Seller is insisting on cash purchase as bank will not finance due to environmental concerns.Is this property worth further investigation or should I not even touch a potential contaminated site with a 10 ft pole?

It is a good description along with the two links at the bottom of the page:http://www.ontariotaxsales.ca/how-to-buy/what-is-a...What this does not seem to make clear is how to KNOW what you are buying instead of HOPING that you aren't buying an environmental disaster that bankrupts you or some Crown lein that halts your business for years of repayment.

What are some strategies I could use to protect my investments not only from legal and environmental events but from market fluctuation and retracements?

Both of these elements will certainly impact the types of buyers and offers that you'll receive.

I asked support about posting this message and they said I should put it up in the forums so here it is:I have a superior mold remediation product and want to make it available to members- it is the lowest cost, laboratory proven, environmentally safe solution available.  

You can include electricity in the rent or lease the panels to tenants, but it now falls in the category of great environmental thing to do, and the math works out, as long as you can find a way to sell the energy, which is what my startup is trying to create a system for.

Once you are able to find a site that is already zoned for multi-family- because rezoning to multi-family is very difficult- and tie up the site with an earnest money deposit, you've then got to engage professionals for: surveying, land planning, civil engineering, geotechnical, environmental, architectural, MEP design services.  

The learning element and guidance by pros are priceless.

@Costel A. and @Christian Bors, The most important element in this discussion is your ability to demonstrate under audit that you had the intent to hold for rental, investment or business use. 

Growth most likely involves some element of risk or park it in a bank and draw measly returns.