Utilities that have PCB contaminated oil (above 15 parts per million) are required to track it all the way to 'final disposal' by the EPA. The fines are substantial - in the range of a thousand dollars a gallon per involved entity (company, individual, etc). Last time we had an 'incident', EPA collected the same fine from, us, the registered company we delivered it to, the company they transferred it to for 'final disposal' and the jerks that got caught with it. The third party went out of business -bankrupt, and the fourth parties went to jail. That was over 20 years ago, and we were paying $25 a gallon for them to take it, before the fines we got socked with.
BTW, a generating station transformer can have more than 20,000 gallons of oil in it.
I've learned a couple of things over the course of my life. One is that there is what is supposed to happen, and another is there is what does happen.
PCB is one such case. Utilities are well known, to the EPA, to be a source of PCB laden oil. It would be hard for them to get away with much of anything these days... they have a lot to lose from not following the rules.
But there are junk and scrap yards that have been in existence from back when PCB was considered non-toxic, and a godsend to industry. Back in those days PCB was found in many places you would expect it: pole pigs, X-ray machines, large HV capacitors, and in many you would not: carbon paper, mimeograph paper,, typewriter ribbons, teletype re-inker's... I recall that it even made it into cosmetics at one point.
I have found barrels of unmarked PCB laden oil in government auctions, in old scrap yards, at surplus electronics dealers. Even in residential neighborhoods! In spite of all of the publicity, and maybe even because of all of the publicity, it is still out there! Many of the Joe Sixpacks that know they have a barrel of smelly old oil, are highly motivated to make them go away. They know it is expensive to dispose of properly, so if they can find a way of getting someone to take it from them for free, they might not pay too much attention to what happens to it once it leaves their back yard.
If you are going to burn waste oils, it pays to know what they really are, and what they become when you burn them.
-Chuck