OSWER Models Study:
   Promoting Appropriate Use of Models
in Hazardous Waste / Superfund Programs
                   PHASE I

                 FINAL REPORT
                  May 26,1989


            Information Management Staff
      Office of Program Management and Technology
      Office of Solid Waste and Emergency Response

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          OSWER Models Study:
   Promoting Appropriate Use of Models
in Hazardous Waste / Superfund Programs
                   PHASE I

                 FINAL REPORT
                  May 26,1989


            Information Management Staff
      Office of Program Management and Technology
      Office of Solid Waste and Emergency Response

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               ACKNOWLEDGEMENT
      The OSWER Information Management Staff (IMS) wishes
to thank all those who have contributed to this effort, especially
members of the Hazardous Waste / Superfund Research
Committee, OSWER's Technology Staff, the Office of Solid
Waste, the Office of Emergency and Remedial Response, the
Office of Air Quality Planning and Standards, EPA Regions ffl
and V, Office of Research and Development (ORD) Headquarters
offices and ORD laboratories in Athens, GA, Ada, OK,
Cincinnati, OH, and Research Triangle Park, NC. American
Management Systems, Inc. (AMS) assisted OSWER IMS in
preparing this report. AMS collected information, conducted
interviews with study participants, and provided analytical
support throughout the study. AMS services were provided
under Contract No. 68-01-7281.

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                      OSWER Models Study--
             Promoting Appropriate  Use of Models
          In Hazardous Waste / Suoerfund Programs
                           Table of Contents
                                                                  Page
    Executive Summary	i
1.   Background and Methodology	:	1-1
    1.1. Purpose  	1-2
    1.2. Project Plan	1-3
    1.3. Project Activities	1-4
2.   Overview of the Modeling Environment	2-1
    2.1. Scope and Size	2-1
    2.2 Key Research Organizations and Modeling Centers	2-3
    2.3. Computing Environment	2-5
    2.4. Model Development, Verification, and Validation	2-6
    2.5. Model Selection and Application	2-8
    2.6. Levels of Usage	2-9
    2.7. User Support	2-10
3.   Modeling Environment Category Descriptions 	3-1
    3.1. Ground Water Modeling	3-2
    3.2. Exposure Assessment Modeling	3-12
    3.3. Air Dispersion Modeling	3-17
    3.4. Modeling for Hazardous Waste Engineering	3-23
    3.5. Surface Water Modeling	3-25
    3.6. Drinking Water Modeling	3-28

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                        Table of Contents (cont'd)
                                                                    Page
4.   Review of Management Issues	4-1
    4.1.  Importance of Modeling	4-2
    4.2.  Need for Guidance	4-4
    4.3.  Model Development, Calibration,
         Verification, and Validation	4-6
    4.4.  Hardware and Software	4-8
    4.5.  Model Selection and Application	4-9
    4.6.  User Support Organizations and Networks	4-10
5.   Recommendations
    5.1.  Task Area 1:  Initiation, Additional Studies,
         and Preparation of Management Plan	5-1
    5.2.  Task Area 2:  Development of Guidance	5-4
    5.3.  Task Area 3:  Establishment of User Support Networks	5-6
Appendix A:  Interview Guide	A-l
Appendix B: Interview List.	B-l
Appendix C: Bibliography	C-l
Appendix D: OSWER Models Inventory - Abbreviated	D-l

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Executive Summary
    During the 1970s and 1980s, there has been a steady increase in
the frequency with which computerized, mathematical models are
used at EPA by program office staff as tools for supporting
regulatory decision-making.  Models offer valuable new capabilities
and significantly increase predictive power under conditions of
incomplete information or uncertainty.  On the other hand, as
model development and usage proliferates, senior managers and
technical staff are concerned about the difficulty in ensuring that
models will be applied in appropriate and valid ways. Many
models now run on Agency-standard personal computers and are
readily available to non-experts with  no formal training in model
development or application.  At EPA, these concerns are
underscored by recent cases in which  the application of a model has
been challenged in court (e.g., McLouth Steel Products Corp. v.
Thomas. 1987).

    Many of the model management issues affecting the Agency
as a whole are particularly relevant to the programs managed by
the Office  of Solid Waste and Emergency Response (OSWER) and
mandated  by  the Resource Conservation and  Recovery Act (RCRA)
and the Comprehensive  Environmental Response Compensation
and Liability Act (CERCLA).

    The Information Management Staff in OSWER's Office of
Program Management and Technology (OPMT) has conducted this
Models Study in order to develop  a better understanding of the
scope and  size of the modeling environment of hazardous waste /
Superfund (HW/SF) programs,  to identify associated management
issues, and to prepare a set of recommendations for promoting the
appropriate use of models. The scope of the study is on computer-
based mathematical models used to predict or simulate
environmental effects.  Physical models are not included in the
study, and there is limited emphasis on management and
economic (i.e., "cost") models. The purpose of this report is to
describe the OSWER modeling  environment, to identify
management issues, and to make recommendations for future
improvement initiatives.

    The Information Management Staff coordinated this project
with the members of the HW/SF  Research Subcommittees.  Those
members have provided  sources of information and comments on
the draft findings, issues, and recommendations.  The project team
collected its baseline information  through in-person and telephone
interviews at EPA Headquarters, Regional Offices, and several
Office of Research and Development (ORD) research facilities.
During these information gathering activities, the project team

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                         compiled the OSWER Models Library, a collection of over seventy
                         reference documents, and the OSWER Models Inventory, a
                         computerized database containing descriptive information on over
                         300 models.

                             The OSWER modeling environment is comprised of several
                         heterogeneous modeling categories focusing on different
                         environmental media, processes, and pathways. The six categories
                         are: Ground Water, Exposure Assessment, Air Dispersion, Surface
                         Water, Hazardous Waste Engineering, and Drinking Water.  The
                         following observations are presented in this report:

                         •   Scope and Size. There are more than 310 models of interest to
                             hazardous waste / Superfund programs.

                         •   Key Research Organizations and Modeling Centers. The
                             primary organizations involved in development are the EPA
                             Office of Research and Development (especially through
                             research laboratories in Ada, Athens, Cincinnati, and Research
                             Triangle Park), EPA program offices (e.g., OSW, OERR, OPMT,
                             OAQPS), universities and affiliated academic institutions (e.g.,
                             International Ground Water Modeling Center), and private
                             scientific and engineering firms.

                         •   Computing Environment.  The majority of existing models
                             are written in FORTRAN.  Older models run primarily  on
                             mainframes or minicomputers, but many have been adapted
                             to run on microcomputers.  Newer models are primarily
                             targeted for delivery on microcomputers or workstations,
                             using a variety of languages and tools.

                         •   Development, Verification, Validation.  Currently, efforts for
                             model development are evenly distributed between equation
                             development, software development, model modification,
                             and the combination of existing models. This is in contrast to
                             the past, when the major emphasis in modeling was on
                             equation development and programming. Model verification
                             and validation are topics of much  discussion and some
                             controversy in the modeling community.  There are no
                             universally accepted definitions of model verification and
                             validation.

                         •   Model Selection and Application. Model selection requires
                             expert knowledge of both the process to be modeled and the
                             models available. Model application is the process of using a
                             particular model to make predictions and conduct analyses.
                             Depending on how well the model fits the scenario,
                             validation steps are often repeated as part of die model
                             application process. As a model becomes widely distributed
                             and applied in different scenarios,  it becomes difficult to keep
                             track of its performance under different circumstances.

If

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                         •   Levels of Usage. This study has not been able to determine
                             the exact frequency of model usage. There are no tracking
                             systems  to monitor actual usage in the field, but the facts to
                             support  the claim that model usage is widespread and growing
                             steadily  include: (1) thousands of copies of models are being
                             requested yearly, (2) the availability of microcomputers and
                             microcomputer based models, (3) the scope and emphasis of
                             OSWER programs. Ground water, exposure assessment, and
                             engineering models appear to be the types most commonly
                             used for OSWER programs

                         •   User Support. The need for user support has been recognized
                             by the modeling community, but a fundamental lack of
                             human resources limits the quality of support services.
                             Mechanisms such as technology transfer activities, training
                             seminars, electronic bulletin boards, user groups, and
                             clearinghouses for documentation are available to most
                             modelers, but flexible, application-specific support and
                             consultation with a modeling expert are needed in many
                             instances.

                             Based on the information gathered in describing the OSWER
                         modeling environment and following discussions at several
                         meetings with members of the Hazardous Waste / Superfund
                         Research Subcommittees from OSWER and ORD, the project team
                         identified and analyzed six major management issues:

                         •   Issue #1:  What is the relative  importance of models in
                                       supporting hazardous waste / Superfund program
                                       activities?

                         •   Issue #2:  Is formal guidance on modeling necessary? If so,
                                       how should the guidance be developed and by
                                       whom?

                         •   Issue #3:  How should OSWER and ORD manage model
                                       development, calibration, verification, and
                                       validation?

                         •   Issue #4:  What types of standards should be imposed on
                                       hardware and software?

                         •   Issue #5:  How should model selection and application be
                                       occurring in  the field?

                         •   Issue #6:  What types of user support organization and
                                       products  should be created for model users?

                             The analysis of these issues and discussions with OSWER and
                         ORD members of the Hazardous Waste / Superfund Research
                         Subcommittee generated a series of alternative action items.  The
                         project team  developed a recommended action plan  that organizes
'"                       the various action items into a manageable sequence and

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                         recognizes the importance of obtaining endorsement from top
                         management in OSWER and ORD in order to carry out a multi-
                         year, interdisciplinary improvement effort. Three major task areas
                         are proposed:

                         •   Task Area 1:  Initiation/ Additional Study/ and Preparation
                             of Management Plan. This task area includes briefings for
                             OSWER and ORD senior management on results of the
                             Models Study/ development of a detailed management plan
                             for modeling improvements/ conducting additional studies of
                             the legal and policy issues related to modeling/ and gathering
                             more in-depth information on model usage in  the Regional
                             offices.  The overall purpose of the tasks is to educate senior
                             managers and obtain top-level endorsement for future plans/
                             including commitment of resources/ and clarification of roles
                             and responsibilities.

                         •   Task Area 2: Development of Guidance for Modeling. This
                             task area covers the development of the various types of
                             guidance necessary for modeling in Hazardous Waste /
                             Superfund Programs. Three guidance products are specified:
                             (a) guidance on model development/ validation/ and
                             verification/ focused on the concerns of model developers and
                             addressing peer review and the relationship between
                             validation and Data Quality Objectives (DQO); (b) reviews of
                             the current and future computing approaches for models/
                             including periodic 'Technology Updates" and suggestions for
                             maintaining and distributing modeling software; (c) guidance
                             on selection and application of models/ focused on model
                             users in the Regional offices.

                         •   Task Area 3:  Establishment of User Support Network for
                             HW/SF Modeling. Several new user support mechanisms
                             and/or organizational relationships are called for.  Regional
                             Modeling Groups (RMGs) are envisioned as a service bureau in
                             each Region/ providing a central  pool of modeling  expertise.
                             RMG staff will have a portion of their time dedicated to
                             fulfilling their RMG roles and will communicate directly with
                             the ORD Modeling Centers and the OSWER Modeling
                             Support Group. The ORD Modeling Centers will be  the primary
                             source of scientific and technical  support for Regional model
                             users. They will have a media orientation, reflecting the
                             strengths of different labs in different media/ and they will
                             develop models, modify codes, add enhancements, conduct
                           .  training courses, consult with users about specific modeling
                             applications, and pro-actively monitor the field performance
                             of the models they are supporting. The OSWER Modeling
                             Support' Group will have a dual mission: first, it will be
                             primarily responsible for managing the development and
                             dissemination of guidance materials on modeling;  second, it
                             will provide RMGs and other users with specific policy and
jv                           legal advice on model applications. This includes reporting

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    on significant policy and legal events that affect the future use
    of models (e.g., court cases, new regulations).

    The anticipated timeline for the action plan covers the latter
half of FY '89 through FY '92. Preliminary resource estimates
include a minimum of 15 FTEs and at least $300K of extramural
funds. Both the timeline and the resource requirements will be
specified in greater detail in the OSWER-ORD Models
Management Plan which will be developed under Task Area 1 of
the Action Plan.

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Section  1.            Background and Methodology
                             Senior EPA managers and Agency support groups such as the
                         Science Advisory Board (SAB) have recognized the increasing
                         frequency with which program office staff are using computerized,
                         mathematical models to predict environmental effects and make
                         regulatory decisions.  Several major factors are contributing to this
                         trend, including:

                         •   It is either technically infeasible or too costly to gather
                             complete data for some of EPA's newer, broad-ranging
                             programs, and the use of models helps to support decision-
                             making under conditions of incomplete information or
                             uncertainty.

                         •   A larger proportion of environmental scientists and engineers
                             receive training in mathematical forrmilation and solution
                             techniques and are actively seeking ways to apply these
                             methods to EPA's regulatory programs.

                         •   Developments in computer technology have increased the
                             number of tools available to the modeler, made it easier to
                             develop models, significantly increased their speed, and added
                             to output options (e.g., graphics, maps). In particular, the
                             wider availability and lower cost of microcomputers has
                             eliminated many of the barriers between modelers and
                             programmers and between programmers and end users.
                             Computing technologies such  as artificial intelligence and
                             supercomputers have emerged from research labs and are
                             now being used to solve modeling problems.

                         •   Scientific research on environmental processes during the
                             past several decades has steadily advanced modelers'
                             knowledge of physical and chemical processes and their ability
                             to predict the transport and fate of many pollutants.

                             As the number of models increases and users become a more
                         diverse group, with widely varying levels of knowledge and
                         experience, it becomes increasingly difficult to ensure that models
                         are used appropriately. At EPA, these concerns are underscored by
                         cases in which the application of a model has been challenged in
                         court. An example is the 1988 court decision in McLouth Steel
                         Products Corp. v. Thomas. No. 87-1049, that EPA failed to provide
                         sufficient public notice and opportunity for comment on its plan to
                         use the VHS model (Vertical Horizontal Spread model, EPA 1985)
                         to grant or deny a de-listing petition under the RCRA program.

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                             SAB's Environmental Engineering Committee has recently
                        produced a "Resolution on the Use of Mathematical Models for
                        Regulatory Assessment and Decision-Making." It identifies critical
                        issues that must be addressed in order to improve the use of
                        models throughout EPA.  Included in the resolution are calls for
                        creating a central modeling coordination group to provide
                        guidance in model selection and validation; ensuring that EPA
                        hires and supports larger numbers of engineers and scientists with
                        appropriate model development and application skills; ensuring
                        that a systematic model management process is in place to respond
                        to the introduction of new computer technologies and modeling
                        approaches; and establishing proper peer review procedures at
                        various levels.
Section  1.1.          Purpose
                             In the Office of Solid Waste and Emergency Response
                          (OSWER), the programs mandated by RCRA and CERCLA
                          present unique opportunities to use models to improve
                          regulatory decision-making.  Under RCRA, for example,
                          engineering models can help assess the costs and benefits of
                          alternative containment approaches at Treatment, Storage, and
                          Disposal facilities (TSDs). At Superfund sites, models can be used
                          to predict transport and fate of pollutants in multiple media —
                          ground water, air, surface water, and drinking water.  For these
                          types of analyses, decision makers can rely on models to provide
                          predictive information and improve their understanding of the
                          environmental processes under consideration.

                             However, even though RCRA and CERCLA programs present
                          many opportunities for using models, there are no standards or
                          guidelines on when and where specific models should be used.
                          The Office of Air Quality Planning and Standards (OAQPS) is an
                          example of a program office that has developed guidelines for
                          applying models to specific types of regulatory decisions. One
                          modeling challenge for OSWER is to ensure that models are
                          being applied appropriately and consistently, while recognizing
                          that there may be hundreds of different scenarios and site-specific
                          issues affecting model usage under RCRA and CERCLA. In
                          addition,  OSWER must address other modeling challenges, such
                          as providing adequate technical support, delivering sufficiently
                          powerful computers to model users, and training program office
                          staff.

                             The Information Management Staff in OSWER's Office of
                          Program Management and Technology initiated this models
                          study in October, 1988, in order to develop a better understanding
1-2                       of the scope and size of the modeling environment for hazardous

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                           waste / Superfund (HW/SF) programs, and to identify associated
                           management issues. Project kick-off meetings were held with
                           OSWER and ORD members of the Hazardous Waste / Superfund
                           Research Committee. One of the products of these meeting was
                           the development of the following project charter:

                                   For the purposes of this modeling study, the following
                              definition for the term model, as set forth b\j the American
                              Society for Testing and Materials (ASTM, 1984) in a
                              protocol for evaluating environmental chemical-fate
                              models, will apply: A model is an assembly of concepts in
                              the form of a mathematical equation  that portrays
                              understanding of a natural phenomenon.

                                   This study is concerned with models that are used by
                              the Office of Solid Waste and Emergency Response to
                              support programmatic decisions and compliance and
                              enforcement actions.  In particular, the focus is on models
                              that use computer software to perform numerical
                              computations and  prepare estimates based on physical
                              laws, probabilities, and statistics; the results of these models
                              help predict environmental or scientific effects.  The scope of
                              the study may extend to economic and management
                              models (e.g., cost recovery, workload estimation),  but
                              these are not the highest priority. Physical models  will not
                              be addressed  by the study.

                              The purpose of this report is to describe the OSWER modeling
                          environment, review  various  management issues  associated with
                          modeling in HW/SF programs, and present a recommended action
                          plan for promoting appropriate model use.
Section 1.2.          Project  Plan
                               The project plan for the Models Study included three major
                          tasks:

                          •  Task 1 — conducting interviews, reviewing reference materials,
                             and conducting analysis to accurately and concisely describe the
                             current modeling environment for hazardous waste /
                             Superfund programs;

                          •  Task 2 — incorporating feedback received on the modeling
                             environment description and working with ORD and OSWER
                             managers to identify and prioritize management issues
                             associated with model development, usage, and support;

1-3

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                           Task 3 - preparing a final report and action plan specifying
                           future activities designed to further promote the efficient and
                           effective use of models to support OSWER program activities.
Section  1.3.         Project Activities
                             Two kick-off meetings were held at the end of October, 1988, to
                        initiate the project. The first was attended by ORD subcommittee
                        members of the Hazardous Waste / Superfund Research
                        Committee and project team members from the OSWER
                        Information Management Staff and American Management
                        Systems, Inc.,.  The second meeting was attended by OSWER
                        subcommittee members of the Committee and the project team.
                        The scope and priorities for the modeling study were key issues at
                        both meetings. Participants stressed the need to clarify terms and
                        establish basic definitions. As a follow-up activity, the project team
                        prepared the project charter presented above in Section 1,2.

                             Following the kick-off meetings, the project team collected
                        comments from the OSWER and ORD subcommittee members
                        and gathered information on important points of contact identified
                        during the meetings.  A flexible Interview Guide (see Appendix A)
                        was prepared in order to ensure consistency for the interviews but
                        allow the project team to explore special topics in-depth with the
                        interviewee as appropriate.  Beginning in November, 1988, and
                        through February 27,1989, the project team conducted forty-nine
                        in-person and three telephone interviews at EPA Headquarters,
                        Regional Offices, and several ORD research facilities, located in the
                        cities shown in Exhibit 1.3-1. Appendix B lists the names, dates,
                        and locations of the interviews.

                             During the interviewing sessions and through  other
                        information gathering activities, the project team has also
                        compiled the OSWER Models Library, a collection of over seventy
                        reference documents  such as model user's guides, modeling
                        studies, and research papers. Appendix C contains the current
                        bibliography for the OSWER Models Library.  Another product
                        developed for this project is the OSWER Models Inventory, a
                        database of descriptive information on over 300 models of interest
                        for HW/SF programs. Appendix D confirms expects for the
                        OSWER  Models Inventory.

                             At the conclusion of the information gathering phase in
                        March, 1989, the project team issued a draft report entitled
                        "Description of the Hazardous Waste /  Superfund Modeling
                        Environment."  That  report described the OSWER modeling
                        environment, providing information on past and present
                        modeling activities and identifying over 300 models of interest to

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                         HW/SF programs. The information presented in that report has
                         now been updated to incorporate comments received from
                         document reviewers. Much of the content of that report is
                         reprinted Sections 2 and 3 of this document.
                                                                           Philadelphia, PA

                                                                           Washington, D.C.
Indianapolis, IN •
     Cincinnati, OH •
                                         Exhibit 1.3-1.  Interview Locations
                             On April 4th, the project team met with members of the
                         HW/SF Research Subcommittees from OSWER and the Office of
                         Research and Development (ORD). The purpose of this meeting
                         was to review the draft report cited above and to begin identifying
                         management issues for modeling.  The project team prepared a
                         Review of Management Issues which discusses six major issue
                         areas in a logical sequence.  For each of the issue areas, this section
                         provides a re-cap of key findings related to the issues, presents a
                         preliminary conclusion/resolution for the issue, and identifies
                         several alternative action items. This review is now contained in
                         Section 4 of this document.

                             Following the April 4th meeting, the project team met again
                         with members of the ORD and OSWER HW/SF Research
                         Subcommittees on April 25th to discuss the management issues
                         identified earlier and prepare the recommendations now contained
                         in Section 5 of this document. The section on Recommendations
                         organizes the various issues and related action items into a concise
                         action plan for achieving the desired improvements for models
                         management and usage.  It also outlines a suggested sequence of
                         events and describes responsibilities and specific products.
1-5

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                             Sections 4 and 5 are based primarily on the discussions that
                         took place at the April 4th and 25th meetings, and the project
                         team's subsequent analysis of those issues. Other sources of input
                         include individual meetings with key OSWER and ORD managers
                         and information gathered  at a meeting of the Science Advisory
                         Board held on April 6th-7th to discuss Agency-wide modeling
                         issues.
1-6

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Section 2.
Overview of the  Modeling Environment
Section  2.1
                             This section provides a high-level, comparative overview of
                         the HW/SF modeling environment.  In keeping with the purpose
                         of this report, the information presented here and in Section 3 is
                         descriptive, not evaluative; it is the basis for the review of
                         management issues and recommendations presented in Sections 4
                         and 5.

                             The modeling environment includes several heterogeneous
                         modeling categories focusing on different environmental media,
                         processes, and pathways. The major categories comprising the
                         modeling environment are:

                         •   Ground Water Modeling

                         •   Exposure Assessment Modeling

                         •   Air Dispersion Modeling

                         •   Surface Water Modeling

                         •   Modeling for Hazardous Waste Engineering

                         •   Drinking Water Modeling.

                              The organization of modeling activities into these six
                         categories generally mirrors the way modeling activities are
                         organized within ORD and the way information was presented to
                         the project  team. However, these categories are not mutually
                         exclusive, and there are numerous models that are relevant to
                         multiple categories (e.g., exposure assessment models focused on
                         surface water pathways).  For a more detailed description of the
                         categories, see the individual, category-by-category sub-sections in
                         Section 3.
Scope and Size
      2-1
    This study has so far identified 311 models of interest to
hazardous waste / Superfund programs. This is a conservative
estimate, subject to several qualifiers. First, the estimate includes
only models that fit the definitions and focus for this project — i.e.,
computerized mathematical models used to make predictions
based on physical laws, probabilities, and statistics. Desk-top

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                   procedures are not included.  Second, the estimate includes mostly
                   EPA related models identified through the interviews (see
                   Appendix B for a list of names and dates) and reviews of reference
                   documents listed in the Bibliography (Appendix C).  A
                   comprehensive survey of academic institutions, government
                   agencies, and industrial organizations was not conducted.  Finally,
                   because no tracking systems exist to monitor actual usage and
                   model validation experiences in the field, models included in this
                   total are only those cited by the interviewees as having been used
                   in hazardous waste / Superfund programs  or those whose
                   functional description matches with one or more OSWER program
                   requirements.  The total universe of all possible models could be
                   two or three times the initial estimate, depending on the
                   definitions and criteria used.

                       Among the universe of available models, a comparatively
                   small subset appears to be used intensively by OSWER program
                   staff at EPA Headquarters and in the Regions.  For instance, of the
                   twenty eight air dispersion models identified, one model in
                   particular, the Industrial Source Complex (ISC) model, is used
                   much more frequently than other air models because its
                   orientation and assumptions are more compatible with RCRA and
                   CERCLA program requirements.

                       As show in Exhibit 2.1-1, the largest single category of models
                   is ground water models, numbering over 240 and accounting for
                   nearly eighty percent of the total model inventory. None of the
                   other model categories contains more than  30 models. In terms of
                   scope, models exhibit a wide range of variability across several
                   dimensions:

                   •   Temporal  scales vary from minutes and seconds to decades
                       and even millennia (e.g., for some ground water models).

                   •   Spatial scales vary from molecular sizes (e.g., for models of
                       chemical reactions) to hundreds of miles (e.g., for air
                       dispersion models).

