Drainage Overkill?

Hi guys

Not sure if this is the right forum for this (Could be building or garden?) but I thought this is the most relevant.

We have a new build that initially had small inspection chambers in the garden. On move in, these had actually been fitted at 600mm square covers. Its only a small garden at 8m x 6m so 5 of these sticks out like a sore thumb. We knew about them though so no gripes on that part.

Attached image is the drainage layout for ourselves (bordered in red) and two other plots (North on the drawing).

For any drainage experts, does the amount of manholes here seem excessive ?.

The 22.200 foul drain is only 4m away from the 22.475. (And there is another cover immediately adjacent to the fence in our neighbours property which was not even on this drawing, so I added it)

The same 22.200 foul drain is then only 5m from the 22.000 cover before it leaves our property.

Likewise for surface water, the 21.970 is only around 4m away from 21.850.

This feels like overkill as surely any issues at 21.970 could be resolved at 21.850 (or vice versa) and any issues at 22.200 could be resolved at 22.000 ?

interesting to hear some expert opinions

Thanks

Looks good to me with chambers where a number of runs meet and two disconnecting chambers at the boundary.

Thanks for the reply Denso.

Happy days I guess, atleast its been designed with problem prevention in mind. Even if slightly unsightly.

In terms of coverage, do you think I would be alright covering the two boundary chambers with either decking (Access via plank removal or a hatch) or having them sunk an inch below a gravel surface? (Could be the recessed drain covers if submerging is a no go)

General rules of drainage are, all runs must be in a straight line, chamber at every change of depth or direction and all sections of the system must be accessible for rodding if need arises. Manholes are expensive and time consuming to install, so will only be put in if deemed necessary, not quite sure why there are the 2 at the boundary, but I didn't design the system, and Building Control Officers can be anal at times over what they want to see before it's buried forever.