Browse Forums Building A New House Re: Metricon Merricks 42 Clarion - Melbourne 101Sep 25, 2020 12:18 pm Hi SaveH2O, I tried to reply a few times including images from our Council drainage plan but the tab keeps crashing. Anyway, it is specified that the detention slow-release outlet is 20 mm-diameter, and there is a top overflow of 100 mm-diameter. So the tanks have been installed according to the Council requirement. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ There are additionally 2 tanks on Lot 1 with 500L and 1250L of detention, respectively, also both specified with 20 mm-diameter slow-release detention outlet and 100 mm-diameter overflow. I could imagine in the event of sustained rainfall that if the incoming rate exceeds the outflow capacity that this could lead to tank overflow. The common property drainage leads to a 2x 600 mm-diameter orifice pit at the bottom of the property, so I am guessing that this should not overflow leading to water flowing back uphill. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Interested in your thoughts on that. Cheers, r_13 Re: Metricon Merricks 42 Clarion - Melbourne 102Sep 25, 2020 3:15 pm Unfortunately, council boffins who draw up these regulations often have no qualification or credible practical experience to do so as would appear to be the case here. This often results in unsatisfactory outcomes. The plumbing visible on your tank doesn't match the above diagram but I will comment as per the diagram and the council's requirements that should be in your contract. Rainwater harvesting regulations are poorly framed but the base line is that the water tank and its plumbing is part of the stormwater system and subject to the same regulations. I'll try to explain the basics the best I can so you can relate them to your situation. The roof drainage system has to be designed to handle your region's 1:20 year storm event without the gutters overflowing. If you are in the Melbourne region, your 1:20 year storm intensity will be about 130mm/hr, based on an average fall of 2.1666 mm per minute over a 5 minute rain intensity duration. 2.1666 x 60 = 129.996 mm/h. Your roof catchment area includes the gutter's perimeter but also a calculation to include upper storey walls that abut a lower roof area and collect additional water during wind driven rain but keeping it simple, your roof area (if you are in a 130mm/h 1:20 ARI will produce a minimum of X (roof area) x 2.1666 mm per minute as the minimum roof harvest during a minimum 1:20 ARI. If for example your roof area is 250 sq m, the amount of water discharging to the downpipes (not including abutting walls) would be 250 x 2.1666 = 542 litres per minute which will be discharging into a tank with a 20mm and a 100mm overflow orifice. The two water tank overflow pipes will also be meshed and mosquito proof metal mesh has little more than 50% open area. Fortunately, round threaded wire mesh has less flow restriction than flat mesh and so the bellmouthing effect isn't as restrictive as you may think when considering its % of open mesh area but it still presents a considerable restriction. AS/NZS 3500.1 Section 8 Water Storage Tanks shows that an unmeshed horizontal 100mm overflow pipe has a discharge rate of 4.67 litres per second (280.2 lpm) with the tank's water level 100mm above the pipe's invert (the bottom of the pipe). Unless the tank has the mesh replaced with either a flap valve or a meshed air gap, your 100mm overflow pipe will not discharge at 280 lpm...but 210-220 lpm maybe. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Your tank has a 4,000 L detention compartment that serves as mitigation during high rain intensity but the roof area will quickly fill the detention compartment and the 100mm overflow clearly is inadequate. It must also be remembered that the (unmeshed) discharge rate that I have quoted is with 100mm of water above the invert whereas the unmeshed discharge rates with water 30mm and 75mm above the invert are only 0.53 and 2.78 lps respectively. To alleviate any concerns, the easiest way is to fit a second lower 100mm overflow and have the two overflow pipes converge to a 45 degree junction. A second (unmeshed) lower horizontal overflow with 150mm of water above the invert will discharge at 6.6 lps (396 lpm). Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ If the installers/plumbers have plumbed an overflow system that is different to the contract's diagram, just post some photos for an opinion if you like. *It is very important that the 20mm overflow's mesh is accessible for cleaning as these often gum up. I hope that this helps. 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: Metricon Merricks 42 Clarion - Melbourne 103Sep 26, 2020 12:31 am Thanks so much for your time and this detailed information SaveH2O Indeed the tank has been fitted with a single 100 mm out flow pipe connecting both exits. The plumber did not install the junction piece with inspection port at the level of the detention slow release exit, which I need to address. The piece is there, supplied, but the plumber used his own pipes and put a different 100 mm T junction instead. He is coming back to fix a few other issues soon and I'll mention it. Cheers, r_13 Re: Metricon Merricks 42 Clarion - Melbourne 104Sep 26, 2020 7:02 am Going by the photo of your unplumbed tank, I am wondering whether they have plumbed it like in the photo below? This shows a system that interconnects (loops) the infeed pipe with an overflow pipe inside the tank. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 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: Metricon Merricks 42 Clarion - Melbourne 105Sep 26, 2020 7:28 am SaveH2O Going by the photo of your unplumbed tank, I am wondering whether they have plumbed it like in the photo below? No, it's a single pipe. First it was installed crooked like this below. The tank was also hanging off the edge of it's slab. