UNITED STATES EN V i cONi4c N < -•>.,
VV A 3 H! N G i O N C .'J 2046 "
16, 1987
Honorable Lee M. Thomas SAB-BC-87-019
Administrator
U. S. Environmental Protection Agency ^ -•••• ^--
401 M Street, S. W. '": *^''••'••--
Washington, D, C. 20460
Dear Mr. Thomas s
The Science Advisory Board has conducted a series of scientific reviews
of Agency research programs that have proven to be a highly useful means of
assessing the quality and relevance of existing research, identifying
research needs and involving the scientific community in the research
planning process. Such reviews have also aided internal corouni cation
within the Office of Research and Development (OBD) and between ORD and the
program offices.
The specific research programs SAB has reviewed since January 1936
include the following;
« Dioxins
• B i ©technology
* Extrapolation Modeling
• Water Quality
• Ecological Risk Assessment
• Alternative Hazardous Waste Control Technologies
* Superfund Innovative Technologies Evaluation
» Indoor Air Research Plan
* Integrated Air Cancer Project
» Radon Mitigation Program
» FY '88 Budget Proposal for the Office of Research and Development
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In addition, the Science Advisory Board is scheduled to conduct scientific
reviews for the following research programs later this fiscal year: advances
in neurotoxioology, health effects of disinfectants and disinfectant by-
products; acid deposition; radon and indoor air; biological control agents;
effectiveness of asbestos removal processes; control of water quality in water
distribution systemsj land disposal; and waste minimization.
The purpose of presenting this information is to inform you that such
reviews have focused both the SAB'S and the Agency's thinking on research
plans and needs to a degree never before achieved through preparation and
review of the Five Year Research and Development Plan (Research Outlook).
As you know, Congress has required that the Agency provide the SAB with the
opportunity to review the Plan. The Board believes that its extensive
research progratti reviews fulfill the spirit and intent of Congress for SAB
oversight of the Agency's research program, Cewtisnts on specific issues in
the five year plan have also been addressed in individual research program
reviews.
The Board reiterates its long-standing support of research directed to
address problems beyond the immediate regulatory needs of the Agency. It is
preparing a separate report on this and other issues as it reviews the proposed
research budget for Fiscal Year 1988.
Sincerely,
Norton Nelson
Chairman
Science Advisory Board
>\
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The attached report contains more detailed responses to
these issues.
We are pleased to have had the opportunity to be of service
to the Agency and look forward to a written response to our
report,
Sincerely,
Norton Nelson, Chairman
Executive Committee
science Advisory Board
Raymond Loehr, Chairman
Environmental Engineering Committee
Kjca Advisory Board
/ i -
Paul Roberts, Chairman
Unsaturated Zone Code Subcommittee
Environ»ental Engineering committee
cc: W. Porter
S, Lowrance
J. Denit
s. Weil
M. Strauss
Z. Saleem
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The Subcommittee believes that there are no serious problems
associated with treating the fluid as incompressible, isothermal,
and homogeneous. The acceptability of all the other assumptions
hinges on the application of the model. certain classes of
phenomena ar« not well enough understood to be incorporated into
a management model of the kind reviewed here. Because of the
importance of these phenomena to site-specific applications,
there is an urgent need for scientific research to clarify the
scientific principles underlying these phenomena. Such research
would have benefits beyond this model. The FECTUZ model package
is also subject to limitations imposed by its simplifying
assumptions and the scarcity of data necessary for parameter
estimation* Both versions of. the model are incomplete in the
sense that several potentially important governing processes are
neglected altogether. The Subcommittee believes these
limitations are not so debilitating as to preclude its employment
for generalized regulatory development applications, but believes
that the inability to take into account several potentially
relevant processes casts serious doubt on the advisability of
site-specific applications, it is recommended that the Agency
mount directed and continuing efforts (a) to improve the
knowledge base concerning relevant processes which have been
neglected on grounds of inadequate understanding,and (b) to seek
expert consensus in these areas, especially biotransformation,
immiscible transport, and fracture transport.
The Subcommittee finds that for the intended tasks in
regulatory development, the composite model consisting of FECTUZ-
A and EPA-SMOD is acceptable from the standpoint of simplicity
and computational ease. where Monte Carlo replication of the
model is planned, the overall uncertainty of the transport model
should be addressed because the Monte Carlo methodology is not
able to account for uncertainties arising from incompleteness or
deficiencies in the underlying model. However, for site-specific
decisions where the accuracy and completeness of representation
of transport and transformation processes is of paramount
importance, the FECTUZ model seems bound to be inadequate,
especially the analytical version owing to its implicit
simplifications and its inability to take into account temporal
variations, site-specific conditions and heterogeneity. The
Office of Solid waste should take special care to warn potential
users against site-specific applications of the composite model,
because there is a substantial danger that such usage could be
misleading and detrimental to the protection of groundwater
quality.
Additionally, the Subcommittee has expressed concerns
and made suggestions relating to how the Agency establishes the
need for the development, of a new model, how existing models are
evaluated, and on the existence and use of adequate in-house
capability for evaluating issues related to transport model
development and application.
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