This weekend I am running a new water line to the barn. The water line exits the pump room about 12″ above the slab, through the basement concrete wall to a three foot wide passage 20 feet along a 8 foot high retaining wall. I can not excavate the footing of the retaing wall down 24 inches to the frost line. Do I use pipe insulation protected by 4 inch pvc pipe? Do I use heavy wall copper pipe and heat tape (that can fail)? I plan on using black poly 160 psi and a bed of sand for the line that can be buried down 24 inches. I did search the achives.
Thanks guys in advance.
Replies
Put some rigid foam(couple of inches) over the top extending the width of the trench if narrow or 16 inches or what ever you have, then back fill. Sleeve the pipe as well so you can water jet it with hot water if it freezes.
Don't shovel the snow when it falls as the snow will help it the cold snaps from freezing deep.
good luck
rob
An inch of foam is roughly equivelant to a foot of soil. Its protective zone tapers at about a 45* angle inwards, like an upside down pyramid. The point of the pyramid must extend below the true frost line to give any protection to a pipe, but it's best to have half the pyramid below it.
Since the OP 's frostline is 24" below his waterline, IMO, he should use at a minimum, a full 4' wide, 2" thick foam right above it. Personally, I would use 2 1/2" foam and put 1" pieces on each side before placing the sand bed.SamTA Pragmatic Classical Liberal, aka Libertarian.
I'm always right! Except when I'm not.
Generally, when we can't keep a water hose below the frost line throughout its entire run, we place a specially made heating cable right inside the hose itself. This is very common with water supply lines coming from lakes. Most rural plumbers in cold climates will carry this type of cable and the thermostatic control units to drive them. Pyrotenax is one brand.
A cable less than 60 feet long will usually run on 120vac; anything longer than that will require 240v. These 'hot wires' are moderately expensive; a 160-foot wire with control box will run between $750 and a thou.
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