Sealing and systems have to fulfill certain standards. One of the basic requirements for all technical facilities is the guaranteed functionality for 100 years.
According to the German Landfill Ordinance, the functionality of all technical elements in the top or bottom sealing system have to be guaranteed for at least 100 years.
Most of natural mineral materials (e.g. clay, quartz based sand) are per se inherently stable and can be used for sealing, capping or drainage elements without any analysis of their long-term stability and vulnerability to biological, mechanical or chemical agents.
Using mineral wastes to construct a sealing element several tests have to be conducted in advance of the installation to proof their long-term stability. In this test extreme environments are simulated (e.g. chemical reactions with very acidic leachates, pressure test simulating the superimposed load, long-term column experiments etc.). All tests have to be conducted by accredited laboratories, the results are evaluated by technical experts and the authority decides if the material can be applied.
For polymer elements the German Federal Institute for Research on Materials (BAM) analyses, evaluates, and certifies their quality. In order to simulate a time span of 100 years and to guarantee ta long-term stability, the materials are exposed to extreme environments as well. This includes e.g. the vulnerability to oxidation at higher temperatures (80 C) for 1 year, stability of surface structure of geomembrane after 10,000 h at 80 ° C, etc. When quality is approved, the polymer is certified and licensed to be used in sealing systems.
There are high investment cost for testing, ranging from 4 to 6-digits costs in Euro (mineral / polymer, respectively)
Evidence of success
These standards for the technical elements of sealing and capping systems are quite high. This guarantees a high level of environment protection and minimizes pollution risks for a long-term time scale, in this case for at least 100 years.
The analysis of the effects of biological, chemical or mechanical agents on mineral or polymer materials needs a high level of experience. The laboratory has to be equipped with special devices. The performance of the material after 100 years is not considered and remains unknown.
Potential for learning or transfer
Only by an adequate supervision the quality of the technical sealing and capping elements can be guaranteed. This minimized the threat for the environment and human health resulting from the deposition of waste on a landfill.
A defined quality of sealing elements should be applied for mineral and polymer materials used for the construction of a sealing or capping element. Particular for polymers, once tested, a long-term quality can be guaranteed. For polymers used for landfill sealing systems the CE mark of conformity can be enhanced in the context.
The use of quality controlled elements for encapsulating the landfill is especially important for hazardous-waste landfills.
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