Browse Forums Building Standards; Getting It Right! 1 Mar 10, 2016 7:40 pm Hi everyone, My house is almost at handover (haven't yet had PCI so I'm arming myself with ammo) but I have serious issues with my Stormwater and the job that's been done. My block is downslope to the street, so my Stormwater legal point is discharge is the low point of the property (I have a creek/water course running through). About a month after I signed my contracts I received drawings from the civil engineer of the Stormwater system, which included about 6 grated inlets, 3 drainage silt pits all evacuating to the low point of the block, with a wet charged system of 6 downpipes leading to my water tank (and a 13,000L tank with 10,000L storage and 3,000L detention with an orifice plate) This also formed part of my permits as the council required a detention system leaking at a slow rate to stop the neighbours down stream from flooding (with a 100mm overflow once the system was full) Anyway, I went out yesterday and noticed that all I received was 3 grated inlets, and a ring around half my house of what i assume is aggi pipe/slotted pipe, I can't tell as there's pipe bedding rock in the trenches (dirt not placed back over). I assume this will be sufficient provided the slotted pipe doesn't clog up, and at least the silt pits act as inspection points if it does clog up. The wet charge system though was connected wrong. Firstly, the engineering showed that I had leaf eaters/strainers at all downpipes, I didn't receive this, they're directly connected with no filter. Although I thought this might be a mosquito risk, I let it slide as I expected the strainer on the top of the water tank to act as a filter, but unfortunately, the plumber connected the Stormwater in pipe to the top outlet (what was supposed to be the overflow) and connected the out pipe (which discharges to the creek) to the outlet that is supposed to incorporate the orifice plate (the plumber didn't install it). It meant the detention system didn't actually detain or leak at a controlled rate, and that 3000L was effectively wasted space in the tank. I complained to the SS who said they would fix it. I went out today to find that they have now connected the in pipe to the top where the tank strainer is, but it's so tight against the strainer that I can't take the strainer out to clean the leaves, it's basically locked in. Also, there is only one outlet, although now connected at the top outlet of the tank (unrestricted), the 10,000L mark outlet which is supposed to be an orifice plate, is now unused, they've just sealed it up. I also realise there are NO inspection points anywhere along the wet charge system, it's entirely sealed. I have a few questions: 1. Is there an Australian standard or regulation that says inspection points have to be located in a wet charge system, and at what intervals? I have none. 2. Is there a standard or regulation that says my wet charge system must be sufficiently screened to stop rodents and leaves and mosquitoes getting into it? It's not drinking water. (I'm located in VIC) 3. Even though the civil engineering was drawn after I signed contracts, and the contract doesn't state individual components of the Stormwater (just a charge for a 'Stormwater system including agricultural drains and wet charge system to tank'), am I entitled to tell the builder to follow his own engineering? I've attached Photos: Thanks! Re: Stormwater and charged line system? 2Mar 11, 2016 2:34 am What is your roof area and do you know your 1:20 Average Recurrence Interval? If not, what part of Victoria are you in? BTW, "in pipe" is the infeed and the "out pipe" is the overflow pipe. As you already know, your stormwater /detention tank system is flawed, nor does it comply with your council's detention tank requirement. Do you know what your Permissible Site Discharge (PSD) is? It is not shown on the drawings. The way the infeed and overflow pipes were first plumbed and how they have now been 'rectified' is beyond incompetence. Apart from having no understanding of some very basic principles, the 'plumber' has obviously also not looked at the drawings. And who was the bright spark who optioned a detention tank with two 100mm overflows and with one above the other? The top of the wet system vertical riser need to be higher for obvious reasons and for best practice, the end of the pipe should be fitted with a flap valve to prevent mosquito and other pest ingress. Your post's second photo indicates that there is a lot of available head for a 100mm DWV wet system but I would like to run some figures once I know your roof area and 1:20 ARI. I assume that your downpipes are all 100mm but do you know your gutter's cross sectional area? If you know what the gutter is, I can look up its cross sectional area. Are they slotted? Can you also calculate the distance between the top of the tank (it looks flat) and the gutter's sole? I would like to know whether the leaf diverters were not fitted due to a possible lack of