=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #217
—January 23, 1991—
News and resources for environmental justice.
——
Environmental Research Foundation
P.O. Box 5036, Annapolis, MD 21403
Fax (410) 263-8944; Internet: erf@igc.apc.org
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WHY PLASTIC LANDFILL LINERS ALWAYS FAIL.
In the landfill business, government and industry say plastic
liners are going to save the day. For example, U.S. Environmental
Protection Agency (EPA) and industry both argue that incinerator
ash can be safely “disposed of” in a double-lined ash “monofill.”
A “monofill” is a landfill that contains only ash, no raw
garbage. Like any other landfill, the basic design is a bathtub
in the ground. The bottom of the bathtub is formed by a huge
sheet of plastic. In an expensive landfill, you have two sheets
of plastic separated by about two feet of sand and gravel–thus
creating one bathtub inside another bathtub. Therefore, a
doublelined ash monofill is a landfill (which is really just a
polite word for a dump) in the form of a bathtub created by two
plastic liners, containing incinerator ash and nothing else.
The theory behind the monofill is that ash contains only small
amounts of aggressive organic chemicals that might eat a hole in
the plastic liner, so the plastic liner will remain intact and
protect us against the lead and cadmium and other toxic metals
contained in the ash. (See RHWN #92.) As always, the key question
is: what is the duration of the hazard and what is the duration
of the protection provided by the plastic liner? (The “cap” or
umbrella covering a landfill will also be made of the same
plastic, so a landfill is really a “baggie” in the ground,
containing toxins. What is the lifetime of this baggie? How long
will it protect us?)
What is the duration and nature of the hazard from metals in
incinerator ash? As we saw earlier (in RHWN #92) incinerator ash
is rich in toxic metals. For example, it typically contains
anywhere from 3000 parts per million (ppm) to 30,000 ppm of lead.
U.S. Environmental Protection Agency Region (Boston), and the
Harvard University School of Public Health have recommended a
cleanup action level of 1000 ppm for lead in soil–in other
words, they recommended that remedial action, as would be needed
at a Superfund site, should be undertaken wherever lead in soils
exceeds 1000 ppm.[1] In recommending the 1000 ppm action level,
EPA and Harvard wrote, “While we believe a greater margin of
safety would be achieved with an action level of 500 ppm, we
think it necessary to set priorities for remedial activity.”
(What they meant was that there are so many places in urban
America where there is 500 ppm lead in soil that EPA would be
overwhelmed with work if 500 ppm were set as the threshold for
remedial action–so 1000 ppm is a more “realistic” cleanup action
level even though it’s not as safe as the nation’s children
really need it to be.)
Given that EPA Region I and the Harvard School of Public Health
have recommended that Superfund-type cleanup be initiated
whenever soils contain more than 1000 parts per million (ppm) of
lead, we know immediately that every ash monofill will have to be
cleaned up at some time in the future because all incinerator ash
contains more than 1000 ppm lead. (Ash also contains dangerous
amounts of other toxic metals–cadmium, arsenic, chromium, and
perhaps others, so lead is not the only reason why a cleanup
might be needed.) Therefore, when we create ash monofills we know
we are creating Superfund sites that our children will pay
for–either in damage to their brains and nervous systems, or in
enormous outlays of money–or both.
Because lead and cadmium and other metals never degrade into
anything else, but remain toxic forever, the duration of the
hazard is perpetual, everlasting, eternal. The danger will never
go away.
The incineration industry, and its acolytes in government, argue
that the plastic liners will protect us and our children forever.
Unfortunately, this idea is based on a misunderstanding (or more
likely an intentional misrepresentation) of what happens to
plastics as they get older. Plastics are not inert; they do not
stay the same as time passes. They change. They come apart
spontaneously.
