United States
           Environmental Protection
           Agency
           Environmental Monitoring
           and Support Laboratory
           P.O Box 15027
           Las Vegas NV 89114
EPA-600/7-79-024
January, 1979

           Research and Development
xvEPA
Groundwater Quality
Monitoring of Western
Coal Strip Mining:

Identification and
Priority Ranking  of
Potential Pollution Sources

Interagency
Energy-Environment
Research
and Development
Program Report

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                   RESEARCH REPORTING  SERIES

 Research reports of the  Office of Research and Development, U.S. Environmental
 Protection Agency, have been grouped into nine series. These nine broad categories
 were established to facilitate further development and application of environmental
 technology.  Elimination  of traditional grouping was consciously planned to foster
 technology transfer and a maximum interface in related fields. The nine series are:

       1.  Environmental Health Effects Research
       2.  Environmental Protection Technology
       3.  Ecological Research
       4.  Environmental Monitoring
       5.  Socioeconomic Environmental Studies
       6.  Scientific and Technical Assessment Reports (STAR)
       7.  Interagency Energy-Environment Research and Development
       8.  "Special" Reports
       9.  Miscellaneous Reports


 This  report  has  been assigned  to the  INTERAGENCY ENERGY—ENVIRONMENT
 RESEARCH AND  DEVELOPMENT series.  Reports in this series result from the effort
 funded under the 17-agency Federal Energy/Environment Research and Development
 Program.  These studies relate to EPA'S mission to protect the public health and welfare
 from adverse effects of pollutants associated with energy systems. The goal of the Pro-
 gram is to assure the rapid development of domestic energy supplies in  an environ-
 mentally-compatible  manner by providing the necessary  environmental data and
 control technology. Investigations include analyses of the transport of energy-related
 pollutants and their health and ecological effects; assessments of, and development of,
 control technologies for energy systems; and integrated assessments of a wide range
 of energy-related environmental issues.
This document is available to the public through the National Technical Information
Service, Springfield, Virginia  22161

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                                                  EPA-600/7-79-024
                                                   January 1979
          GROUNDWATER QUALITY MONITORING
            OF WESTERN COAL STRIP MINING:
          Identification and Priority Ranking of Potential
                     Pollution Sources
                       Edited by
                     Lome G. Everett
             General Electric Company—TEMPO
                Center for Advanced Studies
               Santa Barbara, California 93102


                 Contract No. 68-03-2449
                      Project Officer
                    Leslie G. McMillion
     Monitoring Systems Research and Development Division
       Environmental Monitoring and Support Laboratory
                 Las Vegas, Nevada 89114

ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
        OFFICE OF RESEARCH AND DEVELOPMENT
       U.S. ENVIRONMENTAL PROTECTION AGENCY
               LAS VEGAS, NEVADA  89114

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                                 DISCLAIMER
     This report has been reviewed by the Environmental  Monitoring and Support
Laboratory-Las  Vegas, U.S. Environmental Protection Agency, and approved for
publication.  Approval  does not signify that the contents necessarily reflect
the views and policies  of the U.S. Environmental Protection Agency, nor does
mention of trade names  or commercial products constitute endorsement or recom-
mendation for use.

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                                  FOREWORD
     Protection of the environment requires effective regulatory actions
which are based on sound technical and scientific information.  This infor-
mation must include the quantitative description and linking of pollutant
sources, transport mechanisms, interactions, and resulting effects on man
and his environment.  Because of the complexities involved, assessment of
specific pollutants in the environment requires a total  systems approach
which transcends the media of air, water, and land.  The Environmental Moni-
toring and Support Laboratory-Las  Vegas  contributes  to  the  formation  and
enhancement of a sound monitoring data base for exposure assessment through
programs designed to:

     •  Develop and optimize systems and strategies for monitoring
        pollutants and their impact on the environment

     •  Demonstrate new monitoring systems and technologies by
        applying them to fulfill special monitoring needs of the
        Agency's operating programs.

     This report presents the initial phases of a study to design and imple-
ment groundwater quality monitoring programs for Western coal strip mining.
The development of a preliminary priority ranking of potential pollution
sources and the pollutants associated with these sources is presented.

     The results of this report are the initial segment of the design and
field implementation effort.  The priority ranking will  be combined in sub-
sequent study phases with evaluations of deficiencies in existing or proposed
monitoring efforts and alternative monitoring technologies to design a cost-
effective groundwater quality monitoring program.

     The research program, of which this report is part, is intended to pro-
vide basic technical information and a planning format for the design of
groundwater quality monitoring programs for Western coal strip mining opera-
tions.   As such, the study results may be used by coal developers and their
consultants, as well as the various local, State, and Federal agencies with
responsibilities in environmental monitoring and planning.
                                     ill

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     Further information on this study and the subject of groundwater
quality monitoring in general can be obtained by contacting the Monitoring
Systems Design and Analysis Staff, Environmental Monitoring and Support
Laboratory, U.S. Environmental Protection Agency, Las Vegas, Nevada.
                                          Georgjg Bi Morgan
                                              Director
                           Environmental Monitoring and Support Laboratory
                                             Las Vegas

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                                    PREFACE


     General Electric-TEMPO,  Center  for  Advanced  Studies,  is conducting a  5-
year program dealing with the design and implementation of an exemplary ground-
water quality monitoring program for Western coal  strip mining.  The coal  strip
mining activity discussed in this report is located in Campbell County, Wyoming.
In addition to mining impacts, the report discusses secondary water resource
impacts of municipal and industrial support programs which accompany the mining
effort.  The report follows a stepwise monitoring methodology developed by
TEMPO.

     This report represents the initial phase of this research program.  De-
scribed herein is the development of a preliminary priority ranking of potential
pollution sources and their associated pollutants.  This priority ranking will
be utilized in subsequent phases of the research as the basis for defining mon-
itoring needs and for ultimately designing the monitoring program.

     In the next phases of this research program,  a preliminary monitoring
design is to be developed and implemented in the field^  Initial field study
results may result in a reevaluation of the priority ranking presented in this
report.  The final product of the 5-year program will be a planning document
which will provide a technical basis and a methodology for the design of ground-
water quality monitoring programs for coal development companies and the various
governmental agencies concerned with environmental planning and protection.

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                                    SUMMARY


      General Electric-TEMPO has developed a methodology for designing ground-
 water quality monitoring programs.   This  was  a conceptual design which
 involved a series of data compilations  and  evaluation steps leading to a moni-
 toring system in place.  General  Electric-TEMPO is now applying that  method-
 ology to design a system to monitor the impact of  western coal  strip mining on
 groundwater quality.  This document reports the  field survey and literature
 research performed during the  first phase of  the design process.  The goal of
 this phase is to identify and  rank  the  major  sources of groundwater quality
 degradation.  The site for which  the monitoring  system is being designed
 follows the outcrop of the Fort Union Formation  in Campbell County, Wyoming.
 In addition to the City of Gillette, Wyoming, the  project area  includes the
 following mines:  Carter North Rawhide, AMAX  Eagle Butte, Wyodak, AMAX Belle
 Ayr, Sun Oil Cordero,  Kerr-McGee  Jacobs Ranch, and ARCO Black Thunder.

      The priority ranking is based  on a sequence of data compilation and
 evaluation steps.   These steps include  identification of potential pollution
 sources, methods of waste disposal,  and potential  pollutants associated with
 the various waste sources;  and an assessment  of  the potential for infiltra-
 tion and subsequent mobility of these pollutants in the subsurface.  The
 three basic criteria used to develop the  source-pollutant ranking are:

         •  Mass  of waste, persistence,  toxicity, and concentration

         •  Potential mobility

         •  Known or anticipated harm to water use.

      The  information base and  related assessments  utilized  to develop rank-
ings  based  on the  above methodology  are summarized in the main  body of this
report.

     Available background information and field  reconnaissance  were employed
to describe the  hydrogeology and water  quality of  the study area.  These data
were used in concert with the  source-pollutant characterization to assess  the
potential for pollutant mobility.

     Three major classifications of  potential pollution  sources have  been
inventoried:  Agricultural, Industrial, and Municipal.   Agricultural  sources
were found to be insignificant due to their diffuse nature.   Irrigated  farm-
land is practically nonexistent and  dryland farming, which  is economically
marginal, is the general  method.

     The  Industrial classification  includes Construction, Oil and Gas


                                      vi

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Extraction, Coal Strip Mining, and Coal Conversion activities.  Of these four,
coal strip mining and coal conversion are the most significant in terms of
potential groundwater quality degradation.  Almost all of the wastes associ-
ated with the construction industry are either disposed of in the Gillette
landfill, and as a result come under the Municipal wastes category, or are
disposed of with mine solid wastes on the leases.  The same can be said for
sanitary wastes from the construction industry where the City or mine dis-
posal facilities are utilized.

     The oil and gas extraction industry is probably a major potential ground-
water pollution source, however, it will not be investigated in a regional
sense in this study.  On mine leases where oil and gas wells exist or have
existed, potential groundwater impacts are of minor concern since they are few
in number and closely scrutinized because of their proximity to the mining
operations.

     Coal strip mining and its related sources have considerable potential to
produce groundwater quality degradation.  On the majority of mines, pollu-
tant source-specific monitoring does not eixst.  Where monitoring of sources
has been conducted it has not been source oriented but directed toward assess-
ing background quality levels, with the hope that eventually any changes in
quality due to pollutants will show up in the monitoring program.

     The above approach is the traditional approach utilized, but it is con-
trary to the objectives of Public Laws 92-500 and 93-523, which are aimed at
preventing, reducing, and eliminating groundwater quality degradation.  Once
pollutants show up in a background quality monitoring system, in many cases,
it is too late to institute controls.  Source monitoring is the key to deter-
mining which controls to implement and whether they are working.

     For active mining, the pit discharge represents a potential source of
groundwater pollution.  Much of the pit discharge is derived from native
groundwater; however, explosives, sewage effluents, spoils, coal, and other
sources can contribute pollutants.

     The relocation of spoils produces a changing chemical environment that
will be a permanent potential source.  Some groundwater will likely always
be in contact with the lower parts of the emplaced spoils.  Also, some stream-
flow will generally be rerouted, after mining, over the spoils along the
former floodplains and percolation will occur in some areas.  Holding ponds
placed on the spoils would be transitory in nature.  Groundwater contacting
the spoils will tend to occur indefinitely in specific parts of the reclaimed
areas.   In any area where groundwater was present in or above the coal seam
prior to mining, the spoils will generally be in contact with groundwater
after mining ceases.  Spoils placed below the water table have top priority
among mining sources for the following reasons:

        •  The soil and vadose zone are bypassed; thus there is no
           pollutant attenuation in these zones

        •  Generally, materials with the highest pollution potential
           are placed at the bottom of the spoils, and it is this


                                     vii

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           area that will be contacted by groundwater

        •  This source is permanent in a  sense and can  contribute
           pollutants over decades or centuries.

     Another priority for mining sources  would be for rerouted surface water
percolating into the spoils.  The extent  of this  problem depends largely on
the chemical nature and hydraulic head ultimately established in the spoils
and underlying materials and the permeability of  spoils beneath the stream
channel.  This source will also be permanent and  can contribute pollutants
for many decades or centuries after mining ceases.  A third priority for
mining sources would be percolation of streamflow below points of pit dis-
charge.  The extent of this problem is presently  poorly known due to a lack
of adequate monitoring of pit discharge.   Dilution due  to mixing with surface
water from natural runoff would limit the potential groundwater pollution.

     The quality of surface water can also be adversely impacted because in
some parts of the leases the groundwater  contributes to surface water flow.
Over the long term, substantial increases in the  salinity of surface water
could occur.  This, in turn, could exert  profound adverse impacts on down-
stream users of surface water.

     Of the three coal conversion activities projected  to be implemented in
the project area, steam electric power generation, gasification, and liquifi-
cation, only steam electric power generation is being implemented on a large
scale.  This plant is located on the Wyodak lease and most of its waste pro-
ducts will be disposed of in the mine pits.  The  primary waste will  be fly
ash, which will be disposed of both in ponds and  as landfill.   Secondary
wastes, e.g., sewage effluent and sludge, will  also be  disposed of in ponds
or as landfill.

     Top priority should be given to fly  ash landfill disposal in the pit at
levels which will lie below groundwater level. This top priority is based on:

        •  The disposal is basically permanent, and pollutants can
           be produced for decades or centuries

        •  Certain trace elements may well qualify fly  ash as a
           hazardous waste

        •  The soil and vadose zone are bypassed  and thus pollutant
           attenuation in these zones will not occur

        •  Large volumes of fly ash will  be disposed of.

     Second priority should be given to-the fly ash slurry pond.  This prior-
ity is based on:

        •  The wastewater disposed to this pond presents a ready
           source of water for leaching pollutants to the groundwater

        •  This source contains a variety of pollutants, including

                                     vi i i

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           salinity from brine disposal  and metals from the fly
           ash.

     Third priority should be given to fly ash landfilled above the water
table and beneath rerouted streams.  This priority is based on:

        •  A ready source of water is available for leaching

        •  The fly ash may well qualify as a hazardous waste.

     The principal potential municipal sources of groundwater  pollution are
the landfill, sewage treatment plant, and water treatment plant.   Only limit-
ed monitoring has been done on the landfill, sewage treatment  plant, or water
treatment plant.  Individual wells within the City's well field are subject
to damage from any of these three sources and, in the long term,  from the
mining operations.

     The complete priority ranking is shown in Table 1.  A great deal  of
effort has been expended on the study of the hydrogeology of the study area
and a large amount of research has been conducted on coal strip mine develop-
ment and environmental effects.  However, significant information voids exist
with regard to potential pollutant characterization and the mobility of these
materials in the hydrosphere.  Hence, professional judgment plays a large
role in proposing this preliminary source-pollutant ranking.

     This ranking will serve as the basis for the design of a  monitoring plan
for western coal strip mine development.  The next phase of the design pro-
gram includes evaluation of existing monitoring programs, identification of
alternative monitoring approaches to address the source-pollutant ranking,
and selection of a monitoring program for field implementation.  This  imple-
mentation will be used to verify (and quite probably revise) the  preliminary
ranking provided here.
                                     IX

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           TABLE 1.  PROJECT AREA POTENTIAL  POLLUTION SOURCE PRIORITY RANKING BY MAJOR CATEGORY
Coal strip mining
        Coal  conversion
           Municipal
1.  Spoils (below water table)
2.  Spoils (above water table
      below ponds or streams)
3.  Pit discharge (to streams)
1.   Fly ash (below  water  table)
2.   Fly ash slurry  pond
3.   Fly ash solids  (above water
      table)
1.  Hazardous wastes at landfill
2.  Disposal  well  water treatment
      plant
3.  Oily waste ponds at landfill
4.  Garbage trench at landfill
5.  Sewage effluent to Donkey Creek

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                                   CONTENTS


Foreword                                                              i i i
Preface                                                                 v
Summary                                                                vi
Figures                                                              xiii
Tables                                                                xvi
List of Abbreviations                                                  xx
Acknowledgments                                                      xxii
Section
   1     Introduction                                                   1
              Criteria for selecting the monitoring area                2
              Selection of the project area                             3
              Implementation of the priority ranking scheme             5

   2     Potential Sources of Pollution and Methods of Disposal         7
              Agriculture                                               7
              Industry                                                  8
              Oil and gas extraction                                   15
              Construction                                             15
              Coal conversion                                          18
              Municipal sources of pollution                           24

   3     Potential Pollutants                                          30
              Agriculture                                              30
              Coal strip mining                                        30
              Oil and gas extraction                                   54
              Construction                                             54
              Coal conversion                                         , 56
              Municipal                                                62

   4     Groundwater Usage                                             74
              Municipal usage                                          74
              Rural domestic usage                                     75
              Industrial usage                                         76
              Agricultural usage                                       77

   5     Hydrogeologic Framework                                       78
              Surface water hydrology                                  78
              Soils                                                    94
              Geology                                                 106
              Hydrogeology                                            110
              Modified hydrogeology                                   155
                                    XI

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  6     Existing Groundwater Quality                                 164
             Regional                                                164
             Municipal                                               184

  7     Infiltration  Potential                                       191
             Coal strip mining                                       191
             Coal conversion                                         194
             Municipal sources                                       194

  8     Pollutant Mobility  in the  Vadose  Zone                        198
             Coal strip mining                                       198
             Coal conversion                                         202
             Municipal                                               203

   9      Pollutant Mobility  in the  Saturated  Zone                     214
             Coal strip mining                                       214
             Coal conversion                                         216
             Municipal sources                                       217

  10     Priority Ranking  of Potential  Groundwater Pollution
         Sources                                                     222
             Agricultural activities                                 222
              Industrial                                              222
             Municipal                                               226

References                                                           229
Appendix A                                                           237
                                   xn

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                                   FIGURES

Number                                                                   Page
1-1    Major coal fields of Wyoming                                         4
2-1    Oil and gas fields associated with the Eastern Powder River
       Basin, Wyoming                                                      16
2-2    Hole bottom locations (Hoe Creek Experiment No. 1)                  22
2-3    Comparison of measured and calculated water production rates
       for the Hoe Creek Experiment No. 1 site                             23
2-4    Water levels at several locations within the fracture zone          23
2-5    Plan view of the packed-bed experiment                              24
5-1    Watershed map                                                       80
5-2    Physiographic divisions and drainage of Campbell County, Wyo.       81
5-3    Flow duration curves for selected Wyoming streams                   84
5-4    Relations for estimating flow characteristics in region 2 by
       using drainage area                                                 85
5-5    Relations for estimating flow characteristics in region 3 by
       using drainage area                                                 86
5-6    Hydrologic regions at monitoring area                               87
5-7    Surface water quality measurement sites                             88
5-8    Block diagram showing positions of some major kinds of aridisols
       and their associates                                                99
5-9    Soil associations of Campbell County, Wyoming                      100
5-10   Generalized map showing the Powder River Basin in relation to
       nearby structural features                                         107
5-11   Correlation of coal  beds in the Powder River Coal Basin            109
5-12   Aquifer relationships                                              111
                                    xi i i

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Number
5-13   Plots of results from four pump tests near Belle Ayr Mine          116
5-14   Isopach map of unconsolidated deposits along Cabal lo Creek         118
5-1 5   Hydrographs of three wells                                         119
5-16   Water level fluctuations in well N-3, April 26 - July 1, 1974      120
5-17   Water level fluctuations in well 481, May 10 - July 4, 1974        121
5-18   Geologic cross section from the center of the east line,
       section 22, to the NE corner, SE%, NE%, section 27, T5IN, R72W     125
5-19   Geologic cross section along west side of section 21, T51N,
       R72W                                                               126
5-20   Monthly water level elevations in instrumented monitor wells        130
5-21   Monthly water level elevations in instrumented monitor wells        131
5-22   Potenti ometric surface map, ARCO Black Thunder Lease               135
5-23   Groundwater flow in Roland aquifer                                 136
5-24   Monitor well locations, ARCO Black Thunder Lease                   137
5-25   Kerr-McGee Jacobs Ranch mine, Thunder Creek area                   145
5-26   Kerr-McGee Jacobs Ranch mine cross section K-K                     147
5-27   Static water levels- Jacobs Ranch mine                             148
5-28   Static water levels- Jacobs Ranch mine                             149
5-29   Kerr-McGee Jacobs Ranch mine well locations                         150
5-30   Water levels of monitor holes at Sun Oil Cordero mine               153
5-31   Idealized east-west cross section of Wyodak site                    154
5-32   Contours of water table, Wyodak area                                156
5-33   Effect of 50 years of mining in Wyodak north pit upon               157
       water table
5-34   Locations of monitoring wells, Wyodak mine                          158
6-1    Groundwater gaging network at the Black Thunder Site                178
                                    xiv

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Number                                                                  Page


8-1    Mobility of copper, lead, beryllium, zinc, cadmium,  nickel,
       and mercury through 10 soils series                              205

8-2    Mobility of selenium,  vanadium,  arsenic,  and  chromium through
       10 soils series                                                  205
                                     xv

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                                    TABLES
Number                                                                   Page
2-1    Other  Municipalities                                                28
3-1    Site-specific  Topsoil  Characteristics                               31
3-2    Concentrations of Trace  Elements Boron, Cadmium, Lead,
       and  Mercury in Soils  on  the Eagle Butte Mine Property               31
3-3    Site-specific  Overburden Characteristics                            33
3-4    Sulfur and Trace Element Concentrations in Coal Samples             35
3-5    Hypothetical  Quality  of  Wastewater  from the Gillette
       Treatment Plant                                                    37
3-6    Representative Septic Tank Effluent Concentrations  and
       Percent Removed                                                    39
3-7    Aerobic Tank Effluent Concentrations                               40
3-8    Range of Chemical Composition of Sanitary Landfill  Leachate         43
3-9    A Sample List of Nonradioactive Hazardous Compounds                45
3-10  Chemical Analysis of Incinerator Fly Ash                           46
3-11   Chemical Analysis of Incinerator Fly Ash                           47
3-12   Incinerator Residues                                                47
3-13   Incinerator Wastewater Data                                         48
3-14  Chemical and Physical  Data:  Three  Overburden Grab Samples           50
3-15  Trace Element Content of Coal and Associated  Rocks,
       Core BT249                                                          52
3-16  Comparison of Average Trace Element Concentrations (ppm)             53
3-17  Analyses of Overburden Materials                                    55
                                      xvi

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Number                                                                    Page
3-18
  (a)  Predicted Operating Conditions and Emissions from Unit 5 and
       the New Plant Under 100 Percent Load                                 57
  (b)  Peak Ground Level Contaminants from Existing Plant                   57
  (c)  Predicted Combined Ground Level Pollutant Concentrations from
       New Plant and Existing Unit 5                   .                    58
  (d)  Projected Constituents of Ash from the New Plant and Existing
       Unit 5                                                               58
3-19   Byproduct Water Analysts from Synthane Gasification of
       Various Coals                                                        60
3-20   Mass Spectrometrie Analysis of Benzene-Soluble Tars                  61
3-21   Hypothetical Quality of Wastewater, Gillette Treatment Plant         63
3-22   Septic Tank Septage Characteristics as Reported in the Literature    65
3-23   Typical Chemical Composition of Raw and Anaerobically Digested
       Sludge                                                               67
3-24   Metals in Sludge, 1971-1973                                          68
3-25   Analysis of Runoff Sample in Third Trench at the City of
       Gillette Landfill in June 1977                                       71
3-26   June 1977 Analysis of Water from Stone Pile Creek Behind
       Gillette Water Treatment Plant                                       72
3-27   Quantity and Characteristics of Contaminants in Urban Runoff         73
4-1    Major Mine Site Water Usage                                          76
5-1    Representative Chemical Measurements for Surface Water Quality       90
5-2    Drainage Areas for Lease Sites, Mean Annual Runoff, and
       25-Year Peak Discharge                                               95
5-3    Soil Series Classification of Campbell County                        98
5-4    Hydrologic Soil Classifications                                     105
5-5    Approximate Area! Percentages of Hydrologic Soil Groups             106
5-6    Aquifer Parameters in the Belle Ayr Mine Vicinity                   115
5-7    Well Completion Data, WRRI Groundwater Observation Wells,
       AMAX Belle Ayr South                                                122
                                     xvi i

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Number                                                                  Page
 5-8    Summary of Aquifer Test Data                                      I27
 5-9    Static Water  Levels Measured on Uninstrumented Wells              129
 5-10   Monitor Well  Inventory for AMAX's Eagle Butte Mine                132
 5-11   Calculated  Values of  Transmissivity and Storage Coefficient
        in Roland Formation                                               134
 5-12   Summary  of Elevation  of Water  Level in Roland Coal, Smith
        Coal, and Overburden  Compared  to Elevation of Top of Roland
        Coal and Smith Coal                                               138
 5-13   Inventory of Wells  and Springs, Rawhide Block Near Gillette,
        Wyoming                                                          140
 5-14   Summary of Aquifer  Test Data,  Kerr-McGee Jacobs Ranch Mine        146
 5-15   Description of Monitor Well Completions at Jacobs Ranch Mine      151
 5-16   Wyodak Groundwater  Monitoring  Stations                            159
 6-1    AMAX Belle  Ayr Water  Quality Data — Wasatch Formation Above
        the Coal                                                          166
 6-2    AMAX Belle  Ayr Water  Quality Data-Wyodak  Coal
                                                                         168
        AMAX Belle  Ayr Water  Quality Data-Scoria  Pit-Wasatch
 6-3    Formation Above the Coal                                          170
 6-4    AMAX Belle Ayr Water  Quality Data - Fort Union Formation Below
        Coal                                                              171
 6-5     Minimum and Maximum Values for Water Quality Parameters at
        AMAX  Eagle Butte Lease (all aquifers)                             173
6-6     Summary of Water Sampling Procedures During Tests of Various
        Wells at  the  Eagle Butte Mine                                     174
6-7     Results of Chemical  Analyses of Groundwater from Wasatch Wells    175
6-8     Results of Chemical  Analyses of Groundwater from Roland Coal
       Seam Waters                                                       176
6-9    Summary of Water Quality at Black Thunder Site Surface and
       Groundwater                                                       179
6-10   Water Quality Analyses of Water Wells on the Rawhide Lease        180
                                    xv i i i

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Number                                                                   Page
6-11   Minimum and Maximum Values at Carter Oil North Rawhide Lease
       for Water Quality Parameters (coal aquifers)                       181
6-12   Chemical Analysis of Water from Wells within 6 Miles of Property
       Boundary of Proposed Kerr-McGee Jacobs Ranch Coal Mine             182
6-13   Laboratory Analysis of Water from Stock and Domestic Wells
       Drilled Prior to Granting of Lease to Kerr-McGee                   183
6-14   Groundwater Quality, Hayden Residence, Sun Oil Cordero Lease       185
6-15   Groundwater Quality, Well Number 11, Sun Oil Cordero Lease         186
6-16   Minimum and Maximum Values for Wyodak Mine Water Quality
       Parameters                                                         187
6-17   Water Quality Analysis Summary                                     188
6-18   Water Quality Analysis Summary- Gillette, Wyoming, Water
       Supply, 1976                                                       189
8-1    Characteristics of the Soils                                       211
10-1   Project Area Potential Pollution Source Priority Ranking by
       Major Category                                                     228
                                     xix

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                   LIST OF ABBREVIATIONS


ANFO        ammonium nitrate-fuel oil

BOD         biochemical oxygen demand

CEC         cation exchange capacity
COD         chemical oxygen demand

DEQ         Department of Environmental Quality
DMA         designated monitoring agency
DO          dissolved oxygen
DOC         dissolved organic carbon

EC          electrical conductivity
ECe         EC of  soil paste extract
ED          electrodialysis
EIS         environmental impact statement
EPA         Environmental Protection Agency
ESP         exchangeable sodium percentage

I/I         infiltration/inflow

JTU
(turbidity) Jackson turbidity units

ILL         Lawrence Livermore Laboratories

MBAS        methylene blue active substances

nd          no date
NPDES       National Pollution Discharge Elimination  System

PAH         polycyclic aromatic hydrocarbons

RO          reverse osmosis

SAR         sodium adsorption ratio
SCS         Soil Conservation Service
SV solids   suspended volatile solids

TDS         total dissolved solids
TOC         total organic carbon
TPD         tons per day
                            xx

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      Chemi cal s and Eements
As
Be
Ca
Cd
CdS
Cr
Cu
CuS
Fe
FeS
Hg
HgS
Mo
NH|
Ni
N02
NOX
Pb
PbS
arsenic
beryllium
calcium
cadmium
cadmium sulfide
chromium
copper
copper sulfide
iron
ferrous sulfide
mercury
mercurous sulfide
mercuric sulfide
molybdenum
ammonium
nickel
nitrogen dioxide
mixed nitrogen oxides
lead
lead sulfide
Se    selenium
      sulfur dioxide
U     uranium
V     vanadi urn
Zn    zinc
ZnS   zinc sulfide
                xx i

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                                ACKNOWLEDGMENTS


     Dr. Lome  G.  Everett of General  Electric-TEMPO was responsible for manage-
ment and technical  guidance of the project under which this  report was  prepared.
Dr. Richard M.  Tin!in,  Camp Verde, Arizona, was responsible  for  the organiza-
tion and presentation of the report.   Principal TEMPO  authors were:

                           Mr.  James D.  Brown
                           Dr.  Lome G.  Everett
                           Mr.  Edward  W.  Hoy!man
                           Dr.  Guenton C.  Slawson, Jr.

     Principal  consultant authors  were:

                           Dr.  S.N.  Davis
                           Ms.  Margery A.  Hulburt
                           Mr.  Louis Meschede
                           Dr.  Roger Peebles
                           Dr.  Kenneth D.  Schmidt
                           Dr.  John  L. Thames
                           Dr.  Richard M.  Tin!in
                           Dr.  David K. Todd
                           Dr.  Donald  L. Warner
                           Dr.  L. Graham Wilson
                                      xxn

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                                  SECTION 1

                                 INTRODUCTION


     Groundwater  is an  important natural resource in the United States.  It
supplies  an estimated 68  billion gallons* per day to .the nation's fresh water
supply  (Murray  and Reeves,  1972).  Nearly half of the nation's population
receives  its drinking water from groundwater sources (U.S. Environmental
Protection Agency, 1976a).

     Emphasis on  the need to protect groundwater quality has been provided by
the  United States Congress  through the Federal Water Pollution Control Act
Amendments of 1972 (Public  Law 92-500) and the Safe Drinking Water Act of 1974
(Public Law 93-523).  These laws give the U.S. Environmental Protection Agency
(EPA) a major responsibility for preventing degradation of groundwater re-
sources.

     Coal is one  of the nation's most abundant energy sources.  Because of its
low  sulfur content, Western coal is generally preferred over Eastern coal for
environmental reasons.  As  a result, Western coal is being strip mined at
unprecedented rates.

     Traditionally, groundwater monitoring activities have been designed to
assess the quantity and quality of groundwater for a particular use.  To pre-
vent, reduce, and eliminate groundwater quality degradation, as called for in
P.L. 92-500, a  monitoring program must do more than this.  It must provide a
systematic approach for detecting and delineating groundwater pollution before
the  pollution reaches points of groundwater use, and preferably before the
pollutants enter  the ground.  It must focus on identifying the pollution
sources,  specific pollutants, and their respective mobilities through the
hydrogeologic system.  Whether a pollutant reaches a point of water use can
no longer be the  determining factor as to what constitues groundwater quality
•degradation.

     In response  to the high priority placed on Western coal development, the
U.S. Environmental Protection Agency awarded a 5-year contract to General
Electric-TEMPO  of Santa Barbara,  California, based on its systematic approach
to predictive groundwater quality monitoring.  The approach provides for the
utilization of  a  15-step  methodology (Todd et al., 1976) which includes the
identification, quantification, and ranking for monitoring of the important
sources of groundwater quality degradation within a given study area.

* See Appendix  A  for conversion to metric units.  English units were used in
  this report because of  their current usage and familiarity in industry and
  the hydrology-related sciences.

                                      1

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 CRITERIA FOR SELECTING THE MONITORING AREA

      In 1969, the important coal-producing  States  in the West - Arizona,
 Colorado, Montana, New Mexico,  North  Dakota,  Utah, and Wyoming  - had 36 strip
 mines which averaged about 400,000  tons yearly  per mine.  By 1972, the number
 of mines had dropped to 28, but production  had  increased to about 1 million
 tons per mine.   Presently there are approximately  60 existing coal mines in the
 Western States  (excluding Washington, Texas,  and Oklahoma), and  1976 production
 was somewhere on the order of 100 million tons.  The Federal Energy Adminis-
 tration estimates that Western coal mines in  1985 will produce  approximately
 570 million tons from about 150 mines.

      The coal strip mining activities within  this  seven-State area were review-
 ed by the EPA in order to locate candidate  study areas.  Once this was accom-
 plished, the candidate areas were rated in  terms of the degree of attention
 they were getting in terms of groundwater quality monitoring activities.

      Out of the several  candidate areas, the  coal field along the eastern edge
 of the Powder River Basin, located  within the State of Wyoming and mostly with-
 in Campbell County, was selected for  study.   Campbell County is  reported to
 contain about 50 percent of Wyoming's coal  resources and approximately 84
 percent of its  known strippable coal. At least 20 billion tons  lies within
 200 feet of the surface and, therefore, is  recoverable by strip  mining methods
 (Breckenridge et al., 1974).

      One important long-term objective of this  study is to develop a reference
 manual  for use  in developing monitoring programs to assess the  impact of coal
 strip mining on groundwater quality in other  areas of the Western coal-
 producing region undergoing similar development.   It is anticipated that
 monitoring activities developed using this  manual will eventually become part
 of a State's overall  environmental  monitoring program -  air, land, and water.
 As a result, the selection of the areas ideally should be made within a State,
 by the appropriate State water pollution control agency that, in cooperation
 with the EPA, carries out the mandates of P.L.  92-500 and P.L.  93-523.

      The basis  for selecting these  areas will be governed, collectively, by a
 combination of  administrative,  physiographic, and priority considerations.
 These factors are reviewed in the following paragraphs and then  applied in
 exemplary fashion specifically to the project area to illustrate the area
 selection process.

 Administrative  Considerations

      The  initiation of a monitoring program requires that a locally designated
 monitoring  agency be  specified.   In many situations, the requisite agency with
 the  necessary technical  staff may be  a county,  district, State,  or regional
 water organization.   Thus,  the  area to be monitored can often be made to corres-
 pond  to the  jurisdictional  area  of  the designated monitoring agency(DMA).

     Selection of the DMA may involve a review  of a State's institutional
 structure.   In some instances,  it will be readily apparent which agency should
be designated as  the  monitoring  agency.  In other  instances, several agencies

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may have overlapping responsibility and authority.  Situations such as this may
require organizational changes to provide an efficiently operated DMA.

Physiographic Considerations

     The physiographic basis for selecting monitoring areas results from the
fact that groundwater basins are distinct hydrographic units containing one or
more aquifers.  Such basins usually, but not always, coincide with major sur-
face water drainage basins.  By establishing a monitoring area related to a
groundwater basin, total hydrologic inflows to and outflows from the basin are
fully encompassed.

Priority Considerations

     Resource administrators at all levels, Federal, State, and local, are
faced with a common problem -  how to allocate monetary resources equitably to
deal with a host of environmental problems.  For political reasons, these
individuals must be attentive to the needs of all areas under their jurisdic-
tion.  Rarely are funds available in a timely manner to deal with more than
just a fraction of the problems brought to their attention.  A procedure for
establishing priorities for both existing and potential environmental  impacts
for monitoring and control would be particulalry useful.

     The following discussion details the application of the administrative,
physiographic, and priority considerations to the selection of Campbell County
as the project area, and this is followed by a description of how the  priority
establishment scheme works, before presenting the results of the first attempt
to rank the sources identified in the project area for monitoring.

SELECTION OF THE PROJECT AREA

     The eastern part of the Powder River Basin will be subject to the most
intensive strip mine development in Wyoming.  The major coal fields are loca-
ted in Figure 1-1.  The coal beds along the eastern edge of the basin  outcrop
along a line trending roughly southeast to northwest.  Almost all the
strippable coal in these beds is located within Campbell County.  In order to
select that portion of the coal field best suited to meeting the goals of this
research effort, the generalized administrative, physiographic, and priority
considerations previously discussed are now applied specifically to the selec-
tion of the project area.

Administrative Considerations

     A primary administrative consideration is the selection of the DMA.  In
Wyoming, several candidate organizations for the DMA exist -  the State
Engineer's Office, the State Geological Survey, and the Department of Environ-
mental  Quality (DEQ).

     The DEQ, because of its assigned responsibilities for environmental qual-
ity, is the State agency most suited to become the DMA.  The DEQ has divided
the-State into five physiographic basins -  Big Horn Basin, the Northeast
Basin,  the Platte River Basin, the Green River Basin, and  the Bear and Snake

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                                          MONTANA
                                                      COLORADO
                     50
                    MILES
                                100
                               =d
MAJOR COAL BEARING AREAS
STRIPPABLECOAL
PROJECT AREA
Figure  1-1.  Major coal fields of Wyoming (adapted from U.S.  Geological  Survey,  1974a)

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River Basins.  The Northeast Basin encompasses the project area and consists
of three subbasins -  the Powder River, Belle Fourche, and Cheyenne River.

     The Northeast Basin has an engineer in charge of overseeing environmental
monitoring activities.  He works with the various county and city governments
in the execution of the DEQ's responsibilities.

     Campbell County lies completely within the Northeast Basin.  One impor-
tant factor  in determining the size of the project was to confine the study to
a single political unit and to within short distances from an urban center, in
this case the City of Gillette.  Campbell County provides an area large enough
to obtain the necessary regional perspective to provide results which are
representative of the impacts on groundwater quality due to coal strip mining
in the Powder River Basin and many areas of the Western States.

Physiographic Considerations

     Initially, a rectilinear boundary was established to serve as the project
boundary until proper physiographic boundaries could be identified.  This
boundary is  shown in Figure 5-1, by the dotted line.  The initial boundaries
were later superseded by the physiographic boundaries of the five watersheds
delineated in Figure 5-1, by heavy black lines.  Locally within the above
watershed areas, the recharge and shallow groundwater table conforms to the
topography and local geology.  The coal seams in the area, however, are region-
al in extent and dip gently in the opposite direction or westerly direction
from surface flows.

Priority Considerations

     The emphasis of the monitoring program is on water quality changes direct-
ly associated with the strip mining of coal.  However, various nonmining
activities associated with the development of the coal are included in the
scope of the program.

     The major sources not directly attributed to the mines are municipal
(sewage treatment, water treatment, landfills and dumps, and urban runoff),
agricultural and livestock production (fertilizers, soil amendments, pesti-
cides, irrigation, stockpiles, and animal wastes), and various industries
(e.g., oil and gas extraction and the construction inoustry).

IMPLEMENTATION OF THE PRIORITY RANKING SCHEME

     The priority ranking scheme which follows is designed to progress through
the groundwater quality monitoring methodology (Todd et al., 1976) three
times, each time at a different level of intensity, each time progressing
further into the later steps of the monitoring methodology, and each time
accomplishing a different goal.

Level One

     The first time through the ranking scheme, several objectives are met:
to review the existing data and information on known sources and causes of

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 groundwater pollution,  to  identify potential sources and causes of ground-
 water pollution,  to  identify  the potential pollutants associated with both
 of these  pollution source  groupings, to evaluate the hydrogeological frame-
 work  insofar as  it relates  to  these known and potential sources and causes
 of pollution, and to  superimpose these sources and pollutants on the hydro-
 geologic  framework to determine their mobilities.  The final goal in this
 first pass  through the  scheme  will be assignment of monitoring priorities to
 those sources which appear  to  present the greatest threat to the area's
 groundwater quality.

 Level  Two

      Implementation of  the  monitoring program will require a return to the
 initial methodology steps.  This time the objective will be to verify the
 preliminary priority  ranking of sources with hard data and will involve
 designing monitoring  approaches for each source under investigation.  This
 exercise  will require considerable time, depending on the number of sources
 involved  and the  size of the area -  perhaps several years to a decade or more
 to  reach  a  mature stage.   It  is likely that the intensive monitoring will
 result in a revision  of the original priorities.  In time, some monitoring
 activities  will need  to be  decreased or completely eliminated, while others
 will  need to be intensified.

      When the results of this  second pass through the ranking scheme are used,
 a much more accurate  estimate  of the threat to the area's groundwater quality
 will  be available, and  controls can be devised to deal, with the threat.  If
 the need  for instituting controls is obvious after the first assignment of
 priorities,  they  should be  implemented immediately.  The implementation of
 controls  will again require funding by the appropriate State agency.

 Level  Three

     The  final pass through the priority ranking scheme will involve monitor-
 ing to check on the effectiveness of the controls implemented.  If these
controls  are proven effective, then the intensity of monitoring can be re-
duced  and eventually  dropped if the threat can be shown to no longer exist.

     New  sources  of potential  pollution will continually appear.  The monitor-
ing program  should plan to  include these sources.  They should be brought
into the  program  through the orderly process of Environmental Impact Reviews
by State  and Federal  agencies.

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                                   SECTION 2

                        POTENTIAL SOURCES OF POLLUTION
                           AND METHODS OF DISPOSAL
     The basic TEMPO classification scheme for potential sources in the proj-
ect area includes three major categories:  Agricultural, Industrial, and
Municipal.

     Agricultural activities in the project area are relatively minor.  The
major agricultural activities are grazing cattle and some dryland farming.
Groundwater usage was, and still is, meager for these purposes.

     The major emphasis in this study is on coal  strip mining, which falls
under the Industrial source grouping.  A closely related Industrial  activity
is coal conversion via steam power generation, gasification, or liquefaction.

     To meet the needs of the coal mining and allied industries, the City of
Gillette, outlying communities, and construction camps will  need to provide
additional services, e.g., disposal and treatment of liquid  and solid wastes,
and expanded municipal water supply and treatment facilities.  The result of
this expansion will be a greater number of potential pollution sources.  The
impact of these sources has been given detailed review, in particular those
related to the City of Gillette.

     The potential pollution source inventory which follows  summarizes the
result of an intensive review of all the published material  available in the
project area related to proposed development of the seven mines of interest,
and numerous discussions with the environmental staffs for those mines.  Many
discussions were also held with city, county, and State personnel involved
in meeting the needs of the coal development and providing adequate environ-
mental controls for this development.

AGRICULTURE

     Ninety-four percent of the land in Campbell  and Converse Counties is
pastureland; consequently, most farming is conducted by livestock operations.
The major crops are hay and forage.  Very little farmland is irrigated.

     According to the Farmer's Cooperative in Gillette, which is the major
outlet for agricultural products in Campbell County, very few, if any, soil
amendments are used in the county. The County Agricultural  Agent stated  that
very little fertilizer is used.  Herbicides are used in the County  in  small
amounts, primarily along highway rights-of-way, and very few pesticides are
normally used.

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      According to the U.S.  Bureau of  Land Management  (1974), grazing of range
 beef cattle and sheep is  the  predominant land use in  Campbell County.  The
 average ranch  is about 260  animal units, one animal unit being year-round
 support for one cow and calf  or  five  sheep.

      The County Agricultural  Agent stated (personal communication) that al-
 though there is a large amount of livestock in Campbell County, there are no
 feedlots in the County at this time.  The County Agricultural Agent also
 stated that dead animals  are  generally left where they fall to be consumed by
 predators.

 INDUSTRY

      Two main  groupings were  used to  examine th6 impacts of potential pollu-
 tion sources from coal  strip  mining on groundwater quality, active mining
 sources, and reclaimed area sources.  Active mining sources are those sources
 which result from the actual  mining operations and are of a transitory nature.
 Reclaimed area sources  are  those sources which are the result of reclamation
 activities  following the  completion of active mining.  These sources are ex-
 pected to remain in place indefinitely.

 Active Mining  Potential Pollution Sources

 Stockpiles-

      Stockpiles can act as  groundwater pollution sources when rainfall or
 melted snow percolates  through the stored material, dissolving pollutants' and
 transporting them to the  groundwater  system.  They are also subject to leach-
 ing  due to  seepage from ponded surface waters or artificially applied waters.

      Classes of material  that may be  stored in stockpiles during the active
 mining phase are topsoil, overburden, coal, coal refuse, coaly waste, and the
 partings that  occur between coal seams.  Stockpiles may be very temporary or
 they may exist for the  life of a mine.

 Topsoil -

      In all  Powder River  Basin coal mines some topsoil will be selectively
 removed and  stockpiled  before being replaced on top of graded overburden.
 Commonly, topsoil  from the  first area to be mined will be stockpiled because
 there is no  place to use  this topsoil at the beginning of mining.  For exam-
 ple,  in the  case of one mine, the topsoil removed from the first area to be
 mined will  be  stockpiled  until it is  used to cover the final area to be mined
 in about the year 2000.   Topsoil might also be stockpiled for blending to up-
 grade the quality of reclamation soil cover.

 Overburden-

      As  described here, overburden is that material lying between the topsoil
and  the  mineable coal  beds.   In  the area of study, the mineable coal lies at
or near  the  top of the  Fort Union Formation and the overburden is sandstone,
shale,  carbonaceous  shale,  and thin or impure coal beds of the Wasatch or

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 uppermost Fort Union  Formations.   In  local  areas,  along  the outcrops  of  coal
 beds,  a  unique rock type  has  been  formed  by the  baking of  shale and siltstone
 by  burning coal  beds.   The  baked material  is commonly called  scoria or clinker
 and it may also be incorporated in the overburden.  An additional type of
 overburden is  the alluvium  found in the stream valleys.  It consists  of  sand,
 silt,  and clay derived  from the bedrock units.   Overburden thicknesses in
 operating and  proposed  mines  range from none at  the outcrop of the mineable
 coal',  up,to perhaps 300 feet  as the coal  beds are  traced westward into the
 Powder River Basin.   The  thickness of overburden that can  be  removed  at  a mine
 is  based on economics and available technology.

      During the mining, the overburden is  removed, the coal extracted, and the
 overburden then replaced  and  graded to the  desired topography.  Overburden is
 removed  during early  development of a mine  and is  stockpiled  because  there is
 no  previously  mined area  in which  to  place  it.

 Coal,  Coal Refuse, and  Coaly  Waste-

      Coal, coal  refuse, and coaly  waste are considered together since they are
 geologically and chemically similar.  Coal  refuse  is used  here to mean the
 fine coal  and  waste material  removed  during the  coal preparation process.
 Coaly waste is used here  to describe  the  thin coal seams,  impure coal, and
 carbonaceous shale that may occur  in  the  overburden and  within the partings
 between  coal seams.   However,  these materials are  identified  separately, in
 spite of their geological and chemical similarity, because they are handled
 differently and, therefore, have different  water pollution potentials.

      Coal, the commercial product,  is handled carefully.   It  is mined soon
 after exposure by stripping and is not allowed to weather  or  to have  much
 water percolate through it  to pick up pollutants.  After mining, it will
 usually  be processed  in some  manner.  Common steps in coal processing include
 crushing,  screening,  and  washing.   Coal at  Powder River  Basin mines is usu-
 ally only crushed.  After crushing, coal  is temporarily  stored in silos,
 bunkers, or open piles.   Although  open piles are the exception, they  may
 occasionally be used.

      Coaly waste is considered separately  from the remainder  of the over-
 burden because it usually has  a different  type and amount  of  water pollution
 potential.  Its  geochemical properties also affect its potential as a soil-
-forming  material.  Such materials  commonly  form  toxic soils and are thus
 segregated from the other overburden  during mining.  A frequent method of
 handling is to attempt  to place the coaly waste  at or near the bottom of the
 spoil.   In order to selectively place the coaly  waste, it  may be necessary
 to  stockpile it temporarily.

 Partings-

     Partings  that occur  between coal seams could be considered along with
 the overburden,  rather  than as a separate category.  The reason for consider-
 ing partings separately is  that they  are  likely  to be different from  the
 "average"  overburden because  they  tend to be principally shale and carbona-
 ceous  shale and  because their  location may  be cause for  handling them

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 differently  from  the overburden.  Partings might be stockpiled temporarily to
 allow  for  selective placement  in the spoils.

 Explosives-

     Either  the overburden or  coal, or both, may be blasted at a mine, depend-
 ing on the degree of consolidation of the material.  The principal explosive
 now being  used for blasting at the strip mines is an ammonium nitrate-fuel oil
 mixture  known as ANFO.   In the case of a complete explosion during blasting,
 the solid  ammonium nitrate would be entirely converted to gaseous forms and
 ultimately be lost to the atmosphere.  In the case of an incomplete explosion,
 some ammonium nitrate residual will occur.  Apparently no studies have been
 made to  determine precisely the amount of residual to be commonly expected in
 the project  area.

 Solid  Wastes for  Road Construct!on-

     A common practice  in strip mine development is to construct access and
 haulage  roads from overburden.  It has been observed at the mines visited that
 most permanent roads are being constructed of scoria, or clinker.  However,
 some roads  have been constructed of overburden.

 Discharges  into Pit and Methods of Disposal -

     Water entering pits can originate from a number of sources, each of which
 may already  contain pollutants derived in a number of ways.  Pit water thus
 would  generally be expected to contain some pollutants.'  Pit water is even-
 tually disposed by several different methods.  As such, the pit discharge is
 itself a potential source of pollution.  The following discussion lists the
 sources  of pit water as well as the methods of disposal of pit discharge.

     Water  in the pits  may come from a number of sources, such as:

     •  Direct precipitation in the pit

     •  Runoff into the pit

     •  Water percolating from nearby stream channels, generally
         through alluvium along the floodplain

     •   Liquid wastes (such as septic tank effluent)

     •   Groundwatar in  the overburden

     •   Groundwater in  spoils

     •   Groundwater in  the coal seam being mined

     •   Groundwater in  underlying coal seams and strata.

     For mines in the Gillette area, the method of disposal for most of  the
pit discharge will be dust control.  Secondarily, the pit discharge will  be


                                     10

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used for irrigation of reclaimed spoils during the early stages of reclamation.
Discharge to surface water will also commonly occur when there is excess pit
water compared to potential use.

Supplemental Sources of Water-

     Supplemental water for dust control and coal  processing may be obtained
from pumpage of deep wells or by importing sewage effluent or both.

     Pumpaqe of deep groundwater-It  is  theoretically possible for  poor qual-
ity waters pumped from deep aquifers to pollute shallow groundwater systems.
However, in the project area, the deeper waters are generally of better qual-
ity than shallow waters.  Available data indicate that the shallow Wasatch
Formation waters have the poorest quality of any waters in the area.

     Pumpage from the deep aquifers in the project area is limited to a few
subdivisions and the coal mines.  All drinking water supply wells for the
mines produce from the Fort Union Formation.

     Imported sewage effluent-The  principal  source of  sewage effluent for
importation in the project area is from the City of Gillette treatment plant.
This plant receives not only domestic wastes from the City, but also periodic
discharges of industrial wastes.

     Sewage flows from the City of Gillette treatment facilities may impact
on the quality of groundwater in two ways:  (1) seepage losses in Donkey
Creek and (2) direct drainage into mine pits.  Seepage loss is a function of
such factors as temperature and entrained substances.  Temperature affects
infiltration through viscosity relationships.  Entrained substances, parti-
cularly sediment, orgam'cs, and microorganisms may clog the surface of the
channel, reducing intake rates.

     The problem of seepage losses in Donkey Creek will be largely eliminated
following the completion of a pipeline which will  transmit effluent from the
City of Gillette to a reverse osmosis (RO) unit at the Wyodak mine.  However,
seepage losses in the pipeline must also be considered a potential  source.

     Water treated in the RO unit wil.l be used as process water in the nearby
Neil Simpson Power Plant.  Brine from the RO unit will  be discharged to an
evaporation pond for disposal.  Leakage from the pond should be considered as
a potential source.

     Surplus sewage effluent (above requirements for the RO plant) will be
used for dust control.

Mine Sanitary Wastes-

     Three types of treatment facilities may be used to treat sewage generated
in the mine site:  septic tanks, package plants, and oxidation ponds.

     Septic tanks-Overflow for  septic tanks  is  generally discharged into
leaching fields.  Areal  requirements for leaching fields with continuous


                                      11

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inundation should be 0.5 gallon per square feet (gal/ft )  per day  for inter-
mittent operation.  Effluent percolating beneath a leach field poses  a threat
to groundwater quality, particularly if the vadose zone consists of fractured
rock.  Sludge must be pumped from the septic tank units periodically.  Sludge
could be used as a soil conditioner, possibly leading to pollution.

     Package plants-Prefabricated  package  plants  are  generally used  to treat
sewage for small subdivisions, schools, and other installations,  with loadings
of 1 million gallons per day (mgd) or less.  Package plants operate to provide
extended aeration of sewage -a variant of the activated sludge process.
Units consist of two compartments:  a clarifier chamber and an aerator tank,
where air is forced into raw and recycled sewage.

     Two problems exist with package plants, vis-a-vis potential  impacts  on
water quality of the receiving stream or groundwater.  First, package plants
are  very sensitive to shock loading, e.g., rapid changes in diurnal flow  rates.
Treatment becomes relatively ineffective following shock loading  such that
effluent quality released from the plant becomes very poor.  Secondly, because
primary settling is generally omitted in commercial plants, discharge of  sol-
ids  may become objectionable.

     Oxidation ponds-Oxidation  ponds are commonly  used  in  small communities
to treat raw sewage.  In fact, if designed properly, ponds may attain second-
ary  treatment (U.S. Environmental Protection Agency. 1976b).   Three types of
ponds are commonly used:  aerobic ponds (mechanical aerators), facultative
ponds (aerobic-anaerobic) and anaerobic ponds.  Basically, aerobic ponds  rely
on a symbiotic relationship between bacteria and algae to stabilize sewage.

     Ponds may leak if inadequately sealed and possibly contribute to ground-
water pollution.  Generally, a natural  seal is induced in time by  infiltrating
organics.

Mine Solid Wastes-

     Solid wastes generated by mining operations (excluding spoil) may be
disposed of by one or more of the following:

     •  Onsite landfills

     •  Offsite disposal by landfills

     •  Incorporation in mine spoils

     •  Incineration followed by land disposal of residue.

     Onsite disposal may be accomplished using open dumps or sanitary land-
fills.  Open dumps, as the name implies, consist of dumping solid wastes on
the  surface of the ground, or over embankments.  Occasionally, open  dumps  are
burned.   An advantage of onsite landfills, properly designed and constructed,
is that the solid waste is concentrated at one place.  Monitoring  of types of
solid wastes is facilitated, as well as groundwater monitoring.
                                     12

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     The same discussion given above for onsite disposal applies to offsite
solid waste disposal sites.

     Solid wastes generated by mining activities are often incorporated with
mine spoils and dumped into the mine pit.  Groundwater moving into the spoil
piles is potentially capable of leaching solid wastes, producing leachate.
In contrast to onsite or offsite disposal, solid wastes are generally placed
haphazardly in the spoils.  Consequently, groundwater monitoring becomes a
difficult operation.

     Combustible solid wastes may be incinerated to reduce bulk.  The residual
ash may then be placed in landfills or into spoil piles.  Leaching of buried
ash may subsequently occur by surface or groundwater influx into the landfill
and spoil pile.

     Fly ash removed by the incinerator gas stream may settle on the ground
surface for considerable distances from the incinerator.  Settled ash repre-
sents a potential source of surface and groundwater contamination.

Liquid Shop Wastes-

     Maintenance and servicing of mine equipment will  be likely to produce
some liquid wastes, such as oil and wash water.  In most cases the mining
companies have simply stated that liquid shop wastes will be disposed of in
a manner complying with State and Federal regulations, but no details have
been given.

     Much of the equipment will probably be washed outside, with the water
running off onto the ground.  Possible pollutants include salts in the mate-
erial being washed off of the equipment, soap or detergent that may be used,
and salts or toxic elements in the water used for washing.  Washing will
probably be concentrated in a relatively small area near the building and shop.

Spills and Leaks—

     Wherever liquids are held, there is the potential for leaks.  The mines
keep liquids such as gasoline, oil, and diesel fuel in storage tanks, either
buried or above ground, and in some cases, pipelines connect these storage
tanks with points of use.  Package treatment plants, with associated pipe-
lines, and storage vessels for ammonium nitrate and fuel oil also have a po-
tential for leaks.

     Spills can occur in the process of transporting all of the above mate-
rials and during loading and unloading storage tanks.   Lubricants and other
materials used for servicing equipment have the potential of being spilled
both in the shop and at the pit, depending upon where servicing is taking
place.

Reclaimed Area Potential  Pollution Sources

     Site reclamation fill  materials are those that will be within or closely
associated with the mined area.  After mining, the overburden (spoils) will


                                    13

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 be replaced within  the mined area.  The spoils will consist of various sub-
 categories of  geologic materials  including coaly waste, interseam partings,
 and refuse from  coal  preparation, if any is produced.  Various solid wastes
 may also  be disposed  of within the spoils.  This was observed to be the prac-
 tice at many of  the mines, which  are reported to be licensed landfills.  Top-
 soil  that is determined to be of  good quality for plant growth will be spread
 on the graded  spoils.  Poor quality soils will be incorporated within the
 spoils.

      These fill  material sources  may contribute to groundwater pollution in
 several ways.  As with stockpiles, precipitation may percolate through the
 materials, dissolving soluble chemicals and carrying them to the groundwater
 system.  Additional mechanisms of pollution are percolation of surface water
 from streams,  ponds,  and lakes, and the movement of groundwater through the
 mined area.  A common circumstance in Powder River Basin mines is the pres-
 ence of a stream that passes through the mine area.  The streams are being
 diverted  during  the course of mining, but subsequently will be rechanneled
 through mined  areas.  Ponds and lakes may be developed within the mined area.
 Some mining plans include a lake  in the final strip cut.

 Reclamation Aids-

      Fertilizers and  soil amendments have some potential for groundwater pol-
 lution.  The AMAX Belle Ayr South mine is reported to be planning application
 of not more than 20 pounds per acre of nitrogen in the form of ammonium ni-
 trate; in most cases, 20 pounds of phosphorus in the form of superphosphate,
 essentially monocalcium phosphate.  Wood fiber and straw mulches are commonly
 used in the project area to reduce soil loss and conserve moisture.

      The  primary fertilizer dealer in Campbell County is the Farm Bureau
 Co-op. There, nitrogen (ammonium nitrate) is available with a fertilizer
 grade of  34-0-0, and  as a mixture with superphosphate, having an analysis of
 18-46-0.  One  mine  buys the 34-0-0 and 18-46-0 fertilizer grades and mixes
 these to  obtain  a higher nitrogen content of the applied fertilizer.  The
 Farm Bureau employee  was of the opinion that Campbell County is now in the
 experimental stages of fertilizer application, with some farmers believing
 strongly  in its  benefits, and others disclaiming them.  Fertilizer is used
 primarily in Campbell County on wheat, barley, and some grasses.

      Ammonium  nitrate is manufactured for use in explosives and as a fertil-
 izer.   Because it is  very soluble in water when used as a fertilizer, it
 leaves no residue in  the soil if  sufficient moisture exists to stabilize it.
 Because the two  types of nitrogen salt which compose this fertilizer have
 the ability to move up and down in the soil solution, it should be consider-
 ed a  potential pollutant.

      The cationic nature of ammonium ions permits adsorption and retention
 by soil colloidal material if the exchange capacity of the soil is sufficient-
 ly high; otherwise  it will be removed in percolating water.

Once ammonium is nitrified, it is subject to leaching as it is completely
mobile  in soils.  Under conditions of excessive rain and high water table  it


                                    14

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may reach the groundwater.  This downward migration is likely to occur near
streams.  Where evapotranspiration is greater than precipitation, nitrogen
salts may migrate vertically upward to the land surface.

     Because the phosphate ion is almost immobile in the soil, phosphorus
moves very slowly from the point of placement.

OIL AND GAS EXTRACTION

     Oil and gas have been discovered in 210 fields in the Eastern Powder
River Basin, Figure 2-1.  The remaining recoverable reserves in these fields
have been conservatively estimated at 221 million barrels of oil and 508
billion cubic feet of natural gas.  Ninety percent of the oil  is produced
from the early Cretaceous Muddy Sandstone and the Minnelusa Formation of
Pennsylvanian age.

     According to the Consolidated Oil and Gas Co. (personal communication),
in most cases, oil and gas occur together.  An oil/gas mixture is pumped out
of the well, and the two are separated on the surface.  The gas is piped off,
while the oil is collected in an onsite battery of storage tanks.  When the
tanks are full, the oil is tested for water content and is then transported
to the customer via pipeline.

     A local rancher has reported that leakage from storage tanks is a con-
tinuing problem; the oil has polluted the surface water in local drainage.
He also reported that during drilling the sides of the mud pits, used for
circulating water and drilling mud, broke open several times,  releasing mud,
water, and oil into a nearby stream.  Leaks and spills of this type appear
to be an important potential pollution source associated with oil and gas
extraction.

     Other potential sources of pollution include seepage through the bottom
of the mud pit and the entrance of water into shallow aquifers through leaks
in the casings of injection or disposal wells.

     Every oil well and test hole that has been drilled had a mud pit associ-
ated with the well at the time of drilling.  These mud pits are used for mix-
ing drilling mud and for circulating water used in drilling.  When a well or
test hole is abandoned, the mud pit must be filled in and "reclaimed."  No
site-specific information is available at this time on evaporation ponds or
brine disposal wells.

CONSTRUCTION

     Campbell County is the fastest growing area in the State of Wyoming.
This growth rate is reflected in large-scale construction activity in the
area.  Approximately 1,000 housing starts per year are anticipated by the
City of Gillette, 600 within the City during 1977 and the balance in adjacent
county areas.  Also, numerous duplexes and apartment buildings are slated to
be built in the coming years.

     Industrial construction is also active.  A large shopping area is planned


                                    15

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                "    RRR    RRR    RRR   RRRR    RR
               79W  78W 77* 76W 75W 74W 73W  72W 71W 70W 69W 68W 67W 66W  65W 64W
          T58N
          T57N
                                                                Oil and gas field
                                                                    (Abd)
                                                                Abandoned field
                                                                  Oil pipeline
                                                                  Gas pipeline
                                                                     A
                                                                   Refinery
        T32N
                                10
                                      20
30     40
                                                           50 M.les
                                0    10   20   30   40   50 Kilometers
Figure 2-1.   Oil  and gas  fields  associated with the  Eastern  Powder River Basin,
               Wyoming (U.S.  Department  of Interior, 1974)
                                           16

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near the (£ut-across Road, south of Interstate 90.  East of this planned shop-
ping center, a motel is being built.  The facility is scheduled for comple-
tion in fall 1978.  North of Gillette along Wyoming Highway 14-16, new steel
buildings are being erected.  The newest building will be a parts depot for
mining equipment.  Tractor dealerships, welding shops, and other businesses
occupy other recently constructed buildings.  The Gillette-Campbell County
airport is also growing.  One company is building new hangars and office fa-
cilities, and some individuals are building hangars for their private planes.

     Road construction  is occurring in the project area.  The gravel road
from the AMAX Belle Ayr South mine south to the ARCO Black Thunder mine par-
allels a new railroad line.  The road has been widened, new culverts have
been installed, and graders keep the surface smooth..  The road will eventually
be  oiled and graveled.  Bridges have been replaced on Wyoming Highway 59 near
Reno Junction,  and road-patching crews operated countywide through the summer
of  1977.  Wyoming Highway 59, north of Gillette, is being rerouted past the
AMAX Eagle  Butte mine and the Carter North Rawhide mine.

     A north-south railroad line is being constructed from Gillette to the
southern end of the project area.  The line is complete to approximately 12
miles south of  the Sun  Oil Cordero mine, and the operating mines have com-
pleted spur lines to the main railroad.  Field observations indicate that the
railroads will  be as far south as ARCO's Black Thunder mine by winter 1977.

     The most active construction efforts are associated with the surface
coal mines  in Campbell  County.  Although many mines will eventually extract
Federal and/or  private  coal, only seven mines within the project area have
begun substantial construction.

Methods of  Construction Waste Disposal

     Construction projects primarily generate solid waste, with limited
amounts of  waste oil and grease.  Housing construction projects dispose of
their solid waste at the Gillette Sanitary Landfill.  Nonmining industrial
construction waste is also deposited at the landfill.

