Min. Clearances for Utility Crossings 1

[cieg22]

I'm involved in a project, where an engineer wants to install a new storm pipe in a nest of existing utilities. The new pipe would cross 6" above an existing duct bank (no idea how many volts it's carrying) and an existing water main, and it would cross 8" below an existing gas line.
I'm trying to find standards on the minimum allowable clearances for crossings. The NEC didn't seem to have anything regarding the ductbank (or maybe I missed it), and I'm not sure where else to look. Thanks!

 

[dik]

Check with the utilities affected...

Dik

 

[cieg22]

Thanks. Unfortunately, this is an "emergency", and there's not much time to do that.
Appreciate your help, and I agree that would be the best thing to do.

 

[jgailla]

It'll be more of an emergency when the gas utility makes you take everything out.

 

[mk3223]

I had buried pipe crossing about 2 inches gap over existing pipes. Added styrofoam in between to ensure that no direct load on the duct bank or pipe.

 

[Spartan5]

It'll be more of an emergency when the gas utility makes you take everything out.

Depending on whose right-of-way it is, licensing agreements, easements, etc.; the onus may be on the gas utility to take everything out.

Similarly, the clearances are likely set by the owner of the property on which the utilities run. Are these public or private?

 

[cieg22]

Public. The storm pipe would go under a 4" gas main, with about 8" of clearance.

 

[cieg22]

Everyone, thanks for your help!

 

[BigInch]

Gas and oil pipelines need a minimum clearance of 12" to ANYTHING.
Crossings with electric cables, underground or overhead, need to be as near perpendicular as possible and should never run parallel in close proximity.

Check in with your state's ONE CALL SYSTEM before beginning excavation work near any pipeline ... or buired electric cable.

Gas companies normally will require their rep/inspector to be present during any excavation near their pipelines. Convince them that it's an emergency.



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[oldestguy]

In some areas it is leaglly required for you to check out the utilities if you are anywhere near them.

 

[cieg22]

BigInch, can you give me a standard to cite?

 

[Spartan5]

How large of a storm drain are we talking?

Have you considered using elliptical pipe, or 2 smaller pipes to get you the clearance you need? If thick walled reinforced concrete pipe is being used, could you use PVC instead? That could get you upwards of four additional inches of clearance, top and bottom.

 

[oldestguy]

cig22 here is just one.

http://www.oconomowoc-wi.gov/DocumentCenter/View/3177

 

[cvg]

Southwest Gas 12 inches from gas lines (page 5)

https://www.swgas.com/1409181734392/Excavator-Booklet_2016_English_FINAL.pdf

12 inch minimum separation between wet and dry utilities in Phoenix (page 7)

https://www.phoenix.gov/streetssite/Documents/107528.pdf

 

[beej67]

From experience, when dealing with storm drains of that tight a clearance, make sure you take pipe thickness into account. Civil designs for storm drain are based on the interior dimensions of the pipe, not the exterior.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[BigInch]

Yes, the references are ASME B31.4 & B31.8 which state the 12" clearance for liquid hydrocarbon and gas pipelines, respectively. The legal requirements in the USA for federally regulated pipelines are (the 2002 edition of those documents) namely, the Code of Federal Regulations Title 49 Parts 192 and 195. Distribution company gas pipelines commonly found in city works will not usually be federally regulated, so they won't actually be covered under the CFRs, but that wouldn't necessarily be an excuse for not following customary practices established by precedence under USA federal law, hence Southwest Gas' 12" clear reguirement that was mentioned by cvg above.

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