Evaluation of an Alternative Method of Leachate Collection System Design

Abstract

The current practice of leachate collection and removal system (LCRS) design for sanitary landfills has limitations because of the uncertainties associated with a key design parameter, leachate production rate. The traditional techniques for determining leachate generation are accurate only to within one order of magnitude. One of the drawbacks is the inability of these techniques to account for short-term fluctuations in leachate generation rate caused by heavy rainfall events or leachate recirculation events. This paper presents a rational method to account for fluctuations in leachate generation by incorporating a correction factor to leachate generation rates determined from traditional techniques. The correction factor known as the peak leachate factor (PLF) is developed from landfill lysimeter and pilot scale test cell studies. It is defined as the ratio between peak and average daily leachate generation rate, and is proposed to be used in conjunction with the output from a leachate generation model such as the hydrologic evaluation of landfill performance model to generate a design leachate generation rate. The potential of applying PLF in the design of a LCRS in full scale landfills is evaluated by studying the scale up possibility of the hydrological behavior of laboratory lysimeters to a field scale landfill test cell. The results demonstrated that the hydrologic behavior of the field test cell is similar to that of the lysimeters. The results indicated that various categories of landfill cells will require the adoption of PLFs depending on the type of waste landfilled and climatic conditions and operational characteristics of the landfills. PLF could be an important design parameter for LCRS in landfills cells, especially those operated with continuous leachate recirculation or located in tropical climates subjected to frequent high intensity rainfall events.