower half of the dialog are
updated according to your choice.
E3. Choose Appropriate Surface Type. Use this drop-down list to choose an
appropriate surface type for the current strip:
- Asphaltic concrete (AC)
- Embankment
- Median paved with AC
- Median paved with portland cement concrete (PCC)
- Median unpaved
- Portland cement concrete
- Shoulder paved with AC
- Shoulder paved with PCC
- Shoulder unpaved
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IWEM User's Guide Running the IWEM Software
The infiltration rates displayed in the lower half of the dialog box are updated
according to your choice.
E4. Select High or Low Range Value. Select between infiltration rates that
corresponds to ensembles of material property assumptions that result in an upper-
bound value or lower-bound value for infiltration. Refer to Appendix E of the
IWEM Technical Background Document for more details on material property
assumptions.
F. Enter Runoff rates. If a ditch is defined, a runoff rate is required for each non-ditch
strip.
G. Enter Precipitation and Evaporation Rates. If a ditch is defined, precipitation and
evaporation rates are also required.
3.4.4.4 Probabilistic Screening Module
The EPACMTP model used in IWEM to simulate ground water fate and transport incorporates
certain constraints to ensure that the parameter values that are selected in the Monte Carlo
process will represent physically realistic WMU or roadway settings. These constraints are as
follows:
1. The base of a landfill, structural fill or waste pile must be above the water table, or the
elevation of ponded water in a surface impoundment must be higher than the water table
elevation. Land application units and roadways must be built on grade, so this constraint
is not necessary.
2. Infiltration- and recharge-induced mounding of the water table cannot rise above the
ground surface.
If either of these constraints is violated, EPACMTP will not run. Given the range of parameter
values that may be generated in the Monte Carlo process, in combination with user-specified site-
specific values, it is possible that IWEM might encounter a scenario where a constraint is
frequently violated and IWEM is therefore unable to complete the Monte Carlo simulation
process.
To prevent that occurrence, IWEM screens your input values and parameter
distributions prior to performing the EPACMTP Monte Carlo simulation to ensure
that an adequate number of Monte Carlo realizations can be conducted, based on the Sec 5 2
number of simulations selected.2 The Probabilistic Screening module of IWEM examines your
inputs to determine if you have provided complete and valid information. If you specify a
constant value for every parameter on screens 7 through 9 (i.e., Source Parameters (7), Location
of Well with Respect to Roadway (7a), Subsurface Parameters (8), and Infiltration (9) screens),
the screener routine will determine the magnitude of water table mounding (that is, IWEM will
evaluate the constraints on hydraulic connections between the source type and the water table). If
the screening is successful, suggesting sufficient Monte Carlo realizations can be conducted,
IWEM will take you to the next input screen, Constituent List (10); otherwise, a message box
will alert you to the most violated constraint and suggest potential remedies. If all proposed
2 IWEM defaults to 10,000 realizations. The user can change this value, but the Agency cautions that significantly
fewer iterations will impact the repeatability of the results.
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IWEM User's Guide Running the IWEM Software
remedies are inconsistent with site conditions, then IWEM is not appropriate for your site and a
detailed site-specific analysis should be considered.
If you do not provide site-specific values for all possible inputs, the screener will generate values
for the missing input parameters according to their appropriate distributions, and then evaluate
the constraints. The screening process is usually very fast, unless it has trouble generating
successful parameter sets. In that case, it could take as long as 2 minutes to complete. A progress
bar is updated during the screening process.
As part of the screening process, IWEM will check that the aquifer that will be modeled has a
sufficiently high transmissivity to supply enough water to a domestic drinking water well. A low
transmissivity value corresponds to a combination of a low hydraulic conductivity in the
saturated zone and a small saturated thickness. If this situation is encountered, IWEM will
display a warning message dialog box that says "IWEM had determined that the aquifer system
you have described is not likely to support a drinking water well. If this is inconsistent with your
site conditions, you may wish to increase the value of aquifer thickness or aquifer hydraulic
conductivity. If either of those changes are inappropriate for your site, you may still proceed with
the analysis. Do you wish to proceed with this analysis?" If you click |YES|, IWEM will continue
with the input parameters you provided; if you click |No|, it will return you to the input screens to
make changes.
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3.4.5 Input: Constituent List (Screen 10)
This screen is where you select the constituents that are present in the waste, and enter their
leachate concentration. Selection is the same for all source types, but leachate concentration entry
for roadways differs from that for WMUs and structural fills, so the sections below cover
choosing constituents (Section 3.4.5.1), entering leachate concentrations for WMUs and
structural fills (Section 3.4.5.2), entering leachate concentrations for roadways (Section 3.4.5.3),
and adding new constituents (Section 3.4.5.4)
3.4.5.1 Choose Constituents
You can choose to include in your analysis any of the 206 organic chemicals and 22 metal (25 for
the roadway module) constituents included in the IWEM database (see Appendix A for a
complete list), or you can also add constituents to the IWEM list. See Section 3.4.5.4 for how to
add constituents. Once you have added a constituent, you can select it like any other constituent
on this screen.
Figure 3-21 shows the Constituent List screen (10) highlighting features relevant to selecting
constituents.
Subsurface H^rameters
Constituent Name:! \
Number:
Constituent Name
CAS Number
B 3-32-9 AceYiapnthene
75-07-0 Acelaldehyde [Ethanal]
67-64-1 Acetone (2-propanone)
75-05-8 Acetomtnle (methyl cyanide)
98-86-2 Acetophenone
107-02-8 Acrolein
79-06-1 Acrylamide
79-10-7 Acrylic acid [prapenoic acidj
107-13-1 Aciylonitrile
309-00-2 Aldrin
107-18-6 Ally! alcoho
G2-53-3 Aniline (benzeneamine)
120-12-7 Anthracene
7410-36-0 Antimony
22569-72-8 Arsenic
15581-01-0 Arsenic (VI
7410-39-3 Barium
56-55-3 Ben:{a}anthrecene
71-43-2 Benzene
92-87-5 Benzidine
50-32-8 Benzo{a}pyrene
205-99-2 Benzo{b}fluoranthene
100-51-6 Benzyl alcohol
100-41-7 Benzyl chloride
7440-11-7 Beryllium
111-44-4 Bis(2-ch!oroethyl)ether
Leachate
Concentration
(mg/L)
Aniline (benzeneamine)
Figure 3-21. Input: Constituent List (10): Select Constituents.
The features identified in Figure 3-21 are explained in more detail in the following paragraphs.
The list box on the left side of the screen contains all constituents in the IWEM database
(including chemicals added by the user). This list will be referred below as the "Constituent list."
A. Search for Constituents by Name or CAS #. Type the name or the CAS number in the
[SEARCH BY| window to locate a particular constituent on the Constituent list. As soon as
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IWEM User's Guide Running the IWEM Software
you have typed in enough information to identify the constituent, it will be highlighted in
the Constituent list. You can then use the |ARROW| keys on the keyboard to move up or
down in the list if the highlighted constituent is not exactly the one you intended to select.
B. Sort the Constituent List. You can sort the constituents by name or by CAS number by
clicking one of the |SORT BY| radio buttons. By default, the list is sorted by name.
Regardless of sort order, the list is always displayed with the CAS number first, followed
by the name.
C. Filter the Constituent List. You can choose to display only organic constituents, or only
metals, or a combined list of all constituents by clicking one of the radio buttons under
ITYPE OF CONSTITUENT]. By default, all constituents are displayed.
D. Select Constituents to be Included in the Analysis. You can select constituents by
using one of the methods below:
- To select an individual constituent, click on its
name.
Navigating the List of Waste
Constituents:
Use the scroll bar at the right
of the display window
Use the |ARROW| keys on the
keyboard (once one
constituent in the list is
selected)
Type in the constituent name
- To select multiple constituents that are listed in
contiguous order (that is, one after another without
any non-selected constituents in the middle), click
on the first waste constituent, press down the |SHIFT|
key, and then click on the last waste constituent. All
waste constituents listed between the first and last
chosen constituents should now be highlighted. \c<-*0~.. DVi K~ /^0 -^^ D\
IOLAKUH DY| DOX (see nem o)
- To select multiple constituents that are not
contiguous, click on the first waste constituent, and then hold down the |CTRL| key
while selecting additional constituents using the mouse.
E. Add Highlighted Constituent(s) to the [SELECTED CONSTITUENTS] List. Once the appropriate
constituents are highlighted in the Constituent list (on the left of the screen), click on the
|ADD| (jH) button in the center of the screen to add it to your list of leachate constituents
(on the right side of the screen; see item F). Note that a waste constituent can also be
added directly to your list by double-clicking on it in the list on the left. Note that for
roadways, there are multiple tabs and subtabs in the selected constituents area, for each of
different roadway components (strips, ditches, drains). When you add constituents, they
are added to all components; you can specify a zero leachate concentration later for
constituents in specific roadway components if that roadway component does not use re-
used materials or if you do not anticipate those constituents to occur in the materials used
in that roadway component. See Section 3.4.5.4 for more on entering leachate
concentrations for roadway sources.
F. View List of Constituents to be Included in Analysis. Once you have successfully
added a constituent to your analysis, that constituent's name and CAS number will appear
in the |SELECTED CONSTITUENTS] window on the right side of the screen. If any of the selected
waste constituents hydrolyze into toxic daughter products, the daughter products are also
automatically added to the evaluation. You can modify constituent properties and toxicity
standards of the daughter product(s) in the upcoming screens.
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G. Select an Included Constituent. If you change your mind about a constituent you have
added, you can select and remove it. To select it, highlight the row showing the
constituent in the |SELECTED CONSTITUENTS| window on the right side of the screen by
clicking on the gray area to the left of the constituent CAS number. This may or may not
have a small right-pointing arrow in it.
H. Remove Selected Constituent from (SELECTED CONSTITUENTSI List. Click on the |REMOVE|
C^j) button to delete the highlighted constituent from your list of selected constituents.
For roadways, as with adding a constituent, removing a constituent removes it from all
roadway components.
3.4.5.2 Enter Leachate Concentrations for WMUs and Structural Fills
Figure 3-22 shows the Constituent List screen (10) highlighting features relevant to entering
leachate concentrations for WMUs and structural fills. The screen shown is for structural fills;
the one for WMUs is the same except that it omits the field for total teachable concentration,
which is not relevant to WMUs - the duration of leaching is a function of operational life.
jffl Input
Subsurface Parameters (8) | Infiltration (9
0 h R
w oarcn uy
Constituent Name:!
All Constituents
1 06-39-8 Epichlorohydrin A
1 06-88-7 Epoxybulene 1,2-
1 1 0-80-5 Ethoxyethanol 2- . .
1 11-1 5-9 Ethow/ethanol acetate 2- — ^
141-78-6 Ethyl acetate ' '
60-29-7 Ethyl ether ^ \
100-41-4 Ethylbenzene
106-93-4 Ethylene dibromide (1,2-Dibro mo ethane)
107-21-1 Ethylene glycol
75-21-8 Ethylene oxide
96-45-7 EthylenethiOLirea
206-44-0 Fluoranthene
16984-48-8 Fluoride
64-1 8-6 Formic acid
98-01-1 Furfural
31 9-85-7 HCH beta-
58-89-9 HCH (Lindane) gamma-
31 9-84-6 HCH alpha-
76-44-8 Heptachlor
1 024-57-3 Heptachlor epoxide
87-68-3 Hexachloro-1,3-butadiene
118-74-1 H exach I oro benzene
77-47-4 Hexachlorocyclopentadiene
« Previous
LH_|' & l| S3
Constituent List (1 0) Constituent Properties (1 1 )
c, R T f r
" * I >pc ot uon Jituent
-------
IWEM User's Guide Running the IWEM Software
leachate concentration of the parent constituent, the daughter product leachate
concentrations are not IWEM inputs.
B. Enter Expected Total Leachable Material Concentration(s). For structural fills, you
must also enter your expected total teachable material concentration in mg/kg for each
waste constituent. Consult Chapter 2—Characterizing Waste in the Guide for Industrial
Waste Management (U.S. EPA, 2002c) for analytical procedures that can be used to
determine expected teachable materials concentrations for waste constituents. In addition,
the user can also refer to the EPA's SW-846 web site (http://www.epa.gov/epawaste/
hazard/testmethods/sw846/new_meth.htm) to find newer validated methods to generate
leachate data for industrial materials. Section 6.2.2 of the IWEM Technical Background
Document provides additional guidance in determining or estimating appropriate input
teachable materials concentration values specifically for industrial materials used in
structural fills.
When both the leachate and total teachable concentrations are entered for a structural fill,
EPACMTP will automatically calculate the time required to deplete the selected constituent from
the fill.
The evaluation cannot be performed until both the expected leachate concentration and total
leachable concentration are provided for a structural fill (or the expected leachate concentration for a
WMU) for each selected waste constituent.
If you enter an expected leachate concentration that exceeds the solubility of that constituent,
IWEM will display a warning similar to this: "The leachate concentration specified for
[constituent] is greater than the cited solubility value in the database of [value] mg/L. Do you
want to change the leachate concentration?" If you accidentally entered the wrong value, click the
|YES| button and correct the expected leachate concentration. If you want to proceed with the
evaluation using your entered value, click the| No| button. In this case, a similar warning message
about your input leachate concentration will be included in the printed report.
3.4.5.3 Enter Leachate Concentrations for Roadways
Figure 3-23 shows the leachate concentration portion of the Constituent List screen (10)
highlighting features relevant to entering leachate concentrations for roadways.
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IWEMUser's Guide
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n(9)
Constituent List (10)
•:• Constituent Name
E
T CAS Number
i
i
(
Constituent Properties (11)
Type of Constituent
• All constituents
Orgenics
~ Metals
/ m
i
rips
f (6) Paved Area
(1)Dilch
1 ' Ditches 7 W\
1 (?) Paved Area (B) Shoulder
] (2) Embankment (3) Paved Area
/"
(9) Ditch
(A) Paved Area
Drains
IB
1^
(5) Median
y^
Constituent Initial Concentrations /
\
Chemicals
CAS Number
22S69-72-8
67-61-1
Constituent Name
Arsenic (III)
Acetone (2-propanone)
Layer 1 -Subgrade
Leachate Total
(mg/L) (mg/kg)
1 0.05
Layer 2 - Base
Leachate (mg/L
1 /
/
0
Total (mg/kg)
0.05
/
0
Layer 3- Pavement
Leachate
(mg/L)
Total (mg/kg)
,
Figure 3-23. Input: Constituent List (10): Enter Leachate Concentrations for Roadway Strips.
A. Select the Roadway Feature Group to Work on. The entry of constituent
concentrations is grouped by roadway |STRIPS|, |DiTCHES| and |DRAINS|. If no ditches are
defined, the |DiTCHES| tab and |DRAINS| tab are disabled. If at least one ditch is included but
no drains are defined, only the |DRAINS| tab is disabled. The strip tab is shown in Figure 3-
23, but the ditch and drain tabs are similar.
B. Select the Roadway Strip, Ditch, or Drain to Assign Constituent Concentrations.
Select the correct roadway-source strip, ditch, or drain to assign constituent leachate and
total teachable material concentrations by clicking on the corresponding tab.
Some items to keep in mind:
- Roadway strips are numbered consecutively, beginning with the strip closest to the
receptor well location.
- IWEM requires that at least one material layer in any one roadway-strip must contain
both leachate and total teachable material concentrations. However, you can leave
leachate concentration blank for some constituents in each strip and layer.
C. View the Different Layers of the Strip. This applies only to strips, as ditches are limited
to one layer and drains do not have layers. Layers are listed horizontally, and reflect the
number of layers you specified for the selected strip. You may have to use a scroll bar at
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the bottom of the window to view all layers, depending on the number of layers and your
screen settings. The scroll bar will appear if needed.
D. Enter Expected Leachate Concentration(s). For strips and ditches, you must enter your
expected leachate concentration in mg/L for each waste constituent for each layer that
contains constituents. The leachate concentration value cannot exceed 1,000 mg/L.
However, it can be zero for some layers, if no teachable materials were used in that layer.
Consult Chapter 2—Characterizing Waste in the Guide for Industrial Waste Management
(U.S. EPA, 2002c) for analytical procedures that can be used to determine expected
leachate concentrations for waste constituents. Section 6.3.9 of the IWEM Technical
Background Document provides additional guidance in determining or estimating
appropriate input leachate concentration values specifically for industrial materials used
in roadways.
Because the expected leachate concentrations of daughter products are controlled by the
leachate concentration of the parent constituent, the daughter product leachate
concentrations are not IWEM inputs.
For drains, instead of leachate concentration, you will enter an optional concentration of
water flowing into the upstream end of ditch. IWEM can accommodate pre-existing ditch
flows that have initial dissolved concentrations of constituents of concern. The presence
of constituents in existing ditch flows can have an impact on ground water concentrations
down-gradient of the roadway and should not be ignored.
E. Enter Expected Total Leachable Material Concentration(s). For strips and ditches,
you must enter your expected total teachable material concentration in mg/kg for each
waste constituent for each layer that contains constituents. This concentration can be zero
for some layers, if no teachable materials were used in that layer. Consult Chapter 2—
Characterizing Waste in the Guide for Industrial Waste Management (U.S. EPA, 2002c)
for analytical procedures that can be used to determine expected teachable materials
concentrations for waste constituents. Section 6.3.9 of the IWEM Technical Background
Document provides additional guidance in determining or estimating appropriate input
teachable materials concentration values specifically for industrial materials used in
roadways.
When both the leachate and total teachable concentrations are entered for a given layer, IWEM
will automatically calculate the time required to deplete the selected constituent from that layer
of the roadway.
The evaluation cannot be performed until both the expected leachate concentration and total
leachable concentration are provided for at least one layer in any roadway strip for each selected
waste constituent. As long as this requirement is met, any incomplete entries will be reverted to
blanks when the Constituent List (10) screen is left.
If you enter an expected leachate concentration that exceeds the solubility of that constituent,
IWEM will display a warning similar to this: "The leachate concentration specified for
[constituent] is greater than the cited solubility value in the database of [value] mg/L. Do you
want to change the leachate concentration?" If you accidentally entered the wrong value, click the
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|YES| button and correct the expected leachate concentration. If you want to proceed with the
evaluation using your entered value, click the| No| button. In this case, a similar warning message
about your input leachate concentration will be included in the printed report.
3.4.5.4 Adding New Constituents
To add a new waste constituent, click on the |ADD NEWCONSTITUENTS| button at the bottom of the
Constituent List (10) screen, as shown below:
92-87-5 Benzidine
50-32-8 Benzo{a}pyrene
205-99-2 Benzo{b}fluoran1hene
100-51-6 Benzyl alcohol
100-44-7 Benzyl chloride
7440-41 -7 Beryllium
-44-4 Bis(2-chloroethyljether
Add New Constituent
/
« Previous
Next»
The message box shown below in Figure 3-24 will appear:
" Enter New Constituent Data (10a)
CAS Number
Constituent Name
Cancel
QK
Figure 3-24. Input: Enter New Constituent Data (10a).
The features identified in Figure 3-24 are explained in more detail in the following paragraphs.
A. Enter CAS Number. The CAS number of a new constituent must be entered and it must
be a number that is not already in use by one of the IWEM constituents. If a CAS number
is not available or you do not know the number for a new constituent, any number can be
used here, as long as it is a unique number between 50,000 and 999,999,999.
B. Enter Constituent Name. The constituent name must be entered and it must be a name
that is not already in use by one of the constituents in the IWEM database.
C. Click to Enter New Constituent Data. After you click |OK|, a new entry in the database
will be created for your new constituent, and screen 20b (Figure 3-25) will appear.
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CarnbndgeSott Corporation. 2001 ChemFinder.com database and internet searching.
IJSEFA 1 'ii'DJie Err..'ironrncnial Fate 'I o n sta nf: tor Crqasnic -"he mica It Undc'i Consideration
USEPA. 19'j7a. Health Effects Assessment Summary Tables (HEAST). EPA-54Q-P.-97-Q36.
USEPA 199i:id. Evaluation of the Potential Carcinogenicity of Ethyl Methane sulfnnate
USEPA. 198Ea. Addendum to the Health Assessment DocumentiorTetrachloroethylene
Property
Cancel
Figure 3-25. Input: New Constituent Data (10b).
The features identified in Figure 3-25 are explained in more detail in the following paragraphs.
A. Enter Available Data for Constituent Properties. You can provide the following
constituent physical-chemical data as optional inputs. In addition, you can provide a
"User-defined RGC" or HBN later on, in screen 12.
- Molecular weight
- Solubility
- Log Koc
- Acid-catalyzed hydrolysis rate constant
- Neutral hydrolysis rate constant
- Base-catalyzed hydrolysis rate constant
- Diffusivity in air
- Diffusivity in water
- Henry's Law constant
- MCL (Maximum Contaminant Level)
If you do not enter a value for the physical-chemical parameters, a default value of zero
will be used for each of these parameters.
B. Select a Reference for Each Input Value. For each constituent property value that you
enter, you must specify the source of the data. Clicking in the |REFERENCE| field after
entering your data will display the drop-down list control w . Click on this control to
reveal a drop-down list of the current list of references in the IWEM database. You can
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choose one of these, or you can choose "New Source" to enter a new bibliographic
reference that is not included in the IWEM database, using screen lOc, shown in
Figure 3-26
j£|Add New Reference (lOc)
|±U hfeB Reference
Reference ^^J Extended Reference /^
^
rP
^
Cancel
v
Figure 3-26. Input: Add New Reference (10c).
Bl. Enter Brief Bibliographic Citation. Enter a brief bibliographic citation in this
field, in the form of "Author, Year." IWEM uses this information to index all
citations, and therefore, this entry must not duplicate an existing reference in the
IWEM database.
B2. Enter Complete Bibliographic Citation. Enter a complete bibliographic citation in
this field. You can use the existing references in the IWEM database as a guide for
formatting your newly added citation.
B3. Add Reference and Go Back to Add New Constituent (lOb) screen. Click the
|ADD NEW REFERENCE! button to enter this citation into the IWEM database and return
to dialog box lOb.
B4. Cancel and Go Back to Add New Constituent (lOb) screen. Click the |CANCEL|
button if you do not wish to use the new bibliographic citation. This will return you
to dialog box lOb.
C. Add New Constituent to the Database and Return to the Constituent List (10)
Screen. After entering the available data and selecting or entering a reference for each
value, click the |ADD| button to update the list of IWEM constituents. Once you have done
this, a message box will appear asking if you want to include this newly added constituent
in your analysis. Even if you decide not to use the new constituent in your current
analysis, the new constituent will be permanently added to the IWEM database.
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3.4.6 Input: Constituent Properties (Screen 11)
On the Constituent Properties (11) screen (Figure 3-27), you can modify constituent sorption and
degradation parameters. For each selected waste constituent, IWEM will display default values
that are stored in its database. These values will be used in the analysis, unless you override them
with user-supplied values. For all constituents, you can enter a value for the soil-water partition
coefficient (Kd). For organic constituents, you can also enter an overall first-order degradation
rate.
Constituent List (1D)
Constituent Properties (11)
Reference GW Cone (12)
Select a constituent from the first list below. PropeJ^es of the selected constituent will be displayed in the grids. To seethe properties of a daughter product select it from the second list
Waste Constituents; 1
IUse CCR Minteq isotherms
Waste Type: I _j Leachate pH; I
Properties shown above will be used in the model UNLESS you specify values forthe properties
in the grid on the right
If you enter values in this grid, they will be used in the model instead of the values shown in the grid
to the left. Data sources are required.
Clear Entry
« Previous
Next»
Figure 3-27. Input: Constituent Properties (11).
The features identified in Figure 3-27 are explained in more detail in the following paragraphs.
A. Choose Constituent to View. Select a constituent and/or daughter product from the
drop-down lists at the top of the screen. To view the properties for a waste constituent,
click on the drop-down list control w the right edge of the | WASTE CONSTITUENTS| list box.
To view the constituent properties for a constituent that is produced by hydrolysis of one
of your entered constituents, click on the drop-down list control w at the right edge of the
[DAUGHTER PRODUCTS! list box. If the [DAUGHTER PRODUCTS! box is blank or not present, it
means that the currently displayed waste constituent has no hydrolysis daughter products.
Then, use the mouse or the |ARROW| keys to scroll through the list of constituents until the
desired constituent is highlighted. Left click on the mouse or hit the |El\lTER| key to make
your selection.
B. Use CCR [Coal Combustion Residual] Sorption Isotherms. For roadways only, if the
current constituent is a metal for which a CCR-specific MINTEQA2 non-linear sorption
isotherm is available, this set of inputs (shown in Figure 3-27 in a blue box, which is not
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part of the screen) will be enabled. If the material of interest contains CCR and you would
like to use the waste-specific sorption data, make the following selections or entries:
- Check the Use CCR MINTEQ Isotherms checkbox
- Select CCR Waste Type. IWEM provides MINTEQA2 non-linear sorption
isotherms for 25 metals across four generic CCR waste types. The waste types are:
ash, ash & coal, flue gas desulfurization (FGD), and fluidized bed combustion (FBC)
wastes. If the material of interest contains CCR and you would like to use the waste-
specific sorption data, select a generic waste type that best represents your source
material of interest.
- Enter Waste-Specific Value for leachate pH. In addition to selecting a CCR waste
type, you must also provide a value for the pH of the leachate. Leachate pH is used to
select appropriate MINTEQA2 sorption isotherms for your constituent and
environmental conditions.
C. View Default Values and References. The constituent properties and their default
values and references for the selected waste constituent are listed in the table on the left
side of the screen. The screen shot in Figure 3-27 is for a metal; for an organic, this box
would also show hydrolysis rates (acid catalyzed, neutral, and base-catalyzed).
D. Enter Site-Specific or Updated Values and References. For each constituent, IWEM
assigns default values for Koc (Kd for metals) and hydrolysis rate constants (for organics
only) (see constituent list in Appendix A); however, you can enter and use site-specific
values for Kd (organics and metals) and overall decay rate (organics only) if these data are
available. To enter site-specific values, just type them into the table on the right side of
the screen. As noted, the screen shot in Figure 3-27 is for a metal; for an organic, fields
for the value and source of the overall decay rate would also be displayed below the fields
forKd.
By default, IWEM accounts for degradation from constituent hydrolysis only. IWEM
calculates the hydrolysis rate from constituent-specific values for the acid-catalyzed (ka),
neutral (kn) and base-catalyzed (kb) hydrolysis rate constants. Biodegradation can also be
an important process. However, biodegradation rates can vary greatly from site to site.
You should only increase the overall decay rate above the value corresponding to the
hydrolysis rate constants if there is clear evidence of biodegradation occurring at a site.
For organics, the calculation of the overall decay rate from the hydrolysis rate constants
and the calculation of Kd from Koc is given in Sections 6.6.1 and 6.6.2 of the IWEM
Technical Background Document.
For each input parameter for which you enter a site-specific value, remember to type in a
brief explanation of this value. This information is required and will be included in the
printed report.
E. Clear All Entries. Clicking this button will clear any user selections or data entry for the
current constituent.
Once your list of constituent properties is complete, click on the |NEXT| button to specify RGC
values to be used in the evaluation.
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3.4.7 Input: Reference Ground Water Concentrations (Screen 12)
In the Reference Ground Water Concentrations (12) screen (Figure 3-28), you select which
RGC is to be used to evaluate each waste constituent in the analysis. You can select an RGC (i.e.,
MCL) that is in the IWEM database, or you can supply a user-defined HBN or other RGC (e.g., a
state standard). The following options are available:
• Maximum Contaminant Level (MCL)
• User-supplied Health-Based Number (HBN)
• Other standard (this can be any value and is generally determined by your state regulatory
authority)
• Compare to all available standards.
Select a constituent from the grid then the desired standard from the list. Click the "Apply Standards" button to save each selection.
Related
Constituents
Constituent
22569-72-8 Arsenic (I
67-64-1 Acetone (2-propanone)
Standard
Standards for 22569-72-8 Arsenic (III)
Reference Ground Water
Concentration (mg/L)
101
Exposure The exposure duration represents the
Duration (yr) time period a person is assumed to
—7 ingest or inhale contaminated
groundwater corresponding to a
specific standard Press F1 for more
information.
Select Standard
» MCL
<" HBN-lnhalaiion Cancel
r HBN-Inhalation Non-Cancer
f HBN-li''
f* HBN-lngestion, Non-Cancer
C* MSN-Dem,al Cancel
<** HBN-Dermal Non-Cancer
r Other Standard
C Compare to all available standards
Select the desired standard tay clicking it?, radio button Click the "Apply Standards" button to save your selection.
3 q
Reference 1
I \
« Previous
Apply Slandard(s)
hJext»
Figure 3-28. Input: Reference Ground Water Concentrations (12).
The features identified in Figure 3-28 are explained in more detail in the following paragraphs
A. Select Constituent. On the row for the desired constituent, click in the cell on the far left
of the table to display a small arrow indicating which constituent is selected. Once a
constituent is selected, the available toxicity standards are displayed on the bottom half of
this screen. If you have selected a standard to apply for this constituent, it is shown next
to the constituent name. If not, that column will say "Not yet selected". Once a
constituent listed at the top of the screen is selected, the available ground water standards
(and RGC values) are displayed at the bottom. HBN rows are greyed out until you add
HBNs (see item B).
B. Add or Edit HBNs. If you wish to enter HBNs for the selected constituent, click on the
IEDIT HBNs| button. This will bring up screen 12a, shown in Figure 3-29. Here, you can
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enter HBNs for inhalation, ingestion, and dermal pathways, for cancer and non-cancer
endpoints.
G- EditHBNs(12a)
Reference Ground-water Exposure
Standard
HBN - Inhalation, Cancer
HBN - Inhalation, Non-Cancer
HBN - Ingestion, Cancer
HBN - Ingestion, Non-Cancer
HBN-Dermal, Cancer
HBN - Dermal, Non-Cancer
Exposure durations must be the same across an effect. All cancer durations
must have the same value and all non-cancer durations must have the same
value.
Figure 3-29. Input: Reference Ground Water Concentrations: Edit HBNs (12a).
Bl. Enter HBN. The HBN must be in mg/L. See Section 7 of the IWEM Technical
Background Document for guidance on obtaining HBNs.
B2. Enter Exposure Duration. Each HBN must have an exposure duration, which
corresponds to the time interval over which the average ground water concentration
is calculated. All cancer HBNs for a particular constituent must have the same
exposure duration, and all non-cancer HBNs must have the same exposure duration,
although the non-cancer exposure duration can be different from the cancer
exposure duration.
A note of clarification—the exposure duration does not control the time extent of a
flow and transport simulation. An EPACMTP simulation will continue for as long
as the receptor location is observing mass OR until the maximum simulation time is
reached (10,000 years). The exposure duration specifies the time window used to
compute the maximum time-averaged concentration.
B3. Enter Reference. You must enter a reference for each HBN-exposure duration pair
you enter.
B4. Return to RGC Screen (12). Click on the |SAVE| button to return to the main RGC
screen.
C. Enter Other Standard. If you wish to enter a state standard (e.g., one that is more
stringent than the MCL) or any other RGC, you can do it here. Consult with the
appropriate state regulatory agency for additional guidance on entering your own RGC
value.
D. Enter Exposure Duration for Other Standard. Consult with the appropriate state
regulatory agency for additional guidance on determining the exposure duration
associated with the RGC value.
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E. Enter a Reference for Other Standard. You must enter a reference for any Other
Standard you enter.
F. Select Standard(s) to Apply. Using the radio buttons, click on the appropriate standard
to use in your analysis. If a constituent has more than one standard, you should consult
with the appropriate state regulatory agency to determine which RGC should be used. If
none of the default choices are appropriate for your analysis, you can enter a new RGC
value and associated exposure duration (see items B through E above). Additionally, if
you choose the last option, [COMPARE TO ALL AVAILABLE STANDARDS], then the IWEM model will
use the most stringent standard to determine the recommendation.
F. Apply Selected Standard(s) to Selected Constituent. After you have chosen the
appropriate standard(s) for the selected constituent, click on the |APPLY STANDARDS] button to
input your choice. Once completed, your selection will be displayed in the |STANDARD|
column in the table at the top of the screen. Be sure you apply a standard for each
constituent.
3.4.8 Input: Input Summary (Screen 13)
The Input Summary (13) screen displays a summary of the input data for your analysis. You
cannot enter or edit data on this screen; rather, its purpose is to consolidate into one place all the
data you have already entered for the evaluation. If you notice that you have entered any data
incorrectly, use the |PREVious| button or click on the desired screen tab to go back to the
appropriate Input screen. This screen differs for WMUs/structural fills and roadways.
3.4.8.1 WMU and Structural Fill Input Summary
The input summary screen for WMU sources is shown in Figure 3-30 and has three sections
containing data on
• Constituent properties
Source and unsaturated zone
• Saturated zone.
Each section has a scroll bar which can be used to view information that does not fit on the
screen.
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l£] Input
Reference GW Cone (12)
Input Summary (13)
Constituent Properties
Constituent Name
Leach ate
Concentration
(mg/L)
Toxicity
Standard
RGC (mg/L)
Log(Koc)
(L/kg)
Ka
(/mol/yr)
Kn (/yt)
Kb
(/mol/yr)
Kd (L/kg)
Overall Decay
Coefficient (/yr)
Arsenic (III)
Aniline (benzeneamine)
Area (m~2):
Distance to well (m): 50
Depth to water table (m):
Soil type: SILT LOAM
nfiltration:
No Liner: .3256
Single Liner N/A
Composite Liner: N/A
Recharge Rate: 0.3256
4016.85
(not specified)
Aquifer thickness (m).
Regional hydtaulic gradient:
Aquifer hydraulic conductivity (m/yr):
Ground^jvater pH value (metals only):
Distance to well (m):
(not specified)
(not specified)
(not specified)
(not specified)
50
« Previous
Figure 3-30. Input: Input Summary (13): WMUs and Structural Fills.
The features identified in Figure 3-30 are explained in more detail in the following paragraphs.
