Trenching - multiple utilities

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goldstar

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I'm working on a large residential project where a HO has a barn, a greenhouse and a pool cabana on his property. He would like to have electric, water and natural gas to each of these out-lying buildings. When we asked the building dept whether we can install all three utilities in the same they suggested we contact the State. So I did, and these were the questions and situations I posed :
  • Can we can run all 3 utility services in the same trench.
  • If not, would you please give me some guidance as to what would be the correct installation in these cases?
  • I know electric in PVC has to be down 18" below grade but I'm not sure about the other services.
  • I also plan to have a tracer ribbon installed about 12" above the electrical conduits.
  • Are any other types of identifying ribbons required for the other services ?
These were the answer(s) I received :

Good morning,

I am including in this response the plumbing subcode official for Code Assistance, to answer your plumbing questions. Expect a follow up email.

From an electrical standpoint, the NEC does not prohibit other utilities from sharing the same trench, it would just be a matter of managing all the various burial depths.

Installing a warning ribbon is a good idea, although it is not required. No warning tape is required for the work you are proposing, since they are not service conductors, but would be defined as feeders.
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This was the answer from the plumbing official :

Burial depths and separation shall be as cited in the 2021 NSPC 10.6 and 13.1.3and the 2021 IFGC/IRC 404.12/G2415.12
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Why can't you get simple answers to simple questions ? If anyone knows th answers to these questions would you please post it here ? Thanks.
 
If these are customer owned utilities, after the meters, then they can all be in the same trench. Barring any local.
The water line needs to be deep enough to prevent freezing. 54" IIRC.

Ron
 
Thanks for your replies. I checked with the EI in this town, who just so happens to be a friend of mine and in my contractors association, and for the most part he agrees with both of you. The water service utility from the street to the house has to be down below the frost line. In this area that is 42". However, he said that once you are on the property the burial depths to out-lying areas do not matter because they are considered feeders. Normally you would blow out the water line(s) before the winter anyway. I'm going to check with the BI anyway just to make sure there aren't any obscure Codes that we have to comply with.

I've always been a proponent of 3rd party inspections but my major gripe with inspections is that they won't tell you how to do a job correctly BUT they sure will tell you when you've done it wrong !!!
 
On a project in Bergen County NJ about 15 years ago, my client hired his own plumber and electrician for the project. He is a home developer and these were his subs. He was building his new home at the same time too.
Gas, electric and water all ran in the same trench to the pool equipment at the same depth (I think was probably 2'). The plumbers were told by the inspector that the water line had a minimum distance from the other utilities. They also had to secure it to keep it from moving. First and only time I have heard of this.

We have historically run all 3 utilities in a trench without any issues from inspectors. Most times the pool piping intersects with these utilities too near the pool equipment.
 
they can be in the same trench. coordination between trades for lateral separation is recommended. when I share trenches, typically the utility or plumbing contractor will dig and lay water first, backfill 12", then gas, backfill 12-18". We will then install electrical and complete the backfill and compaction of the trench. All laterally separated and marked w/ ribbon or tracer.
 
Nothing wrong with everything in the same trench. Bury the water at the bottom, backfill a little and run the rest on top of that.
 
goldstar said:
Why can't you get simple answers to simple questions ?
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As far as the code references you posted:

NJ uses an oddball plumbing code, the NSPC. You can view it online here: https://epubs.iapmo.org/NSPC/NJ2021/

Section 10.6 is on viewer page 148, book page 137. It doesn't address your burial depth question, but as other have said that goes by frost line depth. The only thing really relevant to your question is that the potable water supply has to be 1 foot horizontally from any non-potable water supply and any sewer.

As to the gas burial depth, the answer is apparently 12" deep. You can read the code references here (they say the same thing):


Cheers, Wayne
 
While you're burying all that, I'd do another 1" conduit for fiber between those locations. If they want all that infrastructure, they're going to want Internet as well.

What about sewer? If they have a pool house, isn't there going to be a bathroom?
 
ActionDave said:
One ditch deep enough for the water and wide enough for whatever else, nothing stacked on top of anything else.

Why would you want to cut up the gas and electric to get down deep enough to repair the water line?
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Around here we throw in electrical, gas, our wife's [ouch] in the trench. 18 inches on residential properties.

Water needs 48 inches and as Action Dave said should in separate trench.

Warning tape is advised as long as it's install at least 12" above lines. Some lay it on top and by then it's too late with a machine.
 
I don't want to say the trench question is a stupid question, but...

Once the trench or trenches is/are backfilled, what difference does it make how many were dug? All that matters in the end is the separation underground.

Dig a 4ft wide trench, lay different items 3ft apart, then backfill. What's the difference in the end if you had dug two 1-foot wide trenches that are 3ft apart on center?

goldstar said:
This was the answer from the plumbing official
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Seems adequate. He gave you exacy references so you can educate yourself about the separation requirements. Then you can decide the most practical way to meet them.
 
jaggedben said:
Seems adequate. He gave you exacy references so you can educate yourself about the separation requirements. Then you can decide the most practical way to meet them.
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Adequate ??? Not hardly. Contrary to popular belief I'm an electrician, not a plumber or excavator. I don't have a copy of the 2021 NSPC 10.6 and 13.1.3 and the 2021 IFGC/IRC 404.12/G2415.12 handy. Why can't he just answer the SIMPLE questions I posed ?

I'm just trying to do the RIGHT job the FIRST time. As I've said before, many construction officials don't seem to want to tell you if you ARE doing the right job, but they CERTAINLY will tell you if you've done it WRONG and will cite the Code section(s).

Thank you all for your replies and opinions. I plan on meeting with the town's construction official either today or tomorrow. I'll post his/her comments when I find out.
 
Regardless of the codes and such, I can't see why anyone would put water in the same trench with anything....esPECIALLY on the bottom. If there is one utility that could develop a leak and need to be excavated in the near or extended future, it is the water. If I was the guy repairing the water line and it had soil then gas then soil then electrical on top of it.....I'd be pissed. And I'm sure glad our frost line is 18" and not 54"! Holy smokes.
 
4x4dually said:
Regardless of the codes and such, I can't see why anyone would put water in the same trench with anything....esPECIALLY on the bottom. If there is one utility that could develop a leak and need to be excavated in the near or extended future, it is the water. If I was the guy repairing the water line and it had soil then gas then soil then electrical on top of it.....I'd be pissed. And I'm sure glad our frost line is 18" and not 54"! Holy smokes.
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I still don't see what the issue with the "same trench" is. We had a job where due to utility requirements we needed three foot of separation from gas and other utilities. They dug a 6 ft wide trench and we put one on each side and one in the middle. All in the same trench.
 
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