Frozen line?

[POOMAN]

How do you keep a pvc waste line from freezing that runs from the house to the tank . My customers line keeps freezing where the pipe runs under her gravel driveway. I'm looking for a cost effective way to insulate the pipe.

[plowking]

Usually the pipe should be sleeved inside a larger diameter pipe under the driveway to keep the cold from transfering from the ground to the smaller pipe, you can also lay ridgid styrofoam insulation[ similar to foundation insulation] in 12 or 24 inch strips on top of line before backfill to keep frost out. I have one we did this to,last year was first time it hasn't froze. If the pipe has a low spot it could freeze from standing water not draining completely to the septic tank. plowking