Depth of underground lines?

[salecker]

Hi All
I'm hoping to get my underground lines in this weekend.
My plane was to have 4 1" lines buryed 4' underground,with aprox 6" closed cell insulation around each line.
I have 110 ft between bldgs,and the lines will run under a driveway.
The ground is hard clay.I plan on lining the trench with plastic.
Any other tips,or things i may have missed?
Thanks for the replys
Thomas

 

[in hot water]

what is your water table? With clay and a plastic liner, ground water will not escape. Even with spray foam I suspect water in the trench will get some of the heat. It's hard to completely en-capsule the tubes in a foam block.

I much prefer the pex inside a sealed PVC conduit, then insulate around that. This assures 100% waterproof piping, and allows you to replace the line(s) if ever needed.

Remember pex expands and moves a lot as the temperature in the pipe swing. It could go from ground temperature to 180F or more in a short time. That could equate to a couple inches of expansion movement over your length. So the tube is always trying to move inside the spray foam block. It has to expand somewhere, hopefully not out the side of the foam.

hr

 

[woodsmaster]

Could put sand in the trench under the pex to help draining. I would at least put the pex in condiut on the part that's under the driveway.

 

[Former Farmer]

Under the driveway, I would go 6 feet deep. If you don't have snow cover and drive over the driveway a lot, you will drive the frost deep into the ground. I remember 1 year when I was young. We had a week of temperatures below 0*F for an entire week (including the days). We did not have much snow cover that winter and the driveway was bare. About 2 weeks after the cold snap broke, our water line going out to the barn froze solid. Thank goodness it was a copper line and we could hook a welder up to the line and thaw it out.

Putting sand under the pex lines in the trench is a good idea if the water has somewhere to drain to. You could pitch your trench to the house and allow the water to flow towards the house foundation and have the drain tile take the water to your sump pump and pump it back away from your house hopefully in the opposite direction.

 

[btuser]

I like the pex-in-pvc idea. Don't underestimate the movement of the pex when it heats up. The foam won't stop it. 4" drain pipe Non-perforated) would be pretty cheap. You could lay 2, one for supply and one for return. Foam the ends of the pipe and the air buffer will work as well (if not better) than the foam.

Of course, PVC moves around when it heats up too! Maybe a couple expansion joints? Those are expensive, however in the larger diameter

 

[juddspaintballs]

Interesting idea. A supply and return drain tile encased in expanded foam. I may just use that idea with 3" drain tile.

 

[Tony H]

You can use inexpensive water pipe as your outside pipe with the pex inside that . The main idea is to NOT use jointed pvc pipe to avoid water entering the pipe should the joint leak. One practice used around here in N illinois is cutting pieces of blue insulation board and forming a box around the pipes then spraying in expanding foam. I would caution against pitching the pipe to drain toward toward your foundation This is a really bad idea in a heavy storm you could be pushing 1000's of gallons of water in to flood your basement. Pitch the pipe away from the house and do the same on the other end if possible then somewhere at the low point between excavate and dump in a bunch of gravel to act as your drain field you could even do this a couple different spots, 10-20 feet away from either side of the driveway might work.

 

[salecker]

Hi
So things didn't work out on the lines,rained all weekend and no show on the foamers.Glad i didn't have the ditch dug.
Anyhow thanks for all the coments and suggestions.We are about 200 ft to the water table,so no worrys on water from underneth.Like i said it's 100% clay so once it's backfilled there is little chance of water from the surface.the house side is higher and under cover of a deck which has a roof over it.
I did get the stand built for my 2x500 gal propane storage tanks,they will be standing on end.Now i have to get the tanks ready with a few more outlets,am using weld on fittings.I have a 9' door to get through and will have a hieght of 8'7"when finised with out the foam.Will have to foam it inside my boiler room.
So hopefully the weather and foamers coperate this week.
Thanks Thomas

 

[salecker]

So
Got the ditch dug about 10 days ago and lines ready for the foamers to be here on the weekend,then monday,then tuesday.Didn't here from them on tues,started leaning mesages on tues,wendsday and finally gave up on that company.Finally got some to come out yesterday,they didn't show up till late afternoon,then their gun was plugged,extra gun had wrong air fitting,finally got spraying finished up real late,they want to do a final pass this morning.
Unfortanatly the weather went to crap and we woke up to 2" of snow,had my 110' of ditch covered in a tent,but there go my hopes of doing a nice clean job ,with the snow and clay backfilling is going to be messy
I was hoping for a story book install,Murphy likes to work overtime around me,so now it may end up more like a horror story,Probly will be ok seeing the pex is all foamed in,just really wanted to avoid the mess of wet clay,was hoping to have the yard retuned to pre digging condition in dry weater
Time to knock the snow off the tarps again.
Thomas