Frost line depth in Edgefield County, SC
How deep the ground freezes in Edgefield County, SC
no frost in a normal winter. Dig to 12 in, the 12 in code minimum. Nearest NOAA station: Edgefield 2.2 Ene, 4.1 mi.
Your building department sets the legal frost line depth (IRC Table R301.2(1)); footings must go below it (R403.1.4.1). Call them before you dig.