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EPA 821-R-00-008
DEVELOPMENT DOCUMENT
FOR PROPOSED EFFLUENT LIMITATIONS
GUIDELINES AND STANDARDS FOR THE
WESTERN ALKALINE COAL MINING SUBCATEGORY
March 2000
Office of Water
Office of Science and Technology
Engineering and Analysis Division
U.S. Environmental Protection Agency
Washington, DC 20460
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Acknowledgments
This document was developed under the direction of William A. Telliard of the
Engineering and Analysis Division (BAD) within the U.S. Environmental Protection Agency's
(EPA) Office of Science and Technology (OST). This manual was made possible through the
efforts of a Western Coal Mining Work Group (WCMWG) consisting of representatives from the
Office of Surface Mining Reclamation and Enforcement (OSMRE), the Western Interstate
Energy Board (WIEB), the National Mining Association (NMA), industry, and consulting firms.
EPA gratefully acknowledges the contributions of the WCMWG for the preparation and
submittal of technical information packages, reports, and performance in support of the proposed
. rulemaking. EPA also wishes to thank DynCorp Information and Enterprise Technology for its
invaluable support.
The primary contact regarding questions or comments on this document is:
William A. Telliard
Engineering and Analysis Division (4303)
U.S. Environmental Protection Agency
Ariel Rios Building, 1200 Pennsylvania Avenue
Washington, DC 20460
Phone: 202/260-7134
Fax: 202/260-7185
email: telliard.william@epamail.epa.gov
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Table of Contents
Acknowledgments z
Table of Contents Mi-
List of Figures , vii
List of Tables ix
Acronyms xi
Glossary xm
Executive Summary xix
1.0 BACKGROUND
1.1 Legal Authority 1-1
1.2 Regulatory History 1-1
1.2.1 Clean Water Act 1-4
1.2.2 Surface Mining Control and Reclamation Act 1-6
1.2.3 State Regulatory Guidelines for Sediment Control '. 1-11
2.0 INDUSTRY CHARACTERIZATION
2.1 Location and Production 2-1
2.2 Environmental Conditions 2-6
2.2.1 Temperature 2-6
2.2.2 Precipitation 2-6
2.2.3 Erosion Prone Soils 2-8
2.2.4 Hydrology and Sedimentation 2-8
2.2.5 Vegetation 2-10
2.2.6 Watershed Runoff Characteristics 2-10
2.2.7 Cumulative Effect 2-11
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3.0 BEST MANAGEMENT PRACTICES
3.1 Sediment 3-1
3.2 Sedimentation Pond Use and Impacts in Arid and Semiarid Regions 3-1
3.2.1 Surface Disturbance 3-2
3.2.2 Water Impoundment 3-3
3.2.3 Sediment Retention 3-6
3.2.4 Scouring and Seeps 3-6
3.3 Sediment Control BMPs 3-8
3.3.1 Managerial BMPs 3-9
3.3.2 Structural BMPs 3-10
3.3.3 BMP Implementation 3-13
3.4 Prediction Models for BMP Design and Implementation 3-19
3.4.1 RUSLE 3-20
3.4.2 SEDCAD 3-22
3.4.3 SEDIMOTH 3-23
3.4.4 HEC-6 3-23
3.4.5 MULTSED 3-24
4.0 BENEFITS OF SEDIMENT CONTROL BMPS
4.1 Environmental Benefits 4-1
4.1.1 Source Control 4-1
4.1.2 Minimizes Disturbance to the Hydrologic Balance 4-2
4.1.3 Maintains Natural Sediment Yield 4-3
4.1.4 Minimizes Surface Disturbance 4-4
4.1.5 Encourages Vegetation 4-5
4.1.6 Improves Soil and Promotes Soil Conservation 4-5
4.1.7 Addresses Site-Specific Environmental Conditions 4-6
4.1.8 Stabilizes Landforms 4-6
4.1.9 Minimizes Disruptions to Flow Regime 4-7
4.2 Implementation and Enforcement Benefits 4-7
4.2.1 Implements Existing Requirements 4-7
4.2.2 Improves Monitoring and Inspection Capability 4-8
4.2.3 Provides Control and Treatment Flexibility 4-9
IV
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5.0 CASE STUDIES
5.1 Case Study 1 (Western Coal Mining Work Group, 1999c) 5-1
5.1.1 Modeling Results 5-3
5.1.2 Cost 5-6
5.2 Case Study 2 (Bridger Coal Company, Jim Bridger Mine) 5-10
5.2.1 Justification of ASC's 5-10
5.2.2 Description of ASC Techniques 5-12
5.2.3 ASC Design 5-13
5.2.4 Monitoring Program 5-17
5.2.5 Data Reduction , 5-18
5.2.6 Data Analysis 5-19
5.2.7 Summary 5-26
5.3 Case Study 3 (Water Engineering and Technology, Inc., 1990) 5-27
5.3.1 Background Sediment Yield 5-28
5.3.2 Evaluation of Watershed Computer Models 5-31
5.3.3 Rainfall Simulation Data Collection 5-33
5.3.4 Calibration and Validation of the MULTSED Model 5-43
5.3.5 Evaluation of Alternative Sediment Control Techniques 5-43
6.0 REFERENCES , 6-1
APPENDIX A:
APPENDIX B:
APPENDIX C:
APPENDIX D:
Wyoming Coal Rules and Regulations, Chapter IV
Wyoming Guideline No. 15
19 NMAC 8.2 Subpart 20 Section 2009
Mine Modeling and Performance Analysis - Model Input and Output
Data
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List of Figures
SECTION 1.0
Figure la: Timeline of Selected Mining Regulations Affecting the
Coal Mining Industry 1-3
SECTION 2.0
Figure 2a: Coal Producing Areas 2-2
SECTION 5.0
Figure 5a: Mine Model Approach: A Method for Evaluating Erosion
and Sediment Control Options 5-4
Figure 5b: Initial Receiving Stream TSS Data 5-11
Figure 5c: Sediment Yield vs. Water Yield 5-25
Figure 5d: Navajo Mine Sediment Yield vs. Plot Slope 5-45
Figure 5e: Navajo Mine Sediment Yield vs. Percent Ground Cover 5-45
Figure 5f: Navajo Mine Sediment Yield vs. Slope Length „ 5-46
Figure 5g: Navajo Mine Sediment Yield vs. Depression Storage 5-46
Figure 5h: McKinley Mine Sediment Yield vs. Plot Slope 5-47
Figure 5i: McKinley Mine Sediment Yield vs. Plot Slope 5-47
Figure 5j: McKinley Mine Sediment Yield vs. Slope Length 5-48
Figure 5k: McKinley Mine Sediment Yield vs. Percent Ground Cover 5-48
Figure 51: McKinley Mine Sediment Yield vs. Depression Storage 5-49
Figure 5m: Black Mesa/Kayenta Mines Sediment Yield vs. Plot Slope 5-49
Figure 5n: Black Mesa/Kayenta Mines Sediment Yield vs. Plot Slope 5-50
Figure So: Black Mesa/Kayenta Mines Sediment Yield vs. Slope Length ;. 5-50
Figure 5p: Black Mesa Mine Sediment Yield vs. Slope Length 5-51
Figure 5q: Black Mesa/Kayenta Mines Sediment Yield vs. Percent
Ground Cover : 5-51
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List of Tables
SECTION 2.0
Table 2a: United States Coal Production by Region (short tons) 2-3
Table 2b: Operation and Production Statistic of Potentially Affected Coal
Mines in the Arid and Semiarid Coal Producing Region 2-4
Table 2c: Average Annual Precipitation in Arid and Semiarid Coal States 2-7
SECTION 3.0
Table 3a: Area Disturbance and Watershed Drainage of Sedimentation Ponds
at Four Western Mine Operations 3-3
Table 3b: Examples of Managerial Sediment and Erosion Control Practices 3-10
Table 3c: Examples of Structural Best Management Practices 3-11
SECTION 5.0
Table 5a: Representative Mine Characteristics and Model Input Information.. 5-2
Table 5b: Comparison of Hydrology and Sedimentology Results 5-8
Table 5c: Cost of Existing Guideline Compliance vs. Cost to Implement
Alternative Sediment Control BMPs 5-9
Table 5d: Premining Surface Water Quality 5-13
Table 5e: Existing Database, Undisturbed TSS Concentration Data 5-16
Table 5f: Order of Simulation of Sediment Control Best Management
Practices 5-17
Table 5g: Example Water and Sediment Yield Data (1984-1998) 5-20
Table 5h: Measured Sediment Yields at Navajo and McKinley Coal Mines 5-29
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Table 5i: Ranking of Five Computer Models 5-32
Table 5j: Rainfall, Runoff and Sediment Yield Data for Navajo Mine 5-34
Table 5k: Rainfall, Runoff and Sediment Yield Data for McKinley Mine 5-37
Table 51: Rainfall, Runoff and Sediment Yield Data for Black Mesa and
Kayenta Mines 5-40
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Acronyms
acre-ft: acre-feet
ASCM: Alternative Sediment Control Measure
BAT: Best Available Technology
BMP: Best Management Practice
BPT: Best Practicable Control Technology Currently Available
BTCA: Best Technology Currently Available
Btu: British thermal unit
cfs: cubic feet per second
CHIA: Cumulative Hydrologic Impact Assessment
CWA: Federal Water Pollution Control Act of 1972; the Clean Water Act
DEQ: Department of Environmental Quality
EASI: Erosion and Sediment Impacts Model
EPA: U.S. Environmental Protection Agency
FEIS: Final Environmental Impact Statement
LQD: Land Quality Division
mg/L: milligrams per liter
ml/L: milliliters per liter
MMD: New Mexico Mining and Minerals Division
MUSLE: Modified Universal Soil Loss Equation
NMA: National Mining Association
NOV: Notice of Violation
NPDES: National Pollution Discharge Elimination System
NRCS: Natural Resource Conservation Service
NSPS: New Source Performance Standard
OSMRE: Office of Surface Mining and Reclamation Enforcement
PHC: Probable Hydrologic Consequence
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RUSLE: Revised Universal Soil Loss Equation
SCS: Soil Conservation Service
SEDCAD: Sediment, Erosion, Discharge by Computer Aided Design
SEDIMOTII: Sedimentology by Distributed Model Treatment
SMCRA: Surface Mining Control and Reclamation Act
SS: Settleable Solids
TSS: Total Suspended Solids
DOT: Department of Transportation
USDA: United States Department of Agriculture
USLE: Universal Soil Loss Equation
WIEB: Western Interstate Energy Board
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Glossary
Alkaline Mine Drainage: Mine drainage which, before any treatment, has a pH equal to or
greater than 6.0 and a total iron concentration of less than 10 mg/L.
Approximate Original Contour: Surface configuration achieved by backfilling and grading of
mined areas so that the reclaimed land surface closely resembles the general surface
configuration of the land prior to mining and blends into and complements the drainage
pattern of the surrounding terrain.
Arid and semiarid area: An area of the interior western United States, west of the 100th
meridian west longitude, experiencing water deficits, where water use by native
vegetation equals or exceeds that supplied by precipitation. All coalfields located in
North Dakota west of the 100th meridian west longitude, all coal fields in Montana,
Wyoming, Utah, Colorado, New Mexico, Idaho, Nevada, and Arizona, The Eagle Pass
field in Texas, and the Stone Canyon and the lone fields in California are in arid and
semiarid areas (30 CFR Ch. VE § 701.5).
Armoring: Lining drainage channels with rock to limit re-transport of the channel bottom.
Arroyo: A term applied in the arid and semiarid regions of southwest United States to the small
deep flat-floored channel or gully of an ephemeral stream or an intermittent stream,
usually with vertical or steeply cut banks of unconsolidated material at least 60 cm high.
It is usually dry, but may be transformed into a temporary water-course or short lived
torrent after heavy rainfall (Bates and Jackson, 1980).
Bank Carving: A form of erosion in which the foundation of the banks of a stream or river are
undermined due to an increase in flow rate causing the bank to fail.
Bank Slumping: See bank carving.
Berming: An engineering technique which creates a long mound of earth to control the flow of
water.
Best Management Practice: Schedules of activities, prohibitions or practices, maintenance
procedures, and other management or operational practices to prevent or reduce the
pollution of waters of the United States.
British Thermal Unit: The amount of heat needed to raise the temperature of 1 pound of water
by 1 degree Fahrenheit, approximately equal to 252 calories. The Btu is a convenient
measure by which to compare the energy content of various fuels.
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Channel Head: The upper reaches of a stream where the kinetic energy of water is highest.
Channel Head-Cutting: Loss of sediment from the upper reaches of a stream.
Channel Bed: The sediment at the deepest portion of a stream.
Coal Surface Mine: A coal-producing mine that extracts coal that is usually within a few
hundred feet of the surface. Earth and rock above the coal (overburden) is removed to
expose the coal seam which is then excavated with draglines, bulldozers, front-end
loaders, augering and/or other heavy equipment. It may also be known as an area,
contour, open-pit, strip, or auger mine.
Concentration of Contaminant: The amount of pollutant parameter proportional to the total
volume.
Contour Furrowing: A soil-loss prevention technique adapted to control sediment runoff. The
sediment is plowed along the contour lines which helps impede water flow.
Disturbed Area: An area which has been altered in generally an unacceptable manner by human
or natural actions.
Diverting Runoff: An engineering technique to force water away from natural watercourses,
allowing for reduction in water velocity and volume.
Dry wash: A wash (stream or gully) that carries water only at infrequent intervals and for brief
periods, as after a heavy rainfall.
Ephemeral Stream: A stream which flows only in direct response to precipitation in
the immediate watershed or in response to snow melt, and which has a channel bottom
that is always above the prevailing water table.
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Erosion: A natural process by the action of water, wind, and ice in which soil and rock material
is loosened and removed. The major factors affecting soil erosion are soil characteristics,
climate, rainfall intensity and duration, vegetation or other surface cover, and topography.
Evapotranspiration: That portion of precipitation returned to the air through direct evaporation
or by transpiration of vegetation.
Ferruginous: Of coals, minerals and rocks containing iron. Water running off such materials is
usually rust colored, and will tend to be acidic.
Flash Flooding: A large surge of water runoff from a storm event. Flash floods are worsened
by lack of vegetation or natural flow-retarding elements such as soils, lakes or
impoundments.
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Flow Naturally: The course of water unimpeded or altered by man-made activity or structures.
Fluvial: Relating to, or occurring in a river.
Fluvial Processes: The physical actions of water on sediments, changing and being changed by
the results of those actions.
Fluvial Morphology: Landforms and structures created by the activity of water both in motion
and at rest.
Forb: A broad-leaved herbaceous plant, as distinguished from grasses, shrubs and trees.
Geotextiles: Porous fabrics composed of woven synthetic materials. Geotextiles also are known
as filter fabrics, road rugs, synthetic fabrics, constructions, or geosynthetic fabrics.
Grading: Cutting and/or filling land surfaces with heavy equipment to create a desired
configuration, slope or elevation.
Grass Filter Strips: Sections of land with planted grass to help retain eroding sediment.
Harvested Precipitation: The rainfall that is channeled by gutters or ditches to a storage area or
for an immediate specific use.
Head-cut Erosion: The sudden change in elevation or knickpoint at the leading edge of a gully.
Head-cuts can range from less than an inch to several feet in height, depending on several
factors. The formation and movement of a gully head-cut are often the dominant form of
damage observed in an earth spillway.
High-Yield Storm: A rain storm with a large amount of impact.
Hydrophitic Vegetation: Water-loving vegetation requiring considerable water to survive.
Hydrologic Balance: The relationship between the quality and quantity of water inflow to,
outflow from, and storage in a hydrologic unit such as a drainage basin, aquifer, soil zone,
lake or reservoir. A water budget that encompasses the dynamic relationships among
precipitation, surface runoff, evaporation, and changes in surface water and ground water
storage.
Infiltration: Surface water sinking into the sediment column as the first step towards becoming
ground water.
Irrigation: Application of water to agricultural or recreational land for promoting plant growth.
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Kinetic Energy: Energy contained by mass in motion. In particular, rapidly moving water will
have relatively high kinetic energy, allowing for the movement of large amounts of
sediment (see turbulent flow).
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Mass wasting: The movement of regolith downslope by gravity without the aid of a transporting
medium. Mass wasting depends on the interaction of soils, rock particles and moisture
content. \
t
Morphology: The form and structure of the landscape, i.e., slope, errosional features, hills, etc.
i
Mulch: A temporary soil stabilization or erosion control practice where materials such as grass,
hay, woodchips, wood fibers, or straw are placed on the soil surface. A natural or
artificial layer of plant residue or other materials covering the land surface that conserves
moisture, holds soil in place, aids in establishing plant cover, and minimizes temperature
fluctuations.
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Non-consumptive retention: The impoundment of water without its extraction for other uses.
Perennial Rivers: Rivers which flow during particular seasons in a predictable manner.
Periodic Releases: An infrequent discharge of water either by design or by naturally intermittent
precipitation.
Precipitation: The discharge of water, in liquid or solid state, from the atmosphere, generally
onto a land or water surface. The term "precipitation" is also commonly used to designate
the quantity of water that is precipitated. Forms of precipitation include drizzle, rainfall,
glaze, sleet, snow, and hail. !
Receiving Stream: A down-gradient stream that catches runoff from a mining area.
Reclaimed Area: A disturbed area that is restored by remediation activities to an acceptable
condition.
Reclamation Area: The surface area of a coal mine that has been returned to required contour
and on which revegetation (specifically seeding or planting) work has commenced.
Regolith: The layer or loose unconsolidated rock material, including soil, resting on bedrock,
constituting the surface of most land.
Rill Erosion: Rill erosion is the removal of soil by concentrated water running through little
streamlets, or head-cuts.
Riparian Habitat: Areas adjacent to rivers and streams that have a high density, diversity, and
productivity of plant and animal species relative to nearby uplands.
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Runoff: That part of precipitation, snow melt, or irrigation water that runs off the land into
streams or other surface waterbody.
Runoff Event: In arid and semiarid areas, the majority of the annual precipitation occurs during
infrequent rainfalls causing surface water runoff events that result in most of the erosion.
Scouring: The clearing and digging action of flowing water, especially the downward erosion
caused by stream water in sweeping away mud and silt from the stream bed and outside
bank of a curved channel.
Sediment: Soil and rock particles washed from land into waterbodies, usually after significant
rain. For the purpose of this document, sediment is all material transported by surface
water drainage, including total settleable solids, suspended solids, and bedload.
Sediment Control Measures: Engineering and biological techniques and practices to control the
quantity and location of sedimentation.
Sediment Imbalance: An abnormally high increase or decrease in sedimentation rates caused by
some activity.
Sediment Yield: the sum of the soil losses minus deposition in macro-topographic depressions,
at the toe of the hillslope, along field boundaries, or in terraces and channels sculpted into
the hillslope.
Sedimentation: The process of depositing soil particles, clays, sand, or other sediments
transported by flowing water.
Sedimentation Pond: A sediment control structure designed, constructed, and maintained to
slow down or impound precipitation runoff that allows the water to drop its sediment load
and reduce sediment concentrations at the point source discharge.
Seep: A point where water oozes or flows from the earth.
Semiarid: Landscape characterized by scanty rainfall. Pertaining to a subdivision of climate in
which the associated ecological conditions are distinguished by short grass and scrubby
vegetation.
Sheet Erosion: The detachment of land surface material by raindrop impact and thawing of
frozen grounds and its subsequent removal by overland flow.
Sodic: Pertaining to or containing sodium: sodic soil.
Soil Erodibility Factor: The inability of a soil to resist erosive energy of rains A measure of the
erosion potential for a specific soil type based on inherent physical properties such as
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particle size, organic matter, aggregate stability, and permeability.
Soil Loss: that material actually removed from the particular hillslope or hillslope segment. The
soil loss may be less than erosion due to on-site deposition in microtopographic
depressions on the hillslope.
Steepness Factor: Combination factor of for slope length and gradient.
Terrace Levels: Sediment platforms within stream channels, where different volumes of water
periodically flow.
Turbulent Flow: Chaotic water movement with high kinetic energy which allows for fast
sediment erosion and sediment high carrying capacity.
Underfit: A small water flow eroding a sub-channel within a large currently dry stream channel.
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Vegetation Encroachment: Abnormal vegetative growth which impedes the natural flow of a
water course.
Volume of Flow: A measure of the quantitu of water moving per unit of time.
Water-monitoring Program: A sampling of water at designated locations and times to
characterize how its qualitites and quantities change over space and time.
Watershed: An area contained within a drainage divide above a specified point on a stream.
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Executive Summary
Purpose
This document supports the United States Environmental Protection Agency's (EPA's)
proposal of a new Western Alkaline Coal Mining Subcategory under existing regulations at 40
. CFR part 434 for the Coal Mining industry. The document was developed primarilyvusing
information supplied by a Western Coal Mining Work Group consisting of representatives from
federal and state regulatory agencies and industry. The purpose of this document is to provide a
summary of the information collected and used by EPA to support proposal of this Subcategory
and to develop the requirements under the proposed rule.
Western Alkaline Coal Mining Subcategory
The Western Alkaline Coal Mining Subcategory is a new Subcategory being proposed for
the coal mining industry to address sedimentation and erosion control issues that are
characteristic to the arid and semiarid coal producing regions of the western United States. EPA
finds that the use of additional or alternative sediment control best management practices (BMP)
in reclamation areas within these regions is less harmful to the environment than the impacts
resulting from compliance with existing sedimentation pond-based effluent limits. EPA believes
that controlling sediment generation at the source with the implementation of BMPs will reduce
erosion and sedimentation. EPA also believes that the implementation of appropriate BMPs in
these regions can prevent the formation of unnatural geomorphic land and stream forms, and will
improve water management, vegetation, and land uses.
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The objective of this rulemaking effort is to add a Western Alkaline Coal Mining
subcategory to 40 CFR part 434 for coal mining operations conducted in arid and semiarid
regions in the western United States. Only mining and reclamation operations producing alkaline
mine drainage on lands west of the 100th meridian west longitude, and receiving an average
annual precipitation of 26.0 inches or less would be applicable under the proposed subcategory.
Presumptive Rulemaking
Proposal of the Western Alkaline Coal Mining Subcategory is a presumptive rulemaking
effort implementing recommendations of EPA's Effluent Guidelines Task Force for streamlining
the regulations development process and expediting promulgation of effluent limitations
guidelines (May 28, 1998, 63 FR 29203). Under these recommendations, this rulemaking effort
relies on stakeholder support for various stages of information gathering; utilizes existing
information; focuses on an industry segment for which controls have been identified that would
result in environmental improvements; and is based on early presumptions regarding effective
control technologies and key pollutant parameters. Development of this proposed subcategory
relies on existing technical and economic information compiled from demonstrated successful
state approaches, federal regulatory requirements, and regulated community partnerships.
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Section 1.0 Background
1.1 Legal Authority
EPA is proposing the Western Alkaline Coal Mining Subcategory under the authority of
Sections 301, 304, 306, 307, 308, and 501 of the Federal Water Pollution Control Act (Clean
Water Act; CWA). EPA is proposing this Subcategory also under Section 304(m) of the Clean
Water Act which requires EPA to publish a biennial Effluent Guidelines Plan, set a schedule for
review and revision of existing regulations and identify categories of dischargers to be covered
by new regulations.
EPA's legal authority to promulgate BMP regulations is found in Section 304(e), Section
307(b) and (c), Section 308(a), Section 402(a)(l)(B), Section 402(a)(2) and Section 501(a) of the
Clean Water Act, 33 U.S.C. § 1251, et. seq. EPA's legal authority also relies on 40 CFR part
122.44(k). This BMP regulation is consistent with the Pollution Prevention Act of 1990,42
U.S.C. § 13101, et. seq.
This subcategory is being proposed in response to the consent decree in NRDC et. al. v.
Browner (D.D.C. Civ. No. 89-2980, January 31, 1992, as modified) which commits EPA to
schedules for proposing and taking final action on effluent limitations guidelines. The consent
decree publication date for proposal of revised effluent limitations guidelines for the coal mining
industry were published on May 28, 1998 at 63 FR 29203.
1.2 Regulatory History
The coal mining industry in the United States has a history covering over two centuries
with no particular consideration given to its effect on the environment until recently. During the
last thirty years, the proliferation of federal environmental laws has altered the coal mining
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industry (Figure la). Environmental impact considerations are now commonly woven into most
government and industry decision-making. Laws such as the Surface Mining Control and
Reclamation Act (SMCRA) and the Clean Water Act (CWA) reflect a strong current of public
opinion favoring preservation of resources and protection of fragile and life-supporting
ecosystems. EPA is charged with administering most federal environmental laws, but EPA may
delegate authority to states and tribal organizations that develop their own environmental
protection agencies to enforce the minimum federal standards or, depending on the location,
more stringent state or tribal standards.
Coal mine operators are issued a surface mining permit under SMCRA and a National
Pollutant Discharge Elimination System (NPDES) permit under CWA. .Allowable pollutant
discharge levels are usually determined by EPA's technology-based standards, or are based on
more stringent water quality standards. NPDES permits on surface mines usually require
monitoring of pH, total suspended solids, total iron, and total manganese. The regulatory
authority responsible for a particular mining situation may require monitoring of other
parameters.
1-2
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Figure la: Time line of Selected Mining Regulations Affecting the Coal Mining Industry
(modified from EIA, 1995)
Mechanical stokers introduced
Coal-mining machines brought into use
United Mine Workers of America formed (1890)
Machine developed to undercut coaibeds
5,000-kilowatt steam turbine introduced to generate electricity
Coal mined with steam-powered stripping shovel
Short-flame or. "permissible" explosives developed
Pulverized coal-firing in electric powerplants
Mechanical coal-loading machine introduced
Dragline excavators built especially for surface coal mining
Walking dragline excavators developed
Auger surface mining introduced
1880
1890
World War I, increased demand for coal
All-time high employment of 179,679
anthracite miners (1914)
Anthracite production peak of 99.6 million tons (1917)
Continuous underground mining systems developed
Roof bolting introduced in underground mines^
Longwall mining with powered roof supports
1950
1960
Federal Mineral Leasing Act of 1920
All-time high employment of 704,793
bituminous coal and lignite miners (1923)
World War II: Coal production increase for the war effort
and the postwar Marshall Plan
Railroads converting from coal to diesel fuel
Unit coal trains introduced by railroads
Final guidelines promulgated
at40CFRpart434^
Revised effluent limitations guidelines _
promulgated at 40CFR part 434,
1970
1980
1990
Federal Clean Water Act of 1972
Federal Coal Mine Health and Safety Act of 1969
Federal Clean Air Act of 1970
Federal Water Pollution Control Act of 1972
Arab Oil Embargo; coal production and prices rise
Federal Coal Leasing Amendments Act of 1976
Federal Surface Mine Control and Reclamation Act of 1977
^Federal Clean Water Act Amendments of 1977
Federal Clean Air Act Amendments of 1990
I Coaf Production in excess of 1 billion tons
''Federal Energy Policy Act of 1992
Background
1-3
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
This section presents a summary of SMCRA and CWA regulations affecting the coal mining
i
industry and, in particular, sedimentation requirements in the arid and semiarid western coal
mining region. This section also describes selected state programs that deal successfully with
sedimentation issues of coal mines in arid and semiarid regions.
1.2.1 Clean Water Act
•
i
The Clean Water Act of 1972 and the Clean Water Act Amendments of 1977 established
a comprehensive program to "restore and maintain the chemical, physical, and biological
integrity of the Nation's waters." To implement the program, EPA was charged with issuing
effluent limitation guidelines standards, pretreatment standards, and new source performance
standards (NSPS) for industrial discharges. These regulations were to be based principally on the
degree of effluent reduction attainable through the application of control technologies.
On October 17, 1975 (40 PR 48830), EPA proposed regulations adding part 434 to Title
40 of the Code of Federal Regulations. These regulations, with subsequent amendments,
established effluent limitations guidelines for coal mine operations based on the use of the "best
practicable control technology currently available" (BPT) for existing sources in the coal mining
point source category. These regulations were followed on April 26, 1977 (42 FR 21380) by
final BPT effluent limitations guidelines for the coal mining point source category. BPT
guidelines were established for total suspended solids, pH, total iron, and/or total manganese for
three subcategories: Acid Mine Drainage, Alkaline Mine Drainage, and Coal Preparation Plants
and Associated Areas. At that time the guidelines did not apply to discharges from reclamation
areas, nor did TSS limitations apply to any discharges from coal mines located in Colorado,
Montana, North Dakota, South Dakota, Utah, and Wyoming.
On October 9, 1985 (50 FR 41296), EPA promulgated the revised effluent limitations
guidelines and standards that are in effect to date under 40 CFR part 434. Currently, there are
four subcategories: Coal Preparation Plants and Coal Preparation Plant Associated Areas, Acid
or Ferruginous Mine Drainage, Alkaline Mine Drainage, and Post-Mining Areas, along with a
1-4 Background
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
subpart for Miscellaneous Provisions with BPT, BAT, and NSPS limitations for TSS, pH, total
iron, total manganese, and settleable solids (SS). Specifically, effluent limitations for discharges
from reclamation areas include SS and pH at 0.5 ml/L and 6 to 9 standard units, respectively.
On October 18, 1997, Vice President Gore called for a renewed effort to restore and
protect water quality. EPA and other federal agencies were directed to develop a Clean Water
Action Plan that addressed three major goals: (1) enhanced protection from public health threats
caused by water pollution; (2) more effective control of polluted runoff; and (3) promotion of
water quality protection on a watershed basis. The Clean Water Action Plan was to be based on
three principles:
» Develop cooperative approaches that promote coordination and reduce duplication
among federal, state, and local agencies and tribal governments wherever
possible;
• Maximize the participation of community groups and the public, placing
particular emphasis on ensuring community and public access to information
about water quality issues; and
• Emphasize innovative approaches to pollution control, including incentives,
market-based mechanisms, and cooperative partnerships with landowners and
other private parties.
Based on the efforts of interagency work groups and comments from the public, EPA and
other federal agencies developed the final Clean Water Action Plan that was submitted on
February 14, 1998. One of several Key Actions specifically identified to implement the goals of
the Clean Water Action Plan was EPA's project to re-examine 40 CFR part 434 to better address
coal mining in arid western areas.
Background
1-5
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
On May 28, 1998 (63 FR 29203), EPA announced plans for developing new and revised
effluent limitations guidelines for selected industrial categories, and described revisions to its
t
regulations development process. Included in this program was the re-examination of 40 CFR
part 434. The program and schedule announced in May 1998 were established in response to a
consent decree resulting from legal action taken by the Natural Resources Defense Council
(D.D.C. No. 89-2980, January 31, 1992).
I
1.2.2 Surface Mining Control and Reclamation Act (SMCRA)
1.2.2.1 SMCRA History
In 1977, Congress enacted the Surface Mining Control and Reclamation Act, 30 U.S.C.
1201 etseq, to address the environmental problems associated with coal mining. The previous
lack of uniformity among state surface mining programs and the increase in unreclaimed land
and associated pollution of water and other resources forced the federal, regulation of surface coal
mining activities. SMCRA established a coordinated effort between the states and the federal
government to prevent the abuses that had characterized surface and underground coal mining in
the past, and created two major programs:
• An environmental protection program to establish standards and procedures for
i
approving permits and inspecting active coal mining and reclamation operations
both surface and underground; and
[
• A reclamation program for abandoned mine lands, funded by fees on coal
production, to reclaim land and water resources adversely affected by pre-1977
coal mining.
SMCRA created the Office of Surface Mining Reclamation and Enforcement within the
Department of Interior, and charged it with the responsibility of preparing regulations and
providing financial and technical assistance to the states to carry out regulatory activities. Title V
1-6 Background
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
of the statute gives OSMRE broad authority to regulate specific management practices before,
during, and after mining operations. OSMRE has promulgated comprehensive regulations to
control both surface coal mining and the surface effects of underground coal mining (30 CFR
part 700 et seq). Implementation of these requirements has led to significant improvements in
mining practices and serves to control the pollution of water and other resources.
1.2.2.2 SMCRA Requirements
SMCRA requirements set general performance standards for environmental protection for
any permit to conduct surface coal mining and reclamation operations. The performance
standards that are particularly applicable to the proposed Western Alkaline Coal Mining
Subcategory are summarized as follows:
• Restore the land affected to a condition capable of supporting the uses which it
was capable of supporting prior to mining, or higher or better uses;
• Stabilize and protect all surface areas affected by the mining and reclamation
operation to effectively control erosion;
« Create, if authorized in the approved mining and reclamation plan and permit,
permanent impoundments of water on mining sites as part of reclamation
activities only when it is adequately demonstrated that: such water impoundments
will not result in the diminution of the quality or quantity of water utilized by
adjacent or surrounding landowners for agricultural, industrial recreational, or
domestic uses;
» Minimize disturbance to the hydrologic balance at the mine-site and in associated
offsite areas and to the quality and quantity of water in surface and ground water
systems both during and after surface coal mining operations and during
reclamation;
Background f-7
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
• Establish an effective, permanent vegetative cover at least equal in extent of cover
to natural vegetation or as necessary to achieve the approved postmining land use;
i
• In those areas or regions where the annual average precipitation is twenty-six
'
inches or less, assume the responsibility for successful revegetation for a period of
ten full years;
I
• Protect offsite areas from slides or damage occurring during the surface coal
mining and reclamation operations;
j
• Meet other criteria as necessary to achieve reclamation in accordance with
SMCRA, taking into consideration the physical, climatological, and other
characteristics of the site; and
• To the extent possible using the best technology currently available, minimize
disturbances and adverse impacts of the operation on fish, wildlife, and related
environmental values, and achieve enhancement of such resources where
practicable.
Each SMCRA permit includes detailed pre-mining baseline conditions, a prediction of
the probable hydrologic consequences of mining on the hydrologic balance, a hydrologic
reclamation plan designed to minimize predicted consequences, and a detailed monitoring plan to
verify and characterize hydrologic consequences. However, meeting numeric effluent limitations
under the CWA has taken precedence over SMCRA's requirement to minimize, to the extent
possible, impacts to the hydrologic balance. This precedent has, at times, resulted in adverse
environmental effects and impacts to the hydrologic balance.
Under SMCRA, coal mine operators are required to collect a minimum of one year of
pre-mining or baseline surface and ground water monitoring data before submitting a coal mining
1-8 Background
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
and reclamation permit application. The baseline information is used to prepare site-specific
erosion and sedimentation plans capable of minimizing adverse impacts within the permit area
and adjacent lands. It is also used to perform a Probable Hydrologic Consequences (PHC)
evaluation to identify regional hydrologic impacts associated with the coal mining and
reclamation operation. When potential adverse impacts are identified, appropriate protection,
mitigation, and rehabilitation plans are developed and included in mining and reclamation permit
requirements. The PHC and the accompanying plans are reviewed and approved by regulatory
authorities before mining and reclamation activities are initiated.
Coal mine operators are required to submit bonds covering the costs of reclaiming and
restoring disturbed areas to acceptable environmental conditions in the event of default and
failure to discharge this obligation. During the 5-year life of the permit, the coal mining and
reclamation operations are inspected at a minimum on a monthly basis. Mid-term mining and
reclamation permit reviews and renewals assess the adequacy of the site's erosion and
sedimentation control, treatment, mitigation, and rehabilitation.
Coal mine operators are required to conduct and submit the results of surface and ground
water monitoring under SMCRA and CWA NPDES permits on a periodic basis. Monitoring
results are used to assess the adequacy of erosion and sedimentation control measures. At the
conclusion of mining and reclamation activities, surface water monitoring information is used to
summarize the effectiveness of erosion and sedimentation control in restoring the hydrologic
system. This evaluation is part of a Cumulative Hydrologic Impact Assessment (CHIA) required
when the coal mining company applies for final reclamation liability and bond release.
Background
1-9
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Development Document for Proposed Western Alkaline Coal Mining Subcategory ___
1.2.2.3 Flannery Decision
SMCRA requirements include performance standards for surface mining operations to be
conducted in a manner that minimizes disturbance to the prevailing hydrologic balance.
SMCRA specifies sediment control performance standards for
"conducting surface coal mining operations so as to prevent, to the extent possible using
best technology currently available (ETC A), additional contributions of suspended solids
to stream flow, or to runoff outside the permit area. In no event shall contributions be in
excess of requirements set by applicable state or federal law (30 U.S.C. §
OSMRE implemented the statutory hydrologic balance protection performance standard
by requiring, with some exceptions, that all surface drainage from disturbed areas pass through
sedimentation ponds before leaving the permit area (30 CFR part 816.42(a)(l) and 817.42(a)(l))
In 1981 (46 FR 34784), OSMRE proposed revisions to the siltation structure regulations
that incorporated the flexibility to allow the use of alternative sediment control" measures in lieu
of sedimentation ponds. OSMRE received extensive comments on the question of whether
sedimentation ponds and similar siltation structures constitute BTCA in all circumstances. A
number of comments maintained and supported with data the premise that sedimentation ponds
not only are unnecessary in all cases to meet the statutory requirement to prevent "additional
contributions of suspended solids," but also, in certain circumstances, cause both short and long
term harm to the hydrologic balance. Despite the supporting comments, the final rule
promulgated in 1983 deleted the provision that allowed alternative sediment control measures,
and retained the prior requirement that all drainage from disturbed areas (except for small areas)
pass through a siltation structure before leaving the permit area.
i
The coal industry challenged the blanket requirement in OSMRE's rules that all surface
drainage from disturbed areas pass through a siltation structure before leaving the permit area,
1-10
Background
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
and in 1985 the United States District Court for the District of Columbia remanded the rules as
arbitrary and capricious. Judge Thomas Flannery found that OSMRE failed to adequately
explain why siltation ponds were considered BTCA (In Re Permanent Surface Mining
Regulation Litigation, 620 F. Supp. 1519, 1565-68 D.D.D. 1985). The decision was supported
by record evidence that siltation structures are not always BTCA and OSMRE's recognition that
these structures may pose negative impacts. In 1986 (51 FR 419252), OSMRE suspended the
rule and explained that the regulatory authority will determine on a case-by-case basis what
constitutes BTCA.
In 1990 (55 FR 47430), OSMRE proposed revisions to the federal rules to allow the use
of alternative sediment control measures in lieu of sedimentation ponds in the arid and semi-arid
west. OSMRE never took further action on the proposal. Currently, it is the responsibility of the
regulatory authority to determine, on a case-by-case basis, what constitutes BTCA for preventing,
to the extent possible, additional contributions of suspended solids to stream flow or runoff
outside the permit area.
7.2.3 State Regulatory Guidelines for Sediment Control
The states of Wyoming and New Mexico, under federally approved SMCRA primacy
programs, have developed regulations to allow the use of sediment control BMPs to prevent
environmental problems associated with preferential use of sedimentation ponds in the arid and
semiarid west. The regulations or guidelines have been reviewed and approved by OSMRE.
Utah is developing alternate sediment control guidelines that have not been published to date.
Although the requirements for these programs vary somewhat between states, the intent is to
provide greater protection to the hydrologically sensitive watersheds in this region.
1.2.3.1 Wyoming Coal Rules and Regulations, Chapter IV
Under Wyoming's Coal Rules and Regulations, implemented by the Land Quality
Division (LQD) of Wyoming's Department of Environmental Quality (WY DEQ), exemptions to
Background 1-11
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
the use of sedimentation ponds may be granted where, by the use of alternative sediment control
measures, the drainage will meet effluent limitation standards or will not degrade receiving
i
waters (Chapter IV, Section 2(f)(i)). Chapter IV of these regulations also sets environmental
protection performance standards that require coal mine operators to implement best
management practices including contemporaneous backfilling and grading, reclamation to
approximate original contour, and erosion reduction measurements. Under Chapter IV, Section
2(e)(i), discharges should be controlled as necessary to reduce erosion, to prevent deepening or
i
enlargement of stream channels, and to minimize disturbance of the hydrologic balance.
I
Chapter IV of these regulations also states that appropriate sediment control measures
I
(e.g., stabilizing, diverting, treating or otherwise controlling runoff) shall be designed,
constructed, and maintained using BTCA to prevent additional contributions of sediment to
i
streams or to runoff outside the affected area. Chapter IV requires that a surface
water-monitoring program be used to demonstrate that the quality and quantity of runoff from
affected lands will minimize disturbance to the hydrologic balance. Wyoming's Coal Rules and
Regulations, Chapter IV are provided as Appendix A to this document.
1.2.3.2 Wyoming Coal Rules and Regulations, Guideline No. 15
Wyoming's LQD developed Guideline No. 15 for Alternative Sediment Control Measures
(ASCMs) or best management practices that may be used in addition to or in place of
sedimentation ponds. The guideline supports requirements of the Wyoming DEQ/LQD Coal
Rules and Regulations, Chapter IV and provides guidance for determining best technology
currently available for designing, constructing, implementing, and maintaining AS CM, and for
detennining the contents of an ASCM proposal.
Guideline No. 15 identifies specific sediment control measures that may be used in
addition to or in place of sedimentation ponds and supports the use of alternative sediment
control measures as an option under Wyoming's Coal Rules and Regulations. Guideline No. 15 '•
recommends: determination of BTCA on a case-by-case basis, prevention of soil detachment and
1-12 Background
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
erosion, retention of sediment as close as possible to its point of origin, and implementation of
sediment traps only as a second line of defense. Wyoming's Guideline No. 15 are provided in
Appendix B of this document. A summary of the guideline is presented below.
Determination of Best Technology Currently Available
Guideline No. 15 recognizes that design methods, construction techniques, maintenance
practices, and monitoring all contribute to a system that can be considered BTCA. Additionally,
the guideline recognizes that BTCA must be determined on a case-by-case basis. Factors
considered in BTCA determinations include the size and type of disturbance and the length of
time the ASCM will be in place. Determination also should be based on how effective the
ASCM is at preventing soil detachment and erosion, and how effective the ASCM is on retaining
sediment as close as possible to its point of origin.
Design of ASCM (for areas 30 acres and larger)
For sites larger than 30 acres, the mine operator is required to submit a general
description of the area to be controlled by ASCM and the types and duration of expected
disturbance, including the distance to and type of nearest receiving stream. A description of the
sediment control plan, including justification for ASCM design parameter values and date of
construction or implementation, is to be included. The use of site-specific data is encouraged.
Topographic maps detailing the use of ASCM in relation to the mining and reclamation sequence
is required. Annual reports detailing ASCM modifications are required if adjustments are made
to the approved permit system. The guideline recommends that the ASCM design be based on
predicted sediment loads or yields from the area disturbed compared to predicted or measured
native sediment yields. State-of-the-art computer watershed models are recommended for use as
a design tool.
Design of ASCM (for areas less than 30 acres)
Sediment control design requirements for small disturbed areas are concerned primarily
with establishing use and safety criteria commensurate with the intended use and life of the
structures. For these areas, the operator is required to submit the sedimentation control plan and
Background 1-13
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
justification, a plan view location, and a general description of the type of ASCM structures. The
sediment control plan should implement sediment trapping structures to pass or detain runoff
from storm events such as toe ditches and rock check dams. ASCM proposals for small areas
also should present the inspection and maintenance programs the operator will use to regularly
evaluate the stability and effectiveness of each ASCM. The program recognizes that the
effectiveness and capabilities of many ASCM have been documented and need not be reiterated
for small area application.
Implementation Priorities (for post-mining surfaces)
Guideline No. 15 highly recommends ASCM design approaches that stabilize land forms
to minimize sediment yield. Short-term slope erosion control methods are recommended, such
as regrading, mulching, and rapid establishment of vegetation. The guideline also recommends
in-channel sediment retention and removal of trapped sediment. Sedimentation ponds should be
implemented when maintenance of ASCMs is a chronic problem.
ASCM Performance Monitoring
Monitoring of small ephemeral receiving streams should include visual inspection
following each runoff event, and repeat photographs taken at least annually and after major
runoff events. Monitoring of large ephemeral receiving streams should include visual inspection,
repeat photographs, repeat surveys, and upstream and downstream sediment yield monitoring
stations. Guideline No. 15 recognizes that each type of ASCM has construction and maintenance
guidelines that are specified in most handbooks on sediment control. The operator is required to:
"report, repair and log any significant damage to an ASCM as soon as possible after the
damage occurs. The operator should inspect the ASCM at the beginning and at the end of
each runoff season, and after each runoff event. An inspection and maintenance log
should be kept to document the condition of each ASCM at the time of each inspection.
The log should describe any damage, required maintenance, and the date repairs were
made."
1-14
Background
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
1.2.3.3 New Mexico's ASC Windows Program
New Mexico's Mining and Minerals Division (MMD) enforces the state's federally
approved SMCRA primacy program. BMP regulations for mining and reclamation operations in
New Mexico may be found under 19 NMAC 8.2 Subpart 20 Section 2009 which addresses
requirements for minimizing changes to the prevailing hydrologic balance in both the permit and
adjacent areas. Section 2009 of Subpart 20 is included as Appendix C of this document.
Under New Mexico's program at Section 2009.E (commonly referred to as the "ASC
Windows Program"), requirements to pass all disturbed area runoff through a sedimentation pond
or series of sedimentation ponds can be waived. If the operator chooses not to operate under the
provisions set forth at 2009.E, then all runoff must be passed through sedimentation ponds before
leaving the permit area. To waive sedimentation pond requirements, the operator must
demonstrate that erosion is sufficiently controlled and that the quality of area runoff is as good as
or better than that of water entering the permit area. The regulations recognize that certain
methods are capable of containing or treating all surface flow from the disturbed areas and shall
be used in preference to the use of sedimentation ponds or water treatment facilities. These
practices to control sediment and minimize water pollution include, but are not limited to:
• Stabilizing disturbed areas through land shaping, berming, contour furrowing, or
regrading to final contour;
• Planting temporary vegetation that germinates and grows quickly;
« Regulating channel velocity of water and diverting runoff;
• Lining drainage channels with rock or revegetation; and
» Mulching disturbed areas.
The operator's plan for alternative sediment control must demonstrate that there will be
no increase in the sediment load to receiving streams. The plan also must demonstrate that there
will be no resulting environmental harm or degredation, threat to public health or safety, or
Background ~~ 1-15
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Development Document for Proposed Western Alkaline Coal Mining Subcategory
resulting pollution or other diminishment of existing streams and drainages that could cause
imminent environmental harm to fish and wildlife habitats. The operator is responsible for
taking baseline and ongoing surface and ground water monitoring samples. The MMD may
require additional tests and analyses as deemed necessary by baseline and ongoing monitoring
results. Surface water monitoring continues until final bond release.
Several mine operations in New Mexico have applied for and received reclamation
liability bond releases for lands where sediment control BMP plans were implemented (e.g.,
I
Carbon II mine and De-Na-Zin mine). These sites demonstrated that there was no contribution of
I
additional suspended solids to the hydrologic regime of the area and that runoff from regraded
areas was as good as or better than runoff from undisturbed areas (WCMWG, 1999a).
1-16
Background
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' '. Development Document - Proposed Western Alkaline Coal Mining Subcateeorv
Section 2.0 Industry Characterization
This section describes the coal mining industry in the arid and semiarid areas west of the
100th meridian and details the environmental factors that make mining and reclamation activities
in these areas different than coal mining in the rest of the United States.
2.1 Location and Production
The United States is divided into three major coal producing regions: Appalachian,
Interior, and Western (Figure 2a). Mines affected by the proposed Western Alkaline Coal
Mining Subcategory are within the Western Coal Region and are defined as mines that:
• Are west of the 100th meridian west longitude,
• Are located in arid or semiarid areas with an average annual precipitation of 26 inches or
less, and
• Produce alkaline mine drainage.
The Western Coal Region contains extensive deposits of low-sulfur coal (Figure 2a).
Most of the coal mined in the Western Region is sub-bituminous, i.e., has a lower Btu content
(8,3000 - 13,000) than eastern bituminous coal (>13,000). Western coal seams lie at various
depths below the surface and vary in thickness from a few inches to over 70 feet (Energy
Information Administration, 1995). The economic ability to mine the coal seams varies
throughout the region and is dependent on coal quality, seam thickness, depth of overburden,
geologic characteristics, and market factors. In areas such as the Southern Powder River Basin of
Wyoming, thick coal seams and shallow overburden enable the extraction of large volumes of
coal at relatively low cost. The low-sulfur content, in demand since the passage of the Clean Air
Act, and the potentially low cost of extraction mean that coal resources in the Western Coal
Region represent a highly competitive fuel in the power generation market. As the fuel market
Industry Characterization
2-1
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
has changed, coal production within the Western Region has increased, now being nearly equal
to the formerly dominant Appalachian Region. The United States produced 1.1 billion short tons'
of coal in 1997, with the Appalachian Region producing 469 million short tons, the Interior
i
Region producing 172 million short tons, and the Western Region producing 451 million short
tons (Table 2a).
Figure 2a: Coal Producing Areas (modified from USGS, 1996)
lOO* Meridian
Ugnte
SubbitummJsCoal
MedimandHgh-VolaSte
BHum'nousCoal
Low-Volatile Bituminous Coal
Anthracite and Semianthradte
2-2
Industry Characterization
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Development Document - Proposed Western Alkaline Coal Minim Subcatesorv
Table 2a: United States Coal Production by Region (short tons; Energy Information
Administration, 1997)
Appalachian Region
Interior Region
Western Region
Total
1970
427,600,000
149,900,000
35,100,000
612,600,000
19971
468,778,000
' 171,863,000
451,291,000
1,089,932,000
The total does not equal the sum of components due to independent rounding.
While domestic coal production has increased since 1970, fewer operating mines exist
today, representing higher mine production, In 1997, the number of mines producing coal was
less than half the number producing coal in 1988 (e.g., 3,860 mines in 1988 compared to 1,828
mines in 1997), and in the Western Region the number of mines fell from 114 to 77 in the same
time period (Energy Information Administration, 1997). According to the Energy Information
Administration, in 1988, the Western Region produced approximately 308 million short tons of
coal, 68 percent of the 451 million short tons of coal the Western Region produced in 1997
(Energy Information Administration, 1997).
Of the 77 mines operating in the Western Region, EPA has identified 47 surface mines
that potentially will be affected by the proposed Western Alkaline Coal Mining Subcategory.
One of these mines, however, currently is in the final reclamation phase and most likely will be
unaffected. The 47 mines produce approximately 497 million tons of coal annually, affect
192,411 acres of land, and are located in Arizona (2 mine sites), Colorado (5 mine sites),
Montana (6 mine sites), New Mexico (6 mine sites), and Wyoming (28 mine sites). These sites
are listed along with operation and production statistics in Table 2b.
Industry Characterization
2-3
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Table 2b: Operation and Production Statistic of Potentially Affected Coal Mines in the
Arid and Semiarid Coal Producing Region (modified from Western Coal
Mining Work Group, 1999b).