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Since then we have rectified that to be straightened however in practice there is no functional difference to the photo shown. Re: Metricon Merricks 42 Clarion - Melbourne 106Sep 27, 2020 9:37 am That is, there is a single 100 mm-diameter pipe from overflow which intersects to the detention slow-release opening. The detention slow-release opening is actually 100 mm-diameter and is supposed to have a plate with a 20 mm-diameter hole installed. However this was done without an inspection port for the detention plate, using the plumbers own parts. (I still have the 4-way T-junction with observation port and the detention plate in the house along with the yet-to-be-installed pump.) Re: Metricon Merricks 42 Clarion - Melbourne 107Sep 27, 2020 11:28 am r_13 (I still have the 4-way T-junction with observation port and the detention plate in the house along with the yet-to-be-installed pump.) So basically it means that the Council's Permissable Site Discharge (PSD) requirement through a meshed 20mm outlet may not have been complied with and the current detention outlet could even be a full 100mm opening. Unfortunately, such things are common because plumbers have no training in rainwater harvesting, the reason that practically every rainwater harvesting system that I see on Homeone is either sub standard, not compliant or both. There are rarely just one or two issues. Overflow outlets have to be meshed and best practice has the top overflow outlet's mesh accessible from above for cleaning. You need to make sure that this is achievable with your tank. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re pump, incorrectly plumbing the pump will shorten it's life and/or deliver the worst water in the tank. Common mistakes are... Fitting a 90 degree elbow directly to the pump's suction side. The pump's suction (inlet) hose should respect a straight length of preferably 8 (internal) diameters immediately before the pump. Fitting an external pump to the tank's drain valve (that is fitted right at the bottom of the tank). Fitting a submersible pump (that draws water from the bottom) directly on the tank's floor where they spend their life vacuuming the nearby sediment. Such pumps need to be on a platform above the sediment layer but note that not all submersible pumps draw water from the bottom. Water settled on the bottom of the tank is also the water with the highest density...the worst quality water. The tank's pump supply valve needs to be above the anaerobic zone if drawing good quality water is important. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 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: Metricon Merricks 42 Clarion - Melbourne 109Sep 27, 2020 2:55 pm Just be aware that sub standard practices are often still compliant due to the lax rainwater harvesting regulations but some will void the manufacturer's warranty. Unfortunately, manufacturer's installation recommendations are no longer recognised by the NCC. 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: Metricon Merricks 42 Clarion - Melbourne 110Sep 28, 2020 8:52 am SaveH2O Re pump, incorrectly plumbing the pump will shorten it's life and/or deliver the worst water in the tank. Common mistakes are... Perhaps it's worth mentioning that this tank will supply only the toilet cisterns, and garden watering taps. However in any case the current installation appears as follows: Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Metricon Merricks 42 Clarion - Melbourne 112Sep 28, 2020 11:14 am Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ There is no top entry that allows access to the overflow mesh. The pump is connected to a drain valve that will draw dirty water to the cistern but the pump does have a pre filter. It is a good pump. Rainwater is naturally acidic and reacts with copper pipe. None of the issues (apart from the inadequate overflow capacity) are non compliant but best practice is lacking. 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: Metricon Merricks 42 Clarion - Melbourne 114Oct 06, 2020 5:14 am Last installment paid. Check. Home insurance organised. Check. Getting handover today... maybe!? This week for sure... Landscaping ongoing, concrete driveway scheduled for 12th Oct. Rental notice given, moving date set 22nd Oct, it's all happening. Re: Metricon Merricks 42 Clarion - Melbourne 115Oct 06, 2020 6:59 am r_13 Last installment paid. Check. Home insurance organised. Check. Getting handover today... maybe!? This week for sure... Landscaping ongoing, concrete driveway scheduled for 12th Oct. Rental notice given, moving date set 22nd Oct, it's all happening. Good luck r_13! Such an exciting time!! Enjoy the ride 😁 Re: Metricon Merricks 42 Clarion - Melbourne 116Oct 06, 2020 1:32 pm r_13 Last installment paid. Check. Home insurance organised. Check. Getting handover today... maybe!? This week for sure... Landscaping ongoing, concrete driveway scheduled for 12th Oct. Rental notice given, moving date set 22nd Oct, it's all happening. Oohhh how exciting! Now the really fun part starts. Very interested in your driveway. Exposed agg? I wanna see! https://thomasarcherbuild.blogspot.com/p/blog-page.html - Thomas Archer Homes - Custom Nouveau 41 Re: Metricon Merricks 42 Clarion - Melbourne 118Oct 07, 2020 11:06 am Blacktea2sugars Very interested in your driveway. Exposed agg? I wanna see! Yes, we have decided to go for exposed aggregate in a dark colour, with matching colour in our semipermeable sections. Since we are building on a battleaxe block, the driveway is long - it will take about 240 m² including 60 m² of semipermeable... The preparation earthworks are happening now, boxing Monday, pouring hopefully on Tuesday! Re: Metricon Merricks 42 Clarion - Melbourne 119Oct 07, 2020 11:39 am Congratulations! Such a great feeling to finally get in your house isn’t it?? (Even if the hand soap is absolutely terrible!!) 😃😃 Re: Metricon Merricks 42 Clarion - Melbourne 120Oct 16, 2020 12:09 pm blacktea2sugars As we are at the "concrete and driveway" stage, I too am shocked at the cost. Our gagrage is really wide, and quite far back (no where near your 40 m tho!) Who knew concrete is so expensive!!! Yes, it is expensive but ... it looks sooo goood... Our driveway is being mostly poured today, then it should set before we move in next week. Then the remaining semipermeable parts of the driveway will be done next Friday! Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Hi, First of all, thank you to this community for sharing your thoughts and opinions. We are in early days of our pre-contract stage for Metricon Doulton and we are… 0 11870 Hello All 🙂 We are planning to start our journey of construction our first home. 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