Adding a tee to underground 4" SDR35 PVC pipe

[Kirkpatrick]

I need to connect a tee to a pipe buried 21" down, well above the frost line. This pipe carries water collected from the hill behind my house to just above a storm drain in the street in front of my house - it doesn't have anything to do with my house plumbing or anything else, just delivers the water collected by a buried perforated pipe. The hill is so water-laden that new trouble areas keep emerging s0 I dug a trench system that is working very well but I need to connect it to the pipe going to the storm drain. I would like to use a saddle tee with flexible fittings but can only find ones that are designed to connect to schedule 40 pipe. I've read about workarounds like using a gasket to get the tee to fit my pipe but they are not specific enough for me to feel confident about doing it. I really want to avoid cutting the pipe and using a standard tee if I can. Any thoughts or specific guidance would be much appreciated.

 

[wwhitney]

I really want to avoid cutting the pipe and using a standard tee if I can.

Why is that? I think that's what you're going to have to do, because saddle tees for SDR35 pipe seem to only be available for 6" and larger pipes.

Cutting in a tee just requires using two rubber couplings. Once you have the run of your tee assembly, cut out maybe 3/8" more of the pipe than the tee run length. Then you can put the rubber couplings on the (cleaned) cut pipe ends, slide the metal shields away from the cut, and roll the rubbers back onto themselves. The available space should be just enough for you to push the tee in between the rubber couplings, then you can unroll the couplings, slide the shields into place and tighten the couplings.

Getting the right coupling is a bit tricky, I'm not aware of a 4" SDR35 to 4" SDR35 coupling. You could just use a standard 4" Schedule 40 (4.5" OD) to 4" CI (4.4" OD) coupling, and tighten down on the bands for your 4" SDR35 (4.2" OD). Or you could use a 4" no-hub coupling, I think that would be a bit better.

The coupling makers do make have couplings for "thin wall plastic" but only to transition to 4" Schedule 40, e.g. Fernco 3009-44. And if I recall the OD of an SD35 hub is about 4.5", the OD of 4" Schedule 40. So if you can get a smooth SDR35 hub (e.g. no embossed lettering), either from the tee itself, or a coupling, or the bell end of a bell-end pipe, you could use a Fernco 3009-44 to connect that to the SDR-35 pipe without having to try to tighten the coupling alot. I would fill the hub with a small piece of pipe solvent-welded into it just to keep the ID consistent.

Or you can use a standard Schedule 40 to Schedule 40 coupling (e.g. Fernco 3005-44) and just use the hub trick on both sides.

Cheers, Wayne

 

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[Kirkpatrick]

Why is that? I think that's what you're going to have to do, because saddle tees for SDR35 pipe seem to only be available for 6" and larger pipes.


Thanks for your detailed reply! I wanted to avoid cutting the pipe because it is carries a lot of water all the time, so I would have to excavate more to ensure that I can do the connection before the water covers it all up. The running water would also interfere with use of solvent and/or cement. I think I will buy an extra piece of pipe and several types of fittings so I can do 'test runs' in my garage. What method of cutting the pipe would you recommend for speed without losing too control? I was going to cut half-way through in both places so the water wouldn't start flooding until I was close to being done.

 

[wwhitney]

OK, updated suggestion:

Get (2) Fernco 3009-44 or Mission TWP-44. Make up the tee assembly you want to install with a several inches of pipe into both of the run sockets and ends that are 4.5" OD. [This could be using a Schedule 40 tee and Schedule 40 pipe, in which case on the branch you'd need to convert back to SDR35, perhaps with another rubber coupling; or all SDR35 parts, with an SDR35 hub at the ends of the run segments.] Preinstall the couplings on the ends of the run, with the shielded coupling pulled back on the to the run segments and the rubber folded over.

Excavate enough length (at least 6" more on each end) and excavate under the pipe 1 - 2". Clean the pipe, mark for your cuts (using tape around the pipe to get a guideline), clean the pipe just outside the cuts well (where the rubber couplings will attach). Get a reciprocating saw with a fresh 9" blade, fine toothed is maybe better than coarse toothed (not sure on that, either should work). Practice a few cuts on scrap pipe, duplicating the position you'll have to cut it from in the trench.

Then you just cut the pipe squarely at each mark, in a single motion from above. [The trick is ensuring the stroke neither hits the soil, nor rises up past the inside bottom of the pipe. So maybe excavate a little extra under the cut locations.] Use a razor blade to debur the outside edge of the pipe (I usually do the ends and the inside corner, but with water flowing I might skip it). Pop in your assembly, unfold the rubber couplings, move and tighten the shields.

If your tee (wye or combo, really) is going to be flat (well, 2%), and there's really a lot of water flowing, I could see the water backing up into the branch and making it hard to make a solvent weld connection. So if that would be a problem, and you can afford the height, I'd suggest rolling up your tee 22.5 degrees and then using a street 22.5 degree elbow to go flat.

Cheers, Wayne

 

[Reach4]

I need to connect a tee to a pipe buried 21" down, well above the frost line. This pipe carries water collected from the hill behind my house to just above a storm drain in the street in front of my house - it doesn't have anything to do with my house plumbing or anything else, just delivers the water collected by a buried perforated pipe.

Does the flow stop after a cold January/February?

How about blocking the outlet with a Cherne test ball so that flow stops. Then freeze above the work site with dry ice. Release the ball, and let the pipe drain. Do the work while the flow is stopped.

Danger of the pipe freezing cracking the pipe? I don't know.

 

[Fitter30]

Two pvc repair couplings a tee and some pipe