                   •   Numerical methods  vary from simple analytical solutions to
                       complex,  multidimensional numerical simulations.

                   •   Models predict outcomes for events ranging from chemical
                       interactions to biological processes to physical movement of
                       particles and liquids through various media. Models  also
                       address engineering problems (e.g., for landfills, incinerators).

                   •   Models can be used to support decision-making for a wide
                       range of programmatic activities — from permitting to
                       compliance checking to enforcement to remediation.
2-2

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                              Hazardous
                                Waste
                       Drinking Engineering
                        Water
                                                                 Exposure
                                         Air Dispersion,
                                           Emissions
                                             27
                                              Surface
                                              Water
                                                21
            Exhibit 2.1-1.  Number of models in each category
Section  2.2.
Key Research Organizations and Modeling
Centers
    ORD laboratories are the lead EPA organizations for research
and model development. Individual laboratories focus on specific
categories of models — for example, the Robert S. Kerr
Environmental Research Laboratory (RSKERL) is the lead lab for
ground water research and modeling,  and the Environmental
Research Laboratory at Athens (ERL-Athens) is the focal point for
surface water models and a variety of exposure assessment models.
Some of the labs have established specialized modeling support
centers.  RSKERL works closely with the International Ground
Water Modeling Center, which is part of the Holcomb Research
Institute at Butler University in Indianapolis, Indiana. ERL-
Athens has created the Center for Exposure Assessment Modeling
(CEAM). CEAM is a matrix organization that has established
relationships with researchers, modelers, and technical support
staff at Athens  and other parts of ORD. Several of the labs are
involved in more than one type of modeling. Exhibit 2.2-1 shows

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                    the various relationships between model categories and ORD labs.
                    The specific types of modeling activities conducted by these labs is
                    described in more detail in Section 3.
                   c
                      Modeling Categories
 Ground Water Modeling
                                  ORD Labs and Affiliates
                    I Exposure Assessment Modeling
                   c
                   c
                   c
                   c
 Air Dispersion Modeling
 Modeling for Hazardous
   Waste Engineering
 Surface Water Modeling
Drinking Water Modeling
                                   Robert S. Kerf ERL, Ada, and
                                    Holcomb Research Institute
                                   ERL-Athens and the Center for
                                   Exposure Assessment Modeling
  Air Research and Exposure
 Assessment Laboratory, RTF
 Risk Reduction Engineering
   Laboratory, Cincinnati
Environmental Monitoring and
   Systems Lab, Las Vegas
 Air and Energy Engineering
      Laboratory, RTF
                                            Exhibit 22-1

                        In addition to the ORD laboratories, there are a variety of
                    other organizations that directly or indirectly support modelers and
                    model users.  These include:

                    •   The OSWER Office of Program Management and Technology
                        (OPMT). One of OPMT's main modeling activities has been in
                        the area of ground water modeling, where it procured and
                        deployed the Ground Water Workstation in each of the ten
                        Regions. The workstation provides a pre-packaged set of four
                        models and  a limited set of other automated tools.  OPMT has
                        established a network of Technology Support Centers for
                        Remedial Project Managers (RPMs) and On-Scene
                        Coordinators (OSCs).  This effort includes the creation of the
                        Ground Water Forum, Engineering Forum, and Exposure
                        Assessment  Forum, designed to provide Superfund staff with
                        a convenient way to identify appropriate media or technology
                        experts.

                    •   The Office of Solid Waste (OSW).  OSW has been involved in
                        modeling to varying degrees over the past several years.  OSW
                        currently maintains a modeling oversight role and sponsors
                        some model development efforts within ORD. In addition,
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                             OSW is supporting an internal effort to develop a ground
                             water model called the EPA Composite Landfill Model.

                             The Center for Environmental Research Information (CERI).
                             CERI is an ORD organization based in Cincinnati, Ohio, that
                             supports technology transfer throughout the Agency by
                             producing and distributing technical reports and sponsoring
                             various types of seminars and training courses.  CERI is not
                             involved in model development directly, but can serve as a
                             distributor of models or documentation on models.  CERI has
                             agreed to provide this type of support for expert systems being
                             developed by the ORD. CERI also assists with the testing of
                             expert systems in various stages of development.

                             The Office of Toxic Substances (OTS).  OTS has supported the
                             development of GEMS, the Graphical Exposure Modeling
                             System. GEMS has been used by OSW for hazardous waste
                             incinerator regulations, unsaturated zone modeling, and
                             estimation of physical-chemical properties for waste
                             constituents.
Section  2.3.         Computing Environment
                            The computing environment consists of the hardware,
                        software, and peripheral equipment used to develop and run
                        models. As a group, modelers have no established forum for
                        discussing new product offerings and alternative computing
                        approaches, but there are common characteristics and trends in
                        computing for the various model categories. The following
                        observations about computing environments are applicable to all
                        modeling categories, unless noted otherwise:

                        •  The increasing availability and power of microcomputers has
                            had a major impact on model development and usage.  Most
                            modelers now use microcomputers for development and
                            target micros as their delivery platform.

                        •  DOS-compatible micros with math co-processors are now the
                            modeler's most common hardware unit. Other hardware
                            includes  Apple Macintoshes, Hewlett Packard
                            microcomputers, SUN workstations, VAX minicomputers,
                            and IBM mainframes.

                        •  No official software standard exists for models, but because of
                            its popularity and acceptance, FORTRAN has become a de facto
                            standard for some model developers. There is a high level of
                            interest in standardizing FORTRAN styles and selecting a
      2.5                   common version that will ensure portability across platforms

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                             (i.e., ANSI FORTRAN 77).  This "standard" has been
                             promoted for hydrologic models by the U.S. Geological in a
                             report entitled "FORTRAN 77 Coding Conventions and
                             Documentation Software" (USGS Open File Report, Kittle,
                             Runbe, and Flyn, 1986).

                        •   A variety of other programming languages are used as well,
                             including C, Pascal, and Basic. Some models draw upon  the
                             capabilities of software packages for managing data and
                             improving input and output features.  Packages include
                             dBASE, HyperCard, Lotus 1-2-3, and expert system shells.

                        •   Supercomputer technology is not an immediate priority  given
                             the current set of  research initiatives and model development
                             priorities. There are a few exceptions to this, for example in
                             the air programs, where issues such as acid rain and global
                             warming may necessitate the development of a new class of
                             large-scale computer models.

                             Even though modelers rely on the same basic hardware and
                        software tools for computing, they employ different model
                        development approaches  and place different degrees of emphasis
                        on software engineering issues.  User interfaces and model output
                        capabilities vary significantly from model to model. Models
                        provide widely varying levels of on-line help, ease of entry for
                        input values, and elegance of reports.  User interface issues are
                        resolved differently, depending on the sophistication of the model
                        and  the orientation of  the modeler. Some modelers have an  "anti-
                        menu" philosophy and assume the user will be a proficient
                        programmer with in-depth understanding of the internal workings
                        of the model.  In  some  cases, users must almost always consult
                        with the modeler on how to run the model. These types of models
                        typically run in batch mode on a mainframe while the inputs  are
                        entered through an editor or through programming statements.
                        At the other end  of the spectrum, there are model interfaces which
                        assume the user is a non-expert.  These models may have
                        interactive front-ends with on-line help.   Non-programmers  can
                        easily enter and edit input values. A few recently developed
                        models have incorporated window-based, icon-oriented front-ends.
Section  2.4.         Model Development,  Verification, and
                        Validation
                            The term "model development" refers to: (1) initial
                        development of equations; (2) programming of computer code; (3)
                        modification of existing model codes to handle new types of
                        calculations and simulations; and (4) linking of previously
      2-6               incompatible models. A significant amount of model

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                   development activity falls into the last two categories.  The
                   impetus for model development comes as a response to events
                   such as:

                   •   Outgrowths from primary research into some new area of
                       environmental science, hydrology, or other discipline (e.g., as
                       dissertation topics or EPA funded R&D projects)

                   •   Requirements for analyzing contamination problems at a
                       particular site or group of sites with a certain set of
                       distinguishing characteristics (e.g., in response to requests
                       from EPA Headquarters or Regional offices)

                   •   Needs for developing decision support tools in order to
                       implement  programs, created by new legislation or sets of
                       regulations (e.g., Clean Air Act, RCRA, CERCLA).

                       The primary organizations involved in development of  the
                   models identified in this study are the EPA Office of Research and
                   Development (primarily through its research, laboratories in Ada,
                   Athens, Cincinnati, and Research Triangle Park), EPA program
                   offices (e.g., OSW, OERR, OPMT, OAQPS), universities and
                   affiliated academic  institutions (e.g., the International Ground
                   Water Modeling Center (IGWMQ), and private scientific and
                   engineering firms.

                       A significant amount of introspective  analysis in the
                   modeling community has been devoted to  addressing model
                   development, selection, verification, validation, and application
                   issues.  Two recent  reports touching on these issues are
                   "Groundwater Modeling:  An  Overview and Status Report" and
                   "Selection, Application, and Validation of Environmental Models"
                   (for references, see the Bibliography in Appendix C). The Agency's
                   Exposure Assessment Group (EAG) has produced some suggested
                   definitions and guidance on model validation.  Ongoing  efforts
                   include work by a Technical Panel of the Risk Assessment Forum
                   to develop an Agency position on model validation in predictive
                   exposure assessments.  Despite these efforts, no hard and  fast rules
                   yet exist to govern model development and validation  processes.
                   The consensus among modelers is that this may not be desirable
                   anyway, as there are generally understood "rules of the road" and
                   principles of "good science."  Moreover, the model development
                   and validation process is strongly influenced by institutional
                   factors such as who is sponsoring the effort, what type of standards
                   are imposed by the  sponsor, and the intended use of the model.
                   For example, a researcher developing a model in art academic
                   setting (e.g., as a dissertation) may be subject to different peer
                   review requirements than a modeler working in an ORD
                   laboratory.

                       Controversy has sometimes surrounded the definition of
_ _                terms such as "verification" and "validation."  The general

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                    consensus is that verification and validation address two separate
                    questions: (1) For verification, "Are the numerical equations of the
                    model properly captured in the computer code?" and (2) For
                    validation, "Not is the model absolutely valid, but is it being
                    applied in a valid manner?" As implied by these questions,
                    verification is more limited to development of model codes,
                    whereas validation takes place both as part of the development
                    effort and as part of the application process. Modelers typically
                    conduct some type of validation as part of their development
                    effort, but this is often limited by a lack of resource availability.
                    The validation of a model using "real" field data can take years of
                    effort. For example, the exposure assessment model PRZM
                    underwent five years of validation efforts (at considerable cost) to
                    determine the valid boundaries for the application of the model.
Section  2.5.     Model Selection and Application
                         To select a model, an analyst must have information about
                    the particular site or scenario being studied, plus a thorough
                    understanding of the strengths and weaknesses of available
                    models.  A framework for model selection in the Superfund
                    program was developed in 1985 (see "Modeling Remedial Actions
                    at Uncontrolled Hazardous Waste Sites" in the Bibliography,
                    Appendix C). This framework is sufficiently general mat it could
                    be used by OSW with some minor modifications.

                         Responsibilities for model selection vary from case to case, but
                             an EPA project officer at Headquarters or in a Regional
                    office will be the final decision-maker. In some cases, contractors
                    make recommendations on appropriate models for a particular
                    analysis. EPA staff concur or disagree with these recommendations
                    based on their own experience or technical advice supplied by ORD
                    modeling experts. (ORD has developed a prototype expert system
                    which can help a modeler select the correct model).

                         Model application is the process of using a particular model to
                    make predictions and conduct analyses.  Depending on how well
                    the model fits the scenario, validation steps are often repeated as
                    part of the model application process. As a model becomes widely
                    distributed and applied in different scenarios, it becomes difficult to
                    keep track of its validity under multiple stresses.  Site-specific  .
                    models must be both calibrated and  validated every time they are
                    used at a new site.

                         Modelers and managers stress that there is no foreseeable way
                    to eliminate the possibility that models will be misused, but there
                    are ways to reduce the likelihood of this happening.  Ensuring that
 2-8               model users have the necessary knowledge and experience to

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                         properly apply the model and understand the limitations of its
                         predictive power is one crucial requirement for meeting this
                         challenge. In the Superfund program, the Regional Project
                         Managers (RPMs) rely on contractors to utilize models for various
                         parts of the Remedial Investigation / Feasibility Study (RI/FS)
                         process. RPMs do not need to be modelers, but they must have a
                         clear understanding of how to apply models appropriately and
                         know when an in-depth review of a modeling exercise is
                         warranted.
Section 2.6.          Levels of Usage
                             This study has not been able to determine the exact frequency
                         of model usage. There are no tracking systems to monitor actual
                         usage in the field, but several facts support the claim that model
                         usage is widespread and growing steadily:

                         •  During FY '88, CEAM distributed over over 1,500 copies of the
                             dozen models it manages; over 1,900 copies were distributed
                             in FY '87.

                         •  The  increasing availability of microcomputers in the field and
                             the trend toward micro-based models has significantly reduced
                             entry barriers. OSWER's Ground Water Workstation
                             provides a readily accessible modeling tool for all ten Regional
                             offices.

                         •  The  scope of OSWER programs and the growing emphasis on
                             exposure- and risk-based decision-making make modeling the
                             only feasible course of action in many cases. Monitoring can
                             be too costly and take too long.

                             Even though model usage as a whole may be on the rise, the
                         usage of models by personnel in the Regional offices tends to be
                         restricted by a lack of time, computer availability, training, and
                         other  resource issues.

                             Actual usage levels vary significantly from Region to Region
                         and across media. Ground water, exposure assessment, and
                         engineering models are the types most commonly used for
                         OSWER programs.  Although modeling  growth is difficult to
                         quantify, exposure modeling is probably the most rapidly
                         expanding category.
      2-9

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Section  2.7.         User Support
                            Numerous mechanisms are in place to support model users,
                        including:

                        •  Technology transfer activities (e.g., the OSWER Technology
                            Support Project for RPMs and OSCs, which includes the
                            establishment of groups such as the Ground Water Forum
                            and Engineering Forum)

                        •  Periodic training seminars and short courses (e.g., ground
                            water modeling courses sponsored by the Ada lab, short
                            courses taught by IGWMC)

                        •  Electronic bulletin boards (e.g., the OSWER bulletin board at
                            Headquarters, the CEAM bulletin board in Athens, and the
                            UNAMAP bulletin board in RTF)

                        •  Clearinghouses  for documentation (e.g., the CERI, CEAM, and
                            IGWMC).

                            Despite the availability of this type of support, there is a
                        limited amount of coordination among the different activities.
                        Users often have difficulty determining where to go first for
                        various types of support.

                            The most pressing user support needs can be directly linked to
                        human resource issues. In conjunction with the installation of the
                        Ground Water Workstation, some Regions have established
                        dedicated modeling support groups, but other Regions have no
                        staff members devoted to modeling and very few staff with
                        modeling experience. Most Regional RCRA and CERCLA program
                        staff have heavy demands on their time (e.g., some RPMs manage
                        thirty or more  sites simultaneously) and have no time to devote to
                        developing additional modeling expertise. Often, because of their
                        busy schedules, those who could benefit most from additional
                        training on modeling are the least likely to attend  training when it
                        is offered. Managers in the Regions are sometimes reluctant to
                        allow their staff to attend modeling courses because it takes
                        valuable time away from day-to-day priorities.
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Section  3.            Modeling Environment Category
                         Descriptions
                             This section provides individual descriptions for the six
                         modeling categories identified in this study:

                         • Ground Water Modeling

                         • Exposure Assessment Modeling

                         • Air Dispersion Modeling

                         • Surface Water Modeling

                         • Modeling for Hazardous Waste Engineering

                         • Drinking Water Modeling.

                             These descriptions offer an in-depth look at the types of
                         modeling and support activities being conducted by the various
                         EPA Headquarters, ORD research laboratories, and Regional offices.
                         Each description covers the size and scope of the modeling
                         category, the relationship of these types of models to OSWER
                         programs, the key organizations and modeling centers, and
                         individual findings on model development, usage, and support.

                             The organization of modeling activities into these six
                         categories generally mirrors the way modeling activities are
                         organized within ORD and the way information was presented to
                         the project team.  In order to minimize confusion and avoid
                         double counting, models are assigned to only  one of the categories,
                         although there are cases where a particular model could be
                         included in multiple categories.  The Exposure Assessment and
                         Engineering categories, in particular, represent modeling disciplines
                         and cut across media such as surface water, drinking water, and air.
                         Later phases of this project will address the need to develop more
                         precise categories.

                             The documents referenced by footnotes in this section can be
                         found in the Bibliography in Appendix C. The convention used
                         for footnotes is  (Xn), where X is a one-letter code for the model
                         category and n is a sequence number.
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Section 3.1.
Ground Water  Modeling
Size and Scope
                            Ground water modeling is the largest single category of
                        models used to support OSWER program activities.  Estimates vary
                        depending on how they are grouped and defined, but
                        conservatively, there are over 250 ground water models that are
                        related to OSWER requirements or have been used by OSWER
                        program staff.  Ground water modeling is also one of the most
                        dynamic categories in terms of development of new model codes
                        and the increasing number of cases in which models are being used
                        to support programmatic decisions.
                            A major reason for the size of this category is the
                        of the medium itself. As Exhibit 3.1-1 shows, ground water models
                        simulate many different relationships between ground water and
                        other elements of the hydrosphere.
                                                                             •vaporatloi
                                       U DW A ER f Zft N  /Q UJ F
3-2
                     Exhibit 3.1-1 (reprinted from G10)

    Added to this set of relationships are the numerous temporal
and spatial scales which the models address. Spatial scales range
from less than a nanometer to hundreds of kilometers. Temporal
scales cover both steady-state and time-dependent conditions and
can range from minutes and seconds in real-time systems to

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                          hourly, daily, weekly, or monthly for field systems, to years,
                          decades, and millennia for long-term risk simulations (e.g., for
                          radioactive wastes).

                              Another dimension of the ground water modeling field is the
                          difference in characteristics between models describing hydraulic
                          behavior of fluids in various subsurface environments and models
                          describing the transport and fate of chemicals in the subsurface.

                              Finally, there is a distinction between site-specific and generic
                          models. Site-specific modeling is particularly relevant to
                          hazardous waste sites falling under the purview of RCRA and
                          CERCLA.  Generic models are useful in situations where
                          environmental analysis must be applied to many sites where data
                          availability is limited or  other constraints make site-specific
                          modeling infeasible.

Relationship to
OSWER  Programs
                              Environmental  legislation and regulations, including RCRA
                          and CERCLA, address four common requirements for managing
                          ground water quality:

                          •  Establishment of  criteria for location, design, and operation of
                             waste disposal activities to prevent contamination of ground
                             water or movement of contaminants to points of withdrawal or
                             discharge.

                          •  Assessment of the probable impact of existing pollution on
                             ground water at points of withdrawal or discharge.

                          •  Development of remediation technologies which are effective
                             in protecting or restoring ground water quality without being
                             unnecessarily complex or costly, and without unduly restricting
                             other land use activities.

                          •  Regulation of the production, use, and/or disposal of specific
                             chemicals possessing  an unacceptably high potential for
                             contaminating ground water when released to the subsurface
                             (G21).

                              Ground water models may address one or more of these
                          requirements in a variety of different applications.  For example,
                          the predictive capabilities of ground water quality models are used
                          to evaluate design alternatives for waste disposal facilities, locate
                          areas of potential environmental  risk, identify pollution sources,
                          and assess possible remedial actions.
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Key Ground Water
Research
Organizations and
Modeling Centers
Robert S. Kerr
Environmental
Research Laboratory
Holcomb Research
Institute
    There are several key EPA and affiliated organizations
involved in ground water modeling.  Because ground water
modeling is a broad, multidisciplinary field, this section focuses on
OSWER-related ground water modeling activities.  For example,
the U.S. Geological Survey has been involved in ground water
modeling since the late 1960s and has developed a comprehensive
suite of generic simulation and parameter estimation models.

    The Robert S. Kerr Environmental Research Laboratory
(RSKERL) in Ada, Oklahoma, is the lead ORD laboratory for
ground water research. RSKERL focuses on the transport and fate
of contaminants in the subsurface, development of methodologies
for protection and restoration of ground water quality, and
evaluation of the applicability and limitations of using natural soil
and subsurface processes for the treatment of hazardous wastes.

    RSKERL carries out  research through in-house projects and
cooperative and inter-agency agreements with universities,
national laboratories, and other research centers.  Many of these
projects involve some type of research and development activity
related to the creation or refinement of ground water models.

    The Holcomb Research  Institute (HRI) at Butler University in
Indianapolis, Indiana, established The International Ground Water
Modeling Center (IGWMC) in 1978 to advance and support the
application of ground water models by regulatory and oversight
agencies involved in developing  effective ground water
management programs. IGWMC is supported partly by HRI and
partly by EPA (through RSKERL in Ada). The Center operates a
clearinghouse for ground water modeling software, organizes and
conducts short-courses and seminars, carries out a research
program supporting its technology transfer and educational
activities, and does verification and validation for some models.

    IGWMC also maintains  close ties with ground water modelers
at USGS and has established  an agreement to provide similar types
of support to the European Economic Community. In the future,
IGWMC will include European ground water models into its
existing model inventory and clearinghouse function.
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Athens Environmental
Research Laboratory
OSWER'sOfficeof
Program Management
and Technology
Office of Solid Waste
Findings
    The Athens Environmental Research Laboratory (A-ERL)
collaborates with RSKERL in several ground water research and
model development efforts. In particular, A-ERL supports PRZM
and MINTEQ, both of which are used in ground water analysis, the
former for root zone soil/water exposure and the latter for
geochemical analysis. Later this year, A-ERL will begin supporting
RUSTIC, an integrated soil/ground water model.

    The Office of Program Management and Technology (OPMT)
provides management and technical support for Headquarters and
Regional Offices. OPMT's primary involvement in ground water
modeling is through the deployment and support of the Ground
Water Workstation (GWWS) in each of the ten regions.  GWWS is
a microcomputer (PC-AT) equipped with a math co-processor,
plotter, and light pen. Four models were supplied with the initial
release of the GWWS, and OPMT is now evaluating requirements
for the next generation of GWWS.

    OPMT has also helped to establish a Ground Water Forum
through its Technology Support Project.  The purpose of the
Forum is to provide a channel for communication on ground
water issues, including modeling.  The Forum has one or more
representatives from each Region and two ORD representatives
(from RSKERL and the Environmental Monitoring and Systems
Laboratory in Las Vegas).

    The Office of  Solid Waste (OSW) has been involved in ground
water modeling to  varying degrees in the past.  Currently, the
Technical Assessment Branch in OSW's Characterization and
Assessment Division is developing a ground water model called
the EPA Composite Landfill Model (EPACLM). At one time, OSW
had a larger in-house modeling group, but now, OSW maintains
more of an oversight role, supporting the development of models
by ORD and supporting users of ground water models in the
Regional offices.
                            The findings presented below have been synthesized from
                        numerous interviews conducted at EPA Headquarters, RSKERL,
                        Regional Offices, and HRI (see Appendix B for names and dates)
                        and through the review of a variety of ground water modeling
                        reference materials (see Appendix C).
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                             Ground water modeling has matured rapidly since numerical
                         methods were first used in ground water hydrology in the mid-
Mode/ Developmen t      1950s. In the 1960s, the availability of computer technology made it
                         possible to simulate ground water systems efficiently through the
                         use of software instead of physical scale models or electric analogs
                         (G10). Today, IGWMC has identified approximately 800 ground
                         water models which are in various stages of development and
                         usage.

                             Models are being developed by a variety of government
                         agencies, such as EPA and USGS, universities, and industrial
                         organizations, such as energy and mining companies. One
                         example of the work being done within EPA is at RSKERL, where
                         recent model research and development efforts include:

                         •  The  Regulatory and Investigative Treatment Zone Model
                            (RITZ).

                         •  OASIS

                         •  Contaminated Profile (CONTPRO).

                             Some model development efforts begin in an academic setting
                         as research projects. These tend to be more focused on modeling
                         new processes or improving predictive power in ground water
                         systems. Other efforts are initiated as the direct result of requests
                         from program offices such as Regional Waste Management
                         Divisions. Such was the case for CONTPRO, which was originated
                         after a request from EPA Region nt. (CONTPRO is currently being
                         developed at Oklahoma State University and is written in
                         Microsoft C). Typically, before RSKERL staff get involved in a
                         modeling effort, requests for assistance are directed from the
                         Regional offices to their Ground Water Forum Representative and
                         then to  the lab managers.

                             New modeling initiatives typically follow in the wake of
                         advances in primary research.  RSKERL is actively participating
                         and/or sponsoring ground water research in several  new areas,
                         such as flows of multi-phase fluids, fractured/structured rock
                         problems, biotransformations in ground water, and the mobility of
                         large molecules through the soil.

