Membranes For Underdrain

When building an underdrain with our nero drainage cells, membrane is a crucial part of the system, not only in ensuring that rising groundwater that enters the nero cells is clean and high quality, but also in guaranteeing that your underdrain system will run efficiently and be equipped for longevity.

When it comes to choosing a membrane for your underdrain system, we provide a selection of recommended non-woven geotextile membranes. While Non-woven membranes have less load-bearing strength than woven membranes, they provide higher levels of water infiltration and still boast the ability to block soil and sediment from passing through them.

In an underdrain application, a geotextile membrane is laid out in the soil first, before the nero cells are placed on top and connected together. This is because groundwater will rise up towards the surface, so placing a layer of membrane beneath the cells means that water has to pass through the membrane before it reaches the cells. Think of the membrane as a sediment filter in this application. This can be seen in the diagram below, where the membrane is represented by the dotted red line.

Underdrain Diagram Nero Cell

What Is An Underdrain?

An underdrain is an underground drainage application that is used to capture rising groundwater and transport it to a surface drainage outlet. They are designed to keep roadsides dry and prevent groundwater from saturating the surface of the road as well as ditches and banks along the side of the road. Underdrains provide a range of benefits including separating clean spring water from road runoff water and cutting maintenance costs and time of wet roadsides.

In the case of nero cells, as groundwater rises up towards the surface, it will reach the bottom of the laid nero cells, which should be lined with a geotextile membrane. The membrane will allow water to enter the cells but not before it is cleaned and cleared of any sediment. Since the water is clean, it is able to travel along the underdrain and arrive at a drainage outlet at a faster rate, making for a more efficient underdrain system than one that would use gravel.