Browse Forums General Discussion Re: On Site Detention - Charged Line? 2Jan 21, 2019 7:39 pm 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: On Site Detention - Charged Line? 3Jan 21, 2019 10:21 pm Thanks SaveH2O, I was hoping you might respond to my post. The tank manufacturer is Kingspan and that diagram is from their brochure. It should be fairly easy to get the pump raised. My builder is Rawson and from what I've seen of their installations the inlet piping will be more like this... Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ The hydraulic plan is at the preliminary stage and I'm being told that the tanks have to go on the opposite side of the house to what we wanted "because I need to drain the outlet/overflow somehow to the street via gravity fall (Can not achieve that on eastern side due to levels - I can not hide the outlet/overflow on eastern side with raised garden bed, due to overland flows in front of the property)". That's not very clear so I checked with the hydraulic engineer what that meant and he confirmed it meant the OSD couldn't drain via a charged line "because it wouldn't work". When I pressed him about why he said he couldn't explain it to me. We have a strong preference for the tanks being on the other side, but I would accept what he was saying if it was against a code, standard or Council guidelines, but that is not what he said. I'm getting a little tired of being treated like an idiot because someone just wants to do what's easiest for them. We're paying a lot of money to build this house, you'd think what we preferred would matter a little more... The hydraulic plan is below. It's not hard to get the invert of the OSD nozzle at an equivalent height in my preferred location simply by choosing a taller tank (or using a tank stand). The difference is that the OSD and overflow line will slope uphill (is charged) to the final control pit. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: On Site Detention - Charged Line? 4Jan 26, 2019 10:10 pm Have finally found the time to get back to this. Sorry for the delay. Installers should know how to read instructions and install pumps correctly. Unfortunately, many pumps, both submersible and external, are poorly installed. I'll touch on the tank's glaring installation faults before getting to the hydraulics. Hopefully, you and others who read this will be able to avoid the all too common mistakes of unknowledgeable installers. I will make the water tank installation issues a separate post. Most new home owners have sub standard installations like in the photo you linked. DESIGNER'S SPIEL The photo shows two slimline watertanks supplied by wet (charged) systems that divert water from the downpipes to the tanks. Even the downpipe at the rear of the tanks is not plumbed to divert water to the top meshed inlet on one tank. Both tanks have vertical risers that transfer water from what would probably be separate wet system pipes to the tank's top meshed inlets. The end of the upper discharge pipe communicates with the tanks top inlet mesh at 90 degrees. The large caps near the bottom of the vertical risers are Inspection Openings (IOs) fitted to flush the wet systems of crud. The two short pipes that branch downwards from near the top of both vertical risers are First Flush Diverters which are used to capture the dirtiest water off the roof when it starts raining and are fitted to improve the quality of the water entering the tank. The small black tubes you see connected to the bottom of the First Flush Diverters divert water from drippers fitted to the bottom of the First Flush Diverter to the overflow pipe on the tank on the left. At the bottom of both tanks and partially obscured by the left tank's vertical riser is a curved pipe. This pipe is a balance pipe that equalises the water levels between the two tanks.Because the water level will equalise to the level of the left tank's detention overflow, both tanks are effectively detention tanks. Only the left tank has an overflow pipe fitted and there is an IO fitted at mid height. This is to allow access to clean the mesh covering the reduced size detention orifice plate that drains to the overflow pipe. There is also a drain valve fitted to the bottom of the left tank. There is no indication as to the type of pump to be installed. It is impossible to know whether good leaf diverters have been fitted to each downpipe but they rarely are. The photo shows a typical installation that are seen time and time again on Homeone threads and elsewhere.....so, why is it sub standard? NOTE: Sub Standard does not always signify non compliance, most sub standard installs are still compliant! Here's why! Unless drained, wet systems retain water and these two tanks will retain water to the First Flush Diverters invert levels. Leaf diverters are compulsory fittings to wet systems in most northern areas to prevent mosquitoes from accessing the water in downpipes but they should be compulsory on all wet systems. From egg to adult takes 12 days, + or - a day or two and each 'raft' can have up to 400 eggs. Leaf diverters also prevent debris being diverted into the wet system where it can build up and sometimes turn the water stagnant. The best leaf diverter currently available is the ICON Leaf and Debris Controller, sold in Bunnings. The Inspection Outlets will only drain the wet system to the outlet's opening and the driving force (head pressure) is only provided by by the water retained in the downpipes at the height between the bottom of the first flush invert near the top of the riser and the bottom of the IO cap near the bottom of the riser, a distance of approximately 1.5 metres. Thes equates to approximately 9 litres in each downpipe. This amount of water is insufficient to properly flush long underground wet system pipes. The inspection cap on the tank at the right will also discharge next to the house foundation. EDIT: Note that water in a vertical riser does not conribute to flushing an underground wet system pipe due to the riser simply discharging through the IO but if a wet system pipe drains into a pit at the pipe's lowest point, the water in the vertical riser would then contribute a little to the initial pressurised flushing. