How to stop sand leaking from retaining wall?

[MaraBee]

Hello.

I have a long standing problem with sand leaking from underneath my retaining wall. 

My pavers get covered in sand, weeds keep popping up and our floor drains get sand bogged.

I have searched the internet for solutions - but no luck!

Any thoughts? Thanks

 

[EricL]

Hello @MaraBee 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your retaining wall.

Would it be possible for you to take a level photo of the gap at the bottom of your retaining wall. This will allow us to see and assess how big the gap is and if it can be dug out. I propose digging out the sand and see if you can get to solid soil. If you can, odds are only the very fine sand is being drained down the retaining wall. It might be possible to cover up the gap with concrete, this would technically stop the sand from coming out. 

However, if sand continues to come out and shows no sign of stopping it might be necessary to disassemble your retaining wall and fix the bottom part properly. 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendation.

If you need further assistance, please let us know.

Eric

[MaraBee]

Hi Eric 

Thanks for your suggestion.

Dissembling & reassembling the retaining wall  might not be practical in this situation. 

The wall is approx. 19m with each segment being approx. 1.1m.

Perhaps if I mixed the cement with bondcrete that would help hold the sand.

Here are a couple of extra photos.

I look forward to anyone else with ideas.

Cheers 

  

 

[EricL]

Hello @MaraBee 

Thank you for posting those extra photos. Your initial exploration of the sandy bottom of your retaining wall looks very promising. It appears that you can dig deeper into the gap. Your suggestion of using BondCrete is actually very good as it will help the concrete bind to the surface of the paver and retaining wall. I propose digging deeper to see how far you can go, the deeper the cavity you can dig out the larger amount of concrete you can put in.  

My best advice is to clear out as much of the sand as possible and to make sure the concrete patch covers every possible exit hole at the bottom of your retaining wall. Once the concrete cures you can then paint it in the same colour as the retaining wall.

If you need further assistance, please let us know.

Eric

[Dave-1]

Good Evening @MaraBee 

Having sand or soil coming from somewhere is a pain, tho good part (not much of one but its better then nothing) is that it should show up by a drop in the sand/soil level from behind the retaining wall.

If you gently remove the grass/weeds/mulch that is just above the wall, can you see a dip in the material? Or remove all the ground cover and then give the bed a decent hose and take note of when the water/sand starts seeping out. 

If you can find the dip or see where the sand is coming through the wall then I would suggest to dig down behind the wall to find the point where it is traveling through. If the sand is leaking underneath the retaining wall, you could also remove the first row of pavers and take note where the sand rises/comes through.

Dave

[Nailbag]

Hi @MaraBee 

1. If the sand is overflowing from the top, then your will need to address the issues from the other side of the fence. 

2. If it's from between each sleeper level, then this will be more difficult to retain from your side. It really needs to be sealed from the rear. But you could try cleaning out the grooves and applying a very thing coat of bitumen membraine. But This will be an obvious mismatch in colour requiring you to use a masonry exterior paint to covert the entire wall. But this woulds solve the issue.

3. If it's an issue from the bottom. Then I would dig out the sand about 200mm and fill with concrete.

Nailbag

[Dave-1]

Morning @MaraBee 

Thank you for those extra photos, they really show where the sand is coming out (which is good) and also the tightness of the space you have to work with.

I am presuming that there is just sand behind the wall in this instance (cross fingers)

-You could get a piece of PVC pipe maybe 25-30mm diameter.

-A funnel (with the nozzel to fit inside that pvc pipe.)

-The bond crete or other concrete powder.

-length of timber dowel that fits mostly inside the pvc pipe.

Using the PVC pipe stand it up on the sand at the rear of the retaining wall,

Then run your hose down the inside of the pipe (without a nozzel)

Turn tap on not super hard, you are wanting to eat the sand/soil away slowish.

As the sand/soil and water come out the pipe will easily go lower, continue until you have reached the base of the wall or even a little lower. 

Pour a little of the concrete powder (dry) down the hole, then use a length of timber dowel to push it down, doing it in small steps/amounts. Lift the pvc pipe up as you push more concrete down so it back fills the area that the water has hollowed out. I would only do say the bottom 2 planks. Maybe 3 to start with and see if it changes the amount of sand coming out. Then you can work your way along if more is needed.

Dave

[MaraBee]

Hi Dave. 

Thanks for this advice.

My brother suggested something similar and might be the better/longer term solution.

Even if a bit harder to do.

Cheers.

[MaraBee]

Hi Nailbag.

No sand overflowing from the top. Just a gradual sinking in some places - been watching it for about 9 years.

The dig out and replace with concrete might be the most achievable for me to do.

And I can tackle one segment at a time.

Thanks for the advice.

[MaraBee]

Hi EricL, Dave-1 and Nailbag.

Just thought I'd give an update on this project.

1. Dug out the weeds + sand to the edge + depth of the pavers to underneath + the width of the wall deep.

2. Sprayed with Brunnings path weed killer.

3. Filled the cavity with Westbuild Cream Dry Mix Mortar + Bondcrete.

Three sections of the retaining wall took me just over 3 hours.

Thanks for your thoughts. 👍