Karup Airbase. Drainage of roof water to hybrid soakaways

Karup Airbase has numerous plastic soakaway units, and it has been something of a mystery as to why they have not worked better than they do. The initial theory was that the inefficiency was due to air pockets in the soakaways that stopped the water from entering, but on closer examination it was found that the geotextile surrounding the soakaway units was covered by a 2-3 mm layer of dirt on the inside, stopping the water from seeping from the soil.

Others have had similar experiences, namely that water cannot penetrate the geotextile - even when it is brand new.

To avoid using geotextile on soakaway units, engineer Christian Ramsgaard from the Karup Air Base has developed a hybrid soakaway that combines soakaway units with conventional gravel (that cannot penetrate the surface of the soakaway units). See more at www.hybridfaskiner.dk (in Danish).