Healthy soil and sustainable growing

[Jennifer Hamilton <jenham@mac.com>]

I normally lurk on this list...but I need some advice. I want to start  
a garden on my new place, but I am now finding that the area I want to  
plant is probably construction fill. I'm finding lots of asphalt chunks.

Would it be worth my time to sift them all out or should I just go  
straight to raised beds? If I need raised beds, how deep should they  
be? I was originally thinking 12", but a local nursery advised 18". I  
hadn't really planned on needing to buy dirt!

Any advice would be appreciated!

Thanks.
Jennifer Hamilton
Santa Rosa, CA