Base Cabinet drain re-route

Scenario
In a kitchen remodel, and discovered a complication. The builder ran a 1-1/2" drain pipe behind the base base cabinets along the wall. Unfortunately, where the horizontal drain line is, to the left of the sink, the wife wants pull-out trash bins. Said bins will interfere with the drain line. The wall itself is a 2x4 exterior wall, so routing the plumbing inside the wall - through studs - isn't feasible.

Routing Question
I'd like to route the drain pipe down, then along the floor (so below the base cabinets - and hidden by toe kick), and back up again through the bottom of the sink base cabinet. I tried my best to indicate with the red lines how I'd like to do this. Essentially it creates a double trap. Is this a legitimate method to accomplish what I'm trying to do?

Pipe Selection Question
The pipe shown in the picture, as well as the vertical (in the wall) are 1-1/2" ABS. As I turn down from the wall, should I open it up to 2" pipe to help the water drain better due to less drag? Or does the 1-1/2" bottleneck at the vertical negate that logic?



Thanks for reading
David

I don't see a vent. Without a vent before the drain turns downward after the P trap, you have an illegal S trap.

Can is use a tee and a ready-vent?

Any value in upsizing the new drain line, or should I just do the whole thing in 1-1/2" to keep things simple?

You absolutely CANNOT do what you show. It would violate EVERY code and good plumbing practice, besides creating a nightmare for you when you use the sink. Why can't you run the line inside the wall. With the window above it, the studs are NOT "structural" and we ran drain lines inside 2x4 walls for "decades" before 2x6 walls became common. You also cannot "upsize" a drain line and then "downsize" it again. Also a major violation.

Thanks HJ. Appreciate the feedback - especially so quick and before I got started down that path.

Unfortunately I have a gas line running vertically in the wall along the way to the sink, so I won't be able to run this in the wall. I'll run it inside the base cabinet and just figure out something for the trash bin.

Why is there a gas line there? It appears to be a "short wall" under the window so it cannot be going too far upwards.

wife wants pull-out trash bins.

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The plumbing takes presidence over trash bins.
That's why you have a plumbing inspector, and plumbing permits.

You absolutely CANNOT do what you show. It would violate EVERY code and good plumbing practice
hj

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you can do it your way sort of just don't go up,
go down and tie in under the floor !

and yes you still need to run vent up though roof CA plumbing goes by the UPC.
and requires vent though roof !
where the black abs meets the white painted abs throw a Wye in the line run it up under window then back over to tie into existing vent,
make the existing drain tie in a clean out and cut back into pipe under the floor that is the way a plumber might run it and meets code, and practice,
and your wife can have her trash bins

Remember with drains it is always down and never ever up