Problems with "ultra-rib" PVC pipe? 1

[MMMrob]

I'm specifying sanitary sewers (between 200mm and 375mm) for a residential subdivision and have heard that some Ontario municipalities prohibit the use of ribbed ("ultra-rib") PVC pipe. Can anyone direct me to some literature (articles, standards, etc.) that sheds some light on why the use of ribbed pipe is more and more often being frowned upon? Thanks.

 

[waterguy]

Good question.

I don't have any particular references or standards to pass along, but in London (Ontario), we have regulary used ribbed PVC for storm sewers. As to why some municipalities may not approve of ribbed PVC for sanitary sewers....


1. To differentiate the services. If for example both the storm and sanitary services are ribbed PVC, the municaplity might be concerned with confusion over which service is which, connecting private drain connections to the wrong sewer, etc..

2. Problems (leakage) at the pipe/manhole connection.

3. My guess is that the biggest reason some places don't like ribbed PVC is simply because they haven't used it in the past, and don't see a need to change their standards. I know of one municipality that would still require the installation of small diameter ductile iron watermain if it wasn't for local developers and consultants insisting that PVC was acceptable.

 

[darth051]

I may be able to shed some light on it...

Down here in the Windsor area, it appears that the problem stems not from the pipe itself but rather a couple contractor's who installed it. Basically, it was installed in a similar manner to concrete pipe which requires only minimal compaction of the bedding and cover material to maintain its integrity. However, since PVC pipe, and Ribbed Pipe especially, requires proper compaction of the bedding and cover to provide pipe strength, the pipe failed. Now, this happened long ago and only a couple times, but it was enough to taint ribbed pipe in the minds of several of the local town engineers. Then the town engineers all get together and share horror stories... well, the "taint" just keeps spreading.

Just as a side note, I was able to use ribbed pipe in one of the "tainted" jurisdictions by enforcing the requirement for compaction testing of the bedding and cover material prior to backfilling. As this type of testing wasn't standard practice down here it raised the install price, but it still worked out cheaper in the end.

David Dietrich
KMK Consultants Ltd
Windsor, Ontario, Canada

 

[MMMrob]

Thanks for your responses. Since posting this question, I received word from the municipality that they don't permit ribbed pipe. So unfortunately it's a moot point for my application. But there may be an opportunity for me to ask them why...

 

[hydrae]

I just ran across an installation of ribbed pipe on a private storm system, it broke very easy, the material is brittle, hence it needs to be fixed, getting the materials to fix it has been a chalenge, can not just use a fernco coupling, need the adapters and gaskets to convert to a 3034 pvc then splice with a fernco.

I can see why it is not in common use.

Hydrae

 

[semo]

Hydrae probably has the main reason it is not allowed.

Our area in the US does not use the material either. Experience from the past showed that the material broke down easily, especially with UV exposure. Regular PVC manufacturers have solved most of this problem; but, all ribbed pipe I've seen has chipped and deteriorated over short time periods.