landfillLandfill: What Happens To Your Rubbish?

 

So you’ve separated your recycling from your general household waste and you’ve taken your wheelie bin down to the street ready for the waste disposal team to come and take it away. Afterwards, you wheel that bin back to the house and start filling it up again until the next time you need to take it to be emptied.

For many, that’s an end to it. After the rubbish lorries come and take the waste away, they don’t think about it anymore. And, to be fair, why would they? But have you ever considered what actually happens after your rubbish leaves you and wends its way to… wherever it goes?

Anything that can’t be recycled has to go somewhere, after all. That somewhere is the landfill. Landfills are large voids in the ground, usually created through quarrying work. They might also be part of a land reclamation scheme. This void can’t be dug out and the immediately filled with our rubbish. The land has to be prepared first, to prevent the decaying matter from leaching (too much) into it. If that happened, the bacteria and other nasties could find their way into water sources, and that could lead to health issues across the local area.

So, the land is lined with a number of different layers. The first is known as a regulating layer. This smooths the surface of the potentially stony or uneven quarry. Next a layer of clay is installed – this helps keep the area liquid proof. The next layer is a plastic liner, followed by geotextile (permeable fabric), then gravel, then another layer of geotextile. Throughout these layers, pipes and drained are laid. This entire process will need to be checked by the local authority to ensure that it meets their quality assurance

Once the area to be used as a landfill is ready, your waste can be tipped into it. The lorries that collect your rubbish is weekly or fortnightly and tipped into cells these are areas that have been sectioned off so that the landfill is filled evenly. It’s important that the area is filled in an even manner as a compactor then has to roll across it all, flattening it as much as possible. If the landfill was full of difficult to navigate lumps and bumps, the compactor – and its driver – would have a difficult time of it.

When each section has been flattened, it is covered with soil or matting. This stops any horrible smells from getting too bad (it’s all but impossible to get rid of them all, of course), and stops the waste from moving about.

Now, no matter how well compressed and no matter how well covered, some of that waste in those ‘cells’ is going to leak. That’s what the drains are for. The waste fluid (known as leachate) can’t be allowed to sit there forever – it has to be removed. It flows through the pipes into a pool where it is treated and then released back into the natural water courses. This is perfectly safe.

Waste liquid isn’t the only by-product of landfills. As the waste decomposes it creates methane gas (this is thanks to the lack of oxygen in the compressed cells). Methane is dangerous since it’s highly flammable, so again this needs to be dealt with. Some landfills use methane as natural energy, burning it to provide electricity. Others simply vent the methane safely into the air. 

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