Septic hole repair

[PerranOak]

We have a septic tank system which is brick-lined and topped with standard, rectangular, covers. The problem is that, over the years, these covers (or, more precisely, the seatings) have become rusted and frayed.

I want to replace them but, of course, the old ones are still in situ and, in places, are quite firmly embedded.

What is the best way to deal with this? I wondered if I should use an angle-grinder to cut-out the old ones and provide a good keying for the new ones? What kind of concrete product should I use? Are there any pitfalls - other than falling in the septic tank(!) - that I should bear in mind?

I'm not looking forward to this, given the disgusting nature of the tank, so any all advice is welcome.

Cheers.

 

[RandomGrinch]

I'm not looking forward to this, given the disgusting nature of the tank

Could it be worth having the tank emptied and steam cleaned by the pro's before starting?

 

[Deleted member 292770]

A&E

 

[PerranOak]

Yes, that's a good idea.
A&E?
I still don't know how to go about fitting it though.

 

[Burnerman]

If the original frame is cast iron then I guess some of the cement flaunching will have failed?
Time to remove the old stuff right down to brickwork, then bed in the new frames with 3:1 sharp sand / cement mix. You may have to cut through the old metal with an angle grinder, but don't disturb the brickwork if you can.
Check the required sizes of chamber cover are available, and if it's an inlet or outlet chamber you are talking about, check the condition of the benching at the same time. You can get plastic frames with galvanised tops if you want.
John

 

[Nige F]

Send some pics. things may be better or worse than described

 

[PerranOak]

Thanks all. Can't send photos: the last time it was emptied about half of the surround fell into it! I had to place the cover back on and, basically, bury it in soil - couldn't face fixing it in winter!
It's definitely gone though - rusted all round and missing in places.
The concrete that held it in place (flaunching?) is mostly but, inconveniently, not all gone.
I've all ready got new covers (galvanised) that came with plastic surrounds. I replaced the covers and kept the surrounds in the shed.
The brickwork seems fine just the concrete on the top that's ratty.
Benching?
How do you actually fix the surround to the concrete? Do you do it all at once (my mixes tend to "flow" a bit) or build-up part of it then let it cure then put on the surround some how?
BTW is there a good ready mixed version to save having half-bags of sand and cement hanging around? - this is my only job.

 

[Burnerman]

You need to remove all of the cast frame and the sand / cement that was holding it down.....carefully does it with a hammer and chisel. If any bricks loosen, bed them down before you go any further. An angle grinder may help too.
Once that’s done, a good bed of stiff mortar is used to flow over the edges of the new frame....use a spirit level and feel free to tap the frame down - but do get it level or the lids won’t fit.
If the mortar is runny, stiffen it by adding more dry mix.....don’t skimp on the quantity, but don’t let it drop in!
Benching is the pointing around the pipes at the bottom of the chamber. It directs solids in the right direction and prevents rodent access.
John

 

[HERTS P&D]

For safety reasons, I would say this is a 2 man job.

Andy

 

[Burnerman]

It sure is, if you drop in Andy
John

 

[HERTS P&D]

John, I've fallen into a few manholes before while jetting and waling backwards.

Andy

 

[PerranOak]

The wife will never "spot" me on this!

I'll tie a broom handle to my back!