La. Admin. Code tit. 43 § XV-5365

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

Section XV-5365 - Disposal of Excess Spoil: General Requirements

A. Spoil not required to achieve the approximate original contour within the area where overburden has been removed shall be hauled, or conveyed to, and placed in designated disposal areas within a permit area, if the disposal areas are authorized for such purposes in the approved permit application in accordance with §5365-5371 The spoil shall be placed in a controlled manner to ensure:

1. that leachate and surface runoff from the fill will not degrade surface water or ground water or exceed the effluent limitations of §5321;

2. stability of the fill; and

3. that the land mass designated as the disposal area is suitable for reclamation and revegetation compatible with the natural surroundings.

B. Design Certification

1. The fill and appurtenant structures shall be designed using current, prudent engineering practices and shall meet any design criteria established by the office. A qualified registered professional engineer experienced in the design of earth and rock fills shall certify the design of the fill and appurtenant structures.

2. The fill shall be designed to attain a minimum long-term static safety factor of 1.5. The foundation and abutments of the fill must be stable under all conditions of construction.

C. All vegetative and organic material shall be removed from the disposal area and the topsoil shall be removed, segregated and stored or replaced under §5309-5317 If approved by the office, organic material may be used as mulch or may be included in the topsoil to control erosion, promote growth of vegetation, or increase the moisture retention of the soil.

D. Slope protection shall be provided to minimize surface erosion at the site. Diversion design shall conform with the requirements of §5323 All disturbed areas, including diversion ditches that are not riprapped, shall be vegetated upon completion of construction.

E. The disposal areas shall be located on the most moderately sloping and naturally stable areas available as approved by the office. If such placement provides additional stability and prevents mass movement, fill materials suitable for disposal shall be placed upon or above a natural terrace, bench or berm.

F. Excess spoil shall be transported and placed in a controlled manner in horizontal lifts not exceeding 4 feet in thickness; concurrently compacted as necessary to ensure mass stability and to prevent mass movement during and after construction; graded so that surface and subsurface drainage is compatible with the natural surroundings; and covered with topsoil or substitute material in accordance with §5311 The office may approve a design which incorporates placement of excess spoil in horizontal lifts other than 4 feet in thickness when it is demonstrated by the operator and certified by a qualified registered professional engineer that the design will ensure the stability of the fill and will meet all other applicable requirements.

G. The final configuration of the fill must be suitable for post-mining land uses approved in accordance with §5431, except that no depressions or impoundments shall be allowed on the completed fill.

H. Terraces may be utilized to control erosion and enhance stability if approved by the office and consistent with §5407. B The grade of the outslope between terrace benches shall not be steeper than 1v:2h (50 percent).

I. Excess spoil that is acid- or toxic-forming or combustible shall be adequately covered with nonacid, nontoxic and noncombustible material, or treated, to control the impact on surface water and ground water in accordance with §5319, to prevent sustained combustion, and to minimize adverse effects on plant growth and the approved post-mining land use.

J. Where the slope in the disposal area exceeds 1v:2.8h (36 percent), or such lesser slope as may be designated by the office based on local conditions, key way cuts (excavations to stable bedrock) or rock toe buttresses shall be constructed to stabilize the fill. Where the toe of the spoil rests on a downslope, stability analyses shall be performed in accordance with §2735. C to determine the size of rock-toe buttresses and key-way cuts.

K. Inspections. A qualified registered professional engineer, or other qualified professional specialist under the direction of the professional engineer, shall periodically inspect the fill during construction. The professional engineer or specialist shall be experienced in the construction of earth and rock fills.

1. Such inspections shall be made at least quarterly throughout construction and during critical construction periods. Critical construction periods shall include at a minimum:

a. foundation preparation, including the removal of all organic material and topsoil;

b. placement of underdrains and protective filter systems;

c. installation of final surface drainage systems; and

d. the final graded and revegetated fill. Regular inspections by the engineer or specialist shall also be conducted during placement and compaction of fill materials.

2. The qualified registered professional engineer shall provide a certified report to the office promptly after each inspection that the fill has been constructed and maintained as designed and in accordance with the approved plan and this Section. The report shall include appearances of instability, structural weakness and other hazardous conditions.

3.

a. The certified report on the drainage system and protective filters shall include color photographs taken during and after construction, but before underdrains are covered with excess spoil. If the underdrain system is constructed in phases, each phase shall be certified separately.

b. Where excess durable rock spoil is placed in single or multiple lifts such that the underdrain system is constructed simultaneously with excess spoil placement by the natural segregation of dumped materials, in accordance with §5371, color photographs shall be taken of the underdrain as the underdrain system is being formed.

c. The photographs accompanying each certified report shall be taken in adequate size and number with enough terrain or other physical features of the site shown to provide a relative scale to the photographs and to specifically and clearly identify the site.

4. A copy of each inspection report shall be retained at or near the mine site.

L. Coal processing wastes shall not be disposed of in head-of-hollow or valley fills, and may only be disposed of in other excess spoil fills, if such waste is:

1. placed in accordance with §5381;

2. demonstrated to be non-toxic- and non-acid-forming; and

3. demonstrated to be consistent with the design stability of the fill.

M. If the disposal area contains springs, natural or man-made watercourses or wet weather seeps, an underdrain system consisting of durable non-acid-, non-toxic-forming rock that does not slake in water or degrade to soil material, and which is free of coal, clay or other nondurable material shall be constructed from the wet areas in a manner that prevents infiltration of the water into the spoil material. The underdrain system shall be protected by an adequate filter and shall be designed and constructed using standard geotechnical engineering methods.

N. The foundation and abutments of the fill shall be stable under all conditions of construction and operation. Sufficient foundation investigation and laboratory testing of foundation materials shall be performed in order to determine the design requirements for stability of the foundation.

La. Admin. Code tit. 43, § XV-5365

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.