What happens at a landfill site?

What happ

How we deal with mountains of household waste at landfills

Hills of household rubbish can be found in every country on our planet, along with flocks of gulls scavenging from them. Landfills are a common method of ditching our rubbish – something humans have been doing since 3000 BCE. However, it didn’t catch on in the UK until the 1800s. Before then, waste was left in the streets, which led to the spread of disease and poor environmental conditions.

Now known as ‘historic landfill sites’, waste-filled holes were first constructed without any consideration for the disastrous consequences to the surrounding environment. Over time some materials break down in mounds of rubbish, releasing a rotten stew called leachate. This gathering bin juice at the base of the landfill seeped through rock and entered natural underground water systems, known as aquifers. Carrying harmful chemicals and metal ions, the leachate was an environmental nightmare for wildlife and humans.

Having recognised the environmental threat leachate posed, ‘sanitary landfills’ were introduced in the early 1900s. They contain the toxic leachate by lining landfills with a series of protective layers. In order to stop the liquid from building up, collection pipes are installed to pump leachate from the landfill to tanks on the surface. The leachate is then sent to a water treatment facility.

These modern-day sanitary landfills are capable of holding a great deal of household waste. Spanning hundreds of thousands of square metres, some sites receive thousands of tons of material daily. In the UK one of the largest landfills, Packington, outside Birmingham, covered 1.5 square kilometres and had a 35 million ton capacity before its closure in 2015.

Landfills can take decades to fill, and once closed for business the sites are monitored for a further 30 years to ensure accumulating gas and leachate are being removed safety.

The many layers of a landfill

Much more than a hole in the ground, a landfill is made up of many layers

Click to expand (image credit: Future PLC)

This article was originally published in How It Works issue 128

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