                             The increasing availability of microcomputers has had a
                         significant impact on model development.  In ground water
                         modeling, there is a general consensus that microcomputers and
                         workstations are the preferred platforms for development and
                         delivery.  Most ground water researchers are now targeting micros
                         as their delivery environment  and there is a greater proportion of
                         modelers who develop their own code. At RSKERL, for example,
                         there are numerous IBM compatible microcomputers and one
                         Apple Macintosh, and the ratio of staff to micros is close to 1:1.
                         RSKERL plans to continue to upgrade its computing  capacity in the
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                         future, and is now considering the purchase of several more
                         Macintoshes. Currently, there are few models requiring significant
                         increases in computing capacity that would necessitate the use of
                         supercomputer technology, although in the future this technology
                         might be extremely valuable in  answering long-term risk questions
                         for large areas and populations (e.g., predicting the long-term
                         effects of ground water contamination in a large aquifer on human
                         health in a metropolitan area).

                              Modelers report that data entry and user interface issues are
                         still a major obstacle affecting usability. They note the importance
                         of good software engineering practices in producing quality front-
                         end capabilities such as data entry screens in contributing to the
                         acceptance of a model by users. RTTZ is a PC-based model that
                         provides a good example of a simple and effective user interface
                         consisting of three data entry screens. OASIS is an example of an
                         effort designed to incorporate an icon-oriented user interface as a
                         front-end for ground water models:  it is based on the Macintosh
                         and uses HyperCard software to provide users with simple point-
                         and-click commands. OASIS then passes the user inputs to a
                         model, which in this case, is a FORTRAN model called
                         BIOPLUME.

                              The ground water modeling community has devoted a great
                         deal of attention to analyzing development, application,
                         verification, and validation issues.  IGWMC has  taken the lead in
                         many of these efforts to describe and recommend standard model
                         development and application  procedures (see documents in the
                         Bibliography under "Ground Water", Appendix C).  These studies
                         and interviews with ground water modelers can be summarized as
                         follows:

                         • There are generally understood "rules of the road" and
                            principles of "good  science,"  but there are no universally
                            accepted standards for model development, application, and
                            use.

                         • Managers and modelers do not always agree on definitions for
                            key terms such as "verification"  and "validation."  For EPA
                            purposes, the way around  this controversy is  to focus on
                            answering two questions:  (1) For verification, "Are the
                            numerical equations of the model properly captured in the
                            computer code?" and (2) For validation, the key question is
                            whether the model is being applied appropriately, given the
                            model's assumptions and the characteristics of the specific
                            modeling case.

                         • There is no foreseeable way to entirely eliminate the possibility
                            that models will be misused, but there are ways to reduce the
                            likelihood of this happening. Some modeling experts feel that
                            the best way to do this is to focus on improving the knowledge
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Model Ueveiopmen t          Ground water modeling has matured rapidly since numerical
                         methods were first used in ground water hydrology in the mid-
                         1950s. In the 1960s, the availability of computer technology made it
                         possible to simulate ground water systems efficiently through the
                         use of software instead of physical scale models or electric analogs
                         (G10). Today, IGWMC has identified approximately 800 ground
                         water models which are in various stages of development and
                         usage.

                             Models are being developed by a variety of government
                         agencies, such as EPA and USGS, universities, and  industrial
                         organizations, such as energy and mining companies.  One
                         example of the work being done within EPA is at RSKERL, where
                         recent model research and development efforts include:

                         •  The Regulatory and Investigative Treatment Zone Model
                            (RITZ).

                         •  OASIS

                         •  Contaminated Profile (CONTPRO).

                             Some model development efforts begin in an academic setting
                         as research projects. These tend to be more focused on modeling
                         new processes or improving predictive power in ground water
                         systems. Other efforts are initiated as the direct result of requests
                         from program offices such as Regional Waste Management
                         Divisions. Such was the case for CONTPRO, which was originated
                         after a request from EPA Region ffl. (CONTPRO is currently being
                         developed at Oklahoma State University and is written in
                         Microsoft C). Typically, before RSKERL staff get involved in a
                         modeling effort, requests for assistance are directed from the
                         Regional offices to their Ground Water Forum Representative and
                         then to the lab managers.

                             New modeling initiatives typically follow in the wake of
                         advances in primary research. RSKERL is actively participating
                         and/or sponsoring ground water research in several new areas,
                         such as flows of multi-phase fluids, fractured/structured rock
                         problems, biotransformations in ground water, and the mobility of
                         large molecules through the soil.

                             The increasing availability of microcomputers  has had a
                         significant impact on model  development.  In ground water
                         modeling, there is a general  consensus that microcomputers and
                         workstations are the preferred platforms for development and
                         delivery.  Most ground water researchers are now targeting micros
                         as their delivery environment and there is a greater proportion of
                         modelers who develop their  own code. At RSKERL, for example,
                         there are numerous IBM compatible microcomputers and one
                         Apple Macintosh, and the ratio of staff to micros is dose to  1:1.
                         RSKERL plans to continue to upgrade its computing capacity in the
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                         future, and is now considering the purchase of several more
                         Macintoshes. Currently, there are few models requiring significant
                         increases in computing capacity that would necessitate the use of
                         supercomputer technology, although in the future this technology
                         might be extremely valuable in  answering long-term risk questions
                         for large areas and populations (e.g., predicting the long-term
                         effects of ground water contamination in a large aquifer on human
                         health in a metropolitan area).

                              Modelers report that data entry and user interface issues are
                         still a major obstacle affecting usability. They note the importance
                         of good software engineering practices in producing quality front-
                         end capabilities such as data entry screens in contributing to the
                         acceptance of a model by users. RTTZ is a PC-based model that
                         provides a good example of a simple and effective user interface
                         consisting of three data entry screens. OASIS is an example of an
                         effort designed to incorporate an icon-oriented user interface as a
                         front-end for ground water models: it is based on the Macintosh
                         and uses HyperCard software to provide users with simple point-
                         and-click commands. OASIS then passes the user inputs to a
                         model, which in this case, is a FORTRAN model called
                         BIOPLUME.

                              The ground water modeling community has devoted a great
                         deal of attention to analyzing development, application,
                         verification, and validation issues.  IGWMC has taken the lead in
                         many of these efforts to describe and recommend standard model
                         development and application procedures (sese documents in the
                         Bibliography under "Ground Water", Appendix C).  These studies
                         and interviews with ground water modelers can be summarized as
                         follows:

                         • There are generally understood "rules of the road" and
                            principles of "good  science,"  but there are no universally
                            accepted standards for  model development, application, and
                            use.

                         • Managers and modelers do not always agree on definitions for
                            key terms such as "verification" and "validation."  For  EPA
                            purposes, the way around  this controversy is to focus on
                            answering two questions:  (1) For verification, "Are the
                            numerical equations of the model properly captured in the
                            computer  code?" and (2) For validation, the key question is
                            whether the model is being applied appropriately, given the
                            model's assumptions and the characteristics of the specific
                            modeling  case.

                         • There is no foreseeable way to entirely eliminate the possibility
                            that models will be misused, but there are ways to reduce the
                            likelihood of this happening.  Some modeling experts feel that
                            the best way to do this  is to focus on improving the knowledge
3-7

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                            and experience of the model users, not to worry about flawless
                            software.

                         •  Model validation is a continual process. Modelers are typically
                            involved in some type of validation effort for their model, but
                            as the model becomes more widely distributed and applied in
                            different scenarios, it becomes difficult to keep track of its
                            successes and failures.  Model clearinghouses and user support
                            groups can make a major contribution in this area.

                         •  Peer review processes for models are mostly determined by the
                            organization sponsoring the development.  For example, peer
                            review  procedures within EPA are often different from those
                            followed by universities.

                         •  Some modelers suggest that high level attempts to establish a
                            standard set of approved models may have the undesirable
                            effect of limiting innovation.

                         •  Model selection is a complex issue that involves clearly
                            answering such difficult questions as: "What is the specific
                            question that must  be answered?" and "What level of
                            uncertainty is acceptable?".

                         •  Often there is a trade-off between selecting a model that best fits
                            the ground water conditions and one that best fits the regulatory
                            scenario.

Usage and Support           The organizations identified earlier all directly or indirectly
                         support ground water  modeling in the field:  RSKERL, IGWMC,
                         OPMT, and the Ground Water Forum.  RSKERL and IGWMC are
                         the main sources providing guidance on model selection,
                         application and validation. They also conduct training through
                         "short courses" and Regional seminars. OPMT supports the
                         Ground Water Workstation program which has deployed a
                         microcomputer equipped with a basic modeling tool kit in each  of
                         the ten Regions. OPMT has also sponsored training on the
                         workstation and provided documentation. The Ground Water
                         Forum provides a central forum for the discussion of ground water
                         issues, including modeling.

                             IGWMC is the primary user support organization for ground
                         water modeling, maintaining a database of approximately 800
                         models, including documentation for approximately 300 models.
                         IGWMC manages and distributes codes for 50-60 models. IGWMC
                         has also provided testing and validation services to model users.
                         In the future, IGWMC would like to expand its offerings to include
                         an electronic bulletin board and maintain a more complete set of
                         QA information for each model (e.g., track records of model
                         performance under various scenarios).  Some models may have
                         many different versions and changes are often managed on an ad
_ _                      hoc basis.
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                              IGWMC also provides testing and validation services to
                         model users. At the high end, IGWMC works directly with the
                         model users and/or developers to discuss technical issues and
                         address requirements for refinement and validation.  At the low
                         end, IGWMC may provide users with some limited
                         documentation and advise them to "use at your own discretion."

                              For IGWMC, it is becoming increasingly challenging to
                         effectively support non-expert users as ground water models
                         become more complex and incorporate new issues (e.g.,
                         microbiology). Therefore, developing and maintaining forums for
                         user and modeler communication, such as user groups and
                         bulletin boards, will be of greater importance in the future.

                              Regional office staff devote a significant portion of their efforts
                         to reviews of contractors' proposals, work plans, and remediation
                         efforts. Many contractors submit models and their results to the
                         EPA for review.  The Regional office must determine if the proper
                         model has been chosen for the site, and whether or not the model
                         has been applied in a valid manner. Therefore, the EPA reviewer
                         needs  to understand the available models and their valid
                         application,  and be able to identify cases where an in-depth review
                         of a contractor's work is warranted. In some contested cases, EPA
                         reviewers may need to compare their own modeling results with
                         modeling results of regulated facilities, Principal Responsible
                         Parties (PRPs), and their consultants.  Alternative model
                         assumptions, parameters, and boundary conditions must be
                         considered carefully in order to  validate the model application.

                              In the Regional offices, the use of ground water models is
                         limited by constraints on time, human resources, and computer
                         resources. The following user support issues were identified by the
                         Regions:

                         •   To be used effectively by staff in  the Regional Waste
                              Management Divisions, models must be easy to learn and
                              significantly improve either the quality of decision-making or
                              the efficiency with which decisions can be made.

                         •   The expertise and knowledge to use models cannot be
                              acquired quickly in most cases. In most cases, the users are not
                              modeling experts.  They may have training in hydrology,
                              geology, toxicology, management, or environmental science,
                              but typically, they will not have in-depth modeling
                              experience.  Models are just one of several tools they rely on to
                              perform their jobs.

                         •   Limited availability of computer resources and lack of
                              computer skills increase the costs of using models both in
                              terms of time and money. Some models require users to
                              procure additional software packages or hardware (e.g., math
_ _                           co-processors), and many models assume the user has a
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                             certain amount of computer expertise in order to input data
                             and run the model. These requirements and assumptions
                             create entry barriers for unprepared and uninitiated model
                             users.

                             In addition to these user support issues, Regional model users
                        identified a variety of entry barriers for modeling. These include:

                        •   Data input is too time consuming.

                        •   Data is not always available.

                        •   The model does not make use of all the information available.

                        •   The model makes too many assumptions.

                        •   The model is too complex to understand.

                        •   Debugging input files takes too much time.

                             Regional model users are satisfied with some of the types of
                        user support available to them. Some have contacts in ORD
                        laboratories or academia, whom they call on for assistance. Some
                        user groups and training classes are viewed as helpful, but only if
                        the modelers can return from the classes and immediately apply
                        what they have learned.

                             Some formal training in ground water modeling has been
                        attempted on a national scale.  During the summer of 1988, for
                        example, RSKERL completed a series of three-day seminars in each
                        of the ten EPA Regions. These seminars provided attendees with
                        descriptions for a selected subset of models, explained model
                        assumptions and variability, and included some hands-on training.
                        Source code was distributed for some of the models. The  seminars
                        were attended by a combination of Superfund and RCRA staff from
                        the Regions, as well as contractor staff The coordinator of these
                        seminars provided the following observations:

                        •   Model usage varies significantly from Region to Region, and
                             depends on the level of expertise in the Regional or EPA-HQ
                             program offices, the availability of an appropriate model with
                             sufficient documentation, and  the complexity of the problem
                             to be analyzed.

                        •   Some Regions have in-house hydrologists and geologists who
                             are experienced modelers. Other Regions have practically no
                             staff with any in-depth  modeling experience.

                        •   On average, Regional staff involved in RCRA and CERCLA
                             programs face heavy demands on their time (e.g., some RPMs
                             manage more than twenty sites simultaneously) and have no
                             time to devote to acquiring additional modeling expertise.
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                          •   Often, because of their busy schedules, those who could benefit
                              most from additional training are the least likely to attend
                              training when it is offered.  Regional staff often skip modeling
                              courses because of more pressing day-to-day activities.

                          •   Basic computer literacy is sometimes a significant obstacle to
                              making the training sessions worthwhile.

                              RSKERL and IGWMC agree that more technical expertise is
                          needed in all Regions. Regional staff do not need to be modelers,
                          but they need to be knowledgeable generalists who can make
                          decisions after reviewing information from a variety of sources
                          (e.g., ORD, PRPs, contractors). The Regions also need computer
                          support staff who can eliminate some of the confusion created by
                          difficult user interfaces and complex sets of operating instructions
                          for some models.  RSKERL plans to continue sponsoring seminars
                          and training on ground water models and is now assessing
                          priorities and formats for future courses.
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Section 3.2.
Exposure Assessment Modeling
Size and Scope
Relationship  to
OSWER Programs
                             Exposure assessment modeling is a growing category of
                         models useful for supporting OSWER program activities. This
                         study has so far identified more than a dozen readily available
                         models, not including the many under development by various
                         universities and research organizations.  The number and variety
                         of available exposure assessment models has increased steadily in
                         recent years because they have proven to be valuable components
                         of risk-based decision processes. This trend is likely to continue in
                         the 1990s.

                             The majority of exposure assessment models identified so far
                         focuses on ecological exposure where water is the primary pathway.
                         They represent a wide range of analysis techniques, including
                         simple analytical procedures suitable for screening analysis,
                         computerized steady-state models, state-of-the-art continuous
                         simulation  models, and interactive graphics.  Exposure assessment
                         models relating to human exposure also exist for air and other
                         pathways.  Exposure assessment modeling is usually directly
                         related to transport and fate modeling in various media, and
                         therefore, coordination and cross-fertilization among the various
                         research organizations with in-depth expertise in these media is
                         necessary.
                             Exposure assessment models have been used under various
                        legislative mandates, including RCRA, and CERCLA. Exposure
                        assessment models can be used by Regional RCRA and Superfund
                        staff and their consultants to make decisions on issues such as
                        human and ecological exposures resulting from contamination at
                        Superfund sites and emissions resulting from hazardous waste
                        incinerators. Examples of the types of capabilities available to
                        OSWER through the exposure assessment models identified so far
                        include:

                        •   multimedia modeling of organic chemical and heavy metal
                             pollutant fate

                        •   regional and local air contaminant modeling

                        •   source and site characterization, monitoring, and
                             measurement
3-12
                            marine and estuarine pollutant fate modeling

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Key Exposure
Assessment
Research
Organizations and
Modeling Centers
                             pollutant dose-response modeling

                             ecological impact and ecological risk assessment. (El)
Center for Exposure
Assessment Modeling
    This section briefly describes the major exposure assessment
modeling centers and research organizations identified in this
study.  Exposure assessment can be applied to most environmental
media, and organizations other than those listed here may also be
engaged in exposure assessment modeling.  An example of an
organization which has not been categorized here under exposure
assessment is the Atmospheric Research and Exposure Assessment
Laboratory (AREAL) which was created recently to increase the
emphasis on developing exposure assessment models for air.
AREAL is categorized under Air Dispersion Modeling in this
report because it is not yet heavily involved in exposure modeling
and most of its prior modeling activities are related to air
dispersion analyses.

    The Center for Exposure Assessment Modeling (CEAM) was
established in July, 1987 to meet  the scientific and technical
exposure assessment needs of EPA program offices at both the
Headquarters and Regional levels, as well as state environmental
agencies. CEAM is the OSWER-designated Technical Support
Center for Ecological Risk Assessment.  The Center is also the focal
point for a variety of general Agency support activities related to
the scientifically defensible application of state-of-the-art exposure
assessment technology for environmental risk-based decisions.
CEAM provides exposure assessment technology, training and
consultation for analysts and decision-makers operating under
various legislative mandates, including RCRA, and CERCLA.

    CEAM is a matrix organization within ORD which draws its
exposure assessment expertise from its parent laboratory, the
Environmental Research Laboratory at Athens, Georgia (ERL-
Athens), plus affiliated laboratories including ERL-Duluth; the
Environmental Monitoring Systems Laboratory, Las  Vegas, NV
(EMSL-Las Vegas); ERL-Narragansett; the Atmospheric Research
and Exposure Assessment Laboratory (AREAL),  Research Triangle
Park (formerly, the Atmospheric Sciences Research Laboratory and
the Environmental Monitoring Systems Laboratory at RTP); ERL-
Gulf Breeze;; and EMSL-Cincinnati.

    CEAM currently supports twelve exposure assessment
models, six of which are related to remedial actions.  Other models
are currently being integrated into the CEAM program.
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Office of Toxic
Substances
Atmospheric Research
and Exposure
Assessment Laboratory
Findings
Model Developmen t
    The Office of Toxic Substances (OTS) has supported the
development of GEMS, the Graphical Exposure Modeling System.
GEMS has been used by OSW for hazardous waste incinerator
regulations, unsaturated zone modeling, and estimation of
physical-chemical properties for waste constituents.

    AREAL focuses on exposure assessments for air pathways and
is currently working on basic assumptions about units of exposure.
One existing model is called the Simulation of Human Activity
Patterns (SHAPE). SHAPE predicts carbon monoxide exposure for
humans under various activity scenarios. Field tests and data
collection for this model are now being conducted in Denver,
Colorado, and Washington, D.C.
    The findings presented below have been synthesized from
numerous interviews conducted at EPA Headquarters and several
ORD laboratories (see Appendix B for names and dates) and
through the review of a variety of exposure assessment modeling
reference materials (see Appendix C).

    In the exposure assessment category, recent model
development efforts have concentrated on the integration and
combination of existing models, rather than on the development
of entirely new models. New models are also being developed, but
a greater emphasis has been placed on conjunctive use of various
types of models addressing different exposure pathways and/or
environmental processes. For example, one research project under
way at ERL-Athens involves piecing together several models,
essentially using the outputs of one model as the inputs for the
next. This is a complex task which attempts to make estimates
based on estimates. One thrust of this project is to isolate and
identify the basic levels of complexity which can be handled within
acceptable bounds of uncertainty. Another thrust of the
investigation is to develop consistent interfaces between models.

    Other model development projects focusing on ecological risk
assessment, land disposal of hazardous wastes, and exposure
assessment models for pesticides include:

•  Multimedia Exposure Assessment Model for Hazardous
    Wastes

•  Pesticide Ground Water Exposure Assessment Model

•  Terrestrial Environmental Exposure Assessment Model.

    Another ERL-Athens research effort is focused on validating
certain model assumptions for  Eco-Risk models such as FGETS.
For GEMS, recent development work has produced a PC-based user
interface which can be readily distributed and used.
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                              CEAM has established several basic development standards
                         for models distributed by the Center. These include hardware,
                         software, portability, and documentation guidelines and criteria
                         which must be met before the Center will accept a model for
                         support and distribution. The CEAM software standard is ANSI
                         FORTRAN 77; all models are compiled successfully using four
                         different FORTRAN compilers before they are approved for
                         distribution. This procedure assures portability between a variety
                         of hardware platforms including mainframes (IBM, PRIME, Cyber,
                         HP), minicomputers (VAX), and microcomputers (IBM PC/AT).
                         Comprehensive scientific and user documentation is  also required
                         for acceptance.

                              CEAM also plays a significant role in the verification,
                         validation, and quality control of exposure assessment models.  For
                         verification, CEAM undertakes a detailed code-level review of
                         models. This assures internal consistency and valid representation
                         of scientific equations.  CEAM has worked with the EPA Office of
                         Water to develop waste load allocation guidance documents,
                         which address some model application and validation issues, but
                         do not provide specific guidelines. CEAM participates in validating
                         exposure assessment models primarily through two activities: peer
                         review journals and user group meetings.  The issue  of model
                         validation is itself a research topic at CEAM. For example, the
                         exposure model PRZM underwent five years of validation efforts
                         (at considerable cost) to determine the valid boundaries for the
                         application of the model.

Model Usage and             Although CEAM  functions influence the development of
Support                 exposure assessment models, the primary purpose of  the Center is
                         to provide expert support services for the users of CEAM models.
                         CEAM provides services in three primary functional  areas:

                         •   Model Distribution and Maintenance.  This functions
                              ensures that those conducting exposure assessments have
                              access to the necessary models, databases, and analytical
                              techniques.  This  involves model acquisition, preparation,
                              maintenance, distribution, support, and quality assurance.
                              CEAM distributes and supports a set of twelve exposure
                              assessment models; three to four models will be  added to this
                              set during the next year. Distribution includes model codes as
                              well as documentation and reference  materials.  CEAM
                              distributed over 1,500 copies of models last year and over 1,900
                              copies in FY '87. One tool used to support the distribution and
                              support function is an electronic bulletin board.  The bulletin
                              board enables callers to download model codes and some types
                              of documents, as well as leave messages and ask questions
                              about particular models.  About one-third of the models
                              distributed last year were sent out electronically  via the
                              bulletin board.  The remaining two-thirds of the models were
                              distributed in user-requested formats on floppy disks or tapes.
3.15                         Four  full-time CEAM staff members,  including contractors,

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                             are dedicated to the technical provision function.  This
                             function also covers the maintenance of a user database,
                             model recalls, issuance of updated codes, and software reviews
                             to ensure uniform coding styles and constructs. CEAM
                             conducts line-by-line code reviews for some of the models it
                             distributes.  The Center does not function as a clearinghouse
                             for all exposure assessment models.  As research and
                             development lead to new or improved modeling capabilities,
                             CEAM updates presently supported models and adopts new
                             models.

                         •   Technical Support.  CEAM offers extensive technical support
                             for all of the models distributed by the Center. Support
                             includes training and seminars, phone support, input data
                             analysis and error correction through the bulletin board, site-
                             specific guidance, and access to subject matter experts. CEAM
                             emphasizes support because some type of technical assistance
                             is required for most model applications. Phone support is
                             provided mainly through contractor staff. CEAM staff
                             provides direct consulting support for those models they
                             thoroughly understand; they provide contact with outside
                             experts for other models.  Training consists of three- to five-
                             day short courses in the use and application of certain CEAM
                             models. CEAM presented two short courses in FY88: "Models
                             of Exposure and Bioaccumulation of Organic Toxicants in
                             Surface Waters," held in Washington, DC, and Boulder,
                             Colorado, and the "Metals Equilibrium Speciation Model
                             (MINTEQA2)," held in Boulder, Colorado.  Three  short
                             courses are planned for FY89.  CEAM provides site-specific
                             guidance in cases where the exposure assessment modeling
                             expertise of the CEAM staff is needed. An example of this is
                             the support requested by OSW at a wood preservative waste
                             site in Georgia.  CEAM staff members used PRZM and FGETS,
                             two CEAM models, to assist with the analysis of the waste site.
                             CEAM staff may assist with model selection and application
                             when requested.

                         •   Demonstration. The purpose of technical demonstration is to
                             specifically demonstrate the models and techniques supported
                             by the Center.  Through these demonstrations, CEAM can
                             promote new analysis techniques and address specific
                             management issues.  One technical demonstration currently
                             underway is an eco-risk analysis in the Clark Fork River,
                             Montana.  The analysis team was drawn from the staffs of ERL
                             Athens and ERL Duluth.

