Tree Roots Buried by Construction Fill: Why Your Trees May Decline and What to Do

A homeowner replaced a septic system, raising the drain field 18 inches. The contractor pushed soil up to the trunks of four trees. Eight maples were already removed for the field. She wants to protect the remaining trees with a U-shaped barrier.

The Real Damage

Covering the root zone with as little as 2 inches of soil can kill a tree. The root zone extends roughly twice the canopy width. Soil on the trunk is bad, but soil over the roots is fatal.

Outlook

If only part of the root zone is covered, roots on that side die. Over the next few years the trees will decline unless the fill is removed to restore the original grade. If that's impossible, plant replacement trees this fall.