The gravel harvest does not seem to have sprouted

[concertinette]

Yesterday, I was digging around in the side bed, that was previously entirely hosta and sedum, but is destined to be (after phytoremediation de-leading) my part-shade greens garden.  I discovered that it was a half inch of mulch over about 4-5 inches of soil, over about an inch of gravel, over black plastic.

Concerns:

• Is there a lot more lead underneath that black plastic?
• Should I have left it in place?
• Given that I caught the whole thing on a garden rake and tore it out, I have gravel mixed through all that soil.  Highly irritating.
• What, did they think the gravel was going to sprout and they'd start a home-grown quarry?
• This is along the fence, and the neighbor's shrub seems to have lots of roots, maybe that's what the plastic was about?
• This is the area I was going to be seeding Indian Mustard over for deleading the top couple of inches; once i do that, stirring is against the rules.  Should I degravel it, or ignore that?

So, like many things in my yard and life, it is half-resolved.  I know there's more plastic under the adjacent section of bed, but I haven't dug it up yet.  I don't think I'll be taking a new soil sample for a lead test.  The soil level is just barely up to the sidewalk; I could easily add some of my nice new loam.  But I'm imagining the lead-leaching plants doing a better job on undiluted soil, so I'm thinking maybe I'll set a barrel-ful of loam aside till I harvest that crop of heavy-metals.