SUSTAINABILITY: LANDFILLS

LANDFILLSTHE KINGDOM OF RUBBISH

SUSTAINABILITY UNIT

PRESENTATION 5

WHAT IS A LANDFILL?A landfill is a large hole in the ground into which we place all the rubbish left over from every day life.A landfill site is also known as a tip, dump, rubbish dump, garbage dump or dumping ground.

Historically, landfills have been the most common method of organised waste disposal and remain so in many places around the world.

All photos are depicting New Zealand landfills.

THE USESome landfills are used for waste management purposes, such as the temporary storage, consolidation and transfer, or processing of waste material (sorting, treatment, or recycling).

Kapiti Glass Recycling Depot

OLD LANDFILLSSociety has always needed places where they can dispose of their rubbish. In the modern society up until recently, landfills were usually known as dumps and were often not managed properly. Often old quarries, disused mines, gravel pits or marshlands, they had all kinds of solid refuse thrown in, over which occasionally a layer of dirt was spread to reduce smells, litter and vermin.

Black backed seagulls at Dunedin Green Island Landfill

PROBLEMSBecause these old landfills were not monitored, the surrounding ground water, streams and coastline were contaminated by the untreated leachate being discharged into the natural environment. Other problems that can occur are: • odours and litter• noise and traffic congestion• disease transmitted by pests• heavy metal contamination

Waste Disposal Method in Auckland

DIFFERENCES OLD/NEW LANDFILLSA modern landfill is expertly designed and constructed so that there are minimal adverse effects from the by-products of the landfill, on the environment, both during its construction and operation and after closure.

Landfill Compaction Hurunui District

LEACHATEThis is a black, poisonous liquid. As the waste breaks down and decomposes, it produces organic and inorganic chemicals which contaminate the water in the landfill. Rainwater enters the landfill while it is being operated and this filters down through the refuse, collecting these dangerous chemicals on the way. The more water entering the landfill, the more leachate is produced.

Image of leachate

collection wells

LANDFILL GASDecomposing refuse also produces gas. Anaerobic bacteria digest the large amounts of organic waste in the landfill and this produces the gas which is composed of:

a) Methaneb) Carbon dioxide

The rate it is produced, like leachate, depends on the amount of water in the landfill, how much the rubbish has been compacted and what material the finished landfill has been covered with.

This extraction well (the steel tube at right) captures landfill gas and feeds into a network

HOUSEHOLD WASTEFrom where does the landfill rubbish come from?This rubbish comes from household waste, from everyone’s homes and is all the things you put into your rubbish bag for the weekly refuse collection.It also includes the rubbish that is taken to the transfer station by people who have had a “cleanout day” at home, or have had some alterations or building done at home and there are pieces of wood and roofing iron left over.

Image shows the above ground location of the leachate sampling site, and the leachate pipe

OTHER TYPES OF WASTEOrganic waste - all the green waste including tree and shrub pruning, autumn leaves and grass clippings from public and private gardens.Construction and demolition waste - materials left over from building sites and from buildings that have been pulled down.Commercial waste - lots of office paper and cardboard.Industrial waste - from all the different types of factories.

WHAT HAPPENS AT THE LANDFILL?The landfill is designed to take many tonnes of rubbish but only a small section is used at once. The rubbish is compacted (squashed) and added to the “working face”. This is the part of the landfill that is currently being filled. At the end of the day or week depending on the landfill, the rubbish is covered over with a layer of clay to reduce litter, seagulls, odour and vermin.

A Landfill Compactor

THE END OF THE LANDFILL LIFEAs each cell or area of the landfill is finished it is sealed over with clay to help reduce the amount of rain entering. At the end of a landfill’s life the entire area is sealed with a layer of clay and then covered with top soil before being grassed over.

HOW LONG DOES A LANDFILL LAST?What Happens To It After It Is Closed? The average landfill is designed to last about 30 years. After closure it becomes playing fields, a golf course or other recreation area.

Omarunui Landfill Closed

BUYING A NEW LANDFILLIt takes many years to negotiate for new land for a landfill. The right piece of land has to be found and permission must be given by the regional council to use the land for this purpose. Also the people who live nearby must be kept informed and they have the right to object to having a landfill in their area.

Rotorua District Council - New Landfill

NIMBY SYNDROMEThis is called the NIMBY (Not In My Back Yard) Syndrome.Everyone wants to dispose of their rubbish, but no-one wants the landfill near their house. The owner of the landfill must follow guidelines for setting up the landfill that protects the environment and the community. This may include: • protection from noise and smells• safe access roads, pest control• trees to screen the landfill from the public