Ugh, I try to stress the importance of inspections to my investors, but some don't listen then complain when something major was found behind a wall they were working on, or the pipe that looked good on the outside was horrifically clogged.

The property still has not sold and it is now suspected the owner was quite aware of the presents of the USTs.In the case of the residential property - the presence of an old boiler and a copper line going out through the basement wall led to questions, which led to the discovery of a tank which the Vendor (an estate) had remediated.In your case, the bank/lender may well have been unaware of the presence of a UST, especially if it was no longer in-use.  

Other possibilities include companies that provide indoor climbing walls, theatre groups and bands that need rehearsal space, athletic groups that need to train in winter (lacrosse teams, roller derby.)

You'll need one on every wall.

We were removing and moving some walls, some of which were load bearing, and we needed to pull permits.

Wall St. doesn't make the same mistake twice this soon (there a whole bunch of new mistakes to make!)

and i agree completely with @Mana Silva that rehab presents (for me) too many unknowns inside those walls whereas, once i'm outta the ground on a new build, i KNOW everything is in brand new condition and placed in working order (and can of course sell it for more).  

The insulation in the wall is black because it acted as a filter as the air passes through it, moving from the outside inward.

They don't want to spend the money on anything - to make the building safer (we have a number of people that are jumping over a wall and break into cars and steal other things) etc.

(If you have the information to daytrade like this, you should quit real estate and go work on wall street)