Sewer Pipes Abandonment 1

[angusa]

Toronto and other old cities in Canada are starting to feel the need of standardizing the way sanitary and storm sewers are abandonded. So far there has not been a standard requirement nor have the specs on a particular project been enforced and complied with. With redevelopment and recent brownfield legislation the sloppy abandonment that has taken place in the past has surfaced and has become an issue.
I wondered if you have standard specification or practices in your municipality that addresses this issue.
I would appreciate any feedback.

 

[RWF7437]

Best way I know is to fill the remaining parts of abandoned pipelines, manholes, cleanouts, etc. with a lean concrete mix. This will prevent collapse and, if they are later dug up accidentally, it will be obvious that these lines are not functional.

Good luck

 

[Focht3]

I'd suggest a flowable fill with a very high slump - it does a better job of filling all the voids.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[waseem19]

We abandon pipe and manholes by first flushing them with water , pipes filled with cement mortar and manholes are demolished up to 2-3m below ground surface. The rest of the manhole is filled with it's own debris and filled with sand to surface. Off course you have to include for the disassemble and collection and transporting to store of all the material that can be re-used, Manhole covers, ladders etc. do not think about digging your pipes out it will cost you more.

It used to be flushed only and then stoppers are used. but causes other problems such as collapse

 

[angusa]

Thanks waseem19,
It seems to me you (or your jurisdiction) have had dealt with the issue extensively. I would be interested to read a standard spec or a contract document excerpt pertained to this practice. Particularly, if there is some QC stipulation. The problem in Southern Ontario seems to be that the Contractors are not doing diligent job.
Thanks.

 

[KRSServices]

Angusa, you raise an interesting point regarding the abandonment of sanitary and storm sewer pipe.

Filling with flowable fill is a great idea, but costly as well. Plugging with concrete in the manholes and removal of the frames and covers are cheaper but come with issues as well. Since the municipalities I managed did not have abundant capital funding, in most instances, efforts were made to update the record drawings and cadastral plans showing abandonment of the utility. In many cases, these pipes were too small for any use or too fragile but were of sufficiant depth that collapse realy did not impact or disturb the exisiting road surface.

Cost was always an important consideration, and in many cases was the deciding factor as to the methodology of abandonment. In some cases, some pit run or soil, a half yard of concrete and a pavement patch was the extent of the physical abandonment, and the records/cadastral/GIS were updated.

KRS Services

http://www.krs-services.com

 

[Focht3]

I'm not sure what constitutes 'too costly' - a contractor called GeoFill is doing it for about $50/CY (on larger jobs.) It's a lot cheaper than digging them up, more effective than plugging, and more responsible in the long run. GeoFill recently did some work in downton Houston on an old sewer line near Reliant Stadium. It was fast (one night) and pretty cheap, overall.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[dicksewerrat]

On QC, you could require that the fill material be pumped into the line. Only allow 10 feet of pump hose into the upstream end of the line. Block the downstream end with block and mortar. Have a 2 inch tube installed into the line past the plug at top of pipe. When fill material exits the tube, plug it and have contractor hold what ever pressure was required to get material to downstream end for 10 minutes. the pipe should be full now. INSPECT, INSPECT, PUT YOUR NOSE RIGHT IN THE JOB.