Modern landfills are very carefully managed to make sure they are environmentally friendly and are good neighbours to the land owners next door. This includes assessing all the environmental impacts. Here are some of them:
Making sure that rubbish is kept under control at all times is very important. This means locating landfills away from populated areas, and making sure rubbish doesn’t fly away in the wind. Even though Redvale is close to Auckland City, it still wins awards for the environment.
Landfills use heavy machinery to transport and compact the rubbish.
Rubbish usually contains rotting organic material and other materials that smell. Moving and compacting the rubbish has to be done to stop the smells being released.
There are also sprays used that stop bad odour coming from the landfill.
When rubbish is dumped at the landfill there is a risk that the wind will pick it up and blow it away. This problem needs to be managed carefully.
A modern landfill is designed to be a long term solution for storing waste. That means it needs to be in a place where there are no active earthquake faults that might crack the ground and release liquid (also called leachate) into the groundwater.
Rubbish is often light weight and easily blown away. A modern landfill needs to be protected from very strong winds.
Redvale landfill operations must be shut down when the wind blows above a certain speed.
Rain water seeps down through waste, making leachate. Leachate contains poisons and must be collected and managed. At Redvale, leachate is collected and turned to vapor. A special landfill liner acts as a barrier between the waste and the ground. This stops leachate seeping into the ground. The liner also channels the leachate to a collection point before being treated.
At Redvale, the landfill is covered with a thick layer of soil to reduce the amount of rain going into the rubbish. Rain that runs off the top of this soil layer is collected and treated.
- For more on leachate, watch this Waste Management video called The Leachate Boil up.
Landfill gas (LFG)
LFG is produced as organic waste breaks down inside the landfill. LFG has up to 60 percent methane, a dangerous greenhouse gas. At Redvale, a system of wells within the landfill collects LFG. The gas is piped to a treatment plant. The LFG is then used as fuel to run 12 generators. The generators make enough electricity to power up to 12,000 homes in the community.
• For more on LFG, watch this Waste Management video called Waste to Energy.
Monitoring and testing
Devices are used to monitor water in nearby ponds and streams. LFG and dust is also monitored. Redvale even has as an on-site weather station. Information from the monitoring devices is sent by coded signals on a computer based wireless system called telemetry.
Projects that disrupt the land need a rehabilitation plan. This plan will show how the land will be in the same or better condition when the landfill comes to the end of its life.