Stats on Trash Generated Yearly
Americans generate four pounds of trash per
day per person
600,000 tons per day
210 million tons per year!
56 million tons 27% recycled
or composted (yard waste)
Trash production has increased 3x since 1960
27% recycled composted
16% burned
57% buried in landfills (2x
from 1960)
Steps to take in building a landfill
Local Government Responsibility:
1. Conduct environmental impact study:
A. Determine if there is sufficient land for the landfill.
- Account of landfill and support areas such as runoff collection
ponds, leachate, collection ponds, drop-off stations, areas for borrowing
soil and 50- to 100-foot buffer areas.
B. Determine the composition of the underlying soil
and bedrock.
- Provide for a watertight rock layer so to prevent any
leakage from reaching groundwater. Prevent fractures from forming
in the bedrock layer so an accurate prediction of the flow of waste can
be made. Sink wells at various points around the site to monitor the
groundwater or to capture any escaping wastes.
C. Provide a continuous study of the flow of water over
the area.
- Observe where the water flows to.
It is not favorable for the excess water from the landfill draining on to
neighboring property or vice versa. Similarly, a regulation of potential
leakage is necessary so that contaminates don’t enter the groundwater
or watershed.
D. Keep area as isolated as possible.
- Know the potential effects of the landfill and possible
contamination on local wildlife and try to keep away from areas such as
nesting areas of local or migrating birds or fisheries.
E. Stay way from areas that contain any historical or
archaeological artifacts.
2. Provide a permit.
3. Raise money to build and operate landfill.
*note: Once a landfill is filled, it must be maintained for 30 years
by law. This includes methane removal and water monitoring. These
areas are then made into parks or golf courses.*
Parts/Makeup of Landfill
Bottom Liner System
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Model Landfill
The bottom liner prevents the trash from coming in contact with the
outside soil, particularly the groundwater. The bottom liner can either
be synthetic plastic (polyethylene, high-density polyethylene, polyvinylchloride)
or clay. It is usually 30-100 mils thick. The plastic liner may
be also be combined with compacted clay soils as an additional liner, and
it may also be surrounded on either side by a fabric mat (geotextile mat)
that will help to keep the plastic liner from tearing or puncturing from
the nearby rock and gravel layers.
What can go wrong?
Natural clay is often fractured and cracked. A mechanism called diffusion
will move organic chemicals like benzene through a three-foot thick clay
landfill liner in approximately five years. Some chemicals can degrade clay.
The very best landfill liners today are made of a tough plastic film
called high density polyethylene (HDPE). A number of household chemicals
will degrade HDPE, permeating it, making it lose its strength, softening
it, or making it become brittle and crack. Not only will household chemicals,
such as moth balls, degrade HDPE, but much more benign things can cause
it to develop stress cracks, such as, margarine, vinegar, ethyl alcohol,
shoe polish, or peppermint oil.
Even a composition layer can be faulty. A Composite liner is
a single liner made of two parts, a plastic liner and compacted soil (usually
clay soil). Reports show that all plastic liners (also called Flexible
Membrane Liners, or FMLs) will have some leaks. It is important to realize
that all materials used as liners are at least slightly permeable to liquids
or gases and a certain amount of permeation through liners should be expected.
Additional leakage results from defects such as cracks, holes, and faulty
seams. Studies show that a 10-acre landfill will have a leak rate somewhere
between 0.2 and 10 gallons per day.
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Cells (Old and New) Click Here to See the Model Landfill
To increase the air space and therefore increase the useable life
of the landfill, trash is compacted into areas, called cells, that contain
only one day's trash. A sample cell’s measurements is 50 feet long
by 50 feet wide by 14 feet high (15.25m x 15.25m x 4.26m.) this cell
can hold 2,500 tons of waste and is compressed at 1,500 pounds per cubic
yard. ( Compression is done by heavy equipment, tractors, bulldozers,
rollers and graders, that go over the mound of trash several times.)
Once the cell is made, it is covered with six inches of soil and compacted
further. Cells are arranged in rows and layers of adjoining cells (lifts.)
Storm Water Drainage
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Model Landfill
To prevent leakage the landfill needs to be kept dry. This
can be done by either excluding liquids from the solid waste and by keeping
rainwater out of the landfill. Samples of the waste are tested for liquids
before entering the landfill by passing samples of the waste through standard
paint filters for 10 minutes, if no water is produced the waste is accepted.
To exclude rainwater, the landfill has a storm drainage system. The
system consists of plastic drainage pipes and storm liners that collect water
from areas of the landfill and channel it to drainage ditches surrounding
the landfill's base. The ditches are either concrete or gravel-lined and
carry water to collection ponds to the side of the landfill. In the collection
ponds, suspended soil particles are allowed to settle and the water is tested
for leachate chemicals. Once settling has occurred and the water has passed
tests, it is then pumped or allowed to flow off-site.
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Leachate Collection System Click Here to See the Model Landfill
Whatever water does escape into the landfill picks up contaminants
and can become acidic. To collect this contaminated water, leachate,
there is a system of pipes that transport it away from the landfill.
First, it runs into perforated pipes that run throughout the landfill.
These then drain into a leachate pipe, which carries leachate to a leachate
collection pond. Here it is tested for acceptable levels of various
chemicals (biological and chemical oxygen demands, organic chemicals, pH,
calcium, magnesium, iron, sulfate and chloride) and is allowed to settle.
After testing, the leachate must be treated like any other sewage/wastewater,
either on-site or off-site. Some landfills recirculate the leachate
and later treat it. This method reduces the volume of leachate from the landfill,
but increases the concentrations of contaminants in the leachate.
