Can you imagine 3 to 5 FEET of rain? This has not happened in thousands of years anywhere on Earth.

Yes it has. Pretty regularly in places like Reunion Island and the foothills of the Himalayas. But they aren't concreted-over flat-as-a-pool-table urban-industrial conglomerations.

Something more to worry about.

https://consortiumnews.com/2017/08/30/worries-about-a-galveston-bio-lab/

They seem to have done their best to design it safely, but you have to wonder if there might not have been better places to put it.