Settlement of a bioreactor landfill during filling operations

The knowledge of the rate and amount of settlement is important for effective design and operation of sanitary landfills. Accurate knowledge of settlement would allow estimation of air space, planning of construction sequence, design of both intermediate and final covers as well as planning for expansions. It is also essential for the design of piping systems used for the delivery of re-circulated leachate and landfill gas recovery, if the landfill is operated as a bioreactor. Though the majority of settlement takes after landfill closure over a number of years, considerable amount occurs during the filling and construction stages, which usually goes unnoticed. In the Calgary biocell, which is a bioreactor landfill, real-time waste settlement data was collected during the filling of the cell. The settlement trend follows the waste filling operation. The data was analyzed and the average unit weight of the waste matrix and the compression index were calculated. These two parameters can be used in mathematical models to predict early stage waste settlement.