Zoot's septic tank..

[zoothorn]

18 hours ago, markc said:

@zoothorn, no problem, first use a large stone of piece of brick to block the cavity, then use smaller rubble to fill up the hole. A strong sand/cement mortar will be fine as render on the crumbly surface, just work it in a bit and it will stabilise the block.

Understood markc thanks. I do have a heck of alot of cavity to fill. Hmm.. I'm wondering if Onoff's idea might be easier, just for me.. 
 

5 hours ago, Onoff said:

I'd first jet wash those sides to get rid of the greenery. I'd then get some 6mm galvanised garden mesh (Toolstation, Wickes). Stick bits of that over the holes with some blobs of CT1 etc and when dry and secure render over it. Nice sticky render laden with SBR. Build the render up in layers to replace where the block faces have spalled.

Hi Onoff. I can wire brush the sides I think to adequately ' jet wash'. Then the render that's left is mostly hollow, so Id think all needs removing. Then I can prep the crumbly block underneath. Would I need a strong 'sealer' then maybe to fix this 1st?

 

The mesh idea.. I think might be easier way for me. Will look into ct1 & galv mesh.
 

Thanks chaps, very helpful. Zoot

[markc]

Hi @zoothorn, 

Understood markc thanks. I do have a heck of alot of cavity to fill. Hmm.. I'm wondering if Onoff's idea might be easier, just for me..

you don’t need to fill the whole cavity, just block the top of the open ones where smaller stones would fall to the bottom.

[zoothorn]

On 13/10/2021 at 11:59, markc said:

Hi @zoothorn, 

Understood markc thanks. I do have a heck of alot of cavity to fill. Hmm.. I'm wondering if Onoff's idea might be easier, just for me..

you don’t need to fill the whole cavity, just block the top of the open ones where smaller stones would fall to the bottom.

Hi markc, Ive made a good start going with your fill holes with stones approach. One last hole to block tmrw/ will do a pic.

 

The render has been severley water penetrated behind it, meaning the exposed damaged block crumbly walls can just be scraped & a layer easily falls away, like rice krispies hundreds of small bobbles of concrete. scraped the weakest off.. but faces still weak.
 

Once ive hacked off all the popped render, I really need to 'fix' this block crumbly surface so its solid/ won't deteriorate & then can adhere some mortar/ render xyz on. Would this way be the right sort of idea? Thanks, zooter.

[TonyT]

how is the tank emptied? Is there lids on the top that you can access? cause maybe those large holes at the side also doubled up as the point where the hoses were pushed in to allow the liquid good to be emptied.

[markc]

@zoothorn, well done sir.

yes scrape off the worst of the crispies, wet the surface and push on a strong mortar mix (around 3 parts sand to1 cement, even 2:1) use the trowel to push it into the surface and it will get hold and stabilise the surface.

then you can use a standard mortar mix and small stones to build up the thickness to render level.

[zoothorn]

1 hour ago, TonyT said:

how is the tank emptied? Is there lids on the top that you can access? cause maybe those large holes at the side also doubled up as the point where the hoses were pushed in to allow the liquid good to be emptied.

Hi Tony, no/ appreciate the thinking.. but theres just a top hatch, these side holes are 2 decades of very frost rotten concrete blocks .

[zoothorn]

50 minutes ago, markc said:

@zoothorn, well done sir.

yes scrape off the worst of the crispies, wet the surface and push on a strong mortar mix (around 3 parts sand to1 cement, even 2:1) use the trowel to push it into the surface and it will get hold and stabilise the surface.

then you can use a standard mortar mix and small stones to build up the thickness to render level.

Ok that's a plan.. so what ratio mix, & what depth this 1st 'seal' layer? 
 

Even cloggging the holes with stones, I've still got many bits that go in 2" deepest in the crags between stones.. Ive hardly got a flat dry stone wall face in my little stoned cubby holes. Thanks zh

[Gus Potter]

Hello Zoothorn.

 

I take it you are in Scotland.

 

On 12/10/2021 at 13:20, zoothorn said:

Yup ok thanks IanR, no I didn't know this.. but its the wild west here/ might be different to england, & for the purpose of patchin up me tank which will be needed either way, I'm just going to crack on.

Once you get the smell from your tank sorted then your neighbours will visit more , you'll often find them quite refined and very sociable!

 

To immediate matters. From memory (Friday night)  the regs in Scotland changed a bit a ~ couple of years ago. Before that say going back 20 - 30 years many Solicitors would make sure the tank was registered with Scottish Water / part of the building warrant process if you were converting / renovating say. Solicitors were not that bothered about pollution but they did check to make sure you had rights to discharge the effluent.. so that drove it really at that time.

