Landfill Engineering

Landfill engineering is the design and operation of sanitary landfills that isolate solid waste from the environment.

Definition

An engineered facility for the disposal of solid waste on land, designed with containment, leachate collection, and gas management to isolate waste and minimize harm to air, water, and soil.

Scope

This topic covers the engineering of modern sanitary landfills. It addresses the containment systems that prevent pollution, including liners and leachate collection, the management of landfill gas generated by anaerobic decomposition, daily and final cover, and the long-term care of closed sites. The decomposition processes that produce leachate and gas connect the engineering to the underlying biochemistry of buried waste.

Core questions

• How do liner and leachate systems contain landfill pollution?
• What is landfill gas and how is it managed?
• How does waste decompose within a landfill?
• What long-term care do closed landfills require?

Key theories

Containment by liners and leachate collection

Engineered liners beneath the waste and overlying drainage layers capture leachate, the contaminated liquid formed as water percolates through refuse, preventing it from reaching groundwater.

Anaerobic decomposition and landfill gas

Buried organic waste decomposes anaerobically to produce landfill gas rich in methane and carbon dioxide, which must be collected and either flared or used for energy to manage hazards and emissions.

Clinical relevance

Well-engineered landfills protect groundwater and air by containing leachate and capturing methane; understanding their containment and decomposition processes is essential to preventing pollution from waste disposal.

Evidence & guidelines

Landfill design commonly follows regulatory requirements for liners, leachate and gas management, and closure; these are described here to explain how landfills are engineered rather than as prescriptive rules.

History

Open dumps gave way to engineered sanitary landfills in the mid-twentieth century, and stricter regulation later mandated composite liners, leachate and gas collection, and long-term post-closure care.

Seminal works

• tchobanoglous1993
• qian2002
• davis2008

Frequently asked questions

What is leachate and why is it a concern?

Leachate is the contaminated liquid that forms when water percolates through buried waste, picking up dissolved and suspended pollutants; if not collected and treated, it can migrate and contaminate groundwater, which is why landfills use liners and drainage systems.

Why does a landfill produce gas?

Microorganisms break down organic waste without oxygen inside a landfill, generating landfill gas that is mostly methane and carbon dioxide; this gas is collected and flared or used for energy because methane is flammable and a potent greenhouse gas.