underground soil pipe

[jpread988]

hi all,

need to install a new soil pipe run, is going into the existing manhole 90 degrees to the flow okay?? see picture for clarification,

and i right in thinking the the fall for such a pipe is 1:40?

will i need to install some kind of pea single under the pipe or on top of it?

and can i just core through the side of the manhole wall poke the pipe though and cement around it or is there a special adapter that connects to the plastic pipe to fot to the wall of the manhole?

thanks for any help given

 

[Hugh Jaleak]

Foul connection should sweep into the channel in the direction of flow, as close to the existing invert (level of the pipe) as possible. It is important to get a foul connection correct or problems may soon arise with solid matter building up to potentially cause a blockage. Bends are allowed immediately outside the chamber, further along the run, then another chamber is needed.

1:40 is rule of thumb, may get away with less if needed. Pipe should be bedded on peagravel, once desired fall is achieved, surround the pipe with more peagravel, then selected backfill initially, (no large lumps or stones in the first layer.) Not sure what you mean by an 'elephants foot', the correct method is to use a rest bend at the base of a stack.

Wealth of good info to be found here: http://www.pavingexpert.com/drain05.htm#exmh

 

[jpread988]

cheers for the reply,

the link you provided states you cant enter at 90 to toe flow

would you still not suggest this?

by an elephants foot i mean one of these well something like this just found the img on a quick google search

 

[noseall]

Elephants foot?

What on earth is that!

 

[Newboy]

That's an internal manifold

Try one of these

http://www.screwfix.com/p/5-inlet-inspection-chamber-base/74362

and one of these

http://www.screwfix.com/p/87-5-double-socket-rest-bend/12719

 

[Hugh Jaleak]

The section of the link you have quoted seems to be concerned with rainwater drainage, which is fairness is not quite so critical as foul drainage as it is only really carrying water. They are also using the preformed plastic chambers which already have the connections on each side appropriately angled into direction of flow via the channels within the base.

Really need to check with the B.C.O. that such a connection would be permitted on the foul, and especially if you are breaking into an existing masonry chamber, the connection needs to be got right or you may be storing up problems for later on, once the new drain is in use. Trying to shove rods around a 90deg bend is nigh on impossible, any greater angle and it'll be time to call in someone with a jetter....

I have come across this type on connection in the past, but on several jobs where the drains were being relaid, wherever possible the connection was relaid and/or realigned to a better angle.

 

[Newboy]

Not quite sure why you believe that this is rainwater drainage - spec. is for either foul or rainwater.

 

[Hugh Jaleak]

Pic in link shows a connection to a linear channel, so rainwater.... Not saying it cant be used on a foul run, but still think it needs to be got exactly right or the OP will be storing up trouble for the future....

 

[Newboy]

Apologies - realise you mean the plan, thought you meant the chamber/rest bend