Frost line depth in Riley County, KS
How deep the ground freezes in Riley County, KS
24 in. Dig to 24 in, just below the frost. Nearest NOAA station: Tuttle Creek Lake, 7.5 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.