STATE
AZ
AZ
CO
CO
CO
CO
CO
MT
MT
MT
MT
MT
MT
NM
NM
NM
NM
NM
NM
WY
WY
WY
WY
WY
WY
WY
MINING
SINCE'
Jan-70
May-74
Feb-77
Pending
-
Jan-64
Jan-77
Jul-94
Jan-69
Feb-71
Jan-68
Oct-58
Dec-80
Aug-86
Jan-84
Jan-64
Jan-63
Jan-73
Feb-89
Jan-83
-
Nov-72
-
-
Aug-76
Jan-81
ANNUAL
PRODUCTION
(1,000s of tons)2
4,634
7,090
5,544
0
-
1,350
2,002
7,051
4,335
117,000
9,146
330
9,015
2,375
4,900
6,607
8,200
4,072
1,259
13,559
0
22,800
80
1,857
50,000
18,000
AVG.
$/TON
(STATE'3
$ 25.17
$ 25.17
$ 18.46
$ 25.00
$ 18.46
$ 18.46
$ 18.46
$ 9.84
$ 9.84
$ 9.84
$ 9.84
$10.10
$ 9.84
$ 21.83
$ 21.83
$ 21.83
$ 26.00
$21.83
$ 6.00
n.a.
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 4.00
YEARLY
VALUE
(l,000sj"
$ 116,638
$ 178,455
$ 102,342
-
-
$ 24,921
$ 36,957
$ 69,382
$ 42,656
1,151,280
$ 89,997
$ 3,333
$ 88,708
$ 51,846
$ 106,967
$ 144,231
$ 213,200
$ 88,892
$ 27,484
$ 81,354
-
$ 136,800
$ 480
$ 11,142
$ 300,000
$ 72,000
INDIAN
LANDS
Navajo &
Hopi
Navajo &
Hopi
No
No
No
No
No
No
No
No
No
No
No
No
No
Navajo
Navajo
No
No
No
No
No
No
No
No
No
AFFECTED
ACRES5
6,255
13,604
2,782
0
-
-
5,116
-
3,437
6,093
-
430
2,251
1,799
3,800
13,000
7,188
4,969
-
3,059
249
11,621
1,969 :
14,860
13,017
3,789
MINE
LIFE
(YEARS)
6
12
16
15
-
-
16
-
6
28
-
20
17 .
18
30
12
18
18
-
18
-
-
-
-
24
-
PROJECTED
DISTURBANCE
. (ACRES)
7,236
16,351
3,810
1,161
-
-
6,300
-
500
8,579
-
875
4,485
2,085
11,300
4,546
11,000
6,216
-
5,172
-
-
-
-
12,172
-
2-4
Industry Characterization
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Development Document - Proposed Western Alkaline Coal Minine Su
STATE
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
WY
Total
SINCE1
Jan-78
Nov-82
-
Dec-76
Oct-58
-
Jan-78
Mar-976
Aug-76
May-73
Jan-50
Jan-74
Jan-83
Sep-89
Nov-77
Nov-85
-
Jan-73
Oct-76
-
Jan-22
-
PRODUCTION
(1,000s of tons)2
19,946
14,681
5,805
13,324
4,200
2,986
17,921
1,005
27,113
6,231
4,402
600
34,965
5,000
10,706
26,640
-
500
769
-
3,242
496,608
$/TON
(STATED
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 9.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
$ 6.00
>
YEARLY
VALUE
(l.OOOs^4
$ 119,676
$ 88,086
$ 34,830
$ 79,944
$ 37,800
$ 17,916
$ 107,526
$ 6,030
$ 162,678
$ 37,386
$ 26,412
$ 3,600
$ 209,790
$ 30,000
$ 64,236
$ 159,840
-
$ 3,000
$ 4,614
-
$ 19,452
4,235,243
INDIAN
LANDS
No
No
No
No
No
No
No
• No
No
No
No
No
No
No
No
No
No
No
No
No
No
-
AFFECTED
ACRES5
9,686
2,374
8,310
4,576
4,590
3,124
5,706
145
5,624
7,792
10,622
5,551
2,687
4,016
8,316
7,041
-
3,523
1,011
-
959
192,411
MINE
LIFE
(YEARS)
-
14
-
14
9
-
-
28
15
25
26
12
-
-
-
-
-
12
-
-
32
-
PROJECTED
DISTURBANCE
(ACRES)
-
6,631
-
7,275
2,000
-
-
1,886
8,207
10,429
4,960
5,765
-
-
-
-
-
3,576
-
-
2,129
141,521
J.TJ.VJ.1U.A UIJU. JTl/CU XJL.V/JLJLJ. A-/V-/J-* UaLClU/UO&.
21997 or 1996 reported total annual production obtained from either the Keystone Manual (cite) or the Department
of Energy Web site (cite).
3The average value of a ton of coal sold by all reporting mines in the state in which the mine is located. Where state
values are unavailable, the Western Region average value was used.
4The Annual Production figure multiplied by the average price/ton.
5The total number of all acres disturbed to date by the mining operation. Acres disturbed for the extraction of coal
are contemporaneously reclaimed (i.e., within four spoil ridges or 180 days whichever comes first), unless
a variance is approved by the regulatory authority.
6The date of last permit transfer. Mining commenced prior to this date.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
2.2 Environmental Conditions
Coal mining operations potentially affected by the proposed Western Alkaline Coal
Mining Subcategory operate under environmental conditions that are noticeably different from
those in other regions of the United States. Background surface conditions are defined in this
environment by the direct response of the geologic and soil-forming environment to the arid
climate. Climatic, geologic, soil-forming, and topographic factors directly influence distribution
and composition of vegetation in the arid and semiarid west. Western arid and semiarid areas are
naturally unstable with highly eroded landscapes that are created by flash flooding which
transports large volumes of sediment. Water resources are severely limited and highly valued.
Common conditions occurring throughout the arid and semiarid western coal-bearing region are
summarized categorically below.
I
2.2.2 Temperature
Temperatures in the arid and semiarid western United States fluctuate over wide daily and
seasonal ranges. A daily range of 30°F to 50°F (-1°C to 10°C) is common, while the seasonal
temperature ranges from -40°F to 115°F (-40°C to 46°C). Large diurnal fluctuations contribute
to the physical weathering of surface materials, which increases the amount of small sediment
particles available for transport by runoff generated during significant storm events. Intense
wind storms generated by frontal weather systems and regional weather patterns in this region
i
also can transport substantial amounts of sediment.
2.2.2 Precipitation
Arid and semiarid locations average 26 inches or less of annual precipitation, with
roughly equal parts occurring as snowfall and rainfall. Average annual precipitation received in
western states containing arid and semiarid areas is presented in Table 2c.
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Development Document - Pronosed Western Alkaline Coal Mining Subcatesorv
Table 2c: Average Annual Precipitation (inches) in Arid and Semiarid Coal States
(from National Oceanic and Atmospheric Administration, 1998)
State
Arizona
Colorado
Montana
New Mexico
Wyoming
Long-Term Average Annual Precipitation (inches)
1899 - 1998
12.77
15.90
15.36
13.45
13.16
Much of the rainfall in the arid and semiarid western United States is received during
localized, high-intensity, short-duration thunderstorms, and research has indicated that relatively
few storms may produce the greatest amount of erosion (Peterson, 1995). Western precipitation
storms producing runoff are typically:
• Cellular in nature - localized intensity and relatively limited in areal extent;
• Of short duration; and
• Characterized by large raindrops with high kinetic energy.
Studies of precipitation typically received in arid areas indicate that the dominant
precipitation events that produce runoff generally have between 1-hour and 3-hour duration
peaks. For arid lands, up to 80 percent of the total 24-hour rainfall occurs within 3-hours
(Hromadka, 1996). These storm events result in short-duration, sediment-rich flash flood runoff.
Hjemfelt (1986) reported that only three to four percent of storm events accounted for 50 percent
of long term sediment yields.
Evapotranspiration normally exceeds precipitation since solar energy is high in western
arid and semiarid areas and humidity is characteristically very low. Water infiltration and
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Development Document - Proposed Western Alkaline Coal Mining Subcategory _,
retention in the soil is frequently limited, creating a net negative water balance. The negative
water balance results in severe soil moisture deficits, extremely limited surface water resources,
and poor plant growth and cover.
2.2.3 Erosion Prone Soils
Soils in arid and semiarid areas tend to be prone to erosion and weathering. On steep
slopes, soil-forming materials frequently erode faster than they are formed. Where erosion rates
are lower and soil is capable of forming, the soil typically is poorly developed with low organic
matter and plant nutrient content. Soil moisture contents are characteristically low because of
limited precipitation, low soil infiltration rates, and nominal amounts of organic matter.
A source of erosion is the energy created by "raindrop splash." Raindrops contain enough
energy to mobilize sediment and transport it down slope. In a sediment rich environment,
overland flow reaches its suspended solids carrying capacity after a short distance or period of
time. When overland flow reaches dynamic sediment loading equilibrium, entrained particles are
dropped and new ones are picked up until the kinetic energy of the flow is changed. When
overland flows decrease in velocity, such as at the base of a concave slope, kinetic energy
decreases, and entrained sediments are released and deposited. Ephemeral gullies on these lands
carry flow only at times of severe storm or spring snowmelt (Heede, 1975).
i I
2.2.4 Hydrology and Sedimentation
The western region of the United States is geomorphically young and active with a
weathered topography. The landscape in the arid and semiarid regions is a mixture of mountains,
mesas, plains, buttes, valleys, and canyons, and the effects of active erosion, flash flooding, and
other dynamic geologic processes are pervasive. Flow channels frequently contain multiple
terrace levels. Instability within drainage systems is readily observed with channel head-cutting,
aggradation, bank slumping and actively changing watercourses commonly occurring.
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'. Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
Perennial rivers are predominant in this region and most commonly originate in
mountainous areas with significant snow (in areas with average annual precipitation greater than
26 inches per year) or in very large watersheds. Ephemeral drainage systems predominate in
small to medium-sized headwater areas. These ephemeral drainage systems are composed
primarily of dry washes and arroyos, the lower ends of such features sometimes being depicted
on USGS topographic maps as intermittent streams. More often than not, drainage features thus
depicted:
• Conduct ephemeral surface water flow;
« Are mainly composed of sand bed channels;
• Have channel banks of unconsolidated alluvial deposits;
« Possess a nearly unlimited source of sediment that may be transported by flash
flooding; and
« Commonly contain sediment at concentrations as high as 1 x 106 mg/L during
flash flood runoff events.
For an average of 11 to 11 Vz months a year the washes and arroyos are dry, normally
flowing only in direct response to precipitation runoff. When rainfall does generate runoff, it is
frequently characterized by high-volume, high-velocity, sediment-laden, and turbulent flows with
tremendous kinetic energy that ceases soon after the precipitation event stops. For many very
short-duration precipitation events, the runoff water never reaches the main-stem channels
downstream. This turbulent flow pattern establishes a fluvial dynamic equilibrium in arroyos
and washes that is characterized by episodic aggradation and degradation of channel morphologic
characteristics. The sediment is continually transported down-stream, normally at the maximum
level of concentration possible for the kinetic energy available within a given flow.
Floodplains that develop on arid landscapes are wide and unstable, as the morphology
and position of the main stem channels change with every major precipitation event. The
migration of the channels across the landscape redistributes the sediment, with the primary
source of sediment the mass wasting of the vertical sides of the arroyo channels. In comparison
to the total amount of sediment involved in erosion, transport, and deposition during runoff from
a given storm event, a relatively small amount of sediment actually leaves the watershed.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
I
2.2.5 Vegetation
The response of vegetation to the low amount of precipitation in the arid and semiarid
coal regions is evident. The major vegetation zones in this western environment are desert, grass
and brush lands, and open forests types (e.g., pinyon-juniper and ponderosa pine) characterized
by discontinuous and sparsely distributed grasses, forbs, shrubs, and trees. Species composition
varies from north to south and at various elevations. Slope, aspect, moisture retention, and solar
insulation play a significant role in the distribution of plants within a given area. Most plants
within the arid and semiarid precipitation zones have adapted their ability to germinate, establish,
and grow to the dry conditions and cycles prevalent throughout the region. With moisture
availability being the primary limiting resource to plant growth, floral adaptations and growth
habits center around a variety of moisture harvesting, conservation, and retention strategies.
Living ground cover is frequently sparse, although cumulative ground cover may be significant
since decomposition tends to be retarded by limited moisture availability.
2.2.6 Watershed Runoff Characteristics
\
Ephemeral and intermittent flows in the arid and semiarid western United States are
unique in their flow and duration characteristics. Runoff generated by a single storm event may
last from a few minutes to hours depending upon the size and characteristics of the affected
watershed. Typically, flows last a few hours and, except for a high-water debris line, any
evidence of their passage is gone within 48 hours or less. Frequently, flows run above ground for
short to moderate distances, and gradually dissipate into the beds of the dry washes and arroyos
j
they have followed or created.
While storms in this region typically drop less precipitation than their eastern
counterparts, the intensity is often greater, and the amount of runoff generated is normally equal
to or greater than that created by an eastern precipitation event of equivalent size. The increased
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_. Development Document - Provosed Western Alkaline Coal Mining Subcateeorv
runoff occurs because the poorly developed soil and sparse vegetation of western areas have a
greatly reduced capacity to capture and harvest precipitation. The water that collects and drains
from western precipitation events is nominally impeded and runoff characteristically takes the
form of turbulent, high-velocity, flash floods. Rising stages often start initially as a trickle of
water, followed by a wall of water roaring through the channel a few minutes later. Multiple
crests may occur as subwatershed runoff is delivered to a main channel. As the flow recedes,
velocity and volume fall off rapidly and trickle to an end over a period of a few hours.
Sediment concentration in these turbulent flows normally has a direct relationship to their
kinetic energy. Sediment is in abundance within the channels where flow occurs and occurs at
concentration levels near or at flow carrying capacity. Sediment concentration frequently varies
over a wide range of concentration levels during a given flow event. Sediment content from a
few thousand to 500,000 mg/L may be expected with values in the 25,000 to 150,000 mg/L range
being common. The variation occurs primarily with changes in flow volume and velocity,
although rising and falling stages may exhibit differing sediment concentrations at similar stage
heights.
2.2.7 Cum ulative Effect
The cumulative effect of the geologic, hydrologic, and climatic conditions unique to this
arid and semiarid region can be summarized as follows:
• Western arid and semiarid areas are naturally geomorphically unstable;
• Landforms frequently exhibit dynamic geomorphologic and erosion processes;
• There is virtually an unlimited supply of sediment available within the arroyos and
washes;
• Large volumes of sediment are normally transported by short duration, flooding,
and turbulent flows;
• Particle erosion from a rough steep topography contributes dramatically to the
natural generation of sediment;
• The runoff pattern predominating in ephemeral watersheds is flash flooding; and
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
• The sediment yield in tons per acre per year from these lands is significantly
higher than from similarly undisturbed vegetation covered lands of the
mid-western and eastern United States.
Although water is sparse, the amount of water that physically runs off is significant due to
the nature of the soils and the lack of effective surface cover. It is this ranoff that has created the
highly-eroded landscape and variable topography that is prevalent throughout this region.
Environmental conditions limit surface and shallow subsurface water resources and the
distribution and development of aquatic and riparian biologic resources. Direct use of
surface-water runoff by man and wildlife also is limited due to its sporadic availability and poor
physical quality. The limited surface-water resources that do occur within the region have high
habitat and use values. Infiltration of surface runoff to local water tables provides limited, but
valuable, useable ground-water resources.
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; : Development Document - Proposed Western Alkaline Coal Mining Subcategory
Section 3.0 Best Management Practices
Current control and treatment technologies used to meet effluent limitations for settleable
solids (SS) at coal mining and reclamation operations in the arid and semiarid western United
States are based primarily on the implementation of sedimentation ponds. This section details
the problems that have been associated with the use of sedimentation ponds in arid and semiarid
regions, presents the theory behind BMP implementation, presents modeling techniques that aid
in BMP design and prediction of BMP effectiveness, and describes the site-specific sediment
control measures and techniques that may be employed.
3.1 Sediment
In arid and semiarid watersheds, sediment can be defined as all material transported by
surface water drainage, including dissolved, total suspended, and settleable solids and bedload.
In this environment, climate, topography, soil, vegetation and hydrologic components all
combine to form a hydrologic balance that is naturally sediment rich. The dynamic fluvial
systems in these watersheds depend upon a continuous source and flow of sediment to maintain
the existing natural sediment balance. Consideration of the importance of sediment balance in
this region is as critical as the availability of water.
3.2 Sedimentation Pond Use and Impacts in Arid and Semiarid Regions
The numeric effluent limitations established at 40 CFR part 434 for discharges in mining
and reclamation areas were based upon the treatment capabilities of sedimentation ponds, with
nominal consideration of the impacts on the environment in the Western Region.
Implementation of sedimentation ponds to meet these numeric effluent limitations has taken
precedence over SMCRA's requirement to minimize possible impacts to the hydrologic balance.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Reliance on sedimentation ponds as the primary technology to control sediment and to
achieve effluent limitations has resulted in the construction and operation of a significant number
of ponds at coal mining and reclamation operations in the arid and semiarid west (Western Coal
Mining Work Group, 1999a). While sedimentation ponds may be capable of achieving the
i
sediment concentration reductions necessary to meet EPA discharge limitations, the net effect of
achieving those reductions can represent a major disruption of the hydrologic balance that may
rival, if not exceed, the impact of the mining operation (Doehring, 198.5). In summary,
sedimentation pond use in arid and semiarid western regions can:
• Require significant additional surface disturbance;
• Result in environmental harm through the disruption of hydrologic balance;
• Adversely affect valuable riparian or aquatic communities; and
• Create contention during the administration of basin water rights.
3.2.1 Surface Disturbance
Due to topographic constraints, lease boundary constraints, and a high occurrence of
ephemeral and intermittent drainage within western surface coal mine permit areas,
sedimentation ponds are often constructed within natural drainage ways that convey surface
runoff from both disturbed and undisturbed areas (Simons. Li & Associates, 1982). The larger
volumes of runoff and sediment from these combined areas must be detained long enough to
achieve CWA effluent limitations, requiring the construction of larger ponds and the disturbance
of larger surface areas. With the establishment of the SS limits at 40 CFR part 434,
sedimentation ponds were upgraded through expansion and new ponds were designed to increase
detention times by providing larger volume capacity.
i
As an example of the significant impact of sedimentation ponds in arid and semiarid
environments, the Western Coal Mining Work Group provided the following information from
four coal mining sites. A breakdown of the number of sedimentation ponds being used, area
disturbance and acres of watershed drainage at each mine site is presented in Table 3a. The
Pittsburg & Midway Coal Mining Company's McKinley Mine in New Mexico uses 79 ponds,
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
BHP Coal Company's Navajo Mine in New Mexico uses 30 sedimentation ponds, and
Pacificorp's Dave Johnston Mine in Wyoming operates 14 sedimentation ponds. There are
currently 149 sedimentation ponds with the potential to impound 4,500 acre-feet of water at the
Peabody Western Coal Company's Black Mesa Mine in Arizona. The total area of disturbance
from the implementation of these sedimentation ponds is approximately 887 acres, resulting in an
average of 3.3 surface acres disturbed per sedimentation pond.
Table 3a: Area Disturbance and Watershed Drainage of Sedimentation Ponds at Four
Western Mine Operations (Western Coal Mining Work Group, 1999a)
Mine Site
Black Mesa Mine
McKinley Mine
Navajo Mine
Dave Johnston Mine
Total
Number Of
Sedimentation Ponds
149
79
30
14
272
Acres
Disturbed
540
211
100
36
887
Watershed Acres
Draining Into Ponds
45,720
7,050
4,331
4,567
61,668
In contrast, Bridger Coal Company's operation in southern Wyoming (Section 5, Case
Study 2) has successfully applied alternative sediment control measures for over 5,260 acres with
only 3.9 acres of additional disturbance. If sedimentation ponds had been implemented at this
site, the extensive surface area affected by mining and the drainage density would require
operation of roughly 200 sedimentation ponds disturbing roughly 660 acres to control all runoff
during the life of the mine.
3.2.2 Water Impoundment
Sediment control historically has focused on the capture of surface water runoff in
"sedimentation ponds located on the bottom periphery of disturbance areas (Western Coal Mining
Work Group, 1999a). Surface water runoff contained in a sedimentation pond is typically
allowed to evaporate, and therefore, is not available for downstream or consumptive uses.
Sedimentation ponds typically are sized to treat or contain the combined sediment and
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
runoff volume resulting from a 10-year, 24-hour storm event (Appendix C: 19 NMAC
i
8.2.20.2014, 1997). A result of the implementation of this design in arid and semiarid regions is
that, for the majority of storm events, downstream channel flow is either eliminated or
significantly attenuated. Loss of runoff water, through the storage of runoff in sedimentation
ponds, evapotranspiration, and localized infiltration, can significantly affect the local hydrologic
balance, downstream resources, ground water hydrology, and the spatial pattern of alluvial
recharge (Doehring, 1985).
Sedimentation ponds have the potential in some cases to disrupt hydrologic balances and
impact associated environmental resources. Downstream surface runoff volumes may be
drastically reduced or completely eliminated if non-discharging structures are used for sediment
treatment, and typically are reduced 80 to 90 percent below pre-mining flow rates when
discharging ponds are used for water treatment (Western Coal Mining Work Group, 1999a).
Disruption of flow volume at this magnitude is a concern in arid and semiarid regions. Avoiding
or minimizing disruption to stream flow is also a "key program objective and activity to be
undertaken in the next decade" by the Water Quality Criteria And Standards Plan-Priorities for
the Future (U.S. EPA, 1998).
The National Mining Association employed computer modeling techniques to predict
BMP and sedimentation pond performance and resulting sediment yield at a reclamation area for
a representative model mine in the arid and semiarid west (Western Coal Mining Work Group,
i
1999c). Details of this prediction study are presented in Section 5, Case Study 1 and in
Appendix D of this document. The maximum storage capacity of sedimentation ponds used for
the model was 60 acre-feet. This means that of 73 acre-feet of runoff (predicted from a 10-year,
24-hour precipitation event affecting the reclaimed area and adjacent undisturbed areas), only
about 13 acre-feet of drainage will pass through the sedimentation ponds into the down-drainage
system. The model assumed an additional 30 acre-feet of water would be released from the pond
system to the downstream watershed by automatic dewatering over an 8-day period. This
represents only 41 percent of the drainage volume predicted to occur under undisturbed
conditions. In addition, the peak flow was predicted to be 45 cfs when sedimentation ponds are
implemented and 602 cfs when alternative sediment control BMPs are implemented. This peak
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
flow compares to 679 cfs predicted to occur naturally under undisturbed conditions.
BMP systems minimize disruption to the hydrologic balance through the use of alternate
sediment controls (Western Coal Mining Work Group, 1999c). The mine model predicts that,
with BMP system application, approximately 73 acre-feet of water would be released
downstream from the example reclamation watershed as a result of the receipt of a 10-year,
24-hour precipitation event. By depriving downstream channels of small but relatively frequent
flows, channel geometry is not maintained (Doehring, 1985). Unused channels are modified by
the processes of mass wasting; caving banks and slope processes that destroy the channels and
eliminate their ability to convey flows of sediment and water. In cases where some flow is
maintained, a small, "underfit", inner channel is produced. While sedimentation ponds may be
capable of achieving the sediment concentration reductions necessary to meet EPA discharge
limitations, the net effect of achieving those reductions is often the triggering of large bursts of
sediment produced by channel adjustments. When substantial flows return, either due to a high
yield storm or due to removal of the sedimentation pond, accelerated erosion and flooding can be
expected and any riparian vegetation that had been established can be destroyed.
Many western states have long recognized the social and economic importance of their
limited surface water and ground water resources and have instituted water rights procedures to
prioritize and allocate beneficial usage. However, in order to achieve existing CWA effluent
criteria for coal mining operations, regulations and guidelines emphasizing the construction of
sedimentation ponds commonly consider as secondary or completely ignore the potential
disruption this treatment technology often has on downstream water rights and users. Regardless
of the magnitude of drainage area controlled, the construction and operation of sedimentation
ponds reduces the amount of surface runoff available for downstream users. The loss of surface
water runoff and ground water recharge due to sedimentation ponds continues to be an issue in
water rights negotiations (Western Coal Mining Work Group, 1999a).
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5.2.3 Sediment Retention
In arid and semiarid western coal mine regions, large amounts of sediment are readily and
i
naturally transported. Sediment is an important and integral part of these hydrologic systems. In
fact, these systems depend upon a continual source and flow of sediment to maintain the existing
natural sediment balance.
In order to predict the amount of sediment that will be transported out of a representative
model mine in an arid western watershed, the Western Coal Mining Work Group implemented
SEDCAD 4.0 (Western Coal Mining Work Group, 1999c). With the implementation of
sedimentation ponds to comply with current effluent guidelines, SEDCAD 4.0 estimated that 0.0
acre-feet of sediment per year would be transported out of the watershed. With implementation
of appropriate alternative sediment control BMPs, SEDCAD 4.0 estimated that 6.7 acre-feet of
sediment per year would be transported out of the watershed, which closely approximates the 8.3
acre-feet per year estimated sediment yield for an undisturbed watershed. The essential
containment realized by the sedimentation ponds represents a gross dissruption of sediment
movement through the fluvial system.
3.2.4 Scouring and Seeps
SMCRA requires operators of coal mines to prevent, to the extent possible, additional
contributions of sediment to receiving waters, and to protect the balance of the hydrologic ;
system. Since sediment is an integral part of the arid and semiarid geomorphic and hydrologic
system, maintenance of background levels of sediment in mine discharges is crucial to
maintaining the hydrologic balance (Water Engineering and Technology, 1986). At times of
normal runoff in this region, sedimentation ponds intercept and detain virtually all flow and
waterborne sediment, including both the natural and the mining-generated components
(Doehring, 1985). Any clean water released from the ponds tends to degrade channel beds in the
reach immediately downstream (Williams and Wolman, 1984). When discharges from
sedimentation ponds occur, the essentially sediment-free water begins to immediately entrain
sediment from the fluvial system below the pond and potentially accelerate the erosion process.
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\ Development Document - Proposed Western Alkaline Coal Mining Subcategory
The combination of localized scour coupled with attenuated flows typically causes the
incised channel width to decrease within this reach. At the same time, the construction of the
sedimentation pond decreases the gradient of the channel reach immediately upstream from the
pond, and sediment tends to deposit in that area. Sediment scoured from the reach immediately
downstream from the pond is deposited a short distance downstream as flow in the alluvial
channel quickly infiltrates the surface and diminishes. Riparian and other hydrophytic vegetation
are limited in arid and semiarid regions, and fluctuations in water tables fed by surface water
runoff can cause these valuable biologic communities to shrink considerably or even disappear.
Another impact from the implementation of sedimentation ponds is the occurrence of
intermittent seeps that have been observed and monitored at several sedimentation ponds since
the early 1980s (Western Coal Mining Work Group, 1999a). Intermittent seeps reported at
Peabody Western Coal Company's Black Mesa Mine have developed as a result of impounded
water interacting with local geologic materials in the vicinity of the sedimentation pond
embankments. These seeps are expected to persist intermittently at several pond locations until
the ponds are removed and reclaimed. Concerns expressed by local residents resulted in an EPA
requirement to study the seeps, report the findings of the study, and develop a plan to mitigate the
seeps as part of the Black Mesa NPDES permit. The formation of springs and seeps in the
immediate downstream vicinity of sedimentation ponds also can result in a localized proliferation
of vegetation that can encroach on channels (Williams and Wolman, 1984).
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3.3 Sediment Control BMPs
Erosion and sediment controls are used to reduce the amount of soil particles that are
carried off of a land area and deposited in receiving water. Soil erosion and sediment control is
not a new technology. Many sediment control BMPs already are an integral part of mining and
reclamation operations and do not require additional engineering designs or construction. For
this reason, implementation can require minimal additional labor and the use of conventional
equipment and materials that already are on site and operational. Most BMPs are adaptable to all
regions of the country, with the exception of extremely arid regions of the West (Montana DEQ,
1996). In these regions, conventional BMP designs may need to be refined to account for high
evaporation rates, and new or modified BMP options should be explored. The USDA Soil
Conservation Service and a number of state and local agencies have been developing and
promoting the use of sediment control technologies for years (EPA, 1992).
Design and application of erosion and sedimentation control technology has improved
since the passage of SMCRA and since EPA's promulgation of technology-base_d numerical
effluent limits. Extensive monitoring and case studies have been performed on arid and semiarid
lands to characterize the nature and extent of erosion occurring within these areas. Computer
sedimentation modeling of arid and semiarid fluvial systems has advanced significantly, evolving
into site-specific models that are sensitive to the highly variable environmental factors found
within the region. Designers and manufacturers of erosion and sedimentation control products
have also contributed significantly to the improvement of BMPs. Manufacturers are providing
improved and innovative products capable of addressing generic and specific sediment and
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erosion control problems. Advanced computer prediction models, comprehensive environmental
erosion and sediment management practices, and new erosion control materials and equipment
form the core of the BMPs that may more appropriately address sedimentation in arid and
semiarid coal mining regions.
Using BMP systems designed to address site-specific erosion and sedimentation concerns
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using current modeling techniques, it is now possible to effectively control erosion and sediment
transport, while concurrently minimizing disruption of the fluvial balance. Allowing runoff to
"flow naturally" from disturbed and reclaimed areas is environmentally and socially preferable to
non-consumptive retention in sedimentation ponds that is accompanied by episodic releases of
runoff resulting in sediment imbalances that are potentially disruptive to watershed fluvial
morphology.
In summary, BMPs may be either short-term or long-term in their effectiveness. Methods
and practices that are capable of harvesting and conserving moisture, limiting soil detachment
and erosion, or accomplishing both simultaneously with reasonable economic expenditures find
ready acceptance and wide use throughout the mining industry (Western Coal Mining Work
Group, 1999a). Many types of erosion and sediment control BMPs and methods are currently
used by the coal mining industry within reclaimed areas, serving to reduce the total sediment
impoundment volume required to treat runoff to numerical effluent standards. Increased focus
on the implemention of site-specific sediment control BMPs serves to address sediment at the
source, enhance vegetation growth and stabilize reclaimed lands.
BMPs can be categorized into two descriptive types, either Managerial-or Structural.
These may vary over the life of the disturbance or reclamation period, depending upon changing
site conditions. The characteristics and components of each type of BMP are presented in greater
detail in Sections 3.3.1 and 3.3.2.
3.3.1 Managerial BMPs
Managerial sediment control BMPs include project design and planning methods used to
protect water quality and minimize erosion and sedimentation. Managerial BMPs are employed
prior to, during, and following reclamation of a site. Managerial methods that may be employed
at a site are listed in Table 3b.
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Table 3b: Examples of Managerial Sediment and Erosion Control Practices (Western
Coal Mining Work Group, 1999a)
Managerial Sediment
Minimizing the Area of
Disturbance
Appropriate Application
Timely Placement
Control Sediment at Source
Contemporaneous
Reclamation
Periodic Inspection,
Maintenance and
Replacement
Implementation Technique
Surface disturbances are minimized to that specific area necessary to
conduct the mining and reclamation.
BMPs are judiciously used based on erosion and sedimentation
control capabilities, site-specific environmental conditions, and
sedimentation predictions.
Structures are placed at the most appropriate time to function
properly and effectively during their anticipated use period.
BMPs are implemented at the source of sediment. Terraces, check
dams, straw bales, riprap, mulch, silt fences, etc. are implemented to
control overland flow, trap sediment in runoff or protect the disturbed
land surface from erosion.
After mineral extraction is complete, disturbed areas are reclaimed as
rapidly as is practicable and rehabilitated for the designated post-
mining land use.
BMPs are periodically inspected during construction and use. Based on
these inspections, maintenance is scheduled and adequately performed.
When structures can no longer be reasonably maintained, they are
replaced if necessary. When BMP structures are no longer needed, they
are removed, if necessary, and the disturbed area reclaimed. Most
BMPs are installed as integral components of the surface drainage
system and their removal is not needed.
5.3.2 Structural BMPs
\
Structural BMPs are the physical structures, methods, practices, and products
implemented and used to achieve erosion and sedimentation control. These BMPs are combined
with managerial practices and monitoring plans to form complete BMP systems for a given site.
Structural sediment control BMPs primarily include regrading, revegetation, sediment trapping,
and control of surface runoff. Examples of common structural sediment control BMPs are listed
in Table 3c. EPA recognizes that Table 3c is not inclusive of all sediment control BMPs that are
appropriate for use in arid and semiarid regions. Numerous additional BMPs and BMP
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combinations currently exist and are being used effectively.
Table 3c: Examples of Structural Best Management Practices (Western Coal Mining
Work Group, 1999a, Carlson, 1995, Bonine, 1995, Toy and Foster, 1998, U.S.
Mining and Reclamation Council of America, 1985)
BMP
Straw Bales
Terraces or Benches
Deep Ripping
Contour Berms
V
Diversion Channels
Check Dams
Interceptor Ditch -
Slope Drain
(Contour Ditch)
Mulch
Mulch Crimping
Sediment Control Characteristics And Design Techniques
Inhibit surface runoff and stop the movement of sediment. Bales are used
across medium slopes or at the toes of steep slopes.
Reduce slope lengths and water velocities and increase infiltration.
Constructed as wide (10-20') horizontal, level or slightly reverse sloping steps
in intervals down the slope on or near contours.
Breaks compacted layers, heavy clays, and soil-minesoil interfaces. Increases
infiltration and reduces flow velocities. Ripping loosens and mixes subsoil and
allows root penetration and subsurface water storage.
Control or divert surface runoff flow. Care must be taken to assure a level top
surface with no low spots where breaching could occur. Berm height varies
from one to three feet. Berms that will be in existence for longer than one year
are vegetated to reduce erosion.
Convey runoff from points of concentration across, through, along, and around
areas to be protected. Designed for peak flows based upon a 10-year, 24-hour
storm event. Typically two feet deep with a run-to-rise ration of 3:1. Those in
existence for longer than one year are vegetated to reduce erosion.
Stabilize channel grades and control channel head cutting. Reduce or prevent
excessive erosion by reducing velocities in diversions, conveyances and
sedimentation pond inlets or by providing partial channel sections or structures
that can withstand high flow velocities. Dam height is dictated by flow
amount, channel slope, and available cross sectional area. Sized to pass 10-
year, 24-hour runoff event.
Ditches are placed horizontally at vertical intervals on long slopes to reduce
the effective slope length, slow runoff, reduce erosion and enhance sediment
deposition. They are generally 1.5 feet deep with a run-to-rise ration of 2:1.
Ditches are spaced approximately 50 feet apart horizontally.
Temporary soil stabilization. Used to increase infiltration, retain water, add
surface roughness, decrease runoff, protect soil surface from erosive action of
raindrops, and to enhance seedbed for vegetative growth. When used together
with seeding or planting, mulching can aid in plant growth by holding the
seeds, fertilizers, and topsoil in place. Helps to retain moisture and insulate
against extreme temperatures. In general, higher mulch application rates
(Ibs/acre) are needed for western regions.
Increases the effectiveness of mulch against surface erosion by water and
wind. It is accomplished by tacking mulch materials into the soil surface using
blunt or notched disks that are forced into the soil.
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BMP
Geotextiles
Roughened Surface -
Control Discing
Pitting
Sediment Traps
Contour Plowing
Complex Slope
Drainage to Pit
Cover Crop
Regrading
Livestock Grazing
Irrigation
Landscape
Configuration
Revegetation
Toe Drain Ditches
Sediment Control Characteristics And Design Techniques
Geotextiles, when used alone, can be used as matting to stabilize runoff flow.
Geotextile matting also can be used on recently planted slopes to protect
seedlings until they become established or as a separator between riprap and
soil.
Increases infiltration. Surface roughening is commonly accomplished through
the use of agricultural techniques including discing, plowing, contour
furrowing, and land imprinting.
A mechanical treatment measure which creates small, basin like depressions
that increase surface water revegetation potential of a site. Pitting as a water
conservation and erosion control measure is used on mined lands before
seeding and planting. The method has been used mainly in arid or semiarid
regions where the water conservancy methods are most critical.
Provide small storage or detention areas without special inlet or outlet
controls. Constructed by excavation, or by creating an impoundment with logs,
silt fence or brush barrier/filter cloth as a low head dam.
Prevents rill formation. Furrows formed by contour plowing also add
roughness and enhance infiltration.
Slopes graded with three segments: upper convex, middle straight, lower
concave. Straight slopes are minimized and concave slope is maximized to
reduce erosion and promote deposition on the lower slope segment.
Runoff from disturbed areas drains either directly to or is diverted to the pit.
This water evaporates or is pumped to holding ponds. Holding pond water is
discharged in accordance with NPDES requirements.
Broadcast or drill seeded. Establishes quick live cover & root system. Stubble
acts as surface roughness during winter.
Regrading to approximate original contour or other acceptable slope gradients
and configurations can substantially reduce soil loss rates. Although the
construction of complex or concave hill slope profiles offer grading
challenges, these shapes can substantially reduce soil loss rates.
Controlled livestock grazing can have positive sediment control impacts on
reclaimed areas, such as increasing vegetation cover and production, creating
surface roughening, promoting soil formation, and increasing soil microbial
populations, all of which serve to control erosion and sedimentation. It is
important to have established vegetative cover prior to allowing grazing on
reclaimed land.
If there is not enough rainfall on the area for establishing vegetation, the area
can be irrigated.
Establishes reclaimed topography that is stable with surrounding terrain and
climate. Configuration measures include shorter slopes, complex slopes, and
proper drainage profiles.
Adds soil stability and surface roughness, reduces rainfall erosion, and
physically secures soil making it less erosive.
Store or divert slope runoff. These channels are open, of any cross sectional
shape and are constructed at the toe of exposed slope surfaces.
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3.3.3 BMP Implementation
Selection of sediment control BMPs for mining or reclamation activities should be based
on site-specific conditions. The BMP plan should be designed to: minimize the amount of
disturbed soil, control runoff flowing across a site, remove excess sediment from onsite.runoff
before it leaves the site, and meet or exceed local or state requirements for sediment and erosion
control plans. In most situations, a combination of BMPs is necessary to adequately control
sediment and erosion. Moreover, these BMPs must be properly designed, implemented and
maintained in order to be effective. Implementation of managerial practices and structural
sediment control BMPs, either in addition or as an alternative to sedimentation ponds, should be
expected to:
• Maintain adequate "natural sediment loading" to avoid disruption of the fluvial system,
while preventing impacts to environmental and biologic resources in watersheds affected
. by mining;
• Minimize reductions in downstream runoff;
• Reduce unnecessary additional disturbance of surface acreage; and
• Restore or improve riparian and natural vegetative species.
Appropriate alternative sediment control BMPs can be designed and implemented using
site-specific design evaluations of the various disturbance activities anticipated over the life of
the mining or reclamation operation. BMPs may be used singly or in combination to effectively
control and minimize erosion and sedimentation from disturbed areas.
BMP plans should consider the background environmental conditions (i.e., size of site,
soil types, drainage pattern, rainfall data, receiving channels, and land use) to establish
reasonable and acceptable implementation and monitoring design criteria. The design should
include modeling of disturbance phases to determine the control and treatment practices and
methods to be used to ensure compliance with the site-specific performance-based standards
during the various disturbance and reclamation phases. BMP designs should demonstrate that
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erosion will be controlled, deepening or enlargement of stream channels will be prevented,
disturbance of the hydrologic balance will be minimal, and additional contributions of sediment
of stream flow and runoff outside the permit area will be prevented to the greatest extent
possible. BMP design, construction, implementation, and monitoring represent the complete
BMP system for a given location.
The key to the effective planning and implementation of a BMP system is deployment
flexibility. For a given situation, there may be several BMP combinations that will adequately
control erosion and sedimentation. The type of BMP that is most effective may also change
through time. For example, during the early stages of establishing vegetation on reclamation
areas, livestock grazing represents a potentially disruptive land use activity. However, once the
vegetation is firmly established, livestock grazing can act as an effective BMP. The operational
preferences of mining companies can result in the design and use of a variety of different
combinations of sediment control practices for essentially similar areas. The critical goal that
must be realized is the adequate control of surface erosion and retention of sediment in order to
meet the site's water quality requirements. The primary purpose of sediment control BMPs is to
control sediment at the source and to minimize erosion caused by wind and water. A sediment
control plan should demonstrate that all exposed or disturbed areas are stabilized to the greatest
extent possible.
Sediment control BMPs can be categorized according to function as follows:
Topographic, Slope Erosion, How Structures, Soil Conservation, and Vegetation. BMPs that fall
within these categories may be universal or limited in their application. For example,
reconstructed drainage channels usually are limited to use within low-lying reclaimed areas,
while permanent vegetation typically is established throughout a reclaimed landscape.
Appropriate sediment control BMPs are designed and implemented using site-specific
evaluations of the various activities anticipated during mining or reclamation operations.
3.3.3.1
Topographic
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In order to prevent unnatural sedimentation, mined land surface areas should be reclaimed
to a grade necessary to control surface water runoff and promote appropriate drainage and
stability. Terrace and bench-type grading can prevent slides and sedimentation while promoting
slope stability. Topographic BMPs include:
Planning post-mining topography using modeling to mimic approximate original contour
or pre-mining natural, background erosion and sedimentation yields;
Designing and implementing a BMP plan that will approximate natural drainage as
closely as possible;
• • Choosing sediment control structures according to review of existing topography, flow
direction and volume, outlet location, and feasibility of construction;
Backfilling and grading to approximate original topography or other acceptable slope
gradients and configurations. Blending disturbed areas into the surrounding terrain; and
• Eliminating unstable areas to the greatest extent possible.
3.3.3.2 Slope Erosion
BMPs that control slope erosion are implemented to stabilize and protect slopes against
surface erosion. Slope surfaces should be mulched, vegetated or otherwise stabilized to
minimize sediment movement, and, on a site-specific basis, to address particular erosion problem
spot's according to need. Construction of terraces, benches, and other grading or drainage control
measures can be utilized to prevent erosion and ensure slope stability. These structures should be
designed to be non-erodible and to carry short-term, periodic flows at non-erosive velocities.
These BMPs often help stabilize steeply sloped areas until vegetation can be established. BMPs
that serve to control erosion and sedimentation from slopes include:
Limiting slope length according to modeling prediction of surface runoff sediment yield;
• Creating slope shapes which promote stability through protective surface configurations
(concave vs. convex, simple vs. complex);
• Providing non-erosive mulches or surface cover materials (e.g., durable rock fills that
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limit erosion through adequate surface protection); and
• Segmentation of slopes through construction of terraces or benches to limit slope length
and provide protected drainage.
Flow Structures
Hydrologic flow structures are implemented to ensure that additional contributions of
I
sediment to stream flow and to runoff outside the permit area are prevented to the greatest extent
possible. These BMPs are implemented to direct runoff away from exposed or unstable surface
areas, to control runoff volume and velocity, and to provide water for establishment of vegetative
cover. These structures should be inspected regularly, compacted according to applicable
standards, and maintained properly to ensure maximum effectiveness. BMPs that utilize flow
structures include:
• Implementing diversions, reclaimed channels, drains, terrace drains, down-drains, and
ditches capable of conveying surface water runoff from designated worst-case storm
events and worst-case watershed disturbance conditions around, through or from the
disturbed/reclaimed area;
• Implementing flow structures in a manner that reduces runoff flow velocity and thus
reduces loosening or removal of soil particles; and
j
• Designing flow structures with adequate sizing, configuration and protective linings to
provide stable watercourses for anticipated flow volumes and velocities.
3.3.3.4
Soil Conservation
BMPs that are implemented to conserve soil tend to protect exposed surfaces against the
erosive effects of wind and water by manipulating the soil surface or providing surface cover
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amendments. A sediment control BMP plan should demonstrate that all exposed or disturbed
areas are stabilized to the greatest extent possible, as quickly as possible following disturbance.
Surface erosion protection practices and materials include:
• Mulching with organic or inorganic materials or applying geotextile fabrics;
• Preserving existing vegetation;
• Establishing quick-growing cover crops with annual or perennial plant species; and
• Roughening exposed surfaces. Surface roughening is commonly accomplished through
the use of agricultural techniques including discing, plowing, and contour furrowing.
3.3.3.5 Vegetation
Land in arid and semiarid climates tends to have relatively low vegetation cover and
productivity, particularly where annual rainfall is less than 9 inches per year. Total vegetation
cover values frequently fall within the range of 5 to 20 percent. Yearly vegetation production
tends to be low, with most reclaimed areas producing between 500 to 1,000 pounds per acre
annually (Western Coal Mining Work Group, 1999a).
Preserving existing vegetation or vegetating disturbed soil as soon as possible after
surface disturbance is the most effective way to control erosion (U.S. EPA, 1992). A vegetative
cover reduces erosion potential by: (1) shielding the surface from the direct erosive impact of
raindrops, (2) reducing sediment runoff to downstream areas, (3) filtering sediment, (4)
improving the soil's water storage capacity, (5) slowing runoff and allowing sediment to drop out
or deposit, and (6) physically holding the soil in place.
Establishment of vegetation can be a short-term (temporary) or long-term (permanent)
method for controlling erosion and sedimentation. Plant species are selected based upon land
use, growth conditions, and environmental requirements. Temporary seeding should take place
as soon as practicable after the most recent land disturbing activity. In arid and semiarid regions
where the climate prevents fast growth, temporary seeding may not be effective (U.S.EPA,
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1992). In these regions, mulching may be more appropriate for short-term stabilization.
Common goals for permanent vegetation include the establishment of adequate cover,
production, and diversity to support designated post-mining land use(s), and to protect the soil
from excessive surface erosion. Proper seedbed preparation, the use of high-quality seeds, and
the application of mulch may be necessary for effective erosion control. In arid and semiarid
regions, irrigation and the addition of topsoil or other soil amendments may be required to make
conditions more suitable for plant growth. Although the use of native species is recommended,
both non-native and native plant species may be used for routine and specialized seeding and
i
transplanting programs. Bioengineering or specialized plantings may be used singly or in
combination with hard structures to achieve erosion control and protect and enhance the effective
life of critical erosion and sedimentation control structures or features.
Seed mixtures are an integral component of a BMP reclamation plan and are an important
component in vegetative success. A diverse seed mixture, coupled with appropriate water
management, accelerates early plant community development and diversity. Mixtures and
application rates dramatically influence vegetation germination, establishment.and development.
Land use can have a dramatic effect on a reclaimed area's vegetation characteristics.
Reclamation land use in the arid and semiarid western United States is primarily rangeland with
livestock grazing normally a part of the post-mining land use. Controlled grazing can be used
effectively to promote vegetation growth and development, soil stability and surface water ;
hydrology. Livestock grazing has been successfully used as part of BMP systems to increase
vegetation density on most western coal mine reclamation areas.
3.4 Prediction Models for BMP Design and Implementation
The major factors affecting soil erosion are soil characteristics, climate, rainfall intensity
and duration, vegetation or other surface cover, and topography. Understanding the factors that
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affect erosion makes it possible to predict the extent and consequences of onsite erosion (U.S.
EPA, 1992). Although an estimate of sediment erosion and deposition can be derived over time
using water samples or sediment accumulation markers, this method of erosion prediction can be
time consuming and labor intensive. Prior to implementation of sediment control BMPs, it is
important to determine both the quantity of sedimentation and the sedimentation patterns that can
be expected. Sites should be assessed to determine pre-mining drainage patterns and topography,
to quantify effects of storm runoff and the yield of coarse- and fine-grained sediment, and to
determine morphologic evolution of streams, washes, and arroyos.
Although an estimate of sediment erosion and deposition can be derived over time using
water samples or sediment accumulation markers, these methods of erosion prediction are time
consuming and often labor intensive. The collection of sufficient soil-loss data from natural
rainfall events on erosion plots to permit confidence in the results of statistical analyses has
proven to be a long-term, expensive, and inefficient undertaking (Toy, 1998). Sediment transport
can be predicted with reasonable accuracy using computer models developed for this purpose
during the last 20 years.
Computer models have been developed to assess and predict erosion, soil loss, and
sediment yields from undisturbed lands experiencing overland flow, from lands undergoing
disturbances, and from newly established or reclaimed lands. Computer models are commonly
used to evaluate watershed response and assess impacts of land use and are capable of
determining the effectiveness of BMPs on erosion control and sediment production prior to field
use. These models are particularly valuable in arid and semiarid areas because the infrequency of
precipitation discourages compilation of data from instrumented watersheds. When calibrated,
the models provide a means for comparing sediment loss under undisturbed (premine) and
reclaimed mine land conditions (Peterson, 1995). Examples of soil loss prediction models
include:
SEDCAD 4.0
RUSLE
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EASI \
SEDIMOT n
MULTSED
The efficiency and accuracy of these models has improved dramatically as extensive
environmental databases and product specifications have been developed. A great deal of study
has been performed regarding mined land and new erosion and sedimentation control and
treatment products, to develop and verify these modeling programs. Most importantly, the
models provide a constant base from which to evaluate pre-mining and post-mining sediment
delivery (Peterson, 1995). Computer simulations allow mine operators to determine which
combination of managerial and/or structural BMPs will be most effective at controlling sediment
and erosion at a specific mining or reclamation site.
3.4.1 Revised Universal Soil Loss Equation (RUSLE)
The Universal Soil Loss Equation (USLE) developed in 1961, was designed to predict
average annual soil loss caused by sheet and rill erosion. The USLE can estimate long-term
annual soil loss and guide conservationists on proper cropping, management, and conservation
practices, but it can not be applied to a specific year or a specific storm event. USLE was
modified as the Modified Universal Soil Loss Equation (MUSLE) to replace USLE's rainfall
factor with a runoff factor. The MUSLE model assumes that sediment yield is related to peak
discharge and runoff volume.
The Revised Universal Soil Loss Equation (RUSLE), based extensively on the USLE
model and its data, was developed to estimate average annual soil loss in larger, steeply sloped
areas and can accommodate undisturbed soil, spoil, and soil-substitute material, percent cover,
random surface roughness, mulches, vegetation types, mechanical equipment effects on soil
roughness, hill-slope shape, and surface manipulation. RUSLE is applicable to sheet and rill
detachment only, and does not estimate gully or stream-channel erosion or compute deposition.
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RUSLE is based on a set of equations that estimate annual soil loss (soil removed from
the hillslope or hillslope segment). It was derived from the theory of erosion processes, more
than 10,000 plot-years of data from natural rainfall plots, and numerous rainfall-simulation plots.
RUSLE retains the structure of USLE (Pennsylvania Department of Environmental Protection,
1999, Renard, 1997) and takes the form of the following equation (Toy, 1998).
A = RKLSCP
Where:
A = Computed Soil Loss (Annual Soil Loss as tons/acre/year)
R = Climatic Erosivity or Rainfall erosion index - a measure of the erosive force and
intensity of a specific rainfall or the normal yearly rainfall for specific climatic
regions
K = Soil Erodibility Factor - Ability of soils to resist erosive energy of rain. A
measure of the erosion potential for a specific soil type based on inherent
physical properties (particle size, organic matter, aggregate stability,
permeability). Soils with a K value of 0.17 or less are considered slightly
erodible, and those with a K value of 0.45 or higher are highly erodible. Soils in
disturbed areas can be more easily eroded regardless of the listed K value for the
soil type because the structure has been changed.
I
LS = Steepness Factor - Combination factor for slope length and gradient
C = Cover and Management Factor - Type of vegetation and cover. The ratio of soil
loss from a field with specific cropping relative to that from the fallow condition
on which the factor K is evaluated.
