United Stales
Environmental Protected
Agency
<&EPA Industrial Waste
Management
Evaluation Model
(IWEM) User's Guide
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Office of Solid Waste and Emergency Response (5305W)
Washington, DC 20460
EPA530-R-02-013
August 2002
www.epa.gov/osw
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EPA530-R-02-013
August 2002
Industrial Waste Management
Evaluation Model (IWEM)
User's Guide
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Office of Solid Waste and Emergency Response (5305W)
U.S. Environmental Protection Agency
1200 Pennsylvania Ave., N.W.
Washington, DC 20460
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IWEM User's Guide
ACKNOWLEDGMENTS
Numerous individuals have contributed to this work. Ms. Ann Johnson and Mr. David
Cozzie of the U.S. EPA, Office of Solid Waste (EPA/OSW) provided overall project
coordination, review, and guidance. Mr. Timothy Taylor (EPA/OSW) provided technical
guidance for the IWEM software development. Ms. Shen-Yi Yang and Mr. John Sager
(EPA/OSW) reviewed and coordinated the development of this document. This report
and the IWEM software were prepared by the staffs of Resource Management Concepts,
Inc. (RMC) and HydroGeoLogic, Inc. (HGL) under EPA Contract Number 68-W-01-004.
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IWEM User's Guide
FORMAT AND NOTATION
The main font for this document is 12-point Times New Roman font. The 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, IFlLEl and lEVALUATlONl 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 IFlLE|dPENl.
IWEM screen and dialog box titles are presented in underlined text; user-entry labels
are using the same format as IWEM menu items and other action-controls; and references
to user-supplied text are shown in 12-point Courier font. For example, the user could
provide Rodney' s Waste Dump as Facility Name in screen Tier 2 Input: WMU
Type (17).
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 Infiltration
(19) and Constituent List (20) 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 a Tier 1 or Tier 2
analysis and then move through the screens sequentially using the INEXTl and IBACKl
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
first-time IWEM Tier 1 user will see the following sequence screens:
• Introductory Screens (screens 1 through 5)
• Tier 1 Input screen group (tabbed screens 6 through 8)
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IWEM User's Guide
• Tier 1 Results screen group (tabbed screens 9 through 13)
• Tier 1 Evaluation Summary Screen (screen 14)
Similarly, a Tier 2 user will typically see the following sequence of screens and
dialog boxes (however, there are some slight differences in this sequence depending upon
the WMU type and infiltration option chosen by the user):
• Tier 2 input screen group (tabbed screens 16 through 23, including dialog box 19a
that is associated with tabbed screen 19 and dialog boxes 20a to 20d that are
associated with tabbed screen 20)
• EPACMTP Run Manager located on the Tier 2 Evaluation Screen (screen 24)
• Tier 2 Output tabs (tabbed screens 25 through 28)
• Tier 2 Evaluation Summary Screen (screen 29)
Please note that the screenshots presented in this User's Guide were captured using
the following settings to ensure maximum legibility:
• monitor set to 800 x 600 resolution
• large system font
• IWEM program window (parent window) maximized
• IWEM (tabbed) screen (child window) enlarged to its fullest extent
If you use other settings while running IWEM, 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.
in
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IWEM User's Guide Table of Contents
TABLE OF CONTENTS
Section Page
1.0 Introduction 1-1
1.1 Guide for Industrial Waste Management 1-1
1.2 The IWEM Software 1-2
1.3 Objectives 1-3
2.0 IWEM Overview 2-1
2.1 What does the software do? 2-1
2.1.1 Tier 1 Evaluation 2-2
2.1.2 Tier 2 Evaluation 2-3
2.1.3 Tier 3 Evaluation vs IWEM 2-4
2.2 IWEM Software Components 2-5
2.2.1 IWEM User Interface 2-5
2.2.2 EPACMTP Fate and Transport Model 2-6
2.2.2.1 IWEM vs. EPACMTP 2-9
2.2.3 IWEM Databases 2-10
2.3 Assumptions and Limitations of Ground-Water Modeling 2-10
3.0 System Requirements 3-1
4.0 IWEM Software Installation 4-1
5.0 Running the IWEM Software 5-1
5.1 How do I start the IWEM software? 5-1
5.2 What are the key features of the IWEM software? 5-1
5.2.1 What is the Constituent Properties Browser? 5-4
5.2.2 How Do I Navigate Through the IWEM Software? 5-8
5.2.2.1 Screens 5-9
5.2.2.2 Controls 5-9
5.2.3 How Do I Use Online Help? 5-16
5.2.4 How Do I Save My Work? 5-17
5.2.5 How Do I Get Help If I Have a Problem or a Question? 5-18
5.2.6 How Do I Begin Using the IWEM Software? 5-19
5.3 Introductory Screens (Screens 1 through 5) 5-19
5.4 Tier 1 Evaluation 5-28
5.4.1 Tier 1 Input Screen Group 5-28
5.4.1.1 Tier I Input: WMU Type (6) 5-28
5.4.1.2 Tier I Input: Constituent List (7) 5-30
5.4.1.3 Tier I Input: Leachate Concentration (8) 5-34
iv
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IWEM User's Guide Table of Contents
TABLE OF CONTENTS (continued)
Section Page
5.4.2 Tier I Output (Summary) Screen Group: MCL Summary
and HBN Summary (9 and 10) 5-36
5.4.3 Tier 1 Output (Details) Screen Group: Results - No Liner,
Single Clay Liner, and Composite Liner (11, 12, and 13) .... 5-40
5.4.4 Tier 1 Evaluation Summary Screen (14) 5-46
5.4.5 Exiting the IWEM software 5-49
5.5 Tier 2 Evaluation 5-50
5.5.1 Tier 2 Input Screens 5-51
5.5.1.1 Tier 2 Input: Waste Management Unit Type (16) . 5-51
5.5.1.2 Tier 2 Input: WMU Parameters (17) 5-53
5.5.1.3 Tier 2 Input: Subsurface Parameters (18) 5-59
5.5.1.4 Tier 2 Input: Infiltration (19) 5-63
5.5.1.5 Probabilistic Screening Module 5-73
5.5.1.6 Tier 2 Input: Constituent List (20) 5-75
5.5.1.7 Tier 2 Input: Constituent Properties (21) 5-84
5.5.1.8 Tier 2 Input: Reference Ground-Water
Concentrations (22) 5-87
5.5.1.9 Tier 2 Input: Input Summary (23) 5-89
5.5.2 Tier 2 Evaluation: Run Manager (24) 5-91
5.5.3 Tier 2 Evaluation Summary: Summary Results Screen
(Screen 25) 5-96
5.5.4 Tier 2 Output (Details) (26, 27, and 28) 5-99
5.5.5 Tier 2 Evaluation Summary (29) 5-104
6.0 Understanding Your IWEM Input Values 6-1
6.1 Parameters Common to Both Tier 1 and Tier 2 Evaluations 6-1
6.1.1 WMU Type 6-2
6.1.2 Waste Constituents 6-4
6.1.3 Leachate Concentration 6-4
6.1.4 Reference Ground-water Concentrations 6-4
6.1.4.1 Maximum Contaminant Level (MCL) 6-5
6.1.4.2 Health-Based Number (HBN) 6-5
6.1.4.3 Selection of the RGC within the IWEM Software . . 6-6
6.2 Additional Parameters for Tier 2 Evaluation 6-6
6.2.1 Basis for Using Site-Specific Parameter Values 6-6
6.2.2 Tier 2 Parameters 6-7
6.2.2.1 Tier 2 Parameters that Require User Inputs 6-7
6.2.2.2 Optional Tier 2 Parameters 6-7
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IWEM User's Guide Table of Contents
TABLE OF CONTENTS (continued)
Section Page
6.2.2.3 Default Values for Missing Data 6-10
6.2.2.4 How IWEM Handles Infeasible User
Input Parameters 6-10
6.2.3 Tier 2 Parameter Descriptions 6-10
6.2.3.1 WMU Parameters 6-11
6.2.3.2 Subsurface Parameters 6-15
6.2.3.3 Infiltration and Recharge Parameters 6-21
6.2.3.4 Constituent Parameters 6-25
7.0 Understanding Your IWEM Results 7-1
7.1 Leachate Concentration Threshold Values (LCTVs) 7-1
7.2 Limits on the LCTV 7-2
7.2.1 Toxicity Characteristic Rule (TC Rule) Regulatory Levels 7-2
7.2.2 1,000 mg/L Cap 7-2
7.2.3 Constituents with Toxic Daughter Products 7-3
7.3 IWEM Liner Recommendations 7-5
8.0 Trouble Shooting 8-1
9.0 References 9-1
Appendix A: List of Waste Constituents
Appendix B: Sample Reports from Tier 1 and Tier 2
VI
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IWEM User's Guide
Table of Contents
LIST OF FIGURES
Page
Figure 2.1 Sample IWEM Screen 2-6
Figure 2.2 Conceptual View of Aquifer System Modeled by EPACMTP 2-7
Figure 5.1 General IWEM Screen Features 5-2
Figure 5.2 Constituent Properties Browser 5-5
Figure 5.3 Constituent Properties Browser Full Source Dialog Box 5-7
Figure 5.4 Example IWEM Screen Identifying Several Types of Controls 5-10
Figure 5.5 Example IWEM Screen Identifying Several Types of Controls 5-11
Figure 5.6 Example IWEM Screen Identifying Several Types of Controls 5-14
Figure 5.7 Example IWEM Screen Identifying Several Types of Controls 5-15
Figure 5.8 IWEM Online Help 5-16
Figure 5.9 Introduction: IWEM Overview (1) 5-21
Figure 5.10 Introduction: Use of IWEM (2) 5-22
Figure 5.11 Introduction: Data Requirements (3) 5-23
Figure 5.12 Introduction: Model Limitations (4) 5-24
Figure 5.13 Introduction: Choose Evaluation Type (5) 5-25
Figure 5.14 Tier 1 Input: WMU Type (6) 5-29
Figure 5.15 Tier 1 Input: Constituent List (7) 5-31
Figure 5.16 Tier 1 Input: Leachate Concentration (8) 5-34
Figure 5.17 Tier 1 Output (Summary): MCL Summary (9) 5-37
Figure 5.18 Tier 1 Output (Summary): HBN Summary (10) 5-38
Figure 5.19 Tier 1 Output (Details): Results - No Liner (11) 5-41
Figure 5.20 Tier 1 Output (Details): Results - Single Clay Liner (12) 5-42
Figure 5.21 Tier 1 Output (Details): Results - Composite Liner (13) 5-43
Figure 5.22 Tier 1 Evaluation Summary (14) 5-46
Figure 5.23 Tier 2 Input: WMU Type (16) 5-52
Figure 5.24 Tier 2 Input: WMU Parameters (17) for Land Application Units ... 5-54
Figure 5.25 Tier 2 Input: WMU Parameters (17) for Landfills 5-55
Figure 5.26 Tier 2 Input: WMU Parameters (17) for Surface Impoundments .... 5-56
Figure 5.27 Tier 2 Input: WMU Parameters (17) for Waste Piles 5-57
Figure 5.28 Tier 2 Input: Subsurface Parameters (18) - Selecting Subsurface
Environment 5-60
Figure 5.29 Tier 2 Input: Subsurface Parameters (18) - Entering Values
of Subsurface Parameters 5-61
Figure 5.30 Tier 2 Input: Infiltration (19) - Initial Appearance 5-64
Figure 5.31 Tier 2 Input: Infiltration (19) - Land Application Unit 5-65
Figure 5.32 Tier 2 Input: Infiltration (19) - Landfill 5-66
Figure 5.33 Tier 2 Input: Infiltration (19) - Surface Impoundment 5-67
Figure 5.34 Tier 2 Input: Infiltration (19) - Waste Pile 5-68
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IWEM User's Guide
Table of Contents
LIST OF FIGURES (continued)
Page
Figure 5.35 Tier 2 Input: Climate Center List (19a) 5-71
Figure 5.36 Tier 2 Input: Infiltration (19) - Site Specific Infiltration 5-73
Figure 5.37 Tier 2 Input: Constituent List (20) 5-76
Figure 5.38 Tier 2 Input: Enter New Constituent Data (20a) 5-80
Figure 5.39 Tier 2 Input: New Constituent Data (20b) 5-81
Figure 5.40 Tier 2 Input: Add New Data Source (20d) 5-83
Figure 5.41 Tier 2 Input: Constituent Properties (21) 5-85
Figure 5.42 Tier 2 Input: Reference Ground-Water Concentrations (22) 5-88
Figure 5.43 Tier 2 Input: Input Summary (23) 5-90
Figure 5.44 Tier 2 Evaluation: Run Manager (24) - Appearance Before Launching
EPACMTP Runs 5-92
Figure 5.45 Tier 2 Evaluation: Run Manager (24) - EPACMTP Dialog Box
Displayed During Model Execution 5-94
Figure 5.46 Tier 2 Evaluation: Run Manager (24) - Status and Liner
Protectiveness Summary 5-95
Figure 5.47 Tier 2 Output (Summary): Summary Results (25) 5-97
Figure 5.48 Tier 2 Output (Details): Results-No Liner (26) 5-100
Figure 5.49 Tier 2 Output (Details): Results-Single Liner (27) 5-101
Figure 5.50 Tier 2 Output (Details): Results-Composite Liner (28) 5-102
Figure 5.51 Tier 2 Evaluation Summary (29) 5-105
Figure 6.1 WMU Types Modeled in IWEM 6-3
Figure 6.2 WMU with Base Below Ground Surface 6-12
Figure 6.3 Position of the Modeled Well Relative to the Waste
Management Unit 6-14
Figure 6.4 Locations of IWEM Climate Stations 6-24
Vlll
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IWEM User's Guide Table of Contents
LIST OF TABLES
Page
Table 2.1 IWEM WMU and Liner Combinations 2-2
Table 6.1 Tier 2 Parameters 6-8
Table 7.1 Toxicity Characteristic Leachate Levels 7-3
IX
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IWEM User's Guide
CAS Number
cm/sec
CSF
DAF
EPA
EPACMTP
GUI
Guide
HBN
HELP
HQ
IWEM
kd
Koc
LAU
LCTV
LF
MB
MCL
MCLG
mg/L
MINTEQA2
MS
NPDWR
OSW
ACRONYMS AND ABBREVIATIONS
Chemical Abstract Service Registry Number
centimeters per second
Cancer Slope Factor
Dilution and Attenuation Factor
Environmental Protection Agency
EPA's Composite Model for Leachate Migration with
Transformation Products
Graphical User Interface
Guide for Industrial Waste Management
Health-Based Number
Hydrologic Evaluation of Landfill Performance
Hazard Quotient
Industrial Waste Management Evaluation Model
Soil - Water Partition Coefficient
Organic Carbon Partition Coefficient
Land Application Unit (also called a Land Treatment Unit)
Leachate Concentration Threshold Value
Landfill
megabyte
Maximum Contaminant Level
Maximum Contaminant Level Goal
milligrams per liter
EPA's geochemical equilibrium speciation model for dilute
aqueous systems
Microsoft™
National Primary Drinking Water Regulation
EPA's Office of Solid Waste
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IWEM User's Guide
ACRONYMS AND ABBREVIATIONS (continued)
RAM Random Access Memory
RCRA Resource Conservation and Recovery Act
RGC Reference Ground-Water Concentration
SI Surface Impoundment
SPLP Synthetic Precipitation Leaching Procedure
STORET EPA's Data Storage and Retrieval System, National Water Quality
Database
TC Rule Toxicity Characteristic Rule
TCLP Toxicity Characteristic Leaching Procedure
U.S. EPA United States Environmental Protection Agency
WMU Waste Management Unit
WP Waste Pile
XI
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IWEM User's Guide Section 1.0
1.0 Introduction
This document describes how to use the Industrial Waste Management Evaluation
Model (IWEM). IWEM is the ground-water modeling component of the Guide for
Industrial Waste Management (Guide) (U.S. EPA, 2002d), which has been developed by
the U.S. Environmental Protection Agency's (EPA's) Office of Solid Waste (OSW) for
the management of non-hazardous industrial wastes. A companion document, the
Industrial Waste Management Evaluation Model Technical Background Document (U.S.
EPA, 2002c), provides technical background information. It is strongly recommended
that you take the time to understand the technical background of IWEM in order to make
the best use of this program. This section of the User's Guide provides an overview of
IWEM and its purpose, operation, and application; describes the major components of the
system; and provides an overview of how the remainder of the document is organized.
1.1 Guide for Industrial Waste Management
The EPA and representatives from 12 state environmental agencies have
developed a voluntary Guide (U.S. EPA, 2002d) to recommend a baseline of protective
design and operating practices to manage nonhazardous industrial wastes throughout the
country. The guidance was designed for facility managers, regulatory agency staff, and
the public, and it reflects four underlying objectives:
• Adopt a multimedia approach to protect human health and the
environment;
• Tailor management practices to risk using the innovative, user-friendly
modeling software provided in the Guide;
• Affirm state and tribal leadership in ensuring protective industrial waste
management, and use the Guide to complement state and tribal programs;
and
• Foster partnerships among facility managers, the public, and regulatory
agencies.
The Guide recommends best management practices and key factors to consider to
protect ground water, surface water, and ambient air quality in siting, designing and
operating waste management units (WMUs); monitoring WMUs' impact on the
environment; determining necessary corrective action; closing WMUs; and providing
post-closure care. In particular, the guidance recommends risk-based approaches to
choosing liner systems and waste application rates for ground-water protection and to
TT
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IWEM User's Guide Section 1.0
evaluate the need for air controls. The CD-ROM version of the Guide includes user-
friendly air and ground-water models to conduct these risk evaluations. The IWEM
software described in this User's Guide is the ground-water model that was developed to
support the Guide.
1.2 The IWEM Software
The IWEM software is designed to assist you in determining the most appropriate
WMU design to minimize or avoid adverse ground-water impacts, by evaluating types of
liners, the hydrogeologic conditions of the site, and the toxicity and expected leachate
concentrations of the anticipated waste constituents. That is, this software helps you
compare the ground-water protection afforded by various liner systems with the
anticipated waste leachate concentrations, so that you can determine what minimum liner
system is needed to be protective of human health and ground-water resources (or in the
case of land application units (LAUs), determine whether or not land application is
recommended).
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.
• State regulators may wish to use the software in developing permit
conditions for a WMU.
• Interested members of the public or community groups may wish to
use the software to evaluate a particular WMU and participate during the
permitting process.
In an effort to meet the needs of various stakeholders, the guidance for the
ground-water pathway uses a tiered approach that is based on modeling the fate and
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IWEM User's Guide Section 1.0
transport of waste constituents through subsurface soils and ground water to a well1 to
produce a liner recommendation (or a recommendation concerning land application) that
protects human health and the environment. The successive tiers in the analysis
incorporate increasing amount of site-specific data to tailor protective management
practices to the particular circumstances at the modeled site:
• Tier 1: A screening analysis based upon national distributions of data;
• Tier 2: A location-adjusted analysis using a limited set of the most
sensitive waste- and site-specific data; and
• Tier 3: A comprehensive and detailed site assessment.
The IWEM software is designed to support the Tier 1 and Tier 2 analyses. The
unique aspect of the IWEM software is that it allows the user to perform Tier 1 and Tier 2
analyses and obtain liner recommendations with minimal data requirements. Users
interested in a Tier 3 analysis should consult the Guide for information regarding the
selection of an appropriate ground-water fate and transport model.
1.3 Objectives
The objective of this User's Guide is to provide the information necessary to
perform Tier 1 and Tier 2 analyses for four types of WMUs:
• Landfills (LFs);
• Waste Piles (WPs);
• Surface Impoundments (Sis); and
• Land Application Units (LAUs) (which are also called Land Treatment
Units).
This User's Guide is organized as follows:
• Section 2 provides an overview of the IWEM software;
• Section 3 summarizes the computer system requirements for the IWEM
software;
• Section 4 provides instructions for installing the IWEM software;
• Section 5 provides detailed instructions on how to run the IWEM software,
and guides you step-by-step through Tier 1 and Tier 2 evaluations;
In IWEM, the term "well" is used to represent an actual or hypothetical ground-water monitoring
well or drinking water well, downgradient from a WMU.
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IWEM User's Guide Section 1.0
• Section 6 presents background information to assist in understanding the Tier
1 and Tier 2 input values; how they affect the model evaluation; and how to
obtain input values for a Tier 2 evaluation;
• Section 7 presents background information to assist in understanding the Tier
1 and Tier 2 IWEM results;
• Section 8 provides troubleshooting information for some commonly
encountered problems;
• Section 9 lists all references cited;
• Appendix A presents the list of waste constituents included in IWEM; and
• Appendix B presents the Tier 1 and Tier 2 reports for the example evaluations
presented in this document.
If you have a copy of the CD, you can open and read this User's Guide 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.
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IWEM User's Guide Section 2.0
2.0 IWEM Overview
The IWEM software developed by the EPA provides a two-tiered analysis that
requires a minimum of data. The analysis produces recommendations for the type of liner
to be used in a WMU and/or whether land application is appropriate. The two-tiered
analysis is presented within a user-friendly, Windows-based program called IWEM.
IWEM will operate on any standard personal computer using Windows™ 95 or later
operating system (see Section 3.0 for system requirements). A brief overview of IWEM
is provided in the remainder of Section 2.0.
2.1 What does the software do?
The IWEM software is designed to assist you in determining a recommended liner
design for different types of Resource Conservation and Recovery Act (RCRA) Subtitle
D (non-hazardous) WMUs. IWEM compares the expected leachate concentration2
entered by the user for each waste constituent with the leachate concentration threshold
value (LCTVs)3 calculated by a ground-water fate and transport model for three standard
liner types4.
The IWEM software compiles the results for all constituents expected in the
leachate and then reports the minimum liner scenario that is protective for all
constituents. Table 2.1 shows the combinations of WMUs and liners that are represented
in IWEM. For LAUs, only the no-liner scenario is evaluated because liners are not
typically used at this type of facility.
The IWEM software supports file saving and retrieval so that evaluations can be
archived or retrieved later and modified. The software also has report generation
capabilities to document in hard-copy the input values and resulting liner
recommendations.
The expected 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. Typically this concentration is measured using a laboratory leachate test. Chapter 2 (Characterizing
Waste) of the Guide provides more information on selecting a leachate test.
The LCTV represents the maximum allowable leachate concentration that is protective of ground
water; if the expected leachate concentrations of all constituents are less than their LCTVs for a particular
waste management scenario, then we recommend you select that WMU design to manage that particular
waste.
The three liner designs in IWEM are: no liner, single clay liner, and composite liner (see Table
2.1).
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IWEM User's Guide
Section 2.0
Table 2.1 IWEM WMU and Liner Combinations
WMU Type
Landfill
Surface Impoundment
Waste Pile
Land Application Unit
Liner Type
No Liner (in-situ soil)
•
•
•
•
Single Clay
Liner
•
•
•
N/A
Composite Liner
•
•
•
N/A
N/A = Not applicable
2.1.1 Tier 1 Evaluation
In a Tier 1 evaluation, the required inputs are the WMU type you wish to evaluate,
constituents of concern, and the expected leachate concentration for each constituent of
concern. After providing these inputs, IWEM determines a minimum recommended liner
design that is protective for all waste constituents. This determination is made by
comparing the expected leachate concentration for each constituent to tabulated values of
liner- and constituent-specific LCTVs, and identifying for which liner designs the LCTV
of each constituent is equal to, or greater than the input value of expected leachate
concentration. IWEM incorporates LCTV values for 206 organic and 20 metal
constituents (see Appendix A) that are part of the software's built-in database. These
LCTVs were generated by
running EPA's Composite
Model for Leachate Migration
with Transformation Products
(EPACMTP, described in
Section 2.2.2 below) for a wide
range of site conditions
expected to occur at waste sites
across the United States.
The process used to
simulate varying site conditions
is known as Monte Carlo
analysis. The Monte Carlo
analysis determines the
statistical probability that the
release of leachate would result
in a ground-water
About Monte Carlo Analysis:
Monte Carlo analysis is a computer-based method of analysis
developed in the 1940's 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).
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IWEM User's Guide Section 2.0
concentration exceeding regulatory or risk-based standards. The Tier 1 LCTVs, are
designed to be protective with 90% certainty for possible waste sites in the United States.
The advantages of a Tier 1 evaluation are that it is fast and does not require site-
specific information. Tier 1 is designed to be a screening analysis that is protective for
most sites. This means that a Tier 1 analysis may result in a liner recommendation that is
more stringent - - and costly to implement - - than is needed for a particular site. For
instance, site-specific conditions such as low precipitation and a deep unsaturated zone
may warrant a less stringent liner design.
2.1.2 Tier 2 Evaluation
A Tier 2 evaluation utilizes information on the unit's location and other site-
specific data enabling you to perform a more precise assessment. 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.
To perform Tier 2 evaluations, IWEM runs a complete EPACMTP fate and
transport simulation using site-specific input data, and generates a probability distribution
of expected ground-water well concentrations for each waste constituent and liner
scenario. It then compares the 90th percentile of the modeled ground-water well
concentration to a reference ground-water concentration (RGC5) value (for instance, a
regulatory maximum contaminant level (MCL)) until it has identified the liner design for
which the 90th percentile of the expected ground-water concentration does not exceed the
RGC.
IWEM is designed to allow Tier 2 evaluations with varying levels of available
site-specific information and data. 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
have available. 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.
5 See Section 6.1.4 (page 6-4) for a definition of RGC.
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Section 2.0
Tier 2 users can perform an evaluation for any of the waste constituents that are
included in Tier 1; Tier 2 users also have the option to include additional waste
constituent(s) and/or modify constituent properties in the default database. Specifically,
you can provide constituent-specific soil - water partition coefficient (kd) and degradation
(A) coefficients, and a user-defined RGC and exposure duration.
In many cases, a Tier 2 evaluation will allow a less stringent and less costly liner
design than the Tier 1 screening analysis will allow. If a site is vulnerable to ground-
water contamination, a Tier 2 analysis will allow you to determine appropriate waste
management options and liner designs with greater confidence than a Tier 1 analysis.
Chapter 4 of the Guide discusses siting considerations for WMUs, including how to
recognize a vulnerable hydrogeological setting. The trade-off in performing a Tier 2
evaluation is that the fate and transport simulations are computationally demanding and
can take hours to complete, even with a very fast personal computer. The reason is that
the Tier 2 model simulations incorporate Monte Carlo analysis to handle the uncertainty
associated with default values and other modeling parameters that are not user-specified.
2.1.3 Tier 3 Evaluation vs IWEM
If the IWEM Tier 1 and Tier 2
evaluations do not adequately simulate
conditions at a proposed site because the
hydrogeology of the site is complex, you
may consider a comprehensive site-
specific risk assessment. For example, if
ground-water flow is subject to seasonal
variations, performing a Tier 2
Evaluation in IWEM may not be
appropriate because the model is based
on steady-state flow conditions. A
comprehensive site-specific ground-water
fate and transport analysis may be
required to evaluate risk to ground water
and alternative liner designs or land
application rates. 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
Why it is important to use a qualified
professional?
• 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
land application rate.
• 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 Section 2.0
for a good consultant to perform the analysis. For more details see Chapter 7A of the
Guide.
2.2 IWEM Software Components
The IWEM software consists of three main components (or modules): (z) a
Graphical User Interface (GUI) which guides you through a series of user-friendly screens
to perform Tier 1 and Tier 2 evaluations; (ii) the EPACMTP computational engine and
integrated Monte Carlo processor that perform the ground-water fate and transport
simulations for Tier 2 evaluations; and (Hi) a series of databases of waste constituents,
WMUs, and site-specific parameters. Each of these three components is discussed briefly
in this section.
2.2.1 IWEM User Interface
When you use the IWEM software, you are interacting with the GUI module.
This module consists of a series of data input and display screens, that enable you to
define a Tier 1 and/or a Tier 2 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 5 of this User's
Guide.
If you are performing a Tier 1 evaluation, the software simply performs a table
look-up of the Tier 1 LCTV tables that are built into the software for the WMU and waste
constituent(s) you selected. Once you have specified all the Tier 1 data inputs, the results
of the evaluation are instantaneously available for on-screen display or printing in a hard-
copy report.
If you are performing a Tier 2 evaluation, the GUI will take you through a step-
wise process of assembling the pertinent site-specific data. The GUI 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 EPACMTP model. Upon completion of the site-specific fate and
transport simulations, IWEM will display the liner recommendation and generate a
printed report if desired.
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IWEM User's Guide
Section 2.0
Menu Bar
Toolbar
Title Bar
file Evafc0on Options
Constituent Properties
Related
Constituents
Constituent Name
Leachate
Concanfration
(mg/L)
Toxidty
Standard
RGC
(mg/L)
LogfKoc)
(L/kg)
Ka
(/mol/yt)
Kn(/yr)
Kb
f/mol/yr)
Kd (L/kg)
QveraN Decay
Coefitient(/yr)
79-OFH Aaylamide
01 HBN- 220E-OS
Ingestion
Car;ce(
Depth ot base of the LF below ground surface
U depth (m) fsequites site specific value]
Depth to water table (m)
Soil type SILT LOAM
nfiltrafton
No Lmer DS6-1
Single Liner 0295
Composite Liner Monte Carlo
Recharge Rate 00564
Figure 2.1 Sample IWEM Screen.
