Originally Posted by brithgob
With trees, could there be a concern about roots destroying underground infrastructure?
Depends on who you ask, engineers will likely say yes, landscape architects and urban foresters will likely say not really. There are certainly examples of large trees heaving sidewalks, and getting into sewer lines. The heaving of sidewalks is usually because no one has cut the sidewalk away from large trees, they have remained in their original holes. As for roots in the sewers, I don't think this is much of an issue with current pipe technology, but does cause issues for old cast iron and clay pipes.
The issue in Regina as far a trees in the downtown goes is, in my experience, two-fold. One, the planting pits we have provided for trees in the sidewalk are too small to support healthy tree growth, and are too small to be excavated by machine. Therefore the pits for replacement trees are hacked out of the local clay by hand with a pick-axe and shovel. Not work that anybody relishes, especially folks who already have too many much easier places waiting for replacement trees. Secondly, the survival rate for street trees in the downtown is very low, due to the small size of tree that can be planted in our small pits, the clay pits, and a certain amount of abuse that is traditionally visited on the new trees by say late night revelers.