building near private water drain

samad1st

hi...iv bought a house with the sole purpose of extending it.iv got planning permission for a two story extension to the side of the property.my work has started but held up due to discovery of a private manhole just millimetres from the rear of my proposed extension wall.iv found out it belongs to the council,is about 10 metres deep,and has water going through.iv contacted environmental health and am waiting for a reply if i can build close to or maybe a few feets back.Does anyone know if they will allow me to continue building or refuse to build? my building control officer will not let me continue until we have a reply from council

mcooke999

Firstly, a 10m deep drain is very serious. This is not something you can just ignore or build over or near in the traditional sense (i.e.: traditional strip foundations).

You need to ascertain ownership of the drain. You say it's private (i.e.: you own it) but then you've said the 'council' owns it? I think you mean your local water authority when you say the council? Am I correct? If so then you will need to obtain permission to build over the drain by them, however, at 10m deep you're probably going to find it very difficult to do without accepting you're going to have probably pile the extension, or divert the drain.

You won't be allowed to build 'a few feet away' as you say because at 10m deep, your foundations would be transfering load onto the drain, plus the water authority wouldn't be able to safely access the drain (10m deep = massive hole)...

Have you got any drawings of your extension showing the approx position of the drain on plan and I'll be able to help a bit more.

Also, please let me know what area you are in so I can see who your local water authority is.

samad1st

hi thanks for help,we where initially directed to united utilities by oldham council,which after searches found out it belongs to my lease holder,which are oldham council.i am more than happy to pile as long as i can build.i dont think diverting the drain will be possible.would piling near manhole cause damage to the drain?the drain does not run under the proposed extension but does run close to it.i will try and upload some drawings as soon as i can find out how! really appreciate the help guys

samad1st

water/drain marked in blue

mcooke999

Cheers, it definitely is possible with a piled foundation solution! I've sent you a private message about it...

DOH_a

Gees, somebody has missed out some crucial research into the existing services prior to Planning/Building Regulation approvals!!!

Foundations should be taken to at least the invert level of any adjacent drains. Assuming you may have had traditional strip/trench fill foundations at 1m deep priced, 10m deep pile foundations are going to be considerably expensive. If new foundations have already been excavated, you may well have to remove those and go for a complete pile and ground beam design, which is undertaken by a specialist. I would however check the water authority’s rules and regulations of excavating near public sewers as some don’t allow pile foundations that close. This is on the understanding it is a public and not private sewer.

Davesnave

Are you sure about the 10m? It's not impossible, of course, but that's ***** deep and there would have to be a good reason for it.

mcooke999

The owners first step is to write to the Water Authority (United Utilities in this case) to determine what information they will require in order to allow you to build near the sewer. Note that this could be a slow process. At the end of the day, the pipe is UU's property and it's their duty to make sure that no one builds anything nearby that would have any negative implications (i.e.: directly cause damage or otherwise prevent future access to the pipe)... UU will ask you to submit drawings showing your proposals and will want to see copy of the foundation design drawings & calculations to allow them to ensure what you're proposing is OK. They may even want to carry out site visits whilst you are undertaking the foundation works to ensure that what is being constructed is in line with what you've told them you're doing.

Ultimately though the outcome of the above process will result in either not going ahead with the extension (either due to cost or simply UU won't let you do it) or installing piled foundations instead, with an easement zone either size of the pipe where piles are not allowed to be installed (This dimension varies from water authority to water authority but depends on the depth of the pipe also)... As the pipe is so close to the new extension, any easement is effectively going to require you to have the rear portion of the extension on foundations which are cantilevered (not impossible and common in this situation) however, depending on the size of the easement this may or may not be feasilble without also reducing how far down the side of the existing property you are extending (i.e.: reducing the 7.3m dimension to help reduce or eliminate this cantilever).

So in summary, it is possible, however, it's going to cost more than traditional strip foundations and take longer due to the added headache of having to deal with UU... good luck and let me know if you need any further information / designs!

samad1st

Thanks all for msgs...after a long and painful week of contacting the council, united utilities, environmental health, building control, and then the council again, the council has confirmed that I am the riparian owner of the manhole and any drain running under my property! The council will not object to any work as long as the drain is not damaged and have advised that I get structural engineer report before any work is done. My builder is on to it and thank you mcooke99 for your help.

samad1st

 and it was 22 feet deep sorry!!

DOH_a

6.6m is still a bladdy deep manhole. I assume there are some internal iron steps for access and is it a backdrop manhole?