Question
We like to plant a japanese maple in our small - very small - backyard.  The soil where we live is clay.  We've dug to a depth of 3 feet and hit hardpan.  How deep must we dig for a japanese maple.  (Is it a problem that there's a drainage pipe less than a foot away from the hole we dug?)

Answer
Three feet deep is good enough for the root system of Japanese Maple. When you plant the tree dig the hole twice the size (width) of the rootball of the tree and as deep as you can. Plant the tree level with the top of the rootball. Fill the excess with a good top soil and mulch. I assume by "drainage" you mean a down spout from the roof of the house--if so this will not be a problem.