Restraining a connection between AC and PVC 2

[Shawner]

There is a sewer line being run through our system that directly conflicts with an existing 8" AC line. The solution was to keep the sewer line on it's current course and move the water line up and over where the sewer is going to go, leaving a separation of 0.5 meters. I started to type out an explanation but thought I'd just make a rudimentary sketch on Paint instead (attached).

Question is, how would you suggest we restrain the connections? The engineer decided on pouring a cubic meter of concrete on top of the transition couplings and tying back the elbows to restraint clamps (about 4" away). After seeing a bunch of fractures in AC pipe, I'm concerned that the additional weight of the concrete on the pipe will just break it sooner rather than later.

Any opinions?

 

[rconner]

Could you replace the AC pipe section back far enough, with new restrained pipe and fittings beyond the actual crossing each side, to accommodate the new off-set bend thrust, without exerting any axial thrust on the old AC? While AC pipe is hard to disturb around in any fashion, maybe this way at least you wouldn't have to worry about "restraint" on the AC? Might also want to use water main strength pipe for the new sewer for at least some distance at the actual close crossing.

 

[Shawner]

Thanks for the reply

We had initially suggested that as well (if they went back far enough (6-8m), they might even have gotten away without any bends), but they decided on this route instead (2m out from bend to transition coupling).

I'm just trying to get a good idea of what to do to fix it properly when it breaks in the middle of the night a couple years down the road.

 

[coloeng]

Use either DI MJ 45 bends with restrained glands(i.e. megalug or equivalent) or use DI MJ sweeps with restrained glands. This will transfer all of the forces through the fittings and there is no need to provide any type of restraint at the AC/PVC connection.

Have done this numerous times with no problems.

 

[dicksewerrat]

I'd use CIPP to line the AC sewer line to mitigate any damage and lay the water main over the sewer by going back far enought to keep the bends 5 feet from the sewer.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com