whenever you throw away your rubbish do
you ever wonder where it goes what
happens to it and the effect this can
have on the environment
the answer is that everything that has
not been recycled or reused ends up in a
landfill site what do you think this
means
if you think that a landfill is an open
hole in the ground where we buried a
rubbish you'd be wrong in fact it is a
carefully designed structure built into
or on top of the ground to store your
rubbish
in such a way that it will be isolated
from groundwater our fresh water supply
will be kept dry preventing leaking into
this groundwater and will not come into
contact with the air causing horrible
smells
this isolation is achieved with a bottom
liner typically made from very thick pvc
and a daily covering of soil
however in many countries open rubbish
tips still exist causing environmental
and health problems
if our rubbish is isolated from the
surrounding environment it doesn't
decompose
landfill sites are not like a compost
pile where the purpose is to bury
rubbish in such a way that it will
decompose quickly rather landfill sites
are simply a way that we cope with the
vast amounts of rubbish that we produce
let's now take a look at the parts that
make up of the landfill cell and how
these cells make up organized landfill
sites
groundwater has to be protected from
chemicals found in our waste and so
compacted clay is placed on top to act
as a physical barrier
on top of this is a very thick
waterproof plastic liner
this stops water that contains waste
chemicals called leachate from
contaminating this groundwater
a geotextile mat
typically made from polypropylene or
polyesters are like a woven fabric
and this too prevents plastic sheeting
from being damaged by the sharp gravel
layer as the rubbish on top is compacted
the gravel layer on top of the
geotextile map filters large pieces of
debris allowing only water through
this improves the drainage of the
landfill cell
the gravel layer is connected to a
leachate pipe
the leachate is collected through pipes
where it goes into a leachate pond
this leachate can't be used as drinking
water and needs to be treated like
sewage before it can be removed from the
site this must continue even when a
landfill site is full
a drainage layer and a soil layer
prevent firming from entering landfill
cells
finally on top of the landfill cells old
new is where buried rubbish is compacted
by heavy diggers and machinery
bacteria in landfill break down the
trash under anaerobic conditions meaning
in the absence of oxygen and so a
byproduct of this breakdown is landfill
gas
this presents a hazard because this gas
contains methane which could explode
therefore it has to 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
what do you think might be a better use
for this gas pause the video and
continue when you're ready
if you said that the methane in the
landfill gas could be used as an energy
source you'd be right
this means it could be collected and
burned in boilers to generate
electricity in summary a landfill is
carefully constructed and allows waste
only to be stored
it may never decompose and is not really
a viable solution for dealing with waste
in addition extensive monitoring is
required to ensure that no leachate
escapes into the groundwater
this has to happen even once a landfill
is no longer in use
there aren't really any upsides to
landfill although the gas produced can
be collected and burnt as a fuel
it can also cause explosions if not
vented properly so we need ways to
recycle reuse
you