It looks like the septic-line-insulating-dirt-berm-operation (SLIDBO) on the 18th has halted the coldward temperature trend on the east-west section of the line (middle trace on the graph below). That is good because it is only 4 degrees from freezing. Air temp outside has been below freezing for a week. Now that there's more dirt on top I hope some heat from the ground can migrate upward and warm the line or at least offset the cooling trend. It's only November.