P = Support Practice - Erosion control practice factor, the ratio of soil loss under
specified management practices.
3.4.2 SEDCAD
SEDCAD is a comprehensive model that enables the user to evaluate the performance of
erosion and sediment controls. SEDCAD calculates the amount of runoff and sediment
generated in response to a given precipitation event for specific soil and vegetative cover
conditions, analyzes the effectiveness of sediment/erosion control structures in meeting effluent
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standards, and allows the design of cost effective sediment erosion control structures. SEDCAD
is widely used throughout the mining industry and is the program used by the OSMRE to review
mine permits, and to design and evaluate structure performance in OSMRE's Abandoned Mine
Land Program.
SEDCAD is a hydrology and sedimentology routing model used to simulate peak flows,
drainage volumes, and sediment yields from undisturbed and disturbed/reclaimed watersheds. ;
Hydrograph development and peak flow determination are based on user inputs of a design storm
(e.g., rainfall amount and duration and selection of a rainfall distribution). Hydrographs are
developed on a subwatershed basis with the input area, time of concentration, Natural Resources
Conservation Service (NRCS) curve number, and selection of one of three dimensionless double
triangle unit hydrographs. Routing of hydrographs is accomplished by Muskingum's method
(Warner and Schwab, 1998).
The sediment yield and concentrations of TSS and SS are also determined on a
subwatershed basis. SEDCAD uses a subroutine that implements a method similar to RUSLE to
determine average annual sediment yield. SEDCAD sedimentology input values may be taken
directly from RUSLE results, allowing the two models to work in tandem. Sediment routing is
determined in conjunction with runoff hydrograph routing, and considers the eroded particle size
distributions of the soils exposed to rainfall and runoff. An example of combining RUSLE and
SEDCAD computer models to determine background sediment yield and predict the effects of
sediment controls is presented in Section 5, Case Study 1.
3.4.3 SEDIMOTII
SEDIMOT n considers a number of field parameters (sediment type and concentration,
vegetation type, slope and length of filters) that affect sediment transport and deposition through
filtering materials or vegetation. SEDIMOT n is capable of evaluating the hydraulic and
sediment response of a watershed as well as the effectiveness of detention ponds, grass filters,
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and check dams (Wilson, 1984). Flow is described by the continuity equation and by steady-state
infiltration (i.e., flow decreases linearly from upstream to downstream in the filter). SEDIMOT
n is based on the hydraulics of flow and the transport and deposition profiles of sediment in
laboratory conditions. The model does not handle time dependent infiltration or changes in flow
resulting from sediment deposition during a storm event.
The user of the model divides the drainage basin into subwatersheds of relatively uniform
land use. A hydrograph, sediment graph, and particle size distribution are determined for each
subwatershed, routed downstream, and then combined to form a composite hydrograph, sediment
graph, and particle size distribution. In the hydrologic component of SEDIMOT n, the Soil
Conservation Service (SCS) curve number method is used to determine rainfall excess, the unit
hydrograph theory is used to calculate a runoff hydrograph, and the Muskingum procedure is
used for channel routing. An example of combining SEDIMOT n and SEDCAD computer
models to determine background sediment yield and design sediment control plans is presented
in Section 5, Case Study 2.
3.4.4HEC-6
The HEC-6, Scour and Deposition in Rivers and Reservoirs model was developed by the
United States Army Corp of Engineers (U.S. Army Corp of Engineers, 1999). It is a
one-dimensional, movable boundary, open channel flow, numerical model. HEC-6 was designed
to simulate and predict changes in river profiles resulting from scour and/or deposition over
moderate time periods (typically years, although applications to single flood events are possible).
HEC-6 calculates water surface and sediment bed surface profiles by computing the interaction
between sediment material in the stream bed and the flowing water-sediment mixture.
HEC-6 simulates the capability of a stream to transport sediment, given the yield from
upstream sources. Prediction of sediment behavior requires that the interactions between the
flow hydraulics, sediment transport, channel roughness, and related changes in boundary
geometry be considered. HEC-6 is designed to incorporate these interactions into the simulation.
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Channel bed elevation changes resulting from net scour or net aggradation are reported after a
I
series of uniform discharges of finite duration have been simulated. In this way, a continuous
hydrograph is simulated by a histogram. HEC-6 can be used to predict the impact of land
manipulation or construction on the river hydraulics, sediment transport rates, and channel
geometry.
3.4.5 MULTSED
The Watershed and Sediment Runoff Simulation Model for Multiple Watersheds
(MULTSED) simulates the sedimentation processes of detachment, transport, and deposition.
MULTSED was developed at Colorado State University with support from EPA and the USDA-
Forest Service. In a 1990 comparison of MULTSED, ANSWERS, KINEROS, PRMS, and
SEDIMOT n, MULTSED was found to be the best overall model for semiarid lands (WET,
1990). |
One of MULTSED's strengths is its simulation of channel processes, which often have a
greater impact than hillside processes in a semiarid environment. MULTSED represents the
watershed as a cascade of planes and channels and simulates channel infiltration, erosion and
deposition in addition to calculating sediment transport by size fraction. Rainfall is input
independently for each plane, and runoff is simulated as a kinematic wave with laminar
characteristics. Channel runoff is simulated as a kinematic wave with finite difference.
3-24
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Section 4.0 Benefits of Sediment Control BMPs
The use of sediment control BMPs as an alternative or in addition to sedimentation ponds
for controlling sediment and erosion in arid and semiarid watersheds, has numerous
environmental and enforcement benefits that are not realized when sediment control is designed
around the implementation of sedimentation ponds alone. This section presents the distinct
advantages provided by implementation of a fully integrated, site-specific, and appropriate
sediment control BMP system.
4.1 Environmental Benefits
The capabilities of sediment control BMP systems that are designed to address
site-specific conditions can expedite improved protection and rehabilitation of local natural and
environmental resources that are potentially impacted by mining and reclamation activities. The
fact that BMP Systems are specifically designed to minimize disruption of fluvial stability,
minimize mine related disturbances, foster sustainable sediment equilibrium, and minimize
potential for catastrophic release events, makes them appropriate for erosion and sedimentation
control at arid and semiarid mine sites.
4.1.1 Source Control
Minimizing erosion and sedimentation problems and treating surface runoff at the source
are distinct advantages that BMP systems have over sedimentation pond treatment technology.
Sediment and erosion control BMP Systems are capable of controlling sediment at its source,
preventing erosion across disturbed areas, and preventing impacts to adjacent undisturbed areas.
Treating erosion and sedimentation at or near the source allows surface water runoff to seek
sediment-content equilibrium throughout the entire watershed. This equilibrium results in the
creation of an acceptable, system-wide dynamic balance between flow volumes and sediment
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transport. Source control is needed to achieve and maintain this balance between sediment
loading from surface water runoff and long-term erosion control after mining and reclamation
activities have been completed. To this end, avoiding the construction and subsequent removal
of sedimentation ponds for sediment treatment purposes and establishing a viable BMP system is
paramount to hydrologic system maintenance and rehabilitation.
4.1.2 Minimizes Disturbance to the Hydrologic Balance
Congressionally mandated regulatory goals require protection of the waters of the United
States and the avoidance or minimization of disruption to the hydrologic balance where surface
coal mining and reclamation activities are conducted. With the implementation of alternative or
additional BMPs, erosion and sediment control is focused on the source which allows surface
water that does not infiltrate to discharge from mining or reclamation areas in a controlled
fashion. Sediment levels in the runoff are allowed to fluctuate with the erosion potential
conditions in the watershed, and are not artificially reduced by large in-channel structures (i.e.,
sedimentation ponds). This approach to the control and release of surface drainage adjusts the
hydrologic system gradually, allowing it to adjust slowly over time. This slow-adjustment
provides system stability and enables the components of the watershed to effectively interact and
maintain the hydrologic balance. By allowing natural sediment flow through the system, the
fluvial balance in the watershed benefits through the establishment of natural erosion processes
that will prevail after mining and reclamation activities have ceased.
i
Exposing the down-drainage system to sudden flushes of drainage following removal of
flow restricting or constricting structures is avoided. Sudden flood events can be very disruptive
to channel morphology. Seasoning channels with a range of flows over a period of time, and
avoiding flash flood events or extended periods of water unavailability, facilitates reclamation.
Problem areas associated with various flow volumes can be identified and corrected. Channel
and hydrologic rehabilitation is nurtured for a period of several years under realistic and natural ;
post-mining flow conditions. The net result can be improved and reclaimed areas with increased;
hydrologic stability and nominal disruption to undisturbed lands adjacent to or downstream from
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the affected areas.
4.1.3 Maintains Natural Sediment Yield
Surface water drainage with sediment concentrations approximating background levels
avoids the accelerated erosion that is associated with and frequently occurs immediately
downstream from points where low sediment content waters are discharged (Western Coal
Mining Work Group, 1999a). Accelerated erosion is disruptive to the existing down-drainage
hydrologic balance. In its more dramatic visible forms, accelerated erosion manifests itself in
head-cutting, increased scouring (channel degradation), mass caving, and bank failures in
receiving channels. In severe cases, this type of erosion may affect tributaries throughout a
portion of or an entire watershed. Establishing sediment yields that approximate natural levels
for the prevailing environmental and hydrologic conditions increases the rehabilitation of
watershed characteristics and provides for increased channel stability.
Water released from sedimentation ponds contains low concentrations of sediment and
usually occurs in flow volumes significantly less than flow volumes that occurred prior to
mining. When discharges from a sedimentation pond occur, the essentially sediment-free water
begins to immediately entrain sediment from the fluvial system below the pond. The small
discharge volumes typically do not have the capacity to transport large amounts of sediment
immediately below the pond, but the discharge can have the potential to accelerate erosion and
degrade the stream channel immediately downstream from the sedimentation pond (Western
Coal Mining Work Group, 1999a). Due to the cumulative nature of this erosion, it can become
visibly apparent during the Phase n reclamation liability and bonding period (i.e., 10+ years).
An additional receiving channel impact may occur due to the alteration of sediment
concentration. A lowering or a raising of sediment concentration in drainage from the
reclamation area watershed can trigger degradation or aggradation of the receiving channel,
respectively. Degradation is possible when sediment concentration is lowered and additional
sediment is entrained by the flow event. Conversely, if drainage from the undisturbed
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watersheds below the sedimentation pond is higher in sediment concentration, the reduction in
lower sediment concentration flow from the reclamation area watershed may trigger aggradation
of the receiving channel. This decrease in entrainment capacity and flow can result in increased
sediment.
Implementation of sediment control BMPs in addition, or as an alternative, to
sedimentation ponds, provides an advantage in allowing drainage to entrain and carry a sediment
load that approaches its energy capacity to do so and that is not artificially adjusted by an
in-stream structure (sedimentation pond) before being released. The result is the prevention of
severe erosion and instability problems directly downstream.
4.1.4 Minimizes Surface Disturbance
The appropriate application of alternative sediment and erosion control BMPs can avoid a
significant amount of unnecessary surface disturbance on western mine; lands. The amount of
land that must be disturbed for construction of sedimentation ponds varies based on site specific
environmental conditions. For example, the number of acres of surface land disturbance
resulting from the use of sedimentation ponds at four coal mine sites in the arid western coal
region are presented in Table 3a, Section 3.2.1. The four mine operations vary significantly in
their use of ponds, from 14 to 149 total ponds that disturb from 36 to 540 acres. The use of BMP
systems would avoid the disturbance of these additional acres.
Under Wyoming's Guideline No. 15, the Jim Bridger Mine uses alternative sediment
control BMPs (e.g., berms, diversion ditches, and small catchments) to manage drainage from
reclaimed areas and has only disturbed 3.9 acres (Western Coal Mining Work Group, 1999b).
The Jim Bridger mine estimates that an additional 200 acres would be disturbed if sedimentation
ponds were used to manage drainage at this site (Western Coal Mining Work Group, 1999a).
The reduction in surface disturbance that may be expected by implementation of sediment
control BMPs as an alternative to sedimentation ponds is significant.
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4.1.5 Encourages Vegetation
A BMP system approach to erosion and sediment control maximizes the land's ability to
harvest or use precipitation which is key to the success of vegetation in the arid and semiarid
western United States. Sediment control has historically focused primarily on the capture of
surface water runoff in sedimentation ponds located on the bottom periphery of the disturbed
area. Surface water runoff captured by sedimentation ponds in the arid and semiarid regions is
typically allowed to evaporate, and is not made available for vegetative growth or soil
conditioning. Sediment control BMP plans encourage the infiltration and retention of
precipitation in the soil where it benefits microbial activity and plant growth. These BMP plans
are designed to maximize the availability of limited precipitation for improving soil and
enhancing vegetation and are critical to the growth and establishment of vegetation and the
development of plant communities. Even small increases in plant cover and associated root mass
can have significant impacts on the stability of reclamation surfaces by reducing flow velocity,
increasing soil cohesiveness, and promoting biological diversity.
4.1.6 Improves Soil and Promotes Soil Conservation
The characteristics of soil are key to successful reclamation. Water management and soil
improvement practices that are inherent to sediment control BMPs can effectively improve soil
moisture availability. Soil characteristics that are critical to the growth and establishment of
vegetation can be readily influenced by these BMPs both temporarily and permanently. BMP
systems promote water infiltration and availability, which increase incorporation of organic
materials capable of improving soil structure, nutrient retention and availability, water infiltration
and harvesting, and long-term plant production and diversity.
Western topsoils are generally poorly developed and tend to be characteristically poor in
nutrients (Western Coal Mining Work Group, 1999a). Ensuring that this valuable resource is
conserved and even improved during reclamation is an important concern. Implementation of
appropriate sediment control BMPs can be expected to conserve and protect this resource by
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controlling overland flow and its associated erosion force, limiting slope lengths, increasing
surface roughness, harvesting precipitation, increasing moisture content, promoting vegetation
diversity, increasing organic matter, improving soil texture, and fostering soil formation
processes. These factors combine to result in improvements to soil characteristics that promote
and encourage stability, soil biota content, cohesiveness, and plant growth. Increases in soil biota
and above ground vegetation in turn promote soil formation and stability.
4.1.7 Addresses Site-Specific Environmental Conditions
The design of sedimentation control plans incorporating appropriate BMPs allows for
sediment control on a site-specific basis, according to a site's environmental conditions and
requirements. Implementation of BMPs that are designed to address specific sedimentation and
erosion concerns, background sediment levels, and hydrologic conditions of a particular site,
allows more appropriate, performance-based sediment criteria to be developed prior to issuance
of permits. Implementation of site-specific, comprehensive sediment and erosion control BMP
plans also allows for consideration of the long-term effects of mining and reclamation operations
and avoids the shock that can be experienced by these watersheds from the implementation and
subsequent removal of water impounding structures (i.e., sedimentation ponds).
4.1.8 Stabilizes Landforms
Topography plays a key role in the long-term surface stability of arid and semiarid
reclamation areas. The primary goal in designing, constructing, and implementing sediment
control BMPs that will determine post-mining topography is to achieve a stable landform. An
appropriate and natural topography created by implementation of BMP plans that consider
site-specific drainage patterns is essential to minimizing erosion rates and encouraging the
growth of vegetation.
BMPs that are implemented to provide appropriate topography increase channel stability,
improve soil moisture availability, foster the creation of shallow perched water tables, encourage
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
increased infiltration of precipitation and drainage into ground water resources and decrease soil
erosion. All of these functions allow the establishment of vegetation within the reconstructed
channels where little or no vegetation existed prior to mining and reclamation operations.
4.1.9 Minimizes Disruptions to Flow Regime and Evapotranspiration Losses
Sedimentation ponds have significant potential for removing runoff from the hydrologic
system., and precluding potential down-drainage uses. With the implementation of alternative
sediment control BMPs, drainage is allowed to flow relatively unimpeded. As a result of the
appropriate implementation of these systems, impacts to downstream water users and to
intermittent or perennial water resources, are minimized or avoided. In addition, the long-term
flow pattern is established early in the reclamation process and sudden impacts to stream
morphology and flow regime experienced after the removal of a sedimentation pond at Phase n
bond release can be prevented. Disruption of the prevailing hydrologic balance in arid and
semiarid regions can be expected to be much greater when the use of sedimentation ponds is
predominant, than when BMPs are used to simulate pre-mining, undisturbed conditions.
BMP systems also avoid the unnecessary impounding of water and associated
evaporation losses. Losses from ponds can be significant in the arid and semiarid west where
evaporation rates are characteristically much higher than the annual precipitation (Western Coal
Mining Work Group, 1999a). Implementation of sediment control BMP plans also serves to
increase the availability of surface and ground water, because water loss is avoided and runoff is
allowed to flow naturally and recharge local downstream resources.
4.2 Implementation and Enforcement Benefits
4.2.1 Implements Existing Requirements
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The Surface Mining Control and Reclamation Act already institutes specific requirements
for surface coal mining and reclamation operations to achieve acceptable reclamation standards.
These performance standards include successful revegetation, approved post-mining land use,
Stabilizing and protecting all surface areas to effectively control erosion, and minimizing
disturbance to the prevailing hydrologic balance while taking into consideration the physical,
climatological, and other characteristics of the site. SMCRA's performance standards require
establishment of an effective, permanent vegetative cover that is at least equal in extent to the
natural vegetation or to that necessary to achieve the approved post-mining land use.
Implementation of a sediment and erosion control BMP plan designed to address
i
site-specific sedimentation issues incorporates and complies with all requirements under
SMCRA, without precluding consideration for local hydrologic balance.
4.2.2 Improves Monitoring and Inspection Capability
Under the existing effluent guidelines, a mine is required to monitor point source
discharges to demonstrate that Settleable Solids (SS) are equal to or less than 0.5 mL/L when
released from reclaimed areas. To meet Phase II bond release requirements, the inflow into
sedimentation ponds must be equal to or better than background and meet all applicable federal,
state, local and tribal laws and regulatory requirements. When these requirements are met, the
operator is eligible to apply for a Phase n bond release for the reclaimed area and terminate the
existing guideline monitoring obligation. With the implementation of alternative or additional
sediment control BMPs, inspection and enforcement compliance monitoring would be improved
dramatically. It would no longer be necessary to wait for a precipitation event to obtain samples
to determine compliance. Alternative sediment control BMPs would allow Phase n bond release
inspection and compliance evaluations to proceed independently of the season of the year or
storm events and on a more frequent basis. The BMP approach uses the inspection of BMP
design, construction, maintenance and operation to demonstrate compliance.
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4.2.3 Provides Control and Treatment Flexibility
Sediment control BMP plans have been and are being successfully implemented. These
BMP plans are highly adaptable to nearly all erosion and sedimentation control situations. This
means that each site's unique and diverse environmental conditions may be considered and
addressed through the implementation of site-specific BMP plans that can be designed and
adjusted to achieve a variety of prioritized goals best suited to the needs of a particular location.
Benefits of Sediment Control BMPs
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Section 5.0
Case Studies
The Western Coal Mining Work Group submitted data and information showing the use
of mine models to determine sedimentation and the use of BMPs at existing mine sites in the arid
and semiarid western coal region. Summaries of submitted information are presented in this
section as three case studies.
5.1 Case Study 1 (Western Coal Mining Work Group, 1999c)
The NMA, as part of the Western Coal Mining Work Group, conducted a study
comparing the performance, costs, and benefits of a single model mine site to meet effluent
limitations as they currently exist at 40 CFR part 434 versus the proposed option where
alternative sediment controls BMPs are used (Western Coal Mining Work Group, 1999c). A
representative model mine in the arid and semiarid western United States was developed for the
comparison, including contour maps and corresponding hydrologic and soil databases typical of
western mines. Original and approximate topography was used to model surface drainage,
sediment yield, and soil loss rates from the affected watersheds. Results from RUSLE and
SEDCAD modeling were generated for the following three scenarios:
1) Pre-mining Undisturbed Watershed - Modeling of the area prior to any surface
preparation, surface disturbance, or mining activities was conducted to characterize
background water quality, soil loss rates, and sediment yield. Data were used to establish
background standards for BMP system control;
2) Post-mining Reclaimed: Existing Guidelines - A sediment pond focused treatment system
was modeled that meets 0.5 mL/L SS at the perimeter outfalls.
3) Post-mining Reclaimed: Sediment Control BMPs - A BMP system focusing on the use of
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
alternate sediment controls was modeled to provide erosion and sediment control for
reclaimed lands seeking to approximate undisturbed background surface drainage
volumes and peaks, TSS and SS concentration, soil loss rates, and sediment yields.
Characteristics of the representative model mine area and information used to perform
performance and cost evaluations are presented in Table 5a.
Table 5a: Representative Mine Characteristics and Model Input Information
Parameter
Input information
Total Acres
Actual Disturbed Acres
Affected Acres
Unaffected Acres
Storm Event
Rainfall
Soil Type
Sediment Control BMPs
# Sedimentation Ponds
Types of Surface Conditions
Computer Model Input Information
(RUSLE)
1,188
381.8
616.7
571.3
10 year - 24 hour
1.8 inches
Sandy clay loam, Loamy sand
Manipulation of topography, gradient bench
terraces, terrace drains, contour furrows,
reclaimed channels, diversion ditches,
establishment of permanent vegetation,
mulching and detention basins. _
3, in series
Undisturbed; Spoil, backfilled and graded,
topdressed, straw mulched and seeded;
Re vegetated, 1-3 years
Revegetated, 4-8 years
Rainfall amount, intensity, frequency and
duration; soil moisture conditions, soil types,
susceptibility to erosion, eroded particle size
distributions, infiltration rates, and soil
permeability; vegetative ground cover and
evapotranspiration rates
The reclamation area within the representative model mine contained the following
surface conditions: areas containing spoil outslopes, and rough and final backfilling and grading,
areas where soil resources are being replaced (including topdressing, contour furrowing,
mulching, and seeding); and areas with 1-3 years of vegetative growth, or with 4-8 years of more
permanent growth. Reclamation area surface conditions also included a final pit undergoing
5-2
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Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
reclamation with the potential for non-process mine drainage to run off the site. This
configuration normally represents peak-sediment-yield potential for a reclaimed area during the
mining and reclamation process. The reclamation area was positioned within a portion of the
watershed, so that drainage from both the reclamation area and the adjacent undisturbed lands
were considered in choosing and developing sediment control strategies.
The alternate sediment control BMPs used during reclamation were:
• manipulation of topography to develop more stable slopes
• earthen terraces and berms
• terrace drains
• contour furrows
• diversion ditches
surface roughening/land imprinting
sediment detention basins
• revegetation
Reclaimed area topography and the extent of area disturbance were held constant in
modeling both reclamation sediment control scenarios. Holding these inputs constant enabled
and facilitated the analysis and comparison of model results for soil loss, surface drainage rates,
surface drainage volumes, and BMP performance.
5.1.1 Modeling Results
The modeling approach used for this study is shown in Figure 5a. The RUSLE 1.06 and
SEDCAD 4.0 models were used to estimate values that characterize site hydrology and
sedimentology.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Figure 5a: Mine Model Approach: A Method for Evaluating Erosion and Sediment
Control Options (Western Coal Mining Work Group, 1999c)
INPUTS
Mine Site Environmental Parameters
Precipitation-Storm Duration and Intensity
SolLCbaracteristics-Texture. Erodibilitv
Antecedent Moisture Content, and
Rate
Vegetation-Effective Ground Cover and
Use/Crop Management
Channel-Cross Section
Configuration and Area, Slope, Length
Gradient, Bed Material Particle Size
and Relative Percentages, Watershed
Acreaae. and Subwatersheds
Mining Operation Characteristics
Pit Dimensions-Dragline.
Annual Production, Depth to Seams,
Intel-burdens
Prestrtepino Dimensions-Dragline. Truck
Shovel, and Soil Salvage
Sediment Control Options
Managerial-BMP System
Operational-Construction and
Structural-Topographic Manipulation,
Stabilization, Flow Modification
Soil Conservation, and Road Drainage
MINE MODELING
Watershed and Mine
Modeling Tools
SEDCAD 4.0
RUSLE 1.06
Pond & Alternate
Control Method Unit
Costs
Environmental Baseline
Information
OUTPUTS
Performance
Sediment Control
Costs
Selected-Sediment
Control Options
Benefit
Environmental Benefits &
Impacts
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Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
5.1.1.1
RUSLE 1.06
Annual average soil loss was predicted for two scenarios with the help of RUSLE version
1.06. The two scenarios were for pre-mining (undisturbed) conditions and for post-mining
(reclaimed with BMPs). The type of input information for the modeling effort is listed in Table
5b and information input values were based on vegetation, soils, and surface configurations
obtained from case study mines and mine permits. Representative data were entered into the
RUSLE program to generate sediment loss values. RUSLE input and output data are presented
in Appendix D, Tables D-l through D-5.
For pre-mining, undisturbed conditions, the predicted weighted average annual soil loss
was 4.7 tons/acre/yr. According to the Western Coal Mining Work Group, this is a reasonable
value for the arid and semiarid coal regions (Western Coal Mining Work Group, 1999c). The
weighted average annual soil loss of the reclaimed mine lands was 3.0 tons/acre/yr. Data
supporting the weighted average soil loss estimates are presented in Appendix D, Table D-6.
The soil loss is slightly lower after reclamation because the BMPs allow for improved infiltration
and retention of storm water, and for the growth and establishment of vegetation. Also,
implementation of BMPs result in landforms that have been reconstructed to facilitate lower
erosion rates and enhanced deposition at down-gradient slope boundaries.
5.1.1.2
SEDCAD 4.0
All sediment and hydrology model results from the mine prior to mining and from the
mine after reclamation using BMPs to control sedimentation are similar, whereas the results for
the area reclaimed to meet the effluent limitations in 40 CFR part 434 are considerably lower
than the pre-mining conditions. The decrease in sediment yield and runoff resulting from
compliance with 40 CFR part 434 limits is expected due to the implementation of sedimentation
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
ponds that meet discharge limits by impounding runoff. To avoid potential adverse impacts on
the hydrologic and sediment balance, and to maintain the stability of the fluvial system, drainage
from the reclamation areas should be as similar to pre-mining drainage as possible. Based on this
standard, implementation of BMPs would be a preferred option. Sediment loss, soil loss, and
surface runoff flow model results for undisturbed conditions, reclamation areas with
sedimentation ponds, and reclamation areas with sediment control BMPs are presented in Table
5b. SEDCAD output for each of the three scenarios is presented in Appendix D.
5.1.2 Cost
The Western Coal Mining Work Group completed an extensive analysis of costs
associated with meeting effluent limitations using sedimentation ponds and implementing BMPs
under a Western Alkaline Coal Mining subcategory. Cost estimating criteria for sedimentation
ponds and BMPs implemented at the model mine were collected from approved mine permit
applications, developed from mine records, and estimated using technical resources and industry
experience. These unit cost data are presented in detail in NMA's Mine Modeling Report
(WCMWG, 1999c).
The model cost assessment was based on capital costs (design, construction, and removal)
and operating costs (inspection, maintenance, and operation) associated with BMPs used over the
anticipated bonding periods. The bond release period for meeting numerical effluent standards in
the arid and semiarid western coal region can be expected to be ten years or longer (Western Coal
Mining Work Group, 1999a, Peterson, 1995). With the implementation of alternative sediment
control BMPs, reclaimed areas may be eligible for Phase n bond release about five years after
they have been successfully revegetated (Western Coal Mining Work Group, 1999a).
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Development Document - Proposed Western Alkaline Coal Mining Subcate
Capital and operating reclamation costs, as estimated by the Western Coal Mining Work
Group, for both the existing effluent guidelines and the proposed subcategory options are
presented in Table 5c. The present value of the reclamation costs over the ten year period
(discounting at seven percent) is $ 1,700,000 for the existing guideline and $ 1,028,000 for the
proposed subcategory, or a present value total savings of $ 672,000 over ten years. This
represents a 39 percent overall reduction in costs, or $1,764 in savings per disturbed acre. The
annualized savings is $ 95,000 (annualized at seven percent), or $ 251 annualized savings per
acre for the 381 reclaimed acres.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Table 5b:
Comparison of Hydrology and Sedimentology Results (modified from
Western Coal Mining Work Group, 1999c)
RUSLE(V 1.06) Modeling Results
Soil Loss (tons/acre/year)
(Weighted Average)
Pre-Mining
Undisturbed
Conditions
Reclaimed to Meet
Numerical
Limitations1'2
Reclaimed Under
Proposed
Subcateeory 3
4.7
NM4
3.0
SEDCAD(V 4.0) Modeling Results
Peak Discharge (cfs)
(10 year, 24-hour storm event)
Total Runoff Volume (acre-feet)
(10 year, 24-hour storm event)
Sediment (tons)
(10 year, 24-hour storm event)
Sediment (tons/acre)
(10 year, 24-hour storm event)
Peak Sediment (mg/L)
(10 year, 24-hour storm event)
Peak Settleable Solids (mL/L)
(10 year, 24-hour storm)
Settleable Solids (mL/L)
(24-hr Volume Weighted)
(10 year, 24-hour storm)
Sediment Yield (acre-feet/year)
f A v(aT*nCTf* A nniifll^
679.09
80.01
7,004.2
5.9
155,091
38.22
17.89
8.3
44.79
48.83
666.1
0.6
28,235
0.00
0.00
O5
601.89
72.93
5,611.1
4.7
114,800
25.86
13.96
6.7
1 Sediment was controlled with sedimentation ponds.
2 Assumes ponds are filled to design storage capacity with 3 years of sediment runoff.
3 Sediment was controlled by alternative sediment control BMPs.
4 Not measured.
5 Assumes no sediment is stored in the ponds, and 3 years of annual sediment runoff.
volume is available. SEDCAD 4.0 uses a subroutine that implements a method similar to RUSLE to determine
average annual sediment yield. SEDCAD sedimentology input values were taken directly from the RUSLE
version 1.06 analysis.
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Development Document - Proposed Western Alkaline Coal Mining Subcatezory
Table 5c: Cost of Existing Guideline Compliance vs. Cost to Implement Alternative
Sediment Control BMPs (adapted and revised from WCMWG, 1999c)
Current Effluent Guideline
Year
Proposed Subcategory
Capital Operating Total
Present
Value1
Capital Operating Total
Present
Value1
1 $975,435 $15,384 $990,819
2 2,720 142,804 145,524
$990,819 $760,816 $3,300 $764,116 $764,116
136,004 43,577 103,368 146,944 137,332
3
4
0
0
190,181
88,956
190,181
88,956
166,112
72,615
0 59,876 59,876 52,298
0 77,895 77,895 63,586
0 14,147 14,147 10,793
26,231
161,999
26,231
161,999
20,011
115,503
15,269
15,269
15,269
15,269
10,175
9,509
0
171,607
133,377
15,269
: 804,739
133,377
186,876
$1,954,501
77,626
101,648
$1,700,021
10
Total (not $1,149,761
discounted)
$804,393 $258,586 $1,062,97 $1,028,124
9
Annualized @ 7% over 10
years
$ 242,045
$ 146,382
Annualized Savings
Annualized Savings per Reclamation Acre
$ 95,663 Present Value Total Savings
$ 251 Present Value Total Savings per Acre
$671,897
$ 1,764
1 Discount Rate: 0.07.
2 Based on 381 disturbed acres.
Costs expressed in 1998 Dollars-
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
5.2 Case Study 2 (Bridger Coal Company, Jim Bridger Mine)
Wyoming Department of Environmental Quality, Land Quality Division Rules and
Regulations, Chapter IV, Section 3g(l) states that exemptions to the use of sedimentation ponds
may be granted where, by the use of alternative sediment control (ASC) measures, mine drainage
will not degrade receiving waters. The Jim Bridger Mine located in southwestern Wyoming, has
successfully used ASC measures, in addition to several sediment ponds, to treat disturbed area
runoff and prevent degradation of local stream water quality since 1984.
II!
Case Study 2 presents a summary of a Jim Bridger Mine study provided by the Western
Coal Mining Work Group (Bridger Coal Company, 1987). Bridger Coal Company began coal
production in 1974. The Bridger mine is located in a desert located 28 miles northeast of Rock
Springs in southwest Wyoming. Mean annual precipitation is 6-8 inches and the mean frost free
period is 100 days. High winds are frequent and evapotranspiration is high. Some soils and
spoils are saline or sodic. The local receiving water consists of ephemeral streams.
An experimental practice for a portion of the mine was initiated in 1983 to test the
effectiveness of ASC techniques compared to sediment ponds for preventing additional
contributions of sediment to receiving streams. The ASC practices became standard in 1987, and
are still in use today. The effectiveness of ASC techniques continues to be monitored.
5.2.1 Justification ofASCs
Initial water quality data available for receiving streams are presented in Figure 5b. The
data indicate that undisturbed mine area runoff is high in suspended solids. Data from single
stage sediment samples show TSS concentrations of 110 to 820,000 mg/L for discharges from 1
to 500 cubic feet per second (cfs). The highest values measured by single stage sediment
samples were enriched in coarse sediment by continued circulation during the runoff event.
However, values of 800,000 mg/L indicate that sediment transport is high.
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Development Document - Proposed Western Alkaline Coal Minins Subcategorv
1,000
100
"o
o>
E>
u
«
o
10
1
10
Figure 5b: Initial Receiving Stream TSS Data
m
A .
m
; a
•
• I
A A x
• X
A
A
+ " . X
1 1 1 1 1 1 1 ' 1 ! 1 1 1 !_!_! ...1 .1 , X ' '
0 1,000 10,000
•
* Mddle Deadman Wash
a Nine One Half Mne Wash
Gauge
A Ten Mle Draw Trib.
• Nine Mle Wash
X Nne One Half Mle Wash
Above Rt
100,000 1,000,000
Total Suspended Solids (mg/L)
Logistical concerns regarding sediment ponds were important in the decision to
implement ASC techniques. The extensive mining area and the drainage density would
necessitate approximately 200 ponds to control all mining disturbed runoff over the life of the
mine. This would entail disturbing over 400 additional acres. Such land disturbance is
essentially eliminated by use of ASC techniques.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
The benefits of the use of ASCs instead of sediment ponds are:
• Channel degradation below dams, produced by the discharge of
unnaturally clear and erosive water, is precluded;
t
• Additional disturbance due to dam and pond construction is avoided; and
• With the elimination of impoundment storage time, seepage, and
evaporation, there is less disruption of natural stream flows.
5.2.2 Description ofASC Techniques
Several techniques are used by the Bridger Coal Company to limit sediment discharge
from mined land to background levels (Hargis, 1995). Most of these techniques are appropriate
for small drainage areas. Drainage from larger areas can be diverted to the pit floor where it can
be stored and used for road watering. The first group of techniques involves preventing the runoff
from leaving the disturbed areas. These techniques include:
• berms
• diversion ditches
• toe ditches
• small catchments
• drainage to pit floor via haul roads and ramps .
The second group of techniques involves the use of rock check dams or hay bales for the
purpose of filtering and temporarily detaining runoff water until some of its sediment load settles.
Check dam size is determined by using the SEDIMOT n computer program. These materials are
used a short distance downstream from the disturbed land. They are installed before soil removal
and maintained while the disturbed drainage area is unstable.
A third group of techniques involves appropriate mine land reclamation practices and includes:
• prudent geomorphic design
• reconstruction of complex slopes
• restoration of drainage density
• roughening of soil surface
• mulching
• contour farming
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
• timely establishment of permanent vegetative cover
Bridger Coal Company continuously evaluates the effectiveness of sediment control
technologies that are in place at this site as well as the predicted effectiveness of additional
techniques, and modifies the ASC plan appropriately when necessary.
5.2.3 ASC Design
In order to determine the most appropriate ASC techniques for each mining area, Bridger
Coal Co. used the computer models SEDIMOT E and SEDCAD. These models allow evaluation
of disturbed area runoff prior to the disturbance and simulate the various ASCs. These models
also allow the determination of ASC size and location necessary to reduce the sediment
discharge to levels below the receiving stream water quality. Once an ASC plan has been
designed and implemented, a monitoring program is then used to determine the effectiveness of
the control techniques and record water quality degradation, should any occur.
Prior to the original permit application at this site, surface water quality data showed that
TSS was the only parameter that was consistently high, and was, therefore, of concern to in
stream water quality. This data is presented in Table 5d. For this reason, and because of the
importance of sediment transport in fluvial systems, TSS is the primary water quality parameter
considered in design of ASC techniques.
Table 5d: Premining Surface Water Quality Data
Site
BCTR
BCTR
L10MD
L10MD
MDW
Type
PD
PD
SC
SC
SC
Date
04/14/80
05/15/80
01/17/80
04/14/80
06/17/80
Iron
(mg/L)
1.47
1.32
1.42
0.52
475.00
Manganese
(mg/L)
0.044
0.048
0.190
0.033
7.600
Field pH
7.20
9.00
-
-
-
TSS
(mg/L)
411.0
303.0
182.0
1240.0
21750.0
Discharge
(cfs)
_
-
-
_
-
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Site
MOW
MOW
UDW
U10MD
U10MD
U10MD
U10MD
U10MD
U10MD
U10MD
10MDT
10MDT
10MDT
10MDT
10MR3
10MR3
10MR3
10MR3
10MR3
10MR3
10MR3
10MR3
10MR3
10MR3
10MR3
10MR4
10MR4
10MR4
10MR4
Type
SC
SS
ss
SC
SC
SC
SC
SC
SC
ss
SC
SC
ss
ss
PD
PD
PD
PD
PD
PD
PD
PD
PD
PD
PD
PD
PD
PD
PD
Date
05/14/80
06/17/80
03/17/80
04/26/79
05/31/79
08/22/79
10/24/79
03/11/80
04/14/80
03/19/81
04/16/80
06/17/80
03/13/80
04/16/80
04/26/79
08/22/79
09/25/79
04/16/80
05/15/80
06/18/80
07/10/80
08/04/80
09/05/80
10/02/80
11/06/80
04/26/79
08/22/79
09/25/79
10/24/79
Iron
(mg/L)
1.08
475.00
1.15
0.55
0.47
4.76
0.06
0.16
0.21
1.24
2.78
165.00
164.00
180.65
2.40
23.60
32.00
0.56
0.50
4.12
1.27
3.04
4.20
1.42
3.15
31.00
16.00
1.67
1.59
Manganese
(mg/L)
0.449
7.600
0.430
0.180
0.050
0.120
-
0.064
0.029
0.190
0.090
3.200
2.100
2.715
0.050
0.260
0.440
0.210
0.200
0.075
0.130
0.385
0.410
0.020
0.332
0.370
0.190
0.270
0.000
Field pH
-
-
7.80
-
8.40
7.30
8.00
7.70
8.30
-
-
-
.
"
7.80
8.20
6.00
8.80
7.30
7.90
7.50
7.20
7.40
8.30
8.75
•
7.80
6.20
7.40
TSS
(mg/L)
66152.0
21750.0
1672.0
24.0
40.0
79.0
52.0
68.0
916.0
56.0
8728.0
8141.0
1532.0
8728.0
68.0
275.0
816.0
71.0
418.0
37.0
65.0
180.0
368.0
438.0
-
620.0
348.0
30.0
36.0
Discharge
(cfs)
-
-
-
-
-
-
-
-
-
-
-
18.0
28.0
1.0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Site
10MR4
10MR4
10MR4
9.5MD
9.5MD
9.5MW
9.5MW
9MW
9MW
9MW
9MW
Type
PD
SC
ss
ss
ss
SC
ss
ss
ss
ss
ss
Date
04/14/80
05/15/80
06/18/80
04/15/80
08/22/79
07/29/81
09/15/81
06/17/80
08/21/79
03/08/80
07/15/81
Iron
(mg/L)
0.47
0.46
55.50
0.34
1470.00
936.00
930.00
140.00
520.00
42.20
1050.00
Manganese
(mg/L)
0.120
0.210
1.570
0.450
22.100
-
-
3.500
12.100
0.920
-
Field pH
7.40
7.50
6.80
-
-
-
-
-
-
-
-
TSS
(mg/L)
19.5
715.0
1700.0
4516.0
3211.0
61600.0
38700.0
11660.0
5373.0
1768.0
93600.0
Discharge
(cfs)
-
-
-
-
-
72.0
104.0
-
-
19.7
-
PD = Pond; SC = Stream Channels; and SS = Sediment Sampling Stations.
In the SEDIMOT H and SEDCAD models, the SCS curve number is used for flow runoff
calculations; the Modified Universal Soil Loss Equation (MUSLE) is used for soil loss
calculations; the Muskingum method is used to route water flow; Williams Model I is used to
route sediment in channels; and Yang's unit stream power equation is used to route sediment
overland. Application of these models allows increased temporal and spatial variability to be
incorporated into the analysis, and allows for channel segments and subwatershed areas to be
specified to simulate individual contributions to the total basin output.
For this site, a database containing TSS concentrations in a small ephemeral stream
during pre-mining, undisturbed conditions existed prior to the initial ASC application submittal.
Data from this database are presented in Table 5e. From this database, a design TSS input value
for the SEDIMOT D/SEDCAD simulations was calculated. The arithmetic average of these data
(30,000 mg/L) was used as a design criterion to determine the location and size of the ASC
structures. Preferably, disturbed area runoff should be near or below the mean TSS concentration
of the observed data (30,000 mg/L). The actual impact of the mine runoff on the receiving
stream water quality was determined from the data collected from the ASC monitoring program.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Table 5e: Existing Database, Undisturbed TSS Concentration Data
Location
Nine Mile Wash
9.5 Mile Wash @ Crest Gage
Middle Deadman Wash
9.5 Mile Wash @ Temp.
Recording Sta.
Date
08/21/79
03/08/80
10/05/80
10/05/80
07/15/81 '
08/09/82
08/22/79
07/29/81
09/15/81
08/05/82
5/14/80
06/17/80
09/14/82
9/24/82
TSS
(mg/L)
5.373 0
1 768 0
37 700 0
22.640 0
93.6000
34 050 0
3,211.0
61.600.0
38.700.0
95.700.0
66,152.0
21.750.0
53,540.0
44.500.0
42.920 0
34.660.0
32.780 0
29.420.0
3.1550
17.0000
20.300.0
15.540.0
24.840.0
20.490 0
17.1500
19.9000
16.120.0
20.020.0
14.670.0
13.3400
36.860.0
8.160.0
14.800.0
Peak
Monthly Flow (cfs)
13 0
354
504
504
120
55.0
375.0
720
1040
1 20 0
5.0
8.0
27.0
280
22 0
11 0
40
1 0
NA1
NA1
MA1
NA1
NTA'
NA1
NA1
NA1
NA1
NA1
NA1
NA1
NA1
NA1
NA1
Average = 29.770 (Round to 30 000)
10-Yr.-24-hr.
Peak Discharge (cfs)
1,646.0
625.0
887.0
-
Not available, hydrograph not recorded.
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Development Document - Proposed Western Alkaline Coal Mining Subcate
The actual ASCs selected differ for each reclaimed area and are determined by site
specific analysis. As part of this analysis, the company uses SEDIMOT H/SEDCAD to model
the effects of seven ASC techniques, simulated in sequence as presented in Table 5f. The
sequence is determined by experience with ASC effectiveness in reducing sediment discharges.
Table 5f : Order of Simulation of Sediment Control Best Management Practices
Order of Implementation in Design
1
2
3
4
5
6
7
Sediment Control Technique
Rock Check Dams
Interceptor Ditch (Contour Ditch)
Contour Berms
Vegetative Buffer Strip
Toe Drain Ditch
Temporary Barrier
Benches
5.2.4 Monitoring Program
Monitoring is conducted during runoff events between May 1 and September 30 (when
temperatures are above freezing). Each monitoring station is serviced generally after each storm,
and at least once per month, from May through September. In addition, checks are performed
every two weeks from May through September.
Through the first three mining periods, eight paired watersheds (four pairs) and one
control station were equipped with automatic pump samplers and manometers. Each watershed
pair consisted of one disturbed watershed treated with ASCs and an undisturbed watershed. The
nine sampling stations were:
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
111 !i
SWPS-2 Station SWPS-2 was a control watershed location on a tributary of Deadman
Wash. This station was impacted by mining in 1990 and decommissioned in
1991. However, no data were collected because very little runoff was generated
by the small storms that occurred in the watershed since the station was installed.
SWPS-3 Station SWPS-3 is the upstream receiving stream station located near the upper
mining limit. SWPS-3 is located on Deadman Wash and provides pre-mining,
undisturbed data.
SWPS-4 Station SWPS-4 was located on Deadman Wash, downstream from SWPS-3.
SWPS-4 was the disturbed watershed paired with SWPS-3 during the
experimental period (1984-1987). The site was decommissioned in 1987 and
mined through in 1988.
SWPS-7 Station SWPS-7 was located on Deadman Wash, just above the outlet of the
SWPS-8 watershed. SWPS-7 was the undisturbed watershed paired with SWPS-8
during the experimental period (1984-1987). The site was decommissioned in
1987.
SWPS-8 Station SWPS-8 monitors a disturbed watershed on a tributary of Deadman Wash.
SWPS-8 is located approximately 1,000 feetupstream from Deadman Wash.
SWPS-9 Station SWPS-9 is a Deadman Wash downstream receiving station that is located
approximately 100 feet upstream from the confluence of Deadman Wash and Nine
Mile Draw.
SWPS-10 Station SWPS-10 is a disturbed watershed location on Nine Mile Draw. This
location is located approximately 300 feet upstream from the confluence of Nine
Mile Draw and Deadman Wash.
SWPS-13 Station SWPS-13 is upstream from the pit and represents the receiving stream.
SWPS-14 Station SWPS-14 is downstream of all mining disturbance in the Ten Mile Draw
drainage basin.
5.2.5 Data Reduction
During the first permit term, the discharge monitoring data were reduced using standard
U.S. Geological Survey (USGS) procedures for continuous sediment and water stage data. The
reduced data were then analyzed using either a covariance test or a modified Student's t - test in
order to determine whether degradation occurred in the receiving stream as a result of the
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Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
disturbed area runoff.
2.
3.
During the second and all subsequent permit terms, the data reduction procedure followed
Porterfleld (1972). This procedure is summarized as follows:
1. The stage recorder chart is adjusted for any pen, data, or time corrections that are
applicable.
Discrete sediment sample data are used to construct a continuous temporal
sediment concentration graph on the same scale as the flow record.
Water stage and sediment graphs are subdivided by mid-intervals into discrete
water discharge, sediment concentration, and sediment discharge values. In order
to avoid biasing the data in subsequent analyses, equal time intervals are used for
the disturbed stream and receiving stream subdivisions.
The subdivided water discharge and sediment discharge data are used to calculate
storm sediment yields in tons per acre and storm water yields in acre-feet per
square mile.
A log-log data plot of all monitoring stations is prepared with storm sediment
yield plotted against storm water yield.
5.
5.2.6 Data Analysis
Once data have been reduced they are analyzed to determine if degradation has occurred
(i.e., sediment yield has increased over background conditions). During the first permit term
(1984-1987), the discharge monitoring data were reduced using standard USGS procedures for
continuous sediment and water stage data. The allowable TSS change criteria initially were
based on a statistical comparison of storm sediment concentrations in the receiving stream before
and after addition of the disturbed area runoff. Sediment data were analyzed with either a
covariance test (for multiple pairs), or a modified Student's t - test (for a single pair of TSS data
points) in order to determine whether degradation of the receiving stream (Deadman Wash) by
the disturbed area runoff occurred. Since no degradation had been detected in over 65 storms,
ASC control techniques were determined to be successful.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
1 , ii
A simpler method for assessing differences in TSS concentrations between paired
watersheds was approved for the second and subsequent terms of the permit. First, instantaneous
TSS concentrations and flow rates are collected at adequate intervals to accurately calculate
storm water and sediment yield. An example of reduced storm yield data is presented in Table
5g.
Table 5g: Example Water and Sediment Yield Data (1984 -1998).
Station
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-3
Date
7/31/84
6/25/85
7/18/85
7/23/85
7/30/85
4/24/86
5/8/86
7/4/86
8/29/86
9/24/86
9/26/86
9/27/86
5/29/87
5/30/87
6/9/87
9/3/87
9/4/87
7/12/89
9/19/89
8/21/90
5/22/91
6/1/91
6/13/91
7/25/91
9/9/91
9/29/91
7/11/92
7/21/92
6/3/93
6/17/93
Stream Type
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Water Yield
(acre-ft/mi2)
1.477484022
0.005176922
0.031431064
0.11673182
0.080180455
0.002708907
0.009636635
0.010107986
0.003897468
0.001839712
0.002459572
0.001592364
0.02346527
0.002834567
0.025076508
0.007832187
0.021765622
0.00843516
0.010161131
0.001368857
0.011213602
0.519122156
0.03358617
0.12759526
0.034409669
0.13113313
0.333143
0.063889
0.094653
0.16531
Sediment Yield
(tons/acre)
0.050618459
0.0000418
0.00089235
0.005699971
0.001962336
0.0000293
0.0000606
0.0007701
0.00012434
0.0000272
0.0000167 .
0.000009
0.00057052
0.0000439
0.0005538
0.00028004
0.00035631
0.00030093
0.00017763
0.000008
0.00036676
0.012856543
0.00099266
0.00192681
0.001002066
0.004085589
0.004893302
0.001587215
0.00055171
0.00061545
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Development Document - Proposed Western Alkaline Coal Mining Subcateeoi
L
Station
SWPS-3
SWPS-3
SWPS-3
SWPS-3
SWPS-4
SWPS-4
SWPS-4
SWPS-4
SWPS-4
SWPS-4
SWPS-4
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-7
SWPS-8
JSWPS-8
JSWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-8
SWPS-9
Date
6/26/93
9/12/94
5/25/96
9/8/95
7/31/84
7/18/85
7/23/85
7/30/85
7/4/86
9/3/87
9/4/87
7/31/84
8/6/84
8/18/84
9/6/84
7/18/85
7/20/85
7/23/85
7/30/85
7/4/86
5/29/87
6/9/87
9/3/87
9/4/87
7/9/84
7/31/84
8/6/84
8/18/84
9/6/84
7/30/85
5/29/87
7/23/89
9/18/89
7/20/90
9/4/90
7/12/92
7/21/92
6/7/93
7/26/93
9/7/95
9/21/97
7/31/84
Stream Type
Receiving
Receiving
Receiving
Receiving
Disturbed
Disturbed
Disturbed
Disturbed ...
