I have a very old (about75 years) live oak. 4 months ago the city put in a new water meter and dug a trench directly underneath the tree from one side of the canopy to the other. Also an irrigation system was installed in the area. Obviously, the trees leaves have all turned brown and are dropping. Is it likely that the tree is already dead or is there a chance that it will recoup in the spring? Anything I can do for it at this point?