Sewer line freezing from pump chamber

[Waxman]

It has been an extremely cold winter and we have had 5 freeze ups in our sewer line.

We have a pump chamber with 2 grinder pumps that pump the water out of a tank. We built the car wash new in 2006. Years ago we installed a nipple with a cap to insert a thaw tube. We made a pex line coupled to hot water hose and it's a pretty quick and easy way to thaw the line, which freezes anywhere from 3' to 15 feet from the tank.

Has anyone else come up with a way to prevent freezing like this or do I need to excavate the sewer line and bury it deeper?

 

[Eric H]

How deep is it? Is it pitched properly? A flat spot or shallow pitch could cause pooling in the pipe that could lead to an ice dam type issue. is there a vent on the sump tank and the drain pipe that is allowing cold air to pass thru the pipe causing the freezing?

 

[Waxman]

Yes I am putting more layers of blue foam insulation over tank access (under man hole) in a few minutes. I will see if that helps. This has been a problem since new, so maybe pitch and depth are incorrect.

Another idea I had was running heat cable down into the chaseway (PVC) that sewer line runs in.

 

[Waxman]

Yes I am putting more layers of blue foam insulation over tank access (under man hole) in a few minutes. I will see if that helps. This has been a problem since new, so maybe pitch and depth are incorrect.

Another idea I had was running heat cable down into the chaseway (PVC) that sewer line runs in.

update: i covered the hole under the manhole better with extra blue foam insulation and a blue tarp and no freeze up with a -17 degree night.