Disturbed
Disturbed
Disturbed
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Receiving
Water Yield
(acre-ft/mi2)
0.14757
0.005984
0.014834
0.090383
1.281434215
0.038092331
0.089620306
1.315367177
0.017723258
0.036651076
0.051385958
0.883773652
0.018663956
0.008212654
0.078186652
0.026335062
0.037043061
0.080330902
1.64197228
0.031810992
0.049678773
0.010749402
0.017177596
0.06342408
0.864063707
2.989430677
1.377395402
0.65060337
2.053912776
7.646761495
0.942419621
16.7603059
.953010004
0.756138294
24.80262338
.338507
0.386208
.28865
.903206
.5058
.292154
.968139808
Sediment Yield II
(tons/acre)
0.004199484
0.00011808
0.0000742
0.002519272
0.059088767
0.00066273
0.006017068
0.037101028
0.00096693
0.002640955
0.001527354
0.03245597
0.00091022
0.00029353
0.002446697
0.00052174
0.001852661
0.004302842
0.036970469
0.001072226
0.002706261
.00050693
.0008806 -
.001558256
.039664882
.346925851
.128622236
.029959021
.0679606
.747331783
.034361881
.85378317
.05122973
.017944103
729661636
0401 14953
03935179
008883994
129072306
220394066
048861472
066406744
Case Studies
5-21
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Station
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-9
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
Date
8/6/84
9/6/84
7/18/85
7/20/85
7/23/85
7/30/85
6/9/87
9/19/89
8/4/90
5/15/91
8/4/91
9/7/95
9/21/97
7/24/98
7/25/98
8/3/98
7/21/84
7/31/84
8/1/84
8/4/84
8/23/84
9/6/84
9/13/84
9/21/84
6/25/85
7/18/85
7/20/85
7/23/85
7/30/85
9/2/85
9/11/85
9/19/85
7/4/86
7/9/86
9/8/86
7/11/87
9/4/87
7/26/88
8/3/88
7/12/89
7/23/89
9/18/89
Stream Type
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Receiving
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Water Yield
(acre-ft/mi2)
0.030162507
0.340016234
0.037446771
0.393764689
0.145318019
2.115498217
0.046868004
0.60228965
0.377490999
0.524044071
0.137681387
1.280506
0.808959
0.233039
0.114991
0.070143
0.027840712
1.273303295
0.059938324
0.024953331
0.187992353
1.220188727
0.29014207
0.086033362
0.225655459
0.088624058
1.274837051
0.490645525
1.892771051
0.301326036
0.224095213
0.285482526
0.065318389
0.03566578
0.040836576
0.045726581
1.077011708
0.345285
0.881732
10.2879986
9.266459047
0.204264997
Sediment Yield
(tons/acre)
0.001983688
0.023758994
0.00087062
0.024798275
0.005443206
0.129639835
0.003246825
0.013080951
0.009658689
0.00476637
0.003731229
0.037841673
0.036334021
0.006275786
0.003876858
0.003449813
0.00060744
0.063190439
0.001226025
0.00072447
0.004881808
0.024843723
0.01063298 -
0.00068546
0.004346816
0.003332559
0.057595307
0.016545764
0.07519991
0.014233035
0.004608739
0.00433567
0.003137509
0.00096967
0.001148005
0.00097525
0.01375377
0.023645
0.034852
0.4594194
0.493653359
0.007283703
5-22
Case Studies
-------
Development Document - Proposed Western Alkaline Coal Mi
nins
Station
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-10
SWPS-13
SWPS-14
SWPS-14
Date
9/19/89
9/20/89
7/20/90
7/24/90
8/4/90
8/30/90
6/1/91
6/13/91
8/27/91
9/9/91
9/29/91
6/3/93
6/17/93
7/26/93
8/11/93
9/17/93
9/18/93
9/8/95
9/21/97
9/21/97
9/21/97
7/9Q/Q8
Stream Type
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Disturbed
Receiving
Disturbed
T~)i Qf nrHfv^
Water Yield
(acre-ft/mi2)
1.70304627
0.350679062
0.005629069
6.277730829
0.207790781
1.216872212
1.261933901
0.289479827
0.068529
0.040127
0.019763991
0.38052
0.820869
0.576255
0.077249
0.030802
1.749732
0.155225
2.60624
9.156198
0.039105
0 D09404
Sediment Yield
(tons/acre)
0.026197923
0.004809361
0.00015047
0.26287646
0.010900476
0.064923592
0.079357249
0.013982257
0.00109785
0.00635304
0.00064645
0.006587097
0.007857705
0.019192863
0.002496633
0.00046812
0.02525054
0.004313379
0.107340165
D.139136745
.001971105
AAA^OO/CQ
Next, the 95% prediction bands confining the regression equation y = 0.0339(x)
1.0925
are
calculated using Equation 5a developed for predicting any value of "y" for a given "x"
(Kleinbaum, 1978). Unit water and sediment yield are plotted with the 95% prediction intervals
in Figure 5c and a graphical comparison is made of the individual storm sediment yield relative
to the general trend. Any points (storms) which fall inside the 95% prediction interval show that
no significant variation from background sediment yield has occurred. If the disturbed
monitoring station points (storms) plot above the predicted interval, degradation has technically
occurred and mitigation measures are immediately taken. No unit sediment yields, of storms less
than a 10-year, 24-hour event, plotted outside of the confidence bands between 1984 and 1998.
Case Studies
5-23
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Equation 5a
y0 = Y + BI(XO - x) ± t(n.2) 1_aa> * sy/x *
(1
, 1 ,
n
(X0
(n -
-X)2
1) * sx
Where:
Y = Mean of Y values
=; = Mean of X values
B, = Coefficient of Regression Equation
X0 = Value in Question
y0 = Value in Question
*
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
2>
o
•25
in
o
0)
CD
^
0)
Rgure 5c: Sedinrent Yield vs. V\feter Yield
10
1 -:
0.1 -:
0.01 -:
0.001 -:
0.0001 -: /
0.00001 -:
0.000001
y=0.0339x1-0925
R=0.9321
P'*
i Dstubed 1984-1998
a Ffeceiving 1934-1998
---x--- UJ3per95%Band
---+-- -Lower 95% Band
Ftegression Line
0.001
0.01 0.1 1
Water Yield (aneflfeqjri.)
10
100
Case Studies
5-25
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
To confirm that the use of ASCs are effective, Bridger also conducts annual surveys of
the receiving streams. For example, Bridger Coal Company has conducted an annual survey of
Nine and One-Half Mile Draw since 1987. The surveys include up to nine cross sections used to
model Nine and One-Half Mile Draw. Two cross sections are located upstream from the final
highwall, three are located in the reclaimed reach, and four are located downstream from the
boxcut disturbance limit. Areas of head cutting, aggradation, or degradation are noted and
reported each year. Based on data available (up to 1992), no aggradation or degradation has been
detected downstream of the disturbance in Nine and One-Half Mile Draw.
5.2.7 Summary
ASC technology is the primary means of sediment control at the Jim Bridger Mine.
Ongoing surface water monitoring is used to detect the impact of mine disturbance treated with
ASC techniques on receiving stream water quality. Analysis of monitoring results to date (1984-
1998, Table 5g) has shown that, for storm events less than 10-year, 24-hour, background
sediment levels have not been exceeded in disturbed watersheds. Analysis also has shown that
sediment in disturbed watersheds correspond to sediment in receiving watersheds relative to
sediment storage and release. These ASC design and monitoring methods have proven
successful over a lengthy period of experimentation, evaluation, and application.
5-26
Case Studies
-------
'. Development Document - Proposed Western Alkaline Coal Mining Subcatezory
5.3 Case Study 3 (Water Engineering & Technology, Inc., 1990)
Case Study 3 summarizes a study performed for the Office of Surface Mining
Reclamation and Enforcement during 1987-1989. This extensive project was jointly
commissioned by the National Coal Association, the Office of Surface Mining Reclamation and
Enforcement, BHP-Utah International Inc., Peabody Coal Company, and the Pittsburgh and
Midway Coal Mining Company and was prepared by Water Engineering & Technology, Inc.
Details of the project are provided in the "Determination of Background Sediment Yield and
Development of a Methodology for Assessing Alternative Sediment Control Technology at
Surface Mines in the Semiarid West" (WET, Inc., 1990).
The study had four major objectives:
• Assess average annual background sediment yield at three mine sites based on
surveying and computation of sediment accumulation in ponds;
• Evaluate available computer models for prediction of watershed runoff and
sediment yield, and selection of the model that best represents these processes at
semiarid mine sites;
• Evaluate runoff and erosion response to rainfall using rainfall simulation testing
on test plots (12 feet wide by 35 feet long). Use resulting data and information to
calibrate and validate the computer model selected; and
• Apply the model to evaluate alternative sediment control practices and the ability
of such practices to maintain erosion from reclaimed lands at or below
comparable background erosion levels.
The study targeted sedimentation and erosion conditions in semiarid coal regions using
data and information collected at the at Navajo Mine near Farmington, New Mexico (BHP-Utah
International, Inc.), McKinley Mine near Gallup, New Mexico (Pittsburgh & Midway Coal
Company), and the Black Mesa Mine near Kayenta, Arizona (Peabody Coal Company). All three
mines are located in a semiarid environment where sediment yield is large and variable. Erosion
generally results from the occurrence of short duration, high intensity rainfalls.
Case Studies 5-27
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
5.3.1 Background Sediment Yield
Surveys were conducted in ponds located near the McKinley and Navajo Mines to
determine average sediment yields from undisturbed, semiarid watershed basins. No suitable
ponds were identified at the Black Mesa Mine.
Eight ponds were surveyed near the McKinley Mine. Measured sediment yields
(sedimentation rate, tons/acre/year) ranged from 0.11 to 3.2 tons/acre/year. The average
sediment yield was 1.16 tons/acre/year with a standard deviation of 1.13 tons/acre/year. The
lowest value of sediment yield was measured in a pond corresponding to basins with low relief
and low hillslope gradients (MCM-3). The highest values of sediment yield were measured in
ponds corresponding to basins with incised channels (MCM-1, 2, and 8). Ten ponds were
surveyed near the Navajo Mine. Measured sediment yields for the Navajo Mine ponds ranged
from 1.56 to 16.00 tons/acre/year. The average sediment yield was 4.82 tons/acre/year with a
standard deviation of 4.54 tons/acre/year.
Sediment volume, sediment density, and sedimentation rate results from basins located
near the McKinley and Navajo Mines are presented in Table 5h. The high variability in sediment
yields is thought to be attributed in part to the age of the ponds (from 8 to 38 years), size of the
basin drainage areas (averages are 0.17 and 0.64 square miles for Navajo and McKinley Mines,
respectively), and types of soil (clay, sandy loam, loam, sandy clay loam, and clay loam).
5-28
Case Studies
-------
Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
Table Sh: Measured Sediment Yields at Navajo and McKinley Coal Mines
Pond
NM-2
NM-3
NM-4
NM-5
NM-6
NM-7
NM-8
NM-9
NM-10
NM-11
MCM-1
MCM-2
MCM-3
MCM-4
MCM-,6
MCM-7
MCM-8
MCM-9
Sediment
Volume
(ft3)
152,440
115,060
39,110
25,140
5,180
55,440
21,860
25,390
221,780
113,710
175,690
220,100
71,000
137,830
120,310
105,770
642,370
154,350
Drainage
Area
(acres)
109
183
42.2
57.6
19.2
71.6
5.1
64.0
320
192
89.6
110.2
570
211
580.4
173
224
509
Age
(years)
8
8
8
8
8
8
8
8
8
15
33
34
33
33
38
37
36
31
Sediment
Density
(Ibs/ft3)
107
100
77.8
82.6
92.7
60.6
60.6
87.1
89.1
82.3
68.9
72.7
58.5
68.5
81.0
71.5
79.4
69.4
Sedimentation
Rate
(tons/acre/yr)
9.36
3.93
4.50
2.25
1.56
2.93
16.00
2.16
3.86
1.62
2.05
2.13
0.11
0.68
0.23
0.59
3.16
0.34
NM = Navajo Mine
MCM = McKinley Mine
Case Studies
5-29
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
In general, sediment yields measured from the Navajo Mine basins were greater than
those from the McKinley Mine basins. This observation has been attributed to the following
factors:
• average drainage area for the Navajo Mine basins (0.17 square miles) is less than
the average drainage area for basins at the McKinley Mine (0.64 square miles);
• drainage density is greater at the Navajo Mine basins. (15.2 miles/square miles)
than at the McKinley Mine basins (4.2 miles/square miles);
• the vegetation density is greater near the McKinley Mine basins (41 percent) than
for basins near the Navajo Mine (15 percent); and
• ., the Navajo Mine basins have badland soil associations and none of the McKinley
mine basins have badland soil associations.
The usefulness of this information for evaluation of background, sediment yield is limited
by several factors. First, the age of the the ponds was often uncertain and some may not have
been in existence long enough to have received runoff and sediment resulting from large storm
events that control watershed response in a semiarid environment. Second, reliable
measurements of sediment yield can only be obtained if the ponds have not been breached or
overtopped, and this information was not known. Third, ponds should be located in basins
having geologic properties and morphometric (drainage area and density) properties similar to
those of the mine watersheds. Some of the ponds near the McKinley mine did not meet this later
condition and exhibited low rates of sediment yield possibly due to the presence of geologic
controls in channels and watersheds (i.e., exposed bedrock). Finally, sediment yield in the
semiarid west is largely governed by the occurrence of localized, relatively large storm events.
Without accurate data describing the rainfall conditions in the watershed, it is difficult to
compute a meaningful average annual sediment yield. It is difficult to determine if the sediment
yield is the result of a single, rare storm event (i.e., 50-year storm) or the result of a sequence of
smaller events. Lacking accurate rainfall data, pond sediment volumes could not be used to
directly calibrate a computer model.
5-30
Case Studies
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Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
5.3.2 Evaluation of Watershed Computer Models
The second objective of the study was to assess available watershed hydrologic and
sediment transport models to determine the model most appropriate for use in evaluation of
alternative sediment control practices. Detailed evaluations were made of five models (Water
Engineering & Technology, 1990):
ANSWERS - Areal Nonpoint Source Watershed Environmental Response
Simulation
KINEROS - Kinematic Erosion Model
MULTSED - Watershed and Sediment Runoff Simulation Model for Multiple
Watersheds
PRMS - Precipitation-Runoff Modeling System
SEDIMOTII/SEDCAD version - Hydrology and Sedimentology Watershed
Model E
Each model was evaluated with respect to:
• watershed representation;
• rainfall components;
• infiltration, interception and surface detention components;
• runoff components;
• sedimentation components;
• ease of file generation;
• performance with test data; and
• sensitivity analysis of the various inputs and parameters.
Rather than developing an artificial data set to test the models, a data set obtained from
the USDA-ARS Sedimentation Laboratory, Oxford Mississippi for a 4.7 acre, severely eroding
soybean field in northwest Mississippi was used. These data include nine events that occurred
during the 1985-1986 growing season and represent a wide range of vegetation cover. Two of the
nine events were relatively extreme (both of approximate 10-year return periods, one having a
duration of two hours and the other having a duration of four hours). Accurate measurements of
rainfall, runoff and sediment yield were available for each event at this site, and the topography
of the field was surveyed in great detail. Although this data set does not represent coal mines in a
semiarid environment, the processes of infiltration, runoff generation, soil detachment, sediment
transport and deposition can be considered universal.
Case Studies
5-31
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Results of computer model tests are presented in Table 5i. Five models were ranked from
one (most accurate) to five (least accurate) for seventeen categories. Twelve categories deal with
physical processes. The other categories are (1) watershed representation, (2) generalization of
watershed reproduction, (3) ease in subdividing watersheds and generating watershed data, (4)
ease in generating other data files, and (5) performance of the model with test data.
Table Si: Ranking of Five Computer Models
Category
Rainfall
Interception
Infiltration
Hillslope
Channel
Runoff
Hillslope
Channel
Detachment
Hillslope
Channel
Transport
Hillslope
Channel
Deposition
Hillslope
Channel
Watershed Representation
Generality
Generation
Performance with Test Data
Data File Generation
Areas of Concern
Sum of Ranks
Number of First Ranks
ANSWERS
P 2
P 3
E 4
N 4
P 2
P 2.5
P? 2.5
N 3
P? 1.5
P? 1.5
P? 1
P? 1.5
1.5
5
3
4
2
44
8
KINEROS
P 2
P 3
P 2
P 2
P 1
P 2.5
P? 2.5
P? 2
P? 3
P? 3
P? 2
P? 3
1.5
3
1.5
2
3
39
7
MULTSED
P 2
P 1
P 2
P 1
P 4
P 2.5
P? 2.5
P? 1
P? 1.5
P? 1.5
N 4
P? 1.5
4
3
1.5
3
1
37
12
PRMS
P 4
P 3
P 2
N 4
P 3
P 2.5
P? 2.5
N 4.5 .
P? 4
P? 4.5
N 4
N 5
4
3
(1 to 5)
5
5
(60 to 65)
3
SEDIMOT
II
S 5
S 5
S 5
N 4
S 5
P-S 5
S 5
N 4.5
S 5
E 4.5
N 4
E 5
4
1
4
1
4
70
2
E = Empirical Relationship; N = Not Simulated; P = Process Based; P? = Process Assumption
1 = Highest Rank; 5 = Lowest Rank
5-32
Case Studies
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
As a result of these analyses, the MULTSED model achieved the most number of first
place scores. Therefore, MULTSED was selected for use in subsequent phases of this project.
5.3.3 Rainfall Simulation Data Collection
Rainfall simulation testing was conducted at the Navajo Mine during 1987 and 1988 and
at the McKinley Mine during 1988 to measure and collect data regarding the following
parameters:
rainfall
runoff
sediment yield
soil properties
vegetation and cover densities
By testing paired plots (one plot to be used for model calibration and one to be used for
model verification) and collecting data from two simulated rainstorms, four sets of data were
obtained from each test site. Test sites encompassed a range of slopes, ages of reclamation and
reclamation practices and included five test sites in undisturbed areas at each mine. The rainfall
simulation testing program provided 76 data sets describing the rainfall-runoff-erosion process at
the Navajo Mine (19 sites x 2 plots x 2 test runs) and 80 data sets at the McKinley Mine (20 sites
x 2 plots x 2 test runs).
In addition, data were available for the Black Mesa Mine from 24 test plots (10-feet wide
by 35-feet long) representing a range of slopes, surface treatments and watershed size (from 3 to
41 acres). Runoff and sediment yield generated by natural rainfall for Navajo Mine and
McKinley Mine test plots and Black Mesa Mine watersheds were available for the period of 1983
to 1987. Tables 5j, 5k, and 51 contain a summary of the runoff and sediment yield information
obtained from the Navajo, McKinley, and Black Mesa Mines, respectively.
Case Studies
5-33
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Table 5j: Rainfall, Runoff and Sediment Yield Data for Navajo Mine
Plot
1
2
3
4
5
6
Storm
Event
Run
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
3
3
1
1
2
2
1
1
2
2
3
3
4
4
SubPlot
ID
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Total Rainfall
(in)
2.5
2.2
2.6
2.6
2.0
2.0
2.7
2.6
2.0
2.7
2.1
2.4
2.3
1.8
2.2
1.0
2.1
1.4
2.0
2.3
2.7
2.2
2.9
2.7
2.8
2.6
NDC
2-4.
NDC
1.4
Total Runoff
(in)
1.42
0.72
2.02
2.08
0.91
1.23
1.66
1.76
0.75
0.85
1.31
1.31
1.97
1.72
1.36
0.87
1.88
1.06
0.28
0.71
0.90
0.98
0.40
0.33
1.10
1.18
NDC
1.32
NDC
1.05
Total Sediment
Yield
dbs)
27.0
6.7
36.8
33.0
16.3
18.0
41.2
34.9
10.1
13.0
32.4
30.0
38.2
28.3
17.6
9.0
23.6
10.6
0.8
1.4
6.1
5.4
0.0
0.6
1.8
5.0
-
2.2
-
1.5
Average Sediment
Concentration
(ppm)
8,690
4,240
8,320
7,260
8,180
6,690
11,400
9,070
6,210
6,970
11,300
10,500
8,890
7,530
5,920
4,720
5,740
4,600
1,310
922
3,110
2,530
35
849
727
1,920
-
759
-
636
5-34
Case Studies
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Development Document - Proposed Western Alkaline Coal Mining Subcatesory
Plot
7
8
9
10
11
12
13
14
14
Storm
Event
Run
1
1
2
2
1
1
2
2
3
3
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
SubPlot
ID
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Total Rainfall
(in)
2.3
2.2
2.6
2.3
3.1
2.0
2.7
2.7
2.2
1.8
2.3
2.7
2.4
2.2
2.6
2.7
2.1
2.3
2.3
2.2
2.4
2.0
2.2
2.2
2.5
2.3
2.4
2.2
2.7
2.4
2.3
2.4
2.2
Total Runoff
(in)
0.50
0.81
0.68
1.14
0.27
0.32
0.14
0.14
0.42
0.42
1.32
0.53
2.26
1.89
1.24
1.20
1.62
1.50
1.12
1.02
1.68
1.29
1.32
1.26
2.07
1.94
0.00
0.00
0.41
0.44
0.36
0.17
1.66
Total Sediment
Yield
dbs)
0.3
0.4
0.6
0.6
0.3
0.2
0.1
0.1
0.4
0.4
209.0
244.8
341.1
240.8
4.8
4.0
7.5
7.6
6.9
11.5
22.5
19.2
209.2
176.2
314.7
306.1
0.0
0.0
0.8
1.0
1.2
0.4
11.8
Average Sediment
Concentration
(ppm)
283
238
281
224
501
359
434
416
471
404
72,500
73,200
68,900
58,300
1,790
1,550
2,130
2,320
2,800
5,160
6,150
6,800
72,200
64,100
69,600
72,200
0
0
866
1,050
1,490
996
3,240
Case Studies
5-35
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Plot
15
16
17
18
19
Storm
Event
Run
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
SubPlot
ID
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Total Rainfall
(in)
2.6
2.6
2.6
2.5
2.6
2.5
2.6
2.9
2.9
2.4
2.4
2.8
2.8
2.3
2.0
2.5
2.5
2.6
2.3
3.1
2.5
Total Runoff
(in)
1.58
0.00
0.20
0.70
1.50
0.55
0.47
2.51
2.56
2.03
1.97
2.50
2.69
0.63
0.28
1.24
1.30
2.33
1.98
2.92
1.90
Total Sediment
Yield
(Ibs)
9.6
0.0
0.4
1.4
7.2
1.6
2.2
5.5
6.1
107.6
98.9
106.3
136.4
0.8
0.2
2.3
1.4
38.3
35.3
46.5
36.0
Average Sediment
Concentration
(ppm)
2,790
0
809
945
2,200
1,380
2,100
1,010
1,080
24,200
23,000
19,400
23,200
569
396
849
496
7,530
8,150
7,280
209.0
5-36
Case Studies
-------
Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
Table 5k: Rainfall, Runoff and Sediment Yield Data for McKinley Mine
Plot
1
2
3
4
5
6
7
8
8
Run
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
SubPlot
ID
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Total
Rainfall
(in)
1.9
2.8
3.0
2.4
1.9
1.8
2.7
2.6
2.8
2.1
3.0
1.8
2.5
3.4
2.6
3.0
3.6
3.2
3.1
2.9
2.5
3.0
3.1
3.0
3.1
2.9
2.4
3.3
2.7
2.8
Total
Runoff
(in)
0.09
0.98
0.81
1.05
0.09
0.06
0.62
0.41
0.74
0.61
1.43
0.77
1.02
1.32
1.63
1.68
1.40
0.87
1.74
1.09
0.82
1.46
1.45
1.71
0.53
0.012
0.98
1.28
1.02
0.94
Total
Sediment
Yield
Obs)
0.6
6.2
6.3
6.0
0.1
0.1
2.4
3.7
4.1
18.8
8.2
4.6
6.2
7.3
6.7
5.9
15.1
13.8
14.6
12.2
4.8
8.6
7.0
10.5
0.5
0.04
0.5
2.8
3.8
2.8
Average
Sediment
Concentration
(ppm)
3,150
2,880 II
3,550
2,630
689
735
1,400
3,350
2,520
14,000
2,610
2,750
2,800
2,530
- 1,880
1,590
4,940
7,240
3,830
5,100
2,680 1
2,690 I
2,210 I
2,820
322
1,530
184
923
1,710
1,340
Case Studies
5-37
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Plot
9
10
11
12
13
13
14
15
16
Run
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
SubPlot
n>
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Total
Rainfall
(in)
3.1
2.9
2.3
3.1
2.8
2.9
3.2
2.9
2.6
2.2
3.1
3.4
3.2
2.5
2.9
3.0
1.9
2.4
2.3
3.1
2.5
2.6
2.6
2.3
2.5
2.7
2.4
2.5
2.3
3.1
2.6
2.4
Total
Runoff
(in)
1.81
1.86
0.46
0.81
1.13
1.02
0.42
0.17
1.04
0.45
0.89
1.44
2.05
1.66
1.67
1.88
1.28
2.21
0.74
0.98
1.27
1.41
1.48
1.22
1.47
1.75
1.65
1.46
2.00
2.19
2.38
1.98
Total
Sediment
Yield
0bs)
7.3
7.8
1.9
8.2
8.4
12.6
5.6
0.6
9.3
3.3
19.5
39.1
• 44.2
31.2
21.5
17.1
10.9
14.1
12.0
32.3
19.4
31.5
7.0
5.4
6.5
8.6
7.1
8.3
9.3
10.9
153.7
115.7
Average
Sediment
Concentration
(ppm)
1,840
1,910
1,910
4,640
3,420
5,650
6,180
1,650
4,100
3.340
10,010
12,470
9,850
8.580
5,900
4,170
- 3,920
2,920
7,430
15,050
6,980
10,230
2,150
2,000
2,040
2,260
1,960
2,610
2,120
2,280
29,500
26,780
5-38
Case Studies
-------
Development Document - Proposed Western Alkaline Coal Mining Subcatezorv
Plot
17
18
19
20
Run
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
SubPIot
ID
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Total
Rainfall
(in)
2.4
2.2
3.0
2.8
3.0
3.4
2.3
3.1
3.1
2.5
2.7
2.7
2.7
3.3
2.4
2.6
2.7
2.8
Total
Runoff
(in)
1.89
1.83
0.35
0.55
0.90
1.09
0.80
1.10
1.78
1.42
0.99
0.57
1.90
1.90
1.54
1.62
2.19
2.27
Total
Sediment
Yield
dbs)
100.5
81.3
4.8
9.6
6.0
13.3
11.7
40.5
53.6
42.1
3.0
2.0
4.9
4.8
86.5
95.8
93.4
1000
Average
Sediment
Concentration
(ppm)
24,290
20,350
6,330
7,960
3,070
5,550
6,730
16,890
13,760
13,550
1,320
1,420
1,130
1,050
25,710
27,070
- 19,510
20 160
Case Studies
5-39
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Table 51: Rainfall, Runoff and Sediment Yield Data for Black Mesa and Kayenta Mines
Watershed
N2 Small
N2 Large
J27
Run Date
7-21-86
8-31-86
9-23-86
7-30-87
8-31-86
9-23-86
7-30-87
7-21-86
8-31-86
7-30-87
7-21-86
8-31-86
9-23-86
7-30-87
8-31-86
9-23-86
8-31-86
9-23-86
7-30-87
8-31-85
9-11-85
7-20-86
9-23-86
8-31-85
9-11-85
7-20-86
9-23-86
8-31-85
9-11-85
7-20-86
Plot ro
221
222
223
224
225
226
271
272
273
Total Rainfall
(in)
0.9
0.5
0.9
0.6
0.5
0.9
0.6
0.9
0.5
0.6
0.9
0.5
0.9
0.6
0.5
0.9
0.5
0.9
0.6
0.5
0.3
0.5
1
0.5
0.3
0.4
1
0.5
0.3
0.5
Total Runoff
(in)
0.012
0.162
0.057
0.195
0.256
0.103
0.147
0.005
0.116
0.067
0.005
0.094
0.024
0.068
0.161
0.138
0.184
0.149
0.219
0.004
0.010
0.006
0.010
0.006
0.010
0.007
0.010
0.027
0.007
0.005
Total Sediment
Yield
(Ibs)
0.190
4.391
0.208
1.709
8.077
1.172
4.049
0.012
1.849
0.282
0.010
0.796
0.042
0.275
3.049
0.250
4.538
0.377
1.418
0.004
0.002
0.003
0.003
0.015
0.008
0.011
0.067
0.098
0.010
0.009
Average Sediment
Concentration
(ppm)
8,710
14,900
1,990
4,810
17,300
6,260
15,100
1,360
8,720
2,330
1,120
4,630
960
2,230
10,400
991
13,500
1,390
3,560
500
107
288
156
1,440
442
893
3,720
1,970
876
886
5-40
Case Studies
-------
Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
Watershed
J27 (cont.)
J3
J3 (cont.)
Run Date
9-23-86
8-31-85
9-11-85
9-23-86
8-31-85
8-31-85
9-11-85
9-23-86
7-29-85
9-11-85
9-18-85
8-29-86
9-08-86
8-08-87
7-29-85
9-11-85
9-18-85
8-29-86
9-08-86
8-08-87
7-29-85
9-11-85
9-18-85
8-29-86
9-08-86
8-08-87
7-29-85
9-11-85
9-18-85
8-29-86
9-08-86
8-08-87
7-29-85
Plot ID
274
275
276
303
304
305
306
307
Total Rainfall
(in)
1
0.5
0.3
1
0.5
0.5
0.3
1
1
0.6
0.5
0.2
0.3
0.9
1
0.6
0.5
0.2
0.3
0.9
1
0.6
0.5
0.2
0.3
0.9
1
0.6
0.5
0.2
0.3
0.9
1
Total Runoff
(in)
0.078
0.008
0.005
0.049
0.037
0.017
0.003
0.047
0.307
0.100
0.026
0.015
0.017
0.030 '
0.436
0.118
0.085
0.015
0.033
0.102
0.436
0.176
0.133
0.048
0.089
0.176
0.257
0.024
0.023
0.026
0.028
0.101
0.163
Total Sediment
Yield
(Ibs)
0.167
0.013
0.002
0.089
0.087
0.026
0.000
0.095
7.802
0.455
0.132
0.155
0.198
0.390
10.538
0.512
0.143
0.153
0.315
1.160
16.936
1.529
0.400
0.847
1.508
4.009
3.354
0.098
0.067
0.318
0.144
0.861
3.755
Average Sediment
Concentration
(ppm)
1,180
984
242
997
1,310
848
0
1,110
13,900
2,490
2,770
5,850
6,270
7,130
13,300
2,390
927
5,650
5,270
6,230
21,300
4,760
1,650
9,730
9,280
12,500
7,170
2,270
1,620
6,700 1
2,810
4,690 I
12,700 I
Case Studies
5-41
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Watershed
N6
Run Date
9-11-85
9-18-85
8-29-86
7-29-85
9-11-85
9-18-85
8-08-87
9-18-85
9-23-86
9-18-85
9-23-86
9-18-85
7-21-86
9-08-86
9-23-86
9-18-85
7-21-86
9-08-86
9-23-86
9-18-85
7-20-86
7-21-86
9-23-86
9-18-85
7-20-86
7-21-86
9-23-86
Plot ID
308
261
262
263
264
265
266
Total Rainfall
(in)
0.6
0.5
0.2
1
0.6
0.5
0.9
0.4
0.8
0.4
0.8
0.4
0.6
0.9
0.8
0.4
0.6
0.9
0.8
0.4
0.5
0.6
0.8
0.4
0.5
0.6
2.5
Total Runoff
(in)
0.084
0.024
0.006
0.180
0.080
0.024
0.028
0.023
0.074
0.018
0.072
0.003
0.012
0.191
0.090
0.017
0.017
0.106
0.115
0.006
0.005
0.028
0.045
0.010
0.005
0.018
0.039
Total Sediment
Yield
dbs)
0.397
0.067
0.019
4.953
0.879
0.163
1.097
0.407
0.445
0.060
0.330
0.006
0.037
1.200
0.144
0.034
0.060
1.219
0.750
0.012
0.032
0.218
0.132
0.018
0.019
0.135
0.103
Average Sediment
Concentration
(ppm)
2,600
1,530
1,900
15,100
6,020
3,760
21,300
9,510
3,290
1,820
2,540
1,190
1,670
3,450
884
1,090
1,900
6,310
3,570
1,130
3,880
4,200
1,610
993
1,980
4,110
1.440
5-42
Case Studies
-------
'. Development Document - Proposed Western Alkaline Coal Mining Subcategory
5.3.4 Calibration and Validation of the MULTSED Model
The first step in the application of MULTSED for prediction ofrunoff and sediment yield
involved calibration and validation of the model using the data collected from the Navajo,
McKinley, and Black Mesa/Kayenta mines. One-half of the simulated rainfall test plot data were
used for calibration and determination of appropriate infiltration and soil detachment
coefficients. Following calibration, the MULTSED model was run using the calibrated
infiltration and detachment coefficients to predict sediment yield and mean sediment
concentration. Finally, total runoff, sediment yield, and mean sediment concentration predicted
by MULTSED were compared to the remaining half of the simulated rainfall test plot data and to
the available Black Mesa/Kayenta Mine data. Model verification determined that runoff amounts
were predicted with the greatest accuracy, followed by mean concentration, and sediment yields.
Model results also showed a tendency for the model to over predict sediment and runoff
rates for low flow conditions should not be of major concern because long-term erosion rates
generally are dominated by extreme conditions when large magnitude runoff volumes occur.
However, when predicting the runoff and sediment responses of various erosion control
alternatives, the model should not be used for small storms that produce small amounts of runoff
(< 0.5 inches).
5.3.5 Evaluation of Alternative Sediment Control Techniques
Successful calibration and validation of the MULTSED model provided a means to
evaluate the effectiveness of alternative sediment control techniques relative to background
conditions. To make these comparisons, a procedure was developed that uses rainfall depth-
duration information available from National Oceanic and Atmospheric Administration (NOAA)
Atlases at each mine site. Rainfall data describing storm events with recurrence intervals of 2, 5,
10, 25, 50, and 100 years were used to develop hypothetical storm distributions. MULTSED was
then used to determine the runoff and sediment generated from a hill slope for this range of storm
Case Studies 5.43
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
events.
Comparison were made between background sediment yield and predicted sediment
yields associated with alternative sediment control techniques. Average annual sediment yield
was computed using a probability weighting procedure that uses an incremental probability of
occurrence of the aforementioned sequence of storms. Since the average value computed using
this procedure is based on a broad range of storm events, it,is expected to represent a reasonable
long-term average. It should be noted that, depending on the sequence of storm events that
actually occur, sediment yield within any given year could significantly deviate from this average
value. For purposes of comparison, however, this calculation procedure provides a reasonable
value for sediment yield.
Modeling was performed to evaluate sediment yield response to variations in slope
length, slope gradient, cover density, and the presence or absence of furrows (depression storage)
on the reclaimed surface. The results agreed with expectations: sediment yield increases with
increasing plot slope gradient and slope length, decreases with increasing vegetative cover, and
decreases with increased depression storage. Model prediction results for the sediment yield
response to ASCs at the Navajo Mine, McKinley Mine, and Black Mesa/Kayenta Mine are
presented in Figures 5d through 5q.
5-44
Case Studies
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Development Document - Proposed Western Alkaline Coal Mining Subcatesory
Figure 5d: Navajo Mine Sediment Yield vs. Plot
Slope
0.16
o
-5
<2 0.12 -
s
•o 0.1 •
!s
^ 0.08 -
c
0>
.§ 0.06 ^
•o
0)
tn
— 0.04 -
(0
3
10 15 20
Plot Slope (Percent)
30
-Unmined Sandy Loam; 5% Cover
Reclaimed Sandy Loam; 10% Cover;0.1 inch Furrows
Reclaimed Sandy Loam; 5% Cover; No Furrow
-•Unmined Sandy Loam; 10% Cover
-Unmined Sandy Loam;15% Cover
Figure 5e: Navajo Mine Sediment Yield vs. Percent
Ground Cover
o
I
o
tn
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
20
40 60 80
Percent Ground Cover(%)
100
120
— Reclaimed Sandy Loam —at—Unmined Sandy Loam
Case Studies
5-45
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
,,»:
0 35 -
0.3 -
•a
~ 0.25 -
§"g 0.2 -
_ u
•D .«
$ 1 0.15 -
•s S
3 —
C 0.1 -
0 05 -
0 -
C
=igure 5f: Navajo M ine Sediment Yield vs. Slope
' Length
1 1 • •• . . •. • . • Hi ',' : i . • '
...B
.-a-'
ff--r
..•-'**"
.-*"""
.st~'
~* — ' '
yf~ -^~~*^~^
^ x
^^^ « X *'
X:::;::;.:..A * *
) 50 100 150 200 250 300 350
Slope Length (ft)
— • — Unmined Sandy Loam: 10% Canopy: n=0.03
...B... Reclaimed Sandy Loam; 10% Canopy; n=0.03
...x--- Reclaimed Sandy Loam; 10% Canopy; Furrow (0.1); n=0.05
Annual Sediment Yield (tons/acre/yr)
Figure 5g: NavajoMine Sediment Yield vs.
0.1 i
0.09 -
0.08 -
0.07 •
0.06 -
0.05 :
0.04 •
0.03 i
0.02 -
0.01 •:
0 -
C
Depression Storage
~-v
'"•*._
\
"'"•• ^ ^X. * *""X.N |
Jt K x » x"'"''"* x """ -^N! :
-*NS^
) 0.1 0.2 0.3 0.4 0.5 0.6
Depression Storage (in)
-^ — Unmined Sandy Loam; n=0.03 — x — Unmined Sandy Loam; n=0.05
5-46
Case Studies
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Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
Figure 5h: McKinley Mine Sediment Yield vs. Plot
Slope
0.3
*! 0.25
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
FigureSj: M cKinley M ine Sediment Yield vs. Slope
Length
0.9
£, 0.8 -
2
I °'7-
8 0.6 -
"3 O.S -
?
§*" 0.4 -
T3 0.3 -
§ 0.2 -
SO
100 150 200
Slope Length (ft)
250
300
350
• Unmined Loam; 10% Cover ---ss— Reclaimed Loam; 10% Cover
-A- - - Reclaimed Loam; 10% Cover; 0.1 Furrow s x Reclaimed Loam; 10% Cover; 0,3 Furrow s
Figure 5k: McKinley Mine Sediment Yield vs. Percent
Gound Cover
0.16
40 60 80
Percentage Ground Cover
100
-- Reclaimed Loam; No Cover •
-Unmined Loam; No Cover
120
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Development Document - Proposed Western Alkaline Coal Mining Subcatesory
03-i
"3 0.25 -
0
0 0.2 -
•a
a>
>• 0.15 -
1 }
£
•a 0.1 -
CO
T5
C 0 05 -
c
0 -
0
Figure 51: Me Kin ley Mine Sed im ent Yield vs.
Depression Storage
'" *
* ~* -,.
»--..,
~--,^
--B. ~*~--~,
-•%&•. . "--^,
* "-35- . " '^
v, -Vi •.j- ^ «^ '"~*~~-*^_. - • _
'" ' % '"• ' " ..,. t,. ... , , •*•' ' ^
.x. _..._....x
0.1 0.2 0.3 0.4 0.5 0.
Depression Storage (in)
A Unmined Loam; 10% Cover; n = 0.035 - ~x- Unmined Loam; 10% Cover; n = 0.05
6
1
o
'
03
Figure 5m: Black Mesa/Kayenta Mines Sedim ent Yield
vs. Plot Slope
0.7
0.3 -
$ 0.2 -
15 20 25
PlotSlope (percent)
-Unmined Loam ; 10% Cover —a---Reclaim ed Loam ; 1 0% Cover
-Reclaimed Loam; 10% Cover; 0.1 Furrow —x—Reclaimed Loam; 10% Cover; 0.3 Furrow
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Figure 5n: Black M esa/Kayenta M ines Sedirn ent Yield
vs. Plot Slope
0 7
0.6 •
1 0.5 -
"c =>»
§"§ 0.4 •
,,., o
If 0.3 -
1 §,
"' g 0.2 -
0.1 -
0 -
: _ . -- '.
^^-^*
- ' *"^_
. ' __. •-'*
„, - ' ' . — • — ~"~
' ~^~~~~^~ --•"""""
- *^*^ . A "
m-^^^ ..*••'"".__ --- •*' — ~~ •'""""" |
•^i. -^'^. -- -••" "" 7 ' '. , , '. . i",.
mr -I .
0 5 10 15 20 25 30 35 40
Plot Slope (percent)
• Unmined Sandy Loam; 10% Cover
•m- -Reclaimed Sandy Loam; 10% Cover
i , <::;!>li:;|; i;, Jiii i, , r
- -A- -Reclaimed Sandy Loam; 10% Cover; 0.1 Furrows
— • — Reclaimed Sandy Loam; 10% Cover; 0.3 Furrows
Fij
14^
1.2 -
? 1 -
1 f 0.8 -
We 0.6 -
1 §.
§ 0.4 -
0.2 -
C
jure 5o : Black M esa/Kayenta M ines Sedime
Yield vs. Slope Length (ft)
..-•"*"
..--"""
_.---"
^t— * -"
50 100 150 200 250 30
. Slope Length (ft)
• Unmined Sandy Loam; 10% Cover
! . . -x- - - Reclaim ed S andy Loam ; 10% Cover; 0.3 in. Furrows
nt
3 35
0
•
,,
5-50
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Development Document - Proposed Western Alkaline Coal Mining Subcategorv
Figure 5p: B lack M esa M ines Sed im ent Yield vs.
Slope Length
t
g 1.4
I
g 1-2
£
•o
G>
en
150 200
Slope Length (ft)
» Unmined Loam; 10% Cover a Reclaimed Loam; 10% Cover
«•> Reclaimed Loam; 1 0% Cover; 0.1 in. Furrow s x Reclaimed Loam; 1 0% Cover; 0.3 in. Furrow s
Figure 5q: Black Mesa/Kayenta Mines Sediment Yield vs.
Percent Ground Cover
0.45
20
40 60 80
Percentage Ground Cover
100
. Reclaimed Loam; No Cover —3—Unmined Loam; No Cover
• Reclaimed Sandy Loam; No Cover —x Unmined Sandy Loam; No Cover
120
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
5.3.5.1 NavajoMine
Model prediction results indicate that alternate sediment controls can be used to produce
sediment yields that are less than background or unmined conditions. For example, an unmined
sandy loam of 15 percent slope and 10 percent vegetative cover density produces more sediment
than a reclaimed sandy loam of 25 percent slope and a 5 percent vegetative cover density if
furrows capable of retaining 0.1 inch of rainfall are present and slope lengths are equal (Figure
5d). It is important to note that these furrows are only a temporary measure and a more
permanent reclamation technique should be implemented. An example of this would be using
rock or mulch as a ground cover.
Figure 5d also provides a comparison of pre-and postmined sandy loams. The figure
indicates that reclaimed sandy loams (postmined) with vegetation (5 percent cover) but without
furrows results in higher sediment yields than unmined areas of similar soil/sand cover for any
slope. Figure 5d also indicates that achievement of background sediment yields solely through
manipulation of slope gradient requires that the reclaimed slope gradient be significantly
reduced. For example, to maintain a reclaimed sediment yield comparable to that of an unmined
sandy loam on a 10 percent slope, the reclaimed slope not exceed 5 percent.
The effects of varying ground cover on sediment yield for sandy loams are shown in
Figure 5e. A reclaimed sandy loam site would require significantly more ground cover to
produce the same sediment yield as an unmined sandy loam site. For example, a reclaimed sandy
loam soil, with at least 60 percent ground cover would yield approximately the same amount of
sediment as unmined sandy soil with 20 percent ground cover.
Figure 5f provides a comparison of sediment yields from pre- and postmined sandy loam
sites based on slope lengths. Based solely on slope length, reclaimed slope lengths should be less
than 50 feet to maintain background sediments yields for an unmined sandy loam site with an
original slope length of 100 feet.
Figure 5g illustrates the effectiveness of furrows in reducing hillslope sediment yield.
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\ Development Document - Proposed Western Alkaline Coal Mining Subcategory
Surfaces with furrows tend to be rougher and therefore have higher Manning's n values than
surfaces without furrows. For computer modeling purposes, plots without furrows were given a
Manning's n of 0.03 and plots with furrows were given values of 0.05.
5.3.5.2 McKinley Mine
Similar to the Navajo Mine computer prediction results, Figure 5h shows that a
significant reduction in reclaimed slope gradient is required to maintain sediment yield below
background levels. Figure 5h also shows that reclaimed loam soil with 10 percent canopy cover
and furrows capable of retaining 0.1 inch of rainfall produces less sediment than an unmined
loam soil with 50 percent canopy cover. Figure 5i indicates that reduction of slope gradient by
itself would not be sufficient to reduce sediment yield below background levels with a sandy
loam soil at the McKinley Mine. A reclaimed sandy loam soil with a 50 percent canopy cover
and furrows capable of retaining 0.6 inches of rainfall will produce less sediment than an
unmined sandy loam with 10 percent canopy cover.
The average annual sediment yield for reclaimed loam soils also was compared to
background conditions for different slope lengths, percentages of ground cover and amounts of
depression storage as shown in Figures 5j, 5k, and 51. Figure 5j shows that a 300-foot long
reclaimed loam soil plot, with furrows capable of holding 0.1 inches of rainfall, produces less
sediment than an unmined 150-feet long loam soil plot. Figure 5k illustrates that a reclaimed
loam soil with at least 60 percent ground cover will yield approximately as much sediment as an
unmined loam soil with 40 percent ground cover. Figure 51 shows the effect of depression
storage and roughness on annual sediment yield. Reclaimed soils are much more sensitive to the
amount of depression storage than unmined soils. Also as can be seen from 51, a loam soil can
be temporarily reclaimed to meet the background sediment yield of an unmined loam soil with
0.1 inch of depression storage (n = 0.035).
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
5.3.5.3 Black Mesa/Kayenta Mines
1 ! ,!
Figures 5m and 5n show the sediment yield response of a loam soil and sandy loam soil
to changes in slope gradient for both pre- and post mine conditions, respectively. Both figures
• • , t " i ' i
show that a modest 3 to 5 percent reduction in slope gradient can maintain sediment yields at or
below background levels. Also shown in both figures are the effects of contour furrows on
sediment yield. Figure 5m shows that reclaiming loam soil with furrows that, are capable of
retaining at least 0.1 inch of rainfall will satisfy the requirement of producing less sediment than
the amount produced by background conditions. Reclaimed sandy loam soil requires furrows
capable of retaining 0.5 inches of rainfall to meet the background criteria as shown in Figure 5n.
'! I
Figures 5o and 5p show the same results as Figures 5m and 5n except for slope length
instead of plot slope. Figure 5o shows that for sandy loam soils, decreasing the slope length of
the reclaimed area and reclaiming with furrows may be necessary to meet background sediment
yields.
As shown in Figure 5q, for reclamation of loam and sandy loam soils that originally had
20 percent ground cover with rock mulch, a 30 percent ground cover and a 80 percent ground
cover would be necessary for the loam and sandy loam soils respectively.
5.3.5.4 Conclusions
Comparisons were made between the erosion potential of reclaimed land versus
undisturbed hillslope surfaces. In general, results of this evaluation tend to indicate that erosion
potential of reclaimed surfaces exceeds that of unmined lands, when all other conditions are held
constant. The addition of contour furrows to the land surface tends to significantly reduce
erosion potential, however such features generally last only a few years. Contour furrows can
also tend to hinder seeding and revegetation efforts.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
More permanent forms of alternative sediment control practices include:
• manipulation of the slope gradient,
• manipulation of slope length,
• modification of the density of surface cover (vegetation, mulch, etc.),
• alteration of the hillslope surface to increase roughness or depression storage, and
• enhancement of infiltrative capacity of the soil.
Evaluation of the first four sediment control alternatives listed above shows that these
alternatives generally can be used to meet the background performance standard. Depending on
the specific properties of any particular site, defined by such variables as hillslope gradient and
length, cover density, soil particle size distribution and infiltration capacity, one or more of these
measures may be required for alternative sediment control to be effective. According to this
study, the recommended procedure for evaluation of alternative sediment control requires use of
the MULTSED model to define the background conditions of runoff and sediment yield for a
range of storm conditions. Modeling of the reclaimed conditions then indicates the relative
differences in runoff/erosion response resulting from mining activities. If postmine erosion
exceeds the undisturbed erosion potential, MULTSED can be applied to evaluate the necessary
modifications to the watershed system to meet the background performance standard.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Section 6.0 References
Bridger Coal Company, 1987. Proposal for Determination of "Best Technology Currently
Available" for Alternate Sediment Control Techniques at Bridger Coal Company.
Submitted to Wyoming Department of Environmental Quality, Land Quality Division,
Cheyenne, Wyoming.
Carlson, K.E., W.R. Erickson, and R.C. Bonine, 1995. High Intensity Short Duration Rotational
Grazing on Reclaimed Cool Season Fescue/Legume Pastures: n. Forage Production, Soil
and Plant Tissue Comparisons Between Grazed and Ungrazed Pastures. In proceedings of
the American Society for Surface Mining and Reclamation 12th Annual National
Meeting, Gillette, WY, June 3-8, pp. 215-224.
Coal Age, 1998. Keystone Coal Industry Manual, Mertec PublishingrChicago, IL.
Doehring, D.O., and others, 1985. Impact of Surface Mining Sediment Control Regulation on
the Hydrologic Balance of Dryland Streams. Presented at the Second Annual Meeting of
the American Society for Surface Mining and Reclamation, Denver, CO, Oct. 8-10.
Energy Information Administration, 1995. Coal Data: A Reference, p. 57.
Energy Information Administration, 1997. Coal Industry Annual 1997. Washington DC,
DOE/EIA -0584(97).
Erickson, W.R. and K.E. Carlson, 1995. High Intensity Short Duration Rotational Grazing on
Reclaimed Cool Season Fescue/Legume Pastures: I. System Development. In
Proceedings of the American Society for Surface Mining and Reclamation 12th Annual
National Meeting, Gillette, WY, June 3-8, pp. 202-214.
Hargis, N.E. and D.C. Hartley, 1995. A Review of Reclamation and Alternate Sediment Control
at Bridger Coal Company in Southwestern Wyoming. Presented at the National Meeting
of the American Society for Surface Mining and Reclamation, Gillette, WY, June 5-8, pp.
409-415.
Heede, Burchard H., 1975. Stages of Development of Gullies in the West. Presented in Present
and Prospective Technology for Predicting Sediment Yields and Sources, U.S. Dept. Of
Agriculture, ARS-S-40, New Orleans, Louisiana.
References
6-1
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Hjemfelt, A.T., L.A. Kramer, and R.G. Spomer. 1986. Role of Large Events in Average Soil
Loss. In Proceedings of: The Fourth Federal Interagency Sedimentation Conference,
March 24-27 1986. Las Vegas, NV.
Hromadka n, Theodore V., 1996. Hydrologic Modeling for the Arid Southwest United States.
Mission Viejo, CA: Lighthouse Publications.
Kleinbaum, D.G. and L.L. Kupper, 1978. Applied Regression Analysis and Other Multivariate
Methods, Duxbury Press, Boston, MA.
Montana, Department of Environmental Quality, 1996. Montana Sediment and Erosion Control
Manual, Prepared by Roxann Lincoln, NPDES Storm Water Program, Revised May
1996.
National Oceanic and Atmospheric Administration, 1998. Climatologicai Data Annual Summary
for Montana, New Mexico, Arizona, Colorado, and Wyoming, v. 101-103& 107, no. 13.
Pennsylvania DEP, 1999. Engineering Manual for Mining Operations. Pennsylvania Bureaus of
Mining and Reclamation and District Mining Operations, Document No. 563-0300-101,
January 1999.
