Estimate of Landfill Settlements Due to Mechanical and Decompositional Processes

Approximate closed form solutions are developed for estimating the mechanical and decomposition settlement of landfills. The mechanical settlements are the immediate (primary) settlement and long term creep. The decomposition settlements are generated by mass loss and gas generation. Based on the approximate solution, the decomposition settlement can constitute a significant portion of the total settlement and can be in the same order as the mechanical settlements. Settlement remaining after landfill closure depends on the decomposition environment during filling. For an average decomposition environment, postoperation settlement can still be significant 20 years after completion of filling.