Dr. Bert Cregg from MSU has stated "Landscapers or homeowners that are anxious to re-plant in Imprelis-affected areas should proceed with caution... Remove any existing affected plant materials since the report from the Indiana State Chemistís office indicates Imprelis in tree tissue is degrading slower than in soil." -http://msue.anr.msu.edu/news/tree_damage_from_imprelis_one_year_later/
So, when anyone including a DuPont rep or your LCO suggests the amount they are compensating for only allows for grinding the stump or does not remove all the roots and surrounding soil, that should be a red flag. Yes, it's more expensive to do the true excavation needed to remove the entire tree and it's roots and replace all that soil (remember that at least 2 feet beyond the tree's roots is also supposed to be removed due to Imprelis residual), but if you think you can plant in that area or next to it you may be losing the new plant too (or it may not grow like it should).
A red maple, for example, has a root system that is twice the length as the tree is tall.