Peterson, M.R. and others, 1995. Application of a Watershed Computer to Assess Reclaimed
Landform Stability in Support of Reclamation Liability Release. Paper presented at the
National Meeting of the American Society for Surface Mining and Reclamation, Gillette,
WY, June 5-8.
Porterfied, George, 1972. Computation of Fluvial-Sediment Discharge. Publication No. TW13-
C3, U.S. Geological Survey, Arlington,VA.
Renard, K. G., and others, 1997. Predicting Soil Erosion by Water: A Guide to Conservation
Planning With the Revised Universal Soil Loss Equation (RUSLE). U.S. Dept. of
Agriculture, Agriculture Handbook Number 703. Washington, D.C.
Simons, Li & Associates, 1982. Design Manual for Sedimentation Control Through
Sedimentation Ponds and Other Physical/Chemical Treatment. Washington, D.C., Office
of Surface Mining.
Toy, T. J., G. R. Foster, and J. R. Galetovic, 1998. Guidelines for the Use of the Revised
Universal Soil Loss Equation (RUSLE) Version 1.06 on Mined Lands, Construction
Sites, and Reclaimed Lands. U.S. Office of Surface Mining, Denver, CO, August 1998.
U.S. Army Corp of Engineers, 1999. Hydrologic Engineering Center. HEC-6, Scour and
Deposition in Rivers and Reservoirs.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
U.S. Environmental Protection Agency, 1992. Storm Water Management for Construction
Activities, Developing Pollution Prevention Plans and Best Management Practices.
Office of Water, Publication No. EPA 832-R-92-005, September 1992.
U.S. Environmental Protection Agency, 1998. Water Quality Criteria and Standards
Plan-Priorities for the Future. Office of Water. EPA Document #822-R-98-003.
U.S. Geological Survey, 1996. Coal Resource Regions in the Conterminous United States,
Open File Report 96-279.
U.S. Mining and Reclamation Council of America, 1985. Handbook of Alternative Sediment
Control Methodologies for Mined Lands, U.S. Office of Surface Mining, Washington,
DC.
Warner, R.C. and P.J. Schwab, 1998. SEDCAD 4 for Windows 95 & NT-Design Manual and
User's Guide. Civil Software Design, Ames, IA.
Water Engineering & Technology, Inc., 1990. Determination of Background Sediment Yield and
Development of a Methodology for Assessing Alternative Sediment Control Technology
at Surface Mines in the Semi-arid West. Fort Collins, CO.
Western Coal Mining Work Group, 1999a. Technical Information Package: Western Alkaline
Mining Subcategory. Prepared for the Western Coal Mining Work Group by Habitat
Management, Inc., Littleton, CO, January 1999.
Western Coal Mining Work Group, 1999b. Data Submittal: Western Alkaline Mining
Subcategory. Washington, D.C. (Data in Section 3.3.2 of Coal Industry Record)
Western Coal Mining Work Group, 1999c. Western Alkaline Mining Subcategory Mine
Modeling and Performance-Cost-Benefit Analysis, Draft. Prepared for the Western Coal
Mining Work Group by Habitat Management, Inc. and Water & Earth Technologies, Inc.,
Littleton, CO, June 1999.
Williams, G.P. and M.G. Wolman, 1984. Downstream Effects of Dams on Alluvial Rivers.
U.S. Geological Survey Professional Paper 1206, U.S. Government Printing Office,
Washington, D.C.
Wilson, B.N., B.J. Barfield, A.D. Ward, and ID. Moore. 1984. A Hydrology and Sedimentology
Watershed Model, Part I: Operational Format and Hydrologic Component. Transactions
of the ASAE 27(5): 1370-1377.
References
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix A: Wyoming Coal Rules and Regulations, Chapter IV
Appendix A
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Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
CHAPTER 4
ENVIRONMENTAL PROTECTION PERFORMANCE STANDARDS
FOR SURFACE COAL MINING OPERATIONS
Section 1. General.
This Chapter sets forth the environmental protection performance standards applicable to
all coal mining operations. No mining operation shall be conducted except in compliance with
the requirements hereof.
Section 2. General Environmental Protection Performance Standards.
(a)
Land uses.
(i) Reclamation shall restore the land to a condition equal to or greater than
the "highest previous use." The land, after reclamation, must be suitable for the previous use
which was of the greatest economic or social value to the community area, or must have a use
which is of more economic or social value than all of the other previous uses.
(ii) Operators are required to restore wildlife habitat, whenever the
Administrator determines that this restoration is possible, on affected land in a manner
commensurate with or superior to habitat conditions which existed before the land became
affected, unless the land is private and the proposed use is for a residential or agricultural purpose
which may preclude its use as wildlife habitat.
(iii) Water impoundments used for recreational purposes shall be constructed
in accordance with the statutes and (g) of this Section. Recreational lands, other than water
impoundments, represent changes in the land which may or may not be suitable for wildlife
habitat.
(b) Backfilling, grading and contouring.
(i) Rough backfilling and grading shall follow coal removal as
contemporaneously as possible based upon the mining conditions. The operator shall include
within the application for a permit to mine a proposed schedule for backfilling and grading with
supporting analysis.
(ii) Backfilled materials shall be replaced in a manner which minimizes water
pollution on and off the site and supports the approved postmining land use.
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Preparation of final graded surfaces shall be conducted in a manner that minimizes erosion and
provides a surface for replacement of topsoil that will minimize slippage.
(iii) All affected lands shall be returned to their approximate original contour,
except as authorized by a variance or exemption under Chapter 5, Sections 6 and 7, or Chapter 8, or
Chapter 9.
(iv) All spoil shall be transported, backfilled, compacted (where necessary to
insure stability or to prevent leaching) and graded to eliminate all highwalls, spoil piles, and
depressions, except that:
(A) Soil conservation techniques may be employed if they are needed to
retain moisture, minimize erosion, create and enhance wildlife habitat, and assist revegetation.
(B) Incomplete elimination of highwalls may be authorized in accordance
with Chapter 5, Section 7.
(C) Spoil may be placed on an area outside the mined-out area to restore
the approximate original contour by blending the spoil into the surrounding terrain if the spoil is
backfilled and graded on the area in accordance with the requirements of this subsection.
V .11' 'I: . J .
(v) Postmining slopes shall not exceed a slope necessary to achieve a minimum
long-term static safety factor of 1.3, to prevent slides and restore stable drainages and hillslopes.
(vi) Thin overburden. Where surface coal mining operations_are proposed to be
carried out continuously in the same limited pit area for more than one year from the day coal
removal operations begin and where the volume of all available spoil and suitable waste materials
over the life of the mine is demonstrated to be insufficient to achieve the approximate original
contour considering bulking factor and coal removal, surface mining activities shall be conducted
to use all available spoil and suitable waste materials to attain the lowest practicable stable grade,
but not more than the angle of repose, and to meet the requirements of paragraphs (ii) and (iv) above.
(vii) Thick overburden. Where the volume of spoil over the life of the mine is
demonstrated to be more than sufficient to achieve the approximate original contours considering
bulking factor, coal removal and subsidence of backfilled material, excess spoil may be placed
outside the pit area in accordance with the requirements of subsection (c).
(viii) Permanent impoundments: Where permanent impoundments are authorized
in accordance with Chapter 2, Section 2(b)(xiv), spoil that may result from the impoundment will
be handled in accordance with the requirements of this subsection.
(ix) Soft rock surface mining.
(A) If the reclamation plan does not provide for a permanent water
A-2
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
impoundment, the final pit area shall be backfilled, graded, compacted and contoured to the extent
necessary to return the land to the use specified in the approved plan. In preparation of slope
specifications in the plan, the operator shall consider an average of the measured slopes in the
immediate area of the proposed mine site. Slopes in the reclaimed area shall approximate the
premining slopes. Individual slope measurements, locations of the measurements, and the average
measurement shall be submitted with the reclamation plan. In determinations of the approximate
premining slope, the Land Quality Division may make an independent slope survey. All backfilling,
grading, and contouring will be done in such a manner so as to preserve the original drainage or
provide for approved adequate substitutes. No depressions to accumulate water will be permitted
unless approved in the reclamation plan as being consistent with the proposed future use of the land.
(B) Terraces or benches may be used only when it can be shown to the
Administrator's satisfaction that other methods of contouring will not provide the required result.
If terracing is proposed, detailed plans indicating the dimensions and design of the terraces, check
dams, any erosion prevention techniques, and slopes of the terraces and their intervals will be
required.
(C) If the reclamation plan provides for a permanent water impoundment
and this use has been approved according to the requirements outlined in the Act and these
regulations, the exposed pit areas must be sloped, graded, and contoured so as to blend in with the
topography of the surrounding terrain and provide for access and revegetation. Riprapping where
necessary to prevent erosion will be required. Sloping requirements will be as described above.
Under certain conditions wherein it can be demonstrated to the Administrator's satisfaction that the
pitwall can be stabilized by terracing or other techniques it may be permissible to leave not more
than one-half of a proposed shoreline composed of the stabilized pitwall. The remaining portion of
the shoreline must be graded and contoured so as to provide access and blend in with the topography
of the surrounding terrain. In the event that a partial pitwall is proposed as final reclamation, the
operator must submit a detailed explanation of the techniques to be used to establish the stability of
the pitwalls in his reclamation plan. At the Administrator's discretion, a study of the proposed
pitwall stabilization techniques may be required from an independent engineering company for
purposes of verifying the effectiveness of the proposed stabilization techniques. The Land Quality
Division will determine the acceptability of the proposed stabilization techniques based on this
information and an on-site inspection.
(D) Highwall retention may be considered on a case-by-case basis for
enhanced wildlife habitat. The Wyoming Game and Fish Department shall be consulted by the
applicant for need and design of the land form. Any approval under this paragraph shall be based
on a demonstration of safety, stability, environmental protection, and equal or better land use
considerations.
(c) Topsoil, subsoil, overburden, and refuse.
(i) Topsoil.
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
(A) All topsoil or approved surface material shall be removed from all
areas to be affected in the permit area prior to these areas being affected unless otherwise authorized
by the Administrator. The topsoil may be mixed with the subsoil but shall be segregated so as not
to become mixed with spoil or waste material, stockpiled in the most advantageous manner and
saved for reclamation purposes. The Administrator may authorize topsoil to remain on areas where
minor disturbance will occur associated with construction and installation activities including but
not limited to light-use roads, signs, utility lines, fences, monitoring stations and drilling provided
that the minor disturbance will not destroy the protective vegetative cover, increase erosion, nor
adversely affect the soil resource.
I , ' '!
(B) When topsoil is not promptly redistributed, the topsoil or approved
surface material shall be stockpiled on stable areas within the permit area in such a manner so as to
minimize wind and water erosion and unnecessary compaction. In order to accomplish this, the
operator shall establish, through planting or other acceptable means, a quick growing cover of
vegetation on the topsoil stockpiles. The topsoil shall also be protected from acid or toxic materials,
and shall be preserved in a usable condition for sustaining vegetation when placed over affected land.
Provided however, where long-term disturbance will occur, the Administrator may authorize the
temporary distribution of topsoil to enhance stabilization of affected lands within the permit area.
Where this is authorized, the Administrator shall find that the topsoil or subsoil capacity and
productive capabilities are not diminished, that the topsoil is protected from erosion, and will be
available for reclamation.
j ' " , .I !
(C) Reclamation shall follow mining as soon as is feasible so as to
minimize the amount of time topsoil must be stockpiled. Where topsoil has been stockpiled for more
than one year, the operator may be required to conduct nutrient analyses to determine if soil
amendments are necessary.
(D) Topsoil stockpiles shall be marked with a legible sign containing
letters not less than six inches high on all approach roads to such stockpiles. Said signs shall contain
the word "Topsoil" and shall be placed not more than 150 feet from any and all stockpiles of topsoil.
Such signs must be in place at the time stockpiling is begun.
(E) If abundant topsoil is present, and it is not all needed to accomplish
the reclamation required in the approved reclamation plan, the Administrator may approve of use
of this topsoil by this or another operator in another area for reclamation purposes.
(F) Trees, large rocks and other waste material which may hinder
redistribution of topsoil shall be separated from the topsoil before stockpiling.
1 .' " ! I ,,,i
(ii) Subsoil.
(A) Except as provided in (B), all subsoil determined by field methods or
chemical analysis to be suitable as a plant-growth medium shall be removed from all areas to be
affected and handled in accordance with the topsoil requirements of this Section.
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Appendix A
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\ Development Document - Proposed Western Alkaline Coal Mining Subcategory
(B) Upon an adequate demonstration by the operator that all or a portion
of the subsoil material is not needed to meet the revegetation and land use requirements of these
regulations, the Administrator may authorize all or a portion of the subsoil to not be used for
reclamation. The unused subsoil may then be regarded as overburden material and handled in
accordance with the requirements of this Section.
(iii) The topsoil (A and E horizons) shall be segregated from the subsoil (B and
C horizons) where the Administrator determines that this practice is necessary to achieve the
revegetation requirements of these regulations.
(iv) Before redistribution of topsoil or subsoil the regraded land shall be treated,
if necessary, to reduce potential for slippage and encourage root penetration.
(v) Topsoil, subsoil, and/or an approved topsoil substitute shall be redistributed
in a manner that:
(A) Achieves an approximate uniform, stable thickness consistent with the
approved permit and the approved postmining land uses, contours and surface water drainage
system;
growth;
(B) Prevents compaction which would inhibit water infiltration and plant
(C) Protects the topsoil from wind and water erosion before and after it
is seeded until vegetation has become adequately established; and
(D) Conserves soil moisture and promotes revegetation.
(vi) All rills and gullies which either preclude achievement of the approved
postmining land use or the reestablishment of the vegetative cover, or cause or contribute to a
violation of water quality standards for the receiving stream, shall be regraded or otherwise
stabilized. Topsoil shall be replaced and the areas shall be reseeded or replanted.
(vii) Nutrients and soil amendments in the amounts determined necessary by soil
test or field trials shall be applied to the replaced topsoil, subsoil or substitute material so that
adequate nutrient levels are available to establish the vegetative cover. Fertilizer shall be applied
at appropriate seasons and in amounts that will minimize pollution of surface waters or
groundwaters.
(viii) The Administrator may not require topsoil or subsoil replacement on
structures or within impoundments where replacement of this material is inconsistent with the
intended use and the structures are otherwise stable.
(ix) If a sufficient volume of suitable topsoil or subsoil is not available for salvage
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
or redistribution, then selected spoil material may be used as a topsoil or subsoil substitute or
supplement. The operator shall demonstrate that the resulting plant growth medium is equal to, or
more suitable for sustaining vegetation than the existing topsoil or subsoil and that it is the best
available in the permit area to support revegetation. A demonstration of the suitability of the
substitutes or supplements shall be based upon analysis of the texture, percent coarse fragments and
pH. The Administrator may require other chemical and physical analyses, field site trials, or
greenhouse tests if determined to be necessary or desirable to demonstrate the suitability of the
topsoil or subsoil substitutes or supplements.
(x) Topsoil and subsoil substitutes.
(A) Topsoil substitute stockpiles shall be segregated from topsoil and
overburden piles and shall be identified as substitute material. Identification signs shall be placed
not more than 150 feet from all stockpiles of substitute material. Such signs shall be in place at the
time stockpiling is begun.
i • ' , |
(B) If overburden is to be used in reclamation as a substitute for topsoil,
all large rocks and other waste material which may hinder redistribution shall be separated before
stockpiling.
(xi) Overburden, spoil and refuse.
: ' •' >j i,
(A) All overburden, spoil material and refuse shall be segregated from the
topsoil and subsoil and stockpiled in such a manner to facilitate the earliest reclamation consistent
with the approved reclamation plan.
: , . j
(B) Except where diversions are authorized by these regulations, all
overburden, spoil material, and refuse piles must be located to avoid blocking intermittent or
perennial drainages and flood plains in order to minimize loss and spread of material due to water
erosion. Ephemeral drainages may be blocked if environmentally sound methods for dealing with
runoff control and sedimentation are approved by the Administrator.
(I) For temporary stockpiles, material should be replaced in pits
as soon as possible consistent with the approved reclamation plan to minimize the amount of time
material is stockpiled.
(C) All topsoil shall be removed from areas to be used for piling spoil
material prior to the beginning of piling this material.
(D) The operator may be required to have analyses made of spoil material
in order to determine if it will be a source of water pollution through reaction with leaching by
surface water. If it is determined that this condition may exist, the operator shall describe proposed
procedures for eliminating this condition.
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__ Development Document - Proposed Western Alkaline Coal Mining Subcategory
(E) All overburden and spoil material that is determined to be toxic, acid-
forming or will prevent adequate reestablishment of vegetation on the reclaimed land surface, unless
such materials occur naturally on the land surface, must be properly disposed of during the mining
operation.
(F) All excess spoil shall be placed in approved excess spoil disposal sites
located within the permit area. If permanent overburden, spoil, or refuse piles have been approved
by the Administrator, they shall be:
(I) Located on moderately sloping and naturally stable areas where
placement provides for stability and prevents mass movement.
(II) Located in areas which do not contain springs, seeps, natural
or man-made drainages (excluding rills and gullies), croplands, or important wildlife habitat.
(HI) Designed, graded and contoured so as to blend in with the
topography of the surrounding terrain. Excess spoil pile sites shall not be located on an overall slope
that exceeds 20 degrees unless keyway cuts (excavations to stable bedrock), rock toe buttresses or
other special structural provisions are constructed to ensure fill stability. The operator must
demonstrate to the satisfaction of the Administrator that this material will be stable and can be
revegetated as required by this Section.
(IV) The slopes of all spoil areas must be designed so that they will
be stabilized against wind and water erosion. After the grading and contouring of these stockpiles,
topsoil or approved subsoil must be distributed over them in preparation for the revegetation
procedure. Revegetation must be completed in accordance with requirements of this Chapter. A
permanent drainage system must be established consistent with these regulations.
(G) Excess spoil may be returned to underground mine workings in
accordance with the plan approved by the Administrator and by MSHA.
(H) Excess spoil piles shall be designed using current, prudent professional
standards and certified by a qualified registered professional engineer. All piles shall be designed
and constructed in accordance with the standards of this subsection. Special structural provisions
shall be designed using prudent current engineering practices, in accordance with Chapter 2, Section
(I) Excess spoil shall be placed in a controlled manner to:
(I) Prevent pollution from leachate and surface runoff from the
fill on surface water or groundwater of the State.
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
(IT) Ensure mass stability and prevent mass movement during and
after construction and provide for stable drainages and hillslopes.
(HI) Ensure that the land mass designated as the disposal site is
suitable for reclamation and revegetation compatible with the natural surroundings and approved
postmining land use.
(J) The spoil pile shall be transported and placed in horizontal lifts in a
controlled manner, concurrently compacted as necessary to ensure mass stability and prevent mass
movement, covered, and graded to allow surface and subsurface drainage to be compatible with the
natural surroundings and ensure a minimum long-term static safety factor of 1.5. The Administrator
may limit the horizontal lifts to four feet or less as necessary to ensure the stability of the fill or to
meet other applicable requirements.
.. I .-.
(K) No water impoundments or large depressions shall be constructed on
the fill. Soil conservation techniques may be approved if they are needed to minimize erosion,
enhance wildlife habitat or assist revegetation, as long as they are not incompatible with the stability
of the fill.
(L) The foundation and abutments of the fill shall be stable under all
conditions of construction. Sufficient foundation investigation and any necessary laboratory testing
of foundation materials shall be performed in order to determine the design requirements for
foundation stability. Analyses of foundation conditions shall include the effect of underground mine
workings, if any, upon the stability of the structure.
(M) Slope protection shall be provided to minimize surface erosion at the
site. Diversion of surface water runoff shall conform with the requirements of subsection (e) of this
Section. All disturbed areas, including diversion ditches that are not riprapped, shall be vegetated
upon completion of construction.
(N) Terraces may be constructed on the outslope of the fill if required for
stability, control of erosion, to conserve soil moisture, or to facilitate the approved postmining land
use. The grade of the outslope between terrace benches shall not be steeper than 2h:lv (50 percent).
(O) Excess spoil that is toxic, acid-forming or combustible shall be
adequately covered with suitable material or treated to prevent pollution of surface and groundwater,
to prevent sustained combustion, and to minimize adverse affects on plant growth and the approved
postmining land use.
. " '• • • ' ":< : : 1' ' • ' I A:'
" : a,'' : ! ' » : ' il „ ,',ii'
(P) The Administrator may specify additional design criteria on a case-by-
case basis as necessary to meet the general requirements of this subsection.
i i " .I ' "
(Q) The fill shall be inspected for stability by a qualified registered
professional engineer or other qualified professional specialist under the direction of a professional
in i ,i i , ,1, T I ,
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~ Development Document - Proposed Western Alkaline Coal Mining Subcategory
engineer experienced in the construction of earth and rockfill embankments at least quarterly
throughout construction and during the following critical construction periods: (1) foundation
preparation, including the removal of all organic material and topsoil, (2) placement of diversion
systems, (3) installation of final surface drainage systems, and (4) final grading and revegetation.
Regular inspections by the engineer or specialist shall be conducted during placement and
compaction of the fill materials. The registered professional engineer shall promptly provide
certified reports to the Administrator which demonstrate that the fill has been maintained and
constructed as specified in the design contained in the approved mining and reclamation plan. The
report shall discuss appearances of instability, structural weakness, and other hazardous conditions.
A copy of all inspection reports shall be retained at the mine site.
(xii) Coal mine waste.
(A) Coal mine waste shall be disposed only in existing or, if new, in an
approved disposal site within a permit area. Coal mine wastes shall not be used in the construction
of dams, embankments, or diversion structures. The disposal area shall be designed, constructed and
maintained:
(I) In accordance with the excess spoil disposal requirements of
(xi)(F)-(I), and (K)-(O) above; and
(H) To prevent combustion and not create a public health hazard.
(B) Disposal of coal mine waste in excess spoil piles may be approved if
such waste is:
above;
treated); and
fill.
(I) Placed in accordance with the excess spoil requirements of (xi)
(It) Demonstrated to be nontoxic and nonacid-forming (or properly
(ffl) Demonstrated to be consistent with the design stability of the
(C) In addition to (A) above, coal mine waste piles shall meet the
following requirements:
(I) The disposal facility shall be designed to attain a minimum
static safety factor of 1.5. The foundation and abutments must be stable under all conditions of
construction.
(II) Following final grading of the waste pile, the site shall be
covered with a minimum of four feet of the best available, nontoxic, nonacid-forming and
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
noncombustible material, in a manner that directs runoff away from the waste pile. The site shall be
revegetated in accordance with this Chapter. The Administrator may allow less than four feet of
cover material based on physical and chemical analyses which show that the revegetation
requirements will be met.
(IE) Surface drainage from above the pile and from the crest and
face of the pile shall be permanently diverted around the waste in accordance with subsection (e) of
this Section. \
(IV) All coal mine waste piles shall be inspected in accordance with
the excess spoil requirements of (xi) above. More frequent inspections shall be conducted if a
danger or harm exists to the public health and safety or the environment. Inspections shall continue
until the waste pile has been finally graded and revegetated or until a later time as required by the
Administrator. If any inspection discloses that a potential hazard exists, the Administrator shall be
notified immediately, including notification of any emergency protection and remedial procedures
which will be implemented. If adequate procedures cannot be formulated or implemented, the
Administrator shall inform the appropriate emergency agencies of the hazard to protect the public
from the area.
CFR §§ 77.214 and 77.215.
(V) All coal mine waste piles shall meet the requirements of 30
(D) Dams and embankments constructed to impound coal mine waste shall
comply with the following:
; | ;l
(I) Each impounding structure shall be designed, constructed and
maintained in accordance with the requirements applicable to temporary impoundments. Such
structures may not be retained permanently as part of the approved postmining land use. Approval
by the State Engineer's Office is not required.
(E) If the impounding structure meets the criteria of 30 CFR §
77.216 (a), the combination of principal and emergency spillways shall be able to safely pass the
100-year, 6-hour design precipitation event or a storm duration having a greater peak flow.
(HI) Spillways and outlet structures shall be designed to provide
adequate protection against erosion and corrosion. Inlets shall be protected against blockage.
I | ;
(IV) Be designed so that 90 percent or more of the water stored
during the design precipitation event can be removed within ten days.
(V) Runoff from areas above the disposal facility or runoff from
the surface of the facility that may cause instability or erosion of the impounding structure shall be
diverted into stabilized diversion channels designed to meet the requirements for diversions, and
designed to safely pass the runoff from a 100-year, 6-hour design precipitation event or a storm
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
duration having a greater peak flow.
(E) The Administrator may specify additional design criteria for waste
piles or impounding structures on a case-by-case basis as necessary to meet the general performance
standards of this subsection.
(F) Coal mine waste fires shall be extinguished by the operator in
accordance with a plan approved by the Administrator and the Mine Safety and Health
Administration. The plan shall contain, at a minimum, provisions to ensure that only those persons
authorized by the operator, and who have an understanding of the procedures to be used, shall be
involved in the extinguishing operations. No burning or burned coal mine waste may be removed
from a permitted disposal area without a removal plan approved by the Administrator. Consideration
shall be given to persons working or living in the vicinity of the structure.
(G) Coal preparation plants shall be included within a permit area. Refer
to Chapter 3, Section 6 for requirements applicable to coal preparation plants.
(xiii) Acid-forming and toxic materials, and other waste.
(A) All exposed coal seams remaining after mining and any acid-forming,
toxic, and combustible materials, or any waste materials that are exposed, used or produced during
mining shall be adequately covered, within 30 days of its exposure with nontoxic, nonacid-forming
and noncombustible material, or treated. Compaction followed by burial or treatment shall be
provided to prevent pollution of surface and groundwater quality, prevent sustained combustion and
to minimize adverse effects on plant growth and postmining land uses. Such materials may be stored
in a controlled manner until final burial and/or treatment first becomes feasible as long as storage
will not result in any risk of water pollution or other environmental or public health and safety
damage. Storage, final burial and treatment shall be done in accordance with all local, State and
Federal requirements.
(B) Acid-forming or toxic material, or any other waste material capable
of polluting water, shall not be buried or stored in the proximity of a drainage channel or its flood
plain so as to cause or pose a threat of water pollution.
(C) Final burial of noncoal mine waste materials (such as grease,
lubricants, paints, flammable liquids, garbage, trash, abandoned mining machinery, lumber and other
combustible materials) and any wastes classified as hazardous shall be in a designated disposal site
authorized by the Solid Waste Management Section of the Department.
(D) Management and final burial on the permit area of solid wastes
generated by a mine mouth power plant or mine mouth coal drier shall be in accordance with this
Section and with provisions of the Solid Waste Management Rules and Regulations deemed
appropriate by the Administrator.
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
(d) Revegetation.
• • i 'i;i-
(i) The operator shall establish on all affected lands a diverse, permanent
vegetative cover of the same seasonal variety native to the area or a mixture of species that will
support the approved postminmg land use in a manner consistent with the approved reclamation
plan. This cover shall be self-renewing and capable of stabilizing the soil.
(ii) Land which did not support vegetation prior to becoming affected land
because of natural soil conditions need not be revegetated unless subsoil from such affected land will
support vegetation. The operator shall demonstrate to the Administrator's satisfaction that
revegetation or reforestation is not possible if he seeks to proceed under the provisions of the
subsection.
(iii) After backfilling, grading, and contouring and the replacement of topsoil,
and/or approved substitutes, revegetation shall be commenced in such a manner so as to most
efficiently accommodate the retention of moisture and control erosion on all affected lands to be
revegetated. In addition, any fertilizer requirements as determined on the basis of previous analysis
must be fulfilled.
(iv) Mulch or other equivalent procedures which will control erosion and enhance
soil moisture conditions shall be used on all retopsoiled areas.
(v) Seeding which is accomplished by mechanical drilling shall be on the
topographic contour, unless for safety reasons it is not practicable, or perpendicular to the prevailing
wind on flat areas. Seeding of affected lands shall be conducted during the first normal period for
favorable planting conditions after final preparation unless an alternative plan is approved. Any rills
or gullies that would preclude successful establishment of vegetation or achievement of postmining
land use shall be removed or stabilized. The species of vegetation to be used in revegetation efforts
shall be described in the reclamation plan indicating the composition of seed mixtures and the
amount of seed to be distributed on the area on a per acre basis. Seed types will depend on the
climatic and soil conditions prevailing in the permit area and the proposed use of the land after
reclamation. Species to be planted as permanent cover shall be self-renewing. Seeding rates will
depend on seed types, climatic and soil conditions and the techniques to be used in seeding.
: :\ , r , I" . ' ' ]••;
(vi) Introduced species may be used only to achieve a quick, temporary, stabilizing
cover to control erosion, or to achieve a postmining land use as approved by the Administrator.
Naturalized or nonindigenous native plant species may be included in the approved seed mixture if
they support the approved postmining land uses. The operator shall document, unless otherwise
authorized by the Administrator, the suitability of these species using data from published literature,
from experimental test plots, from on-site experience, or from other information sources.
(vii) When the approved postmining land use is for residential,
industrial/commercial, or cropland, the reclaimed area shall be stabilized, and revegetated to control
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Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
erosion unless development or cropping shall immediately occur.
(viii) For areas previously disturbed by mining and not reclaimed to the requirements
of these regulations, the areas shall, at a minimum, be revegetated to a ground cover and productivity
level existing before redisturbance and shall be adequate to control erosion.
(ix) B ond release. The bond for revegetation shall be retained for not less than ten
years after the operator has completed seeding, fertilizing, irrigation, or other work to ensure
revegetation. The bonding period shall not be affected where normal and reasonably good husbandry
practices are being followed. The,,success of revegetation shall be determined in accordance with
Section 2(d)(x) of this Chapter and paragraphs (E)-(H) below. If the Administrator approves an
alternative success standard, as allowed by Section 2(d)(x) of this Chapter, the standard shall be
based on technical information obtained from a recognized authority (e.g. Soil Conservation Service,
Agricultural Research Service, Universities, Wyoming Game and Fish Department, U.S. Fish and
Wildlife Service, etc.), or be supported by scientifically valid research. Use of an
alternative technical standard shall be supported by concurrence from State and Federal agencies
having an interest in management of the affected lands.
(x) The Administrator shall not release the entire bond of any operator until such
time as revegetation is completed, if revegetation is the method of reclamation as specified in the
operator's approved reclamation plan. Revegetation shall be deemed to be complete when: (1) the
vegetation cover of the affected land is shown to be capable of renewing itself under natural
conditions prevailing at the site, and the vegetative cover and total ground cover are at least equal
to the cover on the area before mining, (2) the productivity is at least equal to the productivity on the
area before mining, (3) the species diversity and composition are suitable.for the approved
postmining land use and the revegetated area is capable of withstanding grazing pressure at least
comparable to that which the land could have sustained prior to mining, unless Federal, State or local
regulations prohibit grazing on such lands, and (4) the requirements in (1), (2) and (3) are met for
the last two consecutive years of the bonding period. The Administrator shall specify quantitative
methods and procedures for determining whether equal cover and productivity has been established
including, where applicable, procedures for evaluating postmining species diversity and composition.
The following options or an alternative success standard approved by the Administrator are
available:
(A) The method utilizing control areas may be selected. If selected, the
control areas shall be sampled for cover, productivity, species diversity and composition in the same
season that the area to be affected is sampled for baseline data. Quantitative premining and
postmining vegetation data from the control areas shall be used to mathematically adjust premining
affected area data for climatic change. Premining affected area cover and productivity data will be
directly compared by statistical procedures to data from the reclaimed vegetation type when
evaluating revegetation success for final bond release. Species diversity and composition data will
be qualitatively or quantitatively evaluated as determined by the Administrator.
(B) The method utilizing reference areas may be selected. If selected, the
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
representativeness of the reference area is verified by a statistical comparison to the plant community
that it typifies. Postmining cover and productivity data from the reference area are directly compared
by standard statistical procedures to data from the reclaimed area when evaluating revegetation
success for final bond release. Species diversity and composition data will be qualitatively or
quantitatively evaluated as determined by the Administrator.
(C) Where the premining cover, productivity, species diversity and
composition data cannot be collected, or where the area to be affected is small and incidental to the
operation, comparison areas may be selected. For purposes of this method, postmining qualitative
and quantitative data from the comparison area are directly compared by procedures acceptable to
the Administrator to data from the reclaimed lands when evaluating success of revegetation for final
bond release.
(D) Without regard to the type of method selected, control, reference or
comparison areas should be at least two acres in size, located in areas where they will not be affected
by future mining, while serving their designated use, managed in a fashion which will not cause
significant changes in the vegetation parameters of cover, productivity, species diversity and
composition and be representative of the postmining land use.
(E) The postmining density, composition, and distribution of shrubs shall
be based upon site-specific evaluation of premining vegetation and wildlife use. Shrub reclamation
procedures shall be conducted through the application of best technology currently available.
(I) Except where a lesser density is justified from premining
conditions in accordance with Appendix A, at least 20 percent of the eligible lands shall be restored
to shrub patches supporting an average density of one shrub per square meter. Patches shall be no
less than .05 acres each and shall be arranged in a mosaic that will optimize habitat interspersion and
edge effect. Criteria and procedures for establishing the standard are specified in Appendix A. This
standard shall apply to all lands affected after August 6, 1996.
(H) Approved shrub species and seeding techniques shall be
applied to all remaining grazingland. Trees shall be returned to a density equal to the premining
conditions.
(HI) For areas containing crucial habitat, designated as such prior
to the submittal of a permit application or any subsequent amendment, or critical habitat the
Wyoming Game and Fish Department shall be consulted about, and its approval shall be required
for, minimum stocking and planting arrangements of shrubs, including species composition. For
areas determined to be important habitat, the Wyoming Game and Fish Department shall be
consulted for recommended minimum stocking and planting arrangements of shrubs, including
species composition, that may exceed the programmatic standard discussed above.
i ^ f i i
, , " !
(F) Where trees are part of the approved reclamation plan, at the time of
bond release the trees to meet the required stocking rate shall be healthy, and at least 80 percent shall
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Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
have been planted for at least eight years.
(G) Standards for the success of reforestation for commercial harvest shall
be established in consultation with forest management agencies and prior to approval of any mining
and reclamation plan that proposes reforestation. If reforestation for commercial harvest is the
method of revegetation, reforestation shall be deemed to be complete when a reasonable population
density as established in the reclamation plan has been achieved, the trees have shown themselves
capable of continued growth for a minimum period of five years following planting, and the
understory vegetation is adequate to control erosion and is appropriate for the land use goal. Quality
and quantity, vegetation cover, productivity, and species diversity shall be determined in accordance
with scientifically acceptable sampling procedures approved by the Administrator.
(H) If the Administrator approves a long-term, intensive agricultural
postmining land use, the ten year period of liability shall commence at the date of initial planting for
such long-term agricultural use.
(I) When the approved reclamation plan is to return to cropland,
reclamation shall be deemed to be complete when productive capability is equivalent, for at least two
consecutive crop years, to the premining conditions or approved reference areas. The premining
production data for the reclaimed site shall be considered in judging completeness of reclamation
whenever said data are available.
(xi) Monitoring of permanent revegetation on reclaimed areas before and after
grazing shall be conducted at intervals throughout the period prior to bond release in accordance with
the plan required by Chapter 2, Section 2(b)(vii). Monitoring results shall be presented in the annual
report.
(xii) Any plans for irrigation must be explained.
(xiii) The operator must protect young vegetative growth from being destroyed by
livestock by fencing or other approved techniques for a period of at least two years, or until the
vegetation is capable of renewing itself with properly managed grazing and without supplemental
irrigation or fertilization. The Administrator, permittee and the landowner or land managing agency
shall determine when the revegetated area is ready for livestock grazing.
(xiv) In those areas where there were no or very few noxious weeds prior to being
affected by mining, the operator must control and minimize the introduction of noxious weeds into
the revegetated areas for a period of at least five years after the initial seeding.
(e) Diversion systems and drainage control.
(i) Diversion of streams.
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
(A) All diversions shall be designed to assure public safety, prevent
material damage outside the permit area, and minimize adverse impacts to the hydrologic balance.
(B) All diversions and associated structures shall be designed, constructed,
maintained and used to ensure stability, prevent, to the extent possible using best technology
currently available, additional contribution of suspended solids to streamflow outside the permit
area, and comply with all applicable local, State and Federal rules.
(C) Permanent diversions of intermittent and perennial streams shall be
designed and constructed so as to be erosionally and geomorphically compatible with the natural
drainage system.
(D) The design and construction of all diversions for perennial or
intermittent streams shall be certified by a qualified registered professional engineer as meeting the
diversion standards of these regulations and the approved permit.
(E) When permanent diversions are constructed or stream channels
restored after temporary diversions, the operator shall:
(I) Restore, enhance where practicable, or maintain natural
riparian vegetation on the banks and flood plain of the stream;
... II , i , ':',
(II) Establish or restore the stream characteristics, including aquatic
habitats to approximate premining stream channel characteristics; and
flood plains.
(HI) Establish and restore erosionally stable stream channels and
, • • ' • ,i • i
(F) The operator shall renovate all permanent diversions in accordance
with the approved reclamation plan prior to abandonment of the permit area.
(G) When no longer needed to achieve the purpose for which they were
authorized, all temporary diversions shall be removed and the affected land regraded and
revegetated, in accordance with this Chapter. Before diversions are removed, downstream water
treatment facilities previously protected by the diversion shall be modified or removed, as necessary,
to prevent overtopping or failure of the facilities. This
requirement shall not relieve the operator from maintaining water treatment facilities as otherwise
required.
(ii) Control of discharge or drainage.
(A) Discharge from sedimentation ponds, permanent and temporary
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Appendix A
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__ Development Document - Proposed Western Alkaline Coal Mining Subcategory
impoundments, coal-processing waste dams and embankments, and diversions shall be controlled,
by energy dissipators, riprap channels, and other devices, where necessary, to reduce erosion, to
prevent deepening or enlargement of stream channels, and to minimize disturbance of the hydrologic
balance. Discharge structures shall be designed according to standard engineering design procedures.
(B) Drainage from acid-forming and toxic-forming material into ground
and surface water shall be avoided by:
(I) Identifying, burying, and treating where necessary, material
which, in the judgment of the Administrator, may adversely affect water quality if not treated or
buried;
(II) Preventing water from coming into contact with acid-forming
and toxic-forming material and other measures as required by the Administrator; and
Complying with the requirements of subsection (c)(xiii) of this
Section and such other measures deemed necessary by the Administrator to protect surface water and
groundwater.
(C) Surface water shall not be diverted or otherwise discharged into
underground mine workings unless specifically authorized by the Administrator per the requirements
of Chapter 19, Section 2(a) of these regulations.
(iii) In addition to meeting the standards of this Section, all diversions of
groundwater discharge flows shall meet the standards of Section 2(e).
(iv) Diversion systems - Unchannelized surface water and ephemeral streams.
(A) Surface water shall be diverted around the operation for the following
purposes:
(I) To control water pollution.
(D) To control unnecessary erosion.
(ffi) To protect the on-going operation.
(IV) To protect the water rights of downstream users.
(B) Temporary diversion of surface runoff or diversions used for erosion
control shall meet the following standards:
(I) In soils or other unconsolidated material, the sides of diversion
ditches shall be no steeper than IVzil.
Appendix A
A-17
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:. * i" K lB:<"
l1 ' •'! I'TR "liiSsi
Development Document - Proposed Western Alkaline Coal Mining Subcategory
(IT) In rock, the sides of diversion ditches shall not overhang.
In soils or unconsolidated materials, the sides and, in ditches
carrying intermittent discharges, the bottom shall be seeded with approved grasses so as to take
advantage of the next growing season.
(IV) Rock riprap, concrete, soil cement or other methods shall be
used where necessary to prevent unnecessary erosion.
(V) Culverts or bridges shall be installed where necessary to allow
access by the surface owner for fire control and other purposes.
(VI) Diversion ditches shall in a nonerosive manner pass the peak
runoff from a 2-year, 6-hour precipitation event, or a storm duration that produces the largest peak
flow, as specified by the Administrator.
(C) In no case shall diversion ditches discharge upon topsoil storage areas,
spoil or other unconsolidated material such as newly reclaimed areas.
(D) Permanent diversion structures shall be designed to be erosionally
stable during the passage of the peak runoff from a 100-year, 6-hour precipitation event, or a storm
duration that produces the largest peak flow, as specified by the Administrator.
(v) Diversion of intermittent and perennial streams.
(A) In no case shall spoil, topsoil, or other unconsolidated material be
pushed into, or placed below the flood level of a perennial or intermittent stream except during the
approved construction of the diversion of said stream.
(B) The Wyoming Game and Fish Department shall be consulted prior to
the approval of a diversion of a perennial or intermittent stream.
,„ . , ,, ,| , , | , ,
(C) The banks of a diverted perennial or intermittent stream shall be
protected by vegetation by planting approved species to take advantage of the next growing season.
(D) The banks and channel of a diverted perennial or intermittent stream
shall be protected where necessary by rock, riprap or similar measures to minimize erosion and
degradation of water quality. Permanent diversions shall be designed and constructed to be
erosionally stable. The design of the permanent diversion shall also be consistent with the role of
the fluvial system.
(E) Mining on the flood plain of a perennial or intermittent stream shall
not be permitted if it would cause the uncontrolled diversion of the stream during periods of high
water.
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(F) Waters flowing through or by the mining operation shall meet the
standards set by the U.S. Environmental Protection Agency and the Wyoming Water Quality
Division in regard to the effect of the operation upon such waters.
(G) If temporary, the channel and flood plain shall be designed to pass, in
a nonerosive manner, the 10-year, 6-hour precipitation event, or the capacity of the unmodified
stream channel immediately above and below the diversion, whichever capacity is greater, or a
duration having a greater peak flow, as specified by the Administrator. Cross-sections of the existing
stream above, below and within the disturbed area may be used to determine the flow capacities,
channel configuration and shape.
(H) If permanent, the channel and flood plain shall be designed to pass,
in a nonerosive manner, the 100-year, 6-hour precipitation event, or a duration having a greater peak
flow, as specified by the Administrator. Cross-sections of the existing stream above, below and
within the disturbed area may be used to determine the flow capacities, channel configuration and
shape.
(f) Sedimentation ponds.
(i) All surface drainage from affected lands excluding sedimentation ponds,
diversion ditches, and road disturbances, shall pass through a sedimentation pond(s) before leaving
the permit area. Sedimentation control devices shall be constructed prior to disturbance. The
Administrator may grant exemptions to the use of sedimentation ponds where, by the use of
alternative sediment control measures, the drainage will meet effluent limitation standards or will
not degrade receiving waters.
(ii) Where the sedimentation pond(s) results in the mixing of drainage from
affected lands with the drainage from undisturbed areas, the permittee shall comply with the
applicable effluent limitation standards for all of the mixed drainage where it leaves the permit area.
(iii) Sedimentation ponds shall be designed and constructed to comply with the
applicable requirements of subsection (g)(iv-vii) of this Chapter. They shall be located as near as
possible to the affected lands and out of intermittent or perennial streams; unless approved by the
Administrator.
(iv) Sedimentation ponds shall be operated and maintained to comply with the
requirements of the Water Quality Division and the State Engineer's Office and satisfy the following
requirements:
(A) Chemicals that will harm fish, wildlife, and related environmental
values shall not be used for flocculation or other water treatments or if used these ponds will be
protected.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
'' '' ' ' ' I1 ' ' . li' ' r";'
(B) Sedimentation ponds shall be designed and maintained to contain
adequate sediment storage as determined by acceptable empirical methods.
precipitation event.
(C) Sluicing of collected sediments shall be prevented for the design
(D) All areas disturbed by the construction of the sedimentation pond shall
be revegetated as soon as practicable to reduce erosion.
(v) The design, construction, and maintenance of a sedimentation pond or other
sediment control measures in accordance with this subsection shall not relieve the operator from
compliance with applicable effluent limitation standards of the Water Quality Division.
(vi) Sediment ponds shall be maintained until removal is authorized by the
Division and the affected lands have been stabilized and initial vegetation established
in accordance with the approved reclamation plan and the requirements of this Chapter. In no case
shall sediment ponds treating reclaimed lands be removed sooner than two years after the last
augmented seeding.
(vii) Sediment control measures for affected lands. Appropriate sediment control
measures shall be designed, constructed, and maintained using the best technology currently
available to prevent additional contributions of sediment to streamflow or to runoff outside the
affected land. Such measures may consist of limiting the extent of disturbed land and stabilizing,
diverting, treating or otherwise controlling runoff.
: ' ' • • '•• ! • • I '?'
(g) Permanent and temporary water impoundments.
(i) Permanent water impoundments are prohibited unless authorized by the
Administrator on the basis that:
!
(A) The impoundment and its water quality and quantity will support or
constitute a postmining use equal to or greater than the highest previous use of the land.
(B) Discharge of water, if any, from the impoundment shall not degrade
the quality of receiving waters.
(C) The surface landowner, if different from the mineral owner, has
consented to the impoundment.
(ii) Permanent water impoundments. Permanent water impoundments shall be
constructed in accordance with the following requirements:
(A) Dams must contain an overflow notch and spillway so as to prevent
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failure by overfilling and washing. Overflow notches and spillways must be riprapped with rock or
concrete to prevent erosion.
(B) The slopes around all water impoundments must be gentle enough so
as not to present a safety hazard to humans or livestock and so as to accommodate revegetation.
Variations from this procedure may be approved by the Administrator based on the conditions
present at the individual locality.
(C) Mineral seams and other sources of possible water contamination
within the impoundment area must be covered with overburden or stabilized in such a manner to
prevent contamination of the impounded water.
(D) Bentonite or other mire-producing material within the impoundment
basin shall be removed or covered with materials which will prevent hazards to man or beast.
(iii) The phrase "major impoundment" shall mean any structure impounding water,
sediment or slurry:
(A) To an elevation of 20 feet or more above the upstream toe to the crest
of the emergency spillway; or
(B) To an elevation of five feet above the upstream toe of the structure and
has a storage volume of 20 acre-feet or more; or
(C) Which will be retained as part of the postmining land use, and:
(I) Has an embankment height greater than 20 feet as measured
from the downstream toe of the embankment to the top of the embankment; or
(IT). Has an impounding capacity of 20 acre-feet or greater.
(iv) The design, construction and maintenance of permanent and temporary
impoundments shall be approved by the State Engineer's Office. In addition, the following design
and construction requirements shall be applicable:
(A) The design of impoundments shall be certified by a qualified registered
professional engineer as designed to meet the requirements of this part and the applicable
requirements of the State Engineer, using current, prudent engineering practices. For major
impoundments, the certification also shall be filed with the State Engineer.
(B) The vertical portion of any remaining highwall shall be located far
enough below the low water line along the full extent of highwall to provide adequate safety and
access for the proposed water users.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
(C) Faces of embankments and surrounding areas shall be vegetated,
except that faces where water is impounded may be riprapped or otherwise stabilized in accordance
with accepted design practices, or where appropriate, Water Quality Division rales and regulations.
,.. ,., , .. ..j , ,
(D) The embankment, foundation, and abutments for all impoundments
shall be designed and constructed to be stable. For any major impoundment or any impoundment
which may present a danger to life, property or the environment, the Administrator shall require
sufficient foundation investigations and laboratory testing to demonstrate foundation stability, and
shall require a minimum static safety factor of 1.5 for the normal pool with steady seepage saturation
conditions, and a seismic safety factor of at least 1.2.
(E) All vegetative and organic materials shall be removed and foundations
excavated and prepared to resist failure. Cutoff trenches shall be installed if necessary to ensure
stability.
' . r ,! I "
(F) All impoundments shall be inspected regularly during construction and
immediately after construction by a qualified registered professional engineer or qualified
professional specialist under the direction of a qualified professional engineer. These individuals
shall be experienced in impoundment construction. Immediately following each inspection a report
shall be prepared and certified by the engineer describing the construction work observed and its
conformance with the approved designs. All inspection reports shall be retained at the mine site and
submitted in the annual report to the Administrator.
i ' ' \
(G) After completion of construction and until final bond release or
removal, all impoundments shall be inspected annually by a qualified registered professional
engineer, or by a qualified professional specialist under the direction of the qualified professional
engineer. These individuals shall be experienced in impoundment construction. Immediately
following each inspection a report shall be prepared and certified by the engineer describing:
instrumentation;
(I) Existing and required monitoring procedures and
(II) Depth and elevation of any impounded water;
(HI) Existing storage capacity;
(IV) Aspects of the dam that may affect its stability or present any
other hazardous condition; and
(V) If the impoundment is being maintained in accordance with
the approved design and this Chapter. All annual inspection reports shall be retained at the mine site
and annually submitted to the Administrator.
i
(H) In addition to the post-construction annual inspection requirements
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contained in paragraph (G) immediately above, all impoundments must be inspected during each of
the intervening calendar quarters by a qualified individual designated by the operator. These
inspections shall look for appearances of structural weakness and other hazardous conditions.
(I) Those impoundments subject to 30 CFR § 77.216 shall also be
inspected in accordance with 30 CFR § 77.216-3.
(J) If any examination of inspection discloses that a potential hazard
exists, the operator shall promptly inform the Administrator of the finding and of the emergency
procedures formulated for public protection .and remedial action. If adequate procedures cannot be
formulated or implemented the Administrator shall be notified immediately. The Administrator shall
then notify the appropriate agencies that other emergency procedures are required to protect the
public.
(K) Impoundments meeting the criteria of 30 CFR § 77.216(a) shall
comply with the requirements of 30 CFR § 77.216. The plan required to be submitted to the District
Manager of MSHA under 30 CFR § 77.216 shall also be submitted to the Administrator as part of
the permit application.
(v) The design precipitation event for the spillways for temporary water
impoundments shall be a 25-year, 6-hour precipitation event, or a storm duration having a greater
peak flow, as may be required by the Administrator.
(vi) The design precipitation event for the spillways for a permanent impoundment
shall be a 100-year, 6-hour precipitation event, or a storm duration having a larger peak flow, as may
be required by the Administrator.
(vii) Before abandoning an area or seeking bond release, the operator shall ensure
that all temporary structures are removed and reclaimed, and that all permanent structures are
renovated, if necessary to meet the requirements of this subsection and to conform to the approved
reclamation plan.
(viii) Tailings impoundments.
(A) Impoundments to contain mill tailings or slurry tailings shall be
constructed in accordance with established engineering principles and shall be approved by the
Wyoming State Engineer's Office. A copy of the State Engineer's approval shall be attached to the
application.
(B) Reclamation of tailings impoundments shall be accomplished by
removal and storage of all topsoil present within the tailings basin. After termination of operations,
the topsoil shall be replaced and revegetated in accordance with these rules and regulations. If other
methods of reclamation and stabilization against wind and water erosion are found to be necessary
because of natural conditions, this must be stated and described subject to the Administrator's
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.1 • S • .'"I"
approval.
(h) Protection of Groundwater Recharge Capacity - The recharge capacity of the
reclaimed lands shall be restored to a condition which:.
(i) Supports the approved postmining land use;
(ii) Minimizes disturbances to the prevailing hydrologic balance in the permit area
and in adjacent areas; and
' •• : . -:. • 1, • •• . ] •'('
(iii) Provides a rate of recharge that approximates the preminmg recharge rate.
