How Close Can You Trench to a Tree?
Construction and repairs sometimes require trenching for the installation of pipes near trees. This trenching can damage the root system of the tree leading to health issues, or possibly stability issues, for the tree. Proper planning and a knowledge of the trees in your area can prevent problems. In some situations underground boring below the root structure is preferred over open trenches. Does this Spark an idea?
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Root Location
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The bulk of the root system lies less than 24 inches below the surface in a radius around the tree equal to its height. This is the area you need to protect. At least half of the root system should remain undisturbed during any trenching or construction process. This preserves roots necessary for absorption of water and nutrients and the stability of the tree. Some tree species tolerate disruption of the roots better than others. For example, elms and hackberry have a high tolerance for this type of change while locust and spruce have a low tolerance. Contact an arborist for specific recommendations about your trees.
Protecting Young Trees
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Young trees, trees up to 4-years old, tolerate disruptions better than more established trees. Protect the area inside the dripline. Arborists define the dripline as the point on the ground directly below the outside branches.
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Protecting Mature Trees
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Trees older than 4 years require a little larger protected root zone. Measure the diameter of the tree trunk and extend the protected area beyond the dripline by 1 foot for each inch of diameter. For example, if the tree trunk has a 5-inch diameter and the dripline is 10 feet from the tree trunk the protected area would be a circle with a radius of 15 feet around the trunk.
Tree Damage
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Along with root damage, homeowners should avoid damage to the tree itself. Excavators and other heavy equipment can break branches and damage bark when working close to a tree. Depending on the severity of this damage, it can threaten the tree or negatively affect its appearance.
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