In 1977, structural and maintenance management standards were established for final disposal sites. The
standards grouped the final disposal sites into three categories - controlled landfill, inert landfill, and isolated
landfill - and stipulated that waste must be safely disposed at landfill according to their properties. The
semi-aerobic landfill structure is employed as the structure for controlled landfill.
Harmful waste such as waste containing heavy metal and PCBs has the potential to adversely affect health
and the environment, and must be disposed of at isolated landfill sites. Non-harmful waste that has the
potential to pollute public water areas and underground water, or may affect the environment because of gas,
odor and/or pests must be disposed of at controlled landfill sites. Plastic waste, rubber debris, metal debris,
glass, ceramics and bricks that has little potential to cause environmental pollution can be disposed of at inert
landfill sites.