What is the best way to repair a 3" or 4" buried pipe? I am looking for the details of dealing with a break in the pipe, where the two ends are stationary. This should be the same as any underground tie-in. What is the best method?

With new plumbing, you put glue or screw one piece onto the existing piece and work out, but with a buried 3" or 4" pipe, the ends are fixed--I can't slip anything on to glue it or screw it on.
1. using two couplings and a length of pipe, as I have done with 3/4 inch lawn sprinkler PVC, seems impractical because I can't bend the 4" pipe. Can I cut the stop out of a standard coupling, slip it over one side, then center it?
2. telescopic or extender couplings, split pipe couplings, and similar, if available for large diameter pipe, seem like gimmicks or compromises
3. how about gasketed repair couplings? Or a union? Or rubber couplings that use hose clamps or a stainless clamp? I worry about the rubber deteriorating over time.

What is the best way to tie into the plumbing for a permanent underground repair? The pressure is not high--just a few PSI.

The break is on a 3" or 4" fire hydrant pipe that comes off my pool (9 ft deep), runs underground, then comes up with a 3" galvanized standpipe with a fire fitting. The pipe from the pool is PVC and the standpipe is galvanized steel set in a concrete block. I don't know exactly where the transition is as it is under water right now--the break is below the pool water level. The pipe is often often under water for months during the rainy season as the water table comes up quite high. It has been in place for 10 years--I don't know whether the galvanized pipe could have rusted that fast.

I isolated the leak (not sure if it is the only one!), about 4 ft underground and close to the standpipe. I need to block the pipe at the bottom of the pool or drain the pool level then pump the hole out to see the break and pipe clearly.

What do you recommend?


thanks

iamgrowler

Ordinarily I would suggest a 'Dressler Coupling', but I have never seen one available for three or four inch pipe.

Call around tomorrow during business hours to a few Plumbing Supply Houses to see if such an animal exists.

serendipity pools

I do this all the time with PVC. If it is a pressurized and buried system, then you simply can not take any chances with future leaks. Dig a section that will give you good access to at least 12" of pipe. The better you dig, the easier your repair will be and the greater the likelihood of fixing the leak permanently.

Cut a 12" section out of the pipe. You will need 4 - 90 degree elbow fittings and you are going to glue on two elbows aiming directly upwards (use a level) on the stationary ends of th pipe.

Now it is a simple matter of cutting a section of pipe that you will glue down into the two waiting elbows aiming upwards. Dry fit and test your pipe lengths before primer and gluing. When you make the final connection you will glue two fittings at one time. Be sure to use lots of glue.

Good luck

Steve Goodale
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