Civil engineer proposes deviations from the drainage plan

Hello,

my known civil engineer will install the drainage (rainwater and wastewater) for us.
We have a single-family house with rainwater downpipes on all sides of the house. The wastewater pipes are led out on one side of the house under the floor slab (3 pipes).
There is a house connection inspection chamber on the property that receives all pipes (combined system).

According to the drainage plan, all rainwater pipes (+ drainage pipe for the heat pump) are combined or run around the house on 3 sides and then slope down into the inspection chamber. The wastewater is also led into this chamber via a separate pipe on the short side of the house.

2 inspection chambers for rainwater and 1 inspection chamber for wastewater are planned.

The civil engineer now wants to split the rainwater pipe: 3 rainwater downpipes according to the plan but connect 1 rainwater downpipe to the wastewater pipe to save pipe length.
He wants to do completely without the inspection chambers.

I also believe he envisions a step change in the pipe somewhere (nominal diameter change).

My question in advance: Is this execution basically okay?

Please insert the drainage plan, that would be very helpful.

I would not do without inspection shafts or at least one. If something happens, it is very convenient.

Best regards
Gabriele

No one can answer that. Whether wastewater and rainwater may be combined, or whether one or more inspection shafts are required, is specified by the development plan or the municipality.

No one can answer that. Whether wastewater and rainwater are allowed to be combined, or whether one or more inspection chambers are required, is specified by the development plan or the municipality.

That is indeed the case. Doing so leads to financial consequences such as the recalculation of the discharge fee, etc. Not to mention the costs of dismantling.

My expertise: about 30 years ago, I worked for about a year in the lower water authority (so don’t rely too much on that).

The answer is relatively simple. Do what is stated in the development plan. You cannot cover up missing inspection shafts. But do whatever you want, you will have to bear the consequences.