[Double-Eh]

I'm planning on building a front deck/porch on the front of my house. Off the sidemy concrete stairs and porch, in front of my living room window, between the house and sidewalk that leads to the back is a 6'x20' space that used to be a 'garden'.

I've ripped out that garden and re-purposed the top soil which had been nothing more than a crab grass haven. I dug down to the clay and now the area is about 8 inches below the sidewalk.

My thought is to fill it with clay and pack it. I then will install cement block footings and build the deck. My logic is that the clay will be at grade and allow for proper drainage away from the house. And with the clay packed down my footings should be fairly stable.

Am I out to lunch with this idea? I've been reading all kinds of stuff about crush gravel, had one person recommend not filling this water trap at all (no idea why)... Any thoughts would be appreciated