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.