                             CEAM currently supports only twelve models because of the
                         interest in providing solid technical  support for each of the
                         available models. Therefore, models are added to CEAM inventory
                         at a gradual rate which ensures they can be effectively supported
                         with existing resources.
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Section  3.3
                         Air  Dispersion Modeling
Size and Scope
Relationship to
OSWER Programs
3-17
                             Air dispersion models have been managed and used over a
                         longer period of time than most other model types. The core set of
                         EPA air dispersion models, called the Users Network for Applied
                         Modeling of Air Pollution (UNAMAP), has existed since 1973.
                         UNAMAP consists of 23 air dispersion models of various types
                         which have been funded and/or developed by EPA.

                             Historically, air dispersion models have been used primarily
                         to support development of State Implementation Plans (SIPs)
                         mandated by the Clean Air Act, and to conduct new source
                         reviews. Because of the difficulty and high cost of collecting air
                         monitoring data with comprehensive spatial and temporal
                         coverage, models have been widely used in many air quality
                        ^assessments, supported by actual air data where possible.  The use
                        . of models is authorized by Federal regulations  (40 CFR, Parts 51 and
                         52) issued under the authority of the Clean Air Act. These
                         regulations specify the EPA Guideline on Air Quality Models as the
                         official guidance document for determining which UNAMAP
                         models are best suited to a particular regulatory requirement.
                         Criteria influencing the selection of the preferred models include:
                         short-term (1-24 hours) vs. long-term (monthly, seasonal, or
                         annual); type of source (single, multiple, complicated, buoyant);
                         type of terrain (simple or complex); and land use (urban, rural).
                             Many of the widely used air dispersion models pre-date RCRA
                         and CERCLA and are oriented toward air regulatory programs
                         managed by the Office of Air Quality Planning and Standards
                         (OAQPS).  In recent years, however, there has been increasing
                         interest in using air models to support OSW and OERR programs.
                         For OSW, one of the main areas of interest is in modeling air
                         dispersion patterns in order to predict the transport of pollutants
                         emitted from hazardous waste incinerators. For OERR's purposes,
                         air dispersion models can be valuable in assessing volatilization of
                         pollutants from Superfund sites.  Exhibit 3.3-1 shows some of the
                         air contaminant pathways from a landfill.  Models can sometimes
                         be the only feasible way to determine safe  courses of action, such as
                         evacuation in emergency  cases where there are sudden releases of
                         hazardous materials into  the air.  Air modelers in ORD have
                         identified some of  the air models that are most directly applicable
                         to OSWER programs. These include a model that can be used at
                         landfill sites containing hazardous wastes  and a model that
                         simulates instantaneous releases of hazardous materials and could
                         be used in an emergency response situation.

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                                                DIRECT AIR EMSSKMS OF
                                             VOLAT1LES * PARTCULATE MATTER
                                QA8VENTMQ
                                FROM VENTS
                                  VOLATILIZATION
                                OF UNSOLVED SPECIES
                                 M GROUND WATER
                                                                         LATERAL HKIRATION
                                                                          OFVOLATILES
                                                                         FROM SOLID WASTE
                                                                        LATERAL MIGRATION
                                                                         OFVOLATILES
                                                                        FROM CONTAMMATEO
                                                                        SCNLSALEACHATE
                                               Exhibit 33-1 (reprinted from A7)
Key Air Dispersion
Research
Organizations and
Modeling Centers
Atmospheric Research
and Exposure
Assessment Laboratory
3-18
     Three major air dispersion modeling centers and research
organizations have been identified through the project team's
interviews at EPA Headquarters, ORD laboratories, and selected
EPA Regional Offices.

     The Atmospheric Research and Exposure Assessment
Laboratory (AREAL), in Research Triangle Park, North Carolina,
formerly the Atmospheric Science Research Laboratory (ASRL),
and  the Environmental Monitoring Systems Laboratory (EMSL)
manage the UNAMAP set of models. Activities supporting
UNAMAP include software maintenance and issuance of new
model codes. AREAL is currently operating an electronic bulletin
board. The bulletin board is used to distribute copies of models and
a limited amount of documentation,  and it provides a
communication channel for UNAMAP users.  AREAL is now
assessing future plans for continued  operation of the bulletin
board. One option under consideration is transferring
responsibility for the bulletin board to OAQPS (see below).

     AREAL's research and model development activities include
application of existing models in new regulatory settings,
development of a climatological Point, Area, and Line Source
model (PAL), and research on indoor air pollution.

     AREAL also provides technical support for other offices and
agencies such as the Office of Toxic Substances (OTS) and the
Federal Emergency Management Agency (FEMA).

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Air and Energy               The Air and Energy Engineering Research Laboratory (AEERL)
Engineering Research    conducts research on preventing Hazardous Air Pollutant /
Laboratory               Volatile Organic Compound (HAP/VOC) emissions and ensuring
                         effective application of control devices. This research supports the
                         development of New Source Performance Standards (NSPS) and
                         State Implementation Plans. AEERL also provides direct
                         engineering technical support to EPA Regional Offices and state
                         and local agencies.

                             One of AEERL's ongoing research projects with direct
                         relevance to OSW is the investigation  of hazardous waste puffs
                         from rotary kiln incinerators.  This project involves the use of a
                         small scale rotary kiln to measure the behavior of various
                         materials under different combustion scenarios.  Later phases of
                         this project are likely to include some type of model development
                         activity.

Office of Air Quality           The Office of Air Quality Planning and Standards (OAQPS) in
Planning and Standards  Research Triangle Park, North Carolina, is the program office
                         responsible for developing the Guideline on Air Quality Models.
                         During the 1970s and 1980s, OAQPS has worked directly with
                         AREAL and AEERL (and formerly, with ASRL) on the
                         development, review, and application of many of the UNAMAP
                         models.  OAQPS is now beginning work on updating the Guideline
                         and has established a work group, with OSWER membership, to
                         produce the revisions.  OAQPS is also involved in the
                         development of several air emissions  models (in collaboration
                         with the Risk Reduction and Engineering Laboratory  in
                         Cincinnati).

                             OAQPS has relied in the past on AREAL and the National
                         Technical Information Service (NTIS)  to distribute the UNAMAP
                         models.  Current initiatives include the establishment of a new
                         electronic bulletin board to replace AREAL's existing  bulletin
                         board. AREAL will continue to be involved  in model
                         development, application and validation and will continue to
                         provide technical support for UNAMAP users. OAQPS will
                         procure new hardware and establish a more formal user support
                         group  to operate the bulletin board.

                             OAQPS has recently established a joint effort with OERR and
                         the EPA Regions called the Air/Superfund Coordination Program.
                         The purpose of this program is provide technical support in areas
                         such as using air models to predict volatilization at Superfund
                         sites.

Findings
                             The findings presented below have been synthesized from
                         numerous interviews conducted at EPA Headquarters and
3 19                     Regional offices, AREAL, AEERL, and OAQPS (see Appendix B for

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                         names and dates) and through the review of a variety of air
                         dispersion modeling guideline documents and reference materials
                         (see Appendix C).
Model Development          The major research initiatives likely to add to the inventory of
                         air models in the future are:

                         •   indoor air pollution

                         •   exposure assessments for air pathways

                         •   source apportionment for air toxics

                         •   studies of atmospheric transformations for ozone

                         •   regional and national acid rain studies.

                             As for some of the other modeling categories, the trend in air
                         modeling is increased emphasis on microcomputers and
                         workstations for model development and delivery.  Again, user
                         interfaces are a key issue. Because of the need for large, complex
                         regional air models to address issues such as acid rain and global
                         warming, air has a more immediate need for supercomputer
                         technology than some other areas.

                             One of the unique aspects of the air modeling environment is
                         the existence of OAQPS's Guideline on Air Quality Models which
                         specifies preferred models for certain types of applications. The
                         Guideline has the force of regulation since it is incorporated by
                         reference in the Federal Register sections addressing Clean Air Act
                         requirements. Two major factors led to the development of the
                         Guideline: (1) the requirements set forth by the Clean Air Act  that
                         specified the use of models for developing air quality  management
                         plans; (2) the characteristics of the air medium make effective
                         monitoring very difficult. OAQPS will be revising the Guideline
                         in the future and has established a work group to produce the
                         update.  The work group will have three representatives from
                         outside of  the air program, including two OSWER representatives.
3-20

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                             The core group of models contained in UNAMAP changes
                         periodically; the current version of UNAMAP is the sixth since its
Model Usage and        inception in the early 1970s. Presently, the UNAMAP models are a
Support                  fairly stable set. UNAMAP is the main support mechanism for
                         users of air dispersion models. There is a steady demand for the
                         models and AREAL estimates that about half of all requests are for
                         regulatory purposes (e.g., Prevention of Significant Deterioration
                         (PSD) analysis). The National Technical Information Service
                         (NTIS) distributes the complete series of UNAMAP models on
                         magnetic tape at a cost of $1,285. The modeling codes available
                         through NTIS are written primarily in ANSI FORTRAN 77. Some
                         of the UNAMAP models are available in PC format, but this type of
                         customization is usually left to the users or to private companies
                         wishing to re-market the UNAMAP models.  OAQPS has created
                         compatible mainframe and PC versions for some models (e.g., ISC).

                             A second option for obtaining the models is to use  the AREAL
                         electronic bulletin board.  The bulletin board provides mostly
                         source code, although AREAL intends to make more text files (e.g.
                         documentation) available in the future. AREAL is assessing
                         whether to continue its current use of the bulletin board, expand it,
                         or transfer this responsibility to OAQPS. OAQPS has begun
                         preparations for housing the bulletin board and plans to use a SUN
                         workstation with four external ports as the host. OAQPS is also
                         undertaking an initiative to improve the overall quality of
                         documentation for UNAMAP models.

                             AREAL issues periodic changes to UNAMAP through
                         Versions and within Versions,  through Changes.  The current
                         UNAMAP series is Version 6, Change 8. Mailing lists of all
                         requestors are maintained and changes are sent out automatically.

                             AREAL staff also provides consulting for users, although the
                         staff stresses they  are only providing information on the technical
                         aspects of the models, not passing judgement on regulatory issues.
                         During recent years, the user profile has changed to include a larger
                         proportion of non-experts.

                             One of the modeling support areas of relevance to OSWER is
                         the Air/Superfund Coordination Program. This is a joint effort
                         between OAQPS, OERR, and the Regions to evaluate and assist
                         with the use of air models at Superfund sites;.  The program is
                         funded with Superfund resources, including  contract money and
                         Regional FTEs. Each Region has a designated Air/Superfund
                         Coordinator  who facilitates the  air analysis portions of Superfund
                         site investigations and remedial actions.

                             At the Regional offices, air models are often needed to
                         estimate the impacts of remediation efforts on air, including air
                         stripping, incineration, and volatilization.  Six of the twenty-three
                         UNAMAP models have been identified as having applicability in
                         RCRA and Superfund remediation sites. Of these six models, one

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                         model, the Industrial Source Complex model (ISC), is the most
                         commonly used. Other UNAMAP models are not widely
                         applicable to Superfund and RCRA sites because of differences in
                         the focus of the models, such as the orientation toward tall stack
                         emissions versus wide area volatilization.

                             Region HI is one of the most active Regions in the
                         Air/Superfund Coordination Program, and has designated two
                         modelers from the Air Management Division to provide support
                         for Superfund analyses. These individuals spend approximately
                         twenty-five percent  of their time on Superfund related air analysis
                         activities. Of this time, a little more than half is used for applying
                         air models at specific Superfund sites.  Air models were used by
                         Region HI modelers at a total of twelve Superfund sites in 1988.
                         Modeling activities include both reviewing the modeling efforts of
                         contractors and hands-on modeling requested by the Remedial
                         Project Manager. The modeling tools and techniques required for
                         RCRA sites are similar to those of Superfund sites, but air models
                         were used at only one or two RCRA sites in 1988.

                             OAQPS's Guideline on Air Quality Models is not generally
                         applicable to modeling in OSWER programs because of different
                         regulatory requirements and different spatial scales. Currently,
                         Superfund air modelers depend on their own expertise and past
                         experiences with air models. OAQPS and the Regional offices are
                         developing a document titled Procedures for Conducting Air
                         Pathway Analyses for Superfund Activities, which addresses issues
                         of consistency and quality in Superfund air analyses. This four
                         volume document, currently in draft form, provides guidance on
                         modeling and monitoring procedures to be used at Superfund sites.
                         The document will also have relevance in RCRA air analyses.
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Section  3.4.
Modeling for Hazardous Waste Engineering
Size and Scope
Relationship to
OSWER Programs
Hazardous Waste
Engineering
Research
Organizations and
Modeling Centers
3-23
                            The project team has identified four engineering models that
                        are particularly relevant to Hazardous Waste Engineering /
                        Superfund programs. The models are useful in the evaluation of
                        earthen dike structures, hazardous waste incinerators, landfills,
                        and liners.  Although numerous other engineering models have
                        been developed and may be in use by Regional offices, contractors,
                        or industry, these four were of primary interest to the interviewees
                        from OSWER and ORD:

                        •  Geotechnical Analysis for Review of Dike Stability (CARDS) -
                            assists in the evaluation of existing and planned earth dike
                            structures at hazardous waste facilities;

                        •  Energy-Mass Balance Model (EMBM) - simulates the
                            performance of industrial incinerators for a variety of
                            combustion scenarios;

                        •  Hydrologic Evaluation of Landfill Performance (HELP n) -
                            models hydrologic effects at hazardous waste sites;

                        •  Soil Liner Model (SOILINER) - simulates the dynamics of
                            infiltration through a compacted soil liner.

                        More detailed information on these models is provided in the
                        Models Inventory.
    Engineering models are used to support decisions meeting
both RCRA and CERCLA requirements.  For example, these types
of models can be used to evaluate the design and configuration of
Treatment, Storage, and Disposal Facilities (TSDs), as required by
RCRA. Incinerators, soil liners, dikes, and other hazardous waste
control technologies have been addressed by various types of
engineering models.  CERCLA applications for engineering models
focus on containment approaches and remedial techniques such as
incinerators for contaminated soils, impermeable barriers, and
landfill caps.

    The Risk Reduction Engineering Laboratory (RREL) in
Cincinnati, Ohio, which houses the former Hazardous Waste
Engineering Research Laboratory (HWERL), is one of the key
organizations involved in engineering models. RREL is
responsible for the development and distribution of the four
models mentioned above.

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                             The Air and Energy Engineering Laboratory (AEERL) is also
                         involved in engineering research.  One of AEERL's current
                         research projects is evaluating rotary kiln incineration of
                         hazardous wastes. This effort will most likely result in the
                         development of one or more models simulating various aspects of
                         incineration.

                             Other laboratories involved in engineering models include
                         the Las Vegas Environmental Monitoring and Systems Laboratory
                         (EMSL), and the Environmental Research Laboratory, Athens,
                         Georgia (ERL Athens).

Findings
                             As compared to some other modeling categories, engineering
                         models are a small group in terms of numbers.  The models vary
                         in terms of complexity according to the particular treatment
                         technology they simulate. A few engineering models such as HELP
                         n are widely distributed and account for the vast majority of total
                         models distributed. FORTRAN is the primary language used for
                         developing engineering models.

                             Interviewees identified less than five ongoing ORD research
                         projects that may lead to model  development. Two examples are
                         AEERL's research on rotary kiln incinerators mentioned above and
                         an effort at RREL to develop a metals partitioning model mat
                         predicts how metals behave under a variety of incineration
                         scenarios.

                             There are no formal user support and model distribution
                         networks for engineering models. RREL typically provides copies
                         of models on blank diskettes supplied by the requestor. RREL is
                         considering establishing an arrangement with the Center for
                         Environmental Research Information (CERI)  to provide
                         documentation and support.  They have also considered providing
                         this type of service through the National Technical Information
                         Service (NTIS), but feel that CERI will be more economical and
                         more responsive, (see the description of CERI in Section 2.3).

                             RREL is also working with the Office of Solid Waste to
                         investigate the use of expert systems technology for supporting the
                         evaluation of "Method 90-90" data on flexible membrane liners.
3-24

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Section 3.5.
Surface Water Modeling
Size and Scope
                              Surface water modeling covers a variety of processes which
                          occur in the surface bodies of water.  Modelers group these water
                          bodies into three categories: rivers and streams, lakes and
                          reservoirs, and estuaries and bays. Within these categories, lakes
                          are sub-categorized into stratified or well mixed, and estuaries are
                          sub-categorized into stratified, well mixed, or partly mixed. Of the
                          three categories, estuaries and bays is the most complex because of
                          the numerous forces acting on the waters, including tides, thermal
                          mixing, and the Coriolis (spinning earth) effect.  Because the
                          transport of hazardous materials in surface water pathways is
                          dependent on both the water and the underlying sediments, many
                          surface water models simulate processes both in the water and in
                          the sediments which underlie and intermingle with the water.
                          Exhibit 3.5-1 diagrams the chemical and biological processes which
                          occur in surface waters.
                                        VOLATILIZATION
                            ATMOSPHERE
MATER
01
X SEDINEK
t DIRECT
PHOTOLYSIS


DISSOLVED
POLLUTANT
HYDROLYSIS-)
OXIDATION
FFUSION
-1
TS ^ N
BIODEGRADATION
1
ADSORPTION
« 	
DESORPTION
BIOACCUHULATION




'^Sp^
DISSOLVED

BIOTA
SENSITIZED
PHOTOLYSIS
P ARTICULATE

HYDROLYSIS
ADSORP
DESORPTION

* 	 1
L^«>4J
DEPURATION 1
< 	

01

PARTKULATE

POLLUTANT
TION

E-BI
TEJ '


^ACCUMULATION
SEDIMENTATION

-BIODEGRADATION

                                                                          * DAUGHTER PRODUCTS
                                                                           ALSO SUSCEPTABLE TO
                                                                           CHEMICAL PROCESSES
3-25
                       Exhibit 3.5-1 (reprinted from H7)

    This study has identified over thirty different surface water
models representing a variety of water body categories, temporal
scales, and dimensions.  Other identifying characteristics of surface
water models include the type of contamination source, such as

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Relationship to
OSWER Programs
Key Surface Water
Research
Organizations and
Modeling Centers
Findings
Model Developmen t
                        non-point surface runoff or point sources, and the processes
                        modeled, such as water flow, contaminant transport, or
                        contaminant exposure.
                            Surface water models can be valuable tools for performing
                        analyses for both RCRA and Superfund programs.  In cases
                        involving illegal dumping or accidental discharges of hazardous
                        wastes, there may be direct impacts on surface waters.  Even for
                        many land-based containment and remedial actions, analysts must
                        often account for surface water runoff.  For example, when
                        applying for permits under RCRA, TSD facilities must show that
                        surface water runoff from their sites will not pose any danger to
                        humans or the environment.
3-26
                            There are a variety of ORD organizations involved in the
                        development of surface water models and related research,
                        including the Environmental Research Laboratories (ERLs) at
                        Athens, Cincinnati, Narragansett, and Duluth, and the
                        Environmental Monitoring and Systems Laboratory in Las Vegas.
                        Historically, Athens-ERL has been the lead organization for
                        developing and supporting surface water models and conducting
                        related research. Athens-ERL's Center for Exposure Assessment
                        Modeling (CEAM) supports five surface water toxicant models:
                        WASP4, EXAMS H, HSPF9, SARAH,and DYNTOX It also supports
                        QUAL2E, a conventional pollutant model, and DYNHYD4, a
                        hydrodynamic model  (see Section 3.2 for a more complete
                        description of the types of services provided by Athens - ERL).
                        CEAM evolved from the former Center for Water Quality
                        Modeling, which was also housed at Athens.
    The findings presented below have been synthesized from the
project team's interviews and the review of several reference
documents on surface water modeling (see Appendices B and C).

    Surface water models are developed by a variety of
organizations, including EPA and other Federal agencies such as
NOAA and the Department of Agriculture, national research
laboratories such as Oak Ridge, universities/ and private
companies.  No widely recognized guidelines exist for the
development  and validation of surface water models.

    The computing environments for the surface water models
identified so far  are similar to most other categories. Models have
historically been developed in FORTRAN, primarily on IBM

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                         mainframes.  The current trend is a move towards microcomputer-
                         based models which can be more widely used.

Model Usage and             Several guidelines partially addressing the selection and
Support                 application of surface water models have been produced by EPA in
                         recent years.  These include Modeling Remedial Actions at
                         Uncontrolled Hazardous Waste Sites and Selection Criteria for
                         Mathematical Models Used in Exposure Assessments. Surface
                         Water Models.  These guidelines address the issues of proper
                         model selection, application, and on-site validation.  Also provided
                         are case studies of example applications.

                              Surface water models are not used extensively by OSWER
                         program staff.  They tend to be applied only in special cases.  No
                         clearinghouses, user support groups, bulletin boards, or training
                         programs were identified as supporting surface water modelers.
3-27

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Section  3.6.
Drinking  Water Modeling
Size and Scope
Relationship to
OSWER Programs
Key Drinking Water
Research
Organisations and
Modeling Centers
                            One drinking water model relevant to OSWER programs,
                        known as the Packed Column Air Stripping Model, has been
                        included in the Models Inventory.  This model has been used in
                        determining the feasibility of air stripping for controlling
                        moderately volatile synthetic organic chemicals (VOCs). It models
                        the engineering process of air stripping VOCs from drinking water.
                        Numerous other drinking water models oriented to engineering
                        aspects of drinking water systems have been developed, but this
                        model has the greatest potential for use by OSWER programs.
                            Drinking water models relate to RCRA and CERCLA
                        programs in two areas: engineering and risk assessments. For
                        example, remedial actions at Superfund sites sometimes require
                        the use of an air stripper for the treatment of water. Drinking
                        water related engineering models can be used to estimate the
                        amount of hazardous effluent which may be produced during a
                        clean-up effort.  Drinking water quality models may also be used in
                        exposure and risk assessments of TSDs regulated under RCRA.
                            There is no designated "lead" organization for drinking water
                        models.  The Technical Support Division of the Office of Drinking
                        Water, Cincinnati, has been the key organization involved in
                        applying the Packed Column Air Stripping Model. Other EPA
                        organizations involved with drinking water research and model
                        development include the Risk Reduction Engineering Laboratory,
                        Cincinnati, the Environmental Monitoring Systems Laboratory,
                        Las Vegas, the Robert S. Kerr Environmental Research Laboratory,
                        Athens, and the Health Effects Research Laboratory, Research
                        Triangle Park.
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Findings
                             Other than the use of the Packed Column Air Stripping Model
                         at certain Superfund cites, OSWER programs do not make heavy
                         use of drinking water models. No forums for the distribution or
                         support of drinking water models were identified.  No specific
                         examples of OSWER related applications of drinking water models
                         were provided.
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Section  4.           Review of Management Issues
                        This section presents six major management issues in a logical
                        sequence.  These issues were identified through several meetings
                        with members of the Hazardous Waste / Superfund Research
                        Subcommittees from OSWER and ORD and through the project
                        team's analysis of the information presented above in Sections 1, 2
                        and 3. The six management issues are:

                        •  Issue #1:  What is the relative importance of models in
                                      supporting hazardous waste / Superfund program
                                      activities?

                        •  Issue #2:  Is formal guidance on modeling necessary? If so,
                                      how should the guidance be developed and by
                                      whom?

                        •  Issue #3:  How should OSWER and ORD manage model
                                      development, calibration, verification, and
                                      validation?

                        •  Issue #4:  What types of standards should be imposed on
                                      hardware and software?

                        •  Issue #5:  How should model selection and application be
                                      occurring in the field?

                        •  Issue #6:  What types of user support organization and
                                      products should be created for model users?

                        For each issue, key project findings are recounted, a preliminary
                        conclusion is drawn, and alternative action items are suggested.
                        The recommendations presented in Section 3 are based on  the
                        review of these issues.
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Issue #1:   What is the relative importance of models
             In supporting hazardous waste /
             Superfund program activities?
Key Findings:

•   Hundreds of computerized/ numerical models are available,
     for many different processes and environmental media.

•   In cases where collecting monitoring data is technically
     difficult and too costly to provide the sole basis for exposure
     assessment the use of models, either alone or in combination
     with monitoring results, provides for reasonably informed
     predictions about environmental processes.

•   The need for models is generally acknowledged by program
     managers, engineers, scientists, and the legal community.
     Some managers are generally supportive of modeling,
     allowing their staff to spend time using models and acquiring
     necessary expertise. Other managers feel that modeling takes
     too much time away from day-to-day activities such as writing
     permits and performing inspections.

•   Actual model usage levels are unknown, and there are no
     mechanisms in place to keep track of performance of
     particular models in the field.

Preliminary Conclusion;

In hazardous waste /  Superfund programs (HW/SF), models are
not the only tools for supporting program decisions, but models are
sufficiently important decision-making tools that a coordinated
management strategy  for modeling is necessary. Inappropriate use
of models results in wasted time and effort, ineffective
enforcement and remediation,  and in some cases, embarrassments
for the Agency.  The value of models and the importance of
appropriate model use need to  be articulated by all levels of EPA
management.  Managers, in turn, must provide their staff with
dear direction on modeling and its relationship to other program
activities.

