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#109 - The Catch-22s Of Landfill Design, 25-Dec-1988

The waste hauling industry knows that all landfills will eventually
leak because their own industry trade journals are now telling the
story. WASTE AGE is the main magazine for the waste industry. The
editors of WASTE AGE are not sympathetic to environmental groups. For
example, it was in WASTE AGE'S columns that you may have read,

"The NIMBY [not in my back yard] syndrome is a public health problem of
the first order. It is a recurring mental illness that continues to
infect the public.

"Organizations that intensify this illness are like the viruses and
bacteria which have, over the centuries, caused epidemics such as the
plague, typhoid fever, and polio.

"....It is time solid waste management professionals stopped wringing
their hands and started a campaign to wipe out this disease." (WASTE
AGE, Mar., 1988, pg. 197.)

Clearly WASTE AGE is no friend of the grass roots environmental
movement. Yet it has been publishing articles that say what we've been
saying all along: the security and safety of landfills is dependent
upon the landfill cap, and the landfill cap is inevitably destroyed by
natural forces.

WASTE AGE has run a series of articles over the past two years saying
why landfills will inevitably leak, and suggesting that the only
solution to the problem is perpetual maintenance of the closed
landfill. Since humans have no experience maintaining anything in
perpetuity, perpetual maintenance is an untested and unproven, and, one
can only say, silly non-solution. If we took it seriously, perhaps we
would develop a large army of landfill maintainers whose only job in
life will be to maintain the toxic garbage left behind by their parents
and their parents' parents and their parents' parents' parents and so
on for generation after generation.

Despite the silly suggestion that perpetual maintenance of landfill
caps is a way out of our present garbage problem, these articles
contain much good information about why landfills leak.

Remember, a landfill is nothing more than a bathtub in the ground
(perhaps, in the case of a double-lined landfill, one bathtub inside
another). A bathtub will leak if its bottom develops a hole, or it can
simply fill up with water (for example, rainfall) and leak over its
sides. Either way, a landfill can contaminate the local environment.
Therefore, a "cap" is placed over the landfill when the landfill is
full. The "cap" is supposed to serve as an umbrella to keep rain out,
to keep the bathtub from spilling over its sides.

Writing in WASTE AGE, Dr. David I. Johnson and Dr. Glenn R. Dudderar of
the Michigan State University Department of Fisheries and Wildlife,
have argued,

"There is evidence that the engineered integrity of a cap will not be
maintained over the landfill's extended life." (This is somewhat fancy
language for "All landfills will eventually leak.")

Johnson and Dudderar go on to say, "Regulations may require bonding for
five to 20 years. Yet from a biological and geophysical point of view
this time period is a totally inadequate maintenance
requirement." (Translation: It may take nature more than 20 years to
destroy a landfill cap, but nature has all the time in the world, so
you'd better be prepared to maintain a landfill for the long haul--

Catch 22 #1: A landfill cap is intended to be impermeable--to keep
water out. This means water is supposed to run off the surface. But
this, in turn, invites soil erosion. "But in the runoff process, cap
soil will be carried with the runoff, causing sheet and rill erosion
and, ultimately, gullying of the cap." When you get gullies in the cap,
it's all over.

Other physical forces working constantly to destroy a landfill cap are
freezethaw and wet-dry cycles. Soil shrinkage during dry weather can
cause cracks. Rain penetrates the cracks. In winter, rain freezes to
ice and expands, widening the cracks. And so on, year in, year out,
century after century. The cracks not only let in water, they also
provide pathways for plant roots and for burrowing animals.

Catch 22 #2: To minimize soil erosion, and to minimize changes due to
wet-dry cycles, you need to establish vegetation on the cap. However,
plants maintain their physical stability, and they gather water and
nutrients, through roots, which can penetrate a landfill cap,
destroying the cap's integrity. Furthermore, plants provide cover (and
food) for burrowing animals, which then burrow into the cap, destroying

A study of a solid radioactive waste landfill reveals that mice,
shrews, and pocket gophers can move 10,688 pounds (5.3 tons) of soil to
the surface per acre per year. "Similar activity would have a dramatic
impact on landfill cap integrity," Johnson and Dudderar observe.
Burrowing animals of concern include woodchucks, badgers, muskrats,
moles, ground squirchipmunks, gophers, prairie dogs and badgers. Clay
presents little barrier to such animals; "synthetic liners, measured in
mils [of thickness], are not likely to impede these same mammals,"
Johnson and Dudderar observe. Non-mammals are also a problem: crayfish,
tortoises, mole salamanders, and "a variety of worms, insects and other
invertebrates" can make holes in a landfill cap.

Earthworms alone can have a devastating impact on a landfill cap.
Earthworms pass two to 15 tons of soil through their digestive tracts
per acre per year. "The holes left as they move through the soil to
feed increase water infiltration," Johnson and Dudderar comment. They
give evidence that worm channels allowed plant roots to grow to a depth
of nine feet in Nebraska clay soils.

In a section called "The fundamental dilemma," Johnson and Dudderar sum

"At this point you may well say: 'If we plant, we're encouraging plant
and animal penetration of the clay cap. If we don't plant, we get
erosion or freeze-thaw destruction of the cap.'

"Unfortunately, that is one of the fundamental dilemmas left us by the
normal processes of change in the natural world, be they the
progressive conversion of a grassy field to a forest or the utilization
of cracks in concrete sidewalks by ants and dandelions.

"This same successional development process, so intensively studied in
the ecological literature, will detrimentally affect long-term landfill
integrity." So there you have it, right from the pages of Waste Age:
the forces of nature, left to themselves, will destroy landfill caps,
the key element intended to prevent landfills from leaking.

What hope is there? Perpetual care. A perfectly silly idea. What
reasonable hope is there? None whatsoever. All landfills will
eventually leak. Happy new year.

For further information, see: David I. Johnson, "Caps: The Long Haul,"
WASTE AGE March, 1986, pgs. 83-89; David I. Johnson, "Capping Future
Costs," WASTE AGE August, 1986, pgs. 77-86; David I. Johnson and Glenn
R. Dudderar, "Can Burrowing Animals Cause Groundwater Contamination?"
WASTE AGE March, 1988, pgs. 108-111; see also David I. Johnson and
Glenn R. Dudderar, "Designing and Maintaining Landfill Caps for the
(April, 1988), pgs. 34-40. Dr. Johnson [phone 517/353-1997] and Dr.
Dudderar [phone 517/353-1990] are with Department of Fisheries and
Wildlife, Michigan State University, East Lansing, MI 48824.

--Peter Montague


Descriptor terms: landfilling; caps; capping; failure mechanisms;
failure modes;