Browse Forums Landscape & Garden Design 1 May 23, 2010 3:09 pm We've recently moved into our house and really need to get the stormwater system done. But I'm having trouble finding guidelines for it. In our estate we have a stormwater system to connect to. My understanding of it (after scouring our councils design guidelines) is there is 90mm PVC pipe sticking out of the ground at the front of our house, that pipe along with our neighbours, is connected to a soakwell of sorts and that is then connected to a large pipe that goes to a central stormwater system. It seems to me that all I need to do is run stormwater pipe from each of my down pipes to the pipe out the front with a slight downward slope. A few things I'm uncertain of: I'm concerned about 90mm pipe not being enough in heavy downfall resulting in gutters overflowing, does this concern have merit? To overcome the above concern, I was going to put grates under the downpipes instead of connecting them directly, this way the grates overflow rather than the gutters. Also I thought I should possibly put a grate over the pipe that connects to the estate storm water system, seeing as this will be the point of most pressure in large downfalls. I would have a T piece with my storm water system coming in from the side, the pipe to the estate system from the bottom, and a grate at the top. I've also read that a slope of about 1cm/1m of storm water pipe is sufficient. Another detail, due to the design and positioning of my house, the stormwater pipe will have to start behind our garage on the left of the house and go to the backyard, across and down the right hand side and then across the front to the left hand side where the estate stormwater connection is. We have a zero lot wall on the left, so there is no alternative route. Any help is appreciated! My main concern right now is if the 90mm pipe is sufficient because I have access to a truck today so I can at least buy all the pipe and not need to cut it down to 3m lengths. Thanks Building with RedInk at Waterhall in WA, check out our blog: http://justinandashlyshouse.blogspot.com/ Re: Stormwater design considerations in WA 2May 23, 2010 3:35 pm Do you have to connect to the central stormwater ? May be easier to run half your downpipes to this and deal with the rest locally with your own soakwells. Yes, definately use a grate between downpipe and drainpipes, can't see why not at the central connection also. 90mm should be able to handle most events. The more downpipes you pick up the more water to deal with so maybe 90mm may be overloaded at the end but the central connection is 90mm anyway so you are stuck there. Perhaps connect into the central connection directly and have your grates at your downpipes otherwise you will have one big central flooding location whenever the flow gets too much. Re: Stormwater design considerations in WA 3May 23, 2010 6:27 pm I did consider soakwells, but our ground is a bit clayey so I'd rather avoid it. I guess the 90mm should cope with most rain fall and then on those few occasions a year when it's not enough it shouldn't be too much a problem to have a bit of overflow. If I put a grate over the estate storm water connection then at least if that over flows it'll just go onto the street and into the street storm water. Thanks for the suggestions Keen. Building with RedInk at Waterhall in WA, check out our blog: http://justinandashlyshouse.blogspot.com/ Re: Stormwater design considerations in WA 4May 26, 2010 8:58 pm Something else I've heard of is surrounding the storm water pipe with gravel to prevent fine sand entering. I'm going to use PVC pipe sealant on all connections so is this necessary? I'm not sure if there are other reasons for it's use. Building with RedInk at Waterhall in WA, check out our blog: http://justinandashlyshouse.blogspot.com/ Re: Stormwater design considerations in WA 5May 27, 2010 9:21 am If you glue your connections nothing will get in, it is a pretty good seal. Just make sure you compact well underneath your pipes before you bury them so they don't subside and crack. Also compact the backfill in 'lifts' of 0.5m or so, jogging up and down on the spot over the fill for a while is as good as any, or tamp down with the end of a 2m bit of 4x2. Gravel is normally used around soakwells to aid in drainage. Re: Stormwater design considerations in WA 6Aug 17, 2010 11:47 pm There is a stack of threads on this. I don't suggest directly connecting the downpipe to the soakwell. Otherwise when there is a down pour the water will backup the downpipe and flood your wall spaces and eves. 90mm has the same volume as the down pipe size so using 100mm won't change anything. I have posted some photos somewhere. Ideally you would engage a landscaper to give you some insight what they may need in the space to make your vision come to life… 1 13636 Plumbers 'can be' plumbers, made all the worse by self certification which the building surveyor invariably accepts as proof of compliance! The good thing is that you know know. 3 4859 Grab a hose, insert it at the top of the inlet/down pipe and turn the water on and see where the water is escaping from. Then you'll know. 3 8465 |