It has a brick facade around the perimeter but underneath it is on pillars connecting to the steel beams.

Pipe backed up in crawl space underneath home, and I need a company that can pump it out and treat.

Of course this soaked the soil in and around the foundation on that side of the house, and when the holes were left open, water then trickled into the holes.  

He inherited it from a family member & believes there still could be a tank underneath the parking lot where the gas station previously sat.I know any lender will require a Phase 1 & a Phase 2 bc of this.

Similar to what Bonnie mentioned about baths, I would add that it says 'dedicated bathroom' underneath the photos which as a recent one month Airbnb booker, I was looking for, but then in the description it says shared bathroom. 

and underneath a 6" ball.

In cold climates you want to make sure the deepened perimeter of the slab is below the frost line so the expansion of frozen soil doesn't heave the building up, but if it has been fine since the 50's you should be ok.

What I have found is that when you hire the right GC, you are getting all reliable subs underneath them.  

You still have to get all the site work, including the site plan with set backs, foundation, soils tests, grading, etc. all approved by all the municipalities.

With 100 years water had plenty of time to flow all around and under the house, micro streams and variations is water retention in different soils will cause uneven settling.All in all you may have a real gem that just needs some love.