How to excavate near the base of a huge oak tree without killing the tree?

At my mother-in-law's house in the New Jersey suburbs, there's a massive, old oak tree. I don't know how old, but it's at least two feet in diameter and 50 feet tall. Unfortunately, the base of the tree is a few feet from an underground oil tank, which isn't leaking but has to be removed for legal reasons. The local oil tank guy wants to come in there with heavy equipment and the local arborist says there's no way to do this kind of work without destabilizing the tree, so the tree has to be taken down.

This hurts my heart, because the tree is perfectly healthy and beautiful and provides lovely shade and acorns and mulch. And it'll probably cost a fortune to do it too, because it's huge and branchy and within 10 feet of two different houses, so it will require a lot of skill and care.

So I was wondering: does anyone know how I might find someone familiar with oil/toxic waste issues, who could remove that tank with a crew of guys with shovels, rather than a backhoe, so that we can get this tank out without killing the tree?

Does the tank have to be removed or can it be filled with sand? Here you can fill them rather than remove them if removal is difficult. we have an old one somewhere close to the house that is filled in. The previous owner didn't know exactly where either.

My understanding is that the tank has to be removed so that they can take a good look at it and the soil under it to make sure that there's no contamination from a previously unsuspected leak.

That’s a damn tragedy. It might cost more, but could you find someone to get in there with smaller heavy equipment and hand tools to excavate around the oil tank, then pull it out laterally?

It's a terrible shame. I've been researching this extensively. Unfortunately, I can't find anyone who is willing to take the risk and liability of excavating near this tree without taking the tree down. Basically, if anyone goes near those roots and the tree falls at any point in the future, like ever, they could be sued. And if it did fall, it could take out some very expensive real estate and kill a bunch of people, so that lawsuit would be quite rough, even if it was basically without merit (and it might actually have merit).

So, against my deep wishes, I think the tree has to be taken down.

My next question, then, is how can I find the best possible home for the wood? It's going to yield hundreds of board feet of oak, up to four feet wide, which seems like it ought to be worth something to someone. How do I find these people?