[Pizza Freak]

Thank you gjbingham & cvdukes for your replies.

To answer your questions cv, yes, the 16% grade is a rise of 16 feet over a 100 foot run. It doesn't seem like much, but we literally don't have a flat bit of land on the property. The retaining wall is made of pressure treated wood (which concerns me, of course) and was constructed in 1998 along with the house. It was, fortunately, over-engineered and is quite solid. I don't see it collapsing. There is a french drain at the base of the wall. Our cement patio meets up with the retaining wall. There is no backfill behind it...it is all native, undisturbed soil. The soil itself is fairly sandy with clay & gravel farther down. If you go deep enough, you'll hit sandstone. The soil is not shifty, but we do have some erosion, mainly thanks to the gophers.

I should note that we only get rain in the winter here. The soil never freezes, so heave is not an issue. We can get anywhere from 25" to 35" of rain in the winter. The soil will be soggy all winter and bone dry all summer.

So, yes, I'll need to cut into the hillside a bit to accomodate the hearth, and the front of the oven will be directed towards the retaining wall (downhill). I'm essentially using the hillside as my "stand". I suppose my main concern is having the hearth sitting on the ground and being subjected to moisture during the winter (I'll want to use the oven in the winter, of course). Perhaps a good gravel base would help? Obviously I'll have to put in footings, a small retaining wall behind the oven, and some sort of french drain to pull water away from the hearth/oven. I'm toying with the idea of pouring a slab and making a short stand on which to pour the hearth. This would get the hearth off the ground and raise the height of the oven a bit, but it would add cost to the project. I'd prefer just to have the hearth on the ground.

Thanks for any wisdom you can supply. I'll only have one shot at this, so I want to do it right!
Pizza Freak