I am purchasing a property 3 blocks away for a large, well-known medical establishment (3 hospitals, bio-science facility etc.)-  20 minutes from dt Denver.

My stepdad built, ran and sold several storage facilities years ago among other endeavors, but I haven't picked his brain on it too much since I haven't had land to put any on.

Are there any underground problems like old oil tanks from houses or other problems lurking?

The home used an underground oil tank (huge red flag for me).

I've also seen various nurseries bought out (Dardano's on Evans is now a grow facility).  

Use oil base kilz, that worked for me, stronger then latex kilz.

When oil was discovered nearby, oil patch workers flooded to the area, and our houses literally doubled in value. 

It sounds like they are trying to drum up business for candle/Tupperware/essential oil/Mary Kay parties, (the list is endless) or religious activities where all might not be welcome.   

The only (recent) cases in point I can think of, related to S/D imbalance, are the cities that experienced the fracking/oil boom phenomenon.

If a Bicoin, political instability, oil prices, local company stock prices erode people will realize they should have done this or that earlier.