2.2.2 EPACMTP Fate and Transport Model
EPACMTP is a sophisticated fate and transport model that simulates the
migration of waste constituents in leachate from land disposal units through soil and
ground water. EPACMTP has been developed by EPA's OSW 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 the EPACMTP; a complete description of the
model is provided in the EPACMTP Technical Background Document (U.S. EPA,
2002a). The IWEM Technical Background Document (U.S. EPA, 2002c) describes how
we used EPACMTP to develop the Tier 1 and Tier 2 Evaluations in IWEM.
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IWEM User's Guide
Section 2.0
LEACHATE CONCENTRATION
UNSATURATED
ZONE
WASTE MANAGEMENT UNIT
SATURATED
ZONE
LAND SURFACE
WATER TABLE
LEACHATE PLUME.
Figure 2.2 Conceptual View of Aquifer System Modeled by EPACMTP.
EPACMTP simulates fate and transport of constituents in both the unsaturated
zone and the saturated zone. Figure 2.2 shows a conceptual, cross-sectional view of fate
and transport modeled by EPACMTP. The source of constituents is a WMU located at or
near the ground surface overlying an unconfined aquifer. Waste constituents leach from
the base of the WMU 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 2.2, EPACMTP accounts for the spreading of the
plume in all three dimensions.
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 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 WMU with a high
infiltration rate and its effect on ground-water flow. This may be significant, particularly
in the case of unlined Sis. 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 the WMU.
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
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IWEM User's Guide Section 2.0
as bio-chemical transformation (degradation) processes in the unsaturated and saturated
zone. These processes decrease constituent concentrations in the ground water as the
distance from the WMU increases.
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 sorption isotherms for a range of
aquifer geochemical conditions, as generated using the MINTEQA26 geochemical
speciation model.
In Tier 1 and as the default in Tier 2, EPACMTP only accounts for constituent
transformations caused by hydrolysis reactions. Hydrolysis refers to constituent
decomposition that results from chemical reactions with water. In Tier 2 analyses,
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 which hydrolyze into toxic daughter
products. In that case, the final liner recommendations are determined in such a way that
they accommodate both the parent constituent as well as 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 final liner recommendation would be
based on the exposure caused by the daughter product.
In Tier 2, IWEM makes liner recommendations by comparing ground-water
exposure concentration values predicted by EPACMTP against RGCs that are either
regulatory MCLs or cancer and non-cancer Health-Based Numbers (HBNs). For the
IWEM analysis, the ground-water exposure concentration is evaluated at a hypothetical
well that is located downgradient from the WMU. 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 the assumptions
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.
-------
IWEM User's Guide Section 2.0
incorporated in the RGC. For instance, when the ground-water exposure concentration is
compared to a RGC that is based on cancer risk, the averaging period is set to 30 years;
whereas for non-cancer effects caused by ingestion of water, EPA considered only
childhood exposure, and set the averaging period to 7 years (covering the time period
from birth through the 6th year of life).
In both Tier 1 and Tier 2 analyses, the groundwater modeling results of the
EPACMTP model are summarized by IWEM in terms of Dilution and Attenuation
Factors (DAFs). A DAF is a numerical value that represents the reduction in the
concentration of a constituent arriving at the modeled ground-water well as compared to
the concentration of that constituent in the waste leachate. A DAF value of 10 means that
the concentration at the well is 10 times less than the concentration in the leachate. Using
DAFs is a convenient way to go back-and forth between leachate concentrations and
exposure concentrations, or ground-water reference concentrations.
2.2.2.1 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 Tier 1 and/or Tier 2 analyses of the ground-water pathway within
the context of the EPA's Guide. Specifically, within Tier 1, IWEM can be used to query
a database of existing EPACMTP modeling results in the form of LCTV values, and to
analyze these tabulated results to produce a Tier 1 WMU design recommendation that is
specific to your waste. Within Tier 2, 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 Tier 2 WMU design recommendation that is specific
to your waste and your waste site. In addition, for both tiers of analysis the IWEM
software has the capability to print and save document-ready reports that include the liner
recommendations and the input data on which they are based.
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 Tier 1
and Tier 2 analyses, not all of the EPACMTP functionality is available to the IWEM user;
however, the IWEM provides added capabilities to interpret results and develop reports,
which are not available within EPACMTP.
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IWEM User's Guide Section 2.0
2.2.3 IWEM Databases
The third 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 organics and 20 metals. 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, as well as RGCs. These RGC's
include: 1) regulatory MCLs, and 2) cancer and non-cancer HBNs for drinking water
ingestion and inhalation of volatiles during showering. Section 7 of this User's Guide
discusses how IWEM uses these RGC's to calculate LCTVs.
In addition to constituent data, IWEM includes a comprehensive database of
ground-water modeling data, including infiltration rates for different WMU types and
liner designs 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, 2002b), and in the IWEM Technical
Background Document (U.S. EPA, 2002c).
EPA used these databases to develop the IWEM Tier 1 LCTVs, and they are
incorporated into the IWEM software to perform Tier 2 evaluations. When site-specific
data are available for a Tier 2 evaluation, they will override default database values.
Conversely, when site-specific data are not available for a Tier 2 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
The tiered approach developed to evaluate WMU designs uses sophisticated
probabilistic techniques to account for uncertainty and parameter variability. To perform
the evaluations recommended by the Guide, the mathematical models represent
conditions that may potentially be encountered at waste management sites 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. 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, 2002c)
provides additional information to assist you in this process.
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IWEM User's Guide Section 2.0
EPACMTP represents WMU's 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 WMU and assumes that the only mechanism of constituent release is through
dissolution of waste constituents in the water that percolates through the WMU.
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 WMU via other environmental
pathways, such volatilization or surface run-off. EPACMTP assumes that the rate of
infiltration through the WMU 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.
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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 in Tier 2.
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 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 Tier 2 evaluations. 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.
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Section 3.0
3.0 System Requirements
The IWEM software is designed to run under the Microsoft (MS) Windows
operating system. Version 1.0 of IWEM has been designed and tested to run on the latest
versions of Windows 95, 98, NT version 4.0, 2000, and XP. In addition, in order to
ensure that all the files required to run IWEM are present on your computer, the latest
version of MS Internet Explorer that is compatible with your operating system needs to be
installed. Details are given in the table below:
Latest versions of MS Windows operating systems
95 (Version 4.00.950B)
98 Second Edition (Version 4.10.2222A)
NT 4.0 (Service Pack 6a)
2000 (Service Pack 2)
XP (Version 2002)
Corresponding version of MS
Internet Explorer
Version 5.5 Service Pack 2
Version 6.0
Version 6.0
Version 6.0
Version 6.0
If you do not have the latest version of your particular operating system, you may
encounter IWEM installation or execution problems (see Section 8.0). To avoid these
problems, make sure that you have the latest version MS Windows and Internet Explorer
installed on your computer before installing the IWEM software. To check the version
number of the operating system installed on your computer, right-click on the I MY
GovPUTERl icon on your desktop. Then choose I PROPERTIES! from the displayed list. The
ISYSTEM PROPERTIES! dialog box is then displayed, and the IGENERAL! screen is displayed by
default. The operating system name and version number are displayed under the ISYSTEM
heading.
If you find that you do not have the latest version of your particular operating
system, consult with your computer system administrator, or you may download the
updated version for free from the following website:
http://www.microsoft.com
From the main menu, click on |DCWNLQADS|WNDCWS UPDATE]. Then click on the link for
PRODUCT UPDATES|. The first time you do this, you will be asked to install the Windows
Update Control Package. Doing so will enable the automatic creation of a list of
available updates that is customized for your computer and operating system. Then
install the recommended updates to ensure that you are running the latest version of your
operating system.
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IWEM User's Guide Section 3.0
To check the version of MS Internet Explorer that is installed on your computer,
double-click on the I INTERNET EXPLORER! icon on your desktop. From the main menu, choose
hELP ABOUT INTERNET EXPLORER). The version number is displayed beneath the MS Internet
Explorer banner; make sure that the version number is at least 5.50.xxxx.xxxx if you are
running Windows 95 or is at least 6.00.xxxx.xxxx if you are running Windows 98 or
later. Only the first few digits of the Internet Explorer version number are important to
ensure correct operation of the IWEM software.
If you find that you do not have the latest version of MS Internet Explorer, you
may download the updated version for free from the following website:
http://www.microsoft.com
From the main menu, click on |DCWNLQADS|WNDOV\S UPDATE|. Then click on the link for
PRODUCT UPDATES! . The first time you do this, you will be asked to install the Windows
Update Control Package. Doing so will enable the automatic creation of a list of
available updates that is customized for your computer and operating system. If you do
not have the latest version of MS Internet Explorer, then this program will be included in
the list of recommended updates. In that case, download and install the recommended
file(s) in order to ensure that IWEM will operate correctly.
Your computer must meet the minimum hardware requirements for the version of
Windows that is installed on your computer. In addition, it is recommended that the
computer have at least 128 megabytes (MB) of RAM and 100 MB or more of available
hard-drive space. A printer is required for printing hard-copy reports.
To check your computer's random access memory (RAM), right-click on the IIW
GoiVPUTERl icon on your desktop. Then choose I PROPERTIES! from the displayed list. The
ISYSTEM PROPERTIES! dialog box is then displayed, and the IGENERAL! screen is displayed by
default. The amount of RAM is displayed as the last item under the IGoiVPUTERl heading.
To check your computer's available hard-drive space, double-click on the I MY GoiVPUTERl
icon on your desktop. Then choose |VIEW]DETAILS] from the main menu. The I MY GoiVPUTERl
dialog box is then displayed where you can check the amount of free space on your hard-
drive.
Running Tier 2 evaluations is computationally demanding. A fast computer
processor (e.g., at least a 500 MHz Pentium IE) is strongly recommended. Even
so, you should expect that Tier 2 analyses for multiple waste constituents may take
several hours to complete. A screen will be displayed during your Tier 2
evaluation to keep you informed about the progress of the computations.
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IWEM User's Guide Section 4.0
4.0 IWEM Software Installation
To use the IWEM software for the first time, you must install the software on your
hard-drive from the Guide CD-ROM, or download it from the EPA's non-hazardous
industrial waste website (http://www.epa.gov/industrialwaste/). Depending on the
security settings of your operating system, if your computer is connected to a network, or
if your computer uses the Windows NT, 2000, or XP operating systems, this software
may need to be installed and uninstalled by someone with administrator privileges.
Instructions for installing and uninstalling the program are provided below. Any updates
to these instructions are located in the Readme.txt file on the Guide CD-ROM and 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 5.2.5.
Installation from the Guide CD-ROM
1. Close all applications, such as word processing and e-mail programs. Close or
disable virus protection software.
2. If you have previously installed the Guide on your computer, then insert the
Guide CD into your CD-ROM drive. Depending upon your computer settings,
the Guide CD may automatically be launched.
If not, double-click on IMYGoiVPUTERl, double-click on your CD-ROM drive, and
then double-click on ISTART.EXEl
OR
Select |START|RUN| and type "D : \START . EXE," replacing the "D :" in this command
with the correct drive designation for your CD-ROM, as appropriate.
3. After following the prompts to log onto the Guide CD, use the command buttons
within the interactive Guide CD to navigate to the Industrial Waste Management
Main Menu. From there, select the Protecting Ground Water section, and then
select the Assessing Risk to Ground Water subsection.
4. Click the INEXT| button to display the Assessing Risk to Ground Water Topic Menu,
and then click on the following sequence of command buttons:
ITOOLS AND RESOURCES!
ITOOLS!
I INFO! for the IWEM model
I LAUNCH|
44
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IWEM User's Guide Section 4.0
llNSTALLNO/Vl
5. The IWEM Welcome screen then appears. If all your other applications are
already closed (Step 1), click INDCTl. If not, press the ITABl key while the lALTl key is
depressed to scroll through your open applications, closing each in turn.
6. The next screen is titled Choose Destination Location. This screen displays the
default installation location for the IWEM files. If you want to change the
location, click the IBROASEl button and specify a different directory. Click the INDCTl
button to proceed with the IWEM installation process.
7. The next screen is titled Select Program Manager Group. The default setting is to
create a new program group named "IWEM;" however, if desired, you can instead
choose one of the existing program groups from the list below or replace "IWEM"
with a name that you type in. Then click the INDCTl button to proceed with the
IWEM installation process.
8. The next screen is titled Start Installation. If you are happy with your selections
up to this point, click the INDCTl button to install the IWEM software to your hard-
drive. Otherwise, click the IBACKl button to change your installation settings.
9. The next screen is titled Installing. The Current File and All Files progress bars
are automatically updated as files are copied to your hard drive, and an estimate of
the time required to finish the installation is displayed on-screen.
10. As the installation process is finishing, a message box will be displayed that says
"Updating System Configuration, please wait..."
11. If you do not encounter any installation problems, the Installation Complete
screen will display the message, "IWEM has been successfully installed." In this
case, all you need to do is click on the IFlNlSHl button to complete the installation.
However, if you do experience installation problems, please see your computer
system administrator for help, or contact the RCRA Information Center as
explained in Section 5.2.5.
Installation from the EPA's non-hazardous industrial waste website
1. Close all applications, such as word processing and e-mail programs. Close or
disable virus protection software.
2. Open your internet browser and type in the following website:
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IWEM User's Guide Section 4.0
http://www.epa.gov/industrialwaste/
3. From the bulleted list, double-click on the link for the Guide.
4. Scroll down to the bottom of the page and click on the link for the IWEM.
5. Scroll down the page and click on the Download Model link.
6. The File Download dialog box will then appear. Choose the option to save the
program to disk and click the ION button to download this IWEM setup file to
your hard-drive.
7. The Save As dialog box will then appear. Navigate to the folder where you would
like the file to be saved and then click the ISAVEl button. The progress bar is
automatically updated as the IWEM setup file (IWEMSetup.exe) is downloaded to
your hard drive.
8. At the bottom of the Save As dialog box is a checkbox to specify if you want the
dialog box to close automatically when the download is complete. If you leave
the checkbox empty, then click on the lOPENl button when the download is
complete. If you have the checkbox selected, the dialog box will close upon
completion of the download. In this case, open IIWCoMPUTERl, browse to the folder
location where you saved the IWEM setup file, and double-click on the icon for
I I\AEMSERJP.EXE!
OR
Select ISfARTlRUNl, and either browse to the folder location where you saved the
IWEM setup file or type this folder location directly into the textbox. Then click
on the I OKI button.
9. The IWEM Welcome screen then appears. If all your other applications are
already closed (Step 1), click I NEXTl. If not, press the ITABl key while the lALTl key is
depressed to scroll through your open applications, closing each in turn.
10. The next screen is titled Choose Destination Location. This screen displays the
default installation location for the IWEM files. If you want to change the
location, click the IBROASEl button and specify a different directory. Click the INDCTl
button to proceed with the IWEM installation process.
11. The next screen is titled Select Program Manager Group. The default setting is to
create a new program group named "IWEM;" however, if desired, you can instead
-------
IWEM User's Guide Section 4.0
choose one of the existing program groups from the list below or replace "IWEM"
with a name that you type in. Then click the INEXTl button to proceed with the
IWEM installation process.
12. The next screen is titled Start Installation. If you are happy with your selections
up to this point, click the INEXTl button to install the IWEM software to your hard-
drive. Otherwise, click the IBACKl button to change your installation settings.
13. The next screen is titled Installing. The Current File and All Files progress bars
are automatically updated as files are copied to your hard drive, and an estimate of
the time required to finish the installation is displayed on-screen.
14. As the installation process is finishing, a message box will be displayed that says
"Updating System Configuration, please wait..."
15. If you do not encounter any installation problems, the Installation Complete
screen will display the message, "IWEM has been successfully installed." In this
case, all you need to do is click on the IFlNlSHl button to complete the installation.
However, if you do experience installation problems, please see your computer
system administrator for help, or contact the RCRA Information Center as
explained in Section 5.2.5.
Uninstalling
1. Click on the Microsoft Windows ISTARTI button in the extreme lower left corner of
your screen.
2. Select ISETTiNGSl, and then IGoNTTOL PANEL!.
3. Double-click on IADD/REMOVE PROGRAMS!.
4. Select I IWEM and then click on the ICHANGE/REMOVEl button.
5. The IWEM Select Uninstall Method screen is now displayed. You can choose
either an automatic or a custom uninstall process. The automatic process removes
only the IWEM files that were copied to your computer during IWEM installation;
that is, files of saved IWEM analyses are not deleted if you choose the automatic
uninstallation process. The custom uninstallation process allows you to specify
exactly which files you want to delete. Clicking on the ISELECTALLl button each
time it appears in the custom process can be used to delete every file that is
associated with the IWEM application, including shared files and saved IWEM
analyses.
-------
IWEM User's Guide Section 4.0
6. The IWEM Perform Uninstall screen then appears. If you are happy with your
selections up to this point, click the IFlNlSHl button to uninstall the IWEM software
from your hard-drive. Otherwise, click the IBACKl button to change your
uninstallation settings.
7. If the IWEM uninstall program finds that any of the files to be deleted is a shared
file that is no longer used by any programs, a message box titled Remove Shared
Component then appears. The filename will be displayed and you will be asked if
you want to delete this file. If any programs are still using this file and it is
removed, then those programs may not function correctly. Leaving the file on
your computer will not harm your system, but it does take up space on your hard-
drive. If you are unsure what to do, then you should select the I No TO ALLl button.
8. If you do not encounter any uninstallation problems, the IWEM program will then
be removed from the list of programs on the Add/Remove Programs dialog box.
However, if you do experience uninstallation problems, please see your computer
system administrator for help, or contact the RCRA Information Center as
explained in Section 5.2.5.
4-5
-------
IWEM User's Guide
Section 5.0
5.0 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 Tier 1 and Tier 2 evaluations.
5.1 How do I start the IWEM software?
To use the program for the first time, you can install the software from the Guide
CD (or download it from EPA's website: http://www.epa.gov/industrialwaste) to your
hard-drive. Section 4 gives detailed installation instructions.
Industrial Waste Management
Evaluation Model
IWEM
Version 1.0
Initializing...
U.S. Environmental
Protection Agency Office
of Solid Waste
After installation, you can launch the program by choosing START | PROGRAMS (at
the lower left corner of the screen) and then choosing | I\AEM| program group and the
program | I\AEM|. Alternatively, you can create a short-cut to the I\AEM program and
move it to your Windows desktop. In this case, the program can be launched by double-
clicking the | IWEM icon
on your desktop.
5.2 What are the key features of the IWEM software?
The IWEM software has a user-friendly interface which is designed to operate in
accordance with MS Windows™ conventions. The first screen that you see after
5-1
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IWEM User's Guide
Section 5.0
launching the program is the Start-Up screen (shown above) which will appear only while
the program is loading.
The first time you run the IWEM software, it displays five Introduction screens.
After reading them once, you can skip these screens in the future by un-checking the box
at the lower left of the introduction screens (see Section 5.3).
Menu
Bar
Toolbar
Title Bar
Input Summary (23)
Constituent Properties
Related
Constituents
Constituent Name
Leacnate
Concentration
(mg/L)
TcKicity
Standard
PGC
(mg/L)
Log(Koc)
(/mol/yr)
K.fl(7yr)
Kb
(/mol/yr)
Kd (L/kg)
Overall Decay
Coefficient (/yr)
79-06-1 Actylsmide
01 HBN- 220E-05
Ingestion
-0 989
315
0018 OOOEi-00
Area (
Depth ot base of the LF below ground surface (m)
epth (m) [requires site specific value]
Depth to water table (m)
Soil type SILT LOAM
nfiltration
No Lmet 0564
Single Liner 11295
Composite Liner. Monte Carlo
Recharge Rate 0 0561
13244 ^JAquifei thickness (m)
0 Regional hydraulic gradient
32 Aquiler hydraulic conductivity (m/yr)
(not specified) Distance to well (m)
(not specified) jJ
(not specified)
(not specified)
150
1J
Figure 5.1 General IWEM Screen Features.
5-2
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IWEM User's Guide
Section 5.0
As shown in Figure 5.1, the IWEM software interface follows a common layout
with the following features:
Menu Bar allows you to perform common file operations;
Toolbar also 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;
Name of Screen Group identifies the general topic addressed by the
individual screens that comprise this group (e.g., Tier 2 input screen group);
Screen Name more specifically identifies the type of information being
requested or displayed in the screen;
| PREVIOUS| button takes you to the previous screen; and
Ntxr| button allows you to proceed to the next screen.
From the menu bar, you can select among the following menu items:
• File: performs general file operations, such as open and save;
• Evaluation: proceeds directly to either the Tier 1 Evaluation or the Tier 2
Evaluation;
• Options: enables or suppresses toolbar visibility; and
• Help: provides access to the following information: search IWEM online
help; view IWEM introductory screens; browse constituent properties; view
contact information for IWEM technical support; and view the IWEM About
screen.
Using the toolbar is a quick way to perform common operations:
Clicking on this button begins a | NEW EVALUATION |
Clicking on this button launches the | OPEN RLE 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;
5-3
-------
IWEM User's Guide Section 5.0
II j Clicking on this button begins the TIER 1 EVALUATION |;
Clicking on this button begins the TIER 2 EVALUATION |; and
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.
In this section of the User's Guide, we present 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 a Tier 1 or Tier 2 analysis in
IWEM. The screenshots presented in Section 5 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 (A, B, C, etc) and are then listed and
explained sequentially in the text immediately following each screenshot.
5.2.1 What is the Constituent Properties Browser?
The Constituent Properties Browser, accessed from the Main Menu sequence
I-ELP 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 5.2). 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. RGC values,
cancer slope factors (CSFs), and non-cancer reference doses and reference concentrations
are given in the lower portion of the screen. For each property value in the database
(except constituent type, carcinogenicity, and molecular weight), the |DATASCURCE| field
provides access to a complete bibliographic citation (see Figure 5.3).
5-4
-------
IWEM User's Guide
Section 5.0
r-u
constituent
to view by
selecting
CAS
it
\ !fl Constituent Properties Brat iser
Select a constituent by CAS m
CAS Number;) 7440-36-0 «
•- Physical Properties
Paramtter
Carcinogen'
Molecular weight (q
•nberorname.
b 'jrj
?,
' J r*?1
and abbr
database
Constituent Name JAntmor
(Value
'mol)
No
Log KOC (distribution coefficient tor organic carbon) N/A
Ka. acid-catalyzed hydrolysis rote constant (1 /yr) N/A
K,n: neutral hydrolysis rate constant (1 ,'yr)
N/A
Kb base-catalyzed hydrolysis rate constant (1/yr) N/A
Solubility (mg/L)
Diffusivity in air (crn"
2/s)
4
eviat
ml
B. Ch
roperties cons(j
telXVEM sdect
r f v ,
y/
121 76
» looonoo
Dote
N/A
Caud
4
lose
uent
ng name
jjn].xl
t
Source
lidgeSoti Corporet on CHOI
N/A
L
-1
!
d
Reference Ground-water Concentration Values
Parameter
) Value
Maximum Contaminant Level
HBN - Ingestion. Cancer
Carcinogenic Slope Factor
- Oral
I Date Source
0.006
USEPA 2000h
N/A
N/A
HBN - Ingestion, Non-Cancer
04
To view a full source, click in the Data
Source cell, then click the "Full Source"
button, *
I CJt\
E, Close
Constituent
Properties
Browser
1098
USEPA3i01b
Jk
zJ
Eull Source
•
D. Reference ground-water R Click to view full
concentrations and J[)ATA SOURCE] of
abbreviated reference selected property
in the IWEM database
Figure 5.2 Constituent Properties Browser.
The features identified in Figure 5.2 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 —3 at the right edge of the CAS
NUMBER listbox to display a drop-down list of all available waste constituents. Then use
5-5
-------
IWEM User's Guide Section 5.0
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 ENTER | 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 NAIVE)
listbox on the right side of the screen. Click on the drop-down list control _LJ at the right
edge of the | CONSTITUENT NAIVE) listbox 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 ENTER) key to make your
selection.
C. Physical Properties and Abbreviated Reference in the IWEM Database
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. Reference Ground-water Concentrations and Abbreviated Reference in the IWEM
Database
For the selected waste constituent, the RGC input parameter values that are used
in the IWEM analysis and their corresponding data sources are listed in the lower table on
this screen.
E. Close Constituent Properties Browser
Click the OK) button at the bottom of the screen to close this screen.
5-6
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IWEM User's Guide
Section 5.0
F. Click to View Full | DATA SOURCE | of Selected Property
You can view the complete bibliographic citation of a constituent property by
selecting the corresponding entry under the | DATA SOURCE heading and clicking on the
| FULL SOURCE button on the lower right-hand side of the screen. Doing so will cause a
message box to appear on-screen, as is shown in Figure 5.3.
§ 'if- .-.,"• . -"•r ':";-:i:';->
ft, i -.•<:•"•'• • - - „' ... ;„; ^,
Select a constituent by CAS number or name
CAS Number. |?Wj-3b-0 Vj
- Physical Properties
Constituent Name: Antimony
Parameter
Value
| Data Source
Carcinogen' No
Molecular weight (g/mol)
Log KOC (distribution coefficient for organic carbon) N/A
Ka acid-catalyzed hydrolysis rate constant (1 /yr) N/A
Kn: neutral hydrolysis rate constant (1 /yr) N/A
Kb base-catalyzed hydrolysis rate constant (1/yr) N/A
Solubility (mg/L)
Diffusely in air(cmAZ
Reference Ground-wa
121 76 N/A
1000000 CambndgeSoft Corporation. 2001
J
Parameter
; Jl
CambrldgeSoft Corpocation, 2001. diemFhder.eom database arid Intsmet searthlng,
http://dMmnnder.CMnbridBHoFt.com. Aeetssed My 2001,
Maximum Contammai
HBN - Ingestion, Cam
Carcinogenic Slope F____
HBN - Ingestion, Non-Cancer
To view a full source, dick in the Data
Source cell, then click the "Full Source"
button.
00098 USEPA2001b
£ull Source
B. Click to close the
|FULL SOURCE|
dialoa box
A. Full |DATA SOURCE|
of selected property
Figure 5.3 Constituent Properties Browser Full Source Dialog Box.
5-7
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IWEM User's Guide Section 5.0
The features identified in Figure 5.3 are explained in more detail in the following
paragraphs.
A. Full | DATA SOURCE | of Selected Property
The bibliographic citation of the selected property is displayed in the FULL
SOURCE dialog box.
B. Click to Close the | FULL SOURCE Dialog Box
Click the OK| button to close the dialog box.
5.2.2 How Do I Navigate Through the IWEM Software?
The IWEM software is comprised 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 your 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 |ARRCW| keys, the |ALT| 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 "I" that indicates the position of the next typed character, or
the change in a control's appearance from normal to a highlighted appearance, as
presented below.
OK
OK
Normal Highlighted
When a control is highlighted, it is considered actively awaiting input from the
keyboard or mouse. The |BACK-TAB| key (press 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 |ARRCW-UP| or |ARROW-DCWN|
key to select a different radio button. The TAB| key moves you off the radio button group.
The |TAB|, |BACK-TAB|, and |ARRCW| keys 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-
5-8
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IWEM User's Guide Section 5.0
down list is active (highlighted), use the |ARROW-UP| or |ARRCW-DOV\M| 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 |Al_l| key and then pressing the |Q key
would have the same result as a mouse click on the button. Similarly, the main menu
system is activated by pressing the |Al_l| key; the first letter of each menu item is
underlined and can be accessed in the manner just described.
5.2.2.1 Screens
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 (see Figures 5.9 through 5.13) are examples of individual screens
that have PREVIOUS! and/or |NEXT| command buttons along the bottom for navigating from
screen to screen. The Tier 1 Input screen group (see Figure 5.14) consists of three screens
where you select a WMU type, identify the constituents in your waste, and enter your
leachate data. In addition to the navigational command buttons available on single
screens, you can also move to adjacent screens by clicking on their corresponding "tab".
5.2.2.2 Controls
The following controls make the IWEM software easy-to-use:
Text boxes;
Dialog boxes;
List boxes;
Radio Buttons;
Data grids;
Command buttons; and
Drop-down lists.
Each of these controls is explained in more detail in this section. 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 or the hot-key).
5-9
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IWEM User's Guide
Section 5.0
Text Boxes
Text boxes are used to display or accept information. The screen shown in Figure
5.4, text boxes (box B) 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. The screen shown in Figure 5.5 uses
text boxes to display data (box B) and to receive inputs (box E).
