Blocked waste pipe - again

[Serval]

posted up on here back in October about the waste pipe on a flat Ive got rented out being blocked....

That branch goes into a vertical stack, shared by the flat above and below.
Back in october i had dyno rod take a look at it and they said the pipe was scaled up.
They cleaned out the pipe work including the section of vertical stack below the branch using a picote machine.

They sen some pics of what they removed:

All has been fine until this week when i get a message from the tennants saying the toilet is slow draining and getting increasingly worse.

Spoke to the ground floor occupants who haven't noticed any major issues with their toilets. Not managed to get hold of whoever is in the top floor yet to see if they have any issues. so it doesnt sound like theres a problem further down the line

Does the stuff in the last two pics look like scale and is it likely to build up again in such a short space of time to start restricting the pipe again? (london hard water)

Any ideas what could be the cause this time given its only about 5 months since getting the previous clean up job done and what my options are?

Thanks

 

[WC1]

Hi, as before, "descaling" a soil pipe is not a real thing. Thats cement or plaster (as was previously suggested as a cause, iirc)

 

[moonlight]

Sorry but it does look like scale. Here is a Youtube of a drain descale.
.
Looks like far to many toilet wipes. Not recommended to put down the toilet anyway, not bio-degradable.

 

[WC1]

+ 1 for wet wipes, - 1 for limescale.

 

[Chuck]

My understanding is that scale in drains is due to ingress of groundwater, which is high in CO2 and calcium. The CO2 outgases inside the drain causing precipitation of of calcium carbonate. It's a symptom of a leaking drain, which needs investigating.

That said, 5 months seem rather a short time for enough scale to block a drain to form in this manner.

 

[Serval]

Hi, as before, "descaling" a soil pipe is not a real thing. Thats cement or plaster (as was previously suggested as a cause, iirc)

Yea i thought so...
If scaling was actually a thing i was expecting them to remove something that looks more like actual limescale that you'd get in the bathroom/kitchen etc.(albeit much thicker)

When i got sent these pics I did think it looks more like some sort of building waste product but thought id double check here

 

[WC1]

My understanding is that scale in drains is due to ingress of groundwater, which is high in CO2 and calcium. The CO2 outgases inside the drain causing precipitation of of calcium carbonate. It's a symptom of a leaking drain, which needs investigating.

That said, 5 months seem rather a short time for enough scale to block a drain to form in this manner.

Thanks Chuck. Please would you post up a reference or two for that. I am dubious but I am always happy to be proved wrong, its one of the best ways to get closer to the truth.

 

[WC1]

Yea i thought so...
If scaling was actually a thing i was expecting them to remove something that looks more like actual limescale that you'd get in the bathroom/kitchen etc.(albeit much thicker)

When i got sent these pics I did think it looks more like some sort of building waste product but thought id double check here

Put an addendum on your ten.ag. not to put wet wipes (none are safely flushable), kitchen waste, cooking oil, sanity products etc down the drains toilet or sink. I'd say the vast majority of blockages (above ground, as you have) are human error, sometimes compounded by a little burr on the pipe or a slight lack of fall.

 

[Serval]

Assuming that this is a soft blockage, do you guys think it would be fairly easy to clear with a set of drain rods and one of those corkscrew type attachments via the rodding access hatch located on the corner elbow?
(not the nicest of jobs but should be fairly straightforward right?)

 

[WC1]

Define "easy" !
Have a go by all means, if you get cheap rods remember to Always turn clockwise, in and out. Best to get Bailey locking rods - no chance of losing anything in the pipe.
Pushing hard from the outlet end toward the bathroom is not advised!
As its a let property it is a business which requires investment to see a return, iiwy i would call a local independent drain engineer to clear and cctv , then you'll know if its a fault on the line or human error.

 

[Chuck]

Thanks Chuck. Please would you post up a reference or two for that. I am dubious but I am always happy to be proved wrong, its one of the best ways to get closer to the truth.

Here's a case study

http://scap1.org/Collection%20Reference%20Library/Report%20to%20Joe%20Parker%5B1%5D.pdf

that demonstrates a build-up of aragonite and calcite and suggests it formed in pretty much the way I described.

I think that your explanations, or possibly some chemistry involving fat, are far more likely than this type of scale formation but the mechanism I described is possible. It would be interesting to test a sample of the OP's scale shown in their img009.png to see what it really is.

 

[WC1]

Thanks chuck that is a very interesting paper and it does show the possibility of scale occurring, however the environmental conditions required are very specific and don't occur in London. But it clearly is possible under certain circumstances.

i think the chemistry involving fat is "saponification"

Fat turns into soap in sewers, contributes to overflows

Researchers have discovered how fat, oil and grease can create hardened deposits in sewer lines: it turns into soap! The hardened deposits, which can look like stalactites, contribute to sewer overflows.

www.sciencedaily.com