(a) Prime farmland soil removal, stockpiling and replacement. - (i) Soil materials to be used in the reconstruction of the prime farmland shall be removed before drilling, blasting, or mine related disturbances in a manner that prevents mixing or contaminating these materials with undesirable material.
- (ii) The A soil horizon, then the B and C soil horizons, either separately or in combination, or other suitable material that will allow for reconstruction of a root zone of greater productive capability to that existing prior to mining must be separately removed and segregated. Where it is impractical to immediately replace the soil horizon material or other suitable materials, each horizon separately removed must be separately stockpiled and properly identified. The Administrator may approve a plan which does not provide for the separation of soil horizons if the application can document by acceptable scientific procedures that removal of all topsoil in one step would not diminish prime farmland restoration objectives.
- (iii) During reconstruction of prime farmland soil, the C horizon material and then the B horizon material or a combination thereof shall be replaced first. The A horizon material shall be replaced as the surface layer unless the Administrator has approved an alternative segregation plan. Reconstruction of prime farmland soil shall include:
- (A) Replacement of a minimum depth of 48 inches of soil and other approved plant growth materials or a depth equal to the depth of a subsurface horizon in the natural soil that inhibits root penetration, whichever is shallower. The Administrator may require a depth greater than 48 inches whenever necessary to restore productive capacity due to uniquely favorable soil horizons at greater depths. Soil horizons shall be considered to inhibit root penetration if their densities, chemical properties, or water holding capacities restrict or prevent penetration by roots of plants commonly grown in the vicinity of the permit area and have little or no beneficial effect on soil productive capacity.
- (B) Replacement only on land which has been returned to a slope not to exceed premining conditions and scarified to reduce compaction of the graded spoil surface.
- (C) Replacement in a manner that avoids excessive compaction, so that the pore space of the soil, after reconstruction, is of a size, distribution, and amount which allows a favorable rooting zone; minimizes soil erosion; and restores an available water holding capacity consistent with the premining soil condition.
(b) Prime farmland soil stabilization, productivity, and revegetation. - (i) Following soil replacement, a vegetative cover capable of stabilizing the soil surface shall be established as soon as practicable. The revegetation soil amendments and mulching requirements of Chapter 4, Section 2(d) of the regulations shall be met.
- (ii) Prime farmland soil productivity shall be measured within ten years after soil replacement.
- (A) Soil productivity shall be measured on a representative sample, or on all the mined and reclaimed prime farmland area, using the reference crop determined under paragraph (C) immediately below. A statistically valid sampling technique at a 90 percent or greater statistical confidence level shall be used as approved by the Administrator in consultation with the U.S. Soil Conservation Service.
- (B) Restoration of soil productivity shall be considered achieved when the average yield during the measurement period equals or exceeds the average yield of the reference crop established for the same period for nonmined soils of the same or similar texture or slope phase of the soil series in the surrounding area under equivalent management practices.
- (C) The reference crop on which restoration of soil productivity is proven shall be selected from the crops most commonly produced on the surrounding prime farmland. Where row crops are the dominant crops grown on prime farmland in the area, the row crop requiring the greatest rooting depth shall be chosen as one of the reference crops.
- (D) Reference crop yields for a given crop season are to be determined from:
- (I) The current yield records of representative local farms in the surrounding area, with concurrence by the U.S. Soil Conservation Service; or
- (II) The average county yields recognized by the U.S. Department of Agriculture, which has been adjusted by the U.S. Soil Conservation Service for local yield variation within the county that is associated with differences between nonmined prime farmland soil and all other soils that produce the reference crop.
- (E) Under either procedure in paragraph (D) immediately above, the average reference crop yield may be adjusted, with the concurrence of the U.S. Soil Conservation Service, for:
- (I) Disease, pest, and weather-induced seasonal variations; or
- (II) Differences in specific management practices where the overall management practices of the crops being compared are equivalent.
- (iii) Areas where permits were issued prior to August 3, 1977 are exempt from the reconstruction standards of this Section.