IS Tier 2 Input
Search By
instityent Nam
CAS NumbJr:
All Constituen s
Infiltrat an (19)
Constituent List (20)
Sort By
f* Constituent Name
(" CAS Number
j Constituent Prc 3erties (21)
Type of Constitut nt-
<• All constituents
r Organira
<~ Metals
83-32-9 Acer aphthene
75-07-0 Aceti ddehyde [Ethanal]
67-64-1 Acetane (2-propanone)
75-05-8 Acetanitrile (methyl cyanide)
98-86-2 AceWphenone
107-02-8 Acrolein
79-06-1 Acrylamide
79-1Q-7 Acrylic acid [propenoic acid]
107-13-1 Acrvionrtn e
309-00-2 Aldrm
107-18-6 Allyl alcohol
62-53-3 Aniline (benzeneemine)
Selected Constituents
CAS
Number
Constituent Name
Leachate
Concentration
(mg/g
107-13-1 Aoylonitrile
^dd New Con^uent
« Previous
Next»
D. ComniandJBuJ,ton
to move to previous
E. Command Buttons to
move items from list box
to data grid and vice
versa
F. Command Button
to start adding a
new constituent
G. Data Grid for
data display and
entry
H.
Button to
move to next
screen
Figure 5.4 Example IWEM Screen Identifying Several Types of Controls.
5-10
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IWEM User's Guide
Section 5.0
A. Data_Gridfor
display and selection
B. TextjBoxes for
data display
S>
41
>
'
'.'..
1 Constituent Propertes (21)
act a constituent from the grid, then the desired standard fror
Related Cons
Constituents
rtituent
Parent 107-13-1 Actylonitrile
Daughter 79-06-1 Aciylamide
Daughter 79-1 0-7 Acrylic acid [propenoic acid]
u
Standards for 79-10-7 Acrylic acid [pro|
Reference Ore
Select Standard Concentration
f
f
(!
f
<
HBN - Inhalation Non-Cancer 15 i
1 Reference GV
»the list. Click the1
ennii: acid]
und-water Ex
mg/L) Di
I 1
HBN - Ingestion, Non-Coneer 1 2
User-Defined •
\ Compare to all available standards |
lelect the desired standard by clicking its radio button Click the "Apply Sta
«Erevious
C. Ra Apply Standard(s) |
D. Command Button
for option
confirmation
Cone. (22) T
Input Summary (23)
1
1
^pply Standards" button to save each selector
Standard
i HBN - Ingestion, Cancer
i HBN - Ingestion. Cancer
1 HBN - Ingestion. NonCancer
losure
'ation (yr)
1 7
1 JU!
• 1
itift cation
_T
i
ni ards" button to seva your selection. J
Next. »
E. Text Boxes for
data entry
Figure 5.5 Example IWEM Screen Identifying Several Types of Controls.
Dialog and Message Boxes
Dialog boxes appear throughout the IWEM software as additional data entry
screens containing one or more of the controls mentioned above (i.e., see Figure 5.35: the
Climate Center List dialog box), or as a way of informing the user (i.e., see Figure 5.3:
the Full Source message box). Data entry dialog boxes usually appear as a direct result of
clicking on a command button, whereas message boxes appear as the result of a user's
input, or the model's calculation.
5-11
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IWEM User's Guide Section 5.0
List Boxes
List boxes are used to display a list from which you can select one or many of the
listed items. In Figure 5.4, the list box (box A) displays all of the constituents in the
IWEM database that can be used in a Tier 2 analysis. This list permits multiple selections
and is described in more detail in Section 5.5.1.6 of this document.
Radio Buttons
Radio buttons always appear in a set of two or more options and have a variety of
uses. In the screen in Figure 5.4, the radio buttons (box C) control the display of
constituents in the list box (box D). In the screen in Figure 5.5, you can use the radio
buttons to select one of the available standards for the current constituent (box C). The
selection is not recorded, however, until the APPLYSTANDARD command button is pressed.
Data Grids
Data grids are used in many different ways throughout the IWEM software: to
display data, to accept data, a combination of data display and entry, or to select a grid
item that affects other controls on a screen. As a user, you will need to manipulate these
grids to view, enter and select information. The grids are very similar to a spreadsheet in
that the 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 ITABl or lARRO/Vl keys
as explained in Section 5.2.2.
Selecting a particular row of the grid is accomplished by clicking on the cell in
that row or along the left border of the grid or using the ITABl or lARROM keys to move to a
particular row. In the screen in Figure 5.4, removing a constituent from the list displayed
in the data grid (box G) requires selecting the row of the grid and then clicking the
command button with the left-pointing arrow (box E). Selecting a row in a grid is also
required when you are assigning a standard to a constituent on the screen presented in
Figure 5.5. When moving from row to row in this grid (box A), the radio buttons (box C)
and text boxes (box E) change as a function of the constituent displayed in the selected
grid row. In addition, when a standard has been selected, the last column in the grid is
updated to reflect the selected standard.
5-12
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IWEM User's Guide Section 5.0
Command Buttons
Command buttons are used throughout the tool to execute an action, to navigate
from screen to screen, to verify a choice, or to acknowledge a message. Figure 5.4 shows
a screen from IWEM where command buttons are used for various purposes: navigation
(boxes D, H), moving information (box E), and initiating some action (box F). Command
buttons are activated by a mouse click or by pressing the (ENTER key when the button is
highlighted or active. The screen in Figure 5.5 (box D) uses a command button to verify a
selection made with a radio button group and then updates a cell in a data grid with the
selected standard.
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, the list may be modified by the user. In Figure 5.6, you
can select from the list of chosen constituents (box A) to view and/or edit constituent
properties. The data grids are updated based upon the selection in the drop-down list. In
Figure 5.7, a drop-down list is used to choose from a pre-defined list of options (box A),
however, you may enter your own data. This type of control is usually referred to as
"combo" box control: a combination of a text box control and drop-down box control.
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IWEM User's Guide
Section 5.0
A. Drop-down lists
to choose item
MTler2Input
Select a constituent from the first list below. Properties of tl e si
properties of a daughter product select it from the second ist
Waste Constituents: 1107-13-1 Acrylonitnle
Daughter products: j
Default Properties of 107-13-1 Acrylomlrile
Constituent Properties (21 ) f Reference GW Cone. (22)
lected constituent will be displayed in the grids. To see the
User Supplied Property Values
Property
KocfL/kg)
Rate
Acid-catalyzec
hydrolysis-Ko
(/mol/yr)
Value
Source
815E-OliuSEPA1993a
V ilue | Source
5.QOE-Q2 USEPA, 199
PropenV J Value | Source
« Previous
Next»
Figure 5.6 Example IWEM Screen Identifying Several Types of Controls.
5-14
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IWEM User's Guide
Section 5.0
A. Drop-down list
for data entry or
selection
H Tier 2 Input
WMU Type (16) | WMU Parameters (17) ]' Subsurface Parameters (18) | inn
This screen allows you to enter or change surface impoundment parameters. Justifications for parameters are r
Distance to Nearest Surface Water Body (m) (Unknown, but less than 2000m (Model uses 360m)
•quired.
Value Data Source
150 Default
0 Default
2 Default
1234556 Topo maps
1.6 Initial Estimate
, 50 Default
« Brevious
Apply P,efau Its
tlexl»
to populate
data grid
Figure 5.7 Example IWEM Screen Identifying Several Types of Controls.
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Section 5.0
5.2.3 How Do I Use Online Help?
IWEM provides online hELP that can be accessed from any screen either by
pressing the IF1I key or by selecting |hELP| CONTENTS] from the IWEM menu bar. Selecting
|hELP| GONTENTBl from the IWEM menu bar will cause the screen shown as Figure 5.8 to be
displayed.
Help Topics: Industrial W
Contents Index I Find
Click a book, and then click Open. Or click another tab, such as Index.
Program Overview
(J2) Working With IWEM
^ Program Components
^P Navigating the IWEM Interface
^P Understanding IWEM Inputs
^ Interacting with EPACMTP
^p Interpreting fWEM Results
^ IWEM Reports
(fl\ Help for Specific Dialogs
^^ Introductory Screens
^P Tier 1 Evaluation Screens
^ Tier 2 Evaluation Screens
^^ Windows Available at Any Time
Print...
Cancel
Figure 5.8 IWEM Online Help.
From this main hELP screen (shown in Figure 5.8), you can use the mouse or
keyboard keys to explore the IGONTENTSI tab which is automatically displayed by default, or
you can navigate to either of the other two tabs: I INDEX! and IFiNDl. On the IGONTENTSl tab,
you can double-click on the book icon to the left of each topic to expand that topic; some
main topics contain multiple levels of sub-topics, but after navigating down to the most
detailed level, a |hELP| screen will be displayed that contains descriptive text that explains
a particular feature of the IWEM software. Many of these text descriptions contain
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IWEM User's Guide Section 5.0
hyper-text links to related items in the online hELP; these hyper-text links are formatted
with colored and underlined text. Double-click on any hyper-text link to display detailed
information about that topic. On the llNDEXl 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 IDSPLAYl button. The IFlNDl tab enables you to search for
specific words and phrases in online hELP, instead of searching for information by
category. Just follow the on-screen prompts on the |FiND| tab to create and search a list of
words in online hELP.
Pressing the IF1I key will automatically display an online |hELP| screen that is
appropriate for the current IWEM screen that you are using. This information is similar
to that presented in Sections 5.4 and 5.5 of this document and is also presented in the last
topic listed on the IGoNTHsnBl tab: IhELP FOR SPECIFIC DIALOGS!.
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.
5.2.4 How Do I Save My Work?
You have several options within the IWEM software to save your analysis. After
performing a new Tier 1 or Tier 2 analysis, you can click on the ISAVEI button on the
Toolbar or choose IFlLElSAVEl or IFlLElSAVE Asl from the Menu Bar to launch the standard
Windows iSave Asl dialog box. If you open a saved analysis, and then make changes to it,
clicking on the ISAVEI button on the Toolbar or choosing IFlLElSAVEl from the Menu Bar
will overwrite the contents of your original file with the current analysis settings; if you
want to save these changes to a new file, you must choose IFlLElSAVE Asl from the Menu
Bar. If you forget to save before trying to exit the IWEM software, a dialog box will
automatically ask if you want to save your data before exiting the software.
For each saved analysis, IWEM creates two project files:
• *.wem file
• *.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.
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IWEM User's Guide Section 5.0
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 Tier 2
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 either
the Tier 1 or Tier 2 analysis to create the corresponding results.
You may open a previously saved IWEM analysis by clicking on any one of the
following options:
• lOPENl button on the Toolbar
• IFlLE|OPENl selection from the Menu Bar
• IOPEN SAVED ANALYSIS (*.WEMFiLE)l radio button from the I IWEM ANALYSIS
OPTIONS! dialog box (see Item B in Section 5.3)
Once the lOPENl dialog box is displayed, highlight the appropriate file and click the
lOPENl button to open the desired file. You will then see a dialog box in which you can
specify what type of analysis you want to perform - Tier 1 or Tier 2 (see Item B in
Section 5.3).
5.2.5 How Do I Get Help If I Have a Problem or a Question?
If you have a copy of the Guide CD, you can open and read this User's Guide on-
screen while the IWEM software is running on your computer. You may 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 learning to use the IWEM software or to use the IWEM online |hELP|
(see Section 5.2.3). This section of the User's Guide contains screen-by-screen
instructions for using the software.
A dialog box containing a keyword or parameter definition used in IWEM can be
displayed by clicking on any underlined text in the Data Requirements screen (see Screen
3, in Section 5.3). These definitions can also be displayed at any time by choosing
| DEFINITION WNDCW from the I-ELP| menu.
If you have a technical question about installing or running the IWEM software,
you should contact the RCRA Information 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 information center cannot provide regulatory interpretations.
To get your technical questions about the IWEM software answered, please
contact the RCRA Information Center in any of the following ways:
548
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IWEM User's Guide Section 5.0
• E-mail: rcra-docket@epa.gov
• Phone: 703-603-9230
• Fax: 703-603-9234
• In person: Hours: 9:00 am to 4:00 pm, weekdays, closed on Federal Holidays
Location: U. S. EPA
West Building, Basement
1300 Constitution Avenue, NW
Washington, DC
• Mail: RCRA Information Center (5305W)
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
When contacting the RCRA Information Center, please cite RCRA Docket
number: F1999-IDWA-FFFFF.
5.2.6 How Do I Begin Using the IWEM Software?
The following subsections provide 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
Tier 2 input data are required and others are optional). The guidance will assist you in
performing a Tier 1 and a Tier 2 analysis for an industrial WMU to determine the
minimum recommended WMU design that will be protective of ground water. You will
not need all the information provided here because this document addresses all WMU
liner designs and several different levels of site-specific data for Tier 2. Follow only
those subsections that are applicable to your particular waste and WMU.
5.3 Introductory Screens (Screens 1 through 5)
The text on Screens 1 through 5 provides a brief introduction to the IWEM
software. 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, a summary of model limitations, and the option to begin a Tier 1 or Tier 2
evaluation.
The key operational features of the introductory screens are as follows.
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IWEM User's Guide Section 5.0
The features identified in Figures 5.9 through 5.13 are explained in more detail in
the following paragraphs.
A. Explanatory Text about IWEM
The following five screens contain brief introductory information on the following
aspects of the software:
• Screen 1: An overview of the IWEM software
• Screen 2: How to use IWEM
• Screen 3: Data requirements
• Screen 4: Model limitations
• Screen 5: Evaluation types
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Section 5.0
IWEM Overview (1)
Purpose: This program is designed to give facility managers, regulatory agency staff, and
citizens a simple-to-use tool to evaluate appropriate liner systems for landfills, surface
impoundments, and waste piles, and to evaluate whether wastes are suitable for land application.
How: This program provides the results of fate and transport modeling of constituents from a
waste management unit through subsurface soils to ground water. The model contains two
evaluation tiers. Tier 1 provides recommendations for each type of waste management unit,
based on estimated constituent concentrations in leachate from the unit. Tier 2 provides
location adjusted recommendations that are more tailored to a specific site, while still less
resource intensive than a detailed site-specific analysis.
Tier 2 allows the user to enter data for a limited
waste characteristics, to get recommendations
i umber of site-specific parameters, along with
or protective unit design and management.
Results: The model provides four types of recor imendations
(Show these introductory screens each time IWEM starts'
Next»
Figure 5.9 Introduction: IWEM Overview (1).
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Section 5.0
Introduction
Use of IWEM (2)
This model is in final form and can be used to assist in waste management decision-making.
We strongly encourage the user of this model to work with his/her State Agency prior to using this
tool or making decisions regarding design standards for new waste management units.
We also strongly encourage users to review the "Assessing Risk" section of Chapter 7 ("Protecting
Ground-water Quality") in the Guide for Industrial Waste Management for a description of the model
and a discussion of key parameters and critical issues that affect modeling results.
'Show these introductory screens each time IWEM starts
« Erevious
Figure 5.10 Introduction: Use of IWEM (2).
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Section 5.0
Data Requirements (3)
ForT
er 1, the model requires the following information:
wMLLtype,
Estimated leachate concentration for each constituent.
For Tier 2, the model requires the following location-adjusted information:
WMU type,
WMU area,
WMU depth for landfills or ponding depth for surface impoundments
Estimated leachate concentration for each constituent,
WJyiyjjifjJtat]flILtate(user-defined or select from database with sgJLtyjje
and geographic location for all WMUs except surface impoundments)
Regional infiltration rate (select from database with soil type and geographic location)
For Tier 2, the model uses the following optional information (The user may
Show these introductory screens each time IWEM starts.
« Erevious
Next»
Figure 5.11 Introduction: Data Requirements (3).
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IWEM User's Guide
Section 5.0
Model Limitations (4)
As is true of any model, this model is based on a number of simplifying assumptions which may
make the use of this model inappropriate in certain situations. This model should not be used in the
following situations:
1) If the soil and aquifer cannot be treated as uniform porous media, each consisting of a single
layer. For instance, if the aquifer is composed of limestone or fractured bedrock, ground-water flow
is likely to be significantly influenced by preferential pathways, such as solution cavities or fractures.
The model does not account for the presence of preferential ground-water flow pathways or layering
in the unsaturated or saturated zones.
2) If there is a mobile oil phase or other Non-Aqueous Phase Liquid (NAPL) present at the facility.
Significant contaminant migration may occur within such a phase (due to the differing densities of
NAPL and ground water), which is not accounted for in the model.
(i
These are the most important limitations of the model. The IWEM Background Document discusses
' (I
« Previous
Figure 5.12 Introduction: Model Limitations (4).
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IWEM User's Guide
Section 5.0
Introduction
Choose Evaluation Type (5)
Select the Tier 1 evaluation to compare your estimated leachate concentrations against the
thresholds calculated by the EPA using national data. Choose the Tier 2 evaluation to investigate the
impact of using model input parameters that are specific to a particular facility and location. First
time users may want to begin with the Tier 1 evaluation and then proceed to the Tier 2 evaluation, if
desired.
I p [Show these introductory screens ettdh time IWEM starts,]
«Previous • Tier 1 Evaluation
Tier 2 Evaluation
Figure 5.13 Introduction: Choose Evaluation Type (5).
B. Uncheck to Skip Introductory Screens at Next Start-up
After reading this introductory information, you can uncheck the SHO/VTHESE
IMTRODUCTORYSCREENS EACHTllVE IWEMSfARTS check-box at the bottom of the screen to
prevent these screens from being displayed the next time the program is run. The
introductory information can be viewed at any time by choosing INTRODUCTION) from the
I HELP menu.
If you uncheck this check box, the next time you launch IWEM, you will see the
following dialog box:
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IWEM User's Guide
Section 5.0
f jStart New Tier 1 Analysis!
r Start New Tier 2 Analysis
<"" Open Saved Analysis f.wem File)
Ogen
Select the ISfART NBA/TIER 1 ANALYSIS! radio button and click the lOPENl button to start
a new Tier 1 analysis; doing so will take you directly to the WMU Type (6) screen - the
first Tier 1 input screen.
Select the ISfARTNEWTiER 2 ANALYSIS! radio button and click the lOPENl button to start
a new Tier 2 analysis; doing so will take you directly to the WMU Type (16) screen - the
first Tier 2 input screen.
Select the IdPEN SAVED ANALYSIS f.wem RLE)| radio button and click the IdPENl button to
open a previously saved IWEM analysis; doing so will launch the familiar Windows
lOPENl dialog box where you can navigate to the folder and file containing the previously
saved IWEM analysis. This file will have a ".wem" file extension. After you select the
appropriate file, the following dialog box will be displayed:
Open
f* Tier 1 Analysis
C Tier 2 Analysis
You can select the ITlER 1 ANALYSlSl radio button and click the lOPENl button to open
your saved analysis in Tier 1; doing so will take you directly to the WMU Type (6) screen
- the first Tier 1 input screen. Or, you can select the ITlER 2 ANALYSlSl radio button and click
the IdPENl button to open your saved analysis in Tier 2; doing so will take you directly to
the WMU Type (16) screen - the first Tier 2 input screen. By default, IWEM will open
the file for a Tier 1 analysis.
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IWEM User's Guide Section 5.0
C. Go to Next IWEM Screen
Click the NEXT button at the bottom right of the screen to proceed to the next
screen.
D. Go to Previous IWEM Screen
Click the PREVIOUS button at the bottom left of the screen to go back to the
previous introductory screen.
E. Click to Display More Information
Clicking on any keyword displayed in blue underlined text will 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 Data Requirements (3) screen.
F. 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.
G. Go to WMU Type (6) screen
Click on the TIER 1 EVALUATION | button to begin a Tier 1 analysis for your waste.
Generally, you should perform the Tier 1 analysis first and then proceed on to the Tier 2
analysis, if appropriate. A Tier 1 evaluation begins at WMU Type (6) screen (Section
5.4).
H. Go to WMU Type (16) screen
Click on the TIER2 EVALUATION) button to begin a Tier 2 analysis for your waste.
Generally, you should perform the Tier 1 analysis first and then proceed on to the Tier 2
analysis, if appropriate. However, if desired, you can proceed directly to Tier 2 by
clicking this button. A Tier 2 evaluation begins at WMU Type (16) screen (Section 5.5).
You can also begin an evaluation by using either of these methods:
• Click on the | EVALUATION) menu and choose from | TIER 11 or TIER2 , or
• Click on the T1 or T21 toolbar buttons.
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IWEM User's Guide Section 5.0
5.4 Tier 1 Evaluation
The IWEM Tier 1 analysis automates the comparison of your expected leachate
concentration^) with the Tier 1 LCTV lookup table to produce waste management
recommendations for your particular waste. The IWEM Tier 1 analysis consists of four
main screen groups: Tier 1 Input, Tier 1 Output (Summary), Tier 1 Output (Details), and
Tier 1 Evaluation Summary. Each of the first three of these groups contains several
screens.
The Tier 1 Input screen group consists of three screens:
• WMU Type (6)
• Constituent List (7)
• Leachate Concentration (8)
The Tier 1 Output (Summary) screen group consists of two screens:
• MCL Summary (9)
• HBN Summary (10)
The Tier 1 Output (Details) screen group consists of three screens:
• Results for No Liner (11) [based on MCL and HBN1
• Results for Single Liner (12) [based on MCL and HBN1
• Results for Composite Liner (13) [based on MCL and HBN]
The overall Tier 1 result is then displayed on the Tier 1 Evaluation Summary (14)
screen.
The available options and data displayed on each of these screens are explained in
the following sections.
5.4.1 Tier 1 Input Screen Group
5.4.1.1 Tier I Input: WMU Type (6)
This is the first input screen for a Tier 1 evaluation; you can select the WMU type
and enter facility identification information on this screen, as explained below.
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IWEM User's Guide
Section 5.0
WMU Type (6)
- Self ct WMU Type
P Landfill
<~ Surface Impoundment
r Waste Pile
f Land Application Unit
Facilily Identification Information
Southern Industries Landfill
122 Industrial Ave
Raleigh
NC
27611
October 31,1998
±d
Mext»
Figure 5.14 Tier 1 Input: WMU Type (6).
The features identified in Figure 5.14 are explained in more detail in the following
paragraphs.
A. Choose WMU Type
First, select one of the following choices from the | SELECT\AMJTYPE) option list by
clicking on the appropriate option button:
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IWEM User's Guide Section 5.0
• Landfill
• Surface Impoundment
• Waste Pile
• Land Application Unit
B. Enter Descriptive Facility Identification Information
Then, in the text boxes located in the lower half of the screen, enter the following
information about the WMU being evaluated:
Facility name
Address of the WMU (street, city, state, zip)
Date of waste constituent sample analysis
User name (name of the person performing the liner evaluation)
Any additional identifying information that you would like to include
All facility identification information will be included on the printed Tier 1, and if
performed, Tier 2 Evaluation Reports.
C. Go to Next IWEM screen
After entering your site information, click the | NEXT| button at the bottom right of
the screen to proceed to the next screen.
5.4.1.2 Tier I Input: Constituent List (7)
On this screen you can, select constituents expected in leachate by searching for
the name or CAS number or by scrolling through the displayed list of IWEM constituents,
as explained below.
What waste constituents can I enter in the IWEM software?
On the Constituent List (7) screen, you will find the list of waste constituents that
are included in the IWEM database. This list of constituents includes 206 organics and
20 metals. These constituents are presented in Appendix A.
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Section 5.0
G Search for
constituents
by name or
CAS#
1
D. ADD highlighted
constituents to
SELECTED CONSTITUENTS!
list
letter Unpul :.J\
1 WMUType(6) Constituent
: SearaBy
Constituent Ne
CAS Hum
ime| a
beri
r
All Constituents
83-32-9 Acenaphthene ~*j
75-07-0 Acetaldehyde [Ethanal] j
75-05-8 Acetonitrile (methyl cyanide)
98-86-2 Acetophenone
1 07-02-8 Acrolem
79-06-1 Acrylormde '
79-1 0-7 Acrylic acid [propenoic acid]
1 07-1 3-1 Acrylonilnle
309-00-2 Aldrm
1 07-1 8-6 Allyl alcohol
62-53-3 Aniline (benzenearnme)
120-1 2-7 Anthracene
1
»
II 7441 l-3fi-f] Anlimnnu ^^^
[7440-38-2 Arsenic
«£revious
zj
B. Choose sorting A. Filter
order for " ALL CONSTITUENTS
[ALL CONSTITUENTS] ist
IPl.'"' • -JsJxJ
H>, -;,J Y,\. JSJ =J«*— 1
.ist (7) Leachate Concentration (8)
tort By • Type of Constituent
Constituent Name ; «" All CansBtuenis •
. r Organics 1
CAS Number • |
; f~ Metals 1
1
!^J
Constitienls
71-43-2 Benzene
75-09-2 Methylene Chloride (Dichloromethane)
7410-36-0 Antimony
f
**»
C. Select constituents F. REMOVE highlighted E. List of
to be included in constituents from constituents
Tier 1 analysis ^SELECTED CONSTITUENTS! to be included
list in Tier 1 analysis
Figure 5.15 Tier 1 Input: Constituent List (7).
The features identified in Figure 5.15 are explained in more detail in the following
paragraphs.
A. Filter AnGONSm7UENTs| List
You can choose to display only organics, only metals, or all constituents by
clicking one of the radio buttons within the frame titled | TYPEOFCoi\BTlTUEl\n"|.
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IWEM User's Guide Section 5.0
B. Choose Sorting Order for ALL CCNSTnUENlS\ List
You can determine whether the constituents are sorted by name or by CAS
number by clicking one of the radio buttons within the frame titled | SORT BY .
C. Select Constituents to be Included in Tier 1 Analysis
The following keyboard functions simplify the selection of more than one waste
constituent:
• To add a group of constituents that are displayed sequentially in the list (that
is, one after another without any non-selected constituents in the middle),
click on the first desired waste constituent, press down the SHIFT| key, and
then click on the last desired waste constituent. All waste constituents listed
between the first and last chosen constituents should now be highlighted.
• To add a number of constituents that not are displayed sequentially, click on
the first waste constituent, and then hold down the | CONTROL | (Ctrl) key while
selecting additional constituents using the mouse.
Once your selection is complete, use the ADD button (described below) to
transfer all the highlighted constituents to your list.
D. Add Highlighted Constituents to \ SELECTED CONSTITUENTS List
Once the appropriate constituents are highlighted in the list (on the left of the
screen), you can click the ADD button ,XJ in the center of the screen to transfer it to your
list of constituents present in the leachate (on the right side of the screen). Note that a
waste constituent can also be added quickly to your list by double-clicking on it in the list
on the left. Likewise, multiple selections can be added using the same technique:
double-clicking on your highlighted list of constituents once you have created it using the
| SHIFT| or CONTROL | keys, as described above.
E. List of Constituents to be Included in Tier 1 Analysis
After adding a constituent to your analysis, that constituent's name and CAS
number will appear in the | SELECTED CONSTITUENT| listbox on the right side of the screen.
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F. Remove Highlighted Constituents from SELECTED CONSTITUENTS | List
Similarly, you can click the
REMOVE | button _5J to remove highlighted
constituent(s) from your list of selected constituents. You may also use the short-cut
techniques previously described in item D above ( SHIFT and CONTROL keys, double-
clicking) to delete constituents.
G. Search for Constituents by Name or CAS Number
As an alternative to selecting constituents by scrolling through the display list, you
can search for constituents by entering their name or CAS number in the SEARCH BY box
at the top-left of the screen. IWEM will match the name or CAS number to its database
while you type and as soon as you have typed in enough information to identify one of the
listed constituents, that waste constituent will be highlighted in the list. You can use the
ARROW keys on the keyboard to move up or down the list if the highlighted constituent is
not exactly the one you intended to select.
You can move through the constituent display list to select a particular constituent
by using any of these methods:
To move through the list of waste constituents:
1) Use the scroll bar at the right of the displayed list
2) Use the | ARROW| keys on the keyboard (once one
constituent in the list is selected)
3) Type in the constituent name or CAS number in the
SEARCH BY| text box
Once your list of waste constituents is complete, you can proceed with the Tier 1
evaluation by clicking on either the screen titled
button at the bottom of the screen.
LEACHATECCNCEMTFiATlCN or the NEXT
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5.4.1.3 Tier I Input: Leachate Concentration (8)
On this screen, you can enter the expected leachate concentration (in milligrams
per liter [mg/L]) for each selected waste constituent, as explained below. Please see
Chapter 2 - Waste Characterization of the Guide for analytical procedures that can be
used to determine leachate concentrations for waste constituents.
The Tier 1 Evaluation cannot be performed until an expected leachate
concentration is entered for each selected waste constituent.
Constituent List (7)
_ n xi
Leachate Concentration (8)
CAS
Constituent Name
Esi
mated Leochate Concentration
(mg/L)
Benzene
76-09-2 Methylene Chloride (Dichlotomethane)
7440-36-0 Antimony
0,01
0.02''
003
« Bfevious
Figure 5.16 Tier 1 Input: Leachate Concentration (8).
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IWEM User's Guide Section 5.0
The features identified in Figure 5.16 are explained in more detail in the following
paragraphs.
A. List of Constituents to be Included in Tier 1 Analysis
The constituent names and CAS numbers for all selected waste constituents will
appear in the table on this screen.
