Browse Forums General Discussion 1 Jul 21, 2021 8:46 pm I’m building a shed and the gutters are only 800mm higher than the street gutter level and about 47 meters from the down pipe to the road. My question is will the water flow from the gutter alright or will it just fill the rest of the pipe and overflow the shed gutters? Re: Charged stormwater help!! 2Jul 21, 2021 9:45 pm You haven't provided any of the required information to provide an answer. For starters: Roof area. Regional 1:20 ARI. Pipe size. How many elbows, tees etc in the pipeline. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Charged stormwater help!! 3Jul 22, 2021 1:48 am SaveH2O You haven't provided any of the required information to provide an answer. For starters: Roof area. Regional 1:20 ARI. Pipe size. How many elbows, tees etc in the pipeline. 134 square roof area not sure about ari was going to have 4 100mm Polly down pipes so 2 elbows and 3 ts or y junctions and probably 2 45 degrees to get to street height Re: Charged stormwater help!! 4Jul 22, 2021 7:01 am Thanks. What area are you in? If I know that, I will be able to check your 1:20 ARI rain intensity. I also need to know the sub surface pipe size, I am assuming you are in a high intensity rain area given that you have mentioned 4 x "100mm Polly down pipes" (I also assume these will be 100mm pvc DWV pipes) which means that each downpipe is only draining an average 33.5 sq m. With an uphill slope, you should also look at having a flush valve at the lowest point to flush the pipe of sludge every now and then but rather than allow sludge to build up all along the pipe, fitting a simple DIY sediment trap I designed to a non turbulent section of pipe would capture bed load that would be flushed at a high scouring velocity through a smaller flush pipe. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ We use a 100mm x 40mm invert taper rather than the pipe reducer these days. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Charged stormwater help!! 5Jul 22, 2021 7:21 am SaveH2O Thanks. What area are you in? If I know that, I will be able to check your 1:20 ARI rain intensity. I also need to know the sub surface pipe size, I am assuming you are in a high intensity rain area given that you have mentioned 4 x "100mm Polly down pipes" (I also assume these will be 100mm pvc DWV pipes) which means that each downpipe is only draining an average 33.5 sq m. With an uphill slope, you should also look at having a flush valve at the lowest point to flush the pipe of sludge every now and then but rather than allow sludge to build up all along the pipe, fitting a simple DIY sediment trap I designed to a non turbulent section of pipe would capture bed load that would be flushed at a high scouring velocity through a smaller flush pipe. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ We use a 100mm x 40mm invert taper rather than the pipe reducer these days. Wow you are so helpful I’m glad I found this page 😃 I live in Armidale Nsw I’m not 100% sure what a sub surface pipe is however I was going to run the 100mm for everything all the way to the street and into a 90mm gutter adapter thing you cement in if that helps Re: Charged stormwater help!! 6Jul 22, 2021 12:42 pm That's great. A sub surface pipe is a buried carrier pipe. You can also buy 5, 15 and 30 degree 100mm DWV elbows. Irrigation shops are usually much cheaper than the big green shed when buying PVC pipe and fittings. I also recommend using the green (pressure) solvent cement (plus primer) with any charged system. DWV tees are well designed for drainage as the fittings communicate at an albeit small angle with the water in the carrier pipe plus the velocity from the downpipes won't be all that great anyway. Your 1:20 Average Recurrence Interval is most probably 160 mm/hr. This is based on an average rainfall intensity of 2.666 mm of rain per minute over a 5 minute duration. It is best to factor in a safety margin when using ARI figures when planning site drainage as they are the minimum qualifying requirement for each ARI classification. 134 (sq m) x 2.666 (mm/min) = 357 lpm. The 100mm SN6 DWV pipe has 3mm thick walls and an internal diameter of 104mm. This gives a volume per metre of 8.5 L. With a velocity of 1 metre per sec, the flow rate is 510 lpm. Looking good so far! The 90mm reducer at the end will add to the friction loss but not by a lot over its short distance. The pipe fittings also create turbulence which adds to friction losses which are expressed as equivalent pipe lengths. The 47 m distance is also thought of as friction loss when doing calculations. The downpipe closest to the junction with the 47 m pipe will have the greatest influence on flow rates, just think of the downpipes as water towers along a pipe system and their purpose. The Hazen-Williams formula is used to calculate flow rates in gravity fed pipe systems. Even if you were to have 100 m of total friction loss (you are unlikely to with an uncomplicated flow path but it could/will be close), you would still have a maximum velocity of 0.942 m/s which is 480 lpm with 0.8 m head. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 15473 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 3241 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 6343 |