Building near pressurised sewer

[thomp1983]

Hi all,

Does anyone have experience of building near a pressurised sewer?

I had planning passed last week for a double garage with rooms above on my corner plot, the guy in the street behind me has the same approval he got his a couple of weeks before me.

He started digging out all his foundations and yesterday received an email from severn trent telling him he had to cease works as there is a pressurised sewer running at the border of our properties and he can't build within 5 metres of it and that there is an easement in place.

The neighbour informed me of this yesterday, I've not had any news from severn trent yet but im slightly behind him, he asked severn trent for the exact location of the sewer but they don't have any records it's just somewhere near where indicated on the plan, neither my solicitor or his found any easement in place when buying the properties, so if we wish to build anything are we able to just use the location on there plan to measure from or is one of us going to have to swallow the cost of digging upto 3 metres or more without damaging said sewer so we can work out exactly where we can build?

Oddly the house between our properties which is also a corner plot has had an extension built in the 90's which is clearly closer than 5m to this sewer yet they must of had the same easement on their property.

Anyone any advice?

Thanks
Chris

 

[SpecialK]

Give them a ring and see if they can provide a copy of the sewers location - they may charge for an official version but may give you an idea over the phone? Perhaps they can also provide a copy of the easement?

Did you receive a copy of the drainage search when you purchased?

 

[thomp1983]

Hi, yes we both received copies of the drain searches, his shows no issues or easements, mine has a drain flagged up that runs diagnolly across my property which I've a build over agreement application in for to move, I'm expecting the outcome of that application to be I can't build due to this pressurised sewer.

Unfortunately due to covid you can't ring them, the neighbour has had several emails with them which result in the drains map is just an approximate guide we don't have anything more accurate and you can't build within 5m of this sewer no one knows the location or depth of.

I'm currently not contacting severn trent in the hope my application may slip through and they sign off my build over agreement and which point ill be getting my extension at that side thrown up double quick time, the only issue I have is I'm sure the neighbour will be straight onto severn trent if I get the go ahead complaining at which point they would probably then try and stop me building.

I can still build something worthwhile if the drain is where it shows on there plan, if its closer to my house then it's probably not worth it but obviously if it's further away then every bit I can gain helps, I thought this morning I may ring a few groundwork companies and see if I can find anyone with a really long auger that would be willing to dig a few test holes to determine the depth of the sewer but obviously there's a risk of damaging the sewer, I'd hope the sewer would be marked in the ground a safe distance before you reach it like electricity cables are.

Thanks
Chris

 

[freddiemercurystwin]

Water company maps are notoriously inaccurate and a survey to determine their position is always required it could easily be several m's away in either direction from where the map shows. They don't find drains using an augur, if there are no manholes or other tell tale signs they can do a sonar tracing survey. But not a ground worker you need a drain surveyor.

 

[thomp1983]

It's a pressurised sewer so there are no access points or manholes to suggest it's location, the neighbour spoke to a drain surveyor and its £1500 for a survey with no guarantees they'll be able to locate it if its at 3m or more depth and there's no refund for finding nothing,

If the neighbour will split the cost we will probably have to give it a go but as I said I'm still waiting for severn trent to raise the issue with me.

So apart from a sonar survey and digging for it are there any other ways of finding it?

 

[Hugh Jaleak]

I can only echo Freddie's comments above, ironically I was on a job recently where the 'Rising Main' (that's the pumping main from the Pump Station to the discharge point), had split, the dig team had managed to locate it, (that was the easy bit as the leak had given it away!), but were still struggling to ascertain exactly where it was damaged, so asked for the pumps to be turned back on so they could tell more.

I suspect a Sonar survey would be difficult, and expensive. The pumps would have to be turned off whilst the survey is done, and unlike other services, sewers cannot be shut down, the flow has to be taken care of by other methods, either overpumping or tankering. Then assumes the line can be accessed and the sonar introduced to travel to the required point and a signal found to establish the location. Some can also be extremely deep, so not the sort of job you'd want to do on a weekend with a 1 tonne mini digger.

