All,
Thanks for all the advice and experience. After helping a neighbor cut off an oak resting on his transformer box, I gained new respect for the action a root ball will take after release.
I took another look at the trees: all poplars except one oak, each about 15 to 25 inches in diameter, about 50-60 ft high with the first branches starting at about 40 feet. Each has its top hung up in another one or two trees. Attaching a line/cable seems the safest way to control the fall using my 4x4 pickup and a tackle to move the tree away from the septic leach field. Problem will be to attach the line/chain at a point sufficiently high to get the leverage to pull the tree free. MossRoad, you may have to help me figure out how a noose chain can hold up high enough without slipping on a nearly vertical tree.
GregJ, I can't submit an image since I have no way to scan it.
WCarlson, I will do a search on the Humboldt notch (didn't know it had a name). If I can't find it, I may have to ask for your help. By the way, my wife grew up in the Finger Lakes region near Elmira, a little town called Odessa. Beautiful country, but the winters are fierce.
Again, thanks to all for the help.