drainage to septic tank..

[ekon]

This is an old house and not sure when drains were laid...not in the last 30 odd years we have been here anyway. Drain was not flowing but I rodded it through the top hole & on 7th 1 metre rod it cleared to the septic tank and the pipe flows fine now. The salt-glazed clay fitting on the outlet side looks like this:

However, though the drain pipe has now been cleared and water from a hosepipe runs away freely the main outlet "trap" is still blocked.
The front wall of the inspection chamber was damaged (now rebuilt) and pea-gravel from the surrounding area has, over time, got into the chamber and drain and the blocked the U-bend "trap". There was still "fluid" in the semi-circular glazed drain as it was only able to get away through the top (rodding) hole. I have managed to get a rod into the U-bend and after much wiggling around the fluid in the bottom of the inspection chamber/drain, which was backed up, went off down through the U-bend ..but the solids/pea-gravel is still in there so it will not run freely.

The U-bend is quite a way down and hard to reached with a (gloved!) hand. I have a pressure washer but was worried about washing what's blocking the U-bend away & down the drain towards the septic tank. Anyone have any thoughts on that? they would be gratefully received.

By the way what is the proper name for this "fitting" and can you still buy new ones if ever the need should arise? I found the photo on an Indian website after looking through Google images for one like mine.

 

[Burnerman]

That is an 'interceptor' trap - originally created to prevent vermin getting into the drain. The rodding hole should have a salt glazed plug in it.
Is the outlet from your tank to the soak away giving bother? If you can post a pic or two that would help.
John

 

[ekon]

Thanks very much John..interesting. Having had a quick look on the net I see why the plug is needed in the rodding hole! I will try to source a suitable "plug"..as far I can remember it has never had one.

Re your question about the outlet from tank to the soak away..no, not as far as I am aware...but can I ask what prompted you to ask that..do you think from what I have said I might have an issue with that too?

How would you clear the trap? .. I don't think my drain rods are flexible enough to do that job & like I said I'm reluctant to blast it with a pressure washer in case the debris causes problems down the line

 

[Ian H]

Get a bigger glove or a gully scoop. Maybe even a wet vac with 1 1/2 waste pipe taped onto it.

How deep is the manhole that it's in?

 

[Burnerman]

As above, but I'd consider hiring a wet vac to deal with the nasties, and do the lot at one go
With my elderly two chamber brick tank, I take great care that no solids should enter the soak away if at all possible - because you can't rod that one!
John

 

[ekon]

thanks again John.. and Ian. My fault really for not inspecting/repairing the front wall of the inspection chamber when a large digger went over it a few years ago!..I paid the price today..but all good now. Thank God for Toolstation rubber gauntlets.. though I'd have like the ones vets use for A.I. which can go up to the shoulder! Lying down I could just get my arm to the bottom of the U-bend and fished up quite a lot of assorted pea-gravel/stones over about 15 minutes of probing...it was blocked solid.
Not a job I want to do again for a while.
Thanks for your help guys..appreciated.

 

[Hugh Jaleak]

Wet vac, or ask the tanker driver to suck out the interceptor when you get the tank emptied. I do not advise you attempt to enter the chamber, even to refit a plug in the rodding eye, without at the very least gas testing it first. Hydrogen Sulphide could be present, this is heavier than air, and can be fatal, even in small concentrations.

Salt glazed drainage hasn't been widely used for many years, interceptors were phased out in the late 40's I think, and any damaged or repeat offenders for blockages, are usually removed. If anyone does actually want a new one, they are still available. http://www.knowlesdrainage.co.uk/

Interceptors were originally a Victorian idea, to seal the house drains off from the main sewer, and prevent rats and foul air getting into the house drains. A low level air inlet vent was usually fitted to the last manhole before the road, where the interceptor was located, idea being, air passing over the top of the stack would put a slight negative pressure in the house drainage system, thus drawing air in at the low level vent, and ventilating the system. The low level vents soon stuck open, and interceptor rodding eye plugs became dislodged. Never was a successful idea!

 

[ekon]

thanks for that HJ. We think that the house, which is maybe a hundred and fifty years old, was "renovated" around WW2 time and the drains were put in then. We cut some big pines down which the tree surgeon reckoned were planted around 1945 too which were probably intended as a windbreak.
Yes I have a low level AI vent into the chamber about 2 foot off the ground..no mica baffle, or whatever they used in it, though. The rodding-eye plug I have never seen either. Cannot imagine they thought any self-respecting rat couldn't swim through the interceptor..maybe the rats of old were less adventurous!! I would still like to cap it off nonetheless...I can bodge it with a number of bits and pieces including a clay plant pot dish..but is there anything proprietary I can use?..or a converter /adaptor to a modern fitting? I reckon the original pot-lid would have been about 105mm diameter.
I see an array of stuff here: https://www.drainagesuperstore.co.uk/search?keywords=clay+interceptor
but not sure what to buy?

The stoppers on the website HJ suggested look the part but the smallest appears to be of 130mm diameter and that is bigger than my interceptor rodding "hole":
http://www.knowlesdrainage.co.uk/images/products/spec/KRS.pdf
Any thoughts anyone? ..much appreciated as ever ..on this great website resource.

 

[Hugh Jaleak]

Any particular reason you want to bung it off? Only asking as its not essential, and I would try to avoid going into the chamber unless vital, without checking for gases first.

Whilst stopping Rats was one intention for the interceptor, (or Buchan Trap as some prefer to call it), I think its original purpose may have had something to do with the Victorian obsession with 'Drain air', which they initially believed was the cause of the diseases that were rife at the time. Bazelgette and the other pioneers of sewers and sewage treatment, may have borne this in mind when designing the early systems.

 

[ekon]

it was just to make it harder for any vermin to get in that's all..but I am not connected to mains sewerage just a septic tank..and as I said before I think any self-respecting rat would be able to swim through the liitle bit of "water" in the U-bend of the "trap". So I may just leave it.

 

[Hugh Jaleak]

I would have thought it unlikely any vermin would be in the run between there and the tank, in fairness. They prefer bigger sewers usually, where there are dry area on benching etc to nest, usually they come up the house sewers to find an exit to search for food.

Any sign of vermin activity, some poison in appropriate places usually helps.