The Structure of Landfills

Abstract

Modern landfills are highly engineered waste containment facilities designed to isolate municipal solid waste from the surrounding environment, particularly groundwater. This paper details the essential components of a sanitary landfill structure. The design is a multi-layered system, starting with a base liner system, which is the primary barrier for contaminant migration. This typically consists of a composite liner, integrating a geomembrane (e.g., HDPE) with a low-permeability compacted clay layer or a geosynthetic clay liner (GCL). Directly above this is the leachate collection system, a network of perforated pipes within a high-permeability drainage layer designed to collect contaminated water (leachate) and remove it for treatment. The main body of the landfill comprises the compacted waste mass, which is placed in daily "cells." A landfill gas management system, often consisting of vertical wells or horizontal collectors, is integrated within the waste to capture methane and other gases produced during decomposition. Finally, upon closure, the landfill is sealed with a final cover system. This cap is also a multi-layered structure, designed to prevent water infiltration, secure the waste, and promote surface vegetation. The integrity of this complete structure is essential for ensuring long-term environmental protection.