B. Enter Expected Leachate Concentration^)
This table is similar to a spreadsheet. Using the mouse, click on the first empty
cell in the | ESTIMATED LEACHATE CONCENTRATION column, and type in your expected leachate
concentration. The concentration must be entered in units of mg/L, and cannot exceed
1,000 mg/L.1 The IWEM software will display a warning message similar to the one
shown below (after the description of item C) if you enter an expected leachate
concentration that exceeds the solubility of that constituent, as cited in the IWEM
database. If you accidentally entered the wrong value, click the | YES| button and correct
the expected leachate concentration on the Leachate Concentration (8) screen. 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.
After entering the expected leachate concentration for the first selected
constituent, then click on the cell below, press the | TAB| key, or press the ARROW-DOWN
key to move to the next cell and enter the next concentration. Repeat this process until
you have entered expected leachate concentrations for all waste constituents. You can
move up and down through the list of leachate concentration values and edit them by
using the ARROW-UP and ARROW-DOWMJ keys on your keyboard or by using the mouse to
click on the value that you want to change and entering a new concentration value.
C. Perform Tier 1 Analysis
Simply click on the | NEXT| button at the bottom right of the screen to perform the
Tier 1 evaluation and view your results. Before allowing you to proceed, IWEM will
check to make sure that you have entered a leachate concentration for all constituents, and
will compare the leachate concentration(s) to the corresponding solubility limits in the
EPA does not expect leachate concentrations from units covered by this guidance to exceed 1,000 mg/L for
a single constituent. Additionally, the fate and transport assumptions in IWEM may not be valid at high
concentrations. Therefore, the EPA has designed IWEM so that the input expected leachate concentrations
are not allowed to exceed 1,000 mg/L.
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Section 5.0
constituent database. If any leachate concentration^) exceed the solubility limit, the
following warning message will be displayed to alert you and to ask if you want to change
the concentration value. If you select No|, the analysis will proceed.
The leachate concentration specified for Acenaphthene is greater than the cited solubility value in
the database of 4.24 mg/l.
Do you want to change the leachate concentration ?
Ves
5.4.2 Tier I Output (Summary) Screen Group: MCL Summary and HBN
Summary (9 and 10)
The IWEM Tier 1 analysis is essentially a query to an existing database of
modeling results. The results of this database query are immediately presented in
summary form on screens 9 and 10, as shown below in Figures 5.17 and 5.18.
5-36
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IWEM User's Guide
Section 5.0
JlM Tier 1 Output (Summary)
MCL Summary (9) I J_
HBN Summary (10)
CAS Number ) Constituent Name
Minimum Liner Recommendation
75-U9-C
744U-36 U
_Ben;ene
Metliylene Chloride (Diclilorornetlionei
Based on consideration of the MCL values of all listed constituents, the Single Liner
minimum liner recommended is:
« Previous
Detailed Results
C. Go to
Results - No Liner (11)
screen
B. Overall
Tier 1 liner
recommendation
based on MCLs
D. Go to
HBliSun
screen
Figure 5.17 Tier 1 Output (Summary): MCL Summary (9).
5-37
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IWEM User's Guide
Section 5.0
[•Tier 1 Output (Summary)
MCt Summary (9)
J • HBN Summary (10)
CAS Number Constituent Name
Minimum Uner Recommendation
71-43-2 .Benzene
75-09-2 Methylene Chloride (Dichloromethane)
7410-36-0 Antimony
Based on consideration of the HBN values of all listed constituents, the
minimum liner recommended is:
Composite Liner
« grevious
Detailed Results
Becommendation »•
C. Go to
Results -No Liner (I I)
E. Go to
lierj Eyaluation
Summary (14)
Figure 5.18 Tier 1 Output (Summary): HBN Summary (10).
The features identified in Figures 5.17 and 5.18 are explained in more detail in the
following paragraphs.
A. Tier 1 Liner Recommendations Based on MCLs/HBNs
The results of the Tier 1 Evaluation are first presented on-screen in summary
form. The summary results are divided into two screens: one, for LCTVs calculated
based on MCLs; and one, for LCTVs calculated based on HBNs.
5-38
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IWEM User's Guide Section 5.0
Not all waste constituents have both an MCL and an HBN. The MCL summary
screen provides a minimum liner recommendation for each of the selected constituents
that have an MCL. Likewise, the HBN screen presents a minimum liner recommendation
for each of the selected constituents that have an HBN. These recommendations are
based on a comparison of the expected leachate concentration for that constituent to the
calculated LCTV using the constituent-specific MCL or HBN. For those constituents that
have more than one HBN, the LCTV is calculated for each HBN, and the HBN that
produces the lowest LCTV is used to determine the Tier 1 liner recommendation. The
value and type (pathway and effect) of the controlling HBN are shown on the Detailed
Results screens (11 through 13).
For each constituent in an IWEM Tier 1 evaluation, a liner recommendation that
is protective is presented in green text. If the composite liner scenario is not protective,
this message is presented in red text. If a constituent does not have a liner
recommendation on the MCL Summary (9) screen because it does not have an MCL, this
message is presented in black text.
B. Overall Tier 1 Liner Recommendation Based on MCLs/HBNs
This text box displays an overall minimum liner recommendation which is based
on consideration of all waste constituents.
The overall liner recommendation may be different based upon whether HBNs or
MCLs are being used. Depending upon the waste constituents being evaluated and the
appropriate RGC for each, you may have to create for yourself a final list of LCTV values
and minimum liner recommendations, some based on MCLs and some based on HBNs.
You should obtain direction from your state regulatory authority regarding which RGC
should be used for the Tier 1 evaluation of a particular waste.
C. Go to Results - No Liner (11) screen
Clicking on this button will take you to a detailed listing of the Tier 1 results,
including the constituent-specific LCTVs for all evaluated liner scenarios.
D. Go to HBN Summary (10) screen
Clicking on this button will take you to minimum liner recommendations based
on a comparison of expected leachate concentrations to calculated LCTVs.
5-39
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IWEM User's Guide Section 5.0
E. Go to Tier 1 Evaluation Summary (14) screen
Clicking on this button will skip over the Tier 1 detailed results and will take you
directly to the Tier 1 Evaluation Summary Screen where you can choose to view the Tier
1 report or proceed on to a Tier 2 Evaluation.
5.4.3 Tier 1 Output (Details) Screen Group: Results - No Liner, Single Clay Liner,
and Composite Liner (11,12, and 13)
Clicking the | DETAILED RESULTS button leads you to the detailed results of the Tier
1 Evaluation. This screen group consists of the following three screens, one for each liner
scenario: no liner; single clay liner; and composite liner. Each screen presents results
based on MCL and HBN reference concentrations for one of the liner scenarios.
The layout of these screens is the same, the only difference is the liner scenario,
which is indicated on the tab showing the screen name.
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IWEM User's Guide
Section 5.0
MTIer 1 Output (Details)
Results - No liner (11)
Results - Smgis Liner (12)
B. Results of
comparison between
LCTV and expected
leachate concentration
Res (Its - Composite Liner (13)
Results Based on MCL
CAS
Constituent
MCLJmg/L)
Leadiate
Concentrator) (mg/L)
DAF
CTV
Protective
71-13-2 Benzene
75-09-2 Methylene Chloride
(Dichloiometharse)
744Q-36-0 Antimony
Resyfc Based on HBN
CAS
Constituent
HBN
Leachate
Concerrtrefion (mg/Lj
Off
LCTV (mg/L)
ProtediveT
Cont oiling Palhway t, Effect
71-13-2 Benzene
Inhalation Cancer
75-09-2 Methylene Chloride
(Dichloi'ornethsrse)
7440-36-Q Arttfrnony
Ingestion Cancsf
Ingestion Non-cancer
* Some LCWs mey be capped Detests are §sveri MI T»r1 Report See Use^s Guide or Help for
« Erevtous
ults
F. Go back to
Summary Results (9)
Figure 5.19 Tier 1 Output (Details): Results - No Liner (11).
5-41
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IWEM User's Guide
Section 5.0
1 Output (Details)
R,esults-NoLiner(1t)
Results -Single Liner (12)
B. Results of
comparison between
LCTV and expected
leachate concentration
Res
s - Composite Liner (1 3)
Results Based on MCL
Constituent
71-43-2 Benzene
75-09-2 "wethylens Chloride
(Dichloromethane)
7410-3B-0 'Antimony
MCL(mg/L)
Leochate
Concentration (mg/LJ
BAF
IDTV
(i ig/L)
PtotertivE
0.005
0.005 '
0.006
003 N/A
0.031
0031
004
Results Based on HBN
CAS
Consituent
HBN
(rng/L)
Leachate
Concentration (mg/L)
DAF
LCTV
Pfotedive?
Controllina Palhwoy 4 Etect
71-13-2 Benjene
75-09-2 Methylerre Chloride
{Dichioromethane)
7-MO-36-0 Antimony
001
6! 00097 Mr, Inha ation Cancer
6.2 0.081
0 068
iriqec-tson Cancer
Inqestion Non-cancer
* Some LCTVs may be capped Details are giver m Tisrl Report See User's GMsde t» Help for
« Previous
Summary Results
F. Go back to
Summarv Results (9)
Figure 5.20 Tier 1 Output (Details): Results - Single Clay Liner (12).
5-42
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IWEM User's Guide
Section 5.0
B. Results of
A. Composite- bet,v
liner LCTV fnd
based on MCL leac
coin
IT».O«P«
Results - No Uner (1 1) | Res
ute- Single Uner(U)
Results Based on MCL
>
—
CAS Constituent MCL{mg/L)
Con
71-43-2 E-iicr. 0.005
75-09-2 » leth I- is Chlor de 0.005
j,Didi.tjrumethane)
7140-3M) Antimony 0006
Leachate DAF
centration (mg/L)
CTV Pit
OU1 i 1 E*04 lc
( I '
OIL k C C*05 1U! 1
003 N/A 100n
-een LCTV G Go to
expected Tier 1 Evaluation
late Summary (14)
:entration screen
— 1
^esuRs - Composite Liner (1 3)
Active?
1
Results Based on HBN
CAS Constituent HBN Lead-
(mg/L) Concentrati
71-43-2 Benzene 00016
75-09-2 Methylene Chloride 0013
(Dicfitoromethane)
7110-36-0 'Antimony 00098
* Sonw LCTVs rMy few tsf'^0d ppwib we y- en ^ TIW Rapo** S^LKct
« Previous A
F. Go back to
Summary Results
screen
ate OAF LCTV Protective? Controlling Pathway* Effect
on (mg/L) (mg/L)
0 01 1 90E»IM
002' 630E-05'
003 N/A'
'; 0 flde o? Hslp^Drffior0)nl
Nummary Results
C. Compo
(9) liner LCT1
based on I
115 ''.'.=.;
1 Ih e;.
•
inijii 'IP,.
•rniation.
Inha ation Cancer
Irsgestion Cancer ^
» ''
iriges'son Non-cancer
Eecomm sndatlon M
Hlx,|
i
D. Results of c URKJ
*J £TPa"TrTV Pathway
1BN ^SecLtCedTV ^ ^
concentration
Figure 5.21 Tier 1 Output (Details): Results - Composite Liner (13).
5-43
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IWEM User's Guide Section 5.0
The features identified in Figures 5.19 through 5.21 are explained in more detail
in the following paragraphs.
A. Liner-Specific LCTV based on MCL
The Tier 1 constituent- and liner-specific LCTV is displayed on this screen. An
LCTV is the maximum concentration of a constituent in the waste leachate that is
protective of ground water. That is, if the concentration in the leachate does not exceed
the LCTV, then the modeled concentration in ground water (at the modeled well) will not
exceed the MCL for that constituent.
B. Results of Comparison between LCTV and Expected Leachate Concentration
The data displayed in the top window of the screen present the result on which the
liner recommendation is based for each selected constituent. The last column in the table
(with the header PROTECTIVE? ) tells you whether or not the specified liner is protective of
ground water for that constituent. This determination is made by comparing the entered
leachate concentration with the LCTV calculated from the MCL. If the expected leachate
concentration is greater than the LCTV, the liner is not recommended as being protective
("No"), whereas, if the expected leachate concentration is less than the LCTV, the liner is
recommended as being protective ("Yes"). If the LCTV is not calculated for that
constituent because the MCL is not available, "NA" (not applicable) is displayed in this
cell.
To properly interpret the results of the Tier 1 Evaluation, you should consult with
the appropriate state regulatory agency to determine which RGC should be used for each
constituent of concern. For wastes with multiple constituents of concern, you may need
to construct your own final list of liner recommendations, some from LCTVs based on
MCLs and some from LCTVs based on HBNs.
For waste streams with multiple constituents, the most protective liner specified
for any one constituent is the overall recommended liner type.
C. Liner-Specific LCTV based on HBN
The Tier 1 constituent- and liner-specific LCTV is displayed on this screen. An
LCTV is the maximum concentration of a constituent in the waste leachate from a
modeled WMU that is protective of ground water. That is, if the concentration in the
leachate does not exceed the LCTV, then the modeled concentration in ground water (at
the modeled well) will not exceed the HBN for that constituent.
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IWEM User's Guide Section 5.0
D. Results of Comparison between LCTVand Expected Leachate Concentration
The data displayed in the bottom window of the screen present the liner
recommendation for each selected constituent. The column with the header PROTECTIVE?
tells you whether or not the specified liner is protective of ground water for that
constituent. This determination is made by comparing the entered leachate concentration
with the LCTV based on the most protective HBN. If the expected leachate concentration
is greater than the LCTV, the liner is not recommended as being protective ("No"),
whereas, if the expected leachate concentration is less than the LCTV, the liner is
recommended as being protective ("Yes").
To properly interpret the results of the Tier 1 evaluation, you should consult with
the appropriate state regulatory agency to determine which RGC should be used for each
constituent of concern. For wastes with multiple constituents of concern, you may need
to construct your own final list of liner recommendations, some from LCTVs based on
MCLs and some from LCTVs based on HBNs.
For waste streams with multiple constituents, the most protective liner specified
for any one constituent is the overall recommended liner type. For constituents that have
more than one HBN, IWEM calculates the LCTV for each HBN and uses the HBN that
produces the lowest LCTV to determine the Tier 1 liner recommendation.
E. HBN Pathway and Effect
The exposure pathway and health effect for the HBN that is used to calculate the
LCTV, that is, the controlling HBN, is displayed in the column labeled | CONTROLLING
PATHWAY & EFFECT . IWEM accounts for direct ingestion and inhalation pathways, and
carcinogenic and non-carcinogenic health effects. The |H3N| column in the table shows
the value, in mg/L, of the controlling HBN.
F. Go Back to the Summary Results (9) screen
Clicking on this button will take you back to the Tier 1 MCL Summary Results
(9) screen.
G. Go to Tier 1 Evaluation Summary (14) screen
Clicking on the RECOMI\/ENDAT1ON| button on screen 13 will take you to the next
screen, the Tier 1 Evaluation Summary screen, where you can choose to view the
printable Tier 1 report, or proceed on to a Tier 2 evaluation.
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IWEM User's Guide
Section 5.0
5.4.4 Tier 1 Evaluation Summary Screen (14)
This screen (Figure 5.22) contains an overall summary of the Tier 1 evaluation
results along with options for further (Tier 2) evaluation. You can also view or print a
report of the Tier 1 evaluation by clicking on the REPORT button at the bottom of the
screen.
I •I Tier 1 Evalu< itioti Summary
To refine the
the Tier 2 ev<
Tier 1 Evaluation Summary (14)
The results of the Tier 1 analysis recommend the following design:
Composite Liner
liner recommendation, you may continue on with this program. You will be guided through _^_
luation, where you will have the opportunity to input data that are specific to your site.
IsJxJ
In addition to gathering site-specific data for a Tier 2 analysis, you may consider pollution prevention,
treatment, and more protective liner designs as well as consultation with regulators, the public, and
industry to ensure that wastes are protectively managed.
You may print the Tier 1 results before continuing or exiting this program.
« Previous
Report
Continue
Figure 5.22 Tier 1 Evaluation Summary (14).
The features identified in Figure 5.22 are explained in more detail in the following
paragraphs.
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IWEM User's Guide Section 5.0
A. Overall Tier 1 Liner Recommendation
The Tier 1 liner recommendation, based on consideration of all available RGC
values for each waste constituent, is displayed at the top of this screen. For landfills,
surface impoundments, and waste piles the available recommendations are: "no liner,"
"single clay liner," "composite liner," or "not protective." For LAUs, the available
recommendations are: "no liner" or "not protective." If your Tier 1 evaluation results in a
recommendation of "not protective," this indicates that either the chosen WMU is not
appropriate for managing your waste or you may need to continue to a Tier 2 or Tier 3
analysis to further evaluate your site.
B. List of IWEM Options
After reviewing your Tier 1 results on-screen, you can choose to continue by,
• Going back to the previous screens of the Tier 1 results by clicking on
the PREVIOUS button,
• Viewing the Tier 1 report by clicking the REPORT | button, or
• Beginning a Tier 2 Evaluation by clicking the CONTINUE button.
Or, you can choose to save your results and exit IWEM as described in Section
5.2.4 of this User's Guide.
C. Display Tier 1 Reports
Clicking on the REPORT button first displays a dialog box with the following
question:
| DO YOU WANTTOSHOWTHE DETAILS?
Choosing | No| will display a summary version of the IWEM Tier 1 Report. This
short version of the report includes the following information and data:
• Facility data entered on Screen 6
• List of selected constituents and their corresponding leachate
concentrations
• Tier 1 summary results for each selected constituent, based on both MCLs
and HBNs
• Tier 1 detailed results for each selected constituent, based on both MCLs
and HBNs, and including an explanation of any caps or warnings that
apply to the presented LCTVs
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IWEM User's Guide
Section 5.0
Choosing | YES| will display a complete version of the IWEM Tier 1 Report. This
detailed version of the report includes the following additional information and data:
• Constituent properties and RGCs for each selected constituent, including
full references for the data sources.
After making your choice, the selected report will be displayed on-screen. The
following toolbar buttons to print, save, and scroll through the pages of the report are
prov ided along the top of the screen:
Print the report; the PRINT | dialog box allows you to adjust printer
settings or print all or selected pages.
Export the report in order to save it to a file; after specifying the file
type, destination type, and the pages to be included, the | CHOOSE
EXPORT RLE | dialog box then appears; you can specify the file type, and
then select the file name and directory. The file types in this list are
dependent upon what software you have installed on your personal
computer. Most users will find that the option for PDF format will
produce a document-ready report.
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.
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IWEM User's Guide
Section 5.0
1QO%
Change the display size of the report.
A Tier 1 Report Includes:
1) List of selected waste constituent(s) and constituent
data
2) Minimum liner requirement based on MCLs
3) Minimum liner requirement based on HBNs
4) Data used to calculate the LCTV for each liner
An example Tier 1 report is included in this User's Guide in Appendix B.
D. Go to WMU Type (16) screen
Clicking here will take you to the Tier 2 Input screen. WMU Type, facility
description information, and your list of selected Tier 1 constituents are automatically
transferred to the Tier 2 analysis.
5.4.5 Exiting the IWEM software
You can exit the IWEM software by clicking on the | RLE| menu, and choosing
| EXIT . If you forget to save before trying to exit the IWEM software, a dialog box will
ask if you want to save your data before exiting the software.
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IWEM User's Guide Section 5.0
5.5 Tier 2 Evaluation
In a Tier 2 evaluation, IWEM analyzes available site-specific data to develop liner
recommendations that are more tailored to your site conditions than the national,
screening-level Tier 1 evaluations. This section of the User's Guide describes the Tier 2
input and results screens.
The main Tier 2 Input screen group (Figure 5.23) consists of the following screens
and dialog boxes:
• WMUTvpe(16)
• WMU Parameters (17)
• Subsurface Parameters (18)
• Infiltration (19)
• Climate Center List (19a)
• Constituent List (20)
• Enter New Constituent Data (20a)
• Add New Constituent (20b)
• Add New Data Source (20d)
• Constituent Properties (21)
• Toxicity Standards (22)
• Input Summary (23)
After you complete the Tier 2 data inputs, IWEM will begin the Tier 2 analysis.
The Tier 2 Evaluation Run Manager (24) screen is displayed during the Tier 2
analysis. Depending upon the model inputs and the speed of your PC, a Tier 2 analysis
may take anywhere from several minutes to several hours to complete.
The Tier 2 results are then presented on the Summary Results (25) screen. The
Detailed Results screen for the Tier 2 Evaluation varies according to the option you chose
for the infiltration rate. When using an IWEM-generated location-based estimate of
infiltration, the Detailed Results screen for Tier 2 consists of either three screens (for
landfills, surface impoundments, and waste piles) or one screen (for LAUs):
• Results - No Liner (26)
• Results - Single Clay Liner (27)
• Results - Composite Liner (28)
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IWEM User's Guide Section 5.0
When using a user-specified infiltration rate, the Detailed Results screen for
Tier 2 consists of only a single screen:
• User-Defined Liner Results (28)
The overall Tier 2 result is then displayed on the Tier 2 Evaluation Summary (29).
The available options and data displayed on each of these screens and dialog
boxes are explained in the following sections.
5.5.1 Tier 2 Input Screen Group
If you begin with the Tier 1 Evaluation and choose to proceed to the Tier 2
Evaluation with the same selected constituents, then the WMU type, list of waste
constituents, and the expected leachate concentrations specified in Tier 1 are
automatically transferred to Tier 2. These values can also be edited in Tier 2, if desired.
5.5.1.1 Tier 2 Input: Waste Management Unit Type (16)
The first screen of the Tier 2 Input screen group, WMU Type (16), is identical to
the Tier 1 WMU Type screen.
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IWEM User's Guide
Section 5.0
|S Tier 2 Input
- n x:
WMUTyp
'(16)
Select WMUT^e
WMU Parameters (17)
f Surface Impoundment
C* Waste Pile
C" Land Application Unit
Facility Identification Information
_ Southern Industries Landfill
1122 Industrial Ave
• Raleigh
INC
I! 27611
I October 31,1998
Next»
B. Enter descriptive
facility information
Figure 5.23 Tier 2 Input: WMU Type (16).
The features identified in Figure 5.23 are explained in more detail in the following
paragraphs.
A. Choose WMU Type
First, select one of the following choices from the | SELECT\AMJTYPE) option list by
clicking on the appropriate radio button:
• Landfill
• Surface Impoundment
• Waste Pile
• Land Application Unit
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IWEM User's Guide Section 5.0
B. Enter Descriptive Facility Information
In the text boxes located in the lower half of the screen, enter the following
information about the WMU being evaluated:
Facility name
Address of the WMU (street, city, state, zip)
Date of waste constituent analysis
Your name (name of the person performing the liner evaluation)
Any additional identifying information that you would like to include
All information entered in these text boxes will be included on the printed Tier 2
Evaluation Reports (and in the Tier 1 report, if these data were carried over from a
previous Tier 1 analysis).
5.5.1.2 Tier 2 Input: WMU Parameters (17)
The Tier 2 evaluation uses site-specific WMU data to assess potential ground-
water impacts. The WMU parameters are entered on the WMU Parameters (17) screen.
A complete list of all WMU parameters is shown below, however, not all parameters are
applicable for each WMU type. For instance, data on the WMU's operational life is used
only for surface impoundments, waste piles, and LAUs. This parameter is not applicable
to landfills. Some parameters are marked as (required). This means that you must
provide a site-specific value for this parameter. If a parameter is not marked as
(required), IWEM will use a site-specific value if you have it. 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 used in
Tier 1.
WMU Parameters:
Area of the WMU (required)
Distance to well
Depth of WMU (LF only) (required)
Ponding depth (SI only) (required)
Operational life of WMU (WP, SI, and LAU only)
Depth of WMU base below ground surface (LF, WP, and SI only)
Sludge thickness (SI only)
Distance to nearest surface water body (SI only)
Brief explanation for each site-specific value (required)
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Section 5.0
For each type of WMU, the Tier 2 WMU screen looks slightly different, as shown
below in Figures 5.24 through 5.27.
WMU Type (16)
WMU Parameters (17) | Subsurface Parameters (18)
This screen allows you to enter or change land application unit parameters. Justifications for parameters are required.
Parameter
Value I Data Source
150 Default
40 Default
123455 LAD Survey Da
« Previous
Apply Defaults
Nex
A. Enter available
site-specific
values for LAU
Figure 5.24 Tier 2 Input: WMU Parameters (17) for Land Application Units.
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IWEM User's Guide
Section 5.0
WMU Type (16)
WMU Parameters (17) [ Subsurface Parameters (18) |
This screen allows you to enter or change landfill parameters. Justifications for parameters are required.
Log Book
Default
Topo Maps
Default
A. Enter available
site-specific
values for LF
Figure 5.25 Tier 2 Input: WMU Parameters (17) for Landfills.
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IWEM User's Guide
Section 5.0
C. Enter or select
the distance to
the nearest surface
water body
jl Tier 2 Input
WMU Type (16) J WMU Parameters (17) ] Subsurface Parameters (18) ]"
This screen allows you to enter or change surface impoundment parameters. Justifications for parameters are n
Distance to Nearest Surface Water Body (m) Unknown, but less than 2000m (Model uses 360m)
squired.
Value I Data. Source
150 Default
0 Default
.2 Default
1234556 Topo maps
1,6 Initial Estimate
50 Default
« Previous
Apply Defaults
Mext»
A. Enter available
site-specific
values for SI
Figure 5.26 Tier 2 Input: WMU Parameters (17) for Surface Impoundments.
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IWEM User's Guide
Section 5.0
WMUType(16) T WMU Parameters (17) I Subsurface Parameters (18) 1
This screen allows you to enter or change waste pile parameters. Justifications for parameters are required.
Parameter
Value Data Source
150 Default
12345 WP Survey Data
0 Default
20 Default
« Previous
Apply Defaults
A. Enter available
site-specific
values for WP
Figure 5.27 Tier 2 Input: WMU Parameters (17) for Waste Piles.
For all Tier 2 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.
The features identified in Figure 5.24 through 5.27 are explained in more detail in
the following paragraphs.
5-57
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IWEM User's Guide Section 5.0
A. Enter Available Site-Specific Values
Land Application Unit (Figure 5.24)
For LAUs, site-specific values for the following parameters may be entered:
• Area of the LAU (required)
• Distance to nearest well (optional; default = 150 m)
• Operational life of the LAU (optional; default = 40 yrs)
Landfill (Figure 5.25)
For LFs, site-specific values for the following parameters may be entered:
• Area of the LF (required)
• Distance to nearest well (optional; default = 150m)
• Depth of the LF (required)
• Depth of the LF base below ground surface (optional; default = Om)
Surface Impoundment (Figure 5.26)
For Sis, site-specific values for the following parameters may be entered:
Area of the SI (required)
Distance to nearest well (optional; default = 150m)
Ponding depth (required)
Operational life of the SI (optional; default = 50 yrs)
Depth of SI base below ground surface (optional; default = 0 m)
Sludge thickness (optional; default = 0.2 m)
Waste Pile (Figure 5.27)
For WPs, site-specific values for the following parameters may be entered:
• Area of the WP (required)
• Distance to nearest well (optional; default = 150m)
• Operational life of the WP (optional; default = 20 yrs)
• Depth of the WP base below ground surface (optional; default = Om)
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IWEM User's Guide Section 5.0
B. Enter Data Source
For all Tier 2 input parameters for which you enter site-specific values, remember
to type in a brief explanation of this value. This information is required and will be
included in the printed report.
C. Enter or Select the Distance to the Nearest Surface Water Body
For a SI, 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. If you do not know the exact distance to the
nearest surface water body, select "unknown" from the drop-down list by clicking on the
drop-down list control _LJ to select an approximate distance (i.e., unknown (model uses
360 m); unknown, but less than 2,000 m; unknown, but greater than 2,000 m).
5.5.1.3 Tier 2 Input: Subsurface Parameters (18)
This screen is where you enter site-specific data that describes the subsurface
environment at your site.
The subsurface parameters used in IWEM are listed below. You must select the
type of subsurface environment at your site from the supplied list. Section 6.2.3.2
provides more information on the subsurface environments. If you have no
hydrogeological information for your site, then "unknown" is an available choice. If your
list of waste constituents includes any metals, you must also provide a value for the
ambient ground-water pH. For the other subsurface parameters, you can provide a site-
specific value if you have it, but IWEM will use a default value or distribution of values
if you do not have this data.
Subsurface Parameters:
• Subsurface environment (required, although "unknown" is an available
choice)
Depth to water table
Aquifer thickness
Regional hydraulic gradient
Aquifer hydraulic conductivity
Ground-water pH (required only if a metal is included in the waste
constituents)
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IWEM User's Guide
Section 5.0
I liSASS^^^^ffE^^ff^ki^'- ^^i-:---:-'..:: " • ™ ""' .• *
-lolxj
T vVMU Parameters (1 ?J T Subsurface Parameters (1 8) ] infiltration (1 9)
This screen allows you to enter or change the subsurface parameters.