Related Action  Items;

•   Increase awareness of senior managers (e.g., Assistant
     Administrators, Division Directors, Office Directors, Regional
     Administrators) about modeling issues, develop a
     management strategy, and obtain key endorsements
     supporting the use of models and emphasizing the

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                             importance of applying models in a valid and consistent
                             manner.

                             Maintain dialogue with Science Advisory Board on their
                             Agency-wide modeling resolution.

                             Initiate discussions with other offices which may be helpful in
                             managing /supporting modeling at an Agency level (e.g.,
                             ODRM/NDPD and the Agency-wide Technology Transfer
                             Staff).
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                        Issue #2;   Is forma/ guidance on modeling
                                     necessary?  If so, how should the
                                     guidance be developed and by whom?
                        Key Findings;

                        •   There are no mandatory or recommended models for OSWER
                             programs.

                        •   Guidance on model selection and application is very limited;
                             some is being developed for the use of air models at
                             Superfund sites.

                        •   Some users oppose the establishment of strict model selection
                             standards and lists of prescribed models. They claim flexibility
                             is very important because of wide ranges of variation in site
                             characteristics and regulatory scenarios.

                        Preliminary Conclusion:

                        Guidance on modeling in HW/SF programs is necessary.  The
                        guidance should be flexible, and it should be modular, addressing
                        the needs and multiple perspectives of those who will be affected.
                        Guidance on modeling should focus on core areas such as
                        development of algorithms and computer code, but it should also
                        recognize the importance of data collection and quality assurance
                        in the modeling process.  Guidance will be valuable in at least three
                        areas:  development, verification and validation (V&V) (primarily
                        for modelers); hardware and software standards (primarily for
                        modelers); and model selection and application (primarily for
                        users).

                        Related Action Items:

                        •   Convene a group of modeling experts from different
                             disciplines and organizations to prepare guidance on model
                             development and V&V.  The guidance will be applicable to all
                             models targeted for use in HW/SF programs, and should
                             describe the model development, calibration, verification, and
                             validation processes for all types of models, addressing
                             differences among media where necessary.  (See Issue #3
                             below.)

                        •   Consult with OIRM and information  management groups in
                             other program offices about the need to develop standards for
                             hardware and software. Determine which types of standards
4-4                          are desirable and feasible. (See Issue #4 below.)

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                             Establish a group of RCRA and CERCLA program experts and
                             selected modeling experts from each major modeling
                             discipline to develop guidance on model selection and
                             application.  The guidance should include descriptions of
                             recommended models for different media and different types
                             of program decisions.  (See Issue #5 below.)
4-5

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                         Issue #3:   How should OSWER and ORD manage
                                      model development, calibration,
                                      verification, and validation?
                         Key Findings:

                         •   Development procedures have been discussed extensively, but
                             there is no universal agreement on "the right way" to develop
                             models. There are no standard peer review procedures for
                             models.

                         •   Most modelers agree on what verification is — in order for any
                             model to be credible/ the developer must verify that the code
                             performs its calculations  and uses its equations as intended.

                         •   Validation is more subjective because there are only degrees of
                             validity.  It is rarely possible to  do a complete validation effort
                             - it takes too much time and costs too much. For some
                             models, it is necessary to re-validate models with field data
                             every time they are applied.

                         Preliminary Conclusion:

                         Previously, discussion of standard modeling procedures has
                         occurred in a specific media context (e.g., ground water modeling,
                         air modeling).  Validation is one of the most controversial areas,
                         but in this area as well as others, it should be possible to get
                         modeling experts in  different  domains to reach consensus on a
                         typical "life-cycle"  for a model.  The fundamental objective for
                         guidance in the area of development, calibration, and V&V is to
                         establish an agreed upon set of procedures for testing and review
                         that will provide users with models  of known quality and
                         performance characteristics. Strengthened guidance in this area
                         will minimize the likelihood that models used by EPA will be
                         declared inaccurate or invalid in legal disputes with the regulated
                         community.

                         Related Action Items;

                         •   Develop guidance in this area focusing primarily on model
                             developers (e.g, ORD labs, contractors). Such guidance should
                             describe the model development process, or life-cycle, in
                             general terms. Resolution of controversy on the issue of
                             validation should be based upon the principles of Data Quality
                             Objectives (DQO).
4-6

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                             Assess need to coordinate with other organizations involved
                             in environmental modeling (e.g., NOAA, USGS, USDA,
                             American Meteorological Society).

                             Specify requirements for peer review for all models intended
                             for use in OSWER programs.

                             Obtain endorsement of this guidance by leading modelers in
                             different fields and top level OSWER and ORD managers.
4-7

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                         fssue  #4;   What types of standards should bo
                                      imposed on hardware and software?
                         Key Findings:

                         •   Modelers are actively applying new computing technologies
                             in developing their models, including a variety of hardware
                             platforms and software packages.

                         •   User interfaces, data input facilities, and programming styles
                             vary widely from model to model.

                         •   Many models are developed outside of EPA, making it
                             difficult to tightly control hardware and software.

                         Preliminary Conclusion:

                         Setting strict hardware and software standards will impose
                         constraints on model developers and may be difficult to enforce
                         (e.g., for third-party developers). Different types of standards may
                         be appropriate for model developers vs. model users.

                         Related Action Items;

                         •   Develop hardware and software standards, considering the
                             need for different standards for model developers and end
                             users.

                         •   Stipulate when standards apply (e.g., for cases where EPA is
                             funding the development of a model for a particular
                             "intended use") and link to guidance on model development.

                         •   Address need for ensuring that model distributors provide
                             software of the highest possible quality - i.e., standard
                             procedures for making updates, testing codes, and promoting
                             similar programming styles and practices.
4-8

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                          Issue #5:   How should model selection and
                                       application be occurring in the field?
                          Key Findings;

                          •   Some users lack the technical background to know which
                              models are optimal for certain types of analyses.

                          •   Staff do not always fully understand how their contractors or
                              the regulated parties are using models; contractors are heavily
                              involved in model selection and application.

                          Preliminary  Conclusion;

                          There is a need for guidance on model selection and application
                          that is both media-specific (e.g., groundwater, surface water, air)
                          and program activity-specific (e.g.,  RCRA Corrective Action,
                          Superfund RI/FS). In some cases, there may be no substitute for
                          direct communication (e.g., via a hotline) between the user and the
                          model expert. There is a need for a more precise way to categorize
                          models.

                          Related Action Items;

                          •   Conduct a study of how contractors are using models in
                              HW/SF programs, and ensure that contractors are selecting
                              models appropriately.

                          •   Assess various options for providing guidance on model
                              selection and implement the most cost-effective solution.
                              Identify proportions of cases where different types of guidance
                              are most effective — e.g., written guidance vs. automated
                              systems vs. direct consultation with experts.

                          •   As stated under Issue #3, ensure that Data Quality Objectives
                              are considered as part of the selection process — i.e., a model
                              should be selected before data  is collected, not vice versa.
4-9

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                         Issue #6:   What types of user support organization
                                      and products should be created for model
                                      users?
                         Key Findings;

                         •   Staff need readily available support and the backing of their
                             management in order to use models effectively.

                         •   Different types of support are needed: (1) scientific and
                             engineering expertise on models; (2) computer expertise on
                             how to run models; and (3) programmatic expertise on how to
                             make decisions based on model output.

                         •   Model usage is limited by significant entry barriers - input
                             data is often not available, data takes too much time to enter,
                             or model documentation does not provide adequate or
                             understandable explanations.

                         •   High turnover in Regional  offices creates  constant need to
                             train new staff.

                         Preliminary  Conclusion:

                         The focus of  user support should be on meeting the training and
                         technical support needs of the Regional offices and their
                         contractors.  There is a need for better communication channels
                         between Headquarters (HQ), ORD, Regional office staff, and
                         Environmental Service Divisions (ESDs).  ORD should play a
                         major role in user support.  Existing modeling centers should be
                         strengthened and new centers established with incentives to pro-
                         actively communicate with users to document field experiences
                         and maintain "audit trails" for models.

                         Related Action Items:

                         •   Establish a centralized modeling support group that can
                             interact  directly with OSWER program users in the Regions
                             and at Headquarters.  Ensure that this group has sufficient
                             resources to provide immediate response  to Regional needs
                             and has well-established communication  channels with
                             modeling experts for various media.  Provide members of this
                             group with incentives for pro-actively supporting model users
                             and maintaining a track record of performance for specific
                             models.
4-10

-------
                              Encourage Regional offices to create modeling groups that
                              provide support for running models for a variety of program
                              activities and communicate regularly with ORD modeling
                              centers and OSWER support groups.  Consult with Regions
                              that have formally or informally established these types of
                              groups (e.g., Regions HI and IV) to identify critical success
                              factors for this approach.

                              Ensure effective dissemination of information to model
                              developers and users through the issuance of newsletters,
                              maintenance of a models dearinghouse(s), and use of
                              electronic bulletin boards.
4-11

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Section  5.            Recommendations
                             These recommendations are designed to improve the
                         management and use of models for HW/SF programs in the most
                         effective and efficient manner possible, addressing many of the
                         management issues presented above in Section 4.  The
                         recommendations consist of a three-part action plan, incorporating
                         many of the action items identified in Section 4. The three major
                         task areas in the action plan are:

                         •   Task Area 1: Initiation, Additional Study, and Preparation of
                             Management Plan

                         •   Task Area 2: Development of Guidance for Modeling

                         •   Task Area 3: Establishment of User Support Network for
                             HW/SF Modeling

                             Each of these is described below. Figure 5-1 provides an
                         overview of the tasks,  responsibilities and suggested sequence of
                         events.  Figure 5-2 provides initial  resource estimates for
                         completing these tasks.

                         Task Area 1:  Initiation, Additional Studies, and
                         Preparation of Management  Plan

              Task 1.1.  Brief OSWER and ORD senior management on results of the
                         Models Study. The objectives for this briefing are to describe past
                         activities and project highlights, and to obtain top-level
                         endorsement for future plans, commitment of resources, and
                         clarification of roles and responsibilities.

                         Responsibilities, Products:  The OSWER Information
                         Management Staff (IMS) will coordinate the preparation and
                         presentation for these  briefings, coordinating with other OSWER
                         and ORD offices as necessary. Two products  are envisioned for this
                         task:  (a) briefing slides and other materials necessary to summarize
                         the results of the Models Study; and (b) a policy statement or
                         similar document, issued by the OSWER and ORD AA's offices,
                         endorsing this new effort to manage and use models more
                         effectively and  outlining key roles  and responsibilities. The
                         recipients of this memorandum will include Regional
                         Administrators, HQ Office Directors, and HQ and Regional
                         Division Directors.
5-1

-------
                                         Figure 5-1
                                Overview of Action Plan

Task Area 1
1.1 Management Briefings
1.2 Study of Model Use
1.3 Management Plan
Task Area 2
2.1 Model Development,
Verification and
Validation Guidelines
f-
2.2 Computing Alternatives
Manual
2.3 Selection Guide
Task Area 3
3.1 Establish Regional
Modeling Groups
3.2 Define Roles, Working
Agreements for
Modeling Centers
3.3 Create OSWER Modeling
Support Group
Weeks from Start-up
8 16 24 32 40 48 56
H£-A
Ij^^^^j^^^^L
^•wk m^^^
I-A-A
I ±_





Organizations
OSWER
L
L
L
L
L
P
P
L
ORD
P
L
L
ROs
P
P
P
L
P
  Key:
        Briefings, Meetings
        Draft Deliverable
L
P
             Deliverable
        Milestone
        Lead
        Participant
5-2

-------
                                               Figure 5-2

                                   Initial Resource Estimates

Task Area 1
1.1 Management Briefings
1.2 Study of Model Use
1.3 Management Plan
Task Area 2
2.1 Model Development,
Verification and
Validation Guidelines
2.2 Computing Alternatives
Manual
2.3 Selection Guide
Task Area 3
3.1 Establish Regional
Modeling Groups
3.2 Define Roles, Working
Agreements for
Modeling Centers
3.3 Create OSWER Modeling
Support Group
Weeks from Start-up
8 16 24 32 40 48 56
^
\-&r±
Subtotal
1 	 A 	 A
1 f V ^L
h-iV-A
Subtotal
I 	 ^
i _ 	 ., 	 ^
1 «™
Subtotal
Resources*
FTIis
.05
.05
.06
.16
.17
.17
.16
.5
6-15
8-10
2-3
16-28
$K
5-7
35-40
12-15
52-62
100-
150
40-45
100+
240-
295+
TBD
TBD
TBD
TBD
FY
89
89
89
90
90
90
91/92
91/92
91/92
  Notes:
      All estimates provided here are initial resource estimates only. More detailed
      estimates for Task Areas 2 and 3 will be developed under Task 1.3, the OSWER/ORD
      Management Plan for Models.  Estimates provided here are for the tasks specified
      in the proposed Action Plan; overlap with other initiatives has not been fully
      considered.
  * *  TBD=To Be Determined
5-3

-------
5-4
               Task 1.2.  Complete an in-depth study of actual model usage in HW/SF
                         programs, focusing on Regional users and contractors. This
                         study will build upon the information already gathered for the
                         models study, including the national survey of modeling
                         conducted by Region V for the Groundwater Workstation.  The
                         study will include an historical review of cases where modeling
                         has had significant resource impacts, both in terms of savings
                         attributed to the use of a model and costs of applying models and
                         performing V&V. Court cases involving disputes over models
                         will also be reviewed, and the Office of General Counsel will be
                         consulted to identify major legal issues related to modeling.
                         Another key component of this study will be the identification of
                         options for enhancing the skills and training Regional users.

                         Responsibilities, Products:  The OSWER Information
                         Management Staff will be the lead organization for this study.
                         Regional offices will participate in this study by supplying
                         information about their usage of models and providing contacts for
                         contractors. The product will be a report providing an in-depth
                         analysis of Regional needs for models training, and identifying the
                         most commonly used models on a program-by-program and
                         media-by-media basis.

                         Responsibilities, Products:  The OSWER Information
                         Management Staff will work with ORD to develop the OSWER
                         Management Plan for Models.  The plan will specify roles and
                         responsibilities, resource requirements, and detailed time lines.
                         Task Area 2:   Development of Guidance for Modeling

               Task 2.1.  Develop Guidelines for Model Development, Calibration,
                         Verification, Validation, and Peer Review. This guidance will
                         address two types of models: (a) new model development efforts
                         that are funded by OSWER or targeted for OSWER use; and (b)
                         existing models that are being modified for use by OSWER
                         programs.  The target audience for this guidance is model
                         developers, within EPA and outside the Agency, who wish to
                         promote their models for use in OSWER  programs.  The resulting
                         guidance document will describe a typical model "life-cycle,"
                         addressing relevant differences for models in various media.  Peer
                         review requirements  will be specified, including acceptance criteria
                         for models (e.g., public domain software, documentation
                         standards). For validation, particular attention will be paid to data
                         collection issues and  the relationship between validation and Data
                         Quality Objectives (DQO).

                         Responsibilities, Products:  ORD will take the lead on developing
                         Guidelines for Model Development,  Calibration, Verification,

-------
                         Validation, and Peer Review. The guidelines will be general
                         enough to apply them to models for different media and pathways.
                         Whenever possible, these guidelines will build upon existing
                         documents addressing these issues, including direct references to
                         other appropriate material.

              Task 2.2.  Develop a Manual on Alternative Computing Technologies for
                         HW/SF Models. This manual will directly complement the
                         guidance developed under Task 2.2, providing model developers
                         with information on the current and future state-of-the-art in
                         computing approaches for models. The current OSWER and
                         Agency-wide computing environments will be described in order
                         to ensure that model developers understand hardware and
                         software constraints from different perspectives (e.g., OSWER,
                         ORD, OIRM/NDPD, and Regional offices). The manual may be
                         supplemented with periodic "Technology Updates," issued
                         semiannually or annually. The manual may also include
                         descriptions of  various "recommended" computing approaches
                         and suggestions for maintaining model codes and distributing
                         updated software.

                         Responsibilities, Products: The OSWER Information
                         Management Staff  will develop the Manual on Computing
                         Technologies for Modeling.  Model developers from ORD and
                         other sources will provide input for this manual.  The Office of
                         Information Resources Management (OIRM) will assist in
                         reviewing the documents and provide information on Agency-
                         wide computing trends.

              Task 2.3.  Develop a Selection and Application Guide for Models in
                         Hazardous Waste / Superfund Programs.  This guidance will be
                         focused on model users in the Regional offices. The Guide will
                         provide both a media and program orientation so that the user can
                         easily locate information on models that are appropriate for a
                         particular type of analysis and a particular program decision. The
                         effort to develop this Guide will include an in-depth review of the
                         Models Inventory by modeling experts and OSWER program
                         experts; the purpose of this will be to identify a subset of preferred
                         or appropriate models in various categories.

                         Responsibilities, Products:  The OSWER Information
                         Management Staff  will work with the OSWER Technology Staff
                         and appropriate ORD offices to establish a multidisciplinary project
                         team to develop the Selection and Application Guide for Models in
                         HW/SF programs.  Development work will be coordinated with
                         related ORD and OSWER initiatives (e.g., ATTIC, OTTRS1
                         Information Clearinghouse, OSWER1 s Technology Support
                         Project). The Guide may either take the form of an automated
                         reference tool (e.g., an expert system) or a paper-based "modeler's
                         desk reference."  The development team will include experts on
                         models and OSWER program experts, and may include system
i-_i-                      development personnel if an automated tool is chosen.

-------
                         Task Area 3:   Establishment of User Support Network
                         for Hazardous Waste / Superfund Modeling.

                             Figure 5-3 provides an overview of the user support network
                         described below under Tasks 3.1, 3.2, and 3.3.

               Task 3.1.  Establish a Network of Regional Modeling Groups (RMGs).
                         These groups will act as a service bureau, providing a central pool
                         of modeling expertise in each Region. The RMGs will be staffed by
                         individuals with expertise in specialty areas (e.g., ground water, air,
                         computer skills), who may be drawn from programs outside the
                         Waste Management Division. The members should have a
                         portion of their time dedicated to fulfilling their RMG roles. The
                         RMGs will communicate directly with the ORD Modeling Centers
                         and the OSWER Modeling Support Group (see below). ORD will
                         provide the RMGs with scientific and technical expertise on how to
                         use models, how to interpret results, and ORD will educate users
                         on the assumptions of the models.  OSWER will provide the
                         RMGs with guidance on selecting the most appropriate model for a
                         particular regulatory scenario and will assist the users in addressing
                         policy and  legal issues related to the use of a model.

                         Responsibilities, Products: The Regional Offices, through the
                         Waste Management Division, ESDs, and other Program Divisions,
                         will have the lead for establishing the RMGs. OSWER will
                         coordinate  with the Regional Offices and define relationships
                         between the RMGs, the ORD Modeling Centers, and the OSWER
                         Modeling Support Group (see below). The RMGs will meet on a
                         regular basis to discuss modeling issues, and they will actively
                         communicate with their counterparts in other Regions.

                         Task 3.2.  Define Roles and Working Agreements  With ORD
                         Modeling  Centers. The Centers should have a media orientation,
                         reflecting the strengths of different labs in different media.  The
                         Centers will be the primary source of scientific and technical
                         support for Regional model users.  They will develop models,
                         modify codes, add enhancements, conduct training courses, consult
                         with users  about specific modeling applications, and pro-actively
                         monitor the field performance of the models they are supporting.
                         Model developments in emerging areas  such as exposure
                         assessment should be encouraged within the context of this media-
                         based organization (e.g., exposure assessments for surface water
                         pathways). Each Center should develop its own expertise in
                         multimedia and  exposure assessment modeling, focusing
                         especially on linking the Center's models for one media with  those
                         of a different media. The activities under this task should be
                         coordinated with establishment of other  types of ORD support for
                         OSWER (e.g., the Alternative Treatment Technologies Information
                         Clearinghouse).
5-6

-------
                                     Figure 5-3
            User Support Network for  HIV / SF Modeling
         OSWER Modeling
          Support  Group
              (OMSG)
      OMSG conveys
      program needs for
      new models to ORD,
      works with ORD to
      develop training courses,
      and refers user requests to
      appropriate ORD experts.
      ORD provides peer review,
      supports OMSG in developing
      guidance on model selection.
 OMSG supports RMGs
in resolving policy and
 legal issues related to
modeling; includes dis-
seminating information
an providing guidance
  on model selection.
                                                         _L
   Regional
   Modeling
Groups (RMGs)
                                  ORD provides
                                technical and/or
                             scientific support for
                            RMGs; includes model
                          documentation, training,
                          hotline support for users,
                       consulting, and code changes.
                       RMGs report on performance
                    attributes of models in the field.
ORD Modeling Centers


Air
Multimedia
and Exposure
Assessment

Surface
Water
Multimedia
and Exposure
Assessment

Ground
Water
Multimedia
and Exposure
Assessment

Drinking
Water
Multimedia
and Exposure
Assessment


            Science Advisory Board Resolutions on Agency-wide Modeling
5-7

-------
                         Responsibilities, Products: ORD, through the HW/SF Research
                         Committee/ will establish the Modeling Centers, refining the
                         charters of existing modeling centers as necessary to address
                         OSWER's modeling needs.  The role of these Centers is to be the
                         "keepers of the code" and the home of modeling experts for a
                         particular medium. They will respond to support requests from
                         RMGs and well as OSWER (see  3.3 below). The Centers will
                         produce new and revised models, documentation, technical
                         assistance, and training.

               Task 3.3.  Create an OSWER Modeling Support Group (OMSG). This
                         group's mission is two-fold.  First, it will be primarily responsible
                         for managing the development  of guidance materials on modeling
                         and disseminating this information to users.  OMSG will be a
                         liaison between the ORD Modeling Centers and the RMGs, and its
                         staff will be knowledgeable about all of the modeling guidance
                         products described in Task Area 2. Second, it will provide RMGs
                         and other users with specific policy and legal advice on model
                         applications. This includes reporting on significant policy and legal
                         events that affect the future use  of models (e.g., court cases, new
                         regulations)

                         Responsibilities, Products: OSWER will take the lead in
                         establishing OMSG, coordinating with related OPMT initiatives
                         (e.g, the Technology Support Project, Groundwater Workstation).
                         OMSG products will include information dissemination tools such
                         as the OSWER Data Resource Directory, a models clearinghouse, an
                         electronic bulletin board, or a periodic modeling newsletter.
5-8

-------
  Appendices
A:   Interview Guide
B:   Interview List
C:   Bibliography
D:   OSWER Models Inventory
     Abbreviated

-------
                                 Appendix A
                            Interview Guide
•     Information About the Interviewee
            Name, organization, etc.
      ~     Major activities of your organization
      ~     Involvement in  modeling activities

•     Please describe any models used by you or your organization.
      —     Name of Model
            Contact Person
            Model Supports Which Program(s)?
            Functional Description
                 application area
                 data used for input
                 end products
            Technical Description
                 hardware and software
                 documentation
                 assumptions and constraints
                 types of calculations performed
      Please outline the key milestones in model building in your organization from
      inception through validation through use through termination. For a typical
      modeling project, discuss the following:
      ~    staffing requirements?
      —    relationship and communication with program offices?
           research and technical work?
A-1

-------
      —     review cycles?

      On which steps in the life cycle does your work focus?



      How consistent are modeling activities in terms of:

      —     development  approach?

      —     tools (i.e., hardware and software)?
•     Does your group have any guidelines for model development? Do you know of any
      guidance documents?

—     If not, how do you approach the modeling effort?

—     If so, are the procedures followed? Which aspects are particularly valuable or not
      valuable?
      Where are the key bottlenecks or milestones which are difficult to traverse and
      why? Where are the greatest difficulties encountered?

      -     research?

      -     development?