 

Part of the new Scottish regs is to build in the concept of "the polluter pays" so if your tank misbehaves the bill lands on your door step. Now, SEPA don't have an army of folk running round checking septic tanks. What they will do though is turn up if there is a complaint of pollution.

 

If I was you I would check to see if your existing discharge is registered. You may find this in your Solicitors' info. If not call them and ask why not in a "nice" way. If not applicable go onto the SEPA site and register an existing discharge. Oh and before calling your solicitor you can check SEPA's site to see if there is a registration... well there used to be before they got hacked?

 

The next thing to do is to have a look at the tank. Does it have a soakaway or a pipe the just leads straight to a burn / loch?

 

Often in Scotland if a soakaway then you have a little time on your side, probably not much as our modern living produces much more "solids / ammonia etc" than say an old cottage where folk didn't use so much bog roll, bleach etc.

 

If to a burn /loch then be careful and responsible. These old brick tanks are really small! don't hold a lot of volume.

 

As a stop gap what about just digging down the sides say 6 -9 inches, put in a bed of sand / hard core and some slabs .. like kerb stones to cover the holes. Don't try and seal it up completely as you may find that you start to blow the traps inside the house. Also, a lot of these old tanks are leaky.. and some of the liquid soaks away out the sides of the tank. I have seen some old cottage tanks where they never really fill up and use the soakaway. My Mum's is one, old lady on her own, old brick leaky tank in gravel ground.

 

If you really want to fill / point the masonry use a 1: 5 or 6 cement sand mix with a touch of plasticiser. Make it as weak as you can, if not it will just skrink away from the old masonry.

 

The main thing here is to apply common sense!

 

 

 

 

 

 

 

 

 

 

[zoothorn]

15 hours ago, markc said:

@zoothorn, well done sir.

yes scrape off the worst of the crispies, wet the surface and push on a strong mortar mix (around 3 parts sand to1 cement, even 2:1) use the trowel to push it into the surface and it will get hold and stabilise the surface.

then you can use a standard mortar mix and small stones to build up the thickness to render level.

Hi markc, good ok I missed your strong mix suggestion here. 3:1 it is ( plus bit of frostproofer for plasticiser.. unless im off track).
 

So this 1st strong mix.. sort of 1cm thick onto the krispies?  & use the same mix to fire into/ stabilise my packed stoned cubbyholes?

 

So much time & moisture got behind the popped render top, that the krispies have a layer of soil formed between. Plants grown etc (  close up photo in next post).

 

 

 

 

 

 

[zoothorn]

You can see the fallen brushed off stuff below/ may be able to see then just how brittle these faces are.

[markc]

Hi @zoothorn, sorry about the late reply, been a stupidly busy day.

the thin strong mix is just good at getting hold of a crumbly surface, but as someone else said the fill should be a weak mix to minimise shrinkage.

you are doing fine, and all theses small jobs are how we learn as the same techniques are used for bigger projects.

[zoothorn]

On 16/10/2021 at 17:27, markc said:

Hi @zoothorn, sorry about the late reply, been a stupidly busy day.

the thin strong mix is just good at getting hold of a crumbly surface, but as someone else said the fill should be a weak mix to minimise shrinkage.

you are doing fine, and all theses small jobs are how we learn as the same techniques are used for bigger projects.

Hi markc, sorry it seems you're left to help me alone! but shouldn't be much longer/ not a big job i hope.

 

So a 3:1 strong mix for the fixing/ sealing the face crumbles understood... & for firing into the stoned holes, say a 5:1 mix, built up in a few layers until maybe 1/2" from the outer render? ( is that a 'weak' mix?).
 

Then maybe a different mix for this final render layer I'm not sure/ will ask then. Appreciated, zoot.

[markc]

29 minutes ago, zoothorn said:

Hi markc, sorry it seems you're left to help me alone! but shouldn't be much longer/ not a big job i hope.

Good morning Sir, no problem at all.

 

So a 3:1 strong mix for the fixing/ sealing the face crumbles understood... & for firing into the stoned holes, say a 5:1 mix, built up in a few layers until maybe 1/2" from the outer render? ( is that a 'weak' mix?).

yes this sounds good, top/ render coat should be 3 or 4 to 1 but using grit sand instead of builders sand.
 

Then maybe a different mix for this final render layer I'm not sure/ will ask then. Appreciated, zoot.

