You have to wonder if Playtime Co. is sound proof in a lot of places to hide the underground labs and the Shelf to keep people who are out of the loop from questioning what is going on and why a toy company needs more underground construction. There would be a lot more people witnessing the transportation of materials unless they're doing it when the employees in the dark are not there. I would imagine having loud noises around distressed experiments who could tear your head off isn't safe.
For that matter, Playtime Co. would have to be in a place that earth quakes and flooding are extremely rare and hope like hell one slip of machinery, rock, or support doesn't create a sink hole effect for the rest of the building. Yeah, they have Warrenbach Construction backing them up, but that doesn't stop accidents from happening and causing mass destruction. Not to mention possible collapses from the train tunnels.
You seriously have to question Poppy's plan when you realize she has ZERO expertise in demolition and hope like hell you don't just bury yourself, the experiments, and the orphans all in one go, especially in an area that's still unfinished.