Estimation of Municipal Solid Waste Landfill Settlement

The municipal solid waste landfill suffers from large postclosure settlement that occurs over an extended period of time. A large differential settlement may impair foundations, utilities, and other associated facilities constructed on top of a landfill. It may also lead to breakage of the geomembrane and damage of the cover system in a modern municipal solid waste landfill. The waste material exhibits heterogeneous engineering properties that vary over locations and time within a landfill. These factors, combined with the fact that a landfill is not fully saturated, render a traditional soil mechanics approach less attractive for settlement prediction. An empirical approach of expressing settlement rate using logarithmic and power relationships is commonly used in conjunction with an observational procedure. In this paper, validity of these functions is reexamined based on published settlement results from three landfill sites. A hyperbolic function is proposed as an improved tool to simulate the settlement-time relationships, as well as to detect final settlement. The relationships between the parameters of these empirical functions and water content are examined.