 

[zoothorn]

@markc sorry you're reply seems its hone awol. Zh

[markc]

1 hour ago, zoothorn said:

@markc sorry you're reply seems its hone awol. Zh

Nope, my reply is within the quote from you, not easy to spot I agree

[zoothorn]

2 hours ago, markc said:

Nope, my reply is within the quote from you, not easy to spot I agree

Ah gotcha! Great thanks mark.

[zoothorn]

Hang on a tick.. is Grit sand "sharp sand"? I still dont know what ive got here.. its just 'sand' & a bit wet, from a builders yard. 

 

 

[markc]

18 minutes ago, zoothorn said:

Hang on a tick.. is Grit sand "sharp sand"? I still dont know what ive got here.. its just 'sand' & a bit wet, from a builders yard. 

 

 

Can’t be sure but I reckon it’s course sand.

there are loads of different sands but they can be broken down into 3 basic categories 

soft sand - fine often red in colour and used for mortar.

course sand, similar to soft but larger grains, often used in smooth rendering etc.

grit or sharp sand - ideal for concrete and textured render.

for your project I wouldn’t worry about it. Use what you have.

[Onoff]

I'm tempted to post you some sample pots of sharp sand, builders sand and all in one ballast! ?

[zoothorn]

11 hours ago, Onoff said:

I'm tempted to post you some sample pots of sharp sand, builders sand and all in one ballast! ?

As long as you don't send me any of your other sample pots..

 

Im going with markc/ just use my 'demarara sugar' sand above. I know what ballast is/ easy as its got stones in.

 

Afaict, the difference in sand is only a cosmetic thing-? As this wall side faces my n'bors, not me it only has to be functional. I aint super smoothing or painting it for eg.

 

 

 

[Onoff]

24 minutes ago, zoothorn said:

Afaict, the difference in sand is only a cosmetic thing-?

 

No it's a strength thing. Soft sand makes for a weaker mix than sharp sand.

 

If it helps then the sand you get in ballast is basically sharp sand. It's "sharp", coarse, has little bits of stone in it.

[zoothorn]

6 minutes ago, Onoff said:

 

No it's a strength thing. Soft sand makes for a weaker mix than sharp sand.

 

If it helps then the sand you get in ballast is basically sharp sand. It's "sharp", coarse, has little bits of stone in it.

Aha.. right this makes sense: the pale pinky render stuff Im hacking off seems weak/ often soft etc, & I see no sharp bits in: so maybe soft sand was incorrectly used.

 

I assume I can readily buy a 25 kg bag of sharp sand then, as i could this soft sand. Will scour the 'sheds' jewson etc. Thanks. Zh

[PeterW]

3 minutes ago, zoothorn said:

 

I assume I can readily buy a 25 kg bag of sharp sand then, as i could this soft sand. Will scour the 'sheds' jewson etc. Thanks. Zh

Yep you will find it as bagged sharp sand. You do not want building sand, soft sand or plastering sand .. 

[Onoff]

28 minutes ago, zoothorn said:

Aha.. right this makes sense: the pale pinky render stuff Im hacking off seems weak/ often soft etc, & I see no sharp bits in: so maybe soft sand was incorrectly used.

 

 

Could have simply been a weak mix (too much sand) or the weather has gotten at it, or the base wasn't properly cleaned and it didn't adhere. Or a combination of all 3. I know people who will chuck in one measure of sharp sand with the rest soft when they render. Makes for a harder render.

 

Good luck trowelling it on and not pushing any of your wedged bricks in. I'd have filled the gaps as much as I could with a mortar gun. That'd hold it all together and make for a nice nobbly surface to render to.

[zoothorn]

12 hours ago, Onoff said:

 

Could have simply been a weak mix (too much sand) or the weather has gotten at it, or the base wasn't properly cleaned and it didn't adhere. Or a combination of all 3. I know people who will chuck in one measure of sharp sand with the rest soft when they render. Makes for a harder render.

 

Good luck trowelling it on and not pushing any of your wedged bricks in. I'd have filled the gaps as much as I could with a mortar gun. That'd hold it all together and make for a nice nobbly surface to render to.

I think the 1st two, weak mix & weather's got at it (perhaps frost too if no protector in the mix?).

 

Why wouldn't people just not use soft sand at all then for render, if a chance it'll weaken it, why not just all shsrp sand?

 

Yes its this trowelling it on & not dislodging any stones is my concern. I think I might have done it wrong tbh, without anything supporting the big lowest flat stone in each cubby hole. Will have to redo with your mesh idea if it goes t*ts up & the base stone falls.. alot of work wasted if so. I might have to just 'fire some in' & pray it sets.. then come back & fire in more. Tmrw's job.
 

There's not a straightforward solution I dont think to spanning/ filling these cavities. Thx zoot