Narrow Filter Drain

Narrow Filter Drains

The main types of Filter Drain, including Fin Drain, are illustrated  below. In essence they are trenches, often described as “high-tech” land drains, utilising different materials, such as Geotextiles and Geocomposites (Geogrid sandwiched between layers of Geotextile), enhancing filtration & allowing more rapid transference of water from the surface into traditional piped drainage. They are intended to eliminate, or reduce, the need for a granular backfill, reducing construction time and cost.  

The component parts are readily available from Cirrus.

Geocomposites can have permeable membranes to both faces, or one permeable and one impermeable face.

The Geogrid core can come in a range of thicknesses to cope with different flow requirements. 

Fin Drains are now commonly used to provide drainage at pavement edges to ensure that the sub-base and capping layers of a carriageway are not adversely affected by high groundwater levels.