Good luck with the project! The frost is very thin this year. I have an array of thermocouples in Rosemount, and most are not below 32 degrees at 10 inches on farm ground (last year we had frost down to 40 inches). The thick snow we had early this winter really kept the frost shallow. Last week, I even found some unthawed ground in a field that had 40 inches of snow over the top.