Question
I want to install a 12 ft wide circle drive made of pavers completely around a very large live oak. The inside drive edge would be 14 ft from the trunk of the tree. The branches and their leaves hang at least 20 to 30 ft from the trunk. There will have to be light dirt grading to level ground around tree.  Will this harm the tree?

Answer
Yes it will damage the roots of the tree. To what extent will depend on the amount of soil that is moved when grading and the percent of the root system that is damaged. The tree can do fine with as much as 25 percent of the root system damaged without much problem to the the foliage. When roots are damaged he tree can not produce enough food and water to support the total foliage and some foliage will die back. The roots are within the first two feet of the soil surface and extend out about 1 1/2 times the width of the foliage. You can figure the percent damage by out lining the roots width and deleting area that will be damaged. IF this is more than 30 percent the tree will exhibit a good bit of foliage damage and die back. IF hti si daone you will need to add water to the tree for the first couple of months. And do not let the machinery go beyond the graded area even to turn around. This will compact the soil and add to the root problem.