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Markeringsnet og geotekstiler - egnethed til markering mellem ren og forurenet jord 

Summary and conclusions

For the Danish Environmental Protection Agency Danish Geotechnical Institute have performed a literature study concerning the suitability of marking nets, geotextiles and geonets for the application as a separation between clean and contaminated soil.

Subsequently, Danish Technological Institute have carried out a test program on a selection of the three types of product and a product called warning net. Additionally they have made an assessment of substances in the materials, which might harm the environment.

The objectives of this task are to investigate, which possibly suitable products that are commercially available in Denmark, their properties, their price, and to which extent they meet the demands, that can be set up for the application in question.

When contaminated soil is being replaced in a site sometimes it is decided only to replace the upper (close to the terrain) part of the soil. Therefore it is important to mark the boundary between the newly added clean soil and the underlying contaminated soil. In order to clarify their visibility in the soil, their strength properties, their long-term resistance (service life) and other product properties different properties of the products have been investigated and evaluated.

The marking nets meet the demands best. All of them are clearly visible in the soil, as they are found in strong colours. Rainwater can seep through them without hindrance. They have an appropriate strength, and those, which are made from non pre-stretched threads, break in such a way, that they by digging will be drawn out to long thin threads, which are currently visible in the soil. During accelerated ageing of the products is has been shown that these properties can be expected to be - to a substantial degree - maintained for more than 50 years in the soil. Marking nets are made of polypropylene, to which antioxdants, UV stabilisers and/or pigments are added. These additives will not be extracted from the materials by seeping rainwater. Furthermore, as no contaminating fractions are being released during degradation of the materials in the soil, there is no risk of the release of any substances, which can contribute to additional contamination. Three of the tested marking nets break ductile. Moreover, one of them is the cheapest among all the investigated products.