Shared manhole and rear extension

[Blueberries]

I will visit a detached bungalow this weekend that has a manhole near the conservatory. The owner confirmed it connects to the street in front and to a park at the back of the property. Here are some photos, you can see it on the left of the conservatory.

https://imgur.com/a/7kyM0ud

I called Anglian Water and they informed me that a 375mm diameter public foul water sewer is running through the land. I was planning on adding an extension, but my understanding is that the only solution would be to move this manhole and pipes with the consent of Anglian Water. Is that correct?
If you have been in a similar situation I would love to know whether you still decided to purchase the property and do your extension or thought it was too much of a risk.

 

[Wayners]

A family member sold a house as they were told they couldn't extend over the shared sewer that run up the side.
People that bought the house built a big extension over the sewer pipe. Go figure...

Seems to me if you get the planning application correct with agreements then its not a problem... sometimes.

 

[Blueberries]

A family member sold a house as they were told they couldn't extend over the shared sewer that run up the side.
People that bought the house built a big extension over the sewer pipe. Go figure...

Seems to me if you get the planning application correct with agreements then its not a problem... sometimes.

That’s… interesting! Do you know if your family member hired an architect that had good reputation for this kind of application? I’m so unsure what to do, it’s such a big risk to take!

 

[Wayners]

Contact a local architect and ask for advice. Probably have to pay a fee but they will advise. Then decide

 

[stevie888]

Different water companies have diferent rules concerning building over pipes so you may or may not be allowed to do that. Building over a chamber will be a definite no no. In theory they do a proper engineering assessment of your proposals

I got permission to build over a similar size sewer a few years back, (but did have some engineering challenges to overcome as a piled slab was required to bridge the pipe). No chambers involved

In that instance as the works were subject to planning permission which we got first as that was £206 whereas the build-over IIRC was £1200 or so. To have had PP refused after spending for a buildover

 

[freddiemercurystwin]

It's doubtful a build-over or build-near for a 375 sewer will ever be approved. But you should check Anglian Waters Build Over rules. Also you should be aware that water company maps are notoriously inaccurate often by many metres which can be a positive or a negative! So you should establish if, where and what size any sewers are before you go much further if your purchase hinges on being able to extend.

 

[Blueberries]

It's doubtful a build-over or build-near for a 375 sewer will ever be approved. But you should check Anglian Waters Build Over rules. Also you should be aware that water company maps are notoriously inaccurate often by many metres which can be a positive or a negative! So you should establish if, where and what size any sewers are before you go much further if your purchase hinges on being able to extend.

Thank you, I guess this can be determined with a CCTV survey of the drains, is that correct?

 

[Murdochcat]

Our experience with a build over and Thames Water

Builder located inspection chamber under about 15 inches of soil

Builder called in BCO who put immediate stop on job

I contacted Thames Water who then requested proper drawings showing the size, depth and locations of all the pipes

We then paid the SE to work with Thames Water and redesign our piled foundation’s

And we also had pay Thames Water to send a team around with CCTV to survey and record their findings

Our inspection chamber and all the pipes couldn’t be moved and the inspection chamber couldn’t be inside the extension which meant modifying the garage and utility room designs

Once Thames water had all the above agreed they issued the build over agreement and this was submitted to the BCO before the build could recommence

Extremely expensive, caused months of delays and the final horror was that even though we are detached we needed to also pay the party wall agreement for our neighbours

Our entire contingency was spent on the extras above

An experience not to want to go through ever again

 

[freddiemercurystwin]

Thank you, I guess this can be determined with a CCTV survey of the drains, is that correct?

A good (one man band ) type of drain surveyor is what need (unless you're savvy enough yourself) they'll need to be able to produce a simple site plan showing where the drains are, what size/material etc within your boundary or up 3m away from any potential extensions, a CCTV will be required by the Anglian in any case. But if there's a handy manhole within 3m and it's a bigger sewer than their rules permit then it's a no no anyway.

 

[Blueberries]

A good (one man band ) type of drain surveyor is what need (unless you're savvy enough yourself) they'll need to be able to produce a simple site plan showing where the drains are, what size/material etc within your boundary or up 3m away from any potential extensions, a CCTV will be required by the Anglian in any case. But if there's a handy manhole within 3m and it's a bigger sewer than their rules permit then it's a no no anyway.

Thank you, may be worth asking the current owners if they have this info from when they purchased the property. I think the manhole could be moved, but I am not finding much info about the 375mm pipes on the Anglian website (only mentions 160mm)

 

[noseall]

I think the manhole could be moved, but I am not finding much info about the 375mm pipes on the Anglian website (only mentions 160mm)

Most builders would run a mile from 375mm pipe. 160mm is scarce. Impossible for a regular trades to get off the shelf stuff of that size. You may be lucky and find a civils company that will take on the drainage but they will be very expensive compared to regular trades price.

 

[Blueberries]

Most builders would run a mile from 375mm pipe. 160mm is scarce. Impossible for a regular trades to get off the shelf stuff of that size. You may be lucky and find a civils company that will take on the drainage but they will be very expensive compared to regular trades price.

Sigh! Thanks, I guess I will have to let go of this house then, what a shame! Massive garden, detached, in a nice location, but the house is too small for our needs. Any idea how they managed to build that conservatory so close to the manhole? Clearly it is less than 3 meters from it.

 

[noseall]

Any idea how they managed to build that conservatory so close to the manhole? Clearly it is less than 3 meters from it.

Connie companies are ignorant of such things as drains and foundations depths and Building Control, lol.

 

[freddiemercurystwin]

Because years ago it wasn't really in the mind of homeowners and conservatory builders don't care as typically conservatories aren't subject to Building Control approval so no inspections. It might still be worth having a gander about to see if you can lift a manhole to determine the size/depth/rough direction. As mentioned the maps are often woefully inaccurate.

 

[Blueberries]

Because years ago it wasn't really in the mind of homeowners and conservatory builders don't care as typically conservatories aren't subject to Building Control approval so no inspections. It might still be worth having a gander about to see if you can lift a manhole to determine the size/depth/rough direction. As mentioned the maps are often woefully inaccurate.

Yes we will have a look and see if we can understand. Gosh I wish my dad was still here, he was the best to give this type of advice.