Main line was leaking.. question about contaminated dirt.

Not sure if this is the right subreddit, but here we go.

My main line broke just outside my foundation and was leaking into the ground for weeks or months (the offset was pretty large). I noticed a small leak through the foundation around the pipe randomly that didn't seem to follow the precipitation cycle, but it took me awhile to come to the conclusion that it was likely a plumbing issue since the pipe penetration was known to leak during heavy rains.

Anyway, I had the pipe excavated and replaced in early January. They filled the hole back up with the same dirt that was excavated, meaning all the waste they inevitably dug up just went back into the ground. The area still hasn't fully settled (I expect it to take months), but eventually I will need to landscape the site again (had a couple plants and mulch that was removed prior). So.. how long until the surface is "clean" enough that I don't need to avoid working in that area? Anyway to speed up killing anything nasty leftover? Thanks.