A. Review Constituent Properties. For your reference, the constituent-specific properties
for each waste constituent in the analysis are displayed in the table at the top of the
screen. These include CAS number, name, expected leachate concentration, expected
total teachable materials concentration (structural fills only), the type and value of the
selected RGC, and fate parameters (log Koc, Kd, hydrolysis rate constants, and/or overall
decay rate). The entry in the "Related Constituents" column on the left side of the screen
indicates whether the constituent is present in the waste ("parent") or whether it is
included because it is a daughter product of a waste constituent ("daughter"). In the latter
case, the parent constituent is listed immediately above the daughter.
B. Review Source and Unsaturated Zone Inputs Note that this table has a scroll bar on
the right-hand side which can be used to view information that does not fit on the screen.
The information presented differs somewhat for WMUs and structural fills; the screen
shot shown in Figure 3-30 is for a WMU.
C. Review Saturated Zone Inputs. Note that this table has a scroll bar on the right-hand
side which can be used to view information which does not fit on the screen.
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3.4.8.2 Roadway Input Sum maty
The Input Summary (13) screen for Roadways is shown in Figure 3-31 and has six tabs
containing data on
• Roadway Geometry. Summary of general roadway configuration
• Strips. Summary of layer types and dimensions.
• Layers. Summary of layer material types, dimensions and properties
• Physical Characteristics of Ditches and Drains. Summary of ditch and drainage
configuration, layer properties and dimensions
• Climate and Subsurface Characteristics. Summary infiltration and runoff rates, soil
and subsurface properties and dimensions
• Constituents. Summary of constituents properties and distribution
Constituent List (10)
Constituent Properties (11)
Reference GW Cone. (12) |~
Input Summary (13)
(6) Constituents ~~ ~CM
^^B (5) Climate and S
ubsurface Characteristics
•M (4) Physical Characteristics ol Ditches and Drains ~ H
f"t— — (3) Layers ^^^
(SI (2) Strips |J
M^B (1) Roadway Geometry
Physical Configuration
gle between roadway and GW flow direction (-) 90
adway segment length (m) 120
stance between the roadway edqe and the monitoring well (m) 30.5
stance from roadway segment center to perpendicular well intercept line (rn) 0
mber of strips 9
mber of ditches 2
rnber of drains 2
« Previous
Next»
Figure 3-31. Input: Input Summary (13) - Roadways.
The features identified in Figure 3-31 are explained in more detail in the following paragraphs.
A. Summary of General Roadway Configuration. This table summarizes the data you
entered to characterize the general geometry of the roadway segment including: ground
water flow direction, roadway segment length, distance between the roadway edge and
the monitoring well, distance from roadway segment center to perpendicular well
intercept line, number of strips, number of ditches, and number of drains.
B. Summary of Strips and Dimensions. This table summarizes the data you provided
related to the roadway strip, including: strip type, width and number of layers.
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C. Summary of Layer Material Types, Dimensions and Properties. This table
summarizes the layer properties and dimensions related data provided by the user,
including: layer type, thickness, hydraulic conductivity and bulk density. Note that this
table has scroll bars on the bottom and right-hand sides, which can be used to view
information that does not fit on the screen.
D. Summary of Ditch and Drainage Configuration, Layer properties and Dimensions.
For your reference, the roadway-strips where the ditch receives overland flow from,
Manning's n coefficient, slope, maximum water depth, initial flow rate, runoff percent
not collected by the gutter, precipitation rate and evaporation rate are displayed in the
table on the top of the data grid by each ditch. Drain location, thickness, hydraulic
conductivity, bulk density and the percent of flow that reaches ditch are displayed on the
bottom of the data grid by each drain.
E. Summary Infiltration and Runoff Rates, Soil and Subsurface Properties and
Dimensions. This table provides summarized information related to soil type, aquifer
type, nearest climate center, recharge rate, infiltration rates and runoff rates for each non-
ditch strip. Note that this table has scroll bars on the bottom and right-hand sides, which
can be used to view information that does not fit on the screen.
F. Summary of Constituents and Properties. This table summarizes the constituents'
proprieties and their respective leachate concentrations provided to the EPACMTP
modeling. The information presented related to the constituents proprieties include, name
of the constituent, fate and transport parameters (log Koc, Kd, hydrolysis rate constants,
pH and overall decay rate), and value of the selected RGC. A section of this table also
presents user-specified leachate and total teachable material concentrations by roadway-
source strip and layer.
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3.5 Running an IWEM Evaluation: Run Manager (Screen 14)
After you have verified that all inputs are correct, click the |NEXT| button on the Input Summary
(13) screen to move to the Run Manager (14) screen (Figure 3-32).
Evaluation - Run Manager (14)
Number of Monte Carlo sir-nutations to run lor each constituent: ll 0000 -
EPACMTP Run Status lor Land Treatment Units
Constituent Name
Arsenic (III)
Aniline (taenzeneamme)
Constituent
Relationship
Run Req'd
Run Req'd
Single Liner
Composite
Liner
«Previous
Start EPACMTP
Figure 3-32. Evaluation: Run Manager (14).
The features identified in Figure 3-32 are explained in more detail in the following paragraphs.
A. Select Number of Iterations. Use the drop-down list to select a number of flow and
transport simulations to perform for each constituent present in roadway layers. Options
are 200; 500; 1,000; 5,000; and 10,000; the default is set to 10,000 iterations. You may
also type a value not available in the drop-down list. You may use any number of
iterations while building your model for the purposes of experimentation (fewer iterations
will run faster); however, it is highly recommended that you use 10,000 iterations
when conducting your final runs to minimize the uncertainty and increase the
confidence in the 90th percentile exposure estimate (see Section 5.2 of the IWEM
Technical Background Document). The number of iterations specified on this screen is
presented in the printable report available after the Monte Carlo simulations are complete.
B. Choose Additional Output Option. EPACMTP can generate addition output files that
contain the values of over 80 input parameters for each flow and transport iteration.
C. Launch EPACMTP Runs for Selected Set of Constituents. Click on the (START
EPACMTP| button to launch the required EPACMTP runs for the selected set of waste
constituents.
D. EPACMTP Run Status Summary. This summary table shows the current status of the
analysis. For each waste constituent, you can see whether the required modeling is in
progress or has been completed. In addition, this table will tell you whether the scenario
exceeds the benchmark (well concentration is greater than the RGC) or is below the
benchmark (well concentration is equal or less than RGC) for each constituent. The
image shown in Figure 3-32 is for a WMU run; a roadway run would display only one
results column, labeled Analysis Results.
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After you click on the |START EPACMTP| button, the ground water model is automatically executed
for each constituent for the WMU as a whole or, for a roadway source, each applicable roadway-
source strip and layer scenario, using the chosen constituent-specific and site-specific inputs. Any
toxic daughter products produced by hydrolysis of the selected constituents are also evaluated.
Each combination of constituent and layer scenario requires one probabilistic Monte Carlo
modeling run consisting of 10,000 model iteration. Assuming CPU speeds between 2.5-3 GHz, a
10,000-iteration Monte Carlo simulation of a single constituent released from a WMU or a single
roadway strip with a single layer will typically require 5 to 12 minutes. The simulation time
increases linearly with the number of constituents and the number of roadway strips and layers
containing teachable constituent mass. Therefore, IWEM includes a Run Manager dialog box
that displays the current status of your modeling analysis (see Figure 3-33); this way, you will
know that the model is working and how much progress has been made at any given point in
time. In addition, the EPACMTP dialog box displayed for each Monte Carlo run indicates which
strip and layer are being simulated.
k
Processing Input File 22569728_RW_UD_Strip_5.in
IWEM Version 3.1
Industrial Waste Management Evaluation Model
A Ground Water Pathway
Fate and Transport Analysis
Using EPACMTP VERSION 2.2
[EPA's Composite Model for Leachate
Migration with Transformation Products]
Simulating
ARSENIC3 *•*
Leaching From
A ROADWAY
Current Realization:
53 OF 100
'Elapsed Time: 00:00:03 (hh:mni:ss)
Estimated Time Remaining
For This Simulation: 00:00:03 (hh:mm:ss)
Running
Figure 3-33. Evaluation: EPACMTP dialog box displayed during model execution.
The features identified in Figure 3-33 are explained in more detail in the following paragraphs.
A. Constituent Currently Being Simulated. Constituents are run in alphabetical order,
regardless of the order in which you added them to your analysis.
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B. Source Being Simulated. This displays the source type (e.g., Landfill, Roadway). For
WMUs, it also displays the current liner scenario being simulated (No Liner, Clay Liner,
Composite Liner, or user-defined).
C. Running Indicator. This box displays "Running" to indicate that EPACMTP is running.
D. Input Filename to Track Simulation Progress. The currently executing EPACMTP
input filename is displayed at the top of each EPACMTP dialog box to help you monitor
the model's progress in real time. The filename is formatted in the following way:
[CASID#]_[Source Type]_[Liner]_[Strip #].in
Where:
[CASID#] = Unhyphenated CAS number of current constituent
[Source Type] = A 2 or 3 letter code for the type of source:
LAU = Land application unit
LF = Landfill
SI = Surface impoundment
WP = Waste pile
SF = Structural fill
RW = Roadway
[Liner] = A 2 to 4 letter code for the current liner:
NLin = No liner (WMUs and structural fills only)
CLin = Clay liner (WMUs only)
GM = Geomembrane (composite) liner (WMUs only)
UD = User-defined (used for roadways or for WMUs for which you specified
a site-specific infiltration rate)
[Strip #] = The roadway-source strip number assigned in the Source Parameters (7)
screen (e.g., Strip_l). This is displayed only for Roadway sources; for
WMUs and structural fills, it is omitted
For example, the filename 7440439_RW_UD_Strip_l.in indicates that the EPACMTP input file
represents cadmium (CAS 7440-43-9) released from strip 1 of the roadway. The file name
7440439_SI_CLin.in represents cadmium released from a surface impoundment with a clay liner.
The EPACMTP runs proceed from the first to the last selected constituent. For WMUs,
EPACMTP runs for a constituent are sequentially launched for the no-liner, single clay-liner, and
composite-liner scenarios until a scenario that does not exceed the RGC is found. That is, if the
single clay- liner scenario is determined to not exceed the RGC for a given constituent, the
composite-liner scenario for that constituent is not modeled. For the land application unit and
structural fills or user-defined liner/infiltration scenarios, only one liner scenario per constituent
is evaluated. For roadway sources, EPACMTP runs for each constituent are sequentially
launched for all strips and layers containing both leachate and total teachable material
concentrations.
When the run is complete, this box will close and you will return to the Run Manager (14)
screen. You will also be prompted to save your evaluation.
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3.6 IWEM Results
Once EPACMTP completes the fate and transport modeling, IWEM presents Summary Results
(Screen 15), Detailed Results (Screens 16-18), and an Evaluation Summary (Screen 19). These
are discussed in the following sections.
3.6.1 Summary Results (Screen 15)
The summary results present a liner recommendation for WMUs or an assessment of whether the
reuse of industrial materials in a structural fill or roadway design is appropriate. The result is
based on a comparison of the estimated 90th percentile ground water exposure concentrations
and the specified RGC. If the ground water exposure concentration of a constituent does not
exceed the specified RGC, then the liner scenario is considered protective for that constituent;
similarly, for a structural fill or a roadway scenario, the reuse of industrial material is considered
appropriate. If the ground water exposure concentration exceeds the specified RGC, then the
evaluated scenario is not protective (for liners) or inappropriate (for a roadway or a structural
fill).
Figure 3-34 shows the summary results screen.
S • Output Summary (15)
CAS Number
Constituent Name
Arsenic f|
Aniline [benieneammej
Minimum Liner Recommendation
Based on consideration of the toxicity standards of all listed constituents, the minimum liner recommended is:
No Liner /
« Previous
[Detailed Result'
ecomrnendation »
Figure 3-34. Output (Summary): Summary Results (15).
The features identified in Figure 3-34 are explained in more detail in the following paragraphs.
A. Recommendation for Each Constituent. For WMUs, this column is generally headed
"Minimum Liner Recommendation" and it will display the minimum recommended liner.
If you entered a site-specific infiltration rate, then the column is headed "User Defined
Infiltration" and it will display whether or not the modeled infiltration rate will result in a
ground water exposure concentration that is above or below the specified RGC. For
structural fills and roadways, this column is headed "Results" and it will display whether
or not the modeled structural fill or roadway design will result in a ground water exposure
concentration that is above or below the specified RGC.
The no-liner, single clay-liner, and composite-liner recommendations are displayed in
green text. If the composite liner exceeds the user-provided benchmark, then this message
is displayed in red text. If the liner recommendation is "Not Applicable," then this
message is displayed in black text. Structural fill and roadway results are displayed in
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green text if the ground water exposure concentration is below the RGC and in red text if
it is above.
B. Overall Recommendation. For WMUs, the bottom of the screen displays an overall liner
recommendation based on consideration of all waste constituents (and their daughter
products). If EPACMTP estimates that the 90th percentile values of ground water well
concentration for all constituents under the no-liner scenario are below their respective
RGCs, then IWEM will recommend that no liner is needed to protect ground water. If the
modeled ground water exposure concentration of any constituent under the no-liner
scenario is higher than its RGC, then at least a single clay liner is recommended (or in the
case of land application units, land application is not recommended) based on the inputs
and assumptions you provided. If the estimated ground water exposure concentration of
any constituent exceeds the RGC under the composite liner scenario, then consider
pollution prevention, treatment, and more protective liner designs, as well as consultation
among regulators, the public, and industry to ensure such wastes are protectively
managed. For waste streams with multiple constituents, the least stringent liner design
that is protective for all constituents is the overall recommended liner design.
This box is not shown for structural fills or roadways; for those, the design is only
deemed acceptable if the ground water exposure concentrations for all constituents are
below the specified RGCs.
C. Go to Detailed Results. Clicking on the (DETAILED RESULTS] button will take you to a
detailed listing of the results (Screens 16-18), including the constituent-specific modeling
results for all evaluated liner scenarios. See Section 3.6.2.
D. Go to Recommendations. Clicking on the |RECOMMENDATION| button will take you to the
Evaluation Summary (19) screen, where you can choose to view the report or save your
analysis and exit the IWEM software. See Section 3.6.3.
3.6.2 Output (Details) (Screens 16, 17, and 18)
The detailed results present the data upon which the evaluation is based, by constituent. The
expected leachate concentration is listed, along with the specified RGC type and value and the
resulting 90th percentile ground water exposure concentration calculated by EPACMTP. These
detailed results allow you to understand how the liner design recommendations were developed
or the overall appropriateness of reusing industrial materials in a structural fill or roadway were
determined.
If you directly enter a value for infiltration (for any of the four types of WMUs), EPACMTP will
use this value of the infiltration rate in its fate and transport simulation, and IWEM will then
compare the predicted ground water well concentration to each constituent's RGC. In this case,
the detailed results will consist of only one screen, labeled "Results -User-Defined Liner (18),"
rather than the three that are shown below in Figure 3-35. Also, only one screen is displayed for
roadways, labeled "Results - Roadway (18)."
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CAS Constituent Name
62-5 3- 3
Aniline (benzeneamine)
Leachate
Concentration
(mg/L)
LI LI I CO
Toxicity Standard
Exposure
Duration (y)
Reference
Groundwater
Concentration (mg/L)
0.01
90th Percentile
Exposure Level
(mg/L)
LI LI LlC I
Below
Benchmark?
30 . 0.0169 , 0.0014
0 ' a o o
« Previous
Nummary Results
Recommendation »
Figure 3-35. Output (Details): Results (16).
Also, for analysis of a land application unit or a structural fill, only the no-liner scenario is
evaluated, since engineered liners are not typically used at land application units or under
structural fills. In this case, the detailed results will consist of only one screen.
The features identified in Figures 3-35 are explained below.
A. Leachate Concentration. For WMUs and structural fills, the entered leachate
concentration for each constituent is displayed in the third column. This is the value that
was used by IWEM in the EPACMTP ground water fate and transport modeling. For
roadways, the maximum leachate concentration entered across the various material layers
containing a constituent is show here. This is NOT the value that was used by IWEM in
the EPACMTP ground water fate and transports modeling for ALL layers—the layer-
specific leachate concentrations entered on the Constituent List (10) screen were used in
the ground water fate and transport modeling.
B. Dilution and Attenuation Factor. This column shows the 90th percentile value of the
ground water dilution and attenuation factor (DAF) calculated by EPACMTP.
C. Toxicity Standard. The selected RGC type (or toxicity standard) is displayed in this
table for your reference. Options are MCL, HBN-Ingestion, HBN-Inhalation, HBN-
Dermal, and User-Defined.
D. Exposure Duration. The exposure duration associated with the RGC and used to
estimate the 90th percentile exposure level.
E. Selected RGC Value. The selected RGC value is also displayed in this table for your
reference.
F. Exposure Level (Ground Water Concentration). To determine whether or not the
modeled scenario is protective (for liners) or appropriate (for roads and structural fills) for
a given constituent, the estimated 90th percentile ground water exposure concentration is
compared with the specified RGC.
G. Is the Exposure Level Less than the RGC? The result of the comparison between the
modeled 90th percentile exposure level (ground water exposure concentration) and the
specified RGC is displayed at the far right of this table. If the 90th percentile exposure
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level does not exceed the specified RGC, then the evaluated scenario is protective for that
constituent given the RGC and the text in the last column of this table will read "Yes" for
that constituent. If the 90th percentile exposure level exceeds the specified RGC, then the
evaluated scenario is not protective for that constituent given the RGC and the text in the
last column of this table will read "No" for that constituent.
H. Go to Summary Results (15) Screen. Click on the (SUMMARY RESULTS] button to go back to
the Summary Results (15) screen.
I. Go to Evaluation Summary (19) Screen. Click on the |RECOMMENDATION| button to go to
the Evaluation Summary (19) screen, where you can choose to view the report or save
your analysis and exit the IWEM software.
3.6.3 Evaluation Summary (Screen 19)
The Evaluation Summary (19) screen (Figure 3-36) provides the minimum protective liner
design for WMUs, or reports the appropriateness of the beneficial reuse of industrial waste
material in structural fills or roads.
\ Evaluation Summary a B \j£
Evaluation Summary (19)
The results of the analysis recommend the following design: JK
No Liner
You may choose to print the results and exit this program. You may also return to the beginning of the evaluation, or you may conduct your own site-specific
assessment.
«Previous jl Report
Figure 3-36. Evaluation Summary (19).
The features identified in Figures 3-36 are explained in more detail in the following paragraphs.
A. Overall Evaluation Result. The liner recommendation (WMUs) or beneficial use
determination (roadways or structural fills) is displayed at the top of this screen.
• For landfills, surface impoundments, and waste piles that were modeled using a
location-specific estimate of the infiltration rate, the available recommendations are
- no-liner
- single clay-liner
- composite-liner
- exceeds a benchmark
• For land application units that were modeled using a location-specific estimate of the
infiltration rate, the available recommendations are
- no-liner
- exceeds a benchmark
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* For any WMU that was modeled using a user-specified site-specific value for the
infiltration rate, the available recommendations are
- below all benchmarks
- exceeds a benchmark
• For structural fills, the available results are
- below all benchmarks
- exceeds a benchmark
• For roadways, the available results are
- below all benchmarks
- exceeds a benchmark
For WMUs, if your evaluation results in a recommendation of "exceeds a benchmark,"
then the chosen liner design for managing the waste may not be appropriate at the
selected site. In this case, consider pollution prevention, treatment, and more protective
liner designs, as well as consultation among regulators, the public, and industry to ensure
such wastes are protectively managed. See Chapter 4 of the Guide (U.S. EPA, 2002a) for
further information.
For structural fills and roadways, if your evaluation results are "exceeds benchmark,"
then the amounts and/or characteristics of industrial material included in the structural fill
or roadway design may not be appropriate at the selected location. In this case, consider
reducing the amount of material included in a particular layer or fill, or consider
potentially eliminating the material altogether..
B. Display Reports. Clicking on the |REPORT| button displays the IWEM Report (examples
can be found in Appendices B and C for WMUs and Roadways, respectively). The report
functionality is a bit different for structural fills/roadways as compared to WMUs:
• Structural Fills/Roadways. When you click on the |REPORT| button for structural fills
or roadways, a printer setup dialog box will appear. Select your printer and click |OK|.
A preview of the report will be displayed. From there, you can navigate pages by
using (NEXT PAGE| and PREVIOUS PAGE|, select |PRINT|, or |Exu| the report. When you choose
to print the report, a Windows print dialog box appears, where you can adjust printer
settings or choose to print selected pages. You can save the report by printing it to a
PDF file.
• WMUs. When you click on the |REPORT| button for WMUs, a preview of the report
will be displayed. These reports were designed using legacy software that provides
different menu controls. Once the report is displayed on-screen, you can then use the
following toolbar buttons to print, save, and scroll through the pages of the report:
i| | Print the report. A Windows print dialog box appears, where you can adjust
™ printer settings or choose to print selected pages. Note: The WMU reports
can only be printed to your default system printer. To change printers, you
will need to change your default printer from the Windows Control Panel.
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Save (export) the report. A dialog box appears with several output file type
options; however, most of these are no longer supported. Success with the
export utility depends on what software you have installed on your PC. Most
users will find that the best option for saving a document-ready report is to
use the Print button (above) with a default printer set to a PDF driver.2
View the next page of the report
View the last page of the report.
View the previous page of the report
View the first page of the report.
100% Change the display size of the report.
IWEM Report Includes
Facility data entered on the Source Type (6) screen.
List of selected constituents and their corresponding leachable concentrations entered on the
Constituent List (10) screen.
List of input values and explanations of user-input data, as summarized on Input Summary (13)
screen.
Summary results for each selected constituent, based on the user-specified RGC for each
constituent.
Detailed results for each selected constituent, based on the user-specified RGC for each
constituent, and including an explanation of any appropriate caps or warnings about the presented
results.
Constituent properties and RGCs for each selected constituent, including full references for the
data sources.
3.6.4 Save and Exit
At this point, you may want to save your results if you did not do so after the run finished. Click
on the |FlLE| menu and choose |SAVE| or |SAVE As|. A dialog box will then open, which prompts you
for the filename and directory location, as appropriate. Once you have provided a filename, the
tool will save two files, automatically applying the "wem" and "mdb" extensions for you. The
combination of these two files completely describes the data you have entered and any model-
generated results. Click on the |SAVE| button on the toolbar. If you are editing a previously saved
evaluation, the file will be automatically updated. If you have created a new evaluation, the |SAVE
As| dialog box will open, as described above.
Note that IWEM will not allow you to save both model inputs and results at a point where the
inputs do not correspond to the model-generated results. If you do choose to save your work in a
situation like this, only the inputs will be saved; that is, when you open this file at a later date,
If you do not have a PDF driver installed on your computer, many free PDF drivers are available online.
Functionality varies; CutePDF has good functionality and has been tested with IWEM. You can
download it free from http://www.cutepdf.com/.
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you will have to perform an evaluation to create the corresponding results. Once you have
completed an evaluation, you should save it under an appropriate file name. If you want to start a
new evaluation by editing an existing IWEM file, you should first save the new evaluation under
a different name to avoid losing the results of your original evaluation.
To exit IWEM, click on the |FlLE| menu, and choosing |ExiT|. If you forget to save before trying to
exit, a dialog box will ask if you want to save your data before exiting the software.
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5. Understanding Your IWEM Results
After completing an analysis, IWEM provides a recommendation for a liner design for a WMU
or on the appropriateness of reusing industrial materials in a structural fill or roadway design. As
with all modeling, the recommendations should be taken with the consideration of the
assumptions underlying the model and the adequacy of the input data that the user provided. This
section provides guidance on how IWEM may assist you in answering the following questions:
• For WMUs,
- What kind of liner will be necessary to safely manage my waste in a landfill, surface
impoundment, or waste pile?
- Is land application appropriate for my waste?
• For structural fills and roadways,
- Is the beneficial reuse of industrial materials in a structural fill or roadway design
appropriate?
Should I consider a detailed site-specific assessment?
5.1 IWEM Recommendations for WMUs
IWEM makes recommendations for landfills, waste piles, and surface impoundments
by identifying the minimum liner design that is protective of ground water for all
waste constituents, based your inputs and the RGCs selected. For land application
units, IWEM determines whether land application of waste is considered appropriate (i.e., the
ground water exposure concentrations of all constituents do not exceed their respective RGCs).
IWEM uses the EPACMTP fate and transport model to estimate the ground water exposure
concentration that is expected for each waste constituent given the leachate concentration you
specified. IWEM uses the technique of Monte Carlo analysis to develop a probability distribution
of ground water well exposure concentrations for each constituent and liner scenario. IWEM uses
the 90th percentile of the estimated ground water well exposure concentrations to make liner
recommendations, or determine if a land application of waste is appropriate. IWEM arrives to
these conclusions by comparing the 90th percentile estimated ground water exposure
concentration to the RGC(s) for each constituent.
The Monte Carlo simulations required for an IWEM evaluation can be computationally
demanding, and an evaluation of multiple liner designs for a single waste constituent can take
several hours. In order to optimize the computational process, For all WMUs except land
application units, IWEM will first perform the liner scenario evaluations sequentially: from least
protective (no-liner) to most protective (composite liner) IWEM first makes this evaluation for
the no-liner scenario. If the estimated ground water exposure concentration is less than the
applicable RGC(s), then the no-liner scenario is protective of ground water for that constituent,
given the RGC you entered. IWEM evaluates all waste constituents in this manner. If the 90th
percentile ground water exposure concentrations of all waste constituents are below their
respective RGCs for the no-liner scenario, then IWEM recommends the no-liner scenario as
being protective, given the RGCs, and the evaluation is complete. However, if the ground water
exposure concentrations of one or more waste constituents exceed the RGC for the no-liner
scenario, then IWEM will evaluate, sequentially, the single clay liner scenario and, if necessary,
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the composite liner scenario to recommend the minimum liner design that is protective for all
constituents, given the RGCs.
After conducting an IWEM evaluation, you can choose to implement the recommendation by
designing the unit based on the liner recommendations given by the IWEM software, or you may
choose to continue to a detailed site-specific analysis. If you choose to implement the IWEM
recommendation, consultation with state authorities is recommended to ensure compliance with
state regulations, which may require more protective measures than the results recommend.
If after conducting an IWEM evaluation, you are not satisfied with the resulting recommendations
or if site-specific conditions seem likely to support the use of a liner design different from the one
recommended (or suggest a different conclusion regarding the appropriateness of land application
of a waste), then you may conduct a fully site-specific ground water fate and transport analysis.
5.2 IWEM Recommendations for Structural Fills and Roadways
TBD
IWEM makes recommendations for structural fills and roadways by determining
whether the reuse of industrial materials in a fill or roadway design you modeled is
appropriate, given the RGCs you entered. ^ec- ^
IWEM uses the EPACMTP fate and transport model to estimate the ground water
exposure concentration that is expected for each waste constituent given the fill or roadway
design and leachate and total concentrations you specified. IWEM uses the technique of Monte
Carlo analysis to develop a probability distribution of ground water well exposure concentrations
for the fill or each roadway strip containing teachable constituent mass. IWEM uses the 90th
percentile of the estimated ground water well exposure concentrations to determine if the
structural fill or roadway design is appropriate. If more than one roadway strip contains reused
materials with a teachable constituent, IWEM will sum up the 90th percentile ground water well
exposure concentrations for all strips leaching that constituent. IWEM compares the single or
aggregate 90th percentile ground water exposure concentration to the RGC(s) for each
constituent. If the estimated 90th percentile ground water exposure concentrations of all waste
constituents are below their respective RGCs, then IWEM determines that the reuse of industrial
materials in a structural fill or roadway design modeled is appropriate, given the RGCs. The
recommendations should be taken with the consideration of the assumptions underlying the
model and the adequacy of the input data that the user provided. The Agency also recommends
that the user consults with the appropriate agency to ensure that the recommendation comply
with state regulations.
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4. Understanding Your IWEM Input Values
This section of the User's Guide will assist you in understanding the source (WMU, structural
fill, and roadway), waste constituent, and other fate and transport data that IWEM uses to
evaluate the protectiveness of WMU liner design, as well as the appropriate reuse of industrial
materials in structural fill, or roadway design.
The IWEM Technical Background Document provides additional detail on the input values. To
assist you in cross-referencing the discussion on each input parameter to the corresponding
section(s) of the Technical Background Document, specific cross-references are
provided for each IWEM input. The cross-references are indicated pictorially as IjBD
shown at right. k=*fc=
Sec. x.y.z
4.1 Overview
This section provides a brief introduction to the general types of input parameters for which you
can provide site-specific values. Those input parameters that are easily measurable and important
to the model output are generally required inputs: you must provide site-specific values. The
remaining input parameters are optional: use of site-specific data is strongly recommended for
these parameters. However, if you do not have a value, the IWEM software will either allow you
to select a default value if one is available, or you may choose from tables of suggested values
that are representative of an array of site conditions or material properties. However, the more
site-specific values you use, the less uncertain the results will be.
There are some optional features available in the roadway source type (e.g., ditches, gutters,
embankments, and drains) that you may utilize in your conceptual roadway cross-section. There
are additional required input parameters that you will need to specify if you elect to include one
or more of these features in your analysis. The tables in this section give the allowable ranges and
defaults (where applicable) for inputs. Section 6 of the Technical Background Document
provides additional guidance in setting values in the absence of site-specific values.
4.1.1 Default Values for Missing Data
Default values are generally obtained from IWEM's internal ground water modeling and
constituent property databases. IWEM is designed to help you make reasonable choices for
default parameter values. For instance, if you do not know the specific values for ground water
parameters, such as the thickness of the saturated aquifer zone and the hydraulic ground water
gradient, but you do know the general hydrogeology of your site (e.g., you have an alluvial
aquifer at your site), IWEM will use this information to select appropriate ground water values
for alluvial aquifers. Depending on the parameter involved, IWEM may use either a single
default value for a missing parameter, or it may use a probability distribution of values, to
accommodate a range of possible values.
4.1.2 How IWEM Handles Infeasible User Input Parameters
IWEM checks all entered data values. It verifies that only numeric data are entered in data fields
and that values are non-negative. In addition, IWEM checks that values are all within feasible
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ranges. When a value is outside the feasible range, IWEM will display a warning and will not
allow you to proceed until you change the entered value.
In addition to checking individual parameters, IWEM ensures that combinations of parameters
will not lead to physically unrealistic results. This is particularly the case for parameter
combinations which could cause an excessive degree of ground water mounding underneath a
source. The extent of ground water mounding depends on source characteristics, the permeability
of the unsaturated and saturated zones of the aquifer, the depth to ground water and the saturated
thickness of the saturated zone. IWEM checks for infeasible parameter combinations after you
have entered all parameters and alerts you if it has found a problem. If IWEM determines that the
data you have provided will cause an excessive degree of ground water mounding, IWEM will
reduce the allowed infiltration rate.
The following sections provide detailed descriptions of the individual parameters, including how
you may obtain site-specific values. The parameters are organized in groups, according to the
grouping in the IWEM software data entry screens:
• Section 4.2: Source Parameters
- WMU Source Parameters
- Structural Fill Source Parameters
- Roadway Source Parameters
• Section 4.3: Fate and Transport Parameters
- Subsurface Parameters
- Hydrologic (Infiltration and Recharge) Parameters
• Section 4.4: Waste Constituents and Constituent Parameters
- Constituent Selection and Concentration
- Physical-Chemical Properties
- Reference Ground Water Concentrations
Note that parameter values must be entered in the units specified; a table of common conversions
is provided in the front matter to assist you.
4.2 Source Parameters
On the Source Type (6) screen, you will specify the type of source and information about the
facility (e.g., name, address). The Source Parameters (7) screen will vary significantly depending
on whether you selected a WMU source (landfill, waste pile, surface impoundment, or land
application unit), structural fill source, or a roadway source. Therefore, inputs for these different
source types are discussed separately in the following sections.
4.2.1 WMU Parameters
IWEM address four different types of WMUs. Each of the four unit types reflects
waste management practices that are likely to occur at industrial Subtitle D facilities.
The WMU can be a landfill, a waste pile, a surface impoundment, or a land ®ec ^1
application unit. The latter is also sometimes called a land treatment unit. Figure 4-1
presents schematic diagrams of the different types of WMU's modeled in IWEM.
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Cov«r
unsaiuralad zone
saturated zone
(A) LANDFILL
SURFACE IMPOUNDMENT
luralW ions
ICI WASTE PILE (D) LAND APPLICATION LIMIT
Figure 4-1. WMU types modeled in IWEM.
Landfill. Landfills are facilities for the final disposal of solid waste on land. IWEM
considers closed landfills with an earthen cover and either no-liner, a single clay liner, or
a composite, clay-geomembrane liner. IWEM assumes there is no leachate collection
system. The release of waste constituents into the soil and ground water underneath the
landfill is caused by dissolution and leaching of the constituents due to precipitation,
which percolates through the landfill. The type of liner that is present controls the amount
of leachate, which is released from the unit. Because the landfill is closed, the
concentration of the waste constituents will diminish with time due to depletion of
landfill wastes. The leachate concentration value that is used as an input is the expected
initial leachate concentration when the waste is 'fresh'.
Surface Impoundment. A surface impoundment is a WMU which is designed to hold
liquid waste or wastes containing free liquid. Surface impoundments may be either
ground level or below ground level flow-through units. They may be unlined, or they may
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have a single clay liner or a composite clay-geomembrane liner. Release of leachate is
driven by the ponding of water in the impoundment, which creates a hydraulic head
gradient across the barrier underneath the unit. You can enter a site-specific value for the
operational life or you can opt to use the default of 50 years, after which the release of
constituents in leachate ceases.
• Waste Pile. Waste piles are typically used as temporary storage or treatment units for
solid wastes. Due to their temporary nature, they will not typically be covered. IWEM
does consider liners, similar to landfills. You can provide a site-specific value for the
operational life or you can opt to use the default value of 20 years. After the operational
period, IWEM assumes the waste pile is removed and leaching of constituents to the
underlying soils stops.
• Land Application Unit. Land application units (or land treatment units) are areas of land
receiving regular applications of waste or some soil amendment, which can be either
tilled directly into the soil or in the case of a liquid waste, sprayed onto the soil and
subsequently tilled into the soil. IWEM models the leaching of wastes after they have
been tilled with soil. IWEM does not account for the losses from land application units
due to volatilization during or after waste application. You can enter a site-specific value
for operational life or you can opt to use the default value of 40 years. After the
operational life has elapsed, land application of wastes ceases, as does the leaching of
constituents in the waste. In the case of a waste that is applied on a regular basis and
rapidly migrates to the subsurface, the operational life can represent the period of time
during which a waste is applied. After that time, leaching ceases. The operational life for
land application units is discussed in detail below. Land application units are evaluated
for only the no-liner scenarios because liners are not typically used at this type of facility.
