the diagram illustrates the biological clock of a morden landfill used to decompose household waste.
It can be seen that there are a total of three main stages in the life cycle of a landfill: the construction; the usage and the closure.
firstly a huge hole is dugged by men above a bed of natural rock. Once the hole has been bugged, it is lined with a thick layer of clay, followed up by a thin layer of synthetic materials in order to minimize the lackage of toxic waste substances into the surrounding earth. Drainage pipes and a drainage of tank are also set up to get rid of toxic waste liquids from the bottom of the landfill.
when the man-made landfill has been build, household wastes will be filled in it. During the disposal process, toxic waste liquids will dive into the bottom where they are trapped in the drainage tank and then removed through drainage pipes to prevent the accumulation of toxic gasses. Once the landfill is fully filled up, it is covered with a layer of clay. As the wastes degrade over time, it then will be emitted to the landfill.