I have an old above ground oil tank in my basement, along with an old oil burner and oil hot water heater, and a washer/dryer. The oil tank is empty, except maybe for some sediment and/or sludge at the bottom. I am converting to natural gas heat. I want to save as much money as I can. I saw a few ads on Craigslist (New York City-area) for guys saying they'd take all of this junk away for free. Are these ads legit? Can these guys be trusted to remove the oil tank safely? Will they just cut up all the pipes that connect everything and leave me with major plumbing repairs? How do they prevent any possible leaks of sludge and/or sediment? Has anyone used one of these guys? Any details on your own experience with these kinds of guys would be really appreciated and helpful. Thanks!