You MUST select a Subsurface Environment tf you select 'unknown' then the default values will be used for si! parameters, in addition, you MAY enter values for one or
more hydrogeofogjc parameter(s). Dais, sources are required,
Selectthe Subsurface Environment: •*•]
Pammster Allu-viol & Flood Rein without Overbook Deposits
Tit! and Till over Oulwash
3) r2iL ",^^''"i;r\^;"'!-^'l'i Unconsolf dated and Semiconsoiidated Shallow Aquifers
Coa;tel Beeches
"™^T:;i; i^v11"': , <;L ?< ^'•}^'-"i'"'"f t-'% Solution Limestone 4
iJnlriown
^>'lJ|^^"^>'^''
^^^•^^.
« Previous
*
1 __
Mext>>
A. Select subsurface
environment
Figure 5.28 Tier 2 Input: Subsurface Parameters (18)
Selecting Subsurface Environment.
The features identified in Figure 5.28 are explained in more detail in the following
paragraph.
A. Select Subsurface Environment
IWEM includes twelve different types of subsurface environments that represent
different hydrogeological settings. 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 twelve known environments. You must select one of
the available subsurface environments. Figure 5.29 presents an example of what this
screen will look like if you choose one of the available subsurface environments (the
screen appears only slightly different if you set the subsurface environment to
"unknown").
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IWEM User's Guide
Section 5.0
Subsurface Parameters (1 8)
Infiltration (1 9)
This screen allows you to enter or change the subsurface parameters,
You MUST select ® Subsurtace Environment If you select 'unknown' then the default values wilt be used for al! parameters. In addition, you MAY enter values for one or
more hydrogeologic parameter(s). Data sources are required
Selectthe Subsurface Environment; jSand and Gravel j»j
j Default
Value | Data Source
.Distribution Monte Carlo [see IWEM TBD 4.2.3.1]
Distribution Monte Carlo [see IWEM TBD 4.2.3.1]
Distribution Monte Carlo [see IWEM TBD 4.2.3.1]
Distribution Monte Carlo [see IWEM TBD 4.2.3.1]
Distribution A Monte Carlo [see IWEM TBD 4.2.3.1]
Figure 5.29 Tier 2 Input: Subsurface Parameters (18) -
Entering Values of Subsurface Parameters.
The features identified in Figure 5.29 are explained in more detail in the following
paragraphs.
A. Enter Available Site-Specific Values
If you select one of the twelve subsurface environments, then screen 18's
appearance will be similar to that shown in Figure 5.29. You may enter values for any
subsurface parameters for which you have site-specific data. However, you may enter
data for only some (but not all) of the parameters and continue with the Tier 2 analysis.
In this case, a distribution of parameter values that corresponds to the specified
subsurface environment will be used to generate values for any parameter for which you
do not enter a site-specific value. The word "Distribution" displayed in the default value
column and the phrase "Monte Carlo [see IWEM TBD 4.2.3.1]" in the data source
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IWEM User's Guide Section 5.0
column indicate that IWEM will randomly select values for this parameter from the
appropriate distribution during the Tier 2 analysis process. The distributions reflect the
range of values that each parameter can have.
If you do not know the type of subsurface environment beneath your WMU, then
you can select the "unknown" subsurface environment. For the unknown subsurface
environment, a default value (the one displayed in the default value column) will be used
for any input parameter for which you do not enter a site-specific value; that is, 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 twelve subsurface environments. This value is representative
of a national average. You may enter values for subsurface parameters that you have site-
specific data for. However, if you are lacking data for one or more of the requested
parameters for your site, you can still perform a Tier 2 analysis. In this case, the default
(displayed) value will be used. The displayed value in the data source column and the
phrase "Default [see IWEM TBD 4.2.3.1]" in the data source column indicate that IWEM
will use the displayed default value for this input parameter in the Tier 2 analysis.
The subsurface parameters for which you can enter site-specific values are:
Ground-water pH
Depth to water table
Aquifer hydraulic conductivity
Regional hydraulic gradient
Aquifer thickness
A site-specific value for ground-water pH is only required if the modeled waste
constituents include metals; this parameter is not needed as a user-input for modeling
organic constituents.
B. View or Edit Data Source for Each Value
If you select one of the twelve subsurface environments, then for any Tier 2 input
parameter that you enter as a site-specific value, you must document the data source or
explain the value used. IWEM provides a default data source for all optional data. The
default data source is "Monte Carlo [see IWEM TBD 4.2.3.1]" as a reminder that a
distribution of values (rather than a single, constant value) is being used for this
parameter. All data sources or explanations for default or user-specified data are included
in the printed Tier 2 report.
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IWEM User's Guide Section 5.0
If you select the unknown subsurface environment, then for any Tier 2 input
parameter that you enter as a site-specific value, you must document the data source or
explain the value used. IWEM provides a data source for all default data. For the
"unknown" subsurface environment, the default data source is "Default [see IWEM TBD
4.2.3.1]" as a reminder that a single, constant value (rather than a distribution of values)
The information provided on screens 17 and 18 completely describes the WMU
setting as required by IWEM. When you click NEXT| on screen 18, IWEM will
check your inputs to evaluate whether the setting you have described is physically
possible and consistent with the EPACMTP model.
IWEM verifies that:
• the bottom of LFs and WPs are above the water table; and
• the elevation of ponded water in a SI is higher than the water table
elevation.
If you do not specify the depth to ground water, IWEM will postpone this evaluation
until screen 19 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 Tier 3 analysis. Consult Section
2.3 of this User's Guide, or the IWEM Technical Background Document (U.S. EPA,
2002c) for more information on the assumptions built into the EPACMTP model
which may make it unsuitable for a particular site.
is being used for this parameter. All data sources or explanations for default or
user-specified data are included in the printed Tier 2 report.
5.5.1.4 Tier 2 Input: Infiltration (19)
On screen 19 (Figure 5.30), you enter or select the infiltration rate that IWEM will
use in modeling your site. The first selection is whether you have site-specific infiltration
data, or wish to use IWEM default data if you do not have site-specific data.
In IWEM, infiltration refers to the liquid (leachate) that infiltrates to the
subsurface directly below a WMU; recharge refers to the natural precipitation that
infiltrates to the subsurface outside the footprint of the WMU.
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IWEM User's Guide
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Choose one of the following options for specifying infiltration rate:
YES, I HAVE 9iE-spEanc INFILTRATION | (i.e., a measured, modeled, or calculated
value);
No, I DONOTHAVE9TE-spEanclNnLTRATiON| (the model will estimate values for
you based on the selected soil type (or waste type permeability, for WPs) and
geographic location of the WMU site).
MTier 2 Input
T Subsurface Parameters (18)
ssur
Do you have site-specific infiltration?
j~ Yes, I have Site-Specific Infiltration, Results will be reported
for your user-defined liner
Soil Data
Please select a soil type
Coat;e-gtained ;oil (sandy loom)
Medium-grained soil (silt loam)
Fine-grained soil (silty clay loarn)
Unknown soil tvoe
Infiltration (19)
ConstitusntListpO)
No, I do not have Site-Specific Infiltration. Res
reported for the_defoult tmar tygefjs) _
Local Climate Data
Nearest Climate Center
Selected city
Infiltration Rates (m/yr)
View Cities List
Please select a city.
No Liner
±LJ
| Single Liner [ Composite Liner
1
•
>
Recharge Rate (m/yr)
All Scenarios
ults will be'
« Previous
Mext»
Figure 5.30 Tier 2 Input: Infiltration (19) - Initial Appearance.
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Section 5.0
At its initial appearance (with the | No, I DONOTHAVE9lE-SPEaFlClNFlL-mATlON| radio
button selected by default), screen 19 will generally appear like Figure 5.30 (although this
screen can be slightly different depending upon the selected WMU type).
it Tier 2 Input
:>,', _ | o 1 X |
WMUF-ooineteisn;', | Subsurface Parameters (1 8) ] Infiltration (1 9) f Constituent List (20)
Do you have site-specific infiltration?
r Yes, 1 have Site-Specific Infiltration. Results will be reported ^ No, 1 do not have Site-Specific Infiltration, Results will be
for your user-defined liner, reported for the default liner Vpe(s),
- Soil Data - - - .
Please select a soil type:
Local Climate Data
Nearest Climate Center
Selected city
• • Infiltration Rates (m/yr)
No Liner
0.326
(Coarse-grained soil (sandy loam)
•Medium-drained soil ism loarni ^••1
Fine-grained soil (silty clay loom)
Unknown soil type
View Cities Ust
Greensboro NC
Recharge Rate (m/yr)
All Scenarios
0326
« £revious
Next»
Figure 5.31 Tier 2 Input: Infiltration (19) - Land Application Unit.
If you do not have a site-specific value for infiltration, once you have selected a
soil type (or waste type permeability, for waste piles) and climate center, screen 19 will
appear like one of the screens presented in Figures 5.31 through 5.34 depending on the
WMU type you have selected.
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IWEM User's Guide
Section 5.0
j| Tier 2 Input
I Subsurface Parameters (18) | Infiltration (19) | Constituent List (20)
Do you have site-specific infiltration?
»-. Yes. I have Site-Specific Infiltration, Results will be reported ,~ No, I do not have Site-Specific Infiltration, Results will be
for your user-defined liner.
Soil Data
reported for the default liner type(s).
Please select a soil type:
Local Climate Data
Nearest Climate Center
Selected city
Infiltration Rates (m/yr)
Coarse-grained soil (sandy loam)
Fine-grained soil (silty clay loam)
Unknown soil type
View Cities List
Greensboro
NC
, Recharge Rate (m/yr)
No Liner
0326
BJ
1 Single Liner
0.036
1 Composite Liner
Monte Carlo
±
All Scenarios
0.326
« Erevious
Next»
Figure 5.32 Tier 2 Input: Infiltration (19) - Landfill.
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Section 5.0
it Tier 2 Input
VAC«P«!,,affie!9.s(i;'j
-a' .Jfljxj
1 Subsurface Parameters (1 8) | Infiltration (1 9J | Constituent List (20)
Do you have site-specific infiltration?
* Yes, 1 have Site-Specific Infiltration, Results will be reported ,» No, 1 do not have Site-Specific Infiltration. Results will be
for your user-defined liner. reported for the default liner typefs).
Please select a soil type:
r Local Climate Data
Nearest Climate Center
Selected ciV
: Infiltration Rates (m/yr)
Coarse-grained soil (sandy loam) !
Fine-grained soil (silty clay loam) I
Unknown soil type
View Cities List
Greensboro NC \
, Recharge Rate (m/yr)
| No Liner | Single Liner | Composite Liner All Scenarios 1
Monte Carlo Monte Carlo Monte Carlo 0 326
__ . ^
i
« Previous
Next»
Figure 5.33 Tier 2 Input: Infiltration (19) - Surface Impoundment.
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Section 5.0
gfl Tier 2 Input
' - . y Subsurface Parameters (18) J Infiltration (1 9) "\ Constituent List (20)
Do you have srte-speerfic infiltration'
f. Yes, I have Site-Specific Infiltration. Results will be reported a iNo, I do not have Site-Specific Infiltration Results will be j
for your user-defined liner, ^reported for the default liner type(s). j
- Soil Data
i PlfiaSB sfitart n snii tvrm- ICoarsejrained so l(saridy loam)
IS^»l^^ffl$Iii1lilSI*l!filIIldlllD55W^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^™
I Fine-grained soil(silty clay loam)
1 Unknown soil type
-Waste Tvpe- -. Local Climate Data
• Please select a permeability Low permeability
i corresponding to waste type: Medium permeability vfa , . , View Cities List
i H.qhper^^ty Oimate Center
Infiltration Rates (m/yr)
No liner | Single Liner | Compos
Monte Carlo Monte Carlo Monte Ci.
LiLJ
«Prewous
• Recharge Rate (m/yr)
te Liner All Scenarios \
rlo 0 326
>
Next»
F. Select waste
type according
to permeability
Figure 5.34 Tier 2 Input: Infiltration (19) - Waste Pile.
The features identified in Figures 5.30 through 5.34 are explained in more detail
in the following paragraphs.
A. Specify Infiltration Data Option
Displayed at the top of screen 19 is the following question:
"Do you have a site-specific value for infiltration rate?"
Select one of the two available options:
YES, I HAVE A9TE-SPEQFIC INFILTRATION RATE|, or
NO, I DO NOT HAVE A9TE-SPEQFIC INFILTRATION RATE |
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IWEM User's Guide Section 5.0
If you choose | No , the Tier 2 evaluation will be performed for the default liner
type(s). There are three liner types for landfills, surface impoundments, and waste piles
(no liner, single clay liner, and composite liner). IWEM will evaluate only the no-liner
scenario for land application units because engineered liners are not usually used at this
type of facility.
If you choose | YES| , the Infiltration Screen will appear as in Figure 5.36 and the
Tier 2 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.
The final result of a Tier 2 analysis is a recommended minimum liner design that
is protective for all the selected constituents in your waste. When you specify a site-
specific infiltration rate, IWEM will evaluate a "user-defined liner" scenario for
protectiveness; otherwise, IWEM will evaluate all appropriate default liner scenarios.
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, the Tier 2 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 Tier 2 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 4.2.3.2 of the IWEM Technical
Background Document (U.S. EPA, 2002c).
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IWEM User's Guide Section 5.0
C. Choose Climate Center
For unlined units, except Sis, and for single clay-lined LFs and WPs, 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 6.4 of Section 6.2.3.3 of this document. You should, however, verify that the
overall climate conditions at the selected climate station are representative of your site.
Section 4.2.2 of the IWEM Technical Background Document (U.S. EPA, 2002c) provides
a detailed discussion of how the infiltration rates were developed. To choose a climate
center, click on the | VlEWQTlESLJST button. The dialog box shown in Figure 5.35 will
appear.
D. Infiltration Rate(s)
If you do not have a site-specific infiltration rate (see Figures 5.31 through 5.34),
once you have selected a soil type and the nearest climate center, the model 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 LAUs). The resulting value(s) are listed in the table at the bottom left of the
infiltration screen.
E. Recharge Rate
Once you have selected a soil type and the appropriate climate center, the model
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.
F. Select Waste Type According to Permeability
For a WP, 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 10~2 centimeters per second [cm/sec]), medium (4.1 x
10~3 cm/sec), and low (5.0 x 10~5 cm/sec). These values are representative of wastes
commonly disposed in WPs.
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To choose a climate center to provide default recharge and infiltration data, click
on the VlEWQlESUST button on the Infiltration (19) screen. The dialog box shown below
in Figure 5.35 will then be displayed.
C. Select nearest
climate center
Albuquerque
Annette
Astoria
Atlanta
Augusta
Bang or
Bethel
Bismarck
Boise
Boston
iBridcrep
BIBHHI1
NM
AK
OR
GA
ME
ME
AK
ND
ID
MA
ort CT
B. Slide down
to scroll
through list
-In!
4
X
""""""""
Brownsville TX
Burlington VT
Caribou ME
Cedar City UT
Central Park NY
d
You selected Bridgeport CT
Cancel
<5" Sort by €%
r
D. Verify
selected
climate center
A. Select
sort order
E. Enter selected
climate center and
return to
Infiltration (19) screer
Figure 5.35 Tier 2 Input: Climate Center List (19a).
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IWEM User's Guide Section 5.0
The features identified in Figure 5.35 are explained in more detail in the following
paragraphs.
A. Select Sort Order
You can sort the climate centers alphabetically by city or by state by choosing one
of the SORT BY options.
B. 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.
C. Select Nearest Climate Center
Select a climate center by using the | ARRCW| keys to highlight an entry, or by a
single click on the entry with your mouse.
D. Verify Selected Climate Center
You can verify that the correct climate center is selected by looking at the city
name printed at the bottom of this dialog box.
E. Enter Selected Climate Center and Return to Infiltration (19) screen
Clicking on the OK| button or double-clicking on the highlighted entry will enter
your selection and return you to the Infiltration (19) screen.
If you choose the YES, I HAVE STE-SPECIFIC INFILTRATION option at the top of the
Infiltration (19) screen, then this screen will appear as shown in Figure 5.36.
-------
IWEM User's Guide
Section 5.0
r^ Tier 2 Input
' ' ' I
?$:;^ JflJ^J
Subsurface Parameters (18) J Infiltration (1 9) f Constituent List (20)
Do you have site-specific infiltration?
ff Yes, 1 have Site-Specific Infiltration, Results will be reported ^ No, 1 do not have Site-Specific Infiltration. Results will be
for your user-defined liner. reported for the default liner type(s),
r Soil Data
Pief.ee color* nenillupo- "-°a
ps
Fine
Unk
Srte-Specific Infiltration (m/yr)
1 Parameter ]
rse-gramed soil(sandy loam)
lum-aramed soilisi t loam) ^H 1
-grained soil(silty clay loam)
nown soil type
Value
Data Source |
0.12 Test Value
A
•{iiilMliF^?r;'"*,r'''r «•••
Local Climate Data
Nearest Climate Center
Vie*
1 Selected city Greerisboio
« Previous
, Recharge Rate (m/yr)
i Cities List AII_Scenarios |
NC
Next»
A. Enter site-specific
infiltration rate
and data source
Figure 5.36 Tier 2 Input: Infiltration (19) - Site Specific Infiltration.
The features identified in Figure 5.36 are explained in more detail in the following
paragraphs.
A. Enter Site-Specific Infiltration Rate and Data Source
Enter your site-specific infiltration rate and provide a brief explanation of the data
source for your value in the DATASOURCE cell. Both the value and your explanation will
be included in the printed Tier 2 report.
5.5.1.5 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
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IWEM User's Guide Section 5.0
Tier 2 Monte Carlo process will represent physically realistic WMU settings. These
constraints are:
1. The base of a LF or WP must be above the water table,
or,
The elevation of ponded water in a SI must be higher than the water table
elevation; and
2. Infiltration- and recharge-induced mounding of the water table cannot rise
above the ground surface.
If either one of these constraints is violated, the model 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 the simulation
model might encounter a scenario where a constraint is frequently violated, and the model
is unable to complete the Monte Carlo simulation process.
IWEM screens your Tier 2 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. 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 17 through
19, the screener will determine the magnitude of water table mounding (that is, IWEM
will evaluate the constraints on hydraulic connections between the WMU and the water
table). If the screening is successful, IWEM will take you to screen 20, otherwise a
message box will alert you to the most violated constraint and suggest potential remedies.
If all proposed remedies are inconsistent with site conditions, then IWEM is not
appropriate for your site and a Tier 3 analysis should be considered.
If you do not provide site-specific values for all possible Tier 2 inputs, the
screener will generate values for the missing input parameters according to their
appropriate distributions, and then evaluate the constraints. The screening process
usually takes ten or twenty seconds to complete, but can take up to a minute or two. A
progress bar, like the one displayed below, is updated during the screening process.
Now checking the feasibility of your input values...
Please Wait...
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IWEM User's Guide Section 5.0
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 like the one
shown below which asks if you want to continue. If you click | OK|, IWEM will continue
with the input parameters you provided.
IWEM has determined that the aquifer system you have described is not likely to support a
drinking water well,
If this is inconsistent with your site conditionSj you may wish to increase the value of aquifer
thickness or aquifer hydraulic conductivity,If either of these changes are inappropriate for your
site, you may still proceed with the analysis.
Do you wish to proceed with this analysis?
Yes I No
5.5.1.6 Tier 2 Input: Constituent List (20)
This is where you select the constituents that are present in the waste, and enter
their leachate concentration. You can select constituents in several ways. You can:
• Search by Constituent Name or CAS Number, or
• Scroll through the list of IWEM constituents, using display and sort
options.
If you performed a Tier 2 evaluation immediately after a Tier 1 evaluation, the
waste constituents selected in Tier 1 are automatically transferred to Tier 2 and the Tier 1
leachate concentrations are also imported. If you are starting a Tier 2 evaluation and need
to enter waste constituents, follow the steps described here.
The Constituent List (20) screen for Tier 2 is nearly identical to the Tier 1
Constituent List (7) screen, and the options and controls on this screen work exactly the
same as the ones on the Screen 7. You can choose to include in your Tier 2 analysis any
of the 206 organic constituents and 20 metal constituents included in the IWEM database
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IWEM User's Guide
Section 5.0
(see Appendix A). However, unlike Tier 1, in Tier 2 you can also add constituents to the
IWEM list.
jStuemf D^hig blighted R choosg ord£r ^^ONSTITUENTSI
byjfmeor [SELECTED CONSTITUENTS) for |ALL CONSTITUENTS] AU CONSTITUENTS)
LAJ>f? list list
IJ8 Tier 2 Input
i..
mstituent Name 1
CAS Number;!'
All Constituents
_ '^ ,
] Intiltra
83-32-9 Acenaphthene *J
75-07-0 Acetaldehyde [Ethenal] Zj
67-64-1 Acetone (2-propsnone)
75-05-8 Acetonitrile (methyl cyanide) i
1 07-02-8 Acrolem
1
79-06-1 Acrylemide
309-00-2 Aldnn
1 07-1 8-WMIyl alcohol
62-53-3 / .niline (benzeneomine) w\
« Previous 1
C. Select
constituents
to be included
in Tier 2 analysis
on (19) 1 Constitue t List (20) | Constituent Propertii
(•* Constituent Name
U-i
*d
Ad
r CAS Number
Type ot Consttoent
<• All constituents
(~ Organics
<~ Metals
Selected Constituents
CAS Constittsnt Name Leachate
Nymber Concentration
(mg/L)
_^ 107-13-1 Aoylomtnle 4
d New Cor»^i|yent
G, Remove highlighted
constituent from
SELECTED CONSTITUENTS]
ist
I. Add new E, List of
constituent constitue
in Tier 2
I 01 (
t
1
lalxj
3(21)
sxt»
F. Enter
its expected
uded leachate
analysis concentration(s)
Figure 5.37 Tier 2 Input: Constituent List (20).
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The features identified in Figure 5.37 are explained in more detail in the following
paragraphs.
A. Filter ALL CONSTITUENTS | List
You can choose to display only organic constituents, only metals, or a combined
list of all constituents by clicking one of the radio buttons under TYPE OF CONSTITUENT .
B. Choose Sorting Order for ALL CONSTITUENTS | List
You can determine whether the constituents are sorted by name or by CAS
number by clicking one of the SORT BY radio buttons.
C. Select Constituents to be Included in Tier 2 Analysis
To move through the list of waste constituents:
1) Use the scroll bar at the right of the display window
2) Use the ARROW keys on the keyboard (once one
constituent in the list is selected)
3) Type in the constituent name or CAS number in the
I SEARCH BY! box
You can select constituents by using one of these methods:
• To add an individual constituent, select that constituent by clicking on its
name.
• To add 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.
• To add multiple constituents that are not in contiguous order, click on the first
waste constituent, and then hold down the CTRL key while selecting
additional constituents using the mouse.
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Once your selection is complete, use the ADD button (described below) to
transfer all the highlighted constituents to your list.
D. Add Highlighted Constituent^) to SELECTED CONSTITUENTS List
Once the appropriate constituents are highlighted in the list (on the left of the
screen), you can click the ADD ,2J button in the center of the screen to transfer it to your
list of leachate constituents (on the right side of the screen). Note that a waste constituent
can also be added directly to your list by double-clicking on it in the list on the left.
E. List of Constituents to be Included in Tier 2 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 automatically added to the Tier 2 evaluation. You can modify
constituent properties and toxicity standards of the daughter product(s) in the upcoming
screens.
F. Enter Expected Leachate Concentrations
For each waste constituent in the | SELECTED CONSTITUENTS list, you must enter your
expected leachate concentration in mg/L. This value cannot exceed 1,000 mg/L. Consult
Chapter 2-Characterizing Waste in the Guide (U.S. EPA, 2002d) for analytical
procedures that can be used to determine expected leachate concentrations for waste
constituents. 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.
The IWEM software will display a warning message similar to the one shown
below if you enter an expected leachate concentration that exceeds the solubility of that
constituent, as cited in the IWEM database. If you accidentally entered the wrong value,
click the YES button and correct the expected leachate concentration on the Leachate
Concentration (8) screen. 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.
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The leachate concentration specified for Acenaphthene is greater than the cited solubility value in
the database of 4,24 mg/l,
Do you want to change the leachate concentration ?
Yes
No
The Tier 2 Evaluation cannot be performed until the expected leachate
concentration is entered for each selected waste constituent.
G. Remove Highlighted Constituent from SELECTED CONSTITUENTS |Lisf
Analogous to the ADD button, you can click the | REMOVE _ffl button to delete a
highlighted constituent from the your list of selected constituents.
H. Search for Constituents by Name or CAS #
Type the name or the CAS number in the | SEARCH BY window to select a particular
constituent on the IWEM list. As soon as you have typed in enough information to
identify the constituent, it will be highlighted in the constituent window on the left of the
screen. 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.
/. Add New Constituent
To add a new waste constituent, click on the ADD NEW CONSTITUENT | button at the
bottom of the Constituent List. The message box shown below in Figure 5.38 will
appear:
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IWEM User's Guide
Section 5.0
A. Enter B. Enter
CAS number constituent name
', ,*™ • , ™lv"(, "JAAA" ,1 *'''*>' ^"'''H if'*.' '
. ] Infiltration (1 9) J
Search By
Ce
Sort
nstituent Name:! ft QO
CAS Number!"
-G*
9!R!KH!i^^^^^^H|4|Enter New
83-32-9 Acenaphthene
75-07-0 Acetaldehyde [Ethanal] rj^g Number
67-64-1 Acetone (2-propanone)
75-05-8 Acetonitrile (methyl cyanid
1
nstituent List (2
iy
istityent Name
3 Number
I
«
Jnjx
0) | Constituent Properties (21)
• Type of Constituent
f* All constituents
<~ Organics
r Metals
x|
I
ts
Leadi ate
Concentration
(mg/L)
C. Click to enter
new constituent data
Figure 5.38 Tier 2 Input: Enter New Constituent Data (20a).
The features identified in Figure 5.38 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.
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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 5.39) will appear.
fj Add New Constituent (20b)
—
Property
3*:^\' -i
vr^W:
»n.
,5":;
-uy;V;; -_l.nj..XJ
Value
9 C 1:8 7
test <
t^i^^lAi^.
»
Property
fAf**^.1",! n£ ^t '"™)I™M« * ft '
"' ' '"^.'" '"
^•r^ ^f'*2-'"*'
• Add
Value
Constituent List 120)
Data Source
3-4 LdrnbtrdgeSott Corporation 2001 ChetnFinder com
~ull Refefence £ *•
New Source
NO REFERENCE AVAILABLE
CambrtdgeSoft Corporation 200 ChefTtFihriyt ci rn database and internet s
USEPA 1993a Envirorf mental F-ttn t , n t-ttit ft r T \ r "*-*- cals Under
JSEPA 1998d Evaluation of ireF I'priiah -rrnnuger t E» yl Methanes
JSEPA 1986a Addendum to HIP i-nr-lth/- H "mcrtCr trtforTetrach
Data Source
Cancel
A. Enter available R Caia^
data for constituent o.^eiec
properties existing
tor each
i arch ing.
Consideration
-54G-R-9 7-036
u If on ate
iroethylene ^
t new or
data source
input value
Figure 5.39 Tier 2 Input: New Constituent Data (20b).
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The features identified in Figure 5.39 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" later on, in screen 22.
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 Levels)
HBN (Non-carcinogenic-Ingestion)
HBN (Carcinogenic-Ingestion)
HBN (Non-carcinogenic-Inhalation)
HBN (Carcinogenic-Inhalation)
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. However, for each constituent at least one
non-zero RGC value must be entered (either an MCL, or an HBN). If you enter an HBN
RGC, you must also enter its corresponding toxicity value (listed in the column next to
each HBN). IWEM assumes a 30-year exposure duration for cancer HBNs and 7-year
exposure duration for non-cancer HBNs.
B. Select Type of Data Source for Each Input Value
For each constituent property value that you enter, you must specify the source of
the data. Clicking in the | DATA SOURCE field after entering your data will display the drop-
down list control —J. Click on this control to reveal the drop-down list shown in Figure
5.39. You can select from the current list of references in the IWEM database, or you can
choose NEWSOURCE to enter a bibliographic reference that is not included in the IWEM
database (see Figure 5.40).
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C. Add New Constituent to the Database and Return to the Constituent List (20)
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 Tier 2 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.
Enter full bibliographic citation here
LLLJ
Add New Source
Cancel
C. Add data source
and tjo back to
D. Cancel the creation
of a new data source
and go back to
Add New Constituent (20b)
screen
Figure 5.40 Tier 2 Input: Add New Data Source (20d).
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The features identified in Figure 5.40 are explained in more detail in the following
paragraphs.
A. Enter Brief Bibliographic Citation
If you choose | NBA/SOURCE on dialog box 20b, the dialog box shown in Figure
5.40 will appear. 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.
B. 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.
C. Add Data Source and Go Back to Add New Constituent (20b) screen
Click the ADD NBA/SOURCE | button to enter this citation into the IWEM database
and return to dialog box 20b.
D. Cancel and Go Back to Add New Constituent (20b) screen
Check the | CANCEL button if you do not wish to use the new bibliographic
citation. This will return you to dialog box 20b.
5.5.1.7 Tier 2 Input: Constituent Properties (21)
On this screen, 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 Tier 2 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.