(i) Surface water and groundwater quality and quantity shall be monitored until final
bond release to determine the extent of the disturbance to the hydrologic balance. Monitoring shall
be adequate to plan for modification of surface mining activities, if necessary, to minimize adverse
affects on the water of the State. The operator is responsible for properly installing, operating^
maintaining and removing all necessary monitoring equipment. In addition, the operator is
responsible for conducting monitoring in accordance with the approved monitoring plan, and
submitting all routine monitoring results to the Administrator at least annually. Routine monitoring
results shall also be maintained on-site and available to the Director's designated authorized
representative, and shall be reasonably current. Noncompliance results for NPDES discharges shall
be promptly reported by the operator to the Water Quality Division Administrator. The operator
shall promptly report all other noncompliance results to the Land Quality Division Administrator and
shall, after consultation with the Administrator, implement appropriate and prompt mitigative
measures for those noncompliance situations determined to be mining caused. The monitoring
system shall be based on the results of the probable hydrologic consequences assessment and shall
include:
(i) A groundwater monitoring program to determine:
p .'i1.. i I.1;;
(A) Infiltration rates, subsurface flows, and storage characteristics of the
reclaimed land and adjacent areas;
lands; and
(B) The effects of reclamation on the recharge capacity of the reclaimed
(C) Suitability of groundwater for current and approved postmining land
uses.
(ii) A surface water monitoring program which includes monitoring of surface
water flow and quality from affected lands including those that have been graded and stabilized.
Results of the monitoring will be used to demonstrate that the quality and quantity of runoff from
affected lands with or without treatment will minimize disturbance to the hydrologic balance. Water
quality monitoring results for discharges other than those authorized by Water Quality Division shall
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be reported whenever results indicate noncompliance with effluent limitation standards or
degradation of the quality of receiving water shall be reported immediately. Monitoring results shall
be available for inspection at the mine site.
(j) Roads and other transportation facilities.
(i) General standards for all transportation facilities.
(A) Roads and railroads. Constructed or upgraded roads and railroad spurs
shall be included within the permit area from that point that they provide exclusive service and shall
be covered by a reclamation bond.
(B) Roads shall not be constructed up a stream channel or so close that the
material shall spill into the channel, unless specifically approved by the Administrator.
(C) Streams shall be crossed at or near right angles unless contouring down
to the streambed will result in less potential stream bank erosion. Structure of ford entrances and
exits must be constructed to prevent water from flowing clown the roadway.
(D) Drainage control structures shall be used as necessary to control runoff
and to minimize erosion, sedimentation and flooding. Drainage facilities shall be installed as road
construction progresses.
(E) Culverts shall be installed at prominent drainageways, or as required
by the Administrator. Where necessary, culverts must be protected from erosion by adequate rock,
concrete or riprap. Culverts and drainage pipes shall be constructed to avoid plugging, collapsing,
or erosion at inlets and outlets.
(F) Trees and vegetation may be cleared only for the essential width
necessary to maintain slope stability and to serve traffic needs.
maintained.
(G) Access, haul roads and drainage structures shall be routinely
(H) Exemptions concerning roads.
(I) If approval is obtained from the surface landowner to leave a
road unreclaimed, an operator may request in writing to the Land Quality Division that a road be
permitted to remain unreclaimed. The operator must furnish proof of the surface landowner's
approval. Final decision of road reclamation will be made by the Land Quality Division
Administrator.
(IT) In the event that the surface landowner, a city or town, another
agency of the State of Wyoming or an agency of the United States government has requested that a
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road not be reclaimed, no bond shall be required of the applicant for the reclamation of the road and
reclamation of the road shall not be required; provided, however, that the Administrator receives a
copy of the written request from the surface owner, city or town, or agency of the State or Federal
Government, for retention of the road.
(ii) General performance standards for haul roads, access roads or light-use roads:
(A) Roads shall be located on ridges or on the most stable available slopes
to minimize erosion, sedimentation and flooding. All exposed surfaces shall be stabilized in
accordance with current, prudent engineering practices.
(B) Acid or toxic-forming substances shall not be used in road surfacing.
• (C) To the extent possible using the best technology currently available,
roads shall not cause damage to fish, wildlife, and related environmental values and shall not cause
additional contributions of suspended solids to streamflow or to runoff outside the affected land or
permit area. Any such contribution shall not be in excess of limitations of State or Federal law or
degrade the quality of receiving water.
.; - j. . • \.'*.
!' | I \!
(D) The normal flow of water in streambeds and drainage channels shall
not be significantly altered. Damage to public or private property shall be prevented or controlled.
1.3.
(E) • All embankments shall have, at a minimum, a static safety factor of
(F) The design and construction or reconstruction shall incorporate
appropriate limits for grade, width, surface materials, surface drainage control, culvert placement,
culvert size, and such other design criteria required by the Administrator to ensure environmental
protection and safety appropriate for the planned duration and use.
(G) All roads shall be maintained and/or repaired, if damaged, to meet the
performance standards of this subsection.
(H) All roads shall be closed to vehicular travel when no longer needed
and reclaimed in accordance with this Chapter, unless the road is retained for use under an approved
postmining land use.
(iii) Performance standards for haul roads and access roads.
(A) Design and construction: The design and construction or
reconstruction of haul roads and access roads shall be certified by a registered professional engineer
as meeting the requirements of this subsection; current, prudent engineering practices; and any
design criteria required by the Administrator.
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(B) Stream fords are prohibited unless they are specifically approved by
the Administrator as temporary routes during periods of construction.
(C) Drainage.
(I) Haul and access roads shall be designed, constructed, or
reconstructed and maintained with drainage control structures capable of safely passing the runoff
from a 10-year, 6-hour precipitation event, or a storm duration having a greater peak flow, unless
otherwise specifically approved by the Administrator. The drainage control system shall include,
but not be limited to bridges, culverts, ditches, cross drains, and ditch-relief drains.
(II) All drainage pipes or culverts shall be constructed and
maintained to avoid plugging, collapse and erosion at inlets and outlets.
(IE) All culverts shall be designed, constructed, and maintained to
sustain the vertical soil pressure, passive resistance of the foundation, and the weight of vehicles to
be used.
(IV) Ephemeral (shown on a USGS 7.5 minute series quad),
intermittent or perennial streams shall not be altered or relocated for road construction or
reconstruction without approval from the Administrator, and then, only if the natural channel
drainage is not blocked except during periods of low flow or when flow has been acceptably diverted
around the site, there is no significant damage to hydrologic balance, and there is no adverse impact
on adjoining landowners.
(V) Drainage ditches shall be designed to prevent uncontrolled
drainage over the road surface and embankment. Trash racks and debris basins shall be installed in
the drainage ditches where debris from the drainage area may impair the functions of drainage and
sediment control structures.
(VI) Except as provided in (B) above, drainage structures which are
used for stream channel crossings shall be made using bridges, culverts, or other structures designed,
constructed, and maintained using current, prudent engineering practices.
(D) Surfacing: Roads shall be surfaced with rock, crushed gravel, asphalt,
or other material sufficiently durable for the anticipated volume of traffic and weight and speed of
vehicles to be used.
(E) Maintenance: Routine maintenance shall include repairs to the road
surface, blading, filling potholes and adding replacement gravel or asphalt. It shall also include
revegetation, brush removal, and minor reconstruction of road segments as necessary.
(iv) Railroad and other transportation and mine facilities.
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
*'2,. ! ' ,. i;i !'' •' ' ' ,,".'' .''' ' '' ' '" , .M ' i ,; ' ' " ;i '"''i'
(A) Railroad loops, spurs, sidings, surface conveyor systems, chutes, aerial
tramways, or other transportation and mine facilities shall be designed, constructed, or reconstructed,
and maintained and the area restored to:
(I) Prevent, to the extent possible using the best technology
currently available, damage to fish, wildlife, and related environmental values, and additional
contributions of suspended solids to streamflow or runoff outside the affected land and permit area.
Any such contributions shall not be in excess of limitations of State or Federal law or degrade the
quality of receiving water.
quality and quantity.
(II) Control and minimize diminution or degradation of water
(DTI Control and minimize erosion and siltation.
' • , , ! j . 1 . "
(TV) Control and minimize air pollution
(V) Prevent damage to public or private property.
i,, „ , „„ , ,j „ „
i
(B) Railroads and other transportation and mine facility areas shall be
reclaimed when no longer needed for the operation in accordance with the requirements of this
Chapter.
(k)
Time schedule.
(i) Reclamation must begin as soon as possible after mining commences and
must continue concurrently until such time that the mining operation is terminated and all of the
affected land is reclaimed. If conditions are such that final reclamation procedures cannot begin until
the mining operation is completed, this must be explained in the reclamation plan. A detailed time
schedule for the mining and reclamation progression must be included in the reclamation plan. This
time schedule shall:
(A) Apply to reclamation of all lands to be affected in the permit area;
(B) Designate times for backfilling, grading, contouring and reseeding;
(C) Be coordinated with a map indicating the areas of progressive mining
and reclamation;
(D) Establish reclamation concurrently with mining operations, whenever
possible. If not possible, the schedule shall provide for the earliest possible reclamation consistent
with the orderly and economic development of the property; and
, , j
-1' •: :,! . ' • ,' I ".,•.• ,..'11' , ,l|i • I, 'II
(E) If the Administrator approves a schedule where reclamation follows
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the completion of mining, describe the conditions which will constitute completion or termination
of mineral production.
(1) Unanticipated conditions.
(i) An operator encountering unanticipated conditions shall notify the
Administrator as soon as possible and in no event more than five days after making the discovery.
(ii) An unanticipated condition is any condition encountered in a mining operation
and not mentioned by the operator in his mining or reclamation plan which may seriously affect the
procedures, timing, or outcome of mining or reclamation. Such unanticipated conditions include but
are not limited to the following:
(A) The uncovering during mining operations of any acid-forming,
radioactive, inflammable, or toxic materials which must be burned, impounded, or otherwise
disposed of in order to eliminate pollution or safety hazards.
(B) The discovery during mining operations of a significant flow of
groundwater in any stratigraphic horizon.
(C) The occurrence of slides, faults, or unstable soil and overburden
materials which may cause sliding or caving in a pit which could cause problems or delays with
mining or reclamation.
(D) The occurrence of uncontrolled underground caving or subsidence
which reaches the surface, causing problems with reclamation and safety hazards.
importance.
j
(E) A discovery of significant archaeological or paleontological
(iii) In the case of the uncovering of hazardous materials, the operator shall take
immediate steps to notify the Administrator and comply with any required measures to eliminate the
pollution or safety hazard. Under all conditions the operator must take appropriate measures to
correct, eliminate, or adapt to an unanticipated condition before mining resumes in the immediate
vicinity of that condition.
(m) Disposal of buildings and structures.
(i) All buildings and structures constructed, used or improved by the operator
must be removed or dismantled unless it can be demonstrated to the Administrator's satisfaction that
the buildings or structures will be of beneficial use in accomplishing the proposed use of the land
after reclamation or for environmental monitoring.
(ii) If the operator does not wish to remove certain buildings or facilities, he must
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
" ,i " !! „
. - . .1 • • » . ., -.
obtain the written consent of the surface landowner to leave the buildings or facilities intact. The
operator must make a request in writing, providing written proof of the above to the Land Quality
Division, that the buildings or facilities be permitted to remain intact.
, • ] ,! „„
(n) All support buildings, including loading and storage facilities, plants, sheds, shops
and other buildings shall be designed, constructed or reconstructed and located to prevent or control
erosion, pollution, and damage to public or private property, fish, wildlife, and related environmental
values. Ajl operations shall be conducted so as to minimize disruption of any services provided by
facilities located on, under or through the permit area, unless otherwise approved by the
Administrator or owner of such facilities.
(o) Signs and markers. Uniform and durable signs and markers of an adequate size shall
be posted by the operator at those points applicable to the areas or activities to which they pertain.
Such signs and markers shall include mine and permit identification signs, perimeter markers, buffer
zone markers, blasting signs and soil markers. The operator shall place and maintain all signs and
markers prior to commencement and until the completion of the activities to which they pertain,
which, for mine and permit identification signs, shall be at the time the bond is released.
(p) Drilled holes and other exposed underground openings: Plugging, sealing and
capping of all drilled holes except those used solely for blasting or developmental drill holes which
will be mined through within one year shall meet the requirements of Chapter 14. Developmental
drilling shall meet the plugging and sealing requirements of W.S. § 35-11-404, where necessary.
Temporary sealing and use of protective devices may be approved by the Administrator if the hole
will be used for returning coal-processing waste or water to underground workings or monitoring
groundwater conditions, and shall be used, at a minimum, for developmental drilling. Other exposed
underground openings shall be properly managed as required by the Administrator to prevent access
to mine workings and to keep acid or other toxic drainage from entering ground or surface water.
! ' " ". ' " '" i "....
(i) With the prior approval of the Administrator and the State Engineer, wells
may be transferred to another party for further use. The permittee shall remain responsible for the
proper management, of the well until final bond release.
(q) Air resources protection. All exposed surface areas shall be protected and stabilized
to effectively control erosion and air pollution attendant to erosion.
! , !|
(r) Fish and wildlife performance standards.
(i) An operator shall, to the extent possible using the best technology currently
available and consistent with the approved postmining land use, minimize
disturbance and adverse impacts on fish, wildlife, and related environmental values, and achieve
enhancement of such resources where practicable, which activities shall include:
(A) Properly construct, locate and operate roads and power lines, including
proper design of power lines to avoid electrocution of raptors.
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(B) Prevent access to areas such as roadways or ponds with hazardous
materials, to avoid damage to wildlife without limiting access to known important routes.
(C) Afford protection, restore and enhance where practicable important
habitats to fish and wildlife. This shall include, but is not limited to, wetlands and riparian
vegetation along rivers and streams and bordering ponds and lakes.
(D) Select plant species with shrubs well represented, which will enhance
the nutritional and cover aspects offish and wildlife habitat, where such habitat is identified as part
of the postmining use, and distribute the reestablished habitat in a manner which includes a diversity
and interspersion of habitats, optimizes edge effect, cover and other benefits for fish and wildlife,
and is consistent with Section 2(d)(x)(E).
(E) Promptly report to the regulatory authority any species or critical
habitat of such species listed as threatened or endangered, or any golden or bald eagle nest in or
adjacent to the permit area, which was not reported or investigated in the permit application. Upon
notification the Administrator shall consult with the Wyoming Game and Fish Department and the
U.S. Fish and Wildlife Service and, after consultation, shall identify whether and under what
conditions the operator may proceed.
(F) Where the postmining land use is for cropland, to the extent not
inconsistent with this intended use, operators shall restore habitat types to break up large blocks of
monocultures.
(ii)
Stream buffer zone.
(A) No land within 100 feet of a perennial or intermittent stream shall be
affected unless the Administrator specifically authorizes such activities closer to or through such a
stream upon a finding that:
(I) Surface mining activities will not cause or contribute to the
violation of applicable state or federal water quality standards, and will not adversely affect the water
quantity and quality or other environmental resources of the stream; and
(II) If there will be a temporary or permanent stream-channel
diversion, it will comply with all stream diversion requirements.
(B) The area not to be affected shall be designated a buffer zone, marked
in the field and on the mine plan map.
(iii) No surface mining activity shall be conducted which is likely to jeopardize
the continued existence of endangered or threatened species listed by the State or the Secretary of
the Interior or which will result in the destruction or adverse modification of designated critical
habitats of such species in violation of the Endangered Species Act (16 U.S.C. 1531 et seq.). No
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
'i i ,:•'!., . ' ' ' ,','•' i1 | ' , ' ,'! I K
surface mining activity shall be conducted in a manner which would result in the unlawful taking
of a bald or golden eagle, its nest, or any of its eggs. The Administrator shall consult with the State
arid Federal Fish and Wildlife Agencies to identify whether and under what conditions the operation
may continue under this provision.
I „ , I !• ' :
(iv) The operator shall perform periodic surveys, in the level of detail and for those
areas as determined by the Administrator, in accordance with Appendix B of these rules and
regulations.
11 „ , , | , ,
i
(s) Slides and other damage. Where instability may exist in backfill materials, an
undisturbed natural barrier shall be provided to prevent slides and erosion, beginning at the elevation
of the lowest coal seam to be mined and extending from the outslope for such distance as may be
determined by the Administrator.
(t) Only those operations designed to protect disturbed surface areas and which result
in improved resource recovery, abatement of water pollution, or elimination of hazards to the public
shall be conducted within 500 feet of an active or abandoned underground mine. Approval for such
operation shall be obtained from MSHA for operations proposed to be conducted within 500 feet of
an active underground mine. The Administrator shall specifically approve operations proposed to
be conducted within 500 feet of an abandoned underground mine.
i , '
(u) Cessation of operations. When it is known that a temporary cessation of operations
will extend beyond 30 days, the operator shall submit to the Administrator that information required
in an annual report.
(v) The operator shall conduct operations so as to maximize the utilization and
conservation of the solid fuel resource being recovered so that reaffecting the land in the future can
be minimized.
(w) The operator shall conduct all operations in such a manner as to minimize disturbance
of the hydrologic balance within the permit and adjacent areas, to prevent material damage to the
hydrologic balance outside the permit area, to assure the protection or replacement of water rights,
and to support approved postmining land uses in accordance with the terms and conditions of the
approved permit and the performance standards of this Chapter. Mining and reclamation practices
that minimize water pollution and changes in flow shall be used in preference to water treatment.
A-32
Appendix A
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix B: Wyoming Guideline No. 15
(HP/2-90, Riles Update/8-94)
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix B
lift: »„, ,':,,;,! ,5;! i •! 'i,;n<, , Illr l»' t li,; , i,1" il""" ,'iJiiJ " Ji'B I li"" ,1,
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
WYOMING DEPARTMENT OF ENVIRONMENTAL QUALITY
LAND QUALITY DIVISION
GUIDELINE NO. 15
ALTERNATIVE SEDIMENT CONTROL MEASURES
This document is a guideline only. Its contents are not to be interpreted by applicants, operators,
or LQD staff as mandatory. If an operator wishes to pursue other alternatives, he or she is encouraged to
discuss these alternatives with the LQD staff.
I. INTRODUCTION
This guideline identifies specific sediment control measures that may be used in addition to or in
place of sedimentation ponds. Operators should note that alternative sediment control design
requirements are minimal for areas less than 30 acres. Monitoring requirements are also minimal for
small ephemeral receiving streams (drainage areas less than 0.5 square miles). Land Quality Division
(LQD) will rely on field inspections of small areas, focusing on construction and maintenance to ensure
their effectiveness.
These recommendations do not constitute the only acceptable alternative sediment control
techniques. LQD intends to maintain flexibility so that they can evaluate sediment control systems not
envisioned in this guideline. The final sediment control system should conform to the standards
described herein for design, construction, maintenance, and monitoring.
Even where sedimentation ponds are constructed, alternative sediment control changes can be
used to minimize sediment delivery to ponds and thereby decrease the frequency of pond maintenance.
Alternative techniques are especially applicable to large reclaimed watersheds, where erosion must be
controlled before a downstream pond is eliminated.
II. Objective of Alternative Sediment Control Measures (ASCM's)
Alternative sediment control measures are presented as an option other than the use of
sedimentation ponds in the WDEQ/LQD Coal Rules and Regulations when it can be demonstrated that
they "will not degrade receiving waters" (Chapter IV, Section 2.(f)(I)). Receiving waters are defined by
the LQD as:
1. Any unimpounded and undisturbed or permanently reclaimed stream outside of the
permit area that is within three (3) channel miles downstream of an area controlled by an
ASCM; or
2. Any unimpounded and undisturbed or permanently reclaimed stream within the permit
area downstream of an ASCM.
As stated in Chapter IV, Section 2.(f)(vii), "Appropriate sediment control measures shall be
designed, constructed, and maintained using the best technology currently available to prevent additional
contributions of sediment to streamflow or to runoff outside the affected land". Also, a surface water
Appendix B B-l
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V •:">• 'I! "I1. '•;'« J'tW; *•»','
Development Document - Proposed Western Alkaline Coal Mining Subcategory
:" :;! '' ; • .:! "••:• • . • ! !l|i!
monitoring program "...will be used to demonstrate that the quality and quantity of runoff from affected
lands.-.will minimize disturbance to the hydrologic balance". (Chapter IV, Section 2.(I)(ii)).
These regulations suggest that there is a design/maintenance standard, best technology
currently available (BTCA), a performance standard, non-degradation of receiving waters, and a
verification standard, demonstrable monitoring program. ASCM's should be designed such that it can
be demonstrated that sediment yields are not greater than background levels.
DDE. Best Technology Currently Available (BTCA)
A. Elements of BTCA.
The design methods, construction techniques, maintenance practices and monitoring
system all contribute to a system that can be considered BTCA.
' » • ' . ' -' ! , • 1 '•!
B. Determination of BTCA.
•II ,, | , i :
1. BTCA will be determined on a case by case basis. BTCA determinations will be
based on the type of disturbance, the size of the disturbance and the length of
time the ASCM will be in place. The LQD will not require the same ASCM
sophistication on, for example, small temporary topsoil stockpiles or topsoil
stripping areas as they will for a permanently reclaimed watershed. The
determination of BTCA will be based on how effective the ASCM is at:
a. Preventing soil detachment and erosion, using slope erosion control
practices.
b. Retaining sediment as close as possible to its point of origin, using on-
slope and in-channel sediment trapping structures.
It is preferable to use effective slope erosion control practices where possible.
Sediment traps should constitute a second line of defense.
2. The LQD realizes that many technologies currently exist that can be considered
the "best" technology. New technologies may be developed in the near future
that may provide a higher degree of erosion protection than is "currently"
available.
IV. Design of ASCM's
ASCM's can be considered for disturbed or reclaimed areas that are not within one-half mile
(channel distance) of any class I, n, or HI stream. (These classes are defined in the WDEQ/WQD Rules
and Regulations, Chapter I, Section 4). Small areas (less than 30 acres) located within one half mile of a
class I, n, or in stream, may be protected using ASCM's, subject to the discretion of the LQD
administrator.
•••• .' • • • •.•:•• '• I • •• "• !":
A. Designing ASCM's for Small Areas (less than 30 acres)
B-2
Appendix B
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; Development Document - Proposed Western Alkaline Coal Mining Subcategory
The only sediment control design requirements for small disturbed area (less than 30
acres) are:
1. Sediment trapping structures (e.g., toe ditches, rock check dams) should be
designed to pass or detain runoff from storms of recurrence intervals determined
by their expected lifetimes (see Appendix 1). A generic design may be
acceptable where many similar small areas will be controlled by similar
structures as long as they will withstand the design precipitation event.
2. Rocks used to construct check dams should be angular and have an appropriate
size distribution so that the design peak flow cannot entrain them or else be
enclosed in a staked wire mesh structure.
3. Toe ditches should be graded to a zero slope, where practical. Otherwise, toe
ditches should be gently graded to a stabilized outlet that has a check dam of
porous rock, staked hay bales, or a fabric sediment fence to retain sediment.
4. Detention basins will be considered alternative sediment control only when their
capacity is less than 0.5 acre-foot.
5. The operator need only report the ASCM design and its justification with a
planview location and a general description of the type structure to the LQD.
Proposals of this size should outline the inspection and maintenance programs
the operator will use to regularly evaluate the stability and effectiveness of each
ASCM.
B. Designing ASCM's for Large Areas (30 acres and larger)
1. The design of ASCM's for large areas should be based on predicted sediment
loads or yields from the particular area of disturbance. The operator should
compare predicted or measured native sediment yields to those predicted for the
disturbed area.
2. A state-of-the-art computer watershed model should be used as an ASCM design
tool. The LQD will work with the operator to determine which model(s) can be
considered state-of-the-art for the particular application. Section VII of this
guideline includes specific model information that should be submitted.
C. Implementation Priorities for Various ASCM's
The following lists prioritize the most desirable ASCM's for each particular disturbed
area:
1. Topsoil Stripping Areas
a.
b.
c.
Divert undisturbed water around the stripped area into an approved
diversion channel.
Divert drainage from the stripped area into the pit.
Divert drainage from the stripped area away from the pit through an
Appendix B
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„ Development Document - Proposed Western Alkaline Coal Mining Subcategory
ASCM:
L
2.
3.
Place native vegetation buffer strips or filter cloth between the
disturbance and the channel.
Place sediment trapping structures in channel (porous rock
check dams, staked straw bales).
Place sediment trapping structures below the channel grade.
Overburden/Topsoil Stockpiles
a. Utilize a flat construction profile.
b. Locate stockpiles away from drainageways.
c. Use contour plowing, seeding and mulch on stockpiles.
d. Establish a good vegetative cover.
e. Grade contour ditch outlets to stabilized drainageways.
f. Grade toe ditches to sediment trapping structure that retains minimum
amount of water.
g. Grade toe ditches to zero grade and less than 0.5 acre-foot capacity.
Postmining Surfaces
a. Stable landform design
Geomorphic approaches to stable landform design are highly
recommended to minimize sediment yield. For example, drainage
density and channel and hillslope profile shapes can be varied and lose
lengths reduced to minimize sediment yield.
Short-term slope erosion controls
1. Regraded topsoil surfaces should be pitted with a large disc,
chisel plow or ripper working along the contour to increase
infiltration and detain runoff
1111 •' ""• ' '' ' i
2. Bare rounded surfaces should be mulched and vegetated rapidly.
It is highly recommended that mulch be anchored in the topsoil
and that vegetation be planted immediately after surface grading.
Cover crops provide a standing mulch that can be mowed prior
to subsequent plantings.
i
In-channel sediment retention measures
„ ,| , „
Vegetation is often sufficient to stabilize stream channels. A rock check
dam should be placed in channel reaches that produce excessive
sediment from their bed and banks. Accumulated sediment should be
regularly removed from rock check dams. Check dams should be used
as a final resort in permanently reclaimed stream channels.
B-4
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
D. Location of Sedimentation Ponds
Sedimentation ponds must be used to control runoff from facilities areas, coal stockpiles
and pit drainage. Sediment ponds may also be necessary when maintenance of ASCM's
is a chronic unresolved problem.
V. Construction and Maintenance of ASCM's
A. Construction of ASCM's
Each type of ASCM has construction and maintenance guidelines that are specified in
most handbooks on sediment control (see list of references, Appendix 2). Some basic
guidelines include:
1. Mulch must be anchored to prevent it from being washed or blown off the slope.
2. Rocks used in porous rock check dams should be the appropriate size, angularity,
and density to prevent flows from transporting them or else they should be
contained in anchored wire mesh.
3. Contour ditches should be constructed with a stabilized outlet and berms that are
well compacted and vegetated.
4. Concentrating flow in a diversion ditch can result in severe erosion by gullying if
the outlet is not adequately constructed and stabilized.
5. Baled hay check dams should be staked into the bed and banks of channels.
Flow should pass over the low point of the channel. If hay bales are placed level
across the channel, they should be staggered so that water will not pond behind
them and be deflected into the banks.
B. Maintenance of ASCM's
The operator should report, repair and log any significant damage to an ASCM as soon
as possible after the damage occurs. The operator should inspect the ASCM at the
beginning and at the end of each runoff season, and after each runoff event. An
inspection and maintenance log should be kept to document the condition of each ASCM
at the time of each inspection. The log should describe any damage, the required
maintenance, and the date repairs were made.
VI. Performance of ASCM's
A. Monitoring Ephemeral Tributary (Class IV) Streams
Where the receiving water is an ephemeral (Class IV) stream, the water quality standard
set by WDEQ/WQD Rules and Regulations, Chapter 1, Section 15, is as follows:
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
"...substances...influenced by the activities of man that will settle to form sludge, bank or
bottom deposits shall not be present in quantities which could result in significant
aesthetic degradation,... or adversely affect public water supplies, agricultural or
industrial water use, plant life or wildlife, etc."
1. Small ephemeral receiving streams
i .|| . .; - r . ' ' ! ' ! i':'
Small ephemeral receiving streams (drainage areas less than 0.5 square miles)
that are receiving waters for ASCM's should be visually inspected after each
runoff event.
a.
b.
Channels and hillslopes should be inspected for signs of rill and gully
erosion. The volume and location of any recently accumulated
sediments should be recorded.
; . '' ' !, ' '!'.••
Repeat photographs should be taken at least annually and after large
runoff events at several permanent locations along the receiving stream
to supplement the written record of observations.
2. Large ephemeral receiving streams
i;; ' ' '.. i '• .i
In addition to the requirements for visually monitoring small ephemeral
receiving streams, monitoring of large ephemeral receiving streams (drainage
areas greater than 0.5 square mile) should include one, or both, of the following:
a.
b.
Repeat surveys of representative permanently benchmarked stream
channel cross sections located within the disturbed reach of the channel
and continuing into the receiving stream channel.
j
Upstream and downstream sediment yield monitoring stations that
follow the plan set forth for Class I, n, and HI streams below.
B-6
B. Monitoring Class I, n, and in streams
Any class I, n or HI receiving stream should be monitored upstream and downstream of
the disturbed area so that any potential increase in sediment load related to mining
disturbance can be detected.
', I 'I'! " . „' "' • " ! ' , ' 'I
1 • The methods of data collection and the analytical basis for determining whether
or not degradation has occurred should be outlined in detail in the ASCM
proposal.
i. Continuous flow recorders and automatic sediment samplers should be installed
at permanent upstream and downstream station locations.
3. Automatic sediment samplers should begin sampling at the onset of each runoff
event and continue at 5 to 10 minute intervals throughout each runoff event.
Other sampling intervals or methods will be considered according to their ability
to verify sediment yields.
i Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
4. The applicant should submit a monitoring station maintenance plan. Data from
monitoring stations should be retrieved within 24 hours of each runoff event.
Faulty equipment should be immediately repaired or replaced. Monitoring
stations should be inspected by the operator after every runoff event, and a log of
monitoring and maintenance activities should be kept for LQD review. The
LQD will be looking for a long-term record of maintenance as well as a
company's efforts to correct problems in a timely fashion.
VII. Contents of an ASCM Proposal
The proposal for implementation of an ASCM for areas greater than 30 acres should include the
following items:
A. A general description of the area to be controlled by ASCM's and the types and duration
of expected disturbance include the distance to and type of nearest receiving stream
and/or Class I, n, or HI stream.
B. Description of the ASCM Design Procedure
1. List and justify values chosen for the watershed (or subwatershed) variables and
model parameters (e.g., soils, sediment grain size distribution, slopes, etc.).
2. Where applicable, submit data used to calibrate model and the calibration results
(e.g., design hydrographs, hyetographs, curve numbers, etc.).
3. Explain the choice of ASCM's.
4. Submit and justify the design storm recurrence interval and duration, runoff
volume, and peak discharge.
5. Submit sample calculations and/or computer model output.
C. Provide a map of ASCM's on a mining sequence topographic map or overlay. Each
ASCM should be referenced in the descriptive text and design information, and dates of
construction or implementation of each ASCM should be given. This map should be
updated in each Annual Report if modifications are made.
D. Provide specifications for each ASCM and a schematic diagram of each typical structure.
Er For reclaimed areas:
1. Refer to drainage basin and channel designs in reclamation plan:
a. Longitudinal profiles of reclaimed channels.
b. Typical reclaimed channel cross sections.
c. Reclaimed area contour map with 10' or less contour interval.
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
i
d. Justification of drainage basin design.
e. Reclaimed basin characteristics such as: relief ratio, drainage area,
topsoil and spoil particle sizes, average channel slope. Include
discussion of how reclaimed basins, slopes and channels are designed to
minimize additional sediment yield to downstream areas.
2. Surface treatments (mulch, contour ripping).
3. Channel protection measures, if any.
F. Maintenance and inspection plan.
G. Monitoring plan and description of degradation analysis.
H. If any impounding structure is designed to retain more than 2.0 ac-ft of water, a WQD
permit must be obtained.
I. ASCM's designed to control large disturbed watersheds (excluding isolated small areas)
may need to be permitted through the State Engineer's Office (Form SW-1, Application,
to Appropriate Surface Water). The State Engineer's Office should be contacted directly
to determine whether or not such a permit is required.
B-8
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
APPENDIX 1
Design Events for Temporary Structures
Exceedance of the design runoff is likely to result in destruction of in-channel ASCM's and in the
remobilization of any stored sediment. Therefore, temporary structures should be designed for an event
with some reasonably small probability of occurrence over the structure's lifetime.
Example:
The highest acceptable risk of structure failure during that structure's lifetime is 20%.
Table 1 shows event return periods for which the risk of failure (at least once) over a
given number of years will be no greater than 20%. The return periods in Table 1 were
calculated from the following equation:
P = 1 - (1-1/t) n
where P is the probability that an event of return period t will be equaled or exceeded at
least once during the course of n years (Linsley, Kohler and Paulhus, 1982).
Table 1 - Design Event Return Periods
Expected Lifetime of Structure (yrs)
Design Event Return Period (yrs)
2
10
5
25
7
33
10
50
Over any two-year period, a 10-year event has a 20% chance of being equaled or exceeded
at least once. Therefore, based on the criterion of 20% acceptable risk of failure, the
appropriate design storm for a structure intended to function for two years is the 10-year
peak runoff, or predicted peak runoff from the 10-year rainfall. For structure lifetimes
outside the range of those in Table 1, appropriate design storm return periods should be
calculated in the same manner from the equation given above.
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
APPENDIX 2
References
»:, i , i 'I'"
,i, • !' . . „ '• ' . J "b,
Barfield, B.J., R.C. Warner and C.T. Haan (1985). Applied Hydrology and Sedimentology For Disturbed
Areas. Oklahoma Technical Press, Stillwater, Oklahoma, 603 pp.
Dollhopf, D.J. et al (1985). Effects of Surface Manipulation on Mined Land Reclamation. Montana Ag.
Expt. Sta. Spec. Rpt 18
'- ... j * ' j '.•
Erosion and Sediment Control: Surface Mining in the Eastern U.S. EPA Technology Transfer Seminar
Public, EPA-625/3-76-006. USDA Soil Conservation Service. Nation Engineering Handbook.
Gray, D.H. & Leiser A.T. (1982). Biotechnical Slope Protection & Erosion Control. Van Nostrand
Reinhold Co., NY
Gregory, D.I., S.A. Schumm, & C.C. Watson (1985). Determination of Drainage Density for Surface Mine
Reclamation in the Western U.S. Water Eng. Tech, Ive., Rpt. prepared for OSM, Denver
Grim, B.C. & Hill, R.D. (1974) Environmental Protection - Surface Mining of Coal. EPA-670/2-74-093
(EOA, Cincinnati)
Guidelines for Erosion and Sediment Control Planning and Implementation (1972). EPA Protection
Technology Services, EPA-R2-72-015, EPA Office of Research & Monitoring, Washington, D.C.
Hittman, Assoc. & Natural Resources Consultants (1981). Erosion & Sediment Control Measures for Coal
Mines. H-C1022/001-81-1008P. Report prepared for OSM, Washington, D.C.
, V ' , l , , .I,,
Linsley, R. K., M. A. Kohler, and J. L. H. Paulhus (1982). Hydrology for Engineers, McGraw-Hill Book
Co., New York, New York.
Mining & Reclamation Council of America (1985). Handbook of Alternative Sediment Control
Methodologies for Mined Lands. Report prepared for OSM, Washington, D.C. under contract
H5130424 by Hess & Fish Engineers.
Morris, R.N., Basi, F.E. & Doehring, D.O. (1980). ALiterature Review: Mined-Land Sediment Control and
the Dryland Fluvial System. Report Prepared for Pittsburg & Midway Coal Mining Company by
Research Institute of Colorado.
Simons, Li & Assoc. (1982). Engineering Analysis of Fluvial Systems. SLA, Ft. Collins, Co.
Simons, Li & Assoc. (1983). Design of Sediment Control Measures for Small Areas in Surface Mining.
Report Prepared for OSM.
USDA-SCS Engineering Field Manual for Conservation Practices S. Doc: A57.6/2: En 3/3/984
B-10
Appendix B
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix C: 19 NMAC 8.2, Subpart 20, Section 2009
Appendix C
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix C
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Introduction
New Mexico's Mining and Minerals Division (MMD) enforces the state's federally
approved SMCRA primacy program. BMP regulations for coal mining and reclamation
operations in New Mexico may be found under 19 NMAC 8.2 Subpart 20 Section 2009 which
addresses general requirements for minimizing changes to the prevailing hydrologic balance in
both the permit and adjacent areas. Section 2009 of Subpart 20 is presented below:
19 NMAC 8.2.20.2009 HYDROLOGIC BALANCE: GENERAL REQUIREMENTS
2009.A Surface coal mining operations shall be planned and conducted to minimize changes to the
prevailing hydrologic balance in both the permit and adjacent areas and prevent material damage outside
of the permit area in order to prevent adverse changes in that balance that could result from those
operations. [11-29-97]
2009.B Changes in water quality and quantity, in depth to ground water, and in the location of surface
water drainage channels shall be minimized so that the approved postmining land use of the permit area
is not adversely affected. [11-29-97]
2009.C In no case shall Federal and State water quality statutes, regulations, standards, or effluent
limitations be violated. [11-29-97]
2009.D Operations shall be conducted to minimize water pollution and, where necessary, sediment ponds
or other treatment facilities shall be used to control water pollution.
(1) Each person who conducts surface coal mining operations shall emphasize mining and
reclamation practices that prevent or minimize water pollution. Methods listed in
paragraph 2009.D(2) and (3) shall be capable of containing or treating all surface flow
from the disturbed areas and shall be used in preference to the use of sediment ponds or
water treatment facilities.
(2) Acceptable practices to control sediment and minimize water pollution include, but are
not limited to:
(i) stabilizing disturbed areas through land shaping, berming, contour furrowing
or regrading to final contour;
(ii) diverting runoff;
(iii) achieving quickly germinating and growing stands of temporary vegetation;
(iv) regulating channel velocity of water;
(v) lining drainage channels with rock or revegetation;
Appendix C
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
(vi) mulching;
(vii) selectively placing and sealing acid-forming and toxic-forming materials;
' ' M ;"; •'••* ' and , i
(viii) selectively placing waste materials in backfill areas.
(3) In addition, unless demonstrated to the Director otherwise, all acceptable practices for
controlling and minimizing water pollution at underground mines shall include, but not
be limited to:
(i) designing mines to prevent gravity drainage of acid waters;
(ii) sealing all underground mine openings;
(iii) controlling subsidence; and
(iv) preventing acid mine drainage.
(4) If the practices listed in paragraph 2009 .D(2) are not adequate to meet the requirements
of paragraph 2009.D(1), the person who conducts surface coal mining operations shall
comply with the requirements of Section 2010, unless the Director issues a waiver under
paragraph 2009.E. [11-29-97]
2009.E The Director may waive the requirements of this Section for regraded areas if the operator can
demonstrate to the Director that the runoff from the regraded area is as good as or better quality than the
waters entering the permit area and erosion from the regraded area has been controlled to the satisfaction
of the Director.
(1) To provide for baseline data for waters entering the permit area, the operator shall
operate and maintain monitoring on all drainages leading into the permit area, in a
fitanner approved by the Director, in order to obtain and evaluate occurrences and
changes in water quality and quantity during the life of mining operations.
(2) In order to ensure that runoff from the regraded area is in no way a hazard to the
environment of the adjacent areas, the waters draining off of the regraded area shall not:
(i) exceed the values of Total Suspended Solids, Iron, Manganese, pH and those
parameters listed in paragraph 2009.E(3)(I) from the baseline analyses from the
water entering the permit area;
•t ' •'' • , ;•, •".. ft ' : '!•' i1 : *'• '/ i • i ; ' ' I II
(ii) create an increase in sediment load into the receiving streams;
(iii) create any environmental harm or threat to public health and safety; and
" < ? (iv) degrade, pollute or otherwise diminish the characteristics of existing streams
f, 'i and drainages so as to cause imminent environmental harm to fish and wildlife
habitats.
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\ Development Document - Proposed Western Alkaline Coal Mining Subcategory
(3) Baseline data shall be collected from waters in drainages entering the permit area and
runoff from regraded areas shall be collected during any precipitation event that
produces such runoff. The operator shall demonstrate to the Director that the runoff from
the regraded area has as good as or better chemical quality than the baseline analyses
from waters entering the permit area.
(i) In addition to paragraph 2009.E(2)(I), chemical analysis of the runoff from
the regraded area and baseline data from waters entering the permit area shall
include, but not limited to, the following parameters:
Arsenic (As)
Boron (B)
Calcium (Ca)
Chloride
Cadmium (Cd)
Fluoride
Lead (Pb)
Magnesium (Mg)
Radium Ra228
Phosphorus (P)
Potassium (K)
Selenium (Se)
Sodium (Na)
Uranium (U)
Vanadium (V)
Radioactivity
Radium Ra226
Carbonate (COS)
Bicarbonate (HCO3)
Nitrate (NO3)
Sulfate (SO4)
Total Dissolved
Solids (TDS)
Sodium Adsorption
Ratio (SAR)
(ii) The Director may require additional tests and analyses as he deems
necessary.
(iii) If the operator can demonstrate that the analysis of any particular parameter
are of little or not significance in the permit or adjacent areas, then such
parameter(s) may be waived upon approval by the director.
Appendix C
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
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Appendix C
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Development Document - Proposed Western Alkaline Coal Mining Subcateeory
APPENDIX D: Mine Modeling and Performance Analysis -
Model Input and Output Data
Appendix D
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"I!!IF I.;1 "li,1!1,1! II*
JlliPV
I'l"1!,'1!'1 •!! ""I11: '"fi"
Development Document - Proposed Western Alkaline Coal Mining Subcategory
J'V *
Appendix D
i ' !'!.< JiLljinlilufllliljl ' nIPiIliiillllld; < JiLi,
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Development Document - Proposed Western Alkaline Coal Mining Subcategory
Introduction
This Appendix contains model input and output data for the mine modeling performed for
NMA using RUSLE version 1.06 and SEDCAD 4.0. This study was submitted to EPA as
"DRAFT - Western Alkaline Mining Subcategory Mine Modeling and Performance-Cost-Benefit
Analysis" in support of the Western Alkaline Mining Subcategory proposal (WCMWG, 1999c).
These data and information support the sedimentology and hydrology modeling results presented
in Section 6, Case Study 1 of this document. The supporting input and output data for the
RUSLE modeling is presented first (Tables D-l through D-6) followed by the SEDCAD output
information (Exhibits D-l through D-3)..
RUSLE Version 1.06 Modeling
Soil loss estimates from a representative model mine were developed using RUSLE
version 1.06. The backup input and output data are summarized in table form here as:
« Table D-1: RUSLE Input Variables For Premining Subwatersheds
• Table D-2: Premining RUSLE Model Output
* Table D-3: RUSLE Input Variables For Reclaimed Subwatersheds
• Table D-4: Input And Output Variables For Reclaimed Areas
• Table D-5: Postmining Reclamation RUSLE Erosion Model Output
• Table D-6: Weighted Average Soil Loss Estimates For Disturbed and Reclaimed
Subwatersheds (RUSLE)
SEDCAD Version 4.0 Modeling
Hydrology and sedimentology data were generated for the model mine under three
scenarios: undisturbed (premining) conditions; reclamation under current 40 CFR Part 434
guidelines; and reclamation with alternative BMPs. The supporting reports as produced by
SEDCAD for the three scenarios are presented in this Appendix:
• Exhibit D-l: Premining Undisturbed Conditions
• Exhibit D-2: Postmining Reclaimed Conditions, Existing Guidelines
* Exhibit D-3: Postmining Reclaimed Conditions, Proposed Subcategory
Appendix D
D-l
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
TABLE D-l: RUSLE Input Variables For Premining Subwatersheds
Reclaimed
Watershed
SW3A
SW3B
SW7
SW9
SW10
SW11
SW13
SW14
SW15
SW17
Subtotal
SW1A
SW1B
SW2
SW4
SW5
SW6
SW8
SW12
SW16
SW18
Subtotal
Total
Reclaimed
Watershed
Area
(acres)
31.2
15.5
25.9
290.0
14.0
15.0
105.3
9.3
30.520
78.5
616.7
44.6
140.1
104.1
75.3
5.5
26.1
23.8
72.6
55.9
23.3
571.3
1188.0
R
30
30
30
30
30
30
30
30
30
30
K
0.29
0.24
0.32
0.24
0.32
0.35
0.27
0.32
0.32
0.36
L
700
435
500
425
500
275
390
300
160
375
S
3.5
5.0
10.0
7.0
6.7
7.1
6.7
5.4
12.5
7.6
C
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.45
P
1.00
1.00
0.47
1.00
1.00
1.00
1.00
1.00
1.00
1.00
Composite
Curve
Number
81
79
88
77
90
91
81
88
88
92
Hydrologic
Condition
C
B
D
B
D
D
C
D
D
D
Acres for subwatershed that will contain 381.8 acres of mining
disturbance.
30
30
30
30
30
30
30
30
30
30
0.37
0.37
0.37
0.35
0.32
0.37
0.37
0.37
0.33
0.32
650
800
850
350
190
250
315
360
440
375
4.5
3.0
2.5
7.0
10.0
8.0
6.3
8.3
8.2
7.0
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.45
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
, 93
93
93
92
88
93
93
93
92
88
D
D
D
D
D
D
D
D
D
D
acres for subwatershed area that will not be disturbed by mining.
acres
D-2
Appendix D
,,1 iSi...
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
TABLE D-l: RUSLE Input Variables For Premining Sub watersheds (Continued)
Reclaimed
Watershed
SW3A
SW3B
SW7
SW9
SW10
SW11
SW13
SW14
SW15
SW17
SW1A
SW1B
SW2
SW4
SW5
SW6
SW8
SW12
SW16
SW18
Soil Type
Loamy Sand
Loamy Sand
Sandy Clay Loam
Loamy Sand
Sandy Clay Loam
Sandy Clay Loam
Loamy Sand
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Sandy Clay Loam
Surface Condition
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Undisturbed
Number of
Years to*
.Consolidate
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
f/?
General Land ,„
Use
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
Appendix. D
D-3
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
TABLE D-2: Premining RUSLE Model Output
mm ••- ? -T"
Exit Help Screen
; < RUSLE 1.06 >
Soil Loss and Sediment Vield Computation Worksheet
| filename
PRE-SHlfl
PRE-SH1B
PRE-SH2
PRE-SH3fl
PRE-SH3B
PRE-SW4
PRE-SH5
PRE-SM6
PRE-SW7
PRE-SH8
NOTES:—
R x K x LS x
x [P
SDR] =
•*$E0H_ "80.37 0.68 »$0.45 "$1.00 0
"$30 "0.37 0.42 *$0.45 "$1.00 0
-$30 "0.37 0.37 *$0.45 "$1.00 0
-$30 "0.29 0.55 «$0.45 "$1.00 0
"$30 "0.24 1.12 *$0.45 "$1.00 0
-$30 "0.35 1.02 »$0.45 «$1.00 0
-$30 «0.32 1.43 *$0.45 *$1.00 0
«$30 "0.37 1.12 *$0.45 "$1.00 0
"$30 "0.32 1.74 «$0.45 *$1.00 0
"$30 "0.37 0.90 "$0.45 "$1.00 0
value entered directly or file was saved elsewhere—
factor value is not based upon current factor inputs
the field slope for this factor is not current
< F4 Calls Factor, Esc Returns to RUSLE Main Menu >
Tab Esc Fl F2 F4 F9
FUNC esc help clr call info
;~ MS-DOS Prompt , -...--;
i&iriiiai-iiMiiflnircaiiiinii
mm
j|3"5Il:|S
File
iin
Exit
Ml
AT
Help
-
Screen
'•--•••!• ;.• T,., .:— "feft-isisijsl
< RUSLE 1.06 >
Soil Loss and Sediment Yield Computation Worksheet
{ filename
PRE-SH9
PRE-SW18
PRE-SW11
PRE-SH12
PRE-SW13
PRE-SU14
PRE-SM15
PRE-SW16
PRE-SW17
PRE-SW18
NOTES:—
R x K x LS x
x [P
*0.24
«0.32
»0.35
-0.37
«0.27
-0.32
*0.32
-0.33
-0.36
.
