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Anonymous Poster

Pouring Concrete Above Sewage Pipe Line

02/19/2010 11:54 AM

during visiting working area in infrastructure project (sewage pipes installation ) i saw that they are pouring concrete above pipe line in some areas .

what is the purpose of this concrete ?( i think it for life load)

what is the reference for it (BS , ASTM, AWWA)?

thanks

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#1

Re: pouring concrete above sewage pipe line

02/19/2010 12:01 PM

One possibility is to stop the sewage pipes from floating away if the installation floods.

Have "they" been asked why?

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#2

Re: pouring concrete above sewage pipe line

02/19/2010 12:14 PM

Too vague for reply.

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#3

Re: pouring concrete above sewage pipe line

02/19/2010 12:51 PM

It could be for elbow blocks, it could be a very lean mix of soil and cement such as K-Krete so it doesn't have to be compacted. There are certainly more reasons, such as PWSlack's, "to prevent flotation".

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#4

Re: Pouring Concrete Above Sewage Pipe Line

02/19/2010 11:07 PM

Concrete sewage lines...?

Your probably right especially if road surface over pipes...where for some reason, including expense, it is not feasible to bury pipe deep enough. Next time try to ask someone at the site.

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#5

Re: Pouring Concrete Above Sewage Pipe Line

02/20/2010 12:19 AM

I have seen underground high voltage oil-filled cable installed with large paving blocks placed over it to deter backhoe guys. If I owned a pipe or cable, I might want to armor it like that. Not much of a cost, and those backhoe guys can do a lot of damage when they just guess there is nothing in their way.

It costs more to cut up a high voltage cable, accidentally, than a sewage line, but that would be my guess.

Segmented water and waste lines tend to come apart as soil shifts. This might be an attempt to keep segments together.

David

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#8
In reply to #5

Re: Pouring Concrete Above Sewage Pipe Line

02/20/2010 8:10 AM

Since, as you say, it is in some areas - GA for dhgrant's answer#5.

It is done to protect from future backhoe work or trencher work.

Flowable fill is inexpensive and the operator can feel it as the bucket's teeth catch it.

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#6

Re: Pouring Concrete Above Sewage Pipe Line

02/20/2010 2:49 AM

could be that it is intended for areas where vehicles will circulate.

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#7

Re: Pouring Concrete Above Sewage Pipe Line

02/20/2010 7:10 AM

could be the pipe is under a main carriageway and shallow in which cocrete protection of the pipes is required.

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#9

Re: Pouring Concrete Above Sewage Pipe Line

02/20/2010 10:30 AM

Hello,

It is usual to install concrete anchor blocks along a sewer pipeline when there is the presence (or historical high seasonal level thereof as indicated in the soil mass) of a high groundwater table or the possibility thereof in order to prevent flotation (buoyancy) of the pipe before and after the trench has been backfilled. This buoyancy condition can occur along pipelines constructed of all types of materials, such as: RCP, DIP, CMP, HCMP, PVC, ABS....really, the weight of the pipe doesn't come into play too much because the forces causing buoyancy can far exceed the gravity forces due to the weight of the pipe.

I've seen in the past on several occasions where the concrete anchor blocks were not installed, even on Reinforced Concrete Pipe (RCP) and Ductile Iron Pipe (DIP), where the pipeline became buoyant and popped-up out of the ground! This is especially true when you have sanitary sewers with daily low flow conditions, or storm sewers that remain empty most of their lives or even conveying a small amount of groundwater infiltration. Also, concrete anchors are even installed on water mains if there is a groundwater problem because the design engineer has to factor in the possibility that the water main may become empty sometime in its design lifetime (usually 75 years) due to either leaks or maintenance purposes.

Additionally, if anchor blocks are installed along a pipeline or force main on steep terrain, it is done so as a measure to prevent the the movement and hence resulting separation of the pipeline at fittings and pipe joints.

Hope that helps!

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#10

Re: Pouring Concrete Above Sewage Pipe Line

02/22/2010 1:26 AM

While there have been many good thoughts put out by the previous posters and indeed the protection and weighting is sometimes the reason for an encasement the most often reason is to ensure that the sewer line does not leak to an adjacent water main. The standard is usually at least ten feet of separation between water and sewer mains or service lines. When this distance cannot be maintained then one or the other main must be encased in concrete.

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Anonymous Poster (3); CaptMoosie (1); dhgrant (1); Geode Hunter (1); omw7 (1); passingtongreen (1); PWSlack (1); Sourdough (1)

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