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IH Tier 2 Input
| Constituent List (20
Select a constituent from the first list below. Properties of tt
properties of a daughter product select it from the second
Waste Constituents: |107-13-1 Acrylonitnle
Daughter products; j
Default Properties of 107-13-1 Acrylanitrile
1st
J Constituent Properties (21) \ Reference GW Cone, (22)
lected constituent will be displayed in the grids. To see the
"3
User Supplied Property Values
Proper^
Koc (L/kg)
Rate
Add-cataiyzee
hydrolysis - Ka
(/moi/yr)
li
Value [Source^
815E-01 lUSEPA 1993a
V jjue j Source
5.00E + 02 USEP.A 199
Property | Value I Source
LHJ
Figure 5.41 Tier 2 Input: Constituent Properties (21).
The features identified in Figure 5.41 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—J at the right edge of the | WASTE CONSTITUENTS | listbox. To view the constituent
properties for a constituent that is produced by hydrolysis of one of your entered
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constituents, click on the drop-down list control -=J at the right edge of the DAUGHTER
PRODUCTS listbox. If the DAUGHTER PRODUCTS box is blank, it means that the currently
displayed waste constituent has no hydrolysis daughter products. Then use the mouse or
the | ARRCW| keys to scroll through the list of constituents until the desired constituent is
highlighted. Left click on the mouse or hit the ENTER key to make your selection.
B. Default Values
The constituent properties and their default values for the selected waste
constituent are listed in the table on the left side of the screen.
C. Data Sources for Default Values
The data source for each default parameter value of the selected waste constituent
is listed in the "Data Source" field.
D. Enter Site-Specific or Updated Values
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.
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
4.2.4.1 and 4.2.4.3 of the IWEM Technical Background Document (U.S. EPA, 2002c).
E. Enter Data Source
For each Tier 2 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.
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Once your list of waste constituents and expected leachate concentrations is
complete, click on the | NEXT| button to specify RGC values to be used in the Tier 2
evaluation.
5.5.1.8 Tier 2 Input: Reference Ground-Water Concentrations (22)
In screen 22, you select which RGC is to be used to evaluate each waste
constituent in the Tier 2 analysis. You can select RGCs (MCLs and HBNs) that are in the
IWEM database, or you can supply a user-defined RGC. The following options are
available:
• Maximum Contaminant Level (MCL)
• Health-Based Number (HBN)
• User-defined standard (this can be any value and is generally determined by
your state regulatory authority)
• Compare to all available standards
The features identified in Figure 5.42 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.
B. Select Standard(s) to Apply
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. Using the radio buttons,
click on the appropriate standard to use in your Tier 2 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 C and D, below). 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 Tier 2 liner recommendation.
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Constituent Properties gl) | Reference GW Cone. (22) f Input Summary (23) 1
ilect a constituent from the grid, then the desired standard from the list Click the "Apply Standards" button to save each selector
Related
Constituents
Constituent
Standard
Parent 107-13-1 Aoylonitnle
Daughter 79-06-1 Aciylamide
Daughter 79-10-7 Acrylic acid [propenoic acid]
HBN - Ingestion, Cancer
HBN - Ingestion, Cancer
HBN - Ingestion, NonCancet
Standards for 79-10-? Ar.rylit: acid [proponoic acid]
Reference Ground-water
Concentration (mg/L)
15
Select Standard
r W'-.i
r • •
f HBN - Inhalation, Non-Cancer
r ;< . ' i •
f* HBN - Ingestion. Non-Cancer
r User-Defined
Compare to all available standards
lejgcljhejjejirejjstanj^^
Exposure
Duration (yr)
12
T
Justification
T
« Previous
Apply Standard(s)
E. Apply selected
standard) s) to
selected constituent
C. View default
values or enter
user-defined value
Figure 5.42 Tier 2 Input: Reference Ground-Water Concentrations (22).
C. View Default Values or Enter User-Defined Value
These textboxes display the RGC values in the IWEM database; and in the case of
the user-defined RGC, this is where you enter the appropriate RGC value and its
associated exposure duration. In the IWEM model, the exposure duration corresponds to
the time interval over which the average ground-water concentration is calculated.
Consult with the appropriate state regulatory agency for additional guidance on entering
your own RGC value and exposure duration.
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IWEM User's Guide Section 5.0
D. Enter Data Source for User-Defined Value
If you enter a user-specified RGC for any constituent, be sure to provide a brief
explanation of this value in the JUSTIFICATION textbox.
E. 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. After you have done so, your
selection will be displayed in the | STANDARD | column in the table at the top of the screen.
5.5.1.9 Tier 2 Input: Input Summary (23)
This screen displays a summary of the input data for your Tier 2 analysis. You
cannot enter or edit data on the Input Summary screen; rather, its purpose is to
consolidate into one place all the data you have already entered for the Tier 2 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 screen on the Tier 2 Input Screen.
The input summary screen has three sections containing data on: 1) constituent
properties; 2) source and unsaturated zone; and 3) saturated zone. Each section has a
scroll bar which can be used to view information that does not fit on the screen.
The features identified in Figure 5.43 are explained in more detail in the following
paragraphs.
A. Identification of Constituent as Either a Parent or a Toxic Daughter
The first section contains a table of the selected waste constituents, listing their
CAS number, name, expected leachate concentration, 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. Summary of Constituent Properties
For your reference, the constituent-specific properties for each waste constituent
in the Tier 2 analysis are displayed in the table at the top of the screen.
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C. Verify Tier 2 Input Values
The bottom section of this screen consists of two tables that present the selected
values for the WMU and subsurface parameters. To the left, the selected values for the
WMU (source) and unsaturated zone parameters are displayed. To the right, the selected
values for the saturated zone parameters are listed. Note that each table has a scroll bar
on the right-hand side which can be used to view information which does not fit on the
screen.
B. Summary of
constituent properties
Re
arencsGWConc (22)
Input Summary (23)
Consttuent Properties
Related
Constituents
CAS
Constituent
Name
Leachsta
CoRcentration
(mg/L)
Toxid^
Standard
RGC
Log(KocJ
(Ukg)
Ka
(/mo!/y!r)
Kn (/yr)
Kb
f/mo!/vf)
Kd £L/kg)
CX/sral! Decay
Coefficient (/yr|
Parent. 107-13-1 Acrylonitrile
Daughter 79-11>? Acrylic aad
[pfopenosc acid]
01358 HBN-
Ingestion
Area (m "2
Depth of t
WML de
Depsh to
oil type1
rid lira!! cm
recharge
±1
sse oi !he LF below ground surface (m)
|: h (mj [requires site specific value]
tenable (m)
SILT LOAM
No Lillet 3256
Single Liner 0362
Composite Liner Monte Carlo
Rate 0 3256
12345 jjAqutertticMessfm)
0 Regional hydraulic gradient
6 S Aqu ter bydraui c conductivity (m/yr)
no? specified) Distance to well (m)
« Previous
itod »
A. Identification of
constituent as either
a parent or a toxic
daughter
Figure 5.43 Tier 2 Input: Input Summary (23).
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5.5.2 Tier 2 Evaluation: Run Manager (24)
After you have verified that all Tier 2 inputs are correct, click the NEXr| button on
the Input Summary screen (23) to perform the Tier 2 evaluation. The Tier 2 Run
Manager (Screen 24) will be displayed.
In a Tier 2 evaluation, after you click on the START EPACMTP| button, the ground-
water model is automatically executed for each waste constituent for each applicable liner
scenario using the chosen waste 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 liner scenario requires one probabilistic Monte
Carlo modeling run consisting of 10,000 model realizations. Depending upon model
inputs and the speed of your personal computer, each modeling run may take from several
minutes to several hours. For this reason, we have developed a Run Manager dialog box
which displays the current status of your modeling analysis; this way, you will know that
the model is working and how much progress has been made at any given point in time.
The following sequence of screen images (Figures 5.44 through 5.46) demonstrate
how the Tier 2 Run Manager and the EPACMTP dialog box help you track the progress
of your Tier 2 modeling analysis.
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A. EPACMTP run
status and liner
protectiveness
summary
Tier 2 Evaluation - Run Manager (24)
EPACMTP Run Status
for Landfills
Index
Constituent Name
Related
Constituents
n Status No Liner
Single Liner
Composite
Liner
1 Aciylonitnls
Parent
2 Acrylamide Daughter
3 «n lie acid [ptopenoic acid] Daughter
«Erevious
Start EPACMTP
C. Go to
B. Launch EPACMTP
runs for selected set
of constituents
Figure 5.44 Tier 2 Evaluation: Run Manager (24) -
Appearance Before Launching EPACMTP Runs.
The features identified in Figure 5.44 are explained in more detail in the following
paragraphs.
Figure 5.44 shows a summary table listing all the constituents and liner scenarios
in a typical Tier 2 analysis prior to launching the first EPACMTP run. During an
EPACMTP run, a dialog box is displayed (Figure 5.45), allowing you to track the
progress of the model's execution. The summary table shown in the background (Figure
5.46) keeps you informed of the overall progress of the Tier 2 analysis. The EPACMTP
runs proceed from the first to the last selected constituent. For each constituent,
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EPACMTP runs are sequentially launched for the no-liner, single clay-liner, and
composite-liner scenarios until a protective scenario is found. That is, if the single clay-
liner scenario is determined to be protective for a given constituent, the composite-liner
scenario for that constituent is not modeled. For the LAU or user-defined liner/
infiltration scenarios, only one scenario per constituent is evaluated. During EPACMTP
model execution, the message "Running" appears in the table cell corresponding to the
current constituent and liner scenario. After the completion of a run, the results are
analyzed by IWEM to determine whether the liner scenario is protective for the current
constituent. An up-to-date summary of the results is displayed in the summary table as
shown in Figure 5.46.
A. EPACMTP Run Status and Liner Protectiveness 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 or not each liner scenario is
protective of ground water.
B. 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. During an EPACMTP model run, the dialog box
shown below in Figure 5.45 appears on-screen and displays the status of the current
model run, including estimated time to completion.
C. Go to Input Summary (23) screen
You can click the PREVIOUS button at the bottom left of the screen to go back to
the Tier 2 Input Summary (23)screen.
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iEPACMTP ¥2
File View State Help
: Processing Input Fte 107131_LFNL.in
INDUSTRIAL WASTE HANAGEHENT
EVALUATION HODEL
* GROUND-HATER PATHWAY
* FATE AND TRANSPORT ANALYSIS
*
* BASED ON
« EPA'3 COMPOSITE HODEL FOR LEACHATE
* MIGRATION HITH TRANSFORMATION PRODUCTS
VERSION 2.0
Leaching From
A Landfill Hich No Liner
Current Realisation:
58 OF 10000
Elapsed Time: 0:00:15 (hh:iiin:ss)
Estimated Time Remaining
In This Simulation: 0:37:29 (hh:in»:,—l
[fti nnlng
A. Status of
current
EPACMTP run
Figure 5.45 Tier 2 Evaluation: Run Manager (24) - EPACMTP
Dialog Box Displayed During Model Execution.
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A. Status of Current EPACMTP Run
A Run Manager dialog box will be displayed during each EPACMTP run to help
you monitor the model's progress in real time. Note that the information displayed on
this screen includes: constituent name, WMU type and liner scenario, current realization
number, time elapsed, and estimated time remaining.
The summary table displayed on the Run Manager (24) screen, presented below in
Figure 5.46, shows you the overall progress of the Tier 2 analysis - the liner
recommendation for each completed EPACMTP model run and which (if any) model
runs have not yet begun.
A. EPACMTP run
status and liner
protectiveness
summary
Tier 2 Evaluation - Run Manager (24)
EPACMTP Run State
for Landfills
Index
Constituent Name
Related
Constituents
Run Status
No Liner
Single Liner
Composite
Liner
1 Aerylonitnle F'arent Completed Not Protective ')"' Fioteetr> •
2 Acrylamide Daughter Completed Not Protective HntMotectrv
3 Acrylic acid [propenoic arirt] Daughter Completed Piott-ctivp i I. i i
«P_revious
C. Go to
screen
B. Go to
SurnmaijLResuItiUSj
Figure 5.46 Tier 2 Evaluation: Run Manager (24) -
Status and Liner Protectiveness Summary.
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The features identified in Figure 5.46 are explained in more detail in the following
paragraphs.
A. EPACMTP Run Status and Liner Protectiveness 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 or not each liner scenario is
protective of ground water.
B. Go to Summary Results (25) screen
You can click on the | NEXT| button at the bottom right of the screen to proceed to
the brief listing of the Tier 2 results that is presented on the Summary Results (25) screen.
C. Go to Input Summary (23) screen
You can click the PREVIOUS button at the bottom left of the screen to go back to
the Tier 2 Input Summary (23) screen.
5.5.3 Tier 2 Evaluation Summary: Summary Results Screen (Screen 25)
The presentation of the liner recommendation for the Tier 2 evaluation is
determined by which option you chose to specify the infiltration rate (either a location-
based estimate or a user-specified value) and your WMU type. But whichever infiltration
option you choose, the results are divided into two sets: summary results and detailed
results. The first set of results is a summary which reports a liner recommendation for
each individual waste constituent and the overall liner recommendation that is protective
for all constituents. The second set of results, the detailed results, present the data upon
which the liner evaluation is based. For each waste constituent, the expected leachate
concentration, the DAF, the Tier 2 LCTV, specified RGC type and value, and the
resulting 90th percentile ground-water concentration calculated by EPACMTP are listed.
These detailed results allow you to understand how the liner design recommendations
were developed.
The results of the Tier 2 Evaluation are first presented on-screen in a summary
form. The Summary Results screen provides a liner design recommendation for each of
the selected constituents which are listed by name and CAS number. The
recommendation is based on a comparison of the resulting 90th percentile ground-water
concentration and the specified RGC. If the ground-water concentration does not exceed
the specified RGC, then the evaluated liner scenario is protective for that constituent. If
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the ground-water concentration exceeds the specified RGC, then the evaluated liner
scenario is not protective for that constituent. Only the no-liner soil scenario is evaluated
for LAUs. In this case, if the no-liner scenario is not protective of ground water, then
land application of the modeled waste is not recommended at the site.
A. Tier 2 liner
recommendation
for each constituent
*K Tier 2 Output - Output Summary (25)
CAS Number Constituent Name
Mi
itnum Liner Recommendation
107-13-1 Actylonitrile
79-06-1 Acrylamide
79-10-7 acrylic acid [propenoic acid]
Based on consideration of the toxicity standards of all listed constituents, the Composite I iner
minimum liner recommended is:
< Erevious
detailed Results
Becommendation »
D. Go to
Results - No Liner (26)
screen
B. Overall Tier 2
liner recommendation
based on selected
toxicity standard(s)
C. Go to
Tier 2 Evaluation
(22J
Figure 5.47 Tier 2 Output (Summary): Summary Results (25).
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The features identified in Figure 5.47 are explained in more detail in the following
paragraphs.
A. Tier 2 Liner Recommendation for Each Constituent
If you evaluated a landfill, waste pile, or surface impoundment and used a
location-based estimate of the infiltration rate, the liner recommendation is the minimum
recommended liner of the three types that are evaluated (no liner, single clay liner, and
composite liner). If you evaluated a LAU and used a location-based estimate of the
infiltration rate, the resulting recommendation is whether or not land application of this
waste at this site will be protective of ground-water.
If you entered a site-specific infiltration rate (for any type of WMU), then the liner
recommendation is whether or not the modeled liner type is recommended as being
protective of ground water.
For a Tier 2 evaluation, the no-liner, single clay-liner, and composite-liner
recommendations are displayed in green text. If the composite liner is not protective,
then this message is displayed in red text. If the liner recommendation is "Not
Applicable," then this message is displayed in black text.
B. Overall Tier 2 Liner Recommendation Based on Selected Toxicity Standard(s)
The bottom of the screen displays an overall liner recommendation which is based
on consideration of all waste constituents (and their daughter products).
If EPACMTP predicts 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 groundwater. If the
modeled ground-water 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
LAUs, land application is not recommended). If the predicted ground-water
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. See Chapter 4 of the Guide (U.S. EPA, 2002d) for further
information.
For waste streams with multiple constituents, the least stringent liner design that is
protective for all constituents is the overall recommended liner design.
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C. Go to Tier 2 Evaluation Summary (29) screen
Clicking on the RECQMI\/ENDAT1ON| button will take you to the Tier 2 Evaluation
Summary screen where you can choose to view the Tier 2 report or save your analysis and
exit the IWEM software.
D. Go to Results - No Liner (26) screen
Clicking on the DETAILED RESULTS) button will take you to a detailed listing of the
Tier 2 results, including the constituent-specific modeling results for all evaluated liner
scenarios.
5.5.4 Tier 2 Output (Details) Screen Group (26, 27, and 28)
The detailed results table for each evaluated liner type presents the data on which
the liner recommendation are based. For each waste constituent, this information
includes the expected leachate concentration, the DAF, the Tier 2 LCTV, the specified
RGC type and value, the resulting 90th percentile ground-water concentration, and text
explaining whether or not the liner is recommended as being protective of ground water.
These detailed results allow you to understand how the liner design recommendations
were developed.
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, rather
than the three that are shown below in Figures 5.48 through 5.50.
Also, for a Tier 2 analysis of a LAU, only the no-liner scenario is evaluated since
engineered liners are not typically used at this type of facility. In this case, the detailed
results will consist of only one screen.
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f. Exposure
level
(ground-water
concentration)
01358 2 A Z88 HBN-lngestion
NonCancer
« previous
H. Goto
Summary Results (25)
Figure 5.48 Tier 2 Output (Details): Results-No Liner (26).
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F. Exposure
level
(ground-water
concentration)
-JaJxJ
$ - Composite I
ner (28)
Wi PercenMe F
ISSUE'S Level
107-13-1 Acrylcmittile
79-06-1 Acrylamide
0134 17 .< 7-IE IM Hbll Ingesln
0 008
79-10-7 Acrylic acid 01358 N/A N/A HBN - Ingestion
[pfopenosc scid] NoriCancet
previous
sults
H. Goto
Summary Results (25)
Figure 5.49 Tier 2 Output (Details): Results-Single Liner (27).
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F. Exposure
level
(ground-water
concentration)
H. Goto
Summary Results (25)
Figure 5.50 Tier 2 Output (Details): Results-Composite Liner (28).
The features identified in Figures 5.48 through 5.50 are explained below.
A. Entered Leachate Concentration
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.
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B. Dilution and Attenuation Factor
This column shows the 90th percentile value of the ground-water DAF calculated
by EPACMTP. DAF values are capped at IxlO30.
C. Estimated LCTV
The constituent- and liner-specific Tier 2 LCTV is also displayed on this screen.
The LCTV for organics is calculated as follows:
LCTV = DAF x RGC
where:
LCTV = leachate concentration threshold value (mg/L)
DAF = dilution-attenuation factor (EPACMTP model output)
(dimensionless)
RGC = reference ground-water concentration (MCL, HBN, or user-
specified value) (mg/L)
In Tier 2, the LCTV for metal constituents is an estimated value due to the non-
linear nature of metals adsorption (that is, for metals the DAF is not constant across all
leachate concentrations, as it is for organics). For this reason, an adjustment factor of
0.85 is used to estimate the LCTVs for metals in order to ensure adequate protection of
the ground water. The Tier 2 LCTV for metals is calculated as follows:
LCTV = DAF x RGC x 0.85
D. Selected RGC Type
The selected RGC type is displayed in this table for your reference. In addition to
regulatory MCLs, four types of HBNs can be evaluated in the IWEM software, covering
the direct ingestion and inhalation pathways, and carcinogenic and non-carcinogenic
health effects. However, if the existing values in the IWEM software are not appropriate
for your analysis, you may enter your own RGC to be used in the Tier 2 analysis. In any
case, the specified RGC type and value are displayed for each waste constituent.
E. Selected RGC Value
The selected RGC value is also displayed in this table for your reference. Note
that is value may be an MCL, an HBN, or a user-defined value.
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F. Exposure Level (Ground-water Concentration)
In order to determine whether or not this liner scenario is protective for a given
constituent, the resulting 90th percentile ground-water concentration is compared with the
specified RGC. If the ground-water concentration does not exceed the specified RGC,
then the evaluated liner is protective for that constituent. If the ground-water
concentration exceeds the specified RGC, then the evaluated liner is not protective for
that constituent.
G. Is the Exposure Level Less than the RGC?
The result of the comparison between the modeled 90th percentile exposure level
(ground-water concentration) and the specified RGC is displayed at the far right of this
table.
If the 90th percentile exposure level does not exceed the specified RGC, then the
evaluated liner is protective for that constituent 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
liner is not protective for that constituent and the text in the last column of this table will
read | NO for that constituent.
H. Go to Summary Results (25) Screen
Clicking on the RESULTS SuiVMARY button will take you back to the Tier 2
Summary Results (25) screen.
/. Go to Tier 2 Evaluation Summary (29) Screen
Clicking on the RECOMI\/ENDAT1ON| button will take you to the next screen, the Tier
2 Evaluation Summary (29) screen where you can choose to view the Tier 2 report or
save your analysis and exit the IWEM software.
5.5.5 Tier 2 Evaluation Summary (29)
The Tier 2 Evaluation Summary screen identifies the overall Tier 2 liner
recommendations and lists the available options within the IWEM software.
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A. Overall Tier 2
liner recommendation
Tier 2 Evalual ion Summary
Tier 2 Evaluation Summary (29)
The results of the Tier 2 analysis recommend the following design:
Composite Liner
You may choc se to print the results and exit this program. You may also return to the beginning of the Tier
1 or Tier 2 ev4luation, or you may conduct your own site-specific assessment.
Report
D. Go back to
previously viewed
results screen
Figure 5.51 Tier 2 Evaluation Summary (29).
The features identified in Figure 5.51 are explained in more detail in the following
paragraphs.
A. Overall Tier 2 Liner Recommendation
The Tier 2 liner recommendation is displayed at the top of this screen. For
landfills, surface impoundments, and waste piles that were modeled using a location-
based estimate of the infiltration rate, the available recommendations are: no-liner, single
clay-liner, composite-liner, and not protective. For LAUs that were modeled using a
location-based estimate of the infiltration rate, the available recommendations are: no-
liner and not protective. If you entered a user-specified value for the infiltration rate, the
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available recommendations are: protective and not protective. If your Tier 2 evaluation
results in a recommendation of "not protective", then the chosen WMU 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, 2002d) for further information.
B. List of IWEM Options
After reviewing your Tier 2 results on-screen, you have several options to
continue within the IWEM software:
• Go back to the previous screens of the Tier 2 results by clicking on the
| PREVIOUS| button.
• View the Tier 2 report by clicking the | REPORT) button.
At this point, you can also choose to save your results, exit the IWEM software, or
conduct a Tier 3 Evaluation. For more information about Tier 3 Evaluations, see Chapter
7A (Protecting Ground Water - Assessing Risk) of the Guide.
There are several ways to save the Tier 2 Evaluation:
• Click on the | FILE) 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. Please note that you cannot save any files to
the cd-rom, so you must specify a directory on your hard-drive or a floppy disk
to save the file.
• 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 later open up this file, you will have to perform either the Tier 1 or Tier 2
evaluation to create the corresponding results. Once you have completed an evaluation
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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.
You can exit the IWEM software by clicking on the | RLE) menu, and choosing
| EXIT . If you forget to save before trying to exit the IWEM software, a dialog box will
ask if you want to save your data before exiting the software.
You can open a previously saved IWEM analysis by clicking on any one of the
following options:
• IdPENl button on the Tool Bar
• IFlLE|OPENl selection from the Menu Bar
• IOPEN SAVED ANALYSIS (*.WEMFiLE)l radio button from the I IWEM ANALYSIS OpnoNSl
dialog box (see Item B in Section 5.3)
Once the lOPENl dialog box is displayed, highlight the appropriate file and click the
lOPENl button to open the desired file. You will then see a dialog box in which you can
specify what type of analysis you want to perform - Tier 1 or Tier 2.
C. Display Tier 2 Reports
Clicking on the REPORT button displays the IWEM Tier 2 Report.
Once the Tier 2 report is displayed on-screen, you can then use the following
toolbar buttons to print, save, and scroll through the pages of the report:
Print the report; the PRINT | dialog box then appears where you
can adjust printer setting or choose to print selected pages.
Export the report in order to save it to a file; after specifying the
file type, destination type, and the pages to be included, the
| CHOOSE EXPORT FILE | dialog box then appears; you can specify
the file type, and then select the file name and directory. The
file types in this list are dependent upon what software you have
installed on your PC. Most users will find that the option for
PDF format will produce a document-ready report.
View the next page of the report
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View the last page of the report.
View the previous page of the report
View the first page of the report.
Change the display size of the report.
Tier 2 Report Includes:
WMU facility data entered on screen 16
List of selected constituents and their corresponding leachable concentrations
entered on screen 20
List of Tier 2 input values and explanations of user-input data, as summarized on
screen 23
Tier 2 summary results for each selected constituent, based on the user-specified
RGC for each constituent
Tier 2 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
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An example Tier 2 report is included in this User's Guide in Appendix B.
D. Go Back to Previously Viewed Tier 2 Results
Click on the PREVIOUS button to return to the Tier 2 results that were previously
displayed. That is, if you navigated directly to the Tier 2 Evaluation Summary (29)
screen from the Summary Results (25) screen, then screen 25 is the screen you will return
to. However, if you viewed the detailed results before navigating to the Tier 2 Evaluation
Summary (29) screen, then clicking the | PREVIOUS | button will return you to the Results-
Composite Liner (28) screen.
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6.0 Understanding Your IWEM Input Values
This section of the User's Guide will assist you in understanding the WMU, waste
constituent and other fate and transport data that IWEM uses to evaluate whether a liner
design is protective.
Broadly speaking, there are three main categories of input values:
• WMU data,
• Waste constituent data, and
• Location-specific climate and hydrogeological data.
A Tier 1 analysis requires only a few key inputs. A Tier 2 analysis, which is
designed to provide a more accurate evaluation, requires you to provide additional site-
specific input data. Section 6.1 describes basic inputs that are common to both Tier 1 and
Tier 2 evaluations. Section 6.2 describes the additional inputs for a Tier 2 evaluation.
The IWEM Technical Background Document (TBD) provides additional detail on
the Tier 1 and Tier 2 input values. To assist you in cross-referencing the discussion on
each input parameter to the corresponding section(s) of the TBD, specific references to
the TBD are provided for each IWEM input. The references are indicated pictorially as
follows:
J Section x.y.z
TBD
6.1 Parameters Common to Both Tier 1 and Tier 2 Evaluations
The common parameters are:
1) WMU type.
2) Constituent(s) of concern that are present in the WMU, and
3) Leachate concentration (in mg/L) of each constituent.
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IWEM User's Guide Section 6.0
6.1.1 WMUType UJ Section 3.1; 4.2.1
TBD
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 application unit.
The latter is also sometimes called a land treatment unit. Figure 6.1 presents schematic
diagrams of the different types of WMU's 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, to a large extent, 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 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. In Tier 1, IWEM uses a national
distribution of values for surface impoundment operational life. In Tier 2, you can enter a
site-specific value. The Tier 2 default is 50 years.
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 to be present, similar to landfills. In Tier 1 analyses, IWEM
assumes that waste piles have a fixed operational life of 20 years, after which the waste
pile is removed. In Tier 2, you can provide a site-specific value for the operational life.
The default value is 20 years. After the operational period, IWEM assumes the waste pile
is removed.
Land Application Unit. Land application units (or land treatment units) are areas
of land receiving regular applications of waste which can be either tilled directly into the
soil or sprayed onto the soil and subsequently tilled into the soil. IWEM models the
leaching of wastes after they have been tilled with soil.
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Cover
unsaturated zone
V
saturated zone
(A) LANDFILL
unsaturated zone
V
saturated zone
(C) WASTE PILE
unsaturated zone
V
saturated zone
(B) SURFACE IMPOUNDMENT
unsaturated zone
v
saturated zone
(D) LAND APPLICATION UNIT
Figure 6.1 WMU Types Modeled in IWEM.
6-3
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IWEM User's Guide Section 6.0
IWEM does not account for the losses due to volatilization during or after waste
application. In Tier 1, land application units have a 40 year active life. In Tier 2, you can
enter a site-specific value. The Tier 2 default value for operational life is 40 years. Land
application units are evaluated for only the no-liner scenarios because liners are not
typically used at this type of facility.
6.1.2 Waste Constituents
The IWEM software includes a built-in database with 206 organic constituents
and 20 metals. Appendix A provides a list of these constituents. In IWEM you select the
waste constituents for each WMU scenario that you wish to evaluate from a drop-down
list, either by constituent name or by Chemical Abstract Service (CAS) identification
number, or from a list of constituents sorted by constituent name or by CAS number.
With each constituent, you also select a set of constituent-specific reference ground-water
concentrations (see Section 6.1.4) and fate and transport characteristics. The fate and
transport characteristics include sorption parameters and hydrolysis rate constants.
In Tier 1, you can only evaluate constituents found in the built-in database, and
you are not able to change the fate and transport characteristic values associated with each
constituent. In Tier 2, you can add constituents to IWEM's database as well as modify
fate and transport characteristic values for constituents already in the database.
