Not to be harsh, but you need to educate yourself about the business of real estate investment and how to be a landlord, or get out of the business.  

I don't mean to be harsh but there are a lot of holes and assumptions in your analysis.

"low lifes" is a little harsh.

I am a recent graduate with a degree in chemical science.

I sold my current property for a considerable amount less than projected, due to a harsh learning experience and a vicious lesson of location, location, location.

You can even put them in the walls in the existing wall system.Chances are the old pipes in the flooring are copper or steel and the chemicals in the cement  use to work on corroding the pipes over time. 

The other approach would be to sell it, but don't expect top dollar on the sale, this is a project to turn around.Not intending to sound harsh or make this personal, so please don't take it that way.  

where there any issues as to the chemicals they use?

Well maybe crash is too harsh.

that would bring in about $50,000 to $80,000 per year after expenses.Bit of a mess, but I keep going round and round and I have to make some harsh decisions very soon.This is an attempt at clarification of my situation to some more experienced heads out there.Many thanks for any advice, James.