§ 816.71 - Disposal of excess spoil: General requirements.

§ 816.71 How must I dispose Disposal of excess spoil?: General requirements.

(a) General requirements. You, the permittee or operator, must mechanically transport and place excess spoil . Excess spoil shall be placed in designated disposal areas , including approved valley fills and other types of approved fills, within the permit area, in a controlled manner in compliance with the requirements of this section. In general, you must place excess spoil in a manner that will to -

(1) Minimize the adverse effects of leachate and surface water runoff from the fill on groundwater and surface water, including aquatic life, within the permit and adjacent areas. and ground waters;

(2) Ensure mass stability and prevent mass movement during and after construction. ; and

(3) Ensure that the final surface configuration of the fill is suitable for revegetation and the approved postmining land use or uses and is reclamation and revegetation compatible with the natural drainage pattern and surroundings .

(4) Minimize disturbances to,

and

adverse impacts on, fish, wildlife, and related environmental values to the extent possible, using the best technology currently available.

(5) Ensure that the fill will not change the size or frequency of peak flows from precipitation events or thaws in a way that would result in an increase in flooding when compared with the impacts of premining peak flows.

(6) Ensure that the fill will not cause or contribute to a violation of applicable state or tribal groundwater standards or preclude any premining use of groundwater.

(7) Ensure that the fill will not cause or contribute to a violation of applicable state or tribal water quality standards for surface water located downstream of the toe of the fill, including, but not limited to, water quality standards established under the authority of section 303(c) of the Clean Water Act, 33 U.S.C. 1313(c).

(b) Stability requirements -

(1) Static safety factor. You must design and construct the fill

the approved postmining land use.

(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 regulatory authority. 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.

(

2) Special requirement for steep-slope conditions.

c) Location. The disposal area shall be located on the most moderately sloping and naturally stable areas available, as approved by the regulatory authority, and shall be placed, where possible, upon or above a natural terrace, bench, or berm, if such placement provides additional stability and prevents mass movement.

(d) Foundation.

(1) Sufficient foundation investigations, as well as any necessary laboratory testing of foundation material, shall be performed in order to determine the design requirements for foundation stability. The analyses of foundation conditions shall take into consideration the effect of underground mine workings, if any, upon the stability of the fill and appurtenant structures.

(2) Where the slope in the disposal area

exceeds

is in excess of 2.8h:1v (36 percent), or

any

such lesser slope as may be designated by the regulatory authority based on local conditions,

you must construct bench

keyway cuts (excavations

into

to stable bedrock) or rock

-

toe buttresses shall be constructed to ensure

fill stability. (c) Compliance with permit. You must construct the fill in accordance with the design and plans approved in the permit

stability of the fill. Where the toe of the spoil rests on a downslope, stability analyses shall be performed in accordance with § 780.35(c) of this chapter to determine the size of rock toe buttresses and keyway cuts.

(

d

e)

Requirements for handling of organic matter and soil materials. You must remove all vegetation, other organic matter, and soil materials

Placement of excess spoil.

(1) All vegetative and organic materials shall be removed from the disposal area prior to placement of the excess spoil.

You must store, redistribute, or otherwise use those materials

Topsoil shall be removed, segregated and stored or redistributed in accordance with § 816.22

of this part. You may use soil substitutes and supplements if approved in the permit in accordance with § 780.12(e) of this chapter.

(e) Surface runoff control requirements.

(1) You must direct surface runoff from areas above the fill and runoff from the surface of the fill into stabilized channels designed to -

(i) Meet the requirements of § 816.43 of this part; and

(ii) Safely pass the runoff from the 100-year, 6-hour precipitation event. You must use the appropriate regional Natural Resources Conservation Service synthetic storm distribution to determine the peak flow from surface runoff from this event.

(2) You must grade the top surface of a completed fill such that the final slope after settlement will be toward properly designed drainage channels. You may not direct uncontrolled surface runoff over the outslope of the fill.

(f) Control of water within the footprint of the fill -

(1) General requirements. If the disposal area contains springs, natural or manmade water courses, or wet weather seeps, you must design and construct underdrains and temporary diversions as necessary to control erosion, prevent water infiltration into the fill, and ensure stability.

(2) Temporary diversions. Temporary diversions must comply with the requirements of § 816.43 of this part.

(3) Underdrains.

(i) You must construct underdrains that are comprised of hard rock that is resistant to weathering.

(ii) You must design and construct underdrains using current, prudent engineering practices and any design criteria established by the regulatory authority.

(iii) In constructing rock underdrains, you may use only hard rock that is resistant to weathering, such as well-cemented sandstone and massive limestone, and that is not acid-forming or toxic-forming. The underdrain must be free of soil and fine-grained, clastic rocks such as siltstone, shale, mudstone, and claystone. All rock used to construct underdrains must meet the criteria in the following table:

Test ASTM standard AASHTO standard Acceptable results Los Angeles AbrasionC 131 or C 535T 96Loss of no more than 50 percent of test sample by weight. Sulfate SoundnessC 88 or C 5240T 104Sodium sulfate test: Loss of no more than 12 percent of test sample by weight. Magnesium sulfate test: Loss of no more than 18 percent of test sample by weight.

