Electrical PVC Conduit Backfill - Sand or no sand?

[dtbingle]

Finished with running electrical out to the garage and at the backfill stage. The majority of the material removed was softer clay. I wet a bunch of the clay into a soft mixture, put it in the trench, and almost 'squished' it underneath the conduit to make sure it was supported. After partially bedding the conduit with clay, it dawned on me that sand probably should have been used.

Is it required to drop sand/pea gravel to surround the conduit? Is it worth it to uncover the partially buried conduit and pour sand before backfill with the removed clay material?

 

[stikman56]

Wasn't required here in Washington. The schedule 40 we had to use is really strong stuff. If it's not code, I'd fill it with dirt.

 

[MagKarl]

For conduit I worry about larger rocks but am comfortable covering with dirt.

I'm more concerned with water and gas lines and bed those in sand.

Just my opinion.

 

[Strouty]

I like a bed of sand surrounding the conduits, but we deal with a lot of frost, even some at 48" (and deeper). Sand keeps the water drained around them and helps protect the conduit from rocks. Sand is also cheap.

 

[LXCam]

You only need to worry about it when one it's really rocky soil ^^^ or two if it's for the utility company and they require you pull a mandrel through it to confirm it maintains its concentricity. If it's large conduit 3"+ and you're pulling feeders through it then it might not be a bad idea, but even then if it flattens out a little bit it's not the end of the world normally. Schedule 40 is really robust, it's when you're using DB100/200 when you need to start paying attention.

 

[jives]

Just backfilled 60' of trench across my driveway. The excavated material had many large rocks. I backfilled and tamped about 6" of dirt -- no rocks/gravel -- around the conduit (2" PVC, Sch 40), then used my Wheel Horse tractor with a plow to backfill the rest. Driving over it tamps it down.

 

[dtbingle]

Got it. Sounds like there shouldn't really be a problem backfilling with the clay in my situation. 40' run of 1" pvc under a grass area with only foot traffic.

 

[dutchgray]

We always backfill with sand and most of the ground round here is clay. The main reason is it gives you or anyone else warning before they work the digger bucket through it later on, we use warning tapes buried a few inches above also.

 

[rburke65]

Did you run an extra conduit....or two?

 

[wyliesdiesels]

Did you run an extra conduit....or two?

great idea for communication circuits.

Also, drop some caution tape in the trench about 18" from the surface