storm water issue

[gomer]

One for the plumbers or someone experienced in these areas.I also am trying to get this info elsewhere so I will also give feedback if I get any.Any assistance or ideas would be great thanks.

I have a storm water issue.I have a bird aviary I am building and have already laid all the foundation work. Unfortunately due to another downpipe issue I need to now run The storm water pipe through a agi drain pipe under a concrete slab being about 4 metres wide.The roof area I am going to build is 12m x 5m (this is the slab size so the actual roof sheets will be a little over 5m).If possible I plan to use 90 mm pipe to the agi drain then reduce to 75mm for about 4m then back to 90 mm.The agi drain will be about 2.3 m below gutter height so it will have a 2.1 to 2.2 m header ? height then run the 4 m under ground through the agi drain then back into the 90mm pipe again.The location for rainfull purposes is South Western Victoria.

[Tiaris]

Is the ag-pipe already under the slab?

[gomer]

Yes the ag pipe is already under the slab it runs under three brick foundations about 4 to 7 bricks deep.and comes out the end wall into a paddock lane way at natural ground level. A 90 mm pvc tube wont go up it.I think a 75 may do.I then will run it to a rain water tank.

[Tiaris]

Maybe if you sand the leading edge of the 75mm polypipe this may help it to squeeze through. The slots in the ag-pipe may give it some room for expansion if required too. Look like decent footings you have there. When will this affliction ever end?

[gomer]

Yes maybe but before I try I am trying to find out if what I propose doing will it move the water away quick enough still.I have yet to find anything on google .I sent a email of to the 75mm pipe manufacture tech guy but maynot get a reply for weeks as he is out of the office.I have a few other options I am thinking of.This one however is the easiest if it can handle the water and get it up the pipe.

[Tiaris]

The only issue I can think of is the potential slow down during the most torrential rain when the 90mm may be at or near capacity and the reduction to 75mm will cause a bottleneck with some backup of water. This should be very rare but is likely to be problematic at any time it does occur (if at all) depending on exactly what the situation is at roof level??

[gomer]

Yes I am thinking It will be ok but was after some advise from someone who knows all the tech stuff.If it was only a few times a year it couldn't handle it it could then just go into ground water and down the agi drain.

I cant get this to download to work it out.

http://www.roof-gutter-design.com.au/swpipe/swpipe.html

[finchbreeder]

Looks like a usefull program if it could be downloaded. Biggest consideration is the drop of the piping and that there is plenty of clearance or storage at the end for the water. But I am sure you know this. I know the theory being a plumbers daughter. But not the fine details sorry.
LML

[SamDavis]

Pretty small roof area for a 75mm would be my GUESS. I think the issue might be the 90 to 75mm join which is a likely place for leaves/crap to cause a blockage. Maybe install some sort of inspection screw-on doovy at that location so it can be cleared out should a problem occur.

If a read correctly, you'll try to insert a 75mm PVC pipe down a 90mm ag pipe. Surely the flexible ag pipe will be doing a bit of a wiggle under the slab which will make it impossible, or am I misunderstanding?.

[gomer]

No doubt it will be wiggling. That's why I was trying to work out if it is even worth trying. I was also thinking of flexible storm water pipe if it's available. May have to buy some 75 mm and try it next week. A leaf strainer at the gutter end would allow for any over flow and keep leaves out.