Build over agreement rejected?

[noseall]

Footings are the standard depth though but they flat out refuse to let you build within 3m of their 5m deep pipe, it's ridiculous really.

They are considering the 'angle of repose' and so should you, with those impressive depths involved.

I've not studied the thread, but are there any proposed extension walls, that will be parallel to the deep pipe and what will be their distance from it?

 

[SD73]

They are considering the 'angle of repose' and so should you, with those impressive depths involved.

I've not studied the thread, but are there any proposed extension walls, that will be parallel to the deep pipe and what will be their distance from it?

Yeah the rear wall into the garden will run parallel to it, it's currently 1.9m from the pipe, however we wanted to go out another 1m so would end up 900mm away but it seems they have a blanket NO against that as we would be within 3m, regardless of the fact the existing wall is already within that distance.

I'm going to consult building control and my structural engineer to see if we can pile and put down some RSJ as a platform to build onto as a workaround

 

[noseall]

Yeah the rear wall into the garden will run parallel to it, it's currently 1.9m from the pipe, however we wanted to go out another 1m so would end up 900mm away but it seems they have a blanket NO against that as we would be within 3m, regardless of the fact the existing wall is already within that distance.

I'm going to consult building control and my structural engineer to see if we can pile and put down some RSJ as a platform to build onto as a workaround

You do realise the depth you'd need to go, don't you?

 

[SD73]

You do realise the depth you'd need to go, don't you?

Nope I work in IT I'm not a builder lol, our fallback option is to change the extension to go out either side rather than further into the garden, that's looking increasingly likely, however it should be possible under permitted development

 

[jeds]

The only option for 5m deep is a piled footing.

 

[wessex101]

Something doesn't add up here. Initially the OP was saying "as the extension will be over the top of the existing sewer manhole" They then went on to say the sewer is about 2 m deep and the builder had dug a trench from the manhole in an attempt to trace the drain run. Why not just look down the manhole? Are you getter "sewer" and "drain" mixed up by any chance?
The latest revelation that the sewer is in fact 5 metres deep is extremely unusual. Unless it is a main trunk sewer why on earth would they put it 5 metres underground, that makes no sense. Exactly how was that depth established and why did it take so long to find this out if there was a manhole on the sewer the whole time?
In my dealings with the water companies I find that their information on the location and depth of sewers is extremely sketchy, they have only a vague idea of roughly where they run and how deep. When you make your build over application it is therefore preferable to have already confirmed the exact position and depth of the sewer so you are not at the mercy of their vague and haphazard assumptions.

 

[SD73]

Something doesn't add up here. Initially the OP was saying "as the extension will be over the top of the existing sewer manhole" They then went on to say the sewer is about 2 m deep and the builder had dug a trench from the manhole in an attempt to trace the drain run. Why not just look down the manhole? Are you getter "sewer" and "drain" mixed up by any chance?
The latest revelation that the sewer is in fact 5 metres deep is extremely unusual. Unless it is a main trunk sewer why on earth would they put it 5 metres underground, that makes no sense. Exactly how was that depth established and why did it take so long to find this out if there was a manhole on the sewer the whole time?
In my dealings with the water companies I find that their information on the location and depth of sewers is extremely sketchy, they have only a vague idea of roughly where they run and how deep. When you make your build over application it is therefore preferable to have already confirmed the exact position and depth of the sewer so you are not at the mercy of their vague and haphazard assumptions.

Ok to answer the above, we was totally unaware of the sewer location, again I'm not a specialist in these matters, to me the manhole is the sewer, however now I know a bit more I can provide some clarity.

We have a rear extension that sticks out roughly 4m and is approx 3m wide, to the side of this around 200mm is the manhole, this manhole has a pipe that connects down to the sewer main which is approx 5m deep and 1.9m from the rear of the extension into the garden.

I now know all of this as we have had a CCTV and Sonde survey done and they have mapped the sewer for us, as you say SW records are extremely sketchy, their plan shows the sewer main actually under our extension where as in reality it's almost 2m away from it.

SW refuse the build over as the sewer is deemed Critical by depth as it's approx 5m deep, and your not allowed to build within 3m of that.

So we are trying to assess our options, someone has mentioned piling, my other option is to bring the extension on the side back by 1.1m so I'm on the edge of their 3m rule and thus dont need a build over agreement I believe?

Additionally to this I can also build on the other side of the extension as it's less than 3m as permitted development to get back some of the space I will be losing by not being able to go with the original plan.

The only question I really now have for SW is if I can remove the manhole completely, join our new waste to the existing connection with a rubber sleeve and put a rodding point in for access, thats the only question they are avoiding totally right now as they are fixated with this critical main sewer and wanting me to stump up tens of thousands to divert it.

The whole thing is a mess and a nightmare, and it's dragging on and on, Im at the point I just want a solid decision so I can adjust our plans accordingly

 

[noseall]

The only option for 5m deep is a piled footing.

I dread to think what the made-up ground situation is like, on a site with 5m drains.

Pile and beam is the only solution I can see.

 

[SD73]

Update, I have spoken to an escalation manager at SW, we have discussed options.

1. We dig down 150mm below the pipe, add reinforcing and pour ontop of that, sounds expensive.

2. We come back 1m, drive piles 150mm below pipe level, put a ring beam in and build ontop of that.

3. Not go any further towards the pipe, and dig 2m footings and build to that.

Option 3 seems the most likely, additionally as we was only extending one side of the property, we can actually extend both, as the other side would fall within permitted development, so the loss of space going into the garden would be offset with the additional space to the side

 

[noseall]

Update, I have spoken to an escalation manager at SW, we have discussed options.

1. We dig down 150mm below the pipe, add reinforcing and pour ontop of that, sounds expensive.

2. We come back 1m, drive piles 150mm below pipe level, put a ring beam in and build ontop of that.

3. Not go any further towards the pipe, and dig 2m footings and build to that.

Option 3 seems the most likely, additionally as we was only extending one side of the property, we can actually extend both, as the other side would fall within permitted development, so the loss of space going into the garden would be offset with the additional space to the side

What has your designer said about all this?

 

[noseall]

3. Not go any further towards the pipe, and dig 2m footings and build to that.

What distance form the pipe will this wall position be?

 

[SD73]

What distance form the pipe will this wall position be?

1.9m

 

[noseall]

1.9m

The angle of repose dictates you'll have to go down in excess of 3 meters. This will be a Building Control/design decision. It's going to be a pile & beam, which ever way you look at it.

 

[SD73]

The angle of repose dictates you'll have to go down in excess of 3 meters. This will be a Building Control/design decision. It's going to be a pile & beam, which ever way you look at it.

The guy from SW has agreed a 2m footing as we're 1.9 from the pipe on the existing building as long as we keep the side extensions at the same distance from their pipe, I'm happy with that.

 

[noseall]

The guy from SW has agreed a 2m footing

Irrelevant. Building Control, structural engineers and guidance will tell you the correct way. If your trench is within 1.9m of a 5m deep dig, then you'll likely have to go beyond 3m. Probably more.