     Railroad and highway construction projects use water for dust control.
Water service companies haul water to unlined storage pits, from which the
construction drivers withdraw water for dust control.  Field observations
indicate that the water used for these purposes may often be oil field waste-
water, or other nonpotable water.  The storage pits for this water are usu-
ally centrally  located  for easy access.  Leaks and spills from storage tanks
are always  possible, but few such problems have been observed in the area.

     Construction of the surface coal mines generates solid waste and small
amounts of  waste oil and grease.  The mining companies have obtained permits
to  treat the mining pits as landfills.  Therefore, solid wastes and all other
wastes generated are dumped into the mining pit and are covered with backfill
material.   Personnel  from the City of Gillette (Jeff Smith, Gillette City
Engineer,  personal  communication, 1977) stated that a large amount of mine
construction material  is disposed of at the City landfill.
                                     17

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COAL CONVERSION

Steam Electric Power Plants

     One air-cooled, coal-fired power plant is currently operating in Campbell
County and another, under construction, is scheduled to go on-line in June
1978.

     The operating power plant is Neil  Simpson Station, owned by Black Hills
Power and Light Co., and Pacific Power  and Light Co., and operated at the
Wyodak mine site.  Burning about 400 tons of coal  per day, it is capable of
producing 30 megawatts of electricity.   When the power plant currently under
construction begins operation, part of  the existing facility will  be retired.

     Combustion products from burning the coal are heat, gaseous carbon di-
oxide, water vapor, sulfur dioxide, and impurities such as suspended inorganic
noncombustibles.  These combustion products and excess air pass through the
boiler as flue gases.  Next the gases pass through a regenerative air heater
where some of the heat is transferred from the flue gases to incoming combus-
tion air.  The flue gases then enter an electrostatic precipitator, where
suspended fly ash particles are charged by an electrical field.  The parti-
cles are then attracted to grounded collector plates and are moved down the
plates into a hopper by mechanical vibration of the plates.  The electro-
static precipitator will remove about 99 percent of the fly ash and may en-
train as much as 10 percent sulfur dioxide with the ash.  It is designed to
treat about 4 million pounds of flue gas per hour.  The treated gases will
be discharged through a 400-foot stack at an exit velbcity of about 90 feet
per second during full load operating conditions.

     Potential sources of pollution from the power plants include the follow-
ing:

     •   Atmospheric emissions

     •   Fly ash from the electrostatic precipitators

     •   Neutralized demineralizer regeneration wastes

     •   Sewage treatment plant effluent

     •   Floor and equipment drainage and wash water

    •   Boiler blowdown

    •   Bottom ash sluicing water

    •   Pyrites from the pulverizer

    •   Bottom ash from the boiler

    •   Ash from the economizer.
                                    18

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     The major power plant waste material is fly ash.  It is predicted that
the new plant will produce approximately 28,000 pounds of fly ash per hour,
or nearly 400 tons per day.  The ash will be disposed of by using it as fill
in both the north and south pits of the Wyodak mine.  Once it is deposited
in the pit, it will be covered with spoil.  Water sprays will be employed at
all transfer points in order to minimize dust during ash handling.

     Water for boiler makeup will be treated for dissolved solids removal by
two parallel demineralizer trains, each  consisting of a cation exchange unit
and a mixed  bed  ion exchanger.  Periodic chemical regeneration of the demin-
eralizers will be required.  Regeneration wastes will be collected in a sump
for neutralization to a pH of  6.5 to 8,  and will then be disposed of in an
ash pond located in the north  pit.  Bottom ash sluicing water, boiler blow-
down, and floor  and equipment  wash water will also  be conveyed to the ash
pond.   Black Hills Power  and Light Co.  (1973) states that because the pond
will  be located  on top of a clay bed no  seepage of  pond water is anticipated.

      During  construction  of the new plant, sanitary wastes.from the station
and from a nearby residential  community  are being treated in an extended
aeration treatment facility.   Following  construction, a packaged treatment
plant,  including primary  settling, extended aeration, and gas postchlorina-
tion, will be used.   It will be designed to treat about 3,500 gallons per
day with a 4,000-gallon aeration, tank, a 1,000-gallon settling tank, and a
1,200-gallon sludge tank.  Treated effluent will be discharged to the ash
pond.

      Additional  solid wastes generated by the power plants are pyrites from
the pulverizer,  bottom ash from the boiler, and ash from the economizer.
Black Hills  Power and Light Co. (1973) stated that these will be disposed
of onsite.

Gasification

     The extensive coal resources of the Powder River Basin, coupled with the
need for easily  transportable  and usable fuels to high-use regions, create
the potential for development  of coal conversion facilities in Campbell County.
Although three types of conversion processes (coal gasification, coal lique-
faction, and solvent refined coal) are currently being studied in the United
States, no commerical-scale facilities are planned for Campbell County for
the immediate future.  However, since 1974 Lawrence Livermore Laboratories
(LLL) has been conducting experimental in situ coal gasification studies.
Their experimental site in the Hoe Creek watershed  southwest of Gillette is
the only coal conversion  activity identified in the study region.

     The LLL approach for in situ coal gasification conceptually involves
conversion in a  thick-50  feet or more-coal seam at depths of 500 to 3,300
feet.   Permeability of the reaction zone is created using chemical explosives.
A  permeable, fractured coal bed surrounded by relatively impermeable strata
promotes heat transfer and enhances contact of coal and reactants.  LLL
anticipates  that this will also minimize leakage of reactants and products
from the fractured zone.   In this sense, the LLL concept has been termed an
underground packed-bed reactor.

                                      19

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     The fractured zone is ignited at the top.   Ignition  is  initially accom-
 panied  by oxygen injection which is replaced by a  steam-oxygen mixture after
 the  combustion zone is established.  Some of the coal  burns  to produce process
 heat, and the steam is a hydrogen source for the gasification reaction.  Col-
 lection wells are drilled to the bottom of the  fractured  zone to collect the
 product gases (methane, carbon monoxide, hydrogen  and  carbon dioxide).  Under
 commercial operation, these products would be upgraded to pipeline quality
 in surface facilities.

     With the exclusion of surface upgrading facilities the  preceding para-
 graphs  provide the salient features of both a commercial-scale in situ gasi-
 fication facility and the small experimental operation presently existing
 near Gillette.  The remainder of this discussion deals with  the specifics
 of the  experimental program as it may result in pollution sources.

     The actual gasification phase of Hoe Creek Experiment No. 1 occurred in
 October 1976.  Activities leading to the actual burn included:

      •  Hydrologic and  geologic exploration

      •  Fracturing of the coal seam

      *  Placement of  inlet, outlet, dewatering and environmental
        monitoring wells

      «  Dewatering of fractured zone

      •  Gasification  experiment.

 These activities are  to varying degrees  potential causes of pollution.

     Prior to development of  the  gasification  experiments,  exploratory holes
 were drilled at the Hoe Creek area to  characterize  the site geology and hy-
 drology (Stone and Snoeberger,  1976).   Pump and observation wells were in-
 stalled for pump tests.  These were subsequently  used for dewatering and
 environmental monitoring.   Potential  sources of pollution from these activ-
 ities include discharge from  pump tests and interconnection of aquifers from
 faulty  well construction.

 Fracturing of the Coal  Seam-

     Prior to gasification, the coal  seam was fractured  to  enhance permea-
bility  and product recovery efficiency.   A slurry of explosive  material
called  Pourvex EL-836 was used  (Stephens and Madsen,  1977).  The  composition
of this explosive is  not available.   However,  explosive  residues  are a  poten-
tial  pollutant.  Additionally,  the fracturing of  the coal seam altered  the
hydrologic characteristics of the formation and may lead to enhanced move-
ment of gasification  byproducts from the area.

Placement of Experimental Wells—

     To provide access  to the  fractured zone and  adjacent strata,  a variety

                                     20

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of injection  (gas), outlet  (product), dewatering, and environmental monitor-
ing wells were constructed  (Figure 2-2).  These wells are potential pollution
sources by acting as conduits between different aquifers, from the burn zone
to other aquifers, and from the burn zone (or aquifers) to the surface.

Dewatering-

     After the coal seam was fractured, this zone was dewatered by pumping the
six dewatering wells and well P-l.  Pumping was continued with only short
interruption  throughout the entire experiment.  Water production rates are
shown  in Figure 2-3 and water level response in the various site wells is pre-
sented in Figure 2-4.  The  method of disposal of this water is unspecified.
At equilibrium, the dewatering produced less than 10 gallons per minute (gpm).

Gasification  Experiment-

     The fractured coal bed for Hoe Creek Experiment No. 1 was ignited on
October 15, 1976.  After one day of operation, an override occurred and essen-
tially only the top layer of the fractured zone was gasified.  An override had
been predicted from the results of post-fracturing analyses.  Gasification
ended October 26, 1976.  Approximately 130 tons of coal (16 percent of the
fractured zone) had been consumed.  Although the burned zone for this experi-
ment was small, a source of release of the byproducts of pyrolysis, carboniza-
tion and coking of coals, and partial combustion byproducts was created.
Subsequent water movement into and through the burned zone may affect the
water quality of area aquifers.  Releases at the surface by dewatering wells
during subsequent pumping are, for environmental monitoring purposes, also a
potential source of pollution.

     Subsidence of the burned area after fracturing and gasification is a
possibility.  Subsidence may alter the alignment of shallower strata creating
conditions of either aquifer interconnection or blockage.   Surface subsidence
may also disrupt runoff patterns and affect recharge.

Hoe Creek Experiment No. 2-

     The gasification phase of Hoe Creek Experiment No. 2 is expected to  take
place in October 1977.  The Hoe Creek 2 site is located about 330 feet from
the site of Hoe Creek Experiment No. 1.  The coal  seam is approximately 25
feet thick with the top located 118 feet below the surface.

     Whereas  Hoe Creek Experiment No. 1 was a small-scale two-hole gasifica-
tion project, Hoe Creek Experiment No. 2 will be carried out with a five-spot
array (Figure 2-5).  One injection well will be centrally located with four
collection wells arranged around it in a square pattern.  Approximately 1,500
pounds of chemical  explosives will be used for fracturing in the central  in-
jection well  and in each of four other explosives holes, arranged in a square
pattern rotated 45 degrees  from the square defined by the collection wells.
The explosives holes are arranged to maximize resource recovery by placing the
areas  of highest permeability in the longest flow paths.  Small explosive
charges may also be placed  in the outer flow-holes to reduce flow resistance
in the regions where flow lines converge.  The dewatering holes will also be
placed to maintain symmetry and maximize resource recovery.
                                    21

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                       • THERMOCOUPLE WELLS
                       O DEWATERING OR MONITORING WELLS
   O
 10-OW
                   O
                  12-OW
P-2°
(HFEM)
O^U o
vP*w
DW-5


0


1-7
0
HE


O^ — AIR
O
8-OW
(HFEM)

•
1-6 ±
  O
 9-OW
(HFEM)
            12
             DW-3
                              •!-!
                          •  •      •
                         1-4  CB-2    ,.8
            GAS OUT «*-O
                                       O
                                      DW-2

0    5     10ft.
0123m
                                                 .
Figure 2-2.   Hole  bottom locations (Hoe  Creek Experiment No.  1)
             (Lawrence Livermore Laboratory, 1977).
                             22

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            I
               80
               70
60
            <  SO
            c
               40
               30
                   II  I  I
                                        I   I  I  I
                    • SIMPLE CYLINDRICAL MODEL
                    A TWO-DIMENSIONAL ZONED MODEL
                    • MEASURED VALUES
                                                  AIR
                                                INJECTION
                                                               200
  Figure 2-3.   Comparison of measured and calculated water  production
                rates  for the Hoe Creek Experiment No.  1  site (Lawrence
                Livermore Laboratory, 1977).
                                     TIME (h)
Figure 2-4.  Water  levels at several locations within  the fracture zone
             as a function of time after the start  of  dewatering; levels
             indicated on the right are those reached  after 3 to 5 days
             of pumping (Lawrence Livermore Laboratory, 1977).
                                    23

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                   LEGEND
                   • DEWATERING HOLES

                   O EXHAUST HOLES WITH SMALL LIQUID PUMPS

                   O EXPLOSIVE FRACTURING HOLES

                   • EXPLOSIVELY FRACTURED GAS INJECTION HOLE

            Figure 2-5.   Plan view of the packed-bed experiment
                         (Lawrence Livermore Laboratory, 1977).

      The  coal will be ignited in the center explosive well  at  the top of the
 seam and  burned down and outward using an oxygen/steam blast.   Condensed liq-
 uids (primarily water) that precede the flame front will  be removed through
 the  exhaust holes.  The dewatering holes may be used as back-up exhaust holes
 if needed.

 MUNICIPAL SOURCES OF POLLUTION

 Sanitary Wastes

 Sewage Treatment Plant Effluent—

     The City of Gillette treatment plant receives not only domestic wastes
 from the City, but also periodic discharges of industrial wastes and snow
melt.  Its capacity as  of May 1977 was about 1.7 mgd.  The treatment plant
was originally intended to be a secondary-type facility.   Primary treatment
is minimal,  however,  with only a screen provided to remove the solids.  A
follow-up grit chamber and sedimentation tank were not included.  Thus, the
secondary unit comprising activated sludge aeration tanks functions in part
also  for primary treatment.   The capacity of these tanks has been reduced by
accumulation of sand  and other material.  Because of ineffective treatment
in the aeration tanks,  the clarifier or final settling tanks are also

                                     24

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 overloaded.   Effluent  discharging  from  the  plant  is  piped  to a  "polishing"
 lagoon  which  may or may not  function  as an  oxidation pond.

      Because  of the high water  table  at the plant, leakage from the aeration
 and clarifier tanks may be occurring, introducing essentially raw sewage into
 groundwater.   Leakage  from distribution lines onsite and seepage from the
 oxidation pond should  also be regarded as potential  sources.

      Effluent discharging from  the pond drains  into  Donkey Creek.  Aerial pho-
 tography of the area (U.S. Environmental Protection  Agency, 1976d) indicates
 that effluent may flow for a considerable distance downstream in the creek.

      Sewage flows from the Gillette treatment facilities may impact on the
 quality of groundwater in two ways:   (1) seepage  losses in Donkey Creek, and
 (2) direct drainage into mine pits.   Seepage loss is a function of such fac-
 tors as temperature and entrained  substances.   Temperature affects infiltra-
 tion through  viscosity relationships.   Entrained  substances, particularly
 sediment, organics, and microorganisms may  clog the  surface of  the channel,
 reducing intake rates.

 Sewage  Sludge-

      Sewage sludge consists  of  a mixture of sewage and settled  or suspended
 solid matter  issuing from the final sewage  treatment process.   The quantity
 and character of sludge depends to a  large  extent on the treatment process.
 For example,  sludge from the secondary settling tanks of an activated sludge
 process may contain 13,500 gallons of sludge per million gallons of sewage
 (Health Education Service, nd), and a moisture  content of 98 percent.  The
 nominal weight of dry  solids from  the process is  2,250 pounds per million gal-
 lons (Health  Education Service, nd).  The process of sludge digestion is
 intended to reduce the volume of liquid, thereby  reducing the total volume;
 and also to stabilize  the organic  matter.

      A  number of methods are available  for  disposing of sludge, including
 landfilling,  incineration, and  application  to cropland.

      The technique for handling sludge at the Gillette treatment plant
 involves settling in a pond  and/or flooding onto a nearby field.  No plans
 are currently underway to use the  sludge for agriculture because of fears
.that zinc or  other heavy metals may cause crop  damage.

      Sludge disposed of by the  Gillette treatment plant may impact ground-
 water through seepage  from the  settling pond and during spreading in the
 nearby  field.

 Sewerline Leakage-

      Leak-free sewage  systems are  nonexistent.  It is difficult to prevent
 small leaks in new systems,  and older systems develop cracks and leaks with
 age.  Most sewerline leaks are  quite minor,  and can  often go totally unde-
 tected.   Major sewerline leaks  can be detected  by puddling of sewage and/or
 odor problems.


                                      25

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     According to City officials, sewerline leakage is not a  major  problem  in
Gillette.  No problems of this type have been reported during 1977.   However,
potential leakage problems are developing.  Sewerlines in the older parts of
town are approximately 40 to 50 years old and they are probably in  poor repair.

     In summary, sewerline leaks are potential sources of pollution.  During
spring runoff periods, much puddling of surface runoff occurs, and infiltrat-
ing waters could conceivably carry sewerline leakage to the groundwater body.
However, shallow groundwater in the Wasatch Formation is discontinuous, and
the infiltrating pollutant might never reach groundwater.  Moisture curves  in
the vadose zone would have to be determined before a complete analysis would
be performed; the apparent minor nature of this problem, however, discounts
the use of the procedures.

Septic Tanks-

     Although septic  tanks are in both Campbell County and the City of Gil-
 lette  (as well as package plants), an inventory of numbers and locations is
 not  currently available.

 Water  Treatment  Plant

     The water supply for the City of Gillette is drawn from more than 25
 wells  located north of the City.  These wells are generally described as
 "hard" or  "soft" water wells.  The number of hard water wells exceeds soft
 water  wells.  Total hardness ranges from a trace (in soft water wells) to
 2,425  parts  per  million  (ppm), as CaCOs (Nelson et a!., 1976).  Recently
 (June  1977), average  hardness of raw water entering the Gillette Water Treat-
ment Plant was 128 ppm,  CaCOs-


     The Gillette Water  Treatment Plant was described by TOUPS, Inc. (1977)
as follows:

               The Gillette water treatment facilities are located
          along  the north edge of the City...They consist of a
          degasifier, a  raw water storage tank, a lime softening
          plant, and  an  electrodialysis plant, all constructed in
          1972.  The  general condition of the treatment facilities
          is poor, showing a need for substantial repair and
          maintenance work.

               Water  from the soft water wells is pumped directly
          into the treated water storage tanks with no treatment
          other than chlorination, thus bypassing the water treat-
          ment facilities.

               Water from the Fox Hills and hard water wells  is
          pumped to the first step in the treatment process, which
          is a Permutit tray degasifier, designed to  remove carbon
          dioxide,  hydrogen sulfide, and the oxidation of  iron.
          Water flows by gravity from the degasifier  to the raw
          water storage tank, which is a 42-foot diameter  steel
          reservoir with a capacity of 250,000 gallons.  A valve

                                     26

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          vault at the base of the tank can be used to control the
          flow of water to the next step, which is pretreatment by
          partial lime-softening and iron removal.

               A chlorine feed system for the water supply is lo-
          cated near the main pump station.  Metering equipment
          consists of three Fischer and Porter chlorinators.   The
          chlorine feed equipment and accessory equipment do not
          meet minimum standards set by the' State of Wyoming.

     As of June 1977 the electrodialysis plant was not operating because of
severe coating of the electrodialysis (ED) plates with precipitated salt.
Apparently, raw water was introduced to the system without prior softening.

     Sludge from the water softening process,  consisting  of calcium and  mag-
nesium salts, is presently taken to the City of Gillette  landfill  for disposal.
Slurry discharged from the softening process is discharged into Stone Pile
Creek (Burlington Ditch) immediately to the north of the  plant creating  a
direct source of potential groundwater pollution.

Landfill or Dumps

     The Gillette landfill is located southwest of the City on a hill.  In
the  southwest corner of the site are stockpiled the so-called "white goods,"
mainly metals such as automobiles, 55-gallon oil drums, discarded tires,
wooden furniture, etc.  North of the metal disposal area is a pit in which
oily wastes  have been dumped, along with some metals.  Pesticide containers
and  wastes are accepted.  Runoff enters this pit from a local area.  Near the
pit  is an area where open burning  is permitted.  Down the hill, on'the north
end, are three long parallel trenches.  Each is about 30 to 40 feet wide, 400
to 500 feet  long and a maximum of  20 to 30 feet deep.  The coal almost extends
up to the land surface and was removed and piled on the sides of each trench.
Surface runoff readily flows into  the trenches and possibly into the buried
solid wastes.

     West of the two lower trenches is another pit, about 100 feet long and
200  feet wide-the so-called dead  animal pit.  South and east of the three
trenches and up  nearer the 2-million gallon City water tank are two additional
pits.  These pits contain oily wastes and septic tank pumpage.  Garbage also
is scattered about.

      South and  slightly up  the  hill  from the  oily waste  ponds is  an area mark-
ed for  "tires only."   Oily wastes  have  also been discharged  into  this area.

      The presence of surface water running  into  the landfill  trenches is ideal
for  the production  of  leachate.   In fact,  leachate plumes in  the  shallow aqui-
fers should  be  considered a definite  possibility.

Urban Runoff

      Urban runoff and  related pollution sources  in the Gillette area include
the  runoff itself,  traffic-associated  pollutants,  and  street and  highway

                                      27

-------
 deicing  salts.   Specific  sources  in  urban  runoff  include settled dust, fly
 solids from off-street  mud,  automotive  exhaust, organic debris from tree
 leaves,  grass  trimming, and  discarded litter  (McElroy et a!., 1976).  Another
 primary  source in  the urban  environment is  fecal  matter from domesticated and
 indigenous  animals.  Motor traffic contributes particulate materials and
 nutrients which accumulate in  the surfaces  of roadways.  Deicing salt is
 applied  to  roadways  during winter and spring  months.

 Miscellaneous  Potential Pollution Sources

      Miscellaneous potential sources of groundwater contamination  in the City
 of Gillette include:  (1) sources relating to recreational activities, e.g.,
 leakage from Gillette  Fishing Lake;  and (2) discharge of sources to washes,
 e.g., road oil leaking  from  containers  near the City of Gillette Treatment
 Plant into Stone Pile  Wash.

 Other Municipalities

      The major population centers outside  the Gillette city limits are:
 Rawhide Village, Collins  Heights, Wyodak Construction Camp, Hidden Valley,
 Westridge, Heritage Village, and  Wright, Wyoming.  Table 2-1 details the
 methods of waste disposal at each of these areas.
TABLE 2-1. OTHER MUNICIPALITIES
Sewage treatment
Development
Rawhide Village
and Trailer Park
Collins Heights
Wyodak Construction
camp
Hidden Valley
Westridge
Wright
Heritage Village
Water supply
Fort Union wells
Fort Union wells
Fort Union wells
Fort Union wells
Fort Union wells
Fort Union wells
Fort Union wells
^••••••••^••••••••••••••(•••••••(••••••••^•••••MMIIH
Sewage effluent
Small , ephemeral
channel
None
Donkey Creek
Small , ephemeral
channel
None
Small , ephemeral
channel
Small , ephemeral
channel
•M«M_WM^^___|H»MIHnMMIMH^^HBHvai|MII
Sewage sludge
Trucked to City
treatment plant
None
Trucked to City
plant
Trucked to City
treatment plant
None
Uncertain
Trucked to City
treatment plant
iWBIHHHHHHIIIflHHIIBHHIIIgHHHIHHVIIV,^H^H^^HHMMHIBHIII
Septic
tanks
None
1 tank/
1 acre lot
None
None
1 tank/
1 acre lot
None
Some in
early sub-
division
(Anderson)
M^M«HWWMV-«*«^HB**l«
Dumps
None
None
None
None
None
None
None
•••^•^^^•^••^^
     Virtually all the water supply  is  from wells  drilled  into the deep Fort
Union aquifers.  The waters are low  total  dissolved  solids (TDS),  sodium
bicarbonate types that are superior  to  the City  of Gillette's  municipal supply.
                                      28

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     Sewage disposal is achieved by package sewage treatment plants or septic
tanks.  Treatment plants are located at Rawhide, Wyodak, Hidden Valley, Heritage
Village, and Wright.  Liquid effluents are discharged into small holding ponds
which empty into local ephemeral channels.  Sewage sludge is, as a rule, truck-
ed to the City of Gillette sewage treatment plant and is disposed with the
City's sewage sludge.  Septic tank areas include Westridge, Collins Heights,
and the Anderson subdivision (adjacent to Heritage Village).

     No dumps or landfills are located at the subdivisions.  Garbage and trash
are collected and hauled to the Gillette-Campbell County landfill.  Plans for
such facilities at Wright, Wyoming, are currently being contemplated.

     Local runoff is uncontrolled and, in all cases, runs downhill to the
nearest stream channel.  Due to the small size of most of these subdivisions,
and also due to their suburban character, the pollution potential of local run-
off is minimal.

     In summary, monitoring programs dealing with the subdivisions should
concentrate on the effluents discharged by the package sewage treatment plants.
Sewage sludge and solid waste are disposed of at City facilities, strengthen-
ing the need for monitoring at these locations.
                                     29

-------
                                   SECTION  3

                             POTENTIAL POLLUTANTS
 AGRICULTURE
      Major potential  pollutants  from the  use of  fertilizers  in Campbell  County
 are nitrogen, phosphorus,  and possibly  potassium.  The major pollutants  asso-
 ciated with livestock in Campbell  County  are nitrates and organic components
 of animal waste.   The major weed killer used is  2,4-D.  Potential groundwater
 pollutants resulting  from irrigation and  leaching  include primarily the  solu-
 ble salts calcium, magnesium, sodium chloride, sulfate, and  bicarbonate; how-
 ever, irrigation is limited in the project area.

 COAL STRIP MINING

 Active Mining Sources

      Active mining sources identified in  this report include stockpiles  con-
 sisting of topsoil, overburden,  coal  ore, coal refuse,'coaly waste, and  part-
 ings.  These materials are discussed in the following paragraphs.

 Topsoil-

      Certain trace elements may  be present in topsoils in the Powder  River
 Basin that can be significant groundwater pollutants.  Summary analyses  of
 trace elements in near-surface materials  in the  Powder River Basin are given
 by the U.S.  Geological  Survey (Keefer and Hadley,  1976).

      Soluble salts that have been  concentrated in  some soil  series are poten-
 tial  water pollutants.   These salts have  been concentrated by ponding and
 evaporation  of runoff,  by  evapotranspiration of  soil moisture, and by lack  of
 leaching in  soils of  low permeability.  Soil salinity values are  given in the
 Eastern Powder River  Coal  Basin  environmental impact statement (EIS)  and in
 some  mine EISs.

      Topsoil  characteristics for four mines are  summarized in Table 3-1.
 Ranges  for the sodium adsorption ratio  (SAR), electrical conductivity, and
 pH along  with  the number of samples analyzed are given.  No  data  are  avail-
 able  for  ARCO  Black Thunder,  Carter North Rawhide, and Kerr-McGee Jacobs
 Ranch mines.

     Major soil series  on  the Eagle Butte lease  were analyzed for boron, cad-
mium, lead, and mercury  concentrations  (see Table  3-2).  In  another analysis
boron was found to range from zero  to 1.01 ppm with an average of 0.47 ppm

                                      30

-------
on Sun Oil's Cordero mine.  Selenium  found at the Wyodak mine  ranges  from  less
than 0.01 to 0.06 ppm averaging 0.01  ppm with boron concentrations between 0.2
and 2.0 ppm averaging 0.81  ppm.  Trace element analyses are not available  for
the other mines.
              TABLE 3-1.  SITE-SPECIFIC TOPSOIL CHARACTERISTICS
Mine
AMAX Belle Ayr South
AMAX Eagle Butte
Sun Oil Cordero
Wyodak
Sodium
jnin.
0.2
0.3
0.18
0.5
adsorption ratio Conductivity
max. ave. min. max. ave.
7.5
5.1
16.18
8.9
2.62
2.19
5.62
5.0
0.13
0.13
0.13
0.0
1.53
-
21.3
2.18
0.81
1.04
5.68
0.052
min.
7
7
6
7
.2
.6
.2
.3
PH
max.
8.1
8.2
8.2
9.2
Number of
ave. samples
7.6
7.95
7.6
8.4
86
20
58
43

   Conductivity measured in mmhos/cm.
          TABLE 3-2.  CONCENTRATIONS (ppm) OF TRACE ELEMENTS BORON,
                      CADMIUM, LEAD, AND MERCURY IN SOILS ON THE
                      EAGLE BUTTE MINE PROPERTY


Terry series
Vona series
Maysdorf series
Renohill series
Bidman series
Goshen series
Arvada series
Shingle series
B
0.18
0.12
0.08
0.29
0.25
0.48
1.94
0.13
Cd
0.52
0.52
0.50
0.66
0.53
0.57
0.56
0.54
Pb
1.95
1.99
2.36
2.65
2.00
1.81
3.28
2.44
Hg
0.27
0.31
0.39
0.36
0.18
0.32
0.40
0.58

Overburden-

     As is the case with topsoil, a potential water pollutant in overburden is
soluble salts.  For example, the soluble salt content of six overburden sam-
ples from the Sun Oil Company Cordero mine ranged from 0.04 to 0.88 percent by
weight (Dames and Moore, 1974).  Using these values, and an assumed dry weight
of 1.5 tons per cubic yard for overburden, there would be from 1.2 to 26.4
pounds of soluble salt per cubic yard.  Each acre-foot of overburden contains
1,613 cubic yards.  Therefore, each acre-foot of overburden might contain from
1,936 to 42,583 pounds of soluble salts.


                                     31

-------
      The possibility of trace  elements  in the overburden becoming important
 groundwater pollutants  has  been  and  still is of concern.  Because of this,
 trace element analyses  have been performed on overburden from most, if not
 all, of the Powder River Basin mines that now exist or are under active devel-
 opment.  The significance of the analyses remains to be interpreted.

      Analysis of conductivity, sodium adsorption ratio, cation exchange capac-
 ity, pH, and trace elements from cores  of the overburden taken throughout the
 study area are summarized in Table 3-3.  Trace element analyses also are
 available for ARCO Black Thunder and Wyodak mines.

      Electrical  conductivity (EC) maximum values range from 4.2 to 8.0 micro-
 mhos per centimeter (mmhos/cm) throughout the study area.  Values less than
 8.0 mmhos/cm are indicative of only  moderately saline conditions (Wiram, nd).
 High EC values are found for samples taken within 5 feet of the surface on the
 Belle Ayr South mine.   For  deeper overburden, salt concentrations are usually
 less than 2.0 mmhos/cm  which is  considered to be insignificant (Wiram, nd) and
 would have negligible effect on  plant growth.

      The major anions responsible for the observed EC values on the Eagle
 Butte lease are, in order of abundance:  sulfate, chloride, bicarbonate, and
 nitrate.  The major source  of  sulfate is gypsum and epsomite (MgS04~FH20).
 Sodium chloride and other evaporites are sources of chloride and calcium
 carbonate and complex carbonate  sulfates are sources of bicarbonate.  Soluble
 nitrates may be formed  by the  nitrification of exchangeable ammonium nitrogen
 (Power et al., 1974).

      High SAR values were also found in the uppermost 5 feet.  The maximum
 value was 17.6.   According  to  Wiram  (nd), SAR values greater than 12.0 indi-
 cate potential problems  in  permeability and structural stability.  They are
 indicative of an imbalance  between sodium and calcium plus magnesium ions
 within the montmorillonite  clay,  which reduces permeability to practically
 zero.   For deeper overburden,  SAR values average 3.5, indicating that the clay
 minerals are saturated  with calcium  and magnesium.  Shales and mudstones, in
 general, were found to  have slightly higher SAR values than associated sand-
 stones.

      High cation exchange capacity (CEC) values were found for all shales and
 mudstones.   The  average  is  16.8  milliequivalents per 100 grams (meq/100 g)
 with a maximum value greater than 30 meq/100 g.  These values reflect a high
 content of montmorillonite  clay.  CEC values for unconsolidated sands and
 sandstones  are considerably lower, averaging 8.5 meq/100 g.

     Wiram  (nd)  suggested that continued surveillance will be required if any
 irrigation  is  done  during revegetation of stockpiled or backfilled overburden.
 Without  the use  of  proper soil  amendments, toxic saline and soil permeability
 problems can be  anticipated.

     Almost all of  the overburden samples were found to have a pH greater
than 7, with the values ranging from  3.6 to 8.7.  Wiram (nd) states that a  pH
greater than 8.2 could result  in an  undesirable soluble carbonate content and
low solubility of calcium salts.


                                      32

-------
                                  TABLE  3-3.   SITE-SPECIFIC  OVERBURDEN CHARACTERISTICS
CO
CO

Mine
AMAX Belle Ayr South
AMAX Eagle Butte
ARCO Black Thunder
Carter North Rawhide
Kerr-McGee Jacobs Ranch
Sun Oil Cordero
Wyodak

No. of Conductivity3 SAR CECb pH Elementsc
samples Min. Max. Avg. Min. Max. Avg. Hin. Max. Avg. Hin. Max. Avg. Cd Hg Pb Zn Ni Cu S As Se
74 - 6.2 - - 17.6 3.5 - 30.0 16.8 5.3 8.2 0.23 0.08 --1.0 	
92 - 6.5 3.3 12.8 36.0 27.5 5.0 8.5 0.17 0.05 0.43 	
41d 	 	 3.44 0.12 35 - - 33.8 - 0.8
11 0.7 4.2 1.9 - - 13.033.0 7.4 8.7 ----- 1.7 168 -
55 0.5 5.5 - - - 11.0 32.0 22.7 7.8 8.4 ----- 0.88 167 -
89 0.5 8.0 - 0.3 7.2 - 3.9 48.4 - 3.6 - 0.1 0.07 4.3 14.8 2.1 : - -
7d 	 	 0.47 487 <0.1

        Conductivity in mmhos/cm
        Cation exchange capacity meq/100 g
       ""Average concentrations in ppm
        Trace element analysis only

-------
      Five overburden samples from Belle Ayr South were found to have a total
 sulfur  content greater than 1.0 percent, with the others rarely exceeding 0.3
 percent.  Of the five samples, two contained fine-grained pyrite and others
 had  large amounts of gypsum and carbonaceous matter.   Gypsum crystals and
 soluble sulfate salts are the major sources of sulfur in the overburden.   Sul-
 fate  concentrations were found to range from 20 to 40 meq/liter.  It is
 present primarily in the form of the mineral selenite (CaS04 •  21^0).

      A  potential problem of trace element concentrations of cadmium  and
 mercury may arise.  Several examples are shown in Table 3-3 and exceed
 natural background levels.  Other trace element concentrations  are summa-
 rized in Table 3-3.  Arsenic was found on the Black Thunder lease ranging
 from  less than 0.05 to 7.75 ppm, averaging 0.80 ppm.   Selenium  was found
 in concentrations less than 0.1 ppm for all  samples taken on the Wyodak
 mi ne.

 Coal, Coal Refuse, and Coaly Waste-

      Coal, coal refuse, and coaly waste probably contain some soluble salts,
 although no analysis of the soluble salt content of these materials  has been
 found in the literature or in unpublished reports.  The soluble salts are
 expected to be principally in the form of crystals  of gypsum or similar miner-
 als formed in open fractures.   Intergranular pores  are not present in the coal
 and coaly strata as they are in the rest of the overburden.

      Sulfur is universally found in coal and carbonaceous strata, but in  dif-
 ferent  forms and in varying amounts of those forms.  The two general  forms of
 sulfur  that occur in and with coal  are inorganic sulfur and organic  sulfur.
 Inorganic sulfur occurs primarily as pyrite or marcasite, which are  both
iron disulfide (FeS2).

      Acid drainage from coal strip mines is an important problem in  eastern
 coal  mining states, but has not been recognized as a  serious problem in most
 western coal mining areas.  One of the characteristics of Powder River Basin
 coals is the low sulfur content.  This  is probably the reason that acid
 drainage has not been a problem in the area.  However, some pyrite oxidation
 does  occur as is evidenced by the spontaneous combustion of coal piles along
 the base of the high wall of the Wyodak mine.  Apparently the acid that does
 form  from oxidation of pyrite in Powder River Basin coal and associated car-
 bonaceous strata is rapidly neutralized, probably by carbonate minerals  in the
 soil  and overburden, and does not cause measurable lowering of  the pH  of  sur-
 face  water and groundwater.  It will, however, contribute dissolved  solids in
 the form of sulfates, probably principally calcium and magnesium.  The acid
 that  is formed might also dissolve some trace metals before  it  is neutralized.
As far  as is known, no studies have been made of the amount  of  acid  formed in
 Powder  River Basin strata as a result of coal strip mining  and of the fate of"
 the acid that is formed.

     A  number of measurements have been made of the trace  elements  in Powder
River Basin coals.  Keefer and Hadley  (1976) presented  a  summary of  analyses
of 15 coal samples from the Wyodak mine and 11  samples  from the Belle Ayr


                                    34

-------
mine.  A few trace elements  are  present in coals in amounts greater than  in
the overburden and the earth's crust as a whole, but these trace elements
have not yet been identified as  actual  water pollutants so far as is known.
Trace element and sulfur content of coal  samples are summarized in Table  3-4.


     TABLE 3-4.  SULFUR AND  TRACE ELEMENT CONCENTRATIONS IN COAL SAMPLES
Sulfur
<*)
AMAX Belle Ayr South3
AMAX Eagle Butteb
ARCO Black Thunder0
Carter North Rawhide0
Kerr-McGee Jacobs Ranch0
Sun Oil Cordero
Wyodak0
0.
0.
0.
0.



25-0. 6e
14-1. Oe
09-0. 59e
28-0. 52e
1.06
0.30
0.59
Cd
0

0

<0
0
.1
-
.36
-
.001
.66
0.1-0.16f
Average trace element 
-------
 Explosives—

      The  primary  potential pollutants from explosives appear to be ammonia-
 nitrogen, nitrate-nitrogen, fuel oil, and possibly trace organics.

 Pit  Discharge—

      The  potential  pollutants in pit discharge originate from a number of
 sources.  All of  the  potential pollutants from explosives can be in the pit
 discharge,  namely,  ammonium-nitrogen, nitrate-nitrogen, fuel oil, and trace
 organics.   Most of  the major inorganic chemical constituents and some trace
 elements  can originate from groundwater percolating through the coal, over-
 burden, and underlying beds.  At the Decker Mine, in Montana, high contents of
 sodium, bicarbonate,  and  sulfate were found in pit discharge.  Calcium, mag-
 nesium, chloride, boron,  and fluoride are additional potential pollutants.
 At the  Big  Horn Mine, high contents of iron, manganese, zinc, and copper were
 found in  pit discharge.   Cadmium, chromium, arsenic, lead, molybdenum, vana-
 dium, uranium, thorium, radium, and selenium are additional potential pollu-
 tants.  Organic materials from the coal and related beds also comprise
 potential pollutants.

      Gasoline and oil can be introduced by heavy equipment working in the pit.
 Bacteriological pollutants can be introduced from domestic wastewater, runoff,
 and  solid wastes  disposed of in or near the pits.

 Supplemental Sources  of Water—

      As discussed in  the  pollution source inventory, Section 2, no pollution
 is anticipated from deep  groundwater.  The mines are using water from the
 deeper  part of the  Fort Union Formation, and quality is not a problem.  Use
 of Fox  Hills water  by the City of Gillette could introduce small amounts of
 fluoride  into shallow systems, but the relative volume of Fox Hills water used
 in the  project area is minimal.

 Imported Sewage Effluent—

      The principal  source of imported sewage effluent is from the City of
 Gillette Treatment  Plant.  At the present time (summer 1977) construction is
 being completed on  a pipeline to transport effluent to the Wyodak Mine.
 Effluent will be delivered from two locations:  (1) from the line leading into
 the  "oxidation" pond from the aerobic digesters; and (2) from the "oxidation"
 pond  discharge line.  Wastewater imported into the Wyodak Mine will  be a  blend
 of these sources.  At the present time, effluent discharged into Donkey Creek
 from  the oxidation  pond is diverted at Wyodak for road spraying.  The  RO  unit
 at the Neil Simpson power plant will drastically alter the quality of  effluent
 piped to Wyodak.

      A representative analysis of wastewater from the treatment  plant  is  not
available at this time.  As an approximation, the analysis on Table  3-5 was
developed assuming:    (1) wastewater is essentially of the  same quality as
 incoming sewage because treatment is minimal; (2) composition of medium-
strength domestic sewage reported by Metcalf and Eddy  (1972)  are applicable;


                                      36

-------
and  (3) analysis of carrier water is similar to that for Gillette domestic
water reported by Nelson et al. (1976).  This latter assumption neglects
infiltration/inflow (I/I) in the Donkey Creek line and changes in salt content
as a result of domestic usage.


           TABLE  3-5.   HYPOTHETICAL  QUALITY  OF WASTEWATER FROM THE
           	GILLETTE TREATMENT  PLANT	
                                                    Concentration
           Constituent	(ppm)
Suspended solids, total
Fixed
Volatile
BOD (5-day)
TOC
COD
Nitrogen (total as N)
Organic
Free ammonia
Nitrites
Nitrates
Phosphorus (total as P)
Organic
Inorganic
Alkalinity (as CaC03)
Grease
Potassium
Calcium
Magnesium
Sodium
Sulfate
Chloride
Bicarbonate
TDS
200
50
150
200
200
200
40
15
25
0
0
10
3
7
100
100
9.5
305
158
220
920
36
660
1888

     The constituents and related concentrations in Table 3-5 are possibly
representative of wastewater entering the "oxidation" pond from the aerobic
digesters.  As indicated above, this water will  also be diverted to wyodak.
High total organic carbon (TOC) and chemical  oxygen demand (COD) [as well  as
high 5-day biochemical oxygen demand (BOD)] values indicate that organics
are a potential contaminant.  However, during pipeline flow some additional
breakdown of organics may occur.  Other constituents beyond desirable limits

                                    37

-------
  include sulfate, nitrogen, IDS, and grease.  Flow in the pipeline may  be
  conducive to nitrification, in which case nitrite values niay increase.  The
  wastewater may contain excessive levels of coliform organisms (including
  fecal), viruses and other intestinal organisms.

      Heavy metal concentrations may not be excessive because such metals  tend
  to concentrate in the sludge.

      Observation of the "oxidation" pond at the Gillette Treatment Plant
  shows that the pond actually functions as an overloaded facultative pond
  with operating characteristics of an anaerobic  lagoon.   Consequently, waste-
  water undergoes anaerobic digestion.  According to the  Missouri  Basin  Engineer-
  ing Health Council (1971), anaerobic lagoons are capable of reducing BOD
  levels between 60 percent to 80 percent.  However, "high concentrations of
  BOD, suspended solids, and sometimes hydrogen sulfide occur in  the effluents
  depending upon the initial characteristics of the incoming  wastewaters"
  (Missouri  Basin Engineering  Health  Council,  1971).   It  is highly  probably that
 the pond at Gillette  is  a  poorly operating anaerobic  facility.  However,  if
 the treatment effectiveness  is  similar to a  pond in  Saskatchewan  (reported by
 the Missouri  Basin Engineering  Health  Council,  1971), the following  removal
 efficiencies  may exist:   suspended  solids, 70 percent;  BOD,  55 percent; COD,
 60 percent;  and grease,  75 percent.  Using these efficiencies and the corres-
 ponding values  in Table  3-5,  resultant effluent concentrations may be:  BOD,
 90 ppm;  COD,  200 ppm;  and  grease, 25 ppm.   The  chemical  constituents will
 remain  about  the same, although some change  in  sulfate  should occur  due to the
 formation  of  hydrogen  sulfide (H2S).   Also,  because  of  anaerobic  conditions,
 nitrogen constituents  will  remain about the  same concentration.   The presence
 of bacterial  colonies  floating  on the  surface on the  pond suggests the pond
 effluent contains organisms  such as  coliform bacteria,  viruses, and  parasitic
 organisms.   Reducing condition  promotes the  mobility  of heavy metals which may
 have escaped  the chelating effects  of  sludge constituents.

      Since  the  pond effluent  will be diverted to Wyodak in  a pipeline, mixing
 will  occur with wastewater diverted  from the pond inlet line.  Also, some
 decomposition will occur in  the line,  reducing  COD and  BOD  (organics) some-
 what and possibly promoting nitrification.

 Mine  Sanitary Wastes-

      Septic tanks-Septic tanks reduce the BOD and solids content of sewage
 but not necessarily the  loading of microorganisms and viruses.  Discharge
 from a septic tank (to a leach  field)  contains  nutrients, salts,  and suspend-
 ed solids.  Table 3-6, reproduced from a paper  by Silberman (1977),  is a
 representative analysis of septic tank effluent concentrations.   The COD  and
 TOC values suggest that organics might be moderately high in effluent.  Also
 note the concentration of total  coliform organisms.   No information is avail-
 able on heavy metals,  but presumably metals  in  the carrier  water  will  settle
with sludge in the tank or be carried  out with  suspended solids.

     Further treatment occurs in the leaching field,  two conditions are
possible:  (1) if the  field is  overloaded and in tight  soils, anaerobic con-
ditions may result; (2) if good air  circulation prevails, the leaching field

                                     38

-------
 will  remain aerobic.   The  state  of aeration  may  have an effect on sources.
 Aerobic conditions  will  increase nitrate  levels  in wastewater but lead to a
 stabilization of organics  and destruction of obligate anaerobics.


        TABLE 3-6.  REPRESENTATIVE SEPTIC  TANK  EFFLUENT CONCENTRATIONS
                    AND PERCENT REMOVED  (Silberman, 1977)
       Parameter
Value'
Percent removed
 or increased
pH (units)
Dissolved oxygen
Biochemical oxygen demand
Chemical oxygen demand
Total organic carbon
Total phosphorus
Phosphates
MBAS
Total solids
Total suspended solids
Total nitrogen as N
Ammonia nitrogen
Organic nitrogen
Nitrate
Nitrite
Chlorides
Alkalinity
Col i forms - total (105/100 cc)
- fecal
7.1±
0
160
323
129
18
34
7.6
378
90
32
27
8
0.14
0.061
95
390
11-110+
0.17
—
—
27
47
46
40
240 increase
67
46
70
8
8 increase
20
increase
increase
111 increase
225 increase
—
—

         Units  are  ppm except as noted.
     Anaerobic decomposition of septic tank effluent may reduce nitrate levels
(assuming that nitrification has occurred).  Anaerobiosis and associated reduc-
ing conditions may lead to production of methane and hydrogen sulfide gases,
carbon dioxide, and volatile compounds of mercury (Hg) and arsenic (As)
(Fuller, 1977).  Hydrogen sulfide (I^S) is reactive with heavy metals as sul-
fides of iron (FeS), zinc (ZnS), cadmium (CdS), lead (PbS), copper (CuS), and
mercury (Hg2$ or HgS).  Reducing conditions increase the mobility of the
majority of trace contaminants (Fuller, 1977).  For example, reduced iron
becomes soluble and highly mobile.

                                     39

-------
      Organic acid production increases under anaerobic conditions    The
 resultant lowering of pH will increase the mobility of cationic heavy metals.
 In addition, chelation will also promote the movement of heavy metals and
 soluble organics.

      In summary, aerobic leach fields are possible sources of nitrate, ammo-
 nia, phosphorus, potassium, chloride, any heavy metals present in abundance,
 organics, bacteria, and viruses.  Anaerobic leach fields may also be sources
 of these constituents but the characteristics of the source would show the
 effect of anaerobic conditions on the solubility of indigenous heavy metal
 compounds,  including those of lead, iron, manganese, copper, and mercury.

      Package plants-The types  and  importance of  potential  pollutants associ-
 ated with package plant effluent are the same as those for septic tanks
 (Todd et al., 1976).  A representative analysis of effluent from package
 plants, reported by Silberman (1977) is shown in Table 3-7.  This analysis
 does not include other chemical parameters which may be high in effluent,
 including sulfate, chloride, hardness, bicarbonate, calcium, and possibly
 trace metals.   Viruses may also be present in the effluent.


      TABLE  3-7.  AEROBIC TANK EFFLUENT CONCENTRATIONS (Silberman, 1977)


           Parameter	Val ue	

           pH  (units)                              7.7
           Dissolved oxygen                        2.76
           Biochemical oxygen demand              41
           Chemical oxygen demand                158

           Total organic carbon                   40
           Phosphates  (as P)                      37
           Total suspended solids                 57

           Nitrate .(as" N)                          8
           Nitrite  (as N)                          2
           Coliforms (105/100 cc)                 72

           aUm'ts are  ppm except as noted.
     Operation of package plants may require the removal of solids at  infre-
quent intervals.  Solids will consist mainly of grit, with perhaps some plas-
tic and other organic matter.

     Treatment ponds—The design and operation of waste treatment ponds is
such that quality varies laterally from inlet to outlet and vertically from
water surface to the benthic layers.  In general, the overall quality  is a

                                     40

-------
function of loading rate, temperature, hours of sunshine, wind action, etc.
Quality is also a function of the type of pond operation, e.g., aerated
pond, anaerobic pond, or facultative pond.

     According to the publication, "Waste Treatment Lagoons-State  of  the
Art," by the Missouri Basin Engineering Health Council (1971), aerated lagoons
are capable of meeting the 30 ppm BOD, 30 ppm suspended solids criteria of
EPA.  However, aerated lagoons are not very efficient in removing nitrogen
and phosphorus.  The reason is that aerated lagoons operate on the principle
that solids are not removed.  Potential pollutants, therefore, comprise some
unstabilized organics, phosphorus and nitrate, and bacteria and viruses, as
well as heavy metals introduced with the raw sources.  Metals will  concen-
trate in the sludge.

     Anaerobic lagoons are not normally effective for secondary treatment,
and effluents could lead to pollution (Missouri Basin Engineering Health
Council, 1971).  Effluent quality depends on the source of wastewater, but
BOD concentrations of 100 ppm to 300 ppm have been observed in anaerobic
lagoon effluents from domestic sources.  The ratio of discharged effluent to
incoming wastewater BOD values ranges from 0.40 to 0.70.   Nutrients are not
appreciably reduced in anaerobic lagoons.  For example, incoming organic-N
and NH^-N are not nitrified, although incoming nitrate may be denitrified.

     In addition to potential pollutants within the wastewater itself,
anaerobic lagoons may potentially release pollutants present in the benthic
region soil.  That is, anaerobic and reducing conditions  may increase the
solubility of cationic heavy metals in the soil.  Sources related to anaero-
bic lagoons will include incoming nutrients and other chemical constituents
(chloride, sulfate, bicarbonate, carbonate, calcium, magnesium, sodium, etc.)
and organic-N, organic-P, ammonia and phosphorus compounds, bacteria,  and
viruses.

     Facultative ponds may not attain the required standard:  30 ppm BOD, 30
ppm suspended solids, and 200 coliform per 100 cubic centimeters (cc).  BOD
is transformed from incoming organics into algal tissue,  and suspended solids
reflect algal concentrations.  Algae are capable of reducing nutrients and
heavy metals which, however, are released with the death  and lysing of algal
cells.  Because of algal activity, the pH of lagoon water increases, with
concomitant alteration of the bicarbonate-carbonate system.  The dissolved
oxygen in overlying layers may become supersaturated, while oxygen deficiency
and anaerobic conditions prevail  in the benthos.  An abundance of dissolved
oxygen (DO) in the upper part of the pond presents optimal  conditions  for
nitrification.  In addition, reactions with soil material  (see above)  may
lead to generation of heavy metal  sources.   Also,  under very cold or freezing
conditions, such as occur in the Gillette area, facultative ponds may  become
anaerobic, producing sources discussed above.

     For normal  operation, the potential pollutants relating to facultative
ponds include BOD (organics), suspended solids (organics), chemical constitu-
ents in incoming carrier water, nitrate (some of which is reduced to nitrogen
gas in the benthos), a flourishing bacteria population, and viruses.  In
addition,  heavy metals may be generated in the anaerobic  and reduced benthic-
soil  interface.

                                     41

-------
     Two mines planning to use pond pretreatment are the Wyodak  mine,  where
an aerated sewage lagoon will  be used (no data are available on  expected
quality) and the AMAX Belle Ayr South mine, where a "lagoon type aeration
plant" will be used.  The only information on quality of the pond system
reported in the EIS (U.S. Department of Interior, 1975)  is:  "Effluent will
meet...standards such as pH, iron, manganese, and TDS."   A sand  filter will
reduce suspended solid concentrations.

Solid Wastes-

     Solid waste management offers the following options:

          •  Onsite landfill
          •  Offsite disposal  facility
          •  Incorporation in mine spoils
          •  Incineration followed by land disposal of residue.

      Onsite landfills comprise special  areas set aside on the mine specifically
for  landfills; offsite disposal facilities may consist of a central landfill,
such as  that operated by the City of Gillette; and incorporation in mine
spoils  is  self-explanatory.  Both onsite and offsite disposal facilities  are
centralized and allow more control.  Wastes incorporated in the spoils piles
will  be  distributed randomly, without control on the amount or nature of
wastes.   Incineration may create pollutants relating to flyash or gas genera-
tion as  well as producing concentrated solid waste.

      In  general, no matter how disposed, solid wastes will contain the same
potential  pollutants.  According to Todd et al. (1976), major types of ground-
water pollutants associated with solid wastes include:

             Physical — Minor
             Inorganic chemicals - Primary
             Trace elements — Primary
             Organic chemicals - Primary
             Bacteriological - Minor
             Radiological - Minor.

      Some  sources present in landfills are reflected in leachates, generated
by the action of water with solid wastes.  The range in leachate quality,
such as  found in municipal landfills, is shown in Table 3-8 as reported  by
Pohland  and Engelbrecht  (1976).  These authors point out that leachate is most
objectionable from a pollution viewpoint when containing high concentrations
of organic matter, high TDS, and low pH.  Decreasing pH increases  the solubil-
ity  of heavy metals present in the waste.  In addition, anaerobic  reducing
conditions in the soil-landfill interface will also dissolve indigenous  heavy
metals.  Microbial (and virus) growth in leachate appears  to be  inhibited by
initial  elevated temperature and other inactivating properties.

     The quality of leachate changes with time because of  changes  in  composi-
tion of  substrate and biological communities.  Consequently, high  organic
concentrations in the leachate will disappear, pH will return to neutral and
leachate will be less objectionable from the viewpoint of  organics.   Changes


                                    42

-------
TABLE 3-8.  RANGE OF CHEMICAL COMPOSITION OF SANITARY LANDFILL
            LEACHATE (Pohland and Engelbrecht,  1976)

Constituent
Chemical oxygen demand
5-day biochemical oxygen demand
Total organic carbon
pH (units)
Total solids
Total dissolved solids
Total suspended solids
Specific conductance (ymho/cm)
Total alkalinity (as CaC03)
Total hardness (as CaCO^)
Total phosphorus (as P)
Orthophosphorus (as P)
Ammonia nitrogen (as N)
Nitrate + nitrite (as N)
Calcium
Chlorine
Sodium
Potassium
Sulfate
Manganese
Magnesium
Iron
Zinc
Copper
Cadmium
Lead
Range of
40
81
256
3.7
0
584
10
2,810
0
0
0
6.5
0
0.2
50
4.7
0
28
1
0.09
17
0
0
0
< 0.03
< 0.10
analyses3
- 89,520
- 33,360
- 28,000
- 8.5
- 59,200
- 44,900
- 700
- 16,800
- 20,850
- 22,800
- 130
- 85
- 1,106
- 10.29
- 7,200
- 2,467
- 7,700
- 3,770
- 1,558
- 125
- 15,600
- 2,820
- 370
- 9.9
- 17
- 2

Values are in ppm unless otherwise noted
                               43

-------
 in  inorganics are less predictable.  Pohland and Engelbrecht (1976) point out
 the danger of extrapolating the environmental impact of leachate based on
 single  sample analyses.

      In addition to municipal-type wastes, hazardous wastes from mines may be
 disposed of  in landfills.  Information on specific hazardous wastes is not
 available at this time.  As an initial approximation, Table 3-9 [reproduced
 from  "Decision Makers Guide in Solid Waste Management," (U.S. Environmental
 Protection Agency, 1976b)] is included.  This table is a sample list of non-
 radioactive  hazardous compounds which can be considered as hazardous to public
 health  and the environment.

      Incineration followed by landfilling is an alternative waste disposal
 technique.   Pavoni et al. (1975) review the general principles and methods
 employed in  municipal incineration operations.  Similarly, Scurlock et al.
 (1975)  discuss requirements and precautions for incineration of hazardous
 wastes. Incineration releases gases and particulate matter to the atmosphere
 unless  trapped and scrubbed.  Waste gases may contain nitrogen, carbon diox-
 ide,  and water vapor.  During periods of incomplete combustion, the following
 gases may be present:  nitrogen dioxide, nitric oxide, sulfur dioxide, sulfur
 trioxide, and carbon monoxide (Pavoni et al., 1975).  Acids or other com-
 pounds  may be formed during reaction of rainwater with these gases.  Chlorine
 containing organics may  emit hydrogen chloride gas upon incineration which is
 highly  corrosive (Scurlock et al., 1975).

      Fly ash produced in municipal refuse incinerators is largely inorganic
 and consists of oxides of aluminum, calcium, iron, and silicon (Pavoni e't al.,
 1975).  A chemical analysis of incinerator fly ash is reproduced in Tables
 3-10  and 3-11.

      Incinerator residue contains soluble organic and inorganic constituents.
 Although a complete analysis by constituents was not presented, Pavoni et al.
 (1975)  gave  the general  breakdown shown in Table 3-12.  Scurlock et al.
 (1975)  noted that organic materials may contain such heavy metals as mercury,
 arsenic, selenium, lead, and cadmium.  These heavy metals may exist as oxides
 in  the  ash.  "Landfilling of the ash...should be examined with care to ensure
 that  health  hazards or environmental degradation do not occur due to leach-
 ing of  toxic metal  ions to subsurface waters	" (Scurlock et al., 1975)

      Fly ash may be treated with water to facilitate transportation to a
 final disposal  site.   The slurry will contain undesirable constituents, such
 as  heavy metals.   Table 3-13, reproduced from Pavoni et al. (1975), shows
 representative wastewater data from the incineration process.

      Information on solid waste management was given for the following mines
 in  the  project area,  in the associated environmental impact statements.

     Solid  wastes may be buried at the Kerr-McGee Jacobs Ranch mine.   Possi-
ble contaminants  in leachate are shown in Table 3-8.
                                    44

-------
TABLE  3-9.   A SAMPLE  LIST OF NONRADIOACTIVE  HAZARDOUS COMPOUNDS
               (U.S.  Environmental  Protection Agency,  1976b)
   Miscellaneous Inorganics
   Ammonium chromate
   Ammonium dichromate
   Antimony pentafluoride
   Antimony trifluoride
   Arsenic trichloride
   Arsenic trioxide
   Cadmium (alloys)
   Cadmium chloride
   Cadmium cyanide
   Cadmium nitrate
   Cadmium oxide
   Cadmium phosphate
   Cadmium potassium
     cyanide
   Cadmium (powdered)
   Cadmium sulfate
   Calcium arsenate
   Calcium arsenite
   Calcium cyanides
   Chromic acid
   Copper arsenate
   Copper cyanides
   Cyanide (ion)
   Decaborane
   Diborane
   Hexaborane
   Hydrazine
   Hydrazine azide
   Lead arsenate
   Lead arsenite
   Lead azide
   Lead cyanide
   Magnesium arsenite
   Manganese arsenate
   Mercuric chloride
   Mercuric cyanide
   Mercuric diammonium
     chloride
   Mercuric nitrate
   Mercuric sulfate
   Mercury
   Nickle carbonyl
   Nickle cyanide
   Pentaborane-9
   Pentaborane-11
   Perchloric acid (to 72%)
   Phosgene (carbonyl
     chloride)
   Potassium arsenite
   Potassium chormate
   Potassium cyanide
Potassium dichromate
Selenium
Silver azide
Silver cyanide
Sodium arsenate
Sodium arsenite
Sodium bichromate
Sodium chromate
Sodium cyanide
Sodium monofluoro-
  acetate
Tetraborane
Thallium compounds
Zinc arsenate
Zinc arsenite
Zinc cyanide

Halogens and Interhalogens
Bromine pentafluoride
Chlorine
Chlorine pentafluoride
Chlorine trifluoride
Fluorine
Perchloryl fluoride

Miscellaneous Organias
Acrolein
Alkyl leads
Carcinogens (in general)
Chloropicrin
Copper acetylide
Copper chlorotetrazole
Cyanuric tri azide
Diazodinitrophenol
  (DDNP)
Dimethyl sulfate
Dinitrobenzene
Dinitro cresols
Dinitrophenol
Dinitrotoluene
Dipentaerythritol
  hexanitrate (DPEHN)
GB (propoxy (2)-
  methylphosphoryl
  fluoride)
Gelatinized nitro-
  cellulose (PNC)
Glycol dinitrate
Gold fulminate
Lead 2,4-dinitroresor-
  cinate (LDNR)
Lead styphnate
Lewisite (2-chloro-
  ethenyl dichloroar-
  sine)
Mannitol hexanitrate
Nitroaniline
Nitrocellulose
Nitrogen mustards
  (2,2',2" trichloro-
  triethyl amine)
Nitroglycerin
Organic mercury
  compounds
Pentachlorophenol
Picric acid
Potassium dinitrobenz-
  furoxan (KDNBF)
Silver acetylide
Silver tetrazene
Tear gas (CN)(chloro-
  acetophenone)
Tear gas (CS)(2-chloro-
  benzylidene malo-
  nonitrile)
Tetrazene
VX (ethoxy-methyl phos-
  phoryl N,N dipropoxy-
  (2-2), thiocholine)

Organic Halogen Compounds
Aldrin
Chlorinated aroma tics
Chlordane
Copper acetoarsenite
  2,4-D(2,4-dichloro-
  phenoxyacetic acid)
DDD
DDT
Demeton
Dieldrin
Endrin
Ethylene bromide
Fluorides (organic)
Guthion
Heptachlor
Lindane
Methyl  bromide
Methyl  chloride
Methyl  parathion
Parathion
Polychlorinated-
  biphenyls  (PCB)
                                      45

-------
         TABLE 3-10.   CHEMICAL ANALYSIS OF INCINERATOR FLY  ASH
                       (Pavoni  et al.,  1975)
-
Component
Carbon
Organic
Inorganic
Silicon as SiO«
Si
w 1
Aluminum as AlJk
Al c *
Iron as Fe,0,
Fe
Sulfur as SO,
S 3
Calcium as CaO
Ca
Magnesium as MgO
Mg
Titanium as Ti07
Ti
Ni

Na

Zn

Ra

Cr

Cu

Mn

Sn

B
Pb

Be
Ag

V
IT - -
Gansevoort
incinerator,
New York City3
(% by weight)

14.5
85.5
36.0
27.7
10.0
9.7
-
8.5
-
3.4
.
_
_

_

.

_

-

-

-

-

-
-

-
-

-
— ^ — ~—
South Shore
incinerator, Arlington,
New York Citya VAa
{% by weight) (%)

10.4 11.62
89.6
36.1
18.64
22.4
10.79
4.2
2.13
7.6 Small or
trace
8.6
4.70
2.1
0.98
-
2.24
Small or
trace
Small or
trace
Small or
trace
Small or
trace
Small or
trace
Small or
trace
Small or
trace
Small or
trace
- -
Small or
trace
-
Small or
trace
- -
Jens-Rehm Kaiser
study b study0

-
5+
1-10
0.5-8.0
""
*•
—
1.0+
1-10
~
0.5-5.0
1-10

1-10

1-10

0.1-1.0

0.1-1.0

0.1-1.0

0.1-1.0

0.05-0.5

0.01-0.1
0.01-0.1

0.001-0.01
0.001-0.01

0.001-0.01

-
36.3
t
25.7
7.1
8.0
-
8.8
-
2.8
Of\
.9
-
-

-

-

-

-

-

-

-

-
-

-
-

—

Sources:

 a Municipal  Refuse Disposal.  Inst.  for Solid  Wastes, Amer. Public Works Assn.,
   1970.

 b Jens,  W.,  and F.R. Rehm.  Municipal  Incinerator and Air Pollution Control.
   Proc.  Nat'l. Incin. Conf., Amer.  Soc. Mech.  Eng.,  1966, p. 74.

 c Kaiser,  E.R.  Refuse Composition  and Flue-Gas Analyses from Municipal
   Incinerators.  Proc. Nat'l. Incin. Conf.,  Amer. Soc. Mech. Eng., 1964, p. 35.

