Settlement and Bearing Capacity Problems Associated with Sanitary Landfills
Sanitary landfills are a common method of waste disposal in densely populated areas. The average unit weight of the refuse in a compacted state can vary between 5-10 kN/m^3 (32-64 lb/ft^3). In a typical city in the United States with a population of one million, approximately 3.8 x 10^6 m^3 (134 x 10^6 ft^3) of compacted landfill material is generated per year. As property values continue to rise in these areas, there is a growing temptation to construct structures over sanitary landfills. However, this can pose several problems. Visual site inspections may not always be sufficient to detect the presence of an old sanitary landfill. Construction of foundations over these landfills can be problematic due to the presence of poisonous gases, such as methane, excessive settlement, and low inherent bearing capacity. Settlement is a major concern when building over a sanitary landfill. The weight of the structure can cause the underlying waste to compress, leading to differential settlement. This can result in uneven floors, cracked walls, and other structural issues. Additionally, settlement can also affect the stability of nearby structures, posing a risk to public safety. Another issue is the bearing capacity of the landfill. The waste material in a sanitary landfill is not uniformly compacted, leading to variations in its strength and load-bearing capacity. This can make it difficult to determine the appropriate foundation design for a structure built over a landfill. In some cases, additional measures, such as soil stabilization techniques, may be required to ensure the stability and safety of the structure. In conclusion, constructing structures over sanitary landfills can be challenging due to settlement and bearing capacity problems. It is crucial to thoroughly assess the site and consider the potential risks associated with building over a landfill. Proper foundation design and construction techniques, along with regular monitoring, are essential to mitigate these issues and ensure the long-term stability and safety of the structure.