(iv) The underdrain system must be designed and constructed to carry the maximum anticipated infiltration of water due to precipitation, snowmelt, and water from seeps and springs in the foundation of the disposal area away from the excess spoil fill.

(v) To provide a safety factor against future changes in local surface-water and groundwater hydrology, perforated pipe may be embedded within the rock underdrain to enhance the underdrain capacity to carry water in excess of the anticipated maximum infiltration away from the excess spoil fill. The pipe must be manufactured of materials that are not susceptible to corrosion and must be demonstrated to be suitable for the deep burial conditions commonly associated with excess spoil fill underdrains.

(vi) The underdrain system must be protected from material piping, clogging, and contamination by an adequate filter system designed and constructed using current, prudent engineering practices to ensure the long-term functioning of the underdrain system.

(g) Placement of excess spoil.

(1) Using mechanized equipment, you must transport and place excess spoil

. If approved by the regulatory authority, 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.

(2) 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;

and

graded so that surface and subsurface drainage is compatible with the natural surroundings

.

(2) You may not use any excess spoil transport and placement technique that involves end-dumping, wing-dumping, cast-blasting, gravity placement, or casting spoil downslope.

(3) Acid-forming, toxic-forming, and combustible materials.

(i) You must handle acid-forming and toxic-forming materials

; and covered with topsoil or substitute material in accordance with § 816.

38 of this part and in a manner that will minimize adverse effects on plant growth and the approved postmining land use.

(ii) You must cover combustible materials with noncombustible materials in a manner that will prevent sustained combustion and minimize adverse effects on plant growth and the approved postmining land use.

(h) Final configuration.

(1)

22 of this chapter. The regulatory authority 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.

(3) The final configuration of the fill

must

shall be suitable for the approved postmining land use

, compatible with the natural drainage pattern and the surrounding terrain, and, to the extent practicable, consistent with natural landforms. (2) You may construct terraces

. Terraces may be constructed on the outslope of the fill if required for stability,

to

control of erosion, to conserve soil moisture, or to facilitate the approved postmining land use. The grade of the outslope between terrace benches

may

shall not be steeper than 2h: 1v (50 percent).

(

3)

(i) You must configure the top surface of the fill to create a topography that includes ridgelines and valleys with varied hillslope configurations when practicable, compatible with stability and postmining land use considerations, and generally consistent with the topography of the area before any mining.

(ii) The final surface elevation of the fill may exceed the elevation of the surrounding terrain when necessary to minimize placement of excess spoil in perennial and intermittent streams, provided the final configuration complies with the requirements of paragraphs (a)(3) and (h)(1) of this section.

(iii) The geomorphic reclamation requirements of paragraph (h)(3)(i) of this section do not apply in situations in which they would result in burial of a greater length of perennial or intermittent streams than traditional fill design and construction techniques.

(i) Impoundments and depressions.

4) No permanent impoundments are allowed on the completed fill.

You may construct small depressions if they - (1) Are

Small depressions may be allowed by the regulatory authority if they are needed to retain moisture, minimize erosion, create

or

and enhance wildlife habitat, or assist revegetation;

(2) Are

and if they are not incompatible with the stability of the fill

;

.

(

3) Are consistent with the hydrologic reclamation plan approved in the permit in accordance with § 780.22 of this chapter;

(4) Will not result in elevated levels of parameters of concern in discharges from the fill; and

(5) Are approved by the regulatory authority.

(j) Surface area stabilization. You must provide slope protection

5) 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 and ground water in accordance with § 816.41, to prevent sustained combustion, and to minimize adverse effects on plant growth and the approved postmining land use.

(f) Drainage control.

(1) If the disposal area contains springs, natural or manmade water courses, or wet weather seeps, the fill design shall include diversions and underdrains as necessary to control erosion, prevent water infiltration into the fill, and ensure stability.

(2) Diversions shall comply with the requirements of § 816.43.

(3) Underdrains shall consist of durable rock or pipe, be designed and constructed using current, prudent engineering practices and meet any design criteria established by the regulatory authority. The underdrain system shall be designed to carry the anticipated seepage of water due to rainfall away from the excess spoil fill and from seeps and springs in the foundation of the disposal area and shall be protected from piping and contamination by an adequate filter. Rock underdrains shall be constructed of durable, nonacid-,nontoxic-forming rock (e.g., natural sand and gravel, sandstone, limestone, or other durable rock) that does not slake in water or degrade to soil material, and which is free of coal, clay or other nondurable material. Perforated pipe underdrains shall be corrosion resistant and shall have characteristics consistent with the long-term life of the fill.

