dishwasher in island without sink

[kitchenredo]

Trying to figure out the best way to drain a new dishwasher in a kitchen island where there is no sink.
--can I put an air gap underneath the counter? Don't want it through the counter for appearance reasons, and since there is no sink, why not?
--can I put the p-trap in the floor between the joists?
--can I install an air-admittance valve just above where I connect the dishwasher drain to the drain pipe, so that I can keep the installation close to the floor (to take up less cabinet space).
--so, the idea is a p-trap in the floor, coming up to a T-fitting, on top is an AAV, and coming off the side is the DW connection. This would be only about 8" off the floor. I would use a high-loop on the DW drain line (or air gap) coming down to this.

I've seen discussions about this issue online but never seemed to get all the details. Thanks, I appreciate any help you provide.

[phishfood]

The vent needs to be downstream from the Ptrap, not before it.

Putting the Ptrap under the floor is not a problem, as long as it is no more that 24" from the inlet of the riser pipe to the top of the trap.

I do believe that the air gap underneath the sink would be OK, but don't have my codebook handy to look it up, so maybe someone else will chime in. Without the open sink bowl to overflow, I think that I would go with the air gap instead of the high loop.

[LiQuId]

island vent... http://www.google.ca/imgres?imgurl=http://www.ilga.gov/commission/jcar/admincode/077/07700890ZZ9996kzR_files/image010.gif&imgrefurl=http://www.askmehelpdesk.com/plumbing/plumbing-island-long-drain-vent-pipes-246703-2.html&h=344&w=575&sz=12&tbnid=E_LdvwiXLjXp7M:&tbn h=65&tbnw=108&prev=/search%3Fq%3Disland%2Bvent%26tbm%3Disch%26tbo%3Du& zoom=1&q=island+vent&docid=RDXNyXFgjKp1NM&hl=en&sa =X&ei=PN4lT7e3J4ObiALeu5D-Bw&sqi=2&ved=0CF0Q9QEwBQ&dur=3

best if possiblle.. otherwise use a Air admitance valve on the trap arm.

if you go Island vent method install cleanouts to access tbhe drain and vent lines.

[phishfood]

Liquid's image:

[kitchenredo]

I have attached an image, I hope it comes out OK. Thanks for your comments so far.

--I can't install the typical island vent because there is no access to the vent stack from where it sits
--please look at the two ideas in the attached image and suggest which if either will work
--the dishwasher installation guide says the connection must be at least 18" above the floor if using a high loop. If instead I put a waste tee underneath the counter (is this allowed?), can I shorten the height above the floor like in design B?

Thanks, your comments will help me a lot.

kitchenredo guy

[phishfood]

Design A. As I stated previously, the vent needs to be downstream from the trap, not after it as in Design B.

[kitchenredo]

OK, now I get it. Thanks very much.