«$0.45
"$0.45
-$0.45
«$0.45
"$0.45
«$0.45
"$0,45
"$0.45
*$0.45
-$1.00
»$1.00
«$1J
$1.00
»$1.00
"$1.00
"$1.00
«$1.00
»$1.00
*$1.00
T w vr . ^^*_ JW*^'"* *f^u/«»«'V> f,l_ . ^^ U *J —
value entered directly or file was saved elsewhere-
the field slope for this factor is not current
!~—— -< F4 Calls Hactor, Esc Returns to RUSLE Main Henu >-
FUNC esc help clr call info
D-4
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
TABLE D-3: RUSLE Input Variables For Disturbed/Reclaimed Subwatersheds
Reclaimed
Watershed
SW3A
SW3B
SW3C
SW3D
SW3E
SW3F
SW3G
SW3H
SW3I
SW7A
SW7B
SW9A
SW9B
SW9C
SW9D
SW9E
SW10
SW11A
SW11B
SW13A
SW13B
SW13C
SW13D
SW13E
SW13F
SW13G
SW13H
SW13I
SW13J
SW14A
SW14B
SW15A
SW15B
SW17A
SW17B
SW17C
SW17D
SW17E
Total
Reclaimed
Watershed
Area
(acres)'
20.295
14.907
8.414
11.884
5.500
6.443
14.513
70.798
8.314
9.965
11.735
40.766
7.113
29.932
9.575
30.520
8.058
15.142
13.858
22.100
7.328
13.158
8.547
13.831
9.556
16.221
13.248
12.053
35.792
5.974
4.650
15.352
16.414
3.038
12.123
8.741
10.010
50.821
616.7
R
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30-
30
30
30
'«
0.29
0.25
0.24
0.15
0.29
0.24
0.24
0.24
0.24
0.24
0.32
0.26
6.3
71.8
36.4
94.6
35.5
59.1
44.3
57.5
22.0
12.8
7.5
13.4
29.6
50.3
60.9
35.0
78.7
16.1
15.3
64.5
72.2
11.5
14.5
8.3
44.0
264.3
/
L
650
750
250
500
450
400
475
550
250
500
125
340
250
375
400
475
225
500
275
500
100
450
250
250
275
375
L385
375
525
300
300
375
600
100
450
450
475
375
S
7.0
3.5
11.0
6.0
6.0
2.6
5.0
2.9
8.2
6.4
8.0
7.3
6.0
5.5
6.4
4.5
7.5
6.0
7.1
5.0
6.4
5.0
6.0
5.0
9.0
6.6
8.0
5.3
3.8
5.4
5.4
7.2
6.4
6.5
6.0
6.0
7.0
7.0
C
0.45
0.45
0.45
0.31
0.05
0.45
0.63
0.49
0.45
0.45
0.45
0.45
0.31
0.48
0.45
0.51
0.45
0.45
0.45
0.45
0.45
0.31
0.31
0.30
0.45
0.55
0.63
0.49
0.47
0.45
0.45
0.45
0.45
0.45
0.31
0.18
0.63
0.45
:P
1.00
1.00
1.00
0.47
0.44
1.00
0.45
0.63
1.00
0.69
1.00
1.00
0.47
0.51
0.69
0.72
1.00
0.69
1.00
1.00
1.00
0.47
0.47
0.45
0.46
0.47
0.47
0.63
0.67
0.69
1.00
0.69
1.00
1.00
0.47
0.45
0.47
1.00
Composite ^
Curve
Number "
80
79
79
65
74
79
74
74
79
74
88
80
65
74
74
74
92
74
91
79
81
65
65
74
74
74
74
74
74
74
88
74
88
93
74
74
74
92
Hydrologic
Condition
B
B
B
A
B
B
B
B
B
B
D
C
A
B
B
B
D
B
D
B
C
A
A
- B
B
B
B
B
B
B
D
B
D
D
B
B
B
D
Appendix D
D-5
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
TABLE D-3: RUSLE Input Variables For Disturbed/Reclaimed Subwatersheds
(Continued)
i'
•iii'iji
'"I1 ,1"
'il
1
,
"'III1
"ill
!!,,:
,|M
i
Reclaimed
Watershed
SW3A
SW3B
SW3C
SW3D
SW3E
SW3F
SW3G
SW3H
SW3I
SW7A
SW7B
SW9A
SW9B
SW9C
SW9D
SW9E
SW10
SW11A
SW11B
SW13A
SW13B
SW13C
SW13D
SW13E
SW13F
SW13G
SW13H
SW13I
SW13J
SW14A
SW14B
SW15A
SW15B
SW17A
SW17B
SW17C
SW17D
SW17E
Soil Type
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Sandy Clay Loam
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Sandy Clay Loam
Loamy Sand
Sandy Clay Loam
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Loamy Sand
Sandy Clay Loam
Loamy Sand
Sandy Clay Loam
Sandy Clay Loam
Loamy Sand
Loamy Sand
Loamy Sand
Sandy Clay Loam
Surface Comdition
Undisturbed
Undisturbed
Undisturbed
Spoil, backfilled & graded
Topdressed, straw mulched & seeded
Undisturbed
Reveg. 1-3 Years
Reveg. 4-8 years/some reveg. 1-3 years
Undisturbed
Reveg. 4-8 years
Undisturbed
Undisturbed
Spoil, backfilled & graded
Reveg. 1-3 Years/some topdressed area
Reveg. 4-8 years
Reveg. 4-8 years/some 1-3 years/some undisturbed
Undisturbed
Reveg. 4-8 years
Undisturbed
Undisturbed
Undisturbed
Spoil, backfilled & graded
Spoil, backfilled & graded
Topdressed/some reveg. 1-3 years
Reveg. 1-3 Years/some topdressed area
Reveg. 1-3 Years/some topdressed area
Reveg. 1-3 Years/some reveg. 4-8 years
Reveg. 4-8 Years/some reveg. 1-3 years
Reveg. 4-8 Years/some reveg. 1-3 years
Reveg. 4-8 Years
Undisturbed
Reveg. 4-8 Years/some reveg. 1-3 years
Undisturbed
Undisturbed
Spoil, backfilled & graded
Topdressed/some reveg. 1-3 years
Reveg. 1-3 years/some topdressed/some spoil
Undisturbed/some reclaimed
Number of
Years to
Consolidate
7
7
7
10
10
7
10
10
7
10
7
7
10
10
10
10
7
10
7
7
7
10
' 10
10
10
10
10
10
10
10
7
10
7
7
10
10
10
7
General
Land Use
6
6
6
10
8
6
8
8
6
8
6
6
10
8
8
8
6
8
6
6
6
10
10
8
8
8
8
8
8
8
6
8
6
6
10
8
8
6
ii! ;' -; i, -""IT, ";.::j| ' ' •'•' >'?'••' ,' : ' •' , . •.,:!. ' ' „. • • •• • ' ' ' : "it. '!;. • • i1:!:11 , • :,; '• ' • . ." !>'/
D-6
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcat,
TABLE D-4: RUSLE Model Input And Output Variables For Reclaimed Areas
'egory
fg MS-DOS Prompt
ji nFM
OKSSXft -'I 1
•Help Screen
< RUSLE 1.06 >•
filename
SPOIL
~3Q
*3D
*30
*30
0,
o •;
0
0
0
0
0
0
0
.0
0
0
0
0
D
.15
,24
.24
.24
SDR] =
U.47 =
0,44 -
0,47 =
0.69 =
NOTES
entered directly or file was saved else*
Tab Esc Fl
iFWJCi esc he
Area Filename
SPOIL
TOPDRESS
REVEG1-3
REVEG1-4
call info
Description
Mine spoil backfilled and graded, consisting of loamy sand overburden- CN = 65- k = 0 15-
hydrologic condition = A; 25% gravel, 10% cobble, 5% rock fragments; slow h'ydrolo-ic
response time. J &
Area topdressed, consisting of loamy sand topsoil; roughened with contour furrows- straw
mulched (2 tons/acre); recently seeded with no growth started; CN = 74- k = 0 24-
hydrologic condition = B; medium hydrologic response time. ' '
Area originally prepared the same as previous topdressed area; 1-3 years of vegetative
growth; surface roughening slightly decreased from erosion, sedimentation and
consolidation; CN = 74, k = 0.24; hydrologic condition = B; medium hydrologic response
Area originally prepared the same as previous topdressed area; 4-8 years of vegetative
growth typically more dense than area with 1-3 years of vegetative growth; surface
roughening continuing to decrease from erosion, sedimentation, and consolidation; CN =
74, k = 0.24; hydrologic condition = B; medium hydrologic response time.
Appendix D
D-7
-------
it Document - Proposed Western Alkaline Coalmining Subcategory
TABLE D-5: Postmining Reclamation RUSLE Erosion Model Output
Help
—< RUSLE
(tent Vie
tlue entered dir-
1.84 "0.45
1.98 0.31
1.64 m.05
0.37 *0.45
__< p4 calls Factor, Esc Returns to RUSLE Main Menu >—
ESC Fl F2 F4 F9
C!E call info
MS-DOS Prompt
filename
PSTSW7B
PSTSEF9A
PSTSW9B
PSTSWPD
PSTS6T11A
PSTSW11B
joss and.
Help Screen
< RUSLE 1.06 > •
idiment Yield Computation Wocksheei
*0.45
*0.45
0.31
*0.48
0.45
*0.51
*0.45
0.45
*0.45
1.00
1.00
0.47
*0.51
-0.69
•0.72
1.00
0.69
1.00
entered directly or file v,ras saved e
0.69
1.00
1.00
0.47
*0.51
*0.69
*0.72
1,00
0.69
1.00
slsewhe
=
•
•
•
m
=
B
=
=
=
re-
Tab Esc FJ.
c F4 Calls Factor, Esc Returns to RUSLB Main Menu
; F4 F9
'.c call info
ill' I!!1" ! ' ":llilB!i
D-8
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
PBTS8tl3B
PJ3TSW13F
PBTSOT.3G
PBTSW13H.
P&TSW13J
'• - Help . 'screen
< RUSLE 1.06 >—
Soil Loss and Sediment Yield Comoutu
*0.45
0.31
0.31
*0.30
*0.45
*0.55
0.63
Worksheet.
1.00
1.00
0.47
0.47
*0.45
*0.46
*0.47
0.47
ralue -.entered directly or
Tab! Esc Fl
UNij: esc help clc call" info
Esc Retucns .toJv|RXJSLB>Main -Menu >
MStDUS Piompt
PS|TS®14B
psfrswnc
Exit : Help iscreeq
^ : •"-'—— < RUSLE 1.06 > \
Soil Loss and Sediment Yield Computation Worksheet
I
;, . ]
R K "K., :-: LS K C x [d -- ' j SDR] -
DJ69 0.69 -
•1JOO 1.00 =-
- O.J69 0.69 =
l.iOO 1.00 =
1JOO 1,00 =
O.J47 0.47 =
*OJ45 *0.4S =
0,147 0.^7
1.JOO 1.00 =
0 ! 0
" ~;aKred elsewhere-
value entered directly or
1 ^III. .'CaljL?factor,-Esc':-Itetui:n^.":tQ':-fe;USLB Main Menu
i"ab Esc Fl F2 F4 F9 ' ' ,
fVNC esc help clE._call info , ),
Appendix D
D-9
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
TABLE D-6: Weighted Average Soil Loss Estimates For Undisturbed And Reclaimed
Watersheds (RUSLE)
UJNDISTUKJ5ED WAlEKS>JHUbD |
Undisturbed
Watershed
SW3A
SW3B
SW7
SW9
SW10
SW11
SW13
SW14
SW15
SW17
Totals
Undisturbed
Watershed
Area
(acres)
31.2
15.5
25.9
290.0
14.0
15.0
105.3
9.3
32.0
78.5
616.7
Average
Annual
Soil Loss
(tons/acre)
2.2
3.6
7.5
4.5
4.5
4.7
4.0
3.3
8.2
5.6
Average
Annual
Soil Loss
(tons)
68.7
55.8
194.2
1305.0
63.1
70.6
421.2
30.7
262.0
439.6
2911.0
Weighted Average Soil Loss = 4.7 tons/acre/yr.
KJKUJL/AJJVIJKU WAlJKKISW-lill
Reclaimed
Watershed
SW3A
SW3B
SW3C
SW3D
SW3E
SW3F
SW3G
SW3H
SW3I
SW7A
SW7B
SW9A
SW9B
SW9C
SW9D
SW9E
SW10
SW11A
SW11B
SW13A
SW13B
SW13C
SW13D
SW13E
SW13F
SW13G
SW13H
SW13I
SW13J
SW14A
SW14B
SW15A
SW15B
SW17A
SW17B
SW17C
SW17D
SW17E
Reclaimed
Watershed
Area
(acres)
20.3
14.9
8.4
11.9
5.5
6.4
14.5
70.8
8.3
10.0
11.7
40.8
7.1
29.9
9.6
30.5
8.1
15.1
13.9
22.1
7.3
13.2
8.5
13.8
9.6
16.2
13.2
12.1
35.8
6.0
4.7
15.4
16.4
3.0
12.1
8.7
10.0
50.8
616.7
Average
Annual
Soil Loss
(tons/acre)
4.8
1.9
5.9
1.3
0.27
1.2
2.7
1.5
3.9
4.2
4.3
4.0
0.88
2.4
3.8
3.1
4.4
3.9
3.2
2.6
3.0
0.97
0.88
0.97
3.1
3.1
4.6
2.9
2.2
2.7
3.3
4.2
4.4
3.8
1.2
0.95
4.4
5.2
Average
Annual
Soil Loss
(tons)
97.4
28.3
49.6
15.4
1.5
7.7
39.2
106.2
32.4
41.9
50.5
163.1
6.3
71.8
36.4
94.6
35.5
59.1
44.3
57.5
22.0
12.8
7.5
13.4
29.6
50.3
60.9
35.0
78.7
16.1
15.3
64.5
72.2
11.5
14.5
8.3
44.0
264.3
1859.8
Weighted Average Soil Loss = 3.0 tons/acre/yr.
D-10
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix D: Exhibit D-l
SEDCAD 4.0 Output
for
Premining Undisturbed Conditions
Appendix D
D-ll
-------
Development Document - Proposed Western Alkaline Coal Mining Subcateeory
General Information
Storm Information:
Storm Type: NRCSTypeH
Design Sturm:
10yr-24hr
Rainfall Depth:
1.800 inches
Particle Size Distribution:
Size (mm)
2.3000
0.1000
0.0500
0.0020
0.0010
. psdl
100.000%
83500%
77.000%
56.000%
0.000%
psd2
100.000%
30.000%
17.000%
11.000%
0.000%
D-12
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Structure Networking:
Type
Null
Null
Null
Null
Null
Null
Null
Null
Null
Stru (flows Stm
# into) #
*1 ==> #2
« ==> #3
#5 ==> #4
#4 ==> #5
#5 • ==> #6
#6 =-> #7
#7 . ==> #8
#8 • ==> #9
#9 ==> End
Musk. K „.
(hrs) Musk>x
0.050 0.429
Description
Structure #2
0.018 0.435 | Structure #3
. 0.029 0.433 ! Structure #3
0.021 0.435
0.042 0.421
Structure #4
Structure #5
0.023 0.4213 j Structure #6
0.060 0.419 | Structure #7
0.048 . 0.397
0.000 0.001)
Structure #8
Structure #9
Null
#2
Null
S3
Null
#4
Null
sfS
Huff
#6
Null
#7
Null
#8
Null
#9
Null
Structure Routing Details:
Stm
#
#1
#1
#2
Land Row Condition
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Slope {%)
1.30
1.60
VertDist.
(ft)
24.00
12.00
Horiz-Dist.
(ft)
1,847.57
751J5
Velocity
(rps)
10.25
11.37
Time (hrs)
0.050
O.O50
0.018
Appendix D
D-13
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
SOU
*2
#3
*3
#4
#5
#6
#6
#7
#7
#8
*8
Land How Condition
M inking um K:
9. Small streams flowing bankful)
Muridngum 1C
9. Small streams flowing bankfull
Muckingum 1C
9. Small streams flowing bankfull
MuridngumK:
9. Small streams flawing bankfull
HmkingumK:
9. Small streams flowing bankfull
9. Small streams flowing bankfull
Hmkingmn'IC
... .«,> vercusL. 1-iaiz.Lnsc. i
Slope (%) {ft) (ft)
1.47 17.00 1,153.01
158 14.00 887.93
1.01 14.00 1,385.68
1^7 - 11.00 866.89
0.95 18.00 1,900.33
0.53 6.00 1,139.38
-Jjr T,me(hrs)
10.92
11.30
9.04
10.13
8.75
6.53
O.O18
0.029
O.O29
0.021
O.O21
0.042
O.O42
0.023
0.023
0.060
O.O6O
o.o4a
O.048
D-14
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Structure Summary:
#1
. #2
#3
#4
#5
#6
#7
#8
#9
Immediate
Contributing
Area
(ac)
288.818
122.068
31.628
49.698
304.024
87385
114.620
87.850
102.240
Total
Contributing
Area
(ac)
288.818
410.886
442.514
492.212
796.236
883.821
998.441
1,086.291
1,188.531
Peak
Discharge
(eft)
244.26
309.65
327.01
376.42
429.48
493.76.
558.68
608.08
679.09
Total
Runoff
Volume
(ac-ft)
27.26
35.48
38.31
42.30
51.82
59.93
64.65
71.70
80.01
Sediment
(tons)
1,477.1
2,189.0
2,489.4
3,029.8
3,872.1
4,804.7
5,250.4
6,095.5
7,004.2
Peak
Sediment
Cone.
(mg/1)
86,019
99,259
99,890
110,345
120,640
126,327
144,849
154,019
155,091
Peak
SetfleaWe
Cone.
(ml/1)
15.54
' 18.12
19.13
22.47
34.36
31.92
41.43
40.49
38.22
24VW
"(ml/!)
8.32
9.61
10.46
12.02
17.72
16.88.
19.11
18.46
17.89
Appendix D
D-15
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Subwatershed Hydrology Detail:
I ,
I!!'1
Hi'1-
5 •:
Stru SWS
$ *
SI 1
2
3
2
*2 1
2
3
2
S3 1
2
2
34 1
2
2
#5 1
2
2
#6 1
2
2
#7 1
2
2
as i
2
2
#9 1
2
2
SWS Area '
(ac)
44.593
140.138
104.087"
zsasis
31.234
15.493
75341
41O.886
5.514
26.114
442L514
25.898
23300
492.212
289.995
14.029
796.236
15.023
72.562
883,821
105.300
' 9.320
gga44i
31.950
55.900
1,066.291
78.950
23.290
1,188^31
rime of
Cone
(hrs)
0.121
0.166
.0.165
0.128
0.060
0.172
0.044
0.120
0.062
O.OS2
0.245
0.055
0.076
0.282
0.056
0.043
0.135
0.221
0.128
0.126
MuskK
(his)
0.104
0.000
0.000
0.016
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
MusfcX
0.440
0.000
0.000
0.449
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
•
0.000
0.000
Curve
Number
93.000
93.000
93.000
81.000
79.000
91.500
88.000
93.000
88.000
93.000
77.100
90300
91.200
93.000
80.600
88.000
88.000
91.900
91.500
88.000
UHS
M
M
M i
M i
M 1
M
1
M
M
M
M
M
M
M
M
M
M
M
M
M
M
Peak
Dischai^e
(eft)
50.25
111.94
83.14
244.26
10.57
7.38
54.68
309.65
4.81
29.43
327.01
22.59
26.82
376.42
57.78
13.86
429.48
15.54
.51.41
49X76
56.78
8.13
558.68
18.58
39.48
608.08
57.57
13.55
679.O9
Runoff
Volume
(ac-lt)
4.209
. 13.227
9.824
27.260
1.254
0329
6.433
35.476
0.371
2.465
3&311
1.741
2.245
42.299
8.416
1.105
51.82O
1.257
6349
59.925
4.095
0.627
64.647
2.148
4.903
71.698
6.741
1.566
8O.005
Subwatershed Sedimentology Detail:
D-16
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subt
Stm SWS
# *
#1- 1
2
3
SoilK
0.370
0.370
0.370
L(ft)
650.00
600.00
850.00
S(%)
4.50
3.00
230
C
0.4500
0.4500
' 0.4500
P
1.0000
1.0000
1.0000
PS*
Sediment
(tons)
1 | 4523
1
633.3
1 391.6
2
.#2 1
2
3
0.290
0.240
0.355
700.00
435.00
350.00
3.50
5.00
7.00
0.4500
0.4500
0.4500
1.0000
1.0000
1.0000
2
1/477.1
39,2
2 . 28.3
1 | 6443
2
#3 1
2
0.320
0.370
190.00
250.00
10.00
8.00
0.4500
0.4500
1.0000
1.0000
2,189.0
1 35.5
1 266.5
2
#4 1
2
2
#5 1
2
2
#6 1
2
.0.320
0.370
0.246
0.320
0.350
0.370
500.00
315.00
500.00
500.00
275.00
360.00
10.00
6.30
8.00
6.70
7.10
8.30
0.4500
0.4500
0.4500
0.4500
0.4500
0.4500
1.0000
1.0000
1.0000
1.0000
1.0000
1.0000
%489.4
1 326.0
1 214.5
3,029.8
2
7273
1 | 115.1
3,872.1
1
113.1
1 ' | 820.0
2
#7 1
2
0.279
0.320
390.00
300.00
6.70
5.40
0.4500
0.4500
1.0000
1.0000
4,804.7
2 406.6
1 ' 39.2
2
#8 . 1
2
0.320
0.333
160.00
440.00
12.50'
8.20
0.4500
0.4500
1.0000
1.0000
1
5,250.4
2743
1 i 572^
2
#9 1
2
0.365
0320
375.00
375.00
7.60
7.00
0.4500
0.4500
1.0000
1.0000
1
1
2
6,095.5
784.1
124.8
7,004.2
Peak
Sediment
Cone.
(mg/i)
137,017
78397
65,611
86,O19
55399
84,199
159,109
99,259
128,519
137,773
99,890
239,271
122,434
110,345
150,082
135,948
120,640 .
117,339
188,469
126,327
147,302
85371
144,849
201,561
1S4,917
154,019
182,553
129,681
155,091
pea*
Seffleable
Cone
(ml/1)
35.57
11.44.
937
15.54
36.06 "
57.70
21.76
18.12
3337
35.77
19.13
62.12
31.79
22.47
94.43
35.30
34.36
30.46
19.04
31.92
100.94
22.16
41.43
24.88
22.08
4O.49
25.29
16.01
38.22 •
24VW
(ml/1)
19.65
6.17
5.16
832
18.07
26.44
11.83
9.61
17^62
19.77
10.46
33.22
17.54
12.O2
47.79
19.09
17.72
16.57
10.50
16.88
48.11
11.65
19.11
13.43
12.07
18.46
13.79
8.56
17.89
Subwatershed Time of Concentration Details:
Stm
#1
»
1
Land Flow Condition
7. Paved area and small upland
gullies
Slope (%)
4.71
(ft)
30.00
(ft) ((ps)
636.28 4.370
Time (hrs)
0.040
Appendix D
D-17
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
'
Stru
31
#1
31
01
#1
02
32
02
#2
02
32
03
33
03
33
04
34
* ' "™| " ' ...
S^ Land Row Condition
8. Large gullies, diversions, and tow
flowing streams
1 Time of Concentration:
7. Paved area and small upland
2 guMies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
2 Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
3 Time of Concentration:
7. Paved area and small upland
1 gullies
8. Large gullies, diversions, and low
flowing streams
1 Time of Concentration:
- 7. Paved area and small upland
z gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
2 Time of Concentration:
7. Paved area and small upland
3 gullies '
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
3 Time of Concentration:
7. Paved area and small upland
1 gullies
9. Small streams flowing bankfull
1 Time of Concentration:
7. Paved area and small upland
2 gullies
8. Large gullies, diversions, and low
flowing streams
2 Time of Concentration:
7. Paved area and small upland
1 gullies
a Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
1 Time of Concentration:
Slope (%)
3.49
8.78
3.22
1.86
. 3.12
2.38
3.04
2.57
3.27
ass
3.00
1.73
3.19
1.07
7.32
1.61
2.34
3.72
7.59
5.21
2.29
VertDlst
(ft)
57.00
70.00
29.00
69.00
38.00
28.00
27.00
26.00
20.00
19.00
13.00
• 14.00
29.00
15.00
43.00
10.00
15.00
49.00
20.00
39.00
22.00
Moriz-Dist.
(ft)
1,634.92
796.90
901.46
3,706.88
1,216.03
1,177.90
887.69
1,012.77
611.13
221.34
433.36
807.05
908.12
1,400.03
587.07
620.27
Velocity
(fps)
5.600
5.960
5.380
12.270
3.550
4.620
3.510
4.800
3.640
8.780
15.580
2.650
5.360
9.310
'5.440
11.420
640.64 3.080
I,3iai9 S.780
263.53 5.540
748.80 6.840
959.65 13.620
Time (hrs)
0.081
a 121
0.037
0.046
0.083
O.166
0.095
0.070
0.165
0.070
' 0.058
O.128
0.046
0.007
0.007
O.O6O
0.084
0.047
0.041
0.172
0.029
0.015
O.O44
0.057
0.063
O.12O
0.01
0.030
0.01
0.06
•
D-18
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Stru
*
04
*4
#B
*K
#5
#!i
#6
#6
#6
#6
#7
#7
#'/
#7
#8
#8
#8
#8
sws
*
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
Land How Condition
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
time of conLAnuAuon.
Slope (%)
4.66
4.06
10.69
3.21
2.10
5.10
7.93
1.59
6.54
1.11
2.09
2.77
4.99
6.74
6.30
10.22
1.20
4.21
5.56
0.94
0.99
5.86
Vert. Dist
(It)
14.00
56.00
82.00
" 88.00
72.00
34.00
21.00
5.00
52.00
13.00
43.00
43.00
.
30.00
110.00
27.00
34.00
5.00
34.00
44.00
15.00
11.00
104.00
Horiz. Dist.
(ft)
300.11
1,378.22
766.79
2,739.55
3,420.75
666.96
264.77
315.33
795.56
1,174.34
2,057.51
. 1,551.00
601.66
1,630.98
428.51
332.75
417.71
807.08
791.87
1,591.17
1,110.10
1,774.62
Velocity
(fps)
4.340
6.040
6.580
5.370
13.050
4.540
8.440
11330
5.140
9.460
2.910
4.990
4.490
23.370
5.050
9.580
9.B40
4.130
7.070
8.730
2.000
7.260
Time (hrs)
0.019
0.063
0.082
0.032
0.141
0.072
0.245
0.040
0.008
0.007
O.O55
0.042
0.034
O.O76
0.196
0.086
0.282
0.037
0.019
O.056
0.023
0.009
0.011
O.O43
0.054
0.031
0.050
O.135
0.154
0.067
a 221
Appendix D
D-19
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Stru
*
*9
*9
S9
«9
«MIS — ,~ » Vert Dist Hortz. Dist
^ Land Row Condition Stops (%) (ft) (ft)
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
1 Time of Concentration:
7. Paved area and small upland
* gullies
8. Large gullies, diversions, and low
flawing streams
9. Small streams flowing bankfull
2 Tim« of Concentration:
5.23
5.43
3.64
3.64
1.91
39.00
114.00
42.00
26.00
• 8.00
746.34
2,097.55
1,154.32
714.95
418.23
V^ Timers)
4.600
6.990
3.830
5.720
12.440
0.045
0.083
a 128
0.083
• 0.034
0.009
0.126
Subwatershed Muskingum Routing Details:
Stru
$
#1
#1
#2
#3.
SWS
0
1
1
1
1
Land How Condition
9. Small streams flowing bankfull
HuskingurnK:
9. Small streams flowing bankfull
Muakmgum K:
Stope(%, %°<* »"«*• "*£« T,me(hrs,
1.94 91.00 4,701.50 12J20 0.104
0.104
2.82 26.00 923.06 15.100 0.016
0.016
D-20
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subi
The average annual sediment yield numbers presented in Table 6b, in Section 6, were calculated
by using the pond design feature in SEDCAD 4.0. By putting a fictitious pond at the bottom of
the model, SEDCAD calculated the amount of sediment storage needed to store the sediment
yield. The fictitious pond structure details along with the estimate of the sediment storage is
presented on the following pages.
Structure Deta/7;
Structure #9 (Pnnrf)
Structure
Pond Inputs:
Initial Pool Elev:
4,612.58
Initial Pool:
0.01 ac-ft
*Sediment Storage:
8.29 ac-ft
Dead Space:
20.00%
*Sediment capacity based on A verage Annual R of 30. Oforl yearfs)
Emergency Spillway
Spillway Bev
4,625.00
Crest Length
(ft)
50.00
Left
Sktestope
2.00:1
Right
Skteslope
2.00:1
Bottom
Width (ft)
40.00
Pond Results:
Peak Elevation:
4,625.31
H'graph Detention Time:
6.79 hrs
Pond Model:
CSTRS
DewaterTime:
0.63 days
Trap Efficiency:
100.00%
Dewatering time is calculated from peak stage to lowest spillway
ElevaBon-CaDacity-Dischargp Tahio
Elevation
4,612.58
4,612.58
4,613.00
4,613.50
4,614.00
4,614.50
4,615.00
4,615.50
4,616.00
1 4,616.50
Area
(ac)
1.977
1.979
2.113
2.278
2.450
2.629
2.813
3.004
3.200
3.403
Capacity Discharge ^^
urns
(3C-ft) W CM
0.000
0.008 '
0.867
1.964
3.146
4.416
5.776
7.230
8.780
10.431
0.000 Top of Sed. Storage
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Appendix D
D-21
-------
Development Document - Proposed Western Alkaline
Coal Mining Subcategory
•
„ ir
'' '!'
Elevation
4,617.50
4,618.00
4,618.50
4,619.00
4,619.50
4,620.00
4,620.50
4,621.00
4,621.50
4,622.00
4,622.50
4,623.00
4,623.50
4,624.00
4,624.50
4,625.00
4,625.31
4,625.50
4,626.00
4,626.50
4,627.00
4,627.50
4,628.00
4,628.50
4,629.00
4,629.50
4,630.00
4,630.50
4,631.00
4,631.50
4,632.00
4,632.50
4,633.00
4,633.50
4,634.00
4,634.50
4,635.00
4,635.50
4,636.00
4,636.50
4,637.00
Area
(ac)
3.828
4.050
4.278
4.513
4.753
5.000
5.168
5339
5.513
" 5.689
5.868
6.050
6.235
6.423
6.613
6.806
6.926
7.002
7.200
7.402
7.606
7.813
8.022
8.235
8.450
8.668
8.889
9.113
9.339
9.568
9.800
10.035
10.272
10.513
10.756
11.001
11.250
11.501
11.756
12.013
12.272
Capacity
(ao-ft)
14.045
16.014
18.096
20.294
22.610
25.048
27.590
30.216
32.929
35.730
38.619
41.598
44.670
47.834
51.093
54.447
56.560
57.899
61.449
65.100
68.851
72.706
76.664
80.728
84.900
89.179
93.568
98.069
102.682
107.408
112.250
117.209
122.286
127.482
132.799
138.238
143.801
149.489
155.303
161.245
167.316
Dfccharge °—
(*> (hrs)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000 Spillway #1
22.662 15.15 Peak Stage
37.027
74.055
171.123
276.389
408.617
563.449
745.101
946.944
1,168.597
1,409.825
1,670.496
1,950.549
2,249.978
2,568.817
2,907.132
3,265.013
3,603.927
3,958.868
4,372.167
4,805.522
5,259.089
5.733.029
6,227.508
6,742.698
;, ; '•:
i ' ' -
D-22
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Elevation Emergency
tievatron Spittww (cfe)
4,616.00
4,616.50
4,617.00
4,617.50
4,618.00
4,618.50
4,619.00
4,619.50
4,620.00
4,620.50
4,621.00
' 4,621.50
4,622.00
4,622.50
4,623.00
4,623.50
.4,624.00
4,624.50
4,625.00
4,625.50
4,626.00
4,626.50
4,627.00
4,627.50
4,628.00
4,628.50
4,629.00
4,629.50
4,630.00
4,630.50
•4,631.00
4,631.50
4,632.00
4,632.50
4,633.00
4,633.50
4,634.00
4,634.50
4,635.00
4,635.50
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
37.027
74.055
171.123
276.389
408.617
563.449
745.101
946.944
1,168.597
1,409.825
1,670.496
1,950.549
2,249.978
2,568.817
2,907.132
3,265.013
3,603.927
3,958.868
4,372.167
4,805.522
5,259.089
Combined
Total
Discharge
(cfe)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
37.027
74.055
171.123
276.389
408.617
563.449
745.101
946.944
1,168.597
1,409.825
1,670.496
1,950.549
2,249.978
2,568.817
2,907.132
3,265.013
3,603.927
3,958.868
4,372.167
4,805.522
5,259.089
Appendix D
D-23
-------
: L Development Document - Proposed Western Alkaline Coal Mining Subcategory
*"*» '
4,636.00
4,636.50
4,637.00
4,637.50
4,63aOO
4,638.50
4,639.00
4,639.50
4,640.00
4,640.50
4,641.00
4,641.50
4.642.00
4,642.50
4,643.00
4,643.50
4,644.00
4,644.50
4,645.00
4,645.50
4,646.00
4,646.50
4,647.00
4,647.50
4,648.00
4,648.50
4,649.00
4,649.50
4,650.00
5,733.029
6,227.508
6,742.698
7,278.774
7,835.915
8,414.301
9,014.114
9,635.539
10,27&760
10,943.960
11,631.330
12,341.060
13,073.320
13,828.310
14,606.220
15,407.220
16,231.500
17,079.260
17,950.660
18,845.900
19,765.160
20,708.610
21,676.450
22,668.840
23,685.980
24,728.020
25,795.160
26,887.570
28,005.420
Combined
Total
Discharge
(cfe)
5,733.029
6,227.508
6,742.698
7,278.774
7,835.915
8,414.301
9,014.114
9,635.539
10,278.760
10,943.960
11,631.330
12,341.060
13,073.320
13,828.310
14,606.220
15,407.220
16,231.500
17,079.260
17,950.660
18,845.900
19,765.160
20,708.610
21,676.450
22,668.840
23,685.980
24,728.020
25,795.160
26,887.570
28,005.420
D-24
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Appendix D: Exhibit D-2
SEDCAD 4.0 Output
for
Postmining Reclaimed Conditions; Existing
Guidelines
Appendix D
D-25
-------
I
Development Document - Proposed Western Alkaline Coal Mining Subcategory
General information
Storm Information.-
StormType: NRCSTypeH |
=••, : Design Storm: idyr-24hrl
".: Rainfall Depth: L8i» indies'
Particle Size Distribution -
• iif "If!
il.
Size torn)
2.0000
0.1000
0.0500
0.0020
psdl
100.000%
83.500%
77.000%
56.000%
psd2
100.000%
30.000%
17.000%
11.000%
psd3
60.000%
15,900%
8.400%
6.6pO%
psd4
100.000%
26.500%
14.000%
11.000%
D-26
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Structure Networking:
Type
Null
Null
Null
Null
Null
Null
Null
Null
Null
Null
Null
Null
Null
Null
Null
Pond
Pond
Pond
Stni (flows Stru
• # into) #
#1 ==> #2
#2 ==> #3
#3 — > #4
#4 ==> #5
#5 -=> #6
#6 -=> #7
#7 ==> #8
#8 ==> #9
#9 -=> #16
#10 ==> #n
#11 ==> #2
#12 ==> #5
#13 -=> #14
#14 ==> #7
#15 ==> #9
#16 ==> #17
#17 ==> #18
#18 ==> End
Musk. K M
(hrs) Musk-X
0.050 0.429
0.018 0.435
0.029 0.433
0.011 0.445
0.057 0.414
0.023 0.428
0.060 0.4.19
0.048 0397
0.000 O.QQO
0.027 0.448
0.075 0.435
0.029 0.449
0.019 0.449
0.038 0.447
0.051 0.449
0.000 0.000
0.000 0.000
0.000 0.000
Description •
Structure #2
Structure #3
Structure #3
Structure #4
Structure #5
Structure #6
Structure #7
Structure #8
Structure #9
Structure #10
Structure #11
Structure #12
Structure #13
Structure #14
Structure #15
>ond#l
'ond#2
>ond#3
Appendix D
D-27
-------
DC.
Proposed Western Alkaline Coal Mining Subcategory
ill* ',.' i
Stru
#
#11
#11
#12
#12
#13
#13
#14
#14
#15
#15
Land Row Condition
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
Slope (%)
1.58
2.80
2.79
2.52
2.82
Vert Dist
(ft)
49.00
45.00
30.00
50.00
79.00
Horiz. Dist
(ft)
3,097.14
1,609.09
1,076.50
1,981.84
2,798.44
Velocity
(fps)
11.32
15.05
15.02
14.29
15.12
Time (hrs)
0.075
0.075
0.029
0.029
0.019
0.019
0.038
0.038
0.051
0.051
D-28
Appendix
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
# "
Null
Null
#16
Pond
& #17
Pond
#18
Pond
Structure Routing Details:
Stni
#
#1
#1
#2
#2
#3
#3
#4
#4
#5
#5
#6
#6
#7
#7
#8
#8
#10
#10
Land Row Condition
9> Small streams flowing bankfuil
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum JO
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum 10
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Muskingum K:
Slope (%)
1.30
1.60
1.47
2.38
0.83
1.27
0.95
0.53
2.66
VertDist
(ft)
-24.00
12.00
17.00
14.00
14.00
11.00
18.00
6.00
38.00
Horiz. DisL
(ft)
1,847.57
751.55
1,153.01
587.93
1,686.68
866.89
1,900.33
1,139.38
1,428.73
Velocity
(fps)
10.25
11.37
10.92
13.88
8.19
10.13
8.75
6.53
14.67
Time (hrs)
0.050
0.050
0.018
0.018
0.029
0.029
0.011
0.011
0.057
0.057
0.023
0.023
0.060
0.060
0.048
0.048
0.027
0.027
Appendix D
D-29
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Structure Summary:
Immediate Total
Contributing Contributing r
Area Area
(ac) (ac)
#15
#13
#14
#12
#10
#11
#1
#2
#3
#4
#5
#6
#7
#8
#9
In
#16
Out
In
#17
Out
In
#18
Out
33.912
74.497
41522
87386
35.153
46.192
288.818
154.453
31.628
45500
38578
101.562
46.416
87.666
75240
0.000
0.000
0.000
33.912
74.497
116.019
87386
35.153
81345
288.818
524.616
556.244
601.744
727.708
829270
991.705
1,079371
1,188523
1,188523
1,188523
1,188523
Peak Total
A, si
(cfe) (ac-ft)
752
17.08
23.22
33.10
13.16
23.03
24426
32056
354.80
394.83
445.51
493.50
522.07
555.78
601.89
601.89
388.93
388.93
144.52
14452
44.79
0.78
1.68
2.59
2.42
1.26
2.28
2726
Sediment
(tons)
243
64.2
89.8
154.0
96.9
145.4
1,477.1
37.80 1 2313.0
40.64
43.89
47.66
2,615.0
2,886.8
3,1305
56.00 ! 4,068.0
59.81
66.15
72.93
72.93
58.44
4,196.6
4,906.1
5,611.1
5,611.1
2,665.9
72.93 2,665.9
54.68 1,515.9
72.93
48.83
1515.9
666.1
Peak Peak
Sediment Setteable
Cone Cone.
(mg/l) (ml/0
56,094
73318
98,626
99,183
142552
121,806
86,019
103,515
102,682
101,460
102214
111,723
108,988
115,962
114,800
' 114,800
53,621
53,602
37,656
37,643
28,235
25.64
5027
66.96
6821
96.84
82.73
15.54
21.70
22.12
22.43
25.60
24.80
25.53
25.84
25.86
25.86
0.00
0.00
" 0.00
0.00
0.00
24VW
(ml/I)
10.88
19.19
17.97
30.77
4022
33.13
832
10.80
1153
11.94
1338
13.17
13.35
13.44
13.96
13.96
0.00
0.00
0.00
0.00
0.00
D-30
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Pond #1
Pond Inputs:
Initial Pod Sev:
Initial Pool:
*Sediment Storage:
Dead Space:
4,620.80
0.01 ac-ft
6.70 ac-ft
20.00 %
*Sediment capacity was entered by user
Emergency Soillwav
Spillway Elev
4,625.50
Crest Length
(ft)
20.00
Left '
Sideslope
2.00:1
Right
Sideslope
2.00:1
Bottom
Width (ft)
50.00
Pond Results:
Peak Elevation:
H'graph Detention Time:
Pond Model:
DewaterTime:
Trap Efficiency:
4,627.49
1.38 hrs
CSTRS
1.30 days
52.49 %
Dewatering time is calculated from peak stage to lowest spillway
Elevation-Capacitv-DischaraeTahlc
Elevation
4,620.80
4,620.80
4,620.81
4,621.00
4,621.50
4,622.00
4,622.50
Area
(ac)
1.842
1.843
1.847
1.909
2.080
2.257
2.442
Capacity Discharge D5rater
Time
(ac-ft) (cfs) (his)
0.000
0.008
0.027
0.384
1381
2.465
3.639
0.000 Top ofSed. Storage
0.000
0.000
0.000
0.000
0.000
0.000
Appendix D
D-31
-------
>.d Western Alkaline Coal Mining Subcategory
Design .
•
.,
Elevation
4,623.00
4,623.50
4,624.00
4,624.50
4,625.00
4,62550
4,625.75
4,626.00
4,626.50
4,627.00
4,627.49
4,627.50
4,628.00
4,628.50
4,629.00
4,62950
4,630.00
Area
(ac)
2.633
2.832
3.039
3.252
3.473
3.701
3.818
3.937
4.179
4.429
4.683
4.686
4.950
5,522
5.501
5.787
6.080
Capacity
(ac-ft)
4.907
6.273
7.741
9314
10.995
12.788
13.728
14.697
16.726
18.878
21.126
21.156
23.565
26.108
28.788
31.610
34.576
Discharge °^f
<•<& (hrs)
0.000
0.000
0.000
0.000
0.000
0.000 Spillway #1
4.504 17.15
9.008 1.90
117.195 11.25
236.895 0.45
388.930 035 Peak Stage
391.002
572.058
778.237
1,008372
1,261.680
1,537.619
Detailed Discharge Table
Combined
PI ««or, Emergency Total
Elevation s^nway (cfe) Discharge
(cfs)
4,620.80
4,620.80
4,620.81
4,621.00
4,621.50
4,622.00
4,622.50
4,623.00
4,623.50
4,624.00
4,624.50
4,625.00
4,625.50
4,625.75
4,626.00
4,626.50
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
4.504
9.008
117.195
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
4.504
9.008
117.195
D-32
ix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Structure #1R (Pnnrl)
Pond #3
Pond Inputs:
Elevation
4,603.50
4,603.75
4,604.00
4,604.50
4,605.00
4,605.50
4,606.00
4,606.50
4,607.00
4,607.50
4,608.00
4,608.50
4;609.00
4,609.50
4,610.00
Emergency
Spillway (ds)
0.000
0.000
0.000
7.214
94.261
191.122
316.440
464.388
633.655
823.441
1,033.244
1,262.749
1,511.766
1,780.193
2,067.994
Combined
Total
Discharge
(ds)
0.000
0.000
0.000
7.214
94.261
191.122
316.440
464388
633.655
823.441
1,033.244
1,262.749
1,511.766
1,780.193
2,067.994
Initial Pool Efev:
4,580.88
Initial Pool:
0.02 ac-ft
*Sediment Storage:
6.70 ac-ft
Dead Space:
20.00%
*Sediment capacity was entered by user
Spillway Bev
4,586.50
Crest Length
(ft)
20.00
Left
Sideslope
2.00:1
Right
Sideslope
2.00:1
Bottom
Width (ft)
30.00
Pond Results:
Peak Elevation:
4,587.30
H'graph Detention Time:
3.42 hrs
Pond Model:
CSTRS
DewaterTime:
0.68 days
Trap Efficiency:
56.06 %
Dewatering time is calculated from peak stage to lowest spillway
Appendix D
D-33
-------
nwlnnwnt Document - Proposed Western Alkali™ Coal Mining Subcategor
Pond#2
Pond Inputs:
"—
Elevation
4,627.00
4,627.50
4,628.00
4,628.50
4,629.00
4,629.50
4,630.00
Emergency
Spillway (cfe)
236.895
391.002
• 572.058
778.237
1,008.372
1,261.680
1,537.619
Combined
Total
Discharge
(cfs)
236.895
391.002
572.058
••
778.237
1,008.372
1,261.680
1,537.619
Initial Pool Bev:
Initial Pool:
*Sediment Storage:
Dead Space:
4,599.52
0.03 ac-ft
6.70 ac-ft
20.00 %
*Sediment capacity was entered by user
Pond Results:
1 ' " !' i !|
Flevation-Capadtv-Discharae Table
,| •::
Bevation
4^99.51
4,599.52
Area
(ac)
2.099
2.105
_^^>^^-^^— ^^— ^^— ^
Capacity
(ac-ft)
0.000
0.028
; ;
Discharge
(cfs)
0.000
0.000
Dewater
Time
(hrs)
Top of Sed. Storage
'•—
1 ... i
D-34
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
.
*D
Elevation
4,600.00
4,600.50
4,601.00
4,601.50
4,602.00
4,602.50
4,603.00
4,603.50
4,603.75
4,604.00
4,604.50
4,605.00
4,605.26
4,605.50
4,606.00
4,606.50
4,607.00
4,607.50
4,608.00
4,608.50
4,609.00
4,609.50
4,610.00
^esignates time(s)
Area
(ac)
2.320
2.469
2,623
2.782
2.945
3.113
3.286
3.463
3.554
3.645
3.832
4.023
4.126
4.219
4.419
4.624
4.834
5.048
5.267
5.491
5.719
5.952
6.190
Capacity
(ac-ft)
1.089
2.286
3.559
4.911
6.342
7.857
9.456
11.144
12.021
12.921
14.790
16.753
17.822
18.813
20.973
23.233
25.598
28.068
30.647
33.336
36.139
39.057
42.092
to dewater have been
Discharge Dewater
(Cfe) (h™
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000 Spillway #1
7.214 3.14*
94.261 11.70
144.525 0.60 Peak Stage
191.122
316.440
464.388
633.655
823.441
1,033.244
1,262.749
1,511.766 "
1,780.193
2,067.994
extrapolated beyond the SO hour hydrograph limit
Detailed Di
Elevation
4,599.51
4,599.52
4,600.00
4,600.50
4,601.00
4,601.50
4,602.00
4,602.50
4,603.00
Spillway (cfs)
0.000
0.000
0.000
• o.ooo
0.000
0.000
0.000
0.000
0.000
Combined
Total
Discharge
(cfs)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Appendix D
D-35
-------
Develo
Proposed Western Alkaline Coal Mining Subcategory
I
Eievation-Capacitv-Discharae Table
Elevation
4,580.87
4,580.88
4,581.00
4,581.50
4,582.00
4,582.50
4,583.00
4,583.50
4,584.00
4,584.50
4,585.00
4,585.50
4,586.00
4,586.50
4,587.00
4,58730
4,587.50
4,588.00
4,588.50
4,589.00
4,589.50
4,590.00
Area
(ac)
1.720
1.722
1.744
1.833
1.926
2.020
2.117
2.216
2.318
2.421
2.527
2.635
2.745
2.858
2J973
3.044
3.090
3.210
3.331
3.455
3.582
3.710
Capacity Discharge
(ac-ft) (cfs)
0.000
0.018
0.226
1.120
2.060
3.046
4.080
5.164
6.297
7.482'
8.718
10.009
- 11.354
12.755
14.212
15.118
15.728
17.303
18.938
20.635
22.394
24.217
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
-5.419
44.786
71.329
145.356
241.897
356.760
489.149
638.637
ewater
(hrs)
Top of Sed. Storage
Spillway #1
3:25*
12.95 Peak Stage
^Designates time(s) to dewaterhave been extrapolated beyond the SO hour hydrograph limit
Detailed Discharge table
r 'ii. ,"'! ;• •"•
Elevation
4,580.87
4,580.88
4,581.00
4,581.50
4,582.00
4,582.50
4,583.00
4,583.50
4,584.00
Emergency
Spillway (ds)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Combined
Total
Discharge
(cfs)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
_— — ' ! Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Elevation
4,584.50
4,585 .OO
4,585. 5O
4,586 .OO
4,586.5O
4,587.OO
4,587.50
4,588 .OO
4,588.50
4,589. OO
4,589. SO
4,59O.OO
Emergency
Spillway Ccfs)
O.OOO
O.OOO
O.OOO
O.OOO
O.OOO
5.419
"71..329
145.35©
241.897
356. 76O
489.149
638.637
Combined
Total
Discharge
Ccfs)
O.OOO
O.OOO
O.OOO
O.OOO
O.OOO
5.419
71.329
145.356
241.897
489.149
638.637
Appendix D
D-37
-------
•velopment Document -rroposea wu*itiinj\uu*um, ^u^^i..^-^ ~^*^_±, — ^ . .
Subwatershed Hydrology Detaili
•
Stru SWS SWSArea.
# # (ac)
#15 1 3.038
2 12.123
3 8.741
4 10.010
2 33.912
#13 1 22.100
2 10.547
3 7328
4 13.158
5 13.826
6 7.538
i1 ' •
£ 74.497
#14 1 16.221
2 13.248
3 12.053
2 116.019
#12 1 40.766
2 7.113
3 29.932
4 9.575
2 87.386
#10 1 20.295
2 14.858
2 35.153
#11 1 8.414
2 11322
3 5.500
4 14.513
5 6.443
Time of
Cone
(hrs)
0.100
0.100
0.100
0.147
0.085
0.020
0.017
0.033
0.231
0.073
0.036
0388
0250
0.116
0.014
0.057
0.080
0.065
0.237
0.019
0.041
0.053
0.304
0.122
MuskK
(hrs)
0.065
0.023
0.000
0.000
0.016
0.000
0.191
0.158
0.000
0.000
0.000
0.000
0.000
0.048
0.035
0.000
0.000
0.000
0.000
0.020
0.007
0.000
0.000
0.000
MuskX
0.378
0.396
0.000
0.000
0.455
•0.000
0316
0301
0.000
0.000
0.000
0.000
0.000
0.442
0.444
0.000
0.000
0.000
0.000
0.436
0.431
0.000
0.000
0.000
Peak
QBVe UHS Discharge
Number (cfe)
93.000 M i 3.42
65.000 S 0.50
74.000 M j 2.61
74.000 M
1.56
7.52
79.000 M 10.53
65.000 S
81.000 M
65.000 S
74.000 M
74.000 ' M
74.000 M
0.43
4.07
0.54
1.89
2.25
17.08
4.85
74.000 M • 1-40
74.000 M 1
1.59
23.22
80.000 M | - 21.01
65.000 S i 0.29
74.000 M
74.000 M
8.94
2.86
! 33.10
80.000 M | 10.46
79.000 M '• 3.68
13.16
79.000 M ' 1 4.01
65.000 S ! 0.47
74.000 M
74.000 M
79.000 M
2 8L345
#1 1 44.593
E2 140.138
3 104.087
.:..;
0.121
0.166
0.165
0.104
0.000
0.000
0.440
0.000
0.000
93.000 M
93.000 M
1.64
1.75
3.07
23.03
50.25
111.94
93.000 M | 83.14
Runoff
Volume
(ac-ft)
0.287
0.086
0.190
0.218
0.781
0.755
0.075
0.294
0.094
0.301
0.164
1.683
0.353
0.288
0.262
2.586
1.511
0.051
0.651
0.208
2.421
0.752
0.507
1.259
0.287
0.081 j
0.120
0.316
0.220
£283
4.209
13.227
9.824
"•
Appendix
D-38
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Stnu SWS SWSArea
* * (ac)
Appendix D
D-39
-------
dopment Document - Pr
, ;., 5
SOU SWS <
# #
#15 1-
L__2 _
—
H — ~
2
#13 1
2
3
4
5
r-
2
#14 1
2
3
2
] #12 1
2
3
4
2
1 #10 i
1 2
S
1 #11 1
j 2
1 ~" 3
4
5
2
#1 i
1 2
\ 3
[ #2 1
toilK
0370
Q.150
0240
0240
0240
0.150
0290
0.150
0.240
0240
0.240
0.240
0240
0260
0.150
0240
0240
0290
0250
0290
0.150
0240
0240
0240
0370
0370
0370
0240
oposed Western Alkaline Coal Mining Su
ubwatershed Sedimentol
.^.-a^—
L(ft) S
100.00
450.00
450.00
475.00
500.00
250.00
100.00
450.00
250.00
275.00
375.00
385.00
375.00
340.00
250.00
375.00
400.00
650.00
750.00
250.00
500.00
450.00
475.00
400.00
650.00
800.00
850.00
550.00
(%)
650
6.00
6.00
9.00
5.00
6-.00
6.40
5.00
5.00
9.00
6.60
8.00
530
730
6.00
550
6.40
7.00
3.50
11.00
6.00
6.00
5.00
2.60
450
3.00
250
2.90
__
C
0.4500
03100
0.1800
0.6300
0.4500
03100
0.4500
03100
03000
0.4500
0.5500
0.6300
0.4900
0.4500
03100
0.4800
0.4500
0.4500
0.4500
0.4500
03100
0.0530
0.6300
0.4500
0.4500
0.4500
0.4500
0.4900
P PS#
1.0000 1
0.4700 3
0.4500 4
7category
ogyDei
&//
„ ,'• » , liiiln,
Peak Peak
Sediment Sediment Seffleable
(tons)
(mg/l) (ml/I)
12.4
0.6
1.9
0.4700 4 9.3
24.3
1.0000 2 452
0.4700 3
1.0000 2
0.4700 3
0.4500 4
0.4600 4
0.4700 4
0.4700 4
0.6300 4
0.4
10.7
05
2.2
5.2
64.2
12.4
7.7
55
89.8
1.0000 2
0.4700 3
0.5100 4
0.6900 4
125.9
02
19.6
83
154.0
1.0000 2 85.4
1.0000 2
1.0000 2
11.5
96.9
37.5
0.4700 3 ' 0.5
0.4400 4 i 0.3
0.4500 4
1.0000 2
6.2
3.9
145.4
1.0000 1 ! 452.3
1.0000 1 633.3
1.0000 1 ! 391.6
1,477.1
0.6300 4 i 28.8
57r
10,
526
413
18279
80383
56,094
93,826
7,641
53
6
,728
567
13,681
55,978
73,318
61,717
4C
3£
98
>217
!327
,626
126,187
7290
53,055
69563
99,183
168,832
40,689
142,562
195593
10,885
5,005
35,604
28,804
121,806
137,017
78397
65,611
86,019
33,224
14.94
7.70
12.77
52.56
25.64
64.30
5.65
36.82
4.85
8.80
39.11
50.27
43.12
28.60
24.53
66.96
86.47
_ 539
37.07
48.60
68.21
115.70
25.82
96.84
134.04
8.05
350
22.48
19.74
82.73
35.57
11.44
9.57
15.54
23.21
24VW
(ml/1)
8.13
3.50
524J
, —
24.87
10.88
2951
257
18.11
2.97
16.15
19.19
17.82
15.10
12.08
. :
17.97
40.64
2.45
20.12
30.77
54.71
13.02
40.22
62.46
3.66
1.43
113E
8.97
33.12
19.6!
