Where to get rid of dirty oil?

Let it sit for a couple of days and the oil and water will separate. I have had the rain thing happen a couple of times with the 400 gallon storage tank I put used oil in here at work. The recyclers will not take it without charging you $1 per gallon if it is contaminated. Once it separates you can stick a hose to the bottom and siphon the water out. Stop when you see oil coming out and your good.