need to trench for a water line.

Hey Terry,
I'm in Maine and I need to trench for a water line. I'm using 1" black pipe from the lake to the house. I've heard in the past the frost line is 4' and if you trench near a tree line it can be 3' deep. (true or faulse?)

Also if I run the black pipe through 2" white PVC do I need to go as deep as 4'

I was going to lay 2" foam insulation on the bottom of the trench,lay the white PVC on top cover with 2" of 1/2" crusher dust and back fill with gravel.

by doing this can I stay with in 2 to 3 feet deep?

Thanks
Eric

I can't answer all of your questions, but I can tell you that insulation won't do any good. Insulation does not provide heat. It slows heat transfer, but water at rest in an insulated pipe with frozen ground all around will freeze. In my opinion, you should trench 5 or 6 feet to provide a margin of error.

If plumbing code in your local area is four feet of cover, then that's what you will need.

The size of the pipe doesn't matter.
And insulation isn't going to help either.
If the ground freezes, the pipe will freeze.

Gary's from Yakima, where the ground freezes deeper then in the Seattle area.

Since we are surrounded by water here, we can get by with two feet of cover.
Parts of Idaho require five feet.

And yes, the worst part is always the trench.

Terry is correct... you must stay at or below the required depth for water lines in your area or you will be redoing the line in the middle of winter...I have never heard of tree roots traping heat so stay at the 4 foot depth...sleeving the line will keep rocks from causing problems ...

Personaly I use 4" corragated black dranige pipe and just backfill with what was dug out..if you sleeve the line you won't need any pea gravel, sand, or anything...


how long is the run...

pipe

Putting the pipe inside a sleeve will not make it any warmer, so it will freeze when the temperature is low enough.

not the best links, but. . .

"Tree roots in the ground can reach below the frost line and continue the metabolic work of keeping the tree alive even after the top seems to be frozen." so I guess trees do give off heat.

"Typically, the below-ground temperature will be less variable from season to season than the air temperature, with temperatures tending to increase with depth. Thus, if the mean annual air temperature is only slightly below 0 °C (32 °F), permafrost will form only in spots that are sheltered — usually with a northerly aspect. This creates what is known as discontinuous permafrost. Usually, permafrost will remain discontinuous in a climate where the mean annual soil surface temperature is between −5 and 0 °C (23 to 32 °F). In the moist-wintered areas mentioned before, there may not be even discontinuous permafrost down to −2 °C. Discontinuous permafrost is often further divided into extensive discontinuous permafrost, where permafrost covers between 50 and 90 percent of the landscape and is usually found in areas with mean annual temperatures between −2˚ and −4˚C (28˚ and 25˚ F), and sporadic permafrost, where permafrost cover is less than 50 percent of the landscape and typically occurs at mean annual temperatures between 0˚ and −2˚C (32˚ and 28˚F)."

"Apparently 50-55 Fahrenheit at about 4 feet is considered average,
however over sufficient time periods (years) the temperature can
settle at lower (or higher) temperatures. "Permafrost" which
apparently covers about 20% of the earths surface is soil at or below
freezing and over sufficient time periods can extend to hundreds of
metres below the surface."

Are you near Crocker Mtn?
http://www.udel.edu/Geography/udpg/people/walegur.html

Or else go shallow and pass very heavy elec. current through the pipe whenever it freezes. You have a welding machine?

freeze

I do not think he lives in an area which has "permafrost", and if you recommend a welder to thaw the line, you must have missed the part where he says he is using "black pipe", which is probably plastic PE and thus non conductive.

digging too close to a tree will kill it. You have to check the kind of tree and what kind of root system it has to know how close you can safely dig. Some trees are more tolorant of root damage than others.

Insulation under the line will prevent heat from the earth from getting to the pipe. Insulation above the pipe would help keep the pipe from the cold but, not for long because the cold will go around it and then under it.

160 psi or higher rated PE pipe does not need a conduit. Just keep sharp rocks off of it or from laying it on any and back fill the trench.