Grease interceptor above ground installation 

Depends on where you're at. Codes very from county to county.

But time flies and you didn’t explain to the rest of us knuckleheads what is incorrect that you have an issue with. Therefore your effort to reply is largely wasted effort if you meant to say it was done wrong. I take it you are just a proud individual who has to put others down to feel better. I hope not. Please, take the time and point out errors so that we all can learn from your education and experience. Thank you

You're not a knucklehead, and I can see how I came off egocentric. You never want a grease interceptor or sewer directly connected to any piece of equipment that has to do with food or the cleaning there of. You would need some form of way to create an indirect connection (restaurants usually have floor sinks) to allow any sort of backup to contaminate the sink. There are ways that you may achieve this (local codes will mandate it). Never leave water lines below sewer lines and surely not on the floor. The drain under the 3-comp will not stop a backup from the interceptor to the sink (hence the need for protection). The sink doesn't have a faucet for washing dishes (and there is plenty more wrong). I did not mean to be arrogant in any way, but this makes me cringe like watching a person put cheese on a taco after wiping the sweat from their brow. Good day sir.

I'll get it to you.

Schier GB-1 or GB-2

Vent yes, and it was added. Flow control?

@@ChampionPlumbing you might want to look up the flow control :)

the grease trap has a built in flow control

Yes, or the restaurant can clean them.

Use a wet vac

Twin cities metro.

Hey so how did you end up working yours out

Long sweeps are allowed under IPC

Yes! Where you from?

Champion Plumbing Canada, can only use them for venting here.

@@eddyhmmk1in Texas u can use those on back to back water closets, as long as the center of drain to center of flange is >18” to avoid sewer snakes crossing them. Really a double combo is preferred