                                    46

-------
 TABLE  3-11.
CHEMICAL ANALYSIS OF INCINERATOR  FLY  ASH
(Pavoni  et  al.,  1975)

Component
Sodium and potassium
oxides
Na as Na,0
Na i

K

Ga

Hg

Mo

Ta

Apparent specific
gravity
Ignition loss
Gansevoort
incinerator,
New York City*
(% by weight)

4.7
-
-

-

-

-

-

-

2.58

"
South Shore
incinerator, Arlington,
New York City3 VA»
(% by weight) (%)

19.0
-
Small or
trace
Small or
trace
Small or
trace
Small or
trace
Small or
trace
Small or
trace
-

14.45
Kaiser
studyb
(%)

.
10.4
-

-

-

-

-
,
-

-

"
 Sources:

  a Municipal Refuse Disposal.  Inst. for Solid Wastes, Amer.  Public Works
    Assn., 1970.

    Kaiser, E.R.  Refuse Composition and Flue-Gas  Analyses from Municipal
    Incinerators.  Proc. Nat'l. Incin. Conf., Amer. Soc. Mech. Eng.,
    1964, p. 35.
 TABLE  3-12.    INCINERATOR RESIDUES (Pavoni  et  al.,  1975)
Material
            Washington, D.C.,a
             Metro-Average
          grate-type municipal
              Incinerators
             (% dry weight)
                                                 Rotary-kiln Incinerator
Tin cans
Mill scale and small iron
Iron wire
Massive iron
Nonferrous metals
Stones and bricks
Ceramics
Unburned paper and charcoal
Partially burned organics
Ash
Glass
17.2
6.8
0.7
3.5
1.4
1.3
0.9
8.3
0.7
15.4
44.1
19.3
10.7
0.5
1.9
0.1
.
0.2
3.4
-
57.0
-
+ 6.5 (nonmetallics)






(charcoal )




Sources:
 a Kenahan, C.B., and P.M. Sullivan.   Let's Not Overlook Salvage.  AWPA
   Rep., Vol. 34, No. 3, 1967, p. 5.
   Rampacek, G.  Reclaiming and Recycling Metals and Minerals Found in
   Municipal Incinerator Residues.  Proc., Mineral Waste Utilization Symp.,
   March 27-28, 1968, LIT Research Institute, p. 129.
                                47

-------
          TABLE 3-13.  INCINERATOR WASTEWATER DATA
                       (Pavoni et al., 1975)

Characteristic
pH
Diss. solids, ppm
Susp. solids, ppm




Total solids, % volatile
Hardness (CaC03),
ppm
Sulfate (504), ppm
Phosphate (.Pfy), pDm
Chloride (C), ppm
Alkalinity (CaC03)
5-day BOD @ 20° C
•
, ppm

max.
11.6
9,005
2,680
53.6
1,574
430
55.0
3,650
1,250
--
Plant 1
min.









8.5
597
40
18.5
216
no
0.0
50
2.5
— —
avg.

3







10.4
,116
671
36.3
752
242
23.3
627
516
— —
max.

7
1

1
11.7
,897
,274
51.6
,370
Plant 2
min.

1



780
212.5
2
1

,420
,180
— —



6.0
,341
7
10.5
112
115
1.0
76
292
— *•
avg.
10.5
4,283
372
31.2
889
371
23.5
763
641
— —


Characteristic
PH
Diss. solids, ppm
Susp. solids, ppm






max.
6.5
1,364
398
PI
ant
min.

7

4.8
,818
208
Plant 6
avg.

8

5.8
,838
325
Total solids, % volatile
Hardness (CaC03),
Sulfate (504), ppm
ppm

Phosphate (P04), ppm
Chloride (C), ppm

Alkalinity (CaC03), ppm
5-day BOD @ 20° C

2,780
1,350
15.0
3,821
28
13.5
2
1

3


,440
,125
11.5
,077
16
6.2
2
1

3


,632
,250
13.0
,543
23
8.8
max.

6
2
4.7
,089
,010
24.69
3


2


,780
862
76.2
,404
4
—
min.

5

4.5
,660
848
23.26
3


2


,100
625
32.2
,155
0
—
avg.
4.6
5,822
1,353
23.75
3,437
725
51.5
2,297
1.33
—

Sources:
Plants 1 and 2,
Incinerator
Plants 5 and 6,

USPHS
System
USPHS





Report on the Municipal
of the
District
unpublished
Plant 1 - 110 TPD3Residue Quench
Plant 2 - 125 TPD
Plant 5 - 200 TPD
Plant 6 - 300 TPD
Residue Quench
Cont.
Cont.
data

Sol




id Wastes
of Columbia, 1967.
(SW-llts) (SW-12ts).
(Batch).
(Batch).
Feed-Flyash
Feed-Flyash
Effl
Effl
uent.
uent.
TPD = tons per day
                            43

-------
      Inert sludge from the package plant at the Sun Oil Cordero mine will be
buried in topsoil and graded in the spoil.  Sludge may contain concentrated
levels of trace metals due to the affinity of metals to organics (Council for
Agricultural Science and Technology, 1976).  Possible metals may include:
manganese, iron, aluminum, chromium, arsenic, selenium, antimony, lead, mer-
cury, cadmium, copper, molybdenum, nickel, and zinc (Council for Agricultural
Science and Technology, 1976).

     Ash.produced by incineration at the Wyodak mine will be interlayered with
overburden and buried.  Potential contaminants are shown in Tables 3-12 and
3-13.  Solid wastes will also be buried, and potential pollutants in leachate
are  listed in Table 3-8.

Reclaimed Area Sources
 Fill Materials—

     The  pollution  potential of the fill materials, topsoil, and spoils has
 been discussed  previously  in the subsection "Stockpiles."  The chemistry and
 amount  of pollutants dissolved from the topsoil and spoils during movement of
 water through these materials will depend on the locations of the various sub-
 categories of these materials replaced within the mined area and their rela-
 tion to the modified hydrogeologic system that exists after mining.  The max-
 imum available  quantities  of soluble salts and trace metals can be estimated,
 as  has  been indicated,  but the potential mobility of the trace elements and
 rates of  dissolution of the soluble salts and trace metals from topsoils have
 not been  defined.

     Spoil will  consist of a heterogeneous mixture of overburden material
 originally present  in the  indigenous vadose zone and shallow aquifer systems.
 Overburden consists of  sandstone, shale, and thin or impure coal beds of the
 Wasatch or uppermost Fort  Union Formations.  Scoria, or baked shale and silt-
 stone may also,  be present, together with alluvial material. Partings or coaly
 wastes  above or between coal beds may constitute potential sources of pollu-
 tion at many sites.  Some  parting materials have been found with pH values in
 the acidic range and containing high concentrations of certain constituents.
 As  an example,  analyses of three grab samples of overburden material are
 shown in  Table  3-14, as reported by McTernan (1974).  Samples I and II were
 sandy loam and  Sample III  was a silty clay loam ("Blue-Shale").  Compared to
.Samples I  and II, the silty clay loam had a low pH, 3.9, and higher concen-
 trations  of sulfur, iron,  copper, and magnesium.  The low pH is of signifi-
 cance in  that heavy metals become more soluble in the acidic range.  In con-
 trolled laboratory  experiments, McTernan observed the bacterial oxidation of
 sulfur  with a subsequent increase of pH to about 6.3.  After about 50 days,
 pH  values  once  again decreased.

     Several of the mine environmental impact statements indicate that clay
 partings will be buried in the spoil piles, i.e., below the reclaimed soil
 zone.   Such a procedure will position potential sources of pollution within
 the vadose zone.
                                     49

-------
           TABLE 3-14.   CHEMICAL AND PHYSICAL  DATA:  THREE OVERBURDEN
                        GRAB SAMPLES (McTernan,  1974)

Characteristic
Sulfur (ppm)
Iron (ppm)
Copper (ppm)
Calcium (ppm)
Magnesium (ppm)
NOo (ppm)
PH
Texture

Sample I
70
5.1
0.6
1,900
330
2.0
8.1
Sandy loam

Sample II
630
4.2
0.3
1,500
310
3.0
8.1
Sandy loam

Sample III
(blue-shale)
1,200
46
722
1,400
670
2.0
3.9
Silty clay loam
       In  addition to partings, isolated lenses of precipitated gypsum (e.g.,
  as  selenite) or marcasite (iron sulfide) have been observed.   Tait (1976), for
  example,  noted the presence of both gypsum and marcasite within fractures of
  coal  aquifers on the Coal Creek property of ARCO.   Relatively pure specimens
  of  selenite have been observed on the sides of a landfill  trench,  near the
  City  of  Gillette.

       The vadose zone developed within spoil piles  will  include the following
  potential sources:  (1) sources exposed on fresh surfaces  of  replaced over-
  burden;  (2) sources on layers of compacted partings,  coaly wastes, or toxic
  strata;  and (3) sources within buried solid wastes.

       In  his studies of strip-mine spoils in the Powder  River  Basin, Rahn (1976)
  observed  that samples of water from spoils are significantly  more  concentrated
  in  total  salt than native groundwater.   Particularly  high  concentrations of
  calcium  and sulfate were observed.  He attributed  increased salt content
  to  the dissolution of salts exposed on the spoils  blocks.   Calcium and
  sulfate levels were high because of the presence of gypsum crystals - gypsum
  is the most soluble of exposed salts.   High concentrations of magnesium were
 also observed.   Manganese was high in  most samples examined by Rahn (1976),
 possibly reflecting the weathering of pyrolusite or psilomelane.   Excessive
 levels of sodium were  noted  in some samples.   The  pH  values of spoil  water
 samples were  generally in the alkaline  range.

     Specific  pollutants  related to solid  wastes (including sludge) buried
 within the modified vadose zone  are discussed  elsewhere.   In  summary, leachate
 generated in such wastes  could run the  gamut from  hazardous substances to
 excessive concentrations  of  heavy  metals.

     Environmental impact statements for several of the mine  sites indicate
 that parting material, coaly wastes, or toxic  strata  will  be  buried within the
 spoils.   The major pollutants  in these  layered-in  deposits are heavy metals  -
 although  high concentrations of  calcium sulfate  may also be present   These
 layers may be more compacted than  the overlying  spoil, possibly leading to the
 formation of perched water tables  following  surface flooding.   Anaerobic con-
ditions brought about by the water  table conditions may have  an influence on
 heavy metals movement.

                                     50

-------
     In particular, the following effects may occur:

     •  Reducing conditions may increase the mobility of cationic
        heavy metals.  That is, "...trace contaminants arsenic,
        beryllium, chromium, copper, iron, nickel, selenium,
        vanadium, and zinc are much more mobile under anaerobic
        soil conditions, all other factors the same"  (Fuller,  1977)

     •  Reducing conditions lead to the formation of  hydrogen
        sulfide and consequently heavy metal sulfides.  These
        metals are relatively insoluble.

     Since these two factors are counteractive,  the net movement  of metals may
be hard to predict.  Other conditions should also be  taken  into account.  For
example, partings from several  mine sites have low pH values.   Metals  are more
mobile in the acid range (Fuller, 1977).  However, the pH of partings  may
change before being inundated,  particularly if an organic source  of energy is
available for bacteria capable of oxidizing sulfur (McTernan,  1974).

     The EIS for the Belle Ayr South mine indicates high values of organic
copper, zinc, and selenium in overburden samples.  In addition, certain  sample
profiles disclosed higher EC and SAR values within the upper five feet.  Table
3-14 (McTernan, 1974) includes analyses from three overburden  samples.  Obvi-
ously, Sample III  (blue-shale) contained the highest  concentrations of sulfur,
iron, copper, and magnesium.  The pH for Sample III was 3.9.

     Analyses of saturation extracts from sample holes at the  Eagle  Butte mine
site showed  high values for both chloride and sulfate.  Regarding heavy metals
in overburden, the EIS stated:  "There exists no definable trend of trace
metals within the  overburden... For all overburden samples, cadmium  (Cd) val-
ues range from a minimum 0.03 ppm to a maximum 0.85 ppm and average  0.174 ppm.
Mercury (Hg) ranges from 1.63 ppm to 51.63 ppm... With exception of 16 samples
which possess measured lead concentrations ranging from 1.056  to 2.96 ppm,  all
remaining samples  disclose concentrations less than 1 ppm.   For all  samples,
lead (Pb) concentrations range from 0.003 to 2.96 ppm and average 0.43 ppm."
Since native soils normally contain between 40 and 70 ppm lead (Fuller, 1977),
these values are not excessive.  One .sample of partings contained a  pH of 4.5.

     Drever  et al. (1977) reported that heavy metals  were strongly enriched
near the margins of coal seams at the Black Thunder mine.  Table 3-15, repro-
duced from their report, illustrates relative magnitudes of heavy metals and
sulfur in the overburden core samples.  Note the concentration of metals
between 77 and 79  feet.  Relative to the other core samples, samples  in this
range contained high levels of arsenic, cadmium, calcium, mercury, molybdenum,
lead, uranium, and sulfur.  Table 3-16 compares average trace metal  concen-
trations from cores at the Black Thunder mine with values for average U.S.
coal, average shale, and Okefenokee peat.  The upper interface region contained
higher values of beryllium, calcium, lead, and uranium than other samples.
However, Drever et al. (1977) pointed out that "...the trace element  concen-
trations in the interface region are not outstandingly high in comparison to
average shale or coal."

                                     51

-------
TABLE 3-15.  TRACE ELEMENT CONTENT OF COAL AND ASSOCIATED ROCKS,
             CORE BT249 (coal analyses reported on whole coal
             basis)(Drever et al., 1977)
•*- • — 	 	
Depth
L-ayer (feet)
Overburden
10
13
16
19
22
25
27
32
33
36
39
42
45
48
51
54
57
60
63
65
70
73
76
76
77.3
77.3
78.3
Overburden
78.6
Coal seam
78.6
82
92
100
106
114
120
128
136
146
Coal seam
149
Floor
149
151.5
152
153.5
153.5
154.5
156.5
157
158.3
159.5
As
(ppm)
<0.05
0.13
<0.05
<0.05
<0.05
<0.05
0.08
<0.05
0.08
0.45
0.13
<0.05
0.30
0.60
0.40
0.40
0.55
2.5
-
1.0
0.35
7.5
4.0
0.60
0.50
0.25
0.63

0.78

1.0
0.02
0.02
0.02
0.04
<0.1
0.09
0.07
0.02
0.15

0.20

<0.1
1.1
0.15
0.35
0.54
1.6
0.37
0.09
1.0
-
*— _^ — -~^—
Be
(ppm)
5
4
4
3
4
3
6
6
5
5
3
<2
5
4
5
4
5
5
5
4
3
<2
10
11
7
6
10

20

3.6
0.5
0.48
0.14
0.15
0.2
0.26
0.09
0.28
0.3

1.9

6
5
8
9
4
11
9
11
7
8
• II. 	 mml
Cd
(ppm)
<4
<4
<4
<4
<4
<4
<4
<4
<4
<4
0
0
<4
<4
<4
<4
<4
<4
<4
<4
<4
<4
<4
<4
10
<3
6

<4

2
<0
<0
<0
<0
<0
<0
<0
<0
<0

0

<4
<2
<4
<4
<2
<2
<2
<4
<4
0
.5
.2

















.0
.3
.4
.4
.4
.4
.4
.4
.4
.4

.05










.3
Cu
(ppm)
25
15
13
11
12
15
21
18
21
20
10
8
14
30
25
24
25
27
20
25
15
14
70
63
72
43
120

54

26
7.4
9
12
6
8.3
4
3
5
4.5

83

55
58
33
33
25
48
35
160
75
30
Hg
(ppm)
0.10
0.13
0.03
0.03
0.04
0.04
0.23
0.11
0.18
0.14
0.06
<0.02
0.09
0.10
0.10
0.08
_
0.02
<0.02
0.10
0.15
0.04
0.05
-
1.07
0.02
-

0.66

0.37
0.06
0.06
0.05
0.05
0.06
0.02
0.05
0.04
0.04

0.05

<0.02
0.47
<0.02
0.08
-
2.0
0.48
0.49
0.78
-
Mo
(ppm)
5
<4
<4
6
<4
<4
6
<4
<4
5
5
<4
5
5
6
5
5
8
<4
5
6
7
20
10
23
<20
<20

54

5.3
<2
<2
<2
<2
<1
<1
<2
<2
<1

4.1

<20
9
<20
<20
9
27
20
<20
15
<20
Pb
(ppm)
33
30
20
30
30
30
35
50
35
50
30
20
30
23
28
33
32
31
32
25
40
30
100
73
100
55
145

46

19
5.8
6
7
5
4.3
5
4
5
4.5

21

80
69
80
100
36
47
38
120
60
80
U
(ppm)
2
3
2
-
3
-
4
5
5
-
-
-
5
6
11
6
9

12

3
0.06
0.35
0.26
0.16
0.41
0.15
0.06
0.12
0.10

4

4
5.3

6
2
6
12

—
-
S
-
-
-
-
-
-
-
-
-
-
0.25 '
0.22
0.44
0.03
0.15

1.03

0.89
0.63
0.51
0.48
0.32
0.35
0.26
0.24
0.25
0.52

0.46

0.03
0.44
0.01

-
-
-
-
-
-
Ash
W
92.3
94.8
96.5
95.7
92.3
92.2
92.2
97.5
88.2
-
91.4
93.5
89.9
90.7
89.6
93.4
93.1
96.7
85.0
69.8
45.2
85.3
85.4

39.9

13.2
5.3
5.4
4.2
3.8
4.5
4.4
2.8
3.8
4.5

11.9

83:2
43.1
89.1
90.7
44.5
26.7
31.9
70.0
50.5
92.1
                                 52

-------
co
                   TABLE  3-16.  COMPARISON OF AVERAGE TRACE ELEMENT CONCENTRATIONS  (ppm)
                                (Drever et al., 1977)

Sample
Coal seam
excluding margins
Upper interface
region
Average
U.S. coal
Average shale
Okefenokee peat
Be
0.3
11

1.6
3
-
Cu
6.6
70

15
45
25
Mo
1
21

7.5
2.6
-
Pb
5
87

35
20
13
As
0.05
2.5

14
13
-
Hg
0.05
0.3

0.2
0.4
0.4
U
0.2
8

4.0
3.7
-

-------
      Analyses  of  overburden,  included  in  the  EIS for the Rawhide Mine, clear-
 ly show that partings  between coal  seams  have low  pH values and sometimes
 high concentrations  of heavy  metals.   Table 3-17,  reproduced from the EIS
 from the Rawhide  Mine,  illustrates  that a  low pH value of 4.9 was reported
 for partings in hole NRH-76C  (202-212.4 feet).  Relative to some other
 samples, the concentrations of zinc, iron, and molybdenum were higher in the
 sample from NRH-76C.

      Data on specific  pollutants  at the Kerr-McGee Jacobs Ranch Mine site are
 limited.  There are  no reported seams  in  the  overburden with low pH values.
 High concentrations  of calcium, magnesium, and sulfur were present in a
 reported analysis.

      The EIS for  the Cordero  Mine states  that no significant amounts of toxic
 substances have been found  in either the  topsoil or overburden analyses and
 none is anticipated.  Despite this  statement,  results of analyses of over-
 burden samples in the  Mining  and  Reclamation  Plan  illustrate some samples had
 low pH values. For-example,  the  sample from  19 to 21 feet at location 75-14-2
 had a pH of 4.5 and  higher  than normal levels  of phosphorus, nitrate nitro-
 gen, iron, and cadmium.

^OIL AND GAS EXTRACTION

      Potential groundwater  pollutants  derived from oil and gas extraction in-
 clude oil, from casing leaks, surface  leaks and spills, and seepage from the
 mud pit; nitrates from incomplete explosions  in shot holes; bentonite and
 organics from drilling muds such  as Revert; salts  from'brines and formation
 waters encountered during drilling; and hydrocarbons, which have fallen to the
 ground from atmospheric emissions.

 CONSTRUCTION

      Construction waste is  usually  solid waste, and is disposed of in land-
 fills at the mine or in the Gillette Landfill.  Landfill pollutants are
 discussed under municipal sources.  Some of these  pollutants come from decom-
 posing and/or  disassociating  construction wastes.

      Pollutants introduced by construction include, but are not limited to,
 the following:

           TDS                        Chloride
           Calcium                   Sulfate
           Iron                       COD
           Copper                     BOD
           Zinc                       pH (acid  generation)
           Chromium                   Oil and  grease
          Manganese                  (Other trace  metals)

     The above  list  includes  the  most  common  contaminants introduced  by  dete-
rioration of construction wastes.   An  exact appraisal of the pollutants
generated would require a detailed  listing of discarded material.
                                     54

-------
                  TABLE 3-17.   ANALYSES OF OVERBURDEN MATERIALS (U.S.  Geological  Survey,  1974b)
cn
Hole No.
NRH-45C

NRH-46C

NRH-76C


NRH-76C
NRH-76C



HRH-79C


NRH-79C


NRH-92C

NRH-98C

NRH-99C


NRH-112C

NRH-112C

NRH-126C




Depth of
staple (ft)
•••HM^B^W^^^BMM^^^B^^B
24-34

7-14

111.5-119.5


119.5-121.4
204-212.4



51-59


59-62


31-43

30-40

120-130


45-55

129-137.3

171-178.5




Sample
description
•i^~_«»»^^^^__^^_
Sllty clay
(overburden)
Clay
(overburden)
Sllty clay
loan
(overburden)
Sllty clay
Sllty clay
(parting
between
coal sea*s)
Sllty clay
loan
(overburden)
Sllty clay
low
(overburden)
Sandy clay
(overburden)
Sllty clay
(overburden)
Sllty clay
lOM
(overburden)
Sllty clay
(overburden)
Clay
(overburden)
Sllty clay
loan
(parting
between
coal seam)
£
"2°
8.1

8.2

8.3


8.7
4.9



7.5


7.6


8.1

8.0

8.3


8.5

7.4

6.8




H
~Salt
7.7

7.5

7.8


8.0
4.7



7.4


7.5


7.9

7.8

7.9


7.9

7.1

6.2




CEC
(•eg/
100 g)
25

20

15


15
73



31


33


24

25

19


21

13

11




Salt
(•rims/
1.3

0.7

1.0


0.7
2.4



4.2


4.2


2.4

2.4
"
1.3


0.8

1.7

0.8




Na
(•eg/
100 g)
0.9

0.5

0.5


0.5
1.1



0.6


0.6


0.6

1.2

1.1


1.6

1.2

1.0




Lie*
(X)
6.7

0.3

3.1


3.*
0



2.4


1.7


7.9

5.0

7.7


5.8

0.5

0




Organic
autter
(X)
0.8

0.9

0.6


0.6
5.5



0.8


1.3


0.5

1.6

1.5


2.2

4.6

4.1




Available nutrients (pp»)
*>3
29

1.0

9.0


11
3.0



10


16


4.0

4.0

10


4.0

1.0

1.0




NH4
1.2

0

0.3


0.3
0.8



0.4


1.0


0.1

0.3

0.8


0.4

0.2

0.2




P
2.0

68

1.0


1.0
1.0



1.0


1.0


1.0

1.0

2.0


3.0

1.0

1.0




K
210

150

140


130
270



160


160


160

270

270


340

280

240




Ca
2500

2100

1700


1700
2600



3900


3800


3200

2900

2000


2000

1300

860




Mg
1000

720

410


410
790



1100


1400


630

790

620


660

460

380




S
^^^^BHHHflBV
180

62

160


180
200



200


200


200

200

200


62

200

39




B
0.6

1.3

0.4


0.6
4.8



0.3


0.2


0.3

0.3

0.3


0.2

0.5

0.7




Zn
PM^^HHMMH
1.7

1.7

3.3


3.9
7.8



0.6


3.0


0.9

2.2

2.5


3.8

20

1.6




Fe
•••V^VHUHIIIIII
13

50

16


15
50



18


10


8.8

14

37


40

46

31




gggg^igggg^^^
7.0

0.5

3.2


3.5
7.0



2.1


0.6


2.9

6.3

4.8


11

10

2.0




Cu
^HH^B^V
2.1

6.6

0.7


0.3
8.2



0.4


1.2


0.2

2.2

1.1


0.7

3.2

1.6





-------
COAL CONVERSION

Steam Electric Power Plants

     Analyses are available for atmospheric emissions and fly ash from the ex-
isting power plant.  Potential pollutants from packaged sewage treatment
plants of the type that the power plant will employ are discussed in another
section.

     The major pollutants found in atmospheric emissions are sulfur dioxide
(S02), nitrogen dioxide (N02), and particulates.

     Sulfur dioxide in the flue gas is produced by oxidation of sulfur in the
coal.  Some of the sulfur is recovered as pyrites, and some of the sulfur
dioxide formed is removed from the flue gas after reacting with alkaline fly
ash.  At this time, it is not anticipated that wet scrubbers for sulfur removal
will be required to meet State and Federal air quality standards; however,
provisions have been made for the addition of scrubbers should they become
necessary.  On the basis of an average sulfur content in coal of 0.50 percent
and about 4 percent sulfur removal in the furnace, S02 emissions from the new
unit will be  less than the allowable limit of 1.2 pounds per million Btu of
heat input.   Tests on Unit 5 show greater than 30 percent sulfur removal.

     Nitrogen oxides (NOX) are formed by oxidation of nitrogen in the combus-
tion of air and fuel, a process which is influenced by firing conditions in
the boiler.   NOX emissions from the boiler in the new plant are guaranteed by
the boiler manufacturer not to exceed 0.7 pound of NO  per million Btu of heat
input.

      Table  3-18(a)  shows  expected operating conditions  for  100 percent  load and
 predicted emissions from  both  existing Unit 5 and the new plant.  Table 3-18(b)
 shows  peak  ground  level concentrations of sulfur dioxide, nitrogen  dioxide, and
 particulates  from  the existing plant, while Table 3-18  (c)  shows predicted
 ground  level  concentrations for the new  plant together with  Unit 5.   Table
3-18(d) gives an analysis  of  the projected ash  from  Unit 5  of the existing  power
 plant.

Gasification

     The potential  pollutants  associated with the Hoe Creek in situ coal  gasi-
fication experiment are related to the water quality of the aquifers of the
area, nature  of explosives used in fracturing,  and material  created or  released
during  the gasification burn.  Pollutants associated with hydro!ogic-geologic
exploration,  placement of  experimental wells, and dewatering are related to
aquifer water quality which is described, in Section  6  (Existing  Groundwater
Quality).  Characteristics of  explosives used are unknown at this  time  but
they could create pollutants  associated  with fracturing of  the coal  seam and
dewatering of the fractured zone.  The gasification  process itself is the major
potential pollution source.   Descriptions of possible pollutants follow.

     Containment of potential  pollutants produced as gasification  byproducts
may  be a major problem of  in  situ processing.   Principal pollutants expected

                                      5G

-------
  TABLE 3-18(a).   PREDICTED OPERATING CONDITIONS AND EMISSIONS FROM
                  UNIT 5 AND THE NEW PLANT UNDER 100 PERCENT LOAD
                  (Black Hills  Power and Light Co.,  1973)
Parameters
                                   Unit 5
    New plant
Fuel rate (Ib/h)
Flue gas rate (Ib/h)
Heating value (Btu/h)
Heat input (Btu/h)
Predicted emissions (Ib/h)
  S02
  N02
  Particulates
                                32,000
                               295,400
                                 8,255
                                   266 million

                                   320
                                   288
                                    90
440,000
      4.07 million
  8,255
      3.6 billion

  4,240
  2,526
    281
TABLE 3-18(b)
                 PEAK GROUND LEVEL CONTAMINANTS FROM EXISTING PLANT
                 (Black Hills Power and Light Co., 1973)

Contaminants
so2
3-h avg
24-h avg
Annual avg
N02
Annual avg
Parti culates
24-h avg
Annual avg
Peak
concentration
0.233 ppm
0.055
0.0049
0.0056 ppm
309.1 yg/m3
29.5
Wyomi ng
standard
0.5 ppm
0.1
0.02
0.05 ppm
150 pg/m
60
Federal
primary standard
0
0
0
260
75
.14 ppm
.03
.05 ppm
yg/m
                                  57

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TABLE 3-18(c).  PREDICTED COMBINED GROUND LEVEL POLLUTANT
                CONCENTRATIONS FROM NEW PLANT AND
                EXISTING UNIT 5 (Black Hills Power and Light
   	Co., 1973)	

                          Peak           Federal
                                        0
   Contaminants      concentration     2  standard
so2
3-h avg
24-h avg
Annual avg

0.078 ppm
0.0109
0.0007

0.5 ppm
0.10
0.02
Annual avg
Parti culates
24-h avg
Annual avg
0.0006 ppm
10.61 yg/m3
0.73
0.05 ppm
3
150 yg/m
60

  TABLE  3-18(d).  PROJECTED CONSTITUENTS OF ASH FROM THE
                 NEW PLANT AND EXISTING UNIT 5(Black Hills
                 Power and Light Co., 1973)

  Compound                                      Percent
Phosphorus pentoxide
Silica
Ferric oxide
Alumina
Titania
Lime
Magnesia
Sulfur tri oxide
Potassium oxide
Sodium oxide
Undetermined
0.9
39.5
6.3
22.6
1.4
21.4
5.3
0.7
0.5
0.7
0.7
                            58

-------
are  hydrogen  sulfide,  ammonia,  hydrogen  cyanide,  phenols,  benzenes, and oils.
High levels of  dissolved  salts  (including  chlorides  and  fluorides) may also
be released from the coal  reaction.   Results of analysis of byproduct water
from synthane gasification (a surface process) are shown in Table 3-19.  These
data may  be representative of in  situ byproducts.

      The  indicated  high levels  of organic  matter  in  byproduct water may con-
tain a  variety  of compounds:

        Tar (phenols,  cresols,  pyridines,  anilines,  catechols)
        Intermediate, and  high boiling point aromatics  (e.g., naphthalenes)
        Saturates
        Olefins
        Thiophenes
        Light oil and/or  naphtha,  BTX (benzene-toluene-xylene),
        naphthalene, thiophene, condensed  light hydrocarbons, and
        disulfide carbon.

      Organic  compounds tentatively identified in  pilot plant studies are
phenol, £ and m cresol, dimethyl phenol (2,4; 2,5; 2,6; 3,4), a naphthol,
and  1,2 dihydronaphthalene.  Results  of  benzene-soluble tars produced as gasi-
fication  byproducts are shown in  Table 3-20.  Coke oven tars are known to con-
tain relatively high levels of  carcinogenic organic  compounds.  Considering
that coke ovens  operate  in the same  temperature  range as some gasification
processes (although at lower pressures than surface  gasifiers), similar prod-
ucts may  be formed  during  coal  gasification.

      The  trace  compounds which  may be formed during coal  gasification have
been  extensively  evaluated.  Many of  the compounds potentially formed are
organometallic  compounds,  such  as:

             metal-porphyrins
             metal-carbonyIs
             metallocenes
             arene carbonyIs
             metal alkyls
             organohydrides
             metal chelates.

The  biological origin  of coal makes it likely that porphyrin compounds are
present.  Porphyrins are known  to bind metals such as vanadium and nickel.
High  partial pressures of  carbon monoxide may lead to metal-carbonyl  formation
(e.g., carbonyls  of nickel, iron and  cobalt).  These toxic compounds are un-
stable at high  temperatures but trace amounts may be produced.  Metallocenes
of iron, nickel,  chromium, vanadium,  tantalum, molybdenum,  and tungsten may
be formed.  Carbon monoxide pressure  may also enhance formation of arene car-
bonyls which are more  stable than metal!ocenes and hence may be common species.
Although metal alloys  are  generally unstable, they may be important in the
mobility of trace metals in the gasification zone.  Stable organohydrides of
lead, tin, germanium and silica may be formed in the reducing gasification en-
vironment.  Metal chelates formed from phenolics, carboxylic acids and ami no
groups may be important to the  mobilization and release of metals.

                                    59

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CT>
O
       TABLE  3-19.   BYPRODUCT WATER ANALYSIS  FROM SYNTHANE GASIFICATION OF VARIOUS COALS (Jones  et  al.,1977)
Water
constituent0
pH
Suspended solids
Phenols
COD
Thiocyanate
Cyanide
Ammonia
Chloride
Carbonate
Bicarbonate
Total sulfur (S04)
Coke
plant
9
50
2,000
7,000
1,000
100
5,000
--
—
—
— —
Illinois
no. 6 coal
8.6
600
2,600
15,000
152
0.6
8,100a
500
6,000b
ll,000b
1,400
Wyoming sub-
bituminous coal
8.7
140
6,000
43,000
23
0.23
9,520
--
—
—
— —
Illinois
char
7.9
24
200
1,700
21
0.1
2,500
31
	
--
—
North Dakota
lignite
9.2
64
6,600
38,000
22
0.1
7,200
—
__
—
--
Western
Kentucky coal
8.9
55
3,700
19,000
200
0.5
10,000
	
_ ...
—
--
Pittsburgh
seam coal
9.3
23
1,700
19,000
188
0.6
11,000
__
— —
-_
„
      a   85 percent free NH3


      b   Not from same analysis

      c
         Units ppm except for pH

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    TABLE 3-20.  MASS SPECTROMETRIC ANALYSIS OF BENZENE-SOLUBLE TARS
                 (units are percent by volume)  (Jones et al. 1977)

Illinois
Structural type No. 6 coala
Benzenes
Indenes
Indains
Naphthalenes
Fluorenes
Acenaphthenes
3- ring aroma tics
Phenyl naphthalenes
4-ring peri condensed
4-ring catacondensed
Phenols
Naphthols
Indanols
Acenaphthenols
Phenatheols
Dibenzofurans
Benzongohthothi ophenes
- B-heterocyclics
Average molecular weight
2.1
8.6b
1.9
11.6
9.6
13.5
13.8
9.8
7.2
4.0
2.8
ob
0.9
—
2.7
6.3
1.7
10.8
212
Montana sub-
Lignite bituminous coal
4.1
1.5
3.5
19.0
7.2
12.0
10.5
3.5
3.5
1.4
13.7
9.7
1.7
2.5
—
5.2
--
3.8
173
3.9
2.6
4.9
15.3
9.7
11.1
9.0
6.4
4.9
3.0
5.5
9.6
1.5
4.6
0.9
5.6
—
5.3
230
Pittsburgh
coal
1.0
6.lb
2.1
16.5
10.7
15.8
14.8
7.6
7.6
4.1
3.0
ob
0.7
2.0
—
4.7
--
8.8
202
a Spectra indicates traces of 5-ring aromatics
b Includes any naphthol present (not resolved in these spectra)
c Data on N-free basis since isotope corrections were estimated
                                   61

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     Because of the aromatic characteristics of coal, polycyclic aromatic
hydrocarbons (PAH) are found in coal conversion products.  Some of these com-
pounds are known to be carcinogenic in experimental animals and in humans.

     Trace metals in coal may also be mobilized during gasification and thus
are potential pollutants.  Analyses by Attari (1973) of pilot plant opera-
tions indicated substantial losses of mercury, selenium, arsenic, tellurium,
lead, and cadmium from solid residues.  Other metals, such as antimony, vana-
dium, nickel, and beryllium, remained in the solid phase.  The characteris-
tics and transport of the metals mobilized during gasification and the
mobility of  those remaining in the solid phase are largely unknown.  According
to Jones et  al. (1977),  trace elements of primary concern in coal gasifi-
cation are:
              antimony
              arsenic
              barium
              beryllium
              boron
              cadmi urn
              chlorine
chromium
copper
fluorine
lead
mercury
molybdenum
nickel
selenium
sulfur
tellurium
uranium
vanadium
zinc.
 MUNICIPAL
 City of Gillette

 Sewage Treatment Plant-

      Sources at the Gillette Wastewater Treatment Plant include leakage from
 aeration,  secondary clarifier and aerobic digester tanks, seepage from the
 sludge holding pond, and seepage from the oxidation pond.  Sources related to
 the  sludge holding pond are described elsewhere.

      Leakage from the tanks may have about the same quality as incoming
 sewage,  although the quality of basal sludge may be superimposed.  No data
 are  available on the quality of wastewater in the Gillette wastewater treat-
 ment plant.  A first estimate based on information from Metcalf and Eddy
 (1975)  on  the typical composition of medium strength domestic sewage is in-
 cluded  in  Table 3-21.

      Also  included in Table 3-21 are possible values of chemical constituents
 in the  "carrier" water.  These values were given by Nelson et al. (1976) for
 the  City of Gillette water supply.  It is assumed that no changes in concen-
 tration occur during domestic uses.  Also, possible effects of infiltration
 from the Donkey Creek line are neglected.  The high COD, TOD, and BOD values
 indicate that organics constitute a potential contaminant in the shallow
 groundwater system.  Similarly, total nitrogen is high.

     Since the groundwater flow system is anaerobic, however, nitrate values
should remain low.   Another chemical constituent in the carrier water which
is beyond recommended limits is sulfate.
                                     62

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TABLE 3-21.  HYPOTHETICAL QUALITY OF WASTEWATER, GILLETTE
             TREATMENT PLANT (Nelson et al.,1976)
      Constituent                  Concentration (ppm)

      Suspended solids - total             200
                       - fixed              50
                       - volatile          150

      BOD  (5-day)                          200

      TOC                                  200

      COD                                  500

      Nitrogen - total as  N                 40
               - organic                    15
               - free  ammonia               25
               - nitrites                     0
               - nitrates                     0

      Phosphorus -  total as  P               10
                 -  organic                   3
                 -  inorganic                 7

      Alkalinity -  as  CaC03                10°
                                           100
      Grease
                                              9.5
      Potassium

      r i  •                                305
      Calcium

                                           158
      Magnesium

                                           220
      Sodium
                                           920
      Sulfate
                                             36
      Chloride
                                           660
      Bicarbonate

      TDS
                             63

-------
      Sludge settled  in  the  base of aeration, clarifier, and digester tanks
 may also contribute  heavy metals to groundwater.  Other constituents entering
 groundwater from the tanks  include fecal bacteria and virus.  Also present
 are amoeboid cysts,  intestinal worm eggs, and parasitic fungi.

      The "oxidation" pond appears to be an overloaded facultative system with
 operating characteristics of an anaerobic lagoon.  Consequently, wastewater
 undergoes some anaerobic digestion.  The quality of water in the pond may be
 a blend of incoming  and outgoing wastewaters.

      Wastewaters entering the  "oxidation" pond from the aerobic digesters
 will reflect the quality of treatment  in the activated sludge process.  Such
 treatment is minimal in the Gillette Treatment Plant.  Therefore, as a first
 approximation, the values for  medium concentration sewage given in Table 3-21
 are assumed also to  be  representative  of wastewater entering the lagoon.

      According to the Missouri Basin Engineering Health Council (1971),
 treatment effectiveness of  a pond in Saskatchewan was as follows:  suspended
 solids, 70 percent;  BOD, 55 percent; COD, 60 percent; and grease, 75 percent.
 If Gillette's pond shows similar efficiencies and the corresponding values
 are used along with  those values shown in Table 3-21, resultant effluent
 concentrations would be BOD, 90 ppm; COD, 200 ppm; and grease, 25 ppm.  The
 high BOD and COD values reflect organics which should be considered a pollu-
 tant present in the  pond.   Chemical constituents increase in concentration
 because of evaporation.  However, changes in sulfate concentrations will occur
 because of the formation of H2S.  Also, because of anaerobic condition, nitro-
 gen constituents will remain about the same.

      Digestion in anaerobic ponds leads to the formation of organic acids,
 lowering the pH.   Similarly, the reducing conditions in anaerobic ponds also
 increase heavy metal  mobility  (Fuller, 1977).  Lund et al. (1976) observed
 heavy metals in soil  solution  extracts 3 meters below the base of effluent
 ponds constructed in coarse-textured soils.  Metal concentrations were lower
 than corresponding values found in extracts beneath sludge ponds, because
 sludges  tend to accumulate  heavy metals.  Nevertheless, the possibility of
 contamination of groundwater beneath the lagoon at Gillette by heavy metals
 should  be considered a  real possibility.  Analyses (courtesy of Ms. Paddock,
 Supervisor,  water and wastewater plants, City of Gillette) of heavy metals
 in  "treatment plant  water"  suggest that high zinc levels might be present in
 lagoon water (see section on "Sludges").

      The  lagoon  at the  Gillette Treatment Plant might contribute bacteria,
 viruses,  and  other pathogenic organisms to the shallow groundwater system.

      It appears  that the septic tank septage (material remaining in the tank
and not discharged to leach fields) is disposed of mainly at the City of
Gillette  landfill.  However, it is entirely possible that septage is occa-
sionally discharged  into the sewer system.  In this case, shock concentra-
tions may reach the treatment plant.  Table 3-22 shows septage characteristics
reported by Silberman (1977).

     In addition  to the constituents found in normal sewage  (and septage),  the

                                     64

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TABLE 3-22.
SEPTIC TANK SEPTAGE CHARACTERISTICS AS REPORTED
IN THE LITERATURE (all  units in ppm, except pH)
(Silberman, 1977)
Septage characteristics3
Total solids
Total fixed solids
Total volatile solids
Total suspended solids
Fixed suspended solids
Volatile suspended solids
Biochemical oxygen demand
Chemical oxygen demand
Ammonia nitrogen
Nitrite nitrogen
Nitrate nitrogen
Organic nitrogen
Total phosphorus
Orthophosphate
Chromium
Alkalinity
Iron
Manganese
Zinc
Cadmi urn
Nickel
Mercury
Hexane extractabl es
Copper
PH
Aluminum
TOC
Grease
Lead
Minimum
6,380
1,880
4,500
5,200
1,600
3,600
3,780
24,700
40
0.2
0.87
26
20
10
1
1,020
163
5.0
50
0.2
1.0
0.022
9,561
8.5
4.2
50
15,000
9,600
2
Maximum
130,000
59,100
71,400
93,400
9,000
30,100
12,400
62,500
150
1.3
9.0
26
310
170
1
1,020
200
5.4
62
0.2
1.0
0.1
9,561
8.5
9
-
-
-
-

 aMinimum and maximum values are presented to show that
  septage characteristics vary substantially.
                              65

-------
 Gillette  Treatment Plant receives industrial wastes of an unknown nature.
 These  should  be considered as potential pollutants.  Table 3-22 lists hazard-
 ous  wastes which are possibly discharged into the Gillette sewer system.

      Sewage  sludge-According to Todd et al.  (1976), the ranking of pollu-
 tants  associated with  sewage sludge  is:

              Physical  - Minor
              Inorganic chemical  - Primary
              Trace elements -   Primary
              Organic chemical -  Primary
              Bacteriological -   Primary
              Radiological  - Minor.

      Sludge  from  the activated  sludge process normally contains up  to 99
 pounds of water per pound  of sludge  solids (U.S. Environmental  Protection
 Agency, 1974).  Consequently digestion occurs under anaerobic conditions.
 The solid matter  in sludge may  consist of 70 percent organic and 30 percent
 inorganic substances  (Health Education Service, nd).  However,  Sommers  et al.
 (1976) reported 50 percent organic matter in sludge collected from  eight
 Indiana cities.

      A breakdown  of the composition  of raw and anaerobically digested sludge,
 reproduced from a report by Wyatt and White  (1975), is given in Table 3-23.
 The high alkalinity and organic acid levels should  be noted.  Sommers et al.
 (1976) found that the  predominant form of N  in sludges was organic  -N,  and
 that NH,-N constituted greater  than  90 percent of the total inorganic N in
 sludges examined  from  eight  Indiana  cities.  Ammonia concentration  in wet
 sludges fell  within the range 200 to 500 ppm in the same  study.  With drying
 of the sludge,  therefore, one would expect production of considerable N03-N.
 This could be a source at  the Gillette sludge disposal pond.

      Organic  matter in sludge has an affinity for the heavy metals  in waste-
 water  (Council  for Agricultural  Science and Technology, 1976).  For example,
 Mitchell  (1964) reported that copper, cobalt and chromium  chelates were  found
 in the fulvic acid fraction of  organic matter.  Concentrations  of heavy metals
 vary widely  from city  to city,  depending for example on degree  of industriali-
 zation, storm water volumes, etc.  Table 3-24 presents metals found in  sludges
 (Dean  and Smith, 1973).  All metals  are present in  excessive concentrations;
 however,  levels of lead, copper,  and zinc are particularly high.  Regarding
 mobility of  heavy metals in  sludge,  studies  by Lund et  al.  (1976)  demon-
 strated that heavy metals  migrated to depths as great as  3 meters  below
 anaerobically digested sludge holding ponds.  The metals  examined were  Zn, Cd,
 Cu,  Cr, and Ni.  The soils were  coarse-textured.  The authors found that re-
 distribution  of metals  was closely related to changes in  COD of soil samples
 with depth.   Metal movement was  thus attributed to  the formation of organic
 chelates.  Other possible  factors promoting metal migration include pH  and oxi-
 dation  reduction potential.  For example, during the first stage of anaerobic
 digestion of  sludge, organic acid formation lowers  the pH to a  value of about
 5.1  (Health Education  Service,  nd).  The lower pH  promotes  the flux of
 catiomc heavy metals  (Fuller,  1977).  Also, reducing conditions in soil  pro-
motes the movement of As, Be, Cr, Cu, Cn, Fe, and Zn, but has little effect  on


                                     66

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         TABLE 3-23.  TYPICAL CHEMICAL COMPOSITION  OF  RAW AND
                      ANAEROBICALLY DIGESTED SLUDGE (Hyatt  and
                      White, 1975)

Item
Total dry solids (TS), %
Volatile solids (% of TS)
Grease and fats (ether
soluble, % of TS)
Protein (% of TS)
Nitrogen (N, % of TS)
Phosphorus (P205, % of TS)
Potash (K20, % of TS)
Cellulose (% of TS)
Iron (not as sulfide)
Silica (Si02, % of TS)
PH
Alkalinity (ppm as
CaC03)
Organic acids (ppm
as HAc)
Thermal content (Btu/lb)
Raw primary
Range
2.0-7.0
60-80

6.0-30.0
20-30
1.5-4.0
0.8-2.8
0-1.0
8.0-15.0
2.0-4.0
15.0-20.0
5.0-8.0

500-1,500

200-2,000
6,800-10,000
sludge
Typical
4.0
65

( )
25
2.5
1.6
0.4
10.0
2.5
( )a
6.0

600

500
7,600b
Digested sludge
Range
6.0-12.0
30-60

5.0-20.0
15-20
1.6-6.0
1.5-4.0
0.0-3.0
8.0-15.0
3.0-8.0
10.0-20.0
6.5-7.5

2,500-3,500

100-600
2,700-6,800
Typical
10.0
40.0

( )a
18
3.0
2.5
1.0
10.0
4.0
( )a
7.0

3,000

200
4,000C
aData not shown in reference cited
K
 Based on 65 percent volatile matter

cBased on 40 percent volatile matter
                                  67

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 the movement of Cd,  Pb,  and  Hg  (Fuller,  1977).


                    TABLE  3-24.   METALS IN SLUDGE,  1971-1973
                                 (Dean and Smith,  1973)

Li terature
Element
Cd
Cu
Hg
Ni
Pb
Zn
Geometri c
mean
(ppm)
61
906
14.5
223
404
2420
Spread9
5.89
2.66
5.24
4.54
4.13
2.78
Atomic absorption
geometric
mean
(ppm)
93
1840
3.2
733
2400
6380

              aSpread  is  antilog  of standard deviation of log-
               normal  distribution.
      Anaerobic conditions  obviously occur in both the sludge lagoon and "oxi-
 dation" pond at the Gillette wastewater treatment plant.  Because of the shal-
 low water table at the  site, heavy metals may be introduced almost directly
 into the aquifier.   A mitigating factor, however, is that the benthic deposits
 may have clogged the bottoms of both the sludge pond and "oxidation" pond.

      Twenty samples of  water at the Gillette wastewater treatment plant were
 analyzed in July 1976 for  the  following heavy metals:  Pb, Zn, Cd, Cr, and Hg.
 According to the results  (courtesy MS. Paddock), values of Cd, Cr, and Hg were
 consistently below detection limits.  One sample showed a lead concentration
 of 0.5 ppm and the remaining 19 were less than 0.1 ppm in lead.   In contrast
 to these metals, the concentrations of Zn averaged 0.289 ppm.  Undoubtedly,
 all  metals are more highly concentrated in Gillette plant sludge, and the con-
 centration of zinc may  be  excessively high.

      In addition to chemical pollutants, sludge contains high concentrations
 of fecal  coliform bacteria and viruses, and lesser quantities of  intestinal
 and  respiratory organisms  (Dean and Smith, 1973).  Also amoeboid  cysts, in-
 testinal  worm eggs  and  parasitic fungi may be present (Dean and Smith, 1973).
 Such  organisms  remain viable in sludge.

      Sewerline  1eakage —Sewer  leaks allow raw sewage to enter the subsurface
environment.  The  sewage comes from households and businesses in  the  community
and,  in the  case  of  Gillette,  industry as well.  Seasonal variation of sewage
composition  can  occur due  to varying proportions of domestic  and  industrial
waste.  Gillette wastes have a higher domestic fraction during the  summer


                                     68

-------
 because  summer  populations  are  higher  than winter  populations.   Industry
 levels are  relatively  stable year  round.

      Dissolved  minerals  in  Gillette  sewage include all major constituents
 (Ca,  Na,  K,  Mg,  HCC>3,  $04,  Cl)  and several trace constituents  (principally
 Fe, Cu,  Mn).  Diluted  organics  include nitrogen forms such as  ammonium,
 nitrate,  urea,  and  proteins.  Settleable  solids include grit,  sand, soaps,
 greases,  tars,  animal  fats, hair,  oil,  and other organic matter.  All of
 these species can be thought of as potential  pollutants, although the mobil-
 ity of the  various  substances will vary considerably.

 Septic Tanks-

   The characteristics of septic tanks  as potential pollution  sources were
 presented earlier under  the discussion of mine sanitary wastes.

 Landfills or Dumps-

      The Gillette landfill  site encompasses  the following sources:

              Metal  disposal area
              Oil waste disposal  site
              Dead animal  pit
              Garbage trenches
              Oily wastes  and septic  tank  pumpage sites
              Tire disposal  site
              Covered dump.

      Metal  disposal area-This area is  used  for disposal  of  metal  objects,
 such  as  refrigerators, old  cars, and barrels.  Also tires, batteries, and
 wooden items  are included.  Potential  pollutants associated with metal items
 (e.g., in alloys) could  include any  or  all heavy metals, such as manganese,
 iron, aluminum,  chromium, antimony,  lead, copper,  cadmium, nickel, and zinc.
 Since hazardous  wastes of all types  are permitted  at the waste disposal
 site, the metal  drums  could contain  residues  ranging from oil to pesticides.

      Oily waste  disposal  area-Waste  oils  in  the  disposal  pit may include
 crankcase oil,  transmission fluid, gear lubricants, hydraulic oils, and
 possibly  kerosene and  other solvents.   Representative assays of crankcase
 drain oils  indicate the presence of  the following:  carbon, nitrogen, sulfur,
 lead, zinc,  barium, calcium, phosphorus,  and  iron.  Additives included with
 the original lubricating  oil, such as detergents and pour-depressants, may
 be present  in crankcase oil.  The  organic fraction of additives may be dissi-
 pated by  combustion or reactions with  the oil, but inorganics concentrate.
 According to Weinstein (1974),  drain oils contain  significant amounts of
 unchanged polyisobutylene and polymethacrylate additives.  The percent by
 weight of nitrogen in  crankcase drain oils may range from 0.13 to 0.21
 (Weinstein, 1974).

     The  solution resulting  from flushing service station gasoline tanks may
be dumped into the  oil  waste pit.  Such waste could include high organic and
lead  concentrations.  Because  of the  lack of restrictions at the landfill, it


                                     69

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 is  possible  that  hazardous wastes could be disposed of in the oil waste pit.
 Table  3-22 lists  possible hazardous wastes.

     Open burning is permitted near the oil waste disposal site.  Pesticide
 containers and  other wastes are accepted.  Burning of these items could create
 fly ash  with high concentrations of organics and possibly heavy metals.

     Dead animal  pit-The dead animal pit is a source of high BOD, COD, and
 TOC, as  well  as lesser amounts of chemical constituents.  The high TOC sug-
 gests  that organics could migrate from the pit.  Pathogenic organisms and
 virus  are possibly present in abundance.  Substances used in the euthanasia of
 the animals  will  also be present in unknown concentrations.

     Garbage disposal site-Garbage is disposed of in two active trenches,
 each about 30 to  40 feet wide, 400 to 500 feet long, and 20 to 30 feet deep.
 A third  trench  of the same dimensions is used to provide backfill for the
 above  trenches.   Surface drainage runs into the pits.

     The range  in quality observed in municipal landfill leachate is shown in
 Table  3-8, reproduced from a paper by Pohland and Engelbrecht (1976).  These
 authors  point out that leachate is most objectionable from a pollution view-
 point  when containing high concentrations of organic matter, high TDS, and low
 pH.  As  shown on  Table 3-8, the following constituents are potential contami-
 nants:   organics,  nitrate, calcium, chloride, sodium, potassium, sulfate, man-
 ganese,  magnesium, iron, zinc, copper, cadmium, and lead.  Decreasing pH
 increases the solubility of heavy metals present in the waste.  Similarly,
 anaerobic conditions at the soil-landfill interface will promote the mobility
 of  heavy metals indigenous to the soil.  The population of microorganisms in
 leachate may be limited by the initially elevated temperatures together with
 other  inactivating properties (Pohland and Engelbrecht, 1976).  In other words,
 pathogenic organisms might not be of concern as polluting sources in leachate.

     The problem  of leachate production and associated potential contaminants
 is  aggravated at  the Gillette disposal site by surface runoff into the
 trenches.  Not only does such runoff promote leachate formation, but also con-
 taminants are introduced with the runoff water.  For example, the overburden
 layers immediately above the coal seam exposed by the trench were observed to
 contain  free  sulfur and gypsum.  A water sample of runoff was collected from a
 pool at  the  base  of the third trench in June 1977, the day after a thunder-
 storm  in the  area.  Table 3-25 shows the results of an analysis of the sample.
 The sample was not preserved (except by freezing); consequently, results for
 pH, C03, HC03,  NH4> and N03 are questionable.  An equivalents  per million
 (epm)  balance shows that the ratio of cations  to anions  is  1.23.  Sulfate
 values are questionable because of the method  used  (Hach  Kit)  and errors  are
 introduced by dilution to bring results within the  range  of the  instrument.
 However, the  values illustrate that probably high concentrations of chloride,
 sulfate, sodium,  and calcium are introduced into solid waste during runoff.
 If the pH is  as low as the value shown, runoff water may  also contain heavy
metals and promote the mobility of heavy metals in  leachate.
                                      70

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          TABLE 3-25.  ANALYSIS OF RUNOFF SAMPLE IN THIRD TRENCH AT
                       THE CITY OF GILLETTE LANDFILL IN JUNE 1977
                        (ppm except for  pH)
                  Water constituent        Water constituent
PH
EC
C>
co3
HC03
so4
4.95
32.0
545
0
78.1
1,500
Na
K
Ca
Mg
NH4
N03
338
18
499
226
6.16
2.80
     Oil waste and septic^ tajikjjumpage pits—Two pits at the Gillette disposal
site are used to dispose of oil wastes and septic tank pumpage.  Observation
of the types of wastes disposed of in these pits suggests that hazardous
wastes are also included.

     The type of oily wastes and associated contaminants are probably the same
as those disposed of in the oil waste disposal pit, and hazardous wastes are
probably among those given in Table 3-22.

     No information is available on the quality of the septage disposed of in
the septic tank pumpage pit.  The characteristics of septage are known to vary
considerably, particularly in communities  which  do not regulate the collec-
tion and disposal of septage (U.S. Environmental  Protection Agency, 1974).
"In these cases, septage haulers will indiscriminately include septic tank
contents along with raw wastewater collected from pit toilets, wastes from
camping trailer pump-out stations, waste motor oil from service stations, cut-
ting oil and other hard-to-treat or toxic wastes from small industries through-
out the communities" (U.S. Environmental Protection Agency, 1974).

     Table 3-22 indicates the possible large range in septage characteristics.
The high TOC and COD values illustrate that organics are a possible contami-
nant.  Other constituents of concern are:  nitrogen, chromium, iron, manga-
nese, zinc, cadmium, nickel, copper, and aluminum.  Septage may also contain
high concentrations of parasite microorganisms and viruses.

     Tire disposal site-Up the hill from the oily waste and septage disposal
pits is an area for disposal of tires.  Oil wastes are also evident in this
pit, with associated potential contaminants.  Tires are basically nonbiode-
gradable.  Fecal matter from rodents may constitute a pollution source as do
the remains of dead rodents.  Tires are also a potential fire hazard.  Con-
stituents in fly ash from burning tires may be potential sources of contamina-
tion.   Possibly included are organics and heavy metals.


                                     71

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      Covered dump-No information is available on the area! extent and composi-
 tion  of  solid wastes in the covered dump at the landfill site.  Using present
 practices as a guide, it is possible that any or all of the contaminants dis-
 cussed above are present.

 Water Treatment Facility-

   .  The two potential pollutants related to the City of Gillette water treat-
 ment  plant are precipitated solids from the lime softening process and con-
 centrated wastewater.  Precipitated solids comprise CaC03 and are disposed of
 in  the landfill.

      A sample of treatment plant wastewater was obtained from Stone Pile Creek,
 directly behind the plant, in June 1977.  The sample was not preserved (except
 by  freezing).  The resultant analysis of major constituents and other charac-
 teristics of the water sample are shown in Table 3-26.  The ratio of cations
 to  anions is 0.84, indicating errors in analyses, principally sulfate, or the
 presence of undetermined constituents.  On the basis of this analysis, however,
 it  appears that sulfate is the principal contaminant.


           TABLE 3-26.  JUNE 1977 ANALYSIS OF WATER FROM STONE PILE
                        CREEK BEHIND GILLETTE WATER TREATMENT PLANT
                        (pptn except for pH)
                  Water constituent        Water constituent
PH
EC
Cl
co3
HC03
8.5
1.70
14
3.0
109.8
so4
Na
K
Ca
Mg
1,350
55
11
134
165

Urban Runoff-

     Sartor and Boyd (1977) reported on studies to determine the nature and
concentrations of contaminants in urban runoff.  Results were based on samples
collected for a number of studies throughout the U.S.  Among the more signifi-
cant conclusions with respect to pollutants were the following:

            •  Runoff from street surfaces is generally highly contaminated.
               In fact, it is similar in many respects to sanitary sewage.

            •  The major constituents of street surface contaminants were con-
               sistently found to be inorganic, mineral-like matter, similar
               to common sand and silt.


                                      72

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             •  The quantity of contaminant material  existing at  a given test
                site was  found to depend upon the  length of time  which had
                elapsed  since the site was last cleaned, intentionally (by
                sweeping  or flushing)  or by rainfall.

             •  The quantity of contaminated material  existing on street sur-
                faces was found to vary widely depending upon a range of
                factors.

     Quantity and characteristics of  contaminants  observed in urban runoff in
the studies by Sartor and Boyd (1977) are shown in Table 3-27.   Note particu-
larly  the  high concentrations of total  solids, coliforms, zinc,  copper, lead,
and chromium.

     Urban runoff for Gillette will also contain  high concentrations of ordi-
nary salt  used for clearing roads.

Other  Municipalities

     The only identified potential pollution sources  at outlying municipalities
are sewage treatment plants.  The sewage effluents at these point sources will
be similar to wastes generated at the City of Gillette treatment plant, and
the reader is referenced to that section of the report.  Total dissolved solids
may be lower at outlying municipalities, due to the  lower TDS of the water
supply itself.  However, the actual makeup of the  sewage effluents depends
on the design and operation of the particular package plant.


         TABLE 3-27.  QUANTITY AND CHARACTERISTICS OF CONTAMINANTS
                       IN URBAN RUNOFF (Sartor and  Boyd, 1977)
                                                    Weight means
                                                  for all samples
                       Measured constituents	(Ib/curfa mile)

                       Total solids                     1400
                       Oxygen demand
                          BODc '                         13.5
                          COD                          95
                          Volatile solids                 100
                       Algal nutrients
                          Phosphates                      1.1
                          Nitrates                       0.094
                          Kjeldahl nitrogen                 2.2
                       Bacteriological                         Q
                          Total coliforms (org/curb mile)      99 * 10*
                          Fecal coliforms (org/curb mile)     5.6 * 10
                       Heavy metals
                          Zinc                          0.65
                          Copper                         0.20
                          Lead                          0.57
                          Nickel                         0.05
                          Mercury                        0.073
                          Chromium                       0.11
                       Pesticides                              ,
                          p.p-DDD                      67 x 10'°
                          p.p-DDT                      61 - 10'°
                          Dieldrin                     24 * 10'°
                          Polychlorinated biphenyls         1100 * 10~°
                                         73

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                                  SECTION 4

                               GROUNDWATER USAGE


      Campbell  County  receives  an average of only 15 inches of precipitation per
 year, much of  which is  in  the  form of snow.  Most of the streams are ephemeral,
 but even.permanent rivers,  such as the Belle Fourche, are used only for stock
 watering and a small  amount of irrigation.  The primary water supply for all
 uses is groundwater.

      Groundwater usage  can be  divided into four broad categories:  municipal,
 industrial, agricultural,  and  rural domestic.  The only major municipality
 within the project area is the City of Gillette.  The core city is supplied with
 water through  a City  distribution system, while trailer courts and subdivisions
 on the periphery have each developed its own water system.  The town of Wright,
 located at Reno Junction,  also has its own water supply system.  Major
 industries which use  groundwater include coal strip mining, electric power gen-
 eration, experimental gasification, and secondary oil recovery.  Agricultural
 water uses include stock watering and some irrigation.

 MUNICIPAL USAGE

 City of Gillette

      The primary location  of municipal water usage is the City of Gillette.  Now
 supporting a  population of 13,000, most of the City itself is supplied through
 a  central  distribution  system.  Pump station logs and City meter records show
 that in 1976 average  daily usage was approximately 105 gallons per capita and
 that the maximum daily  usage was about 240 gallons per capita  (Nelson, et al.
 1976).   Roughly 3 million  gallons of water per day flow through the water treat-
 ment plant,  of which  approximately 1.7 mgd enter the sewage treatment plant
 (Jeff Smith, City Engineer, personal communication, 1977).

      The City  water comes  from a mixture of hard and soft water wells.  There
 are  currently  20  operational hard water wells, all except 2 of which are locat-
 ed in a  single well field  northwest of the City and north of the railroad,  in
 Sections 21 and  22,  T50N,  R72W.   The wells range from 182 to 355 feet in depth
 and  draw water from the  Wasatch Formation.  When they were drilled in 1969,
water levels ranged from 60 to 80 feet below ground surface, and individual well
yields were generally from 50 to 100 gpm (Anderson and Kelly, 1977).  In 1976,
the hard water wells  were found to be producing at 75 percent of their original
capacity  (Nelson  et al., 1976), and in September 1977, water levels were found
to range between  78 and  94  feet below ground surface.
                                      74

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     The hard water well system is clearly inadequate to meet the needs of
Gillette's growing population.  Not only is the water table as a whole declin-
ing, but the cones of depression from neighboring wells are interfering with
one another (Nelson et al., 1976).  The wells are in poor repair, with broken
flow meters and pressure gages and valves that have rusted shut.  There is no
monitoring of the well system at this time.

