Abandoning Steam Lines

7 feet by 6 feet??

Abandonment is a specific issue which depends heavily on the specifics.

Filling with flowable fill is a ggod way as is foamed concrete or PU foam.

Yes you normally need bulkheads to stop it flowing out.... Big diamters can have a lot of force so you need to design appropriatly. Bricks may not withstand the pressure, especially if newly constructed.

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Thanks @LittleInch. Yes the existing steamlines are quite large. I assume designing the bulkheads properly means taking into account the force of the flowable fill during construction.

How long?

your current data says it is a 7 foot diam pipe 6 feet long??

But yes - You can also do the fill in layers.

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Also: If you get a response it's polite to respond to it.

if you place the flowable fill in lifts, it will exert very little pressure. but what you are describing sounds more like a tunnel than a pipe.


i have tried specifying cellular foamed concrete before and got push back from the contractor. this is a specialty which most general contractors cannot do and dont want to sub out. likely to be expensive.

stick with very flowable fill. provide air vents as needed to fully fill the tunnel. expect that if it is not a uniform slope, you may end up with some voids that you cannot easily fill or determine if they are filled.

The steam tunnel is a 7'x6' rectangle section. The run is about 80'. Yes, it not a pipe - it's a tunnel.

It sounds like flowable fill is the way to go. Will the vents be similar to those used in rainwater harvesting tanks - i.e. goosnecks?

dont have to be goose necks, just need to bleed off air from the highest points in the tunnel. once the air stops and concrete / grout comes out, you have some assurance that the tunnel is filled. you may also need several grout injection pipes so that you can distribute the fill more evenly from one end to the other and from bottom to top

A steam tunnel is different from a steam line. A steam tunnel contains several steam pipes that are, in turn, routed to buildings for heat. It seems that they're common at large universities. They like to have a central power plant and use it to heat the campus.
As far as filling them, make sure that they never want to get in them again. All the methods above are not reversible, just in case they want to do mushroom farming in the tunnels in 2080.

Maybe I'm missing something here but... why do you need to place 130 yards of flow fill to abandon a steam tunnel? Disconnect, block it off, and be done...