Seed in Rabbitbush and scallion seed now. Both of them lock up metals, and you can use em for starter compost for the trees later. Both are great recyclers, and if tests come back leaded, you can just ship em off for landfill.
You should check out The Ashevillage institute. It's just south of downtown off of Biltmore Ave. http://www.ashevillage.org/
If you want a good education in cover crops, this free download will do the trick.
In your climate, you could grow a lot of organic material between now and next spring, as well as putting a lot of natural, useable nitrogen into your soils.
Have you a plan to document progress with pictures and/or video?