Table 4-1 provides a list of the IWEM WMU input parameters. The following sections discuss
the input parameters in more detail.
Table 4-1. IWEM Input Parameters: WMU
Parameter
Applicable
WMUs
Units
Default Value
If No User
Input
Allowable Range
Minimum
Maximum
Required Inputs
Area of the WMU
Depth of WMU
Ponding Depth
All
LF
SI
m2
m
m
NA
NA
NA
1
>0
0.01
1.0E+8
10
100
(continued)
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IWEMUser's Guide
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Parameter
Applicable
WMUs
Units
Default Value
If No User
Input
Allowable Range
Minimum
Maximum
Optional Inputs
Sediment Layer Thickness
Depth of WMU Base Below Ground Surface
Operational Life
Distance to Nearest Surface Water Body
Distance to Ground Water Well
SI
LF, SI, WP
LAU c>d
Sld
WPd
SI
All
m
m
yr
yr
yr
m
m
0.2
0
40
50
20
360
150
0.2
-100a
1
1
1
0
0
100b
100a
200
200
200
5,000
1,609
NA = Not Applicable
a Negative value indicates base is above ground surface; depth value cannot be larger than depth to water table.
b Value cannot be larger than impoundment ponding depth
c For LAUs, operational life should be set to a large enough value to ensure complete leaching from the unit unless the waste
amendment soils are to be physically removed from the unit at the end of the operational life; see discussion below.
d For any WMU, an operation life less than about 5-10 years is too short to ensure that EPACMTP correctly identifies the peak
ground water concentration. Thus, very short operational lives should be used with caution and an awareness that the results are
more uncertain. See Section 2.3 for more details.
WMU Area (m2). This parameter represents the footprint area of the WMU (area = length x
width). This is a required user-input. The area must be entered in square meters.
• WMU Depth (m). If you select Landfill as the WMU type, you must also enter the depth
of the landfill. This parameter represents the average waste thickness in the landfill at
closure. For landfills, this is a required user input value. It does not apply to waste piles or
land application units. For surface impoundments, you must enter an equivalent
parameter, the ponding depth (see below). The landfill depth must be entered in meters.
Ponding Depth (m). This is a required user input parameter for surface impoundments only.
This parameter represents the average depth of free liquid in the impoundment. Surface
impoundments tend to build up a layer of consolidated sludge at their bottom; the thickness of
that layer, if present, should not be counted as part of the ponding depth. The ponding depth must
be entered in meters.
Sediment Layer Thickness (m). This is an optional user input value. It is applicable to surface
impoundments only. This parameter represents the average thickness of accumulated sediment
(sludge) deposited on the bottom of the impoundment. The sediment layer thickness must be
entered in meters. The default value is 0.2 m.
Depth of the WMU Base Below Ground Surface (m). This is an optional user input value It
represents the depth of the base of the unit below the ground surface, as schematically depicted in
Figure 4-2. The depth of the unit below the ground surface reduces the distance in the
unsaturated zone through which leachate constituents have to travel before they reach ground
water. This depth must be entered in meters. The default value is 0 m, i.e., the base of the unit is
level with the ground surface. There may be circumstances in which the base of the WMU is
elevated above the ground surface. IWEM can handle this situation in two ways:
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IWEM User's Guide Understanding Your IWEM Input Values
* If you know the depth to ground water of your site, you can enter the total vertical
distance between the base of the WMU and the water table as the Depth of the Water
Table in the Subsurface Parameters (8) screen. In this case, set the Depth of the WMU
Base Below Ground Surface to zero (0).
• If you do not know the depth to the water table, then you can enter the elevation of the
WMU base as a negative value for the Depth of the WMU Base Below Ground Surface.
For instance, if the unit is 1 meter above ground surface, enter a value of-1 as the depth.
WASTE MANAGEMENT UNIT
GROUND SURFACE
DEPTH OF THE WMU BASE
BELOW GROUND SURFACE
WATER TABLE y
DEPTH TO WATER TABLE
NER
SATURATED ZONE
THICKNESS
//&/&/&/&/&//^
Figure 4-2. WMU with base below ground surface.
Operational Life (yr). For waste piles, surface impoundments, or land application units, the
operational life is an optional user input parameter. The operational life represents the number of
years the WMU is in operation, or, more precisely for the purpose of IWEM, the number of years
the unit releases leachate. This parameter does not apply to landfills, because each landfill is
assumed closed with waste in place and the time required to deplete the contaminants in a landfill
waste is calculated for the user by IWEM. Default values for this parameter are as follows:
• Surface Impoundment = 50 years
• Waste Pile = 20 years
• Land Application Unit = 40 years
Unless waste-amended soils are to be removed from the unit at the end of the operational life,
operational life for land application units should be set at a long enough time to allow complete
leaching of all contaminants from the unit. The length of time required to deplete the mass of
each constituent from the land application unit can be calculated using Equation 3-1 from Section
3.2.1 of the Technical Background Document, assuming that the concentration of the leachate
remains constant through time. Inputs to this equation include the constituent-specific total
concentration; the leachate concentration; the infiltration rate (leachate flux rate); the depth of the
soil amendment; the fractional volume; and the bulk density, which is not a sensitive parameter
(a reasonable estimate for this purpose is 1.8 g/cm3). The longest time to deplete across all
constituents to be modeled is a reasonable, conservative estimate of operational life of the land
application unit.
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IWEM User's Guide Understanding Your IWEM Input Values
Distance to Nearest Surface Water Body (m). For surface impoundments, IWEM needs to
know whether or not there is a permanent surface water body within 2,000 m of the WMU, (i.e.,
a river, pond, or lake). This parameter is used in the calculation of ground water mounding to cap
the infiltration rate from surface impoundments. The surface water body does not have to be
located in the direction of ground water flow and can be in any direction from the WMU unit. If
you know the distance to the nearest surface water body, IWEM will use that value. If the
distance is unknown or known with some uncertainty, IWEM provides the following options:
• Distance to surface water body is unknown (IWEM uses 360 m)
• Exact distance is unknown but it is less than 2,000 m (IWEM uses 360 m)
• Exact distance is unknown but it is greater than 2,000 m (IWEM uses 5,000 m).
Distance to Nearest Well (m)._This parameter represents the distance, in the direction of
downgradient ground water flow, to an actual or potential ground water exposure location. This
exposure location can be represented as a ground water well. Figure 4-3 depicts how the well
distance is measured. This figure shows a plan view (upper graph) and a cross-sectional view
(lower graph) of a ground water constituent plume emanating from a WMU. The WMU is
represented as the dark rectangular area in the figure. The constituent plume is represented by the
lighter shaded area. In this figure, the direction of ground water flow underneath the WMU is
from left to right. The constituent plume follows the direction of ground water flow, but as it
moves, the plume also spreads laterally (upper graph) as well as vertically (lower graph). In
IWEM, these processes are modeled by EPACMTP. Figure 4-3 also shows the location of the
well.
For WMUs, IWEM always assumes that the well is located along the centerline of the plume.
The distance between WMU and the location of the well is an optional user input parameter. This
parameter must be entered in meters, and has a default value of 150 m (492 ft). To enter a site-
specific value, determine the direction of ground water flow, and then the horizontal distance to
the nearest well (or location at which you want to ensure that constituent concentrations in
ground water do not exceed protective levels) along the direction of ground water flow. If you are
unsure of the ground water flow direction, it will be conservative to enter the shortest distance
between the edge of the WMU and the nearest location of concern.
For compatibility with the EPACMTP ground water model and consistency with related EPA
programs, IWEM assumes the well is located within 1,609 m (1 mile) of the WMU, and will not
accept larger values.
IWEM may not be an appropriate model for a well that is very close to the
source (i.e., less than about 5 m). The maximum ground water exposure
concentration will likely be found at a distance of 5 m or greater due to the Sec 6 1 3
combination of a random well intake depth and the penetration depth of the leachate plume. See
Section 6.1.3 of the Technical Background Document for additional discussion.
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PLAN VIEW
CONTAMINANT
PLUME
CENTERLINE
WMU
SECTIONAL VIEW
DOWNGRADIENT DISTANCE (X)
WELL
LOCAT1ON
LAND SURFACE
Figure 4-3. Position of the modeled well relative to the WMU.
While IWEM allows you to enter a site-specific value for the distance between the well and the
WMU, the model does not allow you to modify the depth of the well intake point below the
water table (see Sectional View in Figure 4.3). In IWEM evaluations, the depth of the well intake
point is always treated as a Monte Carlo parameter. In other words, the tool will vary the well
depth during the model simulations, from zero (right at the water table) to a maximum depth of
10 m (30 ft) below the water table. If the value for the saturated thickness of your aquifer is less
than 10m, IWEM will use that actual depth as the maximum value for the well depth. Also,
IWEM does not allow you to vary the distance from the center line of the plume.
If the objective is to determine the maximum possible ground water impact, a recommended
approach would be to experiment with the distance from the WMU, gradually increasing the
distance from 1 meter until the 90th percentile concentration reaches a definitive maximum
value. The distance that generates the maximum value will be sensitive to the initial penetration
depth of the leachate plume at the down-gradient edge of the WMU. Higher values of infiltration
and source area will result in deeper penetration depths.
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4.2.2 Structural Fill Source Parameters
Structural fills are modeled in IWEM as unlined landfills, with a few additional
parameters (bulk density, hydraulic conductivity, and volume fraction occupied by
teachable materials). Table 4-2 provides a list of the IWEM structural fills input
parameters. The following sections discuss the input parameters in more detail.
Table 4-2. IWEM Input Parameters: Structural Fills
TBD
Sec. 3.2
Sec. 6.2
Parameter
Units
Default Value
If No User
Input
Allowable Range
Minimum
Maximum
Required Inputs
Area of the structural fill
Depth of the structural fill
Effective bulk density
Effective hydraulic conductivity
Volume fraction occupied by leachable
material
m2
m
g/cm3
m/yr
-
NA
NA
NA
NA
NA
1
>0
>0
>0
>0
1.0E+8
10
2.1
1x1Q8
1
Optional Inputs
Depth of fill base below ground surface
Distance to Ground water Well
m
m
0
150
-100a
0
100a
1,609
NA = Not Applicable
a Negative value indicates base is above ground surface; depth value cannot be larger than depth to water
table.
Area of Structural Fill (m2). This parameter represents the footprint area of the structural fill
(area = length x width). This is a required user-input. The area must be entered in square meters.
Depth of the structural fill (m). This parameter represents the average thickness of the fill
material. This is a required user input value. The fill depth must be entered in meters.
Depth of the Fill Base Below Ground Surface (m). This is an optional user input value. It
represents the depth of the base of the fill below the ground surface, as schematically depicted in
Figure 4-2. The depth of the fill below the ground surface reduces the distance in the unsaturated
zone through which leachate constituents have to travel before they reach ground water. This
depth must be entered in meters. The default value is 0 m, i.e., the base of the unit is level with
the ground surface. There may be circumstances in which the base of the WMU is elevated above
the ground surface. IWEM can handle this situation in two ways:
• If you know the depth to ground water of your site, you can enter the total vertical
distance between the base of the fill and the water table as the Depth of the Water Table
in the Subsurface Parameters (8) screen. In this case, set the Depth of the Fill Base Below
Ground Surface to zero (0).
• If you do not know the depth to the water table, then you can enter the elevation of the fill
base as a negative value for the Depth of the Fill Base below Ground Surface. For
instance, if the unit is 1 m above ground surface, enter a value of-1 as the depth.
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Distance to Nearest Well (m)._This parameter represents the distance, in the direction of
downgradient ground water flow, to an actual or potential ground water exposure location. This
exposure location can be represented as a ground water well. Figure 4-3 depicts how the well
distance is measured. For structural fills, IWEM always assumes that the well is located along the
centerline of the plume. The distance between fill and the location of the well is an optional user
input parameter. This parameter must be entered in meters, and has a default value of 150 m (492
ft). To enter a site-specific value, determine the direction of ground water flow, and then the
horizontal distance to the nearest well (or location at which you want to ensure that constituent
concentrations in ground water do not exceed protective levels) along the direction of ground
water flow. If you are unsure of the ground water flow direction, it will be conservative to enter
the shortest distance between the edge of the fill and the nearest location of concern.
IWEM may generate unreliable results for a well that is very close to the
roadway (i.e., less than about 5 m). The maximum ground water exposure
concentration will likely be found at a distance of 5 m or greater due to the Sec 6 1 3
combination of a random well intake depth and the penetration depth of the leachate plume. See
Section 6.1.3 of the Technical Background Document for additional discussion.
For compatibility with the EPACMTP ground water model and consistency with related EPA
programs, IWEM assumes the well is located within 1,609 m (1 mile) of the fill, and will not
accept larger values.
While IWEM allows you to enter a site-specific value for the distance between the well and the
fill, the model does not allow you to modify the depth of the well intake point below the water
table (see Sectional View in Figure 4.3). In IWEM evaluations, the depth of the well intake point
is always treated as a Monte Carlo parameter. In other words, the tool will vary the well depth
during the model simulations, from zero (right at the water table) to a maximum depth of 10 m
(30 ft) below the water table. If the value for the saturated thickness of your aquifer is less than
10m, IWEM will use that actual depth as the maximum value for the well depth. Also, IWEM
does not allow you to vary the distance from the center line of the plume.
Effective Hydraulic Conductivity of Fill Material (m/yr). The effective hydraulic
conductivity of the fill material in meters per year. This parameter is required for
determining the limiting value of infiltration through the fill. The best source for this
parameter would be engineering design reports or material properties sheets. Values
for representative materials are provided in Table 6-17 of Section 6.4.3.2 of the Technical
Background Document in units of cm/sec. IWEM requires units of m/yr for hydraulic
conductivity.
Effective Bulk Density of Fill Material (g/cm3). The dry bulk density of the layer material in
grams per cubic centimeters. This parameter is required for calculating how long a contaminant
leaches from fill containing industrial materials. The best source for this parameter would be
engineering design reports or material properties sheets.
Volume Fraction Occupied by Leachable Material (Unitless). This parameter represents the
portion of the fill containing teachable industrial materials. It must be greater than 0 and less than
or equal to 1.
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4.2.3 Roadway Source Parameters
To understand the roadway source parameters, it is helpful to understand the general
conceptualization of the roadway source and the terminology used to define a
roadway design. These are summarized briefly here, but please refer to Section 3.2
of the Technical Background Document for a more detailed discussion.
TBD
Sec. 3.3
Sec. 6.3
Figure 4-4 depicts a typical roadway with
a segment constructed with byproduct
materials. For the purposes of model
simplicity, that segment is assumed to be
nearly linear and thus can be
approximated by the straight line segment
AB. If the segment to be modeled is long
and meandering, it must be subdivided
into several nearly linear segments that
can each be represented by a straight line.
In this figure, the arrow showing
"regional flow direction" is the direction
of ground water flow, and the red circle
labeled "receptor location" is the well.
Figure 4-5 shows a sample cross-section
of a possible roadway. This is not the
only possible configuration, but includes
most of the possible components.
Highway
Regional Flow Direction
Linear Approximation of the
Highway Segment of Interest
Receptor
Location
Figure 4-4. A typical roadway with a recycled-
material segment.
Runoff ]
L
Runoff
Traveled Lanes
Traveled Lanes
Col ected
leachate Subgrade
Drain
Collected
leachate
Figure 4-5. Sample road design cross-section.
The roadway includes not just the paved road surface, but other structures such as a median,
road shoulders, embankments, and ditches. The roadway shown in Figure 4-5 is largely
symmetrical, other than the presences of three travel lanes on one side and only two on the other,
but your roadway design is not required to be symmetrical.
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The width of the roadway is divided into strips. In the figure, 10 strips are shown. Starting from
the left, they are a ditch, an embankment, two travel lanes, the median, three more travel lanes,
another embankment, and another ditch.
The strips are further divided vertically into layers, although not all strips have more than one
layer. In the figure, the ditches, embankments, and median are a single layer, but the travel lanes
have three layers: starting at the top, those are pavement, drain, and subgrade.
A drain is a special layer that moves water from underneath the roadway to a ditch. It may
traverse and drain several strips, and the layers below it must be homogeneous across all strips
from which the drain collects percolating water.
A ditch is a special strip that receives drainage and runoff. You do not have to have a drain to
have a ditch, but you must have a ditch to have a drain. A ditch must be a single layer.
It will probably be helpful to sketch your roadway design before you try to enter the data
describing it to IWEM. It may also be helpful to identify materials for each strip and layer, and
look up properties of those materials (e.g., hydraulic conductivity, dry bulk density, Manning's
coefficient) in advance.
Table 4-3 lists all the roadway parameters. The parameters are discusses following the table.
Table 4-3. IWEM Input Parameters: Roadway Source Geometry
Parameter
Units
Required?
Allowable Range
Minimum
Maximum
Well Location Parameters
Angle between roadway and ground water flow
Location of receptor well relative to 90° line from
roadway edge
Shortest distance between roadway edge and
monitoring well (Distance D)
Distance along roadway from point at which
distance measurement was made to midpoint of
roadway segment (Distance L)
The angle between roadway and ground water flow:
- if Region 1 selected above
- if Region II selected above
degrees
"
m
m
degrees
Yes
Yes
Yes
Yes
Yes
>0-90°
Region 1
(above 90°
line)
>0
0
>o°
>90°
>90°
Region II
(below 90°
line)
1,609
1,609
<90°
<180°
Roadway Geometry Parameters
General Geometry Parameters
Number of roadway strips
Number of drains
Roadway segment length
-
-
m
Yes
No
Yes
1
0
>0
15
2
none
(continued)
Roadway Geometry Parameters (continued)
Roadway Geometry Parameters
Strip type
Yes
paved, median, shoulder,
embankment, ditch
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Table 4-3. IWEM Input Parameters: Roadway Source Geometry
Parameter
Width
Number of layers
Units
m
-
Required?
Yes
Yes
Allowable Range
Minimum
>0
1
Maximum
none
1 for drains
5 for all others
Drain Geometry - Configuration
Drained strips (can specify more than one)
Ditch strip that the drain discharges into
Layer that the drain lies over
-
-
-
Yes if Drain
is defined
Yes if Drain
is defined
Yes if Drain
is defined
Must be a non-ditch strip
Must be a strip defined as a
ditch
Must be a non-drain layer
Roadway Material Properties
Layer Properties
Layer type
Thickness
Hydraulic conductivity of layer material
Dry bulk density of layer material
-
m
m/yr
g/cm3
Yes
Yes
Yes
Yes
subbase, base, fill, pavement,
subgrade, grade
>0
>0
>0
none
1x-|08
3.0
Ditch Properties
Manning's n coefficient
Slope of the ditch
Maximum water depth in the ditch
Is there a gutter?
Location of gutter(s) (between what strips)
unitless
m/m
m
-
-
Yes if Ditch
is defined
Yes if Ditch
is defined
Yes if Ditch
is defined
No
Yes if Gutter
is defined
0.01
0
>0
0.1
0.15
none
yes or no (default is no)
must be two contiguous strips
Drain Properties
Thickness
Hydraulic conductivity
Bulk density of layer material
m
m/yr
g/cm3
Yes if Drain
is defined
Yes if Drain
is defined
Yes if Drain
is defined
>0
>0
>0
none
1x1Q8
3.0
(continued)
Drain and Ditch Flow Characteristics
Percent of Runoff or Flow That Reaches Ditch Strips (for relevant strips and drains)
Percent of roadway runoff that reaches ditch
Percent of flow in drain that reaches ditch
%
%
Yes if Ditch
is defined
Yes if Drain
is defined
0
0
100
100
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Table 4-3. IWEM Input Parameters: Roadway Source Geometry
Parameter
Units
Required?
Allowable Range
Minimum
Flow Paths to Ditch Strips
Ditch strip(s) receiving overland flows
-
Yes if Ditch
is defined
Maximum
Must be a strip defined as a
ditch
TBD
4.2.3.1 Well Location Parameters
IWEM uses the angle between the roadway edge, the ground water flow direction
away from the roadway, and the general location of the well to help determine the
exact location of the well. When you first specify a roadway source, IWEM will first Sec- 6-3-1
ask you to identify the well location and ground water flow direction in general terms in the
popup Location of Well with Respect to Roadway (7a) screen, as shown in Figure 4-6A.
Following this, on the main Source Parameters (7) screen, you will refine these parameters, using
the diagram in Figure 4-6B.
GW flow
Well
A B
Figure 4-6. Diagrams used by IWEM to specify roadway geometry.
It will be helpful to make a diagram of your source before you begin. First, obtain a map,
drawing, or aerial photo depicting the roadway of interest and the receptor well location(s) (or a
surrogate) most vulnerable to potential ground water contamination leaching from the roadway
(if the source document has a scale, this will come in handy later).
Using the diagram in Figure 4-4 as an example, Figure 4-7 identifies the elements you will add.
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Receptor
Re9'on" Location
Figure 4-7. Example roadway source diagram.
1. Draw a rectangle (shown in red) over the stretch of roadway to represent the conceptual,
straight roadway segment (include shoulders or embankments containing any industrial
materials)
2. Draw an arrow (shown in blue) that represents the direction of regional ground water
flow; it is best if this arrow passes through the section of conceptual roadway to be
modeled
3. Draw another line, perpendicular to the roadway that also passes through the roadway's
midpoint (shown in green).
Now, rotate the map until the arrow drawn in Step 3 is pointing to the right or due east. You have
created a representation that will allow you to specify the angle range and the general location of
the well on this dialog. You can also measure (with a protractor) the angle between the ground
water flow direction and the roadway edge. If the map, drawing, or aerial photo is to scale, then
this document can also be used to determine the required length measurements described below.
General Layout (Screen 7a)
Angle between roadway and ground water flow (degrees). This input can be >0° and < 90° or
>90° and <180°, and determines the direction of the GW flow relative to the roadway. In the
example in Figure 4-7, this angle is between 0 and 90°.
Location of receptor well relative to 90° line from roadway edge. The well can be in either
Region I (above the 90° line from the center point of the roadway segment length) or Region II
(below the 90° line). In the example in Figure 4-7, the well is in Region II.
Detailed Layout (Screen 7)
Shortest distance between roadway edge and monitoring well (m). This is the distance from
the well to the roadway along a line perpendicular to the roadway length. This parameter labeled
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TBD
as D in Figure 4-7. To convert other units to meters, use the conversion factors above. IWEM
may generate unreliable results for a well that is very close to the source (i.e.,
less than about 5 m). The maximum ground water exposure concentration will
likely be found at a distance of 5 m or greater due to the combination of a random Sec 6.1.3
well intake depth and the penetration depth of the leachate plume. See Section 6.1.3
of the Technical Background Document for additional discussion.
Distance along roadway from point at which distance measurement was made to midpoint
of roadway segment (m). This is the distance from the midpoint of the roadway segment length
to the location where the distance between the roadway edge and well was measured. This
parameter labeled as L in Figure 4-7.
The angle between roadway and ground water flow (degrees). This is the actual angle
between the ground water flow and roadway; earlier, you specified whether this was less than or
greater than 90°; now you will specify the actual angle. It must be consistent with the range you
selected earlier, and it must be less than 180°. In Figure 4-7, the angle is 45°.
It is possible that your combination of receptor location parameters defines a scenario that cannot
be simulated by IWEM. EPACMTP can only simulate a receptor well that is down-gradient of
the leachate source where ground water flow is perpendicular to the source of leachate. In order
to accommodate non-perpendicular ground water flow directions, IWEM applies a
geometric transformation to your conceptual model that allows IWEM and
EPACMTP to represent non-perpendicular flow as perpendicular. The details of the
transformation are presented in Appendix F of the Technical Background Document.
TBD
App. F
Before Transformation
After Transformation
Reg io n a IF low Direction
Figure 4-8 provides an example of how the transformation process can result in a receptor
location behind the down-gradient edge of the transformed roadway. The transformation process
rotates the roadway such that it
becomes perpendicular to the ground
water flow direction. The length and
width of the transformed roadway are
determined so as to maintain the mass
balance of the teachable constituents
contained in the materials and to create
an identical dissolved plume shape and
extent. In general, a receptor well that
is placed near or beyond the end of the
roadway away from the direction of
ground water flow will increase the
likelihood that the transformed
geometry will be invalid.
If IWEM determines that your
Receptor
Location
Receptor
Location
Figure 4-8. Example of invalid receptor location after
geometric transformation.
combination of ground water flow direction and receptor well location are not valid, you will not
be able to proceed. Your options are to modify either the ground water flow direction, receptor
location, or both, and continue.
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IWEM User's Guide Understanding Your IWEM Input Values
4.2.3.2 General Geometry Parameters
Number of roadway strips. As described above, a roadway strip is a portion of the PfBD
width of the roadway you are modeling. Together, the strips make up the overall L=*=
width of the roadway. Strips include both the actual road and strips along the side or Sec 6 3 2
down the middle that are not actual driving surface (such as shoulder or median). The number of
strips is a required input.
Number of drains. A drain moves water from underneath the roadway to a ditch. Thus, you
must define at least one strip as a ditch before you can add the number of drains. IWEM allows a
maximum of two drains.
Roadway segment length (m). This is the length of the road segment you want to model.
4.2.3.3 Roadway Geometry Parameters Tab
In this tab, IWEM displays a table with a row for each strip, up to the number of flBD
strips you specified above. The strips are automatically numbered from 1 to the
number you specified. Strip 1 is the strip closest to the well, and the strip numbers Sec 6 3 3
increase with distance from the well. The following inputs must be specified for each strip:
Strip type. Choose a strip type from the dropdown box. Options are paved area, median,
shoulder, embankment, and ditch.
Width (m). Enter the width of the strip in meters.
Number of layers. The number of vertical layers in each strip other
than drains. You will specify the properties of these layers later.
Do not count drains
in the number of
layers!
If you defined any of the strips as a ditch, you will have the option to
enter the number of drains above the table (see Section 4.2.2.2,
General Parameters). IWEM allows a maximum of two drains.
If you specify a non-zero number of drains, IWEM will display two Drain Geometry
tables.
Sec. 6.3.4
• Drain Geometry-Strips Table
- Drained Strip(s). For each drain (drain 1 is the one nearest to the well), specify the
strip (or strips) that are drained by the drain. The strips drained by a drain must be
located above the drain.
• Drain Geometry-Configuration Table
- Ditch strip that the drain discharges into. This is the strip number of the ditch that
the drain discharge into. It does not have to be on the same side of the roadway as the
drain; you can specify two drains and one ditch and have both drains drain to the one
ditch.
- Layer that the drain lies over. This is the layer number for the layer below the drain.
Layers are numbered from 1 to the number of layers from the bottom up.
Note the following about drain layout:
• Two drains can be connected to a single ditch
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IWEM User's Guide Understanding Your IWEM Input Values
* A drain can traverse one or more contiguous roadway strips, however, drains cannot
overlap each other.
• If a drain traverses multiple, contiguous strips:
- The number of layers in each strip beneath the drain must be the same, and
- The thickness and material properties of each like numbered layer beneath the drain
must also be same.
• Each drain requires values for the material hydraulic conductivity and dry bulk density.
4.2.3.4 Layer Properties Tab
On this tab, IWEM displays a table containing a row for each strip-layer combination
based on your inputs on the geometry tab. The strip number, strip type, and layer
number columns are prepopulated. The Is Below Drain column is also prepopulated Sec. 6.3.5
based on your entries in the Drain Geometry Configuration table on the Geometry
tab. Remember that drains are not included in the layers; drain properties are specified on the
Drain Properties tab. You must then provide the following inputs for each strip-layer:
Layer type. Choose a layer type from the dropdown box. Options are
subbase, base, fill, pavement, subgrade, and grade.
Note that all layers below a
particular drain must be
homogeneous with respect
to these properties - you
must specify the same
type, same thickness,
same hydraulic
conductivity, and same dry
bulk density. If two layers
that underlie the same
drain are not the same,
you will get an error
Thickness (m). The thickness of the layer in meters. This parameter is
required for calculating how long a contaminant leaches from the
layer. To convert other units to meters, use the conversion factors
above. The best source for this parameter would be engineering
design reports.
Hydraulic conductivity of layer material (m/yr). The hydraulic
conductivity of the layer material in meters per year. This parameter is
required for determining the limiting value of infiltration through the
layers of a strip. The best source for this parameter would be engineering design report or
material properties sheets. Values for representative materials are provided in Table
6-17 of Section 6.4.3.2 of the Technical Background Document in units of cm/sec.
IWEM requires units of m/yr for hydraulic conductivity. Sec-
Dry bulk density of layer material (g/cm3). The dry bulk density of the layer
material in grams per cubic centimeters. This parameter is required for calculating how long a
contaminant leaches from a layer containing industrial material. The best source for this
parameter would be engineering design reports or material properties sheets.
4.2.3.5 Ditch Properties Tab
In this tab, IWEM displays rows for each strip that you specified was a ditch. flBD
Manning's n coefficient (unitless). Manning's n coefficient is a non-dimensional Sec 6 3 6
coefficient that reflects the hydraulic resistance induced from the roughness of the
channel surface for open channel flow. A smooth channel generally has less hydraulic resistance
and is represented by a lower coefficient value, resulting in higher velocity estimates. A rough
channel is generally more hydraulically resistant and has correspondingly higher coefficient
values. Chow (1959) compiled many values for Manning's n for a wide range of channel
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IWEMUser's Guide
Understanding Your IWEM Input Values
conditions. Table 4-4 presents values for n corresponding to typical roadside drainage
conditions.
Table 4-4. Manning's n for Typical Roadside Channels (Chow, 1959)
Type of Channel and Description
Minimum
Normal
Maximum
Excavated or Dredged Channels
Earth, Straight and Uniform
Clean, recently completed
Clean, after weathering
Gravel, uniform section, clean
With short grass, few weeds
0.016
0.018
0.022
0.022
0.018
0.022
0.025
0.027
0.02
0.025
0.03
0.033
Earth Winding and Sluggish
No vegetation
Grass, some weeds
Dense weeds or aquatic plants in deep channels
Earth bottom and rubble sides
Stony bottom and weedy banks
Cobble bottom and clean sides
0.023
0.025
0.03
0.028
0.025
0.03
0.025
0.03
0.035
0.03
0.035
0.04
0.03
0.033
0.04
0.035
0.04
0.05
Dragline-Excavated or Dredged
No vegetation
Light brush on banks
0.025
0.035
0.028
0.05
0.033
0.06
(continued)
Rock Cuts
Smooth and uniform
Jagged and irregular
0.025
0.035
0.035
0.04
0.04
0.05
Channels Not Maintained, Weeds and Brush Uncut
Dense weeds, high as flow depth
Clean bottom, brush on sides
Same as above, highest stage of flow
Dense brush, high stage
0.05
0.04
0.045
0.08
0.08
0.05
0.07
0.1
0.12
0.08
0.11
0.14
Constructed Channel with Vegetal Lining
Constructed channel with vegetal lining
0.03
0.5
Slope of the ditch (m/m). This is the slope of the ditch along the length of the roadway. The
slope can be calculated as the change in elevation of the ditch bed over its length divided by the
length of the ditch. The slope should be set to zero if there is stagnant water in the ditch (no
flow).
Maximum water depth in the ditch (m). Maximum water depth is typically the depth of the
ditch.
Is there a gutter? A gutter is a channel that captures runoff (overland flow) from the roadway,
preventing some or all of it from reaching the ditch. This is a checkbox; leave it blank if there is
no gutter (which is the default).
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IWEM User's Guide Understanding Your IWEM Input Values
Location of gutter(s) (between what strips). If you specified that the ditch does have a gutter,
fill in here between what strips the gutter lies in. The specified strips must be contiguous, and
they must both be strips for which runoff flows to that ditch, as specified in the Flow Paths to
Ditch Strips table on the Flow Characteristics tab.
4.2.3.6 Drain Properties Tab
IWEM displays rows for each drain you specified. Note that width of the drain is FrBD
predetermined by the widths of the strips that it drains.
Sec. 6.3.7
Thickness (m). The thickness in meters of the drain. This parameter is required for
calculating how long a contaminant leaches through the drainage layer. Note that the drainage
layer cannot be a source of leachate (so no leachate concentration may be assigned to it), but
leachate from layers above the drain can leach through the drain material.
Hydraulic conductivity (m/yr). The hydraulic conductivity of the drain material in FfBD
meters per year. This parameter is required for determining the limiting infiltration
rate across layers in a strip. The best source for this parameter would be engineering
Sec.
' i
design reports or material properties sheets. Values for representative materials are
provided in Table 6-17 of Section 6.4.3.2 of the Technical Background Document in units of
cm/sec. IWEM requires units of m/yr for hydraulic conductivity.
Bulk density of layer material (g/cm3). The dry bulk density of the drain material in grams per
cubic centimeters. This parameter is required for calculating how long a contaminant leaches
through the drainage layer. Note that the drainage layer cannot be a source of leachate (so no
leachate concentration may be assigned to it), but leachate from layers above the drain can leach
through the drain material. The best source for this parameter would be engineering design
reports or material properties.
Each drain requires values for the material hydraulic conductivity and dry bulk density. Bear in
mind that a drain is designed to be a permeable, transmissive layer; thus, it should have a
relatively high hydraulic conductivity.
4.2.3.7 Flow Characteristics Tab [TBD
Flow Percentages to Ditch Strips Table Sec 6 3 8
IWEM displays rows for each drain and each ditch. Each will have one of the following two
inputs that you must enter:
Percent of roadway runoff that reaches ditch beyond gutter (%).This parameter must be
provided when a gutter defined for a ditch. A gutter is used to divert some or all of the runoff
water from strips "above" the gutter, away from the associated ditch and out of the modeled
system. The value you supply here, a percentage ranging from 0 to 100%, specifies how much of
the runoff is not diverted by the gutter. A value of 0% indicates that no runoff water from strips
above the gutter will reach the ditch. A value of 100% indicates that all runoff water from strips
above the gutter will reach the ditch. If a gutter is not present, then 100% of the runoff should
reach the ditch. If a gutter is present, the percentage should be equal to the ratio of the width of
all strips between the gutter and the ditch to the width of all strips that are associated with the
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IWEM User's Guide Understanding Your IWEM Input Values
ditch (See Section 3.4.2.3 under Ditch Properties and Flow Characteristics and the section
below, Ditch strip(s) receiving overland flows).
