how much sand to backfill waterline trench?

[HeLa]

how deep of a sand bed above/below the tubing do you all backfill with, to protect a buried poly water line? thanks.

 

[JRobyn]

I used - zero - . Was careful to avoid any rocks from the trench spoils when I backfilled, at least until I got near the top. I may be sorry later! Five years so far; all good.

- Jay

 

[HeLa]

I used - zero - . Was careful to avoid any rocks from the trench spoils when I backfilled, at least until I got near the top. I may be sorry later! Five years so far; all good.

- Jay

fair enough. with rocks < 4" i don't technically *have* to use sand, but i've got time to order it and it seems like cheap insurance.

 

[JRobyn]

You are absolutely right. A few inches under and few over (IMHO) would be plenty adequate, UNLESS you did have numerous large, sharp rocks that could easily push down through a few inches of sand. But that could only happen (IMHO) WHILE you were actually backfilling and could exert that kind of pressure DIRECTLY on any rocks. Once everything is completely backfilled, the soil and/or sand all around any rocks will distribute forces pretty evenly all around a rock and prevent any subsequent movement towards the waterline. To be really safe, with 4" rocks, put 5" over the line.

- Jay

 

[Billrog]

Lay the pipe loose in the ditch ( not tight or straight) this way when you back fill it won't be stretched and put 4 to 6" of sand on top before back filling.

 

[SirReal63]

Manufactured sand is cheap, I used about 4" under, several inches around and another 4" on top, then back filled. All of my water lines and electrical lines have been done this way, but we do have rocky soil.

 

[EddieWalker]

After I got out of the Marines, my first job was running a water truck. One of the jobs I would go to where jetting the sand around water lines. They would put an equal amount of sand all the way around the pipe. The trench would be a foot wide and they had a foot of sand on the bottom and another foot above the pipe. Since sand self compacts and settles with water, I would shove the end of the hose into the sand and run water into the ditch. You could see the sand level out and drop once it was saturated with water. Then the contractor would fill the ditch with dirt, compacting it with a jumping jack as it was filled. The city would test for compaction and then we where done.

For a smaller residential line, I would guess that 4 to six inches around the pipe should be plenty. The goal is to make sure nothing sharp gets next to the pipe and wears away at the side of it as the pipe moves in the ground. Crazy how much they move once buried, but it's why pipes break.

Eddie

 

[dmccarty]

When I back filled our water line, I put in about 6-12 inches of sand. Before filling with dirt, I put some flagging tape on top of the sand running the length of the trench to locate the pipe if someone digs in the trench. On purpose or otherwise.

Later,
Dan

 

[HeLa]

thanks all!

anyone have input on using screenings (stone dust)? when i called the quarry today they asked if i could substitute, as the screenings are 20%-30% cheaper. wondering if screenings are more abrasive and whether the fact that they compact is a good or bad thing. inputs appreciated.

 

[treefarmerguy]

I always put water and electrical lines in plastic pipe which has been snaked through six inch corrugated drain pipe. Cheap insurance if i ever have to replace a line. Also backfill with what was taken out minus the rocks.