But make sure you work the piles now, and then keep a lose watch on them as they might take a little from them at a time and 'expose' some more detecting opportunities.
They did some work on one major city park in Portland, Oregon several years ago and I found a number of 'V' and Buffalo nickels, a few Indian Heads and early 'wheat-backs' and more Barber dimes and quarters than I did silver Washington's and Mercury's.
They did a lot of digging and removal to build two new playgrounds, and they had a healthy start on it before we happened to come across it.
A week later I was at a smaller park where they had taken up some old pathway asphalt and widened it a bit. I got an Indian Head and a Barber dime. I spoke with the city worker who had dug it up and then was raking it out and he said they were going to be bringing in dirt from (mentioning the other park) and then covering it with new asphalt.
I asked where they were getting the dirt, knowing that there had been a lot of excavation at the other park for the new playgrounds. he told me where they had hauled all that dirt and that it was what they were drawing from to fill some of the sites they were working on.
An couple of hours later I was back and they had just finished spreading and leveling the fresh dirt. I got more Barber and mercury dimes, Buffalo nickels and Indian Heads from that. The next day they were putting down the asphalt.
I wasn't there, however, because I went to track down the dirt piles. It produced for me and a friend for the rest of the years with mainly older coins, a few tokens and some neat stuff. I hope your dirt pile will provide you with some memorable finds.
Monte
Monte