6.1.3 Leachate Concentration tsUI Section 4.2.1.3
TBD
You must provide the leachate concentration in mg/L for each selected waste
constituent that you expect in the leachate that will infiltrate into the soil underneath a
WMU. 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.
6.1.4 Reference Ground-water Concentrations tsUI Section 5.0
TBD
Associated with each waste constituent is a set of RGCs that reflect not-to-exceed
exposure levels for both drinking water ingestion and shower inhalation cancer risks and
non-cancer hazards. These include regulatory MCLs and HBNs. Collectively, HBNs and
MCLs are referred to in IWEM as RGCs. Each type of RGC is briefly described below.
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6.1.4.1 Maximum Contaminant Level (MCL) IbU Section 5.0
TBD
For a number of constituents, the EPA has set MCLs as part of the National
Primary Drinking Water Regulations (NPDWR). The MCL is the maximum permissible
level of a contaminant in public water systems. 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.
6.1.4.2 Health-Based Number (HBN) !UJ Section 5.0
TBD
All constituents included in the IWEM software have one or more HBNs. An
HBN is the maximum exposure concentration of a contaminant in a domestic water
supply that will not cause adverse health effects. Health effects and certain exposure
assumptions are considered in the determination of the HBN, while other factors, such as
the cost of treatment, are not considered. The HBNs in IWEM are based on the ingestion
of drinking water and the inhalation of volatiles during showering. HBN values are based
on a target risk of IxlO"6 for carcinogens and a hazard quotient of 1 for non-carcinogens.
HBNs in IWEM were calculated using standard EPA risk assessment assumptions and
equations. An overview of the approach used to develop HBNs is given below. Section
5 of the IWEM Technical Background Document provides a detailed description.
Ingestion of Drinking Water fcsU Section 5.1
TBD
We calculated ingestion HBNs for a residential receptor who ingests contaminated
drinking water for 350 days/year. Consistent with EPA policy, the ingestion HBNs were
calculated to reflect consideration of children's exposure. The calculation of cancer
HBNs assumed an exposure duration of 30 years and used a time-weighted average
drinking water intake rate for individuals aged 0 to 29 years, equal to 0.0252 liters per day
per kilogram body weight. In the case of cancer HBNs, the 30-year exposure period
represents a high-end (95th percentile) value for population mobility. We chose the 30-
year period to cover ages 0-29 to ensure childhood years were included. Non-cancer
ingestion HBNs were developed to be protective of children aged 0 to 6 years; the
calculations used a daily ingestion rate that is representative of children in this age-group,
and is equal to 0.0426 liters per day per kilogram body weight.
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Inhalation of Volatiles During Showering fcsU Section 5.2
TBD
Inhalation HBNs were calculated for adults because we assumed that children take
baths. We assumed daily 15 minutes showers for 350 days per year over 30 years and
used a shower model to calculate the average constituent concentration in air to which an
individual is exposed during a day as a result of volatilization of a constituent in shower
water. We assumed that the shower water is ground water from the well modeled by
EPACMTP. We also made the important assumption that constituents are released into
household air only a result of showering activity, and that exposure to air-phase
constituents only occur in the shower stall and bathroom. EPA acknowledges that not
considering exposures to children who bathe in bathtubs may be a significant limitation.
However, we have not yet developed a "bath" model for evaluating children.
6.1.4.3 Selection of the RGC within the IWEM Software
Tier 1 LCTVs are provided for both MCLs and HBNs. In the case of HBNs, the
LCTV reflects the most restrictive pathway and effect, i.e., the lowest of the available
HBNs. At Tier 2, you can select the type of RGC (either MCL, ingestion HBN,
inhalation HBN, or all) that you wish to use. You may also enter your own constituent-
specific RGC values. For example, your state regulatory authority may request that you
use HBNs that are calculated using a different target risk level or a different assumption
regarding the weight of an adult. (Instructions regarding the selection of RGCs and
entering user-specified RGCs are provided in Section 5.4.1.6 of this User's Guide.)
6.2 Additional Parameters for a Tier 2 Evaluation
This section describes the additional parameters for which you can provide site-
specific values in a Tier 2 evaluation. There are two categories of Tier 2 input
parameters: required parameters for which you must provide site-specific values; and
optional parameters for which you can provide site-specific values if data are available.
When site-specific data for some of the optional model inputs are not available, the
suggested default values or distributions of values can be used.
6.2.1 Basis for Using Site-Specific Parameter Values
The Tier 1 evaluation provides a quick screening analysis of whether or not a
WMU design is protective for wastes of concern. The IWEM Tier 1 analysis
compensates for the lack of site-specific information by being conservative. Tier 1
LCTVs are based on simulating a wide range of conditions, and then selecting the 90th
percentile of the predicted ground-water concentration as the basis for assigning the
6-6
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IWEM User's Guide Section 6.0
LCTV. In other words, the Tier 1 evaluation is expected to be protective in 90% of the
cases.
The Tier 2 evaluation, which is designed to simulate a specific WMU, has less
uncertainty in its liner recommendation than a Tier 1 evaluation of the same site. This
reduction in uncertainty is achieved by using site-specific data which are both easily
measured and important to the model output.
6.2.2 Tier 2 Parameters
Table 6.1 provides a list of the Tier 2 IWEM parameters. The table indicates: (1)
the parameters the user may specify in Tier 2 grouped by the main input groups of the
IWEM software, (2) the units of measurement; (3) whether the parameter is a required
user input; (4) the IWEM default if the parameter is not a required user input; and (5) the
ranges of allowable input values.
Parameters that require user inputs are indicated with YES in the corresponding
column of the table. All other parameters are optional user inputs. The following
sections discuss the Tier 2 parameters in more detail.
6.2.2.1 Tier 2 Parameters that Require User Inputs
Parameters in Table 6.1 that are marked with YES in the 'Required User Input?'
column are those for which you must provide a site-specific value in Tier 2; the software
does not have a default value. In addition to selecting the WMU type and providing
constituent leachate concentrations, there are only four other key parameters for which the
user must provide data. They are:
• WMU Area;
• WMU Depth for landfills;
• Ponding Depth for surface impoundments; and
• Climate Center that is nearest to your site.
6.2.2.2 Optional Tier 2 Parameters
Except the required parameters listed above, all other Tier 2 parameters listed in
Table 6.1 are optional user input parameters. Use of site-specific data is strongly
recommended for these parameters, but if you do not have a value, the IWEM software
will allow you to select a default value.
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IWEM User's Guide
Section 6.0
Table 6.1 Tier 2 Parameters
Parameter
Units
Required
User
Input?
Default
Range
Min
Max
WMU Parameters
WMU Area
WMU Depth (LF only)
Ponding Depth (SI Only)
Sediment Layer Thickness (SI Only)
WMU Base Depth below ground surface
Operational Life (SI, WP, LAU)
Surface Water Body within 2,000
(SI Only)
Distance to Ground-Water Well
m2
m
m
m
m
yr
m
m
YES
YES
YES
-
-
-
-
-
0.2
0.0
(1)
360
150
1
>0
0.01
0.2
-100b)
1.0
0
0
l.OE+8
10
100
100a)
100b)
200
5,000
1,609
Subsurface Parameters
Subsurface Environment
Depth to Water Table
Saturated Zone Thickness
Hydraulic Gradient
Hydraulic Conductivity
Subsurface pH
- Solution limestone environment
- All other
-
m
m
m/m
m/yr
~
-
-
-
-
-
~
(2)
(3)
(3)
(3)
(3)
7.5
6.2
NA
0.1
0.3
>0
3.15
7
1
NA
1,000
1,000
1
IxlO8
14
14
Infiltration and Recharge Parameters
Infiltration Rate
Nearest Climate Center
Regional Soil Type
Waste Type Permeability
m/yr
-
-
-
-
YES
-
-
(4)
(5)
(6)
(6)
0
NA
NA
NA
100
NA
NA
NA
Constituent Parameters
Constituent Name
CAS Number
Koc (organics only)
Overall Decay Coefficient (organics only)
Acid Hydrolysis Rate
Neutral Hydrolysis Rate
-
-
L/kg
1/yr
l/(M-yr)
1/yr
-
-
-
-
-
-
(7)
(7)
(7)
(7)
(7)
(7)
NA
50-00-0
0.0
0.0
0.0
0.0
NA
999999-99-9
l.OE+10
100
l.OE+10
100
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IWEM User's Guide
Section 6.0
Table 6.1 Tier 2 Input Parameters (continued)
Parameter
Base Hydrolysis Rate
MCL
Ingestion HBN - Cancer
Ingestion HBN - Non Cancer
Inhalation HBN - Cancer
Inhalation HBN - Non Cancer
User RGC
Exposure Duration
Units
l/(M-yr)
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
vrs
Required
User
Input?
-
-
-
-
-
-
-
-
Default
(7)
(7)
(7)
(7)
(7)
(7)
(8)
(9}
Range
Min
0.0
>0
>0
>0
>0
>0
>0
>0
Max
l.OE+10
NA
NA
NA
NA
NA
NA
70
NA = Not Applicable
a) Value cannot be larger than impoundment ponding depth
b) Negative value indicates base is above ground surface; depth value cannot be larger than depth to water
table.
NOTES:
(1) Default operational life is 50 years for Surface Impoundments, 20 years for Waste Piles, and 40
years for Land Application Units.
(2) Select from the IWEM list; if you select type "unknown," the subsurface parameters will be set to
mean values from the IWEM nationwide database.
(3) Assigned from the IWEM database according to the selected subsurface environment.
(4) Assigned from the IWEM database according to the selected climate station, soil type or waste
type.
(5) You must select a center from the IWEM list, usually the center nearest to your WMU location.
(6) Select from the IWEM list; if you select type "unknown," the soil type or waste type will be chosen
randomly from the three known types during the Tier 2 modeling process.
(7) Applicable only when you wish to add constituents to the IWEM constituent list; you must provide
at least one MCL or HBN value for each new constituent.
(8) Applicable when you want to add an HBN to a constituent already in the IWEM database.
(9) Applicable only when you supply a user-specific RGC.
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IWEM User's Guide Section 6.0
6.2.2.3 Default Values for Missing Data
Default values for Tier 2 parameters are generally obtained from IWEM's internal
ground-water modeling and constituent property databases. The IWEM software 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.
6.2.2.4 How IWEM Handles Infeasible User Input Parameters
The IWEM software 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 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. Table 6.1 lists the minimum and maximum allowed values for each
Tier 2 parameter.
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 WMU. The extent of ground-water mounding depends on WMU
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 Tier 2 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.
6.2.3 Tier 2 Parameter Descriptions
This section provides a detailed description of the individual Tier 2 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.
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IWEM User's Guide Section 6.0
6.2.3.1 WMU Parameters fcU Sections 3.1, 4.2.1.3, 4.2.5
TBD
WMU Area (m2). This parameter represents the footprint area of the WMU (area
= length x width). This is a required user-input value for a Tier 2 evaluation. The area
must be entered in square meters. To convert other units to square meters, use the
following factors:
1 Acre = 4,046.9 m2
1 Hectare = 10,000 m2
1 ft2 = 0.093 m2
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. To convert other units to meters, use the following factors:
1 Foot = 0.305 m
1 Inch = 0.0254 m
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 the layer, if present, should not be counted as part of the
ponding depth. The ponding depth must be entered in meters. To convert other units to
meters, use the same conversion factors listed above.
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. To convert other units to meters, use the same conversion factors listed
above.
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 6.2. 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 0.0 meters, i.e., the base of the unit is level with the ground surface. To convert
-------
IWEM User's Guide Section 6.0
other units to meters, use the same conversion factors listed above. 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:
a) 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 input screen. In this case, set
the Depth of the WMU Base Below Ground Surface to zero (0.0).
b) 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
DEPTH OF THE WMU BASE
BELOW GROUND SURFACE-
V! GROUND SURFACE
A* 1
i;uAxxxxxl I
l\AXXXXXXAj I
DEPTH TO WATER TABLE
WATER TABLE y
SATURATED ZONE
THICKNESS
Figure 6.2 WMU with Base Below Ground Surface.
Operational Life (yr). For waste piles, surface impoundments, or land application
units, the operational life is an optional Tier 2 user input parameter. 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. See Section 6.1.1 for more details on leaching durations. 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. Default values for this
parameter are as follows:
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IWEM User's Guide Section 6.0
• Waste Pile = 20 years
• Land Application Unit = 40 years
• Surface Impoundment = 50 years
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
meters 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 2000 m (IWEM uses 360 m), or
• Exact distance is unknown but it is greater than 2000 m (IWEM uses 5000 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 6.3 depicts how the well distance is measured. This figure shows a plan view
(upper graph) and a cross-sectional view (lower graph) of a groundwater 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 6.3 also shows the location of the well.
IWEM always assumes that the well is located along the center line of the plume,
but the software randomly varies the depth of the well intake point (see lower graph)
during the Monte Carlo simulation process. The distance between WMU and the location
of the well is an optional user input parameter at Tier 2. This parameter must be entered
in meters, and has a default value of 150 meters (492 feet). 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 groundwater flow. If
you are unsure of the ground water flow direction, it will be protective to enter the
shortest distance between the edge of the WMU and the nearest location of concern.
6-13
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IWEM User's Guide
Section 6.0
PLAN VIEW
CONTAMINANT
PLUME
CENTERLINE
SECTIONAL VIEW
WMU
Figure 6.3 Position of the Modeled Well Relative to the Waste
Management Unit.
For compatibility with the EPACMTP ground-water model and consistency with
related EPA programs, we assume the well is located within 1 mile, or 1,609 meters,
from the WMU. IWEM will not accept larger values.
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. In IWEM evaluations, the depth of the well intake point is
always treated as a 'Monte Carlo' parameter, i.e., the tool will vary the well depth during
the model simulations, from zero (right at the water table), up to a maximum depth of 10
meters (30 feet) below the water table. If the value for the saturated thickness of your
6-14
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IWEM User's Guide Section 6.0
aquifer (see section 6.2.3.2) is less than 10 meters, 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.
6.2.3.2 Subsurface Parameters tsUI Section 4.2.3.1
TBD
The subsurface parameters in IWEM comprise a group of the most important
ground-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 a Tier 2 evaluation, the IWEM software provides
multiple options for entering subsurface parameters to assist you in making the best
possible use of information you have. The preferred option is to use accurate site-specific
values for all of the parameters, entering them directly in the appropriate data input
screens. The second option is where you have values for some, but not all of the
parameters. In this case, you enter the parameter values that you know, and IWEM makes
a best estimate of the missing values, utilizing knowledge the software has as to how the
various parameters tend to be correlated from its national ground-water modeling
database. The third, and least desirable, option is where you have no site-specific
subsurface data whatsoever. In this case, IWEM simply assigns parameter values that are
average values from its database.
The individual IWEM parameters in this group are discussed below.
Subsurface Environments. IWEM includes a built-in database of hydrogeological
parameters, organized by 12 different subsurface environments, plus one 'unknown'
category, as follows:
1) Metamorphic and Igneous
2) Bedded Sedimentary Rock
3) Till over Sedimentary Rock
4) Sand & Gravel
5) Alluvial Basins, Valleys & Fans
6) River Valleys and Floodplains with Overbank Deposits
7) River Valleys and Floodplains without Overbank Deposits
8) Outwash
9) Till and Till over Outwash
10) Unconsolidated and Consolidated Shallow Aquifers
645
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IWEM User's Guide Section 6.0
Subsurface Environment Descriptions
1) 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 US.
2) 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.
3) 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,
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.
4) 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.
5) 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.
6-16
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IWEM User's Guide Section 6.0
Subsurface Environment Descriptions (continued)
6) 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 which 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 5 to 10 feet.
7) 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.
8) 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.
9) 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.
10) 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.
11) 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.
12) 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."
13) 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 groundwater, saturated zone thickness, saturated zone hydraulic conductivity, and saturated zone hydraulic gradient) that are
simply national average values.
6-17
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IWEM User's Guide Section 6.0
11) Coastal Beaches
12) Solution Limestone
13) Unknown
This User's Guide provides a summary of the geologic and hydrogeologic
characteristic of each environment (see text box). You are cautioned that the assignment
of a subsurface environment is best done by a professional trained in hydrogeology and is
familiar with local site conditions.
Depth to the Water Table (m) This parameter is the vertical distance from the
ground surface to the water table as depicted in Figure 6.2. 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 WMU. The presence of a WMU, particularly a surface impoundment, may
cause a local rise in the water table called mounding. When you run a Tier 2 evaluation,
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 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 this will tend to result in a more protective IWEM result (i.e.,
IWEM will tend to predict higher ground-water exposure concentrations and hence return
a lower LCTV). It is also important to remember that 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 watertable, you should
enter that value as the Depth of the WMU Base Below the Ground Surface (see section
6.2.3.1 above).
The depth to ground water should be entered in meters. To convert from other
units to meters, use the factors listed in section 6.2.3.1. 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 meters.
If you selected one of the twelve 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.
Saturated Zone Thickness (m). This parameter represents the vertical distance
from the watertable down to the base of the aquifer, as shown in the diagram in Figure
6.2. Usually the base is an impermeable layer, e.g., bedrock. This parameter is used in
6-18
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IWEM User's Guide Section 6.0
the Tier 2 model simulation 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 6.2.3.1. 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 meters. If you selected one of
the twelve subsurface environments and did not specify the saturated thickness, IWEM
will treat the depth to the saturated thickness as a Monte-Carlo variable and use a
distribution of values that is appropriate for the selected subsurface environment.
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 WMU location. The gradient is
meant to represent the 'natural' ground-water gradient as it is, or would be, without
influence from the WMU. The presence of a WMU, particularly a surface impoundment,
may cause local mounding of the water table and associated higher local ground-water
gradients. When you run a Tier 2 evaluation, 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 of each liner design as part of the modeling evaluation.
The hydraulic gradient, together with the hydraulic conductivity (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. The Tier 1 and Tier 2 evaluations are
based on the maximum constituent concentrations at the well, rather than how long it
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IWEM User's Guide Section 6.0
might take for the exposure to occur, and therefore a higher ground-water flow rate may
result in lower predicted exposure levels at the well.
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 twelve
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.
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. For the same reasons as
discussed above, assigning a low hydraulic conductivity value will not necessarily result
in lower predicted ground-water exposures and higher LCTVs. In a broader sense, it
means that siting a WMU 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 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. To convert from other units, use the following factors:
1 meter/second = 31,536,000 m/yr
1 foot/second = 9,612,173 m/yr
1 gallon/day/foot2 = 14.89 m/yr
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.
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
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IWEM User's Guide Section 6.0
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 may also affect
the hydrolysis rate of organic constituents; some constituents degrade more rapidly or
more slowly as pH varies. 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 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.
6.2.3.3 Infiltration and Recharge Parameters tsUI Section 4.2.2
TBD
In IWEM, the infiltration rate is defined as the rate (annual volume divided by
WMU area) at which leachate flows from the bottom of the WMU (including any liner)
into the unsaturated zone beneath the WMU. Recharge is the regional rate of aquifer
recharge outside of the WMU. For landfills, waste piles, and land application units, the
infiltration rate is primarily determined by the local climatic conditions, especially annual
precipitation, and WMU liner characteristics. For surface impoundments, the infiltration
rate from the unit is a function of the surface 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.
The WMU related parameters are entered in IWEM in the WMU Parameters
group (see Section 6.2.3.1). The location and soil related parameters are entered in the
Infiltration and Recharge Parameters group. 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 in Tier 2. 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. The specific IWEM parameters in this group are as follows.
Site-specific Infiltration Rate (m/yr). This parameter represents the actual annual
volume of leachate, per unit area of the WMU, which flows from the bottom of the WMU
into the unsaturated zone underneath the WMU. The performance characteristics of a
liner, if present, are among the most important factors controlling the infiltration rate, and
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IWEM User's Guide Section 6.0
therefore, the rate of leachate release. IWEM provides you the option to enter a site-
specific infiltration 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 in Tier 1 and as defaults in a
Tier 2 evaluation. 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.
The infiltration rate in IWEM must be entered in units of meter/year. To convert
from other units, use the following factors:
1 foot/year = 0.305 m/yr
1 inch/year = 0.0254 m/yr
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 6.4 shows the geographic locations of the 102 climate stations in
the United States.
Regional Soil Type. In order to assign an appropriate recharge rate, IWEM needs
to know the dominant, regional soil type in the vicinity of 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.
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IWEM User's Guide Section 6.0
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
Tier 2 Monte Carlo process, with each type having equal probability. That is, IWEM will
use a uniform probability distribution.
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-Nahua
• La
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IWEM User's Guide Section 6.0
6.2.3.4 Constituent Parameters INd!! Section 5.0
IWEM includes a database of 206 organic constituents and 20 metals. Appendix
A provides a list of these constituents and their properties. The database provides the
following information for each constituent.
• Descriptive Data: Name,
CAS Number
• Physical and Constituent Properties: Organic Carbon Partition
Coefficient (KJ
Metals sorption isotherm data (kd)
Hydrolysis Rate Constants
• Reference Ground-water Concentrations: Maximum Contaminant Level (MCL)
Health Based Numbers (HBN)
To preserve the integrity of the database, IWEM gives you limited flexibility to
modify these data. IWEM does give you the option of specifying an overall constituent
decay rate which can include biodegradation, proving a constituent partitioning
coefficient (kd), and specifying one additional RGC to augment the built-in MCL and
HBN values.
IWEM allows you to add new constituents to its database and this provides an
indirect mechanism to assign different constituent parameter values, by entering a
constituent of interest as a 'new' constituent in the database with its own parameter
values.
The following sections discuss the IWEM constituent parameters.
Descriptive Data
Constituent Name and CAS Number. These parameters are used in IWEM to
identify each constituent. 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.
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IWEM User's Guide Section 6.0
Physical and Constituent Properties fcsU Section 4.2.4
TBD
The physical and constituent properties that affect subsurface fate and transport
include sorption parameters and degradation parameters.
Organic Carbon Partition Coefficient (Koe). This parameter describes the sorption,
or affinity of a constituent to attach itself to soil and aquifer grains. This parameter is
applicable 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., 1983). 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.
In IWEM, Koc has units of liters/kilogram (L/kg) or, equivalently, milliliters/gram
(mL/g).
Metals Isotherm Data. In the case of metals, sorption is expressed in the partition
coefficient kd. IWEM provides a set of kd values calculated using the MINTEQA2
geoconstituent speciation model for each metal. Rather than using a single kd value for
each metal constituent, IWEM includes multiple sets of kd values to reflect the impact of
variations in ground-water pH and other geochemical conditions. Each set of kd values is
referred to as a sorption isotherm. The sorption parameters for metals in IWEM are part
of the software's built-in database and they cannot be modified by the user. Further
information on how the MINTEQ sorption isotherms were developed can be found in the
IWEM Technical Background Document and the EPACMTP Parameters/Data
Background Document.
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.
Hydrolysis 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
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IWEM User's Guide Section 6.0
rate 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.
Biodegradation
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.
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.
By default, IWEM does not explicitly take into account biodegradation processes,
and the IWEM constituent database does not include biodegradation rates. However, in
Tier 2, the IWEM software allows you to add a constituent-specific biodegradation decay
coefficient to its database, as part of the constituent properties input group8. 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.
Reference Ground-Water Concentrations IbUI Section 5.0
TBD
The final set of parameters in the IWEM constituent database is a set of
constituent-specific RGCs, comprising MCLs and risk-based HBNs.
The use of these RGCs in IWEM is discussed in Chapter 7 of this User's Guide.
The derivation of the HBN values is discussed in Section 5 of the IWEM Technical
Background Document. You cannot change existing RGCs in the IWEM database. You
can, however, add a user-specified RGC value for each constituent in the database when
selected for a Tier 2 analysis. IWEM imposes no restrictions on user-specified RGCs,
Strictly speaking this decay coefficient can represent any first-order transformation process other
than hydrolysis, which is already explicitly considered in IWEM.
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IWEM User's Guide Section 6.0
other than that they should be expressed in units of mg/L and an exposure duration is
provided (in years) that is consistent with the way the RGC was derived.
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.
If you wish to add constituents to the IWEM database, you will be required to
provide at least one RGC for each new constituent, either a MCL, an ingestion HBN, or
an inhalation HBN. Consult the IWEM Technical Background Document for details on
the derivation of HBN values. This mechanism also provides an indirect way of using
modified MCL and/or HBN values for constituents that are already in the database. In this
case, you can add the constituent to the database as a 'new' constituent and provide your
own HBN values.
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IWEM User's Guide Section 7.0
7.0 Understanding Your IWEM Results
After completing an analysis, IWEM provides a recommendation for a liner
design for a WMU or the appropriateness of land application. Section 7 provides
guidance on how IWEM may assist you in answering the following questions:
• 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?
• What are the maximum allowable leachate concentrations for all constituents
in a waste for a particular type of WMU and liner design?
• Should you consider a Tier 3 assessment?
The IWEM liner recommendations and determination of maximum allowable
leachate concentrations are based on protective ground-water concentrations at wells. In
Tier 1, IWEM uses the tabulated LCTV values that represent protective national
screening values. In Tier 2, IWEM calculates LCTVs to provide guidance on what
leachate levels need to be achieved, for instance through treatment, to safely allow
disposal in a particular WMU design. To help you understand the IWEM results, we will
discuss LCTVs first.
7.1 Leachate Concentration Threshold Values (LCTVs)
An LCTV is the maximum concentration of a constituent in the waste leachate
that is protective of ground water. That is, if the concentration in the leachate does not
exceed the LCTV, then the concentration in ground water at the well will not exceed the
RGC. IWEM uses the EPACMTP fate and transport model to calculate LCTVs.
EPACMTP is a fate and transport model that simulates the concentration of a constituent
in ground-water, as a function of the constituent's concentration in the waste leachate.
The LCTV is determined by comparing the predicted well concentration against a
selected RGC, i.e., an MCL or HBN. By definition, the LCTV is the value of the leachate
concentration for which the well concentration is equal to the RGC. LCTVs depend on:
1) the combined effects of WMU design characteristics and hydrogeological fate and
transport processes; and 2) the effect of constituent-specific regulatory standards such as
an MCL and constituent toxicity represented by the HBN.
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IWEM User's Guide Section 7.0
Tier 1 LCTVs are different from Tier 2 LCTVs. LCTVs from the Tier 1 analysis
are generally applicable to sites across the country. Tier 2 LCTVs on the other hand, are
based on site-specific data for several sensitive parameters and are not applicable to other
sites.
7.2 Limits on the LCTV
While the LCTVs are based on fate and transport modeling, and regulatory and
risk-based ground-water standards, EPA also considered other factors in developing final
LCTV values for some waste constituents. These are described in this section.
7.2.1 Toxicity Characteristic Rule (TC Rule) Regulatory Levels fcU Section 6.2
TBD
In 1990, EPA adopted the Toxicity Characteristic (TC) Rule making wastes
containing certain constituents at or above listed leachate concentrations a hazardous
waste.
For any waste constituent included in the TC rule, we capped the LCTV at the TC
Rule Regulatory Level. This level is the leachate concentration above which the waste is
considered to be a hazardous waste (U.S. EPA, 1990). TC levels have been determined
for the constituents listed in Table 7.1.
7.2.2 1,000 mg/L Cap fcU Section 6.2
TBD
EPA does not expect leachate concentrations from WMUs covered by this
guidance to exceed 1,000 mg/L for a single constituent, and therefore, has limited the
expected waste constituent leachate concentrations to be less than or equal to 1,000 mg/L.
One of the reasons to cap the leachate concentration in IWEM is that the fate and
transport assumptions in IWEM may not be valid at high concentrations. For instance,
high leachate concentrations may indicate the presence of a free organic phase.
Consequently, all Tier 1 and Tier 2 LCTVs are capped at a maximum value of 1,000
mg/L.
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IWEM User's Guide
Section 7.0
Table 7.1 Toxicity Characteristic Leachate Levels
Waste Constituent
Arsenic
Barium
Benzene
Cadmium
Carbon Tetrachloride
Chlordane
Chlorobenzene
Chloroform
Chromium
o-cresol
m-cresol
p-cresol
2,4-D
1 ,4-dichlorobenzene
1 ,2-dichloroethane
1 , 1 -dichloroethylene
2,4-dinitrotoluene
Endrin
Heptachlor
Hexachlorobenze
TC Rule Leachate
Regulatory Level
(mg/L)
5
100
0.5
1
0.5
0.03
100
6
5
200
200
200
10
7.5
0.5
0.7
0.13
0.02
0.008
0.13
Waste Constituent
Hexachloro-1 ,3-butadiene
Hexachloroethane
Lead
Lindane
Mercury
Methoxychlor
Methyl ethyl ketone
Nitrobenzene
Pentachlorophenol
Pyridine
Selenium
Silver
Tetrachloroethylene
Toxaphene
Trichloroethylene
2,4,5-trichlorophenol
2,4,6-trichlorophenol
2,4,5-TP acid (silvex)
Vinyl chloride
TC Rule Leachate
Regulatory Level
(mg/L)
0.5
3
5
0.4
0.2
10
200
2
100
5
1
5
0.7
0.5
0.5
400
2
1
0.2
7.2.3 Constituents with Toxic Daughter Products
I Section 6.2
TBD
A number of the constituents included in the IWEM constituent database can be
transformed in soil and ground water into one or more toxic daughter products as a result
of hydrolysis reactions. For these constituents, the LCTVs are calculated such that they
accommodate both the parent constituent as well as any toxic daughter products. For
instance, if a parent waste constituent rapidly hydrolyses 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 final LCTV for this constituent
would be based on the exposure caused by the daughter product, under the protective
assumption that the parent compound fully transforms into the daughter product. If an
IWEM constituent has more than one toxic daughter product, the final LCTV is based on
the LCTV for the most protective compound in the parent-daughter sequence. If the
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IWEM User's Guide Section 7.0
LCTV of the parent constituent is lower than that of the daughter, the LCTV of the parent
remains unchanged. Additionally, if the daughter constituent has a particular RGC but
the parent constituent does not, the RGC of the daughter product is used to determine the
parent constituent LCTV. This methodology is designed to be protective of downgradient
ground water in terms of both the parent waste constituent and its daughter constituent(s).
