La. Admin. Code tit. 43 § XV-5407

Current through Register Vol. 50, No. 9, September 20, 2024

Section XV-5407 - Backfilling and Grading: General Grading Requirements

A. The final graded slopes shall not exceed in grade either the approximate premining slopes, or any lesser slopes approved by the office based on consideration of soil, climate or other characteristics of the surrounding area. Post-mining final graded slopes need not be uniform but shall approximate the general nature of the premining topography. The requirements of this Section may be modified by the office where the surface mining activities are reaffecting previously mined lands that have not been restored to the standards of this Chapter and sufficient spoil is not available to otherwise comply with this Section. The person who conducts surface mining activities shall, at a minimum:

1. retain all overburden and spoil on the solid portion of existing or new benches;

2. backfill and grade to the most moderate slope possible to eliminate the highwall which does not exceed either the angle of repose or such lesser slope as is necessary to achieve a minimum static safety factor of 1.3. In all cases the highwall shall be eliminated.

B. On approval by the office in order to conserve soil moisture, ensure stability, and control erosion on final graded slopes, cut-and-fill terraces may be allowed, if the terraces are compatible with the approved post-mining land use and are appropriate substitutes for construction of lower grades on the reclaimed lands. The terraces shall meet the following requirements.

1. The width of the individual terrace bench shall not exceed 20 feet, unless specifically approved by the office as necessary for stability, erosion control, or roads included in the approved post-mining land use plan.

2. The vertical distance between terraces shall be as specified by the office, to prevent excessive erosion and to provide long-term stability.

3. The slope of the terrace outslope shall not exceed 1v:2h (50 percent). Outslopes which exceed 1v:2h (50 percent) may be approved, if they have a minimum static safety factor of more than 1.3, provide adequate control over erosion, and closely resemble the surface configuration of the land prior to mining. In no case may highwalls be left as part of terraces.

4. Culverts and underground rock drains shall be used on the terrace only when approved by the office.

C. Small depressions may be constructed, if they:

1. are approved by the office to minimize erosion, conserve soil moisture, create and enhance wildlife habitat, or promote revegetation;

2. do not restrict normal access;

3. are not inappropriate substitutes for lower grades on the reclaimed lands.

D. All surface mining activities on slopes above 20 degrees, or on lesser slopes that the office defines as steep slopes, shall meet the provisions of Chapter 57.

E. All final grading, preparation of overburden before replacement of topsoil, and placement of topsoil shall be done along the contour to minimize subsequent erosion and instability. If such grading, preparation or placement along the contour is hazardous to equipment operators, then grading, preparation or placement in a direction other than generally parallel to the contour may be used. In all cases grading, preparation or placement shall be conducted in a manner which minimizes erosion and provides a surface for replacement of topsoil which will minimize slippage.

La. Admin. Code tit. 43, § XV-5407

Promulgated by the Department of Natural Resources, Office of Conservation, LR 5:395 (December 1979), amended LR 14:441 (July 1988), LR 20:447 (April 1994).

AUTHORITY NOTE: Promulgated in accordance with R.S. 30:901-932.