Appraise my drainage design

[PSC88]

Hi we are currently at foundation stage and having to rework our drainage design, mainly as we demolished an existing bungalow and wanted to use the same connection.

 

In hindsight we should have dug a trial hole to existing connection and worked the falls backwards, however we relied on some old drainage plans which turned out to be a few 100 mill out leaving us with a very tight fall or having to raise the finished floor level by 300mm to gain the fall.

 

We had a review with our building inspector who decided shorter runs under the building to get the fall to work.

 

I have attached the image and the blue lines are our new proposed routes.

 

Ideally I wanted as much of the drainage outside of the building as possible but looks like this isn’t possible.

 

Any thoughts or advice positive or negative would be welcome 

[Nickfromwales]

4 IC’s too many here, if you can run these pipes under the slab however you want?

 

For my current client I simplified 5 IC’s down to…….. 1. Passed BC with flying colours, and had the BCO out today to do a stage inspection, all flying colours.

 

Architects go nuts on these, drainage ‘engineers’ not far behind, but sense / sensibility should prevail.

 

Zero sense appears to have been applied to the above, sorry.