Thames Water build over agreement for 823mm pipe

[Charan]

Hi, We are planning to build a games room over a Thames Water pipe which is 823mm. They (TW) wrote to me saying that i would need:

- A Pre condition survey has to be carried out before any works can start to understand the condition of asset. Once works complete a post condition survey is required. Both surveys are an additional cost to yourself.

- Location of sewer has to be confirmed by either exposing sewer in ground along length being built over or carrying out a sonde survey (this can be done whilst the Pre condition survey is being carried out). Location of sewer is essential so you do not disturb / hit sewer during your works.

Has anyone within the forum has had any experience of doing this and how much did cost?

Thanks in advance.

Charan

 

[SpecialK]

An 823mm diameter sewage pipe? How far underground is it?

 

[freddiemercurystwin]

823mm diameter! or do you mean that's the depth?

 

[Charan]

Special K,

Its a rainwater/surface pipe. and its 30cms (300mm) below the ground level surrounded by crushed concrete.

 

[Charan]

823mm diameter! or do you mean that's the depth?

diameter

 

[Charan]

823mm diameter! or do you mean that's the depth?

An 823mm diameter sewage pipe? How far underground is it?

not sewage pipe

 

[SpecialK]

diameter

Wow that's a monster. If it's only 300mm underground it should be easy enough to dig down either end to find out exactly where it's located. You can then draw that on a detailed plan and send it back to Thames water?

 

[noseall]

diameter

 

[freddiemercurystwin]

That's pretty big, the pipe may not be that deep but I suspect your pockets will need to be, that's well outside of standard self assessment buildover territory AFAIK and I think you may be looking at much longer process too. Are you sure it's actually where you think it is, the water board maps are notoriously inaccurate sometimes by tens of metres or more so that'd be the first thing to find out. I daresay someone will be along who's familiar with building over or near such beasts, assuming it's even permitted by Thames.

 

[freddiemercurystwin]

Special K,

Its a rainwater/surface pipe. and its 30cms (300mm) below the ground level surrounded by crushed concrete.

Have you uncovered it already then?

 

[jeds]

An 823mm pipe, 300mm below ground. Are you sure? What material is it made of? (Concrete) Where is the nearest access? (half a mile away)

 

[freddiemercurystwin]

It's all a bit odd, I daresay something has been lost in translation ....

 

[^woody^]

Are you sure you don't need permission from TFL instead?

 

[Charan]

Wow that's a monster. If it's only 300mm underground it should be easy enough to dig down either end to find out exactly where it's located. You can then draw that on a detailed plan and send it back to Thames water?

Thats what i plan to do

 

[Charan]

That's pretty big, the pipe may not be that deep but I suspect your pockets will need to be, that's well outside of standard self assessment buildover territory AFAIK and I think you may be looking at much longer process too. Are you sure it's actually where you think it is, the water board maps are notoriously inaccurate sometimes by tens of metres or more so that'd be the first thing to find out. I daresay someone will be along who's familiar with building over or near such beasts, assuming it's even permitted by Thames.

Thames do permit it. I submitted rough sketches prior to having professionally done by a structural engineer. They have agreed it in principle. and have said to undertake a pre and post condition survey.

The water board map is almost a few feet out as we happened to find a manhole 6 feet in the adjoining land. When opened it was carrying clear rainwater and there was no foul smell.