What must be enclosed in the primary container when shipping a soil sample?

• A. the instruction sheet on how to sample and send soils
• B. the soil permit certificate
• C. another durable watertight, secondary container
• D. a cooling agent

Answer: (C)

Shipping soil samples safely relies on creating multiple layers of containment. The interior holding the soil should be inside a separate, durable, watertight secondary container. This secondary container acts as a leak-proof barrier, so if the inner container breaks or leaks, the contents are still contained and won’t escape into the outer packaging or expose handlers. That protection is the reason this is required. The other items don’t address containment: an instruction sheet isn’t needed inside the container, a soil permit certificate isn’t part of the packaging, and a cooling agent is only necessary for temperature-sensitive samples, which isn’t the standard requirement here.