Question on foul drain / adding storm water drains

[pinenot]

Will look forward to seeing it...pinenot

 

[damanpunk]

Hi Pinenot,

Here's how I think the drains are all tying together, or at least this would make sense given the results of my hose pipe tests yesterday!! Where I've shown the pipe tying in (running underneath the house) could be anywhere between the drain pipe and the manhole cover.

Where the drain pipe enters on the North east corner it's seriously deep, I reckon it must be 1-1.5m easily. With that in mind I'm looking at an earlier option which I've detailed on the same attachment as I think I've easily got the depth to accommodate the additional pipe falls (at 1/80 it's 120mm fall or each pipe run). Not sure what to do in the way of gulleys, traps, access etc now that I know it's definitely a shared system.

 

[pinenot]

OK, lets summaries what we've got so far. The house is built on a slope, front to back, with the drain run wrapped around it' footprint, left - right, as per on your drawing. What I don't quite get yet is the direction of flow, but using my experience I can assume ~ the drain run starts (your property) at the existing mono pitched garage roof rain water downpipe. From this it flows to the NE corner of the building where it turns S 90 degree, along the E elevation to a manhole, from this it heads out to the main sewer in the street passing a rodding eye on it's way (the last connection? )

Are you simply wanting to replace an existing mono pitched, prefabricated concrete garage, with a purpose built twin pitched roof garage?? with sink connection (needs location on dwg) ...pinenot

 

[damanpunk]

Hi pinenot, I am a complete moron. I attached the link to the wrong picture!

This is the updated one which should make sense with the text

 

[damanpunk]

Also, I did these for my planning application which shows the site layout a bit better maybe

 

[pinenot]

Ok, phew...now I've got it, thanks.
Why not omit the SW downpipe, run the new rhone/gutter to the downpipe at the NW corner which you connecting to the drain run anyway? I don't see why you need two, am I missing something?

 

[damanpunk]

SW drainpipe is there because I was told I'd need it by the architect originally involved, apparently the rainwater calc needed the two as it's taking the surface area of the house roof and garage. Apparently one wasn't enough.

I'll dig out the formula and do my own calc tonight though, just incase it was wrong!

Now that you can get your head round the pipe runs would I need trapped gullies at each location on my new runs?

 

[pinenot]

You could fit a trapped gully with removable grate and rodding point, at the NW corner RW downpipe. A gully with grate is good for trapping leaves and with a removable rodding plug you could omit the one the one I previously suggested at the NE corner, giving you full rodding from the beginning of the drain run...pinenot

 

[damanpunk]

Thanks for that bud, appreciated!