Recommended Backfill Material - New Sewer Line in Yard

[Paul E.]

I am running a new sewer line in my front yard. I've trenched 60' and now need to add some bedding material for the 4" pipe. Locally I can get sand, gravel, decomposed granite, pea gravel, and road base. Any reason to use one over the other?

The existing soil is 4-5 inches of top soil, then 20 inches of very sticky and heavy clay. A little bit of limestone towards the bottom of the trench.

 

[Jeff H Young]

Id probebly use what is there. but a foot of sand be nice. A side note , Id probebly turn with the sewer just past the end of walkway with a 22 or 45 as it looks like a 90 you have Id definately put a clean out in yard.

 

[Sponsor]

 

[Tuttles Revenge]

In our area we are required to use 5/8 minus crushed rock for backfill around sewer pipe.

 

[Paul E.]

In our area we are required to use 5/8 minus crushed rock for backfill around sewer pipe.

Looking at UPC 718.2, it states that "sewer piping shall be laid on a firm bed throughout its entire length, and such piping laid in made or filled-in ground shall be laid on a bed of approved materials and shall be properly supported as required by the authority having jurisdiction."

All the city inspection checklist says is, "Approved bedding/backfill material was used when installing piping underground." I used a sand bed in the interior of the house, and the inspector took no issue with it. Just wasn't sure if gravel or something else would be better outside.

Id probebly use what is there. but a foot of sand be nice. A side note , Id probebly turn with the sewer just past the end of walkway with a 22 or 45 as it looks like a 90 you have Id definately put a clean out in yard.

You have a sharp eye! That 90 at the end of the sidewalk is mostly due to the excavator bucket, the plan is to run the sewer line on a 45 underneath the remaining bit of sidewalk. I'll have to sketch my proposed clean out locations, and make sure I'm doing that right. They are required every 135 degrees of change, right?

 

[Jeff H Young]

trench is fairly shallow , we often just use the native soil , if you dont over excavate and your pipe is on solid ground or bed of sand should be ok . often use sand more than rock
yep 135 degrees max for the cleanouts

 

[Reach4]

Compact the lower layers as best you can. This could include pounding the dirt with a sledgehammer.

I recommend making at least the top 4 inches to be topsoil. Mound it up, You will need to discard some non-topsoil to fit the topsoil in.

 

[John Gayewski]

You should use clean rock. It makes a firm bed and doesn't need to be compacted. Then when you cover the pipe put whatever you'd like over it. Use something other than dirt for the first 12" so when the time comes to dig it up there is a warning layer before you hit the pipe.

Also tracer wire can be a life saver for people (or you) in the future.

 

[WorthFlorida]

Using gravel or sand will allow for an easier way to get a smooth slope to prevent any voids under the pipe. Any void under the pipe may eventually allow the pipe to sag. As you lay the pipe each section needs to be checked with a level for proper slope. Looking at it from above, it may look good but the eye can be fooled and a section might slope upward. Nice work anyway.

 

[Tuttles Revenge]

You should use clean rock. It makes a firm bed and doesn't need to be compacted. Then when you cover the pipe put whatever you'd like over it. Use something other than dirt for the first 12" so when the time comes to dig it up there is a warning layer before you hit the pipe.

Also tracer wire can be a life saver for people (or you) in the future.

We use the tracer / warning foil tape a foot over the top of exterior work.

 

[Jeff H Young]

Have done very little underground on single family home since 03 . We never ever put tracer on sewer back then . and almost allways back filled with the same soil that we removed big rocks or a lot of clay under driveways we would use sand. A 2 ft deep trench way less concern than 4 foot or 6 foot especialy in the yard but compaction can be issue.
I definately like the tracer wire and foil marker but maybe we were way careless or our conditions are differant nothing special about that trench to me 2 ft deep basicaly no special back fill in a lawn in my area

 

[Paul E.]

Great idea on the tracer wire/foil tape, I'll add some foil tape 12" above the buried line.

Reached out to my inspector, they had no preference on the bedding material, said native soil, sand, or gravel are all fine, just can't have any large rocks. I am leaning towards the decomposed granite 1/4 minus. Would the gravel benefit from being compacted with a jumping jack or similar?

The image below shows the two cleanouts I have planned, indicated by red dots. Is the second cleanout necessary? My fittings add up to 135°, so I think it is. The pipe jogs to avoid a tree in the middle of the yard.

Thank you for all the tips and help so far!

 

[Tuttles Revenge]

That small of gravel will compact about 3%. If you're placing it on undisturbed soil then you could accomplish that with a tamper or plate compactor. A jumping jack will disturb the gravel as you move from my experience. And I believe you need at least a foot of material over the top of your pipe before using a mechanical compactor on top of it.

You will never regret having extra cleanouts installed in a sewer.

 

[Jeff H Young]

Paul , the clean out next to the 90 I do a little differant instead of the 90 I put a combi on its side and put the 90 on the uphill side pointed up for cleanout. it has advantage being a little closer to the house. I just think its a better way its how I always do it its usually the way I see it drawn on isometrics or plans .