What is this tank? Buy this property at auction?

[Robert Campbell]

Hello All:

I am looking at this property at auction and I like many things about it and can work with it, but this is my one red flag - this tank set back about 25 feet from the house.  What is it, oil?  The walls are brick and it tapers out to maybe 8 feet wide, and its 8 or 10 feet deep but who knows because of the water.

There are 3 or 4 rusty pipes going in and out, mostly towards the house.  House was built in 1930.  Yes those are garter snakes.  This is in Illinois.  Whatever this tank is, if it costs me somewhere between 0.00 and 2000.00 to deal with on this project, it should be fine.  Much more than that, I may have to pass.  This is an Auction, so I took these pictures walking the outside of the property - can anyone offer some ideas on what this is and what Im looking at cost wise?

Thanks,

Rob