Q: Thank you for answering our question. My wife planted 3 Dwarf Alberta Spruce trees right next to each other over six years ago and they are now 7 to 8 feet tall.
The problem is she planted them to block the obstrusively looking heat pump and the location is right over the main sewage pipe from the house to the septic tank. Are these roots strong enough to damage a pipe or the concrete side of a septic tank??
Roots generally require a breach in a sewer line to be able to enter and exploit it. Unless there are seams or cracks present, the roots will probably not be able to get inside to cause any problems.
However, if there is a breach somewhere, and the sewer line is shallow enough to be in the root zone of the spruces (probably 2' or less), then the roots may find their way inside.