A Green Roof for the South Central Farmers?

While last Tuesday's eviction looked like the death knell for Los Angeles' South Central Farm, many of us in the Treehugging community have now shifted our focus, and began to wonder if there was a "win-win" that could be salvaged from this otherwise bleak situation. In response to a post at sustainablog (note: I am the author and publisher of sustainablog), a reader offered an idea that has the potential to make everyone happy: a green roof on the planned warehouse where the farmers could continue to plant and harvest their crops. Brian Green, the reader who suggested the solution, described it like this:
If [developer Ralph Horowitz is] building a warehouse, why not simply build up a stronger roof and have it be an earth roof where they can continue farming? Is that in some way illegal? That way you get the warehouse AND you get the farms. So what if you have to walk up a flight of stairs before you get there? Warehouse roofs are flat, cover it over with two feet of good earth and then plant away. Irrigation isn't a problem either. Just run lines from the water supply of the building. Put in meters. Done deal. In fact, I think more warehouses ought to be built with stronger roofs for precisely this reason. Can't they be retrofitted?
In a subsequent comment, Brian expanded on the idea:

It just sounds like common sense. Think of all the flat buildings you see everyday. Think of all those warehouses. Certainly there'd be issues with the additional weight, but engineers get paid for that sort of thing.

Imagine being able to turn all warehouses into gardens and parks. Could you imagine how much that would change a city? The view from above would be surreal. Imagine putting walking bridges between buildings. Imagine that the new public space is actually above ground level. Why not? It's the best use of the space.

The water runoff probably wouldn't occur at all if it was a garden. The plants would suck up the water greedily and the irrigation that would be used should be the ultra-efficient "drip irrigation" and therefore seriously cut down on the costs of water.

I think as people start to look at cities and want to use every square inch as efficiently as possible, they will begin to see the same things as I do.

The response among the Treehugger staff, as well as the folks at Groovy Green, has been overwhelmingly positive: the word "brilliant" has been thrown around a number of times. While we recognize that this solution would require overcoming a number of challenges (the engineering of the building, the agreement of the developer and other involved parties, the satisfaction of insurers, etc.), we thought we'd solicit the feedback of our own brilliant readers. What do you think of this idea? Despite the challenges, do you think it's feasible? What other challenges might planners and developers need to consider before embarking on such a project? We're very interested in what you think about this idea! :: sustainablog and Hugg