Protecting Blue Spruce Roots During Sewer Installation

Can You Cut Blue Spruce Roots for a Sewer Line?

You need to dig a sewer trench within five feet of the dripline of a 30-foot blue spruce, and large surface roots are in the way. The general rule: you can safely sever up to one-third of the root system without severe harm. To gauge this, imagine a circle at the dripline (where branches end). If the trench cuts more than one-third of that circle, expect some canopy dieback.

Best Practices for Root Preservation

• Conifers tolerate root loss better than hardwoods due to a deep taproot that aids water and nutrient uptake.
• Most roots are in the top two feet of soil, so trenching will cut through them. Dig the trench but keep heavy equipment off the root zone on the tree side.
• Do not cut exposed roots outside the trench line. You can cover them with up to two inches of sand.
• Fertilize after construction: Apply 10-10-10 at 1 lb per inch of trunk diameter, scattered and watered in (or timed before rain).

With careful execution, your spruce should weather the disturbance.