Mining landfills can be a complicated undertaking, depending on the landfill. Many agree however, that it can be worth the effort in many cases. Read on to see what is involved in mining landfills and why you should care about it.
What Is Mining Landfills?
Mining landfills is the arduous task of digging into an old filled landfill to remove and separate the materials within it. Typically, this would involve using standard excavating and processing equipment. Soil excavators dig into the ground and a trommel separates the large materials such as appliances, furniture and old tires.
Mining landfills is actually broken down into several smaller jobs. After the landfill is excavated, the materials would be separated into soil, combustible material, recyclable material and other materials.
Breaking it Down
Some say that as much as 65 percent of landfill material is soil. That still leaves another 45 percent of materials to deal with.
- Combustible Materials: Combustible material is material that can be used as refuse derived fuel or RDF. For example, wood from a construction landfill can be mined and burned as fuel in a power plant. Combustible materials include plastic, wood, paper, rubber, foam and even clothing.
- Recyclable Materials: Recyclable material is material that is reused. Scrap metals can be salvaged while mining landfills and sent off to recycling plants. Other recyclable materials include glass, iron and aluminum. Plastics can also be recycled.
- Toxic Materials: Toxic material can also be removed while mining landfills. This allows them to be properly disposed of and reduces the chances of them leaching into the soil and water table.
- Residual Materials: Residual materials are materials that do not fit into the other categories. These materials are put back into the landfill, but since so much was removed by the process of mining, there is far more room than there was previously. The residual materials can be safely dealt with so they can decompose instead of being a problem forever.
A Major Task
Mining landfills can be a major task in some cases. Municipal landfills that were made before regulations required them to have liners may already have a problem with leachate.
Leachate is the contaminated liquid that drains from the landfill when rainwater and other precipitation percolates through the waste materials causing it to break down. This process causes more liquid to form, all of which is possibly toxic from the materials in the landfill as well as the mold and fungus that grow in it. Mining landfills can cause this leachate to pose a health risk if the materials have not fully broken down.
Yet in other cases, such as construction landfills, the process of mining landfills can be relatively easy. Construction landfills are primarily filled with wood, drywall and scrap metal. This material is easily reclaimed and used for other purposes, eliminating the need for the landfill.
Benefits vs. Costs
Fortunately, if done properly, mining landfills can be an ideal way to keep toxic leachate from seeping into the surrounding soil and groundwater. Mining landfills can have other benefits as well. It can allow wasted land to be recovered and used again. At the same time, it has the potential to improve the value of land surrounding the old landfill. Perhaps the biggest benefit is that mining landfills has the potential to minimize future environmental problems caused by contamination within the landfill.
Unfortunately, in the United States it is thought that the cost outweighs the benefits. While mining landfills is considered to be a possibility in the future, it isn't considered reasonable now. The technology is available. The cost is simply prohibitive according to experts
Other countries feel just the opposite is true. More research will need to be done. However, one thing is certain, there is no shortage of research material. To learn more you can visit the Global Landfill Mining homepage.