What Happens in a Landfill
What happens to your garbage in a landfill? If you are like most of us, you probably
haven't given it much thought.
In the Central Okanagan, garbage is taken to the Glenmore Landfill,
which is the only
active landfill in the
Central Okanagan. At the landfill the trucks are directed to the working face of the landfill to
dump their loads. The garbage is then evenly spread and compressed by a large compacter.
At the end of each day the working area, or cell, is covered with soil to reduce
litter, odours, and pests like birds.
Landfills are designed to minimize uptake of oxygen and water, keeping the garbage
as stable and environmentally safe as possible. Compaction and the soil cover keep
the air out and create anaerobic (no oxygen) conditions. This causes the garbage
to decompose very slowly; so slowly in fact, it is not unusual to find 50 year-old
newspapers you can still read.
Archaeology studies conducted in landfills have found recognizable ten year-old
romaine lettuce, 15 year-old hotdogs and even 20 year-old Kaiser buns. These studies
also noted about half of our garbage is leftover food and yard waste. These materials
cause the most problems in a landfill because of the moisture they add. If these
materials weren't put in landfills, odours and emissions, like methane gas and liquid
leachate, would be significantly reduced and landfill operations would be less costly.
(Ironically, kitchen and yard waste like grass, leaves and potato peels could easily
be composted in our backyards and turned into a rich soil amendment we could use
to enhance our gardens and lawns.)
The second largest component of our garbage is paper and cardboard. Other recyclables
found in landfills include glass, milk jugs, tin cans and aluminium. Rates of decomposition
for each of these vary, but it is estimated to take one million years for the plastic
and glass to decompose and several hundred years for aluminums and tin. These materials
could be easily be separated from garbage and recycled in the blue bag curbside
recycling program or taken to the nearest recycling depot.
Landfills have strict guidelines to follow and use state of the art technology.
For example, the Glenmore Landfill is lined with a high-density plastic (HDPE) liner
or low permeability clay to prevent soil contamination. It also has a leachate monitoring
system to prevent contamination of our groundwater, and more recently, introduced
methods for collecting methane gas.
Reducing, reusing, recycling, and composting may not completely eliminate the need
for landfills, but it does help save valuable space in our landfills for future
generations. It also keeps our landfills safer, and helps save precious tax dollars.
What is Landfill Leachate?
Solid waste typically contains some moisture when delivered to the landfill. Rain
and snow add more liquid and hasten biological decomposition. Liquids, which are
not absorbed or evaporated, flow outward and downward, transporting contaminants
from within the landfill. The action is much like water flowing through coffee grounds.
In the case of the landfill, the wear flowing through the waste is called leachate.
Because leachate may contain contaminants from the buried solid waste, it must be
prevented from going outside the landfill boundaries or down into the groundwater.
Through a complex combination of landfill liners, monitoring wells, piping, pumps
and capping of the landfill, leachate flow is restricted and captured.
Leachate collected at the
former Westside Landfill
and the active Glenmore Landfill is regularly tested to
ensure it falls within established parameters before it is discharged to the sanitary
sewer system.
A Leachate System Spill Response Plan is in place to ensure that potential risks
to the environment and public health and safety are minimized in the event of a
spill.
Landfill Gas
The decomposition process consumes oxygen and produces landfill gas. Landfill gas
in mainly a combination of carbon dioxide and methane. Methane is natural gas and
an energy source but is also a Greenhouse Gas. It is flammable and explosive in
certain concentrations so it must be controlled. Modern sanitary landfills are designed
and operated either to vent or use landfill gas. At landfill, gas is collected by
series of wells from a piping network and is burned in a flare.
Household Hazardous Waste in Landfills
Although hazardous waste is not allowed in the Glenmore landfill,
small quantities do get in. Typically, these are of such small quantities or volume
(when compared to the total of all waste received), they do little to change the
composition of either the leachate or the gas. However, the public should always
try to keep hazardous materials out of landfills.
Landfill Closure
After a landfill is closed, monitoring must be conducted for many years. The landfill
must be capped and the top layer of soil must support vegetation. Methane and Leachate
collection and monitoring systems must continue to operate.
Links to:
|