Drainage Pits, Channels & Pipe behind wall

Ag pipe, drainage gravel and bidum behid retaining wall.

In any landscape project, the drainage of an area is critical to the overall success of the job and here is a range of all those ‘bits and pieces’ to help you complete your project, Ag Pipe, storm water pits, drains, channels and grates for keeping water moving to the right areas of your land, pegs, weed mat, geofabric, black plastic and more. Many of these products can be used in conjunction with the drainage system you install behind a retaining wall and will ensure the most successful outcome. If you need advice for these finishing touches see our DIY videos and DIY Guides, or ring and speak to one of our friendly and knowledgeable sales team.

How important is drainage? How important are drainage pits, channels and pipes?

The short and simple answer is … Drainage Pits, Channels & Pipes are EXTREMELY IMPORTANT!

Whenever we build a wall, be it retaining a stable “cut” in the land or holding back fill, the effort we put into the drainage behind the wall is crucial to the success of the wall itself. By erecting a vertical or near vertical structure at a point where the land changes in height, there is the potential for it to become a “Dam Wall”. If this occurs, water will be trapped behind the wall where it builds up pressure on the supports and in some cases result in the wall failing.

In any DIY video produced, there will always be a strong emphasis on the drainage material used behind the wall being built. The whole reason for the drainage is so that during heavy rain or extended wet periods, that water does NOT collect behind the wall and has a way to “escape” This is done by placing an Ag Pipe at the base of the wall (behind it) and then covering this with Drainage Gravel. The quantity of gravel used will vary depending on the height of the wall and the amount of water runoff expected but as a general rule, the more gravel used the better.

One thing to avoid at all costs, is lining the back of the retaining wall with plastic as this will indeed result in water being held behind the wall. If you are concerned about dirt seeping through the joints in the wall, then you can line the wall with a filter cloth called Geofabric (Bidim) as this will let the clean water drain through and hold back the dirt.

When designing your wall, check the manufacturers’ brochures or the DIY videos on our website to get the full story on the importance of drainage.

Installing Drainage Systems, Drainage Pits, Channels & Pipes