Rehabilitating Herbicide-Heavy Soil?

Hey guys, I’m looking at houses right now and wanted to throw a vegetable garden in the back yard. I just saw one I really liked BUT the homeowner mentioned that they had big weed problems in the backyard until they started hiring someone to come by once a year and put down “some kind of fertilizer” that seemed to stop them all from coming up. I’m worried this is probably a pretty harsh herbicide that could be in the soil and get in the way of the garden. Do you know if there’s any way to remediate something like this? Would it be safe to dig out a section and put in some hugelkulture beds? Could I throw in some super deep raised beds to create a standoff between whatever those chemicals are and our root zone? Or would I have to worry about whatever those chemicals are leeching through the soil either way? I’m working right now on getting a list of what’s actually been put on the lawn, will update later if I’m able to get my hands on that!