Percent of flow in drain that reaches ditch (%).This parameter accounts for the possibility that
not all infiltrating water, and the constituents dissolved in that water, is diverted by the permeable
layer or drain to its associated ditch. A value must be provided for each defined drain, a
percentage ranging from 0 to 100%, to indicate how much of the infiltrate entering the drain is
diverted to the ditch. A value of 0% indicates that no drainage flow will reach the ditch. A value
of 100% indicates that all infiltrate entering the drain will be diverted to the ditch. Selecting a
value for a drain will depend on the continuity of the drain in the direction of travel. If the drain
is represented as a continuous layer of highly permeable material, then the value would tend to be
low. If, however, drainage pipe is used at intervals, then the value could be estimated as a ratio of
the area drained by the drainage pipe to the entire area of the roadway underlain by the drain.
Flow Paths to Ditch Strips Table
IWEM displays a row for each non-ditch strip specified.
Ditch strip(s) receiving overland flows. Specify which ditch strip receives runoff from each
strip. You must specify a strip defined as a ditch. Note that if you placed a gutter between two
strips on the Ditch Properties tab, runoff from both those strips must flow to the ditch associated
with the gutter.
4.3 Fate and Transport Parameters
Fate and transport parameters are divided into two tabs: subsurface parameters and hydrologic
(infiltration and recharge) parameters.
4.3.1 Subsurface Parameters
The subsurface parameters in IWEM comprise a group of the most important ground PrBD
water modeling parameters. Unfortunately, these parameters are not easily measured.
Obtaining site-specific values for these parameters requires a hydrogeological site
characterization. Such information may be available from WMU planning and siting
studies, environmental impact assessments, and RCRA permit applications. The United States
Geological Survey (www.usgs.gov) and your local state geological survey may also be good
sources of site-specific information.
To assist you in performing an IWEM evaluation, IWEM provides three options for entering
subsurface parameters to assist you in making the best possible use of information you have. The
more site specific parameters you can specify, the less uncertain the results. In order from most
preferred (least uncertainty) to least preferred (most uncertainty), those options are as follows:
• Use accurate site-specific values for all of the parameters, entering them directly in the
appropriate data input screens.
• If you have values for some, but not all, of the parameters , enter the parameter values
that you know, and IWEM will make a best estimate of the missing values, utilizing
information from IWEM's national ground water modeling database about how the
various parameters tend to be correlated.
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* If you have no site-specific subsurface data whatsoever, IWEM can simply assigns
average parameter values from its database.
Table 4-5 summarizes the subsurface input parameters. The individual IWEM parameters in this
group are discussed below.
Table 4-5. IWEM Input Parameters: Subsurface Parameters
Parameter
Units
Default
Value if No
User Input
Allowable Range
Minimum
Maximum
Optional Inputs
Subsurface Environment
Subsurface pH
- Solution limestone environment
- All other environments
Depth to Water Table
Aquifer Hydraulic Conductivity
Regional Hydraulic Gradient
Aquifer Thickness
-
-
m
m/yr
m/m
m
Unknown
7.5
6.2
5.2a
1,890a
0.00573
10.1a
NA
7
1
0.1
3.15
>0
0.3
NA
14
14
1,000
1x108
1
1,000
NA = Not Applicable
a If you specify a subsurface environment, IWEM will treat as a Monte-Carlo variable and use a
distribution of values that is appropriate for the selected subsurface environment. Otherwise, if you
select "unknown" subsurface environment, IWEM will use the value shown.
Subsurface Environments. IWEM includes a built-in database of hydrogeological parameters,
organized by 12 different subsurface environments, plus one 'unknown' category.
A summary of the geologic and hydrogeologic characteristic of each environment follows;
however, the Agency cautions that the assignment of a subsurface environment is best done by a
professional trained in hydrogeology and familiar with local site conditions:
• Igneous and Metamorphic Rocks: This hydrogeologic environment is underlain by
consolidated bedrock of volcanic origin. This hydrogeologic environment setting is
typically associated with steep slopes on the sides of mountains, and a thin soil cover.
Igneous and metamorphic rocks generally have very low porosities and permeabilities.
This hydrogeologic environment can occur throughout the United States, but is most
prevalent in the western United States.
• Bedded Sedimentary Rock: Sedimentary rock is formed through erosion of bedrock.
Deposited layers of eroded material may later be buried and compacted to form
sedimentary rock. Generally, the deposition is not continuous but recurrent, and sheets of
sediment representing separate events come to form distinct layers of sedimentary rock.
Typically, these deposits are very permeable and yield large quantities of ground water.
Examples of this hydrogeologic environment setting are found throughout the United
States.
• Till Over Sedimentary Rock: This hydrogeologic environment is found in glaciated
regions in the northern United States, which are frequently underlain by relatively flat-
lying consolidated sedimentary bedrock consisting primarily of sandstone, shale,
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limestone, and dolomite. The bedrock is overlain by glacial deposits which, consists
chiefly of till, a dense unsorted mixture of soil and rock particles deposited directly by ice
sheets. Ground water occurs both in the glacial deposits and in the sedimentary bedrock.
Till deposits often have low permeability.
• Sand and Gravel: Sediments are classified into three categories based upon their relative
sizes; gravel, consisting of particles that individually may be boulders, cobbles or
pebbles; sand, which may be very coarse, coarse, medium, fine or very fine; and mud,
which may consist of clay and various size classes of silt. Sand and gravel hydrogeologic
environments are very common throughout the United States and frequently overlie
consolidated and semi- consolidated sedimentary rocks. Sand and gravel aquifers have
very high permeabilities and yield large quantities of ground water.
• Alluvial Basins, Valleys and Fans: Thick alluvial deposits in basins and valleys
bordered by mountains typify this hydrogeologic environment. Alluvium is a general term
for clay, silt, sand and gravel that was deposited during comparatively recent geologic
time by a stream or other body of running water. The sediments are deposited in the bed
of the stream or on its flood plain or delta, or in fan shaped deposits at the base of a
mountain slope. Alluvial basins, valleys and fans frequently occupy a region extending
from the Puget Sound-Williamette Valley area of Washington and Oregon to west Texas.
This region consists of alternating basins or valleys and mountain ranges. The
surrounding mountains, and the bedrock beneath the basins, consist of granite and
metamorphic rocks. Ground water is obtained mostly from sand and gravel deposits
within the alluvium. These deposits are interbedded with finer grained layers of silt and
clay.
• River Alluvium with Overbank Deposits: This hydrogeologic environment is
characterized by low to moderate topography and thin to moderately thick sediments of
flood-deposited alluvium along portions of a river valley. The alluvium is underlain by
either unconsolidated sediments or fractured bedrock of sedimentary or
igneous/metamorphic origin. Water is obtained from sand and gravel layers that are
interbedded with finer grained alluvial deposits. The alluvium typically serves as a
significant source of water. The flood plain is covered by varying thicknesses of fine-
grained silt and clay, called overbank deposits. The overbank thickness is usually greater
along major streams and thinner along minor streams but typically averages 1.5 to 3 m (5
to 10ft).
• River Alluvium without Overbank Deposits: This hydrogeologic environment is
identical to the River Alluvium with Overbank Deposits environment except that no
significant fine-grained floodplain deposits occupy the stream valley. The lack of fine-
grained deposits may result in significantly higher recharge in areas with ample
precipitation.
• Outwash: Sand and gravel removed or "washed out" from a glacier by streams is termed
outwash. This hydrogeologic environment is characterized by moderate to low
topography and varying thicknesses of outwash that overlie sequences of fractured
bedrock of sedimentary, metamorphic or igneous origin. These sand and gravel outwash
deposits typically serve as the principal aquifers within the area. The outwash also serves
as a source of regional recharge to the underlying bedrock.
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* Till and Till Over Outwash: This hydrogeologic environment is characterized by low
topography and outwash materials that are covered by varying thicknesses of glacial till.
The till is principally unsorted sediment, which may be interbedded with localized
deposits of sand and gravel. Although ground water occurs in both the glacial till and in
the underlying outwash, the outwash typically serves as the principal aquifer because the
fine grained deposits have been removed by streams. The outwash is in direct hydraulic
connection with the glacial till and the glacial till serves as a source of recharge for the
underlying outwash.
• Unconsolidated and Semi-consolidated Shallow Surficial Aquifers: This
hydrogeologic environment is characterized by moderately low topographic relief and
gently dipping, interbedded unconsolidated and semi-consolidated deposits which consist
primarily of sand, silt and clay. Large quantities of water are obtained from the surficial
sand and gravel deposits which may be separated from the underlying regional aquifer by
a low permeability or confining layer. This confining layer typically "leaks", providing
recharge to the deeper zones.
• Coastal Beaches: This hydrogeologic environment is characterized by low topographic
relief, near sea-level elevation and unconsolidated deposits of water-washed sands. The
term beach is appropriately applied only to a body of essentially loose sediment. This
usually means sand-size particles, but could include gravel. Quartz particles usually
predominate. These materials are well sorted, very permeable and have very high
potential infiltration rates. These areas are commonly ground water discharge areas
although they can be very susceptible to the intrusion of saltwater.
• Solution Limestone: Large portions of the central and southeastern United States are
underlain by limestones and dolomites in which the fractures have been enlarged by
solution. Although ground water occurs in both the surficial deposits and in the
underlying bedrock, the limestones and dolomites, which typically contain solution
cavities, generally serve as the principal aquifers. This type of hydrogeologic environment
is often described as "karst."
• Unknown Environment: If the subsurface hydrogeological environment is unknown, or
it is different from any of the twelve main types used in IWEM, select the subsurface
environment as Type 13. In this case, IWEM will assign values of the hydrogeological
parameters (depth to ground water, saturated zone thickness, saturated zone hydraulic
conductivity, and saturated zone hydraulic gradient) that are simply national average
values.
Subsurface pH. This parameter represents the alkalinity or acidity of the soil and aquifer. The
pH is one of the most important subsurface parameters controlling the mobility of metals. Most
metals are more mobile under acidic (low pH) conditions, as compared to neutral or alkaline (pH
of 7 or higher) conditions. The pH of most aquifer systems is slightly acidic, the primary
exception being aquifers in solution limestone settings. These may also be referred to as karst,
carbonate, or dolomite aquifers. The ground water in these systems is usually alkaline.
IWEM assumes the subsurface pH value is the same in the unsaturated zone and saturated zone.
The default pH value depends on the hydrogeologic environment you selected; if you selected
"Solution Limestone" (Subsurface Environment 12), the default pH is 7.5. In all other
hydrogeologic environments, the default pH value is 6.2. These default values represent median
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IWEM User's Guide Understanding Your IWEM Input Values
values from EPA's Data Storage and Retrieval System, National Water Quality Database
(STORET). If you do not know the hydrogeologic environment, IWEM will assume that the
subsurface environment is of a non-solution-limestone type with the default pH of 6.2.
Depth to the Water Table (m). This parameter is the vertical distance from the ground surface
to the water table as depicted in Figure 4-2. The water table in this case is meant to represent the
natural water elevation, as it is or would be without the influence from the source. The presence
of a WMU, particularly a surface impoundment, may cause a local rise in the water table called
mounding. IWEM assumes that the depth to water table value you have entered does not include
mounding. The tool will calculate the predicted impact of each liner, structural fill design, or
roadway design on the ground water as part of the modeling evaluation.
If the water table elevation at your site shows seasonal fluctuation, it is best to enter an average
annual depth to ground water value. Note that entering a smaller depth to ground water value will
mean that constituents have less distance to travel before they reach the ground water, and IWEM
will tend to estimate higher ground water exposure concentrations. It is also important to
remember that in a WMU evaluation, the depth to ground water should be measured from the
ground surface, not from the base of the WMU. If the base of the unit is lower than the ground
surface and, therefore, closer to the water table, you should enter that value as the Depth of the
WMU Base Below the Ground Surface (see Section 4.2.1 above).
The depth to ground water should be entered in meters. The default value for this parameter is a
function of the selected subsurface environment. If you selected the "unknown" subsurface
environment, IWEM will use the national average of 5.2 m. If you selected one of the 12
subsurface environments and do not specify the depth to the water table, IWEM will treat the
depth to the water table as a Monte-Carlo variable: IWEM will use a distribution of values that is
appropriate for the selected subsurface environment.
Hydraulic Conductivity (m/yr). This parameter represents the permeability of the saturated
aquifer in the horizontal direction. The hydraulic conductivity, together with the hydraulic
gradient, controls the ground water flow rate.
The hydraulic conductivity, together with the hydraulic gradient (see below), controls the ground
water flow rate, in accordance with Darcy's Law. The effect of varying ground water flow rate on
contaminant fate and transport is complex. Intuitively, it would seem that factors that increase the
ground water flow rate would cause a higher ground water exposure level at the receptor well,
but this is not always the case. A higher ground water velocity will cause leachate constituents to
arrive at the well location more quickly. For constituents that are subject to degradation in ground
water, the shorter travel time will cause the constituents to arrive at the well at higher
concentrations as compared to a case of low ground water velocity and long travel times. On the
other hand, a high ground water flow rate will tend to increase the degree of dilution of the
leachate plume, due to mixing and dispersion. This will in turn tend to lower the magnitude of
the concentrations reaching the well. IWEM evaluations are based on the maximum constituent
concentrations at the well, rather than how long it might take for exposure to occur, and therefore
a higher ground water flow rate may result in lower estimated exposure levels at the well.
Siting a source in a low permeability aquifer setting is not always more protective than a high
permeability setting. Low ground water velocity means that it will take longer for the exposure to
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IWEM User's Guide Understanding Your IWEM Input Values
occur, and as a result, there is more opportunity for natural attenuation to degrade contaminants.
For long-lived waste constituents, it also means that little dilution of the plume may occur.
The hydraulic conductivity of aquifers is sometimes reported as a transmissivity value, which is
usually denoted with the symbol T. Transmissivity is simply the product of hydraulic
conductivity and saturated thickness. To back-calculate the hydraulic conductivity, you should
divide the transmissivity by the value of the saturated zone thickness. The hydraulic conductivity
parameter in IWEM must be entered in meters per year.
The default value of hydraulic conductivity in IWEM varies with the subsurface environment you
have selected. If you selected the "unknown" subsurface environment, IWEM will use a
nationwide average value of 1,890 m/yr. If you selected one of the twelve hydrogeologic
environments and the hydraulic conductivity as "unknown," IWEM will treat the hydraulic
conductivity as a Monte-Carlo variable, and it will use a distribution of values that is appropriate
for the selected subsurface environment.
Regional Hydraulic Gradient (m/m). For unconfined aquifers, the hydraulic gradient is simply
the slope of the water table in a particular direction. It is calculated as the difference in the
elevation of the water table measured at two locations divided by the distance between the two
locations. In IWEM, this parameter represents the average horizontal ground water gradient in
the vicinity of the source. The gradient is meant to represent the natural ground water gradient as
it is, or would be, without influence from the source. The presence of a WMU, particularly a
surface impoundment, or a structural fill or roadway may cause local mounding of the water table
and associated higher local ground water gradients. IWEM assumes that the gradient value you
have entered does not include mounding; rather the software will calculate the predicted impact
on the ground water due to infiltration as part of the modeling evaluation.
For the same reasons as discussed above, assigning a low hydraulic gradient value will not
necessarily result in lower estimated ground water exposures. The hydraulic gradient is a unitless
parameter. Its default value depends on the subsurface environment you selected. If you selected
the "unknown" environment, IWEM will use a nationwide average value of 0.0057. If you
selected one of the 12 subsurface environments and did not specify the hydraulic gradient, IWEM
will treat the hydraulic gradient as a Monte-Carlo variable, and it will use a distribution of values
that is appropriate for the selected subsurface environment.
Aquifer Thickness (m). This parameter represents the vertical distance from the water table
down to the base of the aquifer, as shown in the diagram in Figure 4-2. Usually the base is an
impermeable layer, e.g., bedrock. This parameter is used to describe the thickness of the ground
water zone over which the leachate plume can mix with ground water. If your site has a highly
stratified hydrogeology, it may be difficult to precisely define the "base of the aquifer," but in
such cases, the stratification may effectively limit the vertical plume travel distance. In this case
it may be appropriate to enter the maximum vertical extent of the plume as an "effective"
saturated zone thickness in IWEM.
The parameter must be entered in meters. To convert from other units to meters, use the factors
given in Section 4.2.1. The default saturated zone thickness is a function of the selected
subsurface environment. If you selected the "unknown" subsurface environment, IWEM will use
the national average of 10.1 m. If you selected one of the 12 subsurface environments and did not
specify the saturated thickness, IWEM will treat the depth to the saturated thickness as a Monte-
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Carlo variable and use a distribution of values that is appropriate for the selected subsurface
environment.
4.3.2 Hydrologic (Infiltration and Recharge) Parameters
In IWEM, the infiltration rate for WMUs and structural fills is defined as the rate
(annual volume divided by source area) at which leachate flows from the bottom of
the source (including any liner for WMUs) into the unsaturated zone beneath the source For
roadways, infiltration rate refers to water exiting from the bottom layer of the roadway, usually
the subgrade layer, into the soils below. Recharge is the regional rate of aquifer recharge outside
of the source. Infiltration is determined a bit differently for different types of sources:
• For land application units, waste piles, landfills and structural fills, the infiltration
rate is primarily determined by the local climatic conditions, especially annual
precipitation, and for WMUs, liner characteristics.
• For surface impoundments, the infiltration rate from the unit is a function of the
impoundment ponding depth, liner characteristics, and the presence of a sludge layer at
the bottom of the impoundment. The regional recharge rate is a function of the annual
precipitation rate, and varies with geographical location and soil type.
• For roadways, infiltration is governed by pavement configuration, pavement hydraulic
properties, climatic conditions, and drainage system.
Table 4-6 summarizes the infiltration inputs. Infiltration rate is among the most sensitive site-
specific parameters in an IWEM evaluation, and, therefore, the software gives you the option to
provide a site-specific value. The model is usually much less sensitive to recharge rate. IWEM
determines the appropriate value for you, as a function of site location and soil type.
Climate Center. IWEM includes a database of infiltration rates and regional recharge rates for
102 climate centers located throughout the United States. To ensure that IWEM will use the most
appropriate values (if you choose to let IWEM select a default value), you must select the climate
center which is most appropriate for your site. Usually this is the nearest climate center.
However, this is not always the case. Especially in coastal and mountain regions, the nearest
climate center does not always represent conditions that most closely approximate conditions at
your site. You should therefore use your judgment and also consider other adjacent climate
centers. In the IWEM software tool, you select the climate center from a drop-down list which
can be sorted by city or by state. Figure 4-9 shows the geographic locations of the 102 climate
stations in the United States.
Runoff Rate (m/yr), Precipitation Rate (m/yr), and Evaporation Rate (m/yr). These inputs
specific to roadways with ditches and should be specified in conjunction with infiltration rates so
that they represent consistent climatic conditions. See discussion below under Site-
Specific Infiltration Rate. Values for representative climate centers and materials for
runoff rate are provided in Tables 6-21 through 6-23 of Section 6.4.3.2 of the
Technical Background Document in units of m/yr. Table 6-16 in the same section
provides 5-year average precipitation rates in m/yr, and Tables 6-24 and 6-25 provide
evaporation rates from embankments and pans correlated with climate centers, also in m/yr.
IWEM requires units of m/yr for all three parameters.
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Table 4-6. IWEM Input Parameters: Hydrologic (Infiltration and Recharge) Parameters
Parameter
Applicable
Source
Tvoe
Units
Default Value if No
User Input
Allowable Range
Minimum
Maximum
Required Inputs
Nearest Climate Center
Infiltration Rate
All
Roadway
-
m/yr
NA
NA
NA
0
NA
10
Required Inputs if Ditch is Defined
Runoff rate
Precipitation rate
Evaporation rate
Roadway
Roadway
Roadway
m/yr
m/yr
m/yr
NA
NA
NA
0
0
0
10
10
10
Optional Inputs
Regional Soil Type
(Select from list)
Waste Type Permeability
Infiltration Rate
All
WP
AIIWMUs,
Structural
Fill
-
m/yr
Chosen randomly
from course-,
medium-, or fine-
grained
Chosen randomly
from low, medium, or
high
Assigned from the
IWEM database
according to the
selected climate
station, soil type or
waste type
NA
NA
0
NA
NA
10
NA = Not Applicable
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Alaska
Hawdi
Puerto Rico
Figure 4-9. Locations of IWEM climate stations.
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Regional Soil Type. To assign an appropriate recharge rate, IWEM needs to know the dominant,
regional soil type near your site. IWEM provides a selection of three major soil types, which are
representative of most soils in the United States:
Sandy Loam
• Silty Loam
• Silty Clay Loam.
IWEM also allows you to select the soil type "unknown." In that case, IWEM will treat the soil
type as a Monte-Carlo variable and randomly select from the three available soil types, in
accordance with the relative frequency of occurrence of each type across the United States. By
selecting the soil type, IWEM also assigns the soil parameters that are used in the modeling of
fate and transport in the unsaturated zone of the aquifer.
Waste Type Permeability. This parameter is used only for waste piles. Waste piles are not
typically covered and the permeability of the waste itself is a factor in determining the rate of
leachate released due to water percolating through the WMU. For waste piles, IWEM recognizes
three categories of waste permeability and their associated infiltration rate: high permeability
(0.041 cm/sec); moderate permeability (0.0041 cm/sec); and low permeability (0.00005 cm/sec).
The waste permeability is correlated with the grain size of the waste material, ranging from
coarse to five-grained materials.
If you do not specify the waste type for waste piles, IWEM will default to randomly selecting
between the infiltration rates for each of the three waste types in the Monte Carlo process, with
each type having equal probability. That is, IWEM will use a uniform probability distribution.
Site-specific Infiltration Rate (m/yr). This parameter represents the actual annual volume of
leachate, per unit area of the source, that flows from the bottom of the source into the unsaturated
zone underneath.
For WMUs, the performance characteristics of a liner, if present, are among the
most important factors controlling the infiltration rate, and therefore, the rate of
leachate release. IWEM provides you the option to enter a site- specific infiltration Sec. 6.4.1
rate to accommodate liner designs that are different from the standard liner
designs (i.e., (1) no liner, (2) single clay liner, or (3) composite liner), and to evaluate extreme
climatic conditions. IWEM provides default values for infiltration rate, which are a function of
WMU type, liner design, and site location. These values are used as defaults. The default
infiltration rates used in IWEM for landfills, waste piles, and land application units were
developed using the Hydrologic Evaluation of Landfill Performance (HELP) model (Schroeder
et. al., 1994). The infiltration rate from a WMU is difficult to measure directly; if you wish to
determine site-specific WMU infiltration rates for use in IWEM, it is recommended to use a
model such as HELP to estimate the rates.
For structural fills, infiltration is handled as for WMUs, but with no liner. [iBD
For roadways, subgrade infiltration is governed by pavement configuration, Sec 6 4 1 2
pavement hydraulic properties, climatic conditions, and drainage system.
Nationwide, a multitude of combinations of those four factors are possible. At present, there are
very little subgrade infiltration data. Section 6.4.3.2, Tables 6-18 through 6-20 of the Technical
Background Document, presents some representative values correlated to climate center and
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TBD
pavement type. A procedure for estimating subgrade infiltration for different
configurations, conditions, and settings is presented in Appendix E of the
Technical Background Document. The procedure involves dividing the United
States into 12 climatic zones. For each zone, pre-determined infiltration rates for e^ E
major types of pavement configuration with a range of material properties and
climatic conditions are given. If the roadway has a subsurface drainage system, please refer to
those parts of the Technical Background Document for guidance on how to modify the selected
default value. However, the Agency highly recommends consulting with a knowledgeable
highway engineer/designer prior to determining a drainage system correction factor or a user-
specified rate, in general. As a note, shoulders and embankments do not generally have
subsurface drainage component systems
The infiltration rate in IWEM must be entered in units of meter/year.
4.4 Waste Constituents and Constituent Parameters
Constituent parameters are divided into three tabs: constituent selection and leachate/waste
concentrations, chemical properties(e.g., sorption parameters, hydrolysis rate constants), and
reference ground water exposure concentrations. The following sections discuss the IWEM
constituent parameters.
4.4.1 Constituent Selection and Concentrations
Constituents are identified in IWEM by either constituent name or CAS number.
Whereas constituents may have multiple names, the CAS number is an industry-
standard, unique, identification code. If you want to use the "Add New
Constituent" option to assign different fate and transport parameters to an
existing IWEM constituent, it is recommended to use the actual CAS number and
enter a new constituent name.
Sec. 6.1.2
Sec. 6.2.2
Sec. 6.3.9
Table 4-7 lists the parameters needed to specify constituent concentrations.
Table 4-7. IWEM Input Parameters: Constituent Source Concentration Parameters
Parameter
Leachate concentration (All sources)
Total concentration (Structural Fill and
Roadway only)
Units
mg/L
mg/kg
Required
User
Input?
yes
yes
Default
Value if
No User
Input
NA
NA
Allowable Range
Minimum
>0
>0
Maximum
1,000
1,000
Constituent Initial Concentration in Leachate (mg/L). You must provide the leachate
concentration for each selected waste constituent that you expect in the leachate that will
infiltrate into the soil underneath a source. For WMUs, this will be a single concentration for
each constituent. For a roadway source, you must specify the leachate concentration of each
selected constituent for each strip and layer. Note that IWEM does not allow the use of teachable
materials in ditches, so you will not be able to enter leachate concentrations for strips designated
as ditches.
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EPA has developed a number of tests to measure the leaching potential of different wastes and
waste constituents in the laboratory. These include the Toxicity Characteristic Leaching
Procedure (TCLP) and the Synthetic Precipitation Leaching Procedure (SPLP). Consult
Chapter 2 of the Guide (Characterizing Waste) for analytical procedures that can be used to
determine expected leachate concentrations for waste constituents.
Recently, new leaching test methods, EPA SW-846 Methods 1313, 1314, 1315, and 13161, were
developed to support the evaluation of coal combustion residual materials. Leaching test results
acquired from these new methods were also recently used in probabilistic fate and transport
modeling of managed coal combustion wastes. These materials are typical materials used as
adjuncts in roadways. These leaching methods are part of the Leaching Environmental
Assessment Framework (LEAF) developed by a collaborative research effort between the U.S.
EPA, Vanderbilt University, and Dutch and Danish partners (Kosson et al, 2002; U.S. EPA,
2010).
Constituent Initial Concentration of Total Leachable Mass (mg/kg). For structural fill and
roadway sources, you must also specify total concentration of each selected constituent in the
material used for the fill, or for roadways, each strip and layer. For roadways, you are only
required to input both leachate and total concentrations for one layer in one strip.
Input values for source constituent parameters for recycled structural fill and roadway materials
(i.e., leachate concentration and total teachable mass concentration) can be obtained from
empirical testing data or field data. In practice, the producer of an industrial material would be
the most likely resource for obtaining this data through engineering and environmental testing,
both in the laboratory and in the field. The Recycled Materials Resource Center (RMRC;
http://rmrc.wise.edu/), a federal university—partnered research and outreach facility for the
highway community, has developed the User Guidelines for Byproducts and Secondary Use
Materials in Pavement Construction, available online.2 The online guidance document provides
detailed information on many industrial materials commonly used in roadway and some
structural fill construction.
4.4.2 Physical-Chemical Properties
IWEM includes a built-in database with chemical properties data on 206 organic
constituents and 22 metals (25 for roadway module). Appendix A provides a list of
these constituents. (The default chemical properties are provided in Appendix B of
the Technical Background Document} To preserve the integrity of the database,
IWEM gives you limited flexibility to modify these data. However, IWEM does give you the
option of overriding some of those properties with user-specified values (see discussion below).
IWEM also allows you to add new constituents to its database, which provides an indirect
mechanism for assigning different constituent property values: by entering a constituent of
interest as a new constituent in the database, you can assign it different parameter values.
The physical and constituent properties that affect subsurface fate and transport include sorption
parameters and degradation parameters. These inputs are somewhat different for organics and
metals; they are summarized in Table 4-8 and discussed below.
1 http://www.epa.gov/epawaste/hazard/testmethods/sw846/new meth.htm
2 http://rmrc.wisc.edu/user-guidelines-2/
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Table 4-8. IWEM Input Parameters: Chemical Properties Parameters
Parameter
Units
Required
User
Input?
Default Value if No User Input
Allowable Range
Minimum
Maximum
Organ/as
Partitioning coefficient (Kd)
Overall Decay Coefficient
L/kg
1/yr
-
"
Koc from database
Hydrolysis rate constants (acid,
neutral, and base) from
database
0
0
1E+6
10
Metals
Partitioning coefficient (Kd)
L/kg
-
MINTEQ isotherm from
database
0
1E+6
4.4.2.1 Organ ics
For organics, the IWEM database contains values for octanol-water partitioning coefficient (Koc)
and three hydrolysis constants (acid, neutral, and base). You can override these by specifying
values for the following related inputs:
• a constituent partitioning coefficient (Kd), which overrides the octanol-water portioning
coefficient (Koc) in the database (see discussion below)
• an overall constituent decay rate, which overrides the hydrolysis rates in the database and
can include other forms of degradations, such as biodegradation.
Partitioning Coefficient (Koc or Kd) (L/kg). These_parameters describe sorption, or the affinity
of a constituent to attach itself to soil and aquifer grains. Koc is applicable only to organic
constituents, which tend to sorb onto the organic matter in soil or in an aquifer. Constituents with
high Koc values tend to move more slowly through the soil and ground water. Volatile organics
tend to have low Koc values, whereas semi-volatile organics often have high Koc values. Koc
values can be obtained from many constituent property handbooks, as well as online databases,
(e.g., Handbook of Environmental Data on Organic Constituents, Verschueren, 1983).
Sometimes, these references provide an octanol-water partition coefficient (Kow), rather than a
Koc value. Kow and Koc are roughly equivalent parameters. A number of conversion formulas
exist to convert Kow values into Koc, and can be found in handbooks on environmental fate data
(e.g., Verschueren, 1983; Kollig et. al., 1993). Different conversion formulas exist for different
constituents and environmental media, and there is no single formula that is valid for all organic
constituents; therefore, they should be used with some caution.
You can enter a Kd for IWEM to use instead of the Koc. For organics, Kd is derived
from Koc by multiplying Koc by the fraction organic carbon (foc) in the waste. Thus,
if you provide a Kd for an organic, it is used directly; if you elect to use the default Sec 6 6 2
Koc from the database, IWEM converts it to Kd using the foc. See Section 6.6.2 of the Technical
Background Document for more details.
In IWEM, Koc and Kd have units of L/kg or, equivalently, mL/g.
Hydrolysis or Overall Decay Rate Constants. Hydrolysis refers to the transformation of
constituent constituents through reactions with water. For organic constituents, hydrolysis can be
one of the main degradation processes that occur in soil and ground water. The hydrolysis rate
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IWEM User's Guide Understanding Your IWEM Input Values
values that are part of the IWEM database have been compiled by the U.S. EPA Office of
Research and Development (Kollig, 1993). For each organic constituent, the database includes
three hydrolysis rate constants: an acid-catalyzed rate constant, a neutral rate constant, and a
base-catalyzed rate constant. However, other transformation processes can occur, such as
biodegradation, and these processes are not considered in IWEM, nor are rate constants for them
included in the constituent database. Biodegradation can be a significant attenuation process for
organic constituents in the subsurface. However, this process is also highly site- and constituent-
specific. It is not possible to provide reliable default biodegradation rates to be used in IWEM.
If you want to account for biodegradation or other transformation processes, you can enter a first-
order constituent-specific overall decay rate (combining hydrolysis, biodegradation, and any
other processes you wish to include). IWEM will use this rate instead of the hydrolysis rates in
the database. This decay coefficient has units of 1/yr. The value of the decay coefficient is related
to half-life as
Decay Coefficient (1/yr) = 0.693 / Half-life (yr)
IWEM stores user-defined decay coefficients in its constituent property database. You should,
however, be careful in using a decay coefficient value which is appropriate for one site and not
appropriate for others. Evidence of the significance of biodegradation should be carefully
considered in accordance with EPA guidance, such as the OSWER Directive 9200.4-17P on Use
of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground
Storage Tank Sites. A compendium of EPA bioremediation documents is available online at
www.epa.gov/ORDAVebPubs/biorem.html.
4.4.2.2 Metals
Metals Kd Isotherm Data. In the case of metals, sorption is expressed in the partition
coefficient Kd. KdS for metals can vary significantly with ground water pH and other
geochemical conditions. Thus, rather than using a single Kd value for each metal constituent,
IWEM includes multiple sets of Kd values for each metal calculated using the MINTEQA2
geoconstituent speciation model to reflect the impact of variations in those conditions. Each set
of Kd values is referred to as a sorption isotherm. The sorption parameters for metals in IWEM
are part of the built-in database and they cannot be modified by the user. However, you can elect
to use a different set of isotherms developed for coal combustion residuals by specifying waste
type (ash, ash and coal, FGD, or FBC) and leachate pH. You can also specify a single Kd to use
instead of the isotherms.
Further information on how the MINTEQ sorption isotherms were developed can
be found in the Technical Background Document (Section 6.6.2.2) and the
EPACMTP Parameters/Data Background Document (U.S. EPA, 2003b). Sec 6 6 2 2
If you are adding a new constituent to the IWEM database, you can enter a single Kd value to
model sorption for the constituent. The Kd must be entered in units of L/kg or, equivalently,
mL/g.
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TBD
4.4.3 Reference Ground Water Concentrations
The final set of constituent-specific parameters used by IWEM is RGCs, which
reflect not-to-exceed exposure levels for drinking water ingestion, shower inhalation,
and shower/bath dermal cancer risks and non-cancer hazards. RGCs include
regulatory MCLs, other regulatory standards, and HBNs. Table 4-9 summarizes the RGCs used
by IWEM, and they are discussed in more detail below.
