If the work has not been completed by closing, the buyer can walk with the earnest money.You could negotiate a five digit escrow at closing to mitigate this risk ( unlikely the seller will agree I'm sure)You could gamble buy it and hope there is no contaminationYou could require the seller to produce a recent Phase 2 environmental showing no spillage or ground contamination and with that buy it and remediate the tank yourselfIf the seller balks at options 1 or 2 or 4, then all you can do is watch the listing age out and test the seller for motivation every month or so.

If not that would be my first step, also be sure to get a phase 1 environmental done to ensure the ground is not contaminated.

there have been a number of articles about the contaminants at former housing sites. while EPA has removed the more obvious debris, there can be all sorts of contaminants.

Could be heavily contaminated? 

But, as in most things, you would list that the sale is base on contingencies such as getting schedule E’s, passing inspection, getting copies of leases, appraising high enough, getting financing of at least X% of the value, no lead/radon contamination, zoning and permits are clear, etc...  

So, yes liability is a concern.Your municiplaities concern is going to be ground water contamination.

Your vinyl floor is also contaminated.

A structure is unfit for humanoccupancy whenever the code official finds that such structure is unsafe, unlawful or, becauseof the degree to which the structure is in disrepair or lacks maintenance, is unsanitary, vermin orrat infested, contains filth and contamination, or lacks ventilation, illumination, sanitary orheating facilities or other essential equipment required by this code, or because the location ofthe structure constitutes a hazard to the occupants of the structure or to the public.

This industrial area has a lot of contamination so dampens value so was thinking perhaps there was a play here. 

And, there's a history of industrial contamination.