Question
we planted two trees in same location, were dying, moved and lived...we dug 6 x 6' squre and a little over 1 1/2 ft of soil out on the spot..has some oil streaks in upper portion of soil dug..how can we remove the rest, if any lower down to replant a tree in this location..

Answer
Hi Donna, The best way to remove the oil is exactly what you did - remove and replace the soil.  Replace the soil with exactly the same type soil you removed to prevent creating a bowl effect with a different type of soil. You shouldn't need to go deeper than 18".  Jim