     In 1976, a consulting firm (Nelson et al., 1976) was hired by the City of
Gillette to study the water supply situation.  At  their  urging, the City expand-
ed its soft water well system during 1977.  The City currently has 12 soft
water wells, 7 of which have been drilled into the Fort Union Formation during
the past year.  The City is not yet using these new wells because of sand pro-
blems.  The five original Fort Union wells range in depth from 930 to 1,215
feet and have a total pumping capacity of 310 gpm.  In 1976, these wells were
found to be operating at 100 percent capacity  (Nelson et al., 1976).

     In addition, the City has three wells drilled into the Fox Hills
Formation.  They range in depth from 3,479 to 8,505 feet and have a total
rated capacity of 575 gpm for two of them and a rated capacity of 75 gpm
for the third.  Two of the wells (#1 and #2) have been plugged back and
perforated in the Fort Union Formation.

     The  City of Gillette  has recently  turned  its attention to  the  Madison  For-
mation as  a  potential municipal water supply.  Although the Madison limestone
is  found  at  about 11,000 feet below the ground surface  in  the Gillette area, it
is  considerably closer to  the surface east of  Gillette.   In July  1977, Pacific
Power and  Light Company, the  Joint Powers Board of Campbell County, and the City
of  Gillette  jointly began  drilling a test well in the Madison Formation 10 miles
northwest  of Keyhole  Reservoir.  The well was  drilled to  2,625  feet, and water
rose to within 400 feet of the surface.   If  production  and quality  are found to
be  suitable, the City of Gillette has the option of developing  a  well field on
40  acres  around this  site.  The City would then construct  a pipeline to
Gillette,  a  distance  of about 50 miles.

Subdivisions and Trailer Courts

     Subdivisions and trailer courts are  springing up around the  periphery of
Gillette.  Rather than hooking up to the  City  distribution system,  these new
developments are drilling  their own wells.   As of November 1976,  records from
the State  Engineer's  Office showed that water  rights permits had  been granted
to 26 subdivisions and trailer parks for  a total of 4,650  acre-feet annually
(afa).

RURAL DOMESTIC USAGE

     Campbell County now has a rural population of about 2,000.   Again, on  the
basis of a typical household usage of about  105 gallons per capita  per day, usage
is roughly 210,000 gallons per day (gpd).

     The State Engineer has on file water rights permits  for 238  domestic wells
in the project area.  Most of the wells range  from 100  to  500 feet  in depth,
with three wells over 1,000 feet deep,  and yields vary  between  2  and 25 gpm.

                                      75

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 INDUSTRIAL USAGE

 Coal Strip Mining

      The major  use  of water at the mines is for road dust suppression.  Other
 uses include  drinking, bathing, etc., and equipment wash  water.   All of the
 mines will be obtaining water both from pit discharge  and from deep wells.
 Table 4-1 summarizes water requirements for dust suppression and cleaning/
 domestic usage.
                   TABLE 4-1.  MAJOR MIME SITE  WATER USAGE
Mine
AMAX Belle Ayr South
AMAX Eagle Butte
ARCO Black Thunder

Carter North Rawhide


Dust suppression
(gallons per day)
80,000
(sunnier)
100,000
50,000 - 225,000

200,000
(summer)

Source
pit discharge
pit discharge
pit discharge
and settling
pond
mine drainage
and sewage
treated efflu-
ent
Cleaning/domestic
(gallons per day)
2,500 - 4,000
(wash house only)
55,000
60.000 - 100.000

31,000


Source
local wells
deep wells
4 wel 1 s

1 well


   Kerr-McGee Jacobs Ranch

   Sun Oil Cordero




   Wyodak
   100,000

   350,000
(storage tank)
   60,000
pit discharge

pit discharge
and package
treatment plant
effluent

pit discharge
   15,000
(domestic only)
   10,000
(domestic only)
wells 300 to
1,000 feet deep
9 wells in Fort
Union Formation
      Water requirements for dust  suppression vary seasonally with  peak water
 usage during the summer months.   In  addition, extremely heavy  traffic or wind
 conditions can increase water demands.   Excess industrial water  during the
 winter months will be pumped into  holding tanks or mine settling ponds   The
 U.S.  Geological Survey (1975) states that excess pit discharge from AMAX's
 Belle Ayr South mine will be diverted to Donkey Creek.

      Water for cleaning and domestic purposes is being supplied  by local ground-
 water wells.   This includes water  for plant wash, steam cleaning,  and personal
 usage.   AMAX estimates personal usage to be about 50 gpd per employee.

 Steam Electric  Power Generation

      Although both the operating power plant and the one under construction are
designed  to  be  air-cooled, water losses  occur in the following areas:  boiler
blowdown,  dermneralizer,  evaporation from ash pond, sanitary wastes, equipment
wash  water, and  floor and equipment  drainage.  Anticipated water requirements
for the two power  plants  are 200 to  300  gpm.   The current source of water is
from wells in the  Fort Union and Fox Hills Formations.  When the new plant goes
                                       76

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 on  line  in  June  1978,  the major water  supply will  be  treated  sewage effluent.
 from  the Gillette  sewage treatment  plant  (Black Hills Power and Light  Co.,  1973).

 Coal  Gasification

      Lawrence  Livermore Laboratories is currently  conducting  in situ coal gasi-
 fication experiments at the Hoe Creek  site  south of Gillette.  The first experi-
 ment,  carried  out  in October  1976,  produced 66,067 gallons of water from the
 dewatering  wells beyond that  actually  used  in the  gasification process.  In
 addition, half of  that amount again was produced as steam.  It is not  known at
 this  time how  the  excess water is disposed  of (Lawrence Livermore Laboratory.
 1977).

 Secondary Oil  Recovery

      According to  the  U.S. Bureau of Land Management  (1974), estimated ground-
 water used  for secondary oil  recovery, exclusive of oil produced water, in
 Campbell  County  was 8,500 acre-feet in 1973.  Little  change was expected for
 the future.  In  northeastern  Campbell  County, water is obtained mostly from
 Inyan Kara  rocks and the Minnelusa  Formation; while in southeastern and western
 Campbell  County, most  of the  secondary recovery water comes from the Fort Union
 and Lance Formations and the  Fox Hills sandstone.

 AGRICULTURAL USAGE

      Agricultural  water usage consists primarily of stock watering, with minor
 irrigation.  As  of November 1976, water rights permits were on file with the
 State  Engineer for 439 stock  wells  in the project area.  These range in depth
 from  1 to 640  feet, with the  majority between 10 and  200 feet.  The yields are
 mostly under 10  gpm, but range from 2 to 100 gpm.  There are also 129 combined
 stock  and domestic wells, 5 stock and irrigation wells, and 12 wells combining
 stock  watering with commercial or industrial uses.  In the last case, water is
 sold  for construction, oil exploration, or other purposes.

     The Wyoming Water Planning Program (1973) stated that in Campbell County
 consumptive water  use  can be  assumed to be approximately 15 gpd for cattle and
 3 gpd  for sheep.   The  Wyoming Department of Agriculture (personal  communica-
 tion)  reported that as of January 1976, there were 85,000 cattle and calves
 and 84,000 sheep in Campbell   County.  Using these figures, total  water consump-
 tion for stock watering in Campbell  County is approximately 1.5 mgd.  Roughly
 60  percent of  this total is provided by groundwater.  Therefore,  a rough esti-
 mate of groundwater used for  stock  watering in Campbell County is 0.9 mgd.

     Records from  the  State Engineer's Office (November 1976) show nine irriga-
 tion wells in  the project area.   Most of these are used by schools, cemeteries,
etc.,  and have yields  ranging from  30 to 100 gpm.  Two of the wells are agri-
cultural  and have yields of 600 and 350 gpm.  There are also five wells used
for both irrigation and stock watering.  These have yields ranging from 20 to
200 gpm.
                                     77

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                                   SECTION  5

                            HYDROGEOLOGIC FRAMEWORK
      This  section is intended to provide the source-specific background infor-
 mation  for the hydrogeologic framework upon which the various potential pollu-
 tion  sources  identified in Section 2 are to be superimposed.  Data and infor-
 mation  gaps exist for many individual sources.  These gaps will need to be
 filled  before a  complete assessment of the potential impact of these sources
 on groundwater quality can be made.

      The section has been arranged according to five major interest areas -
 surface water hydrology, soils, geology, existing hydrogeology, and the modi-
 fied  hydrogeologic  practices of the coal strip mining firms.  The order of
 these areas of interest is of significance because, as the potential pollu-
 tants enter the  system, they are usually subject to the influence of at least
 one of  these  interest  areas.

 SURFACE WATER HYDROLOGY

      This  discussion covers the surface hydrology and its relation to ground-
 water in the  study  area at present.  Conditions during and after mining will
 also  be discussed in the general framework.  A detailed site-specific treat-
 ment  of surface  hydrology cannot be made until the mines provide complete
 access  to  their  hydrologic data.

 Precipitation and Evapotranspiration

      The Powder  River Basin is semi arid.  Average annual rainfall is 15 inches;
 average potential evapotranspiration is 25 to 30 inches.  Rainfall varies
 widely  from year to year and is distributed unevenly during the year.  Most
 rain  comes  from  thunderstorms in the spring and early summer.  Thunderstorm
 rainfall is very localized, intense, and of short duration.

      Little naturally occurring surface water is found in the  basin.  Most
 rain  received in the basin is carried back to the atmosphere by evapotrans-
 piration.   Only  a small portion runs off as streamflow, or moves deep  into
 the subsurface to recharge aquifers.  Some small, shallow intermittent lakes
 can be  found after rainfall.  Only the Belle Fourche River and two of  its
 tributaries, Donkey and Caballo Creeks, flow for extended periods of time
during  the year.

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Watershed and Stream Morphology

     The topography of the eastern Powder River Basin is gently rolling.
Surface relief varies from east to west, particularly east of the coal burn
line that marks the boundary between the Wasatch and Fort Union Formations.
Elevations in the basin range from 4,500 to 5,000 feet.

      Figure  5-1  shows  the  area  selected  for the monitoring study and  the
major watersheds intersected  by the monitoring area.  The monitoring  area
was  arbitrarily  divided  into  five watersheds:  Rawhide  Creek, which flows  to
the  Powder River;  the  Belle Fourche River and two of  its tributaries, Caballo
and  Donkey Creeks;  and Little Thunder  Creek, which  flows to  the Cheyenne River.

      Drainage net  structure appears to be dendritic.  The basin has two re-
gional  joint sets  trending northwest and northeast  and, in some areas, drain-
age  net development appears to  slightly  favor these directions.  Major stream
gradients are gentle.  As  an  example,  the Belle Fourche River has a gradient
of 8 feet per mile just  west  of the Sun  Oil Cordero lease.

      Streams generally occupy grassy swales or narrow floodplains.  Meander-
ing  is very  well  developed on all but  the smallest  streams and meander scars
are  conspicuous  in aerial  photographs.   Dry stream  beds are  grass covered
and  appear to contain  little  moveable  coarse material.

      Intermittent  lakes  that  mark areas  of internal drainage occur on all
watersheds.   Numerous  stock water impoundments  (stock tanks) are also con-
structed along smaller streams. Several stream reaches contain sequences  of
closely spaced tanks.

      The northern third  of Campbell  County  is a  deeply dissected  upland, with
a similar but less severely  eroded  continuation  of  this upland  occupying the
western side of  the County (number 4 in  Figure 5-2).  The relief of this
dissected area is  rolling  to  steep and broken, with numerous butte-like hills
of scoria characterizing this upland.   The entire area  of this physiographic
division is  drained by the Powder River, the Little Powder River, and their
tributaries.

      South and east of the deeply dissected upland  is a rolling divide  (num-
ber  1 in Figure  5-2),  the  crest of which parallels  the  north-south Highway 59.
This area in 'the central and  southern  parts, as well  as the  Rochelle  Hills
(number 2 in Figure 5-2),  which border the eastern  edge of this rolling di-
vide,  are drained  by the Belle  Fourche River and tributaries of the South
Fork Cheyenne River.   The  predominantly  gently sloping  plains and tablelands
of this rolling  divide have local relief of 200 feet  to 400  feet, with  rem-
nants  of the old Missouri  Plateau rising sharply from 100 to more than  1,000
feet about the divide.

      East of the rolling divide is a broad, rough,  broken, and in places,
badlandlike  escarpment that is  locally called the Rochelle Hills  (number 2
in Figure 5-2).   It was  formed  by the  burning of Wyodak coal in the outcrop,
which  protected  the underlying  Fort Union strata, thus  forming this striking
and  prominent  flat-topped  ridge (U.S.  Geological Survey, 1974a).

                                     79

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                                                 LEGEND
                                             	 WATERSHED
                                                BOUNDARY

                                                EPHEMERAL OR
                                                INTERMITTENT
                                             """ STREAM

                                                INTERMITTENT
                                             — OR PERENNIAL
                                                STREAM

                                                MONITORING
                                                AREA

                                             gi PROJECT COAL
                                                LEASE AREAS

                                             1  CARTER NORTH
                                                RAWHIDE

                                             2  AMAX EAGLE
                                                BUTTE

                                             3  WYODAK

                                             4  AMAX BELLE
                                                AYR

                                             5  SUN OIL
                                                CORDERO

                                             6  KERRMcGEE
                                                JACOBS
                                                RANCH

                                             7  ARCO BLACK
                                                THUNDER
Figure  5-1.  Watershed  map.

             80

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                                      ^  Murky jMiint
                                        	|
Figure 5-2.  Physiographic divisions and drainage of
             Campbell County, Wyo.:  (1) rolling di-
             vide; (2) Roche!le Hills escarpment;
             (3) eastward sloping plain; (4) deeply
             dissected upland (Soil Conservation
             Service, 1939).
                        81

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      The  Rochelle  escarpment drops 300  to 400 feet to a relatively  low east-
 ward  sloping  plane (number  3 in  Figure  5-2).  Streams are well entrenched
 throughout  this  plain,  but  the land  is  severely dissected only in local  areas.
 On the whole,  the  surface is gently  rolling, but  it  is modified  in  places  by
 steep valley  slopes and a few rough  broken areas.

      Areas  of alluvial  lands border  most of the larger and many  of  the smaller
 drainage  ways in the four physiographic divisions already described.  Areas
 along the Powder,  the Little Powder, and the Belle Fourche Rivers attain a
 width exceeding  3  miles in  some  locations.

      The  alluvial  lands include  both alluvial terraces and floodplains.  Ter-
 races occupy  about 70 percent of the alluvial lands, having  been formed  before
 streams became so  deeply entrenched.  Some of the higher terraces are gently
 sloping and partly covered  by alluvial  fans built up by deposits from small
 drains issuing from the uplands.  The lower terraces are nearly  level; few
 of them are more than 30 feet above  the adjoining floodplains.

      These varying physiographic divisions within Campbell County produce
 varying soil  properties of  which the following are commonly  found to be  re-
 lief related:  (1) depth of the  solum;  (2) thickness and organic matter  con-
 tent of the A horizon;  (3)  relative  moisture content of the  profile;  (4) color
 of the profile;  (5) degree  of horizon differentiation; (6) soil  reaction;
 (7) soluble salt content;  (8) kind and  degree of  "pan" development; (9)  temp-
 erature;  and  (10)  character of the initial material  (Buol et a!., 1973).
 Undoubtedly,  several of these factors have contributed to soil develop-
 ment in Campbell County.

 Intermittent  Lakes

      Areas  of internal  drainage  to small closed basins occur in  all water-
 sheds in  the  project area.  During heavy or long duration rains, surface run-
 off collects  in  these basins to  form shallow ponds or lakes. The lakes  are
 intermittent  because they quickly dry as water is lost by evaporation.

      The  areal distribution of intermittent lakes shows a pattern that fol-
 lows  the  occurrence of  shallow,  strippable coal.  They tend  to occur where
 the Wasatch beds overlying  the Fort  Union coals are  thin and they show a
 trend  that  follows the  coal "outcrop."

      These  small closed basins have  probably been formed by  subsidence.  The
 mechanism causing  subsidence is  believed to be compaction  (diagenesis) of  the
 thick  coal  seams during recent geologic time.  This  explanation  is  supported
 by  the obvious correlation  between the  location of these basins  and the  thick,
 shallow coal beds.

     Because these  basins do not  drain, salts brought in by  runoff  concen-
 trate  at  the surface  and in the  soil.   Soil maps  show many of these basins
contain a highly alkaline and sodic  acid called McKenzie clay.   These  soils
may contribute to  the deterioration  of  groundwater quality when  disturbed
by mining.
                                     82

-------
     Recharge from intermittent lakes  is probably insignificant.  The soils
in the lake basins have a clay content and are often sodic, which probably
has the effect of sealing the basin floors when water ponds on these soils.

Streamflow Characteristics

     Streams may be classed as ephemeral, intermittent, or perennial.  Ephem-
eral streams are dry except for very brief periods when they flow in response
to heavy rainfall, which is usually caused by intense, short-duration thunder-
storms.  Intermittent streams flow for extended periods during the year but
are dry for some period, usually during the summer when evapotranspiration
rates are high and there is little or  no rain.  Perennial streams flow through-
out the year.

     Virtually all streams in the area are ephemeral or intermittent.  Peren-
nial flow occurs only during wet years in the lower reaches of the Belle
Fourche River, the largest stream in the project area.  Figure 5-3 shows a
flow-duration curve for the 'Belle Fourche at Moorcroft, just east of the
project area.  This curve shows, for example, that discharge is greater than
0.5 cubic feet per second (ft3/s) only 40 percent of the time.

     Streamflow is variable and unpredictable.  Mean values of discharge and
peak flow return periods are obtained  from sparse data and are almost useless
for prediction.  The best and most up-to-date work on Streamflow characteris-
tics is by Lowham (1976), who is the source for Figures 5-4 and 5-5.  The
figures show discharge-drainage area relations for streams in two hydrologic
regions that occur in the monitoring area.  These regions are shown in Figure
5-6.

     Lowham1s (1976) graphs give mean  annual discharge (Qa) and peak discharge
for various return periods (PI00 = peak with 100-year return period).  He
states that these graphs are not applicable where stream characteristics have
been altered by man and a few data discussed next suggest that streamflows
in the monitoring area have been greatly altered by stock watering tanks.

     By storing water the tanks reduce runoff volumes.  At AMAX Eagle Butte,
discharge in the Little Rawhide Creek  where it enters and leaves the lease
was 110 and 85 acre-feet respectively  for the period March 1974 to June 1975
(U.S. Geological Survey, 1976).  Note  that flow volume decreased in the down-
stream direction.  Based on drainage areas at these two points, Lowham's
graphs for Region 3 (Figure 5-5) give  mean annual flow volumes of 1,800 and
2,200 acre-feet.  Aerial photos of the Little Rawhide Creek watershed upstream
of the lease show at least 31 stock tanks in the 22-square-mile drainage area,
and their presence may explain the very large difference between the estimated
and observed flow volumes.

     Stock tanks are found in great numbers throughout the monitoring area.
Streamflow records at other mine sites also show flow volumes that are much
lower than Lowham's estimates.  Lowham's graphs give a mean discharge of 8
ft3/s for the Belle Fourche at Sun Oil  Cordero, but the Cordero Mining Co.
(1976) reports-that the river is dry for long periods and normally flows at
less than 5 ft /s.

                                     83

-------
                              Ploins   streams
          10,000
        O
        2
        O
        O
        UJ
        V)
        UJ
        UJ
        O
        CD

        O
        1U
        O
        cc
        <
        x
        O
        V)
          1,000
            too
                         J	I
  i  i i  I—n—[—i—rj	r

(FlOCiJ'lOOO  Lime Missouri River
     neor AlzOdO , Mont.

fGlOC38G500 Cheyenne River neor
     Sr-wrer.

fH)OG396000 Lonce CreeK ol
     Spencer.

rno6"2GbOO  Se'ie Furche River
     below Moorcroft.

(T)063r»«000 Beaver CreeK neor
     Newcastle.
              • Ol  .1     I      to       SO     SO     3$  ??9 9999

              PERCENTAGE OF TIME  DISCHARGE  WAS  EQUALED

                               OR EXCEEDED.
Figure 5-3.   Flow  duration curves for  selected Wyoming  streams
               (U.S.  Bureau of Land Management, 1974).
                                   84

-------
                   DRAINAGE AREA, IN SQUARE KILOMETERS
  50,000
  10,000
o
o
UJ
CO

ce.
    1000
CO
=3
O
oc

-------
                   DRAINAGE  AREA,  IN  SQUARE KILOMETERS

                    5  10       50  100      5001000    500010,000
  50,000
  10,000 r
o
o
UJ
a:
UJ
CO
3

O
C3
Q£
to
I—t
a
    1000 r
I 'I I Mill	1—I I  I Ilil
                1            10          100          1000
                    DRAINAGE AREA,  IN  SQUARE  MILES
                                                        10,000
 Figure  5-5.   Relations  for estimating flow characteristics  in  region  3
              by  using drainage area  (from Lowham,  1976).
                                  86

-------
                 GILLETTE  V^V*^
                    I 	  y"T*DONKEY
  LEGEND

 BOUNDARY LINE
 BETWEEN EPHEMERAL
 AND INTERMITTENT
 STREAMS

 WATERSHED
 BOUNDARY

 EPHEMERAL OR
- INTERMITTENT
 STREAM

 INTERMITTENT
 OR PERENNIAL
 STREAM

 MONITORING
 AREA

 PROJECT COAL
 LEASE AREAS
                                                       1  CARTER NORTH
                                                         RAWHIDE

                                                       2  AMAX EAGLE
                                                         BUTTE

                                                       3  WYODAK

                                                       4  AMAX BELLE
                                                         AYR

                                                       5  SUN OIL
                                                         CORDERO

                                                       6  KERRMcGEE
                                                         JACOBS
                                                         RANCH

                                                       7  ARCO BLACK
                                                         THUNDER
Figure 5-6.   Hydro!ogic regions  at monitoring area.
                            87

-------
Surface Water Quality

     Surface water  is  sampled for chemical  quality at  several locations in
the Powder River Basin by the U.S. Geological  Survey.   Sampling  sites and
type of analysis are shown in Figure 5-7.   No  sites are located  within the
monitoring area.
          t
                          106°,
                              106324500
                                           105"
                                 	•      .
                                ~
                               20
                                      40      60
                                      SCALE (miles)
                                                    80
                                                           100
                           i    MONITORING AREA


                           -•   09234500 CHEMICAL-MEASUREMENT SITE

                           ••  09234500 TEMPERATURE.MEASUREMENTSITE

                           i   09217000 BIOLOGICAL-MEASUREMENT SITE

                           f   09217000 SEDIMENT -MEASUREMENT SITE
      Figure  5-7.  Surface water  quality measurement  sites (adapted from
                    Water Resources  Data for Wyoming,  Part 2.   Water
                    Quality Records, U.S. Geological Survey, 1974a).
                                        88

-------
     To show  the  range of  constituents  included in a  chemical  analysis,
results from  station  06428500  on  the  Belle Fourche River  for 1974 are shown
in Table 5-1.  During this year,  dissolved solids  concentration  ranged from
about 750 to  2,000  ppm.  The major dissolved  constituent  was sulfate, which
ranged from 450 to  1,300 ppm.   Calcium  and bicarbonate were next in abun-
dance.  Their concentrations,  which tended to be about equal,  ranged from
100 to 400 ppm.

     Surface  water  quality is  also reported for streams on several mine
lease sites in environmental impact studies where  quality data have been
collected as  part of  a program to gather  baseline  information.  Their analysis
generally shows sulfate as the major  dissolved solids constituent followed by
calcium, bicarbonate  and,  in some cases,  sodium.

Surface Mater—Groundwater Relationships

     Strip mining of  coal  may  have a  great impact  on shallow groundwater sys-
tems.  The occurrence and  movement of groundwater  in these systems is directly
related to the surface hydrology.   This is the case both  under natural  condi-
tions which prevail at the present and  under  modified conditions that will
occur during  and  after stripping  of the coal.

     A general picture of  the  relationship between surface water and ground-
water is provided by  the streamflow characteristics of the project area.
Ephemeral streams lose water to the streambed and  are sources of recharge to
groundwater.  Intermittent streams lose water at certain  times and receive
groundwater at others.  They are  alternatively sources of recharge and points
of groundwater discharge.  Discharge  of groundwater to intermittent streams
is often not  sufficient to cause  flow but may provide enough water to sustain
ponds in the  streambed.  Perennial  streams are points of  groundwater dis-
charge at all times.

     Streams  in the project area  generally grade from ephemeral to perennial
with increasing watershed  size.   Higher elevations on the watershed are areas
of recharge,  both in  ephemeral  streams  and in interstream areas.  Recharge
along stream  channels is probably  enhanced by seepage from stock tanks.  Seep-
age takes place both  through the  tank bottom  and often through the face of
the dam, which causes water to pond in  the channel for some distance down-
stream from the dam face.

     At lower elevations on larger watersheds,  groundwater may discharge to
streams and sustain intermittent  or perennial  flow.  Perennial flow appears
only on large watersheds.  The largest watershed in the project area, the
Belle Fourche River,  has intermittent flow at the  Sun Oil Cordero lease where
the drainage area is  about 500 square miles.

     Relative quantitives  of runoff and recharge under premining conditions
in the basin are  poorly defined.   Lowham's (1976)  drainage area-discharge
relations for Region  3 (Figure 5-5) give  mean annual runoff values for 10-
and 100-square-mile areas  at 1.6  and  5.5  ft3/s or  2.1 and 0.7  inches.  As
indicated earlier,  these values are likely to be high.  Smith  (1974) esti-
mates average annual  headwater runoff to  be 0.3 inch.  Runoff at the AMAX

                                    89

-------
TABLE 5-1.    REPRESENTATIVE  CHEMICAL  MEASUREMENTS FOR  SURFACE WATER QUALITY  (U.S.  Geological  Survey,  1974a)

                                                        CHEYENNE  RIVER  BASIN
                          06428500   BELLE  FOURCHE RIVER AT WYOMING-SOUTH  DAKOTA STATE  LINE
              LOCATION.   Lat 44°44'59", in NEWMtlWV sec. 18, T.9 N., R.I E..  Butte County, S. Dak., at county bridge,  4.0 mi  northwest of Belle Fourche,
                        S. Dak., and 8.0 mi downstream from gaging station.
              DRAINAGE AREA.  3,280 mi2, approximately (at gaging station).

              PERIOD OF  RECORD.  Chemical analyses:  October 1965 to September 1974. Water temperatures:  October 1965 to September 1974.
              EXTREMES:   1973-1974:
                         Specific Conductance -Maximum daily observed, 2,620 micromhos Jan. 14; minimum  daily,  726 micromhos Mar. 6.
                         Water Temperatures -Maximum, 31.0°C June 19; minimum, freezing point on many days during November to March.
                        Period  of Record:
                         Specific Conductance -Maximum daily, 2,840 micromhos Jan 17, 1970; minimum daily, 461  micromhos Apr. 12, 1971.
                         Water Temperatures -Maximum, 31.0°C June 19, 1974;  minimum freezing point on many days during winter period.
CHEMICAL ANALYSES, WATER YEAR OCTOBER 1973 TO SEPTEMBER 1974
Date
Oct.
24...
Nov..
15...
Dec.
06...
Jan.
10...
Feb.
14...
Mar.
14...
Apr.
25...
May
08...
June
06...
July
04...
Aug.
08...
Sep.
12...
Instantaneous
Time discharge
(cfs)
0800
0800
1410
1700
1710
1315
1715
1815
1000
0900
1415
0900
34
53
35a
8.0a
80a
122-
229
106
67
133
106
33
Dissolved
silica
(SiO?)
(mg/T)
7.0
9.8
11
13
11
8.6
10
15
8.0
6.3
5.3
4.5
Dissolved
Calcium
(Ca)
(mg/1)
230
220
260
370
250
170
130
190
215
130
99
170
Dissolved
Magnesium
(Mg)
(mg/1)
75
66
93
110
38
47
38
57
74
29
34
63
Dissolved
sodium
(Na)
(mg/1 )
92
70
96
140
79
50
50
68
100
100
98
110
Dissolved
Potassium
(K)
(mg/1)
7.7
6.7
7.4
9.5
7.7
8.6
6.7
6.3
8.6
6.7
7.4
8.4
Bicarbonate
(HC03)
(mg/T)
174
203
235
378
215
185
170
207
183
122
189
210
Cirbonate
I Oh)
(mj/1 )
0
0
0
0
0
0
0
0
0
0
0
0
Dissolved Dissolved Dissolved
sulfate chloride fluoride
(S04) (Cl) (F)
(mg/1) (mg/1) (mg/1)
910
790
1000
1300
770
570
440
660
900
550
430
740
4.6
5.5
7.6
9.2
5.3
6.1
'3.8
3.8
3.6
5.4
7.3
7.3
0.7
0.7
0.7
0.8
0.6
0.5
0.6
0.6
0.7
0.7
0.6
0.7
              aDaily mean discharge.
(continued)

-------
      TABLE 5-1  (continued)
<£>
                                                CHEYENNE  RIVER BASIN
                         06428500  BELLE FOURCHE RIVER AT  WYOMING-SOUTH DAKOTA STATE LINE
Dissolved Total
n»*o n1 trate phosphorus
Date (N) (P)
(mg/1 ) (mg/1 )
°3:.. °-05
"iS:.. o-11 °-°2
Dec- 0 05 0 01
06...
JJQ' 0.11 0.02
Fj4- 0.18 0.04
"^ 0.36 0.01
A^' 0.18 0.02
"Q* 0.07 0.01
Jpge 0.05 0.01
J^y 0.38 0.02
Aol:.. °-°7 °-01
SjP- 0.00 0.00







(sum of
:onstituents)
1410
1270
1610
2160
1260
956
760
1100
1400
890
775
1200

Date
Oct. 24...
Jan. 10...
Apr. 25...
July 04...

Dissolved Dissolved
solids sol Ids
(tons/ (tons/
acre-ft) day)
1.92
1.73
2.19
2.94
1.71
1.30
1.03
1.50
1.90
1.21
1.05
1.63

129
182
152
46.7
272
315
470
315
253
320
222
107
FIELD
Instantaneous
Time discharge
(cfs)
0800
1700
1715
0900
Ale. «.Uiiwi
34
8.0a
229
133

Hardness r,rhona ,e Sodium DH Specific
(Ca,Mg) 'A^™ adsorption , p" , conductance
(mg/1) (mg/f) ratio Iun1ts) (micromhos)
890
830
1000
1400
780
630
480
710
840
440
380
680
DETERMINATIONS
Turbidity
(JTU)
9
3
170
90

750 1.3 8.2 1750
660 1.1 8.2 1610
810 1.3 8.1 1940
1100 1.6 7.9 2470
600 1.2 8.0 1570
480 0.9 7.9 1260
340 1.0 8.0 1020
540 1.1 8.3 1300
690 1.5 8.2 1730
340 2.1 7.7 1220
230 2.2 8.2 1100
510 1.8 8.2 1510

Dissolved Fecal
oxygen col i form
(mg/1) (col. /100ml)
9.5 110
9.5 10&
7.5 145
7.2 2700

Temperature
rc)
10.5
1.0
0.5
0.0
0.0
6.0
16.0
17.0
15.5
17.5
23.5
10.0







                                      bNon-ideal counting conditions
                                                                                                      (continued)

-------
     TABLE  5-1  (continued)
                          06428500
             CHEYENNE RIVER BASIN
BELLE FOURCHE  RIVER AT WYOMING-SOUTH DAKOTA STATE LINE
ro
DAY
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
IS
20
23
22
23
24
25
26
27
23
29
30
31
MONTH
SPECIFIC CONDUCTANCE (ml crambos/cm AT
OCT NOV DEC JAN FEB
1690
1670
1650
1670
1700
1740
1780
1800
1700
1640
1570
1460
1640
1680
1710
1700
1740
1730
1720
1720
1720
1750
1760
1750
1780
1780
1790
1750
1640
1580
1750
1700
1650
1630
1610
1590
1680
1630
1700
1710
1630
1680
1680
1740
1620
1630
1590
1700
1700
1680
1680
1760
1820
1900
2030
2020
2020
2000
1960
1970
1940
1960
—
1760
1500
1840
1760
1950
1850
1790
1990
1890
1980
1780
1730
1940
1910
1890
1920
1940
1950
1960
1970
1980
1980
1840
1980
1910
1850
1890
1800
1960
1960
1980
2000
1910
2050
2150
2210
2230
2260
2320
2360
2310
2480
2500
2520
2600
2590
2620
1560
1180
1200
1200
1410
993
1110
1060
895
1020
922
926
1000
1020
1130
1230
1250
1690
1280
1370
1360
1330
1410
1460
1530
1600
1640
1680
1580
1660
1600
1550
1590
1490
1470
1500
1480
1440
1390
1100
1200
1120
1160
1090
1100
1300
—
—
—
1410
25-C). HATER YEAR OCTOBER 1973 TO SEPTEHBER 1974
MAR APR HAY JUN JUL AUG
1320
1500
1590
1600
1140
726
870
847
872
983
1120
1190
1240
1260
1380
1400
1420
1470
1520
1600
1680
1670
1610
1650
1720
1640
1640
1620
1670
1750
1710
1400
1700
1730
1700
1730
1720
1680
1620
1720
1700
1700
1660
1550
1600
1700
1730
1720
1700
1620
1620
1450
1380
1510
995
1030
994
1200
1260
1530
1240
1210
—
1520
1260
1330
1370
1440
1430
1440
1450
1450
1510
1470
1510
1550
1450
1570
1620
1640
1650
1730
1680
1660
1670
1660
1680
1830
1670
1680
1700
1650
1740
1750
1760
1580
1880
1740
1640
1620
1540
1740
1740
1760
1860
1840
1820
1830
1800
1780
1820
1870
1940
1940
1840
1880
1670
1820
1850
1970
1890
2000
1980
1890
2050
1980
--
1830
1450
1840
1690
1120
1120
1090
1120
1100
1110
1110
1120
1140
1130
1130
1130
1130
1120
1120
1020
980
920
760
850
990
1080
1110
1140
1110
1120
1120
1130
1130
1130
1120
1120
1110
1100
1000
975
956
1020
1010
985
1070
1060
1060
1040
1070
1090
1140
1150
1190
1240
1220
1220
1210
1210
1240
1280
1320
1290
1360
1480
1140
SEP
1350
1340
1350
1330
1350
1370
1380
1420
1470
1520
1570
1590
1620
1660
1660
1710
1780
1820
1870
1900
1950
1990
1980
2000
2030
2040
2060
2060
2080
2060
-•
1710
                         YEAR: MAX  - 2620; MIN - 726;  MEAN - 1570
                                                                                                    (continued)

-------
     TABLE  5-1  (continued)
                             06428500
                   CHEYENNE RIVER BASIN
     BELLE FOURCHE  RIVER AT  WYOMING-SOUTH DAKOTA STATE LINE
CO
                                           TEMPERATURE (°C) OF WATER, WATER YEAR OCTOBER 1973 TO SEPTEMBER 1974
                                                             (ONCE-DAILY MEASUREMENT)
                               DAY
OCT
                                           NOV
                                                 DEC
                                                        JAN
                                                              FEB
                               MAR
                                                                          APR
                                            MAY
                                                                                       JUN
                                                                                             JUL
AUG
                                                                                                          SEP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
MONTH
19.0
15.0
13.0
14.0
14.0
15.0
15.5
13.0
12.0
5.0
5.0
7.0
12.0
11.0
10.5
14.0
12.0
13.0
14.0
14.0
14.5
14.5
12.0
12.0
11.0
9.0
9.0
7.0
7.0
7.0
6.5
11.5
4.0
3.5
2.5
1.0
0.5
0.5
0.0
0.0
0.0
0.5
2.0
5.0
6.5
5.0
4.5
4.0
6.0
2.0
0.5
0.5
0.0
0.0
0-0
0.0
0.0
0.0
0.0
0.5
0.5
0.0
—
1.5
3.0
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.5
0.5
0.0
0.5
0.0
0.0
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
—
--
—
0.0
0.5
8.0
6.0
8.5
4.0
1.0
3.0
0.5
3.0
3.0
1.0
0.0
1.0
1.0
4.0
2.5
7.0
7.0
1.0
0.5
0.5
0.5
0.5
1.0
2.0
4.0
6.0
8.0
11.0
11.0
8.0
3,5
10.0
7.0
5.5
7.0
8.0
8.0
8.0
10. 6
12.0
8.0
3.0
3.5
5.0
6.0
8.0
8.0
11.0
15.0
15.0
7.0
10.0
12.5
11.0
15.0
16.0
16.0
14.0
13.0
14.0
17.0
--
10.0
18.0
12.0
13.0
15.0
18.0
18.0
18.0
19.0
19.0
18.0
16.0
14.0
12.0
11.0
12.0

10.0
12.0
15.5
17.0
16.0
17.0
17.0
16.0
21.0
23.0
20.0
22.0
14.0
15.0
17.0
16.0
19.0
21.0
22.0
22.0
18.0
20.5
16.5
20.0
18.0
21.0
22.0
25.0
26.0
27.0
27.0
27.0
26.0
30.0
31.0
30.0
30.0
22.0
27.0
27.0
27.0
27.0
27.0
28.0
28.0
28.0
--
24.5
26.0
21.0
21.5
24.0
25.0
24.5
27.0
25.0
28.0
25.0
25.0
25.0
29.5
27.0
27.0
27.0
27.0
27.0
29.0
28.5
28.0
27.0
27.0
27.0
25.0
25.0
26.0
25.0
24.0
24.0
23.0
26.0
22.0
22.0
23.0
23.0
24.0
22.0
20.0
20.0
10.5
20.5
20.0
22.5
20.0
20.0
22.0
22.0
24.5
24.0
24.0
25.0
24.0
23.0
23.0
23.5
25.5
25.6
23.0
21.0
19.0
16.0
16.5
22.0
14.0
16.5
17.5
19.0
18.0
22.0
21.0
17.0
14.0
14.0
14.0
14.0
16.5
18.0
20.0
20.0
19.0
21.0
18..0
25.5
16.0
17.0
17.0
17.5
15.0
15.0
13.0
14.0
15.0
14.0
—
17.0
                                YEAR:  MAX  - 31.0;  MIN - 0.0;  MEAN - 11.0

-------
 Eagle Butte  lease mentioned earlier was 0.09 inch from March 1974 to June
 1975  (100  acre-feet  from 22 square miles).

      Recharge  estimates vary widely.  Lowry (1972) estimates that 10 per-
 cent  of rainfall (1.5  inches) recharges the shallow aquifers.  Rechard and
 Hasfurther (1976) estimate that average annual recharge and runoff do not
 exceed 1 inch.  Other  estimates of recharge range from one percent of pre-
 cipitation (Davis, 1976) to 0.5 inch (U.S. Geological Survey, 1976).

      Relative  quantities of recharge from interstream areas, stream beds,
 and stock  tanks are  now known.  Lowry (1972) believes that most recharge
 takes place  in interstream areas.  He notes that in the spring the soil thaws
 and is "frost  cultivated."  Under this condition, soil permeability is great-
 ly increased and it  is possible that large amounts of water infiltrate during
 the first  spring rains.

      Recharge  through  ephemeral or intermittent stream channels is probably
 significant, especially where well-developed meanders result in stream
 channel  lengths that greatly exceed the length between two points along the
 longitudinal axis of the floodplain.  Recharge by seepage from stock tanks is
 also  likely  to be significant, in particular where they are closely spaced
 along a stream.

      The surface hydrology at specific mines depends in a general sense on
 the position of a site on a watershed.  The watershed area that drains through
 a  mine site  will decrease as the location of the mine approaches the head-
 waters of  the  watershed.  Streamflow is ephemeral for small drainage areas
 and flow volumes are relatively small.  The headwaters of the watershed tend
 to be recharge areas and water tables are relatively deep.  At lower eleva-
 tions on the watershed, Streamflow is intermittent and flow volumes can be
 large; the water table tends to be shallow and groundwater discharges to
 streams  under  wet conditions.

      Four  mines in the monitoring area are located high on their watersheds
 and drainage areas upstream of the sites tend to be small.  These are AMAX
 Eagle Butte  and Carter North Rawhide on the Rawhide Creek watershed and
 ARCO  Black Thunder and Kerr-McGee Jacobs Ranch on Little Thunder Creek water-
 shed  (Figure 5-1).   The mines on Donkey and Caballo Creeks and the Belle
 Fourche  River  watersheds (Figure 5-1) have larger upstream drainage areas.

      Table 5-2 summarizes drainage areas for the lease sites and gives mean
 annual  runoff  and peak discharge for a 25-year period estimated using Lowham's
 (1976) methods.

 SOILS

      This  subsection is intended to provide an insight into the relationship
 of the soil  environment to the hydrogeologic framework of the project area
which  is located within Campbell County.   Good quality soil information  and
data  are paramount to the task of completing a comprehensive environmental
assessment of  the effects of surface coal mining on soil properties.   For  '
example, because soil properties will be completely changed by the mining


                                     94

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<£>
          TABLE  5-2.   DRAINAGE AREAS FOR LEASE SITES,  MEAN ANNUAL  RUNOFF, AND 25-YEAR PEAK DISCHARGE
                      (from Lowham,  1976)

Hydrologic Drainage area Mean annual
region upstream of runoff
Mine (Lowham, 1976) Stream lease (mi2) (ft3/s)
ARCO
Black Thunder
Carter
North Rawhide
AMAX
Eagle Butte
Sun Oil
Kerr-McGee
2
3
3
2
2
Little Thunder Creek
N. Prong Little Thunder Creek
Rawhide Creek
Little Rawhide Creek
Little Rawhide Creek
Dry Fork Little Powder River
Belle Fourche River
N. Prong Little Thunder Creek
58
43
60
30
22
17
494
50
. 2.3
2.0
4.5
3.0
2.6
2.4
8.0
2.0
25-year peak
(ft3/s)
1,500
1,200
3,300
2,800
2,000
1,900
3,000
1,200
     Jacobs Ranch
     Wyodak
Donkey Creek
100
3.1
1,700

-------
 process, knowledge of the premining soil situation is necessary to evaluate
 the  revegetation and infiltration potentials of the spoil material after the
 land has been disturbed.  In some cases, replaced spoil material will be a
 source of pollution by virtue of its high concentration of soluble salts
 which may leach to the groundwater.

 Existing Soil Environment

      Soil formation is largely a function of external processes which alter
 the  parent material of a soil both chemically and physically.  Five major
 factors control the kinds of soil that develop.  These are:  (1) the nature
 of the parent material, including its chemical and mineralogical composition,
 texture, and structure; (2) the climate under which the soil has formed,
 particularly temperature and precipitation; (3) the living organisms which
 interact with the soil, especially the native vegetation;  (4) the topography
 of the area when the soil is formed; and (5) the time that the parent mate-
 rials are subjected to soil formation.

      The soils of Campbell County are mostly residual, formed from weathered
 sedimentary material, mostly sandstone and shale.  In general, soils formed
 from sandstone are of coarse texture (especially in surface horizons), and
 highly permeable.  Soils formed from shales are generally fine textured,
 relatively impermeable, and consequently poorly leached.

      The soils of Campbell County reflect the character of the bedrock to
 a marked degree.  Areas of sandy and medium-textured soils are underlain
 by sandstone and sandy shale, and heavy soils are underlain by clayey sha'le.

      The sandy loam and loam soils absorb moisture readily.  They have fri-
 able or only moderately compact subsoils, and they are thicker than the
 heavy or fine-textured soils.  Surface layers are well supplied with organic
 matter and are neutral or only slightly alkaline.  Lower subsoils are cal-
 careous and are represented by a lime carbonate accumulation at depths of
 16 to 30 inches.

      The gray, heavy clay shale weathers slowly, and the soils developed -
 from it are shallow.  The shallow soils have a medium- to fine-textured
 surface and a dense, compact subsoil.  They absorb moisture slowly, and
 runoff is rapid on the more sloping areas.  On the steeper slopes, little
 or no soil development has taken place due to geologic erosion.

      Soils developed from scoria (clinker) were formed in  the past by the
 burning of thick coal beds of the Fort Union Formation, are characterized
 by a  reddish-brown to a light-red friable surface horizon  and a red or reddish-
 brown friable subsoil containing a layer of lime carbonate accumulation.

     Alluvial soils are developed from a variety of material washed from
 the uplands and high landscapes and redeposited along stream courses.  They
occupy comparatively narrow, elongated, continuous, or broken strips  along
most of the main drainages.  The soils have a grayish-brown to  dark  grayish-
brown friable surface that contains a fair amount of organic matter,  and
they are calcareous at or near the surface.


                                      96

-------
     Miscellaneous areas of soil include rough broken land, rock land, gul-
lied land, and rock outcrops occupying lands of steep relief characterized
by exposed beds of sandstone, shale, and clinker.  A complex soil pattern
occurs as residual soils between the dissections.  The forces of nature are
the controlling factors of these landscapes.

     The natural vegetation of Campbell County is mainly short grasses com-
mon to much of the northern part of the Great Plains region.  Some areas in
the northern and eastern parts of the County support variable stands of trees.
Grass is generally more luxuriant and abundant in the northern than in the
southern part of the County due to the slightly greater precipitation in the
north.  Also, grass grows better on the sandy soils than silty or clayey
soils, and better on the smooth areas than on those steeply sloping.  Due
to the semiarid climate and vegetative conditions, organic matter is accumu-
lated slowly, and soils have developed light-colored surfaces.

Classification of Soil Series of Campbell County-

     The present classifications of all soil series published in the 1939
reconnaissance soil survey of Campbell County have been determined, and are
included in Table 5-3.  As more detailed soil mapping is completed by indi-
vidual mines, new series are expected to be identified in the County, and
the classifications of these series will be included in a subsequent report.

     The majority of soil acreage of Campbell County belongs to the soil order
aridisols.  These are primarily soils of dry places, with an achric epipedon
(light-colored surface horizon), with one or more additional diagnostic sub-
surface horizons.  The climatic regime in which aridisols form can be charac-
terized as one in which the potential evapotranspiration greatly exceeds the
precipitation during most of the year and no water percolates through the
soil.

     Because of the limited amount of water available in the profile, the
chemical and physical reactions which are important in aridisol profiles
are relatively less intense than those in humid regions.  Because of this,
the soils inherit much of their morphology from the parent material and the
lack of leaching has left the profiles with a high base status.

     The aridisols are separated  from the  Inceptisols, soils with one or
more diagnostic horizons that are thought to form rather quickly, and that
do not represent significant illuviation, eluviation, or extreme weathering,
by the circumstance that unless irrigated they are usually dry or have a
saturated extract conductivity or more than 2 mmhos/cm at 25° C in the 18-
to 50-cm layer (Buol et al., 1973).

     The occurrence of an argillic  (clay) subsurface horizon relates to age
and position on the landscape as well as to soil management.  The presence
or absence or an argillic horizon in aridisols is used as the basis  for di-
viding the order into two suborders, argids  (with argillic horizons) and
orthids (without argillic horizons).
                                     97

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        TABLE 5-3.  SOIL SERIES CLASSIFICATION OF CAMPBELL COUNTY
                    (after Soil Conservation Service, 1939)
   Soil Series
            Soil Classification
Arvada
Banks
Bridgeport
Di11i nger
Fort Col\ins
Goshen
Laurel
McKenzie

Manvel

Pierre

Renohill
Rough Broken Land

Sarpy
Searing
Terry
Ulm
Wibaux
Ustollic Natrargid, fine, montmorillonitic, mesic
Ustic Torriofluvent, sandy, mixed, calcareous mesic
Fluventic Hapustoll, fine-silty, mixed, mesic
Pachic Hapustoll, fine-loamy, mixed, mesic
Ustollic Haplargid, fine-loamy, mixed, mesic
Pachic Arguistoll, fine-silty, mixed, mesic
Aquollic Salorthid, fine-loamy, mixed, mesic
Typic Haplaquept, fine, montmorillonitic (calcare-
ous), frigid
Ustic Torriorthenth, fine-silty, mixed (calcareous),
mesic
Usteric Camborthid, very-fine, montmorillonitic,
mesic
Ustollic Haplargid, fine, montmorillonitic, mesic
                              «
Unclassified and Ustic Torriorthenths, loamy and
clayey, montmoriHorn'tic, calcareous, mesic and
shallow
Typic Udipsamment, mixed, mesic
Ustollic Haplargid, fine-loamy, mixed mesic
Ustollic Haplargid, coarse-loamy, mixed, mesic
Ustollic Haplargid, fine-loamy, mixed, mesic
Ustic Torriorthenth, loamy-skeletal over fragmental,
mixed mesic
                                  98

-------
      The argids have formed on the oldest geomorphic surfaces, as on the
 crests  of alluvial  fans.  Orthids are found on geologically younger side
 slopes  and surfaces of intermediate age (Figure 5-8).  Soils of the young-
 est surfaces in the dry region, both the steep mountain slopes and recent
 alluvial bottoms, have not developed any diagnostic subsurface horizons and
 are classified as entisols.
                                          PALEARGIOS
                                          and HAPLUSTOLLS
                                                          LITHIC
                                                          HAPLORTHENTS
                                     PALEARGIDS
                        HAPLARGIOS
                        andKAPLORTHIDS
              HAPLORTH1DS

            River

               5

          NATRARGIDS'
                           TORRIFLUVENTS HAPLORTHIDS
         Figure 5-8.   Block diagram showing positions of some major
                      kinds of aridisols and their associates (after
                      Buol et al., 1973).

Major Soil Associations  of Campbell  County-

     The nature of soil  associations is basically a grouping of soils similar
to each other  according  to pattern and position and not on the basis of capa-
bility or expected response.   Soil  associations are named according to the
dominant soil  series  occurring within the delineations.  Figure 5-9 illus-
trates 10 of these associations.

     The soil  survey  of  Campbell  County separates soils into six groups for
purposes of discussion,  based on  the soils'  position on the landscape and the
parent material from  which they were derived.   Their divisions include:  soils
of the uplands and terraces derived from sandy and slightly silty shales; soils
of the uplands and terraces derived from gray  clayey shales and clays; soils of
the uplands and terraces derived  from dark-gray Pierre shale; soils of the
uplands derived from  sandstone; soils of the uplands and terraces derived from
red, burned shale (scoria); and soils of the bottom lands.

     Soils of the uplands  and terraces derived from sandy and slightly silty
shales-The soils  of  this group include the Ulm,  Fort  Collins,  Goshen,  and
                                       99

-------
           R76W  I R75W |  R74W [  R7JW  |  R72W |  R71W |  R70W  | R&9W
                              MONTANA
        T
        42
                                                          LEGEND
                                                       ||NT
                                                          ULM-RENOHiLL
                                                           mm
                                                         WiBAUX-SEARiNG
                                                         ARVAOA RENOHILL
                                                         MANVEL MOLING-

                                                          RENOHILL-ULM
                                                          PIERRE-ORMAN
                                                           d]
                                                          ARVAOA-LAUREL
                                                          BRlDGEPORT-

                                                          BANKS-SARPY
                                                            ROUGH
                                                          BROKEN UNO
           R76W |  R75W  [  R74W  | R73W  | R72W |  R71W |  R70W  |  R69W
Figure  5-9.   Soil associations of Campbell  County,  Wyoming
                 (Soil  Conservation  Service,  1939).
                                   100

-------
Bridgeport, which occupy undulating to gently rolling uplands, colluvial
slopes, and nearly level stream terraces.  All of them are loamy or slightly
sandy in their surface layers, and they are friable and silty or only moderate-
ly clayey in their subsoils.

     Soils of the uplands and terraces derived from gray clayey shales and
clays-The  soils  of  this  group-the Renohill, Arvada, Manvel, Moline, and
McKenzie-occupy  upland areas  that are underlain  by  moderately  heavy clayey
shale, as well as stream terraces and upland slopes and depressions consisting
of alluvium washed chiefly from areas of heavy upland soils.

     Renohill soil occupies 24.5 percent of the County.  It has a light-
colored, moderately friable surface horizon with a somewhat heavy compact,
slowly permeable subsoil.  Arvada soil occupies 4.2 percent of the County and
has a clay pan which causes slow external and internal natural  drainage.  The
McKenzie soil has no surface drainage and occupies playas throughout the
County.

     Soils of the uplands and terraces derived from dark-gray Pierre shale-
The Pierre and Orman are the only soils in this group.  They occupy only a
small acreage in the northeastern corner of the County near Rocky Point.  The
internal drainage of these soils is very slow, due to a very dense, compact
clay subsoil.  Free calcium carbonate ranges from 6 to 15 inches because of
this slow drainage.   This area is shown in Figure 5-9 as the Pierre-Orman
Association.

     Soils of the uplands derived from sandstone-The  Terry is  the only  soil
series in this group.   Terry soil occupies large areas in the central  and
southern parts of the County and, subsequently,  occupies a fair amount of
acreage on some of the mine lease sites.   It has a moderately sandy to sandy
surface horizon and a sandy subsoil.   Due to its rapid internal drainage, it
is leached of calcium carbonate to a  depth of 25 to  50 inches.

     Soils of the uplands and terraces derived from  red,  burned shale  (scoria)-
The soils of this group include the Searing, Wibaux, and Oil linger.  They have
formed from scoria,  the red, burned shale that resulted from the burning of
thick coal  beds of the Fort Union Formation in the past.

     The soils are friable and generally shallow to  bedrock,  with medium to
r.apid internal  drainage.

     Soils of the bottom lands-The soils of the bottom lands are the Banks,
Laurel,  and Sarpy.   They  are on floodplains of various widths that have develop-
ed along practically all  of the creeks and rivers.   Many mine lease sites have
creeks or rivers  which transect them,  giving rise to soils of these types on
their properties.

     The Banks and Sarpy  soils have rapid internal  drainage,  but the Banks is
calcareous  whereas the Sarpy is not.   The Laurel  soil  is medium textured,
light grayish brown,  friable,  and calcareous.
                                     101

-------
 Salinity  and Alkalinity in Soils-

      Many soils  in  the western United States are affected by excessive con-
 centrations of either soluble salts or exchangeable sodium, or both, resulting
 in  reduced crop  production.

      The  term "saline soil"  is defined as a nonsodic soil containing soluble
 salts in  such quantities  that they interfere with growth of most plants.  The
 exchangeable sodium percentage (ESP) is less than 15 and the electrical con-
 ductivity of the saturated soil paste extract (ECe) is greater than 4 mmhos/
 cm.   The  term "sodic soil" (formerly called "alkali soil") refers to a condi-
 tion in which the soil contains sufficient exchangeable sodium to interfere
 with the  growth  of most crop plants, either with or without appreciable quan-
 tities of soluble salts.  Another condition which commonly occurs in semiarid
 and arid  regions is known as a "non-saline-sodic soil."  This type of soil
 contains  sufficient exchangeable sodium to interfere with the growth of most
 crops and does not contain appreciable quantities of soluble salt.  The ESP
 is  greater than  15 and the ECe is less than 4 mmhos/cm.  The pH usually is
 greater than 8.5 (Fuller  and Halderman, 1975).

      Rhoades  (1974) has  indicated that the primary sources of soluble salts in
 agricultural  soils are:   (1) irrigation waters, (2) salt deposits present in
 soil parent materials,  (3) agricultural drainage waters  (both surface and sub-
 surface)  drainage from upper-lying lands, and (4) shallow water tables.
 Rhoades (1974) has listed additional sources of soluble  salts, termed "second-
 ary" which include:  (5)  fertilizers, agricultural amendments, or livestock
 and poultry manures applied  to soils, (6) weathering soil minerals, and (7)
 rain and  snow.

      Undoubtedly, several of these sources have contributed to the formation
 of  saline and sodic soils in Campbell County in the past, and will contribute
 to  salt accumulation in the  future once spoils have been reclaimed.

      Of primary  concern to a monitoring program is the pollution potential of
 these saline and sodic soils as a consequence of their disruption and place-
 ment in designated burial sites.  Because of the importance of these types of
 soil  material as a source of pollution, this section of  the report attempts
 to  characterize  the soils of Campbell County which exhibit saline and/or  sodic
 soil  conditions, based largely on information available  in the 1939 reconnais-
 sance soil  survey of Campbell County, and a meager amount of laboratory data.
 It  should be noted  that all  of the land mapped as a soil series and designated
 as  exhibiting saline and/or  sodic soil conditions, may not in fact possess
 these properties.   In many instances these phenomena are highly localized in
 various microenvironments, largely a function of position on the landscape,
 proximity to the water table, and the nature of the parent material.

     Arvada series-Saline drainage water  accumulates  on  this  soil,  and on its
evaporation, a sodic salt deposit results.  This soil possesses a compact
claypan-like subsoil which causes poor drainage by impeding the downward
movement of water  and  thus  contributing to the salinization and alkalization
of the soil.  Calcium carbonate is present in the subsoil in streaks and


                                     102

-------
seams which occur below an average depth of 15 inches.  In some areas of the
County, wind erosion has removed the surface soil and exposed the heavy,
saline clay subsoil, resulting in scabby spots, barren of vegetation or marked
by the presence of salt-tolerant plants such as greasewood and saltgrass.

     This soil occupies extensive areas throughout the County and occurs on
all coal leases and, therefore, is considered a likely candidate for burial
in reclamation operations.

     Bridgeport series-This  soil  is calcareous at or  near the surface down-
ward, but has no horizon of calcium carbonate accumulation.   Some sodic salts,
seldom concentrated enough to injure vegetation,  are present in nearly all
areas where this soil has been mapped, with the areas most strongly affected
occuring along Wildcat Creek.  Due to the small  total  area that this soil
series occupies, it is not considered a potential source of pollution.

     Laurel series-The  soil  of  the Laurel  series has  developed from calcar-
eous recent alluvium washed from the soils of the sandstone, shale, and lime-
stone uplands, therefore, it has accumulated soluble salts.

     The lower parts of the subsoil  and substratum are splotched and streaked
with white accumulations of calcium carbonate and other salts to a depth of 5
feet or more.  This soil is not extensive in the  County, and occurs mainly
along the Belle Fourche River and South Fork Wildcat,  Horse, and Bitter Creeks,
with small areas along many of the small drains.

     Manvel series-Many small areas of  soil  included  with this soil type
contain free salts.  The so-called "white salts," chlorides, and sulfates,  are
most common, especially in the surface horizon;  but sodium carbonate,  or
"black alkali," occurs in small  quantities in the subsoil  and substrata.

     McKenzie series—This soil  varies widely in  stage of development, as is
indicated by its layers of calcium carbonate accumulation.   In some places
this carbonate-bearing layer is within a few inches of the surface; in others
it may be at depths as great as 3 feet.  This soil  occupies playas or
depressions in the central and south-central parts of the County and,
therefore, has been mapped on several  lease sites.

     Orman series-The surface soil of this  series is  commonly leached free of
salts, but they have accumulated in  numerous flat or slightly depressed spots
in quantities sufficient to injure certain types  of vegetation or prevent
their growth.  Some crystalline gypsum and other  salts are present in the sub-
soil  in most areas.

     Because only a few small areas  of Orman clay are mapped in the County, it
is not considered a significant pollution source.

     Pierre clay-The surface horizon of this soil is  noncalcareous, with the
subsoil  being a compact cloddy clay  in which some white streaks of calcium
carbonate have accumulated.   Some of the shale contains little calcium carbon-
ate,  and the soil  developed from it  is noncalcareous or only slightly cal-
careous.   Gypsum is usually present  in varying quantities in the lower part


                                     103

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of the subsoil and in the substratum.

     Renohill series-The upper subsoil of this series typically contains no
free calcium carbonate, but the lower  subsoil  is  more friable  and  has  an
abundance of calcium carbonate.

     Dim series-Calcium carbonate has accumulated in the lower subsoil of
this series but, because they have adequate  drainage  and excellent tilth,
they are considered some of the most productive soils of the uplands.
     p

Hydrologic Soil Classification

     Soil properties influence the process of  generation of runoff from  rain-
fall.  Runoff from a plot on a small natural watershed occurs  when the rate
of rainfall exceeds the infiltration capacity.  Kohnke (1968)  has  indicated
that the actual relationship of these  three  hydrologic factors is  complicated
by interception storage, depression  storage, and  surface detention of  the
water and that, if considered over longer periods, evaporation and transpira-
tion as well  as condensation and  adsorption  must  also be considered.

     Although such a complex analysis  of surface  runoff  is not warranted at
this time, an attempt has been made to at least provide  general  insight  into
this parameter, by delimiting areas of soil  on particular watersheds  that
exhibit similar infiltration characteristics.

     This task was accomplished by first defining a watershed  which encom-
passes (all or in part) the coal  leases to  be  monitored. The  defined  water-
sheds were then superimposed on soil maps corresponding  to the same areas of
interest, thereby yielding a soils map of the  watershed. Once this was  accom-
plished, the soils occupying a given watershed were classified in  hydrologic
soil groups as defined by Soil Conservation  Service  (SCS) soil scientists.
The hydrologic soil groups are as follows:

           •  (Low runoff potential).   Soils having high infiltration
              rates even when thoroughly wetted and consisting chiefly
              of deep, well-to-excessively  drained sands or  gravels.
              These soils have a high  rate  of  water transmission.

           •  Soils having moderate infiltration  rates when  thoroughly
              wetted and consisting chiefly  of moderately deep-to-deep,
              moderately well-to-well-drained  soils with moderately
              fine to moderately coarse textures. These soils have a
              moderate rate of water transmission.

           •  Soils having slow infiltration rates when  thoroughly
              wetted and consisting chiefly  of soils  with a  layer  that
              impedes downward movement of water, or  soils with
              moderately fine to  fine  texture.  These soils  have a
              slow rate of water  transmission.

           •  (High runoff potential).   Soils  having  very slow infil-
              tration rates when  thoroughly  wetted and consisting'


                                   104

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          chiefly of clay soils with a high swelling potential,
          soils with a permanent high water table,  soils  with a
          clay pan or clay layer at or near the surface,  and
          shallow soils over nearly impervious material.   These
          soils have a very slow rate of water transmission.

     The hydrologic classification of soils occurring in  Campbell  County  was
derived from the SCS National  Engineering Handbook  (1971),  and is  presented
in Table 5-4.   Areal  extents of the four soil  groups were determined  for  each
of the five watersheds by placing a grid (or "dot counter")  over the  map,
determining the number of grid intersections falling on each group, and then
computing the particular group percentages of the entire  watershed.   These
percentages are listed in Table 5-5 and are considered to be approximate.


