Ask Mr. Smarty Plants

We are surprised the city would recommend planting a tree that close to other structures. Those are all good native trees and will do well in Central Texas. However, as you pointed out, you have a very small space with underlying pipes. You have to be aware that the root system of a tree is usually two to three times the circumference of the top of the tree, or "shade line." A small tree could probably be fitted in there, but all three are going to grow and grow. Before long, you could have branches against your front door, or out in the street, sidewalks buckling and a fence being pushed down.

Unfortunately, as good an idea for the environment as the "free tree" is, it would soon be costing you maintenannce money and/or would have to be taken out because of the root interference. In the meantime, you would have spent resources such as time, fertilizer and especially water on a plant that isn't going to last. Small herbaceous plants, native ornamental grasses and perhaps some very small shrubs will still absorb carbon dioxide from the air and emit oxygen in the same manner as a large tree, without disturbing the infrastructure of your property.