The drain is offset to the back, i.e., a right-rear corner drain. It is an Elkay EGUH2816R. I don't know if you can tell from the picture, but my drain stub-out comes out farther from wall than the GD drain, and then the P-trap loops backwards to meet the GD drain tailpiece. Thus, I can see your contractor's concern. The drain stub-out perhaps did not need to come as far from the wall as I made it. As you can see, I offset the drain stub-out from the center of the sink drain by 6" or so. I think that if I had placed the stub-out in line with the drain, I could have gotten everything to work. I would have had to have had a shorter stub-out, and then turned the GD tailpiece a bit to one side (by rotating the GD). This probably won't make you feel any better, but I filled several pages in my notebook with calculations before deciding where to put the drain stub-out! (In my case, I was trying to accommodate both this sink and some future homeowner's unwise decision to use a sink with a center drain.) Here is a link that might be useful: Elkay Elumina

Thanks for your photos and replies. Yes, we want the soap dispenser also. That's why we want ONE faucet for the instant hot and filtered water. That would be at least three "things" in total on the counter behind the prep sink: one faucet for instant hot and filtered water, one regular faucet, and one soap dispenser. Maybe four...disposal air switch as well? I was thinking of an undermount prep sink that is about 15" by 15" inside. I think it will work on the counter; I'm more concerned about underneath. I figure the rest of the cleaning supplies will be under the main clean-up sink and the dishwasher air gap will be there, too. Maybe I need to just buy all of the products ahead of time and see how it fits.

I've done this job; it ain't all that. If you're really fussy, I'd smack the cabinet front off and the break up the cabinet bottom. Run the pipe as necessary under the cabinet, no concrete breaking required. Stub the new location, cut a new bottom, slide it into the dadoes in the cabinet sides, and reinstall the cabinet front. Plumb from the new stub.

Hi All - OP here. Let me clarify. "...why are you doing this if you have a place for the sink and disposal ....on a wall " ---- No room on the wall! "You have to have a sump engineered into something like that too" ---- The Drain Pump (Liberty 404) is the "sump" "And none of this will pass inspection." ---- Not being inspected :-) "We cut concrete all the time to do just that." ---- Cannot cut thru concrete due to radiant heating tubing laid when the house was built. "Pumping up into the attic and back down?" --- No, not to attic. Drain Pump is going to pump water from Prep Sink about 7 feet horizontally, then up about 1 foot vertically to meet the drain from the Main Sink. Still open to comments and suggestions. And photos if you have them! Thank you.