Septic tank to drain-field

[foggy1111]

Any septic / drain-field contractors out there from a northern climate??

I'm having a new home built.....and it's in Northern MN where it gets cold and the frost can go pretty deep. Friday they installed the septic tank and ran a pump-forced drain-field line to the drain-field. All is good.....EXCEPT.....I have a second garage building with perimeter foam insulation about two feet deep around this second garage building (my heated shop - which is being built at the same time). The plumber put the pipe on TOP of the 2" rigid foam insulation which insulates the foundation perimeter.

Will the 2" foam insulation, under the pipe, promote freezing of the pipe? (It seems to me the pipe no longer has the earth's core to provide warmth.)

 

[CalG]

True,

Put more insulation over the pipe!

 

[Raspy]

It's hard to visualize from the description. But if it's the line from the septic tank to the leach field, it will be sloped and empty except when draining to the field, so it won't freeze. Also if it was run another way it might have had too much slope initially and had to come back up, depending on your arrangement. A constant slope of about 1/4" or 3/8" per foot is best. You could go more after the septic tank because there is no solids there.

My main line from the house to the septic tank is only a few inches down in places and we freeze to at least a 18" in the winter. Never a problem.

 

[plowking]

If it is a pump forced drainline. Then you should have a purge or weep hole drilled in the forced main so the pipe can drain back and not freeze. I have seen the line freeze at the velocity tee in the distribution box at end of leachfield. We can get freezing lines from lack of snowcover to keep ground insulted. plowking

 

[foggy1111]

I guess one way or another my pipe from the septic to the drain-field is going to lay in frozen ground. I thought perhaps the foam under that pipe could contribute to a freeze-up. The pipe back-drains to the septic after it purges to the drain field.......and other areas of this pipe lay in frozen ground too (without insulation under it). Time will tell.

 

[plowking]

If it hasn't been backfilled yet,you could lay 2 foot strips of ridgid foundation insulation over it. Don't know about the insulation under it being a problem or not. plowking