This was a landscaping project where some ancient lakes had been dug out and de-silted.

A significant amount of soil and silt was extracted from the lakes using mechanical excavators. A number of islands were constructed in the lakes using the soil and silt which had been removed from the lake beds.

Wallbarn was asked to supply geotextile fabrics to act as a retainer, to prevent the newly extracted soil form slumping back into the lake once it was filled with water.

It was essential that a permeable, strong but flexible material was used, as the very wet soil which had been piled up needed to be able to drain away, but also that soil which had been built up was very heavy and unstable and needed to be held in place without slumping.

Wallbarn recommended a high tenacity virgin fibre polypropylene geotextile – 170 grammes per m2 in weight.
The fabric was in roll sizes 2 metres wide, which made it easier to handle in the difficult conditions. It was rollled out and pleated where necessary around corners or difficult areas such as tree roots.

Due to the fish and bird life in the lakes, it was important that nothing sharp or dangerous, and nothing which may give off toxic discharge, was used to fix the fabric into place. Therefore it was secured in place using biodegradeable stakes (made form vegetable fibre). These stakes would hold the geotextile in place for up to a period opf nine months before degrading into the soil.

The whole island was covered with the fabric and the lake was allowed to fill up normally.