30 CFR § 823.12 - Soil removal and stockpiling.
(a) Prime farmland soils shall be removed from the areas to be disturbed before drilling, blasting, or mining.
(b) The minimum depth of soil and soil materials to be removed and stored for use in the reconstruction of prime farmland shall be sufficient to meet the requirements of § 823.14(b).
(c) Soil removal and stockpiling operations on prime farmland shall be conducted to—
(1) Separately remove the topsoil, or remove other suitable soil materials where such other soil materials will create a final soil having a greater productive capacity than that which exist prior to mining. If not utilized immediately, this material shall be placed in stockpiles separate from the spoil and all other excavated materials; and
(2) Separately remove the B or C soil horizon or other suitable soil material to provide the thickness of suitable soil required by § 823.14(b), except as approved by the regulatory authority where the B or C soil horizons would not otherwise be removed and where soil capabilities can be retained. If not utilized immediately, each horizon or other material shall be stockpiled separately from the spoil and all other excavated materials. Where combinations of such soil materials created by mixing have been shown to be equally or more favorable for plant growth than the B horizon, separate handling is not necessary.
(d) Stockpiles shall be placed within the permit area where they will not be disturbed or be subject to excessive erosion. If left in place for more than 30 days, stockpiles shall meet the requirements of § 816.22 or § 817.22 of this chapter.