Wastes are disposed of away from the city in sanitary landfills. The waste is first spread in layers and then is compacted tightly so that its volume is reduced. The waste is then covered by soil and subjected to bacterial decomposition. Sanitary landfills are useful as the wastes are not attacked by rodents or insects. One precaution which needs to be taken is that landfills should not be located in areas that have high underground water levels as they may get polluted.
Also, Read What is Soil Pollution?