HDD Water Mains - Should Designer Specify Joint Restraints? 5

[TJH2161]

I'm the engineer for a local water utility company in Louisiana. When we perform waterline replacements/installations, many times we are running a line in a heavily populated area, so we have to HDD the waterline to avoid conflicts. We run C-900 everywheres now. For any called out bore, we currently require internally restrained joint (IRJ) pipe for the length of the bore. Every where's else where it is open cut, we use standard slip joint C-900 pipe and required pipe to pipe restraints where needed due to offsets/dead ends.

My question is, should we be specifying if IRJ pipe is req'd for these bores? Or should be put that on the contractor to determine if he can make the bore with regular slip joint pipe? Some good contractors can probably bore slip joint pipe without damaging it, however there are others we've had through the public bid process that are not as capable. This is subjective but curious what others do to see if we're going in the right direction.

 

[1503-44]

"others we've had through the public bid process that are not as capable."

Seems like the lesson has been already learned. HDDs are not the place you want to invite problems. When the choice is not clear, I tend to specify things that are best technical choice. If the contractor wants to do something else, well then I tell him that it'll all be on him and, if it works, we both get credit, but if it don't, he'll get all the repercussions. If he's still adamant to do it his way, think about it, but let him know that he owns it.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[bimr]

Restrained joints like the Certa-Lok are used forC-900 pipe HDD.

 

[LittleInch]

Depends on how the HDD is undertaken. In most case I know the pipe is pulled into the hole by the drill rig with a reamer on the front end.

Not many push it in and even then it is normally a mixture of push and pull from the front end.

So unless you're actually talking short distance where in fact you're auguring in front of it and pushing continuously, then I would restrain it.

Or use PE pipe and fuse it for the HDD sections?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jgailla]

Why are you not using fused HDPE for the HDD portion?

 

[TJH2161]

@jgailla,
We have trouble with service saddles leaking on HDPE pipe.

 

[1503-44]

No saddles in the HDD.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[coloeng]

You should definitely use restrained joint pipe for the HDD. Another option besides restrained bells in each joint is fusible C900. It's probably not a big deal in Louisiana, but in areas where you might be drilling through cobbly soil, the collars/bells on jointed pipe can increase the resistance or actually get jammed in the hole. I've speced fusible C900 in a couple of long bores under asphalt roads where this was an issue. The projects were both very successful. The cost is higher than Certa-Loc or similar restrained joint pipe.

 

[swazimatt]

I have never used fusable C900 (PVC for the rest of the world) but there is so much more meat to fuse on a PE pipe I would go with that. Are the issues you have with saddles, mechanical saddles or electrofusion saddles?

To your original question I agree with 1503-44, with one caveat, is there a higher risk of failure long term from a socketed connection vs a butt-weld or mechanically restrained pipe? you will not be 100% sure of what deflections are imposed on the sockets from the drilling and while they may pass initial pressure tests is there a chance that they may give way prematurely?

 

[TJH2161]

@coloeng - For whatever reason fusible PVC is the red headed step child of the pipe laying world here. I think there was a bogus article years ago about fusible splitting for 100's of feet somewheres in Florida and my General Manager has never wanted to use it. And you are correct, we deal with soft-medium clay in this area so we don't have those issues here.

@swazimatt - The saddles we had issues with were mechanical. I don't believe we have ever tried electrofusion saddles. I would agree that fused pipe in general induce lower stresses on the pipe than a socketed connection. I would be open to fusible PVC as opposed to Certa-Lok, but none of the other local utilities use it either so I've never pushed the issue to give it a try.