required hydraulic head if they had been fitted. The top overflow pipe also has little space between the pipe's invert and the height at which the tank would overtop during a 1:20 ARI. If I know your roof area, the 1:20 ARI and the size (internal diameter) of the lower overflow outlet, I can determine whether the tank's total overflow capacity will exceed the inflow capacity during a 1:20 ARI. This however should have already been done by a hydraulic engineer, have you seen the figures? I would also like to know whether the hydraulic engineer made allowance for the overflow mesh restriction. You have probably also noted that the drawing requires a 100mm mitigation capacity between the top of the overflow pipe and the bottom of the lowest section of the riser above the tank but this is impossible with the higher overflow pipe fitted so high. The roof section of the tank drawn is also not representative of the tank supplied. The smaller lower overflow outlet ideally should not be fitted with mesh because this can gum up and cleaning a low outlet's mesh is often very difficult to do. The best way to design and plumb the lower overflow is to have it fitted with a flap valve and discharging into a larger wye entry to the vertical downpipe. It has me beat as to why they didn't fit a smaller detention overflow outlet, that would have been more logical and it probably wouldn't have confused the plumber lol. The photo below shows a neat detention tank twin overflow, note the smaller bottom overflow outlet. tsch993 1. Is there an Australian standard or regulation that says inspection points have to be located in a wet charge system, and at what intervals? I have none. There is no requirement but some councils do have requirements. Check with council. The ones shown in the drawing would be substandard if installed because the wet system would not completely drain and there is limited hydraulic head. To flush and drain a wet system, the drain outlet should be via a tee fitted to the bottom of the vertical riser. A (often smaller) pipe then comes off that tee and runs to a point where it flushes. For best results, a DIY sediment trap that uses off the shelf parts should be fitted in a non turbulent section of the wet system's horizontal pipe to capture bed load. tsch993 2. Is there a standard or regulation that says my wet charge system must be sufficiently screened to stop rodents and leaves and mosquitoes getting into it? It's not drinking water. (I'm located in VIC) No mandated regulations but there should be! Most councils north of Sydney do mandate that wet systems are screened with leaf diverters and flap valves. tsch993 3. Even though the civil engineering was drawn after I signed contracts, and the contract doesn't state individual components of the Stormwater (just a charge for a 'Stormwater system including agricultural drains and wet charge system to tank'), am I entitled to tell the builder to follow his own engineering? I'll leave this to others with the appropriate knowledge to answer. I personally wouldn't be insisting on the IOs as drawn. Leaf diverters would be installed on a wet system by anyone with a social conscience given the trees that the photos show you have around you. 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: Stormwater and charged line system? 3Mar 11, 2016 9:06 am Thanks for the info! I'm unsure of my ARI but the postcode is 3159 My roof area covered is 154m2 according to my contracts. Regarding the 2x 100mm overflows, this is how I optioned the tank as per the council permit (which stated the lower outlet at the 10,000L mark was supposed to be a 35mm orifice plate to permit a discharge of no more than 2.4L/s) I've attached the relevant permit info that the council gave me. I'm unsure of the heigh difference between the gutters and the top of the riser in flow pipe, but it's over 30cm. I'd say it was cost cutting, not because they had insufficient room to install leaf traps. Re: Stormwater and charged line system? 4Mar 11, 2016 12:19 pm Your area would be in a 140mm/hr zone. The Ari is stated as mm/hr but this is based on an average rain intensity over a 5 minute duration, yours is 2.33 mm/min for 5 minutes. Your roof area will therefore harvest approximately 360 lpm during a 1:20 ARI, well within the flow capacity of a 100mm DWV pipe for your situation. There was no reason to fit the inflow pipe so close to the mesh. If you put some round shadecloth on the infeed inlet's mesh, it will make it a lot easier for you to clean the mesh. There are commercial products also available that fit over the mesh and lift out to clean. The SN6 pipe which you are almost certain to have has an actual internal diameter of 104mm, giving a volume of 8.5 litres per metre. The maximum discharge through a 35mm diameter round orifice plate on your tank will not attain 2.4 lps (144 lpm) as I judge the height above the invert to the top of the tank to be approximately 600mm but it may attain 1.9 lps. This is not allowing for an additional flow restriction caused by the mesh. The top 100mm overflow pipe however has sufficient capacity to handle the inflow capacity should the tank fill during high intensity rainfall. I would definitely be fitting leaf diverters to the downpipes. 