djcdan Posted July 19, 2020 Share Posted July 19, 2020 Hi all. We sunk our septic tank last week, and based on manufacturers installation guide we surrounded in dry mix. We took level measurements prior to backfilling, but at some stage (possibly with weight of water and potentially a pocket beneath the septic) there has been movement during installation and the inlet end now sits 1.5cm lower than the outlet end... ? We need to find a way to rectify the situation before we begin using. A complete removal is a possibility, but one that I'd like to avoid to avoid the time and cost involved as well as the potential for puncturing the tank. If we could find a solution without uninstalling, that would be ideal. The best solution I can come up with is lowering the outlet point. The outlet point is a separately manufactured part secured to the HPDE tank with a form of sealant. My idea would involve removing the outlet (possibly with the correct sized hole saw), creating a lower hole (again with the hole saw) and then securing and sealing the joint with a suitable form of sealant. I would lower the outlet by around 5cm. Has anyone had similar issues before? Does my idea have legs or am I best exploring other options. Link to comment Share on other sites More sharing options...
PeterW Posted July 19, 2020 Share Posted July 19, 2020 Which model tank is it ..? Link to comment Share on other sites More sharing options...
djcdan Posted July 19, 2020 Author Share Posted July 19, 2020 Tricel Vento 3080 L. I'll attach a photo of the outlet - if that makes any difference. Link to comment Share on other sites More sharing options...
PeterW Posted July 19, 2020 Share Posted July 19, 2020 Ok so this may cause you an issue from the MIs Comes complete with an integrated outlet filter system for increased solids removal and soakaway protection, extending the life of the soakaway. I think you need to dig it out. Sorry. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 19, 2020 Share Posted July 19, 2020 1 minute ago, PeterW said: Ok so this may cause you an issue from the MIs Comes complete with an integrated outlet filter system for increased solids removal and soakaway protection, extending the life of the soakaway. I think you need to dig it out. Sorry. +1 Get a good operator to go around the lot, digging into the surrounding ground, and then wiggle the whole mass back into a correct position. Can be done in a day. You'll need a tonne or two of type 1 handy to back-fill. Hose that into place 300mm at a time to allow it to settle and compact. Link to comment Share on other sites More sharing options...
djcdan Posted July 19, 2020 Author Share Posted July 19, 2020 9 minutes ago, PeterW said: Ok so this may cause you an issue from the MIs Comes complete with an integrated outlet filter system for increased solids removal and soakaway protection, extending the life of the soakaway. I think you need to dig it out. Sorry. The outlet filter system is a cylindrical insert that fits inside the inspection chamber you can just about see in that photo. The outlet slots in to the insert. Imo, there should be no issue reintegrating the new outlet position to this insert if this adaptation is made to the tank. Link to comment Share on other sites More sharing options...
djcdan Posted July 19, 2020 Author Share Posted July 19, 2020 12 minutes ago, Nickfromwales said: digging into the surrounding ground, and then wiggle the whole mass back into a correct position Our subsoil is clay. Around 50% of the previously excavated hole was topsoil with clay beneath. There won't be much opportunity for wiggling in to the correct position. To get any of the clay moved beneath the dry mix to solve the issue it would need the entire mass lifted out. The mass will weigh 7T, so our groundworkers digger wouldn't cope with that. Link to comment Share on other sites More sharing options...
PeterW Posted July 19, 2020 Share Posted July 19, 2020 Ok so the inlet and outlet are 175/225 respectively on the tank according to the MIs You now have 175 and 160 - so basically you have a tank 65mm too high at one end so it’s close on 2 degrees out of level. Water doesn’t flow up hill .... This also means you have the potential for the weir and baffles internally not to work, so you have a non working septic tank. Irrespective of who is at fault or how hard it is going to be, I would take that out and start again. Looking at the waste filter system it is connected to the outlet internally - you can’t just hack a hole in the tank and expect it all to drop to a lower level. Link to comment Share on other sites More sharing options...
nod Posted July 19, 2020 Share Posted July 19, 2020 Your only option is to dig it out and start again A real pain but one of those things that just happens Link to comment Share on other sites More sharing options...
djcdan Posted July 19, 2020 Author Share Posted July 19, 2020 @PeterW @Nickfromwales Thanks guys. The bearers of the bad news I was hoping not to hear, but still expecting to hear. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 19, 2020 Share Posted July 19, 2020 1 minute ago, djcdan said: @PeterW @Nickfromwales Thanks guys. The bearers of the bad news I was hoping not to hear, but still expecting to hear. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 19, 2020 Share Posted July 19, 2020 If you start now, you can be finished by Wednesday teatime. ? Link to comment Share on other sites More sharing options...
djcdan Posted July 19, 2020 Author Share Posted July 19, 2020 4 minutes ago, Nickfromwales said: ? This image will give me nightmares tonight. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 19, 2020 Share Posted July 19, 2020 Sleep tight. Link to comment Share on other sites More sharing options...
Cpd Posted July 19, 2020 Share Posted July 19, 2020 (edited) . Edited July 19, 2020 by Cpd Link to comment Share on other sites More sharing options...
ToughButterCup Posted July 20, 2020 Share Posted July 20, 2020 13 hours ago, djcdan said: .... there has been movement during installation and the inlet end now sits 1.5cm lower than the outlet end... ? ... You have my genuinely deep sympathy. I used to have nightmares about this issue. If you are in Lancashire, I'll come and give you a hand sorting it out.... Link to comment Share on other sites More sharing options...
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