Filling Concrete into Hedge Planters - Risks to Foundation?

[Ara Abrahamian]

Hi All,

We have a 4-plex comprised of 2 structures - one structure is built on a concrete slab and the other is on a raised foundation. Both buildings have hedges that are planted into planters that are 12"-20" wide and wrap around the entire perimeter of each building. We are considering removing the hedges and filling all these planters with concrete, but I've been warned that the dirt compactor we'll have to use prior to pouring concrete might cause the foundations to crack.

Does anyone have experience with something similar and thoughts on whether the compactor would crack (A) the slab, (B) the raised foundation, or (C) both? We had 3 contractors come out to provide quotes and none of them raised a concern, but a more experienced investor friend raised the concern.

Our objective is to eliminate water / humidity near the building foundation and also get rid of these hedges that just trap leaves and trash beneath them. If we don't fill in the planters with concrete, our other alternatives are to leave them as-is and fill them with gravel or decomposed granite, but the granite also has a similar compactor concern.

Any guidance would be much appreciated!