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: Stormwater and charged line system? 5Mar 11, 2016 12:43 pm SaveH2O - if I recall right you were developing a new leaf diverter - how has that been going? Re: Stormwater and charged line system? 6Mar 11, 2016 7:17 pm I'll speak to the builder about fitting leaf diverters (particularly considering it's on the engineering) I also want them to fix the in feed (raise it higher) and if so I'll connect a mosquito flap. Also need him to get the plumber to properly connect the orofice plate outlet and make sure they actually put in the 35mm as required by the council. In one of the above photos, you have a picture of the in feed over the tank being braced against it, is this something I can buy or have they just created it themselves? Because the in feed is really wobbly at the moment. Thanks Re: Stormwater and charged line system? 7Mar 12, 2016 12:41 am tsch993 In one of the above photos, you have a picture of the in feed over the tank being braced against it, is this something I can buy or have they just created it themselves? Because the in feed is really wobbly at the moment. There are different ones available, they really should be used on all vertical riser. Plumbing supplies have them, they are usually called downpipe spacer brackets and sometimes downpipe spacer clips. Probably a couple of other names as well. 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: Stormwater and charged line system? 8Mar 16, 2016 9:39 am really sad to see that the client have to raised all these issues. What happens if you are not technical at all and just accepted their work? I really feel for those ppl that doesnt know until there is a massive pour down and found out the system is flawed. Re: Stormwater and charged line system? 9Mar 16, 2016 10:44 am Yep, welcome to the building industry where incompetent tradies and others when they get pulled up on something will try and dazzle you with science or blind you with bull$hit all because they took the easiest ( read cheapest ) route. Stewie Re: Stormwater and charged line system? 10Mar 16, 2016 1:56 pm Yes agree. Once they get paid they are outta there.... even if you try to sue them the process will take longer enough for you to rescind. I heard other builders creates a company for each build then close it after so they cant be sue!!!! scary stuff they dont care about reputation Re: Stormwater and charged line system? 11Mar 16, 2016 2:09 pm zc12345 really sad to see that the client have to raised all these issues. I see very few water tank installations that are not substandard. Compliance does not guarantee that the system won't be severely faulted. 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: Stormwater and charged line system? 12Mar 16, 2016 2:22 pm oneJohn SaveH2O - if I recall right you were developing a new leaf diverter - how has that been going? It is on hold. The 500 micron hard surface filter I developed is terrific but the unit needs an accumulator to slow the flow of water and height and debris passage clearances then becomes an issue. The only comparable similar unit is the 3P Rainus but it is 505mm tall and my first one using conventional methods was 492mm tall. I have reduced that by slightly more than half by using a few tricks but I still need to take off a few more mm without compromising the clearances. I am overseas right now but I will add more after I get back next week. 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: Stormwater and charged line system? 13Mar 16, 2016 3:48 pm SaveH2O I see very few water tank installations that are not substandard. Compliance does not guarantee that the system won't be severely faulted. Wow, what a shining beacon of success this first world democracy is, so often touted as the most desirable place to live in the world due to its "high" standard of living. Australia - leading the way again. sarcasm /off Re: Stormwater and charged line system? 15Mar 25, 2016 12:03 am The pressure on a column of water is only 9.82 kPa per metre, nothing to worry about. It looks like the plumber has actually used primer as required, ironic really. 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: Stormwater and charged line system? 16Mar 26, 2016 7:15 am SaveH2O The pressure on a column of water is only 9.82 kPa per metre, nothing to worry about. It looks like the plumber has actually used primer as required, ironic really. Yes primer is a good sign Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19497 Building Standards; Getting It Right! Thank you for the generous offer. I need to get the plumber out to give me an explanation. As mentioned I haven't seen any rain water discharge from pipes 1& 3. It… 7 10805 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 8451 |