Throughout the 1960s and 1970s, engineers and scientists employed by
the U.S. Atomic Energy Commission (AEC), and by private manufacturers
of nuclear power plants, like Westinghouse, argued that the solution to
radioactive waste disposal was to mix the stuff with some self-
hardening glop (asphalt, concrete, epoxy, you name it) and bury it in a
shallow grave, a landfill.
Starting in 1978, when Love Canal was discovered, the private producers
and government regulators of hazardous chemical wastes argued that the
solution to their problem was to mix it with some self-hardening glop
(asphalt, concrete, epoxy, you name it) and bury it in a shallow grave.
Now that the people who used to make nuclear power plants are making
municipal solid waste incinerators instead, the engineering world is
buzzing with a "new" idea: the solution to the problem of toxic ash
waste is to mix the stuff with some self-hardening glop (asphalt,
concrete, epoxy, you name it) and bury it in a shallow grave.
In the case of radioactive waste, the idea of self-hardening glop and
shallow disposal was completely rejected. Instead, the decision was
made to let the earth itself provide a barrier between the wastes and
the environment that people inhabit. So the current plan is to bury
high-level radioactive wastes half a mile below ground in artificial
caves made for that purpose. As an added measure of protection, the
radioactive material may be solidified with some self-hardening glop
(molten glass has been discussed for this use for 20 years) before it
is lowered into the cave, but the main barrier between humans and the
radioactive danger is to be a half-mile of solid earth.
The reason self-hardening glop was rejected for radioactive wastes is
that there is no way to prove how long any self-hardening agent will
remain solid. A block of concrete-and-mixed-waste today may crack and
break into pieces within a few decades, eventually turning back into
toxic sand, depending on what happens to it (in terms of chemical
environment, physical environment and geological forces) in the future,
and depending on what chemicals the original waste contained. The same
uncertainty plagues epoxy, asphalt, or any other material you can name.
And there is no way to test the breakdown of self-hardening materials,
except to give it a try, and then wait and see what happens. This
amounts to conducting an experiment on our children, or upon THEIR
children, and it is obviously immoral and wrong. Who gives incinerator
companies the right to place toxic time bombs in the ground, waiting to
contaminate the nation's water supplies and soils with a potent
neurotoxin like lead? Our children are already dangerously contaminated
with lead (see RHWN #189). The chemical waste producers are willing to
experiment on our children, and the garbage incinerator people seem
positively eager to conduct such experiments--they're ready to bury new
mixtures of glop and highly toxic ash in shallow graves tomorrow
morning, if we'll let them.
In the case of solidifying hazardous chemical wastes, the EPA (U.S.
Environmental Protection Agency) has set up a program called SITE
(Superfund Innovative Technology Evaluation--see RHWN #150) to evaluate
different kinds of glops and their abilities to solidify different
kinds of hazardous wastes. The program began three years ago and will
run for a decade or more. The SITE program recognizes that each kind of
waste requires a different kind of glop, and many wastes can't be
successfully solidified at all. Predictably, the SITE program has been
unable to answer the key questions that plagued all proposals a decade
earlier to solidify radioactive waste: the Congress's Office of
Technology Assessment evaluated solidification technologies used in
Superfund cleanups (see RHWN #87) and pointed out (a) There is no
standard test for deciding whether a waste has been "successfully"
solidified; and (b) There is no way to gather data on the long-term
stability of a solidified waste except to wait and see what happens as
time passes. In other words, a trial-and-error experiment on our
children is the only way to find out if solidifying toxic wastes really
The garbage incinerator people don't seem to care about these
insurmountable technical difficulties. They argue strenuously, in
public meetings, in newspaper articles, and in flawed technical
articles  that they have found a solution to the toxic incinerator
ash problem; in fact, they argue the ash isn't really "toxic" at all,
even though it has 2,500 to 6,000 parts per million (ppm) of toxic lead
in it. (Some ash has upwards of 20,000 ppm lead in it.) The garbage
incinerator industry is now conducting a nationwide PR campaign to
convince everyone that incinerator ash has "pozzolanic"
characteristics, which is to say the stuff will harden like cement, and
that this will prevent the toxic metals in the ash from escaping into
the environment where it would make humans sick. They have a small
amount of data showing that some ash wastes, mixed with lime or cement,
do harden, but they have absolutely no data on the long-term
reliability of the hardening process because they have not been doing
it for long. They are simply willing to wager our children's health and
safety that their process will remain stable for the duration of the
hazard, which is thousands of years. (What they're really betting is
that they'll be gone by the time serious problems become apparent--it's
the familiar "dump now, let our children pay later" principle that
brought us Love Canal and every other Superfund dump.) It is a travesty
of good science and engineering, and serious violation of public health
principles, which demand "safety first."
By reading engineering manuals and textbooks  on cement, one can
readily compile a list of known factors that make it impossible for
cement and ash mixtures to protect public health reliably in the long
run (we'll only list a few here):
1) Cement is a mixture of four main chemical compounds; to harden
satisfactorily and remain strong, the four chemical compounds must be
present in the proper proportions, and other chemicals (such as
sulfates, and organic material), which interfere with the reactions,
must NOT be present. 
The "aggregate" (usually gravel when cement is made on a construction
site, but ash in the case of a toxic ash solidification project) must
be uniform in size and chemical composition. This requirement is
impossible to meet in the case of mass burn ash.
The chemical composition of incinerator ash varies widely from place to
place and day to day (even hour to hour). This is a natural result of
the garbage itself varying widely from place to place and day to day.
One day the garbage is mostly industrial trash; another day it's full
of organic matter. There is no way around this problem in a mass burn
incinerator (one that burns garbage without any processing before the
Other factors that cause variability in the ash are the incinerator
design, the actual combustion conditions (which vary), and the air
pollution controls (for example, presence or absence of lime
2) Incinerator ash has a highly variable salt content, and many kinds
of salts interfere with the proper hardening of cement.
3) It is widely agreed that an alkaline environment must be maintained
to prevent leaching of metals from ash, even solidified ash. Since rain
is acid (not alkaline) by nature, rain will eventually change any
alkaline landfill environment into a neutral, or slightly acidic
environment, and leaching of metals will then proceed.
 For example, see footnotes 1 and 2 in RHWN #191 last week.
 Frederick S. Merritt. STANDARD HANDBOOK FOR CIVIL ENGINEERS. Third
Edition. New York: Mcgraw-hill, 1983), pgs. 5-1 through 5-15.
 F. M. Lea. THE CHEMISTRY OF CEMENT AND CONCRETE. Third Edition. New
York: Chemical Publishing Co., 1971. See, for example, chapter 21, "The
Examination of Concrete Failures" and Chapter 10, "The Setting and
Hardening of Portland Cement."
Descriptor terms: incinerator ash; msw; incineration; cement; concrete;
solidification; stabilization; hlw; radioactive waste; superfund
innovative technology evaluation; epa; toxic waste; alternative