Frost line depth in Lebanon County, PA
How deep the ground freezes in Lebanon County, PA
20 in. Dig to 21 in, just below the frost. Nearest NOAA station: Lebanon 2 W, 2.6 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.