[Oztrich Boy]

If it were me I would metal detect only the area that the saw is going to cut through at the base. Then when they are hauled into the mill yard and are laying down, have them checked out completely with the detectors.

That does not guarantee zero risk

No there's only one solution here. Burn the forest to the ground and replant (It's the only way to be sure)

Tree bad, Fire Pretty.

[D Rider]

Clear cut by cutting the trees at about 10 off the ground. Then bulldoze the stumps into a great big pile and have a bonfire party.

[fish hawk]

This is the 21 century and the United States of America. We make good products to detect metal in wood. Your idea of burning is dumb. At the very least you could but them through a chipper where some nails would make no difference to chipper blades. At least maybe get some paper instead of wasting the whole forest as you suggest.