It was the pool "deck" area that was the main (but not only) area that was of concern to the engineer in 2017 and the engineer in 2018, as well as the pool contractor in this story:
The deepest puddle of standing water, according to the contractor, was located around parking spot 78 — an area that building plans show is located directly under the pool deck where in a 2018 inspection report, engineer Frank Morabito had flagged a “major error” in the original design that was allowing water intrusion and causing serious damage to the structural concrete slabs below.
The deck area around the pool was quite large, next to some of the parking. In the two pics posted here, you can see that part of the pool deck collapsed (the actual pool would be just below the bottom center left side of the 2nd photo)