Filling a hole to stop a wall moving

[Hairy Ape]

We recently had some drain issues and had to lift the concrete flags in the yard to find the inspection chamber to solve the issue.

The old clay inspection chamber is adjacent to the wall at the end of the yard. There is also a rather large gap between the two where it looks like someone has previously dug it out to replace it. 

Where this gap is, it is causing movement in the yard wall.

My question is what is best to use to fill this hole and stop and further movement?

Any advice is appreciated

[davyp1]

A photo would help for more clarity, but from what you say, back fill of the hole using a lean-mix concrete would prevent any further movement.

Davyp1

[Hairy Ape]

Hi davyp1

I've managed to get a pic that I hope will explain everything a bit better. It's worse than i remember. The hole extends under the course of red brick, which is moving and causing the wall above to move.

Does your advice still stand or is something else needed?

Thanks

[cotswold builders]

If theres still movement, dig around the drain and under the wall, you could have collapsed drains.

[Hairy Ape]

Hi Cotswold builders

The drain runs just to the right of the hole and has definitely not collapsed. It looks more like they couldn't be bothered to back fill the hole after doing some work there.

What would be best to fill the hole with to stop any further movement ?

[wes56]

is that wall the house wall or a backyard wall?
thats not an inspection chamber. its the square top hopper head of a gulley, could be a trapped gulley.or maybe a straight upstand without a gulley?
anyway, the hopper head top is cracked.
where does the drain go to ? is there a nearby manhole in the yard or just outside it?
could you clear out the gulley and drain pipe and clear away all the soil debris around it?and lift up the flags on each side.

you want to find out the extent of any water undermining of the brickwork and if the drainage is not blocked..

[Hairy Ape]

It's a yard wall. The common foul drain/rain water drain runs under it and out into the common sewer in the back alley. The square head has a round cast iron grid over the top. I'll have to look in the next few days and lift the flags to get more photos to show the extent of the hole.

I know that if you lift the grid you can see straight into the common drain.

[davyp1]

Sorry that I did not get back to you earlier.
I agree with and 2nd all the points that Wes has raised above.
Yes please do post some more photos.

Davyp1

[Hairy Ape]

Ok lifted the flag over the gully and couldn't quite get the other one up. I could see through the gap and if I had to guess it looks like someone has dug around the gully at some point. Maybe to replace it. The drain is intact and hasn't collapsed. The dug out area seems to extend a bit under the wall. I've tried to take pics as best I can.

The crack in the gully is just the corner part of it so it's largely in one piece.

[cotswold builders]

Sorry that I did not get back to you earlier.
I agree with and 2nd all the points that Wes has raised above.
Yes please do post some more photos.

Davyp1

Why did you originally suggest backfill with dry mix. ?

[davyp1]

Sorry that I did not get back to you earlier.
I agree with and 2nd all the points that Wes has raised above.
Yes please do post some more photos.

Davyp1

Why did you originally suggest backfill with dry mix. ?

My suggestion of backfill with lean-mix was purely considering pinning the wall.
I accept the suggestion was somewhat premature considering that I had not seen a photo at that point!

Davyp1

[Hairy Ape]

Hi gents

What would you recommend having seen the photos?

Thanks

[davyp1]

Looking at the photos, my feeling would be to locate the manhole that the gully in your last photo runs to.
Next step is to clean out that gully top and as far as possible the trap which should be below it.
As that is progressing, identify which drain outlet in your manhole belongs to the gully. Once done, try the drain rods up that
outlet say with a worm screw on the end, If you have no joy in clearing the drain, identify the location of the obstruction using your drain rods (mark a point on the rod with tape when it has reached the obstruction. Then lay the rods out on the ground annd mark where the obstruction should be. Excavate the area until you have exposed the pipe. The pipe may be broken.
At this point I would suggest you proceed to this stage and report back with your findings.

Davyp1

[Hairy Ape]

Hi Davyp1

The drains are clear. My issue is with the free space surrounding it. I want to back fill but not sure what material to use.

[davyp1]

Hi Davyp1

The drains are clear. My issue is with the free space surrounding it. I want to back fill but not sure what material to use.

You say the drains are clear! Looking at your last photo, this is not indicative of that. The gully top looks to be full of crap.
I take it that you have cleaned this out and rodded the drain line.
Before you backfill the hole, you need to remove any loose material in the bottom of the hole till you have firm ground. Then as I said at the outset, backfill with concrete.

Davyp1