What happens to our rubbish - Landfill

Landfill

Picture of landfill site

Landfill sites are places where our rubbish is taken. When a landfill is created, it starts off as a huge hole in the ground, some of them used to be old quarries where sand or gravel was dug out. First the hole is lined with a thick black rubber liner so that no liquids from the decomposing rubbish can escape into the ground. Then a layer of tyres are placed at the bottom to protect this liner. A thick layer of soil is then put on top of the tyres and it is then ready to start receiving rubbish.

Picture of new landfill cell

At Heathfield Landfill site in Devon, which takes half of Devons rubbish, 150 lorries go there every day to unload rubbish. When the lorries first arrive at the landfill site they are weighed and the amount and type of waste is recorded. Waste is only emptied into one part of the site at a time, this is called a cell. The lorry unloads its rubbish and then a special vehicle called a compactor flattens the pile and drives over it to squeeze out the air and squash it down so we can get as much rubbish into the hole as possible. Compacters are very heavy, they weigh between 37-47 tonnes each and have special metal spiky wheels to grip on the rubbish as they drive over it.

Picture of compactor

At the end of each day the rubbish is covered with soil to prevent it from blowing around and wildlife, such as seagulls and crows, from eating it. It then rots down or decomposes, some rubbish can take hundreds of years to decompose. When one part of the site is full, it is covered with a thicker layer of soil (called a cap) which then has trees planted on or landscaped with grasses to create a wildlife area. The site will be looked after for many years. Closed landfill sites have been used as grassland or farmland.

Landfill sites have to be very carefully managed otherwise the rubbish could pollute both water and air. When rainwater falls onto the landfill site is drains through the rubbish collecting toxic and poisonous heavy metals such as mercury, zinc and lead, and bacteria and viruses from disposable nappies and chemicals on the way down. As food and garden waste rots in a landfill site, it produces a smelly dark liquid. This liquid and the contaminated rainwater produce a liquid called leachate.

Picture of leachate

If leachate were to get into rivers then it can kill all the fish and other animals that live there. So when landfill sites are being made, miles and miles of pipes are placed inside the rubbish to collect the leachate and take it to a place where it can be made safe to release into rivers without harming the wildlife.

Another thing that is produced when food and garden waste rot down in a landfill site is a gas called ‘methane’. We don’t want this methane going up into the atmosphere because it is a bad greenhouse gas that causes global warming, otherwise known as climate change. To stop this from happening, more special pipes are put into the rubbish as the landfill hole is being filled up, and then the methane and other gases are sucked out and taken to a place where they can be managed. In older landfill sites, these gases are burnt off, however, more modern sites use this gas to create energy. This is called Energy from Waste

For these reasons it is very important that we do not send our food and garden waste to landfill. It would be much better to compost this, either in your garden, or in some areas the council collects it from peoples homes.