Negative plumbing drain slope in radiant floor slab-on-grade building

[caluna]

Hi, we have a building (one storey slab on grade, radiant tube infloor-heating,with themosyphons under bldg to keep permafrost frozen ( 68 N latitude). The furthest part of drain line (from exit of building drain line from the building) has shifted. (Plumbing drain lines are run in insulated chase below the slab.) Half the line now slopes uphill, and evidently does not drain well! To add to the problem-this is a secure facility for young offenders and the worst (most sunken) part of the drain line is at the Isolation and Segregation cells. Thre are several branch lines coming into the drain line and some of them are slanted upward too. Right now staff are rodding and flushing the main line out daily.
Because of the security and due to heating and thermosyphon piping in floor, it will be tough to jackhammer up floor to put in sump or run new drain. Not enough height to raise individual fixtures. It would be hard enough to have a space to put a sump and grinder pump and pump back to line.. Vacuum system won't work as we don't want to suck fixtures dry in nearby areas.. Any thoughts please?
Heather

 

[dik]

a little confused. Is the heating tube system pressurized and if so, does an upward slope cause any problems?

Dik

 

[caluna]

The slight upwards slope does not trouble the infloor heating heating system too much, as it is a pumped system... However the thermosyphon piping relies on flow of gas/liquid merely on temperature difference so that up-and- downs in the loops act like traps and prevent the cooling effect from happening so well.

The radiant heating tubing is embedded in the concrete slab. We are not sure yet if the slab itself has shifted,(I suspect so) or if it just the plumbing lines, which are suspended underneath the slab in an insulated chase.... To get to plumbing lines you would have to jackhmamer up the slab, while avoiding the heating tubing (we can use thermal scanning to find heating lines). Of course there are cleanouts up to floor as required. However, inches UNDER the slab and the plumbing chase are thermosyphons which are refigerant-filled tubes transferring heat from ground to keep it frozen. These you do not want to puncture-if the permafrost melts the building will heave and move more..Which kinda rules out the possibility of putting a new sump pit in the ground and pumping sewage from it..

 

[MintJulep]

How much space below the slab? Is it dirt, or a second slab?

 

[caluna]

The slab is on grade, on a layer of gravel fill more than a foot deep. In the fill are the thermosyphons which run (several inches below slab) in large loops aross the building.The plumbing pipes run in an insulated chase about 6 in square suspended below the slab (in the fill). Where thermosyphons meet the plumbing chases(s) the cthermosyphons are bent down along and back up to accomodate the chase(s)