                TABLE 5-4.  HYDROLOGIC SOIL CLASSIFICATIONS

Soil series
Arvada
Banks
Bridgeport
Dillinger
Fort Collins
Goshen
Laurel
McKenzie
Manvel-Moline
Orman
Pierre
Renohill
Rough Broken Land
Sarpy
Searing
Terry
Ulm
Wibaux-Searing
Map symbol
Aa, Ab, Ac
Ba
Bb
Da
Fa, Fb
Ga, Gb
La
Mb
Ma
Oa
Pa
Ra, Rb, Re, Rd, Re
Rf, Rg, Rh
Sa
Sb
Ta, Tb
Ua, Ub, Uc, Ud, Ue
Wa
Hydrologic
soil classification
D
A
B
B
B
B
C
D
C
C
D
C
D
A
B
B
B
C
                                     105

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               TABLE 5-5.  APPROXIMATE AREAL PERCENTAGES OF
                           HYDROLOGIC SOIL GROUPS

Watershed

Belle Fourche River


Cabal lo Creek


Donkey Creek


Little Thunder Creek


Rawhide Creek

Areal
A -
B -
C -
D -
A -
B -
C -
D -
B -
C -
D -
B -
C -
D -
B -
C -
D -
percent
1.7
56.8
22.3
19.2
0.5
42.0
39.2
18.3
33.4
30.6
36.2
41.1
26.3
32.6
37.7
23.9
38.4

 GEOLOGY

 Regional  Geology

      The  study area is located along the eastern edge of the Powder River
 Basin, a  structural and topographic basin which is approximately 250 miles
 long  and  100 miles wide.  The basin is bounded by the Bighorn Mountains on
 the west, the Black Hills Uplift on the east, and a series of arches and
 uplifts to the south.  As shown in Figure 5-10, the basin extends north into
 Montana.  The thick assemblage of sedimentary rocks underlying the basin
 reaches nearly 12,000 feet in thickness.  Paleozoic sediments rest on crystal-
 line  Pre-Cambrian rocks.  Although there are at least six unconformities in
 the sequence, the Paleozoic assemblages are approximately 2,500 feet thick
 (U.S. Geological Survey, 1974a).  Most are either limey sandstones, sand-
 stones, or marine limestones.  These formations have outcrops in the Bighorn
 Mountains to the west.

     The Mesozoic accumulations in the Eastern Powder River Basin include
 shales and claystones which were deposited in the Upper Jurassic and Creta-
ceous periods.  Thin conglomerate sequences and one thin limestone unit are
also present.  The Mesozoic sequence is about 7,000 feet thick in the study
area.
                                    106

-------
        ^
         BIGHORN
         —vs—
         UPLIFT  •. .
         •\  \ \ \OSHERIDAN
                              EXPLANATION
                                                O BELLEFOURCHE

                                                *'',..
     GILLETTE \  HILLS
               UPLIFT
         WIND RIVER BASIN\V^ _

          '•   *'  ""''•, ^V^V
          SWEETWATER  '"''.    ^>
•f       A*   **'
 'fi.t     . »i*    »
  '••-".IMH11    .»•

     HARTVILLE   .

 LARAMIE   UPLIFTf( i   \\ \
               •  B^ L
                                                      'O
                                                      : RAPID CITY
                                                            SOUTH DAKOTA
                                                          . t 1 I I
                                                       ModifiMi front tlw Ttctooic MAP
                                                          of the Unittd Statn.
        Figure 5-10.  Generalized map showing  the Powder River Basin
                      in relation to nearby  structural  features.


      This  study is primarily concerned with Cenozoic deposits.  Tertiary
 deposits are the most important in that they  contain the coal formations and
 that they  outcrop in the study area.  In  the  study area, the Tertiary deposits
 are  approximately 2,500 feet thick, and consist of siltstones, claystones,
 coal  beds, and discontinuous sandstones.  Quaternary deposits consist of allu-
 vium and colluviurn which occur in local drainage areas.

      The two formations of particular importance to this study are the Wasatch
 and  Fort Union.

      An angular  unconformity exists between these formations in the study
 area.  This  is probably indicative of a^large surge of Laramide uplift.  The
 lower Wasatch  is composed of arkosic sands  which were  probably derived from
 uplifted Pre-Cambfian strata (Davis, 1976).   The study area is approximately
 75 miles from  the Bighorn range and most  of the Wasatch rocks outcropping out
 in the area  are  sandy shales and shales.  Local  lenticular sandstone units
 found in the area are indicative of paleo-stream channels.  Small swamps
 existed during the Eocene period in this  area,  and some thin to moderately
 thick coal beds  exist in the Wasatch.   These  coals, with the exception of the
 Felix coal, are  not as  continuous as the  Fort Union coals.  The Wasatch For-
mation crops out in the western part of the study area.  The Fort Union
                                     107

-------
outcrops in the eastern part of the area, and it is in this area that the
major coal stripping operations are taking place.

     The Fort Union Formation is comprised of three members:  the Tullock,
the Lebo Shale, and the Tongue River.  The Tullock member is predominately
composed of shales and claystones with a few thin  discontinuous coal  beds in
its upper part.  These fine-grained rocks were derived from the uplifted
margins of the Powder River Basin after the gentle Laramide Orogeny of late
Cretaceous age.  The Lebo Shale member is characterized by a thick mudstone
assemblage which was probably associated with a surge in uplift of the
Bighorns.  Again there are a few thin, discontinuous coal  beds in this member.
The Tongue River member comprises more than half of the Fort Union Formation
(1,500 to 1,800 feet thick) and has the most persistent and thick coal seams
in the area (Glass, 1976).  The strata which separate the various coal beds
are shales and clays, although there are many discontinuous sandy areas
which indicate past drainages.  The Fort Union coals are shown in the fence
diagram presented as Figure 5-11.

     Geologic history contains numerous instances  where coal beds have burn-
ed.  When the coal outcrop is ignited, the burn proceeds downdip under the
overburden.  The overburden is subsequently "baked" and its geologic  charac-
ter is altered.  The new rock, called scoria or clinker, is usually reddish
orange and is quite resistant to weathering.  As a result,  many of the hills
in the area are capped by clinker zones.  Field observation shows that the
clinker reaches a considerable depth and eventually reaches a contact with
the coal seam.

Structure

     The Powder River Basin is an asymmetric,  gently sloping structural and
topographic depression in northeastern Wyoming.  In the study area, dips range
from three to five degrees to the west.  There are few faults or folds of any
significance in the area.  However, large scale compaction structures exist in
the northern part of the area.  These structures were discussed in a paper by
Law (1976).  As the coal beds are compacted by overburden, buried stream chan-
nel elastics experience less compaction and exist  as topographically high
areas.  Law (1976) shows that small normal faults  occur in these areas.

Geologic History

     The geologic history of the region was as follows:

           •  There was Paleozoic accumulation of  limestone, sandstone
              and shale in shallow seas as the basin was slowly down-
              warped.

           •  Transgression of the sea during the  Mesozoic allowed the
              deposition of thick shales.  Various transgressions and
              regressions are evident from limestone and conglomeratic
              phases.
                                     108

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                                                                                     LITTLC POWMR
                                                                                     •IVU COAL
                                                                                            Marl
                                          PUMPKIN IUTTI1 "e"«
                                            COAL FIELD
                                                             COMPILED  »NO MODIFIED FMOU
                                                             PUBLISHED REPORTI AND OPEO-
                                                             FILE REPORTS OF THE U.I.

                                                             SEOL06ICAL SURVEY
Figure 5-11.
Correlation of coal beds in the  Powder River  Coal  Basin
(Glass,  1976).
                                     109

-------
            •  The  Laramide  Orogeny shaped the current Powder River
               Basin

            •  During  the Orogeny, Paleocene swamps occupied the basin,
               and  thick accumulations of coal developed in the Tongue
               River Member  of the Fort Union Formation.

            •  Wasatch Formation elastics originated in areas uplifted by
               the  final Laramide activity.  A few thin coal beds occur
               in this formation.

            •  The  Oligocene White River Formation contained terrestrial
               elastics which have been eroded in the study area.

            •  Recent  conditions have shaped the surface topography and
               have allowed  the deposition of alluvium in surface drainage
               areas.

 HYDROGEOLOGY

      The  hydrogeology of the project study area is complex and subject to many
 local  variations.  For this reason, a general overview of the hydrogeology is
 presented first, followed by a mine-by-mine, site-specific discussion.  The
 data  and  information  presented here are a summary of published records sub-
 mitted to Federal  agencies  by the mining companies, supplemented with some
 field observations.   The quality of this report, therefore, is limited to the
 quality of information released by the mines.  Up-to-date hydrogeologic infor-
 mation must be made available for TEMPO to evaluate pollutant relationships
 with  local  hydrogeology.

 Shallow Aquifers

      Five different types of shallow aquifers exist in the study area:  alluvial,
 Wasatch Formation, scoria,  coal seam, and the Fort Union aquifers below the coal
 seams.  Their  relationships are fairly complex, as shown in Figure 5-12.

 Alluvial  Aquifers-

     Alluvial  material is found in stream drainages throughout the study area.
 Most of the  unconsolidated  alluviums are fine grained, subangular sediments
 which  have  been derived from Wasatch or Fort Union shales and sandstones.  Some
 larger  clasts  of locally derived clinker detritus may be present.  Alluvial
 transmissivities may  range  around 500 gpd/ft (Davis, 1976) but they have not
 been extensively tested.  The units seldom exceed 50 feet of thickness and
 storage coefficients  are probably 10~2 to 10~1.

     The alluvial aquifers  can have recharge-discharge relationships with every
other type of  aquifer in the area.  The interaction of surface water and ground-
water systems  in the  alluvium is very important, but is not well  understood.
                                     110

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                                                                        £;WASATCH

RECHARGE-OISCHARGE
POINTS

POSSIBLE EXCHANGE AREAS
     Figure  5-12.  Aquifer relationships (modified  from Davis, 1976)

-------
      Surface  runoff  associated with  precipitation recharges the alluvium and  it
 may be  transmitted to  the coal aquifers, or  it may move downgradient in the
 stream  channel  and eventually be evaporated.  During dry periods, the alluvial
 aquifers  are  probably  recharged from the beds which overlie the coal.  This
 water seldom  appears as  base flow  in the stream, as it probably moves down the
 streambed as  underflow.  Much of the water in the alluvium is discharged by
 evaporation.  Mater  budget studies should be used to try to quantify the volume
 of  water  which  is lost through this  process, although such a study would have to
 quantify  all  of the  inflows to and outflows from the other aquifer systems.
 This might prove to  be a very difficult process.  Well yields from alluvial
 aquifers  vary greatly  due to local differences in permeability and aquifer thick-
 ness, and there are  relatively few wells in the alluvial systems.

 Wasatch Formation Aquifers -

      These units are quite variable,  and can be good to very poor aquifers.
 There are many  paleochannels where relatively permeable sandstones transmit
 enough  water  for successful water wells.  Elsewhere, numerous clay layers can
 effectively perch water.  These layers make it very difficult to describe re-
 gional  aquifer  characteristics.  Also, numerous thin coal beds are located in
 the Wasatch formation.   The thickness of the Wasatch formation ranges from near
 zero in the coal outcrop regions to  approximately 300 feet at the western edge
 of  the  study  area.

      Although the units  dip to the west, local topography exerts a large influ-
 ence on  groundwater flow directions.  Approximately 1 to 5 percent of annual
 rainfall  is estimated  to reach Wasatch groundwater systems.  This water gen-
 erally  moves  according to gradients  which lead to local drainages.  Numerous
 small stock wells have openings in these strata, and most water level maps of
 the area  reflect the effects of gradients established by local drainages.  In
 addition  to rainfall infiltration, the units may be recharged by water in al-
 luvial  channels in the western part  of the study area, and by water transmitted
 through clinker-overburden contacts.  Natural discharge occurs in the alluvial
 valleys in the  eastern part of the study area and downward leakage accounts for
 the remainder of the natural discharge.  Most wells in the Wasatch are low
 yield stock wells, but wells which penetrate sandstone strata might produce up
 to  100  gpm.   The percentage of the total discharge attributable to extraction
 from wells  is not known, although it might be significant.

 Scoria  Aquifers -

      The  scoria  (clinker) areas are  probably the most interesting hydrogeologic
 phenomena  in  the study area.  When shales which overlie coal beds are baked,  a
 scoria-type rock is  formed.  These expanded rock masses can collapse into the
 void  left by  the burned coal.  Also, gases produced during the burn will rise,
 and  some of the  scoria are vesicular.  The result of these combined effects
can  be a very permeable aquifer.  Coal outcrop fires were quite extensive  in
the  past,  and the clinker zones in the study area are fairly continuous and may
extend  laterally underground for as  much as a mile (U.S. Geological Survey,
 1974a).   Transmissivities can range  from 102 to 106 gpd/ft  (Davis, 1976),  and
there is evidence to support values  near the upper end of the range.  A Wyoming
Highway Department pumping test referred to in Rahn (1976) reported specific


                                       112

-------
 capacities of 18 gpm/ft.   Other estimates of clinker transmissivity (Dr. J.
 Harshbarger, University of Arizona, oral communication, 1977) are on the
 order of at least 106 gpd/ft.   Storage coefficients generally reflect uncon-
 fined conditions and probably range around 10-1.

     The recharge-discharge relationships of the scoria aquifers are not well
 understood.  Although they have extensive outcrop areas, many areas may have
 developed  soil horizons with large  clay  fractions and poor infiltration poten-
 tial.  The fact  that most of the areas are hilly would  indicate fairly rapid
 runoff of  surface water, also lowering infiltration potential.  However, some
 scoria areas intersect alluvial valleys.  These are probably  recharge areas.
 The water-bearing characteristics of the clinker areas  indicate that they do
 receive substantial recharge, and the exact mechanisms  should be closely stud-
 fed in the future.  Scoria discharge areas depend upon  the local arrangement of
 the system.  The coal seams probably receive some amount of clinker discharge.
 In areas where alluvium is intercepted,  the recharge-discharge relationship de-
 pends on the head relationships of  the two systems.  When the clinker has more
 head, it will discharge into the alluvium, and the water may  eventually evapo-
 rate.  The converse situation would exist when the alluvium has more head than
 the clinker.  Minor amounts of scoria discharge may leak into the lower members
 of the Fort Union Formation.  Discharge  related to human activity is relatively
 small.  In areas where the clinkers are  mined for use as road paving materials,
 there is loss of water from storage.  Due to the hard rock character of the
 clinker, very few wells withdraw water from the scoria  aquifers.

 Coal Seam  Aquifers —

     The regional environmental impact statement (U.S.  Geological Survey,
 1974c) emphasizes the point that the coal seams are the best  aquifers in the
 area.  The reason for this observation is that the coals are  by far the most
 regionally extensive sedimentary layers  in the basin.   The permeability of  the
 coal is due to extensive fractures,  Transmissivities range from 102 to 104
 gpd/ft, and are  related to the thickness of the coal seam and the extent of
 local fracturing.  Wells in the coal seams seldom yield more  than 20 gpm, and
 most of them range around 10 gpm.   Transmissivities and storage coefficients
 for the coal aquifers vary widely,  depending on the nature and occurrence of
 the fractures in the coal.

     The coal seams are near the surface in the eastern part  of the study area.
•Most of the actual outcrop areas have been burned, so clinker zones line the
 outcrop pattern.  These are recharge areas for the coal seam  aquifers.  The
 clinker beds are quite permeable, and they may act as "head tanks" above the
 coals.  Also, the coal seams may receive recharge as downward leakage from
 overlying  Wasatch strata.  These overlying beds are relatively impermeable  and
 they act as leaky aquitards.  The local  occurrence of sandy zones in the over-
 burden makes it difficult to discuss regional aquitard  characteristics.  The
 coals are  also recharged in drainage areas.  In the study area, coal seams
 often lie  directly beneath alluvium, and they generally dip away from the
 drainage (see Figure 5-12).  The alluvium receives water from surface events
 and from local groundwater discharge of  the Wasatch beds.  The alluvial stream
 beds are probably very important interchange areas in the groundwater system
 in the Eastern Powder River Basin.

                                     113

-------
      Natural  discharge areas are less obvious than recharge areas.  Depth to
 the coals increases  as they dip to the west.  Some water is lost as downward
 leakage to the  lower members of the Fort Union Formation.  Most of the water
 in the coal  seam  generally moves westward under a small gradient under con-
 fined or semiconfined conditions.  Water wells account for most of the
 discharge from  the coal  seam aquifers.  Although the overlying sediments may be
 just as permeable as the coal in some areas (Rahn, 1976), most wells have been
 completed in the  coals because of their local reputation as water-bearing zones.
 The majority of water wells in the study area are small stock watering wells
 which are pumped  with windmills.  There are also a number of domestic wells.
 Seepage from the  coal seams will occur when they are mined.  As a rule of thumb,
 most companies  predict that they will have to pump about 70,000 to 120,000 gpd
 from their pits.

 Fort Union Aquifers  Below the Coal Seams —

      Groundwater  occurs  at various depths below the Wyodak-Anderson coal seams.
 Strata immediately beneath the coal seams are predominantly clay-rich, and
 these units can confine  deeper Fort Union water.  Most of the mines claim that
 little or no upward  leakage is expected to enter the mine pit through these
 confining layers. At greater depths, however, aquifers containing relatively
 good quality water exist.  The City of Gillette has many "soft water" wells
 completed approximately  600 feet below the base of the coal seam.  Transmis-
 sivities are on the  order of 104 gpd/ft, and storage coefficients reflect con-
 fined conditions. All of the mines are completing their supply wells in these
 deeper Fort Union aquifers.

      These aquifers  may  receive downward leakage from overlying strata, but
 their predominant source of recharge is from their outcrop areas to the east.
 Discharges from the  aquifers include pumpage, and upward or downward leakage to
 adjacent aquifers.

 Site Specific Hydrogeology

      Hydrogeologic descriptions of each of the seven mines in the project area
 follow.

 AMAX Belle Ayr  South-

      The  Belle  Ayr South mine is located approximately 20 miles south of Gil-
 lette.  The mine  began producing coal in 1975.  Hydrogeologic changes at this
 mine may  be  indicative of similar changes to watch for at the other mines in
 the  area.

      Wasatch overburden  in the vicinity of the Belle Ayr South mine is  selec-
 tively saturated  with groundwater.  Wet areas are characterized by sandstone
 lithologies, while the dry areas are shales or siltstones.  The Wasatch Forma-
 tion  thickens to  the west of the present pit, and it is anticipated that more
 saturated sandstone paleochannels will be encountered as mining continues.
 Pump test data  for Wasatch wells are shown in Table 5-6 and Figure 5-13.  The
 low transmissivities and semiconfined storage coefficients are similar  to the
results of other  pump tests in Wasatch wells.


                                      114

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                        TABLE 5-6.  AQUIFER  PARAMETERS  IN  THE  BELLE  AYR MINE  VICINITY
                                    (AMAX Coal Co.,  1977)
err
Well No.
N-l
M-3
N-5
N-6
N-9
N-ll
N-13
N-14
481
WRRI-7A
WRRI-10

Aquifer
compl eted
Wyodak
Wyodak
Uasatch
Wyodak
Open hole
through
Wyodak
(uncased)
Uasatch
Uasatch
Open hole
through
Uyodak
(uncased)
Uyodak
Fort Union
Uyodak
Average values
Azimuth
to observation
well
-
N-S
E-U
-

-
N-S

-
E-U
E-U
-
Pump test
Transmlssivity
(gpd/ft)

1353
6175
-

-
3495
™
-
1528
3542
3218
results
Storage
coefficients
.
0.01
0.0018
-

-
0.0054
'
-
0.0022
0.0038
0.0046
Transmissivity
(gpd/ft)
recharge (in/yr)
524
9894
187
2755
1140
1959
2368
4133
1677
488
-
2512
Calculated Aquifer
recharge Calculated thickness
(in/yr) porosity (ft)
0.12 65
0.14 NA 62
33.0 0.04 100
65
95?
50
1.48 - 54
80
0.13 60
3.13 0.12 60
90
-

-------
en
        1.0
     U)
        0. I
IO
  '3
           LEGEND
        A  WRRI-7A
        •  N-5
        x  WRRI - 10
        +  N-I3A
          RECOVERY DATA
             CIRCLED

                  T
               WRRI -7A
                MATCH
                POINT
                                  ©
                            0
          ©    ©
          -WRRI-10
           MATCH
           POINT

              ®  X
                             N-5-MATCH
                               POINT
                                  ®x
                                           ©
                                         e +
                                                -+- N-I3A
                                                 1  MATCH
                                                   POINT
                                                              ©
                                                                 e.'
                                                       N-5
                                                      W(u)=l
                                                      l/u = IO
                                                                                 WRRI-  WRRI
                                                                         N-I3A    10      7A
                                                                                  rs=3.5
                 t  /min
                         ^-2
1-1
                                              10
          Figure 5-13.   Plots of results  from four pump tests  near Belle Ayr Mine (AMAX Coal  Co.,  1977)

-------
     Scoria aquifers are locally significant at this mine.  Initial cuts into
scoria hills for road gravel encountered water and some water is still being
pumped from these areas.  AMAX is trying to determine the source of this
water in order to evaluate the problem (Ted Terrell, AMAX Coal Co., person-
al communication, 1977).  As mining progresses to the west, no significant
scoria areas will be encountered and large inflows to the pit from clinkers
are not anticipated.

     Figure 5-14 is an isopach map of the alluviated areas along Caballo
Creek.  The alluvium is seldom thicker than 30 feet, with channel widths
ranging from 400 to 2,000 feet (AMAX Coal Co., 1977).  AMAX has not publish-
ed the results of any aquifer tests in the alluvium, except to say that such
tests show low permeabilities in the alluvium (AMAX Coal Co., 1977).

     The coal seams at Belle Ayr South are moist and some of the fractures
conduct significant groundwater flow.  Field observations note that at the
highwall some fractures discharged approximately 15 gpm.  AMAX estimates that
approximately 100,000 gpd is pumped from the mine (U.S. Geological Survey,
1975).  Coal transmissivities and storage coefficients are given in Table
5-6.  Such data are local, and will vary with the number of water-bearing
fractures which are penetrated.

     Well hydrographs for wells in the Wasatch Formation, the coals, and the
alluvium are shown in Figures 5-15 through 5-17.  Monitoring wells have been
installed by the Wyoming Water Resources Institute at the locations described
in Table 5-7.

AMAX Eagle Butte-

     The Eagle Butte Mine, located just south of the North Rawhide Mine, has a
hydrogeologic situation similar to that of the Rawhide Mine.  Groundwater oc-
curs above, below, and in the coal seams, as well as in the alluvial areas and
in clinker deposits.

     The Wasatch Formation contains some groundwater but cannot be thought of
as a regional aquifer.  Some overburden wells drilled on the lease, such as
wells D-534 and C-592, encountered no water in the Wasatch Formation (see Fig-
ures 5-18 and 5-19).  As shown on the geologic cross-sections, Figures 5-18
and 5-19, lithologies within the Wasatch Formation are discontinuous.  There-
fore, the aquifer parameters shown in Table 5-8 are probably not representative
of the entire Wasatch Formation.  Transmissivities listed for two pump tests
were 30 gpd/ft and 177 gpd/ft.  More tests are needed to verify these results.
Storage coefficients will most often reflect unconfined conditions, although
the 0.003 figure of Table 5-8 indicates some locally confined areas.

     Scoria'deposits are located at most of the topographically high areas on
the Eagle Butte lease area, and adjacent to the coal, as shown on Figures 5-18
and 5-19.  AMAX has not indicated the extent of their drilling program in
scoria, nor have they discussed the percentage of scoria areas which are wet
or dry.  The pump test on well GN-8, which penetrated a scoria zone, yielded
relatively high transmissivities (140,000 gpd/ft) as shown in Table 5-8.
Storage coefficients should reflect unconfined conditions.

                                    117

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00
                                                                                                          21  T47N
                                                                                           COAL TEST HOLE
                                                                                           ISOPACH OF UNCONSOLIDATED
                                                                                           DEPOSITS, DASHED WHERE
                                                                                           APPROXIMATED
                                                                                           STREAM
                                                                                           PROPERTY BOUNDARY
                                                                 105°22'30"
         Figure 5-14.   Isopach map of unconsolidated deposits along Caballo Creek  (AMAX Coal  Co., 1977).

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   0)
   Lu
   oe
  §
  is
  o
  _i
  LU
  CO
  a.
  LU
  O
       10
       15
  y   30
35
       45
       115
      120
      125
1974
                                      WRRI-12 UNCONSOLIDATED DEPOSITS
                                       N-5 WASATCH AND COAL
                                       N-l COAL
                          1975
                                                 1976
Figure 5-15.   Hydrographs  of three wells  (AMAX Coal Co.,  1977),


                                119

-------
po
o
u.
QC

t/>
Q
Z

O

-------
       116.5
       116.6
     *>

     £116.7
       116.8
     ff>
     O
       116.9
     O
     oc
     O

     § 117.0
ro


     a.
     ui
     Q
     _i
     ui
     oc
     LU
117.1
       117.2
       117.3
       117.4
       117.5
              I  I I  I  I  I I I I I  I I  I  I  I  I I  I  I  I  I  I  I  I  I  I  I  I I I I  I  I  I  I  I  I  I  I  I  I  I  I  I  I  I I I I I  I  I I  I  I
            10
               15
 20

MAY
15
31 1
10
 15

JUNE
20
25
30 1     4

   JULY
          Figure 5-17.   Water level  fluctuations in well  481, May 10 - July 4, 1974  (AMAX Coal  Co., 1977).

-------
ro
ro
                           TABLE 5-7.  WELL COMPLETION DATA, WRRI GROUNDWATER OBSERVATION
                                        WELLS,  AMAX BELLE AYR SOUTH  (AMAX Coal Co., 1977)
Well No.
WRRI-2


WRRI-3

WRRI-5

WRRI -5- A

WRRI-7


WRRI-7-A

WRRI-8

Location
SE>s,SE%,NW»s
Sec! 35*
T48N.R71W
Sec! 27*
T48N.R71W
Sec! 34
T48N.R71W
Sec! 34*
T48N.R71W
NW%,SWJj,SW»i
Sec! 27*
T48N.R71W
NW%,SWJs,SW>s
Sec. 27
T48N.R71W
Sec! 33*
T48N.R71W
Initial
Total Perforated Depth to water
depth depths coal level
Formation (feet) (feet) (feet) (ft.bl.g.s.)
Cast 36 30-36 NA 30
overburden

Wyodak 206 166-206 166 186
seam

Wyodak 135 75-135 70 76
seam
r
Wyodak 135 75-35 70 76
seam

Fort Union 329 257-329 170 245


Fort Union 329 257-329 170 245

Alluvium 20 NA NA 9

Present
water
level
(ft.bl.g.s.) Remarks
18 Located ^60' N of
stream south of mine

NA Plugged off at 122'

NA Plugged off at 70'
with bentonite mud

76 Located =20' S of
WRRI-5, SEAM project

108 Coal 1s cased off.


107 Located 35' W of
WRRI-7

9 75' N of bridge abut-
ments. SEAM project

WRRI-9   Stfc.NE^.NE*
         Sec. 35
         T48N.R71W
Alluvium      18
                                                  NA
NA
-20'  E of ponded
Caballo Creek.  SEAM
project
                                                                                                         (continued)

-------
                                              TABLE  5-7  (continued)
ro
oo
Well No.
WRRI-10
WRRI-10-A
WRRI-11
WRRI-12
N-l
N-3
N-3-A
N-5-A
Total Perforated Depth to
depth depths coal
Location Formation (feet) (feet) (feet)
NE%,NE>$,SW>i Wyodak 281 188-281 188
Sec. 31 seam
T48N.R71W
NEH.NEJs, SW% Wyodak 281 200-281 188
Sec. 31 seam
T48N.R71W
NESs,NE»i,SWJs Wasatch 194 90-124 NA
Sec. 31 174-194
T48N.R71W
NE%,NE»i,SW»4 AlluviUm 20 0-20 NA
Sec. 31
T48N.R71W
SWINE'S, SW% Wyodak 190 130-190 130
Sec. 27 seam
T48N.R71W
SW^,NW»s,NWJs Wyodak 122 50-122 44
Sec. 3 seam
T47N.R71W
SWs,NWs,NW% Wyodak 110 50-110 46
Sec. 3 seam
T47N.R71W
SE%, SE>sSE% Wasatch 135 40-135 NA
Sec. 28
T48N.R71W
Initial Present
water water
level level
(ft.bl.g.s.) (ft.bl.g.s.) Remarks
30.2 30.2 Located 47
WRRI-12
30.2 30.2 Located 47
WRRI-12
6.8 6.8 Located 66
WRRI-10
9 9 Located 60
streamgage
project
168 119 Core hole
reamed out
85 69 Core hole
85 69 Located 38
1 N of
1 N of
1 N of
' NW of
. SEAM
that was
and cased

1 of N-3
40 41 Offset of core hole
                                                                                                  (continued)

-------
                                               TABLE 5-7 (continued)
no
Well No. Location
N-5-B SE%, SENSE'S
Sec. 28
T48N.R71W
N-6 SEJj.SEJs.SEJg
Sec. 33
T48N.R71W
N-ll SWSj.NWJs.NWsj
Sec. 28
T48N.R71W
N-13 SEJ" SW'' SE5-
Sec! 29*
T48N.R71W
N-13-A SE5s,SW>s,SEJs
Sec. 29
T48N.R71W
481 SWs SE% SEk
Sec! 27*
T48N.R71W
* 	 	 •
Formation
i Wasatch
; Wyodak
seam
i Wasatch
: Wasatch
Wasatch
Wyodak
seam
— '
Total
depth
(feet)
135
140
207
190
190
160
-- .-.-.-
Perforated
depths
(feet)
40-135
75-140
140-200
80-170
80-170
100-160
Depth to
coal
(feet)
NA
70
207
190
190
95
Initial
water
level
(ft.bl.g.s.)
40
93
NA
NA
NA
110
Present
water
level
(ft.bl.g.s.)
41
37
85
60.5
60
118
Remarks
Located 50' W of
N-5-A
Core hole.
SEAM project
Offset of core hole.
SEAM project
Offset of core hole.
SEAM project
Located 28.5' N of
N-l. SEAM project
Core hole

-------
                  4500-
en
              'r-   4400
              co

              E


              OJ


              O
                  4300-
              2   4200
              UJ
                  4100-
                  4000-
                             NORTH
                             O
                             (0
                              I

                             O

                              I
                                                       BROADUS HIGHWAY
                                                                                      SOUTH
o>
m
m

o
 l
                              ro
                              «n
                              1
                              o
                              1
0
in
 i
o
 i
ro

 i
O
 I
                                                                              o>
o
 1
00
fO
 1

Q

 1
in
ro
 i
a
 i
                                                                                 Sh
    Figure 5-18.
Geologic cross section from the center of the east line, section 22, to the NE corner,

SE%, NE%, section 27, T51N, R72W.  Well numbers are indicated across top.  Dotted

unit in hole D-459C is same scoria encountered in nearby well GN-8.  Static water

level is marked by dotted line between inverted triangles (AMAX Coal Co., 1977a).

-------
                                 NORTH
                                                                           SOUTH
                     
-------
                          TABLE 5-8.   SUMMARY OF AQUIFER TEST DATA (AMAX Coal  Co.,  1977a)
ro
Test
well
No.
BAN-1A

BAN- 3
BAN- 4
BAN- 5
GN-6
GN-7

GN-8
GN-9
D-305

Date
of
test
12-23-75
12-12-75
8-18-75
8-18-75
8-18-75
23-28-75
1-6-76
1-6-76
1-7-76
1-7-76
6-27-74
6-27-74
Type
test
Sp. Cap.
Pump
Sp. Cap.
Sp. Cap.
Sp. Cap.
Sp. Cap.
Sp. Cap
Pump
Sp. Cap.
Sp. Cap.
Sp. Cap.
Pump
. Length
Observ . of
well test
No. (hrs.)
3.42
BAN-1 3.42
0.50
0.88
0.82
0.35
4.63
GN-7B 4.63
0.78
0.33
10.25
D-305A 10.25
Prod.
rate
(gpm)
0.63
-
7.5
7.2
3.5
0.8
2.1
-
13
0.05
1.6
-
Final
draw-
down
(ft)
27.0
0.50
28.9
57.9
3.2
29.2
11.1
0.27
0.1
30
-
0.56
Spec.
cap.
(gpm/ft)
0.02
-
0.26
0.12
1.1
0.027
0.19
-
130
0.002
-
-
Geol.
fm.
Was.
Was.
Coal
Coal
Coal
Coal
Coal
Coal
Coal & Burn
FU
-
-
Trans,
(gpd/ft)
30
177
240
130
1200
20
300
676
140,000
5
-
1280
Aquif.
Thick.
(ft)
30
30
101
100 ?
100 ?
33
140
140
58
40
113
113
Perm.
(gpd/ft2)
1
5.9
2.4
1.3
12
0.61
2.1
4.8
2400
0.125
-
11
Storage
coeff. Comments
-
0.003 r = 55'; Bound. Effects
-
-
-
-
-
0.0011 r * 124'; Leaky Aquifer
-
- Pumped by air jet
-
0.0022 r = 38.5

-------
     The major occurrence of alluvium on the lease is in the channel  of Little
Rawhide Creek.  The streambed alluvium trends north through the lease area.
There is also some alluvium in the Dry Fork Little Powder River streambed at
the extreme southeastern corner of the Eagle Butte mine.  The thickness of the
alluvium is probably not greater than 40 feet at any point on the lease (AMAX
Coal Co., 1977a).  No pump test data have been published by AMAX for the
alluvial areas.

     The coal seams on the Eagle Butte lease yield water to wells.  The coal
thins towards the north (Figures 5-18 and 5-19) and is generally 75 feet thick
throughout the lease area.  Permeability in the coal is secondary in that all
water flows through fractures.  AMAX has not indicated that fracture orienta-
tion or developments have been studied.  Hydraulic characteristics include
transmissivities ranging from 20 to 1,200 gpd/ft (Table 5-8), and semiconfined
storage coefficients (0.0011).

     The water levels in all formations on the Eagle Butte lease are relative-
ly  stable.  Annual fluctuations are generally less than 3 feet, as shown by
Table 5-9.  The well hydrographs (Figures 5-20 and 5-21) show that seasonal
variations are slight, and that premining water levels are fairly stable.

     The potentiometric surface in the Roland coal is continuous with the sur-
face shown at the  North Rawhide Mine.  A groundwater mound exists at the west
central edge  of  the lease,  indicating a possible recharge area or poorly con-
fined conditions.  The primary direction of groundwater flow on the lease is
northwest.

     AMAX  has published data on 30 monitor wells being used on the Eagle Butte
property.  Completion information can be found in Table 5-10.  The well  loca-
tions are  also given in the table.

ARCO Black Thunder -

     Fairly extensive groundwater investigations have been conducted on  the
Black Thunder lease by Atlantic Richfield and by the University of Wyoming.
These researchers  have paid considerable attention to the Roland  coal aquifer,
Wasatch aquifers,  and pre-Roland aquifers.  Scoria and alluvial aquifers are
relatively unstudied.

     Wasatch  aquifers on  the lease are local phenomena.  Lenticular  sandstones
transmit small amounts of water (usually less than 15 gpm) to  wells.   No pump
tests have been  run on Wasatch wells.  The Wasatch overburden  thickens  from
east to west  on  the mine  site, and where groundwater does exist,  such waters
are unconfined.

     Scoria units  exist to  the east of ARCO's proposed mine.   For this  reason,
minimal study of these clinker units has occurred.  ARCO notes that  such scoria
beds have high permeabilities, with water transmitting  capabilities  similar to
those of gravels.  Alluvium exists in the valleys of Little  Thunder  and North
Prong Creeks.  The alluvium has not been studied to any extent,  but  ARCO indi-
cates that lithologies include unconsolidated gravels,  sands,  and clays.
                                    128

-------
TABLE 5-9.  STATIC WATER LEVELS MEASURED ON UNINSTRUMENTED WELLS (AMAX  Coal  Co.,  1977a)
Static water levels (ft below casing top)
Well No.
BAN- 3
BAN- 4
BAN- 5
GN-6A
GN-6B
GN-6
GN-7
GN-7A
GN-7B
GN-7(OB)
GN-8
GN-9
GN-9A
GN-9(C)
GNH-1
GNH-3
GNH-4
GNH-5
GNH-6
GNH-10
GNY-11
GNH-12
0305A
AMAX #8
8/18/75
74.6
37.1
79.2
-
-
-
-
-
-
-
-
-
-
-
8.1
6.6
13.4
11.6
9.0
8.3
-
2.9
-
-
12/18/75 to
12/4/75 1/7/76 1/10/76
75.0 (Casing cut 1.5')-
29.0
79.0
Dry hole — not cased
-
25.8
7.0
10.1
6.9
7.3
63.4
72.3
11.3
28.0
9.5
8.6
15.4
13.3
9.7
8.9
9.7
4.1
-
- -
2/13/76 3/2/76
74.5
28.9
78.9
-
-
26.7
6.5
-
6.8
7.3
77.9
68.2
9.9
-
7.6
4.9
'11.6
11.3
6.5
8.5
10.7
4.1
79.0
13.1
3/31/76
78.8
28.7
-
-
-
26.4
6.1
7.0
6.7
-
63.9
63.3
9.9
-
6.7
4.3
9.8
9.7
6.6
11.9
10.5
3.9
-
20 ?
5/5/76
73.6
28.3
80.0
-
-
26.6
-
_
.
-
-
60.1
9.9
-
6.2
2.1
9.9
10.5
6.4
8.0
9.4
3.5
-
-
6/15/76
74.0
20.6
78.9
19.8
-
26.4
6.7
7.0
7.0
-
63.5
-
-
-
6.0
3.9
7.4
11.0
7.9
7.9
Casing
3.4
77.5
-
7/2/76
74.3
28.6
79.1
-
-
25.8
6.9
7.3
7.3
-
63.5
57.0
10.0
~
6.2
4.5
9.7
-
-
8.2
broken
4.9
78.6
-
8/1/76 9/1/76
-
29.3
79.2
20.1
-
24.8
7.6
7.9
5.8
-
64.9
54.6
9.7
-
8.6
7.5
Casing
12.5
9.4
8.9
-
Plugged
-
-
10/13/76
-
29.8
79.0
-
-
25.0
7.5
8.1
7.6
-
64.4
54.1
9.5
-
9.1
6.5
broken
12.4
9.8
9.0
10.0
-
-
-
11/1/76 12/2/76
75.8
29.9
79.1
-
-
25.5
7.2
7.8
7.2
-
63.5
56.6
-
-
6.7
4.1
-
13.8
13.2
12.5
-
-
-
-

-------
             4260
            4250
            4240
oo
o
                                        D-305

                                     D-376
            4210
           4200
                    i   i   i   i   i   i   i
 _    BAN-2
J	i*"T""i""" i"~i'
                    Q-'  K  >  o
                    UJ  O  O  LU
                    w  o  z  o
                       1974
      1975
1976
              Figure 5-20.  Monthly water  level elevations in  instrumented monitor wells.  The rise  in
                           water level  in D-376 during summer and fall of 1975  is probably due to a
                           change in monitoring personnel (AMAX Coal Co., 1977a).

-------
    4270
2   4260
    4250
                                       BAN-1

                              flARSHALL N0.1
                                  D-409


            I   I   I   I   I   I   I   I   I   I   I   I   I   I   I   1   I   I   I   I   I   I   I  I   I  i   i

            Si  h'  5i  M  z  pi  of  g:  >-  z  j d p: J; 5j cj  a: d  ge  of  >-  z  J  d  p:  K  >
               1974
1975
1976
      Figure 5-21.   Monthly water level elevations  in instrumented monitor wells.  The sharp drops
                    in water levels in D-409 during fall 1975 are probably due to a change in
                    monitoring personnel (AMAX Coal Co., 1977a).

-------
              TABLE  5-10.
MONITOR WELL INVENTORY FOR AMAX'S  EAGLE BUTTE MINE.  ELEVATION  SOURCES.ARE
LEVELINE  SURVEY (S), TOPOGRAPHIC MAPS  (T), AND COMBINATIONS OF  THE TWO (Tc)
(AMAX Coal  Co., 1977a)
oo
ro
Location
Well No.
BAN-1
BAN-1A
BAN- 2
BAN- 3
BAN- 4
BAN- 5
GN-6
GN-6A
GN-7
GN-7(OB)
GN-7A
GN-7B
GN-8
BN-9
GN-9(C)
\*> • J \ V* f
GN-9A
D-305
0-305 A
D-376
D-409A
GNH-1
GNH-3
GNU- 4
GNH-5
GNH-6
GNH-10
GNH-11
fiNH-1?
UI1M w i L,
Marshall #1
AMAX #8
Coordinates (ft)
1720 fel
1670 fel
2000 fnl
728 fnl
2770 fnl
1775 fnl
1290 fnl
20 fnl
1280 fsl
1280 fsl
1460 fsl
1660 fsl
1620 fsl
1620 fsl
1620-fsl
1620 fsl
2620 fsl
2581 fsl
680 fnl
Swenr
520 fsl
160 fsl
810 fsl
2340 fsl
2540 fsl
2830 fsl
1640 fsl
3120 fsl
2730 fsl
NW, NW,
, 150
, 160
, 2050
, 2160
, 1880
, 20
, 20
, 20
, 60
, 60
, 60
, 60
, 20
, 770
, 770
, 830
, 2210
, 2210
00

, 2650
, 2230
, 3020
, 2820
, 3530
, 2910
, 2890
, 2890
, 70
NW, NE
fnd
fnd
fel
fel
fwl
fwl
fwl
fwl
fwl
fwl
fwl
fwl
fwl
fel
fel
fel
fel
fel
fwl

fwl
fwl
fwl
fwl
fwl
fwl
fwl
fwl
fwl

Sec
22
22
26
16
16
16
21
21
21
21
21
21
23
28
28
28
27
27

23
16
16
16
16
16
16
16
16
27
28
T
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
BIN
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
51N
R
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
72W
Elevation
Ground
(ft.msl)
4349
4345
4336
4227.8
4202.8
4276.8
4290.6
_
4252.5
4252.5
4252.2
4252.1
4312.9
4279.3
4279.3
4277
4330.3
4328.8
4291.4
4319.5
4200.2
4202.7
4197.7
4187.9
4182.2
4182.81
4191.9
4177.0
4283.4
4275
Source
S
S
T
S
S
S
T
_
S
S
S
S
S
S
S
T
S
S
S
S
S
S
S
S
S
S
S
S
T
T
Casing
height
(ft)
0.7
1.5
1.0
1.6
2.1
0.8
3.0
0.0
1.4
1.3
0.6
1.3
1.4
2.0
2.2
2.1
l."5
1.4
0.7
0.4
0.8
1.0
3.5
1.1
3.2
1.1
3.5
1.7
0.0
1.9
Total
depth
(ft)
210
218
390
224
173
160
76
117
260
74
260
157
117
313
261
320
356
365
330
330
17
13
15
17
31
18
15
15
—
58
Casing
depth
(ft)
0-195
0-218
0-240
0-224
0-173
0-160
0-76
None
0-260
0-74
0-26
0-20
0-117
0-307
0-183
0-107
0-240
0-240
0-158
0-155.
17
12
14
15
14
12
11
llh

58
Cement
or
packer
depth
(ft)
Surf.
Surf.
240
82
54
123
42
_
76
_
76
—
60
263
None
57
240
240
158
155
None
None
None
None
None
None
None
—
—
30
Perf.
interval
(ft, depth)
95-195
118-218
Open hole
164-244
123-173
125-160
42-75
_
180-260
54-74
18-260
0-20
60-307
307-267
163-183
67-107
240-356
240-365
158-330
155-330
14-17
9-12
11-14
12-15
11-14
9-12
8-11
8%-llh
—
30-58
Formation
aWas.
Was.
Coal
Coal
Coal
Coal
Coal
_
Coal
bQal.
Coal
Qal.
Coal&Burn
CPU
Coal
Was.
Coal & FU
Coal & FU
Coal
Coal & FU
Qal.
Qal.
Qal.
Qal .
Qal .
Qal .
Qal.
Qal.

Coal
Logs
(X-same)
hole)
D482
D482.X
0339.X
X
X
H167
X
X
X
GN-7
GN-7
GN-7
D459C
X
GN-9
GN.-9
GN-9.X
D-305
X
X
X
X
X
X
X
X
X
X
5070
C421
Casing
desc.
4" PVC
4" PVC
4" PVC
4" PVC
4" PVC
4" PVC
5" PVC
None
5" PVC
1" Stl
5" PVC
5" PVC
5" PVC
5" PVC
1" Stl
5" PVC
5" PVC
5" PVC
5" PVC
5" PVC
IV Stl
iy sti
IV Stl
IV Stl
IV Stl
IV Stl
IV Stl
IV Stl
4" PVC
5" PVC
Date
drilled
6-18-74
6-20-74
6-21-74
9-75
9-75
9-75
12-75
12-75
12-75
12-75
12-75
12-75
12-75
12-75
12-75
12-75
6-22-74
6-24-74
6-25-74
6-21-74
9-75
9-75
9-75
9-75
9-75
9-75
9-75
9-75
1973(?)
1-76
       "Wasatch
        Quaternary Alluvium
       cFort Union

-------
     The pre-Roland aquifer is composed of fractured shales and other fine-
grained materials.  These materials have low permeabilities, but they are satu-
rated.  The University of Wyoming study indicates that the pre-Roland aquifer
is confined, but the nature and/or location of the confining layer is unclear.
It is assumed that the strata directly beneath the Roland seam must act as the
confining layer.  The University of Wyoming study indicates that some upward
leakage may occur through this confining layer.  As shown by Table 5-11, one
pump test in the pre-Roland material did not yield interpretable data.  A second
pump test did give a transmissivity value of 7,200 gpd/ft, indicating that the
pre-Roland material may be as permeable or more so than the Roland coal  itself.

     The Roland coal has been pump tested many times as indicated by Table 5-11.
Transmissivity values ranged from 32 to 25,000 gpd/ft, with an average value of
35,000 gpd/ft, and storage coefficients generally reflected confined conditions
or semiconfined conditions.  ARCO has indicated in its Mining Plan Update (1977)
that the coal is virtually full of water except for some areas in the eastern
part of the lease.  In these areas, water table or semiconfined conditions are
expected.  The Roland seam is approximately 70 feet thick over the lease area.

     The potentiometric surface map submitted by ARCO in its 1977 Mining Plan
Update shows levels monitored in 1974 (Figure 5-22).   Groundwater flow in the
Roland aquifer generally had a westward component, as supported by carbon-14
age information submitted by the University of Wyoming (Figure 5-23).  ARCO has
increased its number of monitoring wells since 1974 and, hopefully, is studying
interaquifer exchanges and potentiometric surface changes.  Figure 5-24 shows
monitor well locations.

Carter North Rawhide —

     The groundwater systems beneath Carter's Rawhide Mine lease are described
in the company's May 1977 Mining Plan Update.  Groundwater exists in the Wasatch
Formation, the scoria hills, the alluvium, the coal seams, and above and below
the coal seams as indicated by Table 5-12.

     Approximately 50 percent of the Wasatch overburden is composed of sand-
stones.  These sandstones are interbedded with the clays, shales, and silt-
stones which comprise the remainder of the Wasatch Formation.  The discontinuous
character of and the questionable hydraulic connections between the sandstone
units limit their performance as prolific water-bearing systems.  The Wasatch
•aquifers generally have an unconfined potentiometric surface, although local
shales or clays may confine the water for short distances.

     The scoria deposits at the Rawhide mine bear close inspection.  In  late
1976, a scoria hill  was breached during construction  excavation.   Carter had
to pump 6,000 gpm for several  days to dewater the hill.   Water levels were
measured frequently throughout this dewatering,  and the declines  were analyzed
to get an idea of the  hydraulic properties of the scoria.   Transmissivity
values on the order of 10& gpd/ft were calculated.   Not all  clinker (scoria)
deposits are saturated, however,  and additional  data  are required to adequate-
ly assess scoria  hydrogeology.
                                     133

-------
                       TABLE  5-11.
CO
CALCULATED VALUES OF TRANSMISSIVITY AND STORAGE  COEFFICIENT
IN ROLAND FORMATION (ARCO,  1977)
Pumped
Rl
R2
R2

R5
R5
R6
R7
R8

R9
R10A
RIGA
R12
R12A
R12B
PR12E

R17A
R151
R153
R154
Silo #2
Stuart
Ranch
" 	 • ' 1 	 - 	 Ill — nil —•nil-.
Obser-
vation Aquifer
_
—
R2A

—
R-5A
—
—
-

_
_
R10D
_
R12B
RI2C
—

R17
_
_
_
_

—
Roland
Roland
Roland

Rol and
Roland
Roland
Roland
Roland

Roland
Roland
Roland
Roland
Roland
Roland
Pre-
Roland
Roland
Roland
Roland
Roland
Pre
Roland
—
Test
method
Jacob9
Jacob
Leaky
aquifer
Jacob
The is-
Jacob
Jacob-
Jacob

Jacob
Jacob
Jacob
Jacob
Jacob
Theis
Data

Theis
Jacob
Jacob
Jacob
Jacob

Jacob
— 	 	 — ..-[. r.
Obser-
vation Flow
radious rate
(ft) (gpm)
—
—
93

_
93
—
—
—

_
_
60
_
24.
39.
too

100.
_
_
_
—

—
6.8
21.4
21.4

21.8
21.8
15.0
20.0
30.0

5.0
5.0
50.0
5.0
5 5.0
5 15.0
erratic to

0 12.0
23.2
6.0
4.0
50.0

50.0
•' '" • •"•• • 	 ..-nil.
Average
trans- Storage
missivity co-
(gpd/ft) efficient
4,600b
5,600b
3,400

3,800b
5,600
100C
3,800b
4,500b

1 ,300C
4,400b
25,000d
450b
750d
650
analyze

300
600b
32C
32 b
7,200b

790
Comments

— Data erratic; results questionable
_
4.4 x lO'4

*»
2.5 x 10-*
Data skewed
Leaky condition

_
Slightly skewed data





- Data skewed; results questionable
_
Data skewed at end

- ~Data erratic between drawdown and

_
^
7.0 x lO-3
_
2.0 x 10-3
1.5 x 10-6


6.0 x 10-4
_
_
_
-

—
recovery
Data erratic
Data skewed
Data slightly skewed
Data erratic
Data reasonable
Data did not fit curve well


Data fit Theis better than
Data erratic
Data skewed
Data somewhat erratic
Data skewed slightly

Data skewed









leaky






            a
             Jacob method works well only in homogeneous and isotropic artesian aquifers with a small radius and a  large
             time period (Walton, 1970).   May be a reason for skewed and erratic test  data and results.

            ^Average value between drawdown and recovery test analyses


            °Recovery test only analyzed

            dDrawdown test only analyzed

-------
             LEGEND

        MONITORING WELL WITH
        STATIC WATER LEVEL
6000 FEET
Figure 5-22.  Potentiometric surface map, ARCO Black Thunder Lease
              (ARCO, 1977).
                              135

-------
                      R 70 W
     R-2  (30,000 ± 2430)
     R-5  (24,220 ± 3400)
     R-7  (33,740 ±4100)
     R-IO (17,300 ± 580)
     R-ll (26,270 ± 1380)
     R-15 (14,330 ± 440)
SILO (PRE-(I 1,170 ± 430)
 ROLAND)
                                     (PRE-ROLAND)
      LEGEND
CARBON-14 AGE DATES (years)
                    8000 FEET
  Figure 5-23.  Groundwater flow in  Roland aquifer
               (University of Wyoming, 1976).
                       136

-------
       R,,WI   »R2       R3
           17            16
      (R)a commercial  well
                            R 7.0 W

                               W2
                                 BT-77
         LEGEND

•  MONITORED WELLS ON SITE

A  STOCK WATER WELLS

   CONTINUOUS RECORDER ON
   ROLAND FORMATION WELL
                                                          SOOO FEET
Figure 5-24.
            Monitor well locations, ARCO Black Thunder Lease
            (University of Wyoming, 1976).
                              137

-------
CO
00
                  TABLE 5-12.  SUMMARY OF ELEVATION OF WATER LEVEL IN ROLAND COAL, SMITH COAL,
                               AND OVERBURDEN COMPARED TO  ELEVATION OF TOP OF ROLAND COAL AND
                               SMITH COAL (Carter Oil  Co.,  1977)
Roland coal
elevation

Well
site
NRH- 1
NRH- 2
NRH- 3
NRH- 4
NRH-239
NRH-241
NRH-242
NRH-243
NRH-244
NRH-245
NRH-246
NRH-247
NRH-268
Coal Water
top, level,
(ft) Cft)
4,245 4,259
4,171 4,241
4,232 4,363b
4,128 4,155
— —
— —
4,172 4,180
4,235 4,218
4,111 4,123
4,090 4,155
4,017 4,150
4,106 4,204
4,256 4,248
Differ-
ence9
Cft)
+ 14
+ 70
+131b
+ 27
—
—
+ 8
- 17
+ 12
+ 65
+133
+ 98
- 7
Smith coal
elevation
Coal
top,
Cft)
—
4,140
4,195
4,095
4,274
4,131
4,140
4,200
4,065
4,041
3,981
—
4,223
Water
level ,
Cft).
_
4,164
4,187
4,146
4,197
4,113
4,153
4,155
4,129
4,180
4,140
—
4,203
Differ-
ence3
Cft)
_
+ 24
- 8
+ 51
- 77
- 18
+ 13
- 45
+ 64
+139
+159
-
- 20
Roland coal
C+) above
C-) below
Smith coal
water level ,
Cft)
_
+ 77
+176b
+ 9
-
—
+ 27
+ 63
- 6
- 25
+ 10
—
+ 45
Overburden
water leyel
elevation,
Cft)
—
4,244
—
-
-
-
4,126
4,244
-
—
-
4,198
4,276

               Hfater level  (+) above  (-) below top of coal

               3Water level  questionable

-------
     Alluvial  aquifers are an important part of the hydrogeologic conditions
 at the Rawhide mine.  Composed of silt, sand, and gravel, these units are
 moderately permeable.  Saturated thicknesses range from 20 feet at Rawhide
 Creek to 40 feet along Dry Fork Little Powder River (Carter Oil Co., 1977).
 The alluviaraquifer systems are 100 to 1,000 feet wide, and roughly follow
 the meandering courses of the streams.

     The coal  seams carry groundwater in their fractures.  The development of
 the fractures determines the water-bearing characteristics of the coal  aqui-
 fer.  In its mining plan update, Carter Oil Co. (1977) published pump test
 information for only one well, #NRH-2, showing values of 115 gpd/ft for trans-
 missivity in the Roland coal and of 310 gpd/ft for the Smith coal.  Storage
 coefficients were 0.0002 and 0.003 for the Roland and Smith coals, respective-
 ly.  These storage coefficients indicate confined conditions, although  water
 level measurements show that the coal seams are not fully saturated in  some
 areas.  Storage coefficients in these unsaturated areas will be in the  range
 from 0.001 to 0.10.

     The Carter Oil Co. (1977) Plan Update notes that circulation patterns are
 complex and not very well understood.  Relationships among all four aquifers
 will have to be studied and reported.  Water well descriptions are contained
 in Table 5-13.

 Kerr-McGee Jacobs Ranch-

     The Jacobs Ranch mine is relatively dry when compared with mines in the
 northern part of the study area.  Groundwater occurs primarily in the Wasatch
 overburden and in the coal seams.  There is no significant alluvial area,
 and according to Kerr-McGee Coal Corp. (1977), no extensively saturated
 scoria regions have been encountered.

     As shown on Figure 5-25, a scoria-coal contact exists on the eastern and
southern sides of the lease.  Field observations of cuts into the scoria found
that the scoria was essentially dry.  However, Kerr-McGee has not drilled ex-
tensively in the scoria, and the possibility of encountering saturated, highly
permeable material should not be discounted.  Indeed, as the pump test at well
#2 indicates (Table 5-14), scoria in this area contributed water through coal
fractures to establish relatively large transmissivity figures.

     Figure 5-26 indicates that the coal seams at Jacobs Ranch dip to the west.
Confined or semiconfined flow through fractures is probably westward.  Aquifer
thicknesses on the order of 70 feet yielded transmissivity values ranging from
50 to 400 gpd/ft.  However, discharge was not adequately controlled, and these
figures should be substantiated with additional data.  Storage coefficients
computed at observation wells are indicative of confined aquifer conditions.

     Water levels in monitor wells on the Jacobs Ranch mine have remained
relatively stable for 3 years (see Figures 5-27 and 5-28).  As a potentiojnet-
ric surface map for the mining plan update, Kerr-McGee submitted a summary of
water levels from water rights adjudication data.  No contours were drawn, and
the completion depths of the wells were not consistent.  Monitor well informa-
tion at Jacobs Ranch is shown on Figure 5-29 and in Table 5-15.


                                     139

-------
TABLE 5-13.
INVENTORY OF WELLS AND SPRINGS,  RAWHIDE BLOCK NEAR  GILLETTE, WYOMING
(Carter Oil Co., 1977) (see pages 142,  143,  and  144 for explanation
of column headings and supplementary notes)
Ranch or house
Well number identification
(D (2)
51-71-6CBA-1 Mador
51-71 -6CBA-2 Mador
51-71 -CBA-3 Mador
51-71-30BAC Marshall
51-72-4AAC Wagensen
51-72-4CDC Oedekoven
51-72-4BAA Wagensen
51-72-5ADD-1 Oedekoven
51-72-5ADD-2 Oedekoven
51-72-7AAC Wagensen
51-72-7ACA School house
51-72-7DAC Daly
51-72-9CCD Wagensen
51-72-11DDA -Carter
51-72-13DDA Marshall
51-72-16BDD Wagensen
51-72-17CDB Hardy
51-72-18DAA Wagensen
51-72-20AAB Coulter
51-72-20ACB-1 Wandler
51-72-20ACB-2 Wandler
51-72-20ADB-1 Harned
51-72-20ADB-2 Harned
51-72-20BDC Vandekoppel
51-72-20CBA Vandekoppel
al. Alluvium
2. Above Roland coal
3. Roland coal
4. Smith coal
5. Base of burned coal
6. Below Smith coal
Use
(3)
D
D
D
S
S
S
D
D
S
S
D
S
S
S
S
S
D
S
D
D
D
D
S
D
S






Depth Year
• (feet) completed
(4) (5)
208.5
400R
Spring -
Spring -
Spring
149.7
352R
450R 1958R
_ _
Spring -
_ _
_ _
Spring
78.3
60.9
Spring -
127R
Spring
— —
60R 1966R
118R 1973R
250R 1970R
60R
""*" "™"






Type of
power
(6)
None
EP
_
_
—
WM
EP
EP
WM&EP


EP
WM
EP
EP
—
EP
EP
EP
EP
WM
EP
WM






MP
elev.
(feet)
(7)
4168
...
_
4275
4200
4215
_
—
_
4200
—
_
4190
4275
4232
4350
—
—
	
—
:







Depth to
feet
(8)
51.64
—
_
0
0
80.76
30-40R
160R
—
0
5.6
—
70.12
14.07
92R
—
—
^
—
30R







water
date
(9)
5-25-73
—
_
—
4- 6-73
4- 6-73
-
—
—
—
9-26-73
—
6-25-73
6-24-73
1973
~
~"
-
^
-







GPM Date
(10) (11)
_ —
_ —
6R
200R 9-27-73
5E
— —
10R
10R
— ~"
60-70R -
_ —
-" """
0.5 9-26-73
~~ "™
7.5


100R
~ ~
10R







Probable
producing
Used? horizon or
(12) zone3
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
\g
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Vac
TcS
«j
Yes
Yes
\t A A
Yes
MM
NO
Yes







6
6
6
5
1

6

'
1


3

2
7
f
2

1?
7







                                                                                  (continued)

-------
TABLE 5-13 (continued)
Ranch or house
Well number identification Use
(1) (2)
51-72-200CDB Hladkey
51-72-20DDB Hladkey
51-72-21BCB Coulter
51-72-22DAC AMAX coal
51-72-22DCC
51-72-28DAB-1 AMAX coal
51-72-280AB-2 AMAX coal
51-72-29DBB Hladkey
51-73-13ADB Daly
52-72-24BAA Rourke
52-72-25BOB Clark
52-72-26AD Clark
52-72-29DBD Thorpe
52-73-24DDD
52-73-25DCC
(3)
S
S
D
S
S
O.S
S
D
S
S
D,S
S
S
S
D.S
Depth Year
(feet) completed
(4) (5)
68
— —
48R
— —
149.7 1973E
- -
— —
- -
77.0
48.9
Spring
— —
Spring -
115.6
— —
Type of
power
(6)
MM
UM
EP
WM
WM
EP
WM
EP
WM
WM
—
—
—
EP
WM
MP
elev.
(feet)
(7)
4275
—
_
_
4270
—
—
—
4295
4055
-
—
—
—
—
DeDth to water
feet
(8)
12
12
_
_
24.55
—
_
—
60.4
12.09
—
6+
(See
25,09
—
date
(9)
_
—
_
_
6-24-73
—
_
—
7- 7-73
6-24-73
—
9-27-73
notes)
4- 6-73
—
GPM Date Used?
(10) (11) (12)
- - No
Yes
Yes
- - No
— —
Yes
No
Yes
Yes
Yes
10R - Yes
Yes
Yes
2.0+ 4- 6-73 Yes
- - No
Probable
producing
horizon or
zone3
1
?
6
?
2
?
7
?
2
6
6
?
2
2
?

al. Alluvium
2. Above Roland coal
3. Roland coal
4. Smith coal
5. Base of burned coal
6. Below Smith coal

















































-------
                            TABLE 5-13 (continued)

Explanation of column headings:
( 1)   51-71-6CBA-1  example:   51 = T 51  N, 71 = R 71 W, 6 = Section,
       CBA = HE% NWJj SW%, 1 =  well number 1 in this location.

( 2)   Tentative information based on currently available information.

(3)   D = domestic, S = stock
( 4)   Distance in feet from measuring point (MP) to static water level.

(5)   R = reported.  E = estimated by Fisk.

(6)   EP = electric power.  WM = windmill.
(7)   MP = measuring point (usually top of casing).  Plus or minus 10 feet
       accuracy.
( 8)   Distance in feet from measuring point to static water level.

( 9)   Date of water level observation data.
(10)   GPM = gallons per minute.  R = reported.  E = estimated.  + = plus,
       or more than.

(11)   Date of yield data.
(12)   Present use status.  Yes = currently used.  No = currently not used.
 Supplementary Notes:


 51-71-6DBA-1.  USGS card data.  Valley side slope.  Drilled well in pit about
 8 feet deep, 6-inch casing, no pump, no power.  MP about 8 feet below land
 surface.  Water temperature 55° F(bailer  sample),conductivity 1050 on
 5-25-73.

 51-71-6CBA-2.  USGS map data.  New well about 10 feet north of well 51-71-
 6DBA-1.  Conductivity 1000 on 5-25-73.  Photo by Fisk on 9-26-73.

 51-71-6DBA-3.  USGS map data.  Conductivity 500 on 5-25-73.  Photo by Fisk on
 9-26-73.

 51-71-30BAC.  USGS map data.  Spring flowing out of hillside.  Evidently  the
 source of the Little Powder River.  Discharge about 0.5 second feet  (visual
 estimate by Fisk on 9-27-73).  Three photos by Fisk on 9-27-73.  Norman King
 of USGS (Denver) believes that this spring indicates the rate of underflow
 through the coal from the south.

 51-72-4AAC.  USGS card data.  Developed spring in bottom of upland swale.
Water temperature 42° F, conductivity 2350, pH 6.0 on 4-6-73.

