This was done in 3 stages. Stub-ups at the gen pad locations (8) Cat gens, 13.2KV, 2.5 MW each. Two (2) chiller feeders and control. The tough part is what's in the pic...getting thru the foundation.footings to the interior. Tight squeeze.
After the slurry pour, tape, clean backfill, there's a 10" concrete pad over it. (Not counting the gen pads @ 14" above)