The US Occupational Safety and Health Administration (OSHA) uses 5
soil classifications:
Stable Rock
Type A - cohesive, plastic soils with unconfined compressive
strength greater than 1.5 ton/sf
Type B - cohesive soils with unconfined compressive strength
between 0.5 and 1.5 ton/sf
Type C - granular or cohesive soils with unconfined compressive
strength less than 0.5 ton.sf
Type C60