Moving A Manhole

[LinusIT]

Hi

I need to move a manhole because it’s in the way of a porch extension. I have two manholes in my front garden, one is for my house and the other is shared between neighbouring properties. The manhole in question is the one for my house. This manhole has 3 entries and one outlet, the outlet being a dropshaft to the shared manhole further forward in the garden. I plan to use an inspection chamber elsewhere to replace the current manhole. My question is, how do I connect to the existing drop shaft or do I need to be going down a different route?

I have included a rough picture showing the current situation.

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• LinusIT
• 17 Mar 2010
• 1

I hope someone can advise me on what to do.

Thanks

 

[Nige F]

Sorry, but the drop shaft on the exit of a manhole dosen`t make sense to me A backdrop coming into a manhole would And you`ll need Building Control involved - John D Trench - will tell you soon

 

[noseall]

Perhaps he means an interceptor.

I am not a fan of interceptors as i think they are more trouble than they are worth.

 

[Nige F]

Indeed, and as to moving one Unless BC says it can be left out It`s a shame because it`ll make a porch an expensive job

 

[LinusIT]

Maybe my terminology is incorrect, ooops. I have done another (rough) drawing of the side view and also taken some real pictures. I hope this clarifies my situation better

Rough Side View

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• LinusIT
• 17 Mar 2010
• 1

First Manhole

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• LinusIT
• 17 Mar 2010
• 1

 

[noseall]

If it were me i may consider moving the inspection chamber to the left as opposed further away from the building and re-hash the stack pipe thus modernising it too.

The stack pipe could be moved over too provided there are no windows and just extend the loo pipe to suit. This would be more convenient regards the porch.

You may be in a position then to boss the sink waste directly into the stack.

I bet the stack pipe is an old iron or asbestos fella?

 

[LinusIT]

I have replaced the stack pipe from the ground up already. I will be replacing the remainder during this job. I'm pretty certain whatever is left of the stack pipe is the asbestos stuff.

I can't move the stack pipe as there is nowhere for it to go, plus it would mean doing the upstairs bathroom plumbing all over again.

 

[Nige F]

Thanks for the pic. Strangely it looks different to an interceptor that plug you removed is nearly horizontal -does the pipe under it drop down. not seen one like it here in sussex

 

[LinusIT]

Pictures do a better job than my drawings, haha. It definately isn't an interceptor.

The first Manhole is about 2ft (at most) underground and then second one is about 5.5ft-6ft underground.

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• LinusIT
• 17 Mar 2010
• 1

 

[Nige F]

Well, you`re both in Staffs, and Noseall maybe hasn`t seen one like that- Anyways have a look @ a Marscar Bowl using google - That may be the answer to connecting to the drop pipe

 

[Static]

My house drainage has a similar manhole (and yes im in sussex) its on a combined drainage run for a 1930s bungalow. It is the last manhole on my property before the main estate sewer
The plugged pipe is a rodding point that rods beyond the U trap to stop the whole estates drainage smell coming up my spur.

Well my system may be different but the chances are your pipe doesnt go straight down (as it would block up alot) but goes at a fairly steep angle and the plugged pipe is a rodding point.

As you intend to move the manhole anyways it may pay to dig around in front of the manhole to confirm this

 

[LinusIT]

Thanks for the suggestion Nige F, I'll have a look and see if I can use one of these. The only problem that springs to mind is placing that on top of the vertical outlet would make the inlets quite high, maybe I'd have to lower to manhole first hand before using a Mascar Bowl.

Static, the plug at the top is just for rodding purposes, because the waste flows down before the plug end. The drop is vertical, most definitely. I was in both manholes yesterday clearing out waste that had dropped down whilst I've been excavating the area.

It does tend to get blocked quite easily but then again, it was blocked yesterday because of rocks & soil etc falling down.

 

[LinusIT]

I've had a look and I think the marscar bowl would do the trick nicely. I would have to lower the placement of the marscar bowl so that the pipes have enough downfall.

Anybody have any tricks/tips on how to temporarily block the downward pipe so I can remove the old brick manhole from around it? without having all the rubble etc falling down.

Also once I've removed the old brick manhole, how is it best to cut the downward pipe?

 

[Hugh Jaleak]

I would strongly recommend you obtain a 110mm stopper to plug the pipe. Tie a rope securely to it so you dont lose it, but this should stop anything falling down the pipe. Half a brick getting wedged will not be useful......

To cut the old salt glazed pipe you need an angle grinder (or disc cutter), but gently does it is my advice. Chamfer the cut end, then a Fernco or similar coupling will take you to 110mm plastic. Alternatively if you can get to a joint on the old pipe, it may just pull free, then an Osma part no. 4D107 or equivalent cemented into the socket should do the job.