Need Some Advice reg 225mm Public Sewers in my property

[Scorpi]

Hi guys, we bought a old 1930s detached property we knew that it would require work and we had the idea to build a double storey extension on the side.

I recently instructed a architect in this matter, we knew there was a sewer running but never knew how it would affect us (naivety..).

This is the reply ST Water gave to our architects query whether there were any public sewers running through our land:

"
Having reviewed our statutory sewer records, they demonstrate the following sewer with associated protective strip:

225mm foul sewer and 225mm surface water sewer


225mm diameter surface water sewer – with a protective strip of 3m either side of the pipe, thus providing 6m across the diameter to the pipe"

One of the architects team said it may be difficult to get STW to give me permission(they havent even asked!), after an email and phone call for a proper explanation he said he would contact me on Monday. I dont understand the flippant answer given by the architect.

From reading stuff on here and the internet it seems I need a Build Over agreement, is there any reason why this would not be granted?

I have attached a diagram. The property with red dot is mine. The foul drain runs under a existing neighbours extension and a previous garage which has now been demolished on my property. So I dont know how that would be a problem.

The surface water drain (in blue) seems to be the issue, however there may have been a building here in the past. Currently it is a semi permanent building (no sides just a temporary roof). According to there plans however there is a structure over it. This is where I wanted the double storey extension.

I am awaiting the phone call on Monday from the architect but it has put all my plans in disarray, from looking at my land it doesnt seem as if ever there has been any attempt to maintain the sewer from my land. The ground does not seem disturbed at all and is very old.

If I were to ask for a BOA would it be likely granted? And if not how much would I need to spend to divert the sewer so it runs parallel to the foul drain?

Really in a pickle here, unsure how to proceed.

 

[John D v2.0]

225mm is quite a big one, standard domestic one that picks up several houses would be 100mm or 4 inch, this is over 5 times the area so it must cover the whole estate.
Even for 150mm ones you usually have to put a camera in before and after to confirm nothing is affected.
For yours the size means if it blocked or collapsed it would be pretty urgent to get it dug up and repaired. You wouldn't want it to be your extension getting dug up. The clearance zone is to get the diggers and heavy machinery in.

Hope you can find a solution. If you're keen you can talk to the water company directly and see what flexibility there is.

 

[freddiemercurystwin]

Severn Trent Water? Do you actually know where the drain runs are? You need to find out if not, you cannot rely on the maps they're often notoriously inaccurate, by many metres or more sometimes.

 

[Scorpi]

Severn Trent Water? Do you actually know where the drain runs are? You need to find out if not, you cannot rely on the maps they're often notoriously inaccurate, by many metres or more sometimes.

Yes its severn trent. No I cant see any drains on that side of my property where the pipes supposedly run.

However I did see one just outside my main house in my rear garden. I may take some pictures, as im not very good at these things.

 

[Scorpi]

I just noticed this from the surveyors report

"The rear extension and conservatory appear to have been built over a drain. The extension, however, appears to have
been built before the need for a Build Over Agreement with the local water company"

This is directly behind my house. Could the sewer infact be running under my house or is it a seperate drain? even more confused now.

 

[Scorpi]

Yes its severn trent. No I cant see any drains on that side of my property where the pipes supposedly run.

However I did see one just outside my main house in my rear garden. I may take some pictures, as im not very good at these things.

Thats the rear conservatory and that wall to the left is where I want the extension. Is that drain where a green pipe is coming out of a manhole cover?

 

[jeds]

The 3-6m thing doesn't mean you can't build over a sewer - it just means anything within must be agreed before you start work. Buildover agreements aren't normally a problem but a lot depends on whether the sewer is classed as 'strategic'? These are normally 300mm and above but a 225 sewer can be strategic depending on the number of properties that rely on it. Overall this looks like standard build-over application to me.

 

[freddiemercurystwin]

Yes as above and change your architect's, they sound clueless, architects are overkill for an extension anyway, look for an architectural technician or perhaps a one man band architect at the most rather than a firm.

You won't be able to see the drains they're underground! Some detective work is in order by whoever you employ.

 

[thomp1983]

All the information for severn trent build over agreements is available on there website, have a look and see if you comply.

 

[Scorpi]

All the information for severn trent build over agreements is available on there website, have a look and see if you comply.

Yes, I can see the option for 225mm sewer build over agreement. I think I'll have to contact ST water and find out if I need a class 2 or 3 application.

Also need to find somebody decent in the Birmingham area to help me do this, this architect getting the sack monday.

 

[Scorpi]

Well I got a new architect, they seem alot more professional. First job is to find out the depth of the existing sewer pipe.

Got drainage survey in on monday, will tell them to also check neighbours manhole. I think its the foul water one.

No manholes in my property.

And if the manholes in the roads are anything to go by, it looks like the foul water one is barely running through my property.

The manhole for it is not where it is in the maps, its in the corner of my property. So that one might not be a problem.

Architect did say we need to construct manholes in my garden, am dreading the costs of this extension. I think easily 5-10k extra due to this hassle.

 

[thomp1983]

10k extra for drain works, you need to get your sleeves rolled up not your pants pulled down, when we did our drains I looked for a man with a digger who ended up costing me £700 a week, he dug the trenches and we laid the pipework between us.

Took 2 weeks and the pipework, inspection chambers and fittings cost about £700 and then £200 for a grab lorry, we laid 15m in an L shape around the property for my new drains from the extension and also replaced a clay drain that runs about 9m across the property under the new extension that serves the rest of the houses in the street. Parts of our drains were 2m deep so some proper work, there's some pictures around here somewhere.

I could have saved money by hiring my own digger but that would probably have cost me another week in time getting up to speed with the digger and doing it all on my own.

 

[freddiemercurystwin]

What a way with words you have thom, I daresay it may not be as expensive as the OP suspects, that said (I can't say for STW) but Southwest Water water certainly like to charge handsomely for tapping into their system with new mh's.

 

[thomp1983]

Severn trent came out during our drain works and inspected due to difficult neighbours.

Ironically the inspector said there was no way they'd of dug down to 2m plus to join at invert level, they'd of used a back drop into the existing manhole which there build over agreement terms online prohibit.

I found them easy to deal with but the advantage I had was having 2 inspection chambers on the property meant I knew exactly where the existing drains were before starting work so I could easily draw a plan, the op may well have to do some digging or as suggested use a cctv survey to work out where things are on their land.

 

[Scorpi]

Digging didnt do the job, 2.2 metre down we dug and 2 metre wide in the front garden where the sewer is supposed to be according to diagrams.

Found nowt. Cost £270 not as much as I thought it would, one day digger and driver hire.

We opened the manhole in the road(3.3M Deep). From the direction of the flow of the water in the manhole it is difficult to ascertain exactly where it goes through my property. I initially thought it might have went in the neighbours, but I dont know how sewers work.

Ive attached a picture, is it possible for that sewer run to turn 45+ degrees to the right after say 5/6 metres?

Anyway water cant flow up, it only flows down or straight so that means if it does go under my proposed site of extension its 3.3M or more deep!

If that runs through my proposed site of extension I dont know what I can do to satisfy STW Build over team. I cant dig that deep right next to my house, it would put the foundations at risk.

So ive ordered a CCTV survey, another week of waiting till they arrive. All im doing is looking at pictures of the manhole all day and guessing where it goes..