(aka the Logan Triangle)
Philaphilia's GroJLart has on Naked Philly a feature about the ruins of the Logan Triangle, a region of subsiding land due to poor fill over the now-turned-into-a-sewer Wingohocking Creek. This area came to be because the dwellings there were simply made uninhabitable--which, of course, means that all but the most marginal uses of the site would have to deal with the sheer expense of environmental remediation.
The park sounds good in concept, but rapidly runs into a slight problem: it would be immediately across the street from the similar-size Hunting Park, which already has maintenance issues of its own. If we can't afford to maintain Hunting Park, why on earth should we put another Hunting Park right next to it?
The tree farm would not be yielding foodstuffs, so it can use the land as-is.
Urban agriculture would be yielding foodstuffs. The ground is contaminated. However, similar conditions don't stop Greensgrow. Like operations could certainly be set up throughout the area.
The golf course sounds like a pretty decent idea--but what about the contamination? And a larger issue--how would you market it? It seems like only an Arnold Palmer-designed course or something along that vein would be able to attract the golf-club set to that neighborhood.
The solar farm doesn't need to worry about contamination, but will still need to worry about subsidence. Industrial-scale solar panels are very delicate.
--And all of these have to sort out the ownership situation. The original subdivision was for residential properties; since, however, the conditions of the Logan Triangle prevent residential development, a core need is thus to ensure all the properties in the Triangle are consolidated before they are re-subdivided for whatever future use(s) will exist on this site. This will likely take the form of block conferral. Consolidating all these blocks into superblocks would still be detrimental to the long-term access of the site, and should not be considered short of a use necessitating a superblock (like a golf course).
The most likely result should be a variety of agrarian uses springing up on each block--tree farms, food farms, and solar farms--with perhaps a narrow band of commercial fronting the Boulevard (depending, of course, on the viability of the ground conditions). This could be done as a farmer's market--a wholesale space for each of the ten-to-fifteen or so potential properties within this site. Furthermore, the site can be developed through a collaboration between successful urban ag operations (Greensgrow, the Mill Creek Farm, etc.)--particularly those dealing with raised-bed operations--and the Logan neighborhood, so that these farms are not just some outside operation, but an important source of revenue and foodstuffs for the neighborhood itself. This, of course, provides work and ownership in one of the poorest parts of the city, and so catalyzes a local reinvestment cycle.