Table 4-9. IWEM Input Parameters: Reference Ground Water Concentrations
Sec. 7
Parameter
MCL
Other Standard
User-Specified HBN
Exposure Duration Associated with HBN
Units
mg/L
mg/L
mg/L
yrs
Provided in IWEM
Database?
Yes, for 59 constituents
No
No
No
Allowable Range
Minimum
>0
>0
>0
>0
Maximum
NA
NA
NA
70
NA = Not Applicable
Note that only MCLs are provided in the database, and those are available for only 59 of the 231
constituents in the database. Thus, for constituents without an MCL, you will have to provide
either an alternative regulatory standard or at least one HBN and associated exposure duration.
Similarly, if you add a constituent to the database, you will have to provide at least one of these
RGCs. IWEM imposes no restrictions on user-specified RGCs, other than that they should be
expressed in units of mg/L. User-specified RGCs may represent either more or less stringent
health-based values, or alternative regulatory standards. IWEM makes no assumptions about
user-specified RGCs and, consequently, the software cannot check whether your value is correct
or not.
Maximum Contaminant Level (MCL) (mg/L). Maximum Contaminant Levels (MCLs) are
provided in IWEM for the 59 IWEM constituents for which values are currently available.
MCLs are maximum constituent concentrations allowed in public drinking water and are
established under the Safe Drinking Water Act. For each contaminant to be regulated, EPA first
sets a Maximum Contaminant Level Goal (MCLG) at a level that protects against health risks.
EPA then sets each contaminant's MCL as close to its MCLG as feasible, taking costs and
available analytical and treatment technologies into consideration. MCLs in the database cannot
be changed. However, you can enter an alternative regulatory standard (see below).
Other Standards (mg/L). You may enter an alternative constituent-specific regulatory standard,
such as a state regulatory standard, and IWEM will use it instead of the MCL. Alternative
regulatory standards must be in units of mg/L.
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User-Specified Health-Based Number (HBN) (mg/L). HBNs are the maximum constituent
concentrations in ground water that would generally be expected not to cause adverse noncancer
health effects in the general population (including sensitive subgroups), or not to result in an
additional incidence of cancer in more than some specified fraction of (e.g., individuals exposed to
the constituent (e.g., one in one million) via either ingestion, inhalation, or dermal pathways.
HBNs are not provided in the IWEM database, but you can enter the following types of user-
specified HBNs for use in an IWEM evaluation:
• Ingestion, cancer
• Ingestion, noncancer
• Inhalation, cancer
• Inhalation, noncancer
• Dermal, cancer
• Dermal, noncancer.
The best source of HBNs is the Regional Screening Level (RSL) Generic Tables PrBD
fU.S. EPA. 2015b\ which provide HBNs for more than 700 chemicals under six U=A=s
(U.S. EPA, 2015b), which provide HBNs for more than 700 chemicals under six
scenarios. Consult the Technical Background Document (Section 7.2) for further Sec 7 2
details on obtaining HBN values from this source.
Exposure Duration (yrs). For each HBN you enter, you must also enter an associated exposure
duration (in years) that is consistent with the way the RGC was derived.
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6. References
Chow, V.T. 1959. Open-Channel Hydraulics. New York: McGraw-Hill.
Kollig, H. 1993. Environmental Fate Constants for Organic Chemicals under Consideration for
EPA's Hazardous Waste Identification Projects. Report No. EPA/600/R-93/132.
Environmental Research Laboratory, Athens, GA 30605.
Kosson, D.S., 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 79(3): 159-204. Available online at
www.niehs.nih.gov/news/assets/docs_a_e/an_integrated_framework_for_evaluating_leac
hing_in_waste_management_and_utilization_of_secondary_materials_508.pdf
Schroeder, P.R., Dozier, T.S., Zappi, P.A., McEnroe, B.M., Sjostrom, J.W., and Peyton, R.L.,
1994. The Hydrologic Evaluation of Landfill Performance (HELP) Model, Engineering
Document for Version 3. Risk Reduction Engineering Laboratory, Office of Research and
Development, U.S. EPA, Cincinnati, OH 45268, EPA/600/R-94/168b.
U.S. EPA (Environmental Protection Agency). 1991.MNTEQA2/PRODEFA2, A Geochemical
Assessment Modelfor Environmental Systems: Version 3.0 User's Manual. EPA/600/3-
91/021, Office of Research and Development, Athens, Georgia 30605.
U.S. EPA (Environmental Protection Agency). 1997. Guiding Principles for Monte Carlo
Analysis. EP A/63 O/R-97/1001 Risk Assessment Forum, Washington, DC 20460.
U.S. EPA (Environmental Protection Agency). 1999. A Framework for Finite-Source
Multimedia, Multipathway, and Multireceptor Risk Assessment—3MRA. U.S. EPA,
Office of Solid Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 2002a. Industrial Waste Management Evaluation
Model (IWEM) Technical Background Document. EPA530-R-02-012. Office of Solid
Waste and Emergency Response, Washington, DC. August, http://www.epa.gov/
epawaste/nonhaz/industrial/tools/iwem/index.htm.
U.S. EPA (Environmental Protection Agency). 2002b. Industrial Waste Management Evaluation
Model (IWEM) User's Guide. EPA530-R-02-013. Office of Solid Waste and Emergency
Response, Washington, DC. August. Available at http://www.epa.gov/epawaste/
nonhaz/industrial/tools/iwem/index.htm.
U.S. EPA (Environmental Protection Agency). 2002c. Guide for Industrial Waste Management.
Office of Solid Waste, Washington, DC. http://www.epa.gov/epawaste/nonhaz/industrial/
guide/index.htm.
U.S. EPA (Environmental Protection Agency). 2003a. EPA's Composite Model for Leachate
Migration with Transformation Products (EPACMTP): Technical Background Document.
U.S. EPA, Office of Solid Waste, EPA530-R-03-002, April.
U.S. EPA (Environmental Protection Agency). 2003b. EPA's Composite Model for Leachate
Migration with Transformation Products (EPACMTP): Parameter/Data Background
Document. U.S. EPA, Office of Solid Waste, EPA530-R-03-003, April.
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IWEM User's Guide References
U.S. EPA (Environmental Protection Agency). 2003c. EPA's Composite Model for Leachate
Migration with Transformation Products (EPACMTP): Draft Addendum to the Technical
Background Document. U.S. EPA, Office of Solid Waste. September.
U.S. EPA (Environmental Protection Agency). 2003d. EPA's Composite Model for Leachate
Migration with Transformation Products (EPACMTP): Draft Addendum to the
Parameter/Data Background Document. U.S. EPA, Office of Solid Waste. April.
U.S. EPA (Environmental Protection Agency). 2010. Background Information for the Leaching
Environmental Assessment Framework (LEAF) Test Methods_. EPA/600/R-10/170. U.S.
EPA, Washington, DC.
U.S. EPA (Environmental Protection Agency). 2015a. Industrial Waste Evaluation Model
(IWEM) v3.1 Technical Documentation. Final. Office of Resource Conservation and
Recovery, Washington DC.
U.S. EPA (Environmental Protection Agency). 2015b. Regional Screening Levels for Chemical
Contaminants at Superfund Sites: Regional Screening Levels Generic Tables. Developed
in cooperation with Oak Ridge National Laboratory. Available at http://www.epa.gov/
reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed
November 2013.
Verschueren, K., 1983. Handbook of Environmental Data on Organic Chemicals. VanNostrand
Reinhold Co., New York.
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IWEMUser's Guide
Appendix A: List of Waste Constituents
Appendix A: List of Waste Constituents
Organics (206)
83-32-9 Acenaphthene 107-05-1
75-07-0 Acetaldehyde [Ethanal] 218-01-9
67-64-1 Acetone (2-propanone) 108-39-4
75-05-8 Acetonitrile (methyl cyanide) 95-48-7
98-86-2 Acetophenone 106-44-5
107-02-8 Acrolein 1319-77-3
79-06-1 Acrylamide 98-82-8
79-10-7 Acrylic acid [propenoic acid] 108-93-0
107-13-1 Acrylonitrile 108-94-1
309-00-2 Aldrin 72-54-8
107-18-6 Allyl alcohol 72-55-9
62-53-3 Aniline (benzeneamine) 50-29-3
120-12-7 Anthracene 2303-16-4
56-55-3 Benz{a}anthracene 53-70-3
71-43-2 Benzene 96-12-8
92-87-5 Benzidine 95-50-1
50-32-8 Benzo{a}pyrene 106-46-7
205-99-2 Benzo{b}fluoranthene 91-94-1
100-51-6 Benzyl alcohol 75-71-8
100-44-7 Benzyl chloride 75-34-3
111-44-4 Bis(2-chloroethyl)ether 107-06-2
39638-32-9 Bis(2-chloroisopropyl)ether 156-59-2
117-81-7 Bis(2-ethylhexyl)phthalate 156-60-5
75-27-4 Bromodichloromethane 75-35-4
74-83-9 Bromomethane 120-83-2
106-99-0 Butadiene, 1, 3- 94-75-7
71-36-3 Butanol 78-87-5
85-68-7 Butyl benzyl phthalate 542-75-6
88-85-7 Butyl-4,6-dinitrophenol,2-sec-(Dinoseb) 10061-01-5
75-15-0 Carbon disulfide 10061-02-6
56-23-5 Carbon tetrachloride 60-57-1
57-74-9 Chlordane 84-66-2
126-99-8 Chloro-1,3-butadiene 2-(Chloroprene) 56-53-1
106-47-8 Chloroaniline p- 60-51-5
108-90-7 Chlorobenzene 119-90-4
510-15-6 Chlorobenzilate 68-12-2
124-48-1 Chlorodibromomethane 57-97-6
75-00-3 Chloroethane [Ethyl chloride] 119-93-7
67-66-3 Chloroform 105-67-9
74-87-3 Chloromethane 84-74-2
95-57-8 Chlorophenol 2- 99-65-0
Chloropropene, 3- (Allyl Chloride)
Chrysene
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT, p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane1,2-
Dichlorobenzene1,2-
Dichlorobenzenel ,4-
Dichlorobenzidine3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane1,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans-1,2-
Dichloroethylene1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropene trans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
A-l
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IWEMUser's Guide
Appendix A: List of Waste Constituents
51-28-5 Dinitrophenol 2,4- 126-98-7
121-14-2 Dinitrotoluene 2,4- 67-56-1
606-20-2 Dinitrotoluene 2,6- 72-43-5
117-84-0 Di-n-octyl phthalate 109-86-4
123-91-1 Dioxane1,4- 110-49-6
122-39-4 Diphenylamine 78-93-3
122-66-7 Diphenylhydrazine, 1,2- 108-10-1
298-04-4 Disulfoton 80-62-6
115-29-7 Endosulfan (Endosulfan I, II, mixture) 298-00-0
72-20-8 Endrin 1634-04-4
106-89-8 Epichlorohydrin 56-49-5
106-88-7 Epoxybutane, 1,2- 74-95-3
110-80-5 Ethoxyethanol 2- 75-09-2
111-15-9 Ethoxyethanol acetate, 2- 91-20-3
141-78-6 Ethyl acetate 98-95-3
60-29-7 Ethyl ether 79-46-9
97-63-2 Ethyl methacrylate 55-18-5
62-50-0 Ethyl methanesulfonate 62-75-9
100-41-4 Ethylbenzene 924-16-3
106-93-4 Ethylene dibromide (1,2-dibromoethane) 621-64-7
107-21-1 Ethylene glycol 86-30-6
75-21-8 Ethylene oxide 10595-95-6
96-45-7 Ethylene thiourea 100-75-4
206-44-0 Fluoranthene 930-55-2
50-00-0 Formaldehyde 152-16-9
64-18-6 Formic acid 56-38-2
98-01-1 Furfural 608-93-5
58-89-9 HCH(Lindane) gamma- 30402-15-4
319-84-6 HCH alpha- 36088-22-9
319-85-7 HCH beta- 82-68-8
75-44-8 Heptachlor 87-86-5
1024-57-3 Heptachlor epoxide 108-95-2
87-68-3 Hexachloro-1,3-butadiene 62-38-4
118-74-1 Hexachlorobenzene 108-45-2
77-47-4 Hexachlorocyclopentadiene 298-02-2
55684-94-1 Hexachlorodibenzofurans [HxCDFs] 85-44-9
34465-46-8 Hexachlorodibenzo-p-dioxins [HxCDDs] 1336-36-3
67-72-1 Hexachloroethane 23950-58-5
70-30-4 Hexachlorophene 75-56-9
110-54-3 Hexanen- 129-00-0
7783-06-4 Hydrogen Sulfide 110-86-1
193-39-5 lndeno{1,2,3-cd}pyrene 94-59-7
78-83-1 Isobutyl alcohol 57-24-9
78-59-1 Isophorone 100-42-5
143-50-0 Kepone 95-94-3
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol 2-
Methoxyethanol acetate 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Naphthalene
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
A-2
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IWEMUser's Guide
Appendix A: List of Waste Constituents
51207-31-9 Tetrachlorodibenzofuran, 2,3,7,8- 79-00-5
1746-01-6 Tetrachlorodibenzo-p-dioxin, 2,3,7,8- 79-01-6
630-20-6 Tetrachloroethane 1,1,1,2- 75-69-4
79-34-5 Tetrachloroethane 1,1,2,2- 95-95-4
127-18-4 Tetrachloroethylene 88-06-2
58-90-2 Tetrachlorophenol 2,3,4,6- 93-72-1
3689-24-5 Tetraethyl dithiopyrophosphate (Sulfotep) 93-76-5
137-26-8 Thiram [Thiuram] 96-18-4
108-88-3 Toluene 121-44-8
95-80-7 Toluenediamine 2,4- 99-35-4
95-53-4 Toluidineo- 126-72-7
106-49-0 Toluidinep- 108-05-4
8001-35-2 Toxaphene (chlorinated camphenes) 75-01-4
75-25-2 Tribromomethane (Bromoform) 108-38-3
76-13-1 Trichloro-1,2,2-trifluoro- ethane 1,1,2- 95-47-6
120-82-1 Trichlorobenzene 1,2,4- 106-42-3
71-55-6 Trichloroethane 1,1,1- 1330-20-7
Trichloroethane 1,1,2-
Trichloroethylene
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene
Tris(2,3-dibromopropyl)phosphate
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Metals (25)
7429-90-5 Aluminum (CCR waste only-Roadway)
7440-36-0 Antimony
22569-72-8 Arsenic (III)
15584-04-0 Arsenic (V)
7440-39-3 Barium
7440-41-7 Beryllium
7440-42-8 Boron (CCR waste only-Roadway)
7440-43-9 Cadmium
16065-83-1 Chromium (III)
18540-29-9 Chromium (VI)
7440-48-4 Cobalt
7440-50-8 Copper
16984-48-8 Fluoride
7439-89-6 Iron (CCR waste only-Roadway)
7439-92-1 Lead
7439-96-5 Manganese
7439-97-6 Mercury
7439-98-7 Molybdenum
7440-02-0 Nickel
10026-03-6 Selenium (IV)
7782-49-2 Selenium (VI)
7440-22-4 Silver
7440-28-0 Thallium
7440-62-2 Vanadium
7440-66-6 Zinc
A-3
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IWEM User's Guide Appendix A: List of Waste Constituents
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A-4
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IWEM User's Guide Appendix B: Example Problems for WMU Evaluation
Appendix B: Example Problems for WMU Evaluation
The purpose of this section is to provide the user examples on how to properly set up an IWEM
evaluation for WMUs and execute the simulation. These examples are hypothetical scenarios to
serve as tutorial; therefore, the user is cautioned from misconstruing both the scenarios and the
results as real-life case studies. Project files corresponding to this example may be found in either
• C :\Users\Public\Documents\IWEM\SampleData\ Appendix_B_WMU or
• C :\Users\[your user name]\Documents\IWEM\SampleData\ Appendix_B_WMU.
B. 1 Land Application of Spent Foundry Sand in Home Gardens
Spent foundry sands are ideal for manufactured soils because of their uniformity, consistency,
and dark color in the case of green sands. The sands can be blended with soils and/or organic
amendments (e.g., peat, composted yard waste, manures, biosolids) to develop manufactured
soils suitable for horticultural, landscaping, and turfgrass applications (Jing and Barnes, 1993;
Naystrom et al., 2004; Lindsay and Logan, 2005; all as cited in U.S. EPA, 2009). However, the
unencapsulated use of spent foundry sands is of particular concern because the application to
land poses the potential for human and ecological exposure to chemical constituents found in the
material. This example shows how IWEM can be used to evaluate the ground water impact from
the use of spent foundry sands in manufactured soils containing spent foundry sands by home
gardeners living in Madison, Wisconsin.
The following parameters were used within the model to define the use scenario:
• Source Type: land application unit (i.e., unconsolidated application to land)
• Source Parameters:
- Area: 4,047 m2 (i.e., 1 acre)
- Operating life: 40 years (default, determined to be long enough to ensure full
constituent leaching from waste amended soils)
- Distance to drinking water well: 150 m (arbitrary model default distance)
• Subsurface parameters were set to model defaults:
- Subsurface environment: Unknown
- Groundwater pH: 7
- Depth to water table: 5.18m (IWEM default for a shallow aquifer)
- Hydraulic conductivity: 1.89><103m/yr
- Regional hydraulic gradient: 0.0057 m/m
- Aquifer thickness: 10.1 m
• Infiltration parameters were set based on the common soil type in Madison, WI:
- Soil type: silt loam (medium grained soil)
- Climate center: Madison, WI
• Constituent List:
- Arsenic (V)
- Input leachate concentration: 0.015 mg/L. This concentration is the higher of the 95th
percentile leachate concentrations found by either Synthetic Precipitation Leaching
B-l
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IWEM User's Guide Appendix B: Example Problems for WMU Evaluation
Procedure (SPLP) or the American Society for Testing and Materials (ASTM)
leachate methods.
• Constituent Properties:
- Chemical-specific decay rate: NA for metals
- Soil-water partition coefficient: selected from isotherms generated by the
MTNTEQA2 geochemical speciation model
• Reference Ground Water Concentrations:
- MCL (Maximum Contaminant Level): 0.01 mg/L (provided in IWEM)
- Exposure duration: 1 yr.
This example results in a finding that land application is an appropriate management practice
under this scenario (i.e., the estimated ground water concentration of arsenic under this scenario
is below the MCL). The IWEM output report for this scenario is provided in Attachment B-l.
B.2 Landfill Example
In developing a landfill unit to dispose industrial waste material, IWEM can be used to assist a
unit manager or a design engineer to determine the most appropriate WMU design to minimize
or avoid adverse ground water impacts by evaluating one or more types of liners, the
hydrogeologic conditions of the site, and the toxicity and expected leachate concentrations of the
anticipated waste constituents. The software can help compare the ground water protection
afforded by various liner systems with the anticipated waste leachate concentrations, so that the
manager/engineer can determine the minimum recommended liner system that will be protective
of human health and ground water resources. The following example illustrates how IWEM can
be used to determine the most appropriate liner design.
The following parameters were used within the model to define the use scenario:
• Source Type: landfill
• Source Parameters:
- Depth of landfill: 6.5m
- Distance to drinking water well: 150 m (arbitrary model default distance)
- Area: 12,300 m2
- Depth of the base of the landfill below ground surface: 0 (model default).
• Subsurface parameters were set to model defaults:
- Subsurface environment: Sand and gravel
- Groundwater pH: default distribution
- Depth to water table: default distribution
- Hydraulic conductivity: default distribution
- Regional hydraulic gradient: default distribution
- Aquifer thickness: default distribution
• Infiltration parameters:
- Soil type: silt loam (medium grained soil)
- Climate center: Greensboro, NC
B-2
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IWEMUser's Guide
Appendix B: Example Problems for WMU Evaluation
These settings result in the following infiltration and recharge rates:
- Recharge rate: 0.326 m/yr
- No Liner: 0.326 m/yr
- Single Liner: 0.036 m/yr
- Composite Liner: distribution
Constituent List:
- Acrylonitrile
- Input leachate concentration: 0.1 mg/L
Constituent Properties:
- Koc: default value from database (0.815 L/kg)
- Chemical-specific decay rates: default values from database (Ka = 500 moH-yr"1,
Kn = 0 yr-1, Kb = 5,200 moH-yT1)
Reference Ground Water Concentrations: No MCLs are available for acrylonitrile or
its daughter products (acrylamide and acrylic acid). Thus, oral HBNs from the RSLs
(based on soil to tapwater, risk of 1 * 10"5 or HQ of 1) were used:
Constituent
Acrylonitrile
Acrylamide (daughter product)
Acrylic acid (daughter product)
Cancer
Oral
HBN
(mg/L)
0.0012
0.00043
Exposure
Duration
(yr)
70
70
Noncancer
Oral
HBN
(mg/L)
7.8
Exposure
Duration
(yr)
30
This example results in a liner recommendation of composite liner for this scenario, based on
concentrations of acrylonitrile and the daughter product acrylamide.The IWEM output report for
this scenario is provided in Attachment B-l.
B.3 References
Jing, J., and S. Barnes. 1993. Agricultural use of industrial by-products. Biocycle 3¥(ll):63-64.
Lindsay, B.J., and TJ. Logan. 2005. Agricultural reuse of foundry sand. Journal of Residuals
Science and Technology 2:3-12.
Naystrom, P., J. Lemkow, and J. Orkas. 2004. Waste foundry sand - a resource in composting
and soil production. Foundry Trade Journal 775(3615): 188-189
U.S. EPA (Environmental Protection Agency). 2009. Risk Assessment Spent Foundry Sands in
Soil-Related Applications - Peer Review Draft. U.S. Environmental Protection Agency,
Office of Resource Conservations and Recovery, Washington, DC.
B-3
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IWEM User's Guide Appendix B: Example Problems for WMU Evaluation
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B-4
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IWEM User's Guide Attachment B-l: Sample Reports from WMU Evaluation Example
Attachment B-1. Sample Reports from
WMU Evaluation Examples
Example Bl: Land Application of Spent Foundry Sand in Home Gardens B-l-3
Example B2: Landfill Example with Daughter Products B-l-7
B-l-1
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IWEM User's Guide Attachment B-l: Sample Reports from WMU Evaluation Example
[This page intentionally left blank.]
B-l-2
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IWEMUser's Guide
Sample Report for Example Bl, Land Application
.
Example B1. Land Application for Spend Foundry Sand in Home Gardens (page 1 of 3)
Evaluation Results
Recommendation: No Liner
Number of Flow and Transport Simulations: 10000
2/17/2014 11:01:17AM
Facility Type Land Application Unit
Facility name Spent Foundry Sands garden
Street address
City
State
Zip
Date of sample analysis 2/1 4/1 4
Name of user Jane Doe
Additional information Example 1
Land Application Unit Parameters
Parameter Value
Area of land application unit (mA2) [requires site specific value] 4047
Distance to well (m) 150
Operational life (yr) 40
Subsurface Parameters
Subsurface Environment Unknown
Parameter Value
Ground-water pH value (metals only) 7default
Depth to water table (m) 5.18default
Aquifer hydraulic conductivity (m/yr) 1890default
Regional hydraulic gradient 0.0057default
Aquifer thickness (m) 10.1default
Reference
measured
default
assumption
Reference
default
default
default
default
default
B-l-3
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IWEMUser's Guide
Sample Report for Example Bl, Land Application
Example B1. Land Application for Spend Foundry Sand in Home Gardens (page 2 of 3)
Regional Soil and Climate Parameters
Parameter
Soil Type
Climate Center
No Liner Infiltration Rate (m/yr)
Recharge Rate (m/yr)
Value
Medium-grained soil (silt loam)
Madison Wl
.0912
0.0912
Constituent Reference Groundwater Concentrations and Constituent Properties
Constituent Name
Arsenic (V)
RGC
(mg/L)
0.01
RGC Based On
MCL
Kd*(L/kg)
Decay Coeff*
(1/vr)
Leachate
Conc.(mq/L)
0.015
*lf a site-specific value was entered by the user, it will be displayed here; otherwise, the model used the constituent properties listed at the end of the report.
Detailed Results for Parent Constituents -- No Liner
Constituent Name
Arsenic (V)
Leachate
Cone. (rng/L)
0.015
DAF
(mg/L)
9.80E+08
Selected RGC
MCL
RGC
(mg/L)
0.01
90th %tile Exp.
Cone. (mg/L)
1.54E-11
Below
Benchmark?
Yes
B-l-4
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IWEMUser's Guide
Sample Report for Example Bl, Land Application
Example B1. Land Application for Spend Foundry Sand in Home Gardens (page 3 of 4)
Constituent Name
Arsenic (V)
CAS ID
15584-04-0
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Metal
74.9216
1.00E+06
Reference
CambridgeSoft Corporation, 2001
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
Value
0.01
Reference
USEPA, 2013
B-l-5
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IWEM User's Guide Sample Report for Example Bl, Land Application
Example B1. Land Application for Spend Foundry Sand in Home Gardens (page 4 of 4)
References
CambridgeSoft Corporation, 2001, ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July 2001.
B-l-6
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IWEMUser's Guide
Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 1 of 7)
2/17/2014 1:39:07PM
Evaluation Results
Recommendation: Composite Liner
Number of Flow and Transport Simulations: 10000
Facility Type Landfill
Facility name Sample landfill
Street address
City
State
Zip
Date of sample analysis 2/14/14
Name of user Jane Doe
Additional information Example 2
Landfill Parameters
Parameter Value
Depth of base of the LF below ground surface (m) G
Distance to well (m) 150
Landfill area (m"2) [requires site specific value] 1 .23E+04
WMU depth (m) [requires site specific value] 6.5
Subsurface Parameters
Subsurface Environment Sand and Gravel
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to water table (m) Distribution
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
default
default
measured
assumption
Reference
Monte Cario [See IWEM TBD 4.2.3. 1 ]
Monte Cario [See IWEM TBD 4.2,3. 1 ]
Monte Cario [See IWEM TBD 4.2.3.1]
Monte Cario (See IWEM TBD 4. 2.3 1 ]
Monte Cario [See IWEM TBD 4.2.3.1]
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IWEMUser's Guide
Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 2 of 7)
Regional Soil and Climate Parameters
Parameter
Soil Type
Climate Center
No Liner Infiftration Rate (m/yr)
Clay Liner Infiltration Rate (mtyr)
Composite Liner Infiltration Rate (mtyr)
Recharge Rate (ny/r)
Value
Medium-grained soil (silt loam)
Greensboro NC
.3256
.0362
Monte Carlo
0.3256
Constituent Reference Ground-water Concentrations and Constituent Properties
Constituent Name
Aciylonitrile
RGC
(mg/L)
0.0012
RGC Based On
HBN - Ingestion. Cancer
Kd* (L*g)
Decay Coeff*
(1/yr)
Laachate
Cone. (mg/L)
01
*lf a site-specific value was entered by the user, it will be displayed here; otherwise, the model used the constituent properties listed at the end of the report.
Daughter Constituent Reference Ground-water Concentrations and Constituent Properties
Parent Constituent
Acrylonitrile
Acrylonitrile
Daughter Constituent
Acryl amide
Acrylic acid [propenoic acid]
RGC
(mq/LI
0000*
7.8
RGC Based On
HBN - Irigestion, Cancer
HBN- Ingestion, NonCancer
Kd* (L/kg)
Decay Cosff.*
(1/yr)
*lf a site-specific value was entered by the user, it will be displayed here; otherwise, the model used the constituent properties listed at the end of the report.
Detailed Results for Parent Constituents — No Liner
Constituent Name
Acrylonitrile
Leachata
Cone. |mg/L)
0.1
DAF
Img/L)
1.8
Selected ROC
HBN - Ingestion, Cancer
RGC
(mg/L)
0.0004
90th "Atlle Exp.
Cone. (mg/L)
0.054?
Below
Benchmark?
No
Detailed Results for Parent Constituents— Clay Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mgyL)
0.1
DAF
(mg/L>
14
Selected RGC
HBN - Ingestion, Cancer
RGC
(mg/L)
0.0004
9Dth %tile Exp.
Cone. (mg/L)
0.0072
Below
Benchmark?
No
B-l-8
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IWEMUser's Guide
Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 3 of 7)
Detailed Results for Parent Constituents - Composite Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
1.60E+06
Selected RGC
HBN - Ingestion, Cancer
RGC
(mg/L)
0.0004
90th %tile Exp.
Cone. (mg/L)
6.17E-08
Below
Benchmark?
Yes
Detailed Results for Daughter Constituents - No Liner
Constituent Name
Acrylamide
Acrylic acid [propenoic acid]
Leachate
Cone. (mg/L)
0.134
0.1358
DAF
(mg/L)
2
1.8
Selected RGC
HBN - Ingestion, Cancer
HBN - Ingestion, NonCancer
RGC
(mg/L)
0.0004
7.8
90th %tile Exp.
Cone. (mg/L)
0.0682
0.0766
Below
Benchmark?
No
Yes
Detailed Results for Daughter Constituents - Clay Liner
Constituent Name
Acrylamide
Acrylic acid [propenoic acid]
Leachate
Cone. (mg/L)
0.134
0.1358
DAF
(mg/L)
19
NA
Selected RGC
HBN - Ingestion, Cancer
All Available
RGC
(mg/L)
0.0004
90th %tile Exp.
Cone. (mg/L)
0.007
NA
Below
Benchmark?
No
See No Liner
Detailed Results for Daughter Constituents - Composite Liner
Constituent Name
Acrylamide
Acrylic acid [propenoic acid]
Leachate
Cone. (mg/L)
0.134
0.1358
DAF
(mg/L)
1.00E+30
NA
Selected RGC
HBN - Ingestion, Cancer
All Available
RGC
(mg/L)
0.0004
90th %tile Exp.
Cone. (mg/L)
0
NA
Below
Benchmark?
Yes
See No Liner
B-l-9
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IWEMUser's Guide
Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 4 of 7)
Constituent Name
Acrylonitrile
CAS ID
107-13-1
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
53.0634
-0.089
500
0
5200
7.40E+04
360
0.0388
0.0001
Reference
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (rng/L)
Value
0.0012
Reference
RSLs, soil to tapwater, risk = 1e-5
B-l-10
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IWEMUser's Guide
Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 5 of 7)
Constituent Name
Acrylamide
CASIO
79-06-1
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (m^/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
71.0786
-0.989
31.5
0018
0
6.40E+05
337
0.0397
1.00E-09
Reference
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA. 2001 a
Calc., based on USEPA, 2001 a
USEPA. 1997C
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal. Non-Cancer (mg/L)
HBN-Dermal, Cancer (rng/L)
Value
0.0004
Reference
RSLs. soil to tapwater, risk = 1e-5
B-l-11
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IWEMUser's Guide
Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 6 of 7)
Constituent Name
Acrylic acid [propenoic acid]
CAS ID
79-10-7
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
72.1
-1.84
0
0
0
1.00E+06
325
0.0378
1.17E-07
Reference
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
Value
7.8
Reference
RSLs, soil to tapwater, HQ = 1
B-l-12
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IWEM User's Guide Sample Report for Example B2, Landfill
Example B2. Landfill Example with Daughter Products (page 7 of 7)
References
USEPA. 1993a. Environmental Fate Constants for Orgainic Chemicals Under Consideration for EPA's Hazardous Waste Identification Projects, EPA/600/R-93/132,
August 1993.
USEPA. 1997c. Superfund Chemical Data Matrix (SCDM). SCDMWIN 1,0 (SCDM Windows User's Version), Version 1. Office of Solid Waste and Emergency Response,
Washington DC: GPO. http://www.epa.gov/superfund/resources/scdm/index.htm. Accessed July 2001
USEPA. 2001 a. WATER9. Office of Air Quality Planning and Standards, Research Triangle Park, NC. http://www.epa.gov/ttn/chief/software/water/index.html. Accessed
July 2001.
B-l-13
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IWEM User's Guide Attachment B-l: Sample Report for Example B2, Landfill
[This page intentionally left blank.]
B-l-14
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Appendix C: Example Problems for Roadway Evaluation
Project files corresponding to this example may be found in either
• C:\Users\Public\Documents\IWEM\SampleData\Appendix_C_Roadway or
• C :\Users\[your user name]\DocumentsMWEM\SampleData\Appendix_C_Roadway.
C.1 Introduction
The following sections present five example problems applying IWEM Version 3.1 to three
actual sites and one hypothetical site:
• Example Cl: A 152-m test section of Wisconsin State Highway (WSH) 60 near Lodi,
WI
• Example C2: A 1,829-m section of Highway 57, northbound lane, between Waldo and
Random Lake, WI.
• Examples C3 and C4: Minnesota Road Research Facility (MnROAD), Low Volume
Road, near Monticello, MN.
• Example C5: A hypothetical road segment including ditches, drains, and gutters located
near Boston, MA.
The locations of the three actual sites are shown in Figure C-l. Each example includes a
description of the problem and available data, a discussion of how values for the required input
parameters were selected, screen shots of each IWEM screen showing the entered parameter
values, and a brief discussion of the results.
.
Blame ,•
o ]
MinneapolisO ^
Mankat-.
o Rocrtester W
Q
~ "I
:
?Fm_
OMifwaukee
Kenoshs *-mi'-r
Figure C-1. Map showing example sites: A-Lodi, WI; B-Waldo, WI; C-Monticello, MN
(map courtesy of Google Maps).
C-l
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
C.2 Example Problem 1 - Wisconsin State Highway 60, Lodi, Wl
A 152-m stretch of Wisconsin State Highway (WSH) 60 near Lodi, WI, was reconstructed
incorporating various types of industrial byproducts into the lowest structural layer, the subbase.
Multiple test sections were constructed using the following byproducts: foundry slag, foundry
sands, fly ash, and bottom ash. Each byproduct contains measurable amounts of cadmium and
selenium IV. The objective of this exercise is to determine if either cadmium or selenium present
in the foundry slag test section of WSH 60 are observed in the groundwater at a well at levels
higher than their respective MCLs, 5 ug/L and 50 ug/L, respectively, within a 10,000-year
timeframe. In other words, is the beneficial use of foundry slag appropriate?
This example demonstrates the use of the IWEM roadway module to perform a detailed analysis
using a combination of site-specific data and national data. This example is based upon data
collected by Craig Benson and Tuncer Edil of the University of Wisconsin in support of the
Wisconsin Department of Transportation (DOT).
