The 2019 Residential Code of Ohio states:

404.4 Retaining walls.

Retaining walls that are not laterally supported at the top and that retain in excess of 48 inches (1219 mm) of unbalanced fill, or retaining walls exceeding 24 inches (610 mm) in height that resist lateral loads in addition to soil, shall be designed in accordance with accepted engineering practice to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Retaining walls shall be designed for a safety factor of 1.5 against lateral sliding and overturning. This section shall not apply to foundation walls supporting buildings.

The frost depth varies, but generally non-flexible walls must be embedded a minimum of 30 inches to get below the frost depth in Ohio. Segmental retaining walls do not need to embedded below the frost line due to there flexibility.

DIY Retaining Wall provides engineering services in Ohio.