51-72-4CDC.  USGS card data.  Upland near ridge top.  Drilled well with 6 inch
casing.  MP about 0.5 feet above land surface.  Good measurements.   Water
temperature 46.5° F, conductivity 1700, pH 6.0 on 4-6-73.
                                       142

-------
                            TABLE 5-13  (continued)

51-72-4BAA.   Pump setting 160 feet reported.  Photo by Fisk on 9-27-73.
51-72-5ADD-1.   Pump setting 200 feet reported.  Good quality water, slight show
of gas reported.  Discharge reported about 10 gpm for one hour, then pump is
off for 15 to 20 minutes, then 10 gpm for an hour, etc.  Photo by Fisk on
9-26-73.
51-72-5ADD-2.   Photo by Fisk on 9-26-73.
51-72-7AAC.   Reported yield of 60-70 gpm for 2 or 3 months, then dry-up for
several months repeat cycle.  Photo by Fisk on 9-26-73, no visible flow at that
time.
51-72-7ACA.   School well in shed behind school.  MP about 0.5 feet above land
surface.  Two photos by Fisk on 9-26-73.  Water softener used.
51-72-7DAC.   Photo by Fisk on 9-27-73.
51-72-9CCD.   Discharge about 0.5 second feet (visual estimate by Fisk) on
9-26-73.
51-72-11DDA.  USGS card data.  Upland.  Drilled well with 6-inch casing.  MP
about 2.6 feet above land surface.  Conductivity 3600 on 6-25-73.  Photo by
Ftsk on 9-26-73.
51-72-13DDA.  USGS card data.  Valley side slope.  Stream (Little Powder River)
in valley.  Drilled well with submersible pump, 6 inch casing.  MP about
13 feet above land surface.  Water temperature 50.5° F, conductivity 925 on
6-24-73.  Old homestead no longer occupied.  Evidently owned by Carter.
51-72-16BDD.  Two-inch steel pipe extends to stock tank about 4 feet wide and
12 feet long, half-full of water on 9-26-73.  Photo by Fisk.
51-72-17CDB.  USGS card data.  Well on top of ridge.  Submersible electric
pump.  Conductivity 1350, pH 6.4 on 4-6-73.  Photo by Fisk on 9-26-73.
51-72-18DAA.  Trickle from pipe on 9-26-73.  Photo by Fisk.
51-72-20AAB.  Drilled by Ruby.  Trench was being dug on 9-26-73 for pipe from
well to prefab houses.  Photo by Fisk.
51-72-20ACB-1.  Well drilled with rotary, on top of coal, gravel packed.  Water
potable but has some rust.  Photo by Fisk on 9-26-73.
51-72-20ACB-2.  Drilled by Western Exploration, 60 feet of sand, 5%-inch casing.
Described as "real gusher."  Photo by Fisk on 9-26-73.
51-72-20ADB-1.  Drilled by Ruby.  Photo by Fisk on 9-26-73.
51-72-20ADB-2.  Photo by Fisk on 9-26-73.
51-72-20BDC.  Reported pump set at about 40 feet.  Reported that yield might
be more with larger pump.  Good quality water.  Photo by Fisk on 9-26-73.

51-72-20CBA.  Photo by Fisk on 9-26-73.
51-72-20CDB.  USGS map data.  Photo by Fisk on 9-26-73.
51-72-20DDB.  Photo by Fisk on 9-26-73.


                                       143

-------
                            TABLE  5-13  (continued)

51-72-21BCB.  Drilled by Buck Williams.   Well near new house on hill.  Described
as "real good well."  Water quality good.  Photo by Fisk on 9-26-73.

51-72-22CAC.  Photo by Fisk on 9-26-73.
51-72-22DCC.  USGS card data.   Upland valley bottom.  MP 0.9 feet above land
surface.  Cylinder pump, 6 inch casing.   Water temperature 55° F (bailer sample),
conductivity 1875.  Photo by Fisk on 9-26-73.
51-72-28DAB-1.  Photo by Fisk on 9-26-73.

51-72-28DAB-2.  Photo by Fisk on 9-26-73.
51-72-29DBB.  Photo by Fisk on 9-26-73.
51-73-13ADB.  USGS card data.  Upland valley bottom.  Drilled well, cylinder
pump, 6-inch steel casing.  MP 0.4 feet above land surface.  Static water mea-
sured with electric tape.  Water obviously high in iron.  Water temperature
49.5° F, conductivity 3400, pH 6.4 on 4-7-73.
52-72-24BAA.  USGS card data.  Upland valley bottom.  Cylinder pump, 6-inch
steel casing.  MP 1.4 feet above land surface.  Water temperature 53° F (Bailer
sample), conductivity 1050 on 6-24-73.
52-72-25DBB.  Stock tank located immediately below spring on hillside.  Domes-
tic water piped from spring to Mrs. Clark's white house east of Highway 59 and
to Mrs. Clark's old red house west of highway.  Photo by Fisk on 9-27-73.
52-72-26ADD.  Not sure if supplied by pipe from spring 52-72-25DBB.  Photo'by
Fisk on 9-27-73.
52-72-20DBD.  Water flows from spring into stock tank.  Reported to  flow year
around.  Flow on 9-26-73 about 0.1 gpm.   Photo by Fisk.

52-73-24DDD.  USGS card data.  Valley side slope.  Drilled well, 6-inch steel
casing, submersible pump.  MP 0.4 feet above land surface.  Good measurements.
Water temperature 51.5° F, conductivity  790, pH 6.4 on 4-6-73.
52-73-25DCC.  Photo by Fisk on 9-27-73.
                                       144

-------
-p*
en
                                                                     ?  CLINKER EDGE (shading toward clinker)



                                                                        LEASE AREA



                                                                        AFFECTED AREA
           Figure 5-25.   Kerr-McGee Jacobs Ranch mine, Thunder Creek area  (Kerr-McGee Coal  Corp., 1977)

-------
                      TABLE 5-14.
SUMMARY OF AQUIFER TEST DATA, KERR-McGEE JACOBS RANCH MINE
(Kerr-McGee Coal Corp., 1977)
-£»
cn

Test
well
No.
36-7

37-3

28-1

12

13

Date
of
test
?

12-5-74
12-5-74
12-7-74
12-7-74
9-28-74

9-28-74

Type Observ.
of well
test No.
Pump _

Sp cap _
Pump 9C-3
Sp cap -
Pump 4C-1
Sp cap -

Sp cap

Length
of test
(min.)
0.5

60
1060
30
164
1440

1440

Prod.
rate
(gpm)
2

5
5
5
1.8
42

49
Final
draw-
down
(ft)
?

22
—
15.5
_
0.4?

145
1 Day
spec.
cap.
(gpm/
ft)


0.17
_
0.04
-
105.0

0.34
Aquifer parameters

Geol.
fin*
Sc & Co

Co
Co
Co
Co
Co

FU

Trans.
(gpd/ft)


400
52
100
112
100.000

500
Aquif.
thick.
(ft)
10

70
60
70
38
108

55
Perm.
(gpd/
ft<0


5.7
0.9
1.4
2.9
930

9

Storage
coeff. Comments
_ SWL at pump bowls -no
recovery after 30 min.
- Erratic pump rate
2.1 x 10-4 Erratic pump rate
- Erratic pump rate
1.3 x 10-5 Erratic pump rate
— No packer-possible leak-
age from overlying scoria
- -

aSc =
Co =
W =
FU =
Scoria
Coal
Wasatch






























Fort Union

-------
                                                                                           4600
                                                                                           "K"
Figure 5-26.  Kerr-McGee Jacobs  Ranch  mine cross section K-K (Kerr-McGee Coal Corp., 1977).

-------
          o
          to
oo
      p  +'
      «c
      LJJ  CD
      UJ

      i
      o
1
                           I
J—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—I—l—f-
           FEB   APR   JUN  AUG   OCT   DEC   FEB  APR   JUN   AUG   OCT   DEC  FEB   APR   JUN   AUG   OCT

                         1974                                1975                               1976


              Figure 5-27.  Static water levels -  Jacobs Ranch mine (Kerr-McGee Coal  Corp.,  1977).

-------
VD    LU

     _l
     UJ
     >
     LU
     _l

     CtL
     LU

     
-------
en
O
            Figure 5-29.  Kerr-McGee  Jacobs  Ranch  mine well  locations  (Kerr-McGee Coal  Corp.,  1977).

-------
                    TABLE 5-15.
DESCRIPTION OF MONITOR WELL COMPLETIONS AT JACOBS RANCH MINE
(Kerr-McGee Coal  Corp., 1977)
en

Location

Well No. a
1C-1
1C-7
1C-15
3C-11
4C-1
5C-2
5C-3
9C-2
9C-3
9C-10
28-1
36-7
37-3
37-7
38-7
39-7
98C-15
102C-15
#2W
#3W


North
1115288
2223011
1107229
1113220
1119276
1115375
1115336
1119281
1119093
1112533
1119114
1112770
1119000
1112775
1112768
1112870
1104610
1104240
1109070
1104590
aC = Converted core
W = Water
well


East'
486954
492322
476318
482038
487046
489363
474966
481732
476362
478736
487102
492819
476474
492886
492598
492464
479250
476450
841920
480900
hole



Sec.
1
7
15
11
1
2
3
2
3
10
1
7
3
7
7
7
15
15
11
14
bSc
Co


(JO
43
43
43
43
43
43
43
43
43
43
43
43
43
43
43
43
43
43
43
43


m
70
69
70
70
70
70
70
70
70
70
70
69
70
69
69
69
70
70
70
70
Grd.
eley.
(ft
\ » **
abv.
msl)
4341.3
4892.2
4756.2
4804.8
4875.4
4820.9
4773.4
4854.8
4807.6
4800.6
4877.4
4847.7
4810.5
4842.4
4869.9
4882.9
4660
4642
4683
4683


Total
180
140
185
160
180
195
220
200
240
170
160
80
240
76
120
140
81
50
180
679


Csg.
180
140
185
160
180
195
220
200
240
170
160
80
240
76
120
140
-
-
163
645
Depths
Packer
base
None
None
None
None
None
None
None
None
None
None
90
None
160
None
None
None
-
-
25
190
(ft.)
Perf.
intv.
80-180
40-140
85-185
60-160
80-180
95-195
120-220
100-200
140-240
70-170
88-160
40-80
160-240
36-76
82-120
100-140
-
-
55-163
413-600

Gravel
pack
X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
-
-
X
-
Type
'/ r""-
of
hole
.
_
.
-
_
_
-
_
-
_
C
C
C
C
C
C
-
.
W
W
Diameters (in.)
Geol
fmb
Coal
Coal
Coal
Coal
Coal
Coal
Coal
Coal
Coal
Coal
Coal
Sc & Co
Coal
Sc
Coal
Coal
-
-
Sc
Sand
Drill
bit
4
4
4
4
4
4
4
4
4
4
9
9
9 •
5-1/8
5-1/8
5-1/8
4-3/4
5
7-7/8
8-3/4

Csg.
1-1/4
1-1/4
1-1/4
1-1/4
1-1/4
1-1/4
1-1/4
1-1/4
1-1/4
1-1/4
5
5
5
2
1-1/4
2
-
-
6
6-5/8
Type
csg.
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
PVC
-
-
-
-
Steel
Steel
State
permit
28904
28905
28906
28907
28908
28909
28910
28911
28912
28913
28708
28706
28707
28709
28710
28711
-
-
29425
29426
= Scoria
= Coal














-------
Sun Oil  Cordero -

     Groundwater  at the  Cordero  mine  has  not  received extensive treatment in the
Corderc  mining plans or  impact statements.  Brief descriptions of the occurrence
and quality of water have been offered,  but supporting maps are not presented.

     Groundwater  exists  in the Wasatch Formation, the coal  beds, the alluviated
area of the Belle Fourche River, and  probably in the scoria.  Cordero has not
published any pump test  results  to aid in the evaluation of these aquifers,  al-
though the environmental impact  statement states that aquifer characteristics
are probably sinrlar to  those at Belle Ayr South (U.S. Geological Survey,
1976).  Field observations at Cordero indicate that the overburden is gener-
ally dry, with the exception of  several  lenticular sandstone beds.  Some water
does emanate from the coal seams, and Cordero estimates that it will pump
between 70,000 and 100,000 gpd from the pit.   No information on scoria aqui-
fers or alluvial  aquifers has been located.

     Water  levels were fairly stable during premining activity, as shown on
Figure 5-30.  These levels were  published in  Cordero Mining Co. (1976).

Wyodak -

     The Wyodak mine has been mining  coal  since  1925.   When compared with the
planned mines on Federal leases, Wyodak is a  relatively small strip mine.  How-
ever, because mining has proceeded for a long period of time, Wyodak's hydro-
geology bears scrutiny.

      Wasatch  and  alluvial aquifers are given minimal  treatment in Wyodak
 Resource  Development Corp.  (1977).  Wasatch aquifers  are described as  having
 "low permeability," although  no  pump  test  data  are  given to  substantiate this
 statement.   Donkey Creek runs north past the south  Wyodak  pit  and turns  to  the
east just in  front of the Neil  Simpson Power Plant  at Wyodak.   From field
observations,  it  is estimated that there is no  more than 20  feet  of alluvium
along the streambed of  Donkey Creek.  Although  parts  of the  alluvium are
saturated,  the alluvial  aquifer is a  minor one.

     Three  separate scoria aquifers are beneath  Wyodak leased  lands.   As shown
on  Figure 5-31, these are the East Burn, the "21" Burn, and  the Ditto  Lake  Burn
(Wyodak Resource  Development Corp., 1977).  Saturated thicknesses in the East
Burn are  on the order of 20 to  30 feet.  Wyodak  feels that a  relatively  imper-
vious layer of slaked coal and ash separates the coal  beds from the highly
permeable East Burn scoria.  The "21" Burn is bordered by  coals on the east
and by layers of clays,  fine sands, and fluvially deposited  ash,  slaked  coal,
and scoria to the west.   Wyodak's consultants feel  that this  layered material
to the west has a low permeability and serves to isolate Wyodak's coal beds
from the  Ditto Lake aquifer.  The Ditto Lake Burn,  covering  688 acres, is the
largest of the Wyodak scoria areas, and it also  has the most water in storage.
Ditto Lake receives internal drainage from local high areas,  and this runoff
serves to recharge the scoria aquifer.  Pumping  tests indicated porosities of
13 percent (Wyodak Resource Development Corp.,  1977)  and specific capacities
of 18 gpm/ft (Rahn, 1976).  The aquifer discharges  to the  coal at the western
                                     152

-------
LU
§
UJ
 50




 60





 70





 80





 90





100





110





120





130






140




150





160

        o
a-  170
O
   180
   '





   190





   200





   210





   220





   230
  8


,  10
            ~"	Plug	^
            \
                   A   "'
                    *





                    \


                     \

                                	
                               ..-——..
                  4,—-'4--?5»C
             v   ^	
                       ' Dry (Total dtp*)
                                                       LEGEND



                                                    7 = MONITORING WELL
        <
      456789  10 1112  1   23456789  10 11 12 12345   678

                1974                        1975                           1976





    Figure  5-30.  Water levels  of monitor holes  at Sun Oil  Cordero mine

                   (Cordero Mining Co.,  1976).
                                       153

-------
en
           WEST
WEST LINE
T50N R71W
                                                WEST LIMIT OF
                                                PROPOSED MINING
                                                                                                          EAST
                                                                BARRIER
                                                                                                  EAST BURN LINE


                                                                                         WYODAK MINE
                                                 *"^T" - ~__L FT. UNION CLAYS AND SANDS
                                 APPROXIMATELY 4 MILES - NOT TO SCALE
                           Figure 5-31.   Idealized east-west cross section of Wyodak site
                                          (Wyodak Resources Development  Corp., 1977).

-------
edge of the burn, to the layered rocks at the eastern edge, and to evapo-
transpiration.

     The coal aquifers at Wyodak are characterized by low permeability according
to Wyodak Resources Development Corp. (1977).

     The north pit is reported to make "very little water" even though water
levels are 90 feet above the pit floor only 2,300 feet to the west (Wyodak
Resources Development Corp., 1977).  Observations at the south pit indicate
that the largest flows are from fractures near parting layers between the
Roland and Smith coals.

     As its potentiometric surface map for its 1977 Mining Plan Update, Wyodak
submitted a partial copy of a U.S. Geological Survey map by King (1974).  This
map (Figure 5-32) included few points on or near the mine, and much of the data
was from wells with openings in more than one aquifer.

     Wyodak Resources Development Corp. (1977) states that there is a ground-
water divide at the mine.  Flows west of the mine are said to be confined in
the coal seam.  To the east, water is said to be unconfined and flowing to the
east in Wasatch Formation aquifers.  Figure 5-33 shows the effects of 50 years
of mining on water levels near the Wyodak pit.

     Wyodak1s groundwater monitoring stations and monitoring schedules are shown
on Figure 5-34 and in Table 5-16.

MODIFIED HYDROGEOLOGY

Watershed Character!sti cs

     Mining of coal will result in several changes in the surface water system
and its relation to groundwater.  The most conspicuous change will be a general
lowering of the land surface where the coal seams are removed.  The overall de-
crease in volume of material (coal and overburden) disturbed by mining will be
slightly less than the volume of coal removed because the overburden increases
slightly in volume when broken up and replaced.

     The lowering of the land surface will increase areas of internal drainage,
or closed basins, on all watersheds affected by mining.  The water budget of a
closed basin created by mining will determine if the basin forms a perennial
lake or becomes dry for long periods.  Surface runoff is a critical factor in
the budget and will determine if a basin that lies below the water table be-
comes a sink for groundwater or a source of recharge.  Existing methods of sur-
face runoff prediction may greatly overestimate runoff volumes (Lowham, 1976).
If runoff volume is much less than estimated, a basin may be a groundwater sink
and concentrate all salts brought in by surface and subsurface flow.

     Recharge quantities under postmining conditions currently are unknown.  In
interstream areas, recharge will depend on modified hydrologic properties of
replaced soil and the configuration of the soil surface.  The surface may be
artificially pitted to encourage infiltration and storage of soil water for
plants.  It is not known if this water will move deep into the subsurface.
Most or all of the water may be consumed by evapotranspiration.

                                     155

-------
en
cr>
    Figure 5-32.  Contours of water  table,  Wyodak area  (from U.S.  Geological  Survey map  I-848-F,  King,  1974),

-------
         DITTO LAKE
                                                                                                     NORTH PIT
01
                                                                                                          — 4410 ft.
                                                                                                        ^ \4311 ft.

                                                                                                            4300ft.
                 Figure 5-33.   Effect of 50 years of mining in Wyodak north  pit  upon  water table
                               (after Wyodak Resources Development Corp.,  1977).

-------
                                                 '     \f

                                                DRILLHOLE
                        __-": ' »*    \>V '•<; *
                       -	  ^ *      * *?i- N- *A

                       ^    .cW
  (^r-      (>v3/'
   v(A,  -  ^  .••;u(
• \ lx* c-; --'s^-./C'-'/
•. •— / ••<7. S^^LS
  si : v\ '.-;-1  c.--j,"
  >>^oV\\;';.    f
  >r •• -'jLLibL-^-^V-
                                         -.-GRAVEl ^G^RAVEL
	.^m^^m^, • -
     ,-<-v ^V-V-  V POWFR PI AWTr _ r  ^-*
                              > POWER PLANT
                                                   ^- —*t iT^
                                           USUBSTA ,^"~  fuj ;
     Figure 5-34.
Locations of monitoring wells, Wyodak mine
(Wyodak Resources Development Corp., 1977),
                          158

-------
TABLE 5-16.  WYODAK GROUNDWATER MONITORING STATIONS
             (Wyodak Resources Development Corp., 1977)

No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Name
3-76
5-76
13-76
11-76
USGS
Ditto Ob-2
Ditto Ob-1
Wi ndmi 1 1
8-76
14-76
15-76
Wi ndmi 1 1
USGS #1
USGS #2
USGS #3
Wyodak #5
Wi ndmi 1 1
Zone monitored
Wyodak coal
Wyodak coal
Sands above coal
Sands above coal
Wyodak coal
Scoria
Scoria
Wyodak coal
Wyodak coal
Sands below coal
Sands above coal
Wyodak coal
Alluvium
Lower Wyodak bed
Upper Wyodak bed
400-foot: sands
below coal
Scoria
Water quality
Every 6 mos.
Start 1992
Every 6 mos.
Start 1992
Every 6 mos.
Start 1992
Every 6 mos.
Start 1992
Every 6 mos.
Start 1992
No check
planned
Every 6 mos.
Start 1992
Every 6 mos.
Start 1992
Every 6 mos!
Start 1992
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
No check
planned
No check
planned
No check
planned
Every 6 mos.
Start 1977
Every 6 mos.
Water level
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mps.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
No check
planned
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
Every 6 mos.
Start 1977
No check
planned
                            159

-------
     Along streambeds established in the soil, infiltration and recharge
 quantities will depend on modified stream properties, such as streambed
 composition, sediment loads, and material beneath the streambed.

     It is possible that overall quantities of recharge to the deep subsur-
 face from rainfall and surface runoff will decrease if near-surface permeable
 clinker and well-sorted alluvial deposits are destroyed.

     The surface hydrology and its relation to groundwater under postmining
 conditions can be seen to be speculative.  Too few data exist to make reliable
 predictions at this time.  Better prediction is expected as mining prog-
 resses and more data are gathered.

 Soils and Infiltration Characteristics

     Determining infiltration characteristics will be necessary when there is
 a possibility of water percolating from the surface through reclaimed areas
 to depths where free water may be present or where there would be free water
 buildup.  Of particular concern are the pollutants which may be picked up and
 transported by these percolating waters.

     The depths to which the water might percolate on a reclaimed mine site
 depend upon:

          •  The configuration of the surface, including slope
             inclination, slope length, surface roughness, and
             surface geometry

          •  The physical characteristics (including porosity,
             texture, depth structure, and collodial content)
             of spoil and topsoil material used for dressing

          •  The amount, temporal distribution, and intensity of
             rainfall and snowmelt; and the rates of evaporation,
             including potential demand and the influence of
             vegetation.

     Rahn (1976) determined infiltration, spoils moisture content, grain size
 analysis, field density of spoils, overburden lithology, and laboratory calcu-
 lations of permeability on samples from several mines in the Powder River
 Basin.  Results of permeability tests are of interest as estimates of the
 hydraulic conductivity of the disturbed vadose zone deposits and the leach-
 ing potential.  Data for two mines in the project area are given below.

     Laboratory permeability values on six samples of overburden from the
Wyodak mine ranged from 6.6 to 38.0 gal/day per ft2, with an average of 14.8
gal/day per ft2 (Rahn, 1976).  Rahn also points out that the overburden at
the Wyodak mine is very thin so that the final open pit will be large but
with little spoils.  Since the water table is high, the end result will be
mainly a lake in the abandoned pit.  Thus, the final vadose zone will be of
minimal  thickness.
                                     160

-------
     Laboratory permeameter test results for overburden samples from the
Belle Ayr South mine ranged from 1.8 to 38.7 gal/day per ft2, with an average
of 12.9 gal/day per ft2.

Vadose Zone Characteristics

     The vadose zone present in spoil following reclamation will consist of
a heterogeneous mixture of overburden material originally present in the
indigenous vadose zone, and shallow aquifer systems.  The overburden material
consists of sandstone, shale, carbonaceous shale, and thin or impure coal beds
of the Wasatch or uppermost Fort Union Formations.  Scoria, or baked shale and
siltstone, may also be present, together with alluvial material.

      Two  consequences  of  modifying the vadose zone  area are:   (1) increased  hy-
 draulic conductivity,  and (2) exposure of  fresh mineral surfaces to percolating
 water (Rahn,  1976).  The  increase  in  hydraulic conductivity is a reflection  of
 the  overall  increase in volume  and porosity of spoil formations as compared  to
 natural formations.  Obviously, the new vadose zone will be highly heteroge-
 neous and  anisotropic.  For example,  spoil dumped into the pit by truck will
 tend to separate out by gravity as it tumbles down  the embankment.  The method
 of placing spoils in the  pit also  appears  to have an effect on hydraulic pro-
 perties.   For example, Rahn  (1976) obtained an average permeability of 450 gpd/
 ft2  at the Hidden Water Creek mine with dragline-emplaced spoils, but only
 4 gpd/ft2  at the Bighorn  coal mine with scraper- and bulldozer-emplaced spoils.

      A consequence of  the increased hydraulic conductivity of the vadose zone
 is that infiltrated surface water  will migrate more readily through the depos-
 its, leaching salt into the shallow aquifers.  Rahn (1976) described the mech-
 anism involved in leaching as follows:

           "Rocks are generally  broken during mining, thus allowing
           fresh mineral  surfaces  to  be exposed to  percolating wa-
           ters.  While precise hydro-geochemical reactions are
           difficult to predict,  it can be stated  ... that the equi-
           librium soil-water-mineral conditions which had been
           established ... over thousands  of years  are changed by
           mining, and with the infiltration of infiltrating rain-
           water or percolating groundwater in the  spoils, more
           rapid weathering reactions can  commence."

      Observations by Rahn at several  mine  sites in  the Powder River Basin il-
 lustrated  that the salinity of  water  samples from the spoils was markedly
 greater than  in native groundwater.

      The manner in which  surface water is  applied to the spoil pile area may
 have an effect on leaching in the  vadose zone.  If  the area becomes inundated,
for  example  by flood water, water  will move downward in the saturated state,
 leaching and  transporting salts through large cracks or pores.  With rainfall
.or light application of surface water, however, water will move downward in
the  unsaturated state.  Consequently, water movement will be preferentially  in
the  smaller  pore spaces.   Field experiments  (Biggar and Nielsen,  1967) on
leaching have shown that  greater leaching  occurs with unsaturated flow than


                                    161

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with saturated flow.  That is, the potential effect on groundwater quality by
unsaturated flow following a rain is much greater than from surface inundation.
However, because of the slow velocity of unsaturated flow, the effects may not
be evident for years or centuries.

     Another consequence of modifying the hydrogeologic properties of the
vadose zone at mine sites is possible.  In particular, perching layers may be
disrupted by stripping.  Consequently, water moving laterally through mounds
in the vadose zone will intersect and flow into the modified region, and move
downward toward the water table.  Leaching will, therefore, result around the
periphery.

Aquifer Characteristics

      In general, considerable disruption of aquifer characteristics can occur
during mining.  As  the coal aquifer commonly is the most  productive and the coal
 is  to be removed,  in one  sense the aquifer is destroyed.  However, in this dis-
cussion, the concern is with the  reclaimed area, namely the spoils.  In a sense,
the  aquifer will remain,  but the  materials will be different than those origi-
 nally present and  the  hydraulic characteristics will be different.  Modifica-
tions of the vadose zone  have been previously described.  Groundwater at most
mines is in the coal,  in  the underlying materials, and sometimes in the over-
 burden.  The coal  and  overburden  vary greatly in the degree of consolidation;
 however; groundwater is generally considered to be moving through fractured con-
solidated rock except  for the alluvium.

      Three major cases to consider are:

            •  Removal  of coal and replacement with spoils;

            •  Removal  of alluvium and replacement with spoils; and

            •  Removal  of overburden and replacement with  spoils.

      Rahn (1976) reported on two  pump tests in spoils near Sheridan, Wyoming.
However, the test at the Big Horn Mine yielded very questionable results and
the  reported values of transmissivity are considered unreliable.  At the Hidden
Creek Mine, a 27-hour  pump test was conducted on a well tapping about 33 feet
of spoils.  About 21 gpm were pumped and the specific capacity was 1.7 gpm per
foot of drawdown.  The transmissivity was about 11,000 gpd per foot and the
storage coefficient was 0.12.  With an average saturated  thickness of 24.5
feet, the permeability of the spoils was 450 gpd per square foot.  Laboratory
permeabilities reported by Rahn for spoils probably have  little meaning with
respect to aquifer characteristics.  Additional pump tests are needed to assess
the  hydraulic characteristics of  spoils.

Removal of Coal -

     Transmissivities for coal aquifers in the Gillette area commonly range
from about 100 to 3,500 gpd per foot.  Values less than 1,000 gpd  per foot are
common and are typical  of fractured hard rock.  Replacement of coal  by  spoils
would appear to result in an increased transmissivity, particularly  if


                                     162

-------
coarse-grained overburden is predominant in the spoils.  However, a predomi-
nance of fine-grained overburden could result in a lower transmissivity.
Also, the spoils are unconsolidated in macrostructure.  Small pieces of
relatively consolidated, fractured materials may remain in the spoils.  In
any case, the net surface area exposed would appear to be greatly increased.
Also, groundwater may flow through spoils as if it were a granular porous
medium as opposed to a fractured hard rock aquifer.  The storage coefficient
would appear to be much greater for spoils than for coal, and obviously the
porosity of spoils would be greater.  The geochemical composition of the
spoils is greatly different from that of coal.


Removal of Alluvium —

     The hydraulic characteristics of alluvium are poorly known in the Gillette
area.  However, the transmissivity is likely low because of the small saturated
thickness.  Presently, the alluvium serves as the point of interchange between
surface water and groundwater.  That is, percolating streamflow in some areas
passes through the alluvium to underlying formations.  Also, groundwater moving
from underlying formations in some areas passes through the alluvium and enters
streams to become surface water.  The replacement of alluvium with spoils could
have profound effect on surface water as well as groundwater.  More or less
percolation from streamflow could occur than under the original conditions.
Also, base flow conditions in the streams could be increased or decreased.  It
is likely that the  spoils are less permeable than the alluvium.  The geochem-
ical composition of the spoils is generally different than that of the alluvium.

Removal of Overburden —

     Transmissivities of several hundred to several thousand gpd per foot are
common for the Fort Union and Wasatch Formations.  When the materials overlying
the coal are broken up and replaced as spoils, both permeability and storage
coefficient should  be increased.  The geochemical composition of the spoils is
basically the same; however, the surface area exposed is greatly increased.
                                   163

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                                 SECTION 6

                        EXISTING GROUNDWATER QUALITY
 REGIONAL
     Shallow groundwaters in the project area have poor chemical quality. Analy-
 ses performed by the coal companies cover a large part of the project area, and
 these results indicate that few of the shallow groundwaters meet EPA drinking
 water standards.  Other analyses of shallow waters, published by Hodson (1971),
 indicate that water quality can vary widely in the project area.  Regional water
 quality was studied by the U.S. Geological Survey (King, 1974) and most waters
 in the area were determined to be of marginal quality.  This work did not speci-
 fy which analyses were from coal aquifers or from Wasatch Formation aquifers.
 Preliminary field tests of City of Gillette Wasatch Formation wells yielded TDS
 values between 1,200 and 3,800 ppm.   The City mixes this poor water with higher
 quality water from deeper Fort Union Formation aquifers to meet drinking water
 standards.

     Groundwaters in the Wasatch Formation are usually of the calcium sulfate
 type.  Analyses published by the coal companies, the State of Wyoming, and the
 U.S. Geological Survey indicate that TDS ranges from 500 to 6,000 ppm, with
 most analyses falling in the 2,000- to 4,000-ppm range.  The lowest values are
 often found in wells near surface streams, and probably reflect the interaction
 of the groundwater and surface water.  pH values for Wasatch waters range from
 7.7 to 8.1.  Trace element studies conducted on Wasatch water samples by the
 coal companies indicate that problems possibly may exist with the following ele-
 ments:  arsenic, cadmium, lead, selenium, and possibly uranium.

     Coal-seam waters can have dynamic characteristics, changing from calcium
 sulfate waters to sodium bicarbonate waters as the water migrates downdip.  The
 ARCO Black Thunder mine's groundwater quality contains a good example of this
 change.  Coal-seam TDS values for the project area range from 500 to 3,500 ppm
 with most values in the 1,000- to 3,000-ppm  interval.  Values for pH range from
 6.9 to 8.2 in coal aquifer waters, indicating that coal aquifer waters are
 neutral to slightly alkaline.  Trace elements of concern include, but are not
 limited to, arsenic, cadmium, copper, lead, and selenium.

     The following discussions are based on data published by the mining  com-
 panies in various documents.  To properly execute the TEMPO methodology,  exist-
 ing groundwater quality must be studied directly adjacent to  the  pollution
 source,  so that changes induced by the source can be determined.  The  data
 presented in this section yield interesting background  information,  but  existing
groundwater quality at each important pollution source must  be  accumulated.


                                    164

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     During their first 2-1/2 years of operation, AMAX Belle Ayr workers
have collected numerous groundwater quality samples.  Although detailed
sample collection procedures were not outlined in the AMAX Coal Co. (1977)
mining plan update, results of several analyses were reported.  Tables 6-1
through 6-4 show the maxima and minima of these results, as well as the mean
values.  Significant deviations occur for some parameters, indicating a
dynamic quality situation or sampling and analytical inconsistencies.

     In its mining plan update, AMAX states that the dominant water types
within the Wasatch Formation are sodium sulfate and sodium bicarbonate.
However, selected samples from the Wasatch Formation (Table 6-1) would be
classified as a calcium sulfate water.  AMAX should include analyses which
reflect the reported sodic quality of their Wasatch waters.  Sodic waters are
shown to exist in the Wyodak coal seam.  Table 6-2 indicates that water types
vary from sample to sample and that the coal seam waters can be either sodic
or calcic.  These results confirm the need for further testing to pinpoint
water quality types on the Belle Ayr lease.  AMAX's deep Fort Union water at
well station WRRI 7 has very high sulfate contents for a potable water
source.  AMAX did not present data on other Fort Union wells which are report-
edly used for office and shop requirements.  The analyses presented for the
scoria pit (Table 6-3) has a close epm balance (0.97), but the reported elec-
trical conductivity is inconsistent with the rest of the results.  If this
inconsistency is ignored, the scoria pit water appears to be of fairly good
quality.  However, the relative amounts of groundwater inflow and surface
runoff that make up this pit water are unknown, and it is assumed that
groundwater within the scoria is not as good as this analysis might indicate.

     AMAX has, published water quality data for its Eagle Butte mine in its
Federal environmental impact statement and in its AMAX Coal Co. mining plan
update (1977a).  This summary is based primarily on the data shown in the
mining plan update.  Analyses were performed by the Wyoming Department of
Agriculture, and equivalent balances ranged from 0.94 to 1.31.  Maximum and
minimum values for water on the Eagle Butte lease are given in Table 6-5.
Sample collection procedures are given in Table 6-6.

     The chemical quality data presented by AMAX indicate that large varia-
tions can exist in groundwater quality at the Eagle Butte lease.  Although
some waters are low in total dissolved solids, most waters exceed drinking
water recommended standards for dissolved minerals.  Eagle Butte waters are
predominantly of the calcium sulfate type.  AMAX has published a single
analysis for each well at the lease.  Quality variations with time are re-
portedly being studied (AMAX Coal Co., 1977a).

     ARCO and the University of Wyoming have conducted fairly extensive
groundwater quality tests.  The University received funding from the EPA to
conduct its research at Black Thunder.  Tables 6-7 and 6-8 show the analysis
presented in ARCO's Final  Environmental Assessment (University of Wyoming,
1976).   Figure 6-1  gives the well locations; Table 6-9 summarizes these data.
Cation-anion balances for selected analyses yield ratios ranging from 0.84
to 1.20,  indicating fairly good analytical control.
                                   165

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TABLE 6-1.   AMAX BELLE AYR WATER QUALITY DATA-WASATCH  FORMATION
             ABOVE THE COAL  (AMAX Coal Co., 1977)

Parameter
Field pH (units)
Calcium
Magnesium
Sodium
Potassium
Carbonate
Bicarbonate
Oil and grease
Sulfide
Arsenic
Barium
Boron
Cadmium
Copper
Total chromium
Chromium-Cr'f6
Total iron
Dissolved iron
Lead
Manganese
Mercury
Nickel
Selenium
Number of
analyses
1
12
12
12
11
12
10
12
4
5
5
5
5
5
4
1
8
8
5
5
4
5
4
Maximum
value
7.5
279.
208.
200.
13.0
610.
705.
21.6
0.9
0.007
0.5
0.6
0.014
0.01
0.1
0.01
5.7
5.0
0.1
0.27
0.001
0.1
0.002
Minimum
value
7.5
180.
59.0
113.
0.0
0.0
500.
0.0
0.0
0.007
0.5
0.0
0.01
0.01
0.1
0.01
0.1
1.8
0.01
0.1
0.001
0.1
0.001
Mean
7.5
213.
145.
164.
9.52
101.
604.
2.55
0.3
0.007
0.5
0.164
0.0108
0.01
0.1
0.01
2.59
3.20
0.082
0.180
0.001
0.1
0.0013
Standard
deviation
-
30.6
37.2
27.6
4.80
237.
51.0
6.08
0.408
-
-
0.246
0.0018
-
-
1.70
1.19
0.0402
0.0623
_
-
0.0005
   Notes:  Values  in ppm unless  specified
         Well  station N-5
         June  1972 to June 1976
                                                             (continued)
                              166

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                    TABLE  6-1 (continued)
Number of Maximum
Parameter analyses value
Silver
Zinc
Kjeldahl nitrogen
*
Conductivity (mmhos)
Ammonia
Organic nitrogen
Nitrate + Nitrite
Chloride
Fluoride
Cyanide
Sulfate
Phenol
NBAS
BOD
COD
Total dissolved solids
Suspended solids
Suspended volatile solids
Lab pH
Turbidity (JTU)
Total carbonate (CO,)
Hardness (CaCOj)
Alkalinity (CaC03)
5
5
11
12
6
1
1
12
9
4
12
5
5
1
12
12
7
6
11
7
11
12
3
0.5
'0.12
1.0
2760.
0.0
0.9
0.0
46.0
0.6
0.02
1369.
0.034
0.14
31.0
28.4
2300.
178.
100.
7.9
29.0
310.
1550.
516.
Minimum
value
0.05
0.01
0.3
1580.
0.0
0.9
0.0
16.0
0.3
0.008
650.
0.0
0.1
31.0
0.4
1480.
8.0
0.0
7.2
1.3
250.
742.
346.
Mean
0.41
0.052
0.682
2211.
0.0
0.9
0.0
21.9
0.511
0.011
980.
0.0074
0.108
31.0
8.71
1877.
38.4
22.3
7.53
10.9
294.
1138.
454.
Standard
deviation
0.201
0.0432
0.252
310.
-
-
-
8.17
0.105
0.006
205.
0.0149
0.0179
-
9.19
250.
61.7
38.7
0.211
9.76
16.7
211.
93.8
Notes:  Values in ppm unless specified
       Well station N-5
       June 1972 to June 1976
                              167

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  TABLE 6-2.  AMAX  BELLE AYR WATER QUALITY DATA-WYODAK COAL
              (AMAX Coal Co., 1977)
Parameter
Field pH (units)
Calcium
Magnesium
Sodium
Potassium
Carbonate
Bicarbonate
Oil and grease
Sulfide
Arsenic
Barium
Boron
Cadmium
Copper
Total chromium
Chromium-Cr
Total iron
Dissolved iron
Lead
Manganese
Mercury
Nickel
Selenium
Number of Maximum
analyses value
1
12
12
12
10
12
12
12
4
5
5
5
5
4
4
1
9
7
5
5
4
5
4
7.0
360.
320.
640.
14.0
0.0
560.
12.1
1.1
0.007
0.5
1.1
0.01
0.01
0.1
0.01
5.1
2.5
0.1
2.0
0.001
0.1
0.001
Minimum
value
7.0
180.
12.0
103.
8.8
0.0
290.
0.0
0.1
0.007
0.5
0.0
0.001
0.01
0.1
0.01
0.2
1.49
0.02
0.1
0.001
0.1
0.001
Mean
7.0
208.
91.4
210.
11.7
0.0
510.
2.34
0.525
0.007
0.5
0.27
0.0082
0.01
0.1
0.01
2.19
2.07
0.084
0.774
0.001
0.1
0.001
Standard
deviation
-
49.1
75.2
138.
1.44
-
74.1
3.55
0.505
-
-
0.465
0.004
-
-
1.65
0.379
0.0358
0.839
-
-
-
Notes:  Values in  ppm unless specified
       Well station N-3
       June 1972  to June  1973
                                                               (continued)
                              168

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                     TABLE  6-2  (continued)
Number of Maximum
Parameter analyses value
Silver
Zinc
Kjeldahl nitrogen
Conductivity (mnhos)
Ammonia
Organic nitrogen
Nitrate + Nitrite
Chloride
Fluoride
Cyanide
Sulfate
Phenol
MBAS
BOD
COD
Total dissolved solids
Suspended solids
Suspended volatile solids
Lab pH
Turbidity (JTU)
Total carbonate (CO,)
Hardness (CaCOg)
Alkalinity (CaC03)
5
5
11
12
6
1
1
12
10
4
12
5
5
1
12
12
8
6
11
8
11
12
3
0.5
2.3
3.9
4740.
1.3
3.1
0.0
31.0
1.3
0.02
3400.
0.005
0.16
20.0
345.
5160.
232.
40.0
7.9
125.
270.
2200.
450.
Minimum
value
0.05
0.08
1.1
1720.
0.0
3.1
0.0
3.6
0.4
0.008
680.
0.001
0.1
20.0
28.0
1400.
8.0
6.0
7.0
5.0
140.
530.
225.
Mean
0.41
0.56
2.59
2077.
0.283
3.1
0.0
9.16
0.75
0.011
940.
0.0026
0.112
20.0
71.6
1785.
68.2
21.8
7.23
29.4
251.
896.
373.
Standard
deviation
0.201
0.974
0.856
841.
0.523
-
-
7.46
0.222
0.006
774.
0.0013
0.0268
-
88.4
1063.
74.7
11.9
0.246
40.0
37.7
422.
128.
Notes:  Values in ppm unless specified
       Well station N-3
       June 1972 to June 1973
                               169

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TABLE 6-3.   AMAX BELLE AYR  WATER  QUALITY DATA-SCORIA PIT-WASATCH
            FORMATION ABOVE THE COAL  (AMAX Coal Co., 1977)
Number of
Parameter analyses
Field pH (units)
Calcium
Magnesium
Sodium
Potassium
Carbonate
Bicarbonate
Cadmi urn
Copper
Total iron
Lead
Manganese
Mercury
Silver
Zinc
Conductivity (mmhos)
Chloride
Sulfate
Hardness
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Maximum
value
7.6
160.
25.0
45.0
18.0
0.0
156,
0.001
0.01
0.07
0.01
0.002
0.002
0.05
0.02
504.
29.0
456.
21.0
Minimum
value
7.6
160.
25.0
45.0
18.0
0.0
156.
0.001
0.01
0.07
0.01
0.002
0.002
0.05
0.02
504.
29.0
456.
21.0
Mean
7.6
160.
25.0
45.0
18.0
0.0
156.
0.001
0.01
0.07
0.01
0.002
0.002
0.05
0.02
504.
29.0
456.
21.0
 Notes:  Values in ppm unless specified
         Well station scoria pit
         dune 1972 to June 1976
                                 170

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 TABLE 6-4.  AMAX BELLE  AYR WATER QUALITY  DATA-FORT UNION
              FORMATION BELOW COAL (AMAX Coal  Co.,  1977)

Parameter
Field pH (units)
Calcium
Magnesium
Sodium
Potassium
Carbonate
Bicarbonate
Oil and grease
Sulfide
Arsenic
Barium
Boron
Cadmium
Copper
Total chromium
+6
Chromium-Cr
Total iron
Dissolved iron
Lead
Manganese
Mercury
Nickel
Selenium
Number of Maximum
analyses value
1
12
12
12
9
12
12
12
4
5
5
5
5
5
4
1
8
8
5
5
4
5
4
7.7
227.
85.0
243.
10.0
0.0
440.
6.0
3.0
0.02
0.5
0.6
0.01
0.01
0.1
0.01
2.2
1.9
0.1
0.23
0.001
0.1
0.001
Minimum
value
7.7
121.
36.0
154.
8.8
0.0
331.
0.0
0.0
0.007
0.5
0.0
0.001
0.01
0.1
0.01
0.1
0.27
0.01
0.0
0.001
0.1
0.001
Standard
Mean deviation
7.7
157.
46.4
220.
9.33
0.0
398.
1.72
1.07
0.0096
0.5
0.158
0.0082
0.01
0.1
0.01
0.788
0.853
0.082
0.118
0.001
0.1
0.001
-
26.1
12.6
23.3
0.377
-
25.1
2.01
1.39
0.0058
-
0.249
0.004
-
-
-
0.709
0.537
0.0402
0.0823
-
-
-
Notes:  Values in ppm unless specified
       Well station WRRI 7
                                                             (continued)
                              171

-------
                     TABLE 6-4  (continued)
Number of Maximum
Parameter analyses value
Silver
Zinc
Kjeldahl nitrogen
Conductivity (mmhos)
Ammonia
Organic nitrogen
Nitrate + Nitrite
Chloride
Fluoride
Cyanide
Sulfate
Phenol
MBAS
BOD
COD
Total dissolved solids
Suspended solids
Suspended volatile solids
Lab pH
Turbidity (JTU)
Total carbonate (CO,)
Hardness (CaC03)
Alkalinity (CaC03)
4
5
11
12
6
1
1
12
9
4
12
5
5
1
11
12
7
6
11
7
11
12
3
0.5
0.44
3.5
1870.
0.3
1.5
0.0
46.0
1.6
0.02
770.
0.047
0.5
9.0
18.0
1500.
206.
108.
7.8
44.0
220.
700.
300.
Minimum
value
0.05
0.04
0.4
1600.
0.0
1.5
0.0
3.6
0.3
0.000
600.
0.001
0.1
9.0
1.2
1270.
4.0
0.0
7.3
0.7
190.
450.
162.
Mean
0.387
0.132
1.81
1791.
0.05
1.5
0.0
12.1
0.555
0.011
728.
0.012
0.18
9.0
8.16
1400.
47.7
29.3
7.48
10.0
199.
572.
274.
Standard
deviation
0.225
0.172
0.785
80.1
0.122
-
-
11.7
0.397
0.006
47.5
0.0197
0.178
-
6.30
62.9
72.6
44.0
0.166
15.3
8.39
58.4
96.9
Notes:  Values in ppm unless  specified
       Well station WRRI 7
                                172

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TABLE 6-5.   MINIMUM AND MAXIMUM VALUES FOR WATER QUALITY PARAMETERS AT
            AMAX EAGLE BUTTE LEASE (all aquifers) (AMAX Coal  Co.,  1977a)

Constituent3
Silica
Calcium
Magnesium
Sodium
Potassium
Bicarbonate
Carbonate
Sulfate
Chloride
Fluoride
Nitrate
Boron
TDS
Hardness (Ca + Mg)
Specific conductance
(mmhos)
pH (units)
Minimum
14
79
20
11
2.8
150
0
73
1.2
0.7
0.1
0
336
240
507

7.1
Maximum
38
375
420
540
44
1300
0
2800
25
1.5
23
3.6
6600
2600
9960

8.0
         JValues in ppm unless specified otherwise
                                   173

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         TABLE 6-6.  SUMMARY OF WATER SAMPLING PROCEDURES DURING TESTS OF VARIOUS
                     WELLS AT THE EAGLE BUTTE  MINE  (AMAX Coal Co., 1977a)
Well
No.
BAN-1A
BAN-3
BAN- 4
BAN-5
GN-6
GN-7
GN-8
GN-9
GNH-6B
Spring
•••••••••••IMH^HMMH
Date
12/23/75
8/19/75
8/19/75
8/19/75
12/18/75
1/6/75
1/7/75
1/7/75
8/19/75
8/18/75
(••^••••PV^HIlmVI^^^HI^M^HIV^BHIV^-^
Aqui f er
Wasatch?
Coal
Coal
Coal
Coal
Coal
Coal
Ft. Union
Alluvium
Alluvium?
•^•MI^Hh4*MH11M«^1111111l«p4BIIIII^— ^^IBBI^^^—a
Elapsed
pumping
time
(hrs)
3.42
0.63
0.88
0.65
0.80
4.50
0.65
10.33
1.33
Artesian
flow?
^MI^^^HIHh^H.vailBW»«_4v^Mh^^^*Bl*«
Volume
water
produced
(gal)
41a
285
413
133
57
567
532b
1C
112
—
Well site tests
Specific
conductance
(mmhos)
2800
3220
1800
1310
1370
1700
1750
—
—
MIIIM>*VIIIIIWMIIIII1IP«MIIIII*IPqlMIIMV*IIIW*IMIIIH«
PH
8.0
7.0
7.2
7.2
8.0
7.8
7.4
—
7.4
7.9
•HKII*MI«IIIIHM-milllllllllHWIIII««
Temp
TO
11.7
13.9
15.5
13.3
11.7
11.7
11.1
--
15.0
13.3
•HIIHII^tfklllllllllWIIIIIWIIIIVIHffMAA
Final
drawdown
(ft)
30
28.9
57.9
3.2
27.2
10.5
•x.0.1
^30
—
- - •. IP :mamf— •— ••a— •»
 Yellow color
 1169 gallons pumped on 1/6/75
Drilling fluid, not sampled

-------
     TABLE 6-7.  RESULTS OF CHEMICAL  ANALYSES OF GROUNDWATER FROM
                 WASATCH WELLS  (University of Wyoming,  1976).
Sample
W-l
W-2
W-2
W-3
W-4
W-4
W-5
W-5
W-6
W-6
W-7
W-7
W-10
W-10
W-ll
R-15A
Average
Minimum
Maximum
Sampl e
date
9/19/73
3/31/73
2/26/75
10/4/73
10/3/73
12/3/73
10/4/73
12/3/73
10/4/73
12/3/73
7/3/73
12/3/73
5/8/73
2/26/74
10/4/73
12/3/73



Laba
ARCO
ARCO
UW
ARCO
ARCO
UW
ARCO
UW
ARCO
UW
ARCO
UW
ARCO
UW
ARCO
UW



ppm
318
340
155
316
764
700
510
452
238
245
200
269
420
395
281
67
354
67
764
ppm ppm
- 121
- 710
0.18 458
8
385
23 484
- 197
90 186
49
7 19
47
8 34
100
0.3 128
33
9 156
20 195
0.18 8
90 710
ppm
82
230
222
112
346
479
46
55
58
22
49
25
66
56
24
57
120
22
479
Alkb
ppm
454
200
-
159
647
660
157
161
634
465
785
804
433
-
805
166
480
159
805
S04=
ppm
610
3100
1900
1160
3200
3456
1650
1440
275
238
52
35
990
630
51
598
1220
50
3500
cr
ppm
84
47
14
11
113
183
39
14
46
28
53
37
34
7
46
2
47
2
183
Si02
ppm
9
8
-
5
21
20
5
9
10
11
13
13
13
-
10
12
11
5
21
TDSc'd
ppm
(1680)
1610
(4635)
4340
3290d
(1770)
1206
(5476)
4823
6000
(2604)
2340
2408
(1310)
1250
1035
1200
1225
(2056)
1890
2094d
(1250)
675
1067
2440
1035
6000
PH
7.4
7.7
7.5
7.4
6.6
-
7.4
-
7.3
-
7.5
-
7.6
7.8
7.5
-
-
-
-
aARCO,  Atlantic Richfield Co.; UW, University  of Wyoming.
Nitration alkalinity reported as HCO-3.
cValues in parentheses obtained by summing individual constituents.
 Alkalinity  (calculated by difference) used to compute TDS.
                                     175

-------
     TABLE 6-8.   RESULTS  OF CHEMICAL  ANALYSES OF  GROUNDWATER FROM
                  ROLAND COAL SEAM WATERS (University of Wyoming, 1976)

Sample
R-l
R-2
R-3
R-4
R-5
R-6
R-7
R-8
R-8
R-8
R-8
R-9
R-9
R-10A
R-10D
R-ll
R-12A
R-12C
Sample
date
9/19/73
10/4/73
10/3/73
10/4/73
8/31/73
8/31/73
10/4/73
7/3/73
9/11/73
9/19/73
12/3/73
7/3/73
12/3/73
7/3/73
12/3/73
5/31/73
6/15/73
12/3/73
Lab3
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
ARCO
UW
ARCO
UW
ARCO
ARCO
UW
Na+ K*
ppm ppm
217 -
127 -
87 -
214 -
165 -
290 -
251 -
410 -
260 -
235 -
249 8
400 -
407 13
65 -
100 57
380 -
150 -
211 14
Ca++
ppm
38
49
283
45
55
360
57
305
72
43
26
103
85
380
294
82
150
203
ppm
43
174
132
21
49
145
33
123
34
27
27
49
46
145
211
35
59
75
Alkb
ppm
781
1049
201
750
790
520
833
475
780
802
600
875
700
585
760
1080
710
514
S04=
ppm
23
410
1160
58
<5
1530
90
1670
210
11
180
550
620
1130
1152
167
340
706
cr
ppm
57
31
33
27
40
40
33
25
25
59
13
30
13
23
2
40
23
3
SiOo
Ppm
8
9
12
8
8
13
8
6
8
8
11
11
12
30
18
7
14
14
TDSc*d
ppm
(1167)
774
(1848)
836
(1908)
2210
(1120)
616
(1110)
680
(2430)
2660
(1305)
777
(3010)
2810
(1390)
1030
(1185)
744
1115
(2020)
1790
1896
(2360)
2390
2594
(1791)
1160
(1446)
1100
1740
PH
7.3
7.5
7.3
7.6
7:2
7.0
7.5
7.3
7,1
7.4
-
7.1
-
6.8
-
7.7
7.2
-
aARCO,  Atlantic Richfield Co.; UW, University of Wyoming.
 Titration alkalinity  reported as HCO-,.
c
 Values in parentheses obtained by summing individual  constituents.
 Alkalinity (calculated by difference) used to compute IDS.
                                                                    (continued)

                                   176

-------
                          TABLE  6-8  (continued)
        Sample
                       Na+   K+    Ca++  Mg++  Alkb   S04=  CT  Si02  TDSc'd
Sample   date    Lab   ppm   ppm   ppm   ppm   ppm   ppm    ppm  ppm     ppm    pH

                                                                      (1438)
                                                                      1130   7.4
R-12D   10/4/73  ARCO   34   -     148


R-12E   7/3/73   ARCO  140   -      30

R-13    5/31/73  ARCO  490   -     230


R-14    5/24/73  ARCO  375   -     119
R-14    2/26/74  UW    300   0.24   97


R-15B   5/31/73  ARCO  340   -      72

R-17A   7/3/73   ARCO  264   -     200
49    512   670   20


18    420    45   50

91   1240   886   54
                                                                     ( 711)
                                                                 8     500   7.8
                                                                     (3000)
                                                                      2380   7.4
8
                                          20
      872   380   60   22
    (1848)
     1440   7.7
                                          33     -     355    9    -    1600d  7.9
                                                                      I
                                          35   1040   160   40    10

                                          73
                            (1700)
                             1170   7.6
                            (1970)
      530   850   40   10    1765   7.0
                                                                      (1655)
R-151 7/27/73
R-151 2/26/74
R-153 7/27/73
R-153 12/3/73
R-154 8/31/73
R-156 10/9/73
R-156 12/3/73
Average
Minimum
Maximum
ARCO
UW
ARCO
UW
ARCO
ARCO
UW



130
90
126
85
185
68
100
217
34
490
0.11
-
6
.
_
8
13
0.11
57
220
203
305
203
430
152
247
165
26
430
80
83
114
76
230
80
103
79
18
230
520
450
0
670
162
485
658
0
1240
650
560
1050
883
1750
660
808
616
<5
1750
40
8
30
15
40
16
2
29
2
59
15
17
24
20
120
30
17
4
120
1270
1509d
(2090)
2050
1292
(3325)
3100
(1260)
954
1783
1770
711
3325
7.4
6.9
7.9
-
7.2
7.3
-
-
-

 ARCO, Atlantic Richfield Co.; UW, University of Wyoming.
 Titration Alkalinity reported as HCO~3.  ,
cValues in parentheses obtained by summing individual  constituents.
dAlkalinity (calculated by difference) used to compute IDS.
                                     177

-------
^_f R 70 W

A
17
(R)« commercia
A
R4
W3
16
1 well
R5«W4
20
R7
W5






R8 •


|
n O '
21
W6A _
RI7A
•21
•
•
W9
W
A
LEGEND
m MONITORED WELLS ON SITE
W2
BT-77
A
1_
L-i
1 — •
R9»W7 »RIOA
3
IWI2
Rj54 Sil° 2
BT-66 * *(PR)
(R)
• • RI53
RI5I •
RI2A«(PR) «RI56

RI4
IDA
t

RI3
34 * 35 _
R'.5B T43N
Wll T42N
3 2

A STOCK WATER WELLS
CONTINUOUS RECORDER ON
* ROLAND FORMATION WELL



0 4000 BOOO FEET
SCALE
Figure 6-1.   Groundwater  gaging network at the Black Thunder Site
             (PR =  Pre-Roland well; R = Roland well; W = Wasatch well)
             (University  of Wyoming, 1976)
                                 178

-------
TABLE 6-9.  SUMMARY OF WATER QUALITY AT BLACK THUNDER SITE SURFACE AND
            GROUNDWATER (values in ppm) (University of Wyoming, 1976)
                                         Range in       Range  in
                                        Roland coal      Wasatch
    Water quality  characteristics         aquifer       aquifer
    Major constituents
      Calcium                               26-430         8-710
      Magnesium                             18-230        22-479
      Sodium                                34-490        67-764
      Sulfate                               <5-1750        50-3500
      Chloride                               2-59          2-183
      Silicon dioxide                        4-120         5-21
      Potassium                           0.11-57       0.18-90
    Chemical  and physical  properties
      Total  alkalinity                        0-1240       159-805
      Hardness (Ca + Mg)
      pH (units)                           6.9-7.9       6.6-7.8
      Total  dissolved solids (TDS)          711-3325       6-75-6000
      Specific conductance
        (mmhos/cm)
    Trace elements
      Arsenic                               <5-<10        <5-<10
      Beryllium                             <1            <1
      Cadmium                            <0.02-5        <0.02-1.1
      Copper                               0.5-4.2       0.5-1.4
      Lead                                 0.6-4.6         1-3.9
      Mercury                             <0.1-<0.5      <0.1-<0.5
      Molybdenum                            
-------
     The ARCO sampling program has been more extensive and comprehensive than
the programs at the other mines.   As a result, a clear picture of groundwater
quality in each aquifer has been  presented.   Wasatch water quality is highly
variable.  Water types are predominantly calcium or sodium sulfate, but two
samples were of the sodium bicarbonate type.  Roland coal seam waters have
either calcium sulfate or sodium  bicarbonate characters.   In its Final Envi-
ronmental Assessment (University  of Wyoming, 1976), ARCO states that the
waters in the eastern part of the lease are  more often of the calcium sulfate
type, and that as the waters move northwest, the character changes to sodium
bicarbonate.  ARCO speculates that exchange  mechanisms cause this change in
water type.  However, surface chemical reactions probably are not the major
contributor to the change.  The highly concentrated calcium sulfate waters are
at or near saturation, and precipitation of  these elements as gypsum is prob-
ably occurring as the water moves to the west.  ARCO has  not presented chemi-
cal data on alluvial or scoria aquifer waters.

     No groundwater quality data  were published in the Carter North Rawhide
Environmental Impact Statement (U.S. Geological  Survey,  1974b).   Four analy-
ses were published in Carter's mining plan update (1977).  Table 6-10 shows
these analyses.  Equivalent balances indicate that the ratio of cations to
anions ranges from 0.97 to 1.01.   Maximum and minimum data for selected con-
stituents are given in Table 6-10.


   TABLE 6-10.  WATER QUALITY ANALYSES OF WATER WELLS ON  THE RAWHIDE LEASE
                (Carter Oil Co.,  1977)
Sample
Chemical analyses (ppm)
Calcium
Magnesium
Sodium
Carbonate
Bicarbonate
Sulfate
Chloride
Silicon dioxide
Hardness (CaC03)
Total solids
Evaporated solids
Suspended solids
Volatile suspended solids
pH (units)
Specific conductance
(micromhos/cc)
Turbidity (JTU)
NRH-2
Roland
545
209
118
<0.1
640
1,740
74
19
2,200
3,188
3,180
8.5
<0.1
7.7
3,190
15
NRH-2
Smith
114
54
435
<0.1
1,570
100
65
10
502
1,760
1,760
<0.1
<0.1
7.7
1,920
2
Clinker
well
504
183
133
0
390
1,950
12
_
2,010
4,002
_
_
^
7.7
3,300
_
Main supply
well
7
4
124
0
354
3
12
_
34
329
_
_

8.2
480
3
                                    180

-------
    TABLE 6-11.  MINIMUM AND MAXIMUM VALUES AT CARTER OIL NORTH RAWHIDE
                 LEASE FOR WATER QUALITY PARAMETERS (coal aquifers)
                 (Carter Oil Co., 1977)
                    Constituent3
Minimum  Maximum
Silica
Calcium
Magnesium
Sodium
Bicarbonate
Carbonate
Sulfate
Chloride
Hardness as CaC03
pH Cunits)
10
7
4
118
354
0
3
12
34
7.7
19
545
209
435
1,570
0
1,740
74
2V200
8.2
                     In ppm except as shown for pH
     These data are not definitive, yet they indicate that the coal waters can
have calcium sulfate or sodium bicarbonate characters.  Clinker water is gen-
erally regarded to be of poor quality, and this feature is supported by the
Carter analysis.  Fort Union deep wells produce waters with good quality char-
acteristics.  The low TDS figure, coupled with the softness of the water, indi-
cate that the best quality water on the Carter lease can be found in deep wells.

     Chemical data for groundwater on or near the Kerr-McGee Jacobs Ranch lease
have been continuously collected since as early as 1966.  Reports included in
Kerr-McGee's Jacobs Ranch Mining Plan Update (1977) include data from samples
analyzed by Kerr-McGee and by the University of Wyoming.  Equivalent balances
on some of the analyses indicated that  cation-anion ratios ranged near 1.00.
Representative analyses are given in Tables 6-12 and 6-13.

     Some of the waters analyzed may have been composite samples from both the
Wasatch and coal aquifers.  Completion data for the KM series of wells were
not included in the Mining Plan Update (1977).  With the exception of KM-3, all
of the wells at the Jacobs Ranch mine area have calcium sulfate waters.  No
analyses were presented for alluvial or scoria wells.

     In its Mining Plan Update (1977), Kerr-McGee states that although TDS
values are high, salt tolerant crops should survive if irrigated with Jacobs
Ranch groundwater.  Sodium adsorption ratios are expectedly low, and boron con-
centrations are all less than 1 ppm.  Selenium, cadmium, and lead concentra-
tions exceed EPA drinking water standards in the following:  KM-3, 4, 5, 11, 12
wells.
                                    181

-------
               TABLE 6-12.
CHEMICAL ANALYSIS OF WATER FROM WELLS WITHIN  6 MILES OF PROPERTY  BOUNDARY
OF PROPOSED KERR-McGEE JACOBS RANCH COAL MINE (Hodson,  1971)
00
ro
Location/ constituent
Well location9
Well depth (ft)
Date of sample
Temperature (deg C)
Silica (S102)(ppm)
Total Iron (Fe)(ppm)
Calcium (Ca)(ppm)
Magnesium (MgHppm)
Sodium (Na)(ppm)
Potassium (K)(ppm)
Bicarbonate (HC03)(ppm)
Carbonate (C03)(ppm)
Sulfate (S04)(ppm)
Chloride (Cl)(ppm)
Fluoride (F)(ppm)
Nitrate (N03)(ppm)
Boron (B)(ppm)
Dissolved solids
(residue at 180° C)
Dissolved solids (sum
of constituents)
Hardness (Ca,Mg)(ppm)
Non-carbonate hardness
(ppm)
Specific conductance
(mmhos )
pH (units)
•BVW^^WH«^^^BI^^^_^^_^_
Fort Union
42N069W07BAC 1
120
07-08-68
_
7.7
0.550
32
17
161
7.8
370
13
185
4.4
0.4
0.9
50
610

613

149
—

951

8.4
^^^^^^^^^^M^fliMfltfMHHHMaaM
Formation
43N069W19AB 1
170
08-07-68
11.0
5.6
0.490
61
30
385
9.2
300
16
828
4.0
0.6
0.3
10
1450

1490

276
—

2080

8.5
•MHBflVMl^MM^MMMlaM^^^^^^^^^^BllpB
42N070W05DDD 1
233
07-09-68
12.0
37
1.300
414
919
720
6.8
254
0
5940
35
1.0
0.2
60
8620

8200

4810
-

7660

8.1
Wasatch
43N070U11DA 1
455
08-07-68
11.0
28.0
0.030
244
66
83
18
227
0
885
2.8
0.9
1.6
-
1450

1440

880
-

1720

8.1
• ••••III ^^^~^ . ^••••^•••^•^^^^^M
Formation
44N070W28CBC 1
261
08-07-68
11.0
8.9
0.440
40
9.7
221
5.2
345
10
306
13
1.0
0.2
10
792

785

140
-

1180

8.5
_. 	 — -
44N071W100D 1
124
07-08-68
11.0
14
0.030
299
110
74
7.0
242
0
1080
5.8
0.4
1.9
60
1860

1710

1200
-

2040

7.9
              aWell location, 42N069W07BAC 1  = Township 42 North; Range 69 West; section  F; quarter, quarter,
               quarter section BAC respectively.