Very highly unlikely it is marked, and unless you know the pipe material I would steer well clear. Often older pipes are ductile iron or asbestos cement, and depending on diameter and distance, the pressure within could be quite high.

I would also be very careful about trying to get one over on Severn Trent. Water Companies have deep pockets and good Lawyers.

 

[thomp1983]

So the short version is theres zero practical way of finding it and if severn trent won't allow us to use the location on there map then we can't build anything?

 

[bernardgreen]

The advice from Freddie and Hugh is the best advice.

if severn trent won't allow us to use the location on there map then we can't build anything?

Personally I would not want to build anything close to a pressurised sewer line. We have had two leaks in the pipe from the village sewer pumping station. Both leaks were under fields and resulted in sewage liquor was ouzzing out of several square metres of land.

 

[SpecialK]

Ask your solicitor where you stand if there is no easement in place?

So the short version is theres zero practical way of finding it and if severn trent won't allow us to use the location on there map then we can't build anything?

 

[Hugh Jaleak]

So the short version is theres zero practical way of finding it and if severn trent won't allow us to use the location on there map then we can't build anything?

Probably about the size of it yes. You really wouldn't want to build on top of it, as if it goes tits up, yes the pipe can be repaired, and diverted if need be, but these things make an unholy mess, and cleaning up after it isn't pleasant. May also cause a void in the ground, which in turn could weaken the foundations of your new extension. Hopefully the corner plot will not have to find out.

Could ask if there's any plans in the 'pipeline' to move it, given it's not ideal running through residential properties, but given that is not going to be cheap, ST are unlikely to do anything unless they are forced to. Really should have been picked up when you bought the property, if Severn Trent have it on their maps, then it was known about. Someone didn't look properly.....

 

[thomp1983]

Sorry something may have been lost over the Internet, neither of us plan to bud over the pressurised sewer, both our foundations will finish about 2.5 meters away from the pressurised sewer providing its where they say it is.

Solicitors are not saying anything and let's face it attempting to sue a solicitor wl be more hassle than it's worth, what I need to do is find a practical solution to finding the sewer and right now hand digging a massive supported trench in my garden looks like the only remotely viable option

 

[Hugh Jaleak]

Understand you're not building directly over it, but several metres wayleave under, over and either side is usually expected to avoid any risk of damage to the asset. 2.5metres may still be too close if they're not happy with the situation. Have you actually seen a copy of the mapping, and do you know the size of the pipe? A smaller pipe is going to be a lot easier to work with/around than a 300+mm iron main.

I would really take a long hard think about whether it is viable to do this extension, or whether your energies and finances may be better put into another idea. Could be an awful lot of digging just to find the job is a non starter.

 

[thomp1983]

I'll put the drain map up I have later

 

[thomp1983]

that's the drain map from severn trent that we both have, the orange dotted line is the pressurised sewer in question, its a 100mm pvc pipe.

that's my proposed build, moving the red drain to the blue position is the reason I've a build over request in with severn trent, between the fence in this picture and the yellow line of my extension wall is 2.5m.

that's the layout of what I'm wanting to build, now if severn trent were to say the drain is on that fence line and I cant build within 5m of it then that's fine I'll bring my double garage into to 3.6m width instead of 6m and rejig the wc and utility room into other areas and be happy as I can be given the situation but I need to know where that pipe is and severn trent are being unhelpful.

I mean if they said for 20k they'd move the pipe then me and the neighbour would split it and get on with it but their refusing to entertain any conversation around the sewer their just stopping at there's a sewer there somewhere so were stopping your build and its tough luck.

thanks
Chris

one other thing of note I've just remembered, if I stand on the footpath that borders my house straight down the middle of it is a 200mm wide section of the path that's been dug up and relaid at some point, is this likely to be the sewer in question or is there something else likely to be buried under the footpath

 

[SpecialK]

If there is no eavesment how can they stop you building?