The following subsections describe the inputs for this example, along with screen captures
showing the populated screens.
C.2.7 Source Parameters (Screens 6 and 7)
Figure C-2 shows the facility identification information for this example.
13 Input
Source Type (G)
Select Source Type
r Landfill
r Waste Pile
Source Parameters (7)
Subsurface Parameters
(~ Surface Impoundment
r Land Application Unit
•
Structural Fill
Lodi
Facility Identification Information
WSH 60 Foundry Slag Test Section
WSH 60
4/30/2007
EPA User
none
Figure C-2. Source Type (6).
C-2
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Table C-l provides the basic roadway geometry parameters, and Figure C-3 shows the layout.
The well is 30 m from the centerline of the roadway and located at approximately the middle of
the roadway segment. Groundwater flow is perpendicular to the roadway and flows in the
direction of the well. This orientation implies that the angle between the roadway and the
groundwater flow direction is 90°.
Table C-1. Roadway Geometry
Strip Type
Paved Area
Width (m)
10.4
Layers
4
Length (m)
152
Angle of flow
with respect to
roadway
Groundwater Flow
Direction
Figure C-3. Roadway schematic for WSH 60.
Figures C-4 and C-5 show Screen 7a and the well geometry portion of Screen 7 populated based
on the information provided above. Because the well is located along the line that bisects the
roadway (the green line in Figure C-4), either Region selection (Region I or Region IT) on
Screen 7a will work.
The receptor well distance D in IWEM (Figure C-5) is measured from the edge of the roadway;
however, the information provided is from the centerline of the roadway. Thus, you need to
subtract half the roadway width (10.4 m/2 = 5.2 m) from the given well distance from the
centerline (30 m - 5.2 m = 24.8 m).
The well is described as located at "approximately the middle of the roadway segment," so the
distance along the roadway from the midpoint (Figure C-5) is set to zero.
C-3
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Locatioi
We need to determine some basic relationships between the roadway, the direction of
groundwaterflow, and the location of the receptorwell. Consider an orientation where the
direction of groundwaterflow s left to right.
The angle between the r
The receptor well is in
• Well*
Angte/'V
n
aadway and the groundwaterflow is J0sto 90! T |
QK
Figure C-4. Location of Well with Respect to
Roadway (la).
Charge Well Geometry
Shortest distance between the
roadway edge and the
monitoring well (m): b_4Q
Distance along roadway from the point at which measurement
D was made to the midpoint of the roadway segment (point C in
the drawing) (m): r— • (Linthe drawing)
Angle between roadway and groundwaterflow (degrees): m(J
Figure C-5. Source Parameters (7) -Well
Geometry.
Figure C-6 shows the Geometry tab of the Source Parameters screen populated based on the
provided data.
Source Type (6)
J
Source Parameters (7)
L
Subsurface Paramete
This screen allows you to enter or change roadway parameters.
Number of roadway strips (include ditches in this count): |"l
Number of drains (applicable only when a ditch is present): lo Roadway segment length (m): |152
1
(5) Flow Characteristics
(A) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
ip numbers increase with distance from well (1 is closest).
Strip
> 1
Roadway Geometry
)# Strip Type Width (m) # of Layers
Paved Area 10.4 A
Figure C-6. Roadway Geometry (7).
C-4
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Table C-2 provides the layer properties, and Figure C-7 shows the Layers tab of the Source
Parameters screen populated based on these data. When entering layer data, remember that layer
1 is the bottom layer.
Table C-2. Layer Material Properties
Layer
1 - Foundry Slag Subbase
2 - Salvaged Asphalt Base
3 - Crushed Aggregate Base
4 - Asphalt Concrete
Thickness (m)
0.840
0.140
0.115
0.125
Hydraulic
Conductivity (m/yr)
254.8
254.8
254.8
254.8
Bulk Density
(g/cm3)
2.285
2.195
2.645
2.850
f
f
f
f
(1) Geometry
(5) Flow Characteristics
(A) Drain Properties
(3) Ditch Properties
i(2) Layer Properties!
Layer numbers increase from bottom to top.
Layers below each must be identical in all affected strips.
Layer Properties
>
Strip
Num
1
1
1
1
Strip Type
Paved Area
Paved Area
Paved Area
Paved Area
Layer
Num
1
2
3
A
Is Below
Drain
Layer Type
Subbast
Base
Base
Paveme
Thickness
(m)
.84
.14
.115
.125
Hydraulic
Cond (m/yr)
2548
254.8
254.8
254.8
Bulk Density
(g/cm3)
2.285
2.195
2.645
2.85
Figure C-7. Source Parameters (7) - Layer Properties.
This example has no ditches or drains, so the remaining tabs on Screen 7 (Ditch Properties, Drain
Properties, and Flow Characteristics) are not used.
C.2.2 Subsurface Parameters (Screen 8)
There are no site-specific subsurface data available; however, the predominating aquifer system
in the area is a glacial till overlaying sedimentary rock formations. Figure C-8 shows the
Subsurface Parameters screen populated based on this information. Because only the general
subsurface environment is known, the subsurface parameters are all sampled from distributions
specific to the selected subsurface environment in the Monte Carlo simulation.
C-5
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
I
Source Type (6)
Source Parameters (7)
[Subsurface Parameters (B)j
This screen allows you to enter or change the subsurface parameters.
You MUST select a Subsurface Environment. If you select'unknown'then the default values will be used for all parameters. In addition, you MAYenterva
parameter(s). Data sources are required.
Select the Subsurface Environment: |Till over Sedimentary Rock
Parameter
Ground-water pH value (metals only)
Depth to water table I
Regional hydraulic gradient
Aquifer thickness (m)
Default
I Distribution
I Distribution
I Distribution
I Distribution
I Distribution
Value
Data Source
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Figure C-8. Subsurface Parameters (8).
C.2.3 Infiltration Parameters (Screen 9)
The predominating regional surface soil material is sandy loam, and the rate of infiltration
through all the layers of the roadway is 0.0949 m/yr. The site is located in Lodi, WI, and the
closest climate center is Madison, WI. Figure C-9 shows the Infiltration screen populated based
on this information. The recharge rate is calculated for Madison, WI, and the predominant soil
type. This example has no ditch, so the Ditch Precip/Evap section is empty, as is the Runoff Rate
column under User-Specified Infiltration Rates.
Source Parameters (7)
Subsurface Parameters (8)
Infiltration (9) \ Constituent Li
r- Soil Data
Please select a soil to represent the
predom nate soil type surrounding
the roadway for soil parameters and
recharge determination:
Local C
Nearest
Selects
Strip #
1
imate Data
Climate Ce
deity
ecified Infiltr
Type
Paved
ter
vledium-grained soil (silt loam)
rine-grained soil (silty clay loam)
Unknown soil type
View Cities List
Madison
ation Rates (m/yr/
Infiltration
Rate
0.0949
WI
Source
User Entry
Default
Select
Runoff
Rate
All Scenarios
0.14
Precip and Evaporation in Ditches
Ditch Precipitation Evaporation
Strip Rate (m/yr) Rate (m/yr)
Figure C-9. Infiltration (9).
C.2.4 Constituent Parameters (Screens 10 and 11)
Recall from Table C-2 that only Layer 1 (the subbase) contains reused byproducts (foundry slag);
the other layers are asphalt or crushed aggregate. The foundry slag contains measurable amounts
of cadmium and selenium IV. Table C-3 shows the leachate and total (waste) concentrations for
these constituents.
C-6
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Table C-3. Constituent Concentrations for Layer 1 (Foundry Slag)
Constituent
Cadmium
Selenium IV
Leachate (mg/L)
0.0321
0.151
Waste (mg/kg)
0.0397
0.187
Figure C-10 shows the Constituent List screen populated based on this information. Note that
the columns for Layers 2 and 3 (and Layer 4, off the edge of the screen) are empty, as there are
no constituents present in those layers.
L
Ditches
1
Drains
(1) Paved Area
Constituent Initial Concentrations
>
Chemicals
CAS Number
7441H3-3
10026-03-G
Constituent Name
Cadmium
Selenium (IV)
Layer! -Subbase
Leachate
(mg/L)
0.0321
0.151
Total
(mg/kg)
0.0337
0.1 e?
Layer 2 - Base
Leachate (rng/L)
Total (mg/kg)
Layer 3 - Base
Leachate
(mg/L)
Total (mg/kg)
Figure C-10. Constituent List (10).
No site-specific information for constituent properties (Screen 1 1) is available, so the soil-water
partitioning coefficient (Kd) will be sampled from a distribution.
C.2.5 Reference Ground Water Concentrations (Screen 12)
Both cadmium and selenium IV have MCLs, which will be used for this example. Figure C-ll
shows the Reference GW Cone, screen populated based on this information.
Constituent List (10)
Constituent Properties (1 1)
J
Eefes r e n ce G WCp n cjjl 2)]
Select a constituent from the grid, then the desired standard from the list. Click the "Apply Standards" button to save each selection.
>
Related
Constituents
Constituent
7110-13-9 Cadmium
10026-03-6 Selenium (IV)
Standard
MCL
MCL
Standards for 7440-43-9 Cadmium
Reference Ground Water
Concentration (mg/L)
0.005
Exposure The exposure duration represents the
Duration (yr) time period a person is assumed to
ingest or inhale contaminated
groundwater corresponding to a
specific standard. Press F1 for more
information.
1
Select Standard
(• MCL
C H B N -1 n h al ati o n. Can ce r
(~ HBN-Inhalation, Non-Cancer
<~ HBN-Ingestion, Cancer
<~ HBN-Ingestion, Non-Cancer
(~ HBN-Dermal, Cancer
C HBN-Dermal, Non-Cancer
r Other Standard
<~ Compare to all available standards
Select the desired standard by clicking its radio button. Click the "Apply Standards" button to save your selection.
Reference
EditHBNs
Figure C-11. Reference Ground Water Concentration (12).
C-7
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IWEM User's Guide Appendix C: Example Problems for Roadway Evaluation
C.2.6 Results
As displayed on the Output Summary screen, IWEM determines that this roadway design with
industrial materials is appropriate—the estimated 90th percentile cconcentrations for cadmium
and selenium were below their respective MCLs. Empirical data collected at the site showed that
field observations were less than the results predicted by IWEM for both metals; however, the
predictions were correct with respect to the selected standards. By design, IWEM predictions
based on the substitution of national data for key site-specific data (subsurface parameters and
site-based partitioning coefficients) generate a conservative result; the result errs on the side of
environmental and human health protection. The IWEM reports from this example are provided
in Attachment C-l.
C.3 Example Problem 2 - Wisconsin State Highway 57, Waldo, Wl
A 1,829-m stretch of the northbound lane of WSH 57 between Waldo and Random Lake in
Sheboygan County, WI, was undergoing reconstruction in 2001. A nearby manufacturing
company, in Kohler, WI, generates spent foundry sands as part of its manufacturing process. In
an effort to utilize this industrial material for beneficial reuse, the company had the material
tested by a local engineering firm to see if it was structurally suitable for roadway fill. The firm
determined that the material could be used as fill material beneath lightly loaded structural
components (e.g., pavements) if kept at thicknesses between 0.6 and 1.2 m beneath the pavement
at density of 1.89 g/cm3. In addition, the firm subjected the material to the following analytical
tests: a total elemental analysis to determine what potentially hazardous constituents were present
in the material and at what total teachable concentrations; and a water leach test [ASTM D3987-
85 (WAC, 2006)] to estimate the potential leaching concentration of those constituents.
Although the results of the analytical tests did not identify any compounds at levels that exceeded
standards for the material or leachate concentrations established by the State of Wisconsin (WAC
Chapter NR 538), a modeling analysis was desired to confirm that the standards were in fact
protective of ground water according to the MCL for the constituents of concern: arsenic and
barium. The objective of this exercise is to confirm that the use of this foundry sand as a fill
material in the reconstruction of WSH 57 will be appropriate, based on the MCLs for arsenic in
and barium (0.01 and 2.0 mg/L, respectively).
We will demonstrate the use of the IWEM roadway module to perform a detailed analysis using a
combination of site-specific data and national data. This example is based upon data provided to
EPA by the Wisconsin DOT.
The following subsections describe the inputs for this example, along with screen captures
showing the populated screens.
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
C.3.1 Source Parameters (Screens 6 and 7)
Figure C-12 shows the facility identification information for this example.
Source Type (6)
Select Source Type —
r Landfill
T Waste Pile
I
Source Parameters (7)
I
Subsurface Parameter;
C Surface Impoundment
<"* Land Application Unit
<• i
Structural Fill
Facility Identification Information
Facility name
Street address
WSH 57 Foundry Sand Fill Analysis
WSH57
Waldo and Random Lake
Wl
Date of sample analysis
Name of user
Additional information
4/30/2007
EPA User
none
Figure C-12. Source Type (6).
Figure C-13 shows the layout of the well and road. The well is 61 m from the edge of the
roadway and located 6.1 m north of the middle of the roadway segment. Groundwater flow is
towards the southeast at an angle of 130° from the edge of the roadway.
Angle of flow with
respectto
roadway
Regional Flow Direction
Figure C-13. Roadway schematic for WSH 60.
C-9
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Appendix C: Example Problems for Roadway Evaluation
Figures C-14 and C-15 show Screen 7a and the well geometry portion of Screen 7 populated
based on the information provided above. The receptor well distance is provided from the edge
of the roadway, so needs no adjustment before entering in IWEM.
Location of Well with Respect to Roadway (7a)
We need to determine some basic relationships between the roadway, the direction oi
groundwater flow, and the location of the receptor well. Consider an orientation where the
direction oi groundwater flow is left to right.
The angle between the roadway and the groundwater flow is
The receptorwell is in [Region I * \
GW flow
Change Well Geometry
Shortest distance between the
roadway edge and the
monitoring well (m): [ei
Figure C-14. Location of Well with Respect to
Roadwav (7a) Distance along roadway from the point at which measurement
D was made to the midpoint of the roadway segment (point C in
the drawing) (m): r^j • (Linthe drawing)
Angle between roadway and groundwater flow (degrees): |130
Figure C-15. Source Parameters (7) - Well
Geometry.
Table C-4 provides the basic roadway geometry parameters, and Figure C-16 shows the
Geometry tab of the Source Parameters screen populated based on the provided data.
Table C-4. Roadway Geometry
Strip Type
Paved Area (PCC)
Width (m)
10.7
Layers
3
Length (m)
1,829
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Source Type (6)
Source Parameters (7)
I
Subsurface Parametei
This screen allows you to enter or change roadway parameters.
Number of roadway strips (include ditches in this count): J1
Number of drains (applicable only when a ditch is present): [o Roadway segment length (m): |1929
(5) Flow Characteristics
(A) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
Strip numbers increase with distance from well (1 is closest).
Roadway Geometry
>
Strip #
1
Strip Type
Paved Area
Width (m)
10.7
# of Layers
3
Figure C-16. Roadway Geometry (7).
Table C-5 provides the layer properties, and Figure C-17 shows the Layers tab of the Source
Parameters screen populated based on these data. When entering layer data, remember that layer
1 is the bottom layer.
Table C-5. Layer Material Properties
Layer
1 - Foundry Sand Fill
2 - Subbase material
3 - Portland Concrete
Thickness (m)
0.914
0.20
0.15
Hydraulic
Conductivity (m/yr)
1.74
1.74
1.74
Bulk Density
(g/cm3)
1.89
2.645
2.850
(1) Geometry
(5) Flow Characteristics
(A) Drain Properties
(3) Ditch Properties
i(2) Layer Properties!
Layer numbers increase from bottom to top.
Layers below each must be identical in all affected strips.
Layer Properties
I
Strip
Num
1
1
1
Strip Type
Paved Area
Paved Area
Paved Area
Layer
Num
1
2
3
Is Below
Drain
Layer Type
Fill
SubbasE
Pave me
Thickness
(m)
.914
.2
.15
Hydraulic
Cond (m/yr)
1.74
1.74
1.74
Bulk Density
(g/cm3)
1.89
2.645
2.85
Figure C-17. Source Parameters (7) - Layer Properties.
This example has no ditches or drains, so the remaining tabs on Screen 7 (Ditch Properties, Drain
Properties, and Flow Characteristics) are not used.
C-ll
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
C.3.2 Subsurface Parameters (Screen 8)
There are no site-specific subsurface data available; however, the predominating aquifer system
in the area is a glacial till overlaying sedimentary rock formations. Figure C-18 shows the
Subsurface Parameters screen populated based on this information. Because only the general
subsurface environment is known, the subsurface parameters are all sampled from distributions
specific to the selected subsurface environment in the Monte Carlo simulation.
Source Type (6)
Source Parameters (7)
Subsurface Parameters (8)
This screen allows you to enter or change the subsurface parameters.
I
You MUST select a Subsurface Environment. If you select'unknown1 then the default values will be used for all parameters. In addition, you MAY enter va
pararneter(s). Data sources are required.
Select the Subsurface Environment:
Till over Sedimentary Rock
Default
Ground-water pH value (metals (
Depth to water table (m)
Regional hydraulic gradient
I Distribution
I Distribution
I Distribution
I Distribution
I Distribution
Value
Data Source
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Figure C-18. Subsurface Parameters (8).
C.3.3 Infiltration Parameters (Screen 9)
The predominating regional surface soil material is silty or clayey loam, and the rate of
infiltration through all the layers of the roadway is unknown. The site is located in Waldo, WI,
and the closest climate center is Madison, WI. Figure C-19 shows the Infiltration screen
populated based on this information. Because there is no site-specific infiltration rate, a default is
used. By clicking on the |SELECT| button in the User-Specified Infiltration Rates table in the lower
left corner of Screen 9, the popup shown allows you to select the high or low range value for the
specified surface type (Portland concrete cement). The recharge rate is calculated for Madison,
WI, and the predominant soil type. This example has no ditch, so the Ditch Precip/Evap section
is empty (and hidden under the infiltration popup in Figure C-19), as is the Runoff Rate column
under User-Specified Infiltration Rates.
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Appendix C: Example Problems for Roadway Evaluation
Source Parameters (7)
Subsurface Parameters (8]
Constituent List (10)
Soil Data
Please select a soil to represent the
predominate soil type surrounding the
roadway for soil parameters and
recharge determination:
Coarse-grained soil (sandy loam)
Medium-grained soil (silt loam)
Unknown soil type
Local Climate Data
Nearest Climate Center
Selected city Madison Wl
View Cities List
User Specified Infiltration Rates (m/yr/unit area)
Strip #
1
Type
Paved
Infiltration
Rate
0.3531
Source
Portland Cement
Default
Select
Runoff
Raje^
^^
^->
±\
Click "Select" in the desired row to select from pre-defined infiltration rates, or enter the desired value in ti
rfiltrniion rate column.
Recharge Rate (m/yr)
All Scenarios
Roadway Strip Infiltration
Selectthe infiltration characteristics for Strip 1 (Paved Area)
Surface type: Portland Cement Concrete (PCC)
F Select high range value (.3531 m/yr)
[~~ Select low range value (.00003454 m/yr)
OK
Cancel
Figure C-19. Infiltration (9).
C.3.4 Constituent Parameters (Screens 10 and 11)
Recall from Table C-5 that only Layer 1 (the fill layer) contains reused byproducts (foundry
sand); the other layers are subbase or Portland cement concrete. The foundry sand contains
arsenic HI and barium. Table C-6 shows the leachate and total (waste) concentrations for these
constituents.
Table C-6. Constituent Concentrations for Layer 1 (Foundry Sand)
Constituent
Arsenic III
Barium
Leachate (mg/L)
0.05
0.27
Waste (mg/kg)
10.6
8.0
Figure C-20 shows the Constituent List screen populated based on this information. Note that
the columns for Layers 2 and 3 are empty, as there are no constituents present in those layers.
[Strips!
L
Ditches
Drains
(1) Paved Area
Constituent Initial Concentrations
>
Chemicals
CAS Number
22669-72-6
7410-39-3
Constituent Name
Arsenic (III)
Barium
Layer 1 - Fill
Leachate
(mg/L)
0.05
0.27
Total
(mg/kg)
10.6
8
Layer 2 -Subbase
Leachate (mg/L)
Total (mg/kg)
Layer 3 - Pavement
Leachate
(mg/L)
Total (mg/kg)
Figure C-20. Constituent List (10).
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IWEM User's Guide Appendix C: Example Problems for Roadway Evaluation
No site-specific information for constituent properties (Screen 11) is available, so the soil-water
partitioning coefficient (Kd) will be sampled from a distribution.
C.3.5 Reference Ground Water Concentrations (Screen 12)
Both arsenic and barium have MCLs, which will be used for this example. Figure C-21 shows
the Reference GW Cone, screen populated based on this information.
Constituent List (10)
Constituent Properties 11) j Reference GW Cone. (12)1 j Input Summary (1 3)
Select a constituent from the grid, then the desired standard from the list. Click the "Apply Standards" button to save each selection.
>
Related
Constituents
Standards f
Select Standar
« MCL
C HBN -Inhale
r HBN -Inhale
r HBN-lnges
C HBN-lnges
r HBN -Derm
r HBN -Derm
C Other Stand
C Compare to
Select the desi
Constituent
22569-72-8 Arsenic (III)
7440-39-3 Barium
Standard
MCL
MCL
or 22569-72 8 Arsenic (III)
Reference Ground Water Exposure The exposure duration represents the
j Concentration (rng/L) Duration (yr) time period a person is assumed to
lion. Cancer
lion, Non-Cancer
on. Cancer
on, Non-Cancer
3l, Cancer
al, Non-Cancer
ard
all available standards
ed standard by clicking its radio
0.01
button. Click the "Apply S
information
EditHBNs
r
andards" button to save your selection.
Figure C-21. Reference Ground Water Concentration (12).
C.3.6 Results
As displayed on the Output Summary screen, IWEM predicts that the roadway design exceeds the
benchmark for arsenic in —the 90th percentile concentration for arsenic HI is above its MCL.
However, the 90th percentile concentration for barium was below the selected benchmark. The
IWEM reports from this example are provided in Attachment C-l.
C.4 Example Problem 3 - Minnesota Road Research Facility
(MNROAD), Low Volume Road, Monticello, MN
The MnROAD facility1 is operated by the Minnesota Department of Transportation (Mn/DOT),
and is located in east-central Minnesota adjacent to Interstate 94 between Albertville and
Monticello, MN, northwest of the Minneapolis/St. Paul metropolitan area. MnROAD is a cold-
region testing laboratory with three instrumented test roadways used to track pavement
performance over time. The 2.5-mile low-volume roadway, used to simulate conditions on rural
roads, has several segments used for various experiments. One test segment uses high carbon fly
ash (HCFA) to stabilize the base course beneath hot mix asphalt. This segment, along with
control segments, has been instrumented with lysimeters to capture leachate from the stabilized
base materials to evaluate the environmental performance of HCFA-stabilized bases. Most
information used in this example comes from a Mn/DOT report (Wen, 2008), a construction
drawing provided by Mn/DOT, and a master's thesis (O'Donnell, 2009), submitted to the
University of Wisconsin, which is a partner in the research project.
http://www.dot.state.mn.us/mnroad/
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Appendix C: Example Problems for Roadway Evaluation
The HCFA is produced by the combustion of coal at an electric power plant in North
Minneapolis. Data from an elemental analysis of the HCFA, as well as data collected from the
lysimeters, will be used to characterize the mix of recycled pavement materials (RPM) and
HCFA used for the base course. The resulting material is referred to as RPM with fly ash, or
RPM/FA.
The objective of this example is to determine if some of the constituents found in the leachate at
levels higher than Minnesota Pollution Control Agency (MPCA) MCLs—arsenic (10 ug/L) and
cadmium (4 ug/L)—would pose a risk to hypothetical receptors at distances of 10 and 150 m
away from the edge of the highway test section, measured from the center of the roadway. This
will necessitate two separate runs for IWEM, one for each receptor distance. The following
subsections describe the inputs for this example, along with screen captures showing the
populated screens.
C.4.1 Source Parameters (Screens 6 and 7)
Figure C-22 shows the facility identification information for this example.
Source Type (6)
Select Source Type —
r Landfill
C Waste Pile
I
Source Parameters (7)
Subsurface Parameter;
f" S_urface Impoundment
(~ Land Application Unit
(• BO ad way
r Structural Fill
Facility Identification Information
MnRoad Test Section 79
Street add res
Low Volume Roadway
Monticello
MN
Date of sample analys
Name of user
Additional information
May 2010
EPA user
none
Figure C-22. Source Type (6).
The roadway dimensions and layer profiling were given in Wen (2008). Figure C-23 shows the
layout. The hypothetical wells are 10m and 150 m from the edge of the roadway and located at
approximately the middle of the length of the roadway segment. Groundwater flow is
perpendicular to the roadway and flows in the direction of the well. This orientation implies that
the angle between the roadway and the groundwater flow direction is 90°.
Figures C-24 and C-25 show Screen 7a and the well geometry portion of Screen 7 populated
based on the information provided above (note, Figure C-25 shows Screen 7 populated for the
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Appendix C: Example Problems for Roadway Evaluation
10-m well distance; for the 150-m well distance, the first field in Figure C-25 would be 150
instead of 10; the two analyses are otherwise identical). Because the well is located along the line
that bisects the roadway (the green line in Figure C-4), either Region selection (Region I or
Region n) on Screen 7a will work. The receptor well distance is provided from the edge of the
roadway, so needs no adjustment before entering in IWEM. The well is described as located at
"approximately the middle of the roadway segment," so the distance along the roadway from the
midpoint (Figure C-25) is set to zero.
Figure C-23. Roadway schematic for WSH 60.
.ocation of Well with Respect to Roadway (7a)
We need to determine some basic relati-nnship^ bgVeen the roadway 'he direction of
groundwaterflow, and the location of the receptor well. Consider an orientation where the
direction of cjroundwaterflowis left to right.
The angle between the madwav and the grouridwatei
The receptorwel] is in |Region I -r |
GW flow
Change Well Geometry
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Appendix C: Example Problems for Roadway Evaluation
Figure C-24. Location of Well with Respect to
Roadway (7a).
Figure C-25. Source Parameters (7) -Well
Geometry.
Table C-7 provides the basic roadway geometry parameters, and Figure C-26 shows the
Geometry tab of the Source Parameters screen populated based on the provided data.
Table C-7. Roadway Geometry
Strip Type
Paved Area
Width (m)
8.5
Layers
2
Length (m)
115
The dry unit weight of the stabilized material was reported as 19.6 kN/m3, which converts to a
bulk density of 1.99 g/cm3. The bulk density of the hot mix asphalt pavement is assumed to be
2.31g/cm3.
Source Type (6)
J
Source Parameters (7)
L
Subsurface Parametf
This screen allows you to enter or change roadway parameters.
Number of roadway strips (include ditches in this count): |1
Number of drains (applicable only when a ditch is present): lo Roadway segment length (m): |115
I
(5) Flow Characteristics
(4) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
strip numbers increase with distance from well (1 is closest).
Roadway Geometry
>
Strip*
1
Strip Type
Paved Area
Width (m)
8.5
# of Layers
2
Figure C-26. Roadway Geometry (7).
Table 6-17. Material Properties Used in the HELP Model
Material hydraulic conductivity values were not
provided in either report, so values
corresponding to low-end, flexible pavements
for the base and top course materials were
assumed as the test section was newly paved
and not fractured. (See IWEM Technical
Background Document Table 6-17; screen
capture of the relevant portion at right with the
values used circled; these were converted to m/yr by multiplying by the conversion factor
315,576 [m/yr]/[cm/sec])
Flexible Paveir
Low-end*
High-endf
Layer
ent (asphal
L-1
L-2
L-3
H-1
H-2
H-3
Description
ic concrete pavemf
Top course
Base course
Subbase course
Top course
Base course
Subbase course
Hydraulic
Conductivity
(cm/sec)
nt)^ ^
7 1.00E-05 "\
V^SOE-OjjX
4.30E-05
48'
35
35
Air void
(%)
29
50
50
24
39
39
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Appendix C: Example Problems for Roadway Evaluation
Table C-8 provides the layer properties, and Figure C-27 shows the Layers tab of the Source
Parameters screen populated based on these data. When entering layer data, remember that layer
1 is the bottom layer.
Table C-8. Layer Material Properties
Layer
1 - RPM/FA base course
2 - Hot Mix Asphalt
Thickness (m)
0.203
0.102
Hydraulic
Conductivity (m/yr)
13.6
3.2
Bulk Density
(g/cm3)
1.99
2.31
f
(1) Geometry
(5) Flow Characteristics
[ (A) Drain Properties
J_
(3) Ditch Properties
i(2) Layer Properties!
Layer numbers increase from bottom to top.
Layers below each must be identical in all affected strips.
Layer Properties
Strip
Num
> 1
1
Strip Type
Paved Area
Paved Are a
Layer Is BE
Num Drai
1
2
low Layer Type
i
Base
Pave me
Thickness
(m)
.203
.102
Hydraulic Bulk Density
Cond (m/yr) (g/cm3)
13.6 1.99
3.2 2.31
Figure C-27. Source Parameters (7) - Layer Properties.
This example has no ditches or drains, so the remaining tabs on Screen 7 (Ditch Properties, Drain
Properties, and Flow Characteristics) are not used.
C.4.2 Subsurface Parameters (Screen 8)
Research into the regional hydrologic setting indicated that the surficial aquifer is comprised
mostly of unconsolidated glacial till on top of sedimentary rocks. No site-specific data regarding
the pH, hydraulic conductivity, hydraulic gradient, or thickness of the surficial aquifer were
available; however, a nearby monitoring well measures the depth to the water table at 1.35 m.
Figure C-28 shows the Subsurface Parameters screen populated based on this information.
Depth to water table has been filled in with the known value, and the rest of the subsurface
parameters, for which data are not available, are sampled from distributions specific to the
selected subsurface environment in the Monte Carlo simulation.
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Appendix C: Example Problems for Roadway Evaluation
Source Type (6)
Source Parameters (7)
Subsurface Parameters (8)
"his screen allows you to enter or change the subsurface parameters.
'ou MUST select a Subsurface Environment. If you select'unknown1 then the default values will be used for all parameters. In addition, you MAY enter values'
larameter(s). Data sources are required.
Select the Subsurface Environment:
Parameter
Ground-water pH value (metals only)
Depthtowatertable(m)
Aquifer hydraulic conductivity (m/yr)
Regional hydraulic gradient
Default
I Distribution
I Distribution
I Distribution
I Distribution
Value
1.35
Data Source
Monte Carlo [see Note 1]
Monitoring well data near Section 79
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Figure C-8. Subsurface Parameters (8).
C.4.3 Infiltration Parameters (Screen 9)
The surflcial soils are of a silty, clayey nature. Lysimeter data indicated a long-term average
water flux of 0.5 mm/day or 0.1825 m/yr. The site is located in Monticello, MN, and the closest
climate center is St. Cloud, MN. Figure C-29 shows the Infiltration screen populated based on
this information. The recharge rate is calculated for St. Cloud, MN, and the predominant soil
type. This example has no ditch, so the Ditch Precip/Evap section is empty, as is the Runoff Rate
column under User-Specified Infiltration Rates.
Source Parameters (7)
Subsurface Parameters (
Infiltration (9);
L
Constituent List (10)
Soil Data -^^^^^^^^^^^^^^
Please select a soil to represent the I Coarse-grained soil (sandy loam)
predominate soil type surrounding the Medium-grained soil (silt loam)
roadway for soil parameters and
recharge determination: Unknown soil type
Local Climate Data
Nearest Climate Center
Selected city St. Cloud MN
View Cities Li si
User Specified Infiltration Rates (m/yr/unitarea)
Strip*
1
Type
Paved
Infiltration
Rate
0.1825
Source
User Entry
Default
Select
Runoff
Rate
Click "Select" in the desired row to select trom pre-detineci mliltration rates, or enter the desired value in the Rates are m/yr/unitarea
infiltration rate column.
Recharge Rate (m/yr)
All Scenarios
Ditch Precip/Evap
Precip and Evaporation in Ditches
Ditch Precipitation Evaporation
Strip Rate (rn/yr) Rate (m/yr)
Figure C-29. Infiltration (9).
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Appendix C: Example Problems for Roadway Evaluation
C.4.4 Constituent Parameters (Screens 10 and 11)
Recall from Table C-8 that only Layer 1 (the stabilized base course) contains reused byproducts
(HCFA); the other layer is asphalt. The leachate concentrations for the stabilized base course are
based on the lysimeter data, using the average leachate concentrations for arsenic in and
cadmium. For waste concentrations, analytical analysis yielded concentrations in the HCFA of
24 mg/kg for arsenic HI and 5.4 mg/kg of cadmium. The RPM/FA that makes up the stabilized
base is 14% HCFA by weight (the remaining 86% is assumed to contain no teachable
constituents). Therefore, a mass-weighted average of the HCFA and the remaining portion of the
RPM/FA yields overall concentrations of 3.4 mg/kg of arsenic HI (24 mg/kg x 0.14) and
0.76 mg/kg of cadmium (5.4 mg/kg x 0.14) in the RPM/FA. Conservatively, we will assume
these values represent the total teachable waste concentrations. Table C-9 summarizes these
leachate and total (waste) concentrations.
Table C-9. Constituent Concentrations for Layer 1 (Stabilized Base Course)
Constituent
Arsenic III
Cadmium
Leachate (mg/L)
0.0692
0.00523
Waste (mg/kg)
3.4
0.76
Figure C-30 shows the Constituent List screen populated based on this information. Note that
the columns for Layer 2are empty, as there are no constituents present in that layer.
;S trips;
(1) Paved Area
| Ditches | Drains
1
Constituent Initial Concentrations
>
Chemicals
CAS Number
22569-72-3
7440-43-9
Constituent Name
Arsenic (III)
Cadmium
Layer! -Base
Leachate
(mg/L)
0.0692
0.0052
Total
(mg/kg)
3.4
0.76
Layer 2 - Pavement
Leachate (mg/L)
Total (mg/kg)
Figure C-30. Constituent List (10).
No site-specific information for constituent properties (Screen 11) is available, so the soil-water
partitioning coefficient (Kd) will be sampled from a distribution.
