Shallow Sewer Line

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woodsy
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Shallow Sewer Line

Post by woodsy » Sat Feb 03, 2018 11:51 am

My cabin sits on a slab and the sewer line where it comes out from the cabin is only 6" underground. It goes 40' to a holding tank. At the tank it is 24" to 36" underground not sure of exact depth. I haven't used this during the winter in the past but will be starting next year. I am concerned about the sewer line freezing, the cabin is in Northern Wisconsin. I am looking for options as to make this so the line doesn't freeze to see if I can do something myself before calling a professional.
I was thinking of maybe heat tape around the shallow end and insulating the entire run. Or digging it all deeper and using some sort of lift pump on the deep end to get it up to the tank, I don't even know if there is such a thing. This is a holding tank, not a septic tank.
I asked this question on another forum and was told by a plumber that sewer lines don't freeze which I can't believe. The only other solution from that forum was to insulate above ground, which I don't know would be enough to stop freezing. Anyway if anyone has some ideas I would really like to hear about them. Thank You


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Aaron
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Re: Shallow Sewer Line

Post by Aaron » Sat Feb 03, 2018 2:23 pm

Heh, I'm not sure what solution you'd have because it's well above the frost line which I would think would be dangerous because the earth freeze-thaw cycle could crush the pipe. But maybe shallow burial is a normal thing and that doesn't happen (as the plumber told you). I'm not sure. I'm only familiar with septic lines where those lines and tanks are below the frost line (usually 5 or 6 feet or so).

Maybe a good person to ask the question would be the waste hauler who empties the tank?

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Shannon
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Re: Shallow Sewer Line

Post by Shannon » Sat Feb 03, 2018 4:22 pm

Hmm this is a very good question if it were a short run I would be inclined to think you may be ok or to just protect it from freezing with some kind of surface insulation but on a long run like that I think most waste would freeze before it got to the tank and eventually build up enough to cause plugging or at least drainage issues. Are you sure of your depths? It seems like an awfully steep slope for that pipe to be on if it is only gravity movement. 1/4" of drop per foot is normal, if your depths at each end are correct then you have at least double that.
Is there other properties in your area that would have a similar set up? you could maybe talk to those owners to find out if there are issues?
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woodsy
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Re: Shallow Sewer Line

Post by woodsy » Sat Feb 03, 2018 6:19 pm

No, I am not sure of the depth at the tank end, I haven't taken the cover off to measure but I will in the spring. I have looked into a heater that you connect to the vent, but the cost is $1900 which I am trying to avoid. It seems like I probably should contact a local plumber that has dealt with these issues in the area and ask his advice in the spring. I was just trying to find some advice for a DIY project but this is probably something for a local professional. Thank You for your responses I do appreciate your it. Great job on your videos Shannon I refer to them often, Thanks again!

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Aaron
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Re: Shallow Sewer Line

Post by Aaron » Sat Feb 03, 2018 7:12 pm

My dad has lake cabin property in northern Wisc, and he consults with a plumber in town. They know from solid experience all the issues that are common to cabin dwellings. I would consult with a local plumber and your waste hauler. Definitely try to avoid that heater cost if at all possible, it might be totally unnecessary.

woodsy
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Re: Shallow Sewer Line

Post by woodsy » Fri Nov 23, 2018 8:26 am

Just an update what I finally ended up doing! I contacted area plumbers but only one responded. His feeling was he couldn't help me. I think if business was slower I would have gotten a different response. Anyway I ended up putting 3" rigid insulation over the entire surface, then I covered with leaves. I then ordered the $1900 septic heater and I have had no problems. There is an auto and manual mode on the heater. In auto mode if the tank temp. drops below 38 degrees it turns on. On really cold days, below zero, I plan on turning on the manual mode, when we are running water thru the sewer line. This was an expensive fix but it really came down to the only solution I had.

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A. Spruce
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Re: Shallow Sewer Line

Post by A. Spruce » Fri Nov 23, 2018 11:33 am

Thanks for the update.

As expensive as it was, the security in knowing that you won't have to deal with a frozen sewer line at the least opportune time is worth it.
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Shannon
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Re: Shallow Sewer Line

Post by Shannon » Fri Nov 23, 2018 5:07 pm

Glad you figured something out!
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