United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-88/042 Aug. 1988
Project Summary
Technical Considerations for
De Minimis Pollutant Transport
Through Polymeric Liners
R. W. Telles, S. L. Linger, H. R. Lubowitz, and Hinton K. Howard
Based on an extensive survey of
the literature, this report provides a
technical basis for predicting the
transport of fluids through polymeric
liners used to confine pollutants in
landfills and impoundments. When a
mixture of organic fluids, water, salts,
and other substances are confined
by an intact liner, first the organic
fluids permeate according to their
mobilities, then water. Salts,
macromolecules, and micro-
organisms remain confined. These
phenomena indicate that fluids are
transported by the permeation
mechanism and that properly
selected and installed liners made
with commodity resins can be
effective. Organic fluids can be one
of the major factors in determining
de minimis values. These permeation
rates can be appreciable; therefore,
impoundments with organic fluids
must be selectively designed so that
adequate protection of health and
the environment is maintained.
This Project Summary was
developed by EPA's Hazardous Waste
Engineering Research Laboratory,
Cincinnati, OH, to announce key
findings of the research project that
is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
Polymeric lined landfills and
impoundments are regulated under
RCRA and associated background and
guidance documents. Pursuant to
Section 3004[0] and 3015 of the
Hazardous and Solid Waste Amendments
of 1984 and minimum guidance
technology for double-liner systems,
polymeric liners must prevent migration
of constituents of the waste liquid into the
liner during the period the unit remains in
operation (including any post-closure
monitoring period) except for de minimis
leakage. EPA recognizes that polymeric
liners will not always have zero leakage
and that cte minimis leakage may occur.
De minimis leakage can occur as a result
of vapor passing through the liner, very
small imperfections in the liner that occur
very rarely, or a seam that has a very
small crack or hole.
The full report discusses some
technical considerations regarding de
minimis transport rates for polymeric
liners. The considerations stem from an
extensive review of the technical
literature. A wide range of published
information was reviewed, including
technical specifications in vendor
publications pertaining to liners.
Properly installed and functioning
polymeric liners are expected to allow the
permeation of organic liquids first,
followed by water. They are expected to
contain dissolved inorganic compounds
such as salts.
EPA believes that current state-of-
the-art technology for FML installation
allows for hazardous waste management
units to be built that will have very low
leakage rates at installation. EPA does
not have a specific maximum de minimis
leakage rate that can be recommended.
However, based on currently available
preliminary field data, laboratory test
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results, and professional judgment. EPA
believes that de minimis leakage should
be approximately 1 gallon/acre/day or
less. This rate should not be taken as a
hard and fast rule because there are
conditions where vapor transmission
potentially could exceed this value. Also,
this value does not apply to organic
liquids, many of which can permeate an
FML independently of the water in waste
liquid.
It is proposed that the cte minimis rate
for organic fluids can be based on their
rates of permeation as determined by
experiment; or in the absence of
experimental data, as estimated by the
permachor method, which is described in
this report.
Because the total rate of flow through
liners can be comprised of permeation
plus flow through flaws, the full report
also describes methods for estimating
the rate of fluid flow through liner flaws,
using the Poiseuille equation for small
flaws and the Bernoulli equation for large
flaws.
Procedures
Literature Search
The preliminary search of Chemical
Abstracts, Applied Science and
Technology, and Dissertation Abstracts
International provided the basis for the
key words to be used in the extensive
computer search for relevant papers. The
computer search included NTIS,
SCISEARCH, ENVIROLINE, Federal
Research in Progress and others.
Permachor Method
In general, the permeability of a given
penetrant in a polymer is derived from
transmission or sorption-desorption
experimental data obtained under
exacting experimental conditions
However, for polyethylene and
polypropylene, a simplified empirical
method has been developed to estimate
the permeability through these materials
based on a number called the permachor
which is based on the molecular
structure of the permeant. These
empirical numbers are derived from
actual test data and assigned to each
atom or atomic group in the repeating
unit of polymer molecules.
In the full report examples are given to
show the calculation of permeation rates
using permachor values. Comparisons to
experimentally determined rates are
shown, and the restrictions regarding the
utility of permachor calculations are
discussed.
Flow Through Liner Flaws
Analysis of circular flaws in fre
draining liner systems is based on th
Bernoulli equation for large flaws and th
Hagen-Poiseuille equation for sma
flaws. According to the Bernoul
equation, flow is dependent upon th
hole diameter and the hydraulic head t
the one-half power According to th
Poiseuille equation, flow through pinhole
is dependent upon the effluent density
hole diameter, hydraulic head, line
thickness, and effluent viscosity
These equations are discussed, alom
with their limitations Comparisons c
measured and calculated flow rates an
given.
R. W. Telles, S. L Unger,and H. R. Lubowitz are with Environmental Protection
Polymers, Inc., Hawthorne, CA 90250. The EPA author, Hinton K. Howard, is
with the Hazardous Waste Engineering Research Laboratory, Cincinnati, Oh
45268.
Car/ton C. Wiles is the EPA Project Officer (see below).
The complete report, entitled "Technical Considerations for De Minimis Pollutant
Transport Through Polymeric Liners," (Order No. PB 88-238 3321 AS; Cost.
$14.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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