-------
TABLE 6-13.   LABORATORY ANALYSIS OF WATER FROM STOCK AND DOMESTIC WELLS
             DRILLED PRIOR TO GRANTING OF LEASE TO KERR-McGEE
             (Kerr-McGee Coal Corp., 1977)
Location/date/
constituent
Location
Section
T (N)
R (w)
Date sampled
Constituents (ppm)
pH (units)
Temp (° C)
TDS
TSS
Hardness (CaC03)
Elect. Cond. (mmhos)
Ca
Mg
Na
K
As
B
Pb
Si
Zn
Mn
Ni
Cr
Cd
Hg
Cu
Fe (total)
C03
HC03
S04
Cl
N03
F

KM
NE, SE
11
43
70
8-7-68

8.1
11.0
1440
-
880
1720
244
66
83
18
-
0.570
0.570
28
-
_
_
_
-
-
-
0.030
0
227
885
2.8
1.6
0.9

#11
SE, NW
19
43
69
8-7-68

8.5
11.0
1490
-
276
2080
61
30
385
9.2
-
0.010
0.010
5.6
-
-
-
*•
-
-
-
0.490
16
300
828
4.0
0.3
0.6
Well
KM #4
SE
33
44
70
2-?-75

7.3
-
4072
5
1410
-
-
-
-
0.005
0.04
0.04
-
0.4
0.3
0.04
0.04
0.01
0.001
0.04
0.1
-
-
-
_
-
-

KM #9
SE
32
44
70
2-?-75

7.4
-
1152
n
360
-
-
-
-
0.005
0.1
0.03
-
0.6
0.09
0.1
0.01
0.003
0.001
0.06
0.6
—
-
-
-
-
M

KM #1
NE
29
44
70
2-7-75

7.7
••
460
86
90
-
-
-
-
0.005
0.01
0.005
-
0.05
0.01
0.005
0.001
0.001
0.001
0.05
0.05

-
-
-
-
-
                                 183

-------
      TEMPO  monitoring efforts will be aided by the water quality samples
 that have been  analyzed  at Jacobs Ranch.  Information on well-drilling tech-
 niques,  well  completions, and sampling and analytical procedures will aid  in
 evaluating  the  usefulness of the previously collected data.

     . Although Sun  Oil Cordero has been shipping coal since March 1977, its
 groundwater monitoring program  is not well developed.   In the Cordero Mining
 Co.  Mining  Plan Update (1976),  officials  indicated the  existence of only four
 groundwater quality monitoring  wells.  These  include three water wells and
 one  stock well.  All are Wasatch Formation wells.  Groundwater quality values
 for  these wells are shown on Tables 6-14  and  6-15.

      Cordero  reported that these samples  show stable values, and that they are
 usable data.  However, the stock well sample was not a pumped sample, and no
 field sampling  techniques were  discussed.  Also, the Hayden well is less than
 1,000 feet  from a  major  tributary to the  Belle Fourche River.  The low quantity
 of dissolved  solids in this water is probably due to hydraulic connection with
 low  TDS  surface water.

      Cordero  has reportedly designed a new monitoring plan (Tim Richmond,
 Cordero  Mining  Co.,  oral  communication, 1977).  This plan is not yet avail-
 able, but when  it  is acquired,  further analysis can be undertaken.

      In  the Wyodak Resource Development Corp. Mining Plan Update (1977), chem-
 ical  analyses of water obtained from four wells on the lease were presented.
 Two  of the  wells are located near the ash pit, one was at a coal completion
 monitoring  well  near the southern end of  Wyodak1s property, and the fourth
 well  supplies domestic water from deep Fort Union aquifers.  Analytical prob-
 lems  are indicated by cation-anion ratios which ranged from 0.75 to 5.5 for
 the  analyses  presented.  Table  6-16 presents maximum and minimum values of
 dissolved constituents in Wyodak water.

      These  sparse  data presented by Wyodak allow little interpretation.  The
 analyses are  consistent  with regional trends, in that the shallow waters are
 soft  and potable.   Background quality monitoring must be undertaken near pollu-
 tion  source areas  so that future aquifer  degradations can be recognized.

 MUNICIPAL

 City  of  Gillette Existing Groundwater Quality

     The City of Gillette uses  water from the Wasatch Formation, the Fort  Union
 Formation,  and  the Fox Hills Formation.   The Wasatch wells are considered  hard
water wells,  and the Fort Union wells soft water wells.  The Fox Hills waters
are of marginal  quality,  with high TDS, hi.gh fluoride concentrations, and  some
associated hydrogen sulfide gas being the problem parameters.  The waters  from
all  three systems  are blended to produce  a potable municipal supply.  Tables
6-17 and 6-18 summarize analyses of the City wells, as  performed by Nelson et
al.  (1976).

-------
TABLE 6-14.   GROUNDWATER QUALITY,  HAYDEN RESIDENCE,  SUN  OIL
             CORDERO LEASE (Cordero Mining Co.,  1976)
^ 	 L— — j— -L" •-,----• — 	 — -— — - T- - - -- — j in : j im nnij M» wimp ii an T— i i ••••^••••iiim«iiail*»iir-|— ; -MI 	 n — •wvnmirji — rr 	 -i _ - 	 _m _L_I 	 	 _--LT._ - _ _-jn- - -_•_•-•-••- j- mTiui TT — i 	 mrmaimwi^a^a^aMan-^MI
Date
Constituent (ppra)
Total dissolved solids
Suspended solids
Hardness
Bicarbonate-as HC03
Carbonate-as CCu
Sulfate
Chloride
Nitrate
Fluoride
Sodium
Calcium
Iron
Lithium
Arsenic
Selenium
Boron
Zinc
Mercury
Cadmium
Copper
Lead
Chromium
Molybdenum
Nickel
Aluminum
pH-field (units)
-lab (units)
Alkalinity as CaC03
Sep 3, 1974 Nov 25, 1974
328 360
6
44 45
385 377
<1 0
<5 3
7 9
1.5 2.9
1.5 1.0
118 133
10
0.24
0.01
<0.01
0.011
0.11
0.14
<0.5
<5
-
-
-
-
-
-
-
7.9 7.8
309
Feb 9, 1975
390
-
47
403
0
<1
10
1.6
1.9
150
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7.58
8.1
—
May 22, 1975
354
-
85
506
0
4
18
1.5
1.1
122
-
0.05
0.04
0.00
0.00
0.00
0.03
0.000
0
0.00
0.00
0.00
0.00
0.00
0.0
-
-
-
                            185

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  TABLE 6-15.  GROUNDWATER QUALITY, WELL NUMBER 11, SUN OIL
               CORDERO LEASE (Cordero Mining Co., 1976)
Constituent (ppm)
Total dissolved solids
Hardness
Bicarbonate-as HC03
-as CaC03
Carbonate-as C03
-as CaC03
Sulfate
Chloride
Nitrate
Fluoride
Sodium
Calcium
Iron
Lithium
Arsenic
Selenium
Boron
Zinc
Mercury
Cadmium
Copper
Lead
Chromium
Molybdenum
Nickel
Aluminum
pH-field (units)
-lab (units)
Alkalinity as CaC03

Nov 25, 1974
(a)
(a)
412
0
900
8
13.2
0.58
415
56
0.028
-
-
-
0.14
-
-
-
-
-
-
-
-
*»
-
8.1
337
Date
Feb 9, 1975
2000
920
770
0
910
12
0.90
0.53
440
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7.6
7.9
—

May 22, 1975
2160
925
1010
0
959
19
0.7
0.48
321
-
0.03
0.10
0.00
0.00
0.01
0.00
0.000
0.00
0.00
0.00
0.00
0.00
0.04
0.00
-
-
-
aSample not sufficient to  analyze.
                           186

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TABLE 6-16.   MINIMUM AND MAXIMUM VALUES FOR WYODAK MINE WATER QUALITY
             PARAMETERS3 (Wyodak Resource Development Corp.,  1977)

Constituent5
Calcium
Magnesium
Sodium
Potassium
Bicarbonate
Carbonate
Sulfate
Chloride
Nitrate
TDS
pH (units)
Minimum
179
47
220
7
163
0
110
2
0
1714
7.3
Maximum
599
327
330
33
396
6
3825
110
2.7
4652
8.5
           aBased on only four samples available.
            Expressed in ppm except for pH.
                                 187

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                      TABLE 6-17.   WATER QUALITY ANALYSIS SUMMARY  (Nelson et  al., 1976)
Source
Lance
Fox Hills
Well
No. 2
Wasatch
UP! i
nc I I
No. 17
Fort
Union
_^ Well
oo No. 6
oo
Pre-
treatment
plant
product
E.D.
1 .
plant
product
City tap
water
Arsenic
allowable
0.05

NDa
(0.01)


NO
(0.01)

ND
(0.01)



ND
(0.01)

ND
(0.01)
ND
(0.01)
Barium
allowable
1.0

ND
(0.05)


ND
(0.05)

ND
(0.05)



ND
(0.05)

ND
(0.05)
ND
(0.05)
Cadmium
allowable
0.01

ND
(0.01)


ND
(0.01)

ND
(0.01)



ND
(0.01)

ND
(0.01)
ND
(0.01)
Chromium
allowable
0.05

ND
(0.01)


ND
(0.01)

ND
(0.01)



ND
(0.01)

ND
(0.01)
ND
(0.01)
Lead
allowable
0.05

ND
(0.


ND
(0.

ND
(o.



ND
(0.

ND
(o.
ND
(0.


05)



05)


05)




05)


05)

05)
Ni trate
Mercury as (N) Selenium
allowable allowable allowable
0.002 10.0 0.01

ND
(0.001)


ND
(0.001)

ND
(0.001)



ND
(0.001)

ND
(0.001)
ND
(0.001)

ND
0.98 (0.


ND
0.19 (0.

ND
0.11 (0.



ND
0.94 (0.

ND
0.23 (0.
ND
0.93 (0.


01)



01)


01)




01)


01)

01)
Silver
allowable
0.05

ND
(0.01)


ND
(0.01)

ND
(0.01)



ND
(0.01)

ND
(0.01)
ND
(0.01)
Fluoride
allowable
(1.8)


11.2


ND
(0.1)


1.4




3.9


1.0

2.6
aND = Not detected at level indicated;  Example  = ND(O.Ol) = Not detected at level of 0.01  (ppm)
Note:  Allowable limits indicated are mandatory as set by National  interim primary drinking water regulations.

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                    TABLE 6-18.
oo
WATER QUALITY  ANALYSIS SUMMARY-GILLETTE,  WYOMING,  WATER SUPPLY,  1976
(Nelson  et  al.,  1976)
Source
Fox Hills
No. 1
Fox Hills
No. 2
Fox Hills
No. 3
H-l
H-7
H-8
H-10
H-12
H-13
H-14
H-15
H-16
H-17
H-18
H-19
H-20
H-21
H-22
H-23
H-24
H-25
H-26
H-27
S-2
SH-3
S-4
S-5
S-6
S-7
City water
at tap
Calculated
composite
hard water
Sampled
composite
hard water
gpm

56

210

340
41
41

48
56
82
52
82
52
96
56
59
41
56
41
37
82
74
85
59
65
83
65
75
50
55


1560




K

6

4

5
7
10

7
14
18

12
13
14

11
8
14


17
15
11
7
6
9
7
5
6
5
9

9.5


8

Ca

40

trace

3
161
321

321
291
602

552
432
502

402
221
462


552
562
311
341
6
462
20
15
15
15
131

305


216

Mg

24

trace

trace
82
188

148
127
182

255
145
170

248
18
170


194
200
109
145
2
94
30
12
12
6
70

158


103

so4

256

8

2
412
910

1320
1200
1920

2050
1300
1650

1620
460
1550


1920
2050
1150
1250
3
1180
10
12
8
8
565

920


668

Cl

64

56

36
16
170

28
8
16

24
36
28

44
44
16


20
20
12
28
12
16
28
16
16
20
32

36


44

Na

483

489

358
108
18

144
34
72

58
89
90

69
333
72


114
95
117
52
119
14
142
102
132
105
164

220


122

CO 3

1098

1074

903
647
537

390
98
500

488
586
500

537
1000
476


512
354
342
281
329
403
537
342
427
317
427

666


586

IDS

1414

1146

849
1105
1881

2160
1722
3056

3191
2304
2700

2658
1577
2518


3069
3116
1878
1961
310
1973
501
330
399
315
1181

1888


1450

Nad

1063

919

647
829
1479

1545
1213
2137

2285
1647
1909

1957
1131
1784


2162
2184
1321
1402
237
1365
406
260
312
246
867

1369


1077

PH

7.8

8.2

8.1
7.1
7.4

7.3
6.9
7.7

7.1
7.4
7.4

7.4
8.0
7.4


7.6
7.7
7.6
7.3
7.3
7.3
7.5
7.5
7.5
7.5
7.8

7.7


7.5

Conduc-
tivity

1960

1700

1242
—
2000

—
—
2810

2775
2225
2350

2625
2083
2450


2950
2985
2000
1925
435
2060
775
476
585
410
1550

1793


1950

Hardness
CaC03

199

trace

7.50
740
1574

1410
1248
2250

2425
1674
1951

2022
625
1851


2174
2224
1224
1447
23.0
1539
174
87
87
62
615

1248


963

Alka-
linity
CaCOs

901

981

740
_
441

.
-
410

400
480
410

440
820
415


420
290
280
231
270
331
441
281
350
260
350

589


481

                    Notes:  1.  All figures are in ppm with the exception of pH and conductivity.  Conductivity is in mmhos/cm^.
                           2.  TDS = Total dissolved solids.
                           3.  NaCl = Salt equivalent of TDS.                                                        COMPOSITE «
                           4.  Calculated composite hard water includes weighted contribution  from all hard water wells.
                           5.  Sampled composite hard water represents a sample taken from raw water tank.                    [i:'ti(GPHri)(PRQPERTYn)l
                           6.  Soft water well  waters bypass raw water tank and flow directly  into city water system.                 z'nfGPM)

-------
     The Wasatch waters (prefix H) are generally nonpotable.   Extremely high
sulfate concentrations make these waters particularly undesirable.   Some
hydrogen sulfide gas is associated with the Wasatch waters.  IDS values range
from 830 to 2,300 ppm, pH values range from 6.9 to 8.0, and the Wasatch
waters are virtually all of the calcium sulfate type.

     The City of Gillette has no wells which draw water from fractured coal
seams.  Therefore, the contribution from shallow aquifers, as defined in this
study, is the hard water Wasatch wells.  Table 6-18 also includes data from
Fox Hills and deep Fort Union wells (prefix S).  The deep Fort Union wells
yield the best product in the project area.  These high-quality sodium bicar-
bonate waters are being developed more extensively as the City of Gillette
expands it drilling program.
                                   190

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                                  SECTION  7

                            INFILTRATION POTENTIAL
     A necessary step in estimating the impact of the pollutants associated
with the various potential sources is to determine the volume of water leaving
the source and passing through the vadose zone into the zone of saturation.
This volume will vary with the method of waste disposal used, e.g., disposal
at the land surface, burial in the vadose zone, or burial below the water table,
and the infiltration  characteristics of the soil.

     Based on the limited  source monitoring currently being carried out in
the project area collectively by the mines, the City of Gillette, and various
State and Federal agencies, only exemplary estimates of infiltration potential
for a few select sources can be made.  These sources fall under three major
categories:  coal strip mining, coal conversion, and municipal.
                                                     ;
COAL STRIP MINING

     Sufficient information is available in the project area to provide some
estimate of the infiltration potential of pit discharge and spoils materials.

Pit Discharge (Active Mining Area Source)

     As discussed previously in Section 2 (Potential Sources of Pollution and
Methods of Disposal), the primary methods of disposal of pit discharge and
their hydrologic source classifications are:

     t  Dust control -  diffuse

     •  Irrigation of reclaimed spoils -  diffuse

     •  Discharge to surface water and subsequent percolation -  line.

     In the case of discharge to surface water, holding ponds are commonly
used to retain the pit discharge prior to release.  These holding ponds thus
comprise a potential point source of groundwater pollution.

     Pit discharge is used for dust control primarily in the months when precipi-
tation is low and the land surface is relatively dry.  This water is applied to
haul  roads in the pit,  haul roads between the pit and the coal storage silos,
and to other unpaved roads around the plant.  Such roads are commonly built on
natural  soil  or disturbed overburden, and sometimes on the coal itself in the
pit.   Most of this water is applied during periods of maximum potential

                                    191

-------
evapotranspiration.  The surfaces to which the water is applied are relatively
compacted due to heavy equipment traffic.  Thus, virtually none of the applied
water would be expected to infiltrate and percolate beneath the surficial
materials, but would largely be lost to evapotranspiration.  However, pollu-
tant constituents  in the applied water are largely retained in the surficial
materials.  These  constituents could later be leached to groundwater as a
result of excessive watering of the roads or as a result of rainfall causing
runoff to carry the potential pollutants into the ditches.

     The infiltration potential of pit discharge used for  irrigation of reclaim-
ed spoils is discussed under Spoils (Reclaimed Area Source).

     The primary method of disposal of pit discharge in the winter, when use of
water for dust control is minimal or unnecessary, is to streams near the mines.
This water usually mixes with other surface water which is present in the winter.
As streamflow, there is potential for percolation, particularly in areas down-
gradient from the  mines.  Streamflow can percolate to aquifers whose water
 levels are below the channel bottom.  This is a potential  line source of pollu-
tion  in  the  hydrologic context and may be from several to  tens of miles long,
depending on the streamflow and infiltration characteristics.  Since much pit
discharge water is disposed of in winter months when evapotranspiration rates
are low, less opportunity exists for disposal by evapotranspiration.

     Holding ponds for pit discharge may overlie native materials, such as
alluvium beneath a floodplain, or disturbed materials such as spoils.  The
amount of infiltration depends to a large extent on the permeability of the
underlying materials.  In general, the future locations of holding ponds and
the underlying materials are poorly known for most mines and, thus, their
infiltration potential is also poorly known.  Better knowledge could be gained
by the careful measurement of flow volumes for pit discharge and the disposi-
tion of  pit discharge.  This, in combination with knowledge of precipitation
and evapotranspiration rates, would allow water budget calculations to deter-
mine wastewater loading and infiltration for each method of disposal.

Spoils (Reclaimed  Area Source)

     Four primary  sources of water may eventually contact  the spoils.  These
sources  can be grouped into point, line, and diffuse in the hydrologic context.
The sources are:

     §   Precipitation or applied irrigation water -  diffuse

     t   Streamflow -  line

     t   Ponded water above spoils -  point

     t  Groundwater -  diffuse.

     Little precipitation is expected to percolate past the topsoil due  to  the
relatively high potential  evapotranspiration rates as compared to  the  precipi-
tation  rate.   As  discussed under the modified hydrogeology portion of  Section
5  (Hydrogeologic  Framework), the presence of free lime in  undisturbed  soils


                                   192

-------
suggests that under natural conditions little or no precipitation infiltrates
past the topsoil.

     The spoils will be dressed with topsoil or equivalent.  Parts of the
spoils will contain a high percentage of broken and pulverized shale that
decomposes rapidly.  Such spoils will generally have a high clay content and
are expected to have low permeability.  Other parts of the spoils will contain
broken and pulverized sandstone and alluvium and may be more permeable.  The
structure of the soil used for surface dressing will be destroyed in handling
and this material will generally have a higher infiltration capacity than the
underlying spoils.

     However, after settlement, the surface dressing will probably have a
lower infiltration capacity than the natural soils.  Thus, it is unlikely
that infiltrating water from precipitation will percolate past the topsoil on
areas other than those that receive surface runoff.

     Water availability will be a limiting factor in irrigating spoils during
the first several years of reclamation.  The relatively low aquifer transmis-
sivities and well yields limit large scale water applications for irrigation.
However, there is some potential for downward percolation of return flow from
irrigation, depending on the amount of water applied compared to the evapo-
transpiration.  Measurement of water application will enable estimates to bp
made of potential infiltration by the water budget method.

     Many mining plans call for removal of coal beneath present-day flood-
plains.  During mining, the stream is temporarily diverted around the active
pit.  After mining, when the spoils are in place, the streams are to be
reestablished to simulate natural  conditions.  In this situation, spoils mate-
rials will be returned in place of natural alluvium beneath the stream
channels.  Geomorphic processes will then act to reestablish a hydraulic
equilibrium.  For example, alluvium may be carried into the area from up-
gradient lands, or some spoils.  This will depend on the permeability of the
spoils and top dressing, the possible presence of organic deposits in the
channel infiltration, and the turbidity of the flowing water.  Although the
spoils will probably have a lower infiltration capacity than the alluvium,
seepage from streamflow could be a major source of water coming into contact
with the spoils.  In this case, water available for infiltration depends on
streamflow.  The amount of infiltration through the channel bottom depends
not only on the subsurface materials, but on the hydraulic head distribution.
If groundwater levels are higher than the channel bottom, little or no infil-
tration will occur.  Present data indicate that the natural channels in and
near the mine leases are both gaining and losing, depending on the area and
reach of the stream.  The same situation may also prevail after the alluvium
is removed.

     If water is temporarily ponded above spoils, then a point source of
groundwater pollution may result from leaching.  In this case, the amount of
water available for infiltration can greatly exceed the evapotranspiration
rate.  If groundwater levels are of sufficient depth, then percolation of
the water past the topsoil can readily occur.  The infiltration rate will
depend on permeability of the spoils, the amount of organic deposits in the


                                   193

-------
pond bottom due to biologic activity, and turbidity and temperature of the
stored water.  This particular source would probably be of limited duration
for holding ponds, but if large bodies of standing water are formed on the
dressed spoils due to topographic conditions, a source of long-term duration
could be established.

     In the case of groundwater migrating laterally through the spoils, the
topsoil and vadose zone are bypassed, and there is no need to discuss infil-
tration potential from the land surface.

COAL CONVERSION

 Potential  Pollution Sources

     Of the  three important types of coal conversion anticipated to be imple-
mented  in  the project area -  steam electric, gasification, and liquification -
 only  steam electric currently is operating at a level where significant impacts
 are expected.

 Steam  Electric Power Plant -

     The existing and planned power plants at Wyodak will generate wastes from
a number of  sources.  Presently, fly ash and some other wastes are discharged
 to a slurry  pond  in the North Pit.  Future plans call for disposal of virtually
all wastes from the power plant in the two pits at the Wyodak mine.  The wastes
 to be disposed of are fly ash as solid fill in the pits, and liquids and other
wastes  in  a  pond  in the North Pit.

     Fly ash  in the solid form could be emplaced at any depth in the pit.  This
disposal method is similar to that for spoils, in that some material could be
considerably  above groundwater, but still be subject to leaching.

     A  number of types of liquid wastes, including sewage effluent, apparently
will be disposed of in the existing pond in the North Pit and may constitute'
an abundant source of water for leaching.  Although an extensive clay bed report-
edly underlies the coal at Wyodak, the infiltration potential of wastes from
this pond  is  poorly known.  A water budget analysis could be made if the volume
of flow and solid fly ash were known.

MUNICIPAL  SOURCES

     The City of Gillette is the principal municipality in the project area.
Three primary potential sources of groundwater pollution are associated with
the City:  the landfill, the sewage treatment plant, and the water  treatment
plant.   A matter of regional concern is the potential impact of the coal  strip
mining on the City's water-well field.  Currently, only limited information  is
available on  the first three potential sources, and insufficient  information is
available to discuss the impact of mining on the well field.

Landfill
     Sources located at the landfill site include:  a metal  disposal  area, oil

                                    194

-------
waste disposal area, dead animal pit, garbage trenches, oily waste and septic
tank pumpage sites, tire disposal area, and a covered dump.  Except for the
garbage trenches,(these pits and disposal areas terminate within overburden
overlying a shallow coal seam.  The garbage trench is constructed within the
coal bed.

Metal Disposal Area -

     The metal disposal area serves as a repository of refrigerators, old cars,
metal drums, other discarded metals, and tires.  These solid wastes are dis-
carded on the land surface.  Consequently, infiltration occurs across the
indigenous soil surface.  Infiltration is probably optimal because of the mini-
mal disturbance of the soil surface.

Oily Waste Disposal Area -

     Wastes disposed of in this area include primarily petroleum byproducts,
and possibly some hazardous substances.  Infiltration may be inhibited by the
movement of sludge sediment and fines into the pores and cracks of the over-
burden.  In addition, certain organic fluids may preclude capillary uptake.

Dead Animal Pit -

     Infiltration beneath the dead animal pit is probably similar to that for
undisturbed materials, except possibly for slight clogging by organics.

Garbage Disposal Site -

     The garbage disposal trench infiltrates into the fractured coal seam.  The
surface of the seam may be disturbed by the operation of heavy equipment,
impeding intake rates.  Surface runoff into the trench may carry down fine
sediments which would also tend to seal off the surface.  The penetration of
landfill leachate with high concentrations of calcium and sulfate might lead to
the formation of gypsum deposits within seam fractures, again reducing infil-
tration.  Precipitation of limonite [Fe(OH)2] would have a similar effect.  The
degree of infiltration reduction by these mechanisms may depend greatly on the
size of fracture openings.

Pits for Oily Waste and Septic Tank Pumpage -

     Infiltration characteristics are similar to those of the oily wastes dis-
posed of in the same area and may restrict infiltration.

Covered Dump -

     Surface infiltration into the covered dump may be similar to that for
native material.  Movement of pollutants from the base of the dump into the
native vadose zone is governed, to some extent, by processes similar to those
discussed for the active landfill.
                                    195

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Sewage Treatment Plant

     Potential sources of groundwater contamination associated with waste-
water treatment in Gillette include:  (1) treatment plant facilities; (2) an
oxidation pond; (3) a sludge disposal pond; and (4) Donkey Creek.

Treatment Plant Facilities-

     Treatment plant facilities include aeration, secondary clarifiers, and
aerobic digestion tanks.

     Discussion with wastewater management officials for the City indicate
that the aeration, clarifier, and digestion tanks may leak directly into the
shallow groundwater system at the plant site.  No data are available, however,
on  the magnitude of seepage.

Oxidation Pond—

     Wastewater entering the "oxidation" pond probably has received minimal
treatment in  the wastewater treatment plant.  Additional treatment in the
pond probably occurs under anaerobic rather than aerobic conditions.

     Infiltration from the pond may be minimal because of the penetration of
benthic materials into the pores of the underlying soils -  an effect observ-
ed  in established ponds (Deming, 1963).  An exact value will necessitate a
water balance study (Todd et a!., 1976).

Sludge Disposal Pond-

     The infiltration potential of the sludge pond will be restricted by the
movement of organics and fine sediments into the pores underlying vadose zone
materials.  In fact, the infiltration rate may be essentially zero.

Donkey Creek—

     Wastewater discharged from the oxidation pond enters Donkey Creek,
essentially a line source of potential groundwater contamination.  The qual-
ity of wastewater will change somewhat during flow in the creek.  For
example, nitrates may increase because of aeration due to algal activity,
wind action, etc.   In addition, periodic discharge events resulting from
flash floods or snowmelt may dilute pollutants.

     Infiltration into the Donkey Creek streambed will generally decrease
over time because of clogging of the channel deposits with organics and
fines.   However, periodic discharge events may scour the channel and tempo-
rarily increase intake rates.  In addition to infiltration, another factor
to consider is the consumption of water from the vadose zone  by  riparian
vegetation along the channel.  The amount of recharge  into  the saturated
zone will  consequently be reduced during the growing season of such vege-
tation.   Evapotranspirative losses may also occur directly  from  the shal-
low groundwater system.
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Water Treatment Plant

     Water treatment facilities for the City of Gillette include a degasifier,
a raw water storage tank, a lime softening plant, and an electrodialysis plant
(Nelson et al., 1976).  Wastewater from the lime softening plant and electro-
dialysis plant is discharged directly into the Stone Pile Creek or into a
nearby hand-dug brine disposal well.  Most of the wastewater goes into Stone
Pile Creek.  The disposal well is filled with filter sand and occasionally
refilled as it subsides.

     Brine from the electrodialysis plant probably contains excessively high
concentrations of major chemical constituents together with trace contami-
nants.  Organics and microorganisms probably are not present in significant
quantities.  Sulfate is the principal contaminant in wastewater from the lime
softening process.

     Wastewater discharged into the disposal well probably bypasses the
entire vadose zone and enters directly into a shallow aquifer.  "Infiltra-
tion," thus, refers to seepage of wastes out of the well into the aquifer.
In effect, the well functions as a type of recharge well.  Intake rates of
such wells are affected mainly by entrained air, sediment, precipitation of
salts, and microbial activity.  Intake rates in the brine disposal well are
probably affected by sediment, salt precipitation, and entrained air.

     Infiltration of wastewater in Stone Pile Creek may be decreased by the
precipitation of salt in the stream channel; by clogging resulting from
microbial activity; or by sedimentation.  Periodic discharge events in the
Creek from snowmelt or flash floods may scour the channel and improve intake
rates.  Some water loss may occur in the channel and underlying alluvium by
evapotranspiration.  Such losses may increase salt concentration of infil-
trating wastewater.
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                                  SECTION 8

                     POLLUTANT MOBILITY IN THE VADOSE ZONE


      This  section discusses the movement of pollutants which have infiltrated
 the vadose zone.  The pollution sources discussed fall under the major cate-
 gories of  coal  strip mining, coal conversion, and municipal.

 COAL STRIP MINING

      The primary methods of disposing of strip mining pit discharge water are
 to use the water for dust control on mining roads during the dry season, dis-
 charging surplus water  to streambeds during the wet season, and using the water
 for irrigation  of reclaimed spoils.  Pollutant mobility of water infiltrating
 into the vadose zone from these uses is discussed in this subsection in terms
 of water movement and pollutant transport and attenuation mechanisms.

 Pit Discharge (Active Mining Area Source)

      When  using pit  discharge water for dust control, the amount applied is not
 sufficient to mobilize  any pollutants in the water downward from the surface.
 However, road wetting in a pit can result in pollutants that remain at the
 bottom of  the pit or are later emplaced in subsurface spoils, enhancing their
 potential  for groundwater pollution.  The pollutants will be comprised of those
 that are indigenous  to  the native groundwater plus any added by mining opera-
 tions.

      Discharge  of pit water to the surface will usually be to an alluvial
 channel  where the vadose zone is typically very thin.  In some future situa-
 tions, the discharge could be to a stream overlying spoils in a reclaimed area.
 Shallow groundwater  levels may prevent percolation in the channel of stream-
 flow,  or mixing with other surface water may attenuate pollutants substantially
 before reaching a point downstream where percolation or evapotranspiration does
 occur.   Such  a  determination can be made only by accurate measurement of the
 rate of  waste discharge and the rate of flow upstream and downstream from the
 discharge  point.

     Pollutant-attenuation mechanisms in the chemical sense are poorly  known
 because  the lithology of the alluvium has not been adequately established.
 Little pollutant attenuation may occur in sandy areas, while substantial pollu-
 tant attenuation may occur in clay areas.  Some pollutants could be removed
from the discharge area by streamflow that does not percolate and become con-
centrated downstream.  Alternatively, the pollutants could migrate downward
near the point of discharge and concentrate in local aquifers.


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Spoils (Reclaimed Area Source)

     Several sources of water may enter the vadose zone In the spoils.  These
include return flow of water used for irrigation during reclamation of spoils,
streamflow percolation in former floodplain areas, and seepage from holding
ponds constructed on the spoils.

     Mann (1976) discusses hydrologic interactions for wastewater in the vadose
zone of arid regions.  The vertical distribution of materials comprising spoils
will affect downward movement of water in the vadose zone.  Poor topsoils, dis-
turbed overburden, waste coal, shale interlayers, buried refuse, and other
materials will be somewhat haphazardly emplaced as spoils.  Perching layers may
be formed and result in saturated conditions and lateral movement of percolat-
ing water in the vadose zone.  Under present conditions, water flow in the
vadose zone is apparently largely through fractured consolidated rocks.  Because
the spoils are largely comprised of broken up rocks, the modified flow may be
through a medium more similar to granular, porous media and this unconsolidated
material will be more subject to leaching as water passes through it.  Virtually
nothing is presently known about the hydrologic characteristics of the existing
natural vadose zones or those that will exist after the spoils are emplaced.
However, the characteristic depth to water is likely to be 100 to 200 feet.

     Little excess irrigation water is expected to percolate past the topsoil
during reclamation.  However, the volume of applied water can be measured to
determine potential percolation past the topsoils, and the water budget can be
calculated to determine if the water application, hydrologic characteristics of
the spoils and dressing material, and climatic factors at a given location
appear to result in a net excess.

     Leaching potential from streamflow percolation may be substantial in the
former floodplain areas after emplacement of spoils.  Accurate measurements of
flow at stream-gaging stations along certain reaches of these areas can be used
to determine seepage losses.  Depending upon the water table depth, virtually
all of the water passing through a stream channel could be absorbed.  However,
groundwater beneath the floodplains could be ultimately consumed by evapotrans-
piration.  Perching layers above the water table could result in horizontal
movement of the recharged water some distance away from the stream channel.

     Substantial  volumes of water may seep from holding ponds constructed on
spoils to the water table.  Perching layers above the water table may spread
recharge water horizontally and increase the impacted groundwater area beyond
that of the surface source.

     Although slightly different combinations of pollutants may be introduced
by the different sources of water, vadose zone pollutants derived from spoils
will  be similar regardless of the source of water.  Most of the additional
pollutants that will  be in pit discharge water used for irrigation are covered
by the parameters of concern for the spoils.  Thus the following discussion
generally applies to all  three sources of water applied to the spoils.  Poten-
tial  pollutants include inorganic chemical, organic chemical, and radiological
types.
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Potential Mining and Reclamation Pollutants

     Major inorganic chemical  groundwater pollutant constituents that can
enter the vadose zone are calcium, magnesium, sodium, potassium, carbonates,
chlorides, sulfates, boron,  fluorides,  iron,  manganese, nitrogen oxides, and
phosphorous oxides.   Inorganic chemical  trace elements are barium, chromium,
copper, lead, lithium, nickel, strontium, vanadium, zinc, zirconium, arsenic,
cobalt, cadmium, mercury, beryllium,  selenium, molybdenum, titanium, bromine,
tin, tellurium, and  silver.   Organic  chemical compounds (total  organic carbon,
or TOC) can also migrate through the  vadose zone,  as can the radiological com-
pounds of uranium, thorium,  and radium-226.

     Runnels (1976)  discusses  the geochemical interactions of wastewater in
the vadose zones of  arid regions.

     The bacteriological content of water leaving  the vadose zone should be low
due to pollutant attenuation in the topsoil  and vadose zone.

     Of the major inorganic  chemical  constituents, sodium and chloride are rela-
tively mobile.  Calcium, magnesium, bicarbonate, and sulfate may be precipitat-
ed out in the vadose zone.  However,  these and other constituents may be
dissolved from minerals by water percolating  through the vadose zone.  Nitrate
is relatively mobile and iron and manganese are generally immobile under
aerobic conditions.

     At least three  major sources of  data can be used to assess trace element
mobility in the vadose zone.  First,  numerous leaching studies  have been per-
formed for specific  elements applied  to  specific soils.  Second, the general
geochemical behavior for many  trace elements  in natural water systems is fairly
well defined.  Third, the occurrence  of  selected trace elements in groundwater
is generally known.

     Keeney and Wildung (1977) summarize soil interactions with trace metals.
Fuller (1977) presents a detailed discussion  of trace element mobility in soils.
He states that numerous factors control  pollutant  mobility, but in general the
following are most significant:

     •  Soil  texture or particle size

     •  Pore space distribution in the soil

     •  Content and  distribution of iron, aluminum, and manganese
        oxides  and hydroxides  in the  soil

     •  pH  of the  soil  and percolating waters

     •   Oxidation-reduction  potential in the  soil

    •  Organic  matter  content of soils  and percolating waters

    •  Concentration of trace elements.
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     Selenium was found to be relatively mobile under aerobic conditions such
as might be present in the vadose zone.  Iron, zinc, lead, copper, and beryl-
lium were moderately mobile.  Arsenic, cadmium, chromium, and mercury were
slowly mobile.

     Hem (1970) discusses the occurrence of a number of trace elements in natu-
ral waters.  Beryllium is generally not present in dissolved form in such waters
because of its low solubility.  Strontium contents are greatly limited by sul-
fate contents as high as those in the groundwater of the Gillette area.  Barium
can also be  adsorbed  by metal  oxides  or hydroxides  and  thus  generally occurs  in
only small  concentrations  in groundwater.   Titanium is  not present in high con-
centrations  in natural  water because  of the low solubility of its  oxides  and
hydroxides.   Vanadium appears  to  be soluble in groundwater under anaerobic con-
ditions and  may be present in  significant  concentrations  if  a source  is present.

     Numerous instances of chromium contamination of groundwater have been
documented. The anionic species are apparently relatively stable in many ground-
water  systems.  Molybdenum is predominantly present in the anionic form in
groundwater.  There appears to be no effective solubility control  over molybde-
num concentrations and thus large values may be found if a source is present.
Cobalt content in groundwater is likely controlled by manganese or iron oxides
and hydroxides and generally is low in groundwater.  The general  geochemical
behavior of nickel is similar to that of cobalt.

     The solubility of cupric oxide and hydroxy-carbonate minerals tends to
limit  the content of copper in groundwater to low values.  Silver content is
limited by the solubility of silver oxide and silver chloride.  In dilute
aerated water the equilibrium concentration of silver should be less than 0.01
 ppm.   Concentrations of zinc exceeding  1  ppm  can be in groundwater.  Cadmium
 contents in groundwater are generally  very  low; however,  some cases  of
 cadmium contamination  have  been documented  for  groundwater.  Very few  natural
 waters contain detectable concentrations  of mercury.

     Lead content is controlled by bicarbonate and sulfate contents.  Lead
sulfate is relatively insoluble, particularly in aerobic situations.  Arsenic
can be present in the anionic form over the pH range of most natural waters.
Numerous occurrences of arsenic in groundwater under anaerobic conditions have
been documented.  The sorption of arsenate on ferric hydroxide or other active
surfaces is likely an important factor limiting arsenic contents in natural
waters.  The stable form of selenium in aerobic groundwater is the anion form
but little information is available on selenite solubility.   Bromide has a geo-
chemical behavior similar to chloride, and thus can occur in relatively high
contents in groundwater.

     Groundwater quality studies throughout the U.S. indicate that the trace
elements chromium, vanadium, arsenic, cadmium, selenium, molybdenum, and bromine
have been found in high concentrations in certain hydrogeologic situations.   All
of these elements readily form anions in the soil-groundwater system and may be
mobile in the vadose zone.   Studies of hazardous waste disposal  summarized by
the U.S. Environmental  Protection Agency (1976c)indicate that the results of
soil-leaching studies are consistent with these observations.  These consti-
tuents should thus be given priority over other trace elements in a monitoring
program.
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      Organic chemicals may move with percolating water through the vadose zone.
 However, the organic chemicals to be expected in water that contacts materials
 such as coaly wastes have not been well defined.  Leenheer and Huffman (1976)
 have proposed a classification scheme for organic solute characterization.  The
 scheme begins with dissolved organic carbon and is further divided on the basis
 of solute sorption and acid-base characteristics.   Little is known about the
 mobility of the organic chemical fraction of wastes that comprise the spoils.

 COAL CONVERSION

 Anticipated Conversion Mechanisms

      Of the three important types of coal  conversion anticipated to be imple-
 mented in the project area -  steam electric, gasification, and liquification—
 only steam electric currently is operating at a level  where significant  impacts
 are expected.

 Steam Electric Power Plants

      Water disposal at the Wyodak power plant consists of solid fly ash land-
 filled in the pits and fly ash slurry which is disposed of in  a pond.

      Pollutant mobility in the vadose zone for fly ash disposed of above  the
 water table is somewhat similar, in the hydrologic sense,  to that for spoils.
 The cases of primary concern would be point or line sources superimposed  on  the
 buried fly ash.   At Wyodak this could be percolation of Donkey Creek streamflow
 after spoils and fly ash are emplaced.   Also,  holding  or* storage ponds could
 permit large amounts of percolation in  local  areas.  Little is known about the
 hydrologic characteristics of a vadose  zone comprised  of landfilled fly ash.

      For the fly ash slurry pond in the North Pit, the introduction of sub-
 stantial amounts of water is planned, and  this can be  an important source of
 water for leaching materials in the slurry pond to the water table.

      For fly ash,  major potential  inorganic chemical pollutants include calcium,
 magnesium,  sodium,  potassium,  carbonates,  chlorides, sulfates, boron,  fluorides,
 iron,  manganese,  nitrogen oxides,  and phosphorus oxides.   Trace elements  in-
 clude  vanadium,  nickel,  copper,  zinc, arsenic,  selenium,  lead, antimony,  tita-
 nium,  rubidium,  strontium,  barium,  cadmium,  cobalt,  chromium,  molybdenum,
 cesium,  bromine,  silver,  tungsten,  iodine,  mercury,  lithium, zirconium, beryl-
 lium, and  tellurium.   Radiological  pollutants  are  uranium,  thorium, and radium.

     The discussion  on  pollutant attenuation  in the  vadose  zone for spoils is
 generally applicable to fly  ash.  However,  in  fly  ash,  the  concentrations of
 some trace metals are particularly  high and  are of concern.  Vanadium,  molybde-
 num, and cadmium occur  in high concentration and are possibly  mobile.   Arsenic,
 selenium, bromine, and  iodine should  receive priority  for monitoring of waters
contacting fly ash.  The major constituents, total dissolved solids, fluorine,
and boron should also receive priority.
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 MUNICIPAL
      The three major municipal  pollution sources are the Gillette landfill,
 sewage  treatment plant,  and water treatment plant.

 Landfill
      For  convenience,  the mobility of pollutants  underlying  the  following areas
 are  treated  together:   (1) metal  disposal  area  and the  tire  disposal area;  (2)
 oily waste disposal  areas and  the septic  tank pumpage area;  (3)  the dead animal
 pit; and  (4)  the  garbage  disposal  area.

 Metal  Disposal  Area  and Tire Disposal  Area -

      Potential  pollutants in the  metal disposal area may  consist of trace con-
 taminants from  metals; organics in hazardous waste containers; freons, and
 possibly  microorganisms.   Pollutants  in the tire  disposal  area may consist  pri-
 marily of oily  wastes, since tires are relatively stable.

      The  vadose zone underlying the metal  disposal  and  tire  disposal areas  is
 undefined at this time.   However,  extrapolating from the  profile exposed in the
 garbage trenches, it appears that the soil  profile is relatively thin and under-
 lain by bedrock sandstones or  shales.  In  turn, overburden may merge at a
 shallow depth with a coal  seam.   Water movement in both the  overburden and  coal
 occurs primarily  through  fractures.   Depth to water table is unknown.  Because
 the  landfill  is located on a knoll, however, it would appear that water levels
 may  be fairly deep,  perhaps as much as 100 to 200 feet.

      Mobility of  trace contaminants through the relatively thin  soil profile
 may  be governed primarily by the  factors  listed by Korte  et  al.  (1977) as soil
 texture,  surface  area, percentage  of  free  oxides,  and pH.  The figures of
 Korte et  al.  (1977), reproduced as  Figures  8-1 and  8-2,  will  be used to estimate
 the  mobility  of trace elements.   Assuming  also  that the soils at the disposal
 site are  similar  to  Mohave sandy  loam, the mobilities of  copper  and lead will
 be low; and beryllium, zinc, cadmium,  nickel, and  mercury mobilities will be
 moderate.  Similarly, the mobilities  of selenium,  vanadium,  arsenic, and
 chromium  may  be high in the landfill  soils.

      Movement of  trace contaminants in the shale  or sandstone overburden may
 occur primarily through cracks  and  fissures.  The  interactions of contaminants
 with the  solid  matrix may not  be  as significant as those  occurring during flow
 through the soil.  It is  known, for example, that salts are  more readily leach-
 ed through a  well-structured soil  by  unsaturated  rather than saturated flow
 (Biggar and Nielsen, 1967).  Iron-oxide coatings  have been observed in over-
 burden  samples  from  the mine sites.   If such deposits occur  in the landfill,
 overburden trace  contaminants  may  become  sorbed (Keeney and  Wildung, 1977).

     Because of insufficient data, it  is not possible to quantitatively
describe the movement and attenuation of trace contaminants  in the coal seam.
However, trace metals may accumulate ;at the interface between overburden and
coal  by some undefined process.  Drever et  al.  (1977),  for example, noted
such  an accumulation of trace metals in a coal-overburden  interface on the


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Black Thunder mine.  The presence of partings above the coal with low pH
values suggests that the mobilities of cationic metals may have been augment-
ed in this region.

     Movement of trace metals in the coal seam will occur through fractures.
Again, data are not available to permit the prediction of metal attenuation.

     Movement of organics may be moderated by the following mechanisms:  sorp-
tion, lowering of the pH into the acid range, and microbial decomposition.
Sorption may be a factor in the soil profile, but may be insignificant in the
remainder of the vadose zone.  The action of microorganisms may be of primary
importance in attenuating organics from the source.  Details are discussed
below in the section on oily wastes.

     Movement of pesticides from containers scattered throughout the area is
difficult to predict without soils data.  Davidson et al.  (1976) point out
that "...pesticide movement through the soil and into the groundwater may be
increased significantly owing to adsorption-desorption characteristics of a
pesticide at high concentrations."  Davidson et al.  (1976)  used the  Freundlich
equation to characterize pesticide mobility in a silty clay loam soil.

     Movement of microorganisms in the vadose zone underlying the metal disposal
and tire areas may be restricted primarily by sorption and  filtration with the
shallow soil profile.  Further movement into the underlying fractured bedrock
may not be inhibited by those effects.  The presence of pesticides at waste or
container concentrations may reduce or stop the activity of otherwise viable
soil microorganisms  (Davidson et al.,  1976).

Oily Waste Disposal Areas and Septic Tank Pumpage Area -

     Oily wastes probably consist of spent petroleum substances such as lubri-
cants, transmission fluid, as well as additives, and some hazardous wastes.
Because of decomposition of organics, inorganics tend to concentrate.  Trace
contaminants may also accumulate.

     The disposal pits for these areas appear to be constructed in bedrock.
Consequently, the ameliorating effects of the soil profile  on pollutant mobility
may be minimal.

     Because surface reactions of pollutants within bedrock cracks and fissures
are probably minimal, the mobility of macro-constituents within the  vadose  zone
may be restricted primarily by precipitation reactions.  For example, calcium
carbonate and calcium sulfate may precipitate.  Precipitated gypsum  is evident
in the coal  seam within the garbage trench.  Similarly, precipitates of limonite
[Fe(OH)2] may occur.   Precipitates may clog fractures to the point that infil-
tration will  be inhibited-thus  restricting  mobility.   Because of anaerobic
conditions within the pits, nitrogen will tend to remain in the organic or
ammonium forms.   Leakage of wastes into the vadose zone, however, may expose
these  nitrogenous forms to sufficient oxygen to permit nitrification to take
place.   Nitrates will  then flow farther into the vadose region.

    Mobility of trace  contaminants (e.g., lead in oily waste) may  be  affected


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                             Pb   I   Be   I   Zn   I   Cd   I   Ni
        j	l^^^/^^^>C^^v>^X\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\Ni


Figure 8-1.   Mobility of copper,  lead, beryllium,  zinc,  cadmium, nickel,
              and mercury through  10 soils series  (from Korte et al.,
              1977).
 Figure 8-2.   Mobility of  selenium, vanadium,  arsenic, and chromium
               through 10 soils  series (from  Korte et al., 1977).
                                    205

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by the presence of organic acids within the oily waste and septic disposal
ponds.  Lowering the pH tends to increase the mobility of cationic heavy metals.
Reducing conditions will  also favor the mobility of such constituents as arse-
nic, beryllium, chromium, copper, iron, and zinc (Fuller, 1977).  The presence
of sulfides, however, will act to precipitate FeS, ZnS, CdS, PbS, CuS, Hg2$,
and HgS.  However, sulfate reduction to sulfide is restricted at lower pH
values and mobilities of trace contaminants may not be too inhibited by the
formation of precipitates.

      Organics  in oily wastes and septic tank pumpage will be subjected to micro-
bial  decomposition.  The rate of decomposition may be fairly slow, however,
because of anaerobic conditions in the pit and because of the chemical complex-
ity of the waste.  According to Grove (1975):  "...buried oily waste will remain
unchanged for  hundreds of years."  Streng (1976), however, notes microbial
decomposition  of refinery sludge, buried with domestic solid waste, by the
evolution of carbon dioxide and methane gases.  Both gases are evolved under
anaerobic conditions.

      The subsurface movement of microorganisms is a particular problem in the
septic  tank pumpage sites.  Because filtration and sorption mechanisms afforded
by  the  soil will be bypassed, microorganisms flow directly into cracks and
fissures.   If  these cracks are fine enough, some filtration may be affected.
However, attenuation will occur primarily by effects such as pH, temperature,
and salt content on the  viability of microorganisms.

Dead  Animal Pit -

      The dead  animal pit also appears to be excavated into bedrock.  However,
dead  animals are covered with crushed overburden.  Principal contaminants with-
in the dead animal pit are principally organics and pathogenic organisms.
Mobility of these constituents will be governed by the same mechanisms for the
oily  wastes and septic tank pumpage areas.  In addition, the crushed overburden
may afford a certain degree of filtration of organics and bacteria.

Garbage Disposal Area -

      Domestic  and commercial solid wastes generated in the Gillette area are
disposed of in the garbage trenches at the landfill site.  The trenches may
be as much as 33 feet deep and are excavated through the overburden into the
coal  seam.  Leachate production in the solid wastes buried in the landfill  is
favored by surface runoff into the trenches and by groundwater seepage through
the coal seams.

     Pohland and Engelbrecht (1976) provide the following useful description
of leachate:

               Sanitary landfill leachate is very likely to have a
          very high concentration of both organic and inorganic con-
          stituents,  including heavy metals; accordingly, the concen-
          tration of total dissolved solids will be high.  The pH of
          leachate is most often in the acidic range.  However, the
          exact nature of leachate will depend upon such factors as

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          the composition of the solid wastes placed in the landfill
          and the degree of chemical and biological activity.  These
          factors, along with residence time or the age of the
          material in the landfill, largely influence the chemical
          and physical characteristics of leachate.  The presence of
          pathogenic or infectious agents will be a function of:
          (1) the density and nature of the pathogens placed in a
          landfill; (2) the ability of the pathogens to survive or
          to retain their infectivity in the landfill environment or
          the leachate; and (3) the ability of the pathogens to move
          through the landfill with the leachate into the surrounding
          environment.  Because of  its chemical, physical and/or
          biological properties, leachate can potentially impair the
          surrounding environment,  i.e., nearby surface water or
          groundwater.

     Because leachate will move from the base of the landfill trenches into a
 fractured rather than porous matrix, attenuating mechanisms, such as those
 associated with soils, may be minimal.  In fact, internal modifications within
 the landfill may be more important  in attenuating pollutants.  Such modifi-
 cations are described by Pohland and Engelbrecht (1976).  Internal modification
 of leachate will occur via undefined physical-chemical reactions among liquid,
 solid, and gaseous phases.  "Chemical changes occurring may involve oxidation-
 reduction reactions, coagulation, and acid-base reactions, while physical
 changes may result from filtration, ion exchange, sorption and precipitation."
 As a result of such reactions, solid wastes will become stabilized and the
 quality of leachate will change.  The concentration of organic matter and phys-
 ical and chemical constituents will gradually decrease.

     Leachate initially contains excessive concentrations of the major chemical
 constituents, calcium, magnesium, sodium, potassium, sulfate, and bicarbonate.
 The mobilities of certain of these constituents are controlled to some extent
 by microbial activity within the landfill.  In particular, biological stabili-
 zation of organics results in carbon dioxide (C02) production and leads to the
 formation of carbonic acid.  The pH of leachate is reduced into the acid range.
 The solubility of calcium carbonate is increased by carbon dioxide production
 and a lowered pH so that the mobilities of calcium and bicarbonate ions will be
 augmented.  Eventually, however, the pH may be increased in the vadose zone
 flow system such that calcium carbonate will precipitate.  High concentrations
 of sulfate observed in runoff water within the garbage trench suggest that
 precipitation of gypsum may occur within the coal seam.  Both calcium and sul-
 fate would then be removed from the flow system.

     The solubility of magnesium carbonate is also influenced by the presence
 of carbon dioxide and free movement within the vadose zone would be expected.
 Similarly, sodium and potassium salts are soluble unless concentrations are
 increased to several thousand parts per million.  Mobilities of these salts
 will probably be slight.

     The anaerobic environment within the landfill will prohibit nitrification
of organic and ammonium nitrogen.  However, both nitrogen and ammonium nitrogen
may move to some extent into the coal seam.  Sorption of ammonium nitrogen will


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 be  minimal  because clays are  not  present.   If  sufficient oxygen  becomes avail-
 able  in  the flow  system, nitrification of ammonium  nitrogen may  eventually
 occur.

      The mobility of trace elements  in the  vadose zone  will be of particular
 concern  in  the  initial  leachate.  At that time,  carbon  dioxide evolution by
 microorganisms  will be  at a maximum,  resulting in the production of carbonic
 acid.  Organic  acids will also  be abundant.  As  pointed out above,  the  mobili-
 ties  of  cationic  metals are enhanced in lower  pH ranges.   Similarly, if  reducing
 conditions  are  obtained, the  mobility of the following  trace  contaminants will
 be  increased:   arsenic, beryllium, chromium, copper, cyanide, iron, and zinc
 (Fuller, 1977).   Organic acids may also favor  the production of  organic  complex-
 es  with  trace contaminants, increasing their mobilities.   In contrast to these
 mechanisms  favoring the mobility of  trace metals, precipitation  of  certain
 metals will occur in the presence of sulfides, including FeS, ZnS,  CdS,  PbS,
 CuS,  Hg2S and HgS.  In  order  for such sulfides to form, however,  it will  be
 necessary for the pH to increase into a range  favorable to sulfur-reducing
 microorganisms.

      The mobility of organics in landfill leachate will  probably not be  inhibit-
 ed  by sorption.   The relatively high TDS of leachate, however, may  favor the
 flux  of  organics  (Metcalf and Eddy,  1975).  Possibly the principal  mechanism for
 retarding the movement  of organics will be microbial stabilization.  A  secondary
 effect may  be that some organics may  precipitate in low pH leachate.  Leenheer
 and Huffman (1976) note the formation of an organic precipitate  upon acidifica-
 tion  of  a groundwater sample  for an  oil shale  area in Wyoming.

      Regarding  microorganisms, Pohland and Engelbrecht  (1976) indicate:   "...a
 significant reduction in the  population of microorganisms can be expected with
 time...  The decrease in density of biological  indicators of fecal pollution
 would  indicate  that leachate would not likely  show many, if any,  pathogenic
 microorganisms.   Examination of leachate for enteric viruses has confirmed  this;
 further, it has been demonstrated that leachate, because of certain of  its
 chemical  constituents,  has the capacity to inactivate pathogenic bacteria and
 enteric  viruses... As a consequence,  the chemical and physical characteristics
 of  leachate are probably potentially more significant in terms of impact on  the
 surrounding environment than  its biological properties."

      From the above it  appears that  the leachate initially flowing  into the
 vadose zone will  mainly contribute microorganisms.  Again, because  of the
 limited  capability of the coal seam  to filter  and sorb  organisms, mobility  may
 be  relatively unrestricted.  Some sedimentation of bacteria may  occur and
 environmental conditions may be conducive to die-off.   Viruses,  however, would
 probably flow for a considerable distance.

 Sewage Treatment  Plant

     Section 7 discusses the infiltration potential of  several potential sources
of groundwater pollution.   The following discussions generalize  on  the  mecha-
nisms  which  govern the mobility of the pollutants entering the vadose zone.
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Treatment Plant Facilities -

     Lack of field data precludes an exact definition of the nature and extent
of the vadose zone at the plant site.  Also, if the supposition of City of
Gillette officials is correct, the vadose zone may be completely bypassed dur-
ing leakage of pollutants from the tanks.  As a first estimate, therefore,
attenuation of these pollutants in the vadose zone is minimal.

Oxidation Pond -

     The factors and constituents discussed below will greatly influence the
mobility of pollutants carried by seepage from the oxidation pond.

     Macroconstituents -  The principal macroconstituents in lagoon seepage
will be similar to those discussed previously for leakage from the wastewater
tanks:  calcium, sodium, phosphate, sulfate, bicarbonate, and nitrogen.  Reac-
tions will be similar except as moderated by aerobic conditions within the
unsaturated flow regime.  Calcium will tend to form precipitates with bicar-
bonate and sulfate and compete with sodium for exchange sites on clay and
organic surfaces.  Phosphate mobility is strongly restricted because of inter-
action with carbonates, hydrous oxides, and silicate minerals (Keeney and
Wildung, 1977).

     In the anaerobic environment of the "oxidation" pond, organic nitrogen may
be mineralized to ammonia but nitrification will be inhibited.  Migration of
ammonia into the vadose zone may be restricted because of sorption on the
organics within the benthos.  Further below the benthos-soil interface, ammonia
may become fixed on clay mineral surfaces or become involved in exchange reac-
tions.  If oxygen levels are sufficiently high in the unsaturated media and if
a source of organic food supply is available, nitrification may occur.  How-
ever, because of the shallow depth to the water table at the pond site, it is
difficult to predict the extent of nitrification.

     Trace pollutants -  The possibility of polluting the groundwater beneath
the lagoon at Gillette with heavy metals was pointed out previously in the
discussion above on trace pollutants.  For example, Lund et al.  (1976) observ-
ed heavy metals in soil solution extracts 10 feet below the base of effluent
ponds constructed in coarse textured soils.  Metal concentrations in the infil-
tration  from the pond will be lower, however, than the corresponding levels
in infiltration from the sludge pond, because sludges accumulate heavy metals.
Levels of zinc may be particularly high (Ms. Paddock, Supervisor, water and
wastewater plants, City of Gillette, personal communication).

     Fuller (1977) listed the following 10 general factors as important in
migration of heavy metals in soils:  hydrogen ion activity (pH), oxidation
reduction, particle size distribution of soils (surface area), pore size dis-
tribution, lime, organic matter, concentration of ions or salts, certain
hydrous oxides, climate (weathering), and aerobic and anaerobic conditions.
In controlled laboratory experiments, Korte et al.  (1977) found that  the
following soil  properties were dominant in influencing trace pollutant mobil-
ity:   soil texture and surface area, percentage of free oxides, and pH.
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     As a first estimate of the mobility of heavy metals in the vadose zone
underlying the pond,  the figures developed by Korte et al  (1977) on the
relative mobility of cations in the seven most prominent soil  orders in the
U S. are utilized.  These figures are reproduced as Figures 8-1 and 8-2.
Characteristics of the soils used in the study by Korte et al. (1977) are
reproduced in Table 8-1.  Comparing soils in Table 8-1 with soils in the
Gillette area, it appears that of the soils evaluated by Korte (Figures 8-1
and 8-2), the Mohave sandy loam is the most comparable to the Gillette area
soils.  Figure 8-1 shows that copper and lead have low mobilities; beryllium,
zinc, cadmium, nickel, and mercury have moderate mobilities.  Similarly,
Figure 8-2 shows that the following metals have high mobility:  selenium,
vanadium, arsenic, and chromium.
                                                                     i ^
      Regarding the mobility of zinc, Fuller (1977) indicates that Zn   forms
slowly  soluble precipitates with carbonate, sulfides, silicate, and phosphate
ions.   (The  presence of sulfide in water seeping from the pond is highly
likely.)

      The  mobility of  trace metals  in soils will be moderated by  the  presence
of organics.   Digestion  in anaerobic ponds leads to the formation of organic
acids,  lowering  the pH.  The mobility of cationic heavy metals  increases as
the pH  decreases.  Consequently, metals may penetrate the vadose zone  beneath
the pond  to  the  depth that organic acids are neutralized.

      Finally,  the formation of metal-organic chelates may increase  the mobility
of some trace  contaminants.

      Organic pollutants  -  The mobility of organics is affected  by  the factors
discussed under  Treatment Plant Facilities:  sorption, pH,  TDS,  and  micro-
organisms.   Of possible  relevance  to the migration of organics  beneath the pond
are results  of studies by Schaub et al.  (1975) on rapid infiltration of waste
water.   In particular, soil samples from active cells were  observed  to contain
high levels  of TOC and heavy metals in a "black asphaltic"  layer at  a  depth of
about 18  inches.

     Microorganisms - Mobility of microorganisms will be influenced by filtra-
tion, sedimentation, and sorption mechanisms.  The flux of  viruses,  in parti-
cular, will  be affected by salt concentration,adsorption, pH,  organic  matter,
and  infiltration  rates.  Quantitative data are needed to determine  the relative
effect of these mechanisms on virus movement in the vadose  zone  underlying the
Gillette pond site.

