1980 Astros

The answer is pretty heavily reinforced! Check out this nice little progression: (This was during the forming of the main foundation underneath the Maternity Center on the north side of the site.)

I just happened to be browsing around the internets and noticed this project posting. HAIF is always something I've followed, but I've never really thought I could contribute anything meaningful! That being said, I work fairly close with TCH, and I'd be happy to answer any questions I can about the goings-on of this project.

All of the sub-grade floors of the hospital are all going to be for parking. TCH wanted to add a bunch more parking spaces without adding an additional garage, and so they decided to go down 4 floors. When the hole was at its deepest, it was 5 feet below sea level, which is about 55 feet deep. In areas outside Houston, this isn't too remarkable. However in a town where the water table can be as shallow as 8-10 ft below the ground, such a big hole is quite remarkable. Busted :-) The buildings are indeed designed to go much higher. Currently, there are two buildings scheduled to go up: a 17 floor maternity center, and a 7 floor pediatric hospital. Both of them have been designed structurally to go up to 24 stories each. However this has nothing to do with the hole. The hole was so deep simply because TCH wanted more parking.

There are massive permanent dewatering systems in place at the new TCH expansion to prevent future Allison type issues. Additionally, for a little trivia, the Maternity Center hole-in-the-ground is the deepest hole that's ever been dug for a building foundation in Houston, ever.