A recent book by Deborah Wallace, Ph.D., describes this process
well.[2] The book is about the dangers of plastics in fires, but
in telling the story of “Why today’s fires are so dangerous,”
(the answer is because burning plastics give off toxic gases that
kill people who breathe them), Dr. Wallace included a section on
the makeup of plastics at the molecular level, which helps us
understand why all plastics eventually fall apart.
The building blocks of plastics are found in natural gas, coal,
and wood, but the major source is oil. Oil (like coal and natural
gas) is a mixture of molecules of different sizes and structures.
To separate out the different molecules, crude oil is distilled
in an oil refinery. The oil is boiled and smaller, lighter
molecules are separated from the larger, heavier molecules. The
heavier molecules are then “cracked” to break up the large, heavy
molecules into smaller, lighter molecules.
The result of this distillation and cracking is organic
chemicals, which is the name for chemicals containing carbon and
other elements (chiefly hydrogen, oxygen, and nitrogen). These
organic chemicals form the building blocks of pesticides, glues,
and plastics. Other chemicals (such as chlorine and lead) are
added to give the raw materials new characteristics (strength,
stiffness, color, and so forth).
After the building blocks are manufactured, they are turned into
plastic resin by a process called polymerization. A polymer is a
large, organic, chain-like molecule made of repeated units of
smaller molecules. Polymerization usually requires heating the
raw materials in the presence of helper chemicals called
catalysts, until the building blocks form long chains. Even with
the catalysts, a great deal of heat is used in the polymerization
process. “Because of this heat, the long chains, even during
manufacture, may decompose slightly and have defect points along
them,” Dr. Wallace explains. The defect points are in the
chemical bonds, which absorb the energy used in the manufacturing
process. The law of conservation of energy states that the amount
of energy in a system after the reaction is the same as the
amount of energy before the reaction. The large amounts of energy
(heat) thus must go somewhere; they go into the bonds between the
atoms of the plastic and are stored there. But nature does not
favor this gain of energy–nature favors low energy chemical
bonds, and high energy bonds tend to release their energy by
breaking spontaneously. These are defect points. Although polymer
scientists have striven to reduce the number of defect points,
they have not been able to completely eliminate them from
synthetic polymers.
Dr. Wallace continues, “The physical and chemical defects that
are produced by ordinary processes in the manufacture and use of
plastics demonstrate the fragile and unstable character of these
long chains of molecules that are joined by high energy chemical
bonds. When the resin is further processed to become the finished
marketable product, additional defect points are created because
the product is again heated and handled.”
As time passes, plastics decompose–their molecules come apart
spontaneously–beginning at the defect points. Polymer scientists
refer to this decomposition as “aging.” All plastics “age” and
there is nothing that can be done about it. Within a few years
(at most a few decades), all plastics degrade, come apart, and
fail. They become brittle, lose their strength, crack, break into
fragments. At that point, any protection the plastic may have
afforded against the toxic dangers lurking in an ash monofill is
gone. By that time, the people who created the ash monofill will
have taken their profits and left town, but the deadly residues
they leave behind–the ash–will remain to plague the community
forever, poisoning the community’s children with toxic lead and
other metals.
The only affordable solution to this problem is a simple one:
prevent the creation of incinerator ash.
–Peter Montague, Ph.D.
===============
[1] P.L. Ciriello and T. Goldberg, “Lead-contaminated Soil
Cleanup Draft Report” which appears as Appendix E in: Agency for
Toxic Substances and Disease Registry, THE NATURE AND EXTENT OF
LEAD POISONING IN CHILDREN IN THE UNITED STATES: A REPORT TO
CONGRESS (Atlanta, Ga: Agency for Toxic Substances and Disease
Registry, Public Health Service, U.S. Department of Health and
Human Services [1600 Clifton Rd. -Mail Stop E-33, Atlanta, Ga
30333; phone (404) 639-0730], July, 1988). Free while supplies
last.”
Descriptor terms: epa; landfilling; plastic liners; harvard
university school of public health; studies; remedial action; ash
monofills; toxic metals; deborah wallace; polymerization; leaks;