Question
Hello:  we have a beautiful 35 year old Colorado Blue Spruce in our front yard.  The city is widening the road and the city owned property line is approx 3 feet from the trunk of our tree. We are concerned that with this construction they will damage the roots thus killing our tree. The city "verbally" claim that any trees, shrubs, etc on the owners properties will not be damaged. Can you confirm this for us? It is one thing for them to say this, using the engineer drawings, but it is another thing when the construction company starts doing their thing.

Answer
A trees root system is mainly in the first two feet of soil (some conifers have a tap root also)  If more than 30% of a trees root system is cut the tree will show damage by the foliage  and branches dying back. If you draw a circle around where the branches extend to and then cut the area off that will be cut this will give you the percent roots damage. I would say without seeing the tree that a cut along one side 3 feet from the trunk will cause major damage to the tree. I would try to have the city give you in writing that the tree will not be damage and if it is they will pay for damages and a new tree. I would put up some type of temporary barrier along your property line so the machinery will not get on the remaining root zone. You will need all the roots from the remaining system to be healthy to over come the damage.