Leachate collection systems can clog up in less than a decade. They
fail in several known ways:
- they clog up from silt or mud;
- they can clog up because of growth of microorganisms
in the pipes;
- they can clog up because of a chemical reaction leading
to the precipitation of minerals in the pipes; or
- the pipes become weakened by chemical attack (acids,
solvents, oxidizing agents, or corrosion) and may then be crushed by the
tons of garbage piled on them.
Methane Collection System
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Model Landfill
Since bacteria in the landfill break down the trash in an anaerobic
manner landfill gas is a byproduct. This gas contains approximately
50 percent methane and 50 percent carbon dioxide with small amounts of
nitrogen, oxygen, and 94 different types of NMOC (non-methane organic compounds.)
This presents a hazard because the methane can explode and/or burn. So,
the landfill gas must be removed. To do this, a series of pipes are embedded
within the landfill to collect the gas. In some landfills, this gas is
vented or burned. More recently, it has been recognized that this landfill
gas represents a usable energy source. The methane can be extracted from
the gas and used as fuel. (green energy)
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Covering or Cap Click Here to See the Model Landfill
To provide for more space in the landfill the soil that is used to
cover the waste is interchanged with tarps or spray coverings of paper
or cement/paper emulsions. These emulsions can effectively cover
the trash, and take up only a quarter of an inch instead of 6 inches.
When a section of the landfill is finished, it is covered permanently with
a polyethylene cap (40 mil). The cap is then covered with a 2-foot layer
of compacted soil. The soil is then planted with vegetation to prevent erosion
of the soil by rainfall and wind. The vegetation consists of grass and kudzu.
No trees, shrubs or plants with deep penetrating roots are used so that
the plant roots do not contact the underlying trash and allow leachate out
of the landfill. If seepage occurs it looks black and bubbly and later
it stains the ground red. Leachate seepages are promptly repaired by excavating
the area around the seepage and filling it with well-compacted soil to
divert the flow of leachate back into the landfill.
Covers are vulnerable to attack from at least seven sources:
- Erosion by natural weathering (rain, hail, snow,
freeze-thaw cycles, and wind)
- Vegetation, such as shrubs and trees that continually
compete with grasses for available space, sending down roots that will
relentlessly seek to penetrate the cover;
- Burrowing or soil- dwelling mammals (woodchucks,
mice, moles, voles), reptiles (snakes, tortoises), insects (ants, beetles),
and worms will present constant threats to the integrity of the cover;
- Sunlight (if any of these other natural agents
should succeed in uncovering a portion of the umbrella) will dry out clay
(permitting cracks to develop), or destroy membrane liners through the
action of ultraviolet radiation;
- Subsidence--an uneven cave-in of the cap caused
by settling of wastes or organic decay of wastes, or by loss of liquids
from landfilled drums--can result in cracks in clay or tears in membrane
liners, or result in ponding on the surface, which can make a clay cap mushy
or can subject the cap to freeze-thaw pressures;
- Rubber tires, which "float" upward in a landfill;
and
- Human activities of many kinds.
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Groundwater Monitoring Click Here to See the Model Landfill
At many points surrounding the landfill are groundwater monitoring
stations. These are pipes that are sunk into the groundwater so water can
be sampled and tested for the presence of leachate chemicals. They measure
temperature of the groundwater to see if solid waste decomposes.
(An increase in groundwater temperature could indicate that leachate is
seeping into the groundwater.) Also pH is tested to see if it becomes acidic,
if so it may indicate seeping leachate.
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Other sites Click Here to See the Model Landfill
Materials that are not wanted or legally banned by the landfill are
disposed of in drop-off stations. A multi-material drop-off station
is used for tires, motor oil, lead-acid batteries and drywall. Some
of these materials can be recycled. In addition, there is a household
hazardous waste drop-off station for chemicals such as paints, and pesticides.
These chemicals are disposed by private companies. Some paints can be recycled
and some organic chemicals can be burned in incinerators or power plants.
A landfill is basically a bathtub in the ground. The liner creates a bathtub
in the ground. A bottom liner may be “one or more layers of clay or a
synthetic flexible membrane.” (Source: Environmental Research Foundation)
If the bottom liner fails, wastes will travel directly into the environment.
There are three classifications of liners:
Problems:
- Natural clay is often broken and cracked.
- The “very best landfill liners today are made of a
tough plastic film called high density polyethylene.” (Source:ERF) However,
many household chemicals can degrade this plastic, making it lose its
strength and become brittle.
- Plastic liners will have some leaks.
The U.S. has 3,091 active landfills and over 10,000 old municipal
landfills, according to the Environmental Protection Agency. Municipal
landfills and their leachate (water) and air emissions are extremely
harmful and dangerous. Municipal landfills can accept hazardous waste
under federal law. All landfills will eventually fail and leak into ground
and surface water. Plastics are not inert. State-of-the-art plastic (HDPE)
landfill liners (1/10 inch or 100 mils thick) and plastic pipes allow
chemicals and gases to pass through, become brittle, swell, and breakdown.
Old and new landfills are typically located next to large bodies of water,
making leakage detection extremely difficult. Federal and state governments
have allowed landfill operators to locate landfills next to water bodies
under the incorrect principle: Detection by monitoring wells can also be
very difficult at lined landfills.
The EPA released this statement; "There is good theoretical and
empirical evidence that the hazardous constituents that are placed in
land disposal facilities very likely will migrate from the facility
into the broader environment. This may occur several years, even many
decades, after placement of the waste in the facility, but data and scientific
prediction indicate that, in most cases, even with the application of
best available land disposal technology, it will occur eventually."
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