Common Sewer Submerged In Concrete

[Johnny Jekyll]

Our plan is to connect to a 100 year old common sewer on private land (our own land) for our self-build. The existing common sewer is 150mm salt glazed, in collar sections, submerged in concrete (see photo).

 

We have permission to connect via either a manhole or preformed 'Y' (oblique) junction, built to Sewer for Adoption 7th Edition standards. The choice is ours. We will be installing ourselves.

 

Preformed Y junction would prove a nightmare with all the concrete surrounding the salt glazed pipe, trying to shave it clean enough to accept the shear banded couplers on either end without cracking it.

 

As a result, manhole may be preferable, except am I dealing with the same problem?

 

To explain... Sewers for Adoption states that you should allow for any differential settlement between the manhole and pipeline, with short lengths of either spigot/socket butt pipes being built into the manhole wall.

 

So, considering the existing common sewer is submerged in concrete, would I still need to shave back and add rocker pipes or shear banded couplers (flexible joints) to the outside of the manhole to allow for the differential settlement?

 

I’ve spoken to two friends with knowledge / experience in sewer works and they said I shouldn't need the flexible joints because it's already submerged in concrete.

 

I thought I’d get your opinions too before I bring this to the attention of the water utility. What do you think?

 

Thanks in advance.

[Dave Jones]

break out the concrete, couple of clay to plastic collars, fit a Y and a new chamber. A mornings work tops.

[crooksey]

2 hours ago, Dave Jones said:

break out the concrete, couple of clay to plastic collars, fit a Y and a new chamber. A mornings work tops.

 

+1 

 

Depending how thick the concrete is and if this area will get any vehicle traffic (during construction so large vehicles). You may want to construct a brick chamber, two courses of engineering brick in water bond. I would only suggest this if the area is getting considerable traffic though, as probably be 3-5 days work with a temporary diversion for the pipes required as well. I was on a job where this was required as there was regular tractors near this area, and the owner of the existing pipe specified, also meant the new chamber had no flex in it with the older fixed pipes.