Replacement of Asbestos Cement pipe - options/risks 2

[LWCWayne]

Like most water utilities, we have some asbestos cement (AC) pipe in our distribution system, mostly in the 4"-10" range. We are looking to replace some in the near future and are looking at construction methods, risks, and responsibilites. We are lookinig at possibly totally abandoning the old ac main and replacing with new pipe. We are also looking at main bursting with a larger diameter pipe which will leave fragments of the ac pipe in place. The last alternate and most expensive is total removal and proper discarding of the ac pipe. There are risks associated with each alternate, as well as different costs. Does anyone have any information that you can provide regarding recommened replacement methods or responsible construction methods, etc.? Any information will be greatly appreciated.

 

[waterworker]

http://www.deq.state.or.us/aq/asbestos/ASBPIPE.pdf

http://www.ci.mesa.az.us/engineering/pdf/PS3_Removal_and_Disposal_of_ACP.pdf

You probably know all of this , but if you cut the AC pipe more health and safety rules kick in than if you pull it apart at each joint with a backhoe and a chain or sling.

Theoretically, once it's friable ( cut/broken ) you can't abandon it underground, and transporting/disposal is more technically and legally problematic if it's cut/broken than if it's not cut .

You can run a cable inside the pipe from one excavation to another ( fifty feet apart)in the right (loose or wet) soil conditions and pull it out in whole , unbroken pieces and simultaneously pull in new PVC behind with a trackhoe.

If you have enough depth of bury, you can dig a ditch to one foot or so above the old AC main, lay a new main on top , and extend every service line a couple feet from the ditch banks and saddle them onto the new main, abandoning the old one without touching it.

 

[HB2U]

We abandon it in place where we can. Usually constructing the new main adjacent to the old one and then tying over the service lines once the new main is pressure tested and activated.

As was stated earlier, it;s not a problem until it becomes friable, so by abandonming it in place, you avoid that issue.

In fact, there's no real reason to replace the AC pipe if it's performing ok.

Good Luck.