Just finished digging up and replacing a frost free hydrant that was shot. It is close enough to a maple tree that the roots had plugged up the drain at its base. The tiny little hair sized roots were grown into the pea gravel that I put around the bottom of the hole years ago making it about like soft cement. I put about three bags of pea gravel back in the bottom of the hole before backfilling around the new hydrant. I'm hoping it will be a long time before doing this again. Any suggestions on keeping the roots from coming back with out killing the tree? I thought about mixing up a strong bleach and water mix and letting it siphon back into the hydrant drain periodically.