The IWEM constituent database includes information on the toxic daughter
products associated which each hydrolyzing constituent, and the user does not need to
know which constituents transform into toxic daughter products. In Tier 1, the capping
the LCTV of parent constituents at the LCTV of their respective daughters is transparent
to the user. The capping of LCTVs is done automatically by the software and are flagged
in the Tier 1 tables and reports.
In a Tier 2 evaluation, if you select a waste constituent that hydrolyses, the IWEM
software will automatically add any toxic daughters products associated with that
constituent to the evaluation. In the Tier 2 input screens, daughter products are listed
immediately after their parent(s) in the Toxicity Standards Screen (Screen 22, see Figure
5.23). Constituents that are included because they are daughter products of constituents
in the waste, are identified as such in the input screens. In the Tier 2 reports, the results
of all waste constituents and any toxic daughter constituents produced by hydrolysis are
shown in the Tier 2 report. Daughter products are listed separately from parent
constituents, but for each daughter product, the parent waste constituent from which it
originated is identified.
Due to the chemical transformation of waste constituents, it is possible the same
constituent is included more than once in the evaluation. A constituent can be selected
because it is present in the waste, but it can also be added by the IWEM software because
it is produced as the result of hydrolysis transformations on one or more other waste
constituents. IWEM evaluates each occurrence of the constituent separately, and the
same constituent may lead to different liner recommendations in the same Tier 2
evaluation. For instance, assume that a constituent is present at low concentration in the
waste itself, but this compound is also produced as the result of hydrolysis of a second
waste constituent which is in the waste at a much higher concentration. IWEM will first
evaluate the constituent as an original waste constituent. In this example, we assumed
that the concentration in the waste is low, and the IWEM software in that case may
recommend a no-liner design as being protective. Next, IWEM will evaluate the ground-
water impact of the same constituent as a daughter product resulting from the
transformation of the second waste constituent. Because this second waste constituent
(the parent) is present in the waste at high concentrations, its transformation may cause
the ground-water concentration of our constituent of concern (which is now evaluated as
a daughter product) to be so high that IWEM determines that a no-liner design is not
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IWEM User's Guide Section 7.0
protective. This example would lead to a result in which the same constituent has two
different liner recommendations.
Even though the chemical compound is the same, IWEM treats these two
instances as if they were different constituents. One of the reasons EPA chose to do this,
is that it allows the user to make waste management decisions in terms of the constituents
that are actually present in the waste. In the example described here, an option may be to
treat the waste to reduce constituent concentrations to acceptable levels. In our example,
the goal should be not to reduce the level of the constituent of concern in the waste (it is
only present at low levels), but rather to reduce the concentration of its parent constituent.
Doing this will automatically reduce the ground-water impact of its daughter product(s).
7.3 IWEM Liner Recommendations Udl Section 6.3
TBD
IWEM makes liner recommendations by identifying the minimum design that is
protective of ground water for all waste constituents. In Tier 1, a liner design is
protective if the expected leachate concentrations for all waste constituents are less than
the LCTV determined by IWEM for the same constituents. In the case of LAUs, land
application of waste is considered appropriate if the leachate concentrations of all
constituents do not exceed LAU LCTVs.
The IWEM Tier 1 software automatically performs the comparisons of leachate
concentration to all of the LCTVs for each waste constituent and liner scenario. The
results of the evaluation are presented in terms of a MCL summary and a HBN summary.
The HBN summary reflects the liner recommendation based on the most protective, that
is the lowest, HBN available for each constituent. The recommendation also takes into
account the possible formation of toxic daughter products, as discussed in Section 7.2.3.
If the leachate concentrations for all constituents are lower than the corresponding
no-liner LCTVs, then no liner is recommended as being sufficiently protective of
groundwater. If any leachate concentration is higher than the corresponding no-liner
LCTV, then a minimum of a single clay liner is recommended. If any leachate
concentration is higher than the corresponding single clay liner LCTV, then a minimum
of a composite liner is recommended. If any concentration is higher than the composite
liner, consider pollution prevention, treatment, or additional controls. For waste streams
with multiple constituents, the recommended liner design is the most protective minimum
recommended liner.
After conducting a Tier 1 analysis, you can choose to implement the Tier 1
recommendation by designing the unit based on the liner recommendations given by the
IWEM software. If you choose to implement the Tier 1 recommendation, consultation
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IWEM User's Guide Section 7.0
with state authorities is recommended to ensure compliance with state regulations, which
may require more protective measures than the Tier 1 lookup tables recommend.
Alternatively, if the waste has one or very few "problem" constituents that call for a more
stringent and costly liner system (or which make land application inappropriate), evaluate
pollution prevention, recycling, and treatment efforts for those constituents.
If, after conducting the Tier 1 analysis, 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 Tier 2
analysis or a site-specific groundwater fate and transport analysis (Tier 3).
In a Tier 2 evaluation, IWEM uses the EPACMTP fate and transport model to
determine the ground-water exposure concentration that is expected for each waste
constituent given its leachate concentration. 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. Analogous to Tier 1 (which uses a
90th percentile LCTV value), IWEM uses the 90th percentile of the ground-water well
exposure concentration in Tier 2 to make liner recommendations. The software compares
the 90th percentile ground-water exposure concentration to the RGC(s) for that
constituent. IWEM first makes this evaluation for the no-liner scenario. If the ground-
water exposure concentration is less than the applicable RGC(s), then the no-liner
scenario is protective for that constituent. 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, then IWEM recommends the no-liner
scenario as being protective and the evaluation is complete. However, if the ground-
water exposure concentrations of one or more waste constituents exceed their RGCs, then
the no-liner scenario is not protective, and IWEM will evaluate the single clay liner
scenario (unless the WMU is a LAU). If the single clay liner scenario is protective for all
constituents, IWEM will recommend this design. If any waste constituents fail the single
clay liner design, then IWEM will recommend at least a composite liner.
In a Tier 2 evaluation, IWEM also calculates LCTVs. The Tier 2 LCTVs are
different from the Tier 1 values; they represent location-adjusted thresholds. While the
Tier 2 LCTVs are not directly used in IWEM to make liner recommendations, they are
displayed on the detailed results screen, and printed in the IWEM reports. These LCTVs
can be used in the same manner as in Tier 1 to identify pollution prevention, recycling, or
treatment alternatives to reduce the leachate concentrations of "problem" constituents to
levels that allow disposal of a waste in a less stringent WMU design.
7-6
-------
IWEM User's Guide Section 7.0
The Monte Carlo simulations required for a Tier 2 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,
IWEM will first perform the liner evaluations from least protective (no-liner) to most
protective (composite liner). If during this process, IWEM identifies a liner design that is
protective for all constituents (for instance, a single clay liner), it will stop the evaluation
process, and not evaluate more protective designs (in the example case, it would skip the
composite liner evaluation).
After conducting the Tier 2 Evaluation, you can choose to implement the Tier 2
recommendation by designing the unit based on the liner recommendations given by the
IWEM software or continue to a Tier 3 analysis. If you choose to implement the Tier 2
recommendation, consultation with state authorities is recommended to ensure
compliance with state regulations, which may require more protective measures than the
Tier 2 results recommend.
If after conducting the Tier 2 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 groundwater fate and transport analysis (Tier 3).
7-7
-------
IWEM User's Guide
Section 8.0
8.0 Trouble Shooting
The IWEM Version 1.0 has been extensively tested on the following
combinations of Windows operating system and Internet Explorer:
Latest versions of MS Windows operating
systems
95 (Version 4.00.950B)
98 Second Edition (Version 4.10.2222A)
NT 4.0 (Service Pack 6 a)
2000 (Service Pack 2)
XP (Version 2002)
Corresponding version of MS Internet
Explorer
Version 5.5 Service Pack 2
Version 6.0
Version 6.0
Version 6.0
Version 6.0
If you encounter any problems during installation, it is likely that your operating
system and/or version of Internet Explorer are not up-to-date. Check the version of your
operating system and Internet Explorer and compare them to the list above. If either of
these two are not up-to-date, visit the Microsoft Support web site at
http://support.microsoft.com, click on the |DCWMLOADSOFTWARE| link, and then click on
either the |MCROSCFT\MNDOV\S UPDATES] link or the (INTERNET EXPLORER link and follow the
prompts to download and install the updates. Check with your system administrator if
you do not have the correct privileges to install software on your computer.
How do I determine what version of Windows I am using?
Right click on the (MYGoivPirTER icon on your desktop and select PROPERTIES from
the pop-up menu. A dialog box will appear and near the top will be the version
information of Windows installed on your computer.
How do I determine what version of Internet Explorer I am using?
Start Internet Explorer, click on I^LP ABOUT INTERNET EXPLORER]. A dialog box will
appear and list first is the version of Internet Explorer installed on your computer.
What do I do if I am still having problems?
If your operating system and Internet Explorer versions are up-to-date and you
still encounter problems installing or running the IWEM software, please contact the
RCRA Information Center in any of the following ways:
8-1
-------
IWEM User's Guide
Section 8.0
• E-mail: rcra-docket@epa.gov
• Phone: 703-603-9230
• Fax: 703-603-9234
• In person: Hours: 9:00 am to 4:00 pm, weekdays, closed on Federal Holidays
Location: USEPA
West Building Basement
1300 Constitution Ave., NW
Washington, D.C.
• Mail: RCRA Information Center (5305W)
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
When contacting the RCRA Information Center, please cite RCRA Docket
number: F1999-IDWA-FFFFF.
8-2
-------
IWEM User's Guide Section 9.0
9.0 References
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, 1990. Toxicity Characteristic Final Rule. 55 FR 11796. March 29, 1990.
U.S. EPA, 1991. MINTEQA2/PRODEFA2, A Geochemical Assessment Model for
Environmental Systems: Version 3.0 User's Manual EPA/600/3-91/021, Office of
Research and Development, Athens, Georgia 30605.
U.S. EPA, 1993. Environmental Fate Constants for Organic Chemicals under
Consideration for EPA's Hazardous Waste Identification Projects. Compiled and
edited by Heinz Kollig. Environmental Research Laboratory, Office of Research
and Development, Athens, GA.
U.S. EPA, 1996d. Drinking Water Regulations and Health Advisories. Office of Water,
Washington, DC. October (EPA 822-B-96-002).
U.S. EPA, 1997. Guiding Principles for Monte Carlo Analysis. EPA/630/R-97/1001
Risk Assessment Forum, Washington, DC 20460.
U.S. EPA, 2002a. EPACMTP Technical Background Document. Office of Solid Waste,
Washington, DC.
U.S. EPA, 2002b. EPACMTP Parameters/Data Background Document Office of Solid
Waste, Washington, DC.
U.S. EPA, 2002c. IWEM Technical Background Document.. Office of Solid Waste,
Washington, DC.
U.S. EPA, 2002d. Guide for Industrial Waste Management. Office of Solid Waste,
Washington, DC.
Verschueren, K., 1983. Handbook of Environmental Data on Organic Chemicals. Van
Nostrand Reinhold Co., New York.
9-1
-------
Appendix A
List of Waste Constituents
-------
IWEM User's Guide
Appendix A
Appendix A
List of Waste Constituents
CAS Number
Constituent Name
CAS Number
Constituent Name
Organics
83-32-9
75-07-0
67-64-1
75-05-8
98-86-2
107-02-8
79-06-1
79-10-7
107-13-1
309-00-2
107-18-6
62-53-3
120-12-7
56-55-3
71-43-2
92-87-5
50-32-8
205-99-2
100-51-6
100-44-7
111-44-4
39638-32-9
117-81-7
75-27-4
74-83-9
106-99-0
71-36-3
85-68-7
88-85-7
75-15-0
56-23-5
57-74-9
126-99-8
106-47-8
108-90-7
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
B enz { a } anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzofb jfluoranthene
Benzyl alcohol
Benzyl chloride
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene, 1, 3-
Butanol
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro- 1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
510-15-6
124-48-1
75-00-3
67-66-3
74-87-3
95-57-8
107-05-1
218-01-9
108-39-4
95-48-7
106-44-5
1319-77-3
98-82-8
108-93-0
108-94-1
72-54-8
72-55-9
50-29-3
2303-16-4
53-70-3
96-12-8
95-50-1
106-46-7
91-94-1
75-71-8
75-34-3
107-06-2
156-59-2
156-60-5
75-35-4
120-83-2
94-75-7
78-87-5
542-75-6
10061-01-5
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene, 3- (Allyl Chloride)
Chrysene
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
DDD
DDE
DDT, p,p '-
Diallate
Dibenz { a,h } anthracene
Dibromo-3-chloropropanel ,2-
Dichlorobenzenel ,2-
Dichlorobenzenel ,4-
Dichlorobenzidine3 ,3 '-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethanel ,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans- 1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene l,3-(mixture of isomers)
Dichloropropene cis-1,3-
A-l
-------
IWEM User's Guide
Appendix A
Appendix A (continued)
List of Waste Constituents
CAS Number
10061-02-6
60-57-1
84-66-2
56-53-1
60-51-5
119-90-4
68-12-2
57-97-6
119-93-7
105-67-9
84-74-2
99-65-0
51-28-5
121-14-2
606-20-2
117-84-0
123-91-1
122-39-4
122-66-7
298-04-4
115-29-7
72-20-8
106-89-8
106-88-7
110-80-5
111-15-9
141-78-6
60-29-7
97-63-2
62-50-0
100-41-4
106-93-4
107-21-1
75-21-8
96-45-7
91-20-3
Constituent Name
Dichloropropene trans- 1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3-
Dimethyl formamide N,N- [DMF]
Dimethylbenzf a} anthracene 7,12-
Dimethylbenzidine 3,3-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine, 1, 2-
Disulfoton
Endosulfan (Endosulfan I and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane, 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate, 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Naphthalene
CAS Number
206-44-0
50-00-0
64-18-6
98-01-1
319-85-7
58-89-9
319-84-6
76-44-8
1024-57-3
87-68-3
118-74-1
77-47-4
55684-94-1
34465-46-8
67-72-1
70-30-4
110-54-3
7783-06-4
193-39-5
78-83-1
78-59-1
143-50-0
126-98-7
67-56-1
72-43-5
109-86-4
110-49-6
78-93-3
108-10-1
80-62-6
298-00-0
1634-04-4
56-49-5
74-95-3
75-09-2
1746-01-6
Constituent Name
Fluoranthene
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro- 1 ,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
Indeno{l,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
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)
Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
A-2
-------
IWEM User's Guide
Appendix A
Appendix A (continued)
List of Waste Constituents
CAS Number
98-95-3
79-46-9
55-18-5
62-75-9
924-16-3
621-64-7
86-30-6
10595-95-6
100-75-4
930-55-2
152-16-9
56-38-2
608-93-5
30402-15-4
36088-22-9
82-68-8
87-86-5
108-95-2
62-38-4
108-45-2
298-02-2
85-44-9
1336-36-3
23950-58-5
75-56-9
129-00-0
110-86-1
94-59-7
57-24-9
100-42-5
95-94-3
51207-31-9
Constituent Name
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-
Tetrachlorodibenzofuran, 2,3,7,8-
CAS Number
630-20-6
79-34-5
127-18-4
58-90-2
3689-24-5
137-26-8
108-88-3
95-80-7
95-53-4
106-49-0
8001-35-2
75-25-2
76-13-1
120-82-1
71-55-6
79-00-5
79-01-6
75-69-4
95-95-4
88-06-2
93-72-1
93-76-5
96-18-4
121-44-8
99-35-4
126-72-7
108-05-4
75-01-4
108-38-3
95-47-6
106-42-3
1330-20-7
Constituent Name
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-l,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
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)
A-3
-------
IWEM User's Guide
Appendix A
Appendix A (continued)
List of Waste Constituents
CAS Number
Constituent Name
CAS Number
Constituent Name
Metals
7440-36-0
7440-38-2
7440-39-3
7440-41-7
7440-43-9
16065-83-1
18540-29-9
7440-48-4
7440-50-8
16984-48-8
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium (III)
Chromium (VI)
Cobalt
Copper
Fluoride
7439-92-1
7439-96-5
7439-97-6
7439-98-7
7440-02-0
7782-49-2
7440-22-4
7440-28-0
7440-62-2
7440-66-6
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
A-4
-------
Appendix B
Sample Reports From Tier 1 and Tier 2
-------
XLX
Tier 1 Evaluation Results
6/20/2002
5:00:55PM
Recommendation :
Composite Liner
Facility Type
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
Landfill
Southern Industries Landfill
122 Industrial Ave
Raleigh
NC
27611
October 31, 1998
List of Constituents Selected by the User
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Minimum Liner Recommendation Based on MCL
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
Minimum Liner Recommendation
No Liner
Single Liner
Single Liner
Minimum Liner Recommendation Based on HBN
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
Minimum Liner Recommendation
Composite Liner
Single Liner
No Liner
1 of 7
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In the following tables, the LCTV is generally calculated as LCTV = DAF * RGC. However, in some instances, the DAF is denoted here with an asterisk (*). This occurs
when the ground-water concentration is either exceedingly low, thus capping the LCTV, or the LCTV is capped by some other constraint. In instances where the toxic
daughter cap is applied, the RGC is either absent or denoted by an asterisk. Please refer to Section 7.2 of the IWEM User's Guide (Limits on the Leachate
Concentration Threshold Value) for more details. A brief explanation of LCTV caps is given in this report after the detailed HBN results.
Detailed Results Based on MCL - No Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
MCL (mg/L)
0.005
0.006
0.005
DAF
2.2
2.2
LCTV
(mg/L)
0.011
0.014
0.011
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective ?
Yes
No
No
Detailed Results Based on MCL - Single Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
MCL (mg/L)
0.005
0.006
0.005
DAF
6.1
6.2
LCTV
(mg/L)
0.031
0.04
0.031
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective ?
Yes
Yes
Yes
Detailed Results Based on MCL - Composite Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
MCL (mg/L)
0.005
0.006
0.005
DAF
1 .90E+04
6.20E+05
LCTV
(mg/L)
0.5 (A)
1000(B)
1000(B)
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective?
Yes
Yes
Yes
Detailed Results Based on HBN - No Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
HBN (mg/L)
0.0016
0.0098
0.013
Exposure
Pathway & Effect
Inhalation Cancer
Ingestion Non-cancer
Ingestion Cancer
DAF
2.2
2.2
LCTV
(mg/L)
0.0036
0.023
0.029
Leachate
Cone . (mg/L)
0.01
0.03
0.02
Protective?
No
No
Yes
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
2 of 7
-------
Detailed Results Based on HBN - Single Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
HBN (mg/L)
0.0016
0.0098
0.013
Exposure
Pathway & Effect
Inhalation Cancer
Ingestion Non-cancer
Ingestion Cancer
DAF
6.1
6.2
LCTV
(mg/L)
0.0097
0.068
0.081
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective ?
No
Yes
Yes
Detailed Results Based on HBN - Composite Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
HBN (mg/L)
0.0016
0.0098
0.013
Exposure
Pathway & Effect
Inhalation Cancer
Ingestion Non-cancer
Ingestion Cancer
DAF
1 .90E+04
6.30E+05
LCTV
(mg/L)
0.5 (A)
1000(B)
1000(B)
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective?
Yes
Yes
Yes
CAPS & WARNINGS
A - The LCTV is capped by the Toxicity Characteristic Rule Exit Level (TC LEVEL) of the constituent.
B - The LCTV is capped by 1000 mg/L (EPA Policy).
C - The LCTV exceeds the cited solubility for this constituent.
D - The parent constituent LCTV is derived from the LCTV of a more conservative toxic daughter product(s).
E - The parent constituent does not have a RGC for this exposure pathway and effect, but the toxic daughter product(s) does. The LCTV of the parent is derived from
the LCTV of the toxic daughter product.
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
3 of 7
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Constituent Name
Benzene
CAS ID
71-43-2
Physical Properties
Property
Constituent Type
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
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
78.1134
1.8
0
0
0
1750
282
0.0325
0.0056
Data Source
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)
Reference Dose (mg/kg-day)
Reference Concentration (mg/mA3)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.005
0.0018
0.19
0.0016
0.06
0.055
0.027
Data Source
USEPA, 2000h
USEPA, 2001 b
CALEPA, 1999b
USEPA, 2001 b
CALEPA, 2000
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
4 of 7
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Constituent Name
Antimony
CAS ID
7440-36-0
Physical Properties
Property
Constituent Type
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
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
121.76
1.00E+06
Data Source
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)
Reference Dose (mg/kg-day)
Reference Concentration (mg/mA3)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.006
0.0098
0.0004
Data Source
USEPA, 2000h
USEPA, 2001 b
USEPA, 2001 b
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
5 of 7
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Constituent Name
Methylene Chloride (Dichloromethane)
CAS ID
75-09-2
Physical Properties
Property
Constituent Type
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
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
84.9328
0.93
0
0.001
0.6
1.30E+04
315
0.0394
0.0022
Data Source
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)
Reference Dose (mg/kg-day)
Reference Concentration (mg/mA3)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.005
1.5
0.013
10
0.028
0.06
3
0.0075
0.0016
Data Source
USEPA, 2000h
USEPA, 2001 b
USEPA, 2001 b
USEPA, 1997a
USEPA, 2001 b
USEPA, 2001 b
USEPA, 1997a
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
6 of 7
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References
CalEPA. 1999b. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III. Technical Support Document for the Determination of Noncancer Chronic
Reference Exposure Levels. SRP Draft. Office of Environmental Health Hazard Assessment, Berkeley, CA. http://www.oehha.org/hotspots/RAGSII.html.
CalEPA. 2000. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III. Technical Support Document for the Determination of Noncancer Chronic
Reference Exposure Levels. Office of Environmental Health Hazard Assessment, Berkeley, CA. Available online (in 3 sections) at
http://www.oehha.org/air/chronic_rels/22RELS2k.html, http://www.oehha.org/air/chronic_rels/42kChREL.html,
http://www.oehha.org/air/chronic_rels/Jan2001 ChREL.html.
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July 2001.
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. 1997a. Health Effects Assessment Summary Tables (HEAST). EPA-540-R-97-036. FY 1997 Update. Office of Solid Waste and Emergency Response,
Washington, DC.
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. 2000h. Code of Federal Regulations, National Primary Drinking Water Regulations, CFR 40, Part 141, Section 32. www.epa.gov/safewater/regs/cfr141 .pdf.
USEPA. 2001a. 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.
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/
Calculated from inhalation unit risk factors from USEPA, 2001 b.
Tier 1 Evaluation Results Facility Name: Southern Industries Landfill Facility Type: Landfill 6/20/2002 7 of 7
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Tier 2 Evaluation Results
Recommendation:
Composite Liner
6/20/2002 5:12:46PM
Facility Type Landfill
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
Landfill Parameters
Parameter Value
Depth of base of the LF below ground surface (m) 0
Distance to well (m) 150
Landfill area (mA2) [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
Data Source
Default
Default
132
zxc
Data Source
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]
1 of 7
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Regional Soil and Climate Parameters
Parameter
Soil Type
Climate Center
No Liner Infiltration Rate (m/yr)
Clay Liner Infiltration Rate (m/yr)
Composite Liner Infiltration Rate (m/yr)
Recharge Rate (m/yr)
Value
Medium-grained soil (silt loam)
Greensboro NC
.3256
.0362
Monte Carlo
0.3256
Constituent Reference Ground-water Concentrations and Constituent Properties
Constituent Name
Acrylonitrile
RGC
(mg/L)
0.0002
RGC Based On Kd* (L/kg)
HBN - Ingestion, Cancer
"If 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
Daughter Constituent Reference Ground-water Concentrations and Constituent Properties
Parent Constituent
Acrylonitrile
Acrylonitrile
Decay Coeff* Leachate
(1/yr) Cone. (mg/L)
0.1
of the report.
RGC
Daughter Constituent . „ . RGC Based On
(mg/L)
Acrylamide 2.20E-05 HBN - Ingestion, Cancer
Acrylic acid [propenoic acid] 12 HBN - Ingestion, NonCancer
"If a site-specific value was entered by the user, it will be displayed here; otherwise
Detailed Results for Parent Constituents - No Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
2.4
the model used the constituent properties listed at the end
Decay Coeff.*
Kd*(L/kg) (*/vr)
of the report.
LCTV RGC
(mg/L) Selected RGC (mg/L)
4.11E-05(D) HBN -Ingestion, Cancer 2.20E-05
90th %tile Exp.
Cone. (mg/L) Protective?
0.0413 No
Detailed Results for Parent Constituents - Clay Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
13
LCTV RGC
(mg/L) Selected RGC (mg/L)
0.0003 (D) HBN - Ingestion, Cancer 2.20E-05
90th %tile Exp.
Cone. (mg/L) Protective?
0.0075 No
Detailed Results for Parent Constituents - Composite Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
2.40E+04
LCTV
(mg/L)
4.32
Selected RGC
HBN - Ingestion, Cancer
RGC
(mg/L)
2.20E-05
90th %tile Exp.
Cone. (mg/L)
4.10E-06
Protective?
Yes
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
2 of 7
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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)
2.5
2.4
LCTV
(mg/L)
5.50E-05
28.8
Selected RGC
HBN - Ingestion, Cancer
HBN - Ingestion, NonCancer
RGC
(mg/L)
2.20E-05
12
90th %tile Exp.
Cone. (mg/L)
0.0539
0.0562
Protective?
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)
17
NA
LCTV
(mg/L)
0.0004
NA
Selected RGC
HBN - Ingestion, Cancer
All Available
RGC
(mg/L)
2.20E-05
90th %tile Exp.
Cone. (mg/L)
0.008
NA
Protective?
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 .OOE+30
NA
LCTV
(mg/L)
1000
NA
Selected RGC
HBN - Ingestion, Cancer
All Available
RGC
(mg/L)
2.20E-05
90th %tile Exp.
Cone. (mg/L)
0
NA
Protective?
Yes
See No Liner
CAPS & WARNINGS
A - The LCTV is capped by the Toxicity Characteristic Rule Exit Level (TC LEVEL) of the constituent.
B - The LCTV is capped by 1000 mg/L (EPA Policy).
C - The LCTV exceeds the cited solubility for this constituent.
D - The parent constituent LCTV is derived from the LCTV of a more conservative toxic daughter product(s).
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
3 of 7
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Constituent Name
Acrylonitrile
CAS ID
107-13-1
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
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
Data Source
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)
Reference Dose (mg/kg-day)
HBN-lngestion, Cancer (mg/L)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
HBN-lnhalation, Non-Cancer (mg/L)
Reference Concentration (mg/mA3)
HBN-lnhalation, Cancer (mg/L)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.025
0.001
0.0002
0.54
0.038
0.002
0.001
0.24
Data Source
USEPA, 1997a
USEPA, 1997a
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
4 of 7
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Constituent Name
Acrylamide
CAS ID
79-06-1
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
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
71 .0786
-0.989
31.5
0.018
0
6.40E+05
337
0.0397
1.00E-09
Data Source
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)
Reference Dose (mg/kg-day)
HBN-lngestion, Cancer (mg/L)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
HBN-lnhalation, Non-Cancer (mg/L)
Reference Concentration (mg/mA3)
HBN-lnhalation, Cancer (mg/L)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.0049
0.0002
2.20E-05
4.5
5.1
4.6
Data Source
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
5 of 7
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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) (mL/g)
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 .OOE+06
325
0.0378
1.17E-07
Data Source
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)
Reference Dose (mg/kg-day)
HBN-lngestion, Cancer (mg/L)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
HBN-lnhalation, Non-Cancer (mg/L)
Reference Concentration (mg/mA3)
HBN-lnhalation, Cancer (mg/L)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
12
0.5
15
0.001
Data Source
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
6 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. 1997a. Health Effects Assessment Summary Tables (HEAST). EPA-540-R-97-036. FY 1997 Update. Office of Solid Waste and Emergency Response,
Washington, DC.
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. 2001a. 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.
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/
Calculated from inhalation unit risk factors from USEPA, 2001 b.
Tier 2 Evaluation Results Facility Name: Facility Type: Landfill 6/20/2002 7 of 7
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