And in the 1930s during the Great Depression, there were little environmental concerns or legislation. 

You may need Phase one environmental report too.

It stopped operating over 5 years ago, but it still has to be tested for potential pollutants.

Historically this has proved very reliable long term but especially the property prices have experienced short periods of depreciation (virtually always less than 5 years) and longer periods of stagnation.I make no claim as to continuing property appreciation as I could make a decent case for the RE market entering a period of stagnation, the market continuing to appreciate, or the market to depreciate some.However, I am still confident of rent appreciation in my purchase area (San Diego) for at least the next few years: 1) rents lag property appreciation. 2) vacancy rate is real low. 3) cost to add more than ADU is high - it costs around $100K to break ground for residential in San Diego (permits, surveys, etc.). 4) Minimum wage increases already approved. 5) one of the best weather climates in the US. 6) rising population: one recent study had San Diego as 13 highest population increase of large US cities. 7) geographically constrained: Constrained by Mexico to the South, Pacific to the West, Camp Pendleton to the North, and the East quickly gets harsh. 8) good and varied employment: Hard to imagine an employment category melt down that could impact the range of employment in San Diego. 9) environmentally diverse from mountains to desert to beach to happening urban center.Last weekend I sent out 2 rent increase notices.

Going to have an environmental inspection as well as part of my due diligence.

After 40 years as a lender and borrower, I've seen approved deals tank on sudden changes in terms, pricing, failed appraisals, environmental issues, undisclosed bankruptcies, criminal records and a host of other unforseens.

Can you just come in and drop new tanks on the lots or is there an expensive environmental remediation required?

below ground means it's a burried tank, most likely the building dept will want it excavated and new one installed either in the basement or above ground. if you buy a property with a below ground oil tank it can be an environmental night mare if it fails a pressure test and is leaking. the soil around the tank will need to be professionally removed and hold off to an approved facility. you will have the Dec and building dept watching every move. make sure you get quotes to get an approximate idea of costs on this and add that into you purchase offer, be very well prepared to take on a project like this when buying with a below grade oil tank

Go in front of council to argue your point and they may make you do studies like traffic or environmental.  

There are either major repairs that need to be done, zoning or environmental issues or it's just not a a good deal.