      —     implementation?

            use and interpretation?
      What are your suggestions for improvements to the modeling process in your
      organization which would increase the quality and timeliness of models while
      decreasing the cost and bureaucratic requirements?
•     What is the best example of a successful model and why was it successful?
      What attributes make some models unsuccessful? How can these pitfalls be
      avoided?
A-2

-------
•     Whom do you talk with or where do you go for information, assistance, or review
      of your modeling efforts?
      What results would you like to see from this effort?
A-3

-------
                               Appendix B
                           Interview List
1.    Interviews at EPA-HO (Washington. DC)

                    Office of Research and Development
           Name                  Date                 OfiFice
     Tom Baugh                 11/30/88             OMMSQA
     Ray Thacker                 11/17/88             OEETD
     Will LaVeille                12/8/88              OEPER
     Tom Miller                 12/2/88              OHR
     LeeMulkey                 12/15/88             A-ERL
     Anthony Donigian           12/15/88             Aqua Terra,
                                                     Inc.(for A-ERL)
     Doug Ammon               12/9/88              Clean Sites, Inc.
                                                     (formerly ORD)

                  Office of Solid Waste and Emergency Response
           Name
     Meg Kelly
     Rich Steimle
     Ron Wilhelm
     Bill Wood

     Larry Zaragoza
     Jennifer Haley
     Alec McBride
     Zubair Saleem
B-1
Date
1/26/89
11/18/88,1/26/89
2/13/89
11/30/88
11/18/88
12/2/88
12/6/88
12/7/88
Office
OPMT
OPMT
OPMT
Risk Assessment
Forum
OPMT
OERR
OSW
OSW

-------
      Interviews at Robert S. Kerr Environment Research Laboratory. ORD (Ada.
      OK)
      Name                       Date
      Joe Williams                 12/19/88
      Tom Short                  12/19/88
      Carl Enfield                  12/19/88
      Dick Scalf                    12/19/88
      Jim Mercer                  12/19/88              (GeoTrans, Inc.)
3.     Interviews at  International Groundwater Modeling Center. Holcomb
      Research Institute (Indianapolis. IN)
      Name                       Date
      Paul van der Heijde           12/20/88
      Stan Williams               12/20/88
4.     Interviews at Atmospheric Research and Exposure Assessment Lab (AREAL).
      ORD (Research Triangle Park. NO
      Name                       Date
      Gary Foley                   1/11/89
      Jack Shreffler                 1/11/89
      Bill Nelson                  1/11/89
      Bill Mitchell                 1/11/89
      Bill Peterson                 1/11/89
      Bruce Turner                 1/11/89

B-2

-------
5.     Interviews at Air and Energy Engineering Research Lab (AEERL), ORD
      (Research Triangle Park. NO
      Name                       Date

      Bill Linak                    1/11/89
6.     Interviews at Office of Air Quality Planning and Standards (OAOPS). OAR
      (Research Triangle Park. NO
      Name                       Date

      Joe Tikvart                   1/11/89

      Joe Padgett                   1/11/89
7.     Interviews at Athens Environmental Research Lab (A-ERL). ORD. including
      the Center for Exposure Assessment Modeling (Athens, GA)
      Name                       Date

      Bob Ambrose                1/12/89

      Dave Disney                 1/12/89               (CSC)

      Tim Wool                   1/12/89               (CSC)

      Craig Barber                 1/12/89

      Tom Barnwell                1/12/89

      Dave Brown                 1/13/89
B-3

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8.     Interviews at Risk Reduction Engineering Laboratory (RREL). ORD
      (Cincinnati. OH)
      Name                       Date
      John Convery                1/23/89
      Bob Landreth                1/23/89
      Dan Greathouse              1/23/89
      Richard Eilers                1/23/89
      Jim Goodrich                1/23/89
      Jeff Adams                   1/23/89
      C.C. Lee                      2/7/89               (via telephone)

9.     Interviews at Technical Support Division. ODW (Cincinnati. OH)

      Name                       Date
      Jim Westrick                 1/23/89
      Mike Cummins              1/23/89
10.    Interviews at Center for Environmental Research Information (CERI). ORD
      (Cincinnati. OH)
      Name                       Date
      Cal Lawrence                 1/23/89
      Clarence demons             1/23/89
      Fran Kremer                 1/23/89
      Orville Macomber             1/23/89
B-4

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11.    Region HI
      Name

      Mark Garrison


      John  Nevius



      Fred  Sturniolo



      Gail Carron



      Mike  Towle



      Joel Hennessey
Date

2/27/89


2/27/89



2/27/89



2/27/89



2/27/89



2/27/89
 Air Management
 Division

 Waste
 Management
 Division

 Waste
 Management
 Division

 Waiste
 Management
 Division

 Waste
 Management
 Division

 Waste
 Management
 Division
12.    Region V
     Name

     Carol .Witt
Date

2/8/89,
3/10/89
Region V, Waste
Management
Division (via
B-5

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                                Appendix C

                             Bibliography


Policv/Manaaement/Proaram  Issues


PI.   Briefing Slides on Modeling and Other Research at Athens ERL, November, 1988.


P2.   Conceptual Approach to Collecting and Managing Data for OSW, BAH.


P3.   "EPA's Ecological Risk Assessment Research Program, October 1985 - March 1988,"
           Environmental Research Brief, EPA Environmental Research Laboratory,
           Athens, Georgia, August, 1988.


P4.   EPA Research Program Guide, FY '89, Office of Research and Development,
           September, 1988, EPA/600/9-88/017.


P5.   RCRA Orientation Manual. OSW/OSWER, January, 1986.


P6.   "Resolution on the Use of Mathematical Models by EPA for Regulatory Assessment
           and Decision-Making" (Draft), Science Advisory Board, December, 1988.


P7.   "Selection, Application, and Validation of Environmental Models," presented at the
           International Symposium on Water Quality Modeling of Agricultural Non-
           Point Sources, A.S. Donigian, Jr., Logan, Utah, June, 1988.


P8.   Superfund Exposure  Assessment Manual


P9.   Superfund Risk Assessment Information Directory, OERR, November, 1986.


P10.   "Technology Support Project Guide for OSC/RPMs," Superfund Technology
           Support Project, Booz* Allen & Hamilton, Inc.


Pll.   "Technology Transfer and the EPA Library Network"


P12.   "U.S. EPA On-Scene Coordinator Communications and Computer Hardware and
           Software Needs: A Review," Meinhold, Moskowitz, Birnbaum, and Salgado,
           Brookhaven National Laboratory, OSWER, December, 1988.
C-1

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Ground-Water Models


Gl.   "Agency Procedures and Criteria for the Selection and Application of Groundwater
           Models/' OWPE, June 21,1985.


G2.   "Applying the USGS Mass-transport Model (MOC) to Remedial Actions by Recovery
           Wells/1 Aly I. El-Kadi, IGWMQ Indianapolis, Indiana, September, 1987.


G3.   Background Document on Subsurface Fate and Transport Model, July, 1988.


G4.   Compendium of Methods to Determine Contaminated Soil Response Action Levels
           Based on Potential Migration to Ground Water, OERR/OSWER (by BAH),
           November, 1988.


G5.   IGWMC Ground Water Modeling Newsletter, June, 1988.


G6.   General Information, International Groundwater Modeling Center, Butler
           University, Indianapolis, IN.


G7.   Groundwater Requirements Study, 1988, AMS.


G8.   "Groundwater Flow and Transport Modeling," Leonard F. Konikow and James W.
           Mercer, Reston, Virginia, December, 1987.


G9.   Groundwater Management;  the use of numerical models. (Second Edition) Paul
           van der Heijde, Yehuda Bachmat, John Bredenhoeft, Barbara Andrews, David
           Hotz, and Scott Sebastian, published by American Geophysical Union,
           Washington, DC, 1985.


G10.  "Groundwater Modeling: An Overview and Status Report," Paul K. M. van der
           Heijde, Aly I. El-Kadi, Stan A. Williams, IGWC, R.S. Kerr ERL, December,
           1988.


Gil.  Interactive Simulation of the Fate of Hazardous Chemicals During Land Treatment
           of Oily Wastes; RTTZ User's Guide. Robert S. Kerr Environmental Research
           Laboratory, Ada, Oklahoma, January, 1988.


G12.  International Projects in Validating Ground-Water Flow and Transport Models
           (Abstract), U.S. NRC and Sandia National Laboratories

C-2

-------
G13.  "Lessons Learned from Hydrocoin and Intraval," U.S. NRC, September 20,1988.


G14.  Model Assessment for Delineating Wellhead Protection Areas, Final Report, Paul
            K.M. van der Heijde and Milovan S. Beljin, IGWMC, Indianapolis, Indiana,
            July, 1987.


G15.  "A New Annotation Database for Groundwater Models," Paul K.M. van der Heijde
            and Stan A. Williams, IGWMC, Indianapolis, Indiana, February, 1987.


G16.  "NRC Experiences in Hydrocoin:  An International Project for Studying Ground-
            Water Flow Modeling Strategies," (Abstract) Thomas J.. Nicholson, Timothy J.
            McCartin, Paul A. Davis, and Walt Beyeler.


G17.  "OASIS: A Graphical Hypertext Decision Support System for Ground Water
            Contaminant Modeling," (Draft) Charles J. Newell and Philip B. Bedient,
            December, 1988.


G18.  "Price List of Publications and Services Available from IGWMC," IGWMC,
            Indianapolis, Indiana, December, 1988.


G19.  "Quality Assurance in Computer Simulations of Groundwater Contaminations,
            Paul van der Heijde, IGWMC, Holcomb Research Institute.


G20.  "Remedial Actions Under Variability of Hydraulic Conductivity," Aly I. El-Kadi,
            IGWMC, Indianapolis, Indiana, February, 1987.


G21.  Robert S. Kerr Environmental Research Laboratory: a description of the lab's history,
            current activities, organization, and publications; produced by ORD in Ada,
            Oklahoma; March, 1988.


G22.  "The Role of the International  Ground Water Center (IGWMC) in Groundwater
            Modeling," Paul K.M. van der Heijde, IGWMC, Indianapolis, Indiana, 1987.


G23.  Selection Criteria for Mathematical Models Used in Exposure Assessments:
            Ground-Water  Models, EPA,  Office of Health and Environmental
            Assessment, Washington, DC, May, 1988.


G24.  "Simulation of Biodegradation and Sorption Processes in Ground Water," P.
            Srinivasan and  James W. Mercer, Ground Water, July-August, 1988.
C-3

-------
G25.  "Standards of Performance for Investigative Methods Used in Assessing
           Groundwater Pollution Problems with Emphasis on the Use and Abuse of
           Numerical Models/' presented at the Water Pollution Control Federation
           Pre-Conference Workshop, James W. Mercer, GeoTrans, Inc., Herndon,
           Virginia, October, 1988.


G26.  Technical Assistance Directory, Groundwater Research, OEETD/ORD, March 27,
           1987.


G27.  'Testing, Verification, and Validation of Two-dimensional Solute Transport
           Models," Milovan S. Beljin and Paul K.M. van der Heijde, IGWMC,
           Indianapolis, Indiana, December, 1987.


G28.  U.S. EPA Ground-Water Modeling Policy Study Group: Report of Findings and
           Discussions of Selected Ground-Water Modeling Issues; Paul K.M. van der
           Heijde and Richard Park, International Ground-Water Modeling Center,
           Holcomb Research  Institute, Butler University; November, 1986.


G29.  The Use of Models in Managing Ground-Water Protection Programs; Joseph F.
           Keely, Ph.D., Robert S. Kerr ERL, U.S. EPA, Ada, OK; January. 1987.


Exposure Assessment Models


El.    Center for Exposure Assessment Modeling; Mr. Robert Ambrose, Jr., U.S. EPA ERL,
           Athens, GA


E2.    "Draft CEAM Policy on Support and Distribution of New Models"


E3.    "A Method for  Testing Whether Model Predictions Fall Within a Prescribed Factor
           of True Values, with an Application to Pesticide Leaching," Rudolph S.
           Parrish and Charles N. Smith, Environmental Research Laboratory, Athens,
           Georgia.


E4.    Report on Proceedings:  Aspects of Model Validation for Predictive Exposure
           Assessment, Risk Assessment Forum Colloquium, ORD, September 20,1988.


E5.    "Technical Support to Office of Solid Waste and Emergency Response and EPA
           Regional Offices for Multimedia Exposure Assessment Related to Remedial
           Action, FY88," Robert B. Ambrose, Jr., November, 1988.
C-4

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E6.   User's Guide for PCGEMS. the Personal Computer Version of the Graphical
            Exposure Modeling System. U.S. EPA Environmental Research Laboratory,
            Athens, GA; August, 1988.


Air Dispersion Models


Al.   Environmental Research Brief: Description of UNAMAP (Version 6); D.Bruce
            Turner and Lucille Bender, U.S. EPA ERL, Research Triangle Park, NC;
            December, 1986.


A2.   Evaluation and Assessment of UNAMAP. R. Ernest Baumann and Rita K. Dehart,
            Battelle,  Washington, DC, February, 1988.


A3.   Federal Register; Environmental Protection Agency; 40 CFR Parts 51 and 52; "Air
            Quality Models Guideline"; SeptemberX 9,1986.


A4.   Guideline on Air Quality Models (Revised); U.S.  EPA Office of Air Quality Planning
            and Standards, Research Triangle Park, NC; July, 1986.


A5.   Handbook for Preparing User's Guides for Air Quality Models: William Petersen,
            John S. Irwin, D.  Bruce Turner, Meteorology and Assessment Division,
            Environmental Sciences  Research Laboratory, U.S. EPA, Research Triangle
            Park, NC; May, 1983.


A6.   "The NAAQS Exposure Model  (NEM) Applied to Ozone," (Draft) Roy A. Paul, Ted
            Johnson, Anne Pope, and Alicia Ferdo, PEI Associates, Inc., Durham, North
            Carolina, February, 1986.


A7.   "Procedures for Conducting Air Pathway Analyses for Superfund Activities,
            Volume  n, Estimation of Baseline Air Emissions at Superfund Sites," U.S.
            EPA Office of Air Quality Planning  and Standards, Research Triangle Park,
            NC, February, 1989.


A8.   "Procedures for Conducting Air Pathway Analyses for Superfund Activities,
            Volume in, Estimation of Air Emissions from Clean-up Activities at
            Superfund Sites,"  U.S. EPA Office of Air Quality Planning and Standards,
            Research Triangle Park, NC, January, 1989.


A9.   "Validation of the Simulation of Human Activity and Pollutant Exposure (SHAPE)
            Model Using Paired Days from the Denver, CO, Carbon Monoxide Field
            Study," Wayne Ott, Jacob Thomas, David Mage, and Lance Wallace, February,
            1987.

C-5

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Surface Water Models


SI.   "Development of a Prototype Expert Advisor for the Enhanced Stream Water
           Quality Model QUAL2E," Thomas O. Barnwell, Jr., Linfield C. Brown, and
           Wiktor Marek, September, 1986.


S2.   "Dynamic Estuary Model Performance/' Robert B. Ambrose, Jr. and Stephen E.
           Roesch, February, 1982.


S3.   Proceedings of Stormwater and Water Quality Model Users Group Meeting (March
           23-24,1987, Denver, CO); ed.by William James, University of Alabama, and
           Thomas Barnwell, Jr., Center for Water Quality Modeling, U.S. EPA
           Environmental Research Laboratory, Athens, GA; August, 1987.


S4.   Selection Criteria for Mathematical Models Used in Exposure Assessments; Surface
           Water Models. EPA, Office of Health and Environmental Assessment, July,
           1987.


Drinking Water Models


Dl.   "Feasibility of Air Stripping for Controlling Moderately Volatile Synthetic Organic
           Chemicals," Michael D. Cummins, James J. Westrick, and US EPA Office of
           Drinking Water.


D2.   "Packed Column Air Stripping Cost Model," Michael D. Cummins and James J.
           Westrick, June, 1988.


D3.   "Packed Column Air Stripping Preliminary Design Procedure," Michael D.
           Cummins and James J. Westrick, presented at 1986 Water Pollution Control
           Federation Conference, October, 1986.


Hazardous  Waste Engineering


HI.   "Bioremediation of Hazardous Waste Sites Workshop," a workshop brochure, EPA,
           Center for Environmental Research Information, Cincinnati, Ohio.


H2.   A Compendium of Technologies Used in the Treatment of Hazardous Wastes. EPA,
           Center for Environmental Research Information, Cincinnati, Ohio,
           September, 1987.
C-6

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H3.   Completed Interview Guide from Albert J. Klee, WMDDRD/RREL on the D-SSYS
            model.


H4.   Handbook, Remedial Action at Waste Disposal Sites (Revised), EPA, Office of
            Emergency and Remedial Response, Washington, DC, October, 1985.


H5.   "Hazardous Waste Management On the Occurrence of Transient Puffs in a Rotary
            Kiln Incinerator Simulator," William P. Linak, James D. Kilgroe, Joseph A.
            McSorley, Jost O.L. Wendt, and James E. Dunn.


H6.   "Mechanisms Governing Transients from the Batch Incineration of Liquid Wastes
            in Rotary Kilns," Jost O.L. Wendt and William P. Linak, June, 1988.


H7.   Modeling Remedial Actions at Uncontrolled  Hazardous Waste Sites.
            OERR/OSWER, April, 1985.


H8.   "Project Summary:  d-SSYS, A Computer Model for the Evaluation of Competing
            Alternatives," Albert J. Klee, EPA, Hazardous Waste Engineering Research
            Laboratory, August, 1988.


H9.   (Proceedings) Seminars — Requirements for Hazardous Waste Landfill Design,
            Construction and Closure Presentations, EPA, Center for Environmental
            Research Information, Cincinnati, Ohio, June,  1988.


H10.  "Waste Minimization  Workshop, An Opportunity to Promote Waste Minimization
            through Auditing and Process Analysis Procedures," a workshop brochure,
            EPA, Center for Environmental Research Information, Cincinnati, Ohio.


Hll.  Waste Minimization Opportunity Assessment Manual, EPA, Center for
            Environmental Research Information,  Cincinnati, Ohio, July, 1988.


Information Technology


II.    "Advanced Computer Applications (ACA)", International Institute for Applied
            Systems Analysis (RASA), Laxenburg, Austria; March, 1988.


12.    "Center for Advanced Decision Support for Water and Environmental Systems",
            University of Colorado, Boulder, CO.
C-7

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                                Appendix D

            OSWER Models Inventory - Abbreviated

Background

      The OSWER Models Inventory is a database containing information on models
identified by this study. The information is not focused on the technical aspects of the
model, but on usage and availability.  The database contains models from each
modeling category: Ground Water, Exposure Assessment, Air Dispersion, Surface
Water, Hazardous Waste Engineering, and  Drinking Water.  The information in the
database was gathered from both the interviews and the documents recommended to
the project team.

Type of Information in the Database

      The database contains a variety of information on each model, including:
      •     Name, including the formal name, acronyms, and aliases.
      •     Purpose, including the category, methods, and a text description.
      •     Computer environment, including type of hardware, software used, and
            available documentation.
      •     Developer information, especially who developed the model, where it
            was developed, and when it was completed or updated.
      •     Distributor data, specifically whether or not the model code is available,
            and a source  of distribution for the model and its documentation.
      •     EPA organizations in OSWER, ORD, or elsewhere which are known to
            have either used the model or supported its development.

Description

      The following lists of models were extracted from the OSWER Models database.
All of the model information  came from documents in the Bibliography (Appendix
C). These documents can be a source of further information on these models.

      Model Name, Full Name — uniquely identify the model.
      Purpose — gives a short description of the model's function and application
      Developer ~ describes who developed the model.
      Affiliation — identifies the organization of the developer.
      Distributor — gives a point-of-contact for the model when the software is
      available for distribution.
      Source ~ provides the name of an organization which has further model
      information when the software is not available for distribution.

For Further Information

      For further information on the OSWER Models Inventory, hardcopy or
database, contact Mary Lou Melley of the Information Management Staff, OPMT,
OSWER, 401 M St., SW, OS 110, Washington, DC, 20460, FTS 475-6760 ((202) 475-6760).
D-1

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Ground  Water Models
1.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

2.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

3.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

4.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

5.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

6.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

7.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: AGU-1

: saturated flow
; K.R. Rushton, LM. Tomlinson
: Dept. of Civil Engineering University of Birmingham
: IGWMC
: AGU-10
»

: solute transport
: I. Javandel, L. Doughty, C.F. Tsang
: IGWMC Holcomb Research Institute
: IGWMC
:AQSIM

: saturated flow
: D.A. Blank
: Tahal Consulting Engineers Ltd.
: IGWMC
:AQUIFEM
i

: saturated flow
:G.F. Finder, CLVoss
: U.S. Geological Survey Water Resources Division
: IGWMC
: AQUIFEM-1

: saturated flow
: L.R. Towney, J.L. Wilson, A.S. Costa
: Lab. for Water Resources & Hydroynamics, MIT
: IGWMC
; AQUIFER

: saturated flow
: B. Sagar
; Anaytic and Computational Research, Inc.
: IGWMC
; AQUIFLOW

: saturated flow
: G.T. Yeh, CW. Francis
: Environmental Sciences Division Oak Ridge National Laboratory
; IGWMC
D-2

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8.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

9.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

10.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

11.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

12.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

13.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

14.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: ASCOT

: solute transport
; A.B. Gureghian
: Office of Crystalline Respository Development Battelle Memorial Ins
: IGWMC
; ASSP
: AQUIFER SIMULATION SUBROUTINES PACKAGE
: multiphase flow
: Giesel, W., Schmidt, G., Trippler, K.
: Bundesanstalt fur Geowissenschaften und Rohstoffe
: IGWMC
:BACRACK

: fractured rock
: Strack, O. D. L.
; Battelle Pacific Northwest Laboratories
: IGWMC
: BALANCE

: hydrochemical
; Parkhurst, D.L., Plummer, L.N., Thorstenson, D.C.
: U.S. Geological Survey, Water Resources Division
: IGWMC
; BASIC GWF

: saturated flow
: A. Verruijt
: IGWMC, Holcomb Research Institute
; IGWMC
: BEAVERSOFT

: solute transport
: J. Bear, A. Verruijt
: IGWMC Holcomb Research Institute
; IGWMC
: BIDAT-HS2

: saturated flow
; P. Prudhomme, J.L. Henry, F. Biesel
: Laboratoire Central D'Hydraulique De France
; IGWMC
D-3

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15.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

16.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

17.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

18.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

19.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

20.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

21.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: BIO-ID
•

: solute transport
: P. Srinivasan, J.W. Mercer
: GeoTrans, Inc.
: IGWMC
; BURGEAP-1
: Burgeap 7600HYSO Package
: multiphase flow
: D'Orval, M. douet
: Burgeap
: IGWMC
; BURGEAP-2
; BURGEAP 7600HYSO (TRABICO MODEL)
: saturated flow
: M. Clouet, D'Orval
: Burgeap
: IGWMC
; BURGEAP-3
; BURGEAP 7600 HYSO (TRABISA MODEL)
: saturated flow
: M. Clouet, D'Orval
; Burgeap
: IGWMC
:CADIL

: solute transport
: C.J. Emerson, B. Thomas, R.J. Luxmoore
: Computer Sciences Oak Ridge National Lab.
: IGWMC
iCATTI

: solute transport
; J.P. Sauty, W. Kinzelbach
: IGWMC Holcomb Research Institute
: IGWMC
iCCASM
: Cape Cod Aquifer System
: multiphase flow
: Guswa, J. H., LeBlanc, D. R.
: U.S. Geological Survey
: IGWMC
Models
D-4

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22.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
:CFEST

: heat transport
: S.K. Gupta, C.R. Cole, C.T. Kincaid, A.M. Monti
; Water & Land Resources Division, Battelle Pacific NW Lab
: IGWMC
23.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
iCFTTIM

: solute transport
: M.Th. van Genuchten
: IGWMC Holcomb Research Institute
: IGWMC
24.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

25.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: CHAINT

; fractured rock
: Kline, N. W., England, R. L., Boca, R. C.
: Rockwell International, Rockwell Hanford Operations
: IGWMC
:CHARGR

: multiphase flow
: Pritchett, J. W.
: Systems, Science and Software
: IGWMC
26.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: CHEMRANK

: solute transport
: D.L. Nofziger, P.S.C. Rao, A.G. Hornsby
: Institute of Food & Agric. Sciences University of Florida
: IGWMC
27.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

28.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: COLUMN2

: solute transport
: O.D. Nielsen, P. Bo, L. Carlsen
: Chemistry Dept. Riso National Laboratory
 IGWMC
 CONS2-1D

 saturated flow
 C.S. Desai
 Department of Civil Engineering University of Arizona
 IGWMC
D-5

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29.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

30.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

31.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

32.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

33.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

34.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

35.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: CONSOL-1

: saturated flow
: K. Ueshita, K. Sato
 Dept. of Geotechnical Eng. Nagoya University
 IGWMC
: CONSP(L/NL)-2D

: saturated flow
: C.S. Desai
: Department of Civil Engineering University of Arizona
: IGWMC
:CRACK

: fractured rock
: Sudicky, E. A.
: Institute for Groundwater Research, Univ. of Waterloo
: IGWMC
:CRREL

: saturated flow
: CJ. Daly
: U.S. Army Corps of Engineers Cold Regions Research & Eng. Lab
: IGWMC
iCXTFIT
•     .

