The sea is also used for waste. Rats - Landfills need to be sensitive to rat problems. Garbage is covered each night and in some cases covered with plastic sheeting. Some items may be restricted from a landfill. PCB's should be incinerated and certainly not in a land fill.
Radioactive material needs long-term storage as encased in glass.
Siting is a real problem as no one wants a toxic waste dump near their area. Another type is to make mounds separated by barriers. This is a better model where the water table is high. An extraordinary example of a landfill is the Freshkills land fill on Staten Island. Hazardous waste is sited above ground or in specially constructed dikes or trenches.