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.

 

[randyt]

many times we drill a small hole in the riser pipe coming out of the pump but this is only needed if there is a check valve. If there is a check valve when the pump shut off, water stays in teh pipe because the check valve will not allow it to drain back.

the hole is drilled above the check or simply remove the check valve.

 

[jgab]

many times we drill a small hole in the riser pipe coming out of the pump but this is only needed if there is a check valve. If there is a check valve when the pump shut off, water stays in teh pipe because the check valve will not allow it to drain back.

the hole is drilled above the check or simply remove the check valve.

I just checked the invoice and there is a check value on the invoice and assuming that's the problem. Not knowing anything about pumps (this particular one is a Zoeller) I'm assuming every pump designed for a septic tank can operate without a check valve?

 

[randyt]

I never install a check valve on a dosing tank pump, that is the problem. The check valve will not allow the water to drain back into the tank so it freezes. Also the float needs to be adjusted properly so the pump don't short cycle. It should run on a long cycle so when the pump shuts off and the water drains back it doesn't activate the float.

 

[jgab]

I never install a check valve on a dosing tank pump, that is the problem. The check valve will not allow the water to drain back into the tank so it freezes. Also the float needs to be adjusted properly so the pump don't short cycle. It should run on a long cycle so when the pump shuts off and the water drains back it doesn't activate the float.

OK, that makes sense thanks. This particular pump set up runs on a shorter cycle than the previous one - it engages on about 1/3 of a normal sized bathtub of water. My guess is the plumber that helped us out was not familiar with the operation of this type of system and the operation of it.

 

[randyt]

it don't sound like they were. it seems to me it is engaging way to soon. that and a check valve is the problem

 

[jgab]

it don't sound like they were. it seems to me it is engaging way to soon. that and a check valve is the problem

Thanks for your help, I'll attempt to get them to come back out and fix it.

 

[randyt]

good luck

 

[Tirediron]

Jgab, I am in rural western Canada also, wind can play a factor in open discharge systems, along with frost penetration, Most likely the check valve and short cycle as mentioned by randyt are the cause, any exposed pipe except for the last foot or so of the discharge could also be insulated, and if I was setting up a i would include a vacuum breaker to let the discharge empty rapidly when the pump stops,

 

[jgab]

Jgab, I am in rural western Canada also, wind can play a factor in open discharge systems, along with frost penetration, Most likely the check valve and short cycle as mentioned by randyt are the cause, any exposed pipe except for the last foot or so of the discharge could also be insulated, and if I was setting up a i would include a vacuum breaker to let the discharge empty rapidly when the pump stops,

You would do this rather than having a hole in the discharge pipe in order for the water to drain back out of the discharge pipe?

 

[randyt]

it will drain back through the pump with hole or not.

 

[Aerindel]

With my parents system, I have drilled holes in both the tank, between the pump and the discharge inside the second tank, and at the end of the pipes before they rise up so everything can drain out when the pump is off.

This has the added benefit of when the pump is running, the 3/16ths drain hole I made in the pipe within the second tank, sprays back down into the tank and aerates it.

 

[Tirediron]

the advantage of a vacuum breaker is the discharge can maintain a faster drain speed, rather than the gurgle that happens when the pump stops and the siphon action splits the flow. a drain hole in the tank is also a good plan, as well as removing the check valve and setting the longest cycle possible.