C.4.5 Reference Ground Water Concentrations (Screen 12)
For this example, we will use the Minnesota Pollution Control Agency (MPCA) MCLs for
arsenic m and cadmium. For arsenic HI, this is 0.01 mg/L, which is the same as the national
MCL provided in IWEM. For cadmium, this is 0.004 mg/, slightly lower than the national MCL
of 0.005 mg/L. Thus, the provided MCL can be used for arsenic HI, but the MPCA MCL for
cadmium must be entered as an "Other Standard." Figure C-31 shows the Reference GW Cone.
screen populated based on this information.
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Appendix C: Example Problems for Roadway Evaluation
Constituent List (1 0)
Constituent Properties (11)
Reference GW Cone. (12)!
Select a constituentfrom the grid.thenthe desired standard from the list. Click the 'Apply Standards" button to save each selection.
t
Related
Constituents
Constituent
22569-72-3 Arsenic (III)
7440-43-9 Cadmium
Standard
MCL
User Defined
Standards for 7440-43-9 Cadmium
Reference Ground Water
Concentration (mg/L)
Select Standard
Exposure
Duration (yr)
r
r
r
r
r
r
0.005
MCL
HBN - Inhalation, Cancer
HBN - Inhalation, Non-Cancer
HBN - Ingestion, Cancer
HBN - Ingestion, Non-Cancer
HBN-Dermal, Cancer
C HBN - Dermal, Non-Cancer
(• Other Standard
<~ Compare to all available standards
Select the desired standard by clicking its radio button. Click the "Apply Standards" button to save your selection.
0.004
The exposure duration represents the
time period a person is assumed to
ingest or inhale contaminated
groundwater corresponding to a
specific standard. Press F1 for more
information.
Reference
EditHBNs
MPCA MCL
Figure C-31. Reference Ground Water Concentration (12).
C.4.6 Results
As displayed on the Output Summary screen, IWEM predicts that the roadway design exceeds the
benchmarks for both arsenic in and cadmium at the well 10m from the roadway. The 90th
percentile concentration for arsenic HI is 0.0524 mg/L (compared to an MCL of 0.01 mg/L). The
90th percentile concentration for cadmium is 0.0048 mg/L (compared to an MCL of
0.004 mg/L). Given that the initial leachate concentrations are 0.0692 mg/L for arsenic and
0.0052 mg/L for cadmium, the well concentrations are 76% and 92% of the initial concentrations
for arsenic and cadmium, respectively. Therefore, clearly little dilution of the leachate occurs
between the roadway and the 10-m receptor location.
In contrast, the 150-m well location provides sufficient dilution and attenuation to reduce the
magnitude of the 90th percentile arsenic HI and cadmium concentrations to 0.009 mg/L and
0.0009 mg/L, which are both below the MCLs (although, in the case of arsenic IE, just barely
below). The IWEM reports from this example are provided in Attachment C-l.
C.5 Example Problem 4 - Minnesota Road Research Facility
(MNROAD), Low Volume Road, Monticello, MN
This example is a hypothetical problem to demonstrate how the Roadway module in IWEM
could be used to approximate multiple sections of a road potentially impacting a single receptor.
As mentioned in Section C.2.2.6 of the IWEM Technical Background Document (U.S. EPA,
2014), the approach presented here is only an approximation of the aggregate effects on a single
receptor. The Agency highly recommends that a detailed, site-specific analysis be conducted for
such a complex scenario, with the assistance of qualified and experienced personnel.
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Appendix C: Example Problems for Roadway Evaluation
This example is an extension of the previous MnROAD facility example (Example 3) and uses
the same roadway section three times with different segment lengths and well location.
The following subsections describe the inputs for this example, along with screen captures
showing the populated screens for those that are different from Example 3.
C.5.1 Source Parameters (Screens 6 and 7)
This is the same as Figure C-22 except that the Segment (A, B, or C) is added to the Additional
Information field.
Figure C-32 depicts a hypothetical bend in
the road around the well and shows the
ground water flow angles (in yellow),
distances to the well (D; in turquoise), and
distances from the midpoint of the segment
(L, in fuschia). Ground water flow is
perpendicular to segment B. Given the ground
water flow direction and the receptor location,
only the bend of the roadway is likely to have
any water quality impacts at the well. Each of
the idealized roadway segments, A, B, and C,
is 100 m long, and the angles between
segments A & B and B & C are 135°. The
idealized problem geometry allows us to
derive all of the necessary IWEM receptor
location inputs. The objective of this example
is to determine if aggregated ground water
concentrations of arsenic or cadmium would
exceed the MPCA MCLs at the hypothetical
well located 75 m away from segment B,
measured from the center of the roadway.
This will necessitate three separate runs for
IWEM, changing only the receptor location
parameters for each simulation.
Idealized roadway
• Well
GW flow direction
Figure C-32. Roadway schematic for WSH 60.
Table C-10 provides the basic roadway geometry parameters based on the information provided
above.
Table C-10. Roadway Geometry
Segment
A
B
C
Type
Paved
Area
Width (m)
8.5
Layers
2
Length
(m)
100
Angle
45°
90°
135°
DistanceD
(m)
85.4
70.7
85.4
Distance!.
(m)
35.4
0.0
35.4
Figures C-33 and C-34 show Screen 7a and the well geometry portion of Screen 7 populated
based on the information provided above. The receptor well distance D in IWEM (Figure C-35)
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Appendix C: Example Problems for Roadway Evaluation
is measured from the edge of the roadway; however, the information provided is from the
centerline of roadway Segment B. Thus, you need to subtract half the roadway width (8.5 m/2 =
4.3 m) from the given well distance from the centerline of Segment B (75 m - 4.3 m = 70.7 m) to
get the distance from the edge of Segment B. The other distances can be derived using the
idealized geometry.
Location of Well with Respect to Roadway (7a)
We need to determine some bssic relationships between the roadway, the direction of
groundwaterflow, Qndthe location of the receptor well. Consider an orientation where the
direction of groundwaterflow is left to right
GW flow
I
Well
Segment A
The angle between the roadway and the groundwaterfiowis
The receptorwel! is in [Region II
Segment B
The angle between the roadway and the qroundwsterflowis
The receptorwell is in [Region II
Segment C
The angle between the roadway and the groundwaterfiowis
The receptorwell is in JRegion I
Figure C-33. Location of Well with Respect to
Roadway (la).
GW flow
Segment A
Well
Change Well (jeometry
Shortest distance between the
roadway edge and the
monitoring well (m): [35!
Distance along roadway from the point at which measurement
D was made to the midpoint of the roadway segment (point C in
the drawing) (m): |3g^ ' (Linthe drawing)
Angle between roadway and groundwaterflow (degrees): p5
Shortest distance between the
roadway edge and the Segment B
monitoring well (m): 170.7
Distance along roadway from the point alwhich measurement
D was made to the midpoint of the roadway segment (point C in
the drawing) (m): |jj ' (Linthe drawing)
Angle between roadway and groundwaterflow (degrees): J90
Shortest distance between the
roadway edge and the Segment C
monitoring well (m): 135.4
Distance along roadway from the point atwhich measurement
D was made to the midpoint of the roadway segment (point C in
the drawing) (m): j^j ' (Linthe drawing)
Angle between roadway and groundwaterflow (degrees): |135
Figure C-34. Source Parameters (7) - Well
Geometry.
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Appendix C: Example Problems for Roadway Evaluation
Figure C-35 shows the Geometry tab of the Source Parameters screen populated based on the
provided data.
Source Type (G)
J
iSource Pararneters (7)i
I
Subsurface Paramete
This screen allows you to enter or change roadway parameters.
Number of roadway strips (include ditches in this count): |1
Number of drains (applicable only when a ditch is present): [o Roadway segment length (m): |100
(5) Flow Characteristics
(4) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
Strip numbers increase with distance from well (1 is closest).
Roadway Geometry
>
Strip #
1
Strip Type
Paved Area
Width (m)
8.5
# of Layers
2
Figure C-35. Roadway Geometry (7).
All remaining parameters and screens are as shown for Example 3 (Section C.4).
C.5.2 Results
Results of the three simulations are presented in The aggregated concentration for arsenic HI
exceeds the MCL, while the concentration for cadmium does not.
Table . The 90th percentile concentrations are summed for each constituent to approximate the
aggregate effect of three modeled segments at the receptor well. As expected, the effect of
Segment B dominates the result. The aggregated concentration for arsenic m exceeds the MCL,
while the concentration for cadmium does not.
Table C-13. Example 4 Aggregate Results
Constituent
Arsenic III
Cadmium
90th Percentile Concentration Results by
Segment (mg/L)
Segment A
2.0E-08
1.9E-09
Segment B
0.016
0.0017
Segment C
2.0E-08
1.9E-09
Aggregate 90th
Percentile
Concentration
(mg/L)
0.016
0.0017
MPCA
MCL
(mg/L)
0.01
0.004
Below/Exceeds
Benchmark?
Exceeds
Below
The IWEM reports from this example are provided in Attachment C-l.
C.6 Example Problem 5 - Hypothetical Roadway
This example is a hypothetical problem to demonstrate all of the features of the Roadway module
in IWEM including ditches, drains, and gutters. This example originates as part of a verification
problem in Appendix C of the IWEM Technical Background Document and many values are
taken from tables presented in Section 6 of that document. Figure C-36 depicts the hypothetical
C-24
-------
IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
roadway cross-section of nine strips and as many as three non-drainage layers. Other features
included are two ditches, two drains, two gutters, and surface runoff. The objective of this
example is to familiarize you with the various options available for simulating a more complex
roadway scenario.
Gutter Traveled Lanes
Strip #^
Collected Leachate
Ditch
Collected Leachate
Figure C-36. Cross Section of a Roadway Segment in Verification Case 4 with Two Symmetric
Drainage Systems [not to scale]
The following subsections describe the inputs for this example, along with screen captures
showing the populated screens.
C.6.1 Source Parameters (Screens 6 and 7)
Figure C-37 shows the facility identification information for this example.
I
I
Source Type (6)
Select Source Type —
r Landfill
C Waste Pile
Source Parameters (7)
Subsurface Paramete
C Surface Impoundment
C Land Application Unit
** Bp.adwa'yi
C Structural Fill
Facility Identification Information
Appendix C Example 5 - Verification Problem
Street address
Date of sample analysis
Figure C-37. Source Type (6).
Figure C-38 shows the layout of the well and road. The well is 30.5 m down gradient from the
roadway edge, and located at the midpoint of the roadway segment. Groundwater flow is
perpendicular to the roadway.
C-25
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Angle of flow
with respect to
roadway
Groundwater Flow
Direction
Figure C-38. Roadway schematic for WSH 60.
Figures C-39 and C-40 show Screen 7 a and the well geometry portion of Screen 7 populated
based on the information provided above. The receptor well distance is provided from the edge
of the roadway, so needs no adjustment before entering in IWEM. The well is assumed to be
located at approximately the middle of the roadway segment, so the distance along the roadway
from the midpoint (Figure C-40) is set to zero.
Location of Wei! with Respect to Roadway (7a)
We need to determine some basic relationships between the roadway, the direction of
groundwater flow, and the location of the receptor well. Consider an orientation where the
direction of groundwater flow is left to right
The angle between the roadway .and the cruundwaterflowis
The receptorwell is in [Region I
GW flow
Change Well Geometry
Figure C-39. Location of Well with Respect to
Roadway (la).
Shortest distance between the
roadway edge and the
monitoring well (m): hg.5
Distance along roadway from the point at which measurement
D was made to the midpoint of the roadway segment (point C in
the drawing) (m): rj— ' (L in the drawing)
Angle between roadway and groundwater flow (degrees): NO
Figure C-40. Source Parameters (7) - Well
Geometry.
C-26
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Table C-14 provides the basic roadway geometry parameters, Table C-15 contains information
to populate the Drain Geometry tables also on the Geometry tab, and Figure C-41 shows the
Geometry tab of the Source Parameters screen populated based on the provided data.
Table C-14. Roadway Geometry
Table C-15. Drain Configuration
Strip
Number
1
2
3
4
5
6
7
8
9
Type
Ditch
Embankment
Pavement
Pavement
Median
Pavement
Pavement
Embankment
Ditch
Width
(m)
3
3
3
3
3
3
3
3
3
Layers
1
2
3
3
2
3
3
2
1
Drain
Number
1
2
Strips
Strip Numbers
Captured by
Drain
3,4
6, 7
Configuration
Drains to
Ditch in Strip
Number
1
9
Drain is
Above
Layer
1
1
Source Type (6)
I
I Source Parameters (7)j
I
Subsurface Paramete
This screen allows you to enter or change roadway parameters.
Number of roadway strips (include ditches in this count): |9
Number of drains (applicable only when a ditch is present): [2 Roadway segment length (m): |120
(5) Flow Characteristics
(A) Drain Properties
(3) Ditch Properties
(2) Layer Properties
(1) Geometry
Strip numbers increase with distance from well (1 is closest).
Roadway Geometry
>
Strip*
1
2
3
A
5
6
7
8
9
Strip Type
Ditch
Embankment
Paved Area
Paved Ares.
Median
Paved Area
Paved Area
Embankment
Ditch
Width (m)
3
3
3
3
3
3
3
3
3
# of Layers
1
2
3
3
2
3
3
2
1
Layer numbers increase from bottom to top.
Drain Geometry -Strips
»•
*
Drain ID
Drain 1
Drain 1
Drain 2
Drain 2
Drains strip
3
A
6
7
Drain Geometry -Configuration
t
Drain ID
Drain 1
Drain 2
Drains to
Ditch in Strip
1
3
-r
Drain is
above layer
1
1
Figure C-41. Roadway Geometry (7).
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Table C-16 provides the layer properties, and Figure C-42 shows the Layers tab of the Source
Parameters screen populated based on these data. When entering layer data, remember that layer
1 is the bottom layer. Asphaltic concrete is used for the paved surface, and other surfaces are
unpaved. The low-end values for hydraulic conductivity are taken from Table 6-17 in the IWEM
Technical Background Document. Bulk density is assumed to be constant for all materials.
Table C-16. Layer Material Properties
Strip Number(s)
1, 9 -Ditch
2, 8 - Embankment
3, 4,6,7 - Pavement
5 - Median
Layer
1 -Fill
1 -Fill
2 -Fill
1 - Subgrade
2 - Base
3 - Pavement
1 -Fill
2 -Fill
Thickness
(m)
0.45
0.6
0.75
0.6
0.3
0.3
0.6
0.75
Hydraulic
Conductivity
(m/yr)
13.6a
13.6a
13.6a
13.6b
13.6b
3.16C
13.6d
13.6d
Bulk
Density
(g/cm3)
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Contains Reused
Material with
Arsenic III
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
a Low-end embankment base course; 4.3E-05 cm/sec
b Low-end flexible pavement (asphaltic concrete pavement) base/subbase course; 4.3E-05 cm/sec
c Low-end flexible pavement (asphaltic concrete pavement) top course; 1E-05 cm/sec
d Low-end unpaved median base/subbase course; 4.3E-05 cm/sec
(1) Geometry
[ (5)FlowCharacteristics
(A) Drain Properties
( (3) Ditch Properties
[(2) Layer Properties!
Layer numbers increase from bottom to top.
Layers below each must be identical in all affected strips.
Layer Properties
>
Strip
Num
1
2
2
3
3
3
A
4
4
5
5
6
6
6
7
7
7
8
8
9
Strip Type
Ditch
Embankment
Embankment
Paved Area
Paved Area
Paved Area
Paved Area
Paved Area
Paved Area
Median
Median
Paved Area
Paved Area
Paved Area
Paved Area
Paved Area
Paved Area
Embankment
Emba.nkment
Ditch
Layer
Num
1
1
2
1
2
3
1
2
3
1
2
1
2
3
1
2
3
1
2
1
Is Below
Drain
1
1
2
2
Layer Type
Fill
Fill
Fill
Subgrad
Base
Pave me
Subgrad
Base
Pave me
Fill
Fill
Subgrad
Base
Pave me
Subgrad
Base
Pave me
Fill
Fill
Fill
Thickness
(m)
.45
.6
.75
.6
.3
.3
.6
.3
.3
.6
.75
.6
.3
.3
.6
.3
.3
.6
.75
.45
Hydraulic
Cond (m/yr)
13.6
13.6
13.6
13.6
13.6
3.6
13.6
13.6
3.6
13.6
13.6
13.6
13.6
3.16
13.6
13.6
3.16
13.6
13.6
13.6
Bulk Density
(g/cm3)
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
-
Figure C-42. Source Parameters (7) - Layer Properties.
C-28
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Table C-17 contains information to populate the Ditch Properties table and Figure C-43 shows
the Ditch tab of the Source Parameters screen populated based on these data. The values for
Manning's n correspond to a clean, straight newly excavated channel and are taken from
Table 6-4 in the IWEM Technical Background Document. The slope value is very small
indicating that the roadway is relatively flat.
Table C-17. Ditch Properties Configuration
Ditch Strip
Number
1
9
Manning's n
0.016
0.016
Slope (m/m)
1E-08
1E-08
Max Depth
(m)
1
1
Gutter is Between
Strip Number
2
7
Strip Number
3
8
(2) Layer Properties
(1) Geometry
(5) Flow Characteristics
) Drain Properties
i(3) Ditch Properties;
Ditch Properties
>
Strip
1
9
Manning's
n
.016
.016
Slope
(m/m)
1E-08
IE-OB
Max
depth (m)
1
1
Gutter
F
F
Between
strip
2
7
and
strip
3
8
Figure C-43. Source Parameters (7) - Ditch Properties Tab.
Table C-18 contains information to populate the Drain Properties table, and Figure C-44 shows
the Drain tab of the Source Parameters screen populated based on these data. The value of
hydraulic conductivity is assumed to be very high so that there is very little resistance to flow and
water can move through the drain very easily and quickly.
Table C-18. Drain Properties
Drain Number
1
2
Thickness (m)
0.15
0.15
Hydraulic
Conductivity (m/yr)
1.095E+07
1.095E+07
Bulk Density
(g/cm3)
2.0
2.0
C-29
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
(3) Ditch Properties
(2) Layer Pro parties
(1) Geometry
(5) Flow Characteristics
1(4) Drain Properties
j
Drain Properties
>
ID
Drain 1
Drain 2
Thickness
(m)
.15
.15
Hydraulic
Conductivity (m/yr)
1.095E+07
1.095E+07
Bulk Density
(g/cm~3)
2
2
Figure C-44. Source Parameters (7) - Drain Properties Tab.
Table C-19 contains information to populate the Flow Characteristics table, and Figure C-45
shows the Flow tab of the Source Parameters screen populated based on these data. These values
define how much runoff reaches a ditch and how much vertical flow through the strips underlain
by drains is diverted to ditches. Runoff that does not reach a ditch is diverted by the gutter. The
values were chosen arbitrarily. Finally, the arrows above the roadway in Figure C-36 indicate the
direction and contributions of runoff from the roadway.
Table C-19. Flow Characteristics
Item
Ditch Strip 1
Ditch Strip 9
Drain 1
Drain 2
Ditch Strip 1
Ditch Strip 9
Information
Percent of
runoff that
reaches this
ditch
Percent of flow
through this
drain that
reaches the
ditch
Strips providing
runoff to ditch
Value (%)
50
50
50
50
2, 3, 4, 5
6, 7, 8
C-30
-------
IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
(A) Drain Properties
\ (3) Ditch Properties
(2) Layer Properties
| (1) Geometry
i(5) Flow Characteristics!
Flow Percentages to Ditch Strips
>
Item Information
Strip! Pe rce nt of ro ad way ru n off th at reaches
ditch beyond gutter
Strip9 Pe rce nt of ro ad way ru n off th at reaches
ditch beyond gutter
Drain 1 Percent of flow in Drain 1 that reaches
ditch
Drain 2 Percent of flow in Drain 2 that reaches
ditch
Value (%)
50
50
50
50
Flow Paths to Ditch Strips
>
Overlandflowfromstrip flowsintoditchstrip
2 1
3 1
A 1
5 1
6 9
7 9
S 9
Figure C-45. Source Parameters (7) - Flow Characteristics Tab.
C.6.2 Subsurface Parameters (Screen 8)
The predominating aquifer type is metamorphic and igneous. Figure C-46 shows the Subsurface
Parameters screen populated based on this information. Because only the general subsurface
environment is known, the subsurface parameters are all sampled from distributions specific to
the selected subsurface environment in the Monte Carlo simulation.
C-31
-------
IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Source Type (6)
Source Parameters (7)
Subsurface Parameters (8)
This screen allows you to enter or change the subsurface parameters.
L
You MUST select a Subsurface Environment. If you select'unknown'then the default values will be used for all parameters. In addition, you MAY enter value
parameter(s). Data sources are required.
Select the Subsurface Environment:
Metamorphic and Igneous
Parameter
Ground-water pH value (metals t
I Default
I Distribution
Depth to
I Distribution
lie conductivity (m/vr)
I Distribution
Regional hydraulic gradient
I Distribution
I Distribution
Value
Data Source
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Monte Carlo [see Note 1]
Figure C-46. Subsurface Parameters (8).
C.6.3 Infiltration Parameters (Screen 9)
Medium-grained soils are prevalent around the site. The site is located in Boston, MA.
Table C-20 contains values used for infiltration, runoff, precipitation, and evaporation rates.
Using Figure 6-7 from the IWEM Technical Background Document, Boston is located in climatic
zone Al. Montpelier, VT was selected as the representative location for that zone and all rates in
Table C-20 correspond to Montpelier, VT. A single rate was selected for each water flux type.
The infiltration and runoff rates correspond to the low-end value for asphaltic concrete pavement.
Evaporation rates are pan evaporation.
Table C-20. Rates for Infiltration, Runoff, Precipitation and Evaporation
Rate
Infiltration
Runoff
Precipitation
Evaporation
Value (m/yr)
0.12
0.60
0.88
0.57
Table in TBD
6-18
6-21
6-16
6-25
Figure C-47 shows the Infiltration screen populated based on this information. The recharge rate
is calculated for Boston, MA, and medium-grained soils.
C-32
-------
IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
Source Parameters (7)
Subsurface Parameters (8)
[Infiltration (9)|
Constil
Soil Data
Please select a soil to represent the
predominate soil type surrounding the
roadway for soil parameters and
recharge determination:
Cos.rse-gra.ined soil (sandy loam)
Fine-grained soil (silly clay loam)
Unknown soil type
Local Climate Data
Nearest Climate Center
Selected city Boston
View Cities List
MA
Recharge Rate (m/yr)
All Scenarios
-UserSpecified Infiltration Rates (rn/yr/unitarea)
Ditch Precip/Evap
Strip #
2
3
A
B
6
7
e
Type
Ernbankrnt
Paved
Paved
Median
Paved
Paved
Embankrm
Infiltration
Rate
0.1173
0.1173
0.1173
0.1173
0.1173
0.1173
0.1173
Source
User Entry
User Entry
User Entry
User Entry
User Entry
User Entry
User Entry
Default
Select
Select
Select
Select
Select
Select
Select
Runoff
Rate
0.6020
O.B020
0.6020
O.B020
0.6020
O.B020
0.6020
Predp and Evaporation in Ditches
Ditch
Strip
Precipitation
Rate (m/yr)
8763
8763
Evaporation
Rate (m/yr)
565
565
Figure C-47. Infiltration (9).
C.6.4 Constituent Parameters (Screens 10 and 11)
Reused materials containing arsenic HI were incorporated in all roadway layers except the
pavement and drains. Based on this information and the information in Table C-16, all layers in
strips 2 through 8, except layer 3 in strips 3, 4, 6, and 7 contain arsenic. Strips 1 and 9 are
ditches, which are always presumed to contain no teachable constituents. Table C-21 shows the
leachate and total (waste) concentrations for arsenic, and these are assumed to be the same for all
layers containing arsenic.
Table C-21. Constituent Concentrations for All Layers with Reused Material
Constituent
Arsenic III
Leachate (mg/L)
1.0
Waste (mg/kg)
0.05
Figure C-48 shows the Constituent List screen populated based on this information. Note that
columns for layer 3 are left blank, as that is a pavement layer with no arsenic.
C-33
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IWEMUser's Guide
Appendix C: Example Problems for Roadway Evaluation
iStrips
L
Ditches
Drains
(6) Paved Area [ (7) Paved Are a [ (8) Embankment
(9) Ditch
(1) Ditch ] (2) Embankment J
(3) Paved Area (A) Paved Area (5) Median
ConstituentlnitialConcentrations
>
Chemicals
CAS Number
22569-72-8
Constituent Name
Arsenic (III)
Layer! -Subgrade
Leach ate
(mg/L)
1
Total
(mg/kg)
0.05
Layer 2 - Base
Leach ate (mg/L)
1
Total (mg/kg)
0.05
Layer 3 - Pavement
Leach ate
(mg/L)
Total (mg/kg)
Figure C-48. Constituent List (10).
No site-specific information for constituent properties (Screen 11) is available, so the soil-water
partitioning coefficient (Kd) will be sampled from a distribution.
C.6.5 Reference Ground Water Concentrations (Screen 12)
The MCL for arsenic will be used as the standard to determine the performance of the roadway
with respect to the ground-water exposure pathway. Figure C-49 shows the Reference GW
Cone, screen populated based on this information.
Constituent List (10) ] Constituent Properties (11) J [Reference GW Cone" (12)j
InputE
Select a constituent from the grid, then the desired standard from the list. Click the "Apply Standards" button to save each selection.
Related
Constituents
>
Standards ft
Select Standar
(• MCL
r HBN-lnhala
(~ HBN-lnhala
r HBN- Ingest
r HBN -Ingest
r HBN-Derrn
r HBN-Derrn
r Other Stands
(~ Compare to
Select the desir
Constituent Standard
225E3-72-B Arsenic (III) MCL
o r 22569 -72 -8 Ars e n i c
Refer
j Cones
tion. Cancer
tion, Non-Cancer
ion. Cancer
ion, Non-Cancer
al. Cancer
al, Non-Cancer
»rd
all available standards
ed standard by clicking its radio
: (III)
ence Ground Water Exposure The exposure duration represents the
sntration (mg/L) Duration (yr) time period a person is assumed to
0.01
button. Click the 'Apply S
Qppr-jfjn QtRnrjard PfpQQ p"| fnr mr
information.
FrtitHRNs
r r
andards" button to save your selection.
re
Figure C-49. Reference Ground Water Concentration (12).
C.6.6 Results
As displayed on the Output Summary screen, IWEM determines that the roadway design with
industrial materials is appropriate—the estimated 90th percentile concentration for arsenic HI
was below the MCL. By design, IWEM predictions based on the substitution of national data for
key site-specific data (subsurface parameters and site-based partitioning coefficients) generate a
conservative result; the result errs on the side of environmental and human health protection.
C-34
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IWEM User's Guide Appendix C: Example Problems for Roadway Evaluation
The IWEM reports from this example are provided in Attachment C-l.
C.7 References
O'Donnell, J.B. 2009. Leaching of Trace Elements from Roadway Materials Stabilized with Fly
Ash -Madison. Master's thesis, University of Wisconsin-Madison.
U.S. EPA (Environmental Protection Agency). 2014. Industrial Waste Evaluation Model (IWEM)
v3.1 Technical Documentation. Draft. Office of Resource Conservation and Recovery,
Washington DC.
WAC. 2006. Wisconsin Administrative Code, Chapter NR 538.06(3). Industrial Byproduct
Characterization.
Wen, H. 2008. MnROAD High Carbon Fly Ash Research Project. Annual Report Submitted to
Minnesota Pollution Control Agency: Mn/DOT Office of Materials, 1400 Gervais
Avenue, Maplewood, MN 55190. July 11. Available at http://www.mrr.dot.state.mn.us/
research/pdf/2008MRRDOC026.pdf
C-35
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IWEM User's Guide Appendix C: Example Problems for Roadway Evaluation
[This page intentionally left blank.]
C-36
-------
IWEM User's Guide Attachment C-l: Sample Reports from Roadway Evaluation Examples
Attachment C-1. Sample Reports from
Roadway Evaluation Examples
Example Cl: Wisconsin State Highway 60, Lodi, WI C-l-3
Example C2: Wisconsin State Highway 57, Waldo, WI C-l-7
Example C3: MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3A: 10-m Well Distance C-l-11
Example C3B: 150-m Well Distance C-l-15
Example C4: MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4A: Segment A C-l-19
Example C4B: Segment B C-l-23
Example C4C: Segment C C-l-27
Example C5: Hypothetical Roadway, Boston, MA C-l-31
C-l-1
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IWEM User's Guide Attachment C-l: Sample Reports from Roadway Evaluation Examples
[This page intentionally left blank.]
C-l-2
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IWEMUser's Guide
Sample Report for Example Cl, Wisconsin State Highway 60, Lodi, WI
Example C1. Wisconsin State Highway 60, Lodi, WI (page 1 of 4)
Evaluation Results
Roadway Screening Results: Below Benchmark
Number of Flow and Transport Simulations: 1000
12/23/201304:21 A
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
WSH 60 Foundry Slag Test Section
WSH 60
Lodi
WI
4/30/2007
EPA User
none
Roadway Receptor Location Parameters
Parameter Value
Roadway segment length (m) 152
Angle between roadway and GWflow direction (°) 90
Well distance D(m) 24.8
Well distance L (m) 0
Receptor Well Location Setting
GW flow ^ /ingle
Well
Road
segment midpoint
Roadway Geometry Parameters
Strip 1 Type: Paved Area
Wdth (m): 10.4 Layer
Layer 4
LayerS
Layer 2
Layer 1
Type
Pavement
Base
Base
Subbase
Bulk Density (g/cmA31 Thickness (ml
2.85 .125
2.645 .115
2.195 .14
2.285 .84
Total Strip Thickness (m'ft.22
Hydraulic Conductivity (m/vr)
254.8
254.8
254.8
254.8
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-water pH value (metals only) Distribution Monte Carlo
Depth to watertable (m) Distribution Monte Carlo
Aquifer hydraulic conductivity (m/yr) Distribution Monte Carlo
Regional hydraulic gradient Distribution Monte Carlo
Aquifer thickness (m) Distribution Monte Carlo
Reference
[See IWEMTBD4.2.3.1]
[See IWEMTBD4.2.3.1]
[See IWEMTBD4.2.3.1]
[See IWEMTBD4.2.3.1]
[See IWEMTBD4.2.3.1]
C-l-3
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IWEMUser's Guide
Sample Report for Example Cl, Wisconsin State Highway 60, Lodi, WI
Example C1. Wisconsin State Highway 60, Lodi, WI (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter
Soil Type
Climate Center
Recharge Rate (m/yr)
Strip
1
Value
Coarse-grained soil (sandy loam)
Madison, WI
0.14
Infiltration Rate (m/yr)
0.0949
Runoff Rate (m/yr)
Constituent Concentrations
Strip
1
Layer
4
4
3
3
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
(No Constituents)
(No Constituents)
(No Constituents)
(No Constituents)
Cadmium
Selenium (IV)
Leachate
Concentration (mg/L)
.0321
.151
Total
Concentration (mg/kg)
.0397
.187
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name
RGC (mg/L)
RGC Based On
Kd*(L/kg) Decay Coeff* (1/yr) Leachate pH
Cadmium 5.00E-03 MCL
Selenium (IV) 5.00E-02 MCL
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
0
0
Detailed Constituent Results
Constituent Name
Cadmium
Selenium (IV)
Selected RGC
MCL
MCL
RGC (mg/L)
5.00E-03
5.00E-02
90th Percentile Receptor
Well Cone (mg/L)
.00259
.04444
Below Benchmark?
Yes
Yes
C-l-4
-------
IWEM User's Guide Sample Report for Example Cl, Wisconsin State Highway 60, Lodi, WI
Example C1. Wisconsin State Highway 60, Lodi, WI (page 3 of 4)
Constituent Standard Properties
Chemical Type
Molecular Weiqhl
Constituent Name
Cadmium
Physical Property
(g/mol)
CAS ID
7440-43-9
Value
Metal
112.41
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherntiSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 5.00E-03 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
C-l-5
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IWEM User's Guide Sample Report for Example Cl, Wisconsin State Highway 60, Lodi, WI
Example C1. Wisconsin State Highway 60, Lodi, WI (page 4 of 4)
Constituent Name CAS ID
Selenium (IV) 10026-03-6
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 78.96
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsothernteSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 5.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-6
-------
IWEMUser's Guide
Sample Report for Example C2, Wisconsin State Highway 57, Waldo, WI
Example C2. Wisconsin State Highway 57, Waldo, WI (page 1 of 4)
Tier 2 Evaluation Results
Roadway Screening Results: Protective
Number of Flow and Transport Simulations: 10000
08/31/2012 09:16 P
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
WSH 57 Foundry Sand Fill Analysis
WSH 57
Waldo and Random Lake
WI
4/30/2007
EPA Uset-
none
Roadway Receptor Location Parameters
Parameter Value
Roadway segment length (m) 1829
Angle between roadway and GWflow direction (°) 130
Well distance D (m) 61
Well distance L (m) 6.1
Receptor Well Location Setting
Well
GWflow
Roadway Geometry Parameters
Strip 1 Type: Paved Area Width (m):
1 [Lfver
Layers
Layer 2
Layer 1
Type Bulk Density fg/cmA31
Pavement 2.85
Subbase 2.645
Fill 1.89
Total Strip Thickness (m):
Thickness (m)
.15
.2
.914
1.264
Hydraulic Conductivity fm/vr)
1.74
1.74
1.74
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to water table (m) Distribution
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Data Source
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
C-l-7
-------
IWEM User's Guide Sample Report for Example C2, Wisconsin State Highway 57, Waldo, WI
Example C2. Wisconsin State Highway 57, Waldo, WI (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter Value
Soil Type Fine-grained soil (silty clay loam)
Climate Center Madison, WI
Recharge Rate (m/yr) 0.0686
Strip Infiltration Rate (m/yr) Runoff Rate (m/yr)
1 0.3525
Constituent Concentrations
Strip
1
Layer
3
3
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
(No Constituents)
(No Constituents)
Barium
Arsenic (III)
Leachate
Concentration (mg/L)
.27
.05
Total
Concentration (mg/kg)
8
10.6
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name RGC (mg/L) RGC Based On Kd* (L/kg) Decay Coeff* (1/yr) Leachate pH
Barium 2 MCL 0
Arsenic (III) .01 MCL 0
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Barium
Arsenic (III)
Selected RGC
MCL
MCL
RGC (mg/L)
2
.01
90th Percentile Receptor
Well Cone (mg/L)
.2158
.04237
Protective?
