Dawn Redwood heaving sidewalk.
I live on a residential street in a city on a hillside. Just above my property on the other side of the street is a seasonal spring in an empty lot. On my downhill property line are a pair of large 22" diameter breast height Dawn Redwoods. One is sending out a root across the street toward the spring and forcing up my sidewalk. Prior to moving in it was so bad they repaved the road because it had heaved up the whole road. The base of the tree is only inches from the side walk.
What I am wondering is once the concrete is up how aggressively can you root prune a tree of this size? If you are only taking out one root but it is a huge one is that enough to kill the tree? Once it is pruned do you need to cover the wound in some way? I have been calling aborists but no one has gotten back to me yet. I have read that when you transplant conifers you can prune up to 1/3 of the roots at the drip line then a year later do the same then, move the tree, but I am sure cutting off a root at the base of the tree would have far more dramatic effects.
Anyway if anyone has experience with root pruning on this scale I would love any wisdom or advice you might have.