Is your 9b zone somewhere very hot or just temperate? (I am assuming hot). I think the drainage could be a problem during the warmest parts of the year, you might have to water several times a day just to keep things alive. I've found that even regular lasagna beds don't work properly if the plants can't get down to the soil at the base.

I guess it depends on what you want to plant, too. Rosemary and cacti would probably love it. :)

You could also try advertising on Craigslist or Freecycle to see if anyone near you would come take the rocks. "Free to anyone willing to do the labor" might get more results than you think.

Why can't you get equipment onto it? Fences can be disassembled to allow equipment in. Buildings, trees and boulders cannot.

It sounds like you need a front end loader and dump truck to haul away the stone. Then do you want to refill the garden with soil? If so the same drivers can bring in new soil or landscaper's mix and spread it out.

Be sure to check with any neighbors who might be affected by changes in drainage on this project. You are not allowed to flood someone else's property.

Why all the gravel? Are you near a river or creek that has a history of flooding?

I'm not sure I really follow the OP's post, but disassemble the fence and get a walk-behind front loader in there - they can fit in 42" of space, IIRC. Otherwise you will be miserable.

Dan

Unless there are other underlying problems with that gravel the drainage should be pretty good, maybe too good. It may be that this gravel was a misguided attempt to solve a drainage problem, too. The plastic is going to be a problem for a long time since it is difficult to remove and is falling apart now, but the solution for you is to add organic matter to this soil, as much as you possibly can. Where you want to plant a garden this year maybe purchasing large amounts of compost for that area and planting cover/green manure crops in other areas. It probably is not cost effective, or even desireable, to remove that much of your soil.

Kimmsr has a valid point. Most people including me want it done right freakin now. So, My idea is look around for a guy with a small 4x4 tractor with a loader and back blade. I'll take a while to dig out a foot of gravel and rock but when it's done it's done. Start over with dirt and large amounts of organic material. I like horse poo myself.