: solute transport
: J.C. Parker, M.Th. van Genuchten
: Dept. of Agronomy Virginia Polytechn. Inst. and State Univ.
: IGWMC
:DELPET
: DELPET-DISCRETE KERNEL GENERATOR
: saturated flow
: HJ. Morel-Seytoux, CJ. Daly, G. Peters
: Engineering Research Center, Colorado State University
: IGWMC
: DELTA

: saturated flow
: H.J. Morel-Seytoux, C. Rodriquez, C. Daly, T. Illangasekare, Peters
: Colorado State University Engineering Research Center
: IGWMC
D-6

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36.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

37.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

38.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

39.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

40.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

41.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

42.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: DELTIS
: Deltis-Stream Aquifer Discrete Kernel Generator
: saturated flow
: H.J. Morel-Seytoux, T. Illangasekare
: Engineering Research Center, Colorado State University
: IGWMC
 DEWATER

 saturated flow
 B. Sagar
 Analytic and Computational Research, Inc.
 IGWMC
 DFT/C-1D

: saturated flow
 C.S. Desai
 Dept. of Civil Engineering University of Arizona
 IGWMC
: DISIFLAG

: saturated flow
: O. Berney
: Land & Water Dev. Div. Food & Agriculture Organization
: IGWMC
; DISPEQ

: solute transport
: H. Fluhler, W.A. Jury
 Swiss Federal Inst. of Research
: IGWMC
: DOSTOMAN

: solute transport
: King, Wilhite, Root Jr., Fauth, Routt, Emslie, Beckmeyer
: E.I. Dupont de Nemours & Corp. Savannah River Lab.
; IGWMC
; DRAINMOD

: estimate position of water table
: W.R. Skaggs
: Dept. of Biological and Agricultural Eng. North Carolina State Univ
: IGWMC
D-7

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43.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

44.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

45.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

46.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

47.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

48.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

49.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
:DSTRAM

: solute transport
: P.S. Huyakorn
; HydroGeoLogic, Inc.
: IGWMC
: ECPL 704-F3-RO-011

: saturated flow
; F.T. Tracy
: US. Army Engineer Waterways Automatic Data Processing Division
: IGWMC
:ECPL723-G2-L2440

: saturated flow
: R.L. Cooley, J. Peters
: Hydrologic Engineering Center, U.S. Army Corps of Engineers
: IGWMC
: EP21-GWTHERM

: heat transport
: A.K. Runchal, J. Treger, G. Segal
: Dames and Moore Advanced Technology Group
: IGWMC
: EQ3NR/6

: hydrochemical
: Wolary, T. J.
: Lawrence Livermore National Laboratory
: IGWMC
: EQUILIB

: hydrochemical
: Morrey, J. R., Shannon, D. W.
: Electric Power Research Institute
: IGWMC
:FE3DGW

: saturated flow
; S.K. Gupta, C.R. Cole, F.W. Bond
: Water & Land Resources Division Battelle Pacific NW Lab.
: IGWMC
D-8

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50.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

51.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

52.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

53.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

54.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

55.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

56.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
: FEATSMF

: variably saturated flow
 J.L. Neiber
: Dept. of Agriculture Engineering, Cornell University
:FEM301

: fractured rock
: Kiraly, L.
; National Cooperative for Storage of Radioactive Waste-NAGRA
: IGWMC
;FEMA

: solute transport
; G.T. Yeh, D.D. Huff
: Environmental Sci. Div. Oak Ridge National Lab.
: IGWMC
; FEMSAT

: saturated flow
; P.J.T. van Bakel
; Institute for Land and Water Management Research
; IGWMC
;FEMTRAN

: solute transport
: M.J. Martinez
: Fluid Mechanics & Heat Transfer Div. Sandia National lab.
: IGWMC
: FEMWASTE

: solute transport
: G.T. Yeh, D.S. Ward
: Environmental Sciences Division Oak Ridge National Lab
: IGWMC
: FEMWATER

: variably saturated flow
: G.T. Yeh, D.S. Ward
: Environmental Sciences Division Oak Ridge National Lab
: IGWMC
D-9

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57.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

58.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

59.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

60.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

61.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

62.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

63.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
; FESOSPF
: FINITE ELEMENT SOLUTION OF STEADY-STATE POTENTIAL FLOW PROBLEMS
: saturated flow
: R.L. Cooley, J. Peters
: Hydrologic Engineering Center U.S. Army Corps of Engineers
: IGWMC
:FEWA

: saturated flow
; G.T. Yeh, D.D. Huff
: Environmental Sciences Division Oak Ridge National Lab
: IGWMC
: FIELD-2D

: saturated flow
: C.S. Desai
: Department of Civil Engineering University of Arizona
; IGWMC  .
: FLAMINGO

: solute transport
: P.S. Huyakorn
: GeoTrans, Inc.
: IGWMC
;FLO

: variably saturated flow
: A. Vanderberg
: National Hydrology Research Institute Inland Waters Directorate
: IGWMC
:FLOP

: saturated flow
: C. van den Akker
: National Institute for Water Supply
: IGWMC
:FLOTRA

: heat transport
 Sagar, B.
: Analytic & Computational Research, Inc.
: IGWMC
D-10

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64.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

65.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

66.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

67.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

68.
Model Name
Full Name
Purpose
Developer
Affiliation.
Source

69.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

70.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
; FLOWVEC

; variably saturated flow
: R-L U, K.G. Eggert, K. Zachmann
; Simmons, Li & Associates, Inc.
: IGWMC
: FLUMP

: variably saturated flow
: T.N. Narasirnhan, S.P. Neuman
; Earth Sciences Division Lawerence Berkeley Laboratory Univ. Cailif.
: IGWMC
: FRACFLOW

: fractured rock
: Sagar, B.
: Analytic & Computational Research, Inc.
: IGWMC
: FRACPORT

: fractured rock
: Deangelis, D.L., Yeh, G.T., Huff, D.D.
: Oak Ridge National Laboratory
: IGWMC
 FRACSL

 fractured rock
 Miller, J. D.
 Idaho National Engineering Lab.
 IGWMC
: FRACSOL

: fractured rock
: Pickens, J. F.
: INTERA Technologies, Inc.
: IGWMC
iFRACT

: fractured rock
: Pickens, J. F.
: INTERA Technologies, Inc.
: INTERA Technologies, Inc.
D-11

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71.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

72.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

73.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

74.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

75.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

76.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

77.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
;FRACTEST
i
: fractured rock
; Karasaki, K.
: Lawrence Berkeley Lab., Univ. of California
: IGWMC
; FREESURF-1
i

: saturated flow
; S.P. Neuman, P.A. Witherspoon
: Department of Hydrology and Water Resources, University of Arizona
: IGWMC
: FRONT
i
: saturated flow
: C van den Akker
: National Institute for Water Supply
; IGWMC
 FRONTTRACK

 solute transport
 S.P. Garabedian, L.F. Konikow
 Water Resources Division U.S. Geological Survey
 IGWMC
iGAFETTA

: heat transport
: G.F. Finder, P.E. Kinnmark, C.I. Voss
: Dept. of Civil Engineering
: IGWMC
: GASOLINE

: multiphase flow
: Baehr, A. L.
: U.S.G.S. Water Resources Div., National Center
: IGWMC
:GEOCHEM

: hydrochemical
: Sposito, G., Mattigod, S. V.
: Department of Soil and Environmental Sciences
: IGWMC
D-12

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78.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

79.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

80.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

81.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

82.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

83.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

84.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: GEOFLOW

: solute transport
: S. Haji-Djafari, T.C. Wells
: D'Appolonia Waste Mngmt. Services, Inc.
: IGWMC
:GEOTHER

: multiphase flow
: Faust, C. R., Mercer, J. W.
: Office of Nuclear Waste Isolation, Battelle
: IGWMC
:GETOUT

: solute transport
: Burkholder, Cloninger, Dernier, Jansen, Liddell, Washburn
: Nat'l Energy Software Center Argonne Natl. Laboratory
: IGWMC
:GGCP
: Colder Groundwater Computer Package
: solute transport
: I. Miller, J. Marlon-Lambert
: Colder Associates
: IGWMC
:GM5

: saturated flow
: J.A. Liggett
: School of Civil and Environmental Engineering Cornell University
: IGWMC
: GREASE-2

: heat transport
: Huyakorn, P.S.
: GeoTrans, Inc.
: IGWMC
 GROMAGE

 saturated flow
 B.H. Gilding, J.W. Wesseling
 Delft Hydraulics Lab
 IGWMC
D-13

-------
85.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

86.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

87.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

88.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

89.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

90.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

91.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
iGROMULA
»
*
: saturated flow
: A.P.M. Broks, D. Dijkstra, J.W. Wesseling
: Delft Hydraulics Lab
; IGWMC
: GROWKWA

: solute transport
: J.W. Wesseling
: Delft Hydraulics Lab.
: IGWMC
: GRWATER

: variably saturated flow
: D.K. Sunada
: Dept. of Civil Eng. Colorado State University
: IGWMC
:GS2

: solute transport
: L.A. Davis, G. Segol
: Water, Waste and Land, Inc.
: IGWMC
;GS3
i
*
: solute transport
: L.A. Davis, G. Segol
; Water, Waste, and Land, Inc.
: IGWMC
:GW1

: calculation of heads for dewatering
: B. Boehm
: Abteilung Wasserwirtschaft Rheinbraun
: IGWMC
; GWEFLOW

: saturated flow
: P.K.M. van der Heijde
: Int'l Ground Water Modeling Ctr. Holcomb Research Institute
: IGWMC
D-14

-------
92.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

93.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

94.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

95.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

96.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

97.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

98.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
; GWMD-3
: GWMD3-APPROPRIATION MODEL
: saturated flow
: D.G. Jorgensen, H. Grubb, C.H. Bakerjr., G.E. Hilmes, E.D. Jenkins
: U.S. Geological Survey Water Research Dept. University of Kansas
: IGWMC
: GWPATH

: saturated flow
: J.M. Shafer
: Illinois State Water Survey Ground Water Section
: IGWMC
: GWSIM

: saturated flow
: T.R. Knowles
: Texas Department of Water Resources
: IGWMC
: GWSIM-2

: solute transport
: T.R. Knoles
: Texas Dept. of Water Res.
: IGWMC
: GWUSER

: saturated flow
: C.R. Kolterman
: Water Resources Center Desert Research Inst. Univ. of Nevada System
: IGWMC
 HOTWTR

 heat transport
 J.E. Read
 U.S. Geological Survey
 IGWMC
: HSSWDS

: variably saturated flow
: E.R. Perrier, A.C. Gibson
; Solid & Hazardous Waste Research Div. Municipal Env. Research Lab.
: IGWMC
D-15

-------
99.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

100.
Model Name
Full Name
MODEL
Purpose
Developer
Affiliation
Source

101.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

102.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

103.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

104.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

105.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
;HST3D

: heat transport
; K.L. Kipp
: U.S. Geological Survey and IGWMC
; IGWMC
; IASIPMAM
: ITERNATIVE ALGOITHM SOLVING INVERSE PROBLEM MULTICELL AQUIFER

: saturated flow
: Y. Bachmat, A. Dax
: Hydrological Service of Israel
: IGWMC
:IDPNGM
: I.D.P.N.G.M.
: saturated flow
: V. Guvanasen
: Dept. of Civil & System Engineer. James Cook Univ. North Queenlands
: IGWMC
:INFGR

: variably saturated flow
: P.M. Craig, E.G. Davis
 Environmental Science Division Oak Ridge Nat'l Laboratory
: IGWMC
: INFIL

: variably saturated flow
: M. Vauclin
: Institute De Mecanique De Grenoble
; IGWMC
: INFIL

: variably saturated flow
: A.I. El-Kadi
: IGWMC, Holcomb Research Institute
: IGWMC
: INTERFACE
i
: multiphase flow
: Page, R. H.
: Water Resources Program, Princeton University
: IGWMC
D-16

-------
106.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

107.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

108.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

109.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

110.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

111.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

112.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: INVERS

: saturated flow
: W.I.M. Elderhorst
: Institute for Applied Geosciences
: IGWMC
: IONMIG

: solute transport
: A.J. Russon
: Fluid Mechanics & Heat Transfer Division Sandia National Lab.
: IGWMC
: ISL-50

: solute transport
: R.D. Schmidt
: U.S. Dept. of the Interior Bureau of Mines
: IGWMC
: ISOQUAD

; saturated flow
: G.F. Pinder, E.O. Frind
; Department of Civil Engineering Princeton University
: IGWMC
: ISOQUAD-2

: solute transport
: G.F. Pinder
: Dept. of Civil Eng. Princeton University
: IGWMC
:KRGW
i

: saturated flow
: H.N. Tyson
: Food and Agriculture Organization, United Nations
: IGWMC
 LAFTID

 saturated flow
 I. Herrera, J.P. Hennart, R. Yates
 Intituto De Geofisica Ciudad Universitaria
 IGWMC
D-17

-------
113.
Model Name
Full Name
Purpose
Developer
Affiliation
.Source

114.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

115.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

116.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

117.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

118.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

119.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
iLANDFIL
i
: variably saturated flow
: G.P. Korfiatis
: Civil and Environmental Engineering Rutgers University
; IGWMC
: LAS
: LEAKY AQUIFER SIMULATION
: saturated flow
: T. Maddock
: Water Resources Dev. & Mgt. Svc. Land & Water Dev.Org. Food & Agric
: IGWMC
 MAGNUM-2D

 heat transport
: England, R.L., Mine, M.W., Ebblad, K.J., Bace, R.G.
: Rockwell Hanford Operations
; IGWMC
:MAQWF

: saturated flow
; D.N. Contractor, S.M.A. El Didy, A.S. Ansary
: Department of Civil Engineering University of Arizona
: IGWMC
; MAQWQ

: solute transport
: D.N. Contractor, S.M.A. El Didy, A.S. Ansary
; Dept. of Civil Sc Mechanical Engineering University of Arizona
: IGWMC
 MARIAH

 heat transport
 D.K. Gartling
 Sandia Nat'l Labs
 IGWMC
:MATTUM

: heat transport
: Yeh, G. T. & Luxmoore, R. J.
: Environmental Sci. Div., Oak Ridge National Lab
: IGWMC
D-18

-------
120.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

121.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

122.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

123.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

124.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

125.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

126.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: MINEQL2
»
; hydrochemical
: Westall, J. C, Zachary, J. L., Morel, F. M. M.
: Dept. of Civil Engineering, Mass. Institute of Technology
: IGWMC
;MMT-1D

: heat transport
; F.E. Kaszeta, C.S. Simmons, C.R. Cole
; Battelle Pacific NW Labs
: IGWMC
 MMT-DPRW

 heat transport
 S.W. Ahistrom, H.P. Foote, R.J. Serne
 Battelle Pacific NW Labs
 IGWMC
: MODFLOW

: saturated flow
: M.G. McDonald, A.W. Harbaugh
; Ground Water Branch, WRD U.S. Geological Survey
; IGWMC
: MOTGRO

: multiphase flow
: Van Der Veer, P.
: Rijkswaterstaat, Data Processing Division
: IGWMC
: MOTIF

: fractured rock
: Guvanasen, V.
: AECL Whiteshell Nuclear Research Establishment
: IGWMC
iMULKOM

; multiphase flow
: Pruess, K.
: Lawrence Berkeley Lab
; IGWMC
D-19

-------
127.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

128.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

129.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

130.
Model Najne
Full Name
Purpose
Developer
Affiliation
Source

131.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

132.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

133.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
iMUSHRM

: multiphase flow
; Pritchett, J. W.
: Systems, Science and Software
: IGWMC
:MUST

: variably saturated flow
: P.J.M. Delaat
: International Inst. for Hydraulic and Environm. Engineering
iIGWMC
iNETFLOW

: fractured rock
; Pahwa, S. B., Rama Rao, B. S.
; Office of Nuclear Waste Isolation, Battelle
: IGWMC
iNTTROSIM

: solute transport
: P.S.C. Rao
: Soil Science Dept. University of Florida
: IGWMC
iNLRGFM
: NON-LINEAR REGRESSION GROUNDWATER FLOW MODEL
: saturated flow
: R.L. Cooley, R.L. Naff
: U.S. Geological Survey Water Resources Division
; IGWMC
: NMFD-3D
 N.M.F.D.3D
: saturated flow
 D.R. Posson, G.A. Hearne, J.V. Tracy, P.F. Frenzel
; U.S. Geological Survey
: IGWMC
: NMODEL

: solute transport
: H.M. Selim, J.M. Davidson
: Louisana Agricultural Experiment Station Louisana State University
; IGWMC
D-20

-------
134.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

135.
Model Name
Full Name
Purpose
Developer
Affiliation
Source  •

136.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

137.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

138!
Model Name
Full Name
Purpose
Developer
Affiliation
Source

139.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

140.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: ONE STEP

: variably saturated flow
: J.B. Kool, J.C. Parker, M.Th. van Genuchten
: 245 Smyth hall Va. Polytechnic Inst.
: IGWMC
:ONE-D

: solute transport
: M.Th. van Genuchten, W.J. Alves
; IGWMC Holcomb Research Institute
: IGWMC
: PATHS

: solute transport
: R.W. Nelson
: Battelle Pacific NW Labs
: IGWMC
:PE
: PARAMETER ESTIMATION PROGRAM
: saturated flow
: J.V. Tracy
: U.S. Geological Survey Water Resources Dept. National Center
: IGWMC
:PEP

: saturated flow
: D.E. Evenson
: CDM Water Resources Engineers
: IGWMC
: PHREEQE

: hydrochemical
: Parkhurst, D. L., Thorstenson, D. C, Plummer, L. N.
: U.S. Geological Survey, Wter Resources Division
; IGWMC
: PISTON

: solute transport
: H. Fluhler, W.A. Jury
; Swiss Federal Inst. of Research
: IGWMC
D-21

-------
141.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

142.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

143.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

144.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

145.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

146.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

147.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: PLASM

: saturated flow
: T.A. Prickett, CG. Lonnquist
: Consulting Water Resource Engineers
: IGWMC
:PUN

: saturated flow
: A. Levassor
: Centre D'lnformatique Geologique Ecol Des Mines De Paris
: IGWMC
; PLUME-2D

: solute transport
: P.K.M. van der Heijde
: IGWMC Holcomb Research Institute
: IGWMC
; PORFLOW

: heat transport
: Kline, N. W., Runchal, A. K., Baca, R. G.
: Energy Systems Group, Rockwell International
; IGWMC
; PORFLOW H

: solute transport
: A.K. Runchal
: Analytic & Computational Research, Inc.
: IGWMC
iPORFREEZE
»
: heat transport
: Runchal, A. K.
: Analytic & Computational Research, Inc.
: IGWMC
: PROTOCOL

: hydrochemical
; Pickrell, G., Jackson, D. D.
; Lawrence Livermore National Laboratory
: IGWMC
D-22

-------
148.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

149.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

150.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

151.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

152.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

153.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

154.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
:PT
: heat transport
: Bodvarsson, A. S.
: Lawrence Berkeley Lab., University of California
: IGWMC
:PT/CCC

: heat transport
: M.J. Lippman, T.N. Naraimhan, D.C. Mangold, G.S. Bodvarsson
: Nat'l Energy Software Center Argonne Nat'l Lab.
: IGWMC
:PUMPTEST

: saturated flow
: M.S. Beljin
: IGWMC, Holcomb Research Institute
: IGWMC
: QTDMA
: Quasi Three-Dimensional Multi-Aquifer Model
: saturated flow
: J.B. Weeks
: U.S. Geological Survey Water Resources Division
: IGWMC
 RADFLOW

 saturated flow
 K.S. Rathod, K.R. Rushton
 Int'l Ground Water Modeling Center Holcomb Research Institute
 IGWMC
: RANDOM WALK

; solute transport
: T.A. Prickett, T.G. Naymik, C.G. Lonnquist
: 111. State Water Survey
: IGWMC
: REDEQL-UMD

: hydrochemical
: Harriss, D.K., Ingle, S.E., Taylor, D.K., Magnuson, V.R.
: Dept. of Chemistry, University of Minnesota
: IGWMC
D-23

-------
155.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

156.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

157.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

158.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

159.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

160.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

161.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: REDEQL.EPA

: hydrochemical
: Ingle, S.E., Schuldt, M.D., Schults, D.W.
: Hatfield Marine Sci. Cntr., U.S. EPA
: IGWMC
:RESTOR

: solute transport
; J.W. Warner
: Civil Engineering Dept.  Colorado State Univ.
: IGWMC
:RTTZ

: solute transport
: D.L. Nofziger, J.R. Williams. T.E. Short
; Robert S. Karr Environmental Research Lab U.S. EPA
: IGWMC
: ROCMAS-H

: fractured rock
: Noorishad, J., Witherspoon, P. A.
: Lawrence Berkeley Laboratory, Univ. of California
: IGWMC
: ROCMAS-HM

: fractured rock
: Noorishad, J., Ayatollahi, M. S., Witherspoon, P. A.
: Lawrence Berkeley Laboratory, Univ. of California
; IGWMC
: ROCMAS-HS
i
: fractured rock
: Noorishad, J., Mcnran, M.
; Lawrence Berkeley Laboratory, Univ. of California
: IGWMC
: ROCMAS-HW

: saturated flow
; J. Noorishad, M.S. Ayatollahi, P.A. Witherspoon
: Earth Sciences Division Lawrence Berkeley Lab. Univ. of California
: IGWMC
D-24

-------
162.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

163.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

164.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

165.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

166.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

167.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

168.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: ROCMAS-THM

: fractured rock
: Noorishad, J., Witherspoon, P. A.
: Lawrence Berkeley Lab., Univ. of California
: IGWMC
:SANGRE

: heat transport
: Anderson, CA.
: Los Alamos Nat'l. Lab.
: IGWMC
; SATRA-CHEM

: solute transport
: P.M. Lewis, C.I. Voss, J. Rubin
: U.S. Geological Survey National Center
: IGWMC
: SATURN-2

: solute transport
: P. Huyakom
: GeoTrans, Inc.
: IGWMC
: SBIR

; solute transport
: R.M. Li
: Simous, Li & Assoc., Inc.
: IGWMC
: SCHAFF

: heat transport
: M.L. Sorey, M.J. Lippman
: Nat'l Energy Software Center Argonne Nat'l Lab
: IGWMC
: SEAWTR

: multiphase flow
: Allayla, R. I.
: Civil Eng. Dept, Colorado State Univ.
: IGWMC
D-25

-------
169.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

170.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

171.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

172.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

173.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

174.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

175.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
; SEEP(VM)-3D

 saturated flow
 C.S. Desai
: Department of Civil Engineering University of Arizona
:IGWMC
: SEEP2(VM)-2D

: saturated flow
: C.S. Desai
: Department of Civil Engineering University of Arizona
iIGWMC
;SEEPV

: variably saturated flow
: L.A. Davis
: Water, Waste and Land, Inc.
: IGWMC
:SEFTRAN

: heat transport
: Huyakorn, P.S.
: GeoTrans, Inc.
: IGWMC
; SESOIL

: solute transport
: M. Bonazountas, J.M. Wagner
: Office of Toxic Substances U.S. EPA
: IGWMC
:SGMP
: S.G.M.P.
: saturated flow
: J. Boonstra
: Inter'l Inst. for Land Reclamation and Improvement
: IGWMC
: SHAFT-79

: heat transport
: K. Pruess, R.C. Schroeder
: Nat'l Energy Software Center Argonne Nat'l Lab
: IGWMC
D-26

-------
176.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

177.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

178.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

179.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

180.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

181.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

182.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: SHALT

: heat transport
: J.F. Pickens, G.E. Grisak
: INTERA Technologies, Inc.
: IGWMC
: SICK-100

: saturated flow
: G. Schmid
; Ruhr-University Bochum Institute F. Konst. Ingenieubau AGIV
: IGWMC
;SOIL

: variably saturated flow
: A.I. El-Kadi
: Int'l Ground Water Modeling Center Holcomb Research Institute
; IGWMC
; SOILMOP

: variably saturated flow
: D.L. Ross, HJ. Morel-Seytoux
; Dept. of Civil Eng. Colorado State University
: IGWMC
: SOLMNEQ

: hydrochemical
: Kharaka, Y. K., Barnes, I.
 U.S. Geological Survey, MS/427
: IGWMC
: SOLMNQ

: hydrochemical
: Goodwin, B. W., Munday, M.
: Atomic Energy of Canada Ltd., Whiteshell Nuc. Res. Establishment
: IGWMC
: SOLUTE

: solute transport
: M.S. Beljin
: IGWMC Holcomb Research Institute
: IGWMC
D-27.