Sludge Disposal Pond -

     Factors affecting the mobility of contaminants in the  vadose zone are
essentially identical to those discussed above for the  "oxidation"  pond.
However, the levels of heavy metals will be greater because of the  tendency of
sludges to accumulate metals.   All metals are present in excessive  concentra-
tion, but the levels of lead,  copper, and zinc are particularly high.
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                          TABLE 8-1.  CHARACTERISTICS OF THE  SOILS (from  Korte et al., 1977)
ro
Soil
Wag ram
(N. Carolina)
Ava
(Illinois)
Kalkaska
(Michigan)
Davidson
(N. Carolina)
Molokai
(Hawaii)
Chalmers
(Indiana)
Nicholson
(Kentucky)
Fanno
(Arizona)
Mohave
(Arizona)
Mohave
(Arizona)
Anthony
(Arizona)
Order
Utisol
Alfisol
Spodosol
Ultisol
Oxisol
Mollisol
Alfisol
Alfisol
Aridisol
Aridisol
Entisol
CEC
pH (me/100 g)
4.2
4.5
4.7
6.2
6.2
6.6
6.7
7.0
7.3
7.8
7.8
2
19
10
9
14
26
37
33
10
12
6
EC
(vimhos/cm)
225
157
237
169
1,262
288
176
392
615
510
328
Surface
area
(m2/g)
8.0
61.5
8.9
51.3
67.3
125.6
120.5
122.1
38.3
127.5
19.8
Free
iron Total
oxides Mn Sand
(percent) (ppm) (percent)
0.6
4.0
1.8
17
23
3.1
5.6
3.7
1.7
2.5
1.8
50
360
80
4,100
7,400
330
950
280
825
770
275
88
10
91
19
23
7
3
35
52
32
71
Silt
(percent)
8
60
4
20
25
58
47
19
3/
28
14
Clay Texture
(percent) class
4
31
5
61
52
35
49
46
11
40
15
loamy sand
silty clay
loam
sand
clay
clay
silty clay
loam
silty clay
clay
sandy loam
clay loam
sandy loam
Predominant .
clay minerals
Kaolinite,
chlorite
Vermiculite,
kaolinite
Chlorite,
kaolinite
Kaolinite
Kaolinite,
gibbsite
Montmoril lonite,
vermiculite
Vermiculite
Montmorillonite,
mica
Mica, kaolinite
Mica,
montmoril lonite
Montmoril lonite,
mica
       alisted in order of importance.

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     Studies by Lund et al. (1976) demonstrated that heavy metals migrate to
depths as great as 10 feet below anaerobically digested sludge holding
ponds.  The metals examined were zinc, cadmium, copper, chromium, and nickel.
The soils were coarse textured.  The authors found that redistribution of
metals was closely related to change in COD of soil samples with depth.  Metal
movement was thus attributed to the formation of organic chelates.  Other
passible factors promoting metal migration include pH and oxidation reduction
potential.  For example, during the first stage of anaerobic digestion of
sludge, organic acid formation lowers the pH to a value of about 5.1 (Health
Education Service, nd).  The lower pH promotes the flux of cationic heavy
metals (Fuller, 1977).  Also, according to Fuller, reducing conditions in soil
promote the movement of arsenic, beryllium, chromium, copper, cyanide, iron,
and zinc, but have little effect on the movement of cadmium, lead, and mercury.

     Anaerobic conditions obviously occur in both the sludge lagoon and "oxida-
tion" pond at the Gillette wastewater treatment plant.  Because of the shallow
water table at this site, heavy metals may be introduced almost directly into
the aquifer.

 Donkey  Creek  -

      Mobility of  pollutants  in  the  vadose zone will  be affected  by mechanisms
 discussed in  detail  for treatment plant facilities,  the  "oxidation" pond, and
 the sludge  disposal  pond.  However,  the area! extent of  the  vadose  zone con-
 tacted  by the pollutants is  far greater than  for  the  essentially point sources.
 As a  result,  attenuation mechanisms  associated with  exchange,  sorption, etc.,
 are enhanced.

      Periodic flows  of snowmelt or  rainfall  runoff may dilute  or flush out  the
 vadose  zone to  some  extent.   The  exchange capacity,  or sorption  sites, may  be
 rejuvenated by  such  dilution.   However, snowmelt  may increase  the mobility  of
 viruses.   Lance et al.  (1976)  observed the  desorption and migration of viruses
 in soil  columns following application of deionized water.   Columns  were pre-
 viously  flooded with  secondary  sewage effluent.

 Water Treatment Plant

      The  hand dug disposal well essentially bypasses the vadose  zone.  Most
wastewater  is disposed  of into  Stone Pile Creek.   Wastewater infiltration
into Stone  Pile Creek will enter  the vadose  zone  as  a line  source.  The vadose
zone is probably  about  80  feet  thick in the  vicinity of  the  water treatment
plant.  No  information  is available  on the  lithology of  the  vadose  zone.
However, some floodplain  alluvium may be present  in  the  vicinity of Stone Pile
Creek.  The alluvium  probably merges with bedrock at a shallow depth.  Water
movement in the bedrock  may be  restricted primarily  to cracks  or fissures.

     Attenuation of major chemical constituents in the alluvium  may be govern-
ed to some extent by processes observed in  soils,  e.g.,  sorption and  exchange
reactions, and precipitation-solution reactions.   The high  concentrations of
salts or brine from the  electrodialysis plant may favor  the  formation of
calcium and magnesium carbonates, gypsum, and even some  sodium precipitates.
The mobility of chloride will not be affected.  The  exchange complex  of  the


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limited amount of clays in the alluvium probably would be quickly swamped.
Precipitation may similarly limit the movement of major constituents into the
fractured bedrock underlying the alluvium.

     The mobility of constituents in the lime softener wastewater will  be
greater than for the electrodialysis brine because the relatively low salt
concentrations will not favor precipitation.  Some sorption or exchange reac-
tions may occur; however, movement into the underlying bedrock will  probably
be inhibited.

     Mobility of tract constituents will be governed by such factors as pH,
reducing conditions, presence of hydrous oxides, and sorption.  If the  dis-
charge of electrodialysis brine or softening plant wastewater is fairly
continuous, anaerobic conditions will develop in a shallow subsurface zone of
the channel.  A characteristic of such a regime is that sulfate will be re-
duced to sulfide, leading to the formation of insoluble precipitates such as
iron sulfate, cadmium sulfate, zinc sulfate, lead sulfate, copper sulfate,
and mercury sulfate.  In contrast, however, reducing conditions increase the
mobility of arsenic, beryllium, chromium, copper, cyanide, iron, and zinc.
Cyanide will denitrify and evolve as a gas (Fuller, 1977).  Organic acids,
formed for example from decaying channel vegetation, may lower the pH suffi-
ciently that the mobilities of cationic trace metals will be increased.
Chelation of metals with organics will also increase mobility.
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                                   SECTION  9

                   POLLUTANT MOBILITY  IN  THE  SATURATED ZONE


      Pollutants which are conservative in nature or manage to pass through the
 various attenuation mechanisms present in the vadose zone are of concern in
 this  section.  These pollutants are still subject to the attenuating  mechanisms
 of  the saturated zone, i.e., buffering, chemical precipitation, filtering, and
 dilution.

      If upon entering the zone of saturation a pollutant becomes immobile due
 to  one of  these mechanisms, it becomes a philosophical question as to whether
 groundwater quality degradation has taken place or whether the assimilative
 capacity of the subsurface environment is being utilized.  The solution to
 this  question lies in the proximity of existing or potential usage to the depos-
 ited  pollutant.

      Pollutants which prove to be mobile in the saturated zone may eventually
 result in  damage to existing or future groundwater usage.  The concentration
 and toxicity of a particular pollutant and the proximity of a discharge point
 for usage  to the point of entry of the pollutant to the zone of saturation will
 greatly influence the threat associated with a particular source.

 COAL  STRIP MINING

      The two sources in this class which are expected to result in pollutants
 reaching the saturated zone are pit discharges disposed of in certain ways,
 and spoils.

 Pit Discharge (Active Mining Area Source)

      For pit discharge, the primary processes of concern for monitoring in the
 saturated  zone are percolation from polluted streamflow and seepage  from hold-
 ing or storage ponds.  In the case of disposal to surface water, the primary
 method of  pollutant transport is by surface water flow.  Although NPDES (Na-
 tional Pollution Discharge Elimination System) permits are required  for such
 discharges, they are designed for surface water considerations rather than
 their effect on groundwater.  In addition, the present discharge requirements
are fragmentary in nature and are not comprehensive.  Although pollutants
could be carried some distance downstream from the point of discharge,  sub-
stantial  dilution could also occur at the same time.  Rates of groundwater
movement in the alluvial  aquifers have been discussed under the following
material  on spoils.   Monitor wells should generally be placed as close  to  the
stream channel  as possible.  For percolation from holding ponds  (a point


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 source),  considerations discussed under the following discussion on spoils
 will  be applicable.   That is, flow rates in the consolidated formations  are
 generally slow and monitor wells must be located in immediate proximity  to
 the source.                                                           J

 Spoils (Reclaimed Area Source)

      Two  major types of waste disposal involving spoils can be considered:

      t  Direct emplacement of spoils below the equilibrium water
         level  (after pit dewatering is ceased)

      • Movement of liquids through the spoils to the water table.

      This latter type has been previously addressed in Section 7 (Infiltration
 Potential) and Section 8 (Mobility of Pollutants in the Vadose Zone).  Again,
 mobility  can be discussed in terms of (1) water movement, and (2)  pollutant
 transport and attenuation mechanisms.

      For  spoils directly emplaced into areas that will be below the ground-
 water level  after active mining stops, no pollutant attenuation will have pre-
 viously occurred.  As groundwater contacts the spoils, numerous pollutants
 will  directly enter the groundwater.  In situations where spoils are in  contact
 with fractured rock, such as at the bottom of former pits, pollutants may be
 directly  introduced to groundwater in fractures.  Less pollutant attenuation
 due to physical and biologic factors may occur under this circumstance than any
 other. An important factor is that the lower part of the spoils will often be
 the depository for materials with the highest pollution potential.   Examples
 are toxic soils, clay layers near the coal or interlayers, and waste coal.

      Some constituents in liquids moving through all  or part of the vadose zone
 in the spoils  will have the opportunity for substantial attenuation.  However,
 numerous  pollutants will likely be picked up by the percolating water.   The
 major important cases would be for streamflow percolation and for  seepage from
 holding or storage ponds on the spoils.

      Polluted  groundwater in the spoils  can be viewed as  a diffuse  source in
 the hydrologic sense in that,  after mining is  completed,  large  areas could be
 affected.  The rate  of movement of the polluted groundwater depends on aquifer
 transmissivity,  porosity,  and the hydraulic gradient.   Aquifers  potentially
 impacted  include shallow alluvium,  nearby downgradient coal  beds, nearby down-
 gradient  overburden,  and formations underlying the  spoils.   Surface water can
 also  be impacted because in some areas the groundwater discharges to surface
 water.

     Hydraulic characteristics  of the  spoils are poorly known and no aquifer
 tests have been  reported  for mines  near  Gillette.   However,  Rahn (1976) report-
 ed a transmissivity of 11,000 gpd per  foot and a storage  coefficient of 0.12
 for a 27-hour  pump test  on  a 33-foot  thickness of saturated spoils  at the
 Hidden Creek mine  near Sheridan,  Wyoming.   Additional  pump tests are necessary
 to adequately determine  aquifer parameters for spoils  in  the Gillette area.
Transmissivity of the  Fort  Union  and Wasatch Formations,  including  the coal


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 beds,  commonly range from several hundred to several thousand gpd per  foot.
 Based  on  present data, it appears that both the transmissivity and storage
 coefficient of spoils will generally be several times larger than those of
 the undisturbed consolidated formations.  Aquifer characteristics for  the
 alluvial  aquifers are generally unknown.

     The  hydraulic gradient to be expected in spoils is unknown.  However,
 King (1974) noted that hydraulic gradients in the more permeable aquifers of
 the Gillette  area range from 10 to 25 feet per mile.  Hydraulic gradients in
 the least permeable aquifers may exceed 100 feet per mile.  The average hy-
 draulic gradient for consolidated rock aquifers is probably about 40 to 50
 feet per  mile.  The University of Wyoming (1976) reported on the extensive
 groundwater monitoring at the ARCO Black Thunder mine.  The hydraulic  gra-
 dient  for the coal aquifer ranged from 15 to 40 feet per mile.

      Porosities for different aquifer materials are not well known.  However,
 an independent analysis of groundwater flow rate can be obtained from  the
 results of carbon-14 age dating of groundwater at the Black Thunder mine.
 Ages in the range of 11,000 to 34,000 years for groundwater within several
 miles  of  the  recharge point indicate very slow travel times, in the range of
 only several  feet per year.  Assuming a porosity of 0.10 for fractured con-
 solidated rock, a groundwater flow rate of about 35 feet per year is calcu-
 lated, based  on average values for transmissivity and hydraulic gradient.
 Flow rates of groundwater in the spoils are generally unknown.

     The  rate of groundwater flow in the consolidated rock aquifers implies
 that polluted groundwater entering these aquifers would generally move very
 slowly.   Thus monitor wells would have to be located very close to a poten-
 tial source of pollution.  It might require a thousand years for such  water
 to flow only  one-quarter of a mile.  The key conclusion is that little effect
 on groundwater quality would be noticeable over the short term except  in the
 immediate proximity of the source.  Flow rates in the alluvial aquifers
 (underflow) could be much greater; however, these are generally unknown due
 to lack of data on aquifer characteristics and hydraulic gradient.

     The  monitoring of point and line sources would necessitate having wells
 as close  to the surface as possible.  For monitoring a diffuse source, such
 as the  spoils, the wells can be constructed directly in the spoils.  Vadose
 zone monitoring and land surface monitoring can provide information on travel
 times  to  the  saturated zone and an indication of when polluted water might be
 expected  to reach the water table.

     The  chemical  aspects of pollutant transport and attenuation are not con-
 sidered further because of the relatively slow groundwater flow rates, which
 exert the  controlling factor on pollutant mobility in the saturated zone.

 COAL CONVERSION

     The one coal  conversion activity of particular importance in the  project
area is steam electric power generation.
                                    216

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Steam Electric Power Generating Plants

     At the Wyodak power plant, there are two methods of disposal to consider:
solid fly ash landfilled in the pits, and the fly ash slurry pond.  For the
solid fly ash disposal, materials may be placed below the equilibrium water
level.  Thus, such materials would be in the saturated zone after mining ceases.
Virtually no pollutant attenuation will have previously occurred.  Previous
discussions in Section 7 (Infiltration Potential) and Section 8 (Mobility of
Pollutants in the Vadose Zone) apply to solid fly ash disposed above the
equilibrium water level and to the fly ash  slurry pond.

     As groundwater enters the buried fly ash, a number of pollutants will
directly enter the groundwater.   In  situations where solid fly ash is in con-
tact with fractured rock, such as at the bottom of  the pit, pollutants may be
directly introduced to groundwater in fractures.  Less pollutant attenuation
due to physical and biologic factors may occur under this circumstance than
any other.  The solid fly ash disposal can  be viewed as a diffuse source, as
it will occur over a relatively large area.  The rate of movement of ground-
water in saturated fly ash is generally unknown.

     A number of pollutants could be picked up as water moves vertically through
the fly ash beneath the slurry pond, which  can be viewed as a point source.  For
pollutants reaching the water table, similar considerations apply as those dis-
cussed for mining spoils pollutants.  That  is, groundwater movement in the con-
solidated rock aquifers is generally slow and monitor wells would have to be
placed in immediate proximity to  the pond.

MUNICIPAL SOURCES

     All three sources discussed  previously in Sections 7 and 8 also have poten-
tial for the production of pollutants which are likely to be mobile in the zone
of saturation and thus may result in groundwater quality degradation.

Landfill
     Relatively little information  is available on the groundwater system
beneath the landfill.  According to a regional potentiometric surface map pre-
sented by Keefer and Hadley  (1976), groundwater movement probably occurs in a
northerly direction beneath  the site.  Consequently, pollutants moving into
the groundwater flow system  will move as a plume towards the City of Gillette
well field.  Because of slow velocities, however, the effect may not be notice-
able for a considerable time.

     Dilution may occur in the flow system, but, again, data are insufficient
at this time to facilitate predictions, for example, by flow net analyses.

     An extensive scoria deposit appears to underlie the northeastern region of
the landfill site.  Field observations suggest that this scoria deposit is
highly permeable.  For example, when the water tank above the landfill was
drained onto the land surface recently, it was noted that the water infiltrated
rapidly.   Within a day, water was observed to bubble out at the base of the pit
(courtesy Ms. Paddock).  This observation suggests that snowmelt or runoff water

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 may flow  into  the scoria and possibly into the underlying shallow aquifer
 system.   Dilution of a leachate plume would subsequently result.

 Sewage Treatment Plant

       Again, because of the lack of data, mechanisms for attenuating pollu-
 tants in  the saturated zone can be speculated upon only qualitatively at this
 time. As pointed out by Todd et al . (1976), similar mechanisms may be opera-
 tive in both the vadose zone and saturated zone.  In addition, a pollutant
 plume in  the saturated region will be moderated by dilution with native ground-
 water.

 Treatment Plant Facilities  -

      For  convenience, potential treatment plant pollutants will be categorized
 as:  macroinorganic,  trace  elements, organics, and microorganisms.   It will also
 be assumed that the shallow aquifer system is within floodplain alluvium, so
 that flow occurs  in a porous matrix, rather than through fractures.

      Macroconstituents - Based on estimated wastewater quality for  the  City
 of Gillette (see  Section 3, Table 3-18), it appears that the  principal macro-
 constituents  include calcium, sodium, sulfate, bicarbonate, phosphate, and
 nitrogen.  Chemical controls on the mobility of calcium are reviewed by Hem
 (1970),  including  the tendency of calcium to precipitate with bicarbonate and
 sulfate.

      For  the flow  system beneath the treatment plant,  it may  be possible to use
 a method  developed  by Hem (1970), Back and Hanshaw (1965), and Bower et  al .
 (1965) to determine the tendency of CaC03 to precipitate.  In addition to pre-
 cipitation, calcium mobility may be limited by exchange reactions on clays.
 For this  case, calcium will be in competition with sodium for exchange sites.
 The relative degree of sodium adsorption on clays is described by the sodium
 adsorption ratio, SAR:

                  SAR = Na+ /[(Ca++ + Mg++)/2]1/2
      Sulfate and  bicarbonate mobilities are linked to reactions  with  calcium
 and magn'esium.   In  addition, sulfate may be sorbed to a minor  extent  on the
 aquifer matrix  and  be  retained  by hydrous oxides of  iron  (Keeney and  Wildung,
 1977).   The  latter  reactions, however, require low pH values.  The presence
 of organic acids  in tank  seepage may have a local effect  in  reducing  pH and
 consequently on sulfate mobility.

      Phosphate  retention  and mobilities are discussed by  Keeney  and Wildung
 (1977).   In  acid  soil, phosphorus is sorbed on the surface of Fe- and Al-
 containinq minerals to form surface compounds.  As pointed out above, organic
 acids presentin tank leakage may have a local effect  on lowering  pH values and
 consequently promote the  above  reaction.  However, eventually, organic acids
 will be neutralized  in the  predominantly alkaline groundwater  system.  For
 alkaline conditions, sorption of P on CaCOs or formation  of  Ca phosphate miner-
als may occur (Keeney and Wildung, 1977).  Phosphate retention on clays and
hydrous oxides may also be  important in the saturated flow system.

                                      218

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     Nitrogen mobility in  the saturated system will  involve only the  organic-N
 and NH4-N forms.  That is,  nitrification will  be inhibited in  the anaerobic
 environment.  Organic-N may be removed by filtration or become involved  in
 metal complexation  reactions.  Mobility of the ammonia  form will  be restricted
 primarily by exchange  reactions on clay surfaces.

     Trace pollutants  - The flux of trace pollutants (i.e., heavy metals and
 trace metals) from  the wastewater tanks will  probably be markedly reduced
 because of the  tendency of  sludge to concentrate such metals.   The metals enter-
 ing the groundwater system will be affected by reactions in anaerobic systems.
 At the outset,  it should be noted that the mobility  of  trace metals is greater
 in anaerobic than aerobic  systems (Fuller, 1977).  Thus, "Reducing conditions
 in soil promote mobility of most of the trace  contaminants.  Cadmium, lead,
 and mercury mobility may be little affected by the lack of oxygen  as compared
 with As, Be, Cr, Cu, Cn, Fe,  and Zn, which will  migrate at a greater rate"
 (Fuller, 1977).  If sulfides  are present,  however, anaerobic conditions may
 lead to the formation  of relatively insoluble  compounds such as  FeS, ZnS, CdS,
 PbS, CuS, HggS, and HgS.  The presence of  organic acids also affects the mobil-
 ity of trace contaminants  because cationic metals are mobile in  the lower pH
 ranges.  However, the  flux  of arsenic, selenium, and cyanide will  not be
 appreciably affected.   Organic acids may also  favor  the production of organic
 complexes with  trace contaminants increasing their mobility.

     The mobility of trace  contaminants will be moderated also  by  exchange with
 clays and organic matter and adsorption reactions with  hydrous  oxides of Fe and
 Al.

     Organics - High  COD,  TOC, and BOD values are undoubtedly  present in tank
 seepage.  Specifying the mobility of organics  is difficult because quantitative
 studies have only recently  been reported.   One problem  is that  analytical proce-
 dures to identify organics  are still being developed.   Research  is needed to
 improve capabilities to analyze samples comprehensively so that  significance of
 trace organics  in the  environment can be determined  (Donaldson,  1977).  Recent-
 ly, Leenheer and Huffman (1976) described  the  development of the dissolved
 organic carbon  (DOC) technique for fractionating organics into  hydrophobic and
 hydrophilic components using  macroreticular resins.   The technique was applied
 to several natural  waters.   This technique has advantages over other methods,
 such as activated carbon,  for concentrating organics.  For example, Robertson
 et al. (1974) reported that only 10 percent of organics present in ground-
 water beneath a landfill in Oklahoma were identified using carbon adsorption
 followed by carbon  chloroform and carbon alcohol extraction.

     Because of the limited information on attenuation  of organics in a porous
 medium, only qualitative estimates of mobility can be presented  at this time.

      Sorption  may be an important factor  in attenuation.  It is known,  for
example,  that PCB's  tend to be  strongly adsorbed by soil and are also  insoluble
in water  (Robertson  et al., 1974).   Leenheer and Huffman  (1976) indicate that
both  hydrophobic and hydrophilic organics may be sorbed  by sediment.

     Leenheer and Huffman (1976)  noted the formation of an organic precipitate
 upon acidification  of  a groundwater  sample from an oil  shale area  near Rock


                                      219

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 Springs, Wyoming.  Raising the pH dissolved the precipitate.  Possibly,  in a
 localized situation, organic acids may lower the pH sufficiently that precipi-
 tation may be a factor.  However, neutralization of acids would preclude pre-
 cipitation of organics.

      The relatively high IDS of wastewater may affect the mobility of organ-
 ics.  For example, in leaching studies on spent shale using a high IDS "foul
 water," Metcalf and Eddy (1975) observed about 55 percent reduction in organ-
 ics  expressed as TOC.

      Finally, microorganisms may effect a removal of organics, for example,
 by the formation of methane, carbon dioxide, and other gases.

      Microorganisms -  Microorganisms entering groundwater from the tanks in-
 clude fecal  coliform, fecal strep, virus, amoeboid cysts, intestinal worm eggs,
 and  parasitic fungi.  The cysts, eggs, and fungi will be removed by filtration.
 Bacteria may be attenuated near the interface with the aquifer by filtration,
 sedimentation, and adsorption.  Migration of virus may be moderated by adsorp-
 tion rates  (Gilbert  et  al.,  1976).   Studies by  Schaub et al.  (1975) on  virus
 mobility in  coarse soils of high-rate infiltration cells, indicated that
 viruses are  capable of bypassing filtration and sorption mechanisms and pene-
 trating groundwater.  In fact, viruses were observed to migrate horizontally
 more than 600 feet from the source.  Migration of viruses may occur in a
 similar fashion away from the tanks.

      Dilution effects -  The effects discussed above for attenuating the,inor-
 ganic, organic, and microbiological sources will be supplemented by dilution
 in the water-bearing formation.  The magnitude of dilution will require field
 data (currently not available) on volume of wastewater entering the water
 table, waste loading, areal hydraulic head distribution, transmissivity of the
 aquifer, vertical and horizontal hydraulic conductivity values, quantity and
 quality of recharge from other surfaces, and pumpage in the area (Todd  et al.,
 1976).

 Oxidation Pond -

      The mechanisms of transport for pollutants from this source are similar
 to those discussed above for treatment plant facilities.

 Sludge Disposal  Pond -

      The mechanisms of transport for pollutants from this source are also simi-
 lar to those discussed above for treatment plant facilities.

 Donkey Creek -

     Mechanisms  for attenuating pollutants in the shallow saturated region
will  be  similar to those discussed above for treatment plant facilities.
However,  dilution effects may be magnified because of the larger surface
area  of  the aquifer contacted by percolating wastewater.  Also, periodic
flows of  snowmelt and thunderstorm discharge will enhance dilution.


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Water Treatment Plant

     Definitive information is not available on the hydraulic properties of the
aquifer which receives recharge from the brine disposal well or from Stone Pile
Creek.  The potentiometric water surface is also unknown.  Consequently, it is
not possible to develop flow nets to estimate dilution of pollutants at this
time.  Mechanisms operating in the vadose  zone may also contribute to attenua-
tion of pollutants but, again, data are not available.

      The  regional  potentiometric  map  of  the  aquifer  system  in  the Gillette
 area by  Keefer  and  Hadley (1976)  shows that groundwater moves in  a northerly
 direction.  As  a  consequence,  recharged electrodialysis brine or  softening
 plant wastewater  will  flow toward  the  City of Gillette well  field, which is
 a relatively  short  distance away.
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                                SECTION 10

        PRIORITY  RANKING OF POTENTIAL GROUNDWATER POLLUTION SOURCES


     Three major classifications of potential pollution sources have been
 inventoried,  Agricultural,  Industrial, and Municipal.  The principal thrust
 of  this  inventory has been to review the existing information and data to
 determine what is known about the potential impact of the sources within
 these major classes on groundwater quality, and then make a preliminary
 (Level  One) ranking based on this information.

 AGRICULTURAL ACTIVITIES

     Agricultural  activities  in the project area were inventoried for poten-
 tial groundwater pollution sources.  These sources were found to be  insigni-
 ficant  due to their diffuse nature.  Irrigated farmland is practically non-
 existent and dryland farming is the general method.  Most farming in the area
 is  economically marginal.  Cattle ranching is the primary agricultural acti-
 vity-   On the mine leases funds may become available which could result in
 reclamation activities which approach  intensive agricultural activities.  This
 could result in  the presence of potential agricultural-related groundwater
 pollution sources such as leaching of  inorganic nitrogen from mine spoils by
 irrigation waters used to establish vegetative cover, and from feedlots.

     Based on the above observation,agricultural activities currently will
 require  only limited surveillance, e.g., through aerial photography.

 INDUSTRIAL

     The Industrial classification includes Construction, Oil and Gas Extrac-
 tion, Coal Strip Mining, and Coal Conversion activities.  Of these four, coal
 strip mining and coal conversion are apparently the most significant in terms
 of  potential groundwater quality degradation.

 Construction

     During the course of the potential pollution source inventory,  it was
 observed that almost all of the wastes associated with the construction
 industry are either disposed of in the Gillette landfill, and as a result
 come under the Municipal wastes category, or are disposed of with mine  solid
wastes on the leases.  The same can be said for sanitary wastes from the
construction industry where the City or mine disposal facilities are utilized.
The construction industry will continue to be given only limited surveillance
 to ensure that no changes in practice  occur.
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 011  and  Gas  Extraction

       The  oil  and gas extraction industry clearly has considerable potential
 as a problem area.   Field observations and conversations with farmers  and
 ranchers indicate that good practices for handling oil field wastes are not
 in force.   Infiltration pits and ponds are still  commonly used for disposal of
 oil  field  wastes  and brines.  The Gillette landfill  is also used for disposal
 of oily  wastes and  brines where these fluids are allowed to freely percolate
 into the subsurface.  A reportedly common practice for disposal of oil  field
 wastes is  to truck the material to an isolated stretch of road and open the
 discharge  valve whi-le moving.

       The  Wyoming Oil  and Gas Commission has been contacted to identify their
 involvement  in monitoring.   It was found, however, that this agency is  in-
 volved in  leasing matters and compilation of exploration and production sta-
 tistics  and  that  little monitoring is done.

      The oil and  gas extraction industry is  probably  a major potential  ground-
 water pollution source,  however,  it will  not be  investigated in a  regional
 sense in this  study.    On mine leases where  oil and gas wells  exist or  have
 existed, potential  groundwater impacts  win  be evaluated.   Based  on informa-
 tion collected so far,  these wells are of minor concern because they are so
 few  in number,  and  are  under close scrutiny  because of their proximity  to the
 mining operations.

 Coal  Strip Mining

      Coal  strip mining  and its related sources have considerable potential to
 produce  groundwater  quality degradation.  Certain sources  have considerably
 more potential  for  harm than others.   As should  be evident  from the discussion
 in the previous sections, only limited monitoring  has  been carried  out on the
 sources  identified  in  Section 2.   Where monitoring of sources  has  been  con-
 ducted it  has  not been  source oriented but directed toward  assessing back-
 ground quality levels,  with the hope that eventually  any changes in quality
 due  to pollutants will  show up in the monitoring  program.

      The above approach is  the traditional approach utilized,  but  it is con-
 trary to the objectives  of Public Laws 92-500 and 93-523, which are aimed at
 preventing, reducing, and eliminating groundwater quality degradation.   Once
 pollutants show up  in a  background quality monitoring system,  in many cases,
 it is  too  late to institute controls.   Source monitoring is the key to
determining which controls  to implement and  whether they are working.

      Seven coal  strip mining operations  in  various stages  of  development were
inventoried in Section 2  for potential  groundwater pollution sources.   Dif-
ferences in the kinds of  sources  present  exist as well  as in the methods of
disposal  used.  Sufficient  information does  not exist to develop a  priority
ranking for each  individual  mine  site  nor for all  the sites collectively.  No
monitoring  is underway on many of the  sources.  As a  result, the preliminary
ranking which follows will  relate only to two major coal  strip mining related
sources:   pit discharges, and spoils.


                                     223

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     For active mining, the pit discharge represents a potential source of
groundwater  pollution.   Much of the pit discharge is derived from native
groundwater,  and this may not appear to be an important source.  However, a
number of potential pollutants can enter the pit discharge.  Explosives, sew-
age effluents, spoils, coal, and other sources can contribute pollutants to
pit discharge.  Pit discharge as a source is transitory in nature; that is,
holding ponds would generally be moved from place to place as mining proceeds.
Pit discharge to surface water will generally be done throughout mining and will
move from place to place, but will be concentrated along the alluvial channels.

     The relocation of spoils produces a changing chemical environment that
will be a permanent potential source.  Some  groundwater  will likely always
be  in contact with the lower parts of the emplaced spoils.  Also, some stream-
flow will generally be rerouted, after mining, over the spoils along the for-
mer floodplains and percolation will occur in some areas.  Holdi-ng ponds placed
on  the spoils would be transitory  in nature.   Groundwater contacting the spoils
will tend to occur indefinitely in specific parts of the reclaimed areas.  In
any area where  groundwater was present in or above the coal seam prior to min-
ing, the spoils will  generally be  in contact with  groundwater  after mining
ceases.  Spoils  placed below the water table have top priority among mining
sources for  the  following reasons:

     •  The  soil and  vadose zone are bypassed, thus there  is no pollutant
        attenuation in these zones

     •  Generally, materials with  the highest pollution potential are placed
        at the bottom of the spoils, and it is this area that will be contacted
        by groundwater

     •  This source is permanent in a sense and can contribute pollutants over
        decades and centuries.

     Another priority for mining sources would be for rerouted surface water
percolating  into the  spoils.  The  extent of this problem depends largely on
the chemical nature and hydraulic  head ultimately established in the spoils
and underlying materials and the permeability of spoils beneath the stream
channel.  This source will also be permanent and can contribute pollutants for
many decades or centuries after mining ceases.  A third priority for mining
sources would be percolation of streamflow below points of pit discharge.  The
extent of this problem is presently poorly known due to a  lack of adequate
monitoring of pit discharge.  Dilution due to mixing with  surface water from
natural runoff would  limit the potential groundwater pollution.

     The quality of surface water  can also be adversely impacted because  in
some parts of the leases the  groundwater  contributes to surface water flow.
Over the long term, substantial increases in the salinity  of surface water
could occur.   This in turn could exert profound adverse impacts on downstream
users of surface water.  This factor alone necessitates continual monitoring
of groundwater  near  the mines.

     Groundwater in   the coal and  overlying formations is  generally  poor  qual-
ity,  and  probably suitable only for industrial use  (with treatment), oil  field

                                     224

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injection, or stock use.  Alternative supplies are often available from deeper
formations; however, the costs of drilling and pumping could be greatly in-
creased.   Similarly, potential water uses in  the future that are presently un-
known could be adversely impacted by lowered  groundwater  quality.  For ex-
ample, toxic substances could make the  local  groundwater  unusable for stock
use.  Secondly, there is generally a downward head gradient in the sedimentary
formations.  Underlying aquifers utilized for drinking water, stock, industrial,
and other  uses could be adversely  impacted.

Coal  Conversion

      Of the  three  coal  conversion  activities  projected  to be implemented in
the project  area,  steam electric power  generation, gasification, and liquifi-
cation, only steam electric power  generation  is  being implemented on a large
scale.  This plant is located on the Wyodak  lease and most of its waste pro-
ducts will be disposed  of  in the mine pits.   The primary waste will be fly ash,
which will be disposed  of  both in  ponds and  as landfill.  Secondary wastes,
e.g., sewage effluent and  sludge,  will  also  be disposed of in ponds or as land-
fill.

Fly Ash Ponds-

      Fly  ash disposal at Wyodak in  the  future is presently not well known.
Past  disposal has  been  in  slurry form to a pond  in the  North Pit.  Future dis-
posal will apparently be of two types:   (1)  fly  ash  solid landfill ing in the
pit,  and  (2) fly ash slurry pond.   The  fly ash slurry pond will be the deposi-
tory  for  a number  of types of wastes, many of which  are liquid.

      Top  priority  should be given  to fly ash  disposal  in the pit at levels
which will lie below groundwater level.  This top priority is based on:

      •   The disposal is basically permanent, and pollutants can be produced
          for decades or centuries

      •   Certain trace  elements may well qualify fly ash as a hazardous waste

      •   The soil  and vadose zone  are bypassed and thus pollutant attenuation
          in  these  zones will not occur

      •   Large volumes  of  fly ash  will  be disposed  of.

      Second"priority should be given to the  fly  ash  slurry pond.  This priority
is based  on:

       •  The waste water disposed  to this pond  presents a ready source of
          water for leaching pollutants  to the groundwater

       •  This source contains a variety of  pollutants,  including  salinity  from
          brine disposal and metals from the  fly  ash.
                                     225

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     Third priority should be given to fly ash land-filled above the water table
and beneath rerouted streams.  This priority is based on:

      •   A ready source of water is available for leaching

      •   The fly ash may well qualify as a hazardous waste.


MUNICIPAL

     The principal potential municipal sources of groundwater pollution are
the landfill, sewage treatment plant,  and water treatment plant.   Individual
wells within the City's well field are subject to damage from any of these
three sources and in the long term from the mining operations.  Currently not
enough is known about the regional hydrogeology of the area or the long-term
impacts of the mines on water to estimate what damages to the City's well
field might result.

      Only limited monitoring has been done on the landfill, sewage treatment
plant, or water treatment plant.  As a result, the following priority ranking
had to be based on knowledge of what has happened under similar circumstances
for the same source type at other locations.  Only when more detailed informa-
tion  is available will it be possible to develop a ranking which has a high
degree of validity.

Landfill
     The City of Gillette landfill is the recipient of pollution-yielding
 sources rang.ing from domestic solid waste to a wide gamut of hazardous wastes.
 Because no records are kept of incoming wastes, the volume and concentrations
 of  specific pollutants are unknown.  Regulations found in the Resource Conser-
 vation and Recovery Act of 1976 will, hopefully, change this in the near future.
 The oily waste areas represent point sources of organic wastes as well as macro-
 constituents and trace contaminants.  Leakage of these pollutants into the
 underlying coal seam may be occurring if the sealing action of sludges and
 sediments is not effective.  In fact, seepage may have been considered as the
 prime method for maintaining pit capacity.  The dead animal pit and  the septic
 tank disposal area also may introduce microorganisms into shallow groundwater.
 The garbage trenches receive direct surface runoff during storm periods, pro-
 moting leachate generation and subsequent movement into the exposed,  fractured
 coal seam.   Some attenuation of pollutants may occur within the landfill proper,
 particularly microorganisms.  Nevertheless, excessive levels of macroconsti-
 tuents and microconstituents and organics enter with the initial leachate.  The
 problem of  groundwater contamination from pollutants at the landfill may  be
 accentuated by the final hydraulic heads imposed by the elevation of the site
 and by movement through scoria and fractures.

 Sewage Treatment Plant

     The municipal  sewage treatment plant sources consist of leaking tanks,
sludge disposal  pond, an oxidation pond, and flow of effluent  into  Donkey
Creek.   Leakage of raw effluent and entrained organic loads and microorganisms

                                     226

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 into  the  shallow groundwater  system may be particularly insidious.   Effluent
 flow  into Donkey Creek will  recharge over a fairly large area.   Dilution of
 effluents may mitigate pollution to a considerable extent.   Windmill  wells
 which are still  at  the demonstration stage of development may be using this
 blended  source at this time.  Wastewater beyond the treatment facility will
 eventually be diverted to Wyodak and will then be removed largely from the list
 of pollutant sources (except for pipe leakage).

 Water Treatment Plant

      The prime source associated with the water treatment plant is brine from
 the desalination plant, particularly if this brine is discharged into a well.
 That  is,  pollutants are introduced directly into water-bearing  strata, by-
 passing  the entire vadose zone.  Because of poor operation, however,  the
 electrodialysis plant is generally inoperative.  Seepage of brine into Stone
 Pile  Creek may also introduce pollutants into a shallow water-table  aquifer.
 Wastewater in the lime softening plant is not a particularly severe  source
 because  the quality is not too different from natural groundwater.

 Septic Tanks

      A final possible source is septic tank leach fields in the outlying
 trailer  courts.   This source may be particularly harmful to nearby privately-
 owned water supply wells.

      There is little question that the above ranking for the major sources
presented in Table 10-1 are very preliminary.  This should not be surpris-
ing in view of the limited monitoring which has been done on the sources
identified in Section 2.  These sources probably represent only  part  of the
problem,  but do provide a starting point around which a complete monitoring
program can be designed.

      Data and information gaps are almost total for many of the sources iden-
 tified throughout the project area.  The one area of knowledge  showing some
 degree of completeness is the geologic framework at the seven mine sites.
 This  is  not the case for the three major potential pollution sources for the
 Gillette area.

      The next phase of the study will involve designing a monitoring program
 which includes the limited monitoring which has taken place thus far.  The
 information obtained from this program will be used to verify and update the
 priority ranking, to identify and  implement controls, and  to monitor the
 effectiveness of these controls.
                                      227

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              TABLE 10-1.   PROJECT AREA  POTENTIAL POLLUTION SOURCE  PRIORITY RANKING BY  MAJOR CATEGORY
ro
ro
oo
       Coal strip mining
        Coal  conversion
           Municipal
       1.  Spoils  (below water table)

       2.  Spoils  (above water table
             below ponds or streams)

       3.  Pit discharge (to streams)
1.   Fly ash (below water  table)

2.   Fly ash slurry pond

3.   Fly ash solids (above water
      table)
1.   Hazardous  wastes  at  landfill

2.   Disposal well  water  treatment
      plant

3.   Oily waste ponds  at  landfill

4.   Garbage  trench at landfill

5.   Sewage effluent to Donkey Creek

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REFERENCES
   229

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                                  REFERENCES


AMAX Coal Co., Mining Plan Update for Belle Ayr South Mine, Campbell County,
     Wyoming, 1977.

AMAX Coal Co., Mining Plan Update for Eagle Butte Mine, Campbell  County,
     Wyoming, 1977a.

Anderson and Kelly Co., Potential Ground-Water Development at Gillette.
     Wyoming, prepared for the City of Gillette, Wyoming, 1977.

ARCO, Mining Plan Update for Black Thunder Coal Mine. Campbell County,
     Wyoming, 1977.

Attari, A., Fate of Trace Constituents of Coal During Gasification. PB 223 001,
     EPA 650/2-73-004, Final  Report, Chicago Illinois, Institute of Gas Tech-
     nology, 1973.

Back, W., and B.B. Hanshaw, "Chemical Geohydrology," Advances in Hydroscience,
     (V.T. Chow, ed.), Academic Press, Vol 2, 1965.

Biggar, J.W., and D.R. Nielsen, "Miscible Displacement and Leaching Phenomenon
     in  Irrigation of Agricultural Lands," (R.M. Hagen, H.R. Haise, and T.W.
     Edminster, eds.), Agronomy, No. 11, American Society of Agronomy, 1967.

Black Hills Power and Light Co., Application for a Certificate of Public Con-
     venience and Necessity,  re proposed steam-electric generating plant at
     Wyodak mine, Wyoming, 1973.

Bower,  C.A., L.V. Wilcox, G.W.  Akin, and M.G. Keyes, "An Index of the Tendency
     of CaC03 to Precipitate  from Irrigation Waters," Soil Science, Society of
     American Proc., No.  29,  pp 91-92, 1965.

Breckenridge, R.M., Gary B. Glass, Forrest K. Root, and William G. Wendell,
     Campbell County. Wyoming Geologic Map Atlas and Summary of Land. Water.
     and Mineral Resources, County Resource Series No. 3, The Geological
     Survey of Wyoming, Laramie, Wyoming, December 1974.

Buol, S.W., F.D. Hole, and R.J. McCracken, Soil Genesis and Classification.
     Iowa State University Press, Chapter 9, p 116, 1973.

Carter  Oil  Co., Rawhide Mining Plan Update. Campbell County, Wyoming.
     30 CFR 211, Vol 1, 1977.
                                     230

-------
Cordero Mining  Co., Mining  Plan  Update.  Wyoming  Department of Environmental
     Quality, Cheyenne,  Wyoming,  1976.

Council for Agricultural  Science  and  Technology, Application of Sewage Sludge
     to Cropland,  U.S. Environmental  Protection  Agency, Office of Water	
     Programs Operations, EPA-430/9-76-013,  1976.

Dames and Moore,  Inc., Preliminary  Reclamation Feasibility Study  Proposed
     Belle Fourche Coal  Mine  near Gillette.  Wyoming. proparpH for s.m nn
     Co., Denver,  Colorado, 1974.

Davidson, J.M., Li-Tse Ou,  and P.S.C. Rao, "Behavior of High Pesticide Concen-
     trations in  Soil Water," Residual Management by Land Disposal. Proceedings
     of Hazardous  Waste  Symposium.  (W.H.  Fuller, ed.l. U.S. Environmental
     Protection Agency,  EPA-600/9-76-015, 1976.

Davis, R.W., "Hydrologic  Factors  Related to  Coal Development in the Eastern
     Powder River Basin," Wyoming Geological Association Guidebook. 28th Annual
     Field Conference, Geology and  Energy Resources of the Powder River, Casper,
     Wyoming, 1976.

Dean, R.B., and J.E. Smith, "The  Properties  of Sludges," Proceedings of  the Joint
     Conference on Recycling  Municipal Sludges and Effluents on Land, Champaign,
     Illinois,  1973.

Deming, S.A., Natural Sealing Potential  of Raw Sewage Stabilization Lagoons.
     Unpublished  M.S. Thesis, Department of  Civil Engineering, The University of
     Arizona, 1963.

Donaldson, W.T.,  "Trace  Organics  in Water,"  Environmental Science and Technology,
     Vol 11, No.  4, pp 348-351,  1977.

Drever, J.I., J.W. Murphy,  and R.C. Surdam,  "The Distribution of As, Be, Cd, Ca,
     Hg, Mo, Pb,  and U Associated with the Wyodak Coal Seam, Powder River Basin,
     Wyoming,"  Contributions  to Geology,  The University of Wyoming, Vol  15, No.
     2, pp 93-101, 1977.

Fuller, Wallace H., and Allan D.  Halderman,  Management for the Control of Salts
     in Irrigated  Soils.  College  of Agriculture, Bulletin A-43, University of
     Arizona, 1975.

Fuller, W.H., Movement of Selected  Metals, Asbestos, and Cyanide in Soil:  Appli-
     cations to Waste Disposal Problems,  U.S. Environmental Protection Agency,
     EPA-600/2-77-020, 1977.

Gilbert, R.G.,  C.P. Gerba,  R.C. Rice, H.  Bouwer, C. Wallis, and J.L.  Melnick,
     "Virus and Bacteria Removal  from Wastewater by Land Treatment,  Applied and
     Environmental Microbiology,,  Vol  32,  No. 3,  pp 333-338, 1976.

Glass,  Gary B., "Update on the Powder River  Coal Basin," in Wyoming Geological
     Association 28th Annual Field  Conference Guide Book, pp 209-220,  1976.
                                    231

-------
 Grove, G.W.,  "Use of Gravity Belt Filtration for Sludge Disposal," Hydrocarbon
      Processing, pp 82-84, 1975.

 Health Education Service, Manual of Instruction for Sewage Treatment  Plant
      Operators, Albany, New York, no date.

 Hem,  J.D., Study and Interpretation of the Chemical., Characteristics of Natural
      Water, U.S. Geological Survey Water-Supply Paper 1473, 1970.

 Hodson,  W.G., Chemical Analysis of Ground-Water in the Powder River Basin and
      Adjacent Areas, Northeastern Wyoming, Wyoming Department of Economic
      Planning and Development, 1971.

 Jones,  D.C.,  W.S. Clark, J.C. Lacy, W.F. Holland, and E.D. Sethness,  Moni-
      toring Environmental  Impacts of the Coal and Oil Shale Industries:
      Research and Development Needs, Radian Corporation, Austin, Texas, pre-
      pared for the  U.S. Environmental Protection Agency, Environmental Moni-
      toring and Support Laboratory, Las Vegas, Nevada, EPA-600/7-77-015,
      February 1977.

 Keefer,  W.R., and R.F. Hadley, Land and Natural Resource Information  and Some
      Potential  Environmental Effects of Surface Mining of Coal in the
      Gillette Area, Wyoming, U.S. Geological Survey, Circular 743, 27 pp,
      1976.

 Keeney,  D.R.,  and R.E. Wildung, "Chemical Properties of Soils," Soils for.
      Management of  Organic Wastes and Waste Water, Soil Science, American
      Society  of Agronomy, Crop Science Society of America, Madison, Wisconsin,
      1977.

 Kerr-McGee Coal Corp., Mining Plan Update, Jacobs Ranch Mine, Campbell County,
      Wyoming,  1977.

 King, N.I., Maps Showing Occurrence of Ground Water in the Gillette Area,
      Campbell  County, Wyoming, U.S. Geological Survey Miscellaneous Investi-
      gations Series Map I-848-E, 1974.

 Kohnke, Helmut, Soil Physics. McGraw-Hill Book Co., p 33, 1968.

 Korte, N.E., J. Skopp,  W.H. Fuller, E.E. Niebla, and B.A. Alesii, Trace
     Element Movement in Soils:   Influence of Soil Physical and Chemical
     Properties, Soil  Science, 1977 (in press).

 Lance, J.C., C.P. Gerba, and J.L. Mel nick, "Virus Movement in Soil  Columns  Flood-
     ed with Secondary Sewage Effluent," .Applied and Environmental  Microbiology,
     Vol  32, No. 4,  pp 520-526, 1976.

Law, B.E., "Large-Scale Compaction Structures in the Coal Bearing Fort Union
     and Wasatch Formations, NE Powder River Basin, Wyoming," in Wyoming
     Geological Association, 28th Annual Field Conference Guidebook,  pp  221-
     229, 1976.~
                                      232

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Lawrence Liver-more Laboratory, LLL  In Situ Coal Gasification Program, Quarterly
     Progress Report. October thru  December  1976, 1977.	

Leenheer, J.A., and E.W.D. Huffman, Jr., "Classification of Organic Solutes in
     Water by Using Macroreticular  Resins,"  Journal of Research of the U S
     Geological Survey. Vol 4, No.  6, pp 737-751, 1976.  "	"

Lowham, H.W., Techniques for Estimating Flow Characteristics of Wyoming
     Streams, U.S. Geological Survey, Water  Resources Division, Water Re-
     sources Investigation 76-112,  Cheyenne, Wyoming, 1976.

Lowry, M.E., and G.C. Lines, Chemical Analyses of Ground Water in the Bighorn
     Basin. Northwestern Wyoming, U.S. Department of the Interior, Geological
     Survey, Water Resources Division, prepared in cooperation with the
     Wyoming State Engineer, 1972.

Lund, L.J., A.L. Page, and C.O. Nelson, "Movement of Heavy Metals Below Sewage
     Disposal Ponds," Journal of Environmental Quality, Vol 5, No. 3, pp 330-
     334, 1976.       	-^                ™

Mann, J.F., Jr., "Wastewaters in the Vadose  Zone of Arid Regions:  Hydrologic
     Interactions," Ground Water, Vol 14, No. 6, Proceedings of the Third
     National Ground Water Quality  Symposium, pp 367-373, 1976.

McElroy, A.D., S.Y. Chin, J.W. Nebgen, A. Aleti, and F.W. Bennett, Loading Func-
     tions for Assessment of Water  Pollution from Nonpoint Sources, U.S. Environ-
     mental Protection Agency, EPA-600/2-76-151, 1976.

McTernan, W.F., The Bacteriological and Chemical Examination of Waters Associated
     with a Surface Coal Mine in Northeastern Wyoming, M.S. Thesis, University of
     Wyoming, 1974.

Metcalf and Eddy,  Inc., Wastewater  Engineering. McGraw-Hill Book Co., 1972.

Missouri Basin Engineering Health Council, Waste Treatment Lagoons-State of the
     Art. U.S. Environmental Protection Agency, 17090 EHX 97/71, 1971.

Mitchell, R.L., "Trace  Elements in  the Soil," Chemistry of the Soil, 2nd Ed.,
     F.E. Bear (ed.), Reinhold, New York, 1964.

Murray, C.R., and  E.B.  Reeves, Estimated Use of Water in the United States in
     1970, Circular 676, U.S. Geological Survey, Washington, D.C., 37 pp, 1972.

Nelson, Haley, Patterson and Quirk, Inc., Water Facilities Inventory-Remedial
     Work Program  for the City of Gillette.  Wyoming, Greeley,  Colorado, 1976.

Pavoni, J.L., J.E. Heer, Jr., and D.J. Hagerty, Handbook of Solid Waste Disposal,
     Material and  Energy Recovery,  Van Nostrand Reinhold Co.,  1975.

Pohland, F.G., and R.S. Engelbrecht, Impact  of Sanitary  Landfills-An Overview of
     Environmental Factors and Control Alternatives, American  Paper  Institute,
     1976.

                                      233

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 Power,  J.F.,  J.J.  Band,  P.M.  Sandoval, and W.O. Willis,  "Nitrification  of
      Paleocene  Shale," Science, Vol  183,  No. 4129,  p  1077,  15  March  1974.

 Rahn,  P.,  Potential of Coal  Strip Mine Spoils as  Aquifers  in the  Powder River
      Basin, Old West  Regional Council, Project No.  10470025, 1976.

 Rechard,  P.A.,  and V.R.  Hasfurther,  "Hydrology,"  Final  Environmental  Assessment-
      Black Thunder Mine  Site, Vol II, Sec. VII, Black Thunder  Research  Team,
      University of Wyoming,  1976.

 Rhoades,  J.D.,  "Drainage for Salinity Control," Drainage for Agriculture,
      Agronomy Monograph  No.  17, American  Society  of Agronomy,  1974.

 Robertson, J.M.,  C.R. Touissaint, and M.A. Jerque,  Organic  Compounds  Entering
      Ground Water from a Landfill, U.S. Environmental Protection  Agency,  EPA-
      660/2-74-077, 1974.

 Runnels,  D.D.,  "Wastewaters  in the Vadose Zone of Arid  Regions:   Geochemical
      Interactions," Ground Water, Vol 14, No. 6,  Proceedings of the Third
      National  Ground  Water Quality Symposium, pp  374-385, 1976.

 Sartor, J.D.,  and G.B. Boyd, Water Pollutants in  Urban  Runoff, U.S. Environmental
      Protection Agency,  National Conference on 208  Planning and Implementation,
      Washington,  D.C., 1977.

 Schaub, S.A.,  E.P.  Meier, J. Kolmer, and C. Sorbu,  Land, Application of  Waste-
      water:   The  Fate of Viruses, Bacteria and Heavy  Metals at a  Rapid  Infiltra-
      tion  Site, National  Technical Information Service,  AD-A011 263,  1975.

 Scurlock,  A.C., A.W. Lindsey, T.  Fields,  Jr., and D.R. Duber,  Incineration in
     Hazardous  Waste Management,  USEPA,  SW-141, Hazardous Waste Division, Office
     of Solid Waste Management Programs,  1975.

 Silberman, P.T., On-Site Disposal  Systems and Septage Treatment and Disposal,
     U.S.   Environmental  Protection Agency, National Conference on 208 Planning
     and Implementation,  Washington,  D.C., 1977.

 Sirf%nt  v.E.,  Characteristics of Wyoming Stock-Water Ponds and  Dike Spreader
     Systems.  WRRI Series No. 47,  University of Wyoming, Laramie, Wyoming, 1974.

 Soil Conservation Service (SCS),  Soil Survey Reconnaissance. Campbell County.
     Wyoming,  Series 39,  No. 22,  T931T~~

 Soil Conservation Service (SCS),  National Engineering Handbook. Section 4,
     Hydrology, Chapter 7, p 7.2,  1971.

Sommers, I.E., D.W. Nelson, and K.J.  Yost, "Variable  Nature of Chemical Compo-
     sition of Sewage Sludges-" Journal  of Environmental Quality, Vol 5,  No.  3,
     pp 303-306, 1976.                ~~	
                                     234

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Stone  R   and D.F  Snoeberger  Evaluation of the Native Hvdrrf.nic Characteris
     tics QT tne helix Coal and Associated strat^  Hoe Creek Sitp — f^mnhpi i
     County, Wyoming, U^^FTh^^^
       rvHfn pffeCtS °f tt)e D1Sp°Sal Of Industrial Waste within a Sani-
     tary Landfill Environment," Residual Management by Land Disposal. Proceed-
     ings of Hazardous Waste S.ymposmm. (U.H. F.mprT PH ) ,  n <:  FnU^nmanta1
     Protection Agen.cy, EPA-600/9-76-015, 1976.

Tait, D.B., Geohydrology, Coal Creek Property. Campbell County, Wyoming. ARCO,
     Resource Development Group, 1976.

Todd, O.K., R.M. Tinlin, K.D. Schmidt, and L.G.  Everett, Monitoring Groundwater
     Quality:  Monitoring Methodology, U.S. Environmental Protection Agency,
     EPA-600/4-76-026, 1976.

TOUPS, Inc., Evaluation of Community Water Supplies  in Energy Impact Areas. U.S.
     Environmental Protection Agency, 1977.

University of Wyoming, Atlantic Richfield Co., Black Thunder Mine, Final Environ-
     mental Assessment, Vols II and III, October 1976.

U.S. Bureau of Land Management, Final Environmental  Assessment, Eastern Powder
     River Coal Basin, FES-74-75, 1974.

U.S. Department of Interior, Final Environmental Impact Statement, Eastern
     Powder River Coal Basin of Wyoming, Proposed Mining and Reclamation by
     Carter Oil Co., VOL IV, 1974.

U.S. Department of Interior, Final Environmental Statement, Proposed Plan of
     Mining and Reclamation, Belle Ayr South Mine. AMAX Coal Co., FES 75, 1975.

U.S. Environmental Protection Agency, Process Design Manual for Sludge Treatment
     and Disposal. EPA Technology Transfer, EPA-625/1 -74-006, 1974.

U.S. Environmental Protection Agency, A Primer on Wastewater Treatment, Office
     of Public Affairs (A-107), 1976a.

U.S. Environmental Protection Agency, Decision Makers Guide in Solid Waste
     Management, Office of Solid Waste Management Programs, SW-500, 1976b.

U.S. Environmental Protection Agency, "Residual  Management by Land Disposal,"
     Proceedings of the Hazardous Waste Research Symposium, Tucson, Arizona,
     February 1976, Municipal Environmental Research Laboratory, Cincinnati,
     Ohio, EPA-600/9-76-015, 270 pp, 1976c.
                                    235

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U S  Environmental Protection Agency, Surface Coal Mining  in  the  Northern  Great
     Plains of the Western United States, Office of  Energy Activities,  OEA 76-1,
     1976d.

U.S. Geological Survey, Coal Resources of the United States,  Geological  Survey
     Bulletin 1412, January 1974a.
  V

U.S. Geological Survey, Final Environmental Statement.  Carter Oil  Co.,  North
     Rawhide Mine, Proposed Mining and Reclamation Plan. Vol  4, October 1974b.

U.S. Geological Survey, Powder River Basin  Regional  EIS, Vol  1, October 1974c.

U.S. Geological Survey, Final Environmental Statement.  Proposed Plan of Mining
     and  Reclamation,  Belle Ayr South Mine. AMAX Coal Coal Company,  Coal Lease
     W-0317682. Campbell  County, Wyoming, FES 75-86,  1975.

U.S. Geological Survey, Draft Environmental Statement,  Proposed Mining  and
     Reclamation  Plan. Eagle Butte Mine, AMAX Coal Company, Coal  Lease  W-0313773,
     Campbell County.  Wyoming. DES 76-36, 1976.

U.S. Geological Survey,   Final Environmental Statement, Proposed  Plan of Mining
     and  Reclamation,  Cordero Mine, Sun Oil Cojnpany.  Coal  Lease W-8385,  Campbell
     County, Wyoming,  FES 76-22, 1976a.

Weinstein, N.J.,  Waste Oil Recycling and Disposal. U.S. Environmental Protection
     Agency, EPA-670/2-74-052, 1974.

Wiram, V.P., Evaluation of Overburden within the Belle  Ayr Mine Property of AMAX
     Coal Co., Gillette, Wyoming, nd.

Wyatt,  J.M., and P.E.  White, Jr., Sludge Processing, Transportation  and  Dis-
     posal/Resource Recovery:  A Planning Perspective Water Quality  Management
     Guidance.  U.S. Environmental  Protection Agency, WPD 12-75-01, 1975.

Wyodak  Resource Development Corp.,  Mining Plan Update.  1977.

Wyoming Water Planning Program (The), The Wyoming Water Framework  Plan.  1973.
                                     236

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APPENDIX A
     237

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                                 APPENDIX A
                          METRIC CONVERSION TABLE*
 Non-metric  units

 inch (in)

 feet (ft)       2
 square feet (ft )
 yards
 square yards
 mi 1 es
 square miles
 acres

 gallons

 cubic feet  (ft3)
 barrels (oil)
 acre/ft
 gallons/square  foot per minute
 cubic feet/second
 gallons/minute**
 gallons/day
 million gallons/day

 pounds

 tons  (short)

 pounds/acre
 parts per million (ppm)
Multiply by
                Metric units
25.4
2.54
0.3048
0.290 >
91.44
0.914
        10
 .6093
 .599
 .047 >
3.
3.
3.
1,
 .785 x
 .785 x
 .785
 .590 x
1.108 x
40.74
3.532 x
6.308 x
3.785
28.32
0.028
0.454
4.536 x
9.072 x
0.907
1.122
1
          -2
10
4.047 x 10
        10
        10

        107
        10'

        10'
        10
  -1
  3
  -3
  -2
        10
          -4
                     (m2)
millimeters (mm)
centimeters (cm)
meters (m)
square meters
centimeters (cm)
square meters (m2)
kilometers (km)
square kilometers
square meters
hectares (ha)
cubic centimeters
cubic meters
liters
liters
liters
liters/square meter per minute
liters/second
liters/second
liters/day
liters/second
cubic meters/second
kilograms
tons  (metric)
kilograms
tons  (metric)
kilograms/hectare
milligrams per  liter  (mg/1)
**
 * English units were used in this report because of their current  usage and
   familiarity in industry and the hydrology-related sciences.
   1 gpm = 1.6276 afa.
                                     238

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            Abbreviations for Units of Measure
afa         acre-feet annually
Btu         British thermal  units
cc          cubic centimeters
epm         equivalents per million
g           grams
h           hour
meq         mi Hi equivalents
mmhos/cm    micromhos per centimeter
ppm         parts per million
s           seconds
                             239

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                                  TECHNICAL REPORT DATA
                           (Please read Instructions on the reverse before completing)
1. REPORT NO.
  EPA-600/7-79-024
                                                           3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
  GROUNDWATER QUALITY MONITORING OF WESTERN  COAL  STRIP
  MINING:   Identification and Priority  Ranking  of
  Potential  Pollution Sources                   	
             5. REPORT DATE
              January  1979
             6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
  Lome G.  Everett (editor)
             8. PERFORMING ORGANIZATION REPORT NO.

              GE77TMP-50
9. PERFORMING ORGANIZATION NAME AND ADDRESS
  General Electric Company-TEMPO
  Center for Advanced Studies
  Santa Barbara, California 93102
                                                           10. PROGRAM ELEMENT NO.
              1NE625
             11. CONTRACT/GRAN1
              68-03-2449
                             NO.
 12. SPONSORING AGENCY NAME AND ADDRESS
                                                           13. TYPE OF REPORT AND PERIOD COVERED
  U.S. Environmental Protection Agency-Las  Vegas,  NV
  Office of Research and Development
  Environmental Monitoring and Support  Laboratory
  Las Vegas, NV  89114                	
             14. SPONSORING AGENCY CODE

              EPA/600/07
 15. SUPPLEMENTARY NOTES
                      EMSL-LV Project  Officer for this report is Leslie G. McMillion.
  Commercial telephone (702) 736-2969,  x241,  or FTS 595-2969, x241.
 i6.ABSTRACT  y^g rep0r^ -js the first  in  a  series  of several to come out of  a  5-year
  study to assess the impact on groundwater  quality of coal strip mining  in the  Western
  United States.  Presented is a preliminary priority ranking of potential  sources of
  groundwater pollution in an area within  Campbell  County, Wyoming, overlying one of
  the major coal fields in the Powder River  Basin.
       The priority ranking was developed  by making a thorough review of  the  existing
  data available from monitoring activities  of mining companies and various county,
  State, and Federal agencies.  Potential  pollution sources and methods of  waste dis-
  posal at seven operating mines and  also  in the  vicinity of the City of  Gillette were
  inventoried.   The data were carefully  reviewed  to identify the potential  pollutants
  associated with each source.  Groundwater  usage was inventoried.  An appraisal of the
  hydrogeologic framework and existing groundwater quality was developed.   By super-
  imposing the  identified potential groundwater pollution sources on the  hydrogeologic
  framework and making estimates of pollutant mobilities from these sources,  the pre-
  liminary priority ranking was developed.   The study has revealed a major  data  and
  information gap in the understanding of  pollutant mobilities and, thus, the priority
  ranking presented will likely undergo  considerable revision as the program  progresses.
  This report was submitted in partial fulfillment of Contract #68-03-2449  by General
  Electric-TEMPO, Center  for  Advanced Studies, under the sponsorship of  the U.S.
  Environmental  Protection Aaencv.	
 7.
                               KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
  Groundwater
  Groundwater quality
  Water  pollution sources
  Coal mines
  Mine wastes
  Waste  disposal
  Strip  mining
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
 Groundwater movement
 Monitoring methodology
 Pollutant identification
 Pollutant source ranking
  08D
  08H
  081
  15B
 8. DISTRIBUTION STATEMENT

  RELEASE TO  PUBLIC
19. SECURITY CLASS (This Report)
  UNCLASSIFIED
21. NO OF PAGES
  264
                                              20. SECURITY CLASS (This page)
                                                UNCLASSIFIED
                           22.
EPA Form 2220-1 (Rev. 4-77)   PREVIOUS EDITION is OBSOLETE

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