6.1"
5.K
8.3
9.5
[
1
}
- -- --------'
D-40
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
.
f 7 -"
2 0.240
3 0.355
2
#3 1 0320
2 0370
— -^— — — . _^_
L(ft)
250.00
350.00
190.00
250.00
s«
8.20
7.00
10.00
8.00
C
0.4500
0.4500
0.4500
0.4500
P PS#
1.0000 2
1.0000 1
Sediment
(tons)
i
17.4
644.3
2,313.0
1.0000 1 | 355
1.0000 1
2
#4 1 0320
2 0370
3 0.240
125.00
315.00
500.00
8.00
630
6.40
0.4500
0.4500
0.4500
1.0000 1
1.0000 1
0.6900 4
2
#5 1 0320
2 0540
2
#6 1 0370
2 0350
' 3 0.240
225.00
320.00
360.00
275.00
500.00
7.50
8.00
830
7.10
6.00
0.4500
05100
0.4500
0.4500
0.4500
1.0000 .1
0.7200 4
1.0000 1
1.0000 1 j
0.6900 4
2
#7 1 0.240
2 0320
3 0.240
300.00
300.00
525.00
5.40
5.40
3.80
0.4500
0.4500
0.4700
0.6900 4
266.5
2,615.0
47.7
214.5
9.7
2£86.8
50.0
39.7
3,130.5
820.0
1033
14.5
4,068.0
3.6
1.0000 1 18.0
0.6700 . 4
2
#8 1 0333
2 0.240
3 0.320
2
#9 1 0.365
2 0.320
2
#16 2
#17 2
#18 2
440.00
375.00
600.00
375.00
375.00
8.20
7.20
6.40
7.00
7.00
0.4500
0.4500
0.4500
0.4500
0.4500
1.0000 1
0.6900 4
17.3
4,196.6
572.2
15.2
1.0000 1 122.8
1.0000 1
1.0000 1
— — — -^ — -^— —
4,906.1
556.1
124.8
5,611.1
5,611.1
2,665.9
1,515.9
Peak
Sediment S
Oonc.
(mg/l)
95,832
159,109
103,515
128519
137,773
102,682
82584
122,434
77,880
101,460
95,476
103,274
102,214
188,469
116,261
77,023
111,723
48,834
78,755
39,426
108,988
184,917
79,460 '
147,976
115,962
160,140
129,681
114,800
114,800
53,602
37,643
—•— — •—
Peak
effleable
Cone
(ml/1)
65.67
21.76
21.70
3337
35.77
22.12
21.44
31.79
54.41
22.43
24.79
72.15
25.60
19.04
30.18
53.81
24.80
34.12
20.45
27.54
25.53
22.08
55.51
38.42
25.84
41.58
16.01
25.86
25.86
0.00
0.00
•^—^—i^— ••«.•_
24VW
(ml/I)
30.15
11.83
10.80
17.62
19.77
11.53
11.26
' 1754
2255
11.94
13.49
30.04
13.38
10.50
16.42
2230
13.17
14.07
10.74
1134
13.35
12.07
23.02
2033 1
13.44
22.77 1
8.56 1
13.96 1
13.96
0.00
0.00
Subwatershed Time of Concentration Details:
Anr>t>nsJjv D • — .
D-41
-------
;
' ™
•
-:,
'(
„!''
Sttu SWS
# #
#1 1
#1 1
#1 2
#1 2
#1 3
#1 3
#2 1
#2 1
#2 2
#2 2
#2 3
#2 3
#3 1
#3 1
#3 2
#3 2
#4 1
•
#4 1
#4 2
Land Flow Condition
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankroll
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies .
8. Large gullies, diversions, and low
flowing streams
Slope (%)
4.71
3.49
8.78
3.22
1.86
3.12
238
3.17
3.12
6.12
2.58
1.73
3.19
1.07
732
1.61
2.34
3.72
9.60
2.29
4.66
4.06
Vert Dist Horiz. Dist
(ft) (ft)
30.00
57.00
70.00
29.00
69.00
38.00
28.00
40.00
32.00
30.00
17.00
14.00
29.00
15.00
43.00
10.00
15.00
49.00
60.00
22.00
14.00
56.00
636.28
1,634.92
796.90
901.46
3,706.88
1,216.03
1,177.90
1,262.82
1,025.90
490.00
660.01
807.05
908.12
1,400.03
587.07
620.27
640.64
1,318.19
625.00
959.65
300.11
1,378.22
Velocity
(fps)
4.370
5.600
5.960
5.380
12.270
3.550
4.620
3.580
15.890
4.980
14.440
2.650
5.360
9310
5.440
11.420
3.080
5.780
6.230
13.620
4.340
Time (hrs)
0.040
0.081
0.121
0.037
0.046
0.083
0.166
0.095
0.070
0.165
0.097
0.017
0.114
0.027
0.012
0.039 1
0.084
0.047
0.041
0.172
0.029
0.015
0.044
0.057
0.063
0.120
0.027
0.019
0.046
0.01?
6.040 0.06:
1
1
. '; " • • " . *..• i ' • ! : -J^_
D-42
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Stni
#
#4
#4
#4
#5
#5
#5
#5
#6
#6
#6
#15
#6
#6
#7
#7
#7
#7
#8
#8
#8
#8
sws
# land Flow Condition
2 Time of Concentration:
, 7. Paved area and small upland
gullies
3 Time of Concentration:
« 7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
1 Time of Concentration:
2 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
2 Time of Concentration:
, 7. Paved area and small upland
gullies •
9. Small streams flowing bankfull
1 Time of Concentration:
? 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
2 Time of Concentration:
3 7. Paved area and small upland
gullies
3 Time of Concentration:
j 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
1 Time of Concentration:
, 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
3 Time of Concentration:
j 7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
1 Time of Concentration:
2 7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
2 Time of Concentration:
Slope (%)
9.00
10.69
3.21
2.10
4.65
3.04
6.54
1.11
8.00
1.87
9.40
4.99
6.74
5.87
5.43
4.21
5.56
0.94
9.12
5.65
1.36
VertCSst
(ft)
45.00
82.00
88.00
72.00
40.00
41.00
52.00
13.00
60.00
22.00
58.00
30.00
110.00
50.00
20.00
34.00
44.00
15.00
62.00
34.00
7.00
Horiz. Dist
(ft)
499.99
766.79
2,739.55
3,420.75
860.00
1,350.01
795.56
1,17434
750.00
1,174.33
617.12
601.66
1,630.98
851.98
368.03
807.08
791.87
1,591.17
679.65
602.23
516.18
Velocity
(fps)
6.030
6.580
5.370
13.050
4.340
15.680
5.140
9.460
5.690
12.310
6.170
4.490
23.370
4.870
20.980
4.130
7.070
8.730
6.070
7.120
10.480
Time (hrs)
0.082
0.023
0.023
0.032
0.141
0.072
0.037
0.055
0.023
0.078
0.042
0.034
0.282
0.036
0.026
0.062
0.027
0.027
0.037
0.019
0.100
0.048
0.004
0.052
0.054
0.031
0.050
0.221
0.031
0.023
0.013
0.067
ooendix D " ~ " —
D-43
-------
'!'!'! ! •" i, i' .i, "ll'iH"
: '
••• !
Stru SWS
# #
#8 3
#8 3
#9 1
#9 1
#9 2
#9 2
#10 1
#10 1
#10 2
#10 2
#11 1
#11 1
#11 2
#11 2
#11 3
#11 3
#11 4
#11 4
#11 5
#11 5
#12 4
:*'
11 ' '!„!• 1 • • i , ('•
land Flow Condition
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
Time of Concentration:
7. Paved area and small upland
gullies
6. Grassed waterway
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
6. Grassed waterway
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area' and small upland
gullies
6. Grassed waterway
j '
Slope (%)
8.33
0.75
732
2.60
3.64
3.64
1.91
8.23
5.22
3.74
1.00
9.62
4.53
6.00
1.77
4.93
139
321
1.00
3.71
1.00
730
l.OC
:, :.": . ,,';,:
' i, i • " ' •' «.'
,:;;:,,. •> ; ih:;
VertDist Horiz.Dist Velocity Time(hrs)
(ft) (ft) (fcs)
75.00
8.00
45.00
69.00
42.00
26.00
8.00
73.00
30.00
39.00
8.82
25.00
26.00
30.00
10.00
37.00
4.00
39.00
11.40
45.00
11.40
49.00
2.50
900.00
1,061.00
615.00
2,650.07
1,15432
714.95
41823
887.11
575.14
1,044.12
882.00
260.00
573.95
500.00
56634
750.00
288.43
1,214.57
.1,140.00
1,214.54
1,140.00
670.79
250.00
5.810
7.810
5.440
14.520
3.830
5.720
12.440
5.770
6.850
3.890
1.500
6.240
19.150
4.930
11.950
4.470
10.590
3.600
1.500
3.870
9.000
5.440
1.500
0.043
0.037
0.080
0.031
0.050
0.081
0.083
0.034
0.009
0.126
0.042
0.023
0.065
0.074
0.163
0.237
0.011
0.008
0.019
0.028
0.013
0.041
0.046
0.007
0.053
0.093
0.211
0.304
0.087
0.035
0.122
0.03"
0.04*
\
3
D-44
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
SOU
#
#12
#13
#13
#13
#13
#13
#13
#13
#13
#13
#13
#13
#13
#14
#14
#14
#14
#14
#14
#15
#15
£ Land Flow Condition
4 Time of Concentration:
, 7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
1 Time of Concentration:
2 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
2 Time of Concentration:
, 7. Paved area and small upland
gullies
3 Time of Concentration:
4 7. Paved area andsmall upland
gullies
4 Time of Concentration:
c 7. Paved area and small upland
s gullies
6. Grassed waterway
5 Time of Concentration:
6 7. Paved area and small upland
0 gullies
6. Grassed waterway
6 Time of Concentration:
, 7. Paved area and small upland
gullies
1 Time of Concentration:
2 7. Paved area and small upland
gullies
6. Grassed waterway
2 Time of Concentration:
3 6. Grassed waterway
3 Time of Concentration:
4 7. Paved area and small upland
gullies
6. Grassed waterway
4 Time of Concentration:
Slope (%)
4.96
3.61
6.00
5.88
4.00
4.08
4.40
1.00
8.27
1.00
5.60
831
1.00
1.00
10.67
1.00
Veit Dist
(ft)
30.00
36.00
15.00
30.00
10.00
20.00
22.00
10.77
31.00
3.00
35.00
27.00
20.16
13.53
40.00
7.14
Horiz. Dist
(ft)
605.00
997.22
' 250.00
510.00
250.00
490.00
500.00
1,077.00
375.00
300.00
625.00
325.00
2,016.00
1,353.00
375.00
715.00
Velocity
(fps)
4.480
5.690
4.930
21.820
4.020
4.060
4.220
1.500
5.780
1.500
4.760
5.800
1.500
1.500
6.570
1.500
Time (hrs)
0.080
0.037
0.048
0.085
0.014
0.006
0.020
• 0.017
0.017
0.033
0.033
0.032
0.199
0.231
0.018
0.055
0.073
0.036
0.036
0.015
0.373
0.388
0.250
0.250
0.015
0.132
0.147
Subwatershed Muskingum Routing Details:
Stru
#
#1
#1
#2
SWS
#
1
1
1
Land Row Condition
9. Small streams flowing bankfull
Muskingum K:
9. Small streams flowing bankfull
Slope (%)
1.94
2.99
Vert. Dist.
(ft)
91.00
20.00
Horiz. Dist
(ft)
4,701.50
669.47
Velocity
(fps)
12.520
15.550
Time (hrs)
0.104
0.104
0.011
Appendix D — • — —
-------
Deveh
snt Document - Proposed Western Alkaline Coal Mining Subcategory
Stru
#
#2
#4
#4
#6
#6
•#R
#B
#11
#11
#11
#11
#13
#13
#13
#13
#13
#13
sws
#
1
3
3
3
3
?
2
1
1
?
7
1
1
3
3
4
4
land Row Condition
Muskingum K:
7. Paved area and small upland
gullies
Muskingum K:
7. Paved area and small upland
gullies
MuskingumK:
9. Small streams flowing bankfull
MuskingumK:
9. Small streams flowing bankfull
MuskingumK:
9. Small streams flowing bankfull
MuskingumK:
9. Small streams flowing bankfull
Muskingum K:
7. Paved area and small upland
gullies
6. Grassed waterway
MuskingumK:
7. Paved area and small upland
gullies
6. Grassed waterway
Muskingum K:
Slope (%)
8.00
6.67
0.75
1.64
1.39
3.60
4.57
1.00
6.48
1.00
VerLDist
(ft)
20.00
20.00
8.00
14.00
4.00
36.00
36.00
7.65
21.00
7.65
Horiz.Dist
(ft)
250.00
300.00
1,061.00
854.80
288.43
998.86
787.43
765.00
324.00
765.00
Velocity
(fps)
5.690
5.190
7.810
11.510
10.590
17.080
4.300
1.500
5.120
1.500
Time (hrs)
0.011
0.012
0.012
0.016
0.016
0.037
0.037
0.020
0.020
0.007
0.007
0.016
0.016
0.050
0.141
0.191
0.017
0.141
0.158
K, ,- :•
D-46
Appendix D
-; ,, 'I j LI in M: ;,i lull.)! liiii^^ .it iimis ,i! t, i! ir,; ii; I- an: iti ;< MI ;:
-------
Development Document - Proposed Western Alkaline Coal Mining Subcatesorv
Appendix D: Exhibit D-3
SEDCAD 4.0 Output
for
Postmining Reclaimed Conditions, Proposed Subcategory
Appendix D
D-47
-------
fill j
Develoument
Document - Proposed Western Alkaline Coal Mining Subcategory
General Information
Storm Information:
Storm Type: NRG Type II
Design Storm; 10yr-24hr
Rainfall Depth: 1.800 inches
Particle Size Distribution:
Size (mm)
2.0000
0.1000
0.0500
0.0020
0.0010
psdl
100.000%
83.500%
77.000%
55.000%
0.000%
psd2
100.000%
30.000%
17.000%
11.000%
0.000%
psd3
60.000%
15.900%
8.400%
6.600%
0.000%
psd4
100.000%
26.500%
14.000%
11.000%
0.000%
D-48
Appendix L)
•]' ;'"( '»
-------
Development Document - Proposed Western Alkaline Coal Mini
Structure Networking:
Type
Null
Null
Null
Null
Null
Null
Stm (flows Stm
* into) *
#1 ==> #2
#2 .=> #3
#3 ==> #4
#4 ==> #5
#5 ==> #6
"£>" "**
0.050 0.429
Description
Structure #2
0.018 0.435 j Structure #3
0.029 0.433
0.011 0.445
0.057 0.414
#6 ==> #7 j 0.023 0.428
Null j #7 ==> #8
Null
Null
#8 ==> #9
#9 ==> Bid
Null ; #10 ==> #n
N"« I #11 ==> #2
Null
Null
Null
Null
#12 ==> #5
#13 ==> #14
#14 ==> #7
Structure #3
Structure #4
Structure #5
Structure #6
0.060 0.419 j Structure #7
0.048 0.397
0.000 0.000
0.027 0.448
0.075 0.435
0.029 0.449
0.019 0.449
0.038 0.447
Structure #8
Structure #9
Structure #10
Structure #11
Structure #12
Structure #13
Structure #14
#15 ==> #9 Q.OS1 0.449J Structure #15
*15
Null
*"
Null
*"
Null
"*
Null
Null
Null
Null
Null
Null
Null
Appendix D
D-49
-------
Proposed Western Alkaline Coal Mining Subcategory
Null
Null
**
Null
#£>
Null
Structure Routing Details:
^ Land RowCcxKJition
#1 9. Small streams flowing bankfull
#1 Muskingum K:
#2 9. Small streams flowing bankful!
#2 Muskingum K:
#3 • 9. Small streams flowing bankfull
#3 Muskingum K:
#4 9. Small streams flowing bankfull
#4 Muskingum K:
#5 9. Smalt streams flowing bankfull
its Muskingum K:
#6 9. Small streams flowing bankfull
#6 Muikingum K:
#7 9. Small streams flowing bankfull
#7 Muskingum K:
-#8 9. Small streams.flowing bankfull
4»8 Muskingum K:
^10 g. small streams flowing bankfull
«1O Muskingum K:
#11 9. Small streams flowing bankfull
#11 Muskingum K:
#12 9. Small streams flowing bankfull
#12 Muskingum K:
#13. 9. Small streams flowing bankfull
if 13 Muskingum 1C
#14 9. Small streams flowing bankfull
#14 Muskingum K:
#15 9. Small streams flowing bankfull
#15 Huskingum K:
Slope (%)
1.30
1.60
1.47
2.38
0.83
1.27
0.95
0.53
2.66
1.58
2.80
2.79
. 2.52
2.82
VertDist
(ft)
24.00
12.00
17.00
14.00
14.00
11.00
18.00
6.00
38.00
49.00'
45.00
30.00
50.00
79.00
Horiz-Dist
(ft)
1^47.57
75135
1,153.01
587.93
1,686.68
866.89
1,900.33
1,139.38
1,428.73
3,097.14
1,609.09
1,076.50
1,981.84
2,798.44
Velocity
(fps)
10.25
11.37
10.92
13.88
8.19
10.13
8.75
6.53
14.67
11.32
15.05
15.02
14.29
15.12
Time (his)
0.050
O.O5O
0.018
O.O18
. 0.029
0.029
0.011
. 0.011
0.057
O.O57
0.023
O.O23
0.060
O.O6O
0.048
O.O48
0.027
0.027
0.075
O.O75
0.029
O.O29
0.019
O.O19
0.038
0.038
0.051
O.051
Appendix D
D-50
-------
Structure Summary:
Immediate
Contributing
Area
Total
Contributing
Area
Peak
Discharge
(cfs)
Total
Runoff
volume
Peak Peak
Sediment Sediment Settteable
Cone. Cone.
244.26
320.56
555.244 354.80
394.83
Appendix D
D-51
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
Subwatershed Hydrology Detail:
Stm SWS SWSArea
# (ac)
#15
#14
3.038
12.123
8.741-
10.010
33.912
22.100
10.547
13.248
12.053
116.019
MuskX
UHS
Peak
Discharge
#12
#10
#11
1
2
3
4
2
i
2
2
1
40.766
7.113
29.932
' 9.575
87.386
20.295
• 14.858
35.153
8.414
4 H.Sfe
3
4
5
I,
#1 1
5.500
14.513
6.443
8JL345
44.593
•> nm I'M
104.087
288.818
0.100
0.100
O.W7 .
0.085
0.020
0.017^
0.033
0.019
0.041
0.053
0.304
0.122
0.121
0.166
0.165
65.000
74.000
0.016
0.000
0.455
0.000
0.316
74.000
79.000
65.000
81.000
0.301
65.000
0.000
74.000
0.020
79.000
0.007
0.000
0.000
0.000
65.000
74.000
74.000
0.000
79.000
0.104
0.000
0.440
93.000
0.000
93.000
0.000
0.000
93.000
3.42
Runoff
Volume
(ac-ft)
0.287
0.50
4.01
0.086
0.190
0.218
7.52
10.53
0.43
4.07
0.54
1.89 ,
0.781
0.755
0.075
0.294
0.094
0.301
•» ->c n_ifi4
0.287
0.081
0.120
0.316
0.220
2.283
4.209
D-52
Appendix D
-------
-
Stni SWS SWSArea
* * (ac)
*2 1 70.798
2 8.314
3 75.341
2 524.616
#3 1 5.514
2 25.114 -
Time of
Cone
(hrs)
0.114
0.039
0.172
0.044
0.120
ti(j[jmeru LJO
MuskK
(hrs)
0.011
0.000
0.000
0.000
0.000
cument - fr
MuskX
0.451
0.000
0.000
0.000
0.000
oposed western Alkaline Coal Minii
Curve
. ,_ UHS
Number
74.000 M
79.000 M
Peak
Discharge
(eft)
21.15
3.96
91 .500 M 54.68
j 320.56
88.000 M j 4.81
93.000 M 29.43
2 556.244
#4 1 11.735
2 23.800
3 9.965 -
0.045
0.082
0.023
0.000
0.000
0.012
0.000
0.000
0.385
i
354.80
88.000 M 10.24
93.000 M j 25.82
74.000 M 2.98
2 601.744 '
#5 1 8.058
2 30.520
0.037
0.078
0.000
0.000
0.000
0.000-
394.83
91.500 M 8.45
74.000 M 9.12
2 727.708
#6 1 72.562
2 13.858
3 15.142
0.282
0.062
0.027
0.000
0.000
0.016
0.000
0.000
0.377
93.000 M
445.51
51.41
91.200 M 14.34
74.000 M 4.52
2 829.270
#7 • 1 5.974
2 4.650
3 35.792
0.100
0.100
0.052
0.000
0.000
0.000
0.000
0.000
0.000
493.50
74.000 M 1.78
88.000 M 4.06
74.000 ' M 10.69
2 991.705
#8 1 55.9QO
2 15.352
3 16.414
0.221
0.067
0.080
0.000
0.037
• o.ooo
0.000
0.411
0.000
91.900 M
522.07
39.48
74.000 M j 459
88.000 M
2 1,079.371
#9 1 51.950
2 23.290
0.081
0.126
0.000
0.000
0.000
0.000
91.500 M
(98.000 M
2 1,188.523
14.32
555.78
54.54
13.55
601.89
Runoff
Volume
(ac-ft)
1.541
0.284
6.433
37.800
.0.371
2.465
40.636
0.789
2.246
0.217
43.888
0.688
0.664
47.662
6.849
1.160
0.330
55.999
0.130
0.313
0.779
59.807
4.903
0.334
1.104
66.148
4.435
1366
7Z930
got
1
•
Subwatershed Sedimentoiogy Detail:
Appendix D
D-53
-------
::,„
-'"'
;
"iiiii
*;
smi sws gg-j K
9 *
#15 1 0.370
2 0.150
3 0.240
4 0.240
2
#13 1 0.240
2 0.150
3 0.290
4 0150
5 0.240
6 0.240
2
#14 1 0.240
2 0.240
3 0.240
L(ft) S
100.00
450.00
450.00
475.00
500.00
250.00
100.00
450.00
250.00
275.00
375.00
385.00
375.00
(%)
650
6.00
6.00
9.00
5.00
6.00
6.40
5.00
5.00
9.00
6.60
8.00
530
C
0.4500
03100
0.1800
0.6300
0.4500
03100
0.4500
03100
0.3000
0.4500
05500
0.6300
0.4900
P PS*
l.OQOO 1
0.4700 3
,.:.•::. ,| : -.
peak reaic
Sediment Sediment SettJeable
Cone Cone
(Kins)
(mg/l) (ml/I)
12 4 f 5*> 14.94
0.6
0.4500 4 1.9
0.4700 4 93
24J
-1.0000 2 | 45.2
0.4700 ' 3 ' 0.4
1.0000 2 |
0.4700 3
0.4500 4
0.4600 4
1U./
05
2i
5.2
64.2
0.4700 4 12.4
0.4700 4 j 7.7
0.6300 4
2
#12 1 0.260
2 0.150
3 0.240
4 0.240
2
#10 1 0.290
2 0.250
- 2
#11 1 0.290
2 0.150
3 0.240
4 0.240
5 0.240
2
#1 1 0.370
2 0.370
3 0.370
340.00
250.00
375.00
400.00
650.00
750.00
'250.00
500.00
450.00
475.00
400.00
650.00
800.00
850.00
730
6.00
5.50
6.40
7.00
350
11.00
6.00
6.00
5.00
2.60
450
3.00
250
0.4500
03100
0.4800
0.4500
0.4500
0.4500
•
0.4500
03100
0.0530
0.6300
0.4500
0.4500
0.4500
0.4500
1.0000 2
5.5
89.8
125.9
0.4700 3 0.2
. 05100 4 19.6
0.6900 4 . 83
154.0
1.0000 2 | 85.4
1.0000 2 . 115
; 96.9
1.0000 2 37.5
0:4700 3 05
0.4400 4
0.4500 4
1.0000 2
0.3
6.2
3.9
i 145.4
1.0000 1 452.3
1.0000 1
1.0000 1
2
$2 1 0.240
2 0.240
550.00
250.00
2.90
8.20
0.4900
0.4500
0.6300 4
633.3
391.6
.1,477.1
28.8
1.0000 -2 17.4
10,413
18,279
80383
56,094
93,826
7,641
6,567
13,681
55,978
73,318
61,717
46,217
38,327
98,626
126,187
7,290
53,055
69,563
99,183
168,832
40,689
142,562
195,593
10,885
5,005
35,604
28,804
121,806
137,017
78397
65,611
86,019
33,224
95332
7.70
12.77
52.56
.25.64
64.30
5.65
3682
4.85
8.80
39.11
50.27
43.12
28.60
2453
66.96
86.47
5.39
37.07
48.60
68.21
115.70
25.82
96.84
134.04
8.05
350
22.48-
19.74
82,73
35.57
11.44
9.57
15.54
23.21
65.67
24VW
(ml/1)
8.13
350
5.24
24.87
10.88
29.51
257
18 11
2.97
4.27
16.15
19.19
17.82
15.10
12.08
17.97
2.45
15.30
20.12
3O.77
54.71
13.02
40.22
62.46
3.66
1.43
11.38
8.97
33.13
19.65
6.17
5.1E
8J3
95!
30.1!
I
>
i
D-54
-------
Stru SWS , .. „
# # SoilK
3 0.355
2
#3 1 0.320
• 2 0.370
L(ft)
350.00
190.00
250.00
S(%)
7.00
10.00
8.00
C
0.4500
0.4500
0.4500
P PS*
1.0000 1
Sediment
(tons)
6443
2313.0
1.0000 1 ! 35.5
1.0000 1
2
*4 1 0.320
2 0.370
3 0.240
125.00
315.00
500.00
8.00
6.30
6.40
0.4500
0.4500
0.4500
1.0000 1
2665
2,615.0
47.7
1.0000 1 2145
0.6900 4
I
#5 1 0.320
2 0.240
225.00
320.00
7.50
8.00
0.4500
0.5100
1.0000 1
0.7200 4
2
#6 1 0.370
2 0.350
3 0.240
• 2
#7 1 0.240
2 0.320
3 0.240
360.00
275.00
500.00
300.00
300.00
525.00
8.30
7.10
6.00
5.40
5.40
3.80
0.4500
0.4500
0.4500
0.4500
0.4500
0.4700
1.0000 1
9.7
%88&8
50.0
39.7
3,130.5
820.0
1.0000 1 103.3
0.6900 4 w 5
4,068,0
0.6900 4
1.0000 1
0.6700 4.
2
*8 1 0.333
2 0.240
3 0.320
2
#9 1 0.365
2 0.320
2
440.00
375.00
600.00
375.00
375.00
870
7.20
6.40
7.00
7.00
0.4500
0.4500
0.4500
0.4500
0.4500
1.0000 1
3.6
"18.0
17.3
4,196.6
572.2
0.6900 4 15 2
1.0000 1 | 122.8
1.0000 1 ["
1.0000 1 i
— ^— -^— — —
— ^— — «_ •.
4,906.1
5560
124.8
5,611.1
Peak
Sediment
Cone
(mg/l)
159,109
103,515
128,519
137,773
102,682
82,584.,
122,434
77,880
101,460
95,476
103,274
10%214
188,469
116,261
77,023
111,723
48,834
78,755
39,426
108,988
184,917
79,460
147,976
115,962
160,140
129,681
114,800
Peak
SetHeable
Cone
(ml/I)
21.76
21.70
33.37
35.77
22.12
., 21.44
31.79
54.41
22.43
24.79
72.15
25.60
19.04
30.18
53.81
24.80
34.12
20.45
27.54
25.53
22.08
55.51
38.42
25^4
41.58
16.01
25.86
24VW
(ml/1)
11.83
10.80
17.62
19.77
1L53
11.26
17.54
22.55
11.94
13.49
30.04
1138
10.50
16.42
22.30
13.17
14.07
10.74
13.35
12.07
23.02
20.33
13.44
22.77
8.56
13.96
Subwatershed Time of Concentration Details:
Stru
#
#1
SWS
9
1
Land How Condition
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
-' •—^••i— •,
Slope (%)
4.71
3.49
VertDist
(ft)
•
30.00-
5J'.00
Horiz-Dist.
(ft)
636.28
1,634.92
Velocity
(fc*)
4.370
5.600
Time (hrs)
0.040
• 0.081
Appendix D
D-55
-------
iii.":1! , „• jif- !,,.;tl • •• -i . :'"; 1 , ,.'.,!
Development Document - Proposed Western Alkaline
„ i i. ' i. • if „ "i il " , • , „."' •
Coal Mining
sew SWS Land ROW condition Slope (%)
* *
#1 1 Time of Concentration:
7. Paved area and small upland
#1 z gullies
8. Large gullies, diversions, and tow
flowing streams
9. Small streams flowing bankfull
7. paved area and small upland
S1 f gullies
8. Large gullies, diversions, and low
flowing streams
#1 3 Thne of Concentration:
7. Paved area and small upland
*2 * gullies
9. Small streams flowing bankfull
#2 1 Time of Concentration:
" 7. Paved area and small upland
*2 2 gullies
9. Small streams flowing bankfull
#2 2 Time of Concentration:
7. Paved area and small upland
*2 3 gullies
8. Large gullies, diversions, and low
flowing streams
9. Small streams flowing bankfull
#2 3 Thne of Concentration:
7. Paved area and small upland
*3 x gullies
9. Small streams flowing bankfull
#3 1 Time of Concentration:
7. Paved area and small upland
*3 2 auMies
8. Large gullies, diversions, and low
1 flowino streams
#3 2 Thne of Concentration:
7. Paved area and small upland
9. Small streams flawing bankfull
#4 i Thne of Concentration:
^ 7. Paved area and small upland
*4 2 gullies
8. Large gullies, diversions, and low
flowing streams
#4 2 Thne of Concentration:
7. Paved area and small upland
*4 3 gullies
1 #4 3 Time of Concentration:
8.78
3.22
1 86
—
3.12
2.38
3.17
3.12
6.12
2.58
1.73
3.19
1.07
7.32
""~
1 fi1
2.34
3.72
9.60
2.29
4.66
4.06
9.00
Hit ••"';' , ' •(, » i •, '
Subcategory
rtDtst HoritDist.
(ft) (ft)
• — '
70.00 796.90
. — — —
29.00 901.45
69.00 3,706.88
38.00 1,216.03
28.00 1,177.90
40.00 1,262.82
32.00 . 1,025.90
30.00 490.00
17.00 660.01
14.00 807.05
29.00 908.12
15.00 ' 1,400.03
• „• • n 111
. ' \ .'• ' '•" ^ i:
velocity Time(hrs)
(fps;
a 121
5.960 0.037
5.380 0.046
12.270 0.083
0.166
3.550 0.095
4.620 0.070
O.165
1
3.580 0-097
15.890 0.017
O.114
4.980 0.027
14.440 0.012
OLO99
2,650 0.084
• 5.360 0.047
9.310 0.041
43.00 587.07 5.440 0.029
10 00 620.27 11.420 0.015 1
0.044'
15.00 . 640.64 3.080 0.057
49.00 1,318.19 5.780 0.063
O.12O
60.00 625.00 6.230 0.027
22.00 959.65 13.620 0.019
O.O45
14.00 300.11 4.340 0.019
56.00 1,378.22 6.040 • 0.063
aosz
45.00 499.99 6.030 0.023
O.O23
D-56
-------
Development Document-
.H Western Alkaline Coal Minin
Land Flow Condition
8. Large gullies, diversions, and low
. Small streams flowing bankfull
7. Paved area and small upland
gullies
9. Small streams flowing, bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
2 7. Paved area and small upland
gullies
• 9. Small streams flowing bankfull
Time of Concentration:
, 7. Paved area and small upland
gullies
Time of Concentration;
1 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration;
, 7. Paved area and small upland
gullies
9. Small streams flowing bankfull
3 Time of Concentration:
j • 7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
_
9. Small streams flowing bankfull
— " - - --
Time of Concentration;
, 7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams
75.00 900.00
8.00 1,051.00
9. Small streams flowing bankfull
Time of Concentration:
— • •• — -..
7. Paved area and-small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
Appendix D
D-57
-------
II
,'K!'!!"
Dev
•:
iFXrii
1 li i.
[•
"!'i i]"!'ll' '
'•iii'i •;
•ii'iiA,, ' "a
.. , , ' ,"'» :• is • . ,-' ! ' ,
dopment Document - Proposed Western Alka_
Stru SWS
# #
*9 1
_...
#9 1
#9 2
#9 2
#10 1
#10 1
#10 2
#1O 2
#11 1
#11 1
«n z
#11 2
#11 3
#11 3
#11 4
1
#11 4
#11 5
#11 5
#12 4
#12 4
#13 1
Land Row Condition
7. Paved area and small upland
jiu'ltes
9. Small streams flowing bankftill
Time of Concentration:
7. Paved area and small upland
gullies
8. Large gullies, diversions, and low
flowing streams " .
9. Small streams flowing bankfiill
. • — ~
Time of Concentration:
7. Paved area and small upland
gullies
8. Large-gullies, diversions, and taw
flowing streams
Thne of Concentration:
7. Paved area and small upland
gullies
6. Grassed waterway
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Tone of Concentration:
7. Paved area and small upland
gullies '
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
6. Grassed waterway
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration: '
7. Paved area and small upland
guHies
6. Grassed waterway
Time of Concentration:
7. Paved area and small upland
gullies
'ine Coal Mining
' Subcategqry
«>,•. Vert DSL Horiz-Dist.
Slope (%) (ft) ((t)
7.32
"—
2.60
— — •' '
•
3.64
3.64
__ — — — — — —
1.91
8.23
5.22
3.74
1.00
9.62
4is3
6.00
""•
1.77
4.93
1.39
3.21
1.00
3.71
1.00
7.30
1.00.
4.96
45.00
69.00
42.00
26.00
8.00
73.00
30.00
39.00
8.82
25.00 .
26.00
30.00
10.00
37.00
4.00
39.00
11.40
45.00
11.40
49.00
2.50
30.00
615.00
2,650.07
1,154.32
714.95
418.23
887.11
575.14
1,044.12
882.00
"•!• ,
.. i':'; ':'.*
V?^ Time(hrs)
(fps)
5.440
14.520
— . —
" ' ""
3.830
5.720
12.440
5.770
6.850
3.890
1.500
260.00 6.240
573.95 19.150
_ — —
500.00 4.930
566.34 11.950
750.00 4.470
288.43 10.590
1,214.57 3.600
1,140.00 1.500
1,214.54 3.870
1,140.00 9.000
670.79 5.440
250.00 1.500
605.00 4.480
0.031
0.050
O.O81
0.083
0.034
0.009
a 126
0.042
0.023
0.065
0.074
0.163
0.237
0.01-1
0.008
0.028
0.013
O.O41
0.046
0.007
O.053
0.093
0.211
0.304
0.087
0.035
aisa
0.03'
0.04(
aow
0.0?
»
>
7
D-58
Appendix D
-------
Stru SWS
# « Land Row Condition
Slope (%)
——————.———__^^_^_____
8. Large gullies, diversions, and low
Velocity
Ops)
Time (hrs)
nowing streams *»*• »-uo 997.22 5.690 0.048
#13
#13
#13
#13
#13
1
2
2
3
3
Time of Concentration:
7. Paved area and small upland
gullies
9. Small streams flowing bankfull
Time of Concentration:
7. Paved area and small upland
gullies
Time of Concentration:
.
0.085
.
6.00 15.00 250.00 4.930 0.014
5.88 30.00 510.00 21.820 0.006
0.020
4.00 10.00 250.00 4.020 0.017
aoi7|
4 gullies
4.08
20.00
490.00
500.00
4.060
Subwatershed Muskingum Routing Details:
# # Land How Condition
0.033
O.O33
4.220
1.500
0.032
0.199
0.231
Time of Concentration:
5 7. Paved area and small upland
gullies
6. Grassed waterway
10.77 1.077.00
Time of Concentration:
6 7. Paved area and small upland
gullies
6. Grassed waterway
6 Time of Concentration:
, 7. Paved area and small upland
gullies
35.00 625.00
Time of Concentration:
7. Paved area and small upland
gullies
6. Grassed waterway
20.16 2,016.00
Time of Concentration:
6. Grassed waterway
1.3.53 1,353.00
Time of Concentration:
7. Paved area and small upland
gullies
10.67 40.00 375.00
1.00 7.14 715.00
6. Grassed waterway
Time of Concentration:
— ' ™—^—«•
9. Small streams flowing bankfull
9. Small streams flowing bankfull
—
3 7. Paved area and small upland
mi Mine
Appendix D
D-59
-------
pment Document - Proposed Western Alkaline Coal Mining Subcatego
Horiz.Dist Velocity Time(hrs)
(ft) (ft*)
0.012
Land Flow Condition
MMfcingumK:
7. Paved area and small upland
gullies
Huridngum K:
9. Small streams Bowing banMull
MmkingumK:
9. small streams flowing banMull
HmldnginnK;
9. Small streams flowing banknill
Husking"" K:
9. Small streams ftowing banktull
Muriangian 1C
7. Paved area and small upland
gullies
6. Grassed waterway
Husldngum K;
7. Paved area and small upland
gullies
6. Grassed waterway
8.00 1,061.00
14.00 854.80
_
4.00 288.43
"•' !„; • t
D-60
Appendix D
-------
L
Elevation
4,616.50
4,617.00
4,617.50
4,618.00
4,618.50
4,619.00
4,619.50
4,620.00
4,620.50
4,621.00
4,621.50
4,621.58
4,622.00
4,622.50
4,623.00
4,623.50
4,624.00
4,624.50
4,625.00
4,625.50
4,626.00
4,626.50
4,627.00
4,627.50
4,628.00
4,628.50
4,629.00
4,629.50
4,630.00
4,630.50
4,631.00
4,631.50
4,632.00
4,632.50
4,633.00
4,633.50
4,634.00
4,634.50
4,635.00
4,635.50
4,636.00
Area
(ac)
5.671
6.216
6.784
7.378
7.996
8.639
9.307
10.000
10.122
10.246
10.369
10.389
10.494
10.619
10.746
10.872
11.000
11.128
11.257
11.387
11.518
11.649
11.781
11.914
12.047
12.182
12.317
12.453
12.589
12.726
12.864
13.003
13.143
13.283
13.424
13.566
13.708
13.851
13.995
14.140
14.285
,vKiufjrneru L>(
Capacity
(ac-ft)
16.855
19.825
23.074
26.613
30.456
34.613
39.099
43.924
48.955
54.047
59.201
59.987
64.417
69.695
75.036
80.441
85.909
91.441
97.037
102.698
108.424
114.216
120.073
125.997
131.987
138.045
144.169
150.362
156.622
162.951
169.349
175.815
182.352
188.958
195.635
202.382
209.201
216.090
223.052
230.086
237.192
icument - Proposed Western Alkaline Coal Mining Subca
Discharge Dewater
Time
(hrs)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0-000 Spillway #1
5.419 11.51*
15.354 1.30 Peak Stage
71.329
145.356
241.897
356.760
489.149
638.637
805.005
988.163
1,188.108
1,404.895
1,638.623
1,889.420
2,157.436
2,442.839
2,745.811
3,066.542
3,405.229
3,762.076
4,137.291
4,531.083
4,943.667
5,375.254
5,826.061
6,296.302
6,786.193
7,295.949
7,825.783
8,375.908
8,946.538
fegi
— i
D-61
-------
Development Document - Proposed Western Alkaline Coal Mining Subcategory
file average inuil sediment yield numbers presented in Table 6b, in Section 6, were calculated
by using the pond design feature in SEDCAD 4.0. By putting a fictitious pond at the bottom of
the model SEDCAD wiU calculate the amount of sediment storage needed to store the sediment
yield. The fictitious pond structure details along with the estimate of the sediment storage is
presented on the following pages.
Structure Detail:
Structure #16 fPond)
Pond Inputs:
Initial Pool Bev:
4,611.68
Initial Pool:
0.00 ac-ft
*Sediment Storage:
6.64 ac-ft
Dead Space:
20.00 %
*Sediment capacity based on Average Annual R of3O.O for 1 year(s)
Spillway Hev
4,621.00
Crest Length
(ft)
20.00
Left
-Sidesiope
2.00:1
Right
Sidesiope
2.00:1
Bottom
Width (ft)
30.00
Pond Results:
Peak Elevation:
4,621.58
H'graph Detention Time:
13.67 hrs
Pond Model:
csres
DewaterTime:
0.53 days
Trap Efficiency:
100.00 %
Dewatering time is calculated frvm peak stage to lowest spillway
Elevation-f-apacftv-biseharae Table
D-62
.IP <
" ••!
Elevation
4,611.68
4,611.68
4,612.00
4,612.50
4,613.00
4,61350
4,614.00
4,614.50
4,615.00
4,615.50
4,616.00
Area
(ac)
1.706
1.706
1.898
2.218
2.563
2.932
3.327
3.746
4.190
4.659
5.153
Capacity
(ac-ft)
0.000
0.002
0.579
1.606
2.800
4.173
5.737
7.504
9.486
11.698
14.149
~, i- Dewater
Discharge ^^
<•<& (hrs)
0.000 Top of Sed. Storage
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
I ' ' III"! 1 I1, , ' ' ' i
Appt
" i', J i,!f
mdix D
-------
Elevation
4,636.50
4,637.00
4,637.50
4,638.00
4,638.50
4,639.00
4,639.50
4,640.00
4,640.50
4,641.00
4,641.50
4,642.00
4,642.50
4,643.00
4,643.50
4,644.00
4,644.50
4,645.00
4,645.50
4,646.00
4,646.50
4,647.00
4,647.50
4,648.00
4,648.50
4,649.00
4,649.50
4,650.00
4,650.50
4,651.00
4,651.50
4,652.00
4,652.50
4,653.00
4,653.50
4,654.00
4,654.50
4,655.00
4,655.50
4,656.00
4,656.50
Area
(ac)
14.432
. 14.579
14.726
14.875
15.024
15.174
15.324
15.476
15.628
15.781
15.935
16.089
16.244
16.400
16.557
16.714
16.872
17.031
17.190
17.351
17.512
17.674
17.836
18.000
18.164
18.328
18.494
18.660
18.827
18.995
19.164
19.333
19.503
19.674
19.845
20.017
20.190
20.364
20.539
20.714
20.890
wveiopmem Document - Proposed Western Alkaline Coal Mining Subcate
Capacity Discharge Deyrater
Time
244.371 9,537.884
251.624 10,150.150
258.950 10,783.560
266.350 11,438.300
273.825 12,114.600
281.374 12,812.640
288.999 13,532.630
296.699 14,274.780
304.475 15,039.290
312.327 15,826.340
320.256 16,636.150
328.261 17,468.890
336.345 18,324.770
. 344.506 19,203.970
352.745 20,106.690
361.062 21,033.100
369.459 21,983.410
377.934 22,957.790
386.490 23,956.420
395.125 24,979.490
403.841 26,027.170
412.637 27,099.650
421.514 28,197.100
430.473 29,319.690
439.514 30,467.600
448.637 31,640.990
457.843 32,840.050
467.131 34,064.930
476.503 35,315.820
485.959 36,592.860
495.498 37,896.230
505.122 39,226.080
514.831 40,582.590
524.625 41,965.910
534.505 43,376.200
544.471 44,813.610
554.523 46,278.320
564.661 47,770.450
574.887 49,290.190
585.200 50,837.670
595.601 52,413.040
D-63
-------
•velopment Document - rroposea western tuw.™^ ^^^ ^^^y, ?--^ — __ _
••
,i,j'"' , i
*
.
>r: „«
I"1 ' • , • 'Nil
'"Hi!'1 i , ' , " , ' ;"
" , , " 'I* '
r •. '
Elevation
4,657.00
4,65750
4,658.00
4,65850
4,659.00
4,65950
4,660.00
4,66050
4,661.00
4,66150
4,662.00
4,66250
4,663.00
4,66350
4,664.00
4,66450
4,665.00
4,66550
4,666.00
4,66650
4,667.00
4,66750
4,668.00
4,66850
4,669.00
4,669.50
4,670.00
4,67050
4,671.00
4,671.50
4,672.00
4,67250
4,673.00
4,67350
4,674.00
4,67450
4,675.00
4,67550
4,676.00
4,67650
4,677.00
D-64
Area
(ac)
21.067 "
21.244
21.422
21.601
21.781
21.961
22.143
22324
22.507
22.691
22.875
23.060
23.245
23.432
23.619
23.807
23.995
24.185
24.375
24.566
24.757
24.950
25.143
25336
25.531
25.726
25.922
26.119
26.317
26.515
26.714
26.914
27.114
27.316
27.518
27.721
27.924
28.128
28.333
28.539
28.746
Capacity
(ac-ft)
606.090
616.668
627.334
638.090
648.935
659.871
670.897
682.014
693.222
704.521
715.912
727.396
738.972
750.641
762.404
774.260
786.210
798.255
810.395
822.630
834.961
847.388
859.911
872.530
885.247
898.061
910.974
923.984
937.093
950.301
963.608
977.015
990522
1004.130
1017.838
1031.647
1045559
1059.572
1073.687
1087.905
1102.226
_. . Dewater
Discharge T,me
WS> (hrs)
54,016.470
55,648.090
57308.060
58,996510
60,713.600
62,459.480
64,234.280
66,038.150
67,871.220
69,733.650
71,625560
73,547.090
75,498.400
77,479.600
79,490.840
81532.250
83,603.950
85,706.100
87,838.810
90,002.230
92,196.470
94,421.660
96,677.950
98,965.440
101,284300
103,634.600
106,016500
108,430.100
110,875.500
113352.900
115,862.400
118,404.000
120,978.100
123584.500
126,223.500
128,895.200
131599.700
134337.100
137,107500
139,911.100
142,748.000
, ,. , , • , • . , , -
Appendix D
-------
Development Document - Proposed Western Alkaline Coal Mining Subcateeor
Elevafion
4,624.00
4,624.50
4,625.00
4,625.50
4,626.00
4,62650
4,627.00
4,627.50
4,628.00
4,628.50
4,629.00
4,629.50
4;630.00
4,630.50
4,631.00
4,631:50
4,632.00
4,632.50
4,633.00
4,63350
4,634.00
4,634.50
4,635.00
4,635.50
4,636.00
4,636.50
4,637.00
4,637.50
4,638.00
4,638.50
4,639.00
4,639.50
4,640.00
4,640.50
4,641.00
4,641.50
4,642.00
4,642:50
4,643.00
Emergency
Spillway (cfe)
489.149
638.637
805.005
988.163
1,188.108
1,404.895
1,638.623
1,889.420
2,157.436
2,442.839
2,745.811
3,066.542
3,405.229
3,762.076
4,137.291
4531.083
4,943.667
5,375.254
5,826.061
6,296302
6,786.193
7,295.949
7,825.783
8,375.908
8,946.538
9,537.884
10,150.150
10,783.560
11,438.300
12,114.600
12,812.640
13532.630
14,274.780
15,039.290
15,826.340
16,636.150
17,468.890
18324.770
19,203.970
-r Combined
Total
Discharge
(cfe)
489.149
S38.637
805.005
988.163
1,188.108
1,404.895
1,638.623
1,889.420
2,157.436
2,442.839
2,745.811
3,066.542
3,405.229
3,762.076
4,137.291
4531.083
4,943.667
5375.254
5,826.061
6,296.302
6,786.193
7,295.949
7,825.783
8375.908
8,946538
9537.884
10,150.150
10,783560
11,438.300
12,114.600
12,812.640
13532.630
14,274.780
15,039.290
15,826.340
16,636.150
17,468.890
18324.770
19,203.970
Appendix D
D-65
-------
. : '
'.'. " ' , """"' ,:;
•• '•'
%
iV " '• S,:!h "!"!
»i'!" , '„: !l ,' i'f, ,i
!„ ' i: «'•; !
. i:,,! . li,;1'
'!'', ' i ' J: Ti i ' , f !
Elevation
4,643.50
4,644.00
4,64450
4,645.00
4,64550
4,646.00
4,646.50
4,647.00
4,647.50
4,648.00
4,648.50
4,649.00
4;S4950
4,650.00
4,65050
4,651.00
4,651.50
4,652.00
4,652.50
4,653.00
4,65350
4,654.00
4,65450
4,655.00
4,65550
4,656.00
4,656.50
4,657.00
4,65750
4,658.00
4,65850
4,659.00
4,65950
4,660.00
4,66050
4,661.00
4,66150
4,662.00
4,66250
Emergency
Spillway (ds)
20,106.690
21,033.100
21,983.410
22,957.790
23,956.420
24,979.490
26,027.170
27,099.650
28,197.100
29,319.690
30,467.600
31,640.990
32,840.050
34,064.930
35,315.820
36592.860
37,896.230
39,226.080
40582590
41,965.910
43,376.200
44,813.610
46,278.320
47,770.450
49,290.190
50,837.670
52,413.040
54,016.470
55,648.090
57,308.060
58,996.510
60,713.600
62,459.480
64,234.280
66,038.150
67,871.220
69,733.650
71,625.560
73547.090
Combined
Totel
Discharge
(crs)
20,106.690
21/333.100
21,983.410
22,957.790
23,956.420
24,979.490
26,027.170
27,099.650
28,197.100
29,319.690
30,467.600
31,640.990
32,840.050
34,064.930
35,315.820
36592.860
37,896.230
39,226.080
40582590
41,965.910
43,376.200
44,813.610
46^78.320
47,770.450
49^90.190
50,837.670
52,413.040
54,016.470
55,648.090
57^08.060
58,996510
60,713.600
62,459.480
64,234.280
66,038.150
67,871.220
69,733.650
71,625560
73,547.090
Appendix D
in i inii i i Hi
------- |