Yes
No
C-l-8
-------
IWEM User's Guide Sample Report for Example C2, Wisconsin State Highway 57, Waldo, WI
Example C2. Wisconsin State Highway 57, Waldo, WI (page 3 of 4)
Constituent Standard Properties
Chemical Type
Molecular Weight
Constituent Name
Barium
Physical Property
(g/mol)
CAS ID
7440-39-3
Value
Metal
137.33
Data Source
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherntdSEPA, 2003
Reference Groundwater Concentration Standard Value Data Source
Maximum Contamination Level (mg/L) 2 USEPA, 2000h
HBN-lngestion, Non-Cancer (mg/L) 1.7 USEPA, 2001 b
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
Reference Dose (mg/kg-day) .07 USEPA, 2001 b
Carcinogenic Slope Factor-Oral (1/mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1/mg/kg-day)
Reference Concentration (mg/mA3)
C-l-9
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IWEM User's Guide Sample Report for Example C2, Wisconsin State Highway 57, Waldo, WI
Example C2. Wisconsin State Highway 57, Waldo, WI (page 4 of 4)
Constituent Name CAS ID
Arsenic (III) 22569-72-8
Physical Property Value Data Source
Chemical Type Metal
Molecular Weight (g/mol) 74.9216
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) ' 1000000
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherrrtiSEPA, 2003
Reference Groundwater Concentration Standard Value Data Source
Maximum Contamination Level (mg/L) .01
HBN-lngestion, Non-Cancer (mg/L) .0073
HBN-lngestion, Cancer (mg/L) .000064
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
Reference Dose (mg/kg-day) .0003
Carcinogenic Slope Factor-Oral (1/mg/kg-day) 1.5
Carcinogenic Slope Factor-Inhalation (1/mg/kg-day)
Reference Concentration (mg/mA3)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
USEPA. 2000h. Code of Federal Regulations, National Primary Drinking Water Regulations, CFR 40, Part 141, Section 32.
www.epa.gov/safewater/regs/cfr141.pdf.
USEPA. 2001 b. Integrated Risk Information System (IRIS). National Center for Environmental Assessment, Office of Research and Development,
Washington, DC. http://www.epa.gov/iris/
C-l-10
-------
IWEMUser's Guide
Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3A. MnROAD Low Volume Road, Monticello, MN, 10-m Well Distance (page 1 of 4)
Evaluation Results
Roadway Screening Results: Exceeds Benchmark
Number of Flow and Transport Simulations: 10000
12/23/2013 05:34 A
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
MnRoad Test Section 79
Low Volume Roadway
Monticello
MN
May 2010
EPA user
none
Roadway Receptor Location Parameters
Parameter
Roadway segment length (m)
Angle between roadway and GWfiow direction
Well distance D (m)
Well distance L (m)
Receptor Well Location Setting
GWfiow
Roadway Geometry Parameters
Strip 1 Type: Paved Area Width (m):
Layer Type Bulk Density (g/cmA31 Thickness frn)
Layer 2 Pavement 2.31 .102
Layer 1 Base 1.99 .203
Total Strip Thickness (m):305
Well
segment midpoint
Hydraulic Conductivity fm/vr)
3.2
13.6
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to water table (m) 1.35
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD 4.2.3.1]
Monitoring well data near Section 79
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
C-l-11
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IWEM User's Guide Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3A. MnROAD Low Volume Road, Monticello, MN, 10-m Well Distance (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter Value
Soil Type Fine-grained soil (silty clay loam)
Climate Center St. Cloud, MN
Recharge Rate (m/yr) 0.0554
Strip Infiltration Rate fm/yr) Runoff Rate (m/yr)
1 0.1825
Constituent Concentrations
Strip
1
Layer
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
Cadmium
Arsenic (III)
Leachate
Concentration (mg/L)
.0052
.0692
Total
Concentration (mg/kg)
.76
3.4
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name RGC (mg/L) RGC Based On Kd* (L/kg) Decay Coeff* (1/yr) Leachate pH
Cadmium 4.00E-03 User Defined 0
Arsenic (III) 1.00E-02 MCL 0
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Cadmium
Arsenic (III)
Selected RGC
User Defined
MCL
RGC (mg/L)
4.00E-03
1.00E-02
90th Percentile Receptor
Well Cone (mg/L)
.004797
.05236
Below Benchmark?
No
No
C-l-12
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IWEM User's Guide Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3A. MnROAD Low Volume Road, Monticello, MN, 10-m Well Distance (page 3 of 4)
Constituent Standard Properties
Constituent Name CAS ID
Cadmium 7440-43-9
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 112.41
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption Isothernt^SEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 5.00E-03 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
C-l-13
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IWEM User's Guide Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3A. MnROAD Low Volume Road, Monticello, MN, 10-m Well Distance (page 4 of 4)
Constituent Name CAS ID
Arsenic (III) 22569-72-8
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 74.9216
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherrrtiSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 1.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-14
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IWEMUser's Guide
Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3B. MnROAD Low Volume Road, Monticello, MN, 150-m Well Distance (page 1 of 4)
Evaluation Results
Roadway Screening Results: Below Benchmark
Number of Flow and Transport Simulations: 10000
12/23/2013 06:00 A
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
MnRoad Test Section 79
Low Volume Roadway
Monticello
MN
May 2010
EPA user
none
Roadway Receptor Location Parameters
Parameter Value
Roadway segment length (m) 115
Angle between roadway and GWflow direction (°) 90
Well distance D (m) 150
Well distance L(m) 0
Receptor Well Location Setting
GWflow
Roadway Geometry Parameters
Strip 1 Type: Paved Area Width (m)
Layer Type Bulk Density fg/crnA3) Thickness fml
Layer 2 Pavement 2.31 .102
Layer 1 Base 1.99 .203
Total Strip Thickness (m):305
Well
Road
segment midpoint
Hydraulic Conductivity [m/vr'l
3.2
13.6
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-waterpH value (metals only) Distribution
Depth to water table (m) 1.35
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD 4.2.3.1]
Monitoring well data near Section 79
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
C-l-15
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IWEM User's Guide Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3B. MnROAD Low Volume Road, Monticello, MN, 150-m Well Distance (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter Value
Soil Type Fine-grained soil (silty clay loam)
Climate Center St. Cloud, MN
Recharge Rate (m/yr) 0.0554
Infiltration Rate (rn/yr) Runoff Rate (rn/yr)
0.1825
Constituent Concentrations
Strip
1
Layer
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
Cadmium
Arsenic (III)
Leachate
Concentration (mg/L)
.0052
.0692
Total
Concentration (mg/kg)
.76
3.4
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name RGC (mg/L) RGC Based On Kd* (L/kg) Decay Coeff* (1/yr) Leachate pH
Cadmium 4.00E-03 User Defined 0
Arsenic (III) 1.00E-02 MCL 0
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Cadmium
Arsenic (III)
Selected RGC
User Defined
MCL
RGC (mg/L)
4.00E-03
1.00E-02
90th Percentile Receptor
Well Cone (mg/L)
.0008831
.008973
Below Benchmark?
Yes
Yes
C-l-16
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IWEM User's Guide Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3B. MnROAD Low Volume Road, Monticello, MN, 150-m Well Distance (page 3 of 4)
Constituent Standard Properties
Chemical Type
Molecular Weight
Constituent Name
Cadmium
Physical Property
(g/mol)
CAS ID
7440-43-9
Value
Metal
112.41
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherntdSEPA, 2003
| Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 5.00E-03 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
C-l-17
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IWEM User's Guide Sample Report for Example C3, MnROAD Low Volume Road, Monticello, MN, Multiple Well Distances
Example C3B. MnROAD Low Volume Road, Monticello, MN, 150-m Well Distance (page 4 of 4)
Constituent Name CAS ID
Arsenic (III) 22569-72-8
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 74.9216
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsothernMSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 1.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-18
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WEM User's Guide
Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4A. MnROAD Low Volume Road, Monticello, MN, Segment A (page 1 of 4)
Evaluation Results
Roadway Screening Results: Below Benchmark
Number of Flow and Transport Simulations: 10000
12/23/201306:26 A
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
MnROAD Test Section 79
Low Volume Roadway
Monticello
MN
May 2010
EPA User
Segment A
Roadway Receptor Location Parameters
Parameter Value
Roadway segment length (m) 100
Angle between roadway and GWfiow direction (°) 45
Well distance D (m) 85.4
WelldistanceL(m) 35.4
Receptor Well Location Setting
GW flow
Well
Road
segment
midpoint
Roadway Geometry Parameters
Strip 1 Type: Paved Area Wdth (m):
8.5 Layer Type Bulk Density (ci/cmA3) Thickness fm)
Layer 2 Pavement 2.31 .102
Layer 1 Base 1.99 .203
Total Strip Thickness (m):305
Hydraulic Conductivity (rn/yr)
3.15
13.6
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to water table (m) 1.35
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD4.2.3.1]
Monitoring well data near Section 79
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
C-l-19
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4A. MnROAD Low Volume Road, Monticello, MN, Segment A (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter Value
Soil Type Fine-grained soil (silty clay loam)
Climate Center St. Cloud, MN
Recharge Rate (m/yr) 0.0554
Infiltration Rate (m/yr) Runoff Rate (m/yr)
0.1825
Constituent Concentrations
Strip
1
Layer
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
Cadmium
Arsenic (II I)
Leachate
Concentration (mg/L)
.0052
.0692
Total
Concentration (mg/kg)
.76
3.4
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name RGC (mg/L) RGC Based On Kd* (L/kg) Decay Coeff* (1/yr) Leachate pH
Cadmium 4.00E-03 User Defined 0
Arsenic (III) 1.00E-02 MCL 0
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Cadmium
Arsenic (III)
Selected RGC
User Defined
MCL
RGC (mg/L)
4.00E-03
1.00E-02
90th Percentile Receptor
Well Cone (mg/L)
.000000001938
.00000002005
Below Benchmark?
Yes
Yes
C-l-20
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4A. MnROAD Low Volume Road, Monticello, MN, Segment A (page 3 of 4)
Constituent Standard Properties
Constituent Name CAS ID
Cadmium 7440-43-9
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 112.41
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) ' 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherrrtiiSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 5.00E-03 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
C-l-21
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4A. MnROAD Low Volume Road, Monticello, MN, Segment A (page 4 of 4)
Constituent Name CAS ID
Arsenic (III) 22569-72-8
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 74.9216
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) ' 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherntiSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 1.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-22
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WEM User's Guide
Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4B. MnROAD Low Volume Road, Monticello, MN, Segment B (page 1 of 4)
12/23/201 3 06:45 A
Evaluation Results
Roadway Screening Results: Exceeds Benchmark
Number of Flow and Transport Simulations: 10000
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
MnROAD Test Section 79
Low Volume Roadway
Monticello
MN
May 2010
EPA User
Segment B
Roadway Receptor Location Parameters
Parameter Value
Roadway segment length (rn) 100
Angle between roadway and GWflow direction (°) 90
Well distance D(m) 70.7
Well distance L (m) 0
Receptor Well Location Setting
GWflow A x^ngle
Road
t segment
midpoint
WelM
Roadway Geometry Parameters
Strip 1 Type: Paved Area Width (m):
Layer Type Bulk Density fg/cmA31 Thickness (ml
Layer2 Pavement 2.31 .102
Layer 1 Base 1.99 .203
Total Strip Thickness (m):305
Hydraulic Conductivity fm/vrl
3.15
13.6
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to watertable (m) 1.35
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD4.2.3.1]
Monitoring well data near Section 79
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
C-l-23
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4B. MnROAD Low Volume Road, Monticello, MN, Segment B (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter Value
Soil Type Fine-grained soil (silty clay loam)
Climate Center St. Cloud, MN
Recharge Rate (m/yr) 0.0554
Strip Infiltration Rate fm/yr) Runoff Rate (m/yr)
1 0.1825
Constituent Concentrations
Strip
1
Layer
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
Cadmium
Arsenic (III)
Leachate
Concentration (mg/L)
.0052
.0692
Total
Concentration (mg/kg)
.76
3.4
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name RGC (mg/L) RGC Based On Kd* (L/kg) Decay Coeff* (1/yr) Leachate pH
Cadmium 4.00E-03 User Defined 0
Arsenic (III) 1.00E-02 MCL 0
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Cadmium
Arsenic (III)
Selected RGC
User Defined
MCL
RGC (mg/L)
4.00E-03
1.00E-02
90th Percentile Receptor
Well Cone (mg/L)
.001712
.01625
Below Benchmark?
Yes
No
C-l-24
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WEM User's Guide
Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4B. MnROAD Low Volume Road, Monticello, MN, Segment B (page 3 of 4)
Constituent Standard Properties
Chemical Type
Molecular Weight
Constituent Name
Cadmium
Physical Property
(g/mol)
CAS ID
7440-43-9
Value
Metal
112.41
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherrMBEPA, 2003
CambridgeSoft Corporation, 2001
Reference Groundwater Concentration Property
Value
Reference
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
5.00E-03
USEPA, 2013
C-l-25
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4B. MnROAD Low Volume Road, Monticello, MN, Segment B (page 4 of 4)
Constituent Name CAS ID
Arsenic (III) 22569-72-8
Physical Property Value Reference
Chemical Type Metal
Molecular Weight (g/mol) 74.9216
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherntiSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 1.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)"was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-26
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WEM User's Guide
Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4C. MnROAD Low Volume Road, Monticello, MN, Segment C (page 1 of 4)
Evaluation Results
Roadway Screening Results: Below Benchmark
Number of Flow and Transport Simulations: 10000
12/23/2013 07:05 A
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
MnROAD Test Section 79
Low Volume Roadway
Monticello
MN
May 2010
EPA User
Segment C
Roadway Receptor Location Parameters
Parameter
Roadway segment length (m)
Angle between roadway and GWflow direction (°)
Well distance D (m)
Well distance L (m)
Receptor Well Location Setting
.Well i
Roadway Geometry Parameters
Strip 1 Type: Paved Area Width (m):
Layer Type Bulk Density fg/crnA3) Thickness (ml
Layer 2 Pavement 2.31 .102
Layer 1 Base 1.99 .203
Total Strip Thickness (m):305
GW flow
Hydraulic Conductivity frn/vr)
3.15
13.6
Subsurface Parameters
Subsurface Environment Till over Sedimentary Rock
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to watertable (m) 1.35
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD4.2.3.1]
Monitoring well data near Section 79
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
Monte Carlo [See IWEM TBD4.2.3.1]
C-l-27
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4C. MnROAD Low Volume Road, Monticello, MN, Segment C (page 2 of 4)
Infiltration, Regional Soil, and Climate Parameters
Parameter Value
Soil Type Fine-grained soil (silty clay loam)
Climate Center St. Cloud, MN
Recharge Rate (m/yr) 0.0554
Infiltration Rate (m/yr) Runoff Rate (m/yr)
0.1825
Constituent Concentrations
Strip
1
Layer
2
2
1
1
Chemical Name
(No Constituents)
(No Constituents)
Cadmium
Arsenic (III)
Leachate
Concentration (mg/L)
.0052
.0692
Total
Concentration (mg/kg)
.76
3.4
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
Constituent Name RGC (mg/L) RGC Based On Kd* (L/kg) Decay Coeff* (1/yr) Leachate pH
Cadmium 4.00E-03 User Defined 0
Arsenic (III) 1.00E-02 MCL 0
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Cadmium
Arsenic (III)
Selected RGC
User Defined
MCL
RGC (mg/L)
4.00E-03
1.00E-02
90th Percentile Receptor
Well Cone (mg/L)
.000000001938
.00000002005
Below Benchmark?
Yes
Yes
C-l-28
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WEM User's Guide
Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4C. MnROAD Low Volume Road, Monticello, MN, Segment C (page 3 of 4)
Constituent Standard Properties
Chemical Type
Molecular Weiqhl
Constituent Name
Cadmium
Physical Property
(g/mol)
CAS ID
7440-43-9
Value
Metal
112.41
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) ' 1000000
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsothemteSEPA, 2003
CambridgeSoft Corporation, 2001
Reference Groundwater Concentration Property
Value
Reference
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
5.00E-03
USEPA, 2013
C-l-29
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WEM User's Guide Sample Report for Example C4, MnROAD Low Volume Road, Monticello, MN, Multiple Segments
Example C4C. MnROAD Low Volume Road, Monticello, MN, Segment C (page 4 of 4)
Constituent Name CAS ID |
Arsenic (III) 22569-72-8
| Physical Property Value Reference |
Chemical Type Metal
Molecular Weight (g/mol) 74.9216
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherrrtiSEPA, 2003
| Reference Groundwater Concentration Property Value Reference |
Maximum Contamination Level (mg/L) 1.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-30
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IWEMUser's Guide
Sample Report for Example C5, Hypothetical Road Segment, Boston, MA
Example C5. Hypothetical Road Segment, Boston, MA (page 1 of 5)
Evaluation Results
Roadway Screening Results: Below Benchmark
Number of Flow and Transport Simulations: 10000
12/23/2013 03:29 A
Facility Identification
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
Appendix C Example 5- Verification Problem
Roadway Receptor Location Parameters
Parameter Value
Roadway segment length (m) 120
Angle between roadway and GWfiow direction (°) 90
Well distance D (m) 30.5
Well distance L(m) 0
Roadway Geometry Parameters
Strip 1 Type: Ditch Width (m):
Strip 2 Type: Embankment Wdth(m):
Strip 3 Type: Paved Area Wdth(m):
Strip 4 Type: Paved Area Wdth(m):
Strips Type: Median Wdth(m):
3 Layer
Layer 1
3 Layer
Layer 2
Layer 1
3 Layer
Layers
Layer 2
Layer 1
3 Layer
Layers
Layer 2
Layer 1
3 Layer
Layer 2
Layer 1
Type
Fill
Type
Fill
Fill
Type
Pavement
Base
Sub grade
Type
Pavement
Base
Sub grade
Type
Fill
Fill
Bulk Density (g/cmA3) Thickness frnl
2 .45
Total Strip Thickness (m):.45
Bulk Density (g/cmA3i Thickness (ml
2 .75
2 .6
Total Strip Thickness (m)1. 35
Bulk Density (q/cmA3) Thickness (m)
2 .3
2 .3
2 .6
Total Strip Thickness (m):1.2
Bulk Density (g/cmA3i Thickness (ml
2 .3
2 .3
2 .6
Total Strip Thickness (m):1.2
Bulk Density (g/cmA3) Thickness frnl
2 .75
2 .6
Total Strip Thickness (m)t. 35
Receptor Well Location Setting
GWfiow .. /^ngle
jE^\^ * Well
^^ segment midpoint
Hydraulic Conductivity fm/vrl
13.6
Hydraulic Conductivity fm/vrl
13.6
13.6
Hydraulic Conductivity (m/yr)
3.6
13.6
13.6
Hydraulic Conductivity fm/vrl
3.6
13.6
13.6
Hydraulic Conductivity fm/vrl
13.6
13.6
C-l-31
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IWEMUser's Guide
Sample Report for Example C5, Hypothetical Road Segment, Boston, MA
Example C5. Hypothetical Road Segment, Boston, MA (page 2 of 5)
Strips Type: Paved Area Width (m):
3 Layer
Layer
Layer
Layer
3
2
1
Type
Pavement
Base
Subgrade
Bulk Density (g/cmA3)
2
2
2
Thickness (m)
.3
.3
.6
Hydraulic Conductivity
3.16
13.6
13.6
(m/yr)
Total Strip Thickness (m):1.2
Strip? Type: Paved Area Width (m):
3 Layer
Layer
Layer
Layer
3
2
1
Type
Pavement
Base
Subgrade
Bulk Density (g/cmA3)
2
2
2
Thickness (m)
.3
.3
.6
Hydraulic Conductivity
3.16
13.6
13.6
(m/vr)
Total Strip Thickness (m):1.2
Strips Type: Embankment Width (m):
3 Layer
Layer
Layer
2
1
Type
Fill
Fill
Bulk Density (q/cmA3)
2
2
Thickness (m)
.75
.6
Hydraulic Conductivity
13.6
13.6
(m/yr)
Total Strip Thickness (m)1.35
Stripi Type: Ditch Width (m):
3 Layer
Layer
1
Type
Fill
Bulk Density (g/cmA3)
2
Thickness (m)
.45
Hydraulic Conductivity
13.6
fm/vrt
Total Strip Thickness (m):.45
Ditch Characteristics
Strip Manning's n
1 .016
9 .016
Slope (m/rrrt
1E-08
1E-08
Max Depth (m)
1
1
Gutter?
Y
Y
Between Strips
2&3
7&8
Drain Characteristics
Drain Drains Strips
Drain 1
Drain 2
3.4
6,7
Above Layer
1
1
Drains To
1
9
Thickness (m)
.15
.15
Hydraulic Conductivity fm/yr)
1 .095E+07
1 .095E+07
Bulk Density (g/cmA3)
2
2
Flow Characteristics
Ditch Strip 1 receives roadway runoff from strips: 2, 3, 4, 5
Percent of roadway runoff that reaches ditch strip 1: 50.0
Ditch Strip 9 receives roadway runoff from strips: 6, 7, 8
Percent of roadway runoff that reaches ditch strip 9: 50.0
Percent of flow in Drain 1 that reaches ditch strip 1: 50.0
Percent of flow in Drain 2 that reaches ditch strip 9: 50.0
Subsurface Parameters
Subsurface Environment
Parameter
Metamorphic and Igneous
Value
Ground-water pH value (metals only) Distribution
Depth to water table (m) Distribution
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
C-l-32
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IWEMUser's Guide
Sample Report for Example C5, Hypothetical Road Segment, Boston, MA
Example C5. Hypothetical Road Segment, Boston, MA (page 3 of 5)
Infiltration, Regional Soil, and Climate Parameters
Parameter
Soil Type
Climate Center
Recharge Rate (m/yr)
Strip
2
3
4
5
6
7
8
Ditch
Strip 1
Strip 9
Value
Medium-grained soil (silt loam)
Boston, MA
0.2332
Infiltration Rate (m/yr)
0,1173
0.1173
0.1173
0.1173
0.1173
0.1173
0.1173
Precipitation Rate (m/vrl
0.8763
0.8763
Runoff Rate (m/yr)
0.602
0.602
0.602
0.602
0.602
0.602
0.602
Evaporation Rate (m/vr)
0.565
0.565
C-l-33
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IWEMUser's Guide
Sample Report for Example C5, Hypothetical Road Segment, Boston, MA
Example C5. Hypothetical Road Segment, Boston, MA (page 4 of 5)
Constituent Concentrations
Strip
1
2
3
4
5
6
7
8
9
Drain
Drain 1
Drain 2
Ditch
Strip 1
Strip 9
Layer
1
2
1
3
2
1
3
2
1
2
1
3
2
1
3
2
1
2
1
1
Chemical Name
(No Constituents)
Arsenic (III)
Arsenic (III)
(No Constituents)
Arsenic (III)
Arsenic (III)
(No Constituents)
Arsenic (III)
Arsenic (III)
Arsenic (III)
Arsenic (III)
(No Constituents)
Arsenic (III)
Arsenic (III)
(No Constituents)
Arsenic (III)
Arsenic (III)
Arsenic (III)
Arsenic (III)
(No Constituents)
Arsenic (III)
Arsenic (III)
Arsenic (III)
Arsenic (III)
Leachate
Concentration (mg/L)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Total
Concentration (mg/kg)
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
.05
Inflow Concentration Cma/LI
.05
.05
Constituent Reference Ground water Concentrations (RGC) and User-Defined Properties
Constituent Name
RGC (mg/L)
RGC Based On
Kd*(L/kg) Decay Coeff* (1 /yr) Leachate pH
Arsenic (III) 1.00E-02 MCL
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Selected RGC
RGC (mg/L)
90th Percent!Ie Receptor
Well Cone (mg/L)
Below Benchmark?
Arsenic i
MCL
1.00E-02
.0064318
Yes
C-l-34
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IWEM User's Guide Sample Report for Example C5, Hypothetical Road Segment, Boston, MA
Example C5. Hypothetical Road Segment, Boston, MA (page 5 of 5)
Constituent Standard Properties
Chemical Type
Molecular Weight
Constituent Name
Arsenic (III)
Physical Property
(g/mol)
CAS ID
22569-72-8
Value
Metal
74.9216
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption IsotherrMSEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 1.00E-02 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July
2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April
2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening
Levels Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013.Note: Surrogate
values were applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was
applied to 22569-72-8 Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9
Chlordane. RSL value for "7782-49-2 Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
C-l-35
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IWEM User's Guide Attachment C-l: Sample Reports from Roadway Evaluation Examples
[This page intentionally left blank.]
C-l-36
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IWEM User's Guide Appendix D: Example Problem for Structural Fill Evaluation
Appendix D: Example Problem for Structural Fill Evaluation
Project files corresponding to this example may be found in either
• C:\Users\Public\Documents\IWEM\SampleData\ Appendix_D_Structural_Fill or
• C :\Users\[your user name]\Documents\IWEM\SampleData\ Appendix_
D_Structural_Fill.
D. 1 Landscape Alteration Using Coal Ash as Compacted Fill Material
This example was adapted and modified from the (EPRI, 1990) and evaluates an area near an
industrial park north west of Minneapolis, MN, where ash fill is used to level an undeveloped
section of the park. The area is approximately 15,000 m2 and was excavated to remove desirable
soils for other uses. In order to prepare the site for possible future development, the area needed
to be leveled. The excavated area was filled with about 40,000 m3 of coal ash from nearby coal-
fired electrical generation stations over a two year period. Most of the ash fill, which is has a
fairly uniform 1.5-2.1 m thickness after compaction, is covered by a thin layer of topsoil which
aids in sustaining vegetation and preventing erosion.
The regional geology is dominated by a glacial end moraine. The surficial geology in the vicinity
of the site is comprised of an undulating glacial outwash plain made of principally of fine sand.
Borings indicate that the surface stratum consists of light brown sandy loam and that the water
table was approximately 4 m below ground surface beneath the fill area, and 2.1 m beneath the
ash fill. Groundwater monitoring provides water table elevation in and around the site to
establish an estimate of hydraulic gradient.
Physical properties of the ash and underlying soils were ascertained through laboratory test
methods. Leaching concentrations were derived from lysimeters installed in the ash fill. Total
concentrations were obtained from laboratory tests. The primary constituents of considered in
this exercise are barium and molybdenum. The screening levels will be detection limits for both
constituents. The following tables summarize the input parameters. No sorption data was
available so default MINTEQA2 isotherms will be used. Detection limits will serve as the
exposure standard and we assume a 1-year exposure duration. The following parameters were
used within the model to define the use scenario (in order of entry):
• Source Type: Structural fill
• Source Parameters:
- Distance to well: 30 m (hypothetical distance to compliance point)
- Structural fill depth: 1.8 m (average depth of soil borings)
- Structural fill area: 15,000 m2
- Depth of base of SF below ground surface: 1.8 m (fill is level with ground)
- Effective bulk density: 1.47 g/cm3 (maximum value obtained in laboratory testing)
- Effective hydraulic conductivity: 3.16 m/yr (compacted ash value obtained in
laboratory testing)
- Volume fraction occupied by teachable material: 1 m3/m3 (entire fill is coal ash)
D-l
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IWEMUser's Guide
Appendix D: Example Problem for Structural Fill Evaluation
Subsurface parameters used known values where provided and the remainder were set
to model defaults:
- Subsurface environment: outwash
- Groundwater pH: default distribution Depth to water table: 4.0 m (soil borings)
- Hydraulic conductivity: default distribution
- Regional hydraulic gradient: 0.035 m/m (approximation from water table elevation
contours)
- Aquifer thickness: default distribution
Infiltration parameters:
- Site-specific infiltration rate: 0.17 m/yr (site estimate)
- Soil type: sandy loam (coarse-grained soil; most common in Madison, WI)
- Climate center: St. Cloud, MN (nearest climate center to site)
- Recharge Rate: 0.083 m/yr (based on soil type and climate center)
Constituent List:
- Barium, molybdenum
- Barium leachate concentration: 0.065 mg/L (average concentration from lysimeter
measurements)
- Barium total concentration: 0.251 mg/kg (laboratory leaching tests)
- Molybdenum leachate concentration: 0.38 mg/L (average concentration from
lysimeter measurements)
- Molybdenum total concentration: 0.05 mg/kg (laboratory leaching tests)
Constituent Properties:
- Chemical-specific decay rate: NA for metals
- Soil-water partition coefficient: selected from isotherms generated by the
MINTEQA2 geochemical speciation model
Reference Ground Water Concentrations: based on detection limits and entered as
"other standard":
Constituent
Barium
Molybdenum
Other Standard
RGC
(mg/L)
0.009
0.05
Exposure Duration
(yr)
1
1
This example results in a finding that the structural fill is an appropriate management practice of
coal ash under this scenario (i.e., the ground water concentrations of barium and molybdenum
under this scenario are below their respective detection limits). The IWEM output report for this
scenario is provided in Attachment D-l.
D.2 References
EPRI (Electric Power Research Institute), 1990. Environmental Performance Assessment of Coal
Ash Use Sites: Little Canada Structural Ash Fill. EPRI EN-6532. Prepared for EPRI by
Radian Corporation, Austin, TX.
D-2
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IWEM User's Guide Attachment D-l: Sample Report from Structural Fill Evaluation Example
Attachment D-1. Sample Report from
Structural Fill Evaluation Example
D-l-l
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IWEM User's Guide Attachment D-l: Sample Report from Structural Fill Evaluation Example
[This page intentionally left blank.]
D-l-2
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IWEMUser's Guide
Sample Report from Structural Fill Evaluation Example
01/26/2015 10:31 AM
Evaluation Results
Structural Fill Screening Results: No Benchmarks Exceeded
Number of Flow and Transport Simulations: 10000
Facility Type
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional infomiation
Structural Fill
Ash Structural Fill
May5, 2014
EPA
Screening for detections at 30m down gradient
Structural Fill Parameters
Parameter Value
Distance to well (m) 30
Structural fill depth (m) 1.8
Structural fill area (mA2) 15000
Depth of base of the SF below ground surface (m) 1.8
Effective bulk density (g/cmA3) 1.47
Effective hydraulic conductivity (m/yr) 3.16
Volume fraction occupied by leachable material 1
Subsurface Parameters
Subsurface Environment Outwash
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to watertable (m) 4
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient .035
Aquifer thickness (m) Distribution
Reference
Monte Carlo [See IWEM TBD 4.2.3.1]
Soil borings
Monte Carlo [See IWEM TBD 4.2.3.1]
Approximated from watertable elevation contours
Monte Carlo [See IWEM TBD 4.2.3.1]
Regional Soil and Climate Parameters
Parameter
Soil Type
Climate Center
Recharge Rate (m/yr)
Infiltration Rate (m/yr)
Value
Coarse-grained soil(sandy loam)
St. Cloud, MN
0.0831
0.17
D-l-3
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IWEM User's Guide Sample Report from Structural Fill Evaluation Example
Constituent Reference Groundwater Concentrations (RGC) and User-Defined Properties
RGC Kd* Decay Coeff* Leachate Total
Constituent Name (mg/L) RGC Based On (L/kg) (1/yr) Cone (mg/L) Cone (mg/kg)
Molybdenum 5.00E-02 HBN - Inhalation, Cancer .38 .05
Barium 9.00E-03 HBN - Inhalation, Cancer .065 .251
*lf a site-specific value was entered by the user, it will be displayed here;
otherwise the model used the constituent properties listed at the end of the report.
Detailed Constituent Results
Constituent Name
Molybdenum
Barium
Leachate
Cone. (mg/L)
0.38
0.065
DAF
(mg/L)
7.8
7.4
Selected RGC
HBN - Inhalation, CancerS
HBN - Inhalation, CancerQ
RGC
(mg/L)
OOE-02
OOE-03
90th Pctile Exp
Cone. (mg/L)
.04882
.008765
Below
Benchmark?
Yes
Yes
Constituent Standard Properties
c
c
Chemical Type
Molecular Weight
Constituent Name
Molybdenum
Physical Property
(g/mol)
CAS ID
7439-98-7
Value
Metal
95.9
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption Isotherms USEPA, 2003
| Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L) 5 OOE-02 Detection Limit
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
D-l-4
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IWEM User's Guide Sample Report from Structural Fill Evaluation Example
\ Constituent Name
Barium
I Physical Property
Chemical Type
Molecular Weight (q/mol)
CAS ID
7440-39-3
Value
Metal
137.33
Reference
Log Koc: distribution coefficient for organic carbon
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L) 1000000 CambridgeSoft Corporation, 2001
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's Law constant (atm-mA3/mol)
Kd: solid/liquid partitioning coefficient (L/kg) MINTEQA2 Industrial D Sorption Isotherms USEPA, 2003
Reference Groundwater Concentration Property Value Reference
Maximum Contamination Level (mg/L) 2.00E+00 USEPA, 2013
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation. Non-Cancer (mg/L)
HBN-lnhalatioa Cancer (mg/L) 9 OQE-03 Detection Limit
HBN-Dermal, Non-Cancer (mg/L)
HBN-Dermal, Cancer (mg/L)
References
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July 2001.
USEPA. 2003. EPA's Composite Model for Leachate Migration with Transformation Products (EPACMTP), Parameters/Data Background Document. April 2003.
U.S. EPA (Environmental Protection Agency). 2013. Regional Screening Levels for Chemical Contaminants at Superfund Sites: Regional Screening Levels
Generic Tables. Developed in cooperation with Oak Ridge National Laboratory. Available at
http://wvAw.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm. Accessed November 2013. Note: Surrogate values were
applied for four IWEM MCLs where an exact match was not available. RSL value for "7440-38-2 Arsenic, Inorganic (10 ug/L)" was applied to 22569-72-8
Arsenic (III) and 15584-04-0 Arsenic (V). RSL value for "12789-03-6 Chlordane ( 2 ug/L)" was applied to 57-74-9 Chlordane. RSL value for "7782-49-2
Selenium (50 ug/L)" was applied to 10026-03-6 Selenium (IV).
D-l-5
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