Minimum depth for a mini access chamber?

5 Jan 2016
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United Kingdom
Hi all

I have a svp stack at the front of my house, and at the rear i have a new 450mm access chamber, passed off by bco.

Id like to replace the clay from the svp up to the 450mm inspection chamber at the rear of the house. However while doing this i would like to put a stub stack in the middle of this run for my downstairs w/c.

Id have to use a 45 deg rest bend. As i understand from previous post, i need a mini access chamber as its a change in direction.

Is there a minimum invert depth for a mini chamber? The drainage isnt very deep and its a shared access driveway so a vehicle will go over it.

Its the last remaining clay in the ground for our house and its leaking at the svp rest bend. I have done all my other drainage myself but still have couple loose ends to tie up...

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Just to add onto this, my main concern is shallow depths, maybe i dont need a chamber at all and a simple stack that has a rodding point in it? The stack would go into a rest bend, straight into a 45 deg branch. Access is possible from the 450mm chamber that is 3 meters away.

To my limited knoledge, the whole point of the mini chambers is access to rod? I could see the need for one if it wasnt accessible from the base or top of a stub stack. Maybe i have answered my own question!
I wouldn’t put a chamber too close to a stack, you risk turds jumping up the benching.

I would just use a Y junction but not a 45degree rest bend.

Hi ian.

I get you, i would cover my self by having a rodding point on the stack, and the 450mm chamber is not too far down the line anyway to rod from the other side.

I think that covers me? The chamber would of been needed if there was no other access, have i got that right?
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I’d say so. The junction would be unlikely to block but if you have access up and down there would be nothing to worry about.
I had a customer who had a house that was extended to the max, he had an internal soil stack that was completely blocked with no external manhole and he wanted me to cut into the soil stack and jet from there. I walked away from the job as I explained to him that sewage would spill all over his floor. His reply was 'that's ok, you will be clearing it up', he said it with a straight face, I thought he was joking but he wasn't.

It is absolutely unbelievable what some customers expect. I went to empty a Septic Tank once for a rather large property. Guy was a Businessman, on the Council and thought he was something special. After emptying his tank he instructed me I was to go down it, (he seemed rather put out I hadn't got my own ladder!), and inspect the outlet as it wasn't draining very well. (Hence him having to pay the grand sum of £95 at the time to have it emptied.)

He was even more put out when I told him the charge covering the tank emptying, under no circumstances would I be going into his tank, (nor would anyone else from the company), and he would have to get it inspected by a third party at his own expense!

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