Installing conduit for fiber optic cable with water/ww const. project

[shawnpac]

Hello -

I am working on a water/wastewater project for a small municipality. the project entails design and construction of appx 1 mile of water main and 3 miles of sanitary gravity/force main and 2 lift stations.

our plans are 90% complete.

yesterday, we had a meeting with the city in which they asked us to design 2 ea 6" conduits for future fiber optic cables (200-300 strand, appx 1.5" diameter).

The city's IT director has no construction standards for conduit, and basically no idea of what exactly he wants. I have no background in conduit design - so I'm doing research.

One of the biggest challenges I am facing is that our water and sanitary lines have numerous crossings of oil/gas/petroleum pipelines, a flood control ditch, and an interstate. Our utility crossings are all cased and called for "augered hole" type construction. The city has asked if it is possible to run conduits "clustered" in the same casing to save on augering costs (and because the pipeline crossings are so tight in places). The city has indicated that we can step down to smaller conduits for our cased crossings if required due to spacing within the casing.

If you have experience with these type of challenges - I'd love to hear from you.

 

[JedClampett]

Never done it, but I've observed it done in our City. It seems there are a lot of manholes for fiber. There would be a run of conduit, then five manholes in close proximity. Now this was a major fiber effort, so there were probably several independent conduits (each requiring independent access), but make sure you have that decided.

 

[bimr]

Maybe this link will help you:

http://www.udevices.com/pdf/conduit-in-casing.pdf

 

[civilman72]

First, 6" conduit seems excessive for a 1.5" line. Utilties around here require no larger than a 4" conduit.

Secondly, based on the Town's limited expertise in this area, I think you should contact a design engineer from the fiber optic cable company and pick their brain on all the items you need to consider (i.e. as mentioned above manhole requirements may be something you need to incorporate into your design). Also, as an example, phone and electric lines can cause issues if they are installed too close together (within 1'). So you need to have a sound understanding of what future utilities may be placed in these conduits, and their possible conflicts, prior to determining how close you can place these two conduits to each other and to other existing/proposed utilities. Hopefully someone from the fiber optic company can give you some more design details.

Installing clustered casings is a fairly standard practice, but again you need to plan for the required separation between the utilities.

 

[bimr]

NEC has no recommended separation distances for HV, MV, LV and communication/control conduits in underground duct banks. There are no industry standards or guidelines that recommend separation.

Good practice is to put the LV control and communications in RGS conduit or run them in armored cable. Keep at least 12" separation between high current power cables and control cables. You are probably not going to be working with high current power cable applications anyway.

Good practice is to use different duct bank and manhole systems for MV cable (4.16 kV and up) and 600 V and control/communications systems.

Reference the link for further details to get you started:

http://www.udevices.com/pdf/conduit-in-casing.pdf

 

[bimr]

http://www.leesupply.com/TechLibrary/PP 804.pdf

 

[StephenA]

This company makes conduits suitable for blowing the Fibre Optic cables (FOC) through with air. We have been told that distances of 5000m are possible. The FOC is just the strand and does not need the armouring etc.

http://www.wavin.com/master/master....ocument&middleTemplateName=oc_middle_content.

Stephen Argles
Land & Marine

http://www.landandmarine.com