Open Discharge Septic Freezing Issues

[jgab]

We currently have a open discharge septic system. It's really quite simple and works great - when it doesn't freeze. It is a two chamber tank and when the effluent engages the float the pump moves the effluent out over the course of approx 60 feet. The discharge pipe runs approximately 40 underground and comes up and out of the ground and discharge it into some bushes.

We have lived here for about 10 years and never had a problem with freezing (we are in western Canada). We had to swap the pump in the tank last December and then had some issues with freezing in the pipe that came above ground. Never having this problem, I wasn't really prepared to deal with it. I ended up with some pipe tape and insulation on the exposed run of 20 feet of pipe and went through the balance of last winter with no problems.

I usually pop my head out the front door after a bath (or something that uses a decent amount of water) to listen for the effluent being discharged so I know I don't have a freezing issue as I can hear it in the distance. Yesterday, I had a freezing issue at the very end of the discharge pipe. Not a big deal as I didn't hear it, so was able to fix it without finding some nice grey water in the basement.

My question would be - what changed from when we switched out the pump (I'm by no means a plumber)? Is there a valve or a certain type of pump that allows that water that is in the pipe to run back via gravity back into the tank once its finished pumping so the pipe that's above ground won't freeze? I'm assuming this is the issue. I've also heard that a small hole can be drilled out in the pipe in the tank so the water can flow back. I'm assuming that there isn't a hole since this issue has come up since the switching of the pump. At a loss really, the heat tape is great - when it works and doesn't fail. Looking for more of a hands off solution.

 

[RS]

I'm surprised you can use a system where the effluent is discharged above ground! Anyhow, do you still have the old pump, maybe the old one didn't have a check valve and the new one does? I installed a similar system for our sons sump pump, (not effluent) with a vacuum breaker at the high point so the water could run out of the pipe outside, and the water inside ran back into the sump.

 

[GReynolds929]

Ideally when it was installed the horizontal line should have been graded downhill so the unpumped water drains out by gravity.

 

[plowking]

You should have drilled a weep hole in the check valve on new pump so it could drain back into tank. New pumps like Liberty pumps have a drain back in base of pump but check valve needs weep hole as well. I clean septic systems I lift the float to run pump to see if weep hole is visible and not plugged with debris.On older septic the weep hole is visible when pump is on but newer septics the inspector has weep hole drilled inside of check valve. It is drilled thru the flap. The installer writes weep hole in check valve with permanent marker so I know its there. Weep hole is usually a eighth or quarter inch hole. You could drill a hole into side of pipe if it is allowed. . Pipe should have pitch all the way to pump chamber so it won't freeze if weep hole does its job .A sagging pipe outside of tank can help it freeze .Some lines are buried with ridged insulation on top but yours is an open system so it wouldn't work for exposed line.