I've got a new combined foul & surface water connection to do in an existing manhole. ST approved and building control will be overseeing whole job but i'd like to get on and do it now before the rest of the works start on the job. Best to dig a trench through someones garden this time of year rather than height of summer.
I'm coming in at about 90deg to existing main channel.
Main channel is 6" and branches are 4".
My new branch will be 4" plaggy and 80:1 fall.
I've seen/had these done a few different ways before and want to see what consensus is here. Will be coming in at the same invert as other branches approx 3" up off main invert. I see this website says not to do stepped invert for foul but opposite branches are like that. I wouldn't want to create a level connection and have the other branches spewing into that. Perhaps this advice is intended for when there isn't such a good flow upstream in the main invert?
I'm reckoning I want to be pointing at 45deg where it runs into main invert
As i'm coming in at 90deg, I have loads of long rest 90's and these have a bit of a course finish outside. I thought I could cut back to anywhere around 45deg and shape the cut so the top of this bend is open right back to near wall of IC. Nice smooth curve for flow and bit of bend visible.
I see you can also now get a 22.5deg connection which has fine stone bonded to outside to help the benching. I considered using one of these with another 22.5deg on the back then running my pipe into this.
Finally i've seen them done with a stub of pipe and a 45deg on the back of this or again could go 2no. 22.5deg.
I prefer the first option as it uses one of my many long rest bends but thought i'd run it by this knowledgeable site. I don't think the inspector would have to strong an opinion either way, its just a choice of what fittings.
if you are coming in from the right hand side in the picture you need to get it so your slipper exits between the other 2 inlets
be careful not to break the main run,slippers seem hard to find now so I make my own by cutting a bend which you allude to
cheers LLL
Right hand side yeh. Think I might try to core drill through brickwork and keep pushing into benching but probably not as easy as it sounds in a trench. Perhaps chisel and cut away benching and edge of pipe.
Here's the ones I see of the shelf £35!!!
But i'll cut my own if it's the accepted norm.
Am i right about the stepped invert? Is the advice against it assuming you don't have decent flow behind on main run
you need the bottom of your slipper to touch the top edge of the invert of the 6 inch main, i always use 2:1 muck with SBR for benching
cheers LLL
ps use plugs to stop neighbour mr hankey appearing
Big of closure. Got the job done. Ended up cutting a long rest 90 for slipper.
The original work wasn't done that well to be fair. The 6" main run joints aren't too clever and the entries on the other side are a bit rough. Water pisses out middle of benching when front drain in use! Still it's done the job for a few years. Pipe was already a bit broken (bad joint) underneath where my slipper sat so I benched up underneath this too. Used sbr in mix. Not enough room to get 100mm of benching behind slipper. More like 50mm
Anyway good point of reference for people if my work is up to scratch!
Imagine a bco passing that forward connection on the other side nowadays. He'd tell you that everything would cling to that rough joint but years of use says otherwise eh!
