This cuts off the water supply, too. For some tree species, like red oak, only a few inches of fill is enough to do serious damage. If the tree is already showing symptoms of advanced decline, it probably cannot be saved. If it appears mostly healthy and there is more than ten inches of fill anywhere inside the dripline, restore the area to its original contour by removal of all the fill. Avoid soil compaction, only use hand tools to remove the last ten inches of fill.
Soil compaction is by far the most common way construction damage can harm and kill trees.
Tree roots need crumbly, well-aerated soil to grow and to obtain oxygen, water and nutrients. Lacking good soil aeration, roots suffocate and tree health declines. Leaf wilt, early fall coloration, branch die back, overall decline and tree death are symptoms of soil compaction. Most soil compaction is caused by construction equipment. One pass by a heavy tractor or truck is all it takes.