30 CFR § 57.4104 - Combustible waste.

(a) Waste materials, including liquids, shall not accumulate in quantities that could create a fire hazard.

(b) Waste or rags containing flammable or combustible liquids that could create a fire hazard shall be placed in the following containers until disposed of properly:

(1) Underground—covered metal containers.

(2) On the surface—covered metal containers or equivalent containers with flame containment characteristics.