(g) Surface area stabilization. Slope protection shall be provided to minimize surface erosion at the site.

You must revegetate all

All disturbed areas, including diversion channels that are not riprapped or otherwise protected, shall be revegetated upon completion of construction.

(

k

h)Inspections

and examinations

.

(1)

A qualified registered professional engineer, or other qualified professional specialist under the direction of the professional engineer,

must

shall periodically inspect the fill

at least quarterly

during construction

, with additional complete inspections conducted during critical construction periods

. The professional engineer or specialist

must

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

-

:

(i) Foundation preparation, including the removal of all organic

matter and soil materials.

material and topsoil;

(ii)

Placement

placement of underdrains and protective filter systems

.

;

(iii)

Installation

installation of final surface drainage systems

.

; and

(

2

iv)

An engineer or specialist meeting the qualifications of paragraph (k)(1) of this section also must -

(i) Conduct daily examinations during placement and compaction of fill materials or, when more than one lift is completed per day, upon completion of each 4-foot lift. As an alternative, the engineer or specialist may conduct examinations on a weekly basis if a mine representative takes photographs on a daily basis to document the lift thickness and elevation with visual reference features. The certified report required by paragraph (k)(3) of this section must include this photographic documentation.

(ii) Maintain a log recording the examinations conducted under paragraph (k)(2)(i) of this section for each 4-foot lift in each fill. The log must include a description of the specific work locations, excess spoil placement methods, compaction adequacy, lift thickness, suitability of fill material, special handling of acid-forming and toxic-forming materials, deviations from the approved permit, and remedial measures taken.

(3)

(i) The qualified registered professional engineer to which paragraph (k)(1) of this section refers must

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 regulatory authority

on a quarterly basis. (ii) In each report prepared under paragraph (k)(3)(i) of this section, the engineer must certify

promptly after each inspection that the fill has been constructed and maintained as designed and in accordance with the approved plan and this chapter.

(iii) The report prepared under paragraph (k)(3)(i) of this section must identify and discuss any evidence of

The report shall include appearances of instability, structural weakness,

or

and other hazardous conditions.

If one of more of those conditions exists, you must submit an application for a permit revision that includes appropriate remedial design specifications.

(

iv) The report prepared under paragraph (k)(

3)

(i)

of this section must contain -

(A) A review and summary of all complete inspections conducted during the quarter under paragraph (k)(1) of this section.

(B) A review and summary of all examinations conducted during the quarter under paragraph (k)(2) of this section, including the logs maintained under paragraph (k)(2)(ii) of this section.

(C)

The

photographs taken under paragraph (k)(2)(i) of this section. (v) Each certified report prepared under paragraph (k)(3) of this section for a quarter in which construction activities include placement of underdrains and protective filter systems must

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

must

shall be certified separately.

The photographs must

(ii) 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 § 816.73, color photographs shall be taken of the underdrain as the underdrain system is being formed.

(iii) 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)

You must retain a

A copy of each

certified report prepared under paragraph (k)(3) of this section

inspection report shall be retained at or near the mine site.

(

l

i)Coal mine waste.

You may dispose of coal mine waste

Coal mine waste may be disposed of in excess spoil fills

only

if approved by the regulatory authority and

only

, if such waste is -

(1)

You demonstrate, and the regulatory authority finds in writing, that the disposal of coal mine waste in the excess spoil fill will not -

(i) Cause or contribute to a violation of applicable state or tribal water quality standards or effluent limitations, including, but not limited to, water quality standards established under the authority of section 303(c) of the Clean Water Act, 33 U.S.C. 1313(c), and effluent limitations established in any National Pollutant Discharge Elimination System permit issued for the operation under section 402 of the Clean Water Act, 33 U.S.C. 1342, or its state or tribal counterpart;

(ii) Cause or contribute to a violation of applicable state or tribal water quality standards for groundwater; or

(iii) Result in material damage to the hydrologic balance outside the permit area.

(2) The waste is placed in accordance with §§ 816.81 and 816.83 of this part.

(3) The waste is nontoxic-forming, nonacid-forming, and non-combustible.

(4) The waste is of

Placed in accordance with § 816.83;

(2) Nontoxic and nonacid forming; and

(3) Of the proper characteristics to be consistent with the design stability of the fill.

(

m

j)Underground disposal.

You

Excess spoil may

dispose

be disposed of

excess spoil

in underground mine workings, but only in accordance with a plan approved by the regulatory authority and

the Mine Safety and Health Administration

MSHA under § 784.

26

25 of this chapter.

[48 FR 32925, July 19, 1983, as amended at 48 FR 44780, Sept. 30, 1983; 73 FR 75883, Dec. 12, 2008; 79 FR 76231, Dec. 22, 2014; 81 FR 93392, Dec. 20, 2016; 82 FR 54979, Nov. 17, 2017]