Thank you for the pictures. Can you take a few further back to show some context?
Thank you. That is helpful. I will need to research this. I've never seen plugs that small. They appear to be about 1" is diameter. Is that accurate?
Hello. I apologize for the delay and thank you for your patience. I have done a lot of research on this, because it is quite uncommon. From everything I can tell, this is typically done to allow pressure grouting for sunken slabs in very lightly loaded applications. The reason it didn't stand out to me as that initially is that every pressure grouting situation I've been involved with has had much larger diameter holes spread further apart with real structural loads, not just a sidewalk.