Geotextiles
Geotextiles are fabrics that have the ability to provide a permeable soil barrier for use in geotechnical applications. There are many different types and forms of geotextiles used throughout the world; yet in general fall into one of three catergories;
Each different category of geotextile can be made of many different materials, yet most of the time made of some sort of polypropylene or polyester.
Geosynthetic Clay Liners
Geosynthetic clay liners come in many forms and there are many companies which make different products. Basically a geosynthetic clay liner is a layer of clay bounded by two layers geotextiles. These liners are used in landfills to provide a non permeable boundary to protect the environment from leakage of harmful materials.
The picture above shows a geosynthetic clay liner produced by one company, displaying the general three layer construction.
Landfill Lining System
There are many different ways of lining landfills, each with the same goals in mind;
- Provide boundary from environment
- Allow drainage of leachate
- Long time storage
A typical lining system is shown below;
Australian Standards also outline regulations in the way waste is stored depending on the type being stored. The following diagram shows the classes of wastes outlined by Australian Standards.
Recent Landfill Operations
Recently an upgrade of the Red Hill Waste Management Facility, Red Hill, Western Australia was undertaken. This facility has been upgraded to hold both class III and class IV waste; the class III storage cell holds approximately 1.1 million cubic metres of commercial and municipal waste and is engineered with geosynthetic clay liner and 2mm High Density Polyethylene (HDPE) liner. The geosynethetic clay liner used in the construction is made of Kaolinitic clay found from the site. The class IV cell storage is more harmful and therefore higher safety is required for the construction; the Red Hill Facility is built using two lining systems each with leachate collection systems, geosynthetic clay liners and HDPE. This storage is also highly controlled and monitored to alert any signs of leachate leaking through the two layers. The following diagram shows this situation.
As seen above the layers allow for leachate to be monitored through the coarse material layer.
References
1. Geofabrics, Australasia, http://www.clay-liner.com/wawcs0131042/idDetails=172/Our-GCL%27S-are-manufactured-to-the-highest-international-standards.html, viewed 08/09/2009
2. Landfill Waste Classification and Waste Definitions 1996, Department of Environment, http://www.dec.wa.gov.au/component/option,com_docman/gid,1316/task,doc_download/, viewed 10/09/2009
3. The Eastern Metropolitan Regional Council, www.emrc.org.au/news-pg-617.asp, viewed 10/09/2009
