AC Pipe Abandonment in place 2

[yogibear1]

We have an old AC water main (about 3000 LF) that we want to abandon in place with grout fill or flowable fill. We are aware of the friable nature and environmental hazards of AC pipe hence we don't want to to remove it. The grout fill is meant to mitigate against any future subsidance of the soils over the out of service pipe. We can locate the ends of the pipe and middle, and there are no service branches. I am looking for tips on technique (such as high point venting), recommendations on the composition of the grout/slurry mix, etc.

 

[RWF7437]

You could use PCC grout or even, sand mixed with water and ordinary dishwater detergent. The detergent helps make it "flowable". Experiment a little with small quantities to find the right mix.

 

[treg]

Check with an oil well service company such as Haliburton. They have done things like this before.

 

[dicksewerrat]

Most DOT's have aspec for the use of and mix designs for 'Flowable fill' or low density fill. You can pump this stuff to almost any pressure you want. Talk to local concrete pumping contractors.

 

[sc]

Funny how utilities can leave AC where it is but the home owner can't, something about future owners digging it up accidently and having a remote cahance of health problems.

sc

 

[Zambo]

Dishwater detergent sounds primitive, but does have the same effect on concerete as a plasticiser so could work.

You will need high end venting. Before grouting try blowing out with compressed air to try to rmove water lying in the pipe. Any remaining water will be flushed out as you pump grout in. Check the flowability of the grout as it exits the vent, ideally the flowability of the grout will be the same as it exits as when it enters the pipe.

Why not phone up your local concrete supplier and check they have a concrete pump, this should provide enough pressure for your purposes. Grout is often used to lubricate pumps and lines before pumping through structural concrete. It is quite possible that the same grade of grout will suit your purposes.

Zambo

 

[KRSServices]

What size is the pipe or why is abandonment with a grout fill being specified? Unless the local authority is specifically prescribing grout filling it seems to me that the filling process may be an expensive undertaking.

I have abandoned miles of AC, rotting ductile and cast iron pipes over my career and have never had the need to fill with a grouting (or similar) material. Just my two cents worth, keeping in mind that I do not know all the circimstances surrounding the project.

KRS Services

http://www.krs-services.com

 

[yogibear1]

The pipe size is 14 inch and is always under pressure (though it is low). It was installed years ago (1970's) by a Developer. The pipe runs partly on private property, and partly w/in road ROW. Subsequently a condominium complex was built over the pipe (without a utility easement). The County aquired the work when the developer went under.We plan to serve the reclaimed water from another loop (high pressure) and the AC line will go out of service. The grout fill is really to protect or mitigate against collapse of an empty pipe and what potential damage could happen on the condo complex. So this is mostly insurance, making up for sins of the past.

 

[stanier]

You could perhaps look at using a fly ash paste and designing a pumping rate so that laminar flow occurs. You will find most fly ashes will solidify in twenty four hours.

Fly ash from your local power station should only cost you a trucking fee as it is a waste product. I have pumped up to 75% solids by wieght 11km.

You could use a mobile concrete pump, Schwing, Putzmeister or other to do it. Fly ash could be slurried in cement trucks and loaded into a portable conrcrete pump. Slurry could then be pumped until your line is full. If you are concerned about voids put a poly pig in front of your slurry to drive out the air with the liquid column.

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