Drainage for sleeper wall at bottom of steep bank

[Kevilikeit]

Hi all,

First time poster looking for some advice. I've searched through the forums and a load of other sources and can't seem to find the same kind of application so thought I'd ask directly.

Last December as part of a bunch of work, I installed a path in my garden to avoid us having to walk in mud every morning. The path runs along the bottom of a steep bank that makes up one side of our garden. At the base of this bank I installed a single run of horizontal sleepers to retain the edge at the very bottom. At the time I was just trying to get something down in time for Christmas so these sleepers are currently only held by gravity.

IMG-20161221-WA0000

• Kevilikeit
• 26 Apr 2017

IMG-20161221-WA0001

• Kevilikeit
• 26 Apr 2017

DSC_0260

• Kevilikeit
• 26 Apr 2017

Now that the weathers improved I want to get this path and sleepers in more permanently. I was planning on relaying the sleepers on a small bed of dry mix and then putting 2inch square stakes behind them and securing with timberlok screws. The thing that I'm unsure of is what kind of drainage I need behind them if any.

From the pics you can see that the slope isn't huge the whole way but the point it's at its steepest and highest is right by the house. I don't really want seepage between the sleepers at this point as there will be a patio as well as the path which coukd well get covered with silt as a result. I could put full on perforated land drain and gravel behind but just don't know if it's overkill? From what I've found, ordinarily you wouldn't bother with drainage behind one horizontal row of sleepers but I'm just concerned about the amount of liquid that could come down from the bank?

Thanks in advance

 

[Johnpaul Manning]

Hi. In looking at your image there you will find that there would be no need for drainage behind the sleeper. If you are seeding grass or trees or plants on the bank you will that they will absorb a huge amount of moisture . remember that rain water when it hits the surface of the bank will seep vertical and is unlikely to flow down the bank. As a result the actual amount of water that could make its way in between the sleepers of the sleepers would be extremely little.

I think you are over thinking the situation but if you wanted to be safe you could put in a land drain but I think that is a bit of an over kill.

 

[r896neo]

Is the bank original ground? And does the land continue to slope up out of shot?
If it is virgin eaeth then you might be ok, if you have cut into it at all at the top or bottom you are at risk of a much higher volume of water as you may get groundwater seeping out of it.

For the simple lifespan of the sleepers its worth filling behind them with at least a few inches of gravel.

If this abuts paving then absolutely put in a geotextile and 4" of stone. This will at least mean any water that discharges will be clean.

If you have cut into the bank I would strongly suggest you consider a land drain while its easy to do at the construction stage.

 

[Kevilikeit]

The bank is original and it levels out behind the hedge you can see in the bottom pic. We have cut into the lower part where the sleepers are currently sitting. It used to slope completely to the bottom so we've cut out enough just to match with the height of the sleepers.

When you say 4" of stone do you mean depth vertically or horizontally?

This is why I'm debating now. I don't mind going through the trouble of installing a drain now if it saves me pulling them back out in years to come.

 

[r896neo]

Yes easier to do it now. By 4" I mean 4" horizontally, so a full ribbon of gravel up the back of the sleeper

 

[Kevilikeit]

Do you think the 2 inch square stakes behind the sleepers is the best way to fix them? I've thought about using rebar spiked into the ground into pre-drilled holes in the sleeper but feel like there's more room for adjustment with the stakes method.

Thanks for the help.

 

[r896neo]

Stakes is how i do it. Either will work