-------
183.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

184.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

185.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

186.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

187.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

188.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

189.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
;SOMOF

: variably saturated flow
: J.W. Wesseling
: Delft Hydraulics Laboratory
: IGWMC
 SOTRAN

 solute transport
 I.L. Nwaogazie
 I.L. Nwaogazie Dept. of Civil Eng. Univ. of Port Harcourt
 IGWMC
: SPLASHWATR

: heat transport
: Milly, P.C.D.
: Massachusetts Inst. of Technology, Dept. of Civil Eng.
: IGWMC
:ST-2D

; saturated flow
; A.I. El-Kadi
; Int'l Ground Water Modeling Ctr. Holcomb Research Inst. Butler Univ
: IGWMC
 STAFAN-2

 fractured rock
 Huyakorn, P.S.
 Office of Nuclear Waste Isoliation, Battelle
 IGWMC
: STAFF-2D

: fractured rock
: Huyakorn, P. S.
: HydroGeoLogic, Inc.
: IGWMC
iSTFLO

: saturated flow
: C.R. Faust, T. Chan, B5. Ramada, B.M. Thompson
: Performance Assest. Dept.of Nucl. Water Isolation Battelle Prj. Mgt
: IGWMC
D-28

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190.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

191.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

192.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

193.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

194.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

195.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

196.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
; STRESEEP-2D

: saturated flow
: C.S. Desai
: Department of Civil Engineering  University of Arizona
; IGWMC
: SUGARWAT

: fractured rock
: Holditch, S. A., and Associates
: U.S. Dept. of Energy, Morgantown Energy Technology Center
: IGWMC
:SUTRA

: heat transport
; Voss, C. I.
: U.S. Geological Survey
: IGWMC
: SWANFLOW

: multiphase flow
: Faust, C. R., Rumbaugh, J. D.
: GeoTrans, Inc.
: IGWMC
; SWATRE

: variably saturated flow
: R.A. Feddes
; Inst. for Land and Water Management Research
; IGWMC
: SWENT

: heat transport
: INTERA, Inc.
: INTERA Technologies, Inc.
: IGWMC
 SWIFT

 heat transport
 Dillion, R.T., Cranwell, R.M., Lantz, R. B., Pahwa, S.B., Reeves M.
 Argonne National Lab.
 IGWMC
D-29

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197.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

198.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

199.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

200.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

201.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

202.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

203.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
; SWIFT

: multiphase flow
 Verruijt, A., Can, J. B. S.
: Technical University of Delft, Department of Civil Engineering
: IGWMC
: SWIGS-2D

: multiphase flow
: Contractor, D. N.
: Water and Energy Research Inst. of the Western Pacific, U. of Guam
: IGWMC
:SWIM

: multiphase flow
: Sada Costa, A. A. G., Wilson, J. L.
: Lab. for Water Resources and Hydrodynamics, MIT
; IGWMC
: SWIPR

: solute transport
: INTERA Environmental Consult., Inc.
: U.S. Geological Survey Denver Federal Center
: IGWMC
: SWSOR
»
: multiphase flow
: Mercer, J. W., Faust, C R.
: GeoTrans, Inc.
: IGWMC
 SYLENS

 saturated flow
 H.M. Haitjema, O.D.L. Strack
 School of Public & Environmental Affairs  Indiana University
 IGWMC
: TERZAGI

: saturated flow
: T.R. Narasimhan
: National Energy Software Center (NESC), Argonne National Laboratory
: IGWMC
D-30

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204.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

205.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

206.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

207.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

208.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

209.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

210.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
:TETRA

: saturated flow
: L.A. Abriola, G.F. Finder
: Int'l Ground Water Modeling Center Holcomb Research Institute
: IGWMC
: TEXASHEAT

: heat transport
: Grubaugh, E. K., Reddell, D. L.
 Texas Water Res. Inst, Texas A&M Univ.
 IGWMC
iTGUESS

: saturated flow
: K.R. Bradbury, E.R. Rothschild
; Int'l Ground Water Modeling Center Holcomb Research Institute
: IGWMC
: THCVFIT

: saturated flow
: P.K.M. van der Heijde
; Int'l Ground Water Modeling Center Holcomb Research Institute
: IGWMC
: THWELLS

: saturated flow
: P.K.M. van der Heijde
: IGWMC, Holcomb Research Institute
: IGWMC
:TIMLAG

: saturated flow
: D.B. Thompson
: IGWMC, Holcomb Research Institute
: IGWMC
: TOFEM-N

: saturated flow
: T.N. Olsthoorn
: Nansenlael W.
: IGWMC
D-31

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211.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

212.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

213.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

214.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

215.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

216.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

217.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: TOUGH
t
: fractured rock
: Pruess, K., Tsang, Y. W., Wang, J. S. Y.
: Lawrence Berkeley Laboratory, University of California
: IGWMC
; TRACR-3D

: fractured rock
; Travis, B. J.
: Los Alamos National Laboratory
; IGWMC
: TRAFRAP-WT

: fractured rock
: Huyakorn, P. S., White, H. O., Wadsworth, T. D.
: Holcomb Research Institute
: IGWMC
 TRANQL

; solute transport
; G.A. Cederberg, R.L. Street, J.O. Leckie
: Los Alamos National Lab.
; IGWMC
: TRANS

: heat transport
: W.R. Walker, J.D. Sabey
: Water Resources Research Ctr. Virginia Polytechnic Institute
: IGWMC
 TRIGAT-HSI

 saturated flow
 P. Prudhomme, J.L. Henry, F. Biesel
 Laboratoire Central D'Hydraulic De France
 IGWMC
;TRIPM

: solute transport
: A.B. Gureghian
: ONWI, Battelle Memorial Institute
: IGWMC
D-32

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218.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

219.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

220.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

221.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

222.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

223.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

224.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
: TRUCHN/ZONE

: fractured rock
: Resmuson, A., Neretnieks, I.
: Royal Institute of Technology
: IGWMC
; TRUMP

: fractured rock
: Edwards, A.L., Rasmuson, A., Neretnieks, I., Narasimhan, T.N.
: Royal Inst. of Technology
: IGWMC
 TRUST

: variably saturated flow
 T.N. Narasimhan
: Water and Land Resources Division Battelle Pacific NW Lab.
: IGWMC
: TSSLEAK

: saturated flow
: P.M. Cobb, C.D. Mcelwee, M.A. Butt
: Kansas Geological Survey, University of Kansas
: IGWMC
: TSSLEAK

: saturated flow
: P.K.M. van der Heijde
; IGWMC Holcomb Research Institute
: IGWMC
: UNSAT-1

; variably saturated flow
: M. Th. van Genuchten
: U.S. Salinity Lab U.S. Dept. of Agriculture
; IGWMC
: UNSAT-1D

: variably saturated flow
: S.K. Gupta, C.S. Simmons
: Battelle Pacific NW Labs
: IGWMC
D-33

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225.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

226.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

227.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

228.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

229.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

230.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

231.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
; UNSAT-2
i

: variably saturated flow
: S.P. Neuman
: Dept. of Hydrology and Water Resources Univ. of Arizona
: IGWMC
: UNSAT-H

: variably saturated flow
: MJ. Payer, G.W. Gee
: Battelle Pacific Northwest Lab
: IGWMC
: USGS-2D-FLOW

: saturated flow
: P.C. Trescott, G J. Finder, S.P. Larson
: VS. Geological Survey Branch of Groundwater
: IGWMC
: USGS-2D-TRANSPORT/MOC

: solute transport
: L.F. Konilow, J.D. Bredehoeft
: U.S. Geological Survey
: IGWMC
: USGS-3D-FLOW
i
: saturated flow
: P.C Trescott, S.P. Larson
: US. Geological Survey Branch of Groundwater
: IGWMC
: UWIS-2D-TRANSPORT

: heat transport
: C.B. Andrews
: Woodward-Clyde Cnslt.
: IGWMC
:VADOSE
»
: heat transport
: Sagar, B.
; Analytic & Computational Research, Inc.
: IGWMC
D-34

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232.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

233.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

234.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

235.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

236.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

237.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

238.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: VAM-2D

: solute transport
: P.S. Huyakorn
: HydroGeoLogic, Inc.
: IGWMC
: VAM-3D

: solute transport
: P.S. Huyakorn
: HydroGeoLogic, Inc.
: IGWMC
: VARQ

; saturated flow
: M.A. Butt, C.D. McElwee
: Int'l Ground Water Modeling Center Holcomb Research Institute
: IGWMC
:VDM
: VARIABLE DENSITY MODEL
: saturated flow
: L.K. Kuiper
: U.S. Geological Survey
: IGWMC
: VS-2D

: variably saturated flow
: E.G. Lappala, R.W. Healy, E.P. Weeks
: U.S. Geological Survey Denver Federal Center
: IGWMC
 VTT
: saturated flow
: A.E. Reisenaurer, C.R. Cole
: Water & Land Resources Division  Battelle Pacific NW Lab.
: IGWMC
: VTTSS-2

: saturated flow
: A.E. Reisenauer, C.R. Cole
: Water & Land Resources Division  Battelle Pacific NW Lab.
; IGWMC
0-35

-------
239.
Model Name
Full Name
Putpose
Developer
Affiliation
Source

240.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

241.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

242.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

243.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

244.
Model Name
Full Name
Purpose
Developer
Affiliation
Source

245.
Model Name
Full Name
Purpose
Developer
Affiliation
Source
: VTTSS-3

: saturated flow
; A.E. Reisenauer, C.R. Cole
 Water & Land Resources Division Battelle Pacific NW Lab.
: IGWMC
: WALTON-35

: solute transport
: W.C. Walton
: IGWMC Holcomb Research Institute
: IGWMC
; WASTE

: solute transport
: B. Ross, CM. Koplik
: Analytical Sciences Corp. Energy & Environment Div.
; IGWMC
: WATEQ-2

: hydrochemical
; Ball, J. W., Jenne, E. A., Nordstrom, D. K.
; U.S. Geological Survey
: IGWMC
: WATEQ-3
>
: hydrochemical
: Ball, J. W., Jenne, E. A., Cantrell, M. W.
: US. Geological Survey, MS/21
: IGWMC
: WATEQF
i
: hydrochemical
: Plummer, L. M., Jones, B. F., Truesdell, A. H.
: U.S. Geological Survey, Water Resources Division
: IGWMC
  : WATERFLO

  : variably saturated flow
  : D.L. Nofziger
  : Institute of Food & Agriculture Sciences University of Florida
  : IGWMC
D-36

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Exposure Assessment Models
1.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

2.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

3.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

4.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

5.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

6.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

7.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
: DYNHYD-4
: Dynamic Estuary Model
: flow, transport, and degradation in rivers and estuaries
; Feigner, K.D., Harris, H.S.
: Federal Water Quality Administration, U.S. Dept. of Interior
: David Disney, CEAM
:DYNTOX
: Dynamic Toxicity Model
: predict concentrations of contaminants in surface waters

: Limno-Tech
: David Disney, CEAM
:EXAMS-2
: Exposure Analysis Modeling System, Version 2.92
: predict concentrations of contaminants in surface water
: Burns, L.A., Cline, D.M., Lassiter, R.R.
: U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
:FGETS
: Food and Gill Exchange of Toxic Substances
: predict bioaccumulation of nonpolar organic pollutants in fish
 David Disney, CEAM
:GEMS
: Graphical Exposure Modeling System
: air, soil, and groundwater analysis

: ERL-Athens, GA
: Russell Kinerson, EPA OTS, (202) 382-3928
:HSPF
: Hydrological Simulation Program - FORTRAN
: predict contaminant concentrations in runoff, surface, ground water

• U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
: MINTEQA-2
: Equilibrium Metal Speciation Model
: predict concentrations of contaminants in surface and ground waters
: Felmy, A.R., Girvin, D.C., and Jenne, E.A.
: U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
D-37

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8.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

9.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

10.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

11.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

12.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

13.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
:PRZM
: Pesticide Root Zone Model
: predict concentrations of contaminants in ground waters
: Carsel, R.F., Smith, C.N., Mulkey, L.A., Dean, J.D., Jowise, P.
: U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
: SARAH-2
: Surface Water Assessment Model
: predict concentrations of contaminants in surface waters
: Ambrose, R.B. and Vandergrift, S.B.
: U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
: SHAPE
: Simulation of Human Activity and Pollutant Exposure
: model distribution of population exposures to carbon monoxide
: Ott, Wayne
: U.S. EPA, ORD
: Ott, Wayne, U.S. EPA, ORD
:SWMM-4
: Storm Water Management Model
: nonpoint source runoff from urban areas
: Huber, W.C., Heaney, J.P., Nix, S.J., Dickinson, R.E., Polmann, D.
: U.S. EPA, ERL-Cincinnati, OH
: Tom Barnwell, U.S. EPA, ERL, Athens, GA
: WASP-4
: Water Analysis Simulation Programs
: predict concentrations of contaminants in surface waters

: U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
:WQA
: Water Quality Assessment
: predict cncntrtions of cntmnts in runoff, surface, and ground water

: U.S. EPA, ERL-Athens, GA
: David Disney, CEAM
D-38

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Air Dispersion Models
1.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

2.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

3.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

4.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

5.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

6.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

7.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
: APRAC-3

: computes hourly average carbon monoxide concentrations
: Simmon P.B., Patterson, R.M., Ludwig, F.L., Jones, L.B.
:SRI
: AREAL, NTIS
:BLP
: Buoyant Line and Point Source Dispersion Model
: plume rise and downwash effects from stationary line sources
: Schulman, L. L., and Scire, J. S.
: Environmental Research and Technology, Inc.
: AREAL, NTIS
: CALINE-3
: California Line Source Dispersion Model
: predict carbon monoxide concentrations near highways
: Benson, P. E.
: California Department of Transportation
: AREAL, NTIS
: CDM-2
: Climatological Dispersion Model-Version 2.0
: predict pollutant concentrations in rural or urban settings
: Irwin, J. S., T. Chico, and J. Catalano
: U.S. EPA, ASRL
: AREAL, NTIS
: CHEMDAT6

: estimate volatile organic compound emissions from TSDF processes

:OAQPS
:OAQPS


: COMPLEX-1

: estimate concentrations of inert pollutants

; U.S. EPA, ASRL
 AREAL, NTIS
: CRSTER
: Single Source (CRSTER) Model
: calculate concentrations from point source at polar coord, receptor
: Monitoring and Data Analysis Division
: U.S. EPA, OAQPS
: AREAL, NTIS
D-39

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8.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

9.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

10.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

11.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

12.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

13.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

14.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
: HIWAY-2
: Highway Air Pollution Model
: estimate concentration of non-reactive pollutants downwind of roads
: Petersen, W.B.
: US. EPA, ASRL
: AREAL, NTIS
: INPUFF
: Multiple Source Gaussian Puff Dispersion Algorithm
: estimate pollutant concentrations downwind of incinerator ships
: Petersen, W.B., and Lavdas, L.G.
: US. EPA, ASRL
: AREAL, NTIS
:ISC
: Industrial Source Complex
: assess pollutant concentrations associated w\ an industrial source
: Environmental Protection Agency
: US. EPA, OAQPS
: AREAL, NTIS
:LONGZ

: calculate long term concentrations at receptors
: Bjorklund, J.R., Bowers, J.F.
: H.E. Cramer Co.
: AREAL, NTIS
: MESOPUFF-2
: Mesoscale PUFF Model
: model the transport, diffusion and removal of air pollutants
: Scire, J.S., Lurmann, F.W., Bass, A., and Hanna, S.R.
: ERT, Inc.
: AREAL, NTIS
iMPTDS
: Multiple Point Source Model With Deposition
: estimate concentrations for inert pollutants
: Rao, K.S., Satterfield,  L.
:ONRL
: AREAL, NTIS
:MPTER
: Multiple Point Gaussian Dispersion Algorithm with Terrain Adjustmen
: estimate concentrations for inert pollutants
: Pierce, T.E., and Turner, D.B.
: US. EPA, ASRL
: AREAL, NTIS
D-40

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15.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

16.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

17.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

18.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

19.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

20.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

21.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
: PAL-2
: Point, Area, and Line Source Algorithm
; estimate short term concentrations of non-reactive pollutants
; Petersen, W.B., and Rumsey
: U.S. EPA, ASRL
: AREAL, NTIS
:PBM
: Photochemical Box Model
: estimate ozone and other smog pollutants in an urban area
: Schere, K.L., and Demerjian, K.L.
: US. EPA, ASRL
: AREAL, NTIS
: PEM-2
: Pollution Episodic Model
: predict short-term surface concentrations of two pollutants
: Rao, K.S.
: U.S. EPA, ASRL
: AREAL, NTIS
: PLUVUE-2
; Plume Visibility Model II
: predict transport and fate of point-source emissions
: Seigneur, C, Johnson, G, Latimer, D., Bergstrom, R., Hogo, H.
: SAI, Inc.
: AREAL, NTIS
 PTPLU-2

 estimate maximum surface concentrations
 Pierce, T.E., Turner, D.B., Catalano, J.A., Hale, F.V. HI
 U.S. EPA, ASRL
 AREAL, NTIS
:RAM
; Gaussian-Plume Multiple Source Air Quality Algorithm
: estimate concentrations of stable pollutants from urban sources
: Catalano, J. A., D. B. Turner, and J. H. Novak
: U.S. EPA, ASRL
: AREAL, NTIS
 ROADWAY-2

 predict pollutant concentrations near highways
 Eskridge, R.E., and Catalano, J.A.
 U.S. EPA, ASRL
 AREAL, NTIS
D-41

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22.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

23.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

24.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

25.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

26.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

27.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
:RTDM
: Rough Terrain Diffusion Model
: estimate ground-level pollutant concentrations in rough terrain

!ERT,Inc.
:NTIS
: SHORTZ

: calculate short-term pollutant concentration
: Bjorklund, J.R., Bowers, J.F.
: H.E. Cramer Co.
: AREAL, NTIS
:TECJET
: Advanced Jet Dispersion Model
: modeling free jets of toxic and flammable substances

: Technica International, Fullerton, CA
: Technica International
:TUPOS-2
: Multiple Source Gaussian Dispersion Algorithm Using On-Site Turbule
: short-term impact assessment of inert pollutants
: Turner, D.B., Chico, T., and Catalano, J.A.
: US. EPA, ASRL
: AREAL, NTIS
:UAM
: Urban Airshed Model
: computing ozone concentrations in urban areas
: Ames, J.S., Hayes, R., Myers, T.C., Whitney, D.C.
: SAI, Inc.
:NTIS
: VALLEY
•
: estimate concentrations from point or area sources in complex terra
: Burl, E.W.
: US. EPA, OAQPS
: AREAL, NTIS
D-42

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Hazardous Waste  Engineering Models
l.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

2.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

3.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor

4.
Model Name
Full Name
Purpose
Developer
Affiliation
Distributor
:EMBM
: Energy-Mass Balance Model
: simulation of industrial incineration
: Lee, C.C
 U.S. EPA, Risk Reduction Engineering Laboratory, Cincinnati
: Sonya Stelmack, U.S. EPA, RREL-Cincinnati
 CARDS
: Geotechnical Analysis for Review of Dike Stability
: evaluate earth dike structures at hazardous waste facilities

 U.S. EPA, Hazardous Waste ERL, Cincinnati, OH
 Landreth, Robert, U.S. EPA, HWERL, Cincinnati, OH
:HELP
: Hydrologic Evaluation of Landfill Performance Model
: models the hydrologic effects at hazardous waste sites
: Schroeder, P.R., Morgan, J.M., Walski, T.M., Gibson, A.C.
: U.S. EPA, Hazardous Waste ERL, Cincinnati, OH
; Landreth, Robert, U.S. EPA, HWERL, Cincinnati, OH
 SOILINER
 Soil Liner Model
 simulation of liquid infiltration through compacted soil liner

 U.S. EPA, Hazardous Waste ERL, Cincinnati, OH
 Landreth, Robert, U.S. EPA, HWERL, Cincinnati, OH
D-43

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Surface Water Model*
1.
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lACTMO
: Agricultural Chemical Transport Model
: nonpoint source model applicable to agricultural areas
: Frere, M.H.; Onstad, C.A.; Holtan, H.W.
: U.S. Dept. of Agriculture, Agricultural Research Service
: Agriculture Research  Service, U.S.D.A., Hyattsville, MD
:AGRUN
: Agricultural Watershed Runoff Model for the Iowa-Cedar River Basins
: nonpoint source model applicable to agricultural watersheds
: Roesner; Zison; Monser; Lyons
: Water Resources Engineers, Inc.
:ARM-2
: Agricultural Runoff Model
: estimate pollutant loadings in agricultural areas
; Crawford, N.H., Donigian, A.S., Jr.
: U.S. EPA, ERL-Athens, GA
:CAFE

: two dimensional hydrodynamics simulation in estuaries
: Pagenkopf, J.R., Christodonlou, G.C., Pearce, B.R., Connor, J.J.
; Dept. of Civil Engineering, MIT, Cambridge, MA
; Pagenkopf, J.R., Dept. of Civil Eng., MIT, Cambride, MA
:CHNHYD
: Channel Hydrodynamic Model
: simulating flows and water surface elevation in river networks
; Yeh, G.T.
: Environmental Sciences Division, Oak Ridge National Laboratory, TN
 Yeh, G.T., ESD, Oak Ridge National Laboratory, TN
rCHNTRN
: Channel Transport Model
: sediment & contaminant transport in rivers & well-mixed estuaries

: Environmental Systems Division, Oak Ridge National Laboratory
: Yeh, G.T., ESD, Oak Ridge National Laboratory
: CREAMS
: Chemicals, Runoff, and Erosion From Agricultural Management Systems
: estimate pollutant loadings from agricultural areas
: Knisel, W.G.
: U.S. Dept. of Agriculture, Science and Education Administration
: Walter Knisel, Southeast Watershed RL, U.S.D.A.
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:CTAP
: Chemical Transport and Analysis Program
: concentration distributions in water column & sediments
i
: HydroQual, Inc.
: Gulledge, William, Chemical Manufacturers Association
 DWOPER
 Dynamic Wave Operational Model
 simulating river flow
 Fread, D.L.
 Hydrologic Research Laboratory, National Weather Service, NOAA
 Fread, D.L., NWS, NOAA, Silver Spring, MD
iFETRA

: transport of contaminants, sediments, in well-mixed estuaries
; Onishi, Y., Thomson, F.L.
: Battelle, Pacific Northwest Laboratories
: Onishi, Y., Battelle, Pacific Northwest Laboratories, WA
:HEC-2

; water surface profile in rivers for a steady flow discharge
: Hydrologic Engineering Center
: U.S. Army Corps of Engineers, Davis, CA
: HEC, U.S. Army Corps of Engineers, Davis, CA
:HEC-6

: profile water surface and stream bed
: Hydrologic Engineering Center
: U.S. Army Corps of Engineers, Davis, CA
: HEC, U.S. Army Corps of Engineers, Davis, CA
iMEXAMS
: Metals Exposure Analysis Modeling System
: fate and transport of metals in aquatic systems
: Felmy, A.R., Brown, S.M., Onishi, Y., Argo, R.S., Yabusaki, S.B.
: Battelle Pacific NW Lab
: MICHRIV

: transport in water & sediment in streams & nontidal rivers
: DePinto, J.V., Richardson, W.L., Rygwelski, K.
: U.S. EPA, ERL-Duluth
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:NPS

: estimate nonpoint source pollutant loads in urban and rural areas
: Donigian, A3., Jr., and Crawford, N.H.
: U.S. EPA, ERL-Athens,GA
:SEDONE

: simulating hydrodynamic flow and sediment transport
: Hetrick, D.M., Eraslan, A.H., Patterson, M.R.
: Oak Ridge National Laboratory, TN
;SERATRA
: Instream Sediment-Contaminant Transport Model
: transport of contaminants & sediments in rivers
: Onishi, Y., Wise, S.E.
: Battelle, Pacific Northwest Laboratory for U.S. EPA
: Onishi, Y., Battelle, Pacific Northwest Laboratory
:SLSA
: Simplified Lake/Stream Analyses
: concentration distribution in water and sediments of rivers & lakes

; HydroQual, Inc.
: Gullege, William, Chemical Manufacturers Association
iTDMECS
: Three-Dimensional Model for Estuaries and Coastal Seas
: flow and contaminant transport in estuaries and coastal seas
: Leendertse, J.J., Liu, S.K.
: Rand Corporation, Santa Monica, CA
: Liu, David, Rand Corporation, Santa Monica, CA
: WATFLOW
»
: hydrodynamic flow in rivers and estuaries
: Leendertse, J.J.
: Rand Corporation, Santa Monica, CA
; Charles Sweeney, Engineering Hydraulics, Inc., Redmond, WA
: WQSM
; Water Quality Simulation Model
: flow and transport in well-mixed estuaries and costal seas
: Leendertse, J.J.
: Rand Corporation, Santa Monica, CA
: Liu, David, Rand Corporation, Santa Monica, CA
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Drinking Water Models

1.
Model Name   : PCAS
Full Name     : Packed Column Air Stripping Model
Purpose       :
Developer     : Cummins, M.D.
Affiliation    : U.S. EPA, Office of Drinking Water, Cincinnati, OH
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