# Is this normal?



## Bearded Wonder (Jan 21, 2011)

So we are starting a new house, and part of the prep is to replace 140' of 4" sewer line which was installed improperly 7 years ago. It had developed a belly in it from settling down, that made it drain poorly. 

The owner specified that he wanted the old pipe dug out, then 3" of chat/gravel laid, then the pipe which was to run exactly straight at the correct slope (no bellies or sags period), then cover with 3" of chat. 

After that, we back filled with the soil we dug out (his soil is basically select fill), and it had to be compacted to 95% compaction or better. 

I had read the specs, and basically thought ok no prob, we'll just pack it in good. However, the owner is a Geotechnical engineer, and he had the soil tested. Then he brought out a machine with radioactive material (wtf????) on it which would test the compaction we were achieving. We were only getting 90ish percent, so we had to keep packing. Turns out we can only do basically a 2" lift then pack the sh*t out of it, then do another lift (trench averages 3'-4' deep). So three guys on jumping jacks, another 3 on shovels were on it all day today, and more tomorrow. 

We'll get it done, owner is happy. None of us, the plumber, me, the digging crew, have ever heard of this, despite having installed many sewer lines between us. 

There is a portion of the trench which will be in under the carport and driveway, but this still seems incredibly overkill. Is this at all normal for residential sewer lines? 

Thx.


----------



## Dan_Watson (Mar 1, 2008)

Switch to a plate/larger vibrator or a roller instead of the jumping jack.


----------



## Alchemy (Mar 4, 2015)

No that is not standard practice where I'm at which is just 3 hours north of you in oklahoma. I assume the HO didn't wan the same problems he experienced previously, but that is a bit much. Rent a wireless trench compactor and be done...


----------



## tgeb (Feb 9, 2006)

Not typical on residential work, but common on commercial type work. 

That was a nuclear density gauge...Quickest way to confirm compaction results.


----------



## AccurateCut (Mar 20, 2015)

Go engineer need say more


----------



## dayexco (Mar 4, 2006)

was this ditch in the landscaping, or under a paved surface?


----------



## mattg2448 (Jan 26, 2015)

Definitely common in commercial, typically a plate compactor on a 160 will do a 4ft lift pretty easy for us, some times they will make us do 2ft lifts but not normally. Only time we Hoepack to spec on residential is under any driveways, buildings, sidewalks, after that we get as close as possible and inspector is happy.


----------



## slowsol (Aug 27, 2005)

If that were commercial work you'd be filling the trench to grade with stone under all paved areas. 


Sent from my iPhone using Tapatalk


----------



## mattg2448 (Jan 26, 2015)

Sand is in spec here.


----------



## Moxley-Kidwell (Jan 28, 2011)

It's pretty typical. Have him check the moisture with the gauge and if he knows what he is doing he should be able to tell you the optimum moisture level for the soil in question. You could be there a while if it isn't close and never get compaction. You should be fine with jumping jacks and should be able to do at least 6" at a time, something doesn't add up. Trench roller might help though.


----------



## griz (Nov 26, 2009)

What's chat?

Pipe usually bedded in sand & back filled.

Not completely uncommon to see a nuke gauge in residential.


----------



## Bearded Wonder (Jan 21, 2011)

Moxley-Kidwell said:


> It's pretty typical. Have him check the moisture with the gauge and if he knows what he is doing he should be able to tell you the optimum moisture level for the soil in question. You could be there a while if it isn't close and never get compaction. You should be fine with jumping jacks and should be able to do at least 6" at a time, something doesn't add up. Trench roller might help though.


He knows the optimum moisture range, and some areas are a little over, and those areas are harder to pack, but we have got to 95% or more everywhere. 

If I had to do it again I would have got a roller or something bigger than jumping jacks.


----------



## Bearded Wonder (Jan 21, 2011)

griz said:


> What's chat?
> 
> Pipe usually bedded in sand & back filled.
> 
> Not completely uncommon to see a nuke gauge in residential.


Chat is a mining byproduct (I think) that is basically 1/2" and smaller chipped rock with some pretty fine granules in it, so it's pretty stable. That's off the top of my head, but something like that...


----------



## dayexco (Mar 4, 2006)

What I never understood, is a homeowner will take the lowest bid on things they cannot see, to have the extra money in their budget for carpets, drapes, stainless steel appliances only to have problems with water, sewer lines. ..their $20k worth of landscaping and paved surfaces settle, fail because of improper installation. 

Sent from my SCH-I545 using Tapatalk


----------



## rino1494 (Jan 31, 2006)

Not normal for residential, but you are working for an engineer, nuff said.

BTW... did he provide you with a soils report before you bid? If not then I would tell him that it will cost extra for the additional time it is taking to achieve compaction that meets his standards. 

This all depends on your contract.


----------



## Bearded Wonder (Jan 21, 2011)

rino1494 said:


> Not normal for residential, but you are working for an engineer, nuff said.
> 
> BTW... did he provide you with a soils report before you bid? If not then I would tell him that it will cost extra for the additional time it is taking to achieve compaction that meets his standards.
> 
> This all depends on your contract.


We had all the info when we quoted it, and we came out ok on it. The only place we missed it on was- in the contract it stated to backfill with MAXIMUM of 9" lifts. We assumed (incorrectly) that we would do full 9" lifts. Problem was we quickly learned we couldn't do much more than a 2" lift, if we were packing with jumping jacks (and we were), and get the 95% compaction. 

So it took longer than we thought and more guys. Luckily we had budgeted a PITA factor, and that took care of the extra. The plumber had to eat some extra labor costs, but not too bad.


----------



## mattg2448 (Jan 26, 2015)

What kind of material? Sand? Clay?


----------



## jhark123 (Aug 26, 2008)

This is a learning experience. Don't bid work when they want you to achieve a compaction % with native material. That is T&M only work imho.

If they want 95% compaction, they pay for 5/8 minus if I am doing it on a bid.


----------



## jhark123 (Aug 26, 2008)

double tap


----------



## Bearded Wonder (Jan 21, 2011)

It was the existing soil, but according to the owner, it's basically a quality select fill. The PI (the owner had to educate me on this, has to do with plasticity verses liquidity or some such) is about perfect he says. So basically a good mix of sand and clay if I'm not mistaken.


----------



## jhark123 (Aug 26, 2008)

Well, the owner pulled the wool over your eyes. Select fill does not take 2" lifts to achieve 95% with jumping jacks. I usually do 18-24" lifts with 5/8 minus.


----------



## peteo (Jan 8, 2011)

Bearded Wonder said:


> It was the existing soil, but according to the owner, it's basically a quality select fill. The PI (the owner had to educate me on this, has to do with plasticity verses liquidity or some such) is about perfect he says. So basically a good mix of sand and clay if I'm not mistaken.


Sounds like your fill has way too much organic material in it. With select fill you should be able to hammer down 6-8" lifts with a jumping jack with no problems. I'd say your client was trying to get away with being cheap and not using a quality fill


----------



## Dozerman56 (Dec 11, 2009)

I bid specification work constantly here in NC and pipe backfill compaction is typically 95% under pavement or buildings, 90% or less under green areas


----------

