Paul,
I live in the south, and all I have here is clay. I currently do all of my vegetable gardening in raised beds. Here is what I did.
1. I built the boxes for the beds out of regular 2x10 lumber and made them 4 feet wide and 8 feet long.
2. I placed the box in the area I wanted it and marked the inside area.
3. I removed the box and dug down 6 to 8 inches, removing all the soil.
4. Once I had all the soil removed I made sure I had all the grass out of it and started adding compost, manure, shreaded leaves, and the original soil back. I placed the box frame back over the hole and kept filling with this mixture until I had reached the top of the frame.
This may seem like a lot of work, and it is, but I have not been sorry I did this. I can now grow just about anything in my raised beds.
I hope this helped.
Jim Shearon
www.GardenerTalk.com