Septic tanks. Plastic? Powered?

[AGT]

Maybe worth checking with the EPA/SEPA

We have septic tanks on sites I manage, and when we upgraded they insisted on a treatment plant.
Tighter guidelines I imagine

[Moxi]

LOL

I used to work with a company who manufacture GRP pump stations from 1.2m diameter all the way up to 2.4m diameter with depths from 1.5 to 6m deep. Every so often we would get a contractor who hadn't read the installation instructions and had either floated the tank in the cement or they overfilled the water in the GRP liner and split it as it had insufficient support from the mass concrete surround being poured. They were often very upset to be told it was their error and their cost. the correct way (for the liners at least) was to maintain 1 meter differential head of water above poured concrete level until the tank was filled, at which point the remaining concrete pour would not result in floatation.

Better than that though I once inspected a waste water treatment works down on the Isle of dogs (i think) right on the coast and only just above sea level. We were walking around the PST's (primary settlement tanks) these were 30 meter diameter 6 meter deep concrete structures on piles and they had concrete access paths doweled in to the outside of the walls at 1.6m from the wall coping. As designed these access paths should have been at the site ground level but due to an unfortunate incident the paths were all around 2,5 meters in the air and had to have earth backfilled under them and sloped at 45 degrees, this was required because not long after the site was commissioned they had an issue that required the 4 PST's to be drained down, this was done and soon after they were emptied they were found to be rising out of the ground, unfortunately despite filling them and loading them with concrete and lead ballast they could not be sunk back to their as installed positions and after complex engineering to reconnect the distribution pipe work, the tanks were left in a raised state and earth backfill was engaged to provide added support and remove the need for walkway edge protection. A new inlet works and pump system was built to introduce the extra head to the hydraulic circuit and happily the site has operated ok ever since. The tanks draining cycle had coincided with a falling spring tide so luck wasn't with the contractor doing the work and as the tide turned and came back in the tanks were floated and pulled their piles up, presumably estuarine sand silt and clay backfilling the pile sockets as they lifted.

Moxi

[richbee]

I belive the old type sceptic tanks are illegal now even if installed years ago.

They're OK and legal until they die and need fixing then the sewage hits the impeller cost wise.

I did see some comment on a contract for a flat we were buying for my stepson - something to the effect that in order to sell a house with an old-fashioned septic tank - you would need to have it replaced with a modern system within a year or something like that.
So not illegal, but highly frowned upon.
Ours hasn't been emptied since before we moved in >15 years ago, although it was more than 5 ft deep in s**T last time I looked

[Tinbum]

I belive the old type sceptic tanks are illegal now even if installed years ago.

They're OK and legal until they die and need fixing then the sewage hits the impeller cost wise.

I did see some comment on a contract for a flat we were buying for my stepson - something to the effect that in order to sell a house with an old-fashioned septic tank - you would need to have it replaced with a modern system within a year or something like that.
So not illegal, but highly frowned upon.
Ours hasn't been emptied since before we moved in >15 years ago, although it was more than 5 ft deep in s**T last time I looked

Yes i know of a local property that couldn't be sold until the septic tank had been replaced.