Parking Garage Drainage

[UDP10]

I've recently been asked to review the drainage design for a new 7 story, open ventilation parking structure. No oil interceptor is provided. I can't find anything in the local codes that requires it, but I would think it's good practice? In a tight budget, is this necessary?

Also, is there a reference for parking structure drainage design? I'm struggling with sizing the conductors. The lower floors would be exposed to very little rain, so I think a typical storm system calc based on area would be overkill. Advice?

 

[PEDARRIN2]

I would ask the local code authority.

In some locations, the drainage goes to the storm system - in others it goes to the sanitary.

Where I am at, they want it to go to the sanitary. We use a combination oil interceptor and master trap. It is basically a sealed and vented manhole that collects water. It kills two birds with one stone - it intercepts the oil and it prevents the drain traps from freezing.

As far as sizing the conductors - I would think that any floor that is not open above to the elements could be sized with a 4" or 6" drain pipe. These floors would get some rain fall from the sides but that would be minimal. Any level that is open to the elements from above would need to be sized as a storm system.

Of course that is just my $0.02 on it.