You can pretty much guarantee that the soil below the asphalt is contaminated with all sorts of chemicals. Routinely, the soil would be treated before the asphalt is put down to prevent any plant growth. Two or three feet of topsoil would help, but most large trees are going to tap through it and get the junk from below. I would remove at least 4 feet of the old soil if you plan on planting anything other than grass.

Asphalt : No mention of it, and none pictured.

Marshy : Busses could not have parked then; (maybe parked elsewhere then)?

Contamination : From busses, yes; and possibly fill material came contaminated. In addition to thinking about plant health, you must consider the health of humans and other animals that will eat the fruits.

There's no asphalt involved. This is a follow up to a thread that was last posted to 12 days ago. Some of the background from that thread:

"We recently purchased a home in southwest ranches, FL. The previous owners used one acre of the backyard for their bus company, as a bus parking lot, for many years. There is a layer of gravel that's so compacted, it feels like cement, covered in black plastic. We would like to turn this space into orchard. Is there a way to do it?

Our landscapers recommended we use a rototiller on the cement/gravel layer then add good soil on top."

...

"I am going to eat the acre of fruit harvests! This is not a commercial business. Just a hobby, my husband and I like to grow our own fruit and vegetables. We had 40 trees at our first property, that we planted, and about 15 at our second. There are three mango trees and a coconut so far on this property, but we figure we have room for up to 60 here..."

Supposedly Sunflowers can help clean up contaminated soils of heavy metals etc. You could get a soil test and then work in some good compost and plant the sunflowers and then try testing again..

https://news.virginia.edu/content/uva-undergraduate-researcher-studies-sunflowers-power-clean-soil#:~:text=%E2%80%9C%5BSunflowers%5D%20are%20able%20to,They're%20called%20'phytoremediators.

For sure oil and engine fluids dripped down and seeped into the soil over the years. I imagine there may be high lead levels as well. I don't think I'd want to grow anything to eat in it.

I also understand rototilling Florida's sandy soil can bring nematodes closer to the surface.

Something ornamental, a wildlife/ butterfly or entertainment area might be a better choice.

If you're determined to have edibles, perhaps removing the top layer of gravel, then mulching/composting/cover cropping to build up the soil for a year or so would help mitigate the contamination.

I think OP should find a place with at least enough room for an acre of orchard and move. Why put all the time and money putting in 60 trees and then be afraid to eat the fruit.

I apologize for my frankness.

Or find an acre. Moving need not be part of the endeavor.

>"Soil contaminants don't accumulate in tree fruit." ___ That statement contradicts many published tests.

( Conclusion section of one :

It included tree fruits.)