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ The above diagram can be found at http://www.yourhome.gov.au/water/rainwater Note the first flush diverter fitted to the top of the vertical riser. The unmeshed discharge end of the vertical risers above the tanks top meshed inlets allow mosquitoes and other pests access. For best practice, the pipes should be lower at the top, plumbed with a slight dip and fitted with flap valves. See photos below. The tanks top meshed inlets should also be easily removed whenever necessary but discharge pipes communicating with meshed inlets at 90 degrees often make this task difficult. Whether this would apply to the tanks in the builder's photo cannot be determined. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ The First Flush Diverters fitted to the top of the vertical risers are a useless waste of money and water...but why? The answer is simple! When it rains, the first flush enters the downpipes at the other end of the wet systems while the first flush diverters fill with the settled water in the vertical riser!!! Rather than waste money, leaf diverters should have been fitted. The first flush drippers are simply a hole drilled in a washer and water drains out under pressure, losses of 4-6 litres per hour are common which is an unnecessary yield loss given that first flush diverters fitted at the wrong end of a wet system capture NO first flush. The pipes appear to be 90mm stormwater pipe which have an internal diameter of 86.2mm which gives a volume of 5.8 litres per meter. The first flush pipes appear to be about one metre long but the diverters also have a sealing ball inside which reduces volume, giving the diverters shown a volume of about 5 litres. Even if the first flush from just one downpipe was able to magically find its way through the water in the wet system and fill the diverter, how much rain would have washed the roof? Well, if that one downpipe drained 40 square metres of roof, the 5 litres of 'magic' first flush would equate to 0.125mm of rain! Would that really wash a roof? Of course not! It's all academic anyway because there are several downpipes plus all of the water in the wet system. The curved balance pipe at the bottom of the tanks is fitted too low, it should be above the sediment layer so that the inflow will dissipate better and not resuspend sediment. The very low drain valve fitted to the tank on the left is so called because it will drain water from the tank's anaerobic zone, the worst quality water in the tank. I just hope that it isn't intended to supply an external pump, something that I commonly see. If it will supply a pump, the water coming from more than one downpipe will be dropping at height to the immediate area where the valve is fitted. This and the turbidity generated by the very low balance pipe discharging into the left tank will do the water quality drawn by the pump no favours. 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: On Site Detention - Charged Line? 5Jan 27, 2019 9:28 am robw17 The hydraulic plan is at the preliminary stage and I'm being told that the tanks have to go on the opposite side of the house to what we wanted "because I need to drain the outlet/overflow somehow to the street via gravity fall (Can not achieve that on eastern side due to levels - I can not hide the outlet/overflow on eastern side with raised garden bed, due to overland flows in front of the property)". That's not very clear so I checked with the hydraulic engineer what that meant and he confirmed it meant the OSD couldn't drain via a charged line "because it wouldn't work". When I pressed him about why he said he couldn't explain it to me. I take it that all downpipes are diverted to the tanks. Aha, you have a control pit but it still doesn't make sense to me as to why a charged pipe with the correct minimum elevation at the tank's detention overflow cannot connect to the control pit from your preferred east side. What mitigation capacity does the control pit have and do you know your Permissible Site Discharge (PSD)? Discharge control pit – this is located at the lowest point on the site. All flows leave the site through this pit. The pit contains an orifice in a stainless steel plate fixed to the side wall. The orifice is sized to limit the discharge of water from the site to the maximum permissible rate. As you have stated, if there is positive head from the tank's detention outlet, it would drain charged. For a hydraulic engineer to say that he couldn't explain to you something that is so basic is just extraordinary. Re draining the tanks straight to the kerb, the site has a maximum Permissible Discharge Rate which includes any surface water as well as the stormwater. This is why you cannot have two separate pipes draining to the kerb. 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: On Site Detention - Charged Line? 6Nov 09, 2019 12:26 pm Hi Rob, how is your build going? We are building in Oatley and have run into problems with our stormwater. In the end, what stormwater plan did you go with and was it approved by Council? Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19515 4 10821 Hi everyone, Looking for some advise. We are about to build an above ground pool in our backyard. There is a private sewer line running under the pool at 1.6m… 0 11757 |