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Bleed Green
08-27-2009, 12:08 PM
The ground behind the retaining wall in my front yard is sinking and I am not sure how to remedy it. I have tried filling it three different times and it just keeps sinking out. I am not sure why it is doing this. When the company installed the wall they did have to move it back a little bit because they put it in the wrong place. I am wondering if having to move the wall had something to do with it sinking out like it is. What would you guys suggest I do to try to fill it and get it to stay solid behind the wall?
Thanks in advance.

Summit L & D
08-27-2009, 01:39 PM
Pictures, please.

Bleed Green
08-27-2009, 03:16 PM
what is the easiest way to go about posting a picture?

tthomass
08-27-2009, 04:45 PM
Save it to your computer, click on "post reply" and click one "manage attachments"

DVS Hardscaper
08-27-2009, 06:23 PM
Respectfully, I don't think a picture is needed.

The ground has settled / sunk for one of two reasons:

a) The area that sunk was disturbed and/or imported and not compacted.

b) Water is somehow collecting behind the wall. Could be surface water. Could be the downspouts on the house are discharging water thats finding it's way behind the wall. Could be a leaking water main.


It's one of these two scenerios. Water or uncompacted soils.

I'll go as far to say it's most likey uncompacted soil.




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andyslawncare
08-27-2009, 07:08 PM
Does your wall have drainage behind it? How tall is the wall? What did they use for the base and how deep was the base? Pictures would be helpful. Sounds like they didn't install drainage, didn't make the base deep enough or didn't use the right material, or didn't compact the soil good enough.

Bleed Green
08-27-2009, 07:14 PM
There is a storm sewer line that runs under where part of the wall is. There is some mud in the pipe now that I look at it again. Maybe the pipe has a fracture in it and the mud is sinking down into the pipe? I wouldn't think that would be causing it to sink all the way along the wall though like it is.
If there is a broken pipe below where the wall is, what is the best way to fix it? just dig down, patch the pipe and then rebackfill the wall i guess?

DVS Hardscaper
08-27-2009, 07:17 PM
Improper drainage would cause a wall to blow out.

Bleed Green
08-27-2009, 07:22 PM
I was thinking when they had to move the wall back a foot or so they got off the footing and were pissed that they had to move the whole wall anyway, so they didn't care and now the weight and the everything was making the wall settle. I could be wrong, just a theory.

DVS Hardscaper
08-27-2009, 07:23 PM
There is a storm sewer line that runs under where part of the wall is. There is some mud in the pipe now that I look at it again. Maybe the pipe has a fracture in it and the mud is sinking down into the pipe? I wouldn't think that would be causing it to sink all the way along the wall though like it is.
If there is a broken pipe below where the wall is, what is the best way to fix it? just dig down, patch the pipe and then rebackfill the wall i guess?


I still think your problem is derived from improper / lack of compaction. If a line is leaking, you have to dig around it, find the leak, and repair.

In our area there is a big, new retaining wall in a new housing development. Built by a multi-million dollar company that mose nothing but big, monster walls. Well a water main that feeds the community sprung a leak and caused the wall to fail. Not sure why, but the developer is trying to get the wall contractor to accept responsibility.



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Bleed Green
08-27-2009, 07:23 PM
i guess the only way to find out what is going wrong is to dig down there and look and see what I can find.

DVS Hardscaper
08-27-2009, 07:27 PM
I was thinking when they had to move the wall back a foot or so they got off the footing and were pissed that they had to move the whole wall anyway, so they didn't care and now the weight and the everything was making the wall settle. I could be wrong, just a theory.


Your opening post said the ground behind the wall is settling.

Now you mentioned the "wall settled".


2 different things, amigo!



If the wall settled, thats from either:

a) Improper compaction / materials of the wall's aggregate base.

b) Installing a base on a wet subgrade.

Bleed Green
08-27-2009, 08:14 PM
The problem is the dirt behind the wall is settling. Disregard that theory. I was just saying if the wall got off the footing than that may be what is causing the settling behind the wall possibly.
That is the main problem though, I am not sure what is going on here, but there is something not right cause I have had to fill in 3 times behind the wall where they were sink holes forming.

Bru75
08-27-2009, 10:48 PM
Sounds like a lack of compaction in the fill to me. If the wall is off the footing then the wall itself should be settling (or falling over).

Bleed Green
08-27-2009, 11:31 PM
Sounds like a lack of compaction in the fill to me. If the wall is off the footing then the wall itself should be settling (or falling over).

ya that is true. Just try to compact the fill behind the wall better you guys think?

Bru75
08-28-2009, 07:43 PM
ya that is true. Just try to compact the fill behind the wall better you guys think?

If you know the drainage behind the wall is good, I'd just keep filling as it settles.
If the drainage isn't there or if you don't know for sure you might be in for some digging.
Sorry if I missed it, but how tall is this wall?

Bleed Green
09-01-2009, 11:06 PM
its about 5 courses of block high. I am guessing that the drainage is good, otherwise I would think there would be dirt coming out from between the blocks in the wall and under the wall at the base where it meets the ground.

CF1128
09-02-2009, 08:33 PM
No disrespect intended, but just filling in behind is not the answer.
Many things can cause a sink hole, we fix them all the time up here in N.H.
It could be a rotting tree, debris from the construction of the house etc...
DVS is correct, it is a compaction issue, but you need to find out if it is a sink hole or bad drainage. Or one caused by the other.
We have had to go down 20 feet multiple times to fix a sink hole, but it sounds like this is a recent problem, so I would think it is a drainage issue and a poor base.
Is it a load bearing wall? What type of anchor system was used?
We usually double+ an inch or two of whatever the manufacturer suggests for a base, sometimes more up to 18 inches depending on water table up here.But we have major frost issues, and six inches does not cut it.
We have never had a "wall settle issue". If the prep work is done properly, and the first course is perfect, nothing should settle, if compaction and the base was done right. Unless you are retaining water.
Just my opinion.
Good luck!

CF1128
09-02-2009, 08:41 PM
Don't get me wrong, I know things settle, I mean in a major retaining wall, with the correct prep and anchor system, the "settle" should not be a major issue, it is not a paver walkway or patio is my point.

Bru75
09-03-2009, 12:17 AM
No disrespect intended, but just filling in behind is not the answer.
Many things can cause a sink hole, we fix them all the time up here in N.H.
It could be a rotting tree, debris from the construction of the house etc...
DVS is correct, it is a compaction issue, but you need to find out if it is a sink hole or bad drainage. Or one caused by the other.
We have had to go down 20 feet multiple times to fix a sink hole, but it sounds like this is a recent problem, so I would think it is a drainage issue and a poor base.
Is it a load bearing wall? What type of anchor system was used?
We usually double+ an inch or two of whatever the manufacturer suggests for a base, sometimes more up to 18 inches depending on water table up here.But we have major frost issues, and six inches does not cut it.
We have never had a "wall settle issue". If the prep work is done properly, and the first course is perfect, nothing should settle, if compaction and the base was done right. Unless you are retaining water.
Just my opinion.
Good luck!

You're right, but he said that the wall itself is not settling, just the fill behind it. He also said the wall is only five courses high, 2.5 feet if it is 6" block. If the wall hasn't moved and is that short, i'd just fill behind it as long as I knew the drainage was there.