Re: How close to the house?
I’d be starting with a serious soil test to identify what, if any, residues or contaminants you are dealing with. Not just pH, but to test for metals and toxins and so on. The State of Florida offers many:
Your local (county) extension service can direct you about getting thorough tests as well.
In urban settings where community gardens and other plots are often places where lead and other toxins have gotten into the soil, raised beds are often used, with the further barrier (in the bottom of the beds) of landscape fabric being installed. For instance, this project run by Brown University addressed the issues and “solutions” in a PDF.
I can’t give you the link (it seems to be broken) but do this to get the PDF yourself:
in Google search, enter “bay street area raised garden beds project.” The PDF should be the first result.