Manhole cover - enlarging hatch

[stocks1j]

Hi All,

I have a manhole in my garden that requires reducing, the cover is in the middle of my lawn and is unsightly as well as being highly corroded is incredibly dangerous.

The manhole is used to service a septic tank as I live in the countryside with no mains sewage. I have attached some photos which show is it not built up by brick but solid concrete.
My aim is to reduce the manhole and use a recessed manhole cover from a company called ecogrid which you can then fill with soil and seed. The manhole cover I purchased is 100mm in depth so the plan was to set a concrete saw to 100mm, cut the shape of the manhole. Use a breaker to break out any further concrete and install.

Is this the correct methodology and is there a specific concrete saw / floor saw I should be using?

PS, this isnt my first rodeo, this girl can DIY and has renovated 2 houses previously! Just my first outing with a manhole. My brother is kindly helping with any heavy lifting!

Thanks,

Jade

 

[scbk]

I dunno, I know you've already bought a recessed cover, but I would be tempted to replace with a normal manhole cover and just put a plant pot/garden gnome on top of it!

Doing work like you're suggesting over an open septic tank cover is a pretty grim and risky job.

Also a grown over recessed cover will be harder to find in future years

 

[CBW]

Imo, I wouldn’t be taking a breaker or concrete saw to that, you could cause more harm than good. You’ve only mentioned 100mm depth nothing else, so presumably fits. If it needs reducing, then by hand might be less risky.

 

[cdbe]

Fix a board in the hole to catch the debris, cut slots with your grinder about 10mm apart and break off with a hammer, repeat till you get to the required depth (a bit deeper to provide room for a bed). If you hit rebar (lots of sparks) you may need to splash out on a suitable "turbo" diamond blade.

 

[freddiemercurystwin]

Whatever you do some H&S common sense should be observed, fall in there and you ain't coming out easily.

 

[CBW]

fall in there and you ain't coming out easily.

Or smelling pretty

 

[noseall]

View attachment 305948

Hi All,

I have a manhole in my garden that requires reducing, the cover is in the middle of my lawn and is unsightly as well as being highly corroded is incredibly dangerous.

The manhole is used to service a septic tank as I live in the countryside with no mains sewage. I have attached some photos which show is it not built up by brick but solid concrete.
My aim is to reduce the manhole and use a recessed manhole cover from a company called ecogrid which you can then fill with soil and seed. The manhole cover I purchased is 100mm in depth so the plan was to set a concrete saw to 100mm, cut the shape of the manhole. Use a breaker to break out any further concrete and install.

Is this the correct methodology and is there a specific concrete saw / floor saw I should be using?

PS, this isnt my first rodeo, this girl can DIY and has renovated 2 houses previously! Just my first outing with a manhole. My brother is kindly helping with any heavy lifting!

Thanks,

Jade

Looks like a reducing 'biscuit' that fits on top of a large pit.....

Don't attempt to cut or break it.

 

[JohnD]

is incredibly dangerous.

You have a septic tank.

The tank has an access trap.

Why is it incredibly dangerous?

 

[freddiemercurystwin]

You have a septic tank.

The tank has an access trap.

Why is it incredibly dangerous?

I think she just means it's dangerous because the lid is highly corroded.

 

[John D v2.0]

If the requirement is grass, I feel like a couple of tonne bags of top soil and a box of grass seed might be the best option for getting the level to match here!
I don't quite understand how planting grass in a <100mm deep tray is going to work out though, surely it would be sodden in winter and dry out constantly in summer?

 

[freddiemercurystwin]

It's a recessed cover designed specifically for planting over.

 

[John D v2.0]

It's a recessed cover designed specifically for planting over.

I know that, but I still don't understand how that would work in practice. i realise it's likely to be a compromise, so maybe that's the answer.

 

[freddiemercurystwin]

You bung some soil in it and then slap a bit of turf on top, what don't you understand?

 

[noseall]

'Access' is the key word here. All recessed lids, become difficult, if not impossible to lift, once they are filled and in place for a while. Once grown over, it will be difficult to locate as well as impossible to lift, without ripping the whole assembly out of the ground.

I'd replace with a decent cover and leave well alone.

 

[noseall]

You bung some soil in it and then slap a bit of turf on top, what don't you understand?

I think he means the concept is flawed/impractical and so do I.