Flowable fill to abandon a buried waterline
Flowable fill to abandon a buried waterline
(OP)
Hey all,
For larger diameter buried waterlines that we need to remove from service (16" diameter and larger), we specify that a flowable fill should be used to fill the pipe.
For this particular application, the soil bearing capacity is very low (N60 blowcounts of less than 8). The project manager is concerned that our waterline, once full of the flowable fill, will sink in the loose soil.
I've suggested we use aerated concrete, which can be mixed at much lower densities than flowable fill.
Has anyone ever used aerated concrete to fill a pipe for abandonment? Anything I should consider in my analysis that is unusual? Any other materials beside concrete that have been used with success?
Thanks!
For larger diameter buried waterlines that we need to remove from service (16" diameter and larger), we specify that a flowable fill should be used to fill the pipe.
For this particular application, the soil bearing capacity is very low (N60 blowcounts of less than 8). The project manager is concerned that our waterline, once full of the flowable fill, will sink in the loose soil.
I've suggested we use aerated concrete, which can be mixed at much lower densities than flowable fill.
Has anyone ever used aerated concrete to fill a pipe for abandonment? Anything I should consider in my analysis that is unusual? Any other materials beside concrete that have been used with success?
Thanks!





RE: Flowable fill to abandon a buried waterline
RE: Flowable fill to abandon a buried waterline
RE: Flowable fill to abandon a buried waterline
RE: Flowable fill to abandon a buried waterline
cvg - my thoughts exactly. But before I analyze the use of a cellular grout (or other lightweight fill), I wanted to know if the PMs concern was even a valid one.
RE: Flowable fill to abandon a buried waterline
RE: Flowable fill to abandon a buried waterline
Is the piping inside of a casing? Most railroads require casing.
You also should review your contract arrangement with the railroad. Some of the contracts have requirements on the method of removal. The last one that I reviewed did not allow abandonment, the piping had to be removed.
RE: Flowable fill to abandon a buried waterline
cvg - I spoke with the project manager briefly today and gave him a progress report regarding my analysis. I told him that one of the thoughts I've had was to introduce that aerated concrete into the pipe, mixed to about 70 lbs/ft3. This is easily achieved, according to the manufacturing data I have. But I don't know the cost delta between aerated concrete and our standard flowable fill. I'm also fighting the "But we've always done it this way" mentality in my office. I was hoping someone on here had done this before with success. As far as I know, we'd be the first in the area to suggest anything but flowable fill to abandon a buried pipeline.
RE: Flowable fill to abandon a buried waterline
If 90lbs extra per foot of pipe would cause it to sink, then the rail line itself would sink under the live load of the trains. If the trains don't sink ordinarily, then I wouldn't worry about it. My experience in this area is probably far inferior to many other posters in this thread/forum though.
Which then begs the question of what caused the blowouts. Was the pipe in good condition, or did it have leaks and whatnot?
If you're struggling with cost issues, is there a way to use flowable fill in most of the pipe, and aerated concrete under the rail lines? I've never been in the field to see how this is done, so I don't know how easy/hard it is. Might not save you any money by the time you're done figuring out how to do it.
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