A Guide To How Landfill Works

Most of us are utterly disconnected from our waste. We may use, reuse and recycle, but most of us don’t have an in-depth understanding of what happens to our waste. Their aim is to provide the final resting place for disposed waste that cannot be recovered. While they have offered a band-aid solution to the war on waste for over fifty years, it’s time we began confronting their issues. In facing up to the reality of landfills we need to begin by understanding how they work. 

The modern landfill design is a regulated pit in the ground that is divided into sections or cells. Each section is engineered in a way that ensures the compaction is maximised and the potential environmental hazards are minimised. It’s the cells that are filled with waste at the ‘end of its life cycle’ like commercial and industrial waste, construction and demolition materials and putrescible household waste (organic matter that decomposes and creates gases and unpleasant smells). Some landfills are licensed for only particular waste types, and others take all categories.

Landfills are not designed to break down waste: the sites are merely used for storage. This means that the waste decomposes slowly in an environment that is completely sealed with no access to oxygen. The bacteria created from the decomposition produces an abundance of methane gas. Methane gas is one of the most potent and powerful greenhouse gases – it’s highly flammable and dangerous when stored underground. 

The sites are designed intricately through a series of layers that each have a specific purpose. The bottom of a modern landfill is usually lined with dense and compacted clay in order to prevent liquids from permeating through to water systems. On top of this is a thick and high-density plastic liner that forms another protection layer. 

When the waste inside landfill decomposes, it produces liquids that combine with rain or snow that falls on top of the site. To collect these liquids, better known as leachate, perforated pipes are installed on top of the clay baseline and they are then funneled through to treatment facilities. 

In modern landfill systems, the methane generated from waste decomposition is collected in a layer of pipes that are placed above the solid waste layer. The methane is then stored and sold as Natural Gas, turned into electricity or burned as a source of energy.

The rubbish is compacted and covered up with a layer of dirt,  to contain odours and deter pests. Once a cell or section of the landfill is full, it is topped with a layer made of high-density plastic, then covered with soil and vegetation. It is then monitored for at least 30 years to ensure the area is free from contamination, and later on is turned back into public land including parks or open spaces. 

As Australians become more aware of their role in the war on waste, landfills are slowly reducing their capacity. We send around 20 million tonnes of waste to landfill each year, which is spread out between around 600 official landfill sites.

Despite the way they are greenwashed and glorified, there’s no dressing up the current state of landfill sites. While they offer a solution that fits into our current system, the future requires a circular approach that involves waste literacy for the general public and diversion initiatives. As they say, one man’s trash is another man’s treasure (or electricity).