I'm planning to take up an old garden patio and lay a new one. However there is an ugly raised drain cover in the middle. This is for inspection of the property's drain at the point where it connects to a communal drain.
The drain sits 4" above the current level of the patio, so I would like to a) modernise the look of this drain, and b) lower it so that it's flush with the new patio. Raising the patio is not an option as the current level is ~17cm below the damp proof coursing and I've read that it shouldn't be any less than 15cm below.
The drain cover measures 20"-26" (imperial because it was built in 1969). The frame (which I believe is called the crown?) measures 24"-32". The top of the crown is 4" above the patio level.
Now I seem to have two options:
Remove the crown and replace with a flat manhole cover. Raise the patio level fractionally to get it flush.
Remove the crown and replace with a recessed manhole cover, which will look nicer because it can be filled with slabs to match the patio. However I would need to drop the height of the drain to do this, as being recessed it would need to be based lower than the patio level.
So my question regards the process of doing this:
I have read that the crown should just lift off (2 man effort). Is this likely to be correct? I'm going to assume worse case and it's secured somehow - how can I safely remove it without damaging the drain (and making me unpopular with the neighbours!).
Presumably I can lower it by removing one of those concrete "rings" in the picture and then building it up again to a lesser height? How would I go about this? It feels a bit beyond my capability (no building experience).
What size manhole cover should I be looking for? Most places only seem to stock ones like these that state 18"-24" which seems too small, but that is perhaps the cover size? And then they don't state the frame size. I did find this recessed one which states size including frame and would fit, but would require lowering the drain.
My preference would be to have a nice recessed cover but I think this may be beyond my capability. I have somewhat basic DIY experience (fixing things to walls, painting and decorating, replacing toilet flushes etc - no actual building work).