Building over class 3 public sewer

[Tom99999]

We've recently applied to Severn Trent to build over a class 3 public sewer running though our property. The sewer is 525mm diameter and at a depth of 2.4m. The manhole access for this run of sewer pipe is in next door's back garden.

We've fulfilled the application criteria and have had a CCTV survey of the sewer pipe which showed no signs of deterioration. The houses in the road and presumably the sewer was constructed in 1967. There is currently a conservatory and garage which are over or very near to the existing sewer pipe on our property. The proposed plans include demolishing the existing conservatory and garage and replacing these with a two storey side and rear extension (see plans attached).

As requested we've discussed with Severn Trent several times before submitting our application and were assured that it shouldn't be a problem. They've advised of the typical solution to building over sewers and we've included these in our plans which were submitted.

They've just come back and refused our application on the grounds that they need to maintain access to allow for future maintenance of the sewer system.

I've submitted a letter to they asking them to review and re-consider the application, as well as pointing our to them that the access to the drain already is restricted because of our garage and conservatory. I've also asked they to suggest a workable solution to allow us to build over this sewer. They've yet to get back to us (but it's only been 1 day!).

Questions:
is there likely to be a workable and cost effective solution to this?
What are the questions that I need to ask both my builder/architect and Severn Trent.

 

[^woody^]

Really, your Architect should be sorting this out - or rather should have sorted it out right at the start

The WA (ie ST) has a duty to protect the sewer, but they interpret this widely. If you have a suitable design so as not to affect the sewer then this should be adequate It is arguable if the company can legitimately refuse a build over agreement on the basis of maybe needing future access to someones back garden - especially when it is common for other buildings to be already built over sewers

You can use the WA's complaints system and then complain to the Consumer Council for Water. Or see a Solicitor. Either way, this could get really expensive

But you need to develop a constructive argument to present to the WA, else you will get a standard scripted reply

 

[Tom99999]

Really, your Architect should be sorting this out - or rather should have sorted it out right at the start

The WA (ie ST) has a duty to protect the sewer, but they interpret this widely. If you have a suitable design so as not to affect the sewer then this should be adequate It is arguable if the company can legitimately refuse a build over agreement on the basis of maybe needing future access to someones back garden - especially when it is common for other buildings to be already built over sewers

You can use the WA's complaints system and then complain to the Consumer Council for Water. Or see a Solicitor. Either way, this could get really expensive

But you need to develop a constructive argument to present to the WA, else you will get a standard scripted reply

Thanks for your advise.

Yes, architect has worked up the plans on the basis of the advise that we've been given by ST before we submitted the plans. This was on the basis that the footings would be dug down to the invert of the sewer on either side and then bridged using a concrete lintel arrangement. We spoke to ST several times, and they all intimated that 'it wouldn't be a problem'.

We've then had a very brief and un-helpful stock reply to the application. It begs the question - why even apply when the stock answer is going to be no!?!?

"Thank you for your application to build over the 525mm public foul sewer.

Unfortunately, we are unable to approve your proposals. To maintain essential access for maintenance, repair, renewal and to protect the structural integrity of the public sewerage system, no building shall be erected or trees planted within 5 metres of this sewer."

Will have to see what they say to our letter asking them to review the application again, and provide some more advise as to what was wrong with the application, and what solution we could come up with that they would be satisfied with.

 

[maltaron]

Be prepared for a fight, and do not rely on Consumer Council for Water, Ofwat or any other quango. I recently had a similar problem (only for a 4" pipe). Initially South West Water told my architect by telephone that "we will inspect the pipe and if it needs replacing we will pay for this". After the CCTV survey they it was found that it was a pitch fibre pipe. After gaining planning permision I requested a build over approval and was told that I must pay for the pipe to be replaced with malleable iron at a cost of around £8500.00. I argued that they had said that they would pay if the pipe needed repacement, which it did as it was pitch fibre with a life of 30yrs. After a file full of letters and e-mails and denials that the original phone call had ever taken place, a solicitors letter finally forced an admittance that the phone call had ocurred as stated but still they insisted that I must pay. I then sent a letter direct to the CEO of South west water and offered £2000.00 towards the cost of replacing the pipe(this as insurance against any problems with the sewer) and saying that if he did not accept this I would instigate court action under the law of Prommissary Estopple. I sent the letter first class post and the following afternoon received a phone call that they accepted my offer. I now have my extension all finished in the knowledge that the sewer will not need any attention for upwards of 100 yrs. I am now waiting to have half of my garden dug up to replace the rest of the pitch fibre, which is now 15 years past its sellby date.

 

[Tom99999]

Well, our fears of Severn Trent being awkward has not materialised. Our initial application was denied, where they cited they wouldn't allow building over the sewer as they needed to maintain access for future maintenance. However, this was a standard answer, and after an email reply to ST, and getting the manager to review the case again, they did a total u-turn on the decision and replied the same day with the approval to go ahead!

We've subsequently has to re-design the foundations as digging down to 2.4mtrs to the invert of the sewer was not feasible once the builder had started, and would hve resulted in having to underpin the whole of next door's property which would have been far too expensive and risky. We subsequently employed a structural engineer and have re-designed foundations to be a 'raft' using steel reinforced concrete which will sit over the top of the sewer but only goes down 600mm into the ground at the deepest point, and will spread the load over the whole footprint of the extension.

We contacted Severn Trent with our predicament and submitted revised drawing for foundation as well as pages of structural calculations. Thankfully severn Trent approved the change of design within 24 hrs so hasn't held up the building works too much.

 

[noseall]

A 2.4m deep and 0.5m wide pipe will have had one heck of a trench dug out originally, when laying said pipe. That is a lot of disturbed ground.

In which case, is a raft wise for a two storey and not say mini piles?

 

[Sami_claire]

Can I ask for your help- we are in the same situation where we have no option (due to refused council planning permission to go beyond 3m) but to build directly on foul and storm drains.

We have been refused twice now to build on them by severn trent, even though the pipes have been replaced (they were damaged) following cctv, concrete lintels and all in accordance with their own instructions and following advice from our structural engineer and building inspector. Their response was that they never allow such permission for anyone.

Can I ask what you wrote in your appeal to see if we can put a complaint In?
We are at a total loss what to do as we have knocked down our old kitchen already!

 

[noseall]

You can not build directly over the pipe.

P.S. Start a new thread.