Welsh Water Build over agreement

[Adaminyei]

Hi all,

Thank you for reading this. I have applied for a build over agreement with Welsh Water and have just had a sewer trace performed. We propose to build near, but not over the public sewer at the rear of the property. As you can see from the attached plan that I've drawn post sewer trace, I'd like to build right up to one of the inspection chambers at the rear. The proposed foundations sit much further away and are all 580mm-1500mm from the sewer line.

I had initially requested that WW consider my proposal to decommission this manhole to allow us to build right up to where it currently sits. We have another chamber accessible on the same run, and our neighbours' to the left hand side of the sketch is also accessible and within 3 metres of our boundary. I am now wondering whether we could simplify things and propose to keep the manhole where is it, but still build right up to it.

- Has managed to get a water authority to give permission for the extension to go right up to the inspection chamber, whilst the foundations remain a good distance away? It will still be accessible from the outside of the property and would only ever pose a threat to us should it over flow.

- Does anyone have any advice for me in my discussions with Welsh Water?

I look forward to your comments,

Many thanks

A

 

[Murdochcat]

What do the Welsh Water guidelines state about proximity to new building works

 

[Adaminyei]

What do the Welsh Water guidelines state about proximity to new building works

Thanks, the guidelines state that buildings should be >500mm from inspection chambers and foundations >500mm from sewers. These are guidelines and not ‘rules’ as such. Any thoughts on my chances?

 

[^woody^]

What are those random grey hatched areas? Foundations? Are you catelevering the extension walls?

 

[Adaminyei]

What are those random grey hatched areas? Foundations? Are you catelevering the extension walls?

Yes the grey boxes with the green diagonal lines are the foundations and they are cantilevered, except for the one on the far left of the sketch. The main purpose of them being designed as such was to remain at far away from the sewer line as possible. The above ground extension however, in the orange line will sit right up to the inspection chamber cover (subject to permissions).

What are your thoughts?

 

[Adaminyei]

What are those random grey hatched areas? Foundations? Are you catelevering the extension walls?

Just re-read your comment and wonder if you mean the dashed lines - they are the existing walls of the house that will be coming down as part of the works

 

[^woody^]

The whole purpose of build over agreements and the legislation they come from is to protect the sewer pipe work and give access to them via the chambers. If you can demonstrate that, then an agreement should be given.

Bear in mind that typically the water authority's blurb mentions the location of the foundations to the pipework, and the location of the chambers to the walls. So that's what your design, and your design statement needs to address - which it looks like you could.

BTW, is there a self certification option that could be used?

 

[Adaminyei]

The whole purpose of build over agreements and the legislation they come from is to protect the sewer pipe work and give access to them via the chambers. If you can demonstrate that, then an agreement should be given.

Bear in mind that typically the water authority's blurb mentions the location of the foundations to the pipework, and the location of the chambers to the walls. So that's what your design, and your design statement needs to address - which it looks like you could.

BTW, is there a self certification option that could be used?

Thank you, and I hope that we can satisfy them with this proposal.

There is a self certification process, but not if we intend to build within 500mm of the inspection chamber access, which we are, or if the foundations sit within 500mm of the sewer.

If you have any other negotiating hints or tips, please let me know

 

[jono_h]

The Welsh Water guidance is pretty clear in that it’s a ‘No’ within 500mm and the accepted solutions are move the manhole or change the building design. And if you want to move the manhole you need to use their approved contractors.

When you say ‘right up to’ is that literally kissing the manhole? I self-certified with WW and made my extension slightly smaller in order to comply. In reality I pushed my luck as much as I thought I could and built to about 450mm. My BCO has never measured the distance between building & manhole, but was very particular that the new foundations were 150mm below invert. On the basis that he reports to WW that he’s satisfied, then if he’s happy everyone is happy.

 

[Adaminyei]

The Welsh Water guidance is pretty clear in that it’s a ‘No’ within 500mm and the accepted solutions are move the manhole or change the building design. And if you want to move the manhole you need to use their approved contractors.

When you say ‘right up to’ is that literally kissing the manhole? I self-certified with WW and made my extension slightly smaller in order to comply. In reality I pushed my luck as much as I thought I could and built to about 450mm. My BCO has never measured the distance between building & manhole, but was very particular that the new foundations were 150mm below invert. On the basis that he reports to WW that he’s satisfied, then if he’s happy everyone is happy.

Yes, the proposal is to have the build right up to the line of the chamber. however as this is where our sliding doors will be, they may not have to be right up to it.

As the sewer is actually off-set from the chamber slightly (see diagram), if we got permission to change that chamber to a rodding access point, that would give us the 500mm clearance. Any idea on whether changing a chamber to a rodding access point would be cheaper than decommissioning it and creating a new on elsewhere on the line?

 

[Murdochcat]

We had to deal with Thames Water and our SE managed to convince them that our piling could be nearer than their guidelines.

We had to pay to ACCURATELY map their sewer, pay for CCTV before AND after ........... and of course we had the SE's fees too

Is it a public sewer?

 

[noseall]

The whole purpose of build over agreements and the legislation they come from is to protect the sewer pipe work and give access to them via the chambers. If you can demonstrate that, then an agreement should be given.

Correct.

eyampipe3.jpg

• noseall
• 8 May 2023

eyampie2.jpg

• noseall
• 8 May 2023

20220713_102656.jpg

• noseall
• 19 Aug 2022

20220713_102709.jpg

• noseall
• 19 Aug 2022

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• noseall
• 19 Aug 2022

20220714_094859.jpg

• noseall
• 19 Aug 2022

20220715_090612.jpg

• noseall
• 19 Aug 2022

150mm clearance. Our IC is closer than recommended. It could not be sited anywhere other than where it is.

 

[Adaminyei]

Correct.

eyampipe3.jpg

• noseall
• 8 May 2023

eyampie2.jpg

• noseall
• 8 May 2023

20220713_102656.jpg

• noseall
• 19 Aug 2022

20220713_102709.jpg

• noseall
• 19 Aug 2022

20220713_122425.jpg

• noseall
• 19 Aug 2022

20220714_094859.jpg

• noseall
• 19 Aug 2022

20220715_090612.jpg

• noseall
• 19 Aug 2022

150mm clearance. Our IC is closer than recommended. It could not be sited anywhere other than where it is.

Thank you

 

[Adaminyei]

We had to deal with Thames Water and our SE managed to convince them that our piling could be nearer than their guidelines.

We had to pay to ACCURATELY map their sewer, pay for CCTV before AND after ........... and of course we had the SE's fees too

Is it a public sewer?

Yes it is a public sewer and I’ve had a CCTV survey trace done by Welsh Water.